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Sample records for ag bi cd

  1. Fluorometric sensing of ultralow As(III) concentrations using Ag doped hollow CdS/ZnS bi-layer nanoparticles.

    PubMed

    Boxi, Siddhartha Sankar; Paria, Santanu

    2015-12-21

    Arsenic poisoning from drinking water has been an important global issue in recent years. Because of the high level toxicity of arsenic to human health, an easy, inexpensive, low level and highly selective detection technique is of great importance to take any early precautions. This study reports the synthesis of Ag doped hollow CdS/ZnS bi-layer (Ag-h-CdS/ZnS) nanoparticles for the easy fluorometric determination of As(iii) ions in the aqueous phase. The hollow bi-layer structures were synthesized by a sacrificial core method using AgBr as the sacrificial core and the core was removed by dissolution in an ammonium hydroxide solution. The synthesized nanoparticles were characterized using different instrumental techniques. A good linear relationship was obtained between fluorescence quenching intensity and As(iii) concentration in the range of 0.75-22.5 μg L(-1) at neutral pH with a limit of detection as low as 0.226 μg L(-1). PMID:26541652

  2. A rapid, partial leach and organic separation for the sensitive determination of Ag, Bi, Cd, Cu, Mo, Pb, Sb, and Zn in surface geologic materials by flame atomic absorption

    USGS Publications Warehouse

    Viets, J.G.; Clark, J.R.; Campbell, W.L.

    1984-01-01

    A solution of dilute hydrochloric acid, ascorbic acid, and potassium iodide has been found to dissolve weakly bound metals in soils, stream sediments, and oxidized rocks. Silver, Bi, Cd, Cu, Mo, Pb, Sb, and Zn are selectively extracted from this solution by a mixture of Aliquat 336 (tricaprylyl methyl ammonium chloride) and MIBK (methyl isobutyl ketone). Because potentially interfering major and minor elements do not extract, the organic separation allows interference-free determinations of Ag and Cd to the 0.05 ppm level, Mo, Cu, and Zn to 0.5 ppm, and Bi, Pb, and Sb to 1 ppm in the sample using flame atomic absorption spectroscopy. The analytical absorbance values of the organic solution used in the proposed method are generally enhanced more than threefold as compared to aqueous solutions, due to more efficient atomization and burning characteristics. The leaching and extraction procedures are extremely rapid; as many as 100 samples may be analyzed per day, yielding 800 determinations, and the technique is adaptable to field use. The proposed method was compared to total digestion methods for geochemical reference samples as well as soils and stream sediments from mineralized and unmineralized areas. The partial leach showed better anomaly contrasts than did total digestions. Because the proposed method is very rapid and is sensitive to pathfinder elements for several types of ore deposits, it should be useful for reconnaissance surveys for concealed deposits. ?? 1984.

  3. Enhanced thermoelectric performance of CdO : Ag nanocomposites.

    PubMed

    Gao, Linjie; Wang, Shufang; Liu, Ran; Zha, Xinyu; Sun, Niefeng; Wang, Shujie; Wang, Jianglong; Fu, Guangsheng

    2016-07-26

    CdO : Ag nanocomposites with metallic Ag nanoparticles embedded in the polycrystalline CdO matrix were synthesized by the solid-state reaction method. The addition of Ag led to increased grain boundaries of CdO and created numerous CdO/Ag interfaces. By incorporating Ag into the CdO matrix, the power factor was increased which was probably due to the carrier energy filtering effect induced by the enhanced energy-dependent scattering of electrons. In addition, reduced thermal conductivity was also achieved by stronger phonon scattering from grain boundaries, CdO/Ag interfaces and Ag nanoparticles. These concomitant effects resulted in enhanced ZT values for all CdO : Ag nanocomposites, demonstrating that the strategy of introducing metallic Ag nanoparticles into the CdO host was very effective in optimizing the thermoelectric performance. PMID:27411573

  4. 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.

  5. 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

  6. Facile synthesis of novel Ag/AgI/BiOI composites with highly enhanced visible light photocatalytic performances

    SciTech Connect

    Cao, Jing; Zhao, Yijie; Lin, Haili; Xu, Benyan; Chen, Shifu

    2013-10-15

    Novel Ag/AgI/BiOI composites were controllably synthesized via a facile ion-exchange followed by photoreduction strategy by using hierarchical BiOI microflower as substrate. The as-prepared Ag/AgI/BiOI composites were studied by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area analyzer and UV–vis diffuse reflectance spectroscopy (DRS). Under visible light (λ>420 nm), Ag/AgI/BiOI displayed highly enhanced photocatalytic activities for degradation of methyl orange (MO) compared to the pure hierarchical BiOI, which was mainly ascribed to the highly efficient separation of electrons and holes through the closely contacted interfaces in the Ag/AgI/BiOI ternary system. - Graphical abstract: Ag/AgI/BiOI displayed excellent photocatalytic activities for methyl orange degradation under visible light, which was mainly ascribed to the highly efficient separation of electrons and holes through Z-scheme pathway. Display Omitted - Highlights: • Novel Ag/AgI/BiOI composites were successfully synthesized. • Ag/AgI/BiOI displayed higher visible light activities than those of pure BiOI and AgI. • ·O{sub 2}{sup −} and h{sup +}, especially ·O{sub 2}{sup −}, dominated the photodegradation process of MO. • A Z-scheme pattern was adopted for Ag/AgI/BiOI activity enhancement.

  7. BiPO4 photocatalyst employing synergistic action of Ag/Ag3PO4 nanostructure and graphene nanosheets

    NASA Astrophysics Data System (ADS)

    Mohaghegh, N.; Rahimi, E.

    2016-06-01

    Graphene-supported BiPO4/Ag/Ag3PO4 photocatalyst has been fabricated by simple hydrothermal and impregnation reaction. In BiPO4/Ag/Ag3PO4 based on Reduced Graphene Oxide (RGO), this network renders numerous pathways for rapid mass transport, strong adsorption and multireflection of incident light; meanwhile, the interface between BiPO4/Ag/Ag3PO4 and RGO increases the active sites and electron transfer rate. BiPO4/Ag/Ag3PO4 based on RGO noticeably exhibited high photocatalytic activity than that of BiPO4/Ag/Ag3PO4 and P25 under visible light irradiation for cationic dye (Rhodamine B), anionic dye (methyl orange) and 4-chlorophenol (4-CP) as a neutral pollutant, which are usually difficult to be degraded over the other catalysts. This enhanced photocatalytic activity of Graphene-supported BiPO4/Ag/Ag3PO4 for all pollutants could be mainly ascribed to the reinforced charge transfer from BiPO4/Ag/Ag3PO4 to RGO, which suppresses the recombination of electron/hole pairs. Besides that, this photocatalyst can be used repetitively with a high photocatalytic activity and no apparent loss of activity occurs. The results reveal that the RGO nanosheets work as a photocatalyst promoter during the photocatalytic reaction, leading to an improved photocatalytic activity.

  8. Nanoparticle Ag-enhanced textured-powder Bi-2212/Ag wire technology

    NASA Astrophysics Data System (ADS)

    Kellams, J. N.; McIntyre, P.; Pogue, N.; Vandergrifft, J.

    2015-12-01

    A new approach to the preparation of cores for Bi-2212/Ag wire is being developed. Nanoparticle Ag is homogeneously dispersed in Bi-2212 fine powder, and the mixture is uniaxially compressed to form highly textured, cold-sintered core rods. The rods can be assembled in a silver matrix, drawn to form multifilament wire, and restacked and drawn to form multifilament wire. Preliminary studies using tablet geometry demonstrate that a nonmelt heat treatment produces densification, grain growth, intergrowth among grains, and macroscopic current transport. The status of the development is reported.

  9. Near-net-shape fabrication of continuous Ag-Clad Bi-Based superconductors

    SciTech Connect

    Lanagan, M. T. et al.

    1998-04-01

    We have developed a near-net-shape process for Ag-clad Bi-2212 superconductors as an alternative to the powder-in-tube process. This new process offers the advantages of nearly continuous processing, minimization of processing steps, reasonable ability to control the Bi-2212/Ag ratio, and early development of favorable texture of the Bi-2212 grains. Superconducting properties are discussed.

  10. Advances in fabrication of Ag-clad Bi-2223 superconductors.

    SciTech Connect

    Balachandran, U.

    1998-09-04

    Powder-in-tube (PIT) processing was used to fabricate multifilamentary Ag-clad Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) superconductors for various electric power applications. Enhancements in the transport current properties of long lengths of multifilament tapes were achieved by increasing the packing density of the precursor powder, improving the mechanical deformation, and adjusting the cooling rate. The dependence of the critical current density on magnetic field and temperature for the optimally processed tapes was measured. J{sub c} was greater than 10{sup 4} (A/cm{sup 2}) at 20 K for magnetic field up to 3 T and parallel to the c-axis which is of interest for use in refrigerator coded magnets. An attempt was made to combine the good alignment of Bi-2223 grains in Ag-sheathed superconducting tapes to obtain high J{sub c} values at high temperature and low field, and good intrinsic pinning of YBa{sub 2}Cu{sub 3}O{sub 7{minus}d} (Y-123) thin film to maintain high J{sub c} values in high fields. A new composite multifilament tape was fabricated such that the central part contained Bi-2223 filaments, with the primary function of conducting the transport current. The central Bi-2223 filaments were surrounded by Y-123 thin film to shield the applied magnetic field and protect the Bi-2223 filaments. The J{sub c} values of the composite tape were better than those of an uncoated tape. In the case of 77 K applications, an I{sub c} of about 60 A was obtained in a 150 m long tape and zero applied magnetic field. In-situ strain characteristics of the mono- and multifilament tapes were conducted.

  11. Fabrication and characterization of Ag-clad Bi-2223 tapes.

    SciTech Connect

    Balachandran, U.

    1999-04-20

    The powder-in-tube (PIT) technique was used to fabricate multifilament (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) superconducting tapes. Transport current properties of these tapes were enhanced by increasing the packing density of the precursor powder and improving the mechanical deformation condition. A critical current (I{sub c}) of > 35 A in long lengths (> 200 m) tapes has been achieved. In measuring the dependence of critical current density on magnetic field and temperature for the optimally processed tapes, we found a J{sub c} of > 10{sup 4} A/cm{sup 2} at 20 K in magnetic fields up to 3 T and parallel to the c-axis, which is of interest for use in refrigerator-cooled magnets. I{sub c} declined exponentially when an external field was applied perpendicular to the tape surface at 77 K. Mechanical stability was tested for tapes sheathed with pure Ag and Ag-Mg alloy. Tapes made with pure Ag sheathing can withstand a tensile stress of {approx}20 MPa with no detrimental effect on I{sub c} values. Mechanical performance was improved by using Ag-Mg alloy sheathing: values of transport critical current began to decrease at the tensile stress of {approx} 100 MPa. Transport current measurements on tapes wound on a mandrel of 3.81 cm (1.5 in.) diameter at 30{degree} to the longitudinal axis, showed a reduction of {approx} 10% in I{sub c} values for pure Ag-sheathed tapes and 5% reduction in I{sub c} values for Ag-Mg sheathed tapes, compared with the I{sub c} values of as-coiled tapes.

  12. Elastic Constants of the β1-AgCd Alloy

    NASA Astrophysics Data System (ADS)

    Matsuo, Yoshie; Makita, Tomoko; Suzuki, Toshiharu; Nagasawa, Akira

    1981-04-01

    The elastic constants of single crystal of β1-AgCd alloy with 47.9± 0.1 at.%Cd have been measured in a temperature range between 180 K and 360 K, using a ultrasonic pulse-cho overlapping method. It is found that with increasing temperature, the elastic constants CL{=}(C11+C12+2C44)/2 and C44 decrease linearly but C'{=}(C11-C12)/2 increases. In addition, this alloy shows a high elastic anisotropy in comparison with other Ag-based β1-phase alloys such as AgMg and AgZn.

  13. Facile synthesis of AgI/BiOI-Bi2O3 multi-heterojunctions with high visible light activity for Cr(VI) reduction.

    PubMed

    Wang, Qi; Shi, Xiaodong; Liu, Enqin; Crittenden, John C; Ma, Xiangjuan; Zhang, Yi; Cong, Yanqing

    2016-11-01

    AgI sensitized BiOI-Bi2O3 composite (AgI/BiOI-Bi2O3) with multi-heterojunctions was prepared using simple etching-deposition process. Different characterization techniques were performed to investigate the structural, optical and electrical properties of the as-prepared photocatalysts. It was found that the ternary AgI/BiOI-Bi2O3 composite exhibited: (1) improved photocurrent response, (2) smaller band gap, (3) greatly reduced charge transfer resistance and (4) negative shift of flat band potential, which finally led to easier generation and more efficient separation of photo-generated electron-hole pairs at the hetero-interfaces. Thus, for the reduction of Cr(VI), AgI/BiOI-Bi2O3 exhibited excellent photocatalytic activity under visible light irradiation at near neutral pH. AgI/BiOI-Bi2O3 was optimized when the initial molar ratio of KI to Bi2O3 and AgNO3 to Bi2O3 was 1:1 and 10%, respectively. The estimated kCr(VI) on optimized AgI/BiOI-Bi2O3 was about 16 times that on pure Bi2O3. Good stability was also observed in cyclic runs, indicating that the current multi-heterostructured photocatalyst is highly desirable for the remediation of Cr(VI)-containing wastewater. PMID:27239723

  14. Microwave-assisted solvothermal synthesis of flower-like Ag/AgBr/BiOBr microspheres and their high efficient photocatalytic degradation for p-nitrophenol

    SciTech Connect

    Li, Tingting; Luo, Shenglian; Yang, Lixia

    2013-10-15

    Flower-like Ag/AgBr/BiOBr microspheres were successfully fabricated by the approach of microwave-assisted solvothermal and in situ photo-assisted reduction. A reactive ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C{sub 16}mim]Br) was employed as Br source in the presence of surfactant polyvinylpyrrolidone (PVP). The photocatalytic activity of Ag/AgBr/BiOBr towards the decomposition of p-nitrophenol under visible light irradiation was evaluated. The results indicated that Ag/AgBr/BiOBr showed enhanced photocatalytic activity towards p-nitrophenol, comparing with P25, BiOBr and Ag/AgBr. More than 96% of p-nitrophenol was decomposed in 3.5 h under visible-light irradation. The excellent photocatalytic activity of flower-like Ag/AgBr/BiOBr microspheres can be attributed to the large specific surface area, strong visible-light absorption, suitable energy band structure and surface plasmon resonance effect of Ag nanoparticles. The possible photocatalytic mechanism was proposed based on the active species test and band gap structure analysis. - Graphical abstract: The photocatalytic reaction mechanisms of the as-prepared Ag/AgBr/BiOBr. Display Omitted - Highlights: • Successful synthesis of flower-like Ag/AgBr/BiOBr microspheres. • The Ag/AgBr/BiOBr showed much higher photocatalytic activity towards p-nitrophenol as compared to BiOBr and Ag/AgBr. • The reasons for the excellent photocatalytic activity are the large specific surface area, strong visible-light absorption and surface plasmon resonance effect of Ag nanoparticles. • The O{sub 2}·{sup −}, Br{sup 0} and photogenerated h{sup +} play key roles in the photocatalytic degradation process.

  15. RRR and thermal conductivity of Ag and Ag-0.2 wt.%Mg alloy in Ag/Bi-2212 wires

    NASA Astrophysics Data System (ADS)

    Li, P.; Ye, L.; Jiang, J.; Shen, T.

    2015-12-01

    Residual resistivity ratio (RRR) and thermal conductivity of metal matrix in metal/superconductor composite wires are important parameters for designing superconducting magnets. However, the resistivity of silver in reacted Ag/Bi-2212 wires has yet to be determined over temperature range from 4.2 K to 80 K because Bi-2212 filaments have a critical transition temperature Tc of ∼ 80 K, and because it is unknown whether the RRR of Ag/Bi-2212 degrades with Cu diffusing from Bi-2212 filaments into silver sheathes at elevated temperatures and to what degree it varies with heat treatment. We measured the resistivity of stand-alone Ag and AgMg (Ag-0.2 wt.% Mg) wires as well as the resistivity of Ag and Ag-0.2 wt.% Mg in Ag/Bi- 2212 round wires reacted in 1 bar oxygen at 890 °C for 1, 8, 24 and 48 hours and quickly cooled to room temperature. The heat treatment was designed to reduce the critical current Ic of Bi- 2212 wires to nearly zero while allowing Cu loss to fully manifest itself. We determined that pure silver exhibits a RRR of ∼ 220 while the oxide-dispersion strengthened Ag-Mg exhibits a RRR of ∼ 5 in stand-alone samples. A surprising result is that the RRR of silver in the composite round wires doesn't degrade with extended time at 890 °C for up to 48 hours. This surprising result may be explained by our observation that the Cu that diffuses into silver tends to form Cu2O precipitates in oxidizing atmosphere, instead of forming Ag-Cu solution alloy. We also measured the thermal conductivity and the magneto-resistivity of pure Ag and Ag-0.2 wt. % Mg from 4.2 K to 300 K in magnetic fields up to 14.8 T and summarized them using a Kohler plot.

  16. Solvothermal synthesis of carbon nanotube-AgBiS2 hybrids and their optical limiting properties

    NASA Astrophysics Data System (ADS)

    Liu, Dandan; Cai, Dongdong; Yang, Yan; Zhong, Huiye; Zhao, Yiwen; Song, Yinglin; Yang, Shiping; Wu, Huixia

    2016-03-01

    AgBiS2 nanoparticles (NPs) have been loaded on multiwalled carbon nanotubes (MWCNTs) by the solvothermal treatment on a mixture of MWCNTs, AgNO3, Bi(NO3)3·5H2O and thiosemicarbazide in a mixed polyol solvent. The resulting MWCNT-AgBiS2 hybrid samples have been extensively characterized by a variety of microscopic and spectroscopic techniques. The AgBiS2 NPs can be uniformly deposited on the sidewalls of MWCNTs by appropriately regulating the reaction conditions including reaction temperature and reaction time. Optical limiting (OL) studies have been performed on typical MWCNT-AgBiS2 samples using the Z-scan and OL measurements at the laser wavelength of 532 nm. The MWCNT-AgBiS2 hybrids with AgBiS2 NPs of ∼16 nm in size uniformly coated on the nanotubes show a significantly enhanced OL effect in comparison to the purified MWCNTs.

  17. Nano Ag@AgBr surface-sensitized Bi2WO6 photocatalyst: oil-in-water synthesis and enhanced photocatalytic degradation

    NASA Astrophysics Data System (ADS)

    Lin, Shuanglong; Liu, Li; Hu, Jinshan; Liang, Yinghua; Cui, Wenquan

    2015-01-01

    Nano Ag@AgBr decorated on the surface of flower-like Bi2WO6 (hereafter designated Ag@AgBr/Bi2WO6) were prepared via a facile oil-in-water self-assembly method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), etc. The characterization results indicated that nano Ag@AgBr was observed to be evenly dispersed on the surface of Bi2WO6, and was approximately 20 nm in size. Ag@AgBr/Bi2WO6 composites exhibited excellent UV-vis absorption, due to quantum dimension effect of Ag@AgBr, the surface plasmonic resonance (SPR) of Ag nanoparticles and the special flower-like structure of Bi2WO6. The photoelectrochemical measurement verified that the suitable band potential of Ag@AgBr and Bi2WO6 and the existence of metal Ag resulted in the high efficiency in charge separation of the composite. The photocatalytic activities of the Ag@AgBr/Bi2WO6 samples were examined under visible-light irradiation for the degradation of methylene blue (MB). The composite presented excellent photocatalytic activity due to the synergetic effect of Bi2WO6, AgBr, and Ag nanoparticles. The Ag@AgBr(20 wt.%)/Bi2WO6 sample exhibited the best photocatalytic activity, degrading 95.03% MB after irradiation for 2 h, which was respectively 1.29 times and 1.28 times higher than that of Ag@AgBr and Bi2WO6 photocatalyst. Meanwhile, phenol and salicylic acid were degraded to further prove the degradation ability of Ag@AgBr/Bi2WO6. Additionally, studies performed using radical scavengers indicated that O2-•, •OH and Br0 acted as the main reactive species. Based on above, a photocatalytic mechanism for organics degradation over Ag@AgBr/Bi2WO6 was proposed.

  18. Extranuclear dynamics of 111Ag(→111Cd) doped in AgI nanoparticles

    NASA Astrophysics Data System (ADS)

    Sato, W.; Mizuuchi, R.; Irioka, N.; Komatsuda, S.; Kawata, S.; Taoka, A.; Ohkubo, Y.

    2014-08-01

    Dynamic behavior of the extranuclear field relative to the 111Ag(→111Cd) probe nucleus introduced in a superionic conductor silver iodide (AgI) was investigated by means of the time-differential perturbed angular correlation technique. For poly-N-vinyl-2-pyrrolidone (PVP)-coated AgI nanoparticles, we observed nuclear spin relaxation of the probe at room temperature. This result signifies that Ag+ ions in the polymer-coated sample make hopping motion from site to site at this low temperature. The activation energy for the dynamic motion was successfully estimated to be 46(10) meV. The first atomic-level observation of the temperature-dependent dynamic behavior of Ag+ ions in the polymer-coated AgI is reported.

  19. 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.

  20. Photoluminescence and upconversion on Ag/CdTe quantum dots

    NASA Astrophysics Data System (ADS)

    Ragab, A. E.; Gadallah, A.-S.; Mohamed, M. B.; Azzouz, I. M.

    2014-11-01

    Different sizes of aqueous CdTe QDs have been prepared by microwave via controlling the temperature and time of irradiation. To study the plasmonic effect on CdTe QDs, Silver NPs were prepared by using a chemical reduction method. Structure characterization of the nanocrystals (Ag NPs and CdTe QDs) was determined by transmission electron microscopy “TEM”. For optical characterization, the absorption and photolumincence (PL) spectra were measured. It has been found that there are two opposite behaviors (quenching and enhancement) in the fluorescence spectra based on the spectral coupling strength between Ag NPs and CdTe QDs. When there is strong overlapping, PL enhancement of CdTe QDs has been observed. On the other hand, when the overlapping is weak, the PL quenching was predominant at all Ag NPS concentrations. Input-output PL intensity dependence was also studied. Upconversion photoluminescence with low excitation intensity was observed in our CdTe QDs with a standard spectrofluorometer at excitation wavelength of 800 nm. Thermally assisted surface state mechanism has been proposed to be responsible for the upconverion process.

  1. Properties of ternary Sn-Ag-Bi solder alloys. Part 2: Wettability and mechanical properties analyses

    SciTech Connect

    Vianco, P.T.; Rejent, J.A.

    1999-10-01

    Bismuth additions of 1% to 10% were made to the 96.5Sn-3.5Ag (wt.%) alloy in a study to develop a Sn-Ag-Bi ternary composition. Thermal properties and microstructural analyses of selected alloy compositions were reported in Part 1. Wettability and mechanical properties are described in this paper. Contact angle measurements demonstrated that Bi additions improved wetting/spreading performance on Cu; a minimum contact angle of 31 {+-} 4{degree} was observed with 4.83 wt.% Bi addition. Increasing the Bi content of the ternary alloy raised the Cu/solder/Cu solder joint shear strength to 81 MPa as determined by the ring-and-plug tests. TEM analysis of the 91.84Sn-3.33Ag-4.83Bi composition presented in Part 1 indicated that the strength improvement was attributed to solid-solution and precipitation strengthening effects by the Bi addition residing in the Sn-rich phase. Microhardness measurements of the Sn-Ag-Bi alloy, as a function of Bi content, reached maximum values of 30 (Knoop, 50 g) and 110 (Knoop, 5g) for Bi contents greater than approximately 4--5 wt.%.

  2. Cladding technique for development of Ag In Cd decoupler

    NASA Astrophysics Data System (ADS)

    Teshigawara, M.; Harada, M.; Saito, S.; Kikuchi, K.; Kogawa, H.; Ikeda, Y.; Kawai, M.; Kurishita, H.; Konashi, K.

    2005-08-01

    To develop a Ag (silver)-In (indium)-Cd (cadmium) alloy decoupler, a method is needed to bond the decoupler between two plates of the Al alloy (A6061-T6). We found that a better HIP condition was temperature, pressure and holding time at 803 K, 100 MPa and 1 h, respectively, for small test pieces ( ϕ 22 mm in diam. × 5 mm in height). Especially, a sandwich case (a Ag-In plate with thickness of 0.5 mm between two Ag-Cd plates with thickness of 1.25 mm) gave easier (or better) bonding results. Though a hardened layer is found in the bonding layer, the rupture strength of the bonding layer is more than 30 MPa, which is higher than the design stress in our application.

  3. Electronic spectrum of non-tetrahedral acceptors in CdTe:Cl and CdTe:Bi,Cl single crystals

    NASA Astrophysics Data System (ADS)

    Krivobok, V. S.; Nikolaev, S. N.; Bagaev, V. S.; Pruchkina, A. A.; Onishchenko, E. E.; Kolosov, S. A.; Klevkov, Yu. V.; Skorikov, M. L.

    2016-02-01

    The electronic spectra of complex acceptors in compensated CdTe:Cl, CdTe:Ag,Cl, and CdTe:Bi,Cl single crystals are studied using low-temperature photoluminescence (PL) measurements under both nonresonant and resonant excitation of distant donor-acceptor pairs (DAP). The wavelength modulation of the excitation source combined with the analysis of the differential PL signal is used to enhance narrow spectral features obscured because of inhomogeneous line broadening and/or excitation transfer for selectively excited DAPs. For the well-known tetrahedral (TD) AgCd acceptor, the energies of four excited states are measured, and the values obtained are shown to be in perfect agreement with the previous data. Moreover, splitting between the 2P3/2 (D8) and 2S3/2 (D8) states is clearly observed for AgCd centers located at a short distance (5-7 nm) from a hydrogen-like donor (ClTe). This splitting results from the reduction of the TD symmetry taking place when the acceptor is a member of a donor-acceptor pair. For the Cl-related complex acceptor with an activation energy of ˜121 meV (A-center), the energies of eight excited states are measured. It is shown that this defect produces low-symmetry central-cell correction responsible for the strong splitting of S-like TD shells. The energy spectrum of the Bi-related shallow acceptor with an activation energy of ˜36 meV is measured as well. The spectrum obtained differs drastically from the hydrogen-like set of levels, which indicates the existence of repulsive low-symmetry perturbation of the hydrogen-like Coulomb potential. It is also shown that the spectra of selectively excited PL recorded for a macroscopic ensemble of distant donor-acceptor pairs allow one to detect the low symmetry of acceptors of a given type caused by their complex nature or by the Jahn-Teller distortion. This method does not require any additional (external) field and is applicable to acceptors in diverse zinc-blende compound semiconductors.

  4. Solution-processed solar cells based on environmentally friendly AgBiS2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Bernechea, María; Miller, Nichole Cates; Xercavins, Guillem; So, David; Stavrinadis, Alexandros; Konstantatos, Gerasimos

    2016-08-01

    Solution-processed inorganic solar cells are a promising low-cost alternative to first-generation solar cells. Solution processing at low temperatures combined with the use of non-toxic and abundant elements can help minimize fabrication costs and facilitate regulatory acceptance. However, at present, there is no material that exhibits all these features while demonstrating promising efficiencies. Many of the candidates being explored contain toxic elements such as lead or cadmium (perovskites, PbS, CdTe and CdS(Se)) or scarce elements such as tellurium or indium (CdTe and CIGS(Se)/CIS). Others require high-temperature processes such as selenization or sintering, or rely on vacuum deposition techniques (Sb2S(Se)3, SnS and CZTS(Se)). Here, we present AgBiS2 nanocrystals as a non-toxic, earth-abundant material for high-performance, solution-processed solar cells fabricated under ambient conditions at low temperatures (≤100 °C). We demonstrate devices with a certified power conversion efficiency of 6.3%, with no hysteresis and a short-circuit current density of ∼22 mA cm‑2 for an active layer thickness of only ∼35 nm.

  5. First-principles study of the geometry of Ag nanowires growing on a self-assembled Bi nanoline

    NASA Astrophysics Data System (ADS)

    Koga, H.; Ohno, T.

    2007-09-01

    Epitaxial Ag nanowires on a self-assembled Bi nanoline on the Si(001) surface are examined for their geometry and energetic stability at the level of the generalized-gradient approximation. The orientations examined are Ag(001)[100], Ag(110)[100], Ag(111)[110], and Ag(001)[110], where the indices refer to the plane and the direction parallel to the Si(001) surface and the Bi nanoline, respectively. The wires are found to have mostly bulklike structure, except that Ag(001) monolayers undergo extensive reconstruction. The calculated electronic band structure indicates that the Ag wires are metallic wires. Particularly stable among the wires are the Ag(111) wires, having a coincident site lattice interface with the Bi nanoline. The energetic stability generally improves with thickness, indicating that Ag grows through three-dimensional nucleation on the Bi nanoline.

  6. RRR and thermal conductivity of Ag and Ag0.2wt%Mg alloy in Ag/Bi-2212 wires

    SciTech Connect

    Li, Pei; Ye, L.; Jiang. J., Jiang. J.; Shen, T.

    2015-08-19

    The residual resistivity ratio (RRR) and thermal conductivity of metal matrix in metal/superconductor composite wires are important parameters for designing superconducting magnets. However, the resistivity of silver in reacted Ag/Bi-2212 wires has yet to be determined over temperature range from 4.2 K to 80 K because Bi-2212 filaments have a critical transition temperature Tc of ~ 80 K, and because it is unknown whether the RRR of Ag/Bi-2212 degrades with Cu diffusing from Bi-2212 filaments into silver sheathes at elevated temperatures and to what degree it varies with heat treatment. We measured the resistivity of stand-alone Ag and AgMg (Ag-0.2wt%Mg) wires as well as the resistivity of Ag and Ag- 0.2wt%Mg in the state-of-the-art Ag/Bi-2212 round wires reacted in 1 bar oxygen at 890 °C for 1, 8, 24 and 48 hours and quickly cooled to room temperature. The heat treatment was designed to reduce the critical current Ic of Bi-2212 wires to nearly zero while allowing Cu loss to fully manifest itself. We determined that pure silver exhibits a RRR of ~ 220 while the oxide-dispersion strengthened AgMg exhibits a RRR of ~ 5 in stand-alone samples. A surprising result is that the RRR of silver in the composite round wires doesn’t degrade with extended time at 890 °C for up to 48 hours. This surprising result may be explained by our observation that the Cu that diffuses into the silver tends to form Cu2O precipitates in oxidizing atmosphere, instead of forming Ag-Cu solution alloy. We also measured the thermal conductivity and the magneto-resistivity of pure Ag and Ag-0.2 wt%Mg from 4.2 K to 300 K in magnetic fields up to 14.8 T and summarized them using a Kohler plot.

  7. The effect of high-pressure processing on unsealed Bi-2223/Ag tape

    NASA Astrophysics Data System (ADS)

    Wang, X. C.; Qu, T.-M.; Zhao, L.; Li, P.; Han, Z.

    2007-10-01

    High-pressure (HP) processing of Ag-sheathed Bi2Si2Ca2Cu3Ox (Bi-2223) tape was investigated. In Bi-2223/Ag tapes, the outer Ag sheath might act as a sealing barrier against the penetration of the high-pressure atmosphere. In this work, short tapes after final heat treatment (FHT) were not sealed hermetically with Ag foil when HP processing was applied. The results show that the average thickness of tapes after HP processing is 2.5% lower than that of FHT tapes. However, the critical current Ic for tapes is not improved by HP processing. There are still many cracks and porosity in the superconducting core and coarse superconducting filaments are sometimes observed in transverse cross section of HP processed tapes.

  8. Study on thermo-mechanical treatment in fabrication of Bi2212/Ag HTS wire

    NASA Astrophysics Data System (ADS)

    Kim, S. C.; Ha, D. W.; Oh, S. S.; Han, I. Y.; Bruzek, C. E.; Oh, J. G.; Sohn, H. S.

    2007-07-01

    Round shape Bi2212/Ag wire is isotropic, while Bi2212/Ag or Bi2223/Ag tape has anisotropic characteristics or performances with respect to magnetic field orientation, which is the only HTS wires that can be used to make Rutherford cable to transport high current. In this work, two different Bi2212/Ag round wires with different Ag ratio were fabricated using powder-in-tube method and processing factor at each step was investigated. Double stacked 385 (55 × 7) filamentary wires of various final diameter were heat treated at different melting temperatures. Microstructure after pre-annealing was investigated. Wires which have Ag ratio (silver area/superconductor area) of 0.3 and 0.42 after powder filling show similar critical current density. Higher Ag ratio wire at 0.74 mm diameter heat treated at melting temperature 890 °C shows critical current density of 2750 A/mm 2 at 4.2 K, 0 T.

  9. The interaction of Ag with Bi-Pb-Sr-Ca-Cu-O superconductor

    NASA Astrophysics Data System (ADS)

    Dou, S. X.; Song, K. H.; Liu, H. K.; Sorrell, C. C.; Apperley, M. H.; Gouch, A. J.; Savvides, N.; Hensley, D. W.

    1989-10-01

    Bi-Pb-Sr-Ca-Cu-O superconductor compounds have been doped with up to 30 wt% Ag, sintered under variable oxygen partial pressure, and characterised in terms of the electrical and crystallographic behaviour. In contrast to previous reports that claim that Ag is the only metal non-poisoning to the superconductivity of Bi-Sr-Ca-Cu-O (BSCCO), it has been found that Ag additions to Bi-Pb-Sr-Ca-Cu-O depress Tc and Jc drastically and cause a large decrease in lattice parameters when samples are treated in air or pure oxygen. However, the lattice parameters, Tc and Jc remain unaffected by Ag additions when samples are heat treated in 0.030-0.067 atm oxygen. It is clear that the Ag reacts with and destabilises the superconducting phase when the samples are treated in air or pure oxygen while, when the samples are heat treated in low oxygen partial pressures, the Ag remains as an isolated inert metal phase that improves the weak links between the grains. This discovery clearly shows the feasibility of Ag-clad superconductor wire. For Ag-clad superconductor tape of 0.1 mm 2 cross sectional area heat treated in air, Jc was measured to be 54 A/cm 2. The same specimen sintered in 0.067 atm oxygen showed that the Jc increased to 2078 A/cm 2.

  10. Phase equilibria and the thermodynamic properties of saturated solid solutions of BiTeI, Bi2TeI, and Bi4TeI1.25 compounds of the AgI-Bi-Bi2Te3-BiTeI system

    NASA Astrophysics Data System (ADS)

    Moroz, M. V.; Prokhorenko, M. V.

    2016-07-01

    The phase equilibria of the Ag-Bi-Te-I system in the part AgI-Bi-Bi2Te3-BiTeI is studied in the interval of 500-540 K by means of physicochemical analysis. Thermodynamic properties of phases are determined via EMF. Potential-forming processes occur in electrochemical cells (ECCs) of the C|Ag|glass Ag3GeS3I|D|C structure (where C denotes inert (graphite) electrodes; Ag, D denotes ECC electrodes; D denotes four-phase alloys of the AgI-Bi-Bi2Te3-BiTeI system; and Ag3GeS3I glass is the selective Ag+ conducting membrane). Linear dependences of the EMFs of cells E(T) in the interval of 505-535 K are used to calculate the values of the thermodynamic functions of BiTeI, Bi2TeI, and Bi4TeI1.25 phases saturated over silver.

  11. Fabrication, characterization and photocatalytic properties of Ag/AgI/BiOI heteronanostructures supported on rectorite via a cation-exchange method

    SciTech Connect

    Chen, Yunfang; Fang, Jianzhang; Lu, Shaoyou; Wu, Yan; Chen, Dazhi; Huang, Liyan; Xu, Weicheng; Zhu, Ximiao; Fang, Zhanqiang

    2015-04-15

    Highlights: • Ag/AgI/BiOI-rectorite was prepared by twice cation-exchange process. • Ag/AgI/BiOI-rectorite photocatalyst possessed SPR and adsorption capacity. • Ag/AgI/BiOI-rectorite exhibited highly photocatalytic activity. • Trapped holes and ·O{sub 2}{sup −} were formed active species in the photocatalytic system. - Abstract: In this work, a new plasmonic photocatalyst Ag/AgI/BiOI-rectorite was prepared via a cation exchange process. The photocatalyst had been characterized by X-ray powder diffraction (XRD), Raman spectra, nitrogen sorption (BET), field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity, which was evaluated by degradation of rhodamine B (RhB) and bisphenol A (BPA) under visible light irradiation, was enhanced significantly by loading Ag/AgI/BiOI nanoparticles onto rectorite. The photogenerated holes and superoxide radical (·O{sub 2}{sup −}) were both formed as active species for the photocatalytic reactions under visible light irradiation. The existence of metallic Ag particles, which possess the surface plasmon resonance effect, acted as an indispensable role in the photocatalytic reaction.

  12. Current-induced spin polarization in transition metals and Bi/Ag bilayers observed by spin-polarized positron beam

    NASA Astrophysics Data System (ADS)

    Zhang, Hongjun; Yamamoto, Shunya; Fukaya, Yuki; Maekawa, Masaki; Li, Hui; Kawasuso, Atsuo; Seki, Takeshi; Saitoh, Eiji; Takanashi, Koki; JAEA Team; Tohoku Team

    2015-03-01

    Current-induced spin polarization (CISP) on the outermost surfaces of Au, Cu, Pt, Pd, Ta, and W films were studied by spin-polarized positron beam (SPPB). The Au and Cu surfaces showed no significant CISP. In contrast, the Pt, Pd, Ta, and W films exhibited large CISP (3 ~ 15% per charge current of 105 A/cm2) and the CISP of Ta and W were opposite to those of Pt and Pd. The sign of the CISP obeys the same rule in spin Hall effect suggesting that the spin-orbit coupling is mainly responsible for the CISP. The outermost spin poalrization of Bi/Ag/Al2O3andAg/Bi/Al2O3 (charge currents directly connected to Ag layers) were probed by SPPB. The opposite outermost spin polarization of Bi/Ag/Al2O3andAg/Bi/Al2O3 clarified the charge-to-spin conversion in Bi/Ag bilayers. Nevertheless, the magnitudes of the outermost spin polarization of Bi(0.3 ~5)/Ag(25)/Al2O3 (numbers in parentheses denote thickness in nm) and Ag(25 ~500)/Bi(8)/Al2O3 decrease exponentially with increasing Bi thickness and Ag thickness, respectively. This provides probably the first direct evidence for spin diffusion mechanism. Financial support from JSPS Kakenhi Grant 24310072.

  13. 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

  14. 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.

  15. Synthesis and characterization of CdS/BiPO{sub 4} heterojunction photocatalyst

    SciTech Connect

    Chen, Daimei Kuang, Zheng; Zhu, Qian; Du, Yue; Zhu, Honglei

    2015-06-15

    Highlights: • A CdS/BiPO{sub 4} heterojunction was prepared by the solvothermal method. • The CdS/BiPO{sub 4} composite has the higher photocatalytic activity than the individual ones. • The optimal mass ratio of CdS to BiPO{sub 4} was 0.5. • The heterojunction structure of CdS/BiPO{sub 4} induces an effective electron–hole separation. - Abstract: A series of CdS/BiPO{sub 4} heterojunction photocatalysts with the visible-light response were synthesized by the solvothermal method. The resulting products were characterized by X-ray diffraction, Transmission electron microscopy, X-ray photoelectron spectroscopy, and UV–vis diffuse reflection spectroscopy. CdS nanoparticles with the size at range of 5–7 nm were immobilized on the surface of BiPO{sub 4} nanorods. The CdS/BiPO{sub 4} composite exhibited much higher photodegradation rate of methylene blue under visible light irradation compared to the pure CdS and BiPO{sub 4}. The optimal mass ratio of CdS to BiPO{sub 4} was 0.5, the photodegradation rate of which is 2.1 times higher than that of CdS. The enhancement of photocatalytic activity is attributed to the heterojunction structure of CdS/BiPO{sub 4} composite which induced the effective electron–hole separation between CdS and BiPO{sub 4}.

  16. High temperature phase equilibria studies in the Bi-Sr-Ca-Cu-O-Ag system

    SciTech Connect

    Margulies, Lawrence

    1999-11-08

    A variety of experimental techniques were utilized to examine the high temperature phase equilibria in the Bi-Sr-Ca-Cu-O-Ag system. Quenching studies were used to determine the liquid solubility of Ag in the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (Bi2212) melt and the details of the peritectic decomposition pathway of Bi2212 as a function on Ag content and oxygen partial pressure (PO{sub 2}). A liquid immiscibility region between oxide and Ag liquids in the 8--98 at% range was found above 900 C. Two eutectics were found in the Bi2212-Ag pseudobinary. On the oxide rich side, a eutectic exists at approximately 4 at% Ag. On the Ag rich side, a eutectic exists at approximately 98 at% Ag at a temperature of 15 C below the melting point of pure Ag. Six distinct solid phases were found to be in equilibrium with the partial melt within the Ag content and PO{sub 2} range studied. The stability of these solid phases were found to be highly sensitive to PO{sub 2}, and to a much lesser extent Ag content. High temperature x-ray diffraction (HTXRD) studies of this system are in conflict with these results. It is suggested that these discrepancies are due to experimental artifacts caused by the significant thermal gradients and lack of full bulk sampling which is inherent in conventional HTXRD designs. In part 2, a new furnace design compatible with synchrotron radiation sources is introduced to address these problems. This design allows for full bulk sampling in a low thermal gradient environment using Debye-Scherrer transmission geometry. Sample spinning is also introduced in the design to eliminate preferred orientation and incomplete powder averaging and allow for quantitative phase analysis and structural refinement. Studies on model systems are presented to demonstrate the capabilities for high resolution structural studies (Al{sub 2}O{sub 3}) and time resolved phase transformation studies (SrCO{sub 3}). Finally, the Bi2212 system is examined to confirm the quenching results

  17. Synthesis and the enhanced visible-light-driven photocatalytic activity of BiVO4 nanocrystals coupled with Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, W. Z.; Meng, Shan; Tan, Miao; Jia, L. J.; Zhou, Y. X.; Wu, Shuang; Huang, X. W.; Liang, Y. J.; Shi, H. L.

    2015-03-01

    BiVO4 nanocrystals coupled with Ag nanoparticles (Ag-BiVO4 heterogeneous nanostructures) have been prepared by a new strategy via combining a hydrothermal route with a polyol process, in which BiVO4 nanocrystals were first synthesized by a hydrothermal route, and then, Ag nanoparticles were grown on the surfaces of the presynthesized BiVO4 nanocrystals through a polyol process. The photocatalytic evaluations demonstrate that BiVO4 nanocrystals coupled with Ag nanoparticles exhibit the enhanced visible-light-driven photocatalytic activity for the degradation of methylene blue (MB) and rhodamine B (RhB). The energy alignment and diffuse reflectance property of Ag-BiVO4 heterogeneous nanostructures demonstrate that Ag nanoparticles attached on the surfaces of BiVO4 nanocrystals play double roles for the enhanced visible-light-driven photocatalytic activity. First, the Ag nanoparticles grown on the surfaces of BiVO4 nanocrystals may act as electron sinks to retard the recombination of the photogenerated electrons and holes in BiVO4 so as to improve the charge separation on its surfaces. Second, the Ag nanoparticles increase the visible light absorption of the Ag-BiVO4 photocatalyst due to surface plasmon resonance (SPR) of Ag nanoparticles. These double roles of Ag nanoparticles make Ag-BiVO4 heterogeneous nanostructures to exhibit the enhanced photocatalytic activity to decompose MB and RhB under visible light irradiation, compared to the pure BiVO4 nanocrystals. The enhanced photocatalytic activity is attributed to the charge transfer from BiVO4 to the attached Ag nanoparticles as well as SPR absorption of Ag nanoparticles. The present work not only provides an efficient route to enhance visible-light-driven photocatalytic activity of BiVO4, but also offers a new strategy for fabricating metal-semiconductor heterogeneous nanostructure photocatalysts, which are expected to show considerable potential applications in solar-driven wastewater treatment and water

  18. Improved microstructure in Ag/Bi-2223 composite tapes by systematic variation of heat treatment parameters

    NASA Astrophysics Data System (ADS)

    Tang, Y. L.; Miller, D. J.; Baurceanu, R. M.; Maroni, V. A.; Parrella, R. D.

    2002-10-01

    Multifilament-type, silver-sheathed (Bi, Pb)2Sr2Ca2Cu3Ox (Ag/Bi-2223) composite tapes produced by the powder-in-tube (PIT) method were given a first heat treatment that employed either a standard (STD) single oxygen pressure/temperature (pO2/T) set point or a novel variable pO2/T treatment referred to as thermal sliding heat treatment (TSHT). X-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy and transmission electron microscopy were employed to provide a comparative analysis of the Bi-2223 grain colony microstructure and connectivity, nonsuperconducting second phase (NSP) composition and distribution, and grain boundary character in the STD- and TSHT-type post-first-heat-treatment Ag/Bi-2223 tape specimens. The dominant NSPs in STD and TSHT specimens were (Ca, Sr)2CuO3, (Ca, Sr)14Cu24O41, and amorphous phases that were randomly distributed in the filaments. The number and size of the NSPs in the STD specimens were sufficient to cause substantial misalignment of Bi-2223 grain colonies throughout the filament cores. However, the TSHT specimens (when compared to the STD specimens) expressed an improved microstructure with fewer/smaller NSPs that were localized mainly in the interior regions of the filaments. Also, the Bi-2223 grain colonies in TSHT specimens were more robust and better aligned from the silver-sheath/Bi-2223 interface to the mid-core region of each filament.

  19. Synthesis, characterization and photocatalytic activity of new photocatalyst CdBiYO4

    NASA Astrophysics Data System (ADS)

    Du, Huiyang; Luan, Jingfei

    2012-09-01

    CdBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of CdBiYO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray spectrometry. CdBiYO4 crystallized with a tetragonal spinel structure by space group I41/amd. The lattice parameters for CdBiYO4 were a = b = 14.519 Å and c = 9.442 Å. The band gap of CdBiYO4 was estimated to be 2.41 eV. The photocatalytic degradation of methylene blue (MB) was realized under visible light irradiation with CdBiYO4 as catalyst. The results showed that CdBiYO4 owned higher photocatalytic activity compared with pure TiO2 or N-doped TiO2 for photocatalytic degradation of MB under visible light irradiation. The photocatalytic degradation of MB with CdBiYO4 or N-doped TiO2 as catalyst followed the first-order reaction kinetics, and the first-order rate constant was 0.0137 or 0.0033 min-1. After visible light irradiation for 225 min with CdBiYO4 as catalyst, complete removal and mineralization of MB were observed. The reduction of the total organic carbon, the formation of inorganic products, SO42- and NO3-, and the evolution of CO2 revealed the continuous mineralization of MB during the photocatalytic process. The possible photocatalytic degradation pathway of MB was obtained under visible light irradiation. CdBiYO4/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be utilized to resolve other environmental chemical pollution problems.

  20. Terahertz Spectroscopy of Deuterated Methylene Bi-Radical CD_2

    NASA Astrophysics Data System (ADS)

    Ozeki, Hiroyuki; Bailleux, Stephane

    2015-06-01

    Methylene, the parent of the carbene compounds, plays a crucial role in many chemical reactions. This bi-radical is a known interstellar molecule that has been detected towards hot cores in dense interstellar clouds. CH_2 is also thought to be present in cometary atmospheres. In the gas phase chemical models of both dense and diffuse molecular clouds, CH_2 is a key intermediate in interstellar carbon chemistry which is produced primarily by dissociative recombination of the methyl ion, CH^+_3. Recently tentative detection of the mono-deuterated methyl ion, CH_2D^+ has been reported toward an infrared source in the vicinity of Orion. Deuterated methylene CHD and CD_2 can be produced from this ion or its counterpart CHD^+_2 by dissociative recombination with an electron: CH2D+ + e- → CHD+ H or {CH2 + D}, CHD2+ ~+ e- → CHD+ D or CD2 + H. Thus, both CHD and CD_2 can be observed in warm interstellar clouds, where the deuterium fractionation process is important. Precise laboratory reference data are desirable for radioastronomical observation of these molecules. Here we report on our high-resolution spectroscopic investigation on the deuterated methylene radical, CD_2 (X ^3B_1) up to 1.45 THz. At present time, eleven out of the twelve fine-structure components of four pure rotational transitions have been newly recorded, and these measurements double the number of previously observed transitions. CD_2 was generated in a discharge in CD_2CO which was obtained from the flash pyrolysis of acetic anhydride-d6 ((CD_3CO)_2O). Effort is currently made to measure the astronomically important 111 - 000 transition whose fine-structure components are predicted to occur at 1.224,1.228 and 1.234 THz. D. C. Lis, P. F. Goldsmith, E. A. Bergin et al. 2009, in Submillimeter Astrophysics and Technology, ASP Conf. Ser., 417, 23. H. Ozeki and S. Saito J. Chem. Phys. 1996, 104, 2167.

  1. Spin pumping and inverse Rashba-Edelstein effect in NiFe/Ag/Bi and NiFe/Ag/Sb

    SciTech Connect

    Zhang, Wei Jungfleisch, Matthias B.; Jiang, Wanjun; Pearson, John E.; Hoffmann, Axel

    2015-05-07

    The Rashba effect is an interaction between the spin and the momentum of electrons induced by the spin-orbit coupling in surface or interface states. We measured the inverse Rashba-Edelstein effect via spin pumping in Ag/Bi and Ag/Sb interfaces. The spin current is injected from the ferromagnetic resonance of a NiFe layer towards the Rashba interfaces, where it is further converted into a charge current. Using spin pumping theory, we quantify the conversion parameter of spin to charge current to be 0.11 ± 0.02 nm for Ag/Bi and a factor of ten smaller for Ag/Sb. The relative strength of the effect is in agreement with spectroscopic measurements and first principles calculations. We also vary the interlayer materials to study the voltage output in relation to the change of the effective spin mixing conductance. The spin pumping experiment offers a straight-forward approach of using spin current as an efficient probe for detecting interface Rashba splitting.

  2. Research status of the manufacturing technology and application properties of Bi-2223/Ag tapes at Innost

    NASA Astrophysics Data System (ADS)

    Yi, H. P.; Han, Z.; Zhang, J. S.; Liu, T.; Liu, L.; Li, M. Y.; Fang, J.; Liu, Q.; Zheng, Y. K.

    2004-10-01

    The first production line of Bi-2223/Ag tapes in China has been installed in the end of 2001 with an annual production capacity of 200 km at Innova Superconductor Technology Co., Ltd. (Innost). Bi-2223/Ag tapes can be manufactured reproducibly with length up to 1 km, critical current Ic over 90 A (77 K, 0 T) and engineering critical current density Je over 9 kA/cm 2. Innost's Bi-2223/Ag tapes are being used for producing China's first HTS power cable system (30 m, 3 phase, 35 kV/25 kA), which will be put into trial operation next year. Also, Innost's products will be used for other research projects of HTS applications such as HTS motor, HTS magnet and HTS transformer in China. In order to meet the requirements of HTS applications, tremendous research efforts have been made not only in enhancing the performance and uniformity of the Bi-2223/Ag tapes, but also in improving their application properties, which include reducing AC losses and thermal conductivity, increasing insulating properties and so on. Methods for improving productivity and yield will be also introduced.

  3. Significantly Improved Mechanical Properties of Bi- Sn Solder Alloys by Ag- Doping

    NASA Astrophysics Data System (ADS)

    McCormack, M.; Chen, H. S.; Kammlott, G. W.; Jin, S.

    1997-08-01

    The addition of small amounts of Ag (less than ~;0.5 wt. %) is found to significantly improve the ductility of the binary Bi-Sn eutectic solder. The ductility improvement, more than a threefold increase in tensile elongation, is observed even at a relatively high strain rate (0.01 s-1). As the Bi-Sn binary eutectic alloy tends to fail catastrophically by brittle fracture at high strain rates, the reduced strain-rate sensitivity in the Ag-containing alloy is beneficial for improving solder reliability on sudden impacting as might be encountered during device assembly, shipping, or thermal shock/cycling. The observed increase in alloy ductility by Ag additions is attributed to a substantial refinement of the solidification microstructure.

  4. Effect of composition on critical current density of Bi2212/Ag round wires

    NASA Astrophysics Data System (ADS)

    Kim, S. C.; Ha, D. W.; Oh, S. S.; Sohn, H. S.

    2009-06-01

    We have fabricated Bi2212/Ag round wires using three kinds of precursor to study the effect of a narrow variation of composition. Slightly different compositions - Bi 2.17Sr 1.94Ca 0.89Cu 2.0O x(N13), Bi 2.15Sr 1.94Ca 0.89Cu 2.0O x(N14), and Bi 2.17Sr 1.98Ca 0.89Cu 2.0O x(N15) - were used and Sr/Ca ratio of them were 2.18, 2.18, and 2.22, respectively. The Ag ratios of the wires were 2.7-2.8 and average filament diameter was 19-21 μm. DTA analysis of the wire showed the peritectic temperature of three wires was very similar value of the range of 880-881 °C. The best engineering critical current density ( Je) of three wires at 4.2 K and 0 T was 414-448 A/mm 2 at the maximum process temperature range of 884-892 °C. The n-value of N14 showed 13.6, whereas other two wires showed lower n-value, estimating the existence of micro-cracks. Although Bi2212/Ag round wires fabricated by three kinds of composition showed similar Je value, n-value was quite different. It is likely that the fabrication process such as the drawing as well as the composition of precursor will affect on Je of Bi2212/Ag round wire.

  5. A chemically inert Rashba split interface electronic structure of C60, FeOEP and PTCDA on BiAg2/Ag(111) substrates

    NASA Astrophysics Data System (ADS)

    Cottin, Maren C.; Lobo-Checa, Jorge; Schaffert, Johannes; Bobisch, Christian A.; Möller, Rolf; Ortega, J. Enrique; Walter, Andrew L.

    2014-04-01

    The fields of organic electronics and spintronics have the potential to revolutionize the electronics industry. Finding the right materials that can retain their electrical and spin properties when combined is a technological and fundamental challenge. We carry out the study of three archetypal organic molecules in intimate contact with the BiAg2 surface alloy. We show that the BiAg2 alloy is an especially suited substrate due to its inertness as support for molecular films, exhibiting an almost complete absence of substrate-molecular interactions. This is inferred from the persistence of a completely unaltered giant spin-orbit split surface state of the BiAg2 substrate, and from the absence of significant metallic screening of charged molecular levels in the organic layer. Spin-orbit split states in BiAg2 turn out to be far more robust to organic overlayers than previously thought.

  6. Microstructure and Thermal Analysis of As-Cast Ag-Bi-Ni alloys

    NASA Astrophysics Data System (ADS)

    Fima, Przemyslaw; Garzel, Grzegorz; Berent, Katarzyna

    2016-01-01

    The calculated liquidus projection of the Ag-Bi-Ni ternary system has been experimentally examined. Alloys were prepared by induction melting, and their microstructure studied by scanning electron microscopy coupled with energy dispersive x-ray spectroscopy. Of the primary solidification phases, (Ni) solidifies over the largest concentration range, although it was found to be narrower than calculated. The range in which Bi3Ni is the primary solidification phase was found to be broader than calculated. Also, the liquid miscibility gap is broader than predicted from assessed thermodynamic parameters. Differential thermal analysis was used to study temperatures of phase transitions of as-cast alloys, and recorded temperatures of melting of Bi3Ni and BiNi phases in ternary alloys agree well with those calculated.

  7. Effect of SnO, MgO and Ag2O Mix-doping on the Formation and Superconducting Properties of Bi-2223 Ag/tapes

    NASA Astrophysics Data System (ADS)

    Lu, X. Y.; Yi, D.; Chen, H.; Nagata, A.

    The Ag/tapes with the composition Bi1.8Pb0.4Sr1.9Ca2.1Cu3.5Oy + x wt% SnO + y wt% MgO + z wt% Ag2O (x = 0, 0.2, 0.4; y = 0, 0.2; z = 0, 0.2) were prepared by sintering at 835°C for 120 h after partial-melting at 845°C for 1 h. The individual SnO doping, SnO and Ag2O mix-doping, and SnO and MgO mix-doping all decrease the conversion of Bi-2212 phase to Bi-2223 phase. The tape with individual 0.4 wt% SnO doping shows the lowest conversion and the lowest critical current density. However, the SnO, MgO and Ag2O mix-doping increase the conversion of Bi-2212 phase to Bi-2223 phase. The tape with 0.2 wt% SnO, 0.2 wt% MgO and 0.2 wt%Ag2O mix-doping shows the highest proportion of Bi-2223 phase and the highest critical current density.

  8. Enhanced photoelectrochemical and photocatalytic activity in visible-light-driven Ag/BiVO4 inverse opals

    NASA Astrophysics Data System (ADS)

    Fang, Liang; Nan, Feng; Yang, Ying; Cao, Dawei

    2016-02-01

    BiVO4 photonic crystal inverse opals (io-BiVO4) with highly dispersed Ag nanoparticles (NPs) were prepared by the nanosphere lithography method combining the pulsed current deposition method. The incorporation of the Ag NPs can significantly improve the photoelectrochemical and photocatalytic activity of BiVO4 inverse opals in the visible light region. The photocurrent density of the Ag/io-BiVO4 sample is 4.7 times higher than that of the disordered sample without the Ag NPs, while the enhancement factor of the corresponding kinetic constant in photocatalytic experiment is approximately 3. The improved photoelectrochemical and photocatalytic activity is benefited from two reasons: one is the enhanced light harvesting owing to the coupling between the slow light and localized surface plasmon resonance effect; the other is the efficient separation of charge carriers due to the Schottky barriers.

  9. Bi-2223/Ag HTS coil magnetic field properties for magnet and bias winding

    NASA Astrophysics Data System (ADS)

    Jin, J. X.; Grantham, C.; Liu, H. K.; Dou, S. X.

    1997-08-01

    Ag-clad (Bi,Pb)2Sr2Ca2Cu3O10+x high-Tc supercondicting (HTS) multifilament wire, is used to prepare a HTS coil. The magnetic field behaviour of the HTS coil is studied with respect to its critical current and magnetic field properties. The anisotropic HTS wire has strong magnetic field dependent critical current, which causes critical current degradation when used in the form of a coil. The HTS coil magnetic field is measured and its distribution is investigated. The experimental results and analysis provide basic information for the design of a magnet or bias winding with the Ag-clad (Bi,Pb)2Sr2Ca2Cu3O10+x HTS wire.

  10. Electrical and thermal characteristics of Bi2212/Ag HTS coils for conduction-cooled SMES

    NASA Astrophysics Data System (ADS)

    Hayakawa, N.; Noguchi, S.; Kurupakorn, C.; Kojima, H.; Endo, F.; Hirano, N.; Nagaya, S.; Okubo, H.

    2006-06-01

    In this paper, we investigated the electrical and thermal performance of conduction-cooled Bi2212/Ag HTS coils with 4K-GM cryocooler system. First, we measured the critical current Ic for different ambient temperatures T0 at 4.2 K - 40 K. Experimental results revealed that Ic increased with the decrease in T0 and was saturated at T0 < 10 K. We carried out thermal analysis considering heat generation, conduction and transfer under conduction-cooling condition, and reproduced the electrical and thermal characteristics of the conduction-cooled HTS coil, taking account of temperature dependence of specific heat and thermal conductivity of the materials. We also measured the temperature rise of Bi2212/Ag HTS coil for different continuous current levels at T0 = 4.8 K. Experimental results revealed the criterion of thermal runaway, which was discussed in terms of heat generation and propagation in the test coil.

  11. Fabrication of joint Bi-2223/Ag superconducting tapes with BSCCO superconducting powders by diffusion bonding

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Zou, Guisheng; Wu, Aiping; Zhou, Fangbing; Ren, Jialie

    2010-05-01

    61-Filaments Bi-2223/Ag superconducting tapes have been successfully joined with BSCCO superconducting powder interlayer by diffusion bonding. The electrical properties of the diffusion bonding joints were tested by standard four probe method and the microstructures of the joints were also examined by SEM. Additionally, the phase constituents of the superconducting powders between the tapes before and after bonding process were evaluated by XRD analysis. The result shows that the diffusion bonding joints are superconductive. The microstructures of the joint display a good bonding with no cracks and discontinuities. The joining zones are mainly composed of Bi-2223 phase, Bi-2212 phase and a small amount of CuO, Ca 2PbO 4. At last, the phase transformations of the superconducting powders in the bonding process are discussed.

  12. Syntheses and catalytic performances of Ag-Ni bi-metals

    NASA Astrophysics Data System (ADS)

    Tang, Changlin; Li, Liping; Gao, Hongbo; Li, Guangshe; Qiu, Xiaoqing; Liu, Jiang

    Ag-Ni bi-metal nanocrystals were prepared by a novel solution method, in which ethanol was first taken as a green solvent with no use of any external toxic reducing agents. The as-prepared bi-metal nanocrystals were spherical and constructed by an aggregation of tiny crystals with particle size of about 12 nm. Infrared data indicated that the surfaces of the as-prepared nanocrystals were free of organic contaminants. The obtained bi-metal nanocrystals showed great potential as the additive in promoting the decomposition of ammonium perchlorate (AP), the key component of composite solid propellants. They were also initiated as the anode material of solid oxide fuel cells (SOFCs) which showed a maximum power density of 52.34 mW cm -2 for single cell at 800 °C.

  13. Electrostatic assembles and optical properties of Au CdTe QDs and Ag/Au CdTe QDs

    NASA Astrophysics Data System (ADS)

    Yang, Dongzhi; Wang, Wenxing; Chen, Qifan; Huang, Yuping; Xu, Shukun

    2008-09-01

    Au-CdTe and Ag/Au-CdTe assembles were firstly investigated through the static interaction between positively charged cysteamine-stabilized CdTe quantum dots (QDs) and negatively charged Au or core/shell Ag/Au nano-particles (NCs). The CdTe QDs synthesized in aqueous solution were capped with cysteamine which endowed them positive charges on the surface. Both Au and Ag/Au NCs were prepared through reducing precursors with gallic acid obtained from the hydrolysis of natural plant poly-phenols and favored negative charges on the surface of NCs. The fluorescence spectra of CdTe QDs exhibited strong quenching with the increase of added Au or Ag/Au NCs. Railey resonance scattering spectra of Au or Ag/Au NCs increased firstly and decreased latter with the concentration of CdTe QDs, accompanied with the solution color changing from red to purple and colorless at last. Experimental results on the effects of gallic acid, chloroauric acid tetrahydrate and other reagents demonstrated the static interaction occurred between QDs and NCs. This finding reveals the possibilities to design and control optical process and electromagnetic coupling in hybrid structures.

  14. Multi-stage Ag-Bi-Co-Ni-U and Cu-Bi vein mineralization at Wittichen, Schwarzwald, SW Germany: geological setting, ore mineralogy, and fluid evolution

    NASA Astrophysics Data System (ADS)

    Staude, Sebastian; Werner, Wolfgang; Mordhorst, Teresa; Wemmer, Klaus; Jacob, Dorrit E.; Markl, Gregor

    2012-03-01

    The Wittichen Co-Ag-Bi-U mining area (Schwarzwald ore district, SW Germany) hosts several unconformity-related vein-type mineralizations within Variscan leucogranite and Permian to Triassic redbeds. The multistage mineralization formed at the intersection of two fault systems in the last 250 Ma. A Permo-Triassic ore stage I with minor U-Bi-quartz-fluorite mineralization is followed by a Jurassic to Cretaceous ore stage II with the main Ag and Co mineralization consisting of several generations of gangue minerals that host the sub-stages of U-Bi, Bi-Ag, Ni-As-Bi and Co-As-Bi. Important ore minerals are native elements, Co and Ni arsenides, and pitchblende; sulphides are absent. The Miocene ore stage III comprises barite with the Cu-Bi sulfosalts emplectite, wittichenite and aikinite, and the sulphides anilite and djurleite besides native Bi, chalcopyrite, sphalerite, galena and tennantite. The mineral-forming fluid system changed from low salinity (<5 wt.% NaCl) at high temperature (around 300°C) in Permian to highly saline (around 25 wt.% NaCl + CaCl2) at lower temperatures (50-150°C) in Triassic to Cretaceous times. Thermodynamic calculations and comparison with similar mineralizations worldwide show that the Mesozoic ore-forming fluid was alkaline with redox conditions above the hematite-magnetite buffer. We suggest that the precipitation mechanism for native elements, pitchblende and arsenides is a decrease in pH during fluid mixing processes. REE patterns in fluorite and the occurrence of Bi in all stages suggest a granitic source of some ore-forming elements, whereas, e.g. Ag, Co and Ni probably have been leached from the redbeds. The greater importance of Cu and isotope data indicates that the Miocene ore stage III is more influenced by fluids from the overlying redbeds and limestones than the earlier mineralization stages.

  15. 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.

  16. Loading Ag nanoparticles on Cd(II) boron imidazolate framework for photocatalysis

    NASA Astrophysics Data System (ADS)

    Liu, Min; Zhang, De-Xiang; Chen, Shumei; Wen, Tian

    2016-05-01

    An amine-functionalized Cd(II) boron imidazolate framework (BIF-77) with three-dimensional open structure has been successfully synthesized, which can load Ag nanoparticles (NPs) for photocatalytic degradation of methylene blue (MB).

  17. Bactericidal activity and mechanism of AgI/AgBr/BiOBr(0.75)I(0.25) under visible light irradiation.

    PubMed

    Liang, Jialiang; Deng, Jun; Li, Mian; Tong, Meiping

    2016-02-01

    The AgI/AgBr/BiOBr0.75I0.25 nanocomposites were synthesized by a solvothermal process, followed by an in-situ ion exchange reaction. The disinfection activities of the as-synthesized photocatalyst to model cell type, Gram-negative Escherichia coli (E. coli), were investigated under visible light irradiation condition (λ≥400 nm). Results showed that 80 mg/L AgI/AgBr/BiOBr0.75I0.25 could completely inactivate 3×10(7) CFU mL(-1)E. coli cells within 30 min under visible light irradiation. Moreover, the bactericidal mechanisms involved in the photocatalytic disinfection process were systematically investigated. Ag(+) ions released from the nanocomposites negligibly contributed to the bactericidal activity, while active species including h(+), e(-) and ·O2(-) played important roles in the disinfection system. Direct contact of bacterial cells and nanoparticles was found to be the prerequisite for both the generation of ·O2(-) and the disinfection processes. The disruption of cell membrane and emission of cytoplasm directly inactivated E. coli cells. In addition, AgI/AgBr/BiOBr0.75I0.25 exhibited strong antibacterial activity toward E. coli even in four consecutive reused cycles. PMID:26674838

  18. Bi-nanoparticle (CdTe and CdSe) mixed polyaniline hybrid thin films prepared using spin coating technique

    NASA Astrophysics Data System (ADS)

    Verma, Deepak; Dutta, V.

    2009-02-01

    Polyaniline (Pani) films containing CdTe, CdSe, and both nanoparticles were deposited using spin coating technique. Pani was chemically synthesized by oxidation method, whereas surfactant free CdTe and CdSe nanoparticles were prepared using solvothermal method. Binanoparticle films showed an increase in the absorption from 350 nm to the near IR region. Absorption spectra also showed charge transfer complex formation for the binanoparticle hybrid thin films prepared with weight ratio of [Pani (camphor sulfonic acid, CSA):CdTe:CdSe] 200:100:75. Photoluminescence measurement for the bi-nanoparticle hybrid thin films confirmed that the required dissociation of excitons was taking place at the interface. Scanning electron microscopy images showed homogeneity and an interconnected network on the surface of the films prepared with Pani (CSA):CdTe:CdSe weight ratios of 200:100:50 and 200:100:75, respectively. Cyclic voltammetry confirmed better stability for the bi-nanoparticle hybrid films in comparison to Pani film. It also established the process of electrochemical charge transfer between the nanoparticles and the polymer matrix.

  19. Correlation between microstructure and hardness of a Bi-1.5wt%Ag lead-free solder alloy

    NASA Astrophysics Data System (ADS)

    Spinelli, J. E.; Macedo, R. A.; Silva, B. L.; Garcia, A.

    2016-03-01

    In the present study a hypoeutectic Bi-1.5wt%Ag alloy was directionally solidified under transient heat flow conditions and the microstructure was analysed. Bi-Ag alloys are considered as potential alternatives to replace Pb-based alloys as solder materials for metallic connections under high temperatures. However, a lack of understanding regarding the effects of solidification thermal parameters (growth rate - VL, the cooling rate - Ṫ) on microstructural aspects is reported in literature. Another challenge is to improve properties and reliability. The results of the present study include the determination of the tip growth rate and the cooling rate by cooling curves recorded by thermocouples positioned along the casting length, metallography, X-ray fluorescence (XRF) and Vickers hardness. The entire directionally solidified Bi-1.5Ag microstructure was arranged by faceted Bi-rich dendrites surrounded by a eutectic mixture (Bi+Ag). The primary and secondary dendrite arm spacing (λ1 and λ2), the interphase spacing (λ) and the diameter of Ag-rich particles were also measured along the casting length; and experimental growth laws. Relating these microstructural features to the experimental thermal parameters are proposed.

  20. Ag/BiOBr Film in a Rotating-Disk Reactor Containing Long-Afterglow Phosphor for Round-the-Clock Photocatalysis.

    PubMed

    Yin, Haibo; Chen, Xiaofang; Hou, Rujing; Zhu, Huijuan; Li, Shiqing; Huo, Yuning; Li, Hexing

    2015-09-16

    Ag/BiOBr film coated on the glass substrate was synthesized by a solvothermal method and a subsequent photoreduction process. Such a Ag/BiOBr film was then adhered to a hollow rotating disk filled with long-afterglow phosphor inside the chamber. The Ag/BiOBr film exhibited high photocatalytic activity for organic pollutant degradation owing to the improved visible-light harvesting and the separation of photoinduced charges. The long-afterglow phosphor could absorb the excessive daylight and emit light around 488 nm, activating the Ag/BiOBr film to realize round-the-clock photocatalysis. Because the Ag nanoparticles could extend the light absorbance of the Ag/BiOBr film to wavelengths of around 500 nm via a surface plasma resonance effect, they played a key role in realizing photocatalysis induced by long-afterglow phosphor. PMID:26317239

  1. Effects of composition and cooling rate on the microstructure of Sn-3.7Ag-0.9Zn-Bi solders

    NASA Astrophysics Data System (ADS)

    Wang, X.; Liu, Y. C.; Wei, C.; Yu, L. M.; Gao, Z. M.; Dong, Z. Z.

    2009-09-01

    The effects of Bi addition, of less than 3 wt.%, and applied cooling rate on the solidified microstructure of the eutectic Sn-3.7Ag-0.9Zn (weight percent, hereafter) solder were investigated. As observed by microstructural analysis, the increase of Bi content favors the separation of the β-Sn and AgZn intermetallic compounds (IMCs) in the eutectic Sn-Ag-Zn solder. And there are some Bi precipitates formed along with the primary β-Sn dendrites as the concentration of Bi exceeds 2%. As the applied cooling rate increases, the microstructure of the Sn-3.7Ag-0.9Zn-Bi solder is refined, and the segregation of Bi is restrained. By increasing the amount of Bi, the microhardness of the solder increases.

  2. Role of internal gases and creep of Ag in controlling the critical current density of Ag-sheathed Bi2Sr2CaCu2Ox wires

    NASA Astrophysics Data System (ADS)

    Shen, T.; Ghosh, A.; Cooley, L.; Jiang, J.

    2013-06-01

    High engineering critical current density JE of > 500 A/mm2 at 20 T and 4.2 K can be regularly achieved in Ag-sheathed multifilamentary Bi2Sr2CaCu2Ox (Bi-2212) round wire when the sample length is several centimeters. However, JE(20 T) in Bi-2212 wires of several meters length, as well as longer pieces wound in coils, rarely exceeds 200 A/mm2. Moreover, long-length wires often exhibit signs of Bi-2212 leakage after melt processing that are rarely found in short, open-end samples. We studied the length dependence of JE of state-of-the-art powder-in-tube (PIT) Bi-2212 wires and gases released by them during melt processing using mass spectroscopy, confirming that JE degradation with length is due to wire swelling produced by high internal gas pressures at elevated temperatures [A. Malagoli et al. Supercond. Sci. Technol. 24, 075016 (2011) and A. Malagoli et al. Supercond. Sci. Technol. 26, 055018 (2013)]. We further modeled the gas transport in Bi-2212 wires and examined the wire expansion at critical stages of the melt processing of as-drawn PIT wires and the wires that received a degassing treatment or a cold-densification treatment before melt processing. These investigations showed that internal gas pressure in long-length wires drives creep of the Ag sheath during the heat treatment, causing wire to expand, lowering the density of Bi-2212 filaments, and therefore degrading the wire JE; the creep rupture of silver sheath naturally leads to the leakage of Bi-2212 liquid. Our work shows that proper control of such creep is the key to preventing Bi-2212 leakage and achieving high JE in long-length Bi-2212 conductors and coils.

  3. High-temperature phase equilibria studies in the Bi-Sr- Ca-Cu-O-Ag system

    NASA Astrophysics Data System (ADS)

    Margulies, Lawrence

    A variety of experimental techniques were utilized to examine the high temperature phase equilibria in the Bi- Sr-Ca-Cu-O-Ag system. Quenching studies were used to determine the liquid solubility of Ag in the Bi2Sr 2CaCu2O8 (Bi2212) melt and the details of the peritectic decomposition pathway of Bi2212 as a function on Ag content and oxygen partial pressure (PO2). A liquid immiscibility region between oxide and Ag liquids in the 8-98 at% range was found above 900°C. Two eutectics were found in the Bi2212-Ag pseudo-binary. On the oxide rich side, a eutectic exists at approximately 4 at% Ag. On the Ag rich side, a eutectic exists at approximately 98 at% Ag at a temperature of 15°C below the melting point of pure Ag. Six distinct solid phases were found to be in equilibrium with the partial melt within the Ag content and PO2 range studied. The stability of these solid phases were found to be highly sensitive to PO2, and to a much lesser extent Ag content. High temperature x-ray diffraction (HTXRD) studies of this system are in conflict with these results. It is suggested that these discrepancies are due to experimental artifacts caused by the significant thermal gradients and lack of full bulk sampling which is inherent in conventional HTXRD designs. In part II, a new furnace design compatible with synchrotron radiation sources is introduced to address these problems. This design allows for full bulk sampling in a low thermal gradient environment using Debye- Scherrer transmission geometry. Sample spinning is also introduced in the design to eliminate preferred orientation and incomplete powder averaging and allow for quantitative phase analysis and structural refinement. Studies on model systems are presented to demonstrate the capabilities for high resolution structural studies (Al 2O3) and time resolved phase transformation studies (SrCO 3). Finally, the Bi2212 system is examined to confirm the quenching results of part I, and to demonstrate the degree to which

  4. Structure of LIMP-2 provides functional insights with implications for SR-BI and CD36.

    PubMed

    Neculai, Dante; Schwake, Michael; Ravichandran, Mani; Zunke, Friederike; Collins, Richard F; Peters, Judith; Neculai, Mirela; Plumb, Jonathan; Loppnau, Peter; Pizarro, Juan Carlos; Seitova, Alma; Trimble, William S; Saftig, Paul; Grinstein, Sergio; Dhe-Paganon, Sirano

    2013-12-01

    Members of the CD36 superfamily of scavenger receptor proteins are important regulators of lipid metabolism and innate immunity. They recognize normal and modified lipoproteins, as well as pathogen-associated molecular patterns. The family consists of three members: SR-BI (which delivers cholesterol to the liver and steroidogenic organs and is a co-receptor for hepatitis C virus), LIMP-2/LGP85 (which mediates lysosomal delivery of β-glucocerebrosidase and serves as a receptor for enterovirus 71 and coxsackieviruses) and CD36 (a fatty-acid transporter and receptor for phagocytosis of effete cells and Plasmodium-infected erythrocytes). Notably, CD36 is also a receptor for modified lipoproteins and β-amyloid, and has been implicated in the pathogenesis of atherosclerosis and of Alzheimer's disease. Despite their prominent roles in health and disease, understanding the function and abnormalities of the CD36 family members has been hampered by the paucity of information about their structure. Here we determine the crystal structure of LIMP-2 and infer, by homology modelling, the structure of SR-BI and CD36. LIMP-2 shows a helical bundle where β-glucocerebrosidase binds, and where ligands are most likely to bind to SR-BI and CD36. Remarkably, the crystal structure also shows the existence of a large cavity that traverses the entire length of the molecule. Mutagenesis of SR-BI indicates that the cavity serves as a tunnel through which cholesterol(esters) are delivered from the bound lipoprotein to the outer leaflet of the plasma membrane. We provide evidence supporting a model whereby lipidic constituents of the ligands attached to the receptor surface are handed off to the membrane through the tunnel, accounting for the selective lipid transfer characteristic of SR-BI and CD36. PMID:24162852

  5. Hydrazine reduction of metal ions to porous submicro-structures of Ag, Pd, Cu, Ni, and Bi

    SciTech Connect

    Wang Yue; Shi Yongfang; Chen Yubiao; Wu Liming

    2012-07-15

    Porous submicro-structures of Ag, Pd, Cu, Ni, and Bi with high surface area have been prepared by the reduction of hydrazine in glycerol-ethanol solution at room temperature or 120-180 Degree-Sign C. Phase purity, morphology, and specific surface area have been characterized. The reactions probably undergo three different mechanisms: simple reduction for Ag and Pd, coordination-then-reduction for Cu and Ni, and hydrolysis-then-reduction for Bi. The reductant hydrazine also plays an important role to the formation of the porous submicro-structure. The reaction temperature influences the size of the constituent particles and the overall architecture of the submicro-structure so as to influence the surface area value. The as-prepared porous metals have shown the second largest surface area ever reported, which are smaller than those made by the reduction of NaBH{sub 4}, but larger than those made by hard or soft template methods. - Graphical abstract: Porous submicro-structures of Ag, Pd, Cu, Ni, and Bi with high surface area have been prepared by the reduction of hydrazine in the glycerol-ethanol solution at room temperature or 120-180 Degree-Sign C. The reactions undergo different mechanisms: simple reduction for Ag and Pd, coordination-then-reduction for Cu and Ni, and hydrolysis-then-reduction for Bi. Highlights: Black-Right-Pointing-Pointer Syntheses of porous Ag, Pd, Cu, Ni, and Bi with high surface area. Black-Right-Pointing-Pointer Ag and Pd undergo simple reduction. Black-Right-Pointing-Pointer Cu and Ni undergo coordination-then-reduction. Black-Right-Pointing-Pointer Bi undergoes hydrolysis-then-reduction. Black-Right-Pointing-Pointer The as-prepared metals have shown the second largest surface area ever reported.

  6. Benefits of Carrier-Pocket Anisotropy to Thermoelectric Performance: The Case of p -Type AgBiSe2

    DOE PAGESBeta

    Parker, David S.; May, Andrew F.; Singh, David J.

    2015-06-05

    Here we study theoretically the effects of anisotropy on the thermoelectric performance of p-type AgBiSe2. We present an apparent realization of the thermoelectric benefits of one-dimensional plate-like carrier pocket anisotropy in the valence band of this material. Based on first principles calculations we find a substantial anisotropy in the electronic structure, likely favorable for thermoelectric performance, in the valence bands of the hexagonal phase of the silver chalcogenide thermoelectric AgBiSe2, while the conduction bands are more isotropic, and in our experiments do not attain high performance. AgBiSe2 has already exhibited a ZT value of 1.5 in a high-temperature disordered fccmore » phase, but room-temperature performance has not been demonstrated. We develop a theory for the ability of anisotropy to decouple the density-of-states and conductivity effective masses, pointing out the influence of this effect in the high performance thermoelectrics Bi2Te3 and PbTe. From our first principles and Boltzmann transport calculations we find that p-type AgBiSe2 has substantial promise as a room temperature thermoelectric, and estimate its performance.« less

  7. Self-regulated route to ternary hybrid nanocrystals of Ag-Ag2S-CdS with near-infrared photoluminescence and enhanced photothermal conversion

    NASA Astrophysics Data System (ADS)

    Zhu, Guoxing; Bao, Chunlin; Liu, Yuanjun; Shen, Xiaoping; Xi, Chunyan; Xu, Zheng; Ji, Zhenyuan

    2014-09-01

    Developing hybrid nanocrystals is a hot topic in materials science. Herein, a ternary hybrid nanocrystal, Ag-Ag2S-CdS, combining near infrared emission and photothermal conversion properties was demonstrated. The ternary Ag-Ag2S-CdS hybrid nanocrystals with cubic shape and uniform size were synthesized by a simple one-pot and one-step colloidal method. The growth process is self-regulated with the formation order of Ag2S, Ag, and CdS, sequentially. The formation of Ag originates from the partial reduction of Ag2S, while the formation of CdS is through an Ag2S catalytic mechanism based on its superionic feature. The obtained ternary hybrid nanocrystals show near infrared emission and photothermal conversion properties in a lab-on-a-particle system. Importantly, an enhanced effect is observed for the photothermal conversion, which is mainly due to the presence of heterointerfaces among the crystals. This work will not only advance the synthesis chemistry of multi-component hybrid nanocrystals but also provide a possible route for the design of advanced multi-model materials used in bio-related fields.Developing hybrid nanocrystals is a hot topic in materials science. Herein, a ternary hybrid nanocrystal, Ag-Ag2S-CdS, combining near infrared emission and photothermal conversion properties was demonstrated. The ternary Ag-Ag2S-CdS hybrid nanocrystals with cubic shape and uniform size were synthesized by a simple one-pot and one-step colloidal method. The growth process is self-regulated with the formation order of Ag2S, Ag, and CdS, sequentially. The formation of Ag originates from the partial reduction of Ag2S, while the formation of CdS is through an Ag2S catalytic mechanism based on its superionic feature. The obtained ternary hybrid nanocrystals show near infrared emission and photothermal conversion properties in a lab-on-a-particle system. Importantly, an enhanced effect is observed for the photothermal conversion, which is mainly due to the presence of

  8. Dibarium tricadmium bis­muthide(-I,-III) oxide, Ba2Cd3−δBi3O

    PubMed Central

    Xia, Sheng-Qing; Bobev, Svilen

    2010-01-01

    Ba2Cd2.13Bi3O, a new bis­muthide(-I,-III) oxide, crystallizes with a novel body-centered tetra­gonal structure (Pearson code tI36). The crystal structure contains eight crystallographically unique sites in the asymmetric unit, all on special positions. Two Ba, one Cd and two Bi atoms have site symmetry 4mm, the third Bi atom has mmm. and the O atom has m2 symmetry; the second Cd site (2mm. symmetry) is not fully occupied. The layered structure is complex and can be considered as an inter­growth of two types of slabs, viz. BaCdBiO with the ZrCuSiAs type and BaCd2Bi2 with the CeMg2Si2 type. PMID:21589204

  9. Interfacial properties of the enhanced visible-light plasmonic Ag/Bi2WO6 (0 0 1) nanocomposite

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Cao, Kun; Wu, Yi; Zhang, Kun-Hao; Zhou, Ying

    2016-01-01

    First principle calculations are performed to study the interfacial photoelectric properties of Agn/Bi2WO6 (0 0 1) (n = 1, 2, 3, 4) hybrid photocatalyst. The parallel adsorption of Ag cluster leads to more energetic favorable structures due to stronger interfacial interactions. The positive charged Ag cluster may act as excited electron traps and facilitate the electron-hole separation. In particular, hybridization between Ag 5s and O 2p leads to the formation of isolated energy levels above the valence bands, and they become more dispersed with broader bandwidth with the increment of silver cluster size, which is responsible for the enhanced absorption in visible-light region. In the deep valence region, Ag 4d orbital turns more delocalized and hybrid with O 2p states as the cluster size increases, which contributes to more covalent bond feature of Ag-O. Moreover, optical spectra demonstrate obvious red-shifts of the absorption edge with the increment of silver content, which enhances efficiently the visible-light photocatalytic activities of Bi2WO6 (0 0 1). The study provides insights into the enhanced photocatalyic mechanism of Ag/Bi2WO6 (0 0 1) and aids in the design of noble metal loaded visible-light plasmonic photocatalyst.

  10. Preparation of Ag/AgCl/BiMg{sub 2}VO{sub 6} composite and its visible-light photocatalytic activity

    SciTech Connect

    Guo, Rui; Zhang, Gaoke; Liu, Jiu

    2013-05-15

    Graphical abstract: - Abstract: A novel composite photocatalyst Ag/AgCl/BiMg{sub 2}VO{sub 6} was synthesized by depositing Ag/AgCl nanoparticles on BiMg{sub 2}VO{sub 6} substrate via a precipitation–photoreduction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDXA), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectrophotometer (UV–vis DRS). The photocatalyst showed high and stable photocatalytic activity for photocatalytic degradation of acid red G under visible-light irradiation (λ > 420 nm). In addition, the active ·O{sub 2}{sup −} and h{sup +}, as main reactive species, played the major roles during the reaction process. The high photocatalytic activity of the composite may be related to the efficient electron–hole pairs separation at the photocatalyst interfaces, as well as the surface plasmon resonance of Ag nanoparticles formed on AgCl particles in the degradation reaction.

  11. Effect on properties of 42Sn58Bi solder joint by adding the 96.5Sn3.5Ag

    NASA Astrophysics Data System (ADS)

    Tang, Qinghua; Pan, Xiaoguang; Wu, C. M. L.; Chan, Y. C.

    2000-05-01

    The different composition in 42Sn58Bi and 96.5Sn3.5Ag system has been studied. The reflow conditions of various composition pastes were studied, and a suitable adding of Sn-Ag paste could raise the soldering temperature of paste. It was found that the shear tensile strength of solder joint could be improved after adding suitable Sn-Ag to Sn-Bi paste by testing the solder joint tension. The thermal fatigue properties were studied through performed thermal annealing and thermal shocking. The shear tensile strength of solder joints for adding suitable Sn-Ag is higher than the pure Sn- Bi after thermal shocking. The solder property, mechanical and fatigue failure properties of solder joint for adding suitable Sn-Ag could be improved. It was found that suitable Sn-Ag could decrease the porosity in Sn-Bi solder joint thought X-ray and SEM analysis.

  12. Ag adsorption on Cd-terminated CdS (0 0 0 1) and S-terminated CdS (0 0 0 1-bar) surfaces: First-principles investigations

    SciTech Connect

    Ma, Yandong; Dai, Ying; Wei, Wei; Liu, Xianghong; Huang, Baibiao

    2011-04-15

    First-principles calculations are performed to study the adsorption of Ag at Cd-terminated CdS (0 0 0 1) and S-terminated CdS (0 0 0 1-bar) surfaces as a function of Ag coverage. Our results reveal that Ag adsorption at Cd-terminated (0 0 0 1) has a large binging energy than at S-terminated (0 0 0 1-bar) surface. For Ag adsorption at Cd-terminated (0 0 0 1) surface, T4 structure is more favorable and the Ag-Cd bond posses an ionic-like character. While for Ag adsorption at S-terminated (0 0 0 1-bar) surface, the H3 structure is most stable and the bonding between Ag-S is covalent. It is found that the magnitude and the sign of surface dipole moment are partly determined by the difference between the electronegativities of Ag and the host atom bonding with Ag. The adsorption energy changes as a function of Ag coverage. In addition, related properties of Ag cluster adsorption at Cd-terminated (0 0 0 1) surface are also discussed. -- Graphical abstract: We studied the adsorption of Ag at Cd-terminated CdS (0 0 0 1) and S-terminated CdS (0 0 0 1-bar) surfaces as a function of Ag coverage by means of the first-principles calculations. In addition, related properties of Ag cluster adsorption at Cd-terminated (0 0 0 1) surface are also discussed. Our ab initio calculations are useful complement to the intense experimental studies for Ag-CdS interface. Display Omitted Research highlights: {yields} Ag adsorption effects on electronic structure and associated physics properties of CdS is systemically studied. {yields} The surface dipole moment is partly determined by the difference between the electronegativities of silver and the host atom bonding with silver. {yields} The characteristic of Ag cluster (Ag{sub 2}, Ag{sub 4}, and Ag{sub 7}) adsorption on the CdS (0 0 0 1) surface is discussed.

  13. Investigation of the origin of deep levels in CdTe doped with Bi

    SciTech Connect

    Saucedo, E.; Franc, J.; Elhadidy, H.; Horodysky, P.; Ruiz, C. M.; Bermudez, V.; Sochinskii, N. V.

    2008-05-01

    Combining optical (low temperature photoluminescence), electrical (thermoelectric effect spectroscopy), and structural (synchrotron X-ray powder diffraction) methods, the defect structure of CdTe doped with Bi was studied in crystals with dopant concentration in the range of 10{sup 17}-10{sup 19} at./cm{sup 3}. The semi-insulating state observed in crystals with low Bi concentration is assigned to the formation of a shallow donor level and a deep donor recombination center. Studying the evolution of lattice parameter with temperature, we postulate that the deep center is formed by a Te-Te dimer and their formation is explained by a tetrahedral to octahedral distortion, due to the introduction of Bi in the CdTe lattice. We also shows that this model agrees with the electrical, optical, and transport charge properties of the samples.

  14. Studies of Porosity, Connectivity, and Parasitic Phases in Textured Bi-2212/Ag after Non-Melt Sintering.

    NASA Astrophysics Data System (ADS)

    Lu, Feng; Damborsky, Kyle; McIntyre, Peter; McInturff, Al; Pogue, Nathaniel; Smit, Klaus

    2011-10-01

    High-angle grain boundaries (HAGBs) result in weak links that limit current transport in high temperature superconductors. The powder filling in commercially available Bi-2212 round wires has random orientation of the grains, and as a result HAGBs are formed during the partial-melt processing. We have developed an alternative method in which Bi-2212 fine powder is roll-processed to produce a continuous ribbon with a high degree of texture. In this study textured Bi-2212 pellets were subjected to sintering to investigate the impact of sintering on texture, density, connectivity, and microstructure. A regime of non-melt sintering parameters were identified which produce near-solid density, improved texture, extensive growth of the Bi-2212 phase, and no significant growth of parasitic phases. We are now applying the process to develop continuous ribbons of textured Bi-2212/Ag green wire in our ``Textured Powder Jelly-Roll'' process.

  15. Pb-Bi-Ag-Cu-(Hg) chemistry of galena and some associated sulfosalts. A review and some new data from Colorado California and Pennsylvania

    USGS Publications Warehouse

    Foord, Eugene E.; Shawe, Daniel R.

    1989-01-01

    Galena, associated with Pb-Bi-Ag sulfosalts and simple sulfides, contains varied amounts of Ag and Bi in the Dandy vein system, Idarado mine, Ouray, Colorado; the Jackass mine, Darwin District, California; and the Leadville district, Colorado. Silver- and bismuth-bearing galena associated with minor amounts of pyrite, chalcopyrite and sphalerite occur at the Pequea mine, Lancaster County, Pennsylvania. Ag and Bi contents in the Dandy suite of galena range from about 1.4 to 3.4 and 2.5 to 6.5 wt.% respectively, and are comparable or lower in galena from the other localities. Exsolved matildite is present in galena from the Dandy, Jackass and Leadville localities. The presence in significant amounts of both Ag and Bi in a Pb-rich sulfide system is necessary for formation of PbSss (galena solid-solution). If Ag (especially) and Bi (to a lesser extent) are absent, the galena formed will be essentially pure PbS. Some minor Sb may substitute for Bi. Compositional data for all of the galena samples are in agreement with a previously proposed linear relationship between a and Ag-Bi(Sb) content. Matildite and seven additional Pb-Bi-Ag-Cu sulfosalts have been identified from the Dandy vein system, based on electron-microprobe analyses and some X-ray powder-diffraction data.

  16. Facile Fabrication of Bi2WO6/Ag2S Heterostructure with Enhanced Visible-Light-Driven Photocatalytic Performances.

    PubMed

    Tang, Rongfeng; Su, Huaifen; Sun, Yuanwei; Zhang, Xianxi; Li, Lei; Liu, Caihua; Wang, Bingquan; Zeng, Suyuan; Sun, Dezhi

    2016-12-01

    In this report, a novel photocatalyst based on Bi2WO6/Ag2S heterostructures was prepared by a 3-mercaptopropionic acid (MPA)-assisted route at room temperature. Compared to bare Bi2WO6 and Ag2S nanoparticles, the as-formed Bi2WO6/Ag2S heterostructures exhibit enhanced photocatalytic activity for the degradation of rhodamine B (Rh B) under visible-light irradiation. This kind of enhancement in the photocatalytic activity is considered to be the synergistic effects of both the effective electron-hole separation and expansion of the light-absorption range. The pH of the solution is of vital importance to the photocatalytic activity of the as-formed Bi2WO6/Ag2S heterostructures. Under low pH value, the photosensitization process is suppressed, while under higher pH value, the photosensitization process is favored. The mechanism of the photocatalytic process was proposed by the active-species-trapping experiments, indicating that the photogenerated holes (h(+)) play a crucial role in the degradation of Rh B under visible light. The enhanced photocatalytic performance of this heterostructure makes it a promising material for the treatment of dye-containing wastewater. PMID:26951126

  17. Enhanced visible light photocatalytic performance of ZnO nanowires integrated with CdS and Ag2S.

    PubMed

    Chen, Chienhua; Li, Zhengcao; Lin, Hehnan; Wang, Guojing; Liao, Jiecui; Li, Mingyang; Lv, Shasha; Li, Wei

    2016-02-18

    A series of ZnO-CdS-Ag2S ternary nanostructures with different amounts of Ag2S were prepared using simple and low-cost successive ionic layer adsorption and reaction (SILAR) and a chemical precipitation method. The ZnO nanowires, with a diameter of ∼100 nm and a length of ∼1 μm, were modified by coating CdS and Ag2S. CdS has a high absorption coefficient and can efficiently match with the energy levels of ZnO, which can enhance the light absorption ability of the nanostructures. In addition, Ag2S with a narrow band gap was used as the main light absorber and played an important role in increasing the light absorption in the visible light region. The photocatalytic activity of the ZnO-CdS-Ag2S ternary nanostructures was investigated using the degradation of methyl orange (MO) in an aqueous solution under visible light. The ZnO-CdS-Ag2S ternary nanostructures were found to be more efficient than ZnO nanowires, ZnO-CdS nanowires, and ZnO-Ag2S nanowires. There is 7.68 times more photocatalytic activity for MO degradation in terms of the rate constant for ZnO-CdS-Ag2S 15-cycle ternary nanostructure compared to the as-grown ZnO. Furthermore, the effect of the amount of Ag2S and CdS on the ZnO surface on the photocatalytic activity was analyzed. The superior photo-absorption properties and photocatalytic performance of the ZnO-CdS-Ag2S ternary nanostructures can be ascribed to the heterostructure, which enhanced the separation of the photo-induced electron-hole pairs. In addition, visible light could be absorbed by ZnO-CdS-Ag2S ternary nanostructures rather than by ZnO. PMID:26815888

  18. EFG Studies at 111Cd in InBi Systems

    NASA Astrophysics Data System (ADS)

    Pal, G.; Sebastian, K. C.; Somayajulu, D. R. S.

    2001-11-01

    TDPAC study of InBi1-x Te x with x=0.0, 0.01, 0.05, 0.1 and 0.2 as a function of temperature is done. Both pure and Te-doped samples show a semi-metallic character up to around room temperature. Above room temperature a steep transition to semiconducting state was observed, which is independent of the doping concentrations. Hence Te may be in the interstitial sites. Conductivity measurement of the above samples showed the same trend as observed in the EFG studies. Thus the importance of the conduction electron density is prominently seen in these systems.

  19. Conduction and magnetization improvement of BiFeO{sub 3} multiferroic nanoparticles by Ag{sup +} doping

    SciTech Connect

    Ahmed, M.A.; Mansour, S.F.; El-Dek, S.I.; Abu-Abdeen, M.

    2014-01-01

    Graphical abstract: HRTEM micrographs of the samples BiFeO{sub 3}. - Highlights: • Flash auto combustion method was successful in the preparation of Ag doped BiFeO{sub 3} in nanosize. • Ag doping results in hexagonal platelet shapes up to x = 0.10, at x ≥ 0.15 needle shape predominates. • Mixed conduction is obtained in Ag doped samples. • This nanometric multiferroic could be recommended as attractive cathode for solid oxide fuel cell. - Abstract: Nanometric multiferroic namely Ag doped (BiFeO{sub 3}) was synthesized using flash auto combustion technique and glycine as a fuel. Single phase rhombohedral–hexagonal perovskite structure was obtained by annealing at 550 °C, as determined from XRD. High resolution transmission electron microscope (HRTEM) clarifies the hexagonal platelet shape with size 17.9 nm. Maximum room temperature AC conductivity was obtained at Ag content of x = 0.10. The results of this study promote the use of such multiferroic in solid oxide fuel cell applications.

  20. Thermal-mechanical properties of epoxy-impregnated Bi-2212/Ag composite

    DOE PAGESBeta

    Li, Pei; Wang, Yang; Fermi National Accelerator Lab.; Godeke, Arno; National High Magnetic Field Lab., Tallahassee, FL; Ye, Liyang; Fermi National Accelerator Lab.; Flanagan, Gene; Shen, Tengming

    2014-11-26

    In this study, knowledge of the thermal-mechanical properties of epoxy/superconductor/insulation composite is important for designing, fabricating, and operating epoxy impregnated high field superconducting magnets near their ultimate potentials. We report measurements of the modulus of elasticity, Poisson's ratio, and the coefficient of thermal contraction of epoxy-impregnated composite made from the state-of-the-art powder-in-tube multifilamentary Ag/Bi2Sr2CaCu2Ox round wire at room temperature and cryogenic temperatures. Stress-strain curves of samples made from single-strand and Rutherford cables were tested under both monotonic and cyclic compressive loads, with single strands insulated using a thin TiO2 insulation coating and the Rutherford cable insulated with a braided ceramicmore » sleeve.« less

  1. Effect of bending and tension on the voltage-current relation of Bi-2223/Ag

    NASA Astrophysics Data System (ADS)

    Ahoranta, Maria; Lehtonen, Jorma; Kováč, Pavol; Hušek, Imrich; Melišek, Tibor

    2004-01-01

    The critical current in a strained HTS tape degrades due to filament cracking. Here, the voltage-current characteristics of bent and tensioned Bi-2223/Ag tapes have been measured. In the case of tension the voltage characteristics were also measured over different sections of the sample to obtain local curves. Because the crack formation is stochastic the influence of stress on the distribution of the critical current along the tape length is studied with statistical methods. Attention is paid on the effect of different stress distribution caused by bending and tension. Because the local properties cannot be uniquely determined from the measured voltage-current characteristics the limits of applicability for these models are discussed. In the analysis emphasis is put on the dynamic n-value.

  2. AC loss in stacks of Bi-2223/Ag tapes modified with ferromagnetic covers at the edges

    NASA Astrophysics Data System (ADS)

    Safran, S.; Gömöry, F.; Gencer, Ali

    2010-10-01

    We investigated the magnetization loss of stacked Bi-2223/Ag tapes with a ferromagnetic cover on the edges. Such modification has been found recently to reduce the AC loss of a single tape; however, the behavior in a coil winding could be different. With experiments and numerical calculations we show that a ferromagnetic cover on the edges of a superconducting tape could reduce its magnetization loss also when the tapes are arranged in a stack. The effect is weaker for larger numbers of tapes but nevertheless remained significant in a stack of four tapes, which was the maximum number studied here. The effects observed experimentally are nicely explained by the results of numerical calculations.

  3. Thermal-mechanical properties of epoxy-impregnated Bi-2212/Ag composite

    SciTech Connect

    Li, Pei; Wang, Yang; Godeke, Arno; Ye, Liyang; Flanagan, Gene; Shen, Tengming

    2014-11-26

    In this study, knowledge of the thermal-mechanical properties of epoxy/superconductor/insulation composite is important for designing, fabricating, and operating epoxy impregnated high field superconducting magnets near their ultimate potentials. We report measurements of the modulus of elasticity, Poisson's ratio, and the coefficient of thermal contraction of epoxy-impregnated composite made from the state-of-the-art powder-in-tube multifilamentary Ag/Bi2Sr2CaCu2Ox round wire at room temperature and cryogenic temperatures. Stress-strain curves of samples made from single-strand and Rutherford cables were tested under both monotonic and cyclic compressive loads, with single strands insulated using a thin TiO2 insulation coating and the Rutherford cable insulated with a braided ceramic sleeve.

  4. Thermal-mechanical Properties of Epoxy-impregnated Bi-2212/Ag Composite

    SciTech Connect

    Li, Pei; Wang, Yang; Godeke, Arno; Ye, Liyang; Flanagan, Gene; Shen, Tengming

    2014-11-26

    Knowledge of the thermal-mechanical properties of epoxy/superconductor/insulation composite is important for designing, fabricating, and operating epoxy impregnated high field superconducting magnets near their ultimate potentials. We report measurements of the modulus of elasticity, Poisson’s ratio, and the coefficient of thermal contraction of epoxy-impregnated composite made from the state-of-the-art powder-in-tube multifilamentary Ag/Bi2Sr2CaCu2Ox round wire at room temperature and cryogenic temperatures. Stress-strain curves of samples made from single-strand and Rutherford cables were tested under both monotonic and cyclic compressive loads, with single strands insulated using a thin TiO2 insulation coating and the Rutherford cable insulated with a braided ceramic sleeve.

  5. Understanding Processing, Microstructure and Transport Relationships of Bi2Sr2CaCu2Ox/Ag Round Wires

    NASA Astrophysics Data System (ADS)

    Naderi, Golsa

    Superconducting magnets generating magnetic fields above 25 T are needed for many scientific applications. Due to fundamental limitations to NbTi and Nb3Sn, such high-field superconducting magnets require alternative high-field conductors. One candidate conductor is round wire composites of Bi2Sr2CaCu2Ox sheathed in an Ag-alloy matrix (Bi2212/Ag). The performance of such wires is sensitive to the heat treatment, so improvements in the critical current density (Jc) require a thorough understanding of the processing-structureproperties relationships. Due to the complex microstructure-transport relationships, their performance is far from optimized, and the potential for further increase in Jc remains. In this research a new heat treatment approach, saw-tooth processing (STP) is introduced based upon previous results showing that Bi2212 nucleation is site-saturation limited. STP increases Jc by 120% and 70% relative to partial-melt processing at 5 T and self-field respectively. The effects of STP heat treatment parameters on the microstructure and transport properties are discussed. It is shown that wires with the highest transport critical current densities primarily have filaments with two types of microstructures, one comprised primarily highly textured Bi2212 grains, and another with a noticeable amount of Bi2Sr2CuOX with the Bi2212. After processing, multifilamentary Bi2212 round wires have complex microstructures. In melt processed Bi2212/Ag wires the primary impurity is Bi2Sr 2CuOx (Bi2201), which forms as mesoscopic grains and nanoscopic intergrowths. Microstructureproperties relationship studies are performed based on the hypothesis that Bi2201 plays critical roles in transport depending on the micron-size length scale. Mesoscopic microstructures are analyzed quantitatively using a statistical approach in which filaments are categorized based on the predominant phases observed by scanning electron microscope (SEM). A Matlab program is created to analyze the

  6. Martensitic transformation behavior in Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys

    SciTech Connect

    Jang, Jai-young; Chun, Su-jin; Kim, Nam-suk; Cho, Jeung-won; Kim, Jae-hyun; Yeom, Jong-taek; Kim, Jae-il; Nam, Tae-hyun

    2013-12-15

    Graphical abstract: - Highlights: • Ag, In and Sn were soluble in TiNi matrix, while Sb, Te, Tl, Pb and Bi were not. • The B2-R-B19′transformation occurred in Ti-Ni-(Ag, In, Sn) alloys. • Solid solution hardening was essential for inducing the B2-R transformation. - Abstract: The microstructures and transformation behaviors of Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys were investigated using electron probe micro-analysis (EPMA), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Micro Vickers hardness tests. All specimens consisted of Ti–Ni matrices and second phase particles. Ag, In and Sn were soluble in Ti–Ni matrices with a limited solubility (≤1.0 at%), while Sb, Te, Tl, Pb and Bi were not soluble. Two-stage B2-R-B19′ transformation occurred in Ti–48.8Ni–1.2Ag, Ti–49.0Ni–1.0In and Ti–49.0Ni–1.0Sn alloys, while one-stage B2-B19′ transformation occurred in Ti–49.0Ni–1.0Ag, Ti–49.0Ni–1.0Sb, Ti–49.0Ni–1.0Te, Ti–49.0Ni–1.0Pb and Ti–49.0Ni–1.0Bi alloys. Micro Vickers hardness of the alloys displaying the B2-R-B19′ transformation (Hv 250–368) was much larger than that (

  7. Irreversibility behavior in Ag-sheathed Bi-based superconducting wires

    SciTech Connect

    Dou, S.X.; Liu, H.K.; Guo, Y.C.; Wang, J.; Jin, X.J.; Hu, Q.Y.; Shi, D.L.; Salem-Sugui, S.; Wang, Z.

    1992-04-01

    Irreversibility lines for Ag/(Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y}(2223) wires prepared through a phase formation- decomposition-recovery (PFDR) process and normal annealing process were determined using both AC susceptibility measurements under DC fields and magnetisation measurements. It was found that flux pinning was enhanced in the PFDR processed samples over the normal processed samples, in particular at temperature above 77 K. The PFDR process results in high mass density, grain alignment, uniform distribution of impurity precipitates and high density of defects. The irreversibility temperatures scaled with the applied field according to H{sup 1/3}, which is in contrast to H{sup 2/3} law for YBa{sub 2}Cu{sub 3}O{sub 7-x} and conventional superconductors. The irreversibility lines for PFDR processed tapes showed a crossover with those for normal processed tapes at temperature below {Tc} of the (Bi,Pb){sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} (2212), suggesting that at temperature above {Tc} of the 2212 phase, the 2212 as nonsuperconducting region, may serve as effective pinning sites for fluxoids.

  8. Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method.

    PubMed

    Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

    2015-12-01

    Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor-Ag2S (0.9 eV) quantum dots (QDs)-in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields. PMID:26428017

  9. CD226 as a genetic adjuvant to enhance immune efficacy induced by Ag85A DNA vaccination.

    PubMed

    Li, Yan; Yang, Fangli; Zhu, Junfeng; Sang, Lixuan; Han, Xue; Wang, Danan; Shan, Fengping; Li, Shengjun; Sun, Xun; Lu, Changlong

    2015-03-01

    Antigen-85A (Ag85A) is one of the major proteins secreted by Mycobacterium tuberculosis. Many studies on animal models have shown that vaccination with the recombinant Ag85A-DNA or Ag85A protein induces powerful immune response. However, these vaccines cannot generate sufficient protective immunity in the systemic compartment. CD226, a member of the immunoglobulin superfamily, is expressed in the majority of NK cells, T cells, monocytes, and platelets, and can be served as a co-stimulator that contributes to multiple innate and adaptive responses. However, there has been no study where either CD226 protein or DNA has been used as an adjuvant for vaccine development. The aim of this study was to develop a novel Ag85A DNA vaccine with CD226 as the genetic adjuvant to increase the immune efficacy induced by Ag85A. Oral vaccination with pcDNA3.1-Ag85A-CD226 DNA induced potent immune responses in mice. CD226 was an effective genetic adjuvant that improved the immune efficacy induced by Ag85A and enhanced the activity of cytotoxic T lymphocytes (CTL) and NK cells in mice. Th1 dominant cytokines (i.e. IL-2, IFN-γ and TNF-α), cellular immunity (i.e. CD4(+)IFN-γ(+)T cells and CD8(+)IFN-γ(+)T cells in splenocytes) and MLNs were also significantly elevated by pcDNA3.1-Ag85A-CD226 DNA vaccination. Our results suggest that CD226 is an effective adjuvant to enhance the immune efficacy induced by Ag85A. Our findings provide a new strategy for the development of a DNA vaccine co-expressing Ag85A and CD226. PMID:25582686

  10. Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method

    NASA Astrophysics Data System (ADS)

    Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

    2015-10-01

    Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor—Ag2S (0.9 eV) quantum dots (QDs)—in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs fabricated by uniformly depositing the QDs into the TNTs via the successive ionic layer adsorption and reaction (SILAR) method were synthesized, respectively. The X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectrum (XPS) results demonstrated that the Ag2S/CdS/TNTs prepared by SSM and other films were successfully prepared. In comparison with the four films of TNTs, CdS/TNTs, Ag2S/TNTs, and Ag2S/CdS/TNTs by SILAR, the Ag2S/CdS/TNTs prepared by SSM showed much better absorption capability and the highest photocurrent density in UV-vis range (320~800 nm). The cycles of local deposition have great influence on their photoelectric properties. The photocurrent density of Ag2S/CdS/TNTs by SSM with optimum deposition cycles of 6 was about 37 times that of TNTs without modification, demonstrating their great prospective applications in solar energy utilization fields.

  11. One-pot synthesis of Ag+ doped BiVO4 microspheres with enhanced photocatalytic activity via a facile hydrothermal method

    NASA Astrophysics Data System (ADS)

    Zhu, Shiwen; Li, Quanguo; Li, Feng; Cao, Wei; Li, Taohai

    2016-05-01

    The Ag+/BiVO4 photocatalyst was fabricated through a facile hydrothermal method by using K6V10O28·9H2O as the vanadium source. The impact of Ag+ on the product's structure and morphology was studied. It was shown that the amount of Ag+ has no effect on the product's crystal phases but plays an important role on the morphology of the nanoparticles that construct the shell of BiVO4 microspheres. In addition, the Ag+-doped photocatalysts have much higher photocatalytic activities in removing RhB and MB under the UV light illumination than the pure BiVO4. A possible photocatalytic mechanism was proposed in photoexcitation of the BiVO4 electrons which subsequently captured by the dopant. The present work may offer a novel route to reach higher photocatalytic activity by doping the Ag+ in the semiconductor catalysts.

  12. Bi2Sr2CaCu2O8 + x round wires with Ag/Al oxide dispersion strengthened sheaths: microstructure-properties relationships, enhanced mechanical behavior and reduced Cu depletion

    NASA Astrophysics Data System (ADS)

    Kajbafvala, Amir; Nachtrab, William; Wong, Terence; Schwartz, Justin

    2014-09-01

    Ag/Al alloys with various Al content (0.50 wt%, 0.75 wt%, 1.00 wt%, and 1.25 wt%) are made by powder metallurgy and used as the outer sheath material for Bi2Sr2CaCu2O8 + x (Bi2212)/Ag/AgAl multifilamentary round wires (RW). Bi2212/Ag/AgAl RW microstructural, mechanical and electrical properties are studied in various conditions, including as-drawn, after internal oxidation, and after partial melt processing (PMP). The results are compared with the behavior of a Bi2212/Ag/Ag0.20Mg wire of the same geometry. The grains in as-drawn Ag/Al alloys are found to be ˜25% smaller than those in the corresponding Ag/0.20 wt%Mg, but after PMP, the Ag/Al and Ag/0.20 wt%Mg grain sizes are comparable. Tensile tests show that Bi2212/Ag/AgAl green wires have yield strength (YS) of ˜115 MPa, nearly 65% higher than that of Bi2212/Ag/Ag0.20Mg. After PMP, the Bi2212/Ag/AgAl YS is about 35% greater than that of Bi2212/Ag/Ag0.20Mg. Furthermore, Bi2212/Ag/AgAl wires exhibit higher ultimate tensile strength and modulus and twice the elongation-to-failure. Atomic resolution high-angle annular dark-field scanning transmission electron microscopy, high resolution transmission electron microscopy and energy dispersive spectroscopy demonstrate the formation of nanosize MgO and Al2O3 precipitates via internal oxidation. Large spherical MgO precipitates are observed on the Ag grain boundaries of Ag/0.20 wt%Mg alloy, whereas the Al2O3 precipitates are distributed homogenously in the dispersion-strengthened (DS) Ag/Al alloy. Furthermore, it is found that less Cu diffused from the Bi2212 filaments in the Bi2212/Ag/Ag0.75Al wire during PMP than from the filaments in the Bi2212/Ag/Ag0.20Mg wire. These results show that DS Ag/Al alloy is a strong candidate for improved Bi2212 wire.

  13. Development of aluminum (Al5083)-clad ternary Ag In Cd alloy for JSNS decoupled moderator

    NASA Astrophysics Data System (ADS)

    Teshigawara, M.; Harada, M.; Saito, S.; Oikawa, K.; Maekawa, F.; Futakawa, M.; Kikuchi, K.; Kato, T.; Ikeda, Y.; Naoe, T.; Koyama, T.; Ooi, T.; Zherebtsov, S.; Kawai, M.; Kurishita, H.; Konashi, K.

    2006-09-01

    To develop Ag (silver)-In (indium)-Cd (cadmium) alloy decoupler, a method is needed to bond the decoupler between Al alloy (Al5083) and the ternary Ag-In-Cd alloy. We found that a better HIP condition was temperature, pressure and holding time at 803 K, 100 MPa and 10 min. for small test pieces ( ϕ22 mm in dia. × 6 mm in height). Hardened layer due to the formation of AlAg 2 was found in the bonding layer, however, the rupture strength of the bonding layer is more than 30 MPa, the calculated design stress. Bonding tests of a large size piece (200 × 200 × 30 mm 3), which simulated the real scale, were also performed according to the results of small size tests. The result also gave good bonding and enough required-mechanical-strength.

  14. High frequency of circulating HBcAg-specific CD8 T cells in hepatitis B infection: a flow cytometric analysis

    PubMed Central

    Matsumura, S; Yamamoto, K; Shimada, N; Okano, N; Okamoto, R; Suzuki, T; Hakoda, T; Mizuno, M; Higashi, T; Tsuji, T

    2001-01-01

    Viral antigen-specific T cells are important for virus elimination. We studied the hepatitis B virus (HBV)-specific T cell response using flow cytometry. Three phases of HBV infection were studied: Group A, HBeAg (+) chronic hepatitis; Group B, HBeAb (+) HBV carrier after seroconversion; and Group C, HBsAb (+) phase. Peripheral T cells were incubated with recombinant HB core antigen (HBcAg), and intracytoplasmic cytokines were analysed by flow cytometry. HBcAg-specific CD4 and CD8 T cells were identified in all three groups and the number of IFN-γpositive T cells was greater than TNF-α-positive T cells. The frequency of IFN-γ-positive CD4 and CD8 T cells was highest in Group C, compared with Groups A and B. No significant difference in the HBcAg-specific T cell response was observed between Group A and Group B. The HBcAg-specific CD8 T cell response was diminished by CD4 depletion, addition of antibody against human leucocyte antigen (HLA) class I, class II or CD40L. Cytokine-positive CD8 T cells without HBcAg stimulation were present at a high frequency (7 of 13 cases) in Group B, but were rare in other groups. HBcAg-specific T cells can be detected at high frequency by a sensitive flow cytometric analysis, and these cells are important for controlling HBV replication. PMID:11472405

  15. Tracer diffusion of Ag in Bi2Sr2Can - 1CunO2n + 4

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Routbort, J. L.

    1994-01-01

    Tracer diffusion of Ag in the c direction of single crystal Bi2Sr2CaCu2Ox (2212), and in dense polycrystalline Bi2Sr2CuOx (2201) and (Bi,Pb)2Sr2Ca2Cu3Ox (2223) has been investigated. Concentration profiles were measured by secondary-ion mass spectrometry and by a radiotracer serial-sectioning technique for the single and polycrystals, respectively. The diffusion coefficients of Ag in the c direction of 2212 at 500 and 600 °C at one atmosphere of oxygen are approximately four orders of magnitude smaller than those previously measured in 2212 polycrystals by [Y. Fang, S. Danyluk, K. C. Goretta, N. Chen, M. Runde, S. J. Rothman, and J. L. Routbort, Appl. Phys. Lett. 60, 2291 (1992)]. The volume diffusivity of 110Ag in 2223 is given by D=6.7×107 exp[(-334±12 kJ/mol/RT] cm2/s at temperatures from 600 to 817 °C, and is not very sensitive to oxygen partial pressure between 103 and 105 Pa at 760 °C. The diffusion coefficient of 110Ag in 2201 is described by D=155 exp[(-196±6 kJ/mol)/RT].

  16. Quench Behavior and Degradation Limit of Ag-sheathed Bi 2Sr2CaCu2Ox Round Wires

    NASA Astrophysics Data System (ADS)

    Ye, Liyang

    High field superconducting magnets are important for scientific research in a variety of disciplines. With nearly field-independent critical current density over a wide range of magnetic field at 4.2 K up to 50 T, Ag-sheathed Bi2Sr2CaCu2Ox (Bi-2212) round wires offer the possibility to generate magnetic fields of 30 T and above. One of the key issues in high field Bi-2212 magnet development is the quench detection and protection. A quench occurs when a part of a superconducting winding, after receiving a small disturbance, enters into the normal (resistive) state, and the event follows with significant temperature rise due to joule heating. An unprotected quench may degrade or even destruct an entire superconducting magnet system. This thesis focuses on experimentally investigating the quench behavior and degradation limit of the state-of-the-art multifilamentary Ag/Bi-2212 round wires to guide the development of Bi-2212 high field magnet, especially the quench detection and protection system. (Abstract shortened by ProQuest.).

  17. Spectroscopic investigations of Er3+ :CdO-Bi2 O3-B2O3 glasses.

    PubMed

    Nageswara Raju, C; Adinarayana Reddy, C; Sailaja, S; Seo, Hyo Jin; Sudhakar Reddy, B

    2012-01-01

    This article reports on the optical properties of Er3+ ions doped CdO-Bi2O3-B2O3 (CdBiB) glasses. The materials were characterized by optical absorption and emission spectra. By using Judd-Ofelt theory, the intensity parameters Ω(λ) (λ = 2, 4, 6) and also oscillatory strengths were calculated from the absorption spectra. The results were used to compute the radiative properties of Er3+ :CdBiB glasses. The concentration quenching and energy transfer from Yb3+ -Er3+ were explained. The stimulated emission cross-section, full width at half maximum (FWHM) and FWHM × σpE values are also calculated for all the Er3+ CdBiB glasses. PMID:21932395

  18. Monodispersed Ag3PO4 nanocrystals loaded on the surface of spherical Bi2MoO6 with enhanced photocatalytic performance.

    PubMed

    Xu, Yang-Sen; Zhang, Wei-De

    2013-01-28

    Spherical Bi(2)MoO(6) nanoarchitectures with scale of 500 nm-2 μm were prepared by a solvothermal reaction using bismuth nitrate and ammonium molybdate as precursors. Ag(3)PO(4) nanoparticles were then deposited onto the surface of Bi(2)MoO(6)via a facile deposition-precipitation technique. The photocatalytic tests display that the Ag(3)PO(4)/Bi(2)MoO(6) nanocomposites possess a much higher rate for degradation of rhodamine B and methylene blue than the pure Ag(3)PO(4) nanoparticles and Bi(2)MoO(6) under visible light. The catalytic activity of the composite photocatalysts is greatly influenced by the loading level of Ag(3)PO(4). The 50 mol% Ag(3)PO(4)-loaded Bi(2)MoO(6) spheres exhibit the highest photocatalytic activity in both the decolorization of RhB and MB. The observed improvement in photocatalytic activity is associated with the extended absorption in the visible light region resulting from the Ag(3)PO(4) nanoparticles, and the effective separation of photogenerated carriers at the Ag(3)PO(4)/Bi(2)MoO(6) interfaces. In addition, the composite can be easily reclaimed by sedimentation without any loss of its stability. Moreover, the tests of radical scavengers confirmed that h(+) and ˙OH were the main reactive species for the degradation of RhB. PMID:23131725

  19. 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

  20. Band Gaps of the Lead-Free Halide Double Perovskites Cs2BiAgCl6 and Cs2BiAgBr6 from Theory and Experiment.

    PubMed

    Filip, Marina R; Hillman, Samuel; Haghighirad, Amir Abbas; Snaith, Henry J; Giustino, Feliciano

    2016-07-01

    The recent discovery of lead-free halide double perovskites with band gaps in the visible represents an important step forward in the design of environmentally friendly perovskite solar cells. Within this new family of semiconductors, Cs2BiAgCl6 and Cs2BiAgBr6 are stable compounds crystallizing in the elpasolite structure. Following the recent computational discovery and experimental synthesis of these compounds, a detailed investigation of their electronic properties is warranted in order to establish their potential as optoelectronic materials. In this work, we perform many-body perturbation theory calculations and obtain high accuracy band gaps for both compounds. In addition, we report on the synthesis of Cs2BiAgBr6 single crystals, which are stable in ambient conditions. From our complementary theoretical and experimental analysis, we are able to assign the indirect character of the band gaps and obtain both experimental and theoretical band gaps of these novel semiconductors that are in close agreement. PMID:27322413

  1. Quench degradation limit of multifilamentary Ag/Bi2Sr2CaCu2O x round wires

    NASA Astrophysics Data System (ADS)

    Ye, Liyang; Li, Pei; Shen, Tengming; Schwartz, Justin

    2016-03-01

    Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density J c degradation in commercial Ag/Bi2Sr2CaCu2O x (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. J c degradation strongly depends on the local hot spot temperature T max, and is nearly independent of operating current, the temperature gradient along the conductor dT max/dx, and the temperature rising rate dT max/dt. Both J c and n value (where n is an index of the sharpness of the superconductor-to-normal transition) exhibit small but irreversible degradation when T max exceeds 400-450 K, and large degradation occurs when T max exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt process and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a J c(4.2 K, self field) exceeding 8000 A mm-2, and a wire that has nearly no filament to filament bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced I c degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.

  2. Quench degradation limit of multifilamentary AgBi2Sr2CaCu2Ox round wires

    DOE PAGESBeta

    Ye, Liyang; Li, Pei; Shen, Tengming; Schwartz, Justin

    2016-02-02

    Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density Jc degradation in commercial Ag/Bi2Sr2CaCu2Ox (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. Jc degradation strongly depends on the local hot spot temperature Tmax, and is nearly independent of operating current, the temperature gradient along the conductor dTmax/dx, and the temperature rising rate dTmax/dt. Both Jc and n value (where n is an index of the sharpness of the superconductor-to-normal transition) exhibit small butmore » irreversible degradation when Tmax exceeds 400-450 K, and large degradation occurs when Tmax exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt processing and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a Jc(4.2 K, self field) exceeding 8000 A/mm2, and a wire that has nearly no filament to filament bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced Ic degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.« less

  3. Bi20 (fBTA05), a novel trifunctional bispecific antibody (anti-CD20 x anti-CD3), mediates efficient killing of B-cell lymphoma cells even with very low CD20 expression levels.

    PubMed

    Stanglmaier, Michael; Faltin, Margot; Ruf, Peter; Bodenhausen, Annette; Schröder, Petra; Lindhofer, Horst

    2008-09-01

    Trifunctional bispecific antibodies can efficiently mediate tumor cell killing by redirecting T cells and immune accessory cells to the tumor cell. Here, we describe the new trifunctional antibody, Bi20 (FBTA05, anti-CD20 x anti-CD3), that connects B cells and T cells via its variable regions and recruits FcgammaRI(+) accessory immune cells via its Fc region. Bi20 mediated efficient and specific lysis of B-cell lines and of B cells with low CD20 expression levels that were derived from CLL patients. Remarkably, T-cell activation and tumor cell killing occurred in an entirely autologous setting without additional effector cells in 5 of 8 samples. In comparison, rituximab, a chimeric monoclonal CD20 antibody, demonstrated a significantly lower B-cell eradication rate. Additionally, Bi20, but not rituximab, upregulated the activation markers CD25 and CD69 on both CD4(+) and CD8(+) T cells in the presence of accessory immune cells. CD14(+) accessory cells and the monocyte cell line THP-1 were activated via binding of the Fc region of Bi20, given that T cells were simultaneously engaged by the antibody. Bi20 induced a strong Th1 cytokine pattern characterized by high IFN-gamma and very low IL-4 secretion. In conclusion, Bi20 may offer new immunotherapeutic options for the treatment of B-cell lymphomas. PMID:18546289

  4. Fabrication of novel Ag3PO4/BiOBr heterojunction with high stability and enhanced visible-light-driven photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Mehraj, Owais; Mir, Niyaz A.; Pirzada, Bilal M.; Sabir, Suhail

    2015-03-01

    Herein, we report a facile and effective method to enhance the photocatalytic activity of bismuth oxybromide (BiOBr) semiconductor through the fabrication of heterojunction with Ag3PO4. The as synthesized Ag3PO4/BiOBr microspheres were characterized with transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and UV-vis diffuse reflectance spectroscopy (DRS). The new Ag3PO4/BiOBr heterojunctions exhibited wide absorption in the visible-light region and compared to pure BiOBr and Ag3PO4 samples displayed exceptionally high photocatalytic activity for the degradation of typical organic pollutants such as Rhodamine B (RhB) and phenol. The optimal Ag/Bi weight ratio in Ag3PO4/BiOBr microsphere (AB7) was found to be 0.7. The enhanced photocatalytic activity was related to the efficient separation of electron-hole pairs derived from matching band potentials between BiOBr and Ag3PO4 which results into the generation of natural energy bias at heterojunction and subsequent transfer of photoinduced charge carriers. Moreover, the synthesized samples exhibited almost no loss of activity even after 6 recycling runs indicating their high photocatalytic stability. Considering the facile and environment friendly route for the synthesis of Ag3PO4/BiOBr hybrids with enhanced visible-light induced photocatalytic activity, it is possible to widely apply these hybrids in various fields such as waste water treatment.

  5. Effect of Indium Content on the Melting Point, Dross, and Oxidation Characteristics of Sn-2Ag-3Bi-xIn Solders.

    PubMed

    Jeon, Ae-Jeong; Kim, Seong-Jun; Lee, Sang-Hoon; Kang, Chung-Yun

    2013-06-01

    This paper presents the effect of indium (In) content on the melting temperature, wettabililty, dross formation, and oxidation characteristics of the Sn-2Ag-3Bi-xIn alloy. The melting temperature of the Sn-2Ag-3Bi-xIn alloy (2 ≤ x ≤ 6) was lower than 473 K. The melting range between the solidus and liquidus temperatures was approximately 20 K, irrespective of the indium content. As the indium content increased, the wetting time increased slightly and the maximum wetting force remained to be mostly constant. The dross formation decreased to approximately 50% when adding 1In to Sn-2Ag-3Bi, and no dross formation was observed in the case of Sn-2Ag-3Bi-xIn alloy (x ≥ 1.5) at 523 K for 180 min. Upon approaching the inside of the oxidized solder of the Sn-2Ag-3Bi-1.5In alloy from the surface, the O and In contents decreased and the Sn content increased based on depth profiling analysis using Auger electron spectroscopy (AES). The mechanism for restraining dross (Sn oxidation) of Sn-2Ag-3Bi alloy with addition of indium may be due to surface segregation of indium. This is due to the lower formation energy of indium oxide than those of Sn oxidation. PMID:24891810

  6. Origin of the Order-Disorder Transition and the Associated Anomalous Change of Thermopower in AgBiS2 Nanocrystals: A Combined Experimental and Theoretical Study.

    PubMed

    Guin, Satya N; Banerjee, Swastika; Sanyal, Dirtha; Pati, Swapan K; Biswas, Kanishka

    2016-06-20

    Bulk AgBiS2 crystallizes in a trigonal crystal structure (space group, P3̅m1) at room temperature, which transforms to a cation disordered rock salt structure (space group, Fm3̅m) at ∼473 K. Surprisingly, at room temperature, a solution-grown nanocrystal of AgBiS2 crystallizes in a metastable Ag/Bi ordered cubic structure, which transforms to a thermodynamically stable disorded cubic structure at 610 K. Moreover, the order-disorder transition in nanocrystalline AgBiS2 is associated with an unusual change in thermopower. Here, we shed light on the origin of a order-disorder phase transition and the associated anomalous change of thermopower in AgBiS2 nanocrystals by using a combined experimental, density functional theory based first-principles calculation and ab initio molecular dynamics simulations. Positron-annilation spectroscopy indicates the presence of higher numbers of Ag vacancies in the nanocrystal compared to that of the bulk cubic counterpart at room temperature. Furthermore, temperature-dependent two-detector coincidence Doppler broadening spectroscopy and Doppler broadening of the annihilation radiation (S parameter) indicate that the Ag vacancy concentration increases abruptly during the order-disorder transition in nanocrystalline AgBiS2. At high temperature, a Ag atom shuttles between the vacancy and interstitial sites to form a locally disordered cation sublattice in the nanocrystal, which is facilitated by the formation of more Ag vacancies during the phase transition. This process increases the entropy of the system at higher vacancy concentration, which, in turn, results in the unusual rise in thermopower. PMID:27276279

  7. Studies of porosity, connectivity, and parasitic phases in textured Bi-2212/Ag after non-melt heat treatments

    NASA Astrophysics Data System (ADS)

    Lu, F.; Damborsky, K.; McIntyre, P.; McInturff, A.; Pogue, N.; Smit, Klaus; Sooby, E.

    2012-06-01

    Specimens of cold-pressed, highly textured Bi-2212 powders were subjected to sintering heat treatments to evaluate the impact of sintering upon texture, density, connectivity, microstructure, and growth of parasitic phases. A regime of non-melt sintering parameters were identified that produce near-solid density, strong texture, extensive growth of the Bi-2212 phase in the textured a-b planes, and no significant growth of parasitic phases. This favorable regime is stable over a sintering temperature range from 865°C - 875°C. The results establish one element of our strategy for fabrication of highperformance Bi-2212/Ag wire using textured powder in a 'jelly-roll' configuration.

  8. Bending strain characteristics of Ag/Bi(2223) tapes at liquid nitrogen temperature

    NASA Astrophysics Data System (ADS)

    Katagiri, K.; Hiroi, K.; Kasaba, K.; Asoh, T.; Kuroda, T.; Itoh, K.; Wada, H.; Shin, H. S.

    2004-10-01

    Bending strain dependence of critical current, Ic, of Ag/Bi-2223 57 filament tapes was investigated at 77 K and room temperature, RT, using a device invented by Goldacker. The strain where Ic start to degrade steeply at 77 K, 0.48%, was larger than that at RT, 0.36%. This is an indication of an additional pre-compression in filaments to be bent at 77 K compared with that at RT. According to the voltage measurements using multiple taps in the longitudinal direction, the Ic degradation behaviors at both temperatures varied depending on the section in the tape, due presumably to the difference in the crack propagation characteristics associated with the non-uniformity of the micro-structure. The onset strain for Ic degradation was more precisely determined. The degradation characteristics were shifted to the smaller strain in the present result as compared with that obtained by bending tests using G10 sample holders of different bending radius. The difference can be explained by the different thermal history on setting specimens to the holder and the constraints during cooling. The repeated bending tests at 77 K showed that the discrimination between the gradual and steep degradation stages was clear and the degradation was controlled by both the maximum strain and the strain range.

  9. An Evaluation of Prototype Circuit Boards Assembled with a Sn-Ag Bi Solder

    SciTech Connect

    ARTAKI,I.; RAY,U.; REJENT,JEROME A.; VIANCO,PAUL T.

    1999-09-01

    An evaluation was performed which examined the aging of surface mount solder joints assembled with 91.84Sn-3.33Ag-4.83Bi solder. Defect analysis of the as-fabricated test vehicles revealed excellent solderability, good package alignment, and a minimum number of voids. Continuous DC electrical monitoring of the solder joints did not reveal opens during as many as 10,000 thermal cycles (0 C, 100 C). The solder joints exhibited no significant degradation through 2500 cycles, based upon an absence of microstructural damage and sustained shear and pull strengths of chip capacitors and J-leaded solder joints, respectively. Thermal cycles of 5000 and 10,000 resulted in some surface cracking of the solder fillets and coatings. In a few cases, deeper cracks were observed in the thinner reaches of several solder fillets. There was no deformation or cracking in the solder located in the gap between the package I/O and the circuit board pad nor in the interior of the fillets, both locations that would raise concerns of joint mechanical integrity. A drop in the chip capacitor shear strength was attributed to crack growth near the top of the fillet.

  10. Superconducting properties of multilayered Ag/Bi(Pb)-2223 tapes prepared using pretextured monolayered tapes

    NASA Astrophysics Data System (ADS)

    Syamaprasad, U.; Sarma, M. S.; Guruswamy, P.; Pillai, S. G. K.; Warrier, K. G. K.; Damodaran, A. D.

    1997-02-01

    Multilayered Ag/Bi(Pb)-2223 tapes with high critical current densities 0953-2048/10/2/005/img1 have been fabricated using partially heat treated, textured monolayered tapes. Cut sections of the monolayered tapes have been stacked one over the other and folded together using high-purity silver foil and further rolled and heat treated to obtain multilayered tapes of different thickness with an HTS layer thickness varying from 9 to 0953-2048/10/2/005/img2. A comparison of the superconducting properties of the multilayered tapes with those of monolayered tapes prepared under identical heat treatment conditions shows that the 0953-2048/10/2/005/img3 ratio at 77 K is as high as 0.57. The ratio is found to decrease with a decrease in the HTS core thickness of the multilayered tapes. XRD studies of `banana peeled' samples show that the monolayered tapes at the folding stage acquire a good degree of texturing. The relatively high value of the 0953-2048/10/2/005/img3 ratio obtained in the present case compared with those reported by the existing techniques is attributed to the use of pretextured monolayered tapes.

  11. Fast preparation of Bi{sub 2}GeO{sub 5} nanoflakes via a microwave-hydrothermal process and enhanced photocatalytic activity after loading with Ag nanoparticles

    SciTech Connect

    Li, Zhao-Qian; Lin, Xin-Shan; Zhang, Lei; Chen, Xue-Tai; Xue, Zi-Ling

    2012-09-15

    Highlights: ► Bi{sub 2}GeO{sub 5} nanoflakes were successfully synthesized via a microwave-assisted solution-phase approach. ► Ag nanoparticles were deposited on the Bi{sub 2}GeO{sub 5} nanoflakes by a photoreduction procedure. ► Catalytic activity of the Ag/Bi{sub 2}GeO{sub 5} nanocomposite in the photo-degradation of rhodamine B (RhB) was much higher than that of pure Bi{sub 2}GeO{sub 5}. -- Abstract: In this work, a facile and rapid microwave-assisted hydrothermal route has been developed to prepare Bi{sub 2}GeO{sub 5} nanoflakes. Ag nanoparticles were subsequently deposited on the Bi{sub 2}GeO{sub 5} nanoflakes by a photoreduction procedure. The phases and morphologies of the products were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectroscopy. Photocatalytic experiments indicate that such Ag/Bi{sub 2}GeO{sub 5} nanocomposite possesses higher photocatalytic activity for RhB degradation under UV light irradiation in comparison to pure Bi{sub 2}GeO{sub 5}. The amount of Ag in the nanocomposite affects the catalytic activity, and 3 wt% Ag showed the highest photodegradation efficiency. Moreover, the catalyst remains active after four consecutive tests. The present study provides a new strategy to design composite materials with enhanced photocatalytic activity.

  12. Approaching the N=82 shell closure with mass measurements of Ag and Cd isotopes

    SciTech Connect

    Breitenfeldt, M.; Baruah, S.; Rosenbusch, M.; Schweikhard, L.; Borgmann, Ch.; Boehm, Ch.; George, S.; Audi, G.; Lunney, D.; Minaya-Ramirez, E.; Naimi, S.; Beck, D.; Dworschak, M.; Herfurth, F.; Savreux, R.; Yazidjian, C.; Blaum, K.; Cakirli, R. B.; Casten, R. F.; Delahaye, P.

    2010-03-15

    Mass measurements of neutron-rich Cd and Ag isotopes were performed with the Penning trap mass spectrometer ISOLTRAP. The masses of {sup 112,114-124}Ag and {sup 114,120,122-124,126,128}Cd, determined with relative uncertainties between 2x10{sup -8} and 2x10{sup -7}, resulted in significant corrections and improvements of the mass surface. In particular, the mass of {sup 124}Ag was previously unknown. In addition, other masses that had to be inferred from Q values of nuclear decays and reactions have now been measured directly. The analysis includes various mass differences, namely the two-neutron separation energies, the applicability of the Garvey-Kelson relations, double differences of masses deltaV{sub pn}, which give empirical proton-neutron interaction strengths, as well as a comparison with recent microscopic calculations. The deltaV{sub pn} results reveal that for even-even nuclides around {sup 132}Sn the trends are similar to those in the {sup 208}Pb region.

  13. T-cell ligands modulate the cytolytic activity of the CD33/CD3 BiTE antibody construct, AMG 330

    PubMed Central

    Laszlo, G S; Gudgeon, C J; Harrington, K H; Walter, R B

    2015-01-01

    Preclinical and emerging clinical studies demonstrate that bispecific T-cell engaging (BiTE) antibody constructs can potently lyse targeted tumor cells, but the determinants for their activity remain incompletely understood. Using human acute myeloid leukemia (AML) cell lines engineered to overexpress individual T-cell ligands, we found that expression of the inhibitory ligands, PD-L1 and PD-L2, reduced the cytolytic activity of the BiTE antibody construct targeting CD33, AMG 330; conversely, expression of the activating ligands, CD80 and CD86, augmented the cytotoxic activity of AMG 330. Consistent with these findings, treatment with an activating antibody directed at the co-stimulatory T-cell receptor, CD28, significantly increased AMG 330-induced cytotoxicity in human AML cell lines. Using specimens from 12 patients with newly diagnosed or relapsed/refractory AML, we found that activation of CD28 also increased the activity of AMG 330 in primary human AML cells (P=0.023). Together, our findings indicate that T-cell ligands and co-receptors modulate the anti-tumor activity of the CD33/CD3 BiTE antibody construct, AMG 330. These findings suggest that such ligands/co-receptors could serve as biomarkers of response and that co-treatment strategies with pharmacological modulators of T-cell receptor signaling could be utilized to further enhance the activity of this targeted therapeutic. PMID:26295610

  14. T-cell ligands modulate the cytolytic activity of the CD33/CD3 BiTE antibody construct, AMG 330.

    PubMed

    Laszlo, G S; Gudgeon, C J; Harrington, K H; Walter, R B

    2015-01-01

    Preclinical and emerging clinical studies demonstrate that bispecific T-cell engaging (BiTE) antibody constructs can potently lyse targeted tumor cells, but the determinants for their activity remain incompletely understood. Using human acute myeloid leukemia (AML) cell lines engineered to overexpress individual T-cell ligands, we found that expression of the inhibitory ligands, PD-L1 and PD-L2, reduced the cytolytic activity of the BiTE antibody construct targeting CD33, AMG 330; conversely, expression of the activating ligands, CD80 and CD86, augmented the cytotoxic activity of AMG 330. Consistent with these findings, treatment with an activating antibody directed at the co-stimulatory T-cell receptor, CD28, significantly increased AMG 330-induced cytotoxicity in human AML cell lines. Using specimens from 12 patients with newly diagnosed or relapsed/refractory AML, we found that activation of CD28 also increased the activity of AMG 330 in primary human AML cells (P=0.023). Together, our findings indicate that T-cell ligands and co-receptors modulate the anti-tumor activity of the CD33/CD3 BiTE antibody construct, AMG 330. These findings suggest that such ligands/co-receptors could serve as biomarkers of response and that co-treatment strategies with pharmacological modulators of T-cell receptor signaling could be utilized to further enhance the activity of this targeted therapeutic. PMID:26295610

  15. β-CD Dimer-immobilized Ag Assembly Embedded Silica Nanoparticles for Sensitive Detection of Polycyclic Aromatic Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Hahm, Eunil; Jeong, Daham; Cha, Myeong Geun; Choi, Jae Min; Pham, Xuan-Hung; Kim, Hyung-Mo; Kim, Hwanhee; Lee, Yoon-Sik; Jeong, Dae Hong; Jung, Seunho; Jun, Bong-Hyun

    2016-05-01

    We designed a β-CD dimer on silver nanoparticles embedded with silica nanoparticles (Ag@SiO2 NPs) structure to detect polycyclic aromatic hydrocarbons (PAHs). Silica NPs were utilized as a template for embedding silver NPs to create hot spot structures and enhance the surface-enhanced Raman scattering (SERS) signal, and a thioether-bridged dimeric β-CD was immobilized on Ag NPs to capture PAHs. The assembled Ag NPs on silica NPs were confirmed by TEM and the presence of β-CD dimer on Ag@SiO2 was confirmed by UV-vis and attenuated total reflection-Fourier transform infrared spectroscopy. The β-CD dimer@Ag@SiO2 NPs were used as SERS substrate for detecting perylene, a PAH, directly and in a wide linearity range of 10‑7 M to 10‑2 M with a low detection limit of 10‑8 M. Also, the β-CD dimer@Ag@SiO2 NPs exhibited 1000-fold greater sensitivity than Ag@SiO2 NPs in terms of their perylene detection limit. Furthermore, we demonstrated the possibility of detecting various PAH compounds using the β-CD dimer@Ag@SiO2 NPs as a multiplex detection tool. Various PAH compounds with the NPs exhibited their distinct SERS bands by the ratio of each PAHs. This approach of utilizing the assembled structure and the ligands to recognize target has potential for use in sensitive analytical sensors.

  16. β-CD Dimer-immobilized Ag Assembly Embedded Silica Nanoparticles for Sensitive Detection of Polycyclic Aromatic Hydrocarbons.

    PubMed

    Hahm, Eunil; Jeong, Daham; Cha, Myeong Geun; Choi, Jae Min; Pham, Xuan-Hung; Kim, Hyung-Mo; Kim, Hwanhee; Lee, Yoon-Sik; Jeong, Dae Hong; Jung, Seunho; Jun, Bong-Hyun

    2016-01-01

    We designed a β-CD dimer on silver nanoparticles embedded with silica nanoparticles (Ag@SiO2 NPs) structure to detect polycyclic aromatic hydrocarbons (PAHs). Silica NPs were utilized as a template for embedding silver NPs to create hot spot structures and enhance the surface-enhanced Raman scattering (SERS) signal, and a thioether-bridged dimeric β-CD was immobilized on Ag NPs to capture PAHs. The assembled Ag NPs on silica NPs were confirmed by TEM and the presence of β-CD dimer on Ag@SiO2 was confirmed by UV-vis and attenuated total reflection-Fourier transform infrared spectroscopy. The β-CD dimer@Ag@SiO2 NPs were used as SERS substrate for detecting perylene, a PAH, directly and in a wide linearity range of 10(-7) M to 10(-2) M with a low detection limit of 10(-8) M. Also, the β-CD dimer@Ag@SiO2 NPs exhibited 1000-fold greater sensitivity than Ag@SiO2 NPs in terms of their perylene detection limit. Furthermore, we demonstrated the possibility of detecting various PAH compounds using the β-CD dimer@Ag@SiO2 NPs as a multiplex detection tool. Various PAH compounds with the NPs exhibited their distinct SERS bands by the ratio of each PAHs. This approach of utilizing the assembled structure and the ligands to recognize target has potential for use in sensitive analytical sensors. PMID:27184729

  17. β-CD Dimer-immobilized Ag Assembly Embedded Silica Nanoparticles for Sensitive Detection of Polycyclic Aromatic Hydrocarbons

    PubMed Central

    Hahm, Eunil; Jeong, Daham; Cha, Myeong Geun; Choi, Jae Min; Pham, Xuan-Hung; Kim, Hyung-Mo; Kim, Hwanhee; Lee, Yoon-Sik; Jeong, Dae Hong; Jung, Seunho; Jun, Bong-Hyun

    2016-01-01

    We designed a β-CD dimer on silver nanoparticles embedded with silica nanoparticles (Ag@SiO2 NPs) structure to detect polycyclic aromatic hydrocarbons (PAHs). Silica NPs were utilized as a template for embedding silver NPs to create hot spot structures and enhance the surface-enhanced Raman scattering (SERS) signal, and a thioether-bridged dimeric β-CD was immobilized on Ag NPs to capture PAHs. The assembled Ag NPs on silica NPs were confirmed by TEM and the presence of β-CD dimer on Ag@SiO2 was confirmed by UV-vis and attenuated total reflection-Fourier transform infrared spectroscopy. The β-CD dimer@Ag@SiO2 NPs were used as SERS substrate for detecting perylene, a PAH, directly and in a wide linearity range of 10−7 M to 10−2 M with a low detection limit of 10−8 M. Also, the β-CD dimer@Ag@SiO2 NPs exhibited 1000-fold greater sensitivity than Ag@SiO2 NPs in terms of their perylene detection limit. Furthermore, we demonstrated the possibility of detecting various PAH compounds using the β-CD dimer@Ag@SiO2 NPs as a multiplex detection tool. Various PAH compounds with the NPs exhibited their distinct SERS bands by the ratio of each PAHs. This approach of utilizing the assembled structure and the ligands to recognize target has potential for use in sensitive analytical sensors. PMID:27184729

  18. Metal-Semiconductor Hybrid Aerogels: Evolution of Optoelectronic Properties in a Low-Dimensional CdSe/Ag Nanoparticle Assembly.

    PubMed

    Nahar, Lamia; Esteves, Richard J Alan; Hafiz, Shopan; Özgür, Ümit; Arachchige, Indika U

    2015-10-27

    Hybrid nanomaterials composed of metal-semiconductor components exhibit unique properties in comparison to their individual counterparts, making them of great interest for optoelectronic applications. Theoretical and experimental studies suggest that interfacial interactions of individual components are of paramount importance to produce hybrid electronic states. The direct cross-linking of nanoparticles (NPs) via controlled removal of the surfactant ligands provides a route to tune interfacial interactions in a manner that has not been thoroughly investigated. Herein, we report the synthesis of CdSe/Ag heteronanostructures (aerogels) via oxidation induced self-assembly of thiol-coated NPs and the evolution of optical properties as a function of composition. Three hybrid systems were investigated, where the first and second excitonic energies of CdSe were matched with plasmonic energy of Au or Ag NPs and Ag hollow NPs. Physical characterization of the aerogels suggests the presence of an interconnected network of hexagonal CdSe and cubic Ag NPs. The optical properties of hybrids were systematically examined through UV-vis, photoluminescence (PL), and time-resolved (TR) PL spectroscopic studies that indicate the generation of alternate radiative decay pathways. A new emission (640 nm) from CdSe/Ag aerogels emerged at Ag loading as low as 0.27%, whereas absorption band tailing and PL quenching effects were observed at higher Ag and Au loading, respectively. The TRPL decay time of the new emission (∼600 ns) is markedly different from those of the band-edge (1.83 ± 0.03 ns) and trap-state (1190 ± 120 ns) emission maxima of phase pure CdSe, supporting the existence of alternate radiative relaxation pathways in sol-gel derived CdSe/Ag hybrids. PMID:26389642

  19. New chalcogenide glasses in the CdTe-AgI-As{sub 2}Te{sub 3} system

    SciTech Connect

    Kassem, M.; Le Coq, D.; Boidin, R.; Bychkov, E.

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Determination of the glass-forming region in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system. Black-Right-Pointing-Pointer Characterization of macroscopic properties of the new CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Characterization of the total conductivity of CdTe-AgI-As{sub 2}Te{sub 3} glasses. Black-Right-Pointing-Pointer Comparison between the selenide and telluride equivalent systems. -- Abstract: Chalcogenide glasses in the pseudo-ternary CdTe-AgI-As{sub 2}Te{sub 3} system were synthesized and the glass-forming range was determined. The maximum content of CdTe in this glass system was found to be equal to 15 mol.%. The macroscopic characterizations of samples have consisted in Differential Scanning Calorimetry, density, and X-ray diffraction measurements. The cadmium telluride addition does not generate any significant change in the glass transition temperature but the resistance of binary AgI-As{sub 2}Te{sub 3} glasses towards crystallisation is estimated to be decreasing on the base of {Delta}T = T{sub x} - T{sub g} parameter. The total electrical conductivity {sigma} was measured by complex impedance spectroscopy. First, the CdTe additions in the (AgI){sub 0.5}(As{sub 2}Te{sub 3}){sub 0.5} host glass, (CdTe){sub x}(AgI){sub 0.5-x/2}(As{sub 2}Te{sub 3}){sub 0.5-x/2} lead to a conductivity decrease at x {<=} 0.05. Then, the behaviour is reversed at 0.05 {<=} x {<=} 0.15. The obtained results are discussed by comparison with the equivalent selenide system.

  20. α-Radioimmunotherapy with 213Bi-anti-CD38 immunoconjugates is effective in a mouse model of human multiple myeloma

    PubMed Central

    Blechert, Birgit; Gaertner, Florian C.; Gilbertz, Klaus-Peter; Fernandez, Vanesa; Bassermann, Florian; Endell, Jan; Boxhammer, Rainer; Leclair, Stephane; Vallon, Mario; Aichler, Michaela; Feuchtinger, Annette; Bruchertseifer, Frank; Morgenstern, Alfred; Essler, Markus

    2015-01-01

    In spite of development of molecular therapeutics, multiple myeloma (MM) is fatal in most cases. CD38 is a promising target for selective treatment of MM. We tested radioimmunoconjugates consisting of the α-emitter 213Bi coupled to an anti-CD38 MAb in preclinical treatment of MM. Efficacy of 213Bi-anti-CD38-MAb was assayed towards different MM cell lines with regard to induction of DNA double-strand breaks, induction of apoptosis and initiation of cell cycle arrest. Moreover, mice bearing luciferase-expressing MM xenografts were treated with 213Bi-anti-CD38-MAb. Therapeutic efficacy was monitored by bioluminescence imaging, overall survival and histology. 213Bi-anti-CD38-MAb treatment induced DNA damage which did not result in activation of the G2 DNA-damage-response checkpoint, but instead in mitotic arrest and subsequent mitotic catastrophe. The anti-tumor effect of 213Bi-anti-CD38-MAb correlated with the expression level of CD38 in each MM cell line. In myeloma xenografts, treatment with 213Bi-anti-CD38-MAb suppressed tumor growth via induction of apoptosis in tumor tissue and significantly prolonged survival compared to controls. The major organ systems did not show any signs of 213Bi-induced toxicity. Preclinical treatment of MM with 213Bi-anti-CD38-MAb turned out as an effective therapeutic option. PMID:25576914

  1. Ag-SHEATHED Bi2Sr2CaCu2O8 Square Wire Insulated with Oxidized Hastelloy Fiber Braid

    NASA Astrophysics Data System (ADS)

    Watanabe, K.; Nishijima, G.; Awaji, S.; Hikichi, Y.; Hasegawa, T.

    2008-03-01

    Oxidized Hastelloy X (Hx) fiber braid has been demonstrated to work well as a good electric insulation of Ag-sheathed Bi2Sr2CaCu2O8 (Ag/Bi2212) wires. In order to develop a wind-and-react processed Ag/Bi2212 superconducting magnet with a high coil current density, we fabricated a test coil employing 45 m long Ag/Bi2212 square shape wire with 50 μm Hx fiber braid. A test coil, whose size is 73 mm outer diameter, 64.5 mm inner diameter, and 74 mm coil winding height, consisted of 4 layers and 210 turns, and was heat-treated at around 890 °C in oxygen gas. The critical current Ic of the test coil was 245 A at 4.2 K in a self-field, corresponding to a 67% value of the short sample Ic heat-treated at the same time for comparison. Coil inductance was calculated to be 1.9 mH, and as a result, the same inductance value was obtained in the test coil. It was found that a Hx cloth knitting method enables us to insulate sufficiently between wires in Ag/Bi2212 square shape wire.

  2. Three-dimensional Dirac cone carrier dynamics in Na3Bi and Cd3As2

    NASA Astrophysics Data System (ADS)

    Jenkins, G. S.; Lane, C.; Barbiellini, B.; Sushkov, A. B.; Carey, R. L.; Liu, Fengguang; Krizan, J. W.; Kushwaha, S. K.; Gibson, Q.; Chang, Tay-Rong; Jeng, Horng-Tay; Lin, Hsin; Cava, R. J.; Bansil, A.; Drew, H. D.

    2016-08-01

    Optical measurements and band structure calculations are reported on three-dimensional Dirac materials. The electronic properties associated with the Dirac cone are identified in the reflectivity spectra of Cd3As2 and Na3Bi single crystals. In Na3Bi , the plasma edge is found to be strongly temperature dependent due to thermally excited free carriers in the Dirac cone. The thermal behavior provides an estimate of the Fermi level EF=25 meV and the z -axis Fermi velocity vz=0.3 eV Å associated with the heavy bismuth Dirac band. At high energies above the Γ -point Lifshitz gap energy, a frequency- and temperature-independent ɛ2 indicative of Dirac cone interband transitions translates into an ab-plane Fermi velocity of 3 eV Å. The observed number of IR phonons rules out the P 63/m m c space-group symmetry but is consistent with the P 3 ¯c 1 candidate symmetry. A plasmaron excitation is discovered near the plasmon energy that persists over a broad range of temperature. The optical signature of the large joint density of states arising from saddle points at Γ is strongly suppressed in Na3Bi , consistent with band structure calculations that show the dipole transition-matrix elements to be weak due to the very small s -orbital character of the Dirac bands. In Cd3As2 , a distinctive peak in reflectivity due to the logarithmic divergence in ɛ1 expected at the onset of Dirac cone interband transitions is identified. The center frequency of the peak shifts with temperature quantitatively consistent with a linear dispersion and a carrier density of n =1.3 ×1017cm-3 . The peak width gives a measure of the Fermi-velocity anisotropy of 10 % , indicating a nearly spherical Fermi surface. The line shape gives an upper bound estimate of 7 meV for the potential fluctuation energy scale.

  3. Generation of intense and cold beam of Pt-Ag bi-element cluster ions having single-composition

    NASA Astrophysics Data System (ADS)

    Yasumatsu, H.

    2011-07-01

    An intense beam of bi-element Pt-Ag cluster ions with a single atomic-composition has been gained toward development of new-functional materials of the clusters fixed on a solid surface. Mass production of the bi-element cluster ions has been achieved by operating dual magnetron-sputtering devices independently in a gas aggregation cell, and the ions having a single composition are filtered out by passing through a quadrupole mass filter. The kinetic energies of the cluster ions have been reduced by collision with cold helium in order for low-energy cluster-impact deposition of the clusters on the surface. The cooling process was examined further by means of molecular-dynamics simulation.

  4. Metal coordination study at Ag and Cd sites in crown thioether complexes through DFT calculations and hyperfine parameters.

    PubMed

    do Nascimento, Rafael R; Lima, Filipe C D A; Gonçalves, Marcos B; Errico, Leonardo A; Rentería, Mario; Petrilli, Helena M

    2015-04-01

    Structural and electronic properties of [C12H24S6X], [C13H26S6OX], and [C14H28S6OX] (X: Ag(+), Cd(2+)) crown thioether complexes were investigated within the framework of the density functional theory (DFT) using the projector augmented wave (PAW) method. The theoretical results were compared with time-differential perturbed γ-γ angular correlations (TDPAC) experiments reported in the literature using the (111)Ag→(111)Cd probe. In the case of X=Ag(+), a refinement of the structure was performed and the predicted equilibrium structures compared with available X-ray diffraction experimental data. Structural distortions induced by replacing Ag(+) with Cd(2+) were investigated as well as the electric-field gradient (EFG) tensor at the Cd(2+) sites. Our results suggest that the EFG at Cd(2+) sites corresponds to the Ag(+) coordination sphere structure, i.e., before the structural relaxations of the molecule with X=Cd(2+) are completed. The results are discussed in terms of the characteristics of the TDPAC (111)Ag→(111)Cd probe and the time window of the measurement, and provide an interesting tool with which to probe molecular relaxations. PMID:25814377

  5. In situ decoration of plasmonic Ag nanocrystals on the surface of (BiO)2CO3 hierarchical microspheres for enhanced visible light photocatalysis.

    PubMed

    Dong, Fan; Li, Qiuyan; Zhou, Ying; Sun, Yanjun; Zhang, Haidong; Wu, Zhongbiao

    2014-07-01

    Novel plasmonic 0D Ag nanocrystal decorated 3D (BiO)2CO3 hierarchical microspheres were fabricated with a one-pot hydrothermal method. The as-prepared samples were systematically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, photoluminescence spectra, ns-level time-resolved fluorescence spectra, photocurrent generation and EIS measurement. The results indicated that the 0D Ag nanoparticles were deposited on the surface of 3D (BiO)2CO3 hierarchical microspheres. The deposited Ag nanoparticles were reduced from Ag(+) by the citrate ions from bismuth citrate. The photocatalytic activity of the as-prepared samples was evaluated towards the degradation of NO at ppb-level under visible light irradiation. The intermediate NO2 was monitored on-line during the photocatalytic reaction. The pure (BiO)2CO3 microspheres exhibited decent visible light photocatalytic activity because of the surface scattering and reflecting (SSR effect) resulting from the special 3D hierarchical architecture. The Ag-decorated (BiO)2CO3 microspheres (Ag/BOC) exhibited greatly enhanced photocatalytic activity, photocurrent generation and promoted NO2 oxidation compared to the pure (BiO)2CO3 microspheres. The enhanced photocatalytic activity and photocurrent generation of Ag/BOC was ascribed to the cooperative contribution of the surface plasmon resonance (SPR effect), efficient separation of electron-hole pairs and prolonged lifetime of charge carriers induced by Ag nanoparticles. The photocatalytic performance of Ag/BOC was dependent on the content of Ag loading. When the amount of Ag is controlled at 5%, the highest photocatalytic performance can be achieved. Further increasing the Ag loading content promotes aggregation of the Ag particles and transforms the uniform microspheres into non-uniform microspheres, which is not beneficial

  6. Enhanced ferroelectric photoelectrochemical properties of polycrystalline BiFeO3 film by decorating with Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Qing; Zhou, Yang; You, Lu; Wang, Junling; Shen, Mingrong; Fang, Liang

    2016-01-01

    Polycrystalline BiFeO3 (BFO) films are fabricated on Pt/Ti/SiO2/Si(100) substrate as photoelectrode using sol-gel method. The microstructure, optical, and photoelectrochemical (PEC) properties of the films are characterized and optimized by controlling the film thickness. Moreover, the PEC properties of the BFO films are dependent on ferroelectric polarization, which is mainly ascribed to the modulation of band structure at the BFO/electrolyte interface by the polarization. Further enhancement of PEC properties is obtained by decorating the samples with appropriate amounts of Ag nanoparticles, which is attributed to the reduced electron-hole recombination, and localized surface plasmon resonance effect of Ag nanoparticles.

  7. Investigate on the application of elliptical drawing dies during the manufacturing process of Bi-2223/Ag superconducting tapes

    NASA Astrophysics Data System (ADS)

    Liu, R.; Qu, T.-M.; Zhang, J.-S.; Song, X.-H.; Liang, T.; Liu, Q.; Han, Z.

    2008-09-01

    Elliptical drawing (ED) dies were used during the manufacturing process of Bi-2223/Ag superconducting tapes and their influence on the tapes’ homogeneity and critical currents ( Ic) has been investigated. By comparing two types of HTS tapes drawn by ED dies and a set of reference round dies, we found that the ED process can improve the qualities of the rolled tapes, such as improving the homogeneity of both the center and the peripheral filaments of the tapes, reducing the micro-cracks caused by the rolling process. Thus, the ED process can increase the Ic and engineering critical current density ( Je) values of HTS tapes.

  8. CdS and AgBr sensitized eriochrome black T (EBT) dye solar cells

    NASA Astrophysics Data System (ADS)

    Sharma, G. D.; Dube, D. C.; Mathur, S. C.

    1985-11-01

    The photovoltaic and rectification properties of CdS- and AgBr-sensitized Eriochrome Black T dye solar cells have been studied. The dependence of the short-circuit current and the open-circuit voltage on light intensity and electrode material are examined and the variations with electrode material are explained on the basis of the built-in potential developed at the metal-semiconductor interface. Conversion efficiency, fill factor, diode factor and reverse saturation current are also calculated for each cell.

  9. Volume dependence of Anderson hybridization in cubic CeCd and CeAg

    SciTech Connect

    Monachesi, P. ); Andreani, L.C. ); Continenza, A. ); McMahan, A.K. )

    1993-05-15

    We have undertaken a first-principles theoretical study of the Anderson hybridization in cubic CeCd and CeAg as a function of volume reduction. We present results for the hybridization width [Delta]([epsilon]) in both the [ital J]=5/2 multiplet and in the [Gamma][sub 8], [Gamma][sub 7] crystal field states of the [ital f][sup 1] Ce configuration. We also calculate the hybridization contribution to the magnetic transition temperature. This is found to increase with pressure but is smaller than the experimental values, indicating that the Coulomb exchange contribution to the magnetic coupling is not negligible in these compounds.

  10. Volume dependence of Anderson hybridization in cubic CeCd and CeAg

    SciTech Connect

    Monachesi, P.; Continenza, A. . Dipt. di Fisica); Andreani, L.C. ); McMahan, A.K. )

    1992-09-01

    We have undertaken a first-principles theoretical study of the Anderson hybridization in cubic CeCd and CeAg as a function of volume reduction. We present results for the hybridization width [Delta]([epsilon]) in both the J = 5/2 multiplet and in the [Gamma][sub 8], [Gamma][sub 7] crystal field states of the f[sup 1] Ce configuration. We also calculate the hybridization contribution to the magnetic transition temperature. This is found to increase with pressure but is smaller than the experimental values, indicating that the Coulomb exchange contribution to the magnetic coupling is not negligible in these compounds.

  11. Volume dependence of Anderson hybridization in cubic CeCd and CeAg

    SciTech Connect

    Monachesi, P.; Continenza, A.; Andreani, L.C.; McMahan, A.K.

    1992-09-01

    We have undertaken a first-principles theoretical study of the Anderson hybridization in cubic CeCd and CeAg as a function of volume reduction. We present results for the hybridization width {Delta}({epsilon}) in both the J = 5/2 multiplet and in the {Gamma}{sub 8}, {Gamma}{sub 7} crystal field states of the f{sup 1} Ce configuration. We also calculate the hybridization contribution to the magnetic transition temperature. This is found to increase with pressure but is smaller than the experimental values, indicating that the Coulomb exchange contribution to the magnetic coupling is not negligible in these compounds.

  12. Influence of reactive sulfide (AVS) and supplementary food on Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata

    USGS Publications Warehouse

    Lee, J.-S.; Lee, B.-G.; Yoo, H.; Koh, C.-H.; Luoma, S.N.

    2001-01-01

    A laboratory bioassay determined the relative contribution of various pathways of Ag, Cd and Zn bioaccumulation in the marine polychaete Neanthes arenaceodentata exposed to moderately contaminated sediments. Juvenile worms were exposed for 25 d to experimental sediments containing 5 different reactive sulfide (acid volatile sulfides, AVS) concentrations (1 to 30 ??mol g-1), but with constant Ag, Cd, and Zn concentrations of 0.1, 0.1 and 7 ??mol g-1, respectively. The sediments were supplemented with contaminated food (TetraMin??) containing 3 levels of Ag-Cd-Zn (uncontaminated, 1?? or 5??1 metal concentrations in the contaminated sediment). The results suggest that bioaccumulation of Ag, Cd and Zn in the worms occurred predominantly from ingestion of contaminated sediments and contaminated supplementary food. AVS or dissolved metals (in porewater and overlying water) had a minor effect on bioaccumulation of the 3 metals in most of the treatments. The contribution to uptake from the dissolved source was most important in the most oxic sediments, with maximum contributions of 8% for Ag, 30% for Cd and 20% for Zn bioaccumulation. Sediment bioassays where uncontaminated supplemental food is added could seriously underestimate metal exposures in an equilibrated system; N. arenaceodentata feeding on uncontaminated food would be exposed to 40-60% less metal than if the food source was equilibrated (as occurs in nature). Overall, the results show that pathways of metal exposure are dynamically linked in contaminated sediments and shift as external geochemical characteristics and internal biological attributes vary.

  13. Forming-free, bi-directional polarity conductive-bridge memory devices with Ge2Sb2Te5 solid-state electrolyte and Ag active electrode

    NASA Astrophysics Data System (ADS)

    Huang, Yin-Hsien; Chen, Hsuan-An; Wu, Hsin-Han; Hsieh, Tsung-Eong

    2015-01-01

    Preparation and characteristics of conductive-bridge random access memory devices containing Ge2Sb2Te5 (GST) chalcogenide as the solid-state electrolyte, Ag as the active electrode, and W-Ti as the counter electrode are presented. As revealed by the electrical measurement, only the samples containing crystalline GST exhibited the resistive switching behaviors. With an insertion of ZnS-SiO2 dielectric layer at the Ag/GST interface and a postannealing at 100 °C for 1 min, the sample exhibited the best electrical performance with satisfactory cycleability and retention properties. Moreover, the forming-free and bi-directional polarity features were observed in such a sample type. Microstructure and composition analyses found the finely dispersed nano-scale Ag clusters in GST and, when electrical bias is applied, the migrating Ag ions may build up the connections in between neighboring Ag clusters. Moreover, grain boundaries in polycrystalline GST might be the main paths for Ag migration. The thread-like conduction channels in GST hence form, leading to the low resistance state of sample. On the contrary, the depletion of Ag in GST broke the connections in between Ag clusters when the electrical bias is reversed. This led to the rupture of conduction channels and, hence, the high resistance state of sample. The low operational voltage, forming-free, and bi-directional polarity features observed in (AZGW)T sample might also originated from the fine dispersion of Ag clusters in GST electrolyte.

  14. Ag/Au bi-metallic film based color surface plasmon resonance biosensor with enhanced sensitivity, color contrast and great linearity.

    PubMed

    Li, Chung-Tien; Lo, Kun-Chi; Chang, Hsin-Yun; Wu, Hsieh-Ting; Ho, Jennifer H; Yen, Ta-Jen

    2012-01-01

    In wavelength surface plasmon resonance (SPR) biosensor, the manipulation of SPR dispersion relation by Ag/Au bi-metallic film was first time implemented. Due to the enhanced resonant wavelength shift and the sharper SPR slope of using Ag/Au bi-metallic film, the illuminated color of reflection shows one order of magnitude greater contrast than conventional SPR biosensors. Such an Ag/Au bi-metallic film based color SPR biosensor (CSPRB) allows the detail bio-interactions, for example 100 nM streptavidin, to be distinguished by directly observing the color change of reflection through naked eyes rather than the analysis of spectrometer. In addition to the enhanced sensitivity and color contrast, this CSPRB also possesses a great linear detection range up to 0.0254 RIU, which leading to the application of point-of-care tests. PMID:22560104

  15. Development of CdO-graphite-Ag coatings for gas bearings to 427 C

    NASA Technical Reports Server (NTRS)

    Bhushan, B.

    1981-01-01

    Graphite is one of the most commonly known lubricants. Its effectiveness in a range between room temperature (RT) and 540 C is reportedly improved by adding cadmium oxide. CdO-graphite powder in a gas carrier has been used in numerous applications that rely on dry lubrication. A coating of this composition was developed and successfully tested in foil air bearings for long periods up to a temperature of 427 C and at a normal contacting load (during starting and stopping) of 14 kPa based on bearing projected area. The addition of ultra-fine silver to the CdO-graphite has improved the coating endurance. At 427 C, the CdO-graphite-Ag coating performed better than CdO-graphite without silver, both for extended periods at 14 kPa loading and for limited periods at 35 kPa. At 288 C, the coating was tested for an extended period up to 28 kPa and has also successfully completed high-speed shock tests to an acceleration level of 100g.

  16. Phase homology in new layered mixed Li, M (M=Mg, Cu, Cd, Pb, Bi) bismuth oxophosphates and oxoarsenates

    NASA Astrophysics Data System (ADS)

    Kozin, M. S.; Colmont, M.; Endara, D.; Aliev, A.; Huvé, M.; Siidra, O. I.; Krivovichev, S. V.; Mentré, O.

    2013-03-01

    Single crystals of two novel bismuth oxocompounds were grown from melts and the corresponding pure powders obtained from solid state reactions. Both compounds were structurally characterized using X-Ray diffraction techniques. [Bi7O7][BiO]7Cd1Li2(PO4)6 (1) is monoclinic, C2/m, a=26.9234(23), b=5.2926(5), c=12.3024(10) Å, β=106.45(5)°, R1=0.042 and ωR2=0.062. The crystal structure of 1 is related to that of [Bi7O7][BiO]7Bii0.66Li2(PO4)6 and consists of the [Bi7O7]7+ tetrahedral layers with the [(BiO)7CdLi2(PO4)6]7- interlayer blocks, where [BiO]+ denotes units attached to the layers of oxocentered tetrahedra. [Bi4O4][BiO]4Cu1Li2(AsO4)4 (2) is monoclinic, P21/c, a=8.8133(4), b=24.346(1), c=5.4056(2) Å, β=106,93(2)°, R1=0.031 and ωR2=0.035. The crystal structure of 2 is based upon layers similar to those observed in 1, but with the modified topology of the interlayer block. Both compounds can be considered as derivatives from the parent δ-Bi2O3 fluorite-like structure, where phosphorus and arsenic atoms substitute for some Bi sites. The arrangement of the [BiO]+ layers and the XO4 (X=P, As) interlayer groups is significantly modified compared to the previously known Cd compound. The comparison and review of the related structures is given. The variety of aliovalent cations able to incorporate in the interlayer as well as the strong structural resemblance with the Aurivillius series compounds establishes the new routes for the further prospective syntheses of novel but related phases with various important applications.

  17. Biological interaction between transition metals (Ag, Cd and Hg), selenide/sulfide and selenoprotein P.

    PubMed

    Sasakura, C; Suzuki, K T

    1998-09-01

    The interaction between transition metals (Ag+, Cd2+ and Hg2+) and selenium (Se) in the bloodstream was studied in vitro by means of the HPLC--inductively coupled argon plasma-mass spectrometry (ICP MS) method. Transition metal ions and selenide (produced in vitro from selenite in the presence of glutathione) or sulfide (Na2S) formed a (metal-Se/S) complex, which then bound to a plasma protein, selenoprotein P (Sel P), to form a ternary complex, (metal-Se/S)-Sel P. The molar ratios of metals to Se were 1:1 for Hg/Se and Cd/Se, but either 1:1 or 2:1 for Ag/Se, depending on the ratio of their doses. The results indicate that the interaction between transition metals and Se occurs through the general mechanism, i.e., transition metal ions and selenide form the unit complex (metal-Se)n, and then the complex binds to selenoprotein P to form the ternary complex ¿(metal-Se)n¿m--seleno-protein P in the bloodstream. PMID:9833321

  18. Availability of sediment-bound Cd, Co, and Ag to mussels

    SciTech Connect

    Gagnon, C.; Fisher, N.S.

    1995-12-31

    Ingested sediment is one potentially important source of metals for benthic organisms. The influence of physical and chemical properties of oxidized sediments on the bioavailability of metals to marine filter feeders is largely unknown. The authors examined the relative importance of specific sedimentary components that may exert control on the uptake of Cd, Co, and Ag in the mussel Mytilus edulis. Iron and manganese oxides, montmorillonite clay, silica, and natural sediment particles were triple labeled with the gamma emitters {sup 109}Cd, {sup 57}Co, and {sup 110m}Ag. Some particles were also coated with fulvic acid (FA) to simulate the influence of organic coating on metal bioavailability. Metals associated with FA-coated particles were generally absorbed by mussels to a greater extent than metals associated with uncoated particles. Desorption experiments with labeled particles at pH 5 were performed in parallel to simulate the behavior of food-bound metals in the acidic gut of bivalves. High correlations (r > 0.97) between the amount of desorbed metal under these conditions and the assimilation efficiency for metals from FA-coated particles were noted among coated particles but not uncoated particles (r < 0.6). These results suggest that the relation between metal partitioning to sediments and biological availability of the metal is not obvious, since the organic coatings and the acidic digestion process influence assimilation of sediment-bound metals.

  19. Fabrication and characterization of high-{Tc} tapes and coils made from Ag-clad Bi-2223 superconductors

    SciTech Connect

    Balachandran, U.; Iyer, A.N.; Youngdahl, C.A.; Motowidlo, L.R.; Hoehn, J.G. Jr.; Haldar, P.

    1993-07-01

    Prereacted Pb-doped Bi-Sr-Ca-Cu-0 powders were packed into Ag tubes, drawn, rolled, and given intermediate heat treatment to prepare long lengths of Ag-clad Bi-2223 superconductor tapes. With the use of improved process conditions, transport critical current density (J{sub c}) values exceeding 10{sup 5} A/cm{sup 2} at 4.2 K and 27 K, and greater than 4 {times} 10{sup 4} A/cm{sup 2} at 77 K, were obtained in zero applied field with short tape samples. Detailed microstructural analysis and J{sub c} measurements in applied fields up to 20 T are reported. Rolled tapes were cut into lengths of up to 10 m, and several such tapes were used in parallel to fabricate small superconducting pancake coils by the ``wind-and-react`` technique. Recently, we fabricated a test magnet with six pancake coils, each containing three 10-m lengths of rolled tapes and tested at 4.2, 27, and 77 K as a function of applied fields up to 14.5 T. A maximum generated field of 1.25 T was measured in zero applied field at 4.2 T. Detailed measurements made on the pancake coils and test magnets are reported in this paper.

  20. 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

  1. Band bending at Al, In, Ag, and Pt interfaces with CdTe and ZnTe (110)

    NASA Technical Reports Server (NTRS)

    Wahi, A. K.; Miyano, K.; Carey, G. P.; Chiang, T. T.; Lindau, I.

    1990-01-01

    UV and X-ray photoelectron spectroscopic methods are presently used to study the band-bending behavior and interfacial chemistry of Al, In, Ag, and Pt overlayers on vacuum-cleaved p-CdTe and p-ZnTe (110). All four metals are found to yield Schottky barriers on CdTe and ZnTe. The metal-induced gap states model prediction of a difference in barrier heights for two semiconductors which is dependent on their band lineup is borne out by the results for Ag, Pt, and Al, but not for In. Reaction and intermixing for Al, Ag, and Pt overlayers on CdTe and ZnTe indicate that these interfaces are not ideal.

  2. Fabrication of a Ag/Bi3TaO7 Plasmonic Photocatalyst with Enhanced Photocatalytic Activity for Degradation of Tetracycline.

    PubMed

    Luo, Bifu; Xu, Dongbo; Li, Di; Wu, Guoling; Wu, Miaomiao; Shi, Weidong; Chen, Min

    2015-08-12

    A novel Ag/Bi3TaO7 plasmonic photocatalyst has been prepared by a simple photoreduction process. The as-prepared Ag/Bi3TaO7 photocatalyst exhibited an enhanced photocatalytic activity for the degradation of tetracycline (TC) compared to that of a bare Bi3TaO7 catalyst. The 1 wt % Ag-loaded Bi3TaO7 sample showed the highest photocatalytic efficiency for TC degradation (85.42%) compared with those of the other samples. The enhanced photocatalytic activity could be ascribed to the synergistic effect of the surface plasmon resonance caused by Ag nanoparticles. Electrochemical impedance spectroscopy demonstrated that the incorporation of silver nanoparticles onto the Bi3TaO7 surface promoted the separation of photogenerated carriers. In addition, an electron spin resonance (ESR) and trapping experiment revealed that the photoinduced active species hydroxyl radical and superoxide radical were the main active species in the photocatalytic process of TC degradation. The photocatalytic reaction mechanism was discussed by active species trapping and ESR analysis. PMID:26167624

  3. Decitabine enhances anti-CD33 monoclonal antibody BI 836858-mediated natural killer ADCC against AML blasts.

    PubMed

    Vasu, Sumithira; He, Shun; Cheney, Carolyn; Gopalakrishnan, Bhavani; Mani, Rajeswaran; Lozanski, Gerard; Mo, Xiaokui; Groh, Veronica; Whitman, Susan P; Konopitzky, Renate; Kössl, Christian; Bucci, Donna; Lucas, David M; Yu, Jianhua; Caligiuri, Michael A; Blum, William; Adam, Paul J; Borges, Eric; Rueter, Bjoern; Heider, Karl-Heinz; Marcucci, Guido; Muthusamy, Natarajan

    2016-06-01

    Acute myeloid leukemia (AML) is the most common type of acute leukemia, affecting older individuals at a median age of 67 years. Resistance to intensive induction chemotherapy is the major cause of death in elderly AML; hence, novel treatment strategies are warranted. CD33-directed antibody-drug conjugates (gemtuzumab ozogamicin) have been shown to improve overall survival, validating CD33 as a target for antibody-based therapy of AML. Here, we report the in vitro efficacy of BI 836858, a fully human, Fc-engineered, anti-CD33 antibody using AML cell lines and primary AML blasts as targets. BI 836858-opsonized AML cells significantly induced both autologous and allogeneic natural killer (NK)-cell degranulation and NK-cell-mediated antibody-dependent cellular cytotoxicity (ADCC). In vitro treatment of AML blasts with decitabine (DAC) or 5-azacytidine, 2 hypomethylating agents that show efficacy in older patients, did not compromise BI 836858-induced NK-cell-mediated ADCC. Evaluation of BI 836858-mediated ADCC in serial marrow AML aspirates in patients who received a 10-day course of DAC (pre-DAC, days 4, 11, and 28 post-DAC) revealed significantly higher ADCC in samples at day 28 post-DAC when compared with pre-DAC treatment. Analysis of ligands to activating receptors (NKG2D) showed significantly increased NKG2D ligand [NKG2DL] expression in day 28 post-DAC samples compared with pre-DAC samples; when NKG2DL receptor was blocked using antibodies, BI 836858-mediated ADCC was significantly decreased, suggesting that DAC enhances AML blast susceptibility to BI 836858 by upregulating NKG2DL. These data provide a rationale for combination therapy of Fc-engineered antibodies such as BI 836858 with azanucleosides in elderly patients with AML. PMID:27013443

  4. Epitaxial growth of high mobility Bi{sub 2}Se{sub 3} thin films on CdS

    SciTech Connect

    Kou, X. F.; He, L.; Xiu, F. X.; Lang, M. R.; Yu, X. X.; Tang, J. S.; Huang, G.; Jiang, X. W.; Zhu, J. F.; Wang, K. L.; Liao, Z. M.; Zou, J.; Wang, Y.; Fedorov, A. V.

    2011-06-13

    We report the experiment of high quality epitaxial growth of Bi{sub 2}Se{sub 3} thin films on hexagonal CdS (0001) substrates using a solid source molecular-beam epitaxy system. Layer-by-layer growth of single crystal Bi{sub 2}Se{sub 3} has been observed from the first quintuple layer. The size of surface triangular terraces has exceeded 1 {mu}m. Angle-resolved photoemission spectroscopy clearly reveals the presence of Dirac-cone-shape surface states. Magneto-transport measurements demonstrate a high Hall mobility of {approx}6000 cm{sup 2}/V s for the as-grown Bi{sub 2}Se{sub 3} thin films at temperatures below 30 K. These characteristics of Bi{sub 2}Se{sub 3} thin films promise a variety of potential applications in ultrafast, low-power dissipation devices.

  5. In situ crystallization for fabrication of a core-satellite structured BiOBr-CdS heterostructure with excellent visible-light-responsive photoreactivity

    NASA Astrophysics Data System (ADS)

    Guo, Yuxi; Huang, Hongwei; He, Ying; Tian, Na; Zhang, Tierui; Chu, Paul K.; An, Qi; Zhang, Yihe

    2015-07-01

    We demonstrate the fabrication of a core-satellite structured BiOBr-CdS photocatalyst with highly efficient photocatalytic reactivity via a facile in situ crystallization approach at room temperature. The transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) results reveal that the BiOBr flakes are surrounded by CdS particles. The coverage of the satellites on the surface of the BiOBr nanosheets could be controlled by changing the content of the CdS, which contributes to the enhanced level of photocatalytic performance. The UV-vis diffuse reflection spectra demonstrate that the visible light absorption of the BiOBr-CdS photocatalyst is also enhanced by the CdS loaded. The excellent structural and spectral properties endow the BiOBr-CdS heterojunctions with improved photocatalytic performance pertaining to bisphenol A (BPA) degradation and photocurrent generation. Under visible light irradiation, the optimum photocatalytic activity of BiOBr-CdS at a molar ratio of 1 : 5 (CdS/BiOBr) is almost 2.8 times and 24.6 times as high as that of pure BiOBr and CdS. The remarkably enhanced photoreactivity should be attributed to the match in the energy levels and close core-satellite structural coupling between the CdS and BiOBr, which greatly facilitates the separation and transfer of photoinduced electron-hole pairs, as confirmed by photoluminescence (PL) and electrochemical impedance spectra (EIS). The present work sheds new light on the construction of highly efficient core-satellite heterojunctional photocatalysts for practical applications.We demonstrate the fabrication of a core-satellite structured BiOBr-CdS photocatalyst with highly efficient photocatalytic reactivity via a facile in situ crystallization approach at room temperature. The transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) results reveal that the BiOBr flakes are surrounded by CdS particles. The coverage of

  6. In situ crystallization for fabrication of a core-satellite structured BiOBr-CdS heterostructure with excellent visible-light-responsive photoreactivity.

    PubMed

    Guo, Yuxi; Huang, Hongwei; He, Ying; Tian, Na; Zhang, Tierui; Chu, Paul K; An, Qi; Zhang, Yihe

    2015-07-21

    We demonstrate the fabrication of a core-satellite structured BiOBr-CdS photocatalyst with highly efficient photocatalytic reactivity via a facile in situ crystallization approach at room temperature. The transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) results reveal that the BiOBr flakes are surrounded by CdS particles. The coverage of the satellites on the surface of the BiOBr nanosheets could be controlled by changing the content of the CdS, which contributes to the enhanced level of photocatalytic performance. The UV-vis diffuse reflection spectra demonstrate that the visible light absorption of the BiOBr-CdS photocatalyst is also enhanced by the CdS loaded. The excellent structural and spectral properties endow the BiOBr-CdS heterojunctions with improved photocatalytic performance pertaining to bisphenol A (BPA) degradation and photocurrent generation. Under visible light irradiation, the optimum photocatalytic activity of BiOBr-CdS at a molar ratio of 1 : 5 (CdS/BiOBr) is almost 2.8 times and 24.6 times as high as that of pure BiOBr and CdS. The remarkably enhanced photoreactivity should be attributed to the match in the energy levels and close core-satellite structural coupling between the CdS and BiOBr, which greatly facilitates the separation and transfer of photoinduced electron-hole pairs, as confirmed by photoluminescence (PL) and electrochemical impedance spectra (EIS). The present work sheds new light on the construction of highly efficient core-satellite heterojunctional photocatalysts for practical applications. PMID:26102357

  7. Hybrid Au-CdSe and Ag-CdSe nanoflowers and core-shell nanocrystals via one-pot heterogeneous nucleation and growth.

    PubMed

    AbouZeid, Khaled M; Mohamed, Mona B; El-Shall, M Samy

    2011-12-01

    A general approach, based on heterogeneous nucleation and growth of CdSe nanostructures on Au or Ag nanocrystals, for the synthesis of Au-CdSe and Ag-CdSe hybrid nanostructures is developed. The new approach provides a versatile one-pot route for the synthesis of hybrid nanoflowers consisting of a gold or silver core and multipod CdSe rods or an intact CdSe shell with controlled thickness, depending on the nucleation and growth parameters. At lower growth temperatures such as 150 °C, the CdSe clusters are adsorbed on the surface of the metal cores in their surface defects, then multiple arms and branches form, resulting in nanoflower-shaped hybrid structures. Increasing the size of the metal core through the choice of the reducing and capping agents results in an improvement of the interface between the metal and CdSe domains, producing core-shell structures. The growth temperature appears to be the most important factor determining the nature of the interface between the metal and CdSe domains. At relatively high temperatures such as 300 °C, the formation of large, faceted Au cores creates preferential growth sites for the CdSe nanocrystalline shell, thus resulting in well-defined Au-CdSe core-shell structures with large interfaces between the Au and CdSe domains. The present approach is expected to foster systematic studies of the electronic structures and optical properties of the metal-semiconductor hybrid materials for potential applications in photovoltaic and nanoelectronic devices. PMID:21994186

  8. Bi-SERS sensing and enhancement by Au-Ag bimetallic non-alloyed nanoparticles on amorphous and crystalline silicon substrate.

    PubMed

    Tan, Chee Leong; Lee, Soo Kyung; Lee, Yong Tak

    2015-03-01

    We have demonstrated Au-Ag bimetallic non-alloy nanoparticles (BNNPs) on thin a-Si film and c-Si substrate for high SERS enhancement, low cost, high sensitivity and reproducible SERS substrate with bi-SERS sensing properties where two different SERS peak for Au NPs and Ag NPs are observed on single SERS substrate. The isolated Au-Ag bimetallic NPs, with uniform size and spacing distribution, are suitable for uniform high density hotspot SERS enhancement. The SERS enhancement factor of Au-Ag BNNPs is 2.9 times higher compared to Ag NPs on similar substrates due to the increase of the localized surface plasmon resonance effect. However there is a decrement of SERS peak intensity at specific wavenumbers when the surrounding refractive index increases due to out-phase hybridization of Au NPs. The distinct changes of the two different SERS peaks on single Au-Ag BNNPs SERS substrate due to Au and Ag NPs independently show possible application for bi-molecular sensing. PMID:25836846

  9. A highly sensitive photoelectrochemical detection of perfluorooctanic acid with molecularly imprined polymer-functionalized nanoarchitectured hybrid of AgI-BiOI composite.

    PubMed

    Gong, Jingming; Fang, Tian; Peng, Dinghua; Li, Aimin; Zhang, Lizhi

    2015-11-15

    A rapid and ultrasensitive signal-off photoelectrochemical sensor has been developed under visible-light irradiation, for the detection of perfluorooctanoic acid (PFOA), especially low level PFOA present in environment, whereby a novel nanostructured probe made of molecularly imprinted polymer (MIP) modified AgI nanoparticles-BiOI nanoflake arrays (AgI-BiOINFs) is designed as the photoactive electrode (denoted as MIP@AgI-BiOINFs). Here, the unique nanoarchitectured hybrid of AgI-BiOINFs was first in situ synthesized via a facile successive ionic layer adsorption and reaction (SILAR) approach and then employed as a matrix to graft the recognition element of MIP. Such a newly designed PEC sensor exhibits high sensitivity and selectivity for the determination of PFOA. The PEC analysis is highly linear over the PFOA concentration ranging from 0.02 to 1000.0 ppb with a detection limit of 0.01 ppb (S/N=3). This value obtained by using the facile PEC sensor is comparable to the results obtained by using well-established liquid chromatography-tandem mass spectrometry (LC-MS/MS). Toward practical applications, this low-cost and sensitive assay was successfully applied to measure PFOA in real water samples. PMID:26092130

  10. Low-energy electron elastic scattering from Mn, Cu, Zn, Ni, Ag, and Cd atoms

    SciTech Connect

    Felfli, Z.; Msezane, A. Z.; Sokolovski, D.

    2011-05-15

    Electron elastic total cross sections (TCSs) for ground and excited Mn, Cu, Zn, Ni, Ag, and Cd atoms have been investigated in the electron-impact energy range 0 {<=}E{<=} 1 eV. The near-threshold TCSs for both the ground and excited states of these atoms are found to be characterized by Ramsauer-Townsend minima, shape resonances, and extremely sharp resonances corresponding to the formation of stable bound negative ions. The recently developed Regge-pole methodology where the crucial electron-electron correlations are embedded is employed for the calculations. From close scrutiny of the imaginary parts of the complex angular momenta, we conclude that these atoms form stable weakly bound ground and excited negative ions as Regge resonances through slow electron collisions. The extracted electron binding energies from the elastic TCSs of these atoms are contrasted with the available experimental and theoretical values.

  11. Metal arsonate polymers of Cd, Zn, Ag and Pb supported by 4-aminophenylarsonic acid

    SciTech Connect

    Lesikar-Parrish, Leslie A.; Neilson, Robert H.; Richards, Anne F.

    2013-02-15

    The coordination preferences of 4-aminophenylarsonic acid, 4-NH{sub 2}C{sub 6}H{sub 4}AsO{sub 3}H{sub 2}, (p-arsanilic acid) with CdCl{sub 2}{center_dot}2.5H{sub 2}O, ZnCl{sub 2}, Ag(SO{sub 3}CF{sub 3}) and Pb(NO{sub 3}){sub 2} have been investigated affording five new metal arsonate polymers. The reaction between 4-aminophenylarsonic acid and CdCl{sub 2}{center_dot}2.5H{sub 2}O resulted in a one-dimensional polymer, [{l_brace}Cd(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3}H)(Cl){sub 2}{r_brace}(H{sub 2}O){sub 2}]{sub n}, 1, in which the polymeric chain is propagated by bridging chlorides. Exchange of CdCl{sub 2} for ZnCl{sub 2} afforded [{l_brace}Zn{sub 2}(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3})(Cl){sub 2}{r_brace}(H{sub 2}O){sub 2}(Cl)]{sub n}, 2, featuring interlinked 6- and 8-membered [Zn-O-As] ring systems. The reaction of Ag(SO{sub 3}CF{sub 3}) with 4-aminophenylarsonic acid, afforded polymeric 3, [Ag(4-NH{sub 2}C{sub 6}H{sub 4}AsO{sub 3}H)(4-NH{sub 2}C{sub 6}H{sub 4}AsO{sub 3}H{sub 2})]{sub n} where coordination of the amino group to the silver center is observed and [{l_brace}Ag{sub 2}(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3}H)(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3})({mu}2-SO{sub 3}CF{sub 3}){sub 2}{r_brace}(SO{sub 3}CF{sub 3}){sub 2}]{sub n}, 4. By comparison, the reaction of p-arsanilic acid with Pb(NO{sub 3}){sub 2} yielded a polymeric chain [Pb(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3}H)(NO{sub 3}){sub 2}]{sub n}, 5 of similar topology to 1. The structures of 1-5 have been indiscriminately characterized by single crystal X-ray diffraction and their composition supported by relevant spectroscopic techniques. A comparison of the structural features of these polymers is used to determine the coordination preference of the ligand and factors influencing structural motifs, for example, the role of the anion. - Graphical abstract: The reaction of 4-aminophenylarsonic acid, 4-NH{sub 2}C{sub 6}H{sub 4}AsO{sub 3}H{sub 2}, with cadmium, zinc, silver, and lead have resulted in

  12. Photocatalytic activity of CdS and Ag2S quantum dots deposited on poly(amidoamine) functionalized carbon nanotubes

    PubMed Central

    Neelgund, Gururaj M.; Oki, Aderemi

    2011-01-01

    Two novel ternary nanocatalysts, f-MWCNTs-CdS and f-MWCNTs-Ag2S were successfully constructed by covalent grafting of fourth generation (G4) hyperbranched, crosslinked poly(amidoamine) (PAMAM) to carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) and subsequent deposition of CdS or Ag2S quantum dots (QDs). The structural transformation, surface potential, and morphology of functionalized MWCNTs (f-MWCNTs) and nanocatalysts were characterized by UV-vis spectrophotometer, Fourier transform infrared spectroscopy, powder X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, scanning electron microscopy and energy dispersive spectroscopy. Transmission electron microscopy reveals the effective anchoring of QDs on f-MWCNTs. The catalytic activity of nanocatalysts was evaluated by photodegradation of methyl orange under illumination of UV light. The coupling of MWCNTs, PAMAM and CdS or Ag2S QDs significantly enhanced the catalytic efficiency of nanocatalysts. The rate constants for degradation of methyl orange in presence of nanocatalysts were calculated using the Langmuir-Hinshelwood model. Overall, the excellence in photodegradation was accomplished by hybridizing f-MWCNTs with CdS or Ag2S PMID:22267895

  13. Effects of low-level Ag doping on Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}

    SciTech Connect

    Deis, T.A.; Eror, N.G.; Krishnaraj, P.; Prorok, B.C.; Lelovic, M.; Balachandran, U.

    1995-07-01

    Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} has been doped with silver, up to 10,000 ppm, in three ways: excess additions, substitution of Ag for Bi, and substitution of Ag for Sr. Effects of doping on the c-axis lattice parameter and critical temperature ({Tc}) were measured. Effects from doing were only observed in slow-cooled [10{degree}/hr] oxygen equilibrated samples. Doping by excess additions caused a small decrease in {Tc} and an increase in the c-axis length of the lattice. Doping by substitution, compared to excess Ag additions, caused a larger decrease in {Tc} and higher c-axis values for doping levels up to 1,000 ppm. Doping by substitution at higher levels (1,000--10,000 ppm) caused {Tc} to increase and the c-axis to decrease. Samples with similar substitutional doping levels exhibited comparable {Tc} values and samples with Ag substituted for Sr consistently exhibited higher c-axis values than samples that had equivalent amounts of Ag substituted for Bi.

  14. Synthesis and characterization of hierarchical multilayered flower-like assemblies of Ag doped Bi2WO6 and their photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Dumrongrojthanath, Phattharanit; Thongtem, Titipun; Phuruangrat, Anukorn; Thongtem, Somchai

    2013-12-01

    In this research, 0-3 mol% Ag doped Bi2WO6 hierarchical multilayered flower-like assemblies were successfully synthesized by a simple hydrothermal method at 180 °C for 24 h. The XRD, FE-SEM, FTIR and Raman analyses revealed the presence of flower-like Russellite Bi2WO6 structures which were constructed from a large number of orderly arranged 2D layers of interconnected nanoplates. Their photocatalytic activities were evaluated by photodegradation of rhodamine B (RhB) under Xe visible light irradiation (λ > 420 nm). The 3 mol% Ag doped Bi2WO6 showed the highest photocatalytic activities of 98.20% within 180 min.

  15. Photo-reduction of bromate in drinking water by metallic Ag and reduced graphene oxide (RGO) jointly modified BiVO4 under visible light irradiation.

    PubMed

    Chen, Fei; Yang, Qi; Zhong, Yu; An, Hongxue; Zhao, Jianwei; Xie, Ting; Xu, Qiuxiang; Li, Xiaoming; Wang, Dongbo; Zeng, Guangming

    2016-09-15

    Bromate (BrO3(-)), an oxyhalide disinfection by-product (DBP) in drinking water, has been demonstrated to be carcinogenic and genotoxic. In the current work, metallic Ag and reduced graphene oxide (RGO) co-modified BiVO4 was successfully synthesized by a stepwise chemical method coupling with a photo-deposition process and applied in the photo-reduction of BrO3(-) under visible light irradiation. In this composite, metallic Ag acted as an electron donor or mediator and RGO enhanced the BrO3(-) adsorption onto the surface of catalysts as well as an electron acceptor to restrict the recombination of photo-generated electron-hole pairs. The Ag@BiVO4@RGO composite exhibited greater photo-reduction BrO3(-) performance than pure BiVO4, Ag@BiVO4 and RGO@BiVO4 under identical experimental conditions: initial BrO3(-) concentration 150 μg/L, catalyst dosage 0.5 g/L, pH 7.0 and visible light (λ > 420 nm). The photoluminescence spectra (PL), electron-spin resonance (ESR), photocurrent density (PC) and electrochemical impedance spectroscopy (EIS) measurements indicated that the modified BiVO4 enhanced the photo-generated electrons and separated the electron-hole pairs. The photocatalytic reduction efficiency for BrO3(-) removal decreased with the addition of electron quencher K2S2O8, suggesting that electrons were the primary factor in this photo-reduction process. The declining photo-reduction efficiency of BrO3(-) in tap water should attribute to the consumption of photo-generated electrons by coexisting anions and the adsorption of dissolved organic matter (DOM) on graphene surface. The overall results indicate a promising application potential for photo-reduction in the DBPs removal from drinking water. PMID:27311108

  16. Synthesis and properties of new CdSe-AgI-As{sub 2}Se{sub 3} chalcogenide glasses

    SciTech Connect

    Kassem, M.; Le Coq, D.; Fourmentin, M.; Hindle, F.; Bokova, M.; Cuisset, A.; Masselin, P.; Bychkov, E.

    2011-02-15

    Research highlights: {yields} Determination of the glass-forming region in the pseudo-ternary CdSe-AgI-As{sub 2}Se{sub 3} system. {yields} Characterization of macroscopic properties of the new CdSe-AgI-As{sub 2}Se{sub 3} glasses. {yields} Far infrared transmission of chalcogenide glasses. {yields} Characterization of the total conductivity of CdSe-AgI-As{sub 2}Se{sub 3} glasses. -- Abstract: The glass-forming region in the pseudo-ternary CdSe-AgI-As{sub 2}Se{sub 3} system was determined. Measurements including differential scanning calorimetry (DSC), density, and X-ray diffraction were performed. The effect resulting from the addition of CdSe or AgI has been highlighted by examining three series of different base glasses. The characteristic temperatures of the glass samples, including glass transition (T{sub g}), crystallisation (T{sub x}), and melting (T{sub m}) temperatures are reported and used to calculate their {Delta}T = T{sub x} - T{sub g} and their Hruby, H{sub r} = (T{sub x} - T{sub g})/(T{sub m} - T{sub x}), criteria. Evolution of the total electrical conductivity {sigma} and the room temperature conductivity {sigma}{sub 298} was also studied. The terahertz transparency domain in the 50-600 cm{sup -1} region was pointed for different chalcogenide glasses (ChGs) and the potential of the THz spectroscopy was suggested to obtain structural information on ChGs.

  17. Synthesis, characterizations and anti-bacterial activities of pure and Ag doped CdO nanoparticles by chemical precipitation method

    NASA Astrophysics Data System (ADS)

    Sivakumar, S.; Venkatesan, A.; Soundhirarajan, P.; Khatiwada, Chandra Prasad

    2015-02-01

    In the present study, synthesized pure and Ag (1%, 2%, and 3%) doped Cadmium Oxide (CdO) nanoparticles by chemical precipitation method. Then, the synthesized products were characterized by thermo gravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectroscopy, Ultra violet-Vis diffused reflectance spectroscopy (UV-Vis-DRS), Scanning electron microscopy (SEM), Energy dispersive X-rays (EDX) spectroscopy, and anti-bacterial activities, respectively. The transition temperatures and phase transitions of Cd(OH)2 to CdO at 400 °C was confirmed by TG-DTA analysis. The XRD patterns show the cubic shape and average particle sizes are 21, 40, 34, and 37 nm, respectively for pure and Ag doped samples. FT-IR study confirmed the presence of CdO and Ag at 677 and 459 cm-1, respectively. UV-Vis-DRS study shows the variation on direct and indirect band gaps. The surface morphologies and elemental analysis have been confirmed from SEM and with EDX. In addition, the synthesized products have been characterized by antibacterial activities against Gram-positive and negative bacteria. Further, the present investigation suggests that CdO nanoparticles have the great potential applications on various industrial and medical fields of research.

  18. Frequency dependent electrical properties of nano-CdS/Ag junctions

    NASA Astrophysics Data System (ADS)

    Mohanta, D.; Choudhury, A.

    2005-05-01

    Polymer embedded cadmium sulfide nanoparticles/quantum dots were synthesized by a chemical route using polyvinyl alcohol (lmw) as the desired matrix. In an attempt to measure the electrical properties of nano-CdS/Ag samples, we propose that contribution from surface traps are mainly responsible in determining the I˜ V and C˜ V characteristics in high frequency ranges. To be specific, beyond 1.2 MHz, the carrier injection from the trap centers of the embedded quantum dots is ensured by large current establishment even at negative biasing condition of the junction. The unexpected nonlinear signature of C˜ V response is believed to be due to the fact that while trying to follow very high signal frequency (at least 10-3 of recombination frequency), there is complete abruptness in carrier trapping (charging) or/and detrapping (decay) in a given CdS nanoparticle assembly. The frequency dependent unique role of the trap carriers certainly find application in nanoelectronic devices at a desirable frequency of operation.

  19. Decorating CdTe QD-Embedded Mesoporous Silica Nanospheres with Ag NPs to Prevent Bacteria Invasion for Enhanced Anticounterfeit Applications.

    PubMed

    Gao, Yangyang; Dong, Qigeqi; Lan, Shi; Cai, Qian; Simalou, Oudjaniyobi; Zhang, Shiqi; Gao, Ge; Chokto, Harnoode; Dong, Alideertu

    2015-05-13

    Quantum dots (QDs) as potent candidates possess advantageous superiority in fluorescence imaging applications, but they are susceptible to the biological circumstances (e.g., bacterial environment), leading to fluorescence quenching or lose of fluorescent properties. In this work, CdTe QDs were embedded into mesoporous silica nanospheres (m-SiO2 NSs) for preventing QD agglomeration, and then CdTe QD-embedded m-SiO2 NSs (m-SiO2/CdTe NSs) were modified with Ag nanoparticles (Ag NPs) to prevent bacteria invasion for enhanced anticounterfeit applications. The m-SiO2 NSs, which serve as intermediate layers to combine CdTe QDs with Ag NPs, help us establish a highly fluorescent and long-term antibacterial system (i.e., m-SiO2/CdTe/Ag NSs). More importantly, CdTe QD-embedded m-SiO2 NSs showed fluorescence quenching when they encounter bacteria, which was avoided by attaching Ag NPs outside. Ag NPs are superior to CdTe QDs for preventing bacteria invasion because of the structure (well-dispersed Ag NPs), size (small diameter), and surface charge (positive zeta potentials) of Ag NPs. The plausible antibacterial mechanisms of m-SiO2/CdTe/Ag NSs toward both Gram-positive and Gram-negative bacteria were established. As for potential applications, m-SiO2/CdTe/Ag NSs were developed as fluorescent anticounterfeiting ink for enhanced imaging applications. PMID:25901940

  20. Influence of test methods on critical current degradation of Bi-2223/Ag superconductor tapes by bending strain

    NASA Astrophysics Data System (ADS)

    Kuroda, Tsuneo; Katagiri, Kazumune; Shin, Hyung-Seop; Itoh, Kikuo; Kumakura, Hiroaki; Wada, Hitoshi

    2005-12-01

    The results of two test methods were compared among three laboratories to determine a standard measurement method of critical current (Ic) as a function of bending strain for Ag-sheathed Bi-2223 superconductors. The VAMAS round-robin-test method (RRT) and the bending-rig method developed by Goldacker were used. The Ic degradation started with less bending strain for RRT than for bending-rig. Average irreversible strains (ɛirr) were 0.30% for RRT and 0.37% for bending-rig. Another test identified parameters that affected the results. A modified RRT method, with a current connection between the sample and the electrode, was used to avoid some thermal stresses of the test procedure. The ɛirr values increased to the level of the bending-rig, but the modified RRT Ic degradation rate with bending strain was higher. The stress states during sample bending differed between these methods. The shear stress was examined as a source of the Ic degradation rate differences with strain in terms of the crack propagation and delamination defects of oxide filaments from the Ag sheath.

  1. High critical current density Bi2Sr2CaCu2O x /Ag wire containing oxide precursor synthesized from nano-oxides

    NASA Astrophysics Data System (ADS)

    Zhang, Yun; Johnson, Stephen; Naderi, Golsa; Chaubal, Manasi; Hunt, Andrew; Schwartz, Justin

    2016-09-01

    Bi2Sr2CaCu2O x (Bi2212)/Ag-alloy wires are manufactured via the oxide-powder-in-tube route by filling Ag/Ag-alloy tubes with Bi2212 oxide precursor, deforming into wire, restacking and heat treating using partial-melt processing (PMP). Recent studies propose several requirements on precursor properties, including stoichiometry, chemical homogeneity, carbon content and phase purity. Here, nanosize oxides produced by nGimat’s proprietary NanoSpray CombustionTM process are used as starting materials to synthesize Bi2212 oxide precursors via solid-state calcination. Oxide powders for wire fill (precursor powder) with precisely controlled stoichiometry and chemical homogeneity containing over 99 vol% of single Bi2212-phase are synthesized. Alkaline-earth cuprate are found to be the only impurity phase in the precursor powders. Phase transformation, carbon release and grain growth during calcination are studied through a series of quench studies. Effects of particle size, surface area, stoichiometry, chemical homogeneity and microstructures of the starting materials on Bi2212 formation and wire transport properties are discussed. Small particle size, high surface area and short diffusion length of the starting materials result in a rapid and homogeneous phase transformation to Bi2212, along with an early and rapid carbon release. The residual carbon in the precursor powder is between 50 and 90 ppm. The strong dependence of transport J c on precursor stoichiometry indicates that compositional variations within precursor powders should be less than 1.5 mol%. Two Bi-rich and Ca-deficient stoichiometries give higher wire transport critical current density, with the highest being 2520 A mm‑2 (4.2 K, 5 T) after 1 bar PMP and 4560 A mm‑2 (4.2 K, 5 T) after 100 bar overpressure (OP) processing. The low residual carbon content results in smaller and fewer voids within an OP-processed wire filament. Bi-rich and Ca-deficient stoichiometries and small compositional variations

  2. The Broad Anti-AML Activity of the CD33/CD3 BiTE Antibody Construct, AMG 330, Is Impacted by Disease Stage and Risk

    PubMed Central

    Laszlo, George S.; Newhall, Kathryn J.; Sinclair, Angus M.; Frankel, Stanley R.; Kischel, Roman; Chen, Guang; Walter, Roland B.

    2015-01-01

    The CD33/CD3-bispecific T-cell engaging (BiTE) antibody construct, AMG 330, potently lyses CD33+ leukemic cells in vitro. Using specimens from 41 patients with acute myeloid leukemia (AML), we studied the factors that might contribute to clinical response or resistance. For this purpose, thawed aliquots of primary AML samples were immunophenotypically characterized and subjected to various doses of AMG 330 in the presence or absence of healthy donor T-cells. After 48 hours, drug-specific cytotoxicity was quantified and correlated with CD33 expression levels, amounts of T-cells present, and other disease characteristics. AMG 330 caused modest cytotoxicity that was correlated with the amount of autologous T-cells (P = 0.0001) but not CD33 expression, as AMG 330 exerted marked cytotoxic effects in several specimens with minimal CD33 expression. With healthy donor T-cells added, AMG 330 cytotoxicity depended on the drug dose and effector:target (E:T) cell ratio. High cytotoxic activity was observed even with minimal CD33 expression, and AMG 330 cytotoxicity and CD33 expression correlated only at high E:T cell ratio and high AMG 330 doses (P<0.003). AMG 330 resulted in significantly higher cytotoxicity in specimens from patients with newly diagnosed AML than those with relapsed/refractory disease despite similar levels of CD33 on myeloblasts. AMG 330 cytotoxicity also appeared greater in specimens from patients with favorable-risk disease as compared to other specimens. Together, our data demonstrate that AMG 330 is highly active in primary AML specimens across the entire disease spectrum, while suggesting the presence of yet undefined, CD33-independent, relative resistance mechanisms in specific patient subsets. PMID:26305211

  3. Recent Progress in High Performance Ag-Sheathed Bi2223 Wire (DI-BSCCO®)

    NASA Astrophysics Data System (ADS)

    Kagiyama, T.; Yamazaki, K.; Kikuchi, M.; Yamade, S.; Nakashima, T.; Kobayashi, S.; Hayashi, K.; Sato, K.; Shimoyama, J.; Inoue, M.; Higashikawa, K.; Kiss, T.; Kitaguchi, H.; Kumakura, H.

    2011-10-01

    Sumitomo Electric has been developing the silver-sheathed Bi2223 multi-filamentary wires since the discovery of Bi-based superconductors. DI-BSCCO is the high performance wires produced using the controlled-overpressure (CT-OP) sintering technique. The present commercial DI-BSCCO can provide the uniform high critical current, Ic, up to 180 A with length over 2000 m, and recently 200 A were succeeded to be obtained by the same kind of 1000 m length wires, resulting from the improvement and control of the microstructure in Bi2223 multi-filaments. The short trial wires of several meters have exhibited the highest Ic over 240 A at 77K in self-field (corresponding to 580 A per 1 cm-width). Besides, the optimization of carrier density after CT-OP led to further enhancement of Ic, reached 250 A. All the derivative products also have uniform critical current properties over entire length even after lamination with the reinforcing metals. The performances of DI-BSCCO can meet the growing needs for various application of high temperature superconductor like high in-field applications, such as magnets and motors. The recent progress in transport properties of commercial DI-BSCCO and R&D short trial wires is shown.

  4. Effect of axial strain on the critical current of Ag-sheathed Bi-based superconductors in magnetic fields up to 25 T

    SciTech Connect

    Ekin, J.W. ); Finnemore, D.K.; Li, Q. ); Tenbrink, J. ); Carter, W. )

    1992-08-17

    The irreversible strain limit {epsilon}{sub irrev} for the onset of permanent axial strain damage to Ag-sheathed Bi{sub 2}Sr{sub 2}Ca{sub 1}Cu{sub 2}O{sub 8+{ital x}} and Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10+{ital x}} superconductors has been measured to be in the range of 0.2%--0.35%. This strain damage onset is about an order of magnitude higher than for {ital bulk} {ital sintered} Y-, Bi-, or Tl-based superconductors and is approaching practical values for magnet design. The measurements show that the value of {epsilon}{sub irrev} is not dependent on magnetic field, nor does the critical current depend on strain below {epsilon}{sub irrev} at least up to 25 T at 4.2 K. Both of these factors indicate that the observed strain effect in Ag-sheathed Bi-based superconductors is not intrinsic to the superconductor material. Rather, the effect is extrinsic and arises from superconductor fracture. Thus, the damage onset is amenable to further enhancement. Indeed, the data suggest that subdividing the superconductor into fine filaments or adding Ag to the superconductor powder prior to processing significantly enhances the damage threshold {epsilon}{sub irrev} to above 0.6%.

  5. Targeted alpha-therapy using [Bi-213]anti-CD20 as novel treatment option for radio- and chemoresistant non-Hodgkin lymphoma cells

    PubMed Central

    Roscher, Mareike; Hormann, Inis; Leib, Oliver; Marx, Sebastian; Moreno, Josue; Miltner, Erich; Friesen, Claudia

    2013-01-01

    Radioimmunotherapy (RIT) is an emerging treatment option for non-Hodgkin lymphoma (NHL) producing higher overall response and complete remission rates compared with unlabelled antibodies. However, the majority of patients treated with conventional or myeloablative doses of radiolabelled antibodies relapse. The development of RIT with alpha-emitters is attractive for a variety of cancers because of the high linear energy transfer (LET) and short path length of alpha-radiation in human tissue, allowing higher tumour cell kill and lower toxicity to healthy tissues. In this study, we investigated the molecular effects of the alpha-emitter Bi-213 labelled to anti-CD20 antibodies ([Bi-213]anti-CD20) on cell cycle and cell death in sensitive and radio-/chemoresistant NHL cells. [Bi-213]anti-CD20 induced apoptosis, activated caspase-3, caspase-2 and caspase-9 and cleaved PARP specifically in CD20-expressing sensitive as well as in chemoresistant, beta-radiation resistant and gamma-radiation resistant NHL cells. CD20 negative cells were not affected by [Bi-213]anti-CD20 and unspecific antibodies labelled with Bi-213 could not kill NHL cells. Breaking radio-/chemoresistance in NHL cells using [Bi-213]anti-CD20 depends on caspase activation as demonstrated by complete inhibition of [Bi-213]anti-CD20-induced apoptosis with zVAD.fmk, a specific inhibitor of caspases activation. This suggests that deficient activation of caspases was reversed in radioresistant NHL cells using [Bi-213]anti-CD20. Activation of mitochondria, resulting in caspase-9 activation was restored and downregulation of Bcl-xL and XIAP, death-inhibiting proteins, was found after [Bi-213]anti-CD20 treatment in radio-/chemosensitive and radio-/chemoresistant NHL cells. [Bi-213]anti-CD20 seems to be a promising radioimmunoconjugate to improve therapeutic success by breaking radio- and chemoresistance selectively in CD20-expressing NHL cells via re-activating apoptotic pathways through reversing deficient

  6. Growth kinetics study of the (Bi,Pb) 2Sr 2Ca 2Cu 3O 10 grains in Ag/Ni composite-sheathed tapes

    NASA Astrophysics Data System (ADS)

    Chen, Xingpin; Yu, Xiaowei; Zhang, Jingpeng; Li, Mingya; Sun, Haibo; Liu, Qing

    2011-12-01

    The growth kinetics of the (Bi,Pb) 2Sr 2Ca 2Cu 3O 10 (Bi-2223) grains in Ag/Ni sheathed tapes have been investigated by the means of XRD and SEM. Samples were sintered at 837 °C for various time under low oxygen partial pressure. Monofilament tape after sintered for 50 h has a critical current ( I c) of 3.6 A. An analysis of the Bi-2223 phase evolution using Avrami relation reveals a three-stage process with obvious changes of the n-exponent during the Bi-2223 formation after about 3 and 20 h sintering. Secondary electron images show that the Bi-2223 grains nucleate at the initial stage and grow within a-b plane until their edges impinge each other. The thicknesses of Bi-2223 grains are measured statistically after various sintering time. The data denote that the thickness increase with the extension of sintering time and become more rapidly after 10 h sintering. A detailed process describing the growth of Bi-2223 grains is presented basing on the n-exponent and microstructural observation.

  7. Distributions of dissolved trace metals (Cd, Cu, Mn, Pb, Ag) in the southeastern Atlantic and the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Boye, M.; Wake, B. D.; Lopez Garcia, P.; Bown, J.; Baker, A. R.; Achterberg, E. P.

    2012-08-01

    Comprehensive synoptic datasets (surface water down to 4000 m) of dissolved cadmium (Cd), copper (Cu), manganese (Mn), lead (Pb) and silver (Ag) are presented along a section between 34° S and 57° S in the southeastern Atlantic Ocean and the Southern Ocean to the south off South Africa. The vertical distributions of Cu and Ag display nutrient-like profiles similar to silicic acid, and of Cd similar to phosphate. The distribution of Mn shows a subsurface maximum in the oxygen minimum zone, whereas Pb concentrations are rather invariable with depth. Dry deposition of aerosols is thought to be an important source of Pb to surface waters close to South Africa, and dry deposition and snowfall may have been significant sources of Cu and Mn at the higher latitudes. Furthermore, the advection of water masses enriched in trace metals following contact with continental margins appeared to be an important source of trace elements to the surface, intermediate and deep waters in the southeastern Atlantic Ocean and the Antarctic Circumpolar Current. Hydrothermal inputs may have formed a source of trace metals to the deep waters over the Bouvet Triple Junction ridge crest, as suggested by relatively enhanced dissolved Mn concentrations. The biological utilization of Cu and Ag was proportional to that of silicic acid across the section, suggesting that diatoms formed an important control over the removal of Cu and Ag from surface waters. However, uptake by dino- and nano-flagellates may have influenced the distribution of Cu and Ag in the surface waters of the subtropical Atlantic domain. Cadmium correlated strongly with phosphate (P), yielding lower Cd / P ratios in the subtropical surface waters where phosphate concentrations were below 0.95 μM. The greater depletion of Cd relative to P observed in the Weddell Gyre compared to the Antarctic Circumpolar Current could be due to increase Cd uptake induced by iron-limiting conditions in these high-nutrient-low-chlorophyll waters

  8. Distributions of dissolved trace metals (Cd, Cu, Mn, Pb, Ag) in the southeastern Atlantic and the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Boye, M.; Wake, B. D.; Lopez Garcia, P.; Bown, J.; Baker, A. R.; Achterberg, E. P.

    2012-03-01

    Comprehensive synoptic datasets (surface water down to 4000 m) of dissolved cadmium (Cd), copper (Cu), manganese (Mn), lead (Pb) and silver (Ag) are presented along a section between 34° S and 57° S in the southeastern Atlantic Ocean and the Southern Ocean to the south off South Africa. The vertical distributions of Cu, Ag, and of Cd display nutrient-like profiles similar to silicic acid, and phosphate, respectively. The distribution of Mn shows a subsurface maximum in the oxygen minimum zone, whereas Pb concentrations are rather invariable with depth. Dry deposition of aerosols is thought to be an important source of Pb to surface waters close to South Africa, and dry deposition and snowfall may have been significant sources of Cu and Mn at the higher latitudes. Furthermore, the advection of water-masses enriched in trace metals following contact with continental margins appeared to be an important source of trace elements to the surface, intermediate and deep waters in the southeastern Atlantic Ocean and the Antarctic Circumpolar Current. Hydrothermal inputs appeared to have formed a source of trace metals to the deep waters over the Bouvet Triple Junction ridge crest, as suggested by relatively enhanced dissolved Mn concentrations. The biological utilization of Cu and Ag was proportional to that of silicic acid across the section, suggesting that diatoms formed an important control over the removal of Cu and Ag from surface waters. However uptake by dino- and nano-flagelattes may have influenced the distribution of Cu and Ag in the surface waters of the subtropical Atlantic domain. Cadmium correlated strongly with phosphate (P), yielding lower Cd/P ratios in the subtropical surface waters where phosphate concentrations were below 0.95 μM. The greater depletion of Cd relative to P observed in the Weddell Gyre compared to the Antarctic Circumpolar Current could be due to increase Cd-uptake induced by iron-limiting conditions in these High-Nutrient Low

  9. Time evolution of phase composition and microstructure in the Ag/Bi-2223 composite superconductor heat-treated at specific pO2/temperature set points

    NASA Astrophysics Data System (ADS)

    Baurceanu, R. M.; Maroni, V. A.; Merchant, N. N.; Fischer, A. K.; McNallan, M. J.; Parrella, R. D.

    2002-07-01

    The time evolution of the phases present in the ceramic cores of silver-sheathed (Bi, Pb)2Sr2Ca2Cu3Ox (Ag/Bi-2223) multifilament superconducting tapes heat-treated at selected oxygen partial pressure/temperature (pO2/T) set points was investigated using scanning electron microscopy and energy dispersive spectroscopy coupled with computer-based image processing methods. The numerical values for individual phase contents and non-superconducting second phase (NSP) size distributions generated in this way were used to quantify the temporal evolution of composition in the variably treated Ag/Bi-2223 tapes. Results for the three pO2/T set points investigated (21.0% O2/835 °C, 7.5% O2/825 °C and 4.0% O2/815 °C) revealed characteristic patterns of recurring maxima and minima in the time evolution of the NSPs. (Ca, Sr)14Cu24O41 was found to be the stable phase at 21.0% O2/835 °C, possibly evolving as a co-product of the Bi-2223 formation reaction, while (Ca, Sr)2CuO3 and CuO were stable at 4.0% O2/815 °C, presumably as a consequence of competitive secondary reactions proceeding in parallel with Bi-2223 formation. The best-aligned grains were formed in Ag/Bi-2223 tapes treated at 21.0% O2/835 °C, while the best conversion to Bi-2223, together with the least amount of NSP particles >0.5 μm in major dimension, was produced by the 7.5% O2/825 °C treatment. A forward-looking conclusion of the study is that it appears possible to minimize the amount and size of NSP particles during Ag/Bi-2223 heat treatment by using a combinatorial sequence of appropriately timed pO2/T set points.

  10. Particulate contacts to Si and CdTe: Al, Ag, Hg-Cu-Te, and Sb-Te

    NASA Astrophysics Data System (ADS)

    Schulz, Douglas L.; Ribelin, Rosine; Curtis, Calvin J.; Ginley, David S.

    1999-03-01

    Our team has been investigating the use of particle-based contacts in both Si and CdTe solar cell technologies. First, in the area of contacts to Si, powders of Al and Ag prepared by an electroexplosion process have been characterized by transmission electron microscopy (TEM), TEM elemental determination X-ray spectroscopy (TEM-EDS), and TEM electron diffraction (TEM-ED). These Al and Ag particles were slurried and tested as contacts to p- and n-type silicon wafers, respectively. Linear current-voltage (I-V) was observed for Ag on n-type Si, indicative of an ohmic contact, whereas the Al on p-type Si sample was non-ideal. A wet-chemical surface treatment was performed on one Al sample and TEM-EDS indicated a substantial decrease in the O contaminant level. The treated Al on p-type Si films exhibited linear I-V after annealing. Second, in the area of contacts to CdTe, particles of Hg-Cu-Te and Sb-Te have been applied as contacts to CdTe/CdS/SnO2 heterostructures prepared by the standard NREL protocol. First, Hg-Cu-Te and Sb-Te were prepared by a metathesis reaction. After CdCl2 treatment and NP etch of the CdTe layer, particle contacts were applied. The Hg-Cu-Te contacted cells exhibited good electrical characteristics, with Voc>810 mV and efficiencies > 11.5% for most cells. Although Voc>800 mV were observed for the Sb-Te contacted cells, efficiencies in these devices were limited to 9.1% presumably by a large series resistance (>20 Ω) observed in all samples.

  11. Efficient visible-light photocatalytic activity by band alignment in mesoporous ternary polyoxometalate-Ag2S-CdS semiconductors

    NASA Astrophysics Data System (ADS)

    Kornarakis, I.; Lykakis, I. N.; Vordos, N.; Armatas, G. S.

    2014-07-01

    Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster anions with different reduction potentials, such as PW12O403-, SiW12O404- and PMo12O403-, were employed as electron acceptors in these ternary heterojunction photocatalysts. Characterization by small-angle X-ray scattering, X-ray diffraction, transmission electron microscopy and N2 physisorption measurements showed hexagonal arrays of POM-Ag2S-CdS hybrid nanorods with large internal BET surface areas and uniform mesopores. The Keggin structure of the incorporated POM clusters was also verified by elemental X-ray spectroscopy microanalysis, infrared and diffuse-reflectance ultraviolet-visible spectroscopy. These new porous materials were implemented as visible-light-driven photocatalysts, displaying exceptional high activity in aerobic oxidation of various para-substituted benzyl alcohols to the corresponding carbonyl compounds. Our experiments show that the spatial separation of photogenerated electrons and holes at CdS through the potential gradient along the CdS-Ag2S-POM interfaces is responsible for the increased photocatalytic activity.Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster

  12. Testing WHAM-FTOX with laboratory toxicity data for mixtures of metals (Cu, Zn, Cd, Ag, Pb).

    PubMed

    Tipping, Edward; Lofts, Stephen

    2015-04-01

    The Windermere humic aqueous model using the toxicity function (WHAM-FTOX ) describes cation toxicity to aquatic organisms in terms of 1) accumulation by the organism of metabolically active protons and metals at reversible binding sites, and 2) differing toxic potencies of the bound cations. Cation accumulation (νi , in mol g(-1) ) is estimated through calculations with the WHAM chemical speciation model by assuming that organism binding sites can be represented by those of humic acid. Toxicity coefficients (αi ) are combined with νi to obtain the variable FTOX (= Σ αi νi ) which, between lower and upper thresholds (FTOX,LT , FTOX,UT ), is linearly related to toxic effect. Values of αi , FTOX,LT , and FTOX,LT are obtained by fitting toxicity data. Reasonable fits (72% of variance in toxic effect explained overall) were obtained for 4 large metal mixture acute toxicity experiments involving daphnids (Cu, Zn, Cd), lettuce (Cu, Zn, Ag), and trout (Zn, Cd, Pb). Strong nonadditive effects, most apparent in results for tests involving Cd, could be explained approximately by purely chemical competition for metal accumulation. Tentative interpretation of parameter values obtained from these and other experimental data suggests the following order of bound cation toxicity: H < Al < (Cu Zn Pb UO2 ) < (Cd Ag). Another trend is a strong increase in Cd toxicity relative to that of Zn as organism complexity increases (from bacteria to fish). PMID:25318827

  13. CD209 (DC-SIGN) -336A>G promoter polymorphism and severe acute respiratory syndrome in Hong Kong Chinese.

    PubMed

    Chan, Kelvin Yuen Kwong; Xu, Mei-Shu; Ching, Johannes Chi Yun; So, Thomas Man Kit; Lai, Sik-To; Chu, Chung-Ming; Yam, Loretta Y C; Wong, Andrew T Y; Chung, Pui Hong; Chan, Vera Sau Fong; Lin, Chen Lung Steve; Sham, Pak Chung; Leung, Gabriel M; Peiris, Joseph S M; Khoo, Ui-Soon

    2010-07-01

    CD209 (DC-SIGN) is an important C-type lectin which acts a receptor of many pathogens. The single nucleotide polymorphism (SNP) -336A>G in the CD209 promoter has been demonstrated to regulate promoter activity and to be associated with several important infectious diseases, such as human immunodeficiency virus-1 (HIV-1), Mycobacterium tuberculosis, and Dengue fever. CD209 facilitates severe acute respiratory syndrome (SARS)-coronavirus spike protein-bearing pseudotype driven infection of permissive cells in vitro. In keeping with previously published findings, our in vitro studies confirmed that this SNP modulates gene promoter activity. Genetic association analysis of this SNP with clinico-pathologic outcomes in 824 serologic confirmed SARS patients showed that the -336AG/GG genotype SARS patients was associated with lower standardized lactate-dehydrogenase (LDH) levels compared with the -336AA patients (p = 0.014, odds ratio = 0.40). High LDH levels are known to be an independent predictor for poor clinical outcome, probably related to tissue destruction from immune hyperactivity. Hence, SARS patients with the CD209 -336 AA genotype carry a 60% chance of having a poorer prognosis. This association is in keeping with the role of CD209 in modulating immune response to viral infection. The relevance of these findings for other infectious diseases and inflammatory conditions would be worth investigating. PMID:20359516

  14. Bioleaching mechanism of Zn, Pb, In, Ag, Cd and As from Pb/Zn smelting slag by autotrophic bacteria.

    PubMed

    Wang, Jia; Huang, Qifei; Li, Ting; Xin, Baoping; Chen, Shi; Guo, Xingming; Liu, Changhao; Li, Yuping

    2015-08-15

    A few studies have focused on release of valuable/toxic metals from Pb/Zn smelting slag by heterotrophic bioleaching using expensive yeast extract as an energy source. The high leaching cost greatly limits the practical potential of the method. In this work, autotrophic bioleaching using cheap sulfur or/and pyrite as energy matter was firstly applied to tackle the smelting slag and the bioleaching mechanisms were explained. The results indicated autotrophic bioleaching can solubilize valuable/toxic metals from slag, yielding maximum extraction efficiencies of 90% for Zn, 86% for Cd and 71% for In, although the extraction efficiencies of Pb, As and Ag were poor. The bioleaching performance of Zn, Cd and Pb was independent of leaching system, and leaching mechanism was acid dissolution. A maximum efficiency of 25% for As was achieved by acid dissolution in sulfursulfur oxidizing bacteria (S-SOB), but the formation of FeAsO4 reduced extraction efficiency in mixed energy source - mixed culture (MS-MC). Combined works of acid dissolution and Fe(3+) oxidation in MS-MC was responsible for the highest extraction efficiency of 71% for In. Ag was present in the slag as refractory AgPb4(AsO4)3 and AgFe2S3, so extraction did not occur. PMID:25996622

  15. Effects of morphology, diameter and periodic distance of the Ag nanoparticle periodic arrays on the enhancement of the plasmonic field absorption in the CdSe quantum dots

    NASA Astrophysics Data System (ADS)

    Kohnehpoushi, Saman; Eskandari, Mehdi; Ahmadi, Vahid; Yousefirad, Mansooreh; Nabavi, Elham

    2016-09-01

    In this work, the numerical calculations of plasmonic field absorption of Ag nanoparticles (Ag NPs) periodic arrays in the CdSe quantum dot (QD) film are investigated by the three-dimensional finite difference time domain (FDTD). Diameter (D), periodic distance (P), and morphology effects of Ag NPs are investigated on the improvement of the plasmonic field absorption in CdSe QD film. Results show that plasmonic field absorption in CdSe QD film is enhanced with reduction of D of Ag NPs until 5 nm and reduces thereafter. It is observed that with raising D of Ag NPs, optimum plasmonic field absorption in CdSe QD film is shifted toward the higher P. Moreover, with varying morphology of Ag NPs from spherical to cylindrical, cubic, ringing and pyramid, the plasmonic field absorption is considerably enhanced in CdSe QD film and position of quadrupole plasmon mode (QPPM) is shifted toward further wavelength. For cylindrical Ag NPs, the QPPM intensity increased with raising height (H) until 15 nm and reduces thereafter.

  16. Plasmonic enhancement of the optical absorption and catalytic efficiency of BiVO₄ photoanodes decorated with Ag@SiO₂ core-shell nanoparticles.

    PubMed

    Abdi, Fatwa F; Dabirian, Ali; Dam, Bernard; van de Krol, Roel

    2014-08-01

    Recent progress in the development of bismuth vanadate (BiVO4) photoanodes has firmly established it as a promising material for solar water splitting applications. Performance limitations due to intrinsically poor catalytic activity and slow electron transport have been successfully addressed through the application of water oxidation co-catalysts and novel doping strategies. The next bottleneck to tackle is the modest optical absorption in BiVO4, particularly close to its absorption edge of 2.4 eV. Here, we explore the modification of the BiVO4 surface with Ag@SiO2 core-shell plasmonic nanoparticles. A photocurrent enhancement by a factor of ~2.5 is found under 1 sun illumination (AM1.5). We show that this enhancement consists of two contributions: optical absorption and catalysis. The optical absorption enhancement is induced by the excitation of localized surface plasmon resonances in the Ag nanoparticles, and agrees well with our full-field electromagnetic simulations. Far-field effects (scattering) are found to be dominant, with a smaller contribution from near-field plasmonic enhancement. In addition, a significant catalytic enhancement is observed, which is tentatively attributed to the electrocatalytic activity of the Ag@SiO2 nanoparticles. PMID:24942363

  17. Synthesis, characterization and evaluation of the photocatalytic performance of Ag-CdMoO{sub 4} solar light driven plasmonic photocatalyst

    SciTech Connect

    Adhikari, Rajesh; Malla, Shova; Gyawali, Gobinda; Sekino, Tohru; Lee, Soo Wohn

    2013-09-01

    Graphical abstract: - Highlights: • Ag-CdMoO{sub 4} solar light driven photocatalyst was successfully synthesized. • Photocatalyst exhibited strong absorption in the visible region. • Photocatalytic activity was significantly enhanced. • Enhanced activity was caused by the SPR effect induced by Ag nanoparticles. - Abstract: Ag-CdMoO{sub 4} plasmonic photocatalyst was synthesized in ethanol/water mixture by photo assisted co-precipitation method at room temperature. As synthesized powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyzer. Photocatalytic activity was evaluated by performing the degradation experiment over methylene blue (MB) and indigo carmine (IC) as model dyes under simulated solar light irradiation. The results revealed that the Ag-CdMoO{sub 4} showed the higher photocatalytic performance as compared to CdMoO{sub 4} nanoparticles. Dispersion of Ag nanoparticles over the surface of CdMoO{sub 4} nanoparticles causes the surface plasmon resonance (SPR) and enhances the broad absorption in the entire visible region of the solar spectrum. Hence, dispersion of Ag nanoparticles over CdMoO{sub 4} nanoparticles could be the better alternative to enhance the absorption of visible light by scheelite crystal family for effective photocatalysis.

  18. Effect of oxygen partial pressure on superconducting properties of Bi-2212/Ag tapes prepared by doctor-blade method

    SciTech Connect

    Inoue, N.; Okada, M.; Higashiyama, K.

    1997-06-01

    The authors have investigated the relationship between oxygen partial pressure (P{sub O{sub 2}}) during the partial-melting process and superconducting properties for doctor-blade processed Bi-2212/Ag tapes. Tapes were heat-treated at various P{sub O{sub 2}} value of 0.01-1.00 atm. The DTA results for the doctor-blade tapes showed the melting point of the oxide rose with increasing P{sub O{sub 2}}. Correspondingly, the optimum heat-treatment temperature also increased with increasing P{sub O{sub 2}}. The tapes at P{sub O{sub 2}}=1.00 atm had the highest J{sub c} values of over 10{sup 5} A/cm{sup 2} at conditions of 4.2K, 10T, and their a.c. susceptibility showed a sharp transition indicating improved intergrain coupling. Examination of cross sections for tapes melted above 0.20atm PO{sub 2} showed the good crystal alignment. From these results, it was concluded that processing at high PO{sub 2} was an effective method to obtain good superconducting properties for doctor-blade tapes.

  19. Magnetic properties and irreversibility behavior in Ag-sheathed Bi-based superconducting wires fabricated using a controlled melt procedure

    SciTech Connect

    Dou, S.X.; Liu, H.K.; Guo, Y.C.; Shi, D.L.; Sumption, M.D.; Collings, E.W.

    1992-12-01

    A significant enhancement of the in-field J{sub c} of Ag-clad (Bi,Pb)-Sr-Ca-Cu-0 (BPSCCO:2223) wires has been achieved using a controlled melt procedure. The greatly reduced weak linking has resulted in an extended plateau regime in the J{sub c}-H curve. J{sub c}s of 40,000 A/cm{sup 2} at 77 K (self field) and 9,000 A/cm{sup 2} at 77 K (1 T) have been achieved. The improved J. H characteristics may be attributed to microstructures consisting of uniform grain alignment throughout the entire cross section, intimate connection between grains, impurities within the grains, and an optimal level of dispersed 2212 phase. Irreversibility line measurements using both AC susceptibility in DC fields (reported elsewhere), and magnetization measurements, have indicated that flux pinning can be enhanced in the melt-processed samples over the results of normal solid-state processing with its less-than optimal 2212-phase content. But sufficiently long annealing times during the ``normal`` route may achieve 2212-phase content and J{sub c}s which are comparable to those of melt-processed samples.

  20. Magnetic properties and irreversibility behavior in Ag-sheathed Bi-based superconducting wires fabricated using a controlled melt procedure

    SciTech Connect

    Dou, S.X.; Liu, H.K.; Guo, Y.C. . School of Materials Science and Engineering); Shi, D.L. ); Sumption, M.D.; Collings, E.W. )

    1992-12-01

    A significant enhancement of the in-field J[sub c] of Ag-clad (Bi,Pb)-Sr-Ca-Cu-0 (BPSCCO:2223) wires has been achieved using a controlled melt procedure. The greatly reduced weak linking has resulted in an extended plateau regime in the J[sub c]-H curve. J[sub c]s of 40,000 A/cm[sup 2] at 77 K (self field) and 9,000 A/cm[sup 2] at 77 K (1 T) have been achieved. The improved J. H characteristics may be attributed to microstructures consisting of uniform grain alignment throughout the entire cross section, intimate connection between grains, impurities within the grains, and an optimal level of dispersed 2212 phase. Irreversibility line measurements using both AC susceptibility in DC fields (reported elsewhere), and magnetization measurements, have indicated that flux pinning can be enhanced in the melt-processed samples over the results of normal solid-state processing with its less-than optimal 2212-phase content. But sufficiently long annealing times during the normal'' route may achieve 2212-phase content and J[sub c]s which are comparable to those of melt-processed samples.

  1. Ultrahigh mobility and giant magnetoresistance in the Dirac Semimetals Cd3As2 and Na3Bi

    NASA Astrophysics Data System (ADS)

    Ong, N. Phuan

    2015-03-01

    Dirac semimetals and Weyl semimetals are 3D analogs of graphene in which crystalline symmetry protects the nodes against gap formation. Na3Bi and Cd3As2 were predicted to be Dirac semimetals, and recently confirmed to be so by photoemission. Several novel transport properties in a magnetic field H have been proposed for Dirac semimetals. Here we report an interesting property in Cd3As2 that was unpredicted, namely a remarkable protection mechanism that strongly suppresses back-scattering in zero H. In single crystals, the protection results in a very high mobility, 107 cm2/Vs at 5 K. Suppression of backscattering results in a transport lifetime 104longer than the quantum lifetime. The lifting of this protection by H leads to very large magnetoresistance with a striking H-linear profile. I will also report transport results on Na3Bi and compare them with results in Cd3As2. I discuss how this may relate to changes to the Fermi surface induced by H. Research supported by the Army Research Office (W911NF-11-1-0379), MURI grant (ARO W911NF-12-1-0461) and NSF (DMR 0819860).

  2. Structural features of AgCaCdMg{sub 2}(PO{sub 4}){sub 3} and AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, two new compounds with the alluaudite-type structure, and their catalytic activity in butan-2-ol conversion

    SciTech Connect

    Kacimi, Mohammed; Ziyad, Mahfoud; Hatert, Frederic . E-mail: fhatert@ulg.ac.be

    2005-04-20

    AgCaCdMg{sub 2}(PO{sub 4}){sub 3} and AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, two new compounds with the alluaudite-type structure, were synthesized by a solid state reaction in air at 750 deg. C. The X-ray powder diffraction pattern of AgCaCdMg{sub 2}(PO{sub 4}){sub 3} indicates the presence of small amounts of (Ca, Mg){sub 3}(PO{sub 4}){sub 2} with the whitlockite structure, as impurity, whereas AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3} is constituted by pure alluaudite. The Rietveld refinements of the X-ray powder diffraction patterns indicate an ordered cationic distribution for AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}, with Ag on A(2)', Cd on A(1) and M(1), and Mg on M(2), whereas a disordered distribution of Cd and Ca between the A(1) and M(1) sites is observed for AgCaCdMg{sub 2}(PO{sub 4}){sub 3}. The catalytic properties of these compounds has been measured in reaction of butan-2-ol dehydrogenation. In the absence of oxygen, both samples exhibit poor dehydrogenation activity. All samples displayed no dehydration activity. Introduction of oxygen into the feed changed totally the catalytic behavior of the catalysts. The production of methyl ethyl ketone increases with time on stream and the reaction temperature. AgCaCdMg{sub 2}(PO{sub 4}){sub 3} is more efficient than AgCd{sub 2}Mg{sub 2}(PO{sub 4}){sub 3}.

  3. Protection associated with a TB vaccine is linked to increased frequency of Ag85A-specific CD4(+) T cells but no increase in avidity for Ag85A.

    PubMed

    Metcalfe, Hannah J; Steinbach, Sabine; Jones, Gareth J; Connelley, Tim; Morrison, W Ivan; Vordermeier, Martin; Villarreal-Ramos, Bernardo

    2016-08-31

    There is a need to improve the efficacy of Bacille Calmette-Guérin (BCG) vaccination against tuberculosis in humans and cattle. Previously, we found boosting BCG-primed cows with recombinant human type 5 adenovirus expressing antigen 85A (Ad5-85A) increased protection against Mycobacterium bovis infection compared to BCG vaccination alone. The aim of this study was to decipher aspects of the immune response associated with this enhanced protection. We compared BCG-primed Ad5-85A-boosted cattle with BCG-vaccinated cattle. Polyclonal CD4(+) T cell libraries were generated from pre-boost and post-boost peripheral blood mononuclear cells - using a method adapted from Geiger et al. (2009) - and screened for antigen 85A (Ag85A) specificity. Ag85A-specific CD4(+) T cell lines were analysed for their avidity for Ag85A and their Ag85A epitope specificity was defined. Boosting BCG with Ad5-85A increased the frequencies of post-boost Ag85A-specific CD4(+) T cells which correlated with protection (reduced pathology). Boosting Ag85A-specific CD4(+) T cell responses did not increase their avidity. The epitope specificity was variable between animals and we found no clear evidence for a post-boost epitope spreading. In conclusion, the protection associated with boosting BCG with Ad5-85A is linked with increased frequencies of Ag85A-specific CD4(+) T cells without increasing avidity or widening of the Ag85A-specific CD4(+) T cell repertoire. PMID:27498622

  4. Bi-functional CD22 ligands use multimeric immunoglobulins as protein scaffolds in assembly of immune complexes on B cells

    PubMed Central

    O'Reilly, Mary K.; Collins, Brian E.; Han, Shoufa; Liao, Liang; Rillahan, Cory; Kitov, Pavel I.; Bundle, David R.; Paulson, James C.

    2008-01-01

    CD22 is a B cell specific sialic-acid-binding immunoglobulin-like lectin (Siglec) whose function as a regulator of B cell signaling is modulated by its interaction with glycan ligands bearing the sequence NeuAcα2-6Gal. To date, only highly multivalent polymeric ligands (n=450) have achieved sufficient avidity to bind to CD22 on native B cells. Here we demonstrate that a synthetic bi-functional molecule comprising a ligand of CD22 linked to an antigen (nitrophenol; NP) can use a monoclonal anti-NP-IgM as a decavalent protein scaffold to efficiently drive assembly of IgM-CD22 complexes on the surface of native B cells. Surprisingly, anti-NP antibodies of lower valency, IgA (n =4) and IgG (n =2), were also found to drive complex formation, though with lower avidity. Ligands bearing alternate linkers of variable length and structure were constructed to establish the importance of a minimal length requirement, and versatility in the structural requirement. We show that the ligand drives assembly of IgM complexes exclusively on the surface of B cells and not other classes of white blood cells that do not express CD22, which lends itself to the possibility of targeting B cells in certain hematopoietic malignancies. PMID:18505252

  5. Ag plasmonic nanostructures and a novel gel electrolyte in a high efficiency TiO2/CdS solar cell.

    PubMed

    Kumar, P Naresh; Deepa, Melepurath; Srivastava, Avanish Kumar

    2015-04-21

    A novel photoanode architecture with plasmonic silver (Ag) nanostructures embedded in titania (TiO2), which served as the wide band gap semiconducting support and CdS quantum dots (QDs), as light absorbers, is presented. Ag nanostructures were prepared by a polyol method and are comprised of clumps of nanorods, 15-35 nm wide, interspersed with globular nanoparticles and they were characterized by a face centered cubic lattice. Optimization of Ag nanostructures was achieved on the basis of a superior power conversion efficiency (PCE) obtained for the cell with a Ag/TiO2/CdS electrode encompassing a mixed morphology of Ag nano-rods and particles, relative to analogous cells with either Ag nanoparticles or Ag nanorods. Interfacial charge transfer kinetics was unraveled by fluorescence quenching and lifetime studies. Ag nanostructures improve the light harvesting ability of the TiO2/CdS photoanode via (a) plasmonic and scattering effects, which induce both near- and far-field enhancements which translate to higher photocurrent densities and (b) charging effects, whereby, photoexcited electron transfer from TiO2 to Ag is facilitated by Fermi level equilibration. Owing to the spectacular ability of Ag nanostructures to increase light absorption, a greatly increased PCE of 4.27% and a maximum external quantum efficiency of 55% (at 440 nm) was achieved for the cell based on Ag/TiO2/CdS, greater by 42 and 66%, respectively, compared to the TiO2/CdS based cell. In addition, the liquid S(2-) electrolyte was replaced by a S(2-) gel containing fumed silica, and the redox potential, conductivity and p-type conduction of the two were deduced to be comparable. Although the gel based cells showed diminished solar cell performances compared to their liquid counterparts, nonetheless, the Ag/TiO2/CdS electrode continued to outperform the TiO2/CdS electrode. Our studies demonstrate that Ag nanostructures effectively capture a significant chunk of the electromagnetic spectrum and aid QD

  6. Effect of adherent bacteria and bacterial extracellular polymers upon assimilation by Macoma balthica of sediment-bound Cd, Zn and Ag

    USGS Publications Warehouse

    Harvey, Ronald W.; Luoma, Samuel N.

    1985-01-01

    Effects of adherent bacteria and bacterial extracellular polymer (exopolymer) upon uptake of particle-bound Cd, Zn and Ag by the deposit-feeding clam Macoma balthica were studied in the laboratory. Amorphous iron oxyhydroxide and unaltered and alkaline-extracted sediments were used as model particulates in separate, controlled deposit-feeding experiments. In general, amounts of metal taken up from ingested particles varied dramatically with the nature of the particle surface. Ingestion of contaminated iron oxide particles did not contribute to overall uptake of Cd and Ag in feeding clams, but accounted for 89 to 99% of total Zn uptake. Exopolymer adsorbed on iron oxide particles caused an increase in the biological availability of particle-bound metals in the order Ag>Cd>Zn, whereas adherent bacteria up to 3.2 X 1011 g-1 had no effect upon amounts of metal taken up from ingested particulates. At the higher Cd and Ag concentrations employed (3.6 X 10-7M), feeding rates declined with increasing amounts of iron oxide-bound exopolymer, suggesting behavioral avoidance due to increased metal availability. Much of the Cd (57 %) taken up by clams feeding on unaltered estuarine sediments originated from particulates, even though particle/solute distribution of Cd (86%) was similar to that in experiments with iron oxide particles. Uptake of Cd from alkalineextracted sediments was insignificant, as it was from unamended iron oxide. However, addition of exopolymer (10 mgg-1 sediment) caused a restoration nn bioavailability of sediment-bound Cd.

  7. Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures.

    PubMed

    Park, Jung Tae; Chi, Won Seok; Jeon, Harim; Kim, Jong Hak

    2014-03-01

    TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (η) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of η is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements. PMID:24457831

  8. Hall effect anomaly and low-temperature metamagnetism in the Kondo compound CeAgBi2

    NASA Astrophysics Data System (ADS)

    Thomas, S. M.; Rosa, P. F. S.; Lee, S. B.; Parameswaran, S. A.; Fisk, Z.; Xia, J.

    2016-02-01

    Heavy fermion (HF) materials exhibit a rich array of phenomena due to the strong Kondo coupling between their localized moments and itinerant electrons. A central question in their study is to understand the interplay between magnetic order and charge transport, and its role in stabilizing new quantum phases of matter. Particularly promising in this regard is a family of tetragonal intermetallic compounds Ce T X2 (where T denotes transition metal and X denotes pnictogen), which includes a variety of HF compounds showing T -linear electronic specific heat Ce˜γ T , with γ ˜20 -500 mJ mol-1K-2 , reflecting an effective-mass enhancement ranging from small to modest. Here, we study the low-temperature field-tuned phase diagram of high-quality CeAgBi2 using magnetometry and transport measurements. We find an antiferromagnetic transition at TN=6.4 K with weak magnetic anisotropy and the easy axis along the c axis, similar to previous reports (TN=6.1 K ). This scenario, along with the presence of two anisotropic Ruderman-Kittel-Kasuya-Yosida interactions, leads to a rich field-tuned magnetic phase diagram, consisting of five metamagnetic transitions of both first and second order. In addition, we unveil an anomalous Hall contribution for fields H <54 kOe , which is drastically altered when H is tuned through a trio of transitions at 57, 78, and 84 kOe, suggesting that the Fermi surface is reconstructed in a subset of the metamagnetic transitions.

  9. Metal-Silicate Partitioning of Bi, In, and Cd as a Function of Temperature and Melt Composition

    NASA Technical Reports Server (NTRS)

    Marin, Nicole; Righter, K.; Danielson, L.; Pando, K.; Lee, C.

    2013-01-01

    The origin of volatile elements in the Earth, Moon and Mars is not known; however, several theories have been proposed based on volatile elements such as In, As, Se, Te and Zn which are in lower concentration in the Earth, Moon, and Mars than in chondrites. Explanations for these low concentrations are based on two contrasting theories for the origin of Earth: equilibrium core formation versus late accretion. One idea is that the volatiles were added during growth of the planets and Moon, and some mobilized into the metallic core while others stayed in the mantle (e.g., [1]). The competing idea is that they were added to the mantles after core formation had completed (e.g., [2]). Testing these ideas involves quantitative modeling which can only be performed after data is obtained on the systematic metal-silicate partitioning behavior of volatile elements with temperature, pressure and melt composition. Until now, such data for Bi, In, and Cd has been lacking. After conducting a series of high pressure, high temperature experiments, the metal-silicate partition coefficients of Bi, In, and Cd as a function of temperature and melt composition can be used to evaluate potential conditions under which terrestrial planets differentiated into core and mantle, and how they acquired volatiles.

  10. Highly-sensitive organophosphorus pesticide biosensors based on CdTe quantum dots and bi-enzyme immobilized eggshell membranes.

    PubMed

    Xue, Gao; Yue, Zhao; Bing, Zhang; Yiwei, Tang; Xiuying, Liu; Jianrong, Li

    2016-02-01

    An optical biosensing method using CdTe quantum dots (QDs) and bi-enzyme-immobilized eggshell membranes for the determination of organophosphorus pesticides (OPs) has been developed. Increasing amounts of OPs led to a decrease of the enzymatic activity and thus a decrease in the production of hydrogen peroxide (H2O2), which can quench the fluorescence of the CdTe QDs. Under the optimum conditions, there was a good linear relationship between the enzyme inhibition percentage and the logarithm of paraoxon or parathion concentration in the range of 1.0 × 10(-11)-1.0 × 10(-6) mol L(-1). The detection limit (S/N = 3) of the proposed biosensors were as low as 4.30 × 10(-12) mol L(-1) for paraoxon and 2.47 × 10(-12) mol L(-1) for parathion. The bi-enzyme-immobilized eggshell membrane demonstrated a long shelf-life of at least 2 months and the results showed good repeatability. The proposed method was successfully applied to the determination of the OPs in real fruit samples with satisfactory results. PMID:26688862

  11. Distribution and determination of Pb, Cd, Bi and Cu in the sea brine system: solution--colloidal particles--biota.

    PubMed

    Bozhkov, Ognyan; Tzvetkova, Christina; Russeva, Elena

    2006-01-01

    The distribution of Pb, Cd, Bi, and Cu in Black Sea brine system (solution--colloidal particles--biota) produced in Burgas and Pomorie salterns is studied. The established distribution of the title elements among the brine components is as follows: Pb--25% in the salt solution, 30%--in colloidal particles, 45%--in biota (Halobacterium salinarium and microalgae Dunaliela salina); Cu--30% in the salt solution, 22%--in colloidal particles, 48%--in biota. Cd and Bi are not detected in biota. They are uniformly distributed (50%: 50%) between the salt solution and colloidal particles. Two procedures for analysis are developed. The first one is designed for determination of the total content of the studied metals in brine. It involves elimination of the biota interference by addition of ethanol, extraction and pre-concentration of the metals with NaDDC into CCl4 followed by FAAS determination. The second procedure intends determination of the elements in the separate components of the brine. It involves separation of the colloidal particles through centrifugation, separation of the studied elements from the resulting solution as dithiocarbamate complexes on a Millipore filter, dissolution of the retained metal species and subsequent FAAS analysis. PMID:16948432

  12. The effect of post-annealing on the critical current recovery of bending-deformed (Bi,Pb)-2223/Ag tapes

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Xie, L.; Li, P.; Qu, T.-M.; Song, Y.; Wang, X.-C.; Han, Z.

    2007-10-01

    (Bi,Pb)-2223/Ag tape fabricated by PIT methods is a promising candidate for electrical power application. In these applications, the tape often undergoes a winding process, which leads to the degradation of the critical current. In this paper, we report the effect of post-annealing on the critical current (Ic) recovery of bent-deformed (Bi,Pb)-2223/Ag multi-filamentary tapes. The tapes were bent at room temperature with different curvatures, then straightened and post-annealed with different processing parameters, including post-annealing temperature, dwelling time and oxygen partial pressure. The experiment results show that rather high Ic value could be obtained by post-annealing even for the tapes whose bending strain was 0.8%. SEM observation shows that the decreasing in Ic value is caused by the formation and propagation of transverse micro-cracks in the (Bi,Pb)-2223 filaments and the effect of post-annealing could be related to the healing of micro-cracks caused by bending strain as well as the improving of grain connectivity.

  13. Electronic Properties of MoSi2-Type Hf2X Intermetallic Compounds (X=Pd, Ag, Cd)

    NASA Astrophysics Data System (ADS)

    Yaar, I.; Maytal-Beck, S.; Berant, Z.

    2001-11-01

    The Hf z coordinate and the value of the electric field gradient (efg) main component (V zz ), were calculated for three Hf2X compounds (X = Pd, Ag, Cd) on a first-principle basis, using the full potential linear augmented plane wave (LAPW) method. Exchange and correlation effects were treated either by the local spine density approximation (LSDA) or by the more advanced generalized gradient approximation (GGA). The calculated V zz values, in the Hf site, were in very good agreement with available 181Hf TDPAC experimental results.

  14. CdS-Nanowires Flexible Photo-detector with Ag-Nanowires Electrode Based on Non-transfer Process

    PubMed Central

    Pei, Yanli; Pei, Ruihan; Liang, Xiaoci; Wang, Yuhao; Liu, Ling; Chen, Haibiao; Liang, Jun

    2016-01-01

    In this study, UV-visible flexible resistivity-type photo-detectors were demonstrated with CdS-nanowires (NWs) percolation network channel and Ag-NWs percolation network electrode. The devices were fabricated on Mixed Cellulose Esters (MCE) membrane using a lithographic filtration method combined with a facile non-transfer process. The photo-detectors demonstrated strong adhesion, fast response time, fast decay time, and high photo sensitivity. The high performance could be attributed to the high quality single crystalline CdS-NWs, encapsulation of NWs in MCE matrix and excellent interconnection of the NWs. Furthermore, the sensing performance was maintained even the device was bent at an angle of 90°. This research may pave the way for the facile fabrication of flexible photo-detectors with high performances. PMID:26899726

  15. CdS-Nanowires Flexible Photo-detector with Ag-Nanowires Electrode Based on Non-transfer Process

    NASA Astrophysics Data System (ADS)

    Pei, Yanli; Pei, Ruihan; Liang, Xiaoci; Wang, Yuhao; Liu, Ling; Chen, Haibiao; Liang, Jun

    2016-02-01

    In this study, UV-visible flexible resistivity-type photo-detectors were demonstrated with CdS-nanowires (NWs) percolation network channel and Ag-NWs percolation network electrode. The devices were fabricated on Mixed Cellulose Esters (MCE) membrane using a lithographic filtration method combined with a facile non-transfer process. The photo-detectors demonstrated strong adhesion, fast response time, fast decay time, and high photo sensitivity. The high performance could be attributed to the high quality single crystalline CdS-NWs, encapsulation of NWs in MCE matrix and excellent interconnection of the NWs. Furthermore, the sensing performance was maintained even the device was bent at an angle of 90°. This research may pave the way for the facile fabrication of flexible photo-detectors with high performances.

  16. CdS-Nanowires Flexible Photo-detector with Ag-Nanowires Electrode Based on Non-transfer Process.

    PubMed

    Pei, Yanli; Pei, Ruihan; Liang, Xiaoci; Wang, Yuhao; Liu, Ling; Chen, Haibiao; Liang, Jun

    2016-01-01

    In this study, UV-visible flexible resistivity-type photo-detectors were demonstrated with CdS-nanowires (NWs) percolation network channel and Ag-NWs percolation network electrode. The devices were fabricated on Mixed Cellulose Esters (MCE) membrane using a lithographic filtration method combined with a facile non-transfer process. The photo-detectors demonstrated strong adhesion, fast response time, fast decay time, and high photo sensitivity. The high performance could be attributed to the high quality single crystalline CdS-NWs, encapsulation of NWs in MCE matrix and excellent interconnection of the NWs. Furthermore, the sensing performance was maintained even the device was bent at an angle of 90°. This research may pave the way for the facile fabrication of flexible photo-detectors with high performances. PMID:26899726

  17. Bright white-light emission from Ag/SiO2/CdS-ZnS core/shell/shell plasmon couplers.

    PubMed

    Liao, Chen; Tang, Luping; Gao, Xiaoqin; Xu, Ruilin; Zhang, Huichao; Yu, Yongya; Lu, Changgui; Cui, Yiping; Zhang, Jiayu

    2015-12-28

    Well-defined plasmon couplers (PCs) that comprise a Ag core overcoated with a SiO(2) shell with controlled thickness, followed by a monolayer of CdS-ZnS core-shell quantum dots (QDs) were synthesized to modify the emission from trap-rich CdS-ZnS QDs by adjusting the distance between the QDs and Ag nanoparticles (NPs). When the thickness of the SiO(2) shell was 10 nm, because the shell could effectively suppress the non-radiative energy transfer from the semiconductor QDs to the metal NPs and the localized surface plasmon resonance (LSPR) of the Ag NPs spectrally matched the emission peak of the CdS-ZnS QDs to bring about strong plasmon coupling, optimum enhancements of the surface state emission (SSE) (17 times) and band-edge emission (BEE) (4 times) were simultaneously realized and the SSE to BEE intensity ratio was increased to 55%. As a result, a bright white-light source with 1931 Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.34) was realized by the superposition of the two emissions. The experimental results from Ag/SiO(2)/CdSe-ZnS and the Ag/SiO(2)/CdS:Mn-ZnS core/shell/shell PCs indicated that suppressing the non-radiative decay rate (k(nr)) was the underlying mechanism for plasmon coupling fluorescence enhancement. PMID:26592756

  18. Bright white-light emission from Ag/SiO2/CdS-ZnS core/shell/shell plasmon couplers

    NASA Astrophysics Data System (ADS)

    Liao, Chen; Tang, Luping; Gao, Xiaoqin; Xu, Ruilin; Zhang, Huichao; Yu, Yongya; Lu, Changgui; Cui, Yiping; Zhang, Jiayu

    2015-12-01

    Well-defined plasmon couplers (PCs) that comprise a Ag core overcoated with a SiO2 shell with controlled thickness, followed by a monolayer of CdS-ZnS core-shell quantum dots (QDs) were synthesized to modify the emission from trap-rich CdS-ZnS QDs by adjusting the distance between the QDs and Ag nanoparticles (NPs). When the thickness of the SiO2 shell was 10 nm, because the shell could effectively suppress the non-radiative energy transfer from the semiconductor QDs to the metal NPs and the localized surface plasmon resonance (LSPR) of the Ag NPs spectrally matched the emission peak of the CdS-ZnS QDs to bring about strong plasmon coupling, optimum enhancements of the surface state emission (SSE) (17 times) and band-edge emission (BEE) (4 times) were simultaneously realized and the SSE to BEE intensity ratio was increased to 55%. As a result, a bright white-light source with 1931 Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.34) was realized by the superposition of the two emissions. The experimental results from Ag/SiO2/CdSe-ZnS and the Ag/SiO2/CdS:Mn-ZnS core/shell/shell PCs indicated that suppressing the non-radiative decay rate (knr) was the underlying mechanism for plasmon coupling fluorescence enhancement.

  19. Modeling of the bending strain dependence of the critical current in Bi2223/Ag composite tapes based on the damage stress of the superconducting filament

    NASA Astrophysics Data System (ADS)

    Gou, Xiaofan; Shen, Qiang

    2012-05-01

    An analysis model of the bending strain dependence of the critical current in multifilamentary Bi2223/Ag composite tapes is presented. To investigate the effect of the mechanical properties of the Bi2223 superconducting filament, the actual part for carrying current, its damage stress and elastic modulus are introduced. The calculated result of the variation of the critical current with the bending strain is well agreed with the experimental one. The further studies find that the mechanical properties of the filament have a remarkable effect on the bending strain dependence of the critical current. Specifically, the larger the damage stress and elastic modulus of the filament are, the higher the critical current is, when the bending strain increases to a larger value beyond the critical one.

  20. A mechanism for resistive dissipation in Ag sheathed Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} and Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}

    SciTech Connect

    Suenaga, M.; Li, Q.; Sabatini, R.L.; Shibutani, K.; Hayoashi, S.; Ogawa, R.; Kawate, Y.; Motowidlo, L.

    1993-11-01

    Detailed measurements of the V-I curves for a number of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} and Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}/Ag composite tapes were made at 4.2, 27, and 64-77 K as a function of applied magnetic field as well as the angle between the tape face and the direction of applied field. Results suggest that the weak vortex-pinning strength, and the amount of the weakly coupled grain boundaries and of the non-superconducting volume are primary limiting factors for critical current densities in Bi(2212)/Ag and Bi(2223)/Ag, respectively. Furthermore, in both cases, the dissipative voltages arise from the interior of the gains.

  1. Chemically twinned phases in the Ag 2S-PbS-Bi 2S 3 system.Part I. Electron microscope study

    NASA Astrophysics Data System (ADS)

    Skowron, A.; Tilley, R. J. D.

    1990-04-01

    Phases in the PbS-rich region of the Ag 2S-PbS-Bi 2S 3 system have been studied by high resolution transmission electron microscopy. In samples quenched from the melt or melted and annealed at 773 or 973 K a number of new chemically twinned phases have been found. Their structures contain galena-like slabs four-, five-, seven-, and eight-octahedra wide, joined along twin planes. Ordered phases predominate in the PbS-rich region of the phase diagram, while both ordered and disordered intergrowths occur in the PbS-poor region. The role of Ag in stabilizing slabs of galena-like material five- and eight-octahedra wide and its function in the formation of these twinned phases is discussed.

  2. Thermomechanical processing of Ag-clad Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} superconductors

    SciTech Connect

    Wu, C.T.; Goretta, K.C.; Lanagan, M.T.; Biondo, A.C.; Poeppel, R.B.

    1993-10-01

    Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (2212) powders were synthesized by solid-state reaction, loaded into Ag tubes, and processed into tapes by various combinations of drawing, rolling, and heat treatment. Critical current densities at 4.2 K of greater than 10{sup 5} A/cm{sup 2} were achieved from microstructures consisting of large, highly textured 2212 grains. Optimal microstructures were produced by specific mechanical-working conditions and heat-treatment schedules that incorporated solid-state and partial-melt sintering. The relationships between processing, microstructure, and critical current density will be discussed.

  3. Static quadrupole moments of 106Agm and 109Agm and the electric field gradient of Ag in Zn and Cd

    NASA Astrophysics Data System (ADS)

    Berkes, I.; Hlimi, B.; Marest, G.; Sayouty, E. H.; Coussement, R.; Hardeman, F.; Put, P.; Scheveneels, G.

    1984-12-01

    Low temperature nuclear orientation of 106Agm and 110Agm in Zn and Fe and level mixing resonances on 109Agm have been measured in order to deduce Q and Vzz values. A fourth-order resonance in 109AgmZn has been found with a full width at half maximum of 1.9 × 10-9 eV, and Vzz(AgCd)Vzz(AgZn)=1.0064(34) was deduced. The electric quadrupole moments found in the literature, reevaluated for Sternheimer correction Q(108Agm)=+1.32(7) b and Q(110Agm)=+1.44(10) b, are used for the calibration of Vzz and yield Q(106Agm)=+1.11(11) b, Q(109Agm)=(+)0.97(11) b, and Vzz(AgZn)=+4.2(5)×1017 V/cm2. Furthermore, μ(106Agm)=(+)3.82(8)μN and several δ(E 2M 1) mixing ratios in 106Pd are also determined. The quadrupole moments are in good agreement with Yukawa-plus-exponential macroscopic model and folded-Yukawa microscopic model calculations. The particle states can be described in terms of deformed Nilsson orbitals or three valence-proton holes coupled to a quadrupole vibrator.

  4. Primary Effusion Lymphoma Cell Death Induced by Bortezomib and AG 490 Activates Dendritic Cells through CD91

    PubMed Central

    Cirone, Mara; Di Renzo, Livia; Lotti, Lavinia Vittoria; Conte, Valeria; Trivedi, Pankaj; Santarelli, Roberta; Gonnella, Roberta; Frati, Luigi; Faggioni, Alberto

    2012-01-01

    To understand how cytotoxic agent-induced cancer cell death affects the immune system is of fundamental importance to stimulate immune response to counteract the high mortality due to cancer. Here we compared the immunogenicity of Primary Effusion Lymphoma (PEL) cell death induced by anticancer drug Bortezomib (Velcade) and Tyrphostin AG 490, a Janus Activated Kinase 2/signal trasducer and activator of transcription-3 (JAK2/STAT3) inhibitor. We show that both treatments were able to induce PEL apoptosis with similar kinetics and promote dendritic cells (DC) maturation. The surface expression of molecules involved in immune activation, namely calreticulin (CRT), heat shock proteins (HSP) 90 and 70 increased in dying cells. This was correlated with DC activation. We found that PEL cell death induced by Bortezomib was more effective in inducing uptake by DC compared to AG 490 or combination of both drugs. However the DC activation induced by all treatments was completely inhibited when these cells were pretreated with a neutralizing antiboby directed against the HSP90/70 and CRT common receptor, CD91. The activation of DC by Bortezomib and AG 490 treated PEL cells, as seen in the present study, might have important implications for a combined chemo and immunotherapy in such patients. PMID:22412839

  5. Characteristic difference between ITO/ZrCu and ITO/Ag bi-layer films as transparent electrodes deposited on PET substrate

    NASA Astrophysics Data System (ADS)

    Lee, C. J.; Lin, H. K.; Sun, S. Y.; Huang, J. C.

    2010-10-01

    The metallic-glass film of ZrCu layer deposited by co-sputtering was utilized as the metallic layer in the bi-layer structure transparent conductive electrode of ITO/ZrCu (IZC) deposited on the PET substrate using magnetron sputtering at room temperature. In addition, the pure Ag metal layer was applied in the same structure of transparent conductive film, ITO/Ag, in comparison with the IZC film. The ZrCu layer could form a continuous and smooth film in thickness lower than 6 nm, compared with the island structure of pure Ag layer of the same thickness. The 30 nm ITO/3 nm ZrCu films could show the optical transmittance of 73% at 550 nm wavelength. The 30 nm ITO/12 nm ZrCu films could show the better sheet resistance of 20 Ω/sq, but it was still worse than that of the ITO/Ag films. It was suggested that an alloy system with lower resistivity and negative mixing heat between atoms might be another way to form a continuous layer in thickness lower than 6 nm for metal film.

  6. Microstructural evolution of a lead-free solder alloy Sn-Bi-Ag-Cu prepared by mechanical alloying during thermal shock and aging

    NASA Astrophysics Data System (ADS)

    Huang, M. L.; Wu, C. M. L.; Lai, J. K. L.; Chan, Y. C.

    2000-08-01

    In a previous study, a lead-free solder, Sn-6Bi-2Ag-0.5Cu, was developed by mechanical alloying. The alloy shows great potential as a lead-free solder system. In the present work, the microstructural evolution during thermal shock and aging was examined. In the as-soldered joints small bismuth (1 µm to 2 µm) and Ag3Sn (1 µm) particles were finely dispersed in a nearly pure tin matrix with a small amount of η-Cu6Sn5 phase in the bulk of solder. During thermal shock and aging microstructural evolution occurred with Cu-Sn intermetallic compound (IMC) layer growth at interface, bismuth phase coarsening and Ag3Sn phase coarsening. The microstructure of the solder appeared to be stable at high temperature. The shear strength of the present solder joint is higher than that of Sn-37Pb and Sn-3.5Ag solders. Shear failure occurred Cu-Sn IMC layer-solder interface and in the bulk of solder.

  7. High-Performance Fully Nanostructured Photodetector with Single-Crystalline CdS Nanotubes as Active Layer and Very Long Ag Nanowires as Transparent Electrodes.

    PubMed

    An, Qinwei; Meng, Xianquan; Sun, Pan

    2015-10-21

    Long and single-crystalline CdS nanotubes (NTs) have been prepared via a physical evaporation process. A metal-semiconductor-metal full-nanostructured photodetector with CdS NTs as active layer and Ag nanowires (NWs) of low resistivity and high transmissivity as electrodes has been fabricated and characterized. The CdS NTs-based photodetectors exhibit high performance, such as lowest dark currents (0.19 nA) and high photoresponse ratio (Ilight/Idark ≈ 4016) (among CdS nanostructure network photodetectors and NTs netwok photodetectors reported so far) and very low operation voltages (0.5 V). The photoconduction mechanism, including the formation of a Schottky barrier at the interface of Ag NW and CdS NTs and the effect of oxygen adsorption process on the Schottky barrier has also been provided in detail based on the studies of CdS NTs photodetector in air and vacuum. Furthermore, CdS NTs photodetector exhibits an enhanced photosensitivity as compared with CdS NWs photodetector. The enhancement in performance is dependent on the larger surface area of NTs adsorbing more oxygen in air and the microcavity structure of NTs with higher light absorption efficiency and external quantum efficiency. It is believed that CdS NTs can potentially be useful in the designs of 1D CdS-based optoelectronic devices and solar cells. PMID:26457660

  8. AGS67E, an Anti-CD37 Monomethyl Auristatin E Antibody–Drug Conjugate as a Potential Therapeutic for B/T-Cell Malignancies and AML: A New Role for CD37 in AML

    PubMed Central

    Pereira, Daniel S.; Guevara, Claudia I.; Jin, Liqing; Mbong, Nathan; Verlinsky, Alla; Hsu, Ssucheng J.; Aviña, Hector; Karki, Sher; Abad, Joseph D.; Yang, Peng; Moon, Sung-Ju; Malik, Faisal; Choi, Michael Y.; An, Zili; Morrison, Kendall; Challita-Eid, Pia M.; Doñate, Fernando; Joseph, Ingrid B.J.; Kipps, Thomas J.; Dick, John E.; Stover, David R.

    2015-01-01

    CD37 is a tetraspanin expressed on malignant B cells. Recently, CD37 has gained interest as a therapeutic target. We developed AGS67E, an antibody–drug conjugate that targets CD37 for the potential treatment of B/T-cell malignancies. It is a fully human monoclonal IgG2 antibody (AGS67C) conjugated, via a protease-cleavable linker, to the microtubule-disrupting agent mono-methyl auristatin E (MMAE). AGS67E induces potent cytotoxicity, apoptosis, and cell-cycle alterations in many non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL) cell lines and patient-derived samples in vitro. It also shows potent antitumor activity in NHL and CLL xenografts, including Rituxan-refractory models. During profiling studies to confirm the reported expression of CD37 in normal tissues and B-cell malignancies, we made the novel discovery that the CD37 protein was expressed in T-cell lymphomas and in AML. AGS67E bound to >80% of NHL and T-cell lymphomas, 100% of CLL and 100% of AML patient-derived samples, including CD34+CD38− leukemic stem cells. It also induced cytotoxicity, apoptosis, and cell-cycle alterations in AML cell lines and antitumor efficacy in orthotopic AML xenografts. Taken together, this study shows not only that AGS67E may serve as a potential therapeutic for B/T-cell malignancies, but it also demonstrates, for the first time, that CD37 is well expressed and a potential drug target in AML. PMID:25934707

  9. Ag nanoclusters could efficiently quench the photoresponse of CdS quantum dots for novel energy transfer-based photoelectrochemical bioanalysis.

    PubMed

    Zhang, Ling; Sun, Yue; Liang, Yan-Yu; He, Jian-Ping; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-11-15

    Herein the influence of ultrasmall Ag nanoclusters (Ag NCs) against CdS quantum dots (QDs) in a photoelectrochemical (PEC) nanosystem was exploited for the first time, based on which a novel PEC bioanalysis was successfully developed via the efficient quenching effect of Ag NCs against the CdS QDs. In a model system, DNA assay was achieved by using molecular beacon (MB) probes anchored on a CdS QDs modified electrode, and the MB probes contain two segments that can hybridize with both target DNA sequence and the label of DNA encapsulated Ag NCs. After the MB probe was unfolded by the target DNA sequence, the labels of oligonucleotide encapsulated Ag NCs would be brought in close proximity to the CdS QDs electrode surface, and efficient photocurrent quenching of QDs could be resulted from an energy transfer process that originated from NCs. Thus, by monitoring the attenuation in the photocurrent signal, an elegant and sensitive PEC DNA bioanalysis could be accomplished. The developed biosensor displayed a linear range from 1.0pM to 10nM and the detection limit was experimentally found to be of 0.3pM. This work presents a feasible signaling principle that could act as a common basis for general PEC bioanalysis development. PMID:27315518

  10. Bioconcentration of Ag, Cd, Co, Mn and Zn in the Mangrove Oyster (Crassostrea gasar) and Preliminary Human Health Risk Assessment: A Radiotracer Study.

    PubMed

    Kuranchie-Mensah, Harriet; Teyssié, Jean-Louis; Oberhänsli, François; Tumnoi, Yutthana; Pouil, Simon; Warnau, Michel; Metian, Marc

    2016-09-01

    Bioaccumulation kinetics of five dissolved metals were determined in the mangrove oyster Crassostrea gasar, using corresponding radiotracers ((54)Mn, (57)Co, (65)Zn, (109)Cd and (110m)Ag). Additionally, their bioaccessibility to human consumers was estimated. Results indicated that over a 14-day exposure (54)Mn and (57)Co were linearly concentrated in oysters whereas (109)Cd, (65)Zn and (110m)Ag were starting to saturate (steady-state not reached). Whole-body concentration factors at 14 days (CF14d in toto) ranged from 187 ± 65 to 629 ± 179 with the lowest bioconcentration capacity for Co and the highest for Ag. Depuration kinetics were best described by a double-exponential model with associated biological half-lives ranging from 26 days (Ag) to almost 8 months (Zn and Cd). Bioaccessible fraction of the studied elements was estimated using in vitro digestions, which suggested that oysters consumed seasoned with lemon enhanced the accessibility of Cd, Mn and Zn to human consumers, but not Ag and Co. PMID:27194421

  11. Plasmon enhanced CdS-quantum dot sensitized solar cell using ZnO nanorods array deposited with Ag nanoparticles as photoanode

    NASA Astrophysics Data System (ADS)

    Eskandari, M.; Ahmadi, V.; Yousefi rad, M.; Kohnehpoushi, S.

    2015-04-01

    CdS-quantum dot sensitized solar cell using ZnO nanorods (ZnO NRs) array deposited with Ag nanoparticles (Ag NPs) as photoanode was fabricated. Light absorption effect of Ag NPs on improvement of the cell performance was investigated. Performance improvement of metal nanoparticles (MNPs) was controlled by the structure design and architecture. Different decorations and densities of Ag NPs were utilized on the photoanode. Results showed that using 5% Ag NPs in the photoanode results in the increased efficiency, fill factor, and circuit current density from 0.28% to 0.60%, 0.22 to 0.29, and 2.18 mA/cm2 to 3.25 mA/cm2, respectively. Also, incident photon-to-current efficiencies (IPCE) results showed that cell performance improvement is related to enhanced absorption in the photoanode, which is because of the surface plasmonic resonance and light scattering of Ag NPs in the photoanode. Measurements of electrochemical impedance spectroscopy revealed that hole transfer kinetics increases with introduction of Ag NPs into photoanode. Also, it is shown that chemical capacitance increases with introduction of Ag NPs. Such increase can be attributed to the surface palsmonic resonance of Ag NPs which leads to absorption of more light in the photoanode and generation of more photoelectron in the photoanode.

  12. Enhanced DSSCs efficiency via Cooperate co-absorbance (CdS QDs) and plasmonic core-shell nanoparticle (Ag@PVP)

    PubMed Central

    Amiri, Omid; Salavati-Niasari, Masoud; Bagheri, Samira; Yousefi, Amin Termeh

    2016-01-01

    This paper describes cooperate the co-absorbance (CdS QDs) and the plasmonic core-shell nanoparticles (Ag@PVP) of dye synthesized solar cells in which CdS QDs and Ag@PVP are incorporated into the TiO2 layer. Cooperative nanoparticles show superior behavior on enhancing light absorption in comparison with reference cells. Cooperated DSSC exhibits the best performance with the power conversion efficiency of 7.64% which is superior to that of the free–modified DSSC with the PCE of 5%. Detailed studies offer an effective approach to enhance the efficiency of dye synthesized solar cells. PMID:27143126

  13. Enhanced DSSCs efficiency via Cooperate co-absorbance (CdS QDs) and plasmonic core-shell nanoparticle (Ag@PVP).

    PubMed

    Amiri, Omid; Salavati-Niasari, Masoud; Bagheri, Samira; Yousefi, Amin Termeh

    2016-01-01

    This paper describes cooperate the co-absorbance (CdS QDs) and the plasmonic core-shell nanoparticles (Ag@PVP) of dye synthesized solar cells in which CdS QDs and Ag@PVP are incorporated into the TiO2 layer. Cooperative nanoparticles show superior behavior on enhancing light absorption in comparison with reference cells. Cooperated DSSC exhibits the best performance with the power conversion efficiency of 7.64% which is superior to that of the free-modified DSSC with the PCE of 5%. Detailed studies offer an effective approach to enhance the efficiency of dye synthesized solar cells. PMID:27143126

  14. Enhanced DSSCs efficiency via Cooperate co-absorbance (CdS QDs) and plasmonic core-shell nanoparticle (Ag@PVP)

    NASA Astrophysics Data System (ADS)

    Amiri, Omid; Salavati-Niasari, Masoud; Bagheri, Samira; Yousefi, Amin Termeh

    2016-05-01

    This paper describes cooperate the co-absorbance (CdS QDs) and the plasmonic core-shell nanoparticles (Ag@PVP) of dye synthesized solar cells in which CdS QDs and Ag@PVP are incorporated into the TiO2 layer. Cooperative nanoparticles show superior behavior on enhancing light absorption in comparison with reference cells. Cooperated DSSC exhibits the best performance with the power conversion efficiency of 7.64% which is superior to that of the free–modified DSSC with the PCE of 5%. Detailed studies offer an effective approach to enhance the efficiency of dye synthesized solar cells.

  15. Phase Structures and Piezoelectric Properties of (K,Na,Li)(Nb,Sb)O3-(Bi,Ag)ZrO3 Lead-Free Ceramics

    NASA Astrophysics Data System (ADS)

    Li, ZhiPeng; Zhang, Yang; Li, LingYu; Li, JianKang; Zhai, JiWei

    2016-06-01

    Samples in the pseudoternary lead-free piezoelectric ceramic system 0.94KNN-(0.06 - x)LiSbO3- x(Bi0.5Ag0.5)ZrO3 were prepared using a solid-state reaction technique and their phase transition behavior and electrical properties studied. Results showed that BAZ diffuses into KNN-LS to form a new solid solution, and induces a phase transition from tetragonal to rhombohedral phase with increase of x. At 0.02 ≤ x ≤ 0.03, coexistence of tetragonal and rhombohedral phases is observed, and enhanced piezoelectric properties are achieved in this composition range due to the polymorphic phase transition near room temperature. Doping with (Bi0.5Ag0.5)ZrO3 effectively promotes densification and further enhances the piezoelectric and dielectric properties of of the ceramics. Moreover, the ceramic with x = 0.025 possesses excellent electrical properties of k p = 42.3%, {d_{33}^{*}} = 320 pm/V and d 33 = 235 pC/N, tan δ = 0.039, and T c = 326°C. This result indicates that 0.94KNN-0.035LS-0.025BAZ ceramic is a promising lead-free material for practical applications.

  16. Ag-clad Bi-Sr-Ca-Cu-O wires I. Phase study of fully processed 2:2:1:2 wires

    NASA Astrophysics Data System (ADS)

    Ray, R. D.; Hellstrom, E. E.

    1991-01-01

    We have studied the composition of phases in fully processed Ag-clad wires containing Bi-Sr-Ca-Cu-O with a starting cation ratio of 2:2:1:2 using electron probe microanalysis. Wires that were processed at temperatures not exceeding 850°C contained two phases: the two-CuO 2 layer superconductor (“2212”) and Bi 0.06Sr 8.87Ca 4.87Cu 24O x, which is a member of the “ {14}/{24}” solid solution that is in equilibrium with “2212” at 850°C. Phases identified in wires melt processed at temperatures up to 920°C then annealed at 830-840°C were “2212”, (Sr 1- xCa x)CuO 2, and Ag particles. This appears to be a nonequilibrium phase assemblage as the superconductor is not reported to be in equilibrium with (Sr 1- xCa x)CuO 2 at 800-850°C.

  17. Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures

    NASA Astrophysics Data System (ADS)

    Park, Jung Tae; Chi, Won Seok; Jeon, Harim; Kim, Jong Hak

    2014-02-01

    TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (η) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of η is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements.TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb

  18. Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions.

    PubMed

    Chen, Wei-Ni; Jiang, Shiuh-Jen; Chen, Yen-Ling; Sahayam, A C

    2015-02-20

    A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v L-cysteine, 0.5 μg mL(-1) Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng g(-1) for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample. PMID:25682241

  19. Effects of Ag{sub 2}O doping on the electromagnetic properties of a BiPbSrCaCuO superconductor

    SciTech Connect

    Lee, Sang Heon; Kim, H. C.

    2001-06-01

    Electromagnetic properties of an Ag{sub 2}O doped and an undoped BiPbSrCaCuO superconductor were evaluated to investigate the effect of the pinning center on the magnetic shielding and suspension/levitation phenomena. The residual magnetization M=M{sup +}{endash}M{sup {minus}} increased with the dopant concentration, a maximum for 2% doping, wherein a fine uniform dispersion of Ag particles was observed. The fine Ag particles form a cluster with increasing dopant as the particles condense with each other and grow, consequently does the number of flux passing through decreases, so the magnetization M decreases. This result indicates that M is proportional to the number of magnetic flux lines passing through the sample, because the smaller the particle size the larger the ratio of the surface area to the volume. Magnetic shielding was evaluated by measuring the induced voltage in the secondary coil by placing the sample in between the primary coil. The voltage was initially set to 0.5 V, and decreased to 0.17 and 0.28 V, respectively, for the undoped and 2% Ag{sub 2}O doped samples. The much less change in the induced voltage for the 2% doped sample is attributed to increased flux shielding by shielding the vortex current. Simultaneous stable levitation and suspension of 2% Ag{sub 2}O doped disk samples weighing 0.3 g were observed, respectively, above (3 mm) and beneath (2 mm) a toroidal permanent magnet under a field cooled condition. The role of flux pinning is discussed to account for the phenomena by considering the hysteretic force function. {copyright} 2001 American Institute of Physics.

  20. ZnO/CdS bi-layer nanostructures photoelectrode for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Dalal, Paresh V.; Deshpande, Milind P.; Solanki, Bharat G.; Soni, Saurabh S.

    2016-05-01

    Simple chemical deposition method for the synthesis of ZnO/CdS bilayer photoelectrode on fluorine doped tin oxide (FTO) coated glass substrate in aqueous medium at low temperature (< 373K) is described. The different preparative parameters such as deposition time, bath temperature, concentration of precursor solution and, pH of the bath etc. were optimized. Nanograined ZnO was deposited on FTO coated glass substrates by dip-coating method, whereas CdS nanorods were successfully synthesized on pre-deposited ZnO film by Chemical Bath Deposition (CBD) method. The Photovoltaic properties of FTO/ZnO/CdS bilayer photo electrodes were also studied. A maximum short circuit current density of 9.1 mA cm-2 and conversion efficiency 1.05% are observed for ZnO/CdS_10min. Layer, which supports fast electron injection kinetics due to hetero structured nanorod, while minimum values of 0.53mA cm-2 and 0.01% respectively are observed for only ZnO deposited layer.

  1. Structural studies of Fe{sub 2}O{sub 3}-Bi{sub 2}O{sub 3}-CdO glass system

    SciTech Connect

    Rusu, Dorina; Ardelean, I.

    2008-07-01

    xFe{sub 2}O{sub 3}.(100 - x)[Bi{sub 2}O{sub 3}.CdO] system with 0 {<=} x {<=} 50 mol% was prepared and investigated by X-ray diffraction, density, FT-IR and Raman spectroscopies. The XRD patterns confirm the formation of a vitreous structure for x < 35 mol% Fe{sub 2}O{sub 3}. The evolution of density and molar volume with the addition and increasing of iron content indicates structural changes in the structure of Bi{sub 2}O{sub 3}.CdO glass matrix. The FT-IR spectrum of the glass matrix reveals a structure realized from BiO{sub 3} pyramidal and BiO{sub 6} octahedral units. With the addition of iron the structure proposed by the glass matrix is changing by the appearance of FeO{sub 4} units. Also the existence of FeO{sub 6} units cannot be excluded. The Raman spectra suggest a structure build from BiO{sub 6} octahedral units. By Raman scattering the presence of structural units characteristic to Fe{sub 2}O{sub 3} was not directly observed but the evolution of the spectra is dependent of the iron content.

  2. 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.

  3. Structural and Magnetotransport Studies of MBE-grown Pn(Sn)Te films and PbTe:Bi/CdTe Quantum Wells

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Liu, Xinyu; Furdyna, Jacek; Dobrowolska, Malgorzata; Wojtowicz, Tomasz

    2014-03-01

    Recent studies confirmed the existence of topological crystalline insulators (TCIs), in which crystalline symmetry replaces the role of time-reversal symmetry in ensuring topological protection. In the narrow-gap semiconductor TCIs, chemical potential can be tuned by modifications of crystal growth and/or annealing to yield n-type or p-type conductivity, which makes them especially well-suited for magnetotransport measurements. In this work, we have grown a series of Pb1-xSnxTe films and PbTe:Bi/CdTe QWs on CdTe/GaAs(100) substrates using MBE. Structural studies of these thin films were carried out using XRD and SEM techniques. XRD results shows satisfactory crystal quality of Pb(Sn)Te films grown on CdTe. SEM studies show the presence of inclusions in the films, indicating that the crystal quality still requires improvement. Magnetostransport studies of PbTe:Bi/CdTe QWs suggests that Bi acts as a donor in PbTe, and the electron mobility in the 2D electron gas in the QW depends on the growth conditions, such as substrate temperature. The study of Pb1-xSnxTe QWs is currently underway, and will also be discussed in this talk.

  4. Physiological characterization of Chlamydomonas reinhardtii acclimated to chronic stress induced by Ag, Cd, Cr, Cu and Hg ions.

    PubMed

    Nowicka, Beatrycze; Pluciński, Bartosz; Kuczyńska, Paulina; Kruk, Jerzy

    2016-08-01

    Acclimation to heavy metal-induced stress is a complex phenomenon. Among the mechanisms of heavy metal toxicity, an important one is the ability to induce oxidative stress, so that the antioxidant response is crucial for providing tolerance to heavy metal ions. The effect of chronic stress induced by ions of five heavy metals, Ag, Cu, Cr (redox-active metals) Cd, Hg (nonredox-active metals) on the green microalga Chlamydomonas reinhardtii was examined at two levels - the biochemical (content of photosynthetic pigments and prenyllipid antioxidants, lipid peroxidation) and the physiological (growth rate, photosynthesis and respiration rates, induction of nonphotochemical quenching of chlorophyll fluorescence). The expression of the genes which encode the enzymes participating in the detoxification of reactive oxygen species (APX1, CAT1, FSD1, MSD1) was measured. The other gene measured was one required for plastoquinone and α-tocopherol biosynthesis (VTE3). The application of heavy metal ions partly inhibited growth and biosynthesis of chlorophyll. The growth inhibition was accompanied by enhanced lipid peroxidation. An increase in the content of prenyllipid antioxidants was observed in cultures exposed to Cr2O7(2-), Cd(2+) (α- and γ-tocopherol and plastoquinone) and Cu(2+) (only tocopherols). The induction of nonphotochemical quenching was enhanced in cultures exposed to Cu(2+), Cr2O7(2-) and Cd(2+), as compared to the control. Chronic heavy metal-induced stress led to changes in gene expression dependent on the type and concentration of heavy metal ions. The up-regulation of antioxidant enzymes was usually accompanied by the up-regulation of the VTE3 gene. PMID:27104807

  5. Transport currents in Bi-2223/Ag tapes made using the tape-in-rectangular tube process, current distribution and Ic stress degradation

    NASA Astrophysics Data System (ADS)

    Kovác, P.; Husek, I.; Melisek, T.; Metz, A.; van Eck, H. J. N.; ten Haken, B.

    2002-04-01

    Using the tape-in-rectangular tube (TIRT) process, we have made multi-core Bi-2223/Ag tapes with various numbers of filaments (10-162), and with different filament architectures and orientations. We have measured the angular dependence of the transport current of the tape samples with 'parallel' and 'perpendicular' filaments. The transversal Ic distribution obtained by spatially resolved transport measurements ('magnetic knife') illustrates that the filament quality of the TIRT tapes is better at the tape edges than in the centre. The tapes were stressed by two types of tensioning set-up (a short straight sample and a U-shaped spring) and by bending at 77 K. The Ic degradation shows different behaviour for parallel and perpendicular filaments, which is attributed to the difference in filament density and crack propagation.

  6. AC losses in BiPbSrCaCuO-2223/Ag multifilamentary tapes in conditions similar to those in superconducting transmission lines

    NASA Astrophysics Data System (ADS)

    Majoros, M.; Glowacki, B. A.; Campbell, A. M.; Han, Z.; Vase, P.

    1998-12-01

    Transport AC losses in BiPbSrCaCuO-2223/Ag multifilamentary tape with 19 filaments were measured. The sample was 1.05 m long, wound in form of a helix with a gap between the tapes comparable with the tape width. Two different types of potential leads-tape following, axis following-with taps positioned in the centre of the tape were mounted on inner as well as outer surface of the helical sample. AC losses were measured at power frequencies by an electrical method using a lock-in nanovoltmeter. The influence of potential wires arrangement and the potential taps position on measured AC loss level and its frequency dependence was analysed.

  7. Flux patterns of multifilamentary Ag-sheathed (Pb,Bi)2Sr2Ca2Cu3O10+δ tapes

    NASA Astrophysics Data System (ADS)

    Koblischka, M. R.; Johansen, T. H.; Bratsberg, H.; Půst, L.; Galkin, A.; Nálevka, P.; Maryško, M.; Jirsa, M.; Bentzon, M.; Bodin, P.; Vase, P.; Freltoft, T.

    1998-06-01

    Flux patterns of multifilamentary Ag-sheathed (Pb,Bi)2Sr2Ca2Cu3O10+δ tapes comprising 19 filaments are visualized by means of magneto-optic imaging. In low fields, the shielding currents are seen to flow mainly in the outermost filaments. With increasing external magnetic field, the inner filaments also contribute to the current flow. To compare the local flux distribution with the integral magnetization values, magnetization loops are measured by a SQUID magnetometer on the same sample following the fields used in the magneto-optic imaging (± 120 mT) and covering fields up to ±5 T at various temperatures. The magnetization loops also reveal that the multifilamentary tapes show the anomalous position of the central peak, but always less pronounced than in monofilamentary tapes.

  8. A new structural powder/wire-in-tube (PWIT) Ag-sheathed multifilamentary Bi-2223 tape and its superconducting properties

    NASA Astrophysics Data System (ADS)

    Zeng, R.; Liu, H. K.; Dou, S. X.

    1998-05-01

    A new design of macrostructural multifilamentary tapes has been developed by parking powder and composite wires into the silver tube (PWIT) at the second stage of the powder-in-tube (PIT) process. The critical current Jc and the strain tolerance for this PWIT multifilamentary tape were significantly improved in comparison with the PIT multifilamentary tapes. The enhancement of both Jc and the strain tolerance are attributable to the increased interface between Ag and oxide superconductor. We have introduced a simple concept of the periphery length of the Ag/superconductor interface per unit area in the cross-section of tapes ( E) and have compared its properties in PWIT and PIT tapes. Both Jc and the strain tolerance were improved with increasing E. This was attributed to the improved grain alignment and crack elimination at the Ag/superconductor interface. The Jc- B properties and the Jc-strain characteristic of two tapes have been compared.

  9. Metal (Ag, Cd, Cu, Ni, Tl, and Zn) Binding to Cytosolic Biomolecules in Field-Collected Larvae of the Insect Chaoborus.

    PubMed

    Rosabal, Maikel; Mounicou, Sandra; Hare, Landis; Campbell, Peter G C

    2016-03-15

    We characterized the biomolecules involved in handling cytosolic metals in larvae of the phantom midge (Chaoborus) collected from five mining-impacted lakes by determining the distribution of Ag, Cd, Cu, Ni, Tl, and Zn among pools of various molecular weights (HMW: high molecular weight, >670-40 kDa; MMW: medium molecular weight, 40-<1.3 kDa; LMW: low molecular weight, <1.3 kDa). Appreciable concentrations of nonessential metals were found in the potentially metal-sensitive HMW (Ag and Ni) and LMW (Tl) pools, whereas the MMW pool, which includes metallothioneins (MTs) and metallothionein-like proteins and peptides (MTLPs), appears to be involved in Ag and Cd detoxification. Higher-resolution fractionation of the heat-stable protein (HSP) fraction revealed further differences in the partitioning of nonessential metals (i.e., Ag = Cd ≠ Ni ≠ Tl). These results provide unprecedented details about the metal-handling strategies employed by a metal-tolerant, freshwater animal in a field situation. PMID:26886407

  10. Cluster formation in Ag{sub 2}O-P{sub 2}O{sub 5}-CdCl{sub 2} glass system

    SciTech Connect

    Das, S.S.; Singh, N.B.

    2008-11-03

    Ag{sub 2}O-P{sub 2}O{sub 5} and Ag{sub 2}O-P{sub 2}O{sub 5}-20 wt% CdCl{sub 2} glasses were prepared by melt quenching method and characterized with the help of several experimental techniques. Powder X-ray diffraction study indicated that the glasses are amorphous in nature. DSC studies showed that CdCl{sub 2} doped glass is chemically more durable. Electrical conductivity and ionic transference number measurements have shown that both the glasses are ionic conductors with Ag{sup +} ions as the charge carriers. The electrical conductivity of the doped glass is found to be higher than the undoped one. Structures of the glasses have been proposed on the basis of IR spectral analysis. From SEM studies it has been inferred that addition of 20 wt% CdCl{sub 2} modifies the morphology of Ag{sub 2}O-P{sub 2}O{sub 5} glass and in its presence formation of clusters composed of nanofibers occur.

  11. Two-dimensional X-ray diffraction characterization of (Zn,Cd,Mg)Se wurtzite layers grown on Bi2Se3

    NASA Astrophysics Data System (ADS)

    Hernandez-Mainet, L. C.; Chen, Z.; Garcia, T. A.; Bykov, A. B.; Krusin-Elbaum, L.; Tamargo, M. C.

    2016-01-01

    ZnSe, Zn0.49Cd0.51Se and Zn0.23Cd0.25Mg0.52Se layers grown on Bi2Se3/sapphire (0001) by molecular beam epitaxy (MBE) are characterized by two-dimensional X-ray diffraction. Pole figures are calculated for cubic and hexagonal planes of the (Zn,Cd,Mg)Se family and compared to their expected values. The targeted wurtzite plane was (11-22), while the cubic ones were the (220) and (311). The results show that, under our MBE growth conditions, ZnSe, Zn0.49Cd0.51Se and Zn0.23Cd0.25Mg0.52Se layers prefer to form the hexagonal (wurtzite) phase rather than the cubic one when grown on Bi2Se3/sapphire in (0001) direction. These results have implications for the next generation devices combining semiconductors and topological insulator materials.

  12. International round robin test of the retained critical current after double bending at room temperature of Ag-sheathed Bi-2223 superconducting wires

    NASA Astrophysics Data System (ADS)

    Yamada, Y.; Nishijima, G.; Osamura, K.; Shin, H. S.; Goldacker, W.; Breschi, M.; Ribani, P.

    2016-02-01

    An international round robin test was carried out in order to establish a test method for retained critical current after double bending at room temperature of Ag-sheathed Bi-2223 superconducting wires. Tests for commercial Bi-2223 tape were conducted by six laboratories using the same guidelines. The standard uncertainties (SUs) of measurands were evaluated for these four quantities: I C0, I C/I C080, I C/I C060, I C/I C050, where, I C0 is initial critical current and I C /I C0XX is critical current after XX mm bending. Using an F test to determine where the most scatter was generated in the test results it was found that the greatest scatter in the normalized critical current measurements came from inter-laboratory scatter. In a type-B uncertainty evaluation, the major contribution was from the bending diameter and measuring temperature. The relative SU tended to increase as the bending diameter decreased. A specific mandrel diameter corresponding to a retained critical current of 95% could be determined with a relative SU of 1.3%. In order to reduce the overall scatter, the temperature difference between the critical current measurements before and after bending should be small.

  13. Cation ordering and physicochemical characterization of the quaternary diamond-like semiconductor Ag{sub 2}CdGeS{sub 4}

    SciTech Connect

    Brunetta, Carl D.; Minsterman, William C.; Lake, Charles H.; Aitken, Jennifer A.

    2012-03-15

    The quaternary diamond-like semiconductor, Ag{sub 2}CdGeS{sub 4}, was synthesized via high-temperature solid-state synthesis as well as structurally and physicochemically characterized. Single crystal X-ray diffraction provided a model for Ag{sub 2}CdGeS{sub 4} in the orthorhombic, noncentrosymmetric space group Pna2{sub 1} with a=13.7415(8) A, b=8.0367(5) A and c=6.5907(4) A, in contrast to a previously published model in Pmn2{sub 1} from the Rietveld analysis of laboratory X-ray powder diffraction data. The Pna2{sub 1} space group is supported by the Rietveld analysis of synchrotron X-ray powder diffraction data. Differential thermal analysis suggests that Ag{sub 2}CdGeS{sub 4} exists in two polymorphs. Optical diffuse reflectance UV/vis/NIR spectroscopy indicates that the orange compound is a semiconductor with a band gap of 2.32 eV. Optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and inductively coupled plasma optical emission spectroscopy were used to further characterize the material. - Graphical abstract: The structure of the diamond-like semiconductor Ag{sub 2}CdGeS{sub 4} has been solved and refined in the orthorhombic noncentrosymmetric space group Pna2{sub 1}. A view down the a-axis shows that all MS{sub 4} tetrahedra are pointing in the same direction along the c-axis. The structure can be derived from that of lonsdaleite. Highlights: Black-Right-Pointing-Pointer The structure of Ag{sub 2}CdGeS{sub 4} is solved from single crystal X-ray diffraction. Black-Right-Pointing-Pointer The structure is supported by the Rietveld analysis of synchrotron diffraction data. Black-Right-Pointing-Pointer Ag{sub 2}CdGeS{sub 4} is a semiconductor with an optical band gap of 2.32 eV. Black-Right-Pointing-Pointer Additional characterization is reported.

  14. Oxygen vacancies induced switchable and nonswitchable photovoltaic effects in Ag/Bi0.9La0.1FeO3 /La0.7Sr0.3MnO3 sandwiched capacitors

    NASA Astrophysics Data System (ADS)

    Gao, R. L.; Yang, H. W.; Chen, Y. S.; Sun, J. R.; Zhao, Y. G.; Shen, B. G.

    2014-01-01

    The short circuit photocurrent (Isc) was found to be strongly dependent on the oxygen vacancies (VOs) distribution in Ag/Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 heterostructures. In order to manipulate the VOs accumulated at either the Ag/Bi0.9La0.1FeO3 or the Bi0.9La0.1FeO3/La0.7Sr0.3MnO3 interface by pulse voltages, switchable or nonswitchable photocurrent can be observed without or with changing the polarization direction. The sign of photocurrent could be independent of the direction of polarization when the variation of diffusion current and the modulation of the Schottky barrier at the Ag/Bi0.9La0.1FeO3 interface induced by oxygen vacancies are large enough to offset those induced by polarization. Our work provides deep insights into the nature of photovoltaic effects in ferroelectric films, and will facilitate the advanced design of switchable devices combining spintronic, electronic, and optical functionalities.

  15. Core-shell Cd0.2Zn0.8S@BiOX (X = Cl, Br and I) microspheres: a family of hetero-structured catalysts with adjustable bandgaps, enhanced stability and photocatalytic performance under visible light irradiation.

    PubMed

    Zhou, Yannan; Wen, Ting; Chang, Binbin; Yang, Baocheng; Wang, Yonggang

    2016-09-21

    Heterostructures consisting of two semiconductors have merited considerable attention in photocatalytic applications due to synergistic effects in complex redox processes. The incorporation of solid solutions into such architectures can further offer extra variability to control the bandgap. In this study, we report the fabrication of a series of core-shell Cd0.2Zn0.8S@BiOX (X = Cl, Br and I) microspheres via a solvothermal route that lead to enhanced photocatalytic performance under visible light irradiation. By optimizing the synthesis conditions, uniform and porous Cd0.2Zn0.8S@BiOX microspheres were achieved. The products were thoroughly characterized by X-ray diffraction studies, scanning electron microscopy, transmission electron microscopy, photoluminescence studies, absorption measurements and the photodegradation of RhB. Remarkably, the electronic structures of Cd0.2Zn0.8S@BiOX composites can be continuously tuned by varying the composition of BiOX to achieve the best catalytic performance under visible light irradiation. Finally, this greatly enhanced visible-light-driven photocatalytic efficiency was observed in the optimized Cd0.2Zn0.8S@BiOI composites when compared to their single-component counterparts, which may be attributed to increased light absorption and improved electron-hole separation. The photocatalytic mechanism has also been proposed based on the experimental evidences and the theoretical band positions of Cd0.2Zn0.8S@BiOI. PMID:27510184

  16. Performance of LaBaCo 2O 5+ δ-Ag with B 2O 3-Bi 2O 3-PbO frit composite cathodes for intermediate-temperature solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Ruifeng; Gao, Lei; Ge, Lin; Zheng, Yifeng; Zhou, Ming; Chen, Han; Guo, Lucun

    The composite cathodes LaBaCo 2O 5+ δ- x wt.% Ag (LBCO- xAg, x = 20, 30, 40, 50) were prepared by mechanical mixing method for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The experiment results indicated that the addition of a small amount of B 2O 3-Bi 2O 3-PbO (BBP) frit to LBCO- xAg can effectively improve the adhesion and strength of cathode membrane without damaging its porous structure. The BBP frit was proved effective for lowering the sintering temperature of LBCO- xAg to 900 °C. According to the electrochemical impedance spectroscopy and cathodic polarization analysis, the LBCO-30Ag exhibited the best performance and the optimal BBP frit content was 2.5 wt.%. For LBCO-30Ag with 2.5 wt.% BBP frit, the area-specific resistance based on Sm 0.2Ce 0.8O 1.9 (SDC) electrolyte decreased by about 57.6% at 700 °C, 60.5% at 750 °C and 75.9% at 800 °C compared to LBCO, and its cathodic overpotential was 10.7 mV at a current density of 0.2 A cm -2 at 700 °C, while the corresponding value for LBCO was 51.0 mV. The addition of Ag and BBP frit to LBCO had no significant effect on the thermal expansion.

  17. Enhancement of the power factor of [Bi 1.68Ca 2O 4] RS[CoO 2] 1.69 - Ag composites prepared by the spray-drying method

    NASA Astrophysics Data System (ADS)

    Rivas-Murias, B.; Muguerra, H.; Traianidis, M.; Henrist, C.; Vertruyen, B.; Cloots, R.

    2010-08-01

    [Bi 1.68Ca 2O 4] RS[CoO 2] 1.69 (BCCO) sample and Ag-BCCO composites (with 10, 20 or 30 wt% Ag) have been prepared by the spray-drying technique and uniaxially/isostatically packed. Scanning electron microscopy reveals that the Ag particles are well distributed in the BCCO cobaltite matrix at low Ag contents. The Ag particles have an important effect on densification and grain orientation of the samples, with a direct impact on their electrical conductivity. The electrical conductivity is higher for the uniaxial samples and increases with the Ag content up to 20% in weight, while the Seebeck coefficient is hardly affected. These features induce an improvement of the power factor, reaching a maximum value of 2.2 μW K -2 cm -1 at ˜1050 K for the uniaxial sample with 20 wt% Ag. Our results suggest that the spray-drying technique is a promising method to obtain composites with a well-dispersed secondary phase.

  18. Hydrothermal synthesis of CdS/Bi2MoO6 heterojunction photocatalysts with excellent visible-light-driven photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Feng, Yi; Yan, Xu; Liu, Chunbo; Hong, Yuanzhi; Zhu, Lin; Zhou, Mingjun; Shi, Weidong

    2015-10-01

    A novel CdS/Bi2MoO6 heterojunction photocatalysts were successfully prepared via two-step hydrothermal methods. The prepared samples were characterized by various physicochemical techniques, such as XRD, SEM, TEM, HRTEM, XPS, UV-vis and PL. The obtained samples exhibited highly photocatalytic activity toward the degradation of the different kinds of organic dyes and tetracycline in aqueous solution under visible light irradiation (λ > 420 nm). The optimum photocatalytic efficiency of CdS-2 sample for the degradation rhodamine B (RhB) was about 25.3 and 3.7 times higher than that of individual CdS and Bi2MoO6, respectively. In addition, the possible photocatalytic mechanism was analyzed by different active species trapping experiments. The results indicated that the h+ and rad O2- were the main active species for the photocatalytic degradation of RhB. Moreover, the prepared sample shows good stability and recyclability properties which are beneficial for its practical application.

  19. Structure, phase evolution, and microwave dielectric properties of (Ag0.5Bi0.5)(Mo0.5W0.5)O4 ceramic with ultralow sintering temperature.

    PubMed

    Zhou, Di; Li, Wen-Bo; Guo, Jing; Pang, Li-Xia; Qi, Ze-Ming; Shao, Tao; Xie, Hui-Dong; Yue, Zhen-Xing; Yao, Xi

    2014-06-01

    In the present work, the microwave dielectric ceramic (Ag0.5Bi0.5)(Mo0.5W0.5)O4 was prepared by using the solid-state reaction method. (Ag0.5Bi0.5)(Mo0.5W0.5)O4 was found to crystallize in the scheelite structure, in which Ag(+) and Bi(3+) occupy the A site randomly with 8-coordination while Mo(6+) and W(6+) occupy the B site with 4-coordination, at a sintering temperature above 500 °C, with lattice parameters a = b = 5.29469(2) Å and c = 11.62114(0) Å, space group I4(1)/a (No. 88), and acceptable Rp = 9.38, Rwp = 11.2, and Rexp = 5.86. High-performance microwave dielectric properties, with permittivity ∼26.3, Qf value ∼10,000 GHz, and temperature coefficient ∼+20 ppm/°C, were obtained in the sample sintered at 580 °C. Its chemical compatibility with aluminum at its sintering temperature was revealed and confirmed by both X-ray and energy dispersive spectrometer analysis. This ceramic could be a good candidate for ultralow-temperature cofired ceramics. PMID:24848200

  20. Apparent ac losses in helical BiPbSrCaCuO-2223/Ag multifilamentary tape measured by different potential taps at power frequencies

    NASA Astrophysics Data System (ADS)

    Majoros, M.; Glowacki, B. A.; Campbell, A. M.; Han, Z.; Vase, P.

    1999-03-01

    Transport ac losses in BiPbSrCaCuO-2223/Ag multifilamentary tape in form of a helix with a 3 mm gap between the turns were measured in frequency range 40-125 Hz. Different positions of potential taps on outer and inner surface of the tape were used. Potential wires were led along the tape axis as well as along the axis of the helix. At currents lower than the critical current a strong dependence of measured apparent ac losses on potential taps position and on the form of potential wires was found. Suitably wound contact-less pick-up coils to detect magnetic flux of different magnetic field components were also used. They allowed us to measure the `magnetisation' part of apparent losses even when the sample was in resistive state, as well as the losses at the gap of the tape. Comparison of the losses at the gap of the tape with the existing theoretical model was made.

  1. Refinement of the Microstructure of Sn-Ag-Bi-In Solder, by Addition of SiC Nanoparticles, to Reduce Electromigration Damage Under High Electric Current

    NASA Astrophysics Data System (ADS)

    Kim, Youngseok; Nagao, Shijo; Sugahara, Tohru; Suganuma, Katsuaki; Ueshima, Minoru; Albrecht, Hans-Juergen; Wilke, Klaus; Strogies, Joerg

    2014-12-01

    The trends of miniaturization, multi-functionality, and high performance in advanced electronic devices require higher densities of I/O gates and reduced area of soldering of interconnections. This increases the electric current density flowing through the interconnections, increasing the risk of interconnection failure caused by electromigration (EM). Accelerated directional atomic diffusion in solder materials under high current induces substantial growth of intermetallic compounds (IMCs) at the anode, and also void and crack formation at the cathode. In the work discussed in this paper, addition of SiC nanoparticles to Sn-Ag-Bi-In (SABI) lead-free solder refined its microstructure and improved its EM reliability under high current stress. Electron backscattering diffraction analysis revealed that the added SiC nanoparticles refined solder grain size after typical reflow. Under current stress, SABI joints with added nano-SiC had lifetimes almost twice as long as those without. Comparison of results from high-temperature aging revealed direct current affected evolution of the microstructure. Observations of IMC growth indicated that diffusion of Cu in the SiC composite solder may not have been reduced. During current flow, however, only narrow voids were formed in solder containing SiC, thus preventing the current crowding caused by bulky voids in the solder without SiC.

  2. Effect of preparation procedure and nanostructuring on the thermoelectric properties of the lead telluride-based material system AgPbmBiTe2+m (BLST-m)

    NASA Astrophysics Data System (ADS)

    Falkenbach, Oliver; Schmitz, Andreas; Hartung, David; Dankwort, Torben; Koch, Guenter; Kienle, Lorenz; Klar, Peter J.; Mueller, Eckhard; Schlecht, Sabine

    2016-06-01

    We report on the preparation and thermoelectric properties of the quaternary system AgPbmBiTe2+m (Bismuth-Lead-Silver-Tellurium, BLST-m) that were nanostructured by mechanical alloying. Nanopowders of various compositions were compacted by three different methods: cold pressing/annealing, hot pressing, and short term sintering. The products are compared with respect to microstructure and sample density. The thermoelectric properties were measured: thermal conductivity in the temperature range from 300 K to 800 K and electrical conductivity and Seebeck coefficient between 100 K and 800 K. The compacting method and the composition had a substantial impact on carrier concentration and mobility as well as on the thermoelectric parameters. Room temperature Hall measurements yielded carrier concentrations in the order of 1019 cm-3, slightly increasing with increasing content of the additive silver bismuth telluride to the lead telluride base. ZT values close to the ones of bulk samples were achieved. X-ray diffraction and transmission electron microscopy (TEM) showed macroscopically homogeneous distributions of the constituting elements inside the nanopowders ensembles, indicating a solid solution. However, high resolution transmission electron microscopy (HRTEM) revealed disorder on the nanoscale inside individual nanopowders grains.

  3. Studies of the spin Hamiltonian parameters and defect structures for Ag2+ in NaF and CsCdF3 crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Juan; Wu, Shao-Yi; Ding, Chang-Chun; Hu, Xian-Fen; He, Jia-Jun

    2016-03-01

    The spin Hamiltonian parameters (g factors g//, g⊥, hyperfine structure constants A//, A⊥ and superhyperfine parameters Az‧, Ax‧ and Ay‧) and defect structures for Ag2+ in NaF and CsCdF3 crystals are theoretically studied using the improved perturbation formulas of these quantities for a 4d9 ion in a tetragonally elongated octahedron. The contributions from both the crystal-field and charge transfer mechanisms are taken into account, and the relevant model parameters are quantitatively obtained from the cluster approach in a consistent way. The impurity centers are found to undergo the relative tetragonal elongations of about 9.4% and 8.2% for Ag2+ in NaF and CsCdF3, respectively, along the C4 axis due to the Jahn-Teller effect. By employing the few adjustable parameters, the calculated spin Hamiltonian parameters based on the above uniform formulas and the local tetragonal elongation distortions agree well with the experimental data. Despite dominant ionicity of the hosts, the charge transfer contributions are actually important to the spin Hamiltonian parameters (e.g., about 20% for the g-shifts) due to strong covalency of impurity Ag2+.

  4. Metals (Ag(+) , Cd(2+) , Cr(6+) ) affect ATPase activity in the gill, kidney, and muscle of freshwater fish Oreochromis niloticus following acute and chronic exposures.

    PubMed

    Atli, Gülüzar; Canli, Mustdafa

    2013-12-01

    Freshwater fish Oreochromis niloticus were individually acutely exposed to different concentrations (0, 0.1, 0.5, 1.0, and 1.5 μg/mL) of Cd(2+) , Cr(6+) , and Ag(+) for 96 h and 0.05 μg/mL concentration of the same metals for different periods (0, 5, 10, 20, and 30 days) chronically. Following each experimental protocol, Na(+) /K(+) -ATPase, Mg(2+) -ATPase, and Ca(2+) -ATPase activities were measured in the gill, kidney, and muscle of O. niloticus. In vitro experiments were also performed to determine the direct effects of metal ions (0, 0.1, 0.5, 1.0, and 1.5 μg/mL) on ATPases. Except Ag(+) , none of the metals caused fish mortality within 30 days. Silver killed all the fishes within 16 days. Metal exposures generally decreased Na(+) /K(+) -ATPase and Ca(2+) -ATPase activities in the tissues of O. niloticus, although there were some fluctuations in Mg(2+) -ATPase activity. Ag(+) and Cd(2+) were found to be more toxic to ATPase activities than Cr(6+) . It was also observed that metal efficiency was higher in the gill than in the other tissues. Results indicated that the response of ATPases varied depending on metals, exposure types, and tissues. Because ATPases are sensitive to metal toxicity, their activity can give valuable data about fish physiology. Therefore, they may be used as a sensitive biomarker in environmental monitoring in contaminated waters. PMID:21901811

  5. Blockade of the PD-1/PD-L1 axis augments lysis of AML cells by the CD33/CD3 BiTE antibody construct AMG 330: reversing a T-cell-induced immune escape mechanism.

    PubMed

    Krupka, C; Kufer, P; Kischel, R; Zugmaier, G; Lichtenegger, F S; Köhnke, T; Vick, B; Jeremias, I; Metzeler, K H; Altmann, T; Schneider, S; Fiegl, M; Spiekermann, K; Bauerle, P A; Hiddemann, W; Riethmüller, G; Subklewe, M

    2016-02-01

    Bispecific T-cell engagers (BiTEs) are very effective in recruiting and activating T cells. We tested the cytotoxicity of the CD33/CD3 BiTE antibody construct AMG 330 on primary acute myeloid leukemia (AML) cells ex vivo and characterized parameters contributing to antileukemic cytolytic activity. The E:T ratio and the CD33 expression level significantly influenced lysis kinetics in long-term cultures of primary AML cells (n=38). AMG 330 induced T-cell-mediated proinflammatory conditions, favoring the upregulation of immune checkpoints on target and effector cells. Although not constitutively expressed at the time of primary diagnosis (n=123), PD-L1 was strongly upregulated on primary AML cells upon AMG 330 addition to ex vivo cultures (n=27, P<0.0001). This phenomenon was cytokine-driven as the sole addition of interferon (IFN)-γ and tumor necrosis factor-α also induced expression. Through blockade of the PD-1/PD-L1 interaction, AMG 330-mediated lysis (n=9, P=0.03), T-cell proliferation (n=9, P=0.01) and IFN-γ secretion (n=8, P=0.008) were significantly enhanced. The combinatorial approach was most beneficial in settings of protracted AML cell lysis. Taken together, we have characterized a critical resistance mechanism employed by primary AML cells under AMG 330-mediated proinflammatory conditions. Our results support the evaluation of checkpoint molecules in upcoming clinical trials with AMG 330 to enhance BiTE antibody construct-mediated cytotoxicity. PMID:26239198

  6. Reduced Magnetization and Loss in Ag-Mg Sheathed Bi2212 Wires: Systematics With Sample Twist Pitch and Length

    SciTech Connect

    Myers, C. S.; Susner, M. A.; Miao, H.; Huang, Y.; Sumption, M. D.; Collings, E. W.

    2014-11-20

    Suppression of magnetization and effective filament diameter (deff) with twisting was investigated for a series of recent Bi2212 strands manufactured by Oxford Superconducting Technologies. We measured magnetization as a function of field (out to 14 T), at 5.1 K, of twisted and nontwisted 37 × 18 double restack design strands. The samples were helical coils 5-6 mm in height and approximately 5 mm in diameter. The strand diameter was 0.8 mm. The magnetization of samples having twist pitches of 25.4, 12.7, and 6.35 mm were examined and compared to nontwisted samples of the same filament configuration. The critical state model was used to extract the 12-T deff from magnetization data for comparison. Twisting the samples reduced deff by a factor of 1.5-3. The deff was shown to increase both with L and Lp. Mathematical expressions, based upon the anisotropic continuum model, were fit to the data, and a parameter γ2, which quantifies the electrical connectivity perpendicular to the filament axis, was extracted. The bundle-to-bundle connectivity along the radial axis was found to be approximately 0.2%. The deff was substantially reduced with Lp. In addition, the importance of understanding sample length dependence for quantitative measurements is discussed.

  7. Reduced Magnetization and Loss in Ag-Mg Sheathed Bi2212 Wires: Systematics With Sample Twist Pitch and Length

    DOE PAGESBeta

    Myers, C. S.; Susner, M. A.; Miao, H.; Huang, Y.; Sumption, M. D.; Collings, E. W.

    2014-11-20

    Suppression of magnetization and effective filament diameter (deff) with twisting was investigated for a series of recent Bi2212 strands manufactured by Oxford Superconducting Technologies. We measured magnetization as a function of field (out to 14 T), at 5.1 K, of twisted and nontwisted 37 × 18 double restack design strands. The samples were helical coils 5-6 mm in height and approximately 5 mm in diameter. The strand diameter was 0.8 mm. The magnetization of samples having twist pitches of 25.4, 12.7, and 6.35 mm were examined and compared to nontwisted samples of the same filament configuration. The critical state modelmore » was used to extract the 12-T deff from magnetization data for comparison. Twisting the samples reduced deff by a factor of 1.5-3. The deff was shown to increase both with L and Lp. Mathematical expressions, based upon the anisotropic continuum model, were fit to the data, and a parameter γ2, which quantifies the electrical connectivity perpendicular to the filament axis, was extracted. The bundle-to-bundle connectivity along the radial axis was found to be approximately 0.2%. The deff was substantially reduced with Lp. In addition, the importance of understanding sample length dependence for quantitative measurements is discussed.« less

  8. Partitioning of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide phases and hydrous basanite melt at upper mantle conditions

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Audétat, Andreas

    2012-11-01

    The partitioning of 15 major to trace metals between monosulfide solid solution (MSS), sulfide liquid (SL) and mafic silicate melt (SM) was determined in piston-cylinder experiments performed at 1175-1300 °C, 1.5-3.0 GPa and oxygen fugacities ranging from 3.1 log units below to 1.0 log units above the quartz-fayalite-magnetite fO2 buffer, which conditions are representative of partial melting in the upper mantle in different tectonic settings. The silicate melt was produced by partial melting of a natural, amphibole-rich mantle source rock, resulting in hydrous (˜5 wt% H2O) basanitic melts similar to low-degree partial melts of metasomatized mantle, whereas the major element composition of the starting sulfide (˜52 wt% Fe; 39 wt% S; 7 wt% Ni; 2 wt% Cu) was similar to the average composition of sulfides in this environment. SL/SM partition coefficients are high (≥100) for Au, Ni, Cu, Ag, Bi, intermediate (1-100) for Co, Pb, Sn, Sb (±As, Mo), and low (≤1) for the remaining elements. MSS/SM partition coefficients are generally lower than SL/SM partition coefficients and are high (≥100) for Ni, Cu, Au, intermediate (1-100) for Co, AgBi, Mo), and low (≤1) for the remaining elements. Most sulfide-silicate melt partition coefficients vary as a function of fO2, with Mo, Bi, As (±W) varying by a factor >10 over the investigated fO2 range, Sb, Ag, Sn (±V) varying by a factor of 3-10, and Pb, Cu, Ni, Co, Au, Zn, Mn varying by a factor of 3-10. The partitioning data were used to model the behavior of Cu, Au, Ag, and Bi during partial melting of upper mantle and during fractional crystallization of primitive MORB and arc magmas. Sulfide phase relationships and comparison of the modeling results with reported Cu, Au, Ag, and Bi concentrations from MORB and arc magmas suggest that: (i) MSS is the dominant sulfide in the source region of arc magmas, and thus that Au/Cu ratios in the silicate melt and residual sulfides may decrease with increasing degree of

  9. Effects of metal-bearing nanoparticles (Ag, Au, CdS, ZnO, SiO2) on developing zebrafish embryos.

    PubMed

    Lacave, José María; Retuerto, Ander; Vicario-Parés, Unai; Gilliland, Douglas; Oron, Miriam; Cajaraville, Miren P; Orbea, Amaia

    2016-08-12

    Due to the increasing commercialization of consumer and industrial products containing nanoparticles (NPs), an increase in the introduction of these materials into the environment is expected. NP toxicity to aquatic organisms depends on multiple biotic and abiotic factors, resulting in an unlimited number of combinations impossible to test in practice. The zebrafish embryo model offers a useful screening tool to test and rank the toxicity of nanomaterials according to those diverse factors. This work aims to study the acute and sublethal toxicity of a set of metal-bearing NPs displaying different properties, in comparison to that of the ionic and bulk forms of the metals, in order to establish a toxicity ranking. Soluble NPs (Ag, CdS and ZnO) showed the highest acute and sublethal toxicity, with LC50 values as low as 0.529 mg Ag l(-1) for Ag NPs of 20 nm, and a significant increase in the malformation prevalence in embryos exposed to 0.1 mg Cd l(-1) of CdS NPs of ∼4 nm. For insoluble NPs, like SiO2 NPs, acute effects were not observed during early embryo development due to the protective effect of the chorion. But effects on larvae could be expected, since deposition of fluorescent SiO2 NPs over the gill lamella and excretion through the intestine were observed after hatching. In other cases, such as for gold NPs, the toxicity could be attributed to the presence of additives (sodium citrate) in the NP suspension, as they displayed a similar toxicity when tested separately. Overall, the results indicated that toxicity to zebrafish embryos depends primarily on the chemical composition and, thus, the solubility of the NPs. Other characteristics, such as size, played a secondary role. This was supported by the observation that ionic forms of the metals were always more toxic than the nano forms, and bulk forms were the least toxic to the developing zebrafish embryos. PMID:27363512

  10. Effects of metal-bearing nanoparticles (Ag, Au, CdS, ZnO, SiO2) on developing zebrafish embryos

    NASA Astrophysics Data System (ADS)

    María Lacave, José; Retuerto, Ander; Vicario-Parés, Unai; Gilliland, Douglas; Oron, Miriam; Cajaraville, Miren P.; Orbea, Amaia

    2016-08-01

    Due to the increasing commercialization of consumer and industrial products containing nanoparticles (NPs), an increase in the introduction of these materials into the environment is expected. NP toxicity to aquatic organisms depends on multiple biotic and abiotic factors, resulting in an unlimited number of combinations impossible to test in practice. The zebrafish embryo model offers a useful screening tool to test and rank the toxicity of nanomaterials according to those diverse factors. This work aims to study the acute and sublethal toxicity of a set of metal-bearing NPs displaying different properties, in comparison to that of the ionic and bulk forms of the metals, in order to establish a toxicity ranking. Soluble NPs (Ag, CdS and ZnO) showed the highest acute and sublethal toxicity, with LC50 values as low as 0.529 mg Ag l‑1 for Ag NPs of 20 nm, and a significant increase in the malformation prevalence in embryos exposed to 0.1 mg Cd l‑1 of CdS NPs of ∼4 nm. For insoluble NPs, like SiO2 NPs, acute effects were not observed during early embryo development due to the protective effect of the chorion. But effects on larvae could be expected, since deposition of fluorescent SiO2 NPs over the gill lamella and excretion through the intestine were observed after hatching. In other cases, such as for gold NPs, the toxicity could be attributed to the presence of additives (sodium citrate) in the NP suspension, as they displayed a similar toxicity when tested separately. Overall, the results indicated that toxicity to zebrafish embryos depends primarily on the chemical composition and, thus, the solubility of the NPs. Other characteristics, such as size, played a secondary role. This was supported by the observation that ionic forms of the metals were always more toxic than the nano forms, and bulk forms were the least toxic to the developing zebrafish embryos.

  11. Feasible voltage-tap based quench detection in a Ag/Bi-2212 coil enabled by fast 3D normal zone propagation

    DOE PAGESBeta

    Shen, Tengming; Ye, Liyang; Li, Pei

    2016-07-01

    For this study, small insert solenoids have been built using a commercial Ag/Bi-2212 multifilamentary round wire, insulated with a new thin TiO2– polymer coating insulation (thickness in ~20 μm versus ~100 μm for a commonly used mullite braided sleeve insulation), and characterized in background magnetic field up to 14 T at 4.2 K to explore the high-field performance and quench detection of Bi-2212 magnets. The coil has no visible leakage and no electrical shorts after reaction, and it carries 280 A/mm-2 in a background field 14 T and generates an additional 1.7 T. A notable result is that, despite normalmore » zones propagate slowly along the conductor, the hot spot temperature upon detection increases only from 40 K to 60 K when the resistive quench detection voltage threshold increases from 0.1 V to 1 V for all operating current density investigated, showing that quench detection using voltage taps is feasible for this coil. This is in a strong contrast to a coil we previously built to the same specifications but from wires insulated with the mullite braided sleeve insulation, for which the hot spot temperature upon detection increases from ~80 K to ~140 K while increasing from the detection voltage threshold from 0.1 V to 1 V, and thus for which quench detection using voltage taps presents significant risks, consistent with the common belief that the effectiveness of quench detection using voltage taps for superconducting magnets built using high temperature superconductors is seriously compromised by their slow normal zone propagation. This striking difference is ascribed to the fast transverse quench propagation enabled by thin insulation and improved thermal coupling between conductor turns. Finally, this work demonstrates that quench detection for high-temperature superconducting magnets highly depends on the design and construction of the coils such as insulation materials used and this dependence should be factored into the overall magnet design.« less

  12. Feasible voltage-tap based quench detection in a Ag/Bi-2212 coil enabled by fast 3D normal zone propagation

    NASA Astrophysics Data System (ADS)

    Shen, Tengming; Ye, Liyang; Li, Pei

    2016-08-01

    Small insert solenoids have been built using a commercial Ag/Bi-2212 multifilamentary round wire, insulated with a new thin TiO2–polymer coating insulation (thickness of ∼20 μm versus ∼100 μm for a commonly used mullite braided sleeve insulation), and characterized in a background magnetic field up to 14 T at 4.2 K to explore the high-field performance and quench detection of Bi-2212 magnets. The coil has no visible leakage and no electrical shorts after reaction, and it carries 280 A mm‑2 in a background field of 14 T and generates an additional 1.7 T. A notable result is that, despite normal zones propagating slowly along the conductor, the hot spot temperature upon detection increases only from 40 K to 60 K when the resistive quench detection voltage threshold increases from 0.1 V to 1 V for all operating current density investigated, showing that quench detection using voltage taps is feasible for this coil. This is in strong contrast to a coil we have previously built to the same specifications but from wires insulated with mullite braided sleeve insulation, for which the hot spot temperature upon detection increases from ∼80 K to ∼140 K while increasing the detection voltage threshold from 0.1 V to 1 V, and thus for which quench detection using voltage taps presents significant risks, consistent with the common belief that the effectiveness of quench detection using voltage taps for superconducting magnets built using high-temperature superconductors is seriously compromised by their slow normal zone propagation. This striking difference is ascribed to the fast transverse quench propagation enabled by thin insulation and the improved thermal coupling between conductor turns. This work demonstrates that quench detection for high-temperature superconducting magnets highly depends on the design and construction of the coils such as the insulation materials used and this dependence should be factored into the overall magnet design.

  13. 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.

  14. Influence of technological defects on the optical and photoelectric properties of AgCd{sub 2-x}Mn{sub x}GaSe{sub 4} alloys

    SciTech Connect

    Tretyak, A. P. Davydyuk, H. Ye.; Bozhko, V. V.; Bulatetska, L. V.; Parasyuk, O. V.

    2012-03-15

    The study is concerned with the photoelectric and optical properties of a AgCd{sub 2-x}Mn{sub x}GaSe{sub 4} alloy with a Mn {yields} Cd isovalent substitution. The positions of the photoconductivity and photoluminescence peaks are determined, and the band gap of the alloy is estimated, based on compositional analysis. The influence of technological defects on specific features of the alloy's photoelectric and optical properties is analyzed. It is established that the centers controlling the alloy crystals' photosensitivity are cation vacancies. The photoluminescence centers responsible for emission at awavelengths from 0.77 to 0.88 {mu}m (dependent on the relation between components in the alloy) are defect complexes consisting of cation and anion vacancies. A physically consistent model is proposed to interpret the effects observed in the alloy.

  15. Photocatalytic performance of the SiO2 sphere/ n-type TiO2/ p-type CuBiS2 composite catalysts coated with different contents of Ag nanoparticles under ultraviolet and visible light irradiations

    NASA Astrophysics Data System (ADS)

    Abdullah, Hairus; Kuo, Dong-Hau

    2016-08-01

    Photocatalytic performance of the SiO2 sphere/ n-type TiO2/ p-type CuBiS2 composite catalysts with different contents of silver nanoparticles (abbreviated as SiO2/ n-TiO2/ p-CuBiS2/Ag) toward the photodegradation of Acid Black 1 ( AB 1) dye under ultraviolet (UV) and visible light was investigated. The composite catalyst spheres were analyzed their crystal structure, microstructure, optical absorbance capabilities, and photodegradation capabilities of AB 1 dye. The best photodegradation performances of the 20 mg composite powder with only ~5 mg photoactive catalysts showed the degradation of AB 1 dye in 5 min under UV and 60 min under visible light irradiations. The concept of composite catalyst with numerous nano p- n diodes and its photodegradation mechanism were proposed.

  16. Transport critical current density of (Bi1.6Pb0.4)Sr2Ca2Cu3O10/Ag superconductor tapes with addition of nanosized CoFe2O4

    NASA Astrophysics Data System (ADS)

    Hafiz, M.; Abd-Shukor, R.

    2015-09-01

    The effect of nanosized CoFe2O4 (60 nm) addition on the transport critical current density, J c, of (Bi1.6Pb0.4)Sr2Ca2Cu3O10(CoFe2O4) x ( x = 0-0.05 wt%) superconductor prepared by the co-precipitation method was investigated. The optimal J c (measured using the four-point probe method) was observed in the x = 0.01 wt% pellets. Using this optimal wt%, Ag-sheathed (Bi1.6Pb0.4)Sr2Ca2Cu3O10(CoFe2O4)0.01 superconductor tapes were fabricated using the powder-in-tube method. The tapes were sintered for 50 and 100 h at 845 °C. The phase and microstructure of the samples were determined using the powder X-ray diffraction method and scanning electron microscopy, respectively. The temperature dependence of J c for the tapes in various applied magnetic fields was also measured. J c of (Bi1.6Pb0.4)Sr2Ca2Cu3O10(CoFe2O4)0.01/Ag tapes sintered for 100 h was 22,420 A/cm2 at 30 K. The non-added tapes sintered for 100 h showed a much lower J c (8280 A/cm2 at 30 K). This study showed that addition of CoFe2O4 nanoparticles enhanced the transport critical current density in the (Bi1.6Pb0.4)Sr2Ca2Cu3O10 superconductor tapes. This result is consistent with the previous calculations on frozen flux superconductor in a nanomagnet-superconductor hybrid system.

  17. New experiments elucidating the current limiting mechanisms of Ag-sheathed (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} tapes.

    SciTech Connect

    Anderson, J.W.; Babcock, S.E.; Cai, X.Y.; Dorris, S.E.; Feldmann, M.; Jiang, J.; Larbalestier, D.C.; Li, Q.; Parrell, J.A.; Parrella, R.; Polak, M.; Polyanskii, A.; Riley, G.N. Jr.; Rupich, M.; Wu, Y.

    1999-01-15

    Multiple current limiting mechanisms exist from the nanometer to millimeter scale in Ag-sheathed (Bi,Pb)-2223 tapes. Recent studies of the zero-field critical current density (J{sub c} (0T, 77K)), the irreversibility field (H*) and the crack microstructure elucidate these properties. We show that H*(77K) can vary significantly over the range {approximately}120-260 mT, independently of J{sub c} (0T, 77K). Cracks, actual or incipient, exist on the sub to several hundred micron scale. Surface magneto optical imaging of whole tapes, correlated to subsequent ultrasonic fracture analysis of. the bare 2223 filaments extracted by dissolving away the Ag shows that even composites having J{sub c} (0T, 77K) values of 60 kA/cm{sup 2} exhibit strong signs of unhealed rolling damage. These combined studies show that today's very best 2223 tapes are still far from full optimization.

  18. The structural properties of CdO-Bi 2 O 3 borophosphate glass system containing Fe 2 O 3 and its role in attenuating neutrons and gamma rays

    NASA Astrophysics Data System (ADS)

    Saudi, H. A.; Mostafa, A. G.; Sheta, N.; El Kameesy, S. U.; Sallam, H. A.

    2011-11-01

    A glass system with chemical formula xBi 2O 3-(30- x)CdO-10B 2O 3-20Fe 2O 3-40P 2O 5 (0≤ x≤30) wt% is prepared to be used as radiation shield. The mass attenuation coefficient and half value layer of the glass system to gamma rays have been measured experimentally and compared with those determined from theoretical calculations using the mixture rule of WinXCom program. A database of effective mass removal cross-sections for fast neutrons is also introduced in this work. The obtained results of this study are correlated to the structural properties of these glasses obtained from their IR spectra and the influence of gamma and neutrons irradiation on these structural properties.

  19. Electrical and thermal properties of a carbon nanotube/polycrystalline BiFeO3/Pt photovoltaic heterojunction with CdSe quantum dots sensitization.

    PubMed

    Zang, Yongyuan; Xie, Dan; Chen, Yu; Wu, Xiao; Ren, Tianling; Wei, Jinquan; Zhu, Hongwei; Plant, David

    2012-04-28

    Electrical and thermal properties of a carbon nanotube (CNT)/multiferroic BiFeO(3) (BFO)/Pt photovoltaic heterojunction are investigated for the first time. Enhanced photovoltaic properties (J(sc)≈ 2.1 μA cm(-2) and V(oc)≈ 0.47 V), as compared to the traditional polycrystalline BFO with indium tin oxide (ITO) as the top electrode, are observed due to the unique properties of CNT. An equivalent electrical and thermal model is constructed based on the energy band diagram of the CNT/BFO/Pt heterojunction for the first time and the carriers' transportation behavior is depicted theoretically. The influence of CdSe quantum dots (QDs) sensitization on the photovoltaic properties is presented, and a clear improvement of ~4 fold in photocurrent density is observed. PMID:22456599

  20. Electrical and thermal properties of a carbon nanotube/polycrystalline BiFeO3/Pt photovoltaic heterojunction with CdSe quantum dots sensitization

    NASA Astrophysics Data System (ADS)

    Zang, Yongyuan; Xie, Dan; Chen, Yu; Wu, Xiao; Ren, Tianling; Wei, Jinquan; Zhu, Hongwei; Plant, David

    2012-04-01

    Electrical and thermal properties of a carbon nanotube (CNT)/multiferroic BiFeO3 (BFO)/Pt photovoltaic heterojunction are investigated for the first time. Enhanced photovoltaic properties (Jsc ~ 2.1 μA cm-2 and Voc ~ 0.47 V), as compared to the traditional polycrystalline BFO with indium tin oxide (ITO) as the top electrode, are observed due to the unique properties of CNT. An equivalent electrical and thermal model is constructed based on the energy band diagram of the CNT/BFO/Pt heterojunction for the first time and the carriers' transportation behavior is depicted theoretically. The influence of CdSe quantum dots (QDs) sensitization on the photovoltaic properties is presented, and a clear improvement of ~4 fold in photocurrent density is observed.

  1. Influence of metal (Cd and Zn) waterborne exposure on radionuclide (134Cs, 110Ag, and 57Co) bioaccumulation by rainbow trout (Oncorhynchus mykiss): a field and laboratory study.

    PubMed

    Ausseil, Olivier; Adam, Christelle; Garnier-Laplace, Jacqueline; Baudin, Jean-Pierre; Casellas, Claude; Porcher, Jean-Marc

    2002-03-01

    Field and laboratory experiments were carried out to assess the influence of Cd and Zn on the contamination levels of 110Ag, 57Co, and 134Cs in rainbow trout. During a four-week prior exposure phase, two fish groups were held in tanks in the Lot River (France) at a reference (<0.05 microg Cd/L and 68 microg Zn/L) and at a polluted site (1.5 microg Cd/L and 152 microg Zn/L). During a subsequent phase, organisms were brought back to the laboratory, where the radionuclide accumulation and depuration were studied for 14 and 7 d, respectively. During this second phase, the water used in the experiments was brought back from the two sites on the Lot River in order to work under the same chemical conditions. The potential effect of chronic exposure to stable metals on several biomarkers has been explored: Plasma analysis indicated the disruption of certain variables linked to the energetic metabolism and to the maintenance of the ionic balance. In contrast, no significant disruption of the measured enzyme activities was observed. With regard to the bioaccumulation of radionuclides, concentrations in fish exposed to metals are much lower than those in fish from the control group. Various hypotheses are proposed to link fish metabolic profiles due to metal exposure to the radiocontamination of organisms. PMID:11878476

  2. FAS -670 A/G polymorphism may be associated with the depletion of CD4(+) T lymphocytes in HIV-1 infection.

    PubMed

    Hermes, Renata Bezerra; Santana, Bárbara Brasil; Lima, Sandra Souza; Neris Martins Feitosa, Rosimar; de Oliveira Guimarães Ishak, Marluísa; Ishak, Ricardo; Vallinoto, Antonio Carlos Rosário

    2015-10-01

    In this study, the polymorphisms in the FAS and FASL genes was investigated in a sample of 198 HIV-1-seropositive individuals and 191 seronegative controls to evaluate a possible association between polymorphisms and the infection. The identification of the A and G alleles of the FAS -670 polymorphism was accomplished through polymerase chain reaction assays followed by digestion with the restriction enzyme MvaI. The identification of the A and G alleles of the FAS -124 polymorphism and the T and delT alleles of the FAS -169 polymorphism were performed using the amplification-created restriction site method followed by restriction fragment length polymorphism reactions. The comparative analysis of allelic and genotypic frequencies between the groups did not reveal any significant differences. However, the quantitative analysis of CD4(+) T lymphocytes suggests that the G allele of the FAS -670 A/G polymorphism can be a protective factor against the depletion of these cells in the course of an HIV-1 infection. Polymorphisms in the FAS and FASL genes were not associated with the number of CD8(+) T lymphocytes or the plasma viral load. Our findings suggest that the FAS -670 polymorphism may be associated with apoptosis of CD4(+) T lymphocytes after infection by HIV-1. PMID:26429326

  3. Flowing Liquid Anode Atmospheric Pressure Glow Discharge as an Excitation Source for Optical Emission Spectrometry with the Improved Detectability of Ag, Cd, Hg, Pb, Tl, and Zn.

    PubMed

    Greda, Krzysztof; Swiderski, Krzysztof; Jamroz, Piotr; Pohl, Pawel

    2016-09-01

    A novel atmospheric pressure glow discharge generated in contact with a flowing liquid anode (FLA-APGD) was developed as the efficient excitation source for the optical emission spectrometry (OES) detection. Differences in the appearance and the electrical characteristic of the FLA-APGD and a conventional system operated with a flowing liquid cathode (FLC-APGD) were studied in detail and discussed. Under the optimal operating conditions for the FLA-APGD, the emission from the analytes (Ag, Cd, Hg, Pb, Tl, and Zn) was from 20 to 120 times higher as compared to the FLC-APGD. Limits of detections (LODs) established with a novel FLA-APGD system were on average 20 times better than those obtained for the FLC-APGD. A further improvement of the LODs was achieved by reducing the background shift interferences and, as a result, the LODs for Ag, Cd, Hg, Pb, Tl, and Zn were 0.004, 0.040, 0.70, 1.7, 0.035, and 0.45 μg L(-1), respectively. The precision of the FLA-APGD-OES method was evaluated to be within 2-5% (as the relative standard deviation of the repeated measurements). The method found its application in the determination of the content of Ag, Cd, Hg, Pb, Tl, and Zn in a certified reference material (CRM) of Lobster hepatopancreas (TORT-2), four brass samples as well as mineral water and tea leaves samples spiked with the analytes. In the case of brass samples, a reference method, i.e., inductively coupled plasma optical emission spectrometry (ICP-OES) was used. A good agreement between the results obtained with FLA-APGD-OES and the certified values for the CRM TORT-2 as well as the reference values obtained with ICP-OES for the brass samples was revealed, indicating the good accuracy of the proposed method. The recoveries obtained for the spiked samples of mineral water and tea leaves were within the range of 97.5-102%. PMID:27476678

  4. Sonophotocatalytic degradation of trypan blue and vesuvine dyes in the presence of blue light active photocatalyst of Ag3PO4/Bi2S3-HKUST-1-MOF: Central composite optimization and synergistic effect study.

    PubMed

    Mosleh, S; Rahimi, M R; Ghaedi, M; Dashtian, K

    2016-09-01

    An efficient simultaneous sonophotocatalytic degradation of trypan blue (TB) and vesuvine (VS) using Ag3PO4/Bi2S3-HKUST-1-MOF as a novel visible light active photocatalyst was carried out successfully in a continuous flow-loop reactor equipped to blue LED light. Ag3PO4/Bi2S3-HKUST-1-MOF with activation ability under blue light illumination was synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), photoluminescence (PL) and diffuse reflectance spectra (DRS). The effect of operational parameters such as the initial TB and VS concentration (5-45mg/L), flow rate (30-110mL/min), irradiation and sonication time (10-30min), pH (3-11) and photocatalyst dosage (0.15-0.35g/L) has been investigated and optimized using central composite design (CCD) combined with desirability function (DF). Maximum sonophotodegradation percentage (98.44% and 99.36% for TB and VS, respectively) was found at optimum condition set as: 25mg/L of each dye, 70mL/min of solution flow rate, 25min of irradiation and sonication time, pH 6 and 0.25g/L of photocatalyst dosage. At optimum conditions, synergistic index value was obtained 2.53 that indicated the hybrid systems including ultrasound irradiation and photocatalysis have higher efficiency compared with sum of the individual processes. PMID:27150785

  5. Benefits of Carrier-Pocket Anisotropy to Thermoelectric Performance: The Case of p -Type AgBiSe2

    SciTech Connect

    Parker, David S.; May, Andrew F.; Singh, David J.

    2015-06-05

    Here we study theoretically the effects of anisotropy on the thermoelectric performance of p-type AgBiSe2. We present an apparent realization of the thermoelectric benefits of one-dimensional plate-like carrier pocket anisotropy in the valence band of this material. Based on first principles calculations we find a substantial anisotropy in the electronic structure, likely favorable for thermoelectric performance, in the valence bands of the hexagonal phase of the silver chalcogenide thermoelectric AgBiSe2, while the conduction bands are more isotropic, and in our experiments do not attain high performance. AgBiSe2 has already exhibited a ZT value of 1.5 in a high-temperature disordered fcc phase, but room-temperature performance has not been demonstrated. We develop a theory for the ability of anisotropy to decouple the density-of-states and conductivity effective masses, pointing out the influence of this effect in the high performance thermoelectrics Bi2Te3 and PbTe. From our first principles and Boltzmann transport calculations we find that p-type AgBiSe2 has substantial promise as a room temperature thermoelectric, and estimate its performance.

  6. A comparative computational study on hydrogen adsorption on the Ag(+), Cu(+), Mg(2+), Cd(2+), and Zn(2+) cationic sites in zeolites.

    PubMed

    Kozyra, Paweł; Piskorz, Witold

    2016-05-14

    In this article the interaction between H2 and Ag(+), Cu(+), Mg(2+), Cd(2+), and Zn(2+) cations in cluster models of several sizes has been studied computationally. Depending on the changes imposed by the adsorption process on the H2 molecule the activation can vary in a wide range - from only slight weakening of the H-H bond to complete dissociation of the H2 molecule. The NOCV (Natural Orbitals for Chemical Valence) analysis allowed for decomposition of the electron density distortion into contributions easier for interpretation. Three essential factors have been identified (i-iii). In the case of bare cations the main contribution is a donation from σH2 to the cation (i). When a zeolite framework surrounding the cation is introduced, it hinders σ-donation and enhances π-backdonation from the cation to the antibonding orbital of the molecule (ii). For Cu(i) and Ag(i) sites π-backdonation becomes dominant, while for Mg(ii), Cd(ii), and Zn(ii) cations, the σ-donation, albeit diminished, still remains a dominant contribution. Calculations showed that the localization and coordination of Zn(ii) have crucial influence on its interaction with H2. We identified a Zn(2+) position at which the H2 molecule dissociates - here the interaction between H2 and oxygen framework (iii) plays a crucial role. Based on the calculations the mechanism of H2 transformation has been proposed. Upon heterolytic dissociation of H2 the Zn(0) moiety and two OH groups can be formed. Eventually, in two elementary steps, the H2 molecule can be restored. In this case, the ability of the site to activate/dissociate hydrogen is caused by the low coordination number of the zinc cation and the geometry of the site which allows positively charged H2 to interact with framework oxygen what enhances the formation of OH and Z-O-(ZnH)(+) groups. PMID:27092373

  7. Fluorometric selective detection of fluoride ions in aqueous media using Ag doped CdS/ZnS core/shell nanoparticles.

    PubMed

    Boxi, Siddhartha Sankar; Paria, Santanu

    2016-01-14

    The presence of fluoride ions in drinking water plays an important role in human health. For that reason, maintaining the optimum concentration of fluoride ions in drinking water is essential, as both low and excess (above the permissible level) concentrations can cause different health problems, such as fluorosis, urolithiasis, kidney failure, cancer, and can even lead to death. So, development of a simple and low cost method for the detection of fluoride ions in water is highly desirable. In this study, a fluorometric method based on Ag-CdS/Ag-ZnS core/shell nanoparticles is developed for fluoride ion detection. The method was tested in aqueous solution at different pH values. The selectivity and sensitivity of the fluorescence probe was checked in the presence of other anions (Cl(-), Br(-), I(-), NO3(-) SO4(2-), HCO3(-), HPO4(2-), CH3COO(-), and H2PO4(-)) and found there is no significant interference of these associated ions. The fluoride ion concentration was varied in the range 190-22 800 μg L(-1) and a lower detection limit was obtained as 99.7 μg L(-1). PMID:26645767

  8. Photocatalytic removal of M(2+) (Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) over new catalyst CuCrO(2).

    PubMed

    Ketir, W; Bouguelia, A; Trari, M

    2008-10-30

    The metal ions M(2+) (Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) are potentially toxic. Their electro deposition has been carried out in aqueous air-equilibrated CuCrO(2) suspension upon visible illumination. The delafossite CuCrO(2) is p-type semiconductor characterized by a low band gap (1.28 eV) and a long-term chemical stability. The corrosion rate is found to be 10(-2) micromol m(-2)month(-1) in aqua regia. The oxide has been elaborated through nitrate route where the specific surface area is increased via the surface/bulk ratio. A correlation exists between the dark M(2+) adsorption, the redox potential of M(2+/0) couple and the conduction band of CuCrO(2) positioned at -1.06 V(SCE). Ag(+) cannot be photoreduced because of its positive potential located far above the valence band. By contrast, Zn(2+) is efficiently deposited due to the large driving force at the interface. The improved photoactivity of copper with a deposition percentage (90%) is attributed to the strong dark adsorption onto the surface catalyst. The results indicate a competitive effect with the water reduction; it has been observed that the M(2+) deposition goes parallel with the hydrogen evolution. Such behavior is attributed to the low H(2) over voltage when ultra fine aggregate of M islands are photodeposited onto CuCrO(2) substrate. PMID:18384943

  9. On the influence of magnetic field processing on the texture, phase assemblage and properties of low aspect ratio Bi2 Sr2 CaCu2 Ox /AgMg wire

    NASA Astrophysics Data System (ADS)

    Liu, Xiaotao; Schwartz, Justin

    2009-01-01

    Bi2 Sr2 CaCu2 Ox /AgMg conductors are potentially important for many applications up to 20 K, including magnets for cryogen-free magnetic resonance imaging and high field nuclear magnetic resonance research. One promising approach to increased critical current density is partial-melt processing in the presence of a magnetic field which has been shown to enhance c-axis texturing of wide, thin tape conductors. Here, we report on low aspect ratio rectangular conductors processed in an 8 T magnetic field. The magnetic field is applied during different stages of the heat treatment process. The conductors are electrically characterized using four-point critical current measurements as a function of magnetic field and magnetic field orientation relative to the conductor. The superconductive transition and magnetization hysteresis are measured using a SQUID magnetometer. The microstructures are characterized using scanning electron microscopy and energy dispersive spectroscopy and analyzed using digital image processing. It is found that the presence of a magnetic field during split melt processing enhances the electrical transport and magnetic behavior, but that the anisotropy is not consistently affected. The magnetic field also affects development of interfilamentary Bi2212 bridges, and that this depends on the initial shape of the Bi2212 filament. At least two behaviors are identified; one impacts the oxide phase assemblage and the other impacts textured growth.

  10. Modeling effects of gas bubbles on the mechanical behaviors of Ag/Bi-2212 round wires using a double cantilever beam bridge model

    NASA Astrophysics Data System (ADS)

    Lu, Yurong; Wang, Zhongtong; Yong, Huadong; Zhou, Youhe

    2016-07-01

    Due to the larger current-carrying property, Bi2Sr2CaCu2Ox (Bi2212) superconductors have a great potential application in high field magnet. Bi2212 superconducting material can be fabricated as an isotropic round wire. However, there is 30% void space in the wire, such as gas bubbles. The void space has a larger influence on the property of the wire. In this paper, we will study the effect of gas bubble on the fracture behavior. Based on the double cantilever beam model and critical state theory, the mechanical behavior of Bi2212 wire is studied for decreasing field. Two different damage mechanisms are discussed using the strain energy release rate and strain of bridge. The results show that the large gas bubble can increase the strain of bridge. The central filaments with gas bubble are easier to be damaged than the edge filaments with gas bubble.

  11. Crystallization kinetics, optical and dielectric properties of Li2OṡCdOṡBi2O3ṡSiO2 glasses

    NASA Astrophysics Data System (ADS)

    Rani, Saroj; Sanghi, Sujata; Ahlawat, Neetu; Agarwal, Ashish

    2015-10-01

    Crystallization kinetics, optical absorption and electrical behavior of lithium cadmium silicate glasses with different amount of bismuth oxide were investigated using non-isothermal crystallization approach, UV-VIS-NIR spectroscopy and impedance spectroscopy, respectively. These glasses were synthesized by normal melt quenching technique. Variation in physical properties, viz. density, molar volume with Bi2O3:SiO2 ratio were related to the structural changes occurring in the glasses. The glass transition temperature (Tg), crystalline peak temperature (Tp) and melting temperature (Tm) of these glasses were determined using differential scanning calorimeter at various heating rates. The dependence of Tg and Tp on heating rate has been used for the determination of the activation energy of glass transition and crystallization. Thermal stability parameters have revealed high stability of the glass prepared with 40 mol% of Bi2O3 content. The crystallization kinetics for the glasses was studied by using the Kissinger and modified Ozawa equations. Appearance of a sharp cut-off and a wide and reasonable transmission in VIS-NIR region makes these glasses suitable for IR transmission window. The cut-off wavelength, optical band gap and Urbach's energy have been analyzed and discussed in terms of changes in the glass structure. By analyzing the impedance spectra, the ac and dc conductivities, activation energy for dc conduction (Edc) and for relaxation (EM″) were calculated. The results obtained from dc conductivity confirm the network forming role of Cd2+ ion in the glasses. The scaling of the conductivity spectra has been used to interpret the temperature dependence of the relaxation dynamics. The observed conductivity spectra follows power law with exponent 's' which decreases with temperature and satisfies the correlated barrier hopping (CBH) model. The perfect overlying of normalized plots of electrical modulus on a single 'master curve' depicts temperature as well as

  12. Subcellular partitioning of non-essential trace metals (Ag, As, Cd, Ni, Pb, and Tl) in livers of American (Anguilla rostrata) and European (Anguilla anguilla) yellow eels.

    PubMed

    Rosabal, Maikel; Pierron, Fabien; Couture, Patrice; Baudrimont, Magalie; Hare, Landis; Campbell, Peter G C

    2015-03-01

    We determined the intracellular compartmentalization of the trace metals Ag, As, Cd, Ni, Pb, and Tl in the livers of yellow eels collected from the Saint Lawrence River system in Canada (Anguilla rostrata) and in the area of the Gironde estuary in France (Anguilla anguilla). Differential centrifugation, NaOH digestion and thermal shock were used to separate eel livers into putative "sensitive" fractions (heat-denatured proteins, mitochondria and microsomes+lysosomes) and detoxified metal fractions (heat-stable peptides/proteins and granules). The cytosolic heat-stable fraction (HSP) was consistently involved in the detoxification of all trace metals. In addition, granule-like structures played a complementary role in the detoxification of Ni, Pb, and Tl in both eel species. However, these detoxification mechanisms were not completely effective because increasing trace metal concentrations in whole livers were accompanied by significant increases in the concentrations of most trace metals in "sensitive" subcellular fractions, that is, mitochondria, heat-denatured cytosolic proteins and microsomes+lysosomes. Among these "sensitive" fractions, mitochondria were the major binding sites for As, Cd, Pb, and Tl. This accumulation of non-essential metals in "sensitive" fractions likely represents a health risk for eels inhabiting the Saint Lawrence and Gironde environments. PMID:25635611

  13. Atomic-level observation of Ag-ion hopping motion in AgI

    NASA Astrophysics Data System (ADS)

    Sato, W.; Komatsuda, S.; Mizuuchi, R.; Irioka, N.; Kawata, S.; Ohkubo, Y.

    2015-04-01

    Applicability of the 111mCd(→111Cd) and 111In(→111Cd) probes to the study of dynamics in polycrystalline silver iodide (AgI) was examined by means of the time-differential perturbed angular correlation technique. It was found that the 111mCd(→111Cd) probe occupies a unique site in γ-AgI and exhibits nuclear relaxation caused by dynamic perturbation arising from Ag + hopping motion in α-AgI; while the residential sites of 111In(→111Cd) vary, suggesting that 111In ions can not settle themselves in a fixed site in the AgI crystal structure. We here demonstrate that 111mCd(→111Cd) can be a potential nucleus to probe the Ag +-ion dynamic motion in α-AgI.

  14. Effects of temperature, silicate melt composition, and oxygen fugacity on the partitioning of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide phases and silicate melt

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Audétat, Andreas

    2015-08-01

    In order to assess the role of sulfide in controlling the ore metal budgets and fractionation during magmatic genesis and differentiation, the partition coefficients (D) of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide liquid (SL), monosulfide solid solution (MSS), and basaltic to rhyolitic melts (SM) were determined at 900-1200 °C, 0.5-1.5 GPa, and oxygen fugacity (fO2) ranging from ∼FMQ-2 to FMQ+3, in a piston-cylinder apparatus. The DSL/SM values range from 0.4 to 2 for V, 0.5 to 3 for Mn, 80 to 580 for Co, 2300 to 18,000 for Ni, 800 to 4600 for Cu, 1 to 11 for Zn, 20 to 180 for As, 4 to 230 for Mo, 450 to 1600 for Ag, 5 to 24 for Sn, 10 to 80 for Sb, 0.03 to 0.16 for W, 2000 to 29,000 for Au, 24 to 170 for Pb, and 830 to 11,000 for Bi; whereas the DMSS/SM values range from 0.04 to 10 for V, 0.5 to 10 for Mn, 70 to 2500 for Co, 650 to 18,000 for Ni, 280 to 42,000 for Cu, 0.1 to 80 for Zn, 0.2 to 30 for As, 1 to 820 for Mo, 20 to 500 for Ag, 0.2 to 220 for Sn, 0.1 to 40 for Sb, 0.01 to 24 for W, 10 to 2000 for Au, 0.03 to 6 for Pb, and 1 to 350 for Bi. Both DMSS/SM and DSL/SM values generally increase with decreasing temperature or decreasing FeOtot content in silicate melt, except for Mo, DMSS/SM and DSL/SM of which show a clear decrease with decreasing temperature. At given temperature and FeOtot content, high oxygen fugacity appears to lead to a significant decrease in DMSS/SM of Au, Bi, Mo, and potentially As. The partitioning data obtained experimentally in this study and previous studies were fitted to an empirical equation that expresses the DMSS/SM and/or DSL/SM of a given element as a function of temperature, oxygen fugacity, and FeOtot content of the silicate melt: log (DSL/SMorDMSS/SM = d + a · 10, 000 / T + b · (ΔFMQ) + c · log (FeOmelt) in which T is temperature in K, FeOmelt denotes wt% FeOtot in silicate melt, and ΔFMQ denotes log fO2 relative to the fayalite-magnetite-quartz (FMQ) oxygen buffer. The

  15. Observation of surface plasmon resonance of silver particles and enhanced third-order optical nonlinearities in AgCl doped Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3}-SiO{sub 2} ternary glasses

    SciTech Connect

    Xu, Tiefeng; Chen, Feifei; Shen, Xiang; Dai, Shixun; Nie, Qiuhua; Wang, Xunsi

    2010-10-15

    Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3}-SiO{sub 2} ternary glasses embedded with Ag nanoparticles were prepared by introducing AgCl into the bismuthate glasses using conventional melt quenching method and characterized by several experimental techniques. Scanning electron microscopic studies indicated the formation of Ag contained nanoclusters which crack and become regular with increase of AgCl content in these composites. Optical absorption spectra of the nanocomposites showed the presence of absorption band of surface plasmon resonance (SPR) due to Ag nanoparticles at {approx}600 nm. Z-scan measurement with femtosecond laser was used to investigate third-order optical nonlinearities of the nanocomposites. The results show that the nonlinear refraction {gamma} was dramatically increased up to 30 times by the appearance of Ag nanoparticles when excited within its SPR region, while nonlinear absorption due to two-photon absorption exhibited opposite tendency or even saturated behavior. The calculation of figure of merit suggests that the Ag particle embedded Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3}-SiO{sub 2} glass composites are promising candidates for optoelectronic devices.

  16. The effect of a large amount of Ag introduced into the Bi1.84Pb0.34Sr1.91Ca2.03Cu3.06O10+δ (110 K phase) high-Tc superconductor

    NASA Astrophysics Data System (ADS)

    Song, Ki Young; Lee, Min Soo

    2006-12-01

    We synthesized a 50 wt% Ag-doped Bi-110 K phase high-Tc superconductor by a solid state reaction method. The nominal composition of the 110 K phase was Bi1.84Pb0.34Sr1.91Ca2.03Cu3.06O10+δ, which was prepared from powders of Bi2O3 (99.99%), PbO (99.99%), SrCO3 (99.99%), CaCO3 (99.99%) and CuO (99.99%). The synthesized Bi single-phase high-Tc superconductor was pulverized and mixed with Ag powder amounting to 50 wt%. Then the 50 wt% Ag-doped composition was sintered between 830 and 850 °C, and the superconducting properties, such as the structural characteristics, critical temperature (Tc), grain size and the mapping image of the surface were investigated. The critical temperature was about 99 K, independent of the sintering temperature in the range from 830 to 850 °C, and most superconducting grains were sintered in the layer near the surface, while Ag particles were aggregated and sintered as clusters and mostly distributed over an inside layer during the sintering process.

  17. RAPID COMMUNICATION: Radio frequency response of Ag-sheathed (Bi, Pb)2Sr2Ca2Cu3O10+x superconducting tapes

    NASA Astrophysics Data System (ADS)

    Grasso, G.; Malagoli, A.; Scati, N.; Guasconi, P.; Roncallo, S.; Siri, A. S.

    2000-10-01

    The response of long (Bi,Pb)2Sr2Ca2Cu3O10 conductors fabricated by the oxide-powder-in-tube method to a radio frequency excitation was investigated while employed as the inductive part of large L-C resonating circuits. After removal of the outer silver sheath, superconducting devices cooled down to 77 K showed superior properties compared to equivalent non-superconducting circuits: Bi-based resonators, conceived for a working frequency in the range between 5 and 17 MHz, presented an improvement of the quality factor by a factor of 20. This result opens new perspectives for the application of Bi-based superconducting materials in the detection of a weak radio frequency signal, as in magnetic resonance imaging.

  18. Crystal structure and microwave dielectric behaviors of ultra-low-temperature fired x(Ag(0.5)Bi(0.5))MoO₄-(1 - x)BiVO₄ (0.0 ≤ x ≤ 1.0) solid solution with scheelite structure.

    PubMed

    Zhou, Di; Pang, Li-Xia; Qi, Ze-Ming

    2014-09-01

    x(Ag(0.5)Bi(0.5))MoO4-(1 - x)BiVO4 (0.0 ≤ x ≤ 1.0) ceramics were prepared by using the solid-state reaction technique. Ceramics with x < 0.10 had a monoclinic scheelite structure, while those with ≥0.10 were tetragonal scheelite solid solutions. This indicates that the phase transformation temperature of BiVO4 was lowered through the formation of a solid solution. The thermal expansion data of the x = 0.08 sample showed that the thermal expansion coefficient was increased suddenly from +8 to +15 ppm/°C at about 60.6 °C due to the phase transition. Similarly, a maximum value of microwave dielectric permittivity was revealed at about 65 °C for the x = 0.08 sample. All of the ceramics could be well sintered below 700 °C. Good microwave dielectric behaviors, with relative permittivity >75 and Q(f) > 9000 GHz, were obtained in ceramics with compositions near x = 0.10. Both the THz data and the infrared spectra were used to study the intrinsic dielectric behavior of the materials at microwave frequencies. PMID:25105210

  19. Synchrotron x-ray scattering measurements of bulk structural properties in superconducting (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}{endash}Ag tapes

    SciTech Connect

    Thurston, T.R.; Wildgruber, U.; Jisrawi, N.; Haldar, P.; Suenaga, M.; Wang, Y.L.

    1996-03-01

    The structural properties of superconducting (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}{endash}Ag (2223) tapes have been measured using synchrotron x-ray scattering techniques. The x-ray photon energy was tuned just below the silver {ital K} absorption edge so the penetration depth was large, which allowed the measurements to be performed in a transmission geometry without removing the silver cladding. Analysis of the peaks in 2{theta} scans indicates that residual (Bi,Pb){sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (2212) superconductor starting material is present in all samples studied. The amount of 2212 varied widely among the tapes, and was not homogeneous along the length of each individual tape. Residual 2212 content increased near the ends of most samples, suggesting that 2223 phase development is sensitive to whether the superconducting material is encased in silver or not. The bulk {ital c}-axis alignment was measured in {approximately}100 mono- and multifilament samples, and correlations between {ital c}-axis alignment and current carrying capacity at 77 K were found. Multifilament samples generally had better alignment than monofilament samples. The {ital c}-axis alignment along the length of the tapes was uniform, and the superconducting material within {approximately}1 {mu}m of the Ag was better textured than the bulk of the sample. Intermediate pressings were directly shown to have an adverse affect on {ital c}-axis alignment. Finally, the evolution of texture and phase development was examined in a series of samples annealed for varying times. The 2212 starting material acquired the final {ital c}-axis alignment state after brief heating times, and only after much longer heating times did the 2212 transform into the 2223 phase. These results and their implications for improving processing procedures are discussed. {copyright} {ital 1996 American Institute of Physics.}

  20. Screening on binary Zr-1X (X = Ti, Nb, Mo, Cu, Au, Pd, Ag, Ru, Hf and Bi) alloys with good in vitro cytocompatibility and magnetic resonance imaging compatibility.

    PubMed

    Zhou, F Y; Qiu, K J; Li, H F; Huang, T; Wang, B L; Li, L; Zheng, Y F

    2013-12-01

    In this study, the microstructures, mechanical properties, corrosion behaviors, in vitro cytocompatibility and magnetic susceptibility of Zr-1X alloys with various alloying elements, including Ti, Nb, Mo, Cu, Au, Pd, Ag, Ru, Hf and Bi, were systematically investigated to explore their potential use in biomedical applications. The experimental results indicated that annealed Zr-1X alloys consisted entirely or primarily of α phase. The alloying elements significantly increased the strength and hardness of pure Zr and had a relatively slight influence on elastic modulus. Ru was the most effective enhancing element and Zr-1Ru alloy had the largest elongation. The results of electrochemical corrosion indicated that adding various elements to Zr improved its corrosion resistance, as indicated by the reduced corrosion current density. The extracts of the studied Zr-1X alloys produced no significant deleterious effects on osteoblast-like cells (MG 63), indicating good in vitro cytocompatibility. All except for Zr-1Ag alloy showed decreased magnetic susceptibility compared to pure Zr, and Zr-1Ru alloy had the lowest magnetic susceptibility value, being comparable to that of α' phase Zr-Mo alloy and Zr-Nb alloy and far lower than that of Co-Cr alloy and Ti-6Al-4V alloy. Among the experimental Zr-1X alloys, Zr-1Ru alloy possessing high strength coupled with good ductility, good in vitro cytocompatibility and low magnetic susceptibility may be a good candidate alloy for medical devices within a magnetic resonance imaging environment. PMID:23928334

  1. 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.

  2. Direct detection of Pb in urine and Cd, Pb, Cu, and Ag in natural waters using electrochemical sensors immobilized with DMSA functionalized magnetic nanoparticles

    SciTech Connect

    Yantasee, Wassana; Hongsirikarn, Kitiya; Warner, Cynthia L.; Choi, Daiwon; Sangvanich, Thanapon; Toloczko, Mychailo B.; Warner, Marvin G.; Fryxell, Glen E.; Addleman, Raymond S.; Timchalk, Chuck

    2008-03-01

    Urine is universally recognized as one of the best non-invasive matrices for biomonitoring exposure to a broad range of xenobiotics including toxic metals. For direct, simple, and field-deployable monitoring of urinary Pb, electrochemical sensors employing superparamagnetic iron oxide (Fe3O4) nanoparticles with a surface functionalization of dimercaptosuccinic acid (DMSA) has been developed. The metal detection involves rapid collection of dispersed metal-bound nanoparticles from a sample solution at a magnetic or electromagnetic electrode, followed by the stripping voltammetry of the metal in acidic medium. The sensors were evaluated as a function of solution pH, the binding affinity of Pb to DMSA-Fe3O4, the ratio of nanoparticles per sample volume, preconcentration time, and Pb concentrations. The effect of binding competitions between the DMSA-Fe3O4 and urine constituents for Pb on the sensor responses was studied. After 90s of preconcentration in samples containing 25 vol.% of rat urine and 0.1 g/L of DMSA-Fe3O4, the sensor could detect background level of Pb (< 1 ppb) and yielded linear responses from 0 to 50 ppb of Pb, excellent reproducibility (%R.S.D of 5.3 for seven measurements of 30 ppb Pb), and Pb concentrations comparable to those measured by ICP-MS. The sensor could also simultaneously detect background levels (< 1 ppb) of Cd, Pb, Cu, and Ag in river and seawater.

  3. Effects of increased pCO2 and temperature on trace element (Ag, Cd and Zn) bioaccumulation in the eggs of the common cuttlefish, Sepia officinalis

    NASA Astrophysics Data System (ADS)

    Lacoue-Labarthe, T.; Martin, S.; Oberhänsli, F.; Teyssié, J.-L.; Markich, S.; Jeffree, R.; Bustamante, P.

    2009-05-01

    Cephalopods play a key role in many marine trophic networks and constitute alternative fisheries resources, especially given the ongoing decline in finfish stocks. Along the European coast, the eggs of the cuttlefish Sepia officinalis are characterized by an increasing permeability of the eggshell during development, which leads to selective accumulation of essential and non-essential elements in the embryo. Temperature and pH are two critical factors that affect the metabolism of marine organisms in the coastal shallow waters. In this study, we are testing the effects of pH and temperature through a crossed (3×2) laboratory experiment. Seawater pH showed a strong effect on the egg weight and non-significant impact on the hatchlings weight at the end of development implying egg swelling process and embryo growth disturbances. The lower pH of incubation seawater of eggs, the more the hatchlings accumulated 110m Ag in their tissues. The 109Cd CF decreased with increasing pH and 65Zn CF reached the maximal values pH 7.85, independent of temperature. Our results suggest that pH and temperature affected both the permeability properties of the eggshell and the embryo metabolism. To the best of our knowledge, this is one of the first studies on the ocean acidification and ocean warming consequences on the metal uptake in marine organisms, stimulating further interest to evaluate the likely ecotoxicological impact of the global change on the early-life stage of the cuttlefish.

  4. Ion conduction in the Ag{sub 2}HgI{sub 4}-Cu{sub 2}HgI{sub 4} systems doped with Cd{sup 2+}, K{sup +}, and Na{sup +}

    SciTech Connect

    Nair, S.M.; Yahya, A.I.; Ahmad, A.

    1996-03-01

    Ion conductivities of face centered cubic Ag{sub 2}HgI{sub 4}-Cu{sub 2}HgI{sub 4} systems doped with Cd{sup 2+}, K{sup +}, and Na{sup +} were measured. In 67 mol% Ag{sub 2}HgI{sub 4} solid solution doped with Cd{sup 2+} ions, the phase transition occurs at a lower temperature than in the parent compounds and the system shows higher conductivity. The increase in conductivity is discussed in terms of vacancies produced. K{sup +} doped Ag{sub 2}HgI{sub 4} exhibits higher conductivity prior to the phase transition, which is attributed to lattice loosening. A decrease in conductivity is observed above 140{degrees}C. This is interpreted in terms of anion framework collapse. Na{sup +} doped Ag{sub 2}HgI{sub 4} shows high conductivity for the high temperature phase because of the small size of Na{sup +} ions. The activation energy for ionic motion for all the samples is calculated from the graph of log({delta}T) versus 1/T.

  5. Microstructural characterization of Ag-sheathed Tl-Ba-Ca-Cu-O and Bi-Sr-Ca-Cu-O superconducting tapes by analytical electron microscopy

    SciTech Connect

    Hu, J.G.; Miller, D.J.; Goretta, K.C.; Poeppel, R.B.

    1992-09-01

    The microstructures of Tl(1223) and Pb-doped Bi(2223) silver tapes produced by the powder-in-tube (PM) method have been examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS). The Tl tapes annealed below the melting point exhibited fine grains and a high density of pores while tapes subjected to partial melting prior to solid state annealing were fully dense with large grains. However, these tapes also showed an increase in the size and density of impurity particles, particularly CaO and a Ba-Cu rich phase. Silver powders added to the precursors tended to promote the growth of Tl(1223) at lower temperatures but also interfered with the development of texture by providing nucleation sites of random orientations. In contrast, the Bi(2223) tape exhibited a high degree of texture and alignment. The incorporation of silver within the superconducting phase was found to be negligible for both the Tl(1223) and Bi(2223) tapes.

  6. Oxygen vacancies induced switchable and nonswitchable photovoltaic effects in Ag/Bi{sub 0.9}La{sub 0.1}FeO{sub 3} /La{sub 0.7}Sr{sub 0.3}MnO{sub 3} sandwiched capacitors

    SciTech Connect

    Gao, R. L. E-mail: jrsun@iphy.ac.cn; Yang, H. W.; Chen, Y. S.; Sun, J. R. E-mail: jrsun@iphy.ac.cn; Shen, B. G.; Zhao, Y. G.

    2014-01-20

    The short circuit photocurrent (I{sub sc}) was found to be strongly dependent on the oxygen vacancies (V{sub Os}) distribution in Ag/Bi{sub 0.9}La{sub 0.1}FeO{sub 3}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3} heterostructures. In order to manipulate the V{sub Os} accumulated at either the Ag/Bi{sub 0.9}La{sub 0.1}FeO{sub 3} or the Bi{sub 0.9}La{sub 0.1}FeO{sub 3}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3} interface by pulse voltages, switchable or nonswitchable photocurrent can be observed without or with changing the polarization direction. The sign of photocurrent could be independent of the direction of polarization when the variation of diffusion current and the modulation of the Schottky barrier at the Ag/Bi{sub 0.9}La{sub 0.1}FeO{sub 3} interface induced by oxygen vacancies are large enough to offset those induced by polarization. Our work provides deep insights into the nature of photovoltaic effects in ferroelectric films, and will facilitate the advanced design of switchable devices combining spintronic, electronic, and optical functionalities.

  7. Comparative study of A-site order in the lead-free bismuth titanates M{sub 1/2}Bi{sub 1/2}TiO{sub 3} (M=Li, Na, K, Rb, Cs, Ag, Tl) from first-principles

    SciTech Connect

    Gröting, Melanie Albe, Karsten

    2014-05-01

    We investigate the possibility of enhancing chemical order in the relaxor ferroelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3} upon substitution of Na{sup +} by other monovalent cations M{sup +} using total energy calculations based on density functional theory. All chemically available monovalent cations M{sup +}, which are Li, Na, Ag, K, Tl, Rb and Cs, are considered and an analysis of the structurally relaxed structures in terms of symmetry-adapted distortion modes is given in order to quantify the chemically induced structural distortions. We demonstrate that the replacement of Na{sup +} by other monovalent cations can hardly alter the tendency of chemical order with respect to Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}. Only Tl{sub 1/2}Bi{sub 1/2}TiO{sub 3} and Ag{sub 1/2}Bi{sub 1/2}TiO{sub 3} show enhanced tendency for chemical ordering. Both heavy metals behave similar to the light alkali metals in terms of structural relaxations and relative stabilities of the ordered configurations. Although a comparison of the Goldschmidt factors of components (M TiO{sub 3}){sup −} reveals for Tl a value above the upper stability limit for perovskites, the additional lone-pair effect of Tl{sup +} stabilizes the ordered structure. - Graphical abstract: Amplitudes of chemically induced distortion modes in different ordered perovskites M{sub 1/2}Bi{sub 1/2}TiO{sub 3} and visualisation of atomic displacements associated with distortion mode X{sup +}{sub 1} in the 001-ordered compounds Li{sub 1/2}Bi{sub 1/2}TiO{sub 3} and Cs{sub 1/2}Bi{sub 1/2}TiO{sub 3}. Due to a substantial size mismatch between bismuth (green) and caesium (dark blue), incorporation of the latter leads to enhanced displacements of oxygen atoms (red) and suppresses displacements of titanium (silver) as compared to lithium (light blue) or other smaller monovalent cations. - Highlights: • Lead-free A-site mixed bismuth titanates M{sub 1/2}Bi{sub 1/2}TiO{sub 3} are studied by first-principles calculations. • Investigation

  8. Effects of increased pCO2 and temperature on trace element (Ag, Cd and Zn) bioaccumulation in the eggs of the common cuttlefish, Sepia officinalis

    NASA Astrophysics Data System (ADS)

    Lacoue-Labarthe, T.; Martin, S.; Oberhänsli, F.; Teyssié, J.-L.; Markich, S.; Ross, J.; Bustamante, P.

    2009-11-01

    Cephalopods play a key role in many marine trophic networks and constitute alternative fisheries resources, especially given the ongoing decline in finfish stocks. Along the European coast, the eggs of the cuttlefish Sepia officinalis are characterized by an increasing permeability of the eggshell during development, which leads to selective accumulation of essential and non-essential elements in the embryo. Temperature and pH are two critical factors that affect the metabolism of marine organisms in the coastal shallow waters. In this study, we investigated the effects of pH and temperature through a crossed (3×2; pH 8.1 (pCO2, 400 ppm), 7.85 (900 ppm) and 7.6 (1400 ppm) at 16 and 19°C, respectively) laboratory experiment. Seawater pH showed a strong effect on the egg weight and non-significant impact on the weight of hatchlings at the end of development implying an egg swelling process and embryo growth disturbances. The lower the seawater pH, the more 110 mAg was accumulated in the tissues of hatchlings. The 109Cd concentration factor (CF) decreased with decreasing pH and 65Zn CF reached maximal values pH 7.85, independently of temperature. Our results suggest that pH and temperature affected both the permeability properties of the eggshell and embryonic metabolism. To the best of our knowledge, this is one of the first studies on the consequences of ocean acidification and ocean warming on metal uptake in marine organisms, and our results indicate the need to further evaluate the likely ecotoxicological impact of the global change on the early-life stages of the cuttlefish.

  9. The − 5 A/G single-nucleotide polymorphism in the core promoter region of MT2A and its effect on allele-specific gene expression and Cd, Zn and Cu levels in laryngeal cancer

    SciTech Connect

    Starska, Katarzyna; Krześlak, Anna; Forma, Ewa; Morawiec-Sztandera, Alina; Aleksandrowicz, Paweł; Lewy-Trenda, Iwona; and others

    2014-10-15

    Metallothioneins (MTs) are low molecular weight, cysteine-rich heavy metal-binding proteins which participate in the mechanisms of Zn homeostasis, and protect against toxic metals. MTs contain metal-thiolate cluster groups and suppress metal toxicity by binding to them. The aim of this study was to determine the − 5 A/G (rs28366003) single-nucleotide polymorphism (SNP) in the core promoter region of the MT2A gene and to investigate its effect on allele-specific gene expression and Cd, Zn and Cu content in squamous cell laryngeal cancer (SCC) and non-cancerous laryngeal mucosa (NCM) as a control. The MT2A promoter region − 5 A/G SNP was determined by restriction fragment length polymorphism using 323 SCC and 116 NCM. MT2A gene analysis was performed by quantitative real-time PCR. The frequency of A allele carriage was 94.2% and 91.8% in SCC and NCM, respectively, while G allele carriage was detected in 5.8% and 8.2% of SCC and NCM samples, respectively. As a result, a significant association was identified between the − 5 A/G SNP in the MT2A gene with mRNA expression in both groups. Metal levels were analyzed by flame atomic absorption spectrometry. The significant differences were identified between A/A and both the A/G and G/G genotypes, with regard to the concentration of the contaminating metal. The Spearman rank correlation results showed that the MT2A expression and Cd, Zn, Cu levels were negatively correlated. Results obtained in this study suggest that − 5 A/G SNP in MT2A gene may have an effect on allele-specific gene expression and accumulation of metal levels in laryngeal cancer. - Highlights: • MT2A gene expression and metal content in laryngeal cancer tissues • Association between SNP (rs28366003) and expression of MT2A • Significant associations between the SNP and Cd, Zn and Cu levels • Negative correlation between MT2A gene expression and Cd, Zn and Cu levels.

  10. Syntheses, crystal structures and fluorescent properties of Cd(II), Hg(II) and Ag(I) coordination polymers constructed from 1H-1,2,4-triazole-1-acetic acid

    SciTech Connect

    Ding Degang; Xie Lixia; Fan Yaoting; Hou Hongwei; Xu Yan

    2009-06-15

    Three new d{sup 10} coordination polymers, namely [Cd(taa)Cl]{sub n}1, [Hg(taa)Cl]{sub n}2, and [Ag{sub 1.5}(taa)(NO{sub 3}){sub 0.5}]{sub n}3 (taa=1H-1,2,4-triazole-1-acatate anion) have been prepared and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Compound 1 consists of two-dimensional layers constructed by carboxyl-linked helical chains, which are further linked through carboxyl group to generate a unique 3D open framework. Topological analysis reveals that the structure of 1 can be classified as an unprecedented (3,8)-connected network with the Schlaefli symbol (4.5{sup 2}){sub 2}(4{sup 2}.5{sup 8}.6{sup 14}.7{sup 3}.8). Compound 2 manifests a doubly interpenetrated decorated alpha-polonium cubic network with the Schlaefli symbol of (4{sup 10}.6{sup 2}.8{sup 3}). Compound 3 consists of 2D puckered layers made up of Ag centers and taa{sup -} bridges. In addition, all of these compounds are photoluminescent in the solid state with spectra that closely resemble those of the ligand precursor. - Graphical abstract: Three new compounds based on 1H-1,2,4-triazole-1-acetic acid and Cd(II), Hg(II) and Ag(I) salts display luminescent properties and may be potential candidates for luminescent materials.

  11. A first-principles study on the negative thermal expansion material: Mn3(A0.5B0.5)N (A=Cu, Zn, Ag, or Cd; B=Si, Ge, or Sn)

    NASA Astrophysics Data System (ADS)

    Qu, Bingyan; He, Haiyan; Pan, Bicai

    2016-07-01

    In this paper, using the first-principles calculations, we systemically study the magnetic and the negative thermal expansion (NTE) properties of Mn3(A0.5B0.5)N (A = Cu, Zn, Ag, or Cd; B = Si, Ge, or Sn). From the calculated results, except Mn3(Cu0.5Si0.5)N, all the doped compounds considered would exhibit the NTE. For the dopants at B sites, the working temperature of the NTE shifts to higher temperature range from Si to Sn, and among the compounds with these dopants, Mn3(A0.5Ge0.5)N has the largest amplitude of the NTE coefficient. As to the dopants at A sites, compared to Mn3(Cu0.5B0.5)N, Mn3(A0.5B0.5)N (A = Ag or Cd) exhibit the NTE with higher temperature ranges and lower coefficient of the thermal expansion. In a word, these compounds would have different working temperatures and coefficients of the NTE, which is important for the applications in different conditions.

  12. Complexation of Cd2+, Ni2+, and Ag+ metal ions with 4,13-didecyl-l,7,10,16-tetraoxa-4,13-diazacyclooctadecane in acetonitrile-ethylacetate binary mixtures

    NASA Astrophysics Data System (ADS)

    Izadyar, M.; Rounaghi, G. H.; Tarahomi, S.; Mohajeri, M.

    2013-12-01

    Conductometric titrations have been performed in acetonitrile-ethylacetate (AN-EtOAc) binary solutions at 288, 298, 308, and 318 K to obtain the stoichiometry, the complex stability constants and the standard thermodynamic parameters for the complexation of Cd2+, Ni2+, and Ag+ cations with 4,13-didecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane (cryptand 22DD). The stability constants of the resulting 1: 1 complexes formed between the metal cations and the ligand were determined by computer fitting of the conductance-mole ratio data. There is a non-linear relationship between the log K f values of complexes and the mole fraction of ethylacetate in the mixed solvent system. In addition, the conductometric data show that the stoichiometry of the complexes formed between the Cd2+, Ni2+, and Ag+ cations with the ligand changes with the nature of the solvent. The standard enthalpy and entropy values for the 1: 1 [ML] complexation reactions were evaluated from the temperature dependence of the formation constants. Thermodynamically, the complexation processes of the metal cations with the C22DD, is mainly entropy governed and the values of thermodynamic parameters are influenced by the nature and composition of the binary mixed solvent solutions.

  13. Spin relaxation characteristics in Ag nanowire covered with various oxides

    NASA Astrophysics Data System (ADS)

    Karube, S.; Idzuchi, H.; Kondou, K.; Fukuma, Y.; Otani, Y.

    2015-09-01

    We have studied spin relaxation characteristics in a Ag nanowire covered with various oxide layers of Bi2O3, Al2O3, HfO2, MgO, or AgOx by using non-local spin valve structures. The spin-flip probability, a ratio of momentum relaxation time to spin relaxation time at 10 K, exhibits a gradual increase with an atomic number of the oxide constituent elements, Mg, Al, Ag, and Hf. Surprisingly, the Bi2O3 capping was found to increase the probability by an order of magnitude compared with other oxide layers. This finding suggests the presence of an additional spin relaxation mechanism such as Rashba effect at the Ag/Bi2O3 interface, which cannot be explained by the simple Elliott-Yafet mechanism via phonon, impurity, and surface scatterings. The Ag/Bi2O3 interface may provide functionality as a spin to charge interconversion layer.

  14. Impacts of anthropogenic pressures on the water quality of the Gironde Estuary (SW France) from the Urban Agglomeration of Bordeaux: spatial characterization and inputs of trace metal elements (Ag, As, Cd, Cu, Pb and Zn)

    NASA Astrophysics Data System (ADS)

    Kessaci, Kahina; Coynel, Alexandra; Blanc, Gérard; Deycard, Victoria N.; Derriennic, Hervé; Schäfer, Jörg

    2014-05-01

    Recent European legislation (2000/60/CE) has listed eight trace metal elements as priority toxic substances for water quality. Urban metal inputs into hydrosystems are of increasing interest to both scientists and managers facing restrictive environmental protection policies, population increase and changing metal applications. The Gironde Estuary (SW France; 625 km2) is known for its metal/metalloid pollution originating from industrial (e.g. Cd, Zn, Cu, As, Ag, Hg) or agricultural sources (e.g. Cu) in the main fluvial tributaries (Garonne and Dordogne Rivers). However, little peer-reviewed scientific work has addressed the impact of urban sources on the Gironde Estuary, especially the Urban Agglomeration of Bordeaux (~1 million inhabitants) located on the downstream branch of the Garonne River. In this study, a snapshot sampling campaign was performed in 2011 for characterizing the spatial distribution of dissolved and particulate metal/metalloid (As, Ag, Cd, Pb, Zn, Cu) concentrations in three suburban watersheds: the Jalle of Blanquefort (330 km2), Eau Bourde (140 km2), and Peugue (112 km2). Furthermore, particulate metal Enrichment Factors (EF) were calculated using local geochemical background measured at the bottom of a sediment core (492 cm). Results indicated that metal concentrations displayed a high spatial variability depending on the suburban watershed and the studied element. Local concentrations anomalies were observed for: (i) As in the Eau Bourde River in dissolved (4.2 μg/l) and particulate phases (246 mg/kg; EF= 20) and attributed to a nearby industrial incinerator; (ii) Zn in the Peugue River with maximum dissolved and particulate concentrations of 87 μg/l and 1580 mg/kg (EF=17), respectively, probably due to urban habitation runoff; (iii) Ag in the Jalle of Blanquefort River with high dissolved (74 ng/l) and particulate concentrations (33.7 mg/kg; EF=117) due to industrial activities in the downstream part. Based on hydro

  15. Analytical performance of a lab-made concomitant metal analyzer to generate volatile species of Ag, Au, Cd, Cu, Ni, Sn and Zn using 8-hydroxyquinoline as a reaction media.

    PubMed

    Villanueva-Alonso, Julia; Peña-Vázquez, Elena; Bermejo-Barrera, Pilar

    2012-10-15

    This study evaluated the main parameters affecting Ag, Au, Cd, Cu, Ni, Sn and Zn vapor generation using a lab-made concomitant metal analyzer (CMA) as a reaction chamber and gas-liquid separator. The modifier used in the reaction media was 8-hydroxyquinoline, and Inductively-Coupled Plasma Optical Emission Spectrometry was used as detection technique. The performance of the lab-made concomitant analyzer was compared with the performance of a continuous flow gas-liquid separator and of a cyclonic spray chamber. Standards were prepared in acid media and included 1 mg L(-1) of Co as a catalyzer. The optimum concentrations of the reagents in the standards were: 450 mg L(-1) of 8-hydroxyquinoline and 0.4 M nitric acid. The optimum concentration of sodium borohydride to generate the vapors was 2.25% (w/v) (prepared in 0.4% (w/v) NaOH). The volatile species were swept from the CMA to the torch by an argon flow of 0.6 mL min(-1). The use of the CMA led to an improvement of the detection limits for some elements compared to conventional nebulization: 1.1 μg L(-1) for Ag, 7.0 μg L(-1) for Au and 4.3 μg L(-1) for Sn. The limit of detection for Cu was 1.4 μg L(-1) and for Ni 22.5 μg L(-1). The direct mixing of the reagents on the spray chamber was not effective for Cd and Zn; a deviation of the linearity was observed for these elements. PMID:23141310

  16. Syntheses, crystal structures and fluorescent properties of Cd(II), Hg(II) and Ag(I) coordination polymers constructed from 1H-1,2,4-triazole-1-acetic acid

    NASA Astrophysics Data System (ADS)

    Ding, De-Gang; Xie, Li-Xia; Fan, Yao-Ting; Hou, Hong-Wei; Xu, Yan

    2009-06-01

    Three new d10 coordination polymers, namely [Cd(taa)Cl] n1, [Hg(taa)Cl] n2, and [Ag 1.5(taa)(NO 3) 0.5] n3 (taa=1H-1,2,4-triazole-1-acatate anion) have been prepared and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Compound 1 consists of two-dimensional layers constructed by carboxyl-linked helical chains, which are further linked through carboxyl group to generate a unique 3D open framework. Topological analysis reveals that the structure of 1 can be classified as an unprecedented (3,8)-connected network with the Schläfli symbol (4.5 2) 2(4 2.5 8.6 14.7 3.8). Compound 2 manifests a doubly interpenetrated decorated α-polonium cubic network with the Schläfli symbol of (4 10.6 2.8 3). Compound 3 consists of 2D puckered layers made up of Ag centers and taa - bridges. In addition, all of these compounds are photoluminescent in the solid state with spectra that closely resemble those of the ligand precursor.

  17. Two kilometer long Bi-2212 ROSATwires

    NASA Astrophysics Data System (ADS)

    Sato, J.; Ohata, K.; Okada, M.; Tanaka, K.; Kitaguchi, H.; Kumakura, H.; Kiyoshi, T.; Wada, H.; Togano, K.

    2001-08-01

    We have developed a new type of Bi-2212/Ag round wire named rotation symmetric arranged tape-in-tube wire (ROSATwire). It displays excellent superconducting properties at low temperature. Our next step is to realize longer length ROSATwires for practical use. By combining the fabrication process of base structure ROSATwires with standard multi-filament wires, we have established a process for the fabrication of several-hundred meter class wires on a laboratory scale. 254 and 379 m long wires with Ag or Ag-Mg-Ni sheathing 1320 filaments showed an Ic of over 400 A, an overall Jc ( Je) of 160 A/mm 2, and a Jc of 700 A/mm 2. 2 km long Bi-2212/Ag round ROSATwires were also successfully fabricated due to a redesign of the wire structure.

  18. Synthesis and structural characterization of dinuclear Cd2+, Hg2+ and Fe2+ complexes with neutral bi and tetradentate flexible pyrazole-based ligands

    NASA Astrophysics Data System (ADS)

    Beheshti, Azizolla; Lalegani, Arash; Behvandi, Fatemeh; Safaeiyan, Forough; Sarkarzadeh, Afsoon; Bruno, Giuseppe; Amiri Rudbari, Hadi

    2015-02-01

    Four new complexes of [Hg2Cl4(bpp)]n (1), [Hg2Cl4(tdmpp)] (2), [Cd2I4(tdmpp)] (3) and [Fe2Cl4(tdmpp)] (4) were prepared by using the neutral N-donor ligands 1,3-bis(3,5-dimethyl-1-pyrazolyl)propane (bpp) and 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)propane (tdmpp) with different flexibility and appropriate metal salts of Cd(II), Hg(II) and Fe(II) ions. These compounds were characterized by the infrared spectroscopy, elemental analysis and X-ray crystallography. Flexible ligands and non-covalent Csbnd H⋯Cl hydrogen bonds play a major role in the crystal packing of compounds 1, 2 and 4. In the two-dimensional non-covalent structure of 1, there are two distinctly different coordination modes for the mercury atoms. One mercury atom has pseudo-trigonal bipyramidal geometry and the other adopts a distorted tetrahedral environment. In the dinuclear structures of 2 and 4 the neutral molecules are linked together by the Csbnd H⋯Cl hydrogen bonds, forming an infinite one-dimensional zigzag chain structure. Compounds 2-4 are isostructural with each other.

  19. Ferroelectric, piezoelectric, and dielectric properties of BiScO3-PbTiO3-Pb(Cd1/3Nb2/3)O3 ternary high temperature piezoelectric ceramics

    NASA Astrophysics Data System (ADS)

    Zhao, Tian-Long; Chen, Jianguo; Wang, Chun-Ming; Yu, Yang; Dong, Shuxiang

    2013-07-01

    (0.95-x)BiScO3-xPbTiO3-0.05Pb(Cd1/3Nb2/3)O3 (BS-xPT-PCN) high temperature piezoelectric ceramics near the morphotropic phase boundary (MPB) have been synthesized by traditional solid-state reaction methods. The microstructural morphology, phase structure, and electrical properties of BS-xPT-PCN ceramics were investigated in detail. X-ray diffraction analysis indicated BS-xPT-PCN ceramics have a pure perovskite structure. The coexistence of rhombohedral and tetragonal phases at MPB composition enhanced the polarizability by the coupling between two dynamically equivalent energy states, resulting in the improved piezoelectric and ferroelectric properties at MPB vicinity. The BS-xPT-PCN (x = 0.60) ceramics possess the optimal piezoelectric and ferroelectric properties with d33 = 505pC/N, kp = 55.9%, kt = 36.5%, strain = 0.23% (under the electric field 37.5 kV/cm), and Pr = 39.7 μC/cm2. High temperature dielectric behaviors showed diffuse phase transition in BS-xPT-PCN ceramics. The Curie temperature Tc was found to increase from 371 °C to 414 °C with x increasing from 0.58 to 0.62. All these results together with the good thermal stabilities make the BS-xPT-PCN ceramics promising candidates for high temperature piezoelectric applications.

  20. Bi- to tetravalent glycoclusters presenting GlcNAc/GalNAc as inhibitors: from plant agglutinins to human macrophage galactose-type lectin (CD301) and galectins.

    PubMed

    André, Sabine; O'Sullivan, Shane; Koller, Christiane; Murphy, Paul V; Gabius, Hans-Joachim

    2015-04-14

    Emerging insights into the functional spectrum of tissue lectins leads to identification of new targets for the custom-made design of potent inhibitors, providing a challenge for synthetic chemistry. The affinity and selectivity of a carbohydrate ligand for a lectin may immensely be increased by a number of approaches, which includes varying geometrical or topological features. This perspective leads to the design and synthesis of glycoclusters and their testing using assays of physiological relevance. Herein, hydroquinone, resorcinol, benzene-1,3,5-triol and tetra(4-hydroxyphenyl)ethene have been employed as scaffolds and propargyl derivatives obtained. The triazole-containing linker to the α/β-O/S-glycosides of GlcNAc/GalNAc presented on these scaffolds was generated by copper-catalysed azide-alkyne cycloaddition. This strategy was used to give a panel of nine glycoclusters with bi-, tri- and tetravalency. Maintained activity for lectin binding after conjugation was ascertained for both sugars in solid-phase assays with the plant agglutinins WGA (GlcNAc) and DBA (GalNAc). Absence of cross-reactivity excluded any carbohydrate-independent reactivity of the bivalent compounds, allowing us to proceed to further testing with a biomedically relevant lectin specific for GalNAc. Macrophage galactose(-binding C)-type lectin, involved in immune defence by dendritic cells and in virus uptake, was produced as a soluble protein without/with its α-helical coiled-coil stalk region. Binding to ligands presented on a matrix and on cell surfaces was highly susceptible to the presence of the tetravalent inhibitor derived from the tetraphenylethene-containing scaffold, and presentation of GalNAc with an α-thioglycosidic linkage proved favorable. Cross-reactivity of this glycocluster to human galectins-3 and -4, which interact with Tn-antigen-presenting mucins, was rather small. Evidently, the valency and spatial display of α-GalNAc residues is a key factor to design potent and

  1. 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.

  2. {bold {ital In situ}} measurements of texture and phase development in (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}{endash}Ag tapes

    SciTech Connect

    Thurston, T.R.; Haldar, P.; Wang, Y.L.; Suenaga, M.; Jisrawi, N.M. |; Wildgruber, U.

    1997-04-01

    Hard x-rays from a synchrotron source were utilized in diffraction experiments performed at elevated temperatures (up to {approximately}870{degree}C) on (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} (Bi-2223) tapes {ital completely} encased in silver. The general behavior of the phase and texture development under typical processing conditions was determined, and the effects that several variations in processing conditions had on the phase and texture development were examined. These results and their implications for improving processing conditions are discussed. {copyright} {ital 1997 Materials Research Society.}

  3. Valence Fluctuations Revealed by Magnetic Field and Pressure Scans: Comparison with Experiments in YbXCu4 (X=In, Ag, Cd) and CeYIn5 (Y=Ir, Rh)

    NASA Astrophysics Data System (ADS)

    Watanabe, Shinji; Tsuruta, Atsushi; Miyake, Kazumasa; Flouquet, Jacques

    2009-10-01

    The mechanism of how critical end points of the first-order valence transition (FOVT) are controlled by a magnetic field is discussed. We demonstrate that critical temperature is suppressed to be a quantum critical point (QCP) by a magnetic field. This results explain the field dependence of the isostructural FOVT observed in Ce metal and YbInCu4. Magnetic field scan can make the system reenter in a critical valence fluctuation region. Even in intermediate-valence materials, the QCP is induced by applying a magnetic field, at which magnetic susceptibility also diverges. The driving force of the field-induced QCP is shown to be a cooperative phenomenon of the Zeeman effect and the Kondo effect, which creates a distinct energy scale from the Kondo temperature. The key concept is that the closeness to the QCP of the FOVT is vital in understanding Ce- and Yb-based heavy-fermions. This explains the peculiar magnetic and transport responses in CeYIn5 (Y=Ir, Rh) and metamagnetic transition in YbXCu4 for X=In as well as the sharp contrast between X=Ag and Cd.

  4. High energy proton irradiation induced pinning centers in Bi-2212 and Bi-2223 superconductors

    SciTech Connect

    Willis, J.O.; Safar, H.; Cho, J.H.

    1995-12-01

    Bi-2212 single crystals and Bi-2223/Ag-sheathed tapes were irradiated with high energy protons. TEM images reveal the production of randomly oriented (splayed) columnar defects with an amorphous core of {approximately}10 nm diameter caused by the fissioning of Bi nuclei. The critical current density J{sub c} and irreversibility line both substantially increased with the proton dose for both crystals and tapes, especially for the magnetic field parallel to the c axis. An irradiated tape had a J{sub c} value {approximately}100 times greater than that of an unirradiated one at 1 T and 75 K.

  5. Ferroelectric, piezoelectric, and dielectric properties of BiScO{sub 3}-PbTiO{sub 3}-Pb(Cd{sub 1/3}Nb{sub 2/3})O{sub 3} ternary high temperature piezoelectric ceramics

    SciTech Connect

    Zhao Tianlong; Chen Jianguo; Dong Shuxiang; Wang Chunming; Yu Yang

    2013-07-14

    (0.95-x)BiScO{sub 3}-xPbTiO{sub 3}-0.05Pb(Cd{sub 1/3}Nb{sub 2/3})O{sub 3} (BS-xPT-PCN) high temperature piezoelectric ceramics near the morphotropic phase boundary (MPB) have been synthesized by traditional solid-state reaction methods. The microstructural morphology, phase structure, and electrical properties of BS-xPT-PCN ceramics were investigated in detail. X-ray diffraction analysis indicated BS-xPT-PCN ceramics have a pure perovskite structure. The coexistence of rhombohedral and tetragonal phases at MPB composition enhanced the polarizability by the coupling between two dynamically equivalent energy states, resulting in the improved piezoelectric and ferroelectric properties at MPB vicinity. The BS-xPT-PCN (x = 0.60) ceramics possess the optimal piezoelectric and ferroelectric properties with d{sub 33} = 505pC/N, k{sub p} = 55.9%, k{sub t} = 36.5%, strain = 0.23% (under the electric field 37.5 kV/cm), and P{sub r} = 39.7 {mu}C/cm{sup 2}. High temperature dielectric behaviors showed diffuse phase transition in BS-xPT-PCN ceramics. The Curie temperature T{sub c} was found to increase from 371 Degree-Sign C to 414 Degree-Sign C with x increasing from 0.58 to 0.62. All these results together with the good thermal stabilities make the BS-xPT-PCN ceramics promising candidates for high temperature piezoelectric applications.

  6. Synthesis of homo and hetero metal-phosphonate frameworks from bi-functional aminomethylphosphonic acid

    SciTech Connect

    Samanamu, Christian R.; Zamora, Elena Nicole; Montchamp, Jean-Luc; Richards, Anne F.

    2008-06-15

    The reaction between aminomethylphosphonic acid (ampa) and the metal salts of Zn, Cd, Hg, Pb, Ag, and Cu afforded seven metal-phosphonate polymers with unique structural features and includes the synthesis of a bimetallic metal-organic framework (Cu/Ag). The characterization of these metal phosphonates is reported by means of infrared spectroscopy, {sup 1}H-NMR, {sup 31}P-NMR, X-ray crystallography, energy dispersive X-ray (EDX), and thermogravimetric analysis (TGA). Individual structural features are compared based on the preferred coordination mode of ampa and the geometrical requirements for each metallic center that manipulates the structural motif. - Graphical abstract: The synthesis and characterization of polymeric metal phosphonates featuring zinc, cadmium, mercury, lead, and silver phosphonate are described from the reactions of the bi-funtional aminomethylphosphonic acid with the metal precursor in aqueous conditions. These previously undescribed polymers display unusual structural features and include the synthesis of a bimetallic metal-organic framework (Cu/Ag)

  7. The electrical and magnetic properties of the (Bi{sub 1{minus}y}Cd{sub y})Sr{sub 2}(Y{sub 1{minus}x}Ca{sub x})Cu{sub 2}O{sub 7{minus}{delta}} series

    SciTech Connect

    Beales, T.P.; Parberry, J.M.

    1997-09-01

    (Bi{sub 0.33}Cd{sub 0.67})Sr{sub 2}YCu{sub 2}O{sub 7{minus}{delta}} can be synthesized single phase by XRD, between 800 and 950 C. It has a tetragonal structure, space group P4/mmm, and lattice parameters a = 3.802 {angstrom} and c = 11.96 {angstrom}. The Cd site can be fully replaced with an appropriate M{sup 11} ion and the Y site can be chemically substituted up to 100% by lanthanide ions with ionic radii falling between those of Nd and Gd, with a measurable shift in a and c axis lattice parameters. As synthesized, (Bi{sub 0.33}Cd{sub 0.67})Sr{sub 2}YCu{sub 2}O{sub 7{minus}{delta}} is semiconducting and paramagnetic down to 4 K. Superconductivity can be induced by a post-synthesis annealing in high pressure oxygen to give {Tc} = 40 K. Thermopower measurements show that the material is underdoped with S{sub 290K} = 50 {mu}VK{sup {minus}1}. Introduction of extra charge carriers to raise {Tc} by doping Ca on the Y site is not chemically possible with the synthesis techniques used.

  8. Bismuth-induced deep levels and carrier compensation in CdTe

    SciTech Connect

    Du, Mao-Hua

    2008-01-01

    First-principles calculations show that Bi on Cd site in CdTe can be either a donor, Bi_Cd+, or an acceptor, Bi_Cd- , depending on the Fermi level. The can bind a substitutional O (O_Te) with large binding energy of 1.40 eV. The calculated (0/-) transition level for B_Cd- - O_Te complex is in good agreement with the observed deep hole trapping level. Bi can also substitute Te to form an acceptor. The amphoteric nature of Bi in CdTe results in the pinning of the Fermi level and the high resistivity. We also discuss the origin of p-type CdTe at high Bi doping level.

  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. Luminescence efficiency growth in wide band gap semiconducting Bi2O3 doped Cd0.4Pb0.1B0.5 glasses and effect of γ-irradiation

    NASA Astrophysics Data System (ADS)

    Marzouk, M. A.; Ibrahim, S.; Hamdy, Y. M.

    2014-11-01

    Cadmium lead borate glasses together with other glasses containing different Bi2O3-doping concentrations (2.5, 5, 7.5, 10 mol%) were prepared by conventional melt annealing method. The density and molar volume values were calculated to obtain some insight on the packing density and arrangement in the network. Also their optical and structural properties have been characterized by means of X-ray diffraction, UV-visible spectroscopy, luminescence spectroscopy and FTIR spectroscopy. Optical measurements have been used to determine the optical band gap (Eg), Urbach energy (ΔE) and the refractive index (n). The results demonstrate the effective rule of Bi2O3 on the studied glasses. The undoped and Bi2O3 doped - glass show strong extended UV-near visible absorption bands which are attributed to the collective presence of both trace iron impurities from raw materials and also the sharing of bismuth Bi+3 ions. Furthermore, the luminescence intensity strongly increases with increasing Bi2O3 content which may be attributed to transfer of energy from transitions in its energy levels. It has been revealed that the decreasing values of optical band gap and band tail can be understood and related in terms of the structural changes that are taking place in the glass samples. The infrared absorption spectra of the prepared glasses show characteristic absorption bands related to the borate network (BO3, BO4 groups) together with vibrational modes due to Bi-O groups upon the introduction of Bi2O3. The prepared samples reveal a very limited response towards of gamma irradiation which reflects its shielding behavior towards the effect of such type of irradiation.

  11. Spin relaxation characteristics in Ag nanowire covered with various oxides

    SciTech Connect

    Karube, S.; Idzuchi, H.; Otani, Y.; Kondou, K.; Fukuma, Y.

    2015-09-21

    We have studied spin relaxation characteristics in a Ag nanowire covered with various oxide layers of Bi{sub 2}O{sub 3}, Al{sub 2}O{sub 3}, HfO{sub 2}, MgO, or AgO{sub x} by using non-local spin valve structures. The spin-flip probability, a ratio of momentum relaxation time to spin relaxation time at 10 K, exhibits a gradual increase with an atomic number of the oxide constituent elements, Mg, Al, Ag, and Hf. Surprisingly, the Bi{sub 2}O{sub 3} capping was found to increase the probability by an order of magnitude compared with other oxide layers. This finding suggests the presence of an additional spin relaxation mechanism such as Rashba effect at the Ag/Bi{sub 2}O{sub 3} interface, which cannot be explained by the simple Elliott-Yafet mechanism via phonon, impurity, and surface scatterings. The Ag/Bi{sub 2}O{sub 3} interface may provide functionality as a spin to charge interconversion layer.

  12. Visible-light driven degradation of ibuprofen using abundant metal-loaded BiVO₄ photocatalysts.

    PubMed

    Bian, Zhao-Yong; Zhu, Ya-Qi; Zhang, Jun-Xiao; Ding, Ai-Zhong; Wang, Hui

    2014-12-01

    An efficient method for the degradation of ibuprofen as an aqueous contaminant was developed under visible-light irradiation with as-prepared bismuth vanadate (BiVO4) catalysts. The metal-loaded catalysts Cu-BiVO4 and Ag-BiVO4 were synthesized using a hydrothermal process and then a wet-impregnation method. All of the materials were fully characterized by X-ray diffraction, scanning electron microscopy, UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and BET surface area. The results indicated that all of the prepared samples had monoclinic scheelite structures. In the metal-loaded catalysts, silver existed as a mixture of Ag and Ag2O on the surface of the catalysts. However, copper existed as Cu2O and CuO. Additionally, the band gap values of BiVO4, Ag-BiVO4, and Cu-BiVO4 were 2.38, 2.31, and 2.30eV, respectively. Compared to the BiVO4 catalyst, the metal-loaded BiVO4 catalysts showed superior photocatalytic properties for the degradation of ibuprofen. PMID:25268078

  13. Ag(I)-binding to phytochelatins.

    PubMed

    Mehra, R K; Tran, K; Scott, G W; Mulchandani, P; Saini, S S

    1996-02-01

    Phytochelatins (PCs) are glutathione-derived peptides with the general structure (gamma-Glu-Cys)nGly, where n varies from 2 to 11. A variety of metal ions such as Cu(II), Cd(II), Pb(II), Zn(II), and Ag(I) induce PC synthesis in plants and some yeasts. It has generally been assumed that the inducer metals also bind PCs. However, very little information is available on the binding of metals other than Cu(I) and Cd(II) to PCs. In this paper, we describe the Ag(I)-binding characteristics of PCs with the structure (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly, and (gamma-Glu-Cys)4Gly. The Ag(I)-binding stoichiometries of these three peptides were determined by (i) UV/VIS spectrophotometry, (ii) luminescence spectroscopy at 77 K, and (iii) reverse-phase HPLC. The three techniques yielded similar results. ApoPCs exhibit featureless absorption in the 220-340 nm range. The binding of Ag(I) to PCs induced the appearance of specific absorption shoulders. The titration end point was indicated by the flattening of the characteristic absorption shoulders. Similarly, luminescence at 77 K due to Ag(I)-thiolate clusters increased with the addition of graded Ag(I) equivalents. The luminescence declined when Ag(I) equivalents in excess of the saturating amounts were added to the peptides. At neutral pH, (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly, and (gamma-Glu-Cys)4Gly bind 1.0, 1.5, and 4.0 equivalents of Ag(I), respectively. The Ag(I)-binding capacity of (gamma-Glu-Cys)2Gly and (gamma-Glu-Cys)3Gly was increased at pH 5.0 and below so that Ag(I)/-SH ratio approached 1.0. A similar pH-dependent binding of Ag(I) to glutathione was also observed. The increased Ag(I)-binding to PCs at lower pH is of physiological significance as these peptides accumulate in acidic vacuoles. We also report lifetime data on Ag(I)-PCs. The relatively long decay-times (approximately 0.1-0.3 msec) accompanied with a large Stokes shift in the emission band are indicative of spin-forbidden phosphorescence. PMID

  14. Better CD4+ T cell recovery in Brazilian HIV-infected individuals under HAART due to cumulative carriage of SDF-1-3'A, CCR2-V64I, CCR5-D32 and CCR5-promoter 59029A/G polymorphisms.

    PubMed

    Rigato, Paula O; Hong, Marisa A; Casseb, Jorge; Ueda, Mirthes; de Castro, Isac; Benard, Gil; Duarte, Alberto J S

    2008-09-01

    Polymorphisms of chemokines and chemokine-receptors genes have been shown to influence the rate of progression to AIDS; however, their influence on response to HAART remains unclear. We investigated the frequency of the SDF-1-3'A, CCR2-64I, CCR5-D32 and CCR5-Promoter-59029-A/G polymorphisms in Brazilian HIV-1-infected and uninfected individuals and their influence on CD4+ T-cell evolution HIV-1 infected individuals before and during HAART. Polymorphism detection was done in a transversal study of 200 HIV-1-infected and 82 uninfected individuals. The rate of CD4+ T cell increase or decrease was studied in a cohort of 155 HIV-1 infected individuals on pre and post-HAART. Polymorphisms were determined by PCR associated with RFLP. The rate of CD4+ T-cell decline or increase was also determined. HIV-1 infected and uninfected subjects showed, respectively, frequencies of 0.193 and 0.220 for SDF-1-3'A, of 0.140 and 0.110 for CCR2-V64I, of 0.038 and 0.055 for CCR5-D32, and of 0.442 and 0.390 for CCR5-P-59029-A/G. HIV-1-infected subjects carrying one, two or three of these four polymorphisms showed better CD4+ T-cell recovery than HIV-1-infected subjects carrying the four wild-type alleles (+2.7, +1.6, +3.5, and -0.9 lymphocytes/microl/month, respectively). Regression logistic analysis showed that the CCR5-D32/CCR2-V64I association was predictor of positive CD4+ T cell slope after HAART. The distribution of polymorphisms did not differ between HIV-1-infected and uninfected individuals, but differed from more homogenous ethnic groups probably reflecting the miscegenation of the Brazilian population. We add further evidence of the role of these polymorphisms by showing that the CD4 gain was influenced by carriage of one or more of the polymorphisms studied here. These results highlight the possibility that these genetic traits can be useful to identify patients at risk for faster progression to AIDS or therapeutic failure. PMID:18855658

  15. Comparative analysis of crystal-field parameters for rare-earth ions at monoclinic sites in AB(WO4)2 crystals: II. Pr3+ and Nd3+ ions in KRE(WO4)2 (RE = Y or Gd), Pr3+ ions in M+ Bi(XO4)2 (M+ = Li or Na and X = W or Mo), and Nd3+ ions in NaBi(WO4)2 and AgNd(WO4)2.

    PubMed

    Rudowicz, Czesław; Karbowiak, Mirosław; Gnutek, Paweł; Lewandowska, Monika

    2014-02-12

    In part I, the crystal-field (CF) parameter (CFP) sets for important potential solid state laser systems Tm(3+), Ho(3+), and Er(3+) ions in KGd(WO4)2 and Tm(3+) ions in KLu(WO4)2 were thoroughly revisited using a general framework for the analysis of CF levels and CFP modeling. In this part the non-standard CFP sets for Pr(3+) and Nd(3+) ions in KR(WO4)2 (R = Y or Gd) and the standard CFP sets for Pr(3+) ions in M(+)Bi(XO4)2 (M(+) = Li or Na and X = W or Mo) and Nd(3+) ions in the related systems NaBi(WO4)2 and AgNd(WO4)2 are analyzed. Due to structural similarity of the hosts, the CFP values for a given trivalent rare-earth (RE(3+)) ion should be quite close in these systems. However, the fitted (and model) CFP sets appear disparate for the systems in question. The standardization criteria are utilized to ensure direct comparability of the apparently disparate CFP sets reported in the literature. The CFP sets standardized by us are compared with the originally standard CFP sets for Pr(3+) and Nd(3+) ions in related AB(XO4)2 systems. Following part I, we argue that meaningful analysis of the mixed CFP sets, i.e. standard and non-standard ones, must take into account the intrinsic features of CF Hamiltonians for orthorhombic and lower symmetry cases, which have not been fully recognized in the literature as yet. The model or fitted CFP sets that belong to disparate regions in the CFP space are intrinsically incompatible, i.e. such sets should not be directly compared. The correlated alternative CFP sets are calculated using monoclinic standardization transformations. The closeness of the standardized CFP sets is assessed in a quantitative way using the closeness factors and the norms ratios. Comparative analysis of the monoclinic CFP sets reported for the titled ion-host systems is carried out and several inconsistencies in the previous studies are clarified. The CFP sets determined by standardization are utilized as starting sets for applications of the multiple

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  17. Cellular and molecular requirements for the recall of IL-4-producing memory CD4(+)CD45RO(+)CD27(-) T cells during protection induced by attenuated Plasmodium falciparum sporozoites.

    PubMed

    Palmer, Dupeh R; Krzych, Urszula

    2002-03-01

    The requirements for maintenance of antigen (Ag)-specific memory T cells in protection to malaria is poorly understood. We have previously demonstrated a recall of IL-4-producing memory CD4(+)CD45RO(+) T cells with parasitized red blood cells (pRBC) in persons protected by radiation-attenuated Plasmodium falciparum sporozoites (gamma-spz). Using the CD27 marker, we have now identified two subsets of CD4(+)CD45RO(+) T cells: CD4(+)CD45RO(+)CD27(+) T cells representing an early memory and CD4(+)CD45RO(+)CD27() T cells representing a terminally differentiated memory cells. A small subset of CD4(+)CD45RO(+)CD27(-) T cells also expressed CD70, the CD27 ligand. The addition of anti-CD70 monoclonal antibody (mAb) to pRBC-stimulated cultures significantly inhibited the conversion of CD27(+) to CD27(-) subset without profoundly affecting IL-4 production. In contrast, the inclusion of anti-CD27 mAb in parallel cultures abrogated IL-4 production without interfering with conscription of T cells into the CD27(-) T cell set. We propose that the persistence of memory CD4(+) T cells depends on Ag-driven conscription of a mature memory phenotype through co-ligation of CD27 and CD70 expressed, respectively, on CD27(+) and CD27(-) T cells. Hence, protracted protection in malaria depends in part on memory CD4(+) T cells that require specific Ag presumably from the repositories of liver-and blood-stage antigens and the delivery of a second signal from the CD27:CD70 interaction. PMID:11857339

  18. Levels of human platelet-derived soluble CD40 ligand depend on haplotypes of CD40LG-CD40-ITGA2

    PubMed Central

    Aloui, Chaker; Prigent, Antoine; Tariket, Sofiane; Sut, Caroline; Fagan, Jocelyne; Cognasse, Fabrice; Chakroun, Tahar; Garraud, Olivier; Laradi, Sandrine

    2016-01-01

    Increased circulating soluble CD40 ligand (sCD40L) is commonly associated with inflammatory disorders. We aimed to investigate whether gene polymorphisms in CD40LG, CD40 and ITGA2 are associated with a propensity to secrete sCD40L; thus, we examined this issue at the level of human platelets, the principal source of sCD40L. We performed single polymorphism and haplotype analyses to test for the effect of twelve polymorphisms across the CD40LG, CD40 and ITGA2 genes in blood donors. ITGA2 presented a positive association with rs1126643, with a significant modification in sCD40L secretion (carriers of C allele, P = 0.02), unlike the investigated CD40LG and CD40 polymorphisms. One CD40LG haplotype (TGGC) showing rs975379 (C/T), rs3092952 (A/G), rs3092933 (A/G) and rs3092929 (A/C) was associated with increased sCD40L levels (1.906 μg/L (95% CI: 1.060 to 2.751); P = 0.000009). The sCD40L level was associated with the inter-chromosomal CD40LG/CD40/ITGA2 haplotype (ATC), displaying rs3092952 (A/G), rs1883832 (C/T) and rs1126643 (C/T), with increased sCD40L levels (P = 0.0135). Our results help to decipher the genetic role of CD40LG, CD40 and ITGA2 with regard to sCD40L levels found in platelet components. Given the crucial role of sCD40L, this haplotype study in a transfusion model may be helpful to further determine the role of haplotypes in inflammatory clinical settings. PMID:27094978

  19. LcBiP, a endoplasmic reticulum chaperone binding protein gene from Lycium chinense, confers cadmium tolerance in transgenic tobacco.

    PubMed

    Guan, Chunfeng; Jin, Chao; Ji, Jing; Wang, Gang; Li, Xiaozhou

    2015-01-01

    Cadmium (Cd) accumulation is very toxic to plants. The presence of Cd may lead to excessive production of reactive oxygen species (ROS), and then cause inhibition of plant growth. The endoplasmic reticulum chaperone binding protein (BiP) is an important functional protein, which has been shown to function as a sensor of alterations in the ER environment. BiP overexpression in plants was shown to increase drought tolerance through inhibition of ROS accumulation. Due to the above relationships, it is likely that there may be a link between Cd stress tolerance, ROS accumulation and the BiP transcript expression in plants. In this study, a BiP gene, LcBiP, from L. chinense was isolated and characterized. Overexpression of LcBiP in tobacco conferred Cd tolerance. Under Cd stress conditions, the transgenic tobacco lines exhibited better chlorophyll retention, less accumulation of ROS, longer root length, more glutathione (GSH) content, and less antioxidant enzyme activity than the wild type. These data demonstrated that LcBiP act as a positive regulator in Cd stress tolerance. It is hypothesized that the improved Cd tolerance of the transgenic tobacco plants may be due to the enhanced ROS scavenging capacity. The enhancement of GSH content might contribute to this ROS scavenging capacity in the transgenic plants. However, the underlying mechanism for BiP-mediated increase in Cd stress tolerance need to be further clarified. PMID:25589446

  20. Effects of Ce Addition on the Microstructure and Mechanical Properties of Sn-58Bi Solder Joints

    NASA Astrophysics Data System (ADS)

    Chuang, Tung-Han; Wu, Hsing-Fei

    2011-01-01

    The effects of a rare-earth element on the microstructure, mechanical properties, and whisker growth of Sn-58Bi alloys and solder joints in ball grid array (BGA) packages with Ag/Cu pads have been investigated. Mechanical testing indicated that the elongation of Sn-58Bi alloys doped with Ce increased significantly, and the tensile strength decreased slightly, in compar- ison with undoped Sn-58Bi. In addition, the growth of both fiber- and hillock-shaped tin whiskers on the surface of Sn-58Bi-0.5Ce was retarded in the case of Sn-3Ag-0.5Cu-0.5Ce alloys. The growth of interfacial intermetallic compounds (IMC) in Sn-58Bi-0.5Ce solder joints was slower than that in Sn-58Bi because the activity of Ce atoms at the interface of the Cu6Sn5 IMC/solder was reduced. The reflowed Sn-58Bi and Sn-58Bi-0.5Ce BGA packages with Ag/Cu pads had a ball shear strength of 7.91 N and 7.64 N, which decreased to about 7.13 N and 6.87 N after aging at 100°C for 1000 h, respectively. The reflowed and aged solder joints fractured across the solder balls with ductile characteristics after ball shear tests.

  1. Partical Melting of bulk Bi-2212

    NASA Technical Reports Server (NTRS)

    Heeb, B.; Gauckler, L. J.

    1995-01-01

    Dense and textured Bi-2212 bulk samples have been produced by the partial melting process. The appropriate amount of liquid phase necessary for complete densification has been adjusted by controlling the maximum processing temperature. The maximum temperature itself has to be adapted to several parameters as powder stoichiometry, silver addition and oxygen partial pressure. Prolonged annealing at 850 and 820 C and cooling in N2 atmosphere led to nearly single phase material with T(sub c) = 92 K. Critical current densities j(sub c) of 2'200 A/sq cm at 77 K/0 T have been achieved in samples of more than 1 mm thickness. Reducing the thickness below 0.4 mm enhances j(sub c) considerably to values is greater than 4'000 A/sq cm. The addition of 2 wt% Ag decreases the solidus temperature of the Bi-2212 powder by 21 C. Therefore, the maximum heat treatment temperature of Ag containing samples can be markedly lowered leading to a reduction of the amount of secondary phases. In addition, Ag enhances slightly the texture over the entire cross section and as a result j(sub c) at 77 K/0 T.

  2. The Role of Crop Cd Bioavailability in Potential for Transfer of Soil Cd Risk to Humans and Wildlife

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cd is a common contaminant in soils affected by mining and smelting of Zn, Pb, Cu and Ag ores and where biosolids, composts and manures are applied. Zn is usually present at 100-200 times higher concentrations than Cd. Because of this relationship of Cd and Zn in ores and contaminated soils, Zn is...

  3. Preparation, characterization, and anti-Helicobacter pylori activity of Bi3+-Hericium erinaceus polysaccharide complex.

    PubMed

    Zhu, Yang; Chen, Yao; Li, Qian; Zhao, Ting; Zhang, Ming; Feng, Weiwei; Takase, Mohammed; Wu, Xueshan; Zhou, Zhaoxiang; Yang, Liuqing; Wu, Xiangyang

    2014-09-22

    Two new Bi3+-Hericium erinaceus polysaccharide (BiHEP) complexes were prepared using Bi3+ and two purified polysaccharides from H. erinaceus (HEPs), respectively. The complexes were characterized by elemental analysis, FT-IR, CD, SEM, AFM, XRD, and TG. The anti-Helicobacter pylori (Hp) activities in vitro by agar dilution assay of the complexes were evaluated. The molecular weights of HEPs were 197 and 20 kDa, respectively. All the analyses confirmed the formation of new BiHEP complexes with lower content of Bi3+ compared with colloidal bismuth subcitrate (CBS), the most utilized bismuth preparation clinically. Furthermore, HEPs themselves have definite inhibition effects on Hp, and BiHEP complexes have lower content of Bi exhibited strong inhibition effects on Hp (MIC=20 μg/mL), similar to that of CBS with higher content of Bi. The study provides a basis for further development of multiple treatments of Hp infection or new medicines. PMID:24906751

  4. 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

  5. Limiting current mechanisms of Bi2223 wires in magnetic fields

    NASA Astrophysics Data System (ADS)

    Kobayashi, S.; Yamade, S.; Kikuchi, M.; Yamazaki, K.; Fujikami, J.; Ayai, N.; Hayashi, K.; Sato, K.; Hata, R.; Kitaguti, H.

    2008-05-01

    Controlled overpressure (CT-OP) processing eliminates pores and heals cracks, which densifies the Bi2223 filaments and increases the critical current of Ag-sheathed Bi2223 wire. High current capacity wires with critical current values around 210 A at 77 K and self-field have been achieved. The enhancement of the current capacity seems to be due to reducing the weak links between Bi2223 grains and improving the flux pinning. In order to understand the mechanisms for transport critical current in Bi2223 wires, the dependence of the critical current on magnetic field and temperature has been investigated. The critical current is measured as a function of the perpendicular and parallel magnetic fields, up to 12 T, at temperatures ranging from 4.2 to 90 K. These results indicate that higher critical current is associated with highly textured and well connected Bi2223 grains. To further improve a critical current of Bi2223 wires, it is necessary to decrease the misalignment angle and reduce the fraction of Bi2212 and secondary phases.

  6. Contrasting the Role of Mg and Ba Doping on the Microstructure and Thermoelectric Properties of p-Type AgSbSe2.

    PubMed

    Liu, Zihang; Shuai, Jing; Geng, Huiyuan; Mao, Jun; Feng, Yan; Zhao, Xu; Meng, Xianfu; He, Ran; Cai, Wei; Sui, Jiehe

    2015-10-21

    Microstructure has a critical influence on the mechanical and functional properties. For thermoelectric materials, deep understanding of the relationship of microstructure and thermoelectric properties will enable the rational optimization of the ZT value and efficiency. Herein, taking AgSbSe2 as an example, we first report a different role of alkaline-earth metal ions (Mg(2+) and Ba(2+)) doping in the microstructure and thermoelectric properties of p-type AgSbSe2. For Mg doping, it monotonously increases the carrier concentration and then reduces the electrical resistivity, leading to a substantially enhanced power factor in comparison to those of other dopant elements (Bi(3+), Pb(2+), Zn(2+), Na(+), and Cd(2+)) in the AgSbSe2 system. Meanwhile, the lattice thermal conductivity is gradually suppressed by point defects scattering. In contrast, the electrical resistivity first decreases and then slightly rises with the increased Ba-doping concentrations due to the presence of BaSe3 nanoprecipitates, exhibiting a different variation tendency compared with the corresponding Mg-doped samples. More significantly, the total thermal conductivity is obviously reduced with the increased Ba-doping concentrations partially because of the strong scattering of medium and long wavelength phonons via the nanoprecipitates, consistent with the theoretical calculation and analysis. Collectively, ZT value ∼1 at 673 K and calculated leg efficiency ∼8.5% with Tc = 300 K and Th = 673 K are obtained for both AgSb0.98Mg0.02Se2 and AgSb0.98Ba0.02Se2 samples. PMID:26434693

  7. One-pot solvothermal preparation and enhanced photocatalytic activity of metallic silver and graphene co-doped BiVO4 ternary systems

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Wei, Yongge; Guo, Wan; Guo, Yihang; Guo, Yingna

    2015-03-01

    A series of metallic silver and graphene (GR) co-doped monoclinic BiVO4 ternary systems (Ag/GR/BiVO4) are demonstrated by a single-step solvothermal method. The phase and chemical structure, morphology, textural and optical absorption properties of the Ag/GR/BiVO4 ternary systems are well characterized, and then their simulated sunlight and visible-light photocatalytic activity were evaluated by the degradation of a typical dye pollutant, rhodamine B (RhB). For comparison, binary systems of Ag/BiVO4 and GR/BiVO4 as well as solitary BiVO4 are also tested under the same conditions. Meanwhile, the separation and transportation of the photogenerated carriers in the simulated sunlight-irradiating Ag/GR/BiVO4 ternary systems are studied by photoelectrochemistry experiments, and the active species generated during the process of photodegradation are investigated by free radical and hole scavenging experiments. On the basis of the above results, mechanism of photocatalytic degradation of RhB over the Ag/GR/BiVO4 ternary system is revealed. Finally, the reusability of the catalyst was evaluated by five consecutive catalytic runs.

  8. 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.

  9. Strategic BI for All

    ERIC Educational Resources Information Center

    Raths, David

    2008-01-01

    Implementing a complex business intelligence (BI) system at a small school or one with limited resources can seem daunting. For small to midsize schools and community colleges, a strategic BI initiative may still be an elusive goal. This article discusses how schools with limited resources are making the dream a reality.

  10. 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.

  11. Refinement of the canine CD1 locus topology and investigation of antibody binding to recombinant canine CD1 isoforms.

    PubMed

    Schjaerff, Mette; Keller, Stefan M; Fass, Joseph; Froenicke, Lutz; Grahn, Robert A; Lyons, Leslie; Affolter, Verena K; Kristensen, Annemarie T; Moore, Peter F

    2016-03-01

    CD1 molecules are antigen-presenting glycoproteins primarily found on dendritic cells (DCs) responsible for lipid antigen presentation to CD1-restricted T cells. Despite their pivotal role in immunity, little is known about CD1 protein expression in dogs, notably due to lack of isoform-specific antibodies. The canine (Canis familiaris) CD1 locus was previously found to contain three functional CD1A genes: canCD1A2, canCD1A6, and canCD1A8, where two variants of canCD1A8, canCD1A8.1 and canCD1A8.2, were assumed to be allelic variants. However, we hypothesized that these rather represented two separate genes. Sequencing of three overlapping bacterial artificial chromosomes (BACs) spanning the entire canine CD1 locus revealed canCD1A8.2 and canCD1A8.1 to be located in tandem between canCD1A7 and canCD1C, and canCD1A8.1 was consequently renamed canCD1A9. Green fluorescent protein (GFP)-fused canine CD1 transcripts were recombinantly expressed in 293T cells. All proteins showed a highly positive GFP expression except for canine CD1d and a splice variant of canine CD1a8 lacking exon 3. Probing with a panel of anti-CD1 monoclonal antibodies (mAbs) showed that Ca13.9H11 and Ca9.AG5 only recognized canine CD1a8 and CD1a9 isoforms, and Fe1.5F4 mAb solely recognized canine CD1a6. Anti-CD1b mAbs recognized the canine CD1b protein, but also bound CD1a2, CD1a8, and CD1a9. Interestingly, Ca9.AG5 showed allele specificity based on a single nucleotide polymorphism (SNP) located at position 321. Our findings have refined the structure of the canine CD1 locus and available antibody specificity against canine CD1 proteins. These are important fundamentals for future investigation of the role of canine CD1 in lipid immunity. PMID:26687789

  12. Sintering of bulk high- Tc superconductors: Bi-Sr-Ca-Cu-O

    SciTech Connect

    Goretta, K.C.; Lanagan, M.T.; Kaufman, D.Y.; Biondo, A.C.; Wu, C.T.; Loomans, M.E.; Cheesman, M.R.; Poeppel, R.B. ); Nash, A.S. )

    1992-05-01

    Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (2212) and (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (2223) superconductors have orthorhombic crystal structures. They form platelike grains that at high temperatures grow primarily in the a-b planes and not in the c direction. The diffusional properties of Bi-Sr-Ca-Cu-O superconductors are so anisotropic that 2212 and 2223 cannot, in general, be densified by solid-state sintering. Improved densification can be achieved by application of pressure or by use of transient liquid phases. Most useful bulk Bi-Sr-Ca-Cu-O superconductors are composites that contain Ag. The Ag lowers the melting points of the superconductors, which has significant effects on microstructural development. The results of disparate sintering studies are presented and discussed.

  13. Sintering of bulk high-{Tc} superconductors: Bi-Sr-Ca-Cu-O

    SciTech Connect

    Goretta, K.C.; Lanagan, M.T.; Kaufman, D.Y.; Biondo, A.C.; Wu, C.T.; Loomans, M.E.; Cheesman, M.R.; Poeppel, R.B.; Nash, A.S.

    1992-05-01

    Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (2212) and (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (2223) superconductors have orthorhombic crystal structures. They form platelike grains that at high temperatures grow primarily in the a-b planes and not in the c direction. The diffusional properties of Bi-Sr-Ca-Cu-O superconductors are so anisotropic that 2212 and 2223 cannot, in general, be densified by solid-state sintering. Improved densification can be achieved by application of pressure or by use of transient liquid phases. Most useful bulk Bi-Sr-Ca-Cu-O superconductors are composites that contain Ag. The Ag lowers the melting points of the superconductors, which has significant effects on microstructural development. The results of disparate sintering studies are presented and discussed.

  14. 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.

  15. The Reliability of Microalloyed Sn-Ag-Cu Solder Interconnections Under Cyclic Thermal and Mechanical Shock Loading

    NASA Astrophysics Data System (ADS)

    Mattila, Toni T.; Hokka, Jussi; Paulasto-Kröckel, Mervi

    2014-11-01

    In this study, the performance of three microalloyed Sn-Ag-Cu solder interconnection compositions (Sn-3.1Ag-0.52Cu, Sn-3.0Ag-0.52Cu-0.24Bi, and Sn-1.1Ag-0.52Cu-0.1Ni) was compared under mechanical shock loading (JESD22-B111 standard) and cyclic thermal loading (40 ± 125°C, 42 min cycle) conditions. In the drop tests, the component boards with the low-silver nickel-containing composition (Sn-Ag-Cu-Ni) showed the highest average number of drops-to-failure, while those with the bismuth-containing alloy (Sn-Ag-Cu-Bi) showed the lowest. Results of the thermal cycling tests showed that boards with Sn-Ag-Cu-Bi interconnections performed the best, while those with Sn-Ag-Cu-Ni performed the worst. Sn-Ag-Cu was placed in the middle in both tests. In this paper, we demonstrate that solder strength is an essential reliability factor and that higher strength can be beneficial for thermal cycling reliability but detrimental to drop reliability. We discuss these findings from the perspective of the microstructures and mechanical properties of the three solder interconnection compositions and, based on a comprehensive literature review, investigate how the differences in the solder compositions influence the mechanical properties of the interconnections and discuss how the differences are reflected in the failure mechanisms under both loading conditions.

  16. Syntheses and crystal structures of new chain-containing iodometallate compounds: [H1,10-phen](H 2O) 1.41[AgI 2], [H1,10-phen](H 2O) 1.42[CuI 2]; [Co(tpy) 2][Bi 2I 8], [Fe(tpy) 2][Bi 2I 8]; [Co(1,10-phen) 3][Pb 3I 8]·H 2O, and [Fe(1,10-phen) 3][Pb 3I 8]·0.5(H 2O)

    NASA Astrophysics Data System (ADS)

    Tershansy, Meredith A.; Goforth, Andrea M.; Peterson, LeRoy; Burns, M. C.; Smith, Mark D.; zur Loye, Hans-Conrad

    2007-10-01

    Three pairs of novel, isostructural polymeric iodometallate compounds, [H1,10-phen](H 2O) 1.41[AgI 2] ( 1) ([H1,10-phen] + = [1,10-phenanthrolinium] +), [H1,10-phen](H 2O) 1.42[CuI 2] ( 2), [Co(tpy) 2][Bi 2I 8] ( 3) (tpy = 2,2':6'2″-terpyridine), [Fe(tpy) 2][Bi 2I 8] ( 4), [Co(1,10-phen) 3][Pb 3I 8]·H 2O ( 5) (1,10-phen = 1,10-phenanthroline), and [Fe(1,10-phen) 3][Pb 3I 8]·0.5(H 2O) ( 6) have been synthesized solvothermally and characterized by single crystal X-ray diffraction. Compounds 1 and 2 are isostructural and crystallize in the orthorhombic space group Cmma with lattice parameters of a = 6.7063(7) Å, b = 17.6051(18) Å, c = 12.7088(13) Å and a = 6.5770(3) Å, b = 17.5245(8) Å, c = 12.5515(6) Å, respectively. The polymeric anionic chains in 1 and 2 are formed by edge-sharing MI 4 (M = Ag, Cu) tetrahedra. Compounds 3 and 4 are isostructural and crystallize in the monoclinic space group P2 1/ n with lattice parameters of a = 16.5085(7) Å, b = 16.0392(7) Å, c = 16.5115(7) Å, β = 97.4710(10)° and a = 16.4478(6) Å, b = 16.0645(6) Å, c = 16.4498(6) Å, β = 97.4490(10)°, respectively. Both structures contain the first observed, face-sharing [Bi 2I 8] 2- anion cluster that is linked via corner sharing into infinite zig-zag anionic chains. Compounds 5 and 6 are isostructural and crystallize in the triclinic space group P1¯ with lattice parameters of a = 11.8798(5) Å, b = 15.2805(7) Å, c = 16.1889(7) Å, α = 63.9240(10)°, β = 74.0420(10)°, γ = 73.2540(10)° and a = 11.7889(5) Å, b = 15.3224(6) Å, c = 16.2584(6) Å, α = 64.1920(10)°, β = 73.5600(10)°, and γ = 73.7120(10)°, respectively. Compounds 5 and 6 contain infinite [Pb 3I 8] 2- chains in which the three crystallographically unique Pb 2+ ions are found in sets of three trans face-sharing octahedra. These face-sharing trimers are observed in pairs that share three edges, and the pairs are further connected into 1-D chains by edge sharing with neighboring 2 × 3 units.

  17. Exploratory Bi-Factor Analysis

    ERIC Educational Resources Information Center

    Jennrich, Robert I.; Bentler, Peter M.

    2011-01-01

    Bi-factor analysis is a form of confirmatory factor analysis originally introduced by Holzinger. The bi-factor model has a general factor and a number of group factors. The purpose of this article is to introduce an exploratory form of bi-factor analysis. An advantage of using exploratory bi-factor analysis is that one need not provide a specific…

  18. Positive selection of self-antigen-specific CD8+ T cells by hematopoietic cells.

    PubMed

    Yamada, Hisakata; Shibata, Kensuke; Sakuraba, Koji; Fujimura, Kenjiro; Yoshikai, Yasunobu

    2013-08-01

    In contrast to thymic epithelial cells, which induce the positive selection of conventional CD8(+) T cells, hematopoietic cells (HCs) select innate CD8(+) T cells whose Ag specificity is not fully understood. Here we show that CD8(+) T cells expressing an H-Y Ag-specific Tg TCR were able to develop in mice in which only HCs expressed MHC class I, when HCs also expressed the H-Y Ag. These HC-selected self-specific CD8(+) T cells resemble innate CD8(+) T cells in WT mice in terms of the expression of memory markers and effector functions, but are phenotypically distinct from the thymus-independent CD8(+) T-cell population. The peripheral maintenance of H-Y-specific CD8(+) T cells required presentation of the self-Ag and IL-15 on HCs. HC-selected CD8(+) T cells in mice lacking the Tg TCR also showed these features. Furthermore, by using MHC class I tetramers with a male Ag peptide, we found that self-Ag-specific CD8(+) T cells in TCR non-Tg mice could develop via HC-induced positive selection, supporting results obtained from H-Y TCR Tg mice. These findings indicate the presence of self-specific CD8(+) T cells that are positively selected by HCs in the peripheral T-cell repertoire. PMID:23636825

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

    SciTech Connect

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

    2014-04-01

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

  20. Characterization of CdS thin film in high efficient CdS/CdTe solar cells

    NASA Astrophysics Data System (ADS)

    Tsuji, Miwa; Aramoto, Tetsuya; Ohyama, Hideaki; Hibino, Takeshi; Omura, Kuniyoshi

    2000-06-01

    Cadmium sulfide (CdS) thin film is the most commonly used window material for high-efficient cadmium telluride (CdTe) thin-film photovoltaic devices. High-efficient CdS/CdTe solar cells have been developed using ultra-thin CdS films having a thickness of below 0.1 μm. CdS film is deposited on transparent conductive oxide (TCO) film coated glass substrates by the metal organic chemical vapor deposition (MOCVD) technique, CdTe film is subsequently deposited by the close-spaced sublimation (CSS) technique. Finally, carbon and Ag-In electrodes are fabricated by the screen printing and sintering method. Cell performance depends primarily on the electrical and optical properties of CdS film, and hence we started to develop higher quality CdS film and found out clear differences between high- and low-quality CdS films from various analyses: SEM, AFM, SIMS, TDS and FT-IR. As a result of controlling qualities of CdS films, photovoltaic conversion efficiency of 10.5% has been achieved for a size of 1376 cm 2 of the solar module under air mass (AM) 1.5 conditions by the Japan Quality Assurance Organization (JQA).

  1. The Synthesis of Ag-Doped Mesoporous TiO2

    SciTech Connect

    Li, Xiaohong S.; Fryxell, Glen E.; Wang, Chong M.; Engelhard, Mark H.

    2008-04-15

    Ag-doped mesoporous titanium oxide was prepared using non-ionic surfactants and easily handled titanium precursors, under mild reaction conditions. In contrast to the stabilizing effect of Cd-doping on mesoporous TiO2, Ag-doping was found to significantly destabilize the mesoporous structure.

  2. CD Recorders.

    ERIC Educational Resources Information Center

    Falk, Howard

    1998-01-01

    Discussion of CD (compact disc) recorders describes recording applications, including storing large graphic files, creating audio CDs, and storing material downloaded from the Internet; backing up files; lifespan; CD recording formats; continuous recording; recording software; recorder media; vulnerability of CDs; basic computer requirements; and…

  3. CD Rainbows

    ERIC Educational Resources Information Center

    Ouseph, P. J.

    2007-01-01

    Several papers have been published on the use of a CD as a grating for undergraduate laboratories and/or for high school and college class demonstrations. Four years ago "The Physics Teacher" had a spectacular cover picture showing emission spectrum as viewed through a CD with no coating. That picture gave the impetus to develop a system that can…

  4. 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

  5. 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.

  6. Resistive switching properties in CdZnTe films

    SciTech Connect

    Zha, Gangqiang; Lin, Yun; Tan, Tingting; Jie, Wanqi; Zeng, Dongmei

    2015-02-09

    The ternary II–VI compound semiconductor cadmium zinc telluride (CdZnTe) has bi-stable conduction characteristics. In this letter, CdZnTe films are grown on indium tin oxide (ITO) substrates by radio frequency magnetron sputtering. The current-voltage characteristics show that there is resistive switching in a structure consisting of an 800-nm-thick CdZnTe film, an Au Schottky contact, and an ITO bottom electrode. The electroresistance in Au/CdZnTe/ITO may be related to the polarization of the CdZnTe film and the Schottky contact.

  7. Dendritic Cell Migration and Antigen Presentation Are Coordinated by the Opposing Functions of the Tetraspanins CD82 and CD37.

    PubMed

    Jones, Eleanor L; Wee, Janet L; Demaria, Maria C; Blakeley, Jessica; Ho, Po Ki; Vega-Ramos, Javier; Villadangos, Jose A; van Spriel, Annemiek B; Hickey, Michael J; Hämmerling, Günther J; Wright, Mark D

    2016-02-01

    This study supports a new concept where the opposing functions of the tetraspanins CD37 and CD82 may coordinate changes in migration and Ag presentation during dendritic cell (DC) activation. We have previously published that CD37 is downregulated upon monocyte-derived DC activation, promotes migration of both skin and bone marrow-derived dendritic cells (BMDCs), and restrains Ag presentation in splenic and BMDCs. In this article, we show that CD82, the closest phylogenetic relative to CD37, appears to have opposing functions. CD82 is upregulated upon activation of BMDCs and monocyte-derived DCs, restrains migration of skin and BMDCs, supports MHC class II maturation, and promotes stable interactions between T cells and splenic DCs or BMDCs. The underlying mechanism involves the rearrangement of the cytoskeleton via a differential activation of small GTPases. Both CD37(-/-) and CD82(-/-) BMDCs lack cellular projections, but where CD37(-/-) BMDCs spread poorly on fibronectin, CD82(-/-) BMDCs are large and spread to a greater extent than wild-type BMDCs. At the molecular level, CD82 is a negative regulator of RhoA, whereas CD37 promotes activation of Rac-1; both tetraspanins negatively regulate Cdc42. Thus, this study identifies a key aspect of DC biology: an unactivated BMDC is CD37(hi)CD82(lo), resulting in a highly motile cell with a limited ability to activate naive T cells. By contrast, a late activated BMDC is CD37(lo)CD82(hi), and thus has modified its migratory, cytoskeletal, and Ag presentation machinery to become a cell superbly adapted to activating naive T cells. PMID:26729805

  8. Performance of Graphite Pastes Doped with Various Materials as Back Contact for CdS/CdTe Solar Cell

    NASA Astrophysics Data System (ADS)

    Hanafusa, Akira; Aramoto, Tetsuya; Morita, Akikatsu

    2001-12-01

    To date the problem of developing a suitable back contact for CdS/CdTe solar cells has yet to be resolved. The Cu-doped graphite paste that is widely used as a back contact is associated with degradation problems due to possible Cu diffusion across the CdS/CdTe junction. This study was designed to find ways to improve the graphite paste for superior electrical contacts. Mixtures of graphite paste with various material constituents and dopants consisting of silver-, lead-, nickel-, antimony-, bismuth-, or phosphor-based compounds, were studied. Results show that the performances of solar cells fabricated from these graphite pastes vary with the change in the composition. In the cases of Ag2Te and Ni2P, we studied their relationship with the solar cell characteristics with regard to dopant quantity, and furthermore in the case of Ag2Te, with regard to the sintering temperature of the graphite electrode. A fill factor (F.F.) of over 0.65 and efficiencies over 13% were obtained with Ag2Te, Ag3PO4, Ag2MoO4, and NiTe, and efficiencies over 12% were obtained with AgF, AgCl, Ni2P, and Ni3P.

  9. 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.

  10. Selective decrease of CD26 expression in T cells from HIV-1-infected individuals.

    PubMed

    Blazquez, M V; Madueño, J A; Gonzalez, R; Jurado, R; Bachovchin, W W; Peña, J; Muñoz, E

    1992-11-01

    The decrease of CD4+ cells in AIDS patients is widely documented, although the selective loss within different subsets of CD4+ cells and the mechanisms involved in this phenomenon are controversial. In the present report we have analyzed the proliferative response to Ag and mitogen of peripheral blood T lymphocytes from HIV-infected individuals, the phenotype profile of CD26+ and CD26- subset of cells and their infectivity by the HIV. The expression of CD26 Ag, either in CD4+ or CD8+ cells, was clearly diminished in all the patients tested. On the other hand, the expression of CD29 seems not to be affected, nevertheless T cells from these patients were unable to generate a proliferative response against soluble Ag. In 11 out of 13 patients, polymerase chain reaction studies demonstrated that the CD26- subset of CD4+ cells was the main reservoir for HIV-1 in infected individuals and HIV-1 virus preferentially infected in vitro CD4+/CD26- subpopulation. This capacity for preferential infectivity, together with the selective loss of cells expressing CD26 Ag, helps to explain the progressive impairment in the immune system of these patients and sheds new light on our understanding of the AIDS pathophysiology. PMID:1357035

  11. Pirquitasite, Ag2ZnSnS4

    PubMed Central

    Schumer, Benjamin N.; Downs, Robert T.; Domanik, Kenneth J.; Andrade, Marcelo B; Origlieri, Marcus J.

    2013-01-01

    Pirquitasite, ideally Ag2ZnSnS4 (disilver zinc tin tetra­sulfide), exhibits tetra­gonal symmetry and is a member of the stannite group that has the general formula A2BCX 4, with A = Ag, Cu; B = Zn, Cd, Fe, Cu, Hg; C = Sn, Ge, Sb, As; and X = S, Se. In this study, single-crystal X-ray diffraction data are used to determine the structure of pirquitasite from a twinned crystal from the type locality, the Pirquitas deposit, Jujuy Province, Argentina, with anisotropic displacement parameters for all atoms, and a measured composition of (Ag1.87Cu0.13)(Zn0.61Fe0.36Cd0.03)SnS4. One Ag atom is located on Wyckoff site Wyckoff 2a (symmetry -4..), the other Ag atom is statistically disordered with minor amounts of Cu and is located on 2c (-4..), the (Zn, Fe, Cd) site on 2d (-4..), Sn on 2b (-4..), and S on general site 8g. This is the first determination of the crystal structure of pirquitasite, and our data indicate that the space group of pirquitasite is I-4, rather than I-42m as previously suggested. The structure was refined under consideration of twinning by inversion [twin ratio of the components 0.91 (6):0.09 (6)]. PMID:23424398

  12. Enhancement of critical currents in (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) superconducting tapes.

    SciTech Connect

    Balachandran, U.

    1998-11-11

    The performance of (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} (Bi-2223) superconducting tapes in magnetic fields at 77 K is critical for winding this material into high-field magnets. We have recently enhanced the transport current (I{sub c}) of multifilament Ag-clad Bi-2223 tapes in a self-field at 77 K by increasing the packing density of the precursor powder improving the mechanical deformation, optimizing the conductor design, and adjusting the cooling rate. I{sub c} values of >40 A were obtained repeatedly. However, a transport current of 42 A in a self-field declined to 4 A in a 0.2 T magnetic field applied parallel to the c-axis at 77 K. A new composite tape was then fabricated in which a YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (Y-123) film was deposited on the top of the Ag-sheathed Bi-2223 tape to shield the applied magnetic field and protect the central Bi-2223 filaments. Magnetization measurements showed that the critical current densities of the Y-123-coated, Ag-sheathed Bi-2223 tapes were higher than those of an uncoated tape. These preliminary results may provide the basis for further improving the processing of long-length Bi-2223 tapes for high-field applications.

  13. Hydride generation-resonance Rayleigh scattering and SERS spectral determination of trace Bi.

    PubMed

    Liang, Xiaojing; Wen, Guiqing; Liu, Qingye; Liang, Aihui; Jiang, Zhiliang

    2016-09-01

    In acidic solutions, Bi(III) was reduced by NaBH4 to form BiH3 gas. Using I3(-)graphene oxide (GO) as absorption solution, the BiH3 gas reacted with I3(-) to form I(-) that resulted in the I3(-) concentration decreasing. In the absence of BiH3, the I3(-) concentration was high, and as receptors it was closed to the surfaces of GO which was as donors. Then the surface plasmon resonance Rayleigh scattering (RRS) energy of GO transfers to I3(-) heavily, and results in the RRS quenching severely. With the increase of the Bi(III) concentration, the receptors and the RRS energy transfer (RRS-ET) decreased, so the RRS intensity enhanced linearly at 370nm. The RRS intensity was linear to the Bi(III) concentration in 0.05-5.5μmol/L, with a detection limit of 4ng/mL Bi. A new RRS-ET spectral method was developed for the determination of trace Bi(III). Using I3(-) as the absorption solution, silver nanorod (AgNR) as sol substrate and Vitoria blue B (VBB) as molecular probe, a SERS method was developed for detection of Bi. PMID:27214274

  14. Hydride generation-resonance Rayleigh scattering and SERS spectral determination of trace Bi

    NASA Astrophysics Data System (ADS)

    Liang, Xiaojing; Wen, Guiqing; Liu, Qingye; Liang, Aihui; Jiang, Zhiliang

    2016-09-01

    In acidic solutions, Bi(III) was reduced by NaBH4 to form BiH3 gas. Using I3- graphene oxide (GO) as absorption solution, the BiH3 gas reacted with I3- to form I- that resulted in the I3- concentration decreasing. In the absence of BiH3, the I3- concentration was high, and as receptors it was closed to the surfaces of GO which was as donors. Then the surface plasmon resonance Rayleigh scattering (RRS) energy of GO transfers to I3- heavily, and results in the RRS quenching severely. With the increase of the Bi(III) concentration, the receptors and the RRS energy transfer (RRS-ET) decreased, so the RRS intensity enhanced linearly at 370 nm. The RRS intensity was linear to the Bi(III) concentration in 0.05-5.5 μmol/L, with a detection limit of 4 ng/mL Bi. A new RRS-ET spectral method was developed for the determination of trace Bi(III). Using I3- as the absorption solution, silver nanorod (AgNR) as sol substrate and Vitoria blue B (VBB) as molecular probe, a SERS method was developed for detection of Bi.

  15. A tetravalent bispecific TandAb (CD19/CD3), AFM11, efficiently recruits T cells for the potent lysis of CD19+ tumor cells

    PubMed Central

    Reusch, Uwe; Duell, Johannes; Ellwanger, Kristina; Herbrecht, Carmen; Knackmuss, Stefan HJ; Fucek, Ivica; Eser, Markus; McAleese, Fionnuala; Molkenthin, Vera; Le Gall, Fabrice; Topp, Max; Little, Melvyn; Zhukovsky, Eugene A

    2015-01-01

    To harness the potent tumor-killing capacity of T cells for the treatment of CD19+ malignancies, we constructed AFM11, a humanized tetravalent bispecific CD19/CD3 tandem diabody (TandAb) consisting solely of Fv domains. The molecule exhibits good manufacturability and stability properties. AFM11 has 2 binding sites for CD3 and 2 for CD19, an antigen that is expressed from early B cell development through differentiation into plasma cells, and is an attractive alternative to CD20 as a target for the development of therapeutic antibodies to treat B cell malignancies. Comparison of the binding and cytotoxicity of AFM11 with those of a tandem scFv bispecific T cell engager (BiTE) molecule targeting the same antigens revealed that AFM11 elicited more potent in vitro B cell lysis. Though possessing high affinity to CD3, the TandAb mediates serial-killing of CD19+ cells with little dependence of potency or efficacy upon effector:target ratio, unlike the BiTE. The advantage of the TandAb over the BiTE was most pronounced at lower effector:target ratios. AFM11 mediated strictly target-dependent T cell activation evidenced by CD25 and CD69 induction, proliferation, and cytokine release, notwithstanding bivalent CD3 engagement. In a NOD/scid xenograft model, AFM11 induced dose-dependent growth inhibition of Raji tumors in vivo, and radiolabeled TandAb exhibited excellent localization to tumor but not to normal tissue. After intravenous administration in mice, half-life ranged from 18.4 to 22.9 h. In a human ex vivo B-cell chronic lymphocytic leukemia study, AFM11 exhibited substantial cytotoxic activity in an autologous setting. Thus, AFM11 may represent a promising therapeutic for treatment of CD19+ malignancies with an advantageous safety risk profile and anticipated dosing regimen. PMID:25875246

  16. Two-dimensional peridynamic simulation of the effect of defects on the mechanical behavior of Bi2Sr2CaCu2Ox round wires

    NASA Astrophysics Data System (ADS)

    Le, Q. V.; Chan, W. K.; Schwartz, J.

    2014-11-01

    Ag/AgX sheathed Bi2Sr2CaCu2Ox (Bi2212) is the only superconducting round wire (RW) with high critical current density (Jc) at high magnetic (>25 T) and is thus a strong candidate for high field magnets for nuclear magnetic resonance and high energy physics. A significant remaining challenge, however, is the relatively poor electromechanical behavior of Bi2212 RW, yet there is little understanding of the relationships between the internal Bi2212 microstructure and the mechanical behavior. This is in part due to the complex microstructures within the Bi2212 filaments and the uncertain role of interfilamentary bridges. Here, two-dimensional peridynamic simulations are used to study the stress distribution of the Bi2212 RWs under an axial tensile load. The simulations use scanning electron micrographs obtained from high Jc wires as a starting point to study the impact of various defects on the distribution of stress concentration within the Bi2212 microstructure and Ag. The flexibility of the peridynamic approach allows various defects, including those captured from SEM micrographs and artificially created defects, to be inserted into the microstructure for systematic study. Furthermore, this approach allows the mechanical properties of the defects to be varied, so the effects of porosity and both soft and hard secondary phases are evaluated. The results show significant stress concentration around defects, interfilamentary bridges and the rough Bi2212/Ag interface. In general, the stress concentration resulting from porosity is greater than that of solid-phase inclusions. A clear role of the defect geometry is observed. Results indicate that crack growth is likely to initiate at the Ag/Bi2212 interface or at voids, but that voids may also arrest crack growth in certain circumstances. These results are consistent with experimental studies of Bi2212 electromechanical behavior and magneto-optical imaging of crack growth.

  17. T Cell-Extrinsic CD18 Attenuates Antigen-Dependent CD4+ T cell Activation In Vivo1

    PubMed Central

    Wu, Xingxin; Lahiri, Amit; Sarin, Ritu; Abraham, Clara

    2015-01-01

    The β2 integrins (CD11/CD18) are heterodimeric leukocyte adhesion molecules expressed on hematopoietic cells. The role of T cell-intrinsic CD18 in trafficking of naïve T cells to secondary lymphoid organs, and in antigen-dependent T cell activation in vitro and in vivo has been well-defined. However, the T cell-extrinsic role for CD18, including on antigen presenting cells (APC), in contributing to T cell activation in vivo is less well understood. We examined the role for T cell-extrinsic CD18 in the activation of WT CD4+ T cells in vivo through the adoptive transfer of DO11.10 Ag-specific CD4+ T cells into CD18−/− mice. We found that T cell-extrinsic CD18 was required for attenuating OVA-induced T cell proliferation in peripheral lymph nodes (PLN). The increased proliferation of WT DO11.10 CD4+ T cells in CD18−/− PLN was associated with a higher percentage of APC, and these APC demonstrated an increased activation profile and increased Ag-uptake, in particular in F4/80+ APC. Depletion of F4/80+ cells both reduced and equalized antigen-dependent T cell proliferation in CD18−/− relative to littermate control PLN, demonstrating that these cells play a critical role in the enhanced T cell proliferation in CD18−/− mice. Consistently, CD11b blockade, which is expressed on F4/80+ macrophages, enhanced the proliferation of DO11.10+ T cells in CD18+/− PLN. Thus, in contrast to the T cell-intrinsic essential role for CD18 in T cell activation, T cell-extrinsic expression of CD18 attenuates antigen-dependent CD4+ T cell activation in PLN in vivo. PMID:25801431

  18. Superconducting and Mechanical Properties of Bi-2223/Metal Alloy Wires Composite Bulk

    NASA Astrophysics Data System (ADS)

    Yoshizawa, S.; Hirano, S.; Oya-Seimiya, Y.; Hishinuma, Y.; Nishimura, A.

    2006-03-01

    Bi-2223 sintered bulk samples with addition of AgMg wires or Ag-plated Ni wires have been prepared to improve both the superconducting and the mechanical properties, simultaneously. When 24 AgMg wires of 0.4 mm in diameter were added into Bi-2223 bulk composite sample, the critical current density (Jc) at 77 K increased from 2 A/mm2 to 7 A/mm2. The mechanical properties have been estimated by a three-point bending test. The maximum bending stress of 70 - 90 MPa at the rupture was obtained for Bi-2223/metal wires composite bulk, regardless of the number of the wires. After the maximum bending stress, Bi-2223 bulk without metal wires fractured separately, while the composite did not fracture but fine cracks were induced only. The Jc values of the composites just after the fracture were about half of the Jc value in the composites without bending. It has been observed that the superconducting current flows even after cracking, in Bi-2223 bulk with metal wires. This is due to the fact that metal wires suppress progress of fine cracks just after the fracture, while the superconducting current flows in the uncracked region. This current still remaining after the fracture is a very important feature for the applications.

  19. High Bi content GaSbBi alloys

    NASA Astrophysics Data System (ADS)

    Rajpalke, M. K.; Linhart, W. M.; Birkett, M.; Yu, K. M.; Alaria, J.; Kopaczek, J.; Kudrawiec, R.; Jones, T. S.; Ashwin, M. J.; Veal, T. D.

    2014-07-01

    The epitaxial growth, structural, and optical properties of GaSb1-xBix alloys have been investigated. The Bi incorporation into GaSb is varied in the range 0 < x ≤ 9.6% by varying the growth rate (0.31-1.33 μm h-1) at two growth temperatures (250 and 275 °C). The Bi content is inversely proportional to the growth rate, but with higher Bi contents achieved at 250 than at 275 °C. A maximum Bi content of x = 9.6% is achieved with the Bi greater than 99% substitutional. Extrapolating the linear variation of lattice parameter with Bi content in the GaSbBi films enabled a zinc blende GaBi lattice parameter to be estimated of 6.272 Å. The band gap at 300 K of the GaSbBi epitaxial layers decreases linearly with increasing Bi content down to 410 ± 40 meV (3 μm) for x = 9.6%, corresponding to a reduction of ˜35 meV/%Bi. Photoluminescence indicates a band gap of 490 ± 5 meV at 15 K for x = 9.6%.

  20. Growth of Nucleation Sites on Pd-doped Bi_2Sr_2Ca1 Cu_2O_8+δ

    NASA Astrophysics Data System (ADS)

    Kouzoudis, D.; Finnemore, D. K.; Xu, Ming; Balachandran

    1996-03-01

    Enviromental Scanning Electron Microscope has shown evidence that during the growth of Bi_2Sr_2Ca_2Cu_3O_10+δ from mixed powders of Pb-doped Bi_2Sr_2Ca_1Cu_2O_8+δ and other oxides, a dense array of hillocks or mesas grow at the interface between an Ag overlay and Pb doped Bi_2Sr_2Ca_1Cu_2O_8+δ grains. These hillocks develop a texture that looks like ''chicken pox'' during the ramp up to the reaction temperature starting at about 700^circ C and they are about 500 to 1000 nm across and are spaced at about 500 to 1000 nm. If there is no Ag, this texture does not develop. Preliminary measurments indicate that the hillocks are re-crystallization of (Bi,Pb)_2Sr_2Ca_1Cu_2O_8+δ and are definetely not a Pb rich phase

  1. BI Project Success

    ERIC Educational Resources Information Center

    Tracey, Graham; Riha, James

    2009-01-01

    Managing business intelligence (BI) projects in higher education is a formidable responsibility that challenges even the most experienced technical project managers. Data source dependencies, uncertain data quality, changing information requirements, and urgency for actionable information are but a few examples among the multitude of challenges.…

  2. Aqueous synthesis of CdTe at FeOOH and CdTe at Ni(OH){sub 2} composited nanoparticles

    SciTech Connect

    Li Liang; Ren Jicun . E-mail: Jicunren@sjtu.edu.cn

    2006-06-15

    Two kinds of bi-functional nanomaterials, CdTe at FeOOH and CdTe at Ni(OH){sub 2}, were synthesized in water phase. In the synthesis, using the luminescent CdTe nanocrystals (NCs) as a core, Fe{sup 3+} (Ni{sup 2+}) was added to CdTe NCs aqueous solution and slowly hydrolyzed to deposit a layer of hydroxide onto the luminescent CdTe NCs in the presence of stabilizer. TEM, XRD, XPS, UV, fluorescence spectrometer and physical property measurement system (PPMS) were used to characterize the final products, and the results showed that the as-prepared nanoparticles with core/shell structure exhibited certain magnetic properties and fluorescence. - Graphical abstract: Fluorescent and magnetic bi-functional CdTe at FeOOH and CdTe at Ni(OH){sub 2} nanoparticles were prepared by seed-mediated approach in water phase.

  3. Gold enrichment and Bi-mineral assemblages in ores: Examples from shield and orogenic areas

    NASA Astrophysics Data System (ADS)

    Ciobanu, C. L.; Cook, N. J.; Pring, A.

    2003-04-01

    Gold deposits in metamorphic terranes, like their counterparts in hydrothermal areas, commonly contain small quantities of Bi-tellurides/selenides (BTS) or Bi-sulpho-salts (Bi-ss). These mineral groups, although eclectic in character, have the potential to offer real and hitherto-untapped information on processes of ore formation and evolution, since BTS speciation, paragenesis and assemblages lie at the heart of ideas covering mechanisms of Au-enrichment, fluid-driven infiltration and sulphide modularity. A systematic study of the distribution of BTS in Au-enriched ores from 25 deposits in the Fennoscandian/Ukrainian Shields and in European Phanerozoic orogenic belts allows comparison of telluride speciation and association and construction of a qualitative diagram for Bi-telluride stability in fS_2-fO_2 space on the basis of Bi/Te+Se+S (R{Bi/Te}). Tsumoite (BiTe) stability separates reducing environ-ments where Bi-tellurides with R{Bi/Te}>1 are associated with native Bi and maldonite, and oxidizing environments where Bi-tellurides with R{Bi/Te}<1 are associated with Au-Ag-bearing tellurides and native Te. BTS are closely associated with Au, due to incorporation within Bi{melt} above 271^oC. Such melts are powerful "scavengers" for Au, especially at the main fS_2/fO_2 buffers. Overall compositions of Bi-Te-Se-Aumelts, as seen in resultant BTS associations, reflect the reducing/oxidizing character of source fluids. Telluride speciation has implications for discriminating overprinting events, with focus on local Au-enrichment at metamorphic peaks, during retrograde stages in skarn and secondary boiling in porphyry, irrespective of age or deposit type. Unlike tellurides, Bi-ss are not necessarily genetically related to Au-enrich-ment. Instead, speciation and compositional variation relate to primary fluid sources and may be specific to regional/orefield trends. Nevertheless, as many sulphosalts form polysomatic series, they can adjust chemical variation via

  4. Longitudinal Requirement for CD4+ T Cell Help for Adenovirus Vector–Elicited CD8+ T Cell Responses

    PubMed Central

    Provine, Nicholas M.; Larocca, Rafael A.; Penaloza-MacMaster, Pablo; Borducchi, Erica N.; McNally, Anna; Parenteau, Lily R.; Kaufman, David R.

    2014-01-01

    Despite the widespread use of replication-incompetent recombinant adenovirus (Ad) vectors as candidate vaccine platforms, the mechanism by which these vectors elicit CD8+ T cell responses remains poorly understood. Our data demonstrate that induction and maintenance of CD8+ T cell responses by Ad vector immunization is longitudinally dependent on CD4+ T cell help for a prolonged period. Depletion of CD4+ T cells in wild type mice within the first 8 d following Ad immunization resulted in dramatically reduced induction of Ag-specific CD8+ T cells, decreased T-bet and eomesodermin expression, impaired KLRG1+ effector differentiation, and atypical expression of the memory markers CD127, CD27, and CD62L. Moreover, these CD8+ T cells failed to protect against a lethal recombinant Listeria monocytogenes challenge. Depletion of CD4+ T cells between weeks 1 and 4 following immunization resulted in increased contraction of memory CD8+ T cells. These data demonstrate a prolonged temporal requirement for CD4+ T cell help for vaccine-elicited CD8+ T cell responses in mice. These findings have important implications in the design of vaccines aimed at eliciting CD8+ T cell responses and may provide insight into the impaired immunogenicity of vaccines in the context of AIDS and other CD4+ T cell immune deficiencies. PMID:24778441

  5. In situ observation of 2212 intergrowths in the early stages of (Bi, Pb)2223 phase formation using the synchrotron XRD technique

    NASA Astrophysics Data System (ADS)

    Nakao, Fumitake; Osamura, Kozo

    2005-04-01

    2212 intergrowths in the (Bi, Pb)2223 phase have been investigated using in situ high temperature synchrotron XRD technique. With a high energy synchrotron x-ray and high resolution diffractometer, we could obtain high resolution powder XRD patterns of (Bi, Pb)2223 and (Bi, Pb)2212 from the whole bulk inside the Ag-sheath. This gave us more detailed information on 2212 intergrowths in the (Bi, Pb)2223 phase than ever before. During in situ observation, the Ag-tubed precursor was kept at 1095 K with flowing Ar-7.8% O2 mixed gas. The profiles of the diffraction peaks were analysed by Rietveld analysis to evaluate the isotropic and anisotropic lattice strain of (Bi, Pb)2223 and (Bi, Pb)2212. Considering the evolution of anisotropic lattice strain during the heat treatment, it was concluded that 2212 intergrowths in the (Bi, Pb)2223 phase are not in the untransformed region of (Bi, Pb)2212 after incommensurate intercalation, but a stacking fault-like defect contained in the (Bi, Pb)2223 phase during its nucleation and growth. A new model of 2212 intergrowth formation in the (Bi, Pb)2223 phase was suggested and discussed.

  6. Tuning the composition of Bi x W y O nanorods towards zero bias PEC water splitting.

    PubMed

    Larson, Steven; Zhao, Yiping

    2016-06-24

    A unique co-oblique angle deposition method was used to create nanorod arrays of mixed phase Bi2O3/WO3/Bi2WO6 with varying atomic ratios of Bi to W. The effect of the tuning on the resulting nanostructures was characterized by EDX, SEM, XRD, optical transmission, specular reflection, and diffuse reflection spectroscopy. Samples with different Bi:W atomic ratio had a wide range of morphology and composition due to the surface mobility of deposited bismuth and its volume expansion during oxidation. Their photocatalytic and photoelectrochemical properties were investigated by methylene blue degradation and photo-generated current respectively. The sample with 38 at.% Bi showed the highest photodecay rates as well as the maximum photocurrent density, 4.3 μA cm(-2), at a bias potential of 600 mV versus Ag/AgCl (3M KCl); while the sample with 50 at.% Bi exhibited a high photocurrent density of 0.35 μA cm(-2) at zero bias potential, which indicates that varying the composition and mixed crystal phases of different oxides with appropriate band gaps and locations could hold the key to a visible light driven, zero bias potential, photoelectrochemical cell. PMID:27181626

  7. Tuning the composition of Bi x W y O nanorods towards zero bias PEC water splitting

    NASA Astrophysics Data System (ADS)

    Larson, Steven; Zhao, Yiping

    2016-06-01

    A unique co-oblique angle deposition method was used to create nanorod arrays of mixed phase Bi2O3/WO3/Bi2WO6 with varying atomic ratios of Bi to W. The effect of the tuning on the resulting nanostructures was characterized by EDX, SEM, XRD, optical transmission, specular reflection, and diffuse reflection spectroscopy. Samples with different Bi:W atomic ratio had a wide range of morphology and composition due to the surface mobility of deposited bismuth and its volume expansion during oxidation. Their photocatalytic and photoelectrochemical properties were investigated by methylene blue degradation and photo-generated current respectively. The sample with 38 at.% Bi showed the highest photodecay rates as well as the maximum photocurrent density, 4.3 μA cm‑2, at a bias potential of 600 mV versus Ag/AgCl (3M KCl); while the sample with 50 at.% Bi exhibited a high photocurrent density of 0.35 μA cm‑2 at zero bias potential, which indicates that varying the composition and mixed crystal phases of different oxides with appropriate band gaps and locations could hold the key to a visible light driven, zero bias potential, photoelectrochemical cell.

  8. Combination anti-CD137 and anti-CD40 antibody therapy in murine myc-driven hematological cancers.

    PubMed

    Westwood, Jennifer A; Matthews, Geoffrey M; Shortt, Jake; Faulkner, David; Pegram, Hollie J; Duong, Connie P M; Chesi, Marta; Bergsagel, P Leif; Sharp, Leslie L; Huhn, Richard D; Darcy, Phillip K; Johnstone, Ricky W; Kershaw, Michael H

    2014-08-01

    In order to stimulate antigen presentation and T cell activity against cancer, we treated three different tumor models in mice with the monoclonal antibodies anti-CD40 plus anti-CD137 (BiMab). In a subcutaneous transplantable MC38 colon cancer model, there was significant enhancement in the survival of mice following BiMab treatment. Anti-CD40 has shown considerable success against lymphoma in previous studies by other investigators, and we also showed in this study that, in a model of Eμ-Myc lymphoma, there was a statistically significant enhancement of survival of mice following BiMab treatment. Following the success of the BiMab treatment in the previous two models, we wished to determine if it would be successful in a mouse model of multiple myeloma. Firstly, we tested a transplantable model of disease in which multiple myeloma cells derived from Vk*MYC mice were injected intravenously. A minor proportion of anti-CD137 and BiMab treated mice experienced prolongation of life beyond 250 days. Then we tested the therapy in a spontaneously occurring multiple myeloma model, in Vk*MYC transgenic mice. The majority of mice treated survived longer than control mice, although statistical significance was not demonstrated. PMID:24934848

  9. Electronic structures of efficient MBiO3 (M = Li, Na, K, Ag) photocatalyst

    NASA Astrophysics Data System (ADS)

    Wen-Liu, Zhou; Zong-Yan, Zhao

    2016-03-01

    In order to deepen the understanding of the relationship between fundamental properties (including: microstructure and composition) and photocatalytic performance, four bismuthate compounds, including: LiBiO3, NaBiO3, KBiO3, and AgBiO3, are regarded as research examples in the present work, because they have particular crystal structures and similar compositions. Using density functional theory calculations, their structural, electronic, and optical properties are investigated and compared systematically. First of all, the calculated results of crystal structures and optical properties are in agreement with available published experimental data. Based on the calculated results, it is found that the tunneled or layered micro-structural properties lead to the stronger interaction between bismuth and oxygen, and the weaker interaction between alkaline-earth metal and [BiO6] octahedron, resulting in the feature of multi-band gaps in the cases of LiBiO3, NaBiO3, and KBiO3. This conclusion is supported by the case of AgBiO3, in which the feature of multi-band gaps disappears, due to the stronger interaction between the noble metal and [BiO6] octahedron. These properties have significant advantages in the photocatalytic performance: absorbing low energy photons, rapidly transferring energy carriers. Furthermore, the features of electronic structures of bismuthate compounds are well reflected by the absorption spectra, which could be confirmed by experimental measurements in practice. Combined with the calculated results, it could be considered that the crystal structures and compositions of the photocatalyst determine the electronic structures and optical properties, and subsequently determine the corresponding photocatalytic performance. Thus, a novel Bi-based photocatalyst driven by visible-light could be designed by utilizing specific compositions to form favorable electronic structures or specific micro-structures to form a beneficial channel for energy carriers

  10. Growth of CdS Nanorods and Deposition of Silver Nanoparticles.

    PubMed

    Zhao, Jie; Yang, Fanghong; Yang, Ping

    2015-05-01

    Systematic investigations have been done to deposit silver nanoparticles on seeded CdS nanorods. The CdS nanorods were synthesized by using CdS nanocrystals as seeds being indexed to the cubic structure (zinc-blende) and tetradecylphosphonic acid as surfactants to enable preferential growth on the reactive {001} facets. Ostwald ripening process occurred during the growth of CdS nanorods. Ag/CdS heterostructures were obtained through a facile method in which oleylamine was employed as reducing agents under an elevated temperature. Exposing CdS nanorods to Ag+ ions resulted in Ag domains depositing on the tips of the nanorods or defected sites embedding in the nanorod surfaces. Ag domains formed separate nuclei and grew quickly at a high concentration of AgNO3 solution. We further focused on discussing the morphology formation mechanism and optical properties of the heterostructures and the nanorods. The as-synthesized Ag/CdS heterostructures can facilitate charge separation at the metal-semiconductor interface. Herein, it opens up an application possibility of enhancing photocatalytic processes and other devices. PMID:26505026

  11. Isolation and Characterization of Salmonid CD4+ T Cells.

    PubMed

    Maisey, Kevin; Montero, Ruth; Corripio-Miyar, Yolanda; Toro-Ascuy, Daniela; Valenzuela, Beatriz; Reyes-Cerpa, Sebastián; Sandino, Ana María; Zou, Jun; Wang, Tiehui; Secombes, Christopher J; Imarai, Mónica

    2016-05-15

    This study reports the isolation and functional characterization of rainbow trout (Oncorhynchus mykiss) CD4-1(+) T cells and the establishment of an IL-15-dependent CD4-1(+) T cell line. By using Abs specific for CD4-1 and CD3ε it was possible to isolate the double-positive T cells in spleen and head kidney. The morphology and the presence of transcripts for T cell markers in the sorted CD4-1(+)CD3ε(+) cells were studied next. Cells were found to express TCRα, TCRβ, CD152 (CTLA-4), CD154 (CD40L), T-bet, GATA-3, and STAT-1. The sorted CD4-1(+) T cells also had a distinctive functional attribute of mammalian T lymphocytes, namely they could undergo Ag-specific proliferation, using OVA as a model Ag. The OVA-stimulated cells showed increased expression of several cytokines, including IFN-γ1, IL-4/13A, IL-15, IL-17D, IL-10, and TGF-β1, perhaps indicating that T cell proliferation led to differentiation into distinct effector phenotypes. Using IL-15 as a growth factor, we have selected a lymphoid cell line derived from rainbow trout head kidney cells. The morphology, cell surface expression of CD4-1, and the presence of transcripts of T cell cytokines and transcription factors indicated that this is a CD4-1(+) T cell line. To our knowledge, this is the first demonstration of the presence of CD4-1(+)CD3ε(+) T cells in salmonids. As in mammals, CD4-1(+) T cells may be the master regulators of immune responses in fish, and therefore these findings and the new model T cell line developed will contribute to a greater understanding of T cell function and immune responses in teleost fish. PMID:27053758

  12. High strength oxide dispersion strengthened silver aluminum alloys optimized for Bi2Sr2CaCu2O8+x round wire

    NASA Astrophysics Data System (ADS)

    Kajbafvala, Amir; Nachtrab, William; Kumar, Raj; Hunte, Frank; Wong, Terence; Schwartz, Justin

    2013-12-01

    High strength dispersion strengthened (DS) Ag/Al alloys with various Al content are studied as candidates for sheathing Bi2Sr2CaCu2O8+x (Bi2212) wire. The Ag/Al alloys are fabricated by powder metallurgy and internally oxidized in pure oxygen. The time and temperature of the internal oxidation heat treatment is varied to maximize the strength after undergoing the Bi2212 partial melt process (PMP). Vickers micro-hardness number (HVN), room temperature tensile behavior, optical and scanning electron microscopy, ion channeling contrast imaging using a focused ion beam and electrical resistivity measurements are used to characterize the alloys. An Ag/0.2wt%Mg (Ag/Mg) alloy is used for comparison. Results show that internal oxidation at 650-700  ° C for 4 h produces the highest HVN for the DS Ag/Al alloy; when oxidized at 675 ° C for 4 h the HVN, yield strength and tensile strength of the DS Ag/Al are 50% higher than the corresponding values of Ag/Mg. Microstructural observations show that Al2O3 precipitates play the main role in strengthening the DS Ag/Al alloy. The alloy retains its fine grain structure and strength after PMP heat treatment.

  13. Tetravalent anti-CD20/CD3 bispecific antibody for the treatment of B cell lymphoma.

    PubMed

    Lu, Chia-Yen; Chen, Gregory J; Tai, Pei-Han; Yang, Yu-Chen; Hsu, Yu-Shen; Chang, Mingi; Hsu, Chuan-Lung

    2016-05-13

    Bispecific antibodies (bsAbs) are second generation antibodies for therapeutic application in immunotherapy. One of the major strategies of the bsAb platform is the recruitment of immune effector T cells by incorporating an anti-CD3 domain. A bispecific T-cell engager (BiTE), with one end having an affinity for CD3 and the other end with affinity for CD19, has been approved in the US and Europe for the treatment of acute lymphoblastic leukemia. However, due to their small size and lack of Fc region, these single-chain variable fragment (scFv) bsAbs have short half-lives in vivo. Additionally, poor solubility, structural instability, and low production yields have also become major challenges in the bulk production process. To overcome these challenges, we have engineered a tetravalent bsAb with bivalent binding specificity for the CD20 and CD3 antigen in an immunoglobulin G (IgG) format. The fusion of the anti-CD3 scFvs to the CD20 antibody via a linker-hinge domain (LHD) results in improved antibody stabilization and properties. Here we demonstrate this antibody's highly efficient cancer cell elimination in a dose-dependent manner in a CD20-expressing B lymphoblastoid cell line in vitro. Our data suggest the potential clinical application of this bsAb for the treatment of CD20-expressing B cell malignancies. PMID:27040766

  14. Controllable synthesis of metal selenide heterostructures mediated by Ag2Se nanocrystals acting as catalysts.

    PubMed

    Zhou, Jiangcong; Huang, Feng; Xu, Ju; Wang, Yuansheng

    2013-10-21

    Ag2Se nanocrystals were demonstrated to be novel semiconductor mediators, or in other word catalysts, for the growth of semiconductor heterostructures in solution. This is a result of the unique feature of Ag2Se as a fast ion conductor, allowing foreign cations to dissolve and then to heterogrow the second phase. Using Ag2Se nanocrystals as catalysts, dimeric metal selenide heterostructures such as Ag2Se-CdSe and Ag2Se-ZnSe, and even multi-segment heterostructures such as Ag2Se-CdSe-ZnSe and Ag2Se-ZnSe-CdSe, were successfully synthesized. Several interesting features were found in the Ag2Se based heterogrowth. At the initial stage of heterogrowth, a layer of the second phase forms on the surface of an Ag2Se nanosphere, with a curved junction interface between the two phases. With further growth of the second phase, the Ag2Se nanosphere tends to flatten the junction surface by modifying its shape from sphere to hemisphere in order to minimize the conjunct area and thus the interfacial energy. Notably, the crystallographic relationship of the two phases in the heterostructure varies with the lattice parameters of the second phase, in order to reduce the lattice mismatch at the interface. Furthermore, a small lattice mismatch at the interface results in a straight rod-like second phase, while a large lattice mismatch would induce a tortuous product. The reported results may provide a new route for developing novel selenide semiconductor heterostructures which are potentially applicable in optoelectronic, biomedical, photovoltaic and catalytic fields. PMID:24056899

  15. High strength kiloampere Bi2Sr2CaCu2Ox cables for high-field magnet applications

    NASA Astrophysics Data System (ADS)

    Shen, Tengming; Li, Pei; Jiang, Jianyi; Cooley, Lance; Tompkins, John; McRae, Dustin; Walsh, Robert

    2015-06-01

    Multifilamentary Ag-sheathed Bi2Sr2CaCu2Ox (Bi-2212) wire can carry sufficient critical current density Jc for the development of powerful superconducting magnets. However, the range of its applications is limited by the low mechanical strength of the Ag/Bi-2212 strand. A potential solution is to cable Ag/Bi-2212 wire with high-strength materials that are compatible with the Bi-2212 heat treatment in an oxygen atmosphere. Past attempts have not always been successful, because the high-strength materials reacted with Bi-2212 wires, significantly reducing their Jc. We examined the nature of reactions occurring when Ag/Bi-2212 wires are heat-treated in direct contact with several commonly used high-strength alloys and a new Fe-Cr-Al alloy. INCONEL X750 and INCONEL 600 resulted in significant Jc loss, whereas Ni80-Cr caused little or no Jc loss; however, all of them formed chromium oxide that subsequently reacted with silver, creating cracks in the silver sheath. We found that Fe-Cr-Al did not show significant reactions with Ag/Bi-2212 strands. Scanning electron microscopy (SEM) and energy dispersive x-ray (EDS) examinations revealed that the Fe-Cr-Al alloy benefits from the formation of a uniform, crack-free, continuous alumina layer on its surface that does not react with Ag and that helps minimize the Cu loss found with INCONEL X750 and INCONEL 600. We fabricated prototype 6-around-1 cables with six Bi-2212 strands twisted and transposed around an Fe-Cr-Al alloy core coated with TiO2. After standard 1 bar melt processing, the cable retained 100% of the total current-carrying capability of its strands, and, after a 10 bar overpressure processing, the cable reached a total current of 1025 A at 4.2 K and 10 T. Tensile tests showed that Fe-Cr-Al becomes brittle after being cooled to 4.2 K, whereas INCONEL X750 remains ductile and retains a modulus of 183 GPa. We proposed new cable designs that take advantage of the chemical compatibility of Fe-Cr-Al and high strength of

  16. Liquidus Projections of Bi-Se-Ga and Bi-Se-Te Ternary Systems

    NASA Astrophysics Data System (ADS)

    Lin, Po-han; Chen, Sinn-wen; Hwang, Jenn-dong; Chu, Hsu-shen

    2016-06-01

    This study determines the liquidus projections of both Bi-Se-Ga and Bi-Se-Te ternary systems which are constituent ternary systems of promising Bi-Se-Te-Ga thermoelectric materials. Ternary Bi-Se-Ga and Bi-Se-Te alloys are prepared. Their primary solidification phases are experimentally determined, and thermal analysis experiments are carried out. The liquidus projections are determined based on the ternary experimental results and phase diagrams of constituent binary systems. The Bi-Se-Ga system includes seven primary solidification phases, Bi, Ga, GaSe, Ga2Se3, Se, Bi2Se3, and (Bi2)n(Bi2Se3)m. In the Bi-Se-Te system, there are five primary solidification phases, Bi, (Bi2)n(Bi2Te3)m, Bi2(Se,Te)3, (Se,Te), and (Bi2)n(Bi2Se3)m. Both the (Bi2)n(Bi2Te3)m and (Bi2)n(Bi2Se3)m phases are not a single phase, but a collection of series undetermined phases. Large miscibility gaps are observed in the Bi-Se-Ga system. The temperatures of the invariant reactions, Liquid + Bi + GaSe = Ga and Liquid + Ga2Se3 = Bi + GaSe, are at 495 K (222 °C) and 533 K (260 °C), respectively.

  17. Activation of cord T lymphocytes. IV. Analysis of surface expression and functional role of 1F7 (CD26) molecule.

    PubMed

    Gerli, R; Agea, E; Muscat, C; Ercolani, R; Bistoni, O; Tognellini, R; Mariggió, M A; Spinozzi, F; Bertotto, A

    1994-04-15

    A role for CD26 surface antigen (Ag) in both CD3- and CD2-mediated T cell activation has been previously demonstrated. To analyze the functional role of CD26 in the CD3- and CD2-induced activation pathways of cord T cells, which represent the most reliable source of Ag-unprimed T cells, we employed a newly developed anti-CD26 monoclonal antibody, termed anti-1F7, anti-CD3 and anti-CD2 in activating T lymphocytes. The results showed that CD26 Ag is expressed on the surface of almost all resting cord T cells and that its fluorescence intensity is enhanced by activation. The binding of anti-1F7 induced a decrease in CD26 membrane expression, with no detectable effect on the surface expression of other cord T cell-related molecules. Moreover, the modulation of CD26 resulted in an increase in anti-CD3-mediated cord T cell activation through an enhancement in intracellular calcium levels, IL-2 receptor expression, and IL-2 synthesis, whereas it had no effect on cord T cell activation induced by anti-CD2 or anti-CD2 plus exogenous IL-2. The fact that the selective involvement of CD26 in the activation pathway triggered by anti-CD3, but not anti-CD2, could be reversed by prior stimulation of cord T cells with anti-CD3 suggests that this functional feature, which resembles that of mature thymocytes, may be linked to the Ag-unprimed cell phenotype of cord T lymphocytes. PMID:7909498

  18. Antigen targeting reveals splenic CD169+ macrophages as promoters of germinal center B-cell responses.

    PubMed

    Veninga, Henrike; Borg, Ellen G F; Vreeman, Kyle; Taylor, Philip R; Kalay, Hakan; van Kooyk, Yvette; Kraal, Georg; Martinez-Pomares, Luisa; den Haan, Joke M M

    2015-03-01

    Ag delivery to specific APCs is an attractive approach in developing strategies for vaccination. CD169(+) macrophages in the marginal zone of the spleen represent a suitable target for delivery of Ag because of their strategic location, which is optimal for the capture of blood-borne Ag and their close proximity to B cells and T cells in the white pulp. Here we show that Ag targeting to CD169(+) macrophages in mice resulted in strong, isotype-switched, high-affinity Ab production and the preferential induction and long-term persistence of Ag-specific GC B cells and follicular Th cells. In agreement with these observations, CD169(+) macrophages retained intact Ag, induced cognate activation of B cells, and increased expression of costimulatory molecules upon activation. In addition, macrophages were required for the production of cytokines that promote B-cell responses. Our results identify CD169(+) macrophages as promoters of high-affinity humoral immune responses and emphasize the value of CD169 as target for Ag delivery to improve vaccine responses. PMID:25487358

  19. Efficacy evaluation of two synthetic lysine lipidated tripeptides as vaccine adjuvants against HBsAg.

    PubMed

    Sidiq, Tabasum; Khajuria, Anamika; Shafi, Syed; Ismail, Tabasum; Sampath Kumar, Halmathur; Kannappa Srinivas, Vellimedu; Krishna, Ella; Kamal Johri, Rakesh

    2013-04-01

    In the present investigation, adjuvant potential of two novel lipidated tripeptide lysine derivatives (KKSM and KKSMB) was evaluated using various in vitro and animal-derived models of humoral and cell-mediated immune events in response to hepatitis B surface antigen (HBsAg). The results were compared with alum adjuvanted with HBsAg. Both these molecules were found to stimulate anti-HBsAg IgG and neutralizing (IgG1 and IgG2a) antibody titres in mice sera. The two molecules stimulated the proliferation of T-lymphocyte sub-sets (CD4/CD8) as well as the production of soluble mediators of Th1 (IL-2 and IFN-γ) and Th2 response (IL-4) in spleen cell culture supernatant. Furthermore, the two lipidated tripeptides enhanced the CD4, CD8, CD3 and CD19 cell populations as well as CD4/CD8 derived IL-2, IL-4, IFN-γ and TNF-α in whole blood of treated mice. There was found to be the significant enhancement in the release of IL-12, IFN-γ and nitrite content in macrophage supernatant. Moreover, the two lipidated tripeptides enhanced the population of CD80 and CD86 in spleen-derived macrophages and did not show any hemolytic effect on rabbit RBCs. Taken together, these results suggest that both these molecules are the potent enhancers of anti-HBsAg immune response via augmenting Th1/Th2 response in a dose dependent manner. PMID:23474022

  20. 1D ZnO/BiVO4 heterojunction photoanodes for efficient photoelectrochemical water splitting.

    PubMed

    Yan, Lu; Zhao, Wei; Liu, Zhifeng

    2016-07-28

    In this paper, a novel ZnO nanorods (NRs)/BiVO4 heterojunction has been successfully prepared as a photoanode for photoelectrochemical (PEC) water splitting. Firstly, ZnO NRs were synthesized by chemical bath deposition onto indium tin oxide (ITO) coated glass. Then BiVO4 was deposited by successive ionic layer adsorption and reaction (SILAR). The photocurrent density of ZnO NRs and the ZnO NRs/BiVO4 heterojunction photoanode was evaluated under light irradiation. And the value was up to 1.72 mA cm(-2) at 1.2 V vs. Ag/AgCl based on the ZnO NRs/BiVO4 photoanode in the electrolyte solution, which is higher than that of the pure ZnO NRs photoanode at the same potential. It is demonstrated that the presence of BiVO4 has played an important role in expanding the spectral response region and reducing the photogenerated charge recombination rate. This present work provides a simple synthesis route to construct a heterojunction which serves as a photoanode for PEC water splitting. PMID:27328331

  1. 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.

  2. IgE-mediated enhancement of CD4+ T cell responses requires antigen presentation by CD8α− conventional dendritic cells

    PubMed Central

    Ding, Zhoujie; Dahlin, Joakim S.; Xu, Hui; Heyman, Birgitta

    2016-01-01

    IgE, forming an immune complex with small proteins, can enhance the specific antibody and CD4+ T cell responses in vivo. The effects require the presence of CD23 (Fcε-receptor II)+ B cells, which capture IgE-complexed antigens (Ag) in the circulation and transport them to splenic B cell follicles. In addition, also CD11c+ cells, which do not express CD23, are required for IgE-mediated enhancement of T cell responses. This suggests that some type of dendritic cell obtains IgE-Ag complexes from B cells and presents antigenic peptides to T cells. To elucidate the nature of this dendritic cell, mice were immunized with ovalbumin (OVA)-specific IgE and OVA, and different populations of CD11c+ cells, obtained from the spleens four hours after immunization, were tested for their ability to present OVA. CD8α− conventional dendritic cells (cDCs) were much more efficient in inducing specific CD4+ T cell proliferation ex vivo than were CD8α+ cDCs or plasmacytoid dendritic cells. Thus, IgE-Ag complexes administered intravenously are rapidly transported to the spleen by recirculating B cells where they are delivered to CD8α− cDCs which induce proliferation of CD4+ T cells. PMID:27306570

  3. IgE-mediated enhancement of CD4(+) T cell responses requires antigen presentation by CD8α(-) conventional dendritic cells.

    PubMed

    Ding, Zhoujie; Dahlin, Joakim S; Xu, Hui; Heyman, Birgitta

    2016-01-01

    IgE, forming an immune complex with small proteins, can enhance the specific antibody and CD4(+) T cell responses in vivo. The effects require the presence of CD23 (Fcε-receptor II)(+) B cells, which capture IgE-complexed antigens (Ag) in the circulation and transport them to splenic B cell follicles. In addition, also CD11c(+) cells, which do not express CD23, are required for IgE-mediated enhancement of T cell responses. This suggests that some type of dendritic cell obtains IgE-Ag complexes from B cells and presents antigenic peptides to T cells. To elucidate the nature of this dendritic cell, mice were immunized with ovalbumin (OVA)-specific IgE and OVA, and different populations of CD11c(+) cells, obtained from the spleens four hours after immunization, were tested for their ability to present OVA. CD8α(-) conventional dendritic cells (cDCs) were much more efficient in inducing specific CD4(+) T cell proliferation ex vivo than were CD8α(+) cDCs or plasmacytoid dendritic cells. Thus, IgE-Ag complexes administered intravenously are rapidly transported to the spleen by recirculating B cells where they are delivered to CD8α(-) cDCs which induce proliferation of CD4(+) T cells. PMID:27306570

  4. 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.

  5. 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.

  6. 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.

  7. Development and fabrication of a Bi-2223 racetrack coil for generator applications

    SciTech Connect

    Herd, K.G.; Salasoo, L.; Laskaris, E.T.; Ranze, R.A.; King, C.G.; Haldar, P.; Hoehn, J.G.

    1996-12-31

    The development and fabrication of a layer-wound, epoxy-impregnated Bi-2223 high-temperature superconducting (HTS) racetrack coil which generates 40,000 ampere-turns of magnetomotive force (MMF) at 25 K is described. The coil was wound using Ag-sheathed Bi-2223 tape conductor laminated with copper foils for strength enhancement and insulated using a paper-wrap method. After epoxy impregnation, the coil was tested over a range of 16--25 K in a vacuum dewar using a closed-cycle helium refrigeration system. Descriptions of the tape lamination and insulation processing, the coil winding and impregnation, and the experimental test setup are given.

  8. 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).

  9. Colorimetric detection of Bi (III) in water and drug samples using pyridine-2,6-dicarboxylic acid modified silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohammadi, Somayeh; Khayatian, Gholamreza

    2015-09-01

    A new selective, simple, fast and sensitive method is developed for sensing assay of Bi (III) using pyridine-2,6-dicarboxylic acid or dipicolinic acid (DPA) modified silver nanoparticles (DPA-AgNPs). Silver nanoparticles (AgNPs) were synthesized by reducing silver nitrate (AgNO3) with sodium borohydride (NaBH4) in the presence of DPA. Bismuth detection is based on color change of nanoparticle solution from yellow to red that is induced in the presence of Bi (III). Aggregation of DPA-AgNPs has been confirmed with UV-vis absorption spectra and transmission electron microscopy (TEM) images. Under the optimized conditions, a good linear relationship (correlation coefficient r = 0.995) is obtained between the absorbance ratio (A525/A390) and the concentration of Bi (III) in the 0.40-8.00 μM range. This colorimetric probe allows Bi (III) to be rapidly quantified with a 0.01 μM limit of detection. The present method successfully applied to determine bismuth in real water and drug samples. Recoveries of water samples were in the range of 91.2-99.6%.

  10. Colorimetric detection of Bi (III) in water and drug samples using pyridine-2,6-dicarboxylic acid modified silver nanoparticles.

    PubMed

    Mohammadi, Somayeh; Khayatian, Gholamreza

    2015-09-01

    A new selective, simple, fast and sensitive method is developed for sensing assay of Bi (III) using pyridine-2,6-dicarboxylic acid or dipicolinic acid (DPA) modified silver nanoparticles (DPA-AgNPs). Silver nanoparticles (AgNPs) were synthesized by reducing silver nitrate (AgNO3) with sodium borohydride (NaBH4) in the presence of DPA. Bismuth detection is based on color change of nanoparticle solution from yellow to red that is induced in the presence of Bi (III). Aggregation of DPA-AgNPs has been confirmed with UV-vis absorption spectra and transmission electron microscopy (TEM) images. Under the optimized conditions, a good linear relationship (correlation coefficient r=0.995) is obtained between the absorbance ratio (A525/A390) and the concentration of Bi (III) in the 0.40-8.00 μM range. This colorimetric probe allows Bi (III) to be rapidly quantified with a 0.01 μM limit of detection. The present method successfully applied to determine bismuth in real water and drug samples. Recoveries of water samples were in the range of 91.2-99.6%. PMID:25919329

  11. Improving the field-effect performance of Bi2S3 single nanowires by an asymmetric device fabrication.

    PubMed

    Lu, Fangyuan; Li, Renxiong; Li, Yan; Huo, Nengjie; Yang, Juehan; Li, Yongtao; Li, Bo; Yang, Shengxue; Wei, Zhongming; Li, Jingbo

    2015-01-12

    High-quality Bi2 S3 nanowires are synthesized by chemical vapor deposition and their intrinsic photoresponsive and field-effect characteristics are explored in detail. Among the studied Au-Au, Ag-Ag, and Au-Ag electrode pairs, the device with stepwise band alignment of asymmetric Au-Ag electrodes has the highest mobility. Furthermore, it is shown that light can cause a sevenfold decrease of the on/off ratio. This can be explained by the photoexcited charge carriers that are more beneficial to the increase of Ioff than Ion . The photoresponsive properties of the asymmetric Au-Ag electrode devices were also explored, and the results show a photoconductive gain of seven with a rise time of 2.9 s and a decay time of 1.6 s. PMID:25294685

  12. Shortened Intervals during Heterologous Boosting Preserve Memory CD8 T Cell Function but Compromise Longevity.

    PubMed

    Thompson, Emily A; Beura, Lalit K; Nelson, Christine E; Anderson, Kristin G; Vezys, Vaiva

    2016-04-01

    Developing vaccine strategies to generate high numbers of Ag-specific CD8 T cells may be necessary for protection against recalcitrant pathogens. Heterologous prime-boost-boost immunization has been shown to result in large quantities of functional memory CD8 T cells with protective capacities and long-term stability. Completing the serial immunization steps for heterologous prime-boost-boost can be lengthy, leaving the host vulnerable for an extensive period of time during the vaccination process. We show in this study that shortening the intervals between boosting events to 2 wk results in high numbers of functional and protective Ag-specific CD8 T cells. This protection is comparable to that achieved with long-term boosting intervals. Short-boosted Ag-specific CD8 T cells display a canonical memory T cell signature associated with long-lived memory and have identical proliferative potential to long-boosted T cells Both populations robustly respond to antigenic re-exposure. Despite this, short-boosted Ag-specific CD8 T cells continue to contract gradually over time, which correlates to metabolic differences between short- and long-boosted CD8 T cells at early memory time points. Our studies indicate that shortening the interval between boosts can yield abundant, functional Ag-specific CD8 T cells that are poised for immediate protection; however, this is at the expense of forming stable long-term memory. PMID:26903479

  13. 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.

  14. Bi-stem gripping apparatus

    NASA Technical Reports Server (NTRS)

    Sanders, Fred G. (Inventor)

    1988-01-01

    This invention relates to devices which grip cylindrical structures and more particularly to a device which has three arcuate gripping members having frictional surfaces for gripping and compressing a bi-stem. The bi-stem gripping apparatus is constructed having a pair of side gripping members, and an intermediate gripping member disposed between them. Sheets of a gum stock silicone rubber with frictional gripping surfaces are bonded to the inner region of the gripping members and provide frictional engagement between the bi-stem and the apparatus. A latch secures the gripping apparatus to a bi-stem, and removable handles are attached, allowing an astronaut to pull the bi-stem from its cassette. A tethering ring on the outside of the gripping apparatus provides a convenient point to which a lanyard may be attached.

  15. Nonvolatile conductive filaments resistive switching behaviors in Ag/GaO x /Nb:SrTiO3/Ag structure

    NASA Astrophysics Data System (ADS)

    Li, P. G.; Zhi, Y. S.; Wang, P. C.; Sun, Z. B.; Li, L. H.; An, Y. H.; Guo, D. Y.; Tang, W. H.; Xiao, J. H.

    2016-07-01

    Ag/GaO x /NSTO/Ag structures were fabricated, and the electrical properties measurement results show that the device behaviors a unipolar resistance switching characteristic with bi-stable resistance ratio of three orders. In the positive voltage region, the dominant conducting mechanism of high resistance state obeys Poole-Frenkel emission rules, while in the negative region, that obeys space-charge-limited current mechanism. Both the I- V curves of ON and OFF states and temperature-dependent variation resistances indicate that the unipolar resistance switching behavior can be explained by the formation/rupture of conductive filaments, which composed of oxygen vacancies. The stable switching results demonstrated that the structure can be applied in resistance random access memory devices.

  16. Retrogenic ICOS Expression Increases Differentiation of KLRG-1hiCD127loCD8+ T Cells during Listeria Infection and Diminishes Recall Responses.

    PubMed

    Liu, Danya; Burd, Eileen M; Coopersmith, Craig M; Ford, Mandy L

    2016-02-01

    Following T cell encounter with Ag, multiple signals are integrated to collectively induce distinct differentiation programs within Ag-specific CD8(+) T cell populations. Several factors contribute to these cell fate decisions, including the amount and duration of Ag, exposure to inflammatory cytokines, and degree of ligation of cosignaling molecules. The ICOS is not expressed on resting T cells but is rapidly upregulated upon encounter with Ag. However, the impact of ICOS signaling on programmed differentiation is not well understood. In this study, we therefore sought to determine the role of ICOS signaling on CD8(+) T cell programmed differentiation. Through the creation of novel ICOS retrogenic Ag-specific TCR-transgenic CD8(+) T cells, we interrogated the phenotype, functionality, and recall potential of CD8(+) T cells that receive early and sustained ICOS signaling during Ag exposure. Our results reveal that these ICOS signals critically impacted cell fate decisions of Ag-specific CD8(+) T cells, resulting in increased frequencies of KLRG-1(hi)CD127(lo) cells, altered BLIMP-1, T-bet, and eomesodermin expression, and increased cytolytic capacity as compared with empty vector controls. Interestingly, however, ICOS retrogenic CD8(+) T cells also preferentially homed to nonlymphoid organs and exhibited reduced multicytokine functionality and reduced ability to mount secondary recall responses upon challenge in vivo. In sum, our results suggest that an altered differentiation program is induced following early and sustained ICOS expression, resulting in the generation of more cytolyticly potent, terminally differentiated effectors that possess limited capacity for recall response. PMID:26729800

  17. Synthesis, Characterization and Photocatalytic Activity of New Photocatalyst ZnBiSbO4 under Visible Light Irradiation

    PubMed Central

    Luan, Jingfei; Chen, Mengjing; Hu, Wenhua

    2014-01-01

    In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. PMID:24879521

  18. The use of a directional solidification technique to investigate the interrelationship of thermal parameters, microstructure and microhardness of Bi–Ag solder alloys

    SciTech Connect

    Spinelli, José Eduardo; Silva, Bismarck Luiz; Cheung, Noé; Garcia, Amauri

    2014-10-15

    Bi–Ag alloys have been stressed as possible alternatives to replace Pb-based solder alloys. Although acceptable melting temperatures and suitable mechanical properties may characterize such alloys, as referenced in literature, there is a lack of comprehension regarding their microstructures (morphologies and sizes of the phases) considering a composition range from 1.5 to 4.0 wt.%Ag. In order to better comprehend such aspects and their correlations with solidification thermal parameters (growth rate, v and cooling rate, T-dot), directional solidification experiments were carried out under transient heat flow conditions. The effects of Ag content on both cooling rate and growth rate during solidification are examined. Microstructure parameters such as eutectic/dendritic spacing, interphase spacing and diameter of the Ag-rich phase were determined by optical microscopy and scanning electron microscopy. The competition between eutectic cells and dendrites in the range from 1.5 to 4.0 wt.%Ag is explained by the coupled zone concept. Microhardness was determined for different microstructures and alloy Ag contents with a view to permitting correlations with microstructure parameters to be established. Hardness is shown to be directly affected by both solute macrosegregation and morphologies of the phases forming the Bi–Ag alloys, with higher hardness being associated with the cellular morphology of the Bi-2.5 and 4.0 wt.%Ag alloys. - Highlights: • Asymmetric zone of coupled growth for Bi–Ag is demonstrated. • Faceted Bi-rich dendrites have been characterized for Bi–1.5 wt.%Ag alloy. • Eutectic cells were shown for the Bi-2.5 and 4.0 wt.%Ag solder alloys. • Interphase spacing relations with G × v are able to represent the experimental scatters. • Hall-Petch type equations are proposed relating microstructural spacings to hardness.

  19. A new Schiff base based on vanillin and naphthalimide as a fluorescent probe for Ag+ in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhou, Yanmei; Zhou, Hua; Ma, Tongsen; Zhang, Junli; Niu, Jingyang

    2012-03-01

    A new Schiff base based on vanillin and naphthalimide was designed and synthesized as fluorescent probe. The probe showed high selectivity for Ag+ over other metal ions such as Pb2+, Na+, K+, Cd2+, Ba2+, Cr3+, Zn2+, Cu2+, Ni2+, Ca2+, Al3+ and Mg2+ in aqueous solution. A new fluorescence emission was observed at 682 nm in the presence of Ag+ ion. The fluorescence intensity quenched with increasing the concentration of Ag+ at 682 nm. The method of job's plot confirmed the 1:2 complex between Ag+ and probe, and the mechanism was proposed.

  20. Activation of cord T lymphocytes. III. Role of LFA-1/ICAM-1 and CD2/LFA-3 adhesion molecules in CD3-induced proliferative response.

    PubMed

    Gerli, R; Agea, E; Muscat, C; Tognellini, R; Fiorucci, G; Spinozzi, F; Cernetti, C; Bertotto, A

    1993-04-15

    As cord T cells, a model of antigen (Ag)-unprimed cell, display a functional defect when stimulated through the CD3 molecule, the role of lymphocyte function-associated antigen 1(LFA-1)/intercellular adhesion molecule 1 (ICAM-1) and CD2/lymphocyte function-associated antigen 3 (LFA-3) receptor-ligand pairs in cord CD3-triggered T-cell activation was analyzed using specific monoclonal antibodies (mAb) against each adhesion molecule. The addition of anti-CD11a, anti-CD18, or anti-CD2 to both adult and cord peripheral blood mononuclear cells (PBMC) cultures led to a decrease in CD3-induced proliferation. In contrast, CD3-stimulated cord, but not adult, PBMC proliferation was markedly enhanced when anti-CD54 or anti-CD58 were added. Despite the fact that ICAM-1 and LFA-3 molecules were virtually absent on cord resting T cells, mAb against these two molecules boosted both mitogenesis of and interleukin (IL)-2 production by purified cord T cells stimulated with plastic immobilized anti-CD3. Cord T-cell supernatant levels of interferon-gamma (IFN-gamma) were undetectable with CD3 stimulation, slightly raised with CD58/CD3 costimulation, but normal when T cells were preincubated with IL-2 for 24 hr before being costimulated with anti-CD3/CD58. Evidence that IL-2 and IFN-gamma play a pivotal role in fully activating cord T cells came from the demonstration that IL-2 and IFN-gamma are able to bypass the CD3-proliferative defect through differential up-regulation of the adhesion molecules. It would, therefore, seem that ICAM-1 and LFA-3 molecules are crucially implicated in the CD3-activation pathway of Ag-unprimed T cells. PMID:7684326

  1. Molecular Beam Epitaxy Growth of GaBi, InBi and InGaBi

    NASA Astrophysics Data System (ADS)

    Keen, B.; Makin, R.; Stampe, P. A.; Kennedy, R. J.; Piper, L. F. J.; McCombe, B.; McConville, C. F.; Durbin, S. M.

    2014-03-01

    Recent interest in bismuth alloys of III-V semiconductors for infrared and far-infrared device applications, specifically GaAsBi and InAsBi, has indicated that further study of the III-Bi family of binary compounds would be of great help in improving the quality of these material systems. While immiscibility issues have so far frustrated the growth of GaBi and AlBi, InBi is less problematic, and we have grown it by molecular beam epitaxy on (001) GaAs substrates. However, regions of varying composition exist across the substrate due to poor wetting of the surface. In an effort to improve film quality we have continued to refine the growth parameters by adjusting substrate temperature, beam flux ratio, and deposition rate. Characterization of these films has been performed by x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Additionally, we have explored growth of GaBi and In1-xGaxBi at low Ga mole fractions, and modeled this using molecular dynamics simulations. This work is supported by the Research Foundation of the State University of New York Collaborations Fund.

  2. Facile fabrication of an efficient BiVO4 thin film electrode for water splitting under visible light irradiation.

    PubMed

    Jia, Qingxin; Iwashina, Katsuya; Kudo, Akihiko

    2012-07-17

    An efficient BiVO(4) thin film electrode for overall water splitting was prepared by dipping an F-doped SnO(2) (FTO) substrate electrode in an aqueous nitric acid solution of Bi(NO(3))(3) and NH(4)VO(3), and subsequently calcining it. X-ray diffraction of the BiVO(4) thin film revealed that a photocatalytically active phase of scheelite-monoclinic BiVO(4) was obtained. Scanning electron microscopy images showed that the surface of an FTO substrate was uniformly coated with the BiVO(4) film with 300-400 nm of the thickness. The BiVO(4) thin film electrode gave an excellent anodic photocurrent with 73% of an IPCE at 420 nm at 1.0 V vs. Ag/AgCl. Modification with CoO on the BiVO(4) electrode improved the photoelectrochemical property. A photoelectrochemical cell consisting of the BiVO(4) thin film electrode with and without CoO, and a Pt counter electrode was constructed for water splitting under visible light irradiation and simulated sunlight irradiation. Photocurrent due to water splitting to form H(2) and O(2) was confirmed with applying an external bias smaller than 1.23 V that is a theoretical voltage for electrolysis of water. Water splitting without applying external bias under visible light irradiation was demonstrated using a SrTiO(3)Rh photocathode and the BiVO(4) photoanode. PMID:22699499

  3. Facile fabrication of an efficient BiVO4 thin film electrode for water splitting under visible light irradiation

    PubMed Central

    Jia, Qingxin; Iwashina, Katsuya; Kudo, Akihiko

    2012-01-01

    An efficient BiVO4 thin film electrode for overall water splitting was prepared by dipping an F-doped SnO2 (FTO) substrate electrode in an aqueous nitric acid solution of Bi(NO3)3 and NH4VO3, and subsequently calcining it. X-ray diffraction of the BiVO4 thin film revealed that a photocatalytically active phase of scheelite-monoclinic BiVO4 was obtained. Scanning electron microscopy images showed that the surface of an FTO substrate was uniformly coated with the BiVO4 film with 300–400 nm of the thickness. The BiVO4 thin film electrode gave an excellent anodic photocurrent with 73% of an IPCE at 420 nm at 1.0 V vs. Ag/AgCl. Modification with CoO on the BiVO4 electrode improved the photoelectrochemical property. A photoelectrochemical cell consisting of the BiVO4 thin film electrode with and without CoO, and a Pt counter electrode was constructed for water splitting under visible light irradiation and simulated sunlight irradiation. Photocurrent due to water splitting to form H2 and O2 was confirmed with applying an external bias smaller than 1.23 V that is a theoretical voltage for electrolysis of water. Water splitting without applying external bias under visible light irradiation was demonstrated using a SrTiO3∶Rh photocathode and the BiVO4 photoanode. PMID:22699499

  4. Fabrication of Cu-Ag core-shell bimetallic superfine powders by eco-friendly reagents and structures characterization

    SciTech Connect

    Zhao Jun; Zhang Dongming; Zhao Jie

    2011-09-15

    Superfine bimetallic Cu-Ag core-shell powders were synthesized by reduction of copper sulfate pentahydrate and silver nitrate with eco-friendly ascorbic acid as a reducing agent and cyclodextrins as a protective agent in an aqueous system. The influence of Ag/Cu ratio on coatings was investigated. Ag was homogeneously distributed on the surface of Cu particles at a mole ratio of Ag/Cu=1. FE-SEM showed an uniformity of Ag coatings on Cu particles. Antioxidation of Cu particles was improved by increasing Ag/Cu ratio. TEM-EDX and UV-vis spectra also revealed that Cu cores were covered by Ag nanoshells on the whole. The surface composition analysis by XPS indicated that only small parts of Cu atoms in the surface were oxidized. It was noted that the hindrance of cyclodextrins chemisorbed on particles plays an important role in forming high quality and good dispersity Cu-Ag (Cu-Ag) core-shell powders. - Graphical abstract: Mechanism of fabricating Cu-Ag particles with good dispersibility using {beta}-CDs as a protective agent was studied because of its special structure. Highlights: > Green supramolecular {beta}-CD used as a protective agent and ascorbic acid(Vc) as a reducing agent to fabricate Cu-Ag powders. > Particles are monodisperse and the diameter is close to nanoscale(100-150 nm). > Resistance of Cu particles to oxidation was higher. > Formation mechanism explained.

  5. Antigen targeting reveals splenic CD169+ macrophages as promoters of germinal center B‐cell responses

    PubMed Central

    Veninga, Henrike; Borg, Ellen G. F.; Vreeman, Kyle; Taylor, Philip R.; Kalay, Hakan; van Kooyk, Yvette; Kraal, Georg; Martinez‐Pomares, Luisa

    2015-01-01

    Ag delivery to specific APCs is an attractive approach in developing strategies for vaccination. CD169+ macrophages in the marginal zone of the spleen represent a suitable target for delivery of Ag because of their strategic location, which is optimal for the capture of blood‐borne Ag and their close proximity to B cells and T cells in the white pulp. Here we show that Ag targeting to CD169+ macrophages in mice resulted in strong, isotype‐switched, high‐affinity Ab production and the preferential induction and long‐term persistence of Ag‐specific GC B cells and follicular Th cells. In agreement with these observations, CD169+ macrophages retained intact Ag, induced cognate activation of B cells, and increased expression of costimulatory molecules upon activation. In addition, macrophages were required for the production of cytokines that promote B‐cell responses. Our results identify CD169+ macrophages as promoters of high‐affinity humoral immune responses and emphasize the value of CD169 as target for Ag delivery to improve vaccine responses. PMID:25487358

  6. Influence of dopant concentration on the electrical properties of the CdSe-PMMA nanocomposite

    NASA Astrophysics Data System (ADS)

    Kaur, Ramneek; Tripathi, S. K.

    2016-05-01

    This paper reports the synthesis and electrical characterization of CdSe-PMMA nanocomposite. CdSe-PMMA nanocomposite has been prepared by ex-situ technique through chemical route. The influence of three different Ag doping concentrations on the electrical properties has been studied in the temperature range ˜ 303-353 K. Transmission electron micrograph reveals the spherical morphology of the CdSe nanoparticles and their proper dispersion in the PMMA matrix. The electrical conduction of the polymer nanocomposites is through thermally activated process with single activation energy. With Ag doping, initially the activation energy increases upto 0.2 % Ag doping concentration but with further increase in Ag concentration, it decreases. This behavior has been discussed on the basis of randomly oriented grain boundaries and defect states. Thus, the results indicate that the transport properties of the polymer nanocomposites can be tailored by controlled doping concentration.

  7. ABiO2X (A = Cd, Ca, Sr, Ba, Pb; X = halogen) Sillen X1 Series: Polymorphism Versus Optical Properties.

    PubMed

    Olchowka, Jacob; Kabbour, Houria; Colmont, Marie; Adlung, Matthias; Wickleder, Claudia; Mentré, Olivier

    2016-08-01

    The Sillen X1 series of Bi(3+)A(2+)O2X (A = Cd, Ca, Sr, Ba, Pb; X = Cl, Br, I) compounds is composed of three main crystallographic types, namely, the tetragonal form (space group (S.G.) I4/mmm), the orthorhombic form (S.G. Cmcm), and the monoclinic form (S.G. P21/m). Because of Bi(3+)/A(2+) disorder the Bi(3+) based photoluminescence (PL) of the tetragonal polytypes is quenched at room temperature (RT). In the two other ordered forms, the Bi-O-Bi connectivity is different but limited, such that bluish/greenish emission occurs at RT in the monoclinic CdBiO2Cl and CaBiO2Cl and orthorhombic SrBiO2Cl and BaBiO2Cl phases. The crystal structure of BaBiO2Br was refined in the orthorhombic Cmcm space group and also shows RT emission. Focusing on the RT luminescent activity as a key parameter, the PL active compounds were investigated by means of density functional theory calculations and UV-visible reflectance spectroscopy. The influence of A and X ions on the excitation energy is discussed by analyzing the A-O-Bi and Bi-X bonding schemes and gives some insights for rational tuning of both the excitation and emission energies. PMID:27414069

  8. 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.

  9. Bone marrow mesenchymal stromal cells with CD47 high expression via the signal transducer and activators of transcription signaling pathway preventing myocardial fibrosis

    PubMed Central

    Deng, Wei; Chen, Qing-Wei; Li, Xing-Sheng; Yuan, Zhong-Ming; Li, Gui-Qiong; Ke, Da-Zhi; Wang, Li; Wu, Zhi-Qing; Luo, Shi-Lan

    2015-01-01

    This study was initiated to investigate the efficacy of myocardial fibrosis intervention via signal transducer and activators of transcription (STAT) signaling using bone marrow (BM) mesenchymal stromal cells (MSC) in which being over-expressed with the aid of bispecific antibody (BiAb) and ultrasound-mediated microbubbles (MB). BiAb was prepared and combined with isolated MSC with CD47 overexpression from male mice and trans-fused into female mice with isoproterenol-induced myocardial fibrosis via the tail vein, followed by MB. This study included five groups. Five weeks after treatment, expression levels of the sex-determining region of Y-chromosome (SRY), matrix metalloproteinases (MMP)-9, tissue inhibitor of metalloproteinase (TIMP)-1 and vascular endothelial growth factor (VEGF) in myocardium were detected by fluorescent quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of signal transducer and activators of transcription (STAT) 1 and STAT 3 was detected by Western blot. Results: The highest homing number of MSC was in the CD47 + MSC + BiAb + MB group, second highest in the CD47 + MSC + BiAb group, and lowest in MSC alone. Compared with the Control group, CD47 + MSC + BiAb + MB, CD47 + MSC + BiAb, CD47 + MSC and MSC groups had decreased levels of MMP-9, TIMP-1, STAT 1 and collagen deposition, and increased levels of STAT 3. Up regulated STAT 3 and down regulated TIMP-1 were significantly different in CD47 + MSC + BiAb + MB compared with CD47 + MSC or CD47 + MSC + BiAb. Conclusion: CD47 can enhance the homing rate and repairing efficacy of MSC. MSC can improve MMP-TIMP expression in injured myocardium and interfere with myocardial fibrosis after homing, a mechanism that may be related to the STAT-mediated signaling pathway. PMID:26617765

  10. The microstructure of MnBi/Bi eutectic alloys

    NASA Technical Reports Server (NTRS)

    Ravishankar, P. S.; Wilcox, W. R.; Larson, D. J.

    1980-01-01

    Directionally solidified eutectic alloys of the system MnBi/Bi have been investigated with reference to the dependence of the fiber spacing on the growth rate and the interfacial temperature gradient. It is found that the fiber spacing varies as the inverse square root of the growth rate and does not depend on the temperature gradient in contrast to the claims that all faceted/non-faceted eutectics should show a temperature gradient influence.

  11. Immediate Dysfunction of Vaccine-Elicited CD8+ T Cells Primed in the Absence of CD4+ T Cells.

    PubMed

    Provine, Nicholas M; Larocca, Rafael A; Aid, Malika; Penaloza-MacMaster, Pablo; Badamchi-Zadeh, Alexander; Borducchi, Erica N; Yates, Kathleen B; Abbink, Peter; Kirilova, Marinela; Ng'ang'a, David; Bramson, Jonathan; Haining, W Nicholas; Barouch, Dan H

    2016-09-01

    CD4(+) T cell help is critical for optimal CD8(+) T cell memory differentiation and maintenance in many experimental systems. In addition, many reports have identified reduced primary CD8(+) T cell responses in the absence of CD4(+) T cell help, which often coincides with reduced Ag or pathogen clearance. In this study, we demonstrate that absence of CD4(+) T cells at the time of adenovirus vector immunization of mice led to immediate impairments in early CD8(+) T cell functionality and differentiation. Unhelped CD8(+) T cells exhibited a reduced effector phenotype, decreased ex vivo cytotoxicity, and decreased capacity to produce cytokines. This dysfunctional state was imprinted within 3 d of immunization. Unhelped CD8(+) T cells expressed elevated levels of inhibitory receptors and exhibited transcriptomic exhaustion and anergy profiles by gene set enrichment analysis. Dysfunctional, impaired effector differentiation also occurred following immunization of CD4(+) T cell-deficient mice with a poxvirus vector. This study demonstrates that following priming with viral vectors, CD4(+) T cell help is required to promote both the expansion and acquisition of effector functions by CD8(+) T cells, which is accomplished by preventing immediate dysfunction. PMID:27448585

  12. Immediate Dysfunction of Vaccine-Elicited CD8+ T Cells Primed in the Absence of CD4+ T Cells

    PubMed Central

    Provine, Nicholas M.; Larocca, Rafael A.; Aid, Malika; Penaloza-MacMaster, Pablo; Badamchi-Zadeh, Alexander; Borducchi, Erica N.; Yates, Kathleen B.; Abbink, Peter; Kirilova, Marinela; Ng’ang’a, David; Bramson, Jonathan; Haining, W. Nicholas

    2016-01-01

    CD4+ T cell help is critical for optimal CD8+ T cell memory differentiation and maintenance in many experimental systems. In addition, many reports have identified reduced primary CD8+ T cell responses in the absence of CD4+ T cell help, which often coincides with reduced Ag or pathogen clearance. In this study, we demonstrate that absence of CD4+ T cells at the time of adenovirus vector immunization of mice led to immediate impairments in early CD8+ T cell functionality and differentiation. Unhelped CD8+ T cells exhibited a reduced effector phenotype, decreased ex vivo cytotoxicity, and decreased capacity to produce cytokines. This dysfunctional state was imprinted within 3 d of immunization. Unhelped CD8+ T cells expressed elevated levels of inhibitory receptors and exhibited transcriptomic exhaustion and anergy profiles by gene set enrichment analysis. Dysfunctional, impaired effector differentiation also occurred following immunization of CD4+ T cell–deficient mice with a poxvirus vector. This study demonstrates that following priming with viral vectors, CD4+ T cell help is required to promote both the expansion and acquisition of effector functions by CD8+ T cells, which is accomplished by preventing immediate dysfunction. PMID:27448585

  13. LiBi3S5-A lithium bismuth sulfide with strong cation disorder

    NASA Astrophysics Data System (ADS)

    Nakhal, Suliman; Wiedemann, Dennis; Stanje, Bernhard; Dolotko, Oleksandr; Wilkening, Martin; Lerch, Martin

    2016-06-01

    Among chalcogenide semiconductors for thermoelectric applications, alkali-metal bismuth compounds occur in many complex compositions favorable for high performance. Although LiBi3S5 had been announced in 1977, the potential 1D lithium-ion conductor has hitherto eluded selective synthesis and structure determination. In this study, we present a solid-state route to phase-pure LiBi3S5 powder starting from LiBiS2 and Bi2S3. Neutron diffractograms and lithium NMR spectra reveal its crystal structure to be a cation-disordered variety of the AgBi3S5 type (synthetic pavonite; monoclinic, C2/m). Topological analyses and lithium NMR relaxometry suggest that correlated lithium-ion diffusion with activation energies up to 0.66(2) eV occurs along the channels in b direction including tetrahedral voids. Because of cation disorder, immobile bismuth(III) ions clog these pathways, making LiBi3S5 a moderate to poor ionic conductor. The synthesis route reported is nonetheless promising for new lithium bismuth sulfides with, possibly ordered, structure types of the pavonite homologous series.

  14. 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.

  15. 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

  16. β-Cyclodextrin coated SiO₂@Au@Ag core-shell nanoparticles for SERS detection of PCBs.

    PubMed

    Lu, Yilin; Yao, Guohua; Sun, Kexi; Huang, Qing

    2015-09-01

    A new type of surface-enhanced Raman scattering (SERS) substrate consisting of β-cyclodextrin (β-CD) coated SiO2@Au@Ag nanoparticles (SiO2@Au@Ag@CD NPs) has been achieved. Our protocol was a simplified approach as the fabrication and modification of the silver shell were realized in a single-step reaction by taking advantage of β-CD as both the reducing and stabilizing agents. The as-synthesized SiO2@Au@Ag@CD NPs were uniform in size and demonstrated high SERS activity and reproducibility. The substrates consisting of the SiO2@Au@Ag@CD NPs were employed for SERS detection of polychlorinated biphenyls (PCBs) including PCB-3, PCB-29 and PCB-77. The SERS detection sensitivity was significantly improved due to enrichment of more PCB molecules captured by β-CD on the substrate surface, as confirmed by the appearance of the new Raman bands which are attributed to the complexes between β-CD and PCBs according to the theoretical simulation. Therefore, this work presents a novel approach to the fabrication of effective SERS substrates that can be employed for rapid determination of trace amounts of PCBs in the environment with high detection sensitivity and recognition selectivity. PMID:25478906

  17. Microstructural behavior of iron and bismuth added Sn-1Ag-Cu solder under elevated temperature aging

    NASA Astrophysics Data System (ADS)

    Ali, Bakhtiar; Sabri, Mohd Faizul Mohd; Jauhari, Iswadi

    2016-07-01

    An extensive study was done to investigate the microstructural behavior of iron (Fe) and bismuth (Bi) added Sn-1Ag-0.5Cu (SAC105) under severe thermal aging conditions. The isothermal aging was done at 200 °C for 100 h, 200 h, and 300 h. Optical microscopy with cross-polarized light revealed that the grain size significantly reduces with Fe/Bi addition to the base alloy SAC105 and remains literally the same after thermal aging. The micrographs of field emission scanning electron microscopy (FESEM) with backscattered electron detector and their further analysis via imageJ software indicated that Fe/Bi added SAC105 showed a significant reduction in the IMCs size (Ag3Sn and Cu6Sn5), especially the Cu6Sn5 IMCs, as well as β-Sn matrix and a refinement in the microstructure, which is due to the presence of Bi in the alloys. Moreover, their microstructure remains much more stable under severe thermal aging conditions, which is because of the presence of both Fe and Bi in the alloy. The microstructural behavior suggests that Fe/Bi modified SAC105 would have much improved reliability under severe thermal environments. These modified alloys also have relatively low melting temperature and low cost.

  18. Cutting edge: Failure of antigen-specific CD4+ T cell recruitment to the kidney during systemic candidiasis.

    PubMed

    Drummond, Rebecca A; Wallace, Carol; Reid, Delyth M; Way, Sing Sing; Kaplan, Daniel H; Brown, Gordon D

    2014-12-01

    Candida albicans is the leading cause of systemic candidiasis, a fungal disease associated with high mortality and poor treatment options. The kidney is the target organ during infection and whose control is largely dependent on innate immunity, because lymphocytes appear redundant for protection. In this article, we show that this apparent redundancy stems from a failure of Ag-specific CD4(+) T cells to migrate into infected kidneys. In contrast, Ag-specific CD8(+) T cells are recruited normally. Using Ag-loaded immunoliposomes to artificially reverse this defective migration, we show that recruited Ag-specific CD4(+) T cells polarize toward a Th17 phenotype in the kidney and are protective during fungal infection. Therefore, our data explain the redundancy of CD4(+) T cells for defense against systemic infection with C. albicans and have important implications for our understanding of antifungal immunity and the control of renal infections. PMID:25344471

  19. Investigation of current transport normal and parallel to the tape plane in BSCCO/Ag tapes

    SciTech Connect

    Maley, M.P.; Cho, J.H.; Willis, J.O.; Bulaevskii, L.N.

    1995-07-01

    We have performed transport, resistivity and critical current measurements on Bi-2223/Ag and Bi-2212/Ag tapes with current directions both parallel and perpendicular to the tape plane in magnetic fields up to 7 T and 50

  20. NSOM/QD-Based Direct Visualization of CD3-Induced and CD28-Enhanced Nanospatial Coclustering of TCR and Coreceptor in Nanodomains in T Cell Activation

    PubMed Central

    Lu, Xiaoxu; Wang, Richard C.; Gong, Guangming; Yan, Lin; Huang, Dan; Chen, Zheng W.

    2009-01-01

    Direct molecular imaging of nano-spatial relationship between T cell receptor (TCR)/CD3 and CD4 or CD8 co-receptor before and after activation of a primary T cell has not been reported. We have recently innovated application of near-field scanning optical microscopy (NSOM) and immune-labeling quantum dots (QD) to image Ag-specific TCR response during in vivo clonal expansion, and now up-graded the NSOM/QD-based nanotechnology through dipole-polarization and dual-color imaging. Using this imaging system scanning cell-membrane molecules at a best-optical lateral resolution, we demonstrated that CD3, CD4 or CD8 molecules were distinctly distributed as single QD-bound molecules or nano-clusters equivalent to 2–4 QD fluorescence-intensity/size on cell-membrane of un-stimulated primary T cells, and ∼6–10% of CD3 were co-clustering with CD4 or CD8 as 70–110 nm nano-clusters without forming nano-domains. The ligation of TCR/CD3 on CD4 or CD8 T cells led to CD3 nanoscale co-clustering or interaction with CD4 or CD8 co-receptors forming 200–500 nm nano-domains or >500 nm micro-domains. Such nano-spatial co-clustering of CD3 and CD4 or CD3 and CD8 appeared to be an intrinsic event of TCR/CD3 ligation, not purely limited to MHC engagement, and be driven by Lck phosphorylation. Importantly, CD28 co-stimulation remarkably enhanced TCR/CD3 nanoscale co-clustering or interaction with CD4 co-receptor within nano- or micro-domains on the membrane. In contrast, CD28 co-stimulation did not enhance CD8 clustering or CD3–CD8 co-clustering in nano-domains although it increased molecular number and density of CD3 clustering in the enlarged nano-domains. These nanoscale findings provide new insights into TCR/CD3 interaction with CD4 or CD8 co-receptor in T-cell activation. PMID:19536289

  1. NSOM/QD-based direct visualization of CD3-induced and CD28-enhanced nanospatial coclustering of TCR and coreceptor in nanodomains in T cell activation.

    PubMed

    Zhong, Liyun; Zeng, Gucheng; Lu, Xiaoxu; Wang, Richard C; Gong, Guangming; Yan, Lin; Huang, Dan; Chen, Zheng W

    2009-01-01

    Direct molecular imaging of nano-spatial relationship between T cell receptor (TCR)/CD3 and CD4 or CD8 co-receptor before and after activation of a primary T cell has not been reported. We have recently innovated application of near-field scanning optical microscopy (NSOM) and immune-labeling quantum dots (QD) to image Ag-specific TCR response during in vivo clonal expansion, and now up-graded the NSOM/QD-based nanotechnology through dipole-polarization and dual-color imaging. Using this imaging system scanning cell-membrane molecules at a best-optical lateral resolution, we demonstrated that CD3, CD4 or CD8 molecules were distinctly distributed as single QD-bound molecules or nano-clusters equivalent to 2-4 QD fluorescence-intensity/size on cell-membrane of un-stimulated primary T cells, and approximately 6-10% of CD3 were co-clustering with CD4 or CD8 as 70-110 nm nano-clusters without forming nano-domains. The ligation of TCR/CD3 on CD4 or CD8 T cells led to CD3 nanoscale co-clustering or interaction with CD4 or CD8 co-receptors forming 200-500 nm nano-domains or >500 nm micro-domains. Such nano-spatial co-clustering of CD3 and CD4 or CD3 and CD8 appeared to be an intrinsic event of TCR/CD3 ligation, not purely limited to MHC engagement, and be driven by Lck phosphorylation. Importantly, CD28 co-stimulation remarkably enhanced TCR/CD3 nanoscale co-clustering or interaction with CD4 co-receptor within nano- or micro-domains on the membrane. In contrast, CD28 co-stimulation did not enhance CD8 clustering or CD3-CD8 co-clustering in nano-domains although it increased molecular number and density of CD3 clustering in the enlarged nano-domains. These nanoscale findings provide new insights into TCR/CD3 interaction with CD4 or CD8 co-receptor in T-cell activation. PMID:19536289

  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

    2005-04-19

    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

  3. 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.

  4. Spatial profile of thermoelectric effects during Peltier pulsing in Bi and Bi/MnBi eutectic

    NASA Technical Reports Server (NTRS)

    Silberstein, R. P.; Larson, D. J., Jr.

    1987-01-01

    The spatial profile of the thermal transients that occur during and following the current pulsing associated with Peltier Interface Demarcation during directional solidification is studied. Results for pure Bi are presented in detail and compared with corresponding results for the Bi/MnBi eutectic. Significant thermal transients occur throughout the sample that can be accounted for by the Peltier effect, the Thomson effect, and Joule heating. These effects are separated and their behavior is studied as a function of time, current density, and position with respect to the solid/liquid interface.

  5. CD83 Modulates B Cell Activation and Germinal Center Responses.

    PubMed

    Krzyzak, Lena; Seitz, Christine; Urbat, Anne; Hutzler, Stefan; Ostalecki, Christian; Gläsner, Joachim; Hiergeist, Andreas; Gessner, André; Winkler, Thomas H; Steinkasserer, Alexander; Nitschke, Lars

    2016-05-01

    CD83 is a maturation marker for dendritic cells. In the B cell lineage, CD83 is expressed especially on activated B cells and on light zone B cells during the germinal center (GC) reaction. The function of CD83 during GC responses is unclear. CD83(-/-) mice have a strong reduction of CD4(+) T cells, which makes it difficult to analyze a functional role of CD83 on B cells during GC responses. Therefore, in the present study we generated a B cell-specific CD83 conditional knockout (CD83 B-cKO) model. CD83 B-cKO B cells show defective upregulation of MHC class II and CD86 expression and impaired proliferation after different stimuli. Analyses of GC responses after immunization with various Ags revealed a characteristic shift in dark zone and light zone B cell numbers, with an increase of B cells in the dark zone of CD83 B-cKO mice. This effect was not accompanied by alterations in the level of IgG immune responses or by major differences in affinity maturation. However, an enhanced IgE response was observed in CD83 B-cKO mice. Additionally, we observed a strong competitive disadvantage of CD83-cKO B cells in GC responses in mixed bone marrow chimeras. Furthermore, infection of mice with Borrelia burgdorferi revealed a defect in bacterial clearance of CD83 B-cKO mice with a shift toward a Th2 response, indicated by a strong increase in IgE titers. Taken together, our results show that CD83 is important for B cell activation and modulates GC composition and IgE Ab responses in vivo. PMID:26983787

  6. 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

  7. Detection of Foreign Antigen-specific CD4+Foxp3+ Regulatory T Cells by MHC Class II Tetramer and Intracellular CD154 Staining

    PubMed Central

    Choi, Jin Young

    2013-01-01

    The unrestricted population of CD4+Foxp3+ regulatory T (Treg) cells, which have been known to control the expression of autoimmune diseases and protective immunity to inflammatory reactions, has led to greater appreciation of functional plasticity. Detecting and/or isolating Ag-specific CD4+Foxp3+ Tregs at the single cell level are required to study their function and plasticity. In this study, we established and compared both MHC class II tetramer and intracellular CD154 staining, in order to detect CD4+Foxp3+ Treg specific for foreign Ag in acute and chronic infections with lymphocytic choriomeningitis virus (LCMV). Our results revealed that MHC class II tetramer staining showed a lower detection rate of LCMV GP66-77-specific CD4+ T cells because most of MHC class II tetramers were unbound and unstable when combined staining was performed with intracellular cytokines. In contrast, intracellular CD154 staining was revealed to be easier and simple for detecting LCMV GP66-77-specific CD4+ T cells, compared to MHC class II tetramer staining. Subsequently, we employed intracellular CD154 staining to detect LCMV GP66-77-specific CD4+Foxp3+ Tregs using Foxp3GFP knock-in mouse, and found that LCMV GP66-77-specific CD4+Foxp3+ Tregs and polyclonal CD4+Foxp3+ Tregs showed differential expansion in mice infected with LCMV Arms or Cl13 at acute (8 and 13 days pi) and chronic phases (35 days pi). Therefore, our results provide insight into the valuable use of intracellular CD154 staining to detect and characterize foreign Ag-specific CD4+Foxp3+ Treg in various models. PMID:24385945

  8. 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…

  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. 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.

  11. Dendritic cell vaccine modified by Ag85A gene enhances anti-tumor immunity against bladder cancer.

    PubMed

    Zhang, Pei; Wang, Jinyan; Wang, Danan; Wang, Huan; Shan, Fengping; Chen, Liudan; Hou, Ying; Wang, Enhua; Lu, Chang-Long

    2012-11-01

    The ability of dendritic cells to provide all the signals required for T-cell activation makes them an ideal cancer vaccine platform. With the use of established DC2.4 cell line, originated from C57BL/6 mice and developed by superinfecting GM-CSF transduced bone marrow cells with myc and raf oncogenes, we investigated whether the DC 2.4 cell line transfected with Ag85A gene could enhance immunity against bladder cancer. Both phenotypic and functional analyses of Ag85A-DCs were done with use of FCM and T cell proliferation test. The cytotoxicity of Ag85A-DCs loaded with tumor cell lysate was verified by LDH. Finally, the production of interferon gamma was assayed by both ELISA and FCM. The immunotherapeutic effect of DC vaccine on murine bladder cancer was assessed pharmacologically and pathologically. Our results showed that Ag85A gene transfected DCs expressed high levels of key surface markers such as CD80, CD86 and MHC-II. The CTL primed with MB49 lysate-pulsed Ag85A-DCs elicits higher activity against MB49 tumor cells and upregulated level of IFN-γ production. Furthermore, the significant inhibitive effect on tumor growth in mice was found in the group of Ag85A-DC vaccine. The infiltration of CD4(+) or CD8(+) T cell within established tumor treated by Ag85A-DC vaccine significantly increased as compared with control groups. It is therefore concluded that DCs engineered by Ag85A gene exerts enhanced anti-tumor immunity against bladder cancer and this study might provide a meaningful mode of action with the use of Ag85A engineered DC vaccination in anti-cancer immunotherapy. PMID:22884511

  12. Magnesium and cadmium containing Heusler phases REPd2Mg, REPd2Cd, REAg2Mg, REAu2Mg and REAu2Cd

    NASA Astrophysics Data System (ADS)

    Johnscher, Michael; Stein, Sebastian; Niehaus, Oliver; Benndorf, Christopher; Heletta, Lukas; Kersting, Marcel; Höting, Christoph; Eckert, Hellmut; Pöttgen, Rainer

    2016-02-01

    Twenty-eight new Heusler phases REPd2Mg, REPd2Cd, REAg2Mg, REAu2Mg and REAu2Cd with different rare earth elements were synthesized from the elements in sealed niobium ampoules in a water-cooled sample chamber of an induction furnace. The samples were characterized by powder X-ray diffraction. The cell volumes show the expected lanthanide contraction. The structures of YPd2Cd, GdPd2Cd, GdAu2Cd, Y1.12Ag2Mg0.88 and GdAg2Mg were refined based on single crystal diffractometer data. The magnetic properties were determined for fifteen phase pure samples. LuAu2Mg is a weak Pauli paramagnet with a susceptibility of 1.0(2) × 10-5 emu mol-1 at room temperature. The remaining samples show stable trivalent rare earth ions and most of them order magnetically at low temperatures. The ferromagnet GdAg2Mg shows the highest ordering temperature of TC = 98.3 K. 113Cd and 89Y MAS NMR spectra of YAu2Cd and YPd2Cd confirm the presence of unique crystallographic sites. The resonances are characterized by large Knight shifts, whose magnitude can be correlated with electronegativity trends.

  13. Gut Microbial Membership Modulates CD4 T Cell Reconstitution and Function after Sepsis.

    PubMed

    Cabrera-Perez, Javier; Babcock, Jeffrey C; Dileepan, Thamotharampillai; Murphy, Katherine A; Kucaba, Tamara A; Badovinac, Vladimir P; Griffith, Thomas S

    2016-09-01

    Transient lymphopenia is one hallmark of sepsis, and emergent data indicate the CD4 T cell compartment in sepsis survivors is numerically and functionally altered (when examined at the Ag-specific level) compared with nonseptic control subjects. Previous data from our laboratory demonstrated Ag-independent, lymphopenia-induced homeostatic proliferation to be a contributing mechanism by which CD4 T cells numerically recover in sepsis survivors. However, we reasoned it is also formally possible that some CD4 T cells respond directly to Ag expressed by gut-resident microbes released during polymicrobial sepsis. The effect of gut microbiome leakage on CD4 T cells is currently unknown. In this study, we explored the number and function of endogenous CD4 T cells specific for segmented filamentous bacterium (SFB) after cecal ligation and puncture (CLP)-induced sepsis using mice that either contained or lacked SFB as a normal gut-resident microbe. Interestingly, SFB-specific CD4 T cells underwent Ag-driven proliferation in CLP-treated SFB(+), but not in SFB(-), mice. Moreover, CLP-treated SFB(+) mice showed resistance to secondary lethal infection with recombinant SFB Ag-expressing virulent Listeria (but not wild-type virulent Listeria), suggesting the CLP-induced polymicrobial sepsis primed for a protective response by the SFB-specific CD4 T cells. Thus, our data demonstrate that the numerical recovery and functional responsiveness of Ag-specific CD4 T cells in sepsis survivors is, in part, modulated by the intestinal barrier's health discreetly defined by individual bacterial populations of the host's microbiome. PMID:27448587

  14. Dual effect of CD85/leukocyte Ig-like receptor-1/Ig-like transcript 2 and CD152 (CTLA-4) on cytokine production by antigen-stimulated human T cells.

    PubMed

    Saverino, Daniele; Merlo, Andrea; Bruno, Silvia; Pistoia, Vito; Grossi, Carlo E; Ciccone, Ermanno

    2002-01-01

    The functional outcome of a T cell response to Ag is the result of a balance between coactivation and inhibitory signals. In this study we have investigated the effects of the CD85/leukocyte Ig-like receptor (LIR)-1/Ig-like transcript (ILT) 2 and of CD152 (CTLA-4) inhibitory receptors on the modulation of cell-mediated immune responses to specific Ags, both at the effector and at the resting/memory cell level. Proliferation and cytokine production of CD4+ T lymphocytes stimulated by recall Ags have been evaluated. Cross-linking of CD85/LIR-1/ILT2 or CD152 molecules on cultured T cells using specific mAb and goat anti-mouse antiserum inhibits Ag-specific T cell proliferation. This inhibition is always paralleled by increased production of cytokines that down-regulate immune responses, e.g., IL-10 and TGF-beta. In contrast, the production of cytokines that support T cell expansion and function (e.g., IL-2, IFN-gamma, and IL-13) is significantly decreased. A long-term effect of CD85/LIR-1/ILT2 and of CD152 occurs during Ag-specific T cell activation and expansion. T cells, primed in the presence of anti-CD85/LIR-1/ILT2 and anti-CD152 blocking mAb (but in the absence of cross-linking), proliferate at higher rates and produce higher amounts of IL-2, IFN-gamma, and IL-13, in comparison with T cells stimulated with the Ag alone. We also show that the inhibitory receptors exert a similar effect during Ag activation of specific CD4+ effector T cells. Ag-specific polyclonal CD4+ T cell lines exhibit increased proliferation and IL-2, IFN-gamma, and IL-13 production when the CD85/LIR-1/ILT2 receptor is blocked by specific mAb. In contrast, cross-linking of this receptor down-regulates Ag-specific CD4+ T cell proliferation and increases IL-10 and TGF-beta production. PMID:11751964

  15. In situ synthesis of CdS/CdWO4/WO3 heterojunction films with enhanced photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Zhan, Faqi; Li, Jie; Li, Wenzhang; Yang, Yahui; Liu, Wenhua; Li, Yaomin

    2016-09-01

    CdS/CdWO4/WO3 heterojunction films on fluorine-doped tin oxide (FTO) substrates are for the first time prepared as an efficient photoanode for photoelectrochemical (PEC) hydrogen generation by an in situ conversion process. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible spectrometry (UV-vis) and X-ray photoelectron spectroscopy (XPS). The CdS hollow spheres (∼80 nm) sensitized WO3 plate film with a CdWO4 buffer-layer exhibits increased visible light absorption and a significantly improved photoelectrochemical performance. The photocurrent density at 0 V (vs. Ag/AgCl) of the CdS/CdWO4/WO3 anode is ∼3 times higher than that of the CdWO4/WO3 anode, and ∼9 times higher than that of pure WO3 under illumination. The highest incident-photon-to-current-efficiency (IPCE) value increased from 16% to 63% when the ternary heterojunction was formed. This study demonstrates that the synthesis of ternary composite photocatalysts by the in situ conversion process may be a promising approach to achieve high photoelectric conversion efficiency.

  16. Growth of CdTe thin films on graphene by close-spaced sublimation method

    SciTech Connect

    Jung, Younghun; Yang, Gwangseok; Kim, Jihyun; Chun, Seungju; Kim, Donghwan

    2013-12-02

    CdTe thin films grown on bi-layer graphene were demonstrated by using the close-spaced sublimation method, where CdTe was selectively grown on the graphene. The density of the CdTe domains was increased with increasing the number of the defective sites in the graphene, which was controlled by the duration of UV exposure. The CdTe growth rate on the bi-layer graphene electrodes was 400 nm/min with a bandgap energy of 1.45–1.49 eV. Scanning electron microscopy, micro-Raman spectroscopy, micro-photoluminescence, and X-ray diffraction technique were used to confirm the high quality of the CdTe thin films grown on the graphene electrodes.

  17. Antigen-dependent and –independent contributions to primary memory CD8 T cell activation and protection following infection

    PubMed Central

    Martin, Matthew D.; Badovinac, Vladimir P.

    2015-01-01

    Memory CD8 T-cell activation, including expression of IFN-γ and granzymeB, can be induced by antigen (Ag)-dependent signals through the T-cell-receptor, or by pathogen-derived inflammatory cytokines in an Ag-independent manner. Recent studies have come to conflicting results regarding the contributions of Ag and/or inflammation to memory CD8 T-cell activation. Additionally, research has indicated that inflammation-driven CD8 T-cell responses during un-related infections (bystander activation) have the potential to provide protection, but whether protection occurs in immuno-competent hosts is unclear. To investigate these questions, we examined activation of virus-specific memory CD8 T-cells following infection with L. monocytogenes either expressing or not cognate Ag. We show that Ag and inflammation act synergistically in vitro to induce memory activation. In vivo, we found that when memory CD8 T-cells significantly contribute to clearance of infection, early activation and continued responses by these cells are enhanced by cognate Ag recognition. Mechanistically, we show that bystander responses by memory are dependent upon the dose of infection and the amount of inflammation elicited following infection and are able to provide protection in IFN-γ deficient mice, but not in immuno-competent hosts. The data elucidate the requirements for memory CD8 T-cell activation and the protective role of bystander responses. PMID:26658291

  18. Rational Design of Bi Nanoparticles for Efficient Electrochemical CO2 Reduction: The Elucidation of Size and Surface Condition Effects

    DOE PAGESBeta

    Zhang, Zhiyong; Chi, Miaofang; Veith, Gabriel M.; Zhang, Pengfei; Lutterman, Daniel A.; Rosenthal, Joel; Overbury, Steven H.; Dai, Sheng; Zhu, Huiyuan

    2016-08-08

    Here we report an efficient electrochemical conversion of CO2 to CO on surface-activated bismuth nanoparticles (NPs) in acetonitrile (MeCN) under ambient conditions, with the assistance of 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim][OTf]). Through the comparison between electrodeposited Bi films (Bi-ED) and different types of Bi NPs, we, for the first time, demonstrate the effects of catalyst’s size and surface condition on organic phase electrochemical CO2 reduction. Our study reveals that the surface inhibiting layer (hydrophobic surfactants and Bi3+ species) formed during the synthesis and purification process hinders the CO2 reduction, leading to a 20% drop in Faradaic efficiency for CO evolution (FECO). Bimore » particle size showed a significant effect on FECO when the surface of Bi was air-oxidized, but this effect of size on FECO became negligible on surface-activated Bi NPs. After the surface activation (hydrazine treatment) that effectively removed the native inhibiting layer, activated 36-nm Bi NPs exhibited an almost-quantitative conversion of CO2 to CO (96.1% FECO), and a mass activity for CO evolution (MACO) of 15.6 mA mg–1, which is three-fold higher than the conventional Bi-ED, at ₋2.0 V (vs Ag/AgCl). Ultimately, this work elucidates the importance of the surface activation for an efficient electrochemical CO2 conversion on metal NPs and paves the way for understanding the CO2 electrochemical reduction mechanism in nonaqueous media.« less

  19. Improved Bi Film Wrapped Single Walled Carbon Nanotubes for Ultrasensitive Electrochemical Detection of Trace Cr(VI)

    PubMed Central

    Zhou, Shilin; Xue, Zi-Ling; Xu, Lina; Gu, Yingying; Miao, Yuqing

    2014-01-01

    We report here the successful fabrication of an improved Bi film wrapped single walled carbon nanotubes modified glassy carbon electrode (Bi/SWNTs/GCE) as a highly sensitive platform for ultratrace Cr(VI) detection through catalytic adsorptive cathodic stripping voltammetry (AdCSV). The introduction of negatively charged SWNTs extraordinarily decreased the size of Bi particles to nanoscale due to electrostatic interaction which made Bi(III) cations easily attracted onto the surface of SWNTs in good order, leading to higher quality of Bi film deposition. The obtained Bi/SWNTs composite was well characterized with electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), the static water contact angle and the voltammetric measurements. The results demonstrates the improvements in the quality of Bi film deposited on the surface of SWNTs such as faster speed of electron transfer, more uniform and smoother morphology, better hydrophilicity and higher stripping signal. Using diethylene triaminepentaacetic acid (DTPA) as complexing ligand, the fabricated electrode displays a well-defined and highly sensitive peak for the reduction of Cr(III)-DTPA complex at −1.06 V (vs. Ag/AgCl) with a linear concentration range of 0–25 nM and a fairly low detection limit of 0.036 nM. No interference was found in the presence of coexisting ions, and good recoveries were achieved for the analysis of a river sample. In comparison to previous approaches using Bi film modified GCE, the newly designed electrode exhibits better reproducibility and repeatability towards aqueous detection of trace Cr(VI) and appears to be very promising as the basis of a highly sensitive and selective voltammetric procedure for Cr(VI) detection at trace level in real samples. PMID:24771881

  20. Growth of nucleation sites on Pb-doped Bi2Sr2Ca1Cu2O8 + delta

    NASA Astrophysics Data System (ADS)

    Finnemore, D. K.; Xu, Ming; Kouzoudis, D.; Bloomer, T.; Kramer, M. J.; McKernan, Stuart; Balachandran, U.; Haldar, Pradeep

    1996-01-01

    In the growth of Bi2Sr2Ca2Cu3O10+δ from mixed powders of Pb-doped Bi2Sr2Ca1Cu2O8+δ and other oxides, it has been discovered that a dense array of hillocks or mesas grow at the interface between a Ag overlay and Pb-doped Bi2Sr2Ca1Cu2O8+δ grains during the ramp up to the reaction temperature. As viewed in an environmental scanning electron microscope, the Ag coated grains develop a texture that looks like ``chicken pox'' growing on the grains at about 700 °C. These hillocks are about 100 nm across and are spaced at about 500 to 1000 nm. If there is no Ag, this texture does not develop. Preliminary measurements indicate that the hillocks are a recrystallization of (Bi,Pb)2Sr2Ca1Cu2O8+δ, and are definitely not a Pb rich phase.

  1. Producing CD-ROMs.

    ERIC Educational Resources Information Center

    Hyams, Peter, Ed.

    1992-01-01

    This issue presents 11 articles that address issues relating to the production of CD-ROMs. Highlights include current uses of CD-ROM; standards; steps involved in producing CD-ROMs, including data capture, conversion, and tagging, product design, and indexing; authoring; selecting indexing and retrieval software; costs; multimedia CD-ROMs; and…

  2. CD14+CD16+ and CD14+CD163+ monocyte subpopulations in kidney allograft transplantation

    PubMed Central

    2014-01-01

    Background Monocytes represent a heterogeneous population of cells subdivided according to the expression level of membrane antigens. A pro-inflammatory (intermediate/nonclassical) subpopulation of monocytes is defined by expression of CD16. CD163 seems to be characteristically preferentially expressed by immunosuppressive monocytes. The aim of our study was to evaluate the distribution of monocyte subpopulations in 71 patients with kidney allograft transplantation. Results The phenotype was evaluated by flow cytometry in defined time points. The proportions of peripheral CD14+CD16+ monocytes were downregulated immediately after the kidney transplantation and basiliximab treatment partially attenuated this trend. The transient downregulation of the CD14+CD16+ subpopulation was adjusted to basal values in two months. The proportions of CD14+CD163+ monocytes were transiently upregulated early after the kidney transplantation and remained higher during the first month in most patients. In ATG treated patients, the expansion of CD14+CD163+ monocytes was delayed but their upregulation lasted longer. In vitro data showed the direct effect of ATG and methylprednisolone on expression of CD16 and CD163 molecules while basiliximab did not affect the phenotype of cultured monocytes. Conclusions We assume from our data that kidney allograft transplantation is associated with modulation of monocyte subpopulations (CD14+CD16+ and CD14+CD163+) partially affected by an immunosuppressive regime used. PMID:24499053

  3. 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.

  4. 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

  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. Stable core/shell CdTe/Mn-CdS quantum dots sensitized three-dimensional, macroporous ZnO nanosheet photoelectrode and their photoelectrochemical properties.

    PubMed

    Li, Weili; Sheng, Pengtao; Feng, Hongyan; Yin, Xuehua; Zhu, Xuewei; Yang, Xu; Cai, Qingyun

    2014-08-13

    A novel photoelectrode based on ZnS/CdTe/Mn-CdS/ZnS-sensitized three-dimensional macroporous ZnO nanosheet (NS) has been prepared by electrodeposition and successive ion layer adsorption and reaction (SILAR) method. The photoelectrode performances were significantly improved through the coupling of the core/shell CdTe/Mn-CdS quantum dots (QDs) with ZnO NS, and the introduction of the ZnS layer as a potential barrier. The photocurrent density systematically increases from ZnO NS (0.45 mA/cm(2)), CdTe/Mn-CdS/ZnO NS (4.98 mA/cm(2)), to ZnS/CdTe/Mn-CdS/ZnS/ZnO (6.23 mA/cm(2)) under the irradiation of AM 1.5G simulated sunlight. More important, the ZnS/CdTe/Mn-CdS/ZnS-sensitized ZnO NS photoelectrode provides a remarkable photoelectrochemical cell efficiency of 4.20% at -0.39 V vs Ag/AgCl. PMID:25010851

  7. Geochemistry of the Patricia Zn-Pb-Ag Deposit (paguanta, NE Chile)

    NASA Astrophysics Data System (ADS)

    Chinchilla Benavides, D.; Merinero Palomares, R.; Piña García, R.; Ortega Menor, L.; Lunar Hernández, R.

    2013-12-01

    The Patricia Zn-Pb-Ag ore deposit is located within the Paguanta mining project, situated at the northern end of the Andean Oligocene Porphyry Copper Belt of Chile. The sulfide mineralization occurs as W-E oriented veins hosted in volcanic rocks, mainly andesite (pyroclastic, ash and lavas), of Upper Cretaceous to Middle Tertiary age. The ore mineralogy (obtained by EMPA analyses) comprises in order of abundance, pyrite, sphalerite (5.5 - 10.89 wt % Fe, 9.8-19 % molar FeS and 0.52 wt % Cd), galena, arsenopyrite, chalcopyrite and Ag-bearing sulfosalts. The veins show a zoned and banded internal structure with pyrite at the edges and sphalerite in the center. The Ag occurs mostly as Ag-Cu-Sb sulfosalts, in order of abundance: series freibergite - argentotennantite -polybasite and stephanite. Other minor Ag phases such as argentite, pyrargirite and diaphorite were also identified. These Ag phases are typically associated with the base-metal sulfides. Freibergite occurs filling voids within sphalerite, chalcopyrite and at the contact between sphalerite and galena. Polybasite, stephanite, pyrargirite and argentite are mostly in close association with freibergite. In the case of diaphorite, it commonly occurs filling voids between galena crystals or as inclusions within galena. Some minor Ag-bearing sulfosalts are also identified between pyrite crystals. The alteration minerals are dominated by chlorite, illite and kaolinite. The gangue minerals consist of quartz and carbonates identified by XRD as kutnahorite. We obtained linear correlation statistically significant only for Ag, As Au, Cd, Cu, Pb, Sb and Zn and therefore we generated an enhanced scatter plot matrix of these elements. Bulk rock analyses (ICP/MS and XRF) of drill cores show that Ag is strongly and positively correlated with Pb and As, moderately with Cd, Sb, Au and Zn and weakly with Cu, while Au is moderately and positively correlated with Ag, As, Cd, Sb and Zn and weakly with Cu and Pb. These results

  8. The novel phase transition of NaBi(WO{sub 4}){sub 2} under high pressure

    SciTech Connect

    Ma, Chunli; Cui, Hang; Li, Fangfei; Wang, Jingshu; Wu, Xiaoxin; Zhang, Jian; Zhou, Qiang; Liu, Jinghe; Cui, Qiliang

    2013-04-15

    The Raman and synchrotron angle-dispersive X-ray diffraction studies have been performed on NaBi(WO{sub 4}){sub 2} under high pressure up to 30.7 and 36.2 GPa, respectively, at room temperature. With pressure increases to ∼7.0 GPa, the structure of NaBi(WO{sub 4}){sub 2} begins to transform from tetragonal (I4{sub 1}/a) into monoclinic (P2/m), and the phase transition completes around 13 GPa. With pressure higher than 29.0 GPa, the NaBi(WO{sub 4}){sub 2} turns into amorphous state. The random arrangement of Na{sup +} and Bi{sup 3+} in short-range ordered scheelite NaBi(WO{sub 4}){sub 2} results in the tetragonal to monoclinic phase transition, which is different from that observed in AWO{sub 4} tungstates and AMoO{sub 4} molybdates (A=Ca, Sr, Ba, Pb, Eu, Cd). - Graphical abstract: The NaBi(WO{sub 4}){sub 2} transforms from tetragonal into monoclinic, which starts around 7 GPa and completes at about 13 GPa. With pressure higher than 29 GPa, the NaBi(WO{sub 4}){sub 2} turns into amorphous state. Highlights: ► Raman and X-ray diffraction studies performed on NaBi(WO{sub 4}){sub 2} up to 30.7 and 36.2 GPa, respectively. ► The tetragonal (I4{sub 1}/a) into monoclinic (P2/m) phase transition is determined. ► With pressure higher than 29 GPa, the NaBi(WO{sub 4}){sub 2} ultimately turns into amorphous state. ► The ambient pressure bulk modulus and volume of tetragonal and monoclinic phases are obtained.

  9. Multivalency and polaronic hole trapping in BaBiO3

    NASA Astrophysics Data System (ADS)

    Franchini, Cesare

    2010-03-01

    The phase diagrams of hole-doped oxides have been one of the central issues of condensed-matter physics in the last 20 years. Whereas transition metal oxides are now fairly well understood, the physics of the conceivably ``simpler'' sp bonded oxides is less clear. How is it possible that some of these oxides remain insulating upon doping? By adopting hybrid density functional theory and self-consistent GW we show that the multivalency of the metal cations and the formation of polaronic lattice distortions (i.e the coupling between holes/electrons trapping on specific lattice sites and the accompanying polarization field) can explain this puzzling experimental observation. The example we have chosen is BaBiO3, which remains an insulator upon moderate hole doping and undergoes an insulator to superconductor transition around a hole concentration of 0.35. Pure BaBiO3 is characterized by a charge disproportionation (CD) with half of the Bi atoms possessing a valence 3+ and half a valence 5+. The CD goes in hand with significant structural and electronic changes from the ideal metallic cubic perovskite crystal (BaBi^4+O3) towards an insulating monoclinic structure (Ba2Bi^3+Bi^5+O6) characterized by a charge density wave state formed by alternating breathing-in/out distortions of oxygen octahedra around inequivalent Bi^5+/Bi^3+ ions [1]. Our results show that upon-hole doping Bi^3+ sites trap two holes from the valence band to form Bi^5+ cations, and that the trapping is accompanied by a distortion of the oxygen polarization field that surround the BiO6 octahedra. We show that the strong interaction between polarons ultimately causes an overlap between the polaronic band and the valence band resulting in a metallic non-disproportionated state [2]. [4pt] [1] C. Franchini, A. Sanna, M. Marsman & G. Kresse, arXiv:0803.0619v2 (2009).[0pt] [2] C. Franchini, G. Kresse & R. Podloucky, PRL 102, 256402 (2009).

  10. Heterologous vaccination against human tuberculosis modulates antigen-specific CD4+ T-cell function.

    PubMed

    Dintwe, One B; Day, Cheryl L; Smit, Erica; Nemes, Elisa; Gray, Clive; Tameris, Michele; McShane, Helen; Mahomed, Hassan; Hanekom, Willem A; Scriba, Thomas J

    2013-09-01

    Heterologous prime-boost strategies hold promise for vaccination against tuberculosis. However, the T-cell characteristics required for protection are not known. We proposed that boost vaccines should induce long-lived functional and phenotypic changes to T cells primed by Bacille Calmette Guerin (BCG) and/or natural exposure to mycobacteria. We characterized changes among specific CD4(+) T cells after vaccination with the MVA85A vaccine in adults, adolescents, and children. CD4(+) T cells identified with Ag85A peptide-bearing HLA class II tetramers were characterized by flow cytometry. We also measured proliferative potential and cytokine expression of Ag85A-specific CD4(+) T cells. During the effector phase, MVA85A-induced specific CD4(+) T cells coexpressed IFN-γ and IL-2, skin homing integrins, and the activation marker CD38. This was followed by contraction and a transition to predominantly IL-2-expressing, CD45RA(-) CCR7(+) CD27(+) or CD45RA(+) CCR7(+) CD27(+) specific CD4(+) T cells. These surface phenotypes were similar to Ag85A-specific T cells prior to MVA85A. However, functional differences were observed postvaccination: specific proliferative capacity was markedly higher after 6-12 months than before vaccination. Our data suggest that MVA85A vaccination may modulate Ag85A-specific CD4(+) T-cell function, resulting in greater recall potential. Importantly, surface phenotypes commonly used as proxies for memory T-cell function did not associate with functional effects of vaccination. PMID:23737382

  11. Quaternary heterostructured Ag–Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}/Bi{sub 2}MoO{sub 6} composite: Synthesis and enhanced visible-light-driven photocatalytic activity

    SciTech Connect

    Lin, Xue; Guo, Xiaoyu; Shi, Weilong; Zhai, Hongju; Yan, Yongsheng; Wang, Qingwei

    2015-09-15

    In this work, a novel quaternary heterostructured Ag–Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}/Bi{sub 2}MoO{sub 6} composite was fabricated through a low-temperature solution-phase route. The XRD, SEM, EDX and XPS results indicated the as-prepared sample is a four-phase composite of Bi{sub 2}O{sub 2}CO{sub 3}, Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}, Bi{sub 2}MoO{sub 6}, and Ag. The photocatalytic activities of the as-synthesized samples were evaluated towards the degradation of phenol red aqueous solution. The results showed that the as-synthesized Ag–Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}/Bi{sub 2}MoO{sub 6} photocatalysts displayed much higher photocatalytic activities in comparison with pure Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}, pure Bi{sub 2}MoO{sub 6}, and Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}/Bi{sub 2}MoO{sub 6} composite. Among them, the 2.5% Ag–Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}/Bi{sub 2}MoO{sub 6} sample performed the best. The enhanced photocatalytic activity of the composite photocatalyst was attributed predominantly to the efficient separation of photoinduced electrons and holes. In addition, Ag nanoparticles were photodeposited on the surface of the composite to increase visible-light absorption via the surface plasmon resonance, which is also beneficial to the enhancement of photocatalytic performance. The possible photocatalytic mechanism of the quaternary heterostructure was also discussed in detail. - Graphical abstract: Quaternary heterostructured Ag–Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}/Bi{sub 2}MoO{sub 6} were fabricated. The as-synthesized Ag–Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}/Bi{sub 2}MoO{sub 6} photocatalysts displayed much higher photocatalytic activities in comparison with pure Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}, pure Bi{sub 2}MoO{sub 6}, and Bi{sub 3.64}Mo{sub 0.36}O{sub 6.55}/Bi{sub 2}MoO{sub 6} composite

  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. Generalized bi-circular projections

    NASA Astrophysics Data System (ADS)

    Lin, Pei-Kee

    2008-04-01

    Recall that a projection P on a complex Banach space X is a generalized bi-circular projection if P+[lambda](I-P) is a (surjective) isometry for some [lambda] such that [lambda]=1 and [lambda][not equal to]1. It is easy to see that every hermitian projection is generalized bi-circular. A generalized bi-circular projection is said to be nontrivial if it is not hermitian. Botelho and Jamison showed that a projection P on C([0,1]) is a nontrivial generalized bi-circular projection if and only if P-(I-P) is a surjective isometry. In this article, we prove that if P is a projection such that P+[lambda](I-P) is a (surjective) isometry for some [lambda], then either P is hermitian or [lambda] is an nth unit root of unity. We also show that for any nth unit root [lambda] of unity, there are a complex Banach space X and a nontrivial generalized bi-circular projection P on X such that P+[lambda](I-P) is an isometry.

  14. Microstructure Of MnBi/Bi Eutectic Alloy

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Eisa, G. F.; Baskaran, B.; Richardson, Donald C.

    1988-01-01

    Collection of three reports describes studies of directional solidification of MnBi/Bi eutectic alloy. Two of the reports, "Influence of Convection on Lamellar Spacing of Eutectics" and "Influence of Convection on Eutectic Microstructure," establish theoretical foundation for remaining document. Reports seek to quantify effect of convection on concentration field of growing lamellar eutectic. Remaining report, "Study of Eutectic Formation," begins by continuing theoretical developments. New technique under development by one of the authors helps to reveal three-dimensional microstructures of alloys.

  15. Graphene oxide/α-Bi(2)O(3) composites for visible-light photocatalysis, chemical catalysis, and solar energy conversion.

    PubMed

    Som, Tirtha; Troppenz, Gerald V; Wendt, R Robert; Wollgarten, Markus; Rappich, Jörg; Emmerling, Franziska; Rademann, Klaus

    2014-03-01

    The growing challenges of environmental purification by solar photocatalysis, precious-metal-free catalysis, and photocurrent generation in photovoltaic cells receive the utmost global attention. Here we demonstrate a one-pot, green chemical synthesis of a new stable heterostructured, ecofriendly, multifunctional microcomposite that consists of α-Bi2 O3 microneedles intercalated with anchored graphene oxide (GO) microsheets (1.0 wt %) for the above-mentioned applications on a large economical scale. The bare α-Bi2 O3 microneedles display two times better photocatalytic activities than commercial TiO2 (Degussa-P25), whereas the GO-hybridized composite exhibits approximately four to six times enhanced photocatalytic activities than the neat TiO2 photocatalyst in the degradation of colored aromatic organic dyes (crystal violet and rhodamine 6G) under visible-light irradiation (300 W tungsten lamp). The highly efficient activity is associated with the strong surface adsorption ability of GO for aromatic dye molecules, the high carrier acceptability, and the efficient electron-hole pair separation in Bi2 O3 by individual adjoining GO sheets. The introduction of Ag nanoparticles (2.0 wt %) further enhances the photocatalytic performance of the composite over eightfold because of a plasmon-induced electron-transfer process from Ag nanoparticles through the GO sheets into the conduction band of Bi2 O3 . The new composites are also catalytically active and catalyze the reduction of 4-nitrophenol to 4-aminophenol in the presence of borohydride ions. Photoanodes assembled from GO/α-Bi2 O3 and Ag/GO/α-Bi2 O3 composites display an improved photocurrent response (power conversion efficiency ∼20 % higher) over those prepared without GO in dye-sensitized solar cells. PMID:24578169

  16. Bismuth zinc vanadate, BiZn{sub 2}VO{sub 6}: New crystal structure type and electronic structure

    SciTech Connect

    Eliziario Nunes, Sayonara; Wang, Chun-Hai; So, Karwei; Evans, John S.O.; Evans, Ivana Radosavljević

    2015-02-15

    We report a combined experimental and computational study of the crystal structure and electronic properties of bismuth zinc vanadate, BiZn{sub 2}VO{sub 6}, known for its visible light photocatalytic activity. The crystal structure has been solved from laboratory powder X-ray diffraction data using the repeated minimisations from random starting values method. BiZn{sub 2}VO{sub 6} adopts a new structure type, based on the following building blocks: corner- and edge-sharing ZnO{sub 4} tetrahedra, ZnO{sub 6} octahedra and VO{sub 4} tetrahedra, and Bi{sub 2}O{sub 12} dimers. It is the only known member of the BiM{sub 2}AO{sub 6} (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family which does not appear to be structurally closely related to others. The electronic structure of BiZn{sub 2}VO{sub 6}, calculated by DFT methods, shows that it is an indirect gap semiconductor with a calculated band gap of 1.6 eV, which compares favourably to the experimentally measured value of 2.4 eV. - Graphical abstract: The crystal structure of BiZn{sub 2}VO{sub 6}, a new structure type in the BiM{sub 2}AO{sub 6} (M=Mg, Ca, Cd, Cu, Pb, Mn, Zn; A=V, P, As) family. - Highlights: • Structure solution from PXRD data by repeated minimisations from random starting values. • New structure type in the BiM{sub 2}AO{sub 6} (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family. • Electronic structure calculation.

  17. BiOI/TiO2-nanorod array heterojunction solar cell: Growth, charge transport kinetics and photoelectrochemical properties

    NASA Astrophysics Data System (ADS)

    Wang, Lingyun; Daoud, Walid A.

    2015-01-01

    A series of BiOI/TiO2-nanorod array photoanodes were grown on fluorine-doped tin oxide (FTO) glass using a simple two-step solvothermal/hydrothermal method. The effects of the hydrothermal process, such as TiO2 nanorod growth time, BiOI concentration and the role of surfactant, polyvinylpyrrolidone (PVP), on the growth of BiOI, were investigated. The heterojunctions were characterized by X-ray diffraction, UV-vis absorbance spectroscopy and scanning electron microscopy. The photoelectrochemical properties of the as-grown junctions, such as linear sweep voltammetry (LSV) behavior, photocurrent response and incident photon-to-electron conversion efficiency (IPCE) under Xenon lamp illumination, are presented. The cell with BiOI/TiO2 (PVP) as photoanode can reach a short current density (Jsc) of 0.13 mA/cm2 and open circuit voltage (Voc) of 0.46 V vs. Ag/AgCl under the irradiation of a 300 W Xenon lamp. Compared to bare TiO2, the IPCE of BiOI/TiO2 (PVP) increased 4-5 times at 380 nm. Furthermore, the charge transport kinetics within the heterojunction is also discussed.

  18. NK Cells Help Induce Anti-Hepatitis B Virus CD8+ T Cell Immunity in Mice.

    PubMed

    Zheng, Meijuan; Sun, Rui; Wei, Haiming; Tian, Zhigang

    2016-05-15

    Although recent clinical studies demonstrate that NK cell function is impaired in hepatitis B virus (HBV)-persistent patients, whether or how NK cells play a role in anti-HBV adaptive immunity remains to be explored. Using a mouse model mimicking acute HBV infection by hydrodynamic injection of an HBV plasmid, we observed that although serum hepatitis B surface Ag and hepatitis B envelope Ag were eliminated within 3 to 4 wk, HBV might persist for >8 wk in CD8(-/-) mice and that adoptive transfer of anti-HBV CD8(+) T cells restored the ability to clear HBV in HBV-carrier Rag1(-/-) mice. These results indicate that CD8(+) T cells are critical in HBV elimination. Furthermore, NK cells increased IFN-γ production after HBV plasmid injection, and NK cell depletion led to significantly increased HBV persistence along with reduced frequency of hepatitis B core Ag-specific CD8(+) T cells. Adoptive transfer of IFN-γ-sufficient NK cells restored donor CD8(+) T cell function, indicating that NK cells positively regulated CD8(+) T cells via secreting IFN-γ. We also observed that NK cell depletion correlated with decreased effector memory CD8(+) T cell frequencies. Importantly, adoptive transfer experiments showed that NK cells were involved in anti-HBV CD8(+) T cell recall responses. Moreover, DX5(+)CD49a(-) conventional, but not DX5(-)CD49a(+) liver-resident, NK cells were involved in improving CD8(+) T cell responses against HBV. Overall, the current study reveals that NK cells, especially DX5(+)CD49a(-) conventional NK cells, promote the antiviral activity of CD8(+) T cell responses via secreting IFN-γ in a mouse model mimicking acute HBV infection. PMID:27183639

  19. Synthesis and Crystal Structures of Hg 6Sb 5Br 7, Hg 6As 4BiCl 7, and Hg 6Sb 4BiBr 7, Built of a Polycationic Mercury-Pnictide Framework with Trapped Anions

    NASA Astrophysics Data System (ADS)

    Beck, Johannes; Hedderich, Sylvia; Neisel, Udo

    2000-11-01

    Hg6Sb5Br7, Hg6As4BiCl7, and Hg6Sb4BiBr7 were prepared from stoichiometric mixtures of Hg2X2, HgX2 (X=Cl, Br), As, Sb, and Bi in sealed, evacuated glass ampoules in temperature gradients 260→240°C for Hg6Sb5Br7, 340→320°C for Hg6As4BiCl7, and 290→270°C for Hg6Sb4BiBr7. All compounds crystallize in the cubic space group Paoverline3 with Z=4 and the lattice constants a=13.003(1) Å for Hg6Sb5Br7, a=12.178(2) Å for Hg6As4BiCl7, and a=12.998(4) Å for Hg6Sb4BiBr7. The structures have been solved based on single-crystal X-ray diffraction data and refined to R(F)=0.0431, 666 Fo for Hg6Sb5Br7, R(F)=0.0478, 690 Fo for Hg6As4BiCl7, and R(F)=0.0444, 840 Fo for Hg6Sb4BiBr7 with 30 parameters for each refinement. The structures are characterized by a three-dimensional polycationic framework of pnictide dumb-bells (As-As distance 2.43 Å, Sb-Sb distance 2.78 Å), each connected by six mercury atoms to six neighbored As2/Sb2 groups. There are two different cages in the framework; one type is occupied by nearly regular MX6 octahedra (M=Sb,Bi; X=Cl, Br), the other by halide ions. The three compounds crystallize closely related to Cd7P4Cl6, which contains a similar polycationic framework of P2 dumb-bells connected by Cd, but with only one type of cage occupied by octahedral [CdCl6]4- ions. The interactions between the atoms of the polycationic framework and the anions are very weak. The observed diamagnetism of all three compounds is in agreement with the ionic formulas (Hg6Sb4)4+[SbBr6]3-Br-, (Hg6As4)4+[BiCl6]3-Cl-, and (Hg6Sb4)4+[BiBr6]3-Br-.

  20. CD36 is a co-receptor for hepatitis C virus E1 protein attachment

    PubMed Central

    Cheng, Jun-Jun; Li, Jian-Rui; Huang, Meng-Hao; Ma, Lin-Lin; Wu, Zhou-Yi; Jiang, Chen-Chen; Li, Wen-Jing; Li, Yu-Huan; Han, Yan-Xing; Li, Hu; Chen, Jin-Hua; Wang, Yan-Xiang; Song, Dan-Qing; Peng, Zong-Gen; Jiang, Jian-Dong

    2016-01-01

    The cluster of differentiation 36 (CD36) is a membrane protein related to lipid metabolism. We show that HCV infection in vitro increased CD36 expression in either surface or soluble form. HCV attachment was facilitated through a direct interaction between CD36 and HCV E1 protein, causing enhanced entry and replication. The HCV co-receptor effect of CD36 was independent of that of SR-BI. CD36 monoclonal antibodies neutralized the effect of CD36 and reduced HCV replication. CD36 inhibitor sulfo-N-succinimidyl oleate (SSO), which directly bound CD36 but not SR-BI, significantly interrupted HCV entry, and therefore inhibited HCV replication. SSO’s antiviral effect was seen only in HCV but not in other viruses. SSO in combination with known anti-HCV drugs showed additional inhibition against HCV. SSO was considerably safe in mice. Conclusively, CD36 interacts with HCV E1 and might be a co-receptor specific for HCV entry; thus, CD36 could be a potential drug target against HCV. PMID:26898231

  1. The III-Bi binary compounds

    NASA Astrophysics Data System (ADS)

    Keen, Benjamin

    Bismuth containing III-V alloys such as GaAsBi, GaSbBi, InSbBi and InAsBi have recently become of great interest in the development of optical devices in the infrared spectrum. Difficulties in fabricating these materials stems, in part, from the lack of experimental data on the characteristics of the III-Bi family of compounds: AlBi, GaBi, and InBi. This thesis outlines the growth conditions and characteristics of the MBE deposition of InBi. To date, InBi remains the only one of the three compounds that has been experimentally reported, and the difficulties associated with the growth of AlBi and GaBi are also described herein. InBi thin films were grown on GaAs substrates at temperatures ranging from 50 °C to 100 °C. Unlike other III-V materials, which require a group V overpressure during deposition, to achieve stoichiometric quantities of indium and bismuth an In:Bi BEP ratio of 4:3 was found to be necessary. InBi samples were studied by a variety of measurement techniques, including SEM, EDX, XRD, HAXPES, and HRTEM. Films were found to grow in a 3-D Volmer-Weber mode, forming hemispherical droplets on the substrate surface. These droplets indicated clear signs of Ostwald ripening during growth, but maintained their distribution after deposition. InBi samples are believed to be semi-metallic, confirming some of the properties predicted by density functional theory (DFT) calculations. However, analysis of the crystal structure at the substrate/droplet interface indicates the epitaxial growth of InBi is in the zinc-blende configuration, instead of the PbO configuration, in direct opposition to predictions by DFT and experimental data reported from bulk crystal studies. Attempts to grow the other III-Bi materials, GaBi and AlBi, by MBE also resulted in 3-D droplet formation, but both gallium and aluminum failed to incorporate with bismuth to form a compound. Instead, the materials formed segregated regions in the droplets, clearly visible to SEM and EDX

  2. Collaborative interactions between type 2 innate lymphoid cells and antigen-specific CD4+ Th2 cells exacerbate murine allergic airway diseases with prominent eosinophilia.

    PubMed

    Liu, Bo; Lee, Jee-Boong; Chen, Chun-Yu; Hershey, Gurjit K Khurana; Wang, Yui-Hsi

    2015-04-15

    Type-2 innate lymphoid cells (ILC2s) and the acquired CD4(+) Th2 and Th17 cells contribute to the pathogenesis of experimental asthma; however, their roles in Ag-driven exacerbation of chronic murine allergic airway diseases remain elusive. In this study, we report that repeated intranasal rechallenges with only OVA Ag were sufficient to trigger airway hyperresponsiveness, prominent eosinophilic inflammation, and significantly increased serum OVA-specific IgG1 and IgE in rested mice that previously developed murine allergic airway diseases. The recall response to repeated OVA inoculation preferentially triggered a further increase of lung OVA-specific CD4(+) Th2 cells, whereas CD4(+) Th17 and ILC2 cell numbers remained constant. Furthermore, the acquired CD4(+) Th17 cells in Stat6(-/-)/IL-17-GFP mice, or innate ILC2s in CD4(+) T cell-ablated mice, failed to mount an allergic recall response to OVA Ag. After repeated OVA rechallenge or CD4(+) T cell ablation, the increase or loss of CD4(+) Th2 cells resulted in an enhanced or reduced IL-13 production by lung ILC2s in response to IL-25 and IL-33 stimulation, respectively. In return, ILC2s enhanced Ag-mediated proliferation of cocultured CD4(+) Th2 cells and their cytokine production, and promoted eosinophilic airway inflammation and goblet cell hyperplasia driven by adoptively transferred Ag-specific CD4(+) Th2 cells. Thus, these results suggest that an allergic recall response to recurring Ag exposures preferentially triggers an increase of Ag-specific CD4(+) Th2 cells, which facilitates the collaborative interactions between acquired CD4(+) Th2 cells and innate ILC2s to drive the exacerbation of a murine allergic airway diseases with an eosinophilic phenotype. PMID:25780046

  3. Developing a biocuration workflow for AgBase, a non-model organism database

    PubMed Central

    Pillai, Lakshmi; Chouvarine, Philippe; Tudor, Catalina O.; Schmidt, Carl J.; Vijay-Shanker, K.; McCarthy, Fiona M.

    2012-01-01

    AgBase provides annotation for agricultural gene products using the Gene Ontology (GO) and Plant Ontology, as appropriate. Unlike model organism species, agricultural species have a body of literature that does not just focus on gene function; to improve efficiency, we use text mining to identify literature for curation. The first component of our annotation interface is the gene prioritization interface that ranks gene products for annotation. Biocurators select the top-ranked gene and mark annotation for these genes as ‘in progress’ or ‘completed’; links enable biocurators to move directly to our biocuration interface (BI). Our BI includes all current GO annotation for gene products and is the main interface to add/modify AgBase curation data. The BI also displays Extracting Genic Information from Text (eGIFT) results for each gene product. eGIFT is a web-based, text-mining tool that associates ranked, informative terms (iTerms) and the articles and sentences containing them, with genes. Moreover, iTerms are linked to GO terms, where they match either a GO term name or a synonym. This enables AgBase biocurators to rapidly identify literature for further curation based on possible GO terms. Because most agricultural species do not have standardized literature, eGIFT searches all gene names and synonyms to associate articles with genes. As many of the gene names can be ambiguous, eGIFT applies a disambiguation step to remove matches that do not correspond to this gene, and filtering is applied to remove abstracts that mention a gene in passing. The BI is linked to our Journal Database (JDB) where corresponding journal citations are stored. Just as importantly, biocurators also add to the JDB citations that have no GO annotation. The AgBase BI also supports bulk annotation upload to facilitate our Inferred from electronic annotation of agricultural gene products. All annotations must pass standard GO Consortium quality checking before release in Ag

  4. Investigation on the interaction of nanoAg with Cu-Zn SOD.

    PubMed

    Zhang, Bin; Yu, Lei; Zhang, Ruijing; Liu, Yang; Liu, Rutao

    2015-12-01

    Silver nanoparticles (nanoAg) are used more and more widely, particularly because of their antimicrobial properties. The effect of exposure to nanoAg on the structure of superoxide dismutase (SOD) was thoroughly investigated using fluorescence measurements, synchronous fluorescence spectroscopy, steady-state and time-resolved fluorescence quenching measurements, UV/Vis absorption spectroscopy, resonance light scattering (RLS), circular dichroism (CD), isothermal titration calorimetry (ITC) and high-resolution transmission electron microscopy (HRTEM). Through van der Waal's force, nanoAg interacted with Cu-Zn SOD and influenced the active site by inducing structural changes, which influenced the function of SOD. The fluorescence studies show that both static and dynamic quenching processes occur. This paper provides reference data for toxicological studies of nanoAg, which are important in the future development of nanotechnology. PMID:25754791

  5. An overwhelmingly selective colorimetric sensor for Ag(+) using a simple modified polyacrylonitrile fiber.

    PubMed

    Xing, Xiaoli; Yang, Huixiao; Tao, Minli; Zhang, Wenqin

    2015-10-30

    A carboxymethyl-dithiocarbamate immobilized polyacrylonitrile fiber colorimetric sensor has been synthesized. This fiber sensor exhibits excellent selectivity and sensitivity for Ag(+) in aqueous solution with a remarkable color change from light pink to red-brown over a wide pH range of 2-12. The sensor responds selectively to Ag(+) in the presence of other ions, including Mg(2+), Al(3+), Ca(2+), Cr(3+), Mn(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+). The colorimetric sensor has an extremely fast response time (10s) and a low visual limit of detection (5.53×10(-12) mol/L). The fiber sensor also undergoes an obvious color change in the presence of Ag(+) solutions containing EDTA, NaCl or NaBr. Density functional theory optimization reveals that the sensor and Ag(+) interact via a seven-membered ring complexation mechanism. PMID:25967097

  6. A novel rosamine based fluorescent sensor for Ag+ recognition

    NASA Astrophysics Data System (ADS)

    Li, Lian-Qing; Gao, Le-Jun

    2016-01-01

    Rosamine derivative, N-(9-(4-(bis(2-(ethylthio)ethyl)amino)phenyl)-6-(diethylamino)-3H-xanthen-3-ylidene)-N-ethylethanaminium hexafluorophosphate, L, bearing an NS2 group as receptor, was synthesized as a turn on chemosensor for silver ion in ethanol solution. Sensor L exhibited high selectivity toward Ag+ in comparison to other metal cations (Cd2+, Cu2+, Hg2+, Na+, Mg2+, Ni2+, Pb2+, Fe3+, and Zn2+). The detection limit for Ag+ was in 10-7 level. The binding properties between silver ion and L were further studied by 1HNMR titration experiments. The chemosensor L can be used as a potential material for silver recognition.

  7. Bonding of a silver sheath on textured-powder ribbons of green-state Bi-2212 superconductor

    NASA Astrophysics Data System (ADS)

    Smit, Klaus; McIntyre, Peter; Damborsky, Kyle; Lu, Feng; Pogue, Nathaniel

    2011-10-01

    A novel method is being developed for fabrication of textured-powder jelly-roll (TPJR) Bi-2212/Ag superconducting wire for applications in high-field magnets. In this process two silver foils must be fused together to enclose a ribbon of compacted, textured Bi-2212 fine powder. Fusing the silver foils must be accomplished with minimum heating of the superconducting powder filling. We are investigating methods using cold-welding, ultrasonic welding, and laser welding. Results of those investigations will be reported.

  8. Spin dynamics simulations at AGS

    SciTech Connect

    Huang, H.; MacKay, W.W.; Meot, F.; Roser, T.

    2010-05-23

    To preserve proton polarization through acceleration, it is important to have a correct model of the process. It has been known that with the insertion of the two helical partial Siberian snakes in the Alternating Gradient Synchrotron (AGS), the MAD model of AGS can not deal with a field map with offset orbit. The stepwise ray-tracing code Zgoubi provides a tool to represent the real electromagnetic fields in the modeling of the optics and spin dynamics for the AGS. Numerical experiments of resonance crossing, including spin dynamics in presence of the snakes and Q-jump, have been performed in AGS lattice models, using Zgoubi. This contribution reports on various results so obtained.

  9. 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.

  10. Mannose-Capped Lipoarabinomannan from Mycobacterium tuberculosis Induces CD4+ T Cell Anergy via GRAIL.

    PubMed

    Sande, Obondo J; Karim, Ahmad F; Li, Qing; Ding, Xuedong; Harding, Clifford V; Rojas, Roxana E; Boom, W Henry

    2016-01-15

    Mycobacterium tuberculosis cell wall glycolipid, lipoarabinomannan, can inhibit CD4(+) T cell activation by downregulating the phosphorylation of key proximal TCR signaling molecules: Lck, CD3ζ, ZAP70, and LAT. Inhibition of proximal TCR signaling can result in T cell anergy, in which T cells are inactivated following an Ag encounter, yet remain viable and hyporesponsive. We tested whether mannose-capped lipoarabinomannan (LAM)-induced inhibition of CD4(+) T cell activation resulted in CD4(+) T cell anergy. The presence of LAM during primary stimulation of P25 TCR-transgenic murine CD4(+) T cells with M. tuberculosis Ag85B peptide resulted in decreased proliferation and IL-2 production. P25 TCR-transgenic CD4(+) T cells primed in the presence of LAM also exhibited decreased response upon restimulation with Ag85B. The T cell anergic state persisted after the removal of LAM. Hyporesponsiveness to restimulation was not due to apoptosis, generation of Foxp3-positive regulatory T cells, or inhibitory cytokines. Acquisition of the anergic phenotype correlated with upregulation of gene related to anergy in lymphocytes (GRAIL) protein in CD4(+) T cells. Inhibition of human CD4(+) T cell activation by LAM also was associated with increased GRAIL expression. Small interfering RNA-mediated knockdown of GRAIL before LAM treatment abrogated LAM-induced hyporesponsiveness. In addition, exogenous IL-2 reversed defective proliferation by downregulating GRAIL expression. These results demonstrate that LAM upregulates GRAIL to induce anergy in Ag-reactive CD4(+) T cells. Induction of CD4(+) T cell anergy by LAM may represent one mechanism by which M. tuberculosis evades T cell recognition. PMID:26667170

  11. A Brucella spp. Protease Inhibitor Limits Antigen Lysosomal Proteolysis, Increases Cross-Presentation, and Enhances CD8+ T Cell Responses.

    PubMed

    Coria, Lorena M; Ibañez, Andrés E; Tkach, Mercedes; Sabbione, Florencia; Bruno, Laura; Carabajal, Marianela V; Berguer, Paula M; Barrionuevo, Paula; Schillaci, Roxana; Trevani, Analía S; Giambartolomei, Guillermo H; Pasquevich, Karina A; Cassataro, Juliana

    2016-05-15

    In this study, we demonstrate that the unlipidated (U) outer membrane protein (Omp) 19 from Brucella spp. is a competitive inhibitor of human cathepsin L. U-Omp19 inhibits lysosome cathepsins and APC-derived microsome activity in vitro and partially inhibits lysosomal cathepsin L activity within live APCs. Codelivery of U-Omp19 with the Ag can reduce intracellular Ag digestion and increases Ag half-life in dendritic cells (DCs). U-Omp19 retains the Ag in Lamp-2(+) compartments after its internalization and promotes a sustained expression of MHC class I/peptide complexes in the cell surface of DCs. Consequently, U-Omp19 enhances Ag cross-presentation by DCs to CD8(+) T cells. U-Omp19 s.c. delivery induces the recruitment of CD11c(+)CD8α(+) DCs and monocytes to lymph nodes whereas it partially limits in vivo Ag proteolysis inside DCs. Accordingly, this protein is able to induce CD8(+) T cell responses in vivo against codelivered Ag. Antitumor responses were elicited after U-Omp19 coadministration, increasing survival of mice in a murine melanoma challenge model. Collectively, these results indicate that a cysteine protease inhibitor from bacterial origin could be a suitable component of vaccine formulations against tumors. PMID:27084100

  12. Systemic immunological tolerance to ocular antigens is mediated by TNF-related apoptosis-inducing ligand (TRAIL)-expressing CD8+ T cells*

    PubMed Central

    Griffith, Thomas S.; Brincks, Erik L.; Gurung, Prajwal; Kucaba, Tamara A.; Ferguson, Thomas A.

    2010-01-01

    Systemic immunological tolerance to Ag encountered in the eye restricts the formation of potentially damaging immune responses that would otherwise be initiated at other anatomical locations. We previously demonstrated that tolerance to Ag administered via the anterior chamber (AC) of the eye required FasL-mediated apoptotic death of inflammatory cells that enter the eye in response to the antigenic challenge. Moreover, the systemic tolerance induced after AC injection of Ag was mediated by CD8+ regulatory T cells. The present study examined the mechanism by which these CD8+ regulatory T cells mediate tolerance after AC injection of Ag. AC injection of Ag did not prime CD4+ T cells, and led to increased TRAIL expression by splenic CD8+ T cells. Unlike wildtype mice, Trail−/− or Dr5−/− mice did not develop tolerance to Ag injected into the eye, even though responding lymphocytes underwent apoptosis in the AC of the eyes of these mice. CD8+ T cells from Trail−/− mice that were first injected AC with Ag were unable to transfer tolerance to naïve recipient wildtype mice, but CD8+ T cells from AC-injected wildtype or Dr5−/− mice could transfer tolerance. Importantly, the transferred wildtype (Trail+/+) CD8+ T cells were also able to decrease the number of infiltrating inflammatory cells into the eye; however, Trail−/− CD8+ T cells were unable to limit the inflammatory cell ingress. Together, our data suggest that “helpless” CD8+ regulatory T cells generated after AC injection of Ag enforce systemic tolerance in a TRAIL-dependent manner to inhibit inflammation in the eye. PMID:21169546

  13. CD103+ dendritic cells suppress Helminth-driven Type 2 immunity through constitutive expression of IL-12

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Batf3-dependent CD103+ and CD8alpha+ dendritic cells (DCs) play a central role in the development of type 1 immune responses. However, their role in type 2 immunity remains unclear. We found that Th2 cell responses were enhanced in Batf3-/- mice responding to helminth parasite antigens (Ag). As a r...

  14. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate

    NASA Astrophysics Data System (ADS)

    Jun Yin, Hong; Yang Chen, Zhao; Mei Zhao, Yong; Yang Lv, Ming; An Shi, Chun; Long Wu, Zheng; Zhang, Xin; Liu, Luo; Li Wang, Ming; Jun Xu, Hai

    2015-09-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br- and I-), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd2+ at 10-8  M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface.

  15. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate.

    PubMed

    Yin, Hong Jun; Chen, Zhao Yang; Zhao, Yong Mei; Lv, Ming Yang; Shi, Chun An; Wu, Zheng Long; Zhang, Xin; Liu, Luo; Wang, Ming Li; Xu, Hai Jun

    2015-01-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br(-) and I(-)), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd(2+) at 10(-8) M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface. PMID:26412773

  16. Ag@Au core-shell dendrites: a stable, reusable and sensitive surface enhanced Raman scattering substrate

    PubMed Central

    Jun Yin, Hong; Yang Chen, Zhao; Mei Zhao, Yong; Yang Lv, Ming; An Shi, Chun; Long Wu, Zheng; Zhang, Xin; Liu, Luo; Li Wang, Ming; Jun Xu, Hai

    2015-01-01

    Surface enhanced Raman scattering (SERS) substrate based on fabricated Ag@Au core-shell dendrite was achieved. Ag dendrites were grown on Si wafer by the hydrothermal corrosion method and Au nanofilm on the surface of Ag dendritic nanostructure was then fabricated by chemical reduction. With the help of sodium borohydride in water, Au surface absorbates such as thiophene, adenine, rhodamine, small anions (Br– and I–), and a polymer (PVP, poly(N-vinylpyrrolidone)) can be completely and rapidly removed. After four repeatable experiments, the substrate SERS function did not decrease at all, indicating that the Ag@Au dendrite should be of great significance to SERS application because it can save much resource. Six-month-duration stability tests showed that the Ag@Au core-shell dendrite substrate is much more stable than the Ag dendrite substrates. We have also experimented on fast detection of Cd2+ at 10−8  M concentration by decorating single-stranded DNA containing adenine and guanine bases on the surface of this Ag@Au dendrite. Finite-difference time-domain simulations were carried out to investigate the influence of Au nanolayer on Ag dendrites, which showed that the local electric fields and enhancement factor are hardly affected when a 4 nm Au nanolayer is coated on Ag dendrite surface. PMID:26412773

  17. 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.

  18. CD8+ CD28− and CD8+ CD57+ T cells and their role in health and disease

    PubMed Central

    Strioga, Marius; Pasukoniene, Vita; Characiejus, Dainius

    2011-01-01

    Chronic antigenic stimulation leads to gradual accumulation of late-differentiated, antigen-specific, oligoclonal T cells, particularly within the CD8+ T-cell compartment. They are characterized by critically shortened telomeres, loss of CD28 and/or gain of CD57 expression and are defined as either CD8+CD28− or CD8+CD57+ T lymphocytes. There is growing evidence that the CD8+CD28− (CD8+CD57+) T-cell population plays a significant role in various diseases or conditions, associated with chronic immune activation such as cancer, chronic intracellular infections, chronic alcoholism, some chronic pulmonary diseases, autoimmune diseases, allogeneic transplantation, as well as has a great influence on age-related changes in the immune system status. CD8+CD28− (CD8+CD57+) T-cell population is heterogeneous and composed of various functionally competing (cytotoxic and immunosuppressive) subsets thus the overall effect of CD8+CD28− (CD8+CD57+) T-cell-mediated immunity depends on the predominance of a particular subset. Many articles claim that CD8+CD28− (CD8+CD57+) T cells have lost their proliferative capacity during process of replicative senescence triggered by repeated antigenic stimulation. However recent data indicate that CD8+CD28− (CD8+CD57+) T cells can transiently up-regulate telomerase activity and proliferate under certain stimulation conditions. Similarly, conflicting data is provided regarding CD8+CD28− (CD8+CD57+) T-cell sensitivity to apoptosis, finally leading to the conclusion that this T-cell population is also heterogeneous in terms of its apoptotic potential. This review provides a comprehensive approach to the CD8+CD28− (CD8+CD57+) T-cell population: we describe in detail its origins, molecular and functional characteristics, subsets, role in various diseases or conditions, associated with persistent antigenic stimulation. PMID:21711350

  19. Targeting with bovine CD154 enhances humoral immune responses induced by a DNA vaccine in sheep.

    PubMed

    Manoj, Sharmila; Griebel, Philip J; Babiuk, Lorne A; van Drunen Littel-van den Hurk, Sylvia

    2003-01-15

    CD40-CD154 interactions play an important role in regulating humoral and cell-mediated immune responses. Recently, these interactions have been exploited for the development of therapeutic and preventive treatments. The objective of this study was to test the ability of bovine CD154 to target a plasmid-encoded Ag to CD40-expressing APCs. To achieve this, a plasmid coding for bovine CD154 fused to a truncated secreted form of bovine herpesvirus 1 glycoprotein D (tgD), pSLIAtgD-CD154, was constructed. The chimeric tgD-CD154 was expressed in vitro in COS-7 cells and reacted with both glycoprotein D- and CD154-specific Abs. Both tgD and tgD-CD154 were capable of binding to epithelial cells, whereas only tgD-CD154 bound to B cells. Furthermore, dual-labeling of ovine PBMCs revealed that tgD-CD154 was bound by primarily B cells. The functional integrity of the tgD-CD154 chimera was confirmed by the induction of both IL-4-dependent B cell proliferation and tgD-specific lymphoproliferative responses in vitro. Finally, sheep immunized with pSLIAtgD-CD154 developed a more rapid primary tgD-specific Ab response and a significantly stronger tgD-specific secondary response when compared with animals immunized with pSLIAtgD and control animals. Similarly, virus-neutralizing Ab titers were significantly higher after secondary immunization with pSLIAtgD-CD154. These results demonstrate that using CD154 to target plasmid-expressed Ag can significantly enhance immune responses induced by a DNA vaccine. PMID:12517965

  20. Bonding of Bi2Te3-Based Thermoelectric Legs to Metallic Contacts Using Bi0.82Sb0.18 Alloy

    NASA Astrophysics Data System (ADS)

    Vizel, Roi; Bargig, Tal; Beeri, Ofer; Gelbstein, Yaniv

    2016-03-01

    Thermoelectrics is gaining increased attention as a renewable direct energy conversion method from heat to electricity. The most efficient and up-to-date thermoelectric materials for temperatures of up to 250°C are (Bi1- x Sb x )2 (Te1- y Se y )3 alloys. In the current research, to discover practical thermoelectric power generation devices capable of operation at such temperatures, Bi0.82Sb0.18 alloy was considered as a lead-free high-temperature (<250°C) solder composition for bonding of n-type Bi2Te2.4Se0.6 and p-type Bi0.4Sb1.6Te3 legs into Cu, Ag, Ni and Fe metallic bridges. In the case of Cu, fine contacts with low electrical contact resistance of ˜1.5 ± 0.5 mΩ mm2 were observed upon soldering at 350°C.

  1. 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

  2. Bi-stable optical actuator

    DOEpatents

    Holdener, Fred R.; Boyd, Robert D.

    2000-01-01

    The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

  3. 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.

  4. Time-Tested ERIC Bibliographic Instruction (BI): Give Them a Pole and Teach Them To Fish (Fiche).

    ERIC Educational Resources Information Center

    Leverence, Mari Ellen

    This article outlines an Educational Resources Information Center (ERIC) CD-ROM bibliographic instruction (BI) session at an academic library, which is intended to produce knowledgeable and competent ERIC searchers. The 1.5 hour lecture session includes: a basic introduction to the ERIC database; narrowing down a search topic; using the thesaurus…

  5. Temperature-dependent thermal expansion of cast and hot-pressed LAST (Pb-Sb-Ag-Te) thermoelectric materials

    SciTech Connect

    Ren, Fei; Hall, Bradley D.; Case, Eldon D; Timm, Edward J; Trejo, Rosa M; Meisner, Roberta Ann; Lara-Curzio, Edgar

    2009-01-01

    The thermal expansion for two compositions of cast and hot-pressed LAST (Pb Sb Ag Te) n-type thermoelectric materials has been measured between room temperature and 673K via thermomechanical analysis (TMA). In addition, using high-temperature X-ray diffraction (HT-XRD), the thermal expansion for both cast and hot-pressed LAST materials was determined from the temperature-dependent lattice parameters measured between room temperature and 623 K. The TMA and HT-XRD determined values of the coefficient of thermal expansion (CTE) for the LAST compositions ranged between 20106K1 and 24106K1, which is comparable to the CTE values for other thermoelectric materials including PbTe and Bi2Te3. The CTE of the LAST specimens with a higher Ag content (Ag0.86Pb19Sb1.0Te20) exhibited a higher CTE value than that of the LAST material with a lower Ag content (Ag0.43Pb18Sb1.2Te20). In addition, a peak in the temperature-dependent CTE was observed between room temperature and approximately 450K for both the cast and hot-pressed LAST with the Ag0.86Pb19Sb1.0Te20 composition, whereas the CTE of the Ag0.43Pb18Sb1.2Te20 specimen increased monotonically with temperature.

  6. Fabrication of Bi-(Pb)-Sr-Ca-Cu-O mono- and multifilamentary superconductors and improvement in critical current density

    NASA Astrophysics Data System (ADS)

    Sekine, H.; Inoue, K.; Maeda, H.; Numata, K.

    1989-09-01

    This paper describes procedures for the fabrication of the Bi-(Pb)-Sr-Ca-Cu-O superconducting material as tapes without sheathing and as multifilamentary wires and tapes with Ag sheathing, together with results from metallurgical studies and measurements of superconducting properties. Tape specimens of 0.5-1.0-mm thickness, prepared by combination and repetition of cold work and sintering, showed critical current density Jc as high as 5000 A/sq cm at 77 K, with good reproducibility and reliability. A 1330-filament Bi-Pb-Sr-Ca-Cu-O wire with an Ag sheath showed critical temperature of about 105 K, and a multifilamentary tape specimen showed Jc of 1050 A/sq cm at 77 K. The process of repetition of cold work and sintering had the effect of Jc enhancement on multifilamentary tapes.

  7. CdTe and ZnTe metal interface formation and Fermi-level pinning

    NASA Technical Reports Server (NTRS)

    Wahi, A. K.; Carey, G. P.; Chiang, T. T.; Lindau, I.; Spicer, W. E.

    1989-01-01

    Interfacial morphology and Fermi-level pinning behavior at the interfaces of Al, Ag, and Pt with UHV-cleaved CdTe and ZnTe are studied using X-ray photoelectron and ultraviolet photoemission spectroscopies. Results are compared to metal/HgCdTe interface formation. For Al/CdTe, a case is found where significantly greater intermixing occurs in CdTe than seen on HgCdTe. The Al/ZnTe interface is also more abrupt than Al/CdTe. Band bending results for interfaces of all three metals with p-CdTe and p-ZnTe are presented and implications for metal/HgZnTe interface formation are considered.