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Sample records for ags main magnet

  1. Control and performance of the AGS and AGS Booster Main Magnet Power Supplies

    SciTech Connect

    Reece, R.K.; Casella, R.; Culwick, B.; Geller, J.; Marneris, I.; Sandberg, J.; Soukas, A.; Zhang, S.Y.

    1993-01-01

    Techniques for precision control of the main magnet power supplies for the AGS and AGS Booster synchrotron will be discussed. Both synchrotrons are designed to operate in a Pulse-to-Pulse Modulation (PPM) environment with a Supercycle Generator defining and distributing global timing events for the AGS Facility. Details of modelling, real-time feedback and feedforward systems, generation and distribution of real time field data, operational parameters and an overview of performance for both machines are included.

  2. Control and performance of the AGS and AGS Booster Main Magnet Power Supplies

    SciTech Connect

    Reece, R.K.; Casella, R.; Culwick, B.; Geller, J.; Marneris, I.; Sandberg, J.; Soukas, A.; Zhang, S.Y.

    1993-06-01

    Techniques for precision control of the main magnet power supplies for the AGS and AGS Booster synchrotron will be discussed. Both synchrotrons are designed to operate in a Pulse-to-Pulse Modulation (PPM) environment with a Supercycle Generator defining and distributing global timing events for the AGS Facility. Details of modelling, real-time feedback and feedforward systems, generation and distribution of real time field data, operational parameters and an overview of performance for both machines are included.

  3. The AGS synchrotron with four helical magnets

    SciTech Connect

    Tsoupas N.; Huang, H.; Roser, T.; MacKay, W.W.; Trbojevic, D.

    2012-05-20

    The idea of using two partial helical magnets was applied successfully to the AGS synchrotron to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. The placement of four helical magnets in the AGS ring provides many advantages over the present setup of the AGS which uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides for a larger 'spin tune gap', which allows the vertical and horizontal tunes to be placed, and prevent the horizontal and vertical intrinsic spin resonances of the AGS to occur during the acceleration cycle. Although the same spin gap can be obtained with a single or two partial helices, the required high field strength of a single helix makes its use impractical, and that of the double helix rather difficult. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and compare these results with the present setup of the AGS that uses two partial helical magnets.

  4. The AGS with four helical magnets

    SciTech Connect

    Tsoupas, N.; Huang, H.; MacKay, W.W.; Roser, T.; Trbojevic, D.

    2010-02-25

    The idea of using multiple partial helical magnets was applied successfully to the AGS synchrotron, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, it provides a larger 'spin tune gap' for the placement of the vertical betatron tune of the AGS during acceleration, second, the vertical spin direction during the beam injection and extraction is closer to vertical, third, the symmetric placement of the snakes allows for a better control of the AGS optics, and for reduced values of the beta and eta functions, especially near injection, fourth, the optical properties of the helical magnets also favor the placement of the horizontal betatron tune in the 'spin tune gap', thus eliminating the horizontal spin resonances. In this paper we provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and we compare these results with the present setup of the AGS that uses two partial helical magnets.

  5. Topology of Saturn's main magnetic field

    NASA Astrophysics Data System (ADS)

    Acuna, M. H.; Connerney, J. E. P.; Ness, N. F.

    1981-08-01

    The reported analysis of Saturn's main magnetic field takes into account the data obtained by Voyager 1 during its close flyby of Saturn in November 1980. A magnetic field model for the analysis of Saturn's main field in which the distributed ring currents are explicitly modelled is constructed. The considered internal field parameters constitute a first approximation to Saturn's main field. Several model current systems that might be expected on physical grounds to be active in Saturn's magnetosphere are considered. It is pointed out that certain aspects of Saturn's main magnetic field relevant to the planet's interior have been discussed by Stevenson (1980). In particular, the unexpectedly small dipole moment seems to be consistent with the gravitational settling of helium, which leads to a much smaller electrically conducting and convecting region than would be expected of a homogeneous distribution of hydrogen and helium.

  6. The main magnetic field of Jupiter

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.; Ness, N. F.

    1976-01-01

    The main magnetic field of Jupiter has been measured by the Goddard Space Flight Center flux gate magnetometer on Pioneer 11. Analysis of the data yields a more detailed model than that obtained from Pioneer 10 results. In a spherical harmonic octupole representation the dipole term (with opposite polarity to earth's) has a magnitude of 4.28 G times the radial distance cubed at a tilt angle of 9.6 deg and a system 111 longitude of 232 deg. The quadrupole and octupole moments are 24% and 21% of the dipole, respectively. This leads to a significant deviation of the planetary magnetic field from a simple offset dipole topology at distances of less than three times the radial distance. The north polar field strength is 14 G, and in the Northern Hemisphere the 'footprint' of the Io associated flux tube traverses the magnetic polar region. Associated L shell splitting in the radiation belts, warping of the charged particle equatorial planes, and enhanced absorption effects due to the satellites Amalthea and Io are expected as a result of the field complexity.

  7. Ag/FeCo/Ag core/shell/shell magnetic nanoparticles with plasmonic imaging capability.

    PubMed

    Takahashi, Mari; Mohan, Priyank; Nakade, Akiko; Higashimine, Koichi; Mott, Derrick; Hamada, Tsutomu; Matsumura, Kazuaki; Taguchi, Tomohiko; Maenosono, Shinya

    2015-02-24

    Magnetic nanoparticles (NPs) have been used to separate various species such as bacteria, cells, and proteins. In this study, we synthesized Ag/FeCo/Ag core/shell/shell NPs designed for magnetic separation of subcellular components like intracellular vesicles. A benefit of these NPs is that their silver metal content allows plasmon scattering to be used as a tool to observe detection by the NPs easily and semipermanently. Therefore, these NPs are considered a potential alternative to existing fluorescent probes like dye molecules and colloidal quantum dots. In addition, the Ag core inside the NPs suppresses the oxidation of FeCo because of electron transfer from the Ag core to the FeCo shell, even though FeCo is typically susceptible to oxidation. The surfaces of the Ag/FeCo/Ag NPs were functionalized with ε-poly-L-lysine-based hydrophilic polymers to make them water-soluble and biocompatible. The imaging capability of the polymer-functionalized NPs induced by plasmon scattering from the Ag core was investigated. The response of the NPs to a magnetic field using liposomes as platforms and applying a magnetic field during observation by confocal laser scanning microscopy was assessed. The results of the magnetophoresis experiments of liposomes allowed us to calculate the magnetic force to which each liposome was subjected.

  8. Lifetime measurements and magnetic rotation in 107Ag

    NASA Astrophysics Data System (ADS)

    Yao, S. H.; Ma, H. L.; Zhu, L. H.; Wu, X. G.; He, C. Y.; Zheng, Y.; Zhang, B.; Li, G. S.; Li, C. B.; Hu, S. P.; Cao, X. P.; Yu, B. B.; Xu, C.; Cheng, Y. Y.

    2014-01-01

    The excited states in 107Ag were populated through the heavy-ion fusion evaporation reaction 100Mo (11B, 4n) 107Ag at a beam energy of 46 MeV. Lifetimes of high-spin states in 107Ag have been measured through the Doppler shift attenuation method. The deduced B (M1) values, gradually decreasing with increasing spin, clearly demonstrate that both the yrast positive-parity band and the yrast negative-parity band in 107Ag are magnetic rotation bands. Furthermore, experimental deduced B (M1) values for the yrast positive-parity band are compared with the predictions of the particle rotor model. The approximate agreement between theoretical calculations and experimental results further confirms the mechanism of magnetic rotation for the yrast positive-parity band. In addition, a systematic investigation shows the evolution of the magnetic rotation mechanism in the A ≈110 mass region.

  9. Active magnetic suspension in main magnetic field of electric motor

    NASA Astrophysics Data System (ADS)

    Urusov, I. D.; Galkin, V. I.; Likhoshvay, I. P.

    1985-10-01

    An active magnetic suspension for the rotor of an electric motor is considered, especially in small or miniature high-speed devices such as gyros, microturbomachines, and machine-tool spindle drives where it would eliminate the need for extra bearings and contribute to size and weight reduction. A disk-type rotor made of a ferromagnetic material is located horizontally inside the bore of a vertical stator so that weight and external loads compensate the magnetic pull upward. This pull is generated by the magnetic field in the air gap and can be automatically controlled by an electronic feedback circuit which regulates the stator input voltage depending on the rotor position along the stator bore, with a displacement transducer on the rotor indicating the position. The performance of such a suspension with automatic control in a 3-phase induction motor is analyzed on the basis of the system of differential equations describing the behavior of the electromechanical system during axial oscillations of the rotor, assuming a constant rotor speed during the transient periods.

  10. Magnetic main sequence stars as progenitors of blue supergiants

    NASA Astrophysics Data System (ADS)

    Petermann, I.; Castro, N.; Langer, N.

    2015-01-01

    Blue supergiants (BSGs) to the right the main sequence band in the HR diagram can not be reproduced by standard stellar evolution calculations. We investigate whether a reduced convective core mass due to strong internal magnetic fields during the main sequence might be able to recover this population of stars. We perform calculations with a reduced mass of the hydrogen burning convective core of stars in the mass range 3-30 M ⊙ in a parametric way, which indeed lead to BSGs. It is expected that these BSGs would still show large scale magnetic fields in the order of 10 G.

  11. BOOSTER MAIN MAGNET POWER SUPPLY IMPROVEMENTS FOR NASA SPACE RADIATION LABORATORY AT BNL

    SciTech Connect

    MARNERIS,I.BROWN,K.A.GLENN,J.W.MCNERNEY,A., MORRIS, J., SANDBERG,J., SAVATTERI, S.

    2003-05-12

    The NASA Space Radiation Laboratory (NSRL), constructed at Brookhaven National Laboratory, under contract from NASA, is a new experimental facility, taking advantage of heavy-ion beams from the Brookhaven Alternating Gradient Synchrotron (AGS) Booster accelerator, to study radiation effect on humans, for prolonged space missions beyond the protective terrestrial magnetosphere. This paper describes the modifications and operation of the Booster Main Magnet Power Supply (MMPS) for NSRL applications. The requirement is to run up to 1 sec flattops as high as 5000 Amps with 25% duly cycle. The controls for the Main Magnet Power Supply were modified, including the Booster Main Magnet application program, to enable flattop operation with low ripple and spill control. An active filter (AF) consisting of a {+-}120 volts, {+-}700 Amps power supply transformer coupled through a filter choke, in series with the Main Magnet voltage, was added to the system to enable further ripple reduction during the flattops. We will describe the spill servo system, designed to provide a uniform beam current, during the flattop. Results from system commissioning will be presented.

  12. Interfacial magnetic coupling between Fe nanoparticles in Fe–Ag granular alloys.

    PubMed

    Alonso, J; Fdez-Gubieda, M L; Sarmiento, G; Chaboy, J; Boada, R; García Prieto, A; Haskel, D; Laguna-Marco, M A; Lang, J C; Meneghini, C; Fernández Barquín, L; Neisius, T; Orue, I

    2012-01-20

    The role of the interface in mediating interparticle magnetic interactions has been analysed in Fe50Ag50 and Fe55Ag45 granular thin films deposited by the pulsed laser deposition technique (PLD). These samples are composed of crystalline bcc Fe (2–4 nm) nanoparticles and fcc Ag (10–12 nm) nanoparticles, separated by an amorphous Fe50Ag50 interface, occupying around 20% of the sample volume, as determined by x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and high resolution transmission electron microscopy (HRTEM). Interfacial magnetic coupling between Fe nanoparticles is studied by dc magnetization and x-ray magnetic circular dichroism (XMCD) measurements at the Fe K and Ag L2,3 edges. This paper reveals that these thin films present two magnetic transitions, at low and high temperatures, which are strongly related to the magnetic state of the amorphous interface, which acts as a barrier for interparticle magnetic coupling.

  13. Retraining of the 1232 Main Dipole Magnets in the LHC

    SciTech Connect

    Verweij, A.; Auchmann, B.; Bednarek, M.; Bottura, L.; Charifoulline, Z.; Feher, S.; Hagen, P.; Modena, M.; Le Naour, S.; Romera, I.; Siemko, A.; Steckert, J.; Tock, J. Ph; Todesco, E.; Willering, G.; Wollmann, D.

    2016-01-05

    The Large Hadron Collider (LHC) contains eight main dipole circuits, each of them with 154 dipole magnets powered in series. These 15-m-long magnets are wound from Nb-Ti superconducting Rutherford cables, and have active quench detection triggering heaters to quickly force the transition of the coil to the normal conducting state in case of a quench, and hence reduce the hot spot temperature. During the reception tests in 2002-2007, all these magnets have been trained up to at least 12 kA, corresponding to a beam energy of 7.1 TeV. After installation in the accelerator, the circuits have been operated at reduced currents of up to 6.8 kA, from 2010 to 2013, corresponding to a beam energy of 4 TeV. After the first long shutdown of 2013-2014, the LHC runs at 6.5 TeV, requiring a dipole magnet current of 11.0 kA. A significant number of training quenches were needed to bring the 1232 magnets up to this current. In this paper, the circuit behavior in case of a quench is presented, as well as the quench training as compared to the initial training during the reception tests of the individual magnets.

  14. Synthesis, structures, and luminescent and magnetic properties of Ln-Ag heterometal-organic frameworks.

    PubMed

    Zhao, Xiao-Qing; Zhao, Bin; Wei, Shi; Cheng, Peng

    2009-12-07

    A series of Ln-Ag heterometal-organic frameworks based on 4-hydroxylpyridine-2,6-dicarboxylic acid (H(3)CAM) with formulas {LaAg(2)(CAM)(HCAM)(H(2)O)(2)}(n) (1), {LnAg(HCAM)(2)(H(2)O)(3)}(n) (Ln = Pr, 2; Nd, 3; Sm, 4; Eu, 5), and {LnAg(3)(CAM)(2)(H(2)O)}(n) (Ln = Gd, 6; Tb, 7; Dy, 8; Tm, 9; Yb, 10), have been synthesized with the hydrothermal reaction of Ln(OH)(3), Ag(2)O, and H(3)CAM at 160 degrees C. The single-crystal X-ray diffraction analyses reveal that three kinds of structures are exclusively governed by the size of lanthanide ions and the progression of structures is mainly ascribed to the lanthanide contraction effect. Compound 1 consists of a 3D network with an alpha-polonium-like Ag(+)-homometallic net and helical La(3+) chain. Compounds 2-5 display a 2D honeycomb-like structure with 18-membered Ln(3)Ag(3)O(12) motifs, and compounds 6-10 can be described as a sandwich-like 3D framework built of a 3D Ag(+)-homometallic net and 2D Ln(3+)-4(4) layer. In 4 (Sm), 5 (Eu), 7 (Tb), and 8 (Dy) samples, the efficient energy transfer from CAM to Ln(III) ions was observed, which results in the typical intense emissions of corresponding Ln(III) ions in the visible region, and the strongest emissions are (4)G(5/2) --> (6)H(7/2) (602 nm), (5)D(0) --> (7)F(2) (614 nm), (5)D(4) --> (7)F(5) (548 nm), and (4)F(9/2) --> (6)H(13/2) (576 nm) transitions. Variable-temperature magnetic susceptibility measurements of 6-10 show that the ferromagnetic interaction between gadolinium(III) ions appears in 6, whereas the mu(eff) values of 7-10 smoothly decrease on cooling. For the orbital contribution of Ln(III) ions, it is very difficult to determine the intrinsic magnetic interactions between Ln(III) ions.

  15. Role of Ag addition in L10 ordering of FePt-based nanocomposite magnets

    NASA Astrophysics Data System (ADS)

    Crisan, A. D.; Vasiliu, F.; Mercioniu, I.; Crisan, O.

    2014-01-01

    The FePt system has important perspectives as high-temperature corrosion-resistant magnets. In the form of rapidly solidified melt-spun ribbons, FePt-based magnets may exhibit in certain cases a two-phase hard-soft magnetic behaviour. The present paper deals with a microstructural and magnetic study of FePtAgB alloys with increasing Ag content. The aim is to identify and confirm the effect of Ag addition in decreasing the temperature of the FePt disorder-order structural phase transformation. A detailed high-resolution transmission electron microscopy study is employed, and the alternative disposal of hard and soft regions within the two-phase microstructure is observed and interpreted with respect to the X-ray diffraction results. In the as-cast Ag-containing samples, it is shown that there is an optimum of the Ag content for which best magnetic properties are obtained. Ag addition creates a nonlinear behaviour of the coercive field and the ordering parameter, similar to the RKKY interaction-induced interlayer exchange coupling (IEC) observed in magnetic layers separated by non-magnetic spacer layers. Direct formation of the L10 phase from the as-cast state in the FePtAgB alloys is reported with magnetic parameters compatible to other exchange spring permanent nanomagnets. These findings open novel perspectives into utilization of such alloys in applications requiring magnets operating in high-temperature industrial environments.

  16. Effects of Ru and Ag cap layers on microstructure and magnetic properties of FePt ultrathin films.

    PubMed

    Liu, Mingfeng; Jin, Tianli; Hao, Liang; Cao, Jiangwei; Wang, Ying; Wu, Dongping; Bai, Jianmin; Wei, Fulin

    2015-01-01

    The effects of Ru and Ag cap layers on the microstructure and magnetic properties of the FePt ultrathin films have been investigated. The results indicate that i) The Ag cap layer segregates from the FePt/Ag bilayer, lowers the FePt ordering temperature, promotes the FePt thin films to form island structure, and enhances the coercivity; ii) The Ru cap layer increases the FePt ordering temperature, helps to maintain smooth continuous structure film, and restrains the FePt (001) orientation and perpendicular magnetic anisotropy (PMA). The effects become more pronounced for the 3-nm-thick FePt thin films. The effects can be mainly attributed to the different melting point and thermal expansion stress between the cap layer and FePt thin films.

  17. Effects of Ru and Ag cap layers on microstructure and magnetic properties of FePt ultrathin films

    NASA Astrophysics Data System (ADS)

    Liu, Mingfeng; Jin, Tianli; Hao, Liang; Cao, Jiangwei; Wang, Ying; Wu, Dongping; Bai, Jianmin; Wei, Fulin

    2015-04-01

    The effects of Ru and Ag cap layers on the microstructure and magnetic properties of the FePt ultrathin films have been investigated. The results indicate that i) The Ag cap layer segregates from the FePt/Ag bilayer, lowers the FePt ordering temperature, promotes the FePt thin films to form island structure, and enhances the coercivity; ii) The Ru cap layer increases the FePt ordering temperature, helps to maintain smooth continuous structure film, and restrains the FePt (001) orientation and perpendicular magnetic anisotropy (PMA). The effects become more pronounced for the 3-nm-thick FePt thin films. The effects can be mainly attributed to the different melting point and thermal expansion stress between the cap layer and FePt thin films.

  18. Magnetic susceptibility, artifact volume in MRI, and tensile properties of swaged Zr-Ag composites for biomedical applications.

    PubMed

    Imai, Haruki; Tanaka, Yoji; Nomura, Naoyuki; Doi, Hisashi; Tsutsumi, Yusuke; Ono, Takashi; Hanawa, Takao

    2017-02-01

    Zr-Ag composites were fabricated to decrease the magnetic susceptibility by compensating for the magnetic susceptibility of their components. The Zr-Ag composites with a different Zr-Ag ratio were swaged, and their magnetic susceptibility, artifact volume, and mechanical properties were evaluated by magnetic balance, three-dimensional (3-D) artifact rendering, and a tensile test, respectively. These properties were correlated with the volume fraction of Ag using the linear rule of mixture. We successfully obtained the swaged Zr-Ag composites up to the reduction ratio of 96% for Zr-4, 16, 36, 64Ag and 86% for Zr-81Ag. However, the volume fraction of Ag after swaging tended to be lower than that before swaging, especially for Ag-rich Zr-Ag composites. The magnetic susceptibility of the composites linearly decreased with the increasing volume fraction of Ag. No artifact could be estimated with the Ag volume fraction in the range from 93.7% to 95.4% in three conditions. Young's modulus, ultimate tensile strength (UTS), and 0.2% yield strength of Zr-Ag composites showed slightly lower values compared to the estimated values using a linear rule of mixture. The decrease in magnetic susceptibility of Zr and Ag by alloying or combining would contribute to the decrease of the Ag fraction, leading to the improvement of mechanical properties.

  19. High-temperature magnetization anomaly in Co/Ag/Si(1 1 1) ultrathin films

    NASA Astrophysics Data System (ADS)

    Lin, J. Y.; Tsay, J. S.; Liou, Y.; Yao, Y. D.; Lee, S. F.; Yang, C. S.

    2000-01-01

    High-temperature magnetic properties of ultrathin Co/Ag/Si(1 1 1) films were studied by surface magneto-optic Kerr effect (SMOKE) in an ultra-high vacuum (UHV) chamber with a background pressure less than 1×10 -10 Torr. A 6 mono-layer (ML) Co layer was deposited on Si(1 1 1) surface with Ag as a buffer layer with the thickness being varied between 0 and 5.6 ML. Both polar and longitudinal MOKE (P- and LMOKE) were studied as a function of temperature between 300 and 550 K. It is interesting to note that the Kerr intensity of LMOKE for Co/Ag/Si(1 1 1) thin film with Ag thickness of 2.8 and 5.6 ML decreases with increasing temperature and vanishes near 475 K; it shows up again in the opposite direction above 475 K before vanishing again at 550 K. This was not observed for samples with Ag thickness less than 2.8 ML. This indicates that the Ag buffer layer is playing an important role in the variation of magnetization of Co at high temperature; in other words, stress or small Co/Co-Ag clusters formed by the diffusion between Ag and Co layer at high temperature may cause the magnetization anomaly.

  20. Structural, thermal and magnetic investigations on immiscible Ag-Co nanocrystalline alloy with addition of Mn

    NASA Astrophysics Data System (ADS)

    Mondal, B. N.; Chabri, S.; Sardar, G.; Nath, D. N.; Chattopadhyay, P. P.

    2016-08-01

    50Ag-50Co (at%) and 40Ag-40Co-20Mn (at%) alloys prepared by ball milling up to 50 h and subsequent isothermal annealing at the temperature range of 350-650 °C for 1 h has been investigated systematically. Mn promotes early formation of the nanostructures and solid solutions of the alloys by ball milling. In contrast, annealing at 350 °C of Ag-Co alloy resulted the dissolution of hcp Co. Annealing above 350 °C decomposes the metastable Ag-Co alloy into the polycrystalline and segregated Ag and fcc Co. Enthalpy of mixing of both the alloy has increased with increase in milling time. Both the nanocrystalline alloys prepared by ball milling and annealing have been revealed the ferromagnetic behavior. The most significant improvement of magnetic properties is yielded in as-milled Ag-Co-Mn alloy obtained after annealing at 550 °C for 1 h.

  1. Preparation of Ag deposited TiO2 (Ag/TiO2) composites and investigation on visible-light photocatalytic degradation activity in magnetic field

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Ma, C. H.; Wang, J.; Li, S. G.; Li, Y.

    2014-12-01

    In this study, Ag deposited TiO2 (Ag/TiO2) composites were prepared by three different methods (Ultraviolet Irradiation Deposition (UID), Vitamin C Reduction (VCR) and Sodium Borohydride Reduction (SBR)) for the visible-light photocatalytic degradation of organic dyes in magnetic field. And then the prepared Ag deposited TiO2 (Ag/TiO2) composites were characterized physically by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The visible-light photocatalytic activities of these three kinds of Ag deposited TiO2 (Ag/TiO2) composites were examined and compared through the degradation of several organic dyes under visible-light irradiation in magnetic field. In addition, some influence factors such as visible-light irradiation time, organic dye concentration, revolution speed, magnetic field intensity and organic dye kind on the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composite were reviewed. The research results showed that the presence of magnetic field significantly enhanced the visible-light photocatalytic activity of Ag deposited TiO2 (Ag/TiO2) composites and then contributed to the degradation of organic dyes.

  2. Magnetic and magnetotransport properties of nanocrystalline Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30 alloys prepared by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Gómez, J. A.; Xia, S. K.; Passamani, E. C.; Giordanengo, B.; Baggio-Saitovitch, E. M.

    2001-01-01

    The magnetic and magnetotransport properties of nanocrystalline Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30 alloys have been studied by Mössbauer spectroscopy, magnetization and resistivity measurements. The samples were prepared by mechanical alloying of Fe and Ag powders in a high-energy ball mill. Mössbauer spectroscopy and magnetic measurements of the final milled samples indicate the presence of single-domain 'Fe' particles. The magnetoresistance values, at 4.2 K and for a magnetic field of 8 T, are 2.5% and 5.7% for samples Ag 0.85Fe 0.15 and Ag 0.70Fe 0.30, respectively. The magnetoresistance behavior indicates the cluster-glass-like features in both the final milled samples.

  3. Multiple magnetic transitions in Ag-substituted DyPt2

    NASA Astrophysics Data System (ADS)

    Arora, Parul; Chattopadhyay, M. K.; Sharath Chandra, L. S.; Sharma, V. K.; Roy, S. B.

    2012-08-01

    We show that the partial substitution of Ag in place of Pt in the cubic Laves phase ferromagnetic (below 9.2 K) compound DyPt2 leads to multiple temperature and field induced magnetic phase transitions. We study these phase transitions in details in a Dy(Pt0.94Ag0.06)2 alloy with the help of magnetization and specific heat measurements. One of the magnetic transitions produces an unusually sharp peak in the temperature dependence of heat capacity of Dy(Pt0.94Ag0.06)2, which is not observed in either of the parent compounds DyPt2 or DyAg2. The shape of this peak resembles those observed in the temperature dependence of heat capacity of the rare earth elements and some rare-earth based alloys and compounds across first order magnetic transitions accompanied by magneto-elastic effects and structural changes. The magnetic properties of Dy(Pt0.94Ag0.06)2 are analyzed in terms of the enhancement of crystal field effect and quadrupolar interactions. Large magneto-elastic coupling resulting from these interactions and changes in the electronic density of states near Fermi level because of the chemical substitution seem to introduce into the system the temperature and field induced multiple magnetic phase transitions mentioned above.

  4. FePt-Ag nanocomposite thin films with longitudinal magnetic anisotropy.

    PubMed

    Zhou, Y Z; Chen, J S; Chow, G M; Wang, J P

    2004-09-01

    A well-controlled method to fabricate FePt thin films with the (200) texture and longitudinal magnetic anisotropy for high-density magnetic recording media is reported. FePt-Ag nanocomposite thin films with L1(0) ordered FePt grains embedded in an Ag matrix were deposited on the Cr90Ru10/glass by co-sputtering from Ag and FePt targets. The Ag doping suppressed the (001) texture but improved the L1(0) FePt (200) texture. The magnetic easy axis of FePt-Ag thin films changed from perpendicular to longitudinal in direction. In-plane coercivity of the films varied from 0.8 kOe to 6.5 kOe, depending on Ag contents in the films and under-layer thickness. The change from the (001) to (200) texture could be due to the competition of grain-boundary energy and epitaxial-strain energy.

  5. Magneto-optical and catalytic properties of Fe3O4@HA@Ag magnetic nanocomposite

    NASA Astrophysics Data System (ADS)

    Amir, Md.; Güner, S.; Yıldız, A.; Baykal, A.

    2017-01-01

    Fe3O4@HA@Ag magnetic nanocomposites (MNCs) were successfully synthesized by the simple reflux method for the removal of azo dyes from the industrial aqueous media. Fe3O4@HA@AgMNCs exhibited high catalytic activity to reduce MB within 20 min from the waste water. The obtained materials were characterized by the means of different techniques. Powder X-ray diffraction (XRD) analysis confirmed the single-phase of Fe3O4 spinel structure. SEM and TEM analysis indicated that Fe3O4@HA@AgMNCs were nanoparticles like structure with small agglomeration. TG result showed that the products contained 9% of HA. The characteristic peaks of HA at 1601 cm-1 and 1703 cm-1 was observed by the means of FT-IR spectra of Fe3O4@HA@AgMNCs. The hysteresis (σ-H) curves revealed Fe3O4@HA@Ag MNCs exhibit a typical superparamagnetic characteristic with a saturation magnetization of 59.11 emu/g and measured magnetic moment is 2.45 μB. The average magnetic particle dimension (Dmag) is 13.25 nm. In accordance, the average crystallite and particle dimensions were obtained as 11.50 nm and 13.10 nm from XRD and TEM measurements, respectively. Magnetocrystalline anisotropy was offered as uniaxial and calculated effective anisotropy constant (Keff) is 2.96×105 Erg/g. The blocking temperature was estimated as 522 K. The size-dependent saturation magnetization suggests the existence of a magnetically dead layer as 0.793 nm for Fe3O4@HA@Ag MNCs. The UV-vis diffuse reflectance spectroscopy (DRS) and Kubelka-Munk theory were applied to determine the optical properties of powder samples. The direct optical energy band gap (Eg) values were estimated from Tauc plots between 1.62 eV and 2.12 eV.

  6. Direct observation of enhanced magnetic moments in Fe/Ag(100)

    NASA Astrophysics Data System (ADS)

    Wooten, C. L.; Chen, J.; Mulhollan, G. A.; Erskine, J. L.; Markert, J. T.

    1994-04-01

    The magnetic properties of ultrathin (1-5 monolayer) Fe films on Ag(100) substrates were investigated using SQUID magnetometry. Films were grown in pairs (one bulklike, the other thin), and characterized in situ by low-energy electron diffraction, Auger spectroscopy, and the surface magneto-optic Kerr effect. The films were than capped with Au and studied with a SQUID magnetometer over the temperature range 2-340 K. We report here a direct observation of enhanced magnetic moments for Fe on Ag(100), with interface moments enhanced as much as 29%.

  7. Growth Mechanism and Electrical and Magnetic Properties of Ag-Fe₃O₄ Core-Shell Nanowires.

    PubMed

    Ma, Jingjing; Wang, Kai; Zhan, Maosheng

    2015-07-29

    One-dimensional Ag-Fe3O4 core-shell heteronanowires have been synthesized by a facile and effective coprecipitation method, in which silver nanowires (AgNWs) were used as the nucleation site for growth of Fe3O4 in aqueous solution. The size and morphology control of the core-shell nanowires were achieved by simple adjustments of reaction conditions including FeCl3/FeCl2 concentration, poly(vinylpyrrolidone) (PVP) concentration, reaction temperature, and time. It was found that the Fe3O4 shell thickness could be tuned from 6 to 76 nm with the morphology variation between nanopheres and nanorods. A possible growth mechanism of Ag-Fe3O4 core-shell nanowires was proposed. First, the C═O derived from PVP on the surface of AgNWs provided nucleation points and in situ oxidation reaction between AgNWs and FeCl3/FeCl2 solution promoted the accumulation of Fe(3+) and Fe(2+) on the AgNWs surface. Second, Fe3O4 nanoparticles nucleated on the AgNWs surface. Lastly, Fe3O4 nanoparticles grew on the AgNWs surface by using up the reagents. Higher FeCl3/FeCl2 concentration or higher temperature led to faster nucleation and growth, resulting in the formation of Fe3O4 nanorods, whereas lower concentration or lower temperature resulted in slower nucleation and growth, leading to the formation of Fe3O4 nanospheres. Furthermore, the Ag-Fe3O4 core-shell nanowires exhibited good electrical properties and ferromagnetic properties at room temperature. Particularly, the magnetic saturation values (Ms) increased from 5.7 to 26.4 emu g(-1) with increasing Fe3O4 shell thickness from 9 to 76 nm. This growth of magnetic nanoparticles on 1D metal nanowires is meaningful from both fundamental and applied perspectives.

  8. Microstructure and jc Improvements in Multifilamentary Bi-2212/Ag Wires for High Field Magnet Applications

    NASA Astrophysics Data System (ADS)

    Miao, H.; Meinesz, M.; Czabaj, B.; Parrell, J.; Hong, S.

    2008-03-01

    Bi-2212/Ag conductor is one of the most promising materials for extending the field strength of superconducting magnets over present low temperature superconductor systems. From the view point of practical application, Bi-2212/Ag round wires have significant advantages over more typical HTS tape conductors, such as no anisotropy, and easier handling and coil winding, which allows considerable flexibility in the magnet design. Recent development efforts at Oxford Superconducting Technology have been aimed at manufacturing high quality multifilamentary Bi-2212/Ag round wires with the varied sizes to fabricate HTS insert coils for high field magnet applications. However, further improvement of critical current density (Jc) and engineering current density (JE) in larger diameter wires is desirable for practical applications. Recent results show a strong dependence of the wire JE and Jc performance on its microstructure, in particularly, the interface of Bi-2212/Ag. Significant improvements of microstructure and Jc have resulted from the optimization of wire size and filament numbers, but not obviously on starting powder fill factors. The highest JE of 320 A/mm2 (non-Ag Jc of 1103 A/mm2) at 4.2 K, 25 T was obtained in 1.15 mm wire with 85×19 filament configuration.

  9. Magnetic Rotation in {sup 106}Ag and Systematics of A{approx}110 Mass Region

    SciTech Connect

    He, C. Y.; Zhu, L. H.; Wu, X. G.; Wen, S. X.; Li, G. S.; Liu, Y.; Wang, Z. M.; Li, X. Q.; Ma, R. G.; Yang, C. X.; Cui, X. Z.

    2008-11-11

    The high spin states of {sup 106}Ag were populated via the fusion-evaporation reaction {sup 100}Mo({sup 11}B,5n){sup 106}Ag at a beam energy of 60 MeV. A new level scheme of {sup 106}Ag is built on basis of the present experiment. The positive parity band with the configuration of {pi}g{sub 9/2} x V[h{sub 11/2}{sup 2}(g{sub 7/2}/d{sub 5/2})] is discussed on the ground of shears mechanism. Theoretical calculation of the effective interaction performed by TAC model agrees well with the experimental value. Systematics study shows that Ag isotopes are probably at the boundary of magnetic rotation in A{approx}110 mass region.

  10. Geodynamics branch data base for main magnetic field analysis

    NASA Technical Reports Server (NTRS)

    Langel, Robert A.; Baldwin, R. T.

    1991-01-01

    The data sets used in geomagnetic field modeling at GSFC are described. Data are measured and obtained from a variety of information and sources. For clarity, data sets from different sources are categorized and processed separately. The data base is composed of magnetic observatory data, surface data, high quality aeromagnetic, high quality total intensity marine data, satellite data, and repeat data. These individual data categories are described in detail in a series of notebooks in the Geodynamics Branch, GSFC. This catalog reviews the original data sets, the processing history, and the final data sets available for each individual category of the data base and is to be used as a reference manual for the notebooks. Each data type used in geomagnetic field modeling has varying levels of complexity requiring specialized processing routines for satellite and observatory data and two general routines for processing aeromagnetic, marine, land survey, and repeat data.

  11. AGS Fast spin resonance jump, magnets and power supplies

    SciTech Connect

    Glenn,J.W.; Huang, H.; Liaw, C. J.; Marneris, I.; Meng, W.; Mi, J. L.; Rosas, P.; Sandberg, J.; Tuozzolo, J.; Zhang, A.

    2009-05-04

    In order to cross more rapidly the 82 weak spin resonances caused by the horizontal tune and the partial snakes, we plan to jump the horizontal tune 82 times during the acceleration of polarized protons. The current in the magnets creating this tune jump will rise in 100 {micro}s, hold flat for about 4 ms and fan to zero in 100 {micro}s. Laminated beam transport quadrupole magnets have been recycled by installing new two turn coils and longitudinal laminated pole tip shims that reduce inductance and power supply current. The power supply uses a high voltage capacitor discharge to raise the magnet current, which is then switched to a low voltage supply, and then the current is switched back to the high voltage capacitor to zero the current. The current in each of the magnet pulses must match the order of magnitude change in proton momentum during the acceleration cycle. The magnet, power supply and operational experience are described.

  12. Magnetic and electronic structure of Mn nanostructures on Ag(111) and Au(111)

    NASA Astrophysics Data System (ADS)

    Cardias, R.; Bezerra-Neto, M. M.; Ribeiro, M. S.; Bergman, A.; Szilva, A.; Eriksson, O.; Klautau, A. B.

    2016-01-01

    We present results of the electronic and magnetic structure of Mn nanowires adsorbed on Ag(111) and Au(111) surfaces. For finite Mn nanowires on Ag(111) and Au(111) surfaces, our ab initio results show that the large difference between the spin-orbit splitting of these two surfaces leads to completely different magnetic configurations. The magnetic ordering for Mn nanowires adsorbed on Ag(111) is governed by the strong exchange interaction between Mn adatoms. For Mn nano-chains on Au(111), the competition between Heisenberg and Dzyaloshinskii-Moriya interactions leads to a complex magnetic structure of the clusters considered here. Among the more conspicuous results we note a spin-spiral helical type for the nanowire with seven atoms, and a complex magnetic configuration incommensurate with the substrate lattice for a double-sized Mn wire. The effect of the structural relaxation is also investigated, showing sensitivity of the exchange interactions to the bond distance to the substrate. We also demonstrate that small changes in the band filling of these Mn chains results in drastically different changes of the interatomic exchange. Finally, we show that dispersion of the electronic energy spectrum is possible even in nanostructures with bounded spatial extension.

  13. Magnetic properties of iron adatoms and small iron clusters on Ag(1 0 0)

    NASA Astrophysics Data System (ADS)

    Lazarovits, B.; Szunyogh, L.; Weinberger, P.

    2002-02-01

    A Green's function embedding technique based on the fully relativistic spin-polarized Screened Korringa-Kohn-Rostoker method is used to calculate the electronic and magnetic properties of magnetic nanostructures. Strongly enhanced spin and orbital moments are obtained for an Fe adatom and for small clusters of Fe on a Ag(1 0 0) surface. As a consequence, for an Fe adatom a magnetic anisotropy energy is found that is about 10 times larger than for an Fe monolayer. Furthermore, the exchange coupling energy between two Fe adatoms is calculated in terms of the force theorem, showing a very rapid decay with increasing distance.

  14. Megagauss Magnetic Field Sensors Based on Ag2Te

    SciTech Connect

    Stephen Mitchen; Allen L. Johnson; John W. Farley

    2006-11-30

    Pulsed power machines capable of producing tremendous energy face various diagnostic and characterizing challenges. Such devices, which may produce 10 - 100MAs, have traditionally relied on Faraday rotation and Rogowski coil technology for time-varying current measurements. Faraday rotation requires a host of costly optical components, including fibers, polarizers, retarders, lasers, and detectors, as well as setup, alignment, and time-consuming post-processing to unwrap the time-dependent current signal. Rogowski coils face potential problems such as physical distortion to the sensor itself due to the tremendous strain caused by magnetically induced pressures, which is proportional to the magnetic field squared (B2). Electrical breakdown in the intense field region is also a major concern. Other related challenges include, but are not limited to, bandwidth and inductance limitations and susceptibility issues related to electrical magnetic interference (EMI).

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

    SciTech Connect

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

    2009-04-01

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

  16. Magnet reliability in the Fermilab Main Injector and implications for the ILC

    SciTech Connect

    Tartaglia, M.A.; Blowers, J.; Capista, D.; Harding, D.J.; Kiemschies, O.; Rahimzadeh-Kalaleh, S.; Tompkins, J.C.; /Fermilab

    2007-08-01

    The International Linear Collider reference design requires over 13000 magnets, of approximately 135 styles, which must operate with very high reliability. The Fermilab Main Injector represents a modern machine with many conventional magnet styles, each of significant quantity, that has now accumulated many hundreds of magnet-years of operation. We review here the performance of the magnets built for this machine, assess their reliability and categorize the failure modes, and discuss implications for reliability of similar magnet styles expected to be used at the ILC.

  17. Controllable optical activity of non-spherical Ag and Co SERS substrate with different magnetic field

    NASA Astrophysics Data System (ADS)

    Fan, Chun-Zhen; Zhu, Shuang-Mei; Xin, Hao-Yi

    2017-02-01

    We experimentally fabricate a non-spherical Ag and Co surface-enhanced Raman scattering (SERS) substrate, which not only retains the metallic plasmon resonant effect, but also possesses the magnetic field controllable characteristics. Raman detections are carried out with the test crystal violet (CV) and rhodamine 6G (R6G) molecules with the initiation of different magnitudes of external magnetic field. Experimental results indicate that our prepared substrate shows a higher SERS activity and magnetic controllability, where non-spherical Ag nanoparticles are driven to aggregate effectively by the magnetized Co and plenty of hot-spots are built around the metallic Ag nanoparticles, thereby leading to the enhancement of local electromagnetic field. Moreover, when the external magnetic field is increased, our prepared substrate demonstrates excellent SERS enhancement. With the 2500 Gs and 3500 Gs (1 Gs = 10‑4 T) magnetic fields, SERS signal can also be obtained with the detection limit lowering down to 10‑9 M. These results indicate that our proposed magnetic field controlled substrate enables us to freely achieve the enhanced and controllable SERS effect, which can be widely used in the optical sensing, single molecule detection and bio-medical applications. Project supported by the Key Science and Technology Research Project of Henan Province, China (Grant No. 162102210164), the Natural Science Foundation of Henan Educational Committee, China (Grant No. 17A140002), the National Natural Science Foundations of China (Grant Nos. 11574276, 11404291, and 11604079), and the Program for Science & Technology Innovation Talents in Universities of Henan Province, China (Grant No. 17HASTIT0).

  18. Uniform magnetization reversal in dual main-phase (Ce,Nd)2Fe14B sintered magnets with inhomogeneous microstructure

    NASA Astrophysics Data System (ADS)

    Zhang, Le-le; Li, Zhu-bai; Zhang, Xue-feng; Ma, Qiang; Liu, Yan-li; Li, Yong-feng; Zhao, Qian

    2017-02-01

    The element distribution and the magnetic properties were investigated in (Ce,Nd)-Fe-B sintered magnets prepared by mixing Nd13.5Fe80B6.5 and Ce9Nd4.5Fe80B6.5 powders with different mass ratios. Two main phases exist, but element diffusion is evident, and the chemical composition of the main phase is widely different from that of the master alloy. The Ce element tends to be expelled from the Ce-rich Re2Fe14B phase. Compared with the Ce-rich main phase, the Nd-rich Re2Fe14B phase is more stable in structure. Although the microstructure is inhomogeneous and the magnetocrystalline anisotropy is variable, the magnetization reversal is uniform in these dual main-phase magnets, which should ascribe to the existence of the exchange coupling, and magnetization reversal undergoes the nucleation of the reversed domain in irreversible magnetization. It is expected to further improve the coercivity by optimizing the distribution of the Nd-rich main phase in preparing the resource-saving (Ce,Nd)2Fe14B sintered magnets.

  19. The design and manufacture of the Fermilab Main Injector Dipole Magnet

    SciTech Connect

    Brown, B.C.; Chester, N.S.; Harding, D.J.; Martin, P.S.

    1992-03-01

    Fermilab's new Main Injector Ring (MIR) will replace the currently operating Main Ring to provide 150 GeV Proton and Antiproton beams for Tevetron injection, and rapid cycling, high intensity, 120 GeV Proton beams for Antiproton production. To produce and maintain the required high beam quality, high intensity, and high repetition rate, conventional dipole magnets with laminated iron core and water cooled copper conductor were chosen as the bending magnet. A new magnet design having low inductance, large copper cross section, and field uniformity sufficient for high intensity injection and efficient slow resonant extraction, is required to obtain the needed geometric aperture, dynamic aperture, and operational reliability. The current Main Injector Ring lattice design requires the use of 344 of these magnets. 216 of these magnets are to be 6 m long, and 128 are to be 4 m long.

  20. The design and manufacture of the Fermilab Main Injector Dipole Magnet

    SciTech Connect

    Brown, B.C.; Chester, N.S.; Harding, D.J.; Martin, P.S.

    1992-03-01

    Fermilab`s new Main Injector Ring (MIR) will replace the currently operating Main Ring to provide 150 GeV Proton and Antiproton beams for Tevetron injection, and rapid cycling, high intensity, 120 GeV Proton beams for Antiproton production. To produce and maintain the required high beam quality, high intensity, and high repetition rate, conventional dipole magnets with laminated iron core and water cooled copper conductor were chosen as the bending magnet. A new magnet design having low inductance, large copper cross section, and field uniformity sufficient for high intensity injection and efficient slow resonant extraction, is required to obtain the needed geometric aperture, dynamic aperture, and operational reliability. The current Main Injector Ring lattice design requires the use of 344 of these magnets. 216 of these magnets are to be 6 m long, and 128 are to be 4 m long.

  1. Investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al alloy with Ag and Mn additions

    SciTech Connect

    Silva, R.A.G.; Paganotti, A.; Gama, S.; Adorno, A.T.; Carvalho, T.M.; Santos, C.M.A.

    2013-01-15

    The investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al, Cu-11%Al-3%Ag, Cu-11%Al-10%Mn and Cu-11%Al-10%Mn-3%Ag alloys was made using microhardness measurements, differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersion X-ray spectroscopy and magnetic moment change with applied field measurement. The results indicated that the Mn addition changes the phase stability range, the microhardness values and makes undetectable the eutectoid reaction in annealed Cu-11%Al and Cu-11%Al-3%Ag alloys while the presence of Ag does not modify the phase transformation sequence neither microhardness values of the annealed Cu-11%Al and Cu-11%Al-10%Mn alloys, but it increases the magnetic moment of this latter at about 2.7 times and decreases the rates of eutectoid and peritectoid reactions of the former. - Highlights: Black-Right-Pointing-Pointer The microstructure of Cu-Al alloy is modified in the Ag presence. Black-Right-Pointing-Pointer ({alpha} + {gamma}) phase is stabilized down to room temperature when Ag is added to Cu-Al alloy. Black-Right-Pointing-Pointer Ag-rich phase modifies the magnetic characteristics of Cu-Al-Mn alloy.

  2. SrAgZn and EuAgZn with KHg{sub 2}-type structure—Structure, magnetic properties, and {sup 151}Eu Mössbauer spectroscopy

    SciTech Connect

    Gerke, Birgit; Rodewald, Ute Ch.; Niehaus, Oliver; Pöttgen, Rainer

    2013-07-15

    Samples of SrAgZn and EuAgZn were synthesized by reaction of the elements in sealed tantalum crucibles. Both structures were refined on the basis of single crystal X-ray diffractometer data: KHg{sub 2}-type, Imma, a=476.7(1), b=780.9(2), c=810.1(2) pm, R{sub 1}/wR{sub 2}=0.0189/0.0119, 381 F² values for SrAg{sub 1.12}Zn{sub 0.88} and a=474.43(9), b=760.8(2), c=799.0(2) pm, R{sub 1}/wR{sub 2}=0.0226/0.0483, 370 F² values for EuAg{sub 1.17}Zn{sub 0.83} with 13 variables per refinement. Silver and zinc are randomly distributed on the Hg position and build up three-dimensional networks. EuAgZn shows ferromagnetic ordering at 29(1) K. In the temperature range from 75 to 300 K the sample shows Curie–Weiss behaviour with μ{sub eff}=7.87(1) μ{sub B}/Eu atom and θ{sub P}=37.1(1) K, indicating divalent europium. {sup 151}Eu Mössbauer spectroscopic measurements confirmed the divalent state with an isomer shift of −9.31 mm/s at 78 K. Temperature dependent {sup 151}Eu data show first magnetic hyperfine field splitting at 25 K and a saturated magnetization of 17 T at 5.2 K. The temperature dependence can be described by an S=7/2 Brillouin function. - Graphical abstract: The near neighbor coordination of the strontium and europium atoms in SrAg{sub 1.12}Zn{sub 0.88}, EuAg{sub 1.17}Zn{sub 0.83}, and EuAuZn. - Highlights: • Synthesis of new intermetallic zinc compounds SrAgZn and EuAgZn. • Ferromagnetic ordering of EuAgZn at 29 K. • Magnetic hyperfine field splitting in the {sup 151}Eu Mössbauer spectrum.

  3. Structure of positive parity bands and observation of magnetic rotation in 108Ag

    NASA Astrophysics Data System (ADS)

    Sethi, Jasmine; Palit, R.

    2015-10-01

    The interplay of nuclear forces among the neutron particles (holes) and proton holes (particles) in the odd-odd nuclei gives rise to a variety of shapes and hence novel modes of excitations. The odd-odd nuclei in the A ~ 110 region have proton holes in the g9/2 orbital and the neutron particles in the h11/2 orbitals. A systematic study of shears mechanism in A ~ 110 region indicates the presence of magnetic rotation (MR) phenomenon in Ag and In isotopes. Therefore, the structure of doubly odd 108Ag nucleus was probed in two different reactions, i.e, 100Mo(11B, 4n)108Ag at 39 MeV and 94Zr(18O, p3n)108Ag at 72 MeV beam energies. The emitted γ-rays were detected using the Indian National Gamma Array (INGA) at TIFR, Mumbai. A significant number of new transitions and energy levels were identified. Lifetime measurements, using the Doppler shift attenuation method, have been carried out for a positive parity dipole band. Tilted Axis Cranking (TAC) calculations have been performed for two positive parity dipole bands.

  4. Strength of Cu-28 wt%Ag composite solidified under high magnetic field followed by cold drawing

    NASA Astrophysics Data System (ADS)

    Zhao, Congcong; Zuo, Xiaowei; Wang, Engang; Han, Ke

    2017-03-01

    Cu-Ag composite is one of the best conductors for high-field magnets. Increasing its strength is crucial for designing newer high-field magnets. Cu-28 wt%Ag samples were solidified with and without a 12-T high magnetic field (HMF), and then cold-drawn. We investigated the influence of HMF on microstructure, hardness and strength of Cu-Ag samples both before and after cold-drawing. The introduction of external HMF during solidification increased both the dendrite arm spacing and the dissolved Ag in Cu, and it reduced the spacing between both the Ag precipitates in proeutectic Cu and the eutectic lamellae. The transversal microstructure after cold-drawing inherited the network solidification structure, but at a refined scale. The Cu dendrite spacing in the 12-T HMF samples at all deformation strain was larger than that without HMF. HMF slightly increased the intensity of <111> fiber texture of Cu, which strengthened proeutectic Cu at the level of 3.5 deformation strain. In samples deformed to strain of 3.5, refined Ag precipitation spacing, increased Ag solubility in Cu matrix, and refined eutectic lamellar spacing by 12-T HMF increased the strength by 5% in the sample compared with that without HMF.

  5. Effect of Ag underlayer on microstructures and perpendicular magnetic properties of CoPt nanocomposite thin films.

    PubMed

    Shen, C L; Kuo, P C; Li, Y S; Lin, G P; Huang, K T; Ou, S L; Chen, S C

    2011-12-01

    CoPt/Ag films were prepared by magnetron sputtering on glass substrates and subsequent annealing. The dependence of degree of ordering and magnetic properties on Ag film thickness and annealing conditions were investigated. It was found that the Ag underlayer played a dominant role in inducing the (001) texture of the CoPt film after annealing. CoPt films with a thickness about 20 nm and Ag underlayers with a thickness about 70 nm are easy to obtain a large degree of ordering and a perpendicular magnetic anisotropy after annealing at 700 degrees C for 30 min. CoPt/Ag films with out-of-plane coercivity (Hc (perpendicular)) in the range of 13.5-14.0 kOe and a out-of-plane squareness (S(perpendicular)) of 0.97 were obtained after annealing at 700 degrees C for 30 min. Ag underlayer is beneficial to enhance the Hc(perpendicular)and S(perpendicular) of CoPt film significantly. The degree of ordering and perpendicular magnetic properties of the CoPt films which deposited on Ag underlayer are larger than those of the single layer CoPt films.

  6. Effect of magnetic field on the photovoltaic properties of YBa2Cu3O6.96/Ag heterojunction

    NASA Astrophysics Data System (ADS)

    Yang, Feng; Han, Mengyuan; Chu, Zhuang; Ma, Zhipan; Chang, Fanggao

    2017-02-01

    The obvious photovoltaic effect (Voc ˜ 30 μV) induced by purple-laser illumination at high Tc superconductor YBa2Cu3O6.96/Ag (YBCO/Ag) heterojunction has been observed, revealing that there exists an electrical field across the YBCO/Ag interface. It has been found that magnetic field can dramatically change the photo-induced voltage in the vicinity of superconducting transition. With increasing magnetic fields up to 3 T, the photovoltage at 74 K and 30 mW/mm2 is reduced from 15 μV to zero and then reaches -15 μV. The polarity of the voltage can be switched by applying an external magnetic field, as well as by varying the laser intensity. Our results can be understood in terms of the magnetic vortex penetrating in high Tc superconductors and provide strong evidence for the existence of an interface electrical field in the superconductor/metal heterojunction.

  7. Ultrasonic-assisted preparation of novel ternary ZnO/AgI/Fe3O4 nanocomposites as magnetically separable visible-light-driven photocatalysts with excellent activity.

    PubMed

    Shekofteh-Gohari, Maryam; Habibi-Yangjeh, Aziz

    2016-01-01

    The present work demonstrates preparation of novel ternary ZnO/AgI/Fe3O4 nanocomposites, as magnetically separable visible-light-driven photocatalysts using ultrasonic irradiation method. The XRD, EDX, SEM, TEM, UV-vis DRS, FT-IR, PL, and VSM techniques was applied for characterization of structure, purity, morphology, optical, and magnetic properties of the resultant samples. The superior activity was seen for the nanocomposite with 8 weight ratio of ZnO/AgI to Fe3O4 in degradation of rhodamine B under visible-light irradiation. Photocatalytic activity of this nanocomposite in degradation of rhodamine B, methylene blue, and methyl orange is about 32, 6, and 5-fold higher than that of the ZnO/Fe3O4 nanocomposite. The highly enhanced activity of the ternary magnetic photocatalyst was mainly attributed to more visible-light absorption ability and efficiently separation of the charge carriers. Furthermore, it was revealed that the ultrasonic irradiation time and calcination temperature affect largely on the photocatalytic activity. Finally, the magnetic photocatalyst was successfully separated from the treated solution using external magnetic field.

  8. Silanization of Ag-deposited magnetite particles: an efficient route to fabricate magnetic nanoparticle-based Raman barcode materials.

    PubMed

    Kim, Kwan; Choi, Jeong-Yong; Lee, Hyang Bong; Shin, Kuan Soo

    2010-07-01

    Silica-coated Ag nanostructures usable as magnetic nanoparticle-based Raman barcode materials were developed. Initially, 283 nm sized spherical magnetite particles composed of 13 nm sized superparamagnetic Fe(3)O(4) nanoparticles were synthesized, and silver deposition was conducted using butylamine as the reductant of AgNO(3) in ethanol. The Ag-deposited Fe(3)O(4) (Fe(3)O(4)@Ag) particles are found to be efficient surface-enhanced Raman scattering (SERS) substrates with the enhancement factor at 632.8 nm excitation to be about 3 x 10(6). After SERS markers such as benzenethiol, 4-mercaptotoluene, 4-aminobenzenethiol, and 4-nitrobenzenethiol were adsorbed onto the silver surface, poly(allylamine hydrochloride) (PAH) was coated onto them using the layer-by-layer deposition method such that a subsequent base-catalyzed silanization could readily form a 60 nm thick silica shell around the PAH layer by a biomimetic process. The cross-linked silica shells effectively prevented the SERS-marker molecules from being liberated from the surface of the Fe(3)O(4)@Ag particles. Although the gram magnetization decreased nearly to one-half of the initial value because of coating with silver and silica, the remaining magnetization was nonetheless strong enough for the silica-coated Fe(3)O(4)@Ag particles to be used as barcode materials operating via SERS.

  9. Relativistic effects on the nuclear magnetic shielding in the MF (M=Cu, Ag, Au) series

    SciTech Connect

    David, Jorge; Restrepo, Albeiro

    2007-11-15

    Relativistic effects on the nuclear magnetic shielding {sigma}(M) of the series of diatomics MF (M=Cu, Ag, Au) are calculated and analyzed using the Dirac-Hartree-Fock (DHF) method in the random phase approximation (RPA). Significant differences due to relativistic effects on the shielding constant {sigma}(M) are found in this series of atoms. The high electronegativity of the fluorine atom works in conjunction with the spin-orbit coupling to increase the calculated value for {sigma}(Au). An unusually large diamagnetic contribution to the shielding constant is observed. Nonrelativistic nuclear magnetic shielding [{sigma}{sup NR}(M)] shows very good linear correlation with the nuclear charge (Z) of the metal, while the relativistic shielding [{sigma}{sup rel}(M)] varies as Z{sup 2.26}.

  10. Reduction of Marine Magnetic Data for Modeling the Main Field of the Earth

    NASA Technical Reports Server (NTRS)

    Baldwin, R. T.; Ridgway, J. R.; Davis, W. M.

    1992-01-01

    The marine data set archived at the National Geophysical Data Center (NGDC) consists of shipborne surveys conducted by various institutes worldwide. This data set spans four decades (1953, 1958, 1960-1987), and contains almost 13 million total intensity observations. These are often less than 1 km apart. These typically measure seafloor spreading anomalies with amplitudes of several hundred nanotesla (nT) which, since they originate in the crust, interfere with main field modeling. The source for these short wavelength features are confined within the magnetic crust (i.e., sources above the Curie isotherm). The main field, on the other hand, is of much longer wavelengths and originates within the earth's core. It is desirable to extract the long wavelength information from the marine data set for use in modeling the main field. This can be accomplished by averaging the data along the track. In addition, those data which are measured during periods of magnetic disturbance can be identified and eliminated. Thus, it should be possible to create a data set which has worldwide data distribution, spans several decades, is not contaminated with short wavelengths of the crustal field or with magnetic storm noise, and which is limited enough in size to be manageable for the main field modeling. The along track filtering described above has proved to be an effective means of condensing large numbers of shipborne magnetic data into a manageable and meaningful data set for main field modeling. Its simplicity and ability to adequately handle varying spatial and sampling constraints has outweighed consideration of more sophisticated approaches. This filtering technique also provides the benefits of smoothing out short wavelength crustal anomalies, discarding data recorded during magnetically noisy periods, and assigning reasonable error estimates to be used in the least square modeling. A useful data set now exists which spans 1953-1987.

  11. The Fermilab Main Injector Dipole construction techniques and prototype magnet measurements

    SciTech Connect

    Bleadon, M.E.; Brown, B.C.; Chester, N.S.; Desavouret, E.; Garvey, J.D.; Glass, H.D.; Harding, D.J.; Harfoush, F.A.; Holmes, S.D.; Humbert, J.C. )

    1992-01-01

    The Fermilab Main Injector Project will provide 120-150 GeV Proton and Antiproton Beams for Fermilab Fixed Target Physics and Colliding Beams Physics use. A dipole magnet has been designed and prototypes constructed for the principal bending magnets of this new accelerator. In this paper the design considerations and fabrication techniques are described. Measurement results on prototypes are reported, emphasizing the field uniformity achieved in both body field and end field at excitation levels from injection at 0.1 T to full field of 1.7 T.

  12. The Fermilab main injector dipole construction techniques and prototype magnet measurements

    SciTech Connect

    Bleadon, M.; Brown, B.; Chester, N.; Desavouret, E.; Garvey, J.; Glass, H.; Harding, D.; Harfoush, F.; Holmes, S.; Humbert, J.; Kerby, J.; Knauf, A.; Kobliska, G.; Lipski, A.; Martin, P.; Mazur, P.; Orris, D.; Ostiguy, J.; Peggs, S.; Pachnik, J.; Pewitt, E.; Satti, J.; Schmidt, E.; Sim, J.; Snowdon, S.; Walbridge, D.

    1991-09-01

    The Fermilab Main Injector Project will provide 120--150 GeV Proton and Antiproton Beams for Fermilab Fixed Target Physics and Colliding Beams Physics use. A dipole magnet has been designed and prototypes constructed for the principal bending magnets of this new accelerator. The design considerations and fabrication techniques are described. Measurement results on prototypes are reported, emphasizing the field uniformity achieved in both body field and end field at excitation levels from injection at 0.1 T to full field of 1.7 T. 6 refs., 5 figs., 3 tabs.

  13. Main magnetic field of Jupiter and its implications for future orbiter missions

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.; Ness, N. F.

    1975-01-01

    A very strong planetary magnetic field and an enormous magnetosphere with extremely intense radiation belts exist at Jupiter. Pioneer 10 and 11 fly-bys confirmed and extended the earlier ground based estimates of many of these characteristics but left unanswered or added to the list of several important and poorly understood features: the source mechanism and location of decametric emissions, and the absorption effects by the natural satellites Amalthea, Io, Europa and Ganymede. High inclination orbits (exceeding 60 deg) with low periapses (less than 2 Jupiter radii) are required to map the radiation belts and main magnetic field of Jupiter accurately so as to permit full investigation of these and associated phenomena.

  14. Study of road dust magnetic phases as the main carrier of potentially harmful trace elements.

    PubMed

    Bourliva, Anna; Papadopoulou, Lambrini; Aidona, Elina

    2016-05-15

    Mineralogical and morphological characteristics and heavy metal content of different fractions (bulk, non-magnetic fraction-NMF and magnetic fraction-MF) of road dusts from the city of Thessaloniki (Northern Greece) were investigated. Main emphasis was given on the magnetic phases extracted from these dusts. High magnetic susceptibility values were presented, whereas the MFs content of road dust samples ranged in 2.2-14.7 wt.%. Thermomagnetic analyses indicated that the dominating magnetic carrier in all road dust samples was magnetite, while the presence of hematite and iron sulphides in the investigated samples cannot be excluded. SEM/EDX analyses identified two groups of ferrimagnetic particles: spherules with various surface morphologies and textures and angular/aggregate particles with elevated heavy metal contents, especially Cr. The road dusts (bulk samples) were dominated by calcium, while the mean concentrations of trace elements decreased in the order Zn > Mn > Cu > Pb > Cr > Ni > V > Sn > As > Sb > Co > Mo > W > Cd. MFs exhibited significantly higher concentrations of trace elements compared to NMFs indicating that these potentially harmful elements (PHEs) are preferentially enriched in the MFs and highly associated with the ferrimagnetic particles. Hazard Index (HI) obtained for both adults and children through exposure to bulk dust samples were lower or close to the safe level (=1). On the contrary, the HIs for the magnetic phases indicated that both children and adults are experiencing potential health risk since HI for Cr was significantly higher than safe level. Cancer risk due to road dust exposure is low.

  15. EDDY CURRENT EFFECT OF THE BNL-AGS VACUUM CHAMBER ON THE OPTICS OF THE BNL-AGS SYNCHROTRON.

    SciTech Connect

    TSOUPAS,N.; AHRENS,L.; BROWN,K.A.; GLENN,J.W.; GARDNER,K.

    1999-03-29

    During the acceleration cycle of the AGS synchrotron, eddy currents are generated within the walls of the vacuum chambers of the AGS main magnets. The vacuum chambers have elliptical cross section, are made of inconel material with a wall thickness of 2 mm and are placed within the gap of the combined-function main magnets of the AGS synchrotron. The generation of the eddy currents in the walls of the vacuum chambers, creates various magnetic multipoles, which affect the optics of the AGS machine. In this report these magnetic multipoles are calculated for various time interval starting at the acceleration cycle, where the magnetic field of the main magnet is {approx}0.1 T, and ending before the beam extraction process, where the magnetic field of the main magnet is almost constant at {approx}1.1 T. The calculations show that the magnetic multipoles generated by the eddy-currents affect the optics of the AGS synchrotron during the acceleration cycle and in particular at low magnetic fields of the main magnet. Their effect is too weak to affect the optics of the AGS machine during beam extraction at the nominal energies.

  16. Visible-light-driven photocatalytic inactivation of Escherichia coli by magnetic Fe2O3-AgBr.

    PubMed

    Ng, Tsz Wai; Zhang, Lisha; Liu, Jianshe; Huang, Guocheng; Wang, Wei; Wong, Po Keung

    2016-03-01

    Bacterial inactivation by magnetic photocatalyst receives increasing interests for the ease recovery and reuse of photocatalysts. This study investigated bacterial inactivation by a magnetic photocatalysts, Fe2O3-AgBr, under the irradiation of a commercially available light emitting diode lamp. The effects of different factors on the inactivation of Escherichia coli were also evaluated, in term of the efficiency in inactivation. The results showed that Fe2O3-AgBr was able to inactivate both Gram negative (E. coli) and Gram positive (Staphylococcus aureus) bacteria. Bacterial inactivation by Fe2O3-AgBr was more favorable under high temperature and alkaline pH. Presence of Ca(2+) promoted the bacterial inactivation while the presence of [Formula: see text] was inhibitory. The mechanisms of photocatalytic bacterial inactivation were systemically studied and the effects of the presence of various specific reactive species scavengers and argon suggest that Fe2O3-AgBr inactivate bacterial cells by the oxidation of H2O2 generated from the photo-generated electron and direct oxidation of photo-generated hole. The detection of different reactive species further supported the proposed mechanisms. The results provide information for the evaluation of bacterial inactivation performance of Fe2O3-AgBr under different conditions. More importantly, bacterial inactivation for five consecutive cycles demonstrated Fe2O3-AgBr exhibited highly stable bactericidal activity and suggest that the magnetic Fe2O3-AgBr has great potential for water disinfection.

  17. 3D Design, Contruction, and Field Analysis of CIS Main Dipole Magnets

    NASA Astrophysics Data System (ADS)

    Berg, G. P. A.; Fox, W.; Friesel, D. L.; Rinckel, T.

    1997-05-01

    The lattice for CIS ( Cooler Injection Synchroton ) requires four laminated 90^circ main dipole magnets with bending radius ρ = 1.273 m, EFL = 2 m, and an edge angle of 12^circ. Optimum Cooler injection and injection in the planned 15 GeV LISS ring requires operation up to about 1.75 T. Initial operation of 1 Hz, with later upgrade to 5 Hz is planned. We will present 2D and 3D field calculations used to optimize the shape of laminations and endpacks of the magnet. Endpacks are designed to determine edge angle and to compensate hexapole components, in particular above 1.4 T where saturation becomes significant. The large dipole curvature required a new type of dipole construction. Each magnet consists of wedge shaped blocks fabricated from stamped lamination of cold rolled low carbon iron. B-stage (dry) epopy was used for bonding and insulation. The end blocks are machined to include the calculated 3D shape of the endpacks. All four magnets were mapped in the field range from 0.3 T - 1.8 T. Comparison of calculations and data in terms of B(I) curves, EFL, edge angle, and hexapole component as function of field excitation will be presented. The constructed magnets are well within expected specifications.

  18. Magnetic Activity Analysis for a Sample of G-type Main Sequence Kepler Targets

    NASA Astrophysics Data System (ADS)

    Mehrabi, Ahmad; He, Han; Khosroshahi, Habib

    2017-01-01

    The variation of a stellar light curve owing to rotational modulation by magnetic features (starspots and faculae) on the star’s surface can be used to investigate the magnetic properties of the host star. In this paper, we use the periodicity and magnitude of the light-curve variation as two proxies to study the stellar magnetic properties for a large sample of G-type main sequence Kepler targets, for which the rotation periods were recently determined. By analyzing the correlation between the two magnetic proxies, it is found that: (1) the two proxies are positively correlated for most of the stars in our sample, and the percentages of negative, zero, and positive correlations are 4.27%, 6.81%, and 88.91%, respectively; (2) negative correlation stars cannot have a large magnitude of light-curve variation; and (3) with the increase of rotation period, the relative number of positive correlation stars decreases and the negative correlation one increases. These results indicate that stars with shorter rotation period tend to have positive correlation between the two proxies, and a good portion of the positive correlation stars have a larger magnitude of light-curve variation (and hence more intense magnetic activities) than negative correlation stars.

  19. AgRuO3 , a Strongly Exchange-Coupled Honeycomb Compound Lacking Long-Range Magnetic Order.

    PubMed

    Prasad, Beluvalli E; Kanungo, Sudipta; Jansen, Martin; Komarek, Alexander C; Yan, Binghai; Manuel, Pascal; Felser, Claudia

    2017-04-03

    Quasi two-dimensional (2D) oxide-based honeycomb lattices have attracted great attention for displaying specific electronic instabilities, which give rise to unconventional bonding patterns and unexpected magnetic exchange couplings. The synthesis of AgRuO3 , another representative exhibiting unique structural properties, is reported here. The stacking sequence of the honeycomb layers (Ru2 O6 ) differs from analogous precedents; in particular, the intercalating silver atoms are shifted from the middle of the interspaces and cap the void octahedral sites of the (□Ru2 O6 ) slabs from both sides. This way, charge neutral, giant 2D "molecules" of Ag/Ru2 O6 /Ag result; a feature that significantly enhances the overall 2D character of AgRuO3 . Measurements of magnetization have revealed extremely strong magnetic exchange coupling to be present, surviving to a temperature as high as 673 K, which is the temperature of thermal decomposition. No indication for long-range magnetic order has, however, been observed. Theoretical analyses confirm the pronounced 2D character of the electronic system, and in particular reveal the inter-honeycomb layer coupling Jc to be distinctly weak.

  20. Facile synthesis of bimetallic Ag/Ni core/sheath nanowires and their magnetic and electrical properties.

    PubMed

    McKiernan, Maureen; Zeng, Jie; Ferdous, Sunzida; Verhaverbeke, Steven; Leschkies, Kurtis S; Gouk, Roman; Lazik, Christopher; Jin, Miao; Briseno, Alejandro L; Xia, Younan

    2010-09-06

    This paper describes a facile method for coating Ag nanowires with uniform, ferromagnetic sheaths made of polycrystalline Ni. A typical sample of these core/sheath nanowires had a saturation magnetization around 33 emu g(-1). We also demonstrated the use of this magnetic property to align the nanowires by simply placing a suspension of the nanowires on a substrate in a magnetic field and allowing the solvent to evaporate. The electrical conductivity of these core/sheath nanowires (2 × 10(3) S cm(-1)) was two orders of magnitude lower than that of bulk Ag (6.3 × 10(5) S cm(-1)) and Ni (1.4 × 10(5) S cm(-1)). This is likely caused by the transfer of electrons from the Ag core to the Ni sheath due to the difference in work function between the two metals. The electrons are expected to experience an increased resistance due to spin-dependent scattering caused by the randomized magnetic domains in the polycrystalline, ferromagnetic Ni sheath. Studies on the structural changes to the Ni coating over time under different storage conditions show that storage of the nanowires on a substrate under ambient conditions leads to very little Ni oxidation after 6 months. These Ag/Ni core/sheath nanowires show promise in areas such as electronics, spintronics, and displays.

  1. Fabrication of Gamma Detectors Based on Magnetic Ag:Er Microcalorimeters

    SciTech Connect

    Friedrich, Stephan; Boyd, Stephen; Cantor, Robin

    2016-05-06

    This report discusses the photolithographic fabrication of ultra-high resolution gamma-ray detectors based on magnetic microcalorimeters (MMCs). The MMC uses a novel Er-doped silver sensor (Ag:Er) that is expected to have higher sensitivity than the Er-doped gold (Au:Er) sensors currently in use. The MMC also integrates the first-stage SQUID preamplifier on the same chip as the MMC gamma detector to increase its signal-to-noise ratio. In addition, the MMC uses a passive Ta-Nb heat switch to replace one of the common long-term failure points in earlier detectors. This report discusses the fabrication process we have developed to implement the proposed improvements.

  2. Fabrication of Gamma Detectors Based on Magnetic Ag:Er Microcalorimeters

    SciTech Connect

    Friedrich, Stephan; Boyd, Stephen; Cantor, Robin

    2015-11-25

    This report discusses the photolithographic fabrication of ultra-high resolution gamma-ray detectors based on magnetic microcalorimeters (MMCs). The MMC uses a novel Er-doped silver sensor (Ag:Er) that is expected to have higher sensitivity than the Er-doped gold (Au:Er) sensors currently in use. The MMC also integrates the first-stage SQUID preamplifier on the same chip as the MMC gamma detector to increase its signal-to-noise ratio. In addition, the MMC uses a passive Ta-Nb heat switch to replace one of the common long-term failure points in earlier detectors. This report discusses the fabrication process we have developed to implement the proposed improvements.

  3. Main-Sequence CMEs as Magnetic Explosions: Compatibility with Observed Kinematics

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Sterling, Alphonse

    2004-01-01

    We examine the kinematics of 26 CMEs of the morphological main sequence of CMEs, those having the classic three-part bubble structure of (1) a bright front eveloping (2) a dark cavity within which rides (3) a bright blob/filamentary feature. Each CME is observed in Yohkoh/SXT images to originate from near the limb (> or equal to 0.7 R(sub Sun) from disk center). The basic data (from the SOHO LASCO CME Catalog) for the kinematics of each CME are the sequence of LASCO images of the CME, the time of each image, the measured radial distance of the front edge of the CME in each image, and the measured angular extent of the CME. About half of our CMEs (12) occur with a flare, and the rest (14) occur without a flare. While the average linear-fit speed of the flare CMEs (1000 km/s) is twice that of the non-flare CMEs (510 km/s), the flare CMEs and the non-flare CMEs are similar in that some have nearly flat velocity-height (radial extent) profiles (little acceleration), some have noticeably falling velocity profiles (noticeable deceleration), and the rest have velocity profiles that rise considerably through the outer corona (blatant acceleration). This suggests that in addition to sharing similar morphology, main-sequence CMEs all have basically the same driving mechanism. The observed radial progression of each of our 26 CMEs is fit by a simple model magnetic plasmoid that is in pressure balance with the radial magnetic field in the outer corona and that propels itself outward by magnetic expansion, doing no net work on its surroundings. On average over the 26 CMEs, this model fits the observations as well as the assumption of constant acceleration. This is compatible with main-sequence CMEs being magnetically driven, basically magnetic explosions, with the velocity profile in the outer corona being largely dictated by the initial Alfien speed in the CME (when the front is at approx. 3 (sub Sun), analogous to the mass of a main-sequence star dictating the luminosity.

  4. Booster main magnet power supply, present operation and potential future upgrades

    SciTech Connect

    Bajon, E.; Bannon, M.; Marneris, I.; Danowski, G.; Sandberg, J.; Savatteri, S.

    2011-03-28

    The Brookhaven Booster Main Magnet Power Supply (MMPS) is a 24 pulse thyristor control supply, rated at 5500 Amps, +/-2000 Volts, or 3000 Amps, +/-6000 Volts. The power supply is fed directly from the power utility and the peak magnet power is 18 MWatts. This peak power is seen directly at the incoming ac line. This power supply has been in operation for the last 18 years. This paper will describe the present topology and operation of the power supply, the feedback control system and the different modes of operation of the power supply. Since the power supply has been in operation for the last 18 years, upgrading this power supply is essential. A new power supply topology has been studied where energy is stored in capacitor banks. DC to DC converters are used to convert the dc voltage stored in the capacitor banks to pulsed DC voltage into the magnet load. This enables the average incoming power from the ac line to be constant while the peak magnet power is pulsed to +/- 18 MWatts. Simulations and waveforms of this power supply will be presented.

  5. Solid state synthesis of Mn5Ge3 in Ge/Ag/Mn trilayers: Structural and magnetic studies

    NASA Astrophysics Data System (ADS)

    Myagkov, V. G.; Bykova, L. E.; Matsynin, A. A.; Volochaev, M. N.; Zhigalov, V. S.; Tambasov, I. A.; Mikhlin, Yu L.; Velikanov, D. A.; Bondarenko, G. N.

    2017-02-01

    The thin-film solid-state reaction between elemental Ge and Mn across chemically inert Ag layers with thicknesses of (0, 0.3, 1 and 2.2 μm) in Ge/Ag/Mn trilayers was studied for the first time. The initial samples were annealed at temperatures between 50 and 500 °C at 50 °C intervals for 1 h. The initiation temperature of the reaction for Ge/Mn (without a Ag barrier layer) was 120 °C and increased slightly up to 250 °C when the Ag barrier layer thickness increased up to 2.2 μm. In spite of the Ag layer, only the ferromagnetic Mn5Ge3 compound and the Nowotny phase were observed in the initial stage of the reaction after annealing at 500 °C. The cross-sectional studies show that during Mn5Ge3 formation the Ge is the sole diffusing species. The magnetic and cross-sectional transmission electron microscopy (TEM) studies show an almost complete transfer of Ge atoms from the Ge film, via a 2.2 μm Ag barrier layer, into the Mn layer. We attribute the driving force of the long-range transfer to the long-range chemical interactions between reacting Mn and Ge atoms.

  6. The MAIN Shirt: A Textile-Integrated Magnetic Induction Sensor Array

    PubMed Central

    Teichmann, Daniel; Kuhn, Andreas; Leonhardt, Steffen; Walter, Marian

    2014-01-01

    A system is presented for long-term monitoring of respiration and pulse. It comprises four non-contact sensors based on magnetic eddy current induction that are textile-integrated into a shirt. The sensors are technically characterized by laboratory experiments that investigate the sensitivity and measuring depth, as well as the mutual interaction between adjacent pairs of sensors. The ability of the device to monitor respiration and pulse is demonstrated by measurements in healthy volunteers. The proposed system (called the MAIN (magnetic induction) Shirt) does not need electrodes or any other skin contact. It is wearable, unobtrusive and can easily be integrated into an individual's daily routine. Therefore, the system appears to be a suitable option for long-term monitoring in a domestic environment or any other unsupervised telemonitoring scenario. PMID:24412900

  7. Magnetic properties and magnetocaloric effect at room temperature of Ni50- x Ag x Mn37Sn13 alloys

    NASA Astrophysics Data System (ADS)

    Thanh, Tran Dang; Mai, Nguyen Thi; Dan, Nguyen Huy; Phan, The-Long; Yu, Seong-Cho

    2014-11-01

    In this work, we present a detailed study of the magnetic properties and the magnetocaloric effect at room temperature of Ni50- x Ag x Mn37Sn13 alloys with x = 1, 2, and 4, which were prepared by using an arc-melting method. Experimental results reveal that a partial replacement of Ag for Ni leads to a decrease in the anti-FM phase in the alloys. In addition, the martensitic-austenitic phase transition shifts towards lower temperature and is broaded. The Curie temperature ( T C A ) for the austenitic phase also shifts toward to lower temperature, but not by much. The Curie temperature was found to be 308, 305, and 298 K for x = 1, 2, and 4, respectively. The magnetic entropy change (Δ S m ) of the samples was calculated by using isothermal magnetization data. Under an applied magnetic field change of 10 kOe, the maximum value of Δ S m (|Δ S max |) was achieved at around room temperature and did not change much (~0.8 J·kg-1·K-1) with increasing Ag-doping concentration. Particularly, the M 2 vs. H/ M curves prove that all the samples exhibited a second-order magnetic phase transition. Based on Landau's phase-transition theory and careful analyses of the magnetic data around the T C A , we have determined the critical parameters β, γ, δ, and T C . The results show that the β values are located between those expected for the 3D-Heisenberg model ( β = 0.365) and mean-field theory ( β = 0.5). Such a result proves the coexistence of short-range and long-range ferromagnetic interactions in Ni50- x Ag x Mn37Sn13 alloys. The nature of the changes in the critical parameters and the |Δ S max | is thoroughly discussed by means of structural analyses.

  8. The main injector chromaticity correction sextupole magnets: Measurements and operating schemes

    SciTech Connect

    Bhat, C.M.; Bogacz, A.; Brown, B.C.; Harding, D.J.; Fang, S.J.; Martin, P.S.; Glass, H.D.; Sim, J.

    1995-05-01

    The Fermilab Main Injector (FMI) is a high intensity proton synchrotron which will be used to accelerate protons and antiprotons from 8.9 GeV/c to 150 GeV/c. The natural chromaticities of the machine for the horizontal and the vertical Planes are {minus}33.6 and {minus}33.9 respectively. The {Delta}p/p of the beam at injection is about 0.002. The chromaticity requirements of the FMI, are primarily decided by the {Delta}p/p = 0.002 of the beam at injection. This limits the final chromaticity of the FMI to be {plus_minus}5 units. To correct the chromaticity in the FMI two families of sextupole magnets will be installed in the lattice, one for each plane. A sextupole magnet suitable for the FMI needs has been designed and a number of them are being built. New chromaticity compensation schemes have been worked out in the light of recently proposed faster acceleration ramps. On an R/D sextupole magnet the low current measurements have been carried out to determine the electrical properties. Also, using a Morgan coil, measurements have been performed to determine the higher ordered multipole components up to 18-poles. An overview of these result are presented here.

  9. Synthesis and characterization of magnetically recyclable Ag nanoparticles immobilized on Fe3O4@C nanospheres with catalytic activity

    NASA Astrophysics Data System (ADS)

    Li, Wei-hong; Yue, Xiu-ping; Guo, Chang-sheng; Lv, Jia-pei; Liu, Si-si; Zhang, Yuan; Xu, Jian

    2015-04-01

    A novel approach for the synthesis of Ag-loaded Fe3O4@C nanospheres (Ag-Fe3O4@C) was successfully developed. The catalysts possessed a carbon-coated magnetic core and grew active silver nanoparticles on the outer shell using hydrazine monohydrate as the AgNO3 reductant in ethanol. The morphology, inner structure, and magnetic properties of the as-prepared composites were studied with transmission electron microscopy (TEM), X-ray powder diffraction (XRD), fourier translation infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. Catalytic activity was investigated by degrading rhodamine B (RhB) in the designed experiment. The obtained products were monodispersed and bifunctional with high magnetization, as well as exhibited excellent catalytic activity toward organic dye with 98% of RhB conversion within 20 min in the presence of NaBH4. The product also exhibited convenient magnetic separability and maintained high catalytic activity after six cycle runs.

  10. Magnetically Separable Fe3O4/AgBr Hybrid Materials: Highly Efficient Photocatalytic Activity and Good Stability

    NASA Astrophysics Data System (ADS)

    Cao, Yuhui; Li, Chen; Li, Junli; Li, Qiuye; Yang, Jianjun

    2015-06-01

    Magnetically separable Fe3O4/AgBr hybrid materials with highly efficient photocatalytic activity were prepared by the precipitation method. All of them exhibited much higher photocatalytic activity than the pure AgBr in photodegradation of methyl orange (MO) under visible light irradiation. When the loading amount of Fe3O4 was 0.5 %, the hybrid materials displayed the highest photocatalytic activity, and the degradation yield of MO reached 85 % within 12 min. Silver halide often suffers serious photo-corrosion, while the stability of the Fe3O4/AgBr hybrid materials improved apparently than the pure AgBr. Furthermore, depositing Fe3O4 onto the surface of AgBr could facilitate the electron transfer and thereby leading to the elevated photocatalytic activity. The morphology, phase structure, and optical properties of the composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse reflectance spectra (UV-vis DRS), and photoluminescence (PL) techniques.

  11. Tri-functional Fe2O3-encased Ag-doped ZnO nanoframework: magnetically retrievable antimicrobial photocatalyst

    NASA Astrophysics Data System (ADS)

    Karunakaran, Chockalingam; Vinayagamoorthy, Pazhamalai

    2016-11-01

    Fe2O3-encased ZnO nanoframework was obtained by hydrothermal method and was doped with Ag through photoreduction process. Energy dispersive x-ray spectroscopy, transmission electron microscopy (TEM), high resolution TEM, selected area electron diffractometry, x-ray diffractometry and Raman spectroscopy were employed for the structural characterization of the synthesized material. While the charge transfer resistance of the prepared nanomaterial is larger than those of Fe2O3 and ZnO the coercivity of the nanocomposite is less than that of hydrothermally obtained Fe2O3 nanostructures. Although Fe2O3/Ag-ZnO exhibits weak visible light absorption its band gap energy does not differ from that of ZnO. The photoluminescence of the fabricated nanoframework is similar to that of ZnO. The radiative recombination of charge carriers is slightly slower in Fe2O3/Ag-ZnO than in ZnO. The synthesized Fe2O3-encased Ag-doped ZnO, under UV A light, exhibits sustainable photocatalytic activity to degrade dye and is magnetically recoverable. Also, the Fe2O3/Ag-ZnO nanocomposite disinfects bacteria effectively in absence of direct illumination.

  12. Incommensurate magnetic order in Ag2NiO2 studied with muon-spin-rotation and relaxation spectroscopy

    NASA Astrophysics Data System (ADS)

    Sugiyama, J.; Ikedo, Y.; Mukai, K.; Brewer, J. H.; Ansaldo, E. J.; Morris, G. D.; Chow, K. H.; Yoshida, H.; Hiroi, Z.

    2006-06-01

    The nature of the magnetic transition of the half-filled triangular antiferromagnet Ag2NiO2 with TN=56K was studied with positive muon-spin-rotation and relaxation (μ+SR) spectroscopy. Zero field μ+SR measurements indicate the existence of a static internal magnetic field at temperatures below TN . Two components with slightly different precession frequencies and wide internal-field distributions suggest the formation of an incommensurate antiferromagnetic order below 56K . This implies that the antiferromagnetic interaction is predominant in the NiO2 plane in contrast to the case of the related compound NaNiO2 . An additional transition was found at ˜22K by both μ+SR and susceptibility measurements. It was also clarified that the transition at ˜260K observed in the susceptibility of Ag2NiO2 is induced by a purely structural transition.

  13. Comparison Of The Global Analytic Models Of The Main Geomagnetic Field With The Stratospheric Balloon Magnetic Data 335

    NASA Astrophysics Data System (ADS)

    Tsvetkov, Yu.; Filippov, S.; Frunze, A.

    2013-12-01

    Three global analytical models of a main geomagnetic field constructed by satellite data are used: model IGRF, Daily Mean Spherical Harmonic Models (DMSHM), and model EMM/2010, and also scalar data of geomagnetic field and its gradients, received in stratospheric balloon gradient magnetic surveys at altitudes of ~30 km. At these altitudes the regional magnetic field is formed from all sources of the Earth's crust. It enables to receive along lengthy routes of surveys the fullest data on regional and longwave-lenght magnetic anomalies. Model DMSHM is used at extracting of magnetic anomalies for elimination of a secular variation up to significant value 0,2 nT. The model can be constructed within the limits of ± 1 months from the moment stratospheric balloon surveys with beneficial day terms with magnetic activity up to Kp <20, that leads to an error of representation of main MFE equal ±5 нТл. It is possible at presence acting for the period of stratospheric balloon magnetic survey of the satellite, for example, Swarm. On stratospheric balloon data it is shown, that model EMM/2010 unsatisfactorily displays MFE at altitude of 30 km. Hence, the qualitative model of the constant (main and anomaly) magnetic field cannot be constructed only with use of satellite and ground data. The improved model constant MFE, constructed according to satellite and stratospheric balloon magnetic surveys, developed up to a degree and the order m=n=720, will have a reliable data about regional crust magnetic field, hence, and about deep magnetic structure of the Earth's crust. The use gradient magnetic surveys aboard stratospheric balloons allows to find the places alternating approximately through 3000 km in which there are no magnetic anomalies. In these places probably to supervise satellite magnetic models for a range of altitude of 20-40 km, timed to stratospheric balloon magnetic surveys.

  14. Synthesis, characterization, and application of Fe3O4/Ag magnetic composites for mercury removal from water

    NASA Astrophysics Data System (ADS)

    Elhouderi, Z. A.; Beesley, D. P.; Nguyen, T. T.; Lai, P.; Sheehan, K.; Trudel, S.; Prenner, E.; Cramb, D. T.; Anikovskiy, M.

    2016-04-01

    Engineered nanocomposites (NCs) have recently emerged as materials of great scientific and technological interest. In these materials, different components are combined to yield a nanoentity with desired properties not afforded by the constituent materials. Designing novel NCs and synthetic routes that enable controlling the size and functionalities remains an active area of research. Here, we present a two-step method of synthesizing Ag-Fe3O4 NCs with tunable sizes. Unlike previously reported structures, the prepared NCs do not have a familiar core-shell architecture. Instead, small Fe3O4 nanoparticles (NPs) are embedded in a larger silver matrix. The superparamagnetic Fe3O4 NPs endow the NC with magnetic properties, enabling easy separation from solution. The degree of the NC response to an external magnetic field can be controlled by varying the concentration of Fe3O4 NPs during the synthesis. The Ag matrix serves to protect the embedded Fe3O4 NPs from degradation and can be used for further functionalization of the NCs with different sulfhydryl containing linkers. To demonstrate utility, we show how decorating the outer layer of the Ag NC with diphenyl-4,4‧-dithiol transforms the NCs into a water purifying system capable of sequestering highly toxic Hg2+ ions from solution magnetically.

  15. Charge transport in superionic and melted AgI under a magnetic field studied via molecular dynamics

    NASA Astrophysics Data System (ADS)

    Gagliardi, Luca; Bonella, Sara

    2016-10-01

    Charge transport in AgI subject to an external magnetic field is studied via computer simulations. We demonstrate that a recently developed algorithm can effectively complement problematic experiments to detect the ionic Hall effect, and identify previously unreported effects such as ionic magnetoresistance. We focus first on the charge transport properties of superionic AgI, showing that the magnetic field induces a considerable reduction in the diagonal elements of the conductivity tensor (magnetoresistance). Within the limits of the signal-to-noise ratio, calculation of the off-diagonal elements of this tensor also shows the onset of the Hall effect in this material. We then present numerical evidence supporting the use of the Nerst-Einstein approximation to obtain the Hall mobility of the system. This approximation enables very efficient detection of the Hall signal, with values of the mobility and of the migration activation energy in very good agreement with experiments. Having validated our simulation approach, we consider melted AgI to investigate if the Hall signal persists in this nonsuperionic case, finding a detectable signal. Comparison of the diffusion tensor of this system with that of molten NaCl also indicates why the Hall signal is absent in the latter. This work paves the way for the routine use of simulations to study transport, and in particular the ionic Hall effect, in ionic systems under external magnetic field.

  16. Spectral anion sensing and γ-radiation induced magnetic modifications of polyphenol generated Ag-nanoparticles

    NASA Astrophysics Data System (ADS)

    Ansari, Zarina; Dhara, Susmita; Bandyopadhyay, Bilwadal; Saha, Abhijit; Sen, Kamalika

    2016-03-01

    A fast one step bio-synthesis for in situ preparation of silver nanoparticles is proposed. The method involves reduction of AgNO3 with an aqueous extract of peanut skin, which is a good source of polyphenols. The silver nanoparticles thus synthesized were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis absorption spectroscopy, Fourier Transform infrared (FTIR) spectroscopy and magnetic measurements. Effect of low dose γ irradiation during the synthesis was studied and their physico-chemical properties were compared with those produced without irradiation. On the contrary to the diamagnetic behavior of bulk silver, the silver nanoparticles thus prepared show a significant ferromagnetic moment component. Variable time exposure to γ-irradiation results in an exponential decay of ferromagnetic component. A freshly prepared solution of silver nanoparticles shows selective spectral changes towards iodide ions at trace concentration (below 50 μM) among a series of 16 other competing anions. The prepared nanoparticles are therefore suitable for anion sensing application.

  17. Spectral anion sensing and γ-radiation induced magnetic modifications of polyphenol generated Ag-nanoparticles.

    PubMed

    Ansari, Zarina; Dhara, Susmita; Bandyopadhyay, Bilwadal; Saha, Abhijit; Sen, Kamalika

    2016-03-05

    A fast one step bio-synthesis for in situ preparation of silver nanoparticles is proposed. The method involves reduction of AgNO3 with an aqueous extract of peanut skin, which is a good source of polyphenols. The silver nanoparticles thus synthesized were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis absorption spectroscopy, Fourier Transform infrared (FTIR) spectroscopy and magnetic measurements. Effect of low dose γ irradiation during the synthesis was studied and their physico-chemical properties were compared with those produced without irradiation. On the contrary to the diamagnetic behavior of bulk silver, the silver nanoparticles thus prepared show a significant ferromagnetic moment component. Variable time exposure to γ-irradiation results in an exponential decay of ferromagnetic component. A freshly prepared solution of silver nanoparticles shows selective spectral changes towards iodide ions at trace concentration (below 50 μM) among a series of 16 other competing anions. The prepared nanoparticles are therefore suitable for anion sensing application.

  18. One-pot sequential synthesis of magnetically separable Fe3O4/AgCl photocatalysts with enhanced activity and stability

    NASA Astrophysics Data System (ADS)

    Liu, Zening; Liu, Yongcheng; Cai, Mujin; Xu, Piaopiao; Ma, Zonghua; Yuan, Hong

    2017-03-01

    Magnetically separable Fe3O4/AgCl photocatalysts were prepared by a one-pot sequential method. A series of techniques proved the hybrid structure of Fe3O4/AgCl composites. Fe3O4/AgCl composites had a much higher photocatalytic activity toward Rhodamine B (RhB) degradation than pure AgCl under the simulated solar light irradiation. The existence of metal Ag resulted in high photocatalytic activity of Fe3O4/AgCl, which was related with the amount of metallic Ag. The scavenging experiments showed that the degradation reaction most probably was initiated by the photoinduced single-electron transfer, and the generation of superoxide anion (O 2 -· ) played a significant role. The composite photocatalysts could be recycled by applying an external magnetic field, and the reused composites maintained their original photocatalytic activity. Fe3O4/AgCl composites were highly efficient, magnetically separable, and recoverable. This proves their potential applications in the photodegradation of organic pollutants.

  19. Optimization of Fe3O4@Ag nanoshells in magnetic field-enriched surface-enhanced resonance Raman scattering for malaria diagnosis.

    PubMed

    Yuen, Clement; Liu, Quan

    2013-11-07

    The great potential of magnetic field enriched surface enhanced resonance Raman spectroscopy (SERRS) for early malaria diagnosis has been demonstrated previously. This technique is able to detect β-hematin, which is equivalent to a malaria biomarker (hemozoin) in Raman features, at a concentration of 5 nM. In this study, we present the optimization of nanoparticles used in the magnetic field enriched SERRS by tuning the core size and shell thickness of nanoparticles with an iron oxide core and a silver shell (Fe3O4@Ag). The discrete dipole approximation (DDA) model was introduced to investigate the localized electromagnetic field distributions and extinction efficiencies of the aggregate of Fe3O4@Ag and β-hematin, in correlation with their magnetic field enriched SERRS performance. We find that the optimal core-shell size of Fe3O4@Ag leading to the effective aggregation of Fe3O4@Ag and β-hematin under an external magnetic field with superior extinction efficiencies is the key to realize highly augmented Raman signals in this strategy. Furthermore, it is noted that the optimized result differs from the case without the external magnetic field to that with the external magnetic field. Therefore, this work demonstrates experimentally and theoretically the potential of tuning the core-shell Fe3O4@Ag for achieving the efficient magnetic field-enriched SERRS detection of β-hematin for early malaria diagnosis.

  20. Ag/SiO2 core-shell nanoparticle-based surface-enhanced Raman probes for immunoassay of cancer marker using silica-coated magnetic nanoparticles as separation tools.

    PubMed

    Gong, Ji-Lai; Liang, Yi; Huang, Yong; Chen, Ji-Wei; Jiang, Jian-Hui; Shen, Guo-Li; Yu, Ru-Qin

    2007-02-15

    A simple, sensitive and highly specific immunoassay has been developed based on surface-enhanced Raman scattering for human alpha-fetoprotein (AFP), a tumor marker for the diagnosis of hepatocellular carcinoma. This strategy combines the Ag/SiO2 core-shell nanoparticles embedded with rhodamine B isothiocyanate dye molecules as Raman tags and the amino group modified silica-coated magnetic nanoparticle as immobilization matrix and separation tool. In the proposed system, a sandwich-type immunoassay was performed between polyclonal antibody functionalized Ag/SiO2 nanoparticle-based Raman tags and monoclonal antibody modified silica-coated magnetic nanoparticles. The presence of the analyte and the reaction between the antigen and antibody can be monitored by the Raman spectra of the Ag/SiO2 tags. Compared to the previous surface-enhanced Raman immunoassays, the main advantage of this strategy lies in two aspects. One is the high stability of Raman tags derived from the silica shell-coated silver core-shell nanostructure. The other is the use of silica-coated magnetic nanoparticles as immobilization matrix and separation tool, thus avoiding complicated pretreatment and washing steps. We have studied in detail the experimental parameters such as the effects of the antibody concentration modified on the Raman tags and on the magnetic particles, and the immunoreaction time. Using this strategy, concentration of human AFP up to 0.12 microg/ml was detected with a detection limit of 11.5 pg/ml.

  1. HSX: Engineering Design and Fabrication of the main Magnet Coils, Vacuum Vessel and Support/Alignment Structure

    NASA Astrophysics Data System (ADS)

    Anderson, F. Simon B.; Anderson, D. T.; Almagri, A. F.; Matthews, P. G.; Probert, P. H.; Shohet, J. L.; Talmadge, J. N.

    1996-11-01

    The HSX device, with a magnetic field consisting of a SINGLE dominant HELICAL component, has a set of 48 twisted main magnetic field coils. Engineering analysis (ANSYS) has resulted in a set of construction and alignment constraints and goals for field accuracy and coil structural strength. Close proximity of the main coil set to the magnetic separatrix imposes space restrictions on the vacuum vessel. Fabrication of the vessel using explosive techniques, and the structural analysis for the stresses in the vacuum chamber will be discussed. Crucial to the integrity of the quasihelical magnetic field is the accurate positioning of the magnet coils and maintenance of the position during operation. The design and construct- ion of the completed support structure for HSX coils will also be presented. *** Work supported by U.S Dept. of Energy Grant DE-FG02-93ER54222

  2. Non-contact main cable NDE technique for suspension bridge using magnetic flux-based B-H loop measurements

    NASA Astrophysics Data System (ADS)

    Park, Seunghee; Kim, Ju-Won; Moon, Dae-Joong

    2015-04-01

    In this study, a noncontact main cable NDE method has been developed. This cable NDE method utilizes the direct current (DC) magnetization and a searching coil-based total flux measurement. A total flux sensor head prototype was fabricated that consists of an electro-magnet yoke and a searching coil sensor. To obtain a B-H loop, a magnetic field was generated by applying a cycle of low frequency direct current to the electro-magnet yoke. During the magnetization, a search coil sensor measures the electromotive force from magnetized cable. During the magnetization process, a search coil sensor was measured the magnetic flux density. Total flux was calculated by integrating the measured magnetic flux using a fluxmeter. A B-H loop is obtained by using relationship between a cycle of input DC voltage and measured total flux. The B-H loop can reflect the property of the ferromagnetic materials. Therefore, the cross-sectional loss of cable can be detected using variation of features from the B-H curve. To verify the feasibility of the proposed steel cable NDE method, a series of experimental studies using a main-cable mock-up specimen has been performed in this study.

  3. Structural and magnetic phase transitions in CeCu6-xTx (T = Ag,Pd)

    DOE PAGES

    Poudel, Lekhanath N.; De la cruz, Clarina; Payzant, E. Andrew; ...

    2015-12-15

    The structural and the magnetic properties of CeCu6-xAgx (0 ≤ x ≤ 0.85) and CeCu6-xPdx (0 ≤ x ≤ 0.4) have been studied using neutron diffraction, resonant ultrasound spectroscopy (RUS), x-ray diffraction measurements, and first principles calculations. The structural and magnetic phase diagrams of CeCu6-xAgx and CeCu6-xPdx as a function of Ag/Pd composition are reported. The end member, CeCu6, undergoes a structural phase transition from an orthorhombic (Pnma) to a monoclinic (P21/c) phase at 240 K. In CeCu6-xAgx, the structural phase transition temperature (Ts) decreases linearly with Ag concentration and extrapolates to zero at xS ≈ 0.1. The structural transitionmore » in CeCu6-xPdx remains unperturbed with Pd substitution within the range of our study. The lattice constant b slightly decreases with Ag/Pd doping, whereas a and c increase with an overall increase in the unit cell volume. Both systems, CeCu6-xAgx and CeCu6-xPdx, exhibit a magnetic quantum critical point (QCP), at x ≈ 0.2 and x ≈ 0.05, respectively. Near the QCP, long range antiferromagnetic ordering takes place at an incommensurate wave vector (δ1 0 δ2), where δ1 ~ 0.62, δ2 ~ 0.25, x = 0.125 for CeCu6-xPdx and δ1 ~ 0.64, δ2 ~ 0.3, x = 0.3 for CeCu6-xAgx. As a result, the magnetic structure consists of an amplitude modulation of the Ce moments which are aligned along the c axis of the orthorhombic unit cell.« less

  4. Environmentally friendly electroless plating for Ag/TiO2-coated core-shell magnetic particles using ultrasonic treatment.

    PubMed

    Kim, Soo-Dong; Choe, Won-Gyun; Jeong, Jong-Ryul

    2013-11-01

    In this work, high-reflectance brilliant white color magnetic microspheres comprising a Fe/TiO2/Ag core-shell structure with a continuous, uniform compact silver layer were successfully fabricated by TiO2-assisted electroless plating in a simple and eco-friendly method. The coating procedure for TiO2 and Ag involved a sol-gel reaction and electroless plating with ultrasound treatment. The electroless plating step was carried out in an eco-friendly manner in a single process without environmentally toxic additives. The TiO2 layer was used as a modification layer between the Fe microspheres and the silver layer to improve adhesion. A continuous and compact silver layer could be formed with a high degree of morphological control by introducing ultrasonication and adjusting the ammonium hydroxide concentration.

  5. Synthesis and electro-magnetic properties of flower-like Fe2O3-Ag nanocomposite using direct subsidence loading method

    NASA Astrophysics Data System (ADS)

    Zhou, Xing; Wu, Zhengying; Xu, Nan; Liu, Shouqing; Zhao, Guizhe; Liu, Yaqing

    2015-10-01

    Novel flower-like Fe2O3/Ag nanocomposites were synthesized by a simple direct subsidence loading method. The composition and morphology of the obtained samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SEAD) techniques. The Ag nanoparticles which loaded on the surface of petals exhibit spherical morphology. Further, the magnetic and electrical conductive properties reveal the well controllable performance. Room temperature magnetic measurement of the flower-like nanocomposites demonstrated its ferromagnetic properties and the saturation magnetization (Ms) decreased from 0.6 to 0.11 emu/g.

  6. Sediment fingerprinting by using the Ag-110m: Cs-137 ratio along the main rivers draining the Fukushima radioactive pollution plume

    NASA Astrophysics Data System (ADS)

    Chartin, Caroline; Evrard, Olivier; Onda, Yuichi; Patin, Jeremy; Lefèvre, Irène; Ayrault, Sophie; Lepage, Hugo; Bonté, Philippe

    2013-04-01

    During the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, large quantities of radionuclides were released into the environment between 12 and 19 March 2011. Even though about 80% of these emissions were transported offshore and out over the Pacific Ocean, 20% were deposited as wet and dry deposits on soils of Fukushima Prefecture on 15-16 March. In particular, 6.4 PBq of Cs-137 were modeled to have deposited on Japanese soils over a distance of 70 km to the northwest of the Fukushima Dai-ichi nuclear power plant. As most radionuclides are strongly sorbed by fine particles, and their mineralogical clay and organic matter fractions, they are likely to be redistributed within the landscape in association with soil and sediment particles transported by erosion processes and runoff. Based on a spatial analysis of the gamma-emitting radionuclides present in the environment respectively eight and thirteen months after the accident, we aim to provide a radioactive tracer to investigate the temporal evolution of the contaminant dispersion across Fukushima Prefecture. For this purpose, sediments were collected along rivers draining the main contamination plume in Fukushima Prefecture (i.e, Rivers Kutchibuto, Mano, Nitta and Ota) in November 2011 and April 2012.These campaigns directly followed the main hydro-sedimentary events that occurred in this region, i.e., the typhoon season (July and September-October) and the snowmelt (March 2012). The river sediment activities in gamma-emitting radionuclides were then compared to the initial activities measured in soils provided by the Japanese Ministry of Education, Culture, Sport, Science and Technology (MEXT). The initial fallout patterns in 110mAg appeared to differ from those of the main contamination plume defined mainly by radiocaesium fallout (i.e., Cs-134+137). The Ag-110m:Cs-137 ratio was then used to trace the spatial origin of contaminated sediment collected in rivers. Sediments collected within the coastal

  7. A comparative study of the magnetic properties of the 1/1 approximant Ag(50)In(36)Gd(14) and the icosahedral quasicrystal Ag(50)In(36)Gd(14).

    PubMed

    Wang, P; Stadnik, Z M; Al-Qadi, K; Przewoźnik, J

    2009-10-28

    We report on measurements of the dc and ac magnetic susceptibility, (155)Gd Mössbauer spectra, and specific heat of the 1/1 approximant Ag(50)In(36)Gd(14), and of the ac magnetic susceptibility of the icosahedral quasicrystal Ag(50)In(36)Gd(14). These alloys are shown to be spin glasses. For the icosahedral quasicrystal Ag(50)In(36)Gd(14), spin freezing occurs at T(f) = 4.3 K, and the frequency dependence of T(f) is well accounted for by the Vogel-Fulcher and power laws. Spin freezing in the 1/1 approximant Ag(50)In(36)Gd(14) occurs in two stages: at T(f(1)) = 3.7 K, Gd spins develop short-range correlations but continue to fluctuate, and then long-range freezing is achieved at T(f(2)) = 2.4 K. The frequency dependences of T(f(1)) and T(f(2)) can be accounted for by means of the Vogel-Fulcher law and the critical slowing down dynamics. It is shown that the spin freezing in both alloys is a nonequilibrium phenomenon rather than a true equilibrium phase transition. The (155)Gd Mössbauer spectra of the 1/1 approximant Ag(50)In(36)Gd(14) confirm that the Gd spins are frozen at 1.5 K and are fluctuating at 4.6 K. The magnetic specific heat exhibits a maximum at a temperature that is 30% larger than T(f(1)), but the temperature derivative of the magnetic entropy peaks at T(f(1)). The Debye temperature of the 1/1 approximant Ag(50)In(36)Gd(14) is 199(1) K as determined from the Mössbauer data, and 205(2) K as determined from the specific heat data.

  8. Thermal conditions on the International Space Station: Heat flux and temperature investigation of main radiators for the Alpha Magnetic Spectrometer

    NASA Astrophysics Data System (ADS)

    Xie, Min; Gao, Jianmin; Wu, Shaohua; Qin, Yukun

    2016-09-01

    The investigation on heat flux can clarify the thermal condition and explain temperature behavior on the main radiators of the Alpha Magnetic Spectrometer (AMS). In this paper, a detailed investigation of heat flux on the AMS main radiators is proposed. The heat transfer process of the AMS main radiators is theoretically analyzed. An updated thermal model of the AMS on the International Space Station (ISS) is developed to calculate the external heat flux density on the AMS main radiators. We conclude the ISS components and operations affect on the solar flux density of the AMS main radiators by reflecting or shading solar illumination. According to the energy conservation on the AMS main radiators, the temperature variation mainly depends on the solar flux change. The investigations are conducive to reference for the long-duration thermal control of the AMS, and knowledge for the thermal conditions on the ISS.

  9. Neodymium as the main feature of permanent magnets from hard disk drives (HDDs).

    PubMed

    München, Daniel Dotto; Veit, Hugo Marcelo

    2017-03-01

    As a way to manage neodymium-iron-boron (NdFeB) magnets wasted in end-of-life hard disk drives (HDDs), a waste characterization is needed prior to a recycling process. Due to their magnetic properties, NdFeB magnets are essential in technological applications nowadays, thus causing an increase in the industrial demand for rare earth metals. However, these metals have a short supply, since they are difficult to obtain from ores, creating a critical market. In this work, a study of the characterization of sintered neodymium-iron-boron magnets was undertaken by qualitatively and quantitatively uncovering the neodymium recovery potential from this type of electronic waste. From the collection and disassembly of hard disk drives, in which the magnet represents less than 3% of the total weight, an efficient demagnetization process was proceeded at 320°C. Then, the magnet was ground and screened for an X-ray diffraction (XRD) analysis, which showed the Nd2Fe14B tetragonal phase as the dominant constituent of the sample. An analysis was also carried out in a scanning electron microscope (SEM) and an inductively coupled plasma optical emission spectrometer (ICP-OES), where the magnet composition showed 21.5wt% of neodymium and 65.1wt% of iron, among other chemicals. This Nd content is higher than the one found in Nd ores, enhancing the recyclability and the importance of waste management.

  10. Mirroring the dynamic magnetic behavior of magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates

    NASA Astrophysics Data System (ADS)

    Agra, K.; Gomes, R. R.; Della Pace, R. D.; Dorneles, L. S.; Bohn, F.; Corrêa, M. A.

    2015-11-01

    We investigate the magnetoimpedance effect in a wide frequency range in magnetostrictive Co/(Ag,Cu,Ta) multilayers grown onto rigid and flexible substrates. We observe a direct correlation between structural and quasi-static magnetic properties and the magnetoimpedance effect, since they are directly dependent on the nature of the spacer material. Moreover, we verify that all these properties are insensitive to the kind of employed substrate. We compare the magnetoimpedance results measured for multilayers in rigid and flexible substrates and discuss them in terms of different mechanisms that govern the impedances changes, magnetic anisotropy, structural character, and of numerical calculation results found in the literature. The fact that magnetostrictive multilayers can be reproduced in distinct kinds of substrates corresponds to an important advance for their applicability. The results place multilayers grown onto flexible substrates as attractive candidates for application as probe element in the development of MI-based sensor devices.

  11. Thermal conditions on the International Space Station: Effects of operations of the station Main Radiators on the Alpha Magnetic Spectrometer

    NASA Astrophysics Data System (ADS)

    Xie, Min; Burger, Joseph

    2016-04-01

    A thermal model of the Alpha Magnetic Spectrometer on the International Space Station (ISS) has been developed, and Thermal Desktop® (with RadCAD®) and SINDA/FLUINT software have been used to calculate the effects of the operations of the ISS Main Radiators on AMS temperatures. We find that the ISS Starboard Main Radiator has significant influence on temperatures on the port side of AMS. The simulation results are used in AMS thermal control operations.

  12. High frequency variations of the main magnetic field: convergence of observations and theory (Petrus Peregrinus Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Jault, Dominique

    2013-04-01

    Understanding the main magnetic field variations has been hindered by the discrepancy between the periods (from months to years) of the simplest linear wave phenomena and the relatively long time intervals (10 to 100 years) over which magnetic field changes can be confidently monitored. A theoretical description of short-period waves within the Earth's fluid core is at hand. Quasi-geostrophic inertial waves (akin to Rossby waves in the atmosphere) are slightly modified in the presence of magnetic fields and torsional oscillations consist of differential motion between coaxial rigid cylindrical annuli. Torsional oscillations are sensitive to the whole magnetic field that they shear in the course of their propagation. From their modelling, we have thus gained an estimate for the magnetic field strength in the core interior. There is now ongoing work to extend the theoretical framework to longer times. Furthermore, data collected from the Swarm constellation of three satellites to be launched this year by ESA will permit to better separate the internal and external magnetic signals. We may thus dream to detect quasi-geostrophic inertial waves. As the spectral ranges of theoretical models and observations begin to overlap, we can now go beyond the understanding of the magnetic field variations as the juxtaposition of partial models, arranged as a set of nested Matryoshka dolls. This talk will give illustrations for this statement, among which the question of induction in the lower mantle.

  13. Boosted Hyperthermia Therapy by Combined AC Magnetic and Photothermal Exposures in Ag/Fe3O4 Nanoflowers.

    PubMed

    Das, R; Rinaldi-Montes, N; Alonso, J; Amghouz, Z; Garaio, E; García, J A; Gorria, P; Blanco, J A; Phan, M H; Srikanth, H

    2016-09-28

    Over the past two decades, magnetic hyperthermia and photothermal therapy are becoming very promising supplementary techniques to well-established cancer treatments such as radiotherapy and chemotherapy. These techniques have dramatically improved their ability to perform controlled treatments, relying on the procedure of delivering nanoscale objects into targeted tumor tissues, which can release therapeutic killing doses of heat either upon AC magnetic field exposure or laser irradiation. Although an intense research effort has been made in recent years to study, separately, magnetic hyperthermia using iron oxide nanoparticles and photothermal therapy based on gold or silver plasmonic nanostructures, the full potential of combining both techniques has not yet been systematically explored. Here we present a proof-of-principle experiment showing that designing multifunctional silver/magnetite (Ag/Fe3O4) nanoflowers acting as dual hyperthermia agents is an efficient route for enhancing their heating ability or specific absorption rate (SAR). Interestingly, the SAR of the nanoflowers is increased by at least 1 order of magnitude under the application of both an external magnetic field of 200 Oe and simultaneous laser irradiation. Furthermore, our results show that the synergistic exploitation of the magnetic and photothermal properties of the nanoflowers reduces the magnetic field and laser intensities that would be required in the case that both external stimuli were applied separately. This constitutes a key step toward optimizing the hyperthermia therapy through a combined multifunctional magnetic and photothermal treatment and improving our understanding of the therapeutic process to specific applications that will entail coordinated efforts in physics, engineering, biology, and medicine.

  14. Results on search for a QGP with a TPC magnetic spectrometer at AGS and plans for an approx 4. pi. TPC magnetic spectrometer at RHIC

    SciTech Connect

    Lindenbaum, S.J. City Univ. of New York, NY )

    1991-01-01

    In the first part of this paper a search for a Quark-Gluon Plasma (QGP) with a TPC Magnetic Spectrometer at AGS by the BNL/CCNY/Johns Hopkins/Rice (E-810) Collaboration is discussed. At AGS energies the expected increase in baryon density is near maximum. If a QGP is formed even rarely this approach provides a sensitive method for its detection. We have found some interesting phenomena including strangeness enhancement, multi-{Lambda} and K{sub s}{sup 0} events and an increased slope for {pi}{sup {minus}} (corresponding to a reduced temperature) in the usual temperature plot for p{sub {perpendicular}} < 0.2 GeV/c. We plan to increase the statistics with the 14.5 GeV/c {times} A Si ions on targets from light to heavy and then to continue the program with incident Au ions. In Part 2 we discuss the BNL/CCNY/Notre Dame/Rice proposal for an {approx} 4{pi} TPC Magnetic Spectrometer for RHIC which we believe will be a sensitive probe for hadronic QGP signals, and also capable of observing departures from QCD should they occur. 8 refs., 12 figs.

  15. Variations in plasma parameters and magnetic field upon magnetopause crossing at the main phase maximum of the magnetic storm of November 14, 2012

    NASA Astrophysics Data System (ADS)

    Pulinets, M. S.; Kirpichev, I. P.; Antonova, E. E.

    2016-11-01

    Measurements of the plasma parameters and magnetic field upon magnetopause crossings by the THEMIS-A satellite during the large magnetic storm of November 14, 2012, are analyzed. The main specific feature of this event is the magnetopause crossing at the time of the magnetic-storm maximum. An imbalance of total pressure on the magnetopause reaching up to 40% has been observed. An abrupt turn of the magnetic field immediately on the magnetopause is recorded. Inside the magnetosphere, plasma motions have been observed, both along the magnetopause and inward, at velocities of 100-300 km/s. Variations in geomagnetic parameters are analyzed before and after the crossing. It is shown that specific features of the observed crossing may be associated with a sharp change in the magnetospheric current systems during the magnetospheric substorm.

  16. Investigation of magnetic field enriched surface enhanced resonance Raman scattering performance using Fe3O4@Ag nanoparticles for malaria diagnosis

    NASA Astrophysics Data System (ADS)

    Yuen, Clement; Liu, Quan

    2014-03-01

    Recently, we have demonstrated the magnetic field-enriched surface-enhanced resonance Raman spectroscopy (SERRS) of β-hematin by using nanoparticles with iron oxide core and silver shell (Fe3O4@Ag) for the potential application in the early malaria diagnosis. In this study, we investigate the dependence of the magnetic field-enriched SERRS performance of β-hematin on the different core and shell sizes of the Fe3O4@Ag nanoparticles. We note that the core and shell parameters are critical in the realization of the optimal magnetic field-enrich SERRS β-hematin signal. These results are consistent with our simulations that will guide the optimization of the magnetic SERRS performance for the potential early diagnosis in the malaria disease.

  17. First application of core-shell Ag@Ni magnetic nanocatalyst for transfer hydrogenation reactions of aromatic nitro and carbonyl compounds

    EPA Science Inventory

    A magnetic separable core-shell Ag@Ni nanocatalyst was prepared by a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as surfactant. The synthesized nanoparticles were characterized by several techniques such as X-ray diffr...

  18. First discovery of a magnetic field in a main-sequence δ Scuti star: the Kepler star HD 188774

    NASA Astrophysics Data System (ADS)

    Neiner, C.; Lampens, P.

    2015-11-01

    The Kepler space mission provided a wealth of δ Sct-γ Dor hybrid candidates. While some may be genuine hybrids, others might be misclassified due to the presence of a binary companion or to rotational modulation caused by magnetism and related surface inhomogeneities. In particular, the Kepler δ Sct-γ Dor hybrid candidate HD 188774 shows a few low frequencies in its light and radial velocity curves, whose origin is unclear. In this work, we check for the presence of a magnetic field in HD 188774. We obtained two spectropolarimetric measurements with an Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) at Canada-France-Hawaii Telescope. The data were analysed with the least-squares deconvolution (LSD) method. We detected a clear magnetic signature in the Stokes V LSD profiles. The origin of the low frequencies detected in HD 188774 is therefore most probably the rotational modulation of surface spots possibly related to the presence of a magnetic field. Consequently, HD 188774 is not a genuine hybrid δ Sct-γ Dor star, but the first known magnetic main-sequence δ Sct star. This makes it a prime target for future asteroseismic and spot modelling. This result casts new light on the interpretation of the Kepler results for other δ Sct-γ Dor hybrid candidates.

  19. Synthesis and properties of Ag-doped ZnO films with room temperature ferromagnetism

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Wang, Zhi-Jun; Chang, Ze-Jiang; Liu, Jing-Jin; Ren, Ya-Xuan; Sun, Hui-Yuan

    2016-12-01

    A series of Ag-doped ZnO films were prepared by DC magnetron sputtering. XRD and SEM results showed that the doping amount of Ag had a great influence on the films' morphology and ferromagnetism, and their magnetism can be improved by doping an appropriate amount of Ag. The theoretical analysis suggested that the magnetism resulted mainly from the film grain boundary surfaces. Further research revealed that these films had strong timeliness. Such a result indicated that the room temperature ferromagnetism of Ag-doped ZnO films did not stem from the cation vacancies but from the oxygen vacancies on the boundary surfaces.

  20. Ferromagnetic interactions between imino nitroxides through diamagnetic metal ions: Crystal structures, magnetism, and electronic properties of [M{sup I}(imino nitroxide){sub 2}](PF{sub 6}) (M = Cu{sup I} and Ag{sup I})

    SciTech Connect

    Oshio, Hiroki; Watanabe, Takashi; Ohto, Akihiro

    1997-07-02

    Ferromagnetic interactions between imino nitroxides through Diamagnetic Metal Ions: Crystal Structures, Magnetism, and Electronic Properties of [M{sup I}(imino nitroxide){sub 2}](PF{sub 6}) (M = Cu{sup I} and Ag{sup I}) Cu(I) and Ag(I) complexes with imino nitroxides, [Cu{sup I}-(immepy){sub 2}](PF{sub 6}) and [Ag{sup I}(impy){sub 2}](PF{sub 6}), were structurally and magnetically characterized. Magnetic susceptibility and EPR measurements revealed that the magnetic interaction in the Cu(I) complex is ferromagnetic with a J value of 55.1(6) cm{sup -1} (g = 2.0 and H = -JS{sub 1}{center_dot}S{sub 2}), while the Ag(I) complex shows a very weak ferromagnetic interaction. The magnetic behaviors were discussed in terms of orthogonality of magnetic orbitals and metal to ligand charge-transfer interactions.

  1. Architectural isomerism in the three-dimensional polymeric spin crossover system [Fe(pmd)2[Ag(CN)2]2]: synthesis, structure, magnetic properties, and calorimetric studies.

    PubMed

    Galet, Ana; Muñoz, M Carmen; Gaspar, Ana B; Real, José A

    2005-11-28

    Two coordination polymers formulated [Fe(pmd)2[Ag(CN)2]2] (pmd = pyrimidine) have been synthesized and characterized. Both polymers, considered to be architectural isomers, display different crystal structures and magnetic properties. Isomer 1 crystallizes in the monoclinic C2/c space group with a = 6.9750(8) angstroms, b = 16.1700(9) angstroms, c = 14.2020(8) angstroms, beta = 97.954(2) degrees, V = 1586.37(14) angstroms3, and Z = 4. The crystal structure of isomer 2 has been studied at 250 and 150 K. At both temperatures, 2 displays the orthorhombic Pccn space group with a = 15.7700(2) [14.8950(2)] angstroms, b = 8.2980(4) [8.1580(4)] angstroms, c = 13.4180(6) [13.3480(5)] angstroms, V = 1755.87(14) [1621.96(10)] angstroms3, and Z = 4 for 250 [150] K. The iron(II) ions define distorted octahedral [FeN6] chromophores in both isomers. The equatorial positions are occupied by four [Ag(CN)2]- bridging ligands, which connect the defining layers of two iron(II) ions. Isomer 1 has two crystallographically distinct [Ag(CN)2]- groups; one is essentially linear, while the other is severely distorted [C(5)-Ag(2)-C(5i)] = 138.8(5) degrees. This fact facilitates the parallel interpenetration of two layers, which in addition show short Ag(1)....Ag(2) interactions (distance Ag(1)....Ag(2) = 2.9972(10) angstroms). Isomer 2 shows only one type of Ag atom, which is slightly bent [C-Ag-C = 161.54(12) degrees], and as a consequence, the layers defined are not interpenetrated. In both cases, the axial positions are occupied by the pmd ligands which interact with the Ag atoms of adjacent layers defining a 3D coordination polymer. Compound 1 is high spin in the whole range of temperatures, while 2 undergoes a cooperative high-spin <--> low-spin effect centered at ca. 184 K with a hysteresis loop ca. 5 K wide. The experimental enthalpy and entropy variations were 11.5 +/- 0.4 kJ mol(-1) and 64 +/- 3 J K(-1) mol(-1). Consistency between the experimental thermodynamic data and the

  2. Turbulent fluctuations in the main core of TFTR plasmas with negative magnetic shear

    SciTech Connect

    Mazzucato, E.; Beer, M.; Bell, M.G.

    1997-04-01

    Turbulent fluctuations in plasmas with reversed magnetic shear have been investigated in TFTR. Under intense auxiliary heating, these plasmas are observed to bifurcate into two states with different transport properties. In the state with better confinement, it has been found that the level of fluctuations is very small throughout most of the region with negative shear. By contrast, the state with lower confinement is characterized by large bursts of fluctuations which suggest a competition between the driving and the suppression of turbulence. These results are consistent with the suppression of turbulence by the ExB velocity shear.

  3. Hierarchical Fe3O4@MoS2/Ag3PO4 magnetic nanocomposites: Enhanced and stable photocatalytic performance for water purification under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Guo, Na; Li, Haiyan; Xu, Xingjian; Yu, Hongwen

    2016-12-01

    Novel hierarchical Fe3O4@MoS2/Ag3PO4 magnetic nanophotocatalyst with remarkable photocatalytic capability were prepared by simply depositing the Ag3PO4 onto the surface of crumpled Fe3O4@MoS2 nanosphere. The nanocomposites were characterized by XRD, TEM, HRTEM, XPS, BET, and UV-vis DRS. The outcome of the photocatalytic experiments demonstrated that Fe3O4@MoS2/Ag3PO4 with 6 wt% content of Ag3PO4 (FM/A-6%) showed the highest photocatalytic activity upon the degradation Congo red (CR) and Rhodamine B (RhB) under both visible light and simulated sunlight irradiation. In addition, FM/A-6% possessed larger specific surface area (76.56 m2/g) and excellent optical property. The possible Z-scheme charge carriers transfer mechanism for the enhanced photocatalytic properties of the FM/A-6% was also discussed. The Z-scheme charge carriers transfer mechanism established between MoS2 and Ag3PO4 facilitate the charge separation efficiency. Moreover, FM/A-6% can be separated and collected easily by external magnetic field and maintain high activity after five times photoreaction cycles. Given the remarkable photocatalytic performance and high stability of FM/A-6% nanocomposite, it is looking forward to exhibit great potential for applications in water purification.

  4. Synthesis of magnetically separable Ag3PO4/TiO2/Fe3O4 heterostructure with enhanced photocatalytic performance under visible light for photoinactivation of bacteria.

    PubMed

    Xu, Jing-Wen; Gao, Zhi-Da; Han, Kun; Liu, Yongmin; Song, Yan-Yan

    2014-09-10

    Silver orthophosphate (Ag3PO4) is a low-band-gap photocatalyst that has received considerable research interest in recent years. In this work, the magnetic Ag3PO4/TiO2/Fe3O4 heterostructured nanocomposite was synthesized. The nanocomposite was found to exhibit markedly enhanced photocatalytic activity, cycling stability, and long-term durability in the photodegradation of acid orange 7 (AO7) under visible light. Moreover, the antibacterial film prepared from Ag3PO4/TiO2/Fe3O4 nanocomposite presented excellent bactericidal activity and recyclability toward Escherichia coli (E. coli) cells under visible-light irradiation. In addition to the intrinsic cytotoxicity of silver ions, the elevated bactericidal efficiency of Ag3PO4/TiO2/Fe3O4 can be largely attributed to its highly enhanced photocatalytic activity. The photogenerated hydroxyl radicals and superoxide ions on the formed Ag/Ag3PO4/TiO2 interfaces cause considerable morphological changes in the microorganism's cells and lead to the death of the bacteria.

  5. Facile synthesis and enhanced magnetic, photocatalytic properties of one-dimensional Ag@Fe3O4-TiO2

    NASA Astrophysics Data System (ADS)

    Jia, Xiaohua; Dai, Rongrong; Lian, Dandan; Han, Song; Wu, Xiangyang; Song, Haojie

    2017-01-01

    Fe3O4-TiO2 heterostructures were synthesized through co-precipitation method based on TiO2 nanobelts. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometry (VSM) were used to characterize the heterostructure nanocomposites. The results of XRD proved that the TiO2 nanobelt was anatase which was the most suitable crystal form for photocatalysis. SEM and TEM analysis indicated that Fe3O4 nanoparticles were adhere to TiO2 nanobelts which have one-dimensional structure with 100-200 nm in width. The VSM measurements showed that the photocatalyst can be easily recovered by an extemal magnetic field. X-ray photoelectron spectroscopy (XPS) of Ag@Fe3O4-TiO2 nanocomposites studies confirm that Ag is in Ag0 state. Finally, the photodegradation of rhodamine B (RhB) by the obtained magnetic photocatalyst was investigated via UV-vis absorption spectra. The photocatalytic activity of the composites was observed to be lower compared to bare TiO2 due to the higher degree of recombination reactions after combined with Fe3O4 nanoparticles. After coated the composite of 15% Fe3O4-TiO2 with Ag, the new nanocomposite of Ag@Fe3O4-TiO2 can be easily recovered after photocatalysis by an extemal magnetic field and showed enhanced photocatalytic activity. The mechanisms for the exhibited enhanced photocatalytic effect of Ag nanoparticle decorated Fe3O4-TiO2 nanocomposites with surface heterostructures are discussed.

  6. Low-temperature ferromagnetic properties in Co-doped Ag{sub 2}Se nanoparticles

    SciTech Connect

    Yang, Fengxia E-mail: xia9020@hust.edu.cn; Yu, Gen; Han, Chong; Liu, Tingting; Zhang, Duanming; Xia, Zhengcai E-mail: xia9020@hust.edu.cn

    2014-01-06

    β-Ag{sub 2}Se is a topologically nontrivial insulator. The magnetic properties of Co-doped Ag{sub 2}Se nanoparticles with Co concentrations up to 40% were investigated. The cusp of zero-field-cooling magnetization curves and the low-temperature hysteresis loops were observed. With increasing concentration of Co{sup 2+} ions mainly substituting Ag{sub I} sites in the Ag{sub 2}Se structure, the resistivity, Curie temperature T{sub c}, and magnetization increased. At 10 T, a sharp drop of resistance near T{sub c} was detected due to Co dopants. The ferromagnetic behavior in Co-doped Ag{sub 2}Se might result from the intra-layer ferromagnetic coupling and surface spin. This magnetic semiconductor is a promising candidate in electronics and spintronics.

  7. Interaction transfer of silicon atoms forming Co silicide for Co/√(3)×√(3)R30°-Ag/Si(111) and related magnetic properties

    SciTech Connect

    Chang, Cheng-Hsun-Tony; Fu, Tsu-Yi; Tsay, Jyh-Shen

    2015-05-07

    Combined scanning tunneling microscopy, Auger electron spectroscopy, and surface magneto-optic Kerr effect studies were employed to study the microscopic structures and magnetic properties for ultrathin Co/√(3)×√(3)R30°-Ag/Si(111). As the annealing temperature increases, the upward diffusion of Si atoms and formation of Co silicides occurs at temperature above 400 K. Below 600 K, the √(3)×√(3)R30°-Ag/Si(111) surface structure persists. We propose an interaction transferring mechanism of Si atoms across the √(3)×√(3)R30°-Ag layer. The upward transferred Si atoms react with Co atoms to form Co silicide. The step height across the edge of the island, a separation of 0.75 nm from the analysis of the 2 × 2 structure, and the calculations of the normalized Auger signal serve as strong evidences for the formation of CoSi{sub 2} at the interface. The interaction transferring mechanism for Si atoms enhances the possibility of interactions between Co and Si atoms. The smoothness of the surface is advantage for that the easy axis of magnetization for Co/√(3)×√(3)R30°-Ag/Si(111) is in the surface plane. This provides a possible way of growing flat magnetic layers on silicon substrate with controllable silicide formation and shows potential applications in spintronics devices.

  8. Novel Fe3O4@SiO2@Ag@Ni trepang-like nanocomposites: High-efficiency and magnetic recyclable catalysts for organic dye degradation

    NASA Astrophysics Data System (ADS)

    Li, Chao; Sun, Jun-Jie; Chen, Duo; Han, Guang-Bing; Yu, Shu-Yun; Kang, Shi-Shou; Mei, Liang-Mo

    2016-08-01

    A facile step-by-step approach is developed for synthesizing the high-efficiency and magnetic recyclable Fe3O4@SiO2@Ag@Ni trepang-like nanocomposites. This method involves coating Fe2O3 nanorods with a uniform silica layer, reduction in 10% H2/Ar atmosphere to transform the Fe2O3 into magnetic Fe3O4, and finally depositing Ag@Ni core-shell nanoparticles on the L-lysine modified surface of Fe3O4@SiO2 nanorods. The fabricated nanocomposites are further characterized by x-ray diffraction, transmission electron microscopy, scanning electron microscope, Fourier transform infrared spectroscopy, and inductively coupled plasma mass spectroscopy. The Fe3O4@SiO2@Ag@Ni trepang-like nanocomposites exhibit remarkably higher catalytic efficiency than monometallic Fe3O4@SiO2@Ag nanocomposites toward the degradation of Rhodamine B (RhB) at room temperature, and maintain superior catalytic activity even after six cycles. In addition, these samples could be easily separated from the catalytic system by an external magnet and reused, which shows great potential applications in treating waste water. Project supported by the National Basic Research Program of China (Grant No. 2015CB921502), the National Natural Science Foundation of China (Grant Nos. 11474184 and 11174183), the 111 Project (Grant No. B13029), and the Fundamental Research Funds of Shandong University, China.

  9. Main Characteristics of the VLF Magnetic Field Waves Recorded by the Search Coil Magnetometer Experiment Onboard the CUSP Sounding Rocket

    NASA Astrophysics Data System (ADS)

    Pinçon, J.; Krasnoselskikh, V.; de Feraudy, H.; Rezeau, L.; Robert, P.; Pfaff, R. F.

    2003-12-01

    The CUSP rocket is a NASA Black Brant X sounding rocket dedicated to the exploration of the electrodynamic coupling, pulsations, and acceleration processes in the dayside cusp and the boundary layer interface. The launch occured on December 14, 2002, from Ny Åleysund, Spitzbergen (79° N) during Bz negative conditions. We present the magnetic field waves measurement collected in the frequency range [10 Hz - 10 kHz] by the three axis Search Coil Magnetometer (SCM) experiment onboard CUSP. The observations reveal the presence of intense field fluctuations corresponding to ELF hiss which is only seen on closed field lines and hence can be used to define the magnetic boundary of the cusp. Several data analysis techniques were applied to the 3 components of the magnetic field fluctuations associated with the ELF hiss to obtain information regarding the wave polarization and the wave vector directions. The magnetic field wave data are compared with simultaneous observations of electric field wave data to further enhance our understanding of these wave phenomena. The main results coming from this detailed study are presented and discussed.

  10. Structural and magnetic phase transitions in CeCu6-xTx (T = Ag,Pd)

    SciTech Connect

    Poudel, Lekhanath N.; De la cruz, Clarina; Payzant, E. Andrew; Koehler, Michael R.; May, Andrew F.; Garlea, Vasile O.; Taylor, Alice E.; Parker, David S.; Cao, Huibo B.; McGuire, Michael A.; Tian, Wei; Matsuda, Masaaki; Jeen, Hyoung Jeen; Lee, Ho Nyung; Hong, Tao; Calder, Stuart A.; Lumsden, Mark D.; Zhou, Haidong; Keppens, Veerle; Mandrus, D.; Christianson, Andrew D.

    2015-12-15

    The structural and the magnetic properties of CeCu6-xAgx (0 ≤ x ≤ 0.85) and CeCu6-xPdx (0 ≤ x ≤ 0.4) have been studied using neutron diffraction, resonant ultrasound spectroscopy (RUS), x-ray diffraction measurements, and first principles calculations. The structural and magnetic phase diagrams of CeCu6-xAgx and CeCu6-xPdx as a function of Ag/Pd composition are reported. The end member, CeCu6, undergoes a structural phase transition from an orthorhombic (Pnma) to a monoclinic (P21/c) phase at 240 K. In CeCu6-xAgx, the structural phase transition temperature (Ts) decreases linearly with Ag concentration and extrapolates to zero at xS ≈ 0.1. The structural transition in CeCu6-xPdx remains unperturbed with Pd substitution within the range of our study. The lattice constant b slightly decreases with Ag/Pd doping, whereas a and c increase with an overall increase in the unit cell volume. Both systems, CeCu6-xAgx and CeCu6-xPdx, exhibit a magnetic quantum critical point (QCP), at x ≈ 0.2 and x ≈ 0.05, respectively. Near the QCP, long range antiferromagnetic ordering takes place at an incommensurate wave vector (δ1 0 δ2), where δ1 ~ 0.62, δ2 ~ 0.25, x = 0.125 for CeCu6-xPdx and δ1 ~ 0.64, δ2 ~ 0.3, x = 0.3 for CeCu6-xAgx. As a result, the magnetic structure consists of an amplitude modulation of the Ce moments which are aligned along the c axis of the orthorhombic unit cell.

  11. Performance of pancake coils of parallel co-wound Ag/BSCCO tape conductors in static and ramped magnetic fields

    SciTech Connect

    Schwenterly, S.W.; Lue, J.W.; Lubell, M.S.; Walker, M.S.; Hazelton, D.W.; Haldar, P.; Rice, J.A.; Hoehn, J.G. Jr.; Motowidlo, L.R.

    1994-12-31

    Critical Currents are reported for several Ag/BSCCO single-pancake coils in static magnetic fields ranging from 0 to 5 T and temperatures from 4.2 K to 105 K. The sample coils were co-wound of one to six tape conductors in parallel. Since the closed loops formed in such an arrangement could lead to eddy current heating or instability in changing fields, one of the coils was also tested in helium gas, in fields ramped at rates of up to 1.5 T/s. For these quasi-adiabatic tests, at each temperature the transport current was set just below the critical value for a preset static field of 3.3 or 4.9 T. The field was then rapidly ramped down to zero, held for 20 sec, and then ramped back up to the original value. The maximum observed temperature transient of about 1.7 K occurred at 9 K, for a field change of 4.75 T. The temperature transients became negligible when the sample was immersed in liquid helium. Above 30 K, the transients were below 1 K. These results give confidence that parallel co-wound HTSC coils are stable in a rapidly-ramped magnetic field, without undue eddy current heating.

  12. Effect of parallel and antiparallel configuration on magnetic damping in Co/Ag/Co/Gd

    NASA Astrophysics Data System (ADS)

    Demirtas, S.; Salamon, M. B.; Koymen, A. R.

    2011-06-01

    When two ferromagnetic layers have a common resonance frequency, the usual spin-pumping broadening may be reduced by dynamic exchange coupling. Utilizing the antiferromagnetic coupling between Co and Gd, we explore the change in ferromagnetic resonance accompanying a spontaneous transition from parallel to antiparallel magnetic alignment of two Co films below the compensation temperature Tcomp. Above Tcomp, the data are consistent with conventional models. However, a rapid doubling of magnetic damping accompanies the realignment, which is reminiscent of resistivity changes in giant magnetoresistance.

  13. Spin and orbital magnetism of coinage metal trimers (Cu{sub 3}, Ag{sub 3}, Au{sub 3}): A relativistic density functional theory study

    SciTech Connect

    Afshar, Mahdi; Sargolzaei, Mohsen

    2013-11-15

    We have demonstrated electronic structure and magnetic properties of Cu{sub 3}, Ag{sub 3} and Au{sub 3} trimers using a full potential local orbital method in the framework of relativistic density functional theory. We have also shown that the non-relativistic generalized gradient approximation for the exchange-correlation energy functional gives reliable magnetic properties in coinage metal trimers compared to experiment. In addition we have indicated that the spin-orbit coupling changes the structure and magnetic properties of gold trimer while the structure and magnetic properties of copper and silver trimers are marginally affected. A significant orbital moment of 0.21μ{sub B} was found for most stable geometry of the gold trimer whereas orbital magnetism is almost quenched in the copper and silver trimers.

  14. Synthesis of magnetically recyclable MnFe2O4@SiO2@Ag nanocatalyst: Its high catalytic performances for azo dyes and nitro compounds reduction

    NASA Astrophysics Data System (ADS)

    Kurtan, U.; Amir, Md.; Yıldız, A.; Baykal, A.

    2016-07-01

    In this study, magnetically recycable MnFe2O4@SiO2@Ag nanocatalyst (MnFe2O4@SiO2@Ag MRCs) has been synthesized through co-precipition and chemical reduction method. XRD analysis confirmed the synthesis of single phase nanoproduct with crystallite size of 10 nm. VSM measurements showed the superparamagnetic property of the product. Catalytic studies showed that MnFe2O4@SiO2@Ag MRC could catalyze the reduction of the various azo compounds like methyl orange (MO), methylene blue (MB), eosin Y (EY), and rhodamine B (RhB) and also aromatic nitro compounds such as 4-nitrophenol (4-NP), 4-nitroaniline (4-NA) and 2-nitroaniline (2-NA). Moreover, the magnetic nanocatalyst showed an excellent reusability properties that remained unchanged after several cycles. Therefore, MnFe2O4@SiO2@Ag is the potential candidate for the application of organic pollutants for wastewater treatment.

  15. Variability of stellar granulation and convective blueshift with spectral type and magnetic activity. I. K and G main sequence stars

    NASA Astrophysics Data System (ADS)

    Meunier, N.; Lagrange, A.-M.; Mbemba Kabuiku, L.; Alex, M.; Mignon, L.; Borgniet, S.

    2017-01-01

    Context. In solar-type stars, the attenuation of convective blueshift by stellar magnetic activity dominates the RV (radial velocity) variations over the low amplitude signal induced by low mass planets. Models of stars that differ from the Sun will require a good knowledge of the attenuation of the convective blueshift to estimate its impact on the variations. Aims: It is therefore crucial to precisely determine not only the amplitude of the convective blueshift for different types of stars, but also the dependence of this convective blueshift on magnetic activity, as these are key factors in our model producing the RV. Methods: We studied a sample of main sequence stars with spectral types from G0 to K2 and focused on their temporally averaged properties: the activity level and a criterion allowing to characterise the amplitude of the convective blueshift. This criterion is derived from the dependence of the convective blueshift with the intensity at the bottom of a large set of selected spectral lines. Results: We find the differential velocity shifts of spectral lines due to convection to depend on the spectral type, the wavelength (this dependence is correlated with the Teff and activity level), and on the activity level. This allows us to quantify the dependence of granulation properties on magnetic activity for stars other than the Sun. We are indeed able to derive a significant dependence of the convective blueshift on activity level for all types of stars. The attenuation factor of the convective blueshift appears to be constant over the considered range of spectral types. We derive a convective blueshift which decreases towards lower temperatures, with a trend in close agreement with models for Teff lower than 5800 K, but with a significantly larger global amplitude. Differences also remain to be examined in detail for larger Teff. We finally compare the observed RV variation amplitudes with those that could be derived from our convective blueshift using

  16. 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.

  17. 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.

  18. Cyto/hemocompatible magnetic hybrid nanoparticles (Ag2S-Fe3O4) with luminescence in the near-infrared region as promising theranostic materials.

    PubMed

    Hocaoglu, Ibrahim; Asik, Didar; Ulusoy, Gulen; Grandfils, Christian; Ojea-Jimenez, Isaac; Rossi, François; Kiraz, Alper; Doğan, Nurcan; Acar, Havva Yagci

    2015-09-01

    Small hybrid nanoparticles composed of highly biocompatible Ag2S quantum dots (QD) emitting in the near-infrared region and superparamagnetic iron oxide (SPION) are produced in a simple extraction method utilizing ligand exchange mechanism. Hybrid nanoparticles luminesce at the same wavelength as the parent QD, therefore an array of hybrid nanoparticles with emission between 840 and 912nm were easily produced. Such hybrid structures have (1) strong luminescence in the medical imaging window eliminating the autofluoresence of cells as effective optical probes, (2) strong magnetic response for magnetic targeting and (3) good cyto/hemocompatibility. An interesting size dependent cytotoxicity behavior was observed in HeLa and NIH/3T3 cell lines: smallest particles are internalized significantly more by both of the cell lines, yet showed almost no significant cytotoxicity in HeLa between 10 and 25μg/mL Ag concentration but were most toxic in NIH/3T3 cells. Cell internalization and hence the cytotoxicity enhanced when cells were incubated with the hybrid nanoparticles under magnetic field, especially with the hybrid nanoparticles containing larger amounts of SPION in the hybrid composition. These results prove them as effective optical imaging agents and magnetic delivery vehicles. Combined with the known advantages of SPIONs as a contrast agent in MRI, these particles are a step forward for new theranostics for multimode imaging and magnetic targeting.

  19. Determination of the Fe magnetic anisotropies and the CoO frozen spins in epitaxial CoO/Fe/Ag(001)

    SciTech Connect

    Meng, J. Li, Y.; Park, J. S.; Jenkins, C. A.; Arenholz, E.; Scholl, A.; Tan, A.; Son, H.; Zhao, H. W.; Hwang, Chanyong; Qiu, Z. Q.

    2011-04-28

    CoO/Fe/Ag(001) films were grown epitaxially and studied by X-ray Magnetic Circular Dichroism (XMCD) and X-ray Magnetic Linear Dichroism (XMLD). After field cooling along the Fe[100] axis to 80 K, exchange bias, uniaxial anisotropy, and 4-fold anisotropy of the films were determined by hysteresis loop and XMCD measurements by rotating the Fe magnetization within the film plane. The CoO frozen spins were determined by XMLD measurement as a function of CoO thickness.We find that among the exchange bias, uniaxial anisotropy, and 4-fold anisotropy, only the uniaxial magnetic anisotropy follows thickness dependence of the CoO frozen spins.

  20. Correlation of electrical, magnetic, and thermal properties of the La0.85Ag0.15MnO3 manganite near the phase transition temperature

    NASA Astrophysics Data System (ADS)

    Gamzatov, A. G.; Batdalov, A. B.; Kaul', A. R.; Mel'nikov, O. V.

    2011-01-01

    The correlation between electrical, magnetic, and lattice properties of manganites has been studied by analyzing the temperature dependence of the electrical resistivity of the La0.85Ag0.15MnO3 manganite. The results have been discussed within the model of a phase-separated manganite in terms of the percolation theory. It has been shown that, from analyzing the temperature and magnetic field dependences of the electrical resistivity, it is possible to predict the behavior of the magnetization and specific heat, as well as the change of magnetic entropy near the phase transition temperature, and that the obtained agreement with experimental data for this analysis is quite reasonable.

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

    PubMed

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

    2013-07-10

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

  2. Exploring the thermoelectric and magnetic properties of uranium selenides: Tl2Ag2USe4 and Tl3Cu4USe6

    NASA Astrophysics Data System (ADS)

    Azam, Sikander; Khan, Saleem Ayaz; Din, Haleem Ud; Khenata, Rabah; Goumri-Said, Souraya

    2016-09-01

    The electronic, magnetic and thermoelectric properties of Tl2Ag2USe4 and Tl3Cu4USe6 compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin-orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl2Ag2USe4 and Tl3Cu4USe6 respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl3Cu4USe6 is more suitable for thermoelectric device applications than Tl2Ag2USe4.

  3. Magnetically separable Fe3O4@SiO2@TiO2-Ag microspheres with well-designed nanostructure and enhanced photocatalytic activity.

    PubMed

    Chi, Yue; Yuan, Qing; Li, Yanjuan; Zhao, Liang; Li, Nan; Li, Xiaotian; Yan, Wenfu

    2013-11-15

    Major efforts in modern material chemistry are devoted to the design and fabrication of nanostructured systems with tunable physical-chemical properties for advanced catalytic applications. Here, a novel Fe3O4@SiO2@TiO2-Ag nanocomposite has been synthesized and characterized by a series of techniques including SEM, TEM, XRD, XPS as well as magnetization measurement and subsequently tested for the photocatalytic activities. The well-designed nanocomposite exhibits significantly superior activity to that of the commercial Degussa P25 thanks to the suppression of electron-hole pairs from recombination by Ag nanoparticles, and can be easily recycled by applying an external magnetic field while maintaining the catalytic activity without significant decrease even after running 10 times. The unique nanostructure makes Fe3O4@SiO2@TiO2-Ag a highly efficient, recoverable, stable, and cost-effective photocatalytic system offering broad opportunities in the field of catalyst synthesis and application.

  4. Synthesis of Bifunctional Fe3O4@SiO2-Ag Magnetic-Plasmonic Nanoparticles by an Ultrasound Assisted Chemical Method

    NASA Astrophysics Data System (ADS)

    Chu, Dung Tien; Sai, Doanh Cong; Luu, Quynh Manh; Tran, Hong Thi; Quach, Truong Duy; Kim, Dong Hyun; Nguyen, Nam Hoang

    2017-03-01

    Bifunctional magnetic-plasmonic nanoparticles (NPs)—Fe3O4@SiO2-Ag were successfully synthesized by an ultrasound assisted chemical method. Silver ions were absorbed and then reduced by sodium borohydride on the surface of 3-aminopropyltriethoxysilane (APTES) functionalized silica-coated magnetic NPs, then they were reduced under the influence of a 200 W ultrasonic wave for 60 min. When the amount of precursor silver ions increased, the relative intensity of diffraction peaks of silver crystals in all samples increased with the atomic ratio of silver/iron increasing from 0.208 to 0.455 and saturation magnetization (M s) decreasing from 44.68 emu/g to 34.74 emu/g. The NPs have superparamagnetic properties and strong surface plasmon absorption at 420 nm, which make these particles promising for biomedical applications.

  5. Enhanced photophysical properties of plasmonic magnetic metal-alloyed semiconductor heterostructure nanocrystals: a case study for the Ag@Ni/Zn1-xMgxO system.

    PubMed

    Paul, Sumana; Ghosh, Sirshendu; Saha, Manas; De, S K

    2016-05-14

    Understanding the effect of homovalent cation alloying in wide band gap ZnO and the formation of metal-semiconductor heterostructures is very important for maximisation of the photophysical properties of ZnO. Nearly monodisperse ZnO nanopyramid and Mg alloyed ZnO nanostructures have been successfully synthesized by one pot decomposition of metal stearate by using oleylamine both as activating and capping agent. The solid solubility of Mg(ii) ions in ZnO is limited to ∼30% without phase segregation. An interesting morphology change is found on increasing Mg alloying: from nanopyramids to self-assembled nanoflowers. The morphology change is explained by the oriented attachment process. The introduction of Mg into the ZnO matrix increases the band gap of the materials and also generates new zinc interstitial (Zni) and oxygen vacancy related defects. Plasmonic magnetic Ag@Ni core-shell (Ag as core and Ni as shell) nanocrystals are used as a seed material to synthesize Ag@Ni/Zn1-xMgxO complex heterostructures. Epitaxial growth is established between Ag(111) and ZnO(110) planes in the heterostructure. An epitaxial metal-semiconductor interface is very crucial for complete electron-hole (e-h) separation and enhancement of the exciton lifetime. The alloyed semiconductor-metal heterostructure is observed to be highly photocatalytically active for dye degradation as well as photodetection. Incorporation of magnetic Ni(0) makes the photocatalyst superparamagnetic at room temperature which is found to be helpful for catalyst regeneration.

  6. Local and Cooperative Jahn-Teller Effect and Resultant Magnetic Properties of M2AgF4 (M = Na-Cs) Phases.

    PubMed

    Kurzydłowski, Dominik; Jaroń, Tomasz; Ozarowski, Andrew; Hill, Stephen; Jagličić, Zvonko; Filinchuk, Yaroslav; Mazej, Zoran; Grochala, Wojciech

    2016-11-07

    The crystal structure, magnetic properties, heat capacity, and Raman spectra of double-perovskite M2AgF4 (M = K, K3/4Rb1/4, K1/2Rb1/2, K1/4Rb3/4, and Rb) phases have been examined, adding to the body of previous results for the M = Na, Cs derivatives. The results suggest that double-perovskite K2AgF4 adopts a disordered orthorhombic Bmab structure with an antiferrodistortive arrangement of the elongated and tilted [AgF6] octahedra rather than the structure with the ferrodistortive arrangement of compressed octahedra, as suggested previously (Mazej, Z.; Goreshnik, E.; Jagličić, Z.; Gaweł, B.; Łasocha, W.; Grzybowska, D.; Jaroń, T.; Kurzydłowski, D.; Malinowski, P. J.; Koźmiński, W.; Szydłowska, J.; Leszczyński, P. J.; Grochala, W. KAgF3, K2AgF4 and K3Ag2F7: important steps towards a layered antiferromagnetic fluoroargentate(II). CrystEngComm 2009, 11, 1702-1710). A re-examination of the previously collected single-crystal X-ray diffraction data confirms the current structure assignment, and it is also in agreement with recent theoretical calculations. High-field electron paramagnetic resonance spectra reaffirm the presence of elongated [AgF6] octahedra in the crystal structure of all M2AgF4 phases studied. The local structure of the M = K derivative is most complex, with regions of the sample that are quite orthorhombically distorted, whereas other regions more closely resemble the tetragonal phase. The mixed-cation K/Rb phases are also inhomogeneous, containing regions of the pure K compound and regions of another high-symmetry phase (likely tetragonal) of a mixed (Rb-richer) compound with unknown composition. The temperature-resolved phase diagram of all K/Rb phases has been established and positioned within the entire M = Na, K, Rb, Cs series.

  7. Universal main magnetic focus ion source: A new tool for laboratory research of astrophysics and Tokamak microplasma

    NASA Astrophysics Data System (ADS)

    Ovsyannikov, V. P.; Nefiodov, A. V.; Levin, A. A.

    2017-01-01

    A novel room-temperature ion source for the production of atomic ions in electron beam within wide ranges of electron energy and current density is developed. The device can operate both as conventional Electron Beam Ion Source/Trap (EBIS/T) and novel Main Magnetic Focus Ion Source. The ion source is suitable for generation of the low-, medium- and high-density microplasma in steady state, which can be employed for investigation of a wide range of physical problems in ordinary university laboratory, in particular, for microplasma simulations relevant to astrophysics and ITER reactor. For the electron beam characterized by the incident energy Ee = 10 keV, the current density je ∼ 20 kA/cm2 and the number density ne ∼ 2 × 1013 cm‑3 were achieved experimentally. For Ee ∼ 60 keV, the value of electron number density ne ∼ 1014 cm‑3 is feasible. The efficiency of the novel ion source for laboratory astrophysics significantly exceeds that of other existing warm and superconducting EBITs.

  8. Hydrothermal synthesis of Ag@TiO2-Fe3O4 nanocomposites using sonochemically activated precursors: magnetic, photocatalytic and antibacterial properties

    NASA Astrophysics Data System (ADS)

    Bokare, Anuja; Singh, Hema; Pai, Mrinal; Nair, Roopa; Sabharwal, Sushma; Athawale, Anjali A.

    2014-12-01

    Fe3O4-TiO2 nanocomposites have been synthesized by hydrothermal method using sonochemically activated precursors. X-ray diffraction analysis of the samples reveals the formation of pure phase composites. The optical properties of the composites are superior to TiO2 as noted from the red shift in the diffused reflectance spectra of the composites. The presence of nanocubes of Fe3O4, nanospheres of TiO2 and heterojunctions of the two in the composite samples have been observed in transmission electron micrographs. The magnetic properties of the samples were determined with the help of vibrating sample magnetometry (VSM) and magnetic force microscopy (MFM). The photocatalytic activity of the samples was investigated in terms of degradation of methyl orange (MO) dye. The composites could be easily separated from the reaction mixture after photocatalysis due to their magnetic behaviour. However, the photocatalytic activity of the composites was observed to be lower compared to bare TiO2. The composite (15% Fe3O4-TiO2) when modified by coating it with Ag showed enhanced photocatalytic activity. Further, the antibacterial activities of the samples were also examined using E. coli as a model organism. Positive results were obtained only for the Ag coated composite with lower MIC (minimum inhibition concentration) values.

  9. Synthesis of core-shell nanostructured magnetic photocatalyst Fe3O4@SiO2@Ag3PO4 with excellent visible-light-responding photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Yao, Yang Rong; Huang, Wan Zhen; Zhou, Huan; Cui, Xia; Zheng, Yi Fan; Song, Xu Chun

    2014-11-01

    A core-shell nanostructured magnetic photocatalyst Fe3O4@SiO2@Ag3PO4 with a grain size ranging from 200 to 400 nm was prepared via a facile and effective method. The as-prepared products were characterized using X-ray diffraction, high-angle annular dark field-scanning transmission electron microscopy, energy-dispersive spectroscopy, and UV-Vis diffuse reflectance spectra. The photocatalytic activity was evaluated by the degradation of 10-5 M RhB solution under visible light irradiation with a cut-off filter ( λ ≥ 420 nm). The results showed that nearly 100 % color removal efficiency was achieved in 45 min with the presence of Fe3O4@SiO2@Ag3PO4 photocatalyst. Furthermore, it can be easily recollected from the solution by magnetic separation and efficiently recycled without major loss of activity due to its superior magnetic responsibility and extremely high reusability, exhibiting highly potential applications in water purification avoiding the secondary pollution.

  10. Magnetic AC loss of a mono-Sr0.6K0.4Fe2As2 tape/Ag in perpendicular field

    NASA Astrophysics Data System (ADS)

    Liu, Qi; Zhang, Guomin; Yu, Hui; Huang, Miaomiao; Yuan, Weijia

    2016-12-01

    The magnetic AC losses of monofilament Sr0.6K0.4Fe2As2/Ag tapes are measured in the temperature range between 20 K and 30 K both in perpendicular and parallel field. The loss, measured by the standard magnetization technique, is determined from the area of the hysteresis loop using a vibrating sample magnetometer (VSM) in a cyclic field of amplitude up to 7 T. The results in perpendicular field are compared to that of the parallel-field loss and theoretical calculation of magnetization loss at various temperatures. There is a reasonable agreement between the theoretical model and the experimental results even in high field. The magnetic critical current density (Jc) of the tape, obtained by the magnetic hysteresis measurements M(H), are investigated in two field directions and in the temperature range from 5 K to 30 K. The comparison between the magnetic Jc in both field directions and the transport Jc of the tape are also done at various temperatures and fields. The anisotropy of Jc (Γ = Jcab /Jcc) is very small.

  11. Heteronuclear, mixed-metal Ag(I)-Mn(II) coordination polymers with bridging N-pyridinylisonicotinohydrazide ligands: synthesis, crystal structures, magnetic and photoluminescence properties.

    PubMed

    Bikas, Rahman; Hosseini-Monfared, Hassan; Vasylyeva, Vera; Sanchiz, Joaquín; Alonso, Javier; Barandiaran, Jose Manuel; Janiak, Christoph

    2014-08-21

    Mixed-metal dicyanoargentate-bridged coordination polymers of Ag(i)-Mn(ii) have been prepared and their structure and magnetic properties were determined. Reaction of manganese(ii) chloride and potassium dicyanoargentate(i) with (X)(pyridin-2-ylmethylene)isonicotinohydrazide ligands (HL(1) X = Ph, HL(2) X = Me, HL(3) X = H) produced the coordination polymer 2D-[Mn(μ-L(1))(Cl)(μ-NCAgCN)Mn0.5(CH3OH)]n (), 1D-{[Mn(L(2))(Cl)(μ-NCAgCN)Mn0.5(CH3OH)]CH3OH}n () and [Mn(L(3))(Cl)(μ-NCAgCN)Mn0.5(CH3OH)]n () in good yields. Trinuclear {Mn(μ-L(1))Mn(μ-L(1))Mn} and [Ag(CN)2](-) building units form a two-dimensional slab in and 1D strands in . Variable temperature magnetic susceptibility measurements showed that despite the long distance among the high spin Mn(ii) ions [10.4676(12) Å and 10.522(1) Å, for and , respectively], weak antiferromagnetic coupling takes place through the long NC-Ag-CN bridge. The best fit parameters to the model led to the magnetic coupling constant of J = -0.1 and J = -0.47 cm(-1) for and , respectively. The photoluminescence behaviour of compounds and was studied. The spectrum of compound shows a broad emission centered at about 450 nm and two excitation maxima at 270 and 310 nm.

  12. Preparation of surface plasmon resonance biosensor based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles.

    PubMed

    Wang, Liying; Sun, Ying; Wang, Jing; Wang, Jian; Yu, Aimin; Zhang, Hanqi; Song, Daqian

    2011-06-01

    In this paper, surface plasmon resonance biosensors based on magnetic core/shell Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were developed for immunoassay. With Fe(3)O(4) and Fe(3)O(4)/Ag nanoparticles being used as seeding materials, Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were formed by hydrolysis of tetraethyl orthosilicate. The aldehyde group functionalized magnetic nanoparticles provide organic functionality for bioconjugation. The products were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), FTIR and UV-vis absorption spectrometry. The magnetic nanoparticles possess the unique superparamagnetism property, exceptional optical properties and good compatibilities, and could be used as immobilization matrix for goat anti-rabbit IgG. The magnetic nanoparticles can be easily immobilized on the surface of SPR biosensor chip by a magnetic pillar. The effects of Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles on the sensitivity of SPR biosensors were also investigated. As a result, the SPR biosensors based on Fe(3)O(4)/SiO(2) nanoparticles and Fe(3)O(4)/Ag/SiO(2) nanoparticles exhibit a response for rabbit IgG in the concentration range of 1.25-20.00 μg ml(-1) and 0.30-20.00 μg ml(-1), respectively.

  13. Main Cause of the Poloidal Plasma Motion Inside a Magnetic Cloud Inferred from Multiple-Spacecraft Observations

    NASA Astrophysics Data System (ADS)

    Zhao, Ake; Wang, Yuming; Chi, Yutian; Liu, Jiajia; Shen, Chenglong; Liu, Rui

    2017-04-01

    Although the dynamical evolution of magnetic clouds (MCs) has been one of the foci of interplanetary physics for decades, only few studies focus on the internal properties of large-scale MCs. Recent work by Wang et al. ( J. Geophys. Res. 120, 1543, 2015) suggested the existence of the poloidal plasma motion in MCs. However, the main cause of this motion is not clear. In order to find it, we identify and reconstruct the MC observed by the Solar Terrestrial Relations Observatory (STEREO)-A, Wind, and STEREO-B spacecraft during 19 - 20 November 2007 with the aid of the velocity-modified cylindrical force-free flux-rope model. We analyze the plasma velocity in the plane perpendicular to the MC axis. It is found that there was evident poloidal motion at Wind and STEREO-B, but this was not clear at STEREO-A, which suggests a local cause rather than a global cause for the poloidal plasma motion inside the MC. The rotational directions of the solar wind and MC plasma at the two sides of the MC boundary are found to be consistent, and the values of the rotational speeds of the solar wind and MC plasma at the three spacecraft show a rough correlation. All of these results illustrate that the interaction with ambient solar wind through viscosity might be one of the local causes of the poloidal motion. Additionally, we propose another possible local cause: the existence of a pressure gradient in the MC. The significant difference in the total pressure at the three spacecraft suggests that this speculation is perhaps correct.

  14. Modelling of the AGS using Zgoubi - Status

    SciTech Connect

    Meot F.; Ahrens, L.; Dutheil, Y.; Glenn, J.; Huang, H.; Roser, T.; Schoefer, V.; Tsoupas, N.

    2012-05-20

    This paper summarizes the progress achieved so far, and discusses various outcomes, regarding the development of a model of the Alternating Gradient Synchrotron at the RHIC collider. The model, based on stepwise ray-tracing methods, includes beam and polarization dynamics. This is an on-going work, and a follow-on of code developments and particle and spin dynamics simulations that have been subject to earlier publications at IPAC and PAC [1, 2, 3]. A companion paper [4] gives additional informations, regarding the use of the measured magnetic field maps of the AGS main magnets.

  15. Temperature-dependent roles of inter- and intragrain current systems on the critical current and magnetization of BSCCO-2223/Ag tapes

    NASA Astrophysics Data System (ADS)

    Paasi, Jaakko; Kottman, Peter; Polák, Milan

    1995-02-01

    In this study we examine the role of inter- and intragrain current systems on the temperature-dependent critical current and magnetization of BSCCO-2223/Ag tapes. Experiments were done by measuring the sample magnetization field with movable miniature Hall sensors. We found that both systems have their own irreversible characteristics. The overall level of the intergrain (transport) critical current density, Jc, was limited at both lower (<30 K) and higher temperatures (30-95 K) by intergranular flux pinning, which seemed to be related to the maximum Josephson current of the weak links. Furthermore, we found that the irreversible intragranular magnetization has an influence on the magnetic field dependence of the intergrain Jc: when the intragrain pinning is strong (as at lower temperatures), the reduction of Jc in magnetic fields is moderate, and, when it is weaker (at higher temperatures), the decrease of Jc in fields is strong. This is a consequence of the field dependence of the maximum Josephson current density of the weak links, when the adjacent superconducting grains are in the mixed state.

  16. Coinage metals binding as main group elements: structure and bonding of the carbene complexes [TM(cAAC)2] and [TM(cAAC)2](+) (TM = Cu, Ag, Au).

    PubMed

    Jerabek, Paul; Roesky, Herbert W; Bertrand, Guy; Frenking, Gernot

    2014-12-10

    Quantum chemical calculations using density functional theory have been carried out for the cyclic (alkyl)(amino)carbene (cAAC) complexes of the group 11 atoms [TM(cAAC)2] (TM = Cu, Ag, Au) and their cations [TM(cAAC)2](+). The nature of the metal-ligand bonding was investigated with the charge and energy decomposition analysis EDA-NOCV. The calculations show that the TM-C bonds in the charged adducts [TM(cAAC)2](+) are significantly longer than in the neutral complexes [TM(cAAC)2], but the cations have much higher bond dissociation energies than the neutral molecules. The intrinsic interaction energies ΔEint in [TM(cAAC)2](+) take place between TM(+) in the (1)S electronic ground state and (cAAC)2. In contrast, the metal-ligand interactions in [TM(cAAC)2] involve the TM atoms in the excited (1)P state yielding strong TM p(π) → (cAAC)2 π backdonation, which is absent in the cations. The calculations suggest that the cAAC ligands in [TM(cAAC)2] are stronger π acceptors than σ donors. The trends of the intrinsic interaction energies and the bond dissociation energies of the metal-ligand bonds in [TM(cAAC)2] and [TM(cAAC)2](+) give the order Au > Cu > Ag. Calculations at the nonrelativistic level give weaker TM-C bonds, particularly for the gold complexes. The trend for the bond strength in the neutral and charged adducts without relativistic effects becomes Cu > Ag > Au. The EDA-NOCV calculations suggest that the weaker bonds at the nonrelativistic level are mainly due to stronger Pauli repulsion and weaker orbital interactions. The NBO picture of the C-TM-C bonding situation does not correctly represent the nature of the metal-ligand interactions in [TM(cAAC)2].

  17. 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.

  18. Effect of NiO spin orientation on the magnetic anisotropy of the Fe film in epitaxially grown Fe/NiO/Ag(001) and Fe/NiO/MgO(001)

    SciTech Connect

    Kim, W.; Jin, E.; Wu, J.; Park, J.; Arenholz, E.; Scholl, A.; Hwang, C.; Qiu, Z.

    2010-02-10

    Single crystalline Fe/NiO bilayers were epitaxially grown on Ag(001) and on MgO(001), and investigated by Low Energy Electron Diffraction (LEED), Magneto-Optic Kerr Effect (MOKE), and X-ray Magnetic Linear Dichroism (XMLD). We find that while the Fe film has an in-plane magnetization in both Fe/NiO/Ag(001) and Fe/NiO/MgO(001) systems, the NiO spin orientation changes from in-plane direction in Fe/NiO/Ag(001) to out-of-plane direction in Fe/NiO/MgO(001). These two different NiO spin orientations generate remarkable different effects that the NiO induced magnetic anisotropy in the Fe film is much greater in Fe/NiO/Ag(001) than in Fe/NiO/MgO(001). XMLD measurement shows that the much greater magnetic anisotropy in Fe/NiO/Ag(001) is due to a 90{sup o}-coupling between the in-plane NiO spins and the in-plane Fe spins.

  19. Effect of 200 MeV Ag+15 ion irradiation on magnetic and dielectric properties of nanocrystalline Zn-Cr ferrite

    NASA Astrophysics Data System (ADS)

    Dolia, S. N.; Pareek, S. P.; Samariya, Arvind; Sharma, P. K.; Prasad, Arun S.; Dhawan, M. S.; Kumar, Sudhish; Sharma, K. B.; Asokan, K.

    2013-08-01

    Nanocrystalline samples of ZnCr0.4Fe1.6O4 ferrite were synthesized by the advanced sol-gel method to investigate the effect of 200 MeV Ag+15 ion irradiation on the cation distribution, magnetic and dielectric properties. Rietveld profile refinement of the X-ray diffraction (XRD) patterns confirms the single-phase cubic spinel structure of the specimens. The irradiated sample retains the cubic spinel structure with a slight increase in the lattice parameters and the average crystallite size. Temperature- and field-dependent dc magnetization studies show an appreciable enhancement in the saturation magnetization and blocking temperature of the irradiated samples, which could be attributed to the slight increase in the particle size due to the heat evolved during irradiation. Subsequently, the rearrangement of cations in the lattice structure and the ion-induced modifications on the surface states of the nanoparticles could be accountable. The room temperature dielectric constant and the loss tangent in the frequency range 75 kHz-10 MHz revealed the normal frequency dispersion. The increase in ɛr and tan δ on irradiation could be attributed to the slight crystal growth and hence the availability of the sufficient number of Fe2+ and/or Zn3+ ions particularly at the octahedral site on the grain boundaries, showing a fair agreement with the magnetization results.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  1. The AGS Ggamma Meter and Calibrating the Gauss Clock

    SciTech Connect

    Ahrens, Leif

    2014-03-31

    During AGS Polarized Proton acceleration periods, one output from the AGS Ggamma Meter, namely the energy (or Ggamma) calculated from the magnetic field in the AGS main magnets and the beam radius- both measured in particular instant, is used to figure out the times in the AGS magnet acceleration cycle when the beam passes through a particular set of depolarizing resonances. The resonance set occur whenever a particle’s Ggamma (energy*(G/m) becomes nearly equal to n*Qx (i.e. any integer multiplied by the horizontal betatron tune). This deliverable is why the machinery is referred to as the ''Ggamma Meter'' rather than the AGS energy meter. The Ggamma Meter takes as inputs a set of measurements of frequency (F(t)), radius (r(t)), and gauss clock counts (GCC(t)). The other energy (GgammaBr) assumes the field when the gauss clock starts counting is known. The change in field to time t is given by the measured accumulated gauss clock counts multiplied by the gauss clock calibration (gauss/GCC). In order to deal with experimental data, this calibration factor gets an added ad hoc complication, namely a correction dependent on the rate of change the counting rate. The Ggamma meter takes GCC(t) and together with the past history for this cycle calculates B(t).

  2. Magnetic and electrical properties of Fe{sub 0.9}Ag{sub 0.1}In{sub 2.3}S{sub 4.4} single crystals

    SciTech Connect

    Bodnar, I. V.; Trukhanov, S. V.; Barugu, T. H.

    2015-10-15

    The magnetic and electrical properties of the Fe{sub 0.9}Ag{sub 0.1}In{sub 2.3}S{sub 4.4} single crystal are studied in the temperature range 4–300 K and in magnetic fields of 0–14 T. It is established that the sample under study is paramagnetic. In the ground state, short-range-order correlations typical of a spin glass with a freezing temperature of 10 K are detected. The magnetic ordering temperature is 15 K. The sample is a semiconductor with a resistivity of 3.5 kΩ cm at room temperature. For the Fe{sub 0.9}Ag{sub 0.1}In{sub 2.3}S{sub 4.4} single crystal, a mechanism for the formation of magnetic and electrical states is suggested.

  3. Magnetically separable CuFe2O4/AgBr composite photocatalysts: Preparation, characterization, photocatalytic activity and photocatalytic mechanism under visible light

    NASA Astrophysics Data System (ADS)

    Zhao, Yalei; Lin, Cuiping; Bi, Huijie; Liu, Yonggang; Yan, Qishe

    2017-01-01

    The CuFe2O4 and CuFe2O4/AgBr composites with different CuFe2O4 contents were prepared by a facile sol-gel and hydrothermal method, respectively. The as-synthesized photocatalysts were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectrum (UV-vis DRS). Their magnetic properties, photocatalytic degradation activities on methyl orange (MO) and tetracycline hydrochloride (TC) solution and photocatalytic mechanism were investigated in detail. The results revealed that the CuFe2O4/AgBr composites exhibited significantly higher photocatalytic activities than the pure CuFe2O4. The enhanced photocatalytic activity could be attributed to the matched band structure of two components and more effective charge transportation and separations. In addition, the quenching investigation of different scavengers demonstrated that h+, rad OH, rad O2- reactive species played different roles in the decolorization of MO and degradation of TC.

  4. Synthesis and magnetic structure of the layered manganese oxide selenide Sr2MnO2Ag1.5Se2

    NASA Astrophysics Data System (ADS)

    Blandy, Jack N.; Boskovic, Jelena C.; Clarke, Simon J.

    2017-01-01

    The synthesis of a high-purity sample of the layered oxide selenide Sr2MnO2Ag1.5Se2 is reported. At ambient temperature it crystallises in the space group I4/mmm with two formula units in the unit cell and lattice parameters a=4.08771(1) Å, c=19.13087(8) Å. The compound displays mixed-valent manganese in a formal oxidation state close to +2.5 and powder neutron diffraction measurements reveal that below the Néel temperature of 63(1) K this results in an antiferromagnetic structure which may be described as A-type, modelled in the magnetic space group PI4/mnc (128.410 in the Belov, Neronova and Smirnova (BNS) scheme) in which localised Mn moments of 3.99(2) μB are arranged in ferromagnetic layers which are coupled antiferromagnetically. In contrast to the isostructural compound Sr2MnO2Cu1.5S2, Sr2MnO2Ag1.5Se2 does not display long range ordering of coinage metal ions and vacancies, nor may significant amounts of the coinage metal readily be deintercalated using soft chemical methods.

  5. Design of the main racetrack microtron accelerator end magnets of the Institute of Physics of University of São Paulo

    NASA Astrophysics Data System (ADS)

    Kassab, L. R.; Martins, M. N.; Takahashi, J.; Gouffon, P.

    1999-03-01

    This work deals with the design of the Institute of Physics of the University of São Paulo (IFUSP) main racetrack microtron accelerator end magnets. This is the last stage of acceleration, comprised of an accelerating section (1.04 m) and two end magnets (0.1585 T), in which a 5.10 MeV beam, produced by a racetrack microtron booster has its energy raised up to 31.15 MeV after 28 accelerations. Poisson code was used to give the final configuration that includes auxiliary pole pieces (clamps) and auxiliary homogenizing gaps. The clamps create a reverse fringe field region and avoid the vertical defocusing and the horizontal displacement of the beam produced by extended fringe fields; Ptrace code was used to perform the trajectory calculations in the fringe field region. The auxiliary homogenizing gaps improve the field uniformity as they create a ``magnetic shower'' that provides uniformity of +/-0.3%, before the introduction of the correcting coils that will be attached to the pole faces. This method of correction, used in the IFUSP racetrack microtron booster magnets, enabled uniformity of +/-0.001% in an average field of 0.1 T and will also be employed for these end magnets.

  6. Enhanced photocatalytic activity of Ag-TiO2/Ag heterogeneous films

    NASA Astrophysics Data System (ADS)

    Liang, Ying; Wang, ShaoHua; Guo, PengFeng

    2015-11-01

    Ag-deposited TiO2 and Ag (Ag-TiO2/Ag) films coated on glass substrates were prepared using a simple sol-gel and dip-coating method. The Ag chemical state was investigated through X-ray diffractometry and X-ray photoelectron spectroscopy. Results showed that the Ag mainly exists in metallic state in the Ag-TiO2 film. Ag-TiO2/Ag exhibits higher photocatalytic activity than individual Ag-TiO2 and TiO2/Ag films. This enhanced photocatalytic activity was attributed to high surface plasmon resonance effects and separation rates of photoinduced electron-hole pairs of Ag nanoparticles. Results were verified by photoluminescence and UV-Vis spectroscopy.

  7. B2N2O4: Prediction of a Magnetic Ground State for a Light Main-Group Molecule

    SciTech Connect

    Varga, Zoltan; Truhlar, Donald G.

    2015-09-08

    Cyclobutanetetrone, (CO)4, has a triplet ground state. Here we predict, based on electronic structure calculations, that the B2N2O4 molecule also has a triplet ground state and is therefore paramagnetic; the structure is an analogue of (CO)4 in which the carbon ring is replaced by a (BN)2 ring. Similar to (CO)4, the triplet ground-state structure of B2N2O4 is also thermodynamically unstable. Besides analysis of the molecular orbitals, we found that the partial atomic charges are good indicators for predicting magnetic ground states.

  8. Novel Mn3 [Co(CN)6]2@SiO2@Ag Core-Shell Nanocube: Enhanced Two-Photon Fluorescence and Magnetic Resonance Dual-Modal Imaging-Guided Photothermal and Chemo-therapy.

    PubMed

    Wang, Dongdong; Guo, Zhen; Zhou, Jiajia; Chen, Jian; Zhao, Gaozheng; Chen, Ruhui; He, Mengni; Liu, Zhenbang; Wang, Haibao; Chen, Qianwang

    2015-11-25

    The versatile Mn3[Co(CN)6]2@SiO2@Ag core-shell NCs are prepared by a simple coprecipitation method. Ag nanoparticles with an average diameter of 12 nm deposited on the surface of Mn3[Co(CN)6]2@SiO2 through S-Ag bonding are fabricated in ethanol solution by reducing silver nitrate (AgNO3 ) with NaBH4 . The NCs possess T1 -T2 dual-modal magnetic resonance imaging ability. The inner Prussian blue analogs (PBAs) Mn3[Co(CN)6]2 exhibit bright two-photon fluorescence (TPF) imaging when excited at 730 nm. Moreover, the TPF imaging intensity displays 1.85-fold enhancement after loading of Ag nanoparticles. Besides, the sample also has multicolor fluorescence imaging ability under 403, 488, and 543 nm single photon excitation. The as-synthesized Mn3[Co(CN)6]2@SiO2@Ag NCs show a DOX loading capacity of 600 mg g(-1) and exhibit an excellent ability of near-infrared (NIR)-responsive drug release and photothermal therapy (PTT) which is induced from the relative high absorbance in NIR region. The combined chemotherapy and PTT against cancer cells in vitro test shows high therapeutic efficiency. The multimodal treatment and imaging could lead to this material a potential multifunctional system for biomedical diagnosis and therapy.

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

    SciTech Connect

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

    2005-05-30

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

  10. The Booster to AGS beam transfer fast kicker systems

    SciTech Connect

    Zhang, W.; Bunicci, J.; Soukas, A.V.; Zhang, S.Y.

    1992-08-01

    The Brookhaven AGS Booster has a very successful commissioning period in June 1991. The third phase of that commissioning was a beam extraction test. The Booster extraction fast kicker (F3) deflected a 1.2 GeV proton beam from the Booster circulating orbit into the extraction septum aperture, partially down the extraction line to a temporary beam stop. Now, the Booster is committed to the AGS operations program for both heavy ion and proton beams. Thus, the Booster extraction and the corresponding AGS injection systems must operate routinely up to a pulse repetition frequency of 7.5 Hertz, and up to a beam energy of 1.5 Gev. The injection fast kicker is located in the A5 section of the AGS ring and is used to deflect the proton or heavy ion beam into its final AGS closed orbit. A distinctive feature of the AGS injection fast kicker modulators is the tail-bitting function required for proton beam injection. This enables the system to produce a fast current fall time to go along with the high current pulse amplitude with a fast rise time. The AGS injection fast kicker system has three pulse modulators, and each modulator consists of two thyratrons. The main PFN thyratrons switch on the current, and the tail bitting thyratrons are used to force the magnet current to decrease rapidly. Two digital pulse delay generators are used to align the main thyratrons and the tail bitting thyratrons respectively. The system has been tested and installed. The final commissioning of the Booster to AGS beam transfer line and injection is currently being undertaken. In this article, the system design, realization techniques and performance data will be presented.

  11. Modeling of the corrected D st * index temporal profile on the main phase of the magnetic storms generated by different types of solar wind

    NASA Astrophysics Data System (ADS)

    Nikolaeva, N. S.; Yermolaev, Yu. I.; Lodkina, I. G.

    2015-03-01

    A modeling of the corrected (taking into account the magnetopause currents [9]) D st * index during the main phase of magnetic storms generated by four types of the solar wind (SW), namely MC (10 storms), CIR (28 storms), Sheath (21 storms), and Ejecta (31 storms), is performed similarly to our previous work on the simple D st index [8]. The "Catalog of large-scale solar wind phenomena during 1976-2000" ([1], ftp://ftp.iki.rssi.ru/pub/omni/) prepared on the basis of the OMNI database, was used for the identification of SW types. The time behavior of D st * is approximated by a linear dependence on the integral electric field (sum E y ), dynamic pressure ( P d ), and fluctuation level (s B) of the interplanetary magnetic field (IMF). Three types of D st * modeling are performed: (1) by individual values of the approximation coefficients; (2) by approximation coefficients averaged over SW type, and (3) in the same way as in (2) but with allowance for the D st *-index values preceding the beginning of the main phase of the magnetic storm. The results of modeling the corrected D st * index are compared to modeling of the usual D st index. In the conditions of a strong statistical scatter of the approximation coefficients, the use of D st instead of D st * insignificantly influences the accuracy of the modeling and correlation coefficient.

  12. Does the duration of the magnetic storm recovery phase depend on the development rate in its main phase? 2. A new method

    NASA Astrophysics Data System (ADS)

    Yermolaev, Yu. I.; Lodkina, I. G.; Nikolaeva, N. S.; Yermolaev, M. Yu.

    2016-05-01

    In contrast to our previous work (Yermolaev et al., 2015), in which we used the magnetic storm recovery phase duration, the exponential time of the recovery phase of magnetic storms generated by three interplanetary driver types (CIR, Sheath, and ICME) is introduced in the present work. The dependence of these times on the storm development rate | Dst min|/Δ T (where Δ T is the storm main phase duration) is studied. A similar physical result has been achieved despite the different data analysis method used: the times of the storm recovery and development rates correlate for storms induced by CIR and Sheath compression regions, and any relation between these parameters is absent for storms induced by ICME.

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

    DOE PAGES

    Myers, C. S.; Susner, M. A.; Miao, H.; ...

    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

  14. 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.

  15. Structural, mechanical and magnetic properties studies on high-energy Kr-ion irradiated Fe3O4 material (main corrosion layer of Fe-based alloys)

    NASA Astrophysics Data System (ADS)

    Sun, Jianrong; Wang, Zhiguang; Zhang, Hongpeng; Song, Peng; Chang, Hailong; Cui, Minghuan; Pang, Lilong; Zhu, Yabin; Li, Fashen

    2014-12-01

    The Fe-based (T91 and RAFM) alloys are considered as the promising candidate structural materials for DEMO and the first fusion power plant, and these two kinds of steels suffered more serious corrosion attack at 450 °C in liquid PbBi metal. So in order to further clarify the applicability of Fe-based structural materials in nuclear facilities, we should study not only the alloys itself but also its corrosion layers; and in order to simplify the discussion and clarify the irradiation effects of the different corrosion layer, we abstract the Fe3O4 (main corrosion layer of Fe-based alloys) to study the structural, micro-mechanical and magnetic properties under 2.03 GeV Kr-ion irradiation. The initial crystallographic structure of the Fe3O4 remains unaffected after irradiation at low damage levels, but as the Kr-ion fluence increases and the defects accumulate, the macroscopic magnetic properties (Ms, Hc, etc.) and micro-mechanical properties (nano-hardness and Young's modulus) are sensitive to high-energy Kr-ion irradiation and exhibit excruciating uniform changing regularities with varying fluences (firstly increases, then decreases). And these magnetism, hardening and softening phenomena can be interpreted very well by the effects related to the stress and defects (the production, accumulation and free) induced by high-energy ions irradiation.

  16. Multiple Partial Siberian Snakes in the AGS

    NASA Astrophysics Data System (ADS)

    Takano, J.; Ahrens, L. A.; Bai, M.; Brown, K.; Courant, E. D.; Gardner, C. J.; Glenn, J. W.; Hattori, T.; Huang, H.; Lin, F.; Luccio, A. U.; MacKay, W. W.; Okamura, M.; Roser, T.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.

    2007-06-01

    Polarized protons are accelerated up to 24.3 GeV in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). To accelerate the beam with preserving the polarization, two different types of helical dipole partial Siberian snake have been installed to the AGS. One is a superconducting magnet (Cold Snake, CSNK), and the other is a normal conducting one (Warm Snake, WSNK). With these snake magnets, the polarization at the AGS extraction achieved 65%. However, the AGS has spin mismatches at the injection and extraction. This description shows calculated results to have better spin matching with using two or three snakes.

  17. Multiple Partial Siberian Snakes in the AGS

    SciTech Connect

    Takano, J.; Ahrens, L. A.; Bai, M.; Brown, K.; Courant, E. D.; Gardner, C. J.; Glenn, J. W.; Huang, H.; Luccio, A. U.; MacKay, W. W.; Okamura, M.; Roser, T.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.; Hattori, T.; Lin, F.

    2007-06-13

    Polarized protons are accelerated up to 24.3 GeV in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). To accelerate the beam with preserving the polarization, two different types of helical dipole partial Siberian snake have been installed to the AGS. One is a superconducting magnet (Cold Snake, CSNK), and the other is a normal conducting one (Warm Snake, WSNK). With these snake magnets, the polarization at the AGS extraction achieved 65%. However, the AGS has spin mismatches at the injection and extraction. This description shows calculated results to have better spin matching with using two or three snakes.

  18. 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.

  19. Loading effect of Ag/AgO on the photocatalytic performance of ZnO rods

    NASA Astrophysics Data System (ADS)

    Samsuddin, Aida Fitri; Aziz, Siti Nor Qurratu Aini Abd; Pung, Swee-Yong

    2017-01-01

    The photocatalytic performance of ZnO rods in degradation of Rhodamine B dye under UV light was improved by 7.3% via deposition of Ag/AgO using 1.0 × 10-3 g mL-1 of silver nitrate solution. However, its photodegradation efficiency decreased with the increase in silver nitrate concentration which was used to prepare the Ag/AgO-ZnO rods. This result suggests that the loading of Ag/AgO on the surface of ZnO rods affected the photocatalytic performance differently. The scavenger study indicates that the main reactive species responsible for the degradation of Rhodamine B dye by Ag-/AgO-deposited ZnO rods were holes, followed by superoxide anion free radicals, hydroxyl free radicals and electrons. Based on these findings, a refined photodegradation mechanism of Rhodamine B by Ag/AgO-ZnO rods is proposed.

  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.

  1. Ultrasmall Magnetically Engineered Ag2Se Quantum Dots for Instant Efficient Labeling and Whole-Body High-Resolution Multimodal Real-Time Tracking of Cell-Derived Microvesicles.

    PubMed

    Zhao, Jing-Ya; Chen, Gang; Gu, Yi-Ping; Cui, Ran; Zhang, Zhi-Ling; Yu, Zi-Li; Tang, Bo; Zhao, Yi-Fang; Pang, Dai-Wen

    2016-02-17

    Cell-derived microvesicles (MVs) are natural carriers that can transport biological molecules between cells, which are expected to be promising delivery vehicles for therapeutic purposes. Strategies to label MVs are very important for investigation and application of MVs. Herein, ultrasmall Mn-magnetofunctionalized Ag2Se quantum dots (Ag2Se@Mn QDs) integrated with excellent near-infrared (NIR) fluorescence and magnetic resonance (MR) imaging capabilities have been developed for instant efficient labeling of MVs for their in vivo high-resolution dual-mode tracking. The Ag2Se@Mn QDs were fabricated by controlling the reaction of Mn(2+) with the Ag2Se nanocrystals having been pretreated in 80 °C NaOH solution, with an ultrasmall size of ca. 1.8 nm, water dispersibility, high NIR fluorescence quantum yield of 13.2%, and high longitudinal relaxivity of 12.87 mM(-1) s(-1) (almost four times that of the commercial contrast agent Gd-DTPA). The ultrasmall size of the Ag2Se@Mn QDs enables them to be directly and efficiently loaded into MVs by electroporation, instantly and reliably conferring both NIR fluorescence and MR traceability on MVs. Our method for labeling MVs of different origins is universal and free of unfavorable influence on intrinsic behaviors of MVs. The complementary imaging capabilities of the Ag2Se@Mn QDs have made the long-term noninvasive whole-body high-resolution dual-mode tracking of MVs in vivo realized, by which the dynamic biodistribution of MVs has been revealed in a real-time and in situ quantitative manner. This work not only opens a new window for labeling with QDs, but also facilitates greatly the investigation and application of MVs.

  2. Status of the Alternating Gradient Synchrotron (AGS) upgrade project

    SciTech Connect

    Sluyters, T.

    1988-01-01

    The upgrade of BNL's Alternating Gradient Synchrotron progresses parallel with the construction of the 1.5 GeV Booster with a view to completion of its major components in 1991. The initial goals of the upgrade program are: to prepare the AGS ring for acceleration of at least 5 /times/ 10/sup 13/ protons per pulse, to accelerate heavy ions up to gold, to accelerate polarized protons in the 10/sup 12/-10/sup 13/ intensity range, and to improve the reliability and flexibility of the present machine operation. Figure 1 shows the AGS complex as it will operate in 1991. There are several major systems in the AGS complex which have to be upgraded in order to accelerate the higher intensity beams and heavier ions. These systems are: the RFQ preinjector, the rf cavities, the vacuum, the transverse dampers, the correction magnets, extraction equipment, and the Siemens main magnet power supply. Additional major projects, which will keep the ring activation within /open quotes/acceptable/close quotes/ limits despite a four-fold increase in beam intensity, are a fast beam chopper, a gamma-transition jump system, and a high frequency dilution cavity. These last projects have received high priority because they benefit as well the present operation of the AGS.

  3. The AGS new fast extraction system for the g-2 experiment and RHIC injection

    SciTech Connect

    Tanaka, M.; Lee, Y.Y.

    1991-01-01

    The AGS requires a new fast extraction beam (NewFEB) system for the muon g-2 experiment and the Relativistic Heavy Ion Collider (RHIC). The proposed NewFEB system will consist of a new fast multi-pulsing kicker placed at straight section G10 and an ejector septum magnet at H10, together will local orbit bumps generated by powering backleg windings on the AGS main magnets. The new system is capable of performing single bunch multiple extraction as often as every 8 ms up to 12 times per AGS cycle, in addition to the standard single turn fast extraction. The conceptual design of the NewFEB system will be discussed. 3 refs., 3 figs., 1 tab.

  4. Variations of the ionospheric plasma concentration in the region of the main ionospheric trough during the magnetic storm of December 18-19, 1978, in connection with measurements of the interplanetary magnetic field

    SciTech Connect

    Gdalevich, G.L.; Afonin, V.V.; Eliseev, A.Y.; Kolomiitsev, O.P.; Ozerov, V.D.; Soboleva, T.N.

    1986-07-01

    Data from the Kosmos-900 satellite are used to examine variations of the ion concentration in the region of the main ionospheric trough at altitudes of about 500 km during the storm of December 18-19, 1978. These variations of ion densities are compared with the variations of the parameters of the interplanetary medium, in particular, with the E /sub y/ = -VB /sub z/ component of the interplanetary electric field. The results of the comparison are discussed. A scheme is proposed for the formation and motion of the trough during magnetic disturbances.

  5. A visible-light-driven core-shell like Ag2S@Ag2CO3 composite photocatalyst with high performance in pollutants degradation.

    PubMed

    Yu, Changlin; Wei, Longfu; Zhou, Wanqin; Dionysiou, Dionysios D; Zhu, Lihua; Shu, Qing; Liu, Hong

    2016-08-01

    A series of Ag2S-Ag2CO3 (4%, 8%, 16%, 32% and 40% Ag2S), Ag2CO3@Ag2S (32%Ag2S) and Ag2S@Ag2CO3 (32%Ag2S) composite photocatalysts were fabricated by coprecipitation or successive precipitation reaction. The obtained catalysts were analyzed by N2 physical adsorption, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and photocurrent test. Under visible light irradiation, the influences of Ag2S content and core-shell property on photocatalytic activity and stability were evaluated in studies focused on the degradation of methyl orange (MO) dye, phenol, and bisphenol A. Results showed that excellent photocatalytic performance was obtained over Ag2S/Ag2CO3 composite photocatalysts with respect to Ag2S and Ag2CO3. With optimal content of Ag2S (32 wt%), the Ag2S-Ag2CO3 showed the highest photocatalytic degradation efficiency. Moreover, the structured property of Ag2S/Ag2CO3 greatly influenced the activity. Compared with Ag2S-Ag2CO3 and Ag2CO3@Ag2S, core-shell like Ag2S@Ag2CO3 demonstrated the highest activity and stability. The main reason for the boosting of photocatalytic performance was due to the formation of Ag2S/Ag2CO3 well contacted interface and unique electron structures. Ag2S/Ag2CO3 interface could significantly increase the separation efficiency of the photo-generated electrons (e(-)) and holes (h(+)), and production of OH radicals. More importantly, the low solubility of Ag2S shell could effectively protect the core of Ag2CO3, which further guarantees the stability of Ag2CO3.

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

    PubMed

    Yantasee, Wassana; Hongsirikarn, Kitiya; Warner, Cynthia L; Choi, Daiwon; Sangvanich, Thanapon; Toloczko, Mychailo B; Warner, Marvin G; Fryxell, Glen E; Addleman, R Shane; Timchalk, Charles

    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. Detection of metal ions in urine has been problematic due to the protein competition and electrode fouling. 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 90 s of preconcentration in samples containing 25 vol.% of rat urine and 0.1 g L(-1) of DMSA-Fe3O4, the sensor could detect background level of Pb (0.5 ppb) and yielded linear responses from 0 to 50 ppb of Pb, excellent reproducibility (%RSD 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.

  7. Experimental study of loss mechanisms of AgAu/PbBi-2223 tapes with twisted filaments under perpendicular AC magnetic fields at power frequencies

    NASA Astrophysics Data System (ADS)

    Martínez, E.; Yang, Y.; Beduz, C.; Huang, Y. B.

    2000-05-01

    AC losses under perpendicular AC fields have been measured at 77 K and power frequencies for multifilamentary AgAu (10 wt.%)/Bi-2223 tapes with filaments twisted at different pitches. Using simultaneous measurements of the first and higher harmonics of the voltage induced in the pick-up coil, the main loss contributions (superconductor and coupling current losses) have been obtained separately. At power frequencies, twisting produces the desired uncoupling of the filaments at fields lower than the coupling field, which has also been determined experimentally. In the uncoupled-filament regime, the superconductor losses are reduced strongly with respect to the untwisted tapes. The reduction of the total loss with twisting is also observed. However, due to the important contribution of the coupling current losses for this field orientation, a very small pitch (<5 mm) is necessary for a considerably lower loss than that of untwisted tapes. The dependence of the coupling field and coupling current losses on the twist pitch has been analysed and compared with the theoretical predictions.

  8. Statistical Analysis of Main and Interaction Effects on Cu(II) and Cr(VI) Decontamination by Nitrogen–Doped Magnetic Graphene Oxide

    NASA Astrophysics Data System (ADS)

    Hu, Xinjiang; Wang, Hui; Liu, Yunguo

    2016-10-01

    A nitrogen–doped magnetic graphene oxide (NMGO) was synthesized and applied as an adsorbent to remove Cu(II) and Cr(VI) ions from aqueous solutions. The individual and combined effects of various factors (A: pH, B: temperature, C: initial concentration of metal ions, D: CaCl2, and E: humic acid [HA]) on the adsorption were analyzed by a 25‑1 fractional factorial design (FFD). The results from this study indicated that the NMGO had higher adsorption capacities for Cu(II) ions than for Cr(VI) ions under most conditions, and the five selected variables affected the two adsorption processes to different extents. A, AC, and C were the very important factors and interactions for Cu(II) adsorption. For Cr(VI) adsorption, A, B, C, AB, and BC were found to be very important influencing variables. The solution pH (A) was the most important influencing factor for removal of both the ions. The main effects of A–E on the removal of Cu(II) were positive. For Cr(VI) adsorption, the main effects of A and D were negative, while B, C, and E were observed to have positive effects. The maximum adsorption capacities for Cu(II) and Cr(VI) ions over NMGO were 146.365 and 72.978 mg/g, respectively, under optimal process conditions.

  9. Statistical Analysis of Main and Interaction Effects on Cu(II) and Cr(VI) Decontamination by Nitrogen–Doped Magnetic Graphene Oxide

    PubMed Central

    Hu, Xinjiang; Wang, Hui; Liu, Yunguo

    2016-01-01

    A nitrogen–doped magnetic graphene oxide (NMGO) was synthesized and applied as an adsorbent to remove Cu(II) and Cr(VI) ions from aqueous solutions. The individual and combined effects of various factors (A: pH, B: temperature, C: initial concentration of metal ions, D: CaCl2, and E: humic acid [HA]) on the adsorption were analyzed by a 25−1 fractional factorial design (FFD). The results from this study indicated that the NMGO had higher adsorption capacities for Cu(II) ions than for Cr(VI) ions under most conditions, and the five selected variables affected the two adsorption processes to different extents. A, AC, and C were the very important factors and interactions for Cu(II) adsorption. For Cr(VI) adsorption, A, B, C, AB, and BC were found to be very important influencing variables. The solution pH (A) was the most important influencing factor for removal of both the ions. The main effects of A–E on the removal of Cu(II) were positive. For Cr(VI) adsorption, the main effects of A and D were negative, while B, C, and E were observed to have positive effects. The maximum adsorption capacities for Cu(II) and Cr(VI) ions over NMGO were 146.365 and 72.978 mg/g, respectively, under optimal process conditions. PMID:27694891

  10. A study on the main periodicities in interplanetary magnetic field Bz component and geomagnetic AE index during HILDCAA events using wavelet analysis

    NASA Astrophysics Data System (ADS)

    Souza, A. M.; Echer, E.; Bolzan, M. J. A.; Hajra, R.

    2016-11-01

    The interplanetary and geomagnetic characteristics of High-Intensity Long-Duration Continuous AE Activity (HILDCAA) events are studied using wavelet analysis technique. The Morlet wavelet transform was applied to the 1 min interplanetary magnetic field (IMF) Bz component and the geomagnetic AE index during HILDCAA events. We have analyzed the AE data for the events occurring between 1975 and 2011, and the IMF Bz data (both in GSE and GSM) for the events between 1995 and 2011. We analyzed the scalograms and the global wavelet spectrum of the parameters. For 50% of all HILDCAA events, the main periodicities of the AE index are generally between 4 and 12 h. For the Bz component, the main periodicities were found to be less than 8 h for 56% of times in GSM system and for 54% of times in GSE system. It is conjectured that the periodicities might be associated with the Alfvén waves which have typical periods between 1 and 10 h. The results are discussed in the light of self organized criticality theory where the physical events have the capacity of releasing a considerable amount of energy in a short interval of time.

  11. Electronic structures and magnetism in the Li2AgSb-type Heusler alloys, Zr2CoZ (Z=Al, Ga, In, Si, Ge, Sn, Pb, Sb): A first-principles study

    NASA Astrophysics Data System (ADS)

    Wang, X. T.; Cui, Y. T.; Liu, X. F.; Liu, G. D.

    2015-11-01

    The electronic and magnetic properties of Zr2CoZ (Z=Al, Ga, In, Si, Ge, Sn, Pb, and Sb) alloys with a Li2AgSb-type structure were investigated systematically using the first-principle calculations. Zr2CoZ (Z=Al, Ga, In, Si, Ge, Sn, and Pb) alloys are predicted to be half-metallic ferromagnets at their equilibrium lattice constants. The Zr2Co-based alloys have Mt (the total magnetic moment per unit cell) and Zt (the valence concentration) values following Slater-Pauling rule of Mt=Zt-18. The effects of lattice constants on the electronic and the magnetic properties are discussed in detail. Moreover, all the alloys investigated in this paper have a negative formation energy, which implies that they are thermodynamically stable.

  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. Tunable and enhanced SERS activity of magneto-plasmonic Ag-Fe3O4 nanocomposites with one pot synthesize method

    NASA Astrophysics Data System (ADS)

    Fan, Chunzhen; Zhu, Shuangmei; Xin, Haoyi; Tian, Yuchen; Liang, Erjun

    2017-01-01

    In this paper, we report the tunable and enhanced SERS activity of magneto-plasmonic Ag-Fe3O4 nanocomposites that are synthesized by a one pot method. Crystal violet (CV), rhodamine 6 G (R6G) and 4-mercaptobenzoic acid (4-MBA) molecules are used to investigate the SERS optical activity of Ag-Fe3O4 nanocomposites under different external magnetic fields (1500, 2000, 2500, 3500 and 5000 gauss). The experimental results demonstrate the enhanced Raman effects that can be obtained by increasing the magnitude of external magnetic field. This is because the electromagnetic hot spots located between the neighboring Ag-Fe3O4 nanocomposites can be tuned by utilizing the external magnetic field. The bigger density of the hot-spots and amplitude of the electric field in the hot-spot are responsible for the enhanced SERS effect. The detection limit of CV molecule can be at least down to 10-9 M. The spectra measurements of hemoglobin adsorbed on the Ag-Fe3O4 nanocomposites under different external magnetic fields are also performed to explore its bio-applications. Finite element method (FEM) is used to simulate the local electromagnetic field distribution in Ag-Fe3O4 nanocomposites, revealing the SERS enhanced mechanism is determined mainly by the near field enhanced electromagnetic field. Due to its tunable and enhanced properties, Ag-Fe3O4 nanocomposites are expected to be promising SERS substrates for chemical and biological sensing applications.

  14. One-pot synthesis of ternary Ag₂CO₃/Ag/AgCl photocatalyst in natural geothermal water with enhanced photocatalytic activity under visible light irradiation.

    PubMed

    Yao, Xiaxi; Liu, Xiaoheng

    2014-09-15

    Geothermal water is a clean, cheap and renewable resource and it is widely distributed all over the world. In this work, ternary Ag2CO3/Ag/AgCl photocatalyst has been successfully synthesized via a one-pot precipitation method in natural geothermal water at room temperature, wherein the geothermal water serves as the source of chlorine and carbonate. The results suggest that the Ag/AgCl nanoparticles are anchored on the surface of Ag2CO3 and Ag2CO3/Ag/AgCl composite shows strong absorption ability in the visible light region. The evaluation of the photocatalytic activity indicates that the as-synthesized Ag2CO3/Ag/AgCl photocatalyst exhibits higher photocatalytic performance for the degradation of methylene blue (MB) aqueous solution under visible light irradiation than one-component (Ag2CO3), two-component (Ag/AgCl, Ag2CO3/AgCl) and the mechanical mixture of Ag2CO3 and Ag/AgCl. The trapping experiments confirmed that holes (h(+)) and (•)O2(-) were the two main active species in the photocatalytic process. Finally, a possible Z-scheme photocatalytic mechanism of the charge transfer was proposed for the enhanced photocatalytic performance. This work may open up new insights into the application of cheap geothermal water resources in the word and provide new opportunities for facile fabrication of Ag/AgCl-based photocatalysts.

  15. Accretion and Magnetic Reconnection in the Pre-Main Sequence Binary DQ Tau as Revealed through High-Cadence Optical Photometry

    NASA Astrophysics Data System (ADS)

    Tofflemire, Benjamin M.; Mathieu, Robert D.; Ardila, David R.; Akeson, Rachel L.; Ciardi, David R.; Herczeg, Gregory; Johns-Krull, Christopher M.; Vodniza, Alberto

    2016-01-01

    Protostellar disks are integral to the formation and evolution of low-mass stars and planets. A paradigm for the star-disk interaction has been extensively developed through theory and observation in the case of single stars. Most stars, however, form in binaries or higher order systems where the distribution of disk material and mass flows are more complex. Pre-main sequence (PMS) binary stars can have up to three accretion disks: two circumstellar disks and a circumbinary disk separated by a dynamically cleared gap. Theory suggests that mass may periodically flow in an accretion stream from a circumbinary disk across the gap onto circumstellar disks or stellar surfaces.The archetype for this theory is the eccentric, PMS binary DQ Tau. Moderate-cadence broadband photometry (~10 observations per orbital period) has shown pulsed brightening events near most periastron passages, just as numerical simulations would predict for a binary of similar orbital parameters. While this observed behavior supports the accretion stream theory, it is not exclusive to variable accretion rates. Magnetic reconnection events (flares) during the collision of stellar magnetospheres at periastron (when separated by 8 stellar radii) could produce the same periodic, broadband behavior when observed at a one-day cadence. Further evidence for magnetic activity comes from gyrosynchrotron, radio flares (typical of stellar flares) observed near multiple periastron passages. To reveal the physical mechanism seen in DQ Tau's moderate-cadence observations, we have obtained continuous, moderate-cadence, multi-band photometry over 10 orbital periods (LCOGT 1m network), supplemented with 32 nights of minute-cadence photometry centered on 4 separate periastron passages (WIYN 0.9m; APO ARCSAT). With detailed lightcurve morphologies we distinguish between the gradual rise and fall on multi-day time-scales predicted by the accretion stream theory and the hour time-scale, rapid-rise and exponential

  16. The effect of the time dependent angular distribution of the intergrain magnetic field on the transport critical current in Ag-(Bi,Pb)2Sr2Ca2Cu3Ox tapes

    NASA Astrophysics Data System (ADS)

    Glowacki, B. A.; Noji, H.; Oota, A.

    1996-08-01

    Changes in the energy dissipation of the tape form Ag-(Bi,Pb)2Sr2Ca2Cu3Ox conductor have been interpreted in terms of magnetic flux movement from, or into, the intergrain regions of the highly textured plate like grain structure. The time dependent increase or decrease of the transport critical current (Ic), originates from time dependent angular superposition of the current induced self field (HSF), and external magnetic field [field cooling (HFC), and zero-field cooling (HZFC)] at the intergrain regions. The existence of time dependent changes of Ic can be explained in terms of the time dependent flux redistribution in grains and grain boundaries caused by thermal relaxation processes.

  17. AGS tune jump power supply design and test

    SciTech Connect

    Mi, J.; Glenn, J.W.; Huang, H.; Marneris, I.; Rosas, P.; Sandberg, J.; Tan, Y.; Zhang, W.

    2011-03-28

    A horizontal tune jump system has been installed to overcome the horizontal intrinsic spin resonances, which requires jumping the horizontal tune 0.04 units 82 times, 41 up and 41 down. Two quadruple magnets have been installed in AGS ring to perform this. The pulsed magnet current ranges from about 140A near injection to about 1400A later. The current pulse rise and fall time are around 100uS and flat tops time is around 4mS. These quadruples have separated supplies. This tune jump pulse power supply employees all semiconductor parts as well as the main switches. During dummy load and magnet testing, the test results showed that the power supply could meet the specification. This article will describe some details of power supply simulation, design and testing. Some test waveforms and pictures are presented in this paper.

  18. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Characterization of Ag adsorption on TiC(001) substrate: an ab initio study

    NASA Astrophysics Data System (ADS)

    Ma, Shang-Yi; Wang, Shao-Qing

    2008-10-01

    Ag adsorptions at 0.25-3 monolayer (ML) coverage on a perfect TiC(001) surface and at 0.25 ML coverage on C vacancy are separately investigated by using the pseudopotential-based density functional theory. The preferential adsorption sites and the adsorption-induced modifications of electronic structures of both the substrate and adsorbate are analysed. Through the analyses of adsorption energy, ideal work of separation, interface distance, projected local density of states, and the difference electron density, the characteristic evolution of the adatom-surface bonding as a function of the amount of deposited silver is studied. The nature of the Ag/TiC bonding changes as the coverage increases from 0.25 to 3 MLs. Unlike physisorption in an Ag/MgO system, polar covalent component contributes to the Ag/TiC interfacial adhesion in most cases, however, for the case of 1-3 ML coverage, an additional electrostatic interaction between the absorption layer and the substrate should be taken into account. The value of ideal work of separation, 1.55 J/m2 for a 3-ML-thick adlayer accords well with other calculations. The calculations predict that Ag does not wet TiC(001) surface and prefers a three-dimensional growth mode in the absence of kinetic factor. This work reports on a clear site and coverage dependence of the measurable physical parameters, which would benefit the understanding of Ag/TiC (001) interface and the analysis of experimental data.

  19. Helical dipole partial Siberian snake for the AGS

    NASA Astrophysics Data System (ADS)

    Takano, J.; Ahrens, L. A.; Alforque, R.; Bai, M.; Brown, K.; Courant, E. D.; Ganetis, G.; Gardner, C. J.; Glenn, J. W.; Hattori, T.; Huang, H.; Jain, A.; Luccio, A. U.; MacKay, W. W.; Okamura, M.; Roser, T.; Tsoupas, N.; Tepikian, S.; Tuozzolo, J.; Wood, J.; Zelenski, A.; Zeno, K.

    2006-11-01

    Overcoming depolarization resonances in medium class synchrotrons (3 to 50 GeV) is one of the key issues in accelerating a highly polarized proton beam up to very high energies. Since such synchrotrons, including the Alternating Gradient Synchrotron (AGS) and the J-PARC Main Ring, generally do not have sufficiently long straight sections to accommodate full Siberian snakes with reasonable beam excursions, the practical solution is to use partial Siberian snakes that rotate the particle spin about a horizontal axis by a fraction of 180 degrees. For the AGS, we designed and installed a new partial Siberian snake consisting of a helical dipole magnet with a double pitch structure. The helical structure reduced the amount of transverse coupling as compared to that achieved by the previous solenoidal partial snake. This coupling led to partial depolarization at certain energies from horizontal betatron oscillations. The helical magnetic field in the snake magnet was calculated using a 3D magnetic field code TOSCA, and was optimized by segmenting the helical pitch and varying the lengths of the segments. Fabrication errors were checked and verified to be within required tolerances. Finally, the transverse field was measured by rotating harmonic coils. After installation, we achieved a 37.5% improvement in polarization - from 40% with the old solenoid to 55% with the new helical snake, thereby demonstrating that the helical partial snake is an effective device to suppress depolarization resonances in medium-sized synchrotrons.

  20. A simple crunching of the AGS 'bare' machine ORM data - February 2007 - to extract some aspects of AGS transverse coupling at injection and extraction

    SciTech Connect

    Ahrens, L.

    2010-11-01

    The objective of this note is to (once again) explore the AGS 'ORM' (orbit response matrix) data taken (by Operations) early during the 2007 run with an AGS bare machine and gold beam. Indeed the present motivation is to extract as much information about the AGS inherent transverse coupling as possible - from general arguments and the copious ORM data. And taking this one step further, (though not accomplished yet) the goal really should be to tell the model how to describe this coupling. 'Bare' as used here means the AGS with no quadrupole, sextupole or octupole magnets powered. Only the main (combined-function) magnet string and dipole bumps necessary to optimize beam survival are powered. 'ORM data' means the systematic recording of the equilibrium orbit beam position monitor response to powering individual dipole corrector magnets. The 'matrix' results from looking at the effect of each of the (12 superperiods X 4 dipoles per superperiod) 'kicks' on each of the (12 X 6) pick up electrodes (pues) in each transverse plane. So then we have two (48 X 72) matrices of numbers from the ORM data. (Though 'pue' usually refers to the hardware in the vacuum chamber and 'bpm' to the beam position monitoring system, the two labels will be used casually here.) The exercise is carried out at two magnet rigidities, injection (AGS field {approx}434 Gauss) and extraction to RHIC ({approx}9730 Gauss), - a ratio of rigidities of about 22.4. Since we stick with a bare machine, we are also stuck with the bare tunes which means the tunes are rather close together and near 8.75. Injection: (h,v) {approx} (8.73, 8.76).

  1. Capillary electrophoresis with online stacking in combination with AgNPs@MCM-41 reinforced hollow fiber solid-liquid phase microextraction for quantitative analysis of Capecitabine and its main metabolite 5-Fluorouracil in plasma samples isolated from cancer patients.

    PubMed

    Forough, Mehrdad; Farhadi, Khalil; Molaei, Rahim; Khalili, Hedayat; Shakeri, Ramin; Zamani, Asghar; Matin, Amir Abbas

    2017-01-01

    The purpose of this study is the development and validation of a simple, novel, selective and fast off-line microextraction technique combining capillary electrophoresis with in-column field-amplified sample injection (FASI) for the simultaneous determination of capecitabine (CAP) and its active metabolite, 5-Fluorouracil (5-FU), in human plasma. At the moment, there is a lack of using cost-effective CE tool combined with novel miniaturized sample clean-up techniques for analysis of these important anti-cancer agents in plasma samples. This paper intends to fill this gap and describe a simple off-line sample pretreatment by means of AgNPs@MCM-41 reinforced hollow fiber Solid/Liquid phase microextraction (AgNPs@MCM41-HF-SLPME) with subsequent quantitation by FASI-CE. The separation of analytes was performed using a BGE containing 60mM phosphate-Tris buffer (pH 7) with 10% methanol as an organic modifier. Before sample loading, a short water plug (50mbar, 3s) was injected to permit FASI for stacking. Various parameters affecting the off-line microextraction efficiency as well as FASI were optimized. Migration time was found to be 6.6 (±0.1)min for 5-FU and 7.4 (±0.2)min for CAP. The linearity, precision, accuracy, recovery, selectivity, specificity, stability as well as the robustness of the method was evaluated from spiked plasma samples during the course of validation. The results revealed that the presented technique demonstrates acceptable accuracy and precision, miniaturized sample preparation and a reduced need for complicated equipment along with an acceptable analysis time. The validated method was successfully applied to determine CAP and 5-FU in patient's plasma samples.

  2. Processing and characterization of superconducting solenoids made of Bi-2212/Ag-alloy multifilament round wire for high field magnet applications

    NASA Astrophysics Data System (ADS)

    Chen, Peng

    As the only high temperature superconductor with round wire (RW) geometry, Bi2Sr2CaCu2O8+x (Bi-2212) superconducting wire has the advantages of being multi-filamentary, macroscopically isotropic and twistable. With overpressure (OP) processing techniques recently developed by our group at the National High Magnetic Field Laboratory (NHMFL), the engineering current density (Je) of Bi-2212 RW can be dramatically increased. For example, Je of more than 600 A/mm 2 (4.2 K and 20 T) is achieved after 100 bar OP processing. With these intrinsically beneficial properties and recent processing progress, Bi-2212 RW has become very attractive for high field magnet applications, especially for nuclear magnetic resonance (NMR) magnets and accelerator magnets etc. This thesis summarizes my graduate study on Bi-2212 solenoids for high field and high homogeneity NMR magnet applications, which mainly includes performance study of Bi-2212 RW insulations, 1 bar and OP processing study of Bi-2212 solenoids, and development of superconducting joints between Bi-2212 RW conductors. Electrical insulation is one of the key components of Bi-2212 coils to provide sufficient electrical standoff within coil winding pack. A TiO 2/polymer insulation offered by nGimat LLC was systematically investigated by differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), dielectric property measurements, and transport critical current (Ic) property measurements. About 29% of the insulation by weight is polymer. When the Bi-2212 wire is fully heat treated, this decomposes with slow heating to 400 °C in flowing O2. After the full reaction, we found that the TiO2 did not degrade the critical current properties, adhered well to the conductor, and provided a breakdown voltage of more than 100 V. A Bi-2212 RW wound solenoid coil was built using this insulation being offered by nGimat LLC. The coil resistance was constant through coil winding, polymer burn

  3. Ion-exchange synthesis of Ag/Ag2S/Ag3CuS2 ternary hollow microspheres with efficient visible-light photocatalytic activity.

    PubMed

    Xing, Chaosheng; Zhang, Yuan; Wu, Zhudong; Jiang, Deli; Chen, Min

    2014-02-21

    Ternary Ag/Ag2S/Ag3CuS2 hollow microspheres were synthesized via an in situ ion-exchange method using Cu7S4 hollow submicrospheres as the template. The as-obtained Ag/Ag2S/Ag3CuS2 composite exhibited a well-defined uniform hollow microsphere morphology with an average diameter of about 1.3 μm. The photocatalytic property of the as-prepared Ag/Ag2S/Ag3CuS2 hollow microsphere composite was investigated by the decomposition of methyl orange (MO) under visible light irradiation (λ > 420 nm). It was shown that the photocatalytic activity of the Ag/Ag2S/Ag3CuS2 hollow microsphere was higher than those of Ag/Ag2S, Cu2O, Cu7S4 and P25 for the photodegradation of MO under visible light irradiation. Radical scavenger experiments demonstrated that superoxide radicals and holes were the main reactive species for MO degradation.

  4. Three-dimensional simulations of near-surface convection in main-sequence stars. IV. Effect of small-scale magnetic flux concentrations on centre-to-limb variation and spectral lines

    NASA Astrophysics Data System (ADS)

    Beeck, B.; Schüssler, M.; Cameron, R. H.; Reiners, A.

    2015-09-01

    Context. Magnetic fields affect the local structure of the photosphere of stars. They can considerably influence the radiative properties near the optical surface, flow velocities, and the temperature and pressure profiles. This has an impact on observables such as limb darkening and spectral line profiles. Aims: We aim at understanding qualitatively the influence of small magnetic flux concentrations in unipolar plage regions on the centre-to-limb variation of the intensity and its contrast and on the shape of spectral line profiles in cool main-sequence stars. Methods: We analyse the bolometric and continuum intensity and its angular dependence of 24 radiative magnetohydrodynamic simulations of the near-surface layers of main-sequence stars with six different sets of stellar parameters (spectral types F to early M) and four different average magnetic field strengths (including the non-magnetic case). We also calculated disc-integrated profiles of three spectral lines. Results: The small magnetic flux concentrations formed in the magnetic runs of simulations have a considerable impact on the intensity and its centre-to-limb variation. In some cases, the difference in limb darkening between magnetic and non-magnetic runs is larger than the difference between the spectral types. Spectral lines are not only broadened owing to the Zeeman effect, but are also strongly affected by the modified thermodynamical structure and flow patterns. This indirect magnetic impact on the line profiles is often bigger than that of the Zeeman effect. Conclusions: The effects of the magnetic field on the radiation leaving the star can be considerable and is not restricted to spectral line broadening and polarisation by the Zeeman effect. The inhomogeneous structure of the magnetic field on small length scales and its impact on (and spatial correlation with) the local thermodynamical structure and the flow field near the surface influence the measurement of the global field properties

  5. Strain control of composite superconductors to prevent degradation of superconducting magnets due to a quench: I. Ag/Bi2Sr2CaCu2Ox multifilament round wires

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    The critical current of many practical superconductors is sensitive to strain, and this sensitivity is exacerbated during a quench that induces a peak local strain which can be fatal to superconducting magnets. Here, a new method is introduced to quantify the influence of the conductor stress and strain state during normal operation on the margin to degradation during a quench, as measured by the maximum allowable hot spot temperature T allowable, for composite wires within superconducting magnets. The first conductor examined is Ag-sheathed Bi2Sr2CaCu2Ox round wire carrying high engineering critical current density, J E, of 550 A mm-2 at 4.2 K and 15 T. The critical axial tensile stress of this conductor is determined to be 150 MPa and, in the absence of Lorentz forces, T allowable is greater than 450 K. With increasing axial tensile stress, σ a, however, T allowable decreases nonlinearly, dropping to 280 K for σ a = 120 MPa and to 160 K for σ a = 145 MPa. T allowable(σ a) is shown to be nonlinear and independent of magnetic field from 15 to 30 T. T allowable(σ a) dictates the balance between magnetic field generation, which increases with the magnet operating current and stress, and the safety margin, which decreases with decreasing T allowable, and therefore has important engineering value. It is also shown that T allowable(σ a) can be predicted accurately by a general strain model, showing that strain control is the key to preventing degradation of superconductors during a quench.

  6. Nanoparticles affect PCR primarily via surface interactions with PCR components: using amino-modified silica-coated magnetic nanoparticles as a main model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nanomaterials have been widely reported to affect the polymerase chain reaction (PCR). However, many studies in which these effects were observed were not comprehensive, and many of the proposed mechanisms have been primarily speculative. In this work, we used amino-modified silica-coated magnetic n...

  7. Inorganic anion-dependent assembly of zero-, one-, two- and three-dimensional Cu(II)/Ag(I) complexes under the guidance of the HSAB theory: Synthesis, structure, and magnetic property

    NASA Astrophysics Data System (ADS)

    Liu, Yaru; Xing, Zhiyan; Zhang, Xiao; Liang, Guorui

    2017-02-01

    To systematically explore the influence of inorganic anions on building coordination complexes, five novel complexes based on 1-(benzotriazole-1-methyl)-2-propylimidazole (bpmi), [Cu(bpmi)2(Ac)2]·H2O (1), [Cu(bpmi)2(H2O)2]·2NO3·2H2O (2), [Cu(bpmi)(N3)2] (3), [Ag(bpmi)(NO3)] (4) and [Cu3(bpmi)2(SCN)4(DMF)] (5) (Ac-=CH3COO-, DMF=N,N-Dimethylformamide) are synthesized through rationally introducing Cu(II) salts and Ag(I) salt with different inorganic anions. X-ray single-crystal analyses reveal that these complexes show interesting structural features from mononuclear (1), one-dimensional (2 and 3), two-dimensional (4) to three-dimensional (5) under the influence of inorganic anions with different basicities. The structural variation can be explained by the hard-soft-acid-base (HSAB) theory. Magnetic susceptibility measurement indicates that complex 3 exhibits an antiferromagnetic coupling between adjacent Cu(II) ions.

  8. Ag-Fe2O3 nanocomposites with enhanced catalytic activity for reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Liu, Shiben; Chen, Yingjie; Dong, Lifeng

    2016-07-01

    Hybrid nanostructures can be multifunctional and even possess enhanced properties. Ag-Fe2O3 nanocomposites and Ag nanoparticles (NPs) were fabricated and applied to catalyze the reduction of 4-nitrophenol. Compared with Ag NPs, Ag-Fe2O3 nanocomposites demonstrated enhanced catalytic activities. Furthermore, due to their magnetic properties, Ag-Fe2O3 nanocomposites could be easily separated from the reaction mixture and recycled through an external magnetic field. These findings will help us design hybrid nanostructures with catalytic activity and explore other potential applications of magnetic nanocomposites.

  9. Main Group Metal-Actinide Magnetic Coupling and Structural Response Upon U(4+) Inclusion Into Bi, Tl/Bi, or Pb/Bi Cages.

    PubMed

    Lichtenberger, Niels; Wilson, Robert J; Eulenstein, Armin R; Massa, Werner; Clérac, Rodolphe; Weigend, Florian; Dehnen, Stefanie

    2016-07-27

    The encapsulation of actinide ions in intermetalloid clusters has long been proposed but was never realized synthetically. We report the isolation and experimental, as well as quantum chemical, characterization of the uranium-centered clusters [U@Bi12](3-), [U@Tl2Bi11](3-), [U@Pb7Bi7](3-), and [U@Pb4Bi9](3-), upon reaction of (EE'Bi2)(2-) (E = Ga, Tl, E' = Bi; E = E' = Pb) and [U(C5Me4H)3] or [U(C5Me4H)3Cl] in 1,2-diaminoethane. For [U@Bi12](3-), magnetic susceptibility measurements rationalize an unprecedented antiferromagnetic coupling between a magnetic U(4+) site and a unique radical Bi12(7-) shell.

  10. Main Design Principles of the Cold Beam Pipe in the FastRamped Superconducting Accelerator Magnets for Heavy Ion Synchrotron SIS100

    NASA Astrophysics Data System (ADS)

    Mierau, A.; Schnizer, P.; Fischer, E.; Macavei, J.; Wilfert, S.; Koch, S.; Weiland, T.; Kurnishov, R.; Shcherbakov, P.

    SIS100, the world second large scale heavy ion synchrotron using fast ramped superconducting magnets, is to be built at FAIR. Its high current operation of intermediate charge state ions requires stable vacuum pressures < 10-12 mbar under dynamic machine conditions which are only achievable when the whole beam pipe is used as an huge cryopump. In order to find technological feasible design solutions, three opposite requirements have to be met: minimum magnetic field distortion caused by AC losses, mechanical stability and low and stable wall temperatures of the beam pipe. We present the possible design versions of the beam pipe for the high current curved dipole. The pros and cons of these proposed designs were studied using simplified analytical models, FEM calculations and tests on models.

  11. 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.

  12. Preparation of Ag2O/Ag2CO3/MWNTs composite photocatalysts for enhancement of ciprofloxacin degradation

    NASA Astrophysics Data System (ADS)

    Wang, Huiqin; Li, Jinze; Huo, Pengwei; Yan, Yongsheng; Guan, Qingfeng

    2016-03-01

    The Ag2O/Ag2CO3/multi-walled carbon nanotube (MWNTs) composite photocatalysts were prepared by calcination of the obtained precipitate. The structures and morphology of as-prepared composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS). The Ag2O/Ag2CO3/MWNTs composite photocatalysts exhibit higher degradation rate of ciprofloxacin (CIP) than the pure Ag2CO3, Ag2O/Ag2CO3 and Ag2CO3/MWNTs under visible light irradiation. The amount of loaded Ag2CO3 onto MWNTs and calcined time for Ag2CO3/MWNTs were systematically investigated, and the optimal amount of loaded Ag2CO3 and calcined time of Ag2CO3/MWNTs are 150 wt% and 10 min, respectively. The highest photocatalytic degradation rate of CIP could reach 76% under optimal conditions. The active species trapping experiments were also analyzed, the results show that the holes are main contributor for the degradation processes of CIP, furthermore the electrons, rad O2- and rad OH are also crucially influenced the photocatalytic degradation processes of CIP. The possible photocatalytic processes of CIP with Ag2O/Ag2CO3/MWNTs composite photocatalyst are also proposed.

  13. MAGNETS

    DOEpatents

    Hofacker, H.B.

    1958-09-23

    This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.

  14. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    SciTech Connect

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy; Narayanan, V. Stephen, A.

    2014-01-28

    Silver-Nickel is the well-known thermally immiscible system that makes them quite complex for the formation of alloy. This kind of alloy can be attained from electrodeposition method. In the present work, AgNi alloy was synthesized by pulsed electrodeposition in a single bath two electrode system with the use of anodic alumina membrane. The prepared AgNi alloy and pure Ag were characterized with X-ray Diffraction (XRD) for structural confirmation, Scanning Electron Microscopy (SEM) for morphological, and magnetic properties by Vibrating Sample Magnetometer, respectively. The X-ray Diffraction study shows the formation of cubic structure for pure Ag. SEM analysis reveals the double dumbbell morphology for AgNi alloy and spherically agglomeration for pure silver. Hysteresis behaviour from VSM measurement indicates that the AgNi alloy have good ferro-magnetic properties.

  15. Main Report

    PubMed Central

    2006-01-01

    scientific literature. The criteria were distributed among three main categories for each condition: The availability and characteristics of the screening test;The availability and complexity of diagnostic services; andThe availability and efficacy of treatments related to the conditions. A survey process utilizing a data collection instrument was used to gather expert opinion on the conditions in the first tier of the assessment. The data collection format and survey provided the opportunity to quantify expert opinion and to obtain the views of a diverse set of interest groups (necessary due to the subjective nature of some of the criteria). Statistical analysis of data produced a score for each condition, which determined its ranking and initial placement in one of three categories (high scoring, moderately scoring, or low scoring/absence of a newborn screening test). In the second tier of these analyses, the evidence base related to each condition was assessed in depth (e.g., via systematic reviews of reference lists including MedLine, PubMed and others; books; Internet searches; professional guidelines; clinical evidence; and cost/economic evidence and modeling). The fact sheets reflecting these analyses were evaluated by at least two acknowledged experts for each condition. These experts assessed the data and the associated references related to each criterion and provided corrections where appropriate, assigned a value to the level of evidence and the quality of the studies that established the evidence base, and determined whether there were significant variances from the survey data. Survey results were subsequently realigned with the evidence obtained from the scientific literature during the second-tier analysis for all objective criteria, based on input from at least three acknowledged experts in each condition. The information from these two tiers of assessment was then considered with regard to the overriding principles and other technology or condition

  16. Encapsulated Fe3O4 /Ag complexed cores in hollow gold nanoshells for enhanced theranostic magnetic resonance imaging and photothermal therapy.

    PubMed

    Lin, Adam Y; Young, Joseph K; Nixon, Ariel V; Drezek, Rebekah A

    2014-08-27

    Designed and fabrication of a novel magnetic hollow gold nanoshell complexes that incorporates iron oxide nanoparticles in the hollow interior. The combined effect of the smaller IONPs improved the overall magnetic properties of the design and MRI contrast capability. The overall complex could be synthesized in the range of 60-80 nm in diameter while still having a plasmonic peak in the near infrared region.

  17. 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.

  18. Dynamics of the large-scale open solar magnetic field and its specific features in the zone of the main active longitudes in 2006-2012

    NASA Astrophysics Data System (ADS)

    Ivanov, K. G.; Kharshiladze, A. F.

    2013-11-01

    The dynamics of the absolute global values (Φ) of the large-scale open solar magnetic field (LOSMF) fluxes at an interval of one solar rotation in 2006-2012 has been studied based on the Wilcox Solar Observatory data and using the ISOPAK original package for modeling the solar magnetic field. The reference points and the duration of the final quasi-biennial interval in cycle 23 (January 2006-May 2007; 17 months) and the phases of the cycle 24 minimum (May 2007-November 2009; 30 months), growth (November 2009-May 2012; 30 months), and the beginning of the maximum (May 2012-January 2013) have been determined. It has been indicated that the absolute values (Φ) decreased sharply at the beginning of the minimum, growth, and the maximum phases to ˜(2, 1.25, 0.75) × 1022 Mx, respectively. During the entire minimum phase, LOSMF corotated super-quasi-rigidly westward in the direction of solar rotation; at the beginning of the growth phase, this field started corotating mostly eastward. The LOSMF polarity reversal in the current cycle 24 started in May-June 2012 (CR 2123-2124), when fields of southern polarity rushed from the Sun's southern hemisphere toward the north. The statement that the solar cycle is a continuous series of quasi-biennial LOSMF intervals is confirmed. In particular, the minimum and growth phases are characterized by opposite LOSMF rotation directions, i.e., super-quasi-rigid corotation (twisting) and detwisting, with identical duration at least in cycle 24.

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

    PubMed Central

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

    2015-01-01

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

  20. Control of Surface Segregation in Bimetallic NiCr Nanoalloys Immersed in Ag Matrix

    PubMed Central

    Bohra, Murtaza; Singh, Vidyadhar; Grammatikopoulos, Panagiotis; Toulkeridou, Evropi; Diaz, Rosa E.; Bobo, Jean-François; Sowwan, Mukhles

    2016-01-01

    Cr-surface segregation is a main roadblock encumbering many magneto-biomedical applications of bimetallic M-Cr nanoalloys (where M = Fe, Co and Ni). To overcome this problem, we developed Ni95Cr5:Ag nanocomposite as a model system, consisting of non-interacting Ni95Cr5 nanoalloys (5 ± 1 nm) immersed in non-magnetic Ag matrix by controlled simultaneous co-sputtering of Ni95Cr5 and Ag. We employed Curie temperature (TC) as an indicator of phase purity check of these nanocomposites, which is estimated to be around the bulk Ni95Cr5 value of 320 K. This confirms prevention of Cr-segregation and also entails effective control of surface oxidation. Compared to Cr-segregated Ni95Cr5 nanoalloy films and nanoclusters, we did not observe any unwanted magnetic effects such as presence Cr-antiferromagnetic transition, large non-saturation, exchange bias behavior (if any) or uncompensated higher TC values. These nanocomposites films also lose their unique magnetic properties only at elevated temperatures beyond application requirements (≥800 K), either by showing Ni-type behavior or by a complete conversion into Ni/Cr-oxides in vacuum and air environment, respectively. PMID:26750659

  1. Solution structure of an oncogenic DNA duplex, the K-ras gene and the sequence containing a central C.A or A.G mismatch as a function of pH: nuclear magnetic resonance and molecular dynamics studies.

    PubMed

    Boulard, Y; Cognet, J A; Gabarro-Arpa, J; Le Bret, M; Carbonnaux, C; Fazakerley, G V

    1995-02-10

    The DNA duplex 5' d(GCCACCAGCTC)-d(GAGCTGGTGGC) corresponds to the sequence 29 to 39 of the K-ras gene, which contains a hot spot for mutations. This has been studied by one and two-dimensional nuclear magnetic resonance, energy minimization and molecular dynamics. The results show that it adopts a globally B-DNA type structure. We have introduced, at the central base-pair, the mismatches C.A and A.G. The mismatch position is that of the first base of the Gly12 codon, the hot spot. For the C.A mismatch we observe a structural change as a function of pH with an apparent pKa of 7.2. At low pH, the mismatch pair adopts a structure close to a classic wobble conformation with the cytidine residue displaced into the major groove. It is stabilised by two hydrogen bonds in which the adenosine residue is protonated and the cytidine residue has a significant C3'-endo population. At high pH, the mispair structure is in equilibrium between wobble and reverse wobble conformations. Similar studies are reported on the A.G mismatch, which also undergoes a transition as a function of pH. 31P spectra have been recorded on all systems and as a function of pH. No evidence for BII phosphodiester backbone conformations was found. The NMR results are well corroborated by molecular dynamics calculations performed with or without distance constraints. The dynamics at the mismatch sites have been examined. Although the overall structures are close to B-DNA, helical parameters fluctuate differently at these sites. Different hydrogen bonding alternatives in dynamic equilibrium that can involve three-centred hydrogen bonds are observed.

  2. 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.

  3. Magnetic resonance spectroscopy and molecular studies in ornithine transcarbamylase deficiency novel mutation c.802A>G in exon 8 (p.Met268Val).

    PubMed

    Jamroz, E; Paprocka, J; Sokół, M; Popowska, E; Ciara, E

    2013-01-01

    Ornithine transcarbamylase (OTC) deficiency, an X-linked, semidominant disorder, is the most common inherited de-fect in ureagenesis, resulting in hyperammonaemia type II. The OTC gene, localised on chromosome X, has been mapp-ed to band Xp21.1, proximate to the Duchenne muscular dystrophy (DMD) gene. More than 350 different mutations, including missense, nonsense, splice-site changes, small de-letions or insertions and gross deletions, have been describ-ed so far. Almost all mutations in consensus splicing sites confer a neonatal phenotype. Most mutations in the OTC gene are 'private' and are distributed throughout the gene with a paucity of mutation in the sequence encoding the leader peptide (exon 1 and beginning of exon 2) and in exon 7. They have familial origin or occur de novo. Even with sequencing of the entire reading frame and exon/intron boundaries, only about 80% of the mutations are detected in patients with proven OTC deficiency. The remainder probably occur within the introns or in regulatory domains. The authors present a 4-year-old boy with the unreported missense mutation c.802A>G. The nucleotide transition leads to amino acid substitution Met to Val at codon 268 of the OTC protein.

  4. Ag/AgBr/g-C{sub 3}N{sub 4}: A highly efficient and stable composite photocatalyst for degradation of organic contaminants under visible light

    SciTech Connect

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

    2013-10-15

    Graphical abstract: Ag/AgBr/g-C{sub 3}N{sub 4} composite photocatalysts displayed excellent photocatalytic activities on the degradation of methyl orange (MO) under visible light. The improved photocatalytic performance and stability of Ag/AgBr/g-C{sub 3}N{sub 4} originated from the synergetic effects of AgBr/g-C{sub 3}N{sub 4} interface and metallic Ag nanoparticles. ·O{sub 2}−, one of the reactive species, was responsible for the photodegradation of MO compared to H+ and ·OH. - Highlights: • Novel Ag/AgBr/g-C{sub 3}N{sub 4} composite photocatalyst was reported. • Ag/AgBr/g-C{sub 3}N{sub 4} had novel energy band combination between AgBr and g-C{sub 3}N{sub 4}. • Synergetic effects of AgBr/g-C{sub 3}N{sub 4} interface and metallic Ag nanoparticles. • Electron trapping role of metallic Ag dominated the stability of Ag/AgBr/g-C{sub 3}N{sub 4}. - Abstract: Novel Ag/AgBr/g-C{sub 3}N{sub 4} composite photocatalysts were constructed via deposition–precipitation method and extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and UV–vis diffuse reflectance spectroscopy (DRS). Under visible light (λ > 420 nm), Ag/AgBr/g-C{sub 3}N{sub 4} composite photocatalysts displayed much higher photocatalytic activities than those of Ag/AgBr and g-C{sub 3}N{sub 4} for degradation of methyl orange (MO). 50% Ag/AgBr/g-C{sub 3}N{sub 4} presented the best photocatalytic performance, which was mainly attributed to the synergistic effects of AgBr/g-C{sub 3}N{sub 4} interface and the in situ metallic Ag nanoparticles for efficiently separating electron–hole pairs. Furthermore, Ag/AgBr/g-C{sub 3}N{sub 4} remained good photocatalytic activity through 5 times of cycle experiments. Additionally, the radical scavengers experiment indicated that ·O{sub 2}{sup −} was the main reactive species for the MO degradation under visible light.

  5. Antibacterial biodegradable Mg-Ag alloys.

    PubMed

    Tie, D; Feyerabend, F; Müller, W D; Schade, R; Liefeith, K; Kainer, K U; Willumeit, R

    2013-06-16

    The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4) and aging (T6) heat treatment. The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH)₂ and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7), revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231) and Staphylococcus epidermidis (DSMZ 3269), and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

  6. 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.

  7. Progress with the AGS Booster

    SciTech Connect

    Weng, W.T.

    1988-01-01

    Rare K-decay, neutrino and heavy ion physics demands that a rapid- cycling high vacuum and high intensity Booster be built for the AGS at Brookhaven. For each mode of operation there are corresponding accelerator physics and design issues needing special attention. Problems pertinent to any single mode of operation have been encountered and solved before, but putting high intensity proton requirements and high vacuum heavy ion requirements into one machine demands careful design considerations and decisions. The lattice design and magnet characteristics will be briefly reviewed. Major design issues will be discussed and design choices explained. Finally, the construction status and schedule will be presented. 6 refs., 6 figs.

  8. Characterization of the antiferromagnetism in Ag(pyz)2(S2O8) with a two-dimensional square lattice of Ag 2+ ions (Ag=silver, Pyz-pyrdzine, S2O8=sulfate)

    SciTech Connect

    Singleton, John; Mc Donald, R; Sengupta, P; Cox, S; Manson, J; Southerland, H; Warter, M; Stone, K; Stephens, P; Lancaster, T; Steele, A; Blundell, S; Baker, P; Pratt, F; Lee, C; Whangbo, M

    2009-01-01

    X-ray powder diffraction and magnetic susceptibility measurements show that Ag(pyz){sub 2}(S{sub 2}O{sub 8}) consists of 2D square nets of Ag{sup 2+} ions resulting from the corner-sharing of axially elongated AgN{sub 4}O{sub 2} octahedra and exhibits characteristic 2D antiferromagnetism. Nevertheless, {mu}{sup +}Sr measurements indicate that Ag(pyz){sub 2}(S{sub 2}O{sub 8}) undergoes 3D magnetic ordering below 7.8(3) K.

  9. Ag-Mn nanoparticles: Three-dimensional finite size effect of the spin glass state

    NASA Astrophysics Data System (ADS)

    Ederth, J.; Hoel, A.; Johansson, C. I.; Kiss, L. B.; Olsson, E.; Granqvist, C. G.; Nordblad, P.

    1999-12-01

    Ag-Mn nanoparticles were prepared by advanced gas evaporation. Their composition corresponded to Ag0.89Mn0.11, and the particle size distribution was log normal. The particles demonstrated an unambiguous spin glass behavior with the temperature dependent magnetic susceptibility displaying a plateau at ˜25 K. The magnetic domains were limited by the size of the particles.

  10. Preparation, characterization and photocatalytic activity of visible-light-driven plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites

    SciTech Connect

    Li, Xiaojuan Tang, Duanlian; Tang, Fan; Zhu, Yunyan; He, Changfa; Liu, Minghua Lin, Chunxiang; Liu, Yifan

    2014-08-15

    Highlights: • A plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} photocatalyst has been successfully synthesized. • Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites exhibit high visible light photocatalytic activity. • Ag/AgBr/ZnFe{sub 2}O{sub 4} photocatalyst is stable and magnetically separable. - Abstract: A visible-light-driven plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposite has been successfully synthesized via a deposition–precipitation and photoreduction through a novel one-pot process. X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy were employed to investigate the crystal structure, chemical composition, morphology, and optical properties of the as-prepared nanocomposites. The photocatalytic activities of the nanocomposites were evaluated by photodegradation of Rhodamine B (RhB) and phenol under visible light. The results demonstrated that the obtained Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites exhibited higher photocatalytic activity as compared to pure ZnFe{sub 2}O{sub 4}. In addition, the sample photoreduced for 20 min and calcined at 500 °C achieved the highest photocatalytic activity. Furthermore, the Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposite has high stability under visible light irradiation and could be conveniently separated by using an external magnetic field.

  11. Surface spin polarization induced ferromagnetic Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Shih, Po-Hsun; Li, Wen-Hsien; Wu, Sheng Yun

    2016-05-01

    We report on the observation of ferromagnetic spin polarized moments in 4.5 nm Ag nanoparticles. Both ferromagnetic and diamagnetic responses to an applied magnetic field were detected. The spin polarized moments shown under non-linear thermoinduced magnetization appeared on the surface atoms, rather than on all the atoms in particles. The saturation magnetization departed substantially from the Bloch T3/2-law, showing the existence of magnetic anisotropy. The Heisenberg ferromagnetic spin wave model for Ha-aligned moments was then employed to identify the magnetic anisotropic energy gap of ~0.12 meV. Our results may be understood by assuming the surface magnetism model, in which the surface atoms give rise to polarized moments while the core atoms produce diamagnetic responses.

  12. Fabrication of graphene oxide enwrapped Z-scheme Ag2SO3/AgBr nanoparticles with enhanced visible-light photocatalysis

    NASA Astrophysics Data System (ADS)

    Wan, Yujuan; Liang, Chunyan; Xia, Yue; Huang, Wei; Li, Zelin

    2017-02-01

    A novel graphene oxide (GO) enwrapped Ag2SO3/AgBr (GO/Ag2SO3/AgBr) composite was fabricated through a facile solution approach via electrostatic interaction and precipitation transformation reaction for the first time. The results of XRD, Raman, SEM, TEM and XPS confirmed the structure, morphology and composition of the GO/Ag2SO3/AgBr composite very well. The Ag2SO3/AgBr nanoparticles were found to be encapsulated by GO sheets. The photocatalytic activity of the composite was investigated by the degradation of methyl orange (MO), rhodamine B (RhB) and methylene blue (MB) in water under visible light. The incorporation of GO sheets not only significantly enhanced the photocatalytic activity but also improved the reusability of Ag2SO3/AgBr nanoparticles. The photocatalytic ability of GO/Ag2SO3/AgBr can be maintained at a high level for 4 times cycle experiments. The trapping experiments confirmed that holes and superoxide ion radicals were the main active species responsible for the degradation reaction. A plasmonic Z-scheme photocatalytic mechanism was proposed to illustrate the possible transferred and separated behavior of electron-hole pairs among Ag, Ag2SO3, AgBr and GO quaternary system under visible light irradiation.

  13. Investigation of Ag-sheathed multi-filamentary Bi2Sr 2CaCu2O8-x superconducting round wires processed with overpressure, for high field magnets

    NASA Astrophysics Data System (ADS)

    Matras, Maxime

    The need for electromagnets that generate fields >20 T has grown in numerous applications,, especially in high energy physics and NMR research. Conventional resistive magnets require a tremendous amount of power to generate these fields. In contrast superconducting magnets require significantly smaller amounts of power. The low temperature superconductors are limited to fields below 25 T, whereas high temperature superconductors (HTS) show large critical current density above 25 T. Ag-sheathed Bi2Sr2CaCu2O x (2212) multifilamentary round wire is the only HTS that can be made as a round wire with isotropic electrical behavior in magnetic field, and it has a high irreversibility field at 4.2 K. These properties make 2212 an ideal candidate for high-field magnets. Only recently has the critical current density (Jc) in 2212 been increased to a value that makes it a viable magnet material. In the past, the gas-filled porosity in the as-drawn 2212 filaments agglomerated into filament-size bubbles during the heat treatment of the wire at 1 atm. These bubbles severely limited the supercurrent flow in the wire and the gases in the bubbles could also expand at high temperature generating 2212 leakage. The bubbles and leakage were eliminated using overpressure (OP) processing, which was recently developed for 2212 at the Applied Superconductivity Center. OP processing uses a gas that isostatically compresses the Ag wire during the entire heat treatment of the wire, which eliminates the bubbles and prevents leakage. My studies showed that using OP at 100 atm increases Jc by 800 % compared to the conventional processing at 1 atm. This makes 2212 round wire a very competitive candidate for high-field magnets. The wire compression with OP is the key to reach high J c and it was studied as a function of time and temperature to optimize the densification process. We found that the wire diameter decreases by 3.8 +/- 0.3% after the full OP heat treatment (OP-HT) at 50 atm and by 3

  14. First results of proton injection commissioning of the AGS Booster synchrotron

    SciTech Connect

    Reece, R.K.; Ahrens, L.; Alessi, J.; Bleser, E.; Brennan, J.M.; Luccio, A.; Skelly, J.; Soukas, A.; van Asselt, W.; Weng, W.T.; Witkover, R.

    1991-01-01

    Beam performance for the injection phase of proton beam commissioning of the AGS Booster synchrotron will be presented. The beam from the 200 MeV Linac is transported through a new beam line into the Booster. This Linac-to Booster (LTB) beam line includes a 126{degree} bend and brings the injected beam onto the Booster injection orbit through the backleg of a main ring dipole magnet. Transfer of beam from the Linac to the Booster, spiralling beam and closing the orbit in the Booster ring are discussed. Injection and transport through one sector of the ring has been accomplished. 8 refs., 1 fig.

  15. Microstructure, mechanical properties, bio-corrosion properties and antibacterial properties of Ti-Ag sintered alloys.

    PubMed

    Chen, Mian; Zhang, Erlin; Zhang, Lan

    2016-05-01

    In this research, Ag element was selected as an antibacterial agent to develop an antibacterial Ti-Ag alloy by a powder metallurgy. The microstructure, phase constitution, mechanical properties, corrosion resistance and antibacterial properties of the Ti-Ag sintered alloys have been systematically studied by X-ray diffraction (XRD), scanning electron microscope (SEM), compressive test, electrochemical measurements and antibacterial test. The effects of the Ag powder size and the Ag content on the antibacterial property and mechanical property as well as the anticorrosion property have been investigated. The microstructure results have shown that Ti-Ag phase, residual pure Ag and Ti were the mainly phases in Ti-Ag(S75) sintered alloy while Ti2Ag was synthesized in Ti-Ag(S10) sintered alloy. The mechanical test indicated that Ti-Ag sintered alloy showed a much higher hardness and the compressive yield strength than cp-Ti but the mechanical properties were slightly reduced with the increase of Ag content. Electrochemical results showed that Ag powder size had a significant effect on the corrosion resistance of Ti-Ag sintered alloy. Ag content increased the corrosion resistance in a dose dependent way under a homogeneous microstructure. Antibacterial tests have demonstrated that antibacterial Ti-Ag alloy was successfully prepared. It was also shown that the Ag powder particle size and the Ag content influenced the antibacterial activity seriously. The reduction in the Ag powder size was benefit to the improvement in the antibacterial property and the Ag content has to be at least 3wt.% in order to obtain a strong and stable antibacterial activity against Staphylococcus aureus bacteria. The bacterial mechanism was thought to be related to the Ti2Ag and its distribution.

  16. Synthesis and photocatalytic performance of an efficient Ag@AgBr/K{sub 2}Ti{sub 4}O{sub 9} composite photocatalyst under visible light

    SciTech Connect

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

    2014-08-15

    Highlights: • The plasmatic Ag@AgBr sensitized K{sub 2}Ti{sub 4}O{sub 9} composite photocatalysts. • Ag@AgBr greatly increased visible light absorption for K{sub 2}Ti{sub 4}O{sub 9}. • The plamonic photocatalysts exhibited enhanced activity for the degradation of RhB. - Abstract: Ag@AgBr nanoparticle-sensitized K{sub 2}Ti{sub 4}O{sub 9} composite photocatalysts (Ag@AgBr/K{sub 2}Ti{sub 4}O{sub 9}) were prepared by a facile precipitation–photoreduction method. The photocatalytic activities of the Ag@AgBr/K{sub 2}Ti{sub 4}O{sub 9} nanocomposites were evaluated for photocatalytic degradation of (RhB) under visible light irradiation. The composites exhibited excellent visible light absorption, which was attributable to the surface plasmon effect of Ag nanoparticles. The Ag@AgBr was uniformly scattered on the surface of K{sub 2}Ti{sub 4}O{sub 9} and possessed sizes in the range of 20–50 nm. The loading amount of Ag@AgBr was also studied, and was found to influence the absorption spectra of the resulting composites. Approximately 95.9% of RhB was degraded by Ag@AgBr (20 wt.%)/K{sub 2}Ti{sub 4}O{sub 9} after irradiation for 1 h. The stability of the material was also investigated by performing consecutive runs. Additionally, studies performed using radical scavengers indicated that ·O{sub 2}{sup −} and Br{sup 0} acted as the main reactive species. Based on the experimental results, a photocatalytic mechanism for organics degradation over Ag@AgBr/K{sub 2}Ti{sub 4}O{sub 9} photocatalysts was proposed.

  17. Ag surface diffusion and out-of-bulk segregation in CrN-Ag nano-composite coatings.

    PubMed

    Incerti, L; Rota, A; Ballestrazzi, A; Gualtieri, E; Valeri, S

    2011-10-01

    CrN-Ag nanocomposite coatings are deposited on Si(100) wafers and 20MnCr5 steel disks in a mixed Ar+N2 atmosphere by reactive magnetron sputtering. Structure, composition and morphology were investigated by Scanning Electron Microscopy (SEM), Auger Electron Spectroscopy (AES), X-ray Photoemission Spectroscopy (XPS), X-ray Diffraction (XRD) and Focused Ion Beam (FIB) cross sectional analysis. The as deposited film matrix is mainly composed by CrN phase (78%), but a relevant part (28%) is composed by Cr2N. Ag agglomerates in the CrN matrix forming elongated grains 200-400 nm wide and 50-100 nm high, which extends on the top of CrN columns. At the surface Ag aggregates into two different structures: large tetrahedral crystalline clusters, with typical dimension ranging from 200 to 500 nm, and smaller Ag nanoparticles with diameter of 15-25 nm. The annealing in N2 atmosphere up to 500 degrees C does not affect size and distribution of the Ag grains in the sub-surface region, while it induces a size increase of the bigger Ag clusters on the surface, mainly related to Ag surface diffusion and clusters coalescence. Annealing at higher temperature leads to an evident Ag out-of-bulk segregation, generating Ag depleted voids in the near-surface region, and further increasing of the Ag clusters size at the surface. Tribological tests on as deposited CrN-Ag film reveal a coefficient of friction against a steel ball reduced with respect to CrN film, probably related to the presence of Ag which acts as solid lubricant, but the coating is removed after a very short sliding distance. The poor mechanical properties of the realized Ag-based coatings are confirmed by lower hardness and Young modulus values with respect to pure CrN.

  18. Synthesis of AG@AgCl Core-Shell Structure Nanowires and Its Photocatalytic Oxidation of Arsenic (III) Under Visible Light.

    PubMed

    Qin, Yanyan; Cui, Yanping; Tian, Zhen; Wu, Yangling; Li, Yilian

    2017-12-01

    Ag@AgCl core-shell nanowires were synthesized by oxidation of Ag nanowires with moderate FeCl3, which exhibited excellent photocatalytic activity for As(III) oxidation under visible light. It was proved that the photocatalytic oxidation efficiency was significantly dependent on the mole ratio of Ag:AgCl. The oxidation rate of As(III) over Ag@AgCl core-shell nanowires first increased with the decrease of Ag(0) percentage, up until the optimized synthesis mole ratio of Ag nanowires:FeCl3 was 2.32:2.20, with 0.023 mg L(-1) min(-1) As(III) oxidation rate; subsequently, the oxidation rate dropped with the further decrease of Ag(0) percentage. Effects of the pH, ionic strength, and concentration of humic acid on Ag@AgCl photocatalytic ability were also studied. Trapping experiments using radical scavengers confirmed that h(+) and ·O2(-) acted as the main active species during the visible-light-driven photocatalytic process for As(III) oxidation. The recycling experiments validated that Ag@AgCl core-shell nanowires were a kind of efficient and stable photocatalyst for As(III) oxidation under visible-light irradiation.

  19. 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.

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  2. 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.

  3. 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.

  4. Synthesis and Functions of Ag2S Nanostructures

    NASA Astrophysics Data System (ADS)

    Cui, Chunyan; Li, Xiaoru; Liu, Jixian; Hou, Yongchao; Zhao, Yuqing; Zhong, Guocheng

    2015-11-01

    The paper presents a review about synthesis and applications of Ag2S nanostructures. As the modern photoelectric and biological materials, Ag2S nanomaterials are potentially useful for both structure and function purposes. Ag2S is a direction narrow band gap semiconductor with special properties. Ag2S nanostructures have been widely researched in chemistry and biochemistry fields because of their unusual optical, electrical, and mechanical properties. It can also be used in many fields, such as photovoltaic cells and infrared detector. In the past few years, Ag2S nanostructures have been synthesized by various methods. The article mainly discusses the four types of preparation methods. Moreover, this article shows a detailed review on the new properties, fabrication, and applications of Ag2S nanocrystals.

  5. Effect of Ag addition to L1{sub 0} FePt and L1{sub 0} FePd films grown by molecular beam epitaxy

    SciTech Connect

    Tokuoka, Y.; Seto, Y.; Kato, T.; Iwata, S.

    2014-05-07

    L1{sub 0} ordered FePt-Ag (5 nm) and FePd-Ag (5 nm) films were grown on MgO (001) substrate at temperatures of 250–400 °C by using molecular beam epitaxy method, and their crystal and surface structures, perpendicular magnetic anisotropies and Curie temperatures were investigated. In the case of FePt-Ag, Ag addition with the amount of 10–20 at. % was effective to promote L1{sub 0} ordering and granular growth, resulting in the increase of the perpendicular magnetic anisotropy and coercivity of the FePt-Ag films. On the other hand, in the case of FePd-Ag, Ag addition changed the surface morphology from island to continuous film associated with the reductions of its coercivity and perpendicular anisotropy. The variations of lattice constants and Curie temperature with Ag addition were significantly different between FePt-Ag and FePd-Ag. For FePd-Ag, the c and a axes lattice spacings and Curie temperature gradually changed with increasing Ag content, while they unchanged for FePt-Ag. These results suggest the possibility of the formation of FePdAg alloy in FePd-Ag, while Ag segregation in FePt-Ag.

  6. Ferromagnetic resonance of ultrathin Co /Ag superlattices on Si(111)

    NASA Astrophysics Data System (ADS)

    Kakazei, G. N.; Martin, P. P.; Ruiz, A.; Varela, M.; Alonso, M.; Paz, E.; Palomares, F. J.; Cebollada, F.; Rubinger, R. M.; Carmo, M. C.; Sobolev, N. A.

    2008-04-01

    Ferromagnetic resonance (FMR) is used to probe the magnetic properties of Co /Ag superlattices (SLs) with ultrathin Co layers (2-6Å). Different series of 5×[Ag/Co] multilayers have been grown by molecular beam epitaxy on Si(111) substrates, monitoring the growth by reflection high energy electron diffraction. Cross-section transmission electron microscopy confirms the growth of local areas with the designed SL periodicity, a sharp compositional modulation, well defined Ag-Co interfaces, and a perfect fcc (111) stacking. FMR spectra have been recorded at various polar angles in the 0°-90° range. A single and extremely broad resonance peak is observed in all cases. While SLs with Ag layers thinner than 10Å exhibit similar values of the perpendicular anisotropy, a clear reduction is observed for samples with Ag layers about 14Å thick. Possible causes for this change are discussed.

  7. @AuAg nanostructures

    NASA Astrophysics Data System (ADS)

    Singh, Rina; Soni, R. K.

    2014-09-01

    Bimetallic and trimetallic nanoparticles have attracted significant attention in recent times due to their enhanced electrochemical and catalytic properties compared to monometallic nanoparticles. The numerical calculations using Mie theory has been carried out for three-layered metal nanoshell dielectric-metal-metal (DMM) system consisting of a particle with a dielectric core (Al@Al2O3), a middle metal Ag (Au) layer and an outer metal Au (Ag) shell. The results have been interpreted using plasmon hybridization theory. We have also prepared Al@Al2O3@Ag@Au and Al@Al2O3@AgAu triple-layered core-shell or alloy nanostructure by two-step laser ablation method and compared with calculated results. The synthesis involves temporal separations of Al, Ag, and Au deposition for step-by-step formation of triple-layered core-shell structure. To form Al@Ag nanoparticles, we ablated silver for 40 min in aluminium nanoparticle colloidal solution. As aluminium oxidizes easily in water to form alumina, the resulting structure is core-shell Al@Al2O3. The Al@Al2O3 particle acts as a seed for the incoming energetic silver particles for multilayered Al@Al2O3@Ag nanoparticles is formed. The silver target was then replaced by gold target and ablation was carried out for different ablation time using different laser energy for generation of Al@Al2O3@Ag@Au core-shell or Al@Al2O3@AgAu alloy. The formation of core-shell and alloy nanostructure was confirmed by UV-visible spectroscopy. The absorption spectra show shift in plasmon resonance peak of silver to gold in the range 400-520 nm with increasing ablation time suggesting formation of Ag-Au alloy in the presence of alumina particles in the solution.

  8. Aniline chlorination by in situ formed Ag-Cl complexes under simulated solar light irradiation.

    PubMed

    Hu, Xuefeng; Wang, Xiaowen; Dong, Liuliu; Chang, Fei; Luo, Yongming

    2015-01-01

    Ag speciation in a chloride medium was dependent upon the Cl/Ag ratio after releasing into surface water. In this study, the photoreaction of in situ formed Ag-Cl species and their effects on aniline photochlorination were systematically investigated. Our results suggested that formation of chloroaniline was strongly relevant to the Cl/Ag ratio and could be interpreted using the thermodynamically expected speciation of Ag in the presence of Cl-. AgCl was the main species responsible for the photochlorination of aniline. Both photoinduced hole and •OH drove the oxidation of Cl- to radical •Cl, which promoted the chlorination of aniline. Ag0 formation was observed from the surface plasmon resonance absorption during AgCl photoreaction. This study revealed that Ag+ released into Cl--containing water may result in the formation of chlorinated intermediates of organic compounds under solar light irradiation.

  9. Solution structure of peptide AG4 used to form silver nanoparticles

    SciTech Connect

    Lee, Eunjung; Kim, Dae-Hee; Woo, Yoonkyung; Hur, Ho-Gil; Lim, Yoongho

    2008-11-21

    The preparation of silver nanoparticles (AgNPs) is of great interest due to their various biological activities, such as observed in their antimicrobial and wound healing actions. Moreover, the formation of AgNPs using silver-binding peptide has certain advantages because they can be made in aqueous solution at ambient temperature. The solution structure of the silver-binding peptide AG4 was determined using nuclear magnetic resonance spectroscopy, and the site of the AG4 interaction with AgNPs was elucidated.

  10. Ag(nic)2 (nic = nicotinate): a spin-canted quasi-2D antiferromagnet composed of square-planar S = 1/2 Ag(II) ions.

    PubMed

    Manson, Jamie L; Woods, Toby J; Lapidus, Saul H; Stephens, Peter W; Southerland, Heather I; Zapf, Vivien S; Singleton, John; Goddard, Paul A; Lancaster, Tom; Steele, Andrew J; Blundell, Stephen J

    2012-02-20

    Square-planar S = 1/2 Ag(II) ions in polymeric Ag(nic)(2) are linked by bridging nic monoanions to yield 2D corrugated sheets. Long-range magnetic order occurs below T(N) = 11.8(2) K due to interlayer couplings that are estimated to be about 30 times weaker than the intralayer exchange interaction.

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

    PubMed Central

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

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

    PubMed

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

    2016-09-12

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

  14. AgSTAR Partners

    EPA Pesticide Factsheets

    AgSTAR’s Partner Program builds stronger relationships with state and non-governmental stakeholders to support all phases of anaerobic digester projects: planning, deployment, and long-term success.

  15. Tuning the transmittance of colloidal solution by changing the orientation of Ag nanoplates in ferrofluid.

    PubMed

    Mao, Yiwu; Liu, Jing; Ge, Jianping

    2012-09-11

    Ag nanoplates and Fe(3)O(4) nanoparticle-based ferrofluids were utilized to fabricate a magnetic field controlled optic switch. The changing of light transmittance (LT) is caused by the rotation of Ag nanoplates, whose long axis always follows the orientation of external magnetic field to minimize the potential energy. The sensitivity of switching was optimized by choosing Ag nanoplates with appropriate size and concentration. The switching of transmission is proved to be fast and fully reversible. This phenomenon not only indicates an effective method to adjust the propagation of optical signals, but also reveals the possibility and great potential to develop magnetic controlled functional devices.

  16. Ag-Al-Ca

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Ag-Al-Ca' with the content:

  17. Synthesis and characterization of Ag-containing calcium phosphates with various Ca/P ratios.

    PubMed

    Gokcekaya, Ozkan; Ueda, Kyosuke; Narushima, Takayuki; Ergun, Celaletdin

    2015-08-01

    Ag-containing calcium phosphate (CaP) powders were synthesized by a precipitation method using aqueous solutions of calcium nitrate, silver nitrate, and ammonium phosphate. The powders were sintered at temperatures ranging from 1173 to 1473 K. The charged atomic ratios of (Ca+Ag)/P and Ag/(Ca+Ag) in solution were varied from 1.33 to 1.67 and from 0 to 0.30, respectively. The Ag content in the as-precipitated CaP powders increased with the charged Ag/(Ca+Ag) atomic ratio in solution and was lower than the charged Ag/(Ca+Ag) value. The as-precipitated CaP powders consisted of hydroxyapatite (HA) as the main phase. Ag nanoparticles were observed on the as-precipitated HA particles under all conditions of Ag addition. After the sintering, HA, β-TCP (tricalcium phosphate), α-TCP, and β-CPP (calcium pyrophosphate) were mainly detected as CaPs on the basis of the Ca/P atomic ratio of the as-precipitated powders. The addition of Ag stabilized the β-TCP phase, and the distribution of Ag in β-TCP was homogeneous. A metallic Ag phase coexisted with HA. The solubility of Ag in HA was estimated to be 0.0019-0.0061 (Ag/(Ca+Ag)) atomic ratio, which was lower than that in β-TCP (higher than 0.0536) and higher than that of β-CPP (below the detection limit of analyses).

  18. 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.

  19. Plasmon-assisted degradation of methylene blue with Ag/AgCl/montmorillonite nanocomposite under visible light.

    PubMed

    Sohrabnezhad, Sh; Zanjanchi, M A; Razavi, M

    2014-09-15

    Metal-semiconductor compounds, such as Ag/AgX (X=Cl, Br, I), enable visible light absorption and separation of photogenerated electron-hole through surface plasmon resonance (SPR) effect. However, the electron-hole generated and separated by light are vulnerable in Ag/AgX phase because of the occurrence of secondary recombined. In order to more effectively utilize the SPR photocatalytic effect, nanoparticles are located in a matrix. In this article, Ag/AgCl nanoparticles were synthesized in montmorillonite (MMT) matrix using dispersion method and light irradiation. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed intercalation of Ag/AgCl nanoparticles into the clay layers. The as-prepared plasmonic photocatalyst exhibited an enhanced and stable photoactivity for the degradation of methylene blue (MB) under visible light. The high activity was attributed to the surface plasmon resonance (SPR) exhibited by Ag nanoparticles on the surface of AgCl. The detection of reactive species by radical scavengers displays that O2- and OH- are the main reactive species for the degradation of MB under visible light irradiation. The studies showed that 20 min illumination under visible light can complete degradation of methylene blue (MB), and indicate a high stability of photocatalytic degradation. The mechanism of separation of the photo-generated electrons and holes at the Ag/AgCl-MMT nanocomposite was discussed.

  20. Spin glass in semiconducting KFe1.05Ag0.88Te2 single crystals

    DOE PAGES

    Ryu, H.; Lei, H.; Klobes, B.; ...

    2015-05-26

    We report discovery of KFe1.05Ag0.88Te2 single crystals with semiconducting spin glass ground state. Composition and structure analysis suggest nearly stoichiometric I4/mmm space group but allow for the existence of vacancies, absent in long range semiconducting antiferromagnet KFe1.05Ag0.88Te2. The subtle change in stoichometry in Fe/Ag sublattice changes magnetic ground state but not conductivity, giving further insight into the semiconducting gap mechanism.

  1. Effect of thermal annealing on the microstructures and photocatalytic performance of silver orthophosphate: The synergistic mechanism of Ag vacancies and metallic Ag

    NASA Astrophysics Data System (ADS)

    Yan, Tingjiang; Guan, Wenfei; Xiao, Ying; Tian, Jun; Qiao, Zheng; Zhai, Huishan; Li, Wenjuan; You, Jinmao

    2017-01-01

    In this work, a simple thermal annealing route has been developed to improve the photocatalytic performance of silver orthophosphate (Ag3PO4) photocatalyst toward organic pollutants degradation under visible light irradiation. The experimental results indicated that thermal treatment of Ag3PO4 led to an obvious lattice shift towards right and significantly narrowed band gap energies due to the formation of Ag vacancies and metallic Ag during Ag3PO4 decomposition. These structural variations notably affected the photocatalytic performance of Ag3PO4 photocatalysts. The activity of the annealed samples was found to be significantly enhanced toward the degradation of MO dye. The highest activity was observed over the sample annealed at 400 °C, which exceeded that of pristine Ag3PO4 by a factor of about 21 times. By means of photoluminescence spectroscopy and photoelectrochemical measurements, we propose that the enormous enhancement in activity was mainly attributed to the efficient separation of photogenerated electrons and holes driven by the synergistic effect of Ag vacancies and metallic Ag. The strong interaction between annealed particles also inhibited the dissolution of Ag+ from Ag3PO4 into aqueous solution, contributing to an improved photocatalytic stability. The strategy presented here provides an ideal platform for the design of other highly efficient and stable Ag-based photocatalysts for broad applications in the field of photocatalysis.

  2. Plasmon-induced photodegradation of toxic pollutants with Ag-AgI/Al2O3 under visible-light irradiation.

    PubMed

    Hu, Chun; Peng, Tianwei; Hu, Xuexiang; Nie, Yulun; Zhou, Xuefeng; Qu, Jiuhui; He, Hong

    2010-01-20

    A plasmonic photocatalyst Ag-AgI supported on mesoporous alumina (Ag-AgI/Al(2)O(3)) was prepared by deposition-precipitation and photoreduction methods. The catalyst showed high and stable photocatalytic activity for the degradation and mineralization of toxic persistent organic pollutants, as demonstrated with 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and trichlorophenol (TCP) under visible light or simulated solar light irradiation. On the basis of electron spin resonance, cyclic voltammetry analyses under a variety of experimental conditions, two electron transfer processes were verified from the excited Ag NPs to AgI and from 2-CP to the Ag NPs, and the main active species of O(2)(*-) and excited h(+) on Ag NPs were involved in the photoreaction system of Ag-AgI/Al(2)O(3). A plasmon-induced photocatalytic mechanism was proposed. Accordingly, the plasmon-induced electron transfer processes elucidated the photostability of Ag-AgI/Al(2)O(3). This finding indicates that the high photosensitivity of noble metal NPs due to surface plasmon resonance could be applied toward the development of new plasmonic visible-light-sensitive photocatalysts and photovoltaic fuel cells.

  3. In vitro corrosion of dental Ag-based alloys in polyvinylpyrrolidone iodine solution.

    PubMed

    Ochi, Morio; Endo, Kazuhiko; Ohno, Hiroki; Takasusuki, Norio; Matsubara, Hideki; Maida, Takeo

    2005-09-01

    The corrosion and tarnish behaviors of three Ag-based alloys (Ag-Pd-Cu-Au alloy, Ag-In alloy, and Ag-Sn-Zn alloy) in polyvinylpyrrolidone iodine (povidone-iodine) solution were examined. The degree of tarnish was evaluated by visible-ray spectrocolorimetry. Corrosion potential measurements and analyses of corrosion products by X-ray diffractometry were carried out to elucidate the corrosion mechanism. The corrosion rate of the three Ag-based alloys in povidone-iodine solution at its practical concentration used as a gargle solution was so fast that the alloys tarnished within 10 seconds of immersion with the formation of AgI. Thermodynamic consideration and the results of surface analysis by X-ray diffractometry revealed that the main anodic and cathodic reactions were Ag + I(-)-->AgI + e- and I2 + 2e(-)-->2I- respectively.

  4. ZnWO4 nanorods decorated with Ag/AgBr nanoparticles as highly efficient visible-light-responsive photocatalyst for dye AR18 photodegradation

    NASA Astrophysics Data System (ADS)

    Li, Kebin; Xue, Jie; Zhang, Yanhui; Wei, Hong; Liu, Yalan; Dong, Chengxing

    2014-11-01

    A novel Ag-AgBr/ZnWO4 nanorod heterostructure composite was prepared via a facile deposition-precipitation method with ZnWO4 nanorods as the substrate, and characterized by XRD, SEM-EDX, TEM, XPS, and DRS to confirm its structure, morphology, composition, and optical property. The composite was used as a photocatalyst to destroy azo dye Acid Red 18 (AR18) under visible light irradiation. The effects of catalyst composition, solution pH, catalyst loading, and initial dye concentration on photocatalytic degradation rate and efficiency were examined. It was revealed that the photocatalytic activity of Ag-AgBr/ZnWO4 nanojunction system was higher than that of the single ZnWO4 or Ag-AgBr for AR18 degradation under visible light irradiation. The optimal content of Ag-AgBr in Ag-AgBr/ZnWO4 composite was 0.58:1 of Ag/W molar ratio using in the catalyst preparation. Acid pH and decreasing dye initial concentration were favorable to AR18 photodegradation, but the catalyst loading had an optimal value. The catalyst was stable and recyclable, after five successive cycles the photoactivity was fully maintained and the XRD patterns of AgBr displayed no evident change. Photoluminescence spectra revealed the enhanced photocatalytic activity and stability were closely related to the efficient separation of photogenerated carriers in Ag-AgBr/ZnWO4 nanojunction system. Superoxide radicals and holes were found to be main active species for AR18 photodegradation. Finally, the possible mechanism for AR18 degradation over Ag-AgBr/ZnWO4 nanorods under visible light irradiation was proposed as well.

  5. Plasmon resonances of Ag(001) and Ag(111) studied by power density absorption and photoyield

    NASA Astrophysics Data System (ADS)

    Raseev, Georges

    2013-09-01

    This paper models the surface and bulk plasmon resonances in photoabsorption and photoelectron spectra (PES) of the Ag(001) and the Ag(111) surfaces in the region of 2.8-10 eV excited with a p or transverse magnetic linearly polarized laser incident at 45°. Using the recently developed vector potential from electron density-coupled integro-differential equations (VPED-CIDE, [1,2]) model, we calculate the electron escaping probability from the power density absorption, Feibelman's parameter d⊥, the reflectance and the Fermi PE cross section. In the PES experiment the work function is lowered from 4.5 to 2.8 eV by adsorption of sodium. In our model, this lowering is introduced by adding a phenomenological term to the DFT-LDA model potential of Chulkov et al. [3]. For both Ag(001) and Ag(111), the calculated observables display two plasmon resonances, the multipole surface at 3.70 eV and the bulk at 3.90 eV, in fair agreement with the experimental PES of Barman et al. [4,5] and the reflectance. Except for the Fermi PE cross section of Ag(001) which does not display the multipole surface plasmon resonance at 3.70 eV. This poor result is probably due to a poor calculation of the conduction band wave functions obtained from the Schrödinger equation using the modified DFT-LDA model potential of Chulkov et al.

  6. Heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst with enhanced photocatalytic activity and stability under visible light

    NASA Astrophysics Data System (ADS)

    Wang, Wan-Sheng; Du, Hong; Wang, Rui-Xia; Wen, Tao; Xu, An-Wu

    2013-03-01

    A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high efficiencies of the photocatalytic activity and the improved stability. With the assistance of Ag3PO4/AgBr/Ag heterostructures, only 8 min and 12 min are taken to completely decompose MO and MB molecules under visible-light irradiation, respectively. Furthermore, the photodegradation rate does not show an obvious decrease during ten successive cycles, indicating that our heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts are extremely stable under visible-light irradiation.A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high

  7. Localised Ag(+) vibrations at the origin of ultralow thermal conductivity in layered thermoelectric AgCrSe2.

    PubMed

    Damay, F; Petit, S; Rols, S; Braendlein, M; Daou, R; Elkaïm, E; Fauth, F; Gascoin, F; Martin, C; Maignan, A

    2016-03-22

    In materials science, the substructure approach consists in imagining complex materials in which a particular property is associated with a distinct structural feature, so as to combine different chosen physical characteristics, which otherwise have little chance to coexist. Applied to thermoelectric materials, it has been used to achieve simultaneously phonon-glass and electron-crystal properties. Mostly studied for its superionic conductivity, AgCrSe2 is a naturally layered compound, which achieves very low thermal conductivity, ~0.4 W.K(-1).m(-1) at RT (room temperature), and is considered a promising thermoelectric. The Cr atoms of the [CrSe2]∞ layer bear a spin S = 3/2, which orders below TN = 55 K. Here we report low temperature inelastic neutron scattering experiments on AgCrSe2, alongside the magnetic field evolution of its thermal and electrical transport. We observe a very low frequency mode at 3 meV, ascribed to large anharmonic displacements of the Ag(+) ions in the [Ag]∞ layer, and 2D magnetic fluctuations up to 3 TN in the chromium layer. The low thermal conductivity of AgCrSe2 is attributed to acoustic phonon scattering by a regular lattice of Ag(+) oscillating in quasi-2D potential wells. These findings highlight a new way to achieve localised phonon modes in a perfectly crystalline solid.

  8. Localised Ag+ vibrations at the origin of ultralow thermal conductivity in layered thermoelectric AgCrSe2

    PubMed Central

    Damay, F.; Petit, S.; Rols, S.; Braendlein, M.; Daou, R.; Elkaïm, E.; Fauth, F.; Gascoin, F.; Martin, C.; Maignan, A.

    2016-01-01

    In materials science, the substructure approach consists in imagining complex materials in which a particular property is associated with a distinct structural feature, so as to combine different chosen physical characteristics, which otherwise have little chance to coexist. Applied to thermoelectric materials, it has been used to achieve simultaneously phonon-glass and electron-crystal properties. Mostly studied for its superionic conductivity, AgCrSe2 is a naturally layered compound, which achieves very low thermal conductivity, ~0.4 W.K−1.m−1 at RT (room temperature), and is considered a promising thermoelectric. The Cr atoms of the [CrSe2]∞ layer bear a spin S = 3/2, which orders below TN = 55 K. Here we report low temperature inelastic neutron scattering experiments on AgCrSe2, alongside the magnetic field evolution of its thermal and electrical transport. We observe a very low frequency mode at 3 meV, ascribed to large anharmonic displacements of the Ag+ ions in the [Ag]∞ layer, and 2D magnetic fluctuations up to 3 TN in the chromium layer. The low thermal conductivity of AgCrSe2 is attributed to acoustic phonon scattering by a regular lattice of Ag+ oscillating in quasi-2D potential wells. These findings highlight a new way to achieve localised phonon modes in a perfectly crystalline solid. PMID:27000414

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

    NASA Astrophysics Data System (ADS)

    Neukum, Christoph; Braun, Anika; Azzam, Rafig

    2014-08-01

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

  10. Adsorption and visible light-driven photocatalytic degradation of Rhodamine B in aqueous solutions by Ag@AgBr/SBA-15

    NASA Astrophysics Data System (ADS)

    Hu, Longxing; Yuan, Hang; Zou, Lianpei; Chen, Feiyan; Hu, Xing

    2015-11-01

    A novel composite, Ag@AgBr/SBA-15, was successfully synthesized by dispersion of AgBr on mesoporous silica SBA-15, characterized by several techniques, such as XRD, N2 adsorption-desorption, SEM & EDS, UV-vis spectrum and XPS, and utilized for visible light photocatalytic degradation of dye Rhodamine B (RhB) in aqueous solutions. The results showed that for the various AgBr loadings in the composites, RhB photocatalytic degradation efficiency arrived at the maximum of 77% at 50% loading, or with 50Ag@AgBr/SBA-15. Under the combined mode, the RhB removal reached 88% at 0.3 g/L of 50Ag@AgBr/SBA-15 dosage, 20 mg L-1 of initial RhB concentration, 4.28 of unadjusted initial pH and 20 °C. The RhB photocatalytic degradation followed well with the second-order kinetics, and the increase of the 50Ag@AgBr/SBA-15 dosage, the decrease of the initial RhB concentration and the optimal initial solution pH would be favorable to RhB photocatalytic degradation. The quenching tests demonstrated that the RhB photocatalytic degradation was mainly attributed to the generation of active species such as O2-,bigdot OH and h+. Moreover, the adsorption characteristics of 50Ag@AgBr/SBA-15 were investigated, with its pHpzc of 6.21 acquired and the conclusion that the RhB adsorption isotherm well followed Langmuir model drawn. Additionally, photocatalyst 50Ag@AgBr/SBA-15 can be effectively regenerated with the H2O2 solutions under visible light irradiation, and reused for up to five runs for the degradation of RhB in the presence of visible light, with RhB removal more than 75% and Ag+ leaching undetected for each run.

  11. MO degradation by Ag-Ag2O/g-C3N4 composites under visible-light irradation.

    PubMed

    Wang, Xin; Yan, Jia; Ji, Haiyan; Chen, Zhigang; Xu, Yuanguo; Huang, Liying; Zhang, Qi; Song, Yanhua; Xu, Hui; Li, Huaming

    2016-01-01

    The paper demonstrated the synthesis of Ag-Ag2O/g-C3N4 nanoparticles via a simple liquid phase synthesis path and a facile calcination method. The synthesized Ag-Ag2O/g-C3N4 composites were well characterized by various analytical techniques, such as X-ray diffraction, Fourier transform infrared (FT-IR), X-ray photoemission spectroscopy, transmission electron microscopy, scanning electron microscopy, high resolution transmission electron microscopy, the UV-Vis diffuse-reflectance spectra and transient photocurrent. From the structure and surface characterization, it indicated that Ag-Ag2O/g-C3N4 composites were formed by an effective covering of g-C3N4 with Ag-Ag2O. The results revealed that the 50 wt% nanoparticle had a great effection on the degradation of the methyl orange (MO), which was almost 7.5 times as high as that of g-C3N4. Based on the experimental results, the possible photocatalytic mechanism with photogenerated holes as the main active species was presented.

  12. The Fermilab Main Injector

    SciTech Connect

    Mishra, C.S.

    1992-11-01

    The Fermilab Main Injector is a new 150 GeV proton synchrotron, designed to replace the Main Ring and improve the high energy physics potential of Fermilab. The status of the Fermilab accelerator complex upgrade will be discussed.

  13. Electronic, optical properties and chemical bonding in six novel 1111-like chalcogenide fluorides AMChF (A=Sr, Ba; M=Cu, Ag; and Ch=S, Se, Te) from first principles calculations

    SciTech Connect

    Bannikov, V.V.; Shein, I.R.; Ivanovskii, A.L.

    2012-12-15

    Employing first-principles band structure calculations, we have examined the electronic, optical properties and the peculiarities of the chemical bonding for six newly synthesized layered quaternary 1111-like chalcogenide fluorides SrAgSF, SrAgSeF, SrAgTeF, BaAgSF, BaAgSeF, and SrCuTeF, which are discussed in comparison with some isostructural 1111-like chalcogenide oxides. We found that all of the studied phases AMChF (A=Sr, Ba; M=Cu, Ag; and Ch=S, Se, Te) are semiconductors for which the fitted 'experimental' gaps lie in the interval from 2.23 eV (for SrAgSeF) to 3.07 eV (for SrCuTeF). The near-Fermi states of AMChF are formed exclusively by the valence orbitals of the atoms from the blocks (MCh); thus, these phases belong to the layered materials with 'natural multiple quantum wells'. The bonding in these new AMChF phases is described as a high-anisotropic mixture of ionic and covalent contributions, where ionic M-Ch bonds together with covalent M-Ch and Ch-Ch bonds take place inside blocks (MCh), while inside blocks (AF) and between the adjacent blocks (MCh)/(AF) mainly ionic bonds emerge. - Graphical Abstract: Isoelectronic surface for SrAgSeF and atomic-resolved densities of states for SrAgTeF, and SrCuTeF. Highlights: Black-Right-Pointing-Pointer Very recently six new layered 1111-like chalcogenide fluorides AMChF were synthesized. Black-Right-Pointing-Pointer Electronic, optical properties for AMChF phases were examined from first principles. Black-Right-Pointing-Pointer All these materials are characterized as non-magnetic semiconductors. Black-Right-Pointing-Pointer Bonding is highly anisotropic and includes ionic and covalent contributions. Black-Right-Pointing-Pointer Introduction of magnetic ions in AMChF is proposed for search of novel magnetic materials.

  14. 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.

  15. 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.

  16. Planetary Magnetism

    NASA Technical Reports Server (NTRS)

    Connerney, J. E. P.

    2007-01-01

    The chapter on Planetary Magnetism by Connerney describes the magnetic fields of the planets, from Mercury to Neptune, including the large satellites (Moon, Ganymede) that have or once had active dynamos. The chapter describes the spacecraft missions and observations that, along with select remote observations, form the basis of our knowledge of planetary magnetic fields. Connerney describes the methods of analysis used to characterize planetary magnetic fields, and the models used to represent the main field (due to dynamo action in the planet's interior) and/or remnant magnetic fields locked in the planet's crust, where appropriate. These observations provide valuable insights into dynamo generation of magnetic fields, the structure and composition of planetary interiors, and the evolution of planets.

  17. The geomagnetic main field and the geodynamo

    NASA Technical Reports Server (NTRS)

    Bloxham, Jeremy; Roberts, Paul H.

    1991-01-01

    Information available on the geomagnetic main field and the geodynamo is presented. Attention is given to the process of mapping the magnetic field, the last version of International Geomagnetic Reference Field Model, and maps of the magnetic field at the core-mantle boundary and their interpretation. Particular consideration is given to the existing geodynamo theories, with special relation given to the Braginsky and Meytlis theory of core turbulence in which the turbulence differs fundamentally from classical turbulence of Kolmogorov type.

  18. Siberian snakes for the Fermilab Main Injector

    SciTech Connect

    Anferov, V.A.; Baiod, R.; Courant, E.D.

    1993-04-01

    Appropriate Siberian snakes were designed to maintain the proton beam polarization during acceleration in the Fermilab Main Injector from 8 to 150 GeV. Various snake designs were investigated to find one fitting into the 14 m straight section spaces with the required spin rotation axis and the minimum orbit excursion. The authors studied both cold and warm discrete magnet snakes as well as warm snakes with helical magnets. For the warm discrete magnet snake, obtaining small orbit excursions required a nearly longitudinal snake axis, while axes near {+-}45{degrees} are needed when using two snakes in a ring. The authors found acceptable snakes either by using superconducting magnets or by using warm magnets with a helical dipole field.

  19. The Maine Event

    ERIC Educational Resources Information Center

    McHale, Tom

    2007-01-01

    In this article, the author describes the successful laptop program employed at Mt. Abram High School in Strong, Maine. Through the Maine Learning Technology Initiative, the school has issued laptops to all 36,000 teachers and students in grades 7-8. This program has helped level the playing field for a student population that is 50 percent to 55…

  20. Teaching Main Idea Comprehension.

    ERIC Educational Resources Information Center

    Baumann, James F., Ed.

    Intended to help classroom teachers, curriculum developers, and researchers, this book provides current information on theoretical and instructional aspects of main idea comprehension. Titles and authors are as follows: "The Confused World of Main Idea" (James W. Cunningham and David W. Moore); "The Comprehension of Important…

  1. Maine's Employability Skills Program

    ERIC Educational Resources Information Center

    McMahon, John M.; Wolffe, Karen E.; Wolfe, Judy; Brooker, Carrie

    2013-01-01

    This Practice Report describes the development and implementation of the "Maine Employability Skills Program," a model employment program developed by the Maine Division for the Blind and Visually Impaired (DBVI). The program was designed to support the efforts of the chronically unemployed or underemployed. These consumers were either…

  2. 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.

  3. Fabrication of novel magnetically separable nanocomposites using graphitic carbon nitride, silver phosphate and silver chloride and their applications in photocatalytic removal of different pollutants using visible-light irradiation.

    PubMed

    Mousavi, Mitra; Habibi-Yangjeh, Aziz; Abitorabi, Masoud

    2016-10-15

    In the present study, g-C3N4/Fe3O4/Ag3PO4/AgCl nanocomposites endowed with efficient photocatalytic activity under visible-light irradiation have been successfully prepared by a facile ultrasonic-irradiation method. The prepared samples were characterized by XRD, EDX, AAS, SEM, TEM, UV-vis DRS, FT-IR, TG, PL, and VSM techniques. Rhodamine B, methyl orange, fuchsine, and phenol were selected as pollutants to evaluate photocatalytic activity of the as-prepared samples. Among the samples, the g-C3N4/Fe3O4/Ag3PO4/AgCl (30%) nanocomposite displayed the highest photocatalytic activity. It was found that activity of this nanocomposite in degradation of rhodamine B is nearly 22, 6, and 7.5-times higher than those of the g-C3N4, g-C3N4/Fe3O4/Ag3PO4 (20%), and g-C3N4/Fe3O4/AgCl (30%) samples, respectively. The significant amount of saturation magnetization (8.78emug(-1)) for this nanocomposite indicated that the photocatalyst can be easily separated from the treated solution using a magnetic field. According to the trapping experiments, it was found that holes are main active species, driving the degradation reaction. This work suggests that the quaternary nanocomposite is promising photocatalyst for degradation of organic pollutants under visible-light illumination.

  4. An oil-in-water self-assembly synthesis, characterization and photocatalytic properties of nano Ag@AgCl surface-sensitized K{sub 2}Ti{sub 4}O{sub 9}

    SciTech Connect

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

    2014-12-15

    Highlights: • The plasmatic Ag@AgCl surface-sensitized K{sub 2}Ti{sub 4}O{sub 9} composite photocatalysts. • Ag@AgCl greatly increased visible light absorption for K{sub 2}Ti{sub 4}O{sub 9}. • The photocatalysts exhibited enhanced photocatalytic dye degradation. - Abstract: Nano-sized plasmonic Ag@AgCl surface-sensitized K{sub 2}Ti{sub 4}O{sub 9} composite photocatalysts (hereafter designated as Ag@AgCl/K{sub 2}Ti{sub 4}O{sub 9}) was synthesized via a facile oil-in-water self-assembly method. The photocatalytic activity of the prepared materials for RhB (Rhodamine B) degradation was examined under visible light irradiation. The results reveal that the size of Ag@AgCl, which evenly dispersed on the surface of K{sub 2}Ti{sub 4}O{sub 9}, distributes about 20–50 nm. The UV–vis diffuse reflectance spectra indicate that Ag@AgCl/K{sub 2}Ti{sub 4}O{sub 9} samples have a significantly enhanced optical absorption in 380–700 nm. The photocatalytic activities of the Ag@AgCl/K{sub 2}Ti{sub 4}O{sub 9} samples increase first and then decrease with increasing amount of loading Ag@AgCl and the Ag@AgCl(20 wt.%)/K{sub 2}Ti{sub 4}O{sub 9} sample exhibits the best photocatalytic activity and 94.47% RhB was degraded after irradiation for 2 h. Additionally, studies performed using radical scavengers indicated that O{sub 2}·{sup −} and Cl{sup 0} acted as the main reactive species. The electronic interaction was systematically studied and confirmed by the photo-electrochemical measurements.

  5. Structural and magnetic phase transitions in CeCu6-xTx (T=Ag,Pd)

    SciTech Connect

    Poudel, L.; de la Cruz, C.; Payzant, E. A.; May, A. F.; Koehler, M.; Garlea, V. O.; Taylor, A. E.; Parker, D. S.; Cao, H. B.; McGuire, M. A.; Tian, W.; Matsuda, M.; Jeen, H.; Lee, H. N.; Hong, T.; Calder, S.; Zhou, H. D.; Lumsden, M. D.; Keppens, V.; Mandrus, D.; Christianson, A. D.

    2015-12-15

    The structural and the magnetic properties of CeCu6-xAgx (0≤x≤0.85) and CeCu6-xPdx (0≤x≤0.4) have been studied using neutron diffraction, resonant ultrasound spectroscopy (RUS), x-ray diffraction measurements, and first principles calculations. The structural and magnetic phase diagrams of CeCu6-xAgx and CeCu6-xPdx as a function of Ag/Pd composition are reported. The end member, CeCu6, undergoes a structural phase transition from an orthorhombic (Pnma) to a monoclinic (P21/c) phase at 240 K. In CeCu6-xAgx, the structural phase transition temperature (Ts) decreases linearly with Ag concentration and extrapolates to zero at xS ≈0.1. The structural transition in CeCu6-xPdx remains unperturbed with Pd substitution within the range of our study. The lattice constant b slightly decreases with Ag/Pd doping, whereas a and c increase with an overall increase in the unit cell volume. Both systems, CeCu6-xAgx and CeCu6-xPdx, exhibit a magnetic quantum critical point (QCP), at x≈0.2 and x≈0.05, respectively. Near the QCP, long range antiferromagnetic ordering takes place at an incommensurate wave vector (δ10 δ2), where δ1~0.62,δ2~0.25,x=0.125 for CeCu6-xPdx and δ1~0.64,δ2~0.3,x=0.3 for CeCu6-xAgx. The magnetic structure consists of an amplitude modulation of the Ce moments which are aligned along the c axis of the orthorhombic unit cell.

  6. Effect of Support on the Activity of Ag-based Catalysts for Formaldehyde Oxidation

    PubMed Central

    Zhang, Jianghao; Li, Yaobin; Zhang, Yan; Chen, Min; Wang, Lian; Zhang, Changbin; He, Hong

    2015-01-01

    Ag-based catalysts with different supports (TiO2, Al2O3 and CeO2) were prepared by impregnation method and subsequently tested for the catalytic oxidation of formaldehyde (HCHO) at low temperature. The Ag/TiO2 catalyst showed the distinctive catalytic performance, achieving the complete HCHO conversion at around 95 °C. In contrast, the Ag/Al2O3 and Ag/CeO2 catalysts displayed much lower activity and the 100% conversion was reached at 110 °C and higher than 125 °C, respectively. The Ag-based catalysts were next characterized by several methods. The characterization results revealed that supports have the dramatic influence on the Ag particle sizes and dispersion. Kinetic tests showed that the Ag based catalyst on the TiO2, Al2O3 or CeO2 supports have the similar apparent activation energy of 65 kJ mol−1, indicating that the catalytic mechanism keep immutability over these three catalysts. Therefore, Ag particle size and dispersion was confirmed to be the main factor affecting the catalytic performance for HCHO oxidation. The Ag/TiO2 catalyst has the highest Ag dispersion and the smallest Ag particle size, accordingly presenting the best catalytic performance for HCHO oxidation. PMID:26263506

  7. Enhancement of giant magnetoresistance and oscillation by wave-vector filtering in Fe/Ag/Fe/InAs/Ag

    NASA Astrophysics Data System (ADS)

    Wang, Ziran; Victora, R. H.

    2016-12-01

    The performance of a giant magnetoresistance (GMR) heterostructure Fe/Ag/Fe/InAs/Ag(100) in the current-perpendicular-to-plane geometry is presented. Calculations are based on a realistic tight-banding model with full s p d bands and the recursive Green's function algorithm. Results show that the system's GMR can reach values above 1000%. This GMR enhancement mainly is a result of the wave-vector filtering effect imposed by the InAs layer, restricting conductance within a small region around the Γ point in the 2D Brillouin zone. Calculations also reveal that when the Fermi level sits in the InAs band gap, MR gradually saturates as a function of InAs thickness with a smooth plateau; whereas when the Fermi level is in the InAs conduction band and close to the band bottom, GMR exhibits an oscillatory behavior with a large period. GMR oscillations are also observed with respect to Ag thickness, with oscillation amplitude determined by the Fermi level position relative to the InAs conduction band edge. The oscillation periods in both cases can be well explained by the concept of quantum-well states, and are determined by the spanning vector of the Fermi surface belly of the material whose thickness is varied. The observed GMR oscillations are due to the quantum interference of conduction electrons near the Γ point. The GMR and area-resistance (RA) product profiles at a wide range of Fermi energy positions relative to InAs bands are also compared. Near the GMR peak (with GMR above 1000%) in the conduction band, RA product can be as low as 8.8 Ω μ m2 . This feature of large GMR but small RA product results from the wave-vector filtering effect of doped InAs, and it makes the structure under study distinct from conventional GMR systems (small GMR, small RA) or magnetic tunnel junctions (large GMR, large RA).

  8. The role of Ag on dynamics of superspins in MnFe2- x Ag x O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Aslibeiki, B.; Kameli, P.; Salamati, H.

    2013-02-01

    The effect of dipole-dipole and exchange interactions on dynamics of superspins in a system of MnFe2- x Ag x O4 (where x = 0, 0.1, 0.2, 0.3, and 0.6) nanoparticles has been studied by Ac magnetic susceptibility measurements. Average crystallite size of samples was estimated to be 7 to 4 nm, with respect to the doping level of x = 0-0.6. It was found that the nanoparticles are superparamagnetic at room temperature with almost zero coercivity. Saturation magnetization of samples showed a remarkable reduction by increasing non-magnetic Ag doping level. By decreasing the temperature, a transition to frustrated superspin glass state was observed in all samples. Freezing temperatures of superspins were decreased by increasing the Ag content, as a result of decreasing size of crystallites, magnetization of nanoparticles, and consequently weakening of dipole-dipole interactions. The estimated values of zυ, τ 0, and T 0, using critical slowing down model, justify the observed variation of freezing temperatures. Furthermore it was realized that sensitivity of samples to the variation of applied frequency, an important parameter in hyperthermia based therapy, is affected by magnetic interactions between nanoparticles.

  9. Development of a micro-step voltage-fed actuator with a novel stepper motor for automobile AGS systems.

    PubMed

    Rhyu, Se-Hyun; Lee, Jeong-Jong; Gu, Bon-Gwan; Choi, Byung-Dae; Lim, Jung-Hyuk

    2014-05-05

    This paper presents an improved micro-step voltage-fed actuator for an automobile active grill shutter (AGS) system. A novel structured stepper motor, which contains both the main and auxiliary teeth in the stator, is proposed for the actuator. In a normal permanent magnet (PM) motor coils are generally wound on all the stator teeth, however, in the proposed motor, the winding is only on the main teeth. Because of the absence of coils in the auxiliary teeth, the proposed stepper motor possesses the following advantages: simple structure, lighter weight, smaller volume, and less time consumption. The unique auxiliary poles in the stepper motor supply the flux path to increase the step resolution even without any coils. The characteristics of the proposed stepper motor were investigated using finite element analysis. In particular, the effect of the magnetization distribution of the PM on the motor performance was investigated during the analysis. Cogging torque, which causes noise and vibration issues, was minimized by the tooth-shape optimization. In addition, a micro-step voltage-fed algorithm was implemented for a high-resolution position control. By employing a current close to a sine wave using space vector pulse-width modulation, a high-quality current waveform with a high resolution was obtained. Finally, the proposed prototype was fabricated, and the cogging torque, back-electromotive force, and current characteristics were measured by mounting the prototype on the AGS system. Both the analysis and experimental results validate the performance improvement from the proposed motor and its possible application for the flap control of the AGS system.

  10. Development of a Micro-Step Voltage-Fed Actuator with a Novel Stepper Motor for Automobile AGS Systems

    PubMed Central

    Rhyu, Se-Hyun; Lee, Jeong-Jong; Gu, Bon-Gwan; Choi, Byung-Dae; Lim, Jung-Hyuk

    2014-01-01

    This paper presents an improved micro-step voltage-fed actuator for an automobile active grill shutter (AGS) system. A novel structured stepper motor, which contains both the main and auxiliary teeth in the stator, is proposed for the actuator. In a normal permanent magnet (PM) motor coils are generally wound on all the stator teeth, however, in the proposed motor, the winding is only on the main teeth. Because of the absence of coils in the auxiliary teeth, the proposed stepper motor possesses the following advantages: simple structure, lighter weight, smaller volume, and less time consumption. The unique auxiliary poles in the stepper motor supply the flux path to increase the step resolution even without any coils. The characteristics of the proposed stepper motor were investigated using finite element analysis. In particular, the effect of the magnetization distribution of the PM on the motor performance was investigated during the analysis. Cogging torque, which causes noise and vibration issues, was minimized by the tooth-shape optimization. In addition, a micro-step voltage-fed algorithm was implemented for a high-resolution position control. By employing a current close to a sine wave using space vector pulse-width modulation, a high-quality current waveform with a high resolution was obtained. Finally, the proposed prototype was fabricated, and the cogging torque, back-electromotive force, and current characteristics were measured by mounting the prototype on the AGS system. Both the analysis and experimental results validate the performance improvement from the proposed motor and its possible application for the flap control of the AGS system. PMID:24803193

  11. Studies on properties of Ag/Co0.05Ti0.95O2 random nanocomposite as metamaterials

    NASA Astrophysics Data System (ADS)

    Khorshidi, Zahra; Gholipur, Reza; Bahari, Ali

    2016-10-01

    In this work, random metal-dielectric nanocomposites consisting of Ag nanorods embedded in Co0.05Ti0.95O2 are studied. The aspect ratio of Ag nanorods is about 15, and different contents of Ag nanorods are investigated. The nanocomposites with Ag content exceeding its percolation threshold, show metal-like behavior with negative permittivity. Moreover, in these nanocomposites, Ag nanorods form silver networks with diamagnetic response which combine with the magnetic resonance of ferromagnetic Co0.05Ti0.95O2 particles. The permeability spectra show that CTO-Ag15 33% nanocomposite has strongest diamagnetic behavior. These results indicate that the CTO-Ag15 33% sample is a promising candidate for the double negative materials.

  12. R_transport_matrices of the Fast Extraction Beam (FEB) of the AGS, and Beam Parameters at the Starting point of the AtR Line

    SciTech Connect

    Tsoupas,N.; MacKay, W.W.; Satogata, T.; Glenn, W.; Ahrens, L.; Brown, K.; Gardner, C.; Tanaka, S.

    2008-01-01

    As part of the task to improve and further automate the 'AtR BPM Application' we provide the theoretically calculated R-transport-matrices for the following beam line sections, which are shown schematically in Figure 1: (a) the Fast Extraction Beam section (FEB) of the AGS synchrotron. The FEB section starts at the middle of the GlO-kicker and ends at the middle of the H1 0{_}septum. (b) the Drift Extraction Channel (DEC) section of the AGS synchrotron. The DEC section starts at the middle of the H10{_}septum, continues along the fringe field region of the H11,H12, and H13 AGS main magnets, and ends at the starting point of the AtR line. The knowledge of these R-transport-matrices are needed in order to calculate the beam parameters at the beginning of the AtR line, which in turn, are required to calculate the magnet settings of the U{_}line, that match the U{_}line into the W{_}line. Also by incorporating these R{_}matrices into the model of the AtR line, the G10 kicker and the H10 septum are included in the AtR model therefore one can investigate any 'jitter' of either the GlO{_}kicker or HlO{_}septum by looking at the trajectory of the beam in the AtR line.

  13. Stability of magic planar Ag clusters

    NASA Astrophysics Data System (ADS)

    Chiu, Y. P.; Ou, Y. S.; Chang, Y. R.; Wei, C. M.; Chang, C. S.; Tsong, Tien T.

    2007-03-01

    The spontaneous assembly of atoms and molecules in a system has attracted many research interests and created numerous potential applications. Utilizing the periodic pattern found on the Pb quantum islands, which are grown on the Si(111) surface, we have recently discovered that self-organized Ag planar clusters formed on these templates exhibit enhanced stability at some particular sizes [1]. Existence of the magic atom numbers in these clusters is mainly attributed to the electronic confinement effect. Here, we further explore the strength of these magic clusters subject to the temperature rise and oxygen exposure. Detailed calculations based on ab initio density functional theory have also been performed. The results help establish the relation between the physical and chemical stability of a magic Ag cluster and its size and shape. Ref:[1] Ya-Ping Chiu, Li-Wei Huang, Ching-Ming Wei, Chia-Seng Chang, and Tien-Tzou Tsong, Phys. Rev. Lett. 97, 165504 (2006).

  14. 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.

  15. Structure and physical properties of RE{sub 2}AgGe{sub 3} (RE=Ce, Pr, Nd) compounds

    SciTech Connect

    Sarkar, Sumanta; Mumbaraddi, Dundappa; Halappa, Pramod; Kalsi, Deepti; Rayaprol, Sudhindra; Peter, Sebastian C.

    2015-09-15

    We have synthesized the compounds RE{sub 2}AgGe{sub 3} (RE =Ce, Pr, Nd) by arc melting. The crystal structure obtained from single crystal and powder X-ray diffraction suggests that these compounds crystallize in the α-ThSi{sub 2} structure type. The magnetic susceptibility data of Ce{sub 2}AgGe{sub 3} follows Curie–Weiss (CW) law above 25 K without any magnetic ordering down to 2 K. The effective magnetic moment (μ{sub eff}) was calculated as 2.53 μ{sub B}/Ce and negative Curie paramagnetic temperature (θ{sub p})=−2.4 K hint weak antiferromagnetic coupling among the adjacent spins. Pr{sub 2}AgGe{sub 3} shows a complex magnetic behavior wherein the magnetic susceptibility at field cooled and zero field cooled modes bifurcates at 11.5 K with the latter undergoing a cusp like maxima, probably due to weak ferromagnetic interaction. The θ{sub p} and μ{sub eff} obtained are 4 K and 4.33 μ{sub B}/Pr, respectively. Nd{sub 2}AgGe{sub 3} undergoes multiple magnetic transitions. Temperature dependent resistivity data reveals that three compounds are metallic in nature. - Graphical abstract: The compounds Ce{sub 2}AgGe{sub 3}, Pr{sub 2}AgGe{sub 3} and Nd{sub 2}AgGe{sub 3} have been synthesized by arc melting. X-ray diffraction suggests tetragonal α-ThSi{sub 2} type structure and diverse magnetic properties exhibited in the magnetic measurements. - Highlights: • Two new compounds Ce{sub 2}AgGe{sub 3}, Nd{sub 2}AgGe{sub 3} and known Pr{sub 2}AgGe{sub 3} synthesized by arc melting. • Crystal structure of the compounds derived from X-ray diffraction. • Ce{sub 2}AgGe{sub 3} and Pr{sub 2}AgGe{sub 3} exhibit antiferromagnetic ordering. • Nd{sub 2}AgGe{sub 3} shows multiple magnetic transition with ferrimagnetic like behavior.

  16. Magnetic induction hyperthermia

    NASA Astrophysics Data System (ADS)

    Nikiforov, V. N.

    2007-09-01

    A review of physical principles and experimental data on magnetic hyperthermia are presented. The main principles of magnetic hyperthermia are considered. Results of its application in the therapy of oncology diseases are presented.

  17. Main Pipelines Corrosion Monitoring Device

    NASA Astrophysics Data System (ADS)

    Anatoliy, Bazhenov; Galina, Bondareva; Natalia, Grivennaya; Sergey, Malygin; Mikhail, Goryainov

    2017-01-01

    The aim of the article is to substantiate the technical solution for the problem of monitoring corrosion changes in oil and gas pipelines with use (using) of an electromagnetic NDT method. Pipeline wall thinning under operating conditions can lead to perforations and leakage of the product to be transported outside the pipeline. In most cases there is danger for human life and environment. Monitoring of corrosion changes in pipeline inner wall under operating conditions is complicated because pipelines are mainly made of structural steels with conductive and magnetic properties that complicate test signal passage through the entire thickness of the object under study. The technical solution of this problem lies in monitoring of the internal corrosion changes in pipes under operating conditions in order to increase safety of pipelines by automated prediction of achieving the threshold pre-crash values due to corrosion.

  18. Nonmagnetic 2p-block elements (B, C, N, and O)-doped AgCl for potential halide spintronic applications: A first-principles perspective

    NASA Astrophysics Data System (ADS)

    Lu, Yi-Lin; Dong, Shengjie; Zhou, Wei; Zhao, Hui; Wu, Ping

    2016-08-01

    The structural, electronic, and magnetic properties of 2p-block non-metallic elements (B, C, N, and O)-doped silver chloride were investigated by using ab initio approaches. The results indicate that B, C, N, and O substitution can produce magnetism and the magnetization is mainly from the 2p component of the 2p-block impurities. The total magnetic moments are 2.00, 3.00, 2.00, and 0.98 μB per 2 × 2 × 2 supercell for B, C, N, and O doping, respectively. Semiconducting, half-metallic, and nearly half-metallic magnetic states were generally observed in these cases. The ferromagnetic coupling was observed for B-, N-, and O-doped samples except for C-doped model. Thus, although the calculated magnetic moment of C-doped AgCl is 3.00 μB, the total net magnetic moment should be zero due to the antiferromagnetic order. Several possible explanations have been rationalized from the diversification of the electron count, the hole-mediated p- p and p- d interactions' coupling mechanisms, the elements' electronegativity and the relationship between guest and host atoms.

  19. Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate

    PubMed Central

    Yi, Zao; Niu, Gao; Luo, Jiangshan; Kang, Xiaoli; Yao, Weitang; Zhang, Weibin; Yi, Yougen; Yi, Yong; Ye, Xin; Duan, Tao; Tang, Yongjian

    2016-01-01

    Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the “V”-shaped or “U”-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications. PMID:27586562

  20. Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate

    NASA Astrophysics Data System (ADS)

    Yi, Zao; Niu, Gao; Luo, Jiangshan; Kang, Xiaoli; Yao, Weitang; Zhang, Weibin; Yi, Yougen; Yi, Yong; Ye, Xin; Duan, Tao; Tang, Yongjian

    2016-09-01

    Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the “V”-shaped or “U”-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications.

  1. Ag2S/g-C3N4 composite photocatalysts for efficient Pt-free hydrogen production. The co-catalyst function of Ag/Ag2S formed by simultaneous photodeposition.

    PubMed

    Jiang, Deli; Chen, Linlin; Xie, Jimin; Chen, Min

    2014-03-28

    Without Pt as cocatalyst, the photocatalytic hydrogen evolution activity of graphitic carbon nitride (g-C3N4) or even its composite is normally rather low (<1 μmol h(-1)). Exploring Pt-free cocatalysts to substitute precious Pt is of great importance in the photocatalytic field. In the present work, Ag2S-modified g-C3N4 (Ag2S/g-C3N4) composite photocatalysts were prepared via a simple precipitation method. The results demonstrated that the photocatalytic H2-production activity of g-C3N4 can be remarkably increased by the combination of Ag2S. The optimal Ag2S loading was found to be 5 wt%, giving a H2 production of 10 μmol h(-1), around 100 times that of pure g-C3N4. The enhanced photocatalytic activity can be mainly attributed to the effective charge transfer between g-C3N4 and Ag/Ag2S, of which the latter is formed by simultaneous photodeposition in the photocatalytic H2 evolution reaction and acts as an efficient co-catalyst for the g-C3N4. This work showed the possibility for utilization of Ag2S or Ag/Ag2S as a substitute for Pt in the photocatalytic production of H2 using g-C3N4.

  2. Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    1996-01-01

    AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

  3. Observation of second spin reorientation transition within ultrathin region in Fe films on Ag(001) surface

    SciTech Connect

    Khim, T.-Y.; Shin, M.; Lee, H. E-mail: jhp@postech.ac.kr; Park, B.-G.; Park, J.-H. E-mail: jhp@postech.ac.kr

    2014-06-21

    We acquired direct measurements for in-plane and perpendicular-to-plane magnetic moments of Fe films using an x-ray magnetic circular dichroism technique with increase of the Fe thickness (up to 40 Å) on the Ag(001) surface. Epitaxial Fe/Ag(001) films were grown in situ with the thickness varying from 2 Å to 40 Å, and the magnetic anisotropy was carefully investigated as a function of the film thickness. We found re-entrance of the in-plane magnetic anisotropy of the Fe film in ultrathin region. The results manifest that the epitaxial Fe/Ag(001) film undergoes two distinct spin reorientation transitions from in-plane to out-of-plane at the film thickness t ≈ 9 Å and back to in-plane at t ≈ 18 Å as t increases.

  4. Ag/AgCl reference electrode in thionyl chloride electrolytes

    NASA Astrophysics Data System (ADS)

    Delnick, F. M.; Cieslak, W. R.

    1985-07-01

    Thionyl chloride is the active cathode and electrolyte solvent in Li/SOCl2 primary battery systems. To evaluate charge-transfer reactions in this solvent system, a reference electrode is required. This report describes the fabrication and characterization of Ag/AgCl microreference electrodes that can be used in SOCl2 battery electrolytes.

  5. 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.

  6. Construction of Ag/AgCl nanostructures from Ag nanoparticles as high-performance visible-light photocatalysts

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Liu, Dongzhi; Wang, Tianyang; Li, Wei; Hu, Wenping; Zhou, Xueqin

    2016-11-01

    A combined strategy of in situ oxidation and assembly is developed to prepare Ag/AgCl nanospheres and nanocubes from Ag nanoparticles under room temperature. It is a new facile way to fabricate Ag/AgCl with small sizes and defined morphologies. Ag/AgCl nanospheres with an average size of 80 nm were achieved without any surfactants, while Ag/AgCl nanocubes with a mean edge length of 150 nm were obtained by introduction of N-dodecyl- N, N-dimethyl-2-ammonio-acetate. The possible formation mechanism involves the self-assembly of AgCl nanoparticles, Ostwald ripening and photoreduction of Ag+ into Ag0 by the room light. The as-prepared Ag/AgCl nanospheres and nanocubes exhibit excellent photocatalytic activity and stability toward degradation of organic pollutants under visible-light irradiation. It is demonstrated that Ag/AgCl nanocubes display enhanced photocatalytic activity in comparison with Ag/AgCl nanospheres due to the more efficient charge transfer. This work may pave an avenue to construct various functional materials via the assembly strategy using nanoparticles as versatile building blocks.

  7. Communication: Structure, formation, and equilibration of ensembles of Ag-S complexes on an Ag surface

    SciTech Connect

    Russell, Selena M.; Kim, Yousoo; Liu, Da-Jiang; Evans, J. W.; Thiel, P. A.

    2013-02-15

    We have utilized conditions of very low temperature (4.7 K) and very low sulfur coverage to isolate and identify Ag-S complexes that exist on the Ag(111) surface. The experimental conditions are such that the complexes form at temperatures above the temperature of observation. These complexes can be regarded as polymeric chains of varying length, with an Ag4S pyramid at the core of each monomeric unit. Steps may catalyze the formation of the chains and this mechanism may be reflected in the chain length distribution.

  8. 1 Main Street, Mars

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Located outside StenniSphere, the visitor center at John C. Stennis Space Center, 1 Main Street Mars is a model of how a habitat on Mars might look. Complete with thermometers, scales and clocks set to Martian equivalents, this exhibit shows how very different life on Mars can be.

  9. Main features of meiosis

    SciTech Connect

    1993-12-31

    Chapter 17, outlines the main features of meiosis, beginning with its significance and proceeding through the meiotic stages. Meiosis is the most important modification of mitosis because it is the reduction division that gives rise to the haploid generation in the life cycle. 17 refs., 6 figs.

  10. Ladybugs of Maine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Color images are presented for the 57 species of Coccinellidae, commonly known as ladybugs, that are documented from Maine. Images are displayed in taxonomic order. Information on each species includes its genus-species name, length, and an actual-size silhouette beside a grid matched to the scale...

  11. 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.

  12. AGS Experiments: 1989, 1990, 1991

    SciTech Connect

    Depken, J.C.

    1992-02-01

    This report contains: Experimental areas layout; table of beam parameters and fluxes; experiment schedule ``as run``; proposed 1992 schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS Experiments begin here; and list of AGS Experimenters begins here.

  13. 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…

  14. Formation of the BiAg2 surface alloy on lattice-mismatched interfaces

    NASA Astrophysics Data System (ADS)

    Abd El-Fattah, Z. M.; Lutz, P.; Piquero-Zulaica, I.; Lobo-Checa, J.; Schiller, F.; Bentmann, H.; Ortega, J. E.; Reinert, F.

    2016-10-01

    We report on the growth of a monolayer-thick BiAg2 surface alloy on thin Ag films grown on Pt(111) and Cu(111). Using low energy electron diffraction (LEED), angle resolved photoemission spectroscopy (ARPES), and scanning tunneling microscopy (STM) we show that the surface structure of the 1/3 ML Bi/x -ML Ag/Pt(111) system (x ≥2 ) is strongly affected by the annealing temperature required to form the alloy. As judged from the characteristic (√{3 }×√{3 } )R 30∘ LEED pattern, the BiAg2 alloy is partially formed at room temperature. A gentle, gradual increase in the annealing temperatures successively results in the formation of a pure BiAg2 phase, a combination of that phase with a (2 ×2 ) superstructure, and finally the pure (2 ×2 ) phase, which persists at higher annealing temperatures. These results complement recent work reporting the (2 ×2 ) as a predominant phase, and attributing the absence of BiAg2 alloy to the strained Ag/Pt interface. Likewise, we show that the growth of the BiAg2 alloy on similarly lattice-mismatched 1 and 2 ML Ag-Cu(111) interfaces also requires a low annealing temperature, whilst higher temperatures result in BiAg2 clustering and the formation of a BiCu2 alloy. The demonstration that the BiAg2 alloy can be formed on thin Ag films on different substrates presenting a strained interface has the prospect of serving as bases for technologically relevant systems, such as Rashba alloys interfaced with magnetic and semiconductor substrates.

  15. Maine coast winds

    SciTech Connect

    Avery, Richard

    2000-01-28

    The Maine Coast Winds Project was proposed for four possible turbine locations. Significant progress has been made at the prime location, with a lease-power purchase contract for ten years for the installation of turbine equipment having been obtained. Most of the site planning and permitting have been completed. It is expect that the turbine will be installed in early May. The other three locations are less suitable for the project, and new locations are being considered.

  16. COBRA Main Engine Project

    NASA Technical Reports Server (NTRS)

    Snoddy, Jim; Sides, Steve; Lyles, Garry M. (Technical Monitor)

    2002-01-01

    The COBRA (CO-Optimized Booster for Reusable Applications) project include the following: 1. COBRA main engine project team. 2. COBRA and RLX cycles selected. 3. COBRA proto-type engine approach enables mission success. 4. COBRA provides quick, low cost demo of cycle and technologies. 5. COBRA cycle I risk reduction supports. 6. Achieving engine safety. 6. RLX cycle I risk reduction supports. 7. Flight qualification. 9. Life extension engine testing.

  17. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1992-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependent FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers is contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the ransition temperature.

  18. Plasmonic Ag2MoO4/AgBr/Ag composite: Excellent photocatalytic performance and possible photocatalytic mechanism

    NASA Astrophysics Data System (ADS)

    Wang, Zhongliao; Zhang, Jinfeng; Lv, Jiali; Dai, Kai; Liang, Changhao

    2017-02-01

    Plasmonic Ag2MoO4/AgBr/Ag composite is fabricated by in-situ ion exchange and reduction methods at room temperature. The samples are characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance (DRS), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM) and photoluminescence (PL) measurements. The results show that butterfly-like Ag2MoO4 nanosheets served as the precursor, and Ag2MoO4/AgBr/Ag is formed in phase transformation with MoO42- displaced by Br-. The ternary Ag2MoO4/AgBr/Ag composite photocatalysts show greatly enhanced photocatalytic activity in photodegrading methylene blue (MB) under visible light irradiation compared with AgBr and Ag2MoO4. The pseudo-first-order rate constant kapp of Ag2MoO4/AgBr/Ag is 0.602 min-1, which is 11.6 and 18.3 times as high as that of AgBr and Ag2MoO4, respectively. Meanwhile, the efficiency of degradation still kept 90% after ten times cyclic experiments. Eventually, possible photocatalytic mechanism was proposed.

  19. Enhanced phase stabilization of CoPt in the presence of Ag

    NASA Astrophysics Data System (ADS)

    Sehdev, Neeru; Medwal, Rohit; Annapoorni, S.

    2011-08-01

    We report the synthesis of CoPt and CoPt-Ag nanoparticles by the simultaneous reduction of platinum(II) acetylacetonate (Pt(acac)2), cobalt(II)acetylacetonate (Co(acac)2), and silver nitrate (AgNO3) (for CoPt-Ag) in the presence of poly(N-vinyl-2-pyrrolidone) (PVP). Here the changes in the structural and magnetic properties of these nanoparticles subjected to heat treatment and the effect of adding silver to CoPt in comparison to pure CoPt have been investigated. TEM observations reveal a narrow size distribution with particle diameter of about 2-3 nm. The XRD studies reveal a disordered fcc phase for the as synthesized nanoparticles which after annealing at higher temperatures show peaks corresponding to an ordered L10 phase. The structural phase transition is also followed by enhanced magnetic properties. The magnetic measurements show the transition of a magnetically soft alloy to a magnetically hard material with a maximum coercivity of ˜1 T after annealing at 700 °C. The addition of silver (Ag) to CoPt alloy induces a reduction in the ordering temperature by 100 °C compared to pure CoPt, with an increased coercivity of 1.2 T. Such thermally stable and structurally ordered hard magnetic nanoparticles are promising candidates for magnetic storage applications.

  20. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1990-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependent FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers is contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the transition temperature. During the next project period the P.I. proposes to (1) extend the variable frequency FMR measurements to low temperature, where extremely large interface anisotropies are known to obtain in Ni/Mo and Ni/V and are proposed to exist in Ni/W; (2) obtain accurate dc anisotropies via a novel, variable temperature torque magnetometer currently under construction; (3) expand upon his initial findings in Fe/Cu multilayer investigations; (4) begin anisotropy investigations on Co/Ag and CoCr/Ag multilayers where the easy magnetization direction depends upon the Cr concentration; (4) make and characterize Bi based superconductors according to resistivity, thermal conductivity and thermoelectric power and construct YBaCuO based superconducting loop-gap'' resonators for use in his magnetic resonance work.

  1. Magnetic multilayer interface anisotropy

    SciTech Connect

    Pechan, M.J.

    1991-01-01

    Ni/Mo and Ni/V multilayer magnetic anisotropy has been investigated as a function of Ni layer thickness, frequency and temperature. Variable frequency ferromagnetic resonance (FMR) measurements show, for the first time, significant frequency dependence associated with the multilayer magnetic anisotropy. The thickness dependence allows one to extract the interface contribution from the total anisotropy. Temperature dependant FMR (9 GHz) and room temperature magnetization indicate that strain between Ni and the non-magnetic layers if contributing significantly to the source of the interface anisotropy and the state of the interfacial magnetization. In order to examine the interface properties of other transition metal multilayer systems, investigations on Fe/Cu are underway and CoCr/Ag is being proposed. ESR measurements have been reported on Gd substituted YBaCuO superconductors and a novel quasi-equilibrium method has been developed to determine quickly and precisely the transition temperature. During the next project the P.I. proposes to (1) extend the variable frequency FMR measurements to low temperature, where extremely large interface anisotropies are known to obtain in Ni/Mo and Ni/V and are proposed to exist in Ni/W; (2) obtain accurate dc anisotropies via a novel, variable temperature torque magnetometer currently under construction; (3) expand upon his initial findings in Fe/Cu multilayer investigations; (4) begin anisotropy investigations on Co/Ag and CoCr/Ag multilayers where the easy magnetization direction depends upon the Cr concentration; (4) make and characterize Bi based superconductors according to resistivity, thermal conductivity and thermoelectric power and construct YBaCuO based superconducting loop-gap'' resonators for use in his magnetic resonance work. 2 figs.

  2. Exploring Main Belt Asteroids

    NASA Astrophysics Data System (ADS)

    Sykes, M. V.; Larson, S. M.; Whiteley, R.; Fink, U.; Jedicke, R.; Emery, J.; Fevig, R.; Kelley, M.; Harris, A. W.; Ostro, S.; Reed, K.; Binzel, R. P.; Rivkin, A.; Magri, C.; Bottke, W.; Durda, D.; Walker, R.; Davis, D.; Hartmann, W. K.; Sears, D.; Yano, H.; Granahan, J.; Storrs, A.; Bus, S. J.; Bell, J. F.; Tholen, D.; Cellino, A.

    2001-11-01

    Terrestrial planet formation in the main asteroid belt was interrupted when growing protoplanets became sufficiently massive to gravitationally perturb the local population, causing bodies to collide with increased energy, thus ending accretion and commencing fragmentation and disruption. Few of these protoplanets are thought to have survived unshattered (e.g., Ceres, Vesta, Pallas), leaving a main belt population dominated by fragments of fragments, and significantly depleted of mass as a consequence of dynamical scattering. Yet, these fragments retain a record of the early steps of planet formation and evolution, as well as a record of early solar system conditions and the primordial composition gradient in that region. By exploring main belt asteroids through groundbased observations and spacecraft, modeling and theoretical work, we seek ultimately to recover this information. A single mission to a single target is not sufficient to address, in isolation, these questions. They require a foundation of robust, broad, and continuing groundbased, theoretical, and modeling programs. Such work is funded at a small fraction of a typical mission cost through the NASA Research and Analysis Program. Therefore, within the context of planetary decadal study recommendations to NASA, highest priority needs to be given to maintaining and growing a healthy R&A program over the next ten years and beyond. Missions also have an important role to play. An Earth orbiting remote sensing mission needs to be considered as a means of collecting important data for a large fraction of all main belt asteroids above a sub-kilometer diameter (while also realizing synergistic benefits to astrophysics). Missions to specific main belt targets can provide important new insights and leverage new understanding of existing data, models, and theories, but target definition (and corresponding instrument complement) is critical and must be based on our existing knowledge of these very diverse objects

  3. Radiochemical synthesis of 105gAg-labelled silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Ichedef, C.; Simonelli, F.; Holzwarth, U.; Bagaria, J. Piella; Puntes, V. F.; Cotogno, G.; Gilliland, D.; Gibson, N.

    2013-11-01

    A method for synthesis of radiolabelled silver nanoparticles is reported. The method is based on proton activation of silver metal powder, enriched in 107Ag, with a 30.7 MeV proton beam. At this proton energy 105gAg is efficiently created, mainly via the 107Ag(p,3n)105Cd → 105gAg reaction. 105gAg has a half-life of 41.29 days and emits easily detectable gamma radiation on decay to 105Pd. This makes it very useful as a tracing radionuclide for experiments over several weeks or months. Following activation and a period to allow short-lived radionuclides to decay, the powder was dissolved in concentrated nitric acid in order to form silver nitrate (AgNO3), which was used to synthesise radiolabelled silver nanoparticles via the process of sodium borohydride reduction. For comparison, non-radioactive silver nanoparticles were synthesised using commercially supplied AgNO3 in order to check if the use of irradiated Ag powder as a starting material would alter in any way the final nanoparticle characteristics. Both nanoparticle types were characterised using dynamic light scattering, zeta-potential and X-ray diffraction measurements, while additionally the non-radioactive samples were analysed by transmission electron microscopy and UV-Vis spectrometry. A hydrodynamic diameter of about 16 nm was determined for both radiolabelled and non-radioactive nanoparticles, while the electron microscopy on the non-radioactive samples indicated that the physical size of the metal NPs was (7.3 ± 1.4) nm.

  4. Negligible particle-specific toxicity mechanism of silver nanoparticles: the role of Ag+ ion release in the cytosol.

    PubMed

    De Matteis, Valeria; Malvindi, Maria Ada; Galeone, Antonio; Brunetti, Virgilio; De Luca, Elisa; Kote, Sachin; Kshirsagar, Prakash; Sabella, Stefania; Bardi, Giuseppe; Pompa, Pier Paolo

    2015-04-01

    Toxicity of silver nanoparticles (AgNPs) is supported by many observations in literature, but no mechanism details have been proved yet. Here we confirm and quantify the toxic potential of fully characterized AgNPs in HeLa and A549 cells. Notably, through a specific fluorescent probe, we demonstrate the intracellular release of Ag(+) ions in living cells after nanoparticle internalization, showing that in-situ particle degradation is promoted by the acidic lysosomal environment. The activation of metallothioneins in response to AgNPs and the possibility to reverse the main toxic pathway by Ag(+) chelating agents demonstrate a cause/effect relationship between ions and cell death. We propose that endocytosed AgNPs are degraded in the lysosomes and the release of Ag(+) ions in the cytosol induces cell damages, while ions released in the cell culture medium play a negligible effect. These findings will be useful to develop safer-by-design nanoparticles and proper regulatory guidelines of AgNPs. From the clinical editor: The authors describe the toxic potential of silver nanoparticles (AgNP) in human cancer cell lines. Cell death following the application of AgNPs is dose-dependent, and it is mostly due to Ag+ ions. Further in vivo studies should be performed to gain a comprehensive picture of AgNP-toxicity in mammals.

  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. Aquarius Main Structure Configuration

    NASA Technical Reports Server (NTRS)

    Eremenko, Alexander

    2012-01-01

    The Aquarius/SAC-D Observatory is a joint US-Argentine mission to map the salinity at the ocean surface. This information is critical to improving our understanding of two major components of Earth's climate system - the water cycle and ocean circulation. By measuring ocean salinity from space, the Aquarius/SAC-D Mission will provide new insights into how the massive natural exchange of freshwater between the ocean, atmosphere and sea ice influences ocean circulation, weather and climate. Aquarius is the primary instrument on the SAC-D spacecraft. It consists of a Passive Microwave Radiometer to detect the surface emission that is used to obtain salinity and an Active Scatterometer to measure the ocean waves that affect the precision of the salinity measurement. The Aquarius Primary Structure houses instrument electronics, feed assemblies, and supports a deployable boom with a 2.5 m Reflector, and provides the structural interface to the SAC-D Spacecraft. The key challenge for the Aquarius main structure configuration is to satisfy the needs of component accommodations, ensuring that the instrument can meet all operational, pointing, environmental, and launch vehicle requirements. This paper describes the evolution of the Aquarius main structure configuration, the challenges of balancing the conflicting requirements, and the major configuration driving decisions and compromises.

  7. 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.

  8. A tool for model based diagnostics of the AGS Booster

    SciTech Connect

    Luccio, A.

    1993-12-31

    A model-based algorithmic tool was developed to search for lattice errors by a systematic analysis of orbit data in the AGS Booster synchrotron. The algorithm employs transfer matrices calculated with MAD between points in the ring. Iterative model fitting of the data allows one to find and eventually correct magnet displacements and angles or field errors. The tool, implemented on a HP-Apollo workstation system, has proved very general and of immediate physical interpretation.

  9. Physical properties of FePt nanocomposite doped with Ag atoms: First-principles study

    NASA Astrophysics Data System (ADS)

    Jia, Yong-Fei; Shu, Xiao-Lin; Xie, Yong; Chen, Zi-Yu

    2014-07-01

    L10 FePt nanocomposite with high magnetocrystalline anisotropy energy has been extensively investigated in the fields of ultra-high density magnetic recording media. However, the order—disorder transition temperature of the nanocomposite is higher than 600 °C, which is a disadvantage for the use of the material due to the sustained growth of FePt grain under the temperature. To address the problem, addition of Ag atoms has been proposed, but the magnetic properties of the doped system are still unclear so far. Here in this paper, we use first-principles method to study the lattice parameters, formation energy, electronic structure, atomic magnetic moment and order—disorder transition temperature of L10 FePt with Ag atom doping. The results show that the formation energy of a Ag atom substituting for a Pt site is 1.309 eV, which is lower than that of substituting for an Fe site 1.346 eV. The formation energy of substituting for the two nearest Pt sites is 2.560 eV lower than that of substituting for the further sites 2.621 eV, which indicates that Ag dopants tend to segregate L10 FePt. The special quasirandom structures (SQSs) for the pure FePt and the FePt doped with two Ag atoms at the stable Pt sites show that the order—disorder transition temperatures are 1377 °C and 600 °C, respectively, suggesting that the transition temperature can be reduced with Ag atom, and therefore the FePt grain growth is suppressed. The saturation magnetizations of the pure FePt and the two Ag atoms doped FePt are 1083 emu/cc and 1062 emu/cc, respectively, indicating that the magnetic property of the doped system is almost unchanged.

  10. Shape-controlled fabrication of magnetite silver hybrid nanoparticles with high performance magnetic hyperthermia.

    PubMed

    Ding, Qi; Liu, Dongfang; Guo, Dawei; Yang, Fang; Pang, Xingyun; Che, Renchao; Zhou, Naizhen; Xie, Jun; Sun, Jianfei; Huang, Zhihai; Gu, Ning

    2017-04-01

    Superparamagnetic Fe3O4 nanoparticles (NPs)-based hyperthermia is a promising non-invasive approach for cancer therapy. However, the heat transfer efficiency of Fe3O4 NPs is relative low, which hinders their practical clinical applications. Therefore, it is promising to improve the magnetic hyperthermia efficiency by exploring the higher performance magnetic NPs-based hybrid nanostructures. In the current study, it presents a straightforward in situ reduction method for the shape-controlled preparation of magnetite (Fe3O4) silver (Ag) hybrid NPs designed as magnetic hyperthermia heat mediators. The magnetite silver hybrid NPs with core-shell (Fe3O4@Ag) or heteromer (Fe3O4-Ag) structures exhibited a higher biocompatibility with SMMC-7721 cells and L02 cells than the individual Ag NPs. Importantly, in the magnetic hyperthermia, with the exposure to alternating current magnetic field, the Fe3O4@Ag and Fe3O4-Ag hybrid NPs indicated much better tumor suppression effect against SMMC-7721 cells than the individual Fe3O4 NPs in vitro and in vivo. These results demonstrate that the hybridisation of Fe3O4 and Ag NPs could greatly enhance the magnetic hyperthermia efficiency of Fe3O4 NPs. Therefore, the Fe3O4@Ag and Fe3O4-Ag hybrid NPs can be used to be as high performance magnetic hyperthermia mediators based on a simple and effective preparation approach.

  11. Main Oxidizer Valve Design

    NASA Technical Reports Server (NTRS)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  12. Charge-to-Spin Conversion and Spin Diffusion in Bi/Ag Bilayers Observed by Spin-Polarized Positron Beam

    NASA Astrophysics Data System (ADS)

    Zhang, H. J.; Yamamoto, S.; Gu, B.; Li, H.; Maekawa, M.; Fukaya, Y.; Kawasuso, A.

    2015-04-01

    Charge-to-spin conversion induced by the Rashba-Edelstein effect was directly observed for the first time in samples with no magnetic layer. A spin-polarized positron beam was used to probe the spin polarization of the outermost surface electrons of Bi /Ag /Al2O3 and Ag /Bi /Al2O3 when charge currents were only associated with the Ag layers. An opposite surface spin polarization was found between Bi /Ag /Al2O3 and Ag /Bi /Al2O3 samples with the application of a charge current in the same direction. The surface spin polarizations of both systems decreased exponentially with the outermost layer thickness, suggesting the occurrence of spin diffusion from the Bi/Ag interface to the outermost surfaces. This work provides a new technique to measure spin diffusion length.

  13. Air-cooled trim dipoles for the Fermilab Main Injector

    SciTech Connect

    Harding, D. J.; Chester, N. S.; Garvey, J. D.; Krafczyk, G. E.; Makarov, A. I.; Terechkine, I.; Yarba, V. A.

    1997-05-01

    New horizontal and vertical trim dipoles have been designed for the Fermilab Main Injector (FMI) and are being assembled in the Fermilab Technical Division. Magnets are 42.6 cm in length (30.5 cm steel length) and have similar cross-section dimensions. The horizontal (vertical) magnet gap is 50.8 mm (127 mm) and the target integrated strength is 0.072 T*m (0.029 T*m). The major design effort lay in making air cooling possible for these magnets. This report presents the magnets` thermal and magnetic properties and discusses the limitation on excitation current.

  14. Orbital Orderings and Optical Conductivity in Cs2AgF4

    NASA Astrophysics Data System (ADS)

    Zhang, Min-Ping; Qian, Yu-Min; Wang, Guang-Tao

    The Jahn-Teller (JT) distortion induced orbital order and optical-conductivity in Cs2AgF4 are investigated by first-principle calculations. Cs2AgF4 contains 4d9 Ag2+, similar to 3d9 Cu2+ of La2CuO4. Although Cs2AgF4 is an isoelectronic analogue of La2CuO4, their magnetisms are radically different: La2CuO4 is antiferromagnetism (AFM), while Cs2AgF4 is proposed to be ferromagnetism (FM) based on recent neutron scattering data. The great difference can be understood from the JT distortions in the AgF6 octahedron, which favors the formation of staggered orbital order of dz2-x2 and dz2-y2. Such orbital order favors FM state, according to Goodenough-Kanamori Rules. We find when the JT distortion is larger than 0.03, the ground state of Cs2AgF4 is AFM. This antiferromagnetism might induce superconductivity, just as La2CuO4. In order to confirm such orbital order of Ag, we present the calculated optical-conductivity, which could be examined by experiment.

  15. Matching the BtA line to the bare-AGS (Part 1)

    SciTech Connect

    Tsoupas,N.; Glenn, J. W.; Huan, H.; MacKay, W. W.; Raparia, D.; Zeno, K.

    2008-11-01

    The Booster to AGS (BtA) transfer line [Ref for BtA line] transports the beam bunches from the AGS-Booster to the AGS synchrotron, and also matches the beam parameters ({beta}{sub x,y}, {alpha}{sub x,y}) and dispersion functions ({eta}{sub x,y}, {eta}{prime}{sub x,y}) of the transported beam to the corresponding quantities of the circulating beam in AGS, at the AGS injection point. In this technical note we describe in details, the calculations of the matching procedure of the BtA line to the bare-AGS, and provide magnet settings for the MAD-model of the BtA transfer line which is 'matched' to the bare-AGS. In a separate but more concise technical note (Part II) we will present results on the beam optics of the BtA beam line which is 'matched' to the AGS with two helical snakes.

  16. Role of the upper branch of the hour-glass magnetic spectrum in the formation of the main kink in the electronic dispersion of high-Tc cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Geffroy, Dominique; Chaloupka, Jiří; Dahm, Thomas; Munzar, Dominik

    2016-04-01

    We investigate the electronic dispersion of the high-Tc cuprate superconductors using the fully self-consistent version of the phenomenological model, where charge planar quasiparticles are coupled to spin fluctuations. The inputs we use, the underlying (bare) band structure and the spin susceptibility χ , are extracted from fits of angle-resolved photoemission and inelastic neutron scattering data of underdoped YBa2Cu3O6.6 by T. Dahm and coworkers [Nat. Phys. 5, 217 (2009), 10.1038/nphys1180]. Our main results are as follows: (i) We have confirmed the finding by Dahm and coworkers that the main nodal kink is, for the present values of the input parameters, determined by the upper branch of the hourglass of χ . We demonstrate that the properties of the kink depend qualitatively on the strength of the charge-spin coupling. (ii) The effect of the resonance mode of χ on the electronic dispersion strongly depends on its kurtosis in the quasimomentum space. A low (high) kurtosis implies a negligible (considerable) effect of the mode on the dispersion in the near-nodal region. (iii) The energy of the kink decreases as a function of the angle θ between the Fermi surface cut and the nodal direction, in qualitative agreement with recent experimental observations. We clarify the trend and make a specific prediction concerning the angular dependence of the kink energy in underdoped YBa2Cu3O6.6 .

  17. [Main parasitic skin disorders].

    PubMed

    Bernigaud, C; Monsel, G; Delaunay, P; Do-Pham, G; Foulet, F; Botterel, F; Chosidow, O

    2017-01-01

    Cutaneous parasitic skin diseases are frequent in human pathology. There are few reliable epidemiological data on the prevalence and/or incidence of such diseases. Skin parasites are cosmopolitan but their global distribution is heterogenous; prevalence is especially high in subtropical and tropical countries. They are mainly due to arthropods (insects and mites). Many species of parasites are involved, explaining the diversity of their clinical signs. The most common are caused by ectoparasites such as scabies or pediculosis (head lice, body lice and pubic lice). Clinical signs may be related to the penetration of the parasite under the skin, its development, the inoculation of venom or allergic symptoms. Diagnosis can be easy when clinical signs are pathognomonic (e.g. burrows in the interdigital web spaces in scabies) or sometimes more difficult. Some epidemiological characteristics (diurnal or nocturnal bite, seasonality) and specific clinical presentation (single or multiple bites, linear or grouped lesions) can be a great diagnostic help. Modern non-invasive tools (dermoscopy or confocal microscopy) will play an important role in the future but the eye and experience of the specialist (dermatologist, parasitologist, infectious disease specialist or entomologist) remains for the time the best way to guide or establish a diagnosis. For most skin parasites, therapeutic proposals are rarely based on studies of high level of evidence or randomized trials but more on expert recommendations or personal experience.

  18. Magnetostructural phase transition assisted by temperature in Ag-αMnO2: a density functional theory study.

    PubMed

    Ochoa, Francisco Sánchez; Huang, Zhiwei; Tang, Xingfu; Cocoletzi, Gregorio Hernández; Springborg, Michael

    2016-03-14

    A crystalline material formed by parallel chains of silver atoms inside one-dimensional tunnels of hollandite manganese dioxide, Ag-αMnO2, is investigated through first-principles total energy calculations. Two different magnetic phases have been identified; one structure containing linear Ag chains with an antiferromagnetic ordering in the direction perpendicular to the MnO2 tunnels for T = 0 K (I4/m) and another configuration with zigzag Ag chains in a non-magnetic regime for higher temperatures (P21/c). According to phonon dispersions, both structures are stable. On the other hand, the structure with linear Ag chains in the non-magnetic state is unstable. A critical temperature of Tc≃ 125 K for the magnetostructural phase transition between the two stable structures I4/m and P21/c is predicted.

  19. Improvement of microwave magnetic properties by inserting nonmagnetic layer

    NASA Astrophysics Data System (ADS)

    Li, Xiaoting; An, Chao; Wang, Zhen; Xu, Chunlong; Shi, Gang; Wang, Jinguo; Hou, Zhaoyang; Xi, Li

    2017-01-01

    Co/NM (nonmagnetic Ag and SiO2)/Co sandwich structure films with different thicknesses of NM were fabricated on Si(111) substrate via oblique radio frequency sputtering. With increasing thickness of nonmagnetic Ag (tAg), in-plane magnetic anisotropy field Hk initially increased from 100 Oe of tAg = 0 nm to 220 Oe of tAg = 1.5 nm, and then decreased when tAg > 1.5 nm. Resonance frequency showed the same tendency with maximum 5.2 GHz when tAg = 1.5 nm. Damp factor increased from 0.02 for tAg = 0-0.08 for tAg = 2.0 nm. The same result was observed in inserting oxide nonmagnetic SiO2 layer. This can be attributed to the competition between interface energy and exchange coupling energy.

  20. 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.

  1. The effect of dielectric constants on noble metal/semiconductor SERS enhancement: FDTD simulation and experiment validation of Ag/Ge and Ag/Si substrates.

    PubMed

    Wang, Tao; Zhang, Zhaoshun; Liao, Fan; Cai, Qian; Li, Yanqing; Lee, Shuit-Tong; Shao, Mingwang

    2014-02-11

    The finite-difference time-domain (FDTD) method was employed to simulate the electric field distribution for noble metal (Au or Ag)/semiconductor (Ge or Si) substrates. The simulation showed that noble metal/Ge had stronger SERS enhancement than noble metal/Si, which was mainly attributed to the different dielectric constants of semiconductors. In order to verify the simulation, Ag nanoparticles with the diameter of ca. 40 nm were grown on Ge or Si wafer (Ag/Ge or Ag/Si) and employed as surface-enhanced Raman scattering substrates to detect analytes in solution. The experiment demonstrated that both the two substrates exhibited excellent performance in the low concentration detection of Rhodamine 6G. Besides, the enhancement factor (1.3 × 10(9)) and relative standard deviation values (less than 11%) of Ag/Ge substrate were both better than those of Ag/Si (2.9 × 10(7) and less than 15%, respectively), which was consistent with the FDTD simulation. Moreover, Ag nanoparticles were grown in-situ on Ge substrate, which kept the nanoparticles from aggregation in the detection. To data, Ag/Ge substrates showed the best performance for their sensitivity and uniformity among the noble metal/semiconductor ones.

  2. Diamondoid Structure in a Metal-Organic Framework of Fe4 Single-Molecule Magnets.

    PubMed

    Rigamonti, Luca; Cotton, Carri; Nava, Andrea; Lang, Heinrich; Rüffer, Tobias; Perfetti, Mauro; Sorace, Lorenzo; Barra, Anne-Laure; Lan, Yanhua; Wernsdorfer, Wolfgang; Sessoli, Roberta; Cornia, Andrea

    2016-09-12

    A 3D metal-organic framework (MOF) having single-molecule magnet (SMM) linkers was prepared in crystalline form by using a tetrairon(III) complex functionalised with two divergent pyridyl groups, namely [Fe4 (pPy)2 (dpm)6 ] (1; H3 pPy=2-(hydroxymethyl)-2-(pyridin-4-yl)propane-1,3-diol, Hdpm=dipivaloylmethane). Reaction of 1 with silver(I) perchlorate afforded {[Fe4 (pPy)2 (dpm)6 ]2 Ag}ClO4 (2), which crystallises in a cubic face-centred lattice and exhibits two interlocked diamondoid networks. In 2, the SMMs act as linear ditopic synthons, and silver(I) ions as tetrahedral nodes coordinated by four pyridyl nitrogen atoms. The magnetic properties of 1 (S=5 and D≈-0.4 cm(-1) in the ground spin state) are largely preserved in 2, which shows slow magnetic relaxation with an anisotropy barrier of Ueff /kB =11.46(10) K in zero field and 14.25(8) K in an applied field of 1 kOe. However, crystal symmetry triggers highly noncollinear magnetic anisotropy contributions oriented at 109.47° from each other along the threefold axes of AgN4 tetrahedra, a unique scenario fully confirmed by a single-crystal cantilever torque magnetometry investigation. Magnetisation curves down to 0.03 K demonstrated the occurrence of a wide hysteresis loop when the magnetic field was swept along one of the four Ag-N bonds. By symmetry, the crystalline compound can then be persistently magnetised parallel or antiparallel to the four main diagonals of the unit cell, although the crystals have no overall second-order anisotropy.

  3. Ag-Pd-Si (009)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Ag-Pd-Si (009)' with the content:

  4. Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites

    NASA Astrophysics Data System (ADS)

    Prakash, Jai; Kumar, Promod; Harris, R. A.; Swart, Chantel; Neethling, J. H.; Janse van Vuuren, A.; Swart, H. C.

    2016-09-01

    We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples.

  5. Approaches for Controlled Ag(+) Ion Release: Influence of Surface Topography, Roughness, and Bactericide Content.

    PubMed

    Sukhorukova, I V; Sheveyko, A N; Shvindina, N V; Denisenko, E A; Ignatov, S G; Shtansky, D V

    2017-02-01

    Silver is the most famous bactericidal element known from ancient times. Its antibacterial and antifungal effects are typically associated with the Ag ionization and concentration of Ag(+) ions in a bacterial culture. Herein we thoroughly studied the influence of surface topography and roughness on the rate of Ag(+) ion release. We considered two types of biocompatible and bioactive TiCaPCON-Ag films with 1 and 2 at. % of Ag and nine types of Ti surfaces with an average roughness varying in the range from 5.4 × 10(-2) to 12.6 μm and different topographic features obtained through polishing, sandblasting, laser treatment, and pulsed electrospark deposition. It is demonstrated that the Ag(+) ion release rates do not depend on the Ag content in the films as the main parameter, and it is other factors, such as the state of Ag agglomeration, surface topography and roughness, as well as kinetics of surface oxidation, that play a critical role. The obtained results clearly show a synergistic effect of the Ag content in the film and surface topography and roughness on Ag(+) ion release. By changing the surface topographical features at a constant content of bactericidal element, we showed that the Ag(+) ion release can be either accelerated by 2.5 times or almost completely suppressed. Despite low Ag(+) ion concentration in physiological solution (<40 ppb), samples with specially fabricated surface reliefs (flakes or holes) showed a pronounced antibacterial effect already after 3 h of immersion in E. coli bacterial culture. Thus, our results open up new possibilities for the production of cost-effective, scalable, and biologically safe implants with pronounced antibacterial characteristics for future applications in the orthopedic field.

  6. Size evolution of nanomagnetic particles and magnetotransport properties of (Co90Fe10)20Ag80 nanogranular films: influence of Cu80Ag15Au5 underlayer

    NASA Astrophysics Data System (ADS)

    Öksüzoğlu, Ramis Mustafa; Meshcheryakov, Vladimir F.; Ayas, Erhan

    2012-06-01

    The influence of (Co90Fe10)20Ag80 film thickness and of Cu80Ag15Au5 underlayer on nanomagnetic, magnetotransport and structural properties of (Co90Fe10)20Ag80 nanogranular films prepared by ultra-high vacuum ion beam sputtering technique have been investigated using X-ray diffraction, X-ray reflectivity and vibrating sample magnetometer. Films indicate a superparamagnetic behavior. The evolution of the magnetic particle size in (Co90Fe10)20Ag80 film with different thicknesses was calculated by fit of magnetization curves using Langevin equation. A parallel resistance model has been used to determine particle size distribution. The average (mean) particle sizes range from 1.6 to 2.1 nm. A linear dependence of giant magnetoresistance (GMR) on the particle size has been found. This result is also supported by the observed linear correlation between the square root of the effective magnetization and the particle size. Furthermore, a linear correlation between the square of GMR and the distance between particles has been found. This remains unchanged also in (Co90Fe10)20Ag80 films with Cu80Ag15Au5 underlayer. Using of the underlayer leads to an enhancement of the mean particle size (1.8-2.5 nm) and GMR; however, to a reduction of distances between particles accompanied by the destruction of the <111> texture in the Ag matrix structure. The reason of the GMR effect in the nanogranular films is discussed by means of the obtained results.

  7. Facile synthesis, structure, and properties of Ag2S/Ag heteronanostructure

    NASA Astrophysics Data System (ADS)

    Sadovnikov, S. I.; Gusev, A. I.

    2016-09-01

    Ag2S/Ag heteronanostructure has been produced by a simple one-stage chemical deposition from aqueous solutions of silver nitrate, sodium sulfide, and sodium citrate with the use of monochromatic light irradiation. For simultaneous synthesis of Ag2S and Ag nanoparticles, deposition has been performed from reaction mixtures with reduced sodium sulfide concentration. The size of Ag2S and Ag nanoparticles is 45-50 and 15-20 nm, respectively. It is established that in the contact layer between silver sulfide and silver, nonconducting α-Ag2S acanthite transforms into superionic β-Ag2S argentite under the action of external electric field. The scheme of the operation of a resistive switch based on an Ag2S/Ag heteronanostructure is proposed. The UV-Vis optical absorption spectra of colloidal solutions of Ag2S/Ag heteronanostructures have been studied.

  8. Paleomagnetic Age for the World-class Century Zn-Pb-Ag Deposit, Australia

    NASA Astrophysics Data System (ADS)

    Kawasaki, K.; Symons, D. T.; Dawborn, T.

    2009-05-01

    Paleomagnetic results are reported for the Century Zn-Pb-Ag SEDEX deposit in northwestern Queensland, Australia. The stratiform mineralization occurs in fine parallel lamellae in ˜1595 Ma siderite-rich siltstones and black shales of the upper Lawn Hill Formation in the Proterozoic McNamara Group. Galena from the deposit has given a Pb/Pb model age of ˜1575 Ma. Paleomagnetic analysis of 333 specimens from ore zones (15 sites), and hanging wall (4 sites) and footwall (5 sites) siltstones using mostly thermal and then alternating field step demagnetization, isolates a stable characteristic remanent magnetization (ChRM) for the ore sites only. Step demagnetization, rock magnetic tests and thermomagnetic analyses of ore, Zn and Pb concentrates and tailings show that the main remanence carriers are single- or pseudosingle-domain inclusions of titanomagnetite in sphalerite and gangue, and pyrrhotite in galena with modern goethite and/or hematite from the weathering of siderite. A paleomagnetic fold test using the ore sites is positive, showing that the ore ChRM predates D2 deformation in the ˜1595 to ˜1500 Ma Isan orogeny. The orogeny folded the main-stage mineralization, indicating that the ore retains a primary magnetization. The optimum 80% tilt-corrected unit mean ChRM direction for the ore gives a Mesoproterozoic paleopole at ˜1560 Ma on the northern Australian apparent polar wander path. Thus this result both constrains the timing of mineralization and provides an upper age limit for D2 deformation in the orogeny.

  9. 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.

  10. Gilbert damping in magnetic layered systems

    NASA Astrophysics Data System (ADS)

    Barati, E.; Cinal, M.; Edwards, D. M.; Umerski, A.

    2014-07-01

    The Gilbert damping constant present in the phenomenological Landau-Lifshitz-Gilbert equation describing the dynamics of magnetization is calculated for ferromagnetic metallic films as well as Co/nonmagnet (NM) bilayers. The calculations are done within a realistic nine-orbital tight-binding model including spin-orbit coupling. The convergence of the damping constant expressed as a sum over the Brillouin zone is remarkably improved by introducing finite temperature into the electronic occupation factors and subsequent summation over the Matsubara frequencies. We investigate how the Gilbert damping constant depends on the ferromagnetic film thickness as well as on the thickness of the nonmagnetic cap in Co/NM bilayers (NM=Cu, Pd, Ag, Pt, and Au). The obtained theoretical dependence of the damping constant on the electron-scattering rate, describing the average lifetime of electronic states, varies substantially with the ferromagnetic film thickness and it differs significantly from the dependence for bulk ferromagnetic metals. The presence of nonmagnetic caps is found to largely enhance the magnetic damping in Co/NM bilayers in accordance with experimental data. Unlike Cu, Ag, and Au a particularly strong enhancement is obtained for Pd and Pt caps. This is attributed to the combined effect of the large spin-orbit couplings of Pd and Pt and the simultaneous presence of d states at the Fermi level in these two metals. The calculated Gilbert damping constant also shows an oscillatory dependence on the thicknesses of both ferromagnetic and nonmagnetic parts of the investigated systems which is attributed to quantum-well states. Finally, the expression for contributions to the damping constant from individual atomic layers is derived. The obtained distribution of layer contributions in Co/Pt and Co/Pd bilayers proves that the enhanced damping which affects the dynamics of the magnetization in the Co film originates mainly from a region within the nonmagnetic part of the

  11. Polyhedral AgBr microcrystals with an increased percentage of exposed {111} facets as a highly efficient visible-light photocatalyst.

    PubMed

    Wang, Hua; Lang, Xiufeng; Gao, Jian; Liu, Wei; Wu, Di; Wu, Yongmin; Guo, Lin; Li, Jinghong

    2012-04-10

    Synthesis of inorganic single crystals with exposed high-reactivity facets is a desirable target in the catalytic chemistry field. Polyhedral AgBr microcrystals with an increased percentage of exposed high-reactivity {111} facets have been successfully prepared for the first time, and the photocatalytic performance of these microcrystals when used as an AgBr/Ag plasmonic photocatalyst was investigated. The results indicate that the as-prepared sample has high photocatalytic activity and, under the same measurement conditions, the photodegradation rate of methyl orange dye over these microcrystals is at least four times faster than with other shapes of AgBr/Ag microstructure, as well as 20 times faster than with the highly efficient Ag(3)PO(4) photocatalyst. DFT calculations suggest that the AgBr (111) surface is mainly composed of unsaturated Ag atoms and has a relatively high surface energy, both of which are favorable for enhancing the photocatalytic activity of the AgBr/Ag polyhedron photocatalyst. This work not only provides a highly efficient plasmonic photocatalyst of polyhedral AgBr/Ag microcrystals with an increased percentage of exposed high-reactivity AgBr {111} facets, but also demonstrates that the shape and crystalline quality of the exposed facets have an important influence on the photocatalytic activities.

  12. Exploiting Electric and Magnetic Fields for Underwater Characterization

    DTIC Science & Technology

    2011-03-01

    numerical models in order to quantify the practical limits on standoff excitation for induction coil (magnetic dipole) and electrode (electric dipole...commercially available electric (Ag/AgCl electrodes) and magnetic (wideband induction coil B-field sensors) receivers formed an initial testbed for...improved performance using an electric field source rather than marinized versions of terrestrial induction coil sources (e.g., EM-61S).  Interaction with

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

    PubMed

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Kim, Taekyeong

    2015-09-01

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

  15. Tune control in the Fermilab Main Injector

    SciTech Connect

    G. Wu et al.

    1999-04-16

    We describe methods used to measure and control tunes in the Fermilab Main Injector (FMI). Emphasis is given to software implementation of the operator interface, to the front-end embedded computer system, and handling of hysteresis of main dipole and quadrupole magnets. Techniques are developed to permit control of tune of the Main Injector through several acceleration cycles: from 8.9 GeV/c to 120 GeV/c, from 8.9 GeV/c to 150 GeV/c, and from 150 GeV/c to 8.9 GeV/c. Systems which automate the complex interactions between tune measurement and the variety of ramping options are described. Some results of tune measurements and their comparison with the design model are presented.

  16. Optics Simulations for the NLC Main Linac

    SciTech Connect

    Woodley, Mark D

    2001-06-15

    Focusing in the NLC main linac will be provided mainly by hybrid permanent magnet quadrupoles which have limited variability in strength. When the energy profile of the linac changes, due to normal cycling of rf sources, mismatches in the beam optics can be generated if the quadrupole strengths are not rescaled to the new energy profile. These mismatches can lead to emittance dilution. In addition, betatron phase advance changes caused by the mismatch can adversely affect the beam trajectory, leading to emittance dilution from dispersion and wakefields. This paper describes the results of simulations of these processes, undertaken in an attempt to determine whether or not rescaling of the quadrupoles will be necessary in the NLC main linac.

  17. Synthesis, structure, and electronic structure of CsAgGa{sub 2}Se{sub 4}

    SciTech Connect

    Mei Dajiang; Yin Wenlong; Feng Kai; Bai Lei; Lin Zheshuai; Yao Jiyong; Wu Yicheng

    2012-02-15

    The new metal chalcogenide CsAgGa{sub 2}Se{sub 4} has been synthesized by means of the reactive flux method. It crystallizes in the space group P2{sub 1}/c of the monoclinic system with cell dimensions of a=11.225(2) A, b=7.9443(16) A, c=21.303(4) A, {beta}=103.10(3), V=1850.3(6), and Z=8. The structure contains two-dimensional {sub {infinity}}{sup 2}[AgGa{sub 2}Se{sub 4}]{sup -} layers separated by Cs{sup +} cations. The {sub {infinity}}{sup 2}[AgGa{sub 2}Se{sub 4}]{sup -} superlayer possesses a novel chain-sublayer-chain structure: a {sub {infinity}}{sup 2}[Ag{sub 2}GaSe{sub 6}]{sup 7-} sublayer, composed of {sub {infinity}}{sup 1}[AgGaSe{sub 4}]{sup 4-} chains that are further connected by Ag{sup +} ions, is sandwiched by parallel {sub {infinity}}{sup 1}[Ga{sub 3}Se{sub 8}]{sup 7-} chains to generate the {sub {infinity}}{sup 2}[AgGa{sub 2}Se{sub 4}]{sup -} superlayer. From a band structure calculation, the orbitals of all atoms have contributions to the bottoms of conduction bands, but the band gap is mainly determined by the 4s, 4p orbitals of Ga and Se. - Graphical Abstract: CsAgGa{sub 2}Se{sub 4} contains two-dimensional {sub {infinity}}{sup 2}[AgGa{sub 2}Se{sub 4}]{sup -} layers with a novel chain-sublayer-chain structure. Highlights: Black-Right-Pointing-Pointer New chalcogenide CsAgGa{sub 2}Se{sub 4} has been synthesized. Black-Right-Pointing-Pointer It possesses a new structure type with {sub {infinity}}{sup 2}[AgGa{sub 2}Se{sub 4}]{sup -} layers separated by Cs{sup +} cations. Black-Right-Pointing-Pointer {sub {infinity}}{sup 2}[AgGa{sub 2}Se{sub 4}]{sup -} consists of a {sub {infinity}}{sup 2}[Ag{sub 2}GaSe{sub 6}]{sup 7-} sublayer sandwiched by {sub {infinity}}{sup 1}[Ga{sub 3}Se{sub 8}]{sup 7-} chains. Black-Right-Pointing-Pointer Band gap of CsAgGa{sub 2}Se{sub 4} is mainly determined by the 4s, 4p orbitals of Ga and Se.

  18. Preparation and photocatalytic properties of AgI–SnO{sub 2} nano-composites

    SciTech Connect

    Wen, Biao; Wang, Xiao-Hui; Lu, Juan; Cao, Jia-Lei; Wang, Zuo-Shan

    2013-05-15

    Highlights: ► AgI–SnO{sub 2} nano-composites have been successfully synthesized. ► As-prepared AgI–SnO{sub 2} nano-composites own the excellent visible light photocatalytic activity. ► As-prepared AgI–SnO{sub 2} nano-composites own the excellent stability. - Abstract: AgI doped SnO{sub 2} nano-composites were prepared by the chemical coprecipitation method and were characterized by the X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Results showed that main of the I{sup −} ions remained in the AgI lattice which is highly dispersed in the system. The photo-catalytic experiments performed under visible light irradiation using methylene blue as the pollutant revealed that not only the photo-catalytic activity but also the stability of SnO{sub 2} based photocatalyst could be improved by introduction of an appropriate amount of AgI, and the result was further supported by the UV–Vis diffuse reflection spectra and the electron spin-resonance spectra. Among all of the samples, AgI–SnO{sub 2} nano-composite with 2At% AgI exhibited the best catalytic efficiency and stability.

  19. Optimization of the AGS superconducting helical partial snake strength.

    SciTech Connect

    Lin,F.; Huang, H.; Luccio, A.U.; Roser, T.

    2008-06-23

    Two helical partial snakes, one super-conducting (a.k.a cold snake) and one normal conducting (a.k.a warm snake), have preserved the polarization of proton beam up to 65% in the Brookhaven Alternating Gradient Synchrotron (AGS) at the extraction energy from 85% at injection. In order to overcome spin resonances, stronger partial snakes would be required. However, the stronger the partial snake, the more the stable spin direction tilted producing a stronger horizontal intrinsic resonance. The balance between increasing the spin tune gap generated by the snakes and reducing the tilted stable spin direction has to be considered to maintain the polarization. Because the magnetic field of the warm snake has to be a constant, only the cold snake with a maximum 3T magnetic field can be varied to find out the optimum snake strength. This paper presents simulation results by spin tracking with different cold snake magnetic fields. Some experimental data are also analyzed.

  20. Preliminary study of AC power feeders for AGS booster

    SciTech Connect

    Meth, M.

    1992-07-17

    It has been proposed that the AGS Heavy Ion/Proton Booster be excited directly from the electric power distribution system without intervening an energy storage buffer such as an MG set or a magnetic energy buffer. The average power requirement of the AGS Booster is less than many single-loads presently housed on the lab site. However, the power swing will be the largest single pulsating load on the lab site. The large power swings will impact on the power grid producing utility-line disturbances such as voltage fluctuations and harmonic generation. Thus, it is necessary to carefully evaluate the quality of the electric power system resulting from the interconnection, such that the utility system is not degraded either on the lab site or at LILCO's substation.

  1. Preliminary study of AC power feeders for AGS booster

    SciTech Connect

    Meth, M.

    1992-07-17

    It has been proposed that the AGS Heavy Ion/Proton Booster be excited directly from the electric power distribution system without intervening an energy storage buffer such as an MG set or a magnetic energy buffer. The average power requirement of the AGS Booster is less than many single-loads presently housed on the lab site. However, the power swing will be the largest single pulsating load on the lab site. The large power swings will impact on the power grid producing utility-line disturbances such as voltage fluctuations and harmonic generation. Thus, it is necessary to carefully evaluate the quality of the electric power system resulting from the interconnection, such that the utility system is not degraded either on the lab site or at LILCO`s substation.

  2. AG Draconis - a symbiotic mystery

    NASA Astrophysics Data System (ADS)

    Galis, R.; Hric, L.; Smelcer, L.

    2015-02-01

    Symbiotic system AG Draconis regularly undergoes quiescent and active stages which consist of the series of individual outbursts. The period analysis of new and historical photometric data, as well as radial velocities, confirmed the presence of the two periods. The longer one (~550 d) is related to the orbital motion and the shorter one (~355 d) could be due to pulsation of the cool component of AG Dra. In addition, the active stages change distinctively, but the outbursts are repeated with periods from 359 - 375 d.

  3. Studies of induced radioactivity at the AGS

    SciTech Connect

    Brown, K.A.; Tanaka, M.

    1987-01-01

    With the goals of higher proton intensities, along with the many modes the AGS now runs and those being commissioned to run, we have begun detailed studies of the beam induced radioactivity in the AGS.

  4. 22. View showing main anchor arm, as viewed from main ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. View showing main anchor arm, as viewed from main cantilever arm looking south. Note upper chord eyebar arrangement. - Williamstown-Marietta Bridge, Spanning Ohio River between Williamstown & Marietta, Williamstown, Wood County, WV

  5. 6. MAIN AND SOUTH BAYS. DETAIL OF TOP OF MAIN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. MAIN AND SOUTH BAYS. DETAIL OF TOP OF MAIN BAY COLUMN, GIRDER FOR ELECTRIC OVERHEAD TRAVEL CRANE, AND ROOF GIRDERS - Oldman Boiler Works, Fabricating Shop, 32 Illinois Street, Buffalo, Erie County, NY

  6. Chemical patterning of Ag(111): Spatially confined oxide formation induced by electron beam irradiation

    SciTech Connect

    Guenther, S.; Reichelt, R.; Wintterlin, J.; Barinov, A.; Mentes, T. O.; Nino, M. A.; Locatelli, A.

    2008-12-08

    Low energy electron irradiation of a Ag(111) surface during NO{sub 2} adsorption at 300 K induces formation of Ag oxide. Using a spatially confined electron beam, small Ag{sub 2}O spots could be grown with a sharp, {approx}100 nm wide, boundary to the nonirradiated metallic surface. Since the structure size will mainly depend on the sharpness of the irradiating electron beam, this process has the potential of a single step nanostructuring process. Temperature treatment offers an easy way to manipulate the boundary between oxide and metallic silver by steering a chemical front.

  7. Ag nanotubes and Ag/AgCl electrodes in nanoporous membranes.

    PubMed

    Davenport, Matthew; Healy, Ken; Siwy, Zuzanna S

    2011-04-15

    Miniaturization of the entire experimental setup is a key requirement for widespread application of nanodevices. For nanopore biosensing, integrating electrodes onto the nanopore membrane and controlling the pore length is important for reducing the complexity and improving the sensitivity of the system. Here we present a method to achieve these goals, which relies on electroless plating to produce Ag nanotubes in track-etched polymer nanopore templates. By plating from one side only, we create a conductive nanotube that does not span the full length of the pore, and thus can act as a nanoelectrode located inside the nanopore. To give optimal electrochemical behavior for sensing, we coat the Ag nanotube with a layer of AgCl. We characterize the behavior of this nanoelectrode by measuring its current-voltage response and find that, in most cases, the response is asymmetric. The plated nanopores have initial diameters between 100 and 300 nm, thus a range suitable for detection of viruses.

  8. AGS experiments: 1990, 1991, 1992. Ninth edition

    SciTech Connect

    Depken, J.C.

    1993-04-01

    This report contains a description of the following: AGS Experimental Area - High Energy Physics FY 1993 and Heavy Ion Physics FY 1993; Table of Beam Parameters and Fluxes; Experiment Schedule ``as run``; Proposed 1993 Schedule; A listing of experiments by number; Two-page summaries of each experiment begin here, also ordered by number; Publications of AGS Experiments; and List of AGS Experimenters.

  9. A deeper insight into (Lu,Y)AG:Pr scintillator crystals

    NASA Astrophysics Data System (ADS)

    Drozdowski, W.; Wojtowicz, A. J.; Brylew, K.; Łachmański, W.; Talik, E.; Szubka, M.; Kusz, J.; Guzik, A.; Balin, K.; Kisielewski, J.; Świrkowicz, M.; Pajączkowska, A.

    2017-02-01

    Interior of Czochralski-grown (Lu,Y)AG:Pr crystals has been examined by means of several techniques, such as X-Ray Photoelectron Spectroscopy, X-Ray Diffraction, Time-of-Flight Secondary Ion Mass Spectrometry, and magnetic susceptibility measurements. Additionally, their luminescence has been monitored at various combinations of a double-beam (X-ray/IR) excitation.

  10. Improved Workability of the Nanocomposited AgSnO2 Contact Material and Its Microstructure Control During the Arcing Process

    NASA Astrophysics Data System (ADS)

    Wang, Yaping; Li, Haiyan

    2017-02-01

    There are two major weaknesses for the AgSnO2 contacts used in the low voltage switch devices. One is poor workability, which causes the AgSnO2 materials to hardly deform into the required shape. Another is the increased contact resistance after arcing, which, in turn, causes an unfavorable temperature rise in the switches. In this article, the nanocomposited AgSnO2 materials were developed to overcome the weaknesses. The nanosized SnO2 powders with or without CuO additive were prepared by the chemical precipitation method. The SnO2 powders and Ag powders were high energy milled together to obtain AgSnO2 composite powders, which were then sintered, hot pressed and extruded. It was found that the SnO2 particles mainly distribute in the interior of Ag grains with Ag film on the grain boundary. The hardness of AgSnO2 composites and the wetting angle of Ag melt on SnO2 particles decreased with the addition of a small amount of CuO. By the combining effect of Ag film on grain boundary and the addition of CuO, the elongation and workability of the AgSnO2 materials improved. The experiments of rapid solidification revealed that more SnO2 particles with CuO addition were engulfed in the Ag matrix than those without CuO, which inhibited the redistribution of SnO2 particles on the contact surface during the arcing process. The industrial type test in the 45A contactor suggested that the nanocomposited AgSnO2 materials are suitable to be used as contacts in low voltage switches.

  11. Activation properties of Ag+-ion conduction in bulk amorphous AgI: estimation from extrapolation of the AgI composition dependence in AgI Ag2O P2O5 glasses

    NASA Astrophysics Data System (ADS)

    Hanaya, M.; Hatate, A.; Oguni, M.

    2003-06-01

    AgI-based fast-ion conducting glasses with very high AgI compositions from the (AgI)x(AgPO3)1-x, (AgI)x(Ag2PO3.5)1-x, and (AgI)x(Ag3PO4)1-x systems were prepared successfully by using a rapid-press quenching and a twin-roller quenching method. The ac dielectric measurements showed common relaxation properties of Ag+-ion conduction in the glasses independently of the species of the glass network formers of AgPO3, Ag2PO3.5, and Ag3PO4, and the activation energies, Δɛa, for Ag+-ion conduction were observed to converge upon the same magnitude of ~26 kJ mol-1 at the AgI composition limit of x = 1. This indicates the formation of amorphous AgI regions in the glasses, and the value of Δɛa = 26 +/- 1 kJ mol-1 estimated at x = 1 was concluded to correspond to that for bulk amorphous AgI which has never been obtained experimentally.

  12. AGS 20th anniversary celebration

    SciTech Connect

    Baggett, N.V.

    1980-05-22

    On May 22, 1980, a symposium was held at Brookhaven to celebrate the 20th birthday of the AGS, to recall its beginnings, and to review major discoveries that have been made with its beams. The talks at the symposium are recorded in this volume.

  13. AGS experiments, 1988, 1989, 1990

    SciTech Connect

    Depken, J.C.

    1991-04-01

    This report contains: experimental areas layout; table of beam parameters and fluxes; experiment schedule as run''; experiment long range schedule; a listing of experiments by number; two-page summaries of each experiment begin here, also ordered by number; publications of AGS experiments; and list of experimenters.

  14. AGS experiments: 1985, 1986, 1987

    SciTech Connect

    Depken, J.C.

    1987-01-01

    This report contains: Experimental areas layout, table of beam parameters and fluxes, experiment schedule ''as run,'' experiment long range schedule, a listing of experiments by number, two-page summaries of each experiment, also ordered by number, and publications of AGS experiments, 1982-1987.

  15. Crystal structure and properties of tetragonal EuAg{sub 4}In{sub 8} grown by metal flux technique

    SciTech Connect

    Subbarao, Udumula; Sarkar, Sumanta; Peter, Sebastian C.

    2015-03-15

    The compound EuAg{sub 4}In{sub 8} has been obtained as single crystals in high yield from reactions run in liquid indium. X-ray diffraction on single crystals suggests that EuAg{sub 4}In{sub 8} crystallizes in the CeMn{sub 4}Al{sub 8} structure type, tetragonal space group I4/mmm with lattice constants a=b=9.7937(2) Å and c=5.7492(2) Å. Crystal structure of EuAg{sub 4}In{sub 8} is composed of pseudo Frank–Kasper cages occupied by one europium atom in each ring, which are shared through the corner along the ab plane resulting in a three dimensional network. The magnetic susceptibility of EuAg{sub 4}In{sub 8} was measured in the temperature range 2–300 K, which obeyed Curie–Weiss law above 50 K. Magnetic moment value calculated from the fitting indicates the presence of divalent europium, which was confirmed by X-ray absorption near edge spectroscopy. Electrical resistivity measurements suggest that EuAg{sub 4}In{sub 8} is metallic in nature with a probable Fermi liquid behavior at low temperature. - Graphical abstract: The tetragonal EuAg{sub 4}In{sub 8} has been grown as single crystals from reactions run in liquid indium. Magnetic and XANES measurements suggest divalent nature of Eu and resistivity measurements suggest metallic nature. - Highlights: • EuAg{sub 4}In{sub 8} phase having tetragonal phase is grown by metal flux technique. • Magnetic and XANES measurements exhibit divalent nature of Eu in EuAg{sub 4}In{sub 8}. • Resistivity measurement suggests metallic nature and probable Fermi liquid behavior.

  16. Bioaccumulation of Zn and Ag Nanoparticles in the Earthworms (Eisenia fetida)

    NASA Astrophysics Data System (ADS)

    Ha, Lee Seung; Sung-Dae, Kim; Yi, Yang Song; Byeong-Gweon, Lee

    2014-05-01

    Many studies are carried out to evaluate environmental effects of engineered nanoparticles (ENPs). Most of the previous studies primarily focused on the effects of nanoparticles into the aquatic environment and human. Model studies predict that ENPs released into environment would transferred primarily to the soil of the terrestrial environment. Despite this prediction, biogeochemical behavior of ENPs in soil environment as well as bioavailability of ENPs to soil-dwelling organisms such as earthworm, springtail, isopod and nematodes are poorly understood. The main goal of this study was to compare the bioaccumulation factor (BAFs) and subcellular partitioning of nanoparticles in the soil-dwelling earthworm (Eisenia fetida) from ENP (ZnO and Ag nanoparticles) or ionic metal (Zn2+, Ag+) contaminated soil. And the sequential extraction was also used to determine the mobility of metals in soil which could be used as to predict bioavailability and compare that with bioaccumulation factor. The radiotracer method was employed to trace the transfer of ENPs and ionic metal among different environmental media and animals. Radiolabeled 65ZnO, 110mAgNPs coated with PVP or citrate were synthesized in the laboratory and their chemical and biological behavior was compared to ionic 65Zn and 110mAg. The BAFs of Zn and Ag in the earthworms were determined after animals exposed to the contaminated soils. After the 7 days of elimination phase, subcellular partitioning of metals were also obtained. BAF for ZnO(0.06) was 31 times lower than that for Zn ion (1.86), suggesting that ZnO was less bioavailable than its ionic form from contaminated soil. On the other hands, BAFs for AgNPs coated with PVP (0.12) or with citrate (0.11) were comparable to those for Ag ion (0.17), indicating that Ag from contaminated soil was bioavailable in a similar rate regardless of chemical forms. The subcellular partitioning results showed that bioaccumulated Zn from Zn ion and ZnO contaminated soil were

  17. The Main Achievements of the Laa Project

    NASA Astrophysics Data System (ADS)

    Zichichi, A.

    The following sections are included: * INTRODUCTION * General philosophy of the LAA Project * The basic data * The Physics at the new generation of Hadron Colliders * Present structure of the LAA project * Participants * The Main achievements of the LAA Project * STATUS OF THE PROJECT * High Precision Tracking * Gaseous detectors * Scintillating fibres * Microstrip GaAs * CALORIMETRY * High precision electro-magnetic * Compact EM+Hadronic * "Perfect" Calorimetry * LARGE AREA DEVICES * Construction * Alignment * LEADING PARTICLE DETECTION * Radiation-hard technologies * DATA ACQUISITION AND ANALYSIS * SUPER COMPUTERS AND MONTE CARLO SIMULATIONS * CONCLUSIONS * References

  18. Antibacterial activity and reusability of CNT-Ag and GO-Ag nanocomposites

    NASA Astrophysics Data System (ADS)

    Kim, Ji Dang; Yun, Hyosuk; Kim, Gwui Cheol; Lee, Chul Won; Choi, Hyun Chul

    2013-10-01

    A facile approach to the synthesis of novel CNT-Ag and GO-Ag antibacterial materials, in which thiol groups are utilized as linkers to secure silver (Ag) nanoparticles to the CNT and GO surfaces without agglomeration, is reported. The resulting CNT-Ag and GO-Ag samples were characterized by performing TEM, XRD, Auger, XPS, and Raman measurements, which revealed that in these antibacterial materials size-similar and quasi-spherical Ag nanoparticles are anchored to the CNT and GO surfaces. The Ag nanoparticles in CNT-Ag and GO-Ag have narrow size distributions with average diameters of 2.6 and 3.5 nm respectively. The antibacterial activities of CNT-Ag and GO-Ag against Escherichia coli were assessed with the paper-disk diffusion method and by determining the minimal inhibitory concentrations (MICs). CNT-Ag was found to have higher antibacterial activity than the reference Ag colloid. Moreover, both CNT-Ag and GO-Ag retain more than 50% of their original antibacterial activities after 20 washes with detergent, which indicates their potential as antibacterial materials for laboratory and medical purposes.

  19. Comparative Study of Antimicrobial Activity of AgBr and Ag Nanoparticles (NPs)

    PubMed Central

    Suchomel, Petr; Kvitek, Libor; Panacek, Ales; Prucek, Robert; Hrbac, Jan; Vecerova, Renata; Zboril, Radek

    2015-01-01

    The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60–70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120–130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends – the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains. PMID:25781988

  20. Fermilab Main Injector Beam Position Monitor Upgrade

    NASA Astrophysics Data System (ADS)

    Banerjee, B.; Barker, W.; Bledsoe, S.; Boes, T.; Briegel, C.; Capista, D.; Deuerling, G.; Dysert, R.; Forster, R.; Foulkes, S.; Haynes, W.; Hendricks, B.; Kasza, T.; Kutschke, R.; Marchionni, A.; Olson, M.; Pavlicek, V.; Piccoli, L.; Prieto, P.; Rapisarda, S.; Saewert, A.; Van Bogaert, J.; Votava, M.; Webber, R.; Wendt, M.; Wilcer, N.; Wolbers, S.

    2006-11-01

    An upgrade of the Beam Position Monitor (BPM) signal processing and data acquisition system for the Fermilab Main Injector is described. The Main Injector is a fast cycling synchrotron that accelerates protons or antiprotons from 8 to 150 GeV, Each Main Injector cycle can have a totally different magnet ramp, RF frequency configuration, beam bunch structure, and injection/extraction pattern from the previous cycle. The new BPM system provides the capabilities and flexibility required by the dynamic and complex machine operations. The system offers measurement capability in the 2.5 MHz and 53 MHz channels to detect the range of bunch structures for protons and antiprotons in both wideband (turn-by-turn) and narrowband (closed-orbit) modes. The new BPM read-out system is based on the digital receiver concept and is highly configurable, allowing the signal processing of nearly all Main Injector beam conditions, including the detection of individual batches. An overview of the BPM system in the Main Injector operating environment, some technology details and first beam measurements are presented.

  1. Highly efficient and porous TiO2-coated Ag@Fe3O4@C-Au microspheres for degradation of organic pollutants

    NASA Astrophysics Data System (ADS)

    Shen, Mao; Chen, Suqing; Jia, Wenping; Fan, Guodong; Jin, Yanxian; Liang, Huading

    2016-12-01

    In this paper, we reported a novel hierarchical porous Ag@Fe3O4@C-Au@TiO2 core@shell microspheres with a highly photocatalytic activity and magnetically separable properties. The synthesis method is included of a Fe3O4 magnetic embedded Ag core (Ag@Fe3O4), an interlayer of carbon modified by PEI to form sufficient amounts of amine functional groups (Ag@Fe3O4@C-PEI), the grafting of Au nanoparticles on the surface of Ag@Fe3O4@C-PEI (Ag@Fe3O4@C-Au), and an ordered porous TiO2 structured shell. As an example of the applications, the photocatalytic activities of the samples were investigated by the reduction of Rhodamine B (RhB) under visible-light irradiation. The results show that the porous Ag@Fe3O4@C-Au@TiO2 core@shell microspheres display higher adsorption and photocatalytic activities compared to the pure porous TiO2 and Ag@Fe3O4@C@TiO2 microspheres, which are attributed to the local surface plasmon resonance (LSPR) by the Ag and Au nanoparticles and the high specific surface area.

  2. Characterization of spark plasma sintered Ag nanopowders.

    PubMed

    Fu, Y Q; Shearwood, C; Xu, B; Yu, L G; Khor, K A

    2010-03-19

    The low temperature sintering behaviour of nanocrystalline Ag powder (with an average size of 70 nm) was characterized. Using spark plasma sintering (SPS), the Ag nanopowders can be successfully sintered at low pressure for only 5 min without external heating, and the sintering density increases and porosity decreases significantly with increase in the sintering temperature. Nanoindentation has been used to characterize the SPS sintered Ag samples. The mechanisms of the low sintering temperature behaviour of the nano-Ag powder and the nanoscale mechanical performance have been discussed. Compression tests were also used to characterize the mechanical properties of the sintered Ag sample with a maximum strain up to 15%.

  3. Magnetic particle-scanning for ultrasensitive immunodetection on-chip.

    PubMed

    Cornaglia, Matteo; Trouillon, Raphaël; Tekin, H Cumhur; Lehnert, Thomas; Gijs, Martin A M

    2014-08-19

    We describe the concept of magnetic particle-scanning for on-chip detection of biomolecules: a magnetic particle, carrying a low number of antigens (Ag's) (down to a single molecule), is transported by hydrodynamic forces and is subjected to successive stochastic reorientations in an engineered magnetic energy landscape. The latter consists of a pattern of substrate-bound small magnetic particles that are functionalized with antibodies (Ab's). Subsequationuent counting of the captured Ag-carrying particles provides the detection signal. The magnetic particle-scanning principle is investigated in a custom-built magneto-microfluidic chip and theoretically described by a random walk-based model, in which the trajectory of the contact point between an Ag-carrying particle and the small magnetic particle pattern is described by stochastic moves over the surface of the mobile particle, until this point coincides with the position of an Ag, resulting in the binding of the particle. This model explains the particular behavior of previously reported experimental dose-response curves obtained for two different ligand-receptor systems (biotin/streptavidin and TNF-α) over a wide range of concentrations. Our model shows that magnetic particle-scanning results in a very high probability of immunocomplex formation for very low Ag concentrations, leading to an extremely low limit of detection, down to the single molecule-per-particle level. When compared to other types of magnetic particle-based surface coverage assays, our strategy was found to offer a wider dynamic range (>8 orders of magnitude), as the system does not saturate for concentrations as high as 10(11) Ag molecules in a 5 μL drop. Furthermore, by emphasizing the importance of maximizing the encounter probability between the Ag and the Ab to improve sensitivity, our model also contributes to explaining the behavior of other particle-based heterogeneous immunoassays.

  4. Synergistic effect of interfacial lattice Ag(+) and Ag(0) clusters in enhancing the photocatalytic performance of TiO2.

    PubMed

    Xu, Liming; Zhang, Dandan; Ming, Lufei; Jiao, Yanchao; Chen, Feng

    2014-09-28

    An interfacial lattice Ag(+) doped on TiO2 (Ag(+)/TiO2) was prepared by eluting Ag(0) clusters from a hydrothermally prepared Ag(0)/Ag(+)/TiO2 composite. An Ag(+)/TiO2@Ag(0) composite photocatalyst was subsequently obtained via a secondary Ag(0) clusters loading process to the Ag(+)/TiO2. The photocatalytic activity of Ag(+)/TiO2@Ag(0) was greatly improved compared to Ag(0)/Ag(+)/TiO2 and Ag(+)/TiO2. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) testing verified that Ag(+) ions occur as an interfacial lattice Ag(+) species in the composites. The enhancement effect of the interfacial lattice Ag(+) species is exhibited by the newly-formed Ag(+)/TiO2@Ag(0) as the interfacial lattice Ag(+) is fully exposed but not overlapped with the re-loaded Ag(0) clusters. The interfacial lattice Ag(+) ions and Ag(0) clusters are both responsible for the photocatalytic performance improvement of the catalyst, in either the photocatalytic degradation of methyl orange or photocurrent measurement.

  5. Main field and recent secular variation.

    USGS Publications Warehouse

    Alldredge, L.R.

    1983-01-01

    As Cain (1979) indicated might happen in the last IUGG quadrennial report, added resources were made available during the past few years and a real impulse was added to the geomagnetic work in the US by the launching of the MAGSAT Satellite. This new effort paid off in terms of new charts, additional long wavelength studies, and external source studies. As before, however, the future funding for new starts in geomagnetism does not look bright at the present time. A single MAGSAT in orbit a little more than seven months did wonders for main field (M.F.) charting, but did little or nothing for secular variation (S.V.) charting. It would take a number of repeated MAGSATS to help the S.V. picture. Meanwhile, the world magnetic observatory net and surface repeat stations remain as the main source of S.V. data. -from Author

  6. Tunability of negative permittivity and permeability of Ag/Zr0.9Ni0.1Oy nanocomposites with morphology

    NASA Astrophysics Data System (ADS)

    Gholipur, Reza; Bahari, Ali

    2017-03-01

    In this work, the effect of doping by Ag and stirring time on the structural, dielectrical and magnetical properties of Ag/Zr0.9Ni0.1Oy nanocomposite is considered. For all samples, the transmission electron microscopy (TEM) analyses show that doped Ag nanoparticles are dispersed randomly in the host dielectric. The permittivity and permeability behaviors of samples were investigated. Also, by changing the size of Ag, variation of permittivity and permeability changes are introduced. It was found that samples with 45, 47 and 50 wt% Ag exhibit the double negative (DNG) properties. Simultaneous negative permittivity and negative permeability were tunable in the Ag/Zr0.9Ni0.1Oy nanocomposites. We believe that the this work will be useful to all those interested in preparation of random nanocomposite DNG metamaterial.

  7. Magnetostriction and ferroelectric state in AgCrS₂.

    PubMed

    Streltsov, Sergey V; Poteryaev, Alexander I; Rubtsov, Alexey N

    2015-04-29

    The band structure calculations in the GGA+U approximation show the presence of additional lattice distortions in the magnetically ordered phase of AgCrS2. The magnetostriction leads to the formation of long and short Cr-Cr bonds in the case when the respective Cr ions have the same or opposite spin projections. These changes in the Cr lattice are accompanied by distortions of the CrS6 octahedra, which in turn lead to the development of spontaneous electric polarization.

  8. Synthesis of Ag-ZnO with multiple rods (multipods) morphology and its application in the simultaneous photo-catalytic degradation of methyl orange and methylene blue.

    PubMed

    Arab Chamjangali, M; Bagherian, G; Javid, A; Boroumand, S; Farzaneh, N

    2015-11-05

    In this study, the photo-decolorization of a mixture of methylene blue (MB) and methyl orange (MO) was investigated using Ag-ZnO multipods. The photo-catalyst used, ZnO multipods, was successfully synthesized. The surface of ZnO microstructure was modified by deposition of different amounts of Ag nanoparticles (Ag NPs) using the photo-reduction method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis and atomic absorption spectroscopy. The photo-catalytic efficiency of Ag-ZnO is mainly controlled by the amount of Ag NPs deposited on the ZnO surface. The results obtained suggest that Ag-ZnO containing 6.5% Ag NPs, has the highest photo-catalytic performance in the simultaneous photo-degradation of dyes at a shorter time.

  9. 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.

  10. Enhancing the ag precipitation by surface mechanical attrition treatment on Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Liu, Jiabin; Zhang, Lehao; Liu, Jingjing; Huang, Liuyi; Gu, Hao; Fang, Youtong; Meng, Liang; Zhang, Jian

    2016-09-01

    The influence of surface mechanical attrition treatment (SMAT) on Ag precipitation in Cu-Ag alloys was investigated. Cu-6 wt% Ag was melt, cold rolled and solution treated to be Cu-Ag solid solution, which was either aged at 250 and 350 °C for 24 h directly or SMAT-ed before aging. Ag precipitates were hard be found in the directly aged Cu-Ag sample while they were observed clearly in the SMAT-ed counterpart at 250 °C. The Ag precipitates formed in the surface layer by SMAT are much coarser than those in the un-SMAT-ed sample. It is obvious that the precipitating behavior of Ag was promoted significantly by SMAT approach. A large number of defects were generated by SMAT and they were acting as fast atomic diffusion channels that facilitated the atomic diffusion of Ag.

  11. Flexible IZO/Ag/IZO/Ag multilayer electrode grown on a polyethylene terephthalate substrate using roll-to-roll sputtering

    PubMed Central

    2012-01-01

    We investigated the optical, electrical, structural, and surface properties of roll-to-roll [R2R] sputter-grown flexible IZO/Ag/IZO/Ag [IAIA] multilayer films on polyethylene terephthalate substrates as a function of the top indium zinc oxide [IZO] thickness. It was found that the optical transmittance of the IAIA multilayer was significantly influenced by the top IZO layer thickness, which was grown on identical AIA multilayers. However, the sheet resistance of the IAIA multilayer was maintained between the range 5.01 to 5.1 Ω/square regardless of the top IZO thickness because the sheet resistance of the IAIA multilayer was mainly dependent on the thickness of the Ag layers. Notably, the optimized IAIA multilayer had a constant resistance change (ΔR/R0) under repeated outer bending tests with a radius of 10 mm. The mechanical integrity of the R2R-sputtered IAIA multilayer indicated that hybridization of an IZO and Ag metal layer is a promising flexible electrode scheme for the next-generation flexible optoelectronics. PMID:22222144

  12. Photosensitization of ZnO by AgBr and Ag2CO3: Nanocomposites with tandem n-n heterojunctions and highly enhanced visible-light photocatalytic activity.

    PubMed

    Pirhashemi, Mahsa; Habibi-Yangjeh, Aziz

    2016-07-15

    Facile ultrasonic-irradiation method was applied for photosensitization of ZnO by combining with AgBr and Ag2CO3 particles through preparation of novel ternary nanocomposites. The prepared samples were characterized by XRD, SEM, TEM, EDX, UV-Vis DRS, FT-IR, BET, and PL techniques. Photocatalytic activity was investigated by degradation of rhodamine B under visible-light irradiation. It was found that photocatalytic activity of the ZnO was greatly enhanced by coupling with AgBr and Ag2CO3 particles, as narrow band gap semiconductors, through formation of tandem n-n heterojunctions. The nanocomposite with 20% of Ag2CO3 displayed the highest photocatalytic activity with the degradation rate constants which are nearly 122, 31, and 25 times higher than those of the ZnO, ZnO/AgBr, and ZnO/Ag2CO3 samples, respectively. Moreover, the trapping experiments confirmed that superoxide ion radicals and holes are the main active species responsible for the degradation reaction. Finally, it was also demonstrated that the ternary ZnO/AgBr/Ag2CO3 (20%) nanocomposite has enhanced activity in degradation of methylene blue and methyl orange. Hence, this work shows a great potential of the ternary photocatalyst for purification of contaminated water from organic pollutants.

  13. Advances In Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    1994-01-01

    NASA technical memorandum reviews state of technology of magnetic bearings, focusing mainly on attractive bearings rather than repulsive, eddy-current, or Lorentz bearings. Attractive bearings offer greater load capacities and preferred for aerospace machinery.

  14. Ring Current Development During Storm Main Phase

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Moore, Thomas E.; Greenspan, Marian E.

    1996-01-01

    The development of the ring current ions in the inner magnetosphere during the main phase of a magnetic storm is studied. The temporal and spatial evolution of the ion phase space densities in a dipole field are calculated using a three dimensional ring current model, considering charge exchange and Coulomb losses along drift paths. The simulation starts with a quiet time distribution. The model is tested by comparing calculated ion fluxes with Active Magnetospheric Particle Tracer Explorers/CCE measurement during the storm main phase on May 2, 1986. Most of the calculated omnidirectional fluxes are in good agreement with the data except on the dayside inner edge (L less than 2.5) of the ring current, where the ion fluxes are underestimated. The model also reproduces the measured pitch angle distributions of ions with energies below 10 keV. At higher energy, an additional diffusion in pitch angle is necessary in order to fit the data. The role of the induced electric field on the ring current dynamics is also examined by simulating a series of substorm activities represented by stretching and collapsing the magnetic field lines. In response to the impulsively changing fields, the calculated ion energy content fluctuates about a mean value that grows steadily with the enhanced quiescent field.

  15. View of the main interior space facing east. The main ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of the main interior space facing east. The main entry is on the left hand side at the rear. The exit to the deck is to the right. - San Luis Yacht Club, Avila Pier, South of Front Street, Avila Beach, San Luis Obispo County, CA

  16. 18. MAIN FLOOR HOLDING TANKS Main floor, looking at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. MAIN FLOOR - HOLDING TANKS Main floor, looking at holding tanks against the west wall, from which sluice gates are seen protruding. Right foreground-wooden holding tanks. Note narrow wooden flumes through which fish were sluiced into holding and brining tanks. - Hovden Cannery, 886 Cannery Row, Monterey, Monterey County, CA

  17. Thermoelectric Properties of CuAgSe doped with Co, Cr

    NASA Astrophysics Data System (ADS)

    Czajka, Peter; Yao, Mengliang; Opeil, Cyril

    Thermoelectric materials represent one way that reliable cooling below the boiling point of nitrogen can be realized. Current materials do not exhibit sufficiently high efficiencies at cryogenic temperatures, but significant progress is being made. One material that has generated significant interest recently is CuAgSe. It has been demonstrated (Ishiwata et al., Nature Mater. 2013) that doping CuAgSe with 10% Ni at the Cu sites increases the material's thermoelectric figure of merit (ZT) at 100 K from 0.02 to 0.10. This is intriguing not just because of the dramatic effect that the Ni doping produces, but also because CuAgSe is a semimetal and semimetals are not usually able to exhibit the kind of asymmetric carrier activation necessary for strong thermoelectric performance. In order to further investigate the unusual nature of thermoelectricity in CuAgSe and its strong dependence on chemical composition, we have synthesized and measured the thermoelectric properties of a series of CuAgSe samples doped with Co and Cr. Temperature-dependent magnetic and thermoelectric transport properties of CuAgSe as a function of Co and Cr doping will be discussed. This work is supported by the Department of Defense, AFOSR, MURI Program Contract # FA9550-10-1-0533 and the Trustees of Boston College.

  18. Composition modulation of Ag2Te nanowires for tunable electrical and thermal properties.

    PubMed

    Yang, Haoran; Bahk, Je-Hyeong; Day, Tristan; Mohammed, Amr M S; Min, Bokki; Snyder, G Jeffrey; Shakouri, Ali; Wu, Yue

    2014-09-10

    In this article, we demonstrated that composition modulation of Ag2Te nanowires can be achieved during the self-templated transformation of Te nanowires into Ag2Te nanowires during solution phase synthesis, which provides a mean to tune the carrier density of the Ag2Te nanowires. Both nearly stoichiometric and Ag-rich nanowires have been synthesized, which give rise to p-type and n-type Ag2Te nanocomposites after hot press, respectively. The electrical and thermal properties of the two kinds of samples have been measured. Theoretical modeling based on the near-equilibrium Boltzmann transport equations has been used to understand the experimental results. We found that ZT of the heavily doped n-type sample reaches 0.55 at 400 K, which is the highest ZT value reported for Ag2Te at the same temperature mainly due to the reduced thermal conductivity by the nanostructures. Theoretical analysis on the carrier transport shows that the power factor is also very well optimized in the doped Ag2Te sample considering the reduced carrier mobility by the nanostructures.

  19. Preparation of Ag/TiO2-zeolite adsorbents, their desulfurization performance, and benzothiophene adsorption isotherms

    NASA Astrophysics Data System (ADS)

    Song, Hua; Yang, Gang; Song, Hua-Lin; Wang, Deng; Wang, Xue-Qin

    2017-02-01

    A series of Ag/TiO2-NaY (TY) composite adsorbents were successfully prepared and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, BET, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) techniques. The effects of TiO2 and Ag contents on the structure and desulfurization performance of NaY zeolite were studied. The results show that anatase phase is the main form of TiO2 in AgTY adsorbent, and the Y-zeolite framework remained unchanged. AgTY with 6 wt % of Ag and 50 wt % of TiO2 exhibited the best desulfurization performance with the effluent volume of 63.2 mL/g at 10 mg/L sulfur breakthrough level (desulfurization rate of 95%). The benzothiophene (BT) removal performance of the various adsorbents follows the order: NaY < TiO2 < TY-50 < AgTY-50-6. The equilibrium data were modeled by Langmuir and Freundlich equations. The Langmuir model can describe well the adsorption isotherms of BT over AgTY.

  20. Oxidative degradation of acid orange 7 using Ag-doped zinc oxide thin films.

    PubMed

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

    2012-12-05

    Ag-doped ZnO thin films with preferred c-axis orientation along (002) have been prepared by spray pyrolysis technique in aqueous medium on to the corning glass substrates. The effect of Ag-doping on to the photoelectrochemical, structural, morphological, optical, luminescence, electrical and thermal properties has been investigated. XRD and Raman study indicates that the films have hexagonal (wurtzite) crystal structure. The effect of Ag loading on the photocatalytic activity of Ag-doped ZnO in the degradation of azo dye is studied and results are compared with pure ZnO. The results show that the rate of degradation of azo dye over Ag-doped ZnO is much higher as compared to pure ZnO. Ag doping in ZnO is highly effective and can significantly enhance the photocatalytic degradation and mineralization of azo dye. The enhancement of photocatalytic activity of Ag-doped ZnO thin films is mainly due to their smaller crystallite size and capability for reducing the electron-hole pair recombination. Kinetic parameters have been investigated in terms of a first order rate equation. The rate constant (-k) for this heterogeneous photocatalysis is evaluated as a function of the initial concentration of original species. Substantial reduction in azo dye is achieved as analyzed from COD and TOC studies.

  1. Blood Clearance, Distribution, Transformation, Excretion, and Toxicity of Near-Infrared Quantum Dots Ag2Se in Mice.

    PubMed

    Tang, Huan; Yang, Sheng-Tao; Yang, Yi-Fan; Ke, Da-Ming; Liu, Jia-Hui; Chen, Xing; Wang, Haifang; Liu, Yuanfang

    2016-07-20

    As a novel fluorescent probe in the second near-infrared window, Ag2Se quantum dots (QDs) exhibit great prospect in in vivo imaging due to their maximal penetration depth and negligible background. However, the in vivo behavior and toxicity of Ag2Se QDs still largely remain unknown, which severely hinders their wide-ranging biomedical applications. Herein, we systematically studied the blood clearance, distribution, transformation, excretion, and toxicity of polyethylene glycol (PEG) coated Ag2Se QDs in mice after intravenous administration with a high dose of 8 μmol/kg body weight. QDs are quickly cleared from the blood with a circulation half-life of 0.4 h. QDs mainly accumulate in liver and spleen and are remarkably transformed into Ag and Se within 1 week. Ag is excreted from the body readily through both feces and urine, whereas Se is excreted hardly. The toxicological evaluations demonstrate that there is no overt acute toxicity of Ag2Se QDs to mice. Moreover, in regard to the in vivo stability problem of Ag2Se QDs, the biotransformation and its related metabolism are intensively discussed, and some promising coating means for Ag2Se QDs to avert transformation are proposed as well. Our work lays a solid foundation for safe applications of Ag2Se QDs in bioimaging in the future.

  2. Preserved entropy and fragile magnetism

    DOE PAGES

    Canfield, Paul C.; Bud’ko, Sergey L.

    2016-07-05

    Here, a large swath of quantum critical and strongly correlated electron systems can be associated with the phenomena of preserved entropy and fragile magnetism. In this overview we present our thoughts and plans for the discovery and development of lanthanide and transition metal based, strongly correlated systems that are revealed by suppressed, fragile magnetism, quantum criticality, or grow out of preserved entropy. We will present and discuss current examples such as YbBiPt, YbAgGe, YbFe2Zn20, PrAg2In, BaFe2As2, CaFe2As2, LaCrSb3 and LaCrGe3 as part of our motivation and to provide illustrative examples.

  3. Preserved entropy and fragile magnetism.

    PubMed

    Canfield, Paul C; Bud'ko, Sergey L

    2016-08-01

    A large swath of quantum critical and strongly correlated electron systems can be associated with the phenomena of preserved entropy and fragile magnetism. In this overview we present our thoughts and plans for the discovery and development of lanthanide and transition metal based, strongly correlated systems that are revealed by suppressed, fragile magnetism, quantum criticality, or grow out of preserved entropy. We will present and discuss current examples such as YbBiPt, YbAgGe, YbFe2Zn20, PrAg2In, BaFe2As2, CaFe2As2, LaCrSb3 and LaCrGe3 as part of our motivation and to provide illustrative examples.

  4. Preserved entropy and fragile magnetism

    SciTech Connect

    Canfield, Paul C.; Bud’ko, Sergey L.

    2016-07-05

    Here, a large swath of quantum critical and strongly correlated electron systems can be associated with the phenomena of preserved entropy and fragile magnetism. In this overview we present our thoughts and plans for the discovery and development of lanthanide and transition metal based, strongly correlated systems that are revealed by suppressed, fragile magnetism, quantum criticality, or grow out of preserved entropy. We will present and discuss current examples such as YbBiPt, YbAgGe, YbFe2Zn20, PrAg2In, BaFe2As2, CaFe2As2, LaCrSb3 and LaCrGe3 as part of our motivation and to provide illustrative examples.

  5. Polarimeters for the AGS polarized-proton beam

    SciTech Connect

    Crabb, D.G.; Bonner, B.; Buchanan, J.

    1983-01-01

    This report describes the three polarimeters which will be used to measure the beam polarization at the AGS polarized beam facility. The beam polarization will be measured before injection into the AGS, during acceleration, and after extraction from the AGS. The 200-MeV polarimeter uses scintillation-counter telescopes to measure the asymmetry in p-carbon inclusive scattering. The internal polarimeter can measure the beam polarization at up to five selected times during acceleration. A continuously spooled nylon filament is swung into the beam at the appropriate time and the asymmetry in pp elastic scattering measured by two scintillation-counter telescopes. This is a relative polarimeter which can be calibrated by the absolute external polarimeter located in the D extracted-beam line. This polarimeter uses scintillation counters in two double-arm magnetic spectrometers to measure clearly the asymmetry in pp elastic scattering from a liquid hydrogen target. The specific features and operation of each polarimeter will be discussed.

  6. Controlled synthesis and photocatalysis of sea urchin-like Fe3O4@TiO2@Ag nanocomposites

    NASA Astrophysics Data System (ADS)

    Zhao, Yilin; Tao, Chengran; Xiao, Gang; Wei, Guipeng; Li, Linghui; Liu, Changxia; Su, Haijia

    2016-02-01

    Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the core and nanofiber TiO2/Fe3O4/Ag nanoheterojunctions as the shell; and Ag nanoparticles with diameter of approximately 4 nm are loaded both on TiO2 nanofibers and inside the cavities of sea urchin-like Fe3O4@TiO2 nanocomposites uniformly. Ag nanoparticles lead to the production of more photogenerated charges in the TiO2/Fe3O4/Ag heterojunction via LSPR absorption, and enhance the band-gap absorption of TiO2, while the Fe3O4 cocatalyst provides the active sites for oxygen reduction by the effective transfer of photogenerated electrons to oxygen. So the photocatalytic performance is improved due to the synergistic effect of TiO2/Fe3O4/Ag nanoheterojunctions. As photocatalysts under UV and visible irradiation, the as-synthesized nanocomposites display enhanced photocatalytic and recycling properties for the degradation of ampicillin. Moreover, they present better broad-spectrum antibiosis under visible irradiation. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, makes this multifunctional nanostructure a promising candidate for antibiosis and remediation in aquatic environmental contamination in the future.Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the

  7. Polymorphism of LiAg

    NASA Astrophysics Data System (ADS)

    Pavlyuk, V. V.; Dmytriv, G. S.; Tarasiuk, I. I.; Chumak, I. V.; Pauly, H.; Ehrenberg, H.

    2010-02-01

    A phase transition from the cubic CsCl-type structure (Pm-3m space group) into a tetragonal UPb-type structure (I4 1/amd) is observed for the LiAg binary compound at ambient conditions. The crystal structure of the tetragonal modification of the LiAg binary compound was solved by direct methods in SHELXS on the base of structure factors which were extracted from a powder diffraction pattern and refined by SHELXL and the Rietveld method ( a = 3.9605(1), c = 8.2825(2) Å, Bragg R-factor = 4.81, Rf-factor = 4.87). Elevated temperatures and/or a small Li-excess versus the equimolar composition favour the cubic structure whereas ambient and lower temperatures and/or a small Li-deficiency stabilize the tetragonal structure. This reconstructive transition is reversible but proceeds slowly.

  8. An efficient visible-light photocatalyst prepared by modifying AgBr particles with a small amount of activated carbon

    SciTech Connect

    Wang, Desong Zhao, Mangmang; Luo, Qingzhi; Yin, Rong; An, Jing; Li, Xueyan

    2016-04-15

    Highlights: • An efficient visible-light photocatalyst was prepared by modifying AgBr particles. • A small amount of activated carbon was used to modify AgBr particles. • The modified AgBr exhibited improved visible-light photocatalytic performances. - Abstract: An efficient visible-light photocatalyst was successfully prepared by modifying AgBr particles with a small amount of activated carbon (AC) via a simple chemical precipitation approach. The AC/AgBr composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis diffuse reflection spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy. The photocatalytic performances of the AC/AgBr composite were investigated by evaluating photodegradation of methyl orange (MO) and phenol under visible light irradiation, and the effects of the AC content in the composite, concentrations of AC/AgBr composite and MO, carrier scavengers on MO photodegradation rate were systematically investigated. The results indicated that the modification of AC can hardly change the crystalline and crystal size of AgBr particles, while significantly improve their specific surface areas, visible-light absorption and separation efficiency of photogenerated electron–hole pairs. Compared with pure AgBr, the AC/AgBr composite exhibited drastically enhanced visible-light photocatalytic activity and stability. The photogenerated electrons and holes, hydroxyl radicals are responsible to the photodegradation of organic pollutants, and the photogenerated holes are the main active species. On the basis of the results and the properties of AC and AgBr, the visible-light photocatalytic mechanism of the AC/AgBr composite was discussed.

  9. 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.

  10. Controlled synthesis and photocatalysis of sea urchin-like Fe3O4@TiO2@Ag nanocomposites.

    PubMed

    Zhao, Yilin; Tao, Chengran; Xiao, Gang; Wei, Guipeng; Li, Linghui; Liu, Changxia; Su, Haijia

    2016-03-07

    Based on the synergistic photocatalytic activities of nano-sized TiO2 and Ag, as well as the magnetic properties of Fe3O4, a sea urchin-like Fe3O4@TiO2@Ag nanocomposite (Fe3O4@TiO2@Ag NCs) is controllably synthesized with tunable cavity size, adjustable shell layer of TiO2 nanofiber, higher structural stability and larger specific surface area. Here, Fe3O4@TiO2@Ag NCs are obtained with Fe3O4 as the core and nanofiber TiO2/Fe3O4/Ag nanoheterojunctions as the shell; and Ag nanoparticles with diameter of approximately 4 nm are loaded both on TiO2 nanofibers and inside the cavities of sea urchin-like Fe3O4@TiO2 nanocomposites uniformly. Ag nanoparticles lead to the production of more photogenerated charges in the TiO2/Fe3O4/Ag heterojunction via LSPR absorption, and enhance the band-gap absorption of TiO2, while the Fe3O4 cocatalyst provides the active sites for oxygen reduction by the effective transfer of photogenerated electrons to oxygen. So the photocatalytic performance is improved due to the synergistic effect of TiO2/Fe3O4/Ag nanoheterojunctions. As photocatalysts under UV and visible irradiation, the as-synthesized nanocomposites display enhanced photocatalytic and recycling properties for the degradation of ampicillin. Moreover, they present better broad-spectrum antibiosis under visible irradiation. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, makes this multifunctional nanostructure a promising candidate for antibiosis and remediation in aquatic environmental contamination in the future.

  11. Capacitive deionization of seawater effected by nano Ag and Ag@C on graphene.

    PubMed

    Cai, P-F; Su, C-J; Chang, W-T; Chang, F-C; Peng, C-Y; Sun, I-W; Wei, Y-L; Jou, C-J; Wang, H Paul

    2014-08-30

    Drinking water shortage has become worse in recent decades. A new capacitive deionization (CDI) method for increasing water supplies through the effective desalination of seawater has been developed. Silver as nano Ag and Ag@C which was prepared by carbonization of the Ag(+)-β-cyclodextrin complex at 573 K for 30 min can add the antimicrobial function into the CDI process. The Ag@C and Ag nanoparticles dispersed on reduced graphene oxide (Ag@C/rGO and nano Ag/rGO) were used as the CDI electrodes. The nano Ag/rGO and Ag@C/rGO electrodes can reduce the charging resistant, and enhance the electrosorption capability. Better CDI efficiencies with the nano Ag/rGO and Ag@C/rGO electrodes can therefore be obtained. When reversed the voltage, the electrodes can be recovered up to 90% within 5 min. This work presents the feasibility for the nano Ag and Ag@C on rGO electrodes applied in CDI process to produce drinking water from seawater or saline water.

  12. Maine: Early Head Start Initiatives

    ERIC Educational Resources Information Center

    Center for Law and Social Policy, Inc. (CLASP), 2012

    2012-01-01

    Maine has two initiatives that build on Early Head Start (EHS). The first initiative, Fund for a Healthy Maine, has since 2001 provided tobacco settlement money to existing Head Start and EHS programs to expand the number of children who receive full-day, full-year services. Local programs have the option of using these funds for EHS, depending on…

  13. Maine Indians: A Brief Summary.

    ERIC Educational Resources Information Center

    1971

    The Indians of Maine, descendants of Algonquian linguistic stock, number approximately 1800 and reside on 3 reservations totalling 22,600 acres of land. Most of the reservation land is forested, with important economic and recreational advantages in terms of timber production and hunting and fishing opportunities. In 1965, Maine became the first…

  14. Maine Agricultural Foods. Project SEED.

    ERIC Educational Resources Information Center

    Beaulieu, Peter; Ossenfort, Pat

    This paper describes an activity-based program that teaches students in grades 4-12 about the importance of Maine agriculture in their lives. Specifically, the goal is to increase student awareness of how the foods they eat are planted, harvested, and processed. The emphasis is on crops grown in Maine such as potatoes, broccoli, peas, blueberries,…

  15. Flakes of artificial graphene in magnetic fields

    NASA Astrophysics Data System (ADS)

    Rasanen, Esa; Aichinger, Michael; Janecek, Stefan

    2014-03-01

    Artificial graphene (AG) is a man-made nanomaterial that can be constructed by arranging molecules on a metal surface or by fabricating a quantum-dot lattice in a semiconductor heterostructure. In both cases, AG resembles graphene in many ways, but it also has additional appealing features such as tunability with respect to the lattice constant, system size and geometry, and edge configuration. Here we solve numerically the electronic states of various hexagonal AG flakes similar to those in Ref.. In particular, we demonstrate the formation of the Dirac point as a function of the lattice size and its response to an external, perpendicular magnetic field. Secondly, we examine the complex behavior of the energy levels as functions of both the system size and magnetic field. Eventually, we find the formation of ``Hofstadter's butterfly''-type patterns in the energy spectrum. Supported by Academy of Finland and EC's FP7 through CRONOS project (no. 280879).

  16. Facile synthesis of S-Ag nanocomposites and Ag2S short nanorods by the interaction of sulfur with AgNO3 in PEG400

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Li; Xie, Xin-Yuan; Liang, Ming; Xie, Shu-Ming; Chen, Jie-Mei; Zheng, Wen-Jie

    2016-06-01

    A facile, eco-friendly and inexpensive method to prepare Ag2S short nanorods and S-Ag nanocomposites using sublimed sulfur, AgNO3, PVP and PEG400 was studied. According to x-ray diffraction and scanning electron microscopy of the Ag2S, the products are highly crystalline and pure Ag2S nanorods with diameters of 70-160 nm and lengths of 200-360 nm. X-ray diffraction of the S-Ag nanocomposites shows that we obtained cubic Ag and S nanoparticles. Transmission electron microscopy shows that the molar ratio of PVP to Ag+ plays an important role in controlling the size and morphology of the S-Ag nanocomposites. When the molar ratio of PVP to Ag+ was 10:1, smaller sizes, better dispersibility and narrower distribution of S-Ag nanocomposites with diameters of 10-40 nm were obtained. The formation mechanism of the S-Ag nanocomposites was studied by designing a series of experiments using ultraviolet-visible measurement, and it was found that S nanoparticles are produced first and act as seed crystals; then Ag+ becomes Ag nanocrystals on the surfaces of the S nanoparticles by the reduction of PVP. PEG400 acts as a catalyzer, accelerating the reaction rate, and protects the S-Ag nanocomposites from reacting to produce Ag2S. The antimicrobial experiments show that the S-Ag nanocomposites have greater antimicrobial activity on Staphylococcus aureus, Aspergillus niger and blue mold than Ag nanoparticles.

  17. Main Propulsion Test Article (MPTA)

    NASA Technical Reports Server (NTRS)

    Snoddy, Cynthia

    2010-01-01

    Scope: The Main Propulsion Test Article integrated the main propulsion subsystem with the clustered Space Shuttle Main Engines, the External Tank and associated GSE. The test program consisted of cryogenic tanking tests and short- and long duration static firings including gimbaling and throttling. The test program was conducted on the S1-C test stand (Position B-2) at the National Space Technology Laboratories (NSTL)/Stennis Space Center. 3 tanking tests and 20 hot fire tests conducted between December 21 1 1977 and December 17, 1980 Configuration: The main propulsion test article consisted of the three space shuttle main engines, flightweight external tank, flightweight aft fuselage, interface section and a boilerplate mid/fwd fuselage truss structure.

  18. Dose-response curve of a microfluidic magnetic bead-based surface coverage sandwich assay.

    PubMed

    Cornaglia, Matteo; Trouillon, Raphaël; Tekin, H Cumhur; Lehnert, Thomas; Gijs, Martin A M

    2015-09-25

    Magnetic micro- and nanoparticles ('magnetic beads') have been used to advantage in many microfluidic devices for sensitive antigen (Ag) detection. Today, assays that use as read-out of the signal the number count of immobilized beads on a surface for quantification of a sample's analyte concentration have been among the most sensitive and have allowed protein detection lower than the fgmL(-1) concentration range. Recently, we have proposed in this category a magnetic bead surface coverage assay (Tekin et al., 2013 [1]), in which 'large' (2.8μm) antibody (Ab)-functionalized magnetic beads captured their Ag from a serum and these Ag-carrying beads were subsequently exposed to a surface pattern of fixed 'small' (1.0μm) Ab-coated magnetic beads. When the system was exposed to a magnetic induction field, the magnet dipole attractive interactions between the two bead types were used as a handle to approach both bead surfaces and assist with Ag-Ab immunocomplex formation, while unspecific binding (in absence of an Ag) of a large bead was reduced by exploiting viscous drag flow. The dose-response curve of this type of assay had two remarkable features: (i) its ability to detect an output signal (i.e. bead number count) for very low Ag concentrations, and (ii) an output signal of the assay that was non-linear with respect to Ag concentration. We explain here the observed dose-response curves and show that the type of interactions and the concept of our assay are in favour of detecting the lowest analyte concentrations (where typically either zero or one Ag is carried per large bead), while higher concentrations are less efficiently detected. We propose a random walk process for the Ag-carrying bead over the magnetic landscape of small beads and this model description explains the enhanced overall capture probability of this assay and its particular non-linear dose response curves.

  19. AgI/Ag{sub 3}PO{sub 4} hybrids with highly efficient visible-light driven photocatalytic activity

    SciTech Connect

    Katsumata, Hideyuki; Hayashi, Takahiro; Taniguchi, Masanao; Suzuki, Tohru; Kaneco, Satoshi

    2015-03-15

    Highlights: • AgI/Ag{sub 3}PO{sub 4} hybrid was prepared via an in situ anion-exchange method. • AgI/Ag{sub 3}PO{sub 4} displays the excellent photocatalytic activity under visible light. • AgI/Ag{sub 3}PO{sub 4} readily transforms to be Ag@AgI/Ag{sub 3}PO{sub 4} system. • h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization over AgI/Ag{sub 3}PO{sub 4}. • The activity enhancement is ascribed to a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI. - Abstract: Highly efficient visible-light-driven AgI/Ag{sub 3}PO{sub 4} hybrid photocatalysts with different mole ratios of AgI were prepared via an in situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgI/Ag{sub 3}PO{sub 4} photocatalysts displayed the higher photocatalytic activity than pure Ag{sub 3}PO{sub 4} and AgI for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgI/Ag{sub 3}PO{sub 4} with 80% of AgI exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgI/Ag{sub 3}PO{sub 4} readily transformed to be Ag@AgI/Ag{sub 3}PO{sub 4} system while the photocatalytic activity of AgI/Ag{sub 3}PO{sub 4} remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h{sup +} and O{sub 2}{sup ·−} play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgI/Ag{sub 3}PO{sub 4} hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag{sub 3}PO{sub 4}, Ag and AgI, in which Ag nanoparticles act as the charge separation center.

  20. Element-specific study of epitaxial NiO/Ag/CoO/Fe films grown on vicinal Ag(001) using photoemission electron microscopy

    SciTech Connect

    Meng, Y.; Li, J.; Tan, A.; Jin, E.; Son, J.; Park, J. S.; Doran, A.; Young, A. T.; Scholl, A.; Arenholz, E.; Wu, J.; Hwang, C.; Zhao, H. W.; Qiu, Z. Q.

    2011-01-10

    NiO/Ag/CoO/Fe single crystalline films are grown epitaxially on a vicinal Ag(001) substrate using molecular beam epitaxy and investigated by photoemission electron microscopy. We find that after zero-field cooling, the in-plane Fe magnetization switches from parallel to perpendicular direction of the atomic steps of the vicinal surface at thinner CoO thickness but remains in its original direction parallel to the steps at thicker CoO thickness. CoO and NiO domain imaging result shows that both CoO/Fe and NiO/CoO spins are perpendicularly coupled, suggesting that the Fe magnetization switching may be associated with the rotatable-frozen spin transition of the CoO film.

  1. Tailoring the magnetoimpedance effect of NiFe/Ag multilayer

    NASA Astrophysics Data System (ADS)

    Corrêa, M. A.; Bohn, F.; Chesman, C.; da Silva, R. B.; Viegas, A. D. C.; Sommer, R. L.

    2010-07-01

    The magnetoimpedance (MI) effect was investigated in NiFe/Ag multilayered (ML) and ML/SiO2/Ag/SiO2/ML structured multilayered (SD) ferromagnetic films grown by magnetron sputtering. The MI measurements were performed with an impedance analyzer over a wide frequency range, from 10 MHz to 1.8 GHz. Sample geometries are mainly responsible for the different MI behaviours and by considering the entire frequency range, distinct mechanisms responsible for MI changes were associated. For the ML sample, a maximum value of 80%, associated with the appearance of ferromagnetic resonance (FMR), was reached at around 1 GHz. For the SD sample, the striking feature is the existence of two distinct frequency ranges with high MI% values of 80% at around 100 MHz, related to the skin and magnetoinductive effects, and of 120% at around 1 GHz, associated with the strong skin and FMR effect.

  2. Work function measurement for Ag-TCNQ (TCNQ = tetracyanoquinodimethane) nanowires.

    PubMed

    Ye, Chunnuan; Zheng, Kaibo; Chen, Guorong

    2012-08-01

    The Ag-TCNQ (TCNQ = tetracyanoquinodimethane) nanowires synthesized by a vapor transport reaction exhibit promising field emission properties. Their effective work function at high applied electric field was estimated to be about 1.70 eV according to the Fowler-Nordheim (F-N) theory. In this work, we directly measured the intrinsic work function of Ag-TCNQ nanowires via the ultraviolet photoemission spectroscopy (UPS). According to the threshold binding energy, the work function is obtained to be 5.45 eV, which shows a large discrepancy with the preivous estimation based on F-N theory. The reductive effecitive work function during the field emission is mainly attributed to the morphology-induced enhancement of the nanowire array.

  3. Photocatalytic Performances of Ag3PO4 Polypods for Degradation of Dye Pollutant under Natural Indoor Weak Light Irradiation.

    PubMed

    Teng, Fei; Liu, Zailun; Zhang, An; Li, Min

    2015-08-18

    It is still a big challenge for Ag3PO4 to be applied in practice mainly because of its low stability resistant to photo corrosion, although it is an efficient photocatalyst. Herein, we have mainly investigated its activity and stability under indoor weak light for the degradation of dye pollutants. It is amazing that under indoor weak light irradiation, rhodamine B (RhB) can be completely degraded by Ag3PO4 polypods after 36 h, but only 18% of RhB by N-doped TiO2 after 120 h. It is found that under indoor weak light irradiation, the degradation rate (0.08099 h(-1)) of RhB over Ag3PO4 polypods are 46 times higher than that (0.00173 h(-1)) of N-doped TiO2. The high activity of Ag3PO4 polypods are mainly attributed to the three-dimensional branched nanostructure and high-energy {110} facets exposed. After three cycles, surprisingly, Ag3PO4 polypods show a high stability under indoor weak light irradiation, whereas Ag3PO4 have been decomposed into Ag under visible light irradiation with an artificial Xe light source. This natural weak light irradiation strategy could be a promising method for the other unstable photocatalysts in the degradation of environmental pollutants.

  4. Lasting antibacterial activities of Ag-TiO2/Ag/a-TiO2 nanocomposite thin film photocatalysts under solar light irradiation.

    PubMed

    Akhavan, O

    2009-08-01

    Photodegradation of Escherichia coli bacteria in presence of Ag-TiO(2)/Ag/a-TiO(2) nanocomposite film with an effective storage of silver nanoparticles was investigated in the visible and the solar light irradiations. The nanocomposite film was synthesized by sol-gel deposition of 30 nm Ag-TiO(2) layer on approximately 200 nm anatase(a-)TiO(2) film previously doped by silver nanoparticles. Both Ag/a-TiO(2) and Ag-TiO(2)/Ag/a-TiO(2) films were transparent with a SPR absorption band at 412 nm. Depth profile X-ray photoelectron spectroscopy showed metallic silver nanoparticles with diameter of 30 nm and fcc crystalline structure were self-accumulated on the film surface at depth of 5 nm of the TiO(2) layer and also at the interface of the Ag-TiO(2) and a-TiO(2) films (at depth of 30 nm). Both OH(-) bounds and H(2)O contents were concentrated on the film surface and at the interface, as a profit in releasing more ionic (not metallic) silver nanoparticles. Antibacterial activity of the nanocomposite film against E. coli bacteria was 5.1 times stronger than activity of the a-TiO(2), in dark. Photo-antibacterial activity of the nanocomposite film exposed by the solar light was measured 1.35 and 6.90 times better than activity of the Ag/a-TiO(2) and a-TiO(2), respectively. The main mechanism for silver ion releasing was inter-diffusion of water and silver nanoparticles through pores of the TiO(2) layer. Durability of the nanocomposite film was at least 11 times higher than the Ag/a-TiO(2) film. Therefore, the Ag-TiO(2)/Ag/a-TiO(2) photocatalyst can be nominated as one of the effective and long-lasting antibacterial nanocomposite materials.

  5. The cardiovascular response to the AGS

    NASA Technical Reports Server (NTRS)

    Cardus, David; Mctaggart, Wesley G.

    1993-01-01

    This paper reports the preliminary results of experiments on human subjects conducted to study the cardiovascular response to various g-levels and exposure times using an artificial gravity simulator (AGS). The AGS is a short arm centrifuge consisting of a turntable, a traction system, a platform and four beds. Data collection hardware is part of the communication system. The AGS provides a steep acceleration gradient in subjects in the supine position.

  6. Aqueous synthesis of Ag and Mn co-doped In2S3/ZnS quantum dots with tunable emission for dual-modal targeted imaging.

    PubMed

    Lai, Pei-Yu; Huang, Chih-Ching; Chou, Tzung-Han; Ou, Keng-Liang; Chang, Jia-Yaw

    2017-03-01

    Here, we present the microwave-assisted synthesis of In2S3/ZnS core/shell quantum dots (QDs) co-doped with Ag(+) and Mn(2+) (referred to as AgMn:In2S3/ZnS). Ag(+) altered the optical properties of the host QDs, whereas the spin magnetic moment (S=5/2) of Mn(2+) efficiently induced the longitudinal relaxation of water protons. To the best of our knowledge, this is the first report of the aqueous synthesis of color-tunable AgMn:In2S3/ZnS core/shell QDs with magnetic properties. The synthetic procedure is rapid, facile, reproducible, and scalable. The obtained QDs offered a satisfactory quantum yield (45%), high longitudinal relaxivity (6.84s(-1)mM(-1)), and robust photostability. In addition, they exhibited excellent stability over a wide pH range (5-12) and high ionic strength (0.15-2.0M NaCl). As seen by confocal microscopy and magnetic resonance imaging, AgMn:In2S3/ZnS conjugated to hyaluronic acid (referred to as AgMn:In2S3/ZnS@HA) efficiently and specifically targeted cluster determinant 44, a receptor overexpressed on cancer cells. Moreover, AgMn:In2S3/ZnS@HA showed negligible cytotoxicity in vitro and in vivo, rendering it a promising diagnostic probe for dual-modal imaging in clinical applications.

  7. The upgraded rf system for the AGS and high intensity proton beams

    SciTech Connect

    Brennan, J.M.

    1995-05-01

    The AGS has been upgraded over the past three years to produce a record beam intensity of 6 {times} 10{sup 13} protons per pulse for the fixed-target physics program. The major elements of the upgrade are: the new 1.5 GeV Booster synchrotron, the main magnet power supply, a high frequency longitudinal dilution cavity, a feedback damper for transverse instabilities, a fast gamma transition jump system, and a new high-power rf system. The new rf system and its role in achieving the high intensity goal are the subjects of this report. The rf system is heavily beam loaded, with 7 Amps of rf current in the beam and a peak power of 0.75 MW delivered to the beam by ten cavities. As an example of the scale of beam loading, at one point in the acceleration cycle the cavities are operated at 1.5 kV/gap; whereas, were it not for the new power amplifiers, the beam-induced voltage on the cavities would be over 25 kV/gap. The upgraded rf system, comprising: new power amplifiers, wide band rf feedback, improved cavities, and new low-level beam control electronics, is described. Results of measurements with beam, which characterize the system`s performance, are presented. A typical high intensity acceleration cycle is described with emphasis on the key challenges of beam loading.

  8. Transformation from Ag@Ag3PO4 to Ag@Ag2SO4 hybrid at room temperature: preparation and its visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Wei, Ting; Gao, Shanmin; Wang, Qingyao; Xu, Hui; Wang, Zeyan; Huang, Baibiao; Dai, Ying

    2017-02-01

    In the present study, Ag/Ag2SO4 hybrid photocatalysts were obtained via a facile redox-precipitation reaction approach by using Ag@Ag3PO4 nanocomposite as the precursor and KMnO4 as the oxidant. Multiple techniques, such as X-ray diffraction pattern (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and Brunauer-Emmett-Teller (BET), photocurrent and electrochemical impedance spectroscopy (EIS), were applied to investigate the structures, morphologies, optical, and electronic properties of as-prepared samples. The photocatalytic activities were evaluated by photodegradation of organic rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. It was found that pure Ag2SO4 can partially transform into metallic Ag during the photocatalytic degradation of organic pollutants, but the Ag/Ag2SO4 hybrids can maintain its structure stability and show enhanced visible light photocatalytic activity because of the surface plasma resonance effect of the metallic Ag.

  9. Space Shuttle Era: Main Engines

    NASA Video Gallery

    Producing 500,000 pounds of thrust from a package weighing only 7,500 pounds, the Space Shuttle Main Engines are one of the shining accomplishments of the shuttle program. The success did not come ...

  10. Surface plasmon resonances behavior in visible light of non-metal perovskite oxides AgNbO{sub 3}

    SciTech Connect

    Zhou, Fei; Zhu, Jingchuan Liu, Yong; Zhao, Xiaoliang; Lai, Zhonghong

    2014-12-08

    We investigate the surface plasmon resonances (SPRs) behavior of silver niobate (AgNbO{sub 3}) experimentally and theoretically. Result shows that the localized SPRs (LSPRs) of AgNbO{sub 3} combining with its interband transitions enlarge the absorption band across the whole ultraviolet-visible range. The LSPRs behavior in visible-light is mainly ascribed to the metal-like state of silver ion and self-assembled microstructures of AgNbO{sub 3} microcrystal. The ab initio density functional theory calculations are carried out to obtain the further insight of the SPRs behaviors. Theoretical study indicates that the Ag atoms are weakly bound in the perovskite structure, leading to a metal-like state, which was the key factor to SPRs behavior of AgNbO{sub 3}.

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

    PubMed

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

    2016-03-01

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

  12. LSRA with Shuttle main gear

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A space shuttle landing gear system is visible between the two main landing gear components on this NASA CV-990, modified as a Landing Systems Research Aircraft. The space shuttle landing gear test unit, operated by a high-pressure hydraulic system, allowed engineers to assess and document the performance of space shuttle main and nose landing gear systems, tires and wheel assemblies, plus braking and nose wheel steering performance.

  13. Single step electrochemical synthesis of hydrophilic/hydrophobic Ag5 and Ag6 blue luminescent clusters.

    PubMed

    Santiago González, Beatriz; Blanco, M C; López-Quintela, M Arturo

    2012-12-21

    Well-defined Ag(5) and Ag(6) dodecanethiol/tetrabutyl ammonium-protected clusters were prepared by a one-pot electrochemical method. Ag clusters show bright and photostable emissions. The presence of a dual capping renders the silver clusters soluble in both organic and aqueous solvents.

  14. Synthesis of Cu-Ag@Ag particles using hyperbranched polyester as template

    NASA Astrophysics Data System (ADS)

    Han, Wen-Song

    2015-07-01

    In this manuscript, the third-generation hyperbranched polyester was synthesized with 2, 2-dimethylol propionic acid as AB2 monomer and pentaerythrite as core molecule by using step by step polymerization process at first. Then, the Cu-Ag particles were prepared by co-reduction of silver nitrate and copper nitrate with ascorbic acid in the aqueous solution using hyperbranched polyester as template. Finally, the Cu-Ag@Ag particles were prepared by coating silver on the surface of Cu-Ag particles by reduction of silver nitrate. The synthesized hyperbranched polyester and Cu-Ag@Ag particles were characterized by Fourier transform infrared (FT-IR) spectroscopy, UV-vis spectra, x-ray diffraction, Laser light scattering, thermogravimetric analysis (TGA) and SEM. UV-vis spectra results showed that the Cu-Ag@Ag particles had a strong absorption band at around 420 nm. Laser light scattering and SEM studies confirmed that the most frequent particle sizes of Cu-Ag@Ag particles were 1.2 um. TGA results indicated that the Cu-Ag@Ag particles had good thermal stability. [Figure not available: see fulltext.

  15. An Au/AgBr-Ag heterostructure plasmonic photocatalyst with enhanced catalytic activity under visible light.

    PubMed

    Purbia, Rahul; Paria, Santanu

    2017-01-17

    This study reports an easy synthesis protocol of a novel bimetallic silver halide (Au/AgBr-Ag) plasmonic heterostructure as a visible light induced photocatalyst. In this process, first CTAB capped Au NPs were coated with AgBr, and then Ag nanoparticles were formed on the surface of AgBr by photoreduction, while exposing to daylight at room temperature. The presence of Au and Ag improves the visible absorption ability of NPs and avoids charge recombination of the semiconductor AgBr during photoexcitation, which in turn enhances 16 and 8.9 fold the photocatalytic efficiency of Rhodamine B dye degradation under visible light irradiation compared to that of pure AgBr and AgBr/Ag, respectively. The recycling tests of the photocatalyst show only ∼8.7% decrease in efficiency after the 5(th) cycle of reuse without changing the morphology. During the photocatalytic process, active superoxide radicals (O2˙(-)) play a major role, proved through scavenger trapping and photoluminescence experiments. The presence of two plasmonic metals (Au and Ag) in the heterostructure helps to improve visible light absorption as well as avoid charge recombination of the semiconductor AgBr to act as a better photocatalyst. Since this heteronanostructure can be easily synthesized by a one-step method, this study could provide a new approach for the development of efficient bimetallic/semiconductor halide plasmonic photocatalysts with enhanced visible absorption and better charge separation.

  16. Highly efficient visible light plasmonic photocatalyst Ag@Ag(Br,I).

    PubMed

    Wang, Peng; Huang, Baibiao; Zhang, Qianqian; Zhang, Xiaoyang; Qin, Xiaoyan; Dai, Ying; Zhan, Jie; Yu, Jiaoxian; Liu, Haixia; Lou, Zaizhu

    2010-09-03

    The new plasmonic photocatalyst Ag@Ag(Br,I) was synthesized by the ion-exchange process between the silver bromide and potassium iodide, then by reducing some Ag(+) ions in the surface region of Ag(Br,I) particles to Ag(0) species. Ag nanoparticles are formed from Ag(Br,I) by the light-induced chemical reduction reaction. The Ag@Ag(Br,I) particles have irregular shapes with their sizes varying from 83 nm to 1 mum. The as-grown plasmonic photocatalyst shows strong absorption in the visible light region because of the plasmon resonance of Ag nanoparticles. The ability of this compound to reduce Cr(VI) under visible light was compared with those of other reference photocatalyst. The plasmonic photocatalyst is shown to be highly efficient under visible light. The stability of the photocatalyst was examined by X-ray diffraction and X-ray photoelectron spectroscopy. The XRD pattern and XPS spectra prove the stability of the plasmonic photocatalyst Ag@Ag(Br,I).

  17. Synthesis of Ag-Mn3O4 core-shell nanorods and Mn3O4 nanotubes from sacrificial Ag nanorod templates.

    PubMed

    Dong, Hyunbae; Koh, Eoi Kwan; Lee, Sang-Yup

    2009-11-01

    Our research focuses on the preparation of Ag-Mn3O4 core-shell nanorods and Mn3O4 nanotubes which have various engineering applications. Hausmannite manganese oxide (Mn3O4) nanotubes were synthesized via a galvanic replacement reaction at mild reaction conditions. The Mn3O4 nanotubes were prepared by solidification of manganese ions on a sacrificial silver nanorod due to the standard reduction potential difference between solid silver and manganese ions. The Mn ions were reduced to solid while the solid Ag rod was oxidized to ions. Ag-Mn3O4 core-shell nanorods and Mn3O4 nanotubes were simply prepared by changing the amount of manganese ions. The Mn3O4 layer in the nanorods and nanotubes had a Hausmannite crystalline structure and showed weak hysteresis of magnetism. This weak magnetism is likely due to the diamagnetic property of silver and multiple magnetic domain of Mn3O4. This simple replacement reaction could be applied to various oxide nanotube fabrications with exact shape control.

  18. Negligible shift of 3Ag- potential in longer-chain carotenoids as revealed by a single persistent peak of 3Ag-→1Ag- stimulated emission followed by 3Ag-←1Ag- transient-absorption

    NASA Astrophysics Data System (ADS)

    Li, Chunyong; Miki, Takeshi; Kakitani, Yoshinori; Koyama, Yasushi; Nagae, Hiroyoshi

    2007-12-01

    Upon excitation of lycopene, anhydrorhodovibrin or spirilloxanthin to the 1Bu+(0) state, stimulated emission followed by transient-absorption was observed as a single peak with the 3Ag-(0) energy that had been determined by measurement of resonance-Raman excitation profiles. This observation was explained in terms of negligible shift of the 3Ag- potential, in reference to the 1Ag- potential, where only the 3Ag-(υ)→1Ag-(υ) emission and the 3Ag-(υ)←1Ag-(υ) absorption become allowed during the vibrational relaxation of υ = 2 → 1 → 0, starting from the 3Ag-(2) level generated by diabatic internal conversion from the 1Bu+(0) level, in anhydrorhodovibrin, for example.

  19. Silver deposited carboxymethyl chitosan-grafted magnetic nanoparticles as dual action deliverable antimicrobial materials.

    PubMed

    Vo, Duc-Thang; Sabrina, Sabrina; Lee, Cheng-Kang

    2017-04-01

    Carboxymethyl chitosan (CMCS) was known to have a much better antimicrobial activity than chitosan due to the increased cationic -NH3(+) groups resulted from the intra- and intermolecular interactions between the carboxyl and amino groups. CMCS was grafted onto the surface of silica coated magnetic nanoparticles (MNPs) to obtain magnetically retrievable and deliverable antimicrobial nanoparticles (MNPs@CMCS). The presence of carboxylate groups in CMCS not only enhanced antimicrobial activity but also enabled Ag ions chelating ability to induce the in situ formation of Ag nanoparticles (AgNPs). The deposition of AgNPs on the surface of MNPs@CMCS could significantly increase its antimicrobial activity against planktonic cells due to the dual action of CMCS and AgNPs. Due to its high magnetism, the as-prepared MNPs@CMCS-Ag could be efficiently delivered into an existing biofilm under the guidance of an applied magnetic field. Without direct contact, the Ag ions and/or radical oxygen species (ROS) released from the deposited Ag nanoparticles could effectively kill the bacteria embedded in the extracellular polymeric substances (EPS) matrix of biofilm.

  20. Half-life determination for 108Ag and 110Ag

    NASA Astrophysics Data System (ADS)

    Zahn, Guilherme S.; Genezini, Frederico A.

    2014-11-01

    In this work, the half-life of the short-lived silver radionuclides 108Ag and 110Ag were measured by following the activity of samples after they were irradiated in the IEA-R1 reactor. The results were then fitted using a non-paralizable dead time correction to the regular exponential decay and the individual half-life values obtained were then analyzed using both the Normalized Residuals and the Rajeval techniques, in order to reach the most exact and precise final values. To check the validity of dead-time correction, a second correction method was also employed by means of counting a long-lived 60Co radioactive source together with the samples as a livetime chronometer. The final half-live values obtained using both dead-time correction methods were in good agreement, showing that the correction was properly assessed. The results obtained are partially compatible with the literature values, but with a lower uncertainty, and allow a discussion on the last ENSDF compilations' values.

  1. Main experimental results of the Phebus Severe Fuel Damage Program

    SciTech Connect

    Gonnier, C. )

    1993-01-01

    The main objective of this program is to improve our knowledge about the early phase of a pressurized water reactor in-vessel core melt degradation in a temperature range up to 2800 K. The experimental program performed from December 1986 to June 1989 consists of six in-pile experiments with 21 fresh fuel rod bundles of 0.8 m active length. It is divided into two series of tests: (1) The first one (B9, B9R, B9+) is mainly devoted to the oxidation phenomenon and its consequences for fuel degradation. This series is characterized by high oxidation rates. (2) The second series [C3, C3+, Ag-In-CD (AIC)] is characterized by low oxidation rates of the cladding in order to study the interaction between the remaining Zircaloy and the other materials: interactions with Inconel and UO[sub 2] for C3 and C3+ tests and interactions with the Ag-In-Cd alloy and stainless steel of the control rod for the AIC test.

  2. Study on the limiting factor of critical current in Ag-Bi2223 tapes

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Ding, S. Y.; Luo, H.; Leng, X.; Lin, J. W.

    2003-04-01

    The silver sheathed tapes of Ag-Bi 2- xPb xSr 2Ca 2-Cu 3O 7- y (Ag-Bi2223) were fabricated by usual process. The limiting factor of the critical current density jc of the tapes was studied. V- I characteristic was performed for the tapes immersed in liquid nitrogen with and without magnetic fields. Hysteresis loop of V- I curve was observed. A model based on polycrystalline superconductors was proposed to account for this kind of hysteresis. The result shows that in our Ag-Bi2223 tapes the weak link is the key factor limiting the global critical current. The measurement of V- I loop can be an effective method to check whether there exist harmful weak links in polycrystalline samples.

  3. Connectivity and limitation of critical current in Bi-Pb-Sr-Ca-Cu/Ag tapes

    NASA Astrophysics Data System (ADS)

    Müller, K.-H.; Andrikidis, C.; Du, J.; Leslie, K. E.; Foley, C. P.

    1999-07-01

    We have shown experimentally that the remanent magnetic moments of Y-Ba-Cu-O thin-film networks and of Bi-2223/Ag monofilamentary tapes show remarkable similarities, as their magnetic moments are both composed of intersquare (intergrain) and intrasquare (intragrain) magnetic moments. Starting from the geometrical definition of connectivity in a thin-film network, we show that connectivity in a Bi-2223/Ag monofilamentary tape is solely defined by the ratio of the average grain size to the width of the superconducting core and by the ratio of the intergrain to intragrain remanent magnetic moments at saturation. The measured upper limit for the connectivities ranged from 4.2×10-3 in a tape with low critical current density Jc to 2.9×10-2 in a tape with Jc(77 K,0 T)~=2×108 A m-2. Our study reveals that even good Bi-2223/Ag tapes suffer from very low grain connectivity. We estimate that in the case of perfect connectivity a Jc(77 K,0 T) between 8×109 and 6×1010 A m-2 would be achievable.

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

    SciTech Connect

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

    2007-06-25

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

  5. Photodegradation of Eosin Y Using Silver-Doped Magnetic Nanoparticles

    PubMed Central

    Alzahrani, Eman

    2015-01-01

    The purification of industrial wastewater from dyes is becoming increasingly important since they are toxic or carcinogenic to human beings. Nanomaterials have been receiving significant attention due to their unique physical and chemical properties compared with their larger-size counterparts. The aim of the present investigation was to fabricate magnetic nanoparticles (MNPs) using a coprecipitation method, followed by coating with silver (Ag) in order to enhance the photocatalytic activity of the MNPs by loading metal onto them. The fabricated magnetic nanoparticles coated with Ag were characterised using different instruments such as a scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDAX) spectroscopy, and X-ray diffraction (XRD) analysis. The average size of the magnetic nanoparticles had a mean diameter of about 48 nm, and the average particle size changed to 55 nm after doping. The fabricated Ag-doped magnetic nanoparticles were used for the degradation of eosin Y under UV-lamp irradiation. The experimental results revealed that the use of fabricated magnetic nanoparticles coated with Ag can be considered as reliable methods for the removal of eosin Y since the slope of evaluation of pseudo-first-order rate constant from the slope of the plot between ln⁡(Co/C) and the irradiation time was found to be linear. Ag-Fe3O4 nanoparticles would be considered an efficient photocatalyst to degrade textile dyes avoiding the tedious filtration step. PMID:26617638

  6. Preparation, characterization, and antibacterial activity of NiFe2O4/PAMA/Ag-TiO2 nanocomposite

    NASA Astrophysics Data System (ADS)

    Allafchian, Alireza; Jalali, Seyed Amir Hossein; Bahramian, Hamid; Ahmadvand, Hossein

    2016-04-01

    We have described a facile fabrication of silver deposited on the TiO2, Poly Acrylonitrile Co Maleic Anhydride (PAMA) polymer and nickel ferrite composite (NiFe2O4/PAMA/Ag-TiO2) through a three-step procedure. A pre-synthesized NiFe2O4 was first coated with PAMA polymer and then Ag-TiO2 was deposited on the surface of PAMA polymer shell. After the characterization of this three-component composite by various techniques, such as FTIR, XRD, FESEM, BET, TEM and VSM, it was impregnated in standard antibiotic discs. The antibacterial activity of NiFe2O4/PAMA/Ag-TiO2 nanocomposite was investigated against some gram positive and gram negative bacteria by employing disc diffusion assay and then compared with that of naked NiFe2O4, NiFe2O4/Ag, AgNPs and NiFe2O4/PAMA. The results demonstrated that the AgNPs, when embedded in TiO2 and combined with NiFe2O4/PAMA, became an excellent antibacterial agent. The NiFe2O4/PAMA/Ag-TiO2 nanocomposite could be readily separated from water solution after the disinfection process by applying an external magnetic field.

  7. Accretion onto Pre-Main-Sequence Stars

    NASA Astrophysics Data System (ADS)

    Hartmann, Lee; Herczeg, Gregory; Calvet, Nuria

    2016-09-01

    Accretion through circumstellar disks plays an important role in star formation and in establishing the properties of the regions in which planets form and migrate. The mechanisms by which protostellar and protoplanetary disks accrete onto low-mass stars are not clear; angular momentum transport by magnetic fields is thought to be involved, but the low-ionization conditions in major regions of protoplanetary disks lead to a variety of complex nonideal magnetohydrodynamic effects whose implications are not fully understood. Accretion in pre-main-sequence stars of masses ≲1M⊙ (and in at least some 2-3-M⊙ systems) is generally funneled by the stellar magnetic field, which disrupts the disk at scales typically of order a few stellar radii. Matter moving at near free-fall velocities shocks at the stellar surface; the resulting accretion luminosities from the dissipation of kinetic energy indicate that mass addition during the T Tauri phase over the typical disk lifetime ˜3 Myr is modest in terms of stellar evolution, but is comparable to total disk reservoirs as estimated from millimeter-wave dust emission (˜10-2 M⊙). Pre-main-sequence accretion is not steady, encompassing timescales ranging from approximately hours to a century, with longer-timescale variations tending to be the largest. Accretion during the protostellar phase—while the protostellar envelope is still falling onto the disk—is much less well understood, mostly because the properties of the central obscured protostar are difficult to estimate. Kinematic measurements of protostellar masses with new interfometric facilities should improve estimates of accretion rates during the earliest phases of star formation.

  8. Electromagnetic properties of Bi-2223/Ag concentric tapes

    SciTech Connect

    Majoros, M.; Polak, M.; Kvitkovic, J.; Suchon, D.; Martini, L.; Ottoboni, V.; Zannella, S.

    1996-07-01

    It is well established that near the silver interface highly textured Bi-2223 layers compared to the inner ceramic core may be obtained. Thus Bi-2223 multilayered concentric tapes with silver matrix are very promising in increasing transport critical current densities. In the present work the authors report on the electromagnetic characterization of short tapes having in their cross-section a very thin HTS flattened ring with Ag inside and outside of it. The samples were prepared by the powder in tube method and have self-field critical current densities J{sub c} of the order of 3 {times} 10{sup 4} A/cm{sup 2} at 77 K. Transport and SQUID magnetization measurements revealed weak link nature of the samples in low magnetic fields. Large transport J{sub c}(B) hysteresis was observed at 4.2 K and magnetic fields up to 20 T. Magnetic field profiles measurements with miniature Hall sensors are in qualitative accordance with model calculations supposing homogeneous current density distribution across the superconducting core.

  9. Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

    SciTech Connect

    Singh, Anamika; Dutta, Dimple P.; Ballal, A.; Tyagi, A.K.; Fulekar, M.H.

    2014-03-01

    Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

  10. Effects of soil and dietary exposures to Ag nanoparticles and AgNO₃ in the terrestrial isopod Porcellionides pruinosus.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Jurkschat, Kerstin; Soares, Amadeu M V M; Loureiro, Susana

    2015-10-01

    The effects of Ag-NPs and AgNO3 on the isopod Porcellionides pruinosus were determined upon soil and dietary exposures. Isopods avoided Ag in soil, with EC50 values of ∼16.0 and 14.0 mg Ag/kg for Ag-NPs and AgNO3, respectively. Feeding inhibition tests in soil showed EC50s for effects on consumption ratio of 127 and 56.7 mg Ag/kg, respectively. Although similar EC50s for effects on biomass were observed for nanoparticulate and ionic Ag (114 and 120 mg Ag/kg dry soil, respectively), at higher concentrations greater biomass loss was found for AgNO3. Upon dietary exposure, AgNO3 was more toxic, with EC50 for effects on biomass change being >1500 and 233 mg Ag/kg for Ag-NPs and AgNO3, respectively. The difference in toxicity between Ag-NPs and AgNO3 could not be explained from Ag body concentrations. This suggests that the relation between toxicity and bioavailability of Ag-NPs differs from that of ionic Ag in soils.

  11. Synthesis and characterization of graphene oxide modified AgBr nanocomposites with enhanced photocatalytic activity and stability under visible light

    NASA Astrophysics Data System (ADS)

    Zhang, Du; Tang, Hua; Wang, Yuqi; Wu, Kongqiang; Huang, Hong; Tang, Guogang; Yang, Jin

    2014-11-01

    Novel visible-light-driven graphene oxide (GO)/AgBr nanocomposites were synthesized by a facile solution method. The GO/AgBr nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoemission spectroscopy (XPS) analysis, UV-vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectra (FTIR), and Raman spectra. The results indicated that AgBr nanoparticles were evenly distributed on the surface of GO and the heterostructures were formed. The photocatalytic activity of the as-prepared nanocomposites was evaluated by using Rhodamine B (RhB), Methylene blue (MB) and Methyl orange (MO) as target organic pollutants. The nanocomposites exhibit excellent photocatalytic activity for all of three dyes. Compared with bare AgBr particles, the GO/AgBr nanocomposites show better photocatalytic properties toward RhB pollutants. Additionally, the radical scavengers experiment indicated that O2rad - radicals was the main reactive species for the RhB degradation under visible light. The increased photocatalytic activity of the GO/AgBr nanocomposites was attributed to the strong coupling between GO and AgBr, which facilitated interfacial charge transfer and inhibited electron-hole recombination. A photocatalytic mechanism of GO/AgBr nanocomposites was also proposed.

  12. Substantivity of Ag-Ca-Si mesoporous nanoparticles on dentin and its ability to inhibit Enterococcus faecalis.

    PubMed

    Fan, Wei; Wu, Yujie; Ma, Tengjiao; Li, Yanyun; Fan, Bing

    2016-01-01

    The main purpose of this study was to investigate the substantivity of Ag-Ca-Si mesoporous nanoparticles (Ag-MCSNs) on dentin and its residual antibacterial effects against Enterococcus faecalis. Ag-MCSNs were fabricated and characterized, ion release profile and pH were tested, and the ability to inhibit planktonic E. faecalis as well as the cytotoxicity was evaluated. Dentin slices were medicated with Ca(OH)2 paste, 2 % chlorhexidine gel and Ag-MCSNs paste for 7 days and then irrigated. Dentin slices were then immersed in E. faecalis suspension for 6 days and then transferred to fresh brain heart infusion solution. The optical density value within 10 h after immersing and transferring were measured and compared among groups. Results indicated that Ag-MCSNs showed high pH, sustained Ag(+)-Ca(2+)-SiO3 (2-) ion release, and high substantivity on dentin. The Ag-MCSNs exhibited strong antibacterial effects against planktonic E. faecalis and much better residual inhibition effects against E. faecalis growth on dentin than Ca(OH)2 paste (P < 0.05). The Ag-MCSNs showed excellent antibacterial ability against E. faecalis and high substantivity on dentin, which might be developed to a new effective intra-canal medicament for human teeth.

  13. Photocatalytic oxidation removal of Hg0 using ternary Ag/AgI-Ag2CO3 hybrids in wet scrubbing process under fluorescent light

    NASA Astrophysics Data System (ADS)

    Zhang, Anchao; Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao; Xiang, Jun

    2017-01-01

    A series of ternary Ag/AgI-Ag2CO3 photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg0 removal in a wet scrubbing reactor. The hybrids were characterized by N2 adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg0 removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg0 removal. NO exhibited significant effect on Hg0 removal in comparison to SO2. Among these ternary Ag/AgI-Ag2CO3 hybrids, Ag/AgI(0.1)-Ag2CO3 showed the highest Hg0 removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag2CO3 and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag0 NPs). The trapping studies of reactive radicals showed that the superoxide radicals (rad O2-) may play a key role in Hg0 removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg0 removal over Ag/AgI(0.1)-Ag2CO3 hybrid under fluorescent light was proposed.

  14. Magnetic patterning: local manipulation of the intergranular exchange coupling via grain boundary engineering

    PubMed Central

    Huang, Kuo-Feng; Liao, Jung-Wei; Hsieh, Cheng-Yu; Wang, Liang-Wei; Huang, Yen-Chun; Wen, Wei-Chih; Chang, Mu-Tung; Lo, Shen-Chuan; Yuan, Jun; Lin, Hsiu-Hau; Lai, Chih-Huang

    2015-01-01

    Magnetic patterning, with designed spatial profile of the desired magnetic properties, has been a rising challenge for developing magnetic devices at nanoscale. Most existing methods rely on locally modifying magnetic anisotropy energy or saturation magnetization, and thus post stringent constraints on the adaptability in diverse applications. We propose an alternative route for magnetic patterning: by manipulating the local intergranular exchange coupling to tune lateral magnetic properties. As demonstration, the grain boundary structure of Co/Pt multilayers is engineered by thermal treatment, where the stress state of the multilayers and thus the intergranular exchange coupling can be modified. With Ag passivation layers on top of the Co/Pt multilayers, we can hinder the stress relaxation and grain boundary modification. Combining the pre-patterned Ag passivation layer with thermal treatment, we can design spatial variations of the magnetic properties by tuning the intergranular exchange coupling, which diversifies the magnetic patterning process and extends its feasibility for varieties of new devices. PMID:26156786

  15. AgRISTARS documents tracking list report

    NASA Technical Reports Server (NTRS)

    Hawkins, J. L.

    1983-01-01

    A quarterly listing of documents issued and placed in the AgRISTARS tracking system is provided. The technical publications are arranged by type of documents. The reference AgRISTARS document number, title and date of publication, the issuing organization, and the National Technical Information Service reference number is given.

  16. Specialty magnets

    SciTech Connect

    Halbach, K.

    1986-07-01

    A number of basic conceptual designs are explained for magnet systems that use permanent magnet materials. Included are iron free multipoles and hybrid magnets. Also appended is a discussion of the manufacturing process and magnetic properties of some permanent magnet materials. (LEW)

  17. Graphene-Ag nanohexagonal platelets-based ink with high electrical properties at low sintering temperatures.

    PubMed

    Liu, Piao; Ma, Jin; Deng, Sha; Zeng, Kai; Deng, Dunying; Xie, Wei; Lu, Anxian

    2016-09-23

    Printed-electronics inks belong to a class of novel functional conductive inks that can be used to form high-precision conducting lines or circuits on various flexible substrates. Previous studies have reported conductive inks produced by the reduction and membrane separation method for use in flexible devices. However, it remains a challenge to synthesize conductive inks with high electrical properties at low sintering temperatures, which restricts their range of applications. Herein, we prepare inkjet-printed patterns of conductive inks consisting of Ag nanohexagonal platelets (AgNHPs) as the main component and containing graphene (GE) in different contents. It is found that GE improves the electrical conductivity of the patterns when sintering is done at relatively low temperatures. For instance, when the GE content is 0.15 mg ml(-1), the resistivity is the lowest. When sintering is done at 150 °C, the resistivity (2.7 × 10(-6) Ω · cm) of the GE-AgNHPs conductive ink (GE: 0.15 mg ml(-1)) is 14% of that of the AgNHPs conductive ink; on the other hand, after sintering at 50 °C, this ratio is 2%. It is also found that, with the increase in GE content, the resistivity of the GE-AgNHPs conductive ink increases. This study on GE-AgNHPs conductive inks sintered at low temperatures should further the development of flexible touch screens.

  18. Biodistribution, pharmacokinetics and toxicology of Ag2S near-infrared quantum dots in mice.

    PubMed

    Zhang, Yan; Zhang, Yejun; Hong, Guosong; He, Wei; Zhou, Kun; Yang, Kai; Li, Feng; Chen, Guangcun; Liu, Zhuang; Dai, Hongjie; Wang, Qiangbin

    2013-05-01

    Ag2S quantum dots (QDs) have been demonstrated as a promising near-infrared II (NIR-II, 1.0-1.4 μm) emitting nanoprobe for in vivo imaging and detection. In this work, we carefully study the long-term in vivo biodistribution of Ag2S QDs functionalized with polyethylene glycol (PEG) and systematically examine the potential toxicity of Ag2S QDs over time. Our results show that PEGylated-Ag2S QDs are mainly accumulated in the reticuloendothelial system (RES) including liver and spleen after intravenous administration and can be gradually cleared, mostly by fecal excretion. PEGylated-Ag2S QDs do not cause appreciable toxicity at our tested doses (15 and 30 mg/kg) to the treated mice over a period of 2 months as evidenced by blood biochemistry, hematological analysis and histological examinations. Our work lays a solid foundation for further biomedical applications of Ag2S QDs as an important in vivo imaging agent in the NIR-II region.

  19. Graphene-Ag nanohexagonal platelets-based ink with high electrical properties at low sintering temperatures

    NASA Astrophysics Data System (ADS)

    Liu, Piao; Ma, Jin; Deng, Sha; Zeng, Kai; Deng, Dunying; Xie, Wei; Lu, Anxian

    2016-09-01

    Printed-electronics inks belong to a class of novel functional conductive inks that can be used to form high-precision conducting lines or circuits on various flexible substrates. Previous studies have reported conductive inks produced by the reduction and membrane separation method for use in flexible devices. However, it remains a challenge to synthesize conductive inks with high electrical properties at low sintering temperatures, which restricts their range of applications. Herein, we prepare inkjet-printed patterns of conductive inks consisting of Ag nanohexagonal platelets (AgNHPs) as the main component and containing graphene (GE) in different contents. It is found that GE improves the electrical conductivity of the patterns when sintering is done at relatively low temperatures. For instance, when the GE content is 0.15 mg ml-1, the resistivity is the lowest. When sintering is done at 150 °C, the resistivity (2.7 × 10-6 Ω · cm) of the GE-AgNHPs conductive ink (GE: 0.15 mg ml-1) is 14% of that of the AgNHPs conductive ink; on the other hand, after sintering at 50 °C, this ratio is 2%. It is also found that, with the increase in GE content, the resistivity of the GE-AgNHPs conductive ink increases. This study on GE-AgNHPs conductive inks sintered at low temperatures should further the development of flexible touch screens.

  20. Spectroscopic view on the outburst activity of the symbiotic binary AG Draconis

    NASA Astrophysics Data System (ADS)

    Leedjärv, L.; Gális, R.; Hric, L.; Merc, J.; Burmeister, M.

    2016-03-01

    Variations of the emission lines in the spectrum of the yellow symbiotic star AG Draconis (AG Dra) have been studied for over 14 yr (1997-2011), using more than 500 spectra obtained with the 1.5-m telescope at Tartu Observatory, Estonia. The time interval covered includes the major (cool) outburst of AG Dra that started in 2006. The main findings can be summarized as follows. (i) The cool and hot outbursts of AG Dra can be distinguished from the variations of optical emission lines. (ii) The Raman scattered emission line of O VI at λ6825 almost disappeared during the cool outburst. (iii) The lower excitation emission lines did not change significantly during the cool outburst, but they do vary in hot outbursts and also follow orbital motion. (iv) The similarity of variations in AG Dra to those in the prototypical symbiotic star Z Andromedae allows us to suggest that a combination nova model proposed for the latter object might also be responsible for the outburst behaviour of AG Dra.

  1. Intermetallic compounds formed at the interface between Cu substrate and an Sn-9Zn-0.5Ag lead-free solder

    SciTech Connect

    Chang, T.-C.; Hon, M.-H.; Wang, M.-C

    2003-04-30

    The intermetallic compounds (IMCs) formed at the interface between Cu substrate and an Sn-9Zn-0.5Ag lead-free solder alloy have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron diffraction (ED). The XRD patterns show that the main IMCs formed at the interface of Sn-9Zn-0.5Ag/Cu are {gamma}-Cu{sub 5}Zn{sub 8} and {eta}'-Cu{sub 6}Sn{sub 5}. The Ag{sub 3}Sn IMC with orthorhombic structure was also observed at the Sn-9Zn-0.5Ag/Cu interface by TEM and ED analyses. The interfacial adhesion strength between the Cu substrate and Sn-9Zn-0.5Ag lead-free solder alloy is higher than that of the Sn-9Zn alloy due to the formation of Ag{sub 3}Sn IMC at the interface.

  2. AgPO2F2 and Ag9(PO2F2)14: the first Ag(i) and Ag(i)/Ag(ii) difluorophosphates with complex crystal structures.

    PubMed

    Malinowski, Przemysław J; Kurzydłowski, Dominik; Grochala, Wojciech

    2015-12-07

    The reaction of AgF2 with P2O3F4 yields a mixed valence Ag(I)/Ag(II) difluorophosphate salt with AgAg(PO2F2)14 stoichiometry - the first Ag(ii)-PO2F2 system known. This highly moisture sensitive brown solid is thermally stable up to 120 °C, which points at further feasible extension of the chemistry of Ag(ii)-PO2F2 systems. The crystal structure shows a very complex bonding pattern, comprising of polymeric Ag(PO2F2)14(4-) anions and two types of Ag(I) cations. One particular Ag(II) site present in the crystal structure of Ag9(PO2F2)14 is the first known example of square pyramidal penta-coordinated Ag(ii) in an oxo-ligand environment. Ag(i)PO2F2 - the product of the thermal decomposition of Ag9(PO2F2)14 - has also been characterized by thermal analysis, IR spectroscopy and X-ray powder diffraction. It has a complicated crystal structure as well, which consists of infinite 1D [Ag(I)O4/2] chains which are linked to more complex 3D structures via OPO bridges. The PO2F2(-) anions bind to cations in both compounds as bidentate oxo-ligands. The terminal F atoms tend to point inside the van der Waals cavities in the crystal structure of both compounds. All important structural details of both title compounds were corroborated by DFT calculations.

  3. Ligand and counterion control of Ag(I) architectures: assembly of a {Ag8} ring cluster mediated by hydrophobic and Ag...Ag interactions.

    PubMed

    Fielden, John; Long, De-liang; Slawin, Alexandra M Z; Kögerler, Paul; Cronin, Leroy

    2007-10-29

    A strategy combining ligand design and counterion variation has been used to investigate the assembly of silver(I) complexes. As a result, dinuclear, octanuclear, and polymeric silver(I) species have been synthesized by complexation of the rigid aliphatic amino ligands cis-3,5-diamino-trans-hydroxycyclohexane (DAHC), cis-3,5-diamino-trans-methoxycyclohexane (DAMC), and cis-3,5-diamino-trans-tert-butyldimethylsilylanyloxycyclohexane (DATC) with silver(I) triflate, nitrate, and perchlorate. The compositions of these aggregates, established by X-ray crystallography and elemental analysis, are [{Ag(DAHC)}2](CF3SO3)2 (1), [{Ag(DAMC)}2](CF3SO3)2 (2), [{Ag(DAMC)}2](NO3)2 (3), [{Ag(DATC)}6{Ag(DAHC)}2](NO3)8 (4), and [{Ag(DATC}n](NO3)n (5), where the DAHC present in 4 is formed by in situ hydrolysis of the acid labile silyl ether group. The type of aggregate formed depends both upon the noncoordinating O-substituent of the ligand and the (also noncoordinating) counterion, with the normal preference of the ligand topology for forming Ag2L2 structures being broken by introduction of the bulky, lipophilic O-tert-butyldimethylsilyl (TBDMS) group. Of particular note is the octanuclear silver ring structure 4, which is isolated only when both the O-TBDMS group and the nitrate counteranion are present and is formed from four Ag2L2 dimers connected by Ag...Ag and hydrogen-bonding interactions. Diffusion rate measurement of this {Ag8} complex by 1H NMR (DOSY) indicates dissociation in CD3OD and CD3CN, showing that this supramolecular ring structure is formed upon crystallization, and establishing a qualitative limit to the strength of Ag...Ag interactions in solution. When solutions of the {Ag8} cluster in methanol are kept for several days though, a new UV-vis absorption is observed at around 430 nm, consistent with the formation of silver nanoparticles.

  4. Maine's Families: Poverty Despite Work.

    ERIC Educational Resources Information Center

    Lazere, Edward B.

    Children are among the poorest of Maine's residents. Nearly 1 in 5 children under the age of 18, 19.3%, lived in families below the federal poverty line in the early 1990s. Most of these poor children lived in working families. The working poor are often missing from policy debates, but their numbers are likely to increase with welfare reform…

  5. Maine's Approach to Global Education.

    ERIC Educational Resources Information Center

    Broyles, India L.; Krawic, Joanne

    This study of Maine schools inquires into efforts that have been made to internationalize the curriculum. Specifically, the researchers were interested in how curricular goals and organization contribute to an understanding of global society. The efforts to internationalize the curriculum upon which the researchers focused included the…

  6. Antidote: Civic Responsibility. Maine Law.

    ERIC Educational Resources Information Center

    Phi Alpha Delta Law Fraternity International, Washington, DC.

    Designed for middle school through high school students, this unit contains eight lesson plans that focus on Maine state law. The state lessons correspond to lessons in the volume, "Antidote: Civic Responsibility. Drug Avoidance Lessons for Middle School & High School Students." Developed to be presented by educators, law student, or…

  7. Left Main Coronary Artery Aneurysm

    PubMed Central

    Doustkami, Hossein; Maleki, Nasrollah; Tavosi, Zahra

    2016-01-01

    Aneurysms of the left main coronary artery are exceedingly rare clinical entities, encountered incidentally in approximately 0.1% of patients who undergo routine angiography. The most common cause of coronary artery aneurysms is atherosclerosis. Angiography is the gold standard for diagnosis and treatment. Depending on the severity of the coexisting coronary stenosis, patients with left main coronary artery aneurysms can be effectively managed either surgically or pharmacologically. We herein report a case of left main coronary artery aneurysm in a 72-year-old man with a prior history of hypertension presenting to our hospital because of unstable angina. The electrocardiogram showed ST-segment depression and T-wave inversion in the precordial leads. All the data of blood chemistry were normal. Echocardiography showed akinetic anterior wall, septum, and apex, mild mitral regurgitation and ejection fraction of 45%. Coronary angiography revealed a saccular aneurysm of the left main coronary artery with significant stenosis in the left anterior descending, left circumflex, and right coronary artery. The patient immediately underwent coronary artery bypass grafting and ligation of the aneurysm. At six months’ follow-up, he remained asymptomatic. PMID:27403190

  8. Fluorescent DNA-bound Ag nanoclusters

    NASA Astrophysics Data System (ADS)

    O'Neill, Patrick; Velazquez, Lourdes; Weirich, Kim; Fygenson, Deborah

    2009-03-01

    Few-atom fluorescent Ag nanoclusters self-assemble on short, synthetic DNA strands, and exhibit sequence and structure dependent fluorescence ranging from the blue to the near infrared. Here we report UV excitation as a ubiquitous feature of these emitters. Each emitter thus has two excitation peaks: a visible peak which is cluster-dependent, and a UV peak which has the same wavelength for all DNA-bound Ag clusters. This UV peak corresponds to resonant absorbance by the DNA bases, and produces the same emission spectra as visible excitation, suggesting energy transfer from the DNA bases to the Ag cluster. We make use of this UV excitation to image the emitters in unstained polyacrylamide gels, and show that electrophoresis can be used to create a pure solution of green DNA:Ag11 clusters from an inhomogeneous red solution of DNA:Ag>12 clusters.

  9. Direct electrospinning of Ag/polyvinylpyrrolidone nanocables

    NASA Astrophysics Data System (ADS)

    Song, Jie; Chen, Menglin; Olesen, Mikkel Buster; Wang, Chenxuan; Havelund, Rasmus; Li, Qiang; Xie, Erqing; Yang, Rong; Bøggild, Peter; Wang, Chen; Besenbacher, Flemming; Dong, Mingdong

    2011-12-01

    Core-sheath silver nanowire/polyvinylpyrrolidone (AgNW/PVP) nanocables have been fabricated via an efficient single-spinneret electrospinning method. The core-sheath structure is revealed by combining several characterization methods. A possible formation mechanism of the AgNW/PVP nanocable involving a strong stretching during the electrospinning process is proposed. Further, electrical measurements were performed on AgNW/PVP nanocables as well as bare AgNWs, which indicated the nanocables became insulating due to the isolation of highly conductive AgNWs by insulating PVP sheath. Therefore, the described fabrication method holds potential for the fabrication of low-cost metal/polymer composite materials for nanoelectronic applications in general.

  10. Anaplasmosis and ehrlichiosis - Maine, 2008.

    PubMed

    2009-09-25

    Anaplasmosis and ehrlichiosis are rickettsial tickborne diseases that have had at least a twofold increase in prevalence in the United States since 2000. Despite similar clinical presentations, the causative organisms are carried by different ticks with distinct geographic and ecologic associations. Surveillance efforts are complicated by ambiguous terminology and serologic testing with antibody cross-reactivity. Although anaplasmosis historically has been reported in Maine, ehrlichiosis has been reported infrequently. During 2007-2008, the number of physician-reported anaplasmosis cases nearly doubled in Maine, and ehrlichiosis cases increased more than fourfold. To examine this increase, the Maine Department of Health and Human Services (MDHHS) analyzed available data on tick burden and physician-reported cases of anaplasmosis and ehrlichiosis during 2000-2008. This report describes the results of that analysis, which indicated that Ixodes scapularis (the tick vector for Anaplasma phagocytophilum) was broadly distributed in Maine, whereas Amblyomma americanum (the tick vector for Erhlichia chaffeenisis) was scarce. Moreover, 95% of physician-reported ehrlichiosis cases lacked a concurrent serologic assessment to exclude anaplasmosis, suggesting that antibody cross-reactivity might have resulted in misclassification. In 2008, Maine modified case classification to enhance specificity; ehrlichiosis cases that lack a concurrent test for anaplasmosis are now classified as suspect rather than probable and therefore are not included in national surveillance summaries. The accuracy of case classification and surveillance can be improved by educating health-care providers regarding 1) the expected geographic distribution of tick vectors and 2) recommendations for confirmatory testing to distinguish between the causative organisms of anaplasmosis and ehrlichiosis.

  11. First-principles study of fcc-Ag/bcc-Fe interfaces

    NASA Astrophysics Data System (ADS)

    Lu, Song; Hu, Qing-Miao; Punkkinen, Marko P. J.; Johansson, Börje; Vitos, Levente

    2013-06-01

    Ab initio calculations are employed to determine the lower and upper bounds of the interfacial energy and work of separation of a fcc-Ag/bcc-Fe interface. The strain-free interfacial energy of the coherent interface is taken as the lower bound and the interfacial energy of the commensurate incoherent interface as the upper bound of the interfacial energy of a realistic semicoherent interface. The latter is estimated by applying an averaging scheme based on the interfacial energies obtained for the coherent interfaces. Similar calculations are performed for determining the bounds of the work of separation. We justify the use of the averaging scheme by carrying out large supercell calculations for a semicoherent interface. For a Fe(110)/Ag(111) semicoherent interface, we show that taking either Fe or Ag as the underlying lattice, our averaging scheme can yield a reasonable estimation of the work of separation of the semicoherent interface. However, when taking Ag as the underlying lattice, the averaged interfacial energy of the semicoherent interface is significantly underestimated due to the magnetism. The structure and magnetism at the coherent and semicoherent interfaces are discussed.

  12. Ab-Initio Determination of Novel Crystal Structures of the Thermoelectric Material MgAgSb

    SciTech Connect

    Kirkham, Melanie J; Moreira Dos Santos, Antonio F; Rawn, Claudia J; Lara-Curzio, Edgar; Sharp, Jeff W.; Thompson, Alan

    2012-01-01

    Materials with the half-Heusler structure possess interesting electrical and magnetic properties, including potential for thermoelectric applications. MgAgSb is compositionally and structurally related to many half-Heusler materials, but has not been extensively studied. This work presents the high-temperature X-ray diffraction analysis of MgAgSb between 27 and 420 C, complemented with thermoelectric property measurements. MgAgSb is found to exist in three different structures in this temperature region, taking the half-Heusler structure at high temperatures, a Cu2Sb-related structure at intermediate temperatures, and a previously unreported tetragonal structure at room temperature. All three structures are related by a distorted Mg-Sb rocksalt-type sublattice, differing primarily in the Ag location among the available tetrahedral sites. Transition temperatures between the three phases correlate well with discontinuities in the Seebeck coefficient and electrical conductivity; the best performance occurs with the novel room temperature phase. For application of MgAgSb as a thermoelectric material, it may be desirable to develop methods to stabilize the room temperature phase at higher temperatures.

  13. Possible charge disproportionation in 3R-AgNiO2 studied by neutron powder diffraction

    NASA Astrophysics Data System (ADS)

    Chung, J.-H.; Lim, J.-H.; Shin, Y. J.; Kang, J.-S.; Jaiswal-Nagar, D.; Kim, K. H.

    2008-12-01

    Using neutron-scattering techniques, we have investigated the nuclear and the magnetic structures of the triangular antiferromagnet 3R-AgNiO2 . The symmetry analysis based on the group theory suggests that the 3×3 charge order proposed for 2H-AgNiO2 [E. Wawrzyńska , Phys. Rev. Lett. 99, 157204 (2007)] will have a monoclinic symmetry if present in the trigonal lattice of 3R-AgNiO2 . The Rietveld refinement shows that symmetry reduction in the NiO2 layer is consistent with the prediction of the group theory. The pair density function consistently shows that the nearest-neighbor Ni-O bonds split into two groups separated by approximately 0.1Å . The antiferromagnetic Bragg peaks observed below TN=25K can be described by the propagation vector k=(0,1,0) of the monoclinic unit cell. The similarities of the local structure and the antiferromagnetic order strongly suggest that the novel charge order observed in 2H-AgNiO2 also exists in 3R-AgNiO2 .

  14. In vivo fluorescence imaging with Ag2S quantum dots in the second near-infrared region.

    PubMed

    Hong, Guosong; Robinson, Joshua T; Zhang, Yejun; Diao, Shuo; Antaris, Alexander L; Wang, Qiangbin; Dai, Hongjie

    2012-09-24

    Hits the dot: Ag(2)S quantum dots (QDs) with bright near-infrared-II fluorescence emission (around 1200 nm) and six-arm branched PEG surface coating were synthesized for in vivo small-animal imaging. The 6PEG-Ag(2)S QDs afforded a tumor uptake of approximately 10 % injected dose/gram, owing to a long circulation half-life of approximately 4 h. Clearance of the injected 6PEG-Ag(2)S QDs occurs mainly through the biliary pathway in mice.

  15. Photo- and thermo-chemical transformation of AgCl and Ag2S in environmental matrices and its implication.

    PubMed

    Yin, Yongguang; Xu, Wei; Tan, Zhiqiang; Li, Yanbin; Wang, Weidong; Guo, Xiaoru; Yu, Sujuan; Liu, Jingfu; Jiang, Guibin

    2017-01-01

    AgCl and Ag2S prevalently exist in the environment as minerals and/or the chlorination and sulfidation products of ionic silver and elemental silver nanoparticles (AgNPs). In this work, we investigated the chemical transformation of AgCl and Ag2S under simulated sunlight (in water) and incineration (in sludge and simulated municipal solid waste, SMSW). In the presence of natural organic matter, AgCl in river water was observed to be transformed into AgNPs under simulated sunlight, while photo-reduction of Ag2S could not take place under the same experimental conditions. During the course of incineration, pure Ag2S was transformed into elemental silver while AgCl remained stable; however, both Ag2S in sludge and AgCl in SMSW can be transformed to elemental silver under incineration, evident by the results of X-ray absorption spectroscopy and scanning electron microscopy measurements. Incineration temperature played an important role in the transformation of Ag2S and AgCl into elemental silver. These results suggest that chemical transformations of Ag2S and AgCl into elemental silver could be a possible source of naturally occurring or unintentionally produced AgNPs, affecting the fate, transport, bioavailability and toxicity of silver. Therefore, it is necessary to include the contributions of this transformation process when assessing the risk of ionic silver/AgNPs and the utilization and management of incineration residues.

  16. Magnetic testing

    NASA Technical Reports Server (NTRS)

    Pasley, R. L.; Barton, J. R.

    1973-01-01

    Magnetic techniques are described for the nondestructive evaluation of defects in materials. The physical principles, and the magnetic-particle method are discussed along with magnetic-hysteresis measurements and electric current perturbations.

  17. Silver(I) complexes of the weakly coordinating solvents SO(2) and CH(2)Cl(2): crystal structures, bonding, and energetics of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)].

    PubMed

    Decken, Andreas; Knapp, Carsten; Nikiforov, Grigori B; Passmore, Jack; Rautiainen, J Mikko; Wang, Xinping; Zeng, Xiaoqing

    2009-06-22

    Pushing the limits of coordination chemistry: The most weakly coordinated silver complexes of the very weakly coordinating solvents dichloromethane and liquid sulfur dioxide were prepared. Special techniques at low temperatures and the use of weakly coordinating anions allowed structural characterization of [Ag(OSO)][Al{OC(CF(3))(3)}(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(Cl(2)CH(2))(2)][SbF(6)] (see figure). An investigation of the bonding shows that these complexes are mainly stabilized by electrostatic monopole-dipole interactions.The synthetically useful solvent-free silver(I) salt Ag[Al(pftb)(4)] (pftb=--OC(CF(3))(3)) was prepared by metathesis reaction of Li[Al(pftb)(4)] with Ag[SbF(6)] in liquid SO(2). The solvated complexes [Ag(OSO)][Al(pftb)(4)], [Ag(OSO)(2/2)][SbF(6)], and [Ag(CH(2)Cl(2))(2)][SbF(6)] were prepared and isolated by special techniques at low temperatures and structurally characterized by single-crystal X-ray diffraction. The SO(2) complexes provide the first examples of coordination of the very weak Lewis base SO(2) to silver(I). The SO(2) molecule in [Ag(OSO)][Al(pftb)(4)] is eta(1)-O coordinated to Ag(+), while the SO(2) ligands in [Ag(OSO)(2/2)][SbF(6)] bridge two Ag(+) ions in an eta(2)-O,O' (trans,trans) manner. [Ag(CH(2)Cl(2))(2)][SbF(6)] contains [Ag(CH(2)Cl(2))(2)](+) ions linked through [SbF(6)](-) ions to give a polymeric structure. The solid-state silver(I) ion affinities (SIA) of SO(2) and CH(2)Cl(2), based on bond lengths and corresponding valence units in the corresponding complexes and tensimetric titrations of Ag[Al(pftb)(4)] and Ag[SbF(6)] with SO(2) vapor, show that SO(2) is a weaker ligand to Ag(+) than the commonly used weakly coordinating solvent CH(2)Cl(2) and indicated that binding strength of SO(2) to silver(I) in the silver(I) salts increases with increasing size of the corresponding counteranion ([Al(pftb)(4)](-)>[SbF(6)](-)). The experimental findings are in good agreement with theoretical gas-phase ligand

  18. Preparation and Properties of Double-Sided AgNWs/PVC/AgNWs Flexible Transparent Conductive Film by Dip-Coating Process.

    PubMed

    Chen, Cui-Yu; Jing, Mao-Xiang; Pi, Zhi-Chao; Zhu, Sheng-Wen; Shen, Xiang-Qian

    2015-12-01

    The double-sided transparent conductive films of AgNWs/PVC/AgNWs using the silver nanowires and PVC substrate were fabricated by the dip-coating process followed by mechanical press treatment. The morphological and structural characteristics were investigated by scanning electron microscope (SEM) and atomic force microscope (AFM), the photoelectric properties and mechanical stability were measured by ultraviolet-visible spectroscopy (UV-vis) spectrophotometer, four-point probe technique, 3M sticky tape test, and cyclic bending test. The results indicate that the structure and photoelectric performances of the AgNWs films were mainly affected by the dipping and lifting speeds. At the optimized dipping speed of 50 mm/min and lifting speed of 100 mm/min, the AgNWs are evenly distributed on the surface of the PVC substrate, and the sheet resistance of AgNWs film on both sides of PVC is about 60 Ω/sq, and the optical transmittance is 84.55 % with the figure of merit value up to 35.8. The film treated with the 10 MPa pressure shows excellent adhesion and low surface roughness of 17.8 nm and maintains its conductivity with the sheet resistance change of 17 % over 10,000 cyclic bends.

  19. Preparation and Properties of Double-Sided AgNWs/PVC/AgNWs Flexible Transparent Conductive Film by Dip-Coating Process

    NASA Astrophysics Data System (ADS)

    Chen, Cui-yu; Jing, Mao-xiang; Pi, Zhi-chao; Zhu, Sheng-wen; Shen, Xiang-qian

    2015-08-01

    The double-sided transparent conductive films of AgNWs/PVC/AgNWs using the silver nanowires and PVC substrate were fabricated by the dip-coating process followed by mechanical press treatment. The morphological and structural characteristics were investigated by scanning electron microscope (SEM) and atomic force microscope (AFM), the photoelectric properties and mechanical stability were measured by ultraviolet-visible spectroscopy (UV-vis) spectrophotometer, four-point probe technique, 3M sticky tape test, and cyclic bending test. The results indicate that the structure and photoelectric performances of the AgNWs films were mainly affected by the dipping and lifting speeds. At the optimized dipping speed of 50 mm/min and lifting speed of 100 mm/min, the AgNWs are evenly distributed on the surface of the PVC substrate, and the sheet resistance of AgNWs film on both sides of PVC is about 60 Ω/sq, and the optical transmittance is 84.55 % with the figure of merit value up to 35.8. The film treated with the 10 MPa pressure shows excellent adhesion and low surface roughness of 17.8 nm and maintains its conductivity with the sheet resistance change of 17 % over 10,000 cyclic bends.

  20. Antibacterial, antifungal, phytotoxic, and genotoxic properties of two complexes of Ag(I) with sulfachloropyridazine (SCP): X-ray diffraction of [Ag(SCP)]n.

    PubMed

    Mosconi, Natalia; Giulidori, Cecilia; Velluti, Francesca; Hure, Estela; Postigo, Agustina; Borthagaray, Graciela; Back, Davi Fernando; Torre, María H; Rizzotto, Marcela

    2014-06-01

    We report the synthesis, characterization, antibacterial and antifungal activities, phytotoxicity, and genotoxicity of two new complexes of silver(I) with sulfachloropyridazine (SCP), one of which is heteroleptic with SCP and SCN(-) ligands (Ag-SCP-SCN), the other of which is homoleptic (Ag-SCP); furthermore, the crystal structure of the homoleptic complex is disclosed. The heterocyclic N atom nearest to the Cl atom and the N(sulfonamide) atom could be coordination sites for the silver ion in the Ag-SCP-SCN complex. The Ag-SCP complex is a polymeric compound with metal-metal bonds, and the heterocyclic and sulfonamide N atoms are points of coordination for Ag(I) . Both complexes showed activity against all the tested bacteria, and in the cases of Escherichia coli and Pseudomonas aeruginosa, the action was better than that of SCP. In all cases, both silver-SCP complexes showed better antifungal activity than SCP, which was inactive against the tested fungi. Notably, the activity against P. aeruginosa, a nosocomial multidrug-resistant pathogen, was better than that of the reference antibiotic cefotaxim. Both silver-sulfa complexes displayed moderate activity against the tested yeast, especially for C. neoformans, which is an important fact considering the incidence of cryptococcosis, mainly in immune-deficient patients. No chromosomal aberrations were observed with the Allium cepa test, which is auspicious for further study of these complexes as potential drugs.

  1. Formation of AgGaS2 nano-pyramids from Ag2S nanospheres through intermediate Ag2S-AgGaS2 heterostructures and AgGaS2 sensitized Mn2+ emission.

    PubMed

    Huang, Feng; Zhou, Jiangcong; Xu, Ju; Wang, Yuansheng

    2014-02-21

    A one-pot solution synthesis of monodisperse AgGaS2 nanocrystals with uniform pyramid-like shape is realized for the first time, in which an interesting phase and shape evolution from monodisperse Ag2S nanospheres to pure AgGaS2 nano-pyramids through an intermediate stage of Ag2S-AgGaS2 heterostructures, is revealed. Evidently, upon introducing Mn(2+) ions into the reaction system, they are incorporated into AgGaS2 nano-pyramids which act as efficient sensitization matrixes for the red emission of Mn(2+) d-d transition under blue excitation. Benefiting from their non-toxicity and facile fabrication, Mn:AgGaS2 nanocrystals may find potential applications in some fields such as blue chip excited LEDs and bio-labeling.

  2. The Pangenome of the Anticarsia gemmatalis Multiple Nucleopolyhedrovirus (AgMNPV).

    PubMed

    Brito, Anderson Fernandes de; Braconi, Carla Torres; Weidmann, Manfred; Dilcher, Meik; Alves, João Marcelo Pereira; Gruber, Arthur; Zanotto, Paolo Marinho de Andrade

    2015-11-27

    The alphabaculovirus Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) is the world's most successful viral bioinsecticide. Through the 1980s and 1990s, this virus was extensively used for biological control of populations of Anticarsia gemmatalis (Velvetbean caterpillar) in soybean crops. During this period, genetic studies identified several variable loci in the AgMNPV; however, most of them were not characterized at the sequence level. In this study we report a full genome comparison among 17 wild-type isolates of AgMNPV. We found the pangenome of this virus to contain at least 167 hypothetical genes, 151 of which are shared by all genomes. The gene bro-a that might be involved in host specificity and carrying transporter is absent in some genomes, and new hypothetical genes were observed. Among these genes there is a unique rnf12-like gene, probably implicated in ubiquitination. Events of gene fission and fusion are common, as four genes have been observed as single or split open reading frames. Gains and losses of genomic fragments (from 20 to 900 bp) are observed within tandem repeats, such as in eight direct repeats and four homologous regions. Most AgMNPV genes present low nucleotide diversity, and variable genes are mainly located in a locus known to evolve through homologous recombination. The evolution of AgMNPV is mainly driven by small indels, substitutions, gain and loss of nucleotide stretches or entire coding sequences. These variations may cause relevant phenotypic alterations, which probably affect the infectivity of AgMNPV. This work provides novel information on genomic evolution of the AgMNPV in particular and of baculoviruses in general.

  3. The Pangenome of the Anticarsia gemmatalis Multiple Nucleopolyhedrovirus (AgMNPV)

    PubMed Central

    de Brito, Anderson Fernandes; Braconi, Carla Torres; Weidmann, Manfred; Dilcher, Meik; Alves, João Marcelo Pereira; Gruber, Arthur; Zanotto, Paolo Marinho de Andrade

    2016-01-01

    The alphabaculovirus Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) is the world’s most successful viral bioinsecticide. Through the 1980s and 1990s, this virus was extensively used for biological control of populations of Anticarsia gemmatalis (Velvetbean caterpillar) in soybean crops. During this period, genetic studies identified several variable loci in the AgMNPV; however, most of them were not characterized at the sequence level. In this study we report a full genome comparison among 17 wild-type isolates of AgMNPV. We found the pangenome of this virus to contain at least 167 hypothetical genes, 151 of which are shared by all genomes. The gene bro-a that might be involved in host specificity and carrying transporter is absent in some genomes, and new hypothetical genes were observed. Among these genes there is a unique rnf12-like gene, probably implicated in ubiquitination. Events of gene fission and fusion are common, as four genes have been observed as single or split open reading frames. Gains and losses of genomic fragments (from 20 to 900 bp) are observed within tandem repeats, such as in eight direct repeats and four homologous regions. Most AgMNPV genes present low nucleotide diversity, and variable genes are mainly located in a locus known to evolve through homologous recombination. The evolution of AgMNPV is mainly driven by small indels, substitutions, gain and loss of nucleotide stretches or entire coding sequences. These variations may cause relevant phenotypic alterations, which probably affect the infectivity of AgMNPV. This work provides novel information on genomic evolution of the AgMNPV in particular and of baculoviruses in general. PMID:26615220

  4. The visible light photocatalytic activity enhancement of cotton cellulose nanofibers/In2S3/Ag-CdS nanocomposites

    NASA Astrophysics Data System (ADS)

    Pan, Jiaqi; Li, Jing; Zhang, Xiufang; Zheng, Yingying; Cui, Can; Zhu, Zhiyan; Li, Chaorong

    2016-07-01

    Cotton cellulose nanofibers (CCNFs)/In2S3/Ag-CdS nanocomposites were prepared by a typical technical route which combined electrospinning and a chemical method. The results showed that the CCNFs/In2S3/Ag-CdS nanocomposites had a remarkable visible light photocatalytic property and cycling stability, which displayed a significant enhancement compared with that of pure In2S3. Through analysis, this enhancement could be mainly attributed to the multilevel structure of the composites.

  5. LSRA with Shuttle main gear

    NASA Technical Reports Server (NTRS)

    1993-01-01

    A space shuttle landing gear system is visible between the two main landing gear components on this NASA CV-990, modified as a Landing Systems Research Aircraft (LSRA). The space shuttle landing gear test unit, operated by a high-pressure hydraulic system, allowed engineers to assess and document the performance of space shuttle main and nose landing gear systems, tires and wheel assemblies, plus braking and nose wheel steering performance. The series of 155 test missions for the space shuttle program, conducted at NASA's Dryden Flight Research Center, Edwards, California, provided extensive data about the life and endurance of the shuttle tire systems and helped raise the shuttle crosswind landing limits at Kennedy.

  6. Heavy hydrocarbon main injector technology

    NASA Technical Reports Server (NTRS)

    Fisher, S. C.; Arbit, H. A.

    1988-01-01

    One of the key components of the Advanced Launch System (ALS) is a large liquid rocket, booster engine. To keep the overall vehicle size and cost down, this engine will probably use liquid oxygen (LOX) and a heavy hydrocarbon, such as RP-1, as propellants and operate at relatively high chamber pressures to increase overall performance. A technology program (Heavy Hydrocarbon Main Injector Technology) is being studied. The main objective of this effort is to develop a logic plan and supporting experimental data base to reduce the risk of developing a large scale (approximately 750,000 lb thrust), high performance main injector system. The overall approach and program plan, from initial analyses to large scale, two dimensional combustor design and test, and the current status of the program are discussed. Progress includes performance and stability analyses, cold flow tests of injector model, design and fabrication of subscale injectors and calorimeter combustors for performance, heat transfer, and dynamic stability tests, and preparation of hot fire test plans. Related, current, high pressure, LOX/RP-1 injector technology efforts are also briefly discussed.

  7. Neodymium Magnets.

    ERIC Educational Resources Information Center

    Wida, Sam

    1992-01-01

    Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)

  8. AgS2O6CF3: the first trifluoromethylsulfonylsulfate(VI).

    PubMed

    Malinowski, Przemysław J; Derzsi, Mariana; Grochala, Wojciech

    2013-08-07

    We describe the synthetic route towards a novel class of salts, trifluoromethylsulfonylsulfates, as exemplified by the silver(I) derivative (AgS2O6CF3). Formation proceeds via direct reaction between a triflate precursor, AgSO3CF3, and SO3. The title compound crystallizes in the P2(1)/c unit cell with a = 5.15746(14) Å, b = 25.8563(9) Å, c = 5.53970(14) Å and β = 101.1749(19)°. The structure is layered with the puckered [AgS2O6] 2D sheets; the terminal CF3 groups are separated by the van der Waals gap, as seen also for related metal triflates. The compound is very fragile thermally and it decomposes endothermally to AgSO3CF3 with concomitant evolution of SO3 even at 65 °C or upon grinding in an agate mortar; thus it may serve as a solid store of--otherwise volatile and corrosive--SO3. The IR and Raman spectra of AgS2O6CF3 have been tentatively assigned based on similarities to those of related Ag2S2O7 and AgSO3CF3 and phonon calculations. Synthesis and properties of KS2O6CF3 are also briefly described.

  9. On the measurement of /sup 107/Ag//sup 109/Ag ratios in meteorites

    SciTech Connect

    Kutschera, W.; Faestermann, T.; Gillitzer, A.; Fortuna, G.

    1986-01-01

    The detection of stable Ag isotopes in meteorites at the ppB level was attempted in an AMS experiment using the Munich MP tandem accelerator in conjunction with a time-of-flight detection system. The sensitivity of detecting Ag at this level was established by observing a counting rate of 17 ions of /sup 107/Ag per sec from a Au sample, which had been spiked with the radioisotope /sup 105/Ag (T/sub 1/2/ = 41 d) at a concentration of 1.0 ppB. A blank Ta sample gave no /sup 105/Ag counts in 13 min, which corresponds to a detection limit of 7.5 x 10/sup -5/ ppB. Although this sensitivity was clearly sufficient to perform /sup 107/Ag and /sup 109/Ag measurements in the desired concentration range, experiments with these isotopes were hampered by a currently irreducable background of stable Ag in the ppM range, possibly originating from the ion source itself. Indications of extraordinarily high Ag concentrations, far above this background, were observed in some of the investigated meteorites, but conclusions on their actual existence must await a better understanding of the origin of the general Ag background. 10 refs., 4 figs., 3 tabs.

  10. Study of antibacterial activity of Ag and Ag2CO3 nanoparticles stabilized over montmorillonite

    NASA Astrophysics Data System (ADS)

    Sohrabnezhad, Sh.; Pourahmad, A.; Mehdipour Moghaddam, M. J.; Sadeghi, A.

    2015-02-01

    Silver carbonate and silver nanoparticles (NPs) over of stabilizer montmorillonite (MMT) have been synthesized in aqueous and polyol solvent, respectively. Dispersions of silver nanoparticles have been prepared by the reduction of silver nitrate over of MMT in presence and absence of Na2CO3 compound in ethylene glycol. It was observed that montmorillonite was capable of stabilizing formed Ag nanoparticles through the reduction of Ag+ ions in ethylene glycol. Na2CO3 was used as carbonate source in synthesis of Ag2CO3 NPs in water solvent and also for controlling of Ag nanoparticles size in ethylene glycol medium. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (DRS). The TEM images showed that Ag NPs size in presence Na2CO3 salts was smaller than without that. The results indicated intercalation of Ag and Ag2CO3 nanoparticles into the montmorillonite clay layers. The diffuse reflectance spectra exhibited a strong surface plasmon resonance (SPR) adsorption peak in the visible region, resulting from Ag nanoparticles. The antibacterial testing results showed that the Ag2CO3-MMT nanocomposite exhibited an antibacterial activity higher than Ag-MMT sample against Escherichia coli.

  11. Observation of New Isotope 131Ag via the Two-Step Fragmentation Technique

    NASA Astrophysics Data System (ADS)

    Wang, He; Aoi, N.; Takeuchi, S.; Matsushita, M.; Doornenbal, P.; Motobayashi, T.; Steppenbeck, D.; Yoneda, K.; Kobayashi, K.; J., Lee; Liu, Hong-Na; Kondo, Y.; Yokoyama, R.; Sakurai, H.; Ye, Yan-Lin

    2013-04-01

    We report on the first observation of the neutron-rich nucleus 131Ag. This isotope was produced via fragmentation reactions of intense secondary radioactive ion beams, including 134,135Sn. The secondary beams were produced from induced fission reactions from a stable 238U beam at 345 MeV/nucleon. Secondary reaction residues were selected by the ZeroDegree spectrometer and identified by measuring their magnetic rigidity, time of flight, energy loss, and total kinetic energy.

  12. Electrodeposited Ag-Stabilization Layer for High Temperature Superconducting Coated Conductors: Preprint

    SciTech Connect

    Bhattacharya, R. N.; Mann, J.; Qiao, Y.; Zhang, Y.; Selvamanickam, V.

    2010-11-01

    We developed a non-aqueous based electrodepostion process of Ag-stabilization layer on YBCO superconductor tapes. The non-aqueous electroplating solution is non-reactive to the HTS layer thus does not detoriate the critical current capability of the superconductor layer when plated directly on the HTS tape. The superconducting current capabilities of these tapes were measured by non-contact magnetic measurements.

  13. Fabrication of magnetic nanodot arrays for patterned magnetic recording media.

    PubMed

    Sato, Hirotaka; Homma, Takayuki

    2007-01-01

    Fabrication processes of arrayed magnetic nanodots for the use of patterned magnetic recording media were reviewed. One candidate for the patterned media is ordered assemble of magnetic nanoparticles, and the other is patterned magnetic thin films fabricated using various micro/nano scale machining processes. For the formation of patterned masks and molds, lithography processes as well as self-organized pattern formation are utilized. For the deposition processes of magnetic dots, electrochemical deposition processes were widely used. These fabrication processes are reviewed mainly from recent reports. The recording systems for the patterned media including probe-type-recording are also overviewed.

  14. Spin glass in semiconducting KFe1.05Ag0.88Te2 single crystals

    SciTech Connect

    Ryu, H.; Lei, H.; Klobes, B.; Warren, J. B.; Hermann, R. P.; Petrovic, C.

    2015-05-26

    We report discovery of KFe1.05Ag0.88Te2 single crystals with semiconducting spin glass ground state. Composition and structure analysis suggest nearly stoichiometric I4/mmm space group but allow for the existence of vacancies, absent in long range semiconducting antiferromagnet KFe1.05Ag0.88Te2. The subtle change in stoichometry in Fe/Ag sublattice changes magnetic ground state but not conductivity, giving further insight into the semiconducting gap mechanism.

  15. Hierarchically plasmonic photocatalysts of Ag/AgCl nanocrystals coupled with single-crystalline WO3 nanoplates

    NASA Astrophysics Data System (ADS)

    Chen, Deliang; Li, Tao; Chen, Qianqian; Gao, Jiabing; Fan, Bingbing; Li, Jian; Li, Xinjian; Zhang, Rui; Sun, Jing; Gao, Lian

    2012-08-01

    The hierarchical photocatalysts of Ag/AgCl@plate-WO3 have been synthesized by anchoring Ag/AgCl nanocrystals on the surfaces of single-crystalline WO3 nanoplates that were obtained via an intercalation and topochemical approach. The heterogeneous precipitation process of the PVP-Ag+-WO3 suspensions with a Cl- solution added drop-wise was developed to synthesize AgCl@WO3 composites, which were then photoreduced to form Ag/AgCl@WO3 nanostructures in situ. WO3 nanocrystals with various shapes (i.e., nanoplates, nanorods, and nanoparticles) were used as the substrates to synthesize Ag/AgCl@WO3 photocatalysts, and the effects of the WO3 contents and photoreduction times on their visible-light-driven photocatalytic performance were investigated. The techniques of TEM, SEM, XPS, EDS, XRD, N2 adsorption-desorption and UV-vis DR spectra were used to characterize the compositions, phases and microstructures of the samples. The RhB aqueous solutions were used as the model system to estimate the photocatalytic performance of the as-obtained Ag/AgCl@WO3 nanostructures under visible light (λ >= 420 nm) and sunlight. The results indicated that the hierarchical Ag/AgCl@plate-WO3 photocatalyst has a higher photodegradation rate than Ag/AgCl, AgCl, AgCl@WO3 and TiO2 (P25). The contents and morphologies of the WO3 substrates in the Ag/AgCl@plate-WO3 photocatalysts have important effects on their photocatalytic performance. The related mechanisms for the enhancement in visible-light-driven photodegradation of RhB molecules were analyzed.The hierarchical photocatalysts of Ag/AgCl@plate-WO3 have been synthesized by anchoring Ag/AgCl nanocrystals on the surfaces of single-crystalline WO3 nanoplates that were obtained via an intercalation and topochemical approach. The heterogeneous precipitation process of the PVP-Ag+-WO3 suspensions with a Cl- solution added drop-wise was developed to synthesize AgCl@WO3 composites, which were then photoreduced to form Ag/AgCl@WO3 nanostructures in

  16. The characteristics of novel bimodal Ag-TiO2 nanoparticles generated by hybrid laser-ultrasonic technique

    NASA Astrophysics Data System (ADS)

    Hamad, Abubaker; Li, Lin; Liu, Zhu; Zhong, Xiang Li; Burke, Grace; Wang, Tao

    2016-04-01

    Silver-titania (Ag-TiO2) nanoparticles with smaller Ag nanoparticles attached to larger TiO2 nanoparticles were generated by hybrid ultrasonic vibration and picosecond laser ablation of Ag and Ti bulk targets in deionised water, for the first time. The laser has a wavelength of 1064 nm and a pulse duration of 10 ps. It was observed that without the ultrasonic vibration, Ag and TiO2 nanoparticles did not combine, thus the role of ultrasonic vibration is essential. In addition, colloidal TiO2 and Ag nanoparticles were generated separately for comparison under the same laser beam characteristics and process conditions. The absorption spectra of colloidal Ag-TiO2 cluster nanoparticles were examined by UV-Vis spectroscopy, and size distribution was characterised using transmission electron microscopy. The morphology and composition of Ag-TiO2 nanoparticles were examined using scanning transmission electron microscopy in high-angle annular dark field, and energy-dispersive X-ray spectroscopy. The crystalline structures were investigated by X-ray diffraction. The size of larger TiO2 particles was in the range 30-150 nm, and the smaller-sized Ag nanoparticles attached to the TiO2 was mainly in the range of 10-15 nm. The yield is more than 50 % with the remaining nanoparticles in the form of uncombined Ag and TiO2. The nanoparticles generated had strong antibacterial effects as tested against E. coli. A discussion is given on the role of ultrasonic vibration in the formation of Ag-TiO2 hybrid nanoparticles by picosecond laser ablation.

  17. Thermodynamic properties of the specific binding between Ag+ ions and C:C mismatched base pairs in duplex DNA.

    PubMed

    Torigoe, Hidetaka; Miyakawa, Yukako; Ono, Akira; Kozasa, Tetsuo

    2011-02-01

    Metal-mediated base pairs formed by the interaction between metal ions and artificial bases in oligonucleotides have been developed for potential applications in nanotechnology. We recently found that a natural C:C mismatched base pair bound to an Ag(+) ion to generate a novel metal-mediated base pair in duplex DNA. Preparation of the novel C-Ag-C base pair involving natural bases is more convenient than that of metal-mediated base pairs involving artificial bases because time-consuming base synthesis is not required. Here, we examined the thermodynamic properties of the binding between the Ag(+) ion and each of single and double C:C mismatched base pair in duplex DNA by isothermal titration calorimetry. The Ag(+) ion specifically bound to the C:C mismatched base pair at a 1:1 molar ratio with 10(6) M(-1) binding constant, which was significantly larger than those for nonspecific metal ion-DNA interactions. The specific binding between the Ag(+) ion and the single C:C mismatched base pair was mainly driven by the positive dehydration entropy change and the negative binding enthalpy change. In the interaction between the Ag(+) ion and each of the consecutive and interrupted double C:C mismatched base pairs, stoichiometric binding at a 1:1 molar ratio was achieved in each step of the first and second Ag(+) binding. The binding affinity for the second Ag(+) binding was similar to that for the first Ag(+) binding. Stoichiometric binding without interference and negative cooperativity may be favorable for aligning multiple Ag(+) ions in duplex DNA for applications of the metal-mediated base pairs in nanotechnology.

  18. Highly Efficient Antibacterial and Pb(II) Removal Effects of Ag-CoFe2O4-GO Nanocomposite.

    PubMed

    Ma, Shuanglong; Zhan, Sihui; Jia, Yanan; Zhou, Qixing

    2015-05-20

    Ag-CoFe2O4-graphene oxide (Ag-CoFe2O4-GO) nanocomposite was synthesized by doping silver and CoFe2O4 nanoparticles on the surface of GO, which was used to purify both bacteria and Pb(II) contaminated water. The Ag-CoFe2O4-GO nanomaterial was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), cyclic voltammetry (CV), and magnetic property tests. It can be found that Ag-CoFe2O4-GO nanocomposite exhibited excellent antibacterial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus compared with CoFe2O4, Ag-CoFe2O4, and CoFe2O4-GO composite. This superior disinfecting effect was possibly attributed to the combination of GO nanosheets and Ag nanoparticles. Several antibacterial factors including temperature, time, and pH were also investigated. It was obvious that E. coli was more susceptible than S. aureus toward all the four types of nanomaterials. The structural difference of bacterial membranes should be responsible for the resistant discrepancy. We also found that Ag-CoFe2O4-GO inactivated both bacteria in an irreversibly stronger manner than Ag-CoFe2O4 and CoFe2O4-GO. The Pb(II) removal efficiency with all the nanomaterials showed significant dependence on the surface area and zeta potential of the materials. In this work, not only did we demonstrate the simultaneous superior removal efficiency of bacteria and Pb(II) by Ag-CoFe2O4-GO but also the antibacterial mechanism was discussed to have a better understanding of the interaction between Ag-CoFe2O4-GO and bacteria. In a word, taking into consideration the easy magnetic separation, bulk availability, and irreversibly high antibacterial activity of Ag-CoFe2O4-GO, it is the very promising candidate material for advanced antimicrobial or Pb(II) contaminated water treatment.

  19. Easily separated silver nanoparticle-decorated magnetic graphene oxide: Synthesis and high antibacterial activity.

    PubMed

    Zhang, Huai-Zhi; Zhang, Chang; Zeng, Guang-Ming; Gong, Ji-Lai; Ou, Xiao-Ming; Huan, Shuang-Yan

    2016-06-01

    Silver nanoparticle-decorated magnetic graphene oxide (MGO-Ag) was synthesized by doping silver and Fe3O4 nanoparticles on the surface of GO, which was used as an antibacterial agent. MGO-Ag was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy dispersive X-ray (EDS), X-ray diffraction (XRD), Raman spectroscopy and magnetic property tests. It can be found that magnetic iron oxide nanoparticles and nano-Ag was well dispersed on graphene oxide; and MGO-Ag exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus. Several factors were investigated to study the antibacterial effect of MGO-Ag, such as temperature, time, pH and bacterial concentration. We also found that MGO-Ag maintained high inactivation rates after use six times and can be separated easily after antibacterial process. Moreover, the antibacterial mechanism is discussed and the synergistic effect of GO, Fe3O4 nanoparticles and nano-Ag accounted for high inactivation of MGO-Ag.

  20. YNPS main coolant system decontamination

    SciTech Connect

    Metcalf, E.T.

    1996-12-31

    The Yankee Nuclear Power Station (YNPS) located in Rowe, Massachusetts, is a four-loop pressurized water reactor that permanently ceased power operation on February 26, 1992. Decommissioning activities, including steam generator removal, reactor internals removal, and system dismantlement, have been in progress since the shutdown. One of the most significant challenges for YNPS in 1996 was the performance of the main coolant system chemical decontamination. This paper describes the objectives, challenges, and achievements involved in the planning and implementation of the chemical decontamination.

  1. Magnetically responsive dry fluids

    NASA Astrophysics Data System (ADS)

    Sousa, Filipa L.; Bustamante, Rodney; Millán, Angel; Palacio, Fernando; Trindade, Tito; Silva, Nuno J. O.

    2013-07-01

    Ferrofluids and dry magnetic particles are two separate classes of magnetic materials with specific niche applications, mainly due to their distinct viscosity and interparticle distances. For practical applications, the stability of these two properties is highly desirable but hard to achieve. Conceptually, a possible solution to this problem would be encapsulating the magnetic particles but keeping them free to rotate inside a capsule with constant interparticle distances and thus shielded from changes in the viscosity of the surrounding media. Here we present an example of such materials by the encapsulation of magnetic ferrofluids into highly hydrophobic silica, leading to the formation of dry ferrofluids, i.e., a material behaving macroscopically as a dry powder but locally as a ferrofluid where magnetic nanoparticles are free to rotate in the liquid.Ferrofluids and dry magnetic particles are two separate classes of magnetic materials with specific niche applications, mainly due to their distinct viscosity and interparticle distances. For practical applications, the stability of these two properties is highly desirable but hard to achieve. Conceptually, a possible solution to this problem would be encapsulating the magnetic particles but keeping them free to rotate inside a capsule with constant interparticle distances and thus shielded from changes in the viscosity of the surrounding media. Here we present an example of such materials by the encapsulation of magnetic ferrofluids into highly hydrophobic silica, leading to the formation of dry ferrofluids, i.e., a material behaving macroscopically as a dry powder but locally as a ferrofluid where magnetic nanoparticles are free to rotate in the liquid. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01784b

  2. Agent planning in AgScala

    NASA Astrophysics Data System (ADS)

    Tošić, Saša; Mitrović, Dejan; Ivanović, Mirjana

    2013-10-01

    Agent-oriented programming languages are designed to simplify the development of software agents, especially those that exhibit complex, intelligent behavior. This paper presents recent improvements of AgScala, an agent-oriented programming language based on Scala. AgScala includes declarative constructs for managing beliefs, actions and goals of intelligent agents. Combined with object-oriented and functional programming paradigms offered by Scala, it aims to be an efficient framework for developing both purely reactive, and more complex, deliberate agents. Instead of the Prolog back-end used initially, the new version of AgScala relies on Agent Planning Package, a more advanced system for automated planning and reasoning.

  3. SPIN MATCHING FROM AGS TO RHIC.

    SciTech Connect

    MACKAY,W.W.; TSOUPAS,N.

    2002-11-06

    With a partial Siberian snake in the AGS and transport lines with interspersed horizontal and vertical bends, the incoming spin direction at the injection points of both the collider rings is not likely to match the ideal vertical stable spin direction of RHIC which has two full helical Siberian snakes per ring. In this paper we examine the matching of a polarized beam transferred from the AGS into RHIC. The present 5% partial solenoidal snake as well as a proposed 20% superconducting helical are considered for the AGS. Solutions with retuned snakes in RHIC to better match the incoming beam have been found.

  4. OVERVIEW OF THE AGS COLD SNAKE POWER SUPPLIES AND THE NEW RHIC SEXTUPOLE POWER SUPPLIES

    SciTech Connect

    BRUNO,D.; GANETIS, G.; SANDBERG, J.; LOUIE, W.

    2007-06-25

    The two rings in the Relativistic Heavy Ion Collider (RHIC) were originally constructed with 24 sextupole power supplies, 12 for each ring. Before the start of Run 7, 24 new sextupole power supplies were installed, 12 for each ring. Individual sextupole power supplies are now each connected to six sextupole magnets. A superconducting snake magnet and power supplies were installed in the Alternating Gradient Synchrotron (AGS) and commissioned during RHIC Run 5, and used operationally in RHIC Run 6. The power supply technology, connections, control systems and interfacing with the Quench Protection system for both these systems will be presented.

  5. Ozone decomposition on Ag/SiO2 and Ag/clinoptilolite catalysts at ambient temperature.

    PubMed

    Nikolov, Penko; Genov, Krassimir; Konova, Petya; Milenova, Katya; Batakliev, Todor; Georgiev, Vladimir; Kumar, Narendra; Sarker, Dipak K; Pishev, Dimitar; Rakovsky, Slavcho

    2010-12-15

    Silver modified zeolite (Bulgarian natural clinoptilolite) and Ag/silica catalysts were synthesized by ion exchange and incipient wet impregnation method respectively and characterized by different techniques. DC arc-AES was used for Ag detection. XRD spectra show that Ag is loaded over the surface of the SiO(2) sample and that after the ion-exchange process the HEU type structure of clinoptilolite is retained. UV-VIS (specific reflection at 310 nm) and IR (band at 695 cm(-1)) spectroscopy analysis proved that silver is loaded as a T-atom into zeolite channels as Ag(+), instead of Na(+), Ca(2+), or K(+) ions, existing in the natural clinoptilolite form. The samples Ag/SiO(2) and Ag-clinoptilolite were tested as catalysts for decomposition of gas phase ozone. Very high catalytic activity (up to 99%) was observed and at the same time the catalysts remained active over time at room temperature.

  6. Magnetic Levitation.

    ERIC Educational Resources Information Center

    Rossing, Thomas D.; Hull, John R.

    1991-01-01

    Discusses the principles of magnetic levitation presented in the physics classroom and applied to transportation systems. Topics discussed include three classroom demonstrations to illustrate magnetic levitation, the concept of eddy currents, lift and drag forces on a moving magnet, magnetic levitation vehicles, levitation with permanent magnets…

  7. Magnetic Spinner

    ERIC Educational Resources Information Center

    Ouseph, P. J.

    2006-01-01

    A science toy sometimes called the "magnetic spinner" is an interesting class demonstration to illustrate the principles of magnetic levitation. It can also be used to demonstrate Faraday's law and a horizontally suspended physical pendulum. The levitated part contains two circular magnets encased in a plastic housing. Each magnet stays…

  8. Binary interactions with high accretion rates onto main sequence stars

    NASA Astrophysics Data System (ADS)

    Shiber, Sagiv; Schreier, Ron; Soker, Noam

    2016-07-01

    Energetic outflows from main sequence stars accreting mass at very high rates might account for the powering of some eruptive objects, such as merging main sequence stars, major eruptions of luminous blue variables, e.g., the Great Eruption of Eta Carinae, and other intermediate luminosity optical transients (ILOTs; red novae; red transients). These powerful outflows could potentially also supply the extra energy required in the common envelope process and in the grazing envelope evolution of binary systems. We propose that a massive outflow/jets mediated by magnetic fields might remove energy and angular momentum from the accretion disk to allow such high accretion rate flows. By examining the possible activity of the magnetic fields of accretion disks, we conclude that indeed main sequence stars might accrete mass at very high rates, up to ≈ 10-2 M ⊙ yr-1 for solar type stars, and up to ≈ 1 M ⊙ yr-1 for very massive stars. We speculate that magnetic fields amplified in such extreme conditions might lead to the formation of massive bipolar outflows that can remove most of the disk's energy and angular momentum. It is this energy and angular momentum removal that allows the very high mass accretion rate onto main sequence stars.

  9. Space shuttle main engine controller

    NASA Technical Reports Server (NTRS)

    Mattox, R. M.; White, J. B.

    1981-01-01

    A technical description of the space shuttle main engine controller, which provides engine checkout prior to launch, engine control and monitoring during launch, and engine safety and monitoring in orbit, is presented. Each of the major controller subassemblies, the central processing unit, the computer interface electronics, the input electronics, the output electronics, and the power supplies are described and discussed in detail along with engine and orbiter interfaces and operational requirements. The controller represents a unique application of digital concepts, techniques, and technology in monitoring, managing, and controlling a high performance rocket engine propulsion system. The operational requirements placed on the controller, the extremely harsh operating environment to which it is exposed, and the reliability demanded, result in the most complex and rugged digital system ever designed, fabricated, and flown.

  10. The Main Aeromonas Pathogenic Factors

    PubMed Central

    Tomás, J. M.

    2012-01-01

    The members of the Aeromonas genus are ubiquitous, water-borne bacteria. They have been isolated from marine waters, rivers, lakes, swamps, sediments, chlorine water, water distribution systems, drinking water and residual waters; different types of food, such as meat, fish, seafood, vegetables, and processed foods. Aeromonas strains are predominantly pathogenic to poikilothermic animals, and the mesophilic strains are emerging as important pathogens in humans, causing a variety of extraintestinal and systemic infections as well as gastrointestinal infections. The most commonly described disease caused by Aeromonas is the gastroenteritis; however, no adequate animal model is available to reproduce this illness caused by Aeromonas. The main pathogenic factors associated with Aeromonas are: surface polysaccharides (capsule, lipopolysaccharide, and glucan), S-layers, iron-binding systems, exotoxins and extracellular enzymes, secretion systems, fimbriae and other nonfilamentous adhesins, motility and flagella. PMID:23724321

  11. STS-3 main parachute failure

    NASA Technical Reports Server (NTRS)

    Runkle, R.; Henson, K.

    1982-01-01

    A failure analysis of the parachute on the Space Transportation System 3 flight's solid rocket booster's is presented. During the reentry phase of the two Solid Rocket Boosters (SRBs), one 115 ft diameter main parachute failed on the right hand SRB (A12). This parachute failure caused the SRB to impact the Ocean at 110 ft/sec in lieu of the expected 3 parachute impact velocity of 88 ft/sec. This higher impact velocity relates directly to more SRB aft skirt and more motor case damage. The cause of the parachute failure, the potential risks of losing an SRB as a result of this failure, and recommendations to ensure that the probability of chute failures of this type in the future will be low are discussed.

  12. Effects of Ag on the Kirkendall void formation of Sn-xAg/Cu solder joints

    NASA Astrophysics Data System (ADS)

    Kim, Sunghwan; Yu, Jin

    2010-10-01

    Binary Sn-Ag solders with varying amounts of Ag (0.5, 2.0, and 3.5 wt %) were reacted with Cu under bump metallurgy (UBM) which was electroplated with bis-sodium sulfopropyl-disulfide additive, and the characteristics of Kirkendall void formation at the solder joints were investigated. The results indicate that the propensity to form Kirkendall voids at the solder joint decreased with the Ag content. Subsequent Auger electron spectroscopy analyses showed that Ag dissolved in the Cu UBM reduced the segregation of S to the Cu3Sn/Cu interface, which suppressed the nucleation of Kirkendall voids at the interface.

  13. Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

    2011-07-01

    Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

  14. Distribution of Ag in Cu-sulfides in Kupferschiefer deposit, SW Poland

    NASA Astrophysics Data System (ADS)

    Kozub, Gabriela A.

    2014-05-01

    The Cu-Ag Kupferschiefer deposit located at the Fore-Sudetic Monocline (SW Poland) is a world class deposit of stratabound type. The Cu-Ag mineralization in the deposit occurs in the Permian sedimentary rocks (Rotliegend and Zechstein) in three lithological types of ore: the dolomite, the black shale and the sandstone. Silver, next to copper, is the most important element in the Kupferschiefer deposit (Salamon 1979; Piestrzyński 2007; Pieczonka 2011). Although occurrence of the Ag-minerals such as native silver, silver amalgams, stromeyerite, jalpaite and mckinstryite, silver is mainly present in the deposit due to isomorphic substitutions in Cu-minerals such as chalcocite, bornite, tennantite, covellite and chalcopyrite. The aim of the study was to define distribution of silver in Cu-minerals and correlate occurrence of Ag-enriched Cu-sulfides with native silver and silver amalgams. Identification of minerals and textural observation were performed using field emission scanning electron microscope. Analyzes of chemical composition of Cu-sulfides were performed utilizing electron microprobe. Silver concentration in Cu sulfides ranges from 0.1 to 10.4 wt.% in chalcocite, 0.2-15.8 wt.% in bornite, 0.1-2.9 wt.% in tennantite, 0.05-0.3 wt.% in chalcopyrite and ca. 0.4 wt.% in covellite. In general, distribution of silver in Cu-minerals is irregular, as indicated by high variations of Ag concentration in each mineral. Content of Ag in Cu-sulphides, in samples where native silver and silver amalgams are not found, is lower than in samples, where native silver and silver amalgams are noted. The chemical analyzes of Ag-bearing Cu-minerals indicate decrease of Cu content in minerals with high Ag concentration. In such case, decrease of Fe content is also noted in bornite. Lack of micro-inclusions of the native silver or silver amalgams in the Cu-minerals indicates that presence of Ag is mainly related to the isomorphic substitutions. This is in agreement with previous

  15. Measurement of the magnetic field coefficients of particle accelerator magnets

    SciTech Connect

    Herrera, J.; Ganetis, G.; Hogue, R.; Rogers, E.; Wanderer, P.; Willen, E.

    1989-01-01

    An important aspect in the development of magnets to be used in particle accelerators is the measurement of the magnetic field in the beam aperture. In general it is necessary to measure the harmonic multipoles in the dipole, quadrupole, and sextupole magnets for a series of stationary currents (plateaus). This is the case for the Superconducting Super Collider (SSC) which will be ramped to high field over a long period (/approximately/1000 sec.) and then remain on the flat top for the duration of the particle collision phase. In contrast to this mode of operation, the Booster ring being constructed for the Brookhaven AGS, will have a fast ramp rate of approximately 10 Hz. The multipole fields for these Booster magnets must therefore be determined ''on the ramp.'' In this way the effect of eddy currents will be taken into account. The measurement system which we will describe in this paper is an outgrowth of that used for the SSC dipoles. It has the capability of measuring the field multipoles on both a plateau or during a fast ramp. In addition, the same basic coil assembly is used to obtain the magnetic multipoles in dipole, quadrupole, and sextupole magnets. 2 refs., 3 figs., 1 tab.

  16. Lesson 3: Attorney General (AG) Certification

    EPA Pesticide Factsheets

    The AG Certification is a letter confirming legal authority to implement the electronic reporting covered by the application and enforce the affected programs using the electronic documents received under those programs.

  17. Autocatalytic synthesis of multifunctional precursors for fabricating silica microspheres with well-dispersed Ag and Co3O4 nanoparticles.

    PubMed

    Xu, Linxu; Cui, Fang; Zhang, Jiajia; Hao, Yanjun; Wang, Yan; Cui, Tieyu

    2017-01-05

    Herein, an autocatalytic route to fabricate dual metal ion-equipped organic/inorganic hybrid silica, an ideal precursor for multifunctional silica-based composites integrated with well-dispersed Ag and Co3O4 nanoparticles was demonstrated. Significantly, by rational selection of reactants, such dual metal ion-equipped organic/inorganic hybrid silica can be synthesized through successive spontaneous reactions under near neutral conditions without an additional catalyst. Both the Ag(+) and Co(2+) ions are introduced into silica by chemical bonds, which favor the formation of small-sized and well-dispersed Ag and Co3O4 nanoparticles without aggregation in the entire silica matrix. After calcination, multifunctional silica composites equipped with well-dispersed Ag and Co3O4 nanoparticles were obtained. The as-obtained silica composites, as indicated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), have a spherical morphology and smooth surface. TEM tests also reveal the well dispersed fashion of Ag and Co3O4 nanoparticles. In addition, the obtained Ag-Co3O4@SiO2 composites exhibit good catalytic performance in the reduction of methylene blue (MB) with NaBH4 as a reducing agent, and can be readily recycled by an external magnetic field due to their superparamagnetic properties.

  18. Fabrication of TiO2/Ag2O heterostructure with enhanced photocatalytic and antibacterial activities under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Bingkun; Mu, Lilong; Han, Bing; Zhang, Jingtao; Shi, Hengzhen

    2017-02-01

    TiO2/Ag2O heterostructure prepared by a facile in situ precipitation route was used as an effective visible light-driven photocatalyst for degradation of methylene blue (MB) and inactivation of E. coli. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) revealed that Ag2O nanoparticles were well distributed on the surface of TiO2 microspheres. The TiO2/Ag2O composite with optimal mass ratio of TiO2 and Ag2O displayed extremely good photodegradation ability and antibacterial capability under visible light irradiation, which was mainly ascribed to the synergistic effect between Ag2O and TiO2, including highly dispersed smaller Ag2O particles, increased visible light absorption and efficient separation of photo-induced charge carriers. Meanwhile, the roles of the radical species in the photocatalysis process were investigated. Our results showed that the TiO2/Ag2O could be used as a dual functional material in water treatment of removing the organic pollutant and killing the bacterium at the same time.

  19. Promotion of Ag/H-BEA by Mn for lean NO reduction with propane at low temperature.

    PubMed

    Pan, Hua; Su, Qingfa; Chen, Jie; Ye, Qing; Liu, Yiting; Shi, Yao

    2009-12-15

    Effects of adding manganese to Ag/H-BEA for selective catalytic reduction of NO(x) with propane (C(3)H(8)-SCR) were investigated under a lean-burn condition. Mn addition significantly promotes the catalytic performance of Ag/H-BEA below 673 K. A Ag-Mn/H-BEA catalyst with equal metal weight of 3 wt % has the highest activity for C(3)H(8)-SCR among samples with a different bimetal loading. Manganese is mainly present in the 3+ and 4+ oxidation states in Ag-Mn/H-BEA catalysts. The major contributions of manganese suggested by the data presented in this paper are to catalyze the NO oxidation and stabilize silver in a dispersed Ag(+) state. The presence of silver enforces the transformation of a certain amount of Mn(3+) ions to Mn(4+) ions. The activity of Ag-Mn/H-BEA decreases slightly at low SO(2) concentrations (0-200 ppm) but decreases significantly at high SO(2) concentrations (400-800 ppm). In the presence of 10% H(2)O and 200 ppm SO(2), the inhibition of C(3)H(8)-SCR below 673 K is more significant than that at high temperature above 673 K. Ag-Mn/H-BEA is a promising catalyst for the removal of NO(x) from diesel engine exhaust.

  20. Fabrication of Z-scheme Ag3PO4/MoS2 composites with enhanced photocatalytic activity and stability for organic pollutant degradation

    NASA Astrophysics Data System (ADS)

    Zhu, Chaosheng; Zhang, Lu; Jiang, Bo; Zheng, Jingtang; Hu, Ping; Li, Sujuan; Wu, Mingbo; Wu, Wenting

    2016-07-01

    In this study, highly efficient visible-light-driven Ag3PO4/MoS2 composite photocatalysts with different weight ratios of MoS2 were prepared via the ethanol-water mixed solvents precipitation method and characterized by ICP, XRD, HRTEM, FE-SEM, BET, XPS, UV-vis DRS and PL analysis. Under visible-light irradiation, Ag3PO4/MoS2 composites exhibit excellent photocatalytic activity towards the degradation of organic pollutants in aqueous solution. The optimal composite with 0.648 wt% MoS2 content exhibits the highest photocatalytic activity, which can degrade almost all MB under visible-light irradiation within 60 min. Recycling experiments confirmed that the Ag3PO4/MoS2 catalysts had superior cycle performance and stability. The photocatalytic activity enhancement of Ag3PO4/MoS2 photocatalysts can be mainly ascribed to the efficient separation of photogenerated charge carriers and the stronger oxidation and reduction ability through a Z-scheme system composed of Ag3PO4, Ag and MoS2, in which Ag particles act as the charge separation center. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Ag3PO4 by transferring the photogenerated electrons of Ag3PO4 to MoS2. The evidence of the Z-scheme photocatalytic mechanism of the composite photocatalysts could be obtained from the active species trapping experiments and the photoluminescence technique.