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Sample records for effect silver additive

  1. The effect of silver (Ag) addition to mechanical and electrical properties of copper alloy (Cu) casting product

    Science.gov (United States)

    Felicia, Dian M.; Rochiem, R.; Laia, Standley M.

    2018-04-01

    Copper have good mechanical properties and good electrical conductivities. Therefore, copper usually used as electrical components. Silver have better electrical conductivities than copper. Female contact resistor is one of the electrical component used in circuit breaker. This study aims to analyze the effect of silver addition to hardness, strength, and electric conductivity properties of copper alloy. This study uses variation of 0; 0.035; 0.07; 0.1 wt. % Ag (silver) addition to determine the effect on mechanical properties and electrical properties of copper alloy through sand casting process. Modelling of thermal analysis and structural analysis was calculated to find the best design for the sand casting experiments. The result of Cu-Ag alloy as cast will be characterized by OES test, metallography test, Brinell hardness test, tensile test, and LCR meter test. The result of this study showed that the addition of silver increase mechanical properties of Cu-Ag. The maximum hardness value of this alloy is 83.1 HRB which is Cu-0.01 Ag and the lowest is 52.26 HRB which is pure Cu. The maximum strength value is 153.2 MPa which is Cu-0.07 Ag and the lowest is 94.6 MPa which is pure Cu. Silver addition decrease electrical properties of this alloy. The highest electric conductivity is 438.98 S/m which is pure Cu and the lowest is 52.61 S.m which is Cu-0.1 Ag.

  2. Effect of silver addition on the properties of combustion synthesized nanocrystalline LiCoO2

    International Nuclear Information System (INIS)

    Ghosh, Paromita; Mahanty, S.; Basu, R.N.

    2008-01-01

    Nanocrystalline (∼50 nm) LiCoO 2 powders containing 0-10 mol% of Ag have been prepared by combustion synthesis using citrate-nitrate combustion route. Thermal analyses show a sharp decomposition of the gel at ∼177 deg. C for pristine LiCoO 2 . With addition of silver, the decomposition becomes sluggish and it completes only above 430 deg. C. X-ray powder diffraction analyses show an increase in lattice parameter, c, with increasing Ag content suggesting the occupation of Ag within LiCoO 2 interlayer spacings. Transmission electron microscopy indicates diffusion of Ag into LiCoO 2 grains. It has been observed that adding 1.0 mol% silver increases the room temperature electrical conductivity by more than two orders of magnitude (1.5 x 10 -3 S cm -1 ). Galvanostatic charge-discharge profiles of coin cells fabricated with the synthesized powders show a two-fold enhancement in the discharge capacity for 1.0 mol% Ag-added LiCoO 2 cathode (140 mAh g -1 ) compared to that for pristine LiCoO 2 (70 mAh g -1 )

  3. Effect of silver additive on physicochemical properties of hydroxyapatite applied to reconstructive surgery

    Energy Technology Data Exchange (ETDEWEB)

    Zhuk, I. V., E-mail: zhukiv1993@mail.ru; Rasskazova, L. A., E-mail: ly-2207@mail.ru; Korotchenko, N. M., E-mail: korotch@mail.ru [National Research Tomsk State University 36, Lenina Avenue, Tomsk, 634050 (Russian Federation)

    2015-11-17

    The effect of silver adding to hydroxyapatite (HA) in its solubility in physiological solution and biological activity was investigated. Samples of HA containing silver (AgHA) obtained by liquid-phase method in the conditions of microwave exposure. Solubility (C{sub Ca}{sup 2+}·10{sup 3}, mol/l) of the powders AgHA was determined by chemical methods according trilonometric titration of the calcium ions in physiological solution at 25 and 37 °C. To investigate the biological activity of the samples, a series of experiments on the formation of the calcium-phosphate layer on the surface of the SBF-solution at 37 °C for 28 days. Electronic micrographs of samples taken at the end of each 7 days of the experiment, indicate the formation of calcium-phosphate layer (CPL) in the samples, the kinetics of which is shown as a function of cumulative concentrations of calcium and magnesium ions from time.

  4. Synergistic and additive effect of oregano essential oil and biological silver nanoparticles against multidrug-resistant bacterial strains

    Directory of Open Access Journals (Sweden)

    Sara eScandorieiro

    2016-05-01

    Full Text Available Bacterial resistance to conventional antibiotics has become a clinical and public health problem, making therapeutic decisions more challenging. Plant compounds and nanodrugs have been proposed as potential antimicrobial alternatives. Studies have shown that oregano (Origanum vulgare essential oil (OEO and silver nanoparticles have potent antibacterial activity, also against multidrug-resistant strains; however, the strong organoleptic characteristics of OEO and the development of resistance to these metal nanoparticles can limit their use. This study evaluated the antibacterial effect of a two-drug combination of biologically synthesized silver nanoparticles (bio-AgNP, produced by Fusarium oxysporum, and OEO against Gram-positive and Gram-negative bacteria, including multidrug-resistant strains. OEO and bio-AgNP showed bactericidal effects against all seventeen strains tested, with minimal inhibitory concentrations (MIC ranging from 0.298 to 1.193 mg/mL and 62.5 to 250 µM, respectively. Time-kill curves indicated that OEO acted rapidly (within 10 min, while the metallic nanoparticles took 4 h to kill Gram-negative bacteria and 24 h to kill Gram-positive bacteria. The combination of the two compounds resulted in a synergistic or additive effect, reducing their MIC values and reducing the time of action compared to bio-AgNP used alone, i.e., 20 min for Gram-negative bacteria and 7 h for Gram-positive bacteria. Scanning electron microscopy (SEM revealed similar morphological alterations in Staphylococcus aureus (non-methicillin-resistant S. aureus, non-MRSA cells exposed to three different treatments (OEO, bio-AgNP and combination of the two, which appeared cell surface blebbing. Individual and combined treatments showed reduction in cell density and decrease in exopolysaccharide matrix compared to untreated bacterial cells. It indicated that this composition have an antimicrobial activity against S. aureus by disrupting cells. Both compounds

  5. Synergistic and Additive Effect of Oregano Essential Oil and Biological Silver Nanoparticles against Multidrug-Resistant Bacterial Strains.

    Science.gov (United States)

    Scandorieiro, Sara; de Camargo, Larissa C; Lancheros, Cesar A C; Yamada-Ogatta, Sueli F; Nakamura, Celso V; de Oliveira, Admilton G; Andrade, Célia G T J; Duran, Nelson; Nakazato, Gerson; Kobayashi, Renata K T

    2016-01-01

    Bacterial resistance to conventional antibiotics has become a clinical and public health problem, making therapeutic decisions more challenging. Plant compounds and nanodrugs have been proposed as potential antimicrobial alternatives. Studies have shown that oregano (Origanum vulgare) essential oil (OEO) and silver nanoparticles have potent antibacterial activity, also against multidrug-resistant strains; however, the strong organoleptic characteristics of OEO and the development of resistance to these metal nanoparticles can limit their use. This study evaluated the antibacterial effect of a two-drug combination of biologically synthesized silver nanoparticles (bio-AgNP), produced by Fusarium oxysporum, and OEO against Gram-positive and Gram-negative bacteria, including multidrug-resistant strains. OEO and bio-AgNP showed bactericidal effects against all 17 strains tested, with minimal inhibitory concentrations (MIC) ranging from 0.298 to 1.193 mg/mL and 62.5 to 250 μM, respectively. Time-kill curves indicated that OEO acted rapidly (within 10 min), while the metallic nanoparticles took 4 h to kill Gram-negative bacteria and 24 h to kill Gram-positive bacteria. The combination of the two compounds resulted in a synergistic or additive effect, reducing their MIC values and reducing the time of action compared to bio-AgNP used alone, i.e., 20 min for Gram-negative bacteria and 7 h for Gram-positive bacteria. Scanning electron microscopy (SEM) revealed similar morphological alterations in Staphylococcus aureus (non-methicillin-resistant S. aureus, non-MRSA) cells exposed to three different treatments (OEO, bio-AgNP and combination of the two), which appeared cell surface blebbing. Individual and combined treatments showed reduction in cell density and decrease in exopolysaccharide matrix compared to untreated bacterial cells. It indicated that this composition have an antimicrobial activity against S. aureus by disrupting cells. Both compounds showed very low

  6. Study of Supported Nickel Catalysts Prepared by Aqueous Hydrazine Method. Hydrogenating Properties and Hydrogen Storage: Support Effect. Silver Additive Effect

    International Nuclear Information System (INIS)

    Wojcieszak, R.

    2006-06-01

    We have studied Ni or NiAg nano-particles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports (γ-Al 2 O 3 , amorphous or crystallized SiO 2 , Nb 2 O 5 , CeO 2 and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N 2 , FTIR and FTIR-Pyridine, TEM, STEM, EDS, H 2 -TPR, H 2 -adsorption, H 2 -TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO 2 or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0.53%/30 bars), probably through the hydrogen spillover effect. (author)

  7. Effect of silver addition on the mechanical and field trapping properties of Gd-Ba-Cu-O bulk superconductors

    CERN Document Server

    Nariki, S; Matsui, M; Murakami, M

    2002-01-01

    The effect of Ag addition on the microstructure and the mechanical and field trapping properties of Gd-Ba-Cu-O bulk superconductor has been investigated. The single grain Gd-Ba-Cu-O bulk superconductors 32 mm in diameter were fabricated with 0-30 mass%Ag/sub 2/O additions by the melt growth method under controlled oxygen partial pressure of 1.0%. From microscopic observations, it was found that the macro- cracks in the a-b plane decreased with Ag addition. The three-point bending test showed that the average strength of Ag-free bulk was 69 MPa at room temperature, while the strength was dramatically improved to 110-115 MPa with 10-30 mass%Ag/sub 2/O additions. The trapped magnetic field of Ag-free bulk sample was 1.3 T at 77 K. The trapped field of bulk Gd-Ba-Cu-O samples with 10-20 mass%Ag/sub 2/O exhibited high values of 1.8-2.0 T at 77 K. However, the trapped field of the sample with 30 mass%Ag/sub 2/O addition was lowered to 1.1 T with decreasing the critical current density. The trapped field of Ag- adde...

  8. 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.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  10. A new humic acid remedy with addition of silver nanoparticles

    OpenAIRE

    GP Alexandrova; G Dolmaa; E Enkhbadral; GL Grishenko; Sh Tserenpil; BG Sukhov; D Regdel; BA Trofimov

    2014-01-01

    Previously known biogenic stimulator humic acid (HA) was the subject of this current study and HA based new remediation was developed by addition of silver (Ag) nanoparticles in its macromolecule. Extracted HA from a healing mud was characterized and used as reducing agent for Ag ion as well as a stabilizer for the formed Ag nanoparticles. The properties of the obtained hybrid composite were examined by XRD, UV and FTIR spectroscopic techniques. The diameter of the nanoparticles in the HA pol...

  11. Antituberculous effect of silver nanoparticles

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  12. Antituberculous effect of silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kreytsberg, G N; Gracheva, I E [Limited Liability Company ' Scientific and Production Association (NPO)' Likom' , 150049, Yaroslavl, Magistralnaya str., 32 (Russian Federation); Kibrik, B S [Yaroslavl State Medical Academy Russia, 150000, Yaroslavl, Revolutsionnaya str., 5 (Russian Federation); Golikov, I V, E-mail: likomm@yaroslavl.ru [Yaroslavl State Technical University Russia, 150023, Yaroslavl, Moskovskiy avenue, 88 (Russian Federation)

    2011-04-01

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

  13. Dendritic silver nanostructures obtained via one-step electrosynthesis: effect of nonanesulfonic acid and polyvinylpyrrolidone as additives on the analytical performance for hydrogen peroxide sensing

    Energy Technology Data Exchange (ETDEWEB)

    Guadagnini, Lorella, E-mail: lorella.guadagnini2@unibo.it; Ballarin, Barbara, E-mail: barbara.ballarin@unibo.it; Tonelli, Domenica [University of Bologna, Department of Industrial Chemistry ' Toso Montanari' (Italy)

    2013-10-15

    The electrochemical deposition of silver nanodendrites (AgNDs) on pure graphite sheet (PGS) electrodes, both in the absence of surfactant/templates and in the presence of 1-nonanesulfonic acid (NS) or polyvinylpyrrolidone (PVP) additives, is reported. The synthesis carried out without additives and with NS produced a bigger amount of large size AgNDs (dimension of 1-5 {mu}m), with scarce influence played by NS, while the deposition with PVP favoured the formation of smaller spherical particles (with average diameter below 150 nm). The performances of the electrodes towards the electroreduction of H{sub 2}O{sub 2} were investigated by chronoamperometry at -0.4 V and at more cathodic applied potentials (-0.6 and -0.8 V). The electrodes fabricated without additives and in the presence of NS displayed similar performances, while those fabricated with PVP exhibited significantly lower sensitivity. This suggests that AgNDs present enhanced electrocatalytic activity in respect to the spherical aggregates, since the Ag amount deposited on PGS was practically the same. The best amperometric responses among those recorded at -0.4 V in PBS (pH 6.7) exhibited a linear range extending from 0.1 to 3.5 mM, a detection limit of about 20 {mu}M and a sensitivity close to 200 mA M{sup -1} cm{sup -2}. The proposed electrodes display sensitivities which are markedly better than those reported in the literature for similar Ag-based sensors.

  14. A new humic acid remedy with addition of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    GP Alexandrova

    2014-09-01

    Full Text Available Previously known biogenic stimulator humic acid (HA was the subject of this current study and HA based new remediation was developed by addition of silver (Ag nanoparticles in its macromolecule. Extracted HA from a healing mud was characterized and used as reducing agent for Ag ion as well as a stabilizer for the formed Ag nanoparticles. The properties of the obtained hybrid composite were examined by XRD, UV and FTIR spectroscopic techniques. The diameter of the nanoparticles in the HA polymer was up to 8.6 nm and they were identified to be metallic Ag.DOI: http://dx.doi.org/10.5564/mjc.v13i0.151 Mongolian Journal of Chemistry Vol.13 2012: 7-11

  15. Silver-Assisted Synthesis of Gold Nanorods: the Relation between Silver Additive and Iodide Impurities.

    Science.gov (United States)

    Jessl, Sarah; Tebbe, Moritz; Guerrini, Luca; Fery, Andreas; Alvarez-Puebla, Ramon A; Pazos-Perez, Nicolas

    2018-04-17

    Seed-mediated methods employing cetyltrimethylammonium bromide (CTAB) as a surfactant, and silver salts as additives, are the most common synthetic strategies for high-yield productions of quality Au nanorods. However, the mechanism of these reactions is not yet fully understood and, importantly, significant lab-to-lab reproducibility issues still affect these protocols. In this study, the direct correlation between the hidden content of iodide impurities in CTAB reagents, which can drastically differ from different suppliers or batches, and the optimal concentration of silver required to maximize the nanorods yield is demonstrated. As a result, high-quality nanorods are obtained at different iodide contents. These results are interpreted based on the different concentrations of CTAB and cetyltrimethylammonium iodide (CTAI) complexes with Ag + and Au + metal ions in the growth solution, and their different binding affinity and reduction potential on distinct crystallographic planes. Notably, the exhaustive conversion of CTAI-Au + to CTAI-Ag + appears to be the key condition for maximizing the nanorod yield. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 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.

  17. Low molecular weight compounds as effective dispersing agents in the formation of colloidal silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Natsuki, Jun; Natsuki, Toshiaki, E-mail: natsuki@shinshu-u.ac.jp; Abe, Takao [Shinshu University, Faculty of Textile Science and Technology (Japan)

    2013-03-15

    A convenient method to synthesize uniform, well-dispersed colloidal silver nanoparticles is described. Aldonic acid or {alpha}-hydroxy acid compounds of low molecular weight are used instead of polymeric compounds as dispersing agents to prepare silver nanoparticles. The size, conformation, and electrical conductivity of the silver nanoparticles, and the effect and function of the dispersing agents are investigated in detail. Using these low molecular weight compounds as dispersing agents, silver nanoparticles with a diameter of 10 nm or less and high electrical conductivity can be obtained. In addition, this procedure allows silver nanoparticles to be sintered at 150 Degree-Sign C, which is lower than that required for silver nanoparticle formulation using polymeric compounds (200 Degree-Sign C). The silver nanoparticles produced by this process can be used to prepare various inks and to manufacture electronic circuits. It is found that low molecular weight compounds are more effective dispersing agents than polymeric compounds in the formation of silver nanoparticles.

  18. Colloidal silver fabrication using the spark discharge system and its antimicrobial effect on Staphylococcus aureus.

    Science.gov (United States)

    Tien, Der-Chi; Tseng, Kuo-Hsiung; Liao, Chih-Yu; Tsung, Tsing-Tshih

    2008-10-01

    Nanoscale techniques for silver production may assist the resurgence of the medical use of silver, especially given that pathogens are showing increasing resistance to antibiotics. Traditional chemical synthesis methods for colloidal silver (CS) may lead to the presence of toxic chemical species or chemical residues, which may inhibit the effectiveness of CS as an antibacterial agent. To counter these problems a spark discharge system (SDS) was used to fabricate a suspension of colloidal silver in deionized water with no added chemical surfactants. SDS-CS contains both metallic silver nanoparticles (Ag(0)) and ionic silver forms (Ag(+)). The antimicrobial affect of SDS-CS on Staphylococcus aureus was studied. The results show that CS solutions with an ionic silver concentration of 30 ppm or higher are strong enough to destroy S. aureus. In addition, it was found that a solution's antimicrobial potency is directly related to its level of silver ion concentration.

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

    Science.gov (United States)

    Rajaeian, Babak; Allard, Sébastien; Joll, Cynthia; Heitz, Anna

    2018-07-01

    Silver impregnated activated carbon (SIAC) has been found to be effective in mitigating the formation of brominated-disinfection by products during drinking water treatment. However, there are still uncertainties regarding its silver leaching properties, and strategies for the prevention of silver leaching have remained elusive. This study focused on the evaluation of one type of commercially available SIAC for its ability to remove bromide while minimising silver leaching from the material. Both synthetic and real water matrices were tested. Depending on solution pH, it was found that changing the surface charge properties of SIAC, as measured by the point of zero charge pH, can result in additional bromide removal while minimising the extent of silver leaching. To better understand the mechanism of silver leaching from the SIAC, eight preconditioning environments, i.e. variable pH and ionic strength were tested for a fixed amount of SIAC and two preconditioning environments were selected for a more detailed investigation. Experiments carried out in synthetic water showed that preconditioning at pH 10.4 did not deteriorate the capacity of SIAC to remove bromide, but significantly decreased the release of silver in the form of ionic silver (Ag + ), silver bromide (AgBr) and silver chloride (AgCl) from 40% for the pristine to 3% for the treated SIAC. This was confirmed using a groundwater sample. These results suggest that preconditioned SIAC has the potential to be an effective method for bromide removal with minimised silver leaching in a long-term field application for drinking water production. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. The Analysis of Silver Nanoparticles After the Manipulation of Synthesis Parameters and with the Addition of Potassium 2-(9-Carboxy-1-Octylnonylsulfanyl)-Malonate

    International Nuclear Information System (INIS)

    Chin, S.Y.; Hakam, M.A.O.; Goh, S.C.; Yarmo, M.A.

    2011-01-01

    This research aimed to synthesize and characterize silver nanoparticles by manipulating the parameters involved in stabilizing the particles. The silver nanoparticles in this research were synthesized by reduction process of silver nitrate (AgNO 3 ) with sodium borohydrate (NaBH 4 ) as the reducing agent. The addition of potassium 2- (9-carboxy-1-octylnonylsulfanyl)-malonate into silver nanoparticles solution functioned as a stabilizing agent. The parameters involved in this research were the effect of time towards stability of silver nanoparticles, the effect of addition of potassium 2-(9-carboxy-1-octylnonylsulfanyl)- malonate and the pH level effect towards the synthesized silver nanoparticles. Based on the results obtained from Transmission Electron Microscopy (TEM), we have observed that the incorporation of potassium 2-(9-carboxy-1- octyl-nonanesulfonyl)-malonate as the stabilizing agent can prevent the agglomeration of silver nanoparticles within 16 days which is a breakthrough for the synthesis of silver nanoparticles by using sodium borohydride. The micrograph showed that the size of silver nanoparticles synthesized were within the range of 1.5 nm to 8.3 nm. In addition to that, Dynamic Light Scattering (DLS) technique was used in this research to measure the average size of the silver nanoparticles which stabilized with potassium 2-(9-carboxy-1-octyl-nonanesulfonyl)-malonate. X-Ray Diffraction (XRD) analysis was carried out to view the effect of manipulated pH level on crystalline silver nanoparticles structure. The XRD diffractogram showed the diffraction peaks which can be indexed to planes of face- centered cubic (fcc) of pure silver. (author)

  1. Antibacterial effect of PEO coating with silver on AA7075

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-06-01

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

  2. Antibacterial effect of PEO coating with silver on AA7075

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  3. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized using polyol method

    Energy Technology Data Exchange (ETDEWEB)

    Junaidi, E-mail: junaidi.1982@fmipa.unila.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Department of Physics, Lampung University, Bandar Lampung (Indonesia); Yunus, Muhammad, E-mail: muhammad.yunus@mail.ugm.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Triyana, Kuwat, E-mail: triyana@ugm.ac.id; Harsojo,, E-mail: harsojougm@ugm.ac.id; Suharyadi, Edi, E-mail: esuharyadi@ugm.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Nanomaterials Research Group, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia)

    2016-04-19

    We report our investigation on the effect of chloride ions on controlling the shapes and properties of silver nanorods (AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as a salt precursor and performed at the oil bath temperature of 140°C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorods were characterized using SEM and XRD. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline of silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorods decreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

  4. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized by polyol method

    International Nuclear Information System (INIS)

    Junaidi; Triyana, Kuwat; Harsojo,; Suharyadi, Edi

    2016-01-01

    We report our investigation on the effect of chloride ions oncontrolling the shapes and properties of silver nanorods(AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as asalt precursor and performed at the oilbath temperature of 140 °C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorodswere characterized using UV-VIS, XRD, SEM and TEM. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorodsdecreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

  5. Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized using polyol method

    International Nuclear Information System (INIS)

    Junaidi; Yunus, Muhammad; Triyana, Kuwat; Harsojo,; Suharyadi, Edi

    2016-01-01

    We report our investigation on the effect of chloride ions on controlling the shapes and properties of silver nanorods (AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as a salt precursor and performed at the oil bath temperature of 140°C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorods were characterized using SEM and XRD. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline of silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorods decreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

  6. Antibacterial Behavior of Additively Manufactured Porous Titanium with Nanotubular Surfaces Releasing Silver Ions.

    Science.gov (United States)

    Amin Yavari, S; Loozen, L; Paganelli, F L; Bakhshandeh, S; Lietaert, K; Groot, J A; Fluit, A C; Boel, C H E; Alblas, J; Vogely, H C; Weinans, H; Zadpoor, A A

    2016-07-13

    Additive manufacturing (3D printing) has enabled fabrication of geometrically complex and fully interconnected porous biomaterials with huge surface areas that could be used for biofunctionalization to achieve multifunctional biomaterials. Covering the huge surface area of such porous titanium with nanotubes has been already shown to result in improved bone regeneration performance and implant fixation. In this study, we loaded TiO2 nanotubes with silver antimicrobial agents to equip them with an additional biofunctionality, i.e., antimicrobial behavior. An optimized anodizing protocol was used to create nanotubes on the entire surface area of direct metal printed porous titanium scaffolds. The nanotubes were then loaded by soaking them in three different concentrations (i.e., 0.02, 0.1, and 0.5 M) of AgNO3 solution. The antimicrobial behavior and cell viability of the developed biomaterials were assessed. As far as the early time points (i.e., up to 1 day) are concerned, the biomaterials were found to be extremely effective in preventing biofilm formation and decreasing the number of planktonic bacteria particularly for the middle and high concentrations of silver ions. Interestingly, nanotubes not loaded with antimicrobial agents also showed significantly smaller numbers of adherent bacteria at day 1, which may be attributed to the bactericidal effect of high aspect ratio nanotopographies. The specimens with the highest concentrations of antimicrobial agents adversely affected cell viability at day 1, but this effect is expected to decrease or disappear in the following days as the rate of release of silver ions was observed to markedly decrease within the next few days. The antimicrobial effects of the biomaterials, particularly the ones with the middle and high concentrations of antimicrobial agents, continued until 2 weeks. The potency of the developed biomaterials in decreasing the number of planktonic bacteria and hindering the formation of biofilms make

  7. Effect of silver and indium addition on mechanical properties and indentation creep behavior of rapidly solidified Bi–Sn based lead-free solder alloys

    International Nuclear Information System (INIS)

    Shalaby, Rizk Mostafa

    2013-01-01

    Mechanical properties and indentation creep of the melt-spun process Bi–42 wt%Sn, Bi–40 wt%Sn–2 wt%In, Bi–40 wt%Sn–2 wt%Ag and Bi–38 wt%Sn–2 wt%In–2 wt%Ag were studied by dynamic resonance technique and Vickers indentation testing at room temperature and compared to that of the traditional Sn–37 wt%Pb eutectic alloy. The results show that the structure of Bi–42 wt%Sn alloy is characterized by the presence of rhombohedral Bi and body centered tetragonal β-Sn. The two ternary alloys exhibit additional constituent phases of intermetallic compounds SnIn 19 for Bi–40 wt%Sn–2 wt%In and ε-Ag 3 Sn for Bi–40 wt%Sn–2 wt%Ag alloys. Attention has been paid to the role of intermetallic compounds on mechanical and creep behavior. The In and Ag containing solder alloy exhibited a good combination of higher creep resistance, good mechanical properties and lower melting temperature as compared with Pb–Sn eutectic solder alloy. This was attributed to the strengthening effect of Bi as a strong solid solution element in the Sn matrix and formation of intermetallic compounds β-SnBi, ε-Ag 3 Sn and InSn 19 which act as both strengthening agent and grain refiner in the matrix of the material. Addition of In and Ag decreased the melting temperature of Bi–Sn lead-free solder from 143 °C to 133 °C which was possible mainly due to the existence of InSn 19 and Ag 3 Sn intermetallic compounds. Elastic constants, internal friction and thermal properties of Bi–Sn based alloys have been studied and analyzed.

  8. Synergistic antibacterial effects of β-lactam antibiotic combined with silver nanoparticles

    Science.gov (United States)

    Li, Ping; Li, Juan; Wu, Changzhu; Wu, Qingsheng; Li, Jian

    2005-09-01

    The bactericidal action of silver (0) nanoparticles and amoxicillin on Escherichia coli is studied, respectively. Increasing concentration of both amoxicillin (0-0.525 mg ml-1) and silver nanoparticles (0-40 µg ml-1) showed a higher antibacterial effect in Luria-Bertani (LB) medium. Escherichia coli cells have different bactericidal sensitivity to them. When amoxicillin and silver nanoparticles are combined, it results in greater bactericidal efficiency on Escherichia coli cells than when they were applied separately. Dynamic tests on bacterial growth indicated that exponential and stationary phases are greatly decreased and delayed in the synergistic effect of amoxicillin and silver nanoparticles. In addition, the effect induced by a preincubation with silver nanoparticles is examined. The results show that solutions with more silver nanoparticles have better antimicrobial effects. One hypothesized mechanism is proposed to explain this phenomenon.

  9. Silver diffusion and isotope effect in silver rubidium iodide

    International Nuclear Information System (INIS)

    Arzigian, J.S.

    1980-01-01

    The diffusion coefficient of silver in RbAg 4 I 5 was measured in both superionic phases using radiotracer Ag-110m and serial sectioning with a low temperature sectioning apparatus. The activation energies for diffusion in alpha-RbAg 4 I 5 and beta-RbAg 4 I 5 , respectively, are 0.11 +- 0.01 eV and 0.20 +- 0.04 eV. An isotope effect for diffusion was also measured in both superionic phases. Ag-105 and Ag-110m radioisotopes were used with gamma spectroscopy and energy discrimination. The effect is small, with no significant temperature variation, with the value at 333 0 K being 0.12 +- 0.01. The second-order phase transition at 208 0 K has a small effect, if any, on the magnitude of the effect. The data suggest that a highly cooperative transport mechanism is responsible for the unusually high values of both the conductivity and diffusion coefficient. Although it is not possible to deduce the particular mechanism involved, theories inolving ionic polarons, or cooperative motion, such as crowdions or solitons, seem consistent with the observed results

  10. Solvent-Free Synthesis of Silver-Nanoparticles and their Use as Additive in Poly (Dicyclopentadiene)

    International Nuclear Information System (INIS)

    Abbas, M.; Kienberger, J.

    2013-01-01

    A solvent-free environmentally benign synthesis of oleylamine capped silver nanoparticles is presented. Upon heating 10 equivalents of oleylamine and silver nitrate at 165 degree C for 30 min followed by a precipitation step using ethanol as the precipitant particles characterized by an Z-average diameter of 63 nm were obtained. Dried particles can be easily redispersed in unpolar solvents or monomers, which pave the way for using them as an antimicrobial additive in polymeric materials. In particular, newly prepared Ag-particles were dispersed in dicyclopentadiene and the mixture was cured using ring opening metathesis polymerization yielding an antimicrobially equipped duroplastic material. (author)

  11. Antibacterial Effect of Silver Diamine Fluoride on Cariogenic Organisms.

    Science.gov (United States)

    Lou, Yali; Darvell, Brain W; Botelho, Michael G

    2018-05-01

    To screen the possible antimicrobial activity of a range of clinically used, silver-based compounds on cariogenic organisms: silver diamine fluoride (SDF), silver fluoride, and silver nitrate. Preliminary screening disk-diffusion susceptibility tests were conducted on Mueller-Hinton agar plates inoculated with Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces naeslundii, organisms known to be cariogenic. In order to identify which component of the silver compounds was responsible for any antibacterial (AB) effect, and to provide controls, the following were also investigated at high and low concentrations: sodium fluoride, ammonium fluoride, ammonium chloride, sodium fluoride, sodium chloride, and sodium nitrate, as well as deionized water as control. A volume of 10 pL of a test solution was dispensed onto a paper disk resting on the inoculated agar surface, and the plate incubated anaerobically at 37°C for 48 hours. The zones of inhibition were then measured. Silver diamine fluoride, silver fluoride, silver nitrate, and ammonium fluoride had significant AB effect (p effect at low concentration; the remaining other compounds had no effect. Silver ions appear to be the principal AB agent at both high and low concentration; fluoride ions only have an AB effect at high concentration, while ammonium, nitrate, chloride and sodium ions have none. The anticaries effect of topical silver solutions appears restricted to that of the silver ions. Silver compounds, such as SDF, silver fluoride, and silver nitrate have AB effect against cariogenic organisms and these may have clinical impact in arresting or preventing dental decay. Sodium fluoride did not have AB effect under the conditions tested.

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

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

  13. TERATOGENIC EFFECTS OF SILVER NANOPARTICLES: GROSS ANOMALIES

    OpenAIRE

    Jyoti Prakash; Rajniti; Deepika; Royana

    2015-01-01

    BACK GROUND: Prenatal exposure of AgNPs can induces devastative and detrimental effect in the organogenesis period of the developing embryos and foetuses. Organogenesis period is highly condemnatory and persuadable. Any injury to embryo during this period leads to dysmorphogenesis or even death AIM: The present study means to evaluate the gross anomalies on developing f o etus subsequent to silver nanoparticle ingestion during the gestational period. ...

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

    International Nuclear Information System (INIS)

    Wolter, D.

    1974-01-01

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

  15. Determine Minimum Silver Flake Addition to GCM for Iodine Loaded AgZ

    Energy Technology Data Exchange (ETDEWEB)

    Garino, Terry J.; Nenoff, Tina M.; Rodriguez, Mark A.

    2014-04-01

    The minimum amount of silver flake required to prevent loss of I{sub 2} during sintering in air for a SNL Glass Composite Material (GCM) Waste Form containing AgI-MOR (ORNL, 8.7 wt%) was determined to be 1.1 wt% Ag. The final GCM composition prior to sintering was 20 wt% AgI-MOR, 1.1 wt% Ag, and 80 wt% Bi-Si oxide glass. The amount of silver flake needed to suppress iodine loss was determined using thermo gravimetric analysis with mass spectroscopic off-gas analysis. These studies found that the ratio of silver to AgI-MOR required is lower in the presence of the glass than without it. Therefore an additional benefit of the GCM is that it serves to inhibit some iodine loss during processing. Alternatively, heating the AgI-MOR in inert atmosphere instead of air allowed for densified GCM formation without I{sub 2} loss, and no necessity for the addition of Ag. The cause of this behavior is found to be related to the oxidation of the metallic Ag to Ag{sup +} when heated to above ~300{degrees}C in air. Heating rate, iodine loading levels and atmosphere are the important variables that determine AgI migration and results suggest that AgI may be completely incorporated into the mordenite structure by the 550{degrees}C sintering temperature.

  16. Stability of colloidal silver nanoparticles trapped in lipid bilayer: effect of lecithin concentration and applied temperature.

    Science.gov (United States)

    Barani, Hossein; Montazer, Majid; Braun, Hans-Georg; Dutschk, Victoria

    2014-12-01

    The use of silver nanoparticle on various substrates has been widespread because of its good antibacterial properties that directly depend on the stability of the silver nanoparticles in a colloidal suspension. In this study, the colloidal solutions of the silver nanoparticles were synthesised by a simple and safe method by using lecithin as a stabilising agent and their stability was examined at various temperatures. The effect of the lecithin concentrations on the stability of the synthesised silver nanoparticles was examined from 25 to 80°C at 5°C intervals, by recording the changes in the UV-vis absorption spectra, the hydrodynamic diameter and the light scattering intensity of the silver nanoparticles. In addition, the morphology of the synthesised silver nanoparticles was investigated with the low-voltage scanning electron microscopy and transmission electron microscopy. The results indicated that increasing temperature caused different changes in the size of the stabilised and the unstabilised silver nanoparticles. The size of the stabilised silver nanoparticles reduced from 38 to 36 nm during increasing temperature, which confirmed good stability.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-01

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

  19. Synthesis and antimicrobial effects of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    S kheybari

    2010-09-01

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

  20. Silver Nanocluster Reparative Effect in Hernioplasty

    Directory of Open Access Journals (Sweden)

    Nikolay M. Anichkov

    2014-06-01

    Full Text Available Background: The acceleration of re-epithelialization and fibroblast differentiation were noted during the experiments with silver nanoclusters (SNs by interrupting the negative development of inflammation at the level of cytokines and promoting a positive course of reparative processes. The aim of this work was to elaborate the experimental model of prosthesis hernioplasty in subcutaneous and intraperitoneal locations of hernioprostheses with SNs, which allowed us to study the course of reparative reactions in all layers of the anterior abdominal wall. Material and Methods: We used a modified hernioprosthesis made from polyester fibers coated with a metal-polymer composition, including the stabilized SN in a concentration of 6.8 and 11.3 mg per 1 g of the hernioprosthesis mesh. During this research we used guinea pigs to study the in vivo tissue reactions. The clinical part of the study included the group of 212 patients who underwent removal of an inguinal hernia. We have identified various factors associated with infectious and toxic effects on the body by determining the level of the serum glutamate-pyruvate-transaminase (SGPT. Results: In implantation of the hernioprostheses, including the high concentration of SN in the laparotomy wound, the exudative component of the inflammation was weakly expressed. It was mostly the proliferative changes that took place. We did not find either CD8-positive type T lymphocytes or PAX5-positive type B activated cells in the exudate. Conclusion: Our research has shown that the use of hernioprostheses that include silver nanoclusters leads to the reduction of inflammation in the exudative phase and to a more favorable course of reparative processes.

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

    International Nuclear Information System (INIS)

    Shams, Gholamabbas; Ranjbar, Morteza; Amiri, Aliasghar

    2013-01-01

    The tremendous progress on nanoparticle research area has been made significant effects on the economy, society, and the environment. Silver nanoparticle is one of the most important particles in these categories. Silver nanoparticles can be converted to the heavy silver metal in water by oxidation. Moreover, in the high amounts of silver concentration, they will be accumulated in different parts of the plant. However, by changing the morphology of the plant, the production will be harmful for human consumptions. In this study, nano-powders with average 50 nm silver particles are mixed with deionized distilled water in a completely randomized design. Seven treatments with various concentrations of suspension silver nanoparticles were prepared and repeated in four different parts of the plant in a regular program of spraying. Samples were analyzed to study the growth indexes and concentration of silver in different parts of the plant. It was observed that with increasing concentration of silver nanoparticles on cucumber, the growth indexes (except pH fruit), and the concentration of silver heavy metal are increased significantly. The incremental concentration had the linear relationship with correlation coefficient 0.95 and an average of 0.617 PPM by increasing of each unit in one thousand concentration of nanosilver. Although, by increasing concentration of silver nanoparticles as spraying form, the plant morphological characteristics were improved, the concentration of silver heavy metal in various plant organs was increased. These results open a new pathway to consider the effect of nanoparticles on plant’s productions for human consumptions.

  2. The combined effects of Aloe vera gel and silver nanoparticles on wound healing in rats

    Directory of Open Access Journals (Sweden)

    Y. Yousefpoor

    2016-01-01

    Full Text Available Objective(s: This study was aimed at investigating the synergy effects of Aloe vera gel and silver nanoparticles on the healing rate of the cutting wounds. Materials and Methods: In order to determine the concentration of silver nanoparticles in Aloe vera gel, the MBC methods were applied on the most common bacteria infecting wounds, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa. The cutting wounds with Full-thickness skin were dorsally created on rats; then the rats were divided into 4 groups. The treatments groups included: mixture of Aloe vera gel and silver nanoparticles, Aloe vera gel alone and silver nanoparticles alone in addition to control groups. The treatment was carried out for 2 weeks and the size of the wound closures were measured by an image software analysis. Results:There was no significant difference (p

  3. Bacterial inhibiting surfaces caused by the effects of silver release and/or electrical field

    DEFF Research Database (Denmark)

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

    2008-01-01

    In this study, silver-palladium surfaces and silver-bearing stainless steels were designed and investigated focusing on electrochemical principles to form inhibiting effects on planktonic and/or biofilm bacteria in water systems. Silver-resistant Escherichia coli and silver-sensitive E. coli were...... silver ions release can occur from their Surfaces. For silver-bearing stainless steels, the inhibiting effect can only be explained by high local silver ions release. and can be limited or deactivated dependent on the specific environment. (c) 2008 Elsevier Ltd. All rights reserved....

  4. The immunomodulatory effects of titanium dioxide and silver nanoparticles.

    Science.gov (United States)

    Lappas, Courtney M

    2015-11-01

    Due to their characteristic physical, chemical and optical properties, titanium dioxide and silver nanoparticles are attractive tools for use in a wide range of applications. The use of nanoparticles for biological applications is, however, dependent upon their biocompatibility with living cells. Because of the importance of inflammation as a modulator of human health, the safe and efficacious in vivo use of titanium dioxide and silver nanoparticles is inherently linked to a favorable interaction with immune system cells. However, both titanium dioxide and silver nanoparticles have demonstrated potential to exert immunomodulatory and immunotoxic effects. Titanium dioxide and silver nanoparticles are readily internalized by immune system cells, may accumulate in peripheral lymphoid organs, and can influence multiple manifestations of immune cell activity. Although the factors influencing the biocompatibility of titanium dioxide and silver nanoparticles with immune system cells have not been fully elucidated, nanoparticle core composition, size, concentration and the duration of cell exposure seem to be important. Because titanium dioxide and silver nanoparticles are widely utilized in pharmaceutical, commercial and industrial products, it is vital that their effects on human health and immune system function be more thoroughly evaluated. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. 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

  6. 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

  7. The effect of a thin silver layer on the critical current of epitaxial YBCO films

    International Nuclear Information System (INIS)

    Polturak, E.; Koren, G.; Cohen, D.; Cohen, D.; Snapiro, I.

    1992-01-01

    We compare measurements of the critical current density of an epitaxial YBCO film with that of an identical film overlaid by a thin silver layer. We find that the presence of the silver lowers Tc of the film by about 1.5 K, which is two orders of magnitude larger than predicted by the theory of the proximity effect for our experimental conditions. In addition, J c of the Ag/YBCO film near Tc is also significantly lower than that of the bare YBCO film. We propose two alternate interpretations of this effect, one in terms of destabilization of the flux distribution in the film and the other making use of the effect of the silver on the Bean-Livingston surface barrier for the initial penetration of flux. The latter seems the more plausible explanation of our results. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-05-15

    The tremendous progress on nanoparticle research area has been made significant effects on the economy, society, and the environment. Silver nanoparticle is one of the most important particles in these categories. Silver nanoparticles can be converted to the heavy silver metal in water by oxidation. Moreover, in the high amounts of silver concentration, they will be accumulated in different parts of the plant. However, by changing the morphology of the plant, the production will be harmful for human consumptions. In this study, nano-powders with average 50 nm silver particles are mixed with deionized distilled water in a completely randomized design. Seven treatments with various concentrations of suspension silver nanoparticles were prepared and repeated in four different parts of the plant in a regular program of spraying. Samples were analyzed to study the growth indexes and concentration of silver in different parts of the plant. It was observed that with increasing concentration of silver nanoparticles on cucumber, the growth indexes (except pH fruit), and the concentration of silver heavy metal are increased significantly. The incremental concentration had the linear relationship with correlation coefficient 0.95 and an average of 0.617 PPM by increasing of each unit in one thousand concentration of nanosilver. Although, by increasing concentration of silver nanoparticles as spraying form, the plant morphological characteristics were improved, the concentration of silver heavy metal in various plant organs was increased. These results open a new pathway to consider the effect of nanoparticles on plant's productions for human consumptions.

  9. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    International Nuclear Information System (INIS)

    Moreira dos Santos, Margarida; Queiroz, Margarida João; Baptista, Pedro V.

    2012-01-01

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 ± 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a β-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle–antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  10. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moreira dos Santos, Margarida, E-mail: margarida.santos@fct.unl.pt; Queiroz, Margarida Joao; Baptista, Pedro V. [Universidade Nova de Lisboa, CIGMH, Departamento Ciencias da Vida, Faculdade de Ciencias e Tecnologia (Portugal)

    2012-05-15

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 {+-} 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a {beta}-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle-antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  11. Influence of silver addition on the microstructure and mechanical properties of squeeze cast Mg-6Al-1Sn-0.3Mn-0.3Ti

    International Nuclear Information System (INIS)

    Acikgoez, Sehzat; Sevik, Hueseyin; Kurnaz, S.Can

    2011-01-01

    Graphical abstract: Highlights: → X-ray diffractometry reveals that the main phases are α-Mg, α-Ti, β-Mg 17 Al 12 and Al 8 Mn 5 in the base alloy. → With addition of silver, Al 81 Mn 19 phase was found. → The mechanical properties of the base alloy are improved with addition of silver. → The fracture surface of base alloy shows relatively deeper and more amount of dimples than that of alloys containing silver. - Abstract: In this study, the effect of silver (0, 0.2, 0.5, and 1 wt.%) on the microstructure and mechanical properties of a magnesium-based alloy (Mg-Al 6 wt.%-Sn 1 wt.%-Mn 0.3 wt.%-Ti 0.3 wt.%) were investigated. The alloys were produced under a controlled atmosphere by a squeeze-casting process. X-ray diffractometry revealed that the main phases are α-Mg, α-Ti, β-Mg 17 Al 12 and Al 8 Mn 5 in the all of alloys. In addition to, Al 81 Mn 19 phase was found with Ag additive. Besides, the amount of β-Mg 17 Al 12 phase was decreased with increasing the amount of Ag. The strength of the base alloy was increased by solid solution mechanism and decreasing the amount of β-Mg 17 Al 12 phase with addition of Ag. Furthermore, existence of Al 81 Mn 19 phase can be acted an important role in the increase on the mechanical properties of the alloys.

  12. The enhancement of critical current density on the bulk of BPSCCO-system superconductor with silver additions

    International Nuclear Information System (INIS)

    Engkir Sukirman; Wisnu Ari Adi; Puji Sulisworo dan W Prasuad

    1999-01-01

    The influence of silver additions on the critical current density (Jc) of BPSCCO-bulk superconductor was investigated, with the aim of getting an increase of its Jc and trying to find out a correlation of Jc and structures of BPSCCO-silver composites. The BPSCCO-system superconductors with nominal composition Bi 1.84 Pb 0.34 Sr 2.00 Ca 2.03 Cu 3.06 O x (2223-phase) were synthesized by using solid state reaction method. The silver added was in the powder-AgO form varied from 0 to 30 wt % AgO. The critical current density, crystal structure, and micro-structure of BPSCCO-silver composites were characterized by means of four-point probe, x-ray diffractometer, and scanning electron microscope that is equipped with a link system energy dispersive spectrometer. It was found that silver additions to BPSCCO cause a reasonable improvement in Jc from 120 to 215 A/cm 2 , and a slight increase in Tc from 92 to 108 K, and lattice parameters of the 2223-phase from a 3.811(3) to 3.820(2) A, and from c = 37.08(3) to 37.15(2) A, with the optimum value occurs at 20 wt % AgO. The AgO powders added to the BPSCCO specimens were converted to Ag 2 O and metallic Ag during the annealing process at 827degC for 96 h in air. The addition of AgO to BPSCCO system does not necessarily lead to decomposition of the 2223-phase. The AgO reacts with and suppresses the 2201-phase. (author)

  13. Antibacterial activity of silver-killed bacteria: the "zombies" effect

    Science.gov (United States)

    Wakshlak, Racheli Ben-Knaz; Pedahzur, Rami; Avnir, David

    2015-04-01

    We report a previously unrecognized mechanism for the prolonged action of biocidal agents, which we denote as the zombies effect: biocidally-killed bacteria are capable of killing living bacteria. The concept is demonstrated by first killing Pseudomonas aeruginosa PAO1 with silver nitrate and then challenging, with the dead bacteria, a viable culture of the same bacterium: Efficient antibacterial activity of the killed bacteria is observed. A mechanism is suggested in terms of the action of the dead bacteria as a reservoir of silver, which, due to Le-Chatelier's principle, is re-targeted to the living bacteria. Langmuirian behavior, as well as deviations from it, support the proposed mechanism.

  14. Deposition and Characterization of Silver Oxide from Solution of Silver, Cassava and Sugarcane Juice Effects

    Directory of Open Access Journals (Sweden)

    Uche E. Ekpunobi

    2013-06-01

    Full Text Available Silver oxide was deposited on metallic substrates (zinc and lead from silver solution with different additives at a pH of 5, dc current of 0.2A, 4V for 20seconds at 25°C. The additives were cassava solution and sugarcane juice. The metallic substrates served as cathode while a copper electrode serves as the anode. Compositions of the electrolytes were 50ml AgNO3, 50ml AgNO3 and 50ml of cassava solution or 50ml of sugarcane juice. Structural and textural characterizations were carried out on the deposits. The result showed that deposition using zinc substrate gave a better result than that of lead in that the deposits were pure without impurities. Using cassava solution as additive, a pure Ag2O3 deposit was obtained while sugarcane juice gave a pure intergrowth of Ag2O3 and Ag3O4 deposits both on zinc substrates.

  15. Polyvinylpyrrolidone Matrix as an Effective Reducing Agent and Stabilizer during Reception of Silver Nanoparticles in Composites

    OpenAIRE

    Semenyuk, Nataliya; Kostiv, Ulyana; Dudok, Galyna; Nechay, Jaroslav; Skorokhoda, Volodymyr

    2013-01-01

    The use of polyvinylpyrrolidone matrix as an effective reducing agent and stabilizer during reception of silver nanoparticles in composites is substantiated. The influence of various factors on patterns of obtaining silver nanoparticles and their size.

  16. Silver nanoparticle catalysed redox reaction: An electron relay effect

    International Nuclear Information System (INIS)

    Mallick, Kaushik; Witcomb, Mike; Scurrell, Mike

    2006-01-01

    A silver cluster shows efficient catalytic activity in a redox reaction because the cluster acts as the electron relay centre behaving alternatively as an acceptor and as a donor of electrons. An effective transfer of electrons is possible when the redox potential of the cluster is intermediate between the electron donor and electron acceptor system

  17. Effect of methyl jasmonate and silver nanoparticles on production of ...

    African Journals Online (AJOL)

    Conclusion: Treatment of C. officinalis L. with SNPs and MeJA seems to be a simple and cost-effective method of improving the medicinal properties of this plant. Keywords: Calendula officinalis, Silver nanoparticles, Methyl jasmonate, Secondary metabolites, HeLa cells, Membrane lipid peroxidation, Radical scavenging ...

  18. The effects of silver coating on friction coefficient and shear bond strength of steel orthodontic brackets.

    Science.gov (United States)

    Arash, Valiollah; Anoush, Keivan; Rabiee, Sayed Mahmood; Rahmatei, Manuchehr; Tavanafar, Saeid

    2015-01-01

    Aims of the present study was to measure frictional resistance between silver coated brackets and different types of arch wires, and shear bond strength of these brackets to the tooth. In an experimental clinical research 28 orthodontic brackets (standard, 22 slots) were coated with silver ions using electroplate method. Six brackets (coated: 3, uncoated: 3) were evaluated with Scanning Electron Microscopy and Atomic Force Microscopy. The amount of friction in 15 coated brackets was measured with three different kinds of arch wires (0.019 × 0.025-in stainless steel [SS], 0.018-in stainless steel [SS], 0.018-in Nickel-Titanium [Ni-Ti]) and compared with 15 uncoated steel brackets. In addition, shear bond strength values were compared between 10 brackets with silver coating and 10 regular brackets. Universal testing machine was used to measure shear bond strength and the amount of friction between the wires and brackets. SPSS 18 was used for data analysis with t-test. SEM and AFM results showed deposition of a uniform layer of silver, measuring 8-10 μm in thickness on bracket surfaces. Silver coating led to higher frictional forces in all the three types of arch wires, which was statistically significant in 0.019 × 0.025-in SS and 0.018-in Ni-Ti, but it did not change the shear bond strength significantly. Silver coating with electroplating method did not affect the bond strength of the bracket to enamel; in addition, it was not an effective method for decreasing friction in sliding mechanics. © Wiley Periodicals, Inc.

  19. Antibacterial effect of silver nanofilm modified stainless steel surface

    Science.gov (United States)

    Fang, F.; Kennedy, J.; Dhillon, M.; Flint, S.

    2015-03-01

    Bacteria can attach to stainless steel surfaces, resulting in the colonization of the surface known as biofilms. The release of bacteria from biofilms can cause contamination of food such as dairy products in manufacturing plants. This study aimed to modify stainless steel surfaces with silver nanofilms and to examine the antibacterial effectiveness of the modified surface. Ion implantation was applied to produce silver nanofilms on stainless steel surfaces. 35 keV Ag ions were implanted with various fluences of 1 × 1015 to 1 × 1017 ions•cm-2 at room temperature. Representative atomic force microscopy characterizations of the modified stainless steel are presented. Rutherford backscattering spectrometry spectra revealed the implanted atoms were located in the near-surface region. Both unmodified and modified stainless steel coupons were then exposed to two types of bacteria, Pseudomonas fluorescens and Streptococcus thermophilus, to determine the effect of the surface modification on bacterial attachment and biofilm development. The silver modified coupon surface fluoresced red over most of the surface area implying that most bacteria on coupon surface were dead. This study indicates that the silver nanofilm fabricated by the ion implantation method is a promising way of reducing the attachment of bacteria and delay biofilm formation.

  20. 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.

  1. Synthesis of Quinuclidines by Intramolecular Silver-​Catalysed Amine Additions to Alkynes

    NARCIS (Netherlands)

    Breman, A.C.; Ruiz-Olalla, A.; van Maarseveen, J.H.; Ingemann, S.; Hiemstra, H.

    2014-01-01

    A new method has been developed for the synthesis of 2-​alkylidenequinuclidines based on a silver triflate catalyzed intramol. hydroamination of 4-​(prop-​2-​ynyl)​piperidines. Monosubstituted piperidines reacted less efficiently than cis-​disubstituted piperidines, and the reaction was selective

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

    Science.gov (United States)

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

    2013-01-01

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

  3. Time-dependent effect in green synthesis of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Darroudi M

    2011-04-01

    Full Text Available Majid Darroudi1,2, Mansor Bin Ahmad3, Reza Zamiri4, AK Zak5, Abdul Halim Abdullah1,3, Nor Azowa Ibrahim31Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA, Universiti Putra Malaysia, Selangor, Malaysia; 2Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran; 3Department of Chemistry, 4Department of Physics, Faculty of Science, Universiti Putra Malaysia, Selangor, Malaysia; 5Low Dimensional Materials Research Center, Department of Physics, Faculty of Science, University of Malaya, Kuala Lumpur, MalaysiaAbstract: The application of “green” chemistry rules to nanoscience and nanotechnology is very important in the preparation of various nanomaterials. In this work, we successfully developed an eco-friendly chemistry method for preparing silver nanoparticles (Ag-NPs in natural polymeric media. The colloidal Ag-NPs were synthesized in an aqueous solution using silver nitrate, gelatin, and glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag-NPs were studied at different reaction times. The ultraviolet-visible (UV-vis spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM and their size distributions. The prepared samples were also characterized by X-ray diffraction (XRD and atomic force microscopy (AFM. The use of eco-friendly reagents, such as gelatin and glucose, provides green and economic attributes to this work.Keywords: silver nanoparticles, gelatin, green chemistry, time-dependent effect, ultraviolet-visible spectra

  4. Deposition of silver nanoparticles on titanium surface for antibacterial effect

    Directory of Open Access Journals (Sweden)

    Liao Juan

    2010-04-01

    Full Text Available Liao Juan1, Zhu Zhimin3, Mo Anchun1,2, Li Lei1, Zhang Jingchao11State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, PR China; 2Department of Dental Implant, West China Stomatology Hospital, Sichuan University, Chengdu 610041, PR China; 3Department of Prosthodontics, West China Stomatology Hospital, Sichuan University, Chengdu 610041, PR ChinaAbstract: Microbial colonization on implanted devices and biofilm formation is a recurrent complication in implant surgery and may result in loss of implants. The aim of this study was to deposit silver nanoparticles on a titanium surface to obtain antibacterial properties. In the present study, we prepared a silver nanoparticle-modified titanium (Ti-nAg surface using silanization method. The morphology and chemical components of the Ti-nAg surface were characterized by scanning electron microscopy (SEM equipped with energy-dispersive spectroscopy (EDS. Two species of bacteria, Staphylococcus aureus and Escherichia coli, were utilized to test the antibacterial effect of the Ti-nAg treated surface. The SEM examination revealed that a small quantity of silver nanoparticles was sparsely deposited on the titanium surface. The diameter of these nanoparticles ranged from ten to several hundred nm. EDS analyses revealed that there was 4.26% of Ag present on the surface. After a 24-hour incubation, 94% of Staphylococcus aureus and over 95% of Escherichia coli had been killed on the Ti-nAg surface, and the SEM examination of anti-adhesive efficacy test showed that there were less bacteria attached to Ti-nAg surface than to a control surface of untreated Titanium. These data suggest that silver nanoparticle-modified titanium is a promising material with an antibacterial property that may be used as an implantable biomaterial.Keywords: nano-silver, titanium, antibacterial activity, silanization method

  5. Effect of Chemical Stabilizers in Silver Nanoparticle Suspensions on Nanotoxicity

    International Nuclear Information System (INIS)

    Bae, Eun Joo; Park, Hee Jin; Park, Jun Su; Yoon, Je Yong; Yi, Jong Heop; Kim, Young Hun; Choi, Kyung Hee

    2011-01-01

    Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers

  6. Effect of Chemical Stabilizers in Silver Nanoparticle Suspensions on Nanotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Eun Joo; Park, Hee Jin; Park, Jun Su; Yoon, Je Yong; Yi, Jong Heop [Seoul National University, Seoul (Korea, Republic of); Kim, Young Hun [Kwangwoon University, Seoul (Korea, Republic of); Choi, Kyung Hee [National Institute of Environmental Research, Incheon (Korea, Republic of)

    2011-02-15

    Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers.

  7. effects of sulphur addition on addition on and mechanical properties

    African Journals Online (AJOL)

    User

    234-8034714355. 8034714355. 1. EFFECTS OF SULPHUR ADDITION ON. ADDITION ON. 2. AND MECHANICAL PROPERTIES O. 3. 4. C. W. Onyia. 5. 1DEPT. OF METALLURGICAL AND MATERIALS. 6. 2, 4DEPT. OF METALLURGICAL ...

  8. Mixed moderate thermophilic bioleaching of Cu, Mo and Re from molybdenite concentrate: effects of silver ion, medium and energy sources

    Directory of Open Access Journals (Sweden)

    Hadi Abdollahi

    2017-12-01

    Full Text Available This study evaluates the effects of different additives such as silver ion, medium and energy sources on the efficiency of mixed moderate thermophilic bioleaching approach to extract Cu, Mo and Re from molybdenite concentrate containing 0.98% Cu, 1.56% Fe, 53.84% Mo, and 0.055% Re. Molybdenite was the major phase of Mo-bearing mineral and chalcopyrite, covellite and pyrite were distinguished as minor phases. The higher copper extraction was obtained in tests with silver additives in all types and quantities rather than tests without silver ion. Kinetic of copper dissolution varied in these experiments and depended on the types and amounts of silver, and other supplemented additives such as ferric ion. There was no clear difference in the copper extraction by various culture media and 100% of Cu was dissolved after 30 days of treatment, using 50 mg/L of silver nitrate as additives. In the best condition and without silver additives, maximum 60% of copper was extracted even in the presence of energy sources such as sulfur, ferrous and ferric ions. In the most effective test with initial pH 1.57, 50 mg/L silver nitrate, and 50 g/L ferric sulfate, 100% of copper was dissolved in less than a week with highest kinetics rate. Molybdenum and rhenium extraction had the same tends with redox potential graph. By increasing the redox potential to the 550-600mV, molybdenite started to dissolve and finally, molybdenum and rhenium were extracted 2% and 9.53% in the best condition; respectively.

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

    Science.gov (United States)

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

    2017-06-01

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

  10. Modeling molecular effects on plasmon transport: Silver nanoparticles with tartrazine

    Science.gov (United States)

    Arntsen, Christopher; Lopata, Kenneth; Wall, Michael R.; Bartell, Lizette; Neuhauser, Daniel

    2011-02-01

    Modulation of plasmon transport between silver nanoparticles by a yellow fluorophore, tartrazine, is studied theoretically. The system is studied by combining a finite-difference time-domain Maxwell treatment of the electric field and the plasmons with a time-dependent parameterized method number 3 simulation of the tartrazine, resulting in an effective Maxwell/Schrödinger (i.e., classical/quantum) method. The modeled system has three linearly arranged small silver nanoparticles with a radius of 2 nm and a center-to-center separation of 4 nm; the molecule is centered between the second and third nanoparticles. We initiate an x-polarized current on the first nanoparticle and monitor the transmission through the system. The molecule rotates much of the x-polarized current into the y-direction and greatly reduces the overall transmission of x-polarized current.

  11. [Effects of silver nitrate on the phase state of model multibilayer membranes].

    Science.gov (United States)

    Vashchenko, O V; Iermak, Yu L; Krasnikova, A O; Lisetski, L N

    2015-01-01

    In order to study the effects caused by silver nitrate (AgNO3) on model lipid membranes, we studied multibilayer membranes based on L-α-dipalmitoylphosphatidylcholine (DPPC) and AgNO3 aqueous soluitions in a wide concentration range (up to 30 wt%) by means of differential scanning calorimetry. It has been shown that the presence of AgNO3 leads both to an increase in the main phase transition temperature (T(m)) and appearance of an additional phase transition peak (T(m)), suggesting increasing of both density and heterogeneity of the lipid membrane. The effect of nitrate ions (NO ) was shown to be of the opposite nature (bilayer fluidizing), so the integral densifying effect of AgNO3 can be referred solely to the action of silver ions (Ag(+)). With increasing AgNO3 concentration, the tendency was observed to opposite changes in T(m) and T'(m) peaks intensity, thereby at about 26. wt% of AgNO3 the initial peak (T(m)) disappeared. In the range of Ag+ therapeutic concentrations (up to 2 wt%) no significant changes in the DPPC membrane were revealed. This can be one of the reasons of the absence of a damaging effect of silver drugs on a host organism with simultaneous pronounced bactericidal effect.

  12. Influence of silver additions to type 316 stainless steels on bacterial inhibition, mechanical properties, and corrosion resistance

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Tseng, I-Sheng; Møller, Per

    2010-01-01

    Bacterial contamination is a major concern in many areas. In this study, silver was added to type 316 stainless steels in order to obtain an expected bacteria inhibiting property to reduce the occurrence of bacterial contamination. Silver-bearing 316 stainless steels were prepared by vacuum melting...... in areas where hygiene is a major requirement. The possible mechanisms of silver dissolution from the surfaces of silver-bearing 316 stainless steels were also discussed in this report....

  13. Assessing antibacterial effect of filter media coated with silver nanoparticles against Bacillus spp

    Directory of Open Access Journals (Sweden)

    Mahmood Nafisi Bahabadi

    2016-04-01

    Full Text Available Background: Nanotechnology is a field of applied science and technology covering a broad range of topics. Use of nanotechnology and especially silver nanoparticles in control of bacterial diseases and infections has been studied in the recent years. The aim of the present study was to investigate the in vitro antibacterial effect of filter media coated with silver nanoparticles against Bacillus spp. Materials and methods: In this research, first, the antibacterial effects of silver nanoparticles against mentioned bacteria were evaluated by microdilution method in Broth medium. After confidence of inhibitory effect of colloidal silver nanoparticles, antibacterial effect of filter media coated with silver nanoparticles was evaluated via in vitro microbiology tests (zone of inhibition test and test tube test. Results: Present study showed that colloidal silver nanoparticles have good antimicrobial effects against tested bacteria, so that MIC and MBC of silver nanoparticles for Bacillus spp. were calculated 3.9 and 31.25 mg/L, respectively. Also significant decrease was observed in bacterial growth after exposure to filter media coated with silver nanoparticles in test tube test and  zone of inhibition test (P≤ 5%. Conclusion: The results of this research indicate that filter media coated with silver nanoparticles have considerable antimicrobial effects; therefore they could possibly be used as excellent antibacterial water filters and would have several applications in other sectors.

  14. 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.

  15. The Effects of in Situ-Formed Silver Nanoparticles on the Electrical Properties of Epoxy Resin Filled with Silver Nanowires

    Directory of Open Access Journals (Sweden)

    Gwang-Seok Song

    2016-04-01

    Full Text Available A novel method for preparing epoxy/silver nanocomposites was developed via the in situ formation of silver nanoparticles (AgNPs within the epoxy resin matrix while using silver nanowires (AgNWs as a conductive filler. The silver–imidazole complex was synthesized from silver acetate (AgAc and 1-(2-cyanoethyl-2-ethyl-4-methylimidazole (imidazole. AgNPs were generated in situ during the curing of the epoxy resin through the thermal decomposition of the AgAc–imidazole complex, which was capable of reducing Ag+ to Ag by itself. The released imidazole acted as a catalyst to cure the epoxy. Additionally, after the curing process, the in situ-generated AgNPs were stabilized by the formed epoxy network. Therefore, by using the thermal decomposition method, uniformly dispersed AgNPs of approximately 100 nm were formed in situ in the epoxy matrix filled with AgNWs. It was observed that the nanocomposites containing in situ-formed AgNPs exhibited isotropic electrical properties in the epoxy resins in the presence of AgNWs.

  16. The effects of silver ions on copper metabolism in rats.

    Science.gov (United States)

    Ilyechova, E Yu; Saveliev, A N; Skvortsov, A N; Babich, P S; Zatulovskaia, Yu A; Pliss, M G; Korzhevskii, D E; Tsymbalenko, N V; Puchkova, L V

    2014-10-01

    The influence of short and prolonged diet containing silver ions (Ag-diet) on copper metabolism was studied. Two groups of animals were used: one group of adult rats received a Ag-diet for one month (Ag-A1) and another group received a Ag-diet for 6 months from birth (Ag-N6). In Ag-A1 rats, the Ag-diet caused a dramatic decrease of copper status indexes that was manifested as ceruloplasmin-associated copper deficiency. In Ag-N6 rats, copper status indexes decreased only 2-fold as compared to control rats. In rats of both groups, silver entered the bloodstream and accumulated in the liver. Silver was incorporated into ceruloplasmin (Cp), but not SOD1. In the liver, a prolonged Ag-diet caused a decrease of the expression level of genes, associated with copper metabolism. Comparative spectrophotometric analysis of partially purified Cp fractions has shown that Cp from Ag-N6 rats was closer to holo-Cp by specific enzymatic activities and tertiary structure than Cp from Ag-A1 rats. However, Cp of Ag-N6 differs from control holo-Cp and Cp of Ag-A1 in its affinity to DEAE-Sepharose and in its binding properties to lectins. In the bloodstream of Ag-N6, two Cp forms are present as shown in pulse-experiments on rats with the liver isolated from circulation. One of the Cp isoforms is of hepatic origin, and the other is of extrahepatic origin; the latter is characterized by a faster rate of secretion than hepatic Cp. These data allowed us to suggest that the disturbance of holo-Cp formation in the liver was compensated by induction of extrahepatic Cp synthesis. The possible biological importance of these effects is discussed.

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

    International Nuclear Information System (INIS)

    Tsai, Jung-Ting; Lin, Shun-Tian

    2013-01-01

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

  18. Silver nanoparticles plasmonic effect on eosin and rhodamine 6G luminescence in various media

    Science.gov (United States)

    Samusev, Ilia G.; Tikhomirova, Nadezhda S.; Slezhkin, Vasiliy A.; Zyubin, Andrey Yu.; Bryukhanov, Valery V.; Tsibulnikova, Anna V.

    2016-11-01

    The plasmonic enhancement and quenching of phosphorescence and fluorescence of the anionic (eosin) and cationic (rhodamine 6G) dyes have been studied in various environments: silver nanoparticles of silver hydrosol citrate in water, in polymer films and on the surface of nanoporous silica in order to determine the kinetic and spectral effects on the dye luminescence. Depending on the silver nanoparticles concentration both the enhancement and quenching of the dyes phosphorescence and fluorescence have been detected. The mechanism of interaction between the excited molecules and silver nanoparticles has been discussed.

  19. Cytotoxic and genotoxic effects of silver nanoparticles in testicular cells

    International Nuclear Information System (INIS)

    Asare, Nana; Instanes, Christine; Sandberg, Wiggo J.; Refsnes, Magne; Schwarze, Per; Kruszewski, Marcin; Brunborg, Gunnar

    2012-01-01

    Serious concerns have been expressed about potential risks of engineered nanoparticles. Regulatory health risk assessment of such particles has become mandatory for the safe use of nanomaterials in consumer products and medicines; including the potential effects on reproduction and fertility, are relevant for this risk evaluation. In this study, we examined effects of silver particles of nano- (20 nm) and submicron- (200 nm) size, and titanium dioxide nanoparticles (TiO 2 -NPs; 21 nm), with emphasis on reproductive cellular- and genotoxicity. Ntera2 (NT2, human testicular embryonic carcinoma cell line), and primary testicular cells from C57BL6 mice of wild type (WT) and 8-oxoguanine DNA glycosylase knock-out (KO, mOgg1 −/− ) genotype were exposed to the particles. The latter mimics the repair status of human testicular cells vs oxidative damage and is thus a suitable model for human male reproductive toxicity studies. The results suggest that silver nano- and submicron-particles (AgNPs) are more cytotoxic and cytostatic compared to TiO 2 -NPs, causing apoptosis, necrosis and decreased proliferation in a concentration- and time-dependent manner. The 200 nm AgNPs in particular appeared to cause a concentration-dependent increase in DNA-strand breaks in NT2 cells, whereas the latter response did not seem to occur with respect to oxidative purine base damage analysed with any of the particles tested.

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

    Directory of Open Access Journals (Sweden)

    S. Kazemipour

    2016-02-01

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

  1. Effect of valence on the electromigration in silver

    International Nuclear Information System (INIS)

    Nguyen Van Doan

    1970-01-01

    It is shown that the apparent effective valence Z B ** of a solute deduced from experiments differs from the true effective valence Z B * defined in the atomic models by a corrective term due to the 'vacancy flow effect'. The experimental results suggest that this corrective term is very important and that it is negative for transition elements; this hypothesis is confirmed for the case of iron in a copper matrix. For the elements to the right of silver in the periodic table, where the correction can be neglected, the effective valence of the solute varies linearly with z (z + 1), z being the difference between the valency of the solute and the solvent; in contrast, the further the solute is from the solvent in the periodic table the more nearly the electronic structure of the ion at the saddle point resembles that of the ion at the equilibrium position. (author) [fr

  2. Effects of Prolonged Silver Nanoparticle Exposure on the Contextual Cognition and Behavior of Mammals

    Directory of Open Access Journals (Sweden)

    Anna Antsiferova

    2018-04-01

    Full Text Available Silver nanoparticles have been widely used in the lighting and food industries, in medicine, and in pharmaceutics as an antiseptic agent. Recent research demonstrates that, after prolonged oral administration, silver nanoparticles may cross the blood-brain barrier and accumulate in the brain in rather high amounts. In ex vivo experiments, it has also been shown that silver nanoparticles demonstrate neurotoxicity. The objective of this work was to answer the questions whether silver nanoparticles change cognitive and behavioral functions of mammals after prolonged administration if silver nanoparticles have accumulated in the brain. C57Bl/6 male mice were orally exposed to PVP-coated silver nanoparticles daily for 30, 60, 120 and 180 days. Control mice were exposed to distilled water. After that they were tested in the Open Field, Elevated Plus Maze, Light-Dark Box and contextual fear conditioning task. The data have shown that the experimental mice went through three periods of switching in the behavior caused by adaptation to the toxic silver nanoparticles: anxiety, appearance of research instinct and impairment of long-term memory. This provides evidence of the hazardous effect of silver nanoparticles, which appears after long periods of silver nanoparticle oral administration.

  3. The effect of biologically and chemically synthesized silver nanoparticles (AgNPs) on biofilm formation

    Science.gov (United States)

    Chojniak, Joanna; Biedroń, Izabela; Mendrek, Barbara; Płaza, Grażyna

    2017-11-01

    Bionanotechnology has emerged up as integration between biotechnology and nanotechnology for developing biosynthetic and environmental-friendly technology for synthesis of nanomaterials. Different types of nanomaterials like copper, zinc, titanium, magnesium, gold, and silver have applied in the various industries but silver nanoparticles have proved to be most effective against bacteria, viruses and eukaryotic microorganisms. The antimicrobial property of silver nanoparticles are widely known. Due to strong antibacterial property silver nanoparticles are used, e.g. in clothing, food industry, sunscreens, cosmetics and many household and environmental appliances. The aim of the study was to compare the effect of silver nanoparticles (AgNPs) synthesized biologically and chemically on the biofilm formation. The biofilm was formed by the bacteria isolated from the water supply network. The commonly used crystal violet assay (CV) was applied for biofilm analysis. In this study effect of biologically synthesized Ag-NPs on the biofilm formation was evaluated.

  4. A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

    Science.gov (United States)

    Marambio-Jones, Catalina; Hoek, Eric M. V.

    2010-06-01

    Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules—all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

  5. A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

    Energy Technology Data Exchange (ETDEWEB)

    Marambio-Jones, Catalina; Hoek, Eric M. V., E-mail: emvhoek@ucla.ed [University of California, Los Angeles, Department of Civil and Environmental Engineering, California NanoSystems Institute (United States)

    2010-06-15

    Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules-all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

  6. A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

    International Nuclear Information System (INIS)

    Marambio-Jones, Catalina; Hoek, Eric M. V.

    2010-01-01

    Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules-all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

  7. Antibacterial Behavior of Additively Manufactured Porous Titanium with Nanotubular Surfaces Releasing Silver Ions

    NARCIS (Netherlands)

    Amin Yavari, S.; Loozen, L.; Paganelli, F. L.; Bakhshandeh, S.; Lietaert, K.; Groot, J. A.; Fluit, A. C.; Boel, C. H E; Alblas, J.; Vogely, H. C.; Weinans, H.; Zadpoor, A. A.

    2016-01-01

    Additive manufacturing (3D printing) has enabled fabrication of geometrically complex and fully interconnected porous biomaterials with huge surface areas that could be used for biofunctionalization to achieve multifunctional biomaterials. Covering the huge surface area of such porous titanium with

  8. Quantitative Proteomics Reveals Ecophysiological Effects of Light and Silver Stress on the Mixotrophic Protist Poterioochromonas malhamensis.

    Directory of Open Access Journals (Sweden)

    Daniela Beisser

    Full Text Available Aquatic environments are heavily impacted by human activities including climate warming and the introduction of xenobiotics. Due to the application of silver nanoparticles as bactericidal agent the introduction of silver into the environment strongly has increased during the past years. Silver ions affect the primary metabolism of algae, in particular photosynthesis. Mixotrophic algae are an interesting test case as they do not exclusively rely on photosynthesis which may attenuate the harmful effect of silver. In order to study the effect of silver ions on mixotrophs, cultures of the chrysophyte Poterioochromonas malhamensis were treated in a replicate design in light and darkness with silver nitrate at a sub-lethal concentration. At five time points samples were taken for the identification and quantitation of proteins by mass spectrometry. In our analysis, relative quantitative protein mass spectrometry has shown to be a useful tool for functional analyses in conjunction with transcriptome reference sequences. A total of 3,952 proteins in 63 samples were identified and quantified, mapping to 4,829 transcripts of the sequenced and assembled transcriptome. Among them, 720 and 104 proteins performing various cellular functions were differentially expressed after eight days in light versus darkness and after three days of silver treatment, respectively. Specifically pathways of the energy and primary carbon metabolism were differentially affected by light and the utilization of expensive reactions hints to an energy surplus of P. malhamensis under light conditions. The excess energy is not invested in growth, but in the synthesis of storage metabolites. The effects of silver were less explicit, observable especially in the dark treatments where the light effect could not mask coinciding but weaker effects of silver. Photosynthesis, particularly the light harvesting complexes, and several sulphur containing enzymes were affected presumably due to

  9. Synthesis of silver doped hydroxyapatite nanospheres using Ouzo effect

    Directory of Open Access Journals (Sweden)

    Marija Prekajski

    2016-09-01

    Full Text Available Nanoemulsion technique, based on Ouzo effect, was applied for synthesis of the pure and silver doped (2.5 and 5 mol% calcium hydroxyapatite (HAp. After calcination at 500 °C fully crystallized powders were obtained. X-ray powder diffraction analysis accompanied with Rietveld refinement revealed that the synthesized powders were single-phase hydroxyapatite. Raman spectroscopy also confirmed that the synthesized powders were single-phase. The obtained HAp particles were spherical in shape and their sizes were in the nanometer range which was revealed by field emission scanning electron microscopy analysis (FESEM. The successful synthesis of the single-phase Ag doped HAp showed that nanoemulsion method is a simple technique for obtaining pure and doped hydroxyapatite nanospheres.

  10. Point-of-Use Removal of Cryptosporidium parvum from Water: Independent Effects of Disinfection by Silver Nanoparticles and Silver Ions and by Physical Filtration in Ceramic Porous Media.

    Science.gov (United States)

    Abebe, Lydia S; Su, Yi-Hsuan; Guerrant, Richard L; Swami, Nathan S; Smith, James A

    2015-11-03

    Ceramic water filters (CWFs) impregnated with silver nanoparticles are a means of household-level water treatment. CWFs remove/deactivate microbial pathogens by employing two mechanisms: metallic disinfection and physical filtration. Herein we report on the independent effects of silver salt and nanoparticles on Cryptosporidium parvum and the removal of C. parvum by physical filtration in porous ceramic filter media. Using a murine (mouse) model, we observed that treatment of oocysts with silver nitrate and proteinate-capped silver nanoparticles resulted in decreased infection relative to untreated oocysts. Microscopy and excystation experiments were conducted to support the disinfection investigation. Heat and proteinate-capped silver-nanoparticle treatment of oocysts resulted in morphological modifications and decreased excystation rates of sporozoites. Subsequently, disk-shaped ceramic filters were produced to investigate the transport of C. parvum. Two factors were varied: sawdust size and clay-to-sawdust ratio. Five disks were prepared with combinations of 10, 16, and 20 mesh sawdust and sawdust percentage that ranged from 9 to 11%. C. parvum removal efficiencies ranged from 1.5 log (96.4%) to 2.1 log (99.2%). The 16-mesh/10% sawdust had the greatest mean reduction of 2.1-log (99.2%), though there was no statistically significant difference in removal efficiency. Based on our findings, physical filtration and silver nanoparticle disinfection likely contribute to treatment of C. parvum for silver impregnated ceramic water filters, although the contribution of physical filtration is likely greater than silver disinfection.

  11. The Effect of Ultrasonic Additive Manufacturing on Integrated Printed Electronic Conductors

    Science.gov (United States)

    Bournias-Varotsis, Alkaios; Wang, Shanda; Hutt, David; Engstrøm, Daniel S.

    2018-03-01

    Ultrasonic additive manufacturing (UAM) is a low temperature manufacturing method capable of embedding printed electronics in metal components. The effect of UAM processing on the resistivity of conductive tracks printed with five different conductive pastes based on silver, copper or carbon flakes/particles in either a thermoplastic or thermoset filler binder are investigated. For all but the carbon-based paste, the resistivity changed linearly with the UAM energy input. After UAM processing, a resistivity increase of more than 150 times was recorded for the copper based thermoset paste. The silver based pastes showed a resistivity increase of between 1.1 and 50 times from their initial values. The carbon-based paste showed no change in resistivity after UAM processing. Focussed ion beam microstructure analysis of the printed conductive tracks before and after UAM processing showed that the silver particles and flakes in at least one of the pastes partly dislodged from their thermoset filler creating voids, thereby increasing the resistivity, whereas the silver flakes in a thermoplastic filler did not dislodge due to material flow of the polymer binder. The lowest resistivity (8 × 10-5 Ω cm) after UAM processing was achieved for a thermoplastic paste with silver flakes at low UAM processing energy.

  12. The Effect of Ultrasonic Additive Manufacturing on Integrated Printed Electronic Conductors

    Science.gov (United States)

    Bournias-Varotsis, Alkaios; Wang, Shanda; Hutt, David; Engstrøm, Daniel S.

    2018-07-01

    Ultrasonic additive manufacturing (UAM) is a low temperature manufacturing method capable of embedding printed electronics in metal components. The effect of UAM processing on the resistivity of conductive tracks printed with five different conductive pastes based on silver, copper or carbon flakes/particles in either a thermoplastic or thermoset filler binder are investigated. For all but the carbon-based paste, the resistivity changed linearly with the UAM energy input. After UAM processing, a resistivity increase of more than 150 times was recorded for the copper based thermoset paste. The silver based pastes showed a resistivity increase of between 1.1 and 50 times from their initial values. The carbon-based paste showed no change in resistivity after UAM processing. Focussed ion beam microstructure analysis of the printed conductive tracks before and after UAM processing showed that the silver particles and flakes in at least one of the pastes partly dislodged from their thermoset filler creating voids, thereby increasing the resistivity, whereas the silver flakes in a thermoplastic filler did not dislodge due to material flow of the polymer binder. The lowest resistivity (8 × 10-5 Ω cm) after UAM processing was achieved for a thermoplastic paste with silver flakes at low UAM processing energy.

  13. Antimicrobial effects of zinc oxide nanoparticles modified with silver

    International Nuclear Information System (INIS)

    Lopes, Rayssa Souza; Arantes, Tatiane Moraes

    2016-01-01

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

  14. Antimicrobial effects of zinc oxide nanoparticles modified with silver

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-01

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

  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. Effects of electrolytes and surfactants on the morphology and stability of advanced silver nano-materials

    Energy Technology Data Exchange (ETDEWEB)

    Obaid, Abdullah Yousif; AL-Thabaiti, Shaeel Ahmed; El-Mossalamy, E.H. [Department of Chemistry, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21413 (Saudi Arabia); Hussain, Javed Ijaz [Nano-science Research Lab, Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi 110 025 (India); Khan, Zaheer, E-mail: drkhanchem@yahoo.co.in [Nano-science Research Lab, Department of Chemistry, Jamia Millia Islamia (Central University), New Delhi 110 025 (India)

    2013-03-15

    Highlights: ► Stoichiometric ratio of S{sub 2}O{sub 3}{sup 2−} and Ag{sup +} ions are responsible to the formation of prefect transparent yellow colored silver sol. ► Higher S{sub 2}O{sub 3}{sup 2−} concentrations has damping effect. ► Head group of the surfactants and nature of the electrolytes have significant effect on the stability of silver nanoparticles. - Abstract: The impact of electrolytes, stabilizing and/or capping agents on morphology of colloidal silver nano-materials (AgNPs) has been studied spectroscopically. Sodium thiosulfate acts as reducing-, stabilizing- and damping-agents. Stoichiometric ratios of S{sub 2}O{sub 3}{sup 2−} and Ag{sup +} ions were responsible to the formation stable and prefect transparent dark yellow colored AgNPs. The S{sub 2}O{sub 3}{sup 2−}-stabilized AgNPs were significantly more stable in inorganic electrolytes (NaNO{sub 3}, Na{sub 2}SO{sub 4}, Na{sub 2}CO{sub 3} and KBr). S{sub 2}O{sub 3}{sup 2−} is adsorbed more strongly than the used other anions. The addition of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) has significant effects on the absorbance of S{sub 2}O{sub 3}{sup 2−}-stabilized AgNPs which can be rationalized in terms of electrostatic attraction and repulsion between the adsorbed S{sub 2}O{sub 3}{sup 2−} ions on to the surface of AgNPs and cationic and/or anionic head groups of used surfactants, respectively. Transmission electron microscopy images suggest that AgNPs are polydispersed, spherical and exhibiting an interesting irregular morphology.

  17. Silver Nanocube and Nanobar Growth via Anisotropic Monomer Addition and Particle Attachment Processes.

    Science.gov (United States)

    Xiao, Dongdong; Wu, Zhigang; Song, Miao; Chun, Jaehun; Schenter, Gregory K; Li, Dongsheng

    2018-01-30

    Understanding the growth mechanism of noble metal nanocrystals during solution synthesis is of significant importance for shape and property control. However, much remains unknown about the growth pathways of metal nanoparticles due to the lack of direct observation. Using an in situ transmission electron microscopy technique, we directly observed Ag nanocube and nanobar growth in an aqueous solution through both classical monomer-by-monomer addition and nonclassical particle attachment processes. During the particle attachment process, Ag nanocubes and nanobars were formed via both oriented and nonoriented attachment. Our calculations, along with the dynamics of the observed attachment, showed that the van der Waals force overcomes hydrodynamic and friction forces and drives the particles toward each other at separations of 10-100 nm in our experiments. During classical growth, anisotropic growth was also revealed, and the resulting unsymmetrical shape constituted an intermediate state for Ag nanocube growth. We hypothesized that the temporary symmetry breaking resulted from different growth rates on (001) surfaces due to a local surface concentration variation caused by the imbalance between the consumption of Ag + near the surface and the diffusion of Ag + from the bulk to the surface.

  18. Silver Nanocube and Nanobar Growth via Anisotropic Monomer Addition and Particle Attachment Processes

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Dongdong [Physical; Wu, Zhigang [School; Song, Miao [Physical; Chun, Jaehun [Physical; Schenter, Gregory K. [Physical; Li, Dongsheng [Physical

    2018-01-11

    Understanding the growth mechanism of noble metal nanocrystals during solution synthesis is of significant importance for shape and property control. However, much remains unknown about the growth pathways of metal nanoparticles due to lack of direct observation. Using an in-situ transmission electron microscopy technique, we directly observed Ag nanocube and nanobar growth in aqueous solution through both classical monomer-by-monomer addition and non-classical particle attachment processes. During the particle attachment process, Ag nanocubes and nanobars formed via both oriented and non-oriented attachment. Our calculations, along with dynamics of the observed attachment, showed that van der Waals force overcame hydrodynamic and friction forces and drove the particles toward each other. During classical growth, an anisotropic growth was also revealed, and the resulting unsymmetrical shape constituted an intermediate state for Ag nanocube growth. We hypothesized that the temporary symmetry breaking resulted from different growth rates on {001} surfaces due to a local surface concentration variation caused by the imbalance between the consumption of Ag+ near the surface and the diffusion of Ag+ from bulk to surface.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  20. Silver doped titanium dioxide nanoparticles as antimicrobial additives to dental polymers.

    Science.gov (United States)

    Chambers, C; Stewart, S B; Su, B; Jenkinson, H F; Sandy, J R; Ireland, A J

    2017-03-01

    The objectives of this in vitro study were to produce a filled resin containing Ag-TiO 2 filler particles and to test its antibacterial properties. Ag-TiO 2 particles were manufactured using the ball milling method and incorporated into an epoxy resin using a high speed centrifugal mixer. Using UV/vis spectrophotometry investigations were performed to assess how the photocatalytic properties of the Ag-TiO 2 particles are affected when encased in resin. Adopting the bacteria colony counting technique, the antibacterial properties of Ag-TiO 2 particles and Ag-TiO 2 containing resins were assessed using Streptococcus mutans under varying lighting conditions. Ag doping of TiO 2 results in a band gap shift towards the visible spectrum enabling Ag-TiO 2 to exhibit photocatalytic properties when exposed to visible light. Small quantities of Ag-TiO 2 were able to produce a bactericidal effect when in contact with S. mutans under visible light conditions. When incorporated into the bulk of an epoxy resin, the photocatalytic properties of the Ag-TiO 2 particles were significantly reduced. However, a potent bactericidal effect was still achieved against S. mutans. Ag-TiO 2 filled resin shows promising antimicrobial properties, which could potentially be used clinically. Copyright © 2016. Published by Elsevier Ltd.

  1. Effects of Silver and Other Metals on the Cytoskeleton

    Science.gov (United States)

    Conrad, Gary W.

    1997-01-01

    Directly or indirectly, trace concentrations of silver ion (Ag(+)) stabilize microtubules (Conrad, A.H., et al. Cell Motil. & Cytoskel. 27:117-132), as does taxol (Conrad, A.H., et al. J. Exp. Zool. 262:154-165), an effect with major consequences for cellular shape changes and development. Polymerization of microtubules is gravity-sensitive (Tabony and Job, Proc. Natl. Acad. Sci. USA 89:6948-6952), so trace amounts of Ag(+) may alter cellular ability to respond to gravity. If Ag electrolysis is used to purify water on NASA space vehicles, plants and animals/astronauts will be exposed continuously to Ag(+), a regimen with unknown cellular and developmental consequences. Fertilized eggs of the marine mudsnail, Ilyanassa obsoleta, are the cells in which the effects of A(+) on microtubules were discovered. They distribute visible cytoplasmic contents according to gravity and contain cytoplasmic morphogenetic determinants for heart development. The objectives are to determine if the effects of Ag(+), AU(3+), (of biosensor relevance), or Gd(3+) (inhibitor of some stretch-activated ion channels) on the cytoskeleton (in the presence and absence of mechanical loading) will affect cellular responses to gravity.

  2. Cost-Effectiveness Analysis in Comparing Alginate Silver Dressing with Silver Zinc Sulfadiazine Cream in the Treatment of Pressure Ulcers

    Directory of Open Access Journals (Sweden)

    Apirag Chuangsuwanich

    2013-09-01

    Full Text Available BackgroundThe treatment of pressure ulcers is complicated, given the various wound dressing products available. The cost of different treatments varies and the cost-effectiveness of each product has not been thoroughly evaluated. We compare two wound dressing protocols-alginate silver dressing (AlSD and silver zinc sulfadiazine cream (AgZnSD with regard to wound healing and cost-effectiveness.MethodsPatients with grade III or IV sacral or trochanteric pressure ulcers were eligible for this prospective, randomized controlled trial. The patients were randomized to receive one of the two dressings for an eight-week period. The criteria of efficacy were based on the Pressure Ulcer Scale for Healing (PUSH scoring tool. The cost of treatment was also assessed.ResultsTwenty patients (12 women and 8 men were randomly assigned to receive either AlSD (n=10 or AgZnSD cream (n=10. The demographic data and wound characteristics were comparable in the two groups. The two groups showed no significant difference in the reduction of PUSH score, wound size, or volume of exudate. The tissue type score was significantly lower in the AlSD group (3.15±0.68-1.85±0.68 vs. 2.73±0.79-2.2±0.41; P=0.015. The cost of treatment was significantly lower in the AlSD group (377.17 vs. 467.74 USD, respectively; P<0.0001.ConclusionsAlginate silver dressing could be effectively used in the treatment of grade III and IV pressure ulcers. It can improve wound tissue characteristics and is cost-effective.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-06-03

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

  5. Isotope effect of impurity diffusion of cadmium in silver

    International Nuclear Information System (INIS)

    Rockosch, H.J.; Herzig, C.

    1984-01-01

    The isotope effect of impurity diffusion of cadmium in silver single crystals was measured with the radioisotopes 115 Cd/ 109 Cd by gamma spectrometry. As a mean value E = 0.37 at T = 1060 K was obtained. The correlation factor f /SUB Cd/ = 0.41 is in disagreement with previous results of other investigators due to their unfavourable experimental approach. The present value of f /SUB Cd/ , however, is consistent with those of In and Sn in Ag. A comparison with the corresponding correlation factors in the copper solvent reveals a distinct influence of lattice perturbations because of the different atomic volumes of the solvents. Since the size effect is neglected in the electrostatic diffusion model, the agreement with this model is only qualitative. The frequency ratios for vacancy jumps were calculated. The free binding enthalpy of the vacancy-impurity complex was estimated to be Δg /SUB Cd/ = -0.064 eV. This value is smaller than those for In and Sn in Ag and complies with the relative diffusivities of these impurities in Ag

  6. Silver nanoparticles: mechanism of antimicrobial action, synthesis, medical applications, and toxicity effects

    Science.gov (United States)

    Prabhu, Sukumaran; Poulose, Eldho K.

    2012-10-01

    Silver nanoparticles are nanoparticles of silver which are in the range of 1 and 100 nm in size. Silver nanoparticles have unique properties which help in molecular diagnostics, in therapies, as well as in devices that are used in several medical procedures. The major methods used for silver nanoparticle synthesis are the physical and chemical methods. The problem with the chemical and physical methods is that the synthesis is expensive and can also have toxic substances absorbed onto them. To overcome this, the biological method provides a feasible alternative. The major biological systems involved in this are bacteria, fungi, and plant extracts. The major applications of silver nanoparticles in the medical field include diagnostic applications and therapeutic applications. In most of the therapeutic applications, it is the antimicrobial property that is being majorly explored, though the anti-inflammatory property has its fair share of applications. Though silver nanoparticles are rampantly used in many medical procedures and devices as well as in various biological fields, they have their drawbacks due to nanotoxicity. This review provides a comprehensive view on the mechanism of action, production, applications in the medical field, and the health and environmental concerns that are allegedly caused due to these nanoparticles. The focus is on effective and efficient synthesis of silver nanoparticles while exploring their various prospective applications besides trying to understand the current scenario in the debates on the toxicity concerns these nanoparticles pose.

  7. Green Synthesis and Antibacterial Effect of Silver Nanoparticles Using Vitex Negundo L.

    Directory of Open Access Journals (Sweden)

    Fatima Abu Bakar

    2011-08-01

    Full Text Available Different biological methods are gaining recognition for the production of silver nanoparticles (Ag-NPs due to their multiple applications. One of the most important applications of Ag-NPs is their use as an anti-bacterial agent. The use of plants in the synthesis of nanoparticles emerges as a cost effective and eco-friendly approach. In this study the biosynthesis of silver nanoparticles using Vitex negundo L. extract and its antimicrobial properties has been reported. The resulting silver particles are characterized using transmission electron microscopy (TEM, X-ray diffraction (XRD and UV–Visible (UV-Vis spectroscopic techniques. The TEM study showed the formation of silver nanoparticles in the 10–30 nm range and average 18.2 nm in size. The XRD study showed that the particles are crystalline in nature, with a face centered cubic (fcc structure. The silver nanoparticles showed the antimicrobial activity against Gram positive and Gram negative bacteria. Vitex negundo L. was found to display strong potential for the synthesis of silver nanoparticles as antimicrobial agents by rapid reduction of silver ions (Ag+ to Ag0.

  8. 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...

  9. Characterization of a silver-incorporated calcium phosphate film by RBS and its antimicrobial effects

    International Nuclear Information System (INIS)

    Han, I-H; Lee, I-S; Song, J-H; Lee, M-H; Park, J-C; Lee, G-H; Sun, X-D; Chung, S-M

    2007-01-01

    A thin calcium phosphate film was synthesized on both commercially pure Ti and Si wafers by electron beam evaporation of hydroxyapatite as an evaporant with simultaneous Ar ion beam bombardments. Silver was introduced into an ion-beam-assisted deposition of a calcium phosphate thin film for antimicrobial effect. The amount of incorporated silver ions was controlled by immersing calcium-phosphate-coated samples in different AgNO 3 concentrations, and Rutherford backscattering spectrometry (RBS) was employed to measure the amounts of substituted silver. The higher concentration of silver in the calcium phosphate film was more effective in reducing the bacteria of Escherichia coli ATCC 8739 and Streptococcus mutans OMZ 65 on contact with respect to controls

  10. Characterization of a silver-incorporated calcium phosphate film by RBS and its antimicrobial effects

    Energy Technology Data Exchange (ETDEWEB)

    Han, I-H [Institute of Physics and Applied Physics, and Atomic-Scale Surface Science Research Center, Yonsei University, Seou1 120-749 (Korea, Republic of); Lee, I-S [Institute of Physics and Applied Physics, and Atomic-Scale Surface Science Research Center, Yonsei University, Seou1 120-749 (Korea, Republic of); Song, J-H [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Lee, M-H [Department of Medical Engineering, Yonsei University, Seoul 120-752 (Korea, Republic of); Park, J-C [Department of Medical Engineering, Yonsei University, Seoul 120-752 (Korea, Republic of); Lee, G-H [Korea Institute of Machinery and Materials, Chang-Won 641-010 (Korea, Republic of); Sun, X-D [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Chung, S-M [Implantium Research Center, Seoul 135-879 (Korea, Republic of)

    2007-09-15

    A thin calcium phosphate film was synthesized on both commercially pure Ti and Si wafers by electron beam evaporation of hydroxyapatite as an evaporant with simultaneous Ar ion beam bombardments. Silver was introduced into an ion-beam-assisted deposition of a calcium phosphate thin film for antimicrobial effect. The amount of incorporated silver ions was controlled by immersing calcium-phosphate-coated samples in different AgNO{sub 3} concentrations, and Rutherford backscattering spectrometry (RBS) was employed to measure the amounts of substituted silver. The higher concentration of silver in the calcium phosphate film was more effective in reducing the bacteria of Escherichia coli ATCC 8739 and Streptococcus mutans OMZ 65 on contact with respect to controls.

  11. Cytotoxic Effect on Cancerous Cell Lines by Biologically Synthesized Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Balaji Kulandaivelu

    Full Text Available The biosynthesis of nanoparticles has been proposed as an environmental friendly and cost effective alternative to chemical and physical methods. Silver nanoparticles are biologically synthesized and characterized were used in the study. The invitro cytotoxic effect of biologically synthesized silver nanoparticles against MCF-7 cancer cell lines were assessed. The cytotoxic effects of the silver nanoparticles could significantly inhibited MCF-7 cancer cell lines proliferation in a time and concentration-dependent manner by MTT assay. Acridine orange, ethidium bromide (AO/EB dual staining, caspase-3 and DNA fragmentation assays were carried out using various concentrations of silver nanoparticles ranging from 1 to 100 μg/mL. At 100 μg/mL concentration, the silver nanoparticles exhibited significant cytotoxic effects and the apoptotic features were confirmed through caspase-3 activation and DNA fragmentation assays. Western blot analysis has revealed that nanoparticle was able to induce cytochrome c release from the mitochondria, which was initiated by the inhibition of Bcl-2 and activation of Bax. Thus, the results of the present study indicate that biologically synthesized silver nanoparticles might be used to treat breast cancer. The present studies suggest that these nanoparticles could be a new potential adjuvant chemotherapeutic and chemo preventive agent against cytotoxic cells. However, it necessitates clinical studies to ascertain their potential as anticancer agents.

  12. effects of sulphur addition on addition on and mechanical properties

    African Journals Online (AJOL)

    User

    on the microstructure and mechanical properties of sand cast been investigated ... owed that the addition of sulphur to Al-12wt%Si alloy. 12wt%Si alloy .... 28 materials. 29. Element. Aluminum. Silicon. Al. Si. Ca. Fe. Cu. Zn. Mn. Mg. Cr. B. 99.71.

  13. High-negative effective refractive index of silver nanoparticles system in nanocomposite films

    Science.gov (United States)

    Altunin, Konstantin K.; Gadomsky, Oleg N.

    2012-03-01

    We have proved on the basis of the experimental optical reflection and transmission spectra of the nanocomposite film of poly(methyl methacrylate) with silver nanoparticles that (PMMA + Ag) nanocomposite films have quasi-zero refractive indices in the optical wavelength range. We show that to achieve quasi-zero values of the complex index of refraction of composite materials is necessary to achieve high-negative effective refractive index in the system of spherical silver nanoparticles.

  14. Effectiveness of silver diamine fluoride in caries prevention and arrest: a systematic literature review

    OpenAIRE

    Contreras, Violeta; Toro, Milagros J.; Elías-Boneta, Augusto R.; Encarnación-Burgos, Angeliz

    2017-01-01

    This study aimed to evaluate the scientific evidence regarding the effectiveness of silver diamine fluoride (SDF) in preventing and arresting caries in the primary dentition and permanent first molars. A systematic review (SR) was performed by 2 independent reviewers using 3 electronic databases (PubMed, ScienceDirect, and Scopus). The database search employed the following key words: “topical fluorides” AND “children” AND “clinical trials”; “topical fluorides” OR “silver diamine fluoride” AN...

  15. Effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit

    OpenAIRE

    Peng Xi; Yan Li; Xiaojin Ge; Dandan Liu; Mingsan Miao

    2018-01-01

    Objective: Observing the effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit. Method: We prepared boiling water scalded rabbits with deep II degree scald models and applied high, medium and low doses of nano-silver hydrogel coating film for different time and area. Then we compared the difference of burned paper weight before administration and after administration model burns, burn local skin irritation points infection, skin crusting and scabs from th...

  16. Effect of non-stationary current regimes on the morphology of silver electrodeposits

    OpenAIRE

    Dimitrov, Aleksandar; Paunovic, Perica; Popovski, Orce

    2009-01-01

    Abstract: This work is concerned with the use of reverse current regimes in order to form small-grained and compact silver deposits during the electrorefining process. Several parameters were varied, i.e., i) anodic overpotential,ii) cathodic vs. anodic time ratio and iii) duration of the anodic pulse. After optimization of these parameters, phosphate ions were added and the electrolyte was stirred. The effects of a rise of the anodic overpotential on the grain sizes of the silver depos...

  17. Photonic band gap effect and structural color from silver nanoparticle gelatin emulsion

    Science.gov (United States)

    Kok, Mang Hin; Ma, Rui; Lee, Jeffrey Chi Wai; Tam, Wing Yim; Chan, C. T.; Sheng, Ping; Cheah, Kok Wai

    2005-10-01

    We have fabricated planar structures of silver nanoparticles in monochromatic gelatin emulsion with a continuous spacing ranging from 0.15-0.40 micron using a two-beam interference of a single laser source. Our planar holograms display a colorful “rainbow” pattern and photonic bandgaps covering the visible and IR ranges. We model the planar silver nanoparticle-gelatin composite system using an effective medium approach and good agreement is obtained between theory and experiment.

  18. 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.

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

    Science.gov (United States)

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

    2015-01-21

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

  20. Synthesis of pure colloidal silver nanoparticles with high electroconductivity for printed electronic circuits: the effect of amines on their formation in aqueous media.

    Science.gov (United States)

    Natsuki, Jun; Abe, Takao

    2011-07-01

    This paper describes a practical and convenient method to prepare stable colloidal silver nanoparticles for use in printed electronic circuits. The method uses a dispersant and two kinds of reducing agents including 2-(dimethylamino) ethanol (DMAE), which play important roles in the reduction of silver ions in an aqueous medium. The effect of DMAE and dispersant, as well as the factors affecting particle size and morphology are investigated. In the formation of the silver nanoparticles, reduction occurs rapidly at room temperature and the silver particles can be separated easily from the mixture in a short time. In addition, organic solvents are not used. Pure, small and relatively uniform particles with a diameter less than 10 nm can be obtained that exhibit high electroconductivity. The silver nanoparticles are stable, and can be isolated as a dried powder that can be fully redispersed in deionized water. This method of producing colloidal silver nanoparticles will find practical use in electronics applications. Copyright © 2011 Elsevier Inc. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-05

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

  2. [Effect of biochar addition on soil evaporation.

    Science.gov (United States)

    Xu, Jian; Niu, Wen Quan; Zhang, Ming Zhi; Li, Yuan; Lyu, Wang; Li, Kang-Yong; Zou, Xiao-Yang; Liang, Bo-Hui

    2016-11-18

    In order to determine the rational amount of biochar application and its effect on soil hydrological processes in arid area, soil column experiments were conducted in the laboratory using three biochar additions (5%, 10% and 15%) and four different biochar types (devaporation. The results showed that the addition of biochar could change the phreatic water recharge, soil water-holding capacity, capillary water upward movement and soil evaporation obviously. But the effects were different depending on the type of biochar raw material and the size of particle. The phreatic water recharge increased with the increasing amount of biochar addition. The addition of biochar could obviously enlarge the soil water-holding capacity and promote the capillary water upward movement rate. This effect was greater when using the material of bamboo charcoal compared with using wood charcoal, while biochar with small particle size had greater impact than that with big particle size. The biochar could effectively restrain the soil evaporation at a low addition amount (5%). But it definitely promoted the soil evaporation if the addition amount was very high. In arid area, biochar addition in appropriate amount could improve soil water retention capacity.

  3. Modelling the physico-chemical effect of silver electrorefining as effect of temperature, free acid, silver, copper and lead concentrations

    Science.gov (United States)

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

    2017-01-01

    The study of electrolyte bath properties is essential for the improvement of silver electrolysis based processes. The paper outlines investigations into suitable models for the calculation of physico-chemical properties with the emphasis placed on conductivity, density and viscosity. Measurements were conducted within the industrial operation parameters used for silver electrolytes and the results indicate that these type of industrial electrolytes have an operating conductivity within the range of 60-140 mS/cm, density of 1.05-1.14 g/cm3 and a viscosity of 0.75-0.91 mm2/s. A representative model for each of these properties was proposed in order to calculate the conductivity, density and viscosity of silver electrolyte. From the evaluation of models, it was determined that all models have R2 (accuracy of fit) and Q2 (accuracy of prediction) values above 0.9 and thus can be regarded as excellent models.

  4. Effect of salinity on growth of juvenile silver kob, Argyrosomus ...

    African Journals Online (AJOL)

    We conclude that silver kob perform at least as well at reduced salinities as in full strength seawater. This could lead to significant cost savings when rearing fish inland using artificial seawater. Keywords: fish physiology; mariculture; mulloway; osmolality; salinity tolerance. African Journal of Aquatic Science 2008, 33(2): ...

  5. Antibacterial effects of silver-doped hydroxyapatite thin films sputter deposited on titanium

    International Nuclear Information System (INIS)

    Trujillo, Nathan A.; Oldinski, Rachael A.; Ma, Hongyan; Bryers, James D.; Williams, John D.; Popat, Ketul C.

    2012-01-01

    Since many orthopedic implants fail as a result of loosening, wear, and inflammation caused by repeated loading on the joints, coatings such as hydroxyapatite (HAp) on titanium with a unique topography have been shown to improve the interface between the implant and the natural tissue. Another serious problem with long-term or ideally permanent implants is infection. It is important to prevent initial bacterial colonization as existing colonies have the potential to become encased in an extracellular matrix polymer (biofilm) that is resistant to antibacterial agents. In this study, plasma-based ion implantation was used to examine the effects of pre-etching on plain titanium. Topographical changes to the titanium samples were examined and compared via scanning electron microscopy. Hydroxyapatite and silver-doped hydroxyapatite thin films were then sputter deposited on titanium substrates etched at − 700 eV. For silver-doped films, two concentrations of silver (∼ 0.5 wt.% and ∼ 1.5 wt.%) were used. Silver concentrations in the film were determined using energy dispersive X-ray spectroscopy. Hydroxyapatite film thicknesses were determined by measuring the surface profile using contact profilometry. Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion studies were performed on plain titanium, titanium coated with hydroxyapatite, titanium coated with ∼ 0.5 wt.% silver-doped hydroxyapatite, and titanium coated with ∼ 1.5 wt.% silver-doped hydroxyapatite. Results indicate that less bacteria adhered to surfaces containing hydroxyapatite and silver; further, as the hydroxyapatite films delaminated, silver ions were released which killed bacteria in suspension. - Highlights: ► We have developed a combination of plasma-based ion implantation and ion beam sputter deposition technique. ► Silver-doped hydroxyapatite thin films on titanium were developed. ► The thin films showed the ability to control the concentration of silver that is doped within the

  6. Effect of the application of silver nitrate on antioxidant status in watermelon plants

    International Nuclear Information System (INIS)

    Fuente, M.C.D.L.; Rangel, A.S.

    2014-01-01

    In this experiment we studied the absorption of silver by watermelon plants of the variety Jubilee, as well as the effect on the lycopene content and antioxidant status. The treatments were based on a silver nitrate solution of different concentrations: 0, 30, 60, 90 and 200 mg L-1, applied at intervals of 8 days throughout the crop cycle. The determination of silver content was performed by atomic emission spectroscopy (AES), whereas the detection of the silver particles inside plant tissues was carried out by means of scanning electron microscopy (SEM). By analyzing the data obtained in the experiment, a statistically significant difference was detected between treatments and between different plant organs. There was a greater accumulation of silver in the roots of plants and the content was positively related to the rate of application of AgNO/sub 3/. The antioxidant status analyzed in the fruits increased three times in the plants exposed to 30 mg L-1 AgNO/sub 3/ concentration. Meanwhile, lycopene content decreased with increased concentration of silver in solution and showed the highest content with 30 mg L-1 AgNO/sub 3/. (author)

  7. Cytoprotective effect of glutaraldehyde erythropoietin on HEK293 kidney cells after silver nanoparticle exposure

    Directory of Open Access Journals (Sweden)

    Sooklert K

    2016-02-01

    Full Text Available Kanidta Sooklert,1,2 Supreecha Chattong,3 Krissanapong Manotham,3 Chawikan Boonwong,1 I-yanut Klaharn,1 Depicha Jindatip,4 Amornpun Sereemaspun1,4 1Nanobiomedicine Laboratory, Department of Anatomy, Faculty of Medicine, 2Inter-Department Program of Biomedical Sciences, Faculty of Graduate School, Chulalongkorn University, 3Renal Unit, Department of Medicine, Lerdsin General Hospital, 4Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, ThailandAbstract: The toxic effects from exposure to silver nanoparticles (AgNPs, which are broadly present in many consumer products, have long raised concerns. Many studies have focused on the mechanisms of nanosilver, which cause toxicity in human cells, but little is known about prevention of this type of injury. This study investigated the in vitro effects of glutaraldehyde erythropoietin (GEPO, a cytoprotective compound derived from erythropoietin, in terms of cell protection against AgNP-induced injury. HEK293 cells were pretreated with or without GEPO before administration of AgNPs. The protective effects of GEPO in this cell line were assessed by the percentage of viable cells, alterations of cell morphology, and the proliferative capability of the cells. In addition, we assessed the role of GEPO in lowering cellular oxidative stress and regulating expression of the anti-apoptotic protein Bcl2. The results showed rescue effects on the percentage of viable and proliferative cells among GEPO pretreated cells. Pretreatment with GEPO maintained the normal cell shape and ultrastructural morphology. Moreover, GEPO reduced the generation of reactive oxygen species in cells and activated expression of Bcl2, which are the major mechanisms in protection against cellular toxicity induced by AgNPs. In conclusion, our study showed that the cytotoxic effects from exposure to AgNPs can be prevented by GEPO. Keywords: glutaraldehyde erythropoietin, silver nanoparticles, cytoprotection

  8. Effect of silver nano particles on flexural strength of acrylic resins.

    Science.gov (United States)

    Sodagar, Ahmad; Kassaee, Mohammad Zaman; Akhavan, Azam; Javadi, Negar; Arab, Sepideh; Kharazifard, Mohammad Javad

    2012-04-01

    Poly(methyl methacrylate), PMMA, is widely used for fabrication of removable orthodontic appliances. Silver nano particles (AgNps) have been added to PMMA because of their antimicrobial properties. The aim of this study is to investigate the effect of AgNps on the flexural strength of PMMA. Acrylic liquid containing 0.05% and 0.2% AgNps was prepared for two kinds of acrylic resins: Rapid Repair &Selecta Plus. Two groups without AgNps were used as control groups. For each one, flexural strength was investigated via Three Point Bending method for the 15 acrylic blocks. Two-way ANOVA, one way ANOVA and Tukey tests were used for statistical analysis. Rapid Repair without AgNps showed the highest flexural strength. Addition of 0.05% AgNps to Rapid Repair, significantly decreased its flexural strength while, continuing the addition up to 0.2% increased it nearly up to its primary level. In contrast, addition of AgNps to Selecta Plus increased its flexural strength but addition of 0.05% nano particles was more effective than 0.2%. The effect of AgNps on flexural strength of PMMA depends on several factors including the type of acrylics and the concentrations of nano particles. Copyright © 2011 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

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

    OpenAIRE

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

    2016-01-01

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

  10. 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.

  11. Additive effects in radiation grafting and curing

    International Nuclear Information System (INIS)

    Viengkhou, V.; Ng, L.

    1996-01-01

    Full text: Detailed studies on the accelerative effect of novel additives in radiation grafting and curing using acrylated monomer/oligomer systems have been performed in the presence of ionising radiation and UV as sources. Methyl methacrylate (MMA) is used as typical monomer for these grafting studies in the presence of the additives with model backbone polymers, cellulose and propropylene. Additives which have been found to accelerate these grafting processes are: mineral acid, occlusion compounds like urea, thermal initiators and photoinitiators as well as multifunctional monomers such as multifunctional acrylates. The results from irradiation with gamma rays have also been compared with irradiation from a 90W UV lamp. The role of the above additives in accelerating the analogous process of radiation curing has been investigated. Acrylated urethanes, epoxies and polyesters are used as oligomers together with acrylated monomers in this work with uv lamps of 300 watts/inch as radiation source. In the UV curing process bonding between film and substrate is usually due to physical forces. In the present work the presence of additives are shown to influence the occurrence of concurrent grafting during cure thus affecting the nature of the bonding of the cured film. The conditions under which concurrent grafting with UV can occur will be examined. A mechanism for accelerative effect of these additives in both grafting and curing processes has been proposed involving radiation effects and partitioning phenomena

  12. Non-additive Effects in Genomic Selection

    Directory of Open Access Journals (Sweden)

    Luis Varona

    2018-03-01

    Full Text Available In the last decade, genomic selection has become a standard in the genetic evaluation of livestock populations. However, most procedures for the implementation of genomic selection only consider the additive effects associated with SNP (Single Nucleotide Polymorphism markers used to calculate the prediction of the breeding values of candidates for selection. Nevertheless, the availability of estimates of non-additive effects is of interest because: (i they contribute to an increase in the accuracy of the prediction of breeding values and the genetic response; (ii they allow the definition of mate allocation procedures between candidates for selection; and (iii they can be used to enhance non-additive genetic variation through the definition of appropriate crossbreeding or purebred breeding schemes. This study presents a review of methods for the incorporation of non-additive genetic effects into genomic selection procedures and their potential applications in the prediction of future performance, mate allocation, crossbreeding, and purebred selection. The work concludes with a brief outline of some ideas for future lines of that may help the standard inclusion of non-additive effects in genomic selection.

  13. Cost-Effectiveness Analysis in Comparing Alginate Silver Dressing with Silver Zinc Sulfadiazine Cream in the Treatment of Pressure Ulcers

    Directory of Open Access Journals (Sweden)

    Apirag Chuangsuwanich

    2013-09-01

    Full Text Available Background The treatment of pressure ulcers is complicated, given the various wound dressingproducts available. The cost of different treatments varies and the cost-effectiveness of eachproduct has not been thoroughly evaluated. We compare two wound dressing protocolsalginatesilver dressing (AlSD and silver zinc sulfadiazine cream (AgZnSD with regard towound healing and cost-effectivenessMethods Patients with grade III or IV sacral or trochanteric pressure ulcers were eligible forthis prospective, randomized controlled trial. The patients were randomized to receive oneof the two dressings for an eight-week period. The criteria of efficacy were based on thePressure Ulcer Scale for Healing (PUSH scoring tool. The cost of treatment was also assessed.Results Twenty patients (12 women and 8 men were randomly assigned to receive eitherAlSD (n=10 or AgZnSD cream (n=10. The demographic data and wound characteristics werecomparable in the two groups. The two groups showed no significant difference in the reductionof PUSH score, wound size, or volume of exudate. The tissue type score was significantlylower in the AlSD group (3.15±0.68-1.85±0.68 vs. 2.73±0.79-2.2±0.41; P=0.015. The costof treatment was significantly lower in the AlSD group (377.17 vs. 467.74 USD, respectively;P<0.0001.Conclusions Alginate silver dressing could be effectively used in the treatment of grade IIIand IV pressure ulcers. It can improve wound tissue characteristics and is cost-effective.

  14. Bacterial transmission from lens storage cases to contact lenses-Effects of lens care solutions and silver impregnation of cases.

    Science.gov (United States)

    Vermeltfoort, Pit B J; Hooymans, Johanna M M; Busscher, Henk J; van der Mei, Henny C

    2008-10-01

    The killing efficacies of multipurpose lens care solutions on planktonic and biofilm bacteria grown in polypropylene contact lens storage cases with and without silver impregnation and effects on bacterial transmission from storage cases to silicone hydrogel contact lenses were investigated. For transmission studies, biofilms of Staphylococcus aureus 835 or Pseudomonas aeruginosa no. 3 were grown on lens storage cases and incubated with a contact lens in different multipurpose lens care solutions (Opti-Free(R)Express(R), ReNu(R) MultiPlus(R), and SoloCare Aquatrade mark) or 0.9% NaCl. In addition, planktonic bacteria were directly suspended in multipurpose solutions and their killing efficacies were determined. The numbers of transmitted live and dead bacteria on the lenses were measured using a combination of plate counting and fluorescence microscopy. The highest killing efficacies were shown by Opti-Free(R) Express(R) for planktonic as well as for biofilm bacteria. Silver impregnation of lens cases in combination with the prescribed solution increased the killing efficacy for P. aeruginosa in biofilms, whereas effects for S. aureus were minor. Lowest numbers of live and dead bacteria were transmitted to a lens in Opti-Free(R) Express(R) multipurpose solution, with no significant differences between lens types and no effects of silver impregnation. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008. (c) 2008 Wiley Periodicals, Inc.

  15. Effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit

    Directory of Open Access Journals (Sweden)

    Peng Xi

    2018-05-01

    Full Text Available Objective: Observing the effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit. Method: We prepared boiling water scalded rabbits with deep II degree scald models and applied high, medium and low doses of nano-silver hydrogel coating film for different time and area. Then we compared the difference of burned paper weight before administration and after administration model burns, burn local skin irritation points infection, skin crusting and scabs from the time, and the impact of local skin tissue morphology. Result: Rabbits deep II degree burn model successful modeling; on day 12, 18, high, medium and low doses of nano-silver hydrogel coating film significantly reduced skin irritation of rabbits infected with the integral value (P < 0.01, P < 0.05; high, medium and low doses of nano-silver hydrogel coating film group significantly decreased skin irritation, infection integral value (P < 0.01, P < 0.05; high, medium and low doses of nano-silver hydrogel coating film significantly reduced film rabbits’ scalded skin crusting time (P < 0.01, significantly shortened the rabbit skin burns from the scab time (P < 0.01, and significantly improved the treatment of skin diseases in rabbits scald model change (P < 0.01, P < 0.05. Conclusion: The nano-silver hydrogel coating film on the deep partial thickness burns has a significant therapeutic effect; external use has a significant role in wound healing. Keywords: Nano-silver hydrogel coating film, Deep degree burns, Topical, Rabbits

  16. Biosynthesis, antimicrobial and cytotoxic effect of silver nanoparticles using a novel Nocardiopsis sp. MBRC-1.

    Science.gov (United States)

    Manivasagan, Panchanathan; Venkatesan, Jayachandran; Senthilkumar, Kalimuthu; Sivakumar, Kannan; Kim, Se-Kwon

    2013-01-01

    The biosynthesis of nanoparticles has been proposed as a cost effective environmental friendly alternative to chemical and physical methods. Microbial synthesis of nanoparticles is under exploration due to wide biomedical applications, research interest in nanotechnology and microbial biotechnology. In the present study, an ecofriendly process for the synthesis of nanoparticles using a novel Nocardiopsis sp. MBRC-1 has been attempted. We used culture supernatant of Nocardiopsis sp. MBRC-1 for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Nocardiopsis sp. MBRC-1 culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, FE-SEM, EDX, FTIR, and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 420 nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were spherical in shape with an average particle size of 45 ± 0.15 nm. The EDX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FTIR analysis revealed that the protein component in the form of enzyme nitrate reductase produced by the isolate in the culture supernatant may be responsible for reduction and as capping agents. The XRD spectrum showed the characteristic Bragg peaks of 1 2 3, 2 0 4, 0 4 3, 1 4 4, and 3 1 1 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against bacteria and fungi. Cytotoxicity of biosynthesized AgNPs against in vitro human cervical cancer cell line (HeLa) showed a dose-response activity. IC50 value was found to be 200 μg/mL of AgNPs against HeLa cancer cells. Further studies are needed to elucidate the toxicity and the mechanism involved with antimicrobial and anticancer activity of the synthesized AgNPs as

  17. THE POSSIBILITY OF CREATING MULTIFUNCTIONAL SILVER-CONTAINING DRUGS WITH DETOXIFYING EFFECT

    Directory of Open Access Journals (Sweden)

    T. V. Popova

    2017-01-01

    Full Text Available Modern technology and the level of fundamental studies allow us to create the medical sorbents with the predetermined structural, mechanical and adsorptional properties. Sorption materials are interesting not only as detoxicants that are used to remove toxic agents from the liquid media, but also as carriers for a delivery in zones a therapeutic effect of biologically active substances. The aim of this work is the substantiation of structure of the multifunctional drug with anti-bacterial and detoxifying effects due to the complex of silver and the sorption component – alumina-silica-containing sorbent. Materials and methods. We used physico-chemical (sorption activity of methylene blue dye, specific surface, pH in contact with water, atomic emission spectrometry with inductively coupled plasma and pharmaceutical methods (bulk density, dissolution test for solid dosage forms. Results and discussion. The two-stage method of immobilization of a complex of silver and water repellent on the surface sorptionmatrix was justified. The sample of the optimum composition of silver-containing drugs was selected: aluminium oxide-hydroxide – 99.2%, clustered silver (Argovit – C – 2% – 0.3 %, based on silver and subsidiary substance (repellents – brand PMS P – 841 – 0.5 %. The output of silver into the solution from the specified sample composition for 8 hours did not exceed 1,6 ± 0,3%, the value of specific surface area of 90 m2/ g, the value of pH to 8.1 ± 0.02, bulk density 1.12 ± 0.11 g/cm3. Conclusion. An experimentally substantiated composition of silver-containing drug AlSi/Ag was received, a comprehensive scientific data of its physico-chemical and technological properties were obtained.

  18. Silver nanoparticle-E. coli colloidal interaction in water and effect on E. coli survival.

    Science.gov (United States)

    Dror-Ehre, A; Mamane, H; Belenkova, T; Markovich, G; Adin, A

    2009-11-15

    Silver nanoparticles exhibit antibacterial properties via bacterial inactivation and growth inhibition. The mechanism is not yet completely understood. This work was aimed at elucidating the effect of silver nanoparticles on inactivation of Escherichia coli, by studying particle-particle interactions in aqueous suspensions. Stable, molecularly capped, positively or negatively charged silver nanoparticles were mixed at 1 to 60microgmL(-1) with suspended E. coli cells to examine their effect on inactivation of the bacteria. Gold nanoparticles with the same surfactant were used as a control, being of similar size but made up of a presumably inert metal. Log reduction of 5log(10) and complete inactivation were obtained with the silver nanoparticles while the gold nanoparticles did not show any inactivation ability. The effect of molecularly capped nanoparticles on E. coli survival was dependent on particle number. Log reduction of E. coli was associated with the ratio between the number of nanoparticles and the initial bacterial cell count. Electrostatic attraction or repulsion mechanisms in silver nanoparticle-E. coli cell interactions did not contribute to the inactivation process.

  19. The effect of nano-silver packaging in increasing the shelf life of nuts: An in vitro model.

    Science.gov (United States)

    Tavakoli, Hamidreza; Rastegar, Hossein; Taherian, Mahdi; Samadi, Mohammad; Rostami, Hossein

    2017-10-20

    Nano packaging is currently one of the most important topics in food packaging technologies. The aim of the application of this technology in food packaging is increasing shelf life of foods by preventing internal and external corruption and microbial contaminations. Use of silver nanoparticles in food packaging has recently attracted much attention. The aim of this study was to investigate the effect of nano-silver packaging in increasing the shelf life packages of nuts in an In vitro model. In this experimental study, the effects of different nano-silver concentrations (0, 1, 2 and 3 percent) on biological and chemical properties of 432 samples of nuts including walnuts, hazelnuts, almonds and pistachios were evaluated during 0, 3, 6, 9, 12, 15, 18, 21 and 24 months. In most samples, different concentrations of nano-silver (1, 2 and 3 %) significantly reduced total microbial count, mold and coliform counts compared to control group and the 3% nano-silver concentration was more effective than other concentrations (Pnano-silver concentrations were used. Nano-silver also prevented growth of mold and so prevented aflatoxin production in all treatment groups. Results of chemical and biological tests showed that the silver nanoparticles had a significant effect on increasing the shelf life of nuts. The highest shelf life belonged to pistachios, almonds, hazelnuts and walnuts with 20, 19, 18 and 18 months, respectively. The shelf life was associated with amount of silver nanoparticles. The highest antimicrobial activity was observed when 3% nano-silver concentration was used in pistachios. The shelf life of control groups in similar storage conditions were calculated for an average of 13 months. In conclusion, the results of this study demonstrate the efficacy of nano-silver packing in increasing shelf life of nuts. Hence, use of nano-silver packaging in food industry, especially in food packaging is recommended.

  20. Effects from additives on deacetylation of chitin

    International Nuclear Information System (INIS)

    Campana Filho, Sergio P.; Signini, Roberta

    2001-01-01

    Deacetylation reactions of commercial chitin were carried out in aqueous sodium hydroxide solution at 115 deg C for 6 hours. The effect from additives (sodium borohydride or anthraquinone) and of bubbling inert gas (nitrogen or argon) on the characteristics of deacetylated samples were evaluated. Average degrees of acetylation and intrinsic viscosity were determined by 1 H NMR spectroscopy and capillary viscometry, respectively. X-ray diffraction was employed to evaluate changes in crystallinity and infrared spectroscopy was used to monitor structural changes due to deacetylation. The bubbling of inert gas during the deacetylation reaction resulted in more crystalline samples of chitosan. Deacetylation carried out without any additive produced slightly more deacetylated chitosan but they were severely depolymerized. The depolymerization process was much less important when sodium borohydride was added to the reaction medium but the addition of anthraquinone and the bubbling of nitrogen, or argon, did not have any effect, this suggests that oxygen is not required for depolymerization. (author)

  1. Sintering of magnesia: effect of additives

    Indian Academy of Sciences (India)

    Effect of different additives, namely Cr2O3, Fe2O3 and TiO2, up to 2 wt% was studied on the sinter- ing and .... mental distribution of the components is shown in figure 7. It shows ... Chiang Y M, Birniand D and Kingery W 1996 Physical ceram-.

  2. Effects of gamma irradiation and silver nano particles on microbiological characteristics of saffron, using hurdle technology.

    Science.gov (United States)

    Hamid Sales, E; Motamedi Sedeh, F; Rajabifar, S

    2012-03-01

    Saffron, a plant from the Iridaceae family, is the world's most expensive spice. Gamma irradiation and silver nano particles whose uses are gradually increasing worldwide, have positive effects on preventing decay by sterilizing the microorganisms and by improving the safety without compromising the nutritional properties and sensory quality of the foods. In the present study combination effects of gamma irradiation and silver nano particles packaging on the microbial contamination of saffron were considered during storage. A combination of hurdles can ensure stability and microbial safety of foods. For this purpose, saffron samples were packaged by Poly Ethylene films that posses up to 300 ppm nano silver particles as antimicrobial agents and then irradiated in cobalt-60 irradiator (gamma cell PX30, dose rate 0.55 Gry/Sec) to 0, 1, 2,3 and 4 kGy at room temperature. The antimicrobial activities against Total Aerobic Mesophilic Bacteria, Entrobacteriace, Escherichia Coli and Clostridium Perfringines were higher in the irradiated samples, demonstrating the inhibition zone for their growth. Irradiation of the saffron samples packaged by Poly Ethylene films with nano silver particles showed the best results for decreasing microbial contamination at 2 kGy and for Poly Ethylene films without silver nano particles; it was 4 kGy.

  3. 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...

  4. 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.

  5. The anti-cancer effect of octagon and spherical silver nanoparticles on MCF-7 breast cancer cell line

    Directory of Open Access Journals (Sweden)

    Mehrdad Khatami

    2017-04-01

    Full Text Available Background: The modern science of nanotechnology is an interdisciplinary science that has contributed to advances in cancer treatment. This study was performed to evaluate the therapeutic effects of biosynthesized silver nanoparticles on breast cancer cell of line MCF-7 in vitro. Methods: This analytical study was performed in Kerman and Bam University of Medical Sciences, Bam City, Kerman Province, Iran from March 2015 to March 2016. Silver nanoparticles suspension was synthesized using palm kernel extract. The resulting silver nanoparticles were studied and characterized. The ultraviolet-visible spectroscopy and transmission electron microscopy used for screening of physicochemical properties. The average particle size of the biosynthesized silver nanoparticles was determined by transmission electron microscopy. The properties of different concentrations of synthesized silver nanoparticles (1 to 3 μg/ml and palm kernel extract (containing the same concentration of the extract was used for the synthesis of silver nanoparticles against MCF-7 human breast cancer cells were determined by MTT assay. MTT is used to assess cell viability as a function of redox potential. Actively respiring cells convert the water-soluble MTT to an insoluble purple formazan. Results: The ultraviolet-visible spectroscopy showed strong absorption peak at 429 nm. The X-ray diffraction (XRD and transmission electron microscopy (TEM images revealed the formation of silver nanoparticles with spherical and octagon shape and sizes in the range between 1-40 nm, with an average size approximately 17 nm. The anti-cancer effect of silver nanoparticles on cell viability was strongly depends on the concentration of silver nanoparticles and greatly decrease with increasing the concentration of silver nanoparticles. The IC50 amount of silver nanoparticle was 2 μg/ml. Conclusion: The biosynthesized silver nanoparticles showed a dose-dependent toxicity against MCF-7 human breast

  6. Excessive Additive Effect On Engine Oil Viscosity

    Directory of Open Access Journals (Sweden)

    Vojtěch Kumbár

    2014-01-01

    Full Text Available The main goal of this paper is excessive additive (for oil filling effect on engine oil dynamic viscosity. Research is focused to commercially distribute automotive engine oil with viscosity class 15W–40 designed for vans. There were prepared blends of new and used engine oil without and with oil additive in specific ratio according manufacturer’s recommendations. Dynamic viscosity of blends with additive was compared with pure new and pure used engine oil. The temperature dependence dynamic viscosity of samples was evaluated by using rotary viscometer with standard spindle. Concern was that the oil additive can moves engine oil of several viscosity grades up. It is able to lead to failure in the engine. Mathematical models were used for fitting experimental values of dynamic viscosity. Exponential fit function was selected, which was very accurate because the coefficient of determination R2 achieved high values (0.98–0.99. These models are able to predict viscosity behaviour blends of engine oil and additive.

  7. Diameter Effect of Silver Nanorod Arrays to Surface-enhanced Raman Scattering

    International Nuclear Information System (INIS)

    Gu, Geun Hoi; Kim, Min Young; Yoon, Hyeok Jin; Suh, Jung Sang

    2014-01-01

    The effect the diameter of silver nanorod arrays whose distance between the nanorods was uniform at 65 nm have on Surface-enhanced Raman Scattering (SERS) has been studied by varying the diameter from 28 to 51 nm. Nanorod length was fixed at approximately 62 nm, which is the optimum length for SERS by excitation with a 632.8 nm laser line. The transverse and longitudinal modes of the surface plasmon of these silver nanorods were near 400 and 630 nm, respectively. The extinction of the longitudinal mode increased with increasing nanorod diameter, while the transverse mode did not change significantly. High-quality SERS spectra of p-aminothiophenol and benzenethiol adsorbed on the tips of the silver nanorods were observed by excitation with a 632.8 nm laser line. The SERS enhancement increased with increasing nanorod diameter. We concluded that the SERS enhancement increases when the diameter of silver nanorods is increased mainly by increasing the excitation efficiency of the longitudinal mode. The enhancement factor for the silver nanorods with a 51 nm diameter was approximately 2 Χ 10 7

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  10. Enhanced photoresponsivity in organic field effect transistors by silver nanoparticles

    DEFF Research Database (Denmark)

    Linnet, Jes; Runge Walther, Anders; Albrektsen, Ole

    2017-01-01

    Organic semiconductors (OSC) such as thiophene-based oligomers exhibit useful electronic and optical properties making them applicable in photo-sensing devices. Generally, thiophene-based photodetectors exhibit a decent responsivity with a spectral sensitivity determined by the OSC's absorption...... and shape of the fabricated silver NPs, a spectrally broad enhancement is predicted, which is in agreement with the experimental results. The results show that the photoresponsivity is dominantly enhanced in a spectral region of low OSC absorption coinciding with the localized surface plasmon resonances...

  11. Effect of Diluent on Ultra-low Temperature Curable Conductive Silver Adhesive

    Science.gov (United States)

    Zhou, Xingli; Wang, Likun; Liao, Qingwei; Yan, Chao; Du, Haibo; Qin, Lei

    2018-03-01

    The ultra-low temperature curable conductive silver adhesive needed urgently for the surface conductive treatment of piezoelectric composite material. The effect of diluent acetone on ultra-low temperature curable conductive silver adhesive were investigated for surface conductive treatment of piezoelectric composite material. In order to improve the operability and extend the life of the conductive adhesive, the diluent was added to dissolve and disperse conductive adhesive. With the increase of the content of diluent, the volume resistivity of conductive adhesive decreased at first and then increased, and the shear strength increased at first and then decreased. When the acetone content is 10%, the silver flaky bonded together, arranged the neatest, the smallest gap, the most closely connected, the surface can form a complete conductive network, and the volume resistivity is 2.37 × 10-4Ω · cm, the shear strength is 5.13MPa.

  12. Kinetics of silver release from microfuel with taking into account the limited-solubility effect

    Science.gov (United States)

    Ivanov, A. S.; Rusinkevich, A. A.

    2014-12-01

    The effect of a limited solubility of silver in silicon carbide on silver release from a microfuel with a TRISO coating is studied. It is shown that a limited solubility affects substantially both concentration profiles and silver release from a microfuel over a broad range of temperatures. A procedure is developed for obtaining fission-product concentration profiles in a microfuel and graphs representing the flow and integrated release of fission products on the basis of data from neutron-physics calculations and results obtained by calculating thermodynamics with the aid of the Ivtanthermo code and kinetics with the aid of the FP-Kinetics code. This procedure takes into account a limited solubility of fission products in protective coatings of microfuel.

  13. Effect of cooling rates on bare bulk and silver wrapped pellets of Bi-2223 superconductor

    International Nuclear Information System (INIS)

    Terzioglu, C.; Oztuerk, O.; Kilic, A.; Gencer, A.; Belenli, I.

    2006-01-01

    We have examined the effect of cooling rates on oxygen content of Bi-2223 phase samples with and without silver sheating. Two sets of samples with and without silver sheating were annealed under identical conditions and cooled with rates of 10 deg. C/h, 25 deg. C/h, 50 deg. C/h, 75 deg. C/h, and 100 deg. C/h. XRD examination of the samples showed that a high percentage of Bi-2223 was obtained. Microstructure examinations were performed by scanning electron microscopy. Resistive and magnetic transitions of the samples were studied. All the reported data were discussed and related

  14. Effect of silver thiosulphate preservative on the physiology of cut carnations

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  15. Effect of non-stationary current regimes on the morphology of silver electrodeposits

    OpenAIRE

    ALEKSANDAR T. DIMITROV; PERICA PAUNOVIĆ; ORCE POPOVSKI; DRAGAN SLAVKOV; ŽELJKO KAMBEROVIĆ; SVETOMIR HADŽI JORDANOV

    2009-01-01

    This work is concerned with the use of reverse current regimes in order to form small-grained and compact silver deposits during the electro-refining process. Several parameters were varied, i.e., i) anodic overpotential, ii) cathodic vs. anodic time ratio and iii) duration of the anodic pulse. After optimization of these parameters, phosphate ions were added and the electrolyte was stirred. The effects of a rise of the anodic overpotential on the grain sizes of the silver deposit and compact...

  16. Disentangling the effects of polymer coatings on silver nanoparticle agglomeration, dissolution, and toxicity to determine mechanisms of nanotoxicity

    International Nuclear Information System (INIS)

    Zook, Justin M.; Halter, Melissa D.; Cleveland, Danielle; Long, Stephen E.

    2012-01-01

    Silver nanoparticles (AgNPs) are frequently coated with a variety of polymers, which may affect various interdependent mechanisms of toxicity or antimicrobial action, including agglomeration and dissolution rates. Here, we systematically measure how citrate, dextran, 5 and 20 kDa poly(ethylene glycol) (PEG), and poly(vinyl pyrrolidone) coatings affect AgNP agglomeration, dissolution, and toxicity. In addition, to disentangle the coatings’ effects on agglomeration from their other effects, we produce multiple stable agglomerate sizes of several of the coated ∼23 nm AgNPs ranging from singly-dispersed to mean agglomerate sizes of several hundred nanometers. These dispersions allow us to independently study the effects of agglomeration and polymer coating on dissolution rate and hemolytic toxicity. We find that both hemolytic toxicity and dissolution rate are highest for the 5 kDa PEG coating, and toxicity and dissolution rate decrease significantly with increasing agglomerate size independent of coating. This correlation between toxicity and dissolution rate suggests that both polymer coating and agglomeration may affect hemolytic toxicity largely through their effects on dissolution. Because both the AgNP dissolution rate and hemolysis decrease only moderately compared to the large increases in agglomerate size, AgNPs’ hemolytic toxicity may be caused by their large surface area and consequently high dissolution rate, rather than from other size-specific effects. At the silver concentrations used in this work, silver dissolved from AgNPs is expected to be primarily in the form of AgCl NPs, which are therefore more likely than Ag + ions to be the primary drivers of hemolytic toxicity. In addition, all AgNPs we tested are much more toxic to horse red blood cells than sheep red blood cells, highlighting the complexity of toxic responses and the need to test toxicity in multiple biological systems.

  17. Disentangling the effects of polymer coatings on silver nanoparticle agglomeration, dissolution, and toxicity to determine mechanisms of nanotoxicity

    Science.gov (United States)

    Zook, Justin M.; Halter, Melissa D.; Cleveland, Danielle; Long, Stephen E.

    2012-10-01

    Silver nanoparticles (AgNPs) are frequently coated with a variety of polymers, which may affect various interdependent mechanisms of toxicity or antimicrobial action, including agglomeration and dissolution rates. Here, we systematically measure how citrate, dextran, 5 and 20 kDa poly(ethylene glycol) (PEG), and poly(vinyl pyrrolidone) coatings affect AgNP agglomeration, dissolution, and toxicity. In addition, to disentangle the coatings' effects on agglomeration from their other effects, we produce multiple stable agglomerate sizes of several of the coated 23 nm AgNPs ranging from singly-dispersed to mean agglomerate sizes of several hundred nanometers. These dispersions allow us to independently study the effects of agglomeration and polymer coating on dissolution rate and hemolytic toxicity. We find that both hemolytic toxicity and dissolution rate are highest for the 5 kDa PEG coating, and toxicity and dissolution rate decrease significantly with increasing agglomerate size independent of coating. This correlation between toxicity and dissolution rate suggests that both polymer coating and agglomeration may affect hemolytic toxicity largely through their effects on dissolution. Because both the AgNP dissolution rate and hemolysis decrease only moderately compared to the large increases in agglomerate size, AgNPs' hemolytic toxicity may be caused by their large surface area and consequently high dissolution rate, rather than from other size-specific effects. At the silver concentrations used in this work, silver dissolved from AgNPs is expected to be primarily in the form of AgCl NPs, which are therefore more likely than Ag+ ions to be the primary drivers of hemolytic toxicity. In addition, all AgNPs we tested are much more toxic to horse red blood cells than sheep red blood cells, highlighting the complexity of toxic responses and the need to test toxicity in multiple biological systems.

  18. Disentangling the effects of polymer coatings on silver nanoparticle agglomeration, dissolution, and toxicity to determine mechanisms of nanotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Zook, Justin M., E-mail: jzook@nist.gov; Halter, Melissa D.; Cleveland, Danielle; Long, Stephen E. [National Institute of Standards and Technology, Material Measurement Laboratory (United States)

    2012-10-15

    Silver nanoparticles (AgNPs) are frequently coated with a variety of polymers, which may affect various interdependent mechanisms of toxicity or antimicrobial action, including agglomeration and dissolution rates. Here, we systematically measure how citrate, dextran, 5 and 20 kDa poly(ethylene glycol) (PEG), and poly(vinyl pyrrolidone) coatings affect AgNP agglomeration, dissolution, and toxicity. In addition, to disentangle the coatings' effects on agglomeration from their other effects, we produce multiple stable agglomerate sizes of several of the coated {approx}23 nm AgNPs ranging from singly-dispersed to mean agglomerate sizes of several hundred nanometers. These dispersions allow us to independently study the effects of agglomeration and polymer coating on dissolution rate and hemolytic toxicity. We find that both hemolytic toxicity and dissolution rate are highest for the 5 kDa PEG coating, and toxicity and dissolution rate decrease significantly with increasing agglomerate size independent of coating. This correlation between toxicity and dissolution rate suggests that both polymer coating and agglomeration may affect hemolytic toxicity largely through their effects on dissolution. Because both the AgNP dissolution rate and hemolysis decrease only moderately compared to the large increases in agglomerate size, AgNPs' hemolytic toxicity may be caused by their large surface area and consequently high dissolution rate, rather than from other size-specific effects. At the silver concentrations used in this work, silver dissolved from AgNPs is expected to be primarily in the form of AgCl NPs, which are therefore more likely than Ag{sup +} ions to be the primary drivers of hemolytic toxicity. In addition, all AgNPs we tested are much more toxic to horse red blood cells than sheep red blood cells, highlighting the complexity of toxic responses and the need to test toxicity in multiple biological systems.

  19. Effectiveness of Cerium Nitrate-Silver Sulfadiazine in the Treatment of Facial Burns: A Multicenter, Randomized, Controlled Trial

    NARCIS (Netherlands)

    Oen, I.M.M.H.; van Baar, M.E.; Middelkoop, E.; Nieuwenhuis, M.K.

    2012-01-01

    Background: The face is a very frequent site of burn injuries. This multicenter, randomized, controlled trial thus investigates the effectiveness of cerium nitrate-silver sulfadiazine in the treatment of facial burns compared with silver sulfadiazine. Methods: Adult patients with acute facial burns

  20. Effects of additives on PVG dosifilm

    Energy Technology Data Exchange (ETDEWEB)

    Wenxiu, Chen; Liu, Aiguo [Beijing Normal Univ., BJ (China). Dept. of Chemistry

    1995-03-01

    Dosifilm PVG is a new radiochromic film dosimeter composed of matrix material polyvinyl butyral (PVB), leuco malachite green (LMG) and additive halogenated organic compound (RX), etc. The control of the dose range on PVG dosifilm was examined. The addition of halogenated compounds played an important role in the radiation reaction of LMG beyond the concentration of LMG. Bromide is more effective than chloride in this system, the oxidative species are X {center_dot} and X{sub 2} {center_dot} {sup -}. PVB with N-bromosuccinimide (NBS) can induce the oxidation of LMG before irradiation. The reaction mechanism of PVG was discussed. Different linear ranges of radiation response on PVG dosifilm could be controlled by alternating the relative concentrations of halogenated compounds and LMG. (author).

  1. Effects of additives on PVG dosifilm

    International Nuclear Information System (INIS)

    Chen Wenxiu; Liu, Aiguo

    1995-01-01

    Dosifilm PVG is a new radiochromic film dosimeter composed of matrix material polyvinyl butyral (PVB), leuco malachite green (LMG) and additive halogenated organic compound (RX), etc. The control of the dose range on PVG dosifilm was examined. The addition of halogenated compounds played an important role in the radiation reaction of LMG beyond the concentration of LMG. Bromide is more effective than chloride in this system, the oxidative species are X · and X 2 · - . PVB with N-bromosuccinimide (NBS) can induce the oxidation of LMG before irradiation. The reaction mechanism of PVG was discussed. Different linear ranges of radiation response on PVG dosifilm could be controlled by alternating the relative concentrations of halogenated compounds and LMG. (author)

  2. Moderating effect of ammonia on particle growth and stability of quasi-monodisperse silver nanoparticles synthesized by the Turkevich method.

    Science.gov (United States)

    Gorup, Luiz F; Longo, Elson; Leite, Edson R; Camargo, Emerson R

    2011-08-15

    A new method to stabilize silver nanoparticles by the addition of ammonia is proposed. Colloidal dispersions of silver nanoparticles were synthesized by the Turkevich method using sodium citrate to reduce silver nitrate at high pH and at 90 °C. After approximately 12 min, a diluted ammonia solution was added to the reaction flask to form soluble diamine silver (I) complexes that played an important growth moderating role, making it possible to stabilize metallic silver nanoparticles with sizes as small as 1.6 nm after 17 min of reaction. Colloidal dispersions were characterized by UV-visible absorption spectroscopy, X-ray diffraction, and transmission electronic microscopy. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Effect of the use of silver nanocrystals and silver sulfadiazine in the management of soft tissue lesions

    Directory of Open Access Journals (Sweden)

    Tineo C

    2017-01-01

    Full Text Available Cristian Tineo,1 Cinthia M Nuñez,2–4 Ouel Sosa,1,5 Dahiana Pichardo,1 Juan Luis Hernández,1 Gustavo Collado3 1Department of Surgery, José María Cabral y Báez Regional and University Hospital (HRUJMCB, 2Department of Surgery, Dr. Arturo Grullòn University and Childrens Hospital Burn Unit (HIRUDAG, 3Department of Surgery, Santiago Metropolitan Hospital (HOMS, 4Department of Medicine, Mother and Master Pontifical and Catholic University (PUCMM, 5Department of Medicine, Santiago Thechnological University (UTESA, Santiago, Dominican Republic Background: Soft tissue lesions represent a health problem of great magnitude around the world. Multiple drugs have been used in their treatment. Silver sulfadiazine (SSD and silver nanocrystals (SNC are among the most used. The purpose of this research was to compare the effectiveness of SSD and SNC regarding the wound granulation rate, treatment time, antibiotic effect, and treatment cost and to determine the frequency of these lesions in participants of this research.Methods: Data were collected from 50 patients with soft tissue lesions in the Regional University Hospital José María Cabral y Báez (HRUJMCB, in Santiago, Dominican Republic. This study was approved by the bioethics committee of the Pontifical Catholic University Madre and Maestra (PUCMM and the HRUJMCB. Patients were followed up from August 2015 to February 2016. SPSS Statistics program was used to calculate Chi square and assess statistical significance.Results: Fifty patients were included in this study, of whom 56% had diabetic foot ulcers, 22% had vascular ulcers, and 22% had pressure ulcers. In total, 42% of the patients were treated with SSD and 58% with SNC. Granulation rate was 71.4% for SSD and 89.6% for SNC, and positive antibiotic effect was 15.9% for SSD and 25.9% for SNC. A total of 14.4% of patients treated with SSD ended their participation in the research between 8 and 14 days, 37.9% in 15–21 days, and 42.8% in

  4. An in vitro evaluation of antibacterial effect of silver nanoparticles on ...

    African Journals Online (AJOL)

    An in vitro evaluation of antibacterial effect of silver nanoparticles on Staphylococcus aureus isolated from bovine subclinical mastitis. ... African Journal of Biotechnology ... As Staphylococcus aureus is considered as a major pathogen due to its prevalence in dairy herds, contagious nature of infection, economic impact of ...

  5. Study of Supported Nickel Catalysts Prepared by Aqueous Hydrazine Method. Hydrogenating Properties and Hydrogen Storage: Support Effect. Silver Additive Effect; Catalyseurs de nickel supportes prepares par la methode de l'hydrazine aqueuse. Proprietes hydrogenantes et stockage d'hydrogene. Effet du support. Effet de l'ajout d'argent

    Energy Technology Data Exchange (ETDEWEB)

    Wojcieszak, R

    2006-06-15

    We have studied Ni or NiAg nano-particles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports ({gamma}-Al{sub 2}O{sub 3}, amorphous or crystallized SiO{sub 2}, Nb{sub 2}O{sub 5}, CeO{sub 2} and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N{sub 2}, FTIR and FTIR-Pyridine, TEM, STEM, EDS, H{sub 2}-TPR, H{sub 2}-adsorption, H{sub 2}-TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO{sub 2} or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0.53%/30 bars), probably through the hydrogen spillover effect. (author)

  6. Effect of thermal history on the structure of chemically and vapor deposited silver films on glass

    International Nuclear Information System (INIS)

    Shelby, J.E.; Nichols, M.C.; Smith, D.K. Jr.; Vitko, J. Jr.

    1981-01-01

    The observation of silver agglomeration in second surface mirrors used for solar applications has emphasized consideration of the effect of thermal history on the optical properties of mirrors. Thermal history effects may arise from the processing of mirrors, the application of protective coatings, or from outdoor exposure. Mirrors may be subject to elevated temperatures (T less than or equal to 400 0 C) for short periods of time, or to low temperatures (T less than or equal to 60 0 C) for long (less than or equal to 30 years) periods of time. Although a significant amount of work has been done on thermally driven agglomeration of silver films, most of these studies have been restricted to vapor deposited films on vitreous silica. Large area reflectors, such as those used in heliostats, will almost certainly be deposited by commercial chemical methods on substrates of soda-lime-silicate or other glasses which differ considerably from vitreous silica in composition and properties. The present study addresses the effect of this change in deposition technique and substrate on silver agglomeration. These problems were studied by optical and scanning electron microscopy, reflectometry, and x-ray diffraction. The results indicate that both the method used to deposit the silver and the type of glass affect the agglomeration process and the character of the reflective film

  7. Fabrication and electromagnetic interference shielding effectiveness of polymeric composites filled with silver-coated microorganism cells

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Mingming, E-mail: lan_mingming@163.com [College of Mechanical and Electrical Engineering, Henan Agricultural University, Zhengzhou 450002 (China); Zhang, Deyuan; Cai, Jun; Hu, Yanyan; Yuan, Liming [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2014-07-01

    In this paper, helical silver-coated Spirulina cells were used as conductive fillers for the fabrication of polymeric composites. The morphology and composition of the coated Spirulina cells were analyzed with scanning electron microscope and energy dispersive X-ray spectrometer. The densities of silver-coated Spirulina cells were measured using the standard Archimedes method with distilled water. The electrical resistivity was measured by four-probe technique using ammeter and voltmeter whereas electromagnetic interference shielding effectiveness was measured by four-port method using vector network analyzer and coaxial-airline sample holder. The results showed that the silver-coated Spirulina cells with different coating thickness were lightweight fillers compared to the other typical conductive particles. The polymeric composites could achieve good conductivity at the lower content of silver-coated Spirulina cells owing to their helical shape. The shielding effectiveness of polymeric composites had a strong dependence on their conductivity. At the coating thickness of 0.96 μm and the content of 40 vol%, the shielding effectiveness could reach above 74.3 dB in entire test wave band.

  8. 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.

  9. 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

  10. An open, parallel, randomized, comparative, multicenter study to evaluate the cost-effectiveness, performance, tolerance, and safety of a silver-containing soft silicone foam dressing (intervention) vs silver sulfadiazine cream.

    Science.gov (United States)

    Silverstein, Paul; Heimbach, David; Meites, Herbert; Latenser, Barbara; Mozingo, David; Mullins, Fred; Garner, Warren; Turkowski, Joseph; Shupp, Jeffrey; Glat, Paul; Purdue, Gary

    2011-01-01

    An open, parallel, randomized, comparative, multicenter study was implemented to evaluate the cost-effectiveness, performance, tolerance, and safety of a silver-containing soft silicone foam dressing (Mepilex Ag) vs silver sulfadiazine cream (control) in the treatment of partial-thickness thermal burns. Individuals aged 5 years and older with partial-thickness thermal burns (2.5-20% BSA) were randomized into two groups and treated with the trial products for 21 days or until healed, whichever occurred first. Data were obtained and analyzed on cost (direct and indirect), healing rates, pain, comfort, ease of product use, and adverse events. A total of 101 subjects were recruited. There were no significant differences in burn area profiles within the groups. The cost of dressing-related analgesia was lower in the intervention group (P = .03) as was the cost of background analgesia (P = .07). The mean total cost of treatment was $309 vs $513 in the control (P < .001). The average cost-effectiveness per treatment regime was $381 lower in the intervention product, producing an incremental cost-effectiveness ratio of $1688 in favor of the soft silicone foam dressing. Mean healing rates were 71.7 vs 60.8% at final visit, and the number of dressing changes were 2.2 vs 12.4 in the treatment and control groups, respectively. Subjects reported significantly less pain at application (P = .02) and during wear (P = .048) of the Mepilex Ag dressing in the acute stages of wound healing. Clinicians reported the intervention dressing was significantly easier to use (P = .03) and flexible (P = .04). Both treatments were well tolerated; however, the total incidence of adverse events was higher in the control group. The silver-containing soft silicone foam dressing was as effective in the treatment of patients as the standard care (silver sulfadiazine). In addition, the group of patients treated with the soft silicone foam dressing demonstrated decreased pain and lower costs associated

  11. The effect of functionalized silver nanoparticles over the thermal conductivity of base fluids

    Science.gov (United States)

    Seyhan, Merve; Altan, Cem Levent; Gurten, Berna; Bucak, Seyda

    2017-04-01

    Thermal conductivities of nanofluids are expected to be higher than common heat transfer fluids. The use of metal nanoparticles has not been intensely investigated for heat transfer applications due to lack of stability. Here we present an experimental study on the effect of silver nanoparticles (Ag NPs) which are stabilized with surfactants, on the thermal conductivity of water, ethylene glycol and hexane. Hydrophilic Ag NPs were synthesized in aqueous medium with using gum arabic as surfactant and oleic acid/oleylamine were used to stabilize Ag NPs in the organic phase. The enhancement up to 10 per cent in effective thermal conductivity of hexane and ethylene glycol was achieved with addition of Ag NPs at considerably low concentrations (i.e. 2 and 1 per cent, by weight, for hexane and ethylene glycol respectively). However, almost 10 per cent of deterioration was recorded at effective thermal conductivity of water when Ag NPs were added at 1 per cent (by wt). Considerable amount of Gum Arabic in the medium is shown to be the major contributor to this fall, causing lowering of thermal conductivity of water. Same particles performed much better in ethylene glycol where the stabilizer does not lower the thermal conductivity of the base fluid. Also thermal conductivity of nanofluids was found to be temperature independent except water based Ag nanofluids above a threshold concentration. This temperature dependency is suggested to be due to inhibition of hydrogen bonding among water molecules in the presence of high amounts of gum arabic.

  12. Effect of Eugenol against Streptococcus agalactiae and Synergistic Interaction with Biologically Produced Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Renata Perugini Biasi-Garbin

    2015-01-01

    Full Text Available Streptococcus agalactiae (group B streptococci (GBS is an important infections agent in newborns associated with maternal vaginal colonization. Intrapartum antibiotic prophylaxis in GBS-colonized pregnant women has led to a significant reduction in the incidence of early neonatal infection in various geographic regions. However, this strategy may lead to resistance selecting among GBS, indicating the need for new alternatives to prevent bacterial transmission and even to treat GBS infections. This study reported for the first time the effect of eugenol on GBS isolated from colonized women, alone and in combination with silver nanoparticles produced by Fusarium oxysporum (AgNPbio. Eugenol showed a bactericidal effect against planktonic cells of all GBS strains, and this effect appeared to be time-dependent as judged by the time-kill curves and viability analysis. Combination of eugenol with AgNPbio resulted in a strong synergistic activity, significantly reducing the minimum inhibitory concentration values of both compounds. Scanning and transmission electron microscopy revealed fragmented cells and changes in bacterial morphology after incubation with eugenol. In addition, eugenol inhibited the viability of sessile cells during biofilm formation and in mature biofilms. These results indicate the potential of eugenol as an alternative for controlling GBS infections.

  13. Cooperative effect of silver in copper-catalyzed trifluoromethylation of aryl iodides using Me3SiCF3

    KAUST Repository

    Weng, Zhiqiang

    2011-06-13

    An effective model of cooperative effect of silver for the coppercatalyzed trifluoromethylation of activated and unactivated aryl iodides to trifluoromethylated arenes using Me3SiCF3 was achieved with a broad substrate scope. © 2011 American Chemical Society.

  14. Filtration behavior of silver nanoparticle agglomerates and effects of the agglomerate model in data analysis

    International Nuclear Information System (INIS)

    Buha, Jelena; Fissan, Heinz; Wang, Jing

    2013-01-01

    In many data evaluation procedures for particle measuring devices and in filtration models, spherical particles are assumed. However, significant fractions of aerosol particles are agglomerates of small primary spheres. The morphology of particles in filtration processes may not be known a priori and if the filtration data are processed with wrong assumption, errors can be induced. In this work, we have quantified such errors for the case of open-structured agglomerates. Filtration efficiency tests with polydisperse silver nanoparticle agglomerates and their sintered spheres were performed. After the sintering process, particles with a compact structure with the shape close to a sphere are obtained, which are referred to as sintered spheres in the present study. The testing method involved generation of particulate forms, passing the particles through the testing section, and measurement of the particle number concentrations and size distributions before and after the filter. Measurements of the aerosols upstream and downstream of the filter were conducted using scanning mobility particle sizers (SMPS, TSI Inc.), which covered the rage from 10 to 480 nm. Particles were additionally characterized from the electron microscopic images and the average primary particle size was determined to be 16.8 nm. The number-size distribution curves were obtained and used for penetration calculation. The penetration was dependent on the particle size and morphology. Silver-sintered spheres were captured with a lower efficiency than agglomerates with the same mobility diameter because of the stronger interception effect for agglomerates. Data analysis of the number-size distribution for agglomerates was processed based on sphere assumption and using the model for open-structured agglomerates developed by Lall and Friedlander. The efficiencies based on total concentrations of number, surface and volume were affected when the agglomerate model was used. The effect was weakest for the

  15. Effect of laser energy on the SPR and size of silver nanoparticles synthesized by pulsed laser ablation in distilled water

    Science.gov (United States)

    Baruah, Prahlad K.; Sharma, Ashwini K.; Khare, Alika

    2018-04-01

    The effect of incident laser energy on the surface plasmon resonance (SPR) and size of silver nanoparticles synthesized via pulsed laser ablation of silver immersed in distilled water is reported in this paper. The broadening in the plasmonic bandwidth of the synthesized nanoparticles with the increase in the laser energy incident onto the silver target indicates the reduction in size of the nanoparticles. This is confirmed by the transmission electron microscope (TEM) images which show a decrease in the average particle size of the nanoparticles from approximately 15 to 10 nm with the increase in incident laser energy from 30 to 70 mJ, respectively. The structural features as revealed by the selected area electron diffraction and ultra-high resolution TEM studies confirmed the formation of both silver as well as silver oxide nanoparticles.

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  17. The effect of laser ablation parameters on optical limiting properties of silver nanoparticles

    Science.gov (United States)

    Gursoy, Irmak; Yaglioglu, Halime Gul

    2017-09-01

    This paper presents the effect of laser ablation parameters on optical limiting properties of silver nanoparticles. The current applications of lasers such as range finding, guidance, detection, illumination and designation have increased the potential of damaging optical imaging systems or eyes temporary or permanently. The applications of lasers introduce risks for sensors or eyes, when laser power is higher than damage threshold of the detection system. There are some ways to protect these systems such as neutral density (nd) filters, shutters, etc. However, these limiters reduce the total amount of light that gets into the system. Also, response time of these limiters may not be fast enough to prevent damage and cause precipitation in performance due to deprivation of transmission or contrast. Therefore, optical limiting filters are needed that is transparent for low laser intensities and limit or block the high laser intensities. Metal nanoparticles are good candidates for such optical limiting filters for ns pulsed lasers or CW lasers due to their high damage thresholds. In this study we investigated the optical limiting performances of silver nanoparticles produced by laser ablation technique. A high purity silver target immersed in pure water was ablated with a Nd:YAG nanosecond laser at 532 nm. The effect of altering laser power and ablation time on laser ablation efficiency of nanoparticles was investigated experimentally and optimum values were specified. Open aperture Zscan experiment was used to investigate the effect of laser ablation parameters on the optical limiting performances of silver nanoparticles in pure water. It was found that longer ablation time decreases the optical limiting threshold. These results are useful for silver nanoparticles solutions to obtain high performance optical limiters.

  18. Progressive effects of silver nanoparticles on hormonal regulation of reproduction in male rats

    International Nuclear Information System (INIS)

    Dziendzikowska, K.; Krawczyńska, A.; Oczkowski, M.; Królikowski, T.; Brzóska, K.; Lankoff, A.; Dziendzikowski, M.; Stępkowski, T.; Kruszewski, M.

    2016-01-01

    The growing use of silver nanoparticles (AgNPs) in various applications, including consumer, agriculture and medicine products, has raised many concerns about the potential risks of nanoparticles (NPs) to human health and the environment. An increasing body of evidence suggests that AgNPs may have adverse effects of humans, thus the aim of this study was to investigate the effects of AgNPs on the male reproductive system. Silver particles (20 nm AgNPs (groups Ag I and Ag II) and 200 nm Ag sub-micron particles (SPs) (group Ag III)) were administered intravenously to male Wistar rats at a dose of 5 (groups Ag I and Ag III) or 10 (group Ag II) mg/kg of body weight. The biological material was sampled 24 h, 7 days and 28 days after injection. The obtained results revealed that the AgNPs had altered the luteinising hormone concentration in the plasma and the sex hormone concentration in the plasma and testes. Plasma and intratesticular levels of testosterone and dihydrotestosterone were significantly decreased both 7 and 28 days after treatment. No change in the prolactin and sex hormone-binding globulin concentration was observed. Exposure of the animals to AgNPs resulted in a considerable decrease in 5α-reductase type 1 and the aromatase protein level in the testis. Additionally, expression analysis of genes involved in steroidogenesis and the steroids metabolism revealed significant down-regulation of Star, Cyp11a1, Hsd3b1, Hsd17b3 and Srd5a1 mRNAs in AgNPs/AgSPs-exposed animals. The present study demonstrates the potential adverse effect on the hormonal regulation of the male reproductive function following AgNP/AgSP administration, in particular alterations of the sex steroid balance and expression of genes involved in steroidogenesis and the steroids metabolism. - Highlights: • Assessment of the toxic effects of AgNPs/AgSPs on the regulation of male reproductive function • AgNP −/AgSP-induced alterations of sex steroid status in male Wistar rats.

  19. Progressive effects of silver nanoparticles on hormonal regulation of reproduction in male rats

    Energy Technology Data Exchange (ETDEWEB)

    Dziendzikowska, K., E-mail: k.dziendzikowska@gmail.com [Division of Nutrition Physiology, Department of Dietetics, Faculty of Human Nutrition and Consumer Science, Warsaw University of Life Sciences – SGGW, Nowoursynowska 159C, 02-776 Warsaw (Poland); Krawczyńska, A. [Laboratory of Molecular Biology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna (Poland); Oczkowski, M.; Królikowski, T. [Division of Nutrition Physiology, Department of Dietetics, Faculty of Human Nutrition and Consumer Science, Warsaw University of Life Sciences – SGGW, Nowoursynowska 159C, 02-776 Warsaw (Poland); Brzóska, K. [Centre for Radiobiology and Biological Dosimetry, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland); Lankoff, A. [Centre for Radiobiology and Biological Dosimetry, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland); Department of Radiobiology and Immunology, Institute of Biology, Jan Kochanowski University, Świetokrzyska 15, 25-406 Kielce (Poland); Dziendzikowski, M. [Airworthiness Division, Air Force Institute of Technology, Ks. Boleslawa 6, 01-494 Warsaw (Poland); Stępkowski, T. [Centre for Radiobiology and Biological Dosimetry, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw (Poland); Kruszewski, M. [Department of Medical Biology and Translational Research, Faculty of Medicine, University of Information Technology and Management, Sucharskiego 2, 35-225 Rzeszów (Poland); Department of Molecular Biology and Translational Research, Institute of Rural Health, Jaczewskiego 2, 20-090 Lublin (Poland); and others

    2016-12-15

    The growing use of silver nanoparticles (AgNPs) in various applications, including consumer, agriculture and medicine products, has raised many concerns about the potential risks of nanoparticles (NPs) to human health and the environment. An increasing body of evidence suggests that AgNPs may have adverse effects of humans, thus the aim of this study was to investigate the effects of AgNPs on the male reproductive system. Silver particles (20 nm AgNPs (groups Ag I and Ag II) and 200 nm Ag sub-micron particles (SPs) (group Ag III)) were administered intravenously to male Wistar rats at a dose of 5 (groups Ag I and Ag III) or 10 (group Ag II) mg/kg of body weight. The biological material was sampled 24 h, 7 days and 28 days after injection. The obtained results revealed that the AgNPs had altered the luteinising hormone concentration in the plasma and the sex hormone concentration in the plasma and testes. Plasma and intratesticular levels of testosterone and dihydrotestosterone were significantly decreased both 7 and 28 days after treatment. No change in the prolactin and sex hormone-binding globulin concentration was observed. Exposure of the animals to AgNPs resulted in a considerable decrease in 5α-reductase type 1 and the aromatase protein level in the testis. Additionally, expression analysis of genes involved in steroidogenesis and the steroids metabolism revealed significant down-regulation of Star, Cyp11a1, Hsd3b1, Hsd17b3 and Srd5a1 mRNAs in AgNPs/AgSPs-exposed animals. The present study demonstrates the potential adverse effect on the hormonal regulation of the male reproductive function following AgNP/AgSP administration, in particular alterations of the sex steroid balance and expression of genes involved in steroidogenesis and the steroids metabolism. - Highlights: • Assessment of the toxic effects of AgNPs/AgSPs on the regulation of male reproductive function • AgNP −/AgSP-induced alterations of sex steroid status in male Wistar rats.

  20. Effect of pressure on ionic conductivity in rubidium silver iodide and silver iodide

    International Nuclear Information System (INIS)

    Allen, P.C.; Lazarus, D.

    1978-01-01

    The effect of pressure on the ionic conductivity of RbAg 4 I 5 and AgI has been measured, using single crystals and polycrystalline samples, up to pressures of 6 kbar. The activation volumes for motion in α-RbAg 4 I 5 and β-RbAg 4 I 5 , respectively, are -0.4 +- 0.2 and -0.2 +- 0.1 cm 3 /mole. In α-AgI, the motion volume increases from 0.56 +- 0.1 cm 3 /mole at 435 K to 0.8 +- 0.1 cm 3 /mole at 623 K. These values are unusually small in relation to the activation energies and are not consistent with the strain-energy model or a domain-diffusion mechanism. The logarithms of the ionic conductivities of α- and β-RbAg 4 I 5 increase linearly at first and then decrease quadratically with pressure. This is related to the large quadratic pressure dependence of the second-order transition temperature ΔT/sub c/(K) = 0.141P(kbar) + 0.111P 2 (kbar 2 ). The variation of the 122-K transition temperature with pressure is ΔT/sub c/(K) = 5.65P(kbar)-0.53P 2 (kbar 2 ), implying a molar volume change of V/sub β/γ = 0.37 +- 0.01 cm 3 /mole and a change in compressibility K/sub β/γ = (0.033 +- 0.001) x 10 -11 cm 2 /dyn across the transition. The ionic conductivity of γ-RbAg 4 I 5 initially decreases with an activation volume of 9 +- 1 cm 3 /mole, and then levels off with increasing pressure. The negative activation volume for conduction along the c axis in β-AgI has been confirmed. Both low-temperature phases have large formation volumes consistent with the theory of Rice et al. of transitions to the superionic phase

  1. Effect of Poloxamer on Zingiber Officinale Extracted Green Synthesis and Antibacterial Studies of Silver Nanoparticles.

    Science.gov (United States)

    Chitra, K; Manikandan, A; Antony, S Arul

    2016-01-01

    The Zingiber officinale (Z. officinale) plant is one of the well-known medicinal plants. Poloxamer finds excellent clinical and therapeutic uses for curing of various ailments. The poloxamer 188 polymer and the plant extract of Z. officinale have been used to prepare the silver nanoparticles (AgNPs) by a green synthesis route. The Z. officinale plant extract has been used as a reducing agent, while the poloxamer 188 has been used as a stabilizing agent. The formation of face-centered cubic (fcc) structure AgNPs was confirmed by X-ray diffraction pattern. The effect of addition of poloxamer on the controlling the shape, size and morphologies of the AgNPs has been investigated by transmission electron microscopy (TEM) and dynamic light scattering techniques. The elemental composition of AgNPs was confirmed by energy dispersive X-ray (EDX) analysis. The anti-bacterial activity of AgNPs has been investigated using three human pathogens Escherichia coli, Klebsiella pneumonia and Staphylococcus aureus. The poloxamer 188 protected AgNPs inhibit the bacterial growth more effectively than the pure Z. officinale extract and the Z. officinale extract AgNPs.

  2. Evaluation of Antibacterial Effects of Silver-Coated Stainless Steel Orthodontic Brackets.

    Science.gov (United States)

    Arash, Valiollah; Keikhaee, Fatemeh; Rabiee, Sayed Mahmood; Rajabnia, Ramazan; Khafri, Soraya; Tavanafar, Saeid

    2016-01-01

    White spots and enamel demineralization around orthodontic brackets are among the most important complications resulting from orthodontic treatments. Since the antibacterial properties of metals and metallic particles have been well documented, the aim of this study was to assess the antibacterial effect of stainless steel orthodontic brackets coated with silver (Ag) particles. In this study, 40 standard metal brackets were divided into two groups of 20 cases and 20 controls. The brackets in the case group were coated with Ag particles using an electroplating method. Atomic force microscopy and scanning electron microscopy were used to assess the adequacy of the coating process. In addition, antibacterial tests, i.e., disk diffusion and direct contact tests were performed at three, six, 24, and 48 hours, and 15 and 30 days using a Streptococcus mutans strain. The results were analyzed using Student's t-test and repeated measures ANOVA. Analyses via SEM and AFM confirmed that excellent coatings were obtained by using an electroplating method. The groups exhibited similar behavior when subjected to the disk diffusion test in the agar medium. However, the bacterial counts of the Ag-coated brackets were, in general, significantly lower (PBrackets coated with Ag, via an electroplating method, exhibited antibacterial properties when placed in direct contact with Streptococcus mutans. This antibacterial effect persisted for 30 days after contact with the bacteria.

  3. Rapid green synthesis of silver nanoparticles from Chrysanthemum indicum L and its antibacterial and cytotoxic effects: an in vitro study

    Directory of Open Access Journals (Sweden)

    Arokiyaraj S

    2014-01-01

    Full Text Available Selvaraj Arokiyaraj,1 Mariadhas Valan Arasu,2 Savariar Vincent,3 Nyayirukannaian Udaya Prakash,4 Seong Ho Choi,5 Young-Kyoon Oh,1 Ki Choon Choi,2 Kyoung Hoon Kim1,61Department of Animal Nutrition and Physiology, National Institute of Animal Science, Rural Development Administration, Suwon, Republic of Korea; 2Grassland and Forage Division, National Institute of Animal Science, Rural Development Administration, Seonghwan-Eup, Cheonan-Si, Chungnam, Republic of Korea; 3Center for Environmental Research and Development, Loyola College, Chennai, India; 4Research and Development, Vel Tech Dr RR and Dr SR Technical University, Chennai, India; 5Department of Animal Science, Chungbuk National University, Chungbuk, Republic of Korea; 6Department of Animal Science, Seoul National University, Pyeongchang, Republic of KoreaAbstract: The present work reports a simple, cost-effective, and ecofriendly method for the synthesis of silver nanoparticles (AgNPs using Chrysanthemum indicum and its antibacterial and cytotoxic effects. The formation of AgNPs was confirmed by color change, and it was further characterized by ultraviolet–visible spectroscopy (435 nm. The phytochemical screening of C. indicum revealed the presence of flavonoids, terpenoids, and glycosides, suggesting that these compounds act as reducing and stabilizing agents. The crystalline nature of the synthesized particles was confirmed by X-ray diffraction, as they exhibited face-centered cubic symmetry. The size and morphology of the particles were characterized by transmission electron microscopy, which showed spherical shapes and sizes that ranged between 37.71–71.99 nm. Energy-dispersive X-ray spectroscopy documented the presence of silver. The antimicrobial effect of the synthesized AgNPs revealed a significant effect against the bacteria Klebsiella pneumonia, Escherichia coli, and Pseudomonas aeruginosa. Additionally, cytotoxic assays showed no toxicity of AgNPs toward 3T3 mouse embryo

  4. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-21

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

  6. Effect of kaolin silver complex on the control of populations of Brettanomyces and acetic acid bacteria in wine.

    Science.gov (United States)

    Izquierdo-Cañas, P M; López-Martín, R; García-Romero, E; González-Arenzana, L; Mínguez-Sanz, S; Chatonnet, P; Palacios-García, A; Puig-Pujol, A

    2018-05-01

    In this work, the effects of kaolin silver complex (KAgC) have been evaluated to replace the use of SO 2 for the control of spoilage microorganisms in the winemaking process. The results showed that KAgC at a dose of 1 g/L provided effective control against the development of B. bruxellensis and acetic acid bacteria. In wines artificially contaminated with an initial population of B. bruxellensis at 10 4 CFU/mL, a concentration proven to produce off flavors in wine, only residual populations of the contaminating yeast remained after 24 days of contact with the additive. Populations of acetic bacteria inoculated into wine at concentrations of 10 2 and 10 4  CFU/mL were reduced to negligible levels after 72 h of treatment with KAgC. The antimicrobial effect of KAgC against B. bruxellensis and acetic bacteria was also demonstrated in a wine naturally contaminated by these microorganisms, decreasing their population in a similar way to a chitosan treatment. Related to this effect, wines with KAgC showed lower concentrations of acetic acid and 4-ethyl phenol than wines without KAgC. The silver concentration from KAgC that remained in the finished wines was below the legal limits. These results demonstrated the effectiveness of KAgC to reduce spoilage microorganisms in winemaking.

  7. Effects of high-dose hydrogen implantation on defect formation and dopant diffusion in silver implanted ZnO crystals

    Energy Technology Data Exchange (ETDEWEB)

    Yaqoob, Faisal [Department of Physics, State University of New York at Albany, Albany, New York 12222 (United States); Huang, Mengbing, E-mail: mhuang@sunypoly.edu [College of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, Albany, New York 12203 (United States)

    2016-07-28

    This work reports on the effects of a deep high-dose hydrogen ion implant on damage accumulation, defect retention, and silver diffusion in silver implanted ZnO crystals. Single-crystal ZnO samples were implanted with Ag ions in a region ∼150 nm within the surface, and some of these samples were additionally implanted with hydrogen ions to a dose of 2 × 10{sup 16 }cm{sup −2}, close to the depth ∼250 nm. Rutherford backscattering/ion channeling measurements show that crystal damage caused by Ag ion implantation and the amount of defects retained in the near surface region following post-implantation annealing were found to diminish in the case with the H implantation. On the other hand, the additional H ion implantation resulted in a reduction of substitutional Ag atoms upon post-implantation annealing. Furthermore, the presence of H also modified the diffusion properties of Ag atoms in ZnO. We discuss these findings in the context of the effects of nano-cavities on formation and annihilation of point defects as well as on impurity diffusion and trapping in ZnO crystals.

  8. Silver colloidal effects on excited-state structure and intramolecular charge transfer of p-N, N-dimethylaminobenzoic acid in aqueous cyclodextrin solutions

    International Nuclear Information System (INIS)

    Choi, Jung Kwon; Kim, Yang Hee; Yoon, Min Joong; Lee, Seung Joon; Kim, Kwan; Jeoung, Sae Chae

    2001-01-01

    The silver colloidal effects on the excited-state structure and intramolecular charge transfer (ICT) of p-N,N-dimethylaminobenzoic acid (DMABA) in aqueous cyclodextrin (CD) solutions have been investigated by UV-VIS absorption, steady-state and time-resolved fluorescence, and transient Raman spectroscopy. As the concentration of silver colloids increases, the ratio of the ICT emission to the normal emission (I a /I b ) of DMABA in the aqueous α-CD solutions are greatly decreased while the I a /I b values in the aqueous β-CD solutions are significantly enhanced. It is also noteworthy that the ICT emission maxima are red-shifted by 15-40 nm upon addition of silver colloids, implying that DMABA encapsulated in α-CD or β-CD cavity is exposed to more polar environment. The transient resonance Raman spectra of DMABA in silver colloidal solutions demonstrate that DMABA in the excited-state is desorbed from silver colloidal surfaces as demonstrated by the disappearance of v s (CO 2 - )(1380 cm -1 ) with appearance of v (C-OH)(1280 cm -1 ) band, respectively. Thus, in the aqueous β-CD solutions the carboxylic acid group of DMABA in the excited-state can be readily hydrogen bonded with the secondary hydroxyl group of β-CD while in aqueous and α-CD solutions the carboxylic acid group of DMABA has the hydrogen-bonding interaction with water. Consequently, in the aqueous β-CD solutions the enhancement of the I a /I b value arises from the intermolecular hydrogen-bonding interaction between DMABA and the secondary hydroxyl group of β-CD as well as the lower polarity of the rim of the β-CD cavity compared to bulk water. This is also supported by the increase of the association constant for DMABA/β-CD complex in the presence of silver colloids

  9. Effect of iodine impurity on relaxation of photoexcited silver chloride

    International Nuclear Information System (INIS)

    Vostrikova, Yu. V.; Klyuev, V. G.

    2008-01-01

    The time and temperature dependences of relaxation of excited AgCl and AgCl:I crystals is studied by the method of photostimulated flash of luminescence. The presence of iodine impurity in silver chloride gives rise to hole recombination (luminescence) centers and hole traps in the band gap. It is shown that the main contribution to the decrease in the concentration of electrons localized at deep traps is made by the recombination of electrons with holes released thermally from shallow localization levels (iodine-related centers). Estimation of activation energy for the relaxation process showed that these energies for the AgCl and AgCl:I samples under study are the same within the experimental error and are equal to E rel1 = 0.01 ± 0.0005 eV for the initial stage of relaxation and E rel2 = 0.09 ± 0.005 eV for the final state. This fact indicates that the majority of hole traps involved in the relaxation process in AgCl are related to iodine impurity. In the course of thermal relaxation in AgCl, relocalization of nonequilibrium charge carriers from shallow levels to deep levels is observed. The depth of the corresponding trap is E arl = 0.174 ± 0.03 eV.

  10. Cost-effective use of silver dressings for the treatment of hard-to-heal chronic venous leg ulcers

    DEFF Research Database (Denmark)

    Jemec, Gregor B E; Kerihuel, Jean Charles; Ousey, Karen

    2014-01-01

    AIM: To estimate the cost-effectiveness of silver dressings using a health economic model based on time-to-wound-healing in hard-to-heal chronic venous leg ulcers (VLUs). BACKGROUND: Chronic venous ulceration affects 1-3% of the adult population and typically has a protracted course of healing....... METHODS: A decision tree was constructed to evaluate the cost-effectiveness of treatment with silver compared with non-silver dressings for four weeks in a primary care setting. The outcomes: 'Healed ulcer', 'Healing ulcer' or 'No improvement' were developed, reflecting the relative reduction in ulcer...

  11. Bioavailability of silver and silver sulfide nanoparticles to lettuce (Lactuca sativa): Effect of agricultural amendments on plant uptake.

    Science.gov (United States)

    Doolette, Casey L; McLaughlin, Michael J; Kirby, Jason K; Navarro, Divina A

    2015-12-30

    Silver nanoparticles (AgNPs) can enter terrestrial systems as sulfidised AgNPs (Ag2S-NPs) through the application of biosolids to soil. However, the bioavailability of Ag2S-NPs in soils is unknown. The two aims of this study were to investigate (1) the bioavailability of Ag to lettuce (Lactuca sativa) using a soil amended with biosolids containing Ag2S-NPs and (2) the effect of commonly used agricultural fertilisers/amendments on the bioavailability of Ag, AgNPs and Ag2S-NPs to lettuce. The study used realistic AgNP exposure pathways and exposure concentrations. The plant uptake of Ag from biosolids-amended soil containing Ag2S-NPs was very low for all Ag treatments (0.02%). Ammonium thiosulfate and potassium chloride fertilisation significantly increased the Ag concentrations of plant roots and shoots. The extent of the effect varied depending on the type of Ag. Ag2S-NPs, the realistic form of AgNPs in soil, had the lowest bioavailability. The potential risk of AgNPs in soils is low; even in the plants that had the highest Ag concentrations (Ag(+)+thiosulfate), only 0.06% of added Ag was found in edible plant parts (shoots). Results from the study suggest that agricultural practises must be considered when carrying out risk assessments of AgNPs in terrestrial systems; such practises can affect AgNP bioavailability. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Enhanced antibacterial activity of silver-decorated sandwich-like mesoporous silica/reduced graphene oxide nanosheets through photothermal effect

    Science.gov (United States)

    Liu, Rong; Wang, Xuandong; Ye, Jun; Xue, Ximei; Zhang, Fangrong; Zhang, Huicong; Hou, Xuemei; Liu, Xiaolong; Zhang, Yun

    2018-03-01

    Drug resistance of bacteria has become a global health problem, as it makes conventional antibiotics less efficient. It is urgently needed to explore novel antibacterial materials and develop effective treatment strategies to overcome the drug resistance of antibiotics. Herein, we successfully synthesized silver decorated sandwich-like mesoporous silica/reduced graphene oxide nanosheets (rGO/MSN/Ag) as a novel antibacterial material through facile method. The rGO and Ag nanoparticles can be reduced in the reaction system without adding any other reductants. In addition, the rGO/MSN/Ag showed higher photothermal conversion capacity due to the modification of silver nanoparticles and exhibited excellent antibacterial activities against Pseudomonas putida, Escherichia coli and Rhodococcus at relatively low dosages, which was confirmed by the minimum inhibitory concentration (MIC) test. Meanwhile, the E. coli with a high concentration was selected for exposure using an 808 nm laser, and the antibacterial effect was obviously enhanced by the near-infrared irradiation induced photothermal effect. Moreover, the hepatocyte LO2 were used for the cytotoxicity evaluation, and the rGO/MSN/Ag showed low toxicity and were without detectable cytotoxicity at the antimicrobial dose. As the prepared rGO/MSN/Ag nanosheets have the advantages of low-cost and high antibacterial activity, they might be of promising and useful antibacterial agents for different applications.

  13. 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.

  14. Investigating the effect of silver coating on the solubility, antibacterial properties, and cytocompatibility of glass microspheres.

    Science.gov (United States)

    Haas, L M; Smith, C M; Placek, L M; Hall, M M; Gong, Y; Mellott, N P; Wren, Anthony W

    2015-10-01

    Silver (Ag) coatings have been incorporated into many medical materials due to its ability to eradicate harmful microbes. In this study, glass microspheres (SiO2-Na2O-CaO-Al2O3) were synthesized and employed as substrates to investigate the effect Ag coating has on glass solubility and the subsequent biological effects. Initially, glasses were amorphous with a glass transition point (T(g)) of 605℃ and microspheres were spherical with a mean particle diameter of 120 µm (±27). The Ag coating was determined to be crystalline in nature and its presence was confirmed using scanning electron microscopy and X-ray photoelectron spectroscopy. Ion release determined that Ag-coated (Ag-S) microspheres increased the Na(+) release rate but slightly reduced the Ca(2+) and Si(4+) release compared to an uncoated control (UC-S). Additionally, the Ag-S reduced the pH to just above neutral (7.3-8.5) compared to the UC-S (7.7-9.1). Antibacterial testing determined significant reductions in planktonic Escherichia coli (p = 0.000), Staphylococcus epidermidis (p = 0.000) and Staphylococcus aureus (p = 0.000) growth as a function of the presence of Ag and with respect to maturation (1, 7, and 30 days). Testing for toxicity levels using L929 Fibroblasts determined higher cell viability for the Ag-S at lower concentrations (5 µg/ml); in addition, no significant reduction in cell viability was observed with higher concentrations (15, 30 µg/ml). © The Author(s) 2015.

  15. The Effect of Glancing Angle Deposition Conditions on the Morphology of a Silver Nanohelix Array

    Directory of Open Access Journals (Sweden)

    Yi-Jun Jen

    2017-09-01

    Full Text Available Silver nanohelices were grown on smooth substrates using glancing angle deposition and substrate cooling. Various nanohelix arrays were deposited under different deposition conditions—different deposition rates, substrate spin rates, deposition angles, and substrate temperatures. The effect of deposition conditions on the morphology of each nanohelix array in terms of pitch angle, pitch length, wire diameter, and radius of curvature was investigated. The dependence of circular dichroism on the size of the nanohelix arrays was also measured and demonstrated.

  16. The effect of silver nanoparticle size on Jc of YBa2Cu3O7-x superconductor

    International Nuclear Information System (INIS)

    Farbod, M.; Batvandi, M.; Shoushtari, M. Z.

    2007-01-01

    Full text: Critical current density Jc is one of the most important superconducting parameters which is crucial in superconductor's applications. Introducing silver into the superconductors as intergrain filler has been a routine way to increase the Jc. In this work, YBa 2 Cu 3 O 7-x (YBCO), was doped by silver nanoparticles and their effect was studied on Jc as the flux pinning centers. Silver nanoparticles with sizes ranging from 30 to 1000 nm have been prepared using the reduction of silver in ethanol. The stoichiometric amounts of initial material of YBCO superconductor were added to the solution. After evaporation of ethanol, the obtained powder was used to fabricate YBCO samples. The total weight ratio of silver nanoparticles to superconductor was 1:100. The samples were characterized using SEM, EDX and XRD measurements. Jc was measured by a standard four probe technique. The results show by increasing silver nanoparticle size up to 700 nm, Jc increases then decreases by further increase in silver particle size. (authors)

  17. THE EFFECT OF VOLUME VARIATION OF SILVER NANOPARTICLE SOLUTION TOWARDS THE POROSITY AND COMPRESSIVE STRENGTH OF MORTAR

    Directory of Open Access Journals (Sweden)

    W.S.B. Dwandaru

    2016-10-01

    Full Text Available As the world is growing rapidly, people need better building materials such as mortar. The aim of this research is to determine the effect of adding silver nanoparticle solution towards the porosity and compressive strength of mortar. This research was started by making silver nanoparticle solution from nitrate silver (AgNO3. The solution is then characterized using Uv-Vis spectrophotometer. 5 mM silver nanoparticle is added in the process of mortar production with volume variation of the silver nanoparticle solution. The porosity, compressive strength, and the content of mortar were determined by digital scale, universal testing machine, and X-ray diffraction, respectively. For silver nanoparticle solution volumes of (in mL 0, 5, 10, 15, 20, and 25 the porosity obtained are (in % 20.38, 19.48, 19.42, 18.9, 17.8, and 17.5, respectively. The best increase in compressive strength is obtained for (in MPa 29,068, 29,308, and 31,385, with nanoparticle solution volumes of (in mL 5, 10, and 15   Keywords: mortar, silver nanoparticle, compressive strength

  18. Bacteria and virus removal effectiveness of ceramic pot filters with different silver applications in a long term experiment.

    Science.gov (United States)

    van der Laan, H; van Halem, D; Smeets, P W M H; Soppe, A I A; Kroesbergen, J; Wubbels, G; Nederstigt, J; Gensburger, I; Heijman, S G J

    2014-03-15

    In 2012 more than 4 million people used a ceramic pot filter (CPF) as household water treatment system for their daily drinking water needs. In the normal production protocol most low cost filters are impregnated with a silver solution to enhance the microbial removal efficiency. The aim of this study was to determine the role of silver during the filtration and subsequent storage. Twenty-two CPFs with three different silver applications (non, only outside and both sides) were compared in a long-term loading experiment with Escherichia coli (K12 and WR1) and MS2 bacteriophages in natural challenge water under highly controlled laboratory circumstances. No significant difference in Log Removal Values were found between the filters with different silver applications. The results show that the storage time in the receptacle is the dominant parameter to reach E. coli inactivation by silver, and not the contact time during the filtration phase. The hypothesis that the absence of silver would enhance the virus removal, due to biofilm formation on the ceramic filter element, could not be confirmed. The removal effectiveness for viruses is still of major concern for the CPF. This study suggests that the ceramic pot filter characteristics, such as burnt material content, do not determine E. coli removal efficacies, but rather the contact time with silver during storage is the dominant parameter to reach E. coli inactivation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Effects of chlorine and other water quality parameters on the release of silver nanoparticles from a ceramic surface.

    Science.gov (United States)

    Bielefeldt, Angela R; Stewart, Michael W; Mansfield, Elisabeth; Scott Summers, R; Ryan, Joseph N

    2013-08-01

    A quartz crystal microbalance was used to determine the effects of different water quality parameters on the detachment of silver nanoparticles from surfaces representative of ceramic pot filters (CPFs). Silver nanoparticles stabilized with casein were used in the experiments. The average hydrodynamic diameter of the nanoparticles ranged from 20 nm to 100 nm over a pH range of 6.5-10.5. The isoelectric point was about 3.5 and the zeta potential was -45 mV from pH 4.5 to 9.5. The silver nanoparticles were deposited onto silica surfaces and a quartz crystal microbalance was used to monitor silver release from the surface. At environmentally relevant ranges of pH (4.8-9.3), ionic strength (0 and 150 mol/m(3) NaNO3 or 150 mol/m(3) Ca(NO3)2), and turbidity (0 and 51.5 NTU kaolin clay), the rates of silver release were similar. A high concentration of sodium chloride and bacteria (Echerichia coli in 10% tryptic soy broth) caused rapid silver release. Water containing sodium hypochlorite removed 85% of the silver from the silica surface within 3 h. The results suggest that contact between CPFs and prechlorinated water or bleach CPF cleaning should be avoided. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. The effects of silver nanoparticles on mouse embryonic stem cell self-renewal and proliferation

    Directory of Open Access Journals (Sweden)

    Pavan Rajanahalli

    2015-01-01

    Full Text Available Silver nanoparticles (AgNPs are gaining rapid popularity in many commonly used medical and commercial products for their unique anti-bacterial properties. The molecular mechanisms of effects of AgNPs on stem cell self-renewal and proliferation have not yet been well understood. The aim of the work is to use mouse embryonic stem cells (mESCs as a cellular model to evaluate the toxicity of AgNPs. mESC is a very special cell type which has self-renewal and differentiation properties. The objective of this project is to determine the effects of AgNPs with different surface chemical compositions on the self-renewal and cell cycle of mESCs. Two different surface chemical compositions of AgNPs, polysaccharide-coated and hydrocarbon-coated, were used to test their toxic effects on self-renewal and proliferation of mESCs. The results indicated that both polysaccharide-coated and hydrocarbon-coated AgNPs changed the cell morphology of mESCs. Cell cycle analysis indicated that AgNPs induced mESCs cell cycle arrest at G1 and S phases through inhibition of the hyperphosphorylation of Retinoblastoma (Rb protein. Furthermore, AgNPs exposure reduced Oct4A isoform expression which is responsible for the pluripotency of mESCs, and induced the expression of several isoforms OCT4B-265, OCT4B-190, OCT4B-164 which were suggested involved in stem cell stresses responses. In addition, the evidence of reactive oxygen species (ROS production with two different surface chemical compositions of AgNPs supported our hypothesis that the toxic effect AgNPs exposure is due to overproduction of ROS which altered the gene expression and protein modifications. Polysaccharide coating reduced ROS production, and thus reduced the AgNPs toxicity.

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-10-15

    Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly(N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 {mu}g mL{sup -1} induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

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

    Science.gov (United States)

    Mahl, Dirk; Diendorf, Jörg; Ristig, Simon; Greulich, Christina; Li, Zi-An; Farle, Michael; Köller, Manfred; Epple, Matthias

    2012-10-01

    Silver, gold, and silver-gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly( N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15-25 nm), gold (5-6 nm), and silver-gold (50:50; 10-12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver-gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver-gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver-gold nanoparticles in the concentration range of 5-20 μg mL-1 induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

  4. High-Throughput Fabrication Method for Producing a Silver-Nanoparticles-Doped Nanoclay Polymer Composite with Novel Synergistic Antibacterial Effects at the Material Interface.

    Science.gov (United States)

    Cai, Shaobo; Pourdeyhimi, Behnam; Loboa, Elizabeth G

    2017-06-28

    In this study, we report a high-throughput fabrication method at industrial pilot scale to produce a silver-nanoparticles-doped nanoclay-polylactic acid composite with a novel synergistic antibacterial effect. The obtained nanocomposite has a significantly lower affinity for bacterial adhesion, allowing the loading amount of silver nanoparticles to be tremendously reduced while maintaining satisfactory antibacterial efficacy at the material interface. This is a great advantage for many antibacterial applications in which cost is a consideration. Furthermore, unlike previously reported methods that require additional chemical reduction processes to produce the silver-nanoparticles-doped nanoclay, an in situ preparation method was developed in which silver nanoparticles were created simultaneously during the composite fabrication process by thermal reduction. This is the first report to show that altered material surface submicron structures created with the loading of nanoclay enables the creation of a nanocomposite with significantly lower affinity for bacterial adhesion. This study provides a promising scalable approach to produce antibacterial polymeric products with minimal changes to industry standard equipment, fabrication processes, or raw material input cost.

  5. (ajst) additive main effects and multiplicative

    African Journals Online (AJOL)

    2013-08-02

    Aug 2, 2013 ... genotypes assessed by biplot analysis showed that the most stable ... biplot is a useful tool for the analysis of multi-environment trial (MET) data. ... multiplicative components, extracting first the additive ... The AMMI analysis of variance of cassava harvest index of the 8 .... wheat mega-environments in Iran.

  6. The effect of linear imperfection in [001] direction on the thermal properties of silver crystal

    Directory of Open Access Journals (Sweden)

    J Davoodi

    2013-09-01

    Full Text Available  The aim of this investigation was to calculate the thermal properties of silver crystal in the presence of linear imperfection. The simulations were performed by molecular dynamics simulation technique in NPT as well as NVT ensemble based on quantum Sutton-Chen many body potential. The thermal properties including cohesive energy, melting temperature, isobaric heat capacity and thermal expansion of imperfect silver crystal were calculated and compared to those of the perfect crystal. Moreover, the quantities such as radial distribution function, order parameter and lindemann index were calculated in order to obtain information on crystal structure and disorder in atoms. All calculations were done both with liner imperfection in [001] direction and without imperfection at different temperature. The simulation results show that cohesive energy, linear thermal expansion coefficient increase and melting temperature, latent heat of fusion decrease with increasing linear imperfection. Also, the results show that linear imperfection has no effect on the heat capacity.

  7. Effect of non-stationary current regimes on the morphology of silver electrodeposits

    Directory of Open Access Journals (Sweden)

    ALEKSANDAR T. DIMITROV

    2009-03-01

    Full Text Available This work is concerned with the use of reverse current regimes in order to form small-grained and compact silver deposits during the electro-refining process. Several parameters were varied, i.e., i anodic overpotential, ii cathodic vs. anodic time ratio and iii duration of the anodic pulse. After optimization of these parameters, phosphate ions were added and the electrolyte was stirred. The effects of a rise of the anodic overpotential on the grain sizes of the silver deposit and compactness were studied. Prolongation of the anodic time had a similar influence but with a decrease in current efficiency. An increase of the cathodic vs. anodic time ratio caused an enlargement of the grains and a decrease in the compactness of the deposit. Optimal morphological characteristics were obtained when PO43- was added and the electrolyte was stirred.

  8. Acute toxicity, bioaccumulation and effects of dietary transfer of silver from brine shrimp exposed to PVP/PEI-coated silver nanoparticles to zebrafish.

    Science.gov (United States)

    Lacave, José María; Fanjul, Álvaro; Bilbao, Eider; Gutierrez, Nerea; Barrio, Irantzu; Arostegui, Inmaculada; Cajaraville, Miren P; Orbea, Amaia

    2017-09-01

    The extensive use and release to the aquatic environment of silver nanoparticles (NPs) could lead to their incorporation into the food web. Brine shrimp larvae of 24h showed low sensitivity to the exposure to PVP/PEI-coated Ag NPs (5nm), with EC 50 values at 24h of 19.63mgAgL -1 , but they significantly accumulated silver after 24h of exposure to 100μgL -1 of Ag NPs. Thus, to assess bioaccumulation and effects of silver transferred by the diet in zebrafish, brine shrimp larvae were exposed to 100ngL -1 of Ag NPs as an environmentally relevant concentration or to 100μgL -1 as a potentially effective concentration and used to feed zebrafish for 21days. Autometallography revealed a dose- and time-dependent metal accumulation in the intestine and in the liver of zebrafish. Three-day feeding with brine shrimps exposed to 100ngL -1 of Ag NPs was enough to impair fish health as reflected by the significant reduction of lysosomal membrane stability and the presence of vacuolization and necrosis in the liver. However, dietary exposure to 100μgL -1 of Ag NPs for 3days did not significantly alter gene transcription levels, neither in the liver nor in the intestine. After 21days, biological processes such as lipid transport and localization, cellular response to chemical stimulus and response to xenobiotic stimulus were significantly altered in the liver. Overall, these results indicate an effective dietary transfer of silver and point out to liver as the main target organ for Ag NP toxicity in zebrafish after dietary exposure. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit.

    Science.gov (United States)

    Xi, Peng; Li, Yan; Ge, Xiaojin; Liu, Dandan; Miao, Mingsan

    2018-05-01

    Observing the effect of nano-silver hydrogel coating film on deep partial thickness scald model of rabbit. We prepared boiling water scalded rabbits with deep II degree scald models and applied high, medium and low doses of nano-silver hydrogel coating film for different time and area. Then we compared the difference of burned paper weight before administration and after administration model burns, burn local skin irritation points infection, skin crusting and scabs from the time, and the impact of local skin tissue morphology. Rabbits deep II degree burn model successful modeling; on day 12, 18, high, medium and low doses of nano-silver hydrogel coating film significantly reduced skin irritation of rabbits infected with the integral value ( P  film group significantly decreased skin irritation, infection integral value ( P  film significantly reduced film rabbits' scalded skin crusting time ( P  film on the deep partial thickness burns has a significant therapeutic effect; external use has a significant role in wound healing.

  10. Efeito da adição de aminoácidos essenciais à dieta sobre a secreção de enzimas digestivas de jundiá Rhamdia quelen (Siluriformes, Pimelodidae = Effect of dietary essential amino acids addition on digestive enzime secretion in silver catfish Rhamdia quelen (Siluriformes, Pimelodidae

    Directory of Open Access Journals (Sweden)

    Alexandre Bernardini Ungar

    2009-01-01

    Full Text Available Em estudos realizados com variação no teor de proteína na ração para peixes, foi demonstrado o aumento das atividades de protease alcalina, protease ácida, tripsina e quimiotripsina do trato digestório de jundiá (Rhamdia quelen. Esses fatos sugerem que produtos liberados pela digestão na luz desse trato podem influenciar a síntese e a secreção de enzimas digestivas. A secreção destas enzimas pelo pâncreas, em vertebrados, responde à influência neurale humoral. No presente trabalho, foram testadas quatro concentrações (0, 3, 6 e 12% de uma mistura de aminoácidos (treonina, fenilalanina, leucina, valina, arginina e triptofano em iguaisproporções em dietas isocalóricas contendo 3.500 kcal de energia digestível kg-1 de ração, e dietas isoproteicas contendo 20% de proteína, em juvenis de jundiá. Foram utilizados dez animais portratamento, sendo os peixes estocados num sistema fechado com recirculação de água e temperatura controlada. Os peixes submetidos a estes tratamentos apresentaram atividade da protease alcalina na região anterior do intestino, responsiva aos diferentes níveis aminoácidos da alimentação. Todavia, as atividades protease alcalina do fígado e amilase do fígado e intestino anterior não foram detectadas. Estes resultados sugerem que a atividade protease alcalina do intestino anterior seja induzida por aminoácidos liberados na luz do trato digestório. Studies carried out with variation of protein concentration in the fish feed have shown an increase in the activity of alkaline proteases, acid proteases, trypsin and chimotrypsin from the digestive tract of silver catfish (Rhamdia quelen. These facts suggest that products released by digestion in the lumen of this tract can influenced the synthesis and secretion of digestive enzymes. The secretion of these enzymes by the pancreas in vertebrate responses to neural and humoral influences. In the present study, four concentration (0, 3, 6 and 12% of

  11. The Effect of Annealing at 15000C on Migration and Release of Ion Implanted Silver in CVD Silicon Carbide

    International Nuclear Information System (INIS)

    HJ MacLean; RG Ballinger; LE Kolaya; SA Simonson; N Lewis; M Hanson

    2004-01-01

    The transport of silver in CVD β-SiC has been studied using ion implantation. Silver ions were implanted in β-SiC using the ATLAS accelerator facility at the Argonne National Laboratory. Ion beams with energies of 93 and 161 MeV were used to achieve deposition with peak concentrations at depths of approximately 9 and 13 (micro)m, respectively. As-implanted samples were then annealed at 1500 C for 210 or 480 hours. XPS, SEM, TEM, STEM, and optical methods were used to analyze the material before and after annealing. Silver concentration profiles were determined using XPS before and after annealing. STEM and SEM equipped with quantitative chemical analysis capability were used to more fully characterize the location and morphology of the silver before and after annealing. The results show that, within the uncertainty of measurement techniques, there is no silver migration, via either inter- or intragrannular paths, for the times and temperature studied. Additionally, the silver was observed to phase separate within the SiC after annealing. The irradiation damage from the implantation process resulted in a three-layer morphology in the as-implanted condition: (1) a layer of unaltered SiC, followed by (2) a layer of crystallized SiC, followed by (3) an amorphized layer which contained essentially all of the implanted silver. After annealing the layer structure changed. Layer 1 was unaltered. The grains in layer 2 recrystallized to form an epitaxial (columnar) layer. Layer 3 recrystallized to form a fine grain equiaxed layer. The results of this work do not support the long held assumption that silver release from CVD SiC, used for gas-reactor coated particle fuel, is dominated by grain boundary diffusion

  12. Effects of diets containing vegetable protein concentrates on performance and activity of digestive enzymes in silver catfish (Rhamdia quelen

    Directory of Open Access Journals (Sweden)

    Naglezi de Menezes Lovatto

    2014-02-01

    Full Text Available The purpose of study was to evaluate the effect of using protein concentrates crambe and sunflower meal in the diet of silver catfish juveniles, as substitute for animal protein source. A total of 300 silver catfish had been separate in 15 experimental units of 280 L, totaling five treatments with three replications. We evaluated two levels (25% and 50% replacement of the meat and bone meal by protein concentrates of crambe and sunflower meals. Evaluated growth parameters, biological index and digestive enzymes in fish. There was no statistical difference for mass (g and standard length (cm, but the fish diet CPFCr-25% had greater total length (cm. No difference in dry matter, crude protein and total protein deposited (calculated. However, there was a higher concentration of ash in the carcass of the animals fed the control diet and CPFCr-50% in relation to diet CPFG- 50%, in addition, higher levels of lipids in fish fed diet CPFG-50%. No significant differences for hepatosomatic index, digestive somatic index and intestinal quotient of animals subjected to different treatments. The activity of digestive enzymes trypsin and chymotrypsin did not change. There was increased activity of acid protease. The quantitative and qualitative increase in protein concentration from this fraction allows the use of bran protein concentrates crambe and sunflower as substitutes for animal protein source.

  13. Effects of different operating parameters on the particle size of silver chloride nanoparticles prepared in a spinning disk reactor

    Science.gov (United States)

    Dabir, Hossein; Davarpanah, Morteza; Ahmadpour, Ali

    2015-07-01

    The aim of this research was to present an experimental method for large-scale production of silver chloride nanoparticles using spinning disk reactor. Silver nitrate and sodium chloride were used as the reactants, and the protecting agent was gelatin. The experiments were carried out in a continuous mode by injecting the reactants onto the surface of the spinning disk, where a chemical precipitation reaction took place to form AgCl particles. The effects of various operating variables, including supersaturation, disk rotational speed, reactants flow rate, disk diameter, and excess ions, on the particle size of products were investigated. In addition, the AgCl nanoparticles were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. According to the results, smaller AgCl particles are obtained under higher supersaturations and also higher disk rotation speeds. Moreover, in the range of our investigation, the use of lower reactants flow rates and larger disk diameter can reduce the particle size of products. The non-stoichiometric condition of reactants has a significant influence on the reduction in particle aggregation. It was also found that by optimizing the operating conditions, uniform AgCl nanoparticles with the mean size of around 37 nm can be produced.

  14. Observation of feature ripening inversion effect at the percolation threshold for the growth of thin silver films

    Energy Technology Data Exchange (ETDEWEB)

    Nehm, Frederik, E-mail: frederik.nehm@iapp.de; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl

    2014-04-01

    The growth behavior of thin silver films on organic layers is investigated during deposition by means of simultaneous in-situ monitoring of sheet resistance and transmittance. Thermally evaporated films up to 11 nm show a distinct percolation behavior with strong resistance drop at the percolation thickness. Additionally, evaporations are divided into a sequence of one nanometer steps. In the deposition breaks, the films exhibit a ripening effect with an inversion at the percolation thickness, by changing from an increasing to decreasing sheet resistance over time. Scanning electron micrographs suggest same ripening mechanisms for islands below the percolation thickness as for holes above. - Highlights: • Fundamental understanding of metal thin film growth is presented. • Optical and electrical in-situ measurements used for optimizing transparent electrodes • Stepwise Ag deposition reveals extraordinary ripening effects. • Feature ripening inversion is discovered at the percolation threshold.

  15. Observation of feature ripening inversion effect at the percolation threshold for the growth of thin silver films

    International Nuclear Information System (INIS)

    Nehm, Frederik; Schubert, Sylvio; Müller-Meskamp, Lars; Leo, Karl

    2014-01-01

    The growth behavior of thin silver films on organic layers is investigated during deposition by means of simultaneous in-situ monitoring of sheet resistance and transmittance. Thermally evaporated films up to 11 nm show a distinct percolation behavior with strong resistance drop at the percolation thickness. Additionally, evaporations are divided into a sequence of one nanometer steps. In the deposition breaks, the films exhibit a ripening effect with an inversion at the percolation thickness, by changing from an increasing to decreasing sheet resistance over time. Scanning electron micrographs suggest same ripening mechanisms for islands below the percolation thickness as for holes above. - Highlights: • Fundamental understanding of metal thin film growth is presented. • Optical and electrical in-situ measurements used for optimizing transparent electrodes • Stepwise Ag deposition reveals extraordinary ripening effects. • Feature ripening inversion is discovered at the percolation threshold

  16. Green synthesis of silver nanoparticles and investigation of their colorimetric sensing and cytotoxicity effects

    Science.gov (United States)

    Pahlavan Noghabi, Mohammad; Parizadeh, Mohammad Reza; Ghayour-Mobarhan, Majid; Taherzadeh, Danial; Hosseini, Hasan Ali; Darroudi, Majid

    2017-10-01

    The "Green" synthesis of metallic nanoparticles and investigation of their optical properties has become a useful application between nanoscience and medicine. In this work, silver nanoparticles (Ag-NPs) were successfully prepared through a facile and green method by treating silver ions with chitosan. Preparation of Ag-NPs in silver nitrate solution (0.01 M) resulted in small and spherical shapes of Ag-NPs with a mean diameter of 10.2 nm. The formation of Ag-NPs was approved by surface Plasmon resonance (SPR) absorption peaks, using UV-vis spectrophotometer, while Ag-NPs were successfully employed in colorimetric sensing of H2O2 via an analytical procedure. Degradation process of Ag-NPs, encouraged by the catalytic decomposition of H2O2, causes a significant change in the absorbance intensity of SPR band depending on the H2O2 concentration. The cytotoxicity effect of synthesized Ag-NPs was examined on HEK293 cell line. The results illustrate a concentration-dependent toxicity for the tested cells, while15.07 μg/mL of IC50 was obtained.

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

    Science.gov (United States)

    Prasannaraj, Govindaraj; Venkatachalam, Perumal

    2017-02-01

    animals group. Histopathological investigation reveals decreased fat accumulation, appearance of binucleated cells in nanoparticle treated animals and showed mere normal cells induced by DEN. Argyrophilic nucleolar organiser region (AgNORs) had a significant decrease in number of acidic proteins and mast cells assay showed decrease of metachromatic cells in nanoparticles treated animal groups over control. Present results strongly suggest that biomolecule coated silver nanoparticles exposure showed potential hepatoprotective effect against DEN induced liver cancer and could be used as an effective anticancer nanodrug. Copyright © 2017. Published by Elsevier B.V.

  18. 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.

  19. EFFECT OF SILVER NANOPARTICLES ON THE PHYSICAL AND CHEMICAL PROPERTIES OF PLANT OILS AND THEIR ANTIMICROBIAL ACTIVITY

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    V. M. Minarchenko

    2017-12-01

    Full Text Available The aim of our research was to investigate the influence of silver nanoparticles on the physical and chemical features of plant oils of dogrose, flax, cedar, amaranth and watermelon and their antimicrobial activity. Plant oils were saturated with silver nanoparticles using electron-beam technology for depositing a molecular stream of metal in a vacuum. To characterize the rancidity of plant oils, the acid, iodine, peroxide, ester and saponification values were determined. A sharp drop in the iodine number and an increase in the peroxide number in oils saturated with silver nanoparticles were observed, as compared to pure oils, indicating a decrease in the number of unsaturated bonds in fatty acids and the formation of peroxides in oils. All pure plant oils and a separate sample of silver nanoparticles suppressed the growth of only E. faecalis colonies. Plant oils that were saturated with silver nanoparticles delayed the growth of S. aureus, S. epidermidis, E. faecalis, E. coli, P. aeruginosa, and C. albicans; the greatest delay in the growth of colonies was caused by flaxseed oil. Thus, the features of the plant oils under study essentially changed after they are aturated with silver nanoparticles. It can be assumed that the metal acted as a catalyst for peroxide oxidation of lipids in the investigated plant oil samples, the products of which caused toxic effects on cultures of bacteria and fungi in the experiment.

  20. The effect of silver on the optical, spectral-luminescent, and crystallization properties of bromide photo-thermo-refractive glasses

    Science.gov (United States)

    Oreshkina, K. V.; Dubrovin, V. D.; Ignat'ev, A. I.; Nikonorov, N. V.

    2017-10-01

    The effect of silver on the optical, spectral-luminescent, and crystallization properties of bromide photo-thermo-refractive glasses is studied. Multicomponent photosensitive glasses of the Na2O-ZnO-Al2O3-SiO2 system with photosensitizing agents (cerium, antimony, silver) and halogenides (fluorine and bromine) are synthesized. Ultraviolet irradiation and thermal treatment below the glass-transition temperature of the glasses cause the formation of silver molecular clusters, which exhibit luminescence in the visible and infrared regions. UV irradiation and thermal treatment of glasses above the glass-transition temperature lead to the growth of silver nanoparticles with plasmon resonance peak in the region of 420 nm. Further thermal treatment of glasses above the glass-transition temperature shifts the plasmon-resonance maximum by 70 nm to longer wavelengths, which is related to the growth of a crystalline shell consisting of mixed silver and sodium bromides on nanoparticles. This formation of a crystalline phase on colloidal centers results in a local increase in the refractive index of the irradiated region by +Δ n 900 ppm compared to the nonirradiated region. Photo-thermo-refractive glasses with increased silver concentration are promising photosensitive materials for creating holographic optical elements and devices for line narrowing and stabilizing filters, spectral beam combiners, and filters for increasing the spectral brightness of laser diodes. A positive change in the refractive index of Photo-thermo-refractive glasses provides the possibility of recording in them 3D waveguide and integrated-optical structures.

  1. Rapid visual detection of quaternary ammonium surfactants using citrate-capped silver nanoparticles (Ag NPs) based on hydrophobic effect.

    Science.gov (United States)

    Zheng, Li-Qing; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

    2014-01-01

    In this work, a rapid, sensitive and low-cost colorimetric method for detection of quaternary ammonium surfactants using citrate-capped silver nanoparticles (Ag NPs) was developed. The quaternary ammonium surfactants induce the aggregation of Ag NPs through the hydrophobic effect, which is a novel aggregation mechanism of Ag NPs. The addition of cationic surfactant results in color change of Ag NPs solution from yellow to red and finally to colorless, which is due to the broadening of the surface plasmon band. The color change was monitored using a UV-vis spectrophotometer. The LOD of different cationic surfactants was in the range of 0.5-5 µM. More importantly, this detection method was successfully utilized to the disinfectant residual sample. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

  2. Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata.

    Science.gov (United States)

    Monteiro, D R; Gorup, L F; Silva, S; Negri, M; de Camargo, E R; Oliveira, R; Barbosa, D B; Henriques, M

    2011-08-01

    The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4-3.3 μg ml(-1)). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction ∼90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.

  3. Stability of colloidal silver nanoparticles trapped in lipid bilayer: effect of lecithin concentration and applied temperature

    NARCIS (Netherlands)

    Barani, H.; Montazer, M.; Braun, H.G.; Dutschk, Victoria

    2014-01-01

    The use of silver nanoparticle on various substrates has been widespread because of its good antibacterial properties that directly depend on the stability of the silver nanoparticles in a colloidal suspension. In this study, the colloidal solutions of the silver nanoparticles were synthesised by a

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

    Energy Technology Data Exchange (ETDEWEB)

    Sirotinkin, V. P., E-mail: irotinkin.vladimir@mail.ru; Bush, A. A.; Kamentsev, K. E. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation); Dau, H. S. [People’s Friendship University of Russia (Russian Federation); Yakovlev, K. A. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation); Tishchenko, E. A. [People’s Friendship University of Russia (Russian Federation)

    2015-09-15

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

  5. THE EFFECTS OF WATER TEMPERATURE REGIME FLUCTUATIONS ON THE EMBRYONIC DEVELOPMENT OF SILVER CARP (HYPOPHTHALMICHTHYS MOLITRIX

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    А. Vodyanitskyi

    2015-03-01

    Full Text Available Purpose. To determine the effect of temperature regime fluctuations on the development of silver carp embryos, as well as the activity of enzymatic reactions in fish eggs. Methodology. The studies were conducted at the experimental station of the Institute of Hydrobiology of Bila Tserkov, Ukrainian National Academy of Sciences, from June to July. The biological materials were silver carp eggs, embryos and larvae. The dissolved oxygen content was determined using the Winkler method at four o’clock in the morning. Alkalinity phosphatase and LDG activity were determined using a set of reagents «Alkalinity phosphatase» and «LDG» (Phyllis diagnosis, Ukraine. SDH activity was determined by Vexy. The activity of Na, K-Mg-dependent-activated ATPase was determined as growth of inorganic phosphorus in the incubation medium by Kindratova M.N. et al. Protease activity was determined using immune enzymatic method of Tyurina et al. The obtained results were processed statistically in Statistica 5.5, Epaprobit analysis was used for calculating LC/EC values (Version 1.5. Findings The results showed that a delay of embryonic stages of development occur, the number of abnormal embryos increases, and the reproduction efficiency of fish reduces with an increase in water temperature and decrease in the dissolved oxygen content in water. The temperature factor had a significant effect on the activity of key enzymes, in particular the energetic metabolism changed from aerobic to anaerobic. Originality. It was found a negative effect of abiotic factors of water medium and drastic fluctuations in water temperature and gas regime of water bodies on the course of embryogenesis of silver carp that is especially important in the conditions of climate change. Practical value. The obtained results showed that the level of optimum and unfavorable environmental factors during the change of embryonic stages in embryonic and larval fish can be established based on the

  6. Effect of silver nanoparticles and antibiotics on antibiotic resistance genes in anaerobic digestion.

    Science.gov (United States)

    Miller, Jennifer H; Novak, John T; Knocke, William R; Young, Katherine; Hong, Yanjuan; Vikesland, Peter J; Hull, Matthew S; Pruden, Amy

    2013-05-01

    Water resource recovery facilities have been described as creating breeding ground conditions for the selection, transfer, and dissemination of antibiotic resistance genes (ARGs) among various bacteria. The objective of this study was to determine the effect of direct addition of antibiotic and silver nanoparticles (Ag NPs, or nanosilver) on the occurrence of ARGs in thermophilic anaerobic digesters. Test thermophilic digesters were amended with environmentally-relevant concentrations of Ag NP (0.01, 0.1, and 1.0 mg-Ag/L; corresponding to approximately 0.7, 7.0, and 70 mg-Ag/kg total solids) and sulfamethoxazole (SMX) that span susceptible to resistant classifications (1, 5, and 50 mg/L) as potential selection pressures for ARGs. Tetracycline (tet(O), tet(W)) and sulfonamide (sulI, sulII) ARGs and the integrase enzyme gene (intI1) associated with Class 1 integrons were measured in raw sludge, test thermophilic digesters, a control thermophilic digester, and a control mesophilic digester. There was no apparent effect of Ag NPs on thermophilic anaerobic digester performance. The maximum SMX addition (50 mg/L) resulted in accumulation of volatile fatty acids and low pH, alkalinity, and volatile solids reduction. There was no significant difference between ARG gene copy numbers (absolute or normalized to 16S rRNA genes) in amended thermophilic digesters and the control thermophilic digester. Antibiotic resistance gene copy numbers in digested sludge ranged from 10(3) to 10(6) copies per microL (approximately 8 x10(1) to 8 x 10(4) copies per microg) of sludge as result of a 1-log reduction of ARGs (2-log reduction for intI1). Quantities of the five ARGs in raw sludge ranged from 10(4) to 10(8) copies per microL (approximately 4 x 10(2) to 4 x 10(6) per microg) of sludge. Test and control thermophilic digesters (53 degrees C, 12-day solids retention time [SRT]) consistently reduced but did not eliminate levels of all analyzed genes. The mesophilic digester (37 degrees C

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

    Science.gov (United States)

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

    2003-02-01

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

  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. The effectiveness of silver diamine fluoride in arresting caries.

    Science.gov (United States)

    Richards, Derek

    2017-10-27

    Data sourcesPubMed, Embase, Scopus, China National Knowledge Infrastructure (CNKI), Ichushi-web, Biblioteca Virtual en Salud Espana (BVSE) and Biblioteca Virtual em Saude (BVS) databases. There were no limits on language or publication dates.Study selectionTwo reviewers selected prospective clinical studies investigating SDF treatment for caries prevention in children.Data extraction and synthesisData was abstracted independently by two reviewers and risk of bias assessed. Meta-analysis was performed on studies in which the caries-arresting rate using 38% SDF solution on primary teeth could be obtained or calculated.ResultsNineteen studies were included; 16 were conducted in the primary dentition and three in permanent dentition. Fourteen studies used 38% SDF, three 30% SDF, and two 10% SDF. Eight studies using 38% SDF contributed to a meta-analysis and the overall proportion of arrested caries was 81% (95% CI; 68-89%). Percentage reductions were also calculated for 6,12,18,24 and >30 months. Arrested carious lesions stained black but no other adverse effects were reported.ConclusionsSDF commonly used at a high concentration (38%, 44,800ppm fluoride) is effective in arresting caries among children. There is no consensus on its number and frequency of application to arrest caries. Further studies are necessary to develop evidence-based guidelines on its use in children.

  10. Effects of gold and silver backings on the dose rate around an 125I seed

    International Nuclear Information System (INIS)

    Cygler, J.; Szanto, J.; Soubra, M.; Rogers, D.W.

    1990-01-01

    Measurements of the effect of either gold or silver backing on the dose rate around an 125I seed were performed using a Therados RFA7 dosimetry system and a small diode detector which was 2.5 mm in diameter and 0.06 mm thick. It was found that the presence of the gold or silver backing modifies the diode response on the side of the 125I seed away from the backing. The effect depends on the backing material and the distance from the seed. There is a small increase close to the gold backing but a decrease further away. This decrease at distances greater than 10 mm from the seed is uniformly 10%, the same as found when the seed is backed by air. There is an increase of up to 25% observed with silver backing the seed and this increase remains significant more than 30 mm from the seed. When the response increases, the results are hard to interpret quantitatively because of variations in the diode response per unit dose with photon energy and extreme sensitivity to geometric changes. Nonetheless, except for the increase at close distances with the gold, the results are in agreement with EGS4 Monte Carlo photon transport simulations which are for a simplified geometry and account for x-ray fluorescence from the K-shell. Furthermore, the increase in the gold-backed case is qualitatively explained by Williamson's Monte Carlo calculations which take into account the L-shell fluorescent x-rays from gold

  11. 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

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

    Directory of Open Access Journals (Sweden)

    Bianco C

    2015-03-01

    Full Text Available Carlotta Bianco,1 Sanja Kezic,2 Matteo Crosera,1 Vesna Svetličić,3 Suzana Šegota,3 Giovanni Maina,4 Canzio Romano,5 Francesca Larese,6,7 Gianpiero Adami11Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy; 2Academic Medical Center, Coronel Institute, University of Amsterdam, Amsterdam, the Netherlands; 3Laboratory for Bioelectrochemistry and Surface Imaging, Division for Marine and Environmental Research, Ruder Boškovic Institute, Zagreb, Croatia; 4Department of Clinical and Biological Sciences, University of Turin, Turin, Italy; 5Department of Public and Pediatric Health Sciences, University of Turin, Turin, Italy; 6Unit of Occupational Medicine, University of Trieste, Trieste, Italy; 7Department of Medical Sciences, University of Trieste, Trieste, ItalyAbstract: The objective of this study was to determine the in vitro percutaneous penetration of silver and characterize the silver species released from textiles in different layers of full thickness human skin. For this purpose, two different wound dressings and a garment soaked in artificial sweat were placed in the donor compartments of Franz cells for 24 hours. The concentration of silver in the donor phase and in the skin was determined by an electrothermal atomic absorption spectrometer (ET-AAS and by inductively coupled plasma mass spectrometer (ICP-MS. The characterization of silver species in the textiles and in the skin layers was made by scanning electron microscopy with integrated energy dispersive X-ray spectroscopy (SEM-EDX. Additionally, the size distribution of silver nanoparticles in the textiles was performed by atomic force microscopy (AFM. On the surface of all investigated materials, silver nanoparticles of different size and morphology were found. Released silver concentrations in the soaking solutions (ie, exposure concentration ranged from 0.7 to 4.7 µg/mL (0.6–4.0 µg/cm2, fitting the bactericidal range. Silver and silver

  13. Chelating effect of silver nitrate by chitosan on its toxicity and growth performance in broiler chickens

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    Yemdjie Mane Divine Doriane

    2017-06-01

    Full Text Available Objective: This study was conducted to investigate the chelating effect of silver nitrate (AgNO3 by chitosan on growth performances, hematological and biochemical parameters, and the histopathological structure of the liver and the kidney in broiler chicken. Materials and methods: A total of 192 day-old Cobb 500 strain chicks were randomly assigned to 3 treatments of 64 chicks each. Control group was fed on basal diet without supplement (R0 and the two others groups were fed on rations supplemented with 10 mg of unchelated (RAg or chelated (RCs-Ag AgNO3 per Kg of feed, respectively. Parameters that have been studied consisted of feed intake, weight gain, blood and serum biochemical, and histopathological analyses of liver and kidney. Results: Results revealed that chelation of AgNO3 by chitosan did not have any effect on growth performances and hematological parameters in chicken. However, chelated and unchelated AgNO3 increased the serum content in triglyceride, and cholesterol and decreased the serum content in creatinin, albumin and alanine aminotransferase (ALAT. Chelating AgNO3 with chitosan prevented and corrected the toxicity induced on the histological structure of liver and kidney. Conclusion: Chitosan can be used as a chelating agent to alleviate the harmful effects of AgNO3 as silver ion for poultry. [J Adv Vet Anim Res 2017; 4(2.000: 187-193

  14. 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

  15. Towards conducting inks: Polypyrrole–silver colloids

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  16. Antibacterial effects of hydrogen peroxide and silver composition on selected pathogenic enterobacteriaceae

    Directory of Open Access Journals (Sweden)

    Mojtaba Davoudi

    2012-01-01

    Full Text Available Aims: Antibacterial effects of hydrogen peroxide and silver composition on selected pathogenic enterobacteriaceae was investigated in this study. Materials and Methods: The efficacy of 30 ppb silver in 0.3% hydrogen peroxide solution for inactivation of selected Enterobacteriaceae, including Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae was assessed for 72 hours in a designated nutrient broth medium and steel surface. The bactericidal growth ability was determined for each bacterium genus by the conventional colony count method and turbidimetry via an optical density (OD assay at 450 nm in a time interval of 24 hours. Results: Suspensions of K.pneumoniae, and P.mirabilis showed a significant OD reduction at three 24-hour intervals (CI = 0.95; P < 0.05, for both, along with blocked growth in a designated broth medium during 24 to 48 hours of exposure. The disinfectant was also significantly efficient for inactivating of the mentioned bacteria on steel surfaces after a 15-minute time exposure (CI = 0.95; P < 0.05. For E.coli, the OD decreased slightly during the initial exposure time, but increased after 24 hours. Viable E.coli cells were proved by colonies grown on the plate. A qualitative surface decontamination test showed that three pathogenic bacteria were inactivated significantly after disinfectant exposure (CI = 0.95, P < 0.05. Conclusions: In conclusion, a combination of hydrogen peroxide and silver ions was proposed as a strong disinfecting agent both in suspensions and on the surfaces against these three important human pathogens.

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

    Science.gov (United States)

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

    2014-09-01

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

  18. Optimization for extracellular biosynthesis of silver nanoparticles by Penicillium aculeatum Su1 and their antimicrobial activity and cytotoxic effect compared with silver ions.

    Science.gov (United States)

    Ma, Liang; Su, Wei; Liu, Jian-Xin; Zeng, Xiao-Xi; Huang, Zhi; Li, Wen; Liu, Zheng-Chun; Tang, Jian-Xin

    2017-08-01

    The present study addresses an eco-friendly and energy-saving method for extracellular biosynthesis of silver nanoparticles (AgNPs) using a cell free filtrate of the fungus strain Penicillium aculeatum Su1 as a reducing agent. Parametric optimization of the biosynthesis process demonstrated different effects on the size, distribution, yield, and synthesis rate of biosynthesized AgNPs. The transmission electron microscopy (TEM) measurements demonstrated that AgNPs were spherical or approximately spherical, with a size between 4 and 55nm. High-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analyses indicated that AgNPs were nanocrystalline by nature, with the character of a face-centered cubic (fcc). Fourier transform infrared spectroscopy (FTIR) analysis confirmed the existence of protein molecules that acted as a reducing agent and a capping agent during the biosynthesis process. Furthermore, the biosynthesized AgNPs exhibited higher antimicrobial activity than silver ions against Gram negative bacteria, Gram positive bacteria and fungi. Compared with silver ions, the biosynthesized AgNPs presented higher biocompatibility toward human bronchial epithelial (HBE) cells and high cytotoxicity in a dose-dependent manner with an IC 50 of 48.73μg/mL toward A549 cells. These results demonstrate that Penicillium aculeatum Su1 is a potential bioresource that can be used to produce low-cost and eco-friendly AgNPs as efficient antimicrobial agent, drug delivery vehicle or anticancer drug for clinic treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. [Study of the effect of colloidal solution of silver nanoparticles on parameters of cardio- and hemo-dynamics in rabbits].

    Science.gov (United States)

    Pryskoka, A O

    2014-01-01

    Metal nanoparticles and silver nanoparticles in particular are extensively studied recently considering their prominent antimicrobial properties. Nevertheless, their toxicity aspects and probable side effects remain not well studied. In this article the results of study of the influence of silver nanoparticles onto a cardiovascular system in an in vivo experiment were provided, changes in parameters of cardio- and hemodynamics were defined, and the principles of such influence were identified. Dose-dependent effect of these nanoparticles was established when administered in dose of 4.3 mg/kg three times and 20 mg/kg once.

  20. Chronic effect of waterborne colloidal silver nanoparticles on plasma biochemistry and hematology of rainbow trout (Oncorhynchus mykiss

    Directory of Open Access Journals (Sweden)

    Seyed Ali Johari

    2016-05-01

    Full Text Available Objective: To investigate the possible effects of silver nanoparticles (AgNPs on some blood and plasma indices of rainbow trout (Oncorhynchus mykiss. Methods: Hence, fish were exposed for 21 days to sub-lethal concentrations of colloidal AgNPs and blood parameters including erythrocyte size and hematocrit, plasma parameters including cholinesterase, cortisol, sodium, chloride, and potassium, and also silver concentration in plasma were measured following the 11th and 21st days of exposure. Results: According to the results of present study, higher concentrations of AgNPs had more significant effects on plasma biochemistry and hematology of trout. The greatest impacts were decline of chloride ions and increase of cortisol and cholinesterase. Also fish exposed to AgNPs significantly increased silver concentration in the plasma. Conclusions: Further studies are needed to identify appropriate blood biomarkers following fish exposed to nanomaterials, especially AgNPs.

  1. Ambipolar transport of silver nanoparticles decorated graphene oxide field effect transistors

    Science.gov (United States)

    Sarkar, Kalyan Jyoti; Sarkar, K.; Pal, B.; Kumar, Aparabal; Das, Anish; Banerji, P.

    2018-05-01

    In this article, we report ambipolar field effect transistor (FET) by using graphene oxide (GO) as a gate dielectric material for silver nanoparticles (AgNPs) decorated GO channel layer. GO was synthesized by Hummers' method. The AgNPs were prepared via photochemical reduction of silver nitrate solution by using monoethanolamine as a reducing agent. Morphological properties of channel layer were characterized by Field Effect Scanning Electron Microscopy (FESEM). Fourier Transform Infrared Spectroscopy (FTIR) was carried out to characterize GO thin film. For device fabrication gold (Au) was deposited as source-drain contact and aluminum (Al) was taken as bottom contact. Electrical measurements were performed by back gate configuration. Ambipolar transport behavior was explained from transfer characteristics. A maximum electron mobiliy of 6.65 cm2/Vs and a hole mobility of 2.46 cm2/Vs were extracted from the transfer characteristics. These results suggest that GO is a potential candidate as a gate dielectric material for thin film transistor applications and also provides new insights in GO based research.

  2. Particulate Respirators Functionalized with Silver Nanoparticles Showed Excellent Real-Time Antimicrobial Effects against Pathogens.

    Science.gov (United States)

    Zheng, Clark Renjun; Li, Shuai; Ye, Chengsong; Li, Xinyang; Zhang, Chiqian; Yu, Xin

    2016-07-05

    Particulate respirators designed to filtrate fine particulate matters usually do not possess antimicrobial functions. The current study aimed to functionalize particulate respirators with silver nanoparticles (nanosilver or AgNPs), which have excellent antimicrobial activities, utilizing a straightforward and effective method. We first enhanced the nanosilver-coating ability of nonwoven fabrics from a particulate respirator through surface modification by sodium oleate. The surfactant treatment significantly improved the fabrics' water wet preference where the static water contact angles reduced from 122° to 56°. Both macroscopic agar-plate tests and microscopic scanning electron microscope (SEM) characterization revealed that nanosilver functionalized fabrics could effectively inhibit the growth of two model bacterial strains (i.e., Staphylococcus aureus and Pseudomonas aeruginosa). The coating of silver nanoparticles would not affect the main function of particulate respirators (i.e., filtration of fine air-borne particles). Nanosilver coated particulate respirators with excellent antimicrobial activities can provide real-time protection to people in regions with severe air pollution against air-borne pathogens.

  3. Biosynthesis, characterization, and antimicrobial applications of silver nanoparticles.

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Lianchao Zhang

    2015-01-01

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

  5. The effect of a honey based gel and silver sulphadiazine on bacterial infections of in vitro burn wounds

    NARCIS (Netherlands)

    Boekema, B.K.H.L.; Pool, L.; Ulrich, M.

    2013-01-01

    Bacterial contamination remains a constant threat in burn wound care. Topical treatments to combat contaminations have good bactericidal effects but can have detrimental effects for the healing process. Treatments with for example silver can increase healing times. Honey based products can be a good

  6. Ballistic-type field penetration into metals illustrated by high- and low-frequency size-effect measurements in silver

    DEFF Research Database (Denmark)

    Gantmakher, V. F.; Lebech, Jens; Bak, Christen Kjeldahl

    1979-01-01

    Radio-frequency size-effect experiments were performed on silver plane-parallel plates at high, 45 GHz, and low, 3 MHz, frequencies. By investigation of size-effect structures we show the influence of frequency on the field distribution inside the metal. When the frequency increases, the splash...

  7. Qualitative bacteriology in malignant wounds- a prospective, randomized, clinical study to compare the effect of honey and silver dressings

    DEFF Research Database (Denmark)

    Lund-Nielsen, Betina; Adamsen, Lis; Gottrup, Finn

    2011-01-01

    ¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿ Between 5% and 10% of cancer patients develop malignant wounds. In vitro and some clinical studies suggest that silver- or honey-coated dressings may have an antibacterial effect in nonmalignant wounds, but their possible antibacterial effect in malignant wounds remains unknown. ...

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

    Science.gov (United States)

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

    2017-08-01

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

  9. Mosquitocidal and antibacterial activity of green-synthesized silver nanoparticles from Aloe vera extracts: towards an effective tool against the malaria vector Anopheles stephensi?

    Science.gov (United States)

    Dinesh, Devakumar; Murugan, Kadarkarai; Madhiyazhagan, Pari; Panneerselvam, Chellasamy; Kumar, Palanisamy Mahesh; Nicoletti, Marcello; Jiang, Wei; Benelli, Giovanni; Chandramohan, Balamurugan; Suresh, Udaiyan

    2015-04-01

    Mosquitoes represent an important threat for lives of millions of people worldwide, acting as vectors for devastating pathogens, such as malaria, yellow fever, dengue, and West Nile. In addition, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. Here, we investigated the mosquitocidal and antibacterial properties of Aloe vera leaf extract and silver nanoparticles synthesized using A. vera extract. Mosquitocidal properties were assessed in laboratory against larvae (I-IV instar) and pupae of the malaria vector Anopheles stephensi. Green-synthesized silver nanoparticles were tested against An. stephensi also in field conditions. Antibacterial properties of nanoparticles were evaluated against Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. The synthesized silver nanoparticles were characterized by UV-vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In laboratory conditions, the A. vera extract was toxic against An. stephensi larvae and pupae, even at low dosages. LC50 were 48.79 ppm (I instar), 59.09 ppm (II instar), 70.88 ppm (III instar), 83.58 ppm (IV instar), and 152.55 ppm (pupae). Green-synthesized silver nanoparticles were highly toxic against An. stephensi. LC50 were 3.825 ppm (I instar), 4.119 ppm (II instar), 4.982 ppm (III instar), 5.711 ppm (IV instar), and 6.113 ppm (pupae). In field conditions, the application of A. vera-synthesized silver nanoparticles (10 × LC50) leads to An. stephensi larval reduction of 74.5, 86.6, and 97.7%, after 24, 48, and 72 h, respectively. Nanoparticles also showed antibacterial properties, and the maximum concentration tested (150 mg/L) evoked an inhibition zone wider than 80 mm in all tested bacterium species. This study adds knowledge about the use of green synthesis of nanoparticles in

  10. Effect of temperature on the synthesis of silver nanoparticles with polyethylene glycol: new insights into the reduction mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Fleitas-Salazar, Noralvis; Silva-Campa, Erika; Pedroso-Santana, Seidy; Tanori, Judith; Pedroza-Montero, Martín R.; Riera, Raúl, E-mail: rriera@cifus.uson.mx [Universidad de Sonora (Mexico)

    2017-03-15

    Polyethylene glycol (PEG) molecules act as a reducing and stabilizing agent in the formation of silver nanoparticles. PEG undergoes thermal oxidative degradation at temperatures over 70 °C in the presence of oxygen. Here, we studied how the temperature and an oxidizing atmosphere could affect the synthesis of silver nanoparticles with PEG. We tested different AgNO{sub 3} concentrations for nanoparticles syntheses using PEG of low molecular weight, at 60 and 100 °C. At the higher temperature, the reducing action of PEG increased and the effect of PEG/Ag{sup +} ratio on nanoparticles aggregation changed. These results suggest that different synthesis mechanisms operate at 60 and 100 °C. Thus, at 60 °C the reduction of silver ions can occur through the oxidation of the hydroxyl groups of PEG, as has been previously reported. We propose that the thermal oxidative degradation of PEG at 100 °C increases the number of both, functional groups and molecules that can reduce silver ions and stabilize silver nanoparticles. This degradation process could explain the enhancement of PEG reducing action observed by other authors when they increase the reaction temperature or use a PEG of higher molecular weight.

  11. Effect of the size of silver nanoparticles on SERS signal enhancement

    Science.gov (United States)

    He, Rui Xiu; Liang, Robert; Peng, Peng; Norman Zhou, Y.

    2017-08-01

    The localized surface plasmon resonance arising from plasmonic materials is beneficial in solution-based and thin-film sensing applications, which increase the sensitivity of the analyte being tested. Silver nanoparticles from 35 to 65 nm in diameter were synthesized using a low-temperature method and deposited in a monolayer on a (3-aminopropyl)triethoxysilane (APTES)-functionalized glass slide. The effect of particle size on monolayer structure, optical behavior, and surface-enhanced Raman scattering (SERS) is studied. While increasing particle size decreases particle coverage, it also changes the localized surface plasmon resonance and thus the SERS activity of individual nanoparticles. Using a laser excitation wavelength of 633 nm, the stronger localized surface plasmon resonance coupling to this excitation wavelength at larger particle sizes trumps the loss in surface coverage, and greater SERS signals are observed. The SERS signal enhancement accounts for the higher SERS signal, which was verified using a finite element model of a silver nanoparticle dimer with various nanoparticle sizes and separation distances.

  12. Protein Corona Analysis of Silver Nanoparticles Links to Their Cellular Effects.

    Science.gov (United States)

    Juling, Sabine; Niedzwiecka, Alicia; Böhmert, Linda; Lichtenstein, Dajana; Selve, Sören; Braeuning, Albert; Thünemann, Andreas F; Krause, Eberhard; Lampen, Alfonso

    2017-11-03

    The breadth of applications of nanoparticles and the access to food-associated consumer products containing nanosized materials lead to oral human exposure to such particles. In biological fluids nanoparticles dynamically interact with biomolecules and form a protein corona. Knowledge about the protein corona is of great interest for understanding the molecular effects of particles as well as their fate inside the human body. We used a mass spectrometry-based toxicoproteomics approach to elucidate mechanisms of toxicity of silver nanoparticles and to comprehensively characterize the protein corona formed around silver nanoparticles in Caco-2 human intestinal epithelial cells. Results were compared with respect to the cellular function of proteins either affected by exposure to nanoparticles or present in the protein corona. A transcriptomic data set was included in the analyses in order to obtain a combined multiomics view of nanoparticle-affected cellular processes. A relationship between corona proteins and the proteomic or transcriptomic responses was revealed, showing that differentially regulated proteins or transcripts were engaged in the same cellular signaling pathways. Protein corona analyses of nanoparticles in cells might therefore help in obtaining information about the molecular consequences of nanoparticle treatment.

  13. Fabrication of Sesame Sticks-like Silver Nanoparticles/Polystyrene Hybridnanotubes and Their Catalytic Effects.

    Science.gov (United States)

    Peng, Fang; Wang, Qi; Shi, Rongjia; Wang, Zeyi; You, Xin; Liu, Yuhong; Wang, Fenghe; Gao, Jay; Mao, Chun

    2016-12-21

    A novel and efficient catalyst is one of the goals in the material field, and the involvement of nanoscience and technology has brought new vigor to the development of catalyst. This research aimed to develop a simple two-step route to fabricate Fe 3 O 4 @PS/PDA-Ag hybridnanotubes with size-controllable and highly dispersed silver nanoparticles (NPs). First, Fe 3 O 4 @PS nanotubes of a sound mechanical property were prepared using polystyrene (PS)/toluene solution containing highly dispersed oleic acid modified Fe 3 O 4 particles in a commercial AAO template. Next, the facile technique was used to form in situ silver NPs on the surface of magnetic PS (Fe 3 O 4 @PS) nanotubes through dopamine coating. The catalytic effects of the prepared Fe 3 O 4 @PS/PDA-Ag hybridnanotubes with highly dispersed AgNPs were characterized using a range of analytical methods, including transmission electron microscopy, thermogravimetric analysis, UV-Visible spectroscopy, and X-ray diffraction. It was found that such prepared Fe 3 O 4 @PS/PDA-Ag hybridnanotubes had a large specific surface area. They possessed excellent activities in catalyzing the reduction of 4-nitrophenol (4-NP) by NaBH 4 in the aqueous phase. Furthermore, they were readily separated from fluid and retrieved by an external magnet. Their catalyst activity and recyclability demonstrated that this approach we proposed had the potential to become a new idea and route for catalytic platform.

  14. Two-step synthesis of silver selenide semiconductor with a linear magnetoresistance effect

    International Nuclear Information System (INIS)

    Yang, Fengxia; Xiong, Shuangtao; Liu, Fengxian; Han, Chong; Zhang, Duanming; Xia, Zhengcai

    2012-01-01

    A two-step synthesis method for polycrystalline β-silver selenide (β-Ag 2 Se) was developed. In the first step, nanopowder was prepared using a chemical conversion method at room temperature. In the second step, the nanopowder was compressed and then the bulk Ag 2 Se was fabricated by the solid-state sintering process. The crystalline phase and morphology were examined. The results showed that β-Ag 2 Se was fast fabricated at room temperature. The dense polycrystalline Ag-rich Ag 2 Se was synthesized successfully at 450 °C for 0.5 h under Argon flow. For the polycrystalline, the electronic properties and transverse magnetoresistance (TMR) in a pulsed magnetic field were investigated. The samples displayed n-type semiconducting behaviors and a critical temperature with a broaden temperature range of 140–150 K. Also, it presented a positive and nearly linear dependence on magnetic field H at H ≥ H c (crossover field) ranging from 2 to 20 T. Moreover, the linear dependence of TMR at strong field was non-saturating up to 35 T. Combining with the observation of morphology, it is thought that this unusual TMR effect was caused by slightly excess Ag. This new synthesis method provided a potential route to synthesize nonstoichiometric silver selenide. (paper)

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

    Science.gov (United States)

    Aguilar-Méndez, Miguel A.; San Martín-Martínez, Eduardo; Ortega-Arroyo, Lesli; Cobián-Portillo, Georgina; Sánchez-Espíndola, Esther

    2011-06-01

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

  16. Drag reduction by natural polymeric additives in PMDS microchannel: Effect of types of additives

    OpenAIRE

    Ling Fiona W.M.; Abdulbari Hayder A.

    2017-01-01

    Drag reduction technology was used in medical applications to enhance the blood flow in semiclogged blood streams which can be an alternative treatment for atherosclerosis. In this present study, natural polymeric drag reducing additives (DRA) was introduced to replace synthetic polymer which has the possibility of bringing side effects to human health. Three different sources, namely okra, aloe vera and hibiscus were utilized to extract the natural polymeric additives which were then tested ...

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

    Science.gov (United States)

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

    2016-09-29

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

  18. Electromagnetic shielding effectiveness of a thin silver layer deposited onto PET film via atmospheric pressure plasma reduction

    Science.gov (United States)

    Oh, Hyo-Jun; Dao, Van-Duong; Choi, Ho-Suk

    2018-03-01

    This study presents the first use of a plasma reduction reaction under atmospheric pressure to fabricate a thin silver layer on polyethylene terephthalate (PET) film without the use of toxic chemicals, high voltages, or an expensive vacuum apparatus. The developed film is applied to electromagnetic interference (EMI) shielding. After repeatedly depositing a silver layer through a plasma reduction reaction on PET, we can successfully fabricate a uniformly deposited thin silver layer. It was found that both the particle size and film thickness of thin silver layers fabricated at different AgNO3 concentrations increase with an increase in the concentration of AgNO3. However, the roughness of the thin silver layer decreases when increasing the concentration of AgNO3 from 100 to 500 mM, and the roughness increases with a further increase in the concentration of AgNO3. The EMI shielding effectiveness (SE) of the film is measured in the frequency range of 0.045 to 1 GHz. As a result of optimizing the electrical conductivity by measuring sheet resistance of the thin silver layer, the film fabricated from 500 mM AgNO3 exhibits the highest EMI SE among all fabricated films. The maximum values of the EMI SE are 60.490 dB at 0.1 GHz and 54.721 dB at 1.0 GHz with minimum sheet resistance of 0.244 Ω/□. Given that the proposed strategy is simple and effective, it is promising for fabricating various low-cost metal films with high EMI SE.

  19. The interaction between silver and N2O in relation to the oxidative dehydrogenation of methanol

    NARCIS (Netherlands)

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

    1988-01-01

    The interaction of N2O with pure silver at temperatures up to 900 °C has been studied using temperature-programmed reduction and desorption; the interaction is compared with that of oxygen with silver. The effect of addition of N2O, as well as of the complete replacement of oxygen by N2O, on the

  20. Migration under the effect of an electric field of 110Ag and 124Sb in silver

    International Nuclear Information System (INIS)

    Nguyen Van, Doan; Brebec, G.

    1968-04-01

    The most recent theories relative to the influence of an electric field on the migration of point defects in metals are briefly recalled stressing their similarities and the different hypotheses on which they are based. In order to relate the various physical constants of the phenomenon, the flux of a solute is expressed in terms of diffusion coefficients and 'effective valences' defined in thermodynamics of irreversible processes. Experimental results on the electromigration of 124 Sb and 110 Ag in silver show that these atoms migrate towards the anode with effective valences of - 95 and - 16 respectively for 124 Sb and 110 Ag at temperatures in the region of 900 deg. C. Estimates were made on the resistivities that should be used in the different theories in order to compare their predictions with experimental results. (authors) [fr

  1. Inhibitory effects of silver zeolite on in vitro growth of fish egg pathogen, Saprolegnia sp.

    Directory of Open Access Journals (Sweden)

    Seyed Ali Johari

    2014-05-01

    Full Text Available Objective: To investigate the effects of powdered silver zeolite (SZ on the in vitro growth of the fish pathogen Saprolegnia sp. Methods: The antifungal activity of SZ was evaluated by determining the minimum inhibitory concentrations using two-fold serial dilutions of powdered SZ in a glucose yeast extract agar at 22 °C. The growth of Saprolegnia sp. on the SZ agar treatments was compared to that on SZ-free agar controls. Results: The results showed that SZ had an inhibitory effect on the in vitro growth of the tested fungi. The minimum inhibitory concentration of SZ for Saprolegnia sp. was also calculated at 600 mg/L, which is equal to 0.06 percent. Conclusions: SZ is a potential good candidate to replace teratogenic and toxic agents, such as malachite green in aquaculture systems.

  2. 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.

  3. Low concentrations of silver nanoparticles have a beneficial effect on wound healing in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ambrožová, Nikola [Palacký University, Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry (Czech Republic); Zálešák, Bohumil [University Hospital Olomouc, Department of Plastic and Aesthetic Surgery (Czech Republic); Ulrichová, Jitka [Palacký University, Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry (Czech Republic); Čížková, Kateřina [Palacký University, Department of Histology and Embryology, Faculty of Medicine and Dentistry (Czech Republic); Galandáková, Adéla, E-mail: galandakova.a@seznam.cz [Palacký University, Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry (Czech Republic)

    2017-03-15

    Silver has been used in medical application for its antibacterial, antifungal, and anti-inflammatory effects. Silver nanoparticles (AgNPs) are currently in the spotlight. It was shown that their application can be useful in the management of wounds. Our study was conducted to determine whether AgNPs (average size 10.43 ± 4.74 nm) and ionic silver (Ag-I) could affect the wound healing in the in vitro model of normal human dermal fibroblasts (NHDF). We evaluated their effect on reactive oxygen species (ROS) generation and the expression of key transcription factors that coordinate the cellular response to oxidative stress [nuclear factor (erythroid-derived 2)-like 2 (Nrf2)] and inflammation [nuclear factor-κB (NF-κB)], expression of heme oxygenase-1 (HO-1), and interleukin-6 (IL-6) level. Isolated primary NHDF were scratched, heated (1 h; 42 °C), and cultured with AgNPs (0.25, 2.5, and 25 μg/ml) and Ag-I (0.025, 0.1, and 0.25 μg/ml) for 8 or 24 h. The ROS generation, Nrf2, NF-κB, and HO-1 protein expression and IL-6 protein level were then evaluated by standard methods. Non-cytotoxic concentrations of AgNPs (0.25 and 2.5 μg/ml) did not affect the ROS generation but activated the Nrf2/HO-1 pathway and decreased the NF-κB expression and IL-6 level in the in vitro wound healing model. AgNPs at concentrations of 0.25 and 2.5 μg/ml seem to be suitable for the intended application as a topical agent for wound healing, although the gene silencing technique, chemical inhibitors, and detailed time- and concentration-dependent experiments are needed for a comprehensive study of signaling pathway regulation. Further investigation is also necessary to exclude any possible adverse effects.

  4. Low concentrations of silver nanoparticles have a beneficial effect on wound healing in vitro

    International Nuclear Information System (INIS)

    Ambrožová, Nikola; Zálešák, Bohumil; Ulrichová, Jitka; Čížková, Kateřina; Galandáková, Adéla

    2017-01-01

    Silver has been used in medical application for its antibacterial, antifungal, and anti-inflammatory effects. Silver nanoparticles (AgNPs) are currently in the spotlight. It was shown that their application can be useful in the management of wounds. Our study was conducted to determine whether AgNPs (average size 10.43 ± 4.74 nm) and ionic silver (Ag-I) could affect the wound healing in the in vitro model of normal human dermal fibroblasts (NHDF). We evaluated their effect on reactive oxygen species (ROS) generation and the expression of key transcription factors that coordinate the cellular response to oxidative stress [nuclear factor (erythroid-derived 2)-like 2 (Nrf2)] and inflammation [nuclear factor-κB (NF-κB)], expression of heme oxygenase-1 (HO-1), and interleukin-6 (IL-6) level. Isolated primary NHDF were scratched, heated (1 h; 42 °C), and cultured with AgNPs (0.25, 2.5, and 25 μg/ml) and Ag-I (0.025, 0.1, and 0.25 μg/ml) for 8 or 24 h. The ROS generation, Nrf2, NF-κB, and HO-1 protein expression and IL-6 protein level were then evaluated by standard methods. Non-cytotoxic concentrations of AgNPs (0.25 and 2.5 μg/ml) did not affect the ROS generation but activated the Nrf2/HO-1 pathway and decreased the NF-κB expression and IL-6 level in the in vitro wound healing model. AgNPs at concentrations of 0.25 and 2.5 μg/ml seem to be suitable for the intended application as a topical agent for wound healing, although the gene silencing technique, chemical inhibitors, and detailed time- and concentration-dependent experiments are needed for a comprehensive study of signaling pathway regulation. Further investigation is also necessary to exclude any possible adverse effects.

  5. Long-term effects of sulfidized silver nanoparticles in sewage sludge on soil microflora.

    Science.gov (United States)

    Kraas, Marco; Schlich, Karsten; Knopf, Burkhard; Wege, Franziska; Kägi, Ralf; Terytze, Konstantin; Hund-Rinke, Kerstin

    2017-12-01

    The use of silver nanoparticles (AgNPs) in consumer products such as textiles leads to their discharge into wastewater and consequently to a transfer of the AgNPs to soil ecosystems via biosolids used as fertilizer. In urban wastewater systems (e.g., sewer, wastewater treatment plant [WWTP], anaerobic digesters) AgNPs are efficiently converted into sparingly soluble silver sulfides (Ag 2 S), mitigating the toxicity of the AgNPs. However, long-term studies on the bioavailability and effects of sulfidized AgNPs on soil microorganisms are lacking. Thus we investigated the bioavailability and long-term effects of AgNPs (spiked in a laboratory WWTP) on soil microorganisms. Before mixing the biosolids into soil, the sludges were either anaerobically digested or directly dewatered. The effects on the ammonium oxidation process were investigated over 140 d. Transmission electron microscopy (TEM) suggested an almost complete sulfidation of the AgNPs analyzed in all biosolid samples and in soil, with Ag 2 S predominantly detected in long-term incubation experiments. However, despite the sulfidation of the AgNPs, soil ammonium oxidation was significantly inhibited, and the degree of inhibition was independent of the sludge treatment. The results revealed that AgNPs sulfidized under environmentally relevant conditions were still bioavailable to soil microorganisms. Consequently, Ag 2 S may exhibit toxic effects over the long term rather than the short term. Environ Toxicol Chem 2017;36:3305-3313. © 2017 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC. © 2017 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

  6. Bacterial transmission from lens storage cases to contact lenses - Effects of lens care solutions and silver impregnation of cases

    NARCIS (Netherlands)

    Vermeltfoort, Pit B. J.; Hooymans, Johanna M. M.; Busscher, Henk J.; van der Mei, Henny C.

    2008-01-01

    The killing efficacies of multipurpose lens care solutions on planktonic and biofilm bacteria grown in polypropylene contact lens storage cases with and without silver impregnation and effects on bacterial transmission from storage cases to silicone hydrogel contact lenses were investigated. For

  7. Tuning the localized surface plasmon resonance of silver nanoplatelet colloids

    International Nuclear Information System (INIS)

    Singh, Asha; Jayabalan, J; Chari, Rama; Srivastava, Himanshu; Oak, S M

    2010-01-01

    The effect of femtosecond laser irradiation on silver nanoplatelet colloids is described. It is shown that irradiation with a femtosecond laser of appropriate fluence can be used to tune the localized surface plasmon resonances of triangular silver nanoplatelets by a few tens of nanometres. This peak shift is shown to be caused by the structural modifications of the particle tips. We have also shown that post-preparation addition of poly-vinyl pyrrolidone to the nanocolloid arrests the peak shift.

  8. Tuning the localized surface plasmon resonance of silver nanoplatelet colloids

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Asha; Jayabalan, J; Chari, Rama [Laser Physics Applications Division, Raja Ramanna Centre for Advanced Technology, Indore (India); Srivastava, Himanshu [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore (India); Oak, S M, E-mail: jjaya@rrcat.gov.i [Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore (India)

    2010-08-25

    The effect of femtosecond laser irradiation on silver nanoplatelet colloids is described. It is shown that irradiation with a femtosecond laser of appropriate fluence can be used to tune the localized surface plasmon resonances of triangular silver nanoplatelets by a few tens of nanometres. This peak shift is shown to be caused by the structural modifications of the particle tips. We have also shown that post-preparation addition of poly-vinyl pyrrolidone to the nanocolloid arrests the peak shift.

  9. Drag reduction by natural polymeric additives in PMDS microchannel: Effect of types of additives

    Directory of Open Access Journals (Sweden)

    Ling Fiona W.M.

    2017-01-01

    Full Text Available Drag reduction technology was used in medical applications to enhance the blood flow in semiclogged blood streams which can be an alternative treatment for atherosclerosis. In this present study, natural polymeric drag reducing additives (DRA was introduced to replace synthetic polymer which has the possibility of bringing side effects to human health. Three different sources, namely okra, aloe vera and hibiscus were utilized to extract the natural polymeric additives which were then tested in custom made microchannel simulating human heart blood vessels. The performance of different types of additives was evaluated using pressure measurements. The maximum drag reduction up to 63.48% is achieved using 300 ppm of hibiscus mucilage at operating pressure of 50 mbar. In this present work, hibiscus showed the best drag reduction performance, giving the highest %FI in most of the cases. This experimental results proved that these natural polymeric additives could be utilized as DRA in enhancing the blood flow in semiclogged blood streams.

  10. Silver nanoparticles with antimicrobial activities against Streptococcus mutans and their cytotoxic effect

    Energy Technology Data Exchange (ETDEWEB)

    Pérez-Díaz, Mario Alberto [Facultad de Ciencias Químicas, UASLP, Álvaro Obregón 64, San Luis Potosí (Mexico); Boegli, Laura; James, Garth [Center for Biofilm Engineering, Montana State University, Bozeman, MT (United States); Velasquillo, Cristina; Sánchez-Sánchez, Roberto [Laboratorio de Biotecnología, Instituto Nacional de Rehabilitación (Mexico); Martínez-Martínez, Rita-Elizabeth; Martínez-Castañón, Gabriel Alejandro [Facultad de Estomatología, Universidad Autónoma de San Luis Potosí (Mexico); Martinez-Gutierrez, Fidel, E-mail: fidel@uaslp.mx [Facultad de Ciencias Químicas, UASLP, Álvaro Obregón 64, San Luis Potosí (Mexico)

    2015-10-01

    Microbial resistance represents a challenge for the scientific community to develop new bioactive compounds. The goal of this research was to evaluate the antimicrobial activity of silver nanoparticles (AgNPs) against a clinical isolate of Streptococcus mutans, antibiofilm activity against mature S. mutans biofilms and the compatibility with human fibroblasts. The antimicrobial activity of AgNPs against the planktonic clinical isolate was size and concentration dependent, with smaller AgNPs having a lower minimum inhibitory concentration. A reduction of 2.3 log in the number of colony-forming units of S. mutans was observed when biofilms grown in a CDC reactor were exposed to 100 ppm of AgNPs of 9.5 ± 1.1 nm. However, AgNPs at high concentrations (> 10 ppm) showed a cytotoxic effect upon human dermal fibroblasts. AgNPs effectively inhibited the growth of a planktonic S. mutans clinical isolate and killed established S. mutans biofilms, which suggests that AgNPs could be used for prevention and treatment of dental caries. Further research and development are necessary to translate this technology into therapeutic and preventive strategies. - Highlights: • Biological activities of silver nanoparticles for dental caries purposes • Antimicrobial activity of AgNPs on planktonic cell was size and concentration dependent. • Reduction in the S. mutans biofilm formation was statistically significant. • AgNPs at high concentrations showed a cytotoxic effect upon human dermal fibroblasts. • AgNPs could be used for prevention and treatment of dental caries.

  11. Determination of silver in personal care nanoproducts and effects on dermal exposure

    Energy Technology Data Exchange (ETDEWEB)

    Wasukan, Nootcharin [National Science and Technology Development Agency (NSTDA), National Nanotechnology Center (Thailand); Srisung, Sujittra, E-mail: sujittras@g.swu.ac.th [Srinakharinwirot University, Department of Chemistry, Faculty of Science (Thailand); Kulthong, Kornphimol; Boonrungsiman, Suwimon; Maniratanachote, Rawiwan, E-mail: rawiwan@nanotec.or.th [National Science and Technology Development Agency (NSTDA), National Nanotechnology Center (Thailand)

    2015-11-15

    Silver (Ag) is one of the widely used nanomaterials in cosmetics, personal care, and household products. This research aimed to investigate the Ag concentration contained in 20 commercial nanoproducts using a simple and reliable procedure. The exposure and adverse effects of a single topical application of Ag on the skin were also evaluated. Herein, we demonstrated that the technique of wet acid digestion, extraction and detection of Ag with graphite furnace absorption spectrometry were effective for any and all nanoproduct matrices. The Ag morphology was characterized by scanning and transmission electron microscopy equipped with energy-dispersive x-ray spectroscopy. Penetration of Ag was evaluated using a polyethersulfone (PES) membrane through a Franz cell and reconstructed human epidermis (RhE) tissue. A skin irritation test was performed on RhE, an acceptable in vitro model which was in compliance with OECD test guideline 439. The results showed that the initial Ag concentration in the tested nanoproducts ranged between 0.0058 and 94 µg/g. However, particulate Ag was only found in two products, both of a liquid formulation. Silver penetration through a PES membrane (0.12–53 % by weight) was weakly correlated with the initial Ag concentration in each sample, but more so to the product formulation. The liquid products demonstrated the highest percent of average Ag penetration, followed by the semi-solid and solid formulations, respectively. In contrast, neither any Ag diffusion from these products into the RhE tissue nor any irritation or toxicity was detected. This study suggests a screening method to evaluate the Ag level in products and their potential adverse effects on the skin that could be incorporated as a part of risk assessment for nanotechnology products.

  12. Determination of silver in personal care nanoproducts and effects on dermal exposure

    International Nuclear Information System (INIS)

    Wasukan, Nootcharin; Srisung, Sujittra; Kulthong, Kornphimol; Boonrungsiman, Suwimon; Maniratanachote, Rawiwan

    2015-01-01

    Silver (Ag) is one of the widely used nanomaterials in cosmetics, personal care, and household products. This research aimed to investigate the Ag concentration contained in 20 commercial nanoproducts using a simple and reliable procedure. The exposure and adverse effects of a single topical application of Ag on the skin were also evaluated. Herein, we demonstrated that the technique of wet acid digestion, extraction and detection of Ag with graphite furnace absorption spectrometry were effective for any and all nanoproduct matrices. The Ag morphology was characterized by scanning and transmission electron microscopy equipped with energy-dispersive x-ray spectroscopy. Penetration of Ag was evaluated using a polyethersulfone (PES) membrane through a Franz cell and reconstructed human epidermis (RhE) tissue. A skin irritation test was performed on RhE, an acceptable in vitro model which was in compliance with OECD test guideline 439. The results showed that the initial Ag concentration in the tested nanoproducts ranged between 0.0058 and 94 µg/g. However, particulate Ag was only found in two products, both of a liquid formulation. Silver penetration through a PES membrane (0.12–53 % by weight) was weakly correlated with the initial Ag concentration in each sample, but more so to the product formulation. The liquid products demonstrated the highest percent of average Ag penetration, followed by the semi-solid and solid formulations, respectively. In contrast, neither any Ag diffusion from these products into the RhE tissue nor any irritation or toxicity was detected. This study suggests a screening method to evaluate the Ag level in products and their potential adverse effects on the skin that could be incorporated as a part of risk assessment for nanotechnology products

  13. Silver nanoparticles with antimicrobial activities against Streptococcus mutans and their cytotoxic effect

    International Nuclear Information System (INIS)

    Pérez-Díaz, Mario Alberto; Boegli, Laura; James, Garth; Velasquillo, Cristina; Sánchez-Sánchez, Roberto; Martínez-Martínez, Rita-Elizabeth; Martínez-Castañón, Gabriel Alejandro; Martinez-Gutierrez, Fidel

    2015-01-01

    Microbial resistance represents a challenge for the scientific community to develop new bioactive compounds. The goal of this research was to evaluate the antimicrobial activity of silver nanoparticles (AgNPs) against a clinical isolate of Streptococcus mutans, antibiofilm activity against mature S. mutans biofilms and the compatibility with human fibroblasts. The antimicrobial activity of AgNPs against the planktonic clinical isolate was size and concentration dependent, with smaller AgNPs having a lower minimum inhibitory concentration. A reduction of 2.3 log in the number of colony-forming units of S. mutans was observed when biofilms grown in a CDC reactor were exposed to 100 ppm of AgNPs of 9.5 ± 1.1 nm. However, AgNPs at high concentrations (> 10 ppm) showed a cytotoxic effect upon human dermal fibroblasts. AgNPs effectively inhibited the growth of a planktonic S. mutans clinical isolate and killed established S. mutans biofilms, which suggests that AgNPs could be used for prevention and treatment of dental caries. Further research and development are necessary to translate this technology into therapeutic and preventive strategies. - Highlights: • Biological activities of silver nanoparticles for dental caries purposes • Antimicrobial activity of AgNPs on planktonic cell was size and concentration dependent. • Reduction in the S. mutans biofilm formation was statistically significant. • AgNPs at high concentrations showed a cytotoxic effect upon human dermal fibroblasts. • AgNPs could be used for prevention and treatment of dental caries

  14. Effect of halideions on the surface-enhanced Raman spectroscopy of methylene blue for borohydride-reduced silver colloid

    International Nuclear Information System (INIS)

    Dong Xiao; Gu Huaimin; Liu Fang

    2011-01-01

    The surface enhanced Raman scattering (SERS) spectrum of methylene blue (MB) was studied when adding a range of halideions to borohydride-reduced silver colloid. The halideions such as chloride, bromide and iodide were added as aggregating agents to study the effects of halideions on SERS spectroscopy of MB and observe which halideion gives the greatest enhancement for borohydride-reduced silver colloids. The SERS spectra of MB were also detected over a wide range of concentrations of halideions to find the optimum concentration of halideions for SERS enhancement. From the results of this study, the intensity of SERS signal of MB was enhanced significantly when adding halideions to the colloid. Among the three kinds of halideions, chloride gives the greatest enhancement on SERS signal. The enhancement factors for MB with optimal concentration of chloride, bromide and iodide are 3.44x10 4 , 2.04x10 4 , and 1.0x10 4 , respectively. The differences of the SERS spectra of MB when adding different kinds and concentrations of halideions to the colloid may be attributed to the both effects of extent of aggregation of the colloid and the modification of silver surface chemistry. The purpose of this study is to further investigate the effect of halideions on borohydride-reduced silver colloid and to make the experimental conditions suitable for detecting some analytes in high efficiency on rational principles.

  15. Enhancing light reflective properties on ITO glass by plasmonic effect of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Dezhong Zhang

    Full Text Available The preparation of well-defined silver (Ag nanoparticle arrays is reported in this paper. Ag nanoparticles are electrodeposited on Indium tin oxide (ITO coated glass substrates at 30 °C. The size, shape and periodicity of the Ag nanoparticle arrays are well-controlled. We study the effect of particle size and interparticle distance on reflection enhancement. The sample at the deposition potential of −0.2 V for an electrodeposition time of 3600 s exhibits an enhancement of 28% in weighted reflection in contrast with bare ITO glass. This study reports the high reflection of Ag nanoparticle arrays by electrodeposition method might be application to large-scale photovoltaic devices.

  16. Modulating the Optoelectronic Properties of Silver Nanowires Films: Effect of Capping Agent and Deposition Technique.

    Science.gov (United States)

    Lopez-Diaz, D; Merino, C; Velázquez, M M

    2015-11-11

    Silver nanowires 90 nm in diameter and 9 µm in length have been synthesized using different capping agents: polyvinyl pyrrolidone (PVP) and alkyl thiol of different chain lengths. The nanowire structure is not influenced by the displacement of PVP by alkyl thiols, although alkyl thiols modify the lateral aggregation of nanowires. We examined the effect of the capping agent and the deposition method on the optical and electrical properties of films prepared by Spray and the Langmuir-Schaefer methodologies. Our results revealed that nanowires capped with PVP and C8-thiol present the best optoelectronic properties. By using different deposition techniques and by modifying the nanowire surface density, we can modulate the optoelectronic properties of films. This strategy allows obtaining films with the optoelectronic properties required to manufacture touch screens and electromagnetic shielding.

  17. Modulating the Optoelectronic Properties of Silver Nanowires Films: Effect of Capping Agent and Deposition Technique

    Directory of Open Access Journals (Sweden)

    D. Lopez-Diaz

    2015-11-01

    Full Text Available Silver nanowires 90 nm in diameter and 9 µm in length have been synthesized using different capping agents: polyvinyl pyrrolidone (PVP and alkyl thiol of different chain lengths. The nanowire structure is not influenced by the displacement of PVP by alkyl thiols, although alkyl thiols modify the lateral aggregation of nanowires. We examined the effect of the capping agent and the deposition method on the optical and electrical properties of films prepared by Spray and the Langmuir-Schaefer methodologies. Our results revealed that nanowires capped with PVP and C8-thiol present the best optoelectronic properties. By using different deposition techniques and by modifying the nanowire surface density, we can modulate the optoelectronic properties of films. This strategy allows obtaining films with the optoelectronic properties required to manufacture touch screens and electromagnetic shielding.

  18. 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...

  19. Silver-Doping Effects and Photostructural Transformation in Evaporated AS2S3 Thin Films.

    Science.gov (United States)

    1982-02-16

    of evaporated silver halide films. The details of the preparation of evaporated films of silver halides are reported by Junod at. al. (41 ) The...1980). 40. M.S. Chang, N.D. Hwang, J.T. Chen, Extended Abstr. Electrochem. Soc., 80-1, 692, (1980). 41. P. Junod , N. MHediger, B. Kilchoy. R. Steiger

  20. Uptake and effect of highly fluorescent silver nanoclusters on Scenedesmus obliquus.

    Science.gov (United States)

    Zhang, Li; He, Yiliang; Goswami, Nirmal; Xie, Jianping; Zhang, Bo; Tao, Xianji

    2016-06-01

    The release of silver nanoparticles (Ag NPs) in aquatic environment has caused wide public concern about their effects on living organisms (e.g., algae). However, how these small NPs exert cytotoxicity in the living organisms has always been under heated debate. In this study, the uptake and toxicity effects of strongly red-emitting fluorescent silver nanoclusters (r-Ag NCs) exposed to the green algae Scenedesmus obliquus was investigated. Upon exposure to pure r-Ag NCs and r-Ag NCs containing l-cysteine, the algae growth inhibition test showed that Ag(+) ions released from r-Ag NCs played an important role in the toxicity of r-Ag NCs along with the toxicity of intact r-Ag NCs. Furthermore, no signals of intracellular reactive oxygen species (ROS) were observed indicating that r-Ag NCs or released Ag(+) ions - mediated growth inhibition of algae cells was independent of ROS production. Transmission electron microscopy (TEM) and laser scanning confocal microscopy (LSCM) were employed to study cellular uptake and cytotoxicity. Furthermore, analysis of differential expressed gene demonstrated that r-Ag NCs as well as the released Ag(+) ions can simultaneously exist inside the algae cells, and inhibit the transcriptomic process of genes by their "joint-toxicity" mechanism. Taken together, our study provides a new insight into the molecular mechanisms of r-Ag NCs and Ag(+) ions exposure to the aquatic organism and can be applied to early diagnosis of ecologic risk mediated by others metal-based NPs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Effects of polymer surface energy on morphology and properties of silver nanowire fabricated via nanoimprint and E-beam evaporation

    Science.gov (United States)

    Zhao, Zhi-Jun; Hwang, Soon Hyoung; Jeon, Sohee; Jung, Joo-Yun; Lee, Jihye; Choi, Dae-Geun; Choi, Jun-Hyuk; Park, Sang-Hu; Jeong, Jun-Ho

    2017-10-01

    In this paper, we demonstrate that use of different nanoimprint resins as a polymer pattern has a significant effect on the morphology of silver (Ag) nanowires deposited via an E-beam evaporator. RM-311 and Ormo-stamp resins are chosen as a polymer pattern to form a line with dimensions of width (100 nm) × space (100 nm) × height (120 nm) by using nanoimprint lithography (NIL). Their contact angles are then measured to evaluate their surface energies. In order to compare the properties of the Ag nanowires deposited on the various polymer patterns with different surface energies, hydrophobic surface treatment of the polymer pattern surface is implemented using self-assembled monolayers. In addition, gold and aluminum nanowires are fabricated for comparison with the Ag nanowires, with the differences in the nanowire morphologies being determined by the different atomic properties. The monocrystalline and polycrystalline structures of the various Ag nanowire formations are observed using transmission electron microscopy. In addition, the melting temperatures and optical properties of four kinds of Ag nanowire morphologies deposited on various polymer patterns are evaluated using a hot plate and an ultraviolet-visible (UV-vis) spectrometer, respectively. The results indicate that the morphology of the Ag nanowire determines the melting temperature and the transmission. We believe that these findings will greatly aid the development of NIL, along with physical evaporation and chemical deposition techniques, and will be widely employed in optics, biology, and surface wettability applications.

  2. Effect of incorporation of silver nanoparticles in PEDOT:PSS layer on performance of organic solar cell

    Science.gov (United States)

    Singh, Joginder; Nirwal, Varun Singh; Bhatnagar, P. K.; Peta, Koteswara Rao

    2018-05-01

    Solution processable organic solar cells have attracted significant interest in scientific community due to their easy processability, flexibility and eco friendly fabrication. In these organic solar cells structure, PEDOT:PSS layer has major importance as it used as hole transporting layer. In the present work, we have analyzed the effect of incorporation of silver nanoparticles (AgNPs) in PEDOT:PSS layer for P3HT:PCBM based organic solar cells. The presence of Ag nanoparticles in PEDOT:PSS film is confirmed by atomic force microscopy (AFM) images. It has been observed that PEDOT:PSS layer with AgNPs has ˜5.4% more transmittance than PEDOT:PSS layer in most of the visible region, which helps in reaching more light on active layer. Finally, solar cell with structure ITO/PEDOT:PSS:AgNPs/Al is fabricated and J-V characteristics are plotted under illumination. It is observed that there is a significant (˜10%) enhancement in short circuit current and slight increment in open circuit voltage with addition of AgNPs in PEDOT:PSS layer. The calculated value of power conversion efficiency (PCE) of fabricated device without AgNPs in PEDOT:PSS was 1.67%, which increased to 2.02% after addition of AgNPs in PEDOT:PSS layer.

  3. 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)

  4. Class II glass ionomer/silver cermet restorations and their effect on interproximal growth of mutans streptococci.

    Science.gov (United States)

    Berg, J H; Farrell, J E; Brown, L R

    1990-02-01

    The release of fluoride from glass ionomer materials is one of the most important features of this newly implemented material, and the remineralization effects of this phenomenon have been documented (Hicks and Silverstone 1986). This paper examines the effects of glass ionomer/silver cermet restorations on the plaque levels of interproximal mutans streptococci. Fifteen patients with Class II lesions in primary molars were selected for study. Interproximal plaque samples were obtained from each of the lesion sites and from one caries-free site approximal to a primary molar. One lesion was restored with composite resin to serve as a treated control to the glass ionomer/silver cermet (Ketac Silver, ESPE/Premier Sales Corp., Norristown, Pennsylvania) test site. A sound (unaltered) interproximal site served as the untreated control site. Plaque samples were collected before and at one week, one month, and three months post-treatment. Samples were serially diluted to enable colony counts of mutans streptococci. One week post-treatment counts showed that the glass ionomer/silver cermet restorations significantly reduced (P less than 0.05) the approximal plaque levels of mutans streptococci. Conversely, the untreated and treated control sites did not exhibit reductions in approximal plaque levels of mutans streptococci. These results indicate that glass ionomer restorations may be inhibitory to the growth of mutans streptococci in dental plaque approximal to this restorative material in the primary dentition.

  5. 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

  6. In vitro screening of silver nanoparticles and ionic silver using neural networks yields differential effects on spontaneous activity and pharmacological responses.

    Science.gov (United States)

    Silver nanoparticles (AgNPs) are used in a wide range of consumer and medical products because of their antimicrobial and antifungal properties. Numerous studies have demonstrated that silver can translocate to distal organs following exposure to AgNPs. Therefore, it is essential...

  7. 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.

  8. 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.

  9. Highly effective field-effect mobility amorphous InGaZnO TFT mediated by directional silver nanowire arrays.

    Science.gov (United States)

    Liu, Hung-Chuan; Lai, Yi-Chun; Lai, Chih-Chung; Wu, Bing-Shu; Zan, Hsiao-Wen; Yu, Peichen; Chueh, Yu-Lun; Tsai, Chuang-Chuang

    2015-01-14

    In this work, we demonstrate sputtered amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a record high effective field-effect mobility of 174 cm(2)/V s by incorporating silver nanowire (AgNW) arrays to channel electron transport. Compared to the reference counterpart without nanowires, the over 5-fold enhancement in the effective field-effect mobility exhibits clear dependence on the orientation as well as the surface coverage ratio of silver nanowires. Detailed material and device analyses reveal that during the room-temperature IGZO sputtering indium and oxygen diffuse into the nanowire matrix while the nanowire morphology and good contact between IGZO and nanowires are maintained. The unchanged morphology and good interfacial contact lead to high mobility and air-ambient-stable characteristics up to 3 months. Neither hysteresis nor degraded bias stress reliability is observed. The proposed AgNW-mediated a-IGZO TFTs are promising for development of large-scale, flexible, transparent electronics.

  10. Synergistic effects of iodine and silver ions co-implanted in 6H–SiC

    International Nuclear Information System (INIS)

    Kuhudzai, R.J.; Malherbe, J.B.; Hlatshwayo, T.T.; Berg, N.G. van der; Devaraj, A.; Zhu, Z.; Nandasiri, M.

    2015-01-01

    Motivated by the aim of understanding the release of fission products through the SiC coating of fuel kernels in modern high temperature nuclear reactors, a fundamental investigation is conducted to understand the synergistic effects of implanted silver (Ag) and iodine (I) in 6H–SiC. The implantation of the individual species, as well as the co-implantation of 360 keV ions of I and Ag at room temperature in 6H–SiC and their subsequent annealing behaviour has been investigated by Secondary Ion Mass Spectrometry (SIMS), Atom Probe Tomography (APT) and X-ray Photoelectron Spectroscopy (XPS). SIMS and APT measurements indicated the presence of Ag in the co-implanted samples after annealing at 1500 °C for 30 h in sharp contrast to the samples implanted with Ag only. In samples implanted with Ag only, complete loss of the implanted Ag was observed. However, for I only implanted samples, some iodine was retained. APT of annealed co-implanted 6H–SiC showed clear spatial association of Ag and I clusters in SiC, which can be attributed to the observed I assisted retention of Ag after annealing. Such detailed studies will be necessary to identify the fundamental mechanism of fission products migration through SiC coatings. - Highlights: • Co-implantation of Ag and I ions in 6H–SiC was performed. • Clear spatial association of Ag and I clusters observed after annealing. • Complete loss of Ag after high temperature annealing of silver only sample. • Iodine was retained in iodine only sample after high temperature annealing. • Iodine was found to play a role in the retention of Ag in the co-implanted samples.

  11. 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...

  12. 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

  13. The effect of silver nitrate, chloroformic garlic extract and normal saline in induction of sclerosing cholangitis in rabbits

    International Nuclear Information System (INIS)

    Hosseni, Seyed V.; Mohebzadeh, J.; Mehrabani, D.; Amini, M.; Kumar, Perikala V.; Bagheri, Mohammad H.; Sadjjadi, Seyed M.; Amini, A.

    2008-01-01

    Objective was to the effects of 0.5% silver nitrate, 20% chloroformic garlic extract and 0.9% normal saline in induction of sclerosing cholangitis in the bile ducts of rabbits. During a 6-months period from April to September 2006 in Shiraz University Laboratory Animal Research Center, we selected 3 equal groups of rabbits. We injected 0.5% silver nitrate, 20% chloroformic garlic extract and 0.9% normal saline into the bile ducts of each group. The animals were euthanized and autopsied after 4 months and the liver and bile ducts were removed and studied histopathologically. Cholangiography was undertaken to evaluate the presence and extent of any sclerosing cholangitis. Animals showed sclerosing cholangitis in silver nitrate group (7 [58%]), one (8%) in chloroformic garlic extract group and one (7%) in normal saline group. The difference between silver nitrate and chloroformic garlic extract groups were statistically significant and similar results were noticed between chloroformic garlic extract and normal saline groups. Twenty percent of chloroformic garlic extract had fewer complications such as sclerosing cholangitis, compared to other materials. (author)

  14. Effect of gold and silver nanoparticles on the morpho-functional state of the epididymis and prostate gland in rats

    Directory of Open Access Journals (Sweden)

    V. Y. Kalynovskyi

    2016-09-01

    Full Text Available Metals are widely used in modern medicine: iron, copper, zinc, vanadium, titanium – all of them are vital for treatment of different diseases. Recently a new field of medical technology has emerged, which focuses on the biomedical application of metallic nanoparticles, with a particular interest in a gold and silver-based materials. These structures are already used for photothermal anticancer therapy, drug delivery, bioimaging, radiosensitizers and as drugs themselves. Despite the wide usage of nanoparticles, we still don’t know much about the toxicity of nanomaterials. Nanotoxicological studies are mainly carried out in vitro, but in vivo effects are still elusive. Hence, we focused on the reproductive toxicity of gold and silver nanosized particles. Spherical 10–15 nm gold and silver nanoparticles were synthesized through the reduction of sodium tetrachloroaurate (III and silver nitrate respectively with ascorbic acid in the presence of sodium polyphosphate as a coating and stabilizing agent. Next, these particles were administered intraperitoneally to the young and adult animals (1- and 6-months old respectively at 1 mg/kg dose for 10 days. As quantitative markers of functional activity, we used the diameter of epididymal tubules, height and the nuclear cross-section of epididymal epitheliocytes and relative volume of the prostatic epithelium. We showed that intraperitoneal administrations of nanogold to young animals caused no significant histological changes, although we found a decrease in the nuclear cross-sectional area of epididymal epitheliocytes. At the same time, nanogold caused more morphometric changes in adult animals. Similar results were obtained from the nanosilver groups. Silver nanoparticles caused an observable decrease of sperm quantity in the lumen of epididymal tubules with a simultaneous increase in the number of extraepididymal cells in young animals. Morphometric parameters of the epididymis and prostate also

  15. The effect of silver thickness on the enhancement of polymer based SERS substrates

    International Nuclear Information System (INIS)

    Schneidewind, H; Weber, K; Zeisberger, M; Hübner, U; Dellith, A; Cialla-May, D; Mattheis, R; Popp, J

    2014-01-01

    We investigated silver-covered polymer based nanogratings as substrates for surface-enhanced Raman spectroscopy (SERS), in particular with respect to the thickness of the plasmonically active silver film. In order to obtain accurate geometrical input data for the simulation process, we inspected cross sections of the gratings prepared by breaking at cryogenic temperature. We noticed a strong dependence of the simulation results on geometrical variations of the structures. Measurements revealed that an increasing silver film thickness on top of the nanogratings leads to a blue shift of the plasmonic resonance, as predicted by numerical simulations, as well as to an increased field enhancement for an excitation at 488 nm. We found a clear deviation of the experimental data compared to the simulated results for very thin silver films due to an island-like growth at a silver thickness below 20 nm. In order to investigate the SERS activity. we carried out measurements with crystal violet as a model analyte at an excitation wavelength of 488 nm. The SERS enhancement increases up to a silver thickness of about 30 nm, whereas it remains nearly constant for thicker silver films. (paper)

  16. 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

  17. Silver Nanoparticles and Studies on Using in Poultry Nutrition

    Directory of Open Access Journals (Sweden)

    Mehmet Akif Özcan

    2015-02-01

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

  18. Special Resins for Stereolithography: In Situ Generation of Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Gabriele Taormina

    2018-02-01

    Full Text Available The limited availability of materials with special properties represents one of the main limitations to a wider application of polymer-based additive manufacturing technologies. Filled resins are usually not suitable for vat photo-polymerization techniques such as stereolithography (SLA or digital light processing (DLP due to a strong increment of viscosity derived from the presence of rigid particles within the reactive suspension. In the present paper, the possibility to in situ generate silver nanoparticles (AgNPs starting from a homogeneous liquid system containing a well dispersed silver salt, which is subsequently reduced to metallic silver during stereolithographic process, is reported. The simultaneous photo-induced cross-linking of the acrylic resin produces a filled thermoset resin with thermal-mechanical properties significantly enhanced with respect to the unfilled resin, even at very low AgNPs concentrations. With this approach, the use of silver salts having carbon-carbon double bonds, such as silver acrylate and silver methacrylate, allows the formation of a nanocomposite structure in which the release of by-products is minimized due to the active role of all the reactive components in the three dimensional (3D-printing processes. The synergy, between this nano-technology and the geometrical freedom offered by SLA, could open up a wide spectrum of potential applications for such a material, for example in the field of food packaging and medical and healthcare sectors, considering the well-known antimicrobial effects of silver nanoparticles.

  19. Silver enhances antibiotic activity against gram-negative bacteria.

    Science.gov (United States)

    Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

    2013-06-19

    A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

  20. Effects of silver nanoparticles to soil invertebrates: Oxidative stress biomarkers in Eisenia fetida

    International Nuclear Information System (INIS)

    Gomes, Susana I.L.; Hansen, Ditte; Scott-Fordsmand, Janeck J.; Amorim, Mónica J.B.

    2015-01-01

    Silver nanoparticles (Ag-NPs) are among the most produced NPs worldwide having several applications in consumer products. Ag-NPs are known to cause oxidative stress in several organisms and cell lines, however comparatively less information is available regarding their effects on soil living invertebrates. The purpose of this study was to investigate if Ag-NPs cause oxidative stress on soil invertebrates. The model soil species Eisenia fetida was used. Our results showed that total glutathione (TG) is the first mechanism triggered by Ag-NPs, followed by glutathione peroxidase (GPx) and glutathione reductase (GR), however oxidative damage was observed for higher doses and exposure time (increased lipid peroxidation, LPO). AgNO 3 exposure caused impairment in GPx and glutathione-S-transferase (GST), probably as result of the higher bioavailability of Ag in the salt-form. The current results indicate that effects are partly caused by Ag ions released from Ag-NPs, but specific particle effects cannot be excluded. - Highlights: • Oxidative stress of Ag-NPs and AgNO 3 was assessed in Eisenia fetida. • Both Ag forms induced oxidative damage (LPO) via different mechanisms. • Ag-NPs activated total glutathione, followed by GPx and GR. • AgNO 3 impaired GPx and GST. • Overall results indicated effects from Ag ionization and NPs specific effects. - Oxidative stress to Ag in Eisenia fetida occurs via different mechanisms for Ag nanoparticles and AgNO 3

  1. Effect of silver nanoparticles on photo-induced reorientation of azo groups in polymer films

    International Nuclear Information System (INIS)

    Zhou Jingli; Yang Jianjun; Sun Youyi; Zhang Douguo; Shen Jing; Zhang Qijin; Wang Keyi

    2007-01-01

    A series of polymer films containing azo groups and silver nanoparticles were prepared. Photo-induced reorientation of the film was conducted under irradiation of polarized light with wavelength at 365 nm, 442 nm and 532 nm, respectively. The influence of the concentration of dopant silver on the reorientation of the azo groups was studied. An enhancement of about 50% for the reorientation rate and about 70% for the reorientation amplitude was achieved. From a comparison of the enhancement obtained by irradiating with three different light sources, it was realized that the mechanism for enhancement of reorientation of azo groups is due to plasmon resonance of silver nanoparticles doped in the polymer films

  2. Differential neurotoxic effects of silver nanoparticles: A review with special emphasis on potential biomarkers

    Directory of Open Access Journals (Sweden)

    M. Safari

    2016-04-01

    Full Text Available Silver Nanoparticles (AgNPs have gained considerable interests during the last decade due to their excellent antimicrobial activities. Despite their extensive use, the potential toxicity of these nanoparticles and possible mechanisms by which they may induce adverse reactions have not received sufficient attention and no specific biomarker exist to describe and quantify their toxic effects. Nanoparticles, depending on their physicochemical characteristics and compositions, can interact with vital organs such as the brain and induce toxic effects. A specific concern is that any contact with AgNPs independent of the route of administration is thought to result in significant systemic uptake, internal exposure of sensitive organs, especially in the central nervous system (CNS and different toxic responses. There are considerable evidences that AgNPs can disrupt the Blood-Brain Barrier (BBB and induce subsequent brain edema formation. Therefore, it is essential to understand the differential effects of AgNPs on brain cell with especial emphasis on the possible mechanisms of action. Recently, biomarkers are increasingly used as surrogate indicators of toxic responses in biological monitoring due to the inaccessibility of target organs. Moreover, as the most nanoscale contaminants occur at low concentrations, physiological biomarkers may be better indicators of potential impact of nanomaterials than traditional toxicity testing. This review aims to investigate the effects of AgNPs on CNS targets of toxicity and clarify the role of existing biomarkers especially the role of dopamine levels as a potential biomarker of Ag-NPs neurotoxicity.

  3. Effect of silver content on mechanical and electric properties of HTSC YBaCuO/Ag ceramics

    International Nuclear Information System (INIS)

    Markov, L.K.; Orlova, T.S.; Peschanskaya, N.N.; Smirnov, B.I.; Stepanov, Yu.P.; Shpejzman, V.V.

    2003-01-01

    It is shown that addition of 3-5 wt. % silver to YBaCuO superconducting ceramics leads to noticeable increase on its microplasticity and strength. Temperature spectra of microplastic deformation rates for YbaCuO/Ag ceramics with 0, 1.6, 2.9, 4.2 and 7.6 wt. % silver are obtained. Spectra structure as well as a bond of one of the peaks with superconducting transition is discussed. Peculiarities of the volt-ampere characteristics (VAC) of samples cooled in the magnetic field are considered. It is shown that the position of VAC ascending branch depends on VAC start point which may be used for fixing two or more stable positions of the memory cell on the basis of high-temperature superconductors [ru

  4. Effects of some polymeric additives on the cocrystallization of caffeine

    Science.gov (United States)

    Chung, Jihae; Kim, Il Won

    2011-11-01

    Effects of polymeric additives on the model cocrystallization were examined. The model cocrystal was made from caffeine and oxalic acid, and poly(ethylene glycol) (PEG), poly( L-lactide) (PLLA), poly(ɛ-caprolactone) (PCL), and poly(acrylic acid) (PAA) were the additives. The cocrystals were formed as millimeter-sized crystals without additives, and they became microcrystals with PLLA and PCL, and nanocrystals with PAA. XRD and IR revealed that the cocrystal structure was unchanged despite the strong effects of the additives on the crystal morphology, although some decrease in crystallinity was observed with PAA as confirmed by DSC. The DSC study also showed that the cocrystal melted and recrystallized to form α-caffeine upon heating. The present study verified that the polymeric additives can be utilized to modulate the size and morphology of the cocrystals without interfering the intermolecular interactions essential to the integrity of the cocrystal structures.

  5. POEM: Identifying joint additive effects on regulatory circuits

    Directory of Open Access Journals (Sweden)

    Maya eBotzman

    2016-04-01

    Full Text Available Motivation: Expression Quantitative Trait Locus (eQTL mapping tackles the problem of identifying variation in DNA sequence that have an effect on the transcriptional regulatory network. Major computational efforts are aimed at characterizing the joint effects of several eQTLs acting in concert to govern the expression of the same genes. Yet, progress towards a comprehensive prediction of such joint effects is limited. For example, existing eQTL methods commonly discover interacting loci affecting the expression levels of a module of co-regulated genes. Such ‘modularization’ approaches, however, are focused on epistatic relations and thus have limited utility for the case of additive (non-epistatic effects.Results: Here we present POEM (Pairwise effect On Expression Modules, a methodology for identifying pairwise eQTL effects on gene modules. POEM is specifically designed to achieve high performance in the case of additive joint effects. We applied POEM to transcription profiles measured in bone marrow-derived dendritic cells across a population of genotyped mice. Our study reveals widespread additive, trans-acting pairwise effects on gene modules, characterizes their organizational principles, and highlights high-order interconnections between modules within the immune signaling network. These analyses elucidate the central role of additive pairwise effect in regulatory circuits, and provide computational tools for future investigations into the interplay between eQTLs.Availability: The software described in this article is available at csgi.tau.ac.il/POEM/.

  6. Effect of silver nanoparticles on Pseudomonas putida biofilms at different stages of maturity

    Energy Technology Data Exchange (ETDEWEB)

    Thuptimdang, Pumis, E-mail: pumis.th@gmail.com [International Program in Hazardous Substance and Environmental Management, Graduate School, Chulalongkorn University, Bangkok 10330 (Thailand); Center of Excellence on Hazardous Substance Management, Bangkok 10330 (Thailand); Limpiyakorn, Tawan, E-mail: tawan.l@chula.ac.th [Center of Excellence on Hazardous Substance Management, Bangkok 10330 (Thailand); Department of Environmental Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Research Unit Control of Emerging Micropollutants in Environment, Chulalongkorn University, Bangkok 10330 (Thailand); McEvoy, John, E-mail: john.mcevoy@ndsu.edu [Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58108 (United States); Prüß, Birgit M., E-mail: birgit.pruess@ndsu.edu [Department of Veterinary and Microbiological Sciences, North Dakota State University, Fargo, ND 58108 (United States); Khan, Eakalak, E-mail: eakalak.khan@ndsu.edu [Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND 58108 (United States)

    2015-06-15

    Highlights: • Biofilm stages in static batch conditions were similar to dynamic conditions. • Expression of csgA gene increased earlier than alg8 gene in biofilm maturation. • AgNPs had higher effect on less mature biofilms. • Removal of extracellular polymeric substance made biofilms susceptible to AgNPs. - Abstract: This study determined the effect of silver nanoparticles (AgNPs) on Pseudomonas putida KT2440 biofilms at different stages of maturity. Three biofilm stages (1–3, representing early to late stages of development) were identified from bacterial adenosine triphosphate (ATP) activity under static (96-well plate) and dynamic conditions (Center for Disease Control and Prevention biofilm reactor). Extracellular polymeric substance (EPS) levels, measured using crystal violet and total carbohydrate assays, and expression of the EPS-associated genes, csgA and alg8, supported the conclusion that biofilms at later stages were older than those at earlier stages. More mature biofilms (stages 2 and 3) showed little to no reduction in ATP activity following exposure to AgNPs. In contrast, the same treatment reduced ATP activity by more than 90% in the less mature stage 1 biofilms. Regardless of maturity, biofilms with EPS stripped off were more susceptible to AgNPs than controls with intact EPS, demonstrating that EPS is critical for biofilm tolerance of AgNPs. The findings from this study show that stage of maturity is an important factor to consider when studying effect of AgNPs on biofilms.

  7. Effect of silver nanoparticles on Pseudomonas putida biofilms at different stages of maturity

    International Nuclear Information System (INIS)

    Thuptimdang, Pumis; Limpiyakorn, Tawan; McEvoy, John; Prüß, Birgit M.; Khan, Eakalak

    2015-01-01

    Highlights: • Biofilm stages in static batch conditions were similar to dynamic conditions. • Expression of csgA gene increased earlier than alg8 gene in biofilm maturation. • AgNPs had higher effect on less mature biofilms. • Removal of extracellular polymeric substance made biofilms susceptible to AgNPs. - Abstract: This study determined the effect of silver nanoparticles (AgNPs) on Pseudomonas putida KT2440 biofilms at different stages of maturity. Three biofilm stages (1–3, representing early to late stages of development) were identified from bacterial adenosine triphosphate (ATP) activity under static (96-well plate) and dynamic conditions (Center for Disease Control and Prevention biofilm reactor). Extracellular polymeric substance (EPS) levels, measured using crystal violet and total carbohydrate assays, and expression of the EPS-associated genes, csgA and alg8, supported the conclusion that biofilms at later stages were older than those at earlier stages. More mature biofilms (stages 2 and 3) showed little to no reduction in ATP activity following exposure to AgNPs. In contrast, the same treatment reduced ATP activity by more than 90% in the less mature stage 1 biofilms. Regardless of maturity, biofilms with EPS stripped off were more susceptible to AgNPs than controls with intact EPS, demonstrating that EPS is critical for biofilm tolerance of AgNPs. The findings from this study show that stage of maturity is an important factor to consider when studying effect of AgNPs on biofilms

  8. The Effect of a Silver Nanoparticle Polysaccharide System on Streptococcal and Saliva-Derived Biofilms

    Directory of Open Access Journals (Sweden)

    Luigina Cellini

    2013-06-01

    Full Text Available In this work, we studied the antimicrobial properties of a nanocomposite system based on a lactose-substituted chitosan and silver nanoparticles: Chitlac-nAg. Twofold serial dilutions of the colloidal Chitlac-nAg solution were both tested on Streptococcus mitis, Streptococcus mutans, and Streptococcus oralis planktonic phase and biofilm growth mode as well as on saliva samples. The minimum inhibitory and bactericidal concentrations of Chitlac-nAg were evaluated together with its effect on sessile cell viability, as well as both on biofilm formation and on preformed biofilm. In respect to the planktonic bacteria, Chitlac-nAg showed an inhibitory/bactericidal effect against all streptococcal strains at 0.1% (v/v, except for S. mitis ATCC 6249 that was inhibited at one step less. On preformed biofilm, Chitlac-nAg at a value of 0.2%, was able to inhibit the bacterial growth on the supernatant phase as well as on the mature biofilm. For S. mitis ATCC 6249, the biofilm inhibitory concentration of Chitlac-nAg was 0.1%. At sub-inhibitory concentrations, the Streptococcal strains adhesion capability on a polystyrene surface showed a general reduction following a concentration-dependent-way; a similar effect was obtained for the metabolic biofilm activity. From these results, Chitlac-nAg seems to be a promising antibacterial and antibiofilm agent able to hinder plaque formation.

  9. Biopolymers Regulate Silver Nanoparticle under Microwave Irradiation for Effective Antibacterial and Antibiofilm Activities.

    Directory of Open Access Journals (Sweden)

    Palaniyandi Velusamy

    Full Text Available In the current study, facile synthesis of carboxymethyl cellulose (CMC and sodium alginate capped silver nanoparticles (AgNPs was examined using microwave radiation and aniline as a reducing agent. The biopolymer matrix embedded nanoparticles were synthesized under various experimental conditions using different concentrations of biopolymer (0.5, 1, 1.5, 2%, volumes of reducing agent (50, 100, 150 μL, and duration of heat treatment (30 s to 240 s. The synthesized nanoparticles were analyzed by scanning electron microscopy, UV-Vis spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy for identification of AgNPs synthesis, crystal nature, shape, size, and type of capping action. In addition, the significant antibacterial efficacy and antibiofilm activity of biopolymer capped AgNPs were demonstrated against different bacterial strains, Staphylococcus aureus MTCC 740 and Escherichia coli MTCC 9492. These results confirmed the potential for production of biopolymer capped AgNPs grown under microwave irradiation, which can be used for industrial and biomedical applications.

  10. The Effect of Different Additives and Medium on the Bioleaching of Molybdenite for Cu and Mo Extraction Using Mix Mesophilic Microorganism

    Directory of Open Access Journals (Sweden)

    Hadi Abdollahia

    2013-06-01

    Full Text Available Bioleaching processes for extraction of Cu and Mo from molybdenite cons. are more environmentally friendly and consume less energy than conventional technologies, yet less economically efficient. One necessary step towards arriving at a cost-effective bioleaching process is using appropriate methodology to optimize pertinent factors in such processes. To this end, the present study employed Response Surface Methodology to optimize important factors in a molybdenite bioleaching process by mix mesophilic microorganism using shake flasks. The effect of change in the levels of molybdenite concentration, pyrite and silver ion concentration as additives - in the range 3-9%, 1-5%, and 0-1.2gr/l, respectively - on the rate of Cu and Mo bioleaching was studied using a Central Composite Design. The results showed a statistically significant effect of silver ion and molybdenite concentration, and to a lesser pyrite concentration, on the rate of bioleaching of Cu and Mo. Further, different mediums and additives were evaluated for copper and molybdenum extraction from molybdenite concentrate in bioleaching process. Small amounts of silver (100mgr/l AgSO4 dramatically accelerated the copper dissolution process. Addition of FeS2 and sulfur with ferrous sulfate accelerated the acidification and raised the oxidation-reduction potential of solution (medium with an inoculation of 15% (v/v of active and adapted indigenous mesophilic bacteria, thus resulting in an overall increase in Mo dissolution efficiency.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-06-15

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

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

    International Nuclear Information System (INIS)

    Aguilar-Méndez, Miguel A.; San Martín-Martínez, Eduardo; Ortega-Arroyo, Lesli; Cobián-Portillo, Georgina; Sánchez-Espíndola, Esther

    2011-01-01

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

  13. Synergistic antibacterial effect of silver and ebselen against multidrug-resistant Gram-negative bacterial infections.

    Science.gov (United States)

    Zou, Lili; Lu, Jun; Wang, Jun; Ren, Xiaoyuan; Zhang, Lanlan; Gao, Yu; Rottenberg, Martin E; Holmgren, Arne

    2017-08-01

    Multidrug-resistant (MDR) Gram-negative bacteria account for a majority of fatal infections, and development of new antibiotic principles and drugs is therefore of outstanding importance. Here, we report that five most clinically difficult-to-treat MDR Gram-negative bacteria are highly sensitive to a synergistic combination of silver and ebselen. In contrast, silver has no synergistic toxicity with ebselen on mammalian cells. The silver and ebselen combination causes a rapid depletion of glutathione and inhibition of the thioredoxin system in bacteria. Silver ions were identified as strong inhibitors of Escherichia coli thioredoxin and thioredoxin reductase, which are required for ribonucleotide reductase and DNA synthesis and defense against oxidative stress. The bactericidal efficacy of silver and ebselen was further verified in the treatment of mild and acute MDR E. coli peritonitis in mice. These results demonstrate that thiol-dependent redox systems in bacteria can be targeted in the design of new antibacterial drugs. The silver and ebselen combination offers a proof of concept in targeting essential bacterial systems and might be developed for novel efficient treatments against MDR Gram-negative bacterial infections. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  14. Direct and Maternal Additive Effects on Rabbit Growth and Linear ...

    African Journals Online (AJOL)

    Growth and linear body measurements of rabbits which consisted of 17 ew Zealand White (ZW), 19 Chinchilla (CH), 29 ZW x CH and 33 CH x ZW kittens were compared. The aim of the experiment was to evaluate the crossbreeding effects (i.e direct and maternal additive effect) for growth (individual body weight, IBW) and ...

  15. Antileishmanial effect of silver nanoparticles and their enhanced antiparasitic activity under ultraviolet light

    Directory of Open Access Journals (Sweden)

    Allahverdiyev AM

    2011-11-01

    Full Text Available Adil M Allahverdiyev1, Emrah Sefik Abamor1, Malahat Bagirova1, Cem B Ustundag2, Cengiz Kaya2, Figen Kaya2, Miriam Rafailovich3 1Department of Bioengineering; 2Department of Metallurgical and Materials Engineering, Yildiz Technical University, Esenler, Istanbul, Turkey; 3Department of Materials Science and Engineering, Stony Brook University, Stony Brook, NY, USA Abstract: Leishmaniasis is a protozoan vector-borne disease and is one of the biggest health problems of the world. Antileishmanial drugs have disadvantages such as toxicity and the recent development of resistance. One of the best-known mechanisms of the antibacterial effects of silver nanoparticles (Ag-NPs is the production of reactive oxygen species to which Leishmania parasites are very sensitive. So far no information about the effects of Ag-NPs on Leishmania tropica parasites, the causative agent of leishmaniasis, exists in the literature. The aim of this study was to investigate the effects of Ag-NPs on biological parameters of L. tropica such as morphology, metabolic activity, proliferation, infectivity, and survival in host cells, in vitro. Consequently, parasite morphology and infectivity were impaired in comparison with the control. Also, enhanced effects of Ag-NPs were demonstrated on the morphology and infectivity of parasites under ultraviolet (UV light. Ag-NPs demonstrated significant antileishmanial effects by inhibiting the proliferation and metabolic activity of promastigotes by 1.5- to threefold, respectively, in the dark, and 2- to 6.5-fold, respectively, under UV light. Of note, Ag-NPs inhibited the survival of amastigotes in host cells, and this effect was more significant in the presence of UV light. Thus, for the first time the antileishmanial effects of Ag-NPs on L. tropica parasites were demonstrated along with the enhanced antimicrobial activity of Ag-NPs under UV light. Determination of the antileishmanial effects of Ag-NPs is very important for the further

  16. Antiproliferative effect of silver nanoparticles synthesized using amla on Hep2 cell line

    Institute of Scientific and Technical Information of China (English)

    Fathima Stanley Rosarin; Vadivel Arulmozhi; Samuthira Nagarajan; Sankaran Mirunalini

    2013-01-01

    Objective: To synthesize silver nanoparticles by amla extract, screen the cytotoxic, oxidative stress and apoptotic effect of silver nanoparticles (AgNPs) on Hep2 cell line (laryngeal carcinoma cells) in vitro, and to compare the effect of Phyllanthus emblica (P. emblica) (amla) with AgNPs synthesized by amla and 5-FU. Methods: AgNPs was synthesized by P. emblica (aqueous extract) and nanoparticles were characterized UV-Vis spec, the presence of biomoloecules of amla capped in AgNPs was found by FT-IR analysis, shape and size were examined by SEM and DLS. Cytotoxicity of experimental drugs was tested to find IC50 value. ROS generation in cells have been measured by DCFH-DA staining, AO-EtBr, Rhodamine-123 staining and DNA fragmentation were performed to assess apoptotic cell death, mitochondrial membrane potential and apoptotic DNA damage, respectively. Oxidative stress was analyzed by measuring lipid peroxides and antioxidants level to understand the cancer cell death by pro-oxidant mechanism.Results:PE-AgNPs was synthesized and confirmed through kinetic behavior of NPs. The shape of PE-AgNPs was spherical and cubic since it was agglomerated, and the nanoparticle surface was complicated. Average particle size distribution of PE-AgNPs was found to be 188 nm. Potent biomolecules of P. emblica such as polyphenols were capped with AgNPs and reduced its toxicity. In cytotoxicity assay the concentration in which the maximum number of cell death was 60 μg/mL and 50 μg/mL for P. emblica (alone) and AgNPs, respectively and IC50 values were fixed as 30 μg/mL and 20 μg/mL. ROS generation, apoptotic morphological changes, mitochondrial depolarization, DNA damage and oxidative stress was observed as more in AgNPs treated cells than in P. emblica (30 μg/mL) (alone) treated cells and 5-FU treated cells gave similar result.Conclusions:The results suggest that the AgNPs are capped with biomolecules of amla enhanced cytotoxicity in laryngeal cancer cells through oxidative

  17. Rapid green synthesis of silver nanoparticles and nanorods using Piper nigrum extract

    International Nuclear Information System (INIS)

    Mohapatra, Bandita; Kuriakose, Sini; Mohapatra, Satyabrata

    2015-01-01

    Highlights: • Silver nanorods were synthesized by photoreduction using Piper nigrum extract. • The morphological and structural properties were studied by XRD and AFM. • Silver nanoparticles were formed at lower AgNO 3 concentration. • Increase in AgNO 3 concentration resulted in formation of silver nanorods. - Abstract: We report sun light driven rapid green synthesis of stable aqueous dispersions of silver nanoparticles and nanorods at room temperature using photoreduction of silver ions with Piper nigrum extract. Silver nanoparticles were formed within 3 min of sun light irradiation following addition of Piper nigrum extract to the AgNO 3 solution. The effects of AgNO 3 concentration and irradiation time on the formation and plasmonic properties of biosynthesized silver nanoparticles were studied using UV–visible absorption spectroscopy. The morphology and structure of silver nanoparticles were well characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The size of Ag nanoparticles increased with increase in irradiation time, leading to the formation of anisotropic nanostructures. Increasing the AgNO 3 concentration resulted in the formation of Ag nanorods. UV–visible absorption studies revealed the presence of surface plasmon resonance (SPR) peaks which red shift and broaden with increasing AgNO 3 concentration. We have demonstrated a facile, energy efficient and rapid green synthetic route to synthesize stable aqueous dispersions of silver nanoparticles and nanorods

  18. Rapid green synthesis of silver nanoparticles and nanorods using Piper nigrum extract

    Energy Technology Data Exchange (ETDEWEB)

    Mohapatra, Bandita [Multifunctional Nanomaterials Laboratory, School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi 110078 (India); Kuriakose, Sini [Multifunctional Nanomaterials Laboratory, School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi 110078 (India); School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi 110078 (India); Mohapatra, Satyabrata, E-mail: smiuac@gmail.com [Multifunctional Nanomaterials Laboratory, School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi 110078 (India); School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi 110078 (India)

    2015-07-15

    Highlights: • Silver nanorods were synthesized by photoreduction using Piper nigrum extract. • The morphological and structural properties were studied by XRD and AFM. • Silver nanoparticles were formed at lower AgNO{sub 3} concentration. • Increase in AgNO{sub 3} concentration resulted in formation of silver nanorods. - Abstract: We report sun light driven rapid green synthesis of stable aqueous dispersions of silver nanoparticles and nanorods at room temperature using photoreduction of silver ions with Piper nigrum extract. Silver nanoparticles were formed within 3 min of sun light irradiation following addition of Piper nigrum extract to the AgNO{sub 3} solution. The effects of AgNO{sub 3} concentration and irradiation time on the formation and plasmonic properties of biosynthesized silver nanoparticles were studied using UV–visible absorption spectroscopy. The morphology and structure of silver nanoparticles were well characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The size of Ag nanoparticles increased with increase in irradiation time, leading to the formation of anisotropic nanostructures. Increasing the AgNO{sub 3} concentration resulted in the formation of Ag nanorods. UV–visible absorption studies revealed the presence of surface plasmon resonance (SPR) peaks which red shift and broaden with increasing AgNO{sub 3} concentration. We have demonstrated a facile, energy efficient and rapid green synthetic route to synthesize stable aqueous dispersions of silver nanoparticles and nanorods.

  19. Green synthesis of monodisperse silver nanoparticles using hydroxy propyl methyl cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Chunfa; Zhang, Xianglin, E-mail: hust_zxl@mail.hust.edu.cn; Cai, Hao

    2014-01-15

    Graphical abstract: -- Highlights: • Synthesis of silver nanoparticles using hydroxy propyl methyl cellulose is reported. • HPMC and glucose are used as capping agent and reducing agent respectively. • It is the first time to use HPMC for synthesis of silver nanoparticles. • The small, spherical and well-dispersed particle is observed in the range of 3–17 nm. • The green method can be extended to other noble metals. -- Abstract: A simple and environmentally friendly method for the synthesis of highly stable and small sized silver nanoparticles with narrow distribution from 3 nm to 17 nm is reported. Silver nitrate, hydroxy propyl methyl cellulose (HPMC) and glucose, were used as silver precursor, capping agents and reducing agents respectively. The formation of silver nanoparticles was observed by change of color from colorless to wine red. The silver nanoparticles were characterized by transmission electron microscopy (TEM), UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The results demonstrated that the obtained metallic nanoparticles were single crystalline silver nanoparticles capped with HPMC. The effects of the reaction time, reaction temperature and the concentration of silver ion and reducing agents on the particle size were investigated. A possible formation mechanism was proposed. The method may be extended to other noble metal for other technological applications such as additional medicinal, industrial applications.

  20. Green synthesis of monodisperse silver nanoparticles using hydroxy propyl methyl cellulose

    International Nuclear Information System (INIS)

    Dong, Chunfa; Zhang, Xianglin; Cai, Hao

    2014-01-01

    Graphical abstract: -- Highlights: • Synthesis of silver nanoparticles using hydroxy propyl methyl cellulose is reported. • HPMC and glucose are used as capping agent and reducing agent respectively. • It is the first time to use HPMC for synthesis of silver nanoparticles. • The small, spherical and well-dispersed particle is observed in the range of 3–17 nm. • The green method can be extended to other noble metals. -- Abstract: A simple and environmentally friendly method for the synthesis of highly stable and small sized silver nanoparticles with narrow distribution from 3 nm to 17 nm is reported. Silver nitrate, hydroxy propyl methyl cellulose (HPMC) and glucose, were used as silver precursor, capping agents and reducing agents respectively. The formation of silver nanoparticles was observed by change of color from colorless to wine red. The silver nanoparticles were characterized by transmission electron microscopy (TEM), UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The results demonstrated that the obtained metallic nanoparticles were single crystalline silver nanoparticles capped with HPMC. The effects of the reaction time, reaction temperature and the concentration of silver ion and reducing agents on the particle size were investigated. A possible formation mechanism was proposed. The method may be extended to other noble metal for other technological applications such as additional medicinal, industrial applications

  1. Low molecular weight chitosan-coated silver nanoparticles are effective for the treatment of MRSA-infected wounds

    Directory of Open Access Journals (Sweden)

    Peng Y

    2017-01-01

    Full Text Available Yinbo Peng,1 Chenlu Song,1 Chuanfeng Yang,1 Qige Guo,1 Min Yao1,2 1Department of Burns and Plastic Surgery, Shanghai Ninth People’s Hospital, Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China; 2Department of Dermatology, Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, Boston, MA, USA Abstract: Silver nanoparticles (AgNPs are being widely applied as topical wound materials; however, accumulated deposition of silver in the liver, spleen, and other main organs may lead to organ damage and dysfunction. We report here that low molecular weight chitosan-coated silver nanoparticles (LMWC-AgNPs are effective against methicillin-resistant Staphylococcus aureus (MRSA, have better biocompatibility, and have lower body absorption characteristics when compared with polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs and silver nanoparticles without surface stabilizer (uncoated-AgNPs in a dorsal MRSA wound infection mouse model. LMWC-AgNPs were synthesized by reducing silver nitrate with low molecular weight chitosan as a stabilizer and reducing agent, while PVP-AgNPs were synthesized using polyvinylpyrrolidone as a stabilizer and ethanol as a reducing agent. AgNPs with different surface stabilizers were identified by UV-visible absorption spectrometry, and particle size was determined by transmission electron microscopy. UV-visible absorption spectra of LMWC-AgNPs, PVP-AgNPs and uncoated-AgNPs were similar and their sizes were in the range of 10–30 nm. In vitro experiments showed that the three types of AgNPs had similar MRSA-killing effects, with obvious effect at 4 µg/mL and 100% effect at 8 µg/mL. Bacteriostatic annulus experiments also showed that all the three types of AgNPs had similar antibacterial inhibitory effect at 10 µg/mL. Cell counting kit-8 assay and Hoechst/propidium iodide (PI staining showed that LMWC-AgNPs were

  2. Effects of silver nanoparticles on nitrification and associated nitrous oxide production in aquatic environments.

    Science.gov (United States)

    Zheng, Yanling; Hou, Lijun; Liu, Min; Newell, Silvia E; Yin, Guoyu; Yu, Chendi; Zhang, Hongli; Li, Xiaofei; Gao, Dengzhou; Gao, Juan; Wang, Rong; Liu, Cheng

    2017-08-01

    Silver nanoparticles (AgNPs) are the most common materials in nanotechnology-based consumer products globally. Because of the wide application of AgNPs, their potential environmental impact is currently a highly topical focus of concern. Nitrification is one of the processes in the nitrogen cycle most susceptible to AgNPs but the specific effects of AgNPs on nitrification in aquatic environments are not well understood. We report the influence of AgNPs on nitrification and associated nitrous oxide (N 2 O) production in estuarine sediments. AgNPs inhibited nitrification rates, which decreased exponentially with increasing AgNP concentrations. The response of nitrifier N 2 O production to AgNPs exhibited low-dose stimulation (production could be enhanced by >100% at low doses of AgNPs. This result was confirmed by metatranscriptome studies showing up-regulation of nitric oxide reductase (norQ) gene expression in the low-dose treatment. Isotopomer analysis revealed that hydroxylamine oxidation was the main N 2 O production pathway, and its contribution to N 2 O emission was enhanced when exposed to low-dose AgNPs. This study highlights the molecular underpinnings of the effects of AgNPs on nitrification activity and demonstrates that the release of AgNPs into the environment should be controlled because they interfere with nitrifying communities and stimulate N 2 O emission.

  3. Silver nanoparticles with antimicrobial activities against Streptococcus mutans and their cytotoxic effect.

    Science.gov (United States)

    Pérez-Díaz, Mario Alberto; Boegli, Laura; James, Garth; Velasquillo, Cristina; Sánchez-Sánchez, Roberto; Martínez-Martínez, Rita-Elizabeth; Martínez-Castañón, Gabriel Alejandro; Martinez-Gutierrez, Fidel

    2015-10-01

    Microbial resistance represents a challenge for the scientific community to develop new bioactive compounds. The goal of this research was to evaluate the antimicrobial activity of silver nanoparticles (AgNPs) against a clinical isolate of Streptococcus mutans, antibiofilm activity against mature S. mutans biofilms and the compatibility with human fibroblasts. The antimicrobial activity of AgNPs against the planktonic clinical isolate was size and concentration dependent, with smaller AgNPs having a lower minimum inhibitory concentration. A reduction of 2.3 log in the number of colony-forming units of S. mutans was observed when biofilms grown in a CDC reactor were exposed to 100 ppm of AgNPs of 9.5±1.1 nm. However, AgNPs at high concentrations (>10 ppm) showed a cytotoxic effect upon human dermal fibroblasts. AgNPs effectively inhibited the growth of a planktonic S. mutans clinical isolate and killed established S. mutans biofilms, which suggests that AgNPs could be used for prevention and treatment of dental caries. Further research and development are necessary to translate this technology into therapeutic and preventive strategies. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Effects of Humic and Fulvic Acids on Silver Nanoparticle Stability, Dissolution, and Toxicity

    Science.gov (United States)

    Gunsolus, Ian L.; Mousavi, Maral P. S.; Hussein, Kadir; Bühlmann, Philippe; Haynes, Christy L.

    2015-01-01

    The colloidal stability of silver nanoparticles (AgNPs) in natural aquatic environments influences their transport and environmental persistence, while their dissolution to Ag+ influences their toxicity to organisms. Here, we characterize the colloidal stability, dissolution behavior, and toxicity of two industrially relevant classes of AgNPs (i.e., AgNPs stabilized by citrate or polyvinylpyrrolidone) after exposure to natural organic matter (NOM, i.e., Suwannee River Humic and Fulvic Acid Standards and Pony Lake Fulvic Acid Reference). We show that NOM interaction with the nanoparticle surface depends on (i) the NOM’s chemical composition, where sulfur- and nitrogen-rich NOM more significantly increases colloidal stability, and (ii) the affinity of the capping agent for the AgNP surface, where nanoparticles with loosely bound capping agents are more effectively stabilized by NOM. Adsorption of NOM is shown to have little effect on AgNP dissolution under most experimental conditions, the exception being when the NOM is rich in sulfur and nitrogen. Similarly, the toxicity of AgNPs to a bacterial model (Shewanella oneidensis MR-1) decreases most significantly in the presence of sulfur- and nitrogen-rich NOM. Our data suggest that the rate of AgNP aggregation and dissolution in aquatic environments containing NOM will depend on the chemical composition of the NOM, and that the toxicity of AgNPs to aquatic microorganisms is controlled primarily by the extent of nanoparticle dissolution. PMID:26047330

  5. The Effect of Charge at the Surface of Silver Nanoparticles on Antimicrobial Activity against Gram-Positive and Gram-Negative Bacteria: A Preliminary Study

    International Nuclear Information System (INIS)

    Abbaszadegan, A.; Ghahramani, Y.; Nabavizadeh, M.; Gholami, A.; Hemmateenejad, I.; Dorostkar, S.; Sharghi, H.

    2014-01-01

    The bactericidal efficiency of various positively and negatively charged silver nanoparticles has been extensively evaluated in literature, but there is no report on efficacy of neutrally charged silver nanoparticles. The goal of this study is to evaluate the role of electrical charge at the surface of silver nanoparticles on antibacterial activity against a panel of microorganisms. Three different silver nanoparticles were synthesized by different methods, providing three different electrical surface charges (positive, neutral, and negative). The antibacterial activity of these nanoparticles was tested against gram-positive (i.e., Staphylococcus aureus, Streptococcus mutans, and Streptococcus pyogenes) and gram-negative (i.e., Escherichia coli and Proteus vulgaris) bacteria. Well diffusion and micro-dilution tests were used to evaluate the bactericidal activity of the nanoparticles. According to the obtained results, the positively-charged silver nanoparticles showed the highest bactericidal activity against all microorganisms tested. The negatively charged silver nanoparticles had the least and the neutral nanoparticles had intermediate antibacterial activity. The most resistant bacteria were Proteus vulgaris. We found that the surface charge of the silver nanoparticles was a significant factor affecting bactericidal activity on these surfaces. Although the positively charged nanoparticles showed the highest level of effectiveness against the organisms tested, the neutrally charged particles were also potent against most bacterial species.

  6. Genomic Model with Correlation Between Additive and Dominance Effects.

    Science.gov (United States)

    Xiang, Tao; Christensen, Ole Fredslund; Vitezica, Zulma Gladis; Legarra, Andres

    2018-05-09

    Dominance genetic effects are rarely included in pedigree-based genetic evaluation. With the availability of single nucleotide polymorphism markers and the development of genomic evaluation, estimates of dominance genetic effects have become feasible using genomic best linear unbiased prediction (GBLUP). Usually, studies involving additive and dominance genetic effects ignore possible relationships between them. It has been often suggested that the magnitude of functional additive and dominance effects at the quantitative trait loci are related, but there is no existing GBLUP-like approach accounting for such correlation. Wellmann and Bennewitz showed two ways of considering directional relationships between additive and dominance effects, which they estimated in a Bayesian framework. However, these relationships cannot be fitted at the level of individuals instead of loci in a mixed model and are not compatible with standard animal or plant breeding software. This comes from a fundamental ambiguity in assigning the reference allele at a given locus. We show that, if there has been selection, assigning the most frequent as the reference allele orients the correlation between functional additive and dominance effects. As a consequence, the most frequent reference allele is expected to have a positive value. We also demonstrate that selection creates negative covariance between genotypic additive and dominance genetic values. For parameter estimation, it is possible to use a combined additive and dominance relationship matrix computed from marker genotypes, and to use standard restricted maximum likelihood (REML) algorithms based on an equivalent model. Through a simulation study, we show that such correlations can easily be estimated by mixed model software and accuracy of prediction for genetic values is slightly improved if such correlations are used in GBLUP. However, a model assuming uncorrelated effects and fitting orthogonal breeding values and dominant

  7. 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

  8. The effect of baking conditions on the effective contact areas of screen-printed silver layer on silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Tietun Sun; Jianmin Miao; Rongming Lin; Yongqing Fu [Nanyang Technological Univ., Micromachines Lab., Singapore (Singapore)

    2005-01-01

    In this paper, Ag-based paste was screen-printed on polished as well as on textured p-type (100) single crystalline silicon wafers. Three types of baking processes were studied: the tube furnace, the belt furnace and the hot plate baking. The effective contact areas of Ag/Si system were measured with a novel method, namely metal insulator semiconductor structure measurement. The results show that after baking on the hot plate at 400 deg C for 5 min, the size and number of pores in the Ag film layer as well as at the interface between silver layer and silicon decreases significantly, the effective contact area also increases about 20%, particularly on the textured silicon substrate. (Author)

  9. The effect of baking conditions on the effective contact areas of screen-printed silver layer on silicon substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Tietun; Miao, Jianmin; Lin, Rongming; Fu, Yongqing [Micromachines Laboratory, School of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2005-01-01

    In this paper, Ag-based paste was screen-printed on the polished as well as on the textured p-type (100) single crystalline silicon wafers. Three types of baking processes were studied: the tube furnace, the belt furnace and the hot plate baking. The effective contact areas of Ag/Si system were measured with a novel method, namely metal insulator semiconductor structure measurement. The results show that after baking on the hot plate at 400{sup o}C for 5min, the size and number of pores in the Ag film layer as well as at the interface between silver layer and silicon decreases significantly, the effective contact area also increases about 20%, particularly on the textured silicon substrate.

  10. Silver effect on the structure of SiO2-CaO-P2O5 ternary system

    International Nuclear Information System (INIS)

    Vulpoi, Adriana; Baia, Lucian; Simon, Simion; Simon, Viorica

    2012-01-01

    In this study are reported results obtained from the structural, morphological and textural investigations of 56SiO 2 ∙(40-x)CaO·4P 2 O 5 ·xAg 2 O system, where 0 ≤ x ≤ 10 mol%. The samples obtained by sol–gel method were annealed and then characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), thermal gravimetric analysis (TGA), vibrational spectroscopy (Raman, FTIR), N 2 -adsorption measurements, and transmission electron microscopy (TEM). XRD patterns of the investigated samples exhibit tricalcium phosphate (TCP) nanostructured phase and show the existence of metallic silver as dispersed phase. The presence of apatite-like phase is underlined by the recorded Raman and especially FT-IR spectra. TEM pictures indicate the presence of silver nanoparticles of almost spherical shapes and various sizes inside the matrix, depending on the Ag 2 O content. Regarding the textural properties, it was observed both a decrease of the specific surface area as well as a progressive change of the mesoporous characteristics with the silver addition, the latter behavior recommending the potential use of these samples for applications, where the morphology control is required.

  11. Effect of Different Mediated Agents on Morphology and Crystallinity of Synthesized Silver Nanowires Prepared by Polyol Process

    Directory of Open Access Journals (Sweden)

    Mohammad Taghi Satoungar

    2016-01-01

    Full Text Available Synthesis and characterization of multiple crystalline silver nanowires (NWs with uniform diameters were carried out by using 1,2-propandiol and ethylene glycol (EG as comediated solvents and FeCl3 as mediated agent in the presence of poly(vinyl pyrrolidone (PVP. Experimental data and structural characterizations revealed that AgNWs have evolved from the multiple crystalline seeds initially generated by reduction of AgNO3 with EG and 1,2-propandiol followed by reducing Fe(III to Fe(II which in turn reacts with and removes adsorbed atomic oxygen from the surfaces of silver seeds. In addition, uniform silver nanowires were obtained by using FeCl2 and AlCl3 as mediated agents in EG solution. Field emission scanning electron microscopy (FESEM and transmission electron microscopy (TEM showed uniform nanowires in both diameter and length. UV-Vis spectra showed adsorption peaks confirming the formation of nanowires. X-ray diffraction (XRD patterns displayed the final product with high crystallinity and purity. In this study, a growth mechanism for forming AgNWs was proposed and a comparison between different mediated agents was carried out.

  12. Effect of bismuth and silver on the corrosion behavior of Sn-9Zn alloy in NaCl 3 wt.% solution

    Energy Technology Data Exchange (ETDEWEB)

    Ahmido, A. [Laboratory of Chimie Physique General, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); Laboratory of Spectroscopy Infra Rouge, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); Sabbar, A. [Laboratory of Chimie Physique General, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); Zouihri, H.; Dakhsi, K. [UATRS, CNRST, Angle Allal Fassi, FAR, BP 8027, Hay Riad, Rabat (Morocco); Guedira, F. [Laboratory of Chimie Physique General, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); Serghini-Idrissi, M. [Laboratory of Spectroscopy Infra Rouge, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco); El Hajjaji, S., E-mail: selhajjaji@hotmail.com [Laboratory of Spectroscopy Infra Rouge, Faculty of Sciences, University Med V Agdal, Av. Ibn Battouta, B.P. 1014, M-10000 Rabat (Morocco)

    2011-08-15

    Highlights: > Sn-9Zn-xAg-yBi as alternative for Sn-Pb solder. > Effect of silver (Ag) and bismuth (Bi) on the corrosion resistance of Sn-9Zn alloy in NaCl 3 wt%. > Bi and Ag lead to the increase of corrosion rate. > EDS and XRD analyses confirmed the oxide of zinc (ZnO and Zn5(OH){sub 8}Cl{sub 2}H{sub 2}O) as the major corrosion product. - Abstract: The effect of silver (Ag) and bismuth (Bi) on the corrosion resistance of Sn-9Zn alloy in NaCl 3 wt.% solution was investigated using electrochemical techniques. The results showed that the addition of Bi and Ag lead to the increase of corrosion rate and the corrosion potential E{sub corr} is shifted towards less noble values. After immersion, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive of spectroscopy (EDS) analysis of the corroded alloy surface revealed the nature of corrosion products. EDS and XRD analyses confirmed the oxide of zinc (ZnO and Zn{sub 5}(OH){sub 8}Cl{sub 2}H{sub 2}O) as the major corrosion product formed on the outer surface of in the tested three solder alloys.

  13. VITAMINE C EFFECT ON SILVER NITRATE INDUCED METHEMOGLOBINEMIA:ANIMAL STUDY

    Directory of Open Access Journals (Sweden)

    M.A RAJABI

    2001-09-01

    Full Text Available Introduction. Methemoglobinemia is a condition characterized by increased quantities of hemoglobin in which the iron of heme is oxidized to the ferric(Fe3+ form. Methemoglobin is useless as an oxygen carrier and thus causes a varying degree of cyanosis. The condition may arise as a result of a genetic defect in red blood cell metabolism or hemoglobin structure, or it may be acquired following exposure to various axidant drugs or toxins. The most common cause of methemoglobinemia, as in this clinical case, is ingestion of or exposure of skin or mucous membranes to oxidizing agents (such as anesthetics and silver nitrate. Methods. In an experimental animal study, 30 rabbits with the same weight and sex are devided in two groups (A and B.-Vitamine C is administered to group B (200 mg/kg intraperitoneal. One houre after that, laparotomy was done. Then silver nitrate was injected intraperitoneal (1000 mg/kg in both groups. Blood samples were examined 30 and 60 minutes after injection. Results. Methemoglobin before and after intervention in group A was 0.38±0.13, 1.63±0.02 (30 min and 2.21 ± 0.4 (60 min percent respectively. Methemoglobin before and after intervention in group B was 0.39±0.13, 0.82 ± 0.19 (30 min and 0.41 ± 0.1.7 (60 min percent, respectively. Methemoglobin concentration was greater in group A in 30th and 60th minute after intervention (P < 0.0l Discussion. Ascorbic acid penetrate the erythrocyte membrane. Under physiological conditions ascorbic acid induced methemoglobin reduction is far less important than reduction by the NADH dependent methemoglobin reductase system. In methemoglobinemic conditions caused by toxic effects or by congenital methemoglobin reductase deficiency treatment with ascorbic acid is possible. However, critically increased methemoglobin content of the blood higher than 30% makes therapy with methylene blue necessary. So, vitamine C is recommended for methemoglobinemia therapy.

  14. Morphology and oxygen incorporation effect on antimicrobial activity of silver thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rebelo, Rita, E-mail: ritarebelo@det.uminho.pt [2C2T, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); GRF-CFUM, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); CEB, Center for Biological Engineering, LIBRO—Laboratório de Biofilmes Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-335 Braga (Portugal); Manninen, N.K. [GRF-CFUM, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); SEG-CEMUC, University of Coimbra, 3030-788 Coimbra (Portugal); Fialho, Luísa [GRF-CFUM, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); Henriques, Mariana [CEB, Center for Biological Engineering, LIBRO—Laboratório de Biofilmes Rosário Oliveira, University of Minho, Campus de Gualtar, 4710-335 Braga (Portugal); Carvalho, Sandra [GRF-CFUM, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); SEG-CEMUC, University of Coimbra, 3030-788 Coimbra (Portugal)

    2016-05-15

    Highlights: • Ag and Ag{sub x}O thin films were deposited by non-reactive and reactive pulsed DC magnetron sputtering. • Coatings were characterized chemically, physically and structurally. • In order to verify the antibacterial behavior of the coatings, halo inhibition zone tests were realized for Staphylococcus epidermidis and Staphylococcus aureus. • Ag{sub x}O coating presented antibacterial behavior. - Abstract: Ag and Ag{sub x}O thin films were deposited by non-reactive and reactive pulsed DC magnetron sputtering, respectively, with the final propose of functionalizing the SS316L substrate with antibacterial properties. The coatings were characterized chemically, physically and structurally. The coatings nanostructure was assessed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while the coatings morphology was determined by scanning electron microscopy (SEM). The XRD and XPS analyses suggested that Ag thin film is composed by metallic Ag, which crystallizes in fcc-Ag phase, while the Ag{sub x}O thin film showed both metallic Ag and Ag−O bonds, which crystalize in fcc-Ag and silver oxide phases. The SEM results revealed that Ag thin film formed a continuous layer, while Ag{sub x}O layer was composed of islands with hundreds of nanometers surrounded by small nanoparticles with tens of nanometers. The surface wettability and surface tension parameters were determined by contact angle measurements, being found that Ag and Ag{sub x}O surfaces showed very similar behavior, with all the surfaces showing a hydrophobic character. In order to verify the antibacterial behavior of the coatings, halo inhibition zone tests were realized for Staphylococcus epidermidis and Staphylococcus aureus. Ag coatings did not show antibacterial behavior, contrarily to Ag{sub x}O coating, which presented antibacterial properties against the studied bacteria. The presence of silver oxide phase along with the development of different morphology was

  15. In situ generation of silver nanoparticles in poly(vinyl alcohol)/poly(acrylic acid) polymer membranes in the absence of reducing agent and their effect on pervaporation of a water/acetic acid mixture

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhard, Shvshankar; Kwon, Yong Sung; Moon, MyungJun; Shon, Min Young [Dept. of Industrial Chemistry, Pukyong National University, Busan (Korea, Republic of); Park, You In; Nam, Seung Eun [Center for membranes, Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of)

    2016-12-15

    The in situ generation of silver nanoparticles in a poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) polymer matrix in the absence of any additional reducing agent is reported and tends to the membrane fabrication using solution-casting. Its effect on the separation of a water/acetic acid mixture by pervaporation is described. The results of UV spectroscopy, scanning electron microscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy analyses showed that the silver nanoparticles were successfully prepared and well dispersed in the polymer matrix. The increased hydrophilicity of the PVA/PAA membrane due to the presence of silver nanoparticles was confirmed by Fourier transform infrared spectroscopy, contact angle measurements, and membrane absorption studies. Pervaporation data for composite membranes showed a three-fold increase in the flux value, while the initially decreased separation factor subsequently showed a constant value. Overall, the pervaporation data suggested that the presence of silver nanoparticles benefited the dehydration process.

  16. In situ generation of silver nanoparticles in poly(vinyl alcohol)/poly(acrylic acid) polymer membranes in the absence of reducing agent and their effect on pervaporation of a water/acetic acid mixture

    International Nuclear Information System (INIS)

    Chaudhard, Shvshankar; Kwon, Yong Sung; Moon, MyungJun; Shon, Min Young; Park, You In; Nam, Seung Eun

    2016-01-01

    The in situ generation of silver nanoparticles in a poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) polymer matrix in the absence of any additional reducing agent is reported and tends to the membrane fabrication using solution-casting. Its effect on the separation of a water/acetic acid mixture by pervaporation is described. The results of UV spectroscopy, scanning electron microscopy, and scanning electron microscopy/energy-dispersive X-ray spectroscopy analyses showed that the silver nanoparticles were successfully prepared and well dispersed in the polymer matrix. The increased hydrophilicity of the PVA/PAA membrane due to the presence of silver nanoparticles was confirmed by Fourier transform infrared spectroscopy, contact angle measurements, and membrane absorption studies. Pervaporation data for composite membranes showed a three-fold increase in the flux value, while the initially decreased separation factor subsequently showed a constant value. Overall, the pervaporation data suggested that the presence of silver nanoparticles benefited the dehydration process

  17. An additional memory effect in mass spectrometry for BF3

    International Nuclear Information System (INIS)

    Hoshino, Kiichi; Satooka, Sakae

    1978-01-01

    It is considered that the memory effect appears in a metallic gas inlet of a mass spectrometer for measurement with samples of BF 3 is classified into two kinds, one is essential memory effect which is caused by an action between the surface of metal and BF 3 , and the other is additional memory effect which is caused by viscous liquid produced by reaction among water, BF 3 and metals. The additional memory effect is caused by stain on the inner surface of the gas inlet. Air is introduced into the sample bottle joint at each time for change of sample bottle. Moisture in the air is adsorbed on inner surfaces of the joint and piping made of metal, and combined with BF 3 which is introduced, and then viscous compound is produced by dissolution of the metal into the compound made from H 2 O and BF 3 . The vapour pressure of the viscous compound is not sufficient low, and so the compound propagates from the sample bottle joint to the whole of the gas inlet at each time of opening and closing of valves of the gas inlet. The coated film of the viscous compound with adsorption and release of Bf 3 is a cause of the additional memory effect. If the stain of the inner surface of the gas inlet grows up, the additional memory effect becomes more intense compared with the essential memory effect, and the measured values are not converged. To remove the additional memory effect, it is desirable to introduce the sample BF 3 after the moisture intruded into the piping by the exchange of sample bottles is removed sufficiently by introduction of F 2 or ClF 3 . (auth.)

  18. In situ production of silver nanoparticles for high sensitive detection of ascorbic acid via inner filter effect

    Energy Technology Data Exchange (ETDEWEB)

    Rezaei, B., E-mail: rezaeimeister@gmail.com; Shahshahanipour, M.; Ensafi, Ali A.

    2017-02-01

    In the present research, a sensitive biosensing method was proposed for the detection of trace amounts of ascorbic acid (AA). Herein, colloidal silver nanoparticles (SNPs) were successfully in-situ produced by chemical reduction of silver ion in the presence of AA, as a reducing agent. The one-pot in-situ produced silver nanoparticles were characterized by UV–vis, dynamic light scattering (DLS), zeta potential and transmission electron microscopic (TEM). SNPs act as a strong fluorescence quencher for the CdTe quantum dots via an inner filter effect (IFE). Since the absorption band of SNPs entirely covered both emission and excitation bands of QDs. Therefore, the decreasing in the fluorescence signal depends on the AA concentration in the linear range of 0.2–88.0 ng mL{sup −1} and with a detection limit of 0.02 ng mL{sup −1}. Relative standard deviations of 2.3% and 2.8% (n = 5) were achieved for the determination of 1.8 and 8.8 ng mL{sup −1} AA, respectively. This novel QDs nanosensor based on IFE could provide noticeable advantages of simplicity, convenience, cost-effectiveness, and sensitivity. This method was successfully applied for the detection of ascorbic acid in human real samples serums. - Highlights: • A sensitive and simple method has been developed for detection of ascorbic acid. • Silver nanoparticles as a strong quencher were prepared via the one-step reduction. • Its absorption band covered both emission and excitation bands of CdTe QDs. • So, the fluorescence of CdTe QDs quenching due to Inner filter effect.

  19. Work Function and Conductivity of Inkjet-Printed Silver Layers: Effect of Inks and Post-treatments

    Science.gov (United States)

    Mitra, Dana; Mitra, Kalyan Yoti; Dzhagan, Volodymyr; Pillai, Nikhil; Zahn, Dietrich R. T.; Baumann, Reinhard R.

    2018-03-01

    The electronic properties of a printed layer are influenced by a number of factors, including the nature of the ink (nanoparticle- or solution-based), ink composition (solvents, additives, concentration), and post-treatment technologies, especially sintering. One of the major challenges in the field of printed electronics is achieving the desired performance, for example, in terms of conductivity, resistivity, or work function (WF). This work investigates the dependence of sheet resistance and WF on various sintering methodologies. Four different silver nanoparticle inks were inkjet-printed on a flexible polymeric foil and post-treated by thermal sintering (in an oven) or novel sintering processes using infrared or intense pulsed light. The surfaces of the printed and sintered layers were investigated optically, and various inhomogeneities in the layer surface were observed, varying from a smooth to a highly rough appearance with ring-shaped drying structures. An analysis of the sheet resistance revealed notable variation among the various inks and sintering methodologies used. Here, for the very first time, WF is measured and evaluated as a function of sintering methodology and silver ink, and the respective layer formation characteristics realized with the inkjet printing technology. The WF values obtained by ultraviolet photoemission show a similar spread and allow unambiguous trends to be tracked with respect to the type of ink and sintering method used. The values of the WF obtained range from 3.7 eV to 4.3 eV, approaching the reported bulk values of 4.3-4.7 eV. The various silver inks resulted in different WFs when the same sintering method was used, while the same silver ink resulted in different WFs when various sintering methods were applied. Therefore, it is believed that the WF can be tuned over a broad range in a controlled manner to satisfy electronic device requirements.

  20. A nose-to-nose comparison of the physiological effects of exposure to ionic silver versus silver chloride in the European eel (Anguilla anguilla) and the rainbow trout (Oncorhynchus mykiss)

    DEFF Research Database (Denmark)

    Grosell, M.; Hogstrand, C.; Wood, C.M.

    2000-01-01

    investigated during acute exposure to silver, using concentrations varying from 3 to 22 mu g silver l(-1). Silver was present either predominantly in the form of ionic silver, or in the form of silver chloride complexes (AgClaq). Inhibition of the branchial Na+,K+-ATPase enzyme activity and the active influx...

  1. Study on thermal effects & sulfurized additives, in lubricating greases

    Science.gov (United States)

    Shah, Ami Atul

    Lithium Base grease constitutes about 50% of market. The greases are developed to be able to work in multiple working conditions and have longer working life. Greases with extreme pressure additives and anti-wear additives have been developed as a solution to many of the applications. These developed greases are tested under ASTM D2266 testing conditions to meet the requirements. The actual working conditions, although, differ than the real testing conditions. The loading, speed and temperature conditions can be more harsh, or fluctuating in nature. The cyclic nature of the parameters cannot be directly related to the test performance. For this purpose studies on the performance under spectrum loading, variable speed and fluctuating temperature must be performed. This study includes tests to understand the effect of thermal variation on some of the most commonly used grease additives that perform well under ASTM D2266 testing conditions. The studied additives include most widely used industrial extreme pressure additive MoS2. Performance of ZDDP which is trying to replace MoS2 in its industrial applications has also been studied. The tests cover study of extreme pressure, anti-wear and friction modifier additives to get a general idea on the effects of thermal variation in three areas. Sulphur is the most common extreme pressure additive. Sulphur based MoS 2 is extensively used grease additive. Study to understand the tribological performance of this additive through wear testing and SEM/EDX studies has been done. This performance is also studied for other metallic sulfides like WS2 and sulphur based organic compound. The aim is to study the importance of the type of bond that sulphur shares in its additive's structure on its performance. The MoS2 film formation is found to be on the basis of the FeS formation on the substrate and protection through sacrificial monolayer deposition of the MoS2 sheared structure. The free Mo then tends to oxidise. An attempt to

  2. Effect of polymer additives on transition in pipe flow

    Energy Technology Data Exchange (ETDEWEB)

    Castro, W; Squire, W

    1967-09-01

    Small amounts of long-chain, water-soluble polymers have a marked effect on turbulent flow resulting in appreciable reduction of turbulent friction. The maximum reduction in pipe flow resistance is obtained at such low concentrations that the density and viscosity are not altered appreciably. The minimum friction curve varies as Re-2/3 and appears to be the same for all effective additives tested. The transition process is affected by these additives. Quantitative results are presented showing a reduction in the intensity of the turbulent flashes and the fraction of the time the flow is turbulent at a given Reynolds number. (13 refs.)

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

    Directory of Open Access Journals (Sweden)

    Vasyl Syrvatka

    2014-02-01

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

  4. Evaluation of genotoxic effect of silver nanoparticles (Ag-Nps) in vitro and in vivo

    International Nuclear Information System (INIS)

    Tavares, Priscila; Balbinot, Fernanda; Martins de Oliveira, Hugo; Elibio Fagundes, Gabriela; Venâncio, Mireli; Vieira Ronconi, João Vitor; Merlini, Aline; Streck, Emílio L.; Marques da Silva, Paula; Moraes de Andrade, Vanessa

    2012-01-01

    Silver nanoparticles (Ag-NPs) are the most prominent nanoproducts. Due to their antimicrobial activity, they have been incorporated in different materials, such as catheters, clothes, electric home appliance, and many others. The genotoxicity of Ag-NPs (5–45 nm), in different concentrations and times of exposure, was evaluated by the comet assay in in vitro and in vivo conditions, respectively, using human peripheral blood and Swiss mice. The results showed the genotoxic effect of Ag-NPs in vitro, in all the doses tested in the initial hour of exposure, possibly through the reactive oxygen species generation. Nevertheless, the values for this damage decrease with time, indicating that the DNA may have been restored by the repair system. In the in vivo conditions, we found no genotoxicity of Ag-NPs in any hour of exposure and any dose investigated, which can be attributed to the activation of a cellular antioxidant network and the hydrophobic nature of Ag-NPs. Now, it is absolutely necessary to investigate the role of Ag-NPs in different cell lines in vivo.

  5. The effect of cations on sperm motility performance and fertilizing ability of silver carp Hypophtalmychtis molitrix

    Directory of Open Access Journals (Sweden)

    Khara H.

    2012-01-01

    Full Text Available The objective of the study was to investigate the effect of saline solution containing cations (Na+, K+, Ca+2, Mg+2 on sperm motility performance (duration of sperm motility and percentage of motile spermatozoa and fertilizing capacity of sperm (fertilization rate, hatching rate, larvae length during hatching, larvae length during active feeding and survival rate in silver carp. The results suggested that solutions containing ions did not improve the duration of sperm motility. The same was observed for the percentage of motile spermatozoa. Fertilization rate influenced by solutions containing Ca+2, and other ions could not affect this parameter. The results showed that hatching rate was higher in solutions containing 99 mEq/L NaCl, 2 mEq/L MgCl2 and 2, 4 mEq/L CaCl2 respectively. Also, survival rate was higher in the solution containing 2 mEq/L MgCl2 and 36 mg/dL KCl respectively.With regard to the obtained results, it was concluded that using appropriate activation medium can improve quality of fish sperm and subsequently increases artificial reproduction performance.

  6. Synergistic effects of iodine and silver ions co-implanted in 6H-SiC

    Science.gov (United States)

    Kuhudzai, R. J.; Malherbe, J. B.; Hlatshwayo, T. T.; van der Berg, N. G.; Devaraj, A.; Zhu, Z.; Nandasiri, M.

    2015-12-01

    Motivated by the aim of understanding the release of fission products through the SiC coating of fuel kernels in modern high temperature nuclear reactors, a fundamental investigation is conducted to understand the synergistic effects of implanted silver (Ag) and iodine (I) in 6H-SiC. The implantation of the individual species, as well as the co-implantation of 360 keV ions of I and Ag at room temperature in 6H-SiC and their subsequent annealing behaviour has been investigated by Secondary Ion Mass Spectrometry (SIMS), Atom Probe Tomography (APT) and X-ray Photoelectron Spectroscopy (XPS). SIMS and APT measurements indicated the presence of Ag in the co-implanted samples after annealing at 1500 °C for 30 h in sharp contrast to the samples implanted with Ag only. In samples implanted with Ag only, complete loss of the implanted Ag was observed. However, for I only implanted samples, some iodine was retained. APT of annealed co-implanted 6H-SiC showed clear spatial association of Ag and I clusters in SiC, which can be attributed to the observed I assisted retention of Ag after annealing. Such detailed studies will be necessary to identify the fundamental mechanism of fission products migration through SiC coatings.

  7. Spectroscopic attributes of Sm3+ doped magnesium zinc sulfophosphate glass: Effects of silver nanoparticles inclusion

    Science.gov (United States)

    Ahmadi, F.; Hussin, R.; Ghoshal, S. K.

    2017-11-01

    We report the modified optical properties of Sm3+ doped magnesium zinc sulfophosphate glass system with silver nanoparticles (Ag NPs) inclusion. Three glass samples were prepared using melt quenching method and characterized. TEM images revealed the nucleation of Ag NPs with average diameter ≈12.50 nm. The UV-Vis-NIR spectra showed thirteen absorption bands. The surface plasmon resonance (SPR) band of Ag NPs was manifested at 446 nm. FTIR spectra disclosed the bonding vibrations for P-O bonds, P-O-P linkages, and PO2 units. Ag NPs concentration dependent bonding parameters and Judd-Ofelt (JO) intensity parameters were calculated. The JO parameter Ω2 was reduced with the increase of Ag NPs contents, indicating the ionicity and symmetry enhancement between Sm3+ ions with their surrounding ligands. The emission spectra of all samples under the excitation wavelength of 402 nm exhibited four significant peaks centered at 562, 599, 644 and 702 nm which are allocated to 4G5/2 →6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions, respectively. Inclusion of Ag NPs was discerned to augment the luminescence intensity by a factor of two, which was majorly ascribed to the local field effect of Ag NPs and subsequent energy transfer from the NPs to Sm3+ ions.

  8. Combined effects of silver nanoparticles and mercury on gill histopathology of zebrafish (Danio rerio

    Directory of Open Access Journals (Sweden)

    Borhan Mansouri

    2016-06-01

    Full Text Available Objective: To evaluate the combined effects of silver nanoparticles (Ag NPs and Hg2+ on the gill histopathology of zebrafish (Danio rerio under the controlled conditions. Methods: In this study, one non-lethal concentration of Ag NPs (0.1 mg/L, six concentrations of Hg2+ (0.001, 0.005, 0.01, 0.05, 0.1 and 0.2 mg/L, and six mixture concentrations of Ag NPs and Hg2+ (0.1 plus 0.001, 0.005, 0.01, 0.05, 0.1, and 0.2 mg/L were used as the control group. After 4 days of exposure, samples were prepared for gill histology. Results: The results showed that notable damages were observed in aneurism, such as vacuolation of secondary lamella, fusion, hypertrophy, mucus secretion and necrosis. Moreover, our findings indicated that the Hg2+ and Ag NPs alone led to shorter secondary lamella length and smaller lamellae’s diameter of gills compared to the mixture of Ag NPs and Hg2+. However, the extent of damages in gill tissues after exposure to mixture of Ag NPs and Hg2+ was lower than Hg2+ ions and Ag NPs. Conclusions: It appears that the presence of Ag NPs can potentially reduce the toxicity of Hg2+ ions. However, to assess the toxicity mechanisms of nanoparticles in presence of pollutants, further studies should be encouraged.

  9. Evaluation of genotoxic effect of silver nanoparticles (Ag-Nps) in vitro and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, Priscila; Balbinot, Fernanda; Martins de Oliveira, Hugo; Elibio Fagundes, Gabriela [PPGCS, Universidade do Extremo Sul Catarinense, Laboratorio de Biologia Celular e Molecular (Brazil); Venancio, Mireli; Vieira Ronconi, Joao Vitor; Merlini, Aline [Universidade do Extremo Sul Catarinense, Laboratorio de Sintese de Complexos Multifuncionais (Brazil); Streck, Emilio L. [Programa de Pos-Graduacao em Ciencias da Saude, Unidade Academica de Ciencias da Saude, Universidade do Extremo Sul Catarinense, Laboratorio de Fisiopatologia Experimental (Brazil); Marques da Silva, Paula [Universidade do Extremo Sul Catarinense, Laboratorio de Sintese de Complexos Multifuncionais (Brazil); Moraes de Andrade, Vanessa, E-mail: vmoraesdeandrade@yahoo.com.br [PPGCS, Universidade do Extremo Sul Catarinense, Laboratorio de Biologia Celular e Molecular (Brazil)

    2012-03-15

    Silver nanoparticles (Ag-NPs) are the most prominent nanoproducts. Due to their antimicrobial activity, they have been incorporated in different materials, such as catheters, clothes, electric home appliance, and many others. The genotoxicity of Ag-NPs (5-45 nm), in different concentrations and times of exposure, was evaluated by the comet assay in in vitro and in vivo conditions, respectively, using human peripheral blood and Swiss mice. The results showed the genotoxic effect of Ag-NPs in vitro, in all the doses tested in the initial hour of exposure, possibly through the reactive oxygen species generation. Nevertheless, the values for this damage decrease with time, indicating that the DNA may have been restored by the repair system. In the in vivo conditions, we found no genotoxicity of Ag-NPs in any hour of exposure and any dose investigated, which can be attributed to the activation of a cellular antioxidant network and the hydrophobic nature of Ag-NPs. Now, it is absolutely necessary to investigate the role of Ag-NPs in different cell lines in vivo.

  10. Silver colloidal nanoparticles: effect on matrix composition and structure of Candida albicans and Candida glabrata biofilms.

    Science.gov (United States)

    Monteiro, D R; Silva, S; Negri, M; Gorup, L F; de Camargo, E R; Oliveira, R; Barbosa, D B; Henriques, M

    2013-04-01

    The aim of this study was to assess the effect of different silver nanoparticles (SN) concentrations on the matrix composition and structure of Candida albicans and Candida glabrata biofilms. Candida biofilms were developed in 6-well microtiter plates during 48 h. After, these biofilms were exposed to 13.5 or 54 μg SN ml(-1) for 24 h. Then, extracellular matrices were extracted from biofilms and analysed chemically in terms of proteins, carbohydrates and DNA. To investigate the biofilm structure, scanning electron microscopy (SEM) and epifluorescence microscopy were used. SN interfered with the matrix composition of Candida biofilms tested in terms of protein, carbohydrate and DNA, except for the protein content of C. albicans biofilm. By SEM, Candida biofilms treated with SN revealed structural differences, when compared with the control groups. Further, SN showed a trend of agglomeration within the biofilms. Epifluorescence microscopy images suggest that SN induced damage on cell walls of the Candida isolates tested. In general, irrespective of concentration, SN affected the matrix composition and structure of Candida biofilms and these findings may be related to the mechanisms of biocide action of SN. This study reveals new insights about the behaviour of SN when in contact with Candida biofilms. SN may contribute to the development of therapies to prevent or control Candida infections. © 2012 The Society for Applied Microbiology.

  11. Dimensional scale effects on surface enhanced Raman scattering efficiency of self-assembled silver nanoparticle clusters

    International Nuclear Information System (INIS)

    Fasolato, C.; Domenici, F.; De Angelis, L.; Luongo, F.; Postorino, P.; Sennato, S.; Mura, F.; Costantini, F.; Bordi, F.

    2014-01-01

    A study of the Surface Enhanced Raman Scattering (SERS) from micrometric metallic nanoparticle aggregates is presented. The sample is obtained from the self-assembly on glass slides of micro-clusters of silver nanoparticles (60 and 100 nm diameter), functionalized with the organic molecule 4-aminothiophenol in water solution. For nanoparticle clusters at the micron scale, a maximum enhancement factor of 10 9 is estimated from the SERS over the Raman intensity ratio normalized to the single molecule contribution. Atomic force microscopy, correlated to spatially resolved Raman measurements, allows highlighting the connection between morphology and efficiency of the plasmonic system. The correlation between geometric features and SERS response of the metallic structures reveals a linear trend of the cluster maximum scattered intensity as a function of the surface area of the aggregate. On given clusters, the intensity turns out to be also influenced by the number of stacking planes of the aggregate, thus suggesting a plasmonic waveguide effect. The linear dependence results weakened for the largest area clusters, suggesting 30 μm 2 as the upper limit for exploiting the coherence over large scale of the plasmonic response.

  12. The effect of soil properties on the toxicity of silver to the soil nitrification process.

    Science.gov (United States)

    Langdon, Kate A; McLaughlin, Mike J; Kirby, Jason K; Merrington, Graham

    2014-05-01

    Silver (Ag) is being increasingly used in a range of consumer products, predominantly as an antimicrobial agent, leading to a higher likelihood of its release into the environment. The present study investigated the toxicity of Ag to the nitrification process in European and Australian soils in both leached and unleached conditions. Overall, leaching of soils was found to have a minimal effect on the final toxicity data, with an average leaching factor of approximately 1. Across the soils, the toxicity was found to vary by several orders of magnitude, with concentrations of Ag causing a 50% reduction in nitrification relative to the controls (EC50) ranging from 0.43 mg Ag/kg to >640 mg Ag/kg. Interestingly, the dose-response relationships in most of the soils showed significant stimulation in nitrification at low Ag concentrations (i.e., hormesis), which in some cases produced responses up to double that observed in the controls. Soil pH and organic carbon were the properties found to have the greatest influence on the variations in toxicity thresholds across the soils, and significant relationships were developed that accounted for approximately 90% of the variability in the data. The toxicity relationships developed from the present study will assist in future assessment of potential Ag risks and enable the site-specific prediction of Ag toxicity. © 2014 SETAC.

  13. Effects of additives on solidification of API separator sludge.

    Science.gov (United States)

    Faschan, A; Tittlebaum, M; Cartledge, F; Eaton, H

    1991-08-01

    API separator sludge was solidified with various combinations of binders and absorbent soil additives. The binders utilized were Type I Portland Cement, Type C Flyash, and a 1:1 combination of the two. The soil additives used were bentonite, diatomite, Fuller's earth, and two brands of chemically altered bentonites, or organoclays. The effectiveness of the solidification materials was based on their effect on the physical and leaching characteristics of the sludge.It was determined the Portland cement and combination binders provided the sludge with adequate physical and strength characteristics. It was also determined the affinity of each additive for water had an important influence on the physical characteristics of the solidified sludge. The results of the leaching procedure indicated the binders alone reduced the leachability of organic constituents from the sludge by 1/5 to 1/10. It appeared the use of the additives with the binders may have further reduced the leachability of constituents from sludge, with the incorporation of the organoclay additives further reducing leachability by up to 1/2. Also, it appeared the absorbing capacity of the additives was directly related to their ability to reduce the leachability of organic constituents from the sludge.

  14. Effects of Short-Term Exposure to Sublethal Concentrations of Silver Nanoparticles on Histopathology and Electron Microscope Ultrastructure of Zebrafish (Danio Rerio Gills

    Directory of Open Access Journals (Sweden)

    Borhan Mansouri

    2015-11-01

    Full Text Available Background: The increasing use of nanomaterials and nanoproducts has increased the possibility of contamination of the environment, which may have adverse effects on different organisms. The aim of this study was to evaluate the effects of silver nanoparticles on histopathology and gill ultrastructure of zebrafish (Danio rerio under laboratory conditions. Methods: Zebrafish were exposed to four concentrations of silver nanoparticles (0.0015, 0.00375, 0.0075, and 0.015 mg/l for a period of 4 days. Gill ultrastructure and histopathological changes were studied using scanning electron microscope and haematoxylin - eosin staining. Results: Exposure to silver nanoparticles significantly (P < 0.001 increased the diameter of gill filaments and secondary lamellae, while silver nanoparticles significantly reduced the length of the secondary gills in zebrafish. Moreover, other changes such as vacuolization, dilated and clubbed tips, hyperplasia, edema, fusion, swelling of mucocytes, hypertrophy, and necrosis were observed. The effects of silver nanoparticles in zebrafish gills were dose dependent. Conclusion: Based on the adverse effects of AgNPs on zebrafish gills, silver nanoparticle solutions can be hazardous pollutants for the environment.

  15. Effects of additives on glyphosate activity in purple nutsedge

    International Nuclear Information System (INIS)

    Rungsit Suwanketnikom

    1998-01-01

    Effects of additives on 14 C-glyphosate penetration into purple nutsedge leaves were examined in the laboratory and efficacy of glyphosate for purple nutsedge control was studied in the greenhouse and field. The addition of (NH 4 ) 2 SO 4 at 1.0% (v/v) + diesel oil at 1,0% (v/v) + Tendal at 1.0% (v/v) increased 14 C-glyphosate penetration into nutsedge leaves more than the addition of either one alone. (NH 4 ) 2 SO 4 at 1.0% + diesel oil at 1.0% + Tendal at 0.12 or 0.25% increased the phytotoxicity of glyphosate at 0.5 and 0.75 kg, a.e./ha on nutsedge plants in the greenhouse but not in the field. Additives did not enhance glyphosate activity by reducing the number of nutsedae tubers. (author)

  16. Spectroscopic Studies on the Effect of Some Ferrocene Derivatives in the Formation of Silver Nanoparticles.

    Science.gov (United States)

    Sanyal, Manik Kumar; Biswas, Bipul; Chowdhury, Avijit; Mallik, Biswanath

    2016-06-01

    Silver nanoparticles were prepared by microwave assisted method using silver nitrate as precursor in the presence of some ferrocene derivatives. The formation of the silver nanoparticles was monitored using UV-Vis spectroscopy. The UV-Vis spectroscopy revealed the formation of silver nanoparticles by exhibiting typical surface plasmon absorption band. The position of plasmon band (406-429 nm) was observed to depend on the nature of a particular ferrocene derivative used. TEM images indicated that the nanoparticles were spherical in shape and well-dispersed. Quantum dots (3.2 nm) were prepared by using ferrocenecarboxylic acid. The surface plasmon absorption band has shown red shift with increasing concentration of ferrocene derivative. For different duration of microwave heating time, intensity of absorption spectra in general was found to increase except in presence of ferrocene carbaldehyde where it decreased. Time-dependent spectra have indicated almost stable position of the surface plasmon band with increasing time of observation confirming that the as prepared silver nanoparticles did not aggregate with lapse of time.

  17. Statistical study of chemical additives effects in the waste cementation

    International Nuclear Information System (INIS)

    Tello, Cledola C.O. de; Diniz, Paula S.; Haucz, Maria J.A.

    1997-01-01

    This paper presents the statistical study, that was carried out to analyse the chemical additives effect in the waste cementation process. Three different additives from two industries were tested: set accelerator, set retarder and super plasticizers, in cemented pates with and without bentonite. The experiments were planned in accordance with the 2 3 factorial design, so that the effect of each type of additive, its quantity and manufacturer in cemented paste and specimens could be evaluated. The results showed that the use of these can improve the cementation process and the product. The admixture quantity and the association with bentonite were the most important factors affecting the process and product characteristics. (author). 4 refs., 9 figs., 4 tabs

  18. Effect of increased manganese addition and mould type on the ...

    Indian Academy of Sciences (India)

    Administrator

    Effect of increased manganese addition and mould type on the slurry erosion characteristics of .... slurry erosion data in the form of bar diagrams for 5M24 and 10M24 ... being bigger in size with higher austenite retention and the attendant ...

  19. Effect Of Formulating Additives On The Properties Of Ibuprofen Tablets

    African Journals Online (AJOL)

    A study of the comparative effects of different formulating additives and film coating on the properties of ibuprofen tablets was made. The tested properties were hardeness (H), friability (F), the disintegration time (D) and dissolution characteristics of ibuprofen tablets. The hardeness, friability, the hardeness friability ratio ...

  20. Effect of borax additive on the dielectric response of polypyrrole

    Indian Academy of Sciences (India)

    2018-03-29

    Mar 29, 2018 ... fore, borax additive is effective on the properties of composite material. 2.5 Particle size of .... of a very mobile group of electric dipoles in PPy–50 wt% ..... [9] Cavdar A D, Mengelo˘glu F and Karakus K 2015 Measurement. 60 6.

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

    Science.gov (United States)

    Naik, K; Kowshik, M

    2017-11-01

    Silver has attracted a lot of attention as a powerful, broad spectrum and natural antimicrobial agent since the ancient times because of its nontoxic nature to the human body at low concentrations. It has been used in treatment of various infections and ulcers, storage of water and prevention of bacterial growth on the surfaces and within materials. However, there are numerous medical and health benefits of colloidal or nanosilver apart from its microbicidal ability which as yet has not been fully embraced by the medical community. These include antiplatelet activity, antioxidant effect, anticancer activity, wound healing and bone regeneration, enhancement of immunity, and increase in antibiotic efficiency. Additionally silver also provides protection against alcohol toxicity, upper respiratory tract infections and stomach ailments. Although nanosilver has been proposed for various topical applications, its usage by ingestion and inhalation remains controversial due to the lack of detailed and precise toxicity information. These beneficial properties of silver can be utilized by using silver at very low concentrations which are not harmful to the human body and environment. The following review discusses the diverse medical applications of silver and further recommends human clinical studies for its in vivo usage. #x00A9; 2017 The Society for Applied Microbiology.

  2. EFFECT OF NICKEL AND COBALT ADDITIONS ON INFILTRATION BEHAVIOR, MICROSTRUCTURE AND HARDNESS OF W-AG COMPOSITES

    Directory of Open Access Journals (Sweden)

    N Parvin

    2014-12-01

    Full Text Available In this research, infiltration behavior of W-Ag composite compacts with Nickel and Cobalt as additives has been investigated. Nickel and Cobalt were added to Tungsten powder by two distinct methods: mixing elementally and reduction of salt solution. The coated Tungsten powders were compacted under controlled pressures to make porous skeleton with 32-37 vol. % porosity. Infiltration process was carried out at 1100 ̊C under a reducing atmosphere for 1h. The effect of additives on infiltration of Ag and density were evaluated by SEM and Archimedes methods. Properties of the specimens were compared following two distinct processes namely: I sintering simultaneously with infiltration process and II sintering prior to infiltration (pre-sintering process. It was found that specimens which were pre-sintered and then infiltrated with molten silver represent higher hardness and finer microstructure than the specimens infiltrated simultaneously with sintering.

  3. Antifungal Effects of Silver Nanoparticles (AgNPs) against Various Plant Pathogenic Fungi.

    Science.gov (United States)

    Kim, Sang Woo; Jung, Jin Hee; Lamsal, Kabir; Kim, Yun Seok; Min, Ji Seon; Lee, Youn Su

    2012-03-01

    This research is concerned with the fungicidal properties of nano-size silver colloidal solution used as an agent for antifungal treatment of various plant pathogens. We used WA-CV-WA13B, WA-AT-WB13R, and WA-PR-WB13R silver nanoparticles (AgNPs) at concentrations of 10, 25, 50, and 100 ppm. Eighteen different plant pathogenic fungi were treated with these AgNPs on potato dextrose agar (PDA), malt extract agar, and corn meal agar plates. We calculated fungal inhibition in order to evaluate the antifungal efficacy of silver nanoparticles against pathogens. The results indicated that AgNPs possess antifungal properties against these plant pathogens at various levels. Treatment with WA-CV-WB13R AgNPs resulted in maximum inhibition of most fungi. Results also showed that the most significant inhibition of plant pathogenic fungi was observed on PDA and 100 ppm of AgNPs.

  4. Effect of composition and temperature on the second harmonic generation in silver phosphate glasses

    Science.gov (United States)

    Konidakis, I.; Psilodimitrakopoulos, S.; Kosma, K.; Lemonis, A.; Stratakis, E.

    2018-01-01

    We herein employ nonlinear laser imaging microscopy to explicitly study the dynamics of second harmonic generation (SHG) in silver iodide phosphate glasses. While glasses of this family have gained extensive scientific attention over the years due to their superior conducting properties, considerably less attention has been paid to their unique nonlinear optical characteristics. In the present study, firstly, it is demonstrated that SHG signal intensity is enhanced upon increasing silver content due to the random formation of silver microstructures within the glass network. Secondly, the SHG temperature dynamics were explored near the glass transition temperature (Tg) regime, where significant glass relaxation phenomena occur. It is found that heating towards the Tg improves the SHG efficiency, whereas above Tg, the capacity of glasses to generate second harmonic radiation is drastically suppressed. The novel findings of this work are considered important in terms of the potential employment of these glasses for the realization of advanced photonic applications like optical-switches and wavelength conversion devices.

  5. Morphology Effect of Silver Nanostructures on the Performance of a P3HT:Graphene:AgNs-Based Active Layer Obtained via Dip Coating

    Directory of Open Access Journals (Sweden)

    Alí Gómez-Acosta

    2016-01-01

    Full Text Available We report the effect of the use of different silver nanostructures (AgNs layers deposited via dip coating onto a poly(3-hexylthiophene (P3HT and solution processable functionalized graphene (SPFGraphene composite film intended to be used as active layer in BHJ devices. SPFGraphene was added to P3HT in a ratio of 1.5 wt%. The best results were achieved when a layer of silver nano-pseudospheres (AgNPSs obtained after 10 immersion cycles was used as coating; in this case the highest light trapping and efficiency percent (η=0.23% were achieved. This means an increase of ~11.3% in comparison with the efficiency of the noncoated P3HT:SPFGraphene composite. Results also indicate that graphene was successfully functionalized in order to obtain appropriate dispersion in P3HT and that such conjugated polymer remained unaltered after the addition of SPFGraphene. Finally, it can be concluded that the electrical properties of the as-synthesized films are dependent on the shape and concentration of the AgNs deposited via dip coating.

  6. Characterization of silver nanoparticles synthesized using Urtica dioica Linn. leaves and their synergistic effects with antibiotics

    Directory of Open Access Journals (Sweden)

    Kumari Jyoti

    2016-07-01

    Full Text Available In continuation of the efforts for synthesizing silver nanoparticles (AgNPs by green chemistry route, here we report a facile bottom-up ‘green’ route for the synthesis of AgNPs using aqueous leaves extract of Urtica dioica (Linn.. The synthesized AgNPs were characterized by UV-vis spectroscopy, X-ray diffraction (XRD, Fourier transform-infrared spectroscopy (FTIR, Zeta-sizer and Zeta-potential, Scanning electron microscopy (SEM, Energy dispersive X-ray (EDX spectroscopy, Transmission electron microscopy (TEM and Selected area electron diffraction (SAED. The results obtained from various characterizations revealed that AgNPs were in the size range of 20–30 nm and crystallized in face-centered-cubic structure. The antibacterial activity against Gram-positive (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Salmonella typhimurium bacterial pathogens was demonstrated by synthesized nanoparticles. Further, synergistic effects of AgNPs with various antibiotics were evaluated against above mentioned bacterial pathogens. The results showed that AgNPs in combination with antibiotics have better antibacterial effect as compared with AgNPs alone and hence can be used in the treatment of infectious diseases caused by bacteria. The maximum effect, with a 17.8 fold increase in inhibition zone, was observed for amoxicillin with AgNPs against S. marcescens proving the synergistic role of AgNPs. Therefore, it may be used to augment the activities of antibiotics.

  7. Silver Sulfidation in Thermophilic Anaerobic Digesters and Effects on Antibiotic Resistance Genes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bojeong; Miller, Jennifer H.; Monsegue, Niven; Levard, Clément; Hong, Yanjuan; Hull, Matthew S.; Murayama, Mitsuhiro; Brown, Gordon E.; Vikesland, Peter J.; Knocke, William R.; Pruden, Amy; Hochella, Michael F.

    2015-12-15

    Physical and chemical transformations and biological responses of silver nanoparticles (AgNPs) in wastewater treatment systems are of particular interest because of the extensive existing and continually growing uses of AgNPs in consumer products. In this study, we investigated the transformation of AgNPs and AgNO3 during thermophilic anaerobic digestion and effects on selection or transfer of antibiotic resistance genes (ARGs). Ag2S-NPs, sulfidation products of both AgNPs and AgNO3, were recovered from raw and digested sludges and were analyzed by analytical transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS). TEM and XAS revealed rapid (≤20 min) Ag sulfidation for both Ag treatments. Once transformed, Ag2S-NPs (as individual NPs or an NP aggregate) persisted for the duration of the batch digestion. The digestion process produced Ag2S-NPs that were strongly associated with sludge organics and/or other inorganic precipitates. Ag treatments (up to 1,000 mg Ag/kg) did not have an impact on the performance of thermophilic anaerobic digesters or ARG response, as indicated by quantitative polymerase chain reaction measurements of sul1, tet(W), and tet(O) and also intI1, an indicator of horizontal gene transfer of ARGs. Thus, rapid Ag sulfidation and stabilization with organics effectively sequester Ag and prevent biological interactions with the digester microbial community that could induce horizontal gene transfer or adversely impact digester performance through antimicrobial activity. This finding suggests that sulfide-rich anaerobic environments, such as digesters, likely have a high buffer capacity to mitigate the biological effects of AgNPs.

  8. Antimicrobial and cytotoxicity effect of silver nanoparticle synthesized by Croton bonplandianum Baill. leaves

    Directory of Open Access Journals (Sweden)

    K. Khanra

    2016-01-01

    Full Text Available Objective(s: For the development of reliable, ecofriendly, less expensive process for the synthesis of silver nanoparticles and to evaluate the bactericidal, and cytotoxicity properties of silver nanoparticles synthesized from root extract of Croton bonplandianum, Baill. Materials and Methods: The synthesis of silver nanoparticles by plant part of Croton bonplandianum was carried out.  The formation of nanoparticles was confirmed by Transmission Electron Microscopy (TEM, Scanning Electron Microscopy (SEM, XRD and UV-Vis spectrophotometric analysis.  The biochemical properties were assayed by antibacterial study, cytotoxicity assay using cancer cell line.  Results: The formation of silver nanoparticles was confirmed by UV-VIS spectroscopic analysis which showed absorbance peak at 425 nm.  X-ray diffraction photograph indicated the face centered cubic structure of the synthesized AgNPs.  TEM has displayed the different dimensional images of biogenic silver nanoparticles with particle size distribution ranging from 15-40 nm with an average size of 32 nm. Silver particles are spherical in shape, clustered.  The EDX analysis was used to identify the elemental composition of synthesized AgNPs. Antibacterial activity of the synthesized AgNPs against three Gram positive and Gram negative bacteria strains like Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa carried out showed significant zones of inhibition. The cytotoxicity study by AgNPS also showed cytotoxicity on ovarian cancer cell line PA-1 and lung epithelial cancer cell line A549.  Conclusion: The present study confirms that the AgNPs have great promise as antibacterial, and anticancer agent.

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

    Science.gov (United States)

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

  10. Green biosynthesis of silver nanoparticles using pomegranate peel and inhibitory effects of the nanoparticles on aflatoxin production

    International Nuclear Information System (INIS)

    Monira, A.O.; Mohammad, M.A.; Ashraf, H.A.

    2017-01-01

    In this work, pomegranate peel has been used as a natural and safe method for biosynthesis of silver nanoparticles. The synthesis of silver nanoparticles was confirmed using UV spectroscopy, which showed a peak around a wavelength of 437 nm. The morphology showed spherical and monodispersed nanoparticles with a size range between 5-50 nm. Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD) experiments revealed their crystalline nature. Active functional groups in the synthesized silver nanoparticles were determined using Fourier transform infrared (FTIR) spectrometers contained four bands at 3281.21 cm/sup -1/, possibly indicating the participationof O-H functional group. The peak take place at 1,636.22 cm/sup -1/ may be pointed to C = N bending in the amide group or C = O stretching in carboxyl. Transfer in this peak (from 1,641 to 1,643 cm/sup -1/) shown the possible role of amino groups or carboxyl in nanoparticle synthesis. The peaks at 431.95 and 421.28 cm/sup -1/ be related to AgNPs bonding with oxygen from hydroxyl groups which confirm the role of pomegranate peel as a reducing agent. Furthermore, we investigated effects of these nanoparticles on aflatoxin B1 production by the fungus Aspergillus flavus, isolated from hazelnut. The results found that aflatoxin production in all A. flavus isolates decreased with an increase in the concentration of silver nanoparticles. Maximum suppression of aflatoxin production was recorded at a nanoparticle concentration of 150 ppm. (author)

  11. Effect of magnetic field and silver nanoparticles on yield and water use efficiency of Carum copticum under water stress conditions

    Directory of Open Access Journals (Sweden)

    Seghatoleslami Mohammadjavad

    2015-03-01

    Full Text Available Normally the productivity of cropping systems in arid and semi- arid regions is very low. The sustainable agricultural systems try to find out environmental friendly technologies based on physical and biological treatments to increase crop production. In this study two irrigation treatments (control and water stress and six methods of fertilizer treatment (control, NPK-F, using magnetic band- M, using silver nano particles- N, M+N and M+N+50% F on performance of ajowan were compared. Results showed that treatments with magnetic field or base fertilizer had more yield compared to the control and silver nanoparticles (N treatments. Application of silver nanoparticles had no positive effect on yield. The highest seed and biomass WUE achieved in base fertilizer or magnetic field treatments. Under water stress treatment, seed WUE significantly increased. In conclusion magnetic field exposure, probably by encourage nutrient uptake efficiency could be applied to reduce fertilizer requirement. On the other hand the cultivation of plants under low MF could be an alternative way of WUE improving.

  12. The effects of honey compared to silver sulfadiazine for the treatment of burns: A systematic review of randomized controlled trials.

    Science.gov (United States)

    Aziz, Zoriah; Abdul Rasool Hassan, Bassam

    2017-02-01

    Evidence from animal studies and trials suggests that honey may accelerate wound healing. The objective of this review was to assess the effects of honey compared with silver dressings on the healing of burn wounds. Relevant databases for randomized controlled trials (RCTs) of honey compared with silver sulfadiazine (SSD) were searched. The quality of the selected trials was assessed using the Cochrane Risk of Bias Assessment Tool. The primary endpoints considered were wound healing time and the number of infected wounds rendered sterile. Nine RCTs met the inclusion criteria. Based on moderate quality evidence there was a statistically significant difference between the two groups, favoring honey in healing time (MD -5.76days, 95% CI -8.14 to -3.39) and the proportions of infected wounds rendered sterile (RR 2.59; 95% CI 1.58-2.88). The available evidence suggests that honey dressings promote better wound healing than silver sulfadiazine for burns. Copyright © 2016 Elsevier Ltd and ISBI. All rights reserved.

  13. Effects of ionic surfactants on the morphology of silver nanoparticles using Paan (Piper betel) leaf petiole extract.

    Science.gov (United States)

    Khan, Zaheer; Bashir, Ommer; Hussain, Javed Ijaz; Kumar, Sunil; Ahmad, Rabia

    2012-10-01

    Stable silver nanoparticles were synthesized by the reduction of silver ions with a Paan (Piper betel) leaf petiole extract in absence and presence of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate (SDS). The reaction process was simple and convenient to handle, and was monitored using ultraviolet-visible spectroscopy. Absorbance of Ag-nanoparticles increases with the concentrations of Paan leaf extract, acts as reducing, stabilizing and capping agents. The polyphenolic groups of petiole extract are responsible to the rapid reduction of Ag(+) ions into metallic Ag(0). The results indicated that the shape of the spectra, number of peaks and its position strongly depend on the concentration of CTAB, which played a shape-controlling role during the formation of silver nanoparticles in the solutions, whereas SDS has no significant effect. The morphology (spherical, truncated triangular polyhedral plate and some irregular nanoparticles) and crystalline phase of the particles were determined from transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Effect of embedded silver nanoparticles on refractive index of soda lime glass

    Science.gov (United States)

    Sonal, Sharma, Annu; Aggarwal, Sanjeev

    2018-05-01

    Silver glass nanocomposites were prepared by exposing silver doped soda lime glass slides obtained via ion-exchange reaction to a beam of 200 keV Argon ions (Ar+) at an off normal angle of 400 with doses of 5x1015 ions cm-2 and 1x1016 ions cm-2. These nanocomposites were further characterized using UV-visible spectrophotometer so as to study their transmission and reflection behavior and compute their refractive index and real and imaginary parts of dielectric function.

  15. Disinfection of Spacecraft Potable Water Systems by Passivation with Ionic Silver

    Science.gov (United States)

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

    2011-01-01

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

  16. Silver nanoparticles enhanced luminescence properties of Er³⁺ doped tellurite glasses: Effect of heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Fares, Hssen; Férid, Mokhtar [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Elhouichet, Habib, E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Department of Physics, Sciences Faculty of Tunis, University Tunis ElManar 2092 (Tunisia); Gelloz, Bernard [Graduate School of Engineering, Nagoya University, 2-24-16 Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan)

    2014-09-28

    Tellurite glasses doped Er³⁺ ions and containing Silver nanoparticles (Ag NPs) are prepared using melt quenching technique. The nucleation and growth of Ag NPs were controlled by a thermal annealing process. The X-ray diffraction pattern shows no sharp peak indicating an amorphous nature of the glasses. The presence of Ag NPs is confirmed from transmission electron microscopy micrograph. Absorption spectra show typical surface plasmon resonance (SPR) band of Ag NPs within the 510–550 nm range in addition to the distinctive absorption peaks of Er³⁺ ions. The Judd-Ofelt (J-O) intensity parameters, oscillator strengths, spontaneous transition probabilities, branching ratios, and radiative lifetimes were successfully calculated based on the experimental absorption spectrum and the J-O theory. It was found that the presence of silver NPs nucleated and grown during the heat annealing process improves both of the photoluminescence (PL) intensity and the PL lifetime relative to the ⁴I13/2 → ⁴I15/2 transition. Optimum PL enhancement was obtained after 10 h of heat-treatment. Such enhancements are mainly attributed to the strong local electric field induced by SPR of silver NPs and also to energy transfer from the surface of silver NPs to Er³⁺ ions, whereas the quenching is ascribed to the energy transfer from Er³⁺ ions to silver NPs. Using the Mc Cumber method, absorption cross-section, calculated emission cross-section, and gain cross-section for the ⁴I13/2 → ⁴I15/2 transition were determined and compared for the doped and co-doped glasses. The present results indicate that the glass heat-treated for 10 h has good prospect as a gain medium applied for 1.53 μm band broad and high-gain erbium-doped fiber amplifiers.

  17. The effectiveness of topical colloidal silver in recalcitrant chronic rhinosinusitis: a randomized crossover control trial.

    Science.gov (United States)

    Scott, John R; Krishnan, Rohin; Rotenberg, Brian W; Sowerby, Leigh J

    2017-11-25

    Recalcitrant chronic rhinosinusitis without polyposis (CRSsP) is a challenging condition to manage as traditional medical therapies and surgery fail to provide satisfactory clinical improvements. Colloidal silver (CS), a widely used naturopathic agent, has recently shown anti-biofilm properties both in vitro and within a rhinosinusitis animal model. To date, no trials involving humans have been published in world literature. The purpose of this study was to assess the efficacy of CS as a topical nasal spray in patients with refractory CRSsP. A prospective cohort study was conducted using a convenience sample of 20 randomized patients with crossover methodology, comparing nasal sprays with CS versus saline. Patients sprayed twice daily for six weeks with the first intervention and then switched to the second for the next six weeks, with measurements made at baseline and each time point. Primary outcomes were changes in SNOT-22 and Lund-Kennedy (LK) endoscopic scores. All analysis was non-parametric and was conducted using STATA 14. Twenty-two patients were enrolled in the study with 20 completing the entire protocol. Mean 6-week change in SNOT-22 scores were -2.8 and 1.0 for saline and CS, respectively (p = 0.373). Similarly, mean 6-week change in LK scores were -1.4 and -1.1 for saline and CS, respectively (p = 0.794). Significant period effects were observed with the SNOT-22 score between the randomized groups. No participants experienced negative health effects directly attributable to the administration of intranasal CS. Commercially available CS nasal spray did not demonstrate any meaningful subjective or objective improvements in patients with recalcitrant CRSsP. NCT02403479 . Registered on March 1, 2015.

  18. 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...

  19. Effect of trehalose addition on volatiles responsible for strawberry aroma.

    Science.gov (United States)

    Kopjar, Mirela; Hribar, Janez; Simcic, Marjan; Zlatić, Emil; Pozrl, Tomaz; Pilizota, Vlasta

    2013-12-01

    Aroma is one of the most important quality properties of food products and has a great influence on quality and acceptability of foods. Since it is very difficult to control, in this study the effect of addition of trehalose (3, 5 and 10%) to freeze-dried strawberry cream fillings was investigated as a possible means for retention of some of the aroma compounds responsible for the strawberry aroma. In samples with added trehalose, higher amounts of fruity esters were determined. Increase of trehalose content did not cause a proportional increase in the amount of fruity esters. However, results of our research showed that trehalose addition did not have the same effect on both gamma-decalactone and furaneol.

  20. Effects of additional inertia force on bubble breakup

    International Nuclear Information System (INIS)

    Pan Liangming; Zhang Wenzhi; Chen Deqi; Xu Jianhui; Xu Jianjun; Huang Yanping

    2011-01-01

    Through VOF two-phase flow model, the single bubble deformation and breakup in a vertical narrow channel is numerically investigated in the study based on the force balance at the process of bubble breakup. The effect of surface tension force, the additional inertia force and bubble initial shape on bubble breakup are analyzed according to the velocity variation at the break-up point and the minimum necking size when the bubble is breaking up. It is found that the surface tension force, the additional inertia force and the bubble initial shape have significant effects on the bubble breakup through the fluid injection toward to the bubble, which finally induces the onset of bubble breakup. (authors)

  1. Additional potential effects of nuclear war on ecological systems

    International Nuclear Information System (INIS)

    Hutchinson, T.C.; Harwell, M.A.; Cropper, W.P. Jr.; Grover, H.D.

    1985-01-01

    The authors summarize biological and ecosystem responses to enhanced UV-B, air pollutants, radiation, and fire. The concentrations and biological responses associated with these perturbations are based on current experience and experimentation. Additional research is needed to quantify probable post-nuclear war exposures and potential responses. A summary is provided of all the potential effects of nuclear war on the variety of the Earth's ecosystems, including perturbations from climatic alterations, radiation, pollutants, and UV-B

  2. In vitro studies of the toxic effects of silver nanoparticles on HeLa and U937 cells

    Directory of Open Access Journals (Sweden)

    Kaba SI

    2015-03-01

    Full Text Available Said I Kaba, Elena M Egorova Institute of General Pathology and Pathophysiology, Moscow, Russia Abstract: In the last decade, much attention has been paid to studies of the effect of silver nanoparticles (Ag NPs on tumor cells. Apart from elucidation of the mechanism of NPs’ interaction with mammalian cells, these studies are aimed at discovering new effective antitumor drugs. In this work, we report about the toxic effects of Ag NPs observed on two types of tumor cells: HeLa (adhesive cells and U937 (suspension cells. The Ag NPs were obtained by an original method of biochemical synthesis. Particle size was 13.2±4.72 nm, and zeta potential was -61.9±3.2 mV. The toxicity of Ag NPs in the concentration range 0.5–8.0 µg Ag/mL was determined by means of 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay and cytofluorometry after 4 and 24 hours' incubation. It was found that Ag NPs had high toxicity toward both cell types. The minimal concentrations where a toxicity effect was registered (toxicity thresholds lied in the range 0.5–2.0 µg Ag/mL. In parallel with the Ag NP solution, cells were incubated with water solutions of the NP stabilizer (aerosol-OT and Ag+ ions (as silver nitrate. It was shown that aerosol-OT had no effect on the viability on HeLa cells, but was moderately toxic toward U937, though less dangerous for these cells than Ag NPs. With Ag+ ions, for HeLa no toxic effect was observed, while for U937 they were as toxic as the Ag NPs. The data obtained indicate that Ag NPs as used in this study may prove to be useful for the creation of medicines for cancer therapy. Keywords: silver nanoparticles, cell viability, apoptosis, tumor cells

  3. 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.

  4. Effect of Urea Addition on Soda Pulping of Oak Wood

    OpenAIRE

    Cho, Nam-Seok; Matsumoto, Yuji; Cho, Hee-Yeon; Shin, Soo-Jeong; Oga, Shoji

    2008-01-01

    Many studies have been conducted to find a sulfur-free additive for alkaline pulping liquors that would have an effect similar to that of sulfide in kraft pulping. Some reagents that partially fulfill this role have been found, but they are too expensive to be used in the quantities required to make them effective. As an alternative method to solve air pollution problem and difficulty of pulp bleaching of kraft pulping process, NaOH-Urea pulping was applied. The properties of NaOH-Urea pul...

  5. Effects of Deposited Metallic Silver on Nano-ZnO for the ...

    African Journals Online (AJOL)

    Silver-deposited nano-ZnO samples with different Ag loadings were prepared by a one-pot solvothermal method. The structure, physico-chemical and optical properties of the products were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), diffuse ...

  6. Effects of silver nanoparticles and ions and interactions with first line of defense

    NARCIS (Netherlands)

    Georgantzopoulou, A.

    2015-01-01

    Summary

    Silver nanoparticles (Ag NPs) are among the most promising groups of NPs (particles with all dimensions below 100 nm) for application in numerous consumer products due to their broad spectrum antimicrobial activities. Examples are incorporation in textiles and

  7. Effects of ethylene inhibitors, silver nitrate (AgNO3), cobalt chloride ...

    African Journals Online (AJOL)

    Significant increase in shoot regeneration, leaf chlorophyll content and rooting occurred when silver nitrate (AgNO3), cobalt chloride (CoCl2) or aminooxyacetic acid (AOA) were added to banana culture medium. The highest numbers of shoots per explants shoot length and leaf surface area was obtained when media were ...

  8. Effects of biochar addition on toxic element concentrations in plants

    DEFF Research Database (Denmark)

    Peng, Xin; Deng, Yinger; Peng, Yan

    2018-01-01

    Consuming food contaminated by toxic elements (TEs) could pose a substantial risk to human health. Recently, biochar has been extensively studied as an effective soil ameliorant in situ because of its ability to suppress the phytoavailability of TEs. However, despite the research interest......, the effects of biochar applications to soil on different TE concentrations in different plant parts remain unclear. Here, we synthesize 1813 individual observations data collected from 97 articles to evaluate the effects of biochar addition on TE concentrations in plant parts. We found that (1) the experiment...... type, biochar feedstock and pyrolysis temperature all significantly decreased the TE concentration in plant parts; (2) the responses of Cd and Pb concentrations in edible and indirectly edible plant parts were significantly more sensitive to the effect of biochar than the Zn, Ni, Mn, Cr, Co and Cu...

  9. Green synthesis and antibacterial effect of silver nanoparticles using Eucalyptus camaldulensis

    Directory of Open Access Journals (Sweden)

    Samaneh Dolatabadi

    2017-11-01

    Full Text Available Introduction and Aims: Due to the developing bacterial drug resistance to classical antimicrobial agents, it seems necessary to produce an innovative therapeutic approach to eliminate resistant pathogens. This study aimed to biosynthesis of silver nanoparticles (AgNPs using flowers extract of Eucalyptus camaldulensis and determined of antibacterial activity of produced AgNPs.  Materials and Methods: We used an environmentally friendly extracellular biosynthetic technique for the production of the AgNPs. The reducing agents used to produce the nanoparticles were from the aqueous flowers extract of Eucalyptus camaldulensis. The AgNPs were characterized by color changes, the UV-visible spectroscopy, FTIR analysis, XRD patterns and Scanning Electron Microscopy (SEM technique. The antibacterial activity of AgNPs was investigated against Gram-positive and Gram-negative bacteria ,through broth micro dilution (MIC values and MBC (Minimum bactericidal concentration assays. Results: An absorption peak at 413 nm and the color change to dark brown were corresponding to the plasmon absorbance of AgNPs and then were performed by FTIR and XRD methods. The average size of nanoparticles was observed between 67 and 80 nm. Furthermore, the MIC value of extract against Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa were 3.12, 6.25, and 50 mg/mL, respectively. The corresponding MBC values were 6.25, 6.25 and 100 mg/mL, respectively. Conclusion: Our findings confirmed that extracellular synthesis of AgNPs mediated by E. camaldulensis flowers extract indicated a good bactericidal activity against the tested bacteria and can be used in various fields as an antibacterial agent. Further studies are needed to characterize the toxicity effect of these particles.

  10. Effects of silver nanoparticles on radish sprouts: Root growth reduction and modifications in the nutritional value

    Directory of Open Access Journals (Sweden)

    Nubia eZuverza-Mena

    2016-02-01

    Full Text Available Reports indicate that silver nanoparticles (nAg are toxic to vegetation, but little is known about their effects in crop plants. This study examines the impacts of nAg on the physiology and nutritional quality of radish (Raphanus sativus sprouts. Seeds were germinated and grown for five days in nAg suspensions at 0, 125, 250, and 500 mg/L. Seed germination and seedling growth were evaluated with traditional methodologies; the uptake of Ag and nutrients was quantified by inductively coupled plasma-optical emission spectroscopy (ICP-OES and changes in macromolecules were analyzed by infrared (IR spectroscopy. None of the nAg concentrations reduced seed germination. However, the water content (% of the total weight was reduced by 1.62%, 1.65%, and 2.54% with exposure to 125, 250 and 500 mg/L, respectively, compared with the control. At 500 mg/L, the root and shoot lengths were reduced by 47.7% and 40%, with respect to the control. The seedlings exposed to 500 mg/L had 901±150 mg Ag/kg dry wt and significantly less Ca, Mg, B, Cu, Mn, and Zn, compared with the control. The infrared spectroscopy analysis showed changes in the bands corresponding to lipids (3000 – 2800 cm-1, proteins (1550 - 1530, and structural components of plant cells such as lignin, pectin and cellulose. These results suggest that nAg could significantly affect the growth, nutrient content and macromolecule conformation in radish sprouts, with unknown consequences for human health.

  11. Effect of poly-α, γ, L-glutamic acid as a capping agent on morphology and oxidative stress-dependent toxicity of silver nanoparticles

    Science.gov (United States)

    Stevanović, Magdalena; Kovačević, Branimir; Petković, Jana; Filipič, Metka; Uskoković, Dragan

    2011-01-01

    Highly stable dispersions of nanosized silver particles were synthesized using a straightforward, cost-effective, and ecofriendly method. Nontoxic glucose was utilized as a reducing agent and poly-α, γ, L-glutamic acid (PGA), a naturally occurring anionic polymer, was used as a capping agent to protect the silver nanoparticles from agglomeration and render them biocompatible. Use of ammonia during synthesis was avoided. Our study clearly demonstrates how the concentration of the capping agent plays a major role in determining the dimensions, morphology, and stability, as well as toxicity of a silver colloidal solution. Hence, proper optimization is necessary to develop silver colloids of narrow size distribution. The samples were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurement. MTT assay results indicated good biocompatibility of the PGA-capped silver nanoparticles. Formation of intracellular reactive oxygen species was measured spectrophotometrically using 2,7-dichlorofluorescein diacetate as a fluorescent probe, and it was shown that the PGA-capped silver nanoparticles did not induce intracellular formation of reactive oxygen species. PMID:22131829

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

    Science.gov (United States)

    Lin, Yu-Hsuan; Chen, Kun-Tso; Ho, Jeng-Rong

    2011-06-01

    A method for rapidly fabricating dense and high-aspect-ratio silver nanowires, with wire diameter of 200 nm and wire length more than 30 µm, is reported. The fabrication process simply involves filling the silver nitrate solution into the pores of an anodic-aluminum-oxide (AAO) membrane through capillary attraction and irradiating the dried template AAO membrane using a pulsed ArF excimer laser. Through varying the thickness and pore diameter of the employed AAO membrane, the primary dimensions of the targeted silver nanowires can be plainly specified; and, by amending the initial concentration of the silver nitrate solution and adjusting the laser operation parameters, laser fluence and number of laser pulses, the surface morphology and size of the resulting nanowires can be finely regulated. The wire formation mechanism is considered through two stages: the period of precipitation of silver particles from the dried silver nitrate film through the laser-induced photoreduction; and, the phase of clustering, merging and fusing of the reduced particles to form nanowires in the template pores by the thermal energy owing to photothermal effect. This approach is straightforward and takes the advantage that all the fabrication processes can be executed in an ambient environment and at room temperature. In addition, by the excellence in local processing that the laser possesses, this method is suitable for precisely growing nanowires.

  13. Green synthesis, antimicrobial and cytotoxic effects of silver nanoparticles using Eucalyptus chapmaniana leaves extract.

    Science.gov (United States)

    Sulaiman, Ghassan Mohammad; Mohammed, Wasnaa Hatif; Marzoog, Thorria Radam; Al-Amiery, Ahmed Abdul Amir; Kadhum, Abdul Amir H; Mohamad, Abu Bakar

    2013-01-01

    To synthesize silver nanopaticles from leaves extract of Eucalyptus chapmaniana (E. chapmaniana) and test the antimicrobial of the nanoparticles against different pathogenic bacteria, yeast and its toxicity against human acute promyelocytic leukemia (HL-60) cell line. Ten milliliter of leaves extract was mixed with 90 mL of 0.01 mmol/mL or 0.02 mmol/mL aqueous AgNO3 and exposed to sun light for 1 h. A change from yellowish to reddish brown color was observed. Characterization using UV-vis spectrophotometery and X-ray diffraction analysis were performed. Antimicrobial activity against six microorganisms was tested using well diffusion method and cytoxicity test using 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, a yellow tetrazole was obtained on the human leukemia cell line (HL-60). UV-vis spectral analysis showed silver surface plasmon resonance band at 413 nm. X-ray diffraction showed that the particles were crystalline in nature with face centered cubic structure of the bulk silver with broad beaks at 38.50° and 44.76°. The synthesized silver nanoparticles efficiently inhibited various pathogenic organisms and reduced viability of the HL-60 cells in a dose-dependent manner. It has been demonstrated that the extract of E. chapmaniana leaves are capable of producing silver nanoparticles extracellularly and the Ag nanoparticles are quite stable in solution. Further studies are needed to fully characterize the toxicity and the mechanisms involved with the antimicrobial and anticancer activity of these particles.

  14. Green synthesis,antimicrobial and cytotoxic effects of silver nanoparticles using Eucalyptus chapmaniana leaves extract

    Institute of Scientific and Technical Information of China (English)

    Ghassan; Mohammad; Sulaiman; Wasnaa; Hatif; Mohammed; Thorria; Radam; Marzoog; Ahmed; Abdul; Amir; Al-Amiery; Abdul; Amir; H.Kadhum; Abu; Bakar; Mohamad

    2013-01-01

    Objective:To synthesize silver nanopaticles from leaves extract of Eucalyptus chapmaniana(E.chapmaniana)and test the antimicrobial of the nanoparticles against different pathogenic bacteria,yeast and its toxicity against human acute promyelocytic leukemia(HL-60)cell line.Methods:Ten milliliter of leaves extract was mixed with 90 mL of 0.01 mmol/mL or 0.02 mmol/mL aqueous AgNO3 and exposed to sun light for 1 h.A change from yellowish to reddish brown color was observed.Characterization using UV-vis spectrophotometery and X-ray diffraction analysis were performed.Antimicrobial activity against six microorganisms was tested using well diffusion method and cytoxicity test using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide,a yellow tetrazole was obtained on the human leukemia cell line(HL-60).Results:UV-vis spectral analysis showed silver surface plasmon resonance band at 413 nm.X-ray diffraction showed that the particles were crystalline in nature with face centered cubic structure of the bulk silver with broad beaks at 38.50°and 44.76°.The synthesized silver nanoparticles efficiently inhibited various pathogenic organisms and reduced viability of the HL-60 cells in a dose-dependent manner.Conclusions:It has been demonstrated that the extract of E.chapmaniana leaves are capable of producing silver nanoparticles extracellularly and the Ag nanoparticles are quite stable in solution.Further studies are needed to fully characterize the toxicity and the mechanisms involved with the antimicrobial and anticancer activity of these particles.

  15. Green synthesis, antimicrobial and cytotoxic effects of silver nanoparticles using Eucalyptus chapmaniana leaves extract

    Institute of Scientific and Technical Information of China (English)

    Ghassan Mohammad Sulaiman; Wasnaa Hatif Mohammed; Thorria Radam Marzoog; Ahmed Abdul Amir Al-Amiery; Abdul Amir H Kadhum; Abu Bakar Mohamad

    2013-01-01

    Objective: To synthesize silver nanopaticles from leaves extract of Eucalyptus chapmaniana (E. chapmaniana) and test the antimicrobial of the nanoparticles against different pathogenic bacteria, yeast and its toxicity against human acute promyelocytic leukemia (HL-60) cell line.Methods:Ten milliliter of leaves extract was mixed with 90 mL of 0.01 mmol/mL or 0.02 mmol/mL aqueous AgNO3 and exposed to sun light for 1 h. A change from yellowish to reddish brown color was observed. Characterization using UV-vis spectrophotometery and X-ray diffraction analysis were performed. Antimicrobial activity against six microorganisms was tested using well diffusion method and cytoxicity test using 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, a yellow tetrazole was obtained on the human leukemia cell line (HL-60). Results: UV-vis spectral analysis showed silver surface plasmon resonance band at 413 nm. X-ray diffraction showed that the particles were crystalline in nature with face centered cubic structure of the bulk silver with broad beaks at 38.50 ° and 44.76 °. The synthesized silver nanoparticles efficiently inhibited various pathogenic organisms and reduced viability of the HL-60 cells in a dose-dependent manner. Conclusions: It has been demonstrated that the extract of E. chapmaniana leaves are capable of producing silver nanoparticles extracellularly and the Ag nanoparticles are quite stable in solution. Further studies are needed to fully characterize the toxicity and the mechanisms involved with the antimicrobial and anticancer activity of these particles.

  16. Investigating the Effect of Silver Nanoparticles on E.coli Growth

    Directory of Open Access Journals (Sweden)

    N Naghsh

    2012-07-01

    Full Text Available

    Background and Objectives: Nanoparticles are very small pieces of material that have different applications in medical fields. Nanosilver technology is a functional branch in nanotechnology. Different studies have proved antimicrobial effects and useful functions of nanosilver in biotechnology field and its specific inhibitory effects on microbes. As no exact report about antibacterial effects of these nanoparticles has been made, this study was conducted to investigate silver inhibitory effects on E.coli.

     

    Methods: Nanosilver particles at concentration of 100, 200, 300, 400 and 500ppm were inseminated on blank anti biogram discs and were placed on cultivated nutrient agar environment by 0.5 Mac Farland`s standard. Then, inhibition zone diameter was measured in the first, second, and sixth day. T-test was used to compare the average inhibition zone in control and treatment groups and the value p<0.05 was considered as statistically significant.

     

    Results: In the first day after the treatment of nanosilver particles at a concentration of 400ppm, the average inhibition zone diameter was 2.30±0.43mm in E.coli that has been increased significantly in comparison with control culture (p=0.01. In the second day after treatment at a concentration of 400ppm, the average disc diameter was 2.48±0.39mm which shows that these values have been increased significantly in comparison with control groups (p=0.01, but they were not significantly different from the first day.

     

    Conclusion: Since Nonotechnology has various applications in different fields, expanding these results could be helpful in biomedical therapeutic of bacteria diseases. In conclusion, our results may provide this important insight that nanoparticles could replace many antibiotics without many side effects.

     

  17. The Silver Oxide-Zinc Alkaline Primary Cell. Part 2. Effects of Various Types of Negative Electrodes on Cell Characteristics

    National Research Council Canada - National Science Library

    Shepherd, C. M

    1951-01-01

    ... (generally a potassium hydroxide solution). During discharge, the silver peroxide in the positive electrode is reduced to metallic silver and the metallic zinc in the negative electrode is oxidized either to zinc oxide or to a complex zincate ion...

  18. Effect of radiation resistance additives for insulation materials

    International Nuclear Information System (INIS)

    Yamamoto, Yasuaki; Yagyu, Hideki; Seguchi, Tadao.

    1988-01-01

    For the electric wires and cables used in radiation environment such as nuclear power stations and fuel reprocessing facilities, the properties of excellent radiation resistance are required. For these insulators and sheath materials, ethylene propylene rubber, polyethylene and other polymers have been used, but it cannot be said that they always have good radiation resistance. However, it has been well known that radiation resistance can be improved with small amount of additives, and heat resistance and burning retarding property as well as radiation resistance are given to the insulators of wires and cables for nuclear facilities by mixing various additives. In this research, the measuring method for quantitatively determining the effect of Anti-rad (radiation resistant additive) was examined. Through the measurement of gel fraction, radical formation and decomposed gas generation, the effect of Anti-rad protecting polymers from radiation deterioration was examined from the viewpoint of chemical reaction. The experimental method and the results are reported. The radiation energy for cutting C-H coupling is polymers is dispersed by Anti-rad, and the probability of cutting is lowered. Anti-rad catches and extinguishes radicals that start oxidation reaction. (K.I.)

  19. Evaluation of in vitro antibacterial effect of room curing polymethylmethacrylate material adding nano-silver base inorganic antibacterial agents

    International Nuclear Information System (INIS)

    Jia Chunli; Wang Xiaorong; Zhang Citong; Sun Shiqun; Yang Yun

    2012-01-01

    Objective: To investigate the antibacterial effect of room curing polymethylmethacrylate (PMMA) material adding nano-silver base inorganic antibacterial agent and to detect the changes of its mechanical property. Methods: Nano-silver base inorganic antibacterial agent was added to the room curing PMMA material in the range of 0.5% -3.0% at an interval of 0.5% by ball milling specimen. Antibacterial rates of the specimens were detected by film method. Bending strength, impact strength, and wear resistance of the specimens were respectively detected on electronic universal testing machine, impact test machine and friction and wear test machine. Results: The antibacterial rates of Streptococcus mutans and Candida albicans were more than 50% when antibiotics content was 1.0% . The antibacterial rates of Streptococcus mutans and Candida albicans were more than 90% when the antibiotics content was 2.5% . The three mechanical properties were increased compared with control group when the antibacterial agents were in the range of 1.0% -1.5% . Then the three mechanical properties were decreased with the increasing of antimicrobial concentration. When the antibiotics content was 2.0% , the wear resistance had significant difference compared with control group (P<0.05); when the antibiotics content was 2.5% , the bending strength and impact strength had significant difference compared with control group (P<0.05). Conclusion: The antibacterial effect of room curing PMMA adding nano-silver base inorganic antibacterial agent is ideal. The antibacterial rate is increased gradually with the increasing content of antibacterial agents. There is no significant effect on the mechanical properties of room curing PMMA material, but the antibacterial effects are satisfied when the content of antibacterial agents is 2.0% . (authors)

  20. Catalytic effect of halide additives ball milled with magnesium hydride

    Energy Technology Data Exchange (ETDEWEB)

    Malka, I.E.; Bystrzycki, J. [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); Czujko, T. [Department of Advanced Materials and Technologies, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); CanmetENERGY, Hydrogen Fuel Cells and Transportation Energy, Natural Resources (Canada)

    2010-02-15

    The influence of various halide additives milled with magnesium hydride (MgH{sub 2}) on its decomposition temperature was studied. The optimum amount of halide additive and milling conditions were evaluated. The MgH{sub 2} decomposition temperature and energy of activation reduction were measured by temperature programmed desorption (TPD) and differential scanning calorimetry (DSC). The difference in catalytic efficiency between chlorides and fluorides of the various metals studied is presented. The effects of oxidation state, valence and position in the periodic table for selected halides on MgH{sub 2} decomposition temperature were also studied. The best catalysts, from the halides studied, for magnesium hydride decomposition were ZrF{sub 4}, TaF{sub 5}, NbF{sub 5}, VCl{sub 3} and TiCl{sub 3}. (author)

  1. Augmenting Phase Space Quantization to Introduce Additional Physical Effects

    Science.gov (United States)

    Robbins, Matthew P. G.

    Quantum mechanics can be done using classical phase space functions and a star product. The state of the system is described by a quasi-probability distribution. A classical system can be quantized in phase space in different ways with different quasi-probability distributions and star products. A transition differential operator relates different phase space quantizations. The objective of this thesis is to introduce additional physical effects into the process of quantization by using the transition operator. As prototypical examples, we first look at the coarse-graining of the Wigner function and the damped simple harmonic oscillator. By generalizing the transition operator and star product to also be functions of the position and momentum, we show that additional physical features beyond damping and coarse-graining can be introduced into a quantum system, including the generalized uncertainty principle of quantum gravity phenomenology, driving forces, and decoherence.

  2. Strong and Nonspecific Synergistic Antibacterial Efficiency of Antibiotics Combined with Silver Nanoparticles at Very Low Concentrations Showing No Cytotoxic Effect.

    Science.gov (United States)

    Panáček, Aleš; Smékalová, Monika; Kilianová, Martina; Prucek, Robert; Bogdanová, Kateřina; Večeřová, Renata; Kolář, Milan; Havrdová, Markéta; Płaza, Grażyna Anna; Chojniak, Joanna; Zbořil, Radek; Kvítek, Libor

    2015-12-28

    The resistance of bacteria towards traditional antibiotics currently constitutes one of the most important health care issues with serious negative impacts in practice. Overcoming this issue can be achieved by using antibacterial agents with multimode antibacterial action. Silver nano-particles (AgNPs) are one of the well-known antibacterial substances showing such multimode antibacterial action. Therefore, AgNPs are suitable candidates for use in combinations with traditional antibiotics in order to improve their antibacterial action. In this work, a systematic study quantifying the synergistic effects of antibiotics with different modes of action and different chemical structures in combination with AgNPs against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus was performed. Employing the microdilution method as more suitable and reliable than the disc diffusion method, strong synergistic effects were shown for all tested antibiotics combined with AgNPs at very low concentrations of both antibiotics and AgNPs. No trends were observed for synergistic effects of antibiotics with different modes of action and different chemical structures in combination with AgNPs, indicating non-specific synergistic effects. Moreover, a very low amount of silver is needed for effective antibacterial action of the antibiotics, which represents an important finding for potential medical applications due to the negligible cytotoxic effect of AgNPs towards human cells at these concentration levels.

  3. Tuning silver ion release properties in reactively sputtered Ag/TiOx nanocomposites

    Science.gov (United States)

    Xiong, J.; Ghori, M. Z.; Henkel, B.; Strunskus, T.; Schürmann, U.; Deng, M.; Kienle, L.; Faupel, F.

    2017-07-01

    Silver/titania nanocomposites with strong bactericidal effects and good biocompatibility/environmental safety show a high potential for antibacterial applications. Tailoring the silver ion release is thus highly promising to optimize the antibacterial properties of such coatings and to preserve biocompatibility. Reactive sputtering is a fast and versatile method for the preparation of such Ag/TiOx nanocomposites coatings. The present work is concerned with the influence of sputter parameters on the surface morphology and silver ion release properties of reactively sputtered Ag/TiOx nanocomposites coatings showing a silver nanoparticle size distribution in the range from 1 to 20 nm. It is shown that the silver ion release rate strongly depends on the total pressure: the coatings prepared at lower pressure present a lower but long-lasting release behavior. The much denser structure produced under these conditions reduces the transport of water molecules into the coating. In addition, the influence of microstructure and thickness of titanium oxide barriers on the silver ion release were investigated intensively. Moreover, for the coatings prepared at high total pressure, it was demonstrated that stable and long-lasting silver release can be achieved by depositing a barrier with a high rate. Nanocomposites produced under these conditions show well controllable silver ion release properties for applications as antibacterial coatings.

  4. Versatility of cooperative transcriptional activation: a thermodynamical modeling analysis for greater-than-additive and less-than-additive effects.

    Directory of Open Access Journals (Sweden)

    Till D Frank

    Full Text Available We derive a statistical model of transcriptional activation using equilibrium thermodynamics of chemical reactions. We examine to what extent this statistical model predicts synergy effects of cooperative activation of gene expression. We determine parameter domains in which greater-than-additive and less-than-additive effects are predicted for cooperative regulation by two activators. We show that the statistical approach can be used to identify different causes of synergistic greater-than-additive effects: nonlinearities of the thermostatistical transcriptional machinery and three-body interactions between RNA polymerase and two activators. In particular, our model-based analysis suggests that at low transcription factor concentrations cooperative activation cannot yield synergistic greater-than-additive effects, i.e., DNA transcription can only exhibit less-than-additive effects. Accordingly, transcriptional activity turns from synergistic greater-than-additive responses at relatively high transcription factor concentrations into less-than-additive responses at relatively low concentrations. In addition, two types of re-entrant phenomena are predicted. First, our analysis predicts that under particular circumstances transcriptional activity will feature a sequence of less-than-additive, greater-than-additive, and eventually less-than-additive effects when for fixed activator concentrations the regulatory impact of activators on the binding of RNA polymerase to the promoter increases from weak, to moderate, to strong. Second, for appropriate promoter conditions when activator concentrations are increased then the aforementioned re-entrant sequence of less-than-additive, greater-than-additive, and less-than-additive effects is predicted as well. Finally, our model-based analysis suggests that even for weak activators that individually induce only negligible increases in promoter activity, promoter activity can exhibit greater-than-additive

  5. Additive effects of acetic acid upon hydrothermal reaction of amylopectin

    International Nuclear Information System (INIS)

    Sugano, Motoyuki; Katoh, Harumi; Komatsu, Akihiro; Kobayashi, Hiroshi; Okado, Kohta; Kakuta, Yusuke; Hirano, Katsumi

    2012-01-01

    It is well known that over 0.8 kg kg −1 of starch is consisted of amylopectin (AP). In this study, production of glucose for raw material of ethanol by hydrothermal reaction of AP as one of the model compound of food is discussed. Further, additive effects of acetic acid upon hydrothermal reactions of AP are also investigated. During hydrothermal reaction of AP, production of glucose occurred above 453 K, and the glucose yield increased to 0.48 kg kg −1 at 473 K. Upon hydrothermal reaction of AP at 473 K, prolongation of the holding time was not effective for the increase of the glucose yield. Upon hydrothermal reaction of AP at 473 K for 0 s, the glucose yield increased significantly by addition between 0.26 mol L −1 and 0.52 mol L −1 of acetic acid. However, the glucose yield decreased and the yield of the other constituents increased with the increases of concentration of acetic acid from 0.65 mol L −1 to 3.33 mol L −1 . It was considered that hydrolysis of AP to yield glucose was enhanced due to the increase of the amount of proton derived from acetic acid during hydrothermal reaction with 0.52 mol L −1 of acetic acid. -- Highlights: ► Glucose production by hydrothermal reaction of amylopectin (AP) at 473 K. ► Glucose yield increased to 0.48 kg kg -1 at 473 K. ► Prolongation of holding time was not effective for glucose yield. ► Glucose yield increased significantly by acetic acid (0.26–0.52 mol L-1) addition. ► Hydrolysis of AP to glucose was enhanced due to increase of proton from acetic acid.

  6. Effects of silver nanoparticles and ions on a co-culture model for the gastrointestinal epithelium.

    Science.gov (United States)

    Georgantzopoulou, Anastasia; Serchi, Tommaso; Cambier, Sébastien; Leclercq, Céline C; Renaut, Jenny; Shao, Jia; Kruszewski, Marcin; Lentzen, Esther; Grysan, Patrick; Eswara, Santhana; Audinot, Jean-Nicolas; Contal, Servane; Ziebel, Johanna; Guignard, Cédric; Hoffmann, Lucien; Murk, AlberTinka J; Gutleb, Arno C

    2016-02-17

    The increased incorporation of silver nanoparticles (Ag NPs) into consumer products makes the characterization of potential risk for humans and other organisms essential. The oral route is an important uptake route for NPs, therefore the study of the gastrointestinal tract in respect to NP uptake and toxicity is very timely. The aim of the present study was to evaluate the effects of Ag NPs and ions on a Caco-2/TC7:HT29-MTX intestinal co-culture model with mucus secretion, which constitutes an important protective barrier to exogenous agents in vivo and may strongly influence particle uptake. The presence of the mucus layer was confirmed with staining techniques (alcian blue and toluidine blue). Mono and co-cultures of Caco-2/TC7 and HT29-MTX cells were exposed to Ag NPs (Ag 20 and 200 nm) and AgNO3 and viability (alamar blue), ROS induction (DCFH-DA assay) and IL-8 release (ELISA) were measured. The particle agglomeration in the media was evaluated with DLS and the ion release with ultrafiltration and ICP-MS. The effects of the Ag NPs and AgNO3 on cells in co-culture were studied at a proteome level with two-dimensional difference in gel electrophoresis (2D-DIGE) followed by Matrix Assisted Laser Desorption Ionization - Time Of Flight/ Time Of Flight (MALDI-TOF/TOF) mass spectrometry (MS). Intracellular localization was assessed with NanoSIMS and TEM. The presence of mucus layer led to protection against ROS and decrease in IL-8 release. Both Ag 20 and 200 nm NPs were taken up by the cells and Ag NPs 20 nm were mainly localized in organelles with high sulfur content. A dose- and size-dependent increase in IL-8 release was observed with a lack of cytotoxicity and oxidative stress. Sixty one differentially abundant proteins were identified involved in cytoskeleton arrangement and cell cycle, oxidative stress, apoptosis, metabolism/detoxification and stress. The presence of mucus layer had an impact on modulating the induced toxicity of NPs. NP-specific effects were

  7. Stability of single dispersed silver nanoparticles in natural and synthetic freshwaters: Effects of dissolved oxygen.

    Science.gov (United States)

    Zou, Xiaoyan; Li, Penghui; Lou, Jie; Fu, Xiaoyan; Zhang, Hongwu

    2017-11-01

    Silver nanoparticles (AgNPs) are increasingly used in various commercial products. This increased use raises ecological concerns because of the large release of AgNPs into the environment. Once released, the local water chemistry has the potential to influence the environmental fates and behaviors of AgNPs. The impacts of dissolved oxygen and natural organic matter (NOM) on the dissolution and stability of AgNPs were investigated in synthetic and natural freshwaters for 7 days. In synthetic freshwater, the aggregation of AgNPs occurred due to the compression of the electric double layer, accompanied by the dissolution of AgNPs. However, once oxygen was removed, the highest dissolved Ag (Ag dis ) concentration decreased from 356.5 μg/L to 272.1 μg/L, the pH of the AgNP suspensions increased from less than 7.6 to more than 8.4, and AgNPs were regenerated by the reduction of released Ag + by citrate. The addition of NOM mitigated aggregation, inhibited oxidative dissolution and induced the transformation of AgNPs into Ag 2 S due to the formation of NOM-adsorbed layers, the reduction of Ag + by NOM, and the high affinity of sulfur-enriched species in NOM for Ag. Likewise, in oxygen-depleted natural freshwaters, the inhibition of oxidative dissolution was obtained in comparison with oxygenated freshwaters, showing a decrease in the maximum Ag dis concentration from 137.6 and 57.0 μg/L to 83.3 and 42.4 μg/L from two natural freshwater sites. Our results suggested that aggregation and dissolution of AgNPs in aquatic environments depend on the chemical composition, where oxygen-depleted freshwaters more significantly increase the colloidal stability. In comparison with oxic conditions, anoxic conditions were more favorable to the regeneration of AgNPs by reducing species (e.g., citrate and NOM) and enhanced the stability of nanoparticles. This indicates that some AgNPs will be more stable for long periods in oxygen-deprived freshwaters, and pose more serious

  8. Priming effects in Haplic Luvisol after different substrate additions

    Science.gov (United States)

    Bogomolova, I.; Blagodatskaya, E.; Blagodatsky, S.; Kuzyakov, Y.

    2009-04-01

    Although soils contain considerable amounts of soil organic carbon (SOC), most of it is not easily available for microorganisms. Addition of various substrates to soil (for example, plant residues, root exudates) may affect SOC mineralization. The addition of mineral nutrients, especially N, may also affect C turnover and so change the mineralization rate of SOC. Such short-term changes in mineralization of organic substance of soil were termed as "priming-effects" (Bingemann et al., 1953). Priming effect leads to additional mineralization of SOC (van Elsas and van Overbeek, 1993). It has been shown that not only plant residues induce priming effects (Sauerbeck, 1966; Stemmer et al., 1999; Bell et al., 2003), but also easily available substrates such as sugars or amino acids, which are present in soil solutions and root exudates (Vasconcellos, 1994; Shen and Bartha, 1997; Hamer and Marschner, 2002). Since easily available substrates may not only accelerate SOC mineralization, but also may retard it, Kuzyakov et al. (2000) differentiated between positive and negative priming effects. It is not clear until now, how long priming effects persists in soil after substrate addition, and if they are induced every time when a substrate becomes available in soil. So, the aim of this study was to evaluate effects of glucose and plant residues on SOM decomposition, and influence of glucose on plant residues decomposition in soil. The experimental layout was designed as two factor experiment: 1) plant residues and 2) available substrate amendment. Maize shoot residues (50 mg added to 5 g soil) were 14C labeled (9•104 DPM per 5 g soil). Soil without of any plant residues served as a control for this treatment. Two levels of D (+) glucose as easily available substrates were added after three months of pre-incubation of soil samples with maize residues: 0.009 mg glucose C g-1 soil and 0.225 mg glucose C g-1 soil. The glucose was uniformly labelled with 14C (2.37•104 DPM per 5

  9. Effect of nanosecond UV laser irradiation on luminescence and absorption in silver- and copper-containing phosphate glasses

    Science.gov (United States)

    Murashov, A. A.; Sidorov, A. I.; Stoliarchuk, M. V.

    2018-03-01

    Experimental evidence is presented that nanosecond UV laser irradiation of silver- and copper-containing barium phosphate glasses leads to luminescence quenching in the visible range. Subsequent heat treatment induces an absorption in the range 350–500 nm. These effects are due to the ionisation and fragmentation of subnanometre molecular clusters by laser radiation and subsequent (heat treatment-induced) formation of nanoparticles possessing plasmon resonance. Our numerical modelling results demonstrate the feasibility of producing stable AgnCum hybrid molecular clusters in glass. Local modification of the optical properties of glass by laser light can be used for optical information recording.

  10. A comparative study to evaluate the effect of honey dressing and silver sulfadiazene dressing on wound healing in burn patients

    OpenAIRE

    Baghel, P. S.; Shukla, S.; Mathur, R. K.; Randa, R.

    2009-01-01

    To compare the effect of honey dressing and silver-sulfadiazene (SSD) dressing on wound healing in burn patients. Patients (n=78) of both sexes, with age group between 10 and 50 years and with first and second degree of burn of less than 50% of TBSA (Total body surface area) were included in the study, over a period of 2 years (2006-08). After stabilization, patients were randomly attributed into two groups: ?honey group? and ?SSD group?. Time elapsed since burn was recorded. After washing wi...

  11. Eddy damping effect of additional conductors in superconducting levitation systems

    Science.gov (United States)

    Jiang, Zhao-Fei; Gou, Xiao-Fan

    2015-12-01

    Passive superconducting levitation systems consisting of a high temperature superconductor (HTSC) and a permanent magnet (PM) have demonstrated several fascinating applications such as the maglev system, flywheel energy storage. Generally, for the HTSC-PM levitation system, the HTSC with higher critical current density Jc can obtain larger magnetic force to make the PM levitate over the HTSC (or suspended below the HTSC), however, the process of the vibration of the levitated PM, provides very limited inherent damping (essentially hysteresis). To improve the dynamic stability of the levitated PM, eddy damping of additional conductors can be considered as the most simple and effective approach. In this article, for the HTSC-PM levitation system with an additional copper damper attached to the HTSC, we numerically and comprehensively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. Furthermore, we comparatively studied four different arrangements of the copper damper, on the comprehensive analyzed the damping effect, efficiency (defined by c/VCu, in which VCu is the volume of the damper) and Joule heating, and finally presented the most advisable arrangement.

  12. Antibacterial and cytotoxic effect of biologically synthesized silver nanoparticles using aqueous root extract of Erythrina indica lam

    Science.gov (United States)

    Rathi Sre, P. R.; Reka, M.; Poovazhagi, R.; Arul Kumar, M.; Murugesan, K.

    2015-01-01

    Simple, yet an effective and rapid approach for the green synthesis of silver nanoparticles (Ag NPs) using root extract of Erythrina indica and its in vitro antibacterial activity was tried against human pathogenic bacteria and its cytotoxic effect in breast and lung cancer cell lines has been demonstrated in this study. Various instrumental techniques were adopted to characterize the synthesized Ag NPs viz. UV-Vis (Ultra violet), FTIR (Fourier Transform Infrared), XRD (X-ray diffraction), DLS (Dynamic light scattering), HR TEM (High-resolution transmission electron microscopy), EDX (Energy-dispersive X-ray spectroscopy). Surface plasmon spectra for Ag NPs are centered nearly at 438 nm with dark brown color. FTIR analysis revealed the presence of terpenes, phenol, flavonols and tannin act as effective reducing and capping agents for converting silver nitrate to Ag NPs. The synthesized Ag NPs were found to be spherical in shape with size in the range of 20-118 nm. Moreover, the synthesized Ag NPs showed potent antibacterial activity against Gram positive and Gram negative bacteria and these biologically synthesized nanoparticles were also proved to exhibit excellent cytotoxic effect on breast and lung cancer cell lines.

  13. The effect of microbial inocula on the growth of black locust, Siberian elm and silver maple seedlings

    Directory of Open Access Journals (Sweden)

    Hajnal-Jafari Timea

    2014-01-01

    Full Text Available Growth and development of forest plants depend mostly on the soil microbial activity since no mineral or organic fertilizers are applied. Microbial processes can be activated and conditions for plants development improved with the introduction of selected microorganisms in the soil. With the aim of obtaining quality planting material in a shorter period of time, the effects of Azotobacter chroococcum and Streptomyces sp. on the early growth of black locust (Robinia pseudoacacia, Siberian elm (Ulmus pumila and silver-leaf maple (Acer dasycarpum were investigated in this study. Microorganisms were applied individually and in a mixture (1:1. Plant height was measured on the 90th, 120th and 180th day after planting. Plant diameter, as well as the number of actinomycetes and azotobacters was measured at the end of the vegetation period (180 days after planting. Applied microorganisms had a positive effect on the seedling height in all three plant species, with the best effect found in the black locust. Effectiveness of applied microorganisms on seedling diameter was the highest in the silver-leaf maple. The largest number of azotobacters was found in the rhizosphere of black locust. Number of microorganisms from both groups was increased in the inoculated variants. [Projekat Ministarstva nauke Republike Srbije, br. III 43002

  14. Investigation of ageing effects on the electrical properties of polyaniline/silver nanocomposites

    International Nuclear Information System (INIS)

    Afzal, Asma Binat; Akhtar, Muhammad Javed

    2011-01-01

    Polyaniline(PANI)/Ag nanocomposites, synthesized by incorporation of separately prepared silver nanoparticles in 1-methyl-2-pyrrolidinone(NMP) solution of PANI, have been aged at the accelerated temperature of 120 °C to simulate a storage period of 2 years at 25 °C. The accelerated ageing of these materials is done by using the activation energy calculated from data collected using heat flow calorimetry (HFC). The impedance spectroscopic studies of NMP plasticized aged nanocomposite films suggest a microphase separation into reduced and oxidized repeat units. There is crosslinking of the PANI films during ageing thereby obstructing the charge transfer between PANI chains and silver nanoparticles. As a result, the resistivity is increased. (interdisciplinary physics and related areas of science and technology)

  15. Rapid, green synthesis and surface-enhanced Raman scattering effect of single-crystal silver nanocubes

    Science.gov (United States)

    Mao, Aiqin; Jin, Xia; Gu, Xiaolong; Wei, Xiaoqing; Yang, Guojing

    2012-08-01

    Single-crystal silver (Ag) nanocubes have been synthesized by a rapid and green method at room temperature by adding sodium hydroxide solution to the mixed solutions of silver nitrate, glucose and polyvinylpyrrolidone (PVP). The X-ray diffraction (XRD), ultraviolet-visible (UV-visible) and transmission electron microscopy (TEM) were used to characterize the phase composition and morphology. The results showed that the as-prepared particles were single-crystal Ag nanocubes with edge lengths of around 77 nm and a growing direction along {1 0 0} facets. As substrates for surface-enhanced Raman scattering (SERS) experiment on crystal violet (CV), the SERS enhancement factor of the as-prepared Ag nanocubes were measured to be 5.5 × 104, indicating potential applications in chemical and biological analysis.

  16. Models for mass transfer effects in semi-fuel cells and for a silver-zinc battery

    Science.gov (United States)

    Venkatraman, Murali Sankar

    Semi-Fuel Cells (SFCs) and Silver-Zinc batteries have been recognized as batteries for high power applications. For channel flow between two parallel plates, featured in SFCs, obstacles may take the form of ordered asymmetrical porous nets. The net controls the spacing between the two electrode plates. The effect of the inert insulating net and its geometry on the heat and mass transfer characteristics in such a system is presented. The governing equations for momentum, continuity, and energy are solved in a three-dimensional domain using a commercial computational fluid dynamics software for fully developed flow with constant temperature boundary conditions. The local Nusselt number is calculated from the resulting temperature distribution. This net also affects the limiting current distribution in an SFC operating at limiting current because it disrupts the parabolic laminar flow velocity distribution. Hence, the current density distribution is obtained from the Nusselt number distribution through a heat and mass transfer analogy. The location, spacing, and number of the longitudinal and transverse ribs of the net are shown to affect the local and average current density distributions and Nusselt numbers on each of the two electrode plates. The results show that transverse ribs have a greater effect and that the enhancements of the average current density of 250% can be obtained for a spacing of 0.94 x 10-3 m with greater than 16 transverse ribs. A silver-zinc battery shows similar mass transfer limitations while discharged at moderate to high discharge rates. A one-dimensional mathematical model consisting of a negative (zinc) electrode, separator, and positive (silver) electrode, has been developed to study the performance and thermal behavior of the silver-zinc cell during discharge. The physical phenomena described here are reaction kinetics, mass transfer and heat generation. The analysis includes finite matrix conductivities (thermal and electrical

  17. Effect of silver nanoparticles on the spectral luminescent properties of a gelatin film

    International Nuclear Information System (INIS)

    Ehfendiev, T.Sh.; Kruchenok, Yu.V.; Rubinov, A.N.

    2013-01-01

    We studied the absorption and fluorescence spectra of a rhodamine 6G-activated gelatin film of thickness 10 μm, with and without silver nanoparticles.We observed that doping the film with nanoparticles of diameter 5 nm leads to an increase in the intensity of the absorption spectrum by a factor of 1.17 and its short-wavelength shift (~1.5 nm), while the intensity of the fluorescence spectrum increases by a factor of ~2. (author)

  18. Effect of silver nanoparticles on the spectral luminescent properties of a gelatin film

    Science.gov (United States)

    Efendiev, T. Sh.; Kruchenok, J. V.; Rubinov, A. N.

    2013-03-01

    We studied the absorption and fluorescence spectra of a rhodamine 6G-activated gelatin film of thickness 10 μm, with and without silver nanoparticles. We observed that doping the film with nanoparticles of diameter 5 nm leads to an increase in the intensity of the absorption spectrum by a factor of 1.17 and its short-wavelength shift (~1.5 nm), while the intensity of the fluorescence spectrum increases by a factor of ~2.

  19. The effect of inclination angle on the plastic deformation behavior of bicrystalline silver nanowires with Σ3 asymmetric tilt grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Lin, E-mail: yuanlin@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); National Key Laboratory for Precision Hot Processing of Metals, Harbin 150001 (China); Jing, Peng; Shan, Debin; Guo, Bin [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); National Key Laboratory for Precision Hot Processing of Metals, Harbin 150001 (China)

    2017-01-15

    Atomistic simulations were used to investigate the plastic deformation behavior of bicrystalline silver nanowires with Σ3 asymmetric tilt grain boundaries at 0.1 K. The calculated grain boundary energies of Σ3 asymmetric tilt grain boundaries corresponded well with the energies measured in experiments and predicted by the theoretical description. The Σ3 asymmetric tilt grain boundaries with low inclination angles were composed of a replication of twin boundary segments separated by small ledges. The results demonstrated that the combination effect of Schmid factor and non-Schmid factors could explain dislocations emission into grain 1 only in models with low inclination angles (< 64.76°). At the latter stage of plastic deformation, free surfaces served as additional dislocation sources. Parallelly arranged operative slip systems were the fundamental features of plastic deformation. In addition, a number of stacking faults and multiple stacking faults were formed during plastic deformation. The hindrance of stacking faults to dislocation motion and the interactions between dislocations leaded to the observed strain hardening in nanowires with inclination angles at and above 29.50°. The low stacking fault energy of silver was responsible for the appearance of strain hardening. Dislocations emitted from grain 2 interacted with each other contributing to the observed strain hardening. Grain boundaries were completely eliminated by successive emission of dislocations from grain boundaries in nanowires with an inclination angle of 35.26° and 54.74°. A detailed understanding of the relationship between strength and grain boundary structures as well as specific plastic deformation would push forward the application of nanocrystalline materials and provide insights into the synthesis of nanocrystalline materials with superior strength and ductility.

  20. Thermal processing of EVA encapsulants and effects of formulation additives

    Energy Technology Data Exchange (ETDEWEB)

    Pern, F.J.; Glick, S.H. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores, in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as formulated EVA films, A9918P and 15295P, and solution-cast films of Elvaxrm (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugard P{trademark}, used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155{degrees}C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.

  1. Effect of silver-loaded PMMA on Streptococcus mutans in a drip flow reactor.

    Science.gov (United States)

    Williams, Dustin L; Epperson, Richard Tyler; DeGrauw, Jeffery P; Nielsen, Mattias B; Taylor, Nicholas B; Jolley, Ryan D

    2017-09-01

    Orthodontic retention has been proposed as a life-long commitment for patients who desire to maintain straight teeth. However, the presence of foreign material increases risk of bacterial colonization and caries formation, of which Streptococcus mutans is a key contributor. Multiple studies have assessed the ability of silver to be added to base plate material and resist attachment of S. mutans. However, it does not appear that long-term washout in connection with biofilm growth under physiologically relevant conditions has been taken into consideration. In this study, silver was added to base plate material and exposed to short- or long-term washout periods. Materials were then assessed for their ability to resist biofilm formation of S. mutans using a drip flow reactor that modeled the human oral environment. Data indicated that silver was able to resist biofilm formation following short-term washout, but long-term washout periods resulted in a lack of ability to resist biofilm formation. These data will be important for future development of base plate materials to achieve long-term antimicrobial efficacy to reduce risk of caries formation and benefit patients in the long term. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2632-2639, 2017. © 2017 Wiley Periodicals, Inc.

  2. Effect of Gold on the Microstructural Evolution and Integrity of a Sintered Silver Joint

    Science.gov (United States)

    Muralidharan, Govindarajan; Leonard, Donovan N.; Meyer, Harry M.

    2017-07-01

    There is a need for next-generation, high-performance power electronic packages and systems employing wide-bandgap devices to operate at high temperatures in automotive and electric grid applications. Sintered silver joints are currently being evaluated as an alternative to Pb-free solder joints. Of particular interest is the development of joints based on silver paste consisting of nano- or micron-scale particles that can be processed without application of external pressure. The microstructural evolution at the interface of a pressureless-sintered silver joint formed between a SiC die with Ti/Ni/Au metallization and an active metal brazed (AMB) substrate with Ag metallization at 250°C has been evaluated using scanning electron microscopy (SEM), x-ray microanalysis, and x-ray photoelectron spectroscopy (XPS). Results from focused ion beam (FIB) cross-sections show that, during sintering, pores in the sintered region near to the Au layer tend to be narrow and elongated with long axis oriented parallel to the interface. Further densification results in formation of many small, relatively equiaxed pores aligned parallel to the interface, creating a path for easy crack propagation. X-ray microanalysis results confirm interdiffusion between Au and Ag and that a region with poor mechanical strength is formed at the edge of this region of interdiffusion.

  3. Eddy damping effect of additional conductors in superconducting levitation systems

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Zhao-Fei; Gou, Xiao-Fan, E-mail: xfgou@hhu.edu.cn

    2015-12-15

    Highlights: • In this article, for the eddy current damper attached to the HTSC, we • quantitatively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. • presented four different arrangements of the copper damper, and comparatively studied their damping effects and Joule heating, and finally proposed the most advisable arrangement. - Abstract: Passive superconducting levitation systems consisting of a high temperature superconductor (HTSC) and a permanent magnet (PM) have demonstrated several fascinating applications such as the maglev system, flywheel energy storage. Generally, for the HTSC–PM levitation system, the HTSC with higher critical current density J{sub c} can obtain larger magnetic force to make the PM levitate over the HTSC (or suspended below the HTSC), however, the process of the vibration of the levitated PM, provides very limited inherent damping (essentially hysteresis). To improve the dynamic stability of the levitated PM, eddy damping of additional conductors can be considered as the most simple and effective approach. In this article, for the HTSC–PM levitation system with an additional copper damper attached to the HTSC, we numerically and comprehensively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. Furthermore, we comparatively studied four different arrangements of the copper damper, on the comprehensive analyzed the damping effect, efficiency (defined by c/V{sub Cu}, in which V{sub Cu} is the volume of the damper) and Joule heating, and finally presented the most advisable arrangement.

  4. Physiological effects of some synthetic food colouring additives on rats.

    Science.gov (United States)

    Aboel-Zahab, H; el-Khyat, Z; Sidhom, G; Awadallah, R; Abdel-al, W; Mahdy, K

    1997-11-01

    Three different synthetic chocolate colourant agents (A, B and C) were administered to healthy adult male albino rats for 30 and 60 day periods to evaluate their effects on body weight, blood picture, liver and kidney functions, blood glucose, serum and liver lipids, liver nucleic acids (DNA and RNA), thyroid hormones (T3 and T4) and growth hormone. In addition, histopathological examinations of liver, kidney and stomach sections were studied. These parameters were also investigated 30 days after colourant stoppage (post effect). Ingestion of colourant C (brown HT and indigocarmine) significantly decreased rat body weight, serum cholesterol and HDL-cholesterol fraction, while, T4 hormone, liver RNA content, liver enzymes (S. GOT, S. GPT and alkaline phosphatase), total protein and globulin fractions were significantly elevated. Significant increases were observed in serum total lipids, cholesterol, triglycerides, total protein, globulin and serum transaminases in rats whose diets were supplemented with chocolate colours A and B (sunset yellow, tartrazine, carmoisine and brilliant blue in varying concentrations). Haematological investigations demonstrated selective neutropenia and lymphocytosis with no significant alterations of total white blood cell counts in all rat groups, while haemoglobin concentrations and red blood cell counts were significantly decreased in the rats who were administered food additives A and B. Eosinophilia was noted in rats fed on colourant A only. No changes were recorded for blood glucose, growth hormone and kidney function tests. Histopathological studies showed brown pigment deposition in the portal tracts and Van Küpffer cells of the liver as well as in the interstitial tissue and renal tubular cells of the kidney mainly induced by colourant A. Congested blood vessels and areas of haemorrhage in both liver and renal sections were revealed in those rats who were given colourants B and C. There were no-untoward-effects recorded in the

  5. Pharmacological and toxicological effects of co-exposure of human gingival fibroblasts to silver nanoparticles and sodium fluoride

    Directory of Open Access Journals (Sweden)

    Inkielewicz-Stepniak I

    2014-04-01

    Full Text Available Iwona Inkielewicz-Stepniak,1,* Maria Jose Santos-Martinez,2–4,* Carlos Medina,2,4 Marek W Radomski2,41Department of Medicinal Chemistry, Medical University Gdansk, Debinki, Poland; 2The School of Pharmacy and Pharmaceutical Sciences, Panoz Institute, Trinity College Dublin, Dublin, Ireland; 3School of Medicine, Trinity College Dublin, Dublin, Ireland; 4Trinity Biomedical Sciences Institute, Trinity College, Dublin, Ireland*These authors contributed equally to this workBackground: Silver nanoparticles (AgNPs and fluoride (F are pharmacological agents widely used in oral medicine and dental practice due to their anti-microbial/anti-cavity properties. However, risks associated with the co-exposure of local cells and tissues to these xenobiotics are not clear. Therefore, we have evaluated the effects of AgNPs and F co-exposure on human gingival fibroblast cells.Methods: Human gingival fibroblast cells (CRL-2014 were exposed to AgNPs and/or F at different concentrations for up to 24 hours. Cellular uptake of AgNPs was examined by transmission electron microscopy. Downstream inflammatory effects and oxidative stress were measured by real-time quantitative polymerase chain reaction (PCR and reactive oxygen species (ROS generation. Cytotoxicity and apoptosis were measured by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay and real-time quantitative PCR and flow cytometry, respectively. Finally, the involvement of mitogen-activated protein kinases (MAPK was studied using Western blot.Results: We found that AgNPs penetrated the cell membrane and localized inside the mitochondria. Co-incubation experiments resulted in increased oxidative stress, inflammation, and apoptosis. In addition, we found that co-exposure to both xenobiotics phosphorylated MAPK, particularly p42/44 MAPK.Conclusion: A combined exposure of human fibroblasts to AgNPs and F results in increased cellular damage. Further studies are needed in order to evaluate

  6. Effect of silver-supported materials on the mechanical and antibacterial properties of reinforced acrylic resin composites

    International Nuclear Information System (INIS)

    Han, Zhihui; Zhu, Bangshang; Chen, Rongrong; Huang, Zhuoli; Zhu, Cailian; Zhang, Xiuyin

    2015-01-01

    Highlights: • The novel Novaron-nano-ZrO 2 –ABW/PMMA composites was synthesized. • Nano-ZrO 2 and ABWs could increase the mechanical behavior of this composites. • Novaron had synergistic effect to improve the composites mechanical property and the 4 wt% was the optimal proportion. • Novaron could improve the antibacterial properties through their direct contact with the bacteria. • The composites did not have an adverse affect on cell viability. - Abstract: The aim of this study was to investigate the effect of silver-supported material (Novaron (N)) in acrylic resin (poly(methyl methacrylate) (PMMA)) composites, which reinforced with zirconium dioxide nanoparticles (nano-ZrO 2 ) and aluminum borate whiskers (ABWs), on the mechanical behavior, antibacterial properties and cytotoxicity. Silanized ABWs (4 wt%) and nano-ZrO 2 (2 wt%) were mixed with PMMA powder to obtain nano-ZrO 2 –ABW/PMMA matrices. Various amounts of Novaron particles were incorporated into the matrices and the pure PMMA to test the flexural strength. In addition, Streptococcus mutans (S. mutans) and Canidia albicans (C. albicans) biofilms on the specimen surface and in the culture medium were investigated for metabolic activity and colony-forming units (CFUs). Extracts taken in the cell culture medium of the specimens were used to evaluate cell viability. Results showed that the silanized nano-ZrO 2 and ABWs could improve the flexural strength of composites compared with the pure PMMA. Novaron itself had no mechanical function for composites while it had synergistic effect when it mixed with silanized nano-ZrO 2 and ABWs. And when 4 wt% (N-4) Novaron mixed in nano-ZrO 2 –ABW/PMMA composites, flexural strength achieved an increase of 44%, getting the maximum value. For the antibacterial properties, the values of MTT and CFUs of S. mutans and C. albicans biofilms on the composites surface were greatly reduced (p < 0.05) with the higher proportion of Novaron, and no significant

  7. 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 ...

  8. Effects of Ti addition on LFZ Bi-2212 thin rods

    Directory of Open Access Journals (Sweden)

    Angurel, L. A.

    2003-06-01

    Full Text Available In order to reproduce previous results in Bi-2212 single crystals, the effects associated with the addition of Ti to the precursors of Laser Floating Zone textured Bi-2212 thin rods have been analyzed. It has been found that Ti induces a great number of nucleation centers in the molten zone and, in consequence, it reduces the grain size one order of magnitude. In addition, using the same growth conditions, the texture of the sample is strongly degraded. These microstructural changes strongly affect the superconducting properties showing that Ti addition destroys the network of low angle grain boundaries that are responsible for the high critical currents in these materials.

    Se ha analizado el efecto de la introducción de Ti en precursores de Bi-2212 para ser texturados mediante láser a través del método de zona flotante, todo ello debido a los resultados esperanzadores obtenidos en monocristales. Se ha encontrado que el Ti introduce un gran número de centros de nucleación en la zona fundida, por lo que se reducen las dimensiones de los granos en un orden de magnitud aproximadamente. Por otra parte, y utilizando las mismas condiciones de crecimiento, se observa que la textura de la muestra se degrada severamente, Estos cambios microestructurales afectan en gran medida a las propiedades superconductoras, demostrándose que la introducción de Ti destruye la red de fronteras de grano de bajo ángulo, que son las responsables en estos materiales de las altas corrientes criticas.

  9. Effect of poly-α, γ, L-glutamic acid as a capping agent on morphology and oxidative stress-dependent toxicity of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Stevanović M

    2011-11-01

    Full Text Available Magdalena Stevanović1, Branimir Kovačević2, Jana Petković3, Metka Filipič3, Dragan Uskoković11Institute of Technical Sciences of Serbian Academy of Sciences and Arts, 2Institute of General and Physical Chemistry, Belgrade, Serbia; 3Department of Genetic Toxicology and Cancer Biology, National Institute of Biology, Ljubljana, SloveniaAbstract: Highly stable dispersions of nanosized silver particles were synthesized using a straightforward, cost-effective, and ecofriendly method. Nontoxic glucose was utilized as a reducing agent and poly- α, γ, L-glutamic acid (PGA, a naturally occurring anionic polymer, was used as a capping agent to protect the silver nanoparticles from agglomeration and render them biocompatible. Use of ammonia during synthesis was avoided. Our study clearly demonstrates how the concentration of the capping agent plays a major role in determining the dimensions, morphology, and stability, as well as toxicity of a silver colloidal solution. Hence, proper optimization is necessary to develop silver colloids of narrow size distribution. The samples were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurement. MTT assay results indicated good biocompatibility of the PGA-capped silver nanoparticles. Formation of intracellular reactive oxygen species was measured spectrophotometrically using 2,7-dichlorofluorescein diacetate as a fluorescent probe, and it was shown that the PGA-capped silver nanoparticles did not induce intracellular formation of reactive oxygen species.Keywords: silver nanoparticles, poly-α, γ, L-glutamic, green synthesis, morphology, cytotoxicity

  10. Mortar cohesión. The effect of additives

    Directory of Open Access Journals (Sweden)

    Castro, J. H.

    1975-12-01

    Full Text Available This study was concerned with the hydration of clinker compounds in the presence of different additives; it appeared that accelerating additives, such as calcium chloride and silicic acid, produce longer fibers of tobermorite, whereas inhibitors, such as sugar, produce shorter fibers of tobermorite. This same effect was observed in the hydration of anhydrite, in which large crystals of gypsum were produced in the presence of sodium sulphate. So the cohesion in mortars of cement and anhydrite is explained in terms of the role of fibers.Se estudia la hidratación del clínker en presencia de diferentes aditivos encontrándose que los aceleradores, como el cloruro cálcico y el ácido salicílico, producen tobermorita de fibra larga y los inhibidores, como el azúcar, tobermorita de fibra corta. Este mismo efecto se encuentra en la anhidrita, produciéndose cristales de yeso largo, en presencia del sulfato de sodio, y cristales cortos en ausencia del catalizador. La cohesión de un mortero depende luego del largo de sus fibras. Así la cohesión de los morteros de cemento y anhidrita se explican en función del rol de la fibra.

  11. Dolomite addition effects on the thermal expansion of ceramic tiles

    International Nuclear Information System (INIS)

    Marino, Luis Fernando Bruno; Boschi, Anselmo Ortega

    1997-01-01

    The thermal expansion of ceramic tiles is of greater importance in engineering applications because the ceramics are relatively brittle and cannot tolerate large internal strain imposed by thermal expansion. When ceramic bodies are produced for glazed ties the compatibility of this property of the components should be considered to avoid damage in the final products. Carbonates are an important constituent of ceramic wall-title bodies and its presence in formulations and the reactions that occur between them and other components modify body properties. The influence in expansivity by additions of calcium magnesium carbonate in a composition of wall tile bodies has been investigated. The relative content of mineralogical components was determined by X-ray diffraction and thermal expansion by dilatometric measurements. The results was indicated that with the effect of calcium-magnesium phases and porosity on thermal expansion of wall tile bodies. (author)

  12. Additional magnetoelectric effect in electrode-arrayed magnetoelectric composite

    Directory of Open Access Journals (Sweden)

    D. A. Pan

    2014-11-01

    Full Text Available An electrode-arrayed magnetoelectric (ME composite was proposed, in which the positive and negative electrodes of the PZT-5H plate (Pb(Zr0.52Ti0.48O3 were equally divided into a 2 × 5 array, while the PZT plate remained intact. The ME voltage coefficients of these 10 sections were measured individually and in parallel/series modes. The magnetoelectric coefficient is doubled compared with un-arrayed condition, when the 10 sections are connected in parallel/series using an optimized connecting sequence derived from the charge matching rule. This scheme can also be applied to other types of layered magnetoelectric composites to obtain additional magnetoelectric effect from the original composite structure.

  13. Patchy silica-coated silver nanowires as SERS substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hunyadi Murph, Simona E.; Murphy, Catherine J.

    2013-05-08

    We report a class of core-shell nanomaterials that can be used as efficient surface-enhancement Raman scattering (SERS) substrates. The core consists of silver nanowires, prepared through a chemical reduction process, that are used to capture 4- mercaptobenzoic acid (4-MBA), a model analyte. The shell was prepared through a modified Stöber method and consists of patchy or full silica coats. The formation of silica coats was monitored via transmission electron microscopy, UV-visible spectroscopy and phase-analysis light scattering for measuring effective surface charge. Surprisingly, the patchy silica coated silver nanowires are better SERS substrate than silver nanowires; nanomolar concentration of 4-MBA can be detected. In addition, “nano-matryoshka” configurations were used to quantitate/explore the effect of the electromagnetic field at the tips of the nanowire (“hot spots”) in the Raman scattering experiment.

  14. Patchy silica-coated silver nanowires as SERS substrates

    International Nuclear Information System (INIS)

    Hunyadi Murph, Simona E.; Murphy, Catherine J.

    2013-01-01

    We report a class of core–shell nanomaterials that can be used as efficient surface-enhancement Raman scattering (SERS) substrates. The core consists of silver nanowires, prepared through a chemical reduction process, that are used to capture 4-mercaptobenzoic acid (4-MBA), a model analyte. The shell was prepared through a modified Stöber method and consists of patchy or full silica coats. The formation of silica coats was monitored via transmission electron microscopy, UV–visible spectroscopy, and phase-analysis light-scattering for measuring effective surface charge. Surprisingly, the patchy silica-coated silver nanowires are better SERS substrate than silver nanowires; nanomolar concentration of 4-MBA can be detected. In addition, “nano-matryoshka” configurations were used to quantitate/explore the effect of the electromagnetic field at the tips of the nanowire (“hot spots”) in the Raman scattering experiment.

  15. Effects of γ- and x-irradiation upon activity and selectivity of a supported silver catalyst in the oxidation of ethylene and carbon monoxide

    International Nuclear Information System (INIS)

    Mora Vallejo, R.J.

    1975-01-01

    Effects of γ and x-radiation on catalytic selectivity of supported silver catalysts for production of ethylene oxide via ethylene oxidation were compared by determination of radio-induced changes in conversion-yield profiles. Influence of photon energy on the kinetics of the irradiation process was studied by determination of conversion-yield profiles, using samples of catalyst exposed to x-rays of different mean photon energy and γ-rays for different cumulative periods of time. The effect of γ-radiation on catalytic activity of the same silver catalysts for carbon monoxide oxidation was analyzed by determination of the reaction kinetics before and after catalyst irradiation

  16. The Effect of Silver Nanoparticles Size, Produced Using Plant Extract from Arbutus unedo, on Their Antibacterial Efficacy

    Directory of Open Access Journals (Sweden)

    Nicholas Skandalis

    2017-07-01

    Full Text Available Silver nanoparticles (AgNPs have been demonstrated to restrain bacterial growth, while maintaining minimal risk in development of bacterial resistance and human cell toxicity that conventional silver compounds exhibit. Several physical and chemical methods have been reported to synthesize AgNPs. However, these methods are expensive and involve heavy chemical reduction agents. An alternative approach to produce AgNPs in a cost-effective and environmentally friendly way employs a biological pathway using various plant extracts to reduce metal ions. The size control issue, and the stability of nanoparticles, remain some of the latest challenges in such methods. In this study, we used two different concentrations of fresh leaf extract of the plant Arbutus unedo (LEA as a reducing and stabilizing agent to produce two size variations of AgNPs. UV-Vis spectroscopy, Dynamic Light Scattering, Transmission Electron Microscopy, and zeta potential were applied for the characterization of AgNPs. Both AgNP variations were evaluated for their antibacterial efficacy against the gram-negative species Escherichia coli and Pseudomonas aeruginosa, as well as the gram-positive species Bacillus subtilis and Staphylococcus epidermidis. Although significant differences have been achieved in the nanoparticles’ size by varying the plant extract concentration during synthesis, the antibacterial effect was almost the same.

  17. The Effect of Silver Nanoparticles Size, Produced Using Plant Extract from Arbutus unedo, on Their Antibacterial Efficacy.

    Science.gov (United States)

    Skandalis, Nicholas; Dimopoulou, Anastasia; Georgopoulou, Anthie; Gallios, Nikolaos; Papadopoulos, Dimitrios; Tsipas, Dimitrios; Theologidis, Ioannis; Michailidis, Nikolaos; Chatzinikolaidou, Maria

    2017-07-10

    Silver nanoparticles (AgNPs) have been demonstrated to restrain bacterial growth, while maintaining minimal risk in development of bacterial resistance and human cell toxicity that conventional silver compounds exhibit. Several physical and chemical methods have been reported to synthesize AgNPs. However, these methods are expensive and involve heavy chemical reduction agents. An alternative approach to produce AgNPs in a cost-effective and environmentally friendly way employs a biological pathway using various plant extracts to reduce metal ions. The size control issue, and the stability of nanoparticles, remain some of the latest challenges in such methods. In this study, we used two different concentrations of fresh leaf extract of the plant Arbutus unedo (LEA) as a reducing and stabilizing agent to produce two size variations of AgNPs. UV-Vis spectroscopy, Dynamic Light Scattering, Transmission Electron Microscopy, and zeta potential were applied for the characterization of AgNPs. Both AgNP variations were evaluated for their antibacterial efficacy against the gram-negative species Escherichia coli and Pseudomonas aeruginosa , as well as the gram-positive species Bacillus subtilis and Staphylococcus epidermidis . Although significant differences have been achieved in the nanoparticles' size by varying the plant extract concentration during synthesis, the antibacterial effect was almost the same.

  18. Chemical changes in silver carp (Hypophthalmichthys molitrix) minced muscle during frozen storage: Effect of a previous washing process

    Energy Technology Data Exchange (ETDEWEB)

    Asgharzadeh, A.; Shabanpour, B.; Aubourg, S. P.; Hosseini, H.

    2010-07-01

    previous washing process Silver carp (Hypophthalmichthys molitrix) has acquired great attention because of its increasing farming production and application in the surimi-product commercialization. This work focuses on the effect of a washing process followed by frozen storage (6 months; -18 degree centigrade) on the quality of minced silver carp muscle. A previous washing step has led to a positive effect on fish quality according to marked content decreases in expressible moisture, volatile amines, free fatty acids and thiobarbituric acid reactive substances; such quality performances were maintained throughout the frozen storage. On the other hand, most indexes tested showed quality losses throughout the frozen storage in both washed and unwashed fish material; however, water holding capacity (WHC) remained unchanged in washed fish throughout the frozen storage. Among quality indexes, a special attention should be given to the expressible moisture value and accordingly the WHC, as being closely related to the gel forming ability in order to obtain surimi-type commercial products. (Author) 46 refs.

  19. The effect of impurity level on ultrafine-grained microstructures and their stability in low stacking fault energy silver

    International Nuclear Information System (INIS)

    Hegedus, Zoltan; Gubicza, Jeno; Kawasaki, Megumi; Chinh, Nguyen Q.; Fogarassy, Zsolt; Langdon, Terence G.

    2011-01-01

    Highlights: → Effect of impurity content on microstructure in ECAP-processed silver was studied. → There is a lower degree of twinning in the less pure material for high strains. → The samples processed for 4-16 passes showed self-annealing during storage at RT. → Small increase of impurity level resulted in a much better stability at RT. - Abstract: The effect of impurity content on the evolution of microstructure in low stacking fault energy silver processed by severe plastic deformation (SPD) was studied. The SPD-processing was carried out on 4N5 and 4N purity Ag samples by equal-channel angular pressing (ECAP) up to 16 passes. It was found that, although the minimum grain size and the maximum dislocation density were not affected by the different impurity atom content, there is a lower degree of twinning in the less pure material for high number of passes. The small increase of impurity level from 4N5 to 4N in Ag resulted in a significantly better thermal stability at room temperature for the ultrafine-grained microstructures obtained by ECAP.

  20. [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

  1. Effect of Additional Structure on Effective Stack Height of Gas Dispersion in Atmosphere

    OpenAIRE

    Takenobu Michioka; Koichi Sada; Kazuki Okabayashi

    2016-01-01

    Wind-tunnel experiments were conducted to evaluate the effect of additional structure (building, sea wall and banking) on the effective stack height, which is usually used in safety analyses of nuclear power facilities in Japan. The effective stack heights were estimated with and without the additional structure in addition to the reactor building while varying several conditions such as the source height, the height of additional structure and the distance between the source position and the...

  2. Inhibiting Effect of Additives on Pressure Solution of Calcite

    Science.gov (United States)

    Traskine, V.; Skvortsova, Z.; Badun, G.; Chernysheva, M.; Simonov, Ya.; Gazizullin, I.

    2018-05-01

    The task of protection of cultural heritage requires a better understanding of combined effects of mechanical and chemical factors involved in environmental deterioration of monuments. The present paper deals with extending some known physicochemical methods proposed for inhibiting the decay of unstressed materials to their study during water-assisted deformation. The tests have been carried out on natural limestone samples and calcite powders in CaCO3 saturated aqueous solutions under static loads causing measurable pressure solution creep. In the solutions containing 1-hydroxyethylidene-1,1-diphosphonic acid, nitrilotriacetic acid, or ethylenediaminetetraacetic acid, the creep rate decreases considerably with increasing concentration of additives. The extent of creep deceleration has been found to be proportional to the independently estimated calcite surface area occupied by adsorbed species. This fact enables us to discriminate the adsorption-induced effect from other variables controlling the pressure solution rate and may be used in screening of compounds able to minimize the environmental impact on marble and limestone objects undergoing mechanical stresses.

  3. Effect of Additives on the Physicochemical and Drug Release ...

    African Journals Online (AJOL)

    Purpose: To prepare and evaluate spherical agglomerates of pioglitazone hydrochloride (PGH) for direct compression with different additives. Method: Spherical agglomerates of pioglitazone hydrochloride were prepared by emulsion solvent diffusion method with and without additives (polyethylene glycol 6000, polyvinyl ...

  4. Study on the Effect of Heat Treatment on Physical Properties of Poplar and Beech Woods Impregnated with Nano-Copper and Nano-Silver

    Directory of Open Access Journals (Sweden)

    Hassan Siahposht

    2012-06-01

    Full Text Available Present study conducted to review effects of heat treatment on weight loss, water adsorption, and thickness swelling of poplar (Populus nigra and beech (Fagus oreintalis woods impregnated with nano-copper and nano-silver. Specimens werepressur (2.5 bar impregnated with 400 PPM water-based solution of nano-copper and nano-silver particles in a pressure vessel. For heat treatment, nano-cupper,  nano-silver impregnated and control specimens, were heat treated at 145°C temperature for 24 hours. Water absorption and thickness swelling decreased in heat treated and nano-heat treated specimens and this decrease in specimens impregnated with nano-copper and nano-silver was more obvious than in heat treated control specimens. The reasons were the degradation in crystal sections of celluloses chains and the ink variation of wood polymers. On the other hand, a comparison between heat treated and nano- heat treated specimens has shown weight loss further in nano-heat treated specimens. This shows that retent nano-copper and nano-silver by impregnation facilitates heat transfer in wood; and it may increase the process of degradation and pyrolysis of wood structures in inner parts of specimens.

  5. One-pot silver nanoring synthesis.

    OpenAIRE

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

    2009-01-01

    Abstract Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH4 in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV–vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO3/NaBH4 ratio, pH...

  6. Silver sources of archaic Greek coinage

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  7. Bioleaching of a manganese and silver Ore

    International Nuclear Information System (INIS)

    Porro, S.; Tedesco, P.H.; La Plata

    1990-01-01

    The bioleaching with a strain of Thiobacillus thiooxidans of the ore of Farallon Negro (Catamarca, Argentina) was studied in order to estimate its application to the solution and recovery of the manganese, and to improve the silver extraction. The State company which works the mine has not yet found an economical process to extract the manganese and has only reached a 30% efficiency in the recovery of silver by cianuration. The effects of pulp density variations and the addition of different quantities of FeS were analysed looking for the best working conditions. 74 μm (mesh Tyler 200) of ore particles were used because that is the size used in this plant for the cianuration process. (Author)

  8. Study of the effect of the silver content on the structural and mechanical behavior of Ag–ZrCN coatings for orthopedic prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Ferreri, I., E-mail: isabelferreri@gmail.com [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); CEB, Centre for Biological Engineering, University of Minho, Campus of Gualtar, 4700-057 (Portugal); Lopes, V. [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); Calderon V, S. [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Tavares, C.J. [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); Cavaleiro, A. [SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal); Carvalho, S. [GRF-CFUM, University of Minho, Campus of Azurém, 4800-058 Guimarães (Portugal); SEG-CEMUC, Mechanical Engineering Department, University of Coimbra, 3030-788 Coimbra (Portugal)

    2014-09-01

    With the increase of elderly population and health problems that are arising nowadays, hip joint prostheses are being widely used. However, it is estimated that 20% of hip replacement surgeries simply fails after few years, mainly due to wear fatigue. Bearing this in mind, this work reports on the development of new coatings that are able to sustain long and innocuous life inside the patient, which will confer to the usual biomaterials improved physical, mechanical and tribological properties. In particular, the development of multifunctional coatings based on Ag-ZrCN, prepared by DC reactive magnetron sputtering using two targets, Zr and a modified Zr target, in an Ar + C{sub 2}H{sub 2} + N{sub 2} atmosphere. Silver pellets were placed in the erosion area of the alloyed Zr target in order to obtain a silver content up to 8 at.%. The structural results obtained by x-ray diffraction show that the coatings crystallize in a NaCl crystal structure typical of ZrC{sub 1-x}N{sub x}. The increase of Ag content promoted the formation of an additional a-CN{sub x} amorphous phase, besides a silver crystalline phase. Hardness is decreasing, as increasing silver content. Despite the low thicknesses, adhesion values (L{sub C3}) can be considered as good. Dynamic fatigue results suggest that these coatings system can be a real asset in terms of mechanical properties, by improving the performance of usual Stainless Steel 316 L biomaterials. - Highlights: • ZrCN, silver and carbon based amorphous phases, form the structure of the coatings. • Ag–ZrCN coatings have a high capacity to withstand an impact load without fracturing. • Silver incorporation reduces the fatigue failures of the coatings. • The films possess mechanical resistance and biocompatibility, required in prostheses.

  9. The effect of silver nanoparticles (AgNPs) on proliferation and apoptosis of in ovo cultured glioblastoma multiforme (GBM) cells.

    Science.gov (United States)

    Urbańska, Kaja; Pająk, Beata; Orzechowski, Arkadiusz; Sokołowska, Justyna; Grodzik, Marta; Sawosz, Ewa; Szmidt, Maciej; Sysa, Paweł

    2015-01-01

    Recently, it has been shown that silver nanoparticles (AgNPs) provide a unique approach to the treatment of tumors, especially those of neuroepithelial origin. Thus, the aim of this study was to evaluate the impact of AgNPs on proliferation and activation of the intrinsic apoptotic pathway of glioblastoma multiforme (GBM) cells cultured in an in ovo model. Human GBM cells, line U-87, were placed on chicken embryo chorioallantoic membrane. After 8 days, the tumors were divided into three groups: control (non-treated), treated with colloidal AgNPs (40 μg/ml), and placebo (tumors supplemented with vehicle only). At the end of the experiment, all tumors were isolated. Assessment of cell proliferation and cell apoptosis was estimated by histological, immunohistochemical, and Western blot analyses. The results show that AgNPs can influence GBM growth. AgNPs inhibit proliferation of GBM cells and seem to have proapoptotic properties. Although there were statistically significant differences between control and AgNP groups in the AI and the levels of active caspase 9 and active caspase 3, the level of these proteins in GBM cells treated with AgNPs seems to be on the border between the spontaneous apoptosis and the induced. Our results indicate that the antiproliferative properties of silver nanoparticles overwhelm proapoptotic ones. Further research focused on the cytotoxic effect of AgNPs on tumor and normal cells should be conducted.

  10. Effect of Silver or Copper Nanoparticles-Dispersed Silane Coatings on Biofilm Formation in Cooling Water Systems

    Science.gov (United States)

    Ogawa, Akiko; Kanematsu, Hideyuki; Sano, Katsuhiko; Sakai, Yoshiyuki; Ishida, Kunimitsu; Beech, Iwona B.; Suzuki, Osamu; Tanaka, Toshihiro

    2016-01-01

    Biofouling often occurs in cooling water systems, resulting in the reduction of heat exchange efficiency and corrosion of the cooling pipes, which raises the running costs. Therefore, controlling biofouling is very important. To regulate biofouling, we focus on the formation of biofilm, which is the early step of biofouling. In this study, we investigated whether silver or copper nanoparticles-dispersed silane coatings inhibited biofilm formation in cooling systems. We developed a closed laboratory biofilm reactor as a model of a cooling pipe and used seawater as a model for cooling water. Silver or copper nanoparticles-dispersed silane coating (Ag coating and Cu coating) coupons were soaked in seawater, and the seawater was circulated in the laboratory biofilm reactor for several days to create biofilms. Three-dimensional images of the surface showed that sea-island-like structures were formed on silane coatings and low concentration Cu coating, whereas nothing was formed on high concentration Cu coatings and low concentration Ag coating. The sea-island-like structures were analyzed by Raman spectroscopy to estimate the components of the biofilm. We found that both the Cu coating and Ag coating were effective methods to inhibit biofilm formation in cooling pipes. PMID:28773758

  11. Effectiveness of Aloe Vera gel compared with 1% silver sulphadiazine cream as burn wound dressing in second degree burns.

    Science.gov (United States)

    Shahzad, Muhammad Naveed; Ahmed, Naheed

    2013-02-01

    To assess the efficacy of Aloe Vera gel compared with 1% silver sulfadiazine cream as a burn dressing for the treatment of superficial and partial thickness burns. This Interventional Comparative study was carried out at the Burn unit and Plastic surgery department, Nishtar Hospital Multan, Pakistan from July 2008 to December 2010. A total of 50 patients with superficial and partial thickness burns were divided into two equal groups randomly by consecutive sampling method, one group was dressed with Aloe Vera gel while the other was treated with 1% silversulphadiazine cream, and the results regarding duration of wound epithelialization, pain relief and cost of treatment were compared. In patients treated with Aloe Vera gel, healing of burn wounds were remarkably early than those patients treated with 1% silver sulfadiazine. All the patients of Aloe Vera group were relieved of pain earlier than those patients who were treated with SSD. Thermal burns patients dressed with Aloe Vera gel showed advantage compared to those dressed with SSD regarding early wound epithelialization, earlier pain relief and cost-effectiveness.

  12. Silver-loaded nanotubular structures enhanced bactericidal efficiency of antibiotics with synergistic effect in vitro and in vivo

    Directory of Open Access Journals (Sweden)

    Xu N

    2017-01-01

    Full Text Available Na Xu,1,2,* Hao Cheng,3,4,* Jiangwen Xu,1 Feng Li,3 Biao Gao,1 Zi Li,3 Chenghao Gao,3 Kaifu Huo,5 Jijiang Fu,1,2 Wei Xiong3 1The State Key Laboratory of Refractories and Metallurgy, School of Materials and Metallurgy, Wuhan University of Science and Technology, 2Institute of Biology and Medicine, Wuhan University of Science and Technology, 3Orthopaedic Department, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People’s Republic of China; 4Biomaterials Innovation Research Center, Division of Biomedical Engineering, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, USA; 5Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, People’s Republic of China *These authors contributed equally to this work Abstract: Antibiotic-resistant bacteria have become a major issue due to the long-term use and abuse of antibiotics in treatments in clinics. The combination therapy of antibiotics and silver (Ag nanoparticles is an effective way of both enhancing the antibacterial effect and decreasing the usage of antibiotics. Although the method has been proved to be effective in vitro, no in vivo tests have been carried out at present. Herein, we described a combination therapy of local delivery of Ag and systemic antibiotics treatment in vitro in an infection model of rat. Ag nanoparticle-loaded TiO2 nanotube (NT arrays (Ag-NTs were fabricated on titanium implants for a customized release of Ag ion. The antibacterial properties of silver combined with antibiotics vancomycin, rifampin, gentamicin, and levofloxacin, respectively, were tested in vitro by minimum inhibitory concentration (MIC assay, disk diffusion assay, and antibiofilm formation test. Enhanced antibacterial activity of combination therapy was observed for all the chosen bacterial strains, including gram-negative Escherichia coli (ATCC 25922, gram

  13. Effect of Silver Nitrate DuringEx vitro Acclimatization of Micropropagated Ginger Cultivars

    Directory of Open Access Journals (Sweden)

    Dikash Singh THINGBAIJAM

    2014-03-01

    Full Text Available Silver nitrate (AgNO3 was used under in vitro conditions to study the response of ginger cultivars ‘Nadia’ and ‘Baishey’ under ex vitro. Micropropagated plants treated with AgNO3 showed significant difference (p<0.05 compared to those plantlets without AgNO3 and control type in almost all the different quantitative traits analyzed. Significant difference in number of finger per plant and minirhizome yield indicated the repercussion of AgNO3 during acclimatization.

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

    Science.gov (United States)

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

    2006-03-01

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

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  16. Synthesis of Functionalized Fluorescent Silver Nanoparticles and their toxicological effect in aquatic environments (Goldfish) and HEPG2 cells.

    Science.gov (United States)

    Santos, Hugo; Oliveira, Elisabete; Garcia-Pardo, Javier; Diniz, Mário; Lorenzo, Julia; Rodriguez-González, Benito; Capelo, José Luis; Lodeiro, Carlos

    2013-12-01

    Silver nanoparticles, AgNPs, are widely used in our daily life, mostly due to their antibacterial, antiviral and antifungal properties. However, their potential toxicity remains unclear. In order to unravel this issue, emissive AgNPs were first synthetized using an inexpensive photochemical method, and then their permeation was assessed in vivo in goldfish and in vitro in human hepatoma cells (HepG2). In addition, the oxidative stress caused by AgNPs was assessed in enzymes such as glutathione-S-transferase (GST), catalase (CAT) and in lipid peroxidation (LPO). This study demonstrates that the smallest sized AgNPs@3 promote the largest changes in gold fish livers, whereas AgNPs@1 were found to be toxic in HEPG2 cells depending on both the size and functionalized/stabilizer ligand.

  17. Synthesis of Functionalized Fluorescent Silver Nanoparticles and their toxicological effect in aquatic environments (Goldfish and HEPG2 cells.

    Directory of Open Access Journals (Sweden)

    Hugo Miguel Santos

    2013-12-01

    Full Text Available Silver nanoparticles, AgNPs, are widely used in our daily life, mostly due to their antibacterial, antiviral and antifungal properties. However, their potential toxicity remains unclear. In order to unravel this issue, emissive AgNPs were first synthetized using an inexpensive photochemical method, and then their permeation was assessed in vivo in goldfish and in vitro in human hepatoma cells (HepG2. In addition, the oxidative stress caused by AgNPs was assessed in enzymes such as glutathione-S-transferase (GST, catalase (CAT and in lipid peroxidation (LPO. This study demonstrates that the smallest sized AgNPs@3 promote the largest changes in gold fish livers, whereas AgNPs@1 were found to be toxic in HEPG2 cells depending on both the size and functionalized/stabilizer ligand.

  18. Radiation Effects on Thermoluminescence Characteristics of HDPE Containing Additives

    International Nuclear Information System (INIS)

    Kim, Ki Yup; Lee, Chung; Ryu, Boo Hyung

    2005-01-01

    Polymeric materials are widely used for electrical insulation in a broad range of applications that cover the power supply industry to inner and outer space. However, the electrical performance of these materials could be compromised by their working environment and one of the most deleterious is that where a nuclear radiation is present. Radiation effects on polymers can be interpreted by two main reactions, a cross-linking reaction and degradation reactions or a main-chain scission process. There are no absolute rules for determining whether or not any given polymer will cross-link or degrade upon an irradiation. But, the polymers can be divided empirically into two groups; polymers which are crosslinked by radiation (especially by the incorporation of chemical cross-linking promoters) and polymers which degrade by radiation into a product of lower molecular weight due to random main-chain scission process. These polymers become very hard and brittle with a high dose of radiation. Most polymeric materials contain some stabilizers such as flame retardant and antioxidant to prevent combustion and oxidation. Because of these additives, degradation mechanism of the polymer became complicated. Many of the novel properties of the insulating materials used in nuclear power plants are important for radiation degradation. Therefore we have used the thermal methods such as thermoluminescence (TL) detection for irradiated high density polyethylene containing flame retardant and antioxidant

  19. Understanding the Effects of NaCl, NaBr and Their Mixtures on Silver Nanowire Nucleation and Growth in Terms of the Distribution of Electron Traps in Silver Halide Crystals

    Directory of Open Access Journals (Sweden)

    Yunjun Rui

    2018-03-01

    Full Text Available In recent years, many research groups have synthesized ultra-thin silver nanowires (AgNWs with diameters below 30 nm by employing Cl− and Br− simultaneously in the polyol process. However, the yield of AgNWs in this method was low, due to the production of Ag nanoparticles (AgNPs as an unwanted byproduct, especially in the case of high Br− concentration. Here, we investigated the roles of Cl− and Br− in the preparation of AgNWs and then synthesized high aspect ratio (up to 2100 AgNWs in high yield (>85% AgNWs using a Cl− and Br− co-mediated method. We found that multiply-twinned particles (MTPs with different critical sizes were formed and grew into AgNWs, accompanied by a small and large amount of AgNPs for the NaCl and NaBr additives, respectively. For the first time, we propose that the growth of AgNWs of different diameters and yields can be understood based on the electron trap distribution (ETD of the silver halide crystals. For the case of Cl− and Br− co-additives, a mixed silver halide crystal of AgBr1−xClx was formed, rather than the AgBr/AgCl mixture reported previously. In this type of crystal, the ETD is uniform, which is beneficial for the synthesis of AgNWs with small diameter (30~40 nm and high aspect ratio. AgNW transparent electrodes were prepared in air by rod coating. A sheet resistance of 48 Ω/sq and transmittance of 95% at 550 nm were obtained without any post-treatment.

  20. 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.

  1. A comparative study of the effect of α-, β-, and γ-cyclodextrins as stabilizing agents in the synthesis of silver nanoparticles using a green chemistry method

    Energy Technology Data Exchange (ETDEWEB)

    Suárez-Cerda, Javier [Centro de Graduados e Investigación, Instituto Tecnológico de Tijuana, Apartado Postal 1166, Tijuana, B. C. (Mexico); Nuñez, Gabriel Alonso [Centro de Nanociencia y Nanotecnología de la UNAM, CNyN, Km. 107 Carretera Tijuana-Ensenada, C.P. 22860 Ensenada, B. C. (Mexico); Espinoza-Gómez, Heriberto [Facultad de Ciencias Químicas e Ingeniería, UABC, Calzada Universidad 14418 Parque Industrial Internacional, C.P. 22390 Tijuana, B.C. (Mexico); Flores-López, Lucía Z., E-mail: lzflores@hotmail.com [Centro de Graduados e Investigación, Instituto Tecnológico de Tijuana, Apartado Postal 1166, Tijuana, B. C. (Mexico)

    2014-10-01

    This paper describes the effect of different types of cyclodextrins (CDs) in the synthesis of silver nanoparticles (Ag-NPs), using an easy green chemistry method. The Ag-NPs were obtained using an aqueous silver nitrate solution (AgNO{sub 3}) with α-, β-, or γ-CDs (aqueous solutions) as stabilizing agents, employing the chemical reduction method with citric acid as a reducing agent. A comparative study was done to determine which cyclodextrin (CD) was the best stabilizing agent, and we found out that β-CD was the best due to the number of glucopyranose units in its structure. The formation of the Ag-NPs was demonstrated by analysis of UV–vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) and transmission electron microscopy (TEM). SEM–EDS showed the formation of a cluster with a significant amount of silver, for β-CD-Ag-NPs, spherical agglomerates can be observed. However, for α-, γ-CD, the agglomerates do not have a specific form, but their appearance is porous. TEM analysis shows spherical nanoparticles in shape and size between ∼ 0.5 to 7 nm. The clear lattice fringes in TEM images and the typical selected area electron diffraction (SAED) pattern, showed that the Ag-NPs obtained were highly crystalline with a face cubic center structure (FCC). - Highlights: • We report a green chemistry method for silver nanoparticles (Ag-NPs) synthesis. • We study the effect of cyclodextrin type on the silver nanoparticles (Ag-NPs) synthesis. • The silver nanoparticles (Ag-NPs) characterization were done by UV–vis, AFM, SEM–EDS, and TEM. • The Ag-NPs obtained have a face cubic center structure (FCC). • The nanoparticles obtained are spherical in shape and between ∼ 0.5 and 7 nm in size.

  2. A comparative study of the effect of α-, β-, and γ-cyclodextrins as stabilizing agents in the synthesis of silver nanoparticles using a green chemistry method

    International Nuclear Information System (INIS)

    Suárez-Cerda, Javier; Nuñez, Gabriel Alonso; Espinoza-Gómez, Heriberto; Flores-López, Lucía Z.

    2014-01-01

    This paper describes the effect of different types of cyclodextrins (CDs) in the synthesis of silver nanoparticles (Ag-NPs), using an easy green chemistry method. The Ag-NPs were obtained using an aqueous silver nitrate solution (AgNO 3 ) with α-, β-, or γ-CDs (aqueous solutions) as stabilizing agents, employing the chemical reduction method with citric acid as a reducing agent. A comparative study was done to determine which cyclodextrin (CD) was the best stabilizing agent, and we found out that β-CD was the best due to the number of glucopyranose units in its structure. The formation of the Ag-NPs was demonstrated by analysis of UV–vis spectroscopy, atomic force microscopy (AFM), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) and transmission electron microscopy (TEM). SEM–EDS showed the formation of a cluster with a significant amount of silver, for β-CD-Ag-NPs, spherical agglomerates can be observed. However, for α-, γ-CD, the agglomerates do not have a specific form, but their appearance is porous. TEM analysis shows spherical nanoparticles in shape and size between ∼ 0.5 to 7 nm. The clear lattice fringes in TEM images and the typical selected area electron diffraction (SAED) pattern, showed that the Ag-NPs obtained were highly crystalline with a face cubic center structure (FCC). - Highlights: • We report a green chemistry method for silver nanoparticles (Ag-NPs) synthesis. • We study the effect of cyclodextrin type on the silver nanoparticles (Ag-NPs) synthesis. • The silver nanoparticles (Ag-NPs) characterization were done by UV–vis, AFM, SEM–EDS, and TEM. • The Ag-NPs obtained have a face cubic center structure (FCC). • The nanoparticles obtained are spherical in shape and between ∼ 0.5 and 7 nm in size

  3. An efficient way to prepare silver nanorods in high concentration by polyol method without adding other metal or salt

    International Nuclear Information System (INIS)

    Chen Yong; Guan Jianguo; Xie Hongquan

    2012-01-01

    Using ethylene glycol as solvent and reductant, polyvinyl pyrrolidone(PVP) as capping agent under the action of appropriately preformed silver crystal seeds and controlled addition rates of silver nitrate and PVP solution, silver nanorods with length of 2–15 μm and diameter of 200–880 nm can be obtained in high concentration of AgNO 3 as 0.50 M. In the absence of the preformed seeds, nanorods cannot be obtained as the main product, if the AgNO 3 concentration is over 0.10 M. It is necessary to use the appropriately preformed silver crystal seeds for the high concentration preparation of silver nanorods. Transmission Electron Microscopy images showed that Ag seeds preformed at appropriate silver nitrate concentrations exhibited the multiply twinned particles of decahedral shape(MTPs), which formed Ag nanorods in the presence of PVP. Through study of the effects of various factors on the nanostructure of silver, the favorable conditions are: appropriately preformed seeds concentration at 6.54–9.81 mM, addition rate of AgNO 3 solution at 0.30–0.43 mL min −1 and molar ratio of PVP/AgNO 3 at 1.1–1.4, in order to control the crystal growth rate of silver matching the reduction rate of AgNO 3 by ethylene glycol. The nanorods obtained were characterized by Scanning Electron Microscopy, EDX, XRD, Raman spectrometry, Infrared Spectrophotometry and Ultraviolet Spectrophotometry. On the base of the above results, the mechanism of rates matching for obtaining silver nanorods was briefly discussed. This method is a simple, facile and economical method using high concentration with high yield without using other metal or salt to massively synthesize silver nanorods through adding preformed silver seeds to control the reduction rate of silver nitrate and the crystal growth rate of silver nanorods. As compared to the conventional polyol method using lower silver nitrate concentration, this method can save ethylene glycol used and time of operation and the as

  4. Antimicrobial Effectiveness of Cellulose based Fabrics treated with Silver Nitrate Solution using Plasma Processes

    Directory of Open Access Journals (Sweden)

    Jelena Peran

    2017-12-01

    Full Text Available In order to obtain antibacterial properties, the possibility of deposition of silver particles from silver nitrate (AgNO3 solutions by plasma deposition process using argon as a carrier gas (PDP-Ar was explored. Hexamethyldisiloxane and acrylic acid were used as precursors and were deposited by plasma enhanced-chemical vapor deposition (PE-CVD. The processes were carried out on lyocell and modal fbrics and antimicrobial efficacy was determined on E. coli and S. aureus using time kill assay method. The results of minimal inhibitory concentration (MIC show that higher antimicrobial efficacy on E. coli is exhibited by the solution of (AgNO3 in ethylene-glycol (0.066 μg/ml rather than in absolute ethanol (0.265 μg/ml. For S. aureus, minimal inhibitory concentrations of AgNO3 solutions in both absolute ethanol and ethylene-glycol as solvents are obtained at the same value (0.132 μg/ml. Overall, the best antibacterial eff ect for both modal and lyocell samples has been achieved against E. coli using treatments with precursors (AAC and HMDSO and Ag-NO3