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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. PMID:20557895

  2. Mechanistic understanding of reduced AgNP phytotoxicity induced by extracellular polymeric substances.

    PubMed

    Li, Cheng-Cheng; Wang, Yu-Jun; Dang, Fei; Zhou, Dong-Mei

    2016-05-01

    A knowledge gap concerning the potential effects of extracellular polymeric substances (EPS), a common organic material but highly variable in their composition of microbial origin, on the fate and phytotoxicity of silver nanoparticles (AgNP) still remains. A 48-h root elongation toxicity test showed that AgNP toxicity to wheat Triticum aestivum L. was dramatically alleviated by EPS isolated from Pseudomonas putida, as revealed by 7-59% increase in relative root elongation (RRE), 8-99% increase in root weight, 27-32% decrease in malondialdehyde (MDA) content and 11-43% decrease in H2O2 content compared to the treatment with AgNP in the absence of EPS. This was coincident with 7-69% decrease in root Ag concentrations. Our results showed that EPS could protect wheat seedlings from AgNP toxicity by reducing dissolved Ag concentration ([Ag]diss) and by forming AgNP-EPS complex. The FTIR spectra further showed that the amide, carboxyl, and phosphoryl functional groups of EPS were involved in binding with AgNP and/or Ag(+). All these processes worked simultaneously to reduce AgNP bioavailability, and subsequently mitigate AgNP toxicity. These findings highlight the importance of EPS in AgNP biogeochemistry in the terrestrial environment. EPS could be highly useful in developing strategies to counteract the phytotoxicty of metal-based nanoparticles in crops. PMID:26808239

  3. CTAB micelles assisted rGO-AgNP hybrids for SERS detection of polycyclic aromatic hydrocarbons.

    PubMed

    Jiang, Meng; Qian, Zhijiang; Zhou, Xufeng; Xin, Xing; Wu, Jinghua; Chen, Chao; Zhang, Gongjun; Xu, Gaojie; Cheng, Yuchuan

    2015-09-01

    A structure of hexadecyl trimethyl ammonium bromide (CTAB) micelle-assisted reduced graphene oxide-Ag nanoparticle (rGO-AgNP) hybrids is designed and fabricated for SERS detection of nonpolar polycyclic aromatic hydrocarbons (PAHs), in which CTAB micelles act as the host material to capture PAH molecules. This method provides stable aqueous suspensions of functionalized graphene with an alkyl chain, since the rGO-AgNP hybrids do not need to be pre-modified by CTAB. The result shows that the CTAB-assisted rGO-AgNP substrate has excellent SERS performance toward PAHs and ideal stability under continuous laser radiation. With further optimization, the detection limits of pyrene and perylene were 10(-6) M and 10(-7) M, respectively. Two different PAH molecules could be detected simultaneously by their characteristic peaks. PMID:25483919

  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. 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

  6. 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.

  7. 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

  8. Cytotoxicity of Subtoxic AgNP in Human Hepatoma Cell Line (HepG2) after Long-Term Exposure

    PubMed Central

    Nowrouzi, Azin; Meghrazi, Khadijeh; Golmohammadi, Taghi; Golestani, Abolfazl; Ahmadian, Shahin; Shafiezadeh, Mahshid; Shajary, Zahra; Khaghani, Shahnaz; Amiri, Azita

    2010-01-01

    Background: We aimed at evaluating the toxicity effects of low (subtoxic) concentrations of silver nanoparticles (AgNP, 5-10 nm) in human hepatoblastoma (HepG2) cell line after and during a period of about one month. Methods: XTT and MTT assays were used to draw a dose-response curve; IC50 (half maximal inhibitory concentration) value of the AgNP on HepG2 cells was calculated to be 2.75-3.0 mg/l. The cells were exposed to concentrations of 0% (control), 1%, 4% and 8% IC50 of AgNP (corresponding to 0.00, 0.03, 0.12 and 0.24 mg/l of AgNP, respectively) for four consecutive passages. The treated cells were compared to the control group with respect to morphology and proliferation at the end of the period. Results: The biochemical studies revealed significant increases of lactate dehydrogenase and alanine aminotransferase enzyme activity in the culture media of cells receiving 4% and 8% IC50; the increases in the aspartate aminotransferase enzyme activity and nitric oxide concentration became significant at 8% IC50. In the cell extracts, the average total protein and activity of glutathione peroxidase enzyme remained unchanged; the decrease in the average content of glutathione (GSH) and superoxide dismutase (SOD) activity became significant at 4% and 8% IC50. There were increases in lipid peroxidation (significant at 4% and 8% IC50) and cytochrome c content (significant at 8% IC50). The accumulations of the effects, during the experiment from one generation to the next, were not statistically remarkable except in cases of GSH and SOD. The results indicate clearly the involvement of oxidative changes in the cells after exposure to low doses of AgNP. Conclusion: The results might help specify a safer amount of AgNP for use in different applications. PMID:20683495

  9. 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.

  10. 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.

  11. 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. PMID:26739438

  12. 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

  13. 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

  14. Formation of surface oxides and Ag2O thin films with atomic oxygen on Ag(111)

    NASA Astrophysics Data System (ADS)

    Derouin, Jonathan; Farber, Rachael G.; Heslop, Stacy L.; Killelea, Daniel R.

    2015-11-01

    The nature of the oxygen species adsorbed to silver surfaces is a key component of the heterogeneously catalyzed epoxidation of ethylene and partial oxidation of methanol over silver catalysts. We report the formation of two different silver-oxygen species depending on the flux and energy of incident gas-phase oxygen atoms on an Ag(111) surface. A combination of surface science techniques was used to characterize the oxidized surfaces. Atomic oxygen was generated with an Ir filament; lower temperatures created surface oxides previously reported. When O was deposited with a higher filament temperature, the surface became highly corrugated, little subsurface oxygen was observed, and thin layers of Ag2O were likely formed. These results show that the energy and flux of oxygen are important parameters in the chemical identity and abundance of oxygen on silver surfaces and suggest that formation of the Ag2O thin film hinders formation of subsurface oxygen.

  15. 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

  16. Real-Space Microscopic Electrical Imaging of n+-p Junction Beneath Front-Side Ag Contact of Multicrystalline Si Solar Cells

    SciTech Connect

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

    2012-04-15

    We investigated the quality of the n+-p diffused junction beneath the front-side Ag contact of multicrystalline Si solar cells by characterizing the uniformities of electrostatic potential and doping concentration across the junction using the atomic force microscopy-based electrical imaging techniques of scanning Kelvin probe force microscopy and scanning capacitance microscopy. We found that Ag screen-printing metallization fired at the over-fire temperature significantly degrades the junction uniformity beneath the Ag contact grid, whereas metallization at the optimal- and under-fire temperatures does not cause degradation. Ag crystallites with widely distributed sizes were found at the Ag-grid/emitter-Si interface of the over-fired cell, which is associated with the junction damage beneath the Ag grid. Large crystallites protrude 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 junction-quality degradation, based on emitter Si melting at the temperature around the Ag-Si eutectic point during firing, and subsequent re-crystallization with incorporation of Ag and other impurities and with formation of crystallographic defects during quenching. The effect of this junction damage on solar cell performance is discussed.

  17. Thermoelectric Generators from AgBiTe and AgSbTe Thin Films Modified by High-Energy Beam

    NASA Astrophysics Data System (ADS)

    Budak, S.; Guner, S.; Muntele, C.; Ila, D.

    2015-06-01

    The ternary chalcogenides AgBiTe2 and AgSbTe2 belong to the family of semiconductors with disordered NaCl cubic structure in which Ag and Sb occupy metal sublattices. Both compounds are very interesting due to their thermoelectric properties. We have grown single-layer AgBiTe and AgSbTe thin films on silicon (Si) and fused silica (Suprasil) substrates using electron beam deposition. High-energy (MeV) Si-ion bombardment was performed on the thin-film samples at five different fluences between 5 × 1013 ions/cm2 and 7 × 1015 ions/cm2. We have measured the thermoelectric efficiency (figure of merit, ZT) of the fabricated thermoelectric devices by measuring the cross-plane thermal conductivity using the third-harmonic (3 ω) method, the cross-plane Seebeck coefficient, and the in-plane electrical conductivity using the van der Pauw method before and after MeV Si-ion bombardment. Rutherford backscattering spectrometry and the Rutherford Universal Manipulation Program (RUMP) simulation package were used to analyze the elemental composition and thickness of the deposited materials on the substrates. The RUMP simulation gave thicknesses for the AgBiTe and AgSbTe thin films of 270 nm and 188 nm, respectively. The figure of merit for AgBiTe started to decrease from the value of 0.37 for the virgin sample after bombardment. We saw similar decreasing behavior for the AgSbTe thin-film system. The figure of merit for AgSbTe started to decrease from the value of 0.88 for the virgin sample after bombardment. MeV Si-ion bombardment caused changes in the thermoelectric properties of the thin films.

  18. 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.

  19. 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.

  20. Influence of the surface properties on bactericidal and fungicidal activity of magnetron sputtered Ti-Ag and Nb-Ag thin films.

    PubMed

    Wojcieszak, D; Mazur, M; Kaczmarek, D; Mazur, P; Szponar, B; Domaradzki, J; Kepinski, L

    2016-05-01

    In this study the comparative investigations of structural, surface and bactericidal properties of Ti-Ag and Nb-Ag thin films have been carried out. Ti-Ag and Nb-Ag coatings were deposited on silicon and fused silica substrates by magnetron co-sputtering method using innovative multi-target apparatus. The physicochemical properties of prepared thin films were examined with the aid of X-ray diffraction, grazing incidence X-ray diffraction, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy methods. Moreover, the wettability of the surface was determined. It was found that both, Ti-Ag and Nb-Ag thin films were nanocrystalline. In the case of Ag-Ti film presence of AgTi3 and Ag phases was identified, while in the structure of Nb-Ag only silver occurred in a crystal form. In both cases the average size of crystallites was ca. 11 nm. Moreover, according to scanning electron microscopy and atomic force microscopy investigations the surface of Nb-Ag thin films was covered with Ag-agglomerates, while Ti-Ag surface was smooth and devoid of silver particles. Studies of biological activity of deposited coatings in contact with Bacillus subtilis, Pseudomonas aeruginosa, Enterococcus hirae, Klebisiella pneumoniae, Escherichia coli, Staphylococcus aureus and Candida albicans were performed. It was found that prepared coatings were bactericidal and fungicidal even in a short term-contact, i.e. after 2 h. PMID:26952401

  1. 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

  2. Low emissivity Ag/Ta/glass multilayer thin films deposited by sputtering

    SciTech Connect

    Park, Sun Ho; Lee, Kee Sun; Sivasankar Reddy, A.

    2011-09-15

    Ta is deposited on a glass substrate as an interlayer for the two-dimensional growth of Ag thin films because Ta has good thermal stability and can induce a negative surface-energy change in Ag/glass. From the transmission electron microscopy results, we concluded that the Ag crystals in the bottom layer (seemingly on Ag/Ta) were flattened; this was rarely observed in the three-dimensional growth mode. Comparing Ag/Ta/glass with Ag/glass, we found that the Ta interlayer was effective in reducing both the resistance and the emissivity, accompanied by the relatively high transmittance in the visible region. In particular, Ag(9 nm)/Ta(1 nm)/glass film showed 0.08 of the emissivity, including {approx}61% of the transmittance in the visible region (wavelength: 550 nm).

  3. 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. PMID:26035249

  4. Co-deposited thin films of YBa 2Cu 3O 7-δ-Ag

    NASA Astrophysics Data System (ADS)

    Moshfegh, A. Z.; Wang, Y. Q.; Sun, Y. Y.; Mesarwi, A.; Hor, P. H.; Ignatiev, A.

    1993-12-01

    The fabrication of high-temperature superconducting YBa 2Cu 3O 7-δ-Ag thin films has been investigated using a high-pressure Ag coevaporation-DC sputtering technique. Various analytical techniques including X-ray diffraction (XRD), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), energy dispersive X-ray analysis (EDX), and Tc measurement have been utilized for characterization of the films. Highly reproducible c-oriented (00 l) films have been prepared in-situ at a relatively low growth temperature (≃670°C) by this technique. The transition temperatures Tc gradually decreased with added Ag from 90 K (0 at.% Ag) to 72 K (22.3 at.% Ag) for the films deposited on MgO (100) substrates. X-ray diffraction indicated that the Ag is in the metallic state as a separate phase with respect to the YBCO and that the c-lattice parameter of the grown films remained unchanged with Ag addition. Surface morphology of the YBCO-Ag films exhibited a particulate-type structure with the grain size increasing as the Ag content increased. The temperature coefficient of the normalized resistance, d R( T)/ R(280 K)/d T, was also noticed to decrease for the Ag- containing samples as compared to Ag-free YBCO films. AES depth profiling identified Ag residing mainly at the YBCO/MgO interface. The effect of Ag addition to the films has been described by a particle growth model.

  5. 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).

  6. Thermal and laser properties of Yb:LuAG for kW thin disk lasers.

    PubMed

    Beil, Kolja; Fredrich-Thornton, Susanne T; Tellkamp, Friedjof; Peters, Rigo; Kränkel, Christian; Petermann, Klaus; Huber, Günter

    2010-09-27

    Thin disk laser experiments with Yb:LuAG (Yb:Lu(3)Al(5)O(12)) were performed leading to 5 kW of output power and an optical-to-optical efficiency exceeding 60%. Comparative analyses of the laser relevant parameters of Yb:LuAG and Yb:YAG were carried out. While the spectroscopic properties were found to be nearly identical, investigations of the thermal conductivities revealed a 20% higher value for Yb:LuAG at Yb(3+)-doping concentrations of about 10%. Due to the superior thermal conductivity with respect to Yb:YAG, Yb:LuAG offers thus the potential of improved performance in high power thin disk laser applications. PMID:20940967

  7. 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...

  8. 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. PMID:27455677

  9. 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

  10. Structural comparison of Ag-Ge-S bulk glasses and thin films

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Jain, Mukul; Dunn, Porter; de Leo, Carter; Boolchand, Punit

    2007-03-01

    Ternary glasses of composition (GeS3)1-xAgx (x=0.1 and 0.2) are studied in form of bulk and thin films. Bulk glasses are synthesized and examined in Raman scattering and SEM. Raman scattering results of bulk glasses show that with increasing x, an increasing fraction of the Ag additive enters the base glass as Ag^+ with S^-anions serving to form thiogermanate species with one, two and three non-bridging S^- species. SEM measurements of the bulk glass show the material is intrinsically phase separated. White colored islands are observed distributed in a dark base. The EDS measurements show islands are Ag rich and the base is relatively Ag deficient. The Ag rich islands are expected to be mainly glassy phase Ag2S. Thin films of same compositions are fabricated using thermal evaporation. Films are evaporated following two different procedures to prevent the material from spitting. One method was preheating outgas and the other method was using tungsten mesh wrapped boats. The stoichiometry and molecular structure of films under each procedure are analyzed by Raman scattering and SEM to be compared with bulk glasses.

  11. Magnetotransport and coupling in nanostructured Co/Ag thin films

    NASA Astrophysics Data System (ADS)

    Bracho Rodríguez, G. J.; Pereira, L. G.; Miranda, M. G. M.; Antunes, A. B.; Baibich, M. N.

    2000-05-01

    We have studied the electrical resistivity and giant magnetoresistance (GMR) of [Co(15 Å)/Ag(45 Å)] 20/Ag(45 Å) multilayers treated at different annealing temperatures. A simulation based on a formal solution of the Boltzmann equation for the electrical resistivity was performed, and the results compared to the experimental results from 4.2 to 300 K. The simulation shows that both the mean free paths and the transmission coefficients are affected by the breaking of the magnetic layers: at lower annealing temperatures, on account of stress relief and other related processes, the mean free paths increase, but the minority spin mean free path for electrons decreases for anneals above 324°C. A simple parameter to measure the coupling present in spin valve systems is proposed. This shows a decrease of the coupling in the first stages of the anneals, with a sudden increase in coupling upon breaking the magnetic layers.

  12. 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.

  13. 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.

  14. Crossover between silicene and ultra-thin Si atomic layers on Ag(111) surfaces

    NASA Astrophysics Data System (ADS)

    Guo, Zhi-Xin; Oshiyama, Atsushi

    2015-04-01

    We report on total-energy electronic structure calculations in the density-functional theory performed for the ultra-thin atomic layers of Si on Ag(111) surfaces. We find several distinct stable silicene structures: \\sqrt{3}× \\sqrt{3}, 3 × 3, \\sqrt{7}× \\sqrt{7} with the thickness of Si increasing from monolayer to quad-layer. The structural bistability and tristability of the multilayer silicene structures on Ag surfaces are obtained, where the calculated transition barriers infer the occurrence of the flip-flop motion at low temperature. The calculated scanning tunneling microscope (STM) images agree well with the experimental observations. We also find the stable existence of 2 × 1 π-bonded chain and 7 × 7 dimer-adatom-stacking fault Si(111)-surface structures on Ag(111), which clearly shows the crossover of silicene-silicon structures for the multilayer Si on Ag surfaces. We further find the absence of the Dirac states for multilayer silicene on Ag(111) due to the covalent interactions of the silicene-Ag interface and Si-Si interlayer. Instead, we find a new state near the Fermi level composed of π orbitals located on the surface layer of \\sqrt{3}× \\sqrt{3} multilayer silicene, which satisfies the hexagonal symmetry and exhibits the linear energy dispersion. By examining the electronic properties of 2 × 1 π-bonded chain structures, we find that the surface-related π states of multilayer Si structures are robust on Ag surfaces.

  15. 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.

  16. Surface Thiolation of Al Microspheres to Deposite Thin and Compact Ag Shells for High Conductivity.

    PubMed

    Wang, Yilong; Wen, Jianghong; Zhao, Suling; Chen, Zhihong; Ren, Ke; Sun, Jie; Guan, Jianguo

    2015-12-15

    In this work, we have demonstrated a method for controllable thiolated functionalization coupled with electroless silver plating to achieve aluminum@silver (Al@Ag) core-shell composite particles with thin and compact layers. First, Al microspheres were functionalized by a well-known polymerizable silane coupling agent, i.e., 3-mercaptopropyltrimethoxysilane (MPTMS). Decreasing the ethanol-to-water volume ratio (F) in silane solution produces modification films with high content of thiol groups on Al microspheres, owing to the dehydration of silane molecules with hydroxyl groups on Al microspheres and self-polymerization of silane molecules. Then, ethanol was used as one of the solvents to play a major role in the uniform dispersion of silane coupling agent in the solution, resulting in uniformly distributing and covalently attaching thiol groups on Al microspheres. In electroless silver plating, thiol groups being densely grafted on the surface of Al microspheres favor the heterogeneous nucleation of Ag, since the thiol group can firmly bind with Ag(+) and enable the in situ reduction by the reducing reagent. In this manner, dense Ag nuclei tend to produce thin and compact silver shells on the Al microspheres surfaces. The as-obtained Al@Ag core-shell composite particles show a resistivity as low as (8.58 ± 0.07) × 10(-5) Ω·cm even when the Ag content is as low as 15.46 wt %. Therefore, the as-obtained Al@Ag core-shell composite particles have advantages of low weight, low silver content and high conductivity, which could make it a promising candidate for application in conductive and electromagnetic shielding composite materials. PMID:26574653

  17. A study of Ag/Ag(100) thin film growth with scanning tunneling microscopy

    SciTech Connect

    Wen, J.

    1995-11-01

    Thin films are attracting more and more attention in both the industrial and scientific communities. Many applications of thin films have been developed in industry. By using various growth methods, thin films can be used in optics, microelectronic devices, magnetic recording media, and as protective coatings. In order to improve existing applications and to find new ones, it is essential to understand what makes them so useful in applications and what factors affect their properties. Therefore, an understanding of film growth processes is necessary. Scientifically, many fundamental interactions, such as the interaction between the atoms that comprise the film and substrate, or the interaction between film atoms, are of great interest to surface scientists; studies of these interactions can provide dramatic insights into the nature of thin films and therefore, can further drive technology forward. In every application, the film structures, including morphology and microstructure, and adhesion between film and substrate are critical to the film`s properties and therefore its performance. Studies of the mechanisms that control film morphology, microstructure and adhesion thus are important. Film growth kinetics can provide important information regarding the film structure and adhesion. Film growth is an atomistic process. The chemistry and physics of the system can be better understood if the information provided is at an atomic level.

  18. 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.

  19. 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.

  20. The Characteristics of an Antibacterial TiAgN Thin Film Coated by Physical Vapor Deposition Technique.

    PubMed

    Kang, Byeong-Mo; Jeong, Woon-Jo; Park, Gye-Choon; Yoon, Dong-Joo; Ahn, Ho-Geun; Lim, Yeong-Seog

    2015-08-01

    In this work, we found the characteristics of an antibacterial TiAgN thin film coated on the pure titanium specimen via the physical vapor deposition process (PVD). TiAgN thin films were coated using TiAg alloy targets by arc ion plating method. Changing the process parameters, the surface analysis of TiAgN thin film was observed by FE-SEM and the force of adhesion was measured with Scratch Tester. The proliferation of human gingival fibroblast (HGF) cells was examined by XTT test assay and the antibacterial properties were investigated by culturing Streptococus Mutans (KCTC 3065) using paper disk techniques. At the result of experiment, cytotoxic effects were not found and the antibacterial effects against Streptococus Mutans were appeared over 5 wt% TiAgN specimens. PMID:26369190

  1. Photodarkening Effect in a-(GaSe){sub 90}Ag{sub 10} Thin Films

    SciTech Connect

    Gupta, Shikha; Mustafa, F. I.; Saini, G. S. S.; Goyal, Navdeep; Tripathi, S. K.

    2011-12-12

    The present paper reports the laser induced changes on the optical properties of a-(GaSe){sub 90}Ag{sub 10} thin films prepared by thermal evaporation technique. Thin film samples, on glass substrate, were exposed to laser light of wavelength {lambda} = 532 nm for different exposure times, t{sub E}(t{sub E}=0{sub s}, 500 s, 1000 s and 3000 s). Optical parameters like absorption coefficient and optical energy gap of as- deposited thin film and their laser induced changes were studied at three different times of exposure. The value of absorption coefficient of these thin film increases on exposing the film to laser irradiation. The optical absorption edge shift to lower photon energy i.e. the Photodarkening (PD) effect occurs. The results have been explained on the basis of structural changes that are occurring after the laser irradiation.

  2. 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.

  3. 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.

  4. Nanocomposite Ag:TiN thin films for dry biopotential electrodes

    NASA Astrophysics Data System (ADS)

    Pedrosa, P.; Machado, D.; Lopes, C.; Alves, E.; Barradas, N. P.; Martin, N.; Macedo, F.; Fonseca, C.; Vaz, F.

    2013-11-01

    Silver-added titanium nitride (Ag:TiN) thin films were deposited by DC reactive sputtering with Ag contents ranging from 0 to ˜50 at.% on silicon and glass substrates, aiming at studying their potential application as bio-electrodes. The coatings were characterised regarding their composition, morphology and structure, and their influence on the variation of the electrical resistivity and thermal properties. The sputtered films' behaviour was consistently divided into three main zones, defined mainly by the amount of Ag incorporated and the corresponding changes in the structural and morphological features, which affected both the electrical and thermal response of the films. With increasing Ag concentration, the coatings evolve from a nitride/compound-like behaviour to a metallic-like one. Resistivity values suffer a strong decrease due to the increase of compactness of the coatings and the formation of highly conductive Ag phases, counterbalancing the grain size decrease effects promoted by the hindered growth of the crystalline TiN phases. In good agreement with the electrical resistivity evolution, a similar trend was found in the effusivity values, reflecting a significant degradation of the heat conduction mechanisms in the films as the silver content was increased.

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. High brightness continuous wave ceramic Yb:LuAG thin-disk laser.

    PubMed

    Peng, Yuan Han; Cheng, James; Cheah, Yan Ying; Lai, Kin Seng; Lau, Ernest; Ang, Seok Khim

    2015-07-27

    We report on a ceramic Yb:LuAG thin-disk laser in continuous wave operation. The Yb:LuAG ceramic was fabricated using solid-state reactive sintering method. In multi-mode operation in open-air, an output power of 1.74 kW with an optical-to-optical efficiency of 65.0% and slope efficiency of 71.2% was obtained. In near-fundamental mode operation we obtained an output power of 1.29 kW and an average beam quality factor of M2 = 1.44 with an optical-to-optical efficiency of 48.2%. The near-fundamental mode result was realized with a simple evacuated, stable resonator cavity with just the thin-disk gain medium and output coupler. To the best of the authors' knowledge, this is not only the first time more than 1 kW has been demonstrated from a ceramic Yb:LuAG medium, but this is also currently the brightest continuous wave Yb-doped ceramic laser. PMID:26367619

  11. Morphology and N₂ Permeance of Sputtered Pd-Ag Ultra-Thin Film Membranes.

    PubMed

    Fernandez, Ekain; Sanchez-Garcia, Jose Angel; Viviente, Jose Luis; van Sint Annaland, Martin; Gallucci, Fausto; Tanaka, David A Pacheco

    2016-01-01

    The influence of the temperature during the growth of Pd-Ag films by PVD magnetron sputtering onto polished silicon wafers was studied in order to avoid the effect of the support roughness on the layer growth. The surfaces of the Pd-Ag membrane films were analyzed by atomic force microscopy (AFM), and the results indicate an increase of the grain size from 120 to 250-270 nm and film surface roughness from 4-5 to 10-12 nm when increasing the temperature from around 360-510 K. After selecting the conditions for obtaining the smallest grain size onto silicon wafer, thin Pd-Ag (0.5-2-µm thick) films were deposited onto different types of porous supports to study the influence of the porous support, layer thickness and target power on the selective layer microstructure and membrane properties. The Pd-Ag layers deposited onto ZrO₂ 3-nm top layer supports (smallest pore size among all tested) present high N₂ permeance in the order of 10(-6) mol·m(-2)·s(-1)·Pa(-1) at room temperature. PMID:26875977

  12. 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.

  13. Aging and annealing effects on properties of Ag-N dual-acceptor doped ZnO thin films

    SciTech Connect

    Swapna, R.; Amiruddin, R.; Santhosh Kumar, M. C.

    2013-02-05

    Ag-N dual acceptor doping into ZnO has been proposed to realize p-ZnO thin film of different concentrations (1, 2 and 4 at.%) by spray pyrolysis at 623 K and then 4 at.% films annealed at 673 K and 723 K for 1 hr. X-ray diffraction studies reveal that all the films are preferentially oriented along (002) plane. Energy dispersive spectroscopy (EDS) confirms the presence of Ag and N in 2 at.% ZnO:(Ag, N) film. Hall measurement shows that 4 at.% ZnO:(Ag, N) film achieved minimum resistivity with high hole concentration. The p-type conductivity of the ZnO:(Ag, N) films is retained even after 180 days. Photoluminescence (PL) spectra of ZnO:(Ag, N) films show low density of native defects.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Preparation and characterization of double layer thin films ZnO/ZnO:Ag for methylene blue photodegradation

    NASA Astrophysics Data System (ADS)

    Wibowo, Singgih; Sutanto, Heri

    2016-02-01

    Double layer (DL) thin films of zinc oxide and silver-doped zinc oxide (ZnO/ZnO:Ag) were deposited on glass substrate by sol-gel spray coating technique. The prepared thin films were subjected for optical and photocatalytic studies. UV-visible transmission spectra shows that the subtitution of Ag in ZnO leads to band gap reduction. The influence of Ag doping on the photocatalytic activity of ZnO for the degradation of methylene blue dye was studied under solar radiation. The light absorption over an extended visible region by Ag ion doping in ZnO film contributed equally to improve the photocatalytic activity up to 98.29%.

  1. Epitaxial growth of lead zirconium titanate thin films on Ag buffered Si substrates using rf sputtering

    SciTech Connect

    Wang Chun; Laughlin, David E.; Kryder, Mark H.

    2007-04-23

    Epitaxial lead zirconium titanate (PZT) (001) thin films with a Pt bottom electrode were deposited by rf sputtering onto Si(001) single crystal substrates with a Ag buffer layer. Both PZT(20/80) and PZT(53/47) samples were shown to consist of a single perovskite phase and to have the (001) orientation. The orientation relationship was determined to be PZT(001)[110](parallel sign)Pt(001)[110](parallel sign)Ag(001)[110](parallel sign)Si(001)[110]. The microstructure of the multilayer was studied using transmission electron microscopy (TEM). The electron diffraction pattern confirmed the epitaxial relationship between each layer. The measured remanent polarization P{sub r} and coercive field E{sub c} of the PZT(20/80) thin film were 26 {mu}C/cm{sup 2} and 110 kV/cm, respectively. For PZT(53/47), P{sub r} was 10 {mu}C/cm{sup 2} and E{sub c} was 80 kV/cm.

  2. 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.

  3. 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).

  4. Optical properties of Ag nanoclusters formed by irradiation and annealing of SiO2/SiO2:Ag thin films

    NASA Astrophysics Data System (ADS)

    Güner, S.; Budak, S.; Gibson, B.; Ila, D.

    2014-08-01

    We have deposited five periodic SiO2/SiO2 + Ag multi-nano-layered films on fused silica substrates using physical vapor deposition technique. The co-deposited SiO2:Ag layers were 2.7-5 nm and SiO2 buffer layers were 1-15 nm thick. Total thickness was between 30 and 105 nm. Different concentrations of Ag, ranging from 1.5 to 50 molecular% with respect to SiO2 were deposited to determine relevant rates of nanocluster formation and occurrence of interaction between nanoclusters. Using interferometry as well as in situ thickness monitoring, we measured the thickness of the layers. The concentration of Ag in SiO2 was measured with Rutherford Backscattering Spectrometry (RBS). To nucleate Ag nanoclusters, 5 MeV cross plane Si ion bombardments were performed with fluence varying between 5 × 1014 and 1 × 1016 ions/cm2 values. Optical absorption spectra were recorded in the range of 200-900 nm in order to monitor the Ag nanocluster formation in the thin films. Thermal annealing treatment at different temperatures was applied as second method to form varying size of nanoclusters. The physical properties of formed super lattice were criticized for thermoelectric applications.

  5. Structuring of DLC:Ag nanocomposite thin films employing plasma chemical etching and ion sputtering

    NASA Astrophysics Data System (ADS)

    Tamulevičius, Tomas; Tamulevičienė, Asta; Virganavičius, Dainius; Vasiliauskas, Andrius; Kopustinskas, Vitoldas; Meškinis, Šarūnas; Tamulevičius, Sigitas

    2014-12-01

    We analyze structuring effects of diamond like carbon based silver nanocomposite (DLC:Ag) thin films by CF4/O2 plasma chemical etching and Ar+ sputtering. DLC:Ag films were deposited employing unbalanced reactive magnetron sputtering of silver target with Ar+ in C2H2 gas atmosphere. Films with different silver content (0.6-12.9 at.%) were analyzed. The films (as deposited and exposed to plasma chemical etching) were characterized employing scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS), optical microscopy, ultraviolet-visible light (UV-VIS) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. After deposition, the films were plasma chemically etched in CF4/O2 mixture plasma for 2-6 min. It is shown that optical properties of thin films and silver nano particle size distribution can be tailored during deposition changing the magnetron current and C2H2/Ar ratio or during following plasma chemical etching. The plasma etching enabled to reveal the silver filler particle size distribution and to control silver content on the surface that was found to be dependent on Ostwald ripening process of silver nano-clusters. Employing contact lithography and 4 μm period mask in photoresist or aluminum the films were patterned employing CF4/O2 mixture plasma chemical etching, direct Ar+ sputtering or combined etching processes. It is shown that different processing recipes result in different final grating structures. Selective carbon etching in CF4/O2 gas mixture with photoresist mask revealed micrometer range lines of silver nanoparticles, while Ar+ sputtering and combined processing employing aluminum mask resulted in nanocomposite material (DLC:Ag) micropatterns.

  6. Capping effect in magnetic properties of Ag ultra-thin films on Co/Pt(1 1 1)

    NASA Astrophysics Data System (ADS)

    Wu, Y. E.; Su, C. W.; Chen, F. C.; Shern, C. S.; Chen, R. H.

    2002-02-01

    Magneto-optical Kerr effect was used to study the changes of the magnetic property for Ag ultra-thin films deposited on Co/Pt (1 1 1) surface. The perpendicular magnetic anisotropy has a significant enhancement when the system is annealed and the Co-Pt alloy is formed. The magnetization disappears at lower temperatures, and appears at higher temperature after 1 ML Ag/1 ML Co/Pt (1 1 1) ultra-thin film was annealed at 710 K. This magnetization is reversible. The thermal energy triggering the motion of the magnetic domain walls is the possible mechanism for the larger magnetization at high temperature.

  7. Theory and practical considerations of multilayer dielectric thin-film stacks in Ag-coated hollow waveguides.

    PubMed

    Bledt, Carlos M; Melzer, Jeffrey E; Harrington, James A

    2014-02-01

    This analysis explores the theory and design of dielectric multilayer reflection-enhancing thin film stacks based on high and low refractive index alternating layers of cadmium sulfide (CdS) and lead sulfide (PbS) on silver (Ag)-coated hollow glass waveguides (HGWs) for low loss transmission at midinfrared wavelengths. The fundamentals for determining propagation losses in such multilayer thin-film-coated Ag hollow waveguides is thoroughly discussed, and forms the basis for further theoretical analysis presented in this study. The effects on propagation loss resulting from several key parameters of these multilayer thin film stacks is further explored in order to bridge the gap between results predicted through calculation under ideal conditions and deviations from such ideal models that often arise in practice. In particular, the effects on loss due to the number of dielectric thin film layers deposited, deviation from ideal individual layer thicknesses, and surface roughness related scattering losses are presented and thoroughly investigated. Through such extensive theoretical analysis the level of understanding of the underlying loss mechanisms of multilayer thin-film Ag-coated HGWs is greatly advanced, considerably increasing the potential practical development of next-generation ultralow-loss mid-IR Ag/multilayer dielectric-coated HGWs. PMID:24514252

  8. 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.

  9. Combinatorial Study of Ag-Te Thin Films and Their Application as Cation Supply Layer in CBRAM Cells.

    PubMed

    Devulder, Wouter; Opsomer, Karl; Meersschaut, Johan; Deduytsche, Davy; Jurczak, Malgorzata; Goux, Ludovic; Detavernier, Christophe

    2015-05-11

    In this work, we investigate binary Ag-Te thin films and their functionality as a cation supply layer in conductive bridge random access memory devices. A combinatorial sputter deposition technique is used to deposit a graded Ag(x)Te(1-x) (0 < x < 1) layer with varying composition as a function of the position on the substrate. The crystallinity, surface morphology, and material stability under thermal treatment as a function of the composition of the material are investigated. From this screening, a narrow composition range between 33 and 38 at% Te is selected which shows a good morphology and a high melting temperature. Functionality of a single Ag(2-δ)Te composition as cation supply layer in CBRAM with dedicated Al2O3 switching layer is then investigated by implementing it in 580 μm diameter dot Pt/Ag(2-δ)Te/Al2O3/Si cells. Switching properties are investigated and compared to cells with a pure Ag cation supply layer. An improved cycling behavior is observed when Te is added compared to pure Ag, which we relate to the ionic conducting properties of Ag2Te and the preferred formation of Ag-Te phases. PMID:25860668

  10. Nano-crystalline Ag-PbTe thermoelectric thin films by a multi-target PLD system

    NASA Astrophysics Data System (ADS)

    Cappelli, E.; Bellucci, A.; Medici, L.; Mezzi, A.; Kaciulis, S.; Fumagalli, F.; Di Fonzo, F.; Trucchi, D. M.

    2015-05-01

    It has been evaluated the ability of ArF pulsed laser ablation to grow nano-crystalline thin films of high temperature PbTe thermoelectric material, and to obtain a uniform and controlled Ag blending, through the entire thickness of the film, using a multi-target system in vacuum. The substrate used was a mirror polished technical alumina slab. The increasing atomic percentage of Ag effect on physical-chemical and electronic properties was evaluated in the range 300-575 K. The stoichiometry and the distribution of the Ag component, over the whole thickness of the samples deposited, have been studied by XPS (X-ray photoelectron spectroscopy) and corresponding depth profiles. The crystallographic structure of the film was analyzed by grazing incidence X-ray diffraction (GI-XRD) system. Scherrer analysis for crystallite size shows the presence of nano-structures, of the order of 30-35 nm. Electrical resistivity of the samples, studied by the four point probe method, as a function of increasing Ag content, shows a typical semi-conductor behavior. From conductivity values, carrier concentration and Seebeck parameter determination, the power factor of deposited films was calculated. Both XPS, Hall mobility and Seebeck analysis seem to indicate a limit value to the Ag solubility of the order of 5%, for thin films of ∼200 nm thickness, deposited at 350 °C. These data resulted to be comparable to theoretical evaluation for thin films but order of magnitude lower than the corresponding bulk materials.

  11. 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.

  12. 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

  13. Low cost, ultra-thin films of reduced graphene oxide-Ag nanoparticle hybrids as SERS based excellent dye sensors

    NASA Astrophysics Data System (ADS)

    Kavitha, C.; Bramhaiah, K.; John, Neena S.; Ramachandran, B. E.

    2015-06-01

    We have employed low cost-thin films of reduced graphene oxide (rGO) with Ag nanoparticle hybrids as surface enhanced Raman scattering (SERS) substrates. The hybrids are prepared by a simple one step liquid/liquid interface method. These hybrid films offer SERS hotspots to detect Rhodamine 6G (R6G) molecules till 1 nM concentration with 1 second accumulation time. The enhancement factor is of the order 108. This excellent SERS enhancement is due to coupled mechanism of surface plasmon, charge transfer and molecular resonances of Ag and R6G along with the synergic effect contributed by rGO and Ag nanoparticles in the hybrid thin film.

  14. Size dependent electron-phonon coupling in N, Li, In, Ga, F and Ag doped ZnO thin films.

    PubMed

    Shinde, S S; Bhosale, C H; Rajpure, K Y

    2012-12-01

    Polarized micro-Raman measurements are performed to study the phonon modes of N, Li, In, Ga, F and Ag doped ZnO thin films, grown by spray pyrolysis on corning glass substrates. The E(2)(high) mode displays a visible asymmetric line shape. The size and dopant dependence onto coupling strength between electron and LO phonon is experimentally estimated. PMID:23010630

  15. 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

  16. 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

  17. 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.

  18. Acetylene trimerization on Ag, Pd and Rh atoms deposited on MgO thin films.

    PubMed

    Judai, Ken; Wörz, Anke S; Abbet, Stéphane; Antonietti, Jean-Marie; Heiz, Ueli; Del Vitto, Annalisa; Giordano, Livia; Pacchioni, Gianfranco

    2005-03-01

    The acetylene trimerization on the group VIII transition metal atoms, Rh and Pd, as well as on Ag atoms supported on MgO thin films has been studied experimentally and theoretically. The three metal atoms with the atomic configurations 4d(8)5s1 (Rh), 4d10s0 (Pd) and 4d(10)5s1 (Ag) behave distinctly differently. The coinage metal atom silver is basically inert for this reaction, whereas Pd is active at 220 and 320 K, and Rh produces benzene in a rather broad temperature range from 350 to ca. 430 K. The origins of these differences are not only the different electronic configurations, leading to a weak interaction of acetylene with silver due to strong Pauli repulsion with the 5s electron but also the different stability and dynamics of the three atoms on the MgO surface. In particular, Rh and Pd atoms interact differently with surface defects like the oxygen vacancies (F centers) and the step edges. Pd atoms migrate already at low temperature exclusively to F centers where the cyclotrimerization is efficiently promoted. The Rh atoms on the other hand are not only trapped on F centers but also at step edges up to about 300 K. Interestingly, only Rh atoms on F centers catalyze the trimerization reaction whereas they are turned inert on the step edges due to strong steric effects. PMID:19791385

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Laser generated Ag and Ag-Au composite nanoparticles for refractive index sensor

    NASA Astrophysics Data System (ADS)

    Navas, M. P.; Soni, R. K.

    2014-09-01

    Localized surface plasmon resonance (LSPR) wavelength of metal nanoparticles (NPs) is highly sensitive to size, shape and the surrounding medium. Metal targets were laser ablated in liquid for preparation of spherical Ag and Ag@Au core-shell NP colloidal solution for refractive index sensing. The LSPR peak wavelength and broadening of the NPs were monitored in different refractive index liquid. Quasi-static Mie theory simulation results show that refractive index sensitivity of Ag, Ag-Au alloy and Ag@Au core-shell NPs increases nearly linearly with size and shell thickness. However, the increased broadening of the LSPR peak with size, alloy concentration and Au shell thickness restricts the sensing resolution of these NPs. Figure-of-merit (FOM) was calculated to optimize the size of Ag NPs, concentration of Ag-Au alloy NPs and Au shell thickness of Ag@Au core-shell NPs. The refractive index sensitivity (RIS) and FOM were optimum in the size range 20-40 nm for Ag NPs. Laser generated Ag@Au NPs of Au shell thickness in the range of 1-2 nm showed optimum FOM, where thin layer of Au coating can improve the stability of Ag NPs.

  6. Thickness Dispersion of Surface Plasmon of Ag Nano-thin Films: Determination by Ellipsometry Iterated with Transmittance Method

    PubMed Central

    Gong, Junbo; Dai, Rucheng; Wang, Zhongping; Zhang, Zengming

    2015-01-01

    Effective optical constants of Ag thin films are precisely determined with effective thickness simultaneously by using an ellipsometry iterated with transmittance method. Unlike the bulk optical constants in Palik's database the effective optical constants of ultrathin Ag films are found to strongly depend on the thickness. According to the optical data two branches of thickness dispersion of surface plasmon energy are derived and agreed with theoretical predication. The thickness dispersion of bulk plasmon is also observed. The influence of substrate on surface plasmon is verified for the first time by using ellipsometry. The thickness dependent effective energy loss function is thus obtained based on this optical method for Ag ultrathin films. This method is also applicable to other ultrathin films and can be used to establish an effective optical database for ultrathin films. PMID:25797217

  7. Thermally induced effect on sub-band gap absorption in Ag doped CdSe thin films

    NASA Astrophysics Data System (ADS)

    Kaur, Jagdish; Sharma, Kriti; Bharti, Shivani; Tripathi, S. K.

    2015-05-01

    Thin films of Ag doped CdSe have been prepared by thermal evaporation using inert gas condensation (IGC) method taking Argon as inert gas. The prepared thin films are annealed at 363 K for one hour. The sub-band gap absorption spectra in the as deposited and annealed thin films have been studied using constant photocurrent method (CPM). The absorption coefficient in the sub-band gap region is described by an Urbach tail in both as deposited and annealed thin films. The value of Urbach energy and number density of trap states have been calculated from the absorption coefficient in the sub-band gap region which have been found to increase after annealing treatment indicating increase in disorderness in the lattice. The energy distribution of the occupied density of states below Fermi level has also been studied using derivative procedure of absorption coefficient.

  8. Ar plasma irradiation improved optical and electrical properties of TiO₂/Ag/TiO₂ multilayer thin film.

    PubMed

    Fang, Yingcui; He, Jinjun; Zhang, Kang; Xiao, Chuanyun; Zhang, Bing; Shen, Jie; Niu, Haihong; Yan, Rong; Chen, Junling

    2015-12-01

    Embedding a thin metal layer between two thin dielectric or semiconductor layers [dielectric/metal/dielectric (DMD)] leads to a kind of transparent electrode that is promising as a substitute for the currently widely applied indium tin oxide electrode. However, the optical and electrical properties of DMD still wait for further improvement. In this study, Ar plasma irradiation (API) was, for the first time to our knowledge, applied to improve the optical and electrical properties of a TiO2/Ag/TiO2 electrode that was fabricated by electron-beam evaporation of TiO2 and electric-resistance heating of high purity Ag under vacuum. Ar plasma was produced by radio frequency glow discharge. The Ag layer was bombarded before the second layer of TiO2 was deposited. The electrode with configuration of TiO2 (24  nm)/Ag(14  nm)/TiO2 (24  nm) after API for 10 s shows excellent performance. The mean transmittance between 370 and 800 nm reaches 94% and the sheet resistance is as low as 6  Ω/sq, while Haacke's figure of merit is as high as 112×10(-3)  Ω(-1). The improvement mechanism is discussed based on field emission scanning electron microscope images and absorption spectra. The improvement is attributed to the fact that API reduces the localized surface plasmon resonance of Ag nanoparticles and makes the Ag film thinner and denser. PMID:26625024

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. Ag y :TiN x thin films for dry biopotential electrodes: the effect of composition and structural changes on the electrical and mechanical behaviours

    NASA Astrophysics Data System (ADS)

    Pedrosa, P.; Machado, D.; Borges, J.; Rodrigues, M. S.; Alves, E.; Barradas, N. P.; Martin, N.; Evaristo, M.; Cavaleiro, A.; Fonseca, C.; Vaz, F.

    2015-04-01

    In the present work, Ag y :TiN x thin films, obtained by reactive DC magnetron sputtering, with decreasing [N]/[Ti] atomic ratios (from 1 to 0.1) and a fixed amount of Ag pellets placed in the erosion zone of a pure Ti target, were studied envisaging their application as biopotential electrodes. The strongly under-stoichiometric samples, [N]/[Ti] = 0.1 and 10 at.% Ag; [N]/[Ti] = 0.2 and 8 at.% Ag, were found to be composed of a N-doped hcp-Ti structure, with possible formation of TiAg or Ti2Ag intermetallics. These samples exhibit high electrical resistivity values and low hardness and reduced modulus. In the set of samples indexed to a transition zone, [N]/[Ti] = 0.3 and 15 at.% Ag; [N]/[Ti] = 0.7 and 32 at.% Ag, a hcp-Ti to fcc-TiN phase transformation took place, giving rise to a disaggregated N-deficient TiN matrix. It correlates with the high resistivity values as well as the higher hardness and reduced modulus values that were obtained. The last identified zone comprised the stoichiometric Ag:TiN x sample—[N]/[Ti] = 1 and 20 at.% Ag. Extensive metallic Ag segregation was detected, contributing to a significant decrease of the resistivity and hardness values.

  14. Surface Plasmons and Optical Properties of TiO2/X(X = Au and Ag) Nanostructure Thin Films

    NASA Astrophysics Data System (ADS)

    Zolanvari, A.; Sadeghi, H.; Norouzi, R.; Ranjgar, A.

    2013-09-01

    TiO2/X(X = Au and Ag) nanolayers are fabricated by depositing TiO2 films using rf magnetron sputtering on thin quartz substrates embedded with Au and Ag nanoparticles. Enhancement of light absorption of the nanostructural layers is observed. These plasmonic and non-plasmonic materials are ordered in geometric arrangements with dimensions that are fractions of the wavelength of light. The light absorption enhancement of synthesized structure in comparison to TiO2 is originated from near-field enhancement caused by the plasmonic effect of metallic nanoparticles, which can be demonstrated by the optical absorption spectra. We show that plasmon modes can exist for the infrared region of the optical spectrum. Also, we analyze the optical properties of the metal-insulator films, in order to clarify the role of metal inclusions in the TiO2 dielectric matrix. Optical band gaps of the nanolayer films are calculated by using Tauc's relation, and the n values of optical band gaps with the variation composition are found from 1.80 to 3.69 eV. Band gap narrowing and absorption in the visible spectral region induced by the incorporation of TiO2/X(X=Au and Ag) nanolayers enable the design of nanostructured thin films to be achieved for photocatalysts and solar energy converters.

  15. Synthesis and characterization of Zn(O,OH)S and AgInS2 layers to be used in thin film solar cells

    NASA Astrophysics Data System (ADS)

    Vallejo, W.; Arredondo, C. A.; Gordillo, G.

    2010-11-01

    In this paper AgInS2 and Zn(O,OH)S thin films were synthesized and characterized. AgInS2 layers were grown by co-evaporation from metal precursors in a two-step process, and, Zn(O,OH)S thin films were deposited from chemical bath containing thiourea, zinc acetate, sodium citrate and ammonia. X-ray diffraction measurements indicated that AgInS2 thin films grown with chalcopyrite structure, and the as-grown Zn(O,OH)S thin films were polycrystalline. It was also found that the AgInS2 films presented p-type conductivity, a high absorption coefficient (greater than 104 cm-1) and energy band-gap Eg of about 1.95 eV, Zn(O,OH),S thin films presented Eg of about 3.89 eV. Morphological analysis showed that under this synthesis conditions Zn(O,OH),S thin films coated uniformly the absorber layer. Additionally, the Zn(O,OH)S kinetic growth on AgInS2 layer was studied also. Finally, the results suggest that these layers possibly could be used in one-junction solar cells and/or as top cell in a tandem solar cell.

  16. Studies on mass attenuation coefficients, effective atomic numbers and electron densities for CoCuAg alloy thin film

    NASA Astrophysics Data System (ADS)

    Apaydın, G.; Cengiz, E.; Tıraşoğlu, E.; Aylıkcı, V.; Bakkaloğlu, Ö. F.

    2009-05-01

    The mass attenuation coefficients for the elements Co, Cu and Ag and a thin film of CoCuAg alloy were measured in the energy range 4.029-38.729 keV. Effective atomic numbers and electron densities were calculated by using these coefficients. The energies were obtained by using secondary targets that were irradiated with gamma-ray photons of 241Am. The x-rays were counted by using a Canberra Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The results were compared with theoretical calculated values and fairly good agreement was found between them within an average experimental error. The mass attenuation coefficients, effective atomic numbers and electron densities were plotted versus photon energy.

  17. 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.

  18. 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

  19. 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.

  20. Influence of oxygen partial pressure on the physical properties of Ag doped NiO thin films

    NASA Astrophysics Data System (ADS)

    Reddy, Y. Ashok Kumar; Reddy, A. Sivasankar; Reddy, P. Sreedhara

    2013-06-01

    Ag doped p-type NiO thin films were successfully deposited by DC reactive magnetron sputtering technique at different oxygen partial pressures in the range 1 × 10-4 - 9 × 10-4 mbar. The structural and morphological properties of the films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). All the deposited films were of polycrystalline nature and exhibited cubic structure with preferential growth. The morphological studies revealed that the surface roughness was increased with increasing oxygen partial pressure up to 5 × 10-4 mbar and decreased at higher oxygen partial pressures.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Novel fabrication of Ag thin film on glass for efficient surface-enhanced Raman scattering.

    PubMed

    Park, Hyoung Kun; Yoon, Jae Keun; Kim, Kwan

    2006-02-14

    This paper describes a very simple electroless-plating method used to prepare optically tunable nanostructured Ag films. Very stable Ag films can be reproducibly fabricated simply by soaking glass substrates in ethanolic solutions of AgNO3 and butylamine. The grain size of silver can be readily controlled to range from 20 to 150 nm, and these nanostructural features correlated well with their UV/vis absorption characteristics, as well as with their surface-enhanced Raman scattering (SERS) activities. It is also very advantageous that the Ag films prepared exhibit very even SERS activity over an area up to hundreds thousand square-micrometers, and the enhancement factor estimated using benzenethiol as a prototype adsorbate reaches approximately 2 x 10(5). Since the proposed method is cost-effective and is suitable for the mass production of diverse Ag films irrespective of the shapes of the underlying substrates, it is expected to play a significant role in the development of surface plasmon-based analytical devices. PMID:16460083

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

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

    NASA Astrophysics Data System (ADS)

    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 AgGaSe2 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 AgGaSe2, showing evidence for the existence of very shallow acceptor levels of 5(1) and 10(1) meV, and thus suggesting the AgGaSe2 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 Ag2Se and Ga2O3 nanometer-scaled surface layers, as well as by Ag2Se inclusions in the bulk and Ag clusters at the layers’ rear side.

  12. 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

  13. 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.

  14. 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. PMID:27230692

  15. 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

  16. 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.

  17. High Ms Fe16N2 thin film with Ag under layer on GaAs substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaowei; Jiang, Yanfeng; Yang, Meiyin; Allard, Lawrence F.; Wang, Jian-Ping

    2016-05-01

    (001) textured Fe16N2 thin film with Ag under layer is successfully grown on GaAs substrate using a facing target sputtering (FTS) system. After post annealing, chemically ordered Fe16N2 phase is formed and detected by X-ray diffraction (XRD). High saturation magnetization (Ms) is measured by a vibrating sample magnetometer (VSM). In comparison with Fe16N2 with Ag under layer on MgO substrate and Fe16N2 with Fe under layer on GaAs substrate, the current layer structure shows a higher Ms value, with a magnetically softer feature in contrast to the above cases. In addition, X-ray photoelectron spectroscopy (XPS) is performed to characterize the binding energy of N atoms. To verify the role of strain that the FeN layer experiences in the above three structures, Grazing Incidence X-ray Diffraction (GIXRD) is conducted to reveal a large in-plane lattice constant due to the in-plane biaxial tensile strain.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Optical properties of (Se{sub 80}Te{sub 20}){sub 100−x}Ag{sub x} (0 ≤ x ≤ 4) thin films

    SciTech Connect

    Singh, D. Kumar, S. Sandhu, S. Thangaraj, R.

    2014-04-24

    Thin films of (Se{sub 80}Te{sub 20}){sub 100−x}Ag{sub x} (0 ≤ x ≤ 4) glasses were prepared by thermal evaporation of the bulk samples. The transmittance (T) and reflection (R) spectra of amorphous thin films were obtained in the spectral region in the range 400–2500 nm. The optical band gap (E{sub g}) has been determined by Tauc’s extrapolation method. The surface morphology has been determined by the Scanning Electron Microscopy (SEM)

  5. 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.

  6. 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.

  7. Optical constants for Ge30- x Se70Ag x (0 ≤ x ≤ 30 at%) thin films based only on their reflectance spectra

    NASA Astrophysics Data System (ADS)

    Aly, K. A.; Dahshan, A.; Yahia, I. S.

    2012-03-01

    In this paper, different homogenous compositions of Ge30- x Se70Ag x (0 ≤ x ≤ 30 at%) thin films were prepared by thermal evaporation. Reflection spectra, R(λ), for the films were measured in the wavelength range 400-2500 nm. A straightforward analysis proposed by Minkov [J. Phys. D: Appl. Phys. 22 (1989) p.1157], based on the maxima and minima of the reflection spectra, allows us to derive the real and imaginary parts of the complex index of refraction and the film thickness of the studied films. Increasing Ag content at the expense of Ge atoms is found to affect the refractive index and the extinction coefficient of the films. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple-DiDomenico model. Optical absorption measurements were used to obtain the fundamental absorption edge as a function of composition. With increasing Ag content, the refractive index increases while the optical band gap decreases. The compositional dependence of the optical band gap for the Ge30- x Se70Ag x (0 ≤ x ≤ 30) thin films is discussed in terms of the chemical bond approach.

  8. 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

  9. 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.

  10. 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.

  11. Effect of N2/Ar on structure and hardness of TaN-Ag thin films deposited by DC cylindrical magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Foadi, Farnaz; Darabi, Elham; Reza Hantehzadeh, Mohammad

    2014-05-01

    TaN-Ag thin films were deposited on a 304 stainless steel substrate by cylindrical DC magnetron sputtering using different ratios of nitrogen to argon gas. The N2 percentages were 1.5%, 3%, 4.5%, 7.5%, 10.5% and 15% by volume. The influence of the N2/Ar ratio on the films morphology, structure and hardness was investigated using Atomic Force Microscopy (AFM), Grazing Incidence X-ray Diffraction (GIXRD), and the nanoindentation method. The amounts of Ta and Ag were determined using Energy Dispersive X-ray Spectroscopy (EDS). The thickness of the deposited films was measured by surface step profilometer. The RMS surface roughness increased for N2 percentages up to 7.5% and then decreased. Grazing results showed different TaN phases and Ag crystalline structures. The hardness of all films was much higher than the hardness of bulk silver or tantalum. The highest hardness value was obtained for 1.5% N2 . The EDS results indicated that the Ag/Ta ratio in the deposited films increases with increasing the N2 amount from 1.5% to 15%. The size of Ag islands on the surface was maximized at 7.5% N2 in the gas mixture. The thicknesses of films were in the range of 400-600 nm.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    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/cm2. 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.

  18. 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.

  19. One-step synthesis of size-tunable Ag nanoparticles incorporated in electrospun PVA/cyclodextrin nanofibers.

    PubMed

    Celebioglu, Asli; Aytac, Zeynep; Umu, Ozgun C O; Dana, Aykutlu; Tekinay, Turgay; Uyar, Tamer

    2014-01-01

    One-step synthesis of size-tunable silver nanoparticles (Ag-NP) incorporated into electrospun nanofibers was achieved. Initially, in situ reduction of silver salt (AgNO3) to Ag-NP was carried out in aqueous solution of polyvinyl alcohol (PVA). Here, PVA was used as reducing agent and stabilizing polymer as well as electrospinning polymeric matrix for the fabrication of PVA/Ag-NP nanofibers. Afterwards, hydroxypropyl-beta-cyclodextrin (HPβCD) was used as an additional reducing and stabilizing agent in order to control size and uniform dispersion of Ag-NP. The size of Ag-NP was ∼8 nm and some Ag-NP aggregates were observed for PVA/Ag-NP nanofibers, conversely, the size of Ag-NP decreased from ∼8 nm down to ∼2 nm within the fiber matrix without aggregation were attained for PVA/HPβCD nanofibers. The PVA/Ag-NP and PVA/HPβCD/Ag-NP nanofibers exhibited surface enhanced Raman scattering (SERS) effect. Moreover, antibacterial properties of PVA/Ag-NP and PVA/HPβCD/Ag-NP nanofibrous mats were tested against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. PMID:24274573

  20. 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

  1. 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.

  2. Granular L1{sub 0} FePt-B and FePt-B-Ag (001) thin films for heat assisted magnetic recording

    SciTech Connect

    Granz, Steven D.; Barmak, Katayun; Kryder, Mark H.

    2012-04-01

    A comparison was made of FePt-B and FePt-B-Ag thin films having different volume contents of boron, which were RF sputtered with in-situ heating at 425-575 deg. C onto Si substrates with 20 nm thick (002) MgO. By introducing boron into FePt and varying the sputtering conditions, films with grain sizes ranging from 2.5 to 10 nm were produced. The boron promoted columnar growth, but made ordering more difficult. However, by adding Ag into FePt-B, ordering improved while coercivity increased from 7 to 11 kOe with no significant impact on the microstructure. We obtained films with grain sizes down to 2.5 nm with center-to-center spacing of 3.1 nm. The reduced grain size, columnar microstructure and increase in ordering and coercivity by adding Ag into the FePt-B thin films are favorable for application in heat assisted magnetic recording.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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. PMID:25281786

  9. Photocathode tunability: The photoemissive properties of ultra-thin multilayered MgO/Ag/MgO films synthesized by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Velazquez, Daniel Gomez

    Much of the early development of photocathode materials was aimed at the growth of photoemissive thin films with low work function, and high quantum efficiency (QE). It has been shown, both theoretically and experimentally, that metal-insulator junctions can lead to the modification of the work function and QE for coverages of a few monolayers of metal oxides on metallic substrates. However, the production of electron beams suitable for new photoinjector technologies often requires low emittance beams from the cathode itself. A theoretical model [Phys. Rev. Lett. 104, 046801 (2010)] based on a multilayered structure of MgO/Ag(001)/MgO with 4 monolayers of Ag(001) flanked by n monolayers (ML) of MgO indicates the possibility to reduce the surface work function and photoelectron beam emittance when the thickness n of the MgO layers is 2 or 3 monolayers. These predictions were tested experimentally. Synthesis of multilayered MgO/Ag/MgO films was performed using a custom-built pulsed laser deposition (PLD) system. In-situ growth monitoring was carried out by Reflection High-Energy Electron Diffraction (RHEED). Ex-situ techniques such as Scanning Tunneling Microscopy (STM), Scanning Electron Microscopy/Energy Dispersive Spectroscopy (EDS) and Photoelectron Spectroscopy (PES) were used to show the formation of the crystalline and chemical structure. A custom-built Kelvin Probe/photocurrent-detector system was used to measure the work function and QE of the samples. Angle Resolved Photoelectron Spectroscopy was used to measure the angular photoelectron yield. Simultaneous reduction of work function and increase of QE was observed for (001) oriented multilayers of various thicknesses with respect to that of a bare Ag/MgO(001) surface. Work function measurements of multilayers of various thicknesses in the (111) orientation also showed a monotonic reduction with respect to that of a bare Ag/Si(111) surface. Angular emission was compared for a MgO/Ag/MgO multilayer

  10. 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.

  11. Laser-induced changes on optical band gap of amorphous and crystallized thin films of Se 75S 25-xAG x

    NASA Astrophysics Data System (ADS)

    Al-Ghamdi, A. A.; Khan, Shamshad A.

    2009-11-01

    Optical band gap of amorphous, crystallized, laser induced amorphous and laser induced crystallized films of Se 75S 25-xAg x ( x=4, 6 and 8) glassy alloys was studied from absorption spectra. The amorphous and crystallized films were induced by pulse laser for 10 min. After laser irradiation on amorphous and crystalline films, optical band gap was measured. It has been found that the mechanism of the optical absorption follows the rule of indirect transition. The amorphous thin films show an increase in the optical band gap, while the crystallized (thermally annealed) thin films show a decrease in the optical band gap by inducing laser irradiation. Crystallization and amorphization of chalcogenide films were accompanied with the change in the optical band gap. The change in optical energy gap could be determined by identification of the transformed phase. These results are interpreted in terms of concentration of localized states due to shift in Fermi level.

  12. Thermally deposited Ag-doped CdS thin film transistors with high-k rare-earth oxide Nd{sub 2}O{sub 3} as gate dielectric

    SciTech Connect

    Gogoi, P.

    2013-03-15

    The performance of thermally deposited CdS thin film transistors doped with Ag has been reported. Ag-doped CdS thin films have been prepared using chemical method. High dielectric constant rare earth oxide Nd{sub 2}O{sub 3} has been used as gate insulator. The thin film trasistors are fabricated in coplanar electrode structure on ultrasonically cleaned glass substrates with a channel length of 50 {mu}m. The thin film transistors exhibit a high mobility of 4.3 cm{sup 2} V{sup -1} s{sup -1} and low threshold voltage of 1 V. The ON-OFF ratio of the thin film transistors is found as 10{sup 5}. The TFTs also exhibit good transconductance and gain band-width product of 1.15 Multiplication-Sign 10{sup -3} mho and 71 kHz respectively.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. Thin films composed of Ag nanoclusters dispersed in TiO2: Influence of composition and thermal annealing on the microstructure and physical responses

    NASA Astrophysics Data System (ADS)

    Borges, J.; Rodrigues, M. S.; Lopes, C.; Costa, D.; Couto, F. M.; Kubart, T.; Martins, B.; Duarte, N.; Dias, J. P.; Cavaleiro, A.; Polcar, T.; Macedo, F.; Vaz, F.

    2015-12-01

    Noble metal powders containing gold and silver have been used for many centuries, providing different colours in the windows of the medieval cathedrals and in ancient Roman glasses. Nowadays, the interest in nanocomposite materials containing noble nanoparticles embedded in dielectric matrices is related with their potential use for a wide range of advanced technological applications. They have been proposed for environmental and biological sensing, tailoring colour of functional coatings, or for surface enhanced Raman spectroscopy. Most of these applications rely on the so-called localised surface plasmon resonance absorption, which is governed by the type of the noble metal nanoparticles, their distribution, size and shape and as well as of the dielectric characteristics of the host matrix. The aim of this work is to study the influence of the composition and thermal annealing on the morphological and structural changes of thin films composed of Ag metal clusters embedded in a dielectric TiO2 matrix. Since changes in size, shape and distribution of the clusters are fundamental parameters for tailoring the properties of plasmonic materials, a set of films with different Ag concentrations was prepared. The optical properties and the thermal behaviour of the films were correlated with the structural and morphological changes promoted by annealing. The films were deposited by DC magnetron sputtering and in order to promote the clustering of the Ag nanoparticles the as-deposited samples were subjected to an in-air annealing protocol. It was demonstrated that the clustering of metallic Ag affects the optical response spectrum and the thermal behaviour of the films.

  19. Granular L10 FePt:X (X = Ag, B, C, SiOx, TaOx) thin films for heat assisted magnetic recording

    NASA Astrophysics Data System (ADS)

    Granz, Steven D.; Barmak, Katayun; Kryder, Mark H.

    2013-03-01

    Ordered L10 FePt thin films are of interest as potential Heat Assisted Magnetic Recording media. In order to achieve the microstructure and magnetic properties to support recording at densities beyond 1 Tbit/in2, it is necessary to add segregants into the FePt films. In this work, the effects of a number of segregants, X, on the microstructure and magnetic properties of FePt:X (X = Ag, B, C, SiO x , TaO x ) thin films, deposited by RF sputtering with various volume content (0-50%), various in-situ heating temperatures (450-600 °C), various Ar pressures (10-40 mtorr) and various sputtering powers (25-200 W) onto 1'' Si substrates with a MgO texture (002) underlayer (20 nm), were investigated. It was observed that introducing segregants (B, C, SiO x , and TaO x ) into the FePt reduced ordering and grain size of the FePt:X thin films. Ag was found to offset the reduction of ordering in the FePt:X films. The B, SiO x and TaO x promoted columnar growth whereas C promoted a secondary nucleation layer but produced the least reduction of ordering. By varying the volume content of the segregants, the grain size of the FePt:X can be controllably reduced throughout the 2.5-10 nm range. It was found that TaO x produced the best exchange decoupling, thermal durability, grain isolation and hindered grain coalescence as compared with the films deposited with B, C or SiO x . With the FePt:C:Ag films sputtered at 450 °C, a perpendicular coercivity measured at room temperature as high as 25 kOe was achieved; whereas with B, SiO x , and TaO x , perpendicular coercivities as high as 11 kOe were obtained. These FePt:X thin films with small grain size, columnar microstructure and high coercivity are believed to be favorable for application in Heat Assisted Magnetic Recording. The role of surface energies of FePt and the segregant in columnar growth of FePt grains is discussed.

  20. Level structures in Np240

    NASA Astrophysics Data System (ADS)

    Sood, P. C.; Gowrishankar, R.; Dora, Ashish Kumar

    2014-03-01

    Whereas the 7.2 min Np240, first identified over 60 years ago, has been assigned conflicting configuration by various investigators, the 62 min Np240 is assigned a "probable" configuration, deduced in each case by primarily focusing on just a single β-connected pair of levels in either Np240 (β-) 240Pu or 240U (β-) Np240 decay. We evaluate the level energies of physically admissible 2qp configurations in 93240Np147 employing a three-step procedure, with experimental inputs at each step, and using a well tested two-particle rotor model with inclusion of residual n-p interaction and other contributions. This exercise clearly establishes that the 62 min Np240 and the 7.2 min Np240 isomers constitute a Gallagher-Moszkowski (GM) doublet corresponding to the two-quasiparticle (2qp) configuration 5+{p5/2+[642]±n5/2+[622]}0+ with JπK=1+0 for the higher-lying 7.2 min isomer. This assignment is conclusively confirmed in a level-by-level analysis of data on 23 β transitions in these decays. Structures of a few other Np240 levels populated in 240U β decay are also discussed.

  1. 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

  2. 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.

  3. Synthesis of Ultra-Thin Single Crystal MgO/Ag/MgO Multilayer for Controlled Photocathode Emissive Properties

    NASA Astrophysics Data System (ADS)

    Velazquez, Daniel; Seibert, Rachel; Yusof, Zikri; Terry, Jeff; Spentzouris, Linda

    2015-03-01

    Developments of new accelerator technologies such as free-electron lasers and high-energy accelerators, among others, continuously set requirements for particle sources to produce higher beam flux. The emissive properties of these photocathodes directly influence the accelerator beam flux and thus the performance of the accelerator as a whole. The objective of this project is to test the possibility of engineering the photoemissive properties of materials for potential use as photocathodes. For this purpose we use a Density Functional Theory calculations by collaborator Karoly Nemeth et al. [Phys. Rev. Lett. 104, 046801, 2010], which predict a thickness dependent change in the band structure that results in a change in the work function and dispersion of occupied states at the Fermi level. Multilayered MgO/Ag/MgO in the crystallographic orientations (001) and (111) were grown on Ag/MgO(001) and Ag/Si(111), respectively using pulsed laser deposition (PLD). A series of surface probing techniques were used to characterize physical, chemical and photoemissive properties of the films.

  4. Resistive switching properties of high crystallinity and low-resistance Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3} thin film with point-contacted Ag electrodes

    SciTech Connect

    Fujimoto, Masayuki; Koyama, Hiroshi; Nishi, Yuji; Suzuki, Toshimasa

    2007-11-26

    A high-crystallinity, low-resistance Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3}(PCMO) thin film deposited by sputtering at 600 deg. C showed no resistive switching with a Pt/Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3}/Pt structure but a remarkable bipolar resistive switching with a Ag paste/Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3}/Pt structure. Observed retention fatigue of the low-resistance state was almost saturated after 24 h. The resistive switching properties were characterized as point contact of Ag grains to PCMO thin film. It was also found that the interface can form interfacial trap states and resistive change active layers. This strongly suggests that the function of the Ag point contact is similar to those of the previously proposed filament path and the nanodomain switch.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. Transport of stabilized engineered silver (Ag) nanoparticles through porous sandstones

    NASA Astrophysics Data System (ADS)

    Neukum, Christoph; Braun, Anika; Azzam, Rafig

    2014-03-01

    Engineered nanoparticles are increasingly applied in consumer products and concerns are rising regarding their risk as potential contaminants or carriers for colloid-facilitated contaminant transport. Engineered silver nanoparticles (AgNP) are among the most widely used nanomaterials in consumer products. However, their mobility in groundwater has been scarcely investigated. In this study, transport of stabilized AgNP through porous sandstones with variations in mineralogy, pore size distribution and permeability is investigated in laboratory experiments with well-defined boundary conditions. The AgNP samples were mainly characterized by asymmetric flow field-flow fractionation coupled to a multi-angle static laser light detector and ultraviolet-visible spectroscopy for determination of particle size and concentration. The rock samples are characterized by mercury porosimetry, flow experiments and solute tracer tests. Solute and AgNP breakthrough was quantified by applying numerical models considering one kinetic site model for particle transport. The transport of AgNP strongly depends on pore size distribution, mineralogy and the solution ionic strength. Blocking of attachment sites results in less reactive transport with increasing application of AgNP mass. AgNPs were retained due to physicochemical filtration and probably due to straining. The results demonstrate the restricted applicability of AgNP transport parameters determined from simplified experimental model systems to realistic environmental matrices.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Effects of surface roughness of Ag thin films on surface-enhanced Raman spectroscopy of graphene: spatial nonlocality and physisorption strain

    NASA Astrophysics Data System (ADS)

    Zhao, Yuda; Liu, Xin; Lei, Dang Yuan; Chai, Yang

    2014-01-01

    Metallic nanostructures are widely used for surface-enhanced Raman spectroscopy (SERS). Nanoscale surface corrugation significantly affects the localized plasmon response and the subsequent Raman intensity of the molecules in close proximity to the nanostructures. Experimentally, the surface roughness of metal films can be controlled by adjusting the deposition conditions, and the resulting localized near-field properties can be probed by measuring the Raman spectrum of the conformally coated monolayer graphene. The well-known Raman characteristics of graphene and its atomic-level 2D nature make it an ideal test-bed for SERS measurements on corrugated metal films. In this work, we experimentally and theoretically study the effects of surface roughness of Ag thin films on the SERS of graphene. We find that the nonlocality effect of the metal dielectric response has to be taken into account for more accurate prediction of the SERS enhancement at large surface roughness. Our results also reveal that the effect of physisorption strain should be included to understand the Raman peak shift and spectral broadening. These observations are fundamentally important for understanding the SERS from metallic nanostructures with sub-nanoscale corrugation.Metallic nanostructures are widely used for surface-enhanced Raman spectroscopy (SERS). Nanoscale surface corrugation significantly affects the localized plasmon response and the subsequent Raman intensity of the molecules in close proximity to the nanostructures. Experimentally, the surface roughness of metal films can be controlled by adjusting the deposition conditions, and the resulting localized near-field properties can be probed by measuring the Raman spectrum of the conformally coated monolayer graphene. The well-known Raman characteristics of graphene and its atomic-level 2D nature make it an ideal test-bed for SERS measurements on corrugated metal films. In this work, we experimentally and theoretically study the

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Transformation of AgCl nanoparticles in a sewer system--A field study.

    PubMed

    Kaegi, Ralf; Voegelin, Andreas; Sinnet, Brian; Zuleeg, Steffen; Siegrist, Hansruedi; Burkhardt, Michael

    2015-12-01

    Silver nanoparticles (Ag-NP) are increasingly used in consumer products and their release during the use phase may negatively affect aquatic ecosystems. Research efforts, so far, have mainly addressed the application and use of metallic Ag(0)-NP. However, as shown by recent studies on the release of Ag from textiles, other forms of Ag, especially silver chloride (AgCl), are released in much larger quantities than metallic Ag(0). In this field study, we report the release of AgCl-NP from a point source (industrial laundry that applied AgCl-NP during a piloting phase over a period of several months to protect textiles from bacterial regrowth) to the public sewer system and investigate the transformation of Ag during its transport in the sewer system and in the municipal wastewater treatment plant (WWTP). During the study period, the laundry discharged ~85 g of Ag per day, which dominated the Ag loads in the sewer system from the respective catchment (72-95%) and the Ag in the digested WWTP sludge (67%). Combined results from electron microscopy and X-ray absorption spectroscopy revealed that the Ag discharged from the laundry to the sewer consisted of about one third AgCl and two thirds Ag2S, both forms primarily occurring as nanoparticles with diameters<100 nm. During the 800 m transport in the sewer channel to the nearby WWTP, corresponding to a travel time of ~30 min, the remaining AgCl was transformed into nanoparticulate Ag2S. Ag2S-NP also dominated the Ag speciation in the digested sludge. In line with results from earlier studies, the very low Ag concentrations measured in the effluent of the WWTP (<0.5 μg L(-1)) confirmed the very high removal efficiency of Ag from the wastewater stream (>95%). PMID:25582606

  4. 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

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

    DOE PAGESBeta

    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

  6. Definiteness, Animacy, and NP Ordering.

    ERIC Educational Resources Information Center

    Ransom, Evelyn N.

    The constraints in English on the definiteness, specificity, humaness and animacy of noun phrases (NP's) undergoing passive and dative movement are examined. Evidence presented shows that these constraints occur in other languages in marked and unmarked constructions as absolute constraints on acceptability or as tendencies. This suggests a…

  7. [Two types of NP-NP associations in influenza virus-infected cells].

    PubMed

    Semenova, N P; Chumakov, V M; Grigor'eva, T A; Rudneva, I A; Burov, V V; Prokudina, E N

    2007-01-01

    Two types of NP-NP associations are shown to form in the influenza virus-infected cells. Early NP synthesis gives rise to NP associations stabilized by relatively weak bonds. These structures are designed as NP multimers. The high protease- and heat-sensitivities allow NP-multimers to be regarded as incompletely folded proteins. Post-translationally, NP-multimers transform to compact NP associations (NP oligomers) that are relatively highly heat-and protease-resistant. The NP-multimers untransformed to the folded compact NP-oligomers accumulate in the cells and partially degraded. Whether both types of NP-NP associations may be of significance is under discussion. PMID:17601043

  8. 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.

  9. Reliable determination of 237Np in environmental solid samples using 242Pu as a potential tracer.

    PubMed

    Qiao, Jixin; Hou, Xiaolin; Roos, Per; Miró, Manuel

    2011-04-15

    This paper reports an analytical method for rapid determination of neptunium ((237)Np) in environmental solid samples exploiting automated sequential injection (SI)-based anion exchange separation. Pivotal issues on analytical method performance were investigated including sorption behavior of (237)Np onto various AG 1-type anion exchangers; suitability of (242)Pu as a tracer for (237)Np determination in environmental solid samples; and long-term chemical stability of tetravalent Np. Experimental results revealed that the degree of resin cross-linking has a significant influence on the separation efficiency in terms of chemical yields of (237)Np and removal of interfering nuclides. Although ca. 30% of sorbed Np onto AG 1- × 4 was stripped out during HCl rinsing step for the removal of Th, chemical yield ratios of (237)Np to (242)Pu were proven steady with an average value of 0.67 ± 0.04 (n=15) under selected experimental conditions. Disulfite-8M HNO(3) was selected as a redox pair for valence adjustment to Np(IV) and the tetravalent Np in the sample solution was demonstrated to be stabilized for up to 5 days under 3°C. The analytical results for reference materials showed a good agreement with the expected values, thereby demonstrating the usefulness of (242)Pu as a non-isotopic tracer for (237)Np chemical yield monitoring. The on-column separation procedure fosters rapid analysis as required in emergency situations since each individual sample can be handled within 2.5h, and leads to a significant decrease in labor intensity compared to conventional batch-wise protocols. PMID:21376978

  10. Interfacial structure in thin water layers formed by forced dewetting on self-assembled monolayers of omega-terminated alkanethiols on Ag.

    PubMed

    Tiani, Domenic J; Yoo, Heemin; Mudalige, Anoma; Pemberton, Jeanne E

    2008-12-01

    A method for the spectroscopic characterization of interfacial fluid molecular structure near solid substrates is reported. The thickness and interfacial molecular structure of residual ultrathin D20 films remaining after forced dewetting on alkanethiolate self-assembled monolayers (SAMs) of 11 1-mercaptoundecanoic acid (11-MUA), 11-mercaptoundecanol (11-MUD), and undecanethiol (UDT) on Ag are investigated using ellipsometry and surface Raman spectroscopy. The residual film thickness left after withdrawal is greater on hydrophilic SAMs than on hydrophobic SAMs. This behavior is rationalized on the basis of differing degrees of fluid slip within the interfacial region due to different interfacial molecular structure. The v(O-D) regions of surface Raman spectra clearly indicate unique interfacial molecular properties within these films that differ from bulk D20. Although the residual films are created by shear forces and Marangoni flow at the three-phase line during the forced dewetting process, the nature of the films sampled optically must also be considered from the standpoint of thin film stability after dewetting. Thus, the resulting D20 films exist in vastly different morphologies depending on the nature of the water-SAM interactions. Residual D20 is proposed to exist as small nanodroplets on UDT surfaces due tospontaneous rupture of the film after dewetting. In contrast, on 11-MUD and 11-MUA surfaces, these films exist in a metastable state that retains their conformal nature on the underlying modified surface. Analysis of the peak intensity ratios of the so-called "ice-like" to "liquid-like" v(O-D) modes suggests more ice-like D20 character near 11-MUD surfaces, but more liquid-like character near 11-MUA and UDT surfaces. The creation of residual ultrathin films by forced dewetting is thus demonstrated to be a powerful method for characterizing interfacial molecular structure of fluids near a solid substrate under ambient conditions of temperature and

  11. The novel transparent sputtered p-type CuO thin films and Ag/p-CuO/n-Si Schottky diode applications

    NASA Astrophysics Data System (ADS)

    Tombak, A.; Benhaliliba, M.; Ocak, Y. S.; Kiliçoglu, T.

    In the current paper, the physical properties and microelectronic parameters of direct current (DC) sputtered p-type CuO film and diode have been investigated. The film of CuO as oxide and p-type semiconductor is grown onto glass and n-Si substrates by reactive DC sputtering at 250 °C. After deposition, a post-annealing procedure is applied at various temperatures in ambient. Through this research, several parameters are determined such structural, optical and electrical magnitudes. The thickness of CuO thin films goes from 122 to 254 nm. A (1 1 1)-oriented cubic crystal structure is revealed by X-ray analysis. The grain size is roughly depending on the post-annealing temperature, it increases with temperature within the 144-285 nm range. The transmittance reaches 80% simultaneously in visible and infrared bands. The optical band gap is varied between 1.99 and 2.52 eV as a result of annealing temperature while the resistivity and the charge carrier mobility decrease with an increase in temperature from 135 to 14 Ω cm and 0.92 to 0.06 cm2/Vs, respectively. The surface of samples is homogenous, bright dots are visible when temperature reaches the highest value. As a diode, Ag/CuO/n-Si exhibits a non-ideal behavior and the ideality factor is about 3.5. By Norde method, the barrier height and the series resistance are extracted and found to be 0.96 V and 86.6 Ω respectively.

  12. 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

  13. The concentration-dependent aggregation of Ag NPs induced by cystine.

    PubMed

    Afshinnia, K; Gibson, I; Merrifield, R; Baalousha, M

    2016-07-01

    Cystine is widely used in cell culture media. Cysteine, the reduced form of cystine, is widely used to scavenge dissolved Ag in eco-toxicological studies to differentiate dissolved vs. nanoparticle uptake and toxicity. However, little is known about the impact of cysteine and cystine on the aggregation behavior of Ag NPs, in particular as a function of Ag NP concentration. Herein, we investigate how cystine (0-300μM) affects the stability of citrate-, polyvinylpyrrolidone-, and polyethylene glycol-coated silver nanoparticles (cit-Ag NPs, PVP-Ag NPs and PEG-Ag NPs, respectively) with and without Suwannee River fulvic acid (SRFA) as a function of Ag NPs concentration using UV-vis spectroscopy at environmentally and ecotoxicologically relevant Ag NP concentrations (ca. 125-1000μgL(-1)). The results demonstrate, for the first time, the concentration-dependent aggregation of cit-Ag NPs in the presence of cystine with a shift in the critical coagulation concentration (CCC) to lower cystine concentrations at lower cit-Ag NP concentrations. At the highest cit-Ag NP concentration (1000μgL(-1)), reaction limited aggregation was only observed and no CCC was measured. SRFA slowed the aggregation of cit-Ag NPs by cystine and aggregation occurred in reaction limited aggregation (RLA) regime only. No CCC value was measured in the presence of SRFA. Cystine replaces citrate, PVP and PEG coatings, resulting in aggregation of both electrostatically and sterically stabilized Ag NPs. These findings are important in understanding the factors determining the behavior of Ag NPs in cell culture media. Also due to the similarity between cystine and cysteine, these results are important in understanding the uptake and toxicity of Ag NPs vs. Ag ions, and suggest that the reduction of the toxicity of Ag NPs in the presence of cysteine could be due to a combined effect of scavenging Ag(+) ions and Ag NP aggregation in the presence of cysteine. PMID:27016687

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Enhancement of magneto-optical Kerr effect for Co ultra-thin film on Pt(1 1 1) with Ag buffer layer

    NASA Astrophysics Data System (ADS)

    Ho, H. Y.; Tzeng, C. L.; Su, C. W.; Shern, C. S.

    2004-11-01

    The magnetic properties of Co/1 ML Ag/Pt(1 1 1) have been monitored by magneto-optical Kerr effect. We find that the magnetization easy axis changes its direction from the out-of-plane to the in-plane when dCo⩾2 ML. In the annealing studies of 1 ML Co/1 ML Ag/Pt(1 1 1), the result shows that the enhancement in perpendicular magnetic anisotropy is strongly related to the formation of Co-Pt alloy. The atomic exchange between Co and Ag cause the increase of the coercivity. The possible mechanisms of the enhancement in perpendicular magnetic anisotropy and coercivity are discussed.

  19. 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…

  20. 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

  1. Controlled preparation of Ag nanoparticle films by a modified photocatalytic method on TiO2 films with Ag seeds for surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Fu, Xin; Pan, Lujun; Li, Shuai; Wang, Qiao; Qin, Jun; Huang, Yingying

    2016-02-01

    Uniform Ag nanoparticle (NP) films were synthesized by a modified photocatalytic method on TiO2 films with Ag seeds for surface-enhanced Raman scattering, which combine the advantages of the spurting method (high nucleation density) and the traditional photocatalytic method (suitable particle size). The Ag seeds were prepared by magnetron sputtering with different time, which would adjust the distribution and transfer of electrons on the surface of TiO2 film in the process of photocatalytic reduction. The distribution and morphology of Ag NP films can be adjusted by the sputtering time and the UV irradiation time. The Raman enhancement of as-prepared Ag NP films was calculated by finite-difference time-domain to validate the experiment data. It is found that the Ag NP films synthesized on TiO2 films with suitable pre-deposited Ag seeds exhibit a much higher Raman enhancement activity than the optimum Ag NP film synthesized directly on the TiO2 film without Ag seeds.

  2. 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. PMID:22516207

  3. SiO2/TiO2/n-Si/Ag(Cr)/TiO2 thin films with superhydrophilicity and low-emissivity

    NASA Astrophysics Data System (ADS)

    Loka, Chadrasekhar; Ryeol Park, Kyoung; Lee, Kee-Sun

    2016-01-01

    In this study, SiO2/TiO2/n-Si/Ag(Cr)/TiO2 multilayer structures have been designed and deposited by the RF and DC magnetron sputtering at room temperature. The as-deposited TiO2/glass films which are initially amorphous in nature were subjected to post annealing at 673 K for anatase phase TiO2. The anatase TiO2 films showed an optical bandgap ˜3.32 eV. The Ag(Cr)/TiO2 showed very low-emissivity (low-e) value ˜0.081 which is evaluated by using the sheet resistance (6.51 Ω/□) of the films. All the deposited films showed high visible transmittance (˜81%) and high infrared reflectance (72%) which are recorded by using the UV-vis-NIR spectrophotometer. In addition, experimentally obtained optical properties were in good agreement with the simulation data. The TiO2/n-Si heterojunction concept has been employed to enhance the superhydrophilicity of the deposited multilayer stack, TiO2/n-Si/Ag(Cr)/TiO2 films exhibited best superhydrophilicity with water contact angle ˜2°. The deposited multilayer structures SiO2/TiO2/n-Si/Ag(Cr)/TiO2 and TiO2/n-Si/Ag(Cr)/TiO2 achieved significant low-e and superhydrophilicity.

  4. 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).

  5. (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. PMID:24675054

  6. Mediator and label free estimation of stress biomarker using electrophoretically deposited Ag@AgO-polyaniline hybrid nanocomposite.

    PubMed

    Kaushik, Ajeet; Vasudev, Abhay; Arya, Sunil K; Bhansali, Shekhar

    2013-12-15

    Cortisol, a steroid hormone, is an important biomarker for psychological stress and its detection is gaining prominence for personalized health monitoring. In present work, electrophoretically deposited nanocomposite films of polyaniline (PANI) and core-shell Ag@AgO nanoparticles (NP~5 nm) have been explored as an electro-active nanostructured platform for Anti-cortisol antibody (Anti-Cab) immobilization for electrochemical immunosensing of cortisol. Covalent binding of Anti-Cab onto Ag@AgO-PANI nanocomposite was achieved using EDC/NHS chemistry, which results in the amide bond formation between amino groups of PANI and COOH groups of anti-Cab. Nonspecific binding sites on the immunosensing electrodes were blocked using bovine serum albumin (BSA). The uniform distribution of electro-active and surface charged Ag@AgO NP in PANI matrix results in a nanoporous granular morphology (roughness~10 nm) that provides a functionalized conductive microenvironment for Anti-Cab immobilization. The BSA/Anti-Cab/Ag@AgO-PANI/Au bioelectrodes have been characterized using electrochemical impedance technique (EIS), cyclic voltammetric (CV) technique and atomic force microscopic (AFM) technique, respectively. In CV studies nanocomposite exhibited characteristic response current peak corresponding to AgO NP (0.25 V) with large magnitude of current response and resulted in high electron transport at the electrode-electrolyte interface without a mediator. Electrochemical response studies via CV for the fabricated BSA/Anti-Cab/Ag@AgO-PANI/Au immunosensor as a function of cortisol concentration exhibited a wide linear detection range of 1 pM-1 µM, a detection limit of 0.64 pM mL(-1)(lower than ELISA), and high sensitivity 66 µA M(-1) with a regression coefficient of 0.998. The findings of present work may explore the application of Ag@AgO-PANI hybrid nanocomposite to detect cortisol and other biomarkers for point-of-care application. PMID:23831854

  7. 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.

  8. 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.

  9. Pulsed Laser Deposition and Reflection High-Energy Electron Diffraction studies of epitaxial long range order, nano- and microstructured Ag thin films grown on MgO, Al2 O3 , STO and Si

    NASA Astrophysics Data System (ADS)

    Velazquez, Daniel; Seibert, Rachel; Man, Hamdi; Spentzouris, Linda; Terry, Jeff

    2015-03-01

    Pulsed Laser Deposition is a state-of-the-art technique that allows for the fine tunability of the deposition rate, highly uniform and epitaxial sample growth, the ability to introduce partial pressures of gases into the experimental chamber for growth of complex materials without interfering with the energy source (laser). An auxiliary in situ technique for growth monitoring, Reflection High-Energy Electron Diffraction, is a powerful characterization tool for predictability of the surface physical structure both, qualitatively and quantitatively. RHEED patterns during and post deposition of Ag thin films on MgO, Al2O3, Si and STO substrtates are presented and their interpretations are compared with surface imaging techniques (SEM, STM) to evidence the usefulness of the technique.

  10. Standardization of ²³⁷Np.

    PubMed

    Laureano-Perez, Lizbeth; Fitzgerald, R; Collé, R

    2014-05-01

    The standardization of (237)Np was investigated. The certified massic activity for (237)Np was obtained by 4παβ liquid scintillation (LS) counting with correction for the (233)Pa daughter using the CIEMAT/NIST efficiency tracing method using a (3)H standard. Confirmatory measurements were also performed by high-resolution HPGe gamma-ray spectrometry, and by 4παβ(LS)-γ(NaI) anticoincidence counting. All results agree within the respective method's uncertainties. It was confirmed that the (237)Np/(233)Pa radioactive equilibrium is disturbed when making dilutions and/or removing aliquots. PMID:24378363

  11. 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

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

    PubMed

    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

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. A highly conserved region of the Sendai virus nucleocapsid protein contributes to the NP-NP binding domain.

    PubMed

    Myers, T M; Pieters, A; Moyer, S A

    1997-03-17

    The nucleocapsid protein (NP) of Sendai virus is an essential component of both the nucleocapsid template and the NP-NP and NP0-P protein complexes required for viral RNA replication. When expressed alone in mammalian cells NP self-assembles into nucleocapsid-like particles which appear to contain cellular RNA. To identify putative NP-NP binding domains, fusions between the monomeric maltose-binding protein (MBP) and portions of NP were constructed. The fusion proteins which contain the central conserved region (CCR) (amino acids 258-357, MBP-NP1) and the N-terminal 255 amino acids (MBP-NP2) of NP both oligomerized, suggesting that these regions contain sequences important for NP-NP self-assembly. In addition, the MBP-NP1 fusion protein can function as an inhibitor of viral RNA replication. Complementary studies involving site-directed mutagenesis of the full-length NP protein have identified specific residues in the CCR which are essential for viral RNA replication in vitro. Two such replication-negative mutants, F324V and F324I, were defective in self-assembly, suggesting that the Phe residue at amino acid 324 is essential for the NP-NP interaction. A third mutant, NP260-1 (Y260D), self-assembled to form aberrant oligomers which exhibit an unusual helical structure and appear to lack any associated RNA. The mutants NP299-5 (L299I and I300V) and NP313-2 (I313F), in contrast, appear to form all the required protein complexes, but were inactive in viral RNA replication, suggesting that interactions specifically with Sendai RNA were disrupted. These data have thus identified specific residues in the CCR of the native NP protein which appear to be important for NP-NP or NP-RNA interactions and for genome replication. PMID:9126246

  18. Fabrication and characterization of AgI/Ag hollow fibers for near-infrared lasers

    NASA Astrophysics Data System (ADS)

    Zeng, Xuan; Liu, Bing-Hong; He, Yu-Jing; Sun, Bang-Shan; Iwai, Katsumasa; Miyagi, Mitsunobu; Shi, Yi-Wei

    2013-07-01

    AgI/Ag hollow fibers have found applications in mid- and far-infrared regions owing to the properties of low loss and high power capability. It has been a challenge to fabricate low-loss AgI/Ag hollow fiber in the near-infrared laser light. In this paper, we report on improvements of the fabrication technology. In order to coat a thin and smooth AgI film, ethanol was used as the solvent of iodine and the iodination process is carried out in low temperatures with high flow-rate of iodine solution. Low-loss AgI/Ag hollow fibers with various inner diameters were firstly obtained for 1 μm wavelength band. Fabrication parameters were discussed in detail and transmission properties were characterized.

  19. Studies on electronic structure of interfaces between Ag and gelatin for stabilization of Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Tani, Tadaaki; Uchida, Takayuki

    2015-06-01

    Extremely high stability of Ag nanoparticles in photographic materials has forced us to study the electronic structures of the interfaces between thin layers of Ag, Au, and Pt and their surface membranes in ambient atmosphere by photoelectron yield spectroscopy in air and Kelvin probe method. Owing to the Fermi level equalization between a metal layer and a membrane coming from air, the electron transfer took place from the membrane to Pt and Au layers and from an Ag layer to the membrane, giving the reason for poor stability of Ag nanoparticles in air. The control of the Fermi level of an Ag layer with respect to that of a gelatin membrane in air could be widely made according to Nernst’s equation by changing the pH and pAg values of an aqueous gelatin solution used to form the membrane, and thus available to stabilize Ag nanoparticles in a gelatin matrix.

  20. 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.

  1. 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

  2. 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

  3. Extracellular polymeric substances (EPS) of freshwater biofilms stabilize and modify CeO2 and Ag nanoparticles.

    PubMed

    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

  4. 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.

  5. 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

  6. Alumina supported model Pd Ag catalysts: A combined STM, XPS, TPD and IRAS study

    NASA Astrophysics Data System (ADS)

    Khan, N. A.; Uhl, A.; Shaikhutdinov, S.; Freund, H.-J.

    2006-05-01

    The bimetallic Pd-Ag model catalysts were prepared by physical vapor deposition on thin alumina films. The morphology and structure of the Pd-Ag particles were studied by STM, XPS, and by TPD and IRAS of CO. The results showed the formation of true alloy particles with Ag segregated at the surface. The addition of Ag first suppresses the most strongly bonded CO on threefold hollow sites of Pd. With further increasing Ag coverage, only isolated Pd atoms surrounded by Ag atoms are likely present on the surface. The results on CO adsorption suggest that the model Pd-Ag system mimics the structure of the real Pd-Ag catalysts.

  7. 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.

  8. 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. PMID:25912640

  9. 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.

  10. VACTERL with the mitochondrial np 3243 point mutation.

    PubMed

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

    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 yet 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. PMID:8723071

  11. 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.

  12. 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

  13. Theorem proposed regarding P-NP problem

    NASA Astrophysics Data System (ADS)

    Wang, Jie

    1986-09-01

    Baker, et al,. were the first to use relativization studies on the problem P = ?NP, which obtained penetrating results. The necessary and sufficient conditions are discussed where for an arbitrary language B there is an existing language A that allows P sup A = PN sup B.

  14. 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.

  15. Magnetocaloric effect and temperature coefficient of resistance of La0.85Ag0.15MnO3 epitaxial thin films obtained by polymer-assisted deposition

    NASA Astrophysics Data System (ADS)

    Cobas Acosta, R.; Muñoz-Pérez, S.; Cadogan, J. M.; Hutchison, W. D.; Ridgway, M. C.

    2014-07-01

    We report the magnetocaloric effects and temperature coefficient of resistance (TCR) of La0.85Ag0.15MnO3 epitaxial thin films grown on single-crystal substrates of LaAlO3 (001) and SrTiO3 (001) using the chemical solution approach of polymer-assisted deposition (PAD). The film thicknesses are in the range 30-35 nm. Magnetocaloric effects, with entropy changes of -2.14 J/kg.K, in the case of the LaAlO3 substrate and -2.72 J/kg.K for the SrTiO3 substrate, (corresponding to a magnetic field variation of 2T) were obtained at room temperature. The refrigeration capacity at this field variation reached large values of 125 J/kg and 216 J/kg, indicating that these films prepared by PAD have the potential for microcooling applications. The temperature coefficient of resistance has been calculated from the resistivity measurements. A maximum TCR value of 3.01 % K-1 was obtained at 309 K, which shows that these films also have potential as uncooled thermometers for bolometric applications.

  16. Agglomeration of Ag and TiO2 nanoparticles in surface and wastewater: Role of calcium ions and of organic carbon fractions.

    PubMed

    Topuz, Emel; Traber, Jacqueline; Sigg, Laura; Talinli, Ilhan

    2015-09-01

    This study aims to investigate factors leading to agglomeration of citrate coated silver (AgNP-Cit), polyvinylpyrrolidone coated AgNPPVP and titanium dioxide (TiO2) nanoparticles in surface waters and wastewater. ENPs (1 mg/L) were spiked to unfiltered, filtered, ultrafiltered (<10 kDa and <1 kDa) samples. Z-average particle sizes were measured after 1 h, 1 day and 1 week. AgNP-PVP was stable in all fractions of the samples and kept their original size around 60 nm over 1 week. Agglomeration of AgNP-Cit and TiO2 was positively correlated with Ca(2+) concentration, but dissolved organic carbon concentrations > 2 mg/L contributed to stabilizing these NP. Moreover, agglomeration of AgNP-Cit in the various organic matter fractions showed that high molecular weight organic compounds such as biopolymers provide stabilization in natural water. A generalized scheme for the agglomeration behavior of AgNP-Cit, AgNP-PVP and TiO2 in natural waters was proposed based on their relation with Ca(2+), Mg(2+) and DOC concentration. PMID:26057362

  17. Laser stimulated electrooptics in the Ag-ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Tan, Sin Tee; AlZayed, N. S.; Lakshminarayana, G.; Naumar, F.; Umar, A. A.; Oyama, M.; Myronchuk, G.; Kityk, I. V.

    2014-07-01

    In the present work, we have discovered a photoinduced linear electrooptics in ZnO nanorods which were fabricated by simply varying the content of the growth solution. It was established that by varying the growth solution concentration one can vary the surface density of the ZnO nanorod arrays growth on the surface. The lowest ZnO content produces the lowest surface density in the nanorods. The photoinduced linear electrooptics was studied using the He-Ne laser at wavelength 1150 nm and was stimulated by 7 ns nitrogen laser at 371 nm. The nonlinear dependence of the Ag nanoparticle (NP) concentration was found and it was significantly higher than that for the pure ZnO NP. Principal role of the Ag NP on the observed effects was discussed.

  18. 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.

  19. 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.

  20. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    NASA Astrophysics Data System (ADS)

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-09-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested.

  1. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    PubMed Central

    2014-01-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested. PMID:25258607

  2. 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

  3. 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.

  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. PMID:26699450

  5. 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.

  6. 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.

  7. 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.

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

    DOE PAGESBeta

    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

  9. 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.

  10. Industrial sludge remediation with photonic treatment using Ti-Ag nano-composite thin films: persistent organic pollutant removal from sludge matrix.

    PubMed

    Tunçal, Tolga; Uslu, Orhan

    2015-02-01

    Mechanically dewatered industrial sludge (MDIS) was treated using pure and silver-doped thin films (TFs) grown on quartz substrates. TFs were prepared using a sol-gel dip coating technique. The resulting films were annealed at 450 °C for 3 h and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Mixtures that were homogeneous in the UV A (380 nm) and UVvis (450 nm) regions of the electromagnetic spectrum were used as the irradiation source. The results revealed that illumination with different wavelengths helps to generate well-separated e(-)/h(+) pairs, resulting in a decrease in the recombination rate. An electron transfer chain model was also developed using the experimental results. The performance of the applied method was evaluated by observing variations in the sludge bound water content (SBWC), volatile solids removal rate (VSR), and the consumed and generated energy fluxes through endergonic and exergonic reactions. After treatment, SBWC was reduced from 65% ± 1% to 39% ± 1 and the highest VSR was measured to be 27 ± 0.1 mg VSS cm(-2) h(-1). The consumed and recovered energy fluxes were 960 ± 151 and 412 ± 26 J g(-1) VS(removed), respectively. Raw sludge and polychlorinated biphenyls (∑(15)PCB) and polyaromatic hydrocarbon (∑(16)PAH) concentrations were 4356.82 ± 22 μg kg(-1) and 446.25 ± 4.8 μg kg(-1), respectively. The ∑(15)PCB and ∑(16)PAH concentrations in the treated sludge samples were 129.86 ± 22 μg kg(-1) and 34.85 ± 1.3 μg kg(-1), respectively. PMID:25463569

  11. 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

  12. thin films as absorber

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    Photovoltaic structures were prepared using AgSb(S x Se1- x )2 as absorber and CdS as window layer at various conditions via a hybrid technique of chemical bath deposition and thermal evaporation followed by heat treatments. Silver antimony sulfo selenide thin films [AgSb(S x Se1- x )2] were prepared by heating multilayers of sequentially deposited Sb2S3/Ag dipped in Na2SeSO3 solution, glass/Sb2S3/Ag/Se. For this, Sb2S3 thin films were deposited from a chemical bath containing SbCl3 and Na2S2O3. Then, Ag thin films were thermally evaporated on glass/Sb2S3, followed by selenization by dipping in an acidic solution of Na2SeSO3. The duration of dipping was varied as 3, 4 and 5 h. Two different heat treatments, one at 350 °C for 20 min in vacuum followed by a post-heat treatment at 325 °C for 2 h in Ar, and the other at 350 °C for 1 h in Ar, were applied to the multilayers of different configurations. X-ray diffraction results showed the formation of AgSb(S x Se1- x )2 thin films as the primary phase and AgSb(S,Se)2 and Sb2S3 as secondary phases. Morphology and elemental detection were done by scanning electron microscopy and energy dispersive X-ray analysis. X-ray photoelectron spectroscopic studies showed the depthwise composition of the films. Optical properties were determined by UV-vis-IR transmittance and reflection spectral analysis. AgSb(S x Se1- x )2 formed at different conditions was incorporated in PV structures glass/FTO/CdS/AgSb(S x Se1- x )2/C/Ag. Chemically deposited post-annealed CdS thin films of various thicknesses were used as window layer. J- V characteristics of the cells were measured under dark and AM1.5 illumination. Analysis of the J- V characteristics resulted in the best solar cell parameters of V oc = 520 mV, J sc = 9.70 mA cm-2, FF = 0.50 and η = 2.7 %.

  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. 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

  15. 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+.

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

    PubMed

    Kovács, Attila; Infante, Ivan

    2015-08-21

    The electronic spectra of neutral NpO and NpO2 as well as of their mono- (NpO(+), NpO2(+)) and dications (NpO(2+), NpO2(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(-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 NpO2(2+). PMID:26298132

  17. 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

  18. Anomalous photoelectric emission from Ag on zinc-phthalocyanine film

    NASA Astrophysics Data System (ADS)

    Tanaka, Senku; Otani, Tomohiro; Fukuzawa, Ken; Ogawa, Koji; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao; Hiromitsu, Ichiro

    2014-05-01

    Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4 eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4 eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1 nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles.

  19. Anomalous photoelectric emission from Ag on zinc-phthalocyanine film

    SciTech Connect

    Tanaka, Senku; Otani, Tomohiro; Fukuzawa, Ken; Hiromitsu, Ichiro; Ogawa, Koji; Azuma, Junpei; Yamamoto, Isamu; Takahashi, Kazutoshi; Kamada, Masao

    2014-05-12

    Photoelectric emission from organic and metal thin films is generally observed with irradiation of photon energy larger than 4 eV. In this paper, however, we report photoelectric emission from Ag on a zinc-phthalocyanine (ZnPc) layer at a photon energy of 3.4 eV. The threshold energy for this photoelectric emission is much smaller than the work function of Ag estimated by conventional photoelectron spectroscopy. The photoelectric emission by low-energy photons is significant for Ag thicknesses of less than 1 nm. Photoelectron spectroscopy and morphological study of the Ag/ZnPc suggest that the anomalous photoelectric emission from the Ag surface is caused by a vacuum level shift at the Ag/ZnPc interface and by surface plasmons of the Ag nanoparticles.

  20. 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%.

  1. 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.

  2. 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.%.

  3. 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.

  4. Characteristics of localized surface plasmons excited on mixed monolayers composed of self-assembled Ag and Au nanoparticles.

    PubMed

    Tanaka, Daisuke; Imazu, Keisuke; Sung, Jinwoo; Park, Cheolmin; Okamoto, Koichi; Tamada, Kaoru

    2015-10-01

    The fundamental characteristics of localized surface plasmon resonance (LSPR) excited on mixed monolayers composed of self-assembled Ag and Au nanoparticles (AgNPs and AuNPs, respectively) were investigated. Mixed monolayered films were fabricated at the air-water interface at different mixing ratios. The films retained their phase-segregated morphologies in which AuNPs formed several 10 to 100 nm island domains in a homogeneous AgNP matrix phase. The LSPR bands originating from the self-assembled domains shifted to longer wavelengths as the domain size increased, as predicted by a finite-difference time-domain (FDTD) simulation. The FDTD simulation also revealed that even an alternating-lattice-structured two-dimensional (2D) AgNP/AuNP film retained two isolated LSPR bands, revealing that the plasmon resonances excited on each particle did not couple even in a continuous 2D sheet, unlike in the homologous NP system. The fluorescence quenching test of Cy3 and Cy5 dyes confirmed that the independent functions of AuNPs and AgNPs remained in the mixed films, whereas the AuNPs exhibited significantly higher quenching efficiency for the Cy3 dye compared with AgNPs due to the overlap of the excitation/emission bands of the dyes with the AuNP LSPR band. Various applications can be considered using this nanoheterostructured plasmonic assembly to excite spatially designed, high-density LSPR on macroscopic surfaces. PMID:26332039

  5. Parallel nano-assembling of a multifunctional GO/HapNP coating on ultrahigh-purity magnesium for biodegradable implants

    NASA Astrophysics Data System (ADS)

    Santos, C.; Piedade, C.; Uggowitzer, P. J.; Montemor, M. F.; Carmezim, M. J.

    2015-08-01

    This work reports the one-step fabrication of a novel coating on ultra high purity magnesium using a parallel nano assembling process. The multifunctional biodegradable surface was obtained by adding hydroxyapatite nanoparticles (HapNP) plus graphene oxide (GO). The coating was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), micro-Raman spectroscopy. The thin phosphate coating (thickness of 1 μm) reveals a uniform coverage with cypress like structures. The incorporation of HapNP and GO promotes the hydrophilic behavior of the coating surface. The results revealed that the proposed coating can be used to tailor the surface properties such as wettability by adjusting the contents of HapNP and GO. The in vitro degradation rate of the coated magnesium suggests that the presence of HapNP and GO/HapNP in the phosphate coating decreased the current density compared to the single phosphate coating and uncoated magnesium. This study also reveals the HapNP/GO/phosphate coating induces apatite formation, showing suitable degradability that makes it a promising coating candidate for enhanced bone regeneration.

  6. 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).

  7. 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

  8. 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.

  9. 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. PMID:26726525

  10. Mildly reduced graphene oxide-Ag nanoparticle hybrid films for surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Li, Xiaocheng; Tay, Beng Kang; Li, Junshuai; Tan, Dunlin; Tan, Chong Wei; Liang, Kun

    2012-04-01

    Large-area mildly reduced graphene oxide (MR-GO) monolayer films were self-assembled on SiO2/Si surfaces via an amidation reaction strategy. With the MR-GO as templates, MR-GO-Ag nanoparticle (MR-GO-Ag NP) hybrid films were synthesized by immersing the MR-GO monolayer into a silver salt solution with sodium citrate as a reducing agent under UV illumination. SEM image indicated that Ag NPs with small interparticle gap are uniformly distributed on the MR-GO monolayer. Raman spectra demonstrated that the MR-GO monolayer beneath the Ag NPs can effectively quench the fluorescence signal emitted from the Ag films and dye molecules under laser excitation, resulting in a chemical enhancement (CM). The Ag NPs with narrow gap provided numerous hot spots, which are closely related with electromagnetic mechanism (EM), and were believed to remarkably enhance the Raman signal of the molecules. Due to the co-contribution of the CM and EM effects as well as the coordination mechanism between the MR-GO and Ag NPs, the MR-GO-Ag NP hybrid films showed more excellent Raman signal enhancement performance than that of either Ag films or MR-GO monolayer alone. This will further enrich the application of surface-enhanced Raman scattering in molecule detection.

  11. Photochemical synthesis of Ag nanobars and their potential application as catalyst

    NASA Astrophysics Data System (ADS)

    Pyne, Santanu; Samanta, Sadhan; Misra, Ajay

    2013-12-01

    Monodispersed sodium alginate (SA) stabilized silver nano bar and hydroxyl propyl methyl cellulose (HPMC) stabilized silver nano bar have been synthesized by photochemical method. The nanoparticles are characterized by UV-VIS-NIR spectroscopy, transmission electron microscopy (TEM) and selected area electron diffraction (SAED) study. Catalytic reduction of 4-nitrophenol (4-NP) by sodium borohydride in presence of nanoparticles is also evaluated. The kinetic data obtained by monitoring the change in UV-Vis absorption spectra of 4-NP are explained by Langmuir-Hinshelwood model. It is observed that the rate of reduction is higher in SA stabilized Ag nano bar than the HPMC stabilized Ag nano bar.

  12. Antibacterial performance of Ag nanoparticles and AgGO nanocomposites prepared via rapid microwave-assisted synthesis method

    NASA Astrophysics Data System (ADS)

    Chook, Soon Wei; Chia, Chin Hua; Zakaria, Sarani; Ayob, Mohd Khan; Chee, Kah Leong; Huang, Nay Ming; Neoh, Hui Min; Lim, Hong Ngee; Jamal, Rahman; Rahman, Raha Mohd Fadhil Raja Abdul

    2012-09-01

    Silver nanoparticles and silver-graphene oxide nanocomposites were fabricated using a rapid and green microwave irradiation synthesis method. Silver nanoparticles with narrow size distribution were formed under microwave irradiation for both samples. The silver nanoparticles were distributed randomly on the surface of graphene oxide. The Fourier transform infrared and thermogravimetry analysis results showed that the graphene oxide for the AgNP-graphene oxide (AgGO) sample was partially reduced during the in situ synthesis of silver nanoparticles. Both silver nanoparticles and AgGO nanocomposites exhibited stronger antibacterial properties against Gram-negative bacteria ( Salmonella typhi and Escherichia coli) than against Gram-positive bacteria ( Staphyloccocus aureus and Staphyloccocus epidermidis). The AgGO nanocomposites consisting of approximately 40 wt.% silver can achieve antibacterial performance comparable to that of neat silver nanoparticles.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Heat-induced spinodal decomposition of Ag-Cu nanoparticles.

    PubMed

    Sopoušek, Jiří; Zobač, Ondřej; Buršík, Jiří; Roupcová, Pavla; Vykoukal, Vít; Brož, Pavel; Pinkas, Jiří; Vřešt'ál, Jan

    2015-11-14

    Solvothermal synthesis was used for Ag-Cu nanoparticle (NP) preparation from metallo-organic precursors. The detailed NP characterization was performed to obtain information about nanoparticle microstructure and both phase and chemical compositions. The resulting nanoparticles exhibited chemical composition inside a FCC_Ag + FCC_Cu two-phase region. The microstructure study was performed by various methods of electron microscopy including high-resolution transmission electron microscopy (HRTEM) at an atomic scale. The HRTEM and X-ray diffraction studies showed that the prepared nanoparticles form the face centred cubic (FCC) crystal lattice where the silver atoms are randomly mixed with copper. The CALPHAD approach was used for predicting the phase diagram of the Ag-Cu system in both macro- and nano-scales. The predicted spinodal decomposition of the metastable Ag-Cu nanoparticles was experimentally induced by heating on an X-ray powder diffractometer (HT XRD). The nucleation of the Cu-rich phase was detected and its growth was studied. Changes in the Ag-rich phase were observed in situ by X-ray diffraction under vacuum. The heat treatment was conducted at different maximum temperatures up to 450 °C and the resulting particle product was analysed. The experiments were complemented by differential scanning calorimetry (DSC) measurements up to liquidus temperature. The start temperatures of the spinodal phase transformation and particle aggregation were evaluated. PMID:25929324

  18. 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).

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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

  6. 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. PMID:27054770

  7. 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

  8. 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

  9. 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.

  10. Comparative Cytotoxicity Study of Silver Nanoparticles (AgNPs) in a Variety of Rainbow Trout Cell Lines (RTL-W1, RTH-149, RTG-2) and Primary Hepatocytes

    PubMed Central

    Connolly, Mona; Fernandez-Cruz, Maria-Luisa; Quesada-Garcia, Alba; Alte, Luis; Segner, Helmut; Navas, Jose M.

    2015-01-01

    Among all classes of nanomaterials, silver nanoparticles (AgNPs) have potentially an important ecotoxicological impact, especially in freshwater environments. Fish are particularly susceptible to the toxic effects of silver ions and, with knowledge gaps regarding the contribution of dissolution and unique particle effects to AgNP toxicity, they represent a group of vulnerable organisms. Using cell lines (RTL-W1, RTH-149, RTG-2) and primary hepatocytes of rainbow trout (Oncorhynchus mykiss) as in vitro test systems, we assessed the cytotoxicity of the representative AgNP, NM-300K, and AgNO3 as an Ag+ ion source. Lack of AgNP interference with the cytotoxicity assays (AlamarBlue, CFDA-AM, NRU assay) and their simultaneous application point to the compatibility and usefulness of such a battery of assays. The RTH-149 and RTL-W1 liver cell lines exhibited similar sensitivity as primary hepatocytes towards AgNP toxicity. Leibovitz’s L-15 culture medium composition (high amino acid content) had an important influence on the behaviour and toxicity of AgNPs towards the RTL-W1 cell line. The obtained results demonstrate that, with careful consideration, such an in vitro approach can provide valuable toxicological data to be used in an integrated testing strategy for NM-300K risk assessment. PMID:26006119

  11. 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

  12. Sonochemically synthesized mono and bimetallic Au-Ag reduced graphene oxide based nanocomposites with enhanced catalytic activity.

    PubMed

    Neppolian, Bernaurdshaw; Wang, Chang; Ashokkumar, Muthupandian

    2014-11-01

    Graphene oxide (GO) supported Ag and Au mono-metallic and Au-Ag bimetallic catalysts were synthesized using a sonochemical method. Bimetallic catalysts containing different weight ratios of Au and Ag were loaded onto GO utilizing a low frequency horn-type ultrasonicator. High frequency ultrasonication was used to efficiently reduce Ag(I) and Au(III) ions in the presence of polyethylene glycol and 2-propanol. Transmission electron microscopy (TEM-EDX) and X-ray photoelectron spectroscopy were used to analyze the morphology, size, shape and chemical oxidation states of the prepared metallic catalysts on GO. The catalytic efficiency of the prepared catalysts were compared using 4-nitrophenol (4-NP) reduction reaction and the subsequent formation of 4-aminophenol (4-AP) that was also monitored using UV-vis spectrophotometry. The results revealed that Au-Ag-GO bimetallic catalysts showed high activity for the conversion of 4-NP to 4-AP than their monometallic counterparts. Amongst different weight ratios (1:1, 1:2 and 2:1) between Au and Ag, the 1:2 (Au:Ag) catalyst exhibited very good catalytic performance for the conversion of 4-NP to 4-AP. A total reduction of 4-NP took place within a short period of time if Au-GO was reduced first followed by Ag reduction, whereas a lower reduction rate was observed if Ag-GO was reduced first. The same trend was observed for all the ratios of bimetallic catalysts prepared by this method. The initial unfavorable reduction potential of Ag(I) is likely to be responsible for the above order. It was found that applying dual frequency ultrasonication was a highly effective way of preparing bimetallic catalysts requiring relatively low levels of added chemicals and producing bimetallic catalysts with GO with improved catalytic efficiency. PMID:24582660

  13. 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

  14. 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

  15. 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+}.

  16. 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

  17. Laser ablation of AgSbS(2) and cluster analysis by time-of-flight mass spectrometry.

    PubMed

    Houska, Jan; Peña-Méndez, Eladia Maria; Kolár, Jakub; Frumar, Miloslav; Wágner, Tomás; Havel, Josef

    2009-06-01

    Thin films of AgSbS(2) are important for phase-change memory applications. This solid is deposited by various techniques, such as metal organic chemical vapour deposition or laser ablation deposition, and the structure of AgSbS(2)(s), as either amorphous or crystalline, is already well characterized. The pulsed laser ablation deposition (PLD) of solid AgSbS(2) is also used as a manufacturing process. However, the processes in plasma have not been well studied. We have studied the laser ablation of synthesized AgSbS(2)(s) using a nitrogen laser of 337 nm and the clusters formed in the laser plume were identified. The ablation leads to the formation of various single charged ternary Ag(p)Sb(q)S(r) clusters. Negatively charged AgSbS(4) (-), AgSb(2)S(3) (-), AgSb(2)S(4) (-), AgSb(2)S(5) (-) and positively charged ternary AgSbS(+), AgSb(2)S(+), AgSb(2)S(2) (+), AgSb(2)S(3) (+) clusters were identified. The formation of several singly charged Ag(+), Ag(2) (-), Ag(3) (-), Sb(3) (+), Sb(3) (-), S(8) (+) ions and binary Ag(p)S(r) clusters such as AgSb(2) (-), Ag(3)S(-), SbS(r) (-) (r = 1-5), Sb(2)S(-), Sb(2)S(2) (-), Sb(3)S(r) (-) (r = 1-4) and AgS(2) (+), SbS(+), SbS(2) (+), Sb(2)S(+), Sb(2)S(2) (+), Sb(3)S(r) (+) (r = 1-4), AgSb(2) (+) was also observed. The stoichiometry of the clusters was determined via isotopic envelope analysis and computer modeling. The relation of the composition of the clusters to the crystal structure of AgSbS(2) is discussed. PMID:19434598

  18. 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.

  19. 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

  20. Foliar exposure of the crop Lactuca sativa to silver nanoparticles: evidence for internalization and changes in Ag speciation.

    PubMed

    Larue, Camille; Castillo-Michel, Hiram; Sobanska, Sophie; Cécillon, Lauric; Bureau, Sarah; Barthès, Véronique; Ouerdane, Laurent; Carrière, Marie; Sarret, Géraldine

    2014-01-15

    The impact of engineered nanomaterials on plants, which act as a major point of entry of contaminants into trophic chains, is little documented. The foliar pathway is even less known than the soil-root pathway. However, significant inputs of nanoparticles (NPs) on plant foliage may be expected due to deposition of atmospheric particles or application of NP-containing pesticides. The uptake of Ag-NPs in the crop species Lactuca sativa after foliar exposure and their possible biotransformation and phytotoxic effects were studied. In addition to chemical analyses and ecotoxicological tests, micro X-ray fluorescence, micro X-ray absorption spectroscopy, time of flight secondary ion mass spectrometry and electron microscopy were used to localize and determine the speciation of Ag at sub-micrometer resolution. Although no sign of phytotoxicity was observed, Ag was effectively trapped on lettuce leaves and a thorough washing did not decrease Ag content significantly. We provide first evidence for the entrapment of Ag-NPs by the cuticle and penetration in the leaf tissue through stomata, for the diffusion of Ag in leaf tissues, and oxidation of Ag-NPs and complexation of Ag(+) by thiol-containing molecules. Such type of information is crucial for better assessing the risk associated to Ag-NP containing products. PMID:24275476

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. Optical fiber hydrogen sensor based on light reflection and a palladium-sliver thin film

    NASA Astrophysics Data System (ADS)

    Cui, Lu-Jun; Shang, Hui-Chao; Zhang, Gang; Zhao, Ze-Xiang; Zhou, Jun

    2011-07-01

    Thin alloy films of palladium (Pd) and silver (Ag) are deposited onto glass substrates via the direct current (DC) magnetron technique. The hydrogen sensor probe consists of optical fiber bundle and Pd/Ag optical thin film. When the sensor is exposed to hydrogen, the refractive index of Pd/Ag optical thin layer will diminish and cause attenuation changes of the reflective light. It is observed that the thickness of Pd/Ag alloy layer can affect the hydrogen sensor signal. Under different substrate temperatures, several Pd/Ag samples are coated with different thicknesses of Pd/Ag alloy, and the results of a hydrogen sensor based on reflective light from the Pd/Ag alloy thin film are discussed.

  6. 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.

  7. The AgNORs.

    PubMed

    Derenzini, M

    2000-04-01

    The structure and the function of interphase AgNORs and the importance of the "AgNOR" parameter in tumor pathology have been reviewed. Interphase AgNORs are structural-functional units of the nucleolus in which all the components necessary for ribosomal RNA synthesis are located. Two argyrophilic proteins involved in rRNA transcription and processing, nucleolin and nucleophosmin, are associated with interphase AgNORs and are responsible for their stainability with silver methods, thus allowing interphase AgNORs to be visulaized at light microscopic level, also in routine cyto-histopathological preparations. The number of interphase AgNORs is strictly related to rRNA transcriptional activity and, in continuously proliferating cells, to the rapidity of cell proliferation. Evaluation of the quantitative distribution of interphase AgNORs has been applied in tumor pathology both for diagnostic and prognostic purposes. The "AgNOR" parameter has been proved to represent a reliable tool for defining the clinical outcome of cancer disease, being an independent prognostic factor in many types of tumors. PMID:10588056

  8. 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.

  9. 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.

  10. Porous Au-Ag Alloy Particles Inlaid AgCl Membranes As Versatile Plasmonic Catalytic Interfaces with Simultaneous, in Situ SERS Monitoring.

    PubMed

    Cao, Qi; Yuan, Kaiping; Liu, Qinghe; Liang, Chongyun; Wang, Xiang; Cheng, Yi-Feng; Li, Qingqing; Wang, Min; Che, Renchao

    2015-08-26

    We present a novel porous Au-Ag alloy particles inlaid AgCl membrane as plasmonic catalytic interfaces with real-time, in situ surface-enhanced Raman spectroscopy (SERS) monitoring. The Au-Ag alloy particles inlaid AgCl membranes were obtained via a facile two-step, air-exposed, and room-temperature immersion reaction with appropriate annealing process. Owing to the designed integration of semiconductor component AgCl and noble metal Au-Ag particles, both the catalytic reduction and visible-light-driven photocatalytic activities toward organic contaminants were attained. Specifically, the efficiencies of about 94% of 4-nitrophenol (4-NP, 5 × 10(-5) M) reduction after 8 min of reaction, and degradation of rhodamine 6G (R6G, 10(-5) M) after 12 min of visible light irradiation were demonstrated. Moreover, efficiencies of above 85% of conversion of 4-NP to 4-aminophenol (4-AP) and 90% of R6G degradation were achieved as well after 6 cycles of reactions, by which robust recyclability was confirmed. Further, with distinct SERS signals generated simultaneously from the surfaces of Au-Ag particles under laser excitation, in situ SERS monitoring of the process of catalytic reactions with superior sensitivity and linearity has been realized. Overall, the capability of the Au-Ag particles inlaid AgCl membranes to provide SERS monitored catalytic and visible-light-driven photocatalytic conversion of organic pollutants, along with their mild and cost-effective fabrication method, would make sense for in-depth understanding of the mechanisms of (photo)catalytic reactions, and also future development of potable, multifunctional and integrated catalytic and sensing devices. PMID:26263301

  11. 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.

  12. 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.

  13. 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 %).

  14. 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.

  15. 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.

  16. 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

  17. 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. PMID:26396079

  18. 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.

  19. 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.

  20. In Situ Localized Surface Plasmon Resonance (LSPR) Spectroscopy to Investigate Kinetics of Chemical Bath Deposition of CdS Thin Films

    DOE PAGESBeta

    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

  1. 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.

  2. 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.

  3. NMR Studies of Nitrophorin Distal Pocket Side Chain Effects on the Heme Orientation and Seating of NP2 as Compared to NP1

    PubMed Central

    Shokhireva, Tatiana K.; Berry, Robert E.; Zhang, Hongjun; Shokhirev, Nikolai V.; Walker, F. Ann

    2011-01-01

    The nitrophorins (NP) of the adult blood-sucking insect Rhodnius prolixus fall into two pairs based on sequence identity (NP1,4 (90%) and NP2,3 (79%), which differ significantly in the size of side chains of residues which contact the heme. These residues include those in the distal pocket of NP2 (I120) and NP1 (T121) and the “belt” that surrounds the heme of NP2 (S40, F42), and NP1(A42, L44). To determine the importance of these residues and others conserved or very similar for the two pairs, including L122(123), L132(133), appropriate mutants of NP2 and NP1 have been prepared and studied by 1H NMR spectroscopy. Wild-type NP2 has heme orientation ratio (A:B) of 1:8 at equilibrium, while wild-type NP1 has A:B ~1:1 at equilibrium. Another difference between NP2 and NP1 is in the heme seating with regard to His57(59). It is found that among the distal pocket residues investigated, the residue most responsible for heme orientation and seating is I120(T121). F42(L44) and L106(F107) may also be important, but must be investigated in greater detail. PMID:21767470

  4. 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

  5. Multipolar ordering in NpO2 below 25 K

    NASA Astrophysics Data System (ADS)

    Caciuffo, R.; Paixão, J. A.; Detlefs, C.; Longfield, M. J.; Santini, P.; Bernhoeft, N.; Rebizant, J.; Lander, G. H.

    2003-07-01

    The phase transition at T0 = 25 K in NpO2 and the single-ion nature of the Np 5f electrons is examined in the light of the results of resonant x-ray scattering experiments at the M4 Np edge. These experiments exclude usual magnetic dipole ordering at T0, and provide direct evidence of long-range order of the electric quadrupole moment with Gamma5 symmetry. The phase transition is purely electronic and does not involve either internal or external crystallographic distortions, so the symmetry of the system remains cubic. The primary order parameter (OP) is associated with Gamma4t magnetic octupoles, ordering in a triple-q longitudinal structure defined by the three wavevectors of the langle001rangle star. Magnetic octupolar order breaks invariance under time reversal and induces the order of electric quadrupoles as the secondary OP. The resulting ground state is a singlet with zero dipole magnetic moment.

  6. 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)

  7. 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

  8. Dilute Nitride GaNP Wide Bandgap Solar Cells Grown by Gas-Source Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Sukrittanon, Supanee

    Integration of III-V semiconductors and Si is a very attractive means to achieve low-cost high-efficiency solar cells. A promising configuration is to utilize a dual-junction solar cell, in which Si is employed as the bottom junction and a wide-bandgap III-V semiconductor as the top junction. The use of a III-V semiconductor as a top junction offers the potential to achieve higher efficiencies than today's best Si solar cell. Dilute nitride GaNP is a promising candidate for the top cell in dual-junction solar cells because it possesses several extremely important attributes: a direct-bandgap that is also tunable as well as easily-attained lattice-match with Si. As a first step towards integration of GaNP solar cells onto Si, the goal of this dissertation is to optimize and demonstrate GaNP solar cells grown by gas-source molecular beam epitaxy (GSMBE) on GaP (001) substrate. The dissertation is divided into three major parts. In the first part, we demonstrate ˜ 2.05 eV ([N]˜ 1.8%) dilute nitride GaNP thin film solar cells, in which the GaNP is closely lattice-matched to Si, on GaP substrates. From transmission electron microscopy (TEM), the device exhibits defects only at the GaNP/GaP interface, and no threading dislocations in an active layer are observed. Our best GaNP solar cell achieved an efficiency of 7.9% with anti-reflection (AR) coating and no window layer. This GaNP solar cell's efficiency is higher than the most efficient GaP solar cell to date and higher than other solar cells with similar direct bandgap (InGaP, GaAsP). Through a systematic study of the structural, electrical, and optical properties of the device, efficient broadband optical absorption and enhanced solar cell performance using GaNP are demonstrated. In the second part, we demonstrate the successful fabrication of GaP/GaNP core/shell microwires utilizing a novel technique: top-down reactive-ion etching (RIE) to create the cores and MBE to create the shells. Systematic studies have been

  9. 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).

  10. 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.

  11. 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.

  12. 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.

  13. Comparison of the Carba NP, Modified Carba NP, and Updated Rosco Neo-Rapid Carb Kit Tests for Carbapenemase Detection

    PubMed Central

    AbdelGhani, Sameh; Thomson, Gina K.; Snyder, James W.

    2015-01-01

    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

  14. 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

  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. Ag/Au mixed sites promote oxidative coupling of methanol on the alloy surface.

    PubMed

    Xu, Bingjun; Siler, Cassandra G F; Madix, Robert J; Friend, Cynthia M

    2014-04-14

    Nanoporous gold, a dilute alloy of Ag in Au, activates molecular oxygen and promotes the oxygen-assisted catalytic coupling of methanol. Because this trace amount of Ag inherent to nanoporous gold has been proposed as the source of oxygen activation, a thin film Ag/Au alloy surface was studied as a model system for probing the origin of this reactivity. Thin alloy layers of Ag(x)Au(1-x), with 0.15≤x≤0.40, were examined for dioxygen activation and methanol self-coupling. These alloy surfaces recombine atomic oxygen at different temperatures depending on the alloy composition. Total conversion of methanol to selective oxidation products, that is, formaldehyde and methyl formate, was achieved at low initial oxygen coverage and at low temperature. Reaction channels for methyl formate formation occurred on both Au and Au/Ag mixed sites with a ratio, as was predicted from the local 2-dimensional composition. PMID:24633724

  17. Adaptive response of trivial activated sludge towards toxic effect of oNP, PCP and combination oNP/PCP

    SciTech Connect

    Topalova, Y.; Dimkov, R. . Faculty of Biology); Kozuharov, D. )

    1999-01-01

    The reaction of the real aerobic activated sludge taken from the Sofia Waste Water Treatment Plant (SWWTP) and treated with the xenobiotics pentachlorphenol (PCP) (0.16 mMol), ortho-nitrophenol (oNP) (0.58 mMol) and with a combination of PCP (0.08 mMol), oNP (0.29 mMol) has been investigated in a model detoxification process. The adaptive changes are studied in the microbial structure level and at the level of changes in the qualitative and quantitative parameters of the macro-organisms in the activated sludge (consuments of 1 and 2 level). The presence of several different taxonomic groups has been shown by other researchers to be essential in the detoxification process. The quantitative changes in these taxonomic and physiological groups of micro-organisms are studied. The number of micro-organisms from Pseudomonas, Acinetobacter and the bacteria from the xenobiotic-catabolizing complex considerably increased with the individual and the combined effect of the xenobiotics oNP, PCP and oNP PCP. At the same time the toxic shock leads to a remarkable reduction of NH[sub 3] releasing, nitrifying bacteria and those from family Enterobacteriaceae. It is ascertained that the number of Ciliata, Flagellata apochromata, Oligochaeta and Rotatoria is strongly decreased in the series of samples treated with xenobiotics. The leading role of micro-organisms in the real detoxification of hazardous pollutants was experimentally confirmed by research.

  18. 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…

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Conductance switching in Ag2S devices fabricated by in situ sulfurization

    NASA Astrophysics Data System (ADS)

    Morales-Masis, M.; van der Molen, S. J.; Fu, W. T.; Hesselberth, M. B.; van Ruitenbeek, J. M.

    2009-03-01

    We report a simple and reproducible method to fabricate switchable Ag2S devices. The α-Ag2S thin films are produced by a sulfurization process after silver deposition on an Si substrate. Structure and composition of the Ag2S are characterized using XRD and RBS. Our samples show semiconductor behaviour at low bias voltages, whereas they exhibit reproducible bipolar resistance switching at higher bias voltages. The transition between both types of behaviour is observed by hysteresis in the I-V curves, indicating decomposition of the Ag2S, increasing the Ag+ ion mobility. The as-fabricated Ag2S samples are a good candidate for future solid state memory devices, as they show reproducible memory resistive properties and they are fabricated by an accessible and reliable method.

  4. Conductance switching in Ag(2)S devices fabricated by in situ sulfurization.

    PubMed

    Morales-Masis, M; van der Molen, S J; Fu, W T; Hesselberth, M B; van Ruitenbeek, J M

    2009-03-01

    We report a simple and reproducible method to fabricate switchable Ag(2)S devices. The alpha-Ag(2)S thin films are produced by a sulfurization process after silver deposition on an Si substrate. Structure and composition of the Ag(2)S are characterized using XRD and RBS. Our samples show semiconductor behaviour at low bias voltages, whereas they exhibit reproducible bipolar resistance switching at higher bias voltages. The transition between both types of behaviour is observed by hysteresis in the I-V curves, indicating decomposition of the Ag(2)S, increasing the Ag(+) ion mobility. The as-fabricated Ag(2)S samples are a good candidate for future solid state memory devices, as they show reproducible memory resistive properties and they are fabricated by an accessible and reliable method. PMID:19417506

  5. Differential Responsivity of the Organic-Inorganic Ag/n-GaAs/p-CuPc/Ag Photoelectric Sensor

    NASA Astrophysics Data System (ADS)

    Karimov, Kh. S.; Qazi, I.; Fedorov, M. I.; Moiz, S. A.; Khan, T. A.; Senin, H. B.

    2007-05-01

    A thin film of copper phthalocynanine (CuPc) as p-type semiconductor was deposited by vacuum evaporation on an n-type GaAs single-crystal semiconductor substrate. Then semitransparent Ag thin film having gradient of thickness was deposited on CuPc film by thermal evaporation in vacuum to fabricate Ag/n-GaAs/p-CuPc/Ag sensor. Due to gradient of thickness, 6% and 10% of the incident light can be transmitted through the silver film in the edge and in the center of the sample respectively. Open circuit voltage and short circuit current were measured by exposing only a small area of the sensor to light i.e. in differential mode of operation. It was observed that open-circuit voltage and short-circuit current depends on position of the exposed area of the sensor to light. In differential mode of operation the open-circuit voltage and short circuit current versus intensity of illumination showed less non linearity as compared to integral mode of operation. On the basis of experimental data, an equivalent circuit of the sensor was designed and its computer simulation was carried out. The simulated data matched reasonably with the experimental curves. It was found that in differential mode of operation the Ag/n-GaAs/p-CuPc/Ag sensor's output voltage and current depends on the position of light beam probe. Due to this the sensor may be used as a photoelectric displacement transducer.

  6. 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.

  7. 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.

  8. 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.

  9. np elastic scattering analyzing power characteristics at intermediate energies

    SciTech Connect

    Abegg, R.; Ahmad, M.; Bandyopadhyay, D.; Birchall, J.; Cairns, E.B.; Chantziantoniou, K.; Coombes, G.H.; Davis, C.A.; Davison, N.E.; Delheij, P.P.J.; Green, P.W.; Greeniaus, L.G.; Gubler, H.P.; Healey, D.C.; Lapointe, C.; Lee, W.P.; McDonald, W.J.; Miller, C.A.; Moss, G.A.; Page, S.A.; Plattner, G.R.; Poffenberger, P.R.; Ramsay, W.D.; Rodning, N.L.; Roy, G.; Soukup, J.; Svenne, J.P.; Tkachuk, R.R.; van Oers, W.T.H.; Wait, G.D.; Watson, J.W.; Ye, Y.; Zhang, Y.P. University of Manitoba, Department of Physics, Winnipeg, Manitoba, Canada R3T 2N2 University of Alberta, Department of Physics, Edmonton, Alberta, Canada T6G 2N5 University of Basel, Institute of Physics, CH-4000 Basel, Switzerland Kent State University, Department of Physics, Kent, Ohio 44242)

    1989-11-01

    Recent measurements of charge symmetry breaking in the {ital np} system at 477 MeV, and of {ital A}{sub 00{ital nn}} for {ital np} elastic scattering at 220, 325, and 425 MeV also yield accurate analyzing power data. These data allow the energy dependence of the analyzing power zero-crossing angle and the slope of the analyzing power at the zero-crossing angle to be determined. The incident neutron energies span a region where the zero-crossing angle is strongly energy dependent ({ital E}{sub {ital n}}{lt}250 MeV) to where it is almost independent of energy ({ital E}{sub {ital n}}{gt}350 MeV). The results are compared to current phase-shift analysis predictions, recently published data, and the predictions of the Bonn and Paris potentials.

  10. Covariant spectator theory of np scattering: Deuteron quadrupole moment

    DOE PAGESBeta

    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

  11. 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.

  12. n-p short-range correlations from (p,2p+n) measurements

    NASA Astrophysics Data System (ADS)

    Tang, A.; Watson, J. W.; Alster, J.; Arsyan, G.; Averichev, Y.; Barton, D.; Baturin, V.; Bukhtoyarova, N.; Carroll, A.; Heppelmann, S.; Kawabata, T.; Leksanov, A.; Makdisi, Y.; Malki, A.; Minina, E.; Navon, I.; Nicholson, H.; Ogawa, A.; Panebratsev, Yu.; Piasetzky, E.; Schetkovsky, A.; Shimanskiy, S.; Yoshida, H.; Zhalov, D.

    2000-12-01

    Recently, a new technique for measuring short-range NN correlations in nuclei (NN SRCs) was reported by the E850 collaboration, using data from the EVA spectrometer at the AGS at Brookhaven National Laboratory In this talk, we will report on a larger set of data from new measurement by the collaboration, utilizing the same technique. This technique is based on a very simple kinematic approach. For quasielastic knockout of protons from a nucleus (12C(p,2p) was used for the current work), we can reconstruct the momentum pf of the struck proton in the nucleus before the reaction, from the three momenta of the two detected protons, p1 and p2 and the three momentum of the incident proton, p0:pf=p1+p2-p0 If there are significant n-p SRCs, then we would expect to find a neutron with momentum -pf in coincidence with the two protons, provided pf is larger than the Fermi momentum kF for the nucleus (˜220 MeV/c for 12C). Our results reported here confirm the earlier results from the E850 collaboration.

  13. 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

  14. The Temporospatial Evolution of NP-related and Independent Tangleopathies: Implications for Dementia Staging

    PubMed Central

    Royall, Donald R.; Palmer, Raymond F.

    2015-01-01

    Neuritic plaque (NP) formation can be dated in vivo. This analysis attempts to “date” the progression of neurofibrillary tangles (NFT) using the spatial distribution of NP as a reference. Autopsy data from 471 participants in the Honolulu-Asia Aging Study (HAAS) were combined into latent factor measures of NFT and NP counts. The variance in “early” and “late” NP pathology was used to estimate the spatial distribution of “early” and “late” NFT formation. A third latent factor representing “non-NP-related NFT” was also constructed. “Early”NP and ‘Late”NP correlated significantly with objectively early and later cognitive performance, respectively. In contrast to our expectations, neocortical NFT correlated best with “early” NP pathology, while NFT in allocortical structures correlated best with “late” NP pathology. Therefore, the NP-related fraction of NFT appears to be co-localized spatially with NP. However, since the latter evolve corticofugally in time, this suggests that NP-related NFT do so as well. Corticotropic NFT formation must therefore be either un-related to NP formation, a temporally distinct process, or both. PMID:24577462

  15. HNO₃-assisted polyol synthesis of ultralarge single-crystalline Ag microplates and their far propagation length of surface plasmon polariton.

    PubMed

    Chang, Cheng-Wei; Lin, Fan-Cheng; Chiu, Chun-Ya; Su, Chung-Yi; Huang, Jer-Shing; Perng, Tsong-Pyng; Yen, Ta-Jen

    2014-07-23

    We developed a HNO3-assisted polyol reduction method to synthesize ultralarge single-crystalline Ag microplates routinely. The edge length of the synthesized Ag microplates reaches 50 μm, and their top facets are (111). The mechanism for dramatically enlarging single-crystalline Ag structure stems from a series of competitive anisotropic growths, primarily governed by carefully tuning the adsorption of Ag(0) by ethylene glycol and the desorption of Ag(0) by a cyanide ion on Ag(100). Finally, we measured the propagation length of surface plasmon polaritons along the air/Ag interface under 534 nm laser excitation. Our single-crystalline Ag microplate exhibited a propagation length (11.22 μm) considerably greater than that of the conventional E-gun deposited Ag thin film (5.27 μm). PMID:24987801

  16. 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.

  17. 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.

  18. P/NP, and the Quantum Field Computer

    NASA Astrophysics Data System (ADS)

    Freedman, Michael H.

    1998-01-01

    The central problem is 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 neq 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 Turning 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.

  19. 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

  20. 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.

  1. 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

  2. Ag Nanoparticle-Sensitized WO3 Hollow Nanosphere for Localized Surface Plasmon Enhanced Gas Sensors.

    PubMed

    Yao, Yao; Ji, Fangxu; Yin, Mingli; Ren, Xianpei; Ma, Qiang; Yan, Junqing; Liu, Shengzhong Frank

    2016-07-20

    Ag nanoparticle (NP)-sensitized WO3 hollow nanospheres (Ag-WO3-HNSs) are fabricated via a simple sonochemical synthesis route. It is found that the Ag-WO3-HNS shows remarkable performance in gas sensors. Field-emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) images reveal that the Agx-WO3 adopts the HNS structure in which WO3 forms the outer shell framework and the Ag NPs are grown on the inner wall of the WO3 hollow sphere. The size of the Ag NPs can be controlled by adjusting the addition amount of WCl6 during the reaction. The sensor Agx-WO3 exhibits extremely high sensitivity and selectivity toward alcohol vapor. In particular, the Ag(15nm)-WO3 sensor shows significantly lower operating temperature (230 °C), superior detection limits as low as 0.09 ppb, and faster response (7 s). Light illumination was found to boost the sensor performance effectively, especially at 405 and 900 nm, where the light wavelength resonates with the absorption of Ag NPs and the surface oxygen vacancies of WO3, respectively. The improved sensor performance is attributed to the localized surface plasmon resonance (LSPR) effect. PMID:27348055

  3. Alloyed Crystalline Au-Ag Hollow Nanostructures with High Chemical Stability and Catalytic Performance.

    PubMed

    Liu, Renxiao; Guo, Jianhua; Ma, Gang; Jiang, Peng; Zhang, Donghui; Li, Dexing; Chen, Lan; Guo, Yuting; Ge, Guanglu

    2016-07-01

    For bimetallic nanoparticles (NPs), the degree of alloying is beginning to be recognized as a significant factor affecting the NP properties. Here, we report an alloyed crystalline Au-Ag hollow nanostructure that exhibits a high catalytic performance, as well as structural and chemical stability. The Au-Ag alloyed hollow and porous nanoshell structures (HPNSs) with different morphologies and subnanoscale crystalline structures were synthesized by adjusting the size of the sacrificial Ag NPs via a galvanic replacement reaction. The catalytic activities of the nanomaterials were evaluated by the model reaction of the catalytic reduction of p-nitrophenol by NaBH4 to p-aminophenol. The experimental results show that the subnanoscale crystalline structure of the Au-Ag bimetallic HPNSs has much greater significance than the apparent morphology does in determining the catalytic ability of the nanostructures. The Au-Ag alloyed HPNSs with better surface crystalline alloying microstructures and open morphologies were found to exhibit much higher catalytic reaction rates and better cyclic usage efficiencies, probably because of the better dispersion of active Au atoms within these materials. These galvanic replacement-synthesized alloyed Au-Ag HPNSs, fabricated by a facile method that avoids Ag degradation, have potential applications in catalysis, nanomedicine (especially in drug/gene delivery and cancer theranostics), and biosensing. PMID:27268019

  4. MoOx modified Ag anode for top-emitting organic light-emitting devices

    NASA Astrophysics Data System (ADS)

    Cao, Jin; Jiang, XueYin; Zhang, ZhiLin

    2006-12-01

    Efficient top-emitting organic light-emitting devices (TOLEDs) using a thin MoOx layer modified Ag as the effective hole-injection anode are demonstrated. With tris-(8-hydroxy quinoline)aluminum as emitting layer and trilayer LiF /Al/Ag as semitransparent cathode, the Ag /MoOx based TOLED shows a tune-on voltage of 2.67V and a maximum current efficiency of 7.27cd/A, which are much better than those (3.92V, 6.12cd/A) obtained from Ag /Ag2O based TOLED and those (5.25V, 3.5cd/A) obtained from the corresponding bottom-emitting organic light-emitting devices. Contact potential difference measurement shows that the work function of Ag /MoOx is higher than those of Ag /Ag2O and ozone-treated indium tin oxide, leading to a stronger hole injection. The good performance of Ag /MoOx based TOLED is attributed to the efficient hole injection from the Ag /MoOx anode as well as a microcavity effect.

  5. 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

  6. 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.

  7. 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.

  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. Size saturation in low energy ion beam synthesized nanoparticles in silica glass: 50 keV Ag{sup -} ions implantation, a case study

    SciTech Connect

    Kuiri, P. K.

    2010-09-15

    Fluence-dependent formation of Ag nanoparticles (NPs) in silica glass by 50 keV Ag{sup -} ions implantation has been studied. Samples implanted with fluences of 2x10{sup 16} ions cm{sup -2} and above are found to show an absorption band at around 410 nm, corresponding to the surface plasmon resonance (SPR) of the Ag NPs in silica glass. An increase in SPR peak intensity with increase in fluence has been observed up to a fluence of 7x10{sup 16} ions cm{sup -2} (F7), after which the absorption intensity shows a saturation. Simulations of the optical absorption spectra also indicated an increase in the absorption intensity and hence the size of the NPs with increase in fluence up to F7, beyond which NP size is seen to saturate. The saturation of fluence and the SPR intensity (or NP size) have been explained as coming due to a break up of larger Ag NPs formed near the surface by displacement spikes induced by subsequently incident Ag ions against their regrowth from the movement of Ag atoms toward the surface and their sputtering loss. Further, we have compared our observations with the earlier data on saturation of fluence and size of NPs in cases of Au and Zn, and concluded that the saturation of both fluence and NP size are general phenomena for low energy high fluence metal ion implantation.

  10. 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

  11. Ag K- and L3-edge XAFS study on Ag species in Ag/Ga2O3 photocatalysts

    NASA Astrophysics Data System (ADS)

    Yamamoto, M.; Yoshida, T.; Yamamoto, N.; Nomoto, T.; Yamamoto, A.; Yoshida, H.; Yagi, S.

    2016-05-01

    Ag loaded Ga2O3 (Ag/Ga2O3) shows photocatalytic activity for reduction of CO2 with water. Ag L3-edge XANES and K-edge EXAFS spectra were measured for various Ag/Ga2O3 samples, which suggested that structural and chemical states of Ag species varied with the loading amount of Ag and the preparation method. The Ag species were metallic Ag particles with an AgGaO2-like interface structure in the sample with high loading amount of Ag while predominantly Ag metal clusters in the sample with low loading amount of Ag. The XANES feature just above the edge represented the interaction between the Ag species and the Ga2O3 surface, showing that the Ag metal clusters had more electrons in the d-orbitals by interacting with the Ga2O3 surface, which would contribute the high photocatalytic activity.

  12. 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.

  13. 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.

  14. 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.

  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. Synthesis of Ag nanoparticle-decorated 2,4,6-tris(2-pyridyl)-1,3,5-triazine nanobelts and their application for H2O2 and glucose detection.

    PubMed

    Qin, Xiaoyun; Lu, Wenbo; Luo, Yonglan; Chang, Guohui; Asiri, Abdullah M; Al-Youbi, Abdulrahman O; Sun, Xuping

    2012-02-21

    The present paper reports on the first preparation of 2,4,6-tris(2-pyridyl)-1,3,5-triazine nanobelts (TPTNBs) by adjusting the pH value of the solution and the subsequent synthesis of Ag nanoparticle (AgNP)-decorated TPTNBs (AgNP-TPTNBs) by mixing an aqueous AgNO(3) solution with preformed TPTNBs without use of any external reducing agent. It is found that the resultant AgNP-TPTNBs exhibit notable catalytic performance for H(2)O(2) reduction. A glucose biosensor was fabricated by immobilizing glucose oxidase (GOD) onto a AgNP-TPTNBs-modified glassy carbon electrode (GCE) for glucose detection. The constructed glucose sensor has a wide linear response range from 3 mM to 20 mM (r: 0.999) with a detection limit of 190 μM. It is further shown that this glucose biosensor can be used for glucose detection in human blood serum. PMID:22179818

  17. 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 40nm 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 1cm×3cm 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 12days of operation. Further analysis indicated that silver ion release can be sustained for approximately 25days. 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. PMID:26952479

  18. 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.

  19. 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.

  20. Synthesis of Ag/ZnO nanostructures by different methods and investigation of their photocatalytic efficiency for 4-nitrophenol degradation

    NASA Astrophysics Data System (ADS)

    Divband, B.; Khatamian, M.; Eslamian, G. R. Kazemi; Darbandi, M.

    2013-11-01

    In this paper, Ag/ZnO photocatalysts with different Ag loadings were prepared by photo reduction, chemical reduction and polyacrylamide-gel methods. The Ag/ZnO photocatalysts were characterized by XRD, SEM, TEM, EDS and DRUV-vis methods. The results of the photocatalytic degradation of 4-NP in aqueous suspensions showed that silver ions doping greatly improved the photocatalytic efficiency of ZnO nanocrystallites. The enhancement of photocatalytic activity is due to the fact that the modification of ZnO with an appropriate amount of Ag can increase the separation efficiency of photogenerated electrons and holes in ZnO, and the improvement of photo stability of ZnO is attributed to a considerable decrease of the surface defect sites of ZnO after the Ag loading. The chemisorptions of molecular oxygen and the chemisorption of atomic oxygen on Ag in the Ag/ZnO photocatalysts were observed. It was found that the metallic Ag in the Ag/ZnO photocatalysts does play a new role of O2 chemisorption sites except for electron acceptor, by which chemisorbed molecular oxygen reacts with photogenerated electrons to form active oxygen species, and thus facilitates the trapping of photogenerated electrons and further improves the photocatalytic activity of the Ag/ZnO photocatalysts. Also the method of preparation is regarded as important factors for determining photocatalysis. The best photocatalytic performance was exhibited for Ag/ZnO prepared by polyacrylamide gel method in comparison with chemical reduction and photo reduction method and the optimum Ag content was approximately 0.5%.

  1. Synthesis of functional SiO₂-coated graphene oxide nanosheets decorated with Ag nanoparticles for H₂O₂ and glucose detection.

    PubMed

    Lu, Wenbo; Luo, Yonglan; Chang, Guohui; Sun, Xuping

    2011-08-15

    In this paper, we report on the first preparation of well-defined SiO(2)-coated graphene oxide (GO) nanosheets (SiO(2)/GO) without prior GO functionalization by combining sonication with sol-gel technique. The functional SiO(2)/GO nanocomposites (F-SiO(2)/GO) obtained by surface functionalization with NH(2) group were subsequently employed as a support for loading Ag nanoparticles (AgNPs) to synthesize AgNP-decorated F-SiO(2)/GO nanosheets (AgNP/F-SiO(2)/GO) by two different routes: (1) direct adsorption of preformed, negatively charged AgNPs; (2) in situ chemical reduction of silver salts. The morphologies of these nanocomposites were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that the resultant AgNP/F-SiO(2)/GO exhibits remarkable catalytic performance for H(2)O(2) reduction. This H(2)O(2) sensor has a fast amperometric response time of less than 2s. The linear range is estimated to be from 1×10(-4) M to 0.26 M (r=0.998) and the detection limit is estimated to be 4 × 10(-6) M at a signal-to-noise ratio of 3, respectively. We also fabricated a glucose biosensor by immobilizing glucose oxidase (GOD) into AgNP/F-SiO(2)/GO nanocomposite-modified glassy carbon electrode (GCE) for glucose detection. Our study demonstrates that the resultant glucose biosensor can be used for the glucose detection in human blood serum. PMID:21733668

  2. 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

  3. Synthesis and biosensor application of Ag@Au bimetallic nanoparticles based on localized surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Ghodselahi, T.; Arsalani, S.; Neishaboorynejad, T.

    2014-05-01

    This work demonstrates a simple method for synthesizing gold-silver bimetallic nanoparticles (Ag@Au BNPs). Ag@Au BNPs on the carbon thin film are prepared by co-deposition of RF-sputtering and RF-PECVD using acetylene gas and gold-silver target. X-ray diffraction analysis indicates that Au and Ag NPs with FCC crystal structure are formed in our samples. From AFM image and data, average particles size of gold and silver are estimated to be about 5 and 8 nm, respectively. XRD profile and localized surface plasmon resonance (LSPR) spectroscopy indicate that Ag NPs in Ag@Au BNPs composite have a more chemical activity with respect to bare Ag NPs. Biosensor application of Ag@Au BNPs without probe immobilization is introduced too. The change in LSPR absorption peak of Ag@Au BNPs in presence of DNA primer decamer (ten-deoxycytosine) at fM concentrations is investigated. The LSPR absorption peak of Au NPs has a blue shift and the LSPR absorption peak of Ag NPs has a red shift by addition of DNA primer and under DNA exposure up to 1 h. Our sample shows a good response to low concentration of DNA and has a short response time. Both of these are prerequisite for applying this sample as LSPR biosensor chip.

  4. 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.

  5. 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.

  6. 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.

  7. Reply to ''Comment on the 'Energy level analysis of Np/sup 3 +/:LaCl/sub 3/ and Np/sup 3 +/:LaBr/sub 3/' ''

    SciTech Connect

    Carnall, W.T.; Crosswhite, H.; Crosswhite, H.M.; Hessler, J.P.; Edelstein, N.; Conway, J.G.; Shalimoff, G.V.; Sarup, R.

    1981-10-01

    The crystal field parameters in Np/sup 3 +/:Lad/sub 3/ and Np/sup 3 +/:LaBr/sub 3/ are discussed. The arguments of Poon and Newman, regarding the scaling of the crystal field parameters are aknowdged as being correct.(AIP)

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  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. PMID:25456348

  14. 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

  15. Preparation of Ag nanoparticle-decorated poly(m-phenylenediamine) microparticles and their application for hydrogen peroxide detection.

    PubMed

    Tian, Jingqi; Li, Hailong; Lu, Wenbo; Luo, Yonglan; Wang, Lei; Sun, Xuping

    2011-05-01

    The chemical oxidation polymerization of m-phenylenediamine (MPD) by ammonium persulfate (APS) at room temperature results in the formation of poly(m-phenylenediamine) (PMPD) microparticles. The subsequent treatment of such microparticles with an aqueous AgNO(3) solution produces Ag nanoparticle (AgNP)-decorated PMPD microparticles. It was found that as-formed AgNPs exhibited remarkable catalytic performance toward the reduction of hydrogen peroxide (H(2)O(2)). The enzymeless H(2)O(2) sensor constructed with such composites showed a fast amperometric response time of less than 5 s, and the corresponding linear range and detection limit were estimated to be from 0.1 to 30 mM and 4.7 µM, respectively, at a signal-to-noise ratio of 3. PMID:21387026

  16. 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.

  17. 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. PMID:24622377

  18. 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.

  19. 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

  20. 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.

  1. Bimetallic Pt-Ag and Pd-Ag nanoparticles

    SciTech Connect

    Lahiri, Debdutta; Bunker, Bruce; Mishra, Bhoopesh; Zhang, Zhenyuan; Meisel, Dan; Doudna, C. M.; Bertino, M. F.; Blum, Frank D.; Tokuhiro, A. T.; Chattopadhyay, Soma; Shibata, Tomohiro; Terry, Jeff

    2005-04-19

    We report studies of bimetallic nanoparticles with 15%–16% atomic crystal parameters size mismatch. The degree of alloying was also probed in a 2-nm Pt core ssmallest attainable core sized of Pt–Ag nanoparticles scompletely immiscible in bulkd and 20-nm-diameter Pd–Ag nanowires scompletely miscible in bulkd. Particles were synthesized radiolytically, and depending on the initial parameters, they assume spherical or cylindrical snanowired morphologies. In all cases, the metals are seen to follow their bulk alloying characteristics. Also, Pt and Ag segregate in both spherical and wire forms, which indicates that strain due to crystallographic mismatch overcomes the excess surface free energy in the small particles. The Pd–Ag nanowires alloy similar to previously reported spherical Pd–Ag particles of similar diameter and composition

  2. Bimetallic Pt-Ag and Pd-Ag nanoparticles

    SciTech Connect

    Lahiri, Debdutta; Bunker, Bruce; Mishra, Bhoopesh; Zhang, Zhenyuan; Meisel, Dan; Doudna, C.M.; Bertino, M. F.; Blum, Frank D.; Tokuhiro, A.T.; Chattopadhyay, Soma; Shibata, Tomohiro; Terry, Jeff

    2005-05-01

    We report studies of bimetallic nanoparticles with 15%-16% atomic crystal parameters size mismatch. The degree of alloying was probed in a 2-nm Pt core (smallest attainable core size) of Pt-Ag nanoparticles (completely immiscible in bulk) and 20-nm-diameter Pd-Ag nanowires (completely miscible in bulk). Particles were synthesized radiolytically, and depending on the initial parameters, they assume spherical or cylindrical (nanowire) morphologies. In all cases, the metals are seen to follow their bulk alloying characteristics. Pt and Ag segregate in both spherical and wire forms, which indicates that strain due to crystallographic mismatch overcomes the excess surface free energy in the small particles. The Pd-Ag nanowires alloy similar to previously reported spherical Pd-Ag particles of similar diameter and composition.

  3. 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.

  4. 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

  5. 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

  6. 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

  7. What Is Ag-Ed?

    ERIC Educational Resources Information Center

    Lindley, Judy

    Ag-Ed is an agricultural education project aimed at upper primary students, held in conjunction with the Toowoomba Show (similar to a county fair) in Queensland, Australia. The program achieves its purpose of helping children understand the impact and relevance that agriculture has on their everyday lives through two components, an Ag-Ed day and a…

  8. 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.

  9. 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.

  10. Efficient DNA sticker algorithms for NP-complete graph problems

    NASA Astrophysics Data System (ADS)

    Zimmermann, Karl-Heinz

    2002-04-01

    Adleman's successful solution of a seven-vertex instance of the NP-complete Hamiltonian directed path problem by a DNA algorithm initiated the field of biomolecular computing. We provide DNA algorithms based on the sticker model to compute all k-cliques, independent k-sets, Hamiltonian paths, and Steiner trees with respect to a given edge or vertex set. The algorithms determine not merely the existence of a solution but yield all solutions (if any). For an undirected graph with n vertices and m edges, the running time of the algorithms is linear in n+ m. For this, the sticker algorithms make use of small combinatorial input libraries instead of commonly used large libraries. The described algorithms are entirely theoretical in nature. They may become very useful in practice, when further advances in biotechnology lead to an efficient implementation of the sticker model.

  11. Measurement of the NP Elastic Cross Section by Neutron Transmission

    NASA Astrophysics Data System (ADS)

    Daub, Brian; Kovash, Michael; Henzl, Vladimir; Shoniyozov, Khayrullo

    2010-11-01

    There are very few previous measurements of the cross section for neutron-proton elastic scattering at energies between 200 and 500 keV. To improve this situation, we used a pulsed proton beam from the Van de Graaff accelerator at the University of Kentucky to produce 200-800 keV neutrons via the ^7Li(p,n)^7Be reaction. We determined the total n-p elastic cross section by measuring the transmission of the neutron beam in samples of CH2 and carbon, using a BC501 liquid scintillator. The cross section obtained by taking ratios between normalized sample-in and sample-out yields is independent of both detector efficiency and dead time.

  12. np Elastic-scattering experiments with polarized neutron beams

    SciTech Connect

    Chalmers, J.S.; Ditzler, W.R.; Hill, D.; Hoftiezer, J.; Johnson, K.; Shima, T.; Shimizu, H.; Spinka, H.; Stanek, R.; Underwood, D.

    1985-01-01

    Measurements of the spin transfer parameters, K/sub NN/ and K/sub LL/, at 500, 650, and 800 MeV are presented for the reaction p-vector d ..-->.. n-vector pp at 0/sup 0/. The data are useful input to the NN data base and indicate that the quasi-free charge exchange (CEX) reaction is a useful mechanism for producing neutrons with at least 40% polarization at energies as low as 500 MeV. Measurements of np elastic scattering observables C/sub LL/ and C/sub SL/ covering 35/sup 0/ to 172/sup 0/ are performed using a polarized neutron beam at 500, 650, and 800 MeV. Preliminary results are presented. 3 refs., 6 figs.

  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. NMR Investigations of Nitrophorin 2 Belt Side Chain Effects on Heme Orientation and Seating of Native N-terminus NP2 and NP2(D1A)

    PubMed Central

    Muthu, Dhanasekaran; Shokhireva, Tatiana K.; Garrett, Sarah A.; Goren, Allena M.; Zhang, Hongjun

    2014-01-01

    Nitrophorin 2, one of the four NO–storing and –releasing proteins found in the saliva of the blood-sucking bug Rhodnius prolixus, has a more ruffled heme and a high preference for a particular heme orientation (B), compared to those of NP1 and NP4, which show no preference (A:B ~ 1:1), suggesting that it fits more tightly in the β-barrel protein. In this work we have prepared a series of “Belt” mutants of NP2(D1A) and (ΔM0)NP2 aimed at reducing the size of aromatic or other residues that surround the heme, and investigated them as the high-spin aqua and low-spin N-methylimidazole (NMeIm) complexes. The “Belt” mutants included Y38A, Y38F, F42A, F66A, Y85A, Y85F, Y104A, I120T and a triple mutant of NP2(D1A), the F42L,L106F,I120T mutant. Although I120 has been mainly considered to be a distal pocket residue, the CδH3 of I120 lies directly above the heme 3-methyl, at 2.67 Å, of heme orientation B, or 2-vinyl of A, and it thus plays a role as a “Belt” mutant, a role that turns out to be extremely important in creating the strong favoring of the B heme orientation (A:B = 1:14) for NP2(D1A) or 1:12 for (ΔM0)NP2. The results show that the 1D 1H NMR spectra of the high-spin forms are quite sensitive to changes in the shape of the heme binding cavity. The single mutation I120T eliminates the favorability of the B heme orientation by producing a heme A:B orientation of 1:1, while the single mutation F42A reverses the heme orientation from A:B = 1:14 seen for NP2(D1A) to 10:1 for NP2(D1A,F42A). The most extreme ratio was found for the triple mutant of NP2(D1A), NP2(D1A,F42L,L105F,I120T), in which A:B ~25:1, a ΔG change of about −3.5 kcal/mol or −14.1 kJ/mol with respect to NP2(D1A). The seating of the heme is modified as well in that mutant and several others, by rotations of the heme by up to 4° from the seating observed in NP2(D1A), in order to relieve steric interactions between a vinyl β-carbon and a protein side chain, or to fill a cavity

  16. 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

  17. Directed Hierarchical Assemblies of Nanoparticles in Thin Films

    NASA Astrophysics Data System (ADS)

    Xu, Ting

    2011-03-01

    Controlling nanoparticle (NP) assemblies in thin films will enable one to capitalize on the unique properties of NPs so as to generate functional devices, such as hybrid photovoltaic, capacitors and optical devices. To this end, it is mandatory to control the macroscopic alignment of NP assemblies and inter-particle ordering with high precision to achieve a specific property. Recently, we described a new approach to assemble NPs over multiple length scales by combining small molecules with block copolymers (BCPs). Small molecules that favorably interact with NP ligands mediate polymer-NP interactions and solublize the NPs within the BCP microdomains. The small molecules also direct the spatial distribution of NPs within the BCP microdomains with exquisite precision. In the bulk, NPs were shown to readily assemble into ordered 1-D, 2-D and 3-D arrays. I will discuss our recent studies on directed hierarchical assemblies of NPs in thin films. Specifically I will focus on how to manipulate the macroscopic alignment and long-range ordering of NPs and generating NP superlattice within the BCP microdomains. Supported by NSF-DMR, ONR-YIP and DOE-BES.

  18. ΔNp63 intronic miR-944 is implicated in the ΔNp63-mediated induction of epidermal differentiation

    PubMed Central

    Kim, Kyu-Han; Cho, Eun-Gyung; Yu, Seok Jong; Kang, Hyojin; Kim, Yoon-Jin; Kim, Sang Hoon; Lee, Tae Ryong

    2015-01-01

    ΔNp63 is required for both the proliferation and differentiation of keratinocytes, but its role in the differentiation of these cells is poorly understood. The corresponding gene, TP63, harbors the MIR944 sequence within its intron. However, the mechanism of biogenesis and the function of miR-944 are unknown. We found that miR-944 is highly expressed in keratinocytes, in a manner that is concordant with that of ΔNp63 mRNA, but the regulation of miR-944 expression under various conditions did not correspond with that of ΔNp63. Bioinformatics analysis and functional studies demonstrated that MIR944 has its own promoter. We demonstrate here that MIR944 is a target of ΔNp63. Promoter analysis revealed that the activity of the MIR944 promoter was markedly enhanced by the binding of ΔNp63, which was maintained by the supportive action of AP-2 during keratinocyte differentiation. Our results indicated that miR-944 biogenesis is dependent on ΔNp63 protein, even though it is generated from ΔNp63 mRNA-independent transcripts. We also demonstrated that miR-944 induces keratin 1 and keratin 10 expression by inhibiting ERK signaling and upregulating p53 expression. Our findings suggested that miR-944, as an intronic miRNA and a direct target of ΔNp63, contributes to the function of ΔNp63 in the induction of epidermal differentiation. PMID:26202967

  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. 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.

  1. DP-Complete Problems Derived from Extremal NP-Complete Properties

    NASA Astrophysics Data System (ADS)

    Cao, Yi; Culberson, Joseph; Stewart, Lorna

    In contrast to the extremal variants of coNP-complete problems, which are frequently DP-complete, many extremal variants of NP-complete problems are in P. We investigate the extremal variants of two NP-complete problems, the extremal colorability problem with restricted degree and the extremal unfrozen non-implicant problem, and show that both of them are DP-complete.

  2. THE AGS ELECTROSTATIC SEPTUM.

    SciTech Connect

    HOCK,J.RUSSO,T.GLEN,J.BROWN,K.

    2003-05-12

    The previous slow beam extraction electro static septum in the AGS was designed in 1981. Research documented at the Fermi Laboratory was used as the base line for this design. The septum consisted of a ground plane of .002 inch diameter wire tungsten-rhenium alloy (75%W 25%Re) with a hollow welded titanium cathode assembly. The vacuum chamber is stationary and the septum is moved with a pair of high vacuum linear feed throughs. After years of beam time, the frequency of failures increased. The vacuum system design was poor by today's standards and resulted in long pump down times after repairs. The failures ranged from broken septum wires to a twisted cathode. In addition to the failures, the mechanical drive system had too much backlash, making the operating position difficult to repeat. The new septum needed to address all of these issues in order to become a more reliable septum.

  3. EPIDAUROS Biotechnologie AG.

    PubMed

    Arnold, Hans-Peter; Kluge, Peter; Mauch, Simon

    2005-07-01

    EPIDAUROS Biotechnologie AG is a leading provider of pharmacogenetic consulting, genotyping and research services to the international pharmaceutical and biotechnology industries, contract research organizations and healthcare providers. The company's mission is to improve safety, efficacy and predictability in drug development and drug therapy. EPIDAUROS determines its customers' needs in the field of pharmacogenetics using an in-depth consultancy process. The development and conduct of genotyping assays for drug-metabolizing enzymes, drug transporters and drug targets (for example, receptors)--all performed under stringent quality standards--are a major activity at EPIDAUROS. The company offers its research services to academic and industrial partners for the development of innovative diagnostic solutions by using its intellectual property. PMID:16014003

  4. 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. PMID:25641914

  5. AgH, Ag/sub 2/, and AgO revisited: Basis set extensions

    SciTech Connect

    Martin, R.L.

    1987-05-01

    An extended basis set has been developed for Ag which significantly improves the agreement between theoretical and experimental spectroscopic parameters for AgH, AgO, and Ag/sub 2/. The major improvement comes about as a result of the improved treatment of electron correlation in the Ag d shell upon the introduction of f functions. Their inclusion produces very slight differences at the SCF level, but significant reductions in r/sub e/ and increases in ..omega../sub e/ and D/sub e/ in the Mo-dash-barller--Plesset perturbation theory expansion. At the MP4(SDTQ) level, typical results are 0.02 A too long for r/sub e/, 4% too low for ..omega../sub e/, and 10 kcal too small for D/sub e/. From a pragmatic standpoint, MP2 give results very similar to this at a much reduced level of effort.

  6. Plasma Immersion Ion Implantation Applied To N+P Junction Realisation In 4H-SiC

    NASA Astrophysics Data System (ADS)

    Ottaviani, Laurent; Biondo, Stéphane; Daineche, Rachid; Palais, Olivier; Milesi, Frédéric; Duchaine, Julian; Torregrosa, Frank

    2011-01-01

    This paper focuses on the process giving rise to Nitrogen introduction into SiC p-type epitaxial layers. Standard ion implantation and PULSION™ processes are performed at two distinct energies (700 eV and 7 keV), followed by an annealing at 1600 °C in a furnace specifically adapted to SiC material, aiming at creating thin n+p junctions. The doping profiles issued from the implantations show an important channeling effect for all samples. Surface roughness and Nitrogen activation after annealing are studied using AFM and Micro-Four Point Probe means, respectively. A better surface morphology is found on plasma-implanted samples, with a higher sheet resistance (in comparison with standard samples) which could either be related to a lower implanted dose and/or to a lower dopant activation.

  7. 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

  8. 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.

  9. 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.

  10. Perspectives for photonuclear research at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility

    NASA Astrophysics Data System (ADS)

    Filipescu, D.; Anzalone, A.; Balabanski, D. L.; Belyshev, S. S.; Camera, F.; La Cognata, M.; Constantin, P.; Csige, L.; Cuong, P. V.; Cwiok, M.; Derya, V.; Dominik, W.; Gai, M.; Gales, S.; Gheorghe, I.; Ishkhanov, B. S.; Krasznahorkay, A.; Kuznetsov, A. A.; Mazzocchi, C.; Orlin, V. N.; Pietralla, N.; Sin, M.; Spitaleri, C.; Stopani, K. A.; Tesileanu, O.; Ur, C. A.; Ursu, I.; Utsunomiya, H.; Varlamov, V. V.; Weller, H. R.; Zamfir, N. V.; Zilges, A.

    2015-12-01

    The perspectives for photonuclear experiments at the new Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility are discussed in view of the need to accumulate novel and more precise nuclear data. The parameters of the ELI-NP gamma beam system are presented. The emerging experimental program, which will be realized at ELI-NP, is presented. Examples of day-one experiments with the nuclear resonance fluorescence technique, photonuclear reaction measurements, photofission experiments and studies of nuclear collective excitation modes and competition between various decay channels are discussed. The advantages which ELI-NP provides for all these experiments compared to the existing facilities are discussed.

  11. 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

  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. Enhancement of Processability and Electrical Resistance by Use of Ag-Based Composite Inks Containing Ultrafine SAC305 Alloy Nanoparticles

    NASA Astrophysics Data System (ADS)

    Shin, Yong Moo; Kim, Hyun-Jin; Jang, Seok Pil; Lee, Jong-Hyun

    2014-09-01

    We propose use of Ag/Sn-3.0 (wt.%) Ag-0.5 Cu (SAC305) composite ink to reduce sintering temperature, sintering time, and material costs. The SAC305 nanoparticle (NP) surfaces were not capped by any stabilizers, which are detrimental to the resistivity of the sintered tracks. Compared with commercial pure Ag ink, use of Ag/3.2 (vol.%) SAC305 composite ink containing ultrafine SAC305 NPs resulted in outstandingly enhanced processability, enabling faster sintering at low temperatures. The average sheet resistance of composite ink samples sintered for 25 min at 170°C was as low as 0.011 Ω/□, comparable with that of a pure Ag sample sintered for over 30 min at 220°C. The morphology and the differential scanning calorimetry curves enabled explanation of the changes in the sintering behavior and sheet resistance. The Ag/SAC305 clusters in the composite ink sintered at 170°C grew, on average, to ~201.1-226.1 nm as a result of faster local liquid-phase sintering, and most of the Ag particles were mutually linked, dramatically changing the microstructure.

  14. Improvement of polypyrrole nanowire devices by plasmonic space charge generation: high photocurrent and wide spectral response by Ag nanoparticle decoration.

    PubMed

    Lee, S-H; Bae, J; Lee, S W; Jang, J-W

    2015-11-01

    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 ∼ V(m)) 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. PMID:26413791

  15. Nb3Sn multifilamentary superconductors fabricated through a diffusion reaction between Nb and Ag-Sn alloys

    NASA Astrophysics Data System (ADS)

    Matsumoto, G.; Inoue, K.; Kikuchi, A.; Takeuchi, T.; Kiyoshi, T.

    2006-06-01

    Ag-Sn alloy is very attractive for fabricating Nb3Sn wires through diffusion reaction, because Ag-based alloy including a large amount of Sn is ductile. Therefore we investigated the Nb3Sn formation through the diffusion reaction between Nb and Ag-Sn alloys. With using Ag-9 at% Sn fcc phase, Ag-12 at% Sn ζ phase, and Ag-24at% Sn epsilon phase alloys, we fabricated single-core, 200-core, and 40000-core composite wires with Nb matrix and Ag-Sn alloy cores. With increase of Sn content in Ag-Sn alloys, the obtained superconducting properties of heat treated composite wires were improved. Tc and Bc2(4.2 K) for the Nb/Ag-Sn are similar to those for the Nb/Cu-Sn. However, the Ic values are relatively small, due to the formed very thin Nb3Sn layers. Ag is apparently not so effective to increase the formation rate of Nb3Sn layer as Cu. We obtained very interesting results by making the 200-core and 40000-core wires, which show the improved Tc and Bc2(4.2 K) by 0.5-1 K and 2-5 T, respectively. From 10 to 500 times larger Ic(4.2 K) were also obtained for the multifilamentary wires.

  16. 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

  17. Fabrication of an organic field effect transistor using nano imprinting of Ag inks and semiconducting polymers

    NASA Astrophysics Data System (ADS)

    Hu, PingAn; Li, Kun; Chen, Weilin; Peng, Li; Chu, Daping; O'Neill, William

    2010-07-01

    A simple and cheap procedure for flexible electronics fabrication was demonstrated by imprinting metallic nanoparticles (NPs) on flexible substrates. Silver NPs with an average diameter of 10 nm were prepared via an improved chemical approach and Ag Np ink was produced in α-terpineol with a concentration up to 15%. Silver micro/nanostructures with a dimension varying from nanometres to microns were produced on a flexible substrate (polyimide) by imprinting the as-prepared silver ink. The fine fluidic properties of an Ag NP/α-terpineol solution and low melting temperatures of silver nanoparticles render a low pressure and low temperature procedure, which is well suited for flexible electronics fabrication. The effects of sintering and mechanical bending on the conductivity of imprinted silver contacts were also investigated. Large area organic field effect transistors (OFET) on flexible substrates were fabricated using an imprinted silver electrode and semiconducting polymer. The OFET with silver electrodes imprinted from our prepared oleic acid stabilized Ag nanoparticle ink show an ideal ohmic contact; therefore, the OFET exhibit high performance (Ion/Ioff ratio: 1 × 103; mobility: 0.071 cm2 V-1 s-1).

  18. Modification of light absorption in thin CuInS2 films by sprayed Au nanoparticles.

    PubMed

    Katerski, Atanas; Kärber, Erki; Acik, Ilona Oja; Dolgov, Leonid; Mere, Arvo; Sildos, Ilmo; Mikli, Valdek; Krunks, Malle

    2014-12-01

    The chemical spray pyrolysis method was used to deposit CuInS2 (CIS) thin films and Au nanoparticles (NPs) in two configurations: glass/Au-NP layer covered with CuInS2 film (Au-NP/CIS) and glass/CuInS2 films covered with Au-NP layer (CIS/Au-NP). According to X-ray diffraction (XRD), the spray of 2 mM HAuCl4 aqueous solution with a volume of 2.5 to 15 ml onto a glass substrate at 340°C results in metallic Au nanoparticles with a similar mean crystallite size in the range of 30 - 38 nm. The mean crystallite sizes remain in the range of 15 - 20 nm when grown onto a CIS film. The prepared films show plasmonic light absorption with increasing intensity in the spectral range of 500- 800 nm when increasing the volume of HAuCl4 solution sprayed. When compared to bare CIS on glass, the absorptance was increased ca. 4.5 times in the case of glass/Au-NP/CIS and ca. 3 times in the case of glass/CIS/Au-NP configuration. The glass/Au-NP/CIS configuration had an advantage since Au-NP could be embedded without chemically damaging the CIS. PMID:26088996

  19. Third-order optical nonlinearity studies of bilayer Au/Ag metallic films

    NASA Astrophysics Data System (ADS)

    Mezher, M. H.; Chong, W. Y.; Zakaria, R.

    2016-05-01

    This paper presents nonlinear optical studies of bilayer metallic films of gold (Au) and silver (Ag) on glass substrate prepared using electron beam evaporation. The preparation of Au and Ag nanoparticles (NPs) on the substrate involved the use of electron beam deposition, then thermal annealing at 600 °C and 270 °C, respectively, to produce a randomly distributed layer of Au and a layer of Ag NPs. Observation of field-effect scanning electron microscope images indicated the size of the NPs. Details of the optical properties related to peak absorption of surface plasmon resonance of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear absorption and nonlinear refraction of the fabricated NP layers. The third-order nonlinear refractive index coefficients for Au and Ag are (-9.34 and  -1.61)  ×  10-11 cm2 W-1 given lower n 2, in comparison with bilayer (Au and Ag) NPs at  -1.24  ×  10-10 cm2 W-1. The results show bilayer NPs have higher refractive index coefficients thus enhance the nonlinearity effects.

  20. Ultrasmooth and thermally stable silver-based thin films with subnanometer roughness by aluminum doping.

    PubMed

    Gu, Deen; Zhang, Cheng; Wu, Yi-Kuei; Guo, L Jay

    2014-10-28

    Rough surface and poor stability of ultrathin Ag films limit their applications in nanophotonic and optoelectronic devices. Here, we report an approach for fabricating ultrasmooth and thermally stable Ag-based thin films on SiO2/Si substrates by Al-doping. The effect of Al-doping on the surface morphology and stability of ultrathin Ag films at room temperature and elevated temperature was investigated. The 15 nm Al-doped Ag films with an Al atomic concentration of 4% have a root-mean-square roughness as low as 0.4 nm. The smooth surface morphology is maintained even after 300 °C annealing in N2. Al-doping enhances the nuclei density of films. Moreover, a capping layer spontaneously formed over the Al-doped Ag films restrains the surface diffusion and mass transportation of Ag atoms. Therefore, Al-doping induces ultrathin Ag films with highly stable and ultrasmooth surface morphology. PMID:25211394

  1. 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. PMID:26684078

  2. Recrystallization of Cu-poor CuInS{sub 2} assisted by metallic Cu or Ag

    SciTech Connect

    Rodriguez-Alvarez, Humberto; Mainz, Roland; Marsen, Bjoern; Schock, Hans-Werner

    2010-04-15

    We monitor the recrystallization of Cu-poor CuInS{sub 2} thin films assisted by pure Cu or pure Ag by means of real-time synchrotron-based polychromatic X-ray diffraction. In both cases a new microstructure is formed accompanied by an increase in grain size. In the case of Cu, the onset temperature of the thin-film recrystallization is higher than 370 deg. C. In the case of Ag, the thin-film recrystallization comes to an end at 270 deg. C. The Ag-assisted recrystallization occurs in the presence of the body-centered cubic beta-Ag{sub 2}S phase. We find that domain growth and diffusion of silver into the film occur simultaneously. - Graphical abstract Keywords: Recrystallization; Thin-film solar cells; Energy-dispersive x-ray diffraction: In-situ monitoring by means of energy-dispersive X-ray diffraction of the thin-film recrystallization of Cu-poor CuInS{sub 2} assisted by metallic Ag.

  3. 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.

  4. 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.

  5. NMR investigation of Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Son, Kwanghyo; Jang, Zeehoon

    2013-01-01

    109Ag nuclear magnetic resonance (NMR) and relaxation measurements have been performed on two powder samples of Ag nanoparticles with average sizes of 20 nm and 80 nm. The measurements have been done in an external field of 9.4 T and in the temperature range 10 K < T < 280 K. The 109Ag NMR spectra for both samples have close to Lorentzian shapes and turn out to be mixtures of homogeneous and inhomogeneous lines. The linewidth Δ ν at room temperature is 1.3 kHz for both samples and gradually increases with decreasing temperature. Both the Knight shift ( K) and the nuclear spin-lattice relaxation rate (1/ T 1) are observed to be almost identical to the values reported for the bulk Ag metal, whereby the Korringa ratio R(= K 2 T 1 T/S) is found to be 2.0 for both samples in the investigated temperature range.

  6. 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

  7. N/P ratio of nutrient uptake in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Wan, Z.; Jonasson, L.; Bi, H.

    2011-06-01

    The N/P ratio of nutrient uptake, i.e., the ratio of dissolved inorganic nitrogen (DIN) to dissolved inorganic phosphorus (DIP) taken by primary producers, varies in different basins and in different seasons in the Baltic Sea. The N/P ratio of nutrient alteration fore and after spring blooms is not same as the N/P ratio of nutrient uptake, but the former can be regarded as an indicator for the later in the Baltic Sea. Based on the observed N/P ratio of nutrient alteration, we hypothesize a non-Redfield N/P ratio of nutrient uptake. The 3D-ecosystem model ERGOM coupled with the circulation model DMI-BSHcmod was used to test the hypothesis. When the Redfield ratio was used in the model, the DIP surplus after spring blooms was too high and resulted in the overly growth of cyanobacteria and too much nitrogen fixation. When the non-Redfield ratio was used in the model, the corresponding problem tended to disappear. In summary, we show that: (1) the Redfield N/P ratio of nutrient uptake in the Baltic Sea tends to be too high; (2) a lower N/P ratio 10:1 appears to work better than the Redfield value; and (3) the N/P ratio of nutrient uptake in the Baltic Proper during spring blooms is around 6:1.

  8. Np(v) complexation with carbonate in aqueous solutions studied by spectrophotometric titration at various temperatures.

    PubMed

    Yang, Suliang; Zhao, Yaping; Tian, Guoxin

    2016-02-14

    The complexation of neptunium(v) with carbonate has been studied at temperatures from 10 to 70 °C in 0.1 M LiClO4 by spectrophotometry. Three NpO2(+)-CO3(2-) complex species, NpO2(CO3)n((2n-1)-) (n = 1, 2, 3), are identified and the stability constants are calculated by using the absorption spectra in the near-IR region collected from titrations at varying temperatures. The enthalpies and entropies are calculated with van't Hoff equations in the temperature range of 10 to 70 °C, indicating that the formation of all NpO2(+)-CO3(2-) complexes is mainly entropy driven. The structures of the NpO2(+)-CO3(2-) complex species in aqueous solutions are also reviewed. Based on the molar absorptivity of Np(v) in the near-IR region the structure of NpO2(CO3)2(3-) is re-constructed as NpO2(CO3)2(H2O)(3-)of low symmetry but not as NpO2(CO3)2(H2O)2(3-)of high symmetry as suggested in a previous study. PMID:26744184

  9. Ambiguity-Avoidance: A Universal Constraint on Extraction from NP Sequences.

    ERIC Educational Resources Information Center

    Sweetser, Eve E.

    This research deals with how extraction rules are constrained in cases where their unconstrained application would give rise to semantic ambiguity. Of particular concern is the application of extraction rules to noun phrases (NP's) where word order is the only indication of the different syntactic functions of two adjacent NP's. Samples from…

  10. 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

  11. 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

  12. CarbAcineto NP Test for Rapid Detection of Carbapenemase-Producing Acinetobacter spp.

    PubMed Central

    Dortet, Laurent; Poirel, Laurent; Errera, Caroline

    2014-01-01

    Multidrug-resistant Acinetobacter baumannii isolates, particularly those that produce carbapenemases, are increasingly reported worldwide. The biochemically based Carba NP test, extensively validated for the detection of carbapenemase producers among Enterobacteriaceae and Pseudomonas spp., has been modified to detect carbapenemase production in Acinetobacter spp. A collection of 151 carbapenemase-producing and 69 non-carbapenemase-producing Acinetobacter spp. were tested using the Carba NP test and a modified Carba NP protocol (the CarbAcineto NP test) in this study. The CarbAcineto NP test requires modified lysis conditions and an increased bacterial inoculum compared to those of the original Carba NP test. The Carba NP test detects metallo-β-lactamase producers but failed to detect the production of other carbapenemase types among Acinetobacter spp. In contrast, the newly designed CarbAcineto NP test, which is rapid and reproducible, detects all types of carbapenemases with a sensitivity of 94.7% and a specificity of 100%. This cost-effective technique offers a reliable and affordable technique for identifying carbapenemase production in Acinetobacter spp., which is a marker of multidrug resistance in those species. Its use will facilitate the recognition of these carbapenemases and prevent their spread. PMID:24759709

  13. Investigation of noble metal substrates and buffer layers for BiSrCaCuO thin films

    NASA Astrophysics Data System (ADS)

    Matthiesen, M. M.; Rubin, L. M.; Williams, K. E.; Rudman, D. A.

    Noble metal buffer layers and substrates for Bi2Sr2CaCu2O8 (BSCCO) films were investigated using bulk ceramic processing and thin-film techniques. Highly oriented, superconducting BSCCO films were fabricated on polycrystalline Ag substrates and on Ag/MgO and Ag/YSZ structures. Such films could not be produced on Au or Pt substrates under any annealing conditions. In addition, superconducting BSCCO films could not be produced on Ag/Al2O3, Ag/SiO2/Si, or Ag/(Haynes 230 alloy) structures using high annealing temperatures (870 C). However, oriented although poorly connected, superconducting BSCCO films were fabricated on Ag/Al2O3 structures by using lower annealing temperatures (820 C). Once lower processing temperatures are optimized, Ag may be usable as a buffer layer for BSCCO films.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. Strong magnetization damping induced by Ag nanostructures in Ag/NiFe/Ag trilayers

    NASA Astrophysics Data System (ADS)

    Ley Domínguez, D.; da Silva, G. L.; Rodríguez-Suárez, R. L.; Rezende, S. M.; Azevedo, A.

    2013-07-01

    Ferromagnetic resonance has been used to investigate the magnetization relaxation in trilayers of Ag(t)/NiFe(10 nm)/Ag(t), sputter deposited on Si(001) where the thickness of the Ag layer varied from 0 nm to 24 nm. In the first stages of formation, the Ag layers form islands that work as mold to imprint defects or inhomogeneities on the NiFe film surface. The magnetic inhomogeneities and defects imprinted on the surface of the NiFe film act as extrinsic sources of magnetization relaxation in addition to the intrinsic Gilbert damping mechanism. Weak inhomogeneities are associated to the two-magnon scattering source and the strong inhomogeneities are associated to the fluctuations of the local magnetization. By adding the three different sources of magnetization damping, we were able to explain the azimuthal dependence of the ferromagnetic resonance linewidth.

  1. Antimicrobial activity of thin solid films of silver doped hydroxyapatite prepared by sol-gel method.

    PubMed

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

    2014-01-01

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

  2. Evaluation of Ag containing hydroxyapatite coatings to the Candida albicans infection.

    PubMed

    Ciuca, S; Badea, M; Pozna, E; Pana, I; Kiss, A; Floroian, L; Semenescu, A; Cotrut, C M; Moga, M; Vladescu, A

    2016-06-01

    In this research work, the synthesis of Ag doped hydroxyapatite coatings for dental or orthopedic implants was performed. The main goal was to determine the influence of Ag content on the roughness and antimicrobial performance of the prepared thin films. The films were deposited on Ti6Al4V alloy by means of RF magnetron sputtering. Those coatings were characterized by X-ray diffraction (XRD) and 3D surface profilometry. The antifungal activity after 1 and 7days of culture was evaluated in the presence of Candida albicans (ATCC - 10231). The increase of Ag content increased roughness and reduced the antifungal activity. The results showed that the Ag doped hydroxyapatite coatings can be a potential solution for the improvement of the antifungal activities of Ti based alloy. PMID:27021660

  3. Preparation and surface enhanced Raman scattering behavior of Ag-coated C60 nanoclusters

    NASA Astrophysics Data System (ADS)

    Kang, Shi-Zhao; Yin, Die-er; Li, Xiangqing; Mu, Jin

    2013-12-01

    Ag-coated C60 nanoclusters were prepared and characterized with X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption isotherm measurement. The Ag-coated C60 nanoclusters were assembled on the glass substrate to form a thin film using the layer-by-layer technique. Meanwhile, the surface enhanced Raman scattering (SERS) of musk xylene adsorbed on the film of Ag-coated C60 nanoclusters was explored. The results indicated that the film of Ag-coated C60 nanoclusters was a unique SERS-active substrate with a detection limit of 10-9 mol L-1 for musk xylene. Furthermore, the surface enhanced mechanisms were discussed preliminarily.

  4. Enhanced absorption of Ag diamond-type nanoantenna arrays

    NASA Astrophysics Data System (ADS)

    Yuan, Zong-heng; Li, Xiao-nan; Guo, Ya-dong; Huang, Jing

    2015-01-01

    The optical metal nanoantenna on thin film solar cell is effective to enhance light absorption. In this paper, the diamond-type Ag nanoantenna arrays are proposed for increasing the efficiency of solar cells by localized surface plasmons resonance (LSPR). The effect of metal nanoantenna on the absorption enhancement is theoretically investigated by the finite difference time domain (FDTD) method. Broadband absorption enhancements in both visible and near-infrared regions are demonstrated in case of solar cell with diamond-type Ag nanoantennas. The spectral response is manipulated by geometrical parameters of the nanoantennas. The maximum enhancement factor of 1.51 for solar cell is obtained. For comparison, the other three nanoantennas are also analyzed. The results show that the solar cell with optimized diamond-type nanoantenna arrays is more efficient in optical absorption.

  5. CONTINUOUS EXTRACTED BEAM IN THE AGS FAST EXTERNAL BEAM LINE.

    SciTech Connect

    GLENN,J.W.; TSOUPAS,N.; BROWN,K.A.; BIRYUKOV,V.M.

    2001-06-18

    A method to split off a few percent of the 6 x 10{sup 13} AGS beam delivered to the Slow External Beam (SEB) lines and send it down the Fast External Beam line (FEB) has been developed. The mission is to feed a counter experiment off the FEB that directly measures the neutrino mass using the muon storage ring. The use of normal thin septum splitters would have an excessive loss overhead and been optically difficult. The AGS Slow Extraction uses a third integer resonance with sextuple strength so the resonance width is a few percent of the beam width. This results in a low density tail which will be clipped by a bent crystal and deflected into the FEB channel. This clipping off of the tail should reduce losses in the SEB transport line. Details of modeled orbits, particle distribution and extraction trajectories into and out off the crystal will be given.

  6. p-Carbon CNI polarimetry in the AGS and RHIC.

    SciTech Connect

    Huang,H.; Alekseev, I.; Bazilevsky, A.; Bravar, A.; Bunce, G.; Dhawan, S.; Gill, R.; Makdisi, Y.; Morozov, B.; Roser, T.; Steski, D.; Sivertz, M.; Svirida, D.; Wood, J.; Yip, K.; Zelenski, A.

    2008-06-23

    Proton polarization measurements in the AGS (Alternate Gradient Synchrotron) and RHIC (Relativistic Heavy Ion Collider) are based on proton-carbon(pC) and proton-proton elastic scattering in the Coulomb Nuclear Interference (CNI) region. The CNI polarimeters are the essential tools for polarized proton acceleration setup and operation. High intensity recoil nuclei from the scattering of the circulating proton beam in the thin carbon target is efficiently utilized in the silicon strip detectors and data acquisition system, which is capable to analyze the event rate up to a few millions/second. This makes it possible for the fast, practically non-destructive polarization measurements. The polarization measurement on the beam energy ramp was implemented in AGS and RHIC, providing locations of polarization losses. Polarimeter operation in the scanning mode also gives polarization profile and beam profile (including bunch by bunch values for the later one). This paper summarizes the recent modifications. Results of polarization measurements are also discussed.

  7. Concurrent NP-HPTLC Determination of Shikonin and β,β-Dimethylacryl Shikonin in Arnebia benthamii.

    PubMed

    Katoch, Preeti; Rana, Shalika; Kumar, Dinesh; Kumar, Shiv; Bhushan, Shashi

    2016-09-01

    Naphthoquinones are important class of molecules found as a natural red color pigments in roots of Arnebia benthamii (Wall. ex G. Don) L M. Johnston. The aim of present investigation is to develop and validates a simple, cost-effective and reliable method for quantification of these compounds. Therefore, a normal phase-high performance thin-layer chromatography (NP-HPTLC) method for concurrent determination of shikonin and β,β-dimethylacryl shikonin in A. benthamii was established. Method development of naphthoquinones in the methanol extract was done using hexane-ethyl acetate-methanol (40:7.5:2.5, v/v/v) solvent system at 520 nm. The developed method showed good band separation for shikonin (Rf, 0.37) and β,β-dimethylacryl shikonin (Rf, 0.58). The linearity ranged between 100 and 8,000 ng spot(-1) with an average recovery of >97% in both cases. The results showed reproducible intraday and interday precision (<2.0% RSD) in quantification of naphthoquinones. The limits of detection are 12.96 and 14.65 ng spot(-1) while the limits of quantification are 39.27 and 44.39 ng spot(-1) for shikonin and β,β-dimethylacryl shikonin, respectively. The developed method is reliable, fast, easy to follow and economic in concurrent assessment of shikonin and β,β-dimethylacryl shikonin in A. benthamii root samples. In addition, it seems to be first report for identification and quantification of β,β-dimethylacryl shikonin from the A. benthamii. PMID:27278171

  8. Synthesis of Ag(2) S-Ag nanoprisms and their use as DNA hybridization probes.

    PubMed

    Liu, Bing; Ma, Zhanfang

    2011-06-01

    A simple synthetic route to prepare Ag(2) S-Ag nanoprisms consists of the facile addition of Na(2) S to a solution of triangular Ag nanoprisms. The resulting Ag(2) S-Ag nanoparticles are more stable in solution than the original Ag nanoprisms, and two surface plasmon resonance (SPR) bands of the original Ag nanoprisms still remain. In addition, the SPR bands of the Ag(2) S-Ag nanoprisms are tunable over a wide range. The Ag(2) S-Ag nanoprisms can be directly bioconjugated via well-established stable Ag(2) S surface chemistry with readily available sulfur coupling agents. The nanoprisms are used in the hybridization of functionalized oligonucleotides, and show promise as probes for future biosensing applications. PMID:21538868

  9. 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.

  10. Hafnium dioxide as a passivating layer and diffusive barrier in ZnO/Ag Schottky junctions obtained by atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Krajewski, Tomasz A.; Luka, Grzegorz; Gieraltowska, Sylwia; Zakrzewski, Adam J.; Smertenko, Petro S.; Kruszewski, Piotr; Wachnicki, Lukasz; Witkowski, Bartlomiej S.; Lusakowska, Elzbieta; Jakiela, Rafal; Godlewski, Marek; Guziewicz, Elzbieta

    2011-06-01

    This paper reports on ZnO/Ag Schottky junctions obtained by the low temperature atomic layer deposition process. Introducing the thin (from 1.25 to 7.5 nm) layer of hafnium dioxide between the ZnO layer and evaporated Ag Schottky contact improves the rectification ratio to about 105 at 2V. For the ZnO/Ag junctions without the HfO2 interlayer, the rectification ratio is only 102. We assign this effect to the passivation of ZnO surface accumulation layer that is reported for ZnO thin films.

  11. Study of the oxygen transport through Ag (110), Ag (poly), and Ag 2.0 Zr

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Wu, D.; Davidson, M. R.; Hoflund, Gar B.

    1992-01-01

    The transport of oxygen through high-purity membranes of Ag (110), Ag (poly), Ag (nano), and Ag 2.0 Zr has been studied by an ultrahigh vacuum permeation method over the temperature range of 400-800 C. The data show that there are substantial deviations from ordinary diffusion-controlled transport. A surface limitation has been confirmed by glow-discharge studies where the upstream O2 supply has been partially converted to atoms, which, for the same temperature and pressure, gave rise to over an order of magnitude increase in transport flux. Further, the addition of 2.0 wt percent Zr to the Ag has provided increased dissociative adsorption rates, which, in turn, increased the transport flux by a factor of 2. It was also observed that below a temperature of 630 C, the diffusivity exhibits an increase in activation energy of over 4 kcal/mol, which has been attributed to trapping of the atomic oxygen and/or kinetic barriers at the surface and subsurface of the vacuum interface. Above 630 C, the activation barrier decreases to the accepted value of about 11 kcal/mol for Ag (poly), consistent with zero concentration at the vacuum interface.

  12. 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. PMID:24433907

  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. 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

  15. Properties of Silver Nanowire/Zinc Oxide Transparent Bilayer Thin Films for Optoelectronic Applications.

    PubMed

    You, Sslimsearom; Park, Yong Seo; Choi, Hyung Wook; Kim, Kyung Hwan

    2015-11-01

    We have investigated electrical, optical and structural properties of silver nanowire (AgNW)/zinc oxide (ZnO) transparent conductive bilayer films for optoelectronic applications. The AgNW/ZnO transparent conductive bilayer films were fabricated using spin-coating and facing target sputtering (FTS) method. The spin-coated the AgNW layer has advantages, such as low resistivity and high transmittance in visible range. However, the spin-coated AgNW layers can be oxidized by natural oxygen. Consequently, the conductivity of AgNW layer was strongly decreased. So, an oxidation prevented layer is necessary. The ZnO thin film layer on the Ag NW layer can be prevented oxidation. In addition, the peeling of spin-coated AgNW layer were prevented the deposited ZnO thin film layer. As the results, the sheet resistance and average transmittance in visible range of AgNW/ZnO transparent bilayer thin films exhibited 34.1 ohm/sq. and 83.46%. PMID:26726570

  16. 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.

  17. 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, Seung-Hoon; Lee, Seung Woo; Jang, Jaw-Won

    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). The photocurrent density is remarkably improved, up to 25.3 times, by the Ag NP decoration onto the PPy NW (PPyAgNPs NW) under blue light 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. Supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (no. 2013K1A3A1A32035429 and 2015R1A1A1A05027681).

  18. The effect of size and size distribution on the oxidation kinetics and plasmonics of nanoscale Ag particles.

    PubMed

    Qi, Hua; Alexson, Dimitri; Glembocki, Orest; Prokes, S M

    2010-05-28

    We employed a simple and effective electroless (EL) plating approach to produce silver nanoparticles (NPs) on bare silicon, on dielectric ZnO nanowires (NWs) and on Si NWs, respectively. The surface stability of the homogeneous Ag NPs formed on the ZnO NW surfaces was investigated by surface enhanced Raman spectroscopy (SERS), which show that the attachment of thiol to the Ag surface can slow down the oxidation process, and the SERS signal remains strong for more than ten days. To further examine the Ag NP oxidation process in air, the oxygen content in the silicon nanowire core/Ag sheath composites was monitored by the energy dispersive x-ray (EDX) method. The amount of oxygen in the system increases with time, indicating the silver NPs were continuously oxidized, and it is not clear if saturation is reached in this time period. To investigate the influence of the Ag NPs size distribution on the oxidation process, the oxygen amount in the NPs formed by EL deposition and e-beam (EB) evaporation on a bare silicon surface was compared. Results indicate a faster oxidation process in the EL formed Ag NPs than those produced by EB evaporation. We attribute this observation to the small diameter of the EL produced silver particles, which results in a higher surface energy. PMID:20431201

  19. The effect of size and size distribution on the oxidation kinetics and plasmonics of nanoscale Ag particles

    NASA Astrophysics Data System (ADS)

    Qi, Hua; Alexson, Dimitri; Glembocki, Orest; Prokes, S. M.

    2010-05-01

    We employed a simple and effective electroless (EL) plating approach to produce silver nanoparticles (NPs) on bare silicon, on dielectric ZnO nanowires (NWs) and on Si NWs, respectively. The surface stability of the homogeneous Ag NPs formed on the ZnO NW surfaces was investigated by surface enhanced Raman spectroscopy (SERS), which show that the attachment of thiol to the Ag surface can slow down the oxidation process, and the SERS signal remains strong for more than ten days. To further examine the Ag NP oxidation process in air, the oxygen content in the silicon nanowire core/Ag sheath composites was monitored by the energy dispersive x-ray (EDX) method. The amount of oxygen in the system increases with time, indicating the silver NPs were continuously oxidized, and it is not clear if saturation is reached in this time period. To investigate the influence of the Ag NPs size distribution on the oxidation process, the oxygen amount in the NPs formed by EL deposition and e-beam (EB) evaporation on a bare silicon surface was compared. Results indicate a faster oxidation process in the EL formed Ag NPs than those produced by EB evaporation. We attribute this observation to the small diameter of the EL produced silver particles, which results in a higher surface energy.

  20. 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. PMID:24388903

  1. 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.

  2. 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.

  3. NP001 regulation of macrophage activation markers in ALS: a phase I clinical and biomarker study.

    PubMed

    Miller, Robert G; Zhang, Rongzhen; Block, Gilbert; Katz, Jonathan; Barohn, Richard; Kasarskis, Edward; Forshew, Dallas; Gopalakrishnan, Vidhya; McGrath, Michael S

    2014-12-01

    This is a phase I, placebo-controlled, single ascending dose safety and tolerability study of NP001 in patients with ALS. NP001 is a novel regulator of inflammatory macrophages and monocytes. As ALS progression is thought to be related to neuroinflammation, an additional objective of the study was to assess the effects of NP001 administration on monocyte activation markers. Thirty-two ALS patients were enrolled and received either placebo (eight) or one of four (six at each dose) ascending single i.v. doses (0.2, 0.8, 1.6 and 3.2 mg/kg NP001). Patients were monitored for safety, and blood monocyte immune activation markers CD16 and HLA-DR were assessed pre- and 24 h post-dosing. Changes from baseline were calculated. Results showed that NP001 was generally safe and well tolerated. Importantly, a single dose of NP001 caused a dose-dependent reduction in expression of monocyte CD16, a marker of monocyte activation/inflammation. Additionally, monocyte HLA-DR expression was also decreased in those patients with elevated values at baseline. In conclusion, these data indicate that NP001 has an acute effect on inflammatory monocytes in ALS patient blood. The potential for modulation of inflammation in the context of ALS disease progression will require further study with long-term follow-up. PMID:25192333

  4. 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.

  5. Mechanistic insights into PEPT1-mediated transport of a novel antiepileptic, NP-647.

    PubMed

    Khomane, Kailas S; Nandekar, Prajwal P; Wahlang, Banrida; Bagul, Pravin; Shaikh, Naeem; Pawar, Yogesh B; Meena, Chhuttan Lal; Sangamwar, Abhay T; Jain, Rahul; Tikoo, K; Bansal, Arvind K

    2012-09-01

    The present study, in general, is aimed to uncover the properties of the transport mechanism or mechanisms responsible for the uptake of NP-647 into Caco-2 cells and, in particular, to understand whether it is a substrate for the intestinal oligopeptide transporter, PEPT1 (SLC15A1). NP-647 showed a carrier-mediated, saturable transport with Michaelis-Menten parameters K(m) = 1.2 mM and V(max) = 2.2 μM/min. The effect of pH, sodium ion (Na(+)), glycylsarcosine and amoxicillin (substrates of PEPT1), and sodium azide (Na(+)/K(+)-ATPase inhibitor) on the flux rate of NP-647 was determined. Molecular docking and molecular dynamics simulation studies were carried out to investigate molecular interactions of NP-647 with transporter using homology model of human PEPT1. The permeability coefficient (P(appCaco-2)) of NP-647 (32.5 × 10(-6) cm/s) was found to be four times higher than that of TRH. Results indicate that NP-647 is transported into Caco-2 cells by means of a carrier-mediated, proton-dependent mechanism that is inhibited by Gly-Sar and amoxicillin. In turn, NP-647 also inhibits the uptake of Gly-Sar into Caco-2 cells and, together, this evidence suggests that PEPT1 is involved in the process. Docking and molecular dynamics simulation studies indicate high affinity of NP-647 toward PEPT1 binding site as compared to TRH. High permeability of NP-647 over TRH is attributed to its increased hydrophobicity which increases its affinity toward PEPT1 by interacting with the hydrophobic pocket of the transporter through hydrophobic forces. PMID:22779445

  6. 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.

  7. 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.

  8. The synthesis and characterization of neptunium hydroxysulfate, Np(OH)/sub 2/SO/sub 4/

    SciTech Connect

    Wester, D.W.; Mulak, J.; Banks, R.; Carnall, W.T.

    1982-11-15

    Neptunium (IV) hydroxysulfate, Np(OH)/sub 2/SO/sub 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.

  9. Conversion-electron experiment to characterize the decay of the /sup 237/Np shape isomer

    SciTech Connect

    Henry, E.A.; Becker, J.A.; Bauer, R.W.; Gardner, D.G.; Decman, D.J.; Meyer, R.A.; Roy, N.; Sale, K.E.

    1987-12-08

    Conversion electrons from the decay of low-lying levels of /sup 237/Np have been measured to detect the population of these levels by gamma-ray decay of the /sup 237/Np shape isomer. Analysis of the 208-keV transition L conversion-electron peak gives an upper limit of about 17 ..mu..b for the population of the 3/2/sup -/ 267-keV level in /sup 237/Np from the shape isomer decay. Model calculations are compared with the measured limit. Improvements are suggested for this experiment. 9 refs., 4 figs.

  10. 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.

  11. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures

    NASA Astrophysics Data System (ADS)

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-11-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au+ ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

  12. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

    PubMed

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-12-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures. PMID:26563266

  13. Contributions of Ag Nanowires to the Photoelectric Conversion Efficiency Enhancement of TiO2 Dye-Sensitized Solar Cells.

    PubMed

    Liu, Yunyu; She, Guangwei; Qi, Xiaopeng; Mu, Lixuan; Wang, Xuesong; Shi, Wensheng

    2015-09-01

    Ag nanowires (AgNWs) were employed in mesoporous TiO2 dye-sensitized solar cells (DSSCs) to enhance the photoelectric conversion efficiency (PCE). The possible reasons for PCE improvement, i.e., improvement in electron transport and light harvesting due to light scattering and plasmonic resonance effect of AgNWs are investigated. Electrochemical impedance spectra (EIS) study proved that addition of AgNWs can enhance the conductivity of TiO2 thin film photoanode, which is an important reason for the increase of photocurrent. Furthermore, through the comparison experiments as well as the UV-Vis absorption and IPCE characterization, contributions of the light scattering and plasmonic resonance effect to the enhancement of light harvest, and thus PCE of the DSSCs were demonstrated. It was found that fast electron transport of AgNWs played more important role for the PCE improvement than the light harvest enhancement due to light scattering and plasmonic effect. Based on these investigations, the AgNWs modified TiO2 thin film DSSCs were optimized. After integrating AgNWs into the photoanode, the photocurrent increased significantly and PCE increased -50% comparing with the pure TiO2-based DSSCs. PMID:26716285

  14. Thin Clouds

    Atmospheric Science Data Center

    2013-04-18

    ... of this montage is a natural-color view of the Caribbean Sea east of the Yucatan Peninsula as seen by MISR's most steeply ... - Thin, feathery clouds of ice crystals over the Caribbean Sea. project:  MISR category:  gallery ...

  15. Covalently-layers of PVA and PAA and in situ formed Ag nanoparticles as versatile antimicrobial surfaces.

    PubMed

    Fragal, Vanessa H; Cellet, Thelma S P; Pereira, Guilherme M; Fragal, Elizângela H; Costa, Marco Antonio; Nakamura, Celso Vataru; Asefa, Tewodros; Rubira, Adley F; Silva, Rafael

    2016-10-01

    The in situ synthesis of silver nanoparticles (AgNPs) within covalently-modified poly(ethylene terephthalate) (PET) films possessing ultra-thin layer of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) is successfully demonstrated. The resulting polymeric films are shown to exhibit antimicrobial activities toward Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and fungus (Candida albicans). To make the films, first PET surfaces were subject to photo-oxidation and subsequent solid-state grafting to attach a PVA layer, followed by a PAA layer. To synthesize the AgNPs inside the films, the PVA and PAA-modified PET was soaked in AgNO3 solution and the polymeric film was modified with the Ag(+) ions via Ag(+)-carboxylate interaction, and then the Ag(+) ions-containing polymer film was subject to either photo-reduction or thermal reduction processes. The PVA and PAA thin layers attached by covalent bonds to the PET surface uniquely promoted not only the in situ synthesis but also the stabilization of AgNPs. The formation of the AgNPs was confirmed by UV-vis spectroscopy or by monitoring the surface plasmon resonance (SPR) peak associated with AgNPs. The resulting PVA and PAA ultrathin layers modified and AgNPs containing PET served as bactericide and fungicide, inhibiting the growth of bacteria and fungi on the surfaces. Given PET's versatility and common use in many commercial processes, the method can be used for producing plastic surfaces with versatile antimicrobial and antibacterial properties. PMID:27196366

  16. Flexible transparent conducting composite films using a monolithically embedded AgNW electrode with robust performance stability

    NASA Astrophysics Data System (ADS)

    Im, Hyeon-Gyun; Jin, Jungho; Ko, Ji-Hoon; Lee, Jaemin; Lee, Jung-Yong; Bae, Byeong-Soo

    2013-12-01

    We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices.We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices. Electronic supplementary information (ESI) available: Further characteristics of AgNW-GFRHybrimer films and thermal oxidation of AgNW on glass. See DOI: 10.1039/c3nr05348b

  17. Probing the rupture of a Ag atomic junction in a Ag-Au mixed electrode

    NASA Astrophysics Data System (ADS)

    Kim, Taekyeong

    2015-09-01

    We probed that the atomic junction in Ag part ruptures during stretching of atomic sized contacts of Ag-Au mixed electrodes, resulting in Ag-Ag electrodes through a scanning tunneling microscope breaking junction (STM-BJ) technique. We observed that the conductance and tunneling decay constant for a series of amine-terminated oligophenyl molecular junctions are essentially the same for the Ag-Au mixed and the Ag-Ag electrodes. We also found the molecular plateau length and the evolution patterns with the Ag-Au mixed electrodes are similar to those with Ag-Ag electrodes rather than the Au-Au electrodes in the molecular junction elongation. This result is attributed to the smaller binding energy of Ag atoms compared to that of Au atoms, so the Ag junction part is more easily broken than that of Au part in stretching of Ag-Au mixed electrodes. Furthermore, we successfully observed that the rupture force of the atomic junction for the Ag-Au mixed electrodes was identical to that for the Ag-Ag electrodes and smaller than that for the Au-Au electrodes. This study may advance the understanding of the electrical and the mechanical properties in molecular devices with Ag and Au electrodes in future.

  18. 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.

  19. The AGS Booster control system

    SciTech Connect

    Frankel, R.; Auerbach, E.; Culwick, B.; Clifford, T.; Mandell, S.; Mariotti, R.; Salwen, C.; Schumburg, N.

    1988-01-01

    Although moderate in size, the Booster construction project requires a comprehensive control system. There are three operational modes: as a high intensity proton injector for the AGS, as a heavy ion accelerator and injector supporting a wide range of ions and as a polarized proton storage injector. These requirements are met using a workstation based extension of the existing AGS control system. Since the Booster is joining a complex of existing accelerators, the new system will be capable of supporting multiuser operational scenarios. A short discussion of this system is discussed in this paper.

  20. In Situ Photocatalytically Heterostructured ZnO-Ag Nanoparticle Composites as Effective Cathode-Modifying Layers for Air-Processed Polymer Solar Cells.

    PubMed

    Yuan, Kai; Chen, Lie; Chen, Yiwang

    2015-08-10

    A heterostructured semiconductor-metal ZnO-Ag nanoparticle (NP) composite was constructed through a straightforward photocatalytic strategy by using UV irradiation of ZnO NPs and an aqueous solution of Ag precursor. The ZnO-Ag NP composites serve as an effective cathode-modifying layer in polymer solar cells (PSCs) with increased short-circuit current density owing to the light-trapping effect, and improved optical and electrical conductivity properties compared with pure ZnO NPs. The Ag NPs, which are photodeposited in situ on ZnO NPs, can act as effective antennas for incident light to maximize light harvesting and minimize radiative decay or nonradiative losses, consequently resulting in the enhanced photogeneration of excitons in PSCs. Systematic photoelectron and -physical investigations confirm that heterostructured ZnO-Ag NPs can significantly improve charge separation, transport, and collection, as well as lower charge recombination at the cathode interface, leading to a 14.0 % improvement in air-processed device power conversion efficiency. In addition, this processable, cost-effective, and scalable approach is compatible with roll-to-roll manufacturing of large-scale PSCs. PMID:26135916