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Sample records for ag np thin

  1. Synthesis, characterisation and antibacterial activity of PVA/TEOS/Ag-Np hybrid thin films.

    PubMed

    Bryaskova, Rayna; Pencheva, Daniela; Kale, Girish M; Lad, Umesh; Kantardjiev, T

    2010-09-01

    Novel hybrid material thin films based on polyvinyl alcohol (PVA)/tetraethyl orthosilicate (TEOS) with embedded silver nanoparticles (AgNps) were synthesized using sol-gel method. Two different strategies for the synthesis of silver nanoparticles in PVA/TEOS matrix were applied based on reduction of the silver ions by thermal annealing of the films or by preliminary preparation of silver nanoparticles using PVA as a reducing agent. The successful incorporation of silver nanoparticles ranging from 5 to 7nm in PVA/TEOS matrix was confirmed by TEM and EDX analysis, UV-Vis spectroscopy and XRD analysis. The antibacterial activity of the synthesized hybrid materials against etalon strains of three different groups of bacteria -Staphylococcus aureus (gram-positive bacteria), Escherichia coli (gram-negative bacteria), Pseudomonas aeruginosa (non-ferment gram-negative bacteria) has been studied as they are commonly found in hospital environment. The hybrid materials showed a strong bactericidal effect against E. coli, S. aureus and P. aeruginosa and therefore have potential applications in biotechnology and biomedical science.

  2. Surface-enhanced Raman scattering from AgNP-graphene-AgNP sandwiched nanostructures

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Xu, Yijun; Xu, Pengyu; Pan, Zhenghui; Chen, Sheng; Shen, Qishen; Zhan, Li; Zhang, Yuegang; Ni, Weihai

    2015-10-01

    We developed a facile approach toward hybrid AgNP-graphene-AgNP sandwiched structures using self-organized monolayered AgNPs from wet chemical synthesis for the optimized enhancement of the Raman response of monolayer graphene. We demonstrate that the Raman scattering of graphene can be enhanced 530 fold in the hybrid structure. The Raman enhancement is sensitively dependent on the hybrid structure, incident angle, and excitation wavelength. A systematic simulation is performed, which well explains the enhancement mechanism. Our study indicates that the enhancement resulted from the plasmonic coupling between the AgNPs on the opposite sides of graphene. Our approach towards ideal substrates offers great potential to produce a ``hot surface'' for enhancing the Raman response of two-dimensional materials.We developed a facile approach toward hybrid AgNP-graphene-AgNP sandwiched structures using self-organized monolayered AgNPs from wet chemical synthesis for the optimized enhancement of the Raman response of monolayer graphene. We demonstrate that the Raman scattering of graphene can be enhanced 530 fold in the hybrid structure. The Raman enhancement is sensitively dependent on the hybrid structure, incident angle, and excitation wavelength. A systematic simulation is performed, which well explains the enhancement mechanism. Our study indicates that the enhancement resulted from the plasmonic coupling between the AgNPs on the opposite sides of graphene. Our approach towards ideal substrates offers great potential to produce a ``hot surface'' for enhancing the Raman response of two-dimensional materials. Electronic supplementary information (ESI) available: Additional SEM images, electric field enhancement profiles, Raman scattering spectra, and structure-dependent peak ratios. See DOI: 10.1039/c5nr04500b

  3. Chitosan nanocomposite films based on Ag-NP and Au-NP biosynthesis by Bacillus Subtilis as packaging materials.

    PubMed

    Youssef, Ahmed M; Abdel-Aziz, Mohamed S; El-Sayed, Samah M

    2014-08-01

    Chitosan-silver (CS-Ag) and Chitosan-gold (CS-Au) nanocomposites films were synthesized by a simple chemical method. A local bacterial isolate identified as Bacillus subtilis ss subtilis was found to be capable to synthesize both silver nanoparticles (Ag-NP) and gold nanoparticles (Au-NP) from silver nitrate (AgNO3) and chloroauric acid (AuCl(4-)) solutions, respectively. The biosynthesis of both Ag-NP and Au-NP characterize using UV/vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD), and then added to chitosan by different ratios (0.5, 1 and 2%). The prepared chitosan nanocomposites films were characterize using UV, XRD, SEM and TEM. Moreover, the antibacterial activity of the prepared films was evaluated against gram positive (Staphylococcus aureus) and gram negative bacteria (Pseudomonas aerugenosa), fungi (Aspergillus niger) and yeast (Candida albicans). Therefore, these materials can be potential used as antimicrobial agents in packaging applications.

  4. AgNP-DNA@GQDs hybrid: new approach for sensitive detection of H2O2 and glucose via simultaneous AgNP etching and DNA cleavage.

    PubMed

    Wang, Lili; Zheng, Jing; Li, Yinhui; Yang, Sheng; Liu, Changhui; Xiao, Yue; Li, Jishan; Cao, Zhong; Yang, Ronghua

    2014-12-16

    A growing body of evidence suggests that hydrogen peroxide (H2O2) plays an active role in the regulation of various physiological processes. Development of sensitive probes for H2O2 is an urgent work. In this study, we proposed a DNA-mediated silver nanoparticle and graphene quantum dot hybrid nanocomposite (AgNP-DNA@GQDs) for sensitive fluorescent detection of H2O2. The sensing mechanism is based on the etching effect of H2O2 to AgNPs and the cleavage of DNA by as-generated hydroxyl radicals (•OH). The formation of AgNP-DNA@GQDs nanocomposite can result in fluorescence quenching of GQDs by AgNPs through the resonance energy transfer. Upon H2O2 addition, the energy transfer between AgNPs and GQDs mediated by DNA was weakened and obvious fluorescence recovery of GQDs could be observed. It is worth noting that the reaction product •OH between H2O2 and AgNPs could cleave the DNA-bridge and result in the disassembly of AgNP-DNA@GQDs to achieve further signal enhancement. With optimal conditions, the approach achieves a low detection limit of 0.10 μM for H2O2. Moreover, this nanocomposite is further extended to the glucose sensing in human urine combining with glucose oxidase (GOx) for the oxidation of glucose and formation of H2O2. The glucose concentrations in human urine are detected with satisfactory recoveries of 94.6-98.8% which holds potential for ultrasensitive quantitative analysis of glucose and supplies valuable information for diabetes mellitus research and clinical diagnosis. PMID:25390796

  5. Composite PLGA/AgNpPGA/AscH nanospheres with combined osteoinductive, antioxidative, and antimicrobial activities.

    PubMed

    Stevanović, Magdalena; Uskoković, Vuk; Filipović, Miloš; Škapin, Srečo D; Uskoković, Dragan

    2013-09-25

    The global rise in the resistance of pathogens to conventional antibiotics has created an intensive search for alternative materials with antimicrobial properties. This study is performed with an intention to investigate the combined effects of poly(l-glutamic acid)-capped silver nanoparticles (AgNpPGA) and ascorbic acid (AscH) encapsulated within freeze-dried poly(lactide-co-glycolide) (PLGA) nanospheres to obtain a nanomaterial with simultaneous osteoinductive, antioxidative, and prolonged antimicrobial properties. The influence of PLGA/AgNpPGA/AscH particles on (i) viability and superoxide production of human umbilical vein endothelial cells in vitro, (ii) morphology and expression of osteogenic markers in osteoblastic MC3T3-E1 cells in vitro, and (iii) antimicrobial activity against a Gram-positive bacterium, methicillin-resistant Staphylococcus aureus, and a Gram-negative bacterium, Escherichia coli, was investigated. PLGA/AgNpPGA/AscH nanoparticles showed a superior and extended antibacterial activity against both types of bacteria. The nanoparticles appeared to be capable of delivering ascorbate to the cells, which was evidenced by the significant decrease in the level of superoxides in human umbilical vein endothelial cells and which could have a therapeutic potential in preventing oxidative stress. PLGA/AgNpPGA/AscH nanoparticles had a positive effect on MC3T3-E1 osteoblastic cells in vitro, promoting: (i) an intimate contact with the cells and preservation of their healthy morphologies; (ii) unreduced cell viability; and (iii) multiple-fold upregulation of two osteogenic markers: osteocalcin and type I procollagen. It is concluded that PLGA/AgNpPGA/AscH nanospheres present a promising new material for the treatment of infections and use in wound dressings and other prophylactic applications.

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

    PubMed

    Luo, Jiwen; Xie, Meijia; Wang, Xiaoying

    2014-02-01

    Silver nanoparticles (Ag NPs) were synthesized rapidly in one pot via the Tollens reaction, in which quaternized chitosan (QCS) and rectorite (REC) acted as the reducing and stabilizing agent, while other chemical reducing and stabilizing agents and the surfactant were not included. X-ray diffraction, scanning electron microscopy and transmission electron microscopy results showed that spherical Ag NPs with uniform sizes were obtained, the layers of clay were peeled and thus exfoliated QCS/REC/Ag NP (QCRAg) nanocomposite was achieved. Moreover, Ag NPs dispersed well in the exfoliated nanocomposite matrix, some Ag NPs even entered into the interlayer of REC. QCRAg nanocomposites showed strong antimicrobial activity; the lowest minimum inhibitory concentration against Staphyloccocus aureus was only 0.0001% (w/v). The study reveals that the obtained QCRAg nanocomposites have great potential for biomedical applications. PMID:24457172

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

    PubMed

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

    2014-12-01

    Preparation of protective coating possessing antimicrobial properties is present day need as they increase the shelf life of fruits and vegetables. In the present study, preparation of agar-silver nanoparticle film for increasing the shelf life of fruits is reported. Silver nanoparticles (Ag-NPs) biosynthesised using an extract of Ocimum sanctum leaves, were mixed with agar-agar to prepare an agar-silver nanoparticles (A-AgNp) film. This film was surface-coated over the fruits, Citrus aurantifolium (Thornless lime) and Pyrus malus (Apple), and evaluated for the determination of antimicrobial activity of A-AgNp films using disc diffusion method, weight loss and shelf life of fruits. This study demonstrates that these A-AgNp films possess antimicrobial activity and also increase the shelf life of fruits. PMID:25429496

  8. Electronic properties and bonding characteristics of AlN:Ag thin film nanocomposites

    SciTech Connect

    Lekka, Ch. E.; Patsalas, P.; Komninou, Ph.; Evangelakis, G. A.

    2011-03-01

    We present theoretical and experimental results on the bonding and structural characteristics of AlN:Ag thin film nanocomposites obtained by means of density functional theory (DFT) computations, high resolution transmission electron microscopy (HRTEM) observations, Auger electron spectroscopy (AES), and x-ray diffraction (XRD) measurements. From the theoretical calculations it was determined that the presence of the Ag substitutional of N or Al atoms affects the electronic density of states (EDOS) of the resulting systems. In particular, occupied energy states are introduced (between others) that lie within the energy gap of the AlN matrix due to Ag-d, Al-p (accompanied with a charge transfer from Al to Ag), Ag-p, and N-p hybridizations, respectively. The effect is predicted to be even more pronounced in the case of Ag nanoparticle inclusions affecting the EDOS of the composite system. These predictions were verified by the HRTEM images that gave unequivocal evidence for the presence and stability of Ag nanoparticles in the AlN matrix. In addition, the AES data suggested a metal-metal (Ag-Al) bonding preference, while the XRD patterns revealed that the atomic Ag dispersions in the AlN thin films results in a small elongation of the Wurtzite lattice, which is in agreement with the DFT predictions. These results may useful in tailoring the electronic response of AlN-based systems and the design of devices for various opto-electronic applications.

  9. Ag-NP@Ge-nanotaper/Si-micropillar ordered arrays as ultrasensitive and uniform surface enhanced Raman scattering substrates

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Meng, Guowen; Li, Zhongbo; Huang, Zhulin; Li, Xiangdong

    2015-10-01

    Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform morphology, the hierarchical Ag-NP@Ge-nanotaper/Si-micropillar arrays exhibit strong and reproducible SERS activity. Using our hierarchical 3D SERS-substrates, both methyl parathion (a commonly used pesticide) and PCB-2 (one congener of highly toxic polychlorinated biphenyls) with concentrations down to 10-7 M and 10-5 M have been detected respectively, showing great potential in SERS-based rapid trace-level detection of toxic organic pollutants in the environment.Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform

  10. Pressureless Bonding Using Sputtered Ag Thin Films

    NASA Astrophysics Data System (ADS)

    Oh, Chulmin; Nagao, Shijo; Suganuma, Katsuaki

    2014-12-01

    To improve the performance and reliability of power electronic devices, particularly those built around next-generation wide-bandgap semiconductors such as SiC and GaN, the bonding method used for packaging must change from soldering to solderless technology. Because traditional solders are problematic in the harsh operating conditions expected for emerging high-temperature power devices, we propose a new bonding method in this paper, namely a pressureless, low-temperature bonding process in air, using abnormal grain growth on sputtered Ag thin films to realize extremely high temperature resistance. To investigate the mechanisms of this bonding process, we characterized the microstructural changes in the Ag films over various bonding temperatures and times. We measured the bonding properties of the specimens by a die-shear strength test, as well as by x-ray diffraction measurements of the residual stress in the Ag films to show how the microstructural developments were essential to the bonding technology. Sound bonds with high die strength can be achieved only with abnormal grain growth at optimum bonding temperature and time. Pressureless bonding allows for production of reliable high-temperature power devices for a wide variety of industrial, energy, and environmental applications.

  11. Enhanced resistive switching effect in Ag nanoparticle embedded BaTiO{sub 3} thin films

    SciTech Connect

    Au, K.; Wang, Juan; Bao, Z. Y.; Dai, J. Y.; Gao, X. S.; Liu, J. M.

    2013-07-14

    Ag nanoparticle (NP) embedded BaTiO{sub 3} (BTO) thin films on SrRuO{sub 3}-coated SrTiO{sub 3} (STO) substrates are prepared by the integrated nanocluster beam deposition and laser-molecular beam epitaxy. Enhanced resistive switching, up to an ON/OFF ration of 10{sup 4}, has been achieved at low switching voltage (less than 1 V) without a forming voltage. These characteristics make such nanocomposite film very promising for application of low voltage non-volatile random access memory. The enhanced resistive switching effect may be attributed to the charge storage effect of the Ag nanoparticles and easy formation of Ag filament inside the BTO film.

  12. Speciation and lability of Ag-, AgCl-, and Ag2S-nanoparticles in soil determined by X-ray absorption spectroscopy and diffusive gradients in thin films.

    PubMed

    Sekine, R; Brunetti, G; Donner, E; Khaksar, M; Vasilev, K; Jämting, Å K; Scheckel, K G; Kappen, P; Zhang, H; Lombi, E

    2015-01-20

    Long-term speciation and lability of silver (Ag-), silver chloride (AgCl-), and silver sulfide nanoparticles (Ag2S-NPs) in soil were studied by X-ray absorption spectroscopy (XAS), and newly developed “nano” Diffusive Gradients in Thin Films (DGT) devices. These nano-DGT devices were designed specifically to avoid confounding effects when measuring element lability in the presence of nanoparticles. The aging profile and stabilities of the three nanoparticles and AgNO3 (ionic Ag) in soil were examined at three different soil pH values over a period of up to 7 months. Transformation of ionic Ag, Ag-NP and AgCl-NPs were dependent on pH. AgCl formation and persistence was observed under acidic conditions, whereas sulfur-bound forms of Ag dominated in neutral to alkaline soils. Ag2S-NPs were found to be very stable under all conditions tested and remained sulfur bound after 7 months of incubation. Ag lability was characteristically low in soils containing Ag2S-NPs. Other forms of Ag were linked to higher DGT-determined lability, and this varied as a function of aging and related speciation changes as determined by XAS. These results clearly indicate that Ag2S-NPs, which are the most environmentally relevant form of Ag that enter soils, are chemically stable and have profoundly low Ag lability over extended periods. This may minimize the long-term risks of Ag toxicity in the soil environment. PMID:25436975

  13. A direct assay of carboxyl-containing small molecules by SALDI-MS on a AgNP/rGO-based nanoporous hybrid film.

    PubMed

    Hong, Min; Xu, Lidan; Wang, Fangli; Geng, Zhirong; Li, Haibo; Wang, Huaisheng; Li, Chen-Zhong

    2016-04-25

    Silver nanoparticles (AgNPs) and reduced graphene oxide (rGO) hybrid nanoporous structures fabricated by the layer-by-layer (LBL) electrostatic self-assembly have been applied as a simple platform for the rapid analysis of carboxyl-containing small molecules by surface-assisted laser desorption/ionization (D/I) mass spectrometry (SALDI-MS). By the simple one-step deposition of analytes onto the (AgNP/rGO)9 multilayer film, the MS measurements of various carboxyl-containing small molecules (including amino acids, fatty acids and organic dicarboxylic acids) can be done. In contrast to other energy transfer materials relative to AgNPs, the signal interferences of a Ag cluster (Agn(+) or Agn(-)) and a C cluster (Cn(+) or Cn(-)) have been effectively reduced or eliminated. The effects of various factors, such as the pore structure and composition of the substrates, on the efficiency of D/I have been investigated by comparing with the (AgNP)9 LBL nanoporous structure, (AgNP/rGO)9/(SiO2NP)6 LBL multilayer film and AgNP/prGO nanocomposites.

  14. Effect of temperature on oxidative stress parameters and enzyme activity in tissues of Cape River crab (Potamanautes perlatus) following exposure to silver nanoparticles (AgNP).

    PubMed

    Walters, Chavon R; Cheng, Paul; Pool, Edmund; Somerset, Vernon

    2016-01-01

    Biomarkers of oxidative stress have been widely used in environmental assessments to evaluate the effects of exposure of aquatic organisms to contaminants from various anthropogenic sources. Silver nanoparticles (AgNP), the most produced NP worldwide and used in several consumer products, are known to produce oxidative stress in aquatic organisms. Similarly, temperature is also known to affect reactive oxygen species (ROS) by influencing the inputs of contaminants into the environment, as well as altering behavior, fate, and transport. Aquatic ecosystems are affected by both anthropogenic releases of contaminants and increased temperature. To test this hypothesis, the influence of AgNP and temperature in the response to multiple biomarkers of oxidative stress was studied in the gills and hepatopancreas of the Cape River crab Potamonautes perlatus. Responses were assessed through activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and the nonenzymatic antioxidant glutathione S-transferase (GST). The response of the oxidative stress biomarkers analyzed was always higher in hepatopancreas than in gills. Elevated temperatures (28°C) induced oxidative stress by increasing SOD, CAT, and GST activities, particularly at 100 µg/ml AgNP. These data indicate that AgNP-mediated toxicity to P. perlatus is modulated by elevated temperatures, but this relationship is not linear. Co-effects of AgNP and temperature are reported for the first time in P. perlatus. PMID:26730549

  15. Determination of weight distribution ratios of Pa(V) and Np(V) with some extraction chromatography resins and the AG1-X8 resin.

    PubMed

    Mendes, M; Aupiais, J; Jutier, C; Pointurier, F

    2013-05-30

    Literature data on distribution ratios (Dw) of Np(V) and Pa(V) for the AG1-X8 resin are scarce whereas those related on resin capacity factors (k') values for TEVA, TRU and U/TEVA resins are absent. Therefore, batch extraction experiments for Pa(V) and Np(V) from HCl and HNO3 media were realized, at tracer scale, with AG1-X8 and EIChroM resins (TEVA, TRU and U/TEVA). Based on the new Dw and k' values obtained in this study, a new protocol for Pa/Np separation has been developed leading to a better separation factor of 10(5) and a chemical yield of 97±3% and 99±1% for Pa and Np, respectively. A separation of (231)Pa from uranium matrix was successfully tested.

  16. Determination of weight distribution ratios of Pa(V) and Np(V) with some extraction chromatography resins and the AG1-X8 resin.

    PubMed

    Mendes, M; Aupiais, J; Jutier, C; Pointurier, F

    2013-05-30

    Literature data on distribution ratios (Dw) of Np(V) and Pa(V) for the AG1-X8 resin are scarce whereas those related on resin capacity factors (k') values for TEVA, TRU and U/TEVA resins are absent. Therefore, batch extraction experiments for Pa(V) and Np(V) from HCl and HNO3 media were realized, at tracer scale, with AG1-X8 and EIChroM resins (TEVA, TRU and U/TEVA). Based on the new Dw and k' values obtained in this study, a new protocol for Pa/Np separation has been developed leading to a better separation factor of 10(5) and a chemical yield of 97±3% and 99±1% for Pa and Np, respectively. A separation of (231)Pa from uranium matrix was successfully tested. PMID:23680558

  17. Preparation, characterization, and bacteriostasis of AgNP-coated β-CD grafting cellulose beads.

    PubMed

    Wang, Ting; Li, Bin; Lin, Li

    2013-03-01

    A novel functional material of β-cyclodextrin (β-CD) grafting cellulose beads containing immobilized silver nanoparticles (AgNPs) is presented in this paper. The morphology was characterized by scanning electron microscopy, energy-dispersive X-ray, and X-ray photoelectron spectroscopy. Phenolphthalein probe molecule technique was used to detect the activity of the grafting β-CD, and the results demonstrated that the deposition of AgNPs had no influence on its encapsulation ability. Acid resistance of the AgNPs on the bead material was studied by atomic absorption spectrometry. The stability of the AgNPs was enhanced due to the grafting of β-CD. Tube dilution method was applied to study the bacteriostatic effect, and the minimal inhibitory doses of the novel material against Escherichia coli and Staphylococcus aureus were 12.5 and 25 mg, respectively. The minimal bactericidal doses for the two bacteria were 25 and 25 mg, respectively. PMID:23340866

  18. Silver nanoparticles coated with natural polysaccharides as models to study AgNP aggregation kinetics using UV-Visible spectrophotometry upon discharge in complex environments.

    PubMed

    Lodeiro, Pablo; Achterberg, Eric P; Pampín, Joaquín; Affatati, Alice; El-Shahawi, Mohammed S

    2016-01-01

    This study provides quantitative information on the aggregation and dissolution behaviour of silver nanoparticles (AgNPs) upon discharge in fresh and sea waters, represented here as NaCl solutions of increasing ionic strength (up to 1M) and natural fjord waters. Natural polysaccharides, sodium alginate (ALG) and gum Arabic (GA), were used as coatings to stabilize the AgNPs and the compounds acted as models to study AgNP aggregation kinetics. The DLVO theory was used to quantitatively describe the interactions between the AgNPs. The stability of AgNPs was established using UV-Visible spectrophotometry, including unique information collected during the first seconds of the aggregaton process. Alginate coating resulted in a moderate stabilization of AgNPs in terms of critical coagulation concentration (~82mM NaCl) and a low dissolution of <10% total Ag in NaCl solutions up to 1M. Gum Arabic coated AgNPs were more strongly stabilized, with ~7-30% size increase up to 77mM NaCl, but only when the silver ion content initially present in solution was low (<10% total Ag). The ALG and GA coated AgNPs showed a strongly enhanced stability in natural fjord waters (ca. 5h required to reduce the area of the surface plasmon resonance band (SPRB) by two fold) compared with NaCl at an equivalent ionic strength (1-2min period for a two fold SPRB reduction). This is ascribed to a stabilizing effect from dissolved organic matter present in natural fjord waters. Interestingly, for AgNP-GA solutions with 40% of total silver present as unreacted silver ions in the NP stock solution, fast aggregation kinetics were observed in NaCl solutions (SPRB area was reduced by ca. 50% within 40-150min), with even more rapid removal in fjord waters, attributed to the high amount of silver-chloride charged species, that interact with the NP coating and/or organic matter and reduce the NPs stabilization.

  19. Surface-enhanced Raman scattering from Ag nanoparticles formed by visible laser irradiation of thermally annealed AgO{sub x} thin films

    SciTech Connect

    Fujimaki, Makoto; Awazu, Koichi; Tominaga, Junji; Iwanabe, Yasuhiko

    2006-10-01

    Visible laser irradiation of AgO{sub x} thin films forms Ag nanoparticles, which then results in surface-enhanced Raman scattering (SERS). The efficiency of this Ag nanoparticle formation strongly depends on the properties of the AgO{sub x} thin films. Thermal annealing causes changes in physical properties such as deoxidization of the films and aggregation of Ag atoms in the films. In the present research, the effects of the changes induced by thermal annealing on SERS efficiency were examined. It was found that AgO{sub x} thin films annealed at 300 deg. C for 5 min in a N{sub 2} atmosphere were suitable for the formation of Ag nanoparticles effective for SERS, while films that were not annealed were not. From these results, it was deduced that the Ag aggregation resulting from thermal annealing in AgO{sub x} thin films promotes the Ag nanoparticle formation.

  20. Tensile and fatigue behaviors of printed Ag thin films on flexible substrates

    SciTech Connect

    Sim, Gi-Dong; Won, Sejeong; Lee, Soon-Bok

    2012-11-05

    Flexible electronics using nanoparticle (NP) printing has been highlighted as a key technology enabling eco-friendly, low-cost, and large-area fabrication. For NP-based printing to be used as a successive alternative to photolithography and vacuum deposition, stretchability and long term reliability must be considered. This paper reports the stretchability and fatigue behavior of 100 nm thick NP-based silver thin films printed on polyethylene-terephthalate substrate and compares it to films deposited by electron-beam evaporation. NP-based films show stretchability and fatigue life comparable to evaporated films with intergranular fracture as the dominant failure mechanism.

  1. Characterization of the Ag/YBa2Cu3O(7-x) contact in thin films

    NASA Astrophysics Data System (ADS)

    Jia, Q. X.; Anderson, W. A.; Zheng, J. P.; Zhu, Y. Z.; Patel, S.

    1990-12-01

    Ag contacts to very thin superconducting YBa2Cu3O(7-x) films were prepared by thermal evaporation. The nature of the Ag/YBa2Cu3O(7-x) contact during thermal treatment was in situ investigated by a combination of three- and four-terminal resistance measurements. The experimental results suggested that the interaction between Ag and the YBa2Cu3O(7-x) film began at a temperature of around 370 C. The lack of reproducibility in forming a low-resistance contact to very thin YBa2Cu3O(7-x) films and the high probability of degrading the film quality after thermal treatment of the contact might be due to the excess Ag doping in YBa2Cu3O(7-x). Ag island formation, as revealed by SEM after thermal treatment of the contact, is a limitation of Ag for use as a good contact electrode for very thin superconducting films.

  2. Ferroelectric domain of epitaxial AgNbO3 thin film

    NASA Astrophysics Data System (ADS)

    Ahn, Yoonho; Seo, Jeongdae; Lee, Kwang Jo; Son, Jong Yeog

    2016-03-01

    We investigated ferroelectric properties of silver niobate (AgNbO3) thin film grown on Nb-doped SrTiO3 substrate by pulsed laser deposition. The AgNbO3 thin film exhibited room temperature ferroelectricity with a large remanent polarization of about 31 μC/cm2 (2Pr~62 μC/cm2) and fast switching behavior within 120 ns. Triangular grains of AgNbO3 thin film were observed by atomic force microscopy (AFM). The piezoelectric force microscopy (PFM) study revealed that the AgNbO3 thin film had mosaic-like ferroelectric domain structure. In comparison with PbTiO3 thin films, domain size of the AgNbO3 thin films was smaller than that of PbTiO3 thin films. Based on Landau, Lifshitz, and Kittel (LLK) scaling law of the domain size versus film thickness curves, it is inferred that AgNbO3 thin films have slightly lower domain wall energy than that of PbTiO3 thin films.

  3. Evenly distributed thin-film Ag coating on stainless plate by tricomponent Ag/silicate/PU with antimicrobial and biocompatible properties.

    PubMed

    Huang, Yi-Hsiu; Chen, Mark Hung-Chih; Lee, Bing-Heng; Hsieh, Kuo-Huang; Tu, Yuan-Kun; Lin, Jiang-Jen; Chang, Chih-Hao

    2014-11-26

    A tricomponent nanohybrid dispersion in water comprising silver nanoparticles (AgNP), nanometer-thick silicate platelets (NSP), and water-based polyurethane (PU) was developed for surface coating on orthopedic metal plates. The previously developed AgNP-on-NSP nanohybrid was homogeneously blended into a selected waterborne PU dispersion at varied weight ratios from 1/0.1 to 1/10 (w/w). PU was used to adhere the Ag nanohybrid to the metal surface. The resultant dispersions were analyzed and found to contain AgNP 2-18 nm in diameter and characterized by using UV absorption and TEM micrograph. The subsequent coating of AgNP/NSP-PU dispersion generated a film of 1.5 μm thickness on the metal plate surface, further characterized by an energy dispersive spectroscope (EDS) to show the homogeneous distribution of Ag, Si, and C elements on the metal plates. The surface antimicrobial efficacy was proven for the coating composition of AgNP/NSP to PU ranging from 1/1 to 1/5 by weight ratio but irrelevant to the thickness of the coated materials. The metal plate coated with the high Ag content at 1/1 (w/w) ratio was shown to have very low cytotoxicity toward the contacted mammal fibroblasts. Overall, the optimized tricomponent Ag/silicate/PU in water dispersion from 1/2 to 1/3 (w/w) could generate a stable film on a metal surface exhibiting both antimicrobial and biocompatible properties. The facile coating technique of the AgNP/NSP in waterborne PU is proven to be viable for fabricating infection- and cytotoxicity-free medical devices.

  4. Structure and bonding in photodiffused amorphous Ag-GeSe/sub 2/ thin films

    SciTech Connect

    Fischer-Colbrie, A.; Bienenstock, A.; Fuoss, P.H.; Marcus, M.A.

    1988-12-15

    Grazing-incidence x-ray scattering (GIXS) techniques have been used to study the local and intermediate-range order in photodiffused amorphous Ag-GeSe/sub 2/ thin films and a variety of Ag-Ge-Se alloys. Using synchrotron-radiation sources, the GIXS technique can be used in conjunction with radial-distribution-function analysis, differential anomalous x-ray scattering, and differential distribution-function analysis to study the structure of very thin amorphous films. With these techniques, we have determined that the local atomic structure of Ag-GeSe/sub 2/ films satisfies a model where Se-Ag dative bonds are formed, one Se-Ag covalent bond is formed for each Ag atom added (below a critical composition), and Ge-Ge bonds are created as Ag is added. This last result significantly modifies the intermediate-range order in this system.

  5. Photocurrent enhancement of chemically synthesized Ag nanoparticle-embedded BiFeO3 thin films

    NASA Astrophysics Data System (ADS)

    Maruyama, Rika; Sakamoto, Wataru; Yuitoo, Isamu; Takeuchi, Teruaki; Hayashi, Koichiro; Yogo, Toshinobu

    2016-10-01

    BiFeO3 and Ag nanoparticle-embedded BiFeO3 thin films were prepared on Pt/TiO x /SiO2/Si and MgO(100) substrates using colloidal silver and BiFeO3 metal-organic precursor solutions. Colloidal silver solution was prepared by a chemical reductive method using NaBH4 as a reductant. The prepared Ag nanoparticles exhibited characteristic optical absorption properties based on their surface plasmon resonance related to particle size. The synthesized BiFeO3 and Ag nanoparticle/BiFeO3 thin films demonstrated rapid on/off responses of photocurrent to visible light. The Ag nanoparticle-incorporated BiFeO3 film exhibited a 2-4-fold higher photocurrent than the BiFeO3 film. Optical and ferroelectric properties did not change markedly even when Ag nanoparticles were embedded in the BiFeO3 thin film within the quantities of this study. Furthermore, in the Ag nanoparticle/BiFeO3 composite structure, Ag nanoparticles were introduced in the near-metallic state with maintained their nanometer size. In the Ag nanoparticle-embedded BiFeO3 film, photoinduced charge separation and transport of photoexcited carriers were enhanced by the surface plasmon effect of nanosized Ag particles as well as the internal bias electric field existed in the narrow-bandgap BiFeO3 thin film.

  6. Ag Nanodots Emitters Embedded in a Nanocrystalline Thin Film Deposited on Crystalline Si Solar Cells.

    PubMed

    Park, Seungil; Ryu, Sel Gi; Ji, HyungYong; Kim, Myeong Jun; Peck, Jong Hyeon; Kim, Keunjoo

    2016-06-01

    We fabricated crystalline Si solar cells with the inclusion of various Ag nanodots into the additional emitters of nanocrystallite Si thin films. The fabricated process was carried out on the emitter surface of p-n junction for the textured p-type wafer. The Ag thin films were deposited on emitter surfaces and annealed at various temperatures. The amorphous Si layers were also deposited on the Ag annealed surfaces by hot-wire chemical vapor deposition and then the deposited layers were doped by the second n-type doping process to form an additional emitter. From the characterization, both the Ag nanodots and the deposited amorphous Si thin films strongly reduce photo-reflectances in a spectral region between 200-400 nm. After embedding Ag nanodots in nanocrystallite Si thin films, a conversion efficiency of the sample with added emitter was achieved to 15.1%, which is higher than the 14.1% of the reference sample and the 14.7% of the de-posited sample with a-Si:H thin film after the Ag annealing process. The additional nanocrystallite emitter on crystalline Si with Ag nanodots enhances cell properties. PMID:27427665

  7. Antibacterial activity of microstructured Ag/Au sacrificial anode thin films.

    PubMed

    Köller, Manfred; Sengstock, Christina; Motemani, Yahya; Khare, Chinmay; Buenconsejo, Pio J S; Geukes, Jonathan; Schildhauer, Thomas A; Ludwig, Alfred

    2015-01-01

    Ten different Ag dot arrays (16 to 625 microstructured dots per square mm) were fabricated on a continuous Au thin film and for comparison also on Ti film by sputter deposition and photolithographic patterning. To analyze the antibacterial activity of these microstructured films Escherichia coli and Staphylococcus aureus were placed onto the array surfaces and cultivated overnight. To analyze the viability of planktonic as well as surface adherent bacteria, the applied bacterial fluid was subsequently aspirated, plated on blood agar plates and adherent bacteria were detected by fluorescence microscopy. A particular antibacterial effect towards both bacterial strains was induced by Ag dot arrays on fabricated Au thin film (sacrificial anode system for Ag), due to the release of Ag ions from dissolution of Ag dots in contrast to Ag dot arrays fabricated on the Ti thin films (non-sacrificial anode system for Ag) which remained intact to the original dot shape. The required number of Ag dots on gold film to achieve complete bactericidal effects for both bacterial strains was seven times lower than that observed with Ag dot arrays on Ti film.

  8. Chemically-inactive interfaces in thin film Ag/AgI systems for resistive switching memories

    PubMed Central

    Cho, Deok-Yong; Tappertzhofen, Stefan; Waser, Rainer; Valov, Ilia

    2013-01-01

    AgI nanoionics-based resistive switching memories were studied in respect to chemical stability of the Ag/AgI interface using x-ray absorption spectroscopy. The apparent dissolution of Ag films of thickness below some tens of nanometers and the loss of electrode/electrolyte contact was critically addressed. The results evidently show that there are no chemical interactions at the interface despite the high ionic mobility of Ag ions. Simulation results further show that Ag metal clusters can form in the AgI layer with intermediate-range order at least up to next-next nearest neighbors, suggesting that Ag can permeate into the AgI only in an aggregated form of metal crystallite. PMID:23378904

  9. The mechanism of Ag top layer on the coercivity enhancement of FePt thin films

    SciTech Connect

    Zhao, Z.L.; Ding, J.; Yi, J.B.; Chen, J.S.; Zeng, J.H.; Wang, J.P.

    2005-05-15

    The magnetic properties of the FePt thin films with a Ag top layer prepared by magnetron sputtering have been studied. With 4 nm Ag layer deposited right after the deposition of FePt layer, the ordering temperature of the L1{sub 0} FePt phase decreased to 350 deg. C or below. X-ray photoelectron spectroscopy results indicate that Ag has diffused into the FePt layer when Ag was deposited at 350 deg. C, while Ag remains on the top of the FePt when Ag was deposited at room temperature. The Ag top layer deposited at 350 deg. C was also found to protect the FePt layer from oxidation.

  10. Spoof-like plasmonic behavior of plasma enhanced atomic layer deposition grown Ag thin films

    SciTech Connect

    Prokes, S. M.; Glembocki, O. J.; Cleveland, Erin; Caldwell, Josh D.; Foos, Edward; Niinistoe, Jaakko; Ritala, Mikko

    2012-01-30

    The plasmonic behavior of Ag thin films produced by plasma enhanced atomic layer deposition (PEALD) has been investigated. We show that as-deposited flat PEALD Ag films exhibit unexpected plasmonic properties, and the plasmonic enhancement can differ markedly, depending on the microstructure of the Ag film. Electromagnetic field simulations indicate that this plasmonic behavior is due to air gaps that are an inherent property of the mosaic-like microstructure of the PEALD-grown Ag film, suggesting that this is a metamaterial with behavior very similar to what would be expected in spoof plasmonics where gaps are fabricated in films to create plasmonic-like resonances.

  11. Tuning the SERS Response with Ag-Au Nanoparticle-Embedded Polymer Thin Film Substrates.

    PubMed

    Rao, V Kesava; Radhakrishnan, T P

    2015-06-17

    Development of facile routes to the fabrication of thin film substrates with tunable surface enhanced Raman scattering (SERS) efficiency and identification of the optimal conditions for maximizing the enhancement factor (EF) are significant in terms of both fundamental and application aspects of SERS. In the present work, polymer thin films with embedded bimetallic nanoparticles of Ag-Au are fabricated by a simple two-stage protocol. Ag nanoparticles are formed in the first stage, by the in situ reduction of silver nitrate by the poly(vinyl alcohol) (PVA) film through mild thermal annealing, without any additional reducing agent. In the second stage, aqueous solutions of chloroauric acid spread on the Ag-PVA thin film under ambient conditions, lead to the galvanic displacement of Ag by Au in situ inside the film, and the formation of Ag-Au particles. Evolution of the morphology of the bimetallic nanoparticles into hollow cage structures and the distribution of Au on the nanoparticles are revealed through electron microscopy and energy dispersive X-ray spectroscopy. The localized surface plasmon resonance (LSPR) extinction of the nanocomposite thin film evolves with the Ag-Au composition; theoretical simulation of the extinction spectra provides insight into the observed trends. The Ag-Au-PVA thin films are found to be efficient substrates for SERS. The EF follows the variation of the LSPR extinction vis-à-vis the excitation laser wavelength, but with an offset, and the maximum SERS effect is obtained at very low Au content; experiments with Rhodamine 6G showed EFs on the order of 10(8) and a limit of detection of 0.6 pmol. The present study describes a facile and simple fabrication of a nanocomposite thin film that can be conveniently deployed in SERS investigations, and the utility of the bimetallic system to tune and maximize the EF.

  12. Characterization of radiative recombination in Ag(In,Ga)Se2 thin films by photoluminescence

    NASA Astrophysics Data System (ADS)

    Zhang, X. F.; Liu, J.; Liu, G. F.

    2016-06-01

    A detailed analysis of the radiative recombination processes in Ag(InGa)Se2 thin films grown by a three-stage method was carried out by photoluminescence. The temperature and excitation dependence of the photoluminescence spectra was used to identify the recombination types and determine the ionization energy of the defects in the films. Significant differences were observed between the spectra of the Ag-rich and Ag-poor samples. The Ag-rich films were dominated by two emission peaks of donor acceptor pairs (DAPs). The DAP at lower energy level is attributed to recombination of donor level 13.8 meV (Agi) with acceptor level 70.3 meV (AgIn), while the one at high energy level is assigned to recombination of donor level 18.5 meV (Agi) with acceptor level 108.9 (AgSe). When Ag/III atomic ratio was near 2.00, a phonon related-structure began to appear, which is attributed to the phonon replica of the high energy level DAP. In the case of Ag-poor AIGS samples, the dominant broad asymmetric peaks of AIGS films with different Ag/III atomic ratios were related to potential fluctuation at low temperature, and the compensation level decreased with increasing Ag/III atomic ratio. The emission line was assigned to recombination of donor level 12.7 meV (Agi) with acceptor level 175 meV ( AgGa 2). When the excitation power and temperature were increased, new free-bound and DAP emission lines began to appear. The free-bound was assigned to the transition from the conduction band to an acceptor level of 80 meV (AgIn). The DAP was assigned to recombination of donor level 20 meV (VSe) with acceptor level 145 meV (AgGa).

  13. Ag nanoparticle dispersed PbTiO3 percolative composite thin film with high permittivity

    NASA Astrophysics Data System (ADS)

    Wang, Zongrong; Hu, Tao; Tang, Liwen; Ma, Ning; Song, Chenlu; Han, Gaorong; Weng, Wenjian; Du, Piyi

    2008-12-01

    Ag nanoparticle dispersed PbTiO3 percolative composite thin films were prepared in situ by sol-gel method using Pb(NO3)2, Ti(C4H9O)4, and AgNO3 as raw materials and lactic acid along with citric acid as complexing agent. The size of the Ag nanoparticles measured by ultraviolet-visible spectra is about 3nm. The percolation effect occurs in composite thin films. The composite exhibits relatively high dielectric constant which is about five times higher than that of PbTiO3 thin film and comparatively low dielectric loss comparable to pure PbTiO3 system. It is highly attractive in application of high quality dielectric devices and miniaturization.

  14. Tuning the Stoichiometry of Ag2S Thin Films for Resistive Switching Applications.

    PubMed

    Dias, C; Proenca, M P; Fernandes, L; Tavares, P B; Vilarinho, R; Moreira, J Agostinho; Araújo, J P; Ventura, J

    2016-03-01

    In this work silver-rich and sulfur-rich silver sulfide (Ag2S) thin films were fabricated using a diversified set of experimental methods, namely ion beam deposition and atmosphere- and solution-based sulfurizations. The composition of the Ag2S thin films was studied using X-ray diffraction, Raman spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. We found that it strongly depends on the fabrication conditions, such as sulfurization time and temperature. These conditions, in turn, affect the electrical characteristics of the thin films, namely the resistivity and resistive switching. We were able to control the Ag2S stoichiometry and infer its dependence on the fabrication parameters for all the followed methods.

  15. Patterned PPy Polymer and PPy/Ag Nanocomposites Thin Films by Photo-DLICVD

    NASA Astrophysics Data System (ADS)

    Manole, C. C.; Maury, F.; Demetrescu, I.

    This work deals with the deposition of both undoped (insulator) and extrinsically Ag-doped (conductive) polypyrrole (PPy) coatings by an original Photo-DLICVD process. The uniform and conformal coverage of PPy thin films on both Si(100) wafer and liquid micro-droplets forming blisters is investigated. A self-ordered surface patterning of the blisters is achieved and discussed in relation with the substrate nature. By changing the precursor chemistry in this CVD process, conductive PPy/Ag nanocomposite films are grown. First evidence for conductive behavior of these Ag-doped PPy coatings was found. The Ag nanoparticles (NPs) reveal 1D assembly at the ledges of crystal-like facets of micron size nanocomposite particles leading to more complex arrangements of the metal NPs in the hybrid PPy/Ag coatings.

  16. Speciation and Lability of Ag-, AgCl- and Ag2S-Nanoparticles in Soil Determined by X-ray Absorption Spectroscopy and Diffusive Gradients in Thin Films

    EPA Science Inventory

    Long-term speciation and lability of silver (Ag-), silver chloride (AgCl-) and silver sulfide nanoparticles (Ag2S-NPs) in soil were studied by X-ray absorption spectroscopy (XAS), and newly developed "nano" Diffusive Gradients in Thin Films (DGT) devices. These nano-D...

  17. Chemical and phase distributions in a multilayered organic matter-Ag nanoparticle thin film system

    NASA Astrophysics Data System (ADS)

    Michel, F. M.; Levard, C.; Wang, Y.; Choi, Y.; Eng, P.; Brown, G. E.

    2010-12-01

    Rapid development of nanotechnologies raises concern regarding the environmental impact of nanoparticles on ecosystems. Among the types of nanoparticles currently in production, metallic silver is the most widely used in nanotechnology (1). Synthetic Ag nanoparticles (Ag-NPs) are most often used for their antimicrobial and antifungal properties that are, in part, explained by the release of highly toxic Ag+ species (2). While such properties are desirable in certain applied cases, the release of Ag-NPs and soluble Ag+ species to the environment is expected to impact biota as well as soil and water quality (3). With the production of Ag-NPs projected to increase (1), the amount of Ag-NPs that will be released to the environment through waste streams is also likely to increase. As such, a deeper understanding of the fundamental processes associated with Ag-NPs toxicity and reactivity is needed to evaluate their impact on the environment. We have studied the interaction during aging of poly-acrylic acid (PAA) and Ag-NPs with average particle sizes of 20 ±5 nm. The sample studied was composed of thin films of PAA and Ag-NPs deposited on a Si-wafer support. PAA served as a model compound and a simplified surrogate for exopolysaccharide, an organic substance produced through metabolic activity by most microorganisms. We applied a novel combination of long-period x-ray standing wave fluorescence yield (XSW-FY) spectroscopy, grazing-incidence x-ray diffraction (GI-XRD), and XRD-based standing wave profiles (XSW-XRD) to obtain chemical- and phase-specific information on this sample. After 24 hours, we observed the formation of AgCl(s) in the PAA film of the sample, which suggests oxidation and dissolution of a portion of the Ag-NPs during aging, resulting in the release of Ag+. In addition, we see partitioning of Cl and Br, both present initially in the PAA, to the intact Ag-NPs thin film. To our knowledge, this is the first application of this suite of techniques to this

  18. SEMICONDUCTOR DEVICES: Ag/PEPC/NiPc/ZnO/Ag thin film capacitive and resistive humidity sensors

    NASA Astrophysics Data System (ADS)

    Karimov, Kh. S.; Yew Cheong, Kuan; Saleem, M.; Murtaza, Imran; Farooq, M.; Fauzi Mohd Noor, Ahmad

    2010-05-01

    A thin film of blended poly-N-epoxypropylcarbazole (PEPC) (25 wt.%), nickel phthalocyanine (NiPc) (50 wt.%) and ZnO nano-powder (25 wt.%) in benzene (5 wt.%) was spin-coated on a glass substrate with silver electrodes to produce a surface-type Ag/PEPC/NiPc/ZnO/Ag capacitive and resistive sensor. Sensors with two different PEPC/NiPc/ZnO film thicknesses (330 and 400 nm) were fabricated and compared. The effects of humidity on capacitance and resistance of the Ag/PEPC/NiPc/ZnO/Ag sensors were investigated at two frequencies of the applied voltage: 120 Hz and 1 kHz. It was observed that at 120 Hz under humidity of up to 95% RH the capacitance of the sensors increased by 540 times and resistance decreased by 450 times with respect to humidity conditions of 50% RH. It was found that the sensor with a thinner semiconducting film (330 nm) was more sensitive than the sensor with a thicker film (400 nm). The sensitivity was improved when the sensor was used at a lower frequency as compared with a high frequency. It is assumed that the humidity response of the sensors is associated with absorption of water vapors and doping of water molecules in the semiconductor blend layer. This had been proven by simulation of the capacitance-humidity relationship.

  19. Preparation of vanadium oxide thin films modified with Ag using a hybrid deposition configuration

    NASA Astrophysics Data System (ADS)

    Gonzalez-Zavala, F.; Escobar-Alarcón, L.; Solís-Casados, D. A.; Rivera-Rodríguez, C.; Basurto, R.; Haro-Poniatowski, E.

    2016-04-01

    The application of a hybrid deposition configuration, formed by the interaction of a laser ablation plasma with a flux of atomic vapor, to deposit vanadium oxide thin films modified with different amounts of silver, is reported. The effect of the amount of Ag incorporated in the films on their structural, morphological, compositional and optical properties was studied. The obtained results reveal that films with variable Ag content from 11.7 to 24.6 at.% were obtained. Depending on the silver content, the samples show very different surface morphologies. Optical characterization indicates the presence of nanostructures of Ag. Thin films containing silver exhibit better photocatalytic performances than unmodified V2O5 films. Raman spectra reveal that as the silver content is increased, the signals associated with V2O5 disappear and new modes attributed mainly to silver vanadates appear suggesting the formation of ternary compounds.

  20. Influence of Ag doping concentration on structural and optical properties of CdS thin film

    SciTech Connect

    Kumar, Pragati; Saxena, Nupur; Gupta, Vinay; Agarwal, Avinash

    2015-05-15

    This work shows the influence of Ag concentration on structural properties of pulsed laser deposited nanocrystalline CdS thin film. X-ray photoelectron spectroscopy (XPS) studies confirm the dopant concentration in CdS films and atomic concentration of elements. XPS studies show that the samples are slightly sulfur deficient. GAXRD scan reveals the structural phase transformation from cubic to hexagonal phase of CdS without appearance of any phase of CdO, Ag{sub 2}O or Ag{sub 2}S suggesting the substitutional doping of Ag ions. Photoluminescence studies illustrate that emission intensity increases with increase in dopant concentration upto 5% and then decreases for higher dopant concentration.

  1. Deposition of Pd–Ag thin film membranes on ceramic supports for hydrogen purification/separation

    SciTech Connect

    Pereira, A.I.; Pérez, P.; Rodrigues, S.C.; Mendes, A.; Madeira, L.M.

    2015-01-15

    Highlights: • Thin film Pd–Ag membranes have been produced for hydrogen selectivity. • Magnetron sputtering yields Pd–Ag compact films for atomic H diffusion. • The thin film Pd–Ag membranes yielded a selectivity of α (H{sub 2}/N{sub 2}) = 10. - Abstract: Pd–Ag based membranes supported on porous α-Al{sub 2}O{sub 3} (doped with yttria-stabilized zirconia) were studied for hydrogen selective separation. Magnetron sputtering technique was employed for the synthesis of thin film membranes. The hydrogen permeation flux is affected by the membrane columnar structure, which is formed during deposition. From scanning electron microscopy analysis, it was observed that different sputtering deposition pressures lead to distinct columnar structure growth. X-ray diffraction patterns provided evidence of a Pd–Ag solid solution with an average crystallite domain size of 21 nm, whose preferential growth can be altered by the deposition pressure. The gas-permeation results have shown that the Pd–Ag membrane supported on porous α-Al{sub 2}O{sub 3} is selective toward H{sub 2}. For optimized membrane synthesis conditions, the permeance toward N{sub 2} is 0.076 × 10{sup −6} mol m{sup −2} s{sup −1} Pa{sup −1} at room temperature, whereas for a pressure difference of 300 kPa the H{sub 2}-flux is of the order of ca. 0.21 mol m{sup −2} s{sup −1}, which corresponds to a permeance of 0.71 × 10{sup −6} mol m{sup −2} s{sup −1} Pa{sup −1}, yielding a selectivity of α (H{sub 2}/N{sub 2}) = 10. These findings suggest that the membrane has a reasonable capacity to selectively permeate this gas.

  2. Critical current behavior of Ag-coated YBa2Cu3O(7-x) thin films

    NASA Astrophysics Data System (ADS)

    Ono, R. H.; Beall, J. A.; Harvey, T. E.; Reintsema, C. D.; Johansson, M.

    1991-03-01

    The authors studied the behavior of high-quality YBa2Cu3O(7-x) (YBCO) thin films with Ag overlayers. The authors chose to study Ag in detail because of its widespread use as contact metallization and because of their earlier studies of proximity effects in YBCO. The details of transport critical current measurements are presented. It is shown that the Ag coatings can reduce normal state resistance while not degrading the critical current density. The key technological result is that the various thicknesses of Ag that were used did not reduce Jc or Jc(H). Critical current densities in excess of 106 A/sq cm have been achieved at temperatures greater than 76 K. An unusual effect was seen in Jc(H) when the field was oriented perpendicular to the c axis of the film. The Jc at 1 T was higher in samples with 10-nm coatings of Ag than in similar uncoated samples. It was also shown that the composite resistance of Ag-YBCO bilayers can be much lower than the resistance of uncoated YBCO.

  3. Linear magnetoresistance in Ag2+δSe thin films

    NASA Astrophysics Data System (ADS)

    von Kreutzbruck, M.; Lembke, G.; Mogwitz, B.; Korte, C.; Janek, J.

    2009-01-01

    In the nonstoichiometric low-temperature phase of silver selenide a very small silver excess within the semiconducting silver selenide matrix in the order of 0.01% is sufficient to generate a linear magnetoresistance (LMR) of more than 300% at 5 T, which does not saturate at fields up to 60 T. Different theoretical models have been proposed to explain this unusual magnetoresistance (MR) behavior, among them a random resistor network consisting of four-terminal resistor units. According to this model the LMR and the crossover field from linear to quadratic behavior are primarily controlled by both the spatial distribution of the charge-carrier mobility and its average value, being essentially functions of the local and average compositions. Here we report measurements on silver-rich thin AgxSe films with a thickness between 20 nm and 2μm , which show an increasing average mobility in conjunction with an enhanced MR for increasing film thickness. We found a linear scaling between the size of the transverse LMR and the crossover field, as predicted by the theory. For films thinner than about 100 nm the MR with field directed in the sample plane shows a breakdown of the LMR, revealing the physical length scale of the inhomegeneities in thin AgxSe devices.

  4. Sputtered Ag thin films with modified morphologies: Influence on wetting property

    NASA Astrophysics Data System (ADS)

    Dutheil, P.; Thomann, A. L.; Lecas, T.; Brault, P.; Vayer, M.

    2015-08-01

    Silver thin films with thickness ranging from 3 nm to 33 nm were sputter deposited onto silicon wafers and tungsten layers. Those W layers were previously synthesized in the same DC magnetron sputter deposition system with various experimental conditions (argon pressure, target to substrate distance) in order to stabilize different surface morphologies. SEM observations and AFM images showed that the growth mode of Ag films is similar on Si substrates and on the smoothest W layers, whereas it is modified for rough W layers made of sharp grains. The effect of the W layer morphology on Ag film growth was clearly evidenced when the deposition took place at high temperature. It is seen that performing the deposition onto substrates of various morphologies allows tailoring the wetting property of the Ag deposit.

  5. Influence of the preparation method on the As-Se-AgI thin films behaviour

    NASA Astrophysics Data System (ADS)

    Hineva, T.; Petkova, T.; Petkov, P.; Mikli, V.; Socol, G.; Mihailescu, C. N.; Mihailescu, I. N.

    2008-05-01

    Bulk glasses of the (As2Se3)1-x (AgI)x and (AsSe)1-x(AgI)x systems, where x = 5, 10, 15 up to 35 mol.% have been prepared by the melt-quenched technique. The thin films have been deposited by means of vacuum thermal evaporation (VTE) and pulsed laser deposition (PLD). The XRD investigation reveals a generally amorphous structure; small peaks are only observed in the samples with the highest AgI. The film compositions have been determined by EDS (energy dispersive X-ray microanalysis). WDS (wavelength dispersive spectroscopy) studies have shown that the films do not contain oxygen within the accuracy of the method (1 %). The films are dense with smooth surface as revealed by using scanning electron microscopy (SEM) and atomic force microscopy (AFM).

  6. Preparation of AgInS{sub 2} chalcopyrite thin films by chemical spray pyrolysis

    SciTech Connect

    Ortega-Lopez, M.; Vigil-Galan, O.; Cruz Gandarilla, F.; Solorza-Feria, O

    2003-01-01

    AgInS{sub 2} thin films were prepared by the spray pyrolysis technique using a water/ethanol solution containing silver acetate, indium chloride and thiourea. We reported our results on the characterization of tetragonal AgInS{sub 2} (chalcopyrite type) films, which were grown from indium deficient spraying solution. The films displayed a n-type conductivity with room temperature resistivities in the range between 10{sup 3} and 10{sup 4} {omega} cm. The absorption spectra of sprayed films revealed two direct band-gaps with characteristic energies around 1.87 and 2.01 eV, which are in good agreement with the reported energy values for interband transitions from the split p-like valence band to the s-like conduction band in tetragonal AgInS{sub 2} single crystals.

  7. Structural and optical studies on AgSbSe{sub 2} thin films

    SciTech Connect

    Asokan, T. Namitha; Urmila, K. S.; Pradeep, B.

    2014-01-28

    AgSbSe{sub 2} semiconducting thin films are successfully deposited using reactive evaporation technique at a substrate temperature of 398K. X-ray diffraction studies reveal that the films are polycrystalline in nature. The structural parameters such as average particle size, dislocation density, and number of crystallites per unit have been evaluated. Atomic Force Microscopy is used to study the topographic characteristics of the film including the grain size and surface roughness. The silver antimony selenide thin films have high absorption coefficient of about 10{sup 5} cm{sup −1} and it has an indirect band gap of 0.64eV.

  8. Superhydrophobic Ag decorated ZnO nanostructured thin film as effective surface enhanced Raman scattering substrates

    NASA Astrophysics Data System (ADS)

    Jayram, Naidu Dhanpal; Sonia, S.; Poongodi, S.; Kumar, P. Suresh; Masuda, Yoshitake; Mangalaraj, D.; Ponpandian, N.; Viswanathan, C.

    2015-11-01

    The present work is an attempt to overcome the challenges in the fabrication of super hydrophobic silver decorated zinc oxide (ZnO) nanostructure thin films via thermal evaporation process. The ZnO nanowire thin films are prepared without any surface modification and show super hydrophobic nature with a contact angle of 163°. Silver is further deposited onto the ZnO nanowire to obtain nanoworm morphology. Silver decorated ZnO (Ag@ZnO) thin films are used as substrates for surface enhanced Raman spectroscopy (SERS) studies. The formation of randomly arranged nanowire and silver decorated nanoworm structure is confirmed using FESEM, HR-TEM and AFM analysis. Crystallinity and existence of Ag on ZnO are confirmed using XRD and XPS studies. A detailed growth mechanism is discussed for the formation of the nanowires from nanobeads based on various deposition times. The prepared SERS substrate reveals a reproducible enhancement of 3.082 × 107 M for Rhodamine 6G dye (R6G) for 10-10 molar concentration per liter. A higher order of SERS spectra is obtained for a contact angle of 155°. Thus the obtained thin films show the superhydrophobic nature with a highly enhanced Raman spectrum and act as SERS substrates. The present nanoworm morphology shows a new pathway for the construction of semiconductor thin films for plasmonic studies and challenges the orderly arranged ZnO nanorods, wires and other nano structure substrates used in SERS studies.

  9. Properties of cathodic arc deposited high-temperature superconducting composite thin films on Ag substrates

    NASA Astrophysics Data System (ADS)

    Chae, M. S.; Simnad, M. T.; Maple, M. B.; Anders, S.; Anders, A.; Brown, I. G.

    1996-02-01

    High temperature superconducting composite thin films on Ag substrates were prepared by cathodic arc deposition of alloy precursors. The deposition technique employed a cathode comprised of a precursor alloy for the vacuum arc plasma source. The precursor alloy was prepared by multiple arc-melting of mixed metallic constituents of the high-temperature superconducting material Bi 2Sr 2CaCu 2O y (Bi2212) and 50 wt.% of Ag. The presence of silver in the precursor alloy film was expected to allow accommodation of the lattice and thermal expansion mismatch between the oxidized film and the silver substrate. The as-deposited film could be formed to practically any desirable shape before being subjected to heat treatments. Following deposition, controlled oxidation of the precursor alloy thin film on the Ag substrate was performed to produce the superconducting composite on the silver substrate. After the heat treatment, the composite film consisted of Bi2212 highly c-axis oriented normal to the Ag substrate.

  10. Effect of Grazing Angle Cross-Ion Irradiation on Ag Thin Films

    NASA Astrophysics Data System (ADS)

    Kumar, Manish; Jangid, Teena; Panchal, Vandana; Kumar, Praveen; Pathak, Abhishek

    2016-10-01

    Apart from the spherical shape, control over other shapes is a technical challenge in synthesis approaches of nanostructures. Here, we studied the effect of grazing angle cross-irradiation Ag thin films for the nanostructures evolution from a top-down approach. Ag thin films of different thicknesses were deposited on Si (100) and glass substrates by electron beam evaporation system and subsequently irradiated at grazing angle ions by 80 keV Ar+ in two steps (to induce effectively a cross-ion irradiation). Pristine films exhibited dense and uniform distribution of Ag nanoparticles with their characteristic surface plasmon resonance-induced absorption peak around 420 nm. When the film surfaces were treated with cross-grazing angle irradiation of Ar ions with varying effective fluences from 0.5 × 1017 ions/cm2 to 2.0 × 1017 ions/cm2, it was found that fluence values governed the competition of sputtering and sputter re-deposition of Ag. As a result, lower irradiation fluence favoured the formation of cone-like nanostructures, whereas high fluence values demonstrated dominant sputtering. Fluence-dependent modification of surface features was studied through the Fourier transform infrared spectroscopy and the Rutherford backscattering spectroscopy. Theoretical justifications for the underlying mechanisms are presented to justify the experimental results.

  11. One step 'dip' and 'use' Ag nanostructured thin films for ultrahigh sensitive SERS Detection.

    PubMed

    Rajkumar, Kanakaraj; Jayram, Naidu Dhanpal; Mangalaraj, Devanesan; Rajendra Kumar, Ramasamy Thangavelu

    2016-11-01

    A simple one step galvanic displacement method which involves dipping of the silicon substrate in the AgNO3/HF solution and using it for SERS application without any further process is demonstrated. The size and shape of the Ag nanoparticles changes as the deposition time is increased. Initially the shape of the particles was nearly spherical and as it grows, becomes oblong and then coalesce to form a discontinuous film with vertically grown hierarchical Ag nanostructures. The sizes of the deposited particles were in the ranges from 30nm to a discontinuous film. It also demonstrated a highly sensitive chemical detection by surface-enhanced Raman scattering of rhodamine 6G dye, down to 10(-16)M concentration. Prepared samples were able to detect lower concentrations of Melamine. Discontinuous thin films with hierarchical Ag nanostructures were obtained for 5min Ag deposition. The formation of Hot spots between the discontinuous islands and also along the hierarchical structures is responsible for the high SERS enhancement. This simple one step, fast, non-lithographic and cost effective method can be applied for various label free detection of analytes of importance.

  12. One step 'dip' and 'use' Ag nanostructured thin films for ultrahigh sensitive SERS Detection.

    PubMed

    Rajkumar, Kanakaraj; Jayram, Naidu Dhanpal; Mangalaraj, Devanesan; Rajendra Kumar, Ramasamy Thangavelu

    2016-11-01

    A simple one step galvanic displacement method which involves dipping of the silicon substrate in the AgNO3/HF solution and using it for SERS application without any further process is demonstrated. The size and shape of the Ag nanoparticles changes as the deposition time is increased. Initially the shape of the particles was nearly spherical and as it grows, becomes oblong and then coalesce to form a discontinuous film with vertically grown hierarchical Ag nanostructures. The sizes of the deposited particles were in the ranges from 30nm to a discontinuous film. It also demonstrated a highly sensitive chemical detection by surface-enhanced Raman scattering of rhodamine 6G dye, down to 10(-16)M concentration. Prepared samples were able to detect lower concentrations of Melamine. Discontinuous thin films with hierarchical Ag nanostructures were obtained for 5min Ag deposition. The formation of Hot spots between the discontinuous islands and also along the hierarchical structures is responsible for the high SERS enhancement. This simple one step, fast, non-lithographic and cost effective method can be applied for various label free detection of analytes of importance. PMID:27524085

  13. The role of Ag in the pulsed laser growth of YBCO thin films

    NASA Astrophysics Data System (ADS)

    Kalyanaraman, R.; Oktyabrsky, S.; Narayan, J.

    1999-05-01

    We have studied systematically the role of silver in improving microstructure and properties of Y1Ba2Cu3O7-δ (YBCO) thin films. We have more than doubled the grain size to nearly 1.8 μm and reduced processing temperatures by incorporating Ag in the YBCO films, which is accomplished by using a composite target containing 15% by weight of Ag. These films show approximately four times higher Jc than the best films obtained on MgO(001) substrates deposited from stoichiometric Y1Ba2Cu3O7-δ targets. Study of the silver content in the film as a function of the deposition temperature shows clearly a decreasing concentration with increasing temperature and a segregation of the Ag to the surface. The increased oxygen content in the films is also observed at lower processing temperatures, providing strong support for the efficient oxygenation of YBCO via the presence of silver. A qualitative model suggests that the formation of silver oxide, rapid surface diffusion of Ag on MgO surfaces, and the nonreactivity of Ag with YBCO are the key aspects to the improvement in microstructure. The possibility of extending these ideas to the growth of oxides is also discussed, along with the fabrication of in-situ superconducting-metal junctions with 3D geometries.

  14. Photoluminescence of SrS:Cu,Ag and SrS 1- xSe x:Cu,Ag thin films

    NASA Astrophysics Data System (ADS)

    Poelman, D.; Wauters, D.; Van Meirhaeghe, R. L.; Cardon, F.

    2000-01-01

    The photoluminescence (PL) of SrS:Cu,Ag and SrS 1- xSe x:Cu,Ag thin films has been investigated. The influence of rapid thermal annealing conditions and Cu dopant concentration on the PL intensity has been studied. The PL emission spectrum was measured as a function of both Cu concentration and temperature. An unexpected PL intensity peak was observed around a temperature of 54 K.

  15. Synthesis of Ag-TiO2 composite nano thin film for antimicrobial application.

    PubMed

    Yu, Binyu; Leung, Kar Man; Guo, Qiuquan; Lau, Woon Ming; Yang, Jun

    2011-03-18

    TiO2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO2 and Ag-TiO2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO2 and TiO2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag(0) state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm(-2) and in the dark respectively. The synthesized Ag-TiO2 thin films showed enhanced bactericidal activities compared to the neat TiO2 nanofilm both in the dark and under UV illumination.

  16. Systematic Surface Phase Transition of Ag Thin Films by Iodine Functionalization at Room Temperature: Evolution of Optoelectronic and Texture Properties.

    PubMed

    Bashouti, Muhammad Y; Talebi, Razieh; Kassar, Thaer; Nahal, Arashmid; Ristein, Jürgen; Unruh, Tobias; Christiansen, Silke H

    2016-01-01

    We show a simple room temperature surface functionalization approach using iodine vapour to control a surface phase transition from cubic silver (Ag) of thin films into wurtzite silver-iodid (β-AgI) films. A combination of surface characterization techniques (optical, electronical and structural characterization) reveal distinct physical properties of the new surface phase. We discuss the AgI thin film formation dynamics and related transformation of physical properties by determining the work-function, dielectric constant and pyroelectric behavior together with morphological and structural thin film properties such as layer thickness, grain structure and texture formation. Notable results are: (i) a remarkable increase of the work-function (by 0.9 eV) of the Ag thin layer after short a iodine exposure time (≤60 s), with simultaneous increase of the thin film transparency (by two orders of magnitude), (ii) pinning of the Fermi level at the valance band maximum upon iodine functionalization, (iii) 84% of all crystallites grain were aligned as a result of the evolution of an internal electric field. Realizing a nano-scale layer stack composed of a dielectric AgI layer on top of a metallic thin Ag layer with such a simple method has some technological implications e.g. to realize optical elements such as planar optical waveguides. PMID:26899434

  17. Systematic Surface Phase Transition of Ag Thin Films by Iodine Functionalization at Room Temperature: Evolution of Optoelectronic and Texture Properties

    PubMed Central

    Bashouti, Muhammad Y.; Talebi, Razieh; Kassar, Thaer; Nahal, Arashmid; Ristein, Jürgen; Unruh, Tobias; Christiansen, Silke H.

    2016-01-01

    We show a simple room temperature surface functionalization approach using iodine vapour to control a surface phase transition from cubic silver (Ag) of thin films into wurtzite silver-iodid (β-AgI) films. A combination of surface characterization techniques (optical, electronical and structural characterization) reveal distinct physical properties of the new surface phase. We discuss the AgI thin film formation dynamics and related transformation of physical properties by determining the work-function, dielectric constant and pyroelectric behavior together with morphological and structural thin film properties such as layer thickness, grain structure and texture formation. Notable results are: (i) a remarkable increase of the work-function (by 0.9 eV) of the Ag thin layer after short a iodine exposure time (≤60 s), with simultaneous increase of the thin film transparency (by two orders of magnitude), (ii) pinning of the Fermi level at the valance band maximum upon iodine functionalization, (iii) 84% of all crystallites grain were aligned as a result of the evolution of an internal electric field. Realizing a nano-scale layer stack composed of a dielectric AgI layer on top of a metallic thin Ag layer with such a simple method has some technological implications e.g. to realize optical elements such as planar optical waveguides. PMID:26899434

  18. Systematic Surface Phase Transition of Ag Thin Films by Iodine Functionalization at Room Temperature: Evolution of Optoelectronic and Texture Properties

    NASA Astrophysics Data System (ADS)

    Bashouti, Muhammad Y.; Talebi, Razieh; Kassar, Thaer; Nahal, Arashmid; Ristein, Jürgen; Unruh, Tobias; Christiansen, Silke H.

    2016-02-01

    We show a simple room temperature surface functionalization approach using iodine vapour to control a surface phase transition from cubic silver (Ag) of thin films into wurtzite silver-iodid (β-AgI) films. A combination of surface characterization techniques (optical, electronical and structural characterization) reveal distinct physical properties of the new surface phase. We discuss the AgI thin film formation dynamics and related transformation of physical properties by determining the work-function, dielectric constant and pyroelectric behavior together with morphological and structural thin film properties such as layer thickness, grain structure and texture formation. Notable results are: (i) a remarkable increase of the work-function (by 0.9 eV) of the Ag thin layer after short a iodine exposure time (≤60 s), with simultaneous increase of the thin film transparency (by two orders of magnitude), (ii) pinning of the Fermi level at the valance band maximum upon iodine functionalization, (iii) 84% of all crystallites grain were aligned as a result of the evolution of an internal electric field. Realizing a nano-scale layer stack composed of a dielectric AgI layer on top of a metallic thin Ag layer with such a simple method has some technological implications e.g. to realize optical elements such as planar optical waveguides.

  19. Chemically deposited In2S3-Ag2S layers to obtain AgInS2 thin films by thermal annealing

    NASA Astrophysics Data System (ADS)

    Lugo, S.; Peña, Y.; Calixto-Rodriguez, M.; López-Mata, C.; Ramón, M. L.; Gómez, I.; Acosta, A.

    2012-12-01

    AgInS2 thin films were obtained by the annealing of chemical bath deposited In2S3-Ag2S layers at 400 °C in N2 for 1 h. According to the XRD and EDX results the chalcopyrite structure of AgInS2 has been obtained. These films have an optical band gap, Eg, of 1.86 eV and an electrical conductivity value of 1.2 × 10-3 (Ω cm)-1.

  20. DESIGN OF A THIN QUADRUPOLE TO BE USED IN THE AGS SYNCHROTRON

    SciTech Connect

    TSOUPAS,N.; AHRENS, L.; ALFORQUE, R.; BAI, M.; BROWN, K.; COURANT, E.; ET AL.

    2007-06-25

    The Alternating Gradient Synchrotron (AGS) employs two partial helical snakes[l] to preserve the polarization of the proton beam during acceleration. In order to compensate for the focusing effect of the partial helical snakes on the beam optics in the AGS during acceleration of the beam, we introduced eight quadrupoles in straight sections of the AGS at the proximity of the partial snakes. At injection energies, the strength of each quad is set at a high value, and is ramped down to zero as the effect of the snakes diminishes by the square of beam's rigidity. Four of the eight compensation quadrupoles had to be placed in very short straight sections -30 cm in length, therefore the quadruples had be thin with an overall length of less than 30 cm. In this paper we will discus: (a) the mechanical and magnetic specifications of the ''thin'' quadrupole. (b) the method to minimize the strength of the dodecapole harmonic, (c) the method to optimize the thickness of the laminations that the magnet iron is made, (d) mechanical tolerances of the magnet, (e) comparison of the measured and calculated magnetic multipoles of the quadrupole.

  1. Electrical switching in sol-gel derived Ag -SiO2 nanocomposite thin films

    NASA Astrophysics Data System (ADS)

    Sarkar, D. K.; Cloutier, F.; El Khakani, M. A.

    2005-04-01

    The sol-gel technique has been used to produce Ag -SiO2 nanocomposite thin films consisting of silver nanoparticles embedded in a SiO2 matrix. The size of the silver nanoparticles is of about (4±0.2)nm when the firing temperature is in the (500-700°C ) range, as determined from ultraviolet-visible spectroscopy analysis. The increase of the firing temperature beyond 300°C, was found to lead to an outer diffusion of Ag toward the surface. As a consequence the surface atomic concentration of Ag is found to increase from 1.3% to 12% for the as-dried (at 120°C) and for those further fired at 600°C, respectively. On the other hand, it is shown that the electrical behavior of these Ag -SiO2 nanocomposite films can drastically change from highly insulating to conducting depending on the firing temperature used. In the intermediate firing temperature (300-400°C) range, the films were found to exhibit a reversible switching behavior with a resistivity transition of about 7 orders of magnitude between the insulating (OFF) and the conducting (ON) state. Such an electrical switching could be explained by a change in the predominant conduction mechanism of the films.

  2. Formation of nanodots and enhancement of thermoelectric power induced by ion irradiation in PbTe:Ag composite thin films

    NASA Astrophysics Data System (ADS)

    Bala, Manju; Meena, Ramcharan; Gupta, Srashti; Pannu, Compesh; Tripathi, Tripurari S.; Varma, Shikha; Tripathi, Surya K.; Asokan, K.; Avasthi, Devesh K.

    2016-07-01

    Present study demonstrates an enhancement in thermoelectric power of 10% Ag doped PbTe (PbTe:Ag) thin films when irradiated with 200 keV Ar ion. X-ray diffraction showed an increase in crystallinity for both PbTe and PbTe:10Ag nano-composite films after Ar ion irradiation due to annealing of defects in the grain boundaries. The preferential sputtering of Pb and Te ions in comparison to Ag ions resulted in the formation of nano-dots. This was further confirmed by X-ray photoelectron spectroscopy (XPS). Such an enhancement in thermoelectric power of irradiated PbTe:10Ag films in comparison to pristine PbTe:10Ag film is attributed to the decrease in charge carrier concentration that takes part in the transport process via restricting the tunneling of carriers through the wider potential barrier formed at the interface of nano-dots.

  3. SPR sensitivity of silver nanorods in CsBr-Ag nanocomposite thin films

    NASA Astrophysics Data System (ADS)

    Lovkush; Ravikant, Chhaya; Arun, P.; Kumar, Kuldeep

    2016-07-01

    We have investigated the optical and morphological properties of CsBr-Ag complex thin films deposited by thermal evaporation on glass substrate. By varying the thickness of the film with fixed mass ratio of cesium bromide and silver, we observed a broad absorption peak in the visible region from 350 to 450 nm corresponding to the transverse and longitudinal surface plasmon resonance (SPR) mode. Red shift is observed, with varying film thickness, in SPR peak position corresponding to longitudinal mode with no significant change in transverse mode due to variation in the aspect ratio of the silver nano crystalline grains. Scanning electron microscope and EDX revealed the formation of silver nanorods in film samples. Such, stable and tunable CsBr-Ag films can be used in optical filters.

  4. Optical and structural properties of Cr and Ag thin films deposited on glass substrate

    NASA Astrophysics Data System (ADS)

    Rauf, A.; Ahmed, K.; Nasim, F.; Khan, A. N.; Gul, A.

    2016-08-01

    Most of the rotating or noting patterns are being developed by using silver plating through chemical coating. Silver layers deteriorate with the passage of time and become less reflective while undergo through cleaning process due to its softness and the results become unpredictable. In this paper an alternate method for development of above mentioned pattern has been demonstrated. Chromium (Cr) and Silver (Ag) thin films of 200nm and 160nm thick respectively have been realized using electron beam evaporation (PVD technique) on quartz substrate. Structural analysis has been carried out by XRD and SEM while optical transmission/reflection has been studied using spectrophotometer. XRD analysis shows that Ag coated thin films exhibit FCC structure while Cr coated thin films reveals a BCC structure. SEM analysis shows almost smooth and uniform surfaces in both cases. After passing through high and low temperature cycles it was found that the results of pattern structures developed by chromium coating were more reliable than obtained through silver platting process.

  5. Quantum stabilities and growth modes of thin metal films: Unsupported and NiAl-supported Ag(1 1 0) and Ag(1 0 0)

    NASA Astrophysics Data System (ADS)

    Han, Yong; Evans, J. W.; Liu, Da-Jiang

    2008-07-01

    We present density functional theory (DFT) analyses of the stability of Ag thin films versus film thicknesses for various surface orientations. We include benchmark results for freestanding films, but consider in detail Ag(1 1 0) films supported on a NiAl(1 1 0) substrate, and Ag(1 0 0) films supported on a NiAl(1 0 0) substrate. The supported films exhibit an almost perfect lattice-match between film and substrate surface unit cells, so one can assess film stability in the absence of significant lateral mismatch strain. We also provide a characterization of film growth modes for these NiAl-supported Ag films based on DFT results for the relevant energetics.

  6. Surface electronic structure of polar NiO thin film grown on Ag(111)

    NASA Astrophysics Data System (ADS)

    Das, Jayanta; Menon, Krishnakumar S. R.

    2015-06-01

    The growth and structure of NiO thin films on top of Ag(111) substrate were studied where the formation of faceted surface was confirmed by Low Energy Electron Diffraction. The electronic structure of polar NiO(111) surface has been probed using photoemission techniques. The core energy levels and the valence band electronic structure were excited by x-ray and ultraviolet photons respectively. The modifications in physical structure and valence band electronic structure of the film under vacuum annealing have also been enlightened.

  7. Electrical and photoconductivity studies on AgSbSe2 thin films

    NASA Astrophysics Data System (ADS)

    Namitha Asokan, T.; Urmila, K. S.; Pradeep, B.

    2015-02-01

    Silver antimony selenide thin films have been deposited on ultrasonically cleaned glass substrate at a vacuum of 10-5 torr using reactive evaporation technique. The preparative parameters like substrate temperature and incident fluxes have been properly controlled in order to get highly reproducible compound films. The polycrystalline nature of the sample is confirmed using XRD. The dependence of the electrical conductivity on the temperature has also been studied. The prepared AgSbSe2 samples show p-type conductivity. The samples show a little photoresponse.

  8. Surface electronic structure of polar NiO thin film grown on Ag(111)

    SciTech Connect

    Das, Jayanta; Menon, Krishnakumar S. R.

    2015-06-24

    The growth and structure of NiO thin films on top of Ag(111) substrate were studied where the formation of faceted surface was confirmed by Low Energy Electron Diffraction. The electronic structure of polar NiO(111) surface has been probed using photoemission techniques. The core energy levels and the valence band electronic structure were excited by x-ray and ultraviolet photons respectively. The modifications in physical structure and valence band electronic structure of the film under vacuum annealing have also been enlightened.

  9. A dry method to synthesize dendritic Ag2Se nanostructures utilizing CdSe quantum dots and Ag thin films.

    PubMed

    Hu, Lian; Zhang, Bingpo; Xu, Tianning; Li, Ruifeng; Wu, Huizhen

    2015-01-01

    Dendritic Ag2Se nanostructures are synthesized in a dry environment by UV irradiating the hybrids composed of CdSe quantum dots (QDs) and silver (Ag). UV irradiation on CdSe QDs induces a photooxidation effect on the QD surface and leads to the formation of SeO2 components. Then SeO2 reacts with the Ag atoms in either Ag film or QD layer to produce the Ag2Se. The growth mechanism of Ag2Se dendrites on solid Ag films is explored and explained by a diffusion limited aggregation model in which the QD layer provides enough freedom for Ag2Se motion. Since the oxidation of the CdSe QDs is the critical step for the Ag2Se dendrites formation this dry chemical interaction between QDs and Ag film can be applied in the study of the QD surface chemical properties. With this dry synthesis method, the Ag2Se dendrites can also be facilely formed at the designed area on Ag substrates. PMID:25483981

  10. A dry method to synthesize dendritic Ag2Se nanostructures utilizing CdSe quantum dots and Ag thin films

    NASA Astrophysics Data System (ADS)

    Hu, Lian; Zhang, Bingpo; Xu, Tianning; Li, Ruifeng; Wu, Huizhen

    2015-01-01

    Dendritic Ag2Se nanostructures are synthesized in a dry environment by UV irradiating the hybrids composed of CdSe quantum dots (QDs) and silver (Ag). UV irradiation on CdSe QDs induces a photooxidation effect on the QD surface and leads to the formation of SeO2 components. Then SeO2 reacts with the Ag atoms in either Ag film or QD layer to produce the Ag2Se. The growth mechanism of Ag2Se dendrites on solid Ag films is explored and explained by a diffusion limited aggregation model in which the QD layer provides enough freedom for Ag2Se motion. Since the oxidation of the CdSe QDs is the critical step for the Ag2Se dendrites formation this dry chemical interaction between QDs and Ag film can be applied in the study of the QD surface chemical properties. With this dry synthesis method, the Ag2Se dendrites can also be facilely formed at the designed area on Ag substrates.

  11. The distribution of Ag in Ag-doped YBa2Cu3O7-δ thin film prepared by dual-beam pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    Zhou, W. Z.; Chua, D. H. C.; Xu, S. Y.; Ong, C. K.; Feng, Y. P.; Osipowicz, T.; Chen, M. S.

    1999-06-01

    The Ag distribution in Ag-doped YBa2Cu3O7-δ (YBCO) thin films fabricated by dual-beam pulsed-laser deposition on SrTiO3 (100) substrates has been studied by Auger electron spectroscopy, microproton-induced x-ray emission, atomic force microscopy and scanning electron microscopy. All the results consistently show that Ag aggregated in the bar-like structures observed in the film. These bars are aligned along the a-b-axis or at 45° to the a-b-axis of the YBCO thin film. The main body of the long bars aligned with the a-b-axes of the film was found to be a combination of metallic Ag with other precipitates of YBCO film that may grow from the substrate surface to the YBCO film surface. There were other precipitates aggregating as well at the surface of these bars, such as oxides of Cu and Ba. The short bars that aligned along 45° to the a-b-axes of the film were found to be deficient in Ag but rich in Cu, Ba and O, which could be oxide precipitates of YBCO. The growth mechanisms of the two types of bars seem quite different.

  12. Analysis of Ag sbnd Co thin film alloys using PIXE and RBS

    NASA Astrophysics Data System (ADS)

    Sˇandrik, R.; Grime, G. W.

    1996-04-01

    The Ag sbnd Co system representing a grain type alloy has non-mixing properties resulting in the formation of pure metal precipitates under certain conditions. 50 nm thin layers of Ag 1- xCo x (0.35≤x≤0.55) on SiO 2Si substrates were analysed using microbeam PIXE and RBS to determine whether structural changes following 600°C annealing could be detected. With the aim to estimate the accuracy of proposed analytical techniques the parameters of linear model CiPIXE= f( CiRBS) have been statistically tested. Using a 1 μm beam of 2 MeV protons many random point analyses were carried out on areas ranging from 20 × 20 μm 2 to 2000 ×2000 μm 2. Statistical evaluation of this data shows differences in the Ag/Co yields ratio for annealed as well as non-annealed samples. Lateral concentration inhomogeneity on a scale less than the beam diameter can be observed within a sample according to the analysis of variance based on an F-test of many random point analyses.

  13. Synthesis and Characterization of Varying Concentrations of Ag-doped ZnO Thin Films

    NASA Astrophysics Data System (ADS)

    Hachlica, Justin; Wadie-Ibrahim, Patrick; Sahiner, M. Alper

    Silver doped ZnO is a promising compound for photovoltaic solar cell use. Doping this compound with varying amounts of silver will theoretically make this type of thin film more efficient by reducing the overall resistance and increasing the voltage and current output. The extent of this promise is being tested experimentally, by analysis of both the electrical and the surface roughness properties of the cells. Ag-doped Zinc Oxide is deposited by method of Pulsed Laser Deposition (PLD) onto Indium Tin Oxide (ITO) coated Glass. Annealing effects were also observed by varying the temperature at which the annealing occurred after synthesis of the sample. Thickness is confirmed by use of Ellipsometery. X-Ray Diffraction (XRD) measurements confirmed a ZnO crystal structure on the thin films. The active dopant carrier concentrations were determined using a Hall Effect Measuring System. Finally, the photovoltaic properties of the film are recorded by using a Keithley Source Meter. The structural characterization and electrical results of the effect of Ag doping on ZnO will then be discussed.

  14. Thermal tuning of surface plasmon resonance: Ag gratings on barium strontium titanate thin films

    NASA Astrophysics Data System (ADS)

    Xin, J. Z.; Hui, K. C.; Wang, K.; Chan, H. L. W.; Ong, D. H. C.; Leung, C. W.

    2012-04-01

    Surface plasmon tuning via thermally induced refractive index changes in ferroelectrics is investigated. Epitaxial (Ba0.7Sr0.3)TiO3 (BST) thin films were deposited on MgO (001) substrates by pulsed laser deposition. The refractive index of BST thin films measured by the prism-coupling technique was found to increase from 2.3932 (TE)/1.9945 (TM) at room temperature to 2.3949 (TE)/1.9965 (TM) at 66°C. Then 30-nm-Ag gratings with periodicity 750 nm and width 300 nm were fabricated on BST by soft ultraviolet nanoimprint lithography and subsequent lift-off process. The reflection spectra from 500 to 1000 nm with incident angle from 5° to 60° were measured at room temperature and 66°C, with a collimated and p-polarized light incident perpendicularly to the grating direction. Several modes were observed from the spectra. At 66°C, a red shift of a dip at about 850 nm by 2 nm was obtained at an incident angle of 15°. Calculations confirmed that the observed modes belong to the (-1), (2), (-2) and (3) surface plasmon modes from the Ag and BST interfaces and localized mode; the red shift by thermal tuning is also confirmed. The results indicate the feasibility of active modulation in surface plasmon resonance in solid-state structures.

  15. Characterization of Ag nanostructures fabricated by laser-induced dewetting of thin films

    NASA Astrophysics Data System (ADS)

    Nikov, Ru. G.; Nedyalkov, N. N.; Atanasov, P. A.; Hirsch, D.; Rauschenbach, B.; Grochowska, K.; Sliwinski, G.

    2016-06-01

    The paper presents results on laser nanostructuring of Ag thin films. The thin films are deposited on glass substrates by pulsed laser deposition technology. The as fabricated films are then annealed by nanosecond laser pulses delivered by Nd:YAG laser system operated at λ = 355 nm. The film modification is studied as a function of the film thickness and the parameters of the laser irradiation as pulse number and laser fluence. In order to estimate the influence of the environment on the characteristics of the fabricated structures the Ag films are annealed in different surrounding media: water, air and vacuum. It is found that at certain conditions the laser treatment may lead to decomposition of the films into a monolayer of nanoparticles with narrow size distribution. The optical properties of the fabricated nanostructures are investigated on the basis of transmission spectra taken by optical spectrometer. In the measured spectra plasmon resonance band is observed as its shape and position vary depending on the processing conditions. The fabricated structures are covered with Rhodamine 6G and tested as active substrates for Surface Enhanced Raman Spectroscopy (SERS).

  16. Laser irradiation of ZnO:Al/Ag/ZnO:Al multilayers for electrical isolation in thin film photovoltaics

    NASA Astrophysics Data System (ADS)

    Crupi, Isodiana; Boscarino, Stefano; Torrisi, Giacomo; Scapellato, Giorgia; Mirabella, Salvatore; Piccitto, Giovanni; Simone, Francesca; Terrasi, Antonio

    2013-09-01

    Laser irradiation of ZnO:Al/Ag/ZnO:Al transparent contacts is investigated for segmentation purposes. The quality of the irradiated areas has been experimentally evaluated by separation resistance measurements, and the results are complemented with a thermal model used for numerical simulations of the laser process. The presence of the Ag interlayer plays two key effects on the laser scribing process by increasing the maximum temperature reached in the structure and accelerating the cool down process. These evidences can promote the use of ultra-thin ZnO:Al/Ag/ZnO:Al electrode in large-area products, such as for solar modules.

  17. Laser irradiation of ZnO:Al/Ag/ZnO:Al multilayers for electrical isolation in thin film photovoltaics

    PubMed Central

    2013-01-01

    Laser irradiation of ZnO:Al/Ag/ZnO:Al transparent contacts is investigated for segmentation purposes. The quality of the irradiated areas has been experimentally evaluated by separation resistance measurements, and the results are complemented with a thermal model used for numerical simulations of the laser process. The presence of the Ag interlayer plays two key effects on the laser scribing process by increasing the maximum temperature reached in the structure and accelerating the cool down process. These evidences can promote the use of ultra-thin ZnO:Al/Ag/ZnO:Al electrode in large-area products, such as for solar modules. PMID:24053228

  18. Large-scale preparation of strawberry-like, AgNP-doped SiO2 microspheres using the electrospraying method

    NASA Astrophysics Data System (ADS)

    Ma, Zhijun; Ji, Huijiao; Tan, Dezhi; Dong, Guoping; Teng, Yu; Zhou, Jiajia; Guan, Miaojia; Qiu, Jianrong; Zhang, Ming

    2011-07-01

    In this paper, we report on a novel strategy for the preparation of silver nanoparticle-doped SiO2 microspheres (Ag-SMSs) with an interesting strawberry-like morphology using a simple and efficient electrospraying method. SEM (scanning electron microscopy), TEM (transmission electron microscopy), XRD (x-ray diffraction), EDS (energy-dispersive spectroscopy) and UV-vis spectra (ultraviolet-visible spectra) were applied to investigate the morphology, structure, composition and optical properties of the hybrid microspheres, and E. coli (Escherichia coli) was used as a model microbe to evaluate their antibacterial ability. The results showed that the Ag-SMSs were environmentally stable and washing resistant. The Ag-SMSs exhibited effective inhibition against proliferation of E. coli, and their antibacterial ability could be well preserved for a long time. The environmental stability, washing resistance, efficient antibacterial ability and simple but productive preparation method endowed the Ag-SMSs with great potential for practical biomedical applications.

  19. Application of patterned Ag-nanowire networks to transparent thin-film heaters and electrodes for organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Kim, Seung-Rok; Triambulo, Ross E.; Kim, Jin-Hoon; Park, Jaeyoon; Jeong, Unyong; Park, Jin-Woo

    2016-06-01

    We present patterned Ag-nanowire (AgNW) networks for their application to transparent electrodes in flexible devices. Using capillary-force-based soft lithography (CFL), we formed 25- to 30-µm-wide line patterns of AgNWs on flexible polymer substrates. Organic light-emitting diodes (OLEDs) and transparent thin-film heaters (TFHs) were successfully fabricated on the patterned substrates, which verified the potential of AgNW patterns formed by CFL as interconnects in flexible devices.

  20. Stable and efficient multi-crystalline n+p silicon photocathode for H2 production with pyramid-like surface nanostructure and thin Al2O3 protective layer

    NASA Astrophysics Data System (ADS)

    Fan, Ronglei; Dong, Wen; Fang, Liang; Zheng, Fengang; Su, Xiaodong; Zou, Shuai; Huang, Jie; Wang, Xusheng; Shen, Mingrong

    2015-01-01

    When a Si photocathode is used in a photoelectrochemical cell for H2 production, an open nanostructure capable of enhanced light absorption, low surface recombination, and being fully protected by thin protective layer is highly desirable. Here, we explored a highly stable and efficient multi-crystalline (mc) n+p silicon photocathode. A pyramid-like surface nanostructure on mc-Si wafer was fulfilled through a two-step metal-catalyzed chemical etching process, and then a n+p junction photocathode protected by a thin Al2O3 layer was constructed. The photocathode exhibits a high stability of continuous photoelectrochemical H2 production for above 100 h after a thin layer of Al2O3 is coated on its surface, and its energy conversion efficiency can be up to 6.8% after Pt loading, due to the lowered surface light reflection, increased surface area and minority carrier life time on the electrode surface.

  1. Co-assembled thin films of Ag nanowires and functional nanoparticles at the liquid-liquid interface by shaking

    NASA Astrophysics Data System (ADS)

    Zhang, Shao-Yi; Liu, Jian-Wei; Zhang, Chuan-Ling; Yu, Shu-Hong

    2013-05-01

    In this paper, we report the fabrication of co-assembled thin films composed of silver nanowires (NWs) and Au nanoparticles (NPs) at the liquid-liquid interface (water-chloroform) by vigorous shaking. The composition of co-assembled thin films can be controlled by adjusting the concentration of the nanosized building blocks. As a versatile interfacial assembly method, other nanoparticles such as Ag2S and Fe3O4 NPs can also be co-assembled with Ag NWs using the same procedure. Meanwhile, the co-assembly state of the obtained Au NPs and Ag NWs makes a significant contribution to the high sensitivity of surface-enhanced Raman scattering (SERS) to model the molecule 3,3'-diethylthiatricarbocyanine iodide (DTTCI). The SERS intensities show high dependence on the molar ratio of Au NPs and Ag NWs and the layer number of the co-assembled thin films. This shaking-assisted liquid-liquid assembly system has been proved to be a facile way for co-assembling nanowires and nanoparticles, and will pave a way for further applications of the macroscopic co-assemblies with novel functionalities.In this paper, we report the fabrication of co-assembled thin films composed of silver nanowires (NWs) and Au nanoparticles (NPs) at the liquid-liquid interface (water-chloroform) by vigorous shaking. The composition of co-assembled thin films can be controlled by adjusting the concentration of the nanosized building blocks. As a versatile interfacial assembly method, other nanoparticles such as Ag2S and Fe3O4 NPs can also be co-assembled with Ag NWs using the same procedure. Meanwhile, the co-assembly state of the obtained Au NPs and Ag NWs makes a significant contribution to the high sensitivity of surface-enhanced Raman scattering (SERS) to model the molecule 3,3'-diethylthiatricarbocyanine iodide (DTTCI). The SERS intensities show high dependence on the molar ratio of Au NPs and Ag NWs and the layer number of the co-assembled thin films. This shaking-assisted liquid-liquid assembly system

  2. Collective magnetic behaviors of Fe-Ag nanostructured thin films above the percolation limit

    SciTech Connect

    Alonso, J.; Fdez-Gubieda, M. L.; Barandiaran, J. M.; Svalov, A.; Sarmiento, G.; Fernandez Barquin, L.; Pedro, I. de; Orue, I.

    2009-04-01

    The magnetic behavior of sputtered and pulsed laser deposited (PLD) Fe{sub x}Ag{sub 100-x} thin films with 27{<=}x{<=}55 has been studied by means of ac and dc magnetic measurements. Sputtered samples present a continuous decrease in the magnetization, down to 310 K for x=30, where a magnetic transition into a superparamagnetic state with the presence of dipolar interactions is observed. The ac susceptibility measurements indicate that this transition resembles that of three dimensional glassy systems. Sputtered samples with higher concentration of Fe present a similar but slower thermal evolution of magnetization. PLD samples with x{>=}50 show a Curie-Weiss-type transition above {approx}200 K triggered by direct exchange interactions. As the temperature decreases, the system behaves like a ferromagnet and below {approx}75 K, a transition into a cluster-glass state appears. As the composition decreases, these phenomena vanish.

  3. Silver activation on thin films of Ag-ZrCN coatings for antimicrobial activity.

    PubMed

    Ferreri, I; Calderon V, S; Escobar Galindo, R; Palacio, C; Henriques, M; Piedade, A P; Carvalho, S

    2015-10-01

    Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr+Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5% (w/v) NaClO solution for 5 min. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11 at.% of Ag. The morphology analysis of the surface before and after the activation procedure revealed differences in silver distribution indicating segregation/diffusion of the metallic element to the film's surface. Thus, the results indicate that the silver activation step is responsible for an antimicrobial effect of the coatings, due to silver oxidation and silver ion release.

  4. Silver activation on thin films of Ag-ZrCN coatings for antimicrobial activity.

    PubMed

    Ferreri, I; Calderon V, S; Escobar Galindo, R; Palacio, C; Henriques, M; Piedade, A P; Carvalho, S

    2015-10-01

    Nowadays, with the increase of elderly population and related health problems, knee and hip joint prosthesis are being widely used worldwide. However, failure of these invasive devices occurs in a high percentage thus demanding the revision of the chirurgical procedure. Within the reasons of failure, microbial infections, either hospital or subsequently-acquired, contribute in high number to the statistics. Staphylococcus epidermidis (S. epidermidis) has emerged as one of the major nosocomial pathogens associated with these infections. Silver has a historic performance in medicine due to its potent antimicrobial activity, with a broad-spectrum on the activity of different types of microorganisms. Consequently, the main goal of this work was to produce Ag-ZrCN coatings with antimicrobial activity, for the surface modification of hip prostheses. Thin films of ZrCN with several silver concentrations were deposited onto stainless steel 316 L, by DC reactive magnetron sputtering, using two targets, Zr and Zr with silver pellets (Zr+Ag target), in an atmosphere containing Ar, C2H2 and N2. The antimicrobial activity of the modified surfaces was tested against S. epidermidis and the influence of an activation step of silver was assessed by testing samples after immersion in a 5% (w/v) NaClO solution for 5 min. The activation procedure revealed to be essential for the antimicrobial activity, as observed by the presence of an inhibition halo on the surface with 11 at.% of Ag. The morphology analysis of the surface before and after the activation procedure revealed differences in silver distribution indicating segregation/diffusion of the metallic element to the film's surface. Thus, the results indicate that the silver activation step is responsible for an antimicrobial effect of the coatings, due to silver oxidation and silver ion release. PMID:26117788

  5. Ag2ZnSn(S,Se)4: A highly promising absorber for thin film photovoltaics.

    PubMed

    Chagarov, Evgueni; Sardashti, Kasra; Kummel, Andrew C; Lee, Yun Seog; Haight, Richard; Gershon, Talia S

    2016-03-14

    The growth in efficiency of earth-abundant kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells has slowed, due in part to the intrinsic limitations imposed by the band tailing attributed primarily to I-II antisite exchange. In this study, density functional theory simulations show that when Ag is substituted for Cu to form kesterite Ag2ZnSnSe4 (AZTSe), the I-II isolated antisite formation energy becomes 3.7 times greater than in CZTSSe, resulting in at least an order of magnitude reduction in I-II antisite density. Experimental evidence of an optoelectronically improved material is also provided. Comparison of the low-temperature photoluminescence (PL) structure of Cu(In,Ga)Se2 (CIGSe), CZTSSe, and AZTSe shows that AZTSe has a shallow defect structure with emission significantly closer to the band edge than CZTSe. Existence of suppressed band tailing is found in the proximity of the room-temperature PL peak of AZTSe to its measured band gap. The results are consistent with AZTSe being a promising alternative to CZTSSe and CIGSe for thin film photovoltaics.

  6. Ag2ZnSn(S,Se)4: A highly promising absorber for thin film photovoltaics.

    PubMed

    Chagarov, Evgueni; Sardashti, Kasra; Kummel, Andrew C; Lee, Yun Seog; Haight, Richard; Gershon, Talia S

    2016-03-14

    The growth in efficiency of earth-abundant kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells has slowed, due in part to the intrinsic limitations imposed by the band tailing attributed primarily to I-II antisite exchange. In this study, density functional theory simulations show that when Ag is substituted for Cu to form kesterite Ag2ZnSnSe4 (AZTSe), the I-II isolated antisite formation energy becomes 3.7 times greater than in CZTSSe, resulting in at least an order of magnitude reduction in I-II antisite density. Experimental evidence of an optoelectronically improved material is also provided. Comparison of the low-temperature photoluminescence (PL) structure of Cu(In,Ga)Se2 (CIGSe), CZTSSe, and AZTSe shows that AZTSe has a shallow defect structure with emission significantly closer to the band edge than CZTSe. Existence of suppressed band tailing is found in the proximity of the room-temperature PL peak of AZTSe to its measured band gap. The results are consistent with AZTSe being a promising alternative to CZTSSe and CIGSe for thin film photovoltaics. PMID:26979701

  7. Ag2ZnSn(S,Se)4: A highly promising absorber for thin film photovoltaics

    NASA Astrophysics Data System (ADS)

    Chagarov, Evgueni; Sardashti, Kasra; Kummel, Andrew C.; Lee, Yun Seog; Haight, Richard; Gershon, Talia S.

    2016-03-01

    The growth in efficiency of earth-abundant kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells has slowed, due in part to the intrinsic limitations imposed by the band tailing attributed primarily to I-II antisite exchange. In this study, density functional theory simulations show that when Ag is substituted for Cu to form kesterite Ag2ZnSnSe4 (AZTSe), the I-II isolated antisite formation energy becomes 3.7 times greater than in CZTSSe, resulting in at least an order of magnitude reduction in I-II antisite density. Experimental evidence of an optoelectronically improved material is also provided. Comparison of the low-temperature photoluminescence (PL) structure of Cu(In,Ga)Se2 (CIGSe), CZTSSe, and AZTSe shows that AZTSe has a shallow defect structure with emission significantly closer to the band edge than CZTSe. Existence of suppressed band tailing is found in the proximity of the room-temperature PL peak of AZTSe to its measured band gap. The results are consistent with AZTSe being a promising alternative to CZTSSe and CIGSe for thin film photovoltaics.

  8. Dynamic fatigue behaviour of Ag-doped Bi-2212 textured thin rods

    NASA Astrophysics Data System (ADS)

    Madre, M. A.; Rasekh, Sh; Diez, J. C.; Sotelo, A.

    2009-03-01

    The flexural strength of 1 wt.% Ag-doped Bi2Sr2CaCu2O8+δ thin rods textured by a laser heated floating zone was measured as a function of the environmental conditions (air versus water) at room temperature. Loading rates spanning three orders of magnitude (1, 10 and 100 μm/min) were used to explore their susceptibility to the environmental conditions. These mechanical tests were completed with electrical characterization (critical current at 77K and resistivity from 77 to 300 K) of samples submerged in distilled water for different time lengths (0, 12 and 120h). While Bi2Sr2CaCu2O8+δ has been shown, in previous works, to be unstable during contact with water molecules, the Ag-doped Bi-2212 textured rods tested in this work are very inert to the water environment, with respect to their mechanical and electrical properties, due to the presence of a narrow (approx150 μm) low textured outer ring formed in the growth process.

  9. Development of Ag/WO3/ITO thin film memristor using spray pyrolysis method

    NASA Astrophysics Data System (ADS)

    Dongale, T. D.; Mohite, S. V.; Bagade, A. A.; Gaikwad, P. K.; Patil, P. S.; Kamat, R. K.; Rajpure, K. Y.

    2015-11-01

    The unique nonlinear relationship between charge and magnetic flux along with the pinched hysteresis loop in I- V plane provide memory with resistance combinations of attribute to Memristor which lead to their novel applications in non volatile memory, nonlinear dynamics, analog computations and neuromorphic biological systems etc. The present paper reports development of Ag/WO3/ITO thin film memristor device using spray pyrolysis method. The structural, morphological and electrical properties of the thin film memristor device are further characterized using x-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and semiconductor device analyzer. The memristor is simulated using linear dopent drift model to ascertain the theoretical and experimental conformations. For the simulation purpose, the width of doped region (w) limited to the interval [0, D] is considered as a state variable along with the window function characterized by the equation f ( x) = w (1 - w). The reported memristor device exhibits the symmetric pinched hysteresis loop in I- V plane within the low operating voltage (±1 V). [Figure not available: see fulltext.

  10. Scanning tunneling microscopy/spectroscopy of picene thin films formed on Ag(111)

    SciTech Connect

    Yoshida, Yasuo Yokosuka, Takuya; Hasegawa, Yukio; Yang, Hung-Hsiang; Huang, Hsu-Sheng; Guan, Shu-You; Su, Wei-Bin; Chang, Chia-Seng; Yanagisawa, Susumu; Lin, Minn-Tsong; Hoffmann, Germar

    2014-09-21

    Using ultrahigh-vacuum low-temperature scanning tunneling microscopy and spectroscopy combined with first principles density functional theory calculations, we have investigated structural and electronic properties of pristine and potassium (K)-deposited picene thin films formed in situ on a Ag(111) substrate. At low coverages, the molecules are uniformly distributed with the long axis aligned along the [112{sup ¯}] direction of the substrate. At higher coverages, ordered structures composed of monolayer molecules are observed, one of which is a monolayer with tilted and flat-lying molecules resembling a (11{sup ¯}0) plane of the bulk crystalline picene. Between the molecules and the substrate, the van der Waals interaction is dominant with negligible hybridization between their electronic states; a conclusion that contrasts with the chemisorption exhibited by pentacene molecules on the same substrate. We also observed a monolayer picene thin film in which all molecules were standing to form an intermolecular π stacking. Two-dimensional delocalized electronic states are found on the K-deposited π stacking structure.

  11. Scanning tunneling microscopy/spectroscopy of picene thin films formed on Ag(111).

    PubMed

    Yoshida, Yasuo; Yang, Hung-Hsiang; Huang, Hsu-Sheng; Guan, Shu-You; Yanagisawa, Susumu; Yokosuka, Takuya; Lin, Minn-Tsong; Su, Wei-Bin; Chang, Chia-Seng; Hoffmann, Germar; Hasegawa, Yukio

    2014-09-21

    Using ultrahigh-vacuum low-temperature scanning tunneling microscopy and spectroscopy combined with first principles density functional theory calculations, we have investigated structural and electronic properties of pristine and potassium (K)-deposited picene thin films formed in situ on a Ag(111) substrate. At low coverages, the molecules are uniformly distributed with the long axis aligned along the [112̄] direction of the substrate. At higher coverages, ordered structures composed of monolayer molecules are observed, one of which is a monolayer with tilted and flat-lying molecules resembling a (11̄0) plane of the bulk crystalline picene. Between the molecules and the substrate, the van der Waals interaction is dominant with negligible hybridization between their electronic states; a conclusion that contrasts with the chemisorption exhibited by pentacene molecules on the same substrate. We also observed a monolayer picene thin film in which all molecules were standing to form an intermolecular π stacking. Two-dimensional delocalized electronic states are found on the K-deposited π stacking structure. PMID:25240362

  12. Study of Ag transport in Cr2N0.61-7Ag nanocomposite thin film due to thermal exposition

    NASA Astrophysics Data System (ADS)

    Bílek, P.; Jurči, P.; Podgornik, B.; Jenko, D.; Hudáková, M.; Kusý, M.

    2015-12-01

    Cr2N0.61-7Ag nanocomposite coatings were deposited on substrates made of Cr-V ledeburitic tool steel Vanadis 6 using reactive magnetron sputtering at a deposition temperature of 500 °C. Investigations of as-deposited films and annealing experiments in closed-air atmosphere at temperatures of 300, 400 and 500 °C and the durations up to 24 h, followed by quantitative scanning electron microscopy, transmission electron microscopy, Auger electron spectroscopy and X-ray diffraction revealed that the films were composed of Cr2N0.61 matrix and individual silver agglomerates located along columnar crystals of the matrix. The maximal size of Ag-agglomerates was 80 nm. The surface population density of silver agglomerates increased with prolonging the annealing time up to 2 h and then decreased. The increase was more pronounced at lower annealing temperatures. This behaviour was referred to the competition between three phenomena, namely the transport of detached Ag atoms to the free surface, formation of oxide layer on the surface and sublimation of silver from the surface. At lower temperatures and/or shorter annealing times, the Ag-transport to the free surface was determined to be prevalent, thus, an increase in population density of silver agglomerates was determined. On the other hand, for higher temperatures and/or longer annealing times the population density of Ag-agglomerates rather decreased due to retarding effect of thicker oxide layer and sublimation of silver.

  13. Structural and optical properties of (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin film alloys

    SciTech Connect

    Boyle, J. H.; Shafarman, W. N.; Birkmire, R. W.; McCandless, B. E.

    2014-06-14

    The structural and optical properties of pentenary alloy (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin films were characterized over the entire compositional range at a fixed (Cu + Ag)/(In + Ga) ratio. Films deposited at 550 °C on bare and molybdenum coated soda-lime glass by elemental co-evaporation in a single-stage process with constant incident fluxes exhibit single phase chalcopyrite structure, corresponding to 122 spacegroup (I-42d) over the entire compositional space. Unit cell refinement of the diffraction patterns show that increasing Ag substitution for Cu, the refined a{sub o} lattice constant, (Ag,Cu)-Se bond length, and anion displacement increase in accordance with the theoretical model proposed by Jaffe, Wei, and Zunger. However, the refined c{sub o} lattice constant and (In,Ga)-Se bond length deviated from theoretical expectations for films with mid-range Ag and Ga compositions and are attributed to influences from crystallographic bond chain ordering or cation electronegativity. The optical band gap, derived from transmission and reflection measurements, widened with increasing Ag and Ga content, due to influences from anion displacement and cation electronegativity, as expected from theoretical considerations for pseudo-binary chalcopyrite compounds.

  14. Optical absorption characteristics of polycrystalline AgGaSe2 thin films

    NASA Astrophysics Data System (ADS)

    Bhuiyan, M. R. A.; Firoz Hasan, S. M.

    2006-12-01

    Silver gallium di-selenide (AgGaSe2) composite thin films have been formed onto ultrasonically and chemically cleaned glass substrates by in situ thermal annealing of the stack of successively evaporated individual elemental layers in vacuum. The structural properties of the films were ascertained by the x-ray diffraction method. The diffractogram indicated that these films were polycrystalline in nature having tetragonal structure with lattice parameters, a ap 6.00 Å and c ap 10.92 Å and average grain dimension 40 nm. The optical properties and atomic compositions of the films have been determined by UV-VIS-NIR spectrophotometry (photon wavelength ranging between 300 and 2500 nm) and energy dispersive analysis of x-ray, respectively. The typical optical absorption characteristic of the films has been critically analysed. The optical absorption coefficients vary from 103 to 105 cm-1 in the measured wavelength range of photons. The films have more than one type of fundamental electronic transitions. Direct allowed and direct forbidden transitions vary from 1.628 to 1.748 eV and 2.077 to 2.193 eV, respectively, depending on the composition of the films. The former transitions are found to have a general tendency to be symmetric around non-molecularity ΔX = 0, defined by ΔX = [(Ag/Ga)] - 1, while the latter shows no such dependence. Stoichiometric or slightly silver-deficient films show electron transition energies closer to the single crystal value. Spin-orbit splitting of the valence band becomes minimum at perfect stoichiometry.

  15. A Solid-State Thin-Film Ag/AgCl Reference Electrode Coated with Graphene Oxide and Its Use in a pH Sensor

    PubMed Central

    Kim, Tae Yong; Hong, Sung A; Yang, Sung

    2015-01-01

    In this study, we describe a novel solid-state thin-film Ag/AgCl reference electrode (SSRE) that was coated with a protective layer of graphene oxide (GO). This layer was prepared by drop casting a solution of GO on the Ag/AgCl thin film. The potential differences exhibited by the SSRE were less than 2 mV for 26 days. The cyclic voltammograms of the SSRE were almost similar to those of a commercial reference electrode, while the diffusion coefficient of Fe(CN)63− as calculated from the cathodic peaks of the SSRE was 6.48 × 10−6 cm2/s. The SSRE was used in conjunction with a laboratory-made working electrode to determine its suitability for practical use. The average pH sensitivity of this combined sensor was 58.5 mV/pH in the acid-to-base direction; the correlation coefficient was greater than 0.99. In addition, an integrated pH sensor that included the SSRE was packaged in a secure digital (SD) card and tested. The average sensitivity of the chip was 56.8 mV/pH, with the correlation coefficient being greater than 0.99. In addition, a pH sensing test was also performed by using a laboratory-made potentiometer, which showed a sensitivity of 55.4 mV/pH, with the correlation coefficient being greater than 0.99. PMID:25789490

  16. Surface resistance and residual losses of Ag-doped YBa2Cu3O7 - delta thin films on sapphire

    NASA Astrophysics Data System (ADS)

    Pinto, R.; Apte, P. R.; Hegde, M. S.; Kumar, Dhananjay

    1995-04-01

    High-quality Ag-doped YBa2Cu3O7-δ thin films have been grown by laser ablation on R-plane <11¯02> sapphire without any buffer layer. Thin films have been found to be highly c-axis oriented with Tc=90 K, transition width ΔT≤1 K, and transport Jc=1.2×106 A cm-2 at 77 K in self-field conditions. The microwave surface resistance of these films measured on patterned microstrip resonators has been found to be 530 μΩ at 10 GHz at 77 K which is the lowest reported on unbuffered sapphire. Improved in-plane epitaxy and reduced reaction rate between the substrate and the film caused due to Ag in the film are believed to be responsible for this greatly improved microwave surface resistance.

  17. Microwave sintering of Ag-nanoparticle thin films on a polyimide substrate

    SciTech Connect

    Fujii, S.; Kawamura, S.; Maitani, M. M.; Suzuki, E.; Wada, Y.; Mochizuki, D.

    2015-12-15

    Ag-nanoparticle thin films on a polyimide substrate were subjected to microwave sintering by use of a single-mode waveguide applicator. A two-step sintering process was employed. First, at low conductivities of the film, the film sample was placed at the site of the maximum electric field and subjected to microwave irradiation. Second, when the conductivity of the film increased, the film sample was placed at the site of the maximum magnetic field and again subjected to microwave irradiation. The microwave sintering process was completed within 1.5 min, which is significantly lower than the time required for the oven heating process. The resulting conductivity of the film, albeit only 30% of that of the bulk material, was seven times that of a film annealed at the same temperature in a furnace. Scanning electron microscopy images revealed that the nanoparticles underwent both grain necking and grain growth during microwave sintering. In addition, this sintering process was equivalent to the oven heating process performed at a 50 °C higher annealing temperature. An electromagnetic wave simulation and a heat transfer simulation of the microwave sintering process were performed to gain a thorough understanding of the process.

  18. Determination of the compositions of the DIGM zone in nanocrystalline Ag/Au and Ag/Pd thin films by secondary neutral mass spectrometry

    PubMed Central

    Molnár, Gábor Y; Shenouda, Shenouda S; Katona, Gábor L; Langer, Gábor A

    2016-01-01

    Summary Alloying by grain boundary diffusion-induced grain boundary migration is investigated by secondary neutral mass spectrometry depth profiling in Ag/Au and Ag/Pd nanocrystalline thin film systems. It is shown that the compositions in zones left behind the moving boundaries can be determined by this technique if the process takes place at low temperatures where solely the grain boundary transport is the contributing mechanism and the gain size is less than the half of the grain boundary migration distance. The results in Ag/Au system are in good accordance with the predictions given by the step mechanism of grain boundary migration, i.e., the saturation compositions are higher in the slower component (i.e., in Au or Pd). It is shown that the homogenization process stops after reaching the saturation values and further intermixing can take place only if fresh samples with initial compositions, according to the saturation values, are produced and heat treated at the same temperature. The reversal of the film sequence resulted in the reversal of the inequality of the compositions in the alloyed zones, which is in contrast to the above theoretical model, and explained by possible effects of the stress gradients developed by the diffusion processes itself. PMID:27335738

  19. Determination of the compositions of the DIGM zone in nanocrystalline Ag/Au and Ag/Pd thin films by secondary neutral mass spectrometry.

    PubMed

    Molnár, Gábor Y; Shenouda, Shenouda S; Katona, Gábor L; Langer, Gábor A; Beke, Dezső L

    2016-01-01

    Alloying by grain boundary diffusion-induced grain boundary migration is investigated by secondary neutral mass spectrometry depth profiling in Ag/Au and Ag/Pd nanocrystalline thin film systems. It is shown that the compositions in zones left behind the moving boundaries can be determined by this technique if the process takes place at low temperatures where solely the grain boundary transport is the contributing mechanism and the gain size is less than the half of the grain boundary migration distance. The results in Ag/Au system are in good accordance with the predictions given by the step mechanism of grain boundary migration, i.e., the saturation compositions are higher in the slower component (i.e., in Au or Pd). It is shown that the homogenization process stops after reaching the saturation values and further intermixing can take place only if fresh samples with initial compositions, according to the saturation values, are produced and heat treated at the same temperature. The reversal of the film sequence resulted in the reversal of the inequality of the compositions in the alloyed zones, which is in contrast to the above theoretical model, and explained by possible effects of the stress gradients developed by the diffusion processes itself. PMID:27335738

  20. A chemical bath deposition route to facet-controlled Ag3PO4 thin films with improved visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Gunjakar, Jayavant L.; Jo, Yun Kyung; Kim, In Young; Lee, Jang Mee; Patil, Sharad B.; Pyun, Jae.-Chul.; Hwang, Seong-Ju

    2016-08-01

    A facile, economic, and reproducible chemical bath deposition (CBD) method is developed for the fabrication of facet-controlled Ag3PO4 thin films with enhanced visible light photocatalytic activity. The fine-control of bath temperature, precursor, complexing agent, substrate, and solution pH is fairly crucial in preparing the facet-selective thin film of Ag3PO4 nanocrystal. The change of precursor from silver nitrate to silver acetate makes possible the tailoring of the crystal shape of Ag3PO4 from cube to rhombic dodecahedron and also the bandgap tuning of the deposited films. The control of [Ag+]/[phosphate] ratio enables to maximize the loading amount of Ag3PO4 crystals per the unit area of the deposited film. All the fabricated Ag3PO4 thin films show high photocatalytic activity for visible light-induced degradation of organic molecules, which can be optimized by tailoring the crystal shape of the deposited crystals. This CBD method is also useful in preparing the facet-controlled hybrid film of Ag3PO4-ZnO photocatalyst. The present study clearly demonstrates the usefulness of the present CBD method for fabricating facet-controlled thin films of metal oxosalt and its nanohybrid.

  1. Effect of mesh patterning with UV pulsed-laser on optical and electrical properties of ZnO/Ag-Ti thin films

    NASA Astrophysics Data System (ADS)

    Kao, K. S.; Cheng, D. L.; Chang, S. H.; Hsieh, P. T.; Chin, H. S.; Lin, H. K.

    2010-10-01

    In this study, the ZnO/Ag-Ti structure for transparence conducting oxide (TCO) is investigated by optimizing the thickness of the Ag-Ti alloy and ZnO layers. The Ag-Ti thin film is deposited by DC magnetron sputtering and its thicknesses is well controlled. The ZnO thin film is prepared by sol-gel method using zinc acetate as cation source, 2-methoxiethanol as solvent and monoethanolamine as solution stabilizer. The ZnO film deposition is performed by spin-coating technique and dried at 150 °C on Corning 1737 glass. Due to the conductivity of ZnO/Ag-Ti is dominated by Ag-Ti, the sheet resistance of ZnO/Ag-Ti decrease dramatically as the thickness of Ag-Ti layer increases. However, the transmittances of ZnO/Ag-Ti become unacceptable for TCO application after the thickness of Ag-Ti layer beyond 6 nm. The as-deposited ZnO/Ag-Ti structure has the optical transmittance of 83% @ 500 nm and the low resistivity of 1.2 × 10 -5 Ω-cm. Furthermore, for improving the optical and electrical properties of ZnO/Ag-Ti, the thermal treatment using laser is adopted. Experimental results indicate that the transmittance of ZnO/Ag-Ti is improved from 83% to 89% @ 500 nm with resistivity of 1.02 × 10 -5 Ω-cm after laser drilling. The optical spectrum, the resistance, and the morphology of the ZnO/Ag-Ti will be reported in the study.

  2. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Tunable Anisotropic Absorption of Ag-Embedded SiO2 Thin Films by Oblique Angle Deposition

    NASA Astrophysics Data System (ADS)

    Xiao, Xiu-Di; Dong, Guo-Ping; Shao, Jian-Da; Fan, Zheng-Xiu; He, Hong-Bo; Qi, Hong-Ji

    2009-08-01

    Ag-embedded SiO2 thin films are prepared by oblique angle deposition. Through field emission scanning electron microscopy (SEM), an orientated slanted columnar structure is observed. Energy-dispersive x-ray (EDX) analysis shows the Ag concentration is about 3% in the anisotropic SiO2 matrix. Anisotropic surface plasma resonance (SPR) absorption is observed in the Ag-embedded SiO2 thin films, which is dependent on polarization state and incidence angle of two orthogonal polarized lights and the deposition angle. This means that optical properties and anisotropic SPR absorption can be tunable in Ag-embedded SiO2 thin films. Broadband polarization splitting is also observed and the transmission ratio Tp/Ts between p- and s-polarized lights is up to 2.7 for thin films deposited at α = 70°, which means that Ag-embedded SiO2 thin films are a promising candidate for thin film polarizers.

  3. Amperometric biosensor of SnO2 thin film modified by Pd, In and Ag nanostructure synthesized by CSP method

    NASA Astrophysics Data System (ADS)

    Hassan, Marwa Abdul Muhsien; Hateef, Areej Adnan; Majeed, Aseel Mustafa Abdul; Al-Jabiry, Ali Jasim Mohammed; Jameel, Sabah; Hussian, Haidar Abdul Razaq Abdul

    2013-10-01

    Palladium, Indium and Silver-doped SnO2 thin film was deposited by chemical spray pyrolysis on ITO and porous silicon substrates to be a fast MgSO4·7H2O amperometric biosensor. The prepared SnO2 films were doped by dipping in palladium chloride PdCl2, indium chloride, InCl3 and silver nitrides AgNO3 dissolved in ethanol C2H5OH. The structural and optical properties of the prepared films were studied. The sensitivity behaviors of SnO2, SnO2: Pd, SnO2: In and SnO2: Ag based on the amperometric biosensor to MgSO4·7H2O salts were investigated at room temperature with different doping.

  4. Second-harmonic generation in quaternary atomically thin layered AgInP2S6 crystals

    NASA Astrophysics Data System (ADS)

    Wang, Xingzhi; Du, Kezhao; Liu, Weiwei; Hu, Peng; Lu, Xin; Xu, Weigao; Kloc, Christian; Xiong, Qihua

    2016-09-01

    Nonlinear effects in two-dimensional (2D) atomic layered materials have attracted increasing interest. Here, we report the observation of optical second-harmonic generation (SHG) in two-dimensional atomically thin silver indium phosphorus sulfide (AgInP2S6) crystals, with odd layer thickness. The nonlinear signal facilitates the use of thickness-dependent SHG intensity to investigate the stacking type of this material, while the crystal-orientation dependent SHG intensity of the monolayer sample reveals the rotational symmetry of the AgInP2S6 lattice in plane. Our studies expand the 2D crystal family in nonlinear effect field, which opened considerable promise to the functionalities and potential applications of 2D materials.

  5. Pure Cubic-Phase Hybrid Iodobismuthates AgBi2 I7 for Thin-Film Photovoltaics.

    PubMed

    Kim, Younghoon; Yang, Zhenyu; Jain, Ankit; Voznyy, Oleksandr; Kim, Gi-Hwan; Liu, Min; Quan, Li Na; García de Arquer, F Pelayo; Comin, Riccardo; Fan, James Z; Sargent, Edward H

    2016-08-01

    Bismuth-based hybrid perovskites are candidates for lead-free and air-stable photovoltaics, but poor surface morphologies and a high band-gap energy have previously limited these hybrid perovskites. A new materials processing strategy to produce enhanced bismuth-based thin-film photovoltaic absorbers by incorporation of monovalent silver cations into iodobismuthates is presented. Solution-processed AgBi2 I7 thin films are prepared by spin-coating silver and bismuth precursors dissolved in n-butylamine and annealing under an N2 atmosphere. X-ray diffraction analysis reveals the pure cubic structure (Fd3m) with lattice parameters of a=b=c=12.223 Å. The resultant AgBi2 I7 thin films exhibit dense and pinhole-free surface morphologies with grains ranging in size from 200-800 nm and a low band gap of 1.87 eV suitable for photovoltaic applications. Initial studies produce solar power conversion efficiencies of 1.22 % and excellent stability over at least 10 days under ambient conditions. PMID:27355567

  6. Pure Cubic-Phase Hybrid Iodobismuthates AgBi2 I7 for Thin-Film Photovoltaics.

    PubMed

    Kim, Younghoon; Yang, Zhenyu; Jain, Ankit; Voznyy, Oleksandr; Kim, Gi-Hwan; Liu, Min; Quan, Li Na; García de Arquer, F Pelayo; Comin, Riccardo; Fan, James Z; Sargent, Edward H

    2016-08-01

    Bismuth-based hybrid perovskites are candidates for lead-free and air-stable photovoltaics, but poor surface morphologies and a high band-gap energy have previously limited these hybrid perovskites. A new materials processing strategy to produce enhanced bismuth-based thin-film photovoltaic absorbers by incorporation of monovalent silver cations into iodobismuthates is presented. Solution-processed AgBi2 I7 thin films are prepared by spin-coating silver and bismuth precursors dissolved in n-butylamine and annealing under an N2 atmosphere. X-ray diffraction analysis reveals the pure cubic structure (Fd3m) with lattice parameters of a=b=c=12.223 Å. The resultant AgBi2 I7 thin films exhibit dense and pinhole-free surface morphologies with grains ranging in size from 200-800 nm and a low band gap of 1.87 eV suitable for photovoltaic applications. Initial studies produce solar power conversion efficiencies of 1.22 % and excellent stability over at least 10 days under ambient conditions.

  7. Investigation of nanostructured Pd-Ag/n-ZnO thin film based Schottky junction for methane sensing

    NASA Astrophysics Data System (ADS)

    Roy, S.; Das, S.; Sarkar, C. K.

    2016-07-01

    Undoped nanocrystalline n-type ZnO thin film was deposited by chemical deposition technique on a thermally oxidized p-Si (~5 Ω cm resistivity and <100> orientation) substrate. Formation of stable zinc oxide thin film was confirmed by two-dimensional X-Ray Diffraction (XRD) and EDX analysis. The average crystallite size of the ZnO sample was evaluated as ~50 nm. The surface was characterized by Field Emission Scanning Electron Microscopy (FESEM) and Atomic Force Microscopy (AFM) that confirm the formation of nanocrystalline (grain size ~50 nm) ZnO thin film with surface roughness of ~100 nm. Good conversion of precursor into ZnO thin film in the chemical deposition method was evident by Fourier Transform Infrared Spectroscopy (FTIR). A small peak at 479 cm-1was observed in the FTIR spectrum confirming the formation of quartzite structure of the ZnO. The band gap (~3.44 eV) of the material was calculated from the optical absorption spectroscopy. To prepare Pd-Ag/n-ZnO Schottky junction, Pd-Ag contacts were taken by electron beam evaporation method. I-V characteristics of the junction were studied at different temperatures in inert and reducing ambient (N2 and N2 + CH4) with turn on voltage of around 0.2 V. The parameters like ideality factor ( η), saturation current ( I 0), series resistance ( Rs), and barrier height ( Φ BO) of the junction were calculated in the temperature range 50-200 °C in N2 as well as in 1 % CH4 + N2 ambient. It was observed that the ideality factor decreases in the temperature range 50-200 °C ( η = 12.34 at 50 °C and η = 1.52 at 200 °C) in N2 ambient and η = 1.18 in N2 +CH4 ambient at 200 °C. Schottky Barrier Height ( Φ BO) of the Pd-Ag/n-ZnO junction was found to increase with temperature. A close observation of Pd-Ag/n-ZnO junction in the presence of methane was performed to appreciate its application as methane sensor. The sensing mechanism was illustrated by a simplified energy band diagram.

  8. Characterization of the (Ag,Cu)(In,Ga)Se2 thin film alloy system for solar cells

    NASA Astrophysics Data System (ADS)

    Boyle, Jonathan

    Energy is the underlying factor to human economic activity, and more energy is projected to be needed in the near future and photovoltaics provide a means to supply that energy. Results presented in this dissertation detail material properties of the (Ag,Cu)(In,Ga)Se2 thin film alloy system for use as a solar cell material. Structural and optical properties were determined via X-ray diffraction and UV/Vis/NIR spectrophotometry, respectively. Structural data was analyzed using JADE 2010 software and optical data was analyzed via two different methods. Results of Ag substitution into Cu(In,Ga)Se2 alloy were reconciled with the Jaffe-Wei-Zunger (JWZ) theoretical model, which relates structural and chemical properties of Cu-based ternary chalcopyrite alloys to their optical properties. Dominant phase of the alloy system was identified as chalcopyrite I-42d, Space group 122, with minor secondary phases and order defect phases. No chalcopyrite-chalcopyrite miscibility gap was present in the alloy compositional space, counter to prior literature on bulk polycrystalline materials and thermodynamic calculations performed here, indicating that Ag was successfully substituted into the chalcopyrite lattice. Lattice constant results were consistent with JWZ model, where a O lattice constant closely follows Vegard's rule, cO lattice constant changes at different rates than aO does with composition, and anion displacement is affected by cation radii. Optical results showed bandgap widening with Ag and Ga substitution across the full compositional space, with bowing parameters shown overall to be invariant with cation substitution, counter to expectations. (Ag+Cu)/(In+Ga) ratio effect on bandgap for a limited set of samples is consistent with p-d hybridization effects from JWZ model.

  9. Nurse practitioner (NP)

    MedlinePlus

    ... more states are requiring NPs to have a master's degree and national certification. In some states, NP ... these organizations require that NPs complete an approved master's-level NP program before taking the certification exam. ...

  10. Iodization of rf sputter induced disordered Ag thin films reveals volume plasmon-exciton 'transition'

    SciTech Connect

    Bharathi Mohan, D.; Sunandana, C. S.

    2006-09-15

    Quasiamorphous Ag films of thicknesses ranging from 5 to 30 nm were prepared using rf magnetron sputtering technique and their controlled iodization was carried out for selected durations in the range of 15 min-60 h at room temperature. As deposited Ag and iodized films were characterized using x-ray diffraction (XRD), atomic force microscope (AFM), and optical absorption techniques. From XRD, {gamma} and {beta}+{gamma} (mixed) phases of AgI nanoparticles have been observed for 5-10 and 20-30 nm thick films, respectively. Lattice parameters (a and c) and average strain ({epsilon}) were calculated versus iodization time for {gamma} and {beta}-AgI nanoparticles. Uniform and nonuniform spherically shaped AgI nanoparticles ({approx}20-130 nm) are realized through AFM for 5-10 and 20-30 nm thick films. Optical absorption shows volume plasmons (classified as PR1) for short duration iodization, which ''decay'' upon further iodization to convert to Z{sub 1,2} and Z{sub 3} excitons at 420 and 330 nm, respectively, in the manner of a metal-semiconductor/dielectric phase transition. Ag 'colloidal' particles (classified as PR2) are formed for 5-10 nm thick films and thereby control the {gamma} phase--a significant and applicable effect attributed to critical film thickness. With increasing thickness, a surface strain field lifting the degeneracy of the valence band results in Z{sub 1,2} and Z{sub 3} exciton formation at room temperature. Blueshift in the exciton absorption with decreasing film thickness implies the progressive quantum confinement due to decrease in the particle size. A thickness induced phase transition from {gamma}-AgI to {beta}-AgI is discussed by means of x-ray diffraction and optical absorption studies.

  11. Structural characteristics of thermally evaporated Cu0.5Ag0.5InSe2 thin films

    NASA Astrophysics Data System (ADS)

    Gullu, H. H.; Parlak, M.

    2016-05-01

    In this work, Cu0.5Ag0.5InSe2 (CAIS) thin film samples were prepared by thermal evaporation of Cu, Ag, InSe and Se evaporants sequentially on glass substrates. Following the deposition, annealing processes were applied at different temperatures. The as-grown and annealed CAIS samples were nearly stoichiometric in the detection limit of the compositional measurement. The x-ray diffraction (XRD) measurements revealed that they were in polycrystalline structure with a preferred orientation along the (112) direction. Moreoever, the crystallinity of the films improved with increasing annealing temperature. According to the results of Raman measurements, the highest Raman intensity was found in the A1 mode which is directly proportional to the crystallinity of the samples. The surface properties of the thin films were analyzed by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM). These results showed that there was a Se agglomeration on the deposited film surfaces and with annealing processes segregation effects were observed on the surface of the annealed samples. X-ray photoelectron spectroscopy (XPS) measurements were carried out to get information about surface and near-surface properties of the films. The results from the surface and depth surface analyses of the films were found to be in agreement with the energy dispersive spectroscopy (EDS) analysis.

  12. Plasmonic enhanced optical characteristics of Ag nanostructured ZnO thin films

    NASA Astrophysics Data System (ADS)

    Sarkar, Arijit; Gogurla, Narendar; Shivakiran Bhaktha, B. N.; Ray, Samit K.

    2016-04-01

    We have demonstrated the enhanced photoluminescence and photoconducting characteristics of plasmonic Ag–ZnO films due to the light scattering effect from Ag nanoislands. Ag nanoislands have been prepared on ITO-coated glass substrates by thermal evaporation followed by annealing. Plasmonic Ag–ZnO films have been fabricated by depositing ZnO over Ag nanoislands by sol–gel process. The band-edge emission of ZnO is enhanced for 170 nm sized Ag nanoislands in ZnO as compared to pure ZnO. The defect emission is also found to be quenched simultaneously for plasmonic Ag–ZnO films. The enhancement and quenching of photoluminescence at different wavelengths for Ag–ZnO films can be well understood from the localized surface plasmon resonance of Ag nanoislands. The Ag–ZnO M–S–M photoconductor device showed a tenfold increment in photocurrent and faster photoresponse as compared to the control ZnO device. The enhancement in photoresponse of the device is due to the increased photon absorption in ZnO films via scattering of the incident illumination.

  13. Antifungal activity of Ag:hydroxyapatite thin films synthesized by pulsed laser deposition on Ti and Ti modified by TiO2 nanotubes substrates

    NASA Astrophysics Data System (ADS)

    Eraković, S.; Janković, A.; Ristoscu, C.; Duta, L.; Serban, N.; Visan, A.; Mihailescu, I. N.; Stan, G. E.; Socol, M.; Iordache, O.; Dumitrescu, I.; Luculescu, C. R.; Janaćković, Dj.; Miškovic-Stanković, V.

    2014-02-01

    Hydroxyapatite (HA) is a widely used biomaterial for implant thin films, largely recognized for its excellent capability to chemically bond to hard tissue inducing the osteogenesis without immune response from human tissues. Nowadays, intense research efforts are focused on development of antimicrobial HA doped thin films. In particular, HA doped with Ag (Ag:HA) is expected to inhibit the attachment of microbes and contamination of metallic implant surface. We herewith report on nano-sized HA and Ag:HA thin films synthesized by pulsed laser deposition on pure Ti and Ti modified with 100 nm diameter TiO2 nanotubes (fabricated by anodization of Ti plates) substrates. The HA-based thin films were characterized by SEM, AFM, EDS, FTIR, and XRD. The cytotoxic activity was tested with HEp2 cells against controls. The antifungal efficiency of the deposited layers was tested against the Candida albicans and Aspergillus niger strains. The Ti substrates modified with TiO2 nanotubes covered with Ag:HA thin films showed the highest antifungal activity.

  14. Spectroscopic Ellipsometry Studies of Ag and ZnO Thin Films and Their Interfaces for Thin Film Photovoltaics

    NASA Astrophysics Data System (ADS)

    Sainju, Deepak

    Many modern optical and electronic devices, including photovoltaic devices, consist of multilayered thin film structures. Spectroscopic ellipsometry (SE) is a critically important characterization technique for such multilayers. SE can be applied to measure key parameters related to the structural, optical, and electrical properties of the components of multilayers with high accuracy and precision. One of the key advantages of this non-destructive technique is its capability of monitoring the growth dynamics of thin films in-situ and in real time with monolayer level precision. In this dissertation, the techniques of SE have been applied to study the component layer materials and structures used as back-reflectors and as the transparent contact layers in thin film photovoltaic technologies, including hydrogenated silicon (Si:H), copper indium-gallium diselenide (CIGS), and cadmium telluride (CdTe). The component layer materials, including silver and both intrinsic and doped zinc oxide, are fabricated on crystalline silicon and glass substrates using magnetron sputtering techniques. These thin films are measured in-situ and in real time as well as ex-situ by spectroscopic ellipsometry in order to extract parameters related to the structural properties, such as bulk layer thickness and surface roughness layer thickness and their time evolution, the latter information specific to real time measurements. The index of refraction and extinction coefficient or complex dielectric function of a single unknown layer can also be obtained from the measurement versus photon energy. Applying analytical expressions for these optical properties versus photon energy, parameters that describe electronic transport, such as electrical resistivity and electron scattering time, can be extracted. The SE technique is also performed as the sample is heated in order to derive the effects of annealing on the optical properties and derived electrical transport parameters, as well as the

  15. Coexistent compressive and tensile strain in Ag thin films on Si(1 1 1)-(7×7) surfaces

    NASA Astrophysics Data System (ADS)

    Goswami, D. K.; Bhattacharjee, K.; Satpati, B.; Roy, S.; Kuri, G.; Satyam, P. V.; Dev, B. N.

    2007-09-01

    Growth and strain behavior of thin Ag films on Si substrates have been investigated by scanning tunneling microscopy, cross-sectional transmission electron microscopy and high resolution X-ray diffraction studies. Ag islands formed on Si at room temperature growth show strongly preferred heights and flat top. At low coverage [ ≳1 monolayer (ML)], Ag islands with (1 1 1) orientation containing two atomic layers of Ag are overwhelmingly formed [D.K. Goswami, K. Bhattacharjee, B. Satpati, S. Roy, P.V. Satyam, B.N. Dev, Surf. Sci. 601 (2007) 603]. A thicker (40 ML) annealed film shows two closely spaced Ag(1 1 1) diffraction peaks—one weak and broad and the other narrow and more intense. The broad peak corresponds to an average expansion (0.21%) and the narrow intense peak corresponds to a contraction (0.17%) of the Ag(1 1 1) planar spacing compared to the bulk value. This coexistence of compressive and tensile strain can be explained in terms of changes in the Ag lattice during the heating-cooling cycle due to thermal expansion coefficient mismatch between Ag and Si.

  16. Investigating Quantum Oscillations in the Thermal Coefficient of Resistivity of Ultra-thin Ag Capping Layers on Cu for IC Interconnect Applications

    NASA Astrophysics Data System (ADS)

    Tatem, Elroy

    As the semiconductor industry continues to scale feature sizes, scattering from phonons, surfaces, and grain boundaries result in an increase of metal interconnect resistivity in state-of-the-art integrated circuits (ICs). The interconnect chapter of the 2011 International Technology Roadmap for Semiconductors (ITRS) stated that there are currently no manufacturable solutions in the near term for suitable Cu replacements. Previous studies of thin Ag films deposited on Cu demonstrated oscillations in the electron-phonon interactions within the bilayer system. This thesis investigates oscillations in the resistive properties of the Ag/Cu bilayer system and discusses the applicability of these oscillations to the resistivity challenges facing metal-based IC interconnects. Ag/Cu bilayer films were prepared by physical vapor deposition (PVD). The films were characterized by measuring the electrical resistance of the films at various temperatures and calculating the thermal coefficient of resistance (TCR) for various Ag capping layer thicknesses. Films were further characterized by atomic force microscopy (AFM), Rutherford backscattering (RBS), and scanning electron microscopy (SEM). Patterned Ag-capped Cu lines were fabricated, which exhibited resistive behavior similar to that of the Ag/Cu films. Compared to bare Cu, the resistances of Ag-capped Cu lines and films were lower and exhibited a reduced dependence on temperature. Smaller thermal coefficients of resistivity were also observed for Ag-capped Cu films and patterned lines when compared to Cu alone.

  17. AgGaSe2 thin films grown by chemical close-spaced vapor transport for photovoltaic applications: structural, compositional and optical properties.

    PubMed

    Merschjann, C; Mews, M; Mete, T; Karkatzinou, A; Rusu, M; Korzun, B V; Schorr, S; Schubert-Bischoff, P; Seeger, S; Schedel-Niedrig, Th; Lux-Steiner, M-Ch

    2012-05-01

    Thin films of chalcopyrite AgGaSe(2) have been successfully grown on glass and glass/molybdenum substrates using the technique of chemical close-spaced vapor transport. The high crystallinity of the samples is confirmed by grazing-incidence x-ray diffraction, scanning and transmission electron microscopy, and optical transmission/reflection spectroscopy. Here, two of the three expected direct optical bandgaps are found at 1.77(2) and 1.88(6) eV at 300 K. The lowest bandgap energy at 4 K is estimated to be 1.82(3) eV. Photoluminescence spectroscopy has further revealed the nature of the point defects within the AgGaSe(2), showing evidence for the existence of very shallow acceptor levels of 5(1) and 10(1) meV, and thus suggesting the AgGaSe(2) phase itself to exhibit a p-type conductivity. At the same time, electrical characterization by Hall, Seebeck and four-point-probe measurements indicate properties of a compensated semiconductor. The electrical properties of the investigated thin films are mainly influenced by the presence of Ag(2)Se and Ga(2)O(3) nanometer-scaled surface layers, as well as by Ag(2)Se inclusions in the bulk and Ag clusters at the layers' rear side. PMID:22469870

  18. Temperature behaviour of optical parameters in (Ag3AsS3)0.3(As2S3)0.7 thin films

    NASA Astrophysics Data System (ADS)

    Kutsyk, Mykhailo M.; Ráti, Yosyp Y.; Izai, Vitalii Y.; Makauz, Ivan I.; Studenyak, Ihor P.; Kökényesi, Sandor; Komada, Paweł; Zhailaubayev, Yerkin; Smailov, Nurzhigit

    2015-12-01

    (Ag3AsS3)0.3(As2S3)0.7 thin films were deposited onto a quartz substrate by rapid thermal evaporation. The optical transmission spectra of thin films were measured in the temperature range 77-300 K. It is shown that the absorption edge spectra are described by the Urbach rule. The temperature behaviour of absorption spectra was studied, the temperature dependences of energy position of absorption edge and Urbach energy were investigated. The influence of transition from three-dimensional glass to the two-dimensional thin film as well as influence of Ag3AsS3 introduction into As2S3 on the optical parameters of (Ag3AsS3)0.3(As2S3)0.7 were analysed. The spectral and temperature behaviour or refractive index for (Ag3AsS3)0.3(As2S3)0.7 thin film were studied.

  19. Photocatalytic Properties of TiO2 Thin Films Modified with Ag and Pt Nanoparticles Deposited by Gas Flow Sputtering.

    PubMed

    Maicu, M; Glöss, D; Frach, Peter; Hecker, D; Gerlach, G; Córdoba, José M

    2015-09-01

    In this work, a gas flow sputtering (GFS) process which allows the production and deposition of metal nanoparticles (NPs) in a vacuum environment is described. Aim of the study is to prove the potential of this technology for the fabrication of new TiO2 films with enhanced photocatalytic properties. For this purpose, Ag and Pt NPs have been produced and deposited on photocatalytic float glass coated with TiO2 thin films by magnetron sputtering. The influence of the process parameters and of the metal amount on the final properties of the particles (quantity, size, size distribution, oxidation state etc.,) was widely investigated. Moreover, the effect of the NPs on the photocatalytic activity of the resulting materials was evaluated for the case of the decomposition of stearic acid (SA) during UV-A irradiation. The reduction of the water contact angle (WCA) during the irradiation period was measured in order to test the photo-induced super-hydrophilicity (PSH).

  20. Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses.

    PubMed

    Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C; Altman, Sidney; Schwarz, Udo D; Kyriakides, Themis R; Schroers, Jan

    2016-01-01

    Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.

  1. Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses

    PubMed Central

    Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan

    2016-01-01

    Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design. PMID:27230692

  2. Combinatorial development of antibacterial Zr-Cu-Al-Ag thin film metallic glasses

    NASA Astrophysics Data System (ADS)

    Liu, Yanhui; Padmanabhan, Jagannath; Cheung, Bettina; Liu, Jingbei; Chen, Zheng; Scanley, B. Ellen; Wesolowski, Donna; Pressley, Mariyah; Broadbridge, Christine C.; Altman, Sidney; Schwarz, Udo D.; Kyriakides, Themis R.; Schroers, Jan

    2016-05-01

    Metallic alloys are normally composed of multiple constituent elements in order to achieve integration of a plurality of properties required in technological applications. However, conventional alloy development paradigm, by sequential trial-and-error approach, requires completely unrelated strategies to optimize compositions out of a vast phase space, making alloy development time consuming and labor intensive. Here, we challenge the conventional paradigm by proposing a combinatorial strategy that enables parallel screening of a multitude of alloys. Utilizing a typical metallic glass forming alloy system Zr-Cu-Al-Ag as an example, we demonstrate how glass formation and antibacterial activity, two unrelated properties, can be simultaneously characterized and the optimal composition can be efficiently identified. We found that in the Zr-Cu-Al-Ag alloy system fully glassy phase can be obtained in a wide compositional range by co-sputtering, and antibacterial activity is strongly dependent on alloy compositions. Our results indicate that antibacterial activity is sensitive to Cu and Ag while essentially remains unchanged within a wide range of Zr and Al. The proposed strategy not only facilitates development of high-performing alloys, but also provides a tool to unveil the composition dependence of properties in a highly parallel fashion, which helps the development of new materials by design.

  3. The Role of Annealing Process in Ag-Based BaSnO3 Multilayer Thin Films

    NASA Astrophysics Data System (ADS)

    Wu, Muying; Yu, Shihui; He, Lin; Yang, Lei; Zhang, Weifeng

    2016-08-01

    The BaSnO3/Ag/BaSnO3 multilayer structure was designed and fabricated on a quartz glass by magnetron sputtering, followed by an annealing process at a temperature from 150 to 750 °C in air. In this paper, we investigated the influence of the annealing temperature on the structural, optical, and electrical properties of the multilayers and proposed the mechanisms of conduction and transmittance. The maximum value of the figure of merit of 31.8 × 10-3 Ω-1 was achieved for the BaSnO3/Ag/BaSnO3 multilayer thin films annealed at 150 °C, while the average optical transmittance in the visible ranges was >84 %, the resistivity was 5.71 × 10-5 Ω cm, and the sheet resistance was 5.57 Ω/sq. When annealed at below 600 °C, the values of resistivity and transmittance of the multilayers were within an acceptable range (resistivity <5.0 × 10-4 Ω cm, transmittance >80 %). The observed property of the multilayer film is suitable for the application of transparent conductive electrodes.

  4. The Role of Annealing Process in Ag-Based BaSnO3 Multilayer Thin Films.

    PubMed

    Wu, Muying; Yu, Shihui; He, Lin; Yang, Lei; Zhang, Weifeng

    2016-12-01

    The BaSnO3/Ag/BaSnO3 multilayer structure was designed and fabricated on a quartz glass by magnetron sputtering, followed by an annealing process at a temperature from 150 to 750 °C in air. In this paper, we investigated the influence of the annealing temperature on the structural, optical, and electrical properties of the multilayers and proposed the mechanisms of conduction and transmittance. The maximum value of the figure of merit of 31.8 × 10(-3) Ω(-1) was achieved for the BaSnO3/Ag/BaSnO3 multilayer thin films annealed at 150 °C, while the average optical transmittance in the visible ranges was >84 %, the resistivity was 5.71 × 10(-5) Ω cm, and the sheet resistance was 5.57 Ω/sq. When annealed at below 600 °C, the values of resistivity and transmittance of the multilayers were within an acceptable range (resistivity <5.0 × 10(-4) Ω cm, transmittance >80 %). The observed property of the multilayer film is suitable for the application of transparent conductive electrodes. PMID:27544775

  5. Raman Spectroscopy of the Reaction of Thin Films of Solid-State Benzene with Vapor-Deposited Ag, Mg, and Al

    SciTech Connect

    Schalnat, Matthew C.; Hawkridge, Adam M.; Pemberton, Jeanne E.

    2011-07-21

    Thin films of solid-state benzene at 30 K were reacted with small quantities of vapor-deposited Ag, Mg, and Al under ultrahigh vacuum, and products were monitored using surface Raman spectroscopy. Although Ag and Mg produce small amounts of metal–benzene adduct products, the resulting Raman spectra are dominated by surface enhancement of the normal benzene modes from metallic nanoparticles suggesting rapid Ag or Mg metallization of the film. In contrast, large quantities of Al adduct products are observed. Vibrational modes of the products in all three systems suggest adducts that are formed through a pathway initiated by an electron transfer reaction. The difference in reactivity between these metals is ascribed to differences in ionization potential of the metal atoms; ionization potential values for Ag and Mg are similar but larger than that for Al. These studies demonstrate the importance of atomic parameters, such as ionization potential, in solid-state metal–organic reaction chemistry.

  6. Structural and optical properties of annealed and illuminated (Ag3AsS3)0.6(As2S3)0.4 thin films

    NASA Astrophysics Data System (ADS)

    Studenyak, I. P.; Neimet, Yu. Yu.; Rati, Y. Y.; Stanko, D.; Kranjčec, M.; Kökényesi, S.; Daróci, L.; Bohdan, R.

    2014-11-01

    (Ag3AsS3)0.6(As2S3)0.4 thin films were deposited upon a quartz substrate by rapid thermal evaporation. Structural studies of the as-deposited, annealed and illuminated films were performed using XRD, scanning electron and atomic force microscopies. Surfaces of all the films were found to be covered with Ag-rich crystalline micrometer sized cones. Thermal annealing leads to mechanical deformation of part of the cones and their detachment from the base film surface while the laser illumination leads to the new formations appearance on the surface of thin films. The spectroscopic studies of optical transmission spectra for as-deposited, annealed and illuminated thin films were carried out. The optical absorption spectra in the region of its exponential behaviour were analysed, the dispersion dependences of refractive index as well as their variation after annealing and illumination were investigated.

  7. Incommensurate growth of Co thin film on close-packed Ag(111) surface

    NASA Astrophysics Data System (ADS)

    Barman, Sukanta; Menon, Krishna Kumar S. R.

    2016-05-01

    Growth of ultrathin Co layers on close-packed Ag(111)were investigated by means of Low Energy Electron Diffraction (LEED), X-ray Photoelectron Spectroscopy (XPS) and Angle-resolved Photoemission Spectroscopy(ARPES) techniques. The close-packed hexagonal face of Co(0001), exhibits a lattice misfit about 13% with Ag(111) surface which manipulates the growth to be incommensurate up to a certain thickness. The strain field causes aperiodic height undulation in the sub-angstrom regime of the film which was confirmed by p(1 × 1) LEED pattern along with a 6-fold moiré reconstruction pattern in the lower film thickness (up to ˜2ML). The evolution of the LEED pattern was studied with increasing film coverage. Lattice strain was measured with respect to the relative positions of these double spots as a functionof film thickness. Almost a constant strain (˜13%) in the full range of film thickness explains the moiré pattern formation in order to stabilize the incommensurate growth. For higher film coverages, an epitaxial well-ordered commensurate growth was observed. Core level and valance band electronic structures of these films were studied by XPS and ARPES techniques.

  8. AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films for solar cell applications

    SciTech Connect

    González, J.O.; Shaji, S.; Avellaneda, D.; Castillo, A.G.; Roy, T.K. Das; and others

    2013-05-15

    Highlights: ► AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films were formed by heating Na{sub 2}SeSO{sub 3} dipped Sb{sub 2}S{sub 3}/Ag layers. ► S/Se ratio was varied by changing the dipping time in Na{sub 2}SeSO{sub 3} solution. ► Characterized the films using XRD, XPS, SEM, Optical and electrical measurements. ► Band gap engineering of 1−1.1 eV for x = 0.51 and 0.52 respectively. ► PV Glass/FTO/CdS/AgSb(S{sub x}Se{sub 1−x}){sub 2}/C were prepared showing V{sub oc} = 410 mV, J{sub sc} = 5.7 mA/cm{sup 2}. - Abstract: Silver antimony sulfoselenide (AgSb(S{sub x}Se{sub 1−x}){sub 2}) thin films were prepared by heating glass/Sb{sub 2}S{sub 3}/Ag layers after selenization using sodium selenosulphate solution. First, Sb{sub 2}S{sub 3} thin films were deposited on glass substrates from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3}. Then Ag thin films were thermally evaporated onto glass/Sb{sub 2}S{sub 3}, followed by selenization by dipping in an acidic solution of Na{sub 2}SeSO{sub 3}. The duration of selenium dipping was varied as 30 min and 2 h. The heating condition was at 350 °C for 1 h in vacuum. Analysis of X-ray diffraction pattern of the thin films formed after heating showed the formation of AgSb(S{sub x}Se{sub 1−x}){sub 2}. Morphology and elemental analysis were done by scanning electron microscopy and energy dispersive X-ray detection. Depth profile of composition of the thin films was performed by X-ray Photoelectron Spectroscopy. The spectral study showed the presence of Ag, Sb, S, and Se, and the corresponding binding energy analysis confirmed the formation of AgSb(S{sub x}Se{sub 1−x}){sub 2}. Photovoltaic structures (PV) were prepared using AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films as absorber and CdS thin films as window layers on FTO coated glass substrates. The PV structures were heated at 60–80 °C in air for 1 h to improve ohmic contact. Analysis of J–V characteristics of the PV structures showed V

  9. Evaluation of first crystallization in amorphous Ag-added Ag5.5In6.5Sb59Te29 thin films

    NASA Astrophysics Data System (ADS)

    Song, Ki-Ho; Seo, Jae-Hee; Kim, Jun-Hyong; Lee, Hyun-Yong

    2009-12-01

    In this article, several experimental results were reported for the evaluation of the first crystallization speed (v1st) on the nanosecond time scale as well as the material characteristics of the Ag-added Ag-In-Sb-Te films. The (Ag)x(Ag5.5In6.5Sb59Te29)1-x (x=0, 0.1, and 0.2) films were prepared by thermal evaporation and their phase transformation from an amorphous state to a hexagonal structure via a stable fcc structure was confirmed using x-ray diffraction. Some differences were measured in the optical transmittance (TOP) and absorption between the amorphous and crystalline films in the wavelength (λ) range of 800-3000 nm using an UV-visible-IR spectrophotometer. The v1st values, evaluated using nanopulse reflection response, slightly improved with an increase in the Ag content. For example, the nucleation time/average growth time ratio for the Ag5.5In6.5Sb59Te29 and Ag0.2(Ag5.5In6.5Sb59Te29)0.8 films were approximately 170 ns/70 ns and 110 ns/60 ns, respectively, for an illumination power of 7 mW.

  10. Oxidative Stress Mechanisms Caused by Ag Nanoparticles (NM300K) are Different from Those of AgNO3: Effects in the Soil Invertebrate Enchytraeus crypticus

    PubMed Central

    Ribeiro, Maria J.; Maria, Vera L.; Scott-Fordsmand, Janeck J.; Amorim, Mónica J. B.

    2015-01-01

    The mechanisms of toxicity of Ag nanoparticles (NPs) are unclear, in particular in the terrestrial environment. In this study the effects of AgNP (AgNM300K) were assessed in terms of oxidative stress in the soil worm Enchytraeus crypticus, using a range of biochemical markers [catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR), total glutathione (TG), metallothionein (MT), lipid peroxidation (LPO)]. E. crypticus were exposed during 3 and 7 days (d) to the reproduction EC20, EC50 and EC80 levels of both AgNP and AgNO3. AgNO3 induced oxidative stress earlier (3 d) than AgNP (7 d), both leading to LPO despite the activation of the anti-redox system. MT increased only for AgNP. The Correspondence Analysis showed a clear separation between AgNO3 and AgNP, with e.g., CAT being the main descriptor for AgNP for 7 d. LPO, GST and GPx were for both 3 and 7 d associated with AgNO3, whereas MT and TG were associated with AgNP. These results may reflect a delay in the effects of AgNP compared to AgNO3 due to the slower release of Ag+ ions from the AgNP, although this does not fully explain the observed differences, i.e., we can conclude that there is a nanoparticle effect. PMID:26287225

  11. The effect of Ag diffusion on properties of YBa 2Cu 3O 7- x thin films produced by electron beam deposition techniques

    NASA Astrophysics Data System (ADS)

    Görür, O.; Küçükömeroğlu, T.; Terzioğlu, C.; Varilci, A.; Altunbaş, M.

    2005-01-01

    Superconducting YBa 2Cu 3O 7- x thin films were prepared on pure MgO and Ag/MgO substrates (without and with Ag buffer layer) using an electron beam evaporation technique. The effects of isothermal annealing temperature and Ag diffusion on the crystalline structure and some superconducting properties were investigated by X-ray diffraction, scanning electron microscopy, critical temperature, critical current density and room temperature resistivity measurements. The optimum annealing conditions causing a high degree of preferential orientation with the c-axis perpendicular to the substrates were found to be the isothermal annealing at 930 °C for 5 h. Annealing of films on Ag/MgO substrates is accompanied by Ag diffusion from the buffer layer into YBCO films. The higher rate of crystallization of the YBCO films, the higher degree of c-axis orientation, the higher dense surface morphology, the increased lattice parameter c (by ≈0.1%), the reduced room temperature resistivity (2-3 times), the slightly enchanced critical temperature ( Tc = 92 K at R = 0) and the critical current density ( Jc = 4.2 × 10 5 A/cm 2 at 77 K) were observed for the Ag-doped films (on Ag/MgO substrates) in comparison with those for the undoped films (on MgO substrates). The temperature dependence of the Ag diffusion coefficient in YBCO films in the range 600-800 °C was described by the relation D = 1.9 × 10 -6 exp(-0.73 eV/kT).

  12. Augmentation of thermoelectric performance of VO2 thin films irradiated by 200 MeV Ag9+-ions

    NASA Astrophysics Data System (ADS)

    Khan, G. R.; Kandasami, A.; Bhat, B. A.

    2016-06-01

    Swift Heavy Ion (SHI) irradiation with 200 MeV Ag9+-ion beam at ion fluences of 1E11, 5E11, 1E12, and 5E12 for tuning of electrical transport properties of VO2 thin films fabricated by so-gel technique on alumina substrates has been demonstrated in the present paper. The point defects created by SHI irradiation modulate metal to insulator phase transition temperature, carrier concentration, carrier mobility, electrical conductivity, and Seebeck coefficient of VO2 thin films. The structural properties of the films were characterized by XRD and Raman spectroscopy and crystallite size was found to decrease upon irradiation. The atomic force microscopy revealed that the surface roughness of specimens first decreased and then increased with increasing fluence. Both resistance as well as Seebeck coefficient measurements demonstrated that all the samples exhibit metal-insulator phase transition and the transition temperatures decreases with increasing fluence. Hall effect measurements exhibited that carrier concentration increased continuously with increasing fluence which resulted in an increase of electrical conductivity by several orders of magnitude in the insulating phase. Seebeck coefficient in insulating phase remained almost constant in spite of an increase in the electrical conductivity by several orders of magnitude making SHI irradiation an alternative stratagem for augmentation of thermoelectric performance of the materials. The carrier mobility at room temperature decreased up to the beam fluence of 5E11 and then started increasing whereas Seebeck coefficient in metallic state first increased with increasing ion beam fluence up to 5E11 and thereafter decreased. Variation of these electrical transport parameters has been explained in detail.

  13. Structural and optical properties of Ag-doped copper oxide thin films on polyethylene napthalate substrate prepared by low temperature microwave annealing

    SciTech Connect

    Das, Sayantan; Alford, T. L.

    2013-06-28

    Silver doped cupric oxide thin films are prepared on polyethylene naphthalate (flexible polymer) substrates. Thin films Ag-doped CuO are deposited on the substrate by co-sputtering followed by microwave assisted oxidation of the metal films. The low temperature tolerance of the polymer substrates led to the search for innovative low temperature processing techniques. Cupric oxide is a p-type semiconductor with an indirect band gap and is used as selective absorption layer solar cells. X-ray diffraction identifies the CuO phases. Rutherford backscattering spectrometry measurements confirm the stoichiometry of each copper oxide formed. The surface morphology is determined by atomic force microscopy. The microstructural properties such as crystallite size and the microstrain for (-111) and (111) planes are calculated and discussed. Incorporation of Ag led to the lowering of band gap in CuO. Consequently, it is determined that Ag addition has a strong effect on the structural, morphological, surface, and optical properties of CuO grown on flexible substrates by microwave annealing. Tauc's plot is used to determine the optical band gap of CuO and Ag doped CuO films. The values of the indirect and direct band gap for CuO are found to be 2.02 eV and 3.19 eV, respectively.

  14. The effect of strain induced by Ag underlayer on saturation magnetization of partially ordered Fe{sub 16}N{sub 2} thin films

    SciTech Connect

    Yang, Meiyin; Allard, Lawrence F.; Ji, Nian; Zhang, Xiaowei; Wang, Jian-Ping; Yu, Guang-Hua

    2013-12-09

    Partially ordered Fe-N thin films were grown by a facing target sputtering process on the surface of a (001) Ag underlayer on MgO substrates. It was confirmed by x-ray diffraction that the Ag layer enlarged the in-plane lattice of the Fe-N thin films. Domains of the ordered α″-Fe{sub 16}N{sub 2} phase within an epitaxial (001) α′-Fe{sub x}N phase were identified by electron diffraction and high-resolution aberration-corrected scanning transmission electron microscopy (STEM) methods. STEM dark-field and bright-field images showed the fully ordered structure of the α″-Fe{sub 16}N{sub 2} at the atomic column level. High saturation magnetization(Ms) of 1890 emu/cc was obtained for α″-Fe{sub 16}N{sub 2} on the Ag underlayer, while only 1500 emu/cc was measured for Fe-N on the Fe underlayer. The results are likely due to a tensile strain induced in the α″-Fe{sub 16}N{sub 2} phase by the Ag structure at the interface.

  15. Growth of NaCl on thin epitaxial KCl films on Ag(100) studied by SPA-LEED

    NASA Astrophysics Data System (ADS)

    Marquardt, Christian; Paulheim, Alexander; Sokolowski, Moritz

    2015-11-01

    We investigated the growth of NaCl on thin (100)-oriented films of KCl by spot profile analysis of low energy electron diffraction (SPA-LEED). The underlying question of this investigation was how the system accommodates to the misfit of - 10% between the NaCl and KCl lattices. The KCl films (3 atomic layers thick) were epitaxially grown on a Ag(100) single crystal. We studied the heteroepitaxial growth of NaCl on KCl at 300 K and at 500 K, respectively. At 300 K, the first NaCl monolayer (ML) grows pseudomorphically on the KCl film. From the second layer onward, the NaCl lattice relaxes. The NaCl multilayers roughen, and a small rotational disorder (± 4°) of the NaCl domains is observed. The roughening results from the formation of multilayer islands of limited lateral size due to the misfit to the pseudomorphic first NaCl layer. At a growth temperature of 500 K, no pseudomorphic NaCl layer forms, instead relaxed multilayer island growth of NaCl is observed from the first layer onward. Similarly to the growth at 300 K, we find NaCl multilayer islands of limited lateral size. For both temperatures, we explain this growth behavior by the misfit that makes the adsorption sites at the island edges of the first relaxed NaCl layer less favorable for larger islands, promoting nucleation of multilayer islands.

  16. Photocatalytic Properties of TiO2 Thin Films Modified with Ag and Pt Nanoparticles Deposited by Gas Flow Sputtering.

    PubMed

    Maicu, M; Glöss, D; Frach, Peter; Hecker, D; Gerlach, G; Córdoba, José M

    2015-09-01

    In this work, a gas flow sputtering (GFS) process which allows the production and deposition of metal nanoparticles (NPs) in a vacuum environment is described. Aim of the study is to prove the potential of this technology for the fabrication of new TiO2 films with enhanced photocatalytic properties. For this purpose, Ag and Pt NPs have been produced and deposited on photocatalytic float glass coated with TiO2 thin films by magnetron sputtering. The influence of the process parameters and of the metal amount on the final properties of the particles (quantity, size, size distribution, oxidation state etc.,) was widely investigated. Moreover, the effect of the NPs on the photocatalytic activity of the resulting materials was evaluated for the case of the decomposition of stearic acid (SA) during UV-A irradiation. The reduction of the water contact angle (WCA) during the irradiation period was measured in order to test the photo-induced super-hydrophilicity (PSH). PMID:26716202

  17. Normal zone propagation in superconducting thin-film fault current limiting elements with Au-Ag alloy shunt layers

    NASA Astrophysics Data System (ADS)

    Arai, K.; Yamasaki, H.; Kaiho, K.; Furuse, M.; Nakagawa, Y.; Sohma, M.; Yamaguchi, I.

    2008-02-01

    We have been developing a superconducting fault current limiter (FCL), in which YBCO superconducting thin films with Au-Ag alloy shunt layers are used. We have already achieved high electric fields (>40 Vpeak/cm), which enable the total length of FCL elements to be reduced drastically, thus greatly reducing the cost of FCLs. In this paper, we report the normal zone propagation velocity in our films when over-current was applied to the films at 50 Hz for 100 ms. The velocity plotted against the root-mean square values of the normalized film current showed a common curve or curves. The data were also discussed using the adiabatic theory. As the normal zone propagation velocity was not so fast, we divided one unit film of 120 mm length into two portions, to each of which an external resistance was attached. The test result showed that a high electric field of 45 Vpeak/cm and total voltage of 450 Vpeak were achieved in the first cycle after quenching, and the film withstood the voltage for five cycles. The temperature distribution along the length of the film was also shown.

  18. Influence of a hot and humid environment on thermal transport across the interface between a Ag thin-film line and a substrate

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Noguchi, Kyohei; Saka, Masumi

    2016-04-01

    To evaluate the reliability of Ag thin-film lines for a wide range of applications in electronic devices, knowledge of the thermal transport across the interface between the line and the underlying substrate is of great importance. This is because such thermal transport significantly affects the temperature distribution in the line, the electrical performance of the line and the service life of the device the line is installed on. In this work, we examine the influence of a hot and humid environment on the thermal transport across the interface between a Ag thin-film line and a substrate. By performing a series of current-stressing experiments using the four-point probe method at atmospheric conditions (296 K and 30 RH%) on a Ag thin-film line for different durations of exposure to a hot and humid environment (323 K and 90 RH%), the electrical resistivity was found to increase with the exposure duration. Such an increase is believed to be the result of a decrease in the interfacial thermal conductance, which indicates less thermal transport from the line to the substrate. Moreover, by observing the surface morphology changes in the line and conducting a one-dimensional electro-thermal analysis, such variations can be attributed to the generation and growth of voids within the line, which hinder heat transfer from the line to the substrate through the interface.

  19. Contact resistance improvement using interfacial silver nanoparticles in amorphous indium-zinc-oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Xu, Rui; He, Jian; Song, Yang; Li, Wei; Zaslavsky, A.; Paine, D. C.

    2014-09-01

    We describe an approach to reduce the contact resistance at compositional conducting/semiconducting indium-zinc-oxide (IZO) homojunctions used for contacts in thin film transistors (TFTs). By introducing silver nanoparticles (Ag NPs) at the homojunction interface between the conducting IZO electrodes and the amorphous IZO channel, we reduce the specific contact resistance, obtained by transmission line model measurements, down to ˜10-2 Ω cm2, ˜3 orders of magnitude lower than either NP-free homojunction contacts or solid Ag metal contacts. The resulting back-gated TFTs with Ag NP contacts exhibit good field effect mobility of ˜27 cm2/V s and an on/off ratio >107. We attribute the improved contact resistance to electric field concentration by the Ag NPs.

  20. Contact resistance improvement using interfacial silver nanoparticles in amorphous indium-zinc-oxide thin film transistors

    SciTech Connect

    Xu, Rui; He, Jian; Song, Yang; Li, Wei; Zaslavsky, A.; Paine, D. C.

    2014-09-01

    We describe an approach to reduce the contact resistance at compositional conducting/semiconducting indium-zinc-oxide (IZO) homojunctions used for contacts in thin film transistors (TFTs). By introducing silver nanoparticles (Ag NPs) at the homojunction interface between the conducting IZO electrodes and the amorphous IZO channel, we reduce the specific contact resistance, obtained by transmission line model measurements, down to ∼10{sup −2 }Ω cm{sup 2}, ∼3 orders of magnitude lower than either NP-free homojunction contacts or solid Ag metal contacts. The resulting back-gated TFTs with Ag NP contacts exhibit good field effect mobility of ∼27 cm{sup 2}/V s and an on/off ratio >10{sup 7}. We attribute the improved contact resistance to electric field concentration by the Ag NPs.

  1. The structural studies of Ag containing TiO2-SiO2 gels and thin films deposited on steel

    NASA Astrophysics Data System (ADS)

    Adamczyk, Anna; Rokita, Magdalena

    2016-06-01

    FTIR spectroscopic structural studies of titania-silica monolith samples as well as thin films deposited on steel were described in this work. Thin films were synthesized by the sol-gel method applying the dip coating as separate one-component TiO2 and/or SiO2 layers or as two-component TiO2-SiO2 thin films. Silver nanoparticles were incorporated into the structure from pure SiO2 sol, deposited then as an additional layer in those hybrid multilayers systems. Except the spectroscopic studies, XRD diffraction, SEM microscopy with EDX analysis and AFM microscopy were applied. The structural studies allow to describe and compare the structure and the morphology of thin films, as well those Ag free as Ag containing ones, also by the comparison with the structure of bulk samples. In FTIR spectra, the band observed at about 613 cm-1 can be connected with the presence of the non-tetrahedral cation in the structure and is observed only in the spectra of Ag containing bulk samples and thin films. The bands at 435-467 cm-1 are due to the stretching vibrations of Ti-O bonds or as well to the bending vibrations of O-Si-O one. In the ranges of 779-799 cm-1 and 1027-1098 cm-1, the bands ascribed to the symmetric stretching vibrations and asymmetric vibrations of Si-O-Si connections, respectively, are observed. SEM and AFM images gave the information on the microstructure and the topography of samples surface. XRD measurements confirmed the presence of only amorphous phase in samples up to 500 °C and allowed to observe the tendency of their crystallization.

  2. Structural, morphological and optical properties of Ag-AgO thin films with the effect of increasing film thickness and annealing temperature

    NASA Astrophysics Data System (ADS)

    Pal, Anil Kumar; Bharathi Mohan, D.

    2015-10-01

    Ag films of thickness ranging from 5 to 60 nm were deposited by thermal evaporation technique followed by air annealing process with temperature varying from 50 to 250 °C. Morphological properties such as particle size, shape, surface roughness and number particles density were studied by atomic force microscope (AFM). The structural transition from quasi-amorphous to nanocrystalline to crystalline upon increasing film thickness and annealing temperature were studied. Ag films with smallest particle size and surface roughness were achieved up to film thickness of 7 nm. The possibility of surface oxidation of Ag on both as deposited and annealed films was studied through Raman mapping by using confocal Raman spectroscopy. Ag film was X-ray amorphous even after annealing process up to the film thickness of 7 nm and above which the crystallinity reached maximum at 250 °C. The surface plasmon resonance (SPR) with a symmetric line shape due to dipole-dipole interactions was found to be very strong for film thickness of 5 nm at 100 °C, attributed to the formation of smaller Ag NPs size of ∼22 nm with least size distribution and higher particles number density of ∼1625 μm-2 in a self-organized fashion. With an increase of film thickness and annealing temperature, an asymmetric broad absorption arose due to increase in damping of collective electron oscillation on bulky NPs. Theoretical absorption spectra were simulated using extended Maxwell garnet method showing a decent agreement with experimental data. The real and imaginary parts of dielectric constants were determined and plotted for different film thicknesses of as deposited Ag films. Even though the film is oxidized at the surface level, it still can be used for plasmonic sensor applications however the film thickness should be approximately 7 nm for the enhanced result.

  3. High-quality reproducible PLD Y-Ba-Cu-O:Ag thin films up to 4 inch diameter for microwave applications

    NASA Astrophysics Data System (ADS)

    Lorenz, Michael; Hochmuth, Holger; Natusch, Dieter; Grundmann, Marius

    2002-08-01

    Large-area pulsed laser deposition (PLD) has reached a state in terms of film quality and reproducibility which makes possible now real applications of PLD-YBa 2Cu 3O 7- δ (YBCO) thin films on both sides of R-plane sapphire substrates as HTSC devices in mobile communication systems. Bandpass filters optimized from PLD-YBCO thin films presently fulfill the requirements of the main national companies which are active in future communication techniques. A relatively simple PLD arrangement with fixed laser plume and rotating substrate, with an offset between the laser plume and the center of the substrate is employed to deposit laterally homogeneous 4 inch diameter Ag-doped YBCO thin films. With the experience of more than 1000 double-sided 3 inch diameter films a high degree of homogeneity and reproducibility of jc and Rs is reached. The extension up to 8 inch substrate diameter will increase the productivity of the flexible PLD technique considerably.

  4. Structuring by field enhancement of glass, Ag, Au, and Co thin films using short pulse laser ablation

    SciTech Connect

    Ulmeanu, M.; Zamfirescu, M.; Rusen, L.; Luculescu, C.; Moldovan, A.; Stratan, A.; Dabu, R.

    2009-12-01

    Single pulse laser ablation of glass, Ag, Au, and Co thin films was experimentally investigated with a laser pulse width of 400 ps at a wavelength of 532 nm both in the far and near fields. In the far-field regime, the electromagnetic field results from a focused laser beam, while the near-field regime is realized by a combination of the focused laser beam incident on a spherical colloidal particle. For the near-field experiments we have used polystyrene colloidal particles of 700 nm diameter self-assembled or spin coated on top of the surfaces. Laser fluences applied are in the range of 0.01-10 J/cm{sup 2}. The diameter and the morphologies of the ablated holes were investigated by optical microscopy, profilometry, scanning electron microscopy, and atomic force microscopy. The dependence of the shape of the holes reflects the fluence regime and the thermophysical properties, i.e., melting temperature and thermal diffusivity of the surfaces involved in the experiments. We give quantitative data about the fluence threshold, diameter, and depth ablation dependence for the far and near fields and discuss their values with respect to the enhancement factor of the intensity of the electromagnetic field due to the use of the colloidal particles. Theoretical estimations of the intensity enhancement were done using the finite-difference time-domain method by using the RSOFT software. The application of near fields allows structuring of the surfaces with structure dimension in the order of 100 nm and even below.

  5. The influence of electron confinement, quantum size effects, and film morphology on the dispersion and the damping of plasmonic modes in Ag and Au thin films

    NASA Astrophysics Data System (ADS)

    Politano, Antonio; Chiarello, Gennaro

    2015-05-01

    Plasmons are collective longitudinal modes of charge fluctuation in metal samples excited by an external electric field. Surface plasmons (SPs) are waves that propagate along the surface of a conductor. SPs find applications in magneto-optic data storage, optics, microscopy, and catalysis. The investigation of SPs in silver and gold is relevant as these materials are extensively used in plasmonics. The theoretical approach for calculating plasmon modes in noble metals is complicated by the existence of localized d electrons near the Fermi level. Nevertheless, recent calculations based on linear response theory and time-dependent local density approximation adequately describe the dispersion and damping of SPs in noble metals. Furthermore, in thin films the electronic response is influenced by electron quantum confinement. Confined electrons modify the dynamical screening processes at the film/substrate interface by introducing novel properties with potential applications. The presence of quantum well states in the Ag and Au overlayer affects both the dispersion relation of SP frequency and the damping processes of the SP. Recent calculations indicate the emergence of acoustic surface plasmons (ASP) in Ag thin films exhibiting quantum well states. The slope of the dispersion of ASP decreases with film thickness. High-resolution electron energy loss spectroscopy (HREELS) is the main experimental technique for investigating collective electronic excitations, with adequate resolution in both the energy and momentum domains to investigate surface modes. Herein we review on recent progress of research on collective electronic excitations in Ag and Au films deposited on single-crystal substrates.

  6. Enhanced Thermochromic Properties and Solar-Heat Shielding Ability of W(x)V(1-x)O2 Thin Films with Ag Nanowires Capping Layers.

    PubMed

    Zhao, Li Li; Miao, Lei; Liu, Cheng Yan; Wang, Hai Long; Tanemura, Sakae; Sun, Li Xian; Gao, Xiang; Zhou, Jian Hua

    2015-11-01

    Considerable efforts have been made to shift the phase transition temperature of metal-doped vanadium dioxide (VO2) films nearer the ambient temperature while maintain the excellent thermochromic properties simultaneously. Here, we describe a facile and economic solution-based method to fabricate W-doped VO2 (V(1-x)W(x)O2) thin films with excellent thermochromic properties for the application of smart windows. The substitutional doping of tungsten atoms notably reduces the phase transition temperature to the ambient temperature and retains the excellent thermochromic property. Furthermore, Ag nanowires (NWs) are employed as capping layers to effectively decrease the thermal emissivity from 0.833 to 0.603, while the original near infrared region (NIR) modulation ability is not severely affected. Besides, the Ag NWs layers further depress the phase transition temperature as well as the hysteresis loop width, which is important to the fenestration application. These solution-grown Ag NWs/V(1-x)W(x)O2 thin films exhibit excellent solar modulation ability, narrowed hysteresis loop width as well as low thermal emissivity, which provide a promising perspective into the practical application of VO2-based smart windows.

  7. Enhanced Thermochromic Properties and Solar-Heat Shielding Ability of W(x)V(1-x)O2 Thin Films with Ag Nanowires Capping Layers.

    PubMed

    Zhao, Li Li; Miao, Lei; Liu, Cheng Yan; Wang, Hai Long; Tanemura, Sakae; Sun, Li Xian; Gao, Xiang; Zhou, Jian Hua

    2015-11-01

    Considerable efforts have been made to shift the phase transition temperature of metal-doped vanadium dioxide (VO2) films nearer the ambient temperature while maintain the excellent thermochromic properties simultaneously. Here, we describe a facile and economic solution-based method to fabricate W-doped VO2 (V(1-x)W(x)O2) thin films with excellent thermochromic properties for the application of smart windows. The substitutional doping of tungsten atoms notably reduces the phase transition temperature to the ambient temperature and retains the excellent thermochromic property. Furthermore, Ag nanowires (NWs) are employed as capping layers to effectively decrease the thermal emissivity from 0.833 to 0.603, while the original near infrared region (NIR) modulation ability is not severely affected. Besides, the Ag NWs layers further depress the phase transition temperature as well as the hysteresis loop width, which is important to the fenestration application. These solution-grown Ag NWs/V(1-x)W(x)O2 thin films exhibit excellent solar modulation ability, narrowed hysteresis loop width as well as low thermal emissivity, which provide a promising perspective into the practical application of VO2-based smart windows. PMID:26726666

  8. NP Science Network Requirements

    SciTech Connect

    Dart, Eli; Rotman, Lauren; Tierney, Brian

    2011-08-26

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

  9. Study on the fabrication of transparent electrodes by using a thermal-roll imprinted Ag mesh and anATO thin film

    NASA Astrophysics Data System (ADS)

    Kim, Sung Jin; Choi, Kyoon; Choi, Se Young

    2016-03-01

    Transparent conductive films have been widely studied because of their potential applications in optoelectronic devices such as paper displays, dye-sensitized solar cells (DSSCs), organic lighting-emitting diodes (OLEDs), organic solar cells and so on. In this paper, we report on a low-resistance, a high-transparents conductive film that can be applied as It a flexible device substrate. In order to the fabricate transparent conductive film, we used a high-resolution roll imprinting method. The following steps were performed: The design and manufacture of an electroforming stamp mold, the fabrication of high resolution roll imprinted on flexible film, and the manufacture of an Ag grid that was filled by using a doctor blade process with a nano-sized Ag paste. Then on patterned Its films, antimony tin oxide was coated with ATO sol solution by using bar the coating method. The fabricated ATO/Ag mesh electrode showed good flexibility, and It exhibited a high optical transmittance of 85.3% in the visible wavelength and a sheet resistance of 41 Ω/sq. Furthermore, the bending test for mechanical properties showed that the ATO/Ag thin film had good flexibility.

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

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

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

  11. YBa2Cu3O7-δ - ag Sputtered Thin Films on MgO (100) and LaAlO3 (100) Biased and Unbiased Substrates

    NASA Astrophysics Data System (ADS)

    Moshfegh, A. Z.; Akhavan, O.; Salamati, H.; Kameli, P.; Akhavan, M.

    2000-09-01

    In this investigation, we have deposited YBa2Cu3O7-δ - Ag thin films on various biased and unbiased substrates, including MgO (100), LaAlO3 (100) and Si (111), using a single stoichiometric composite target of YBa2Cu3O7-δ with 10 wt.% Ag content, applying DC sputtering technique. The growth parameters are varied as following: sputtering gas pressure PAr = 100 - 300 mtorr, sputtering power P = 30 - 80 W, substrate bias voltage Vb= 0 - 220 V and film thickness t = 500 - 5000 Å. An optimum bias voltage of Vb= - 100 V was obtained under our experimental conditions. The post annealed (930°C for 1 hr in O2 environment) films exhibit superconducting state with Tc (onset) of about 40 K for biased (on - axis), and 86 K for unbiased (off- axis) post annealed (800 ° C, 3 hr) films grown over both MgO(100) and LaAlO3 (100) substrates. According to our SEM analysis, Ag particles are uniformly distributed in the annealed films with average grain size of about 0.3 μm located mostly at the grain boundaries. PIXE compositional analysis of the deposited films indicates deficiency of Cu and Ba for unannealed and Cu rich concentration for the annealed YBCO - Ag films grown over unbiased LaAlO3 (100) substrate.

  12. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

    Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

  13. Ferromagnetism in 200-MeV Ag{sup +15}-ion-irradiated Co-implanted ZnO thin films

    SciTech Connect

    Angadi, Basavaraj; Jung, Y.S.; Choi, Won-Kook; Kumar, Ravi; Jeong, K.; Shin, S.W.; Lee, J.H.; Song, J.H.; Wasi Khan, M.; Srivastava, J.P.

    2006-04-03

    Structural, electrical resistivity, and magnetization properties of 200-MeV Ag{sup +15}-ion-irradiated Co-implanted ZnO thin films are presented. The structural studies show the presence of Co clusters whose size is found to increase with increase of Co implantation. The implanted films were irradiated with 200-MeV Ag{sup +15} ions to fluence of 1x10{sup 12} ions/cm{sup 2}. The Co clusters on irradiation dissolve in the ZnO matrix. The electrical resistivity of the irradiated samples is lowered to half. The magnetization hysteresis measurements show ferromagnetic behavior at 300 K, and the coercive field increases with the Co implantation. The ferromagnetism at room temperature is confirmed by magnetic force microscopy measurements. The results are explained on the basis of the close interplay between the electrical and the magnetic properties.

  14. The growth mode and microstructure of Ag-doped YBa 2Cu 3O 7-δ thin films prepared by dual beam pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    Xu, S. Y.; Ong, C. K.; You, L. P.; Li, J.; Wang, S. J.

    Ag-doped c-axis YBa 2Cu 3O 7-δ thin films were fabricated by using dual-beam pulsed-laser deposition. When a small amount of silver was doped in the film grown at 700 °C, the Jc value was obviously enhanced. The temperature dependence of Jc was found proportional to ( 1- T/T c0 ) {3}/{2} at T close to Tc). In the films grown at 730 °C, we observed long bar-like structures with lengths in tens of μm, oriented along or at 45° to the a/ b axes of the film. The bars consisted mainly a-axis YBCO grains and a mixture of polycrystalline and amorphous oxides. Defects on substrate surface and growth temperature were found dominating in formation of the bars, which could be attributed to a Ag-assisted diffusion mechanism during the deposition process.

  15. Optical and electrical properties and phonon drag effect in low temperature TEP measurements of AgSbSe2 thin films

    NASA Astrophysics Data System (ADS)

    Namitha Asokan, T.; Urmila, K. S.; Jacob, Rajani; Reena Philip, Rachel; Okram, G. S.; Ganesan, V.; Pradeep, B.

    2014-05-01

    Polycrystalline thin films of silver antimony selenide have been deposited using a reactive evaporation technique onto an ultrasonically cleaned glass substrate at a vacuum of 10-5 torr. The preparative parameters, like substrate temperature and incident fluxes, have been properly controlled in order to get stoichiometric, good quality and reproducible thin film samples. The samples are characterized by XRD, SEM, AFM and a UV—vis—NIR spectrophotometer. The prepared sample is found to be polycrystalline in nature. From the XRD pattern, the average particle size and lattice constant are calculated. The dislocation density, strain and number of crystallites per unit area are evaluated using the average particle size. The dependence of the electrical conductivity on the temperature has also been studied and the prepared AgSbSe2 samples are semiconducting in nature. The AgSbSe2 thin films exhibited an indirect allowed optical transition with a band gap of 0.64 eV. The compound exhibits promising thermoelectric properties, a large Seebeck coefficient of 30 mV/K at 48 K due to strong phonon electron interaction. It shows a strong temperature dependence on thermoelectric properties, including the inversion of a dominant carrier type from p to n over a low temperature range 9-300 K, which is explained on the basis of a phonon drag effect.

  16. A comparative study on in situ grown superconducting YBCO and YBCO-Ag thin films by PLD on polycrystalline SmBa2NbO6 substrate

    NASA Astrophysics Data System (ADS)

    Kurian, J.; John, Asha M.; Wariar, P. R. S.; Sajith, P. K.; Koshy, J.; Pai, S. P.; Pinto, R.

    2000-02-01

    The development and characterization of SmBa2NbO6, which is a new ceramic substrate material for the YBa2Cu3O7-icons/Journals/Common/delta" ALT="delta" ALIGN="MIDDLE"/> superconductor, are reported. SmBa2NbO6 has a complex cubic perovskite structure with lattice constant a = 8.524 Å. The dielectric properties of SmBa2NbO6 are in a range suitable for its use as a substrate for microwave applications. SmBa2NbO6 was found to have a thermal conductivity of 77 W m-1 K-1 and a thermal expansion coefficient of 7.8 × 10-6 °C-1 at room temperature. Superconducting YBa2 Cu3O7-icons/Journals/Common/delta" ALT="delta" ALIGN="MIDDLE"/> and YBa2Cu3O7-icons/Journals/Common/delta" ALT="delta" ALIGN="MIDDLE"/> -Ag thin films have been grown in situ on polycrystalline SmBa2NbO6 by the pulsed laser ablation technique. The films exhibited (00l) orientation of an orthorhombic YBa2 Cu3O7-icons/Journals/Common/delta" ALT="delta" ALIGN="MIDDLE"/> phase and gave a zero resistivity superconducting transition (TC(0)) at 90 K with a transition width of ~1.5 K. The critical current density of YBCO-Ag thin films grown on polycrystalline SmBa2NbO6 substrate was ~3 × 105 A cm-2 at 77 K. A comparative study of YBCO and YBCO-Ag thin films developed on polycrystalline SmBa2NbO6 substrate by PLD based on the crystallinity, orientation and critical current density of the YBCO film is discussed in detail.

  17. Layer by layer growth of silver chloride nanoparticle within the pore channels of SBA-15/SO3H mesoporous silica (AgClNP/SBA-15/SO3K): Synthesis, characterization and antibacterial properties

    NASA Astrophysics Data System (ADS)

    Rostamnia, Sadegh; Doustkhah, Esmail; Estakhri, Saba; Karimi, Ziba

    2016-02-01

    The growth of silver chloride nanoparticles within the pore channels of functionalized SBA-15 mesoporous was achieved by sequential dipping steps in alternating bath of potassium chloride and silver nitrate under ultrasound irradiation at pH=9. The effects of sequential dipping steps in growth of the AgCl nanoparticles have been studied. The growth and formation of AgCl nanoparticles inside the sulfonated SBA-15 were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Antibacterial activity of the synthesized materials was investigated against Escherichia coli (E.coli) using the conventional diffusion-disc method. The materials showed high antibacterial activity.

  18. Reactive combinatorial synthesis and characterization of a gradient Ag-Ti oxide thin film with antibacterial properties.

    PubMed

    Unosson, Erik; Rodriguez, Daniel; Welch, Ken; Engqvist, Håkan

    2015-01-01

    The growing demand for orthopedic and dental implants has spurred researchers to develop multifunctional coatings, combining tissue integration with antibacterial features. A possible strategy to endow titanium (Ti) with antibacterial properties is by incorporating silver (Ag), but designing a structure with adequate Ag(+) release while maintaining biocompatibility has been shown difficult. To further explore the composition-structure-property relationships between Ag and Ti, and its effects against bacteria, this study utilized a combinatorial approach to manufacture and test a single sample containing a binary Ag-Ti oxide gradient. The sample, sputter-deposited in a reactive (O2) environment using a custom-built combinatorial physical vapor deposition system, was shown to be effective against Staphylococcus aureus with viability reductions ranging from 17 to above 99%, depending on the amount of Ag(+) released from its different parts. The Ag content along the gradient ranged from 35 to 62 wt.%, but it was found that structural properties such as varied porosity and degree of crystallinity, rather than the amount of incorporated Ag, governed the Ag(+) release and resulting antibacterial activity. The coating also demonstrated in vitro apatite-forming abilities, where structural variety along the sample was shown to alter the hydrophilic behavior, with the degree of hydroxyapatite deposition varying accordingly. By means of combinatorial synthesis, a single gradient sample was able to display intricate compositional and structural features affecting its biological response, which would otherwise require a series of coatings. The current findings suggest that future implant coatings incorporating Ag as an antibacterial agent could be structurally enhanced to better suit clinical requirements.

  19. Microstructure of Co/X (X=Cu,Ag,Au) epitaxial thin films grown on Al{sub 2}O{sub 3}(0001) substrates

    SciTech Connect

    Ohtake, Mitsuru; Akita, Yuta; Futamoto, Masaaki; Kirino, Fumiyoshi

    2007-05-01

    Epitaxial thin films of Co/X (X=Cu,Ag,Au) were prepared on Al{sub 2}O{sub 3}(0001) substrates at substrate temperatures of 100 and 300 degree sign C by UHV molecular beam epitaxy. A complicated microstructure was realized for the epitaxial thin films. In-situ reflection high-energy electron diffraction observation has shown that X atoms of the buffer layer segregated to the surface during Co layer deposition, and it yielded a unique epitaxial granular structure. The structure consists of small Co grains buried in the X buffer layer, where both the magnetic small Co grains and the nonmagnetic X layer are epitaxially grown on the single crystal substrate. The structure varied depending on the X element and the substrate temperature. The crystal structure of Co grains is influenced by the buffer layer material and determined to be hcp and fcc structures for the buffer layer materials of Au and Cu, respectively.

  20. Ultra-thin L1{sub 0}-FePt for perpendicular anisotropy L1{sub 0}-FePt/Ag/[Co/Pd]{sub 30} pseudo spin valves

    SciTech Connect

    Ho, Pin; Chow, Gan Moog; Chen, Jing-Sheng; Han, Guchang; He, Kaihua

    2014-05-07

    Perpendicular anisotropy L1{sub 0}-FePt/Ag/[Co/Pd]{sub 30} pseudo spin valves (PSVs) with ultra-thin L1{sub 0}-FePt alloy free layer possessing high anisotropy and thermal stability have been fabricated and studied. The thickness of the L1{sub 0}-FePt layer was varied between 2 and 4 nm. The PSV became increasingly decoupled with reduced L1{sub 0}-FePt thickness due to the larger difference between the coercivity of the L1{sub 0}-FePt and [Co/Pd]{sub 30} films. The PSV with an ultra-thin L1{sub 0}-FePt free layer of 2 nm displayed a high K{sub u} of 2.21 × 10{sup 7} ergs/cm{sup 3}, high thermal stability of 84 and a largest giant magnetoresistance of 0.54%.

  1. A first principle study of encapsulated and functionalized silicon nanotube of chirality (6,6) with monoatomically thin metal wires of Ag, Au and Cu

    NASA Astrophysics Data System (ADS)

    Kumar Chandel, Surjeet; Kumar, Arun; Ahluwalia, P. K.; Sharma, Raman

    2015-04-01

    First principle calculations have been performed to study the influence of interaction of monoatomically thin metal nanowires of Ag, Au and Cu placed inside (encapsulation) and outside (functionalization) the silicon nanotube having armchair conformation with chirality (6,6). The cohesive energy for all the encapsulated and functionalized systems under study was found to be almost same. In comparison to the pristine silicon nanotube (SiNT) which is found to be semiconducting in nature, all the encapsulated and functionalized systems of SiNT are found to be metallic in nature. The calculated electronic band structures show that the conductance in case of Ag, Au and Cu nanowires encapsulation is 2G0. However, its value for functionalized Ag, Au and Cu nanowires is found to be 1G0, 2G0 and 4G0 for the outside positioning of nanowires respectively. Optical properties of all the encapsulated and functionalized SiNTs have been studied. All the systems under study show reflectivity in the infrared (IR) region and behave as non-absorbing transparent conductors in the visible region.

  2. Enhancement in the excitonic spontaneous emission rates for Si nanocrystal multi-layers covered with thin films of Au, Ag, and Al.

    PubMed

    Estrin, Y; Rich, D H; Rozenfeld, N; Arad-Vosk, N; Ron, A; Sa'ar, A

    2015-10-30

    The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation. Spatially, spectrally, and temporally resolved CL was used to measure the excitonic lifetime of the SiNCs in metal-covered and bare regions of the same samples. The observed enhancement in the SER for the metal-covered SiNCs, relative to the SER for the bare sample, is attributed to a coupling of the SiNC excitons with surface plasmon polaritons (SPPs) of the thin metal films. A maximum SER enhancement of ∼2.0, 1.4 and 1.2 was observed for the Ag, Au, and Al films, respectively, at a temperature of 55 K. The three chosen plasmonic metals of Ag, Au, and Al facilitate an interesting comparison of the exciton-SPP coupling for metal films that exhibit varying differences between the surface plasmon energy, ω(sp), and the SiNC excitonic emission energy. A modeling of the temperature dependence of the Purcell enhancement factor, Fp, was performed and included the temperature dependence of the dielectric properties of the metals. PMID:26436289

  3. Enhancement in the excitonic spontaneous emission rates for Si nanocrystal multi-layers covered with thin films of Au, Ag, and Al

    NASA Astrophysics Data System (ADS)

    Estrin, Y.; Rich, D. H.; Rozenfeld, N.; Arad-Vosk, N.; Ron, A.; Sa'ar, A.

    2015-10-01

    The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation. Spatially, spectrally, and temporally resolved CL was used to measure the excitonic lifetime of the SiNCs in metal-covered and bare regions of the same samples. The observed enhancement in the SER for the metal-covered SiNCs, relative to the SER for the bare sample, is attributed to a coupling of the SiNC excitons with surface plasmon polaritons (SPPs) of the thin metal films. A maximum SER enhancement of ˜2.0, 1.4 and 1.2 was observed for the Ag, Au, and Al films, respectively, at a temperature of 55 K. The three chosen plasmonic metals of Ag, Au, and Al facilitate an interesting comparison of the exciton-SPP coupling for metal films that exhibit varying differences between the surface plasmon energy, ωsp, and the SiNC excitonic emission energy. A modeling of the temperature dependence of the Purcell enhancement factor, Fp, was performed and included the temperature dependence of the dielectric properties of the metals.

  4. Enhancement in the excitonic spontaneous emission rates for Si nanocrystal multi-layers covered with thin films of Au, Ag, and Al.

    PubMed

    Estrin, Y; Rich, D H; Rozenfeld, N; Arad-Vosk, N; Ron, A; Sa'ar, A

    2015-10-30

    The enhancement in the spontaneous emission rate (SER) for Ag, Au, and Al films on multilayer Si nanocrystals (SiNCs) was probed with time-resolved cathodoluminescence (CL). The SiNCs were grown on Si(100) using plasma enhanced chemical vapor deposition. Electron-hole pairs were generated in the metal-covered SiNCs by injecting a pulsed high-energy electron beam through the thin metal films, which is found to be an ideal method of excitation for plasmonic quantum heterostructures and nanostructures that are opaque to laser or light excitation. Spatially, spectrally, and temporally resolved CL was used to measure the excitonic lifetime of the SiNCs in metal-covered and bare regions of the same samples. The observed enhancement in the SER for the metal-covered SiNCs, relative to the SER for the bare sample, is attributed to a coupling of the SiNC excitons with surface plasmon polaritons (SPPs) of the thin metal films. A maximum SER enhancement of ∼2.0, 1.4 and 1.2 was observed for the Ag, Au, and Al films, respectively, at a temperature of 55 K. The three chosen plasmonic metals of Ag, Au, and Al facilitate an interesting comparison of the exciton-SPP coupling for metal films that exhibit varying differences between the surface plasmon energy, ω(sp), and the SiNC excitonic emission energy. A modeling of the temperature dependence of the Purcell enhancement factor, Fp, was performed and included the temperature dependence of the dielectric properties of the metals.

  5. In vitro antibacterial properties and UV induced response from Staphylococcus epidermidis on Ag/Ti oxide thin films.

    PubMed

    Unosson, Erik; Morgenstern, Matthias; Engqvist, Håkan; Welch, Ken

    2016-03-01

    Implanted materials are susceptible to bacterial colonization and biofilm formation, which can result in severe infection and lost implant function. UV induced photocatalytic disinfection on TiO2 and release of Ag(+) ions are two promising strategies to combat such events, and can be combined for improved efficiency. In the current study, a combinatorial physical vapor deposition technique was utilized to construct a gradient coating between Ag and Ti oxide, and the coating was evaluated for antibacterial properties in darkness and under UV light against Staphylococcus epidermidis. The findings revealed a potent antibacterial effect in darkness due to Ag(+) release, with near full elimination (97%) of viable bacteria and visible cell lysis on Ag dominated surfaces. The photocatalytic activity, however, was demonstrated poor due to low TiO2 crystallinity, and UV light irradiation of the coating did not contribute to the antibacterial effect. On the contrary, bacterial viability was in several instances higher after UV illumination, proposing a UV induced SOS response from the bacteria that limited the reduction rate during Ag(+) exposure. Such secondary effects should thus be considered in the development of multifunctional coatings that rely on UV activation.

  6. Influence of surface features on the adhesion of Staphylococcus epidermidis to Ag-TiCN thin films

    NASA Astrophysics Data System (ADS)

    Carvalho, Isabel; Henriques, Mariana; Oliveira, João Carlos; Filipa Almeida Alves, Cristiana; Piedade, Ana Paula; Carvalho, Sandra

    2013-06-01

    Staphylococcus epidermidis has emerged as one of the major nosocomial pathogens associated with infections of implanted medical devices. The initial adhesion of these organisms to the surface of biomaterials is assumed to be an important stage in their colonization. The main objective of this work is to assess the influence of surface features on the adhesion of S. epidermidis to Ag-TiCN coatings deposited by dc reactive magnetron sputtering. The structural results obtained by x-ray diffraction show that the coatings crystallize in a B1-NaCl crystal structure typical of TiC0.3N0.7. The increase of Ag content promoted the formation of Ag crystalline phases. According to the results obtained with atomic force microscopy, a decrease on the surface roughness of the films from 39 to 7 nm is observed as the Ag content increases from 0 to 15 at.%. Surface energy results show that the increase of Ag promotes an increase in hydrophobicity. Bacterial adhesion and biofilm formation on coatings were assessed by the enumeration of the number of viable cells. The results showed that the surface with lower roughness and higher hydrophobicity leads to greater bacterial adhesion and biofilm formation, highlighting that surface morphology and hydrophobicity rule the colonization of materials.

  7. In vitro antibacterial properties and UV induced response from Staphylococcus epidermidis on Ag/Ti oxide thin films.

    PubMed

    Unosson, Erik; Morgenstern, Matthias; Engqvist, Håkan; Welch, Ken

    2016-03-01

    Implanted materials are susceptible to bacterial colonization and biofilm formation, which can result in severe infection and lost implant function. UV induced photocatalytic disinfection on TiO2 and release of Ag(+) ions are two promising strategies to combat such events, and can be combined for improved efficiency. In the current study, a combinatorial physical vapor deposition technique was utilized to construct a gradient coating between Ag and Ti oxide, and the coating was evaluated for antibacterial properties in darkness and under UV light against Staphylococcus epidermidis. The findings revealed a potent antibacterial effect in darkness due to Ag(+) release, with near full elimination (97%) of viable bacteria and visible cell lysis on Ag dominated surfaces. The photocatalytic activity, however, was demonstrated poor due to low TiO2 crystallinity, and UV light irradiation of the coating did not contribute to the antibacterial effect. On the contrary, bacterial viability was in several instances higher after UV illumination, proposing a UV induced SOS response from the bacteria that limited the reduction rate during Ag(+) exposure. Such secondary effects should thus be considered in the development of multifunctional coatings that rely on UV activation. PMID:26758896

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  10. Low-cost and high-power-density resistive fault-current limiting elements using YBCO thin films and Au-Ag alloy shunt layers

    NASA Astrophysics Data System (ADS)

    Yamasaki, H.; Arai, K.; Furuse, M.; Kaiho, K.; Nakagawa, Y.

    2006-06-01

    We propose a new design for the high-temperature superconducting thin-film faultcurrent limiter (FCL), which uses high-resistivity Au-Ag alloy shunt layers instead of the pure gold (or silver) shunt layers conventionally used. An FCL element (5 mm wide and 40 mm long) with a YBCO thin film (THEVA) and a parallel inductively-wound shunt resistor successfully withstood very high electric field (> 44 Vpeak/cm) for 5 cycles (0.1 sec) after switching, and achieved a very high switching power density, ~2.0 kVA/cm2. We confirmed similar maximum tolerable electric field (>40 Vpeak/cm, limited by power supply) in a larger sample (1 cm × 6 cm). The composition of our FCL element is very simple, and the achieved power density is more than five times higher than conventional devices, which leads to a dramatic reduction in the amount of expensive superconducting thin films. We made a conceptual design and cost estimation of our FCL elements used in a typical 6.6 kV FCL.

  11. Optoelectronic characterization of wide-bandgap (AgCu)(InGa)Se 2 thin-film polycrystalline solar cells including the role of the intrinsic zinc oxide layer

    NASA Astrophysics Data System (ADS)

    Obahiagbon, Uwadiae

    Experiments and simulations were conducted to vary the thickness and the sheet resistance of the high resistance (HR) ZnO layer in polycrystalline thin film (AgCu)(GaIn)Se2 (ACIGS) solar cells. The effect of varying these parameters on the electric field distribution, depletion width and hence capacitance were studied by SCAPS simulation. Devices were then fabricated and characterized by a number of optoelectronic techniques. Thin film CIGS has received a lot of attention, for its use as an absorber layer for thin film solar cells. However, the addition of Silver (Ag) to the CIGS alloy system increases the band gap as indicated from optical transmission measurements and thus higher open circuit voltage (Voc) could be obtained. Furthermore, addition of Ag lowers the melting temperature of the alloy and it is expected that this lowers the defect densities in the absorber and thus leads to higher performance. Transient photocapacitance analysis on ACIGS devices shows sharper band edge indicating lower disorder than CIGS. Presently there is a lack of fundamental knowledge relating film characteristics to device properties and performance. This is due to the fact that some features in the present solar cell structure have been optimized empirically. The goal of this research effort was to develop a fundamental and detailed understanding of the device operation as well as the loss mechanism(s) limiting these devices. Recombination mechanisms in finished ACIGS solar cell devices was studied using advanced admittance techniques (AS, DLCP, CV) to identify electronically active defect state(s) and to study their impact on electronic properties and device performance. Analysis of various optoelectronic measurements of ACIGS solar cells provided useful feedback regarding the impact on device performance of the HR ZnO layer. It was found that thickness between 10-100 nm had negligible impact on performance but reducing the thickness to 0 nm resulted in huge variability in all

  12. Transport of engineered silver (Ag) nanoparticles through partially fractured sandstones.

    PubMed

    Neukum, Christoph; Braun, Anika; Azzam, Rafig

    2014-08-01

    Transport behavior and fate of engineered silver nanoparticles (AgNP) in the subsurface is of major interest concerning soil and groundwater protection in order to avoid groundwater contamination of vital resources. Sandstone aquifers are important groundwater resources which are frequently used for public water supply in many regions of the world. The objective of this study is to get a better understanding of AgNP transport behavior in partially fractured sandstones. We executed AgNP transport studies on partially fissured sandstone drilling cores in laboratory experiments. The AgNP concentration and AgNP size in the effluent were analyzed using flow field-flow fractionation mainly. We employed inverse mathematical models on the measured AgNP breakthrough curves to identify and quantify relevant transport processes. Physicochemical filtration, time-dependent blocking due to filling of favorable attachment sites and colloid-facilitated transport were identified as the major processes for AgNP mobility. Physicochemical filtration was found to depend on solute chemistry, mineralogy, pore size distribution and probably on physical and chemical heterogeneity. Compared to AgNP transport in undisturbed sandstone matrix reported in the literature, their mobility in partially fissured sandstone is enhanced probably due to larger void spaces and higher hydraulic conductivity.

  13. A comparative study of optical and radiative characteristics of X-ray-induced luminescent defects in Ag-doped glass and LiF thin films and their applications in 2-D imaging

    NASA Astrophysics Data System (ADS)

    Kurobori, T.; Miyamoto, Y.; Maruyama, Y.; Yamamoto, T.; Sasaki, T.

    2014-05-01

    We report novel disk-type X-ray two-dimensional (2-D) imaging detectors utilising Ag-doped phosphate glass and lithium fluoride (LiF) thin films based on the radiophotoluminescence (RPL) and photoluminescence (PL) phenomena, respectively. The accumulated X-ray doses written in the form of atomic-scale Ag-related luminescent centres in Ag-doped glass and F-aggregated centres in LiF thin films were rapidly reconstructed as a dose distribution using a homemade readout system. The 2-D images reconstructed from the RPL and PL detectors are compared with that from the optically stimulated luminescence (OSL) detector. In addition, the optical and dosimetric characteristics of LiF thin films are investigated and evaluated. The possibilities of dose distributions with a high spatial resolution on the order of microns over large areas, a wide dynamic range covering 11 orders of magnitude and a non-destructive readout are successfully demonstrated by combining the Ag-doped glass with LiF thin films.

  14. Ion-modulated nonlinear electronic transport in carbon nanotube bundle/RbAg4I5 thin film composite nanostructures

    NASA Astrophysics Data System (ADS)

    Sun, Jia-Lin; Zhang, Wei; Wei, Jinquan; Gu, Bingfu

    2014-01-01

    We have explored the ion-modulated electronic transport properties of mixed ionic-electronic conductor (MIEC) composite nanostructures made of superionic conductor RbAg4I5 films and carbon nanotube (CNT) bundle spiderwebs. Our experimental and theoretical studies indicate that the formation of ion-electron bound states (IEBSs) leads to strong ion-electron interference effect and interesting electronic transport of CNT, such as nonlinear current-voltage (I-V) characteristics and novel temperature dependence of the current. With increasing temperature, the hybrid nanostructures show rich phases with different dependence of current on temperature, which is related to the structural phase transition of RbAg4I5 and the transition of dissociation of IEBSs. The ion-modulation of the electric conductivity in such MIEC composite nanostructures with great tunability has been used to design new ionic-electronic composite nano-devices with function like field effect transistor.

  15. Improved optical and electrical properties of 200 MeV Ag{sup 15+} irradiated 3 wt% 'Li' doped MoO{sub 3} thin film

    SciTech Connect

    Kovendhan, M.; Mohan, R.; Joseph, D. Paul; Manimuthu, P.; Venkateswaran, C.; Sambasivam, S.; Singh, J. P.; Asokan, K.

    2013-02-05

    The lithium (3 wt%) doped MoO{sub 3} thin film was prepared by spray deposition onto ITO substrate at 325 Degree-Sign C. The film of thickness 577 nm was irradiated with 200 MeV Ag{sup 15+} ion beams at a fluence of 5 Multiplication-Sign 10{sup 12} ions/cm{sup 2}. The XRD pattern confirmed that the pristine film is polycrystalline with orthorhombic symmetry. Upon irradiation, the film turned amorphous. The sharp Raman peak in pristine film at 993 cm{sup -1} is due to the terminal oxygen of {alpha}-MoO{sub 3} phase. Optical transparency of the film increased upon irradiation. Large red shift was observed in both direct and indirect band gaps. Electrical transport property study shows that the carrier concentration increased by one order for the irradiated film.

  16. 200 MeV Ag15+ ion beam irradiation effects on spray deposited 5 wt% `Li' doped V2O5 thin film

    NASA Astrophysics Data System (ADS)

    Kovendhan, M.; Joseph, D. Paul; Manimuthu, P.; Sendilkumar, A.; Asokan, K.; Venkateswaran, C.; Mohan, R.

    2016-05-01

    Lithium 5 wt% doped V2O5 thin film was deposited onto ITO substrate by spray pyrolysis technique. The substrate temperature was kept at 450 °C. 200 MeV Ag15+ ion beams at a fluence of 5×1012 ions/cm2 was irradiated on 5 wt% `Li' doped V2O5 film of thickness 1367 nm. The XRD pattern confirms that the pristine film is non stoichiometry with orthorhombic structure and upon irradiation the crystallinity decreased and an obvious textured growth along (020) plane is induced. Raman peak observed at 917 cm-1 is due to oxygen deficiency. Upon irradiation, the optical transparency and band gap of the film decreased. Electrical transport property study shows that the resistivity increased by one order for the irradiated film.

  17. An analysis of the x-ray linear dichroism spectrum for NiO thin films grown on vicinal Ag(001)

    SciTech Connect

    Wu, Y.Z.; Zhao, Y.; Arenholz, E.; Young, A.T.; Sinkovic, B.; Qiu, Z.Q.

    2008-05-10

    Antiferromagnetic (AFM) NiO thin films are grown epitaxially on vicinal Ag(118) substrate and investigated by x-ray linear dichroism (XLD). We find that the NiO AFM spin exhibits an in-plane spin reorientation transition from parallel to perpendicular to the step edges with increasing the NiO film thickness. In addition to the conventional L{sub 2} adsorption edge, x-ray linear dichroism (XLD) effect at the Ni L{sub 3} adsorption edge is also measured and analyzed. The result identifies a small energy shift of the L{sub 3} peak. Temperature-dependent measurement confirms that the observed XLD effect in this system at the normal incidence of the x-rays originates entirely from the NiO magnetic ordering.

  18. Study of semiconducting parameters in dark as well as in presence of light for Se90X10 (X=Ag,In) thin films

    NASA Astrophysics Data System (ADS)

    Singh, N. K.; Kumar, Anjani; Kumar, D.; Shukla, S.

    2016-05-01

    The present paper reports the study of semiconducting parameters (activation energy and pre-exponential factor) in glassy samples of Se90X10 (X= Ag, In) in dark as well as in presence of light. Temperature dependence of dark and photo-conductivity is measured in amorphous thin films in the temperature range 300-378 K and in the intensity range 2000-18000 Lux. A straight line between lnσ0 and ΔE indicates the presence of Meyer - Neldel (MN) rule in dark as well as in presence of light. Linear dependence of ln(σ0) on ΔE in case of amorphous material indicate that the conduction band tails a finite energy distance towards the valence band and a Fermi level which is controlled by fixed dominant hole levels deeper in the gap.

  19. The growth, structure, and thermal stability of vapor deposited ultra-thin metal films: Rh on Ag(100), Au on Pd(110), and Pt on Pd(110)

    SciTech Connect

    Schmitz, P.

    1990-09-21

    The growth, structure, and thermal stability of ultra-thin metal films (Rh on Ag(100); Au on Pd(110) and Pt on Pd(110)) is investigated using surface sensitive techniques. The three systems studied present a variety of differing characteristics which can contribute to the growth mode, two-dimensional structure, and thermal stability of the films. The main factors contributing to the differing properties of the three systems presented here are: (1) the different substrate morphologies; (2) the differences in surface free energies between the overlayer and the substrate; (3) the degree of lattice mismatch for a particular system; and (4) the extent of miscibility of the two metals. 200 refs., 38 figs.

  20. Comparison of Ag and SiO2 Nanoparticles for Light Trapping Applications in Silicon Thin Film Solar Cells.

    PubMed

    Theuring, Martin; Wang, Peng Hui; Vehse, Martin; Steenhoff, Volker; von Maydell, Karsten; Agert, Carsten; Brolo, Alexandre G

    2014-10-01

    Plasmonic and photonic light trapping structures can significantly improve the efficiency of solar cells. This work presents an experimental and computational comparison of identically shaped metallic (Ag) and nonmetallic (SiO2) nanoparticles integrated to the back contact of amorphous silicon solar cells. Our results show comparable performance for both samples, suggesting that minor influence arises from the nanoparticle material. Particularly, no additional beneficial effect of the plasmonic features due to metallic nanoparticles could be observed. PMID:26278435

  1. Magnetic disorder in diluted FexM100-x granular thin films (M=Au, Ag, Cu; x < 10 at.%).

    PubMed

    Alba Venero, D; Fernández Barquín, L; Alonso, J; Fdez-Gubieda, M L; Rodríguez Fernández, L; Boada, R; Chaboy, J

    2013-07-10

    Nanogranular thin films of Fe7Au93, Fe7Ag93 and Fe9Cu91 have been sputtered onto Si(100) substrates with the aim of studying the magnetic interactions. X-ray diffraction shows a major noble metal matrix with broad peaks stemming from (111) textured fcc-Au, Ag and Cu. The noble metal forms a nanogranular environment, as confirmed by transmission electron microscopy, with mean particle sizes below 10 nm. The high magnetoresistance (>6%) reveals the existence of Fe nanoparticles. X-ray absorption near edge spectroscopy confirms the presence of a bcc-Fe atom arrangement and some dissolved Fe atoms in the matrix, and XMCD shows the polarization of Au by the Fe nanoparticles. DC-magnetization displays a field-dependent irreversibility produced by the freezing of magnetic nanoparticles into a superspin-glass state. The hysteresis loops remain unsaturated at 5 K and 45 kOe. The coercivity displays a sharp temperature decrease towards a minimum below 50 K, levelling off at higher values, reaching Hc = 200 Oe at 300 K. Annealing of FeAu results in a double-peak zero field cooled magnetization and a slight decrease of the coercivity. The interpretation of the results supports the presence of Fe nanoparticles embedded in the major noble matrix, with some diluted Fe atoms/clusters. PMID:23765439

  2. Effect of thickness and Ti interlayers on stresses and texture transformations in thin Ag films during thermal cycling

    SciTech Connect

    Baker, Shefford P.; Saha, Krishanu; Shu, Jonathan B.

    2013-11-04

    The driving forces for the (111) to (100) texture transformation often observed during annealing of thin face-centered cubic metal films were investigated. Thin passivated silver films were produced with and without Ti adhesion layers. Stresses were measured in situ during heating to induce the texture transformation, and the texture was characterized using x-ray diffraction. Sufficiently thin films did not transform and sufficiently thick films transformed fully. Intermediate thickness films transformed to an extent dependent on thickness, leading to stable mixed textures. In the prevailing thermodynamic model, texture transformation is attributed to minimization of strain and interface energies. However, calculations using the measured stresses, known elastic constants, and estimated interface energies in this model reveal that the stresses are not sufficient to cause the texture transformation and, furthermore, that variations in interface energy cannot lead to the observed behavior. The results suggest that neither the interface energy nor the stress plays decisive roles in the texture transformation.

  3. Assembly of Submicron Sized Ag, Co, and Ni Particles Into Thin Films at Liquid/Liquid Interfaces.

    PubMed

    Al Chaghouri, Hanan; Malik, Mohammad Azad; Thomas, P John; O'Brien, Paul

    2016-05-01

    Submicron sized particles of Ag, Co and Ni were synthesised by reducing metal salts in ethylene glycol (EG) in the presence of polyvinylpyrrolidone (PVP). These particles on dispersion in water when held in contact with a toluene layer were found to assemble into dense films extending over large areas at the interface between the two liquids. The effect of reaction conditions (solvent, precursor concentration, temperature) on the synthesis and assembly of the particles was studied. The characteristics of the interfacial deposits and the particulate dispersions were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy and dynamic light scattering (DLS). PMID:27483942

  4. Temperature studies of optical parameters of (Ag3AsS3)0.6(As2S3)0.4 thin films prepared by rapid thermal evaporation and pulse laser deposition

    NASA Astrophysics Data System (ADS)

    Studenyak, I. P.; Kutsyk, M. M.; Buchuk, M. Yu.; Rati, Y. Y.; Neimet, Yu. Yu.; Izai, V. Yu.; Kökényesi, S.; Nemec, P.

    2016-02-01

    (Ag3AsS3)0.6(As2S3)0.4 thin films were deposited using rapid thermal evaporation (RTE) and pulse laser deposition (PLD) techniques. Ag-enriched micrometre-sized cones (RTE) and bubbles (PLD) were observed on the thin film surface. Optical transmission spectra of the thin films were studied in the temperature range 77-300 K. The Urbach behaviour of the optical absorption edge in the thin films due to strong electron-phonon interaction was observed, the main parameters of the Urbach absorption edge were determined. Temperature dependences of the energy position of the exponential absorption edge and the Urbach energy are well described in the Einstein model. Dispersion and temperature dependences of refractive indices were analysed; a non-linear increase of the refractive indices with temperature was revealed. Disordering processes in the thin films were studied and compared with bulk composites, the differences between the thin films prepared by RTE and PLD were analysed.

  5. Modification of energy band alignment and electric properties of Pt/Ba0.6Sr0.4TiO3/Pt thin-film ferroelectric varactors by Ag impurities at interfaces

    NASA Astrophysics Data System (ADS)

    Hirsch, S.; Komissinskiy, P.; Flege, S.; Li, S.; Rachut, K.; Klein, A.; Alff, L.

    2014-06-01

    We report on the effects of Ag impurities at interfaces of parallel-plate Pt/Ba0.6Sr0.4TiO3/Pt thin film ferroelectric varactors. Ag impurities occur at the interfaces due to diffusion of Ag from colloidal silver paint used to attach the varactor samples with their back side to the plate heated at 600-750 °C during deposition of Ba0.6Sr0.4TiO3. X-ray photoelectron spectroscopy and secondary ion mass spectrometry suggest that amount and distribution of Ag adsorbed at the interfaces depend strongly on the adsorbent surface layer. In particular, Ag preferentially accumulates on top of the Pt bottom electrode. The presence of Ag significantly reduces the barrier height between Pt and Ba0.6Sr0.4TiO3 leading to an increased leakage current density and, thus, to a severe degradation of the varactor performance.

  6. Modification of energy band alignment and electric properties of Pt/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}/Pt thin-film ferroelectric varactors by Ag impurities at interfaces

    SciTech Connect

    Hirsch, S.; Komissinskiy, P. Flege, S.; Li, S.; Rachut, K.; Klein, A.; Alff, L.

    2014-06-28

    We report on the effects of Ag impurities at interfaces of parallel-plate Pt/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}/Pt thin film ferroelectric varactors. Ag impurities occur at the interfaces due to diffusion of Ag from colloidal silver paint used to attach the varactor samples with their back side to the plate heated at 600–750 °C during deposition of Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}. X-ray photoelectron spectroscopy and secondary ion mass spectrometry suggest that amount and distribution of Ag adsorbed at the interfaces depend strongly on the adsorbent surface layer. In particular, Ag preferentially accumulates on top of the Pt bottom electrode. The presence of Ag significantly reduces the barrier height between Pt and Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} leading to an increased leakage current density and, thus, to a severe degradation of the varactor performance.

  7. Effect of 100 MeV Ag+7 ion irradiation on the bulk and surface magnetic properties of Co-Fe-Si thin films

    NASA Astrophysics Data System (ADS)

    Hysen, T.; Geetha, P.; Al-Harthi, Salim; Al-Omari, I. A.; Lisha, R.; Ramanujan, R. V.; Sakthikumar, D.; Avasthi, D. K.; Anantharaman, M. R.

    2014-12-01

    Thin films of Co-Fe-Si were vacuum evaporated on pre-cleaned float glass substrates employing thermal evaporation. The films were subsequently irradiated with 100 MeV Ag+7 ions at fluences of 1×1011, 1×1012 and 1×1013 ions/cm2. The pristine and irradiated samples were subjected to surface analysis using Atomic Force Microscopy (AFM), Vibrating Sample Magnetometry (VSM) and Magneto Optic Kerr Effect (MOKE) measurements. The as deposited film has a root mean square roughness (Rq) of 8.9 nm and an average roughness of (Ra) 5.6 nm. Irradiation of the as deposited films with 100 MeV Ag7+ ions modifies the surface morphology. Irradiating with ions at fluences of 1×1011 ions/cm2 smoothens the mesoscopic hill-like structures, and then, at 1×1012 ions/cm2 new surface structures are created. When the fluence is further increased to 1×1013 ions/cm2 an increase in the surface roughness is observed. The MOKE loop of as prepared film indicated a squareness ratio of 0.62. As the film is irradiated with fluences of 1×1011 ions/cm2, 1×1012 ions/cm2 and 1×1013 ions/cm2 the squareness ratio changes to 0.76, 0.8 and 0.86 respectively. This enhancement in squareness ratio towards 1 is a typical feature when the exchange interaction starts to dominates the inherent anisotropies in the system. The variation in surface magnetisation is explained based on the variations in surface roughness with swift heavy ion (SHI) irradiation.

  8. 500 V/200 A fault current limiter modules made of large-area MOD-YBa2Cu3O7 thin films with high-resistivity Au-Ag alloy shunt layers

    NASA Astrophysics Data System (ADS)

    Yamasaki, H.; Arai, K.; Kaiho, K.; Nakagawa, Y.; Sohma, M.; Kondo, W.; Yamaguchi, I.; Matsui, H.; Kumagai, T.; Natori, N.; Higuchi, N.

    2009-12-01

    We developed 500 Vrms/ 200 Arms superconducting thin-film fault current limiter (FCL) modules that can withstand high electric fields (E>30 Vrms cm-1) by using large-area YBa2Cu3O7 (YBCO) thin films with high-resistivity Au-Ag alloy shunt layers. Au-Ag alloy films about 60 nm thick were sputter-deposited on YBCO/CeO2/sapphire films (2.7 cm × 20 cm) prepared using a fluorine-free MOD method. Each 20 cm long Au-Ag/YBCO film was then divided into three segments (each ~5.7 cm long) by four Ag electrodes deposited on the Au-Ag layer, resulting in an effective length of 17 cm. The 500 V/200 A FCL modules were then fabricated by first connecting two of the segmented films in parallel using Ag-sheathed Bi-2223 superconducting tapes and then connecting in parallel an external resistor and a capacitor for each segment to protect the Au-Ag/YBCO film from hot spots. Switching tests using a short-circuit generator revealed that all the modules carried a superconducting ac current of >=237 Arms and that modules prepared with YBCO films having a relatively homogeneous critical current Ic distribution successfully withstood >=515 Vrms for five cycles without any damage. These results demonstrate that (a) the FCL modules fabricated here successfully achieved the rated current of 200 Arms and rated voltage of 500 Vrms and (b) total area of the YBCO films on sapphire substrates required for the 500 V/200 A (100 kV A) module was less than one-third that for conventional thin-film FCL modules that use gold shunt layers, leading to the significantly reduced cost of thin-film FCLs. Film damage due to hot spots depended on the difference in Ic between the two parallel-connected films and on the inhomogeneity of the Ic distribution in the film, and is most probably due to nonlinear current flows at the moment of quenching that cause local overheating.

  9. Speciation of Np(V) uptake by Opalinus Clay using synchrotron microbeam techniques.

    PubMed

    Fröhlich, Daniel R; Amayri, Samer; Drebert, Jakob; Grolimund, Daniel; Huth, Joachim; Kaplan, Ugras; Krause, Joachim; Reich, Tobias

    2012-11-01

    Synchrotron-based X-ray absorption spectroscopy has been used to determine the chemical speciation of Np sorbed on Opalinus Clay (OPA, Mont Terri, Switzerland), a natural argillaceous rock revealing a micro-scale heterogeneity. Different sorption and diffusion samples with Np(V) were prepared for spatially resolved molecular-level investigations. Thin sections of OPA contacted with Np(V) solution under aerobic and anaerobic conditions as well as a diffusion sample were analysed spatially resolved. Micro-X-ray fluorescence (μ-XRF) mapping has been used to determine the elemental distributions of Np, Fe and Ca. Regions of high Np concentration were subsequently investigated by micro-X-ray absorption fine structure spectroscopy to determine the oxidation state of Np. Further, micro-X-ray diffraction (μ-XRD) was employed to gain knowledge about reactive crystalline mineral phases in the vicinity of Np enrichments. One thin section was also analysed by electron microprobe to determine the elemental distributions of the lighter elements (especially Si and Al), which represent the main elements of OPA. The results show that in most samples, Np spots with considerable amounts of Np(IV) could be found even when the experiments were carried out in air. In some cases, almost pure Np(IV) L(III)-edge X-ray absorption near-edge structure spectra were recorded. In the case of the anaerobic sample, the μ-XRF mapping showed a clear correlation between Np and Fe, indicating that the reduction of Np(V) is caused by an iron(II)-containing mineral which could be identified by μ-XRD as pyrite. These spatially resolved investigations were complemented by extended X-ray absorption fine structure measurements of powder samples from batch experiments under aerobic and anaerobic conditions to determine the structural parameters of the near-neighbour environment of sorbed Np.

  10. Evolution of structural and magnetic properties of Co-doped TiO2 thin films irradiated with 100 MeV Ag7+ ions

    NASA Astrophysics Data System (ADS)

    Mohanty, P.; Singh, V. P.; Mishra, N. C.; Ojha, S.; Kanjilal, D.; Rath, Chandana

    2014-08-01

    In continuation to our earlier studies where we have shown room temperature ferromagnetism observed in TiO2 and Co-doped TiO2 (CTO) thin films independent of their phase (Mohanty et al 2012 J. Phys. D: Appl. Phys. 45 325301), here the modifications in structure and magnetic properties in CTO thin films using 100 MeV Ag7+ ion irradiation are reported. Owing to the important role of defects in tailoring the magnetic properties of the material, we vary the ion fluence from 5 × 1011 to 1 × 1012 ions cm-2 to create post-deposition defects. While the film deposited under 0.1 mTorr oxygen partial pressure retains its crystallinity showing radiation-resistant behaviour even at a fluence of 1 × 1012 ions cm-2, films deposited under 1 to 300 mTorr oxygen partial pressure becomes almost amorphous at the same fluence. Using Poisson's law, the diameter of the amorphized region surrounding the ion path is calculated to be ˜4.2 nm from the x-ray diffraction peak intensity ((1 1 0) for rutile phase) as a function of ion fluence. The saturation magnetization (Ms) decreases exponentially similar to the decrease in x-ray peak intensity with fluence, indicating magnetic disordered region surrounding the ion path. The diameter of the magnetic disordered region is found to be ˜6.6 nm which is larger than the diameter of the amorphized latent track. Therefore, it is confirmed that swift heavy ion irradiation induces a more significant magnetic disorder than the structural disorder.

  11. Investigation on the dielectric response of NdMnO3/LSAT thin films: Effect of 200 MeV Ag+15 ion irradiation

    NASA Astrophysics Data System (ADS)

    Udeshi, Malay; Vyas, Brinda; Trivedi, Priyanka; Katba, Savan; Ravalia, Ashish; Solanki, P. S.; Shah, N. A.; Asokan, K.; Ojha, S.; Kuberkar, D. G.

    2015-12-01

    We report the results of the modifications in structural and dielectric behaviour of pulsed laser deposited NdMnO3 manganite thin films grown on (1 0 0) single crystalline (LaAlO3)0.3 (Sr2AlTaO6)0.7 substrate irradiated with the 200 MeV Ag+15 ion irradiation having different fluences, ∼5 × 1010, ∼5 × 1011, ∼5 × 1012 ions/cm2. Structural strain was quantified using analysis of X-ray Diffraction data while Rutherford Backscattering measurements were performed on pristine NdMnO3 film to confirm the elemental composition, thickness and oxygen content. Dielectric measurements performed on all the irradiated films show that, the dielectric constant decreases with increase in ion fluence which has been correlated with the irradiation induced increase in strain at the film-substrate interface. The dielectric relaxation behaviour of pristine and irradiated NdMnO3 films have been understood by fitting the dielectric data using the Cole-Cole plots.

  12. Impact of 100 MeV Ag7+ SHI irradiation fluence and N incorporation on structural, optical, electrical and gas sensing properties of ZnO thin films

    NASA Astrophysics Data System (ADS)

    Balakrishnan, L.; Gokul Raj, S.; Meher, S. R.; Asokan, K.; Alex, Z. C.

    2015-06-01

    In the present study, we have investigated the influence of Ag7+ ion irradiation fluence and N incorporation on structural, optical, electrical and gas sensing properties of ZnO thin films. The X-ray diffraction analysis reveals the retainment of ZnO wurtzite structure even at higher fluence irradiation with slight decrease in crystallinity. Photoluminescence and Hall effect measurement analysis showed an increase in density of defects for high ion fluence irradiation. Atomic force microscope analysis shows that the films irradiated at high ion fluence have vertical standing needle-like morphology and also have high value of roughness compared with the films irradiated at low ion fluence. The ammonia and methanol gas sensing properties of the films have been studied at different operating temperature and gas concentration. It conveys that the films have selectivity towards ammonia than methanol and also that the films irradiated at high ion fluence exhibit better sensitivity, low response and recovery times compared with the films irradiated at low ion fluence. The film grown in oxygen ambience and irradiated at high ion fluence showed good sensing characteristics at all temperatures even at room temperature.

  13. Microstructure and temperature dependence of microwave penetration depth of Ag doped Y 1Ba 2Cu 3O 7- x thin films

    NASA Astrophysics Data System (ADS)

    Kaur, Davinder; Pai, S. P.; Jesudasan, J.; Pinto, R.

    2004-06-01

    We report the measurements of magnetic penetration depth λ( T) of Ag-doped YBa 2Cu 3O 7- δ (YBCO) thin films in the thickness range 1500-4000 A and temperature range 18-88 K. The films are in situ grown by laser ablation on <1 0 0> LaAlO 3 substrates. The penetration depth measurements are performed by microstrip resonator technique. A correlation of λ( T) with the film microstructure observed with atomic force microscopy has shown that λ( T) depends critically on the film microstructure. Temperature dependence of magnetic penetration depth has also been studied for best quality films. The experimental results are discussed in terms of BCS theory (s-wave pairing) and d-wave Pairing with and without unitary scattering. The results are found to be best fitted to the d-wave model with unitary scattering limit. Near Tc, we have also compare the (3D) XY critical regime and the Ginzburg-Landau (GL) behaviour.

  14. Mechanical, structural and thermal properties of Ag-Cu and ZnO reinforced polylactide nanocomposite films.

    PubMed

    Ahmed, Jasim; Arfat, Yasir Ali; Castro-Aguirre, Edgar; Auras, Rafael

    2016-05-01

    Plasticized polylactic acid (PLA) based nanocomposite films were prepared by incorporating polyethylene glycol (PEG) and two selected nanoparticles (NPs) [silver-copper (Ag-Cu) alloy (<100 nm) and zinc oxide (ZnO) (<50 and <100 nm)] through solvent casting method. Incorporation of Ag-Cu alloy into the PLA/PEG matrix increased the glass transition temperature (Tg) significantly. The crystallinity of the nanocomposites (NCs) was significantly influenced by NP incorporation as evidenced from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The PLA nanocomposite reinforced with NPs exhibited much higher tensile strength than that of PLA/PEG blend. Melt rheology of NCs exhibited a shear-thinning behavior. The mechanical property drastically reduced with a loading of NPs, which is associated with degradation of PLA. SEM micrographs exhibited that both Ag-Cu alloy and ZnO NPs were dispersed well in the PLA film matrix. PMID:26893045

  15. Influence of substrate temperature on the properties of pulsed laser deposited silver nanoparticle thin films and their application in SERS detection of bovine serum albumin

    NASA Astrophysics Data System (ADS)

    Kamakshi, Koppole; Silva, J. P. B.; Sekhar, K. C.; Marslin, Gregory; Moreira, J. Agostinho; Conde, O.; Almeida, A.; Pereira, M.; Gomes, M. J. M.

    2016-05-01

    The effect of substrate temperature ( T s) on electrical conductance, surface plasmon resonance (SPR), and surface-enhanced Raman scattering (SERS) activity of silver nanoparticle (AgNP) thin films is presented. AgNP films are grown on glass substrates by pulsed laser deposition in a controlled Ar atmosphere at a pressure of 0.1 mbar and varying T s. Different T s results in different morphologies, as observed by scanning electron microscopy. The effect of interparticle distance on the electrical conductance of AgNPs is highlighted. The current-voltage characteristics display negative resistance effect and is attributed to the charge trapping process in AgNPs. The film deposited at room temperature presents a SPR peak at λ = 460 nm, and its wavelength first increases until T s reaches 300 °C and then decreases with further increasing T s. The quantitative analysis of SERS studies reveals that SERS intensity of bovine serum albumin (BSA) adsorbed on AgNP substrate deposited at 300 °C exhibits a higher intensity as compared with that of BSA adsorbed on the SERS active substrates at any other T s.

  16. The effect of strain induced by Ag underlayer on saturation magnetization of partially ordered Fe16N2 thin films

    DOE PAGES

    Yang, Meiyin; Allard, Lawrence F.; Ji, Nian; Zhang, Xiaowei; Yu, Guang-Hua; Wang, Jian -Ping

    2013-12-12

    Small angle neutron scattering (SANS) and scanning transmission electron microscopy (STEM) were used to study film formation by magnesium alloys AZ31B (Mg-3Al-1Zn base) and ZE10A (Elektron®717, E717: Mg-1Zn + Nd, Zr) in H2O and D2O with and without 1 or 5 wt.% NaCl. No SANS scattering changes were observed after 24 h D2O or H2O exposures compared with as received (unreacted) alloy, consistent with relatively dense MgO-base film formation. However, exposure to 5 wt.% NaCl resulted in accelerated corrosion, with resultant SANS scattering changes detected. The SANS data indicated both particle and rough surface (internal and external) scattering, but withmore » no preferential size features. The films formed in 5 wt.% NaCl consisted of a thin, inner MgO-base layer, and a nano-porous and filamentous Mg(OH)2 outer region tens of microns thick. Chlorine was detected extending to the inner MgO-base film region, with segregation of select alloying elements also observed in the inner MgO, but not the outer Mg(OH)2. Modeling of the SANS data suggested that the outer Mg(OH)2 films had very high surface areas, consistent with loss of film protectiveness. Here, implications for the NaCl corrosion mechanism, and the potential utility of SANS for Mg corrosion, are discussed.« less

  17. A comparative study of the effects of Ag2S films prepared by MPD and HRTD methods on the performance of polymer solar cells

    NASA Astrophysics Data System (ADS)

    Zhai, Yong; Li, Fumin; Ling, Lanyun; Chen, Chong

    2016-10-01

    In this work, the Ag2S nanocrystalline thin films are deposited on ITO glass via molecular precursor decomposition (MPD) method and newly developed HRTD method for organic solar cells (ITO/Ag2S/P3HT:PCBM/MoO3/Au) as an electron selective layer and a light absorption material. The surface morphology, structure characterization, and optical property of the Ag2S films prepared by these two methods were compared and the effect of the prepared Ag2S film on the device performance is investigated. It is found that the Ag2S films prepared by HRTD method have lower roughness and better uniformity than the corresponding films prepared by the MPD method. In addition, a more effective and rapid transporting ability for the electrons and holes in the ITO/Ag2S(HRTD, n)/P3HT:PCBM/MoO3/Au cells is found, which reduces the charge recombination, and thus, improves the device performance. The highest efficiency of 3.21% achieved for the ITO/Ag2S(HRTD, 50)/P3HT:PCBM/MoO3/Au cell is 93% higher than that of the ITO/Ag2S(MPD, 2)/P3HT:PCBM/MoO3/Au cell.

  18. Exposure-dependent Ag+ release from silver nanoparticles and its complexation in AgS2 sites in primary murine macrophages

    NASA Astrophysics Data System (ADS)

    Veronesi, G.; Aude-Garcia, C.; Kieffer, I.; Gallon, T.; Delangle, P.; Herlin-Boime, N.; Rabilloud, T.; Carrière, M.

    2015-04-01

    Silver nanoparticle (AgNP) toxicity is related to their dissolution in biological environments and to the binding of the released Ag+ ions in cellulo; the chemical environment of recombined Ag+ ions is responsible for their toxicological outcome, moreover it is indicative of the cellular response to AgNP exposure, and can therefore shed light on the mechanisms governing AgNP toxicity. This study probes the chemistry of Ag species in primary murine macrophages exposed to AgNPs by making use of X-ray Absorption Fine Structure spectroscopy under cryogenic conditions: the linear combination analysis of the near-edge region of the spectra provides the fraction of Ag+ ions released from the AgNPs under a given exposure condition and highlights their complexation with thiolate groups; the ab initio modelling of the extended spectra allows measuring the Ag-S bond length in cellulo. Dissolution rates depend on the exposure scenario, chronicity leading to higher Ag+ release than acute exposure; Ag-S bond lengths are 2.41 +/- 0.03 Å and 2.38 +/- 0.01 Å in acute and chronic exposure respectively, compatible with digonal AgS2 coordination. Glutathione is identified as the most likely putative ligand for Ag+. The proposed method offers a scope for the investigation of metallic nanoparticle dissolution and recombination in cellular models.Silver nanoparticle (AgNP) toxicity is related to their dissolution in biological environments and to the binding of the released Ag+ ions in cellulo; the chemical environment of recombined Ag+ ions is responsible for their toxicological outcome, moreover it is indicative of the cellular response to AgNP exposure, and can therefore shed light on the mechanisms governing AgNP toxicity. This study probes the chemistry of Ag species in primary murine macrophages exposed to AgNPs by making use of X-ray Absorption Fine Structure spectroscopy under cryogenic conditions: the linear combination analysis of the near-edge region of the spectra provides

  19. NpCoGe, near quantum criticality?

    NASA Astrophysics Data System (ADS)

    Colineau, E.; Eloirdi, R.; Griveau, J.-C.; Gaczynski, P.; Shick, A. B.

    2013-05-01

    The magnetic and electronic properties of NpCoGe are reported. NpCoGe orders antiferromagnetically at T N ≈ 13 K with an average ordered magnetic moment < µ N p > = 0.80 µ B . The comparison with NpRhGe and uranium analogues suggests the leading role of f-d hybridization, the rather delocalized character of 5f electrons in NpCoGe and its possible proximity to a magnetic quantum critical point.

  20. In situ formation of silver nanoparticles on thin-film composite reverse osmosis membranes for biofouling mitigation.

    PubMed

    Ben-Sasson, Moshe; Lu, Xinglin; Bar-Zeev, Edo; Zodrow, Katherine R; Nejati, Siamak; Qi, Genggeng; Giannelis, Emmanuel P; Elimelech, Menachem

    2014-10-01

    The potential to incorporate silver nanoparticles (Ag-NPs) as biocides in membranes for water purification has gained much interest in recent years. However, a viable strategy for loading the Ag-NPs on the membrane remains challenging. This paper presents a novel, facile procedure for loading Ag-NPs on thin-film composite (TFC) reverse osmosis membranes. Reaction of silver salt with a reducing agent on the membrane surface resulted in uniform coverage of Ag-NPs, irreversibly bound to the membrane, as confirmed by XPS, TEM, and SEM analyses. Salt selectivity of the membrane as well its surface roughness, hydrophilicity, and zeta potential were not impacted by Ag-NP functionalization, while a slight reduction (up to 17%) in water permeability was observed. The formed Ag-NPs imparted strong antibacterial activity to the membrane, leading to reduction of more than 75% in the number of live bacteria attached to the membrane for three model bacteria strains. In addition, confocal microscopy analyses revealed that Ag-NPs significantly suppressed biofilm formation, with 41% reduction in total biovolume and significant reduction in EPS, dead, and live bacteria on the functionalized membrane. The simplicity of the method, the short reaction time, the ability to load the Ag-NPs on site, and the strong imparted antibacterial activity highlight the potential of this method in real-world RO membrane applications.

  1. Enhanced magnetic and bolometric sensitivity of La{sub 0.7}Ce{sub 0.3}MnO{sub 3} thin films due to 200 MeV Ag ion irradiation

    SciTech Connect

    Choudhary, R.J.; Kumar, Ravi; Patil, S.I.; Husain, Shahid; Srivastava, J.P.; Malik, S.K.

    2005-05-30

    The parameters for bolometric performance [temperature coefficient of resistance (TCR) and noise value] and magnetic sensitivity of pulsed-laser-deposited thin films of La{sub 0.7}Ce{sub 0.3}MnO{sub 3} and their dependence on the 200 MeV Ag ions irradiation are studied. It is observed that the TCR value and magnetic sensitivity can be tuned in different temperature regime by controlling the irradiation fluence value. It turns out that irradiation with a fluence value of 5x10{sup 10} ions/cm{sup 2} changes the TCR value in a positive direction and enhances magnetic sensitivity at room temperature, while irradiation with a fluence value of 1x10{sup 12} ions/cm{sup 2} enhances these parameters at 200 K. The observations are explained on the basis of structural and electrical transport modifications induced by the 200 MeV Ag ion irradiation.

  2. Structural, electrical transport, magnetization, and 1/f noise studies in 200 MeV Ag ion irradiated La{sub 0.7}Ce{sub 0.3}MnO{sub 3} thin films

    SciTech Connect

    Kumar, Ravi; Choudhary, R.J.; Patil, S.I.; Husain, Shahid; Srivastava, J.P.; Sanyal, S.P.; Lofland, S.E.

    2004-12-15

    The effect of 200 MeV Ag ion irradiation on structural, electrical transport, magnetization, and low-frequency conduction noise properties of electron-doped La{sub 0.7}Ce{sub 0.3}MnO{sub 3} thin films have been investigated. The as-grown thin films show c-axis epitaxial structure along with a small amount of unreacted CeO{sub 2} phase. After the irradiation, at the lowest fluence both the magnetization and metal-insulator transition temperature increase. Further increase in fluence reduces the metal-insulator transition temperature and leads to larger resistivity; however, the unreacted phase of CeO{sub 2} disappears in the x-ray diffraction pattern. On the other hand, the normalized electrical noise is greatly enhanced even at the lowest nonzero fluence. Surprisingly the conducting noise in the irradiated samples is much higher in the metallic state than in the semiconducting one. The observed modifications in structural, electrical, magnetic, and noise properties of 200 MeV Ag ion irradiated La{sub 0.7}Ce{sub 0.3}MnO{sub 3} thin films have been explained on the basis of effects of the presence of swift heavy-ion irradiation-induced strain and defects.

  3. Understanding and Interpreting Japanese NP1 "wa" NP2 "da" Sentences: Mechanism and Contextual Factors

    ERIC Educational Resources Information Center

    Yoshida, Megumi

    2013-01-01

    This dissertation investigates the contextual factors that affect the understanding and interpretation of one Japanese topicalized construction, NP[subscript 1] wa NP[subscript 2] da sentences, by native speakers of Japanese. The construction allows two possibilities in the relation between the NP[subscript 1] and the NP[subscript 2]. When the two…

  4. Sorption of Np by UO2 under repository conditions

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  5. Toxicokinetics of Ag in the terrestrial isopod Porcellionides pruinosus exposed to Ag NPs and AgNO₃ via soil and food.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Morgan, A John; Kille, Peter; Svendsen, Claus; Jurkschat, Kerstin; Mosselmans, J Fred W; Soares, Amadeu M V M; Loureiro, Susana

    2016-03-01

    Silver nanoparticles (Ag NPs) have been used in numerous consumer products and may enter the soil through the land application of biosolids. However, little is known about the relationship between Ag NP exposure and their bioavailability for soil organisms. This study aims at comparing the uptake and elimination kinetics of Ag upon exposures to different Ag forms (NPs and ionic Ag (as AgNO3)) in the isopod Porcellionides pruinosus. Isopods were exposed to contaminated Lufa 2.2 soil or alder leaves as food. Uptake and elimination rate constants for soil exposure did not significantly differ between Ag NPs and ionic Ag at 30 and 60 mg Ag/kg. For dietary exposure, the uptake rate constant was up to 5 times higher for Ag NPs than for AgNO3, but this was related to feeding activity and exposure concentrations, while no difference in the elimination rate constants was found. When comparing both routes, dietary exposure resulted in lower Ag uptake rate constants but elimination rate constants did not differ. A fast Ag uptake was observed from both routes and most of the Ag taken up seemed not to be eliminated. Synchrotron X-ray fluorescence showed Ag in the S-cells of the hepatopancreas, thus supporting the observations from the kinetic experiment (i.e. low elimination). In addition, our results show that isopods have an extremely high Ag accumulation capacity, suggesting the presence of an efficient Ag storage compartment. PMID:26581474

  6. Toxicokinetics of Ag in the terrestrial isopod Porcellionides pruinosus exposed to Ag NPs and AgNO₃ via soil and food.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Morgan, A John; Kille, Peter; Svendsen, Claus; Jurkschat, Kerstin; Mosselmans, J Fred W; Soares, Amadeu M V M; Loureiro, Susana

    2016-03-01

    Silver nanoparticles (Ag NPs) have been used in numerous consumer products and may enter the soil through the land application of biosolids. However, little is known about the relationship between Ag NP exposure and their bioavailability for soil organisms. This study aims at comparing the uptake and elimination kinetics of Ag upon exposures to different Ag forms (NPs and ionic Ag (as AgNO3)) in the isopod Porcellionides pruinosus. Isopods were exposed to contaminated Lufa 2.2 soil or alder leaves as food. Uptake and elimination rate constants for soil exposure did not significantly differ between Ag NPs and ionic Ag at 30 and 60 mg Ag/kg. For dietary exposure, the uptake rate constant was up to 5 times higher for Ag NPs than for AgNO3, but this was related to feeding activity and exposure concentrations, while no difference in the elimination rate constants was found. When comparing both routes, dietary exposure resulted in lower Ag uptake rate constants but elimination rate constants did not differ. A fast Ag uptake was observed from both routes and most of the Ag taken up seemed not to be eliminated. Synchrotron X-ray fluorescence showed Ag in the S-cells of the hepatopancreas, thus supporting the observations from the kinetic experiment (i.e. low elimination). In addition, our results show that isopods have an extremely high Ag accumulation capacity, suggesting the presence of an efficient Ag storage compartment.

  7. Effect of wettability on surface morphologies and optical properties of Ag thin films grown on glass and polymer substrates by thermal evaporation

    NASA Astrophysics Data System (ADS)

    Lv, Jing

    2013-05-01

    A series of Ag films with different thicknesses were deposited on BK-7 glass, PET and PC substrates under identical conditions by thermal evaporation. The effect of the wettability on the morphology and optical properties of Ag/glass and Ag/polymer films was studied by atomic force microscopy and spectrophotometry. The experimental results show that the wettability of Ag grains with polymer is stronger than with glass, which results in the aggregation of bigger grains in initial layer. During deposition the interaction of interlayer plays an important role for the formation of the surface morphology. The strong wettability activates the nonlinear optical properties of Ag grains grown on polymer substrates, which result in the strong absorbance in short wavelength. The effect of the bare substrate on the transmittance of Ag films is more obvious than the reflectance. With the increasing of the thickness, the effect of the wettability on the morphology and optical properties of Ag films decline. In this experiment when the thickness is above 50 nm, the effect almost vanished.

  8. Structural development of gold and silver nanoparticles within hexagonally ordered spherical micellar diblock copolymer thin films

    NASA Astrophysics Data System (ADS)

    Chen, Chia-Min; Huang, Yi-Jiun; Wei, Kung-Hwa

    2014-05-01

    The spatial arrangement of metal nanoparticle (NP) arrays in block copolymers has many potential applications in OFET-type memory devices. In this study, we adopted a trapping approach in which we used a monolayer thin film of polystyrene-block-poly(4-vinylpyridine) (PS56k-b-P4VP8k)--a highly asymmetric diblock copolymer having a spherical micelle morphology--to incorporate various amounts of one-phase-synthesized dodecanethiol-passivated silver (DT-Ag) NPs and a fixed amount of ligand-exchanged pyridine-coated gold (Py-Au) NPs into the polystyrene (PS) and poly(4-vinylpyridine) (P4VP) blocks, respectively. We characterized the packing of these metal NPs in the two blocks of the nanostructured diblock copolymer using reciprocal-space synchrotron grazing incidence small-angle X-ray scattering (GISAXS) as well as atomic force microscopy (AFM) and transmission electron microscopy (TEM) in the real space. The packing of the Ag NPs in the PS block was dependent on their content, which we tuned by varying the concentrations in the composite solution at a constant rate of spin-coating. The two-dimensional hierarchical arrangement of Ag and Au NPs within the BCP thin films was enhanced after addition of the Py-Au NPs into the P4VP block and after spin-coating a thinner film from a low concentration solution (0.1 wt%), due to the DT-Ag NPs accumulating around the Py-Au/P4VP cores; this two-dimensional hierarchical arrangement decreased at a critical DT-Ag NP weight ratio (c) of 0.8 when incorporating the Py-Au NPs into the P4VP domains through spin-coating at higher solution concentration (0.5 wt%), where the DT-Ag NPs realigned by rotating 20° along the z axis in the real space, due to oversaturation of the DT-Ag NPs within the PS domains.The spatial arrangement of metal nanoparticle (NP) arrays in block copolymers has many potential applications in OFET-type memory devices. In this study, we adopted a trapping approach in which we used a monolayer thin film of

  9. Study on single-domain growth of Y1.8Ba2.4Cu3.4Oy/Ag system by using Nd123/MgO thin film as seed

    NASA Astrophysics Data System (ADS)

    Cai, C.; Tachibana, K.; Fujimoto, H.

    2000-06-01

    Instead of NdBa2Cu3Oy (Nd123) bulk crystal, a (001) Nd123/MgO thin film is used as the seed to study single-domain growth in the isothermal solidification of the YBaCuO/Ag system. Various maximum processing temperatures (Tmax), down to 1000 °C, are used to fabricate the textured domain. The dependences of nucleation and single-domain growth on undercooling and Tmax are studied, respectively. For the lower Tmax processed sample, non-steady growth takes place after a time interval, which is attributed to random nucleation.

  10. Ising formulations of many NP problems

    NASA Astrophysics Data System (ADS)

    Lucas, Andrew

    2014-02-01

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

  11. Syntheses, Structures, and Magnetic Properties of Np3S5 and Np3Se5

    SciTech Connect

    Jin, Geng Bang; Skanthakumar, S; Haire, Richard {Dick} G; Soderholm, L; Ibers, James A.

    2010-01-01

    Black prisms of Np3Q5 (Q = S, Se) have been synthesized by the stoichiometric reactions between Np and Q at 1173 K in a CsCl flux. The structures of these compounds were characterized by single-crystal X-ray diffraction methods. The Np3Q5 compounds are isostructural with U3Q5. The structure of Np3Q5 is constructed from layers of Np(1)Q8 distorted bicapped trigonal prisms that share faces with each other on bc planes. Each Np(1)Q8 layer further shares Q(2) edges with two adjacent identical neighbors to form a three-dimensional framework. The space inside each channel within this framework is filled by one single edge-sharing Np(2)Q7 distorted 7-octahedron chain running along the b axis. Magnetic susceptibility measurements show that Np3S5 and Np3Se5 have antiferromagnetic orderings at 35(1) and 36(1) K, respectively. Above the magnetic ordering temperatures, both Np3S5 and Np3Se5 behave as typical Curie-Weiss paramagnets. The effective moments obtained from the fit of the magnetic data to a modified Curie- Weiss law over the temperature range 70 to 300 K are 2.7(2) B (Np3S5) and 2.9(2) B (Np3Se5).

  12. (237)Np Mössbauer effect study on NpFeAsO.

    PubMed

    Gaczyński, P; Klimczuk, T; Walker, H; Springell, R; Colineau, E; Eloirdi, R; Griveau, J-C; Caciuffo, R

    2014-04-16

    We report (237)Np Mössbauer measurements on NpFeAsO. The Np atoms were found to occupy only one crystallographic site. The value of the isomer shift (δ ∼ 9.1 mm s(-1) versus NpAl2) indicates a 5f(4) electronic configuration (Np(3+) ions). The magnetic ordering of the Np sublattice below 60 K is established and the saturated ordered magnetic moment is determined to be 1.73μB at 3.6 K. The unique set of hyperfine parameters exclude a modulated magnetic structure or spin waves on the Np site. The neptunium magnetic moments μNp are found to lie along the tetragonal c-axis.

  13. Transport of silver nanoparticles (AgNPs) in soil.

    PubMed

    Sagee, Omer; Dror, Ishai; Berkowitz, Brian

    2012-07-01

    The effect of soil properties on the transport of silver nanoparticles (AgNPs) was studied in a set of laboratory column experiments, using different combinations of size fractions of a Mediterranean sandy clay soil. The AgNPs with average size of ~30nm yielded a stable suspension in water with zeta potential of -39mV. Early breakthrough of AgNPs in soil was observed in column transport experiments. AgNPs were found to have high mobility in soil with outlet relative concentrations ranging from 30% to 70%, depending on experimental conditions. AgNP mobility through the column decreased when the fraction of smaller soil aggregates was larger. The early breakthrough pattern was not observed for AgNPs in pure quartz columns nor for bromide tracer in soil columns, suggesting that early breakthrough is related to the nature of AgNP transport in natural soils. Micro-CT and image analysis used to investigate structural features of the soil, suggest that soil aggregate size strongly affects AgNP transport in natural soil. The retention of AgNPs in the soil column was reduced when humic acid was added to the leaching solution, while a lower flow rate (Darcy velocity of 0.17cm/min versus 0.66cm/min) resulted in higher retention of AgNPs in the soil. When soil residual chloride was exchanged by nitrate prior to column experiments, significantly improved mobility of AgNPs was observed in the soil column. These findings point to the importance of AgNP-soil chemical interactions as a retention mechanism, and demonstrate the need to employ natural soils rather than glass beads or quartz in representative experimental investigations.

  14. Enhancement of magnetoresistance by inserting thin NiAl layers at the interfaces in Co2FeGa0.5Ge0.5/Ag/Co2FeGa0.5Ge0.5 current-perpendicular-to-plane pseudo spin valves

    NASA Astrophysics Data System (ADS)

    Jung, J. W.; Sakuraba, Y.; Sasaki, T. T.; Miura, Y.; Hono, K.

    2016-03-01

    We have investigated the effects of insertion of a thin NiAl layer (≤0.63 nm) into a Co2FeGa0.5Ge0.5 (CFGG)/Ag interface on the magnetoresistive properties in CFGG/Ag/CFGG current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo spin valves (PSVs). First-principles calculations of ballistic transmittance clarified that the interfacial band matching at the (001)-oriented NiAl/CFGG interface is better than that at the (001)-Ag/CFGG interface. The insertion of 0.21-nm-thick NiAl layers at the Co2FeGa0.5Ge0.5/Ag interfaces effectively improved the magnetoresistance (MR) output; the observed average and the highest MR ratio (ΔRA) are 62% (25 mΩ μm2) and 77% (31 mΩ μm2) at room temperature, respectively, which are much higher than those without NiAl insertion. Microstructural analysis using scanning transmission electron microscopy confirmed the existence of thin NiAl layers at the Ag interfaces with only modest interdiffusion even after annealing at 550 °C. The improvement of the interfacial spin-dependent scattering by very thin NiAl insertion can be a predominant reason for the enhancement of the MR output.

  15. Ion-modulated nonlinear electronic transport in carbon nanotube bundle/RbAg{sub 4}I{sub 5} thin film composite nanostructures

    SciTech Connect

    Sun, Jia-Lin; Zhang, Wei; Wei, Jinquan; Gu, Bingfu

    2014-01-28

    We have explored the ion-modulated electronic transport properties of mixed ionic-electronic conductor (MIEC) composite nanostructures made of superionic conductor RbAg{sub 4}I{sub 5} films and carbon nanotube (CNT) bundle spiderwebs. Our experimental and theoretical studies indicate that the formation of ion-electron bound states (IEBSs) leads to strong ion-electron interference effect and interesting electronic transport of CNT, such as nonlinear current-voltage (I–V) characteristics and novel temperature dependence of the current. With increasing temperature, the hybrid nanostructures show rich phases with different dependence of current on temperature, which is related to the structural phase transition of RbAg{sub 4}I{sub 5} and the transition of dissociation of IEBSs. The ion-modulation of the electric conductivity in such MIEC composite nanostructures with great tunability has been used to design new ionic-electronic composite nano-devices with function like field effect transistor.

  16. Photoelectrochemical decomposition of water into H2 and O2 on porous BiVO4 thin-film electrodes under visible light and significant effect of Ag ion treatment.

    PubMed

    Sayama, Kazuhiro; Nomura, Atsushi; Arai, Takeo; Sugita, Tsuyoshi; Abe, Ryu; Yanagida, Masatoshi; Oi, Takashi; Iwasaki, Yasukazu; Abe, Yoshimoto; Sugihara, Hideki

    2006-06-15

    The photoelectrochemical properties of porous BiVO4 thin-film electrodes on conducting glass for H2 production from water under visible light were investigated. BiVO4 films were prepared by the metal-organic decomposition method, and particles were 90-150 nm in diameter. Under visible-light irradiation, H2 and O2 evolved in a stoichiometric ratio (H2/O2 = 2) from an aqueous solution of Na2SO4 with an external bias. The photocurrent increased with addition of methanol. The band structure of BiVO4 was investigated by open-circuit potential, flat-band potential, X-ray photoelectron spectroscopy, and calculations based on density functional theory. The top of the valence-band potential of BiVO4 was shifted negatively compared to the potentials of the conventional oxide semiconductors without Bi. We surmise that hybridization between the O-2p and Bi-6s orbitals might contribute to the negative shift of the BiVO4 valence band. Treatment with an aqueous solution of AgNO3 improved the photocurrent of the BiVO4 electrode significantly. The maximum incident photon-to-current conversion efficiency at 420 nm was 44%. This value was the highest among mixed-oxide semiconductor electrodes under visible light irradiation. AgNO3 treatment also improved the stability of the photocurrent. The Ag+ ion in/on the BiVO4 catalyzed the intrinsic photogeneration of oxygen with the holes.

  17. Criticality of a {sup 237}Np Sphere

    SciTech Connect

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

    2003-07-22

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

  18. Nuclear resonance fluorescence of Np237

    NASA Astrophysics Data System (ADS)

    Angell, C. T.; Yee, R.; Joshi, T. H.; Swanberg, E.; Norman, E. B.; Hicks, C. L., Jr.; Klimenko, A.; Korbly, S.; Wilson, C.; Kulp, W. D.; Warren, G. A.; Bray, T. H.; Copping, R.; Glans, P. A.; Tyliszczak, T.; Shuh, D. K.

    2010-11-01

    Measurements of states excited by nuclear resonance fluorescence in Np237 were performed using a bremsstrahlung beam. Fifteen new states were observed in the region of 1.7 to 2.5 MeV. They can be used to detect or assay Np237 nondestructively for applications in security and safeguards. The states are populated with similar strength as those states found previously in U235 and Pu239 but are spread out more in energy.

  19. Nuclear resonance fluorescence of {sup 237}Np

    SciTech Connect

    Angell, C. T.; Yee, R.; Joshi, T. H.; Swanberg, E.; Norman, E. B.; Hicks, C. L. Jr.; Klimenko, A.; Korbly, S.; Wilson, C.; Kulp, W. D.; Warren, G. A.; Bray, T. H.; Copping, R.; Glans, P. A.; Tyliszczak, T.; Shuh, D. K.

    2010-11-15

    Measurements of states excited by nuclear resonance fluorescence in {sup 237}Np were performed using a bremsstrahlung beam. Fifteen new states were observed in the region of 1.7 to 2.5 MeV. They can be used to detect or assay {sup 237}Np nondestructively for applications in security and safeguards. The states are populated with similar strength as those states found previously in {sup 235}U and {sup 239}Pu but are spread out more in energy.

  20. Impact of Ag nanoparticle exposure on p,p'-DDE bioaccumulation by Cucurbita pepo (zucchini) and Glycine max (soybean).

    PubMed

    De La Torre-Roche, Roberto; Hawthorne, Joseph; Musante, Craig; Xing, Baoshan; Newman, Lee A; Ma, Xingmao; White, Jason C

    2013-01-15

    The effect of nanoparticle (NP), bulk, or ionic Ag exposure on dichlorodiphenyldichloroethylene (p,p'-DDE; DDT metabolite) accumulation by Glycine max L. (soybean) and Cucurbita pepo L. (zucchini) was investigated. The plants were grown in 125-mL jars of vermiculite amended with 500 or 2000 mg/L of bulk or NP Ag; ion controls at 5 and 20 mg/L were established. During 19 d of growth, plants were amended with solution containing 100 ng/mL of p,p'-DDE. Total shoot p,p'-DDE levels in non-Ag exposed G. max and C. pepo were 500 and 970 ng, respectively; total root DDE content was 13,700 and 20,300 ng, respectively. Ag decreased the p,p'-DDE content of G. max tissues by up to 40%, with NP exposure resulting in less contaminant uptake than bulk Ag. Total Ag content of exposed G. max ranged from 50.5 to 373 μg; NP-exposed plants had 1.9-2.2 times greater overall Ag than corresponding bulk particle treatments and also significantly greater relative Ag transport to shoot tissues. Bulk and NP Ag at 500 mg/L suppressed DDE uptake by C. pepo by 21-29%, although Ag exposure at 2000 mg/L had no impact on contaminant uptake. Similar to G. max , C. pepo whole plant Ag content ranged from 50.5 to 182 μg, with tissue element content generally being greater for NP exposed plants. These findings show that the Ag may significantly alter the accumulation and translocation of cocontaminants in agricultural systems. Notably, the cocontaminant interactions vary both with Ag particle size (NP vs bulk) and plant species. Future investigations will be needed to clarify the mechanisms responsible for the cocontaminant interactions and assess the impact on overall exposure and risk.

  1. SERS activity of Ag decorated nanodiamond and nano-β-SiC, diamond-like-carbon and thermally annealed diamond thin film surfaces.

    PubMed

    Kuntumalla, Mohan Kumar; Srikanth, Vadali Venkata Satya Siva; Ravulapalli, Satyavathi; Gangadharini, Upender; Ojha, Harish; Desai, Narayana Rao; Bansal, Chandrahas

    2015-09-01

    In the recent past surface enhanced Raman scattering (SERS) based bio-sensing has gained prominence owing to the simplicity and efficiency of the SERS technique. Dedicated and continuous research efforts have been made to develop SERS substrates that are not only stable, durable and reproducible but also facilitate real-time bio-sensing. In this context diamond, β-SiC and diamond-like-carbon (DLC) and other related thin films have been promoted as excellent candidates for bio-technological applications including real time bio-sensing. In this work, SERS activities of nanodiamond, nano-β-SiC, DLC, thermally annealed diamond thin film surfaces were examined. DLC and thermally annealed diamond thin films were found to show SERS activity without any metal nanostructures on their surfaces. The observed SERS activities of the considered surfaces are explained in terms of the electromagnetic enhancement mechanism and charge transfer resonance process. PMID:25691097

  2. SERS activity of Ag decorated nanodiamond and nano-β-SiC, diamond-like-carbon and thermally annealed diamond thin film surfaces.

    PubMed

    Kuntumalla, Mohan Kumar; Srikanth, Vadali Venkata Satya Siva; Ravulapalli, Satyavathi; Gangadharini, Upender; Ojha, Harish; Desai, Narayana Rao; Bansal, Chandrahas

    2015-09-01

    In the recent past surface enhanced Raman scattering (SERS) based bio-sensing has gained prominence owing to the simplicity and efficiency of the SERS technique. Dedicated and continuous research efforts have been made to develop SERS substrates that are not only stable, durable and reproducible but also facilitate real-time bio-sensing. In this context diamond, β-SiC and diamond-like-carbon (DLC) and other related thin films have been promoted as excellent candidates for bio-technological applications including real time bio-sensing. In this work, SERS activities of nanodiamond, nano-β-SiC, DLC, thermally annealed diamond thin film surfaces were examined. DLC and thermally annealed diamond thin films were found to show SERS activity without any metal nanostructures on their surfaces. The observed SERS activities of the considered surfaces are explained in terms of the electromagnetic enhancement mechanism and charge transfer resonance process.

  3. Influence of size, shape and core-shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiO x.

    PubMed

    D'Addato, Sergio; Pinotti, Daniele; Spadaro, Maria Chiara; Paolicelli, Guido; Grillo, Vincenzo; Valeri, Sergio; Pasquali, Luca; Bergamini, Luca; Corni, Stefano

    2015-01-01

    Ag and Ag@MgO core-shell nanoparticles (NPs) with a diameter of d = 3-10 nm were obtained by physical synthesis methods and deposited on Si with its native ultrathin oxide layer SiO x (Si/SiO x ). Scanning electron microscopy and transmission electron microscopy (TEM) images of bare Ag NPs revealed the presence of small NP aggregates caused by diffusion on the surface and agglomeration. Atomic resolution TEM gave evidence of the presence of crystalline multidomains in the NPs, which were due to aggregation and multitwinning occurring during NP growth in the nanocluster source. Co-deposition of Ag NPs and Mg atoms in an oxygen atmosphere gave rise to formation of a MgO shell matrix surrounding the Ag NPs. The behaviour of the surface plasmon resonance (SPR) excitation in surface differential reflectivity (SDR) spectra with p-polarised light was investigated for bare Ag and Ag@MgO NPs. It was shown that the presence of MgO around the Ag NPs caused a red shift of the plasmon excitation, and served to preserve its existence after prolonged (five months) exposure to air, realizing the possibility of technological applications in plasmonic devices. The Ag NP and Ag@MgO NP film features in the SDR spectra could be reproduced by classical electrodynamics simulations by treating the NP-containing layer as an effective Maxwell Garnett medium. The simulations gave results in agreement with the experiments when accounting for the experimentally observed aggregation.

  4. In situ study of defect migration kinetics in nanoporous Ag with enhanced radiation tolerance

    PubMed Central

    Sun, C.; Bufford, D.; Chen, Y.; Kirk, M. A.; Wang, Y. Q.; Li, M.; Wang, H.; Maloy, S. A.; Zhang, X.

    2014-01-01

    Defect sinks, such as grain boundaries and phase boundaries, have been widely accepted to improve the irradiation resistance of metallic materials. However, free surface, an ideal defect sink, has received little attention in bulk materials as surface-to-volume ratio is typically low. Here by using in situ Kr ion irradiation technique in a transmission electron microscope, we show that nanoporous (NP) Ag has enhanced radiation tolerance. Besides direct evidence of free surface induced frequent removal of various types of defect clusters, we determined, for the first time, the global and instantaneous diffusivity of defect clusters in both coarse-grained (CG) and NP Ag. Opposite to conventional wisdom, both types of diffusivities are lower in NP Ag. Such a surprise is largely related to the reduced interaction energy between isolated defect clusters in NP Ag. Determination of kinetics of defect clusters is essential to understand and model their migration and clustering in irradiated materials. PMID:24435181

  5. Structural development of gold and silver nanoparticles within hexagonally ordered spherical micellar diblock copolymer thin films.

    PubMed

    Chen, Chia-Min; Huang, Yi-Jiun; Wei, Kung-Hwa

    2014-06-01

    The spatial arrangement of metal nanoparticle (NP) arrays in block copolymers has many potential applications in OFET-type memory devices. In this study, we adopted a trapping approach in which we used a monolayer thin film of polystyrene-block-poly(4-vinylpyridine) (PS56k-b-P4VP8k)-a highly asymmetric diblock copolymer having a spherical micelle morphology-to incorporate various amounts of one-phase-synthesized dodecanethiol-passivated silver (DT-Ag) NPs and a fixed amount of ligand-exchanged pyridine-coated gold (Py-Au) NPs into the polystyrene (PS) and poly(4-vinylpyridine) (P4VP) blocks, respectively. We characterized the packing of these metal NPs in the two blocks of the nanostructured diblock copolymer using reciprocal-space synchrotron grazing incidence small-angle X-ray scattering (GISAXS) as well as atomic force microscopy (AFM) and transmission electron microscopy (TEM) in the real space. The packing of the Ag NPs in the PS block was dependent on their content, which we tuned by varying the concentrations in the composite solution at a constant rate of spin-coating. The two-dimensional hierarchical arrangement of Ag and Au NPs within the BCP thin films was enhanced after addition of the Py-Au NPs into the P4VP block and after spin-coating a thinner film from a low concentration solution (0.1 wt%), due to the DT-Ag NPs accumulating around the Py-Au/P4VP cores; this two-dimensional hierarchical arrangement decreased at a critical DT-Ag NP weight ratio (c) of 0.8 when incorporating the Py-Au NPs into the P4VP domains through spin-coating at higher solution concentration (0.5 wt%), where the DT-Ag NPs realigned by rotating 20° along the z axis in the real space, due to oversaturation of the DT-Ag NPs within the PS domains.

  6. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum

    NASA Astrophysics Data System (ADS)

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-01

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10-5 Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  7. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum

    NASA Astrophysics Data System (ADS)

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-01

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10‑5 Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  8. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum.

    PubMed

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-16

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10(-5) Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

  9. Noble-metal Ag nanoparticle chains: annealing Ag/Bi superlattice nanowires in vacuum.

    PubMed

    Xu, Shao Hui; Fei, Guang Tao; You, Qiao; Gao, Xu Dong; Huo, Peng Cheng; De Zhang, Li

    2016-09-16

    One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10(-5) Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains. PMID:27487089

  10. LITERATURE REVIEW: REDUCTION OF NP(V) TO NP (IV)-ALTERNATIVES TO FERROUS SULFAMATE

    SciTech Connect

    Kessinger, G.; Kyser, E.; Almond, P.

    2009-09-28

    The baseline approach to control of Np oxidation in UREX and PUREX separation processes is the reduction of Np(V) and Np(VI) to Np(IV) using ferrous sulfamate. Use of this reagent results in increased sulfur and iron concentrations in the liquid waste streams from the process. Presence of these two elements, especially sulfur, increases the complexity of the development of wasteforms for immobilizing these effluents. Investigations are underway to identify reductants that eliminate sulfur and iron from the Np reduction process. While there are a variety of chemical reductants that will reduce Np to Np(IV) in nitric acid media, the reaction rates for most are so slow that the reductants are not be feasible for use in an operating plant process. In an attempt to identify additional alternatives to ferrous sulfamate, a literature search and review was performed. Based on the results of the literature review, it is concluded that photochemical and catalytic processes should also be investigated to test the utility of these two approaches. The catalytic process could be investigated for use in conjunction with chemical oxidants to speed the reaction rates for reductants that react slowly, but would otherwise be appropriate replacements for ferrous sulfamate. The photochemical approach, which has received little attention during the past few decades, also shows promise, especially the photocatalytic approach that includes a catalyst, such as Pt supported on SiC, which can be used in tandem with an oxidant, for Np reduction.

  11. Structural and optical characterization of Ag photo-doped thin As40S60 - xSex films for non-linear applications

    NASA Astrophysics Data System (ADS)

    Tasseva, J.; Todorov, R.; Babeva, Tz; Petkov, K.

    2010-06-01

    This paper deals with the structure and the optical properties of thin As40S60 - xSex films doped with silver. The refractive index n and the optical band gap Egopt were calculated from the transmittance and reflectance spectra. The results showed that the photo-doping leads to increase in the refractive index by about 0.25-0.27. An effect of thickness expansion was observed in the photo-doped layers. The non-linear refractive index, γ, and the two-photon absorption coefficient, β, were evaluated by applying a formula developed by Sheik-Bahae. Each of the films studied exhibits a highly non-linear refractive index at the telecommunication wavelength, 70-850 times higher than that measured for fused silica. From the Raman spectra of thin As40S30Se30 it might be concluded that under dissolution, the silver interacts with both sulfur and selenium. The surface of the thin films was investigated by using a white light interferometric profiler. It was found that the increase in the thickness of the silver layer results in roughening of the surface of the photo-doped films.

  12. NP-MHTGR Fuel Development Program Results

    SciTech Connect

    Maki, John Thomas; Petti, David Andrew; Hobbins, Richard Redfield; McCardell, Richard K.; Shaber, Eric Lee; Southworth, Finis Hio

    2002-10-01

    In August 1988, the Secretary of Energy announced a strategy to acquire New Production Reactor capacity for producing tritium. The strategy involved construction of a New Production Modular High Temperature Gas-Cooled Reactor (NP-MHTGR) where the Idaho National Engineering and Environmental Laboratory (INEEL) was selected as the Management and Operations contractor for the project. Immediately after the announcement in August 1988, tritium target particle development began with the INEEL selected as the lead laboratory. Fuel particle development was initially not considered to be on a critical path for the project, therefore, the fuel development program was to run concurrently with the design effort of the NP-MHTGR.

  13. Autoionizing np Rydberg states of H2

    NASA Astrophysics Data System (ADS)

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

    1989-04-01

    We report a study of the autoionizing np Rydberg states near the lowest ionization threshold of H2. Using resonant two-photon excitation, intermediate states in specific rotovibrational levels in the double well, E,F 1Σ+g states are prepared. Then, a second, tunable laser is used to photoionize via excitation of the np Rydberg states. Because of the stepwise laser excitation scheme employed in our experiment the photoionization occurs from states with vibrational wave functions very similar to those of the H+2 core. As a consequence, the autoionizing states appear as nearly symmetric resonances, rather than the highly asymmetric Beutler-Fano profiles observed from the direct photoexcitation from the ground state of H2. Our experiments show that the J=1 np states are broader than the J=3 np states converging to the same limit, suggesting that the two states autoionize into the ɛp and ɛf continuum, respectively. We compare our observations with a theoretical analysis using a multichannel quantum defect theory. The J=1 states reveal the profound effect caused by the perturbation of the autoionizing Rydberg series converging to the lowest vibrational and rotational state of H+2 by low-n states converging to higher vibrational states of the H2-ion core.

  14. The NP Draconii Multiple Star System

    NASA Astrophysics Data System (ADS)

    Castelaz, Michael W.; Barker, Thurburn; McNaughton, Abby; Robertson, Rachel; Smith, Matt

    2016-01-01

    Otero and Dubovsky used the ASAS-3 (Pojmanski 2002), Hipparcos (Perryman et al 1997) and Northern Sky Variability Survey (NSVS; Wozniak et al 2004) databases to determine elements for 80 eclipsing binaries. NP Draconii (NSV 22984) was identified by Otero and Dubovsky (IBVS Number 5557, 2004) as a possible Algol type variable with an ephemeris of HJD Min I = 2448604.780+3.10886E days based on 84 observations over 326 days with about 2 to 4 observations on any one night. We decided to further refine the ephemeris and observe NP Dra in VRI filters, with the goal of determining the elements of the system.NP Dra is a V = 9.0 system located at J2000 = 17h 35m 16s and +55d 00' 12". We observed NP Dra August 2, 3 and September 15, 16, 17, 18, and 19 2015 UT using the Pisgah Astronomical Research Institute 0.4-m telescope in V, R, and I with 20 second exposure times in each filter. Observations in each filter were repeated about every 3 minutes each night of observing.From our light curves we determined the period using the Date Compensated Discrete Fourier Transform function (Ferraz-Mello 1981) which is part of the open source code VSTAR (AAVSO). The period derived from the observations is 2.2755 days. Superimposed on this period is another period of 0.6398 days. We will present the V, R, and I light curves, period determination and implication

  15. VACTERL with the mitochondrial NP 3243 point mutation

    SciTech Connect

    Damian, M.S.; Dorndorf, W.; Schachenmayr, W.; Seibel, P.; Reichmann, H.

    1996-04-24

    The VACTERL association of vertebral, anal, cardiovascular, tracheo-esophageal, renal, and limb defects is one of the more common congenital disorders with limb deficiency arising during blastogenesis. The cause is probably heterogeneous; a molecular basis has not been defined. We report on a family in which a female infant with VACTERL was born in 1977 and died at age 1 month due to renal failure. Because her mother and sister later developed classical mitochondrial cytopathy associated with the A-G point mutation at nucleotide position (np) 3243 of mitochondrial (mt) DNA, we performed a molecular analysis of mt DNA in preserved kidney tissue from the VACTERL case. We discovered 100% mutant mt DNA in multicystic and 32% mutant mt DNA in normal kidney tissue. Mild deficiency of complex I respiratory chain enzyme activity was found in the mother`s muscle biopsy. Other maternal relatives were healthy but had low levels of mutant mt DNA in blood. This is the first report to provide a precise molecular basis for a case of VACTERL. The differing tissue pathology depending on the percentage of mutant mt DNA suggests a causal connection between the mutation and symptoms. VACTERL, and this type of multicystic renal dysplasia, are new phenotypes for the np 3243 point mutation. The possibility of a mitochondrial disorder should be born in mind and also that VACTERL may occur as a first manifestation of a mutation that has been present for generations. This would have major implications for patient management and for genetic counselling regarding both the risk of recurrence and risk of other mitochondrial syndromes in affected families. 19 refs., 3 figs., 1 tab.

  16. Extracellular Polymeric Substances (EPS) of Freshwater Biofilms Stabilize and Modify CeO2 and Ag Nanoparticles

    PubMed Central

    Kroll, Alexandra; Behra, Renata; Kaegi, Ralf; Sigg, Laura

    2014-01-01

    Streams are potential receiving compartments for engineered nanoparticles (NP). In streams, NP may remain dispersed or settle to the benthic compartment. Both dispersed and settling NP can accumulate in benthic biofilms called periphyton that are essential to stream ecosystems. Periphytic organisms excrete extracellular polymeric substances (EPS) that interact with any material reaching the biofilms. To understand the interaction of NP with periphyton it is therefore crucial to study the interaction of NP with EPS. We investigated the influence of EPS on the physicochemical properties of selected NP (CeO2, Ag) under controlled conditions at pH 6, 7.6, 8.6 and light or dark exposure. We extracted EPS from five different periphyton communities, characterized the extracts, and exposed CeO2 and carbonate-stabilized Ag NP (0.5 and 5 mg/L, both 25 nm primary particle size) and AgNO3 to EPS (10 mg/L) over two weeks. We measured NP size distribution, shape, primary particle size, surface plasmon resonance, and dissolution. All EPS extracts were composed of biopolymers, building blocks of humic substances, low molecular weight (Mr) acids, and small amphiphilic or neutral compounds in varying concentrations. CeO2 NP were stabilized by EPS independent of pH and light/dark while dissolution increased over time in the dark at pH 6. EPS induced a size increase in Ag NP in the light with decreasing pH and the formation of metallic Ag NP from AgNO3 at the same conditions via EPS-enhanced photoreduction. NP transformation and formation were slower in the extract with the lowest biopolymer and low Mr acid concentrations. Periphytic EPS in combination with naturally varying pH and light/dark conditions influence the properties of the Ag and CeO2 NP tested and thus the exposure conditions within biofilms. Our results indicate that periphytic organisms may be exposed to a constantly changing mixture of engineered and naturally formed Ag NP and Ag+. PMID:25333364

  17. Influence of size, shape and core–shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiOx

    PubMed Central

    Pinotti, Daniele; Spadaro, Maria Chiara; Paolicelli, Guido; Grillo, Vincenzo; Valeri, Sergio; Pasquali, Luca; Bergamini, Luca; Corni, Stefano

    2015-01-01

    Summary Ag and Ag@MgO core–shell nanoparticles (NPs) with a diameter of d = 3–10 nm were obtained by physical synthesis methods and deposited on Si with its native ultrathin oxide layer SiOx (Si/SiOx). Scanning electron microscopy and transmission electron microscopy (TEM) images of bare Ag NPs revealed the presence of small NP aggregates caused by diffusion on the surface and agglomeration. Atomic resolution TEM gave evidence of the presence of crystalline multidomains in the NPs, which were due to aggregation and multitwinning occurring during NP growth in the nanocluster source. Co-deposition of Ag NPs and Mg atoms in an oxygen atmosphere gave rise to formation of a MgO shell matrix surrounding the Ag NPs. The behaviour of the surface plasmon resonance (SPR) excitation in surface differential reflectivity (SDR) spectra with p-polarised light was investigated for bare Ag and Ag@MgO NPs. It was shown that the presence of MgO around the Ag NPs caused a red shift of the plasmon excitation, and served to preserve its existence after prolonged (five months) exposure to air, realizing the possibility of technological applications in plasmonic devices. The Ag NP and Ag@MgO NP film features in the SDR spectra could be reproduced by classical electrodynamics simulations by treating the NP-containing layer as an effective Maxwell Garnett medium. The simulations gave results in agreement with the experiments when accounting for the experimentally observed aggregation. PMID:25821680

  18. Understanding the fate and biological effects of Ag- and TiO₂-nanoparticles in the environment: The quest for advanced analytics and interdisciplinary concepts.

    PubMed

    Schaumann, Gabriele E; Philippe, Allan; Bundschuh, Mirco; Metreveli, George; Klitzke, Sondra; Rakcheev, Denis; Grün, Alexandra; Kumahor, Samuel K; Kühn, Melanie; Baumann, Thomas; Lang, Friederike; Manz, Werner; Schulz, Ralf; Vogel, Hans-Jörg

    2015-12-01

    Engineered inorganic nanoparticles (EINP) from consumers' products and industrial applications, especially silver and titanium dioxide nanoparticles (NP), are emitted into the aquatic and terrestrial environments in increasing amounts. However, the current knowledge on their environmental fate and biological effects is diverse and renders reliable predictions complicated. This review critically evaluates existing knowledge on colloidal aging mechanisms, biological functioning and transport of Ag NP and TiO2 NP in water and soil and it discusses challenges for concepts, experimental approaches and analytical methods in order to obtain a comprehensive understanding of the processes linking NP fate and effects. Ag NP undergo dissolution and oxidation with Ag2S as a thermodynamically determined endpoint. Nonetheless, Ag NP also undergo colloidal transformations in the nanoparticulate state and may act as carriers for other substances. Ag NP and TiO2 NP can have adverse biological effects on organisms. Whereas Ag NP reveal higher colloidal stability and mobility, the efficiency of NOM as a stabilizing agent is greater towards TiO2 NP than towards Ag NP, and multivalent cations can dominate the colloidal behavior over NOM. Many of the past analytical obstacles have been overcome just recently. Single particle ICP-MS based methods in combination with field flow fractionation techniques and hydrodynamic chromatography have the potential to fill the gaps currently hampering a comprehensive understanding of fate and effects also at a low field relevant concentrations. These analytical developments will allow for mechanistically orientated research and transfer to a larger set of EINP. This includes separating processes driven by NP specific properties and bulk chemical properties, categorization of effect-triggering pathways directing the EINP effects towards specific recipients, and identification of dominant environmental parameters triggering fate and effect of EINP in

  19. Studies on structural & optical properties of CdS0.2Se0.8: Ag nanocomposite thin film for photosensor application

    NASA Astrophysics Data System (ADS)

    Chaudhari, J. B.; Patil, R. S.; Patil, I. J.; Jagtap, P. P.; Sharma, Ramphal

    2012-06-01

    Silver doped CdS0.2Se0.8 thin films of different concentrations were grown by simple and economical chemical bath deposition technique and later on characterized for optoelectronic and physicochemical properties. The X-ray diffraction (XRD) patterns of undoped and doped sample indicates polycrystalline nature with hexagonal structure. Scanning electron microscopy (SEM) micrograph showed uniform morphology with cabbage type structure for undoped film and leaf-like structure for doped films over the entire glass substrate. Room temperature absorbance for 1 wt% doping concentration of silver showed an excitonic peak which confirms the size quantization of the particle. I-V characteristic for undoped and doped film shows ohmic and Schottky junction behavior.

  20. Facile Decoration of Polyaniline Fiber with Ag Nanoparticles for Recyclable SERS Substrate.

    PubMed

    Mondal, Sanjoy; Rana, Utpal; Malik, Sudip

    2015-05-20

    Facile synthesis of polyaniline@Ag composite has been successfully demonstrated by a simple solution-dipping method using high-aspect-ratio benzene tetracarboxylic acid-doped polyaniline (BDP) fiber as a nontoxic reducing agent as well as template cum stabilizer. In BDP@Ag composite, BDP fibers are decorated with spherical Ag nanoparticles (Ag NPs), and the population of Ag NPs on BDP fibers is controlled by changing the molar concentration of AgNO3. Importantly, Ag-NP-decorated BDP fibers (BDP@Ag composites) have been evolved as a sensitive materials for the detection of trace amounts of 4-mercaptobenzoic acid and rhodamine 6G as an analyte of surface-enhanced Raman scattering (SERS), and the detection limit is down to nanomolar concentrations with excellent recyclability. Furthermore, synthesized BDP@Ag composites are applied simultaneously as an active SERS substrate and a superior catalyst for reduction of 4-nitrothiophenol.

  1. Sorption of Np (V) by U (VI) hydroxide solids

    SciTech Connect

    Wruck, D A; Brachmann, A; Sylwester, E; Allen, C E A

    1999-09-20

    The distribution of {sup 237}Np(V) between aqueous NaHCO{sub 3} solutions and U(VI) hydroxide solids was investigated. Experiments were initiated by addition of U solids to Np solutions and by coprecipitation of U and Np. Analysis by U L{sub III} extended X-ray absorption fine structure (EXAFS) spectroscopy and infrared absorption spectroscopy indicated the solid phase was synthetic schoepite. Equilibrium Np distribution coefficients were 5-44 mL/g in the pH range 6-8. The results are consistent with adsorption of Np by the solids and provide no evidence of Np incorporation in the bulk solid.

  2. Using Cell Phone Keyboards Is (NP) Hard

    NASA Astrophysics Data System (ADS)

    Boothe, Peter

    Sending text messages on cell phones which only contain the keys 0 through 9 and # and * can be a painful experience. We consider the problem of designing an optimal mapping of numbers to sets of letters to act as an alternative to the standard {2→{abc}, 3→{def}...}. Our overall goal is to minimize the expected number of buttons that must be pressed to enter a message in English. Some variations of the problem are efficiently solvable, either by being small instances or by being in P, but the most realistic version of the problem is NP hard. To prove NP-completeness, we describe a new graph coloring problem UniquePathColoring. We also provide numerical results for the English language on a standard corpus which describe several mappings that improve upon the standard one. With luck, one of these new mappings will achieve success similar to that of the Dvorak layout for computer keyboards.

  3. Gamma beam system at ELI-NP

    SciTech Connect

    Ur, Calin Alexandru

    2015-02-24

    The Gamma Beam System of ELI-NP will produce brilliant, quasi-monochromatic gamma-ray beams via Inverse Compton Scattering of short laser pulses on relativistic electron beam pulses. The scattered radiation is Doppler upshifted by more than 1,000,000 times and is forward focused in a narrow, polarized, tunable, laser-like beam. The gamma-ray beam at ELI-NP will be characterized by large spectral density of about 10{sup 4} photons/s/eV, narrow bandwidth (< 0.5%) and tunable energy from 200 keV up to about 20 MeV. The Gamma Beam System is a state-of-the-art equipment employing techniques and technologies at the limits of the present-day's knowledge.

  4. Electrostatically assisted fabrication of silver-dielectric core/shell nanoparticles thin film capacitor with uniform metal nanoparticle distribution and controlled spacing.

    PubMed

    Li, Xue; Niitsoo, Olivia; Couzis, Alexander

    2016-03-01

    An electrostatically-assisted strategy for fabrication of thin film composite capacitors with controllable dielectric constant (k) has been developed. The capacitor is composed of metal-dielectric core/shell nanoparticle (silver/silica, Ag@SiO2) multilayer films, and a backfilling polymer. Compared with the simple metal particle-polymer mixtures where the metal nanoparticles (NP) are randomly dispersed in the polymer matrix, the metal volume fraction in our capacitor was significantly increased, owing to the densely packed NP multilayers formed by the electrostatically assisted assembly process. Moreover, the insulating layer of silica shell provides a potential barrier that reduces the tunneling current between neighboring Ag cores, endowing the core/shell nanocomposites with a stable and relatively high dielectric constant (k) and low dielectric loss (D). Our work also shows that the thickness of the SiO2 shell plays a dominant role in controlling the dielectric properties of the nanocomposites. Control over metal NP separation distance was realized not only by variation the shell thickness of the core/shell NPs but also by introducing a high k nanoparticle, barium strontium titanate (BST) of relatively smaller size (∼8nm) compared to 80-160nm of the core/shell Ag@SiO2 NPs. The BST assemble between the Ag@SiO2 and fill the void space between the closely packed core/shell NPs leading to significant enhancement of the dielectric constant. This electrostatically assisted assembly method is promising for generating multilayer films of a large variety of NPs over large areas at low cost.

  5. Electrostatically assisted fabrication of silver-dielectric core/shell nanoparticles thin film capacitor with uniform metal nanoparticle distribution and controlled spacing.

    PubMed

    Li, Xue; Niitsoo, Olivia; Couzis, Alexander

    2016-03-01

    An electrostatically-assisted strategy for fabrication of thin film composite capacitors with controllable dielectric constant (k) has been developed. The capacitor is composed of metal-dielectric core/shell nanoparticle (silver/silica, Ag@SiO2) multilayer films, and a backfilling polymer. Compared with the simple metal particle-polymer mixtures where the metal nanoparticles (NP) are randomly dispersed in the polymer matrix, the metal volume fraction in our capacitor was significantly increased, owing to the densely packed NP multilayers formed by the electrostatically assisted assembly process. Moreover, the insulating layer of silica shell provides a potential barrier that reduces the tunneling current between neighboring Ag cores, endowing the core/shell nanocomposites with a stable and relatively high dielectric constant (k) and low dielectric loss (D). Our work also shows that the thickness of the SiO2 shell plays a dominant role in controlling the dielectric properties of the nanocomposites. Control over metal NP separation distance was realized not only by variation the shell thickness of the core/shell NPs but also by introducing a high k nanoparticle, barium strontium titanate (BST) of relatively smaller size (∼8nm) compared to 80-160nm of the core/shell Ag@SiO2 NPs. The BST assemble between the Ag@SiO2 and fill the void space between the closely packed core/shell NPs leading to significant enhancement of the dielectric constant. This electrostatically assisted assembly method is promising for generating multilayer films of a large variety of NPs over large areas at low cost. PMID:26699450

  6. The half-life of 237Np

    NASA Astrophysics Data System (ADS)

    Lowles, I. M.; Mac Mahon, T. D.; Wiltshire, R. A. P.; Crossley, D.; Fudge, A. J.

    1992-02-01

    The only available precise measurement of the half-life of 237Np is that of Brauer et al. (J. Inorg. Nucl. Chem. 12 (1960) 234), which dates from 1960. As a consequence of this radionuclide's importance in fission reactors, the IAEA-CRP requested a confirmatory measurement of the half-life of 237Np. In this present determination the specific activity of 37 sources, prepared from known masses of high purity 237Np solution, have been measured. Accurate concentration analysis of the solution was provided by controlled-potential coulometry. Source activities, in the range 1.0-1.9 kBq. were measured by α-particle counting in two gas flow proportional counters of known geometry. The measured specific activity was 26.03±0.08 Bq μg-1, which corresponds to a half-life of 2.144±0.007 × 106 years, in excellent agreement with the value reported by Brauer et al.

  7. Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se₂/ZnS thin film solar cells.

    PubMed

    Tan, Xiao-Hui; Chen, Yu; Liu, Ye-Xiang

    2014-05-20

    Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se₂ (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased. PMID:24922214

  8. The effect of strain induced by Ag underlayer on saturation magnetization of partially ordered Fe16N2 thin films

    SciTech Connect

    Yang, Meiyin; Allard, Lawrence F.; Ji, Nian; Zhang, Xiaowei; Yu, Guang-Hua; Wang, Jian -Ping

    2013-12-12

    Small angle neutron scattering (SANS) and scanning transmission electron microscopy (STEM) were used to study film formation by magnesium alloys AZ31B (Mg-3Al-1Zn base) and ZE10A (Elektron®717, E717: Mg-1Zn + Nd, Zr) in H2O and D2O with and without 1 or 5 wt.% NaCl. No SANS scattering changes were observed after 24 h D2O or H2O exposures compared with as received (unreacted) alloy, consistent with relatively dense MgO-base film formation. However, exposure to 5 wt.% NaCl resulted in accelerated corrosion, with resultant SANS scattering changes detected. The SANS data indicated both particle and rough surface (internal and external) scattering, but with no preferential size features. The films formed in 5 wt.% NaCl consisted of a thin, inner MgO-base layer, and a nano-porous and filamentous Mg(OH)2 outer region tens of microns thick. Chlorine was detected extending to the inner MgO-base film region, with segregation of select alloying elements also observed in the inner MgO, but not the outer Mg(OH)2. Modeling of the SANS data suggested that the outer Mg(OH)2 films had very high surface areas, consistent with loss of film protectiveness. Here, implications for the NaCl corrosion mechanism, and the potential utility of SANS for Mg corrosion, are discussed.

  9. Enhanced thermal stability of Ag nanorods through capping

    SciTech Connect

    Bachenheimer, Lou; Elliott, Paul; Stagon, Stephen; Huang, Hanchen

    2014-11-24

    Ag nanorods may serve as sensors in the detection of trace amounts of chemical agents, even single molecules, through surface enhanced Raman spectroscopy (SERS). However, thermal coarsening of Ag nanorods near room temperature limits their applications. This letter proposes the use of a thin oxide capping layer to enhance the thermal stability of Ag nanorods beyond 100 °C. Using electron microscopy characterization and SERS tests, the authors show that the proposed method is effective in stabilizing both morphology and sensitivity of Ag nanorods. The results of this work extend the applicability of Ag nanorods as chemical sensors to higher temperatures.

  10. AGS II

    SciTech Connect

    Palmer, R.B.

    1984-01-01

    Interest in rare K decays, neutrino oscillations and other fields have generated an increasing demand for running, and improved intensity and duty cycle, at the AGS. Current projects include acceleration of polarized protons and light ions (up to mass 32). Future plans are for a booster to increase intensity and allow heavy ions (up to mass 200), and a stretcher to give 100% duty cycle. A later upgrade could yield an average current of 32 ..mu.. amps. 6 figures, 2 tables.

  11. Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

    NASA Astrophysics Data System (ADS)

    Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

    2015-09-01

    We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

  12. Theoretical study of the electronic spectra of neutral and cationic NpO and NpO2

    NASA Astrophysics Data System (ADS)

    Kovács, Attila; Infante, Ivan

    2015-08-01

    The electronic spectra of neutral NpO and NpO2 as well as of their mono- (NpO+, NpO2+) and dications (NpO2+, NpO22+) were studied using multiconfigurational relativistic quantum chemical calculations at the complete active space self-consistent field/CASPT2 level of theory taking into account spin-orbit coupling. The active space included 16 orbitals: all the 7s, 6d, and 5f orbitals of neptunium together with selected orbitals of oxygen. The vertical excitation energies on the ground state geometries have been computed up to ca. 35 000 cm-1. The gas-phase electronic spectra were evaluated on the basis of the computed Einstein coefficients at 298 K and 3000 K. The computed vertical transition energies show good agreement with previous condensed-phase results on NpO2+ and NpO22+.

  13. Effect of Front-Side Silver Metallization on Underlying n+-p Junction in Multicrystalline Silicon Solar Cells: Preprint

    SciTech Connect

    Jiang, C. S.; Li, Z. G.; Moutinho, H. R.; Liang, L.; Ionkin, A.; Al-Jassim, M. M.

    2012-06-01

    We report on the effect of front-side Ag metallization on the underlying n+-p junction of multicrystalline Si solar cells. The junction quality beneath the contacts was investigated by characterizing the uniformities of the electrostatic potential and doping concentration across the junction, using scanning Kelvin probe force microscopy and scanning capacitance microscopy. We investigated cells with a commercial Ag paste (DuPont PV159) and fired at furnace setting temperatures of 800 degrees, 840 degrees, and 930 degrees C, which results in actual cell temperatures ~100 degrees C lower than the setting temperature and the three cells being under-, optimal-, and over-fired. We found that the uniformity of the junction beneath the Ag contact was significantly degraded by the over-firing, whereas the junction retained good uniformity with the optimal- and under-fire temperatures. Further, Ag crystallites with widely distributed sizes from <100 nm to several μm were found at the Ag/Si interface of the over-fired cell. Large crystallites were imaged as protrusions into Si deeper than the junction depth. However, the junction was not broken down; instead, it was reformed on the entire front of the crystallite/Si interface. We propose a mechanism of the junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent recrystallization with incorporation of impurities in the Ag paste and with formation of crystallographic defects during quenching.

  14. Toxicological Effects of Caco-2 Cells Following Short-Term and Long-Term Exposure to Ag Nanoparticles

    PubMed Central

    Chen, Ni; Song, Zheng-Mei; Tang, Huan; Xi, Wen-Song; Cao, Aoneng; Liu, Yuanfang; Wang, Haifang

    2016-01-01

    Extensive utilization increases the exposure of humans to Ag nanoparticles (NPs) via the oral pathway. To comprehensively address the action of Ag NPs to the gastrointestinal systems in real situations, i.e., the long-term low-dose exposure, we evaluated and compared the toxicity of three Ag NPs (20–30 nm with different surface coatings) to the human intestine cell Caco-2 after 1-day and 21-day exposures, using various biological assays. In both the short- and long-term exposures, the variety of surface coating predominated the toxicity of Ag NPs in a descending order of citrate-coated Ag NP (Ag-CIT), bare Ag NP (Ag-B), and poly (N-vinyl-2-pyrrolidone)-coated Ag NP (Ag-PVP). The short-term exposure induced cell growth inhibition and death. The cell viability loss appeared after cells were exposed to 0.7 μg/mL Ag-CIT, 0.9 μg/mL Ag-B or >1.0 μg/mL Ag-PVP for 24 h. The short-term and higher-dose exposure also induced reactive oxygen species (ROS) generation, mitochondrial damage, cell membrane leakage, apoptosis, and inflammation (IL-8 level). The long-term exposure only inhibited the cell proliferation. After 21-day exposure to 0.4 μg/mL Ag-CIT, the cell viability dropped to less than 50%, while cells exposed to 0.5 μg/mL Ag-PVP remained normal as the control. Generally, 0.3 μg/mL is the non-toxic dose for the long-term exposure of Caco-2 cells to Ag NPs in this study. However, cells presented inflammation after exposure to Ag NPs with the non-toxic dose in the long-term exposure. PMID:27338357

  15. The investigation of a series of n-hydroxybenzoic acids (n=p, m, o) on a new surface enhanced Raman scattering active substrate.

    PubMed

    Wang, Li-Ran; Fang, Yan

    2005-12-01

    Ag nanoparticles, organized on indium tin oxide (ITO) surface, can act as a new surface enhanced Raman scattering (SERS) active substrate as well as a dry electrode. Compared with the traditional SERS-active substrate, its notable advantage is that the microcosmic changes of the film can be reflected by the SERS spectrum during the investigation of the film's electrical and other macroscopic characteristics. To illuminate the above-mentioned property of this new substrate, a series of n-hydroxybenzoic acids (n-HBA; n=p, m and o) was tested as probe molecules by SERS technique. These SERS spectra indicate that the significant changes of frequencies as well as intensities, respectively, arise from the changes of the adsorption behavior along with the proportional variation of molecules and silver nanoparticles. Excellent SERS signals prove that the silver nanoparticles-coated ITO is a highly SERS-active substrate and can efficiently reflect the microcosmic property of the film, which suggest it has promising potential of being a new technique for further application in the field of thin-film research.

  16. np -> d gamma for big bang nucleosynthesis

    SciTech Connect

    Jiunn-Wei Chen; Martin J. Savage

    1999-12-01

    The cross section from np -> dy is calculated at energies relevant to big-bang nucleosynthesis using the recently developed effective field theory that describes the two nucleon sector. The E1 amplitude is computed up to N{sup 3}LO and depends only upon nucleon-nucleon phase shift data. In contrast, the M1 contribution is determined by the cross section for cold neutron capture. The uncertainty in the calculation for nucleon energies up to E{approx}1 MeV is estimated to be <= 4%.

  17. Impact of the formation of NpO{sub 2} and Np{sub 2}O{sub 5} on the Np solubility in YM waters

    SciTech Connect

    Runde, W.; Janecky, D.; Kaszuba, J.; Tait, C.D.

    1998-01-01

    The objective of this activity is to evaluate the impact of different Np solids on the solubility of neptunium in YM waters. Special interest is on the impact of Np{sub 2}O{sub 5} found in solubility experiments as the Np solid phase. The formation and stability of Np{sub 2}O{sub 5} is discussed and its stability calculated in J-13 based upon new solubility data. Clearly, the results show that Np{sub 2}O{sub 5} is the most stable Np(V) solid phase that determined the solubility of neptunium under aerobic conditions. Both solubility experiments and geochemical modeling show a decrease of the neptunium solubility in J-13 of about two orders of magnitude (compared to previously reported results) based on the new solubility data. Under anaerobic conditions NpO{sub 2} is the most stable Np bearing solid phase. Its formation would decrease the Np solubility by several orders of magnitude.

  18. In situ assembly of well-dispersed Ag nanoparticles (AgNPs) on electrospun carbon nanofibers (CNFs) for catalytic reduction of 4-nitrophenol.

    PubMed

    Zhang, Peng; Shao, Changlu; Zhang, Zhenyi; Zhang, Mingyi; Mu, Jingbo; Guo, Zengcai; Liu, Yichun

    2011-08-01

    Carbon nanofibers/silver nanoparticles (CNFs/AgNPs) composite nanofibers were fabricated by two steps consisting of the preparation of the CNFs by electrospinning and the hydrothermal growth of the AgNPs on the CNFs. The as-prepared nanofibers were characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, resonant Raman spectra, thermal gravimetric and differential thermal analysis, and X-ray photoelectron spectroscopy, respectively. The results indicated that not only were AgNPs (25-50 nm) successfully grown on the CNFs but also the AgNPs were distributed without aggregation on the CNFs. Further more, by adjusting the parameters in hydrothermal processing, the content of silver supported on the CNFs could be easily controlled. The catalytic activities of the CNFs/AgNPs composite nanofibers to the reduction of 4-nitrophenol (4-NP) with NaBH(4) were tracked by UV-visible spectroscopy. It was suggested that the CNFs/AgNPs composite nanofibers exhibited high catalytic activity in the reduction of 4-NP, which might be attributed to the high surface areas of AgNPs and synergistic effect on delivery of electrons between CNFs and AgNPs. And, the catalytic efficiency was enhanced with the increasing of the content of silver on the CNFs/AgNPs composite nanofibers. Notably, the CNFs/AgNPs composite nanofibers could be easily recycled due to their one-dimensional nanostructural property.

  19. Oxygen Reduction at Very Low Overpotential on Nanoporous Ag Catalysts

    DOE PAGES

    Zhou, Yang; Lu, Qi; Zhuang, Zhongbin; Hutchings, Gregory S.; Kattel, Shyam; Yan, Yushan; Chen, Jingguang G.; Xiao, John Q.; Jiao, Feng

    2015-05-07

    Here we report a monolithic nanoporous Ag (np-Ag) material, synthesized using the dealloying method, as high-performance catalysts for ORR in alkaline media. As shown in Scheme 1, when there is insufficient potential input, the O2 molecules are more likely to rebound off from a planar electrode surface (i.e. bulk polycrystalline metal, films made from nanoparticles or nanowires) before they could be reduced. In contrast, they are more likely to be trapped inside the monolithic nanoporous structure, contacting with catalytic surface for multiple time, which greatly enhances the chance for them to be fully reduced. As a result, the np-Ag catalystmore » is able to achieve an equivalent or better ORR performance than the state-of the-art Pt/C catalyst at low overpotentials, which is most desired in electrochemical energy applications for maximizing efficiency.« less

  20. Oxygen Reduction at Very Low Overpotential on Nanoporous Ag Catalysts

    SciTech Connect

    Zhou, Yang; Lu, Qi; Zhuang, Zhongbin; Hutchings, Gregory S.; Kattel, Shyam; Yan, Yushan; Chen, Jingguang G.; Xiao, John Q.; Jiao, Feng

    2015-05-07

    Here we report a monolithic nanoporous Ag (np-Ag) material, synthesized using the dealloying method, as high-performance catalysts for ORR in alkaline media. As shown in Scheme 1, when there is insufficient potential input, the O2 molecules are more likely to rebound off from a planar electrode surface (i.e. bulk polycrystalline metal, films made from nanoparticles or nanowires) before they could be reduced. In contrast, they are more likely to be trapped inside the monolithic nanoporous structure, contacting with catalytic surface for multiple time, which greatly enhances the chance for them to be fully reduced. As a result, the np-Ag catalyst is able to achieve an equivalent or better ORR performance than the state-of the-art Pt/C catalyst at low overpotentials, which is most desired in electrochemical energy applications for maximizing efficiency.

  1. Antiferromagnetic ground state in NpCoGe

    NASA Astrophysics Data System (ADS)

    Colineau, E.; Griveau, J.-C.; Eloirdi, R.; Gaczyński, P.; Khmelevskyi, S.; Shick, A. B.; Caciuffo, R.

    2014-03-01

    NpCoGe, the neptunium analog of the ferromagnetic superconductor UCoGe, has been investigated by dc magnetization, ac susceptibility, specific heat, electrical resistivity, Hall effect, 237Np Mössbauer spectroscopy, and local spin-density approximation (LSDA) calculations. NpCoGe exhibits an antiferromagnetic ground state with a Néel temperature TN≈13 K and an average ordered magnetic moment <μNp>=0.80μB. The magnetic phase diagram has been determined and shows that the antiferromagnetic structure is destroyed by the application of a magnetic field (≈3 T). The value of the isomer shift suggests a Np3+ charge state (configuration 5f4). A high Sommerfeld coefficient value for NpCoGe (170 mJ mol-1 K-2) is inferred from specific heat. LSDA calculations indicate strong magnetic anisotropy and easy magnetization along the c axis. Mössbauer data and calculated exchange interactions support the possible occurrence of an elliptical spin-spiral structure in NpCoGe. The comparison with NpRhGe and uranium analogs suggests the leading role of 5f-d hybridization, the rather delocalized character of 5f electrons in NpCoGe, and the possible proximity of NpRuGe or NpFeGe to a magnetic quantum critical point.

  2. Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells

    PubMed Central

    Katsumiti, Alberto; Gilliland, Douglas; Arostegui, Inmaculada; Cajaraville, Miren P.

    2015-01-01

    Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag. PMID:26061169

  3. A stretchable strain sensor based on a metal nanoparticle thin film for human motion detection.

    PubMed

    Lee, Jaehwan; Kim, Sanghyeok; Lee, Jinjae; Yang, Daejong; Park, Byong Chon; Ryu, Seunghwa; Park, Inkyu

    2014-10-21

    Wearable strain sensors for human motion detection are being highlighted in various fields such as medical, entertainment and sports industry. In this paper, we propose a new type of stretchable strain sensor that can detect both tensile and compressive strains and can be fabricated by a very simple process. A silver nanoparticle (Ag NP) thin film patterned on the polydimethylsiloxane (PDMS) stamp by a single-step direct transfer process is used as the strain sensing material. The working principle is the change in the electrical resistance caused by the opening/closure of micro-cracks under mechanical deformation. The fabricated stretchable strain sensor shows highly sensitive and durable sensing performances in various tensile/compressive strains, long-term cyclic loading and relaxation tests. We demonstrate the applications of our stretchable strain sensors such as flexible pressure sensors and wearable human motion detection devices with high sensitivity, response speed and mechanical robustness. PMID:25175360

  4. The role of exopolymeric substances in the bioaccumulation and toxicity of Ag nanoparticles to algae.

    PubMed

    Zhou, Kaijun; Hu, Yi; Zhang, Luqing; Yang, Kun; Lin, Daohui

    2016-01-01

    Exopolymeric substances (EPS) have an important role in bioaccumulation and toxicity of nanoparticles (NPs) to algae, which warrants specific studies. The interaction of EPS with citrate and polyvinyl pyrrolidone (PVP) coated AgNPs (C-AgNPs and P-AgNPs, respectively) and its roles in bioaccumulation and toxicity of the AgNPs to Chlorella pyrenoidosa were investigated. The amino and aromatic carboxylic groups in the EPS were involved in the EPS-AgNP interactions. Compared with Ag(+), C-AgNPs had comparable total bioaccumulation but greater absorption by intact algae with EPS; P-AgNPs had the smallest total bioaccumulation and were mainly adsorbed on algal surfaces. With EPS removed, the total bioaccumulations and surface adsorptions for the three Ag species decreased but the cell internalizations increased; the 96 h half growth inhibition concentrations decreased, indicating EPS alleviated the algal toxicity of Ag. The cell-internalized but not the adsorbed AgNPs could contribute to the nanotoxicity. The EPS could bind both AgNPs and Ag(+), and thus inhibited the cell internalization and the nanotoxicity. However, the EPS-bound Ag on the cell surfaces would migrate along with the algae and be biologically amplified in the aquatic food chains, presenting ecological risks. These results are helpful for understanding the fate and ecological effects of NPs. PMID:27615743

  5. The role of exopolymeric substances in the bioaccumulation and toxicity of Ag nanoparticles to algae

    PubMed Central

    Zhou, Kaijun; Hu, Yi; Zhang, Luqing; Yang, Kun; Lin, Daohui

    2016-01-01

    Exopolymeric substances (EPS) have an important role in bioaccumulation and toxicity of nanoparticles (NPs) to algae, which warrants specific studies. The interaction of EPS with citrate and polyvinyl pyrrolidone (PVP) coated AgNPs (C-AgNPs and P-AgNPs, respectively) and its roles in bioaccumulation and toxicity of the AgNPs to Chlorella pyrenoidosa were investigated. The amino and aromatic carboxylic groups in the EPS were involved in the EPS-AgNP interactions. Compared with Ag+, C-AgNPs had comparable total bioaccumulation but greater absorption by intact algae with EPS; P-AgNPs had the smallest total bioaccumulation and were mainly adsorbed on algal surfaces. With EPS removed, the total bioaccumulations and surface adsorptions for the three Ag species decreased but the cell internalizations increased; the 96 h half growth inhibition concentrations decreased, indicating EPS alleviated the algal toxicity of Ag. The cell-internalized but not the adsorbed AgNPs could contribute to the nanotoxicity. The EPS could bind both AgNPs and Ag+, and thus inhibited the cell internalization and the nanotoxicity. However, the EPS-bound Ag on the cell surfaces would migrate along with the algae and be biologically amplified in the aquatic food chains, presenting ecological risks. These results are helpful for understanding the fate and ecological effects of NPs. PMID:27615743

  6. The role of exopolymeric substances in the bioaccumulation and toxicity of Ag nanoparticles to algae

    NASA Astrophysics Data System (ADS)

    Zhou, Kaijun; Hu, Yi; Zhang, Luqing; Yang, Kun; Lin, Daohui

    2016-09-01

    Exopolymeric substances (EPS) have an important role in bioaccumulation and toxicity of nanoparticles (NPs) to algae, which warrants specific studies. The interaction of EPS with citrate and polyvinyl pyrrolidone (PVP) coated AgNPs (C-AgNPs and P-AgNPs, respectively) and its roles in bioaccumulation and toxicity of the AgNPs to Chlorella pyrenoidosa were investigated. The amino and aromatic carboxylic groups in the EPS were involved in the EPS-AgNP interactions. Compared with Ag+, C-AgNPs had comparable total bioaccumulation but greater absorption by intact algae with EPS; P-AgNPs had the smallest total bioaccumulation and were mainly adsorbed on algal surfaces. With EPS removed, the total bioaccumulations and surface adsorptions for the three Ag species decreased but the cell internalizations increased; the 96 h half growth inhibition concentrations decreased, indicating EPS alleviated the algal toxicity of Ag. The cell-internalized but not the adsorbed AgNPs could contribute to the nanotoxicity. The EPS could bind both AgNPs and Ag+, and thus inhibited the cell internalization and the nanotoxicity. However, the EPS-bound Ag on the cell surfaces would migrate along with the algae and be biologically amplified in the aquatic food chains, presenting ecological risks. These results are helpful for understanding the fate and ecological effects of NPs.

  7. Product evolution in the Np(IV) fluorophosphate system

    SciTech Connect

    Bray, Travis H.; Sullens, Tyler A.; Shvareva, Tatiana Y.; Sykora, Richard E.; Haire, Richard G.; Albrecht-Schmitt, Thomas E.

    2007-01-15

    The reaction of {sup 237}NpO{sub 2} with Cs{sub 2}CO{sub 3}, Ga{sub 2}O{sub 3}, H{sub 3}PO{sub 4}, and HF under mild hydrothermal conditions leads to the formation of NpFPO{sub 4} after 4 days at 180 deg. C. Heating at 180 deg. C for an additional 6 days leads to the crystallization of Cs{sub 2}Np{sub 2}F{sub 7}PO{sub 4} and NpF{sub 4}. The Ga{sub 2}O{sub 3} forms a GaPO{sub 4} matrix in which crystals of NpFPO{sub 4}, Cs{sub 2}Np{sub 2}F{sub 7}PO{sub 4}, and NpF{sub 4} grow. Single crystal X-ray data reveal that the structure of NpFPO{sub 4} consists of Np(IV) centers bound by both fluoride and phosphate to yield [NpF{sub 2}O{sub 6}] distorted dodecahedra. These are linked by corner-sharing with fluoride and both corner- and edge-sharing with phosphate to yield a dense, three-dimensional network. The structure of Cs{sub 2}Np{sub 2}F{sub 7}PO{sub 4} is complex and contains both distorted dodecahedral [NpO{sub 2}F{sub 6}] and tricapped trigonal prismatic [NpO{sub 2}F{sub 7}] environments around Np(IV) that are linked with each other through corner- and edge-sharing, and with the phosphate groups to create a three-dimensional structure. There are small channels extending down the a-axis in Cs{sub 2}Np{sub 2}F{sub 7}PO{sub 4}. Crystallographic data: NpFPO{sub 4}, orthorhombic, space group Pnma, a=8.598(2), b=6.964(1), c=6.337(1) A, Z=4, V=379.44(13) A{sup 3}, R(F)=3.53% for 40 parameters and 465 reflections with I>2{sigma}(I) (T=193 K); Cs{sub 2}Np{sub 2}F{sub 7}PO{sub 4}, monoclinic, space group P2{sub 1}/c, a=8.8727(4), b=16.2778(7), c=7.8009(4) A, {beta}=112.656(1), Z=4, V=1039.73(8) A{sup 3}, R(F)=2.27% for 146 parameters and 2465 reflections with I>2{sigma}(I) (T=193 K). - Graphical abstract: Two Np(IV) fluorophosphates, NpFPO{sub 4} and Cs{sub 2}Np{sub 2}F{sub 7}PO{sub 4}, have been prepared as single crystals under hydrothermal conditions. NpFPO{sub 4} crystallizes first, then reacts to yield Cs{sub 2}Np{sub 2}F{sub 7}PO{sub 4} and finally yields NpF{sub 4

  8. Hydrothermal synthesis, structure, and magnetic properties of the mixed-valent Np(IV)/Np(V) selenite, Np(NpO{sub 2}){sub 2}(SeO{sub 3}){sub 3}.

    SciTech Connect

    Almond, P. M.; Sykora, R. E.; Skanthakumar, S.; Soderholm, L.; Albrecht-Schmitt, T. E.; Chemistry; Auburn Univ.

    2004-02-09

    The reaction of NpO{sub 2} with SeO{sub 2} in the presence of CsCl at 180 {sup o}C results in the formation of Np(NpO{sub 2}){sub 2}(SeO{sub 3}){sub 3} (1). The structure of 1 consists of three crystallographically unique Np centers with three different coordination environments in two different oxidation states. Np(1) is found in a neptunyl(V), ONpO{sup +}, unit that is further ligated in the equatorial plane by three chelating SeO{sub 3}{sup 2-} anions to create a hexagonal bipyramidal NpO{sub 8} unit. A second neptunyl(V) cation also occurs for Np(2); it is bound by four bridging selenite anions and by the oxo atom from the Np(1) neptunyl cation to form a pentagonal bipyramidal, NpO{sub 7}, unit. The third neptunium center, Np(3), which contains Np(IV), is found in a distorted NpO{sub 8} dodecahedron. Np(3) is bound by five bridging selenite anions and by three neptunyl units via cation-cation interactions. The NpO{sub 7} pentagonal bipyramids and NpO{sub 8} hexagonal bipyramids share both corners and edges. Both of these polyhedra share corners via cation-cation interactions with the NpO{sub 8} dodecahedra creating a three-dimensional structure with small channels that house the stereochemically active lone pair of electrons on the selenite anions. Magnetic susceptibility data follow Curie-Weiss behavior over the entire temperature range measured (5 {<=} T {<=} 320 K). The effective moment, {mu}{sub eff} = 2.28 {mu}{sub B}, which represents an average over the three crystallographically inequivalent Np atoms, is within the expected range of values. There is no evidence of long-range ordering of the Np moments at temperatures down to 5 K, consistent with the negligible Weiss constant determined from fitting the susceptibility data. Crystallographic data: 1, orthorhombic, space group Pbca, a = 10.6216(5), b = 11.9695(6), and c = 17.8084(8) {angstrom} and Z = 8 (T = 193 K).

  9. Contextual reasoning is NP-complete

    SciTech Connect

    Massacci, F.

    1996-12-31

    The logic of context with the ist (c, p) modality has been proposed by McCarthy as a foundation for contextual reasoning. This paper shows that propositional logic of context is NP-complete and therefore more tractable than multimodal logics or Multi Language hierarchical logics which are PSPACE-complete. This result is given in a proof-theoretical way by providing a tableau calculus, which can be used as a decision procedure for automated reasoning. The computational gap between logic of context and modal logics is analyzed and some indications for the use of either formalisms are drawn on the basis of the tradeoff between compactness of representation and tractability of reasoning.

  10. A stretchable strain sensor based on a metal nanoparticle thin film for human motion detection

    NASA Astrophysics Data System (ADS)

    Lee, Jaehwan; Kim, Sanghyeok; Lee, Jinjae; Yang, Daejong; Park, Byong Chon; Ryu, Seunghwa; Park, Inkyu

    2014-09-01

    Wearable strain sensors for human motion detection are being highlighted in various fields such as medical, entertainment and sports industry. In this paper, we propose a new type of stretchable strain sensor that can detect both tensile and compressive strains and can be fabricated by a very simple process. A silver nanoparticle (Ag NP) thin film patterned on the polydimethylsiloxane (PDMS) stamp by a single-step direct transfer process is used as the strain sensing material. The working principle is the change in the electrical resistance caused by the opening/closure of micro-cracks under mechanical deformation. The fabricated stretchable strain sensor shows highly sensitive and durable sensing performances in various tensile/compressive strains, long-term cyclic loading and relaxation tests. We demonstrate the applications of our stretchable strain sensors such as flexible pressure sensors and wearable human motion detection devices with high sensitivity, response speed and mechanical robustness.Wearable strain sensors for human motion detection are being highlighted in various fields such as medical, entertainment and sports industry. In this paper, we propose a new type of stretchable strain sensor that can detect both tensile and compressive strains and can be fabricated by a very simple process. A silver nanoparticle (Ag NP) thin film patterned on the polydimethylsiloxane (PDMS) stamp by a single-step direct transfer process is used as the strain sensing material. The working principle is the change in the electrical resistance caused by the opening/closure of micro-cracks under mechanical deformation. The fabricated stretchable strain sensor shows highly sensitive and durable sensing performances in various tensile/compressive strains, long-term cyclic loading and relaxation tests. We demonstrate the applications of our stretchable strain sensors such as flexible pressure sensors and wearable human motion detection devices with high sensitivity, response

  11. Dual regulation of the {delta}Np63 transcriptional activity by {delta}Np63 in human nasopharyngeal carcinoma cell

    SciTech Connect

    Chu, W.-K.; Lee, K.-C.; Chow, S.-E.; Chen, J.-K. . E-mail: jkc508@mail.cgu.edu.tw

    2006-04-21

    p63 splicing variants lacking NH{sub 2}-terminal transactivating domain, known as {delta}Np63, are thought to antagonize p53 and p63 functions and are suggested to play roles in keratinocyte differentiation. Here, we show that {delta}Np63 has a dual-regulatory effect on the activity of its own promoter in NPC-076 cell. Down-regulation of the transcriptional activity is observed when {delta}Np63 is present in low levels. In contrast, up-regulation of {delta}Np63 transcriptional activity is observed when {delta}Np63 is expressed at higher levels. The down-regulation effect is abolished when the p53-binding site of the {delta}Np63 promoter is mutated. In sharp contrast, similar mutation does not affect the up-regulation of the {delta}Np63 transcriptional activity under the same experimental conditions. Further study shows that the up-regulation is correlated with the activation of the STAT3, as the blockade of STAT3 nuclear translocation abolishes the up-regulation by {delta}Np63. Thus, {delta}Np63 exerts a bidirectional regulation of the {delta}Np63 transcriptional activity in NPC-076 cell.

  12. Neptunyl (Np) interaction with green rust, GRNa,SO4

    NASA Astrophysics Data System (ADS)

    Christiansen, B. C.; Geckeis, H.; Marquardt, C. M.; Bauer, A.; Römer, J.; Wiss, T.; Schild, D.; Stipp, S. L. S.

    2011-03-01

    Green rust (GR), a member of the Fe(II),Fe(III) layered double hydroxide mineral family, forms in groundwater and during steel corrosion. It has high surface area and is very reactive, especially for redox-sensitive elements such as some actinides. During neutron irradiation of nuclear fuel in a reactor, 237Np develops. Although the abundance of Np in spent nuclear fuel is only about 0.05% by mass, it has a very long half life, 2.14 × 10 6 years, so there is concern about its mobility in the distant future, when radioactive storage sites might be expected to degrade. Under oxidizing conditions, as are expected from radiolysis in a repository, the very mobile neptunyl-ion, Np O2+, would be the dominant aqueous neptunium species. In this work, we investigated the interaction of Np O2+ with green rust sodium sulphate ( GR). The aim of the study was to define the processes involved, to determine the final redox speciation of Np, hence its potential mobility, and to characterise changes in the green rust. The GR sorbed and reduced Np O2+ within minutes. Reduced Np(IV) was primarily found as precipitated nanoparticles at the edges of the GR crystal platelets. The position of the particles at the crystal edges suggests initial sorption of Np(V) and subsequent reduction at GR edge sites. In further experiments, Np-containing GR was allowed to oxidise completely in aqueous suspension. Surprisingly, about 50% of the Np remained associated with the oxidised product and about 75% of the associated Np was still present as Np(IV).

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

    SciTech Connect

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

    1990-12-01

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

  14. Ferro- and antiferro-magnetism in (Np, Pu)BC

    NASA Astrophysics Data System (ADS)

    Klimczuk, T.; Shick, A. B.; Kozub, A. L.; Griveau, J.-C.; Colineau, E.; Falmbigl, M.; Wastin, F.; Rogl, P.

    2015-04-01

    Two new transuranium metal boron carbides, NpBC and PuBC, have been synthesized. Rietveld refinements of powder XRD patterns of {Np,Pu}BC confirmed in both cases isotypism with the structure type of UBC. Temperature dependent magnetic susceptibility data reveal antiferromagnetic ordering for PuBC below TN = 44 K, whereas ferromagnetic ordering was found for NpBC below TC = 61 K. Heat capacity measurements prove the bulk character of the observed magnetic transition for both compounds. The total energy electronic band structure calculations support formation of the ferromagnetic ground state for NpBC and the antiferromagnetic ground state for PuBC.

  15. Raman scattering of linear chains of strongly coupled Ag nanoparticles on SWCNTs

    PubMed Central

    Valmalette, Jean-Christophe; Tan, Zhenquan; Abe, Hiroya; Ohara, Satoshi

    2014-01-01

    We compare the Raman scattering properties of hybrid nanostructures consisting of Ag nanoparticles (NPs) in disordered and aligned arrangements on single-walled carbon nanotubes (SWCNTs) as a result of chemical and photoreduction methods. In the latter case, the unique structure of the very small Ag NP (from 4 to 7 nm) chains generated an extremely large mode at 969 cm−1 that was assigned to the sulphate-silver interaction at the NP surface. Another strong mode was present at 1201 cm−1 and was assigned to an IR-active mode of sodium dodecyl sulphate (SDS); this mode was observed because the symmetry changes altered the selection rules. We demonstrate that both the UV photoreduction of silver and the presence of SWCNTs are necessary to produce this very strong Raman scattering. The Raman modes of the SWCNTs are also significantly modified by the presence of Ag NP chains along the nanotubes. PMID:24912409

  16. Preparation, characterization, and photocatalytic activity of porous AgBr@Ag and AgBrI@Ag plasmonic photocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Tian, Baozhu; Zhang, Jinlong; Xiong, Tianqing; Wang, Tingting

    2014-02-01

    Porous AgBr@Ag and AgBrI@Ag plasmonic photocatalysts were synthesized by a multistep route, including a dealloying method to prepare porous Ag, a transformation from Ag to AgBr and AgBrI, and a photo-reduction process to form Ag nanoparticles on the surface of AgBr and AgBrI. It was found that the porous structure kept unchanged during Ag was transferred into AgBr, AgBrI, AgBr@Ag, and AgBrI@Ag. Both porous AgBr@Ag and porous AgBrI@Ag showed much higher visible-light photocatalytic activity than cubic AgBr@Ag for the degradation of methyl orange, which is because the interconnected pore channels not only provide more reactive sites but also favor the transportation of photo-generated electrons and holes. For AgBrI@Ag, AgBrI solid solution formed at the interface of AgBr and AgI, and the phase junction can effectively separate the photo-generated electrons and holes, favorable to the improvement of photocatalytic activity. The optimal I content for obtaining the highest activity is ∼10 at.%.

  17. Improvement of critical current density and thermally assisted individual vortex depinning in pulsed-laser-deposited YBa2Cu3O7-δ thin films on SrTiO3 (100) substrate with surface modification by Ag nanodots

    NASA Astrophysics Data System (ADS)

    Li, A. H.; Liu, H. K.; Ionescu, M.; Wang, X. L.; Dou, S. X.; Collings, E. W.; Sumption, M. D.; Bhatia, M.; Lin, Z. W.; Zhu, J. G.

    2005-05-01

    YBa2Cu3O7 films were fabricated by pulsed laser deposition on SrTiO3 (100) single-crystal substrates whose surfaces were modified by the introduction of Ag nanodots. The critical current density (Jc) was found to increase with the number of Ag shots. Zero-field magnetic Jc0 at 77K increased from 8×105 up to 3.5×106A /cm2 as the number of Ag shots increased from 0 to over 150 times. Microstructure investigations indicated that the crystallinity and the ab alignment gradually improved as the number of Ag nanodots increased. Thermally activated depinning of individual vortices is suggested responsible for a field-independent Jc plateau.

  18. Unaffected features of BSA stabilized Ag nanoparticles after storage and reconstitution in biological relevant media.

    PubMed

    Valenti, Laura E; Giacomelli, Carla E

    2015-08-01

    Silver-coated orthopedic implants and silver composite materials have been proposed to produce local biocidal activity at low dose to reduce post-surgery infection that remains one of the major contributions to the patient morbidity. This work presents the synthesis combined with the characterization, colloidal stability in biological relevant media, antimicrobial activity and handling properties of silver nanoparticles (Ag-NP) before and after freeze dry and storage. The nanomaterial was synthesized in aqueous solution with simple, reproducible and low-cost strategies using bovine serum albumin (BSA) as the stabilizing agent. Ag-NP were characterized by means of the size distribution and morphology (UV-vis spectra, dynamic light scattering measurements and TEM images), charge as a function of the pH (zeta potential measurements) and colloidal stability in biological relevant media (UV-vis spectra and dynamic light scattering measurements). Further, the interactions between the protein and Ag-NP were evaluated by surface enhanced Raman spectroscopy (SERS) and the antimicrobial activity was tested with two bacteria strains (namely Staphylococcus aureus and Staphylococcus epidermidis) mainly present in the infections caused by implants and prosthesis in orthopedic surgery. Finally, the Ag-NP dispersed in aqueous solution were dried and stored as long-lasting powders that were easily reconstituted without losing their stability and antimicrobial properties. The proposed methods to stabilize Ag-NP not only produce stable dispersions in media of biological relevance but also long-lasting powders with optimal antimicrobial activity in the nanomolar range. This level is much lower than the cytotoxicity determined in vitro on osteoblasts, osteoclasts and osteoarthritic chondrocytes. The synthesized Ag-NP can be incorporated as additive of biomaterials or pharmaceutical products to confer antimicrobial activity in a powdered form in different formulations, dispersed in

  19. Enhancing photocatalysis in SrTiO3 by using Ag nanoparticles: A two-step excitation model for surface plasmon-enhanced photocatalysis.

    PubMed

    Ma, Lei; Sun, Tao; Cai, Hua; Zhou, Zhi-Quan; Sun, Jian; Lu, Ming

    2015-08-28

    Surface plasmon (SP)-enhanced ultraviolet and visible photocatalytic activities of SrTiO3 (STO) are observed after incorporating Ag nanoparticles (Ag-NPs) on STO surfaces. A two-step excitation model is proposed to explain the SP-enhanced photocatalysis. The point of the model is that an electron at the valence band of STO is first excited onto the Fermi level of Ag-NP by the SP field generated on the Ag-NP, and then injected into the conduction band of STO from the SP band, leaving a hole at the valence band of STO. A full redox catalytic reaction at the surface of STO is then available. For Ag-NP incorporated STO, up-converted and inter-band photoluminescence emissions of STO are observed, and nonlinear evolutions of photocatalytic activity with illumination light powers are found. Furthermore, near infrared photocatalysis is detected. These results support the proposed model.

  20. Enhancing photocatalysis in SrTiO{sub 3} by using Ag nanoparticles: A two-step excitation model for surface plasmon-enhanced photocatalysis

    SciTech Connect

    Ma, Lei; Sun, Tao; Cai, Hua; Zhou, Zhi-Quan; Sun, Jian E-mail: minglu55@fudan.edu.cn; Lu, Ming E-mail: minglu55@fudan.edu.cn

    2015-08-28

    Surface plasmon (SP)-enhanced ultraviolet and visible photocatalytic activities of SrTiO{sub 3} (STO) are observed after incorporating Ag nanoparticles (Ag-NPs) on STO surfaces. A two-step excitation model is proposed to explain the SP-enhanced photocatalysis. The point of the model is that an electron at the valence band of STO is first excited onto the Fermi level of Ag-NP by the SP field generated on the Ag-NP, and then injected into the conduction band of STO from the SP band, leaving a hole at the valence band of STO. A full redox catalytic reaction at the surface of STO is then available. For Ag-NP incorporated STO, up-converted and inter-band photoluminescence emissions of STO are observed, and nonlinear evolutions of photocatalytic activity with illumination light powers are found. Furthermore, near infrared photocatalysis is detected. These results support the proposed model.

  1. Nanoalloy composition-temperature phase diagram for catalyst design: Case study of Ag-Au

    SciTech Connect

    Wang, Lin-Lin; Tan, Teck L.; Johnson, Duane D.

    2012-07-23

    By coupling a cluster expansion with density functional theory (DFT) calculations, we determine the configurational thermodynamics (site preferences and occupations) for alloyed nanoparticles (NPs) as functions of composition (c) and temperature (T), exemplified using a 55-atom Ag-Au truncated cuboctahedron NP. The c-T phase diagram for site occupations gives detailed design information for alloyed NP, especially the thermodynamically stable active sites for catalysis and how they change with stoichiometry and processing temperature. Generally, Ag prefers core and Au prefers shell, agreeing with our universal core-shell preference assessed from DFT impurity segregation energies but with interesting multishell configurations having specific active sites.

  2. Stability of Ag nanoparticles dispersed in amphiphilic organic matrix

    NASA Astrophysics Data System (ADS)

    Suvorova, Elena I.; Klechkovskaya, Vera V.; Kopeikin, Victor V.; Buffat, Philippe A.

    2005-02-01

    Nano- and thin-film technologies based on novel systems associating metals particles to polymer matrix open a broad range of different applications. Such composites were found to be more efficient and safe, for instance, in biomedical needs. The Ag/poly(N-vinyl-2-pyrrolidone) (Ag/PVP) composite investigated in the present work is a new bactericide mean applied in complicated cases of infected burns and purulent wounds. High-resolution transmission electron microscopy (HRTEM) and X-ray energy-dispersive (EDS) microanalysis were used to bring chemical and structural information in a study of the properties and stability of thin-film nanocomposite whih consisted of Ag nanoparticles dispersed in water-soluble organic matrix poly(N-vinyl-2-pyrrolidone). The nanostructural investigation of Ag/PVP composite by HRTEM and EDS exposed to SO 2 and H 2S from the atmosphere and some traces of S-containing substances explains the limited stability of this system by a structural modification associated with a phase change and formation of Ag 2S and Ag 2SO 3. However, formation of the hardly water-soluble Ag 2S and Ag 2SO 3 salts may play an important role in the suppression of bacterial growth. On the one hand, silver could block S-H groups in vital proteins and conduced to their destruction, in that way revealing the antibacterial power. On the other hand, antiseptic properties of Ag consist in binding the products of the protein decay.

  3. Fabrication of Sn-3.5Ag Eutectic Alloy Powder by Annealing Sub-Micrometer Sn@Ag Powder Prepared by Citric Acid-Assisted Ag Immersion Plating.

    PubMed

    Chee, Sang-Soo; Choi, Eun Byeol; Lee, Jong-Hyun

    2015-11-01

    A Sn-3.5Ag eutectic alloy powder has been developed by chemically synthesizing sub-micrometer Sn@Ag powder at room temperature. This synthesis was achieved by first obtaining a sub-micrometer Sn powder for the core using a modified variant of the polyol method, and then coating this with a uniformly thin and continuous Ag layer through immersion plating in 5.20 mM citric acid. The citric acid was found to play multiple roles in the Ag coating process, acting as a chelating agent, a reducing agent and a stabilizer to ensure coating uniformity; and as such, the amount used has an immense influence on the coating quality of the Ag shells. It was later verified by transmission electron microscopy and X-ray diffraction analysis that the coated Ag layer transfers to the Sn core via diffusion to form an Ag3Sn phase at room temperature. Differential scanning calorimetry also revealed that the synthesized Sn@Ag powder is nearly transformed into Sn-3.5Ag eutectic alloy powder upon annealing three times at a temperature of up to 250 degrees C, as evidenced by a single melting peak at 220.5 degrees C. It was inferred from this that Sn-3.5Ag eutectic alloy powder can be successfully prepared through the synthesis of core Sn powders by a modified polyol method, immersion plating using citric acid, and annealing, in that order.

  4. N/P re-mineralization ratios across forests worldwide

    NASA Astrophysics Data System (ADS)

    Marklein, A. R.; Houlton, B. Z.

    2012-12-01

    Decomposition of leaf litter is the primary mechanism by which nutrients are recycled in forests. Forests are a sink for atmospheric CO2, but nitrogen (N) and phosphorus (P) could limit or eliminate this ecosystem service in the future. Nutrient cycling during mineralization supplies the vast majority of nutrients to enable forest growth. Therefore, elucidating patterns by which organic N and P are mineralized by decomposing organisms or immobilized in microbial biomass is crucial to establishing controls on plant nutrient availability. Here, we compare re-mineralization N/P ratios to the stoichiometry of the initial material. We performed a meta-analysis of N and P mineralization from leaves and needles in forest ecosystems and included 112 studies, 511 litterbag sequences, and 3225 observations. Of the compiled data, net mineralization occurred in 54 studies, 372 litterbag sequences, and 1308 observations. We compare re-mineralization ratios across temperate and tropical forest systems to elucidate patterns across latitudes. We report strong and systematic regularities between decomposing litter N/P and the N/P of re-mineralization across global forests. Overall, the N/P of mineralization scales at a slope close to unity (slope = 1.4, R2=0.53, n=372), with a tendency toward higher N/P in tropical vs. temperate forests. The N/P of tropical forest re-mineralization is equal to 30/1 (R2=0.55; n=691), corresponding with the high N/P of plant foliage and litter within this biome. In contrast, the N/P of mineralization is equal to 5/1 in temperate forests (R2=0.34; n=617). A modal anomaly analysis further reveals the central tendency of mineralization N/P on that of litter, with departures from the average case tending toward a lower N/P of mineralization compared to litter substrates. These deviations suggest the potential for preferential N retention or enhanced P mineralization, or both, as opposed to more rapid N releases from decomposing organic matter. The

  5. Adsorbate-Induced Segregation in a PdAg Membrane Model System: Pd3Ag(1 1 1)

    SciTech Connect

    Svenum, I. H.; Herron, Jeffrey A.; Mavrikakis, Manos; Venvik, H. J.

    2012-10-15

    Thin PdAg alloy membranes with 20–25% Ag are being developed for hydrogen separation technology. Despite many investigations on such membranes as well as representative experimental and theoretical model systems, unresolved issues remain concerning the effect of the alloy surface structure and composition on adsorption and vice versa. Therefore, the interaction between hydrogen, carbon monoxide or oxygen with the surface of a PdAg model alloy was studied using periodic self-consistent density functional theory (DFT-GGA) calculations. In particular, the adsorption structure, coverage dependence and possible adsorption-induced segregation phenomena were addressed using Pd3Ag(1 1 1) model surfaces with varying degrees of surface segregation. In agreement with previous experimental and theoretical investigations, we predict Ag surface termination to be energetically favorable in vacuum. The segregation of Ag is then reversed upon adsorption of H, CO or O. For these adsorbates, the binding is strongest on Pd three-fold hollow sites, and hence complete Pd termination is favored at high coverage of H or CO, while 25% Ag may remain under oxygen because of the lower O-saturation coverage. CO adsorption provides a somewhat stronger driving force for Pd segregation when compared to H, and this may have implications with respect to permeation properties of PdAg alloy surfaces. Our predictions for high coverage are particularly relevant in underlining the importance of segregation phenomena to the hydrogen transport properties of thin PdAg alloy membranes.

  6. Theoretical study of the electronic spectra of neutral and cationic NpO and NpO{sub 2}

    SciTech Connect

    Kovács, Attila; Infante, Ivan

    2015-08-21

    The electronic spectra of neutral NpO and NpO{sub 2} as well as of their mono- (NpO{sup +}, NpO{sub 2}{sup +}) and dications (NpO{sup 2+}, NpO{sub 2}{sup 2+}) were studied using multiconfigurational relativistic quantum chemical calculations at the complete active space self-consistent field/CASPT2 level of theory taking into account spin-orbit coupling. The active space included 16 orbitals: all the 7s, 6d, and 5f orbitals of neptunium together with selected orbitals of oxygen. The vertical excitation energies on the ground state geometries have been computed up to ca. 35 000 cm{sup −1}. The gas-phase electronic spectra were evaluated on the basis of the computed Einstein coefficients at 298 K and 3000 K. The computed vertical transition energies show good agreement with previous condensed-phase results on NpO{sub 2}{sup +} and NpO{sub 2}{sup 2+}.

  7. Quantum-mechanical evaluation of Np-incorporation into studtite

    SciTech Connect

    Shuller, Lindsay C.; Ewing, Rodney C.; Becker, Udo

    2010-08-05

    Radionuclide incorporation into the alteration products of corroded UO2 in used nuclear fuel may control the release and mobility of key radionuclides, such as the very long-lived minor actinide, 237Np½ = 2.1 Ma). Studtite, [UO2(O2)(H2O)2](H2O)2, may form in the presence of peroxide produced by radiolysis of water in contact with the spent fuel. Experiments have indicated that the studtite structure can incorporate Np; however, due to the low concentrations in the solid, the incorporation mechanism could not be determined. In this study, density functional theory is used to calculate an optimized structure, determine the electronic density of states, and calculate the energetics of the incorporation of Np 6+ vs. Np5++H+ into the studtite structure. The definition of the source/sink phase (reference phase) for the cations involved in the incorporation process greatly affects the final incorporation energy. The incorporation energy of Np into studtite based on the 4+ oxide reference phases (e.g., source/sink = NpO2/UO2) results in lower incorporation energies (-0.07 and 0.63 eV for Np6+ and Np5+ incorporation, respectively) than the incorporation energy calculated using higher-oxide reference phases (e.g., Np2O5/UO3), where the incorporation energies for Np5+ and Np5+ into studtite are 0.42 and 1.12 eV, respectively. In addition, Np6+-incorporation into studtite is energetically more favorable than Np5+-incorporation as assessed from the lower incorporation energy. Estimates of the solid-solution behavior from a combination of quantum-mechanical calculations and Monte-Carlo simulations indicate that the Np6+- and U6+-studtite solid solution is completely miscible at room temperature with

  8. Resonant surface enhancement of Raman scattering of Ag nanoparticles on silicon substrates fabricated by dc sputtering

    SciTech Connect

    Fang Yingcui; Li Xiaxi; Blinn, Kevin; Mahmoud, Mahmoud A.; Liu Meilin

    2012-09-15

    Ag nanoparticles (AgNPs) were deposited onto silicon substrates by direct current (dc) magnetron sputtering. The influences of sputtering power and sputtering time on the AgNP film morphology were studied using atomic force microscopy. The particle size was successfully tuned from 19 nm to 53 nm by varying the sputtering time at a dc power of 10 W. When Rhodamine 6 G (R6G) was used as the probe molecule, the AgNP films showed significant surface enhanced Raman scattering effect. In particular, it is found that larger particles show stronger enhancement for lower concentrations of R6G while smaller particles display stronger enhancement for higher concentrations of R6G.

  9. Materials Data on NpAgSeO5 (SG:2) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

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

    PubMed

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

    2015-08-01

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

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

    SciTech Connect

    Shuller, Lindsay; Ewing, Rodney C. |; Becker, Udo

    2007-07-01

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

  12. Thermal durability of AZO/Ag(Al)/AZO transparent conductive films

    NASA Astrophysics Data System (ADS)

    Sugimoto, Yukiko; Igarashi, Kanae; Shirasaki, Shinya; Kikuchi, Akihiko

    2016-04-01

    Effects of Al doping on surface morphology, sheet resistance, optical transmission spectra, and thermal durability of a thin Ag layer and AZO/Ag/AZO dielectric/metal/dielectric (DMD) transparent conductive films (TCFs) were investigated. The 1.7 at. % Al doping suppressed the initial island growth of a thin Ag layer and the plasmon resonant absorption dip in the optical transmission spectra. The threshold thickness of percolation conductivity was reduced from 9-10 (pure Al layer) to 5-6 nm (1.7 at. % Al-doped Ag layer). Al doping in the Ag layer improved the thermal durability of AZO/Ag/AZO-DMD TCFs. The threshold temperature for Ag void formation increased from 400 °C (DMD with pure Ag layer) to 600 °C (DMD with a 10.5 at. % Al-doped Ag layer). The optimum annealing temperature increased from 300 °C (DMD with a pure Ag layer) to 500 °C (DMD with a 10.5 at. % Al-doped Ag layer). Maximum figures of merit (FOM) were 0.5 × 10-2 and 1.1 × 10-2 Ω-1 for the DMD with a pure Ag layer and that with a 10.5 at. % Al-doped Ag layer, respectively.

  13. Particle placement and sheet topological control in the fabrication of Ag-hexaniobate nanocomposites.

    PubMed

    Adireddy, Shiva; Rostamzadeh, Taha; Carbo, Cecilia E; Wiley, John B

    2015-01-01

    Synthetic methods are demonstrated that allow for the fabrication of Ag-hexaniobate nanocomposites with directed nanoparticle (NP) placement and nanosheet morphological control. The solvothermal treatment of exfoliated nanosheets (NSs) in the presence of Ag NPs leads to a high yield of Ag nanocomposites. This approach is quite flexible and, with control of time and temperature, can be used to produce nanocomposites with specific architectures; Ag NPs can be attached to nanosheets, attached to the surfaces of nanoscrolls, or at higher temperatures, captured within nanoscrolls to form nanopeapod (NPP) structures. The decorated nanosheets and nanoscrolls show surface plasmon resonance (SPR) maxima similar to that of free Ag NPs, while the Ag NPPs exhibit a red shift of about 10 nm. PMID:25531945

  14. The influence of Ag nanoparticles on random laser from dye-doped nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Ye, Lihua; Liu, Bo; Li, Fangjie; Feng, Yangyang; Cui, Yiping; Lu, Yanqing

    2016-10-01

    The threshold energy and electric field response characteristic of random laser have been investigated in dye-doped nematic liquid crystal (DDNLC) with the addition of different concentrations of Ag nanoparticles (NPs). Due to the localized surface plasmon resonance (LSPR) induced by Ag NPs, random laser from DDNLC with Ag NP doping had a lower threshold energy. From another point of view, nematic liquid crystals (LCs) in a DDNLC cell with the addition of Ag NPs could be more easily influenced by the electric field, which allowed the random laser to be controlled at a lower applied voltage. The turn-off time and turn-on time of random laser also decreased in the DDNLC cells with increasing the concentration of Ag NPs. This is due to the enhancement of the electro-optical characteristic of LC and the restoring force imparted by the locally ordered LCs induced by the Ag NPs, respectively.

  15. Large-scale fabrication and application of magnetite coated Ag NW-core water-dispersible hybrid nanomaterials.

    PubMed

    Wang, Baoyu; Zhang, Min; Li, Weizhen; Wang, Linlin; Zheng, Jing; Gan, Wenjun; Xu, Jingli

    2015-05-01

    In this work, we report a large scale synthetic procedure that allows attachment of magnetite nanoparticles onto Ag NWs in situ, which was conducted in a triethylene glycol (TREG) solution with iron acetylacetonate and Ag NWs as starting materials. The as-prepared Ag NW/Fe3O4 NP composites are well characterized by SEM, TEM, XRD, XPS, FT-IR, and VSM techniques. It was found that the mass ratio of iron acetylacetonate to Ag NWs plays a crucial role in controlling the amount of magnetite nanoparticles decorated on the Ag NWs. The resulting Ag NW/Fe3O4 NP composites exhibit superparamagnetic properties at room temperature, and can be well dispersed in aqueous and organic solutions, which is greatly beneficial for their application and functionality. Thus, the as-prepared magnetic silver nanowires show good catalytic activity, using the catalytic reduction of methylene blue (MB) as a model reaction. Furthermore, the Ag NW/Fe3O4 NP composites can be functionalized with polydopamine (Pdop), resorcinol-formaldehyde resin (PFR), and SiO2, respectively, in aqueous/ethanol solution. Meanwhile they can also be coated with polyphosphazene (PZS) in organic solution, resulting in a unique nanocable with well-defined core shell structures. Besides, taking Ag NW/Fe3O4@SiO2 as an example, a hollow magnetic silica nanotube can be obtained with the use of Ag NWs as physical templates and a solution of ammonium and H2O2. These can greatly improve the application of the Ag NW/Fe3O4 NP composites. The as-synthesized above nanocomposites have high potential for applications in the fields of polymers, wastewater treatment, sensors, and biomaterials.

  16. Large-scale fabrication and application of magnetite coated Ag NW-core water-dispersible hybrid nanomaterials.

    PubMed

    Wang, Baoyu; Zhang, Min; Li, Weizhen; Wang, Linlin; Zheng, Jing; Gan, Wenjun; Xu, Jingli

    2015-05-01

    In this work, we report a large scale synthetic procedure that allows attachment of magnetite nanoparticles onto Ag NWs in situ, which was conducted in a triethylene glycol (TREG) solution with iron acetylacetonate and Ag NWs as starting materials. The as-prepared Ag NW/Fe3O4 NP composites are well characterized by SEM, TEM, XRD, XPS, FT-IR, and VSM techniques. It was found that the mass ratio of iron acetylacetonate to Ag NWs plays a crucial role in controlling the amount of magnetite nanoparticles decorated on the Ag NWs. The resulting Ag NW/Fe3O4 NP composites exhibit superparamagnetic properties at room temperature, and can be well dispersed in aqueous and organic solutions, which is greatly beneficial for their application and functionality. Thus, the as-prepared magnetic silver nanowires show good catalytic activity, using the catalytic reduction of methylene blue (MB) as a model reaction. Furthermore, the Ag NW/Fe3O4 NP composites can be functionalized with polydopamine (Pdop), resorcinol-formaldehyde resin (PFR), and SiO2, respectively, in aqueous/ethanol solution. Meanwhile they can also be coated with polyphosphazene (PZS) in organic solution, resulting in a unique nanocable with well-defined core shell structures. Besides, taking Ag NW/Fe3O4@SiO2 as an example, a hollow magnetic silica nanotube can be obtained with the use of Ag NWs as physical templates and a solution of ammonium and H2O2. These can greatly improve the application of the Ag NW/Fe3O4 NP composites. The as-synthesized above nanocomposites have high potential for applications in the fields of polymers, wastewater treatment, sensors, and biomaterials. PMID:25815705

  17. Ag(I)-triggered one-pot synthesis of Ag nanoparticles onto natural nanorods as a multifunctional nanocomposite for efficient catalysis and adsorption.

    PubMed

    Tian, Guangyan; Wang, Wenbo; Mu, Bin; Kang, Yuru; Wang, Aiqin

    2016-07-01

    A multifunctional palygorskite/polyaniline/Ag nanoparticles (PAL/PANI/AgNPs) nanocomposite was prepared at room temperature using a simple one-pot in-situ polymerization reaction of aniline monomers triggered by Ag(I) on the surface of natural PAL nanorods. Ag(I) served as both the oxidant and the precursor of the AgNPs, which initiated the polymerization of aniline monomers on PAL nanorods while simultaneously being reduced to form Ag(0) nanoparticles (AgNPs). The in-situ formed AgNPs were evenly distributed on the surface of the PAL nanorods because the interfacial effect of PAL prevents their aggregation. The density and size of the AgNPs and the catalytic activity of the nanocomposites could be controlled by altering the molar ratio of aniline to Ag(I). The performance evaluation revealed that the nanocomposites could be used as highly active catalysts, which rapidly catalyzed the reduction of 4-nitrophenol (4-NP) within 2min and Congo red (CR) within 10min. The nanocomposites are also an effective adsorbent for H2PO4(-) able to remove 99.40% of H2PO4(-) (only 61.77% for raw PAL) from a solution with an initial concentration of 50mg/L. This multifunctional nanocomposite synthesized by a simple one-pot approach is a promising material for environmental applications.

  18. Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites.

    PubMed

    Prakash, Jai; Kumar, Promod; Harris, R A; Swart, Chantel; Neethling, J H; van Vuuren, A Janse; Swart, H C

    2016-09-01

    We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples. PMID:27456278

  19. Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites

    NASA Astrophysics Data System (ADS)

    Prakash, Jai; Kumar, Promod; Harris, R. A.; Swart, Chantel; Neethling, J. H.; Janse van Vuuren, A.; Swart, H. C.

    2016-09-01

    We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples.

  20. Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites.

    PubMed

    Prakash, Jai; Kumar, Promod; Harris, R A; Swart, Chantel; Neethling, J H; van Vuuren, A Janse; Swart, H C

    2016-09-01

    We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples.

  1. Ag Nanoparticles (Ag NM300K) in the Terrestrial Environment: Effects at Population and Cellular Level in Folsomia candida (Collembola)

    PubMed Central

    Mendes, Luís André; Maria, Vera L.; Scott-Fordsmand, Janeck J.; Amorim, Mónica J. B.

    2015-01-01

    The effects of nanomaterials have been primarily assessed based on standard ecotoxicity guidelines. However, by adapting alternative measures the information gained could be enhanced considerably, e.g., studies should focus on more mechanistic approaches. Here, the environmental risk posed by the presence of silver nanoparticles (Ag NM300K) in soil was investigated, anchoring population and cellular level effects, i.e., survival, reproduction (28 days) and oxidative stress markers (0, 2, 4, 6, 10 days). The standard species Folsomia candida was used. Measured markers included catalase (CAT), glutathione reductase (GR), glutathione S-transferase (GST), total glutathione (TG), metallothionein (MT) and lipid peroxidation (LPO). Results showed that AgNO3 was more toxic than AgNPs at the population level: reproduction EC20 and EC50 was ca. 2 and 4 times lower, respectively. At the cellular level Correspondence Analysis showed a clear separation between AgNO3 and AgNP throughout time. Results showed differences in the mechanisms, indicating a combined effect of released Ag+ (MT and GST) and of AgNPs (CAT, GR, TG, LPO). Hence, clear advantages from mechanistic approaches are shown, but also that time is of importance when measuring such responses. PMID:26473892

  2. Natural water as the test medium for Ag and CuO nanoparticle hazard evaluation: An interlaboratory case study.

    PubMed

    Heinlaan, Margit; Muna, Marge; Knöbel, Melanie; Kistler, David; Odzak, Niksa; Kühnel, Dana; Müller, Josefine; Gupta, Govind Sharan; Kumar, Ashutosh; Shanker, Rishi; Sigg, Laura

    2016-09-01

    Engineered nanoparticles (NPs) have realistic potential of reaching natural waterbodies and of exerting toxicity to freshwater organisms. The toxicity may be influenced by the composition of natural waters as crucial NP properties are influenced by water constituents. To tackle this issue, a case study was set up in the framework of EU FP7 NanoValid project, performing an interlaboratory hazard evaluation of NPs in natural freshwater. Ag and CuO NPs were selected as model NPs because of their potentially high toxicity in the freshwater. Daphnia magna (OECD202) and Danio rerio embryo (OECD236) assays were used to evaluate NP toxicity in natural water, sampled from Lake Greifen and Lake Lucerne (Switzerland). Dissolution of the NPs was evaluated by ultrafiltration, ultracentrifugation and metal specific sensor bacteria. Ag NP size was stable in natural water while CuO NPs agglomerated and settled rapidly. Ag NP suspensions contained a large fraction of Ag(+) ions and CuO NP suspensions had low concentration of Cu(2+) ions. Ag NPs were very toxic (48 h EC50 1-5.5 μg Ag/L) to D. magna as well as to D. rerio embryos (96 h EC50 8.8-61 μg Ag/L) in both standard media and natural waters with results in good agreement between laboratories. CuO NP toxicity to D. magna differed significantly between the laboratories with 48 h EC50 0.9-11 mg Cu/L in standard media, 5.7-75 mg Cu/L in Lake Greifen and 5.5-26 mg Cu/L in Lake Lucerne. No toxicity of CuO NP to zebrafish embryos was detected up to 100 mg/L independent of the medium used. The results show that Ag and CuO NP toxicity may be higher in natural water than in the standard media due to differences in composition. NP environmental hazard evaluation can and should be carried out in natural water to obtain more realistic estimates on the toxicity.

  3. Natural water as the test medium for Ag and CuO nanoparticle hazard evaluation: An interlaboratory case study.

    PubMed

    Heinlaan, Margit; Muna, Marge; Knöbel, Melanie; Kistler, David; Odzak, Niksa; Kühnel, Dana; Müller, Josefine; Gupta, Govind Sharan; Kumar, Ashutosh; Shanker, Rishi; Sigg, Laura

    2016-09-01

    Engineered nanoparticles (NPs) have realistic potential of reaching natural waterbodies and of exerting toxicity to freshwater organisms. The toxicity may be influenced by the composition of natural waters as crucial NP properties are influenced by water constituents. To tackle this issue, a case study was set up in the framework of EU FP7 NanoValid project, performing an interlaboratory hazard evaluation of NPs in natural freshwater. Ag and CuO NPs were selected as model NPs because of their potentially high toxicity in the freshwater. Daphnia magna (OECD202) and Danio rerio embryo (OECD236) assays were used to evaluate NP toxicity in natural water, sampled from Lake Greifen and Lake Lucerne (Switzerland). Dissolution of the NPs was evaluated by ultrafiltration, ultracentrifugation and metal specific sensor bacteria. Ag NP size was stable in natural water while CuO NPs agglomerated and settled rapidly. Ag NP suspensions contained a large fraction of Ag(+) ions and CuO NP suspensions had low concentration of Cu(2+) ions. Ag NPs were very toxic (48 h EC50 1-5.5 μg Ag/L) to D. magna as well as to D. rerio embryos (96 h EC50 8.8-61 μg Ag/L) in both standard media and natural waters with results in good agreement between laboratories. CuO NP toxicity to D. magna differed significantly between the laboratories with 48 h EC50 0.9-11 mg Cu/L in standard media, 5.7-75 mg Cu/L in Lake Greifen and 5.5-26 mg Cu/L in Lake Lucerne. No toxicity of CuO NP to zebrafish embryos was detected up to 100 mg/L independent of the medium used. The results show that Ag and CuO NP toxicity may be higher in natural water than in the standard media due to differences in composition. NP environmental hazard evaluation can and should be carried out in natural water to obtain more realistic estimates on the toxicity. PMID:27357482

  4. Ferro- and antiferro-magnetism in (Np, Pu)BC

    SciTech Connect

    Klimczuk, T.; Kozub, A. L.; Griveau, J.-C.; Colineau, E.; Wastin, F.; Falmbigl, M.; Rogl, P.

    2015-04-01

    Two new transuranium metal boron carbides, NpBC and PuBC, have been synthesized. Rietveld refinements of powder XRD patterns of (Np,Pu)BC confirmed in both cases isotypism with the structure type of UBC. Temperature dependent magnetic susceptibility data reveal antiferromagnetic ordering for PuBC below T{sub N} = 44 K, whereas ferromagnetic ordering was found for NpBC below T{sub C} = 61 K. Heat capacity measurements prove the bulk character of the observed magnetic transition for both compounds. The total energy electronic band structure calculations support formation of the ferromagnetic ground state for NpBC and the antiferromagnetic ground state for PuBC.

  5. Evaluation of Postharvest Washing on Removal of Silver Nanoparticles (AgNPs) from Spinach Leaves.

    PubMed

    Zhang, Zhiyun; Guo, Huiyuan; Carlisle, Thomas; Mukherjee, Arnab; Kinchla, Amanda; White, Jason C; Xing, Baoshan; He, Lili

    2016-09-21

    There is increasing use of silver nanoparticles (AgNPs) as pesticides for fruits and vegetables due to the particles' unique antimicrobial and insecticidal properties. However, residual AgNPs in harvested produce may transfer through the food chain and pose a potential risk to public health. The objective of this study is to determine whether postharvest washing can effectively remove AgNPs that had accumulated on fresh produce. Ten microliters of commercially available 40 nm citrate coated AgNPs (0.4 mg/L) was dropped to a (1 × 1 cm(2)) spot on spinach leaves, followed by washing with deionized water (DI water), Tsunami 100 (80 mg/L), or Clorox bleach (200 mg/L). Then, the AgNP removal efficiency of the three treatments was evaluated by surface-enhanced Raman spectroscopy (SERS), scanning electron microscopy (SEM)-energy dispersive spectrometry (EDS), and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS results showed that deionized water removed statistically insignificant amounts of total Ag (5%), whereas Tsunami 100 and Clorox bleach yielded 21 and 10% decreases in total Ag, respectively (P < 0.05). The increased removal efficiency resulted from AgNP dissolution and Ag(+) release upon contact with the oxidizing agents in Tsunami 100 (peroxyacetic acid, hydrogen peroxide) and Clorox bleach (sodium hypochlorite). According to the SERS results, the deionized water and Tsunami 100 treatments removed nonsignificant amounts of AgNPs. Clorox bleach decreased Ag NPs by >90% (P < 0.05); however, SEM-EDS images revealed the formation of large silver chloride (AgCl) crystals (162 ± 51 nm) on the leaf, which explained the low total Ag removal from ICP-MS. This study indicates current factory washing methods for fresh produce may not be effective in reducing AgNPs (by water and Tsunami 100) and total Ag (by all three means). This highlights the necessity to develop an efficient washing method for NP removal from food surfaces in the future. PMID:27548506

  6. Evaluation of Postharvest Washing on Removal of Silver Nanoparticles (AgNPs) from Spinach Leaves.

    PubMed

    Zhang, Zhiyun; Guo, Huiyuan; Carlisle, Thomas; Mukherjee, Arnab; Kinchla, Amanda; White, Jason C; Xing, Baoshan; He, Lili

    2016-09-21

    There is increasing use of silver nanoparticles (AgNPs) as pesticides for fruits and vegetables due to the particles' unique antimicrobial and insecticidal properties. However, residual AgNPs in harvested produce may transfer through the food chain and pose a potential risk to public health. The objective of this study is to determine whether postharvest washing can effectively remove AgNPs that had accumulated on fresh produce. Ten microliters of commercially available 40 nm citrate coated AgNPs (0.4 mg/L) was dropped to a (1 × 1 cm(2)) spot on spinach leaves, followed by washing with deionized water (DI water), Tsunami 100 (80 mg/L), or Clorox bleach (200 mg/L). Then, the AgNP removal efficiency of the three treatments was evaluated by surface-enhanced Raman spectroscopy (SERS), scanning electron microscopy (SEM)-energy dispersive spectrometry (EDS), and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS results showed that deionized water removed statistically insignificant amounts of total Ag (5%), whereas Tsunami 100 and Clorox bleach yielded 21 and 10% decreases in total Ag, respectively (P < 0.05). The increased removal efficiency resulted from AgNP dissolution and Ag(+) release upon contact with the oxidizing agents in Tsunami 100 (peroxyacetic acid, hydrogen peroxide) and Clorox bleach (sodium hypochlorite). According to the SERS results, the deionized water and Tsunami 100 treatments removed nonsignificant amounts of AgNPs. Clorox bleach decreased Ag NPs by >90% (P < 0.05); however, SEM-EDS images revealed the formation of large silver chloride (AgCl) crystals (162 ± 51 nm) on the leaf, which explained the low total Ag removal from ICP-MS. This study indicates current factory washing methods for fresh produce may not be effective in reducing AgNPs (by water and Tsunami 100) and total Ag (by all three means). This highlights the necessity to develop an efficient washing method for NP removal from food surfaces in the future.

  7. AGS experiments - 1994, 1995, 1996

    SciTech Connect

    Depken, J.C.

    1997-01-01

    This report contains the following information on the Brookhaven AGS Accelerator complex: FY 1996 AGS schedule as run; FY 1997 AGS schedule (working copy); AGS beams 1997; AGS experimental area FY 1994 physics program; AGS experimental area FY 1995 physics program; AGS experimental area FY 1996 physics program; AGS experimental area FY 1997 physics program (in progress); a listing of experiments by number; two-phage summaries of each experiment begin here, also ordered by number; listing of publications of AGS experiments begins here; and listing of AGS experimenters begins here.

  8. Performance and temperature dependencies of proton irradiated n/p GaAs and n/p silicon cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.

    1985-01-01

    The n/p homojunction GaAs cell is found to be more radiation resistant than p/nheteroface GaAs under 10 MeV proton irradiation. Both GaAs cell types outperform conventional silicon n/p cells under the same conditions. An increase temperature dependency of maximum power for the GaAs n/p cells is attributed largely to differences in Voc between the two GaAs cell types. These results and diffusion length considerations are consistent with the conclusion that p-type GaAs is more radiation resistant than n-type and therefore that the n/p configuration is possibly favored for use in the space radiation environment. However, it is concluded that additional work is required in order to choose between the two GaAs cell configurations.

  9. TCO/Ag/TCO transparent electrodes for solar cells application

    NASA Astrophysics Data System (ADS)

    Boscarino, S.; Crupi, I.; Mirabella, S.; Simone, F.; Terrasi, A.

    2014-09-01

    Among transparent electrodes, transparent conductive oxides (TCO)/metal/TCO structures can achieve optical and electrical performances comparable to, or better than, single TCO layers and very thin metallic films. In this work, we report on thin multilayers based on aluminum zinc oxide (AZO), indium tin oxide (ITO) and Ag deposited by RF magnetron sputtering on soda lime glass at room temperature. The TCO/Ag/TCO structures with thicknesses of about 50/10/50 nm were deposited with all combinations of AZO and ITO as top and bottom layers. While the electrical conductivity is dominated by the Ag intralayer irrespective of the TCO nature, the optical transmissions show a dependence on the nature of the top and bottom TCOs, mainly due to the change in the reflectivity of the multilayers. Structural, electrical and optical properties are studied to optimize the structure for very thin transparent electrodes suitable for photovoltaic applications.

  10. Microstructure and thermal conduction properties of Al{sub 2}O{sub 3}-Ag composites

    SciTech Connect

    Liu, D.M.; Tuan, W.H.

    1996-02-01

    Microstructure and thermal conduction properties involving thermal diffusivity and conductivity of composite, Al{sub 2}O{sub 3}-Ag, were investigated. The Ag particles observed in the composites were spread sporadically throughout the composite with inclusion size increasing with Ag content, rather than forming a network of thin film foil. Thermal conductivity of the composite increased with Ag content and followed composite theory prediction with a negligible influence of interfacial contact resistance. The temperature dependence of the thermal conductivity became less pronounced with increasing Ag content reflecting the nature of electron contribution in Ag rather than the typical phonon contribution in polycrystalline Al{sub 2}O{sub 3}. The lower composite conductivity at higher Ag contents as compared to theoretical predictions is due primarily to the residual pore phase, associated with the cavity formation for the composite containing 10 vol.% Ag.

  11. Structural, electronic, and magnetic characteristics of Np2Co17

    NASA Astrophysics Data System (ADS)

    Halevy, I.; Hen, A.; Orion, I.; Colineau, E.; Eloirdi, R.; Griveau, J.-C.; Gaczyński, P.; Wilhelm, F.; Rogalev, A.; Sanchez, J.-P.; Winterrose, M. L.; Magnani, N.; Shick, A. B.; Caciuffo, R.

    2012-01-01

    A previously unknown neptunium-transition-metal binary compound Np2Co17 has been synthesized and characterized by means of powder x-ray diffraction, 237Np Mössbauer spectroscopy, superconducting-quantum-interference-device magnetometry, and x-ray magnetic circular dichroism (XMCD). The compound crystallizes in a Th2Ni17-type hexagonal structure with room-temperature lattice parameters a=8.3107(1) Å and c=8.1058(1) Å. Magnetization curves indicate the occurrence of ferromagnetic order below TC>350 K. Mössbauer spectra suggest a Np3+ oxidation state and give an ordered moment of μNp=1.57(4) μB and μNp=1.63(4) μB for the Np atoms located, respectively, at the 2b and 2d crystallographic positions of the P63/mmc space group. Combining these values with a sum-rule analysis of the XMCD spectra measured at the neptunium M4,5 absorption edges, one obtains the spin and orbital contributions to the site-averaged Np moment [μS=-1.88(9) μB, μL=3.48(9) μB]. The ratio between the expectation value of the magnetic-dipole moment and the spin magnetic moment (mmd/μS=+1.36) is positive as predicted for localized 5f electrons and lies between the values calculated in intermediate-coupling (IC) and jj approximations. The expectation value of the angular part of the spin-orbit-interaction operator is in excellent agreement with the IC estimate. The ordered moment averaged over the four inequivalent Co sites, as obtained from the saturation value of the magnetization, is μCo≃1.6 μB. The experimental results are discussed against the predictions of first-principles electronic-structure calculations based on the spin-polarized local-spin-density approximation plus the Hubbard interaction.

  12. Silver nanoparticles (AgNPs) cause degeneration of cytoskeleton and disrupt synaptic machinery of cultured cortical neurons

    PubMed Central

    2013-01-01

    Background Silver nanoparticles (AgNPs), owing to their effective antimicrobial properties, are being widely used in a broad range of applications. These include, but are not limited to, antibacterial materials, the textile industry, cosmetics, coatings of various household appliances and medical devices. Despite their extensive use, little is known about AgNP safety and toxicity vis-à-vis human and animal health. Recent studies have drawn attention towards potential neurotoxic effects of AgNPs, however, the primary cellular and molecular targets of AgNP action/s remain to be defined. Results Here we examine the effects of ultra fine scales (20 nm) of AgNPs at various concentrations (1, 5, 10 and 50 μg/ml) on primary rat cortical cell cultures. We found that AgNPs (at 1-50 μg/ml) not only inhibited neurite outgrowth and reduced cell viability of premature neurons and glial cells, but also induced degeneration of neuronal processes of mature neurons. Our immunocytochemistry and confocal microscopy studies further demonstrated that AgNPs induced the loss of cytoskeleton components such as the β-tubulin and filamentous actin (F-actin). AgNPs also dramatically reduced the number of synaptic clusters of the presynaptic vesicle protein synaptophysin, and the postsynaptic receptor density protein PSD-95. Finally, AgNP exposure also resulted in mitochondria dysfunction in rat cortical cells. Conclusions Taken together, our data show that AgNPs induce toxicity in neurons, which involves degradation of cytoskeleton components, perturbations of pre- and postsynaptic proteins, and mitochondrial dysfunction leading to cell death. Our study clearly demonstrates the potential detrimental effects of AgNPs on neuronal development and physiological functions and warns against its prolific usage. PMID:23782671

  13. Highly active Ag clusters stabilized on TiO2 nanocrystals for catalytic reduction of p-nitrophenol

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Zhao, Zhe; Ou, Dingrong; Tu, Baofeng; Cui, Daan; Wei, Xuming; Cheng, Mojie

    2016-11-01

    Ag/TiO2 nanocomposites comprising of Ag clusters on TiO2 nanocrystal surfaces are of great significance in catalysts and advanced functional materials. Herein a novel method to synthesize Ag/TiO2 nanocomposites with Ag clusters under 2 nm on TiO2 nanocrystal surfaces have been developed. The success of this method relies on a silver mirror reaction in toluene, which refers to the reduction of silver-dodecylamine complexes by acetaldehyde in the presence of mono-dispersed TiO2 nanocrystals. The prepared Ag/TiO2 nanocomposites have been characterized by FT-IR spectra, UV-vis absorption spectra, X-ray diffraction (XRD) analysis, ultra high resolution scanning electron microscope (Ultra-HRSEM), high resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectra (XPS). Catalytic activity of Ag/TiO2 nanocomposites is evaluated for the reduction of p-nitrophenol (4-NP) into p-aminophenol (4-AP) by NaBH4. Results demonstrate that Ag/TiO2 nanocomposites have shown an outstanding catalytic activity as well as a good stability in successive reduction of 4-NP. Noticeably, TOF of Ag/TiO2-0.75 nanocomposites obtained in this work is the highest among Ag based catalysts previously reported.

  14. In Situ Localized Surface Plasmon Resonance (LSPR) Spectroscopy to Investigate Kinetics of Chemical Bath Deposition of CdS Thin Films

    SciTech Connect

    Kalyanaraman, Ramki; Taz, Humaira; Ruther, Rose E.; Nanda, Jagjit

    2015-02-11

    Techniques that can characterize the early stages of thin film deposition from liquid phase processes can aid greatly in our understanding of mechanistic aspects of chemical bath deposition (CBD). Here we have used localized surface plasmon resonance (LSPR) spectroscopy to monitor in-situ the kinetics of early-stage growth of cadmium sulfide (CdS) thin films on Ag nanoparticle on quartz substrates. Real-time shift during CdS deposition showed that the LSPR wavelength red shifted rapidly due to random deposition of CdS on the substrate, but saturated at longer times. LSPR modeling showed that these features could be interpreted as an initial deposition of CdS islands followed by preferential deposition onto itself. The CdS also showed significantly enhanced Raman signals up to 170 times due to surface enhanced raman scattering (SERS) from the CdS/Ag NP regions. The ex-situ SERS effect supported the LSPR shift suggesting that these techniques could be used to understand nucleation and growth phenomena from the liquid phase.

  15. In Situ Localized Surface Plasmon Resonance (LSPR) Spectroscopy to Investigate Kinetics of Chemical Bath Deposition of CdS Thin Films

    DOE PAGES

    Kalyanaraman, Ramki; Taz, Humaira; Ruther, Rose E.; Nanda, Jagjit

    2015-02-11

    Techniques that can characterize the early stages of thin film deposition from liquid phase processes can aid greatly in our understanding of mechanistic aspects of chemical bath deposition (CBD). Here we have used localized surface plasmon resonance (LSPR) spectroscopy to monitor in-situ the kinetics of early-stage growth of cadmium sulfide (CdS) thin films on Ag nanoparticle on quartz substrates. Real-time shift during CdS deposition showed that the LSPR wavelength red shifted rapidly due to random deposition of CdS on the substrate, but saturated at longer times. LSPR modeling showed that these features could be interpreted as an initial deposition ofmore » CdS islands followed by preferential deposition onto itself. The CdS also showed significantly enhanced Raman signals up to 170 times due to surface enhanced raman scattering (SERS) from the CdS/Ag NP regions. The ex-situ SERS effect supported the LSPR shift suggesting that these techniques could be used to understand nucleation and growth phenomena from the liquid phase.« less

  16. Parity-Violating Interaction Effects in the np System

    SciTech Connect

    R. Schiavilla; J.A. Carlson; M. Paris

    2003-09-03

    We investigate parity-violating observables in the np system, including the longitudinal asymmetry and neutron-spin rotation in np elastic scattering, the photon asymmetry in np radiative capture, and the asymmetries in deuteron photo-disintegration d(gamma,n)p in the threshold region and electro-disintegration d(e,e`)np in quasi-elastic kinematics. To have an estimate of the model dependence for the various predictions, a number of different, latest-generation strong-interaction potentials--Argonne v18, Bonn 2000, and Nijmegen I--are used in combination with a weak-interaction potential consisting of pi-, rho-, and omega-meson exchanges--the model known as DDH. The complete bound and scattering problems in the presence of parity-conserving, including electromagnetic, and parity-violating potentials is solved in both configuration and momentum space. The issue of electromagnetic current conservation is examined carefully. We find large cancellations between the asymmetries induced by the parity-violating interactions and those arising from the associated pion-exchange currents. In the np capture, the model dependence is nevertheless quite small, because of constraints arising through the Siegert evaluation of the relevant E1 matrix elements. In quasi-elastic electron scattering these processes are found to be insignificant compared to the asymmetry produced by gamma-Z interference on individual nucleons.

  17. Unusual behaviour of (Np,Pu)B2C

    NASA Astrophysics Data System (ADS)

    Klimczuk, Tomasz; Boulet, Pascal; Griveau, Jean-Christophe; Colineau, Eric; Bauer, Ernst; Falmbigl, Matthias; Rogl, Peter; Wastin, Franck

    2015-02-01

    Two transuranium metal boron carbides, NpB2C and PuB2C have been synthesized by argon arc melting. The crystal structures of the {Np,Pu}B2C compounds were determined from single-crystal X-ray data to be isotypic with the ThB2C-type (space group ?, a = 0.6532(2) nm; c = 1.0769(3) nm for NpB2C and a = 0.6509(2) nm; c = 1.0818(3) nm for PuB2C; Z = 9). Physical properties have been derived from polycrystalline bulk material in the temperature range from 2 to 300 K and in magnetic fields up to 9 T. Magnetic susceptibility and heat capacity data indicate the occurrence of antiferromagnetic ordering for NpB2C with a Neel temperature TN = 68 K. PuB2C is a Pauli paramagnet most likely due to a strong hybridization of s(p,d) electrons with the Pu-5f states. A pseudo-gap, as concluded from the Sommerfeld value and the electronic transport, is thought to be a consequence of the hybridization. The magnetic behaviour of {Np,Pu}B2C is consistent with the criterion of Hill.

  18. Properties of MgB2 films deposited on single crystal Ag layers

    NASA Astrophysics Data System (ADS)

    Liu, Z. H.; Wei, Y. K.; Zhang, C.; Feng, Q. R.; Ma, P.; Wang, Y.

    2014-04-01

    We have recently developed a method to deposit MgB2 thin films on single crystal Ag layers, and found that thin Ag layers reduced the the superconductivity of MgB2 not much, which may be a possible material to fabricate MgB2 SNS Josephson junctions. The single crystal Ag layers were deposited on (0 0 0 1) SiC substrates, and then the MgB2 thin films were deposited on the Ag layers. All the measurements included the XRD, M-T and M-H curves. The transition temperature of MgB2 films decreases from 39 K to 37 K, while the thickness of Ag layers grows from 0 to 20 nm, and the critical current density at 4.2 K decreases from 1.76 MA/cm2 to 1.24 MA/cm2, too.

  19. Influence of Ag thickness on structural, optical, and electrical properties of ZnS/Ag/ZnS multilayers prepared by ion beam assisted deposition

    SciTech Connect

    Leng Jian; Yu Zhinong; Xue Wei; Zhang Ting; Jiang Yurong; Zhang Jie; Zhang Dongpu

    2010-10-15

    The structural, optical, and electrical characteristics of zinc sulfide (ZnS)/Ag/ZnS (ZAZ) multilayer films prepared by ion beam assisted deposition on k9 glass have been investigated as a function of Ag layer thickness. The characteristics of ZAZ multilayer are significantly improved up insertion of optimal Ag thickness between ZnS layers. The results show that due to bombardment of Ar ion beam, distinct Ag islands evolve into continuous Ag films at a thin Ag thickness of about 4 nm. The thinner Ag film as a thickness of 2 nm leads to high sheet resistance and low transmittance for the interface scattering induced by the Ag islands or noncontinuous films; and when the Ag thickness is over 4 nm, the ZAZ multilayer exhibits a remarkably reduced sheet resistance between 7-80 {Omega}/sq for the increase in carrier concentration and mobility of Ag layer, and a high transmittance over 90% for the interference phenomena of multilayers and low absorption and surface scattering of Ag layer. The ZAZ multilayer with 14 nm Ag film has a figure of merit up to 6.32x10{sup -2} {Omega}{sup -1}, an average transmittance over 92% and a sheet resistance of 7.1 {Omega}/sq. The results suggest that ZAZ film has better optoelectrical properties than conditional indium tin oxide single layer.

  20. Ag Nanoparticles (Ag NM300K) in the Terrestrial Environment: Effects at Population and Cellular Level in Folsomia candida (Collembola).

    PubMed

    Mendes, Luís André; Maria, Vera L; Scott-Fordsmand, Janeck J; Amorim, Mónica J B

    2015-10-01

    The effects of nanomaterials have been primarily assessed based on standard ecotoxicity guidelines. However, by adapting alternative measures the information gained could be enhanced considerably, e.g., studies should focus on more mechanistic approaches. Here, the environmental risk posed by the presence of silver nanoparticles (Ag NM300K) in soil was investigated, anchoring population and cellular level effects, i.e., survival, reproduction (28 days) and oxidative stress markers (0, 2, 4, 6, 10 days). The standard species Folsomia candida was used. Measured markers included catalase (CAT), glutathione reductase (GR), glutathione S-transferase (GST), total glutathione (TG), metallothionein (MT) and lipid peroxidation (LPO). Results showed that AgNO₃ was more toxic than AgNPs at the population level: reproduction EC₂₀ and EC₅₀ was ca. 2 and 4 times lower, respectively. At the cellular level Correspondence Analysis showed a clear separation between AgNO₃ and AgNP throughout time. Results showed differences in the mechanisms, indicating a combined effect of released Ag⁺ (MT and GST) and of AgNPs (CAT, GR, TG, LPO). Hence, clear advantages from mechanistic approaches are shown, but also that time is of importance when measuring such responses. PMID:26473892

  1. A comparative study about electronic structures at rubrene/Ag and Ag/rubrene interfaces

    SciTech Connect

    Sinha, Sumona Mukherjee, M.

    2015-10-15

    The contact between the electrode and the organic semiconductor is one of the most crucial factors in determining the organic device performance. The development and production technology of different organic devices require the understanding of different types of metal/organic semiconducting thin film interfaces. Comparisons about the electronic structures at Rubrene/Ag and Ag/Rubrene interfaces have been studied using photoemission spectroscopy. The Ag on rubrene interfaces is found to show more interesting and complex natures than its counterpart. The vacuum level (VL) was shifted about 0.51 eV from push back effect for deposition of 5 Å rubrene onto Ag film whereas the electronic features of silver was only suppressed and no energy shift was resulted. While the deposition of 5 Å Ag onto rubrene film leads to the diffusion of the Ag atoms, as a cluster with quantum size effect, inside the film. Angle dependent XPS measurement indicates that diffused metal clusters were present at entire probed depth of the film. Moreover these clusters dope the uppermost surface of the rubrene film which consequences a shift of the electronic states of thick organic film towards higher binding energy. The VL was found to shift about 0.31 eV toward higher binding energy whereas the shift was around 0.21 eV for the electronic states of rubrene layer.

  2. Ag induced electromagnetic interference shielding of Ag-graphite/PVDF flexible nanocomposites thinfilms

    SciTech Connect

    Kumaran, R.; Alagar, M.; Dinesh Kumar, S.; Subramanian, V.; Dinakaran, K.

    2015-09-14

    We report Ag nanoparticle induced Electromagnetic Interference (EMI) shielding in a flexible composite films of Ag nanoparticles incorporated graphite/poly-vinylidene difluoride (PVDF). PVDF nanocomposite thin-films were synthesized by intercalating Ag in Graphite (GIC) followed by dispersing GIC in PVDF. The X-ray diffraction analysis and the high-resolution transmission electron microscope clearly dictate the microstructure of silver nanoparticles in graphite intercalated composite of PVDF matrix. The conductivity values of nanocomposites are increased upto 2.5 times when compared to neat PVDF having a value of 2.70 S/cm at 1 MHz. The presence of Ag broadly enhanced the dielectric constant and lowers the dielectric loss of PVDF matrix proportional to Ag content. The EMI shielding effectiveness of the composites is 29.1 dB at 12.4 GHz for the sample having 5 wt. % Ag and 10 wt. % graphite in PVDF.

  3. A comparative study about electronic structures at rubrene/Ag and Ag/rubrene interfaces

    NASA Astrophysics Data System (ADS)

    Sinha, Sumona; Mukherjee, M.

    2015-10-01

    The contact between the electrode and the organic semiconductor is one of the most crucial factors in determining the organic device performance. The development and production technology of different organic devices require the understanding of different types of metal/organic semiconducting thin film interfaces. Comparisons about the electronic structures at Rubrene/Ag and Ag/Rubrene interfaces have been studied using photoemission spectroscopy. The Ag on rubrene interfaces is found to show more interesting and complex natures than its counterpart. The vacuum level (VL) was shifted about 0.51 eV from push back effect for deposition of 5 Å rubrene onto Ag film whereas the electronic features of silver was only suppressed and no energy shift was resulted. While the deposition of 5 Å Ag onto rubrene film leads to the diffusion of the Ag atoms, as a cluster with quantum size effect, inside the film. Angle dependent XPS measurement indicates that diffused metal clusters were present at entire probed depth of the film. Moreover these clusters dope the uppermost surface of the rubrene film which consequences a shift of the electronic states of thick organic film towards higher binding energy. The VL was found to shift about 0.31 eV toward higher binding energy whereas the shift was around 0.21 eV for the electronic states of rubrene layer.

  4. Synthesis of reduced graphene oxide and enhancement of its electrical and optical properties by attaching Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Khan, Sunny; Ali, Javid; Harsh; Husain, M.; Zulfequar, M.

    2016-07-01

    Graphene has attracted the attention of the scientists and researchers because of its peculiar properties. Because of various unique properties, graphene can be used in sensing device applications, solar cells and liquid crystal display devices etc. In this research paper, we present a chemical route towards bulk production of r-GO (reduced graphene oxide). We have employed a modified method to achieve better results which is often termed as modified Hummer's and Offeman method. It is modified in terms of filtration technique. We have also attached silver nanoparticles (Ag-NP) to as synthesised r-GO. After successful growth, silver nanoparticles have been attached to r-GO by suitable treatment with AgNO3 (aq.) N/50 solution. The as grown samples were characterised by FESEM, Raman Spectroscopy and EDS to make sure that r-GO and r-GO-Ag-NP have been successfully synthesised. The electrical and optical studies of the as grown samples were performed by dc conductivity measurements and UV visible spectroscopy. The conductivity was found to have increased with attachment of Ag-NP. The optical transmittance also improved to 90% as against 70% before Ag-NP attachment. The reduced graphene oxide attached with silver nanoparticles could find promising applications in synthesis of transparent electrode materials and optoelectronic devices.

  5. Fabrication of Ag nanowire and Al-doped ZnO hybrid transparent electrodes

    NASA Astrophysics Data System (ADS)

    You, Sslimsearom; Park, Yong Seo; Choi, Hyung Wook; Kim, Kyung Hwan

    2016-01-01

    Among the materials used as transparent electrodes, silver nanowires (AgNWs) have attracted attention because of their high transmittance and excellent conductivity. However, AgNWs have shortcomings, including their poor adhesion, oxidation by atmospheric oxygen, and unstable characteristics at high temperature. To overcome these shortcomings, multi-layer thin films with an aluminum-doped zinc oxide (AZO)/AgNW/AZO structure were fabricated using facing targets sputtering. The samples heated to 350 °C exhibited stable electrical characteristics. In addition, the adhesion to the substrate was improved compared with AgNWs layer. The AZO/AgNW/AZO thin films with multilayer structure overcame the shortcomings of AgNWs, and we propose their use as transparent electrodes with excellent properties for optoelectronic applications.

  6. Synthesis of nanoporous nickel thin films from various precursors

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Balk, T. John

    2014-09-01

    Multiple approaches to fabricate nanoporous nickel (np-Ni) thin films from NiCu, NiAl, NiFe and NiMg precursors are presented. Deposition of precursor films, dealloying and characterization of the nanoporous films by electron microscopy are discussed. All precursor alloys can yield np-Ni. However, dealloying of NiMg precursor films yields the most consistent, open-porosity structure with a ligament size of 7 nm, comparable to that of Raney nickel.

  7. Stroop interference and negative priming (NP) suppression in normal aging.

    PubMed

    Mayas, J; Fuentes, L J; Ballesteros, S

    2012-01-01

    Age-related differences in the reduction of Stroop interference were explored by comparing the performance of 18 younger (of mean age: 30.0±3.9 years) and 18 older healthy adults (of mean age: 75±7.2 years) in a color-word Stroop task. The aim of this study was to determine whether a decrease in the efficiency of inhibitory mechanisms associated with aging could account for age-related differences in the ability to suppress a pre-potent response. Participants performed a Stroop task to assess Stroop interference and NP suppression concurrently. Results showed a greater Stroop interference in older than in young adults. On the other hand, the NP effect was only reliable in the younger group, the older group not showing NP suppression. These findings suggest that the slowing hypothesis alone cannot explain this pattern of results and that the age-related differences must also involve an inhibitory breakdown during aging.

  8. AREVA NP Fuel Condition Index for Boiling Water Reactors

    SciTech Connect

    Pop, Mike G.; Bell, Merl; Lockamon, Brian

    2007-07-01

    Three factors are considered paramount in fuel performance: heat flux, crud layer, and oxide thickness. Both the crud layer and the oxide thickness may be affected by plant chemistry. During the last two years, AREVA NP has developed a Fuel Condition Index (FCI) that provides a method to assign a single numerical value connecting chemistry conditions to observed or expected fuel performance. The FCI also includes a heat-flux factor to allow evaluation of the condition of a BWR core. The chemistry parameters and acceptable operating ranges selected consider AREVA NP knowledge and Industry consensus. This paper describes the FCI developed by AREVA NP (patent pending) and the results of parameter sensitivity calculations that support the AREVA approach. This will provide the basis for subsequent application and benchmarking at an operating plant. (authors)

  9. Ag nanoparticle-deposited TiO2 nanotube arrays for electrodes of Dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kawamura, Go; Ohmi, Hayato; Tan, Wai Kian; Lockman, Zainovia; Muto, Hiroyuki; Matsuda, Atsunori

    2015-05-01

    Dye-sensitized solar cells composed of a photoanode of Ag nanoparticle (NP)-deposited TiO2 nanotube (TNT) arrays were fabricated. The TNT arrays were prepared by anodizing Ti films on fluorine-doped tin oxide (FTO)-coated glass substrates. Efficient charge transportation through the ordered nanostructure of TNT arrays should be carried out compared to conventional particulate TiO2 electrodes. However, it has been a big challenge to grow TNT arrays on FTO glass substrates with the lengths needed for sufficient light-harvesting (tens of micrometers). In this work, we deposited Ag nanoparticles (NPs) on the wall of TNT arrays to enhance light-harvesting property. Dye-sensitized solar cells with these Ag NP-deposited TNT arrays yielded a higher power conversion efficiency (2.03 %) than those without Ag NPs (1.39 %).

  10. Early stage fractal growth in thin films below the percolation limit

    NASA Astrophysics Data System (ADS)

    Batabyal, R.; Mahato, J. C.; Das, Debolina; Dev, B. N.

    2013-02-01

    We demonstrate the fractal growth of epitaxial Ag thin films on Si(111) surfaces using scanning tunneling microscopy (STM). The initial stage growth of Ag thin films provides islands of compact shape. These compact-shaped two-dimensional (2D) islands follow the Euclidian dimension 2. As the islands grow they become fractal in nature. The fractal (Hausdorff) dimension of the islands depends on the coverage of the Ag thin films. The mechanism responsible for this fractal nature of the Ag nanostructures varies from diffusion limited aggregation (DLA) to diffusion limited cluster aggregation (DLCA).

  11. Comparison of the Carba NP, Modified Carba NP, and Updated Rosco Neo-Rapid Carb Kit Tests for Carbapenemase Detection.

    PubMed

    AbdelGhani, Sameh; Thomson, Gina K; Snyder, James W; Thomson, Kenneth S

    2015-11-01

    The accurate detection of carbapenemase-producing organisms is a major challenge for clinical laboratories. The Carba NP test is highly accurate but inconvenient, as it requires frequent preparation of fresh imipenem solution. The current study was designed to compare the Carba NP test to two alternative tests for accuracy and convenience. These were a modified Carba NP test that utilized intravenous (i.v.) imipenem-cilastatin, which is less expensive than reference standard imipenem powder, and an updated version of the Rosco Neo-Rapid Carb kit, which does not require the preparation of imipenem solution and has a shelf life of 2 years. The comparison included 87 isolates that produced class A carbapenemases (including KPC-2, -3, -4, -5, -6, and -8, NMC-A, and SME type), 40 isolates that produced metallo-β-lactamases (including NDM-1, GIM-1, SPM-1, IMP-1, -2, -7, -8, -18, and -27, and VIM-1, -2, and -7), 11 isolates that produced OXA-48, and one isolate that produced OXA-181. Negative controls consisted of 50 isolates that produced extended-spectrum β-lactamases (ESBLs), AmpCs (including hyperproducers), K1, other limited-spectrum β-lactamases, and porin and efflux mutants. Each test exhibited 100% specificity and high sensitivity (Carba NP, 100%; Rosco, 99% using modified interpretation guidelines; and modified Carba NP, 96%). A modified approach to interpretation of the Rosco test was necessary to achieve the sensitivity of 99%. If the accuracy of the modified interpretation is confirmed, the Rosco test is an accurate and more convenient alternative to the Carba NP test. PMID:26311862

  12. AgRISTARS

    NASA Technical Reports Server (NTRS)

    1984-01-01

    An introduction to the overall AgRISTARS program, a general statement on progress, and separate summaries of the activities of each project, with emphasis on the technical highlights are presented. Organizational and management information on AgRISTARS is included in the appendices, as is a complete bibliography of publication and reports.

  13. AGS experiments: 1993 - 1994 - 1995

    SciTech Connect

    Depken, J.C.

    1996-04-01

    This report contains: FY 1995 AGS Schedule as Run; FY 1996-97 AGE Schedule (working copy); AGS Beams 1995; AGS Experimental Area FY 1993 Physics Program; AGS Experimental Area FY 1994 Physics Program; AGS Experimental Area FY 1995 Physics Program; AGS Experimental Area FY 1996 Physics Program (In progress); A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Listing of publications of AGS experiments begins here; and Listing of AGS experimenters begins here. This is the twelfth edition.

  14. Gamma beam industrial applications at ELI-NP

    NASA Astrophysics Data System (ADS)

    Suliman, Gabriel; Iancu, Violeta; Ur, Calin A.; Iovea, Mihai; Daito, Izuru; Ohgaki, Hideaki

    2016-09-01

    The Nuclear Physics oriented pillar of the pan-European Extreme Light Infrastructure (ELI-NP) will host an ultra-bright, energy tunable, and quasi-monochromatic gamma-ray beam system in the range of 0.2-19.5 MeV produced by laser Compton backscattering. This gamma beam satisfies the criteria for large-size product investigations with added capabilities like isotope detection through the use of nuclear resonance fluorescence (NRF) and is ideal for non-destructive testing applications. Two major applications of gamma beams are being envisaged at ELI-NP: industrial applications based on NRF and industrial radiography and tomography. Both applications exploit the unique characteristics of the gamma beam to deliver new opportunities for the industry. Here, we present the experimental setups proposed at ELI-NP and discuss their performance based on analytical calculations and GEANT4 numerical simulations. One of the main advantages of using the gamma beam at ELI-NP for applications based on NRF is the availability of an advanced detector array, which can enhance the advantages already provided by the high quality of the gamma beam.

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

    ERIC Educational Resources Information Center

    Hong, Sung-Ryong; Na, Won-Shik

    2011-01-01

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

  16. U, Np, Pu and Am Prompt Fission Neutron Spectra

    SciTech Connect

    Maslov, Vladimir M.

    2008-05-12

    Prompt fission neutron spectra (PFNS) components due to soft and hard pre-fission neutrons are revealed in PFNS data of {sup 232}Th(n,F), {sup 238}U(n,F), {sup 235}U(n,F) and {sup 239}Pu(n,F) reactions for E{sub n}{<=}20 MeV. Average energies of these PFNS are systematically shifted to higher values, so that Th fission fragments look least heated, while those of Pu--most heated. The average energy is correlated with the emissive fission chances contributions to the observed fission cross sections. The predicted contribution of (n,xnf) neutrons is most pronounced in case of {sup 232}Th(n,F) reaction. The approach, based on the consistent description of {sup 237}Np(n,F), {sup 237}Np(n,2n){sup 236s}Np and {sup 241}Am(n,F), {sup 241}Am(n,2n) is used to predict the PFNS of the {sup 237}Np(n,F) and {sup 241}Am(n,F) reactions.

  17. Current-perpendicular-to-the-plane giant magnetoresistance in spin-valves with AgSn alloy spacers

    SciTech Connect

    Read, J. C.; Nakatani, T. M.; Smith, Neil; Choi, Y.-S.; York, B. R.; Brinkman, E.; Childress, J. R.

    2015-07-28

    We investigate the use of AgSn alloys as the spacer layer in current-perpendicular-to-the-plane magnetoresistance devices. Alloying with Sn increases resistivity but results in a reasonably long (>10 nm) spin-diffusion length, so large magnetoresistance can be achieved with thin AgSn spacers. Compared to Ag thin films, AgSn forms smaller grain sizes, reduced roughness, and exhibits less interdiffusion upon annealing, resulting in decreased interlayer magnetic coupling in exchange biased spin-valves. AgSn also shows improved corrosion resistance compared to Ag, which is advantageous for nanofabrication, including magnetic recording head sensors. Combining a AgSn spacer with Co-based Heusler alloy ferromagnet in an exchange biased, polycrystalline trilayer thinner than 12 nm results in magnetoresistance values up to 15% at room temperature.

  18. Current-perpendicular-to-the-plane giant magnetoresistance in spin-valves with AgSn alloy spacers

    NASA Astrophysics Data System (ADS)

    Read, J. C.; Nakatani, T. M.; Smith, Neil; Choi, Y.-S.; York, B. R.; Brinkman, E.; Childress, J. R.

    2015-07-01

    We investigate the use of AgSn alloys as the spacer layer in current-perpendicular-to-the-plane magnetoresistance devices. Alloying with Sn increases resistivity but results in a reasonably long (>10 nm) spin-diffusion length, so large magnetoresistance can be achieved with thin AgSn spacers. Compared to Ag thin films, AgSn forms smaller grain sizes, reduced roughness, and exhibits less interdiffusion upon annealing, resulting in decreased interlayer magnetic coupling in exchange biased spin-valves. AgSn also shows improved corrosion resistance compared to Ag, which is advantageous for nanofabrication, including magnetic recording head sensors. Combining a AgSn spacer with Co-based Heusler alloy ferromagnet in an exchange biased, polycrystalline trilayer thinner than 12 nm results in magnetoresistance values up to 15% at room temperature.

  19. Silica Cladding of Ag Nanoparticles for High Stability and Surface-Enhanced Raman Spectroscopy Performance

    NASA Astrophysics Data System (ADS)

    Zhao, Miaomiao; Guo, Hao; Liu, Wenyao; Tang, Jun; Wang, Lei; Zhang, Binzhen; Xue, Chenyang; Liu, Jun; Zhang, Wendong

    2016-09-01

    For high-precision biochemical sensing, surface-enhanced Raman spectroscopy (SERS) has been demonstrated to be a highly sensitive spectroscopic analytical method and Ag is considered to be the best material for SERS performance. Due to the high surface activity of Ag nanoparticles, the high stability of Ag nanostructures, especially in moist environments, is one of the key issues that need to be solved. A method for silica (SiO2) cladding of Ag nanoparticles (NPs) is demonstrated here for high sensitivity and long-term stability when putted in aqueous solution. The chemically inert, transparent, hydrophilic, and bio-compatible SiO2 surface acts as the protection layer for the Ag nanoparticles, which can also enhance the Raman intensity to a certain extent. In our study, the Ag@SiO2 core-shell substrate can detect crystal violet solutions with molar concentrations down to 10-12 M. After 24 h of immersion, the reduction in Raman scattering intensity is about 85 % for sole Ag NP films, compared to 12 % for the Ag coated with a 10-nm SiO2 layer. This thickness was found to be optimum for Ag@SiO2 core-shell substrates with long-term stability and high SERS activity.

  20. Silica Cladding of Ag Nanoparticles for High Stability and Surface-Enhanced Raman Spectroscopy Performance.

    PubMed

    Zhao, Miaomiao; Guo, Hao; Liu, Wenyao; Tang, Jun; Wang, Lei; Zhang, Binzhen; Xue, Chenyang; Liu, Jun; Zhang, Wendong

    2016-12-01

    For high-precision biochemical sensing, surface-enhanced Raman spectroscopy (SERS) has been demonstrated to be a highly sensitive spectroscopic analytical method and Ag is considered to be the best material for SERS performance. Due to the high surface activity of Ag nanoparticles, the high stability of Ag nanostructures, especially in moist environments, is one of the key issues that need to be solved. A method for silica (SiO2) cladding of Ag nanoparticles (NPs) is demonstrated here for high sensitivity and long-term stability when putted in aqueous solution. The chemically inert, transparent, hydrophilic, and bio-compatible SiO2 surface acts as the protection layer for the Ag nanoparticles, which can also enhance the Raman intensity to a certain extent. In our study, the Ag@SiO2 core-shell substrate can detect crystal violet solutions with molar concentrations down to 10(-12) M. After 24 h of immersion, the reduction in Raman scattering intensity is about 85 % for sole Ag NP films, compared to 12 % for the Ag coated with a 10-nm SiO2 layer. This thickness was found to be optimum for Ag@SiO2 core-shell substrates with long-term stability and high SERS activity. PMID:27637895

  1. Kinetic trapping through coalescence and the formation of patterned Ag-Cu nanoparticles

    NASA Astrophysics Data System (ADS)

    Grammatikopoulos, Panagiotis; Kioseoglou, Joseph; Galea, Antony; Vernieres, Jerome; Benelmekki, Maria; Diaz, Rosa E.; Sowwan, Mukhles

    2016-05-01

    In recent years, due to its inherent flexibility, magnetron-sputtering has been widely used to synthesise bi-metallic nanoparticles (NPs) via subsequent inert-gas cooling and gas-phase condensation of the sputtered atomic vapour. Utilising two separate sputter targets allows for good control over composition. Simultaneously, it involves fast kinetics and non-equilibrium processes, which can trap the nascent NPs into metastable configurations. In this study, we observed such configurations in immiscible, bi-metallic Ag-Cu NPs by scanning transmission electron microscopy (S/TEM) and electron energy-loss spectroscopy (EELS), and noticed a marked difference in the shape of NPs belonging to Ag- and Cu-rich samples. We explained the formation of Janus or Ag@Cu core/shell metastable structures on the grounds of in-flight mixed NP coalescence. We utilised molecular dynamics (MD) and Monte Carlo (MC) computer simulations to demonstrate that such configurations cannot occur as a result of nanoalloy segregation. Instead, sintering at relatively low temperatures can give rise to metastable structures, which eventually can be stabilised by subsequent quenching. Furthermore, we compared the heteroepitaxial diffusivities along various surfaces of both Ag and Cu NPs, and emphasised the differences between the sintering mechanisms of Ag- and Cu-rich NP compositions: small Cu NPs deform as coherent objects on large Ag NPs, whereas small Ag NPs dissolve into large Cu NPs, with their atoms diffusing along specific directions. Taking advantage of this observation, we propose controlled NP coalescence as a method to engineer mixed NPs of a unique, patterned core@partial-shell structure, which we refer to as a ``glass-float'' (ukidama) structure.In recent years, due to its inherent flexibility, magnetron-sputtering has been widely used to synthesise bi-metallic nanoparticles (NPs) via subsequent inert-gas cooling and gas-phase condensation of the sputtered atomic vapour. Utilising two

  2. Hydrodynamic chromatography coupled to single-particle ICP-MS for the simultaneous characterization of AgNPs and determination of dissolved Ag in plasma and blood of burn patients.

    PubMed

    Roman, Marco; Rigo, Chiara; Castillo-Michel, Hiram; Munivrana, Ivan; Vindigni, Vincenzo; Mičetić, Ivan; Benetti, Federico; Manodori, Laura; Cairns, Warren R L

    2016-07-01

    Silver nanoparticles (AgNPs) are increasingly used in medical devices as innovative antibacterial agents, but no data are currently available on their chemical transformations and fate in vivo in the human body, particularly on their potential to reach the circulatory system. To study the processes involving AgNPs in human plasma and blood, we developed an analytical method based on hydrodynamic chromatography (HDC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) in single-particle detection mode. An innovative algorithm was implemented to deconvolute the signals of dissolved Ag and AgNPs and to extrapolate a multiparametric characterization of the particles in the same chromatogram. From a single injection, the method provides the concentration of dissolved Ag and the distribution of AgNPs in terms of hydrodynamic diameter, mass-derived diameter, number and mass concentration. This analytical approach is robust and suitable to study quantitatively the dynamics and kinetics of AgNPs in complex biological fluids, including processes such as agglomeration, dissolution and formation of protein coronas. The method was applied to study the transformations of AgNP standards and an AgNP-coated dressing in human plasma, supported by micro X-ray fluorescence (μXRF) and micro X-ray absorption near-edge spectroscopy (μXANES) speciation analysis and imaging, and to investigate, for the first time, the possible presence of AgNPs in the blood of three burn patients treated with the same dressing. Together with our previous studies, the results strongly support the hypothesis that the systemic mobilization of the metal after topical administration of AgNPs is driven by their dissolution in situ. Graphical Abstract Simplified scheme of the combined analytical approach adopted for studying the chemical dynamics of AgNPs in human plasma/blood.

  3. Nanoparticle size and morphology control using ultrafast laser induced forward transfer of Ni thin films

    SciTech Connect

    Murphy, Ryan D.; Abere, Michael J.; Schrider, Keegan J.; Yalisove, Steven M.; Torralva, Ben

    2013-08-26

    We have developed a nanoparticle (NP) printing technique using Ni thin film lift-off from glass substrates after ultrafast irradiation in air. Unique interactions of ultrafast laser pulses with thin films allow for control over NP faceting and size distributions. Control is achieved by changing the laser fluence, film thickness, and film-substrate distance. We demonstrate 20 nm Ni film removal from substrates and rapid NP printing, with size distributions centered at a 6 nm diameter. When the Ni film thickness is lowered to 10 nm, NPs are printed with distributions peaked at a 2 nm diameter.

  4. Electrical properties of thin-film structures formed by pulsed laser deposition of Au, Ag, Cu, Pd, Pt, W, Zr metals on n-6H-SiC crystal

    SciTech Connect

    Romanov, R. I.; Zuev, V. V.; Fominskii, V. Yu. Demin, M. V.; Grigoriev, V. V.

    2010-09-15

    Diode structures with ideality factors of 1.28-2.14 and potential barriers from 0.58 to 0.62 eV on the semiconductor side were formed by pulsed laser deposition of Au, Ag, Cu, Pd, Pt, W, and Zr metal films on n-6H-SiC crystal without epitaxial layer preparation. A high density of surface acceptor and donor states was formed at the metal-semiconductor interface during deposition of the laser-induced atomic flux, which violated the correlation between the potential barrier height and metal work function. The barrier heights determined from characteristic currents and capacitance measurements were in quite good agreement. For the used low-resistance semiconductor and contact elements, the sizes of majority carrier (electron) depletion regions were determined as 26-60 nm.

  5. Kinetic trapping through coalescence and the formation of patterned Ag-Cu nanoparticles.

    PubMed

    Grammatikopoulos, Panagiotis; Kioseoglou, Joseph; Galea, Antony; Vernieres, Jerome; Benelmekki, Maria; Diaz, Rosa E; Sowwan, Mukhles

    2016-05-14

    In recent years, due to its inherent flexibility, magnetron-sputtering has been widely used to synthesise bi-metallic nanoparticles (NPs) via subsequent inert-gas cooling and gas-phase condensation of the sputtered atomic vapour. Utilising two separate sputter targets allows for good control over composition. Simultaneously, it involves fast kinetics and non-equilibrium processes, which can trap the nascent NPs into metastable configurations. In this study, we observed such configurations in immiscible, bi-metallic Ag-Cu NPs by scanning transmission electron microscopy (S/TEM) and electron energy-loss spectroscopy (EELS), and noticed a marked difference in the shape of NPs belonging to Ag- and Cu-rich samples. We explained the formation of Janus or Ag@Cu core/shell metastable structures on the grounds of in-flight mixed NP coalescence. We utilised molecular dynamics (MD) and Monte Carlo (MC) computer simulations to demonstrate that such configurations cannot occur as a result of nanoalloy segregation. Instead, sintering at relatively low temperatures can give rise to metastable structures, which eventually can be stabilised by subsequent quenching. Furthermore, we compared the heteroepitaxial diffusivities along various surfaces of both Ag and Cu NPs, and emphasised the differences between the sintering mechanisms of Ag- and Cu-rich NP compositions: small Cu NPs deform as coherent objects on large Ag NPs, whereas small Ag NPs dissolve into large Cu NPs, with their atoms diffusing along specific directions. Taking advantage of this observation, we propose controlled NP coalescence as a method to engineer mixed NPs of a unique, patterned core@partial-shell structure, which we refer to as a "glass-float" (ukidama) structure. PMID:27119383

  6. It's Not Just the "Heavy NP": Relative Phrase Length Modulates the Production of Heavy-NP Shift

    ERIC Educational Resources Information Center

    Stallings, Lynne M.; MacDonald, Maryellen C.

    2011-01-01

    Heavy-NP shift is the tendency for speakers to place long direct object phrases at the end of a clause rather than next to the verb. Though some analyses have focused on length of the direct object phrase alone, results from two experiments demonstrate that the length of the direct object relative to that of other phrases, and not the length of…

  7. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

    ... their delicate appearance, thin, feathery clouds of ice crystals called cirrus may contribute to global warming. Some scientists ... July 9, 2002 - Thin, feathery clouds of ice crystals over the Caribbean Sea. project:  MISR ...

  8. Formation and properties of hyaluronan/nano Ag and hyaluronan-lecithin/nano Ag films.

    PubMed

    Khachatryan, Gohar; Khachatryan, Karen; Grzyb, Jacek; Fiedorowicz, Maciej

    2016-10-20

    A facile and environmentally friendly method of the preparation of silver nanoparticles embedded in hyaluronan (Hyal/Ag) and hyaluronan-lecithin (Hyal-L/Ag) matrix was developed. Thin, elastic foils were prepared from gels by an in situ synthesis of Ag in an aqueous solution of sodium hyaluronate (Hyal), using aq. d-(+)-xylose solution as a reducing agent. The gels were applied to a clean, smooth, defatted Teflon surface and left for drying in the air. The dry foils were stored in a closed container. UV-vis spectroscopy, transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectra confirmed formation of about 10nm ball-shaped Ag nanoparticles situated within the polysaccharide template. Thermal properties of the composites were characterized involving differential scanning calorimetry (DSC) and thermogravimetric (TGA) analyses, whereas molecular weights of polysaccharide chains of the matrix were estimated with the size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI). An increase in the molecular weight of the hyaluronate after generation of Ag nanoparticles was observed. The foils showed specific properties. The study confirmed that silver nanoparticles can be successfully prepared with environmentally friendly method, using hyaluronan as a stabilizing template. Hyaluronan and hyaluronan-lecithin matrices provide nanocrystals uniform in size and shape. The composites demonstrated a bacteriostatic activity. PMID:27474588

  9. Effect of Ag doping and annealing on thermoelectric properties of PbTe

    SciTech Connect

    Bala, Manju Tripathi, T. S.; Avasthi, D. K.; Asokan, K.; Gupta, Srashti

    2015-06-24

    The present study reveals that annealing Ag doped PbTe thin films enhance thermoelectric properties. Phase formation was identified by using X-ray diffraction measurement. Annealing increases the crystallinity of both undoped and Ag doped PbTe. Electrical resistivity and thermoelectric power measurements are done using four probe and bridge method respectively. The increase in thermoelectric power of Ag doped PbTe is 29 % in comparison to undoped PbTe and it further increases to 34 % after annealing at 250{sup o} C for 1 hour whereas thermoelectric power increases by 14 % on annealing undoped PbTe thin films at same temperature.

  10. Co-doping effects of Gd and Ag on YBCO films derived by metalorganic deposition

    NASA Astrophysics Data System (ADS)

    Sun, Meijuan; Liu, Zhiyong; Bai, Chuanyi; Guo, Yanqun; Lu, Yuming; Fan, Feng; Cai, Chuanbing

    2015-12-01

    Y1-xGdxBa2Cu3O7-δ-Ag (x = 0, 0.25, 0.5, 0.75, 1) thin films were prepared on oxide buffered Hastelloy substrates by low fluorine metalorganic depostion (MOD) process. The effects of co-doping of Ag and Gd on the microstructures and superconducting properties of YBCO thin films are investigated with respect to improvement on texture and superconducting performance in case of optimized doping content. It is found that optimum addition of Ag and Gd may lead to better c-axis orientation, superior surface microstructure and finally give rise to much improvement of superconducting performance.

  11. Luminescent and structural properties of ZnO-Ag films

    SciTech Connect

    Khomchenko, V. S. Kushnirenko, V. I. Papusha, V. P.; Savin, A. K.; Lytvyn, O. S.

    2010-05-15

    ZnO-Ag thin films were prepared by a two-stage method on glass and sapphire substrates. Ag doping was carried out by a method of close space sublimation at atmospheric pressure. The film thickness is varied from 0.6 to 7 {mu}m. The structural and radiative properties were explored by X-ray diffraction technique, atomic force microscopy, photoluminescence and cathodoluminescence spectroscopy. The influence of the fabricating conditions on the properties of ZnO-Ag films is studied. It is found that the Ag doping modifies the crystalline structure of the films and promotes the oriented growth of monocrystalline blocks with the size of 500-2000 nm in the [0002] direction. Improvement of the crystalline quality correlates with the change of the radiative characteristics of the films. The origin of emission centers is discussed.

  12. Radial direct bandgap p-i-n GaNP microwire solar cells with enhanced short circuit current

    NASA Astrophysics Data System (ADS)

    Sukrittanon, Supanee; Liu, Ren; Breeden, Michael C.; Pan, Janet L.; Jungjohann, K. L.; Tu, Charles W.; Dayeh, Shadi A.

    2016-08-01

    We report the demonstration of dilute nitride heterostructure core/shell microwire solar cells utilizing the combination of top-down reactive-ion etching to create the cores (GaP) and molecular beam epitaxy to create the shells (GaNP). Systematic studies of cell performance over a series of microwire lengths, array periods, and microwire sidewall morphologies examined by transmission electron microscopy were conducted to shed light on performance-limiting factors and to optimize the cell efficiency. We show by microscopy and correlated external quantum efficiency characterization that the open circuit voltage is degraded primarily due to the presence of defects at the GaP/GaNP interface and in the GaNP shells, and is not limited by surface recombination. Compared to thin film solar cells in the same growth run, the microwire solar cells exhibit greater short circuit current but poorer open circuit voltage due to greater light absorption and number of defects in the microwire structure, respectively. The comprehensive understanding presented in this work suggests that performance benefits of dilute nitride microwire solar cells can be achieved by further tuning of the epitaxial quality of the underlying materials.

  13. Method for separating actinides. [Patent application; stripping of Np from organic extractant

    DOEpatents

    Friedman, H.A.; Toth, L.M.

    1980-11-10

    An organic solution used for processing spent nuclear reactor fuels is contacted with an aqueous nitric acid solution to strip Np(VI), U(VI), and Pu(IV) from the organic solution into the acid solution. The acid solution is exposed to ultraviolet light, which reduces Np(VI) to Np(V) without reducing U(VI) and Pu(IV). Since the solubility of Np(V) in the organic solution is much lower than that of Np(VI), U(VI), and Pu(IV), a major part of the Np is stripped from the organic solution while leaving most of the U and Pu therein.

  14. Covariant spectator theory of np scattering: Deuteron quadrupole moment

    SciTech Connect

    Gross, Franz

    2015-01-26

    The deuteron quadrupole moment is calculated using two CST model wave functions obtained from the 2007 high precision fits to np scattering data. Included in the calculation are a new class of isoscalar np interaction currents automatically generated by the nuclear force model used in these fits. The prediction for model WJC-1, with larger relativistic P-state components, is 2.5% smaller that the experiential result, in common with the inability of models prior to 2014 to predict this important quantity. However, model WJC-2, with very small P-state components, gives agreement to better than 1%, similar to the results obtained recently from XEFT predictions to order N3LO.

  15. Covariant spectator theory of np scattering: Deuteron quadrupole moment

    DOE PAGES

    Gross, Franz

    2015-01-26

    The deuteron quadrupole moment is calculated using two CST model wave functions obtained from the 2007 high precision fits to np scattering data. Included in the calculation are a new class of isoscalar np interaction currents automatically generated by the nuclear force model used in these fits. The prediction for model WJC-1, with larger relativistic P-state components, is 2.5% smaller that the experiential result, in common with the inability of models prior to 2014 to predict this important quantity. However, model WJC-2, with very small P-state components, gives agreement to better than 1%, similar to the results obtained recently frommore » XEFT predictions to order N3LO.« less

  16. ICANP2: Isoenergetic cluster algorithm for NP-complete Problems

    NASA Astrophysics Data System (ADS)

    Zhu, Zheng; Fang, Chao; Katzgraber, Helmut G.

    NP-complete optimization problems with Boolean variables are of fundamental importance in computer science, mathematics and physics. Most notably, the minimization of general spin-glass-like Hamiltonians remains a difficult numerical task. There has been a great interest in designing efficient heuristics to solve these computationally difficult problems. Inspired by the rejection-free isoenergetic cluster algorithm developed for Ising spin glasses, we present a generalized cluster update that can be applied to different NP-complete optimization problems with Boolean variables. The cluster updates allow for a wide-spread sampling of phase space, thus speeding up optimization. By carefully tuning the pseudo-temperature (needed to randomize the configurations) of the problem, we show that the method can efficiently tackle problems on topologies with a large site-percolation threshold. We illustrate the ICANP2 heuristic on paradigmatic optimization problems, such as the satisfiability problem and the vertex cover problem.

  17. Neutron average cross sections of {sup 237}Np

    SciTech Connect

    Noguere, G.

    2010-04-15

    This work reports {sup 237}Np neutron resonance parameters obtained from the simultaneous analysis of time-of-flight data measured at the GELINA, ORELA, KURRI, and LANSCE facilities. A statistical analysis of these resonances relying on average R-matrix and optical model calculations was used to establish consistent l-dependent average resonance parameters involved in the description of the unresolved resonance range of the {sup 237}Np neutron cross sections. For neutron orbital angular momentum l=0, we obtained an average radiation width =39.3+-1.0 meV, a neutron strength function 10{sup 4}S{sub 0}=1.02+-0.14, a mean level spacing D{sub 0}=0.60+-0.03 eV, and a potential scattering length R{sup '}=9.8+-0.1 fm.

  18. Lab Scale Production of NpO2

    SciTech Connect

    Duffey, J

    2003-08-29

    The Savannah River Site (SRS) plans to disposition its legacy H-Canyon neptunium to Oak Ridge National Laboratory after converting it to oxide in HB-Line. Neptunium oxide, (NpO{sub 2}) was produced at the Savannah River Technology Center using the anticipated HB-Line flowsheet conditions. The oxide was produced from a neptunium nitrate solution via anion exchange, oxalate precipitation, and calcination at either 600 C or 650 C. The 98 grams of NpO{sub 2} produced in the laboratory should be representative of material produced in HB-Line and is to be used for gas generation testing to support radioactive material transportation safety analysis as part of the neptunium stabilization and disposition program at SRS. Results of each step of the oxide production will be presented.

  19. Impedance studies of the cell Ag/AgI/Ag beta alumina/AgI/Ag. Technical report No. 15, August 1987-August 1988

    SciTech Connect

    Breiter, M.W.; Drstak, H.; Maly-Schreiber, M.

    1988-07-01

    The construction of the cell Ag/AgI/Ag beta alumina/AgI/Ag is described. The impedance of this cell was measured between .001 and 10000 Hz at temperatures between 20 and 550 C. At temperatures below 100 C the cell impedance is determined to a large extent by the bulk resistance of the AgI layer and to a smaller extent by the impedance of the interface Ag/Agi. At temperatures between 160 and 350 C the impedance is controlled by the bulk resistance of the Ag beta alumina and an impedance due to contact problems between Ag and AgI. The bulk resistance of the beta' alumina becomes predominant between 350 and 550 C. A hindrance due to the transfer of silver ions from AgI to Ag beta' alumina was not observable in the whole temperature range.

  20. Direct nano-scale patterning of Ag films using hard X-ray induced oxidation.

    PubMed

    Kim, Jae Myung; Lee, Su Yong; Kang, Hyon Chol; Noh, Do Young

    2015-01-01

    The morphological change of silver nano-particles (AgNPs) exposed to an intense synchrotron X-ray beam was investigated for the purpose of direct nano-scale patterning of metal thin films. AgNPs irradiated by hard X-rays in oxygen ambient were oxidized and migrated out of the illuminated region. The observed X-ray induced oxidation was utilized to fabricate nano-scale metal line patterns using sectioned WSi2/Si multilayers as masks. Lines with a width as small as 21 nm were successfully fabricated on Ag films on silicon nitride. Au/Ag nano-lines were also fabricated using the proposed method.

  1. Rapidec Carba NP Test for Rapid Detection of Carbapenemase Producers

    PubMed Central

    Poirel, Laurent

    2015-01-01

    Performances of the Rapidec Carba NP test (bioMérieux) were evaluated for detection of all types of carbapenemases in Enterobacteriaceae, Acinetobacter baumannii, and Pseudomonas aeruginosa. In less than 2 h after sample preparation, it showed a sensitivity and specificity of 96%. This ready-to-use test is well adapted to the daily need for detection of carbapenemase producers in any laboratory worldwide. PMID:26085619

  2. In-situ spectro-microscopy on organic films: Mn-Phthalocyanine on Ag(100)

    SciTech Connect

    Al-Mahboob A.; Vescovo, E.; Sadowski, J.T.

    2013-08-18

    Metal phthalocyanines are attracting significant attention, owing to their potential for applications in chemical sensors, solar cells and organic magnets. As the electronic properties of molecular films are determined by their crystallinity and molecular packing, the optimization of film quality is important for improving the performance of organic devices. Here, we present the results of in situ low-energy electron microscopy / photoemission electron microscopy (LEEM/PEEM) studies of incorporation-limited growth [1] of manganese-phthalocyanine (MnPc) on Ag(100) surfaces. MnPc thin films were grown on both, bulk Ag(100) surface and thin Ag(100)/Fe(100) films, where substrate spin-polarized electronic states can be modified through tuning the thickness of the Ag film [2]. We also discuss the electronic structure and magnetic ordering in MnPc thin films, investigated by angle- and spin-resolved photoemission spectroscopy.

  3. Kondo bahavior in antiferromagnetic NpPdSn

    NASA Astrophysics Data System (ADS)

    Shrestha, K.; Prokes, K.; Griveau, J.-C.; Jardin, R.; Colineau, E.; Caciuffo, R.; Eloirdi, R.; Gofryk, K.

    Actinide-based intermetallics show a large variety of exotic physical phenomena mainly coming from 5f hybridization with both on-site and neighboring ligand states. Depending on the strength of these process unusual behaviors such as long-range magnetic order, Kondo effect, heavy-fermion ground state, valence fluctuations, and/or superconductivity have been observed. Here we report results of our extensive studies on NpPdSn. The compound crystalizes in hexagonal ZrNiAl-type of crystal structure and is studied by means of x-ray and neutron diffraction, magnetization, heat capacity, electrical resistivity, and thermoelectric power measurements, performed over a wide range of temperatures and applied magnetic fields. All the results revealed Kondo lattice behavior and antiferromagnetic ordering below 19 K. NpPdSn can be classified as a moderately enhanced heavy-fermion system, one of very few known amidst Np-based intermetallics. Work at Idaho National Laboratory was supported by the Department of Energy, Office of Basic Energy Sciences, Materials Sciences, and Engineering Division.

  4. Global Optimal Trajectory in Chaos and NP-Hardness

    NASA Astrophysics Data System (ADS)

    Latorre, Vittorio; Gao, David Yang

    This paper presents an unconventional theory and method for solving general nonlinear dynamical systems. Instead of the direct iterative methods, the discretized nonlinear system is first formulated as a global optimization problem via the least squares method. A newly developed canonical duality theory shows that this nonconvex minimization problem can be solved deterministically in polynomial time if a global optimality condition is satisfied. The so-called pseudo-chaos produced by linear iterative methods are mainly due to the intrinsic numerical error accumulations. Otherwise, the global optimization problem could be NP-hard and the nonlinear system can be really chaotic. A conjecture is proposed, which reveals the connection between chaos in nonlinear dynamics and NP-hardness in computer science. The methodology and the conjecture are verified by applications to the well-known logistic equation, a forced memristive circuit and the Lorenz system. Computational results show that the canonical duality theory can be used to identify chaotic systems and to obtain realistic global optimal solutions in nonlinear dynamical systems. The method and results presented in this paper should bring some new insights into nonlinear dynamical systems and NP-hardness in computational complexity theory.

  5. Behavior of Np(VII, VI, V) in Silicate Solutions

    SciTech Connect

    Shilov, V P.; Fedoseev, A M.; Yusov, A B.; Delegard, Calvin H.

    2004-11-30

    Spectrophotometric methods were used to investigate the properties of neptunium(VII), (VI), and (V) in silicate solution. The transition of cationic neptunium(VII) to anionic species in non-complexing environments proceeds in the range of ?? 5.5 to 7.5. In the presence of carbonate, this transition occurs at ?? 10.0 to 11.5 and in silicate solutions at ?? 10.5-12.0. These findings show that cationic neptunium(VII) forms complexes with both carbonate and silicate and that the silicate complex is stronger than that of the carbonate. The competition of complex formation reactions for neptunium(VI) with carbonate and silicate and on the known complex stability constant of NpO2(CO3)34- allowed the NpO2SiO3 complex stability constant, log ? = 16.5, to be estimated. Determination of the formation constant of Np(V) complexes with SiO32- was not possible using similar methods.

  6. P/NP, and the quantum field computer.

    PubMed

    Freedman, M H

    1998-01-01

    The central problem in computer science is the conjecture that two complexity classes, P (polynomial time) and NP (nondeterministic polynomial time-roughly those decision problems for which a proposed solution can be checked in polynomial time), are distinct in the standard Turing model of computation: P not equal NP. As a generality, we propose that each physical theory supports computational models whose power is limited by the physical theory. It is well known that classical physics supports a multitude of implementation of the Turing machine. Non-Abelian topological quantum field theories exhibit the mathematical features necessary to support a model capable of solving all #P problems, a computationally intractable class, in polynomial time. Specifically, Witten [Witten, E. (1989) Commun. Math. Phys. 121, 351-391] has identified expectation values in a certain SU(2)-field theory with values of the Jones polynomial [Jones, V. (1985) Bull. Am. Math. Soc. 12, 103-111] that are #P-hard [Jaeger, F., Vertigen, D. & Welsh, D. (1990) Math. Proc. Comb. Philos. Soc. 108, 35-53]. This suggests that some physical system whose effective Lagrangian contains a non-Abelian topological term might be manipulated to serve as an analog computer capable of solving NP or even #P-hard problems in polynomial time. Defining such a system and addressing the accuracy issues inherent in preparation and measurement is a major unsolved problem.

  7. P/NP, and the quantum field computer

    PubMed Central

    Freedman, Michael H.

    1998-01-01

    The central problem in computer science is the conjecture that two complexity classes, P (polynomial time) and NP (nondeterministic polynomial time—roughly those decision problems for which a proposed solution can be checked in polynomial time), are distinct in the standard Turing model of computation: P ≠ NP. As a generality, we propose that each physical theory supports computational models whose power is limited by the physical theory. It is well known that classical physics supports a multitude of implementation of the Turing machine. Non-Abelian topological quantum field theories exhibit the mathematical features necessary to support a model capable of solving all ⧣P problems, a computationally intractable class, in polynomial time. Specifically, Witten [Witten, E. (1989) Commun. Math. Phys. 121, 351–391] has identified expectation values in a certain SU(2)-field theory with values of the Jones polynomial [Jones, V. (1985) Bull. Am. Math. Soc. 12, 103–111] that are ⧣P-hard [Jaeger, F., Vertigen, D. & Welsh, D. (1990) Math. Proc. Comb. Philos. Soc. 108, 35–53]. This suggests that some physical system whose effective Lagrangian contains a non-Abelian topological term might be manipulated to serve as an analog computer capable of solving NP or even ⧣P-hard problems in polynomial time. Defining such a system and addressing the accuracy issues inherent in preparation and measurement is a major unsolved problem. PMID:9419335

  8. Phase relations in neptunium, americium and the binary alloy systems Np-Am and Np-Ln (Ln = La, Nd, Lu)

    NASA Astrophysics Data System (ADS)

    Gibson, John K.; Haire, Richard G.

    1992-10-01

    High-temperature differential thermal analysis has been used to characterize the phase relations in neptunium, americium and the binary alloy systems, Np-Am, Np-La, Np-Nd, Np-Lu, Sm-Ce and Ce-Gd. The temperatures previously reported for the two solid-solid transformations and the fusion of Np, and for the β(fcc) → γ(bcc?) and the fusion transitions of Am were confirmed. A small endothermic event ( ~ 0.4 kJ mol -1) evident at 758°C for americium was assigned to its dhcp → fcc transition; this temperature is ~ 100°C higher than previously derived from dilatometry. Although the Np-Am DTA studies were limited in the range of alloy compositions which could be investigated, the results were useful in deciphering the nature of the phase diagram. Measurements on a sample of aggregate composition Np 0.54-Am 0.46 suggested some degree of mutual solubility, although two (terminal) solid phases, one Np-rich and one Am-rich, were found to coexist. The supporting studies of Np-Ln and Ln-Ln' (Ln and Ln' = selected lanthanides) alloy systems established the efficacy of the DTA technique and augmented the results for the Np-Am system.

  9. NP1EC Degradation Pathways Under Oxic and Microxic Conditions

    SciTech Connect

    Montgomery-Brown, John; Li, Yongmei; Ding, Wang-Hsien; Mong, Gary M.; Campbell, James A.; Reinhard, Martin

    2008-03-22

    The degradation pathway of nonylphenol ethoxyacetic acid (NP1EC) and the conditions favoring CAP1EC formation were studied in aerobic microcosms constructed with soil from the Mesa soil aquifer treatment (SAT) facility (Arizona, USA) and pristine sediments from Coyote Creek (California, USA). In the Mesa microcosms, para-NP1EC was transformed to para-NP, before being rapidly transformed to nonyl alcohols via ipso-hydroxylation. While the formation of NP from APEMs has been observed by several researchers under anaerobic conditions, this is the first time the transient formation of NP from APEMs has been observed under aerobic conditions. Unlike the Mesa microcosms, large quantities of CAP1ECs were observed in the Coyote Creek microcosms. Initially, CA8P1ECs were the dominant metabolites, but as biodegradation continued, CA6P1ECs became the dominant metabolites. Compared to the CA8P1ECs, the number of CA6P1ECs peaks observed was small (<6) even though their concentrations were high. This suggests that several CA8P1ECs are degraded to only a few CA6P1EC isomers (i.e., the degradation pathway converges) or that some CA6P1EC metabolites are significantly more recalcitrant than others. The different biodegradation pathways observed in the Mesa and Coyote Creek microcosms result from the limited availability of dissolved oxygen in the Coyote Creek microcosms. In both sets of microcosms, the ortho isomers were transformed more slowly than the para isomers and in the Coyote Creek microcosms several ortho-CAP1ECs were observed. In addition, several unknown metabolites were observed in the Coyote Creek microcosms that were not seen in the abiotic or Mesa microcosms; these metabolites appear to be CAP1EC metabolites, have a -CH2-C6H4- fragment, and contain one carboxylic acid. Nitro-nonylphenol was observed in the Mesa microcosms, however, further experimentation illustrated that it was the product of an abiotic reaction between nitrite and nonylphenol under acidic conditions.

  10. NMR Studies of the Dynamics of High-Spin Nitrophorins: Comparative Studies of NP4 and NP2 at Close to Physiological pH

    PubMed Central

    2015-01-01

    The β-barrel nitrophorin (NP) heme proteins are found in the saliva of the blood-sucking insect Rhodnius prolixus, which synthesizes and stores nitric oxide (NO) in the salivary glands. NO is bound to iron of the NPs and is released by dilution and an increase in pH when the insect spits its saliva into the tissues of a victim, to aid in obtaining a blood meal. In the adult insect, there are four nitrophorins, NP1–NP4, which have sequence similarities in two pairs, NP1 and NP4 (90% identical) and NP2 and NP3 (80% identical). The available crystal structures of NP4 have been used to propose that pH-dependent changes in the conformation of two loops between adjacent β-strands at the front opening of the protein, the A–B and G–H loops, determine the rate of NO release. At pH 7.3, NP4 releases NO 17 times faster than NP2 does. In this work, the aqua complexes of NP4 and NP2 have been investigated by nuclear magnetic resonance (NMR) relaxation measurements to probe the pico- to nanosecond and micro- to millisecond time scale motions at two pH values, 6.5 and 7.3. It is found that NP4-OH2 is fairly rigid and only residues in the loop regions show dynamics at pH 6.5; at pH 7.3, much more dynamics of the loops and most of the β-strands are observed while the α-helices remain fairly rigid. In comparison, NP2-OH2 shows much less dynamics, albeit somewhat more than that of the previously reported NP2-NO complex [Muthu, D., Berry, R. E., Zhang, H., and Walker, F. A. (2013) Biochemistry 52, 7910–7925]. The reasons for this major difference between NP4 and NP2 are discussed. PMID:25486224

  11. Np and Pu Sorption to Manganese Oxide Minerals

    SciTech Connect

    Zhao, P; Johnson, M R; Roberts, S K; Zavarin, M

    2005-08-30

    Manganese oxide minerals are a significant component of the fracture lining mineralogy at Yucca Mountain (Carlos et al., 1993) and within the tuff-confining unit at Yucca Flat (Prothro, 1998), Pahute Mesa (Drellack et al., 1997), and other locations at the Nevada Test Site (NTS). Radionuclide sorption to manganese oxide minerals was not included in recent Lawrence Livermore National Laboratory (LLNL) hydrologic source term (HST) models which attempt to predict the migration behavior of radionuclides away from underground nuclear tests. However, experiments performed for the Yucca Mountain Program suggest that these minerals may control much of the retardation of certain radionuclides, particularly Np and Pu (Triay et al., 1991; Duff et al., 1999). As a result, recent HST model results may significantly overpredict radionuclide transport away from underground nuclear tests. The sorption model used in HST calculations performed at LLNL includes sorption to iron oxide, calcite, zeolite, smectite, and mica minerals (Zavarin and Bruton 2004a; 2004b). For the majority of radiologic source term (RST) radionuclides, we believe that this accounts for the dominant sorption processes controlling transport. However, for the case of Np, sorption is rather weak to all but the iron and manganese oxides (Figure 1). Thus, we can expect to significantly reduce predicted Np transport by accounting for Np sorption to manganese oxides. Similarly, Pu has been shown to be predominantly associated with manganese oxides in Yucca Mountain fractured tuffs (Duff et al., 1999). Recent results on colloid-facilitated Pu transport (Kersting and Reimus, 2003) also suggest that manganese oxide coatings on fracture surfaces may compete with colloids for Pu, thus reducing the effects of colloid-facilitated Pu transport (Figure 1b). The available data suggest that it is important to incorporate Np and Pu sorption to manganese oxides in reactive transport models. However, few data are available for

  12. Microstructure and tribological properties of NbN-Ag composite films by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ju, Hongbo; Xu, Junhua

    2015-11-01

    Recently, the chameleon thin films were developed with the purpose of adjusting their chemistry at self-mating interfaces in response to environmental changes at a wide temperature range. However, very few studies have focused on what state the lubricious noble metal exists in the films and the tribological properties at room temperature (RT). Composite NbN-Ag films with various Ag content (Ag/(Nb + Ag)) were deposited using reactive magnetron sputtering to investigate the crystal structure, mechanical and tribological properties. A combination of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) analyses showed that face-centered cubic (fcc) NbN, hexagonal close-packed (hcp) NbN and fcc silver coexisted in NbN-Ag films. The incorporation of soft Ag into NbN matrix led to the hardness decrease from 29.6 GPa at 0 at.% Ag to 11.3 GPa at 19.9 at.% Ag. Tribological properties of NbN-Ag films performed using dry pin-on-disc wear tests against Al2O3 depended on Ag content to a large extent. The average friction coefficient and wear rate of NbN-Ag films decreased as Ag content increased from 4.0 to 9.2 at.%. With a further increase of Ag content, the average friction coefficient further decreased, while the wear rate increased gradually. The optimal Ag content was found to be 9.2-13.5 at.%, which showed low average friction coefficient values of 0.46-0.40 and wear rate values of 1.1 × 10-8 to 1.7 × 10-8 mm3/(mm N). 3D Profiler and Raman spectroscopy measurements revealed that the lubricant tribo-film AgNbO3 detected on the surface of the wear tracks could lead to the friction coefficient curve stay constant and decrease the average friction coefficients. The decrease of wear rate was mainly attributed to the lubricant tribo-film AgNbO3 as Ag content increased from 4.0 to 9.2 at.%; with a further increase in Ag content, the wear rate increased with increasing Ag content in NbN-Ag films because a

  13. A HSV-1 variant (1720) generates four equimolar isomers despite a 9200-bp deletion from TRL and sequences between 9200 np and 97,000 np in inverted orientation being covalently bound to sequences 94,000-126,372 np.

    PubMed

    Harland, J; Brown, S M

    1992-08-01

    The genome structure of a spontaneously generated HSV-1 strain 17 variant, 1720, has been determined by restriction endonuclease and Southern blot analysis. The short segment of 1720 is unaltered compared to the parental strain 17 genome, whereas the long segment is extensively rearranged. Almost all of TRL (approximately 9.2 kb) has been deleted and consequently IRL is converted into unique sequence. Sequences from approximately 9200 nucleotide position (np) to 97,000 np are present in inverted orientation, covalently bound to sequences in the prototype orientation from approximately 94,000 np to the L/S junction at 126,372 np. Thus, sequences from 94,000 np to 97,000 np are now diploid, with one copy in the normal orientation and location, and the other at the long terminus as an inverted repeat; no inversion of the intervening unique sequences occurs about this novel inverted repeat. In contrast, normal inversions of the long and short segments occur to give four equimolar genomic isomers, indicating that the novel long terminus has gained an "a" sequence. The duplication of sequences between 94,000 np and 97,000 np results in a genome containing two copies of UL43 and one complete and one partial copy each of genes UL42 and UL44 encoding the 65 kD DNA-binding protein and glycoprotein C, respectively. The variant has been shown to grow normally in vitro following high multiplicity infection.

  14. Simulation of photofission experiments at the ELI-NP facility

    NASA Astrophysics Data System (ADS)

    Constantin, P.; Balabanski, D. L.; Cuong, P. V.

    2016-04-01

    An extensive experimental program for the study of photofission will take place at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility, where different actinide targets will be exposed to a brilliant gamma beam to produce fission fragments. We report on the implementation within the Geant4 simulation toolkit of the photofission process, of related background processes, and of extended ionic charge parameterization. These developments are used to evaluate the production rates of photofission fragments and their release efficiency from the actinide targets.

  15. Improvement of polypyrrole nanowire devices by plasmonic space charge generation: high photocurrent and wide spectral response by Ag nanoparticle decoration

    NASA Astrophysics Data System (ADS)

    Lee, S.-H.; Bae, J.; Lee, S. W.; Jang, J.-W.

    2015-10-01

    In this study, improvement of the opto-electronic properties of non-single crystallized nanowire devices with space charges generated by localized surface plasmon resonance (LSPR) is demonstrated. The photocurrent and spectral response of single polypyrrole (PPy) nanowire (NW) devices are increased by electrostatically attached Ag nanoparticles (Ag NPs). To take advantage of plasmon-exciton coupling in the photocurrent of the device, 80 nm of Ag NPs (454 nm = λmax) were chosen for matching the maximum absorption with PPy NWs (442 nm = λmax). The photocurrent density is remarkably improved, up to 25.3 times (2530%), by the Ag NP decoration onto the PPy NW (PPyAgNPs NW) under blue light (λ = 425-475 nm) illumination. In addition, the PPyAgNPs NW shows a photocurrent decay time twice that of PPy NW, as well as an improved spectral response of the photocurrent. The improved photocurrent efficiency, decay time, and spectral response resulted from the space charges generated by the LSPR of Ag NPs. Furthermore, the increasing exponent (m) of the photocurrent (JPC ~ Vm) and finite-differential time domain (FDTD) simulation straightforwardly indicate relatively large plasmonic space charge generation under blue light illumination. These results prove that the performance of non-single crystallized polymer nanowire devices can also be improved by plasmonic enhancement.In this study, improvement of the opto-electronic properties of non-single crystallized nanowire devices with space charges generated by localized surface plasmon resonance (LSPR) is demonstrated. The photocurrent and spectral response of single polypyrrole (PPy) nanowire (NW) devices are increased by electrostatically attached Ag nanoparticles (Ag NPs). To take advantage of plasmon-exciton coupling in the photocurrent of the device, 80 nm of Ag NPs (454 nm = λmax) were chosen for matching the maximum absorption with PPy NWs (442 nm = λmax). The photocurrent density is remarkably improved, up to 25.3 times

  16. The effect of TiO{sub 2} and Ag nanoparticles on reproduction and development of Drosophila melanogaster and CD-1 mice

    SciTech Connect

    Philbrook, Nicola A.; Winn, Louise M.; Afrooz, A.R.M. Nabiul; Saleh, Navid B.; Walker, Virginia K.

    2011-12-15

    In the last two decades, nanoparticles (NPs) have found applications in a wide variety of consumer goods. Titanium dioxide (TiO{sub 2}) and silver (Ag) NPs are both found in cosmetics and foods, but their increasing use is of concern due to their ability to be taken up by biological systems. While there are some reports of TiO{sub 2} and Ag NPs affecting complex organisms, their effects on reproduction and development have been largely understudied. Here, the effects of orally administered TiO{sub 2} or Ag NPs on reproduction and development in two different model organisms were investigated. TiO{sub 2} NPs reduced the developmental success of CD-1 mice after a single oral dose of 100 or 1000 mg/kg to dams, resulting in a statistically significant increase in fetal deformities and mortality. Similarly, TiO{sub 2} NP addition to food led to a significant progeny loss in the fruit fly, Drosophila, as shown by a decline in female fecundity. Ag NP administration resulted in an increase in the mortality of fetal mice. Similarly in Drosophila, Ag NP feeding led to a significant decrease in developmental success, but unlike TiO{sub 2} NP treatment, there was no decline in fecundity. The distinct response associated with each type of NP likely reflects differences in NP administration as well as the biology of the particular model. Taken together, however, this study warns that these common NPs could be detrimental to the reproductive and developmental health of both invertebrates and vertebrates.

  17. The ELI-NP facility for nuclear physics

    NASA Astrophysics Data System (ADS)

    Ur, C. A.; Balabanski, D.; Cata-Danil, G.; Gales, S.; Morjan, I.; Tesileanu, O.; Ursescu, D.; Ursu, I.; Zamfir, N. V.

    2015-07-01

    Extreme Light Infrastructure-Nuclear Physics (ELI-NP) is aiming to use extreme electromagnetic fields for nuclear physics research. The facility, currently under construction at Magurele-Bucharest, will comprise a high power laser system and a very brilliant gamma beam system. The technology involved in the construction of both systems is at the limits of the present-day's technological capabilities. The high power laser system will consist of two 10 PW lasers and it will produce intensities of up to 1023-1024 W/cm2. The gamma beam, produced via Compton backscattering of a laser beam on a relativistic electron beam, will be characterized by a narrow bandwidth (<0.5%) and tunable energy of up to almost 20 MeV. The research program of the facility covers a broad range of key topics in frontier fundamental physics and new nuclear physics. A particular attention is given to the development of innovative applications. In the present paper an overview of the project status and the overall performance characteristics of the main research equipment will be given. The main fundamental physics and applied research topics proposed to be studied at ELI-NP will also be briefly reviewed.

  18. Extreme Light Infrastructure - Nuclear Physics Eli-Np Project

    NASA Astrophysics Data System (ADS)

    Gales, S.

    2015-06-01

    The development of high power lasers and the combination of such novel devices with accelerator technology has enlarged the science reach of many research fields, in particular High energy, Nuclear and Astrophysics as well as societal applications in Material Science, Nuclear Energy and Medicine. The European Strategic Forum for Research Infrastructures (ESFRI) has selected a proposal based on these new premises called "ELI" for Extreme Light Infrastructure. ELI will be built as a network of three complementary pillars at the frontier of laser technologies. The ELI-NP pillar (NP for Nuclear Physics) is under construction near Bucharest (Romania) and will develop a scientific program using two 10 PW class lasers and a Back Compton Scattering High Brilliance and Intense Low Energy Gamma Beam , a marriage of Laser and Accelerator technology at the frontier of knowledge. In the present paper, the technical description of the facility, the present status of the project as well as the science, applications and future perspectives will be discussed.

  19. Covariant Spectator Theory of np scattering: Isoscalar interaction currents

    SciTech Connect

    Gross, Franz L.

    2014-06-01

    Using the Covariant Spectator Theory (CST), one boson exchange (OBE) models have been found that give precision fits to low energy $np$ scattering and the deuteron binding energy. The boson-nucleon vertices used in these models contain a momentum dependence that requires a new class of interaction currents for use with electromagnetic interactions. Current conservation requires that these new interaction currents satisfy a two-body Ward-Takahashi (WT), and using principals of {\\it simplicity\\/} and {\\it picture independence\\/}, these currents can be uniquely determined. The results lead to general formulae for a two-body current that can be expressed in terms of relativistic $np$ wave functions, ${\\it \\Psi}$, and two convenient truncated wave functions, ${\\it \\Psi}^{(2)}$ and $\\widehat {\\it \\Psi}$, which contain all of the information needed for the explicit evaluation of the contributions from the interaction current. These three wave functions can be calculated from the CST bound or scattering state equations (and their off-shell extrapolations). A companion paper uses this formalism to evaluate the deuteron magnetic moment.

  20. It's not just the "heavy NP": relative phrase length modulates the production of heavy-NP shift.

    PubMed

    Stallings, Lynne M; MacDonald, Maryellen C

    2011-06-01

    Heavy-NP shift is the tendency for speakers to place long direct object phrases at the end of a clause rather than next to the verb. Though some analyses have focused on length of the direct object phrase alone, results from two experiments demonstrate that the length of the direct object relative to that of other phrases, and not the length of the direct object alone, predicts production of the shifted structure. These data support an accessibility-based interpretation of length effects in word order emerging from incremental production processes, in which longer phrases tend to be less easily planned and therefore are delayed during utterance planning.

  1. X-ray Diffraction, Mössbauer Spectroscopy, Magnetic Susceptibility, and Specific Heat Investigations of Na4NpO5 and Na5NpO6.

    PubMed

    Smith, Anna L; Hen, Amir; Raison, Philippe E; Colineau, Eric; Griveau, Jean-Christophe; Magnani, Nicola; Sanchez, Jean-Pierre; Konings, Rudy J M; Caciuffo, Roberto; Cheetham, Anthony K

    2015-05-01

    The hexavalent and heptavalent sodium neptunate compounds Na4NpO5 and Na5NpO6 have been investigated using X-ray powder diffraction, Mössbauer spectroscopy, magnetic susceptibility, and specific heat measurements. Na4NpO5 has tetragonal symmetry in the space group I4/m, while Na5NpO6 adopts a monoclinic unit cell in the space group C2/m. Both structures have been refined for the first time using the Rietveld method. The valence states of neptunium in these two compounds, i.e., Np(VI) and Np(VII), respectively, have been confirmed by the isomer shift values of their Mössbauer spectra. The local structural properties obtained from the X-ray refinements have also been related to the quadrupole coupling constants and asymmetry parameters determined from the Mössbauer studies. The absence of magnetic ordering has been confirmed for Na4NpO5. However, specific heat measurements at low temperatures have suggested the existence of a Schottky-type anomaly at around 7 K in this Np(VI) phase. PMID:25859629

  2. Selective patterned growth of single-crystal organic nanowires of Ag-TCNQ with chemical raction method

    SciTech Connect

    Xiao, Kai; Tao, Jing; Puretzky, Alexander A; Ivanov, Ilia N; Retterer, Scott T; Pennycook, Stephen J; Geohegan, David B

    2008-01-01

    Abstract: We report for the selective-area chemical synthesis of semiconductor single-crystal organic nanowires of silver-tetracyanoquinodimethane (Ag-TCNQ). Straight and smooth Ag-TCNQ nanowires can be produced and patterned on micrometer and nanometer scale on silicon substrates covered with a thin layer of Ag film through the reaction of TCNQ and Ag in a simple gas-solid chemical reaction process. Ag-TCNQ nanowires are characterized by UV-vis, IR and Raman spectroscopy, respectively. The Ag-TCNQ nanowires grows preferentially along the [100] direction of strong - stacking of Ag-TCNQ molecules. Nanodevices based on these nanowires are fabricated using focus ion beam (FIB) technique. Electrical properties are characterized and I-V hysteresis is observed, which shows memory effect with electrical switching of three orders on-off ratio. These nanowires could be potential for use in optical storage, ultrahigh-density nanoscale memory and logic devices.

  3. Highly transparent Au-coated Ag nanowire transparent electrode with reduction in haze.

    PubMed

    Kim, Taegeon; Canlier, Ali; Cho, Changsoon; Rozyyev, Vepa; Lee, Jung-Yong; Han, Seung Min

    2014-08-27

    Ag nanowire transparent electrode has excellent transmittance and sheet resistance, yet its optical haze still needs to be improved in order for it to be suitable for display applications. Ag nanowires are known to have high haze because of the geometry of the nanowire and the high light scattering characteristic of the Ag. In this study, a Au-coated Ag nanowire structure was proposed to reduce the haze, where a thin layer of Au was coated on the surface of the Ag nanowires using a mild [Au(en)2]Cl3 galvanic displacement reaction. The mild galvanic exchange allowed for a thin layer of Au coating on the Ag nanowires with minimal truncation of the nanowire, where the average length and the diameter were 13.0 μm and 60 nm, respectively. The Au-coated Ag nanowires were suspended in methanol and then electrostatically sprayed on a flexible polycarbonate substrate that revealed a clear reduction in haze with a 2-4% increase in total transmittance, sheet resistance ranges of 80-90%, and 8.8-36.8 Ohm/sq. Finite difference time domain simulations were conducted for Au-coated Ag nanowires that indicated a significant reduction in the average scattering from 1 to 0.69 for Au layer thicknesses of 0-10 nm.

  4. Amplified terminal protection assay of small molecule/protein interactions via a highly characteristic solid-state Ag/AgCl process.

    PubMed

    Wang, Qiong; Jiang, Bingying; Xu, Jin; Xie, Jiaqing; Xiang, Yun; Yuan, Ruo; Chai, Yaqin

    2013-05-15

    In this work, we describe a new sensitive strategy for electrochemical detection of protein via small molecule/protein interactions. This assay is based on a terminal protection mechanism that small molecule-linked single-stranded DNA (ssDNA) is protected against hydrolysis by exonuclease I when the target protein is captured by the corresponding small molecule recognition element. Positively charged gold nanoparticles (AuNPs) are attached to the termini-protected and negatively charged ssDNA through electrostatic interactions. Subsequent AuNP-catalyzed silver enhancement followed by a highly characteristic and sensitive solid-state Ag/AgCl process is introduced to the sensing platform to amplify the signal output. By combining the amplification ability resulting from the silver deposition on the surface-captured AuNPs with the inherent high sensitivity of the electrochemical solid-state Ag/AgCl process, our method expands its range to the detection of macromolecules that bind to specific small molecules and enables low picomolar detection of protein. As a model of biotin/streptavidin interaction, a detection limit of 10 pM for streptavidin is readily achieved with desirable sensitivity and specificity, which indicates that the terminal protection assay coupled with the electrochemical solid-state Ag/AgCl process can offer a promising platform for the determination of various of types of proteins or small molecule-protein interactions.

  5. Ab initio energetics for modeling phase stability of the Np-U system

    NASA Astrophysics Data System (ADS)

    Xie, Wei; Chang, Y. Austin; Morgan, Dane

    2016-10-01

    The Np-U system has been rarely studied despite this alloy being a key binary subsystem of metallic nuclear fuels. This study aims to further the understanding of the phase stability of the Np-U system through ab initio calculations. We first examined an existing CALPHAD model based on available experimental phase boundary data. We then focused on phases of which the CALPHAD model reproduces reasonably the experimental data and examined if values of the effective Hubbard U (i.e., Ueff) parameter for Np and U fitted previously in the Np-Zr and U-Zr systems are also applicable to the Np-U system, using CALPHAD predicted enthalpies as references. We found that in general DFT + U predicts improved or at least similarly accurate enthalpies compared to standard DFT when the Ueff's used are within the ranges of single-structure optimized Ueff's (0.65-0.9 eV for Np and 1-1.5 eV for U)-for example, the multi-structure optimized Ueff's (0.9 eV for Np and 1.24 eV for U)-determined in our previous U-Zr and Np-Zr studies. Finally, we focused on the intermediate phase ζ(Np,U), which at present is poorly characterized by experiments and unsatisfactorily described in the CALPHAD model. Based on ab initio calculated formation enthalpies for ordered end members and the compound energy formalism, we predicted its site occupations as functions of composition and temperature. Our study demonstrated that Ueff's fitted for U and Np determined in the U-Zr and Np-Zr systems may be transferable to the Np-U system and also provided new prediction of the site occupations for ζ(Np,U), which may serve as reference for future experimental and modeling study of the Np-U system.

  6. Ag Division States Philosophy

    ERIC Educational Resources Information Center

    American Vocational Journal, 1976

    1976-01-01

    The discussion which took place during the American Vocational Association's (AVA) Agriculture Division meeting at the 1975 AVA Convention is summarized, and the statement of vo-ag education philosophy (including 13 key concepts), which was passed during the convention, is presented. (AJ)

  7. Aminated polyethersulfone-silver nanoparticles (AgNPs-APES) composite membranes with controlled silver ion release for antibacterial and water treatment applications.

    PubMed

    Haider, M Salman; Shao, Godlisten N; Imran, S M; Park, Sung Soo; Abbas, Nadir; Tahir, M Suleman; Hussain, Manwar; Bae, Wookeun; Kim, Hee Taik

    2016-05-01

    The present study reports the antibacterial disinfection properties of a series of silver nanoparticle (AgNP) immobilized membranes. Initially, polyethersulfone (PES) was functionalized through the introduction of amino groups to form aminated polyethersulfone (NH2-PES, APES). AgNPs were then coordinately immobilized on the surface of the APES composite membrane to form AgNPs-APES. The properties of the obtained membrane were examined by FT-IR, XPS, XRD, TGA, ICP-OES and SEM-EDAX analyses. These structural characterizations revealed that AgNPs ranging from 5 to 40 nm were immobilized on the surface of the polymer membrane. Antibacterial tests of the samples showed that the AgNPs-APES exhibited higher activity than the AgNPs-PES un-functionalized membrane. Generally, the AgNPs-APES 1 cm × 3 cm strip revealed a four times longer life than the un-functionalized AgNPs polymer membranes. The evaluation of the Ag(+) leaching properties of the obtained samples indicated that approximately 30% of the AgNPs could be retained, even after 12 days of operation. Further analysis indicated that silver ion release can be sustained for approximately 25 days. The present study provides a systematic and novel approach to synthesize water treatment membranes with controlled and improved silver (Ag(+)) release to enhance the lifetime of the membranes.

  8. Freeze-dried PVP-Ag+ precursors to novel AgBr/AgCl-Ag hybrid nanocrystals for visible-light-driven photodegradation of organic pollutants

    NASA Astrophysics Data System (ADS)

    Chen, Deliang; Chen, Qianqian; Zhang, Wenjie; Ge, Lianfang; Shao, Gang; Fan, Bingbing; Lu, Hongxia; Zhang, Rui; Yang, Daoyuan; Shao, Guosheng

    2015-04-01

    AgBr/AgCl-Ag nanocrystals with various molar Br-to-Ag ratios (RBr/Ag = 0, 1/3, 1/2, 2/3, 1) and different photoreduction times (0-20 min) were synthesized via stepwise liquid-solid reactions using the freeze-dried PVP-Ag+ hybrid as the Ag source, followed by a photoreduction reaction. The AgBr/AgCl-Ag7.5(1:2) nanocrystals obtained take on a spherical morphology with a particle-size range of 58 ± 15 nm. The photocatalytic performance of AgBr/AgCl-Ag nanocrystals was evaluated by photodegrading organic dyes, 4-chlorophenol and isopropanol under artificial visible light (λ ⩾ 420 nm, 100 mW cm-2). For the decomposition of rhodamine B, the AgBr/AgCl-Ag7.5(1:2) nanocrystals has a photodegradation rate of ∼0.87 min-1, ∼159 times higher than that (∼0.0054 min-1) of TiO2 (P25), whereas the AgCl-Ag and AgBr-Ag nanocrystals have photodegradation rates of 0.35 min-1 and 0.45 min-1, respectively. The efficient separation of photogenerated electron-hole pairs in the ternary system consisting of AgBr, AgCl and Ag species plays a key role in the enhancement of photocatalytic performance.

  9. AGS experiments -- 1995, 1996 and 1997

    SciTech Connect

    Depken, J.C.; Presti, P.L.

    1997-12-01

    This report contains (1) FY 1995 AGS schedule as run; (2) FY 1996 AGS schedule as run; (3) FY 1997 AGS schedule as run; (4) FY 1998--1999 AGS schedule (proposed); (5) AGS beams 1997; (6) AGS experimental area FY 1995 physics program; (7) AGS experimental area FY 1996 physics program; (8) AGS experimental area FY 1997 physics program; (9) AGS experimental area FY 1998--1999 physics program (proposed); (10) a listing of experiments by number; (11) two-page summaries of each experiment, in order by number; and (12) listing of publications of AGS experiments.

  10. AGS experiments -- 1991, 1992, 1993. Tenth edition

    SciTech Connect

    Depken, J.C.

    1994-04-01

    This report contains: (1) FY 1993 AGS schedule as run; (2) FY 1994--95 AGS schedule; (3) AGS experiments {ge} FY 1993 (as of 30 March 1994); (4) AGS beams 1993; (5) AGS experimental area FY 1991 physics program; (6) AGS experimental area FY 1992 physics program; (7) AGS experimental area FY 1993 physics program; (8) AGS experimental area FY 1994 physics program (planned); (9) a listing of experiments by number; (10) two-page summaries of each experiment; (11) listing of publications of AGS experiments; and (12) listing of AGS experiments.

  11. Study of thermodynamic properties of Np-Al alloys in molten LiCl-KCl eutectic

    NASA Astrophysics Data System (ADS)

    Souček, P.; Malmbeck, R.; Mendes, E.; Nourry, C.; Sedmidubský, D.; Glatz, J.-P.

    2009-10-01

    Pyrochemical methods are investigated worldwide within the framework of Partitioning and Transmutation concepts for spent nuclear fuel reprocessing. Electroseparation techniques in a molten LiCl-KCl are being developed in ITU to recover all actinides from a mixture with fission products. During the process, actinides are selectively electrochemically reduced on a solid aluminium cathode, forming solid actinide-aluminium alloys. This work is focused on the thermodynamic properties of Np-Al alloys in a temperature range of 400-550 °C and on the characterisation of the structure and chemical composition of deposits obtained by electrodeposition of Np on solid Al electrodes in a LiCl-KCl-NpCl 3 melt. Cyclic voltammetry and open circuit chronopotentiometry have been used to examine the electrochemical behaviour of Np on inert W and reactive Al electrodes. Gibbs energies, enthalpy and entropy of formation and standard electrode potentials of Np-Al alloys were evaluated and compared with ab initio calculations. Galvanostatic electrolyses at 450 °C were carried out to recover Np onto Al plates and the solid surface deposits were characterised by XRD and SEM-EDX analyses. Stable and dense deposits consisting of NpAl 3 and NpAl 4 alloys were identified. In addition, the conversion of NpO 2 to NpCl 3 is described, using chlorination of the oxide in a molten salt media by pure chlorine gas.

  12. Antifungal activity of transparent nanocomposite thin films of pullulan and silver against Aspergillus niger.

    PubMed

    Pinto, Ricardo J B; Almeida, Adelaide; Fernandes, Susana C M; Freire, Carmen S R; Silvestre, Armando J D; Neto, Carlos Pascoal; Trindade, Tito

    2013-03-01

    Silver has been mainly investigated as an antibacterial agent and less as a fungicide in which concerns antimicrobial properties. In this research, the antifungal activity of composite films of pullulan and Ag nanoparticles (NP) against Aspergillus niger was evaluated using standard protocols. These new materials were prepared as transparent cast films (66-74 μm thickness) from Ag hydrosols containing the polysaccharide. Fungal growth inhibition was observed in the presence of such silver nanocomposite films. Moreover, disruption of the spores cells of A. niger was probed for the first time by means of scanning electron microscopy (SEM). This effect occurred in the presence of the nanocomposites due to Ag NP dispersed as fillers in pullulan. This polysaccharide was used here as a biocompatible matrix, hence making these nanocomposites beneficial for the development of antifungal packaging materials.

  13. Exclusive µ+Np topologies with ArgoNeuT

    SciTech Connect

    Partyka, Kinga

    2015-05-15

    The Argon Neutrino Test, ArgoNeuT, is a small scale Liquid Argon Time Projection Chamber (LAr TPC) that is one step towards the construction of large scale LAr TPCs for long-baseline neutrino physics. LArTPCs provide bubble-chamber-like quality images for excellent particle ID and background rejection. Due to its superb capabilities it is well suited for topological analysis by reporting what it sees in a final state. Preliminary analysis of ArgoNeuT’s 0.1 to 10 GeV neutrino µ+Np topologies together with first ever study of proton multiplicities in neutrino-argon interactions was presented and compared with GENIE Monte Carlo generator.

  14. NP-hardness of decoding quantum error-correction codes

    SciTech Connect

    Hsieh, Min-Hsiu; Le Gall, Francois

    2011-05-15

    Although the theory of quantum error correction is intimately related to classical coding theory and, in particular, one can construct quantum error-correction codes (QECCs) from classical codes with the dual-containing property, this does not necessarily imply that the computational complexity of decoding QECCs is the same as their classical counterparts. Instead, decoding QECCs can be very much different from decoding classical codes due to the degeneracy property. Intuitively, one expects degeneracy would simplify the decoding since two different errors might not and need not be distinguished in order to correct them. However, we show that general quantum decoding problem is NP-hard regardless of the quantum codes being degenerate or nondegenerate. This finding implies that no considerably fast decoding algorithm exists for the general quantum decoding problems and suggests the existence of a quantum cryptosystem based on the hardness of decoding QECCs.

  15. Destabilization of Ag nanoislands on Ag(100) by adsorbed sulfur

    SciTech Connect

    Shen, Mingmin; Russell, Selena M.; Liu, Da-Jiang; Thiel, Patricia A.

    2011-10-17

    Sulfur accelerates coarsening of Ag nanoislands on Ag(100) at 300 K, and this effect is enhanced with increasing sulfur coverage over a range spanning a few hundredths of a monolayer, to nearly 0.25 monolayers. We propose that acceleration of coarsening in this system is tied to the formation of AgS{sub 2} clusters primarily at step edges. These clusters can transport Ag more efficiently than can Ag adatoms (due to a lower diffusion barrier and comparable formation energy). The mobility of isolated sulfur on Ag(100) is very low so that formation of the complex is kinetically limited at low sulfur coverages, and thus enhancement is minimal. However, higher sulfur coverages force the population of sites adjacent to step edges, so that formation of the cluster is no longer limited by diffusion of sulfur across terraces. Sulfur exerts a much weaker effect on the rate of coarsening on Ag(100) than it does on Ag(111). This is consistent with theory, which shows that the difference between the total energy barrier for coarsening with and without sulfur is also much smaller on Ag(100) than on Ag(111).

  16. High-value utilization of lignin to synthesize Ag nanoparticles with detection capacity for Hg²⁺.

    PubMed

    Shen, Zuguang; Luo, Yuqiong; Wang, Qun; Wang, Xiaoying; Sun, Runcang

    2014-09-24

    This study reports the rapid preparation of silver nanoparticles (AgNPs) from Tollens' reagent under microwave irradiation. In the synthesis, lignin with reducing groups and spatial three-dimensional structure was used as reducing and stabilizing agents without other chemical reagents, and the effects of the ratio of lignin to Ag(+), reaction temperature, and heating time on the synthesis of AgNPs were investigated. The obtained AgNPs were further characterized by UV-vis, Malvern particle size, TEM, XRD, and XPS analyses. The structural changes of lignin before and after reaction were also studied by FT-IR, (1)H NMR, (13)C NMR, and GC-MS. The results revealed that the obtained AgNPs were mostly spherical with diameters of around 24 nm. The optimum reaction conditions were a ratio 50 mg of lignin to 0.3 mM of Ag(+), a microwave irradiation temperature of 60 °C, and a heating time of 10 min. Moreover, AgNPs redispersed well in water and ethanol after centrifugation for the removal of lignin. During the formation of AgNPs, lignin was oxidized, and the side chains of lignin were partly disrupted into small molecules, such as hydrocarbon and alcohol. The resultant lignin-AgNPs showed highly selective sensing detection for Hg(2+), and the color of the lignin-AgNP solution containing Hg(2+) decreased gradually with increasing amounts of Hg(2+) within seconds, but the other 19 metal ions had little effect on the color and surface plasmon absorption band of the lignin-AgNPs. Also, there was a linear relationship between the absorbance and Hg(2+) concentration, with a limit of detection concentration of 23 nM. This study provides not only a new way to take advantage of agricultural and forestry residues, but also a green and rapid method for the synthesis of AgNPs to detect the toxic ion Hg(2+) selectively and sensitively.

  17. NXT1, a Novel Influenza A NP Binding Protein, Promotes the Nuclear Export of NP via a CRM1-Dependent Pathway

    PubMed Central

    Chutiwitoonchai, Nopporn; Aida, Yoko

    2016-01-01

    Influenza remains a serious worldwide public health problem. After infection, viral genomic RNA is replicated in the nucleus and packed into viral ribonucleoprotein, which will then be exported to the cytoplasm via a cellular chromosome region maintenance 1 (CRM1)-dependent pathway for further assembly and budding. However, the nuclear export mechanism of influenza virus remains controversial. Here, we identify cellular nuclear transport factor 2 (NTF2)-like export protein 1 (NXT1) as a novel binding partner of nucleoprotein (NP) that stimulates NP-mediated nuclear export via the CRM1-dependent pathway. NXT1-knockdown cells exhibit decreased viral replication kinetics and nuclear accumulated viral RNA and NP. By contrast, NXT1 overexpression promotes nuclear export of NP in a CRM1-dependent manner. Pull-down assays suggest the formation of an NXT1, NP, and CRM1 complex, and demonstrate that NXT1 binds to the C-terminal region of NP. These findings reveal a distinct mechanism for nuclear export of the influenza virus and identify the NXT1/NP interaction as a potential target for antiviral drug development. PMID:27483302

  18. NXT1, a Novel Influenza A NP Binding Protein, Promotes the Nuclear Export of NP via a CRM1-Dependent Pathway.

    PubMed

    Chutiwitoonchai, Nopporn; Aida, Yoko

    2016-01-01

    Influenza remains a serious worldwide public health problem. After infection, viral genomic RNA is replicated in the nucleus and packed into viral ribonucleoprotein, which will then be exported to the cytoplasm via a cellular chromosome region maintenance 1 (CRM1)-dependent pathway for further assembly and budding. However, the nuclear export mechanism of influenza virus remains controversial. Here, we identify cellular nuclear transport factor 2 (NTF2)-like export protein 1 (NXT1) as a novel binding partner of nucleoprotein (NP) that stimulates NP-mediated nuclear export via the CRM1-dependent pathway. NXT1-knockdown cells exhibit decreased viral replication kinetics and nuclear accumulated viral RNA and NP. By contrast, NXT1 overexpression promotes nuclear export of NP in a CRM1-dependent manner. Pull-down assays suggest the formation of an NXT1, NP, and CRM1 complex, and demonstrate that NXT1 binds to the C-terminal region of NP. These findings reveal a distinct mechanism for nuclear export of the influenza virus and identify the NXT1/NP interaction as a potential target for antiviral drug development.

  19. Selective photochemical synthesis of Ag nanoparticles on position-controlled ZnO nanorods for the enhancement of yellow-green light emission

    NASA Astrophysics Data System (ADS)

    Park, Hyeong-Ho; Zhang, Xin; Lee, Keun Woo; Sohn, Ahrum; Kim, Dong-Wook; Kim, Joondong; Song, Jin-Won; Choi, Young Su; Lee, Hee Kwan; Jung, Sang Hyun; Lee, In-Geun; Cho, Young-Dae; Shin, Hyun-Beom; Sung, Ho Kun; Park, Kyung Ho; Kang, Ho Kwan; Park, Won-Kyu; Park, Hyung-Ho

    2015-12-01

    A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to preferentially form Ag NPs on ZnO nanorods. The ratio of visible emission to ultraviolet (UV) emission for the Ag NP-decorated ZnO nanorod arrays, synthesized for 30 min, is 20.5 times that for the ZnO nanorod arrays without Ag NPs. The enhancement of the visible emission is believed to associate with the surface plasmon (SP) effect of Ag NPs. The Ag NP-decorated ZnO nanorod arrays show significant SP-induced enhancement of yellow-green light emission, which could be useful in optoelectronic applications. The technique developed here requires low processing temperatures (120 °C and lower) and no high-vacuum deposition tools, suitable for applications such as flexible electronics.A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to

  20. AGS preinjector improvement

    SciTech Connect

    Alessi, J.G.; Brennan, J.M.; Brown, H.N.; Brodowski, J.; Gough, R.; Kponou, A.; Prelec, K.; Staples, J.; Tanabe, J.; Witkover, R.

    1987-01-01

    In 1984, a polarized H/sup -/ source was installed to permit the acceleration of polarized protons in the AGS, using a low current, 750 keV RFQ Linear Accelerator as the preinjector. This RFQ was designed by LANL and has proved to be quite satisfactory and reliable. In order to improve the reliability and simplify maintenance of the overall AGS operations, it has been decided to replace one of the two 750 keV Cockcroft-Waltons (C-W) with an RFQ. The design of a new high current RFQ has been carried out by LBL and is also being constructed there. This paper describes the preinjector improvement project, centered around that RFQ, which is underway at BNL.

  1. Optical band gap of NpO2 and PuO2 from optical absorbance of epitaxial films

    NASA Astrophysics Data System (ADS)

    Mark McCleskey, T.; Bauer, Eve; Jia, Quanxi; Burrell, Anthony K.; Scott, Brian L.; Conradson, Steven D.; Mueller, Alex; Roy, Lindsay; Wen, Xiaodong; Scuseria, Gustavo E.; Martin, Richard L.

    2013-01-01

    We report a solution based synthesis of epitaxial thin films of neptunium oxide and plutonium oxide. Actinides represent a challenge to first principle calculations due to features that arise from f orbital interactions. Conventional semi-local density functional theory predicts NpO2 and PuO2 to be metallic, when they are well known insulators. Improvements in theory are dependent on comparison with accurate measurements of material properties, which in turn demand high-quality samples. The high melting point of actinide oxides and their inherent radioactivity makes single crystal and epitaxial film formation challenging. We report on the preparation of high quality epitaxial actinide films. The films have been characterized through a combination of X-ray diffraction and X-ray absorption fine structure (XANES and EXAFS) measurements. We report band gaps of 2.80 ± 0.1 eV and 2.85 ± 0.1 eV at room temperature for PuO2 and NpO2, respectively, and compare our measurements with state-of-the-art calculations.

  2. Tumor suppressor WWOX binds to ΔNp63α and sensitizes cancer cells to chemotherapy

    PubMed Central

    Salah, Z; Bar-mag, T; Kohn, Y; Pichiorri, F; Palumbo, T; Melino, G; Aqeilan, R I

    2013-01-01

    The WWOX tumor suppressor is a WW domain-containing protein. Its function in the cell has been shown to be mediated, in part, by interacting with its partners through its first WW (WW1) domain. Here, we demonstrated that WWOX via WW1 domain interacts with p53 homolog, ΔNp63α. This protein–protein interaction stabilizes ΔNp63α, through antagonizing function of the E3 ubiquitin ligase ITCH, inhibits nuclear translocation of ΔNp63α into the nucleus and suppresses ΔNp63α transactivation function. Additionally, we found that this functional crosstalk reverses cancer cells resistance to cisplatin, mediated by ΔNp63α, and consequently renders these cells more sensitive to undergo apoptosis. These findings suggest a functional crosstalk between WWOX and ΔNp63α in tumorigenesis. PMID:23370280

  3. Submicron patterns obtained by thermal-induced reconstruction of self-assembled monolayer of Ag nanoparticles and their application in SERS

    NASA Astrophysics Data System (ADS)

    Ruan, Weidong; Zhou, Tieli; Cui, Yinqiu; Dong, Yujie; Liu, Zhuo; Dong, Fengxia; Wang, Haiyang; Luan, Xintong; Wang, Xu; Song, Wei; Zhao, Bing

    2014-08-01

    The layer-by-layer (LbL) self-assembly technique was employed for the deposition of poly(diallyldimethylammonium chloride) (PDDA) and triangular Ag nanoplates on glass substrates. A thermal-induced reconstruction of these polyelectrolyte-linked nanoparticle (NP) films was presented. Before the reconstruction, triangular Ag nanoplates were distributed uniformly on the surface with an average interval of 50 ± 15 nm. After the reconstruction, the triangular Ag nanoplates accumulated into discrete stacks with an average interval of 90 ± 25 nm. The temperature-dependent experiments were done and the optimal temperature for the formation of the reconstructed patterns was 120 °C. The possible mechanism of the NP movement and stacking was analyzed. Under the experimental conditions, a hydrophobic environment was formed because of the vacuum and heating. As a result the polyelectrolyte-linked Ag NPs preferred to congregate due to the lowered surface energy. Finally the submicron patterns were formed. The ultraviolet-visible (UV-vis) absorption and surface-enhanced Raman scattering (SERS) properties of the films before and after the reconstruction was investigated. The reconstructed films with submicron patterns had better SERS enhancement ability, which was 1300 times to the original films. The reconstruction method of the monolayer films showed great potential in the surface design and related applications. AFM images were obtained to clarify the three dimensional structures of the reconstructed films obtained at 120 °C. As shown in Fig. 2, the Ag NP stacks had an average diameter of 1.0 ± 0.2 μm and an average height of 170 ± 30 nm. The diameter and height of the stacks were shaped by the aggregates of tens of triangular Ag nanoplates. The AFM cross-sectional contour showed the clear intervals of the stacks, which was corresponding to the SEM characterization.XRD patterns of the polyelectrolyte-linked NP films before and after thermal post-treatment are showed in

  4. The effect of silver nanoparticles (AgNPs) on proliferation and apoptosis of in ovo cultured glioblastoma multiforme (GBM) cells

    NASA Astrophysics Data System (ADS)

    Urbańska, Kaja; Pająk, Beata; Orzechowski, Arkadiusz; Sokołowska, Justyna; Grodzik, Marta; Sawosz, Ewa; Szmidt, Maciej; Sysa, Paweł

    2015-03-01

    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.

  5. 3D-stacked Ag nanowires for efficient plasmonic light absorbers and SERS sensors

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Ho; Mun, ChaeWon; Lee, MinKyoung; Park, Sung-Gyu

    2016-04-01

    We report new 3D hybrid plasmonic nanostructures exhibiting highly sensitive SERS-based sensing performance, utilizing efficient plasmonic light absorption and analyte-enrichment effect. The hybrid plasmonic nanostructures composed of 3D-stacked Ag NWs and NPs separated by a thin hydrophobic dielectric interlayer. A hydrophobic polydimethylsiloxane (PDMS) interlayer provides dielectric nanogap between Ag NWs and NPs, and analyte-enrichment effect due to the inhibition of drop spreading. The 3D hybrid PDMS-interlayered Ag nanostructures showed hydrophobicity with initial contact angle of 137.6°. Utilizing the analyte-enrichment strategy, the PDMS-interlayered Ag nanostructures exhibited an enhanced sensitivity of methylene blue molecules by a factor of 10 (limit of detection, LOD of 1.5 nM), compared to the alumina-separated 3D hybrid Ag nanostructures.

  6. Ag nanoparticle-ZnO nanowire hybrid nanostructures as enhanced and robust antimicrobial textiles via a green chemical approach.

    PubMed

    Li, Zhou; Tang, Haoying; Yuan, Weiwei; Song, Wei; Niu, Yongshan; Yan, Ling; Yu, Min; Dai, Ming; Feng, Siyu; Wang, Menghang; Liu, Tengjiao; Jiang, Peng; Fan, Yubo; Wang, Zhong Lin

    2014-04-11

    A new approach for fabrication of a long-term and recoverable antimicrobial nanostructure/textile hybrid without increasing the antimicrobial resistance is demonstrated. Using in situ synthesized Ag nanoparticles (NPs) anchored on ZnO nanowires (NWs) grown on textiles by a 'dip-in and light-irradiation' green chemical method, we obtained ZnONW@AgNP nanocomposites with small-size and uniform Ag NPs, which have shown superior performance for antibacterial applications. These new Ag/ZnO/textile antimicrobial composites can be used for wound dressings and medical textiles for topical and prophylactic antibacterial treatments, point-of-use water treatment to improve the cleanliness of water and antimicrobial air filters to prevent bioaerosols accumulating in ventilation, heating, and air-conditioning systems.

  7. Ag nanoparticle-ZnO nanowire hybrid nanostructures as enhanced and robust antimicrobial textiles via a green chemical approach

    NASA Astrophysics Data System (ADS)

    Li, Zhou; Tang, Haoying; Yuan, Weiwei; Song, Wei; Niu, Yongshan; Yan, Ling; Yu, Min; Dai, Ming; Feng, Siyu; Wang, Menghang; Liu, Tengjiao; Jiang, Peng; Fan, Yubo; Wang, Zhong Lin

    2014-04-01

    A new approach for fabrication of a long-term and recoverable antimicrobial nanostructure/textile hybrid without increasing the antimicrobial resistance is demonstrated. Using in situ synthesized Ag nanoparticles (NPs) anchored on ZnO nanowires (NWs) grown on textiles by a ‘dip-in and light-irradiation’ green chemical method, we obtained ZnONW@AgNP nanocomposites with small-size and uniform Ag NPs, which have shown superior performance for antibacterial applications. These new Ag/ZnO/textile antimicrobial composites can be used for wound dressings and medical textiles for topical and prophylactic antibacterial treatments, point-of-use water treatment to improve the cleanliness of water and antimicrobial air filters to prevent bioaerosols accumulating in ventilation, heating, and air-conditioning systems.

  8. NP24 induces apoptosis dependent on caspase-like activity in Saccharomyces cerevisiae.

    PubMed

    Higuchi, Naoki; Ito, Yasuhiro; Kato, Jun; Ogihara, Jun; Kasumi, Takafumi

    2016-06-01

    Tomato NP24 is a homolog of osmotin, a PR-5 protein from tobacco that can initiate apoptosis in yeast via PHO36 in the plasma membrane. We cloned and sequenced NP24 from tomato cv. Momotaro. Based on phylogenetic analysis, NP24 from Momotaro belonged to the Solanaceae clade. The amino acid sequence was identical to that of cv. Ailsa Craig including signal peptide, but the residues predicted to interact with the adiponectin receptor, ADIPOR, were slightly different from osmotin. Recombinant NP24 (rNP24) was expressed in a reductase-deficient mutant of Escherichia coli as host cell, and purified from cell extract by affinity chromatography. Purified rNP24 significantly inhibited growth of Saccharomyces cerevisiae wild-type spheroplasts. In contrast, growth of PHO36 deletion mutant (ΔIzh2) spheroplasts was not inhibited. Moreover, rNP24 induced significant activity of reactive oxygen species, caspase-like activity, and also nuclear fragmentation in wild-type spheroplast cells. These results demonstrated that rNP24 from Momotaro greatly influenced cell viability due to triggering apoptosis through PHO36. Notably, apoptosis induced by NP24 was caspase-like protease dependent.

  9. Unusual electric field gradient variation in the NpPd2Ge2 compound

    NASA Astrophysics Data System (ADS)

    Gaczyński, P.; Colineau, E.; Wastin, F.; Boulet, P.; Rebizant, J.; Caciuffo, R.

    2011-01-01

    NpPd2Ge2 has been studied by 237Np Mössbauer spectroscopy between 4.2 K and 80 K. The value of the isomer shift suggests a Np3+ electronic configuration. The low temperature spectra provide a value of 2.10 μB for the magnetic ordered moment on the Np site. These values suggest a rather localized character of the 5f electrons in this system. The magnetic transition around 60 K is accompanied by a large increase of the quadrupolar interaction that is evidence of a redistribution of the electronic charges around the neptunium nucleus.

  10. Controls on the Fate and Speciation of Np(V) During Iron (Oxyhydr)oxide Crystallization.

    PubMed

    Bots, Pieter; Shaw, Samuel; Law, Gareth T W; Marshall, Timothy A; Mosselmans, J Frederick W; Morris, Katherine

    2016-04-01

    The speciation and fate of neptunium as Np(V)O2(+) during the crystallization of ferrihydrite to hematite and goethite was explored in a range of systems. Adsorption of NpO2(+) to iron(III) (oxyhydr)oxide phases was reversible and, for ferrihydrite, occurred through the formation of mononuclear bidentate surface complexes. By contrast, chemical extractions and X-ray absorption spectroscopy (XAS) analyses showed the incorporation of Np(V) into the structure of hematite during its crystallization from ferrihydrite (pH 10.5). This occurred through direct replacement of octahedrally coordinated Fe(III) by Np(V) in neptunate-like coordination. Subsequent analyses on mixed goethite and hematite crystallization products (pH 9.5 and 11) showed that Np(V) was incorporated during crystallization. Conversely, there was limited evidence for Np(V) incorporation during goethite crystallization at the extreme pH of 13.3. This is likely due to the formation of a Np(V) hydroxide precipitate preventing incorporation into the goethite particles. Overall these data highlight the complex behavior of Np(V) during the crystallization of iron(III) (oxyhydr)oxides, and demonstrate clear evidence for neptunium incorporation into environmentally important mineral phases. This extends our knowledge of the range of geochemical conditions under which there is potential for long-term immobilization of radiotoxic Np in natural and engineered environments. PMID:26913955

  11. Understanding mNP hyperthermia for cancer treatment at the cellular scale

    NASA Astrophysics Data System (ADS)

    Stigliano, Robert V.; Shubitidze, Fridon; Kekalo, Katsiaryna; Baker, Ian; Giustini, Andrew J.; Hoopes, P. Jack

    2013-02-01

    The use of magnetic nanoparticles (mNP's) to induce local hyperthermia has been emerging in recent years as a promising cancer therapy, in both a stand-alone and combination treatment setting. Studies have shown that cancer cells associate with, internalize, and aggregate mNP's more preferentially than normal cells. Once the mNP's are delivered inside the cells, a low frequency (30 kHz-300 kHz) alternating electromagnetic field is used to activate the mNP's. The nanoparticles absorb the applied field and provide localized heat generation at nano-micron scales. It has been shown experimentally that mNP's exhibit collective behavior when in close proximity. Although most prevailing mNP heating models assume there is no magnetic interaction between particles, our data suggests that magnetic interaction effects due to mNP aggregation are often significant; In the case of multi-crystal core particles, interaction is guaranteed. To understand the physical phenomena responsible for this effect, we modeled electromagnetic coupling between mNP's in detail. The computational results are validated using data from the literature as well as measurements obtained in our lab. The computational model presented here is based on a method of moments technique and is used to calculate magnetic field distributions on the nanometer scale, both inside and outside the mNP.

  12. NP24 induces apoptosis dependent on caspase-like activity in Saccharomyces cerevisiae.

    PubMed

    Higuchi, Naoki; Ito, Yasuhiro; Kato, Jun; Ogihara, Jun; Kasumi, Takafumi

    2016-06-01

    Tomato NP24 is a homolog of osmotin, a PR-5 protein from tobacco that can initiate apoptosis in yeast via PHO36 in the plasma membrane. We cloned and sequenced NP24 from tomato cv. Momotaro. Based on phylogenetic analysis, NP24 from Momotaro belonged to the Solanaceae clade. The amino acid sequence was identical to that of cv. Ailsa Craig including signal peptide, but the residues predicted to interact with the adiponectin receptor, ADIPOR, were slightly different from osmotin. Recombinant NP24 (rNP24) was expressed in a reductase-deficient mutant of Escherichia coli as host cell, and purified from cell extract by affinity chromatography. Purified rNP24 significantly inhibited growth of Saccharomyces cerevisiae wild-type spheroplasts. In contrast, growth of PHO36 deletion mutant (ΔIzh2) spheroplasts was not inhibited. Moreover, rNP24 induced significant activity of reactive oxygen species, caspase-like activity, and also nuclear fragmentation in wild-type spheroplast cells. These results demonstrated that rNP24 from Momotaro greatly influenced cell viability due to triggering apoptosis through PHO36. Notably, apoptosis induced by NP24 was caspase-like protease dependent. PMID:26589784

  13. Core-size-dependent catalytic properties of bimetallic Au/Ag core-shell nanoparticles.

    PubMed

    Haldar, Krishna Kanta; Kundu, Simanta; Patra, Amitava

    2014-12-24

    Bimetallic core-shell nanoparticles have recently emerged as a new class of functional materials because of their potential applications in catalysis, surface enhanced Raman scattering (SERS) substrate and photonics etc. Here, we have synthesized Au/Ag bimetallic core-shell nanoparticles with varying the core diameter. The red-shifting of the both plasmonic peaks of Ag and Au confirms the core-shell structure of the nanoparticles. Transmission electron microscopy (TEM) analysis, line scan EDS measurement and UV-vis study confirm the formation of core-shell nanoparticles. We have examined the catalytic activity of these core-shell nanostructures in the reaction between 4-nitrophenol (4-NP) and NaBH4 to form 4-aminophenol (4-AP) and the efficiency of the catalytic reaction is found to be increased with increasing the core size of Au/Ag core-shell nanocrystals. The catalytic efficiency varies from 41.8 to 96.5% with varying core size from 10 to 100 nm of Au/Ag core-shell nanoparticles, and the Au100/Ag bimetallic core-shell nanoparticle is found to be 12-fold more active than that of the pure Au nanoparticles with 100 nm diameter. Thus, the catalytic properties of the metal nanoparticles are significantly enhanced because of the Au/Ag core-shell structure, and the rate is dependent on the size of the core of the nanoparticles.

  14. Charge Separation and Catalytic Activity of Fe3 O4 @Ag "Nanospheres".

    PubMed

    Hemmateenejad, Bahram; Shamsipur, Mojtaba; Jalili-Jahani, Naser

    2016-01-01

    Nanospheres of Ag-coated Fe3 O4 were successfully synthesized and characterized. Photocatalytic properties of Fe3 O4 @Ag composites have been investigated using steady-state studies and laser pulse excitations. Accumulation of the electrons in the Ag shell was detected from the shift in the surface plasmon band from 430 to 405 nm, which was discharged when an electron acceptor such as O2 , Thionine (TH) or C60 was introduced into the system. Charge equilibration with redox couple such as C60 (●-) /C60 indicated the ability of these core-shell structures to carry out photocatalytic reduction reactions. As well, outer Ag layer could boost charge separation in magnetic core through dual effects of Schottky junction and localized surface plasmonic resonance (LSPR)-powered band gap breaking effect under sunlight irradiation; resulted in higher photocatalytic degradation of diphenylamine (DPA). The maximum photocatalytic degradation rate was achieved at optimum amount of Ag-NP loading to products. Adsorption studies confirmed that degradation of DPA dominantly occurred in solution. Moderately renewability of the nanocatalysts under sunlight was due to oxidation and dissolution of the outer Ag layer.

  15. Ag Nanoparticle-Grafted PAN-Nanohump Array Films with 3D High-Density Hot Spots as Flexible and Reliable SERS Substrates.

    PubMed

    Li, Zhongbo; Meng, Guowen; Huang, Qing; Hu, Xiaoye; He, Xuan; Tang, Haibin; Wang, Zhiwei; Li, Fadi

    2015-10-28

    A facile fabrication approach of large-scale flexible films is reported, with one surface side consisting of Ag-nanoparticle (Ag-NP) decorated polyacrylonitrile (PAN) nanohump (denoted as Ag-NPs@PAN-nanohump) arrays. This is achieved via molding PAN films with ordered nanohump arrays on one side and then sputtering much smaller Ag-NPs onto each of the PAN-nanohumps. Surface-enhanced Raman scattering (SERS) activity of the Ag-NPs@PAN-nanohump array films can be improved by curving the flexible PAN film with ordered nanohump arrays during the Ag-sputtering process to increase the density of the Ag-NPs on the sidewalls of the PAN-nanohumps. More 3D hot spots are thus achieved on a large-scale. The Ag-NPs@PAN-nanohump array films show high SERS activity with good Raman signal reproducibility for Rhodamine 6G probe molecules. To trial their practical application, the Ag-NPs@PAN-nanohump array films are employed as SERS substrates for trace detection of trinitrotoluene and a congener of polychlorinated biphenyls. A lower detection limit of 10(-12) m and 10(-5) m can be achieved, respectively. Furthermore, the flexible Ag-NPs@PAN-nanohump array films can also be utilized as swabs to probe traces of methyl parathion on the surface of fruits such as apples. The as-fabricated SERS substrates therefore have promising potential for applications in rapid safety inspection and environmental protection.

  16. Hollow Au/Ag nanostars displaying broad plasmonic resonance and high surface-enhanced Raman sensitivity

    NASA Astrophysics Data System (ADS)

    Garcia-Leis, Adianez; Torreggiani, Armida; Garcia-Ramos, Jose Vicente; Sanchez-Cortes, Santiago

    2015-08-01

    Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars. The size, shape, and composition of Ag as well as their optical properties were studied by extinction spectroscopy, hyperspectral dark field microscopy, transmission and scanning electron microscopy (TEM and SEM), and energy dispersive X-ray spectroscopy (EDX). Finally, the surface-enhanced Raman scattering (SERS) activity of these HNS was investigated by using thioflavin T, a biomarker of the β-amyloid fibril formation, responsible for Alzheimer's disease. Lucigenin, a molecule displaying different SERS activities on Au and Ag, was also used to explore the presence of these metals on the NP surface. Thus, a relationship between the morphology, plasmon resonance and SERS activity of these new NPs was made.Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars

  17. Ag doped silicon nitride nanocomposites for embedded plasmonics

    NASA Astrophysics Data System (ADS)

    Bayle, M.; Bonafos, C.; Benzo, P.; Benassayag, G.; Pécassou, B.; Khomenkova, L.; Gourbilleau, F.; Carles, R.

    2015-09-01

    The localized surface plasmon-polariton resonance (LSPR) of noble metal nanoparticles (NPs) is widely exploited for enhanced optical spectroscopies of molecules, nonlinear optics, photothermal therapy, photovoltaics, or more recently in plasmoelectronics and photocatalysis. The LSPR frequency depends not only of the noble metal NP material, shape, and size but also of its environment, i.e., of the embedding matrix. In this paper, Ag-NPs have been fabricated by low energy ion beam synthesis in silicon nitride (SiNx) matrices. By coupling the high refractive index of SiNx to the relevant choice of dielectric thickness in a SiNx/Si bilayer for an optimum antireflective effect, a very sharp plasmonic optical interference is obtained in mid-range of the visible spectrum (2.6 eV). The diffusion barrier property of the host SiNx matrix allows for the introduction of a high amount of Ag and the formation of a high density of Ag-NPs that nucleate during the implantation process. Under specific implantation conditions, in-plane self-organization effects are obtained in this matrix that could be the result of a metastable coarsening regime.

  18. Ag doped silicon nitride nanocomposites for embedded plasmonics

    SciTech Connect

    Bayle, M.; Bonafos, C. Benzo, P.; Benassayag, G.; Pécassou, B.; Carles, R.; Khomenkova, L.; Gourbilleau, F.

    2015-09-07

    The localized surface plasmon-polariton resonance (LSPR) of noble metal nanoparticles (NPs) is widely exploited for enhanced optical spectroscopies of molecules, nonlinear optics, photothermal therapy, photovoltaics, or more recently in plasmoelectronics and photocatalysis. The LSPR frequency depends not only of the noble metal NP material, shape, and size but also of its environment, i.e., of the embedding matrix. In this paper, Ag-NPs have been fabricated by low energy ion beam synthesis in silicon nitride (SiN{sub x}) matrices. By coupling the high refractive index of SiN{sub x} to the relevant choice of dielectric thickness in a SiN{sub x}/Si bilayer for an optimum antireflective effect, a very sharp plasmonic optical interference is obtained in mid-range of the visible spectrum (2.6 eV). The diffusion barrier property of the host SiN{sub x} matrix allows for the introduction of a high amount of Ag and the formation of a high density of Ag-NPs that nucleate during the implantation process. Under specific implantation conditions, in-plane self-organization effects are obtained in this matrix that could be the result of a metastable coarsening regime.

  19. Surface plasmon resonance in nanostructured Ag incorporated ZnS films

    SciTech Connect

    Chalana, S. R.; Mahadevan Pillai, V. P.; Ganesan, V.

    2015-10-15

    Silver incorporated zinc sulfide thin films are prepared by RF magnetron sputtering technique and the influence of silver incorporation on the structural, optical and luminescence properties is analyzed using techniques like grazing incidence X-Ray diffraction (GIXRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), micro-Raman spectroscopy, UV-Vis spectroscopy and laser photoluminescence spectroscopy. XRD analysis presents hexagonal wurtzite structure for the films. A reduction of crystallinity of the films is observed due to Ag incorporation. The Raman spectral analysis confirms the reduction of crystallinity and increase of strain due to the Ag incorporation. AFM analysis reveals a rough surface morphology for the undoped film and Ag incorporation makes the films uniform, dense and smooth. A blue shift of band gap energy with increase in Ag incorporation is observed due to quantum confinement effect. An absorption band (450-650 nm region) due to surface plasmon resonance of the Ag clusters present in the ZnS matrix is observed for the samples with higher Ag incorporation. The complex dielectric constant, loss factor and distribution of volume and surface energy loss of the ZnS thin films are calculated. Laser photoluminescence measurements gives an intense bluish green emission from the ZnS films and a quenching of the PL emission is observed which can be due to the metal plasmonic absorption and non-radiative energy transfer due to Ag incorporation.

  20. Highly luminescent material based on Alq3:Ag nanoparticles.

    PubMed

    Salah, Numan; Habib, Sami S; Khan, Zishan H

    2013-09-01

    Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices. PMID:23653126

  1. Mechanically reinforced {1 1 0} <1 1 0> textured Ag/Ni-alloys composite substrates for low-cost coated conductors

    NASA Astrophysics Data System (ADS)

    Suo, Hongli; Genoud, Jean-Yves; Caracino, Paola; Spreafico, Sergio; Schindl, Michael; Walker, Eric; Flükiger, René

    2002-08-01

    New, reinforced {1 1 0} <1 1 0> textured Ag/Ni-alloys composite ribbons were developed as possible substrates for coated conductors without any buffer layer. The texture quality and tensile strength were investigated. A new technique to bond the Ag and Ni or alloy layers through a Cu foil was presented. The Ag/Ni-alloys composite ribbons were fabricated by choosing proper sintering processing to bond the different layers followed by cold rolling and recrystallization. A thin Cu foil was intercalated between the initial Ag and Ni or alloy pieces to get a tough bond. A unique and stable {1 1 0} <1 1 0> annealing texture was obtained in 300 μm thick Ag/Ni composite ribbon after annealing. X-ray ODF analysis and EBSD measurements in the top Ag layer showed distribution of misorientation angles around 10-15°. A {1 1 0} <1 1 0> texture was also found in ribbons as thin as 50 μm, which cannot be obtained with pure Ag ribbons. A pronounced reduction of Ag amount was obtained in 60 μm thick Ag/NiCrV ribbons, with a textured Ag top layer being as thin as 7 μm. The amount of Ag was decreased by 75% compared to pure Ag ribbons of the same thickness. A strong enhancement of the mechanical properties was observed. The yield strength σ0.2 at 77 K was 220 MPa for Ag/NiCrV ribbons, i.e. considerably higher than the 30 MPa for pure Ag ribbons.

  2. Evaluating the blue-shift behaviors of the surface plasmon coupling of an embedded light emitter with a surface Ag nanoparticle by adding a dielectric interlayer or coating.

    PubMed

    Kuo, Yang; Chang, Wen-Yen; Lin, Chun-Han; Yang, C C; Kiang, Yean-Woei

    2015-11-30

    The surface plasmon (SP) coupling behaviors of an embedded light emitter or radiating dipole in GaN with a surface Ag nanoparticle (NP) in four structures of different added dielectric geometries, including an extended dielectric interlayer (DI) and a DI of a finite width between the Ag NP and GaN, a dielectric coating on the Ag NP, and no dielectric addition, are numerically compared. Either an added DI or dielectric coating can lead to the blue shift of localized surface plasmon (LSP) dipole resonance peak or the spectral peak of radiated power enhancement ratio with respect to that of the structure without dielectric addition. A smaller dielectric refractive-index or a larger dielectric thickness results in a larger blue-shift range. Under the condition of the same dielectric refractive-index and thickness, the structure of a DI with a finite width leads to the largest blue-shift range, followed by the structure of an extended DI and then the structure of a dielectric coating. In a practical application, for a given emission wavelength of a blue-emitting quantum well, the emission enhancement effect through SP coupling depends on the LSP resonance strength at this wavelength. Our study also shows that although the LSP resonance peak can be blue-shifted by reducing the size of a surface Ag NP, its SP coupling strength is dramatically reduced. Adding a DI or dielectric coating is a more practical approach for shifting the major LSP resonance mode of a surface Ag NP from the green into blue range.

  3. Performance and temperature dependencies of proton irradiated n/p and p/n GaAs and n/p silicon cells

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.

    1985-01-01

    n/p homojunction GaAs cells are found to be more radiation resistant than p/n heteroface GaAs under 10 MeV proton irradiation. Both GaAs cell types outperform conventional silicon n/p cells under the same conditions. An increased temperature dependency of maximum power for the GaAs n/p cells is attributed to differences in Voc between the two GaAs cell types. These results and diffusion length considerations are consistent with the conclusion that p-type GaAs is more radiation resistant than n-type and therefore that the n/p configuration is possibly favored for use in the space radiation environment. However, it is concluded that additional work is required in order to choose between the two GaAs cell configurations.

  4. The Signal Transfer from the Receptor NpSRII to the Transducer NpHtrII Is Not Hampered by the D75N Mutation

    PubMed Central

    Holterhues, Julia; Bordignon, Enrica; Klose, Daniel; Rickert, Christian; Klare, Johann P.; Martell, Swetlana; Li, Lin; Engelhard, Martin; Steinhoff, Heinz-Jürgen

    2011-01-01

    Sensory rhodopsin II (NpSRII) is a phototaxis receptor of Natronomonas pharaonis that performs its function in complex with its cognate transducer (NpHtrII). Upon light activation NpSRII triggers by means of NpHtrII a signal transduction chain homologous to the two component system in eubacterial chemotaxis. The D75N mutant of NpSRII, which lacks the blue-shifted M intermediate and therefore exhibits a significantly faster photocycle compared to the wild-type, mediates normal phototaxis responses demonstrating that deprotonation of the Schiff base is not a prerequisite for transducer activation. Using site-directed spin labeling and time resolved electron paramagnetic-resonance spectroscopy, we show that the mechanism revealed for activation of the wild-type complex, namely an outward tilt motion of the cytoplasmic part of the receptor helix F and a concomitant rotation of the transmembrane transducer helix TM2, is also valid for the D75N variant. Apparently, the D75N mutation shifts the ground state conformation of NpSRII-D75N and its cognate transducer into the direction of the signaling state. PMID:21539797

  5. Ag-nanoparticles on UF-microsphere as an ultrasensitive SERS substrate with unique features for rhodamine 6G detection.

    PubMed

    Hao, Zhixian; Mansuer, Mulati; Guo, Yuqing; Zhu, Zhirong; Wang, Xiaogang

    2016-01-01

    Urea and formaldehyde (UF) microsphere (MS) adsorbing Ag nanoparticles (NPs) was employed as a surface enhanced Raman scattering (SERS) substrate for rhodamine 6G (R6G) detection. The UF MSs and citrate-reduced Ag colloid supplying Ag NPs are synthesized separately and all the subsequent fabrication procedure is then implemented within 2 mL centrifuge tube. Influences of the composition and drying temperature of the UF MSs and the drying method and modification of AgNP/UFMS on the final SERS performance have first been reported. Excess formaldehyde useful in the formation of UF MSs again plays an important role in the SERS detection. Some interesting phenomena in the approach, such as swelling/deswelling of UF MSs and R6G diffusion within hydrophilic environment of UF MSs, are found to be of variable factors affecting the SERS performance. The substrate AgNP/UFMS confidently achieves a detection limit of 10(-13) M R6G and can be used as a simple and effective platform in the SERS spectroscopy. PMID:26695301

  6. Hyperspectral reflected light microscopy of plasmonic Au/Ag alloy nanoparticles incubated as multiplex chromatic biomarkers with cancer cells.

    PubMed

    Patskovsky, Sergiy; Bergeron, Eric; Rioux, David; Simard, Mikaël; Meunier, Michel

    2014-10-21

    A hyperspectral microscopy system based on a reflected light method for plasmonic nanoparticle (NP) imaging was designed and compared with a conventional darkfield method for spatial localization and spectroscopic identification of single Au, Ag and Au/Ag alloy NPs incubated with fixed human cancer cell preparations. A new synthesis protocol based on co-reduction of Au and Ag salts combined with the seeded growth technique was used for the fabrication of monodispersed alloy NPs with sizes ranging from 30 to 100 nm in diameter. We validated theoretically and experimentally the performance of 60 nm Au, Ag and Au/Ag (50 : 50) NPs as multiplexed biological chromatic markers for biomedical diagnostics and optical biosensing. The advantages of the proposed reflected light microscopy method are presented for NP imaging in a complex and highly diffusing medium such as a cellular environment. The obtained information is essential for the development of a high throughput, selective and efficient strategy for cancer detection and treatment. PMID:25133743

  7. Intensification of surface enhanced Raman scattering of thiol-containing molecules using Ag@Au core@shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Singh, Prerna; Thuy, Nguyen T. B.; Aoki, Yoshiya; Mott, Derrick; Maenosono, Shinya

    2011-05-01

    In this paper, we study the relationship between nanoparticles' structure/composition and the chemical nature of the molecules to be identified in surface enhanced Raman scattering (SERS) spectroscopy. Three types of nanoparticles (NPs) were synthesized, including Ag, Au, and silver coated by gold (Ag@Au), in order to study the resulting enhancement effects. When a rhodamine 6G dye molecule was used to assemble the NPs, it was found that Ag NPs exhibited the highest enhancement activity. However, when a thiol containing 3-amino-1,2,4-triazole-5-thiol molecule was used to assemble the NPs, it was found that the Ag@Au NPs exhibited high Raman activity as well as the Ag NPs. The results give insight into how the chemical properties of the molecules to be analyzed play an important role in the SERS detection. An additional parameter of the analysis reveals the relative stability of the three types of NP probes synthesized with regard to oxidation in the presence of different mediating molecules and varying salt concentrations. The results are of interest in designing and employing NP probes to detect biological molecules using colorimetric and SERS based approaches.

  8. Ag-nanoparticles on UF-microsphere as an ultrasensitive SERS substrate with unique features for rhodamine 6G detection.

    PubMed

    Hao, Zhixian; Mansuer, Mulati; Guo, Yuqing; Zhu, Zhirong; Wang, Xiaogang

    2016-01-01

    Urea and formaldehyde (UF) microsphere (MS) adsorbing Ag nanoparticles (NPs) was employed as a surface enhanced Raman scattering (SERS) substrate for rhodamine 6G (R6G) detection. The UF MSs and citrate-reduced Ag colloid supplying Ag NPs are synthesized separately and all the subsequent fabrication procedure is then implemented within 2 mL centrifuge tube. Influences of the composition and drying temperature of the UF MSs and the drying method and modification of AgNP/UFMS on the final SERS performance have first been reported. Excess formaldehyde useful in the formation of UF MSs again plays an important role in the SERS detection. Some interesting phenomena in the approach, such as swelling/deswelling of UF MSs and R6G diffusion within hydrophilic environment of UF MSs, are found to be of variable factors affecting the SERS performance. The substrate AgNP/UFMS confidently achieves a detection limit of 10(-13) M R6G and can be used as a simple and effective platform in the SERS spectroscopy.

  9. Removal of 4-Nitrophenol from Water Using Ag-N-P-Tridoped TiO2 by Photocatalytic Oxidation Technique.

    PubMed

    Achamo, Temesgen; Yadav, O P

    2016-01-01

    Photocatalytic oxidation using semiconductor nanoparticles is an efficient, eco-friendly, and cost-effective process for the removal of organic pollutants, such as dyes, pesticides, phenols, and their derivatives in water. In the present study, nanosize Ag-N-P-tridoped titanium(IV) oxide (TiO2) was prepared by using sol-gel-synthesized Ag-doped TiO2 and soybean (Glycine max) or chickpea (Cicer arietinum) seeds as nonmetallic bioprecursors. As-synthesized photocatalysts were characterized using X-ray diffraction, Fourier transform infrared, and ultra violet (UV)-visible spectroscopic techniques. Average crystallite size of the studied photocatalysts was within 39-46 nm. Whereas doped Ag in TiO2 minimized the photogenerated electron-hole recombination, doped N and P extended its photoabsorption edge to visible region. Tridoping of Ag, N, and P in TiO2 exhibited synergetic effect toward enhancing its photocatalytic degradation of 4-nitrophenol (4-NP), separately, under UV and visible irradiations. At three hours, degradations of 4-NP over Ag-N-P-tridoped TiO2 under UV and visible radiations were 73.8 and 98.1%, respectively.

  10. Removal of 4-Nitrophenol from Water Using Ag-N-P-Tridoped TiO2 by Photocatalytic Oxidation Technique.

    PubMed

    Achamo, Temesgen; Yadav, O P

    2016-01-01

    Photocatalytic oxidation using semiconductor nanoparticles is an efficient, eco-friendly, and cost-effective process for the removal of organic pollutants, such as dyes, pesticides, phenols, and their derivatives in water. In the present study, nanosize Ag-N-P-tridoped titanium(IV) oxide (TiO2) was prepared by using sol-gel-synthesized Ag-doped TiO2 and soybean (Glycine max) or chickpea (Cicer arietinum) seeds as nonmetallic bioprecursors. As-synthesized photocatalysts were characterized using X-ray diffraction, Fourier transform infrared, and ultra violet (UV)-visible spectroscopic techniques. Average crystallite size of the studied photocatalysts was within 39-46 nm. Whereas doped Ag in TiO2 minimized the photogenerated electron-hole recombination, doped N and P extended its photoabsorption edge to visible region. Tridoping of Ag, N, and P in TiO2 exhibited synergetic effect toward enhancing its photocatalytic degradation of 4-nitrophenol (4-NP), separately, under UV and visible irradiations. At three hours, degradations of 4-NP over Ag-N-P-tridoped TiO2 under UV and visible radiations were 73.8 and 98.1%, respectively. PMID:27081309

  11. Low energy scattering cross section ratios of 14N(p ,p ) 14N

    NASA Astrophysics Data System (ADS)

    deBoer, R. J.; Bardayan, D. W.; Görres, J.; LeBlanc, P. J.; Manukyan, K. V.; Moran, M. T.; Smith, K.; Tan, W.; Uberseder, E.; Wiescher, M.; Bertone, P. F.; Champagne, A. E.; Islam, M. S.

    2015-04-01

    Background: The slowest reaction in the first CNO cycle is 14N(p ,γ ) 15O , therefore its rate determines the overall energy production efficiency of the entire cycle. The cross section presents several strong resonance contributions, especially for the ground-state transition. Some of the properties of the corresponding levels in the 15O compound nucleus remain uncertain, which affects the uncertainty in extrapolating the capture cross section to the low energy range of astrophysical interest. Purpose: The 14N(p ,γ ) 15O cross section can be described by using the phenomenological R matrix. Over the energy range of interest, only the proton and γ -ray channels are open. Since resonance capture makes significant contributions to the 14N(p ,γ ) 15O cross section, resonant proton scattering data can be used to provide additional constraints on the R -matrix fit of the capture data. Methods: A 4 MV KN Van de Graaff accelerator was used to bombard protons onto a windowless gas target containing enriched 14N gas over the proton energy range from Ep=1.0 to 3.0 MeV. Scattered protons were detected at θlab=90 , 120∘, 135∘, 150∘, and 160∘ using ruggedized silicon detectors. In addition, a 10 MV FN Tandem Van de Graaff accelerator was used to accelerate protons onto a solid Adenine (C5H5N5 ) target, of natural isotopic abundance, evaporated onto a thin self-supporting carbon backing, over the energy range from Ep=1.8 to 4.0 MeV. Scattered protons were detected at 28 angles between θlab=30 .4∘ and 167 .7∘ by using silicon photodiode detectors. Results: Relative cross sections were extracted from both measurements. While the relative cross sections do not provide as much constraint as absolute measurements, they greatly reduce the dependence of the data on otherwise significant systematic uncertainties, which are more difficult to quantify. The data are fit simultaneously using an R -matrix analysis and level energies and proton widths are extracted. Even

  12. Effects of silver nanoparticles with different sizes on photochemical responses of polythiophene-fullerene thin films.

    PubMed

    You, Jing; Leonard, Kwati; Takahashi, Yukina; Yonemura, Hiroaki; Yamada, Sunao

    2014-01-21

    Effects of size and coverage density of silver nanoparticles (AgPs) on the fluorescence emission and fluorescence lifetime of poly(3-hexylthiophene-2,5-diyl) (P3HT) thin films were investigated. AgPs of 64 nm diameter showed greater effects on the fluorescence decay process of P3HT films as compared with 7 nm AgPs. The fluorescence lifetime (FL) of P3HT decreased from 0.61 to 0.22 ns in the presence of 64 nm AgPs, while no appreciable change (0.60 ns) was seen in the case of 7 nm AgPs. The results suggest that the 64 nm AgPs showed a greater effect on the enhancement of the decay rate of excited P3HT. The photoelectric conversion of thin films consisting of P3HT and phenyl-C61-butyric acid methyl ester (PCBM) was also investigated. AgPs of 7 or 64 nm diameters were first deposited on indium-tin-oxide substrates with controlled surface coverage densities from ~1 to 40%. When the coverage densities of deposited AgPs were ~20% for both 7 and 64 nm, the enhancement of photoelectric conversion efficiency reached maximum. The degree of enhancement in the case of 64 nm AgPs was larger than in the case of 7 nm AgPs. PMID:24292622

  13. Spectroscopic investigation of U, Np and Th in nuclear glasses

    NASA Astrophysics Data System (ADS)

    Calas, G.; Galoisy, L. V.; Petit-Maire, D.

    2011-12-01

    Vitrification of high-level radioactive waste in borosilicate glasses is currently used on an industrial scale in several countries. The fundamental properties of the waste forms are their chemical and mechanical durability against the forcing conditions represented by chemical alteration or internal/external irradiation. The waste immobilized in glass is composed of over 30 different nuclear fission and activation products, as well as minor actinides. The oxidation state and local atomic coordination of long-lived radionuclides are important parameters to understand the long-term evolution of the glass. We present an overview of the local structure around actinides in glasses similar to the French nuclear glass. X-Ray absorption spectroscopy has been used to probe the local environment around uranium, neptunium and thorium in these glasses. It is combined with with UV-visible spectroscopy, used to get selective information on the surrounding of U(IV), U(V) and U(VI) in glasses. Our spectroscopic data show that U, Np and Th occur in nuclear glasses in a peculiar surrounding showing significant differences with the crystal chemistry of these elements in crystalline compounds. Element speciation may be used as a pertinent parameter to follow the long-term stability of nuclear glasses, either under irradiation or during the alteration of the glass.

  14. Surface modification of nanoporous alumina layers by deposition of Ag nanoparticles. Effect of alumina pore diameter on the morphology of silver deposit and its influence on SERS activity

    NASA Astrophysics Data System (ADS)

    Pisarek, Marcin; Nowakowski, Robert; Kudelski, Andrzej; Holdynski, Marcin; Roguska, Agata; Janik-Czachor, Maria; Kurowska-Tabor, Elżbieta; Sulka, Grzegorz D.

    2015-12-01

    Self-organized Al2O3 nanoporous/nanotubular (Al2O3-NP) oxide layers decorated with silver nanoparticles (Ag-NPs) exhibiting specific properties may serve as attractive SERS substrates for investigating the interactions between an adsorbate and adsorbent, or as stable platforms for detecting various organic compounds. This article presents the influence of the size of the alumina nanopores with a deposit of silver nanoparticles obtained by the magnetron sputtering technique on the morphology of silver film. Moreover, the effect of pore diameter on the intensity of SERS spectra in Ag-NPs/Al2O3-NP/Al composites has also been estimated. For such investigations we used pyridine as a probe molecule, since it has a large cross-section for Raman scattering. To characterize the morphology of the composite oxide layer Ag-NPs/Al2O3-NP/Al, before and after deposition of Ag-NPs by PVD methods (Physical Vapor Deposition), we used scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface analytical technique of surface-enhanced Raman spectroscopy (SERS) was used to investigate the surface activity of the composite. The results obtained show that, for a carefully controlled amount of Ag (0.020 mg/cm2 - deposited on the top of alumina nanopores whose average size varies from ∼86 nm up to ∼320 nm) in the composites investigated, pore size significantly affects SERS enhancement. We obtained distinctly higher intensities of SERS spectra for substrates with an Ag-NPs deposit having a larger diameter of the alumina nanopores. AFM results suggest that both the lateral and perpendicular distribution of Ag-NPs within and on the top of the largest pores is responsible for the highest SERS activity of the resulting Ag-NPs/Al2O3-NP/Al composite layer, since it produces a variety of cavities and slits which function as resonators for the adsorbed molecules. The Ag-NPs/MeOx-NP/Me composite layers obtained ensure a good reproducibility of the SERS measurements. a

  15. Ag-Air Service

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Econ, Inc.'s agricultural aerial application, "ag-air," involves more than 10,000 aircraft spreading insecticides, herbicides, fertilizer, seed and other materials over millions of acres of farmland. Difficult for an operator to estimate costs accurately and decide what to charge or which airplane can handle which assignment most efficiently. Computerized service was designed to improve business efficiency in choice of aircraft and determination of charge rates based on realistic operating cost data. Each subscriber fills out a detailed form which pertains to his needs and then receives a custom-tailored computer printout best suited to his particular business mix.

  16. Simultaneous determination of epinephrine and dopamine by electrochemical reduction on the hybrid material SiO₂/graphene oxide decorated with Ag nanoparticles.

    PubMed

    Cincotto, Fernando H; Canevari, Thiago C; Campos, Anderson M; Landers, Richard; Machado, Sérgio A S

    2014-09-21

    This paper describes the synthesis, characterization and applications of a new hybrid material composed of mesoporous silica (SiO2) modified with graphene oxide (GO), SiO2/GO, obtained by the sol-gel process using HF as the catalyst. The hybrid material, SiO2/GO, was decorated with silver nanoparticles (AgNPs) with a size of less than 20 nanometres, prepared directly on the surface of the material using N,N-dimethylformamide (DMF) as the reducing agent. The resulting material was designated as AgNP/SiO2/GO. The Ag/SiO2/GO material was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and high-resolution transmission electron microscopy (HR-TEM). A glassy carbon electrode modified with AgNP/SiO2/GO was used in the development of a sensitive electrochemical sensor for the simultaneous determination of epinephrine and dopamine employing electrocatalytic reduction using squarewave voltammetry. Well-defined and separate reduction peaks were observed in PBS buffer at pH 7. No significant interference was seen for primarily biological interferents such as uric acid and ascorbic acid in the detection of dopamine and epinephrine. Our study demonstrated that the resultant AgNP/SiO2/GO-modified electrode is highly sensitive for the simultaneous determination of dopamine and epinephrine, with the limits of detection being 0.26 and 0.27 μmol L(-1), respectively. The AgNP/SiO2/GO-modified electrode is highly selective and can be used to detect dopamine and epinephrine in a human urine sample.

  17. Mechanical properties of nanoporous GaN and its application for separation and transfer of GaN thin films.

    PubMed

    Huang, Shanjin; Zhang, Yu; Leung, Benjamin; Yuan, Ge; Wang, Gang; Jiang, Hao; Fan, Yingmin; Sun, Qian; Wang, Jianfeng; Xu, Ke; Han, Jung

    2013-11-13

    Nanoporous (NP) gallium nitride (GaN) as a new class of GaN material has many interesting properties that the conventional GaN material does not have. In this paper, we focus on the mechanical properties of NP GaN, and the detailed physical mechanism of porous GaN in the application of liftoff. A decrease in elastic modulus and hardness was identified in NP GaN compared to the conventional GaN film. The promising application of NP GaN as release layers in the mechanical liftoff of GaN thin films and devices was systematically studied. A phase diagram was generated to correlate the initial NP GaN profiles with the as-overgrown morphologies of the NP structures. The fracture toughness of the NP GaN release layer was studied in terms of the voided-space-ratio. It is shown that the transformed morphologies and fracture toughness of the NP GaN layer after overgrowth strongly depends on the initial porosity of NP GaN templates. The mechanical separation and transfer of a GaN film over a 2 in. wafer was demonstrated, which proves that this technique is useful in practical applications.

  18. Communication: Structure, formation, and equilibration of ensembles of Ag-S complexes on an Ag surface

    SciTech Connect

    Russell, Selena M.; Kim, Yousoo; Liu, Da-Jiang; Evans, J. W.; Thiel, P. A.

    2013-02-15

    We have utilized conditions of very low temperature (4.7 K) and very low sulfur coverage to isolate and identify Ag-S complexes that exist on the Ag(111) surface. The experimental conditions are such that the complexes form at temperatures above the temperature of observation. These complexes can be regarded as polymeric chains of varying length, with an Ag4S pyramid at the core of each monomeric unit. Steps may catalyze the formation of the chains and this mechanism may be reflected in the chain length distribution.

  19. Photocatalytic activity of ZnO doped with Ag on the degradation of endocrine disrupting under UV irradiation and the investigation of its antibacterial activity

    NASA Astrophysics Data System (ADS)

    Bechambi, Olfa; Chalbi, Manel; Najjar, Wahiba; Sayadi, Sami

    2015-08-01

    Ag-doped ZnO photocatalysts with different Ag molar content (0.0, 0.5, 1.0, 2.0 and 4.0%) were prepared via hydrothermal method. The X-ray diffraction (XRD), Nitrogen physisorption at 77 K, Fourier transformed infrared spectroscopy (FTIR), UV--Visible spectroscopy, Photoluminescence spectra (PL) and Raman spectroscopy were used to characterize the structural, textural and optical properties of the samples. The results showed that Ag-doping does not change the average crystallite size with the Ag low content (≤1.0%) but slightly decreases with Ag high content (>1.0%). The specific surface area (SBET) increases with the increase of the Ag content. The band gap values of ZnO are decreased with the increase of the Ag doping level. The results of the photocatalytic degradation of bisphenol A (BPA) and nonylphenol (NP) in aqueous solutions under UV irradiation and in the presence of hydrogen peroxide (H2O2) showed that silver ions doping greatly improved the photocatalytic efficiency of ZnO. The TOC conversion BPA and NP are 72.1% and 81.08% respectively obtained using 1% Ag-doped ZnO. The enhancement of photocatalytic activity is ascribed to the fact that the modification of ZnO with an appropriate amount of Ag can increase the separation efficiency of the photogenerated electrons-holes in ZnO. The antibacterial activity of the catalysts which uses Escherichia coli as a model for Gram-negative bacteria confirmed that Ag-doped ZnO possessed more antibacterial activity than the pure ZnO.

  20. The Ebola Virus VP30-NP Interaction Is a Regulator of Viral RNA Synthesis

    PubMed Central

    Kirchdoerfer, Robert N.; Moyer, Crystal L.; Abelson, Dafna M.; Saphire, Erica Ollmann

    2016-01-01

    Filoviruses are capable of causing deadly hemorrhagic fevers. All nonsegmented negative-sense RNA-virus nucleocapsids are composed of a nucleoprotein (NP), a phosphoprotein (VP35) and a polymerase (L). However, the VP30 RNA-synthesis co-factor is unique to the filoviruses. The assembly, structure, and function of the filovirus RNA replication complex remain unclear. Here, we have characterized the interactions of Ebola, Sudan and Marburg virus VP30 with NP using in vitro biochemistry, structural biology and cell-based mini-replicon assays. We have found that the VP30 C-terminal domain interacts with a short peptide in the C-terminal region of NP. Further, we have solved crystal structures of the VP30-NP complex for both Ebola and Marburg viruses. These structures reveal that a conserved, proline-rich NP peptide binds a shallow hydrophobic cleft on the VP30 C-terminal domain. Structure-guided Ebola virus VP30 mutants have altered affinities for the NP peptide. Correlation of these VP30-NP affinities with the activity for each of these mutants in a cell-based mini-replicon assay suggests that the VP30-NP interaction plays both essential and inhibitory roles in Ebola virus RNA synthesis. PMID:27755595

  1. Superior antibacterial activity of GlcN-AuNP-GO by ultraviolet irradiation.

    PubMed

    Govindaraju, Saravanan; Samal, Monica; Yun, Kyusik

    2016-12-01

    A complete bacterialysis analysis of glucosamine-gold nanoparticle-graphene oxide (GlcN-AuNP-GO) and UV-irradiated GlcN-AuNP-GO was conducted. Analytical characterization of GlcN-AuNPs, GO and GlcN-AuNP-GO revealed UV-Vis absorbance peak at around 230 and 500nm. Microscopic characterization of prepared nanomaterials was performed by scanning electron microscope, atomic force microscopy, and high-resolution transmission microscopy. The results confirmed that the GlcN-AuNPs were uniformly decorated on the surface and edges of graphene sheets. In addition, potent antibacterial activity of GlcN-AuNP-GO that was UV irradiated for 10min and normal GlcN-AuNP-GO was detected, compared to the standard drug kanamycin, against both Gram-negative and positive bacteria. The minimum inhibitory concentration (MIC) and fluorescence intensity spectra results for Escherichia coli and Enterococcus faecalis showed that the UV-irradiated GlcN-AuNP-GO has better antibacterial activity than normal GlcN-AuNP-GO and kanamycin. Morphological changes were detected by AFM after treatment. These results confirmed that GlcN-AuNP-GO is a potent antibacterial agent with good potential for use in manufacturing medical instruments, pharmaceutical industries and in waste water treatment. PMID:27612724

  2. Faculty supervision of NP program practicums: A comparison of rural and urban site differences.

    PubMed

    Kaplan, Louise; Klein, Tracy; Skillman, Susan; Andrilla, C Holly

    2016-06-16

    Results of a survey of NP education programs were analyzed to describe factors influencing clinical placement of students in rural clinical rotations, methods used to evaluate NP students in their clinical rotations, and whether the frequency and type of faculty evaluations differed by urban or rural clinical sites. PMID:27327427

  3. Radiochemical determination of 237NP in soil samples contaminated with weapon grade plutonium

    NASA Astrophysics Data System (ADS)

    Antón, M. P.; Espinosa, A.; Aragón, A.

    2006-01-01

    The Palomares terrestrial ecosystem (Spain) constitutes a natural laboratory to study transuranics. This scenario is partially contaminated with weapon-grade plutonium since the burnout and fragmentation of two thermonuclear bombs accidentally dropped in 1966. While performing radiometric measurements in the field, the possible presence of 237Np was observed through its 29 keV gamma emission. To accomplish a detailed characterization of the source term in the contaminated area using the isotopic ratios Pu-Am-Np, the radiochemical isolation and quantification by alpha spectrometry of 237Np was initiated. The selected radiochemical procedure involves separation of Np from Am, U and Pu with ionic resins, given that in soil samples from Palomares 239+240Pu levels are several orders of magnitude higher than 237Np. Then neptunium is isolated using TEVA organic resins. After electrodeposition, quantification is performed by alpha spectrometry. Different tests were done with blank solutions spiked with 236Pu and 237Np, solutions resulting from the total dissolution of radioactive particles and soil samples. Results indicate that the optimal sequential radionuclide separation order is Pu-Np, with decontamination percentages obtained with the ionic resins ranging from 98% to 100%. Also, the addition of NaNO2 has proved to be necessary, acting as a stabilizer of Pu-Np valences.

  4. Location of influenza virus M, NP and NS1 proteins in microinjected cells.

    PubMed

    Davey, J; Colman, A; Dimmock, N J

    1985-11-01

    When microinjected as cloned DNA, the nucleoprotein (NP) of influenza virus A/NT/60/68 (H3N2) accumulated in the nuclei of Xenopus laevis oocytes, and cultured cells of rodent and primate origin. This accumulation appeared to be specific and a property of the NP itself (or conceivably NP in association with unknown cellular constituents) since no other influenza virus components were present in DNA-injected cells. In the oocyte nucleus, clonally derived NP achieved an eightfold concentration over that in the cytoplasm. Such NP was full-length as judged by its mobility during PAGE and had the native conformation of H3N2 virus NP according to its reaction with a panel of monoclonal antibodies. NP appeared to be in the soluble fraction of the nucleus as it did not sediment under conditions which removed particulate matter from nuclear extracts. Microinjection of extracts of chick embryo fibroblast cells infected with A/FPV/Rostock/34 (H7N1) showed that exogenous NP had an affinity for the nucleus similar to that synthesized intracellularly from cloned NP DNA. This conclusion was supported by an experiment in which cloned NP from the oocyte nucleus re-entered the nucleus after injection into the cytoplasm of fresh oocytes. Injection of mRNA, extracted from chick embryo fibroblast cells infected with A/FPV/Rostock/34, into oocytes directed the synthesis of the viral proteins M (Mr 28 000), and NS1 (Mr 27 000) as well as NP (Mr 56 000). While NP from this source concentrated in the nucleus as before, M merely associated with the nucleus without exceeding the cytoplasmic level. Even more remarkable was NS1; although in injected cells this protein is concentrated in nucleoli, in microinjected oocytes its nuclear concentration was threefold less than that in the cytoplasm, despite the very large number (greater than 1500) of nucleoli present in Xenopus oocytes. It seems likely that the karyophilic nature of M and NS1, unlike that of NP, is a property not of the proteins

  5. An ultrathin, smooth, and low-loss Al-doped Ag film and its application as a transparent electrode in organic photovoltaics.

    PubMed

    Zhang, Cheng; Zhao, Dewei; Gu, Deen; Kim, Hyunsoo; Ling, Tao; Wu, Yi-Kuei Ryan; Guo, L Jay

    2014-08-27

    An ultrathin, smooth, and low-loss Ag film without a wetting layer is achieved by co-depositing a small amount of Al into Ag. The film can be as thin as 6 nm, with a roughness below 1 nm and excellent mechanical flexibility. Organic photovoltaics that use these thin films as transparent electrode show superior efficiency to their indium tin oxide (ITO) counterparts because of improved photon management. PMID:24943876

  6. STABILITY CONSTANTS OF NP(V) COMPLEXES WITH FLOURIDE AND SULFATE AT VARIABLE TEMPERATURES

    SciTech Connect

    Y. Xia; J.I. Friese; D.A. Moore; L. Rao

    2005-07-11

    A solvent extraction method was used to determine the stability constants of Np(V) complexes with fluoride and sulfate in 1.0 M NaClO{sub 4} from 25 C to 60 C. The distribution ratio of Np(V) between the organic and aqueous phases was found to decrease as the concentrations of fluoride and sulfate were increased. Stability constants of the 1:1 Np(V)-fluoride complexes and the 1:1 Np(V)-sulfate and 1:2 Np(V)-sulfate complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of [F{sup -}] and [SO{sub 4}{sup 2-}] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures by using the Van't Hoff equation.

  7. The nuclear data, A key component for reactor studies, Overview of AREVA NP needs and applications

    NASA Astrophysics Data System (ADS)

    Ravaux, Simon; Demy, Pierre-Marie; Rechatin, Clément

    2016-03-01

    The quality of the nuclear data is essential for AREVA NP. Indeed, many AREVA NP activities such as reactor design, safety studies or reactor instrumentation use them as input data. So, the nuclear data can be considered as a key element for AREVA NP. REVA NP's contribution in the improvement of the nuclear data consists in a joint effort with the CEA. It means a financing and a sharing of information which can give an orientation to the future research axis. The aim of this article is to present the industrial point of view from AREVA NP on the research on nuclear data. Several examples of collaborations with the CEA which have resulted in an improvement of the nuclear data are presented.

  8. Anisotropic hybrid organic/inorganic (azopolymer/SiO2 NP) materials with enhanced photoinduced birefringence.

    PubMed

    Nazarova, Dimana; Nedelchev, Lian; Sharlandjiev, Peter; Dragostinova, Violeta

    2013-08-01

    Hybrid materials based on combination of polymers and inorganic nanoparticles (NP) attracted considerable attention in the last decade due to their advantageous electrical, optical, or mechanical properties. Recently, we reported a significant improvement of the photoresponse by doping azopolymers with ZnO NP. To study the influence of the composition of the dopant, in our present work we have synthesized anisotropic organic/inorganic nanocomposite materials by incorporating 5-15 nm sized SiO2 NP in a side-chain azopolymer. As a result we observe an enhancement of the photoinduced birefringence in these composite materials with about 20% compared to the nondoped sample. Additionally, we discuss possible mechanisms leading to this enhancement related with the scattering caused by the NP and the increased mobility of the azochromophores in the vicinity of NP. PMID:23913084

  9. Promising antimicrobial capability of thin film metallic glasses.

    PubMed

    Chu, Y Y; Lin, Y S; Chang, C M; Liu, J-K; Chen, C H; Huang, J C

    2014-03-01

    Thin film metallic glasses (TFMGs) are demonstrated to exhibit excellent surface flatness, high corrosion resistance and satisfactory hydrophobic properties. Moreover, the antimicrobial and biocompatibility abilities of TFMGs are examined and the results are compared with the behavior of pure Ag and 316L stainless steel. Three TFMGs, Al48Ag37Ti15, Zr54Ti35Si11, and Zr59Ti22Ag19, are prepared by sputtering to assess the antimicrobial performance against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, which are the most common nosocomial infection pathogens. Experimental results show that the antimicrobial effect of the Al- or Ag-containing AlAgTi and ZrTiAg TFMGs is similar to that of the pure Ag coating. The ZrTiSi TFMG with no Ag or Al shows poor antimicrobial capability. The physical properties of highly smooth surface and hydrophobic nature alone are not sufficient to result in promising antimicrobial ability. The chemical metal ion release still plays a major role, which should be born in mind in designing biomedical devices.

  10. Local density of unoccupied states in ion-beam-mixed Pd-Ag alloys

    SciTech Connect

    Chae, K.H.; Jung, S.M.; Lee, Y.S.; Whang, C.N.; Jeon, Y.; Croft, M.; Sills, D.; Ansari, P.H.; Mack, K.

    1996-04-01

    X-ray absorption spectroscopy (XAS) measurements have been used to probe the electronic structure of ion-beam-mixed (IBM) Pd-Ag thin films with bulk alloys being studied for comparison. Pd {ital L}{sub 3} and Ag {ital L}{sub 3} absorption edges for pure Pd, Ag, and Pd{sub 1{minus}{ital x}}Ag{sub {ital x}} alloys are discussed. Structural information from both x-ray diffraction and the XAS fine structure oscillations are discussed. The observed decrease of the white-line feature strength, at the Pd {ital L}{sub 3} edge, indicates that the local density of unoccupied Pd 4{ital d} states declines upon alloying with Ag in a manner similar to that observed in previous bulk studies. However, while the Pd {ital d}-hole count decreases monotonically for bulk alloys, in the IBM alloys it saturates at higher levels in the Ag-rich materials. This disparity is interpreted on the basis of a modified charge transfer due to structural differences in the IBM alloys. The Ag {ital L}{sub 3} near-edge region is largely unchanged in these alloys, indicating that the charge transferred away from the Ag site is dominantly of {ital non}-{ital d} type. Our experimental results are discussed in the context of recent electronic structure calculations and of previous work on this alloy system. {copyright} {ital 1996 The American Physical Society.}

  11. Plasmonic Ag@oxide nanoprisms for enhanced performance of organic solar cells.

    PubMed

    Du, Peng; Jing, Pengtao; Li, Di; Cao, Yinghui; Liu, Zhenyu; Sun, Zaicheng

    2015-05-01

    Localized surface plasmon resonance (LSPR), light scattering, and lowering the series resistance of noble metal nanoparticles (NPs) provide positive effect on the performance of photovoltaic device. However, the exciton recombination on the noble metal NPs accompanying above influences will deteriorate the performance of device. In this report, surface-modified Ag@oxide (TiO2 or SiO2 ) nanoprisms with 1-2 nm shell thickness are developed. The thin film composed of P3HT/Ag@oxides and P3HT:PCBM/Ag@oxides is investigated by absorption, photoluminescence (PL), and transient absorption spectroscopy. The results show a significant absorption, PL enhancement, and long-lived photogenerated polaron in the P3HT/Ag@TiO2 film, indicating the increase of photogenerated exciton population by LSPR of Ag nanoprisms. In the case of P3HT/Ag nanoprisms, partial PL quench and relatively short-lived photogenerated polaron are observed. That indicates that the oxides layer can effectively avoid the exciton recombination. When the Ag@oxide nanoprisms are introduced into the active layer of P3HT:PCBM photovoltaic devices, about 31% of power conversion efficiency enhancement is obtained relative to the reference cell. All these results indicate that Ag@oxides can enhance the performance of the cell, at the same time the ultrathin oxide shell prevents from the exciton recombination.

  12. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  13. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule ``as run``; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  14. Comparative Photoemission Study of Actinide (Am, Pu, Np and U) Metals, Nitrides, and Hydrides

    SciTech Connect

    Gouder, Thomas; Seibert, Alice; Rebizant, Jean; Huber, Frank; Havela, Ladislav

    2007-07-01

    Core-level and valence-band spectra of Pu and the other early actinide compounds show remarkable systematics, which can be understood in the framework of final state screening. We compare the early actinide (U, Np, Pu and Am) metals, nitrides and hydrides and a few other specific compounds (PuSe, PuS, PuCx, PuSix) prepared as thin films by sputter deposition. In choosing these systems, we combine inherent 5f band narrowing, due to 5f orbital contraction throughout the actinide series, with variations of the chemical environment in the compounds. Goal of this work was to learn more on the electronic structure of the early actinide systems and to achieve the correct interpretation of their photoemission spectra. The highly correlated nature of the 5f states in systems, which are on the verge to localization, makes this a challenging task, because of the peculiar interplay between ground state DOS and final-state effects. Their influence can be estimated by doing systematic studies on systems with different (5f) bandwidths. We conclude on the basis of such systematic experiments that final-state effects due to strong e-e correlations in narrow 5f-band systems lead to multiplet like structures, analogous to those observed in the case of systems with localized electron states. Such observations in essentially band-like 5f-systems was first surprising, but the astonishing similarity of photoemission spectra of very different chemical systems (e.g. PuSe, Pu{sub 2}C{sub 3}..) points to a common origin, relating them to atomic features rather than material dependent density of states (DOS) features. (authors)

  15. Rethinking Stability of Silver Sulfide Nanoparticles (Ag2S-NPs) in the Aquatic Environment: Photoinduced Transformation of Ag2S-NPs in the Presence of Fe(III).

    PubMed

    Li, Lingxiangyu; Wang, Yawei; Liu, Qian; Jiang, Guibin

    2016-01-01

    The stability of engineered nanomaterials in a natural aquatic environment has drawn much attention over the past few years. Silver sulfide nanoparticles (Ag2S-NPs) are generally assumed to be stable in a natural environment as a result of their physicochemical property; however, it may vary depending upon environmental conditions. Here, we investigated whether and how the environmentally relevant factors including light irradiation, solution pH, inorganic salts, dissolved organic matter (DOM), and dissolved oxygen (DO) individually and in combination influenced the stability of Ag2S-NPs in an aquatic environment. We presented for the first time that transformation of Ag2S-NPs can indeed occur in the aqueous system with an environmentally relevant concentration of Fe(3+) under simulated solar irradiation and natural sunlight within a short time (96 h), along with significant changes in morphology and dissolution. The photoinduced transformation of Ag2S-NPs in the presence of Fe(3+) can be dramatically influenced by solution pH, Ca(2+)/Na(+), Cl(-)/SO4(2-), DOM, and DO. Moreover, Ag2S-NP dissolution increased within 28 h, followed rapid decline in the next 68 h, which may be a result of the reconstitution of small Ag2S-NPs. Taken together, this work is of importance to comprehensively evaluate the stability of Ag2S-NPs in an aquatic environment, improving our understanding of their potential risks to human and environmental health.

  16. TANK 40 FINAL SB5 CHEMICAL CHARACTERIZATION RESULTS PRIOR TO NP ADDITION

    SciTech Connect

    Bannochie, C.; Click, D.

    2010-01-06

    A sample of Sludge Batch 5 (SB5) was pulled from Tank 40 in order to obtain radionuclide inventory analyses necessary for compliance with the Waste Acceptance Product Specifications (WAPS). This sample was also analyzed for chemical composition including noble metals. Prior to radionuclide inventory analyses, a final sample of the H-canyon Np stream will be added to bound the Np addition anticipated for Tank 40. These analyses along with the WAPS radionuclide analyses will help define the composition of the sludge in Tank 40 that is currently being fed to DWPF as SB5. At the Savannah River National Laboratory (SRNL) the 3-L Tank 40 SB5 sample was transferred from the shipping container into a 4-L high density polyethylene vessel and solids allowed to settle overnight. Supernate was then siphoned off and circulated through the shipping container to complete the transfer of the sample. Following thorough mixing of the 3-L sample, a 239 g sub-sample was removed. This sub-sample was then utilized for all subsequent analytical samples. Eight separate aliquots of the slurry were digested, four with HNO{sub 3}/HCl (aqua regia) in sealed Teflon{reg_sign} vessels and four in Na{sub 2}O{sub 2} (alkali or peroxide fusion) using Zr crucibles. Due to the use of Zr crucibles and Na in the peroxide fusions, Na and Zr cannot be determined from this preparation. Additionally, other alkali metals, such as Li and K that may be contaminants in the Na{sub 2}O{sub 2} are not determined from this preparation. Three Analytical Reference Glass - 14 (ARG-1) standards were digested along with a blank for each preparation. The ARG-1 glass allows for an assessment of the completeness of each digestion. Each aqua regia digestion and blank was diluted to 1:100 mL with deionized water and submitted to Analytical Development (AD) for inductively coupled plasma - atomic emission spectroscopy (ICPAES) analysis, inductively coupled plasma - mass spectrometry (ICP-MS) analysis of masses 81-209 and 230

  17. TANK 40 FINAL SB5 CHEMICAL CHARACTERIZATION RESULTS PRIOR TO NP ADDITION

    SciTech Connect

    Bannochie, C; Damon Click, D

    2009-02-26

    A sample of Sludge Batch 5 (SB5) was pulled from Tank 40 in order to obtain radionuclide inventory analyses necessary for compliance with the Waste Acceptance Product Specifications (WAPS). This sample was also analyzed for chemical composition including noble metals. Prior to radionuclide inventory analyses, a final sample of the H-canyon Np stream will be added to bound the Np addition anticipated for Tank 40. These analyses along with the WAPS radionuclide analyses will help define the composition of the sludge in Tank 40 that is currently being fed to DWPF as SB5. At the Savannah River National Laboratory (SRNL) the 3-L Tank 40 SB5 sample was transferred from the shipping container into a 4-L high density polyethylene vessel and solids allowed to settle overnight. Supernate was then siphoned off and circulated through the shipping container to complete the transfer of the sample. Following thorough mixing of the 3-L sample, a 239 g sub-sample was removed. This sub-sample was then utilized for all subsequent analytical samples. Eight separate aliquots of the slurry were digested, four with HNO{sub 3}/HCl (aqua regia) in sealed Teflon{reg_sign} vessels and four in Na{sub 2}O{sub 2} (alkali or peroxide fusion) using Zr crucibles. Due to the use of Zr crucibles and Na in the peroxide fusions, Na and Zr cannot be determined from this preparation. Additionally, other alkali metals, such as Li and K that may be contaminants in the Na{sub 2}O{sub 2} are not determined from this preparation. Three Analytical Reference Glass-1 (ARG-1) standards were digested along with a blank for each preparation. The ARG-1 glass allows for an assessment of the completeness of each digestion. Each aqua regia digestion and blank was diluted to 1:100 mL with deionized water and submitted to Analytical Development (AD) for inductively coupled plasma--atomic emission spectroscopy (ICPAES) analysis, inductively coupled plasma--mass spectrometry (ICP-MS) analysis of masses 81-209 and 230

  18. Calibration factors for the SNOOPY NP-100 neutron dosimeter

    NASA Astrophysics Data System (ADS)

    Moscu, D. F.; McNeill, F. E.; Chase, J.

    2007-10-01

    Within CANDU nuclear power facilities, only a small fraction of workers are exposed to neutron radiation. For these individuals, roughly 4.5% of the total radiation equivalent dose is the result of exposure to neutrons. When this figure is considered across all workers receiving external exposure of any kind, only 0.25% of the total radiation equivalent dose is the result of exposure to neutrons. At many facilities, the NP-100 neutron dosimeter, manufactured by Canberra Industries Incorporated, is employed in both direct and indirect dosimetry methods. Also known as "SNOOPY", these detectors undergo calibration, which results in a calibration factor relating the neutron count rate to the ambient dose equivalent rate, using a standard Am-Be neutron source. Using measurements presented in a technical note, readings from the dosimeter for six different neutron fields in six source-detector orientations were used, to determine a calibration factor for each of these sources. The calibration factor depends on the neutron energy spectrum and the radiation weighting factor to link neutron fluence to equivalent dose. Although the neutron energy spectra measured in the CANDU workplace are quite different than that of the Am-Be calibration source, the calibration factor remains constant - within acceptable limits - regardless of the neutron source used in the calibration; for the specified calibration orientation and current radiation weighting factors. However, changing the value of the radiation weighting factors would result in changes to the calibration factor. In the event of changes to the radiation weighting factors, it will be necessary to assess whether a change to the calibration process or resulting calibration factor is warranted.

  19. Metallic influence on the atomic structure and optical activity of ligand-protected nanoparticles: a comparison between Ag and Au.

    PubMed

    Hidalgo, Francisco; Noguez, Cecilia; Olvera de la Cruz, Monica

    2014-03-21

    Using time-perturbed density functional theory the optical activity of metal-thiolate compounds formed by highly symmetric Ag and Au nanoparticles (NPs) and a methyl-thiol molecule is studied after performing atomic optimizations and electronic calculations upon adsorption. Many different sites and orientations of the adsorbed molecule on icosahedral Ag and Au NPs of 55 atoms are considered. Upon molecular adsorption atomic distortions on Au NPs are induced while not on Ag, which causes higher molecular adsorption energies in Au than in Ag. Structural distortions and the specific molecular adsorption site and orientation result in chiral metal-thiolate NPs. Ag and Au compounds with similar chirality, according to Hausdorff chirality measurements, show different optical activity signatures, where circular dichroism spectra of Au NPs are more intense. These dissimilarities are attributed in part to the differences in the electronic density of states, which are a consequence of relativistic effects and the atomic distortion. It is concluded that the optical activity of Ag and Au compounds is due to different mechanisms, while in Au it is mainly due to the atomic distortion of the metallic NPs induced after molecular adsorption, in Ag it is defined by the adsorption site and molecular orientation with respect to the NP symmetry.

  20. Enhancement of NO2 gas detection in hybrid silver nanoparticles-phthalocyanine thin films

    NASA Astrophysics Data System (ADS)

    Zasedatelev, A. V.; Krichevsky, D. M.; Zelenskiy, Yu M.; Tolbin, A. Yu; Krasovskii, V. I.; Karpo, A. B.; Tomilova, L. G.

    2016-08-01

    Phthalocyanine-functionalized plasmonic sensing systems are typically based on Kretschmann configuration. Such scheme of detection utilizes spectral or angular modulation of reflected light, which is induced by surface plasmon's excitation in the metal film on prism. Phthalocyanine's layer plays a role of analyte adsorber. In present paper we offer another approach to phthalocyanine-plasmonic sensing, where both local surface plasmon resonance and optical absorption of phthalocyanines are simultaneously detected. Hybrid Ag nanoparticles (AgNps) - low symmetrical A3B zinc phthalocyanine (ZnPc) thin films were prepared, and their NO2 gas sensitive properties were examined. Since the plasmon resonance of AgNps was properly tuned to charge-transfer band of ZnPc-NO2 complex, we found out more than two-fold increase of the optical response to NO2 exposure in AgNps-ZnPc thin films compared to ZnPc films without AgNps.

  1. Pulsed laser deposition of Mg-Al layered double hydroxide with Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Matei, A.; Birjega, R.; Vlad, A.; Luculescu, C.; Epurescu, G.; Stokker-Cheregi, F.; Dinescu, M.; Zavoianu, R.; Pavel, O. D.

    2013-03-01

    Powdered layered double hydroxides (LDHs)—also known as hydrotalcite-like (HT)—compounds have been widely studied due to their applications as catalysts, anionic exchangers or host materials for inorganic or organic molecules. Assembling thin films of nano-sized LDHs onto flat solid substrates is an expanding area of research, with promising applications as sensors, corrosion-resistant coatings, components in optical and magnetic devices. The exploitation of LDHs as vehicles to carry dispersed metal nanoparticles onto a substrate is a new approach to obtain composite thin films with prospects for biomedical and optical applications. We report the deposition of thin films of Ag nanoparticles embedded in a Mg-Al layered double hydroxide matrix by pulsed laser deposition (PLD). The Ag-LDH powder was prepared by co-precipitation at supersaturation and pH = 10 using aqueous solutions of Mg and Al nitrates, Na hydroxide and carbonate, and AgNO3, having atomic ratios of Mg/Al = 3 and Ag/Al = 0.55. The target to be used in laser ablation experiments was a dry pressed pellet obtained from the prepared Ag-LDH powder. Three different wavelengths of a Nd:YAG laser (266, 532 and 1064 nm) working at a repetition rate of 10 Hz were used. X-Ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and secondary ions mass spectrometry (SIMS) were used to investigate the structure, surface morphology and composition of the deposited films.

  2. Thin Film?

    NASA Astrophysics Data System (ADS)

    Kariper, İ. Afşin

    2014-09-01

    This study focuses on the critical surface tension of lead sulfite (PbSO3) crystalline thin film produced with chemical bath deposition on substrates (commercial glass).The PbSO3 thin films were deposited at room temperature at different deposition times. The structural properties of the films were defined and examined according to X-ray diffraction (XRD) and the XRD results such as dislocation density, average grain size, and no. of crystallites per unit area. Atomic force microscopy was used to measure the film thickness and the surface properties. The critical surface tension of the PbSO3 thin films was measured with an optical tensiometer instrument and calculated using the Zisman method. The results indicated that the critical surface tension of films changed in accordance with the average grain size and film thickness. The film thickness increased with deposition time and was inversely correlated with surface tension. The average grain size increased according to deposition time and was inversely correlated with surface tension.

  3. Ag@SiO2 core-shell nanoparticles on silicon nanowire arrays as ultrasensitive and ultrastable substrates for surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Zhang, Chang Xing; Su, Lei; Chan, Yu Fei; Wu, Zheng Long; Zhao, Yong Mei; Xu, Hai Jun; Sun, Xiao Ming

    2013-08-01

    Ag nanoparticles (NPs) coated with silica nanolayers were decorated onto a large-scale and uniform silicon nanowire array (SiNWA) by simple chemical etching and metal reduction processes. The three-dimensional Ag/SiNWAs thus formed are employed as a substrate for surface-enhanced Raman scattering (SERS), and a detection limit for rhodamine 6G as low as 10-16 M and a Raman enhancement factor as large as 1014 were obtained. Simulation results show that two kinds of inter-Ag-NP nanogaps in three-dimensional geometry create a huge number of SERS ‘hot spots’ where electromagnetic fields are substantially amplified, contributing to the higher SERS sensitivity and lower detection limit. The excellent SERS stability of Ag/SiNWAs is attributed to the presence of the SiO2 nanolayer around Ag NPs that prevented the Ag NP surface from being oxidized. The calibration of the Raman peak intensities of rhodamine 6G and thiram allowed their quantitative detection. Our finding is a significant advance in developing SERS substrates for the fast and quantitative detection of trace organic molecules.

  4. Particle-Film Plasmons on Periodic Silver Film over Nanosphere (AgFON): A Hybrid Plasmonic Nanoarchitecture for Surface-Enhanced Raman Spectroscopy.

    PubMed

    Lee, Jiwon; Zhang, Qianpeng; Park, Seungyoung; Choe, Ayoung; Fan, Zhiyong; Ko, Hyunhyub

    2016-01-13

    Plasmonic systems based on particle-film plasmonic couplings have recently attracted great attention because of the significantly enhanced electric field at the particle-film gaps. Here, we introduce a hybrid plasmonic architecture utilizing combined plasmonic effects of particle-film gap plasmons and silver film over nanosphere (AgFON) substrates. When gold nanoparticles (AuNPs) are assembled on AgFON substrates with controllable particle-film gap distances, the AuNP-AgFON system supports multiple plasmonic couplings from interparticle, particle-film, and crevice gaps, resulting in a huge surface-enhanced Raman spectroscopy (SERS) effect. We show that the periodicity of AgFON substrates and the particle-film gaps greatly affects the surface plasmon resonances, and thus, the SERS effects due to the interplay between multiple plasmonic couplings. The optimally designed AuNP-AgFON substrate shows a SERS enhancement of 233 times compared to the bare AgFON substrate. The ultrasensitive SERS sensing capability is also demonstrated by detecting glutathione, a neurochemical molecule that is an important antioxidant, down to the 10 pM level.

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

    NASA Astrophysics Data System (ADS)

    Rebelo, Rita; Manninen, N. K.; Fialho, Luísa; Henriques, Mariana; Carvalho, Sandra

    2016-05-01

    Ag and AgxO 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 AgxO thin film showed both metallic Ag and Agsbnd O bonds, which crystalize in fcc-Ag and silver oxide phases. The SEM results revealed that Ag thin film formed a continuous layer, while AgxO 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 AgxO 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 AgxO coating, which presented antibacterial properties against the studied bacteria. The presence of silver oxide phase along with the development of different morphology was pointed as the main factors in the origin of the antibacterial effect found in AgxO thin film. The present study demonstrated that AgxO coating presented antibacterial behavior and its application in cardiovascular stents is promising.

  6. Effect of adatom surface diffusivity on microstructure and intrinsic stress evolutions during Ag film growth

    NASA Astrophysics Data System (ADS)

    Flötotto, D.; Wang, Z. M.; Jeurgens, L. P. H.; Bischoff, E.; Mittemeijer, E. J.

    2012-08-01

    The effect of the adatom surface diffusivity on the evolution of the microstructure and the intrinsic stress of thin metal films was investigated for the case of growth of polycrystalline Ag films on amorphous SiO2 (a-SiO2) and amorphous Ge (a-Ge) substrates, with high and low Ag adatom surface diffusivity, respectively. The surface diffusivity of the deposited Ag adatoms on the a-Ge substrate is suppressed also after coalescence of Ag islands due to the continuous (re)segregation of Ge at the surface of the growing film as evidenced by in-situ XPS. An assessment could be made of the role of adatom surface diffusivity on the microstructural development and the intrinsic stress evolution during film growth. As demonstrated by ex-situ TEM and ex-situ XRD, the Ag films grown on the a-SiO2 and a-Ge substrates possess strikingly different microstructures in terms of grain shape, grain size, and crystallographic texture. Nevertheless, the real-time in-situ stress measurements revealed a compressive → tensile → compressive stress evolution for the developing Ag films on both types of substrates, however on different time scales and with stress-component values of largely different magnitudes. It was concluded that (i) the microstructural development of metallic thin films is predominated by the surface diffusivity of the adatoms and (ii) the intrinsic stress evolution is largely controlled by the developing microstructure and the grain-boundary diffusivity.

  7. Thermoelectric Properties of Hybrid Thin Films of PEDOT-PSS and Silver Nanowires

    NASA Astrophysics Data System (ADS)

    Yoshida, Akihito; Toshima, Naoki

    2016-06-01

    We report the thermoelectric (TE) properties of organic-inorganic hybrid thin films composed of conductive polymer, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS), and inorganic silver nanowire (AgNW). Two kinds of AgNW with different wire length, 3 μm and 27 μm, were used in this study. The AgNW/PEDOT-PSS hybrid films showed an increase in electrical conductivity ( σ) with increase in AgNW concentration. The maximum value of σ obtained in this system was ca. 10,000 S cm-1. The films containing long AgNWs (L-AgNWs) showed higher σ relative to short AgNWs (S-AgNWs) at given concentration, which results from the fact that longer nanowires can easily form a percolated structure. The formation of a percolated structure was confirmed by scanning electron microscopy (SEM) observation. On the other hand, the Seebeck coefficient ( S) of the hybrid films showed the opposite dependence on AgNW concentration. This decrease in S with increasing AgNW concentration is probably because of increase in carrier number due to the AgNWs. These results suggest that the presented organic-inorganic hybrid system is one example where the electrical conductivity and TE properties can be tuned by use of a nanocomposite.

  8. Hollow Au/Ag nanostars displaying broad plasmonic resonance and high surface-enhanced Raman sensitivity.

    PubMed

    Garcia-Leis, Adianez; Torreggiani, Armida; Garcia-Ramos, Jose Vicente; Sanchez-Cortes, Santiago

    2015-08-28

    Bimetallic Au/Ag hollow nanostar (HNS) nanoparticles with different morphologies were prepared in this work. These nanoplatforms were obtained by changing the experimental conditions (concentration of silver and chemical reductors, hydroxylamine and citrate) and by using Ag nanostars as template nanoparticles (NPs) through galvanic replacement. The goal of this research was to create bimetallic Au/Ag star-shaped nanoparticles with advanced properties displaying a broader plasmonic resonance, a cleaner exposed surface, and a high concentration of electromagnetic hot spots on the surface provided by the special morphology of nanostars. The size, shape, and composition of Ag as well as their optical properties were studied by extinction spectroscopy, hyperspectral dark field microscopy, transmission and scanning electron microscopy (TEM and SEM), and energy dispersive X-ray spectroscopy (EDX). Finally, the surface-enhanced Raman scattering (SERS) activity of these HNS was investigated by using thioflavin T, a biomarker of the β-amyloid fibril formation, responsible for Alzheimer's disease. Lucigenin, a molecule displaying different SERS activities on Au and Ag, was also used to explore the presence of these metals on the NP surface. Thus, a relationship between the morphology, plasmon resonance and SERS activity of these new NPs was made.

  9. SERS-barcoded colloidal gold NP assemblies as imaging agents for use in biodiagnostics

    NASA Astrophysics Data System (ADS)

    Dey, Priyanka; Olds, William; Blakey, Idriss; Thurecht, Kristofer J.; Izake, Emad L.; Fredericks, Peter M.

    2014-03-01

    There is a growing need for new biodiagnostics that combine high throughput with enhanced spatial resolution and sensitivity. Gold nanoparticle (NP) assemblies with sub-10 nm particle spacing have the benefits of improving detection sensitivity via Surface enhanced Raman scattering (SERS) and being of potential use in biomedicine due to their colloidal stability. A promising and versatile approach to form solution-stable NP assemblies involves the use of multi-branched molecular linkers which allows tailoring of the assembly size, hot-spot density and interparticle distance. We have shown that linkers with multiple anchoring end-groups can be successfully employed as a linker to assemble gold NPs into dimers, linear NP chains and clustered NP assemblies. These NP assemblies with diameters of 30-120 nm are stable in solution and perform better as SERS substrates compared with single gold NPs, due to an increased hot-spot density. Thus, tailored gold NP assemblies are potential candidates for use as biomedical imaging agents. We observed that the hot-spot density and in-turn the SERS enhancement is a function of the linker polymer concentration and polymer architecture. New deep Raman techniques like Spatially Offset Raman Spectroscopy (SORS) have emerged that allow detection from beneath diffusely scattering opaque materials, including biological media such as animal tissue. We have been able to demonstrate that the gold NP assemblies could be detected from within both proteinaceous and high lipid containing animal tissue by employing a SORS technique with a backscattered geometry.

  10. Sorption behavior of nonylphenol (NP) on sewage-irrigated soil: kinetic and thermodynamic studies.

    PubMed

    Liao, Xiaoping; Zhang, Caixiang; Yao, Linlin; Li, Jiale; Liu, Min; Xu, Liang; Evalde, Mulindankaka

    2014-03-01

    The reuse of wastewater for irrigation of agricultural land is a well established resources management practice but has the disadvantage of inputting various forms of contaminants into the terrestrial environment including nonylphenol (NP), a well known endocrine disrupting substance. To elucidate the environmental fate and transport of NP, the sorption behavior on sewage-irrigated soil was studied by batch experiment. It was found that sorption processes of NP on different sorbents (soil, humic acid (HA) and silica) could be expressed well using two compartment pseudo first-order model, where both surface and intra-particle diffusion were probable rate-controlling processes. Linear model could better express the sorption of NP on soil, black carbon (BC) and mineral (e.g., SiO2) except HA than Freundlich model. The large value of distribution coefficients of normalized organic carbon (Koc) on soils indicated that NP was limited to migrate to deep soil. The higher desorption partition coefficient of NP on soil showed enhanced hysteresis. According to the experimental data, the calculated thermodynamic parameters implied that the sorption reaction on sewage-irrigation was spontaneous, exothermic and entropy decreasing process. The amount of soil organic matter (SOM) dominated the sorption capacity, whereas the sorption behavior of NP on soil showed no significant correlation with ionic strength.

  11. Facile Routes to Th(IV), U(IV), and Np(IV) Phosphites and Phosphates

    SciTech Connect

    Villa, Eric M.; Wang, Shuao; Alekseev, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.

    2011-08-05

    Three actinide(IV) phosphites and a NpIV phosphate, AnIV(HPO₃)₂(H₂O)₂ (An = Th, U, Np) and Cs[Np(H1.5PO₄)(PO₄)]₂, respectively, were synthesized using mild hydrothermal conditions. The first three phases are isotypic and were obtained using similar reaction conditions. Cs[Np(H1.5PO₄)(PO₄)]₂ was synthesized using an analogous method to that of Np(HPO₃)₂(H₂O)₂. However, this fourth phase is quite different in comparison to the other phases in both composition and structure. The structure of Cs[Np(H1.5PO₄)(PO₄)]₂ is constructed from double layers of neptunium(IV) phosphate with caesium cations in the interlayer region. In contrast, An(HPO₃)₂(H₂O)₂ (An = Th, U, Np) form dense 3D networks. The actinide contraction is detected in variety of metrics obtained from single-crystal X-ray diffraction data. Changes in the oxidation state of the neptunium starting materials yield different products.

  12. The AGS-Booster lattice

    SciTech Connect

    Lee, Y.Y.; Barton, D.S.; Claus, J.; Cottingham, J.G.; Courant, E.D.; Danby, G.T.; Dell, G.F.; Forsyth, E.B.; Gupta, R.C.; Kats, J.

    1987-01-01

    The AGS Booster has three objectives. They are to increase the space charge limit of the AGS, to increase the intensity of the polarized proton beam by accumulating many linac pulses (since the intensity is limited by the polarized ion source), and to reaccelerate heavy ions from the BNL Tandem Van de Graaff before injection into the AGS. The machine is capable of accelerating protons at 7.5 Hertz from 200 MeV to 1.5 GeV or to lower final energies at faster repetition rates. The machine will also be able to accelerate heavy ions from as low as 1 MeV/nucleon to a magnetic rigidity as high as 17.6 Tesla-meters with a one second repetition rate. As an accumulator for polarized protons, the Booster should be able to store the protons at 200 MeV for several seconds. We expect that the Booster will increase the AGS proton intensity by a factor of four, polarized proton intensity by a factor of twenty to thirty, and will also enable the AGS to accelerate all species of heavy ions (at present the AGS heavy ion program is limited to the elements lighter than sulfur because it can only accelerate fully stripped ions). The construction project started in FY 1985 and is expected to be completed in 1989. The purpose of this paper is to provide a future reference for the AGS Booster lattice.

  13. X-ray photoelectron spectra structure and chemical bond nature in NpO2

    NASA Astrophysics Data System (ADS)

    Teterin, Yu. A.; Teterin, A. Yu.; Ivanov, K. E.; Ryzhkov, M. V.; Maslakov, K. I.; Kalmykov, St. N.; Petrov, V. G.; Enina, D. A.

    2014-01-01

    Quantitative analysis was done of the x-ray photoelectron spectra structure in the binding energy (BE) range of 0 to ˜35 eV for neptunium dioxide (NpO2) valence electrons. The BEs and structure of the core electronic shells (˜35-1250 eV) as well as the relativistic discrete variation calculation results for the finite fragment of the NpO2 lattice and the data of other authors were taken into account. The experimental data show that the many-body effects and the multiplet splitting contribute to the spectral structure much less than the effects of formation of the outer (0-˜15 eV) and the inner (˜15-˜35 eV) valence molecular orbitals (OVMO and IVMO, respectively). The filled Np 5f electronic states were shown to form in the NpO2 valence band. The Np 6p electrons participate in formation of both the IVMO and the OVMO (bands). The filled Np 6p3/2 and the O 2s electronic shells were found to take the maximum part in the IVMO formation. The MO composition and the sequence order in the BE range 0-˜35 eV in NpO2 were established. The experimental and theoretical data allowed a quantitative MO scheme for NpO2, which is fundamental for both understanding the chemical bond nature in neptunium dioxide and the interpretation of other x-ray spectra of NpO2.

  14. Precision Photothermal Annealing of Nanoporous Gold Thin Films for the Microfabrication of a Single-chip Material Libraries

    SciTech Connect

    Harris, C. D.; Shen, N.; Rubenchik, A.; Demos, S. G.; Matthews, M. J.

    2015-06-30

    Single-chip material libraries of thin films of nanostructured materials are a promising approach for high throughput studies of structure-property relationship in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material of specific interest in both these fields. One attractive property of np-Au is its self-similar coarsening behavior by thermally induced surface diffusion. However, traditional heat application techniques for the modification of np-Au are bulk processes that cannot be used to generate a library of different pore sizes on a single chip. Laser micromachining offers an attractive solution to this problem by providing a means to apply energy with high spatial and temporal resolution. In the present study we use finite element multiphysics simulations to predict the effects of laser mode (continuous-wave vs. pulsed) and supporting substrate thermal conductivity on the local np-Au film temperatures during photothermal annealing and subsequently investigate the mechanisms by which the np-Au network is coarsening. Our simulations predict that continuous-wave mode laser irradiation on a silicon supporting substrate supports the widest range of morphologies that can be created through the photothermal annealing of thin film np-Au. Using this result we successfully fabricate a single-chip material library consisting of 81 np-Au samples of 9 different morphologies for use in increased throughput material interaction studies.

  15. Laser-nanostructured Ag films as substrates for surface-enhanced Raman spectroscopy

    SciTech Connect

    Henley, S.J.; Carey, J.D.; Silva, S.R.P.

    2006-02-20

    Pulsed-laser (248 nm) irradiation of Ag thin films was employed to produce nanostructured Ag/SiO{sub 2} substrates. By tailoring the laser fluence, it was possible to controllably adjust the mean diameter of the resultant near-spherical Ag droplets. Thin films of tetrahedral amorphous carbon (ta-C) were subsequently deposited onto the nanostructured substrates. Visible Raman measurements were performed on the ta-C films, where it was observed that the intensity of the Raman signal was increased by nearly two orders of magnitude, when compared with ta-C films grown on nonstructured substrates. The use of laser annealing as a method of preparing substrates, at low macroscopic temperatures, for surface-enhanced Raman spectroscopy on subnanometer-thick films is discussed.

  16. Water dissociation on Mn(1×1)/Ag(100)

    DOE PAGES

    Arble, Chris; Tong, Xiao; Giordano, Livia; Ferrari, Anna Maria; Newberg, John T.

    2016-08-19

    In this work we utilize experimental and simulation techniques to examine the molecular level interaction of water with a MnO(1×1) thin film deposited onto Ag(100). The formation of MnO(1×1)/Ag(100) was characterized by low energy electron diffraction and scanning tunneling microscopy. Density functional theory (DFT) shows MnO(1×1) is thermodynamically more stable than MnO(2×1) by –0.4 eV per MnO. Upon exposure to 2.5 Torr water vapor at room temperature, X-ray photoemission spectroscopy results show extensive surface hydroxylation attributed to reactivity at MnO(1×1) terrace sites. DFT calculations of a water monomer on MnO(1×1)/Ag(100) show the dissociated form is energetically more favorable than molecularmore » adsorption, with a hydroxylation activation barrier 0.4 eV per H2O. Lastly, these results are discussed and contrasted with previous studies of MgO/Ag(100) which show a stark difference in behavior for water dissociation.« less

  17. Nanostructured Ag(4)O(4) films with enhanced antibacterial activity.

    PubMed

    Dellasega, D; Facibeni, A; Di Fonzo, F; Bogana, M; Polissi, A; Conti, C; Ducati, C; Casari, C S; Li Bassi, A; Bottani, C E

    2008-11-26

    Ag(4)O(4) (i.e. silver(I)-silver(III) oxide) thin films with tailored structure and morphology at the nanoscale have been grown by reactive pulsed laser deposition (PLD) in an oxygen-containing atmosphere and they are shown to exhibit a very strong antibacterial activity towards Gram-negative bacteria (E. coli) and to completely inhibit the growth of Gram-positive bacteria (S. aureus). The formation of this particular high-valence silver oxide is explained in terms of the reactions occurring during the expansion of the ablated species in the reactive atmosphere, leading to the formation of low-stability Ag-O dimers and atomic oxygen, providing reactive species at the substrate where the film grows. PLD is shown to allow control of the structure (i.e. crystallinity and grain size) and of the morphology of the films, from compact and columnar to foam-like, thus allowing the deposition of nanocrystalline films with increased porosity and surface area. The antibacterial action towards E. coli is demonstrated and is shown to be superior to that of nanostructured Ag-based medical products. This can be related to the release of Ag ions with high oxidation number, which are known to be very reactive towards bacteria, and to the peculiar morphology at the nanoscale resulting in a large effective surface area.

  18. Robust Au-Ag-Au bimetallic atom-scale junctions fabricated by self-limited Ag electrodeposition at Au nanogaps.

    PubMed

    Hwang, Tai-Wei; Bohn, Paul W

    2011-10-25

    Atom-scale junctions (ASJs) exhibit quantum conductance behavior and have potential both for fundamental studies of adsorbate-mediated conductance in mesoscopic conductors and as chemical sensors. Electrochemically fabricated ASJs, in particular, show the stability needed for molecular detection applications. However, achieving physically robust ASJs at high yield is a challenge because it is difficult to control the direction and kinetics of metal deposition. In this work, a novel electrochemical approach is reported, in which Au-Ag-Au bimetallic ASJs are reproducibly fabricated from an initially prepared Au nanogap by sequential overgrowth and self-limited thinning. Applying a potential across specially prepared Au nanoelectrodes in the presence of aqueous Ag(I) leads to preferential galvanic reactions resulting in the deposition of Ag and the formation of an atom-scale junction between the electrodes. An external resistor is added in series with the ASJ to control self-termination, and adjusting solution chemical potential (concentration) is used to mediate self-thinning of junctions. The result is long-lived, mechanically stable ASJs that, unlike previous constructions, are stable in flowing solution, as well as to changes in solution media. These bimetallic ASJs exhibit a number of behaviors characteristic of quantum structures, including long-lived fractional conductance states, that are interpreted to arise from two or more quantized ASJs in series.

  19. Optical Absorption, Stability and Structure of NpO2+ Complexeswith Dicarboxylic Acids

    SciTech Connect

    Guoxin Tian; Linfeng Rao

    2006-01-04

    Complexation of NpO2+ with oxalic acid (OX),2,2'-oxydiacetic acid (ODA), 2,2'-iminodiacetic acid (IDA) and 2,2'-thiodiacetic acid (TDA), has been studied using spectrophotometry in1 M NaClO4. Both the position and the intensity of the absorption band of NpO2+ at 980 nm are affected by the formation of NpO2+/dicarboxylate complexes, providing useful information on the complexation strength, the coordination mode and the structure of the complexes.

  20. Genotoxicity and molecular response of silver nanoparticle (NP)-based hydrogel

    PubMed Central

    2012-01-01

    Background Since silver-nanoparticles (NPs) possess an antibacterial activity, they were commonly used in medical products and devices, food storage materials, cosmetics, various health care products, and industrial products. Various silver-NP based medical devices are available for clinical uses, such as silver-NP based dressing and silver-NP based hydrogel (silver-NP-hydrogel) for medical applications. Although the previous data have suggested silver-NPs induced toxicity in vivo and in vitro, there is lack information about the mechanisms of biological response and potential toxicity of silver-NP-hydrogel. Methods In this study, the genotoxicity of silver-NP-hydrogel was assayed using cytokinesis-block micronucleus (CBMN). The molecular response was studied using DNA microarray and GO pathway analysis. Results and discussion The results of global gene expression analysis in HeLa cells showed that thousands of genes were up- or down-regulated at 48 h of silver-NP-hydrogel exposure. Further GO pathway analysis suggested that fourteen theoretical activating signaling pathways were attributed to up-regulated genes; and three signal pathways were attributed to down-regulated genes. It was discussed that the cells protect themselves against silver NP-mediated toxicity through up-regulating metallothionein genes and anti-oxidative stress genes. The changes in DNA damage, apoptosis and mitosis pathway were closely related to silver-NP-induced cytotoxicity and chromosome damage. The down-regulation of CDC14A via mitosis pathway might play a role in potential genotoxicity induced by silver-NPs. Conclusions The silver-NP-hydrogel induced micronuclei formation in cellular level and broad spectrum molecular responses in gene expression level. The results of signal pathway analysis suggested that the balances between anti-ROS response and DNA damage, chromosome instability, mitosis inhibition might play important roles in silver-NP induced toxicity. The inflammatory factors

  1. The synthesis and characterization of neptunium hydroxysulfate, Np(OH) 2SO 4

    NASA Astrophysics Data System (ADS)

    Wester, D. W.; Mulak, J.; Banks, R.; Carnall, W. T.

    1982-11-01

    Neptunium (IV) hydroxysulfate, Np(OH) 2SO 4, was synthesized using hydrothermal techniques. The X-ray powder diffraction pattern indicates that the compound is isomorphous with the Th(IV) and U(IV) analogs. Cell constants for the three compounds clearly show the effects of the actinide contraction. Visible and near-ir spectra are consistent with the presence of Np(IV) and are compared to spectra of Np(IV) in acidic solution. The ir spectrum contains bands which are assigned to the hydroxy and sulfate groups.

  2. Single-crystal structures of uranium and neptunium oxychalcogenides (An=U,Np; Q=S,Se).

    SciTech Connect

    Jin, Geng Bang; Raw, Adam D.; Skanthakumar, S; Haire, Richard G.; Soderholm, L; Ibers, James A.

    2010-01-01

    The compoundsUOS,UOSe,NpOS,andNpOSehavebeensynthesizedandtheirstructuresdetermined by meansofsingle-crystalX-raydiffractionmethods.Theresultsprovidemoredetailedcrystallographic information,includingmorepreciseinteratomicdistances,thanearlierdeterminationsfrompowder diffractiondata.TheseisostructuralcompoundsadoptthePbFClstructuretype.Each An atom is surroundedbyfourOandfive Q atomsinadistortedmonocappedsquare-antiprismaticarrangement

  3. Amperometric detection and electrochemical oxidation of aliphatic amines and ammonia on silver-lead oxide thin-film electrodes

    SciTech Connect

    Ge, Jisheng

    1996-01-08

    This thesis comprises three parts: Electrocatalysis of anodic oxygen-transfer reactions: aliphatic amines at mixed Ag-Pb oxide thin-film electrodes; oxidation of ammonia at anodized Ag-Pb eutectic alloy electrodes; and temperature effects on oxidation of ethylamine, alanine, and aquated ammonia.

  4. Core-shell AgSiO2-protoporphyrin IX nanoparticle: Effect of the Ag core on reactive oxygen species generation

    NASA Astrophysics Data System (ADS)

    Lismont, M.; Pá; ez-Martinez, C.; Dreesen, L.

    2015-03-01

    Photodynamic therapy (PDT) for cancer is based on the use of a light sensitive molecule to produce, under specific irradiation, toxic reactive oxygen species (ROS). A way to improve the therapy efficiency is to increase the amount of produced ROS near cancer cells. This aim can be achieved by using a metal enhanced process arising when an optically active molecule is located near a metallic nanoparticle (NP). Here, the coupling effect between silver (Ag) NPs and protoporphyrin IX (PpIX) molecules, a clinically approved photosensitizer, is studied compared first, to PpIX fluorescence yield and second, to ROS production efficiency. By applying a modified Stöber process, PpIX was encapsulated into a silica (SiO2) shell, surrounding a 60 nm sized Ag core. We showed that, compared to SiO2-PpIX NPs, Ag coated SiO2-PpIX NPs dramatically decreased PpIX fluorescence together with singlet oxygen production efficiency. However, after incubation time in the dark, the amount of superoxide anions generated by the Ag doped sample was higher than the control sample one.

  5. Post-growth process for flexible CdS/CdTe thin film solar cells with high specific power.

    PubMed

    Cho, Eunwoo; Kang, Yoonmook; Kim, Donghwan; Kim, Jihyun

    2016-05-16

    We demonstrated a flexible CdS/CdTe thin film solar cell with high specific power of approximately 254 W/kg. A flexible and ultra-light weight CdS/CdTe cell treated with pre-NP etch process exhibited high conversion efficiency of 13.56% in superstrate configuration. Morphological, structural and optical changes of CdS/CdTe thin films were characterized when pre-NP etch step was incorporated to the conventional post-deposition process. Improvement of photovoltaic parameters can be attributed to the removal of the oxide and the formation of Te-rich layer, which benefit the activation process. Pre-NP etched cell maintained their flexibility and performance under the repeated tensile strain of 0.13%. Our method can pave a way for manufacturing flexible CdS/CdTe thin film solar cells with high specific power for mobile and aerospace applications.

  6. Post-growth process for flexible CdS/CdTe thin film solar cells with high specific power.

    PubMed

    Cho, Eunwoo; Kang, Yoonmook; Kim, Donghwan; Kim, Jihyun

    2016-05-16

    We demonstrated a flexible CdS/CdTe thin film solar cell with high specific power of approximately 254 W/kg. A flexible and ultra-light weight CdS/CdTe cell treated with pre-NP etch process exhibited high conversion efficiency of 13.56% in superstrate configuration. Morphological, structural and optical changes of CdS/CdTe thin films were characterized when pre-NP etch step was incorporated to the conventional post-deposition process. Improvement of photovoltaic parameters can be attributed to the removal of the oxide and the formation of Te-rich layer, which benefit the activation process. Pre-NP etched cell maintained their flexibility and performance under the repeated tensile strain of 0.13%. Our method can pave a way for manufacturing flexible CdS/CdTe thin film solar cells with high specific power for mobile and aerospace applications. PMID:27409952

  7. Design guideline of high efficiency crystalline Si thin film solar cell with nanohole array textured surface

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Yu, Hongyu; Li, Junshuai; Wong, Shemein; Sun, Xiao Wei; Wang, Xincai; Zheng, Hongyu

    2011-04-01

    Silicon thin film with a nanohole (NH) array textured surface is systematically studied via simulation for solar energy harvesting and compared with a nanopillar (NP) array textured one. It is found that for the same thickness and optimized structure parameters, the NH array shows superior light trapping capability and thus, higher power conversion efficiency than its NP counterpart. The requirement for efficient cells at the optically optimized NH and NP geometries are studied in terms of minority carrier diffusion length, emitter doping level, and the emitter junction depth after considering the impact of surface recombination velocity. The results provide a practical guideline to design and fabricate high efficiency and cost effective NH textured Si thin film solar cells.

  8. Spin dynamics simulations at AGS

    SciTech Connect

    Huang, H.; MacKay, W.W.; Meot, F.; Roser, T.

    2010-05-23

    To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electromagnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.

  9. Analysis of Np-237 ENDF for the theortical interpretation of critical assembly experiments.

    SciTech Connect

    Mihaila, B.; Chadwick, M. B.; MacFarlane, R. E.; Kawano, T.

    2004-01-01

    We report on the present status of our effort toward an improved Np-237 evaluated nuclear data file (ENDF). The aim here is to bridge the gap between calculated and observed k-eff values, as measured at the Np-U critical assembly at LANL, TA-18. As such, we perform a critical analysis of the existing body of experimental data and recommended evaluations. We are targeting in principal the fission nu-bar and cross section in Np-237, as well as the inelastic scattering which is particularly important since Np-237 is a threshold fissioner. This analysis will be employed in a future sensitivity study of the calculated k-eff with respect to variations of the afore mentioned nuclear data.

  10. Magic wavelengths for the np-ns transitions in alkali-metal atoms

    SciTech Connect

    Arora, Bindiya; Safronova, M. S.; Clark, Charles W.

    2007-11-15

    Extensive calculations of the electric-dipole matrix elements in alkali-metal atoms are conducted using the relativistic all-order method. This approach is a linearized version of the coupled-cluster method, which sums infinite sets of many-body perturbation theory terms. All allowed transitions between the lowest ns, np{sub 1/2}, np{sub 3/2} states and a large number of excited states are considered in these calculations and their accuracy is evaluated. The resulting electric-dipole matrix elements are used for the high-precision calculation of frequency-dependent polarizabilities of the excited states of alkali-metal atoms. We find 'magic' wavelengths in alkali-metal atoms for which the ns and np{sub 1/2} and np{sub 3/2} atomic levels have the same ac Stark shifts, which facilitates state-insensitive optical cooling and trapping.

  11. Microstructural investigation of the oxidation behavior of Cu in Ag-coated Cu films using a focused ion beam transmission electron microscopy technique

    NASA Astrophysics Data System (ADS)

    Kim, Ji Hwan; Lee, Jong-Hyun

    2016-06-01

    With the aim of elucidating a detailed mechanism for the oxidation behavior in submicron Cu particles coated with a thin Ag layer, the dewetting of Ag and the oxidation behavior of Cu in Ag-coated Cu films upon heating were investigated with a focused ion beam transmission electron microscopy technique. A slight dewetting of the Ag layer began at approximately 200 °C and aggregates of Cu2O particles were formed on the Ag layer, indicating that the initial Cu2O phase was formed on the thin Ag layer. Voids were formed in the Cu layer because of Cu atoms diffusing through the thin Ag layer to be oxidized in the upper Cu2O aggregates. After being heated to 250 °C, the Ag layer became more irregular, and in some regions, it disappeared because of intensive dewetting. The number and average size of the voids also increased. At 300 °C, a hollow structure with a Cu2O shell was formed. Pillar-like structures of unoxidized Cu and large voids were found under the Cu2O layer.

  12. Template-Stripped Smooth Ag Nanohole Arrays with Silica Shells for Surface Plasmon Resonance Biosensing

    PubMed Central

    Im, Hyungsoon; Lee, Si Hoon; Wittenberg, Nathan J.; Johnson, Timothy W.; Lindquist, Nathan C.; Nagpal, Prashant; Norris, David J.; Oh, Sang-Hyun

    2011-01-01

    Inexpensive, reproducible and high-throughput fabrication of nanometric apertures in metallic films can benefit many applications in plasmonics, sensing, spectroscopy, lithography and imaging. Here we use template stripping to pattern periodic nanohole arrays in optically thick, smooth Ag films with a silicon template made via nanoimprint lithography. Ag is a low-cost material with good optical properties, but it suffers from poor chemical stability and biocompatibility. However, a thin silica shell encapsulating our template-stripped Ag nanoholes facilitates biosensing applications by protecting the Ag from oxidation as well as providing a robust surface that can be readily modified with a variety of biomolecules using well-established silane chemistry. The thickness of the conformal silica shell can be precisely tuned by atomic layer deposition, and a 15-nm-thick silica shell can effectively prevent fluorophore quenching. The Ag nanohole arrays with silica shells can also be bonded to polydimethylsiloxane (PDMS) microfluidic channels for fluorescence imaging, formation of supported lipid bilayers, and real-time, label-free SPR sensing. Additionally, the smooth surfaces of the template-stripped Ag films enhance refractive index sensitivity compared with as-deposited, rough Ag films. Because nearly centimeter-sized nanohole arrays can be produced inexpensively without using any additional lithography, etching or lift-off, this method can facilitate widespread applications of metallic nanohole arrays for plasmonics and biosensing. PMID:21770414

  13. Preparation of Ag-coated hollow microspheres via electroless plating for application in lightweight microwave absorbers

    NASA Astrophysics Data System (ADS)

    Kim, Wook-Joong; Kim, Sung-Soo

    2015-02-01

    Highly conductive Ag film is coated on hollow silica microspheres via electroless plating for application in lightweight microwave absorbers. The Ag plating is conducted using a two-step process of sensitizing and subsequent plating. The complex permeability and permittivity are determined using the reflection/transmission technique in the composite specimens of Ag-coated microspheres and silicone rubber matrix. Due to the large surface area of the microspheres, a relatively high concentration of AgNO3 is required in order to achieve a uniform Ag coating. In addition, a low concentration of fructose reducing agent is recommended for slow plating. The apparent electrical resistance of the Ag-coated microspheres is strongly dependent on the grain morphology. The thin and uniform Ag-coated particles are characterized by their low electrical resistance, which is as low as 0.1 Ω. The lower the electrical resistance of the microspheres, the higher the dielectric constant of the composite specimens, which results from the enhanced space-charge polarization between the conductive microspheres. The microwave absorbance is enhanced with decreases in the electrical resistance of microspheres due to the increased dielectric loss.

  14. Stable Ag@oxides nanoplates for surface-enhanced Raman spectroscopy of amino acids.

    PubMed

    Du, Peng; Ma, Lan; Cao, Yinghui; Li, Di; Liu, Zhenyu; Wang, Zhenxin; Sun, Zaicheng

    2014-06-11

    Surface enhancement Raman scattering (SERS) is a powerful technique for detecting low-concentration analytes (chemicals and biochemicals). Herein, a high-performance SERS biosensing system has been created by using highly stable Ag@oxides nanoplates as enhancers. The Ag nanoplates were stabilized by coating a uniform ultrathin layer of oxides (SiO2 or TiO2) on the Ag surface through a simple sol-gel route. The thin oxide layer allows the plasmonic property of the original Ag nanoplates to be retained while preventing their contact with external etchants. The oxides provide an excellent platform for binding all kinds of molecules that contain a COOH group in addition to a SH group. We demonstrate that Ag@oxides have high performance with respect to the typical SERS molecule 4-ATP, which contains a typical SH group. Ag@oxides also can be directly employed for the SERS detection of amino acids. The highly stable Ag@oxides nanoplates are believed to hold great promise for fabricating a wide range of biosensors for the detection of many other biomolecules and may also find many interesting opportunities in the fields of biological labeling and imaging.

  15. Molecular release from patterned nanoporous gold thin films

    NASA Astrophysics Data System (ADS)

    Kurtulus, Ozge; Daggumati, Pallavi; Seker, Erkin

    2014-05-01

    Nanostructured materials have shown significant potential for biomedical applications that require high loading capacity and controlled release of drugs. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a promising novel material that benefits from compatibility with microfabrication, tunable pore morphology, electrical conductivity, well-established gold-thiol conjugate chemistry, and biocompatibility. While np-Au's non-biological applications are abundant, its performance in the biomedical field is nascent. In this work, we employ a combination of techniques including nanoporous thin film synthesis, quantitative electron microscopy, fluorospectrometry, and electrochemical surface characterization to study loading capacity and molecular release kinetics as a function of film properties and discuss underlying mechanisms. The sub-micron-thick sputter-coated nanoporous gold films provide small-molecule loading capacities up to 1.12 μg cm-2 and molecular release half-lives between 3.6 hours to 12.8 hours. A systematic set of studies reveals that effective surface area of the np-Au thin films on glass substrates plays the largest role in determining loading capacity. The release kinetics on the other hand depends on a complex interplay of micro- and nano-scale morphological features.Nanostructured materials have shown significant potential for biomedical applications that require high loading capacity and controlled release of drugs. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a promising novel material that benefits from compatibility with microfabrication, tunable pore morphology, electrical conductivity, well-established gold-thiol conjugate chemistry, and biocompatibility. While np-Au's non-biological applications are abundant, its performance in the biomedical field is nascent. In this work, we employ a combination of techniques including nanoporous thin film synthesis, quantitative electron microscopy

  16. Gold nanoparticles supported in zirconia-ceria mesoporous thin films: a highly active reusable heterogeneous nanocatalyst.

    PubMed

    Violi, Ianina L; Zelcer, Andrés; Bruno, Mariano M; Luca, Vittorio; Soler-Illia, Galo J A A

    2015-01-21

    Gold nanoparticles (NP) trapped in the mesopores of mixed zirconia-ceria thin films are prepared in a straightforward and reproducible way. The films exhibit enhanced stability and excellent catalytic activity in nitro-group reduction by borohydride and electrocatalytic activity in CO and ethanol oxidation and oxygen reduction.

  17. 237Np Mössbauer studies on actinide superconductors and related materials

    NASA Astrophysics Data System (ADS)

    Colineau, Eric; Gaczyński, Piotr; Griveau, Jean-Christophe; Eloirdi, Rachel; Caciuffo, Roberto

    2012-03-01

    Actinide materials play a special role in condensed matter physics, spanning behaviours of itinerant d-electron and localized 4f-electron materials. This duality of the 5f electrons confer to actinide-based intermetallic compounds a broad variety of physical properties such as magnetic or multipolar ordering, heavy fermion behaviour, quantum criticality, unconventional superconductivity... 237Np Mössbauer spectroscopy is a unique microscopic tool for gaining information on the electronic and magnetic properties of Np systems.

  18. The Sensing of Humidity by Surface-Type Ag/FORMYL-TIPPCu(II)/Ag Sensor for Environmental Monitoring

    NASA Astrophysics Data System (ADS)

    Khan, Dil Nawaz; Sayyad, Muhammad Hassan; Tahir, Muhammad; Wahab, Fazal; Yaseen, Muhammad; Ali, Mukhtar; Munawar, Munawar Ali

    2014-06-01

    In this paper, we have studied the effects of changing relative humidity on the electrical parameters and their multi frequency response of the surface type Ag/formyl-TIPPCu(II)/Ag humidity sensors. The silver electrodes of thickness 100 nm were primarily deposited on cleaned glass substrates by thermal evaporator. A gap of 40 μm was created between the electrodes of each device by using mask during the evaporation process. Thin films of formyl-TIPPCu(II) of 140 nm thickness were grown on silver electrodes by thermal sublimation technique. The values of capacitance and resistance of the sensors were found at different humidity levels at frequency of 1, 10 and 100 kHz of AC input signal. A remarkable increase in capacitance and decrease in resistance were observed during the rise of relative humidity from 45% to 95% RH. The hysteresis response of these humidity sensors was also studied at 1 kHz AC signal.

  19. Comparison of preferred orientation and stress in silver thin films on different substrates using x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Zoo, Yeongseok; Alford, T. L.

    2007-02-01

    Silver thin films were deposited on SiO2 and polyethylene naphthalate (PEN) using e-beam evaporation. X-ray diffraction techniques were used to investigate the influence of substrate morphology on the Ag film's texture. Different modes of texture were observed in Ag thin films on SiO2 and PEN. Detailed information regarding spatial distribution of specific {hkl } planes was obtained by conducting pole figure analyses. A typical stress measurement technique for thin films, sin2ψ analysis, was performed to study how the surface morphology of the various substrates affected the stress induced during the texture evolution of the thin films. Based on the data from this study, the preferred orientation and stress of Ag thin films on SiO2 and PEN were discussed.

  20. Down-regulation of tissue N:P ratios in terrestrial plants by elevated CO2

    NASA Astrophysics Data System (ADS)

    Deng, Q.; Hui, D.; Luo, Y.; Elser, J. J.; Wang, Y.; Loladze, I.; Zhang, Q.; Dennis, S.

    2015-12-01

    Increasing atmospheric CO2 concentrations generally alter element stoichiometry in plants. However, a comprehensive evaluation of the elevated CO2 impact on plant nitrogen:phosphorus (N:P) ratios and the underlying mechanism has not been conducted. We synthesized the results from 112 previously published studies using meta-analysis to evaluate the effects of elevated CO2 on the N:P ratio of terrestrial plants and to explore the underlying mechanism based on plant growth and soil P dynamics. Our results show that terrestrial plants grown under elevated CO2 had lower N:P ratios in both above- and below-ground biomass across different ecosystem types. The response ratio for plant N:P was negatively correlated with the response ratio for plant growth in croplands and grasslands, and showed a stronger relationship for P than for N. In addition, the CO2-induced down-regulation of plant N:P was accompanied by 19.3% and 4.2% increases in soil phosphatase activity and labile P, respectively, and a 10.1% decrease in total soil P. Our results show that down-regulation of plant N:P under elevated CO2 corresponds with accelerated soil P cycling. These findings should be useful for better understanding of terrestrial plant stoichiometry in response to elevated CO2 and of the underlying mechanisms affecting nutrient dynamics under climate change.