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Sample records for silver np sol

  1. Preparation of counterion stabilized concentrated silver sols.

    Science.gov (United States)

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

    2011-07-01

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

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  3. Antibacterial ethylene propylene rubber impregnated with silver nanopowder: AgNP@EPR

    Directory of Open Access Journals (Sweden)

    Marzieh Miranzadeh

    2016-01-01

    Full Text Available Following our interest in reaching for a molded rubber article with possible detergent contact applications, durable silver nanopowder (AgNP is synthesized by arc discharge, then mixed with varying ratios of ethylene propylene rubber (EPR, affording novel AgNP@EPR nanocomposites. X-ray diffraction (XRD patterns of AgNP as well as AgNP@EPR show no trace of impurity, while scanning electron microscopy (SEM indicates an average diameter of 50 nm for the former. Transmission electron microscopy (TEM images while confirm the SEM results, show quite a few 5 nm AgNP particles lying beside some micro crumbs. Our DC arc discharge technique involves explosion of movable silver anode and static cathode by a current pulse between 5 to 10 A cm-2. A solution blending method is employed for preparation of AgNP@EPR nanocomposites. The AgNP is first dispersed in toluene using an ultrasonic homogenizer, and then thoroughly mixed with EPR in the same solvent whose removal gives nanocomposites of 2, 4, 6 and 8 vol% AgNP in EPR,  showing strong antibacterial activity against both Escherichia coli and Staphylococcus aureus.

  4. Control size of silver nanoparticles in sol-gel glasses

    Science.gov (United States)

    Renteria, Victor M.; Celis, Antonio C.; Garcia-Macedo, Jorge A.

    2000-10-01

    By the sol-gel processing, silver ions in presence of stabilizing function (3-thiocyanatopropyl)triethoxysilane are reduced by heating gels at 180 C for several times in air atmosphere. The spectroscopic Uv-Vis observations, confirm silver nanoparticles presence with peak maximum around 350 nm. The optical properties of the metallic particles are observed at room temperature as function of time, and the absorption spectra practically do not change, which indicated they are trapped and stabilized within the fine porous silica cage. Mie theory calculations, considering the mean free path effect of the conduction electrons, are compatible with experimental spectra, indicating homogeneity in size and form of the metallic nanoparticles. Smithard correlation curve, between half width height (W1/2) of the optical absorption and the particle diameter 2r, predict silver particles size between 4 and 10 nm, during composite heating. Activation energy was measured and compared with previous data on similar systems and the probable reduction process are discussed.

  5. Effects of silver nanoparticle (Ag NP on oxidative stress biomarkers in rat

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    Akram Ranjbar

    2014-04-01

    Full Text Available Objective(s: Nanotechnology and nanoparticles are increasingly recognized for their potential applications in aerospace engineering, nanoelectronics, and environmental remediation, medicine and consumer products. More importantly is the potential for the application of silver nanoparticles (Ag NPs in the treatment of diseases that require maintenance of circulating drug concentration or targeting of specific cells or organs the aim of this study was to investigate the possible protective role of Ag NP antioxidative biomarkers in rats. Ag NPs are used to investigate the potential risks for the environment and health. Materials and Methods: Rats received Ag NP, 5, 50, 250 and 500 mg/kg/day IP. After two week of treatment, the activity of enzymatic scavengers such as glutathione peroxidase (GPx, superoxide dismutase (SOD and total antioxidant capacity (TAC of blood samples were measured. Results: Ag NP in 5, 50, 250 and 500 mg/kg reduced activities of CAT, SOD and increased TAC in plasma. Conclusion: In this study, Ag NP with 500mg/kg induced activities of CAT, SOD and decreased TAC. It is concluded that antioxidative properties of Ag NP is dose dependent.

  6. Polylactic acid (PLA)/Silver-NP/VitaminE bionanocomposite electrospun nanofibers with antibacterial and antioxidant activity

    Science.gov (United States)

    Munteanu, Bogdanel Silvestru; Aytac, Zeynep; Pricope, Gina M.; Uyar, Tamer; Vasile, Cornelia

    2014-10-01

    The antibacterial property of silver nanoparticles (Ag-NPs) and the antioxidant activity of Vitamin E have been combined by incorporation of these two active components within polylactic acid (PLA) nanofibers via electrospinning (PLA/Ag-NP/VitaminE nanofibers). The morphological and structural characterizations of PLA/Ag-NP/VitaminE nanofibers were performed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy and X-ray diffraction. The average fiber diameter was 140 ± 60 nm, and the size of the Ag-NP was 2.7 ± 1.5 nm. PLA/Ag-NP/VitaminE nanofibers inhibited growth of Escherichia coli, Listeria monocytogenes and Salmonella typhymurium up to 100 %. The amount of released Ag ions from the nanofibers immersed in aqueous solution was determined by Inductively Coupled Plasma Mass Spectrometry, and it has been observed that the release of Ag ions was kept approximately constant after 10 days of immersion. The antioxidant activity of PLA/Ag-NP/VitaminE nanofibers was evaluated according to DPPH (2,2-diphenyl-1-picrylhydrazyl) method and determined as 94 %. The results of the tests on fresh apple and apple juice indicated that the PLA/Ag/VitaminE nanofiber membrane actively reduced the polyphenol oxidase activity. The multifunctional electrospun PLA nanofibers incorporating Ag-NP and Vitamin E may be quite applicable in food packaging due to the extremely large surface area of nanofibers along with antibacterial and antioxidant activities. These materials could find application in food industry as a potential preservative packaging for fruits and juices.

  7. Influence of negative charge on the optical properties of a silver sol

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    JOVAN M. NEDELJKOVIC

    2000-03-01

    Full Text Available The effects of negative charge on the optical properties of a silver sol prepared using sodium borohydride as a reductant were studied. The oscillations in the position of the maximum and the intensity of the surface plasmon absorption band were obesrved. The observed effects were explained as a consequence of the fluctuation of the density of free electrons due to the alternate charging and discharging of the silver particles. The charging process involves electron injection from borohydride ions and intermediate species formed during the course of the metal-catalyzed hydrolysis of borohydride ions (BH3OH-, BH2(OH2 and BH(OH3- into the silver particles, while discharge of the silver sol, by reduction of water to hydrogen, limits the attainable negative charge on the particles.

  8. A concetration-dependent model for silver colloids in nanostructured sol-gel materials

    Science.gov (United States)

    Garcia-Macedo, Jorge A.; Franco, Alfredo; Renteria, Victor; Valverde-Aguilar, Guadalupe

    2005-08-01

    We report on the physical modelling of the photoconductive response of nanostructured sol-gel films in function of the silver nitrate concentration (ions and colloids). This model considers several factors as the silver nitrate concentration and the transport parameters obtained. The model is compared with others commonly used. 2d-hexagonal nanostructured sol-gel thin films were prepared by dip-coating method using a non-ionic diblock copolymer Brij58 (surfactant) to produce channels into the film. Silver colloids (metallic Ag0 nanoparticles ) were obtained by spontaneous reduction process of Ag+ ions to Ag0. These nanoparticles were deposited into the channels formed by the surfactant. The structure was identified by X-ray diffraction and TEM. An absorption band located at 430 nm was detected by optical absorption; it corresponds to the plasmon surface. Fit to this band with modified Gans theory is presented. Photoconductivity studies were performed on films with silver ions and films with silver colloids to characterized their mechanisms of charge transport in the darkness and under illumination at 420, 633 nm wavelengths. Transport parameters were calculated. The films with silver colloids exhibit a photovoltaic effect stronger than the films with silver ions. While, the last ones possesses a photoconductivity behaviour.

  9. A Widely Applicable Silver Sol for TLC Detection with Rich and Stable SERS Features

    Science.gov (United States)

    Zhu, Qingxia; Li, Hao; Lu, Feng; Chai, Yifeng; Yuan, Yongfang

    2016-04-01

    Thin-layer chromatography (TLC) coupled with surface-enhanced Raman spectroscopy (SERS) has gained tremendous popularity in the study of various complex systems. However, the detection of hydrophobic analytes is difficult, and the specificity still needs to be improved. In this study, a SERS-active non-aqueous silver sol which could activate the analytes to produce rich and stable spectral features was rapidly synthesized. Then, the optimized silver nanoparticles (AgNPs)-DMF sol was employed for TLC-SERS detection of hydrophobic (and also hydrophilic) analytes. SERS performance of this sol was superior to that of traditional Lee-Meisel AgNPs due to its high specificity, acceptable stability, and wide applicability. The non-aqueous AgNPs would be suitable for the TLC-SERS method, which shows great promise for applications in food safety assurance, environmental monitoring, medical diagnoses, and many other fields.

  10. Optical spectroscopy of arsenic- and silver-containing sol-gel coatings

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M.A.; Paje, S.E.; Llopis, J. [Departamento de Fisica de Materiales, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Madrid (Spain); Villegas, M.A.; Fernandez Navarro, J.M. [Departamento de Vidrios, Instituto de Ceramica y Vidrio, Madrid (Spain)

    1999-05-07

    Sol-gel silica coatings doped with 1 mol% silver and/or 1 mol% arsenic oxide have been investigated by photoluminescence (PL) and optical absorption (OA) spectroscopy. The presence of Ag{sup +} ions in the silica host has been monitored by recording a luminescence peak located between 320 and 330 nm upon excitation with 228 nm light, whereas the formation of small particles of metallic silver has been assessed by recording the absorption band centred at about 405 nm. The luminescence peak has been related to the d{sup 10} 10 {r_reversible} d{sup 9} s parity-forbidden transitions in Ag{sup +}, which are partially allowed by odd-phonon assistance. On the other hand, the absorption peak at about 405 nm arises from the well known surface-plasmon resonance of silver particles. Coating densification under various atmospheres gives rise to significant effects on the PL and OA spectra. Results indicate that, after coating densification in air, most of the silver appears as Ag{sup +} ions, in contrast to coating densification under a 90% N{sub 2}-10% H{sub 2} atmosphere, which favours the formation of small particles of metallic silver. The presence of arsenic oxide in the silver coatings densified in air has been found to improve the stabilization of Ag{sup +} ions, so that partially prevents the formation of colloidal silver under reducing atmospheres. (author)

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

    Science.gov (United States)

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

    2014-01-01

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

  12. 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.

  13. 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.

  14. Silver Nanoparticles (AgNP impregnated filters in drinking water disinfection

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    Rus Alexandru

    2017-01-01

    Full Text Available This paper describes how simple portable devices could eliminate water pathogens by using Silver Nanoparticles, based on their antimicrobial properties. Recent studies indicated that silver nanoparticles can achieve up to 100% antibacterial activity removal. Results are showing that Silver Nanoparticles retention in the filter structure, E. coli bacteria removal, water quality and water flow rate must be evaluated as main efficiency indicators of the designed filters, in order to obtain the optimal filter. To apply the antimicrobial property of Silver in drinking-water treatment, a filter is produced using Additive Manufacturing techniques and coated with different concentrations of silver solutions.

  15. Examination of Sol-Gel Derived Hydroxyapatite Enhanced with Silver Nanoparticles using OCT and Raman Spectroscopy

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    Głowacki Maciej J.

    2017-03-01

    Full Text Available Hydroxyapatite (HAp has been attracting widespread interest in medical applications. In a form of coating, it enables to create a durable bond between an implant and surrounding bone tissues. With addition of silver nanoparticles HAp should also provide antibacterial activity. The aim of this research was to evaluate the composition of hydroxyapatite with silver nanoparticles in a non-destructive and non-contact way. For control measurements of HAp molecular composition and solvent evaporation efficiency the Raman spectroscopy has been chosen. In order to evaluate dispersion and concentration of the silver nanoparticles inside the hydroxyapatite matrix, the optical coherence tomography (OCT has been used. Five samples were developed and examined ‒ a reference sample of pure HAp sol and four samples of HAp colloids with different silver nanoparticle solution volume ratios. The Raman spectra for each solution have been obtained and analyzed. Furthermore, a transverse-sectional visualization of every sample has been created and examined by means of OCT.

  16. Spectrophotometric determination of dissolved oxygen in water and heavy water through the formation of argentocyanide complex from silver sol (Preprint No. CA-5)

    International Nuclear Information System (INIS)

    Pal, Tarasankar; Das, P.K.; Pal, Anjali

    1989-04-01

    A yellow silver sol is used as the colour reagent for the determination of trace amounts of dissolved oxygen in water by following the oxygen and cyanide-dependent decrease in intensity of the coloured silver sol at 415nm. The method is best suited to the routine determination of DO in industrial and natural waters at concentrations down to 50 pph. This is the first report of the determination of DO in water using a yellow silver sol in an alkaline medium. (author). 32 refs., 2 tabs

  17. Modeling of optical absorption of silver prolate nanoparticles embedded in sol-gel glasses

    International Nuclear Information System (INIS)

    Renteria, V.M.; Garcia-Macedo, J.

    2005-01-01

    Silver prolate nanoparticles were obtained in silica gels prepared by the sol-gel process. Heating them at 900 deg. C for few minutes, the samples showed a yellow-orange color. A strong optical absorption with an asymmetric peak centred at 425 nm due to surface plasmon resonance of silver nanoparticles was observed. High-resolution transmission electron microscopy images showed silver prolate particles (average axial ratio AR = 0.76) randomly oriented with broad size distribution. The size changed from 9 to 3 nm and the prolate form changed to almost spherical (AR = 0.92) when the samples were heated longer time at 900 deg. C. In these samples, the absorption peak was shifted from 425 up to 460 nm. After heat treatment, the absorption spectrum did not change any more in some months, indicating that the particles obtained through this method are stable at room temperature. The Gans theory was used to fit the experimental spectra. The fit was not good until we assumed in the calculations all the physical features come from the system such as the volume fraction, shape and size of the metallic particles, and refractive index of the silica matrix. It was necessary to consider also a refractive index that come from oxidation on the surface of the metallic particles. With these considerations the fit with the Gans theory was good enough, and the difference between the calculated and experimental spectra was very small, factor 20 better than when oxidation is ignored. So then, the oxidation from the metallic particles must be taken in account to explain the experimental absorption spectra. These results are discussed

  18. Modeling of optical absorption of silver prolate nanoparticles embedded in sol-gel glasses

    Energy Technology Data Exchange (ETDEWEB)

    Renteria, V.M. [Departamento de Estado Solido, Instituto de Fisica, UNAM, P.O. Box 20-364, 01000 Mexico, Distrito Federal (Mexico); Garcia-Macedo, J. [Departamento de Estado Solido, Instituto de Fisica, UNAM, P.O. Box 20-364, 01000 Mexico, Distrito Federal (Mexico)]. E-mail: gamaj@fisica.unam.mx

    2005-05-15

    Silver prolate nanoparticles were obtained in silica gels prepared by the sol-gel process. Heating them at 900 deg. C for few minutes, the samples showed a yellow-orange color. A strong optical absorption with an asymmetric peak centred at 425 nm due to surface plasmon resonance of silver nanoparticles was observed. High-resolution transmission electron microscopy images showed silver prolate particles (average axial ratio AR = 0.76) randomly oriented with broad size distribution. The size changed from 9 to 3 nm and the prolate form changed to almost spherical (AR = 0.92) when the samples were heated longer time at 900 deg. C. In these samples, the absorption peak was shifted from 425 up to 460 nm. After heat treatment, the absorption spectrum did not change any more in some months, indicating that the particles obtained through this method are stable at room temperature. The Gans theory was used to fit the experimental spectra. The fit was not good until we assumed in the calculations all the physical features come from the system such as the volume fraction, shape and size of the metallic particles, and refractive index of the silica matrix. It was necessary to consider also a refractive index that come from oxidation on the surface of the metallic particles. With these considerations the fit with the Gans theory was good enough, and the difference between the calculated and experimental spectra was very small, factor 20 better than when oxidation is ignored. So then, the oxidation from the metallic particles must be taken in account to explain the experimental absorption spectra. These results are discussed.

  19. SAXS Combined with UV-vis Spectroscopy and QELS: Accurate Characterization of Silver Sols Synthesized in Polymer Matrices.

    Science.gov (United States)

    Bulavin, Leonid; Kutsevol, Nataliya; Chumachenko, Vasyl; Soloviov, Dmytro; Kuklin, Alexander; Marynin, Andrii

    2016-12-01

    The present work demonstrates a validation of small-angle X-ray scattering (SAXS) combining with ultra violet and visible (UV-vis) spectroscopy and quasi-elastic light scattering (QELS) analysis for characterization of silver sols synthesized in polymer matrices. Polymer matrix internal structure and polymer chemical nature actually controlled the sol size characteristics. It was shown that for precise analysis of nanoparticle size distribution these techniques should be used simultaneously. All applied methods were in good agreement for the characterization of size distribution of small particles (less than 60 nm) in the sols. Some deviations of the theoretical curves from the experimental ones were observed. The most probable cause is that nanoparticles were not entirely spherical in form.

  20. PREPARATION OF TITANIA SOL-GEL COATINGS CONTAINING SILVER IN VARIOUS FORMS AND MEASURING OF THEIR BACTERICIDAL EFFECTS AGAINST E. COLI

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    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.

  1. Preparation and SERS performance of Au NP/paper strips based on inkjet printing and seed mediated growth: The effect of silver ions

    Science.gov (United States)

    Weng, Guojun; Yang, Yue; Zhao, Jing; Zhu, Jian; Li, Jianjun; Zhao, Junwu

    2018-04-01

    Surface-enhanced Raman scattering (SERS) has been widely used in biomedical sensing with the advantages of high sensitivity and label-free. However, the fabrication of SERS substrates with good Raman activity, reproducibility, and low cost is still under development in practical applications. This paper presents a practicable method for fabricating Au NP/paper strips by using inkjet printing and seed mediated growth. Small gold seed synthesized by borohydride reduction was used as ink and printed on the filter paper. The printed gold seed grew in situ in the growth solution and formed the gold nanoparticle (Au NP)/paper strips. The fabricated paper strip was characterized by diffuse reflectance spectroscopy and scanning electron microscopy (SEM). The diffuse reflectance spectra indicated that the Au NP/paper strips had two local surface plasmon resonance (LSPR) peaks: the short one at around 540 nm and the long one located in the range of 640-840 nm. And the long LSPR peak firstly shifted to red then to blue with the increased concentrations of silver ions in growth solution. From the SEM images, the shape of grown Au NPs was diverse, including sphere, rod, ellipsoid, dimer, trimer, and big aggregates. We thought the short peak came from the LSPR of nanospheres and the transvers LSPR of rod and ellipsoid like particles, while the long peak mainly came from the plasmonic coupling of dimer along the inter-particle axis. The obtained Au NP/paper strip with the long peak located around 650 nm had the highest SERS activity, which could be attributed to the plasmon resonance induced local field enhancement and nanogap effect. Also, the SERS performance results indicated the printed SERS strips exhibited satisfied uniformity and stability, demonstrating the potential of Au NP/paper strip in real-world applications.

  2. Examination of Sol-Gel Derived Hydroxyapatite Enhanced with Silver Nanoparticles using OCT and Raman Spectroscopy

    OpenAIRE

    Głowacki Maciej J.; Gnyba Marcin; Strąkowska Paulina; Gardas Mateusz; Kraszewski Maciej; Trojanowski Michał; Strąkowski Marcin R.

    2017-01-01

    Hydroxyapatite (HAp) has been attracting widespread interest in medical applications. In a form of coating, it enables to create a durable bond between an implant and surrounding bone tissues. With addition of silver nanoparticles HAp should also provide antibacterial activity. The aim of this research was to evaluate the composition of hydroxyapatite with silver nanoparticles in a non-destructive and non-contact way. For control measurements of HAp molecular composition and solvent evaporati...

  3. Green Biosynthesis of Silver Nanoparticles using Aqueous Urginea Indica Bulbs Extract and Their Catalytic Activity Towards 4-NP

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    R. Manigandan

    2017-04-01

    Full Text Available A simple, green method is described for the synthesis of silver nanoparticles by reaction of the aqueous solution of Urginea indica (U. I. bulbs extract and AgNO3. In this process, colloidal metallic silver nanoparticles (Ag0 Nps were of a particular interest due to its haunting physicochemical properties. The formation of Ag0 Nps nanoparticles was proved by the significant color change during the preparation. The formation process and color variations by the impact of pH and concentration of extract were analyzed by UV-VIS spectrophotometer. Functional groups present in the extract and Ag0 NPs was characterized by FT-IR spectroscopy. The crystal structure, lattice parameter and crystallite size of synthesized silver NPs was confirmed by X-ray diffraction technique. The X-ray diffraction analysis of the sample showed the formation of nanoparticles with cubic silver structure. Elemental composition and morphology of the metallic silver was widely investigated by FESEM-EDX.

  4. Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique

    Science.gov (United States)

    Mirzaee, Majid; Dolati, Abolghasem

    2014-09-01

    Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3 with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO matrix covered with silver oxide shell, resulting in high quality nanocomposite thin films. The embedment of polyvinylpyrrolidone inhibited the growth of silver nanoparticles and ITO annealed at 350 °C. Delafossite structure of tin-doped AgInO2 was found at higher annealing temperatures. XRD analysis and FESEM micrographs showed that the optimum temperature to prevent the formation of AgInO2 is 350 °C. The embedment of silver particles (5-10 nm) from reduction of silver ion in ITO thin films improved the electrical conductivity and optical transmittance of ITO nanolayers. The lowest stable sheet resistance of 1,952 Ω/Sq for a 321 nm thick and an average optical transmittance of 91.8 % in the visible region with a band gap of 3.43 eV were achieved for silver-doping content of 0.04 M.

  5. Estimation of silver nanoparticles size in SiO2 sol-gel layers by use of UV-VIS spectroscopy

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    Marek Novotný

    2011-12-01

    Full Text Available Silica glass layers containing silver nanoparticles were prepared by the sol-gel method. The layers were deposited on a glass substrate by the dip-coating method, dried and heat treated at various temperatures. The average silver particle size was determined from absorption spectra according to Mie’s theory. A good correlation was found between the calculated values and analysis of HRTEM images. A very narrow size distribution was obtained by this procedure. The average particle size of silver particles fell between 1 and 2 nm for dried samples; in case of glasses treated at 500 and 550°C the size ranged between 2 and 4 nm.

  6. Stability of erbium and silver implanted in silica-titania sol-gel films

    International Nuclear Information System (INIS)

    Ramos, A.R.; Marques, C.; Alves, E.; Marques, A.C.; Almeida, R.M.

    2005-01-01

    We implanted silica-titania sol-gel films with 3 x 10 15 at./cm 2 , 180 keV Er + and 6 x 10 16 at./cm 2 , 140 keV Ag + ions. The energies were chosen so that the profiles of Ag and Er overlap. RBS and ERDA were used to study the behaviour of Ag, Er and H during the heat treatments used to density the films. Implantation causes H depletion at the film surface and an increase in H concentration just beneath the implanted Ag and Er profiles. The total H content decreases by 27% to 75% during implantation. During annealing the H content decreases, with an almost complete H loss after annealing for 35 min at 800 deg. C. The Ag profile remains stable up to 600 deg. C. Above 700 deg. C Ag becomes increasingly mobile. Annealing at 800 deg. C for 35 min results in a nearly constant Ag distribution in the film. The Er profile remains unchanged with heat treatment up to the maximum temperature used (800 deg. C)

  7. The antibacterial and hydrophilic properties of silver-doped TiO{sub 2} thin films using sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xuemin [College of Physics and Electronic Information, Tianjin Normal University, Tianjin, 300387 (China); Hou Xinggang, E-mail: hou226@163.com [College of Physics and Electronic Information, Tianjin Normal University, Tianjin, 300387 (China); Luan Weijiang [College of Biology, Tianjin Normal University, Tianjin, 300387 (China); Li Dejun; Yao Kun [College of Physics and Electronic Information, Tianjin Normal University, Tianjin, 300387 (China)

    2012-08-01

    Ag-TiO{sub 2} composite thin films were deposited on glass slides by sol-gel spin coating technique. The surface structure, chemical components and transmittance spectra were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectrophotometer. The TiO{sub 2} thin films with silver molar ratio from 0 to 10% were tested for its antibacterial property by using Escherichia coliform (E. coli) under irradiation of UV light. The concentration of E. coli was evaluated by plating technique. The influences of different molar ratio of Ag on hydrophilicity and long-term durability of the films were also investigated by measuring the water contact angle. The results showed that the antibacterial ability was significantly improved by increasing silver content comparing with pure TiO{sub 2} thin film, and the best molar ratio of Ag was 5%. While the hydrophilicity of films increased with increasing silver content, and the best molar ratio of Ag was 1%.

  8. Specific behavior of the p-aminothiophenol--silver sol system in their Ultra-Violet-Visible (UV-Visible) and Surface Enhanced Raman (SERS) spectra.

    Science.gov (United States)

    Firkala, Tamás; Tálas, Emília; Mihály, Judith; Imre, Tímea; Kristyán, Sándor

    2013-11-15

    The UV-Visible and Surface Enhanced Raman Spectroscopy (SERS) behavior of silver sol (a typical SERS agent) were studied in the presence of different bifunctional thiols such as p-aminothiophenol, p-mercaptobenzoic acid, p-nitrothiophenol, p-aminothiophenol hydrochloride, and 2-mercaptoethylamine hydrochloride in diluted aqueous solution. Our results confirm that the p-aminothiophenol induced aggregation of citrate stabilized silver colloid originates from its electrostatic nature, as well as the azo-bridge formation cannot be the reason of the observed time dependent UV-Visible spectra. Based on our parallel SERS and electrospray ionization mass spectrometry measurements, we have concluded that certain amount of oxidized form of the probe molecule has to be present for the so-called b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Our findings seem to support the idea that the azo-bridge formation is responsible for the b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Silver nanowires network encapsulated by low temperature sol-gel ZnO for transparent flexible electrodes with ambient stability

    Science.gov (United States)

    Shin, Wonjung; Cho, Wonki; Baik, Seung Jae

    2018-01-01

    As a geometrically engineered realization of transparent electrode, Ag nanowires network is promising for its superior characteristics both on electrical conductivity and optical transmittance. However, for a potential commercialization of Ag nanowires network, further investigations on encapsulation materials are necessary to prevent degradation caused by ambient aging. In addition, the temperature range of the coating process for the encapsulation material needs to be low enough to prevent degradation of polymer substrates during the film coating processes, when considering emerging flexible device application of transparent electrodes. We present experimental results showing that low temperature sol-gel ZnO processed under 130 °C is an effective encapsulation material preventing ambient oxidation of Ag nanowires network without degrading electrical, optical, and mechanical properties.

  10. Structural, optical, electrochemical and photovoltaic studies of spider web like Silver Indium Diselenide Quantum dots synthesized by ligand mediated colloidal sol-gel approach

    Science.gov (United States)

    Adhikari, Tham; Pathak, Dinesh; Wagner, Tomas; Jambor, Roman; Jabeen, Uzma; Aamir, Muhammad; Nunzi, Jean-Michel

    2017-11-01

    Silver indium diselenide quantum dots were successively synthesized by colloidal sol-gel method by chelating with organic ligand oleylamine (OLA). The particle size was studied by transmission electron microscopy (TEM) and the size was found about 10 nm. X-ray diffraction (XRD) was used to study crystalline structure of the nanocrystals. The grain size and morphology were further studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The elemental composition was studied by X-ray photon electron spectroscopy (XPS) and energy dispersive x-ray spectroscopy (EDAX). The capping property of OLA in nanocrystal was also demonstrated by Fourier Transform Infrared spectroscopy (FTIR). The band gap was calculated from both cyclic voltammetry and optical absorption and suggest quantum confinement. The solution processed bilayer thin film solar cells were fabricated with n-type Zinc oxide using doctor blading/spin coating method and their photovoltaic performance was studied. The best device sintered at 450 °C showed an efficiency 0.75% with current density of 4.54 mAcm-2, open-circuit voltage 0.44 V and fill factor 39.4%.

  11. Bioaccumulation of silver in Daphnia magna:Waterborne and dietary exposure to nanoparticles and dissolved silver

    NARCIS (Netherlands)

    Ribeiro, Fabianne; van Gestel, C.A.M.; Pavlaki, M.D.; Azevedo, S.; Soares, A.M.V.M.; Loureiro, S.

    2017-01-01

    Silver nanoparticles (Ag-NP) are incorporated into commercial products as antimicrobial agents, which potentiate their emission to the environment. The toxicity of Ag-NP has been associated with the release of Ag ions (Ag

  12. The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings

    Energy Technology Data Exchange (ETDEWEB)

    Piwonski, Ireneusz, E-mail: irek@uni.lodz.pl [University of Lodz, Department of Technology and Chemistry of Materials, Pomorska 163, 90-236 Lodz (Poland); Kadziola, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna [University of Lodz, Department of Technology and Chemistry of Materials, Pomorska 163, 90-236 Lodz (Poland); Wolszczak, Marian [Technical University of Lodz, Institute of Applied Radiation Chemistry, Wroblewskiego 15, 93-590 Lodz (Poland); Lisowska, Katarzyna; Wronska, Natalia; Felczak, Aleksandra [University of Lodz, Department of Industrial Microbiology and Biotechnology, Pilarskiego 14/16, 90-231 Lodz (Poland)

    2011-06-01

    Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 {+-} 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO{sub 2} nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO{sub 2} covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

  13. The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings

    International Nuclear Information System (INIS)

    Piwonski, Ireneusz; Kadziola, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna; Wolszczak, Marian; Lisowska, Katarzyna; Wronska, Natalia; Felczak, Aleksandra

    2011-01-01

    Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 ± 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO 2 nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO 2 covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

  14. Expedition sol

    DEFF Research Database (Denmark)

    Jacobsen, Aase Roland

    2006-01-01

    Tag på expedition sol rundt i museet. Er der nogen, der har taget en bid af solen? Hvorfor bliver der solformørkelse? Kan vi undvære Solen?......Tag på expedition sol rundt i museet. Er der nogen, der har taget en bid af solen? Hvorfor bliver der solformørkelse? Kan vi undvære Solen?...

  15. NP Science Network Requirements

    Energy Technology Data Exchange (ETDEWEB)

    Dart, Eli [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Rotman, Lauren [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Tierney, Brian [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

    2011-08-26

    The Energy Sciences Network (ESnet) is the primary provider of network connectivity for the U.S. Department of Energy (DOE) Office of Science (SC), the single largest supporter of basic research in the physical sciences in the United States. To support SC programs, ESnet regularly updates and refreshes its understanding of the networking requirements of the instruments, facilities, scientists, and science programs it serves. This focus has helped ESnet to be a highly successful enabler of scientific discovery for over 20 years. In August 2011, ESnet and the Office of Nuclear Physics (NP), of the DOE SC, organized a workshop to characterize the networking requirements of the programs funded by NP. The requirements identified at the workshop are summarized in the Findings section, and are described in more detail in the body of the report.

  16. Study of magnetic structure of neptunium compounds: Np As, Np Sb, Np Se et Np Ru2 Si2

    International Nuclear Information System (INIS)

    Bonnisseau, D.

    1987-11-01

    Magnetic behavior and localization of 5f electrons in actinide compounds is studied experimentally by Moessbauer spectroscopy and neutron diffraction. Binary actinide compounds with a NaCl structure are examined and properties of U, Pu and Np monopnictides and monochalcogenides are recalled. Results of neutron diffraction by NpAs and NpSb are discussed and results of magnetic susceptibility, magnetization, Moessbauer spectroscopy and neutron diffraction measurements on NpSe and NpTe are presented. Magnetic properties of NpRu 2 Si 2 are also presented. Heavy fermion system electronic and magnetic properties are described and theory is discussed. Electronic and magnetic properties of CeCu 2 Si 2 , CeRu 2 Si 2 and URu 2 Si 2 are compared to NpRu 2 Si 2 which has the same crystal structure [fr

  17. Preparation of silver nanocrystals in microemulsion by the γ-radiation method

    International Nuclear Information System (INIS)

    Hongkai Wu; Xiangling Xu; Xuewu Ge; Zhicheng Zhang

    1997-01-01

    Silver colloids of well-defined shape, size were synthesized by γ-ray irradiating silver salt in reversed microemulsions, and then pure silver dry powders were obtained. The sols were studied by absorption spectroscopy, and the silver powders were characterized by Transmission Electron Micrographs (TEM) and X-ray Diffraction (XRD). The effect of radiation dose and aging time was discussed. (Author)

  18. Synthesis and Property of Ag(NP)/catechin/Gelatin Nanofiber

    Science.gov (United States)

    Nasir, Muhamad; Apriani, Dita

    2017-12-01

    Nanomaterial play important role future industry such as for the medical, food, pharmaceutical and cosmetic industry. Ag (NP) and catechin exhibit antibacterial property. Ag(NP) with diameter around 15 nm was synthesis by microwaved method. We have successfully produce Ag(NP)/catechin/gelatin nanofiber composite by electrospinning process. Ag(NP)/catechin/gelatin nanofiber was synthesized by using gelatin from tuna fish, polyethylene oxide (PEO), acetic acid as solvent and silver nanoparticle(NP)/catechin as bioactive component, respectively. Morphology and structure of bioactive catechin-gelatin nanofiber were characterized by scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR), respectively. SEM analysis showed that morphology of nanofiber composite was smooth and had average diameter 398.97 nm. FTIR analysis results were used to confirm structure of catechin-gelatin nanofiber. It was confirmed by FTIR that specific vibration band peak amide A (N-H) at 3286,209 cm-1, amide B (N-H) 3069,396 cm-1, amide I (C=O) at 1643,813 cm-1, amide II (N-H and CN) at 1538,949 cm-1, amide III (C-N) at 1276,789 cm-1, C-O-C from polyethylene oxide at 1146,418 cm-1, respectively. When examined to S. Aureus bacteria, Ag/catechin/gelatin nanofiber show inhabitation performance around 40.44%. Ag(NP)/catechin/gelatin nanofiber has potential application antibacterial medical application.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-01

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

  1. Morphological evolution of the poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester, oxidation of the silver electrode, and their influences on the performance of inverted polymer solar cells with a sol-gel derived zinc oxide electron selective layer

    International Nuclear Information System (INIS)

    Liu, Meng-Yueh; Chang, Chin-Hsiang; Chang, Chih-Hua; Tsai, Kao-Hua; Huang, Jing-Shun; Chou, Chen-Yu; Wang, Ing-Jye; Wang, Po-Sheng; Lee, Chun-Yu; Chao, Cha-Hsin; Yeh, Chin-Liang; Wu, Chih-I; Lin, Ching-Fuh

    2010-01-01

    The inverted polymer solar cell (PSC) based on a sol-gel derived zinc oxide (ZnO) thin film as an electron selective layer is investigated. The device performance is improved after the fabricated device is placed in air for a few days. The improvement is attributed to the self-organization of the poly(3-hexylthiophene)/[6,6]-phenyl-C 61 -butyric acid methyl ester layer and oxidation of the silver electrode with time, resulting in a significant enhancement in the short circuit current, fill factor and open circuit voltage. The investigation shows that the inverted PSC based on ZnO thin film exhibits a high efficiency of 3.8% on the 6th day after fabrication without the use of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) and encapsulation.

  2. This Is So NP!

    Directory of Open Access Journals (Sweden)

    Elizaveta Bylinina

    2010-12-01

    Full Text Available The construction we are discussing is a recent American English construction (though it can be found in a number of other languages as well with an individual-denoting noun phrase (NP in the predicate position modified by a degree modifier that typically occurs with gradable adjectives, as in 'This is so Obama!' We attempt to look deeper into the structure and compositional semantics of this construction, and though we do not provide a complete analysis of it, we believe that the study of this construction can contribute to questions of gradable predicate semantics, multidimensionality, degree constructions and proper name semantics.ReferencesDik, S. 1968. Coordination: Its Implications for the Theory of General Linguistics. NorthHolland, Amsterdam.Doetjes, J. 1997. Quantifiers and Selection. Ph.D. thesis, Leiden University.Gary-Prieur, M.-N. 1991. ‘La modalisation du nom propre’. Langue Francaise 92: 49–62.Gary-Prieur, M.-N. 1994. Grammaire du nom propre. Paris: Le Seuil.Gary-Prieur, M.-N. 2001. L’individu pluriel: Les noms propres et le nombre. Paris: CNRS Editions.Geurts, B. 1997. ‘Good news about the description theory of names’. Journal of Semantics 14: 319–348.http://dx.doi.org/10.1093/jos/14.4.319Heim, I. 2000. ‘Degree Operators and Scope’. Proceedings of SALT 10: 40–64.Heim, I. & Kratzer, A. 1998. Semantics in generative grammar. Oxford: Blackwell.J. Hay, C. Kennedy & Levin, B. 1999. ‘Scale structure underlies telicity in ‘degree achievements”. Semantics and Linguistic Theory 9: 127–44.Kagan, O. & Alexejenko, S. 2010. ‘The Adjectival Suffix -ovat as a Degree Modifier in Russian’. To appear in proceedings of Sinn und Bedeutung 15.Kamp, H. & Partee, B. 1995. ‘Prototype theory and compositionality’. Cognition 57:129–191.http://dx.doi.org/10.1016/0010-0277(9400659-9Kennedy, C. 1999. Projecting the adjective: The syntax and semantics of gradability and comparison. New York: Garland. (1997 UCSC Ph.D thesis

  3. Nano-silver induces dose-response effects on the nematode Caenorhabditis elegans

    DEFF Research Database (Denmark)

    Ellegaard-Jensen, Lea; Alstrup Jensen, Keld; Johansen, Anders

    2012-01-01

    Toxicity of nano-formulated silver to eukaryotes was assessed by exposing nematodes (Caenorhabditis elegans) to two types of silver nanoparticles (AgNPs): with average primary particle diameters of 1 nm (AgNP1) and 28 nm (AgNP28, PVP coated), respectively. Tests were performed with and without pr...

  4. Biosynthesis of silver nanoparticles by plants crude extracts and ...

    African Journals Online (AJOL)

    Aghomotsegin

    and bioactive silver-containing Na2O CaO 2SiO2 glass prepared by sol-gel method. J. Mater. Sci. Mater. Med. 15(7):831-837. Chanda S (2014). Silver nanoparticles (medicinal plants mediated): a new generation of antimicrobials to combat microbial pathogens – a review. In: Mendez-Vilas, A. (Ed.), Microbial Pathogens ...

  5. Release of silver nanoparticles from outdoor facades

    International Nuclear Information System (INIS)

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

    2010-01-01

    In this study we investigate the release of metallic silver nanoparticles (Ag-NP) from paints used for outdoor applications. A facade panel mounted on a model house was exposed to ambient weather conditions over a period of one year. The runoff volume of individual rain events was determined and the silver and titanium concentrations of 36 out of 65 runoff events were measured. Selected samples were prepared for electron microscopic analysis. A strong leaching of the Ag-NP was observed during the initial runoff events with a maximum concentration of 145 μ Ag/l. After a period of one year, more than 30% of the Ag-NP were released to the environment. Particles were mostly 2 S. - We provide direct evidence for the release of silver nanoparticles from exterior paints to the aquatic environment.

  6. Controlled generation of silver nanocolloid in amorphous silica materials

    International Nuclear Information System (INIS)

    Gil, C.; Garcia-Heras, M.; Carmona, N.; Villages, M. A.

    2004-01-01

    Amorphous silica-based materials bulk and superficially doped with silver nano colloids were prepared. Bulk doped glasses were obtained by conventional melting and doped monolithic slabs by sol-gel. Superficially doped glasses were obtained by ion-exchange and doped coatings by sol-gel. The samples were characterised by TEM and UV-VIS spectrometry. Depending on the composition, the silver incorporation process, and the thermal treatments, several colourings were obtained. By controlling these parameters, metallic silver nano colloids can be generated in the matrices studied. Colloids aggregation and growing up depends on the matrix nature and on the experimental process carried out. (Author) 10 refs

  7. Removal of silver nanoparticles by coagulation processes

    International Nuclear Information System (INIS)

    Sun, Qian; Li, Yan; Tang, Ting; Yuan, Zhihua; Yu, Chang-Ping

    2013-01-01

    Highlights: • This study investigated the removal of AgNP suspensions by four regular coagulants. • The optimal removal efficiencies for the four coagulants were achieved at pH 7.5. • The removal efficiency of AgNPs was affected by the natural water characteristics. • TEM and XRD showed that AgNPs or silver-containing NPs were adsorbed onto the flocs. -- Abstract: Commercial use of silver nanoparticles (AgNPs) will lead to a potential route for human exposure via potable water. Coagulation followed by sedimentation, as a conventional technique in the drinking water treatment facilities, may become an important barrier to prevent human from AgNP exposures. This study investigated the removal of AgNP suspensions by four regular coagulants. In the aluminum sulfate and ferric chloride coagulation systems, the water parameters slightly affected the AgNP removal. However, in the poly aluminum chloride and polyferric sulfate coagulation systems, the optimal removal efficiencies were achieved at pH 7.5, while higher or lower of pH could reduce the AgNP removal. Besides, the increasing natural organic matter (NOM) would reduce the AgNP removal, while Ca 2+ and suspended solids concentrations would also affect the AgNP removal. In addition, results from the transmission electron microscopy and X-ray diffraction showed AgNPs or silver-containing nanoparticles were adsorbed onto the flocs. Finally, natural water samples were used to validate AgNP removal by coagulation. This study suggests that in the case of release of AgNPs into the source water, the traditional water treatment process, coagulation/sedimentation, can remove AgNPs and minimize the silver ion concentration under the well-optimized conditions

  8. Toxicity, Bioaccumulation and Biotransformation of Silver Nanoparticles in Marine Organisms

    Science.gov (United States)

    The toxicity, bioaccumulation and biotransformation of citrate and polyvinylpyrrolidone (PVP) capped silver nanoparticles (NPs) (AgNP-citrate and AgNP-PVP) and titanium dioxide (TiO2) NPs in marine organisms via marine sediment exposure were investigated. Results from 7-d sedimen...

  9. Silver nanoparticle toxicity to retinal pigment epithelial cells in vitro is influenced by particle size and coating, but not UVA radiation

    Science.gov (United States)

    Silver nanoparticles (AgNP) are being introduced into textiles, medical devices, cleaning/disinfecting products and other goods because of their antibiotic properties. Some nanomaterials, including silver, have been developed into drug delivery systems that can be administered di...

  10. Synthesis and characterization of silver nanoparticles in AOT microemulsion system

    International Nuclear Information System (INIS)

    Zhang Wanzhong; Qiao Xueliang; Chen Jianguo

    2006-01-01

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

  11. Accumulation of silver nanoparticles by cultured primary brain astrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Luther, Eva M; Koehler, Yvonne; Dringen, Ralf [Center for Biomolecular Interactions Bremen, University of Bremen, PO Box 330440, D-28334 Bremen (Germany); Diendorf, Joerg; Epple, Matthias, E-mail: ralf.dringen@uni-bremen.de [Inorganic Chemistry and Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Universitaetsstrasse 5-7, D-45117 Essen (Germany)

    2011-09-16

    Silver nanoparticles (AgNP) are components of various food industry products and are frequently used for medical equipment and materials. Although such particles enter the vertebrate brain, little is known on their biocompatibility for brain cells. To study the consequences of an AgNP exposure of brain cells we have treated astrocyte-rich primary cultures with polyvinylpyrrolidone (PVP)-coated AgNP. The incubation of cultured astrocytes with micromolar concentrations of AgNP for up to 24 h resulted in a time- and concentration-dependent accumulation of silver, but did not compromise the cell viability nor lower the cellular glutathione content. In contrast, the incubation of astrocytes for 4 h with identical amounts of silver as AgNO{sub 3} already severely compromised the cell viability and completely deprived the cells of glutathione. The accumulation of AgNP by astrocytes was proportional to the concentration of AgNP applied and significantly lowered by about 30% in the presence of the endocytosis inhibitors chloroquine or amiloride. Incubation at 4 {sup 0}C reduced the accumulation of AgNP by 80% compared to the values obtained for cells that had been exposed to AgNP at 37 {sup 0}C. These data demonstrate that viable cultured brain astrocytes efficiently accumulate PVP-coated AgNP in a temperature-dependent process that most likely involves endocytotic pathways.

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

    Science.gov (United States)

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

    2015-04-28

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

  13. Gastrointestinal absorption of Np in rats

    International Nuclear Information System (INIS)

    Wirth, R.; Volf, V.

    1985-01-01

    The effect of Np mass and the acidity of the administered Np solutions as well as the age, sex and nutritional status of the animals injected or gavaged with 239Np or 237Np were determined. The latter factor proved to be dominant for absorption of Np from the gut. Thus in fasting weanling and young adult male rats, the absorption of 239Np was sixfold higher (0.18% and 0.12%, respectively) than in fed ones (0.03% and 0.02%, respectively). Absorption by fasted adult females was 0.05% of the administered 239Np, about half of that of adult males. Raising the Np-mass gavaged to fasted female rats to 1 and 10 mg 237Np/kg resulted in an absorption of 0.23% and 0.26%, respectively. Thus, an increased absorption of Np in adult rats seems to be expected only if a large mass is ingested. No dependence of the absorption of Np on nitric acid concentration was found. The data obtained after oral administration of 238Pu and 239Np to adult rats suggest that the f1 factor recommended by the ICRP for fractional absorption of soluble Np compounds from the gut should be decreased, whereas the f1 factor for soluble Pu compounds should be raised

  14. Reversible sol-gel-sol medium for enzymatic optical biosensors

    NARCIS (Netherlands)

    Safaryan, S.; Yakovlev, A.; Pidko, E.A.; Vinogradov, A.; Vinogradov, V.

    2017-01-01

    In this paper we for the first time report a reversible sol-gel-sol approach to obtain optical enzymatic biosensors with improved enzyme stability and good sensitivity by using desktop inkjet printing. The developed technique is based on the bio-inorganic inks allowing for a sol-gel-sol transition

  15. Transport of silver nanoparticles in single fractured sandstone

    Science.gov (United States)

    Neukum, Christoph

    2018-02-01

    Silver nanoparticles (Ag-NP) are used in various consumer products and are one of the most prevalent metallic nanoparticle in commodities and are released into the environment. Transport behavior of Ag-NP in groundwater is one important aspect for the assessment of environmental impact and protection of drinking water resources in particular. Ag-NP transport processes in saturated single-fractured sandstones using triaxial flow cell experiments with different kind of sandstones is investigated. Ag-NP concentration and size are analyzed using flow field-flow fractionation and coupled SEM-EDX analysis. Results indicate that Ag-NP are more mobile and show generally lower attachment on rock surface compared to experiments in undisturbed sandstone matrix and partially fractured sandstones. Ag-NP transport is controlled by the characteristics of matrix porosity, time depending blocking of attachment sites and solute chemistry. Where Ag-NP attachment occur, it is heterogeneously distributed on the fracture surface.

  16. Silver nanoparticles embedded in zeolite membranes: release of silver ions and mechanism of antibacterial action

    Science.gov (United States)

    Nagy, Amber; Harrison, Alistair; Sabbani, Supriya; Munson, Robert S; Dutta, Prabir K; Waldman, W James

    2011-01-01

    Background The focus of this study is on the antibacterial properties of silver nanoparticles embedded within a zeolite membrane (AgNP-ZM). Methods and Results These membranes were effective in killing Escherichia coli and were bacteriostatic against methicillin-resistant Staphylococcus aureus. E. coli suspended in Luria Bertani (LB) broth and isolated from physical contact with the membrane were also killed. Elemental analysis indicated slow release of Ag+ from the AgNP-ZM into the LB broth. The E. coli killing efficiency of AgNP-ZM was found to decrease with repeated use, and this was correlated with decreased release of silver ions with each use of the support. Gene expression microarrays revealed upregulation of several antioxidant genes as well as genes coding for metal transport, metal reduction, and ATPase pumps in response to silver ions released from AgNP-ZM. Gene expression of iron transporters was reduced, and increased expression of ferrochelatase was observed. In addition, upregulation of multiple antibiotic resistance genes was demonstrated. The expression levels of multicopper oxidase, glutaredoxin, and thioredoxin decreased with each support use, reflecting the lower amounts of Ag+ released from the membrane. The antibacterial mechanism of AgNP-ZM is proposed to be related to the exhaustion of antioxidant capacity. Conclusion These results indicate that AgNP-ZM provide a novel matrix for gradual release of Ag+. PMID:21931480

  17. Enhanced visible light absorption and reduced charge recombination in AgNP plasmonic photoelectrochemical cell

    Directory of Open Access Journals (Sweden)

    Samaila Buda

    Full Text Available In this research work, silver nanoparticles (AgNP were synthesized using a simple solvothermal technique, the obtained AgNP were used to prepare a titania/silver (TiO2/Ag nanocomposites with varied amount of Ag contents and used to fabricated a photoanode of dye-sensitized solar cell (DSSC. X-ray photoelectron spectroscopy (XPS was used to ascertain the presence of silver in the nanocomposite. A photoluminance (PL spectra of the nanocomposite powder shows a low PL activity which indicates a reduced election- hole recombination within the material. UV–vis spectra reveal that the Ag in the DSSC photoanode enhances the light absorption of the solar cell device within the visible range between λ = 382 nm and 558 nm nm owing to its surface plasmon resonance effect. Power conversion efficiency was enhanced from 4.40% for the pure TiO2 photoanode based device to 6.56% for the device fabricated with TiO2/Ag due to the improvement of light harvesting caused by the localized surface plasmonic resonance effect of AgNP. The improvement of power conversion was also achieved due to the reduced charge recombination within the photoanode. Keywords: Nanoparticle, Silver, Plasmonic, Power, Photon

  18. Effect of media composition on bioavailability and toxicity of silver and silver nanoparticles in fish intestinal cells (RTgutGC).

    Science.gov (United States)

    Minghetti, Matteo; Schirmer, Kristin

    2016-12-01

    To understand conditions affecting bioavailability and toxicity of citrate-coated silver nanoparticles (cit-AgNP) and dissolved silver at the luminal enterocyte interface, we exposed rainbow trout (Oncorhynchus mykiss) gut cells (RTgutGC) in media of contrasting composition: two amino acid-containing media, one of which was supplemented with proteins, as can be expected during digestion; and two protein and amino acid-free media contrasting low and high chloride content, as can be expected in the lumen of fish adapting to freshwater or seawater, respectively. Dose-response curves were generated measuring cell metabolic activity, membrane and lysosome integrity over a period of 72 hours. Then, nontoxic doses were applied and total silver accumulation, metallothionein and glutathione reductase mRNA levels were determined. The presence of proteins stabilized cit-AgNP keeping them in suspension. Conversely, in protein-free media, cit-AgNP agglomerated and settled, resulting in higher cellular accumulation of silver and toxicity. Chloride concentrations in exposure media modulated the toxicity of AgNO 3 but not of cit-AgNP. Moreover, while amino acid-containing media are protective against AgNO 3 , likely due to the formation of thiolate complexes, they are only partially protective against cit-AgNP. Viability assays indicated that lysosomes are targets of cit-AgNP, supporting the hypothesis that cit-AgNP exert toxicity intracellularly. Metallothionein, a sensor of metal bioavailability, was induced by cit-AgNP in high chloride medium but not in low chloride medium, indicating that chloride might have a role in mobilizing silver from intercellular vesicles. Overall, this study shows that AgNP bioavailability and toxicity in the intestine is linked to its luminal content.

  19. Two new Np--Ga phases: α-NpGa2 and metastable m-NpGa2

    International Nuclear Information System (INIS)

    Giessen, B.C.; Elliott, R.O.

    1976-01-01

    Following an earlier study of metastable Np-rich Np--Ga alloys, rapidly quenched Np--Ga alloys with 63 to 80 at. pct. Ga were prepared and studied. Two new NpGa 2 phases, both with an AlB 2 type structure, were found: α-NpGa 2 , with a = 4.246A, c = 4.060A, c/a = 0.956, and m-NpGa 2 , with a = 4.412A, c = 3.642A, c/a = 0.825. While m-NpGa 2 was observed only in very fast quenched (splat cooled) samples and appears to be metastable, α-NpGa 2 is probably an equilibrium phase. In a splat cooled alloy with 75 at. pct. Ga, another, unidentified, metastable phase was observed. Crystal chemical discussions of atomic volumes, interatomic distances and axial ratios are given; the volume difference between the two forms of NpGa 2 is correlated with a valence change of Np

  20. Influences of the coating on silver nanoparticle toxicity in a chronic test with Daphnia magna

    DEFF Research Database (Denmark)

    Sakka, Y.; Mackevica, Aiga; Skjolding, Lars Michael

    2015-01-01

    coated AgNP in a chronic Daphnia test. One type of AgNP was coated with citrate (cAgNP), the other AgNP were generally uncoated (pAgNP; p= pure), but sterically stabilized by an organic dispersant. Particles with a similar shape and diameter were chosen. The focus of the study was to relate observed......Sources for differences in silver nanoparticle toxicity at standardized conditions can be numerous. They range from particle properties and their actual concentrations to differences in uptake or depuration by the test organisms. In the present study we compared the toxicity of two differently...... differences in toxicity to characteristics of the AgNP, like size or surface potential, or to their corresponding behaviour during the test, like dissolution or uptake. The characteristics and the behaviour of the AgNP were investigated for changes in stability and especially the release of silver ions...

  1. Effect of silver nanoparticles on human mesenchymal stem cell differentiation

    Directory of Open Access Journals (Sweden)

    Christina Sengstock

    2014-11-01

    Full Text Available Background: Silver nanoparticles (Ag-NP are one of the fastest growing products in nano-medicine due to their enhanced antibacterial activity at the nanoscale level. In biomedicine, hundreds of products have been coated with Ag-NP. For example, various medical devices include silver, such as surgical instruments, bone implants and wound dressings. After the degradation of these materials, or depending on the coating technique, silver in nanoparticle or ion form can be released and may come into close contact with tissues and cells. Despite incorporation of Ag-NP as an antibacterial agent in different products, the toxicological and biological effects of silver in the human body after long-term and low-concentration exposure are not well understood. In the current study, we investigated the effects of both ionic and nanoparticulate silver on the differentiation of human mesenchymal stem cells (hMSCs into adipogenic, osteogenic and chondrogenic lineages and on the secretion of the respective differentiation markers adiponectin, osteocalcin and aggrecan.Results: As shown through laser scanning microscopy, Ag-NP with a size of 80 nm (hydrodynamic diameter were taken up into hMSCs as nanoparticulate material. After 24 h of incubation, these Ag-NP were mainly found in the endo-lysosomal cell compartment as agglomerated material. Cytotoxicity was observed for differentiated or undifferentiated hMSCs treated with high silver concentrations (≥20 µg·mL−1 Ag-NP; ≥1.5 µg·mL−1 Ag+ ions but not with low-concentration treatments (≤10 µg·mL−1 Ag-NP; ≤1.0 µg·mL−1 Ag+ ions. Subtoxic concentrations of Ag-NP and Ag+ ions impaired the adipogenic and osteogenic differentiation of hMSCs in a concentration-dependent manner, whereas chondrogenic differentiation was unaffected after 21 d of incubation. In contrast to aggrecan, the inhibitory effect of adipogenic and osteogenic differentiation was confirmed by a decrease in the secretion of

  2. Study of Np speciation in citrate medium

    Energy Technology Data Exchange (ETDEWEB)

    Bonin, L.; Den Auwer, C.; Ansoborlo, E.; Moisy, P. [CEA Valrho - DEN/DRCP/SCPS, Bagnols sur Ceze (France); Cote, G. [ENSP - LECA, UMR 7575, Paris (France)

    2007-07-01

    In the framework of the French Environmental Nuclear Toxicology program, additional experiments related to the decorporation of actinides are planned. Decorporation is the removal or release from target organs (bones, liver, kidney..), tissues or cells of radioactive material previously incorporated in them, using chelating agents or other administrated pharmaceutical agents. The contradictory data on the neptunium complexation behaviour within blood and its transfer to target organs, as well as the inefficiency of therapeutic treatments, led us to study the complexation of this element with biological constituents. Within this purpose, the in vitro behaviour of Np(IV) and Np(V) in simple media simulating biological fluids was studied. This study was more specifically focused on the behaviour of neptunium with citrate ion, which is an essential component in a number of metalloenzyme active sites. In order to determine the speciation of this system, spectrophotometry was more particularly used. Concerning the complexation phenomenon, the existence of several complexes of Np(V) with various acido-basic forms of the citrate anion was observed; regarding Np(IV), complexes with Cit{sup 3-} have been observed. From the quantitative study of these equilibria, the values of the absolute constants for the complexation of Np(IV) and Np(V) with citrate were determined. Concerning the stability of neptunium towards oxydo-reduction, it was confirmed that Np(VI) was very quickly reduced to Np(V) by the citrate anions, whereas Np(IV) was stable. In the case of Np(V), it was observed that, depending on the pH and the citrate concentration, Np(V) was unstable and was reduced to Np(IV). The E-pH diagrams, constructed using the stability constants determined in this study, showed that this instability was due to the Np(V) disproportionation. (orig.)

  3. Np(VI)/Np(V) in concentrated carbonate medium; Np(VI)Np(V) en milieu carbonate concentre

    Energy Technology Data Exchange (ETDEWEB)

    Offerle, S.; Capdevila, H.; Vitorge, P.

    1995-02-01

    The formal potential, E, of the Np (VI)Np(V) redox couple is measured versus a Ag/AgC1 electrode with junction potential less than 0.002 V, by using cyclic voltammetry in 0.22, 0.55, 1, 1.25 and 1.5 M Na{sub 2}CO{sub 3} solutions, and at T = 5, 15, 25, 35, 45, 55 and 60 deg. C. At each T, E is extrapolated to I 0 (I: ionic strength) by using the Specific Interaction Theory (SIT) formula E(I) E(0) + 9 a{radical}I/1+ Ba{sub i}{radical}I + 2 {delta}{xi}m. At each I, E data are fitted to a second order polynomial expression as a function of T, to deduce the entropy change, {delta}S, and the heat capacity change, {delta}Cp. The variations of {delta}S and {delta}Cp with I calculated by using formulae deduced from the SIT one, are consistent with the data. In the standard conditions E deg.=0.341 {+-} 0.017 V/ESH, {delta}Sdeg. = -190 {+-} 5 J/K/mol, {delta}Cpdeg. -345{+-}750 J/K/mol. {delta}{xi} = 0,15 + 0,05 -(0,005{+-}0,001){delta}T + 0,00004 {delta}T{sup 2} kg /mol, where {delta}T=T-25 deg.C. These numerical values are consistent with the U and Pu ones. The redox potential measured in 1 M Na{sub 2}CO{sub 3} solution, is greater by about 0.06 V than the published ones. Junction potentials might account for this difference. Supplementary materials are added, concerning the calculation of activity of water in a weak electrolyte, and on correlation between the numerical values of {xi}, or with ionic radius. (authors). 12 refs., 20 figs., 19 tabs.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-04-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-02-15

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

  7. Ising formulations of many NP problems

    OpenAIRE

    Lucas, Andrew

    2013-01-01

    We provide Ising formulations for many NP-complete and NP-hard problems, including all of Karp's 21 NP-complete problems. This collects and extends mappings to the Ising model from partitioning, covering and satisfiability. In each case, the required number of spins is at most cubic in the size of the problem. This work may be useful in designing adiabatic quantum optimization algorithms.

  8. Ising formulations of many NP problems

    Directory of Open Access Journals (Sweden)

    Andrew eLucas

    2014-02-01

    Full Text Available We provide Ising formulations for many NP-complete and NP-hard problems, including all of Karp's 21 NP-complete problems. This collects and extends mappings to the Ising model from partitioning, covering and satisfiability. In each case, the required number of spins is at most cubic in the size of the problem. This work may be useful in designing adiabatic quantum optimization algorithms.

  9. Silver niobates

    International Nuclear Information System (INIS)

    Tanirbergenov, B.; Rozhenko, S.P.

    1979-01-01

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

  10. Nuclear Physics studies at ELI-NP

    International Nuclear Information System (INIS)

    Stevenson, P.D.; Goddard, P.M.; Rios, A.

    2015-01-01

    The mission of the Extreme Light Infrastructure – Nuclear Physics (ELI-NP) facility is to use extreme electromagnetic fields for nuclear physics research. At ELI-NP, high-power lasers together with a very brilliant γ-ray beam are the main research tools. Their targeted operational parameters are described. The emerging experimental program of the facility in the field of nuclear physics is reported and the main directions of the research envisioned are presented. The experimental instrumentation, which will operate at ELI-NP for the realization of the research program, is discussed. The expected impact of ELI-NP on the future advance of the field is summarized

  11. An evaluation of the influence of size and radiation in silver nanoparticle toxicity

    Science.gov (United States)

    The antimicrobial properties of silver nanoparticles (AgNP) have made them popular in textile manufacturing, medical technology, and biomedical applications. Studies suggest that after ingestion, nanomaterials are distributed throughout the body to different organs, possibly incl...

  12. Quaternized chitosan/rectorite/AgNP nanocomposite catalyst for reduction of 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Yunzhi [State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Zeng, Xianjie [School of Business Administration, South China University of Technology, Guangzhou 510640 (China); Tan, Weirui [State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Luo, Jiwen, E-mail: holdit@126.com [Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University, Guangzhou 510006 (China); State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640 (China); Liu, Shijie, E-mail: sjliu@163.com [State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640 (China); China Department of Paper and Bioprocess Engineering, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210 (United States)

    2015-10-25

    This study investigated a one-step green fabrication of exfoliated quaternized chitosan/rectorite/AgNP nanocomposites under microwave radiation method. The nanocomposites were characterized by FT-IR, XRD, XPS and TEM. The results revealed that quaternized chitosan and rectorite acted as reducing and stabilizing agents, spherical AgNPs were synthesized greenly and rapidly, meanwhile the layers of rectorite were exfoliated, and when the ratio of quaternized chitosan, rectorite and silver nitrate was 100 mg: 10 mg: 2 mmol, the AgNP content reached the maximum of 2.73%. Then, the quaternized chitosan/rectorite/AgNP nanocomposite was fabricated as a film, which was used in the catalytic reduction from 4-nitrophenol to 4-aminophenol by NaBH{sub 4}. The film showed excellent catalytic efficiency with an activation energy of 29.76 kJ mol{sup −1} and outstanding reusable performance even after catalysis for 10 times. - Graphical abstract: Quaternized chitosan/rectorite/AgNP nanocomposite catalyst was prepared greenly in one pot and fabricated as a film, which showed excellent catalytic efficiency and reusable performance. - Highlights: • Quaternized chitosan and rectorite acted as reducing and stabilizing agents. • Spherical Ag NPs were synthesized greenly and rapidly. • AgNP dispersed well on the surface and the interlayer of exfoliated rectorite. • Quaternized chitosan/rectorite/AgNP nanocomposite was prepared as a film. • The film showed excellent catalytic efficiency and reusable performance.

  13. One-step synthesis and characterization of polyaniline nanofiber/silver nanoparticle composite networks as antibacterial agents.

    Science.gov (United States)

    Poyraz, Selcuk; Cerkez, Idris; Huang, Tung Shi; Liu, Zhen; Kang, Litao; Luo, Jujie; Zhang, Xinyu

    2014-11-26

    Through a facile and effective seeding polymerization reaction via a one-step redox/complexation process, which took place in aqueous medium at ambient temperature, silver nanoparticles (Ag NPs) embedded polyaniline nanofiber (PANI NF) networks were synthesized as antibacterial agents. During the reaction, not only NF morphology formation of the resulting conducting polymers (CPs) but also amplification of the aqueous silver nitrate (AgNO3) solutions' oxidative potentials were managed by vanadium pentoxide (V2O5) sol-gel nanofibers, which acted as well-known nanofibrous seeding agents and the auxiliary oxidative agent at the same time. The PANI/Ag nanocomposites were proven to exhibit excellent antibacterial property against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Antibacterial property performance and average life span of the nanocomposite network were optimized through the homogeneous distribution/embedment of Ag NPs within one-dimensional (1-D) PANI NF matrix. The antibacterial efficacy tests and nanocomposite material characterization results further indicated that the sole components of PANI/Ag have a synergistic effect to each other in terms of antibacterial property. Thus, this well-known catalytic seeding approach via a one-step oxidative polymerization reaction can be considered as a general methodology and a substantial fabrication tool to synthesize Ag NP decorated nanofibrillar PANI networks as advanced antibacterial agents.

  14. The Magnets Puzzle is NP-Complete

    DEFF Research Database (Denmark)

    Kölker, Jonas

    2012-01-01

    In a Magnets puzzle, one must pack magnets in a box subjet to polarity and numeric constraints. We show that solvability of Magnets instances is NP-complete.......In a Magnets puzzle, one must pack magnets in a box subjet to polarity and numeric constraints. We show that solvability of Magnets instances is NP-complete....

  15. Green Synthesis of Silver Nanoparticles and the Study of Optical Properties

    OpenAIRE

    Vasireddy, Ramakrishna; Paul, Rima; Mitra, Apurba Krishna

    2012-01-01

    The synthesis of silver nanoparticles of varying size has been achieved using different molar concentrations of NaOH while the effect of changing the temperature has been studied. AgNO3, gelatine, glucose and NaOH are used as a silver precursor, stabilizer, reducing agent and accelerator respectively. The synthesized nanoparticles have been characterized by a FESEM study, X‐ray diffractometry, Raman spectroscopy and UV‐vis spectroscopy. The colloidal sols of the silver nanoparticles in a biop...

  16. Studies on the antimicrobial properties of colloidal silver nanoparticles stabilized by bovine serum albumin.

    Science.gov (United States)

    Mathew, Thomas V; Kuriakose, Sunny

    2013-01-01

    Colloidal silver nanoparticles were synthesised using sol-gel method and these nanoparticles were stabilised by encapsulated into the scaffolds of bovine serum albumin. Silver nanoparticles and encapsulated products were characterised by FTIR, NMR, XRD, TG, SEM and TEM analyses. Silver nanoparticle encapsulated bovine serum albumin showed highly potent antibacterial activity towards the bacterial strains such as Staphylococcus aureus, Serratia marcescens, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Asymmetric Flow Field-Flow Fractionation of Manufactured Silver Nanoparticles in Soil Water Extracts

    NARCIS (Netherlands)

    Koopmans, G.F.; Hiemstra, T.; Molleman, B.; Regelink, I.C.; Comans, R.N.J.

    2013-01-01

    Manufactured silver nanoparticles (AgNP) are among the most widely used nanoparticles in consumer products and their unintended release into the environment has become a serious concern. For a meaningful assessment of the risks of AgNP in soils, their concentration and particle-size-distribution in

  18. Identification of NpO{sub 2+x} in the binary Np-O system

    Energy Technology Data Exchange (ETDEWEB)

    Tayal, Akhil, E-mail: aakhiltayal@gmail.com [Synchrotron SOLEIL, L' Orme des Merisiers, Saint-Aubin, BP 48, Gif-sur-Yvette 91192 Cedex (France); Conradson, Steven D., E-mail: St3v3n.c0nrads0n@icloud.com [Josef Stefan Institute, Department of Complex Matter Department, Jamovacesta 39, 1000 Ljubljana (Slovenia); Washington State University, Department of Chemistry, P.O. Box 644630, Pullman, WA 99164 (United States); Baldinozzi, Gianguido, E-mail: gianguido.baldinozzi@centralesupelec.fr [SPMS, LRC Carmen, CNRS and Ecole Centrale Paris, Châtenay-Malabry and CEA/DEN/DANS/DMN/SRMA/LA2M-LRC CARMEN, Gif-sur-Yvette (France); Namdeo, Sonu [Devi Ahilya Vishwavidyalaya, University Campus Khandwa Road, Indore 452001 (India); Roberts, Kevin E., E-mail: roberts29@llnl.gov [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94550 (United States); Allen, Patrick G., E-mail: allen42@llnl.gov [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94550 (United States); Shuh, David K., E-mail: dkshuh@lbl.gov [Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2017-07-15

    In contrast to UO{sub 2} and PuO{sub 2}, there is no consensus on the existence of mixed valence NpO{sub 2+x}, resulting in a gap between NpO{sub 2} and Np{sub 2}O{sub 5} (the highest binary oxide of Np) in the Np-O phase diagram. We now show NpO{sub 2+x} via Np L{sub III} Extended X-ray Absorption Fine Structure (EXAFS) spectra of three samples of NpO{sub 2} that, analogous to U and Pu, exhibit multisite Np-O distributions with varying numbers of oxygen atoms at 1.87–1.91 Å. This is supported by the diffraction pattern of the sample with the largest amount of this oxo-type species that can be refined with both the simple fluorite structure and a trigonal one related to α-U{sub 4}O{sub 9}. The implied Np(V)-bridging oxo moieties as well as possible indications of OH¯ found by detailed EXAFS analysis suggest that NpO{sub 2+x} more closely resembles PuO{sub 2+x} than UO{sub 2+x}. An additional common characteristic suggested by the EXAFS and X-Ray Diffraction (XRD) is the phase separation into NpO{sub 2} and what would be previously unreported Np{sub 4}O{sub 9(–δ)}, indicative of O clustering. - Graphical abstract: A reanalysis of the EXAFS of NpO{sub 2} finds a multisite Np-O distribution with Np(V)-oxo moieties at 1.88–1.91 Å. The structure and behavior of NpO{sub 2+x} more closely resemble PuO{sub 2+x} than UO{sub 2+x}.In addition EXAFS and XRD results indicate phase separation into NpO{sub 2} and previously unreported Np{sub 4}O{sub 9(–δ)}, signifying O clustering. - Highlights: •A reanalysis of XAFS data shows Np-oxo groups indicative of NpO{sub 2+x} in some samples. •Certain characteristics imply Np{sub 4}O{sub 9}, O clustering, and NpO{sub 2}:Np{sub 4}O{sub 9} phase separation. •Np(V) and other results indicate NpO{sub 2+x} resembles PuO{sub 2+x} more than UO{sub 2+x}. •Reanalysis of XRD data shows that the lattice constant Np{sub 4}O{sub 9} equals that of NpO{sub 2}.

  19. SolNet

    DEFF Research Database (Denmark)

    Jordan, Ulrike; Vajen, Klaus; Bales, Chris

    2014-01-01

    -accompanying Master courses, placements of internships, and PhD scholarship projects. A new scholarship project, “SHINE”, was launched in autumn 2013 in the frame work of the Marie Curie program of the European Union (Initial Training Network, ITN). 13 PhD-scholarships on solar district heating, solar heat......SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference...... for industrial processes, as well as sorption stores and materials started in December 2013. Additionally, the project comprises a training program with five PhD courses and several workshops on solar thermal engineering that will be open also for other PhD students working in the field. The research projects...

  20. Azeotropic distillation assisted fabrication of silver nanocages and their catalytic property for reduction of 4-nitrophenol.

    Science.gov (United States)

    Min, Jianzhong; Wang, Fei; Cai, Yunliang; Liang, Shuai; Zhang, Zhenwei; Jiang, Xingmao

    2015-01-14

    Monodisperse silver nanocages (AgNCs) with specific interiors were successfully synthesized by an azeotropic distillation (AD) assisted method and exhibited excellent catalytic activities for reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) due to the unique hollow morphology and small thickness of the silver shell.

  1. Reductive stripping of Np using a n-butyraldehyde from a loaded TBP phase containing Np

    International Nuclear Information System (INIS)

    Lee, Eil Hee; Lim, Jae Kwan; Chung, Dong Yong; Yang, Han Beom; Kim, Kwang Wook

    2008-01-01

    The reductive stripping of Np using a n-butyraldehyde (NBA) from loaded organic solution containing Np, which was oxidative-extracted in a system of a 30 % TBP/NDD-2M HNO 3 and O/A=2 containing 0.005 M K 2 Cr 2 O 7 as an oxidant of Np, was studied. The stripping yields of Np was increased with an increasing the NBA concentration, with a decreasing the nitric acid concentration of stripping solution and with a decreasing the reaction temperature. The apparent reductive stripping rate equation was shown by the following equation : -d [Np]-O-r-g/dt = 1,524 exp(-2,906/T) [NBA] 0.92 [Np] Org . At 1.04 M NBA and 2 M HNO 3 , the stripping yield of Np and U was 70.1 %, and 7.1 %, respectively, and the separation factor of U over Np (=D U /D Np ) was about 30.4. Therefore, it was found that U and Np co-extracted in a system of TBP-NHO 3 could be effectively mutual-separated by the NBA.

  2. 237 Np analytical method using 239 Np tracers and application to a contaminated nuclear disposal facility

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Mathew S.; Morrison, Samuel S.; Clark, Sue B.; Olson, John E.; Watrous, Matthew G.

    2017-06-01

    Environmental 237Np analyses are challenged by low 237Np concentrations and lack of an available yield tracer; we report a rapid, inexpensive 237Np analytical approach employing the short lived 239Np (t1/2 = 2.3 days) as a chemical yield tracer followed by 237Np quantification using inductively coupled plasma-mass spectrometry. 239Np tracer is obtained via separation from a 243Am stock solution and standardized using gamma spectrometry immediately prior to sample processing. Rapid digestions using a commercial, 900 watt “Walmart” microwave and Parr microwave vessels result in 99.8 ± 0.1% digestion yields, while chromatographic separations enable Np/U separation factors on the order of 106 and total Np yields of 95 ± 4% (2σ). Application of this method to legacy soil samples surrounding a radioactive disposal facility (the Subsurface Disposal Area at Idaho National Laboratory) reveal the presence of low level 237Np contamination within 600 meters of this site, with maximum 237Np concentrations on the order of 103 times greater than nuclear weapons testing fallout levels.

  3. 237Np analytical method using 239Np tracers and application to a contaminated nuclear disposal facility.

    Science.gov (United States)

    Snow, Mathew S; Morrison, Samuel S; Clark, Sue B; Olson, John E; Watrous, Matthew G

    2017-06-01

    Environmental 237 Np analyses are challenged by low 237 Np concentrations and lack of an available yield tracer; we report a rapid, inexpensive 237 Np analytical approach employing the short lived 239 Np (t 1/2  = 2.3 days) as a chemical yield tracer followed by 237 Np quantification using inductively coupled plasma-mass spectrometry. 239 Np tracer is obtained via separation from a 243 Am stock solution and standardized using gamma spectrometry immediately prior to sample processing. Rapid digestions using a commercial, 900 W "Walmart" microwave and Parr microwave vessels result in 99.8 ± 0.1% digestion yields, while chromatographic separations enable Np/U separation factors on the order of 10 6 and total Np yields of 95 ± 4% (2σ). Application of this method to legacy soil samples surrounding a radioactive disposal facility (the Subsurface Disposal Area at Idaho National Laboratory) reveal the presence of low level 237 Np contamination within 600 m of this site, with maximum 237 Np concentrations on the order of 10 3 times greater than nuclear weapons testing fallout levels. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Criticality of a 237Np sphere

    International Nuclear Information System (INIS)

    Sanchez, Rene G.; Loaiza, David J.; Kimpland, Robert H.; Hayes, David K.; Cappiello, Charlene C.; Myers, William L.; Jaegers, Peter J.; Clement, Steven D.; Butterfield, Kenneth B.

    2003-01-01

    A critical mass experiment using a 6-kg 237 Np sphere has been performed. The purpose of the experiment is to get a better estimate of the critical mass of 237 Np. To attain criticality, the 237 Np sphere was surrounded with 93 wt% 235 U shells. A 1/M as a function of uranium mass was performed. An MCNP neutron transport code was used to model the experiment. The MCNP code yielded a k eff of 0.99089 ± 0.0003 compared with a k eff 1.0026 for the experiment. Based on these results, it is estimated that the critical mass of 237 Np ranges from kilogram weights in the high fifties to low sixties. (author)

  5. COMPARISON OF SOL-GEL SILICATE COATINGS ON Ti SUBSTRATE

    Directory of Open Access Journals (Sweden)

    DIANA HORKAVCOVÁ

    2012-12-01

    Full Text Available The objective of the submitted work was to prepare and to characterize two types of silicate coatings prepared by the sol-gel method using the dip-coating technique on a titanium substrate. Efforts have been made to use mechanical properties of bio-inert titanium and bioactive properties of a silicate layer enriched with an admixture of compounds identified below. The first group consisted of silicate coatings containing silver, brushite and monetite. The other group of silicate coatings contained calcium nitrate and triethyl phosphate. Mechanically and chemically treated titanium substrates were dipped into sols and dried and fired. Silicate coatings from the first group were also chemically treated in 10 mol.l-1 solution of sodium hydroxide. All coatings were measured to determine their adhesive and bioactive properties and furthermore the antibacterial properties were tested in the case of first group. Surfaces of the coated substrates were investigated after the firing and after the individual tests with optical and electron microscopy and X-ray microdiffraction. A tape test demonstrated excellent adhesive property of all coatings to the substrate, classified with degree 5. A static in vitro test demonstrated bioactivity of nearly all the coatings. The basic silicate coating from the first group and one type of coating from the second group were identified as inert. Antibacterial properties of silicate coatings containing silver showed to be different when tested against Escherichia coli bacteria. A complete inhibition of the growth of bacteria under our experimental conditions was observed for the coating containing silver and monetite and a partial inhibition of the growth of bacteria for coatings containing silver and silver in combination with brushite.

  6. Mechanical and microstructural characterization of aluminum reinforced with carbon-coated silver nanoparticles

    International Nuclear Information System (INIS)

    Martinez-Sanchez, R.; Reyes-Gasga, J.; Caudillo, R.; Garcia-Gutierrez, D.I.; Marquez-Lucero, A.; Estrada-Guel, I.; Mendoza-Ruiz, D.C.; Jose Yacaman, M.

    2007-01-01

    Composites of pure aluminum with carbon-coated silver nanoparticles (Ag-C NP) of 10 nm in size were prepared by the mechanical milling process. Transmission electron microscopy showed that the Ag-C NP are homogeneously dispersed into the Al matrix, silver nanoparticles do not coalesce, grow or dissolve in the aluminum matrix due the carbon shell. The values of yield strength (σ y ), maximum strength (σ max ) and micro-hardness Vickers (HVN) of the composites were evaluated and reported as a function of Ag-C NP content. It has been found that the introduction of this type of particles in aluminum strengthen it, increasing all the previous parameters

  7. Np Analysis of Freshly Separated Material

    International Nuclear Information System (INIS)

    Hodge, Christopher A.

    2004-01-01

    Np analysis has historically relied upon the Pa/Np secular equilibrium for quantitative results. The Savannah River Site has recently undertaken a mission concerning Np. In this application, Np is separated from Pa, packaged, possibly mixed with other batches, and assayed. The fresh separation and mixing of batches prevents the use of the Pa133 prodigy peaks for assay. This effort was a developmental project novel in the DOE complex. This paper discusses the challenges encountered in the design of instrumentation to assay Np directly. The most abundant Np peak that is unfettered by Pa prodigy, Am, or other SNM materials is the 29.6keV. Quantitative measurement of such a low energy peak presents significant problems with attenuation, Compton effects, and other such issues that arise while trying to maximize the effects of low energy peaks. The solutions rely on exploiting the ''tried and true'' methods with regard to shielding, detector technology, and calibration techniques, but wit h a very low energy perspective. The results are intriguing and, with some assumptions regarding sample homogeneity, quantitative within normal MC and A statistics

  8. Biogenic antimicrobial silver nanoparticles produced by fungi.

    Science.gov (United States)

    Rodrigues, Alexandre G; Ping, Liu Yu; Marcato, Priscyla D; Alves, Oswaldo L; Silva, Maria C P; Ruiz, Rita C; Melo, Itamar S; Tasic, Ljubica; De Souza, Ana O

    2013-01-01

    Aspergillus tubingensis and Bionectria ochroleuca showed excellent extracellular ability to synthesize silver nanoparticles (Ag NP), spherical in shape and 35 ± 10 nm in size. Ag NP were characterized by transmission electron microscopy, X-ray diffraction analysis, and photon correlation spectroscopy for particle size and zeta potential. Proteins present in the fungal filtrate and in Ag NP dispersion were analyzed by electrophoresis (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Ag NP showed pronounced antifungal activity against Candida sp, frequently occurring in hospital infections, with minimal inhibitory concentration in the range of 0.11-1.75 μg/mL. Regarding antibacterial activity, nanoparticles produced by A. tubingensis were more effective compared to the other fungus, inhibiting 98.0 % of Pseudomonas. aeruginosa growth at 0.28 μg/mL. A. tubingensis synthesized Ag NP with surprisingly high and positive surface potential, differing greatly from all known fungi. These data open the possibility of obtaining biogenic Ag NP with positive surface potential and new applications.

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

    Science.gov (United States)

    Austin, Carlye Anne

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

  10. Silver nanoparticles: technological advances, societal impacts, and metrological challenges

    Science.gov (United States)

    Calderón-Jiménez, Bryan; Johnson, Monique E.; Montoro Bustos, Antonio R.; Murphy, Karen E.; Winchester, Michael R.; Vega Baudrit, José R.

    2017-02-01

    Silver nanoparticles (AgNPs) show different physical and chemical properties compared to their macroscale analogs. This is primarily due to their small size and, consequently, the exceptional surface area of these materials. Presently, advances in the synthesis, stabilization, and production of AgNPs have fostered a new generation of commercial products and intensified scientific investigation within the nanotechnology field. The use of AgNPs in commercial products is increasing and impacts on the environment and human health are largely unknown. This article discusses advances in AgNP production and presents an overview of the commercial, societal, and environmental impacts of this emerging nanoparticle (NP), and nanomaterials in general. Finally, we examine the challenges associated with AgNP characterization, discuss the importance of the development of NP reference materials (RMs) and explore their role as a metrological mechanism to improve the quality and comparability of NP measurements.

  11. Silver Nanoparticles: Technological Advances, Societal Impacts, and Metrological Challenges.

    Science.gov (United States)

    Calderón-Jiménez, Bryan; Johnson, Monique E; Montoro Bustos, Antonio R; Murphy, Karen E; Winchester, Michael R; Vega Baudrit, José R

    2017-01-01

    Silver nanoparticles (AgNPs) show different physical and chemical properties compared to their macroscale analogs. This is primarily due to their small size and, consequently, the exceptional surface area of these materials. Presently, advances in the synthesis, stabilization, and production of AgNPs have fostered a new generation of commercial products and intensified scientific investigation within the nanotechnology field. The use of AgNPs in commercial products is increasing and impacts on the environment and human health are largely unknown. This article discusses advances in AgNP production and presents an overview of the commercial, societal, and environmental impacts of this emerging nanoparticle (NP), and nanomaterials in general. Finally, we examine the challenges associated with AgNP characterization, discuss the importance of the development of NP reference materials (RMs) and explore their role as a metrological mechanism to improve the quality and comparability of NP measurements.

  12. Optical and structural studies of silver nanoparticles

    International Nuclear Information System (INIS)

    Temgire, M.K.; Joshi, S.S.

    2004-01-01

    Gamma radiolysis method was used to prepare polyvinyl alcohol (PVA) capped silver nanoparticles by optimizing various conditions like metal ion concentration and polymer (PVA) of different molecular weights. The role of different scavengers was also studied. The decrease in particle size was observed with increase in the molecular weight of capping agent. γ-radiolytic method provides silver nanoparticles in fully reduced and highly pure state. XRD (X-ray diffraction) technique confirmed the zero valent state of silver. Optical studies were done using UV-visible spectrophotometer to see the variation of electronic structure of the metal sol. Transmission Electron Microscopic (TEM) studies reveal the fcc geometry. The TEM show clearly split Debye-Scherrer rings. The d values calculated from the diffraction ring pattern are in perfect agreement with the ASTM data. Ag particles less than 10 nm are spherical in shape, whereas the particles above 30 nm have structure of pentagonal biprisms or decahedra, referred to as multiply twinned particles

  13. Silver linings.

    Science.gov (United States)

    Bultas, Margaret W; Pohlman, Shawn

    2014-01-01

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

  14. Thoria sol-gel processes

    International Nuclear Information System (INIS)

    Matthews, R.B.

    1978-10-01

    Alternate fuel fabrication techniques are being developed at WNRE as part of the thorium fuel cycle program. The sol-gel techniques are attractive and this report assembles and summarizes information relating to thoria sol-gel fuels. Some background information on the behaviour and advantages of sol-gel fuel forms is presented, followed by a review of relevant colloid chemistry and an explanation of the fundamental steps of sol-gel processes. Finally, several variants to the basic process are reviewed and evaluated. (author)

  15. Aggregation and dissolution of silver nanoparticles in a laboratory-based freshwater microcosm under simulated environmental conditions

    CSIR Research Space (South Africa)

    Walters, Chavon R

    2014-04-01

    Full Text Available CSIR, Natural Resources and the Environment, Stellenbosch, South Africa; bDepartment of Medical Biosciences, University of the Western Cape, Bellville, South Africa Abstract Silver nanoparticles (NP) are used in several applications, including their use...

  16. Toxicity of silver nanoparticles in zebrafish models

    Energy Technology Data Exchange (ETDEWEB)

    Asharani, P V; Valiyaveettil, Suresh [Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, 117543 (Singapore); Wu Yilian; Gong Zhiyuan [Department of Biological Sciences, National University of Singapore, Science Drive 4, 117543 (Singapore)], E-mail: chmsv@nus.edu.sg

    2008-06-25

    This study was initiated to enhance our insight on the health and environmental impact of silver nanoparticles (Ag-np). Using starch and bovine serum albumin (BSA) as capping agents, silver nanoparticles were synthesized to study their deleterious effects and distribution pattern in zebrafish embryos (Danio rerio). Toxicological endpoints like mortality, hatching, pericardial edema and heart rate were recorded. A concentration-dependent increase in mortality and hatching delay was observed in Ag-np treated embryos. Additionally, nanoparticle treatments resulted in concentration-dependent toxicity, typified by phenotypes that had abnormal body axes, twisted notochord, slow blood flow, pericardial edema and cardiac arrhythmia. Ag{sup +} ions and stabilizing agents showed no significant defects in developing embryos. Transmission electron microscopy (TEM) of the embryos demonstrated that nanoparticles were distributed in the brain, heart, yolk and blood of embryos as evident from the electron-dispersive x-ray analysis (EDS). Furthermore, the acridine orange staining showed an increased apoptosis in Ag-np treated embryos. These results suggest that silver nanoparticles induce a dose-dependent toxicity in embryos, which hinders normal development.

  17. Toxicity of silver nanoparticles in zebrafish models

    International Nuclear Information System (INIS)

    Asharani, P V; Valiyaveettil, Suresh; Wu Yilian; Gong Zhiyuan

    2008-01-01

    This study was initiated to enhance our insight on the health and environmental impact of silver nanoparticles (Ag-np). Using starch and bovine serum albumin (BSA) as capping agents, silver nanoparticles were synthesized to study their deleterious effects and distribution pattern in zebrafish embryos (Danio rerio). Toxicological endpoints like mortality, hatching, pericardial edema and heart rate were recorded. A concentration-dependent increase in mortality and hatching delay was observed in Ag-np treated embryos. Additionally, nanoparticle treatments resulted in concentration-dependent toxicity, typified by phenotypes that had abnormal body axes, twisted notochord, slow blood flow, pericardial edema and cardiac arrhythmia. Ag + ions and stabilizing agents showed no significant defects in developing embryos. Transmission electron microscopy (TEM) of the embryos demonstrated that nanoparticles were distributed in the brain, heart, yolk and blood of embryos as evident from the electron-dispersive x-ray analysis (EDS). Furthermore, the acridine orange staining showed an increased apoptosis in Ag-np treated embryos. These results suggest that silver nanoparticles induce a dose-dependent toxicity in embryos, which hinders normal development

  18. TiO2/SiO2 prepared via facile sol-gel method as an ideal support for green synthesis of Ag nanoparticles using Oenothera biennis extract and their excellent catalytic performance in the reduction of 4-nitrophenol

    Directory of Open Access Journals (Sweden)

    Bahar Khodadadi

    2017-01-01

    Full Text Available In the present study, the extract of the plant of Oenothera biennis was used to green synthesis of silver nanoparticles (Ag NPs as an environmentally friendly, simple and low cost method. And Additionally, TiO2/SiO2 was prepared via facile sol-gel method using starch as an important, naturally abundant organic polymer as an ideal support. The Ag NPs/TiO2/SiO2 as an effective catalyst was prepared through reduction of Ag+ ions using Oenothera biennis extract as the reducing and stabilizing agent and Ag NPs immobilization on TiO2/SiO2 surface in the absence of any stabilizer or surfactant. Several techniques such as FT-IR spectroscopy, UV-Vis spectroscopy, X-ray Diffraction (XRD, sScanning eElectron mMicroscopy (FE-SEM, Eenergy dDispersive X-ray sSpectroscopy (EDS, and Ttransmission Eelectron Mmicroscopy (TEM were used to characterize TiO2/SiO2, silver nanoparticles (Ag NPs, and Ag NPs/TiO2/SiO2. Moreover, the catalytic activity of the Ag NPs/ TiO2/SiO2 was investigated in the reduction of 4-nitrophenol (4-NP at room temperature. On the basis of the results, the Ag NPs/TiO2/SiO2 was found to be high catalytic activity highly active catalyst according to the experimental results in this study. In addition, Ag NPs/TiO2/SiO2 can be recovered and reused several times in the reduction of 4-NP with no significant loss of catalytic activity.

  19. Neutron Data Evaluation of 237Np

    International Nuclear Information System (INIS)

    Maslov, V.M.; Tetereva, N.A.; Kolesov, A.M.; Pronyaev, V.G.; Zolotarev, K.I.; Granier, T.; Hambsch, F.-J.

    2010-11-01

    The diverse measured data base of n+ 237 Np was evaluated using a statistical theory and generalized least squares codes. Consistent description of the total, fission and partial inelastic scattering data in 1-3 MeV energy range provides an important constraint for the absorption cross section, which is quite important for the robust estimate of the capture cross section in the 0.5-500 keV energy range. Important constraints for the measured capture cross section come from the average radiative S0 and S1 strength functions. The evaluated inelastic cross sections of available evaluations are in severe disagreement with measured data on the inelastic scattering of neutrons with excitation of specific groups of levels. A change of the inelastic data shape at E n ∼1.5 MeV might be explained by the sharp increase of the level density of the residual odd-even nuclide 237 Np due to the onset of three-quasi-particle excitations. The influence of exclusive (n, xnf) pre-fission neutrons on prompt fission neutron spectra (PFNS) and (n, xn) spectra is modeled. Contributions of emissive/non-emissive fission and exclusive spectra of (n, xnf) reactions are defined by a consistent description of the 237 Np (n, F), 237 Np (n, 2n) 236s Np reactions and the ratio of the yields of short-lived (1 - ) and long-lived (6 - ) 236 Np states measured at 14 MeV. Excited levels of 236 Np are modeled using predicted Gallher-Moshkowski doublets. This work is performed under the project Agreement B-1604 with the International Science and Technology Center (Moscow). The financing party is EU. Partial support of International Atomic Energy Agency under Research Contract 14809 is acknowledged by JINER. (author)

  20. Effects of silver nanoparticles (NM-300K) on Lumbricus rubellus earthworms and particle characterization in relevant test matrices including soil

    NARCIS (Netherlands)

    Ploeg, M.J.C. van der; Handy, R.D.; Waalewijn-Kool, P.L.; Berg, J.H.J. van den; Herrera Rivera, Z.E.; Bovenschen, J.; Molleman, B.; Baveco, J.M.; Tromp, P.; Peters, R.J.B.; Koopmans, G.F.; Rietjens, I.M.C.M.; Brink, N.W. van den

    2014-01-01

    The impact of silver nanoparticles (AgNP; at 0mg Ag/kg, 1.5mg Ag/kg, 15.4mg Ag/kg, and 154mg Ag/kg soil) and silver nitrate (AgNO3; 15.4mg Ag/kg soil) on earthworms, Lumbricus rubellus, was assessed. A 4-wk exposure to the highest AgNP treatment reduced growth and reproduction compared with the

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

    Directory of Open Access Journals (Sweden)

    D. Tomacheski

    2017-12-01

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

  2. Np(V)/Np(IV) in concentrated carbonate/bicarbonate solutions; Np(V)/Np(IV) en solutions carbonate/bicarbonate concentrees

    Energy Technology Data Exchange (ETDEWEB)

    Delmau, L.H.; Vitorge, P.; Capdevila, H.

    1996-01-01

    A 1.5 M Na{sub 2}CO{sub 3} solution of Np(V) is electrolysed to Np(IV) at -2.0 V/SHE. -1g(H{sup +}) is decreased from 10.4 to 7.2 by bubbling CO{sub 2} in these solutions, where Np(IV) spectra can be interpreted with the only lost of one CO{sub 3}{sup 2-} anion from the Np(IV) limiting complex. From these spectral changes, the following parameters are fitted: 20.5 {+-} 2.1, 8.44 {+-} 0.9 and 28.9 {+-} 2.9 l/mol./cm for the Np(CO{sub 3}){sub 5}{sup 6-} molar absorptivity at 823, 990 and 1013 nm respectively, and 54.5 {+-} 5.5, 40.6 {+-} 4.1 and 8.53 {+-} 0.9 for the Np(CO{sub 3}){sub 4}{sup 4-} ones, and log((Np(CO{sub 3}){sub 5}{sup 6-}) / ((Np(CO{sub 3}){sub 4}{sup 4-})(CO{sub 3}{sup 2-}))) = 1.47 {+-} 0.08, 1.63 {+-} 0.05, 1.80 {+-} 0.04, 1.79 {+-} 0.10 and 2.21 {+-} 0.03 at the half point reaction in initially 0.2, 0.3, 0.4, 0.5 and 0.6 M Na{sub 2}CO{sub 3} solutions. These values are extrapolated to 0 ionic strength by using the Specific Interaction Theory (SIT). The redox potential of 0.3, 0.6, 1 and 1.5 M Na{sub 2}CO{sub 3} solutions of Np(V) and Np(IV) mixtures, is stable usually after three hours at T from 5 to 60 deg C, and then for up to three weeks at 21.5 deg C. At 25 deg C, its values are 0.247, 0.234, 0.244 and 0.228 V/SEH in 0.3, 0.6, 1 and 1.5 M Na{sub 2}CO{sub 3} solutions. When the tonic strength is equal to 0: E = 0.52 {+-} 0.1 V/SEH and {Delta}S/F = -1.1 {+-} 0.7 mV. deg C{sup -1}. Assuming this potential is controlled by the NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-} + 2 CO{sub 2} + e{sup -} {r_reversible} Np(CO{sub 3}){sub 5}{sup 6-} equilibrium, the formation constant of the limiting complex is deduced by using published values of the other needed equilibria: log {Beta}{sub 5}{sup d}eg = 38 {+-} 4. Qualitative results on the preparation and on the spectra of Np(IV) are used to explain the apparent contradictions between some published results. (authors). 39 refs., figs., tabs.

  3. Np(V) and Np(VI) in bicarbonate/carbonate aqueous solutions

    International Nuclear Information System (INIS)

    Vitorge, P.; Capdevila, H.

    1998-01-01

    Formation constants for NpO 2 (CO 3 ) i l2i (i = 1, 2 and 3), NaNpO 2 CO 3(s) and Na 3 NpO 2 (CO 3 ) 2(s) are deduced from Simakin's et al. (1977), Maya's (1983), and Vitorge's et al. data, who also found evidence for a mixed Np(V)-OH-CO 3 soluble complex. Simakin (1977) found NpO 2 (CO 3 ) 3 -4 , it was confirmed by Riglet (1989), and by Offerle, Capdevilla and Vittorge (1995). Temperature influence was studied by Ullman and Schreiner (1988), and by Offerle, Capdevila and Vittorge (1995). Grenthe, Riglet and Vitorge (1986 and 1989) proved the existence of the trinuclear species (NpO 2 ) 3 (CO 3 ) 6 -6 . Maya (1984) mis-interpreted his data; nevertheless they show evidence of a new polynuclear mixed species, certainly (NpO 2 ) 2 (OH) 3 CO 3 -1 , as initially proposed by Maya. No other Np(V) or Np(VI) soluble complex could be detected, the proposed ones quantitatively account for all published works. Unpublished data allowed to estimate the stability of intermediary mononuclear complexes and NpO 2 CO 3(s) solubility product. M 4 NpO 2 (CO 3 ) 3(s) (M + = K + or NH 4 + ) ones are deduced from Gorbenko-Germanov and Klimov (1966), and Moskvin (1975) data as respectively interpreted and reinterpreted by this review. Thermodynamic data determined in this report are under discussion within OECD-NEA-TDB. (author)

  4. Solubility studies of Np(IV)

    International Nuclear Information System (INIS)

    Zhang Yingjie; Yao Jun; Jiao Haiyang; Ren Lihong; Zhou Duo; Fan Xianhua

    2001-01-01

    The solubility of Np(IV) in simulated underground water and redistilled water has been measured with the variations of pH(6-12) and storage time (0-100 d) in the presence of reductant (Na 2 S 2 O 4 , metallic Fe). All experiments are performed in a low oxygen concentration glove box containing high purity Ar(99.99%), with an oxygen content of less than 5 x 10 -6 mol/mol. Experimental results show that the variation of pH in solution has little effect on the solubility of Np(IV) in the two kinds of water; the measured solubility of Np(IV) is affected by the composition of solution; with Na 2 S 2 O 4 as a reductant, the solubility of Np(IV) in simulated underground water is (9.23 +- 0.48) x 10 -10 mol/L, and that in redistilled water is (8.31 +- 0.35) x 10 -10 mol/L; with metallic Fe as a reductant, the solubility of Np(IV) in simulated underground water is (1.85 +- 0.56) x 10 -9 mol/L, and that in redistilled water is (1.48 +- 0.66) x 10 -9 mol/L

  5. Synthesis and Characterization of Silver Nanoparticles for an Undergraduate Laboratory

    Science.gov (United States)

    Orbaek, Alvin W.; McHale, Mary M.; Barron, Andrew R.

    2015-01-01

    The aim of this simple, quick, and safe laboratory exercise is to provide undergraduate students an introduction to nanotechnology using nanoparticle (NP) synthesis. Students are provided two procedures that allow for the synthesis of different yet controlled sizes of silver NPs. After preparing the NPs, the students perform UV-visible…

  6. Nanocrystal/sol-gel nanocomposites

    Science.gov (United States)

    Petruska, Melissa A [Los Alamos, NM; Klimov, Victor L [Los Alamos, NM

    2007-06-05

    The present invention is directed to solid composites including colloidal nanocrystals within a sol-gel host or matrix and to processes of forming such solid composites. The present invention is further directed to alcohol soluble colloidal nanocrystals useful in formation of sol-gel based solid composites.

  7. Soil contamination with silver nanoparticles reduces Bishop pine growth and ectomycorrhizal diversity on pine roots

    Energy Technology Data Exchange (ETDEWEB)

    Sweet, M. J., E-mail: m.sweet@derby.ac.uk [University of Derby, Environmental Sustainability Research Centre, College of Life and Natural Sciences (United Kingdom); Singleton, I. [Newcastle University, School of Biology (United Kingdom)

    2015-11-15

    Soil contamination by silver nanoparticles (AgNP) is of potential environmental concern but little work has been carried out on the effect of such contamination on ectomycorrhizal fungi (EMF). EMF are essential to forest ecosystem functions as they are known to enhance growth of trees by nutrient transfer. In this study, soil was experimentally contaminated with AgNP (0, 350 and 790 mg Ag/kg) and planted with Bishop pine seedlings. The effect of AgNP was subsequently measured, assessing variation in pine growth and ectomycorrhizal diversity associated with the root system. After only 1 month, the highest AgNP level had significantly reduced the root length of pine seedlings, which in turn had a small effect on above ground plant biomass. However, after 4 months growth, both AgNP levels utilised had significantly reduced both pine root and shoot biomass. For example, even the lower levels of AgNP (350 mg Ag/kg) soil, reduced fresh root biomass by approximately 57 %. The root systems of the plants grown in AgNP-contaminated soils lacked the lateral and fine root development seen in the control plants (no AgNP). Although, only five different genera of EMF were found on roots of the control plants, only one genus Laccaria was found on roots of plants grown in soil containing 350 mg AgNP/kg. At the higher levels of AgNP contamination, no EMF were observed. Furthermore, extractable silver was found in soils containing AgNP, indicating potential dissolution of silver ions (Ag+) from the solid AgNP.

  8. Soil contamination with silver nanoparticles reduces Bishop pine growth and ectomycorrhizal diversity on pine roots

    International Nuclear Information System (INIS)

    Sweet, M. J.; Singleton, I.

    2015-01-01

    Soil contamination by silver nanoparticles (AgNP) is of potential environmental concern but little work has been carried out on the effect of such contamination on ectomycorrhizal fungi (EMF). EMF are essential to forest ecosystem functions as they are known to enhance growth of trees by nutrient transfer. In this study, soil was experimentally contaminated with AgNP (0, 350 and 790 mg Ag/kg) and planted with Bishop pine seedlings. The effect of AgNP was subsequently measured, assessing variation in pine growth and ectomycorrhizal diversity associated with the root system. After only 1 month, the highest AgNP level had significantly reduced the root length of pine seedlings, which in turn had a small effect on above ground plant biomass. However, after 4 months growth, both AgNP levels utilised had significantly reduced both pine root and shoot biomass. For example, even the lower levels of AgNP (350 mg Ag/kg) soil, reduced fresh root biomass by approximately 57 %. The root systems of the plants grown in AgNP-contaminated soils lacked the lateral and fine root development seen in the control plants (no AgNP). Although, only five different genera of EMF were found on roots of the control plants, only one genus Laccaria was found on roots of plants grown in soil containing 350 mg AgNP/kg. At the higher levels of AgNP contamination, no EMF were observed. Furthermore, extractable silver was found in soils containing AgNP, indicating potential dissolution of silver ions (Ag+) from the solid AgNP

  9. A versatile synthesis of highly bactericidal Myramistin (registered) stabilized silver nanoparticles

    International Nuclear Information System (INIS)

    Vertelov, G K; Krutyakov, Yu A; Olenin, A Yu; Lisichkin, G V; Efremenkova, O V

    2008-01-01

    Silver nanoparticles stabilized by a well-known antibacterial surfactant benzyldimethyl[3-(myristoylamino)propyl]ammonium chloride (Myramistin) were produced for the first time by borohydride reduction of silver chloride sol in water. Stable aqueous dispersions of silver nanoparticles without evident precipitation for several months could be obtained. In vitro bactericidal tests showed that Myramistin capped silver NPs exhibited notable activity against six different microorganisms-gram-positive and gram-negative bacteria, yeasts and fungi. The activity was up to 20 times higher (against E. coli) compared to Myramistin at the same concentrations and on average 2 times higher if compared with citrate-stabilized NPs

  10. A versatile synthesis of highly bactericidal Myramistin® stabilized silver nanoparticles

    Science.gov (United States)

    Vertelov, G. K.; Krutyakov, Yu A.; Efremenkova, O. V.; Olenin, A. Yu; Lisichkin, G. V.

    2008-09-01

    Silver nanoparticles stabilized by a well-known antibacterial surfactant benzyldimethyl[3-(myristoylamino)propyl]ammonium chloride (Myramistin®) were produced for the first time by borohydride reduction of silver chloride sol in water. Stable aqueous dispersions of silver nanoparticles without evident precipitation for several months could be obtained. In vitro bactericidal tests showed that Myramistin® capped silver NPs exhibited notable activity against six different microorganisms—gram-positive and gram-negative bacteria, yeasts and fungi. The activity was up to 20 times higher (against E. coli) compared to Myramistin® at the same concentrations and on average 2 times higher if compared with citrate-stabilized NPs.

  11. Chemical aspects of 237 Np Moessbauer spectroscopy

    International Nuclear Information System (INIS)

    Karraker, D.G.

    1984-01-01

    The 237 Np Moessbauer effect has been especially useful in studies of neptunium chemistry, by virtue of its excellent resolution and straightforward experimental techniques. Neptunium can have valences from +3 to +7, and a broad range of compounds can be prepared that are analogous to those of other actinide elements. Studies on neptunium compounds, for example, have a ready application to the analogous compounds of uranium and plutonium. The emphasis in this paper will be on the application of the 237 Np Moessbauer effect to problems in neptunium chemistry

  12. Silver nanoprisms self-assembly on differently functionalized silica surface

    International Nuclear Information System (INIS)

    Pilipavicius, J; Chodosovskaja, A; Beganskiene, A; Kareiva, A

    2015-01-01

    In this work colloidal silica/silver nanoprisms (NPRs) composite coatings were made. Firstly colloidal silica sols were synthesized by sol-gel method and produced coatings on glass by dip-coating technique. Next coatings were silanized by (3-Aminopropyl)triethoxysilane (APTES), N-[3-(Trimethoxysilyl)propyl]ethylenediamine (AEAPTMS), (3- Mercaptopropyl)trimethoxysilane (MPTMS). Silver NPRs where synthesized via seed-mediated method and high yield of 94±15 nm average edge length silver NPRs were obtained with surface plasmon resonance peak at 921 nm. Silica-Silver NPRs composite coatings obtained by selfassembly on silica coated-functionalized surface. In order to find the most appropriate silanization way for Silver NPRs self-assembly, the composite coatings were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), water contact angle (CA) and surface free energy (SFE) methods. Results have showed that surface functionalization is necessary to achieve self-assembled Ag NPRs layer. MPTMS silanized coatings resulted sparse distribution of Ag NPRs. Most homogeneous, even distribution composite coatings obtained on APTES functionalized silica coatings, while AEAPTMS induced strong aggregation of Silver NPRs

  13. Influence of silver nanoparticles on growth and health of broiler chickens after infection with Campylobacter jejuni

    DEFF Research Database (Denmark)

    Vadalasetty, Krishna Prasad; Lauridsen, Charlotte; Engberg, Ricarda Margarete

    2018-01-01

    Background Silver nanoparticles (AgNP) have gained much attention in recent years due to their biomedical applications, especially as antimicrobial agents. AgNP may be used in poultry production as an alternative to the use of antibiotic growth promoter. However, little is known about the impact...

  14. Russell-Silver syndrome

    Science.gov (United States)

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

  15. Np-237 in peat and lichen in Finland

    DEFF Research Database (Denmark)

    Salminen, S.; Paatero, J.; Roos, Per

    2009-01-01

    Activity concentrations of 237Np in peat and lichen samples in Finland were determined and contributions from nuclear weapons testing in 1950–1960s and the Chernobyl accident were estimated. 237Np was determined with ICP-MS using 235Np as a tracer. Activity concentrations of 237Np in peat samples...

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

    Directory of Open Access Journals (Sweden)

    Cassandra E. Nix

    2018-05-01

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

  17. Resolved resonance parameters for 236Np

    International Nuclear Information System (INIS)

    Morogovskij, G.B.; Bakhanovich, L.A.

    2002-01-01

    Multilevel Breit-Wigner parameters were obtained for fission cross-section representation in the 0.01-33 eV energy region from evaluation of a 236 Np experimental fission cross-section in the resolved resonance region. (author)

  18. Computing quantum discord is NP-complete

    International Nuclear Information System (INIS)

    Huang, Yichen

    2014-01-01

    We study the computational complexity of quantum discord (a measure of quantum correlation beyond entanglement), and prove that computing quantum discord is NP-complete. Therefore, quantum discord is computationally intractable: the running time of any algorithm for computing quantum discord is believed to grow exponentially with the dimension of the Hilbert space so that computing quantum discord in a quantum system of moderate size is not possible in practice. As by-products, some entanglement measures (namely entanglement cost, entanglement of formation, relative entropy of entanglement, squashed entanglement, classical squashed entanglement, conditional entanglement of mutual information, and broadcast regularization of mutual information) and constrained Holevo capacity are NP-hard/NP-complete to compute. These complexity-theoretic results are directly applicable in common randomness distillation, quantum state merging, entanglement distillation, superdense coding, and quantum teleportation; they may offer significant insights into quantum information processing. Moreover, we prove the NP-completeness of two typical problems: linear optimization over classical states and detecting classical states in a convex set, providing evidence that working with classical states is generically computationally intractable. (paper)

  19. Autoionizing np Rydberg states of H2

    International Nuclear Information System (INIS)

    Xu, E.Y.; Helm, H.; Kachru, R.

    1989-01-01

    We report a study of the autoionizing np Rydberg states near the lowest ionization threshold of H 2 . Using resonant two-photon excitation, intermediate states in specific rotovibrational levels in the double well, E,F 1 Σ/sub g/ + states are prepared. Then, a second, tunable laser is used to photoionize via excitation of the np Rydberg states. Because of the stepwise laser excitation scheme employed in our experiment the photoionization occurs from states with vibrational wave functions very similar to those of the H 2 + core. As a consequence, the autoionizing states appear as nearly symmetric resonances, rather than the highly asymmetric Beutler-Fano profiles observed from the direct photoexcitation from the ground state of H 2 . Our experiments show that the J = 1 np states are broader than the J = 3 np states converging to the same limit, suggesting that the two states autoionize into the epsilon-cp and epsilon-cf continuum, respectively. We compare our observations with a theoretical analysis using a multichannel quantum defect theory. The J = 1 states reveal the profound effect caused by the perturbation of the autoionizing Rydberg series converging to the lowest vibrational and rotational state of H 2 + by low-n states converging to higher vibrational states of the H 2 -ion core

  20. Aspartame-stabilized gold-silver bimetallic biocompatible nanostructures with plasmonic photothermal properties, antibacterial activity, and long-term stability.

    Science.gov (United States)

    Fasciani, Chiara; Silvero, M Jazmin; Anghel, Maria Alexandra; Argüello, Gerardo A; Becerra, Maria Cecilia; Scaiano, Juan C

    2014-12-17

    Gold-silver core-shell nanoparticles stabilized with a common sweetener, aspartame (AuNP@Ag@Asm), combine the antimicrobial properties of silver with the photoinduced plasmon-mediated photothermal effects of gold. The particles were tested with several bacterial strains, while biocompatibility was verified with human dermal fibroblasts.

  1. Evaluation of methods for retention of radioiodine during processing of irradiated 237Np

    International Nuclear Information System (INIS)

    Thompson, G.H.; Kelley, J.A.

    1975-06-01

    Methods of removing radioiodine from 237 Np-- 238 Pu dissolver solution and process off-gas were investigated. This program is part of a continuing effort to reduce releases of radionuclides from plant operations. Experimental data show: Greater than 99.9 percent of the radioiodine in dissolver solution can be removed by precipitation, in situ, of manganese dioxide. Silver zeolite will sorb greater than 99.9 percent of radioiodine in process off-gas. Other solid sorbents and nitric acid-mercuric nitrate scrubber solutions do not remove appreciable amounts of radioiodine from process off-gas, because radioiodine is present principally as relatively unreactive organic iodine compounds. (U.S.)

  2. Synthesis of silver nano-materials from Grevillea robusta A Cunn (Silver-oak tree) leaves extract and shape directing role of cetyltrimethylammonium bromide

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Rabia; Faisal, Qamer; Hussain, Sajjad [Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi-110025 (India)

    2016-05-23

    Grevillea robusta (Silver-oak tree) tree is a medicinal tree. Conventional UV-visible spectrophotometric and transmission electron microscopic technique were used to determine the morphology of silver nanoplates (AgNP) using Grevillea robusta (Silver-oak tree) aqueous leaves extract for the first time. The visible spectra showed the presence of three well defined surface plasmon absorption (SPR) bands at 500, 550 and 675 nm which was attributed to the anisotropic growth of Ag-nanoplates. Transmission electron microscopic (TEM) analysis of AgNP showed formation of truncated triangular, polyhedral with some irregular shapes nanoplates in the size range 8-20 nm. Cetyltrimethylammonium bromide (CTAB) has no significant effect on the shape of the spectra, position of SPR bands, size and size distribution of AgNP.

  3. Synthesis of silver nano-materials from Grevillea robusta A Cunn (Silver-oak tree) leaves extract and shape directing role of cetyltrimethylammonium bromide

    International Nuclear Information System (INIS)

    Ahmad, Rabia; Faisal, Qamer; Hussain, Sajjad

    2016-01-01

    Grevillea robusta (Silver-oak tree) tree is a medicinal tree. Conventional UV-visible spectrophotometric and transmission electron microscopic technique were used to determine the morphology of silver nanoplates (AgNP) using Grevillea robusta (Silver-oak tree) aqueous leaves extract for the first time. The visible spectra showed the presence of three well defined surface plasmon absorption (SPR) bands at 500, 550 and 675 nm which was attributed to the anisotropic growth of Ag-nanoplates. Transmission electron microscopic (TEM) analysis of AgNP showed formation of truncated triangular, polyhedral with some irregular shapes nanoplates in the size range 8-20 nm. Cetyltrimethylammonium bromide (CTAB) has no significant effect on the shape of the spectra, position of SPR bands, size and size distribution of AgNP.

  4. Size-tunable silver nanoparticles synthesized by using aminopolycarboxylic acids at ambient-temperature

    International Nuclear Information System (INIS)

    Malkar, Vishwabharati V.; Chadha, R.; Biswas, N.; Mukherjee, T.; Kapoor, S.

    2009-01-01

    Full text: Stable aqueous sols of silver nanoparticles are prepared by using various aminopolycarboxylic acids as stabilizing agents at ambient temperature. The precursor silver perchlorate is reduced using γ radiations. Interestingly, it was observed that size of silver nanoparticles obtained could be tuned using various aminopolycarboxylic acids of varying carboxylic acid groups The silver sols synthesized by this method were stable for months and particles obtained were monodisperse in almost all cases. Particle formation was observed at equimolar concentration of silver and aminopolycarboxylic acids. The stabilization of particles even in the absence of any polymer indicates that the adsorption of aminopolycarboxylic acids on silver particle is a spontaneous process. The adsorbed aminopolycarboxylic acids can saturate the residual valence force of the silver atom on the particle surface by coordinating with unoccupied orbital. Adsorption of aminopolycarboxylic acids does not lead to any change in surface plasmon band of silver nanoparticles; this indicates that anions in the double layer on the colloidal particle have different chemical properties from the free anions. Synthesized silver nanoparticles were characterized by UV-visible spectrophotometer, X-ray Diffraction, Dynamic Light Scattering and Transmission Electron Microscope

  5. Incorporation of silver nanoparticles on the surface of orthodontic microimplants to achieve antimicrobial properties

    Science.gov (United States)

    Venugopal, Adith; Muthuchamy, Nallal; Tejani, Harsh; Gopalan, Anantha-Iyengar; Lee, Kwang-Pill; Lee, Heon-Jin

    2017-01-01

    Objective Microbial aggregation around dental implants can lead to loss/loosening of the implants. This study was aimed at surface treating titanium microimplants with silver nanoparticles (AgNPs) to achieve antibacterial properties. Methods AgNP-modified titanium microimplants (Ti-nAg) were prepared using two methods. The first method involved coating the microimplants with regular AgNPs (Ti-AgNP) and the second involved coating them with a AgNP-coated biopolymer (Ti-BP-AgNP). The topologies, microstructures, and chemical compositions of the surfaces of the Ti-nAg were characterized by scanning electron microscopy (SEM) equipped with energy-dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). Disk diffusion tests using Streptococcus mutans, Streptococcus sanguinis, and Aggregatibacter actinomycetemcomitans were performed to test the antibacterial activity of the Ti-nAg microimplants. Results SEM revealed that only a meager amount of AgNPs was sparsely deposited on the Ti-AgNP surface with the first method, while a layer of AgNP-coated biopolymer extended along the Ti-BP-AgNP surface in the second method. The diameters of the coated nanoparticles were in the range of 10 to 30 nm. EDS revealed 1.05 atomic % of Ag on the surface of the Ti-AgNP and an astounding 21.2 atomic % on the surface of the Ti-BP-AgNP. XPS confirmed the metallic state of silver on the Ti-BP-AgNP surface. After 24 hours of incubation, clear zones of inhibition were seen around the Ti-BP-AgNP microimplants in all three test bacterial culture plates, whereas no antibacterial effect was observed with the Ti-AgNP microimplants. Conclusions Titanium microimplants modified with Ti-BP-AgNP exhibit excellent antibacterial properties, making them a promising implantable biomaterial. PMID:28127534

  6. Pyrene As a New Detector for Determining the Composition of Silver Nanoparticle Dispersions in Aqueous Solutions

    Science.gov (United States)

    Romanovskaya, G. I.; Kazakova, S. Yu.; Koroleva, M. V.; Zuev, B. K.

    2018-03-01

    It is proposed that the fluorescence of monomeric molecules of pyrene in solid matrices or in concentrated micellar solutions be used as a detector for determining the compositional homogeneity of silver nanoparticle (NP) dispersions in aqueous solutions synthesized in different ways. It is found that the morphology of silver NPs affects the change in the fluorescence intensity of monomeric molecules of pyrene in a certain (violet or blue) region of the pyrene optical spectrum. The observed phenomenon is attributed to the resonance of electronic transitions in the monomeric molecules of pyrene in regions with plasmon oscillations in silver nanoparticles. A new way of obtaining fluorescent silver NPs is found.

  7. Silver sulfide nanoparticle assembly obtained by reacting an assembled silver nanoparticle template with hydrogen sulfide gas.

    Science.gov (United States)

    Chen, Rui; Nuhfer, Noel T; Moussa, Laura; Morris, Hannah R; Whitmore, Paul M

    2008-11-12

    A fast, simple procedure is described for obtaining an assembly of silver sulfide nanoparticles (Ag(2)S NPs) on a glass substrate through reaction of a template of an assembled layer of silver nanoparticles (Ag NPs) with hydrogen sulfide (H(2)S) gas. The Ag NP template was prepared by assembling a monolayer of spherical Ag NPs (mean diameter of 7.4 nm) on a polyethylenimine-treated glass substrate. Exposure to pure H(2)S for 10 min converted the Ag NPs of the template to Ag(2)S NPs. The resulting Ag(2)S NP assembly, which retains the template nanostructure and particle distribution, was characterized by optical absorption spectroscopy, atomic force microscopy, transmission electron microscopy (TEM), scanning high resolution TEM, energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The Ag(2)S NPs have a crystal structure of monoclinic acanthite, and while they retained the spherical shape of the original Ag NPs, their mean particle size increased to 8.4 nm due to changes to the crystal structure when the Ag NPs are converted into Ag(2)S NPs. The measured optical absorption edge of the Ag(2)S NP assembly indicated an indirect interband transition with a band gap energy of 1.71 eV. The Ag(2)S NP assembly absorbed light with wavelengths below 725 nm, and the absorbance increased monotonically toward the UV region.

  8. Biological Mechanism of Silver Nanoparticle Toxicity

    Science.gov (United States)

    Armstrong, Najealicka Nicole

    Silver nanoparticles (AgNPs), like almost all nanoparticles, are potentially toxic beyond a certain concentration because the survival of the organism is compromised due to scores of pathophysiological abnormalities above that concentration. However, the mechanism of AgNP toxicity remains undetermined. Instead of applying a toxic dose, these investigations were attempted to monitor the effects of AgNPs at a non-lethal concentration on wild type Drosophila melanogaster by exposing them to nanoparticles throughout their development. All adult flies raised in AgNP doped food indicated that of not more than 50 mg/L had no negative influence on median survival; however, these flies appeared uniformly lighter in body color due to the loss of melanin pigments in their cuticle. Additionally, fertility and vertical movement ability were compromised after AgNP feeding. The determination of the amount of free ionic silver (Ag+) indicated that the observed biological effects had resulted from the AgNPs and not from Ag+. Biochemical analysis suggests that the activity of copper dependent enzymes, namely tyrosinase and Cu-Zn superoxide dismutase, were decreased significantly following the consumption of AgNPs, despite the constant level of copper present in the tissue. Furthermore, copper supplementation restored the loss of AgNP induced demelanization, and the reduction of functional Ctr1 in Ctr1 heterozygous mutants caused the flies to be resistant to demelanization. Consequently, these studies proposed a mechanism whereby consumption of excess AgNPs in association with membrane bound copper transporter proteins cause sequestration of copper, thus creating a condition that resembles copper starvation. This model also explained the cuticular demelanization effect resulting from AgNP since tyrosinase activity is essential for melanin biosynthesis. Finally, these investigations demonstrated that Drosophila, an established genetic model system, can be well utilized for further

  9. Degradation and plant uptake of nonylphenol (NP) and nonylphenol-12-ethoxylate (NP12EO) in four contrasting agricultural soils

    International Nuclear Information System (INIS)

    Sjoestroem, A.E.; Collins, C.D.; Smith, S.R.; Shaw, G.

    2008-01-01

    Nonylphenol polyethoxylates (NPEOs) are surfactants found ubiquitously in the environment due to widespread industrial and domestic use. Biodegradation of NPEOs produces nonylphenol (NP), an endocrine disruptor. Sewage sludge application introduces NPEOs and NP into soils, potentially leading to accumulation in soils and crops. We examined degradation of NP and nonylphenol-12-ethoxylate (NP12EO) in four soils. NP12EO degraded rapidly (initial half time 0.3-5 days). Concentrations became undetectable within 70-90 days, with a small increase in NP concentrations after 30 days. NP initially degraded quickly (mean half time 11.5 days), but in three soils a recalcitrant fraction of 26-35% remained: the non-degrading fraction may consist of branched isomers, resistant to biodegradation. Uptake of NP by bean plants was also examined. Mean bioconcentration factors for shoots and seeds were 0.71 and 0.58, respectively. Removal of NP from the soil by plant uptake was negligible (0.01-0.02% of initial NP). Root concentrations were substantially higher than shoot and seed concentrations. - Degradation curves of nonylphenol (NP) and nonylphenol-12-ethoxylate (NP12EO) in four soils indicate that 26-35% of NP is recalcitrant, with minor NP ingrowth from NP12EO breakdown

  10. The role sol-gel process for nuclear fuels - an overview

    International Nuclear Information System (INIS)

    Sood, D.D.

    2009-01-01

    The paper reviews the sol-gel methods used for the preparation of fuel materials in the form of microspheres. It also discusses how these microspheres can be fabricated into nuclear fuels for reactors like High Temperature Gas Cooled Reactors and Fast Reactors. Performance of these microsphere based fuels is reviewed. More recent applications, like transmutation of minor actinides, (Np, Am and Cm) and hydrogen production, are also briefly covered. (author)

  11. Complex chemistry of Np(V) in aqueous solutions

    International Nuclear Information System (INIS)

    Inoue, Yasushi

    1989-01-01

    Despite the importance of Np(V) in both the nuclear chemical engineering and the actinoid chemistry, little work has been performed on the complex chemistry of Np(V) in aqueous solutions, since Np(V) reacts less readily with various ligands. The author has directed his effort to understand the chemical behavior of Np(V) in aqueous solutions, especially the determination of the stability constants of Np(V) complexes with various ligands. A part of the results obtained so far is presented in the following order. (1) The synergistic extraction of Np(V) as a method for studying the complex chemistry of Np(V): TTA-MTOA(methyltrioctylammonium chloride), TTA-phen and TTA-TOPO. (2) The determination of the stability constants of Np(V) complexes with 22 organic- and 5 inorganic ligands by means of the solvent extraction. (3) The distribution of the chemical species of Np(V) in solutions under various conditions

  12. Radiation stability of colloidal metals in aqueous solutions: silver and other metals

    International Nuclear Information System (INIS)

    Ershov, B.G.

    1998-01-01

    The effect of accelerated electrons and γ-rays of 60N i on the stability of aqueous solutions of colloidal silver was studied. The threshold of absorbed dose, at which the stability dramatically decreases and coagulation of the metal occurs, was found. This critical dose corresponds to the reduction of silver ions determining the electrical potential of the sols. Radiation neutralization was also found for cadmium was not observed in the case of thallium, copper and platinum. A mechanism of the effect of radiation, taking into account the electrostatic factor in the stability of metal sols, was considered. (author)

  13. Experimental thermochemistry of neptunium oxides: Np2O5 and NpO2

    Science.gov (United States)

    Zhang, Lei; Dzik, Ewa A.; Sigmon, Ginger E.; Szymanowski, Jennifer E. S.; Navrotsky, Alexandra; Burns, Peter C.

    2018-04-01

    Neptunium (Np) compounds are important in the nuclear fuel cycle because of the buildup and long half-life (2.14 Ma) of Np-237 in nuclear waste, especially during long-term disposal in a geological repository. Neptunium in environmental conditions exists mainly in two oxidation states (+5 and + 4) and can substitute for uranium and/or rare earths in solid phases. Yet thermochemical data for solid neptunium compounds are scarce, despite being critical for evaluating the environmental transport of this radioactive and toxic element. Although high temperature oxide melt solution calorimetry has proven very useful in obtaining thermodynamic data for the formation of uranium and thorium oxide materials, it has not yet been applied to transuranium compounds. Continuing a program at Notre Dame to study the thermodynamics of transuranium compounds, we report the first determination of the enthalpies of drop solution of well-characterized neptunium oxides (Np2O5 and NpO2) using oxide melt solution calorimetry in molten sodium molybdate solvent at 973 K. The enthalpy of the decomposition reaction, Np2O5(cr) = 2NpO2(cr) + 1/2O2(g) at 298 K, is determined to be 7.70 ± 5.86 kJ/mol, and this direct measurement is consistent with existing thermodynamic data. The calorimetric methodology is straightforward and produces reliable data using milligram quantities of radioactive materials, and can be applied to many other transuranium compounds.

  14. The reduction of Np(VI) and Np(V) by tit dihydroxyurea and its application to the U/Np separation in the PUREX process

    Energy Technology Data Exchange (ETDEWEB)

    Yan, T.H.; Zheng, W.F.; Zuo, C.; Xian, L.; Zhang, Y.; Bian, X.Y.; Li, R.X.; Di, Y. [Dept. of Radiochemistry, China Inst. of Atomic Energy, BJ (China)

    2010-07-01

    The reduction of Np(VI) and Np(V) by Dihydroxyurea (DHU) was studied by spectrophotometry. The results show that the reduction of Np(VI) to Np(V) by DHU is particularly fast. The apparent rate constant is 1.86s{sup -1} at 4 C as [HNO{sub 3}] = 0.44 M and [DHU] = 7.5 x 10{sup -2} M. While further reduction of Np(V) to Np(IV) is so slow that no Np(IV) is observed in 2 h. The reduction back-extraction behavior of Np(VI) in 30% tri-butyl phosphate/kerosene was firstly investigated under conditions of different temperature, different concentrations of DHU and HNO{sub 3} and various phase contact time, respectively. The results show that 98% of Np(VI) in the organic phase can be stripped rapidly to the aqueous phase by DHU under the given experimental conditions. As the concentration of HNO{sub 3} in the aqueous phase increases, the stripping efficiency decreases. While the stripping efficiency increases with the increase of the concentration of DHU. Simulating the 1B contactor of the PUREX process using DHU as the stripping agent, the SF{sub U}/Np equals to 183 under the given experimental conditions. It indicates that Np will follow with Pu in the U/Pu separation stage in the reprocessing of spent fuels. (orig.)

  15. The binding of Np to rat bone

    International Nuclear Information System (INIS)

    Ramounet, B.; Taylor, D.M.

    1997-01-01

    Neptunium has been shown to massively deposit in bone, after intravenous or intramuscular injections. Initially, it was uniformly distributed on periosteal and endosteal bone surfaces. The nature of the binding molecules, for this actinide, in the skeleton, has not yet been identified. The aim of this work was to characterize the ligands of neptunium by selective extractions of bone components. The preliminary results displayed the binding of 237 Np(IV) in the organic phase of bone, after intravenous or intramuscular contamination. Further studies are in progress, to quantify the fraction of Np bound to the organic and mineral compartment of bone, and to determine the affinity constant and the turn-over of the binding proteins. (authors)

  16. Solitaire Chess is NP-complete

    OpenAIRE

    Maßberg, Jens

    2015-01-01

    "Solitaire Chess" is a logic puzzle published by Thinkfun, that can be seen as a single person version of traditional chess. Given a chess board with some chess pieces of the same color placed on it, the task is to capture all pieces but one using only moves that are allowed in chess. Moreover, in each move one piece has to be captured. We prove that deciding if a given instance of Solitaire Chess is solvable is NP-complete.

  17. Enhanced efficiency of a fluorescing nanoparticle with a silver shell

    Energy Technology Data Exchange (ETDEWEB)

    Choy, Wallace C H; Chen Xuewen [Department of Electrical and Electronic Engineering, University of Hong Kong, Pokfulam Road (Hong Kong); He Sailing [Centre for Optical and Electromagnetic Research, Zhejiang University, Zhijingang campus, Hangzhou 310058 (China)], E-mail: chchoy@eee.hku.hk

    2009-09-01

    Spontaneous emission (SE) rate and the fluorescence efficiency of a bare fluorescing nanoparticle (NP) and the NP with a silver nanoshell are analyzed rigorously by using a classical electromagnetic approach with the consideration of the nonlocal effect of the silver nano-shell. The dependences of the SE rate and the fluorescence efficiency on the core-shell structure are carefully studied and the physical interpretations of the results are addressed. The results show that the SE rate of a bare NP is much slower than that in the infinite medium by almost an order of magnitude and consequently the fluorescence efficiency is usually low. However, by encapsulating the NP with a silver shell, highly efficient fluorescence can be achieved as a result of a large Purcell enhancement and high out-coupling efficiency (OQE) for a well-designed core-shell structure. We also show that a higher SE rate may not offer a larger fluorescence efficiency since the fluorescence efficiency not only depends on the internal quantum yield but also the OQE.

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

    Science.gov (United States)

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

    2016-04-05

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

  19. Preconcentration of silver as silver xanthate on activated carbon

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  20. Direct patterning of silver particles on porous silicon by inkjet printing of a silver salt via in-situ reduction.

    Science.gov (United States)

    Chiolerio, Alessandro; Virga, Alessandro; Pandolfi, Paolo; Martino, Paola; Rivolo, Paola; Geobaldo, Francesco; Giorgis, Fabrizio

    2012-09-06

    We have developed a method for obtaining a direct pattern of silver nanoparticles (NPs) on porous silicon (p-Si) by means of inkjet printing (IjP) of a silver salt. Silver NPs were obtained by p-Si mediated in-situ reduction of Ag+ cations using solutions based on AgNO3 which were directly printed on p-Si according to specific geometries and process parameters. The main difference with respect to existing literature is that normally, inkjet printing is applied to silver (metal) NP suspensions, while in our experiment the NPs are formed after jetting the solution on the reactive substrate. We performed both optical and scanning electron microscopes on the NPs traces, correlating the morphology features with the IjP parameters, giving an insight on the synthesis kinetics. The patterned NPs show good performances as SERS substrates.

  1. Magnetic properties of Np2T2Sn compounds

    International Nuclear Information System (INIS)

    Sanchez, J.P.; Colineau, E.; Jeandey, C.; Oddou, J.L.; Rebizant, J.; Seret, A.; Spirlet, J.C.

    1994-01-01

    The magnetic properties of the Np 2 T 2 Sn series investigated by 237 Np Moessbauer spectroscopy are reported. Magnetic ordering is shown to occur for T = Ni, Pd, Pt, whereas the Np ions do not carry a local moment when T = Co, Ru, Rh. Comparison is made with the corresponding Np 2 T 2 In and U 2 T 2 Sn compounds. (authors). 5 refs., 3 figs

  2. Precipitation of Np(VI) by urotropine from heated solutions

    International Nuclear Information System (INIS)

    Logvis, A.I.; Krot, N.N.

    1993-01-01

    The precipitate formed by heating HNO 3 solutions of Np(VI) and urotropine under various conditions is studied by x-ray phase analysis, gravimetry, and spectrophotometry. The precipitate is determined to be NpO 3 ·xH 2 O·yNH 3 , where x ≤ 2 and y ≤ 0.28. It is demonstrated that at least 12% of the starting Np remains in solution as Np(V)

  3. Domain Modeling: NP_001034750.1 [SAHG[Archive

    Lifescience Database Archive (English)

    Full Text Available NP_001034750.1 chr11 Solution NMR structure of human myeloid differentiation primary response (MyD88). North...east Structural Genomics target HR2869A p2js7a_ chr11/NP_001034750.1/NP_001034750.1_apo_70-218.pdb psi-blast 0 ...

  4. Domain Modeling: NP_064572.2 [SAHG[Archive

    Lifescience Database Archive (English)

    Full Text Available theast Structural Genomics Consortium Target BoR24. c2bdva_ chr3/NP_064572.2/NP_064572.2_apo_2-265.pdb psi-blast 0 ... ...NP_064572.2 chr3 X-Ray Crystal Structure of Phage-related Protein BB2244 from Bordetella bronchiseptica. Nor

  5. Domain Modeling: NP_001103132.1 [SAHG[Archive

    Lifescience Database Archive (English)

    Full Text Available NP_001103132.1 chr12 CRYSTAL STRUCTURE OF THE SECA PROTEIN TRANSLOCATION ATPASE FROM MYCOBACTERIUM TUBERCULO...SIS COMPLEX WITH ADPBS d1nkta_ chr12/NP_001103132.1/NP_001103132.1_holo_1997-2946.p

  6. Criticality of a 237Np sphere

    International Nuclear Information System (INIS)

    Sanchez, Rene; Loaiza, David; Kimpland, Robert; Hayes, David; Cappiello, Charlene; Chadwick, Mark

    2006-01-01

    For the past five years, scientists at Los Alamos National Laboratory have mounted an unprecedented effort to get a better estimate of the critical mass of 237 Np. To accomplish this task, a 6-kg neptunium sphere was recently cast at the Chemical and Metallurgy Research (CMR) facility, which is part of the Los Alamos National Laboratory. The neptunium sphere was clad with tungsten and nickel to reduce the dose rates from the 310 keV gamma rays from the first daughter of neptunium, namely, 233 Pa. 237 Np is a byproduct of power production in nuclear reactors. It is primarily produced by successive neutron captures in 235 U or through the (n,2n) reaction in 238 U. These nuclear reactions lead to the production of 237 U, which decays by beta emission into 237 Np, namely, 235 U(n,γ) 236 U, 236 U(n,γ) 237 U→β→ 237 Np, 238 U (n,2n) 237 U→β→ 237 Np. It is estimated that a typical 1000 MW(e) produces on the order of 12 to 13 kg of neptunium in a year. Some of this neptunium in irradiated fuel elements has been separated and is presently stored in containers in a liquid form. This method of storage is quite adequate because the fission cross section for 237 Np at thermal energies is quite low and any moderation of the neutron population by diluting the configurations with water would increase the critical mass to infinity. However, for long term storage, the neptunium liquid solutions must be converted into oxides and metals because these form are less movable and less likely to leak out of containers. Metals and oxides made out of neptunium have finite critical masses but there is a great uncertainty about these values because of the lack of experimental criticality data. Knowing precisely the critical mass of neptunium not only will help to validate mass storage limits or optimize storage configurations for safe disposition of these materials, but will also save thousands of dollars in transportation and disposition costs. The experimental results presented in

  7. The release of silver nanoparticles from commercial toothbrushes

    DEFF Research Database (Denmark)

    Mackevica, Aiga; Olsson, Mikael Emil; Hansen, Steffen Foss

    2017-01-01

    The use of silver nanoparticles (NPs) in commercial products has become increasingly common in the past decade, mostly due to their antimicrobial properties. Using Ag NP-containing articles may lead to particle release, which raises concern of human and environmental safety. The published...... literature addressing particle release is scarce, especially when it comes to quantifying exposure to NPs specifically. In this study, we have experimentally investigated the release of total Ag and Ag NP from commercially available toothbrushes i.e. biodegradable toothbrushes for adults and toothbrushes...

  8. 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.

  9. Opportunity's Surroundings on Sol 1687

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008). Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction. Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast. This view is presented as a cylindrical projection with geometric seam correction.

  10. Sol-gel derived sorbents

    Science.gov (United States)

    Sigman, Michael E.; Dindal, Amy B.

    2003-11-11

    Described is a method for producing copolymerized sol-gel derived sorbent particles for the production of copolymerized sol-gel derived sorbent material. The method for producing copolymerized sol-gel derived sorbent particles comprises adding a basic solution to an aqueous metal alkoxide mixture for a pH.ltoreq.8 to hydrolyze the metal alkoxides. Then, allowing the mixture to react at room temperature for a precalculated period of time for the mixture to undergo an increased in viscosity to obtain a desired pore size and surface area. The copolymerized mixture is then added to an immiscible, nonpolar solvent that has been heated to a sufficient temperature wherein the copolymerized mixture forms a solid upon the addition. The solid is recovered from the mixture, and is ready for use in an active sampling trap or activated for use in a passive sampling trap.

  11. Silver Nanoparticles in Alveolar Bone Surgery Devices

    Directory of Open Access Journals (Sweden)

    Stefano Sivolella

    2012-01-01

    Full Text Available Silver (Ag ions have well-known antimicrobial properties and have been applied as nanostrategies in many medical and surgical fields, including dentistry. The use of silver nanoparticles (Ag NPs may be an option for reducing bacterial adhesion to dental implant surfaces and preventing biofilm formation, containing the risk of peri-implant infections. Modifying the structure or surface of bone grafts and membranes with Ag NPs may also prevent the risk of contamination and infection that are common when alveolar bone augmentation techniques are used. On the other hand, Ag NPs have revealed some toxic effects on cells in vitro and in vivo in animal studies. In this setting, the aim of the present paper is to summarize the principle behind Ag NP-based devices and their clinical applications in alveolar bone and dental implant surgery.

  12. Opportunity's Surroundings on Sol 1818

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends. The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view. The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock. This view is presented as a cylindrical projection with geometric seam correction.

  13. Behavior and chronic toxicity of two differently stabilized silver nanoparticles to Daphnia magna

    DEFF Research Database (Denmark)

    Sakka, Yvonne; Skjolding, Lars Michael; Mackevica, Aiga

    2016-01-01

    While differences in silver nanoparticle (AgNP) colloidal stability, surface potential, or acute aquatic toxicity for differently stabilized AgNP have often been reported, these have rarely been studied in long-term ecotoxicity tests. In the current study, we investigated the chronic toxicity of Ag...... types of AgNP during a typical media exchange period in the D. magna test for chronic toxicity. As expected, the sterically stabilized AgNP were more stable in the test medium, also in the presence of food; however, a higher uptake of silver after 24 h exposure of the charge stabilized AgNP was found...... compared to the detergent-stabilized AgNP (0.046 ± 0.006 μg Ag μg DW−1 and 0.023 ± 0.005 μg Ag μg DW−1, respectively). In accordance with this, the higher reproductive effects and mortality were found for the charge-stabilized than for the sterically-stabilized silver nanoparticles in 21-d tests...

  14. Puesto remisión de V. sol puesto a sol puesto, de.

    OpenAIRE

    2011-01-01

    [ES] Definición del término Puesto remisión de V. sol puesto a sol puesto, de. en el diccionario Dicter. [EN] Definition of the word Puesto remisión de V. sol puesto a sol puesto, de. in the dictionary Dicter.

  15. 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.

  16. Comparison of DNA Damage and Apoptosis Induced By Silver Nanoparticle-containing Dressing Materials During Wound Healing.

    Science.gov (United States)

    Choi, Young Suk; Gwak, Heui-Chul; Park, Jae Keun; Lim, Ji Yun; Yeo, Eui Dong; Park, Eunseok; Kim, Junyong; Lee, Young Koo

    2018-04-13

    Silver nanoparticle (AgNP)-containing dressings are used worldwide for the treatment of wounds; however, many studies have indicated that AgNPs are toxic to humans and cause cell death, primarily via apoptosis. In this study, the investigators compare the apoptotic effects of various AgNP dressing materials, with the hypothesis that nanosilver would be less toxic than ionic silver. For the in vivo experiments, Sprague-Dawley (SD) and streptozotocin (STZ)-induced diabetic rats were treated with 5 dressing materials: Aquacel Ag (product A, silver ion; ConvaTec, Berkshire, UK), Acticoat (product B, AgNP; Smith & Nephew, Fort Worth, TX), Medifoam Silver (product C, silver ion; Genewel Science Co Ltd, Seongnam, South Korea), PolyMem Silver (product D, AgNP; Ferris Mfg Corp, Fort Worth, TX), and Vaseline-impregnated dressing gauze (control; Unilever, London, UK). All treatments were applied 3 times per week. After 14 days of treatment, the SD and STZ rats were euthanized, and wound samples were examined for apoptosis. The analysis included immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, Western blotting, and reverse transcription polymerase chain reaction for a semiquantitative evaluation of apoptosis. The AgNP-containing dressing materials were more cytotoxic than the silver dressings. Compared with the AgNP dressing materials, no significant levels of apoptotic factors were observed in the silver dressing-treated wounds. The TUNEL staining showed that product C-dressed wounds contained the most apoptotic cells, while some apoptotic cells were observed in product B-dressed wounds. Moreover, apoptotic gene expression was altered, including a decline in B-cell lymphoma-2 and activation of caspase-3. This was most evident in wounds treated with product C. Interestingly, apoptotic gene expression was not induced in product A-treated wounds. Finally, product D had a relatively lower silver concentration and was less toxic

  17. Update neutron nuclear data evaluation for 236,238Np

    International Nuclear Information System (INIS)

    Chen, Guochang; Wang, Jimin; Yu, Baosheng; Cao, Wentian; Tang, Guo-you

    2015-01-01

    The nuclear data with high accuracy for actinides play an important role in nuclear technology applications, including reactor design and operation, fuel cycle, estimation of the amount of minor actinides (MAs) in high burnup reactors and to research to transmute the MAs to short half-lived nuclides or stable ones. The nuclides of 236 Np are generated via the α-decay of 240 Am or 237 Np(n, 2n) and 237 Np(d, t) reactions. And the nuclides of 238 Np are generated via the α-decay of 242 Am or 237 Np(n, γ) and 237 Np(d, p) reactions. In the present work, according to the systematic trend of the total cross section and elastic cross section etc. of different Np isotopes, and based on the neutron optical model parameters (OMP) of 237 Np, a new set of neutron optical model parameters were obtained for 236,238 Np. Based on the new set OMP and the systematic trend of the cross sections of different Np isotopes, a full set of 236,238 Np neutron nuclear data has been updated and improved by theoretical calculation. The present result has significant improvements over the data in CENDL-3.1

  18. Dispersion of silver particles in aqueous solutions visualized by polarography/voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Korshunov, Andrey [Department of General and Inorganic Chemistry, Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Heyrovsky, Michael [J.Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, 182 23 Prague (Czech Republic)], E-mail: heyrovsk@jh-inst.cas.cz

    2009-11-01

    The State of silver particles in aqueous dispersions and the course of their coagulation can be followed on voltammetric curves recorded with hanging mercury drop electrode. Sharp irregular cathodic current peaks produced by partial electroreduction of the species adsorbed on the surface of silver particles during their fortuitous impingements upon the electrode surface appear in time sequence on the curves. A change in the electrochemical behavior of silver sols in the time course of particles aggregation and growth was interpreted in agreement with the data of UV-vis spectroscopy and electron microscopy observations.

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, Laura E.; Giacomelli, Carla E., E-mail: giacomel@fcq.unc.edu.ar [Universidad Nacional de Córdoba, Ciudad Universitaria, Instituto de Investigaciones en Físico Química de Córdoba (INFIQC) CONICET-UNC, Departamento de Fisicoquímica, Facultad de Ciencias Químicas (Argentina)

    2017-05-15

    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{sup +} 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 (H{sub 2}O{sub 2}). 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. H{sub 2}O{sub 2}-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{sup +} from Ag-NP, related to the cell toxicity and relevant to the storage and lifetime of silver-containing nanomaterials.

  1. Sol-Gel Derived Hafnia Coatings

    Science.gov (United States)

    Feldman, Jay D.; Stackpoole, Mairead; Blum, Yigal; Sacks, Michael; Ellerby, Don; Johnson, Sylvia M.; Venkatapathy, Ethiras (Technical Monitor)

    2002-01-01

    Sol-gel derived hafnia coatings are being developed to provide an oxidation protection layer on ultra-high temperature ceramics for potential use in turbine engines (ultra-efficient engine technology being developed by NASA). Coatings using hafnia sol hafnia filler particles will be discussed along with sol synthesis and characterization.

  2. Modeling SOL evolution during disruptions

    International Nuclear Information System (INIS)

    Rognlien, T.D.; Cohen, R.H.; Crotinger, J.A.

    1996-01-01

    We present the status of our models and transport simulations of the 2-D evolution of the scrape-off layer (SOL) during tokamak disruptions. This evolution is important for several reasons: It determines how the power from the core plasma is distributed on material surfaces, how impurities from those surfaces or from gas injection migrate back to the core region, and what are the properties of the SOL for carrying halo currents. We simulate this plasma in a time-dependent fashion using the SOL transport code UEDGE. This code models the SOL plasma using fluid equations of plasma density, parallel momentum (along the magnetic field), electron energy, ion energy, and neutral gas density. A multispecies model is used to follow the density of different charge-states of impurities. The parallel transport is classical but with kinetic modifications; these are presently treated by flux limits, but we have initiated more sophisticated models giving the correct long-mean-free path limit. The cross-field transport is anomalous, and one of the results of this work is to determine reasonable values to characterize disruptions. Our primary focus is on the initial thermal quench phase when most of the core energy is lost, but the total current is maintained. The impact of edge currents on the MHD equilibrium will be discussed

  3. Short communication: Unexpected findings on the physicochemical characterization of the silver nanoparticle surface

    Science.gov (United States)

    Loran, S.; Yelon, A.; Sacher, E.

    2018-01-01

    The bactericidal properties of silver nanoparticles (Ag NPs) have been variously attributed to the action of the NP surface and/or the Ag ions released therefrom. However, the published literature does not appear to contain any information on the physicochemical characterization of the NP surface. Herein, we report on the surprisingly reactive surface of the Ag NP, which has an almost total lack of free Ag on atmospheric exposure. Rather, an abundance of surface hydrocarbons, hydrides and oxides, as well as amines and oxidized N, argues for a reinterpretation of their bactericidal action.

  4. Influence of daylight on the fate of silver and zinc oxide nanoparticles in natural aquatic environments

    International Nuclear Information System (INIS)

    Odzak, Niksa; Kistler, David; Sigg, Laura

    2017-01-01

    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. - Highlights: • Effects of visible and UV-light on dissolution of silver and zinc oxide nanoparticles were examined. • Natural waters

  5. Nuclear Physics Research at ELI-NP

    Science.gov (United States)

    Zamfir, N. V.

    2018-05-01

    The new research facility Extreme Light Infrastructure - Nuclear Physics (ELI-NP) is under construction in Romania, on the Magurele Physics campus. Valued more than 300 Meuros the center will be operational in 2019. The research center will use a high brilliance Gamma Beam and a High-power Laser beam, with unprecedented characteristics worldwide, to investigate the interaction of very intense radiation with matter with specific focus on nuclear phenomena and their applications. The energetic particle beams and radiation produced by the 2x10 PW laser beam interacting with matter will be studied. The precisely tunable energy and excellent bandwidth of the gamma-ray beam will allow for new experimental approaches regarding nuclear astrophysics, nuclear resonance fluorescence, and applications. The experimental equipment is presented, together with the main directions of the research envisioned with special emphasizes on nuclear physics studies.

  6. Enzymatic functionalization of cork surface with antimicrobial hybrid biopolymer/silver nanoparticles.

    Science.gov (United States)

    Francesko, Antonio; Blandón, Lucas; Vázquez, Mario; Petkova, Petya; Morató, Jordi; Pfeifer, Annett; Heinze, Thomas; Mendoza, Ernest; Tzanov, Tzanko

    2015-05-13

    Laccase-assisted assembling of hybrid biopolymer-silver nanoparticles and cork matrices into an antimicrobial material with potential for water remediation is herein described. Amino-functional biopolymers were first used as doping agents to stabilize concentrated colloidal dispersions of silver nanoparticles (AgNP), additionally providing the particles with functionalities for covalent immobilization onto cork to impart a durable antibacterial effect. The solvent-free AgNP synthesis by chemical reduction was carried out in the presence of chitosan (CS) or 6-deoxy-6-(ω-aminoethyl) aminocellulose (AC), leading to simultaneous AgNP biofunctionalization. This approach resulted in concentrated hybrid NP dispersion stable to aggregation and with hydrodynamic radius of particles of about 250 nm. Moreover, laccase enabled coupling between the phenolic groups in cork and amino moieties in the biopolymer-doped AgNP for permanent modification of the material. The antibacterial efficiency of the functionalized cork matrices, aimed as adsorbents for wastewater treatment, was evaluated against Escherichia coli and Staphylococcus aureus during 5 days in conditions mimicking those in constructed wetlands. Both intrinsically antimicrobial CS and AC contributed to the bactericidal effect of the enzymatically grafted on cork AgNP. In contrast, unmodified AgNP were easily washed off from the material, confirming that the biopolymers potentiated a durable antibacterial functionalization of the cork matrices.

  7. Adsorption of silver nanoparticles from aqueous solution on copper-based metal organic frameworks (HKUST-1).

    Science.gov (United States)

    Conde-González, J E; Peña-Méndez, E M; Rybáková, S; Pasán, J; Ruiz-Pérez, C; Havel, J

    2016-05-01

    Silver nanoparticles (AgNP) are emerging pollutants. The use of novel materials such as Cu-(benzene 1,3,5-tricarboxylate, BTC) Metal-Organic Framework (MOFs), for AgNP adsorption and their removal from aqueous solutions has been studied. The effect of different parameters was followed and isotherm model was suggested. MOFs adsorbed fast and efficiently AgNP in the range C0 < 10 mg L(-1), being Freundlich isotherm (R = 0.993) these data fitted to. Among studied parameters a remarkable effect of chloride on sorption was found, thus their possible interactions were considered. The high adsorption efficiency of AgNP was achieved and it was found to be very fast. The feasibility of adsorption on Cu-(BTC) was proved in spiked waters. The results showed the potential interest of new material as adsorbent for removing AgNP from environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Effect of Accelerator in Green Synthesis of Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kamyar Shameli

    2010-10-01

    Full Text Available Silver nanoparticles (Ag-NPs were successfully synthesized in the natural polymeric matrix. Silver nitrate, gelatin, glucose, and sodium hydroxide have been used as silver precursor, stabilizer, reducing agent, and accelerator reagent, respectively. This study investigated the role of NaOH as the accelerator. The resultant products have been confirmed to be Ag-NPs using powder X-ray diffraction (PXRD, UV-vis spectroscopy, and transmission electron microscopy (TEM. The colloidal sols of Ag-NPs obtained at different volumes of NaOH show strong and different surface plasmon resonance (SPR peaks, which can be explained from the TEM images of Ag-NPs and their particle size distribution. Compared with other synthetic methods, this work is green, rapid, and simple to use. The newly prepared Ag-NPs may have many potential applications in chemical and biological industries.

  9. Adsorption of iodide and iodate on colloidal silver surface

    International Nuclear Information System (INIS)

    Zhang Aiping; Tie Xiaoyun; Zhang Jinzhi; An Yanwei; Li Lingjie

    2008-01-01

    'Chemically pure' silver colloids were prepared by laser ablated method to investigate their adsorption-induced spectral and morphologic changes, using UV-visible absorption, Raman and transmission electron microscopy (TEM) techniques, when nucleophilic different anions (IO 3 - and I - ) were added into sols. It reveals that the adsorption of nucleophiles on silver surfaces leads to an excess negative charge in the metal interior and modifies both surface charge density and the Fermi levels of metal, which is responsible for the colloidal aggregation, reconstruction and appearance of new resonance absorption bands or with wavelength shift. In addition, two models regarding different adsorption effects of these two anions on silver surfaces were proposed to explain their variant spectral and TEM phenomena.

  10. Photocatalytic decomposition of diclofenac potassium using silver-modified TiO2 thin films

    International Nuclear Information System (INIS)

    Cavalheiro, A.A.; Bruno, J.C.; Saeki, M.J.; Valente, J.P.S.; Florentino, A.O.

    2008-01-01

    The effects of silver insertion on the TiO 2 photocatalytic activity for the degradation of diclofenac potassium were reported here. Techniques such as X-ray diffraction, scanning electron microscopy and UV-Vis spectroscopy were used to comprehend the relation between structure and properties of the silver-modified TiO 2 thin films obtained by the sol-gel method. The lattice parameters and the crystallinity of TiO 2 anatase phase were affected by inserted silver, and the film thickness increased about 4 nm for each 1 wt.% of silver inserted. The degradation of diclofenac potassium and by-products reached an efficiency of 4.6 mg C W -1 when the material was modified with silver. Although the first step of degradation involves only the photochemical process related to the loss of the chlorine and hydrogen atoms. This cyclization reaction leads to the formation of intermediate, which degradation is facilitated by the modified material

  11. Ionizing radiation effect on central venous catheters (CVC) of polyurethane coatings with silver nanoparticles

    International Nuclear Information System (INIS)

    Heilman, Sonia; Silva, Leonardo G.A.; Hewer, Thiago L.R.; Souza, Michele L.

    2015-01-01

    The present work aimed to study the use of ionizing radiation for coating of silver nanoparticles on central polyurethane catheters, providing reduction of infections associated with contamination of catheters introduced into the bloodstream. Silver nanoparticles have physical, chemical and biological properties only when compared to metal on a macroscopic scale, and have been used in the medical field because of its remarkable antimicrobial activity. Titanium dioxide nanoparticles obtained by the sol gel method were used as the coating catheters for subsequent impregnation of silver nanoparticles with ionizing radiation at doses of 25 and 50 kGy. A Raman spectrometry was used to identify the polymorph of titanium oxide, rutile. In trials with (ICP OES) were evaluated amounts of titanium and silver coated catheters in titanium oxide and silver.(author)

  12. UV-induced photochemical transformations of citrate-capped silver nanoparticle suspensions

    International Nuclear Information System (INIS)

    Gorham, Justin M.; MacCuspie, Robert I.; Klein, Kate L.; Fairbrother, D. Howard; Holbrook, R. David

    2012-01-01

    Due to the increasing use of silver nanoparticles (AgNPs) in consumer products, it is essential to understand how variables, such as light exposure, may change the physical and chemical characteristics of AgNP suspensions. To this end, the effect of 300 nm ultraviolet (UV) light on (20, 40, 60 and 80) nm citrate-capped AgNP suspensions has been investigated. As a consequence of irradiation, the initial yellow hue of the AgNP suspensions is transformed towards a near colorless solution due to the loss of the surface plasmon resonance (SPR) absorbance. The decrease in SPR absorbance followed a first-order decay process for all particle sizes with a rate constant that increased linearly with the AgNP specific surface area and non-linearly with light intensity. The rate of loss of the SPR absorbance decreased with increasing citrate concentration, suggesting a surface-mediated transformation. Absorbance, atomic force microscopy, and dynamic light scattering results all indicated that AgNP photolysis was accompanied by a diameter decrease and occasional aggregation. Furthermore, in situ transmission electron microscopy imaging using a specialized liquid cell also showed a decrease in the particle size and the formation of a core–shell structure in UV-exposed AgNPs. X-ray photoelectron spectroscopy analysis suggested that this shell consisted of oxidized silver. The SPR in UV-exposed AgNP suspensions could be regenerated by addition of a strong reducing agent (NaBH 4 ), supporting the idea that oxidized silver is present after photolysis. Evidence for UV-enhanced dissolution and the production of silver ions was obtained with the Donnan membrane technique. This study reveals that the physico-chemical properties of aqueous AgNP suspensions will change significantly upon exposure to UV light, with implications for environmental health and safety risk assessments.

  13. Investigating Oxidative Stress and Inflammatory Responses Elicited by Silver Nanoparticles Using High-Throughput Reporter Genes in HepG2 Cells: Effect of Size, Surface Coating, and Intracellular Uptake

    Science.gov (United States)

    Abstract Silver nanoparticles (Ag NP) have been shown to generate reactive oxygen species; however, the association between physicochemical characteristics of nanoparticles and cellular stress responses elicited by exposure has not been elucidated. Here, we examined three key...

  14. Silver Nanoparticles in the Lung: Toxic Effects and Focal Accumulation of Silver in Remote Organs

    Directory of Open Access Journals (Sweden)

    Martin Wiemann

    2017-12-01

    Full Text Available The distribution of silver (Ag into remote organs secondary to the application of Ag nanoparticles (Ag-NP to the lung is still incompletely understood and was investigated in the rat with imaging methods. Dose-finding experiments were carried out with 50 nm- or 200 nm-sized polyvinyl pyrrolidine (PVP-coated Ag-NP using alveolar macrophages in vitro and female rats, which received Ag-NP via intratracheal instillation. In the main study, we administered 37.5–300 µg per rat lung of the more toxic Ag50-PVP and assessed the broncho-alveolar lavage fluid (BALF for inflammatory cells, total protein and fibronectin after three and 21 days. In parallel, lung tissue was analysed for DNA double-strand breaks and altered cell proliferation. While 75–150 µg Ag50-PVP per rat lung caused a reversible inflammation, 300 µg led to DNA damage, accelerated cell proliferation and progressively increasing numbers of neutrophilic granulocytes. Ag accumulation was significant in homogenates of liver and other peripheral organs upon lung dose of ≥75 µg. Quantitative laser-ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS combined with enhanced dark field microscopy and autometallography revealed focal accumulations of Ag and/or Ag-NP in sections of peripheral organs: mediastinal lymph nodes contained Ag-NP especially in peripheral macrophages and Ag in argyrophilic fibres. In the kidney, Ag had accumulated within proximal tubuli, while renal filter structures contained no Ag. Discrete localizations were also observed in immune cells of liver and spleen. Overall, the study shows that concentrations of Ag-NP, which elicit a transient inflammation in the rat lung, lead to focal accumulations of Ag in peripheral organs, and this might pose a risk to particular cell populations in remote sites.

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

    International Nuclear Information System (INIS)

    Shirzaditabar, Farzad; Saliminasab, Maryam

    2013-01-01

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

  16. Colloidal stability of carbonate-coated silver nanoparticles in synthetic and natural freshwater.

    Science.gov (United States)

    Piccapietra, Flavio; Sigg, Laura; Behra, Renata

    2012-01-17

    To gain important information on fate, mobility, and bioavailability of silver nanoparticles (AgNP) in aquatic systems, the influence of pH, ionic strength, and humic substances on the stability of carbonate-coated AgNP (average diameter 29 nm) was systematically investigated in 10 mM carbonate and 10 mM MOPS buffer, and in filtered natural freshwater. Changes in the physicochemical properties of AgNP were measured using nanoparticle tracking analysis, dynamic light scattering, and ultraviolet-visible spectroscopy. According to the pH-dependent carbonate speciation, below pH 4 the negatively charged surface of AgNP became positive and increased agglomeration was observed. Electrolyte concentrations above 2 mM Ca(2+) and 100 mM Na(+) enhanced AgNP agglomeration in the synthetic media. In the considered concentration range of humic substances, no relevant changes in the AgNP agglomeration state were measured. Agglomeration of AgNP exposed in filtered natural freshwater was observed to be primarily controlled by the electrolyte type and concentration. Moreover, agglomerated AgNP were still detected after 7 days of exposure. Consequently, slow sedimentation and high mobility of agglomerated AgNP could be expected under the considered natural conditions. A critical evaluation of the different methods used is presented as well.

  17. Sorption of Np (Ⅴ) on Beishan granite fracture filling materials

    International Nuclear Information System (INIS)

    Jiang Tao; Wang Bo; Bao Liangjin; Zhou Duo; Long Haoqi; Song Zhixin; Chen Xi

    2012-01-01

    The sorption behaviors of Np (Ⅴ) on the granite fracture filling materials were studied by batch experiments under anaerobic in Beishan groundwater. The impact of pH of groundwater, CO 3 2- , humic acid and different components of granite fracture filling materials on sorption of Np (Ⅴ) was investigated. The results show that the granite fracture filling materials have strong capacity of Np (Ⅴ) adsorption. The value of K d , for Np (Ⅴ) sorption on the granite fracture filling materials is 843 mL/g. With the increase of pH, the value of K d increases at first and then decreases. K d of Np sorption on granite fracture filling materials in the presence of CO 3 2- and humic acid decreases. The chlorite and feldspar are major contributors to the sorption of Np (Ⅴ) on Beishan granite fracture filling materials. (authors)

  18. Solubility studies of Np(V) in simulated underground water

    International Nuclear Information System (INIS)

    Zhang Yingjie; Ren Lilong; Jiao Haiyang; Yao Jun; Su Xiguang; Fan Xianhua

    2004-01-01

    The solubility of Np(V) in simulated underground water has been measured with the variation of pH, storage time (0-100 days). All experiments were performed in an Ar glove box which contained high purity Ar, with an oxygen content of less than 5ppm. Experimental results show that the solubility of Np(V) in simulated underground water decreased with increasing pH value of solution; the solubility of Np(V) in simulated underground water determined at different pH is : pH=6.96, [Np(V)]=(3.52±0.37) x 10 -4 mol/L; pH=8.04, [Np(V)]=(8.24±0.32) x 10 -5 mol/L; pH=9.01, [Np(V)]=(3.04±0.48) x 10'- 5 mol/L, respectively. (author)

  19. NpX3 compounds under high pressure

    International Nuclear Information System (INIS)

    Zwirner, S.; Kalvius, G.M.

    1993-01-01

    The systematics of hyperfine interactions and the ordering temperature T ord in isostructural NpX 3 compounds (X=Al, Si, Ga, Ge, ln, Sn) are briefly reviewed. NpSn 3 has been viewed as a Kondo lattice system, similar to CeAl 2 , NpIn 3 shows a modulated magnetic structure including low moment and nonmagnetic contributions at ambient pressure and 4.2 K. Preliminary results of recent 237 Np Moessbauer studies on NpIn 3 at ambient pressure and various temperatures and at 4.0(8) GPa and 4.2 K are reported. At 4.0(8) GPa, T ord rises from 17 to 22 K, the low-moment contributions of the modulated structure are reduced and the non-magnetic site is lost below T ord . The variation of the hyperfine parameters and of T ord with pressure is similar to the behavior observed in NpSn 3 . (orig.)

  20. Ameliorative role of nano-ceria against amine coated Ag-NP induced toxicity in Labeo rohita

    Science.gov (United States)

    Khan, Muhammad Saleem; Qureshi, Naureen Aziz; Jabeen, Farhat

    2018-03-01

    Silver nanoparticles (Ag-NPs) and its byproducts can spread pollution in aquatic habitat. Liver and gills are key target for toxicity. Oxidative stress, tissue alterations, and hemotoxicity are assumed to be associated with Ag-NPs in target animals. Cerium oxide nanoparticles (nano-ceria) show antioxidant potential in scavenging the free radicals generated in Ag-NP-induced oxidative stress. We determined ameliorated role of nano-ceria against Ag-NP-induced toxicity in fresh water Labeo rohita (L. rohita). Four groups were used in study including control, nano-ceria, Ag-NPs, and Ag-NPs + nano-ceria. Ag-NPs (30 mg l-1) and nano-ceria (50 µg kg-1) were given through water and prepared feed, respectively. The samples were taken after 28 days. Results demonstrated that pre-treatment of nano-ceria recovered L. rohita from Ag-NP-induced toxicity and oxidative stress. Nano-ceria pre-treatment actively mimics the activity of GST, GSH, CAT, and SOD. Furthermore, Ag-NPs' treatment caused severe inflammation and necrosis in hepatic parenchyma which leaded to congestion of blood in hepatic tissues. Accumulation of a yellow pigment in hepatic tissue was also seen due to necrosis of affected cells. In nano-ceria pre-treatment, there was no congestion in hepatic tissue. Vacuolization of cells and necrosis in some area was recorded in nano-ceria pre-treated group, but the gill and hepatic tissue showed improvement against Ag-NP-induced damage. Nano-ceria pre-treatment also improved hematological parameters in Ag-NP-treated fish. This study concluded that Ag-NP-induced toxicity in treated fish and pre-treatment of nano-ceria show ameliorative role.

  1. Aqueous-Phase Synthesis of Silver Nanodiscs and Nanorods in Methyl Cellulose Matrix: Photophysical Study and Simulation of UV–Vis Extinction Spectra Using DDA Method

    Directory of Open Access Journals (Sweden)

    Sarkar Priyanka

    2010-01-01

    Full Text Available Abstract We present a very simple and effective way for the synthesis of tunable coloured silver sols having different morphologies. The procedure is based on the seed-mediated growth approach where methyl cellulose (MC has been used as soft-template in the growth solution. Nanostructures of varying morphologies as well as colour of the silver sols are controlled by altering the concentration of citrate in the growth solution. Similar to the polymers in the solution, citrate ions also dynamically adsorbed on the growing silver nanoparticles and promote one (1-D and two-dimensional (2-D growth of nanoparticles. Silver nanostructures are characterized using UV–vis and HR-TEM spectroscopic study. Simulation of the UV–vis extinction spectra of our synthesized silver nanostructures has been carried out using discrete dipole approximation (DDA method.

  2. 239Np application as tracer of 237Np in liquid effluents and nuclear wastes

    International Nuclear Information System (INIS)

    Diodati, Jorge M; Sartori, F.M.

    2003-01-01

    In this paper a technique to separate and measure 237 Np using 239 Np as a tracer, is presented. After the radiochemical separation, a liquid scintillation measurement with pulse decay discrimination and a γ measurement on the same vial is performed. The method also allows an electrodeposition for an α and γ measurement. The chemical recoveries obtained by LSC and γ spectrometry in vial are similar to those obtained by α and γ spectrometry on electroplated disc. The MDA is 0.08 Bq/l by α spectrometry and 0.22 Bq/l by LSC, with 2 σconfidence interval, and 93.7 % measurement efficiency and 98.0% chemical recovery. (author)

  3. Short-term bioconcentration studies of Np in freshwater biota

    International Nuclear Information System (INIS)

    Poston, T.M.; Klopfer, D.C.; Simmons, M.A.

    1990-01-01

    Short-term laboratory exposures were conducted to determine the potential accumulation of Np in aquatic organisms. Concentration factors were highest in green algae. Daphnia magna, a filter-feeding crustacean, accumulated Np at levels one order of magnitude greater than the amphipod Gammarus sp., an omnivorous substrate feeder. Accumulation of Np in juvenile rainbow trout (Oncorhynchus mykiss) was highest in carcass (generally greater than 78% of the total body burden) and lowest in fillets. Recommended concentration factors for Np, based on fresh weight, were 300 for green algae, 100 for filter-feeding invertebrates, for nonfilter-feeding invertebrates, 10 for whole fish, and one for fish flesh

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

    Directory of Open Access Journals (Sweden)

    Jens Boenigk

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

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

    Science.gov (United States)

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

    2017-10-01

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

  6. Opportunity's Surroundings on Sol 1798

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 180-degree view of the rover's surroundings during the 1,798th Martian day, or sol, of Opportunity's surface mission (Feb. 13, 2009). North is on top. The rover had driven 111 meters (364 feet) southward on the preceding sol. Tracks from that drive recede northward in this view. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock. This view is presented as a cylindrical projection with geometric seam correction.

  7. Silver nanoparticles in X-ray biomedical applications

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  8. Metal-silica sol-gel materials

    Science.gov (United States)

    Stiegman, Albert E. (Inventor)

    2002-01-01

    The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

  9. Green fabrication of quaternized chitosan/rectorite/Ag NP nanocomposites with antimicrobial activity

    International Nuclear Information System (INIS)

    Luo, Jiwen; Xie, Meijia; Wang, Xiaoying

    2014-01-01

    Silver nanoparticles (Ag NPs) were synthesized rapidly in one pot via the Tollens reaction, in which quaternized chitosan (QCS) and rectorite (REC) acted as the reducing and stabilizing agent, while other chemical reducing and stabilizing agents and the surfactant were not included. X-ray diffraction, scanning electron microscopy and transmission electron microscopy results showed that spherical Ag NPs with uniform sizes were obtained, the layers of clay were peeled and thus exfoliated QCS/REC/Ag NP (QCRAg) nanocomposite was achieved. Moreover, Ag NPs dispersed well in the exfoliated nanocomposite matrix, some Ag NPs even entered into the interlayer of REC. QCRAg nanocomposites showed strong antimicrobial activity; the lowest minimum inhibitory concentration against Staphyloccocus aureus was only 0.0001% (w/v). The study reveals that the obtained QCRAg nanocomposites have great potential for biomedical applications. (communication)

  10. Effect of surface density silver nanoplate films toward surface-enhanced Raman scattering enhancement for bisphenol A detection

    Science.gov (United States)

    Bakar, N. A.; Salleh, M. M.; Umar, A. A.; Shapter, J. G.

    2018-03-01

    This paper reports a study on surface-enhanced Raman scattering (SERS) phenomenon of triangular silver nanoplate (NP) films towards bisphenol A (BPA) detection. The NP films were prepared using self-assembly technique with four different immersion times; 1 hour, 2 hours, 5 hours, and 8 hours. The SERS measurement was studied by observing the changes in Raman spectra of BPA after BPA absorbed on the NP films. It was found that the Raman intensity of BPA peaks was enhanced by using the prepared SERS substrates. This is clearly indicated that these SERS silver substrates are suitable to sense industrial chemical and potentially used as SERS detector. However, the rate of SERS enhancement is depended on the distribution of NP on the substrate surface.

  11. Effect of silver nanoparticles on the physicochemical and antimicrobial properties of an orthodontic adhesive

    Directory of Open Access Journals (Sweden)

    Felipe Weidenbach DEGRAZIA

    Full Text Available ABSTRACT Orthodontic treatment with fixed brackets plays a major role on the formation of white spot lesions. Objective This study aimed to incorporate silver nanoparticle solutions (AgNP in an orthodontic adhesive and evaluate its physicochemical and antimicrobial properties. Material and Methods Silver nanoparticle solutions were added to a commercial adhesive in different concentrations (w/w: 0%, 0.11%, 0.18%, and 0.33%. Shear bond strength (SBS test was performed after bonding metal brackets to enamel. Raman spectroscopy was used to analyze in situ the degree of conversion (DC of the adhesive layer. The surface free energy (SFE was evaluated after the measurement of contact angles. Growth inhibition of Streptococcus mutans in liquid and solid media was determined by colony-forming unit count and inhibition halo, respectively. One-way ANOVA was performed for SBS, DC, SFE, and growth inhibition. Results The incorporation of AgNP solution decreased the SBS (p<0.001 and DC in situ (p<0.001 values. SFE decreased after addition of 0.18% and 0.33% AgNP. Growth inhibition of S. mutans in liquid media was obtained after silver addition (p<0.05. Conclusions The addition of AgNP solutions to Transbond™ XT adhesive primer inhibited S. mutans growth. SBS, DC, and SFE values decreased after incorporation up to 0.33% AgNP solution without compromising the chemical and physical properties of the adhesive.

  12. Subacute oral toxicity investigation of nanoparticulate and ionic silver in rats

    DEFF Research Database (Denmark)

    Hadrup, Niels; Löschner, Katrin; Bergström, Anders

    2012-01-01

    Subacute toxicity of 14 nm nanoparticulate silver (Ag-NP) stabilised with polyvinylpyrrolidone and ionic silver in the form of silver acetate (Ag-acetate) was investigated in four-week-old Wistar rats. Animals received orally by gavage the following: vehicle control (10 $, 6 #); Ag-NP at doses: 2.......25 (8 $), 4.5 (8 $) or 9 mg/kg bw/day (10 $, 6 #); or Ag-acetate 9 mg silver/kg bw/day (8 $) for 28 days. Clinical, haematolological and biochemical parameters, organ weights, macro- and microscopic pathological changes were investigated. Caecal bacterial phyla and their silver resistance genes were...... quantified. For the Ag-NP groups, no toxicological effects were recorded. For Ag-acetate, lower body weight gain (day 4–7, 11–14, 14–16, P\\0.05; overall, day 1–28, P\\0.01), increased plasma alkaline phosphatase (P\\0.05), decreased plasma urea (P\\0.05) and lower absolute (P\\0.01) and relative (P\\0.05) thymus...

  13. Car sequencing is NP-hard: a short proof

    OpenAIRE

    B Estellon; F Gardi

    2013-01-01

    In this note, a new proof is given that the car sequencing (CS) problem is NP-hard. Established from the Hamiltonian Path problem, the reduction is direct while closing some gaps remaining in the previous NP-hardness results. Since CS is studied in many operational research courses, this result and its proof are particularly interesting for teaching purposes.

  14. Functional coatings: the sol-gel approach

    International Nuclear Information System (INIS)

    Belleville, Ph.

    2010-01-01

    CEA's sol-gel laboratory is specialized in the development of innovative sol-gel optical coatings and has extended its application field to membrane materials and coatings for energy conversion, to electric coatings for microelectronics devices and to thin films for gas sensing. This article describes, by way of examples, the laboratory's research on sol-gel functional coatings, including nano-material synthesis, organic-inorganic hybrid-based solution preparation as well as deposition process development and prototyping. (author)

  15. Plasmonic photocatalysts based on silver nanoparticles - layered double hydroxides for efficient removal of toxic compounds using solar light

    Science.gov (United States)

    Gilea, Diana; Radu, Teodora; Muresanu, Mihaela; Carja, Gabriela

    2018-06-01

    Plasmon-enhanced photocatalysis holds important promise for chemical processes and outcomes. We present here the self-assemblies of silver nanoparticles (AgNP)/layered double hydroxides (LDHs: MeAlLDHs with Me2+ = Zn2+;Mg2+) and their derived AgNP/MMOs (type AgNP/MgAl2O4; AgNP/ZnO/ZnAl2O4) as novel plasmonic photocatalysts exhibiting activity for phenol photodegradation from aqueous solution by solar-light. The fabrication procedure of AgNP/LDHs assemblies is simple and cost effective and is based on the in-situ synthesis of AgNP on the LDHs matrices during the reconstruction of MgAlLDH and ZnAlLDH in the aqueous solution of Ag2SO4. The tested catalysts were thoroughly investigated - techniques to obtain information on their crystalline structure (XRD), surface properties (XPS), morphological features (TEM) and optical properties (UV-vis). The results show that the solar photocatalytic response of the catalysts is ascribed to the plasmonic response of AgNP though the catalytic efficiency is strongly influenced by the composition of the MeAlLDHs. The best photocatalytic performance was obtained on AgNP/ZnAlLDH750 catalyst that degraded 100% of phenol after 80 min of irradiation with solar light. The results reveal the high potential to tailor AgNP/LDHs and AgNP/MMOs as efficient photo-functional plasmonic hybrids for waste-water cleaning.

  16. DNA-dependent protein kinase modulates the anti-cancer properties of silver nanoparticles in human cancer cells.

    Science.gov (United States)

    Lim, Hui Kheng; Gurung, Resham Lal; Hande, M Prakash

    2017-12-01

    Silver nanoparticles (Ag-np) were reported to be toxic to eukaryotic cells. These potentially detrimental effects of Ag-np can be advantageous in experimental therapeutics. They are currently being employed to enhance the therapeutic efficacy of cancer drugs. In this study, we demonstrate that Ag-np treatment trigger the activation of DNA-PKcs and JNK pathway at selected doses, presumably as a physiologic response to DNA damage and repair in normal and malignant cells. Ag-np altered the telomere dynamics by disrupting the shelterin complex located at the telomeres and telomere lengths. The genotoxic effect of Ag-np was not restricted to telomeres but the entire genome as Ag-np induced γ-H2AX foci formation, an indicator of global DNA damage. Inhibition of DNA-PKcs activity sensitised the cancer cells towards the cytotoxicity of Ag-np and substantiated the damaging effect of Ag-np at telomeres in human cancer cells. Abrogation of JNK mediated DNA repair and extensive damage of telomeres led to greater cell death following Ag-np treatment in DNA-PKcs inhibited cancer cells. Collectively, this study suggests that improved anti-proliferative and cytotoxic effects of Ag-np treatment in cancer cells can be achieved by the inhibition of DNA-PKcs. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Low concentration NP preoxidation condition for PWR decontamination

    International Nuclear Information System (INIS)

    Huang Fuduan; Yu Degui; Lu Jingju; Ding Dejun; Zhao Yukun

    1991-02-01

    To use preoxidation condition with low concentration NP (nitric acid permanganate) instead of conventional high concentration AP (alkline permanganate ) for PWR oxidation decontamination (POD) was summarized. Experiments including three parts have been performed. The defilming performance and decontamination factor of preoxidation with low concentration NP, which is 100, 10 times lower than that of AP are better than that with high concentration AP. The reason has been studied with the aid of prefilmed specimens of corrosion potential measuring in NP solution and chromium release in NP and AP solutions. The behaviour of alloy 13 prefilmed specimen in NP preoxidation solution is different from 18-8 ss and Incoloy 800. In the low acidity, the corrosion potential moves toward positive direction as the acidity becomes high

  18. Sorption and Migration Mechanisms of 237 Np through Sandy Soil

    International Nuclear Information System (INIS)

    Chantaraprachoom, Nanthavan; Tanaka, Tadao

    2003-06-01

    In order to evaluate migration behavior of radioactive nuclides in the disposal of low-level radioactive waste into a shallow land burial, the sorption characteristic and migration behavior of 237 Np through sandy soil was studied. Two experimental methods were performed by using batch and column systems. The distribution coefficients (K d ) obtained from the adsorption and desorption process are rather small about 16 and 21 cm 3 /g respectively. Size distribution of 237 Np species in the influent solution was measured by ultra-filtration technique. Migration mechanism of 237 Np was studied by column experiments. The experimental condition was the influence of volume of eluting solution; 100, 300, 500, 1000 and 2000 ml respectively. The result from five column experiments confirm that the sorption characteristics of 237 Np are mainly controlled by a reversible ion-exchange reaction and the migration of 237 Np in the sandy soil can be estimated by using the K d concept

  19. Green Synthesis of Silver Nanoparticles Using Sodium Alginate and Lignosulphonic Acid Blends

    Science.gov (United States)

    Thakur, Amrita; Reddy, Giridhar

    2017-08-01

    A simple method based on the principles of green chemistry has been developed to synthesize stable silver nanoparticles (AgNP) for possible biomedical applications. Blend of sodium alginate (SA) and lignosulphonic acid (LS) prepared in the ratio of 80/20 mass percent respectively was used as reducing and stabilizing agent. This blend is biocompatible and has shown drug release ability under physiological conditions. Use of blend has an added advantage as LS has the ability to reduce silver while the blend matrix acts as a stabilizing agent. Effect of precursor concentration (AgNO3) and temperature was investigated. Progress of synthesis was monitored using UV-Vis spectroscopy. Higher temperature and lower silver nitrate concentration showed better synthesis of AgNP.

  20. Hybrid sol-gel optical materials

    Science.gov (United States)

    Zeigler, John M.

    1992-01-01

    Hybrid sol-gel materials comprise silicate sols cross-linked with linear polysilane, polygermane, or poly(silane-germane). The sol-gel materials are useful as optical identifiers in tagging and verification applications and, in a different aspect, as stable, visible light transparent non-linear optical materials. Methyl or phenyl silicones, polyaryl sulfides, polyaryl ethers, and rubbery polysilanes may be used in addition to the linear polysilane. The linear polymers cross-link with the sol to form a matrix having high optical transparency, resistance to thermooxidative aging, adherence to a variety of substrates, brittleness, and a resistance to cracking during thermal cycling.

  1. Multifunctional silver nanoparticle-doped silica for solid-phase extraction and surface-enhanced Raman scattering detection

    Science.gov (United States)

    Markina, Natalia E.; Markin, Alexey V.; Zakharevich, Andrey M.; Gorin, Dmitry A.; Rusanova, Tatiana Yu.; Goryacheva, Irina Yu.

    2016-12-01

    Multifunctional silica gel with embedded silver nanoparticles (SiO2-AgNP) is proposed for application as sorbent for solid-phase extraction (SPE) and simultaneously as substrate for surface-enhanced Raman spectroscopy (SERS) due to their high sorption properties and ability to enhance Raman signal (SERS-active sorbents). SiO2-AgNP was synthesized via alkaline hydrolysis of tetraethyl orthosilicate with simultaneous reduction of silver ions to silver nanoparticles (AgNP) within the SiO2 bulk. Synthesis of AgNP directly to the SiO2 matrix enables to exclude any additional stabilizers for the nanoparticles that educes signal-to-noise ratio during SERS measurement. Apart from Raman spectroscopy, obtained sorbents were also characterized by scanning electron microscopy and UV-visible diffuse reflectance spectroscopy. The influence of AgNO3 concentration used during the SiO2-AgNP synthesis on its gelling time, color, diffuse reflectance spectra, and enhancement of Raman signal was investigated. A Raman enhancement factor of SiO2-AgNP with optimal composition was around 105. Finally, the sorbents were applied for SPE and subsequent SERS detection of model compounds (rhodamine 6G and folic acid). It was found that SPE enables to decrease detectable concentrations by two orders. Therefore, SPE combined with SERS has high potential for further analytical investigations.

  2. Multifunctional silver nanoparticle-doped silica for solid-phase extraction and surface-enhanced Raman scattering detection

    Energy Technology Data Exchange (ETDEWEB)

    Markina, Natalia E.; Markin, Alexey V., E-mail: av-markin@mail.ru; Zakharevich, Andrey M.; Gorin, Dmitry A.; Rusanova, Tatiana Yu.; Goryacheva, Irina Yu. [Saratov State University (Russian Federation)

    2016-12-15

    Multifunctional silica gel with embedded silver nanoparticles (SiO{sub 2}–AgNP) is proposed for application as sorbent for solid-phase extraction (SPE) and simultaneously as substrate for surface-enhanced Raman spectroscopy (SERS) due to their high sorption properties and ability to enhance Raman signal (SERS-active sorbents). SiO{sub 2}–AgNP was synthesized via alkaline hydrolysis of tetraethyl orthosilicate with simultaneous reduction of silver ions to silver nanoparticles (AgNP) within the SiO{sub 2} bulk. Synthesis of AgNP directly to the SiO{sub 2} matrix enables to exclude any additional stabilizers for the nanoparticles that educes signal-to-noise ratio during SERS measurement. Apart from Raman spectroscopy, obtained sorbents were also characterized by scanning electron microscopy and UV-visible diffuse reflectance spectroscopy. The influence of AgNO{sub 3} concentration used during the SiO{sub 2}–AgNP synthesis on its gelling time, color, diffuse reflectance spectra, and enhancement of Raman signal was investigated. A Raman enhancement factor of SiO{sub 2}–AgNP with optimal composition was around 10{sup 5}. Finally, the sorbents were applied for SPE and subsequent SERS detection of model compounds (rhodamine 6G and folic acid). It was found that SPE enables to decrease detectable concentrations by two orders. Therefore, SPE combined with SERS has high potential for further analytical investigations.

  3. Monolayer nanoparticle-covered liquid marbles derived from a sol-gel coating

    Science.gov (United States)

    Li, Xiaoguang; Wang, Yiqi; Huang, Junchao; Yang, Yao; Wang, Renxian; Geng, Xingguo; Zang, Duyang

    2017-12-01

    A sol-gel coating consisting of hydrophobic SiO2 nanoparticles (NPs) was used to produce monolayer NP-covered (mNPc) liquid marbles. The simplest approach was rolling a droplet on this coating, and an identifiable signet allowed determination of the coverage ratio of the resulting liquid marble. Alternatively, the particles were squeezed onto a droplet surface with two such coatings, generating surface buckling from interfacial NP jamming, and then a liquid marble was produced via a jamming-relief process in which water was added into the buckled droplet. This process revealed an ˜7% reduction in particle distance after interfacial jamming. The mNPc liquid marbles obtained by the two methods were transparent with smooth profiles, as naked droplets, and could be advantageously used in fundamental and applied researches for their unique functions.

  4. Sol-gel process for preparing YBa2Cu4O8 precursors from Y, Ba, and Cu acidic acetates/ammonia/ascorbic acid systems

    International Nuclear Information System (INIS)

    Deptula, A.; Lada, W.; Olczak, T.; Goretta, K.C.

    1995-08-01

    Sols were prepared by addition of ammonia to acidic acetate solutions of Y 3+ , Ba 2+ , and Cu 2+ . Ascorbic acid was added to a part of the sol. The resultant sols were gelled to a shard, a film, or microspheres by evaporation at 60 C or by extraction of water from drops of emulsion suspended in 2-ethylhexanol-1. Addition of ethanol to the sols facilitated the formation of gel films, fabricated by a dipping technique, on glass or silver substrates. At 100 C, gels that were formed in the presence of ascorbic acid were perfectly amorphous, in contrast to the crystalline acetate gels. Conversion of the amorphous ascorbate gels to final products was easier than for the acetate gels. The quality of coatings prepared from ascorbate gels was superior to that of acetate gel coatings

  5. Np Incorporation into Uranyl Alteration Phases: A Quantum Mechanical Approach

    International Nuclear Information System (INIS)

    L.C. Huller; R.C. Win; U.Ecker

    2006-01-01

    Neptunium is a major contributor to the long-term radioactivity in a geologic repository for spent nuclear fuel (SNF) due to its long half-life (2.1 million years). The mobility of Np may be decreased by incorporation into the U 6+ phases that form during the corrosion of SNF. The ionic radii of Np (0.089nm) and U (0.087nm) are similar, as is their chemistry. Experimental studies have shown Np can be incorporated into uranyl phases at concentrations of ∼ 100 ppm. The low concentration of Np in the uranyl phases complicates experimental detection and presents a significant challenge for determining the incorporation mechanism. Therefore, we have used quantum mechanical calculations to investigate incorporation mechanisms and evaluate the energetics of Np substituting for U. CASTEP, a density functional theory based code that uses plane waves and pseudo-potentials, was used to calculate optimal H positions, relaxed geometry, and energy of different uranyl phases. The incorporation energy for Np in uranyl alteration phases was calculated for studtite, [(UO 2 )O 2 (H 2 O) 2 ](H 2 ) 2 , and boltwoodite, HK(UO 2 )(SiO 4 )* 1.5(H 2 O). Studtite is the rare case of a stable uranyl hydroxyl-peroxide mineral that forms in the presence of H 2 O 2 from the radiolysis of H 2 O. For studtite, two incorporation mechanisms were evaluated: (1) charge-balanced substitution of Np 5+ and H + for one U 6+ , and (2) direct substitution of Np 6+ for U 6+ . For boltwoodite, the H atomic positions prior to Np incorporation were determined, as well as the Np incorporation mechanisms and the corresponding substitution energies. The preferential incorporation of Np into different structure types of U 6+ minerals was also investigated. Quantum mechanical substitution energies have to be derived at Np concentrations higher than the ones found in experiments or expected in a repository. However, the quantum mechanical results are crucial for subsequent empirical force-field and Monte

  6. Colloidal behavior of Np(V) in aqueous systems

    International Nuclear Information System (INIS)

    Zhao Xin; Zhang Yingjie; Wei Liansheng; Lin Zhangji

    2004-01-01

    The speciation of Np(V) in solutions is measured by means of FT-Raman spectrometer. The formation of colloid of Np(V) in aqueous solutions is studied with the variation of pH(2-12), ionic strength (0.01 mol/L, 0.1 mol/L, 1.0 mol/L), storage time (6h, 30h, 1 week, 6 weeks) and neptunium concentration. The adsorption behavior of Np(V) on granite and its rock-forming minerals (quartz, microcline, albite, biotite and hornblende) is also studied in an aqueous phase of artificial ground water. The experiments are performed at ambient temperature. Experimental results show that a small fraction of Np removed from the solution is adsorbed on the walls of container at the pH above 6 due to the formation of colloid of Np. The formation of colloid of Np depends on its hydrolytic extent, ionic strength, and storage time. The adsorption of Np on granite and the individual mineral depends strongly on the formation of the colloids with the variation of pH in solutions. (author)

  7. Chloride ion-dependent surface-enhanced Raman scattering study of biotin on the silver surface

    International Nuclear Information System (INIS)

    Liu Fangfang; Gu Huaimin; Yuan Xiaojuan; Dong Xiao; Lin Yue

    2011-01-01

    In the present paper, the surface enhanced Raman scattering (SERS) technique was employed to study the SERS spectra of biotin molecules formed on the silver surface. The adsorption geometries of biotin molecules on the silver surface were analyzed based on the SERS data. It can be found that most vibration modes show a Raman shift in silver sol after the addition of sodium chloride solution. In addition, The Raman signals of biotin become weaker and weaker with the increase of the concentration of sodium chloride. This may be due to that the interaction between chloride ions and silver particles is stronger than the interaction between biotin molecules and silver particles. When the concentration of sodium chloride in silver colloid is higher than 0.05mol/L, superfluous chloride ions may form an absorption layer so that biotin can not be adsorbed on silver surface directly. The changes in intensity and profile shape in the SERS spectra suggest different adsorption behavior and surface-coverage of biotin on silver surface. The SERS spectra of biotin suggest that the contribution of the charge transfer mechanism to SERS may be dominant.

  8. Asymmetric flow field-flow fractionation of manufactured silver nanoparticles spiked into soil solution.

    Science.gov (United States)

    Koopmans, G F; Hiemstra, T; Regelink, I C; Molleman, B; Comans, R N J

    2015-05-01

    Manufactured metallic silver nanoparticles (AgNP) are intensively utilized in consumer products and this will inevitably lead to their release to soils. To assess the environmental risks of AgNP in soils, quantification of both their concentration and size in soil solution is essential. We developed a methodology consisting of asymmetric flow field-flow fractionation (AF4) in combination with on-line detection by UV-vis spectroscopy and off-line HR-ICP-MS measurements to quantify the concentration and size of AgNP, coated with either citrate or polyvinylpyrrolidone (PVP), in water extracts of three different soils. The type of mobile phase was a critical factor in the fractionation of AgNP by AF4. In synthetic systems, fractionation of a series of virgin citrate- and PVP-coated AgNP (10-90 nm) with reasonably high recoveries could only be achieved with ultrahigh purity water as a mobile phase. For the soil water extracts, 0.01% (w:v) sodium dodecyl sulfate (SDS) at pH 8 was the key to a successful fractionation of the AgNP. With SDS, the primary size of AgNP in all soil water extracts could be determined by AF4, except for PVP-coated AgNP when clay colloids were present. The PVP-coated AgNP interacted with colloidal clay minerals, leading to an overestimation of their primary size. Similar interactions between PVP-coated AgNP and clay colloids can take place in the environment and facilitate their transport in soils, aquifers, and surface waters. In conclusion, AF4 in combination with UV-vis spectroscopy and HR-ICP-MS measurements is a powerful tool to characterize AgNP in soil solution if the appropriate mobile phase is used. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Block Gas Sol Unit in Haderslev

    DEFF Research Database (Denmark)

    Vejen, Niels Kristian

    2000-01-01

    Investigation of a SDHW system based on a Block Gas Sol Unit from Baxi A/S installed by a consumer i Haderslev, Denmark.......Investigation of a SDHW system based on a Block Gas Sol Unit from Baxi A/S installed by a consumer i Haderslev, Denmark....

  10. Fast Processing of Sol-Gel TCO

    NARCIS (Netherlands)

    Deelen, J. van; Rem, M.; Arfsten, N.; Buskens, P.P.

    2016-01-01

    TCOs are usually deposited using sputtering or chemical vapor deposition, which have a yield of typically 50-75%. The sol gel method does not need low pressure and can be done with a high precursor yield in the range of 90 – 100%. Sol gel enables also the TCO function as a planarization or

  11. Towards experiments at the new ELI-NP facility

    Directory of Open Access Journals (Sweden)

    Balabanski D. L.

    2014-01-01

    Full Text Available The Extreme Light Infrastructure (ELI Pan-European initiative represents a major step forward in quest for extreme electromagnetic fields. The Extreme Light Infrastructure – Nuclear Physics (ELI-NP laboratory is one of the three pillars of the ELI project, that aims to use such extreme electromagnetic fields for nuclear physics and quantum electrodynamics research. At ELI-NP two ten petawatt high-power laser systems together with a very brilliant narrow-width γ beam are the main research tools. Here the current status of the project and the experimental program related to nuclear research, which is under preparation at ELI-NP, are presented.

  12. Copper and silver halates

    CERN Document Server

    Woolley, EM; Salomon, M

    2013-01-01

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

  13. Dissociation behavior of Np(IV) from humic acid colloid

    Energy Technology Data Exchange (ETDEWEB)

    Iijima, K.; Tobitsuka, S. [Japan Nuclear Cycle Development Institute, 4-33 Muramatsu, Tokai, Naka-gun, Ibaraki 319-1194 (Japan); Kohara, Y. [Inspection Development Corporation, 4-33, Muramatsu, Tokai, Nakagun, Ibaraki 319-1112 (Japan)

    2005-07-01

    Full text of publication follows: Dissociation behavior of Np(IV) from humic colloid, which was prepared with purified Aldrich humic acid (PAHA) was investigated. The complexation experiments were carried out in 0.1 M NaClO{sub 4} - 0.05 M Na{sub 2}S{sub 2}O{sub 4} solution at pH 8 with PAHA concentration between 0 and 500 mg L-1 under anaerobic condition. Np-237 was added as Np(V) solution so that its concentration becomes 1.1 x 10-5 mol L-1. After shaking from 1 to 156 days, aliquots of experimental solution were filtered through the membranes with 50, 10 and 3 kD of MWCO to obtain the size distribution of colloid, followed by adding the filtrate into the 6 M HCl for dissociation. At the end of experiments for 596 days, 0.1 M NaHCO{sub 3} was used for dissociation solution. The concentration of Np released into this solution was evaluated by measuring a activity of Np-237. The concentration of Np becomes constant by 112 days. Since Eh of the solution has been kept between -300 and -100 mV vs. SHE during experimental duration, Np is presumed to be reduced into tetravalent. In the case of higher PAHA concentration than 50 mg L{sup -1}, the Np concentration is close to that of initially added Np. Since the size of the dissolved species of Np during complexation experiments varies from 3 to 50 kD, the Np is sorbed on humic acid colloid. In the dissociation experiments, the Np dissociated by 6 M HCl decreases with increasing complexation time and PAHA concentration. After 156 days complexation with 500 mg L{sup -1} of PAHA, 35% of Np can be dissociated from the colloid. Such a tendency, however, is not observed in case of the lowest PAHA concentration, 5 mg L{sup -1}. After 596 days complexation, the dissociation experiments were carried out by adding 0.1 M NaHCO{sub 3} solution to avoid the precipitation which might hinder the dissociation of Np in the aforementioned experiments with HCl. As a result, 50% of Np is dissociated in the presence of 50 and 100 mg L-1 of

  14. Green Synthesis of Silver Nanoparticles and the Study of Optical Properties

    Directory of Open Access Journals (Sweden)

    Ramakrishna Vasireddy

    2012-08-01

    Full Text Available The synthesis of silver nanoparticles of varying size has been achieved using different molar concentrations of NaOH while the effect of changing the temperature has been studied. AgNO3, gelatine, glucose and NaOH are used as a silver precursor, stabilizer, reducing agent and accelerator respectively. The synthesized nanoparticles have been characterized by a FESEM study, X‐ray diffractometry, Raman spectroscopy and UV‐vis spectroscopy. The colloidal sols of the silver nanoparticles in a biopolymer gelatine show strong surface plasmon resonance absorption peaks. The visible photoluminescence emission from the synthesized silver nanocrystals has been recorded within the wavelength range of 400‐600 nm under UV excitation. The synthesized nanoparticles may be extremely useful in making biosensor devices as well as for other applications.

  15. A study on enhancement of Np extraction by TBP through the electrochemical adjustment of Np valance by using a glassy carbon fiber column electrode system

    International Nuclear Information System (INIS)

    Kim, K. W.; Song, K. C.; Lee, I. H.; Choi, I. K.; Yoo, J. H.

    1999-01-01

    The Np valance state in nitric acid and the effect of nitrous acid on the Np valance composition were studied through ways of absorbance by spectrophotometer, extraction by TBP, and electrochemistry. Enhancement of Np extraction to 30 vol.% TBP was carried out through adjustment of Np valance state by using a glassy carbon fiber column electrode system. The Np solution used in this work consisted of only Np(V) and Np(VI) without Np(IV). The composition of Np(V) in the range of 0.5M ∼ 5.5 M nitric acid was 32% ∼ 19%. The electrolytic oxidation of Np(V) coexisting with Np(VI) in the solution enhanced Np extraction by 30 vol.% TBP about five times more than the one without the electrolytic oxidation. The facts were confirmed that the nitrous acid of less than about 10 -5 M acted as a catalyst to accelerate the chemical oxidation reaction of Np(V) to Np(VI) and the nitrous acid of more than 10 -3 M reduced Np(VI) to Np(V) reversely

  16. Quantitative characterization of colloidal assembly of graphene oxide-silver nanoparticle hybrids using aerosol differential mobility-coupled mass analyses.

    Science.gov (United States)

    Nguyen, Thai Phuong; Chang, Wei-Chang; Lai, Yen-Chih; Hsiao, Ta-Chih; Tsai, De-Hao

    2017-10-01

    In this work, we develop an aerosol-based, time-resolved ion mobility-coupled mass characterization method to investigate colloidal assembly of graphene oxide (GO)-silver nanoparticle (AgNP) hybrid nanostructure on a quantitative basis. Transmission electron microscopy (TEM) and zeta potential (ZP) analysis were used to provide visual information and elemental-based particle size distributions, respectively. Results clearly show a successful controlled assembly of GO-AgNP by electrostatic-directed heterogeneous aggregation between GO and bovine serum albumin (BSA)-functionalized AgNP under an acidic environment. Additionally, physical size, mass, and conformation (i.e., number of AgNP per nanohybrid) of GO-AgNP were shown to be proportional to the number concentration ratio of AgNP to GO (R) and the selected electrical mobility diameter. An analysis of colloidal stability of GO-AgNP indicates that the stability increased with its absolute ZP, which was dependent on R and environmental pH. The work presented here provides a proof of concept for systematically synthesizing hybrid colloidal nanomaterials through the tuning of surface chemistry in aqueous phase with the ability in quantitative characterization. Graphical Abstract Colloidal assembly of graphene oxide-silver nanoparticle hybrids characterized by aerosol differential mobility-coupled mass analyses.

  17. Permanent Habitats in Earth-Sol/Mars-Sol Orbit Positions

    Science.gov (United States)

    Greenspon, J.

    Project Outpost is a manned Earth-Sol/Mars-Sol platform that enables permanent occupation in deep space. In order to develop the program elements for this complex mission, Project Outpost will rely primarily on existing/nearterm technology and hardware for the construction of its components. For the purposes of this study, four mission requirements are considered: 1. Outpost - Man's 1st purpose-produced effort of space engineering, in which astructure is developed/constructed in an environment completely alien to currentpractices for EVA guidelines. 2. Newton - a concept study developed at StarGate Research, for the development ofa modified Hohmann personnel orbital transport operating between Earth andMars. Newton would serve as the primary crew delivery apparatus throughrepeatable transfer scheduling for all Earth-Lpoint-Mars activities. Thispermanent "transit system" would establish the foundations for Solar systemcolonization. 3. Cruis - a concept study developed at StarGate Research, for the development of amodified Hohmann cargo orbital transport operating between Earth and Mars.Cruis would serve as the primary equipment delivery apparatus throughrepeatable transfer scheduling for all Earth-Lpoint-Mars activities. Thispermanent "transit system" would establish the foundations for Solar systemcolonization, and 4. Ares/Diana - a more conventional space platform configuration for Lunar andMars orbit is included as a construction baseline. The operations of these assetsare supported, and used for the support, of the outpost. Outpost would be constructed over a 27-year period of launch opportunities into Earth-Sol or Mars-Sol Lagrange orbit (E-S/M-S L1, 4 or 5). The outpost consists of an operations core with a self-contained power generation ability, a docking and maintenance structure, a Scientific Research complex and a Habitation Section. After achieving initial activation, the core will provide the support and energy required to operate the outpost in a 365

  18. The effects of food availability on growth and reproduction of Daphnia magna exposed to silver nanoparticles

    DEFF Research Database (Denmark)

    Mackevica, Aiga; Skjolding, Lars Michael; Gergs, A.

    ) were performed using 30 nm citric acid stabilized AgNP. The aim of the study was, besides providing data for the chronic toxicity of AgNP, to study the influence of the food availability on the reproductive toxicity of AgNP in Daphnia magna. The exposure concentrations applied ranged from 2 to 50 μg...... to controls, whereas concentrations above 10 μgAg/L resulted in inhibition of growth and reproduction as well as an increased mortality. The addition of higher amounts of food showed a beneficial effect on animal survival, growth and reproduction. Similar as in normal food availability treatment, animals......The number of available studies on the acute effects of silver nanoparticles (AgNP) on aquatic organisms has increased dramatically in recent years, but there is still very limited information available on chronic effects. In this study, a series of Daphnia magna 21-days reproduction test (OECD 211...

  19. Silver release from nanocomposite Ag/alginate hydrogels in the presence of chloride ions: experimental results and mathematical modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kostic, Danijela, E-mail: dkostic@tmf.bg.ac.rs [Innovation Center of the Faculty of Technology and Metallurgy (Serbia); Vidovic, Srđan, E-mail: srdjanhi@gmail.com; Obradovic, Bojana, E-mail: bojana@tmf.bg.ac.rs [University of Belgrade, Faculty of Technology and Metallurgy (Serbia)

    2016-03-15

    A stepwise experimental and mathematical modeling approach was used to assess silver release from nanocomposite Ag/alginate microbeads in wet and dried forms into water and into normal saline solution chosen as a simplified model for certain biological fluids (e.g., blood plasma, wound exudates, sweat, etc). Three phenomena were connected and mathematically described: diffusion of silver nanoparticles (AgNPs) within the alginate hydrogel, AgNP oxidation/dissolution and reaction with chloride ions, and diffusion of the resultant silver-chloride species. Mathematical modeling results agreed well with the experimental data with the AgNP diffusion coefficient estimated as 1.3 × 10{sup −18} m{sup 2} s{sup −1}, while the first-order kinetic rate constant of AgNP oxidation/dissolution and diffusivity of silver-chloride species were shown to be inversely related. In specific, rapid rehydration and swelling of dry Ag/alginate microbeads induced fast AgNP oxidation/dissolution reaction with Cl{sup −} and AgCl precipitation within the microbeads with the lowest diffusivity of silver-chloride species compared to wet microbeads in normal saline. The proposed mathematical model provided an insight into the phenomena related to silver release from nanocomposite Ca-alginate hydrogels relevant for use of antimicrobial devices and established, at the same time, a basis for further in-depth studies of AgNP interactions in hydrogels in the presence of chloride ions.

  20. Surface plasmon resonances, optical properties, and electrical conductivity thermal hystersis of silver nanofibers produced by the electrospinning technique.

    Science.gov (United States)

    Barakat, Nasser A M; Woo, Kee-Do; Kanjwal, Muzafar A; Choi, Kyung Eun; Khil, Myung Seob; Kim, Hak Yong

    2008-10-21

    In the present study, silver metal nanofibers have been successfully prepared by using the electrospinning technique. Silver nanofibers have been produced by electrospinning a sol-gel consisting of poly(vinyl alcohol) and silver nitrate. The dried nanofiber mats have been calcined at 850 degrees C in an argon atmosphere. The produced nanofibers do have distinct plasmon resonance compared with the reported silver nanoparticles. Contrary to the introduced shapes of silver nanoparticles, the nanofibers have a blue-shifted plasmon resonance at 330 nm. Moreover, the optical properties study indicated that the synthesized nanofibers have two band gap energies of 0.75 and 2.34 eV. An investigation of the electrical conductivity behavior of the obtained nanofibers shows thermal hystersis. These privileged physical features greatly widen the applications of the prepared nanofibers in various fields.

  1. Separation of Np from U and Pu using a salt-free reductant for Np(VI) by continuous counter-current back-extraction

    International Nuclear Information System (INIS)

    Ban, Yasutoshi; Asakura, Toshihide; Morita, Yasuji

    2005-01-01

    Reduction properties of several salt-free reagents for Np(VI) and Pu(IV) were reviewed to choose selective reductants that reduce only Np(VI) to Np(V) for separating Np from U and Pu in TBP by reductive back-extraction. Allylhydrazine was proposed as a candidate for selective Np(VI) reductant, and it was confirmed by a batch experiment that allylhydrazine reduced almost all Np(VI) to Np(V) and back-extracted Np from organic phase (30 vol.% TBP diluted in n-dodecane) to aqueous phase (3 mol/dm 3 HNO 3 ) within 10 min. A continuous counter-current experiment using a miniature mixer-settler was carried out with allylhydrazine at room temperature. At least 91% of Np(VI) that fed to the mixer-settler was selectively reduced to Np(V) and separated from U and Pu. (author)

  2. A re-assessment of the safety of silver in household water treatment: rapid systematic review of mammalian in vivo genotoxicity studies.

    Science.gov (United States)

    Fewtrell, Lorna; Majuru, Batsirai; Hunter, Paul R

    2017-06-20

    Despite poor evidence of their effectiveness, colloidal silver and silver nanoparticles are increasingly being promoted for treating potentially contaminated drinking water in low income countries. Recently, however, concerns have been raised about the possible genotoxicity of particulate silver. The goal of this paper was to review the published mammalian in vivo genotoxicity studies using silver micro and nanoparticles. SCOPUS and Medline were searched using the following search string: ("DNA damage" OR genotox* OR Cytotox* OR Embryotox*) AND (silver OR AgNP). Included papers were any mammalian in vivo experimental studies investigating genotoxicity of silver particles. Studies were quality assessed using the ToxRTool. 16 relevant papers were identified. There were substantial variations in study design including the size of silver particles, animal species, target organs, silver dose, route of administration and the method used to detect genotoxicity. Thus, it was not possible to produce a definitive pooled result. Nevertheless, most studies showed evidence of genotoxicity unless using very low doses. We also identified one human study reporting evidence of "severe DNA damage" in silver jewellery workers occupationally exposed to silver particles. With the available evidence it is not possible to be definitive about risks to human health from oral exposure to silver particulates. However, the balance of evidence suggests that there should be concerns especially when considering the evidence from jewellery workers. There is an urgent need to determine whether people exposed to particulate silver as part of drinking water treatment have evidence of DNA damage.

  3. Magnetic sublattices in Np{sub 2}Co{sub 17} and Np{sub 2}Ni{sub 17}

    Energy Technology Data Exchange (ETDEWEB)

    Colineau, E., E-mail: eric.colineau@ec.europa.eu; Hen, A. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Sanchez, J.-P. [CEA, INAC-SPSMS (France); Griveau, J.-C.; Magnani, N.; Eloirdi, R. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Halevy, I. [Ben Gurion University, Nuclear Engineering Department (Israel); Gaczyński, P. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany); Orion, I. [Ben Gurion University, Nuclear Engineering Department (Israel); Shick, A. B. [Institute of Physics, ASCR (Czech Republic); Caciuffo, R. [Institute for Transuranium Elements (ITU), European Commission, Joint Research Centre (JRC) (Germany)

    2016-12-15

    Rare-earth-based compounds R{sub 2}T{sub 17} (R=Rare earth; T=Transition metal) have been extensively studied and developed for applications as permanent magnets. The actinide-based analogues, however, are much less documented and we report here about the magnetic properties of Np{sub 2}Co{sub 17} and Np{sub 2}Ni{sub 17}, as inferred from {sup 237}Np Mössbauer spectroscopy, the best resonance in actinides, and specific heat.

  4. Complexation of Np(V) in aqueous solutions

    International Nuclear Information System (INIS)

    Askarieh, M.M.; Hansford, M.I.; Staunton, S.; Rees, L.V.C.

    1992-01-01

    Various parameters affecting the diffusion coefficient of neptunium (V) in clay systems have been studied; e.g. clay mineralogy, the charge compensating cation in the clay, the ionic strength of a background perchlorate solution and the presence of three organic ligands. Several well established techniques have been employed to obtain stability constants for the neptunium systems; Np(V)/EDTA and Np(V)/citrate, Np(V)/Aldrich Humic Acid (AHA), Np(V)/Gorleben Humic Acid (GHA) and for the uranium systems U(VI)/EDTA, U(VI)/citrate and U(VI)/AHA. The experimental techniques employed were UV/visible spectroscopy, polarography, solvent extraction and ion exchange. (Author)

  5. Complexation of Np(V) in aqueous solutions

    International Nuclear Information System (INIS)

    Askarieh, M.M.; Hansford, M.I.; Staunton, S.; Rees, L.V.C.

    1993-01-01

    Various parameters affecting the diffusion coefficient of neptunium (V) in clay systems have been studied; e.g. clay mineralogy, the charge compensating cation in the clay, the ionic strength of a background perchlorate solution and the presence of three organic ligands. Several well established techniques have been employed to obtain stability constants for the neptunium systems; Np(V) EDTA and Np(V)/citrate, Np(V)/Aldrich Humic Acid (AHA), Np(V)/Gorleben Hulic Acid (GHA) and for the uranium systems U(VI)/EDTA, U(VI)/citrate and U(VI)/AHA. The experimental techniques employed were UV/visible spectroscopy, polarography, solvent extraction and ion exchange. (author). 50 refs., 24 figs., 9 tabs

  6. Rabbit defensin (NP-1) genetic engineering of plant | Ting | African ...

    African Journals Online (AJOL)

    Rabbit defensin (NP-1) genetic engineering of plant. ... Log in or Register to get access to full text downloads. ... defensin genetic engineering of plant in recent years, and also focuses on the existing problems and new strategies in this area.

  7. Mineral commodity profiles: Silver

    Science.gov (United States)

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

    2005-01-01

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

  8. Toxicokinetics and toxicodynamics of differently coated silver nanoparticles and silver nitrate in Enchytraeus crypticus upon aqueous exposure in an inert sand medium.

    Science.gov (United States)

    Topuz, Emel; van Gestel, Cornelis A M

    2015-12-01

    The aim of the present study was to evaluate the effect of silver nanoparticles (AgNPs) on Enchytraeus crypticus, applying a combined toxicokinetics and toxicodynamics approach to understand the relationship between survival and the development of internal Ag concentrations in the animals over time. Toxicity tests were conducted in medium composed of well-defined aqueous solutions added to inert quartz sand to avoid the complexity of soil conditions. Citrate-coated AgNPs (AgNP-Cit) and polyvinylpyrrolidone-coated AgNPs (AgNP-PVP) were tested and compared with silver nitrate (AgNO3), which was used as a positive control for Ag ion effects. The median lethal concentration (LC50) values based on Ag concentrations in the solution phase of the test medium decreased over time and reached steady state after 7 d, with AgNO3 and AgNP-PVP being more toxic than AgNP-Cit. Slow dissolution may explain the low uptake kinetics and lower toxicity of AgNP-Cit compared with the other 2 Ag forms. The LC50 values based on internal Ag concentrations in the animals were almost stable over time, highlighting the importance of integrating toxicokinetics and toxicodynamics and relating survival with internal Ag concentrations. Neither survival-based elimination rates nor internal LC50s in the organisms showed any significant evidence of nano-specific effects for both AgNPs, although they suggested some uptake of particulate Ag for AgNP-Cit. The authors conclude that the toxicity of both types of AgNP probably is mainly attributable to the release of Ag ions. © 2015 SETAC.

  9. Sol-gel technology for biomedical engineering

    International Nuclear Information System (INIS)

    Podbielska, H.; Ulatowska-Jarza, A.

    2005-01-01

    Sol-gel derived silica possess many promising features, including low-temperature preparation procedure, porosity, chemical and physical stability. Applications exploiting porous materials to encapsulate sensor molecules, enzymes and many other compounds, are developing rapidly. In this paper some potential applications, with emphasis on biomedical and environmental ones, are reviewed. The material preparation procedure is described and practical remarks on silica-based sol-gels are included. It is reported that sol-gels with entrapped various molecules may be used in construction of implants and coatings with bioactive properties. It is shown how to exploit the sol-gel production route for construction of sol-gel coated fiberoptic applicators for laser therapy. The applications of bioactive materials are discussed, as well. It is demonstrated that it is possible to immobilize photosensitive compounds in sol-gel matrix without loosing their photoactivity. Some examples of sol-gel based biosensors are demonstrated, as well, showing their potential for detecting various gases, toxic substances, acidity, humidity, enzymes and biologically active agents. (authors)

  10. Sol-gel bonding of silicon wafers

    International Nuclear Information System (INIS)

    Barbe, C.J.; Cassidy, D.J.; Triani, G.; Latella, B.A.; Mitchell, D.R.G.; Finnie, K.S.; Short, K.; Bartlett, J.R.; Woolfrey, J.L.; Collins, G.A.

    2005-01-01

    Sol-gel bonds have been produced between smooth, clean silicon substrates by spin-coating solutions containing partially hydrolysed silicon alkoxides. The two coated substrates were assembled and the resulting sandwich fired at temperatures ranging from 60 to 600 deg. C. The sol-gel coatings were characterised using attenuated total reflectance Fourier transform infrared spectroscopy, ellipsometry, and atomic force microscopy, while the corresponding bonded specimens were investigated using scanning electron microscopy and cross-sectional transmission electron microscopy. Mechanical properties were characterised using both microindentation and tensile testing. Bonding of silicon wafers has been successfully achieved at temperatures as low as 60 deg. C. At 300 deg. C, the interfacial fracture energy was 1.55 J/m 2 . At 600 deg. C, sol-gel bonding provided superior interfacial fracture energy over classical hydrophilic bonding (3.4 J/m 2 vs. 1.5 J/m 2 ). The increase in the interfacial fracture energy is related to the increase in film density due to the sintering of the sol-gel interface with increasing temperature. The superior interfacial fracture energy obtained by sol-gel bonding at low temperature is due to the formation of an interfacial layer, which chemically bonds the two sol-gel coatings on each wafer. Application of a tensile stress on the resulting bond leads to fracture of the samples at the silicon/sol-gel interface

  11. Green synthesis of silver nanoparticles and silver colloidal solutions

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  12. Structure and bonding in compounds containing the NpO2+ and NpO22+ ions

    International Nuclear Information System (INIS)

    Musikas, C.; Burns, J.H.

    1975-01-01

    Studies of oxo cations of Np(V) and Np(VI) were made on single crystals using X-ray diffraction and spectroscopic methods. Quantitative measurements of the geometry of the triatomic ion and its uranyl(VI) analog made it possible to assess the effects on bond lengths of the nature of equatorial secondary bonds, the change in valence from V to VI, and the actinide contraction. Absorption spectra showed marked changes in the solid state compared to the same ion in solution, especially anisotropy with crystal orientation (dichroism). The compounds analyzed were Na 4 NpO 2 (O 2 ) 3 .9H 2 O, Na 4 UO 2 (O 2 ) 3 .9H 2 O, K 4 NpO 2 (CO 3 ) 3 , and BaNpO 2 (H 3 C 2 O 2 ).2H 2 O. All actinyl ions were found to be linear. The largest difference in M=O bond lengths is between 1.776 in the compound having the relatively weak secondary linkage to carbonate, and 1.843 A in which the peroxide forms much stronger covalent bonds. Between compounds identical except for change of U to Np the M=O bond length contracts by only about 0.01 A. However an elongation of about 0.11A is observed when neptunium(VI) is reduced to neptunium(V) without change in the equatorial ligand. (U.S.)

  13. Applications of sol gel ceramic coatings

    International Nuclear Information System (INIS)

    Barrow, D.

    1996-01-01

    The sol gel method is a chemical technique in which polycrystalline ceramic films are fabricated from a solution of organometallic precursors. The technique is attractive for many industrial applications because it is a simple (films are processed in air), flexible (can be used to coat complex geometries) and cost effective (does not require expensive equipment) process. In addition, dense, high quality coatings can be achieved at much lower temperatures than is generally required for sintering bulk ceramics. In this paper the conventional sol gel method and the new datec process are reviewed and potential applications of sol gel coatings in automotive, aerospace, petrochemical, nuclear and electronic industries are discussed. (orig.)

  14. Reduced Silver Nanoparticle Phytotoxicity in Crambe abyssinica with Enhanced Glutathione Production by Overexpressing Bacterial y-Glutamylcysteine Synthase

    Science.gov (United States)

    Chuanxin Ma; Sudesh Chhikara; Rakesh Minocha; Stephanie Long; Craig Musante; Jason C. White; Baoshan Xing; Om Parkash Dhankher

    2015-01-01

    Silver nanoparticles (Ag NPs) are widely used in consumer products, and their release has raised serious concerns about the risk of their exposure to the environment and to human health. However, biochemical mechanisms by which plants counteract NP toxicity are largely unknown. We have previously engineered Crambe abyssinica plants expressing the...

  15. Greener Techniques for the Synthesis of Silver Nanoparticles Using Plant Extracts, Enzymes, Bacteria, Biodegradable Polymers, and Microwaves

    Science.gov (United States)

    The use of silver nanoparticles (AgNPs) is gaining in popularity due to silver’s antibacterial properties. Conventional methods for AgNP synthesis require dangerous chemicals and large quantities of energy (heat) and can result in formation of hazardous by-products. This article ...

  16. Mass Cytometry for Detection of Silver at the Bacterial Single Cell Level

    Directory of Open Access Journals (Sweden)

    Yuting Guo

    2017-07-01

    Full Text Available Background: Mass cytometry (Cytometry by Time of Flight, CyTOF allows single-cell characterization on the basis of specific metal-based cell markers. In addition, other metals in the mass range such as silver can be detected per cell. Bacteria are known to be sensible to silver and a protocol was developed to measure both the number of affected cells per population and the quantities of silver per cell.Methods: For mass cytometry ruthenium red was used as a marker for all cells of a population while parallel application of cisplatin discriminated live from dead cells. Silver quantities per cell and frequencies of silver containing cells in a population were measured by mass cytometry. In addition, live/dead subpopulations were analyzed by flow cytometry and distinguished by cell sorting based on ruthenium red and propidium iodide double staining. Verification of the cells’ silver load was performed on the bulk level by using ICP-MS in combination with cell sorting. The protocol was developed by conveying both, fast and non-growing Pseudomonas putida cells as test organisms.Results: A workflow for labeling bacteria in order to be analyzed by mass cytometry was developed. Three different parameters were tested: ruthenium red provided counts for all bacterial cells in a population while consecutively applied cisplatin marked the frequency of dead cells. Apparent population heterogeneity was detected by different frequencies of silver containing cells. Silver quantities per cell were also well measurable. Generally, AgNP-10 treatment caused higher frequencies of dead cells, higher frequencies of silver containing cells and higher per-cell silver quantities. Due to an assumed chemical equilibrium of free and bound silver ions live and dead cells were associated with silver in equal quantities and this preferably during exponential growth. With ICP-MS up to 1.5 fg silver per bacterial cell were detected.Conclusion: An effective mass cytometry

  17. Synthesis and Characterization of Optically Active Fractal Seed Mediated Silver Nickel Bimetallic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Joseph Adeyemi Adekoya

    2014-01-01

    Full Text Available The synthesis of new seed mediated AgNi allied bimetallic nanocomposites was successfully carried out by the successive reduction of the metal ions in diethylene glycol, ethylene glycol, glycerol, and pentaerythritol solutions, with concomitant precipitation of Ag/Ni bimetal sols. The optical measurement revealed the existence of distinct band edge with surface plasmon resonance (SPR in the region of 400–425 nm and excitonic emission with maximum peak at 382 nm which were reminiscent of cluster-in-cluster surface enriched bimetallic silver-nickel sols. The morphological characterization by transmission electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction analyses complimented by surface scan using X-ray photoelectron spectroscopy strongly supported the formation of intimately alloyed face-centered silver/nickel nanoclusters.

  18. SERS studies on the interaction between UO22+ and PVP-stabilized silver nanoparticles

    International Nuclear Information System (INIS)

    Roy, M.; Tyagi, A.K.; Kumar, Rakesh; Pandey, A.K.; Goswami, A.

    2010-01-01

    Interaction between uranyl (UO 2 2+ ) ions and silver nanoparticles (Ag-nps) stabilized by suitable polymeric capping agents has been studied in aqueous phase using surface enhanced resonance Raman spectroscopy technique (SERS). Polyvinylpyrrolidone (PVP) stabilized Ag-nps were synthesized by dissolving in water appropriate amount of PVP and AgNO 3 along with a suitable reducing agent in the form of either formamide or sodium borohydride. The solution was vigorously stirred for 5h and finally nanoparticle sols were obtained. A series of analyte samples was prepared by adding an appropriate amount of silver sol to different volumes of uranyl stock solution prepared at pH=3. The solutions were then drop cast on glass slides and dried in air. Preliminary results on drop-cast samples are presented here

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  20. Rapid Colorimetric Detection of Cartap Residues by AgNP Sensor with Magnetic Molecularly Imprinted Microspheres as Recognition Elements

    Directory of Open Access Journals (Sweden)

    Mao Wu

    2018-06-01

    Full Text Available The overuse of cartap in tea tree leads to hazardous residues threatening human health. A colorimetric determination was established to detect cartap residues in tea beverages by silver nanoparticles (AgNP sensor with magnetic molecularly imprinted polymeric microspheres (Fe3O4@mSiO2@MIPs as recognition elements. Using Fe3O4 as supporting core, mesoporous SiO2 as intermediate shell, methylacrylic acid as functional monomer, and cartap as template, Fe3O4@mSiO2@MIPs were prepared to selectively and magnetically separate cartap from tea solution before colorimetric determination by AgNP sensors. The core-shell Fe3O4@mSiO2@MIPs were also characterized by FT-IR, TEM, VSM, and experimental adsorption. The Fe3O4@mSiO2@MIPs could be rapidly separated by an external magnet in 10 s with good reusability (maintained 95.2% through 10 cycles. The adsorption process of cartap on Fe3O4@mSiO2@MIPs conformed to Langmuir adsorption isotherm with maximum adsorption capacity at 0.257 mmol/g and short equilibrium time of 30 min at 298 K. The AgNP colorimetric method semi-quantified cartap ≥5 mg/L by naked eye and quantified cartap 0.1–5 mg/L with LOD 0.01 mg/L by UV-vis spectroscopy. The AgNP colorimetric detection after pretreatment with Fe3O4@mSiO2@MIPs could be successfully utilized to recognize and detect cartap residues in tea beverages.

  1. Novel synthesis of Prussian blue nanoparticles and nanocomposite sol: Electro-analytical application in hydrogen peroxide sensing

    International Nuclear Information System (INIS)

    Pandey, Prem C.; Pandey, Ashish K.

    2013-01-01

    Highlights: ► Novel process for the synthesis of PBNPs sol of 15.8 nm size is reported. ► The PBNPs sol shows the electron transfer rate constant to the order of 32.1 s −1 ► The PBNPs sol has shown the functional activity for making the nanocomposite. ► The nanocomposite with tris(2,2′-bipyridyl)ruthenium shows photoluminiscent ability. ► The PBNPs and its nanocomposite (PB-Rubpy) show high sensitivity for H 2 O 2 sensing. - Abstract: This paper reports a new method for the synthesis of Prussian blue nanoparticles (PBNPs) sol of homogeneous dispersion with average particle size to the order of 15.8 nm. The new method of PBNPs sol synthesis is based on the interaction of active concentrations of 3-aminopropylalkoxysilane, cyclohexanone and single precursor potassium ferricyanide under ambient conditions. The PBNPs sol shows excellent electrochemistry with electron transfer rate constant to the order of 32.1 s −1 . The resulting PBNPs sol has been found highly stable for practical applications and shows functional activity for making nanocomposite sol with tris(2,2′-bipyridyl) ruthenium (Rubpy). The PB-Rubpy nanocomposite shows high sensitivity for H 2 O 2 electrochemical sensing to the order of 1102.0 μA mM −1 cm −2 and storage stability of the materials for more than 3 months. In addition, these nanocomposite exhibits excellent electrocatalytic property for hydrogen peroxide (H 2 O 2 ) sensing with catalytic rate constant to the order of 3.14 × 10 3 M −1 s −1 . The PB-Rubpy nanocomposite sol, apart from electrocatalytic application, shows photoluminiscent ability for many opto-electroanalytical applications. In addition to that functional property of PBNPs sol for making nanodispersion with several known nanoparticles of gold, silver, palladium along with in situ synthesis of mixed metal hexacyanoferrate have also been observed.

  2. Effect of silver nanoparticle coatings on mycobacterial biofilm attachment and growth: Implications for ceramic water filters

    Science.gov (United States)

    Larimer, Curtis James

    Silver is a natural, broad-spectrum antibacterial metal and its toxicity can be enhanced when surface area is maximized. As a result, silver nanoparticles (AgNP) have been investigated for use in novel water treatment technologies. The hypothesis of this work is that deposited AgNPs can enhance water treatment technologies by inhibiting growth of planktonic bacteria and biofilms. This was investigated by evaluating the antibacterial efficacy of AgNPs both in solution and as deposited on surfaces. AgNPs were found to be toxic to three species of environmental mycobacteria, M. smegmatis, M. avium, and M. marinum and the level of susceptibility varied widely, probably owing to the varying levels of silver that each species is exposed to in its natural environment. When cultured in a AgNP enriched environment M. smegmatis developed resistance to the toxic effects of both the nanoparticles and silver ions. The resistant mutant was as viable as the unmodified strain and was also resistant to antibiotic isoniazid. However, the strain was more susceptible to other toxic metal ions from ZnSO4 and CuSO4. AgNPs were deposited on silicon wafer substrates by vertical colloidal deposition (VCD). Manipulating deposition speed and also concentration of AgNPs in the depositing liquid led to a range of AgNP coatings with distinctive deposition lines perpendicular to the motion of the meniscus. Experimental results for areal coverage, which was measured from SEM images of AgNP coatings, were compared to Diao's theory of VCD but did not show agreement due to a stick-slip mechanism that is not accounted for by the theory. Durability of AgNP coatings is critical for antibacterial efficacy and to mitigate the risks of exposing the environment to nanomaterials and it was measured by exposing AgNP coatings to liquid flow in a flow cell. Durability was improved by modifying processing to include a heat treatment after deposition. Finally, the antibiofilm efficacy of deposited AgNPs was

  3. Current Development of Silver Nanoparticle Preparation, Investigation, and Application in the Field of Medicine

    International Nuclear Information System (INIS)

    Murphy, M.; Ting, K.; Zhang, X.; Zheng, Z.; Ting, K.; Soo, Ch.; Zheng, Z.

    2014-01-01

    The invited review covers different research areas of silver nanoparticles (AgNPs), including the synthesis strategies of AgNPs, antimicrobial and anti-inflammatory properties of AgNPs, osteoconductive and osteoinductive activities of AgNP-based materials, and potential toxicity of AgNPs. The potential mechanisms of AgNP’s biological efficacy as well as its potential toxicity are discussed as well. In addition, the current development of AgNP applications, especially in the area of therapeutics, is also summarized.

  4. Sol-gel antireflective coating on plastics

    Science.gov (United States)

    Ashley, Carol S.; Reed, Scott T.

    1990-01-01

    An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

  5. Third Order Susceptibility of Platinum Sulfide Sol

    National Research Council Canada - National Science Library

    LaiHing, Kenneth

    1992-01-01

    .... Experimentally this is determined using degenerate four-wave mixing (DFWM). Pure sulfur sol was prepared by dissolving the solid sulfur in hydrazine, followed by addition of distilled water with vigorous stirring...

  6. Activated carbon from pyrolysed sugarcane bagasse: Silver nanoparticle modification and ecotoxicity assessment

    Energy Technology Data Exchange (ETDEWEB)

    Gonçalves, Suely Patrícia C., E-mail: suely.goncalves@lnnano.cnpem.br [Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), CEP 13083-970 Campinas, SP (Brazil); Strauss, Mathias; Delite, Fabrício S. [Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), CEP 13083-970 Campinas, SP (Brazil); Clemente, Zaira [Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), CEP 13083-970 Campinas, SP (Brazil); Laboratory of Ecotoxicology and Biosafety, Embrapa, CEP 13820-000 Jaguariúna, SP (Brazil); Castro, Vera L. [Laboratory of Ecotoxicology and Biosafety, Embrapa, CEP 13820-000 Jaguariúna, SP (Brazil); Martinez, Diego Stéfani T., E-mail: diego.martinez@lnnano.cnpem.br [Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), CEP 13083-970 Campinas, SP (Brazil); School of Technology, University of Campinas (UNICAMP), CEP 13484-332 Limeira, SP (Brazil)

    2016-09-15

    Activated carbon from pyrolysed sugarcane bagasse (ACPB) presented pore size ranges from 1.0 to 3.5 nm, and surface area between 1200 and 1400 m{sup 2} g{sup −1} that is higher than commonly observed to commercial activated carbon. The ACPB material was successfully loaded with of silver nanoparticles with diameter around 35 nm (0.81 wt.%). X-ray photoelectron spectroscopy (XPS) analyses showed that the material surface contains metallic/Ag{sup 0} (93.60 wt.%) and ionic/Ag{sup +} states (6.40 wt.%). The adsorption capacity of organic model molecules (i.e. methylene blue and phenol) was very efficient to ACPB and ACPB loaded with silver nanoparticles (ACPB-AgNP), indicating that the material modification with silver nanoparticles has not altered its adsorption capacity. ACPB-AgNP inhibited bacteria growth (Escherichia coli), it is a promising advantage for the use of these materials in wastewater treatment and water purification processes. However, ACPB-AgNP showed environmental risks, with toxic effect to the aquatic organism Hydra attenuata (i.e. LC50 value of 1.94 mg L{sup −1}), and it suppressed root development of Lycopersicum esculentum plant (tomato). Finally, this work draw attention for the environmental implications of activated carbon materials modified with silver nanoparticles. - Highlights: • Production of very efficient activated carbon by pyrolysis process of sugarcane bagasse. • Modification of activated carbon with silver nanoparticles to environmental remediation and water purification. • Activated carbon modified with silver nanoparticles showed acute ecotoxic effects.

  7. Activated carbon from pyrolysed sugarcane bagasse: Silver nanoparticle modification and ecotoxicity assessment

    International Nuclear Information System (INIS)

    Gonçalves, Suely Patrícia C.; Strauss, Mathias; Delite, Fabrício S.; Clemente, Zaira; Castro, Vera L.; Martinez, Diego Stéfani T.

    2016-01-01

    Activated carbon from pyrolysed sugarcane bagasse (ACPB) presented pore size ranges from 1.0 to 3.5 nm, and surface area between 1200 and 1400 m"2 g"−"1 that is higher than commonly observed to commercial activated carbon. The ACPB material was successfully loaded with of silver nanoparticles with diameter around 35 nm (0.81 wt.%). X-ray photoelectron spectroscopy (XPS) analyses showed that the material surface contains metallic/Ag"0 (93.60 wt.%) and ionic/Ag"+ states (6.40 wt.%). The adsorption capacity of organic model molecules (i.e. methylene blue and phenol) was very efficient to ACPB and ACPB loaded with silver nanoparticles (ACPB-AgNP), indicating that the material modification with silver nanoparticles has not altered its adsorption capacity. ACPB-AgNP inhibited bacteria growth (Escherichia coli), it is a promising advantage for the use of these materials in wastewater treatment and water purification processes. However, ACPB-AgNP showed environmental risks, with toxic effect to the aquatic organism Hydra attenuata (i.e. LC50 value of 1.94 mg L"−"1), and it suppressed root development of Lycopersicum esculentum plant (tomato). Finally, this work draw attention for the environmental implications of activated carbon materials modified with silver nanoparticles. - Highlights: • Production of very efficient activated carbon by pyrolysis process of sugarcane bagasse. • Modification of activated carbon with silver nanoparticles to environmental remediation and water purification. • Activated carbon modified with silver nanoparticles showed acute ecotoxic effects.

  8. Sorption of Np(V) by synthetic hydroxyapatite

    International Nuclear Information System (INIS)

    Moore, R.C.; Holt, K.; Zhao, H.; Hasan, A.; Awwad, N.; Gasser, M.; Sanchez, C.

    2003-01-01

    The sorption of Np(V) to synthetic hydroxyapatite was determined in batch experiments in a 0.1 M NaClO 4 solution. The hydroxyapatite used was of high purity as determined by SEM, EDS, XRD, FT-IR and ICP-MS analysis. Results from kinetic experiments with an initial Np(V) concentration of 1 x 10 -7 to 1 x 10 -6 M indicate the sorption process is relatively fast with more than 90% of the Np(V) being sorbed in approximately 3 hours. Equilibrium experiments performed over the pH range of 6 to 11 indicated sorption is strongly pH dependent with distribution coefficients, K d values (mL/g), increasing from 123 L/mole at pH 6 to 69 200 L/mole at pH 8.5. K d values are observed to decrease as pH further increases. Data points over a range of Np(V) concentrations were collected at pH 8 and fitted to the Langmuir isotherm model for simple adsorption. The Langmuir equation gave an excellent representation of the data. Langmuir parameters were determined to be C a = 0.032 mole/mole and K = 1.22 x 10 6 L/mole, indicating the high affinity of hydroxyapatite for Np(V) adsorption. (orig.)

  9. An overview on polynomial approximation of NP-hard problems

    Directory of Open Access Journals (Sweden)

    Paschos Vangelis Th.

    2009-01-01

    Full Text Available The fact that polynomial time algorithm is very unlikely to be devised for an optimal solving of the NP-hard problems strongly motivates both the researchers and the practitioners to try to solve such problems heuristically, by making a trade-off between computational time and solution's quality. In other words, heuristic computation consists of trying to find not the best solution but one solution which is 'close to' the optimal one in reasonable time. Among the classes of heuristic methods for NP-hard problems, the polynomial approximation algorithms aim at solving a given NP-hard problem in poly-nomial time by computing feasible solutions that are, under some predefined criterion, as near to the optimal ones as possible. The polynomial approximation theory deals with the study of such algorithms. This survey first presents and analyzes time approximation algorithms for some classical examples of NP-hard problems. Secondly, it shows how classical notions and tools of complexity theory, such as polynomial reductions, can be matched with polynomial approximation in order to devise structural results for NP-hard optimization problems. Finally, it presents a quick description of what is commonly called inapproximability results. Such results provide limits on the approximability of the problems tackled.

  10. The similar neurotoxic effects of nanoparticulate and ionic silver in vivo and in vitro

    DEFF Research Database (Denmark)

    Hadrup, Niels; Loeschner, Katrin; Mortensen, Alicja

    2012-01-01

    We compared the neurotoxic effects of 14nm silver nanoparticles (AgNPs) and ionic silver, in the form of silver acetate (AgAc), in vivo and in vitro. In female rats, we found that AgNPs (4.5 and 9mg AgNP/kg bw/day) and ionic silver (9mg Ag/kg bw/day) increased the dopamine concentration...... in the brain following 28 days of oral administration. The concentration of 5-hydroxytryptamine (5-HT) in the brain was increased only by AgNP at a dose of 9mg Ag/kg bw/day. Only AgAc (9mg Ag/kg bw/day) was found to increase noradrenaline concentration in the brain. In contrast to the results obtained from...... a 28-day exposure, the dopamine concentration in the brain was decreased by AgNPs (2.25 and 4.5mg/kg bw/day) following a 14-day exposure. These data suggest that there are differential effects of silver on dopamine depending on the length of exposure. In vitro, AgNPs, AgAc and a 12kDa filtered sub...

  11. Silver Nanoparticles Formed in a Colloidal System and a Polymer Matrix

    Science.gov (United States)

    Potapov, A. L.; Agabekov, V. E.; Belyi, V. N.

    2018-05-01

    The growth kinetics and particle-size distribution of Ag particles in a polyvinyl alcohol (PVA) composite, PVA film, and aqueous sol were studied using UV and visible spectroscopy, atomic force microscopy, and dynamic light scattering. A hypsochromic shift (55 nm) of the Ag nanoparticle (NP) surface plasmon absorption maximum was measured on going from the PVA composite to the film. The kinetics of Ag NP formation and their sizes were shown to depend considerably on UV irradiation, ultrasound action, and PVA concentration. It was established that UV irradiation accelerated Ag NP formation in the presence of reductants and destroyed the resulting NPs with a deficit of reductant. Partial destruction of the Ag NPs occurred under the influence of ultrasound whereas ultrasound action after UV irradiation reduced Ag+ on the clusters.

  12. Antioxidant and hepatoprotective role of selenium against silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Ansar S

    2017-10-01

    Full Text Available Sabah Ansar,1 Saad M Alshehri,2 Manal Abudawood,1 Sherifa S Hamed,3,4 Tansir Ahamad2 1Clinical Laboratory Sciences, Applied Medical Science, King Saud University, Riyadh, Saudi Arabia; 2Department of Chemistry, College of Science, King Saud University, Riyadh, Saudi Arabia; 3Zoology Department, College of Science, King Saud University, Riyadh, Saudi Arabia; 4Zoology Department, Faculty of Science, University of Alexandria, Moharram Bey, Alexandria, Egypt Abstract: Silver nanoparticles (AgNPs have attracted the most interest in terms of their potential biomedical and industrial applications. However, these nanoparticles have shown their toxic behavior toward environment, living tissues, and organisms. Selenium (Se, an essential trace element, is necessary for various metabolic processes, including protection against ­oxidative stress and immune function. The present study was undertaken to evaluate the effect of Se against AgNP-induced hepatic oxidative stress. AgNPs were synthesized and then prepared nanoparticles were characterized using various analytical techniques such as UV-visible spectroscopy, X-ray diffraction, and transmission electron microscopy. Rats were administered AgNPs intraperitoneally (5 mg/kg/day and Se (0.2 mg/kg was given by gavage. AgNP administration induced hepatic damage as indicated by the serum marker enzymes with reduction in levels of glutathione, and decrease in activities of SOD, CAT, and GSH-peroxidase (P<0.05. Decrease in levels of total antioxidant capacity (TAC and increase in level of C-reactive protein (CRP was also observed in AgNP-treated group compared to control group. However, Se markedly attenuated AgNP-induced biochemical alterations, levels of TAC, CRP, and serum transaminases (AST, ALT (P<0.05. Taken together, these findings suggest that administration of AgNPs produces hepatotoxicity in rats, whereas Se supplementation attenuates these effects. Keywords: silver nanoparticles, selenium, antioxidant

  13. Characterisation of bioaccumulation dynamics of three differently coated silver nanoparticles and aqueous silver in a simple freshwater food chain

    DEFF Research Database (Denmark)

    Kalman, Judit; Paul, Kai B.; Khan, Farhan R.

    2015-01-01

    This study investigated the bioaccumulation dynamics of silver nanoparticles (Ag NPs) with different coatings (polyvinyl pyrrolidone, polyethylene glycol and citrate), in comparison with aqueous Ag (added as AgNO3), in a simplified freshwater food chain comprising the green alga Chlorella vulgaris...... and the crustacean Daphnia magna. Algal uptake rate constants (ku) and membrane transport characteristics (binding site density, transporter affinity and strength of binding) were determined after exposing algae to a range of either aqueous Ag or Ag NP concentrations. In general, higher ku values were related......). Ag NPs were only visualised in algal cells exposed to high Ag NP concentrations. To establish D. magna biodynamic model constants, organisms were fed Ag-contaminated algae and depurated for 96 h. Assimilation efficiencies ranged from 10 to 25 % and the elimination of accumulated Ag followed a two...

  14. Sol-gel method for encapsulating molecules

    Science.gov (United States)

    Brinker, C. Jeffrey; Ashley, Carol S.; Bhatia, Rimple; Singh, Anup K.

    2002-01-01

    A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.

  15. Strong plasmonic enhancement of single molecule photostability in silver dimer optical antennas

    Directory of Open Access Journals (Sweden)

    Kaminska Izabela

    2018-02-01

    Full Text Available Photobleaching is an effect terminating the photon output of fluorophores, limiting the duration of fluorescence-based experiments. Plasmonic nanoparticles (NPs can increase the overall fluorophore photostability through an enhancement of the radiative rate. In this work, we use the DNA origami technique to arrange a single fluorophore in the 12-nm gap of a silver NP dimer and study the number of emitted photons at the single molecule level. Our findings yielded a 30× enhancement in the average number of photons emitted before photobleaching. Numerical simulations are employed to rationalize our results. They reveal the effect of silver oxidation on decreasing the radiative rate enhancement.

  16. Np(V) carbonates in solid state and aqueous solution

    International Nuclear Information System (INIS)

    Meinrath, G.

    1994-01-01

    The solubility of NaNpO 2 CO 3 (s) in 0.1M perchlorate solution at 25 deg C in equilibrium with 1.0% CO 2 /N 2 atmosphere has been investigated as a function of pH/lg [CO 3 2- ]. The solid phase was found hexagonal with a=1008.1±0.3 pm and c=991.1±0.2 pm. A solubility product of lg Ksp(NaNpO 2 CO 3 ) = -10.22±0.02 and a formation constant of the first Np(V) carbonato species of lg β 01 = 4.52±0.02 was evaluated. For the dicarbonato species an upper limit of lg lg β 02 2 partial pressure gave evidence that carbonato species are prevailing in solutions at both 1% and 0.03% CO 2 partial pressures. (author) 26 refs.; 4 figs.; 3 tabs

  17. Biokinetics of 237Np in mussels and shrimp

    International Nuclear Information System (INIS)

    Guary, J.C.; Fowler, S.W.

    1977-01-01

    Neptunium-237 kinetics were studied in marine shrimp and mussels using a thick source alpha counting technique. Bioaccumulation of 237 Np from water was relatively slow in both species, reaching whole body concentration factors of only 15 to 20 after three months. Surface adsorption was implicated in the initial uptake. Both uptake and loss of the radioisotope were not significantly affected by temperature; this may be a reflection of the physical nature of the uptake. By virtue of the large amounts of accumulated 237 Np associated with the exoskeleton of shrimp, molting will play an important role in the biogeochemical cycling of this transuranic in the marine environment. Rapid growth of organisms like mussels acts to reduce the 237 Np concentration in tissues during a period of decontamination

  18. New and superior adrenal scanning agent, NP-59

    International Nuclear Information System (INIS)

    Sarkar, S.D.; Beierwaltes, W.H.; Ice, R.D.; Basmadjian, G.P.; Hertzel, K.R.; Kennedy, W.P.; Mason, M.M.

    1975-01-01

    The first synthesis of 131 I-19-iodocholesterol had a 10 to 25 percent radiochemical impurity that was not iodide ion. This impurity has been identified as 6β- 131 I-iodomethyl-19-nor cholest-5(10)-en-3β-ol (NP-59) and has been synthesized. Tissue distribution studies with 131 I-NP-59 in rats and dogs revealed a higher adrenal uptake and adrenal-to-tissue ratios compared to 131 I 19-iodocholesterol, probably less in vivo deiodination, and superior adrenal images. A high uptake was seen in the adrenal medulla in addition to that in the cortex. Iodine-131-NP-59 is being evaluated for the early detection of adrenal--cortical disorders and as a potential scanning agent for detecting structural abnormalities of the adrenal medulla

  19. Garvey-Kelson mass relations and n-p interaction

    International Nuclear Information System (INIS)

    Gao Zaochun; Meng Jie; Chen Yongshou

    2001-01-01

    Two Garvey-Kelson mass relations are found to be directly related to the n-p interaction. In the case of the same nuclear core, the neutron-proton interaction energy between two neutrons and one proton ε 2n-1p is experimentally found to be close to that between one neutron and two protons ε 1n-2p , which is equivalent to the first Garvey-Kelson mass relation. The sum of ε 2n-1p and ε 1n-2p is close to the n-p interaction energy between two neutrons and two protons ε 2n-2p , which leads to the second Garvey-Kelson mass relation. An explanation of these two n-p interaction relations is presented. It is shown that both of these mass relations hold more accurately when the core is an even-even core

  20. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO3) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils

    International Nuclear Information System (INIS)

    Diez-Ortiz, Maria; Lahive, Elma; George, Suzanne; Ter Schure, Anneke; Van Gestel, Cornelis A.M.; Jurkschat, Kerstin; Svendsen, Claus; Spurgeon, David J.

    2015-01-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed. For the Ag NP, toxicity increased with time apparently driven by Ag ion dissolution from the added Ag NPs. Internal Ag in the earthworms did not always explain toxicity and suggested the presence of an internalised, low-toxicity Ag fraction (as intact or transformed NPs) after shorter aging times. Our results indicate that short-term exposures, without long-term soil aging, are not able to properly assess the environmental risk of Ag NPs and that ultimately, with aging time, Ag ion and Ag NP effect will merge to a common value. - Highlights: • Toxicity of silver nanoparticles in soils increased with time. • Standard tests do not adequately assess toxicity of silver NPs to earthworms. • Internal Ag in earthworms did not always explain toxicity after shorter aging times. • With aging time, Ag ion and Ag NP effect in soils will merge to a common value. - Toxicity of silver nanoparticles in soils increased with time with the result that commonly applied tests of 28 days exposure with freshly spiked soils do not adequately assess the environmental hazard of silver nanoparticles

  1. NMR studies of the dynamics of high-spin nitrophorins: comparative studies of NP4 and NP2 at close to physiological pH.

    Science.gov (United States)

    Berry, Robert E; Muthu, Dhanasekaran; Yang, Fei; Walker, F Ann

    2015-01-20

    The β-barrel nitrophorin (NP) heme proteins are found in the saliva of the blood-sucking insect Rhodnius prolixus, which synthesizes and stores nitric oxide (NO) in the salivary glands. NO is bound to iron of the NPs and is released by dilution and an increase in pH when the insect spits its saliva into the tissues of a victim, to aid in obtaining a blood meal. In the adult insect, there are four nitrophorins, NP1-NP4, which have sequence similarities in two pairs, NP1 and NP4 (90% identical) and NP2 and NP3 (80% identical). The available crystal structures of NP4 have been used to propose that pH-dependent changes in the conformation of two loops between adjacent β-strands at the front opening of the protein, the A-B and G-H loops, determine the rate of NO release. At pH 7.3, NP4 releases NO 17 times faster than NP2 does. In this work, the aqua complexes of NP4 and NP2 have been investigated by nuclear magnetic resonance (NMR) relaxation measurements to probe the pico- to nanosecond and micro- to millisecond time scale motions at two pH values, 6.5 and 7.3. It is found that NP4-OH2 is fairly rigid and only residues in the loop regions show dynamics at pH 6.5; at pH 7.3, much more dynamics of the loops and most of the β-strands are observed while the α-helices remain fairly rigid. In comparison, NP2-OH2 shows much less dynamics, albeit somewhat more than that of the previously reported NP2-NO complex [Muthu, D., Berry, R. E., Zhang, H., and Walker, F. A. (2013) Biochemistry 52, 7910-7925]. The reasons for this major difference between NP4 and NP2 are discussed.

  2. En-clave de Sol

    Directory of Open Access Journals (Sweden)

    Louis Manfield

    2011-12-01

    Full Text Available Ha pasado más de medio año desde que tuviera lugar el estallido reivindicativo del 16-M y las sucesivas explosiones en las que derivó este movimiento asambleario. Ninguno de los que asistieron a la manifestación del domingo, 15 de mayo, podía imaginarse que estaban pisando el centro de lo que iba a ser el escenario de la protesta colectiva más mediática de este país. Pero la Acampada ha sido algo más que el material de relleno para los medios de (desinformación y trend topic en redes sociales. Para los que nos dedicamos, en este caso, a la sociología, SOL se nos presenta como un juguete. Un sofisticado artefacto (su compleja y espesa red organizativa así lo atestiguan para poner a prueba, in situ y participando, la plasticidad y elasticidad social de la creatividad contestataria que ha convertido a un movimiento definido como indignado en un modelo autónomo de organización horizontal. Una cámara del tiempo donde el corto, el medio y largo plazo se entrecruzan con el corto, medio y largo alcance. Una ventana desde la que observar y anticipar el cambio que ya se está produciendo en el seno de la sociedad.

  3. Integrating nanohybrid membranes of reduced graphene oxide: chitosan: silica sol gel with fiber optic SPR for caffeine detection

    Science.gov (United States)

    Kant, Ravi; Tabassum, Rana; Gupta, Banshi D.

    2017-05-01

    Caffeine is the most popular psychoactive drug consumed in the world for improving alertness and enhancing wakefulness. However, caffeine consumption beyond limits can result in lot of physiological complications in human beings. In this work, we report a novel detection scheme for caffeine integrating nanohybrid membranes of reduced graphene oxide (rGO) in chitosan modified silica sol gel (rGO: chitosan: silica sol gel) with fiber optic surface plasmon resonance. The chemically synthesized nanohybrid membrane forming the sensing route has been dip coated over silver coated unclad central portion of an optical fiber. The sensor works on the mechanism of modification of dielectric function of sensing layer on exposure to analyte solution which is manifested in terms of red shift in resonance wavelength. The concentration of rGO in polymer network of chitosan and silica sol gel and dipping time of the silver coated probe in the solution of nanohybrid membrane have been optimized to extricate the supreme performance of the sensor. The optimized sensing probe possesses a reasonably good sensitivity and follows an exponentially declining trend within the entire investigating range of caffeine concentration. The sensor boasts of an unparalleled limit of detection value of 1.994 nM and works well in concentration range of 0-500 nM with a response time of 16 s. The impeccable sensor methodology adopted in this work combining fiber optic SPR with nanotechnology furnishes a novel perspective for caffeine determination in commercial foodstuffs and biological fluids.

  4. Dynamics of silver elution from functionalised antimicrobial nanofiltration membranes.

    Science.gov (United States)

    Choudhari, S; Habimana, O; Hannon, J; Allen, A; Cummins, E; Casey, E

    2017-07-01

    In an effort to mitigate biofouling on thin film composite membranes such as nanofiltration and reverse osmosis, a myriad of different surface modification strategies has been published. The use of silver nanoparticles (Ag-NPs) has emerged as being particularly promising. Nevertheless, the stability of these surface modifications is still poorly understood, particularly under permeate flux conditions. Leaching or elution of Ag-NPs from the membrane surface can not only affect the antimicrobial characteristics of the membrane, but could also potentially present an environmental liability when applied in industrial-scale systems. This study sought to investigate the dynamics of silver elution and the bactericidal effect of an Ag-NP functionalised NF270 membrane. Inductively coupled plasma-atomic emission spectroscopy was used to show that the bulk of leached silver occurred at the start of experimental runs, and was found to be independent of salt or permeate conditions used. Cumulative amounts of leached silver did, however, stabilise following the initial release, and were shown to have maintained the biocidal characteristics of the modified membrane, as observed by a higher fraction of structurally damaged Pseudomonas fluorescens cells. These results highlight the need to comprehensively assess the time-dependent nature of bactericidal membranes.

  5. High-field susceptibility in ferromagnetic NpOs2

    International Nuclear Information System (INIS)

    Dunlap, B.D.; Aldred, A.T.; Lam, D.J.; Davidson, G.R.

    1975-01-01

    NpOs 2 is known to be a ferromagnet with a Curie temperature of 7.5 0 K. Previous bulk magnetization measurements indicated a field-induced magnetization even well below the transition temperature. By a measurement of the local high-field susceptibility, using the Moessbauer effect in 237 Np, a susceptibility of (1.2 +- 0.2) x 10 -2 emu/mole at 1.6 0 K is obtained, in general agreement with the bulk measurement. Such a large susceptibility is best understood by a model f itinerant magnetism, although other properties of the material indicate localized behavior

  6. Adrenal scintiscanning with NP-59: a new radioiodinated cholesterol agent

    International Nuclear Information System (INIS)

    Miles, J.M.; Wahner, H.W.; Carpenter, P.C.; Salassa, R.M.; Northcutt, R.C.

    1979-01-01

    Adrenal imaging in the past has been limited in its clinical application by the long interval between administration of dose and visualization of adrenal glands. We review our experience with the use of a newer labeling agent, NP-59, in 29 patients with various adrenal disorders and in 4 normal subjects. With this agent, identification of adrenal lesions is possible with a high degree of accuracy, and diagnostic information is usually available within 48 hrs. NP-59 is particularly useful in evaluating primary aldosteronism and selected cases of Cushing's syndrome

  7. Biokinetics of 237Np in two marine benthic invertebrates

    International Nuclear Information System (INIS)

    Guary, J.C.; Fowler, S.W.

    1976-01-01

    The long-lived alpha-emitting actinide 237 Np (T 1/2 = 2.2 x 10 6 y) enters the aquatic environment directly from nuclear testing and reprocessing plant wastes as well as indirectly by in situ generation from 241 Am. Earlier studies on 239 Np in the Columbia river ecosystem demonstrated that neptunium accumulated in aquatic species such as algae, sponges and insect larvae but was not detectable in higher trophic level organisms. Based on these findings and the fact that neptunium is chemically similar to the rare earth elements, it has been suggested that this actinide would not easily become incorporated into aquatic biota

  8. Corrosion Compatibility Studies on Inconel-600 in NP Decontamination Solution

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang Yoon; Jung, Jun Young; Won, Huijun; Choi, Wangkyu; Moon, Jeikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    It is well known that corrosion and contamination process in the primary cooling circuit of nuclear reactors are essentially interrelated: the contaminant isotopes are mostly corrosion products activated in the reactor core, and the contamination takes place on the out-core of Inconel-600 surface. This radionuclide uptake takes place up to the inner oxide layer and oxide/metal interface. So, it is necessary to remove inner oxide layer as well as outer oxide layer for excellent decontamination effects. The outer oxide layers are composed of Fe{sub 3}O{sub 4} and NiFe{sub 2}O{sub 4}. On the other hand, the inner oxide layers are composed of Cr{sub 2}O{sub 3}, (Ni{sub 1-x}Ni{sub x})(Cr{sub 1-y}Fe{sub y}){sub 2}O{sub 4}, and FeCr{sub 2}O{sub 4}. Because of chromium in the trivalent oxidation state which is difficult to dissolve, the oxide layer has an excellent protectiveness and become hard to be decontaminated. Alkaline permanganate (AP) or nitric permanganate (NP) oxidative phase has been used to dissolve the chromium-rich oxide. A disadvantage of AP process is the generation of a large volume of secondary waste. On the other hand, that of NP process is the high corrosion rate for Ni-base alloys. Therefore, for the safe use of oxidative phase in PWR system decontamination, it is necessary to reformulate the NP chemicals for decrease of corrosion rate. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. To evaluate the general corrosion properties, weight change of NP treated specimens was measured. NP treated specimen surface was observed using optical microscope (OM) and scanning electron microscopy (SEM) for the evaluation of the localized corrosion. The effect of additives on the corrosion of the specimens was also evaluated. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications

  9. Corrosion Compatibility Studies on Inconel-600 in NP Decontamination Solution

    International Nuclear Information System (INIS)

    Park, Sang Yoon; Jung, Jun Young; Won, Huijun; Choi, Wangkyu; Moon, Jeikwon

    2013-01-01

    It is well known that corrosion and contamination process in the primary cooling circuit of nuclear reactors are essentially interrelated: the contaminant isotopes are mostly corrosion products activated in the reactor core, and the contamination takes place on the out-core of Inconel-600 surface. This radionuclide uptake takes place up to the inner oxide layer and oxide/metal interface. So, it is necessary to remove inner oxide layer as well as outer oxide layer for excellent decontamination effects. The outer oxide layers are composed of Fe 3 O 4 and NiFe 2 O 4 . On the other hand, the inner oxide layers are composed of Cr 2 O 3 , (Ni 1-x Ni x )(Cr 1-y Fe y ) 2 O 4 , and FeCr 2 O 4 . Because of chromium in the trivalent oxidation state which is difficult to dissolve, the oxide layer has an excellent protectiveness and become hard to be decontaminated. Alkaline permanganate (AP) or nitric permanganate (NP) oxidative phase has been used to dissolve the chromium-rich oxide. A disadvantage of AP process is the generation of a large volume of secondary waste. On the other hand, that of NP process is the high corrosion rate for Ni-base alloys. Therefore, for the safe use of oxidative phase in PWR system decontamination, it is necessary to reformulate the NP chemicals for decrease of corrosion rate. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. To evaluate the general corrosion properties, weight change of NP treated specimens was measured. NP treated specimen surface was observed using optical microscope (OM) and scanning electron microscopy (SEM) for the evaluation of the localized corrosion. The effect of additives on the corrosion of the specimens was also evaluated. This study describes the corrosion compatibility on Inconel-600 and type 304 stainless steel in NP decontamination solution for PWR applications. It is revealed that Inconel-600 specimen is more

  10. Modified Au nanoparticles-imprinted sol-gel, multiwall carbon nanotubes pencil graphite electrode used as a sensor for ranitidine determination.

    Science.gov (United States)

    Rezaei, B; Lotfi-Forushani, H; Ensafi, A A

    2014-04-01

    A new, simple, and disposable molecularly imprinted electrochemical sensor for the determination of ranitidine was developed on pencil graphite electrode (PGE) via cyclic voltammetry (CV). The PGEs were coated with MWCNTs containing the carboxylic functional group (f-MWCNTs), imprinted with sol-gel and Au nanoparticle (AuNPs) layers (AuNP/MIP-sol-gel/f-MWCNT/PGE), respectively, to enhance the electrode's electrical transmission and sensitivity. The thin film of molecularly imprinted sol-gel polymers with specific binding sites for ranitidine was cast on modified PGE by electrochemical deposition. The AuNP/MIP-sol-gel/f-MWCNT/PGE thus developed was characterized by electrochemical impedance spectroscopy (EIS) and CV. The interaction between the imprinted sensor and the target molecule was also observed on the electrode by measuring the current response of 5.0mMK3[Fe(CN)6] solution as an electrochemical probe. The pick currents of ranitidine increased linearly with concentration in the ranges of 0.05 to 2.0μM, with a detection limit of (S/N=3) 0.02μM. Finally, the modified electrode was successfully employed to determine ranitidine in human urine samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Comment on "A re-assessment of the safety of silver in household water treatment: rapid systematic review of mammalian in vivo genotoxicity studies".

    Science.gov (United States)

    Lantagne, Daniele; Rayner, Justine; Mittelman, Anjuliee; Pennell, Kurt

    2017-11-13

    We wish to thank Fewtrell, Majuru, and Hunter for their article highlighting genotoxic risks associated with the use of particulate silver for primary drinking water treatment. The recent promotion of colloidal silver products for household water treatment in developing countries is problematic due to previously identified concerns regarding manufacturing quality and questionable advertising practices, as well as the low efficiency of silver nanoparticles to treat bacteria, viruses, and protozoa in source waters. However, in the conclusion statement of the manuscript, Fewtrell et al. state, "Before colloidal Ag or AgNP are used in filter matrices for drinking water treatment, consideration needs to be given to how much silver is likely to be released from the matrix during the life of the filter." Unfortunately, it appears Fewtrell et al. were unaware that studies of silver nanoparticle and silver ion elution from ceramic filters manufactured and used in developing countries have already been completed. These existing studies have found that: 1) silver ions, not silver nanoparticles, are eluted from ceramic filters treated with silver nanoparticles or silver nitrate; and, 2) silver ions have not been shown to be genotoxic. Thus, the existing recommendation of applying silver nanoparticles to ceramic filters to prevent biofilm formation within the filter and improve microbiological efficacy should still be adhered to, as there is no identified risk to people who drink water from ceramic filters treated with silver nanoparticles or silver nitrate. We note that efforts should continue to minimize exposure to silver nanoparticles (and silica) to employees in ceramic filter factories in collaboration with the organizations that provide technical assistance to ceramic filter factories.

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

    Science.gov (United States)

    Hauri, James F.; Niece, Brian K.

    2011-01-01

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

  13. Differential bioaccumulation patterns of nanosized and dissolved silver in a land snail Achatina fulica.

    Science.gov (United States)

    Chen, Yuanzhen; Si, Youbin; Zhou, Dongmei; Dang, Fei

    2017-03-01

    With the increasing application in antimicrobial products, silver nanoparticles (AgNP) are inevitably released into the terrestrial environment, and pose potential risks to invertebrates such as land snails Achatina fulica, which take up AgNP from food and water. Here we differentiate Ag uptake biodynamic between Ag forms (i.e., PVP-AgNP vs. AgNO 3 ) and between exposure pathways. Snails assimilated Ag efficiently from lettuce leaves pre-exposed to AgNP, with assimilation efficiencies (AEs) averaging 62-85% and food ingestion rates of 0.11 ± 0.03 g g -1  d -1 . Dietary Ag bioavailability was independent on Ag forms, as revealed by comparable AEs between AgNP and AgNO 3 . However, the uptake rate constant from water was much lower for AgNP relative to AgNO 3 (2 × 10 -4 vs. 0.12 L g -1  d -1 ). The elimination rate constants were 0.0093 ± 0.0037 d -1 for AgNP and 0.019 ± 0.0077 d -1 for AgNO 3 . Biodynamic modeling further showed that dietary exposure was the dominant uptake pathway for AgNP in most circumstances, while for AgNO 3 the relative importance of waterborne and dietary exposure depended on Ag concentrations in food and water. Our findings highlight the importance of dietary uptake of AgNP during bioaccumulation, which should be considered in the risk assessment of these nanoparticles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Mesure de la vitesse d'infiltration des eaux dans le sol : Cas des sols ...

    African Journals Online (AJOL)

    C'est donc une infiltration superficielle qui ne peut pas modifier la composition des eaux de l'aquifère. Ces sols sont alors favorables à une telle agriculture. Mots clés: mesure, vitesse, infiltration, sols, pollutions, eau, Niari, Congo. English Title: Measuring the speed of the water infiltration into the soil: case of the soil of the ...

  15. Sorption of Np by UO2 under repository conditions

    Science.gov (United States)

    Kazakovskaya, T. V.; Zakharova, E. V.; Haire, M. J.

    2010-03-01

    This work is a part of the joint Russian - American Program on Beneficial Use of Depleted Uranium. The production of nuclear fuels results in the accumulation of large quantities of depleted uranium (DU) in the form of uranium hexafluoride (UF6), which is converted to uranium oxides. Depleted uranium dioxide (DUO2) can be used as a component of radiation shielding and as an absorbent for migrating radionuclides that may emerge from casks containing spent nuclear fuel (SNF) that are stored for hundreds of thousands of years in high-level wastes (HLW) and SNF repositories (e.g. Yucca Mountain Project). In this case DU oxides serve as an additional engineered chemical barrier. It is known that the primary radioisotope contributor to the calculated long-term radiation dose to the public at the Yucca Mountain SNF repository site boundary is neptunium-237 (237Np). This paper describes the sorption of 237Np in various media (deionized water and J-13 solution) by DUO2. Samples of DUO2 used in this work originated from the treatment of UF6 in a reducing media to form UO2(DUO2-1 at 600°C, DUO2-2 at 700°C, and DUO2-3 at 800°C). All species of DUO2 sorb Np(V) and Np(IV) from aqueous media. Equilibrium was achieved in 24 hours for Np(V) and in 2 hours for Np(IV). Np(V) sorption is accompanied with partial reduction of Np(V) to Np(IV) and vice versa. The sorption of Np(V) onto DUO2 surfaces is irreversible. The investigations on DUO2 transformations were performed under dynamic and static conditions. Under static conditions the solubility of the DUO2 samples in J-13 solution is considerably higher than in DW. When the pre-treatment temperature is decreased, the solubility of DUO2 samples raises regardless of the media. The experiments on interaction between DUO2 and aqueous media (DW and J-13 solution) under dynamic conditions demonstrated that during 30-40 days the penetration/filtration rate of DW and J-13 solution through a thin DUO2 layer decreased dramatically, and then

  16. The SOL width and the MHD interchange instability in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Kerner, W [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Pogutse, O [Kurchatov institute, Moscow (Russian Federation)

    1994-07-01

    Instabilities in the SOL plasma can strongly influence the SOL plasma behaviour and in particular the SOL width. The SOL stability analysis shows that there exists a critical ratio of the thermal energy and the magnetic energy. If the SOL beta is greater than this critical value, the magnetic field cannot prevent the plasma displacement and a strong MHD instability in the SOL occurs. In the opposite case only slower resistive instabilities can develop. A theoretical investigation of the SOL plasma stability is presented for JET single-null and double-null divertor configurations. The dependence of the stability threshold on the SOL beta and on the sheath resistance is established. Applying a simple mixing length argument gives the scaling of the SOL width. 5 refs., 2 figs.

  17. Solution Processed Silver Nanoparticles in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Marko Berginc

    2014-01-01

    Full Text Available A plasmonic effect of silver nanoparticles (Ag NPs in dye-sensitized solar cells (DSSCs is studied. The solutions of silver nitrate in isopropanol, ethylene glycol, or in TiO2 sol were examined as possible precursors for Ag NPs formation. The solutions were dip-coated on the top of the porous TiO2 layer. The results of optical measurements confirmed the formation of Ag NPs throughout the porous TiO2 layer after the heat treatment of the layers above 100°C. Heat treatment at 220°C was found to be optimal regarding the formation of the Ag NPs. The porous TiO2 layers with Ag NPs have been evaluated also in DSSC by measuring current-voltage characteristics and the external quantum efficiency of the cells. In addition, the amount of adsorbed dye has been determined to prove the plasmonic effect in the cells. The I-V characterization of the DSSCs revealed an increase of the short circuit current in the presence of Ag NPs although the amount of the attached dye molecules decreased. These results confirm that the performance enhancement is related to the plasmonic effect. However, neither a thin sol-gel TiO2 layer nor poly(4-vinylpyridine shells provide effective protection for the long term stability of the Ag NPs against the corrosion of I3-/I- based electrolyte.

  18. Simultaneous characterisation of silver nanoparticles and determination of dissolved silver in chicken meat subjected to in vitro human gastrointestinal digestion using single particle inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Ramos, K; Ramos, L; Gómez-Gómez, M M

    2017-04-15

    In this study, a chicken meat containing AgNPs (candidate reference material Nanolyse 14) has been used as a model matrix to study the fate and behaviour of AgNPs upon oral ingestion following an in vitro model that included saliva, gastric and intestinal digestions. The behaviour of a 40nm AgNPs standard solution during the three digestion steps was also evaluated. Sample preparation conditions were optimised to prevent AgNPs oxidation and/or aggregation and to ensure the representativeness of the reported results. Total silver released from the test sample and the evaluated AgNP standard was determined by inductively coupled plasma mass spectrometry (ICPMS). The presence of both AgNPs and dissolved silver in the extracts was confirmed by single particle (SP)-ICPMS analysis. AgNPs were sized and the particle number concentration determined in the three digestion juices. Experimental results demonstrated differentiated behaviours for AgNP from the standard solution and the meat sample highlighting the relevance of using physiological conditions for accurate risk assessment. In the most realistic scenario assayed (i.e., spiked chicken meat analysis), only 13% of the AgNPs present in the reference material would reach the intestine wall. Meanwhile, other bioaccessible dissolved forms of silver would account for as much as 44% of the silver initially spiked to the meat paste. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Immobilization of Trichoderma harzianum α-amylase on PPyAgNp/Fe3O4-nanocomposite: chemical and physical properties.

    Science.gov (United States)

    Mohamed, Saleh A; Al-Harbi, Majed H; Almulaiky, Yaaser Q; Ibrahim, Ibrahim H; Salah, Hala A; El-Badry, Mohamed O; Abdel-Aty, Azza M; Fahmy, Afaf S; El-Shishtawy, Reda M

    2018-03-26

    In this study, a new support has been developed by immobilization of α-amylase onto modified magnetic Fe 3 O 4 -nanoparticles. The characterization of soluble and immobilized α-amylases with regards to kinetic parameters, pH, thermal stability and reusability was studied. The effect of polypyrrole/silver nanocomposite (PPyAgNp) percentage on weight of Fe 3 O 4 and pH on the immobilization of α-amylase was studied. The highest immobilization efficiency (75%) was detected at 10% PPyAgNp/Fe 3 O 4 -nanocomposite and pH 7.0. Immobilization of α-amylase on PPyAgNp/Fe 3 O 4 -nanocomposite was characterized by FT-IR spectroscopy and scanning electron microscopy. The reusability of the immobilized enzyme activity was 80% of its initial activity after 10 reuses. The immobilized enzyme was more stable towards pH, temperature and metal ions compared with soluble enzyme. The kinetic study appeared higher affinity of immobilized enzyme (K m 2.5 mg starch) compared with soluble enzyme (K m 3.5 mg starch). In conclusion, the immobilization of α-amylase on PPyAgNp/Fe 3 O 4 -nanocomposite could successfully be used in industrial and medical applications.

  20. Mutagenicity of silver nanoparticles in CHO cells dependent on particle surface functionalization and metabolic activation

    Science.gov (United States)

    Guigas, Claudia; Walz, Elke; Gräf, Volker; Heller, Knut J.; Greiner, Ralf

    2017-06-01

    The potential of engineered nanomaterials to induce genotoxic effects is an important aspect of hazard identification. In this study, cytotoxicity and mutagenicity as a function of metabolic activation of three silver nanoparticle (AgNP) preparations differing in surface coating were determined in Chinese hamster ovary (CHO) subclone K1 cells. Three silver nanoparticle preparations ( x 90,0 culture medium containing 10% fetal calf serum (FCS) than in medium without FCS. The HPRT test without metabolic activation system S9 revealed that compared to the other AgNP formulations, citrate-coated Ag showed a lower genotoxic effect. However, addition of S9 increased the mutation frequency of all AgNPs and especially influenced the genotoxicity of Citrate-Ag. The results showed that exogenous metabolic activation of nanosilver is crucial even if interactions of the metabolic activation system, nanosilver, and cells are not really understood up to now.

  1. Citrate coated silver nanoparticles with modulatory effects on aflatoxin biosynthesis in Aspergillus parasiticus

    Science.gov (United States)

    Mitra, Chandrani

    The manufacture and usage of silver nanoparticles has drastically increased in recent years (Fabrega et al. 2011a). Hence, the levels of nanoparticles released into the environment through various routes have measurably increased and therefore are concern to the environment and to public health (Panyala, Pena-Mendez and Havel 2008). Previous studies have shown that silver nanoparticles are toxic to various organisms such as bacteria (Kim et al. 2007), fungi (Kim et al. 2008), aquatic plants (He, Dorantes-Aranda and Waite 2012a), arthropods (Khan et al. 2015), and mammalian cells (Asharani, Hande and Valiyaveettil 2009) etc. Most of the toxicity studies are carried out using higher concentrations or lethal doses of silver nanoparticles. However, there is no information available on how the fungal community reacts to the silver nanoparticles at nontoxic concentrations. In this study, we have investigated the effect of citrate coated silver nanoparticles (AgNp-cit) at a size of 20nm on Aspergillus parasiticus, a popular plant pathogen and well-studied model for secondary metabolism (natural product synthesis). A. parasiticus produces 4 major types of aflatoxins. Among other aflatoxins, aflatoxin B1 is considered to be one of most potent naturally occurring liver carcinogen, and is associated with an estimated 155,000 liver cancer cases globally (Liu and Wu 2010); therefore, contaminated food and feed are a significant risk factor for liver cancer in humans and animals (CAST 2003; Liu and Wu 2010). In this study, we have demonstrated the uptake of AgNp-cit (20nm) by A. parasiticus cells from the growth medium using a time course ICP-OES experiment. It was observed that the uptake of AgNp-cit had no effect on fungal growth and significantly decreased intracellular oxidative stress. It also down-regulated aflatoxin biosynthesis at the level of gene expression of aflatoxin pathway genes and the global regulatory genes of secondary metabolism. We also observed that the

  2. SOL-GEL SILICA-BASED Ag–Ca–P COATINGS WITH AGRESSIVE PRETREATMENT OF TITANIUM SUBSTRATE

    Directory of Open Access Journals (Sweden)

    ELENA BORSHCHEVA

    2011-12-01

    Full Text Available The aim of the experiment was the obtaining of thin silica coatings on titanium by sol-gel method, using mechanical (SiC - paper No.180 and chemical (leaching in HF pretreatments of the titanium substrates. The solutions were based on TEOS. For the sol-gel dipping process 4 different solutions were prepared: silica, silica with AgNO3 and silica + AgNO3 with brushite (CaHPO4·2H2O or monetite (CaHPO4 powders. The solutions were aged for 7 and 14 days at laboratory temperature. After sol-gel dip-coating process the samples were dried and fired. The adhesion of fired coatings was measured by tape test according to ASTM procedure and the bioactivity of the coatings was tested using in vitro test. The surfaces of the samples after firing, tape test and in vitro test were observed with the optical and electron microscopes. The firing results showed that silica-silver coatings did not change, brushite sol-gel coatings have cracked and the monetite sol-gel coatings have cracked also, but less than brushite ones. In spite of coating´s crackings, the square’s frames made on the surfaces were without any breakdowns after tape tests and the adhesion of all coatings was very good, classified by the highest grade 5. The results of in vitro tests showed that all coatings interacted with simulated body fluid (SBF. After exposition in SBF the new layer formed on substrates. In case of 7 days aged coatings containing brushite the new layer was uniform and compact. In case of 7 days aged coatings containing monetite the new layer was formed by crystals aggregated tightly together. The monetite and brushite coatings prepared from 14 days aged sol were the same as previous ones, but they were thicker. X-ray analyses after in vitro test confirmed dellaite, titanate and hydroxyapatite phases.

  3. Epistemologiese en ontologiese dominante in "Die beiteltjie" van NP ...

    African Journals Online (AJOL)

    Epistemologiese en ontologiese dominante in "Die beiteltjie" van N.P. van Wyk Louw en ... Log in or Register to get access to full text downloads. ... may be found in the shift of the dominant from problems of knowing to problems of modes of ...

  4. 2018 Status Report of NP04 (ProtoDUNE-SP)

    CERN Document Server

    Touramanis, C

    2018-01-01

    The NP04 Liquid Argon TPC has been constructed in the CERN Neutrino Facility and is in final preparation for taking beam data before the end of the current beam period at CERN. Progress in the last twelve months, current status, and plans are presented.

  5. Np Analysis in IAT-Samples Containing <10 Microgram Pu

    International Nuclear Information System (INIS)

    Ludwig, R.; Raab, W.; Dashdondog, J.; Balsley, S.

    2008-01-01

    A method for the determination of neptunium to plutonium in safeguards samples containing less than 10 microgram Pu is presented. The chemical treatment and the optimized measurement conditions for gamma spectrometry are reported. This method is based on thermal ionization mass spectrometry (TIMS) after chemical treatment and separation and was validated with mixtures of U, Pu and Np certified reference materials and using the 237 Np standard addition method, followed by separation of the waste fraction and gamma spectrometric analysis. The highest sensitivity, precision and accuracy in the determination of the Np:Pu ratio at microgram levels of Pu is achieved by evaluating 241 Pu and 233 Pa after measuring the adsorbent with a well-type gamma detector 3 weeks after chemical treatment. The repeatability of determining the Np:Pu ratio is estimated to be 5%, the maximum uncertainty as determined from comparing the 4 measurement modes is within ± 10% for samples containing 3 μg Pu, while being within ± 20% for 0.4 μg Pu. (authors)

  6. Np Analysis in IAT-Samples Containing <10 Microgram Pu

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, R.; Raab, W.; Dashdondog, J.; Balsley, S. [IAEA, Safeguards Analytical Laboratory, Wagramer Str. 5, P.O. Box 100, A-1400 Vienna (Austria)

    2008-07-01

    A method for the determination of neptunium to plutonium in safeguards samples containing less than 10 microgram Pu is presented. The chemical treatment and the optimized measurement conditions for gamma spectrometry are reported. This method is based on thermal ionization mass spectrometry (TIMS) after chemical treatment and separation and was validated with mixtures of U, Pu and Np certified reference materials and using the {sup 237}Np standard addition method, followed by separation of the waste fraction and gamma spectrometric analysis. The highest sensitivity, precision and accuracy in the determination of the Np:Pu ratio at microgram levels of Pu is achieved by evaluating {sup 241}Pu and {sup 233}Pa after measuring the adsorbent with a well-type gamma detector 3 weeks after chemical treatment. The repeatability of determining the Np:Pu ratio is estimated to be 5%, the maximum uncertainty as determined from comparing the 4 measurement modes is within {+-} 10% for samples containing 3 {mu}g Pu, while being within {+-} 20% for 0.4 {mu}g Pu. (authors)

  7. Two aspects of NP in top quark sector

    International Nuclear Information System (INIS)

    Drobnak, J.

    2014-01-01

    We present 2 different aspects of new physics (NP) in top quark sector. On one hand, we focus on the manifestation of NP in charged quark currents which affect the tW b vertex. Employing an effective theory approach to parametrize the NP of scales Λ well above the electro-weak, we show that in some cases the indirect B physics constraints are much more sever than the constraints coming from the helicity fraction measurements at Tevatron, which we analyse at next-to-leading order in QCD. On the other hand we show that the charge asymmetry in tt-bar production at the LHC, A C , and the forward-backward asymmetry at the Tevatron, A FB , are in general not tightly correlated. We demonstrate this by using an effective theory description as well as on-shell implementation in form of a light axigluon. The small value of A C measured at the LHC is thus shown not to exclude a NP interpretation of the anomalously large A FB at the Tevatron. (author)

  8. Breakdown of NpNn scheme in very heavy nuclei

    International Nuclear Information System (INIS)

    Varshney, A.K.; Singh, M.; Kumar, Rajesh; Gupta, K.K.; Gupta, D.K.

    2016-01-01

    The proton neutron interaction has been considered the key ingredient in the development of configuration mixing, collectivity and ultimately deformation in atomic nuclei for over five decades. Phenomenologically, the correlation of the integrated valance p - n interaction with the onset of collectivity and deformation has been described in terms of NpNn scheme

  9. Agreement of NP and VP Coordination in English and Korean

    Science.gov (United States)

    Hong, Sung-Ryong; Na, Won-Shik

    2011-01-01

    There have been long argumentations about this topic and people are still having difficulty in explaining precisely what the agreement values the mother NP phrase should have from two conjunct daughters which have different AGR (Agreement) values. Especially, this could be more complicated when the values of gender, number, and person of each…

  10. Mechanically stable antimicrobial chitosan-PVA-silver nanocomposite coatings deposited on titanium implants.

    Science.gov (United States)

    Mishra, Sandeep K; Ferreira, J M F; Kannan, S

    2015-05-05

    Bionanocomposite coatings with antimicrobial activity comprising polyvinyl alcohol (PVA)-capped silver nanoparticles embedded in chitosan (CS) matrix were developed by a green soft chemistry synthesis route. Colloidal sols of PVA-capped silver nanoparticles (AgNPs) were synthesized by microwave irradiating an aqueous solution comprising silver nitrate and PVA. The bionanocomposites were prepared by adding an aqueous solution of chitosan to the synthesized PVA-capped AgNPs sols in appropriate ratios. Uniform bionanocomposite coatings with different contents of PVA-capped AgNPs were deposited onto titanium substrates by "spread casting" followed by solvent evaporation. Nanoindentation and antimicrobial activity tests performed on CS and bionanocomposites revealed that the incorporation of PVA-capped AgNPs enhanced the overall functional properties of the coatings, namely their mechanical stability and bactericidal activity against Escherichia coli and Staphylococcus aureus. The coated specimens maintained their antimicrobial activity for 8h due to the slow sustained release of silver ions. The overall benefits for the relevant functional properties of the coatings were shown increase with increasing contents of PVA-capped AgNPs in the bionanocomposites. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Processing, characterization, and bactericidal activity of undoped and silver-doped vanadium oxides

    Energy Technology Data Exchange (ETDEWEB)

    Tousley, M.E.; Wren, A.W.; Towler, M.R. [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States); Mellott, N.P., E-mail: mellott@alfred.edu [Inamori School of Engineering, Alfred University, Alfred, NY 14803 (United States)

    2012-12-14

    Vanadium oxide (V) and silver-doped vanadium oxide (Ag-V) powders were prepared via sol-gel processing. Structural evolution and bactericidal activity was examined as a function of temperature ranging from 250, 350, 450 and 550 Degree-Sign C. Powders were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Raman spectroscopy. Results from all techniques showed vanadium pentoxide (V{sub 2}O{sub 5}) is the predominant phase regardless of heat treatment temperature or the addition of silver (Ag). XRD analysis suggests Ag is present as AgCl in samples heat treated to 250, 350, and 450 Degree-Sign C and as AgV{sub 6}O{sub 15} at 550 Degree-Sign C. Bactericidal activity was evaluated against Escherichia coli using the agar disk diffusion method considering both Ag-V and undoped, V powders. While the addition of Ag significantly increased bactericidal properties, the specific Ag valency, or crystal structure and morphology formed at higher temperatures, had little effect on functionality. -- Highlights: Black-Right-Pointing-Pointer Vanadium and silver-doped vanadium oxide powders were prepared via sol-gel. Black-Right-Pointing-Pointer Powders were characterized using advanced, complementary structural techniques. Black-Right-Pointing-Pointer Bactericidal activity was evaluated against E. coli. Black-Right-Pointing-Pointer Both vanadium and silver doped vanadium oxide show bactericidal activity.

  12. Structure, electrical characteristics, and high-temperature stability of aerosol jet printed silver nanoparticle films

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Md Taibur; McCloy, John; Panat, Rahul, E-mail: rahul.panat@wsu.edu, E-mail: rvchintalapalle@utep.edu [School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99163 (United States); Ramana, C. V., E-mail: rahul.panat@wsu.edu, E-mail: rvchintalapalle@utep.edu [Department of Mechanical Engineering, University of Texas at El Paso, El Paso, Texas 79968 (United States)

    2016-08-21

    Printed electronics has emerged as a versatile eco-friendly fabrication technique to create sintered nanoparticle (NP) films on arbitrary surfaces with an excellent control over the film microstructure. While applicability of such films for high-temperature applications is not explored previously, herein we report the high-temperature electrical stability of silver (Ag) metal NP films fabricated using an Aerosol Jet based printing technique and demonstrate that this behavior is dictated by changes in the film microstructure. In-situ high temperature (24–500 °C) impedance spectroscopy measurements show that the real part of the impedance increases with increasing temperature up to 150 °C, at which point a decreasing trend prevails until 300 °C, followed again by an increase in impedance. The electrical behavior is correlated with the in-situ grain growth of the Ag NP films, as observed afterwards by scanning electron microscopy and X-ray diffraction (XRD), and could be tailored by controlling the initial microstructure through sintering conditions. Using combined diffraction and spectroscopic analytical methods, it is demonstrated the Aerosol Jet printed Ag NP films exhibit enhanced thermal stability and oxidation resistance. In addition to establishing the conditions for stability of Ag NP films, the results provide a fundamental understanding of the effect of grain growth and reduction in grain boundary area on the electrical stability of sintered NP films.

  13. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions

    Science.gov (United States)

    Hsueh, Yi-Huang; Lin, Kuen-Song; Ke, Wan-Ju; Hsieh, Chien-Te; Chiang, Chao-Lung; Tzou, Dong-Ying; Liu, Shih-Tung

    2015-01-01

    The superior antimicrobial properties of silver nanoparticles (Ag NPs) are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI) staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10–50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation. PMID:26669836

  14. Structure, electrical characteristics, and high-temperature stability of aerosol jet printed silver nanoparticle films

    International Nuclear Information System (INIS)

    Rahman, Md Taibur; McCloy, John; Panat, Rahul; Ramana, C. V.

    2016-01-01

    Printed electronics has emerged as a versatile eco-friendly fabrication technique to create sintered nanoparticle (NP) films on arbitrary surfaces with an excellent control over the film microstructure. While applicability of such films for high-temperature applications is not explored previously, herein we report the high-temperature electrical stability of silver (Ag) metal NP films fabricated using an Aerosol Jet based printing technique and demonstrate that this behavior is dictated by changes in the film microstructure. In-situ high temperature (24–500 °C) impedance spectroscopy measurements show that the real part of the impedance increases with increasing temperature up to 150 °C, at which point a decreasing trend prevails until 300 °C, followed again by an increase in impedance. The electrical behavior is correlated with the in-situ grain growth of the Ag NP films, as observed afterwards by scanning electron microscopy and X-ray diffraction (XRD), and could be tailored by controlling the initial microstructure through sintering conditions. Using combined diffraction and spectroscopic analytical methods, it is demonstrated the Aerosol Jet printed Ag NP films exhibit enhanced thermal stability and oxidation resistance. In addition to establishing the conditions for stability of Ag NP films, the results provide a fundamental understanding of the effect of grain growth and reduction in grain boundary area on the electrical stability of sintered NP films.

  15. Structure, electrical characteristics, and high-temperature stability of aerosol jet printed silver nanoparticle films

    Science.gov (United States)

    Rahman, Md Taibur; McCloy, John; Ramana, C. V.; Panat, Rahul

    2016-08-01

    Printed electronics has emerged as a versatile eco-friendly fabrication technique to create sintered nanoparticle (NP) films on arbitrary surfaces with an excellent control over the film microstructure. While applicability of such films for high-temperature applications is not explored previously, herein we report the high-temperature electrical stability of silver (Ag) metal NP films fabricated using an Aerosol Jet based printing technique and demonstrate that this behavior is dictated by changes in the film microstructure. In-situ high temperature (24-500 °C) impedance spectroscopy measurements show that the real part of the impedance increases with increasing temperature up to 150 °C, at which point a decreasing trend prevails until 300 °C, followed again by an increase in impedance. The electrical behavior is correlated with the in-situ grain growth of the Ag NP films, as observed afterwards by scanning electron microscopy and X-ray diffraction (XRD), and could be tailored by controlling the initial microstructure through sintering conditions. Using combined diffraction and spectroscopic analytical methods, it is demonstrated the Aerosol Jet printed Ag NP films exhibit enhanced thermal stability and oxidation resistance. In addition to establishing the conditions for stability of Ag NP films, the results provide a fundamental understanding of the effect of grain growth and reduction in grain boundary area on the electrical stability of sintered NP films.

  16. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions.

    Directory of Open Access Journals (Sweden)

    Yi-Huang Hsueh

    Full Text Available The superior antimicrobial properties of silver nanoparticles (Ag NPs are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10-50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES and extended X-ray absorption fine structure (EXAFS analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation.

  17. Digging Movie from Phoenix's Sol 18

    Science.gov (United States)

    2008-01-01

    The Surface Stereo Imager on NASA's Phoenix Mars Lander recorded the images combined into this movie of the lander's Robotic Arm enlarging and combining the two trenches informally named 'Dodo' (left) and 'Goldilocks.' The 21 images in this sequence were taken over a period of about 2 hours during Phoenix's Sol 18 (June 13, 2008), or the 18th Martian day since landing. The main purpose of the Sol 18 dig was to dig deeper for learning the depth of a hard underlying layer. A bright layer, possibly ice, was increasingly exposed as the digging progressed. Further digging and scraping in the combined Dodo-Goldilocks trench was planned for subsequent sols. The combined trench is about 20 centimeters (about 8 inches) wide. The depth at the end of the Sol 18 digging is 5 to 6 centimeters (about 2 inches). The Goldilocks trench was the source of soil samples 'Baby Bear' and 'Mama Bear,' which were collected on earlier sols and delivered to instruments on the lander deck. The Dodo trench was originally dug for practice in collecting and depositing soil samples. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  18. Molecular size distribution of Np(V)-humate

    International Nuclear Information System (INIS)

    Sakamoto, Yoshiaki; Nagao, Seiya; Tanaka, Tadao

    1996-10-01

    Molecular size distributions of humic acid and Np(V)-humate were studied as a function of pH and an ionic strength by an ultrafiltration method. Small particle (10,000-30,000 daltons) of humic acid increased slightly with increases in solution pH. The ion strength dependence of the molecular size distribution was clearly observed for humic acid. The abundance ratio of humic acid in the range from 10,000 to 30,000 daltons increased with the ionic strength from 0.015 M to 0.105 M, in place of the decreasing of that in range from 30,000 to 100,000 daltons. Most of neptunium(V) in the 200 mg/l of the humic acid solution was fractionated into 10,000-30,000 daltons. The abundance ratio of neptunium(V) in the 10,000-30,000 daltons was not clearly dependent on pH and the ionic strength of the solution, in spite of the changing in the molecular size distribution of humic acid by the ionic strength. These results imply that the molecular size distribution of Np(V)-humate does not simply obey by that of the humic acid. Stability constant of Np(V)-humate was measured as a function of the molecular size of the humic acid. The stability constant of Np(V)-humate in the range from 10,000 to 30,000 daltons was highest value comparing with the constants in the molecular size ranges of 100,000 daltons-0.45μm, 30,000-100,000, 5,000-10,000 daltons and under 5,000 daltons. These results may indicate that the Np(V) complexation with humic acid is dominated by the interaction of neptunyl ion with the humic acid in the specific molecular size range. (author)

  19. Coiled-coil forming peptides for the induction of silver nanoparticles

    International Nuclear Information System (INIS)

    Božič Abram, Sabina; Aupič, Jana; Dražić, Goran; Gradišar, Helena; Jerala, Roman

    2016-01-01

    Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at around 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.

  20. Coiled-coil forming peptides for the induction of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Božič Abram, Sabina [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Graduate School of Biomedicine, University of Ljubljana, Ljubljana 1000 (Slovenia); Aupič, Jana [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Doctoral Programme in Chemical Sciences, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana 1000 (Slovenia); Dražić, Goran [Laboratory for Materials Chemistry, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); Gradišar, Helena [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); EN-FIST, Centre of Excellence, Trg Osvobodilne fronte 13, Ljubljana 1000 (Slovenia); Jerala, Roman, E-mail: roman.jerala@ki.si [Department of Synthetic Biology and Immunology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana (Slovenia); EN-FIST, Centre of Excellence, Trg Osvobodilne fronte 13, Ljubljana 1000 (Slovenia)

    2016-04-08

    Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at around 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.

  1. Application of Sol-Gel Method as a Protective Layer on a Specular Reflective Surface for Secondary Reflector in a Solar Receiver

    Energy Technology Data Exchange (ETDEWEB)

    Afrin, Samia; Dagdelen, John; Ma, Zhiwen; Kumar, Vinod

    2017-01-01

    Highly-specular reflective surfaces that can withstand elevated-temperatures are desirable for many applications including reflective heat shielding in solar receivers and secondary reflectors, which can be used between primary concentrators and heat collectors. A high-efficiency, high-temperature solar receiver design based on arrays of cavities needs a highly-specular reflective surface on its front section to help sunlight penetrate into the absorber tubes for effective flux spreading. Since this application is for high-temperature solar receivers, this surface needs to be durable and to maintain its optical properties through the usable life. Degradation mechanisms associated with elevated temperatures and thermal cycling, which include cracking, delamination, corrosion/oxidation, and environmental effects, could cause the optical properties of surfaces to degrade rapidly in these conditions. Protected mirror surfaces for these applications have been tested by depositing a thin layer of SiO2 on top of electrodeposited silver by means of the sol-gel method. To obtain an effective thin film structure, this sol-gel procedure has been investigated extensively by varying process parameters that affect film porosity and thickness. Endurance tests have been performed in a furnace at 150 degrees C for thousands of hours. This paper presents the sol-gel process for intermediate-temperature specular reflective coatings and provides the long-term reliability test results of sol-gel protected silver-coated surfaces.

  2. Effect of silver nanoparticles on the dielectric properties of holmium doped silica glass

    International Nuclear Information System (INIS)

    Rejikumar, P.R.; Jyothy, P.V.; Mathew, Siby; Thomas, Vinoy; Unnikrishnan, N.V.

    2010-01-01

    The effect of silver nanoparticle co-doping on the dielectric properties of holmium doped silica glasses was studied. Silver nanoparticles of size between 20 and 22 nm were produced by the sol-gel technique. One of the samples showed an icosahedral morphology of the nanocrystal formed, along with spherical morphology. It was found that the tuning of the dielectric constant values could be accomplished by co-doping. The sample, with 1 wt% of Ho, had low dielectric constant values within the range 100 Hz-3 MHz due to the formation of quasi-molecular structures of holmium. This effect was evaded to some extent with silver co-doping as a result of the interdispersion of holmium complexes. Also it was found that the co-doping produced a higher dielectric loss which was calculated from the tan δ-log f graph. The Cole-Cole parameters and the Jonscher power law parameters were also calculated and are presented.

  3. Controlled evaluation of silver nanoparticle dissolution using atomic force microscopy.

    Science.gov (United States)

    Kent, Ronald D; Vikesland, Peter J

    2012-07-03

    Incorporation of silver nanoparticles (AgNPs) into an increasing number of consumer products has led to concern over the potential ecological impacts of their unintended release to the environment. Dissolution is an important environmental transformation that affects the form and concentration of AgNPs in natural waters; however, studies on AgNP dissolution kinetics are complicated by nanoparticle aggregation. Herein, nanosphere lithography (NSL) was used to fabricate uniform arrays of AgNPs immobilized on glass substrates. Nanoparticle immobilization enabled controlled evaluation of AgNP dissolution in an air-saturated phosphate buffer (pH 7.0, 25 °C) under variable NaCl concentrations in the absence of aggregation. Atomic force microscopy (AFM) was used to monitor changes in particle morphology and dissolution. Over the first day of exposure to ≥10 mM NaCl, the in-plane AgNP shape changed from triangular to circular, the sidewalls steepened, the in-plane radius decreased by 5-11 nm, and the height increased by 6-12 nm. Subsequently, particle height and in-plane radius decreased at a constant rate over a 2-week period. Dissolution rates varied linearly from 0.4 to 2.2 nm/d over the 10-550 mM NaCl concentration range tested. NaCl-catalyzed dissolution of AgNPs may play an important role in AgNP fate in saline waters and biological media. This study demonstrates the utility of NSL and AFM for the direct investigation of unaggregated AgNP dissolution.

  4. Silver-Russell syndrome

    Directory of Open Access Journals (Sweden)

    Shohela Akhter

    2016-08-01

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

  5. Opportunity's Surroundings on Sol 1687 (Vertical)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008). Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction. Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast. This view is presented as a vertical projection with geometric seam correction.

  6. Opportunity's Surroundings on Sol 1687 (Polar)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008). Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction. Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast. This view is presented as a polar projection with geometric seam correction.

  7. Sol-gel synthesis of hydroxyapatite

    International Nuclear Information System (INIS)

    Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P.

    2010-01-01

    Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

  8. Asymmetric SOL Current in Vertically Displaced Plasma

    Science.gov (United States)

    Cabrera, J. D.; Navratil, G. A.; Hanson, J. M.

    2017-10-01

    Experiments at the DIII-D tokamak demonstrate a non-monotonic relationship between measured scrape-off layer (SOL) currents and vertical displacement event (VDE) rates with SOL currents becoming largely n=1 dominant as plasma is displaced by the plasma control system (PCS) at faster rates. The DIII-D PCS is used to displace the magnetic axis 10x slower than the intrinsic growth time of similar instabilities in lower single-null plasmas. Low order (n VDE instabilities observed when vertical control is disabled. Previous inquiry shows VDE asymmetry characterized by SOL current fraction and geometric parameters of tokamak plasmas. We note that, of plasmas displaced by the PCS, short displacement time scales near the limit of the PCS temporal control appear to result in larger n=1/n=2 asymmetries. Work supported under USDOE Cooperative Agreement DE-FC02-04ER54698 and DE-FG02-04ER54761.

  9. Upgrades for TwinSol facility

    Energy Technology Data Exchange (ETDEWEB)

    O’Malley, P.D.; Bardayan, D.W.; Kolata, J.J.; Hall, M.R.; Hall, O.; Allen, J. [Physics Department, University of Notre Dame, Notre Dame, IN 46556 (United States); Becchetti, F.D. [Physics Department, U. Michigan, Ann Arbor MI 48109 (United States)

    2016-06-01

    TwinSol, a pair of coupled, superconducting solenoids, was one of the first devices capable of producing beams of radioactive nuclei at energies near the Coulomb barrier. A primary beam from University of Notre Dame (UND) tandem accelerator is used to bombard a primary target producing a secondary beam in flight. TwinSol is used to gather, separate, and focus the recoils. Since it was commissioned at the UND in 1997, at least 58 publications have reported data from its use and there have been hundreds of collaborators from many different countries that use this device. Currently, plans are in place at the UND to provide several upgrades to TwinSol, including a multi-cell gas production target and the possible addition of a third solenoid. Upgrades currently in progress will be discussed along with future plans.

  10. NeptuniumV Retention by Siderite under Anoxic Conditions: Precipitation of NpO2-Like Nanoparticles and of NpIV Pentacarbonate.

    Science.gov (United States)

    Scheinost, Andreas C; Steudtner, Robin; Hübner, René; Weiss, Stephan; Bok, Frank

    2016-10-04

    The Np V retention by siderite, an Fe II carbonate mineral with relevance for the near-field of high-level radioactive waste repositories, was investigated under anoxic conditions. Batch sorption experiments show that siderite has a high affinity for aqueous Np V O 2 + across pH 7 to 13 as expressed by solid-water distribution coefficients, log R d, > 5, similar to the log R d determined for the (solely) tetravalent actinide Th on calcite, suggesting reduction of Np V to Np IV by siderite. Np L 3 -edge X-ray absorption near edge (XANES) spectroscopy conducted in a pH range typical for siderite-containing host rocks (7-8), confirmed the tetravalent Np oxidation state. Extended X-ray absorption fine-structure (EXAFS) spectroscopy revealed a local structure in line with NpO 2 -like nanoparticles with diameter nanoparticles (∼10 -9 M), along with their negligible surface charge at neutral pH conditions which favors particle aggregation, suggest an efficient retention of Np in the near-field of radioactive waste repositories. When Np V was added to ferrous carbonate solution, the subsequent precipitation of siderite did not lead to a structural incorporation of Np IV by siderite, but caused precipitation of a Np IV pentacarbonate phase.

  11. Green synthesis, characterization of gold and silver nanoparticles and their potential application for cancer therapeutics

    International Nuclear Information System (INIS)

    Patra, Sujata; Mukherjee, Sudip; Barui, Ayan Kumar; Ganguly, Anirban; Sreedhar, Bojja; Patra, Chitta Ranjan

    2015-01-01

    In the present article, we demonstrate the delivery of anti-cancer drug to the cancer cells using biosynthesized gold and silver nanoparticles (b-AuNP & b-AgNP). The nanoparticles synthesized by using Butea monosperma (BM) leaf extract are thoroughly characterized by various analytical techniques. Both b-AuNP and b-AgNP are stable in biological buffers and biocompatible towards normal endothelial cells (HUVEC, ECV-304) as well as cancer cell lines (B16F10, MCF-7, HNGC2 & A549). Administration of nanoparticle based drug delivery systems (DDSs) using doxorubicin (DOX) [b-Au-500-DOX and b-Ag-750-DOX] shows significant inhibition of cancer cell proliferation (B16F10, MCF-7) compared to pristine drug. Therefore, we strongly believe that biosynthesized nanoparticles will be useful for the development of cancer therapy using nanomedicine approach in near future. - Highlights: • Biosynthesis of gold and silver nanoparticles using plant leaf extract • The approach is clean, efficient, eco-friendly & economically safe. • Biosynthesized nanoparticles are biocompatible towards normal and cancer cells. • Design and development of biosynthesized nanoparticle based drug delivery systems • Biosynthesized nanoparticles could be useful for cancer and other diseases

  12. Green synthesis, characterization of gold and silver nanoparticles and their potential application for cancer therapeutics

    Energy Technology Data Exchange (ETDEWEB)

    Patra, Sujata; Mukherjee, Sudip; Barui, Ayan Kumar; Ganguly, Anirban [Biomaterials Group, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, Telangana State (India); Sreedhar, Bojja [Inorganic and Physical Chemistry Division, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, Telangana State (India); Patra, Chitta Ranjan, E-mail: crpatra@iict.res.in [Biomaterials Group, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, Telangana State (India)

    2015-08-01

    In the present article, we demonstrate the delivery of anti-cancer drug to the cancer cells using biosynthesized gold and silver nanoparticles (b-AuNP & b-AgNP). The nanoparticles synthesized by using Butea monosperma (BM) leaf extract are thoroughly characterized by various analytical techniques. Both b-AuNP and b-AgNP are stable in biological buffers and biocompatible towards normal endothelial cells (HUVEC, ECV-304) as well as cancer cell lines (B16F10, MCF-7, HNGC2 & A549). Administration of nanoparticle based drug delivery systems (DDSs) using doxorubicin (DOX) [b-Au-500-DOX and b-Ag-750-DOX] shows significant inhibition of cancer cell proliferation (B16F10, MCF-7) compared to pristine drug. Therefore, we strongly believe that biosynthesized nanoparticles will be useful for the development of cancer therapy using nanomedicine approach in near future. - Highlights: • Biosynthesis of gold and silver nanoparticles using plant leaf extract • The approach is clean, efficient, eco-friendly & economically safe. • Biosynthesized nanoparticles are biocompatible towards normal and cancer cells. • Design and development of biosynthesized nanoparticle based drug delivery systems • Biosynthesized nanoparticles could be useful for cancer and other diseases.

  13. Antibacterial Efficacy of Gold and Silver Nanoparticles Functionalized with the Ubiquicidin (29–41 Antimicrobial Peptide

    Directory of Open Access Journals (Sweden)

    Enrique Morales-Avila

    2017-01-01

    Full Text Available Recent studies have demonstrated that drug antimicrobial activity is enhanced when metallic nanoparticles are used as an inorganic support, obtaining synergic effects against microorganisms. The cationic antimicrobial peptide ubiquicidin 29–41 (UBI has demonstrated high affinity and sensitivity towards fungal and bacterial infections. The aim of this research was to prepare and evaluate the antimicrobial efficacy of engineered multivalent nanoparticle systems based on silver or gold nanoparticles functionalized with UBI. Spectroscopy techniques demonstrated that NPs were functionalized with UBI mainly through interactions with the -NH2 groups. A significant increase in the antibacterial activity against Escherichia coli and Pseudomonas aeruginosa was obtained with the conjugate AgNP-UBI with regard to that of AgNP. No inhibition of bacterial growth was observed with AuNP and AuNP-UBI using a nanoparticle concentration of up to 182 μg mL−1. Nonetheless, silver nanoparticles conjugated to the UBI antimicrobial peptide may provide an alternative therapy for topical infections.

  14. 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.

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

    Science.gov (United States)

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

    2018-02-01

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

  16. Opportunity's Surroundings on Sol 1818 (Vertical)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends. This view is presented as a vertical projection with geometric seam correction. North is at the top. The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view. The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

  17. Collisionality dependent transport in TCV SOL plasmas

    DEFF Research Database (Denmark)

    Garcia, Odd Erik; Pitts, R.A.; Horacek, J.

    2007-01-01

    Results are presented from probe measurements in the low field side scrape-off layer (SOL) region of TCV during plasma current scan experiments. It is shown that with decreasing plasma current the radial particle density profile becomes broader and the fluctuation levels and turbulence driven...... radial particle flux increase. In the far SOL the fluctuations exhibit a high degree of statistical similarity and the particle density and flux at the wall radius scale inversely with the plasma current. Together with previous TCV density scan experiments, this indicates that plasma fluctuations...

  18. Opportunity's Surroundings on Sol 1818 (Polar)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends. This view is presented as a polar projection with geometric seam correction. North is at the top. The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view. The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

  19. Spirit Beside 'Home Plate,' Sol 1809

    Science.gov (United States)

    2009-01-01

    NASA Mars Exploration Rover Spirit used its navigation camera to take the images assembled into this 120-degree view southward after a short drive during the 1,809th Martian day, or sol, of Spirit's mission on the surface of Mars (February 3, 2009). Spirit had driven about 2.6 meters (8.5 feet) that sol, continuing a clockwise route around a low plateau called 'Home Plate.' In this image, the rocks visible above the rovers' solar panels are on the slope at the northern edge of Home Plate. This view is presented as a cylindrical projection with geometric seam correction.

  20. Neutron detector using sol-gel absorber

    Science.gov (United States)

    Hiller, John M.; Wallace, Steven A.; Dai, Sheng

    1999-01-01

    An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.

  1. Electrochemistry of actinide on electrochemically reduced graphene oxide: Electrocatalysis of Np(VI)O22+/Np(V)O2+ in nitric acid solution

    International Nuclear Information System (INIS)

    Ambolikar, Arvind S.; Guin, Saurav K.; Kasar, U.M.; Kamat, J.V.

    2015-01-01

    Highlights: • First report of aqueous electrochemistry of neptunium on electrochemically reduced graphene oxide (ERGNO). • First report on the electrochemical impedance spectroscopy of Np (VI) O 2 2+ /Np (V) O 2 + . • The electrochemical reversibility of Np (VI) O 2 2+ /Np (V) O 2 + redox couple improves on ERGNO compared to GC. • ERGNO shows higher sensitivity for the determination of Np compared to bare GC electrode. • The efficiency of detection of Np by ERGNO is improved by virtue of the electrocatalysis. - Abstract: Driven by the academic interest, we have studied the aqueous electrochemistry of neptunium (Np) in 1 M nitric acid solution on the electrochemically reduced graphene oxide (ERGNO) modified glassy carbon (GC) electrode. Similar to our previous experiences on the electrocatalytic action of ERGNO on the electrochemistry of uranium(VI)/uranium(IV) and plutonium(IV)/plutonium(III) redox couples, the present study confirms the robust electrocatalytic ability of ERGNO for the redox reaction of Np (VI) O 2 2+ /Np (V) O 2 + in acidic solution even at high anodic working potentials. The extent of the electrochemical reversibility of Np (VI) O 2 2+ /Np (V) O 2 + redox couple increases on ERGNO compared to the bare GC electrode. For the first time, the electron transfer reaction of Np (VI) O 2 2+ /Np (V) O 2 + redox couple is investigated by electrochemical impedance spectroscopy. The improved sensitivity as well as the lower limit of detection of Np by anodic square wave voltammetry on ERGNO compared to bare GC opens up the application of ERGNO in the nuclear science and technology.

  2. Antifouling coating with controllable and sustained silver release for long-term inhibition of infection and encrustation in urinary catheters.

    Science.gov (United States)

    Wang, Rong; Neoh, Koon Gee; Kang, En-Tang; Tambyah, Paul Anantharajah; Chiong, Edmund

    2015-04-01

    Urinary tract infections constitute a large proportion of nosocomial infections, and the urinary catheter is the most important predisposing factor. Encrustation induced by urease-producing uropathogens like Proteus mirabilis causes further complications. In the present work, a strategy for controllable and sustained release of silver over several weeks has been developed for combating bacterial infection and encrustation in urinary devices. Silver nanoparticles (AgNPs) were first immobilized on polydopamine (PDA) pre-treated silicone catheter surface and this was followed by another PDA coating. The number of AgNP-PDA bilayers could be manipulated to control the amount of silver loaded and its subsequent release. Poly(sulfobetaine methacrylate-co-acrylamide) was then grafted to provide an antifouling outer layer, and to ensure free diffusion of Ag from the surface. The micron-scale combination of an antifouling coating with AgNP-PDA bilayers reduced colonization of the urinary catheter by uropathogens by approximately two orders of magnitude. With one and two AgNP-PDA bilayers, the coated catheter could resist encrustation for 12 and 45 days, respectively, compared with approximately 6 days with the Dover™ silver-coated catheter. Such anti-infective and anti-encrustation catheters can potentially have a large impact on reducing patient morbidity and healthcare expenditure. © 2014 Wiley Periodicals, Inc.

  3. Silver nanoparticle accumulation by aquatic organisms – neutron activation as a tool for the environmental fate of nanoparticles tracing

    Directory of Open Access Journals (Sweden)

    Asztemborska Monika

    2014-12-01

    Full Text Available Water environments are noted as being some of the most exposed to the influence of toxic nanoparticles (NPs. Therefore, there is a growing need for the investigation of the accumulation and toxicity of NPs to aquatic organisms. In our studies neutron activation followed by gamma spectrometry and liquid scintillation counting were used for studying the accumulation of silver nanoparticles (AgNPs by freshwater larvae of Chironomus and fish Danio rerio. The influence of exposition time, concentration and the source of nanoparticles on the efficiency of AgNP accumulation were studied. It was found that AgNPs are efficiently accumulated by Chironomid larvae for the first 30 hours of exposition; then, the amount of silver nanoparticles decreases. The silver content in larvae increases together with the NP concentration in water. Larvae which have accumulated AgNPs can be a source of nanoparticles for fish and certainly higher levels of Ag in the trophic chain. In comparison with water contamination, silver nanoparticles are more efficiently accumulated if fish are fed with AgNP-contaminated food. Finally, it was concluded that the applied study strategy, including neutron activation of nanoparticles, is very useful technique for tracing the uptake and accumulation of NPs in organisms

  4. Antibacterial and anti-adhesion effects of the silver nanoparticles-loaded poly(L-lactide) fibrous membrane

    International Nuclear Information System (INIS)

    Liu, Shen; Zhao, Jingwen; Ruan, Hongjiang; Wang, Wei; Wu, Tianyi; Cui, Wenguo; Fan, Cunyi

    2013-01-01

    The complications of tendon injury are frequently compromised by peritendinous adhesions and tendon sheath infection. Physical barriers for anti-adhesion may increase the incidence of postoperative infection. This study was designed to evaluate the potential of silver nanoparticles (AgNPs)-loaded poly(L-lactide) (PLLA) electrospun fibrous membranes to prevent adhesion formation and infection. Results of an in vitro drug release study showed that a burst release was followed by sustained release from electrospun fibrous membranes with a high initial silver content. Fewer fibroblasts adhered to and proliferated on the AgNP-loaded PLLA electrospun fibrous membranes compared with pure PLLA electrospun fibrous membrane. In the antibacterial test, the AgNP-loaded PLLA electrospun fibrous membranes can prevent the adhesion of Gram-positive Staphylococcus aureus and Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa. Taken together, these results demonstrate that AgNP-loaded PLLA electrospun fibrous membranes have the convenient practical medical potential of reduction of infection and adhesion formation after tendon injury. - Highlights: ► Silver nanoparticles are directly electrospun into PLLA fibrous membrane. ► Long-lasting release of Ag + ions is achieved. ► Cytotoxicity of silver ions benefits the anti-proliferation of physical barriers. ► Broad anti-microbial effect of drug-loaded fibrous membrane is revealed. ► Antibacterial and anti-adhesion effects of the physical barriers are combined

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-07-06

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

  7. 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.

  8. Assessment of the fate of silver nanoparticles in the A(2)O-MBR system.

    Science.gov (United States)

    Yuan, Zhi-Hua; Yang, Xiaoyong; Hu, Anyi; Zheng, Yu-Ming; Yu, Chang-Ping

    2016-02-15

    In this study, we employed a bench scale A(2)O-MBR (anaerobic-anoxic-oxic membrane bioreactor) system to systematically investigate the behavior and distribution of silver nanoparticles (AgNPs) in the activated sludge. The results showed that AgNPs would aggregate and form Ag-sulfur complexes in the activated sludge, and the dissolved silver only reached 13.6 μg/L when AgNPs of 5mg/L was spiked into the A(2)O-MBR. The long-term mass balance analysis showed that most of the silver contents were accumulated in the bioreactor and wasted excess sludge. Only a small fraction (less than 0.5%) of silver could get across the hollow fiber membranes with 0.1 μm nominal pore size in the effluent. In addition, the comparison between total AgNP concentration in aerobic sludge supernatant and effluent suggested that the membrane modules played a role in controlling the discharge of AgNPs into the effluent, especially under a higher influent concentration of AgNPs. Our results also showed that the adsorbed AgNPs or silver complexes in activated sludge still could release dissolved silver at the ambient pH. Thus, since activated sludge could be a sink for AgNPs, the risks of AgNPs in wasted excess sludge during utilization and disposal should be further studied. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Antibacterial hemostatic dressings with nanoporous bioglass containing silver

    Directory of Open Access Journals (Sweden)

    Hu G

    2012-05-01

    Full Text Available Gangfeng Hu,1 Luwei Xiao,2 Peijian Tong,2 Dawei Bi,1 Hui Wang,1 Haitao Ma,1 Gang Zhu,1 Hui Liu21The First People’s Hospital of Xiaoshan, Hangzhou, China; 2Zhejiang Traditional Chinese Medical University, Hangzhou, ChinaAbstract: Nanoporous bioglass containing silver (n-BGS was fabricated using the sol-gel method, with cetyltrimethyl ammonium bromide as template. The results showed that n-BGS with nanoporous structure had a surface area of 467 m2/g and a pore size of around 6 nm, and exhibited a significantly higher water absorption rate compared with BGS without nanopores. The n-BGS containing small amounts of silver (Ag had a slight effect on its surface area. The n-BGS containing 0.02 wt% Ag, without cytotoxicity, had a good antibacterial effect on Escherichia coli, and its antibacterial rate reached 99% in 12 hours. The n-BGS’s clotting ability significantly decreased prothrombin time (PT and activated partial thromboplastin time (APTT, indicating n-BGS with a higher surface area could significantly promote blood clotting (by decreasing clotting time compared with BGS without nanopores. Effective hemostasis was achieved in skin injury models, and bleeding time was reduced. It is suggested that n-BGS could be a good dressing, with antibacterial and hemostatic properties, which might shorten wound bleeding time and control hemorrhage.Keywords: antibacterial, bioglass, cytotoxicity, dressing, hemostasis, nanopore, silver

  10. Unique coexistence of dispersion stability and nanoparticle chemisorption in alkylamine/alkylacid encapsulated silver nanocolloids.

    Science.gov (United States)

    Aoshima, Keisuke; Hirakawa, Yuya; Togashi, Takanari; Kurihara, Masato; Arai, Shunto; Hasegawa, Tatsuo

    2018-04-17

    Surface encapsulation of metal nanoparticles (NPs) is fundamental to achieve sufficient dispersion stability of metal nanocolloids, or metal nanoink. However, the feature is incompatible with surface reactive nature of the metal NPs, although these features are both essential to realizing the functional applications into printed electronics technologies. Here we show that two different kinds of encapsulation for silver NPs (AgNPs) by alkylamine and alkylacid together are the key to achieve unique compatibility between the high dispersion stability as dense nanoclolloids and the AgNP chemisorption printing on activated patterned polymer surfaces. Advanced confocal dynamic light scattering study reveals that an additive trace amount of oleic acid is the critical parameter for controlling the dispersion and coagulative (or surface-reactive) characteristics of the silver nanocolloids. The composition of the disperse media is also important for obtaining highly concentrated but low-viscosity silver nanocolloids that show very stable dispersion. The results demonstrate that the high-resolution AgNP chemisorption printing is possible only by using unique silver nanocolloids composed of an exceptional balance of ligand formulation and dispersant composition.

  11. Silver nanoparticle–carbon nanotube hybrid films: Preparation and electrochemical sensing

    International Nuclear Information System (INIS)

    Yu Aimin; Wang, Qingxia; Yong, Jiawey; Mahon, Peter J.; Malherbe, Francois; Wang Feng; Zhang Haili; Wang, James

    2012-01-01

    Multi-walled carbon nanotube (MWCNT) multilayer thin films with controlled thickness were pre-assembled on electrodes by alternatively depositing MWCNT and poly(diallyldimethylammonium chloride) (PDDA) via a layer-by-layer self-assembly technique. Silver nanoparticles (Ag NPs) were then electro-deposited on the MWCNT surface from AgNO 3 solution using a potentiostatic double pulse technique. The size, density and morphology of silver nanoparticles that electrodeposited on MWCNT were controlled by the pulse parameters. When a voltage pulse of −600 mV was used to nucleate silver nanoparticles and a growth pulse of −105 mV was applied to grow the particles, silver particles of 10–500 nm with varied density could be electro-generated on MWCNT surface. The formation of Ag NPs and the morphology of the MWCNT/Ag NP composite films were characterized by scanning electron microscopy (SEM). The MWCNT/Ag NP composite films exhibited excellent electrocatalytic activity to the reduction of hydrogen peroxide which was also shown to be slightly affected by the size and density of Ag NPs on the film.

  12. Genomics-based screening of differentially expressed genes in the brains of mice exposed to silver nanoparticles via inhalation

    International Nuclear Information System (INIS)

    Lee, Hye-Young; Choi, You-Jin; Jung, Eun-Jung; Yin, Hu-Quan; Kwon, Jung-Taek; Kim, Ji-Eun; Im, Hwang-Tae; Cho, Myung-Haing; Kim, Ju-Han; Kim, Hyun-Young; Lee, Byung-Hoon

    2010-01-01

    Silver nanoparticles (AgNP) are among the fastest growing product categories in the nanotechnology industry. Despite the importance of AgNP in consumer products and clinical applications, relatively little is known regarding AgNP toxicity and its associated risks. We investigated the effects of AgNP on gene expression in the mouse brain using Affymetrix Mouse Genome Arrays. C57BL/6 mice were exposed to AgNP (geometric mean diameter, 22.18 ± 1.72 nm; 1.91 x 10 7 particles/cm 3 ) for 6 h/day, 5 days/week using the nose-only exposure system for 2 weeks. Total RNA isolated from the cerebrum and cerebellum was subjected to hybridization. From over 39,000 probe sets, 468 genes in the cerebrum and 952 genes in the cerebellum were identified as AgNP-responsive (one-way analysis of variance; p < 0.05). The largest groups of gene products affected by AgNP exposure included 73 genes in the cerebrum and 144 genes in the cerebellum. AgNP exposure modulated the expression of several genes associated with motor neuron disorders, neurodegenerative disease, and immune cell function, indicating potential neurotoxicity and immunotoxicity associated with AgNP exposure. Real-time PCR data for five genes analyzed from whole blood showed good correlation with the observed changes in the brain. Following rigorous validation and substantiation, these genes may assist in the development of surrogate markers for AgNP exposure and/or toxicity.

  13. Genomics-based screening of differentially expressed genes in the brains of mice exposed to silver nanoparticles via inhalation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hye-Young; Choi, You-Jin; Jung, Eun-Jung; Yin, Hu-Quan [Seoul National University, College of Pharmacy and Research Institute of Pharmaceutical Sciences (Korea, Republic of); Kwon, Jung-Taek; Kim, Ji-Eun; Im, Hwang-Tae; Cho, Myung-Haing [Seoul National University, College of Veterinary Medicine (Korea, Republic of); Kim, Ju-Han [Seoul National University, College of Medicine (Korea, Republic of); Kim, Hyun-Young [Occupational Safety and Health Research Institute, Chemical Safety and Health Research Center (Korea, Republic of); Lee, Byung-Hoon, E-mail: lee@snu.ac.k [Seoul National University, College of Pharmacy and Research Institute of Pharmaceutical Sciences (Korea, Republic of)

    2010-06-15

    Silver nanoparticles (AgNP) are among the fastest growing product categories in the nanotechnology industry. Despite the importance of AgNP in consumer products and clinical applications, relatively little is known regarding AgNP toxicity and its associated risks. We investigated the effects of AgNP on gene expression in the mouse brain using Affymetrix Mouse Genome Arrays. C57BL/6 mice were exposed to AgNP (geometric mean diameter, 22.18 {+-} 1.72 nm; 1.91 x 10{sup 7} particles/cm{sup 3}) for 6 h/day, 5 days/week using the nose-only exposure system for 2 weeks. Total RNA isolated from the cerebrum and cerebellum was subjected to hybridization. From over 39,000 probe sets, 468 genes in the cerebrum and 952 genes in the cerebellum were identified as AgNP-responsive (one-way analysis of variance; p < 0.05). The largest groups of gene products affected by AgNP exposure included 73 genes in the cerebrum and 144 genes in the cerebellum. AgNP exposure modulated the expression of several genes associated with motor neuron disorders, neurodegenerative disease, and immune cell function, indicating potential neurotoxicity and immunotoxicity associated with AgNP exposure. Real-time PCR data for five genes analyzed from whole blood showed good correlation with the observed changes in the brain. Following rigorous validation and substantiation, these genes may assist in the development of surrogate markers for AgNP exposure and/or toxicity.

  14. Updated and revised neutron reaction data for 237Np

    Directory of Open Access Journals (Sweden)

    Chen Guochang

    2017-01-01

    Full Text Available Nuclear data with high accuracy for minor actinides play an important role in nuclear technology applications, including reactor design and operation, fuel cycle, estimation of the amount of minor actinides in high burn-up reactors and the minor actinides transmutation. Based on the evaluated experimental data, the updated and revised evaluation of a full set of n+237Np nuclear data from 10−5 eV ∼ 20 MeV are carried out and recommended. Mainly revised quantities are neutron multiplicities from fission reaction, inelastic, fission, (n, 2n and (n, γ reaction cross sections as well as angular distribution and so on. The promising results are obtained when the renewal evaluated data of 237Np will be used to instead of the evaluated data in CENDL-3.1 database.

  15. np elastic scattering analyzing power characteristics at intermediate energies

    International Nuclear Information System (INIS)

    Abegg, R.; Davis, C.A.; Delheij, P.P.J.; Green, P.W.; Greeniaus, L.G.; Healey, D.C.; Miller, C.A.; Rodning, N.L.; Wait, G.D.; Ahmad, M.; Cairns, E.B.; Coombes, G.H.; Lapointe, C.; McDonald, W.J.; Moss, G.A.; Roy, G.; Soukup, J.; Tkachuk, R.R.; Ye, Y.; Watson, J.W.

    1989-06-01

    Recent measurements of charge symmetry breaking in the np system at 477 MeV, and of A oonn for np elastic scattering at 220, 325 and 425 MeV also yield accurate analyzing power data. These data allow the energy dependence of the analyzing power zero-crossing angle and the slope of the analyzing power at the zero-crossing to be determined. The incident neutron energies span a region where the zero-crossing angle is strongly energy dependent (Ε n n > 350 MeV). The results are compared to current phase shift analysis predictions, recently published LAMPF data, and the predictions of the Bonn and Paris potentials. (Author) 13 refs., 2 tabs., 2 figs

  16. Initial study of sediment antagonism and characteristics of silver nanoparticle-coated biliary stents in an experimental animal model.

    Science.gov (United States)

    Tian, Yigeng; Xia, Mingfeng; Zhang, Shuai; Fu, Zhen; Wen, Qingbin; Liu, Feng; Xu, Zongzhen; Li, Tao; Tian, Hu

    2016-01-01

    Plastic biliary stents used to relieve obstructive jaundice are frequently blocked by sediment, resulting in loss of drainage. We prepared stents coated with silver nanoparticles (AgNPs) and compared their ability to resist sedimentation with Teflon stents in a beagle model of obstructive jaundice. AgNP-coated Teflon biliary stents were prepared by chemical oxidation-reduction and evaluated in an obstructive jaundice model that was produced by ligation of common bile duct (CBD); animals were randomized to two equal groups for placement of AgNP-coated or Teflon control stents. Liver function and inflammatory index were found to be similar in the two groups, and the obstruction was relieved. Stents were removed 21 days after insertion and observed by scanning and transmission electron microscopy. The AgNP coating was analyzed by energy dispersive X-ray analysis (EDXA), and the composition of sediment was assayed by Fourier-transform infrared (FTIR) spectroscopy. Electron microscopy revealed a black, closely adherent AgNP stent coating, with thicknesses of 1.5-6 µm. Sediment thickness and density were greater on Teflon than on AgNP-coated stents. EDXA confirmed the stability and integrity of the AgNP coating before and after in vivo animal experimentation. FTIR spectroscopy identified stent sediment components including bilirubin, cholesterol, bile acid, protein, calcium, and other substances. AgNP-coated biliary stents resisted sediment accumulation in this canine model of obstructive jaundice caused by ligation of the CBD.

  17. Silver nanoparticle/bacterial cellulose gel membranes for antibacterial wound dressing: investigation in vitro and in vivo

    International Nuclear Information System (INIS)

    Wu, Jian; Zheng, Yudong; Wen, Xiaoxiao; Lin, Qinghua; Chen, Xiaohua; Wu, Zhigu

    2014-01-01

    Bacterial cellulose (BC) has attracted increasing attention as a novel wound dressing material, but its antimicrobial activity, which is one of the critical skin-barrier functions in wound healing, is not sufficient for use in practical applications. To overcome such a deficiency, silver nanoparticles were generated and self-assembled on the surface of BC nanofibers, forming a stable and evenly distributed Ag nanoparticle coated BC nanofiber (AgNP-BC). The performance of AgNP-BC was systematically studied in terms of antibacterial activities, cytocompatibility and effects on wound healing. The results showed that AgNP-BC exhibited significant antibacterial activity against Staphylococcus aureus. Moreover, AgNP-BC allowed attachment, and growth of rat fibroblasts with low cytotoxicity emerged. Based on these advantages, AgNP-BC samples were applied in a second-degree rat wound model. Wound flora showed a significant reduction during the healing. The fresh epidermal and dermis thicknesses with AgNP-BC samples were 111 and 855 µm respectively, higher than 74 and 619 µm for BC groups and 57 and 473 µm for untreated control wounds. The results demonstrated that AgNP-BC could reduce inflammation and promote scald wound healing. (paper)

  18. Ettevõtte edu sisse osta ei saa / Katrin Bats, Janne Laik, Silver Vohu, Evelin Ojamets ; intervjueerinud Küllike Heide

    Index Scriptorium Estoniae

    2012-01-01

    Kommunikatsiooni- ja turundustegevuse korraldusest ettevõtetes, mille suur osa antud projektidest hõlmab kõiki Balti riike. Mõtteid jagavad Katrin Bats Rimi Eesti Food AS-ist, Janne Laik NP Foods Eesti OÜ-st, Silver Vohu SEB Pangast ja Evelin Ojamets Coca-Cola-st

  19. Exploring the effect of silver nanoparticle size and medium composition on uptake into pulmonary epithelial 16HBE14o-cells

    NARCIS (Netherlands)

    Kettler, K.; Krystek, P.W.; Giannakou, C.; Hendriks, A.J.; de Jong, W.H.

    2016-01-01

    The increasing number of nanotechnology products on the market poses increasing human health risks by particle exposures. Adverse effects of silver nanoparticles (AgNPs) in various cell lines have been measured based on exposure dose after a fixed time point, but NP uptake kinetics and the

  20. Mycorrhizal fungi influence on silver uptake and membrane protein gene expression following silver nanoparticle exposure

    Energy Technology Data Exchange (ETDEWEB)

    Noori, Azam [State University of New York, College of Environmental Science and Forestry (United States); White, Jason C. [Connecticut Agricultural Experiment Station (United States); Newman, Lee A., E-mail: lanewman@esf.edu [State University of New York, College of Environmental Science and Forestry (United States)

    2017-02-15

    The rapid growth of nanotechnology and the high demand for nanomaterial use have greatly increased the risk of particle release into the environment. Understanding nanomaterial interactions with crop species and their associated microorganisms is critical to food safety and security. In the current study, tomato was inoculated with mycorrhizal fungi and subsequently exposed to 12, 24, or 36 mg/kg of 2- or 15-nm silver nanoparticles (Ag-NPs). Mycorrhizal (M) and non-mycorrhizal (NM) tomatoes exposed to 36 mg/kg of 2-nm Ag-NPs accumulated 1300 and 1600 μg/g silver in their tissues, respectively. Mycorrhizal plants accumulated 14% less silver compared to non-mycorrhizal plants. To begin to understand the mechanisms by which plants accumulate NPs, the expression of two aquaporin channel genes, the plasma membrane intrinsic protein (PIP) and the tonoplast membrane intrinsic protein (TIP), and one potassium channel (KC) gene were studied. In non-mycorrhizal plants, the expression of KC, PIP, and TIP was eight, five, and nine times higher than the control, respectively. These expressions for mycorrhizal plants were 5.8, 3.5, and 2 times higher than controls, respectively. The expression of KC and PIP, which are located on the plasma membrane, was 3.5 and 2.5, respectively, times higher than TIP, which is located on the tonoplast. PIP expression was significantly higher in NM tomatoes exposed to 12 mg/kg of 2-nm Ag-NPs compared to M plants. These results show that mycorrhizal colonization decreases Ag accumulation in NP-exposed plants and also moderates changes in expression level of membrane transport proteins.

  1. Mycorrhizal fungi influence on silver uptake and membrane protein gene expression following silver nanoparticle exposure

    International Nuclear Information System (INIS)

    Noori, Azam; White, Jason C.; Newman, Lee A.

    2017-01-01

    The rapid growth of nanotechnology and the high demand for nanomaterial use have greatly increased the risk of particle release into the environment. Understanding nanomaterial interactions with crop species and their associated microorganisms is critical to food safety and security. In the current study, tomato was inoculated with mycorrhizal fungi and subsequently exposed to 12, 24, or 36 mg/kg of 2- or 15-nm silver nanoparticles (Ag-NPs). Mycorrhizal (M) and non-mycorrhizal (NM) tomatoes exposed to 36 mg/kg of 2-nm Ag-NPs accumulated 1300 and 1600 μg/g silver in their tissues, respectively. Mycorrhizal plants accumulated 14% less silver compared to non-mycorrhizal plants. To begin to understand the mechanisms by which plants accumulate NPs, the expression of two aquaporin channel genes, the plasma membrane intrinsic protein (PIP) and the tonoplast membrane intrinsic protein (TIP), and one potassium channel (KC) gene were studied. In non-mycorrhizal plants, the expression of KC, PIP, and TIP was eight, five, and nine times higher than the control, respectively. These expressions for mycorrhizal plants were 5.8, 3.5, and 2 times higher than controls, respectively. The expression of KC and PIP, which are located on the plasma membrane, was 3.5 and 2.5, respectively, times higher than TIP, which is located on the tonoplast. PIP expression was significantly higher in NM tomatoes exposed to 12 mg/kg of 2-nm Ag-NPs compared to M plants. These results show that mycorrhizal colonization decreases Ag accumulation in NP-exposed plants and also moderates changes in expression level of membrane transport proteins.

  2. Learning optimal quantum models is NP-hard

    Science.gov (United States)

    Stark, Cyril J.

    2018-02-01

    Physical modeling translates measured data into a physical model. Physical modeling is a major objective in physics and is generally regarded as a creative process. How good are computers at solving this task? Here, we show that in the absence of physical heuristics, the inference of optimal quantum models cannot be computed efficiently (unless P=NP ). This result illuminates rigorous limits to the extent to which computers can be used to further our understanding of nature.

  3. On reducibility and symmetry of disjoint NP pairs

    Czech Academy of Sciences Publication Activity Database

    Pudlák, Pavel

    2003-01-01

    Roč. 295, - (2003), s. 323-339 ISSN 0304-3975 R&D Projects: GA AV ČR IAA1019901; GA MŠk LN00A056 Institutional research plan: CEZ:AV0Z1019905; CEZ:AV0Z1019905 Keywords : disjoint NP-pairs * polynomial reducibility * propositional proof systems Subject RIV: BA - General Mathematics Impact factor: 0.764, year: 2003

  4. Measurements of {sup 237}Np secondary neutron spectra

    Energy Technology Data Exchange (ETDEWEB)

    Kornilov, N.V.

    1997-03-01

    The activities carried out during the first year of the project are summarized. The main problems for Np spectra measurements arise from high intrinsic gamma-ray activity of the sample and admixture of the oxygen and iron nuclei. The inelastically scattered neutrons and the fission neutrons spectra for {sup 237}Np were measured by time-of-flight spectrometer of the IPPE at incident neutron energies {approx_equal}1.5 MeV, and {approx_equal}0.5 MeV. A solid tritium target and a Li-metallic target were used as neutron sources. The neutron scattering on C sample (C(n,n) standard reaction) was measured to normalize the Np data. The experimental data should be simulated by Monte Carlo method to correct the experimental data for oxygen and iron admixture as well as for multiple scattering of the neutrons in the sample. Therefore the response function of the spectrometer, and the neutron energy distribution from the source were investigated in detail. (author)

  5. Size-Controlled Dissolution of Organic-Coated Silver Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Rui; Levard, Clément; Marinakos, Stella M.; Cheng, Yingwen; Liu, Jie; Michel, F. Marc; Brown, Jr., Gordon E.; Lowry, Gregory V. (Duke)

    2012-04-02

    The solubility of Ag NPs can affect their toxicity and persistence in the environment. We measured the solubility of organic-coated silver nanoparticles (Ag NPs) having particle diameters ranging from 5 to 80 nm that were synthesized using various methods, and with different organic polymer coatings including poly(vinylpyrrolidone) and gum arabic. The size and morphology of Ag NPs were characterized by transmission electron microscopy (TEM). X-ray absorption fine structure (XAFS) spectroscopy and synchrotron-based total X-ray scattering and pair distribution function (PDF) analysis were used to determine the local structure around Ag and evaluate changes in crystal lattice parameters and structure as a function of NP size. Ag NP solubility dispersed in 1 mM NaHCO{sub 3} at pH 8 was found to be well correlated with particle size based on the distribution of measured TEM sizes as predicted by the modified Kelvin equation. Solubility of Ag NPs was not affected by the synthesis method and coating as much as by their size. Based on the modified Kelvin equation, the surface tension of Ag NPs was found to be {approx}1 J/m{sup 2}, which is expected for bulk fcc (face centered cubic) silver. Analysis of XAFS, X-ray scattering, and PDFs confirm that the lattice parameter, {alpha}, of the fcc crystal structure of Ag NPs did not change with particle size for Ag NPs as small as 6 nm, indicating the absence of lattice strain. These results are consistent with the finding that Ag NP solubility can be estimated based on TEM-derived particle size using the modified Kelvin equation for particles in the size range of 5-40 nm in diameter.

  6. Silver nanoparticles reduce brain inflammation and related neurotoxicity through induction of H2S-synthesizing enzymes

    Science.gov (United States)

    Gonzalez-Carter, Daniel A.; Leo, Bey Fen; Ruenraroengsak, Pakatip; Chen, Shu; Goode, Angela E.; Theodorou, Ioannis G.; Chung, Kian Fan; Carzaniga, Raffaella; Shaffer, Milo S. P.; Dexter, David T.; Ryan, Mary P.; Porter, Alexandra E.

    2017-03-01

    Silver nanoparticles (AgNP) are known to penetrate into the brain and cause neuronal death. However, there is a paucity in studies examining the effect of AgNP on the resident immune cells of the brain, microglia. Given microglia are implicated in neurodegenerative disorders such as Parkinson’s disease (PD), it is important to examine how AgNPs affect microglial inflammation to fully assess AgNP neurotoxicity. In addition, understanding AgNP processing by microglia will allow better prediction of their long term bioreactivity. In the present study, the in vitro uptake and intracellular transformation of citrate-capped AgNPs by microglia, as well as their effects on microglial inflammation and related neurotoxicity were examined. Analytical microscopy demonstrated internalization and dissolution of AgNPs within microglia and formation of non-reactive silver sulphide (Ag2S) on the surface of AgNPs. Furthermore, AgNP-treatment up-regulated microglial expression of the hydrogen sulphide (H2S)-synthesizing enzyme cystathionine-γ-lyase (CSE). In addition, AgNPs showed significant anti-inflammatory effects, reducing lipopolysaccharide (LPS)-stimulated ROS, nitric oxide and TNFα production, which translated into reduced microglial toxicity towards dopaminergic neurons. Hence, the present results indicate that intracellular Ag2S formation, resulting from CSE-mediated H2S production in microglia, sequesters Ag+ ions released from AgNPs, significantly limiting their toxicity, concomitantly reducing microglial inflammation and related neurotoxicity.

  7. Shape- and Size-Controlled Synthesis of Silver Nanoparticles Using Aloe vera Plant Extract and Their Antimicrobial Activity

    Science.gov (United States)

    Logaranjan, Kaliyaperumal; Raiza, Anasdass Jaculin; Gopinath, Subash C. B.; Chen, Yeng; Pandian, Kannaiyan

    2016-11-01

    Biogenic synthesis of silver nanoparticles (AgNP) was performed at room temperature using Aloe vera plant extract in the presence of ammoniacal silver nitrate as a metal salt precursor. The formation of AgNP was monitored by UV-visible spectroscopy at different time intervals. The shape and size of the synthesized particle were visualized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. These results were confirmed by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses and further supported by surface-enhanced Raman spectroscopy/Raman scattering (SERS) study. UV-visible spectrum has shown a sharp peak at 420 nm and further evidenced by FTIR peak profile (at 1587.6, 1386.4, and 1076 cm-1 with corresponding compounds). The main band position with SERS was noticed at 1594 cm-1 (C-C stretching vibration). When samples were heated under microwave radiation, AgNP with octahedron shapes with 5-50 nm were found and this method can be one of the easier ways to synthesis anisotropic AgNP, in which the plant extract plays a vital role to regulate the size and shape of the nanoparticles. Enhanced antibacterial effects (two- to fourfold) were observed in the case of Aloe vera plant protected AgNP than the routinely synthesized antibiotic drugs.

  8. Characterization of Electrochemically Generated Silver

    Science.gov (United States)

    Adam, Niklas; Martinez, James; Carrier, Chris

    2014-01-01

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

  9. Supported quantum clusters of silver as enhanced catalysts for reduction

    Directory of Open Access Journals (Sweden)

    Leelavathi Annamalai

    2011-01-01

    Full Text Available Abstract Quantum clusters (QCs of silver such as Ag7(H2MSA7, Ag8(H2MSA8 (H2MSA, mercaptosuccinic acid were synthesized by the interfacial etching of Ag nanoparticle precursors and were loaded on metal oxide supports to prepare active catalysts. The supported clusters were characterized using high resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and laser desorption ionization mass spectrometry. We used the conversion of nitro group to amino group as a model reaction to study the catalytic reduction activity of the QCs. Various aromatic nitro compounds, namely, 3-nitrophenol (3-np, 4-nitrophenol (4-np, 3-nitroaniline (3-na, and 4-nitroaniline (4-na were used as substrates. Products were confirmed using UV-visible spectroscopy and electrospray ionization mass spectrometry. The supported QCs remained active and were reused several times after separation. The rate constant suggested that the reaction followed pseudo-first-order kinetics. The turn-over frequency was 1.87 s-1 per cluster for the reduction of 4-np at 35°C. Among the substrates investigated, the kinetics followed the order, SiO2 > TiO2 > Fe2O3 > Al2O3.

  10. Source of cytotoxicity in a colloidal silver nanoparticle suspension.

    Science.gov (United States)

    Hatipoglu, Manolya Kukut; Keleştemur, Seda; Altunbek, Mine; Culha, Mustafa

    2015-05-15

    Silver nanoparticles (AgNPs) are increasingly used in a variety of applications because of their potential antimicrobial activity and their plasmonic and conductivity properties. In this study, we investigated the source of cytotoxicity, genotoxicity, and reactive oxygen species (ROS) production on human dermal fibroblast and human lung cancer (A549) cell lines upon exposure to AgNP colloidal suspensions prepared with the simplest and most commonly used Lee–Meisel method with a variety of reaction times and the concentrations of the reducing agent. The AgNPs synthesized with shorter reaction times were more cytotoxic and genotoxic due to the presence of a few nanometer-sized AgNP seeds. The suspensions prepared with an increased citrate concentration were not cytotoxic, but they induced more ROS generation on A549 cells due to the high citrate concentration. The genotoxicity of the suspension decreased significantly at the higher citrate concentrations. The analysis of both transmission electron microscopy images from the dried droplet areas of the colloidal suspensions and toxicity data indicated that the AgNP seeds were the major source of toxicity. The completion of the nucleation step and the formation of larger AgNPs effectively decreased the toxicity.

  11. Opportunity's View After Drive on Sol 1806

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings just after driving 60.86 meters (200 feet) on the 1,806th Martian day, or sol, of Opportunity's surface mission (Feb. 21, 2009). North is at the center; south at both ends. Tracks from the drive extend northward across dark-toned sand ripples and light-toned patches of exposed bedrock in the Meridiani Planum region of Mars. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). Engineers designed the Sol 1806 drive to be driven backwards as a strategy to redistribute lubricant in the rovers wheels. The right-front wheel had been showing signs of increased friction. The rover's position after the Sol 1806 drive was about 2 kilometer (1.2 miles) south southwest of Victoria Crater. Cumulative odometry was 14.74 kilometers (9.16 miles) since landing in January 2004, including 2.96 kilometers (1.84 miles) since climbing out of Victoria Crater on the west side of the crater on Sol 1634 (August 28, 2008). This view is presented as a cylindrical projection with geometric seam correction.

  12. SOL: INNOVACIÓN ON-LINE

    Directory of Open Access Journals (Sweden)

    Rubén Faúndez

    2007-11-01

    Full Text Available Las aplicaciones de simulación tienden a ser cada vez más cercanas a usuarios e industrias. Sin embargo, muchas de ellas no poseen ni la capacidad ni el conocimiento como para desarrollar internamente sus modelos de simulación. Por este motivo, y como una forma de apoyar la toma de decisiones basándose en modelos de simulación, se presenta la plataforma SOL (Simulación On Line. La metodología completa de trabajo, así como la interacción entre SOL, Empresa y Asesor, son presentadas. Su base de datos, los niveles de usuarios, sus funcionalidades, y la creación automatizada de información grafica y visual, también son explicadas. En el caso de aplicación, el uso de SOL para apoyar la toma de decisiones en una operación de movimiento de material, permite a los tomadores de decisión acceder a análisis robustos basados en información extraída de los modelos de simulación. SOL, al almacenar información, funcionar vía web, generar análisis automatizados y crear visualizaciones, permite cumplir con las expectativas de los usuarios respecto a una solución integral en simulación.

  13. Sol-Gel Synthesis Of Aluminoborosilicate Powders

    Science.gov (United States)

    Bull, Jeffrey; Leiser, Daniel; Selvaduray, Guna

    1992-01-01

    Application of sol-gel process to synthesis of aluminoborosilicate powders shows potential for control of microstructures of materials. Development of materials having enhanced processing characteristics prove advantageous in extending high-temperature endurance of fibrous refractory composite insulation made from ceramic fibers.

  14. Fluorescence metrology of silica sol-gels

    Indian Academy of Sciences (India)

    We have developed a new method for measuring in-situ the growth of the nanometre-size silica particles which lead to the formation of sol-gel glasses. This technique is based on the decay of fluorescence polarisation anisotropy due to Brownian rotation of dye molecules bound to the particles. Results to date give near ...

  15. Silver matrix composites reinforced with galvanically silvered particles

    OpenAIRE

    J. Śleziona; J. Wieczorek,

    2007-01-01

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

  16. Photocatalytic and biocidal activities of novel coating systems of mesoporous and dense TiO{sub 2}-anatase containing silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Roldán, María V. [Laboratorio de Materiales Cerámicos, FCEIA-UNR, IFIR-CONICET, Pellegrini 250, Rosario S2000BTP (Argentina); Oña, Paula de [Laboratorio de Microbiología Molecular, FCByF-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Castro, Yolanda; Durán, Alicia [Instituto de Cerámica y Vidrio (CSIC), Campus de Cantoblanco, 28049, Madrid (Spain); Faccendini, Pablo; Lagier, Claudia [IQUIR-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Grau, Roberto, E-mail: robertograu@fulbrightmail.org [Laboratorio de Microbiología Molecular, FCByF-UNR-CONICET, Suipacha 531, Rosario S2002LRK (Argentina); Pellegri, Nora S., E-mail: pellegri@fceia.unr.edu.ar [Laboratorio de Materiales Cerámicos, FCEIA-UNR, IFIR-CONICET, Pellegrini 250, Rosario S2000BTP (Argentina)

    2014-10-01

    Here we describe the development of novel nanostructured coating systems with improved photocatalytic and antibacterial activities. These systems comprise a layer of SiO{sub 2} followed by a layer of mesoporous or dense TiO{sub 2}-anatase, and doping with silver nanoparticles (Ag NPs). The coatings were synthesized via a sol–gel technique by combining colloidal Ag NPs with TiO{sub 2} and SiO{sub 2} sols. The photocatalytic activity was studied through methyl orange decomposition under UV light. Results showed a great increase of photocatalytic activity by Ag NPs doping. The most active photocatalyst corresponded to the Ag–SiO{sub 2}/TiO{sub 2} mesoporous system, associated with the porosity of the coatings and with the decrease of e–h recombination for the presence of Ag NPs. All the TiO{sub 2} coatings showed a strong bactericidal activity against planktonic forms of Gram-negative (enterohemorrhagic Escherichia coli) and Gram-positive (Listeria monocytogenes) pathogens, as well as a strong germicidal effect against deadly spores of human gas gangrene- and anthrax-producing bacteria (Clostridium perfringens and Bacillus anthracis, respectively). The bactericidal and sporocidal activity was improved by doping the coatings with Ag NPs, even more when nanoparticles were in the outer layer of TiO{sub 2}, because they are more accessible to the environment. The mechanisms responsible for the increase of photocatalytic and bactericidal behaviors related to Ag NP doping were studied by spectroscopic ellipsometry, UV–vis spectroscopy, photoluminescence and anodic stripping voltammetry. It was found that the separation of the electron–hole pair contributed to the enhancement of photocatalysis, whereas the effect of the local electric field reinforcement was probably present. A possible involvement of a decrease of band-gap energy and dispersion by silver nanoparticles is ruled out. bactericidal efficacy was increased by Ag{sup +} ion release. Overall, the results

  17. Facile preparation of water dispersible polypyrrole nanotube-supported silver nanoparticles for hydrogen peroxide reduction and surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Peng Yingjing; Qiu Lihua; Pan Congtao; Wang Cancan; Shang Songmin; Yan Feng

    2012-01-01

    Water dispersible polypyrrole nanotube/silver nanoparticle hybrids (PPyNT-COOAgNP) were synthesized via a cation-exchange method. The approach involves the surface functionalization of PPyNTs with carboxylic acid groups (-COOH), and cation-exchange with silver ions (Ag + ) and followed by the reduction of metal ions. The morphology and optical properties of the produced PPyNT-COOAgNP nanohybrids were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrometer, and UV–vis spectroscopy. The as-prepared PPyNT-COOAgNP nanohybrids exhibited well-defined response to the reduction of hydrogen peroxide, and as extremely suitable substrates for surface-enhanced Raman spectroscopy (SERS) with a high enhancement factor of 6.0 × 10 7 , and enabling the detection of 10 −12 M Rhodamine 6G solution.

  18. Sol-gel additive for systems with inorganic binders

    International Nuclear Information System (INIS)

    Akstinat, M.; Antenen, D.; Suter, W.

    1996-01-01

    A sol-gel additive for inorganic binder systems and sol-gel process for producing air-placed concrete and mortar by using such sol-gel additives are disclosed. Sol-gel additives for gel-derived inorganic binder systems (for example plaster, cement, lime, special slags, etc.) marked improve the consistency of such binder systems during processing or allow their consistency to be regulated. In addition, these sol-gel additives regulate setting times and substantially improve durability (chemical resistance, reduced permeability) and the mechanical properties of the set binder system. (author)

  19. Nucleic acid nanomaterials: Silver-wired DNA

    Science.gov (United States)

    Auffinger, Pascal; Ennifar, Eric

    2017-10-01

    DNA double helical structures are supramolecular assemblies that are typically held together by classical Watson-Crick pairing. Now, nucleotide chelation of silver ions supports an extended silver-DNA hybrid duplex featuring an uninterrupted silver array.

  20. Genetics Home Reference: Russell-Silver syndrome

    Science.gov (United States)

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

  1. Silver against Pseudomonas aeruginosa biofilms

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  2. Linear thermal expansion, thermal diffusivity and melting temperature of Am-MOX and Np-MOX

    International Nuclear Information System (INIS)

    Prieur, D.; Belin, R.C.; Manara, D.; Staicu, D.; Richaud, J.-C.; Vigier, J.-F.; Scheinost, A.C.; Somers, J.; Martin, P.

    2015-01-01

    Highlights: • The thermal properties of Np- and Am-MOX solid solutions were investigated. • Np- and Am-MOX solid solutions exhibit the same linear thermal expansion. • The thermal conductivity of Am-MOX is about 10% higher than that of Np-MOX. • The melting temperatures of Np-MOX and Am-MOX are 3020 ± 30 K and 3005 ± 30 K, respectively. - Abstract: The thermal properties of Np- and Am-MOX solid solution materials were investigated. Their linear thermal expansion, determined using high temperature X-ray diffraction from room temperature to 1973 K showed no significant difference between the Np and the Am doped MOX. The thermal conductivity of the Am-MOX is about 10% higher than that of Np-MOX. The melting temperatures of Np-MOX and Am-MOX, measured using a laser heating self crucible arrangement were 3020 ± 30 K and 3005 ± 30 K, respectively

  3. VizieR Online Data Catalog: Photometry and spectroscopy of NP Per (Lacy+, 2016)

    Science.gov (United States)

    Lacy, C. H. S.; Fekel, F. C.; Pavlovski, K.; Torres, G.; Muterspaugh, M. W.

    2016-09-01

    From 2011 November through 2014 November, we acquired 56 high-quality spectra of NP Per with the Tennessee State University 2m Automatic Spectroscopic Telescope (AST) and a fiber-fed echelle spectrograph at Fairborn Observatory in southeast Arizona. Of these spectra, 55 were suitable for radial velocity measurements (see Table1). The detector for these observations was a Fairchild 486 CCD, having 4096*4096 15μ pixels. While the spectrograms have 48 orders ranging from 3800 to 8260Å, we have used just the orders that cover the wavelength region from 4920 to 7100Å. We made our observations with a fiber that produced a spectral resolution of 0.4Å, corresponding to a resolving power of 15000 at 6000Å. Our spectra have typical signal-to-noise ratios (S/Ns) of 40 at 6000Å. We began V-band photometric observations of NP Per with the URSA WebScope on 2003 December 2. URSA is a 10inch Schmidt-Cassegrain telescope made by Meade Instruments Corp., equipped with a V-band filter and a Santa Barbara Instruments Group ST8 CCD camera, housed in a Technical Innovations RoboDome, all controlled by a Macintosh computer in a control room under the observing deck of Kimpel Hall on the University of Arkansas campus at Fayetteville. A larger telescope, the NFO WebScope, was brought to bear on 2005 February 27. Nearly all the observations after this date were obtained with the NFO, which is a robotic 24inch Cassegrain reflector located near Silver City, NM, USA. Both telescopes used Bessel V filters consisting of 2.0mm of GG495 and 3.0mm of BG 39. Exposures were 120 seconds long for both telescopes, and the cadence was typically 150 seconds per image. The images contained the variable star (TYC 2371-0390-1=BD +31 0729) and 2 comparison stars (TYC 2371-156-1 and TYC 2371-1034-1) of approximately the same brightness and color as the variable star. The observations are given in Table6 for the URSA WebScope and in Table7 for the NFO WebScope. Dates of eclipses obtained from the

  4. Modulation of Human Macrophage Responses to Mycobacterium tuberculosis by Silver Nanoparticles of Different Size and Surface Modification.

    Directory of Open Access Journals (Sweden)

    Srijata Sarkar

    Full Text Available Exposure to silver nanoparticles (AgNP used in consumer products carries potential health risks including increased susceptibility to infectious pathogens. Systematic assessments of antimicrobial macrophage immune responses in the context of AgNP exposure are important because uptake of AgNP by macrophages may lead to alterations of innate immune cell functions. In this study we examined the effects of exposure to AgNP with different particle sizes (20 and 110 nm diameters and surface chemistry (citrate or polyvinlypyrrolidone capping on cellular toxicity and innate immune responses against Mycobacterium tuberculosis (M.tb by human monocyte-derived macrophages (MDM. Exposures of MDM to AgNP significantly reduced cellular viability, increased IL8 and decreased IL10 mRNA expression. Exposure of M.tb-infected MDM to AgNP suppressed M.tb-induced expression of IL1B, IL10, and TNFA mRNA. Furthermore, M.tb-induced IL-1β, a cytokine critical for host resistance to M.tb, was inhibited by AgNP but not by carbon black particles indicating that the observed immunosuppressive effects of AgNP are particle specific. Suppressive effects of AgNP on the M.tb-induced host immune responses were in part due to AgNP-mediated interferences with the TLR signaling pathways that culminate in the activation of the transcription factor NF-κB. AgNP exposure suppressed M.tb-induced expression of a subset of NF-κB mediated genes (CSF2, CSF3, IFNG, IL1A, IL1B, IL6, IL10, TNFA, NFKB1A. In addition, AgNP exposure increased the expression of HSPA1A mRNA and the corresponding stress-induced Hsp72 protein. Up-regulation of Hsp72 by AgNP can suppress M.tb-induced NF-κB activation and host immune responses. The observed ability of AgNP to modulate infectious pathogen-induced immune responses has important public health implications.

  5. Structural features of silver-doped phosphate glasses in zone of femtosecond laser-induced modification

    Energy Technology Data Exchange (ETDEWEB)

    Vasileva, A.A., E-mail: anvsilv@gmail.com [Saint-Petersburg State University, Institute of Chemistry, Saint-Petersburg (Russian Federation); Nazarov, I.A. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg (Russian Federation); Olshin, P.K.; Povolotskiy, A.V. [Saint-Petersburg State University, Institute of Chemistry, Saint-Petersburg (Russian Federation); Sokolov, I.A. [St.Petersburg State Polytechnical University, St.Petersburg (Russian Federation); LTD “AtomTjazhMash”, St.Petersburg (Russian Federation); Manshina, A.A. [Saint-Petersburg State University, Institute of Chemistry, Saint-Petersburg (Russian Federation)

    2015-10-15

    Femtosecond (fs) laser writing of two-dimensional microstructures (waveguides) is demonstrated in bulk phosphate glasses doped with silver ions. Silver-content phosphate and silver-content niobium–phosphate glasses with high concentration of silver oxide 55 mol% were used as samples for fs laser writing. The chemical network structure of the synthesized samples is analyzed through Raman spectroscopy and was found to be strongly sensitive to Nb incorporation. It was found that the direct laser writing process enables not only reorganization of glass network, but also formation of color centers and silver nanoparticles that are revealed in appearance of luminescence signal and plasmon absorption. The process of NPs' formation is more efficient for Nb-phosphate glass, while color centers are preferably formed in phosphate glass. - Graphical abstract: Formation of silver NPs on the surface of 0.5Ag{sub 2}O–0.4P{sub 2}O{sub 5}–0,1Nb{sub 2}O{sub 5} glass induced by CW laser irradiation. - Highlights: • The structure of 0.5Ag{sub 2}O–0.1Nb{sub 2}O{sub 5}–0.4P{sub 2}O{sub 5} and 0.55Ag{sub 2}O–0.45P{sub 2}O{sub 5} glasses was investigated by Raman spectroscopy. • Fs laser writing induces formation of silver NPs in investigated glasses. • Surface plasmon resonance in the absorption spectra confirms the formation of NP. • The possibility of CW laser induced formation of silver NPs on the surface of sample with niobium is shown.

  6. Structural features of silver-doped phosphate glasses in zone of femtosecond laser-induced modification

    International Nuclear Information System (INIS)

    Vasileva, A.A.; Nazarov, I.A.; Olshin, P.K.; Povolotskiy, A.V.; Sokolov, I.A.; Manshina, A.A.

    2015-01-01

    Femtosecond (fs) laser writing of two-dimensional microstructures (waveguides) is demonstrated in bulk phosphate glasses doped with silver ions. Silver-content phosphate and silver-content niobium–phosphate glasses with high concentration of silver oxide 55 mol% were used as samples for fs laser writing. The chemical network structure of the synthesized samples is analyzed through Raman spectroscopy and was found to be strongly sensitive to Nb incorporation. It was found that the direct laser writing process enables not only reorganization of glass network, but also formation of color centers and silver nanoparticles that are revealed in appearance of luminescence signal and plasmon absorption. The process of NPs' formation is more efficient for Nb-phosphate glass, while color centers are preferably formed in phosphate glass. - Graphical abstract: Formation of silver NPs on the surface of 0.5Ag 2 O–0.4P 2 O 5 –0,1Nb 2 O 5 glass induced by CW laser irradiation. - Highlights: • The structure of 0.5Ag 2 O–0.1Nb 2 O 5 –0.4P 2 O 5 and 0.55Ag 2 O–0.45P 2 O 5 glasses was investigated by Raman spectroscopy. • Fs laser writing induces formation of silver NPs in investigated glasses. • Surface plasmon resonance in the absorption spectra confirms the formation of NP. • The possibility of CW laser induced formation of silver NPs on the surface of sample with niobium is shown

  7. Gilded Silver Mask

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    This gilded silver mask from the Liao Dynasty is 31 cm long and 22.2 cm wide. The plump oval face was designed with a protruding brow ridge, narrow eyes, high-bridged nose and closed mouth. The chin is slightly round against a thin neck, the ears are long and the hair can be clearly seen from the finely carved lines. The use of masks was recorded as

  8. Interaction study of rice stripe virus proteins reveals a region of the nucleocapsid protein (NP) required for NP self-interaction and nuclear localization.

    Science.gov (United States)

    Lian, Sen; Cho, Won Kyong; Jo, Yeonhwa; Kim, Sang-Min; Kim, Kook-Hyung

    2014-04-01

    Rice stripe virus (RSV), which belongs to the genus Tenuivirus, is an emergent virus problem. The RSV genome is composed of four single-strand RNAs (RNA1-RNA4) and encodes seven proteins. We investigated interactions between six of the RSV proteins by yeast-two hybrid (Y2H) assay in vitro and by bimolecular fluorescence complementation (BiFC) in planta. Y2H identified self-interaction of the nucleocapsid protein (NP) and NS3, while BiFC revealed self-interaction of NP, NS3, and NCP. To identify regions(s) and/or crucial amino acid (aa) residues required for NP self-interaction, we generated various truncated and aa substitution mutants. Y2H assay showed that the N-terminal region of NP (aa 1-56) is necessary for NP self-interaction. Further analysis with substitution mutants demonstrated that additional aa residues located at 42-47 affected their interaction with full-length NP. These results indicate that the N-terminal region (aa 1-36 and 42-47) is required for NP self-interaction. BiFC and co-localization studies showed that the region required for NP self-interaction is also required for NP localization at the nucleus. Overall, our results indicate that the N-terminal region (aa 1-47) of the NP is important for NP self-interaction and that six aa residues (42-47) are essential for both NP self-interaction and nuclear localization. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Biological synthesis of silver nanoparticles

    International Nuclear Information System (INIS)

    Maliszewska, I; Szewczyk, K; Waszak, K

    2009-01-01

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

  10. MOD silver metallization for photovoltaics

    Science.gov (United States)

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

    1984-01-01

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

  11. Silver precipitation from electrolytic effluents

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  12. Evaluation of the (n,p) and (n,np) reactions of the isotopes of titanium for ENDF/B-IV

    International Nuclear Information System (INIS)

    Magurno, B.A.

    1975-01-01

    Threshold detectors generally use elemental titanium rather than isotopically enriched samples necessitating the evaluation of all the (n,p), (n,np), and (n,d) reactions of the major contributing isotopes separately. 49 Ti and 50 Ti are not dealt with here since they are both approximately 5 percent abundant and have small cross sections. The (n,np), (n,pn) and (n,d) reactions are lumped together and called (n,np). The energy range is divided into three regions. Region I is that of threshold to 7 MeV, Region II, 7 to 12 MeV and Region III, 12 to 20 MeV

  13. Characterization of oxalate-based 237NpO2 powder

    International Nuclear Information System (INIS)

    Rankin, D.T.; Burney, G.A.; Smith, P.K.; Sisson, R.D.

    1976-01-01

    238 Pu, a radioisotope heat source, is produced by irradiating reactor targets containing 237 NpO 2 . The neptunium oxide is obtained by precipitating and calcining 237 Np(IV) oxalate. The effects of oxalate precipitation parameters on particle morphology and size distribution of 237 NpO 2 powder were established to provide process controls for fabricating reactor targets

  14. Ozonation and sol-gel method to obtain Cu/Cu O nanoparticles from cyanidation wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Soria A, M. J.; Puente S, D. M.; Carrillo P, F. R. [Universidad Autonoma de Coahuila, Facultad de Metalurgia, Carretera 57 Km 4.5, 25710 Monclova, Coahuila (Mexico); Garcia C, L. A. [Centro de Investigacion en Quimica Aplicada, Blvd. Enrique Reyna No. 140, Col. Los Pinos, 25253 Saltillo, Coahuila (Mexico); Velazquez S, J., E-mail: frrcarrillo@yahoo.com.mx [University of Texas at San Antonio, Department of Physics and Astronomy, San Antonio TX 78249 (United States)

    2015-07-01

    The extraction process of gold and silver by cyanidation generates large amounts of effluent which also contain contaminants such as cyanide and significant metal values such as copper. This paper presents the results of the removal and recovery of copper from ozonation treatment of a residual aqueous cyanide. The residual solution was treated by ozonation-precipitation to obtain a precipitate of copper. From this, copper nano composites obtained by Pechini modified sol-gel method were obtained. The compounds obtained were characterized by X-ray diffraction, showing a dependence of the type of compounds formed over time of ozonation and heat treatment of the gel. The particle size was measured by scanning electron microscopy and calculated by the Scherrer equation, being between 50 and 120 nm. (Author)

  15. Morphological, Structural, and Electrical Characterization of Sol-Gel-Synthesized ZnO Nano rods

    International Nuclear Information System (INIS)

    Kashif, M.; Hashim, U.; Foo, K.L.; Ali, M.E.; Ali, M.E.; Ali, S.M.U.

    2013-01-01

    ZnO nano rods were grown on thermally oxidized p-type silicon substrate using sol-gel method. The SEM image revealed high-density, well-aligned, and perpendicular ZnO nano rods on the oxidized silicon substrate. The XRD profile confirmed the c-axis orientation of the nano rods. PL measurements showed the synthesized ZnO nano rods have strong ultraviolet (UV) emission. The electrical characterization was performed using interdigitated silver electrodes to investigate the stability in the current flow of the fabricated device under different ultraviolet (UV) exposure times. It was notified that a stable current flow was observed after 60 min of UV exposure. The determination of stable current flow after UV exposure is necessary for UV-based gas sensing and optoelectronic devices.

  16. Effects of silver nanoparticles on survival, biomass change and avoidance behaviour of the endogeic earthworm Allolobophora chlorotica.

    Science.gov (United States)

    Brami, C; Glover, A R; Butt, K R; Lowe, C N

    2017-07-01

    Increasing commercial application of silver nanoparticles (Ag NP) and subsequent presence in wastewater and sewage sludge has raised concerns regarding their effects in the aquatic and terrestrial environment. Several studies have employed standardised acute and chronic earthworm-based tests to establish the toxicological effects of Ag NP within soil. These studies have relied heavily on the use of epigiec earthworm species which may have limited ecological relevance in mineral soil. This study assessed the influence of Ag NP (uncoated 80nm powder) and AgNO 3 on survival, change in biomass and avoidance behaviour in a soil dwelling (endogiec) species, Allolobophora chlorotica. Earthworms were exposed for 14 days to soils spiked with Ag NP or AgNO 3 at 0, 12.5, 25, 50 and 100mgkg -1 either separately for survival and biomass measurement, or combined within a linear gradient to assess avoidance. Avoidance behaviour was shown to provide the most sensitive endpoint with an observable effect at an Ag NP/AgNO 3 concentration of 12.5mgkg -1 compared with 50mgkg -1 for biomass change and 100mgkg -1 for survival. Greater mortality was observed in AgNO 3 (66.7%) compared with Ag NP-spiked soils (12.5%) at 100mgkg -1 , attributed to increased presence of silver ions. Although comparison of results with studies employing Eisenia fetida and Eisenia andrei suggest that the A. chlorotica response to Ag NP is more sensitive, further research employing both epigeic and endogeic earthworms under similar experimental conditions is required to confirm this observation. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Transport of silver nanoparticles from nanocomposite Ag/alginate hydrogels under conditions mimicking tissue implantation

    Directory of Open Access Journals (Sweden)

    Kostić Danijela D.

    2017-01-01

    Full Text Available The aim of this work was to assess phenomena occurring during AgNP transport from nanocomposite Ag/alginate hydrogels under conditions relevant for potential biomedical applications as antimicrobial soft tissue implants. First, we have studied AgNP migration from the nanocomposite to the adjacent alginate hydrogel mimicking soft tissue next to the implant. AgNP deposition was carried out by the initial burst release lasting for ∼24 h yielding large aggregates on hydrogel surfaces and smaller clusters (∼400 nm in size inside. However, the overall released content was low (0.67% indicating high nanocomposite stability. In the next experimental series, release of AgNPs, 10–30 nm in size, from Ag/alginate microbeads in water was investigated under static conditions as well as under continuous perfusion mimicking vascularized tissues. Mathematical modeling has revealed AgNP release by diffusion under static conditions with the diffusion coefficient within the Ag/alginate hydrogel of 6.9x10–19 m2 s–1. Conversely, continuous perfusion induced increased AgNP release by convection with the interstitial fluid velocity estimated as 4.6 nm s–1. Overall, the obtained results indicated the influence of hydrodynamic conditions at the implantation site on silver release and potential implant functionality, which should be investigated at the experimentation beginning using appropriate in vitro systems. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45019

  18. Impacts of Silver Nanoparticle Ingestion on Pigmentation and Developmental Progression in Drosophila

    Directory of Open Access Journals (Sweden)

    S. Catherine Silver Key

    2011-10-01

    Full Text Available In recent years, the advent of nanomaterial use has increased exposure rates and raised health concerns. However, the toxicology profiles of many nanomaterials are far from complete for various reasons. In this study, Drosophila melanogaster, commonly called fruit flies, were exposed to one of the most widely used nanomaterials, silver nanopowder (Ag NP, to assess its toxicity and determine if D. melanogaster would be a good model organism for nanotoxicology studies. Comparison of developmental progression amongst groups of flies ingesting different Ag NP concentrations (0.05%/~90 ppm-5.0%/~9000 ppm, revealed that hatch rates were unaffected, but that larval progression was impeded at any dosage of Ag NP. At 0.3% Ag NP an approximate LD50 was observed. Additionally, a distinctive phenotype was observed among emergent adults (F1 generation that arose from larvae exposed to Ag NP which included reduced body pigmentation accompanied by shortened life span and abnormal climbing behavior. The phenotype prompted speculation that Ag NPs may affect the dopamine and/or the stress response pathway(s.

  19. Photocatalytic decomposition of diclofenac potassium using silver-modified TiO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Cavalheiro, A.A. [Depto de Quimica - Instituto de Biociencias - UNESP, Distrito de Rubiao Junior, s/n, Zip Code 18.618-000, P.O. Box 510, Botucatu, SP (Brazil)], E-mail: albecava@bol.com.br; Bruno, J.C.; Saeki, M.J.; Valente, J.P.S.; Florentino, A.O. [Depto de Quimica - Instituto de Biociencias - UNESP, Distrito de Rubiao Junior, s/n, Zip Code 18.618-000, P.O. Box 510, Botucatu, SP (Brazil)

    2008-07-31

    The effects of silver insertion on the TiO{sub 2} photocatalytic activity for the degradation of diclofenac potassium were reported here. Techniques such as X-ray diffraction, scanning electron microscopy and UV-Vis spectroscopy were used to comprehend the relation between structure and properties of the silver-modified TiO{sub 2} thin films obtained by the sol-gel method. The lattice parameters and the crystallinity of TiO{sub 2} anatase phase were affected by inserted silver, and the film thickness increased about 4 nm for each 1 wt.% of silver inserted. The degradation of diclofenac potassium and by-products reached an efficiency of 4.6 mg{sub C} W{sup -1} when the material was modified with silver. Although the first step of degradation involves only the photochemical process related to the loss of the chlorine and hydrogen atoms. This cyclization reaction leads to the formation of intermediate, which degradation is facilitated by the modified material.

  20. The co phylogeny reconstruction problem is NP-complete.

    Science.gov (United States)

    Ovadia, Y; Fielder, D; Conow, C; Libeskind-Hadas, R

    2011-01-01

    The co phylogeny reconstruction problem is that of finding minimum cost explanations of differences between historical associations. The problem arises in parasitology, molecular systematics, and biogeography. Existing software tools for this problem either have worst-case exponential time or use heuristics that do not guarantee optimal solutions. To date, no polynomial time optimal algorithms have been found for this problem. In this article, we prove that the problem is NP-complete, suggesting that future research on algorithms for this problem should seek better polynomial-time approximation algorithms and heuristics rather than optimal solutions.

  1. Simulation of photofission experiments at the ELI-NP facility

    International Nuclear Information System (INIS)

    Constantin, P.; Balabanski, D.L.; Cuong, P.V.

    2016-01-01

    An extensive experimental program for the study of photofission will take place at the Extreme Light Infrastructure – Nuclear Physics (ELI-NP) facility, where different actinide targets will be exposed to a brilliant gamma beam to produce fission fragments. We report on the implementation within the Geant4 simulation toolkit of the photofission process, of related background processes, and of extended ionic charge parameterization. These developments are used to evaluate the production rates of photofission fragments and their release efficiency from the actinide targets.

  2. Spin isovector giant resonances in (n,p) reactions

    International Nuclear Information System (INIS)

    Spicer, B.M.

    1997-01-01

    The present status of the study of spin-flip isovector giant resonances, using the (n,p) charge exchange reaction, is reviewed. After a brief history of the discovery of these giant resonances, a critical appraisal of the interpretation of the data in terms of giant resonances is given, along with some of the theoretical advances that impact on the interpretation of these data. A sampling of the results obtained for typical targets is given, followed by the interpretation of these results. A brief statement is made concerning the way forward in experimental technique for nuclear structure research using charge exchange reactions

  3. NP-hardness of the cluster minimization problem revisited

    Science.gov (United States)

    Adib, Artur B.

    2005-10-01

    The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested.

  4. NP-hardness of the cluster minimization problem revisited

    International Nuclear Information System (INIS)

    Adib, Artur B

    2005-01-01

    The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested

  5. NP-hardness of the cluster minimization problem revisited

    Energy Technology Data Exchange (ETDEWEB)

    Adib, Artur B [Physics Department, Brown University, Providence, RI 02912 (United States)

    2005-10-07

    The computational complexity of the 'cluster minimization problem' is revisited (Wille and Vennik 1985 J. Phys. A: Math. Gen. 18 L419). It is argued that the original NP-hardness proof does not apply to pairwise potentials of physical interest, such as those that depend on the geometric distance between the particles. A geometric analogue of the original problem is formulated, and a new proof for such potentials is provided by polynomial time transformation from the independent set problem for unit disk graphs. Limitations of this formulation are pointed out, and new subproblems that bear more direct consequences to the numerical study of clusters are suggested.

  6. Simulation of photofission experiments at the ELI-NP facility

    Energy Technology Data Exchange (ETDEWEB)

    Constantin, P., E-mail: paul.constantin@eli-np.ro [Extreme Light Infrastructure – Nuclear Physics, “Horia Hulubei” National Institute for Physics and Nuclear Engineering, Str. Reactorului 30, 077125 Bucharest Magurele (Romania); Balabanski, D.L. [Extreme Light Infrastructure – Nuclear Physics, “Horia Hulubei” National Institute for Physics and Nuclear Engineering, Str. Reactorului 30, 077125 Bucharest Magurele (Romania); Cuong, P.V. [Centre of Nuclear Physics, Institute of Physics, Vietnam Academy of Science and Technology, Hanoi (Viet Nam)

    2016-04-01

    An extensive experimental program for the study of photofission will take place at the Extreme Light Infrastructure – Nuclear Physics (ELI-NP) facility, where different actinide targets will be exposed to a brilliant gamma beam to produce fission fragments. We report on the implementation within the Geant4 simulation toolkit of the photofission process, of related background processes, and of extended ionic charge parameterization. These developments are used to evaluate the production rates of photofission fragments and their release efficiency from the actinide targets.

  7. Silver loaded WO{sub 3-x}/TiO{sub 2} composite multifunctional thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dunnill, Charles W.; Noimark, Sacha; Parkin, Ivan P., E-mail: I.P.Parkin@ucl.ac.uk

    2012-06-30

    Multifunctional WO{sub 3-x}-TiO{sub 2} composite thin films have been prepared by sol-gel synthesis and shown to be good visible light photocatalysts whilst retaining a desirable underlying blue colouration. The WO{sub 3-x}-TiO{sub 2} composite thin films were further enhanced using silver nanoparticles synthesised in-situ on the surface from the photo-degradation of silver nitrate solution. Thin films were characterised using X-ray diffraction, Raman, Scanning electron microscopy and UV-visible spectroscopy and shown to photo degrade stearic acid, using white light {lambda} = 420-800 nm. - Highlights: Black-Right-Pointing-Pointer WO{sub 3-X} TiO{sub 2} composite thin films were synthesised by sol-gel methods. Black-Right-Pointing-Pointer Blue tinted glass is desirable for the value added glass industry. Black-Right-Pointing-Pointer Silver nanoparticle island formation enhances the activity of the films. Black-Right-Pointing-Pointer Blue tinted 'value added' coated glass is now possible.

  8. Opportunity's Surroundings on Sol 1798 (Polar)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 180-degree view of the rover's surroundings during the 1,798th Martian day, or sol, of Opportunity's surface mission (Feb. 13, 2009). North is on top. This view is presented as a polar projection with geometric seam correction. The rover had driven 111 meters (364 feet) southward on the preceding sol. Tracks from that drive recede northward in this view. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

  9. View Ahead After Spirit's Sol 1861 Drive

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images combined into this 210-degree view of the rover's surroundings during the 1,861st to 1,863rd Martian days, or sols, of Spirit's surface mission (March 28 to 30, 2009). The center of the scene is toward the south-southwest. East is on the left. West-northwest is on the right. The rover had driven 22.7 meters (74 feet) southwestward on Sol 1861 before beginning to take the frames in this view. The drive brought Spirit past the northwestern corner of Home Plate. In this view, the western edge of Home Plate is on the portion of the horizon farthest to the left. A mound in middle distance near the center of the view is called 'Tsiolkovsky' and is about 40 meters (about 130 feet) from the rover's position. This view is presented as a cylindrical projection with geometric seam correction.

  10. Opportunity's Surroundings After Sol 1820 Drive (Polar)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). This view is presented as a polar projection with geometric seam correction. North is at the top. The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

  11. Opportunity's Surroundings on Sol 1798 (Vertical)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this 180-degree view of the rover's surroundings during the 1,798th Martian day, or sol, of Opportunity's surface mission (Feb. 13, 2009). North is on top. This view is presented as a vertical projection with geometric seam correction. The rover had driven 111 meters (364 feet) southward on the preceding sol. Tracks from that drive recede northward in this view. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock.

  12. Impediment to Spirit Drive on Sol 1806

    Science.gov (United States)

    2009-01-01

    The hazard avoidance camera on the front of NASA's Mars Exploration Rover Spirit took this image after a drive by Spirit on the 1,806th Martian day, or sol, (January 31, 2009) of Spirit's mission on the surface of Mars. The wheel at the bottom right of the image is Spirit's right-front wheel. Because that wheel no longer turns, Spirit drives backwards dragging that wheel. The drive on Sol 1806 covered about 30 centimeters (1 foot). The rover team had planned a longer drive, but Spirit stopped short, apparently from the right front wheel encountering the partially buried rock visible next to that wheel. The hazard avoidance cameras on the front and back of the rover provide wide-angle views. The hill on the horizon in the right half of this image is Husband Hill. Spirit reached the summit of Husband Hill in 2005.

  13. Opportunity's Surroundings After Sol 1820 Drive (Vertical)

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). This view is presented as a vertical projection with geometric seam correction. North is at the top. The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock.

  14. Opportunity's Surroundings After Sol 1820 Drive

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). South is at the center; north at both ends. The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock. This view is presented as a cylindrical projection with geometric seam correction.

  15. Phoenix Robotic Arm's Workspace After 90 Sols

    Science.gov (United States)

    2008-01-01

    During the first 90 Martian days, or sols, after its May 25, 2008, landing on an arctic plain of Mars, NASA's Phoenix Mars Lander dug several trenches in the workspace reachable with the lander's robotic arm. The lander's Surface Stereo Imager camera recorded this view of the workspace on Sol 90, early afternoon local Mars time (overnight Aug. 25 to Aug. 26, 2008). The shadow of the the camera itself, atop its mast, is just left of the center of the image and roughly a third of a meter (one foot) wide. The workspace is on the north side of the lander. The trench just to the right of center is called 'Neverland.' The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  16. Spirit Near 'Stapledon' on Sol 1802

    Science.gov (United States)

    2009-01-01

    NASA Mars Exploration Rover Spirit used its navigation camera for the images assembled into this full-circle view of the rover's surroundings during the 1,802nd Martian day, or sol, (January 26, 2009) of Spirit's mission on the surface of Mars. South is at the center; north is at both ends. Spirit had driven down off the low plateau called 'Home Plate' on Sol 1782 (January 6, 2009) after spending 12 months on a north-facing slope on the northern edge of Home Plate. The position on the slope (at about the 9-o'clock position in this view) tilted Spirit's solar panels toward the sun, enabling the rover to generate enough electricity to survive its third Martian winter. Tracks at about the 11-o'clock position of this panorama can be seen leading back to that 'Winter Haven 3' site from the Sol 1802 position about 10 meters (33 feet) away. For scale, the distance between the parallel wheel tracks is about one meter (40 inches). Where the receding tracks bend to the left, a circular pattern resulted from Spirit turning in place at a soil target informally named 'Stapledon' after William Olaf Stapledon, a British philosopher and science-fiction author who lived from 1886 to 1950. Scientists on the rover team suspected that the soil in that area might have a high concentration of silica, resembling a high-silica soil patch discovered east of Home Plate in 2007. Bright material visible in the track furthest to the right was examined with Spirit's alpha partical X-ray spectrometer and found, indeed, to be rich in silica. The team laid plans to drive Spirit from this Sol 1802 location back up onto Home Plate, then southward for the rover's summer field season. This view is presented as a cylindrical projection with geometric seam correction.

  17. Spirit Near 'Stapledon' on Sol 1802 (Vertical)

    Science.gov (United States)

    2009-01-01

    NASA Mars Exploration Rover Spirit used its navigation camera for the images assembled into this full-circle view of the rover's surroundings during the 1,802nd Martian day, or sol, (January 26, 2009) of Spirit's mission on the surface of Mars. North is at the top. This view is presented as a vertical projection with geometric seam correction. Spirit had driven down off the low plateau called 'Home Plate' on Sol 1782 (January 6, 2009) after spending 12 months on a north-facing slope on the northern edge of Home Plate. The position on the slope (at about the 9-o'clock position in this view) tilted Spirit's solar panels toward the sun, enabling the rover to generate enough electricity to survive its third Martian winter. Tracks at about the 11-o'clock position of this panorama can be seen leading back to that 'Winter Haven 3' site from the Sol 1802 position about 10 meters (33 feet) away. For scale, the distance between the parallel wheel tracks is about one meter (40 inches). Where the receding tracks bend to the left, a circular pattern resulted from Spirit turning in place at a soil target informally named 'Stapledon' after William Olaf Stapledon, a British philosopher and science-fiction author who lived from 1886 to 1950. Scientists on the rover team suspected that the soil in that area might have a high concentration of silica, resembling a high-silica soil patch discovered east of Home Plate in 2007. Bright material visible in the track furthest to the right was examined with Spirit's alpha partical X-ray spectrometer and found, indeed, to be rich in silica. The team laid plans to drive Spirit from this Sol 1802 location back up onto Home Plate, then southward for the rover's summer field season.

  18. Spirit Near 'Stapledon' on Sol 1802 (Polar)

    Science.gov (United States)

    2009-01-01

    NASA Mars Exploration Rover Spirit used its navigation camera for the images assembled into this full-circle view of the rover's surroundings during the 1,802nd Martian day, or sol, (January 26, 2009) of Spirit's mission on the surface of Mars. North is at the top. This view is presented as a polar projection with geometric seam correction. Spirit had driven down off the low plateau called 'Home Plate' on Sol 1782 (January 6, 2009) after spending 12 months on a north-facing slope on the northern edge of Home Plate. The position on the slope (at about the 9-o'clock position in this view) tilted Spirit's solar panels toward the sun, enabling the rover to generate enough electricity to survive its third Martian winter. Tracks at about the 11-o'clock position of this panorama can be seen leading back to that 'Winter Haven 3' site from the Sol 1802 position about 10 meters (33 feet) away. For scale, the distance between the parallel wheel tracks is about one meter (40 inches). Where the receding tracks bend to the left, a circular pattern resulted from Spirit turning in place at a soil target informally named 'Stapledon' after William Olaf Stapledon, a British philosopher and science-fiction author who lived from 1886 to 1950. Scientists on the rover team suspected that the soil in that area might have a high concentration of silica, resembling a high-silica soil patch discovered east of Home Plate in 2007. Bright material visible in the track furthest to the right was examined with Spirit's alpha partical X-ray spectrometer and found, indeed, to be rich in silica. The team laid plans to drive Spirit from this Sol 1802 location back up onto Home Plate, then southward for the rover's summer field season.

  19. Ring-Resonator/Sol-Gel Interferometric Immunosensor

    Science.gov (United States)

    Bearman, Gregory; Cohen, David

    2007-01-01

    A proposed biosensing system would be based on a combination of (1) a sensing volume containing antibodies immobilized in a sol-gel matrix and (2) an optical interferometer having a ring resonator configuration. The antibodies would be specific to an antigen species that one seeks to detect. In the ring resonator of the proposed system, light would make multiple passes through the sensing volume, affording greater interaction length and, hence, greater antibody- detection sensitivity.

  20. Whirlwind Drama During Spirit's 496th Sol

    Science.gov (United States)

    2005-01-01

    This movie clip shows a dust devil growing in size and blowing across the plain inside Mars' Gusev Crater. The clip consists of frames taken by the navigation camera on NASA's Mars Exploration Rover Spirit during the morning of the rover's 496th martian day, or sol (May 26, 2005). Contrast has been enhanced for anything in the images that changes from frame to frame, that is, for the dust moved by wind.

  1. Transparent Hydrophobic Coating by Sol Gel Method

    International Nuclear Information System (INIS)

    Mohd Hamzah Harun; Nik Ghazali Nik Salleh; Mahathir Mohamed; Mohd Sofian Alias

    2016-01-01

    Transparent hydrophobic coating of inorganic based tetra orthosilicate (TEOS) was prepared by sol gel method by varying fluoroalkylsilane (FAS) content which works as hydrophobic agent. Surface contact angle, transmittance degree and surface morphology were characterized for each sample. All samples show good transparency which was confirmed by UV visible spectroscopy. The hydrophobicity obtained increases with FAS content indicates that FAS is best candidate to induce hydrophobicity for inorganic coating. (author)

  2. CpG + CpNpG Analysis of Protein-Coding Sequences from Tomato

    DEFF Research Database (Denmark)

    Hobolth, Asger; Nielsen, Rasmus; Wang, Ying

    2006-01-01

    We develop codon-based models for simultaneously inferring the mutational effects of CpG and CpNpG methylation in coding regions. In a data set of 369 tomato genes, we show that there is very little effect of CpNpG methylation but a strong effect of CpG methylation affecting almost all genes. We...... further show that the CpNpG and CpG effects are largely uncorrelated. Our results suggest different roles of CpG and CpNpG methylation, with CpNpG methylation possibly playing a specialized role in defense against transposons and RNA viruses....

  3. Sol-gel preparation of Ag-silica nanocomposite with high electrical conductivity

    Science.gov (United States)

    Ma, Zhijun; Jiang, Yuwei; Xiao, Huisi; Jiang, Bofan; Zhang, Hao; Peng, Mingying; Dong, Guoping; Yu, Xiang; Yang, Jian

    2018-04-01

    Sol-gel derived noble-metal-silica nanocomposites are very useful in many applications. Due to relatively low price, higher conductivity, and higher chemical stability of silver (Ag) compared with copper (Cu), Ag-silica has gained much more research interest. However, it remains a significant challenge to realize high loading of Ag content in sol-gel Ag-silica composite with high structural controllability and nanoparticles' dispersity. Different from previous works by using multifunctional silicon alkoxide to anchor metal ions, here we report the synthesis of Ag-silica nanocomposite with high loading of Ag nanoparticles by employing acetonitrile bi-functionally as solvent and metal ions stabilizer. The electrical conductivity of the Ag-silica nanocomposite reached higher than 6800 S/cm. In addition, the Ag-silica nanocomposite could simultaneously possess high electrical conductivity and positive conductivity-temperature coefficient by properly controlling the loading content of Ag. Such behavior is potentially advantageous for high-temperature devices (like phosphoric acid fuel cells) and inhibiting the thermal-induced increase of devices' internal resistance. The strategy proposed here is also compatible with block-copolymer directed self-assembly of mesoporous material, spin-coating of film and electrospinning of nanofiber, making it more charming in various practical applications.

  4. Mechanism of silver nanoparticles action on insect pigmentation reveals intervention of copper homeostasis.

    Directory of Open Access Journals (Sweden)

    Najealicka Armstrong

    Full Text Available Silver nanoparticles (AgNPs, like almost all nanoparticles, are potentially toxic beyond a certain concentration because the survival of the organism is compromised due to scores of pathophysiological abnormalities past that concentration. However, the mechanism of AgNP toxicity remains undetermined. Instead of applying a toxic dose, we attempted to monitor the effects of AgNPs at a nonlethal concentration on wild type Drosophila melanogaster by exposing them throughout their development. All adult flies raised in AgNP doped food showed that up to 50 mg/L concentration AgNP has no negative influence on median survival; however, these flies appeared uniformly lighter in body color due to the loss of melanin pigments in their cuticle. Additionally, fertility and vertical movement ability were compromised due to AgNP feeding. Determination of the amount of free ionic silver (Ag(+ led us to claim that the observed biological effects have resulted from the AgNPs and not from Ag(+. Biochemical analysis suggests that the activity of copper dependent enzymes, namely tyrosinase and Cu-Zn superoxide dismutase, are decreased significantly following the consumption of AgNPs, despite the constant level of copper present in the tissue. Consequently, we propose a mechanism whereby consumption of excess AgNPs in association with membrane bound copper transporter proteins cause sequestration of copper, thus creating a condition that resembles copper starvation. This model also explains the cuticular demelanization effect resulting from AgNP since tyrosinase activity is essential for melanin biosynthesis. Finally, we claim that Drosophila, an established genetic model system, can be well utilized for further understanding of the biological effects of nanoparticles.

  5. Sol-Gel Chemistry for Carbon Dots.

    Science.gov (United States)

    Malfatti, Luca; Innocenzi, Plinio

    2018-03-14

    Carbon dots are an emerging class of carbon-based nanostructures produced by low-cost raw materials which exhibit a widely-tunable photoluminescence and a high quantum yield. The potential of these nanomaterials as a substitute of semiconductor quantum dots in optoelectronics and biomedicine is very high, however they need a customized chemistry to be integrated in host-guest systems or functionalized in core-shell structures. This review is focused on recent advances of the sol-gel chemistry applied to the C-dots technology. The surface modification, the fine tailoring of the chemical composition and the embedding into a complex nanostructured material are the main targets of combining sol-gel processing with C-dots chemistry. In addition, the synergistic effect of the sol-gel precursor combined with the C-dots contribute to modify the intrinsic chemo-physical properties of the dots, empowering the emission efficiency or enabling the tuning of the photoluminescence over a wide range of the visible spectrum. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Opportunity's Surroundings on Sol 1687 (Stereo)

    Science.gov (United States)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11739 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11739 NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this stereo, 360-degree view of the rover's surroundings on the 1,687th Martian day, or sol, of its surface mission (Oct. 22, 2008). The view appears three-dimensional when viewed through red-blue glasses. Opportunity had driven 133 meters (436 feet) that sol, crossing sand ripples up to about 10 centimeters (4 inches) tall. The tracks visible in the foreground are in the east-northeast direction. Opportunity's position on Sol 1687 was about 300 meters southwest of Victoria Crater. The rover was beginning a long trek toward a much larger crater, Endeavour, about 12 kilometers (7 miles) to the southeast. This panorama combines right-eye and left-eye views presented as cylindrical-perspective projections with geometric seam correction.

  7. Sol-gel bonding of silicon wafers

    International Nuclear Information System (INIS)

    Barbe, C.J.; Cassidy, D.J.; Triani, G.; Latella, B.A.; Mitchell, D.R.G.; Finnie, K.S.; Bartlett, J.R.; Woolfrey, J.L.; Collins, G.A.

    2005-01-01

    Low temperature bonding of silicon wafers was achieved using sol-gel technology. The initial sol-gel chemistry of the coating solution was found to influence the mechanical properties of the resulting bonds. More precisely, the influence of parameters such as the alkoxide concentration, water-to-alkoxide molar ratio, pH, and solution aging on the final bond morphologies and interfacial fracture energy was studied. The thickness and density of the sol-gel coating were characterised using ellipsometry. The corresponding bonded specimens were investigated using attenuated total reflectance Fourier transformed infrared spectroscopy to monitor their chemical composition, infrared imaging to control bond integrity, and cross-sectional transmission electron microscopy to study their microstructure. Their interfacial fracture energy was measured using microindentation. An optimum water-to-alkoxide molar ratio of 10 and hydrolysis water at pH = 2 were found. Such conditions led to relatively dense films (> 90%), resulting in bonds with a fracture energy of 3.5 J/m 2 , significantly higher than those obtained using classical hydrophilic bonding (typically 1.5-2.5 J/m 2 ). Ageing of the coating solution was found to decrease the bond strength

  8. Sol-Gel Manufactured Energetic Materials

    Science.gov (United States)

    Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

    2005-05-17

    Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

  9. Sol-gel growth of vanadium dioxide

    International Nuclear Information System (INIS)

    Speck, K.R.

    1990-01-01

    This thesis examines the chemical reactivity of vanadium (IV) tetrakis(t-butoxide) as a precursor for the sol-gel synthesis of vanadium dioxide. Hydrolysis and condensation of the alkoxide was studied by FTIR spectroscopy. Chemical modification of the vanadium tetraalkoxide by alcohol interchange was studied using 51 V NMR and FTIR. Vanadium dioxide thin films and powders were made from vanadium tetrakis(t-butoxide) by standard sol-gel techniques. Post-deposition heating under nitrogen was necessary to transform amorphous gels into vanadium dioxide. Crystallization of films and powders was studied by FTIR, DSC, TGA, and XRD. Gel-derived vanadium dioxide films undergo a reversible semiconductor-to-metal phase transition near 68C, exhibiting characteristic resistive and spectral changes. The electrical resistance decreased by two to three orders of magnitude and the infrared transmission sharply dropped as the material was cycled through this thermally induced phase transition. The sol-gel method was also used to make doped vanadium dioxide films. Films were doped with tungsten and molybdenum ions to effectively lower the temperature at which the transition occurs

  10. The ELI–NP facility for nuclear physics

    International Nuclear Information System (INIS)

    Ur, C.A.; Balabanski, D.; Cata-Danil, G.; Gales, S.; Morjan, I.; Tesileanu, O.; Ursescu, D.; Ursu, I.; Zamfir, N.V.

    2015-01-01

    Extreme Light Infrastructure–Nuclear Physics (ELI–NP) is aiming to use extreme electromagnetic fields for nuclear physics research. The facility, currently under construction at Magurele–Bucharest, will comprise a high power laser system and a very brilliant gamma beam system. The technology involved in the construction of both systems is at the limits of the present-day’s technological capabilities. The high power laser system will consist of two 10 PW lasers and it will produce intensities of up to 10 23 –10 24 W/cm 2 . The gamma beam, produced via Compton backscattering of a laser beam on a relativistic electron beam, will be characterized by a narrow bandwidth (<0.5%) and tunable energy of up to almost 20 MeV. The research program of the facility covers a broad range of key topics in frontier fundamental physics and new nuclear physics. A particular attention is given to the development of innovative applications. In the present paper an overview of the project status and the overall performance characteristics of the main research equipment will be given. The main fundamental physics and applied research topics proposed to be studied at ELI–NP will also be briefly reviewed

  11. Mutation of environmental mycobacteria to resist silver nanoparticles also confers resistance to a common antibiotic.

    Science.gov (United States)

    Larimer, Curtis; Islam, Mohammad Shyful; Ojha, Anil; Nettleship, Ian

    2014-08-01

    Non-tuberculous mycobacteria are a threat to human health, gaining entry to the body through contaminated water systems, where they form persistent biofilms despite extensive attempts at disinfection. Silver is a natural antibacterial agent and in nanoparticle form activity is increased by a high surface area. Silver nanoparticles (AgNPs) have been used as alternative disinfectants in circulating water systems, washing machines and even clothing. However, nanoparticles, like any other antibiotic that has a pervasive durable presence, carry the risk of creating a resistant population. In this study Mycobacterium smegmatis strain mc(2)155 was cultured in AgNP enriched agar such that only a small population survived. Surviving cultures were isolated and re-exposed to AgNPs and AgNO3 and resistance to silver was compared to a negative control. After only a single exposure, mutant M. smegmatis populations were resistant to AgNPs and AgNO3. Further, the silver resistant mutants were exposed to antibiotics to determine if general resistance had been conferred. The minimum inhibitory concentration of isoniazid was four times higher for silver resistant mutants than for strain mc(2)155. However, core resistance was not conferred to other toxic metal ions. The mutants had lower resistance to CuSO4 and ZnSO4 than the mc(2)155 strain.

  12. Sol-gel processing to form doped sol-gel monoliths inside hollow core optical fiber and sol-gel core fiber devices made thereby

    Science.gov (United States)

    Shaw, Harry C. (Inventor); Ott, Melanie N. (Inventor); Manuel, Michele V. (Inventor)

    2002-01-01

    A process of fabricating a fiber device includes providing a hollow core fiber, and forming a sol-gel material inside the hollow core fiber. The hollow core fiber is preferably an optical fiber, and the sol-gel material is doped with a dopant. Devices made in this manner includes a wide variety of sensors.

  13. Antibacterial and Cytotoxicity Studies of Silver Nanoparticles Synthesized by Endophytic Fusarium solani Isolated from Withania somnifera (L.

    Directory of Open Access Journals (Sweden)

    Smitha Vijayan

    2016-11-01

    Full Text Available The present study establish extracellular production of silver nanoparticles (AgNP using Fusarium solani, from medicinal plant Withania somnifera (L. (ashwagandha and it’s antibacterial and cytotoxicity effects. Biological- AgNP (Bio- AgNP were synthesized by using fungal cell free extract and characterized by SEM, TEM, UV spectroscopy, XRD, FTIR and AFM analysis.  Antibacterial properties were assayed by well diffusion and cytotoxicity by RBC lysis test and MTT assay respectively. X- ray diffraction and microscopic analysis revealed the well dispersed and crystalline nature of spherical nanoparticles with a calculated size ranging from 10 - 50 nm. The Bio-AgNP exhibited significant antibacterial properties in a range of 50-100 µgml-1 against the selected clinical pathogens Escherichia coli,Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Klebsiella pneumoniae. The observed hemolysis of 3.906 % at 50 µg ml-1   suggested the safe therapeutic application of Bio - AgNP. MTT assay revealed that at the suggeseted concentration 69 % of cells are viable. These outcomes are extremely encouraging to utilize Bio-AgNP as a medication. Exploiting the endophytic organisms from therapeutic plants for improvement of nanomaterial is a uninvestigated and relatively novel territory. This may improve the likelihood in future to push the limit ahead in nanomedicine.

  14. Sol-gel synthesis of hydroxyapatite; Sintese de hidroxiapatita via sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Zupanski, M.D.; Lucena, M.P.P.; Bergmann, C.P., E-mail: michelledunin@yahoo.com.b [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

    2010-07-01

    Hydroxyapatite (HAp) has been established as the calcium phosphate based compound with most applications in the biological field. Among the numerous techniques for synthesis of HAp, the sol-gel processing route affords great control over purity and formed phases using low processing temperatures. In addition, the sol-gel approach offers an option for homogeneous HAp coating on metal substrates, as well as the ability to generate nanocrystalline powders. In this work, the sol-gel synthesis of HAp was investigated employing triethyl phosphate and calcium nitrate tetrahydrate as phosphorous and calcium precursors, respectively. The aging effect on phase composition and powder morphology of the final product was studied in terms of temperature and aging time. The powders were studied by using X-ray diffraction, Fourier transform infrared spectroscopy, particle size distribution by laser diffraction and scanning electron microscopy. (author)

  15. Ionogel Electrolytes through Sol-Gel Processing

    Science.gov (United States)

    Horowitz, Ariel I.

    Electrical energy needs have intensified due to the ubiquity of personal electronics, the decarbonization of energy services through electrification, and the use of intermittent renewable energy sources. Despite developments in mechanical and thermal methods, electrochemical technologies are the most convenient and effective means of storing electrical energy. These technologies include both electrochemical cells, commonly called batteries, and electrochemical double-layer capacitors, or "supercapacitors", which store energy electrostatically. Both device types require an ion-conducting electrolyte. Current devices use solutions of complex salts in organic solvents, leading to both toxicity and flammability concerns. These drawbacks can be avoided by replacing conventional electrolytes with room-temperature molten salts, known as ionic liquids (ILs). ILs are non-volatile, non-flammable, and offer high conductivity and good electrochemical stability. Device mass can be reduced by combining ILs with a solid scaffold material to form an "ionogel," further improving performance metrics. In this work, sol-gel chemistry is explored as a means of forming ionogel electrolytes. Sol-gel chemistry is a solution-based, industrially-relevant, well-studied technique by which solids such as silica can be formed in situ. Previous works used a simple acid-catalyzed sol-gel reaction to create brittle, glassy ionogels. Here, both the range of products that can be accomplished through sol-gel processing and the understanding of interactions between ILs and the sol-gel reaction network are greatly expanded. This work introduces novel ionogel materials, including soft and compliant silica-supported ionogels and PDMS-supported ionogels. The impacts of the reactive formulation, IL identity, and casting time are detailed. It is demonstrated that variations in formulation can lead to rapid gelation and open pore structures in the silica scaffold or slow gelation and more dense silica

  16. Potential for photocatalytic degradation of the potassic diclofenac using scandium and silver modified titanium dioxide thin films

    International Nuclear Information System (INIS)

    Ciola, R.A.; Oliveira, C.T.; Lopes, S.A.; Cavalheiro, A.A.

    2011-01-01

    The potential for photocatalytic degradation of the potassic diclofenac drug was investigated using titanium dioxide thin films modified with two modifier types, scandium and silver, both prepared by Sol-Gel method. It was demonstrated by UVVis spectroscopy analysis of the solutions containing the drug, under UV-A light irradiation that the degradation efficiency of the titanium dioxide photocatalyst is dependent of the semiconductor nature and that the scandium accelerates the first step of the degradation when compared to the silver. This result seems to be related to the redox potential of the electron-hole pair, once the scandium modifying sample generates a p type semiconductor that reduces the band gap. The extra holes attract more strongly the chorine ion present in diclofenac and leading to the releasing more easily. However, after the first byproducts degradation the following steps are not facilitated, making the silver modifying more advantageous. (author)

  17. Ionizing radiation effect on central venous catheters (CVC) of polyurethane coatings with silver nanoparticles; Efeito da radiacao ionizante nos revestimentos de cateteres venosos centrais (CVC) de poliuretano com nanoparticulas de prata

    Energy Technology Data Exchange (ETDEWEB)

    Heilman, Sonia; Silva, Leonardo G.A., E-mail: sheilman@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Hewer, Thiago L.R.; Souza, Michele L. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Quimica

    2015-07-01

    The present work aimed to study the use of ionizing radiation for coating of silver nanoparticles on central polyurethane catheters, providing reduction of infections associated with contamination of catheters introduced into the bloodstream. Silver nanoparticles have physical, chemical and biological properties only when compared to metal on a macroscopic scale, and have been used in the medical field because of its remarkable antimicrobial activity. Titanium dioxide nanoparticles obtained by the sol gel method were used as the coating catheters for subsequent impregnation of silver nanoparticles with ionizing radiation at doses of 25 and 50 kGy. A Raman spectrometry was used to identify the polymorph of titanium oxide, rutile. In trials with (ICP OES) were evaluated amounts of titanium and silver coated catheters in titanium oxide and silver.(author)

  18. Bioactive materials for biomedical applications using sol-gel technology

    International Nuclear Information System (INIS)

    Gupta, Radha; Kumar, Ashok

    2008-01-01

    This review paper focuses on the sol-gel technology that has been applied in many of the potential research areas and highlights the importance of sol-gel technology for preparing bioactive materials for biomedical applications. The versatility of sol-gel chemistry enables us to manipulate the characteristics of material required for particular applications. Sol-gel derived materials have proved to be good biomaterials for coating films and for the construction of super-paramagnetic nanoparticles, bioactive glasses and fiberoptic applicators for various biomedical applications. The introduction of the sol-gel route in a conventional method of preparing implants improves the mechanical strength, biocompatibility and bioactivity of scaffolds and prevents corrosion of metallic implants. The use of organically modified silanes (ORMOSILS) yields flexible and bioactive materials for soft and hard tissue replacement. A novel approach of nitric-oxide-releasing sol-gels as antibacterial coatings for reducing the infection around orthopedic implants has also been discussed

  19. Synthesis and characterization of silver doped hydroxyapatite nanocomposite coatings and evaluation of their antibacterial and corrosion resistance properties in simulated body fluid

    International Nuclear Information System (INIS)

    Mirzaee, Majid; Vaezi, Mohammadreza; Palizdar, Yahya

    2016-01-01

    Silver-doped hydroxyapatite (Ca 10−x Ag x (PO 4 ) 6 (OH) 2−x ) films were synthesized and deposited on anodized titanium (Ti) using electrophoretic. The influence of different silver-dopant contents (X = 0, 0.02, 0.05, 0.08 and 0.1) on the phase formation and microstructure of the powders were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), and Fourier transform infrared spectrum analysis (FT-IR). XRD analysis confirmed the formation of Hexagonal structure of hydroxyapatite (HAp) annealed at 600 °C with a small shift in the major peak position toward lower angles with adding silver. FT-IR spectroscopy disclosed the presence of the different vibrational modes matching to phosphates and hydroxyl groups and the absence of any band characteristics to silver. XPS analysis showed that 75% and 23% of silver was in the chemical states of Ag 2+ and Ag + , respectively. However, only about 2% of silver was in the Ag 0 state, resulting in the high quality of nanocomposite films. The anodization treatment improves the bond strength between the Ag doped HAp deposited layers on TiO 2 . HAp and silver doped HAp (X = 0.05) are regarded to be hydrophilic due to a large number of –OH groups on the surface. The sample with content of silver (x = 0.05) also showed excellent antimicrobial efficacy (> 99% reduction in viable cells). Electrochemical reveals the passive current densities of the HAp coated anodized Ti are lower than those of silver doped HAp coated anodized Ti, leading to a slightly lower corrosion resistance. - Highlights: • Microstructure and antibacterial properties of silver doped HAp are studied. • The nanocomposite is processed by combinations of sol gel and electrophoretic. • The optimum silver content is obtained under property evaluation.

  20. Thermal dynamics of silver clusters grown on rippled silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bhatnagar, Mukul, E-mail: mkbh10@gmail.com [FCIPT, Institute for Plasma Research, Gandhinagar, Gujarat (India); Nirma University, Ahmedabad, Gujarat (India); Ranjan, Mukesh [FCIPT, Institute for Plasma Research, Gandhinagar, Gujarat (India); Nirma University, Ahmedabad, Gujarat (India); Jolley, Kenny; Lloyd, Adam; Smith, Roger [Dept. of Mathematical Sciences, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Mukherjee, Subroto [FCIPT, Institute for Plasma Research, Gandhinagar, Gujarat (India); Nirma University, Ahmedabad, Gujarat (India)

    2017-02-15

    Highlights: • Low energy oblique angle ion bombardment forms ripple pattern on silicon surface. • The ripple patterns have wavelengths between 20 and 45 nm and correspondingly low height. • Silver nanoparticles have been deposited at an angle of 70° on patterned silicon templates. • The as-deposited np are annealed in vacuo at temperature of 573 K for a time duration of 1 h. • MD simulation is used to model the process and compare the results to the experiment. • Results show that silver clusters grow preferentially along parallel to the rippled surface. • Mobility of silver atoms depends on the site to which they are bonded on this amorphous surface. • MD simulations show contour ordered coalescence which is dependent on ripple periodicity. - Abstract: Silver nanoparticles have been deposited on silicon rippled patterned templates at an angle of incidence of 70° to the surface normal. The templates are produced by oblique incidence argon ion bombardment and as the fluence increases, the periods and heights of the structures increase. Structures with periods of 20 nm, 35 nm and 45 nm have been produced. Moderate temperature vacuum annealing shows the phenomenon of cluster coalescence following the contour of the more exposed faces of the ripple for the case of 35 nm and 45 nm but not at 20 nm where the silver aggregates into larger randomly distributed clusters. In order to understand this effect, the morphological changes of silver nanoparticles deposited on an asymmetric rippled silica surface are investigated through the use of molecular dynamics simulations for different deposition angles of incidence between 0° and 70° and annealing temperatures between 500 K and 900 K. Near to normal incidence, clusters are observed to migrate over the entire surface but for deposition at 70°, a similar patterning is observed as in the experiment. The random distribution of clusters for the periodicity ≈ of 20 nm is linked to the geometry of the silica

  1. Just add water: reproducible singly dispersed silver nanoparticle suspensions on-demand

    International Nuclear Information System (INIS)

    MacCuspie, Robert I.; Allen, Andrew J.; Martin, Matthew N.; Hackley, Vincent A.

    2013-01-01

    Silver nanoparticles (AgNPs) are of interest due to their antimicrobial attributes, which are derived from their inherent redox instability and subsequent release of silver ions. At the same time, this instability is a substantial challenge for achieving stable long-term storage for on-demand use of AgNPs. In this study, we describe and validate a “just add water” approach for achieving suspensions of principally singly dispersed AgNPs. By lyophilizing (freeze drying) the formulated AgNPs into a solid powder, or cake, water is removed thereby eliminating solution-based chemical changes. Storing under inert gas further reduces surface reactions such as oxidation. An example of how to optimize a lyophilization formulation is presented, as well as example formulations for three AgNP core sizes. This “just add water” approach enables ease of use for the researcher desiring on-demand singly dispersed AgNP suspensions from a single master batch. Implementation of this methodology will enable studies to be performed over long periods of time and across different laboratories using particles that are identical chemically and physically and available on-demand. In addition, the approach of freeze drying and on-demand reconstitution by adding water has enabled the development of AgNP reference materials with the required shelf-life stability, one of the principal objectives of this research

  2. Investigating the collector efficiency of silver nanofluids based direct absorption solar collectors

    International Nuclear Information System (INIS)

    Chen, Meijie; He, Yurong; Zhu, Jiaqi; Wen, Dongsheng

    2016-01-01

    Highlights: • An analysis coupled with Radiation transfer, Maxwell and Energy equation is developed. • Plasmonic Au and Ag nanofluids show better photo-thermal conversion properties. • Collector height and particle concentration exist optimum solutions for efficiency. - Abstract: A one-dimensional transient heat transfer analysis was carried out to analyze the effects of the Nanoparticle (NP) volume fraction, collector height, irradiation time, solar flux, and NP material on the collector efficiency. The numerical results were compared with the experimental results obtained by silver nanofluids to validate the model, and good agreement was obtained. The numerical results show that the collector efficiency increases as the collector height and NP volume fraction increase and then reaches a maximum value. An optimum collector height (∼10 mm) and particle concentration (∼0.03%) achieving a collector efficiency of 90% of the maximum efficiency can be obtained under the conditions used in the simulation. However, the collector efficiency decreases as the irradiation time increases owing to the increased heat loss. A high solar flux is desirable to maintain a high efficiency over a wide temperature range, which is beneficial for subsequent energy utilization. The modeling results also show silver and gold nanofluids obtain higher photothermal conversion efficiencies than the titanium dioxide nanofluid because their absorption spectra are similar to the solar radiation spectrum.

  3. Developing the procedure of modifying the denture soft liner by silver nanoparticles.

    Science.gov (United States)

    Chladek, Grzegorz; Barszczewska-Rybarek, Izabela; Lukaszczyk, Jan

    2012-01-01

    Colonization of denture soft lining materials by fungi and denture plaque leads to infections of mucosa. Microorganisms such as Candida albicans colonize not only the surface of the soft liners, but they also penetrate inside those materials. Therefore the use of common disinfectants, e.g., surface active cleaners, is not a perfect solution for keeping a proper hygiene of soft linings. Modifying soft lining by silver nanoparticles (AgNP) seems to be a right way to overcome those problems. The procedure of modifying two-component silicone material by silver nanoparticles (AgNP) is presented in the article. The solubility tests for both material components have been carried out in the first stage of examinations. On the basis of test results, a solvent has been selected, being a dispersion medium for AgNPs and both soft liner components. The effective method for evaporating a solvent from the composition has been developed. Material components with various AgNP concentrations (10, 20, 40, 80, 120 and 200 ppm) have been obtained. Cured samples of the composites have been examined by SEM to confirm the effectiveness of the procedure.

  4. Biocidal Activity of Plasma Modified Electrospun Polysulfone Mats Functionalized with Polyethyleneimine-Capped Silver Nanoparticles

    KAUST Repository

    Schiffman, Jessica D.

    2011-11-01

    The incorporation of silver nanoparticles (AgNPs) into polymeric nanofibers has attracted a great deal of attention due to the strong antimicrobial activity that the resulting fibers exhibit. However, bactericidal efficacy of AgNP-coated electrospun fibrous mats has not yet been demonstrated. In this study, polysulfone (PSf) fibers were electrospun and surface-modified using an oxygen plasma treatment, which allowed for facile irreversible deposition of cationically charged polyethyleneimine (PEI)-AgNPs via electrostatic interactions. The PSf-AgNP mats were characterized for relative silver concentration as a function of plasma treatment time using ICP-MS and changes in contact angle. Plasma treatment of 60 s was the shortest time required for maximum loss of bacteria (Escherichia coli) viability. Time-dependent bacterial cytotoxicity studies indicate that the optimized PSf-AgNP mats exhibit a high level of inactivation against both Gram negative bacteria, Escherichia coli, and Gram positive bacteria, Bacillus anthracis and Staphylococcus aureus. © 2011 American Chemical Society.

  5. Combined bactericidal activity of silver nanoparticles and hexadecylpyridinium salicylate ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Leonardo T. [Universidade Federal de São Paulo, Laboratório de Materiais Híbridos, Departamento de Ciências Exatas e da Terra, Instituto de Ciências Ambientais, Químicas e Farmacêuticas (Brazil); Liberatore, Ana Maria A.; Koh, Ivan H. J. [Universidade Federal de São Paulo, Laboratório de Transplante Experimental de Órgãos, Departamento de Cirurgia, Escola Paulista de Medicina (Brazil); Bizeto, Marcos A.; Camilo, Fernanda F., E-mail: ffcamilo@unifesp.br [Universidade Federal de São Paulo, Laboratório de Materiais Híbridos, Departamento de Ciências Exatas e da Terra, Instituto de Ciências Ambientais, Químicas e Farmacêuticas (Brazil)

    2015-03-15

    Recently, ionic liquids have been used as dispersing agents for silver nanoparticle (AgNP) preparation. In this paper, we have shown a simple method to prepare AgNP in aqueous media using an ionic liquid called hexadecylpyridinium salicylate (HDPSal) as dispersing agent. The dispersions were produced by the chemical reduction of silver ions in aqueous media with different concentrations of HDPSal and tetrabutylammonium borohydride as reducing agent. The UV–Visible electronic spectra showed the characteristic plasmonic resonance band around 420 nm, confirming the formation of AgNPs. The TEM images confirmed the formation of spherical particles with diameters lower than 10 nm. The charge of these particles was determined by Zeta potential and they were around +50 mV, indicating that the HDP cations are surrounding the AgNPs, avoiding their agglomeration. Most of the dispersions remained stable for at least 1 month. Microbiological assays showed that the combination of AgNP with HDPSal results in wider range of antimicrobial effect.

  6. Vanadium dioxide formed by the sol-gel process

    International Nuclear Information System (INIS)

    Potember, R.S.; Speck, K.R.; Hu, H.S.

    1990-01-01

    This patent describes a process for the deposition of a crystalline vanadium dioxide thin film. It comprises: providing a solution comprising a vanadium tetraalkoxide and solvent; allowing hydrolysis and condensation reactions to progressively form a homogeneous sol from the solution, applying a coating of the sol to the substrate; allowing a gel to form from the sol on the substrate by evaporating the solvent; dehydrating the gel by heat treatment under an inert atmosphere to form the crystalline vanadium dioxide film

  7. Abstracts of International Conference on Sol-Gel Materials' 04

    International Nuclear Information System (INIS)

    2004-01-01

    International Conference on Sol-Gel Materials '04 was an important forum for discussion on problems related to sol-gel processes applied for preparation materials with special physical properties and assignment. The application of sol-gel materials as phosphors, surface coatings, sensors, waveguides, medical implants, joints etc. has been presented. Preparation conditions, methods of physical characterization as well as optimal chemical composition of such materials have been also discussed in detail

  8. Current and future possibilities of sol-gel process

    International Nuclear Information System (INIS)

    Sakka, Sumio

    2004-01-01

    The sol-gel method is characterized by the low temperature processing. Since this method starts from solutions, the product is essentially nanomaterials. So far, various kinds of microstructures, including dense, porous, hybrid, amorphous and crystalline microstructures have been realized. Accordingly, sol-gel materials cover a wide range of functions, such as optical, electronic, mechanical, chemical and bio-functions. Future perspectives of the sol-gel method are described in the article. (author)

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

    DEFF Research Database (Denmark)

    Hadrup, Niels; Lam, Henrik Rye

    2014-01-01

    Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin......, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts...... and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least...

  10. Savannah River Plant 200 Area technical manual. Part SP. Processing of Np/sup 237/ and Pu/sup 238/

    Energy Technology Data Exchange (ETDEWEB)

    Hill, A.J. (comp.)

    1963-01-03

    This manual covers the technology involved in the 200 Area process for the recovery of Np/sup 237/ from certain aqueous waste streams in the separations plants, for the recovery of NP/sup 237/ and Pu/sup 238/ from irradiated NpO/sub 2/-Al slugs and for the fabrication of NpO/sub 2/-Al slugs. The manual contains sections on the fundamental chemistry, the primary recovery of Np by ion exchange, the decontamination of Np by ion exchange, the processing of NpO/sub 2/-Al targets, the separation and purification of Np/sup 237/ and Pu/sup 238/, the finishing of Np, the preparation of NpO/sub 2/, the disposal of spent resin, and the safety aspects of the handling of hydrazine. The section on the fabrication of NpO/sub 2/-Al slugs will be added later. 76 refs., 22 figs.

  11. Functionalised Silver Nanowire Structures

    International Nuclear Information System (INIS)

    Andrew, Piers; Ilie, Adelina

    2007-01-01

    Crystalline silver nanowires 60-100 nm in diameter and tens of micrometres in length have been fabricated using a low temperature, solution synthesis technique. We explore the potential of this method to produce functional nanowire structures using two different strategies to attach active molecules to the nanowires: adsorption and displacement. Initially, as-produced silver nanowires capped with a uniaxial-growth-inducing polymer layer were functionalised by solution adsorption of a semiconducting conjugated polymer to generate fluorescent nanowire structures. The influence of nanowire surface chemistry was investigated by displacing the capping polymer with an alkanethiol self-assembled monolayer, followed by solution adsorption functionalisation. The success of molecular attachment was monitored by electron microscopy, absorption and fluorescence spectroscopy and confocal fluorescence microscopy. We examined how the optical properties of such adsorbed molecules are affected by the metallic nanowires, and observed transfer of excitation energy between dye molecules mediated by surface plasmons propagating on the nanowires. Non-contact dynamic force microscopy measurements were used to map the work-function of individual wires, revealing inhomogeneity of the polymer surface coverage

  12. Fabrication of Antibacterial Wound Dressings from Silk Fibroin and Silver Nano particles

    International Nuclear Information System (INIS)

    Uttayarat, P.; Jetawattana, S.; Suwanmala, P.; Eamsiri, J.; Pongpat, S.

    2011-06-01

    Full text: Patients with burn wounds that cover large body surface area are susceptible to infection which can lead to fatality. Wound dressings or skin grafts are needed to cover the wound during the regeneration of new skin tissue. The aim of this research is to fabricate antibacterial wound dressings from silk fibroin derived from the natural silk cocoon and silver nanoparticles (AgNPs) prepared by gamma irradiation. Fibroin mats composed of nonwoven fibers with diameter of 670± 11.5 nm were fabricated by electro spinning. Using gamma irradiation, the starting silver nitrate solution was reduced to colloidal AgNPs. The fibroin mats were coated with AgNPs at various AgNP concentration and then evaluated for their antibacterial property by disc diffusion test. The concentration of colloidal AgNP solution ≤ 1 mM was found to be as sufficient in inhibiting the growth of Pseudomonas aeruginosa and Staphylococcus aureus as commercial wound dressings embedded with silver ions. These results demonstrate that electro spun fibroin mats coated with AgNPs exhibite antibacterial property and can be further developed for the treatment of burn wounds

  13. Silver Nanoparticles Induce HePG-2 Cells Apoptosis Through ROS-Mediated Signaling Pathways

    Science.gov (United States)

    Zhu, Bing; Li, Yinghua; Lin, Zhengfang; Zhao, Mingqi; Xu, Tiantian; Wang, Changbing; Deng, Ning

    2016-04-01

    Recently, silver nanoparticles (AgNPs) have been shown to provide a novel approach to overcome tumors, especially those of hepatocarcinoma. However, the anticancer mechanism of silver nanoparticles is unclear. Thus, the purpose of this study was to estimate the effect of AgNPs on proliferation and activation of ROS-mediated signaling pathway on human hepatocellular carcinoma HePG-2 cells. A simple chemical method for preparing AgNPs with superior anticancer activity has been showed in this study. AgNPs were detected by transmission electronic microscopy (TEM) and energy dispersive X-ray (EDX). The size distribution and zeta potential of silver nanoparticles were detected by Zetasizer Nano. The average size of AgNPs (2 nm) observably increased the cellular uptake by endocytosis. AgNPs markedly inhibited the proliferation of HePG-2 cells through induction of apoptosis with caspase-3 activation and PARP cleavage. AgNPs with dose-dependent manner significantly increased the apoptotic cell population (sub-G1). Furthermore, AgNP-induced apoptosis was found dependent on the overproduction of reactive oxygen species (ROS) and affecting of MAPKs and AKT signaling and DNA damage-mediated p53 phosphorylation to advance HePG-2 cells apoptosis. Therefore, our results show that the mechanism of ROS-mediated signaling pathways may provide useful information in AgNP-induced HePG-2 cell apoptosis.

  14. Sol-gel-state of hydrated zirconium dioxide

    International Nuclear Information System (INIS)

    Karakchiev, L.G.; Lyakhov, N.Z.

    1995-01-01

    The change in viscosity and density of a system in the course of sol-gel-xerogel has been traced. The size and molecular mass of particles in sol have been determined. Initial sol is practically a monodisperse system. Gel is a spatial net of similar particles. Reversible character of sol-gel transition with a change in water content in the system suggests instability of the bond between the particles in the structure of the solid state body formed. 11 refs.; 4 figs

  15. Highly concentrated zinc oxide nanocrystals sol with strong blue emission

    International Nuclear Information System (INIS)

    Vafaee, M.; Sasani Ghamsari, M.; Radiman, S.

    2011-01-01

    Highly concentrated ZnO sol was synthesized by an improved sol-gel method. Water was used as a modifier to control the sol-gel reaction and provide a way to increase the sol concentration. Concentration of ZnO in the prepared sol is higher than from other methods. Optical absorption and photoluminescence were used to investigate optical properties of the prepared sol. FTIR test was performed to study the influence of water on the compounds of as-prepared sol. The size and morphology of ZnO nanoparticles have been studied by HRTEM. The prepared colloidal ZnO nanocrystals have narrow size distribution (5-8 nm) and showed strong blue emission. The prepared sol has enough potential for optoelectronic applications. - Research highlights: → Novel sol-gel route has been employed to prepare highly concentrated ZnO colloidal nanocrystals. → Water has been used to control the sources of emission in synthesized material. → A strong blue luminescent material has been obtained.

  16. Method of making ionic liquid mediated sol-gel sorbents

    Science.gov (United States)

    Malik, Abdul; Shearrow, Anne M.

    2017-01-31

    Ionic liquid (IL)-mediated sol-gel hybrid organic-inorganic materials present enormous potential for effective use in analytical microextraction. One obstacle to materializing this prospect arises from high viscosity of ILs significantly slowing down sol-gel reactions. A method was developed which provides phosphonium-based, pyridinium-based, and imidazolium-based IL-mediated advanced sol-gel organic-inorganic hybrid materials for capillary microextraction. Scanning electron microscopy results demonstrate that ILs can serve as porogenic agents in sol-gel reactions. IL-mediated sol-gel coatings prepared with silanol-terminated polymers provided up to 28 times higher extractions compared to analogous sol-gel coatings prepared without any IL in the sol solution. This study shows that IL-generated porous morphology alone is not enough to provide effective extraction media: careful choice of the organic polymer and the precursor with close sol-gel reactivity must be made to ensure effective chemical bonding of the organic polymer to the created sol-gel material to be able to provide the desired sorbent characteristics.

  17. Sol-gel processing with inorganic metal salt precursors

    Science.gov (United States)

    Hu, Zhong-Cheng

    2004-10-19

    Methods for sol-gel processing that generally involve mixing together an inorganic metal salt, water, and a water miscible alcohol or other organic solvent, at room temperature with a macromolecular dispersant material, such as hydroxypropyl cellulose (HPC) added. The resulting homogenous solution is incubated at a desired temperature and time to result in a desired product. The methods enable production of high quality sols and gels at lower temperatures than standard methods. The methods enable production of nanosize sols from inorganic metal salts. The methods offer sol-gel processing from inorganic metal salts.

  18. Effect of sol-age on the surface and optical properties of sol-gel derived mesoporous zirconia thin films

    Directory of Open Access Journals (Sweden)

    Manish Kumar

    2011-06-01

    Full Text Available Mesoporous ZrO2 thin films have been deposited by a modified sol-gel dip coating technique using HCl as catalyst. Effects of sol-age on the surface and on the optical properties are studied. Transmission electron micrographs of the films reveal the pore dimensions in mesoporous regime. A strong correlation in surface topography with sol-age has been observed where increase in sol-age induces a systematic enhancement in the value of root mean square roughness of the films. Optical study shows that deposited films have high transmittance and an enhancement of 5.6 times in porosity in films prepared with sol-age of 10 days with respect to that of 1 day. Band gap estimation by Tauc's plots of films is observed to 5.74 eV, which shows invariance with the sol-age.

  19. Cellular Neural Networks for NP-Hard Optimization

    Directory of Open Access Journals (Sweden)

    Mária Ercsey-Ravasz

    2009-02-01

    Full Text Available A cellular neural/nonlinear network (CNN is used for NP-hard optimization. We prove that a CNN in which the parameters of all cells can be separately controlled is the analog correspondent of a two-dimensional Ising-type (Edwards-Anderson spin-glass system. Using the properties of CNN, we show that one single operation (template always yields a local minimum of the spin-glass energy function. This way, a very fast optimization method, similar to simulated annealing, can be built. Estimating the simulation time needed on CNN-based computers, and comparing it with the time needed on normal digital computers using the simulated annealing algorithm, the results are astonishing. CNN computers could be faster than digital computers already at 10×10 lattice sizes. The local control of the template parameters was already partially realized on some of the hardwares, we think this study could further motivate their development in this direction.

  20. np Elastic-scattering experiments with polarized neutron beams

    International Nuclear Information System (INIS)

    Chalmers, J.S.; Ditzler, W.R.; Hill, D.

    1985-01-01

    Measurements of the spin transfer parameters, K/sub NN/ and K/sub LL/, at 500, 650, and 800 MeV are presented for the reaction p-vector d → n-vector pp at 0 0 . The data are useful input to the NN data base and indicate that the quasi-free charge exchange (CEX) reaction is a useful mechanism for producing neutrons with at least 40% polarization at energies as low as 500 MeV. Measurements of np elastic scattering observables C/sub LL/ and C/sub SL/ covering 35 0 to 172 0 are performed using a polarized neutron beam at 500, 650, and 800 MeV. Preliminary results are presented. 3 refs., 6 figs

  1. NP-hardness of decoding quantum error-correction codes

    Science.gov (United States)

    Hsieh, Min-Hsiu; Le Gall, François

    2011-05-01

    Although the theory of quantum error correction is intimately related to classical coding theory and, in particular, one can construct quantum error-correction codes (QECCs) from classical codes with the dual-containing property, this does not necessarily imply that the computational complexity of decoding QECCs is the same as their classical counterparts. Instead, decoding QECCs can be very much different from decoding classical codes due to the degeneracy property. Intuitively, one expects degeneracy would simplify the decoding since two different errors might not and need not be distinguished in order to correct them. However, we show that general quantum decoding problem is NP-hard regardless of the quantum codes being degenerate or nondegenerate. This finding implies that no considerably fast decoding algorithm exists for the general quantum decoding problems and suggests the existence of a quantum cryptosystem based on the hardness of decoding QECCs.

  2. NP-hardness of decoding quantum error-correction codes

    International Nuclear Information System (INIS)

    Hsieh, Min-Hsiu; Le Gall, Francois

    2011-01-01

    Although the theory of quantum error correction is intimately related to classical coding theory and, in particular, one can construct quantum error-correction codes (QECCs) from classical codes with the dual-containing property, this does not necessarily imply that the computational complexity of decoding QECCs is the same as their classical counterparts. Instead, decoding QECCs can be very much different from decoding classical codes due to the degeneracy property. Intuitively, one expects degeneracy would simplify the decoding since two different errors might not and need not be distinguished in order to correct them. However, we show that general quantum decoding problem is NP-hard regardless of the quantum codes being degenerate or nondegenerate. This finding implies that no considerably fast decoding algorithm exists for the general quantum decoding problems and suggests the existence of a quantum cryptosystem based on the hardness of decoding QECCs.

  3. Interaction of Np(4) and Pu(4) with diisoamylphosphoric acid

    International Nuclear Information System (INIS)

    Sokhina, L.P.; Rovnyj, S.I.; Goncharuk, L.V.; Sladkova, M.V.; Tyumentseva, L.M.

    1988-01-01

    Interaction of neptunium (4) and plutonium (4) with diisoamylphosphoric acid (HD) in nitric acid solutions is investigated. It is ascertained that depending on mole ratio of HD and Np(Pu) in solution three types of compounds: Me (NO 3 ) 2 D 2 , Me(NO 3 ) 2 D 2 ·2HD and Me(NO 3 ) 2 D 2 ·4HD, are formed. The solubility of neptunium (plutonium) diisoamylphosphates in nitric acid, oxalate, carbonate and organic solutions, is determined. The possibility of the compound depositions in the extraction equipment should be taken into account in the process of spent fuel regeneration, when 30% HD solutions in n-paraffins are used as extractants

  4. In situ synthesis of silver-nanoparticles/bacterial cellulose composites for slow-released antimicrobial wound dressing.

    Science.gov (United States)

    Wu, Jian; Zheng, Yudong; Song, Wenhui; Luan, Jiabin; Wen, Xiaoxiao; Wu, Zhigu; Chen, Xiaohua; Wang, Qi; Guo, Shaolin

    2014-02-15

    Bacterial cellulose has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity, which is one of critical skin-barrier functions in wound healing. To overcome such deficiency, we developed a novel method to synthesize and impregnate silver nanoparticles on to bacterial cellulose nanofibres (AgNP-BC). Uniform spherical silver nano-particles (10-30 nm) were generated and self-assembled on the surface of BC nano-fibers, forming a stable and evenly distributed Ag nanoparticles coated BC nanofiber. Such hybrid nanostructure prevented Ag nanoparticles from dropping off BC network and thus minimized the toxicity of nanoparticles. Regardless the slow Ag(+) release, AgNP-BC still exhibited significant antibacterial activities with more than 99% reductions in Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, AgNP-BC allowed attachment and growth of epidermal cells with no cytotoxicity emerged. The results demonstrated that AgNP-BC could reduce inflammation and promote wound healing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. [One-time effects of drinking mineral water and tap water enriched with silver nanoparticles on the biochemical markers of liver condition and metabolic parameters in healthy rats].

    Science.gov (United States)

    Efimenko, N V; Frolkov, V K; Kozlova, V V; Kaisinova, A S; Chalaya, E N

    2017-12-05

     The objective of the present research was to study the influence of tap water enriched with silver nanoparticles (NP) as well as that of «Krasnoarmeysky» and «Essentuki №17» mineral waters after their single administration through the oral gavage to the rats on the metabolism of carbohydrates and lipids, the biochemical markers of the liver condition, and the endocrine profile in the healthy animals.  The laboratory animals (130 male Wistar rats) were allocated to thirteen groups comprised of 10 rats each as follows: 1st group (n=10) intact animals, 2nd group (5 minutes after the administration of silver NP (n=10), 3rd group (15 minutes after the of silver NP), 4th group (60 minutes after the administration of silver NP), 5th group (n=10) (5 minutes after the introduction of the «Krasnoarmeysky» mineral water), 6th group (n=10) (15 min after the introduction of the «Krasnoarmeysky» mineral water), 7th group (n=10), (60 minutes after the introduction of the «Krasnoarmeysky» mineral water) 8th group (n=10) (5 minutes after the introduction of the «Essentuki № 17» mineral water), 9th group (n=10) (15 min after the introduction of the «Essentuki № 7» mineral water) , 10th group (n=10) (60 minutes after the introduction of the «Essentuki №17» mineral water), 11th group (n=10) (5 minutes after administration of tap water (control),12th group (n=10) (15 minutes after administration of tap water (control), and 13th (n=10) group 60 minutes after administration of tap water (control).  The study has demonstrated that the tap water enriched with silver nanoparticles similar to the mineral waters caused stress reactions that are inferior to those induced by «Essentuki №17» mineral water in terms of the magnitude; however, the effect provoked by the tap water was of longer duration. Moreover, the tap water enriched with silver nanoparticles stimulates prooxidant reactions, and inhibit the activity of antioxidant protection. Silver nanoparticles

  6. Effect of agglomeration of silver nanoparticle on nanotoxicity depression

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Eunjoo; Yi, Jongheop [Seoul National University, Seoul (Korea, Republic of); Lee, Byung-Cheun; Choi, Kyunghee [National Institute of Environmental Research, Incheon (Korea, Republic of); Kim, Younghun [Kwangwoon University, Seoul (Korea, Republic of)

    2013-02-15

    Silver nanoparticles (AgNPs) are used commercially in a variety of applications, including textiles, cosmetics, spray cleaning agents, and metal products. AgNP itself, however, is classified as an environmental hazard by Environmental Protection Agency (EPA, USA) Nanotechnology White Paper, due to its toxic, persistent and bioaccumulative characteristics when exposed to the environment. We investigated the cumulative mortality and abnormalities in Japanese medaka (Oryziaslatipes) embryos after exposure to AgNPs. Free AgNPs in solution have a high activity with respect to biological interactions regarding blocking blood flow and distribution of AgNPs into the cells from head to tail of hatched O. latipes. Interestingly, the agglomeration of AgNPs (loss of nanosized characteristics) played an important role in the environmental toxicity. The present study demonstrated that when the AgNPs were exposed in the ecosystem and then formed agglomerates, nanotoxicity was reduced.

  7. Effect of agglomeration of silver nanoparticle on nanotoxicity depression

    International Nuclear Information System (INIS)

    Bae, Eunjoo; Yi, Jongheop; Lee, Byung-Cheun; Choi, Kyunghee; Kim, Younghun

    2013-01-01

    Silver nanoparticles (AgNPs) are used commercially in a variety of applications, including textiles, cosmetics, spray cleaning agents, and metal products. AgNP itself, however, is classified as an environmental hazard by Environmental Protection Agency (EPA, USA) Nanotechnology White Paper, due to its toxic, persistent and bioaccumulative characteristics when exposed to the environment. We investigated the cumulative mortality and abnormalities in Japanese medaka (Oryziaslatipes) embryos after exposure to AgNPs. Free AgNPs in solution have a high activity with respect to biological interactions regarding blocking blood flow and distribution of AgNPs into the cells from head to tail of hatched O. latipes. Interestingly, the agglomeration of AgNPs (loss of nanosized characteristics) played an important role in the environmental toxicity. The present study demonstrated that when the AgNPs were exposed in the ecosystem and then formed agglomerates, nanotoxicity was reduced

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

    Science.gov (United States)

    Leslie, Renee M.

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

  9. Solubility and hydrolysis of Np(V) in dilute to concentrated alkaline NaCl solutions. Formation of Na-Np(V)-OH solid phases at 22 C

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, Vladimir G. [Lomonosov Moscow State Univ. (Russian Federation). Dept. of Chemistry; Fellhauer, David; Gaona, Xavier; Dardenne, Kathy; Rothe, Joerg; Altmaier, Marcus [Karlsruhe Institute of Technology (Germany). Inst. for Nuclear Waste Disposal; Kalmykov, Stepan N. [Lomonosov Moscow State Univ. (Russian Federation). Dept. of Chemistry; NRC Kurchatov Institute, Moscow (Russian Federation)

    2017-03-01

    The solubility of Np(V) was investigated at T=22±2 C in alkaline NaCl solutions of different ionic strength (0.1-5.0 M). The solid phases controlling the solubility at different -log{sub 10} m{sub H{sup +}}(pH{sub m}) and NaCl concentration were characterized by XRD, quantitative chemical analysis, SEM-EDS and XAFS (both XANES and EXAFS). Aqueous phases in equilibrium with Np(V) solids were investigated for selected samples within 8.9≤pH{sub m}≤10.3 by UV-vis/NIR absorption spectroscopy. In 0.1 M NaCl, the experimental solubility of the initial greenish NpO{sub 2}OH(am) solid phase is in good agreement with previous results obtained in NaClO{sub 4} solutions, and is consistent with model calculations for fresh NpO{sub 2}OH(am) using the thermodynamic data selection in NEA-TDB. Below pH{sub m}∝11.5 and for all NaCl concentrations studied, Np concentration in equilibrium with the solid phase remained constant during the timeframe of this study (∝2 years). This observation is in contrast to the aging of the initial NpO{sub 2}OH(am) into a more crystalline modification with the same stoichiometry, NpO{sub 2}OH(am, aged), as reported in previous studies for concentrated NaClO{sub 4} and NaCl. Instead, the greenish NpO{sub 2}OH(am) transforms into a white solid phase in those systems with [NaCl]≥1.0 M and pH{sub m}≥11.5, and into two different pinkish phases above pH{sub m}∝13.2. The solid phase transformation is accompanied by a drop in Np solubility of 0.5-2 log{sub 10}-units (depending upon NaCl concentration). XANES analyses of green, white and pink phases confirm the predominance of Np(V) in all cases. Quantitative chemical analysis shows the incorporation of Na{sup +} in the original NpO{sub 2}OH(am) material, with Na:Np ≤ 0.3 for the greenish solids and 0.8 ≤ Na:Np ≤ 1.6 for the white and pinkish phases. XRD data confirms the amorphous character of the greenish phase, whereas white and pink solids show well-defined but discrepant XRD patterns

  10. S argassum muticum-synthesized silver nanoparticles: an effective control tool against mosquito vectors and bacterial pathogens.

    Science.gov (United States)

    Madhiyazhagan, Pari; Murugan, Kadarkarai; Kumar, Arjunan Naresh; Nataraj, Thiyagarajan; Dinesh, Devakumar; Panneerselvam, Chellasamy; Subramaniam, Jayapal; Mahesh Kumar, Palanisamy; Suresh, Udaiyan; Roni, Mathath; Nicoletti, Marcello; Alarfaj, Abdullah A; Higuchi, Akon; Munusamy, Murugan A; Benelli, Giovanni

    2015-11-01

    Mosquito-borne diseases represent a deadly threat for millions of people worldwide. Furthermore, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. In this research, silver nanoparticles (AgNP) were synthesized using the aqueous extract of the seaweed Sargassum muticum. The production of AgNP was confirmed by surface plasmon resonance band illustrated in UV-vis spectrophotometry. AgNP were characterized by FTIR, SEM, EDX, and XRD analyses. AgNP were mostly spherical in shape, crystalline in nature, with face-centered cubic geometry, and mean size was 43-79 nm. Toxicity of AgNP was assessed against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. In laboratory, AgNP were highly toxic against larvae and pupae of the three mosquito species. Maximum efficacy was observed against A. stephensi larvae, with LC50 ranging from 16.156 ppm (larva I) to 28.881 ppm (pupa). In the field, a single treatment with AgNP (10 × LC50) in water storage reservoirs was effective against the three mosquito vectors, allowing complete elimination of larval populations after 72 h. In ovicidal experiments, egg hatchability was reduced by 100% after treatment with 30 ppm of AgNP. Ovideterrence assays highlighted that 10 ppm of AgNP reduced oviposition rates of more than 70% in A. aegypti, A. stephensi, and C. quinquefasciatus (OAI = -0.61, -0.63, and -0.58, respectively). Antibacterial properties of AgNP were evaluated against Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. AgNP tested at 50 ppm evoked growth inhibition zones larger than 5 mm in all tested bacteria. Overall, the chance to use S. muticum-synthesized AgNP for control of mosquito vectors seems promising since they are effective at low doses and may constitute an advantageous alternative to build newer and safer mosquito control tools. This is the first

  11. sol y playa: el caso de Tenerife

    Directory of Open Access Journals (Sweden)

    Ricardo J. Díaz Armas

    2008-01-01

    Full Text Available El turismo del vino tiene una concepción distinta en un destino masivo de sol y playa. En este caso el enoturismo convive con ese modelo turístico y es un producto complementario que favorece la diversificación en la oferta actual. El turismo del vino puede complementar la ya existente oferta turística, con lo que las regiones, turísticas y a la vez viníferas, podrían apoyarse en las experiencias y conocimiento del vino por parte del visitante y utilizarlas como hecho diferencial competitivo frente a otros destinos de sol y playa que no poseen esta particularidad. Con ello además se favorecerá el lanzamiento del producto turístico del vino, pues la demanda latente ya esta en las zonas turísticas que rodean el área vinícola. En este sentido, una vez que se descubren las motivaciones para acudir al destino Tenerife, se localiza un mercado sensible a la ruta del vino Tacoronte-Acentejo en el asentamiento turístico del Puerto de la Cruz (una de las principales zonas turísticas de Tenerife. Así, tras conocer los beneficios buscados por el visitante del Puerto de la Cruz, se ha contrastado la existencia de dos segmentos latentes que pueden ser atraídos hacia la oferta actual de la ruta del vino en Tacoronte-Acentejo, al verificar que persiguen, además del clima y el sol y playa (principales motivaciones para viajar al destino Tenerife, otros beneficios que son susceptibles de ser ofertados por la ruta del vino.

  12. Mesure de la vitesse d'infiltration des eaux dans le sol : Cas des sols ...

    African Journals Online (AJOL)

    SARAH

    30 avr. 2016 ... Pour ceux, il est nécessaire d'opter pour une agriculture moderne ... à une telle agriculture. Mots clés : mesure, vitesse, infiltration, sols, pollutions, eau, Niari, Congo .... une porosité tubulaire d'origine biologique. Toutes ces.

  13. Toxicological evaluation of nano-sized colloidal silver in experiments on mice. behavioral reactions, morphology of internals

    Directory of Open Access Journals (Sweden)

    N.V. Zaitseva

    2015-06-01

    Full Text Available The results of toxicity studies of nano-sized colloidal silver (NCC, the most widely used in medicine, food and life, are given. When evaluating safe doses of silver NP (using commercially available NCC solution stabilized with polyvinylpyrrolidone (PVP, with the size of silver NP at the range of 5-80 nm when orally administered to male mice, BALB/c mice at doses of 0.1; 1.0 and 10 mg/kg of body weight per silver different effects from the motor and orienting-exploratory activity were revealed, for the part of them the dependence on the dose of the NCC was typical. The following peculiarities were found: reduction in motor activity to reduce the frequency of activities requiring physical effort, reduction of the execution time of these actions; increasing anxiety in terms of frequency and duration of attacks of orienting-investigative activity and animals washing. Morphological examination revealed a series of tissue changes of internal organs (especially liver and spleen, to a lesser extent – kidney, heart and colon with increase of the spectrum and severity of structural changes with increasing doses of the NCC. From the combination of the data the conclusion was made that maximal ineffective dose (NOAEL of this nanomaterial at subacute oral administration is no more than 0.1 mg/kg body weight.

  14. Spirit Near 'Stapledon' on Sol 1802 (Stereo)

    Science.gov (United States)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11781 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11781 NASA Mars Exploration Rover Spirit used its navigation camera for the images assembled into this stereo, full-circle view of the rover's surroundings during the 1,802nd Martian day, or sol, (January 26, 2009) of Spirit's mission on the surface of Mars. South is at the center; north is at both ends. This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left. Spirit had driven down off the low plateau called 'Home Plate' on Sol 1782 (January 6, 2009) after spending 12 months on a north-facing slope on the northern edge of Home Plate. The position on the slope (at about the 9-o'clock position in this view) tilted Spirit's solar panels toward the sun, enabling the rover to generate enough electricity to survive its third Martian winter. Tracks at about the 11-o'clock position of this panorama can be seen leading back to that 'Winter Haven 3' site from the Sol 1802 position about 10 meters (33 feet) away. For scale, the distance between the parallel wheel tracks is about one meter (40 inches). Where the receding tracks bend to the left, a circular pattern resulted from Spirit turning in place at a soil target informally named 'Stapledon' after William Olaf Stapledon, a British philosopher and science-fiction author who lived from 1886 to 1950. Scientists on the rover team suspected that the soil in that area might have a high concentration of silica, resembling a high-silica soil patch discovered east of Home Plate in 2007. Bright material visible in the track furthest to the right was examined with Spirit's alpha partical X-ray spectrometer and found, indeed, to be rich in silica. The team laid plans to drive Spirit from this Sol 1802 location back up

  15. Industrial applications of sol-gel technology

    International Nuclear Information System (INIS)

    Tuloch, S.M.; Tulloch, G.E.

    1995-01-01

    The purpose of this paper has been to provide a broad, rather than comprehensive view. We have presented a range of applications and only a selection of involved companies and researchers and have relied to a large extent on published information. Nevertheless, we are sure that our view of the importance of Sol-gel technology as an emerging technology, with enormous impact across a wide range of manufacturing, is demonstrated. Applications which are either in production or have been foreshadowed include four broad categories: coatings, fibres, powders and monoliths

  16. Plasmonic enhancement in upconversion emission of La2O3:Er3+/Yb3+ phosphor via introducing silver metal nanoparticles

    Science.gov (United States)

    Tiwari, S. P.; Kumar, K.; Rai, V. K.

    2015-11-01

    In the present work, authors have synthesized silver (Ag) nanoparticle (NP) embedded La2O3:Er3+/Yb3+ powder phosphor. The synthesis method has resulted in silver oxide-lanthanum oxide composite material. Through subsequent heat treatment of sample in pellet form, the silver metal nanoparticles were formed. The presence of plasmonic Ag NPs in the matrix is confirmed by various techniques. Large enhancement in downconversion as well as upconversion emission intensity of Er3+ ions at various concentrations of Ag NPs is obtained. Large enhancement in the upconversion emission intensity is correlated to the reduction in decay time of 4S3/2 level in the presence of Ag NPs, and possible reasons for intensity enhancement are discussed. The application of phosphor in fingermark detection is demonstrated.

  17. Montecarlo calculation of the isomeric cross sections ratio for the reaction 237Np(n,2n)236Np

    International Nuclear Information System (INIS)

    Cleri, F.

    1988-01-01

    A Montecarlo calculation of the isomeric cross section ratio for the (n,2n) reaction on 237 Np has been carried out based on the Hauser-Feshbach formulation. A standard energy-dependent optical model potential was used, with zero deformation parameters and no spin-orbit coupling. Investigation was made about the role of the energy cut-off value, of the higher multipole (E2) transition, of the gamma-ray versus second neutron emission, of the value of the spin cutt-off parameter. The results give the correct qualitative energy dependence of the branching ratio, with the assumption that the 1 - level is the ground state. The spin cut-off value obtained indicates a less pronounced deviation of the nuclear moment of inertia from the rigid-body value, with respect to older evaluations for high-mass nuclei. (author)

  18. The (n,p) reaction as a probe of nuclear structure

    International Nuclear Information System (INIS)

    Jackson, K.P.; Celler, A.

    1988-08-01

    An account is given of some results of studies of the (n,p) reaction on nuclear targets at TRIUMF. The (n,p) reaction, inducing spin flip transitions in isospin space, appears to exhibit a unique sensitivity to certain aspects of nuclear structure. The TRIUMF facility is the first to exploit the (n,p) reaction as a detailed probe of nuclear structure at energies above 65 MeV. In the (n,p) reaction Fermi transitions are absent, but there is a dramatic impact on Gamow-Teller and other collective transactions. Some nuclear transition matrix elements can be estimated on the basis of (n,p) measurements. Experiments have been carried out at TRIUMF on Li 6 , Fe 5 4, and Zr 9 0 targets. The calibration of the (n,p) reaction as a probe of the Gamow-Teller strength B + GT has been achieved for three targets. (L.L.) (45 refs., 10 figs.)

  19. Aging and soil organic matter content affect the fate of silver nanoparticles in soil

    International Nuclear Information System (INIS)

    Coutris, Claire; Joner, Erik Jautris; Oughton, Deborah Helen

    2012-01-01

    Sewage sludge application on soils represents an important potential source of silver nanoparticles (Ag NPs) to terrestrial ecosystems, and it is thus important to understand the fate of Ag NPs once in contact with soil components. Our aim was to compare the behavior of three different forms of silver, namely silver nitrate, citrate stabilized Ag NPs (5 nm) and uncoated Ag NPs (19 nm), in two soils with contrasting organic matter content, and to follow changes in binding strength over time. Soil samples were spiked with silver and left to age for 2 h, 2 days, 5 weeks or 10 weeks before they were submitted to sequential extraction. The ionic silver solution and the two Ag NP types were radiolabeled so that silver could be quantified by gamma spectrometry by measuring the 110m Ag tracer in the different sequential extraction fractions. Different patterns of partitioning of silver were observed for the three forms of silver. All types of silver were more mobile in the mineral soil than in the soil rich in organic matter, although the fractionation patterns were very different for the three silver forms in both cases. Over 20% of citrate stabilized Ag NPs was extractible with water in both soils the first two days after spiking (compared to 1–3% for AgNO 3 and uncoated Ag NPs), but the fraction decreased to trace levels thereafter. Regarding the 19 nm uncoated Ag NPs, 80% was not extractible at all, but contrary to AgNO 3 and citrate stabilized Ag NPs, the bioaccessible fraction increased over time, and by day 70 was between 8 and 9 times greater than that seen in the other two treatments. This new and unexpected finding demonstrates that some Ag NPs can act as a continuous source of bioaccessible Ag, while AgNO 3 is rapidly immobilized in soil. - Highlights: ► We compared the behavior of AgNO 3 and two types of Ag NPs in soil over time. ► AgNO 3 is rapidly immobilized in soil. ► Larger Ag NPs can act as a continuous source of bioaccessible Ag, which calls for

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

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

  1. ΔNp63 mediates cellular survival and metastasis in canine osteosarcoma.

    Science.gov (United States)

    Cam, Maren; Gardner, Heather L; Roberts, Ryan D; Fenger, Joelle M; Guttridge, Denis C; London, Cheryl A; Cam, Hakan

    2016-07-26

    p63 is a structural homolog within the 53 family encoding two isoforms, ΔNp63 and TAp63. The oncogenic activity of ΔNp63 has been demonstrated in multiple cancers, however the underlying mechanisms that contribute to tumorigenesis are poorly characterized. Osteosarcoma (OSA) is the most common primary bone tumor in dogs, exhibiting clinical behavior and molecular biology essentially identical to its human counterpart. The purpose of this study was to evaluate the potential contribution of ΔNp63 to the biology of canine OSA. As demonstrated by qRT-PCR, nearly all canine OSA cell lines and tissues overexpressed ΔNp63 relative to normal control osteoblasts. Inhibition of ΔNp63 by RNAi selectively induced apoptosis in the OSA cell lines overexpressing ΔNp63. Knockdown of ΔNp63 upregulated expression of the proapoptotic Bcl-2 family members Puma and Noxa independent of p53. However the effects of ΔNp63 required transactivating isoforms of p73, suggesting that ΔNp63 promotes survival in OSA by repressing p73-dependent apoptosis. In addition, ΔNp63 modulated angiogenesis and invasion through its effects on VEGF-A and IL-8 expression, and STAT3 phosphorylation. Lastly, the capacity of canine OSA cell lines to form pulmonary metastasis was directly related to expression levels of ΔNp63 in a murine model of metastatic OSA. Together, these data demonstrate that ΔNp63 inhibits apoptosis and promotes metastasis, supporting continued evaluation of this oncogene as a therapeutic target in both human and canine OSA.

  2. Discovery of the silver isotopes

    International Nuclear Information System (INIS)

    Schuh, A.; Fritsch, A.; Ginepro, J.Q.; Heim, M.; Shore, A.; Thoennessen, M.

    2010-01-01

    Thirty-eight silver isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  3. Low-silver radiographic detectors

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  4. Laser Processed Silver Nanowire Network Transparent Electrodes for Novel Electronic Devices

    Science.gov (United States)

    Spechler, Joshua Allen

    Silver nanowire network transparent conducting layers are poised to make headway into a space previously dominated by transparent conducting oxides due to the promise of a flexible, scaleable, lab-atmosphere processable alternative. However, there are many challenges standing in the way between research scale use and consumer technology scale adaptation of this technology. In this thesis we will explore many, and overcome a few of these challenges. We will address the poor conductivity at the narrow nanowire-nanowire junction points in the network by developing a laser based process to weld nanowires together on a microscopic scale. We address the need for a comparative metric for transparent conductors in general, by taking a device level rather than a component level view of these layers. We also address the mechanical, physical, and thermal limitations to the silver nanowire networks by making composites from materials including a colorless polyimide and titania sol-gel. Additionally, we verify our findings by integrating these processes into devices. Studying a hybrid organic/inorganic heterojunction photovoltaic device we show the benefits of a laser processed electrode. Green phosphorescent organic light emitting diodes fabricated on a solution phase processed silver nanowire based electrode show favorable device metrics compared to a conductive oxide electrode based control. The work in this thesis is intended to push the adoption of silver nanowire networks to further allow new device architectures, and thereby new device applications.

  5. Influence of silver doping on surface defect characteristics of TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, S. K., E-mail: surya@pu.ac.in [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India); Rani, Mamta [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India); Department of Physics, DAV University Jalandhar, - 144 001, Punjab (India)

    2015-08-28

    In the present work, we proposed a novel silver doped TiO{sub 2} polyethylene conjugated films to improve the performance of DSSCs. Oxides nanoparticles dispersed in a semiconducting polymer form the active layer of a solar cell. Localized surface plasmon resonance effects associated with spatially dispersed silver (Ag) nanoparticles can be exploited to enhance the light-harvesting efficiency, the photocurrent density and the overall light-to electrical-energy-conversion efficiency of high-area DSSCs based TiO{sub 2} photoanodes. Silver doped titanium dioxide (TiO{sub 2}:Ag) is prepared by sol-gel technique and deposited on fluorine doped indium oxide (FTO) coated glass substrates by using doctor blade technique at 550°C from aqueous solutions of titanium butoxide and silver nitrate precursors. The effect of Ag doping on electrical properties of films is studied. The Ag-TiO{sub 2} films are about 548 times more photosensitive as compare to the pure TiO{sub 2} sample. The presence of metallic Ag nanoparticles and oxygen vacancy on the surface of TiO{sub 2} nanoparticles promotes the separation of photogenerated electron-hole pairs and thus enhances the photosensitivity. Photoconduction mechanism of all prepared samples is investigated by performing transient photoconductivity measurements on TiO{sub 2} and Ag-TiO{sub 2} films keeping intensity of light constant.

  6. Study of optical and physicochemical properties of colloidal silver nanoparticles as an efficient substrate for SERS

    International Nuclear Information System (INIS)

    Cyrankiewicz, M; Kruszewski, S

    2011-01-01

    The unique optical and physicochemical properties of the noble metal colloidal nanoparticles enable their use in a wide range of applications, especially as a substrate in SERS and MEF study. The aim of this work is to characterize the conditions for the enhancement of Raman scattering by molecules adsorbed on silver surface. Silver sol is prepared by slightly modified Lee-Meisel's method and rhodamine 6G is used as a probe adsorbate. Pure colloidal silver suspension containing isolated nanoparticles exhibits relatively poor SERS efficiency. The extremely large electromagnetic field is induced in the junctions between two or more metallic nanocrystalites so some degree of their aggregation is necessary. The influence of potassium chloride and nitric acid as the aggregating agents is investigated here. The experiments show that both of them can promote the controlled aggregation process but chloride anions, unlike nitrate, much more effectively affect both electromagnetic and chemical mechanisms contributing to SERS. Due to the co-adsorption with rhodamine 6G they allow the dye molecules to directly interact with metallic surface. Moreover, the results clearly indicate that chloride in the presence of silver particles can induce the dimerization of the dye molecules.

  7. ΔNp73 enhances promoter activity of TGF-β induced genes.

    Directory of Open Access Journals (Sweden)

    Maarten Niemantsverdriet

    Full Text Available The p53 homolog p73 is frequently overexpressed in cancers. Especially the transactivation domain truncated isoform ΔNp73 has oncogenic properties and its upregulation is associated with poor patient survival. It has been shown that ΔNp73 has an inhibitory effect on the transactivation capacity of p53 and other p73 isoforms. Here, we confirm this finding but surprisingly find that ΔNp73 may also stimulate the expression of TGF-β signaling targets. Promoter-reporter analysis indicated that the presence of Smad Binding Elements (SBE in the promoter is sufficient for stimulation of gene expression by ΔNp73. TGF-β signaling was less efficient in ΔNp73 downregulated cells, whereas tetracycline induced ΔNp73 increased expression of endogenous TGF-β regulated genes PAI-1 and Col1a1. Pull-down assays with SBE DNA suggest that ΔNp73 enhances smad3/4 binding to SBEs, thereby stimulating TGF-β signaling. Chromatin immunoprecipitation assays confirmed a direct interaction between ΔNp73 and SBE. Given the role of TGF-β signaling in carcinogenesis, tumor invasion and metastasis via targets like PAI-1 and Col1a1, our data suggest a model on how this effect of ΔNp73 could be a contributing factor in cancer progression.

  8. Perspectives for photonuclear research at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility

    Energy Technology Data Exchange (ETDEWEB)

    Filipescu, D.; Balabanski, D.L.; Constantin, P.; Gales, S.; Tesileanu, O.; Ur, C.A.; Ursu, I.; Zamfir, N.V. [Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering (IFIN-HH), Extreme Light Infrastructure - Nuclear Physics (ELI-NP), Bucharest-Magurele (Romania); Anzalone, A.; La Cognata, M.; Spitaleri, C. [INFN-LNS, Catania (Italy); Belyshev, S.S. [Lomonosov Moscow State University, Physics Faculty, Moscow (Russian Federation); Camera, F. [Departement of Physics, University of Milano, Milano (Italy); INFN section of Milano, Milano (Italy); Csige, L.; Krasznahorkay, A. [Hungarian Academy of Sciences (MTA Atomki), Institute of Nuclear Research, Post Office Box 51, Debrecen (Hungary); Cuong, P.V. [Vietnam Academy of Science and Technology, Centre of Nuclear Physics, Institute of Physics, Hanoi (Viet Nam); Cwiok, M.; Dominik, W.; Mazzocchi, C. [University of Warsaw, Warszawa (Poland); Derya, V.; Zilges, A. [University of Cologne, Institute for Nuclear Physics, Cologne (Germany); Gai, M. [University of Connecticut, LNS at Avery Point, Connecticut, Groton (United States); Gheorghe, I. [Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering (IFIN-HH), Extreme Light Infrastructure - Nuclear Physics (ELI-NP), Bucharest-Magurele (Romania); University of Bucharest, Nuclear Physics Department, Post Office Box MG-11, Bucharest-Magurele (Romania); Ishkhanov, B.S. [Lomonosov Moscow State University, Physics Faculty, Moscow (Russian Federation); Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Kuznetsov, A.A.; Orlin, V.N.; Stopani, K.A.; Varlamov, V.V. [Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Pietralla, N. [Technische Universitat Darmstadt, Institut fur Kernphysik, Darmstadt (Germany); Sin, M. [University of Bucharest, Nuclear Physics Department, Post Office Box MG-11, Bucharest-Magurele (Romania); Utsunomiya, H. [Konan University, Department of Physics, Kobe (Japan); University of Tokyo, Center for Nuclear Study, Saitama (Japan); Weller, H.R. [Triangle Universities Nuclear Laboratory, North Carolina, Durham (United States); Duke University, Department of Physics, North Carolina, Durham (United States)

    2015-12-15

    The perspectives for photonuclear experiments at the new Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility are discussed in view of the need to accumulate novel and more precise nuclear data. The parameters of the ELI-NP gamma beam system are presented. The emerging experimental program, which will be realized at ELI-NP, is presented. Examples of day-one experiments with the nuclear resonance fluorescence technique, photonuclear reaction measurements, photofission experiments and studies of nuclear collective excitation modes and competition between various decay channels are discussed. The advantages which ELI-NP provides for all these experiments compared to the existing facilities are discussed. (orig.)

  9. Effect of silver nanoparticles on Mediterranean sea urchin embryonal development is species specific and depends on moment of first exposure.

    Science.gov (United States)

    Burić, Petra; Jakšić, Željko; Štajner, Lara; Dutour Sikirić, Maja; Jurašin, Darija; Cascio, Claudia; Calzolai, Luigi; Lyons, Daniel Mark

    2015-10-01

    With the ever growing use of nanoparticles in a broad range of industrial and consumer applications there is increasing likelihood that such nanoparticles will enter the aquatic environment and be transported through freshwater systems, eventually reaching estuarine or marine waters. Due to silver's known antimicrobial properties and widespread use of silver nanoparticles (AgNP), their environmental fate and impact is therefore of particular concern. In this context we have investigated the species-specific effects of low concentrations of 60 nm AgNP on embryonal development in Mediterranean sea urchins Arbacia lixula, Paracentrotus lividus and Sphaerechinus granularis. The sensitivity of urchin embryos was tested by exposing embryos to nanoparticle concentrations in the 1-100 μg L(-1) range, with times of exposure varying from 30 min to 24 h (1 h-48 h for S. granularis) post-fertilisation which corresponded with fertilized egg, 4 cell, blastula and gastrula development phases. The most sensitive species to AgNP was A. lixula with significant modulation of embryonal development at the lowest AgNP concentrations of 1-10 μg L(-1) with high numbers of malformed embryos or arrested development. The greatest impact on development was noted for those embryos first exposed to nanoparticles at 6 and 24 h post fertilisation. For P. lividus, similar effects were noted at higher concentrations of 50 μg L(-1) and 100 μg L(-1) for all times of first exposure. The S. granularis embryos indicated a moderate AgNP impact, and significant developmental abnormalities were recorded in the concentration range of 10-50 μg L(-1). As later post-fertilisation exposure times to AgNP caused greater developmental changes in spite of a shorter total exposure time led us to postulate on additional mechanisms of AgNP toxicity. The results herein indicate that toxic effects of AgNP are species-specific. The moment at which embryos first encounter AgNP is also shown to be

  10. Opportunity's Surroundings on Sol 1798 (Stereo)

    Science.gov (United States)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11850 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11850 NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this stereo 180-degree view of the rover's surroundings during the 1,798th Martian day, or sol, of Opportunity's surface mission (Feb. 13, 2009). North is on top. This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left. The rover had driven 111 meters (364 feet) southward on the preceding sol. Tracks from that drive recede northward in this view. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock. This view is presented as a cylindrical-perspective projection with geometric seam correction.

  11. Opportunity's Surroundings on Sol 1818 (Stereo)

    Science.gov (United States)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11846 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11846 NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,818th Martian day, or sol, of Opportunity's surface mission (March 5, 2009). South is at the center; north at both ends. This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left. The rover had driven 80.3 meters (263 feet) southward earlier on that sol. Tracks from the drive recede northward in this view. The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and lighter-toned bedrock. This view is presented as a cylindrical-perspective projection with geometric seam correction.

  12. Spirit Beside 'Home Plate,' Sol 1809 (Stereo)

    Science.gov (United States)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11803 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11803 NASA Mars Exploration Rover Spirit used its navigation camera to take the images assembled into this stereo, 120-degree view southward after a short drive during the 1,809th Martian day, or sol, of Spirit's mission on the surface of Mars (February 3, 2009). By combining images from the left-eye and right-eye sides of the navigation camera, the view appears three-dimensional when viewed through red-blue glasses with the red lens on the left. Spirit had driven about 2.6 meters (8.5 feet) that sol, continuing a clockwise route around a low plateau called 'Home Plate.' In this image, the rocks visible above the rovers' solar panels are on the slope at the northern edge of Home Plate. This view is presented as a cylindrical-perspective projection with geometric seam correction.

  13. Sol-gel precursors and products thereof

    Science.gov (United States)

    Warren, Scott C.; DiSalvo, Jr., Francis J.; Weisner, Ulrich B.

    2017-02-14

    The present invention provides a generalizable single-source sol-gel precursor capable of introducing a wide range of functionalities to metal oxides such as silica. The sol-gel precursor facilitates a one-molecule, one-step approach to the synthesis of metal-silica hybrids with combinations of biological, catalytic, magnetic, and optical functionalities. The single-source precursor also provides a flexible route for simultaneously incorporating functional species of many different types. The ligands employed for functionalizing the metal oxides are derived from a library of amino acids, hydroxy acids, or peptides and a silicon alkoxide, allowing many biological functionalities to be built into silica hybrids. The ligands can coordinate with a wide range of metals via a carboxylic acid, thereby allowing direct incorporation of inorganic functionalities from across the periodic table. Using the single-source precursor a wide range of functionalized nanostructures such as monolith structures, mesostructures, multiple metal gradient mesostructures and Stober-type nanoparticles can be synthesized. ##STR00001##

  14. Opportunity's Surroundings After Sol 1820 Drive (Stereo)

    Science.gov (United States)

    2009-01-01

    [figure removed for brevity, see original site] Left-eye view of a color stereo pair for PIA11841 [figure removed for brevity, see original site] Right-eye view of a color stereo pair for PIA11841 NASA's Mars Exploration Rover Opportunity used its navigation camera to take the images combined into this full-circle view of the rover's surroundings during the 1,820th to 1,822nd Martian days, or sols, of Opportunity's surface mission (March 7 to 9, 2009). This view combines images from the left-eye and right-eye sides of the navigation camera. It appears three-dimensional when viewed through red-blue glasses with the red lens on the left. The rover had driven 20.6 meters toward the northwest on Sol 1820 before beginning to take the frames in this view. Tracks from that drive recede southwestward. For scale, the distance between the parallel wheel tracks is about 1 meter (about 40 inches). The terrain in this portion of Mars' Meridiani Planum region includes dark-toned sand ripples and small exposures of lighter-toned bedrock. This view is presented as a cylindrical-perspective projection with geometric seam correction.

  15. Dip coating of sol-gels

    Science.gov (United States)

    Schunk, P. R.; Hurd, A. J.; Brinker, C. J.

    Dip coating is the primary means of depositing sol-gel films for precision optical coatings. Sols are typically multicomponent systems consisting of an inorganic phase dispersed in a solvent mixture, with each component differing in volatility and surface tension. This, together with slow coating speeds (less than 1cm/s), makes analysis of the coating process complicated; unlike most high-speed coating methods, solvent evaporation, evolving rheology, and surface tension gradients alter significantly the fluid mechanics of the deposition stage. These phenomena were studied with computer-aided predictions of the flow and species transport fields. The underlying theory involves mass, momentum, and species transport on a domain of unknown shape, with models and constitutive equations for vapor-liquid equilibria and surface tension. Due accounting is made for the unknown position of the free surface, which locates according to the capillary hydrodynamic forces and solvent loss by evaporation. Predictions of the effects of mass transfer, hydrodynamics, and surface tension gradients on final film thickness are compared with ellipsometry measurements of film thickness on a laboratory pilot coater. Although quantitative agreement is still lacking, both experiment and theory reveal that the film profile near the drying line takes on a parabolic shape.

  16. Opportunity's Sol 446 Position, with Relative Heights

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Figure 1: Coding for Information About Relative Elevations This mosaic of navigation-camera frames from NASA's Mars Exploration Rover Opportunity, presented in a vertical projection, shows the rover's position after it dug itself to wheel-hub depth in a small dune during its 446th martian day, or sol (April 26, 2005). In figure 1, the colors are coding for information about relative elevations in the surrounding area. Red areas are the highest in the image, green areas the lowest. The difference between red and green is about 70 centimeters (28 inches). The elongated dune, or ripple, is about one-third of a meter (one foot) tall and 2.5 meters (8 feet) wide. Opportunity had completed nearly 40 meters (131 feet) of a planned 90-meter (295-foot) drive that sol when its wheels began slipping. The rover was driving backwards at the time. The rover team frequently alternates between backwards and forwards driving to keep wheel lubrication well distributed. The wheels kept rotating enough times to have covered the rest of the distance if they hadn't been slipping, but the rover eventually barely inched forward. After a turn at the end of the planned drive, Opportunity sensed that it had not turned properly and stopped moving. The rover team spent more than a week designing and conducting tests under simulated Mars conditions on Earth before choosing the best way for Opportunity to drive out of the dune.

  17. Sol-gel coatings on carbon/carbon composites

    International Nuclear Information System (INIS)

    Sim, S.M.; Krabill, R.M.; Dalzell, W.J. Jr.; Chu, P.Y.; Clark, D.E.

    1986-01-01

    The need for structural materials that can withstand severe environments up to 4000 0 F has promulgated the investigation of sol-gel derived ceramic and composite coatings on carbon/carbon composite materials. Alumina and zirconia sols have been deposited via thermophoresis on carbon/carbon substrates

  18. Structural evolution of silica sols modified with formamide

    Directory of Open Access Journals (Sweden)

    Lenza R.F.S.

    2001-01-01

    Full Text Available In this work we investigated the influence of formamide on the acid-catalyzed sol-gel process by Fourier transform infrared spectroscopy (FTIR. Three silica sols were studied: Sol catalyzed with nitric acid without formamide, sol catalyzed with nitric acid containing formamide and sol catalyzed with a mixture of nitric acid and hydrofluoric acid and modified with formamide. Following the time evolution of both the Si-(OH stretching vibration at around 950 cm-1 and the Si-O-(Si vibration between 1040 cm-1 and 1200 cm-1 we were able to describe the structural evolution of each sol. The curve of evolution of Si-(OH stretching vibration corresponding to sol A has a simple asymptotic evolution. In the case of formamide containing sol, we observed a two-step structural evolution indicating that for the system containing formamide the polymerization goes through a temporary stabilization of oligomers, which can explain the non-variation of the Si-O(H bond wavenumber for a certain time. Gelation times were of several days for gels without formamide and few hours for gels containing additive. The presence of additive resulted in a highly interconnected gel.

  19. Biocatalysis with Sol-Gel Encapsulated Acid Phosphatase

    Science.gov (United States)

    Kulkarni, Suhasini; Tran, Vu; Ho, Maggie K.-M.; Phan, Chieu; Chin, Elizabeth; Wemmer, Zeke; Sommerhalter, Monika

    2010-01-01

    This experiment was performed in an upper-level undergraduate biochemistry laboratory course. Students learned how to immobilize an enzyme in a sol-gel matrix and how to perform and evaluate enzyme-activity measurements. The enzyme acid phosphatase (APase) from wheat germ was encapsulated in sol-gel beads that were prepared from the precursor…

  20. Application of the docking program SOL for CSAR benchmark.

    Science.gov (United States)

    Sulimov, Alexey V; Kutov, Danil C; Oferkin, Igor V; Katkova, Ekaterina V; Sulimov, Vladimir B

    2013-08-26

    This paper is devoted to results obtained by the docking program SOL and the post-processing program DISCORE at the CSAR benchmark. SOL and DISCORE programs are described. SOL is the original docking program developed on the basis of the genetic algorithm, MMFF94 force field, rigid protein, precalculated energy grid including desolvation in the frame of simplified GB model, vdW, and electrostatic interactions and taking into account the ligand internal strain energy. An important SOL feature is the single- or multi-processor performance for up to hundreds of CPUs. DISCORE improves the binding energy scoring by the local energy optimization of the ligand docked pose and a simple linear regression on the base of available experimental data. The docking program SOL has demonstrated a good ability for correct ligand positioning in the active sites of the tested proteins in most cases of CSAR exercises. SOL and DISCORE have not demonstrated very exciting results on the protein-ligand binding free energy estimation. Nevertheless, for some target proteins, SOL and DISCORE were among the first in prediction of inhibition activity. Ways to improve SOL and DISCORE are discussed.

  1. Self-Healing Corrosion Protective Sol-Gel Coatings

    NARCIS (Netherlands)

    Abdolah Zadeh, M.

    2016-01-01

    Inspired by the state of the art and the recent advances in the field of self-healing corrosion protective coatings, the thesis entitled “Self-healing corrosion protective sol-gel coatings” addresses novel routes to self-healing corrosion protective sol-gel coatings via extrinsic and intrinsic

  2. Analyses of laser and furnace treated sol-gel coatings

    NARCIS (Netherlands)

    De Hosson, JT; De Haas, M; Sudarshan, TS; Jeandin, M; Khor, KA

    1998-01-01

    Here we explore a new method that allows thin films to be made with almost any composition and degree of porosity by means of a combination of sol-gel and laser technology. Results are presented for furnace and laser treated TEOTI-(tetraethylorthotitanate as sol precursor) coated silicon samples.

  3. Tryptophan-Assisted Synthesis Reduces Bimetallic Gold/Silver Nanoparticle Cytotoxicity and Improves Biological Activity

    Directory of Open Access Journals (Sweden)

    Igor O. Shmarakov

    2014-10-01

    Full Text Available Aiming to reduce the potential in vivo hepato-and nephrotoxicity of Ag/Au bimetallic nanoparticles (NPs stabilized by sodium dodecyl sulphate (SDS, an approach involving a simultaneous reduction of silver nitrate and tetrachlorauratic acid using tryptophan (Trp as a reducing/stabilizing agent was applied during NP synthesis. The obtained Ag/Au/Trp NPs (5–15 nm sized were able to form stable aggregates with an average size of 370–450 nm and were potentially less toxic than Ag/Au/SDS in relation to a mouse model system based on clinical biochemical parameters and oxidative damage product estimation. Ag/Au/Trp NPs were shown to exhibit anticancer activity in relation to a Lewis lung carcinoma model. The data generated from the present study support the fact that the use of tryptophan in NP synthesis is effective in attenuating the potential hepatotoxicity and nephrotoxicity of NPs during their in vivo application.

  4. Rapid biosynthesis and characterization of silver nanoparticles: an assessment of antibacterial and antimycotic activity

    Science.gov (United States)

    Kanawaria, Sajjan Kumar; Sankhla, Aryan; Jatav, Pradeep Kumar; Yadav, Raghvendra Singh; Verma, Kumar Sambhav; Velraj, Parthiban; Kachhwaha, Sumita; Kothari, Shanker Lal

    2018-04-01

    Bioassisted synthesis provides a facile, convenient, and promising approach to produce many inorganic nanostructures. Herein, we report a rapid biosynthesis of silver nanoparticles (AgNPs) using Thuja occidentalis (L.) leaf extract with an emphasis on their antibacterial and antimycotic activity. Interestingly, the synthesis of AgNPs was completed in a short duration of 35-40 min. The electron micrographs showed AgNPs with particles Bacillus subtilis. An AgNP solution with 30 µg/ml concentration arrested the growth of bacterial strains making a zone of inhibition > 15 mm. The antimycotic activity against Aspergillus niger, Fusarium spp., and Alternaria alternata species increased monotonically with nanoparticle concentration in the growth media. A 10 ppm solution of AgNP was detrimental to fungal growth. Thus, the technique provides an avenue to synthesize antibiotic AgNPs without use of other external agents.

  5. Silver, gold and the corresponding core shell nanoparticles: synthesis and characterization

    International Nuclear Information System (INIS)

    Douglas, Fraser; Yanez, Ramon; Ros, Josep; Marin, Sergio; Escosura-Muniz, Alfredo de la; Alegret, Salvador; Merkoci, Arben

    2008-01-01

    Simple strategies for producing silver and gold nanoparticles (AgNP and AuNP) along with the corresponding core shell nanoparticles (Au-Ag and Ag-Au) by reduction of the metal salts AgBF 4 and HAuCl 4 by NaBH 4 in water will be presented. The morphologies of the obtained nanoparticles are determined by the order of addition of reactants. The obtained NPs, with sizes in the range 3-40 nm, are characterized by transmission electronic microscopy (TEM) and UV-Vis absorption spectroscopy, so as to evaluate their qualities. Moreover, a direct electrochemical detection protocol based on a cyclic voltammetry in water solution that involves the use of glassy carbon electrode is also applied to characterize the prepared NPs. The developed NPs and the related electroanalytical method seem to be with interest for future sensing and biosensing applications including DNA sensors and immunosensors.

  6. Effect of natural phosphate to remove silver interference in the detection of mercury(II) in aquatic algae and seawater samples

    OpenAIRE

    S. Lahrich; H. Hammani; W. Boumya; A. Loudiki; El Bouabi; R. Elmoubarki; A. Farahi; M. Achak; M. Bakasse; M.A. El Mhammedi

    2016-01-01

    A silver particles impregnated onto natural phosphate (Ag/NP) was synthesized using reaction in solid state. The obtained powder was characterized by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The (Ag/NP) was used as modifier of carbon paste electrode (CPE) to determine mercury by square wave voltammetry. The calibration graph obtained is linear from 1.0 × 10−8 mol·L−1 to 1.0 × 10−5 mol·L−1 at preconcentration time of 5 min, percentage loading of 7%, with correla...

  7. Silver nanoparticles cause complications in pregnant mice

    Directory of Open Access Journals (Sweden)

    Zhang XF

    2015-11-01

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

  8. The release of silver nanoparticles from commercial toothbrushes

    International Nuclear Information System (INIS)

    Mackevica, Aiga; Olsson, Mikael Emil; Hansen, Steffen Foss

    2017-01-01

    Highlights: • Ag and Ag nanoparticle release was measured from two types of toothbrushes. • Maximum release for entire intended product use period was 10 ng Ag per toothbrush. • Released Ag nanoparticles had median sizes from 42 to 47 nm. • Up to 2.8% of total Ag released was detected in nanoparticulate form. - Abstract: The use of silver nanoparticles (NPs) in commercial products has become increasingly common in the past decade, mostly due to their antimicrobial properties. Using Ag NP-containing articles may lead to particle release, which raises concern of human and environmental safety. The published literature addressing particle release is scarce, especially when it comes to quantifying exposure to NPs specifically. In this study, we have experimentally investigated the release of total Ag and Ag NP from commercially available toothbrushes i.e. biodegradable toothbrushes for adults and toothbrushes for children. Toothbrushes were immersed and abraded in tap water for 24 h corresponding to more than the whole intended usage time of a toothbrush. The total amount of released Ag was quantified by inductively coupled plasma—mass spectrometry (ICP-MS) analysis, and the Ag NPs were characterized by single particle ICP-MS and transmission electron microscopy (TEM). The median size of the released Ag NPs ranged from 42 to 47 nm, and the maximum total Ag release was 10.2 ng per toothbrush. The adult toothbrushes were generally releasing more total Ag and NPs than children toothbrushes. In conclusion, our results indicate that the use of Ag NP-impregnated toothbrushes can cause consumer as well as environmental exposure to Ag NPs.

  9. The release of silver nanoparticles from commercial toothbrushes

    Energy Technology Data Exchange (ETDEWEB)

    Mackevica, Aiga, E-mail: aima@env.dtu.dk; Olsson, Mikael Emil; Hansen, Steffen Foss

    2017-01-15

    Highlights: • Ag and Ag nanoparticle release was measured from two types of toothbrushes. • Maximum release for entire intended product use period was 10 ng Ag per toothbrush. • Released Ag nanoparticles had median sizes from 42 to 47 nm. • Up to 2.8% of total Ag released was detected in nanoparticulate form. - Abstract: The use of silver nanoparticles (NPs) in commercial products has become increasingly common in the past decade, mostly due to their antimicrobial properties. Using Ag NP-containing articles may lead to particle release, which raises concern of human and environmental safety. The published literature addressing particle release is scarce, especially when it comes to quantifying exposure to NPs specifically. In this study, we have experimentally investigated the release of total Ag and Ag NP from commercially available toothbrushes i.e. biodegradable toothbrushes for adults and toothbrushes for children. Toothbrushes were immersed and abraded in tap water for 24 h corresponding to more than the whole intended usage time of a toothbrush. The total amount of released Ag was quantified by inductively coupled plasma—mass spectrometry (ICP-MS) analysis, and the Ag NPs were characterized by single particle ICP-MS and transmission electron microscopy (TEM). The median size of the released Ag NPs ranged from 42 to 47 nm, and the maximum total Ag release was 10.2 ng per toothbrush. The adult toothbrushes were generally releasing more total Ag and NPs than children toothbrushes. In conclusion, our results indicate that the use of Ag NP-impregnated toothbrushes can cause consumer as well as environmental exposure to Ag NPs.

  10. Time for a Change; Spirit's View on Sol 1843

    Science.gov (United States)

    2009-01-01

    NASA's Mars Exploration Rover Spirit used its navigation camera to take the images that have been combined into this full-circle view of the rover's surroundings during the 1,843rd Martian day, or sol, of Spirit's surface mission (March 10, 2009). South is in the middle. North is at both ends. The rover had driven 36 centimeters downhill earlier on Sol 1854, but had not been able to get free of ruts in soft material that had become an obstacle to getting around the northeastern corner of the low plateau called 'Home Plate.' The Sol 1854 drive, following two others in the preceding four sols that also achieved little progress in the soft ground, prompted the rover team to switch to a plan of getting around Home Plate counterclockwise, instead of clockwise. The drive direction in subsequent sols was westward past the northern edge of Home Plate. This view is presented as a cylindrical projection with geometric seam correction.

  11. Fast temperature fluctuation measurements in SOL of tokamak TCV

    DEFF Research Database (Denmark)

    Horacek, J.; Nielsen, Anders Henry; Pitts, R.A.

    to compare the statistical character of turbulence in the SOL particle flux on TCV with results from the 2D fluid electrostatic model ESEL [2][4]. Using results from the fast sweeping, similar comparisons can now be made with the fluctuating Te and will be described in this contribution. We also present...... basic statistics derived from the Te time series obtained at different radii in the SOL plasma and show, in particular, that the relationship between higher moments of the probability distribution function from both experimental and simulated Te’s may be well described by the Beta probability...... distribution function, introduced for SOL turbulence in [5]. The fast Te capability also allows the SOL response to Edge Localised Modes (ELMs) to be studied and new results will be presented for the far SOL Te response during Type III ELMs....

  12. Electrophoretic deposition of sol-gel-derived ceramic coatings

    International Nuclear Information System (INIS)

    Zhang, Y.; Crooks, R.M.

    1992-01-01

    In this paper the physical, optical, and chemical characteristics of electrophoretically and dip-coated sol-gel ceramic films are compared. The results indicate that electrophoresis may allow a higher level of control over the chemistry and structure of ceramic coatings than dip-coating techniques. For example, controlled-thickness sol-gel coatings can be prepared by adjusting the deposition time or voltage. Additionally, electrophoretic coatings can be prepared in a four-component alumino-borosilicate sol display interesting optical characteristics. For example, the ellipsometrically-measured refractive indices of electrophoretic coatings are higher than the refractive indices of dip-coated films cast from identical sols, and they are also higher than any of the individual sol components. This result suggests that there are physical and/or chemical differences between films prepared by dip-coating and electrophoresis

  13. Green synthesis and characterization of silver nanoparticles using Artemisia absinthium aqueous extract — A comprehensive study

    International Nuclear Information System (INIS)

    Ali, Mohammad; Kim, Bosung; Belfield, Kevin D.; Norman, David; Brennan, Mary; Ali, Gul Shad

    2016-01-01

    Unlike chemical synthesis, biological synthesis of nanoparticles is gaining tremendous interest, and plant extracts are preferred over other biological sources due to their ample availability and wide array of reducing metabolites. In this project, we investigated the reducing potential of aqueous extract of Artemisia absinthium L. for synthesizing silver nanoparticles (AgNPs). Optimal synthesis of AgNPs with desirable physical and biological properties was investigated using ultra violet–visible spectroscopy (UV–vis), dynamic light scattering (DLS), transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDX). To determine their appropriate concentrations for AgNP synthesis, two-fold dilutions of silver nitrate (20 to 0.62 mM) and aqueous plant extract (100 to 0.79 mg ml"−"1) were reacted. The results showed that silver nitrate (2 mM) and plant extract (10 mg ml"−"1) mixed in different ratios significantly affected size, stability and yield of AgNPs. Extract to AgNO_3 ratio of 6:4 v/v resulted in the highest conversion efficiency of AgNO_3 to AgNPs, with the particles in average size range of less than 100 nm. Furthermore, the direct imaging of synthesized AgNPs by TEM revealed polydispersed particles in the size range of 5 to 20 nm. Similarly, nanoparticles with the characteristic peak of silver were observed with EDX. This study presents a comprehensive investigation of the differential behavior of plant extract and AgNO_3 to synthesize biologically stable AgNPs. - Graphical abstract: Aqueous extract from Artemisia absinthium when used in appropriate ratio (shown in Eppendorf tubes and microtiter plate) is highly active in reducing elemental silver to colloidal silver nanoparticles in the 5–20 nm size range (shown in TEM image, bottom left panel; DLS histogram, upper left panel; EDX analysis, bottom right panel). - Highlights: • Artemisia absinthium extract provides excellent reducing potential for biosynthesis of silver

  14. Green synthesis and characterization of silver nanoparticles using Artemisia absinthium aqueous extract — A comprehensive study

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Mohammad [Mid-Florida Research and Education Center and Department of Plant Pathology, University of Florida/Institute of Food and Agricultural Sciences, 2725 Binion Rd., Apopka, FL 32703 (United States); Kim, Bosung [Department of Chemistry, University of Central Florida, Orlando, FL 32816 (United States); Belfield, Kevin D. [Department of Chemistry, University of Central Florida, Orlando, FL 32816 (United States); College of Science and Liberal Arts, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Norman, David; Brennan, Mary [Mid-Florida Research and Education Center and Department of Plant Pathology, University of Florida/Institute of Food and Agricultural Sciences, 2725 Binion Rd., Apopka, FL 32703 (United States); Ali, Gul Shad, E-mail: gsali@ufl.edu [Mid-Florida Research and Education Center and Department of Plant Pathology, University of Florida/Institute of Food and Agricultural Sciences, 2725 Binion Rd., Apopka, FL 32703 (United States)

    2016-01-01

    Unlike chemical synthesis, biological synthesis of nanoparticles is gaining tremendous interest, and plant extracts are preferred over other biological sources due to their ample availability and wide array of reducing metabolites. In this project, we investigated the reducing potential of aqueous extract of Artemisia absinthium L. for synthesizing silver nanoparticles (AgNPs). Optimal synthesis of AgNPs with desirable physical and biological properties was investigated using ultra violet–visible spectroscopy (UV–vis), dynamic light scattering (DLS), transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDX). To determine their appropriate concentrations for AgNP synthesis, two-fold dilutions of silver nitrate (20 to 0.62 mM) and aqueous plant extract (100 to 0.79 mg ml{sup −1}) were reacted. The results showed that silver nitrate (2 mM) and plant extract (10 mg ml{sup −1}) mixed in different ratios significantly affected size, stability and yield of AgNPs. Extract to AgNO{sub 3} ratio of 6:4 v/v resulted in the highest conversion efficiency of AgNO{sub 3} to AgNPs, with the particles in average size range of less than 100 nm. Furthermore, the direct imaging of synthesized AgNPs by TEM revealed polydispersed particles in the size range of 5 to 20 nm. Similarly, nanoparticles with the characteristic peak of silver were observed with EDX. This study presents a comprehensive investigation of the differential behavior of plant extract and AgNO{sub 3} to synthesize biologically stable AgNPs. - Graphical abstract: Aqueous extract from Artemisia absinthium when used in appropriate ratio (shown in Eppendorf tubes and microtiter plate) is highly active in reducing elemental silver to colloidal silver nanoparticles in the 5–20 nm size range (shown in TEM image, bottom left panel; DLS histogram, upper left panel; EDX analysis, bottom right panel). - Highlights: • Artemisia absinthium extract provides excellent reducing potential for

  15. Organic-Modified Silver Nanoparticles as Lubricant Additives.

    Science.gov (United States)

    Kumara, Chanaka; Luo, Huimin; Leonard, Donovan N; Meyer, Harry M; Qu, Jun

    2017-10-25

    Advanced lubrication is essential in human life for improving mobility, durability, and efficiency. Here we report the synthesis, characterization, and evaluation of two groups of oil-suspendable silver nanoparticles (NPs) as candidate lubricant additives. Two types of thiolated ligands, 4-(tert-butyl)benzylthiol (TBBT) and dodecanethiol (C12), were used to modify Ag NPs in two size ranges, 1-3 and 3-6 nm. The organic surface layer successfully suspended the Ag NPs in a poly-alpha-olefin (PAO) base oil with concentrations up to 0.19-0.50 wt %, depending on the particle type. Use of the Ag NPs in the base oil reduced friction by up to 35% and wear by up to 85% in boundary lubrication. The two TBBT-modified NPs produced a lower friction coefficient than the C12-modified one, while the two larger NPs (3-6 nm) had better wear protection than the smaller one (1-3 nm). Results suggested that the molecular structure of the organic ligand might have a dominant effect on the friction behavior, while the NP size could be more influential in the wear protection. No mini-ball-bearing or surface smoothening effects were observed in the Stribeck scans. Instead, the wear protection in boundary lubrication was attributed to the formation of a silver-rich 50-100 nm thick tribofilm on the worn surface, as revealed by morphology examination and composition analysis from both the top surface and cross section.

  16. Effect of different densities of silver nanoparticles on neuronal growth

    Energy Technology Data Exchange (ETDEWEB)

    Nissan, Ifat [Bar-Ilan University, Department of Chemistry (Israel); Schori, Hadas [Bar-Ilan University, Faculty of Engineering (Israel); Lipovsky, Anat [Bar-Ilan University, Department of Chemistry (Israel); Alon, Noa [Bar-Ilan University, Faculty of Engineering (Israel); Gedanken, Aharon, E-mail: gedanken@biu.ac.il [Bar-Ilan University, Department of Chemistry (Israel); Shefi, Orit, E-mail: orit.shefi@biu.ac.il [Bar-Ilan University, Faculty of Engineering (Israel)

    2016-08-15

    Nerve regeneration has become a subject of great interest, and much effort is devoted to the design and manufacturing of effective biomaterials. In this paper, we report the capability of surfaces coated with silver nanoparticles (AgNPs) to serve as platforms for nerve regeneration. We fabricated substrates coated with silver nanoparticles at different densities using sonochemistry, and grew neuroblastoma cells on the AgNPs. The effect of the different densities on the development of the neurites during the initiation and elongation growth phases was studied. We found that the AgNPs function as favorable anchoring sites for the neuroblastoma cells, significantly enhancing neurite outgrowth. One of the main goals of this study is to test whether the enhanced growth of the neurites is due to the mere presence of AgNPs or whether their topography also plays a vital role. We found that this phenomenon was repeated for all the tested densities, with a maximal effect for the substrates that are coated with 45 NPs/μm{sup 2}. We also studied the amount of reactive oxygen spices (ROS) in the presence of AgNPs as indicator of cell activation. Our results, combined with the well-known antibacterial effects of AgNPs, suggest that substrates coated with AgNP are attractive nanomaterials—with dual activity—for neuronal repair studies and therapeutics.Graphical Abstract.

  17. Purification and biochemical characterization of NpABCG5/NpPDR5, a plant pleiotropic drug resistance transporter expressed in Nicotiana tabacum BY-2 suspension cells.

    Science.gov (United States)

    Toussaint, Frédéric; Pierman, Baptiste; Bertin, Aurélie; Lévy, Daniel; Boutry, Marc

    2017-05-04

    Pleiotropic drug resistance (PDR) transporters belong to the ABCG subfamily of ATP-binding cassette (ABC) transporters and are involved in the transport of various molecules across plasma membranes. During evolution, PDR genes appeared independently in fungi and in plants from a duplication of a half-size ABC gene. The enzymatic properties of purified PDR transporters from yeast have been characterized. This is not the case for any plant PDR transporter, or, incidentally, for any purified plant ABC transporter. Yet, plant PDR transporters play important roles in plant physiology such as hormone signaling or resistance to pathogens or herbivores. Here, we describe the expression, purification, enzymatic characterization and 2D analysis by electron microscopy of NpABCG5/NpPDR5 from Nicotiana plumbaginifolia , which has been shown to be involved in the plant defense against herbivores. We constitutively expressed NpABCG5/NpPDR5, provided with a His-tag in a homologous system: suspension cells from Nicotiana tabacum (Bright Yellow 2 line). NpABCG5/NpPDR5 was targeted to the plasma membrane and was solubilized by dodecyl maltoside and purified by Ni-affinity chromatography. The ATP-hydrolyzing specific activity (27 nmol min -1  mg -1 ) was stimulated seven-fold in the presence of 0.1% asolectin. Electron microscopy analysis indicated that NpABCG5/NpPDR5 is monomeric and with dimensions shorter than those of known ABC transporters. Enzymatic data (optimal pH and sensitivity to inhibitors) confirmed that plant and fungal PDR transporters have different properties. These data also show that N. tabacum suspension cells are a convenient host for the purification and biochemical characterization of ABC transporters. © 2017 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society.

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

    OpenAIRE

    Friedman, Milton

    1992-01-01

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

  19. Efficacy and safety of nanohybrids comprising silver nanoparticles and silicate clay for controlling Salmonella infection

    Directory of Open Access Journals (Sweden)

    Bau IJ

    2012-05-01

    Full Text Available Shu-Her Chiao,1* Siou-Hong Lin,1* Ching-I Shen,2* Jiunn-Wang Liao,3 I-Jiuan Bau,1 Jiun-Chiou Wei,4 Li-Ping Tseng,1 Shan-hui Hsu,4 Ping-Shan Lai,2 Shinn-Zong Lin,5–7 Jiang-Jen Lin,4 Hong-Lin Su,1,8 1Department of Life Sciences, Agricultural Biotechnology Center, National Chung Hsing University, 2Department of Chemistry, Agricultural Biotechnology Center, National Chung Hsing University, 3Graduate Institute of Veterinary Pathobiology, Agricultural Biotechnology Center, National Chung Hsing University, Taichung, Taiwan; 4Institute of Polymer Science and Engineering, National Taiwan University, Taipei, Taiwan; 5Center for Neuropsychiatry, China Medical University and Hospital, Taichung, Taiwan; 6Department of Neurosurgery, China Medical University Beigan Hospital, Yunlin, Taiwan; 7Graduate Institute of Immunology, China Medical University, Taichung, Taiwan; 8Department of Physical Therapy, China Medical University, Taichung, Taiwan*These three authors contributed equallyAbstract: Developing effective and safe drugs is imperative for replacing antibiotics and controlling multidrug-resistant microbes. Nanoscale silicate platelet (NSP and its nanohybrid, silver nanoparticle/NSP (AgNP/NSP, have been developed, and the nanohybrids show a strong and general antibacterial activity in vitro. Here, their efficacy for protecting Salmonella-infected chicks from fatality and septicemia was evaluated. Both orally administrated NSP and AgNP/NSP, but not AgNPs alone, effectively reduced the systemic Salmonella infection and mortality. In addition, quantitative Ag analyses demonstrated that Ag deposition from AgNP/NSP in the intestines was less than that from conventional AgNPs, indicating that the presence of NSP for immobilizing AgNPs reduced Ag accumulation in tissue and improved the safety of AgNPs. These in vivo results illustrated that both NSP and AgNP/NSP nanohybrid represent potential agents for controlling enteric bacterial infections.Keywords: silver

  20. Enhanced antimicrobial efficacy of thermal-reduced silver nanoparticles supported by titanium dioxide.

    Science.gov (United States)

    Chen, Yen-Chi; Yu, Kuo-Pin

    2017-06-01

    The antimicrobial efficacy of silver nanoparticles (AgNPs) is influenced by many factors, including the particle size, AgNP oxidation state and support materials. In this study, AgNPs are synthesized and supported by two types of TiO 2 powders (P25 and Merck TiO 2 ) using two heat-treatment temperatures (120 and 200°C). The formation of well-dispersed AgNPs with diameters ranging from 3.2 to 5.7nm was confirmed using transmission electron microscopy. X-ray photoelectron spectroscopy and X-ray diffraction indicated that the majority of the AgNPs were reduced from Ag + to Ag 0 at 200°C. The AgNP antimicrobial activity was determined by the zone of inhibition against three fungi, A. niger, P. spinulosum and S. chartarum, and two bacteria, E. coli (Gram-negative) and S. epidermidis (Gram-positive). The antimicrobial activity of metallic AgNPs was more pronounced than that of silver nitrate and some antimicrobial drugs. The AgNPs exhibited optimal antimicrobial efficacy when the AgNP dispersion on the surface of TiO 2 was in the region between 0.2 and 0.7μg-Ag/m 2 . The minimum (critical) AgNP concentrations needed to inhibit the growth of bacteria (E. coli) and fungi (A. niger) were 13.48 and 25.4μg/mL, respectively. The results indicate that AgNPs/TiO 2 nanocomposites are a promising disinfectant against both bacteria and fungi. Copyright © 2017 Elsevier B.V. All rights reserved.