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Sample records for ags accelerator complex

  1. Injection and acceleration of Au31+ in the BNL AGS.

    SciTech Connect

    Fischer,W.; Ahrens, L.; Brown, K.; Gardner, C.; Glenn, W.; Huang, H.; Mapes, M.; Smart, L.; Thieberger, P.; Tsoupas, N.; Zhang, S.Y.; Zeno, K.; Omet, C.; Spiller, P.

    2008-06-23

    Injection and acceleration of ions in a lower charge state reduces space charge effects, and, if further elcctron stripping is needed, may allow elimination of a stripping stage and the associated beam losses. The former is of interest to the accelerators in the GSI FAIR complex, the latter for BNL RHIC collider operation at energies lower than the current injection energy. Lower charge state ions, however, have a higher likelihood of electron stripping which can lead to dynamic pressures rises and subsequent beam losses. We report on experiments in the AGS where Au{sup 31+} ions were injected and accelerated instead of the normally used Au{sup 77+} ions. Beam intensities and the average pressure in the AGS ring are recorded, and compared with calculations for dynamic pressures and beam losses. The experimental results will be used to benchmark the StrahlSim dynamic vacuum code and will be incorporated in the GSI FAIR SIS100 design.

  2. POLARIZED PROTON ACCELERATION AT THE BROOKHAVEN AGS - AN UPDATE.

    SciTech Connect

    HUANG,H.; AHRENS,L.; ALESSI,J.; BAI,M.; BEEBE-WANG,J.; BROWN,K.A.; GLENN,W.; LUCCIO,A.U.; MACKAY,W.W.; MONTAG,C.; PTITSYN,V.; ROSER,T.; TSOUPAS,N.; ZELENSKI,A.; ZENO,K.; CADMAN,B.; SPINKA,H.; UNDERWOOD,D.; RANJBAR,V.

    2002-06-02

    The RHIC spin design goal assumes 2 x 10{sup 11} proton/bunch with 70% polarization. As the injector to RHIC, polarized protons have been accelerated at the AGS for years to increase the polarization transmission efficiency. Several novel techniques have been applied in the AGS to overcome the intrinsic and imperfection resonances. The present level of accelerator performance is discussed. Progress on understanding the beam polarization behavior is presented. The outlook and future plan are also discussed.

  3. Polarized proton acceleration program at the AGS and RHIC

    SciTech Connect

    Lee, Y.Y.

    1995-06-01

    Presented is an overview of the program for acceleration of polarized protons in the AGS and their injection into the RHIC collider. The problem of depolarizing resonances in strong focusing circulator accelerators is discussed. The intrinsic resonances are jumped over by the fast tune jump, and a partial Siberian Snake is used to compensate for over forty imperfection resonances in the AGS. Two sets of full Siberian Snake and spin rotators will be employed in RHIC.

  4. 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.

  5. Polarized Proton Acceleration in AGS and RHIC

    SciTech Connect

    Roser, Thomas

    2008-02-06

    As the first hadron accelerator and collider consisting of two independent superconducting rings RHIC has operated with a wide range of beam energies and particle species including polarized proton beams. The acceleration of polarized beams in both the injector and the collider rings is complicated by numerous depolarizing spin resonances. Partial and full Siberian snakes have made it possible to overcome the depolarization and beam polarizations of up to 65% have been reached at 100 GeV in RHIC.

  6. POLARIZED PROTON ACCELERATION IN AGS AND RHIC.

    SciTech Connect

    ROSER,T.

    2007-09-10

    As the first hadron accelerator and collider consisting of two independent superconducting rings RHIC has operated with a wide range of beam energies and particle species including polarized proton beams. The acceleration of polarized beams in both the injector and the collider rings is complicated by numerous depolarizing spin resonances. Partial and full Siberian snakes have made it possible to overcome the depolarization and beam polarizations of up to 65% have been reached at 100 GeV in RHIC.

  7. Improvement Plans of Fermilab's Proton Accelerator Complex

    SciTech Connect

    Shiltsev, Vladimir

    2016-01-01

    The flagship of Fermilab's long term research program is the Deep Underground Neutrino Experiment (DUNE), located Sanford Underground Research Facility (SURF) in Lead, South Dakota, which will study neutrino oscillations with a baseline of 1300 km. The neutrinos will be produced in the Long Baseline Neutrino Facility (LBNF), a proposed new beam line from Fermilab's Main Injector. The physics goals of the DUNE require a proton beam with a power of some 2.4 MW at 120 GeV, which is roughly four times the current maximum power. Here I discuss current performance of the Fermilab proton accelerator complex, our plans for construction of the SRF proton linac as key part of the Proton Improvement Plan-II (PIP-II), outline the main challenges toward multi-MW beam power operation of the Fermilab accelerator complex and the staged plan to achieve the required performance over the next 15 years.

  8. Luminescence sensitization of Tb(3+)-DNA complexes by Ag().

    PubMed

    Xu, Lijun; Zhou, Lu; Chen, Xing; Shen, Xiaoqiang; Wang, Jine; Zhang, Jianye; Pei, Renjun

    2017-03-03

    Terbium ions (Tb(3+)) with unique photophysical properties have been utilized to develop biosensors with low background and high sensitivity. In this study, the Ag(+)-sensitized luminescence of Tb(3+)-DNA complexes was uncovered. The luminescence of Tb(3+)-DNA complexes could be enhanced by more than 30 times in the presence of Ag(+), when Tb(3+) was bound with poly(G) and poly(T) whereas not with other homopolymers. This research confirmed that the sensitization resulted from the interaction of Ag(+) with certain bases involved in DNA, not just with the reported certain G-quadruplex sequence. The coordination of Ag(+) to guanine and thymine bases was expected to increase their rigidities, form Tb(3+)-DNA-Ag(+) ternary structures, and thus enhance energy transfer from guanine and thymine to Tb(3+). These findings benefit the development of sensitive luminescence probes for various nucleic acids-related targets.

  9. Polarized Proton Acceleration in the AGS with Two Helical Partial Snakes

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

    Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and are not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.

  10. Polarized Proton Acceleration in the AGS with Two Helical Partial Snakes

    SciTech Connect

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

    2007-06-13

    Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and are not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.

  11. ACCELERATION OF POLARIZED PROTONS IN THE AGS WITH TWO HELICAL PARTIAL SNAKES.

    SciTech Connect

    HUANG, H.; AHRENS, L.A.; BAI, M.; BRAVAR, A.; BROWN, K.; COURANT, E.D.; GARDNER, C.; GLENN, J.W.; LUCCIO, A.U.; MACKAY, W.W.; PTITSYN, V.; ROSER, T.; TEPIKIAN, S.; TSOUPAS, N.; WOOD, J.; YIP, K.; ZELENSKI, A.; ZENO, K.

    2006-06-26

    Acceleration of polarized protons in the energy range of 5 to 25 GeV is particularly difficult: the depolarizing resonances are strong enough to cause significant depolarization but full Siberian snakes cause intolerably large orbit excursions and are not feasible in the AGS since straight sections are too short. Recently, two helical partial snakes with double pitch design have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances encountered during acceleration. This paper presents the accelerator setup and preliminary results.

  12. Synthesis, characterization and antimycobacterial activity of Ag(I)-aspartame, Ag(I)-saccharin and Ag(I)-cyclamate complexes.

    PubMed

    Cavicchioli, Maurício; Leite, Clarice Q F; Sato, Daisy N; Massabni, Antonio C

    2007-10-01

    The present work describes the synthesis and antimycobacterial activity of three Ag(I)-complexes with the sweeteners aspartame, saccharin, and cyclamate as ligands, with the aim of finding new candidate substances for fighting tuberculosis and other mycobacterial infections. The minimal inhibitory concentration of these three complexes was investigated in order to determine their in-vitro antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium malmoense, and Mycobacterium kansasii. The MIC values were determined using the Microplate Alamar Blue Assay. The best MIC values found for the complexes were 9.75 microM for Ag(I)-aspartame against M. kansasii and 15.7 microM for Ag(I)-cyclamate against M. tuberculosis.

  13. 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.

  14. Complexation and phase evolution at dimethylformamide-Ag(111) interfaces

    DOE PAGES

    Song, Wentao; Leung, Kevin; Shao, Qian; ...

    2016-09-15

    The interaction of solvent molecules with metallic surfaces impacts many interfacial chemical processes. We investigate the chemical and structure evolution that follows adsorption of the polar solvent dimethylformamide (DMF) on Ag(111). An Ag(DMF)2 coordination complex forms spontaneously by DMF etching of Ag(111), yielding mixed films of the complexes and DMF. Utilizing ultrahigh vacuum scanning tunneling microscopy (UHV-STM), in combination with X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) computations, we map monolayer phases from the 2-D gas regime, consisting of a binary mixture of DMF and Ag(DMF)2, through the saturation monolayer limit, in which these two chemical species phasemore » separate into ordered islands. Structural models for the near-square DMF phase and the chain-like Ag(DMF)2 phase are presented and supported by DFT computation. Interface evolution is summarized in a surface pressure-composition phase diagram, which allows structure prediction over arbitrary experimental conditions. In conclusion, this work reveals new surface coordination chemistry for an important electrolyte-electrode system, and illustrates how surface pressure can be used to tune monolayer phases.« less

  15. Complexation and phase evolution at dimethylformamide-Ag(111) interfaces

    SciTech Connect

    Song, Wentao; Leung, Kevin; Shao, Qian; Gaskell, Karen J.; Reutt-Robey, Janice E.

    2016-09-15

    The interaction of solvent molecules with metallic surfaces impacts many interfacial chemical processes. We investigate the chemical and structure evolution that follows adsorption of the polar solvent dimethylformamide (DMF) on Ag(111). An Ag(DMF)2 coordination complex forms spontaneously by DMF etching of Ag(111), yielding mixed films of the complexes and DMF. Utilizing ultrahigh vacuum scanning tunneling microscopy (UHV-STM), in combination with X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) computations, we map monolayer phases from the 2-D gas regime, consisting of a binary mixture of DMF and Ag(DMF)2, through the saturation monolayer limit, in which these two chemical species phase separate into ordered islands. Structural models for the near-square DMF phase and the chain-like Ag(DMF)2 phase are presented and supported by DFT computation. Interface evolution is summarized in a surface pressure-composition phase diagram, which allows structure prediction over arbitrary experimental conditions. In conclusion, this work reveals new surface coordination chemistry for an important electrolyte-electrode system, and illustrates how surface pressure can be used to tune monolayer phases.

  16. Vacuum systems of linear accelerators of the NICA injection complex

    NASA Astrophysics Data System (ADS)

    Kosachev, V. V.; Bazanov, A. M.; Butenko, A. V.; Galimov, A. R.; Nesterov, A. V.; Pivin, R. V.; Smirnov, A. V.

    2016-12-01

    The NICA project, which includes several accelerators of charged particles, is under construction in the Laboratory of High Energy Physics, Joint Institute for Nuclear Research (JINR), Dubna. Obtaining the required vacuum conditions is one of the key points in implementing the project, because reaching the required ion lifetime at all stages of particle acceleration is what determines the effective luminosity of the experiments in the long run. Currently, modernization of the vacuum system of the injection complex of the LU-20 linear accelerator of light ions, one of oldest accelerators in the JINR, is being carried out and the new HILAC linear accelerator for the acceleration of gold ions in the collider mode of the NICA complex is being installed. At the end parts of the linear accelerators, the residual gas pressure must be approximately 10-5 Pa, which is determined by the maximum amplitude of the RF electric field used for the acceleration of ions.

  17. Progress Towards Doubling the Beam Power at Fermilab's Accelerator Complex

    SciTech Connect

    Kourbanis, Ioanis

    2014-07-01

    After a 16 month shutdown to reconfigure the Fermilab Accelerators for high power operations, the Fermilab Accelerator Complex is again providing beams for numerous Physics Experiments. By using the Recycler to slip stack protons while the Main Injector is ramping, the beam power at 120 GeV can reach 700 KW, a factor of 2 increase. The progress towards doubling the Fermilab's Accelerator complex beam power will be presented.

  18. Soviet Accelerating and Storage Complex (UNK)

    NASA Astrophysics Data System (ADS)

    Kotchetkov, Dmitri

    2017-01-01

    During 1980s and 1990s a proton-proton collider named the Accelerating and Storage Complex (UNK) was under construction in the Soviet Union and then in Russia. The collider was supposed to be built in a 21 km long underground tunnel at the site of Institute for High Energy Physics in Protvino. With a design collision energy of 6 TeV and a luminosity of 4 x 1034 cm-1s-1, the UNK was planned to be become a primary energy frontier facility to further expand national high energy physics program, as well as to strengthen global scientific outreach and collaborations. The UNK was to be realized in 3 rings. The first ring, built from conventional magnets, was planned to be used for fixed target experiments with proton beam energies up to 600 GeV, and as an injector to the second and the third rings. The second and the third superconducting magnet rings were designed for either 3 TeV beam energy fixed target experiments or 6 TeV collider experiments. The top magnetic field of 1 T of the first ring was to be supplied by 2196 dipoles and 503 quadrupoles. Each of the second and the third superconducting rings would have needed 2192 dipoles and 474 quadrupoles to reach the top field of 5 T. ``Neptun'' experiment was supposed to be a centerpiece of the initial physics program at the UNK. 1560 conventional dipoles and 473 conventional quadrupoles were fabricated as a part of the first ring infrastructure. Several test versions of the superconducting magnets were produced, as well. While the tunnel and a proton injection line were completed by 1995, the reduction of Russian federal funding for high energy physics halted the project at the end of 1990s.

  19. ACCELERATION OF POLARIZED PROTONS IN THE AGS WITH TWO HELICAL PARTIAL SNAKES.

    SciTech Connect

    HUANG,H.; AHRENS,L.; BAI,M.; ET AL.

    2005-05-16

    The RHIC spin program requires 2 x 10{sup 11} proton/bunch with 70% polarization. As the injector to RHIC, AGS is the bottleneck for preserving polarization: there is no space for a full snake to overcome numerous depolarizing resonances. An ac dipole and a partial snake have been used to preserve beam polarization in the past few years. Two helical snakes have been built and installed in the AGS. With careful setup of optics at injection and along the ramp, this combination can eliminate all depolarizing resonances encountered during acceleration. This paper presents the setup and preliminary results.

  20. FFAG ACCELERATOR AS A NEW INJECTOR FOR THE BNL-AGS.

    SciTech Connect

    RUGGIERO, A.G.

    2004-10-13

    It has been proposed recently to upgrade the Alternating-Gradient Synchrotron (AGS) of Brookhaven National Laboratory (BNL) to an average proton beam power of one MWatt at the top energy of 28 GeV. This is to be accomplished primarily by raising the AGS repetition rate from the present {approx} 1/3 to 2.5 pulses per second, and by a relatively modest increase of beam intensity from the present 0.7 to about 1.0 x 10{sup 14} protons per cycle. The present injector, the 1.5 GeV Booster, has a circumference a quarter of that of the AGS, and four successive beam pulses are required for a complete fill of the AGS. The filling time at injection is thus at least 0.5 seconds, and it ought to be eliminated if one desires to shorten the AGS cycle period. Moreover, holding the beam for such a long period of time during injection causes its quality to deteriorate and beam losses. This report is the summary of the results of a feasibility study of a 1.5 GeV Fixed-Field Alternating-Gradient (FFAG) Accelerator as a new possible injection to the AGS.

  1. 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.

  2. Discrete and Polymeric, Mono- and Dinuclear Silver Complexes of a Macrocyclic Tetraoxime Ligand with AgI–AgI Interactions

    PubMed Central

    Tashiro, Shohei; Tanihira, Jun-ichiro; Yamada, Mihoko; Shionoya, Mitsuhiko

    2013-01-01

    Macrocyclic compounds that can bind cationic species efficiently and selectively with their cyclic cavities have great potential as excellent chemosensors for metal ions. Recently, we have developed a tetraoxime-type tetraazamacrocyclic ligand 1 formed through a facile one-pot cyclization reaction. Aiming to explore and bring out the potential of the tetraoxime macrocycle 1 as a chelating sensor, we report herein the preparation of several kinds of silver complexes of 1 and their unique coordination structures determined by single-crystal X-ray diffraction analyses. As a result, the formation of two kinds of discrete structures, monomeric complexes [Ag(1)X] (X = counter anions) and a dimeric complex [Ag2(1)2]X2, and two kinds of polymeric structures from a mononuclear complex, [Ag(1)]nXn, and from a dinuclear complex, [Ag2(1)X2]n, was demonstrated. In the resulting complexes, the structurally flexible macrocyclic ligand 1 was found to provide several different coordination modes. Notably, in some silver complexes of 1, AgI–AgI interactions were observed with different AgI–AgI distances which depend on the kind of counter anions and the chemical composition. PMID:23645105

  3. HBsAg sT123N mutation induces stronger antibody responses to HBsAg and HBcAg and accelerates in vivo HBsAg clearance.

    PubMed

    Li, Songxia; Zhao, Kaitao; Liu, Shuhui; Wu, Chunchen; Yao, Yongxuan; Cao, Liang; Hu, Xue; Zhou, Yuan; Wang, Yun; Pei, Rongjuan; Lu, Mengji; Chen, Xinwen

    2015-12-02

    Immune escape mutants with mutations in the hepatitis B surface antigen (HBsAg) major hydrophilic region (MHR) often emerge in association with diagnostic failure or breakthrough of HBV infection in patients with anti-HBs antibodies. Some mutants harboring substitutions to Asn in HBsAg MHR may have an additional potential N-glycosylation site. We have previously showed that sT123N substitution could generate additional N-glycosylated forms of HBsAg. In the present study, 1.3-fold-overlength HBV genomes containing the sT123N substitution were digested from the pHBV1.3-sT123N construct and subcloned into the pAAV vector to generate pAAV1.3-sT123N for hydrodynamic injection (HI) in mice. Viral expression and replication were phenotypically characterized by transient transfection. The results demonstrated that sT123N substitution impaired virion secretion, resulting in intracellular retention of HBcAg. Using the HBV HI mouse model, we found that mice mounted significantly stronger antibody responses to HBsAg and HBcAg, which accelerated HBsAg clearance. Thus, additional N-glycosylation generated by amino acid substitutions in HBsAg MHR may significantly modulate specific host immune responses and influence HBV infection in vivo. Our results help further the understanding of the role of immune escape mutants with N-linked glycosylation in the biology of HBV infection.

  4. Accelerator mass spectrometry analysis of ultra-low-level (129)I in carrier-free AgI-AgCl sputter targets.

    PubMed

    Liu, Qi; Hou, Xiaolin; Zhou, Weijian; Fu, Yunchong

    2015-05-01

    Separation of carrier-free iodine from low-level iodine samples and accurate measurement of ultra-low-level (129)I in microgram iodine target are essential but a bottleneck in geology and environment research using naturally produced (129)I. This article presents a detection technique of accelerator mass spectrometry (AMS) for accurate determination of ultra-low-level (129)I in carrier-free AgI-AgCl sputter targets. Copper instead of aluminum was selected as the suitable sample holder material to avoid the reaction of AgI-AgCl powder with aluminum. Niobium powder was selected as thermally and electrically conductive matrix to be mixed with AgI-AgCl powder, in order to obtain and maintain a stable and high iodine ion current intensity, as well as less memory effect and low background level of (129)I. The most optimal ratio of the Nb matrix to the AgI-AgCl powder was found to be 5:1 by mass. The typical current of (127)I(5+) using AgI-AgCl targets with iodine content from 5 to 80 μg was measured to be 5 to 100 nA. Four-year AMS measurements of the (129)I/(127)I ratios in standards of low iodine content and the machine blanks showed a good repeatability and stability.

  5. AGS SUPER NEUTRINO BEAM FACILITY ACCELERATOR AND TARGET SYSTEM DESIGN (NEUTRINO WORKING GROUP REPORT-II).

    SciTech Connect

    DIWAN,M.; MARCIANO,W.; WENG,W.; RAPARIA,D.

    2003-04-21

    This document describes the design of the accelerator and target systems for the AGS Super Neutrino Beam Facility. Under the direction of the Associate Laboratory Director Tom Kirk, BNL has established a Neutrino Working Group to explore the scientific case and facility requirements for a very long baseline neutrino experiment. Results of a study of the physics merit and detector performance was published in BNL-69395 in October 2002, where it was shown that a wide-band neutrino beam generated by a 1 MW proton beam from the AGS, coupled with a half megaton water Cerenkov detector located deep underground in the former Homestake mine in South Dakota would be able to measure the complete set of neutrino oscillation parameters: (1) precise determination of the oscillation parameters {Delta}m{sub 32}{sup 2} and sin{sup 2} 2{theta}{sub 32}; (2) detection of the oscillation of {nu}{sub {mu}}-{nu}{sub e} and measurement of sin{sup 2} 2{theta}{sub 13}; (3) measurement of {Delta}m{sub 21}{sup 2} sin 2{theta}{sub 12} in a {nu}{sub {mu}} {yields} {nu}{sub e} appearance mode, independent of the value of {theta}{sub 13}; (4) verification of matter enhancement and the sign of {Delta}m{sub 32}{sup 2}; and (5) determination of the CP-violation parameter {delta}{sub CP} in the neutrino sector. This report details the performance requirements and conceptual design of the accelerator and the target systems for the production of a neutrino beam by a 1.0 MW proton beam from the AGS. The major components of this facility include a new 1.2 GeV superconducting linac, ramping the AGS at 2.5 Hz, and the new target station for 1.0 MW beam. It also calls for moderate increase, about 30%, of the AGS intensity per pulse. Special care is taken to account for all sources of proton beam loss plus shielding and collimation of stray beam halo particles to ensure equipment reliability and personal safety. A preliminary cost estimate and schedule for the accelerator upgrade and target system are also

  6. Software Accelerates Computing Time for Complex Math

    NASA Technical Reports Server (NTRS)

    2014-01-01

    Ames Research Center awarded Newark, Delaware-based EM Photonics Inc. SBIR funding to utilize graphic processing unit (GPU) technology- traditionally used for computer video games-to develop high-computing software called CULA. The software gives users the ability to run complex algorithms on personal computers with greater speed. As a result of the NASA collaboration, the number of employees at the company has increased 10 percent.

  7. Exploration of complex multilayer film growth morphologies: STM analysis and predictive atomistic modeling for Ag on Ag(111)

    SciTech Connect

    Li, Maozhi; Chung, P.W.; Cox, E.; Jenks, C.J.; Thiel, P.A.; Evans, J.W.

    2008-01-03

    Scanning tunneling microscopy studies are integrated with development of a realistic atomistic model to both characterize and elucidate the complex mounded morphologies formed by deposition of Ag on Ag(111) at 150 and 180 K. Threefold symmetric lateral shapes of islands and mounds are shown to reflect the influence of a nonuniform step edge barrier inhibiting interlayer transport. Modeling of structure at the mound peaks leads to a sensitive estimate of the magnitude of this large barrier.

  8. Fermilab's Proton Accelerator Complex : World Record Performance and Upgrade Plans

    NASA Astrophysics Data System (ADS)

    Shiltsev, Vladimir

    2017-01-01

    The flagship of Fermilab's long term research program is the Deep Underground Neutrino Experiment (DUNE), located Sanford Underground Research Facility (SURF) in Lead, South Dakota, which will study neutrino oscillations with a baseline of 1300 km. The neutrinos will be produced in the Long Baseline Neutrino Facility (LBNF), a proposed new beam line from Fermilab's Main Injector. The physics goals of the DUNE require a proton beam with a power of some 2.4 MW at 120 GeV, which is roughly four times the current maximum power. Here I discuss current performance of the Fermilab proton accelerator complex, our plans for construction of the SRF proton linac as key part of the Proton Improvement Plan-II (PIP-II), outline the main challenges toward multi-MW beam power operation of the Fermilab accelerator complex and the staged plan to achieve the required performance over the next 15 years.

  9. Chemical mechanism of surface-enhanced Raman scattering via charge transfer in fluorenone-Ag complex

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Li, Yafei; Wu, Shiwei; Song, Peng; Xia, Lixin

    2016-06-01

    The intermolecular interaction between fluorenone (FN) and silver surfaces was investigated experimentally and theoretically. The structural, electronic and optical properties of the FN-Ag complex indicate that the carbonyl group O atom in FN molecules is the adsorbed position site to attach the silver substrate through the weak bond O…Ag. The analysis of vibrational modes and Raman activity of the largely enhanced Raman peaks using two FN-Ag4-x (x  =  l, s) complex models reveals that only the a1 vibrational modes with C 2v symmetry are selectively enhanced, from the point view of the change of dipole moment and polarizability induced by the interaction between FN and Ag4 substrate. Furthermore, the direct visualized evidence of the surface-enhanced Raman scattering (SERS) chemical enhancement mechanism for the FN-Ag complex is presented. The results reveal that only the intermolecular charge transfer with π-π transition characterization between FN and an Ag4 cluster facilitates the resonance Raman process and is directly responsible for chemical enhancement of Raman scattering of the FN-Ag complex.

  10. Fermilab’s Accelerator Complex: Current Status, Upgrades and Outlook

    SciTech Connect

    Convery, M. E.

    2016-10-31

    We report on the status of the Fermilab accelerator complex, including recent performance, upgrades in progress, and plans for the future. Beam delivery to the neutrino experiments surpassed our goals for the past year. The Proton Improvement Plan is well underway with successful 15 Hz beam operation. Beam power of 700 kW to the NOvA experiment was demonstrated and will be routine in the next year. We are also preparing the Muon Campus to commission beam to the g-2 experiment.

  11. Accelerated CO2 transport on surface of AgO nanoparticles in ionic liquid BMIMBF4

    NASA Astrophysics Data System (ADS)

    Ji, Dahye; Kang, Yong Soo; Kang, Sang Wook

    2015-11-01

    The AgO nanoparticles were utilized for a CO2 separation membrane. The AgO nanoparticles were successfully generated in ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIMBF4) by favorable interaction between the surface of particles and the counteranion of BMIMBF4. The generated AgO nanoparticles were confirmed by TEM, and the average size was 20 nm. Coordinative interactions of dissociated AgO particles with BMIM+BF4- were investigated by FT-Raman spectroscopy. When the ionic liquid BMIMBF4 containing AgO nanoparticles was utilized as a CO2 separation membrane, the separation performance was largely enhanced.

  12. Accelerated CO2 transport on surface of AgO nanoparticles in ionic liquid BMIMBF4

    PubMed Central

    Ji, Dahye; Kang, Yong Soo; Kang, Sang Wook

    2015-01-01

    The AgO nanoparticles were utilized for a CO2 separation membrane. The AgO nanoparticles were successfully generated in ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate (BMIMBF4) by favorable interaction between the surface of particles and the counteranion of BMIMBF4. The generated AgO nanoparticles were confirmed by TEM, and the average size was 20 nm. Coordinative interactions of dissociated AgO particles with BMIM+BF4− were investigated by FT-Raman spectroscopy. When the ionic liquid BMIMBF4 containing AgO nanoparticles was utilized as a CO2 separation membrane, the separation performance was largely enhanced. PMID:26549605

  13. Investigating the adiabatic beam grouping at the NICA accelerator complex

    NASA Astrophysics Data System (ADS)

    Brovko, O. I.; Butenko, A. V.; Grebentsov, A. Yu.; Eliseev, A. V.; Meshkov, I. N.; Svetov, A. L.; Sidorin, A. O.; Slepnev, V. M.

    2016-12-01

    The NICA complex comprises the Booster and Nuclotron synchrotrons for accelerating particle beams to the required energy and the Collider machine, in which particle collisions are investigated. The experimental heavy-ion program deals with ions up to Au+79. The light-ion program deals with polarized deuterons and protons. Grouping of a beam coasting in an ion chamber is required in many parts of the complex. Beam grouping may effectively increase the longitudinal emittance and particle losses. To avoid these negative effects, various regimes of adiabatic grouping have been simulated and dedicated experiments with a deuteron beam have been conducted at the Nuclotron machine. As a result, we are able to construct and optimize the beam-grouping equipment, which provides a capture efficiency near 100% either retaining or varying the harmonic multiplicity of the HF system.

  14. Ru-Ag and Ru-Au dicarbene complexes from an abnormal carbene ruthenium system.

    PubMed

    Bitzer, Mario J; Pöthig, Alexander; Jandl, Christian; Kühn, Fritz E; Baratta, Walter

    2015-07-14

    Reaction of [Ru(OAc)2(PPh3)2] with a P-functionalized imidazolium bromide easily affords a cationic abnormal carbene Ru system. Metalation with Ag2O yields a Ru-Ag complex containing an anionic dicarbene ligand, while subsequent transmetalation with Au(tht)Cl leads to the corresponding Ru-Au system. The bimetallic complexes were characterized by single crystal X-ray diffraction and are the first examples of complexes bearing anionic dicarbene ligands connecting two different d-block elements.

  15. Thermodynamic Equilibrium and Rise of Complexity in an Accelerated Universe

    NASA Astrophysics Data System (ADS)

    Moradpour, H.; Riazi, N.

    2016-01-01

    Observational data (Supernovae type Ia data) indicate that the rate of the universe expansion is increasing, which means that, in the framework of General Relativity, the current phase of the expansion is due to an unknown source of energy. Therefore, the nature of dominated fluid in cosmos, as the source of energy, is mysterious. Here, by considering this property of current accelerating phase along with the concept of thermodynamics equilibrium we try to find possible values for the state parameter ( ω) of the dominated fluid in a ( n+1)-dimensional Friedmann-Robertson-Walker universe. Our results are compatible with previous work for Gauss-Bonnet gravity and point to a universe which is so close to its thermodynamic equilibrium state. By the evolution of the cosmos, the baryonic content of the cosmos is participating in longer range interactions, including gravity and electromagnetism, and structure formation is begun which leads to an increase in the complexity content of the universe. Therefore, a true model for the cosmos should show this rise of complexity and information. In order to achieve this goal, we introduce a simple model including free particles in an expanding box and try to count the number of the states of energy. This configuration shows that the entropy of these number of states as the measure for complexity is increased when dominated fluid satisfies special condition ( ω ≥ -1) which is compatible with the results of the Supernovae type Ia data and the thermodynamic equilibrium conditions. Finally, We see that the rate of increase in the complexity content of the universe increases in the ω → -1 limit.

  16. Natural ageing process accelerates the release of Ag from functional textile in various exposure scenarios

    NASA Astrophysics Data System (ADS)

    Ding, Dahu; Chen, Lulu; Dong, Shaowei; Cai, Hao; Chen, Jifei; Jiang, Canlan; Cai, Tianming

    2016-11-01

    Natural ageing process occurs throughout the life cycle of textile products, which may possess influences on the release behavior of additives such as silver nanoparticles (Ag NPs). In this study, we assessed the releasability of Ag NPs from a Ag NPs functionalized textile in five different exposure scenarios (i.e. tap water (TW), pond water (PW), rain water (RW), artificial sweat (AS), and detergent solution (DS) along with deionized water (DW) as reference), which were very likely to occur throughout the life cycle of the textile. For the pristine textile, although the most remarkable release was found in DW (6–15 μg Ag/g textile), the highest release rate was found in RW (around 7 μg Ag/(g textile·h)). After ageing treatment, the total released Ag could be increased by 75.7~386.0% in DW, AS and DS. Morphological analysis clearly showed that the Ag NPs were isolated from the surface of the textile fibre due to the ageing treatment. This study provides useful information for risk assessment of nano-enhanced textile products.

  17. Natural ageing process accelerates the release of Ag from functional textile in various exposure scenarios

    PubMed Central

    Ding, Dahu; Chen, Lulu; Dong, Shaowei; Cai, Hao; Chen, Jifei; Jiang, Canlan; Cai, Tianming

    2016-01-01

    Natural ageing process occurs throughout the life cycle of textile products, which may possess influences on the release behavior of additives such as silver nanoparticles (Ag NPs). In this study, we assessed the releasability of Ag NPs from a Ag NPs functionalized textile in five different exposure scenarios (i.e. tap water (TW), pond water (PW), rain water (RW), artificial sweat (AS), and detergent solution (DS) along with deionized water (DW) as reference), which were very likely to occur throughout the life cycle of the textile. For the pristine textile, although the most remarkable release was found in DW (6–15 μg Ag/g textile), the highest release rate was found in RW (around 7 μg Ag/(g textile·h)). After ageing treatment, the total released Ag could be increased by 75.7~386.0% in DW, AS and DS. Morphological analysis clearly showed that the Ag NPs were isolated from the surface of the textile fibre due to the ageing treatment. This study provides useful information for risk assessment of nano-enhanced textile products. PMID:27869136

  18. Natural ageing process accelerates the release of Ag from functional textile in various exposure scenarios.

    PubMed

    Ding, Dahu; Chen, Lulu; Dong, Shaowei; Cai, Hao; Chen, Jifei; Jiang, Canlan; Cai, Tianming

    2016-11-21

    Natural ageing process occurs throughout the life cycle of textile products, which may possess influences on the release behavior of additives such as silver nanoparticles (Ag NPs). In this study, we assessed the releasability of Ag NPs from a Ag NPs functionalized textile in five different exposure scenarios (i.e. tap water (TW), pond water (PW), rain water (RW), artificial sweat (AS), and detergent solution (DS) along with deionized water (DW) as reference), which were very likely to occur throughout the life cycle of the textile. For the pristine textile, although the most remarkable release was found in DW (6-15 μg Ag/g textile), the highest release rate was found in RW (around 7 μg Ag/(g textile·h)). After ageing treatment, the total released Ag could be increased by 75.7~386.0% in DW, AS and DS. Morphological analysis clearly showed that the Ag NPs were isolated from the surface of the textile fibre due to the ageing treatment. This study provides useful information for risk assessment of nano-enhanced textile products.

  19. Accelerated Biofluid Filling in Complex Microfluidic Networks by Vacuum-Pressure Accelerated Movement (V-PAM).

    PubMed

    Yu, Zeta Tak For; Cheung, Mei Ki; Liu, Shirley Xiaosu; Fu, Jianping

    2016-09-01

    Rapid fluid transport and exchange are critical operations involved in many microfluidic applications. However, conventional mechanisms used for driving fluid transport in microfluidics, such as micropumping and high pressure, can be inaccurate and difficult for implementation for integrated microfluidics containing control components and closed compartments. Here, a technology has been developed termed Vacuum-Pressure Accelerated Movement (V-PAM) capable of significantly enhancing biofluid transport in complex microfluidic environments containing dead-end channels and closed chambers. Operation of the V-PAM entails a pressurized fluid loading into microfluidic channels where gas confined inside can rapidly be dissipated through permeation through a thin, gas-permeable membrane sandwiched between microfluidic channels and a network of vacuum channels. Effects of different structural and operational parameters of the V-PAM for promoting fluid filling in microfluidic environments have been studied systematically. This work further demonstrates the applicability of V-PAM for rapid filling of temperature-sensitive hydrogels and unprocessed whole blood into complex irregular microfluidic networks such as microfluidic leaf venation patterns and blood circulatory systems. Together, the V-PAM technology provides a promising generic microfluidic tool for advanced fluid control and transport in integrated microfluidics for different microfluidic diagnosis, organs-on-chips, and biomimetic studies.

  20. Synthesis and characterization of thiolate-Ag(I) complexes by solid-state and solution NMR and their antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Isab, Anvarhusein A.; Wazeer, Mohammed I. M.

    2007-02-01

    Silver(I) complexes of several thiolates have been prepared. These complexes have been characterized by elemental analysis and 13C NMR spectroscopy. All the Ag(I)-thiolate complexes are polymeric in nature. Therefore, 13C CP MAS NMR is being used extensively to analyze the binding site of the ligand and the nature of complexation. A significant shift difference was observed for S binding site whereas smaller shift was observed for carboxylate binding site. The antimicrobial activities for Ag(I)-glutathione complex was measured and compared with Ag(I)-captopril complex.

  1. Determining the Concentration Dependent Transformations of Ag Nanoparticles in Complex Media: Using SP-ICP-MS and Au@Ag Core-Shell Nanoparticles as Tracers.

    PubMed

    Merrifield, Ruth C; Stephan, Chady; Lead, Jamie

    2017-03-01

    The fate, behavior, and impact of engineered nanoparticles (NPs) in toxicological and environmental media are driven by complex processes which are difficult to quantify. A key limitation is the ability to perform measurements at low and environmentally relevant concentrations, since concentration may be a key factor determining fate and effects. Here, we use single particle inductively coupled mass spectroscopy (SP-ICP-MS) to measure directly NP diameter and particle number concentration of suspensions containing gold-silver core-shell (Au@Ag) NPs in EPA moderately hard water (MHW) and MHW containing 2.5 mg L(-1) Suwannee River fulvic acid. The Au core of the Au@Ag NPs acts as an internal standard, and aids in the analysis of the complex Ag transformations. The high sensitivity of SP-ICP-MS, along with the Au@Ag NPs, enabled us to track the NP transformations in the range 0.01 and 50 μg L(-1), without further sample preparation. On the basis of the analysis of both Au and Ag parameters (size, size distribution, and particle number), concentration was shown to be a key factor in NP behavior. At higher concentration, NPs were in an aggregation-dominated regime, while at the lower and environmentally representative concentrations, dissolution of Ag was dominant and aggregation was negligible. In addition, further formation of ionic silver as Ag NPs in the form of AgS or AgCl was shown to occur. Between 1 and 10 μg L(-1), both aggregation and dissolution were important. The results suggest that, under realistic conditions, the role of NP homoaggregation may be minimal. In addition, the complexity of exposure and dose in dose-response relationships is highlighted.

  2. 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.

  3. Ultrasound-accelerated organogel: application for visual discrimination of Hg(2+) from Ag(+).

    PubMed

    Wang, Yanqiu; Wang, Zengyao; Xu, Zhice; Yu, Xudong; Zhao, Kun; Li, Yajuan; Pang, Xuelei

    2016-02-21

    A new kind of naphthalimide-based organogelator, TN, was designed and synthesized. The intramolecular guanylation of TN promoted by Hg(2+) or Ag(+) in both solution and gel state was studied through several approaches including FL, UV-visible, NMR, FT-IR and SEM experiments. TN could selectively sense Hg(2+) and Ag(+) ions with obvious fluorescence quenching and color changes from yellow to colorless among test ions in the solution state. Interestingly, the S-gel of TN could be used to selectively discriminate Hg(2+) from Ag(+)via phase and morphology changes. Hg(2+) ions triggered the gel-to-gel transition with morphology changes of the TN S-gel from nanofibrils to porous sheet structure, together with fluorescence quenching. In contrast, the gel collapsed in the presence of Ag(+) ions, which was comprised of short and disordered fiber structure. To the best of the authors' knowledge, this is the first example of gels selectively sensing Hg(2+) or Ag(+)via a reaction approach.

  4. Ag(I)-cysteamine complex based electrochemical stripping immunoassay: ultrasensitive human IgG detection.

    PubMed

    Noh, Hui-Bog; Rahman, Md Aminur; Yang, Jee Eun; Shim, Yoon-Bo

    2011-07-15

    An ultrasensitive electrochemical immunosensor for a protein using a Ag (I)-cysteamine complex (Ag-Cys) as a label was fabricated. The low detection of a protein was based on the electrochemical stripping of Ag from the adsorbed Ag-Cys complex on the gold nanoparticles (AuNPs) conjugated human immunoglobulin G (anti-IgG) antibody (AuNPs-anti-IgG). The electrochemical immunosensor was fabricated by immobilizing anti-IgG antibody on a poly-5,2':5',2''-terthiophene-3'-carboxylic acid (polyTTCA) film grown on the glassy carbon electrode through the covalent bond formation between amine groups of anti-IgG and carboxylic acid groups of polyTTCA. The target protein, IgG was sandwiched between the anti-IgG antibody that covalently attached onto the polyTTCA layer and AuNPs-anti-IgG. Using square wave voltammetry, well defined Ag stripping voltammograms were obtained for the each target concentration. Various experimental parameters were optimized and interference effects from other proteins were checked out. The immunosensor exhibited a wide dynamic range with the detection limit of 0.4 ± 0.05 fg/mL. To evaluate the analytical reliability, the proposed immunosensor was applied to human IgG spiked serum samples and acceptable results were obtained indicating that the method can be readily extended to other bioaffinity assays of clinical or environmental significance.

  5. Solid and solution NMR studies of the complexation of Ag + with the trans isomer of captopril: Biological activities of this high blood pressure drug along with its Ag + complex

    NASA Astrophysics Data System (ADS)

    Isab, Anvarhusein A.; Wazeer, Mohamed I. M.

    2006-09-01

    Complexation of Ag + with captopril, 1-[(2 S)-3-mercapto-2-methylpropionyl]- L-proline, has been studied by 1H and 13C-NMR spectroscopy. The equilibrium constants for the trans to cis isomers of captopril bound to Ag + were measured by 1H NMR spectroscopy. It is observed that the trans isomer of the drug binds more strongly to Ag + between pH 5 and 8, as shown by the broadening of the trans isomer's resonances in 13C NMR spectra on complexation. A monodentate complexation of the trans captopril with Ag + via the thiol site is proposed based on the solid-state NMR and IR data. A superior antimicrobial activity is exhibited by the Cap-Ag(I) complex compared to captopril ligand itself against Heterotrotropic Plate Counts (HPC), Pseudomonas aeruginosa and Fecal streptococcus bacteria.

  6. Progress Towards Doubling the Beam Power at Fermilab's Accelerator Complex

    SciTech Connect

    Kourbanis, ioanis

    2014-06-01

    After a 14 month shutdown accelerator modifications and upgrades are in place to allow us doubling of the Main Injector beam power. We will discuss the past MI high power operation and the current progress towards doubling the power.

  7. Fluorescence enhancement of europium complexes by core-shell Ag@SiO₂ nanoparticles.

    PubMed

    Zhang, Hai-Xia; Lin, Xue-Mei; Wang, Ai-Ling; Zhao, Yong-Liang; Chu, Hai-Bin

    2015-12-05

    Three kinds of core-shell Ag@SiO2 nanoparticles with shell thickness of around 10, 15, and 25 nm, respectively, have been prepared by modified Stöber method and used for fluorescence enhancement. Six kinds of europium complexes with halobenzoic acid have been synthesized. Elemental analysis and lanthanide coordination titration show that the complexes have the compositions of Eu(p-XBA)3·H2O and Eu(o-XBA)3·2H2O (X=F, Cl, Br). The fluorescence spectra investigation indicates that the introduction of Ag@SiO2 nanoparticles into the europium complexes' solution can significantly enhance the fluorescence intensities of the complexes. The sequence of enhancement factors for halobenzoic acid complexes with different halogen atoms is Fcomplexes increase. When the thickness of the SiO2 shell is 25 nm, the fluorescence intensity of the europium complexes can reach a maximum enhancement factor of 5.1. The fluorescence enhancement mechanism may be the metal-enhanced fluorescence resulting from surface plasmon resonance of nanoparticles. And the nanoparticles near the complexes can effectively prevent complexes from the interaction with the solvent molecules, leading to a decrease of nonradiative energy transfer and the suppression of luminescence quench.

  8. Mycobacterial antigen 85 complex (Ag85) as a target for ficolins and mannose-binding lectin.

    PubMed

    Świerzko, Anna S; Bartłomiejczyk, Marcin A; Brzostek, Anna; Łukasiewicz, Jolanta; Michalski, Mateusz; Dziadek, Jarosław; Cedzyński, Maciej

    2016-06-01

    The pattern recognition molecules (PRMs) able to activate complement via the lectin pathway are suspected to be involved in the interaction between pathogenic Mycobacteria and the host immune response. Recently, we have found strong interactions between 25 and 35kDa mycobacterial cell fractions and mannose-binding lectin (MBL) and ficolins. Here we demonstrate that two biologically important mycobacterial structures, mannosylated lipoarabinomannan (ManLAM) and the antigen 85 (Ag85) complex, induce activation of the lectin pathway of complement. The strong interaction of recombinant MBL with purified ManLAM was confirmed, but no binding of recombinant ficolins (ficolin-1, -2, -3) with this structure was observed. Interestingly, all PRMs tested reacted with the mycobacterial antigen 85 (Ag85) complex. Based on the use of specific inhibitors (mannan for MBL, acetylated bovine serum albumin for ficolin-1 and -2, Hafnia alvei PCM 1200 lipopolysaccharide for ficolin-3), we concluded that carbohydrate-recognition (MBL) and fibrinogen-like domains (ficolins) were involved in these interactions. Our results indicate that the mycobacterial antigen 85 complex is a target for ficolins and MBL. Furthermore, those PRMs also bound to fibronectin and therefore might influence the Ag85 complex-dependent interaction of Mycobacterium with the extracellular matrix.

  9. Ag[Fe(CO)5]2(+) : a bare silver complex with Fe(CO)5 as a ligand.

    PubMed

    Malinowski, Przemysław J; Krossing, Ingo

    2014-12-01

    Attempts to prepare Fe(CO)5 (+) from Ag[Al(OR(F) )4 ] (R(F) =C(CF3 )3 ) and Fe(CO)5 in CH2 Cl2 yielded the first complex of a neutral metal carbonyl bound to a simple metal cation. The Ag[Fe(CO)5 ]2 (+) cation consists of two Fe(CO)5 molecules coordinating Ag(+) in an almost linear fashion. The ν(CO) modes are blue-shifted compared to Fe(CO)5 , with one band above 2143 cm(-1) indicating that back-bonding is heavily decreased in the Ag[Fe(CO)5 ]2 (+) cation.

  10. Surface structure of the Ag-In-(rare earth) complex intermetallics

    NASA Astrophysics Data System (ADS)

    Hars, S. S.; Sharma, H. R.; Smerdon, J. A.; Yadav, T. P.; Al-Mahboob, A.; Ledieu, J.; Fournée, V.; Tamura, R.; McGrath, R.

    2016-05-01

    We present a study of the surface structure of the Ag-In-RE (RE: rare-earth elements Gd, Tb, and Yb) complex intermetallics using scanning tunneling microscopy and low-energy electron diffraction. The surface of the Ag-In-Yb approximant prepared by sputter-annealing methods under ultrahigh-vacuum conditions produces a flat (100) surface with no facets. However, the Ag-In-Gd and Ag-In-Tb 1/1 approximants, which have a surface miscut of about 12∘ relative to the (100) plane, develop surface facets along various crystallographic directions. The structure of each facet can be explained as a truncation of the rhombic triacontahedral clusters, i.e., the main building blocks of these systems. Despite their differences in atomic structure, symmetry, and density, the facets show common features. The facet planes are In rich. The analysis of the nearest-neighbor atom distances suggests that In atoms form bonds with the RE atoms, which we suggest is a key factor that stabilizes even low-density facet planes.

  11. Antigen-specific detection of HBsAG-containing immune complexes in the course of hepatitis B virus infection.

    PubMed Central

    Pernice, W; Sodomann, C P; Lüben, G; Seiler, F R; Sedlacek, H H

    1979-01-01

    In recent studies extrahepatic manifestations of viral hepatitis have been recognized as immune complex diseases. Hepatitis B surface antigen (HBsAg) has been successfully identified in immune complexes, but the pathogenic role of HBsAg-containing immune complexes (IC) remains questionable. The subject of the present study was the antigen-specific determination of IC in the course of hepatitis B virus infection using a new HBsAg-specific IC test (Pernice & Sedlacek, 1978). This test is based on the following principle: rabbit anti-HBs-coated polystyrole test tubes are incubated with the IC-containing test sample. The HBsAg-containing IC bind to the solid phase by their free antigenic determinants. There they can be quantified using a peroxidase-labelled anti-human IgG antibody. A good correlation was found between the level of HBsAg-containing immune complexes and the clinical state of six patients in a follow-up study. IC could be detected simultaneously with HBsAg and either decreased or disappeared before the occurrence of free anti-HBs. In the sera of an additional twenty-eight patient suffering from chronic active hepatitis, HBsAg-containing immune complexes were detected in 85% of cases. One patient suffering from polyarteritis nodosa was also positive. Occasionally, extremely high levels of IC were found in the course of these diseases. PMID:91465

  12. Excitation spectra of Ag3-DNA bases complexes: A benchmark study

    NASA Astrophysics Data System (ADS)

    Maksimov, D. A.; Pomogaev, V. A.; Kononov, A. I.

    2017-04-01

    Assessment of different ab initio and TDDFT methods was studied for calculation of the excitation energies of the complexes of pyrimidine bases with positively charged Ag3+ clusters. Performance of CIS, CIS(D), CC2, ADC(2), MP2, and TDDFT techniques with the use of different hybrid-GGA and meta-hybrid-GGA functionals and basis sets is studied. We found that M06-2X functional shows good accuracy in comparison with the ADC(2) ab initio method and that the geometry optimization approach can strongly affect the excitation spectra of the complexes. Our results may have important implications for further studies of ligand-stabilized silver nanoclusters.

  13. Unexpected Generation and Observation of a T-Shaped Complex of H_{2}C_{2}\\cdotsAgCCH

    NASA Astrophysics Data System (ADS)

    Walker, N. R.; Stephens, S. L.; Mizukami, W.; Tew, D. P.; Legon, A. C.

    2013-06-01

    An experiment to probe species generated within a supersonically-expanding jet consisting of SF_{6}, Ag, C_{2}H_{2} and argon by broadband rotational spectroscopy revealed the existence of a T-shaped complex of hitherto unknown origin. Empirical tests revealed that this complex requires the presence of C_{2}H_{2} and Ag within the gas sample. While the intensity of the associated transitions are enhanced by the presence of SF_{6}, theoretical calculations and empirical tests implied that the identified complex is H_{2}C_{2}\\cdotsAgCCH rather than the original target of the experiment, H_{2}C_{2}\\cdotsAgF. This deduction is now supported by evidence acquired through experiments exploiting ^{13}C-enriched isotopic samples. Transitions have been assigned for the H_{2}^{13}C_{2}\\cdotsAg^{13}C^{13}CH isotopologue. Data acquired from each isotopologue allows determination of the rotational constants (B}_{0}, C}_{0}) and centrifugal distortion constant, Δ_J}. The data are consistent with a T-shaped complex in which the Ag atom of AgCCH binds to electrons within the {π}-orbitals of ethyne. Preliminary determinations of bond lengths will be presented. Experiments are in progress to measure the spectra of deuterated isotopologues.

  14. Accelerating procelain formation by incorporating a complex additive

    SciTech Connect

    Maslennikova, G.N.; Dubovitskii, S.A.; Moroz, I.K.

    1986-05-01

    The authors studied the influence of a complex additive consisting of oxides of calcium, zinc, and magnesium on the formaton of porcelain. In order to achieve a more uniform distribution of the complex additive in the porcelain body it was incorporated in the form of water soluble salts-nitrates, which ensured comparability of results and excluded the effect of the different types of anions. The study of the main parameters of sintering (porosity, shrinkage, and mechanical strength) for the test bodies showed that they sinter at lower temperatures and attain zero porosity, maximum shrinkage, and mechanical strength. The most typical bodies indentified in this way were investigated by methods of complex differential thermal analysis and x-ray diffraction. Thus, the introduction of complex additives consisting of calcium, zinc, and magnesium oxides contributes to the earlier formation of porcelain. With the reduction of firing temperatures by 100/sup 0/C the authors observe an improvement in the basic properties of porcelain.

  15. Analysis of complex cardiovascular flow with three-component acceleration-encoded MRI.

    PubMed

    Barker, Alex J; Staehle, Felix; Bock, Jelena; Jung, Bernd A; Markl, Michael

    2012-01-01

    Functional information regarding cardiac performance, pressure gradients, and local flow derangement are available from blood acceleration fields. Thus, this study examines a 2D and 3D phase contrast sequence optimized to efficiently encode three-directional, time-resolved acceleration in vitro and in vivo. Stenosis phantom acceleration measurements were compared to acceleration derived from standard velocity encoded phase contrast-magnetic resonance imaging (i.e., "velocity-derived acceleration"). For in vivo analysis, three-directional 2D acceleration maps were compared to velocity-derived acceleration using regions proximal and distal to the aortic valve in six healthy volunteers at 1.5 and 3.0 T (voxel size = 1.4 × 2.1 × 8 mm, temporal resolution = 16-20 ms). In addition, a 4D acceleration sequence was evaluated for feasibility in a healthy volunteer and postrepair biscuspid aortic valve patient with an ascending aortic aneurysm. The phantom magnetic resonance acceleration measurements were more accurate (nonturbulent root mean square error = 2.2 vs. 5.1 m/s(2) for phase contrast-magnetic resonance imaging) and 10 times less noisy (nonturbulent σ = 0.9 vs. 13.6 m/s(2) for phase contrast-magnetic resonance imaging) than velocity-derived acceleration. Acceleration mapping of the left ventricular outflow tract and aortic arch exhibited signal voids colocated with complex flow events such as vortex formation and high order motion. 4D acceleration data, visualized in combination with the velocity data, may provide new insight into complex flow phenomena.

  16. H{sub 2}—AgCl: A spectroscopic study of a dihydrogen complex

    SciTech Connect

    Grubbs, G. S.; Obenchain, Daniel A.; Pickett, Herbert M.; Novick, Stewart E.

    2014-09-21

    H{sub 2}—AgCl has been observed on a Fourier transform microwave spectrometer equipped with laser ablation source and determined to be a dihydrogen complex. Transitions up to J = 3–2 have been measured and analyzed for four isotopologues of the complex containing ortho and para H{sub 2}. The ortho and para spin states have been included in one fit, a deviation from the typical H{sub 2} complex. Rotational constants B and C, centrifugal distortion constants Δ{sub J} and Δ{sub JK}, nuclear electric quadrupole coupling constants χ{sub aa}, χ{sub bb}, and χ{sub cc} for {sup 35}Cl and {sup 37}Cl have been fit for both spin states while nuclear spin-nuclear spin constants D{sub aa}, D{sub bb}, and D{sub cc}, and nuclear spin-rotation constant C{sub aa} have been reported for the ortho spin state. Quantum chemical calculations predict a strong bonding interaction and the strength of the complex has been related to reported χ{sub aa} and Δ{sub J} values amongst a host of comparable species, including the AgCl monomer itself. Bond lengths have been determined for Ag—Cl, Ag—H{sub 2} center-of-mass, and H—H and are reported.

  17. H2—AgCl: A spectroscopic study of a dihydrogen complex

    NASA Astrophysics Data System (ADS)

    Grubbs, G. S.; Obenchain, Daniel A.; Pickett, Herbert M.; Novick, Stewart E.

    2014-09-01

    H2—AgCl has been observed on a Fourier transform microwave spectrometer equipped with laser ablation source and determined to be a dihydrogen complex. Transitions up to J = 3-2 have been measured and analyzed for four isotopologues of the complex containing ortho and para H2. The ortho and para spin states have been included in one fit, a deviation from the typical H2 complex. Rotational constants B and C, centrifugal distortion constants ΔJ and ΔJK, nuclear electric quadrupole coupling constants χaa, χbb, and χcc for 35Cl and 37Cl have been fit for both spin states while nuclear spin-nuclear spin constants Daa, Dbb, and Dcc, and nuclear spin-rotation constant Caa have been reported for the ortho spin state. Quantum chemical calculations predict a strong bonding interaction and the strength of the complex has been related to reported χaa and ΔJ values amongst a host of comparable species, including the AgCl monomer itself. Bond lengths have been determined for Ag—Cl, Ag—H2 center-of-mass, and H—H and are reported.

  18. A novel chemiluminescence reaction system for the determination of norfloxacin with Ag(III) complex

    NASA Astrophysics Data System (ADS)

    Sun, Hanwen; Chen, Peiyun; Wang, Fei

    2009-10-01

    A novel chemiluminescence (CL) system for the determination of norfloxacin (NFLX) is developed based on the direct CL reaction of [Ag(HIO 6) 2] 5--H 2SO 4-NFLX system. The possible mechanism of CL emission and enhancing effect was discussed by comparing UV, fluorescence and CL spectra. [Ag(HIO 6) 2] 5- in the presence of H 2SO 4 could produce CL emission at 490 nm, this might be caused by the excited state (O 2) 2*. The enhancing effect of NFLX may be produced through an intermolecular energy transfer from part of (O 2) 2* to NFLX molecule and complex of Ag 3+ and NFLX. The CL intensity emission intensity was linear in the range 1.34 × 10 -8 to 5.44 × 10 -6 g mL -1 with correlation coefficient of 0.9982. The detection limit (s/n = 3) was 3.10 × 10 -9 g mL -1. The recovery was in the range of 90.0-104% with the RSD of 1.1-2.8%. The proposed flow injection CL method was applied satisfactorily for the determination of NFLX in capsule, human serum and urine.

  19. A novel chemiluminescence reaction system for the determination of norfloxacin with Ag(III) complex.

    PubMed

    Sun, Hanwen; Chen, Peiyun; Wang, Fei

    2009-10-15

    A novel chemiluminescence (CL) system for the determination of norfloxacin (NFLX) is developed based on the direct CL reaction of [Ag(HIO(6))(2)](5-)-H(2)SO(4)-NFLX system. The possible mechanism of CL emission and enhancing effect was discussed by comparing UV, fluorescence and CL spectra. [Ag(HIO(6))(2)](5-) in the presence of H(2)SO(4) could produce CL emission at 490 nm, this might be caused by the excited state (O(2))(2)*. The enhancing effect of NFLX may be produced through an intermolecular energy transfer from part of (O(2))(2)* to NFLX molecule and complex of Ag(3+) and NFLX. The CL intensity emission intensity was linear in the range 1.34 x 10(-8) to 5.44 x 10(-6) gmL(-1) with correlation coefficient of 0.9982. The detection limit (s/n=3) was 3.10 x 10(-9) gmL(-1). The recovery was in the range of 90.0-104% with the RSD of 1.1-2.8%. The proposed flow injection CL method was applied satisfactorily for the determination of NFLX in capsule, human serum and urine.

  20. Hardware acceleration vs. algorithmic acceleration: can GPU-based processing beat complexity optimization for CT?

    NASA Astrophysics Data System (ADS)

    Neophytou, Neophytos; Xu, Fang; Mueller, Klaus

    2007-03-01

    Three-dimensional computed tomography (CT) is a compute-intensive process, due to the large amounts of source and destination data, and this limits the speed at which a reconstruction can be obtained. There are two main approaches to cope with this problem: (i) lowering the overall computational complexity via algorithmic means, and/or (ii) running CT on specialized high-performance hardware. Since the latter requires considerable capital investment into rather inflexible hardware, the former option is all one has typically available in a traditional CPU-based computing environment. However, the emergence of programmable commodity graphics hardware (GPUs) has changed this situation in a decisive way. In this paper, we show that GPUs represent a commodity high-performance parallel architecture that resonates very well with the computational structure and operations inherent to CT. Using formal arguments as well as experiments we demonstrate that GPU-based 'brute-force' CT (i.e., CT at regular complexity) can be significantly faster than CPU-based as well as GPU-based CT with optimal complexity, at least for practical data sizes. Therefore, the answer to the title question: "Can GPU-based processing beat complexity optimization for CT?" is "Absolutely!"

  1. The operation of the LHC accelerator complex (1/2)

    SciTech Connect

    2010-04-07

    These lectures will give an overview of what happens when the LHC is in running mode. They are aimed at students working on the LHC experiments, but all those who are curious about what happens behind the scenes of the LHC are welcomed. You will learn all you always wanted to know about the LHC, and never had the courage to ask! The only pre-requisite is a basic, college-level, knowledge of EM and of the principles that allow to steer charged beams. Topics covered will include, among others: - the description of the injector chain, from the generation of the protons, to the delivery of bunches to the LHC. - the discussion of the steps required to accelerate the beams in the LHC, to bring them into collision, and to control the luminosity at the interaction points. - the description of the monitoring tools available to the LHC operators, and an explanation of the various plots and panels that can be found on the LHC web pages. o Lecture 1: Wednesday April 7, 10-11am o Lecture 2: Friday April 9, 10-11am The lectures will be webcast, recorded and archived. Coffee will be served before the lectures, starting at 9:45

  2. The operation of the LHC accelerator complex (2/2)

    SciTech Connect

    2010-04-09

    These lectures will give an overview of what happens when the LHC is in running mode. They are aimed at students working on the LHC experiments, but all those who are curious about what happens behind the scenes of the LHC are welcomed. You will learn all you always wanted to know about the LHC, and never had the courage to ask! The only pre-requisite is a basic, college-level, knowledge of EM and of the principles that allow to steer charged beams. Topics covered will include, among others: - the description of the injector chain, from the generation of the protons, to the delivery of bunches to the LHC. - the discussion of the steps required to accelerate the beams in the LHC, to bring them into collision, and to control the luminosity at the interaction points. - the description of the monitoring tools available to the LHC operators, and an explanation of the various plots and panels that can be found on the LHC web pages. o Lecture 1: Wednesday April 7, 10-11am o Lecture 2: Friday April 9, 10-11am The lectures will be webcast, recorded and archived. Coffee will be served before the lectures, starting at 9:45

  3. The operation of the LHC accelerator complex (2/2)

    ScienceCinema

    None

    2016-07-12

    These lectures will give an overview of what happens when the LHC is in running mode. They are aimed at students working on the LHC experiments, but all those who are curious about what happens behind the scenes of the LHC are welcomed. You will learn all you always wanted to know about the LHC, and never had the courage to ask! The only pre-requisite is a basic, college-level, knowledge of EM and of the principles that allow to steer charged beams. Topics covered will include, among others: - the description of the injector chain, from the generation of the protons, to the delivery of bunches to the LHC. - the discussion of the steps required to accelerate the beams in the LHC, to bring them into collision, and to control the luminosity at the interaction points. - the description of the monitoring tools available to the LHC operators, and an explanation of the various plots and panels that can be found on the LHC web pages. o Lecture 1: Wednesday April 7, 10-11am o Lecture 2: Friday April 9, 10-11am The lectures will be webcast, recorded and archived. Coffee will be served before the lectures, starting at 9:45

  4. The operation of the LHC accelerator complex (1/2)

    ScienceCinema

    None

    2016-07-12

    These lectures will give an overview of what happens when the LHC is in running mode. They are aimed at students working on the LHC experiments, but all those who are curious about what happens behind the scenes of the LHC are welcomed. You will learn all you always wanted to know about the LHC, and never had the courage to ask! The only pre-requisite is a basic, college-level, knowledge of EM and of the principles that allow to steer charged beams. Topics covered will include, among others: - the description of the injector chain, from the generation of the protons, to the delivery of bunches to the LHC. - the discussion of the steps required to accelerate the beams in the LHC, to bring them into collision, and to control the luminosity at the interaction points. - the description of the monitoring tools available to the LHC operators, and an explanation of the various plots and panels that can be found on the LHC web pages. o Lecture 1: Wednesday April 7, 10-11am o Lecture 2: Friday April 9, 10-11am The lectures will be webcast, recorded and archived. Coffee will be served before the lectures, starting at 9:45

  5. N-containing Ag(I) and Hg(II) complexes: a new class of antibiotics.

    PubMed

    Sabounchei, Seyyed Javad; Shahriary, Parisa

    2013-01-01

    Several classes of antimicrobial compounds are presently available; microorganism's resistance to these drugs constantly emerges. In order to prevent this serious medical problem, the elaboration of new types of antibacterial agents or the expansion of bioactivity of the naturally known biosensitive compounds is a very interesting research problem. The synthesis and characterization of metal complexes with organic bioactive ligands is one of the promising fields for the search. The biological activities of the metal complexes differ from those of either the ligand or the metal ion. The results obtained thus far have led to the conclusion that structural factors, which govern antimicrobial activities, are strongly dependent on the central metal ion. A review of papers dealing with the Ag(I) and Hg(II) complexes of N donor ligands is presented. These metal complexes of N-chelating ligands have attracted considerable attention because of their interesting physicochemical properties and pronounced biological activities. This review will mainly focus on the preparation procedures and antibacterial properties of free organic ligands and the corresponding complexes. Finally, a research about antimicrobial properties of new Hg(II) complexes with 5-methyl-5-(4-pyridyl)-2,4-imidazolidenedione (L) and various halogen ions, HgL2X2 (X = Cl¯ (49), Br¯ (50), and I¯ (51)), is reported. Noteworthy antimicrobial activities, evaluated by minimum inhibitory concentration, for these complexes were observed.

  6. Using Machine Learning to Accelerate Complex Atomic Structure Elucidation

    NASA Astrophysics Data System (ADS)

    Brouwer, William; Calderin, Lazaro; Sofo, Jorge

    2012-02-01

    Workers in various scientific disciplines seek to develop chemical models for extended and molecular systems. The modeling process revolves around the gradual refinement of model assumptions, through comparison of experimental and computational results. Solid state Nuclear Magnetic Resonance (NMR) is one such experimental technique, providing great insight into chemical order over Angstrom length scales. However, interpretation of spectra for complex materials is difficult, often requiring intensive simulations. Similarly, working forward from the model in order to produce experimental quantities via ab initio is computationally demanding. The work involved in these two significant steps, compounded by the need to iterate back and forth, drastically slows the discovery process for new materials. There is thus great motivation for the derivation of structural models directly from complex experimental data, the subject of this work. Using solid state NMR experimental datasets, in conjunction with ab initio calculations of measurable NMR parameters, a network of machine learning kernels are trained to rapidly yield structural details, on the basis of input NMR spectra. Results for an environmentally relevant material will be presented, and directions for future work.

  7. Arginine Silicate Inositol Complex Accelerates Cutaneous Wound Healing.

    PubMed

    Durmus, Ali Said; Tuzcu, Mehmet; Ozdemir, Oguzhan; Orhan, Cemal; Sahin, Nurhan; Ozercan, Ibrahim Hanifi; Komorowski, James Richard; Ali, Shakir; Sahin, Kazim

    2016-10-14

    Arginine silicate inositol (ASI) complex is a composition of arginine, silicon, and inositol that has been shown to have beneficial effects on vascular health. This study reports the effects of an ASI ointment on wound healing in rats. A full-thickness excision wound was created by using a disposable 5 mm diameter skin punch biopsy tool. In this placebo-controlled study, the treatment group's wound areas were covered by 4 or 10 % ASI ointments twice a day for 5, 10, or 15 days. The rats were sacrificed either 5, 10, or 15 days after the wounds were created, and biopsy samples were taken for biochemical and histopathological analysis. Granulation tissue appeared significantly faster in the ASI-treated groups than in the control groups (P < 0.05). The mean unhealed wound area was significantly smaller, and the mean percentage of total wound healing was significantly higher in ASI-treated wounds than in the control wounds. Hydroxyproline, collagen, and matrix metalloproteinases were measured in the granulated tissue and found to be affected. Inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), collagen, matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), epidermal growth factor (EGF), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and various cytokines (TNF-α and IL-1β) measured in this study showed a significant fall in expression level in ASI-treated wounds. The results suggest that topical application of ASI ointment (especially 4 % concentration) has beneficial effects on the healing response of an excisional wound.

  8. Adjunct immunotherapy with Ag85 complex proteins based subunit vaccine in a murine model of Mycobacterium tuberculosis infection.

    PubMed

    Giri, Pramod K; Verma, Indu; Khuller, Gopal K

    2009-01-01

    This study was designed to evaluate the immunotherapeutic potential of Mycobacterium tuberculosis Ag85AB emulsified with unmethylated CpG motif-containing oligonucleotide (CpG-ODN) and dimethyldioctadecylammonium bromide (DDA) adjuvants (Ag85AB-CpG-DDA) in conjunction with antituberculous drugs. Ag85 complex proteins of M. tuberculosis purified from total culture filtrate and purified proteins were emulsified with CpG-ODN and DDA adjuvants. Mice were infected with M. tuberculosis H37 Rv and left for 30 days to establish infection. These mice were named 'tuberculous mice'. Tuberculous mice were treated with Ag85AB-CpG-DDA alone or in conjunction with antituberculous drugs. Treatment of tuberculous mice with Ag85AB-CpG-DDA in conjunction with antituberculous drugs reduced significant bacilli burden in lung and spleen. Moreover, treatment of tuberculous mice with Ag85AB-CpG-DDA induced higher production of type-I cytokines, generated more CD44-positive T cells and suppresses secretion of IL-4 as compared with untreated animals. In conclusion, this study shows that Ag85AB-CpG-DDA formulation may act as a potential future therapeutic regimen in conjunction with antituberculous drugs.

  9. Evidence from Broadband Rotational Spectroscopy for a Complex Between AgCCH and C6H6

    NASA Astrophysics Data System (ADS)

    Zaleski, Daniel P.; Stephens, Susanna Louise; Walker, Nick; Legon, Anthony

    2014-06-01

    Last year, at the 68th International Symposium of Molecular Spectroscopy, the rotational spectrum of a complex formed between C2H2 and AgCCH was presented. The geometry was found to be T-shaped with the silver atom coordinated to the center of the CC bond in acetylene. Evidence for a new complex formed between AgCCH and C6H6 is now presented in the form of deep-averaged broadband rotational spectra. The spectra are observed only when both C2H2 and C6H6 are present in the gas sample. The relative intensities of the observed spectra are consistent with the naturally-occurring abundance ratio of the isotopes of silver. The shift on substitution of 107Ag for 109Ag implies a silver atom positioned close to the center of mass. The isotopic shifts observed when C2D2 is used as a precursor instead of C2H2 are also consistent with assignment to a complex formed between C6H6 and AgCCH/D. The geometry of the complex is yet to be precisely established.

  10. 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.

  11. Synthesis of a new electrically conducting nanosized Ag-polyaniline-silica complex using γ-radiolysis and its biosensing application

    NASA Astrophysics Data System (ADS)

    Kim, Hwa-Jung; Park, Sang Hyun; Park, Hae-Jun

    2010-08-01

    In this study, a new electrically conducting nanosized Ag-PANI-silica complex, in which nano-silver is bound to silica and polyaniline (PANI), has been synthesized by using γ-irradiation at room temperature and not by using polyvinylpyrrolidone (PVP) as a colloidal stabilizer. The conductivity of nanosized Ag-PANI-silica complex was determined by using the Van der PauW method, and the complex turned out to have a high semi-conductivity (200 S/cm). The optical property and morphology were characterized by using a UV-vis spectrophotometer, field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The optical absorption bands of UV-vis analysis revealed a peak at 262, 368, and a slowly decreasing band at 600-800 nm originating from the a nanosized Ag-PANI-silica complex. FE-SEM and TEM showed that the nanosized Ag-PANI-silica complex has a particle size ranging from 10 to 30 nm and high stability. The nano-complex prepared by γ-irradiation can be applicable to be used as biosensor materials.

  12. Ligand/cluster/support catalytic complexes in heterogeneous ultrananocatalysis: NO oxidation on Ag3/MgO(100).

    PubMed

    Sementa, Luca; Barcaro, Giovanni; Negreiros, Fabio R; Fortunelli, Alessandro

    2014-12-28

    In the present work we explore via first-principles simulations whether the ligand/cluster/support catalytic complex generated by CO oxidation over silver trimers deposited on the regular MgO(100) surface - i.e. a Ag3/carbonate or Ag3(CO3)/MgO(100) species - can be used as a catalyst in a different reaction: the selective oxidation of NO to NO2 (or NOox). The Ag3(CO3)/MgO(100) complex is first shown to be reasonably stable at room temperature in terms of both disaggregation and sintering, and that it can be generated from Ag3 adsorbed onto an oxygen vacancy defect of the regular MgO(100) surface under oxidation conditions. It is then found that the Ag3(CO3)/MgO(100) species transforms under NOox conditions into an even more complex aggregate, a mixed carbonate/double-nitrite Ag3(CO3)(NO2)2/MgO(100) species, which can then act as an efficient catalyst of NOox. It is noteworthy that under NOox reaction conditions a different ligand/cluster/support catalytic complex is formed with respect to the original COox one. These findings prove the diversity of the catalytic chemistry of subnanometer (or ultranano) metal clusters deposited on oxide substrates, associated with the formation of many different ligand/cluster/support aggregates, the vast amount of combinatorial possibilities thus opening, and the need for computational approaches to perform systematic structural and stoichiometric searches in order to cope with such a multiform diversity.

  13. Stacks and clips: Uncanny similarities in the modes of self-assembly in tenary Ag(I) complexes with 1,2-diazines and chelating heteroarenes

    PubMed Central

    Türkmen, Yunus E.; Sen, Saikat

    2014-01-01

    The first synthesis and structural elucidation of Ag(I) ternary complexes with 1,2-diazines and chelating heteroarenes have been described. Conserved modes of inter-cation Ag+⋯π and π⋯π stacking interactions result in near identical patterns of cation self-assembly in these ternary complexes. PMID:24701132

  14. Beam transport channels and beam injection and extraction systems of the NICA accelerator complex

    NASA Astrophysics Data System (ADS)

    Butenko, A. V.; Volkov, V. I.; Kolesnikov, S. Yu.; Meshkov, I. N.; Mikhaylov, V. A.; Rabtsun, S. V.; Sidorin, A. O.; Sidorov, A. I.; Topilin, N. D.; Trubnikov, G. V.; Tuzikov, A. V.; Fateev, A. A.; Shvetsov, V. S.

    2016-12-01

    A new accelerator complex is being constructed at the Joint Institute for Nuclear Research as a part of the Nuclotron-based Ion Collider fAcility (NICA) project. The goal is to conduct experiments with colliding ion beams (at the first stage of the project) and colliding polarized proton/deuteron beams (at the second stage). Transport beam channels and the systems of beam injection and extraction for synchrotrons and collider rings are an important connecting link for the whole accelerator facility. The design of the primary beam-transport channels and injection/extraction systems are presented. Special attention is paid to various aspects of dynamics of beams in their transfer between the NICA accelerators.

  15. Preparation of Novel Europium Complex Doped Ag@SiO2 Nanoparticles with Intense Fluorescence.

    PubMed

    Liu, Bing; Yin, Dongguang; Song, Kailin; Yang, Juan Ou; Wang, Chengcheng; Wu, Minghong

    2015-01-01

    In this study, a new europium complex of 4,4'-bis (1",1",1",2",2",3",3"-heptafluoro-4",6"- hexanedion-6"-yl)-o-terpheny-Eu(3+)-4,7-diphenyl-1,10-phenanthroline-2,9-dicarboxylic acid-(3-aminopropyl) trimethoxysilane (BHHT-Eu(3+)-DPPDA-APTMS) was prepared first. Then novel core-shell Ag@SiO2 nanoparticles with BHHT-Eu(3+)-DPPDA-APTMS doped in shell were synthesized by a facile water-in-oil microemulsion method. The properties of the prepared complex and nanoparticles, and the effect of metal enhanced fluorescence for the nanoparticles were investigated. The prepared nanopartilces exhibited intense fluorescence, uniform morphology and good water-solubility. The fluorescent intensities of silver core-present nanopartciles were significant higher than that of silver core-absent nanoparticles owing to the metal enhanced fluorescence of silver core. It is expectable that the as-prepared nanoparticles can serve as a potential fluorescent nanoprobe, applying in high sensitive biological and medical detections.

  16. Recent Progress in High Intensity Operation of the Fermilab Accelerator Complex

    SciTech Connect

    Convery, Mary E

    2016-10-05

    We report on the status of the Fermilab accelerator com-plex. Beam delivery to the neutrino experiments surpassed our goals for the past year. The Proton Improvement Plan is well underway with successful 15 Hz beam operation. Beam power of 700 kW to the NOvA experiment was demonstrated and will be routine in the next year. We are also preparing the Muon Campus to commission beam to the g-2 experiment.

  17. Core–shell Ag@SiO{sub 2} nanoparticles of different silica shell thicknesses: Preparation and their effects on photoluminescence of lanthanide complexes

    SciTech Connect

    Kang, Jie; Li, Yuan; Chen, Yingnan; Wang, Ailing; Yue, Bin; Qu, Yanrong; Zhao, Yongliang; Chu, Haibin

    2015-11-15

    Highlights: • Ag@SiO{sub 2} nanoparticles of different silica shell thicknesses were prepared via the Stöber process. • Sm and Dy complexes with benzoate, 1,10-phenanthroline and 2,2′-bipyridine were synthesized. • The complex-doped Ag@SiO{sub 2} composites show stronger luminescent intensities than pure complexes. • The luminescent intensities of the composites strongly depend on the SiO{sub 2} shell thickness. - Abstract: Three kinds of almost spherical core–shell Ag@SiO{sub 2} nanoparticles of different silica shell thicknesses (10, 25 and 80 nm) were prepared via the Stöber process. The Ag core nanoparticles were prepared by reducing silver nitrate with sodium citrate. The size, morphology and structure of core–shell Ag@SiO{sub 2} nanoparticles were characterized by transmission electron microscopy. Subsequently, eight kinds of lanthanide complexes with benzoate, 1,10-phenanthroline and 2,2′-bipyridine were synthesized. The composition of the lanthanide complexes was characterized by elemental analysis, IR and UV spectra. Finally, lanthanide complexes were attached to the surface of Ag@SiO{sub 2} nanoparticles to form lanthanide-complex-doped Ag@SiO{sub 2} nanocomposites. The results show that the complex-doped Ag@SiO{sub 2} nanocomposites display much stronger luminescence intensities than the lanthanide complexes. Furthermore, the luminescence intensities of the lanthanide-complex-doped Ag@SiO{sub 2} nanocomposites with SiO{sub 2} shell thickness of 25 nm are stronger than those of the nanocomposites with SiO{sub 2} shell thickness of 10 and 80 nm.

  18. Numerical simulations of Rayleigh-Taylor (RT) turbulence with complex acceleration history

    NASA Astrophysics Data System (ADS)

    Ramaprabhu, Praveen; Dimonte, Guy; Andrews, Malcolm

    2007-11-01

    Complex acceleration histories of an RT unstable interface are important in validating turbulent mix models. Of particular interest are alternating stages of acceleration and deceleration, since the the associated demixing is a discriminating test of such models. We have performed numerical simulations of a turbulent RT mixing layer subjected to two stages of acceleration separated by a stage of deceleration. The profile was chosen from earlier Linear Electric Motor experiments with which we compare our results. The acceleration phases produce classical RT unstable growth (t^2) with growth rates comparable to earlier results of turbulent RT simulations. The calculations are challenging as dominant bubbles become shredded as they reverse direction in response to the reversal in g, placing increased demands on numerical resolution. The shredding to small scales is accompanied by a peaking of the molecular mixing during the RT stable stage. In general, we find that simulations agree with experiments when initialized with broadband initial perturbations, but not for an annular shell. Other effects such as the presence of surface tension in the LEM experiments (but not in our simulations) further complicate this picture.

  19. Bacterial IgA protease-mediated degradation of agIgA1 and agIgA1 immune complexes as a potential therapy for IgA Nephropathy.

    PubMed

    Wang, Li; Li, Xueying; Shen, Hongchun; Mao, Nan; Wang, Honglian; Cui, Luke; Cheng, Yuan; Fan, Junming

    2016-08-03

    Mesangial deposition of aberrantly glycosylated IgA1 (agIgA1) and its immune complexes is a key pathogenic mechanism of IgA nephropathy (IgAN). However, treatment of IgAN remains ineffective. We report here that bacteria-derived IgA proteases are capable of degrading these pathogenic agIgA1 and derived immune complexes in vitro and in vivo. By screening 14 different bacterial strains (6 species), we found that 4 bacterial IgA proteases from H. influenzae, N. gonorrhoeae and N. meningitidis exhibited high cleaving activities on serum agIgA1 and artificial galactose-depleted IgA1 in vitro and the deposited agIgA1-containing immune complexes in the mesangium of renal biopsy from IgAN patients and in a passive mouse model of IgAN in vitro. In the modified mouse model of passive IgAN with abundant in situ mesangial deposition of the agIgA-IgG immune complexes, a single intravenous delivery of IgA protease from H. influenzae was able to effectively degrade the deposited agIgA-IgG immune complexes within the glomerulus, demonstrating a therapeutic potential for IgAN. In conclusion, the bacteria-derived IgA proteases are biologically active enzymes capable of cleaving the circulating agIgA and the deposited agIgA-IgG immune complexes within the kidney of IgAN. Thus, the use of such IgA proteases may represent a novel therapy for IgAN.

  20. Bacterial IgA protease-mediated degradation of agIgA1 and agIgA1 immune complexes as a potential therapy for IgA Nephropathy

    PubMed Central

    Wang, Li; Li, Xueying; Shen, Hongchun; Mao, Nan; Wang, Honglian; Cui, Luke; Cheng, Yuan; Fan, Junming

    2016-01-01

    Mesangial deposition of aberrantly glycosylated IgA1 (agIgA1) and its immune complexes is a key pathogenic mechanism of IgA nephropathy (IgAN). However, treatment of IgAN remains ineffective. We report here that bacteria-derived IgA proteases are capable of degrading these pathogenic agIgA1 and derived immune complexes in vitro and in vivo. By screening 14 different bacterial strains (6 species), we found that 4 bacterial IgA proteases from H. influenzae, N. gonorrhoeae and N. meningitidis exhibited high cleaving activities on serum agIgA1 and artificial galactose-depleted IgA1 in vitro and the deposited agIgA1-containing immune complexes in the mesangium of renal biopsy from IgAN patients and in a passive mouse model of IgAN in vitro. In the modified mouse model of passive IgAN with abundant in situ mesangial deposition of the agIgA-IgG immune complexes, a single intravenous delivery of IgA protease from H. influenzae was able to effectively degrade the deposited agIgA-IgG immune complexes within the glomerulus, demonstrating a therapeutic potential for IgAN. In conclusion, the bacteria-derived IgA proteases are biologically active enzymes capable of cleaving the circulating agIgA and the deposited agIgA-IgG immune complexes within the kidney of IgAN. Thus, the use of such IgA proteases may represent a novel therapy for IgAN. PMID:27485391

  1. Computational models reduce complexity and accelerate insight into cardiac signaling networks.

    PubMed

    Yang, Jason H; Saucerman, Jeffrey J

    2011-01-07

    Cardiac signaling networks exhibit considerable complexity in size and connectivity. The intrinsic complexity of these networks complicates the interpretation of experimental findings. This motivates new methods for investigating the mechanisms regulating cardiac signaling networks and the consequences these networks have on cardiac physiology and disease. Next-generation experimental techniques are also generating a wealth of genomic and proteomic data that can be difficult to analyze or interpret. Computational models are poised to play a key role in addressing these challenges. Computational models have a long history in contributing to the understanding of cardiac physiology and are useful for identifying biological mechanisms, inferring multiscale consequences to cell signaling activities and reducing the complexity of large data sets. Models also integrate well with experimental studies to explain experimental observations and generate new hypotheses. Here, we review the contributions computational modeling approaches have made to the analysis of cardiac signaling networks and forecast opportunities for computational models to accelerate cardiac signaling research.

  2. Reactivity towards nitriles, cyanamides, and carbodiimides of palladium complexes derived from benzyl alcohol. Synthesis of a mixed Pd2Ag complex.

    PubMed

    Fernández-Rodríguez, María-José; Martínez-Viviente, Eloísa; Vicente, José; Jones, Peter G

    2016-01-14

    The chelate complex [Pd(κ(2)-C,O-C6H4CH2O-2)(bpy)] () reacts with acetonitrile, cyanamides, or carbodiimides, in the presence of AgOTf (1 : 5 : 1 molar ratio) and residual water, to form complexes [Pd{κ(2)-C,N-C6H4{CH2OC([double bond, length as m-dash]NX)Y}-2}(bpy)](OTf), where X = H, Y = Me (), NMe2 (), NEt2 (), X = R, Y = NHR (R = (i)Pr (), Tol ()), as a result of the insertion of the unsaturated reagent into the O-Pd bond of and the protonation of one of the N atoms. In the absence of AgOTf the reaction of with TolN[double bond, length as m-dash]C[double bond, length as m-dash]NTol (Tol = p-Tolyl) results in the formation of the neutral complex [Pd{κ(2)-C,N-C6H4{CH2OC([double bond, length as m-dash]NTol)NTol}-2}(bpy)] (). Complexes and can be interconverted by deprotonation ( + KO(t)Bu) or protonation ( + KOTf + HOTf) reactions. When the reaction of with TolN[double bond, length as m-dash]C[double bond, length as m-dash]NTol in the presence of AgOTf is carried out in a 1 : 1 : 1 stoichiometric ratio, or for a short period of time, a mixture of and a mixed heterometallic Ag2Pd complex is obtained ( = [Ag(N-)2](OTf)). Complex is the major product when the AgOTf is added before the carbodiimide, and the reaction is stopped immediately. can also be obtained by reaction of with 0.5 equiv. of AgOTf. When complex [PdI(C6H4CH2OH-2)(bpy)] () reacts with (i)PrN[double bond, length as m-dash]C[double bond, length as m-dash]N(i)Pr in the presence of TlOTf, instead of AgOTf, a ca. 1 : 1 mixture of and [Pd{κ(2)-O,N-OCH2{C6H4{C([double bond, length as m-dash]NH(i)Pr)N(i)Pr}-2}}(bpy)](OTf) () forms. Complex is the result of the insertion of the carbodiimide into the C-Pd bond. Complexes have been extensively characterized by NMR spectroscopy, and the crystal structures of , , and ·2.5CHCl3·0.5Et2O have been determined by X-ray diffraction studies.

  3. Cu(I) and Ag(I) complexes of 7,10-bis-N-heterocycle-diazafluoranthenes: programmed molecular grids?

    PubMed

    Rahanyan, Nelli; Duttwyler, Simon; Linden, Anthony; Baldridge, Kim K; Siegel, Jay S

    2014-07-28

    Reactions of 7,10-disubstituted diazafluoranthene derivatives with three different silver(I) salts AgX (X = [PF6](-), [SbF6](-), [CB11HCl11](-)) and [Cu(CH3CN)4]PF6 afforded complexes exhibiting five different motifs. The crystal structures of the free ligands and nine new complexes from this series of reactions are reported. The use of 2,5-di-tert-butyl-7,10-di(pyridin-2-yl)-8,9-diazafluoranthene as a ligand leads to the formation of the tetranuclear compounds [Ag4(C32H30N4)4][PF6]4·3C6H6·4MeCN, [Ag4(C32H30N4)4][SbF6]4·4C5H12 and [Cu4(C32H30N4)4][PF6]4·8C3H6O, which exhibit "propeller" and saddle-type geometry, respectively, as well as a dinuclear complex [Ag2(C32H30N4)2][CHB11Cl11]2·4C6H4Cl2·CH2Cl2. The reactions involving the less sterically hindered 2,5-di-tert-butyl-7,10-di-(pyrimidin-2-yl)-8,9-diazafluoranthene and 2,5-di-tert-butyl-7,10-di(thiazol-2-yl)-8,9-diazafluoranthene afforded crystals of the dinuclear complexes [Ag2(C30H28N6)2][PF6]2·0.5CH2Cl2·0.5C6H5Cl·0.5C6H12, [Ag2(C30H28N6)2][SbF6]2·C3H6O·0.5C6H14·0.5C6H6, the polymeric species [Ag2(C28H26N4S2)2]n·2n[PF6]n·nC3H6O and the tetranuclear compounds [Cu4(C26H25N4S2)4][PF6]4·2CHCl3·2C3H6O and [Cu4(C30H28N6)4][PF6]4·2.17H2O, which possess saddle and grid-like architectures, respectively. Conformational analysis of the free ligands showed that they exhibit N-C-C-N torsion angles ranging from syn clinal (58°) to fully anti-periplanar conformations; the syn clinal conformation dominates in the complexes. The relative energies of the possible structural conformations of the synthesized ligands, as well as of oxazole disubstituted diazafluoranthenes, were calculated using density functional theory at the B97D/Def2-TZVPP level of theory.

  4. 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

  5. Materials irradiation facilities at the high-power Swiss proton accelerator complex

    NASA Astrophysics Data System (ADS)

    Wagner, Werner; Dai, Yong; Glasbrenner, Heike; Aebersold, Hans-Ulrich

    2007-04-01

    Within the Swiss proton accelerator complex at the Paul-Scherrer-Institute (PSI), several irradiation facilities are operated for investigation of materials behavior under high-dose irradiation conditions as well as for neutron activation analysis and isotope production. In LiSoR (liquid solid reaction), a liquid metal loop connected to the 72 MeV proton accelerator Injector 1, steel samples are irradiated while being in contact with flowing lead-bismuth-eutectic (LBE) at elevated temperatures and under tensile stress. In the spallation neutron source SINQ, the STIP program (SINQ Target Irradiation Program) allows materials irradiation under realistic spallation conditions, i.e. in a mixed spectrum of 570 MeV protons and spallation neutrons. Hundreds of samples, mainly austenitic and ferritic-martensitic steels such as 316L, T91 or F82H, were irradiated to doses up to 20 dpa as part of STIP. These also included steel samples in contact with liquid Hg and liquid LBE. MEGAPIE (MEGAwatt PIlot Experiment), a liquid metal target employing LBE, operated in SINQ during the second half of 2006, can be taken as a materials irradiation facility on its own. Adjacent to the target position, SINQ houses a neutron irradiation rabbit system serving activation analysis and isotope production.

  6. Accelerating the Mining of Influential Nodes in Complex Networks through Community Detection

    SciTech Connect

    Halappanavar, Mahantesh; Sathanur, Arun V.; Nandi, Apurba

    2016-05-31

    Computing the set of influential nodes with a given size to ensure maximal spread of influence on a complex network is a challenging problem impacting multiple applications. A rigorous approach to influence maximization involves utilization of optimization routines that comes with a high computational cost. In this work, we propose to exploit the existence of communities in complex networks to accelerate the mining of influential seeds. We provide intuitive reasoning to explain why our approach should be able to provide speedups without significantly degrading the extent of the spread of influence when compared to the case of influence maximization without using the community information. Additionally, we have parallelized the complete workflow by leveraging an existing parallel implementation of the Louvain community detection algorithm. We then conduct a series of experiments on a dataset with three representative graphs to first verify our implementation and then demonstrate the speedups. Our method achieves speedups ranging from 3x - 28x for graphs with small number of communities while nearly matching or even exceeding the activation performance on the entire graph. Complexity analysis reveals that dramatic speedups are possible for larger graphs that contain a correspondingly larger number of communities. In addition to the speedups obtained from the utilization of the community structure, scalability results show up to 6.3x speedup on 20 cores relative to the baseline run on 2 cores. Finally, current limitations of the approach are outlined along with the planned next steps.

  7. Accelerated acidification by inoculation with a microbial consortia in a complex open environment.

    PubMed

    Yu, Jiadong; Zhao, Ye; Liu, Bin; Zhao, Yubin; Wu, Jingwei; Yuan, Xufeng; Zhu, Wanbin; Cui, Zongjun

    2016-09-01

    Bioaugmentation using microbial consortia is helpful in some anaerobic digestion (AD) systems, but accelerated acidification to produce methane has not been performed effectively with corn stalks and cow dung. In this study, the thermophilic microbial consortia MC1 was inoculated into a complex open environment (unsterilized and sterilized systems) to evaluate the feasibility of bioaugmentation to improve acidification efficiency. The results indicated that MC1 itself degraded lignocellulose efficiently, and accumulated more organic acids within 3days. Similar trends were also observed in the unsterilized system, where the hemicellulose degradation rate and organic acid concentrations increased significantly by two-fold and 20.1% (P<0.05), respectively, and clearly reduced the loss of product. Microbial composition did not change obviously after inoculating MC1, but the abundance of members of MC1, such as Bacillus and Clostridium, increased clearly on day 3. Finally, the acidogenic fluid improved methane yield significantly (P<0.05) via bioaugmentation.

  8. The complex nature of storm-time ion dynamics: Transport and local acceleration

    NASA Astrophysics Data System (ADS)

    Denton, M. H.; Reeves, G. E.; Thomsen, M. F.; Henderson, M. G.; Friedel, R. H. W.; Larsen, B.; Skoug, R. M.; Funsten, H. O.; Spence, H. E.; Kletzing, C. A.

    2016-10-01

    Data from the Van Allen Probes Helium, Oxygen, Proton, and Electron (HOPE) spectrometers reveal hitherto unresolved spatial structure and dynamics in ion populations. Complex regions of O+ dominance, at energies from a few eV to >10 keV, are observed throughout the magnetosphere. Isolated regions on the dayside that are rich in energetic O+ might easily be interpreted as strong energization of ionospheric plasma. We demonstrate, however, that both the energy spectrum and the limited magnetic local time extent of these features can be explained by energy-dependent drift of particles injected on the nightside 24 h earlier. Particle tracing simulations show that the energetic O+ can originate in the magnetotail, not in the ionosphere. Enhanced wave activity is colocated with the heavy ion-rich plasma, and we further conclude that the waves were not a source of free energy for accelerating ionospheric plasma but rather the consequence of the arrival of substorm-injected plasma.

  9. Metallacycles or coexistence of isomeric metallacycle and chain: Anion-dependent luminescent Ag complexes of a flexible diaminotriazine-imidazole ligand

    NASA Astrophysics Data System (ADS)

    Mei, Hong-Xin; Zhang, Ting; Wang, Dan-Feng; Huang, Rong-Bin; Zheng, Lan-Sun

    2015-07-01

    Reaction of a flexible ligand 2,4-diamino-6-[2-(2-methyl-1-imidazolyl) ethyl]-1,3,5-triazine (L) with Ag(I) in the presence of different counteranions afforded five complexes, namely, 2[Agn(L)n(NH3)n] · n[Ag2(L)2(NH3)2] · 2n(nds) (1, H2nds = 1,5-naphthalenedisulfonic acid), 2[Agn(L)n] · n[Ag2(L)2(CF3CO2)2] · nCF3CO2 (2), [Ag2(L)2(NH3)2] · 2(ClO4) (3), [Ag2(L)2] · 2(NO3) (4), [Ag2(L)2] · 2(ClO3) (5), which were characterized by element analysis, IR, PXRD and X-ray single-crystal diffraction. Structural analysis reveals that the L ligand take the same bidentate coordination mode in these complexes. The nds anion and the CF3 CO2- anion lead to the coexistence of isomeric metallacycle and helical chain (ring-opening isomers) in the crystals of 1 and 2, while ClO4-, NO3- and ClO3- anions afford dimeric metallacycles in complexes 3-5. Moreover, thermal gravity analysis (TGA) and emissive behaviors of these complexes were investigated.

  10. A Complex of Htm1 and the Oxidoreductase Pdi1 Accelerates Degradation of Misfolded Glycoproteins.

    PubMed

    Pfeiffer, Anett; Stephanowitz, Heike; Krause, Eberhard; Volkwein, Corinna; Hirsch, Christian; Jarosch, Ernst; Sommer, Thomas

    2016-06-03

    A quality control system in the endoplasmic reticulum (ER) efficiently discriminates polypeptides that are in the process of productive folding from conformers that are trapped in an aberrant state. Only the latter are transported into the cytoplasm and degraded in a process termed ER-associated protein degradation (ERAD). In the ER, an enzymatic cascade generates a specific N-glycan structure of seven mannosyl and two N-acetylglucosamine residues (Man7GlcNAc2) on misfolded glycoproteins to facilitate their disposal. We show that a complex encompassing the yeast lectin-like protein Htm1 and the oxidoreductase Pdi1 converts Man8GlcNAc2 on glycoproteins into the Man7GlcNAc2 signal. In vitro the Htm1-Pdi1 complex processes both unfolded and native proteins albeit with a preference for the former. In vivo, elevated expression of HTM1 causes glycan trimming on misfolded and folded proteins, but only degradation of the non-native species is accelerated. Thus, modification with a Man7GlcNAc2 structure does not inevitably commit a protein for ER-associated protein degradation. The function of Htm1 in ERAD relies on its association with Pdi1, which appears to regulate the access to substrates. Our data support a model in which the balanced activities of Pdi1 and Htm1 are crucial determinants for the efficient removal of misfolded secretory glycoproteins.

  11. Desulfinylation of Ag(I) Sulfinyl Mesoionic Carbenes: Preparation of C-Unsubstituted Au(I)-1,2,3-Triazole Carbene Complexes.

    PubMed

    Frutos, María; Ortuño, Manuel A; Lledos, Agustí; Viso, Alma; Fernández de la Pradilla, Roberto; de la Torre, María C; Sierra, Miguel A; Gornitzka, Heinz; Hemmert, Catherine

    2017-02-17

    New and well-characterized Ag-bis(1,2,3-triazolylidene) complexes having enantiopure (S)-sulfoxides upon sequential treatment with alcohols and Au(I) form separable mixtures of regioisomeric C-unsubstituted Au-1,2,3-triazolylidene complexes. Mechanistic studies and DFT calculations support a desulfinylation process for in situ generated free triazolylidene salts.

  12. Accelerated failure time models for semi-competing risks data in the presence of complex censoring.

    PubMed

    Lee, Kyu Ha; Rondeau, Virginie; Haneuse, Sebastien

    2017-04-10

    Statistical analyses that investigate risk factors for Alzheimer's disease (AD) are often subject to a number of challenges. Some of these challenges arise due to practical considerations regarding data collection such that the observation of AD events is subject to complex censoring including left-truncation and either interval or right-censoring. Additional challenges arise due to the fact that study participants under investigation are often subject to competing forces, most notably death, that may not be independent of AD. Towards resolving the latter, researchers may choose to embed the study of AD within the "semi-competing risks" framework for which the recent statistical literature has seen a number of advances including for the so-called illness-death model. To the best of our knowledge, however, the semi-competing risks literature has not fully considered analyses in contexts with complex censoring, as in studies of AD. This is particularly the case when interest lies with the accelerated failure time (AFT) model, an alternative to the traditional multiplicative Cox model that places emphasis away from the hazard function. In this article, we outline a new Bayesian framework for estimation/inference of an AFT illness-death model for semi-competing risks data subject to complex censoring. An efficient computational algorithm that gives researchers the flexibility to adopt either a fully parametric or a semi-parametric model specification is developed and implemented. The proposed methods are motivated by and illustrated with an analysis of data from the Adult Changes in Thought study, an on-going community-based prospective study of incident AD in western Washington State.

  13. Comparative modular analysis of two complex sulfosalt structures: sterryite, Cu(Ag,Cu)3Pb19(Sb,As)22(As-As)S56, and parasterryite, Ag4Pb20(Sb,As)24S58.

    PubMed

    Moëlo, Yves; Guillot-Deudon, Catherine; Evain, Michel; Orlandi, Paolo; Biagioni, Cristian

    2012-10-01

    The crystal structures of two very close, but distinct complex minerals of the lead sulfosalt group have been solved: sterryite, Cu(Ag,Cu)(3)Pb(19)(Sb,As)(22)(As-As)S(56), and parasterryite, Ag(4)Pb(20)(Sb,As)(24)S(58). They are analyzed and compared according to modular analysis. The fundamental building block is a complex column centred on a Pb(6)S(12) triangular prismatic core, with two additional long and short arms. The main chemical and topological differences relate to the short arm, which induces a relative a/4 shift (~2 Å along the elongation parameter) of the constitutive rod layers, as illustrated by distinct cell settings within the same space group (P2(1)/n and P2(1)/c, respectively). Selection of the shortest (i.e. strongest) (Sb,As)-S bonds permitted to enhance the polymeric organization of (Sb,As) atoms with triangular pyramidal coordination. These two quasi-homeotypic structures are expanded derivatives of owyheeite, Ag(3)Pb(10)Sb(11)S(28). The hierarchy of organization levels from zero- to three-dimensional entities is subordinated to building operators, which appear as the driving force for the construction of such complex structures. Minor cations (Ag, Cu) or the As-As pair in sterryite secure the final locking, which favours the formation of one or the other compound.

  14. Uniform Plasma Etching of Complex Shaped Three Dimensional Niobium Structures for Particle Accelerators

    NASA Astrophysics Data System (ADS)

    Upadhyay, Janardan; Im, Do; Peshl, Jeremy; Popovic, Svetozar; Vuskovic, Lepsha; Phillips, Larry; Valente-Felliciano, Anne-Marie

    2014-10-01

    Complex shaped three dimensional niobium structures are used in particle accelerators as super conducting radio frequency (SRF) cavities. The inner surfaces of these structures have to be chemically etched for better performance, as SRF performance parameters are very sensitive to their properties. Plasma etching of inner surface of three dimensional niobium structures has not been reported even though plasma etching of niobium has been reported earlier for Josephson junction and other applications. We are proposing an RF capacitively coupled coaxial (ccp) plasma etching method for nano machining of niobium structures for SRF applications. We are using gas mixture of Argon and Chlorine. We report the effects of the pressure, RF power, gas concentration, shape and size of the inner electrode, temperature of the structure, DC bias voltage and residence time on the etch rate of the niobium. We also show the method to reduce the asymmetry effect in coaxial ccp by changing the shape of the inner electrode in cylindrical structure, as well as a method to overcome the severe loading effect in etching of 3D structures for uniform mass removal purpose. Supported by DOE under Grant No. DE-SC0007879. J.U. acknowledges support by JSA/DOE via DE-AC05-06OR23177.

  15. A new slip stacking RF system for a twofold power upgrade of Fermilab's Accelerator Complex

    SciTech Connect

    Madrak, Robyn

    2014-05-15

    Fermilab's Accelerator Complex has been recently upgraded, in order to increase the 120 GeV proton beam power on target from about 400 kW to over 700 kW for NOvA and other future intensity frontier experiments. One of the key ingredients of the upgrade is the offloading of some Main Injector synchrotron operations - beam injection and RF manipulation called ''slip stacking'' - to the 8GeV Recycler Ring, which had until recently been used only for low-intensity antiproton storage and cooling. This required construction of two new 53 MHz RF systems for the slip-stacking manipulations. The cavities operate simultaneously at Vpeak ≲150 kV, but at slightly different frequencies (Δf=1260 Hz). Their installation was completed in September 2013. This article describes the novel solutions used in the design of the new cavities, their tuning system, and the associated high power RF system. First results showing effective operation of the RF system, beam capture and successful slip-stacking in the Recycler Ring are presented.

  16. Applying accelerator mass spectrometry for low-level detection of complex engineered nanoparticles in biological media.

    PubMed

    Wang, Binghui; Jackson, George S; Yokel, Robert A; Grulke, Eric A

    2014-08-01

    Complex engineered nanoparticles (CENPs), which have different core and surface components, are being developed for medicinal, pharmaceutical and industrial applications. One of the key challenges for environmental health and safety assessments of CENPs is to identify and quantity their transformations in biological environments. This study reports the effects of in vivo exposure of citrate-coated nanoalumina with different rare isotope labels on each component. This CENP was dosed to the rat and accelerator mass spectrometry (AMS) was used to quantify (26)Al, (14)C, and their ratio in the dosing material and tissue samples. For CENPs detected in the liver, the rare isotope ratio, (14)C/(26)Al, was 87% of the dosing material's ratio. The citrate coating on the nanoalumina in the liver was stable or, if it degraded, its metabolites were incorporated with nearby tissues. However, in brain and bone where little alumina was detected, the rare isotope ratio greatly exceeded that of the dosing material. Therefore, in the animal, citrate dissociated from CENPs and redistributed to brain and bone. Tracking both the core and surface components by AMS presents a new approach for characterizing transformations of CENPs components in biological milieu or environments.

  17. Mitochondrial Complex I Deficiency Increases Protein Acetylation and Accelerates Heart Failure

    PubMed Central

    Karamanlidis, Georgios; Lee, Chi Fung; Garcia-Menendez, Lorena; Kolwicz, Stephen C.; Suthammarak, Wichit; Gong, Guohua; Sedensky, Margaret M.; Morgan, Philip G.; Wang, Wang; Tian, Rong

    2013-01-01

    Summary Mitochondrial respiratory dysfunction is linked to the pathogenesis of multiple diseases including heart failure but the specific mechanisms for this link remain largely elusive. We modeled the impairment of mitochondrial respiration by inactivation of the Ndufs4 gene, a protein critical for Complex I (C-I) assembly, in the mouse heart (cKO). While C-I supported respiration decreased by >40%, the cKO mice maintained normal cardiac function in vivo and high-energy phosphate content in isolated perfused hearts. However, the cKO mice developed accelerated heart failure after pressure overload or repeated pregnancy. Decreased NAD+/NADH ratio by C-I deficiency inhibited Sirt3 activity, leading to increase in protein acetylation, and sensitization of the permeability transition in mitochondria (mPTP). NAD+ precursor supplementation to cKO mice partially normalized the NAD+/NADH ratio, protein acetylation and mPTP sensitivity. These findings describe a mechanism connecting mitochondrial dysfunction to the susceptibility to diseases and propose a potential therapeutic target. PMID:23931755

  18. An application of Ag(III) complex chemiluminescence system for the determination of enoxacin in capsule and biological fluid.

    PubMed

    Chen, Peiyun; Sun, Hanwen

    2010-01-01

    Ag(III) complex chemiluminescence (CL) system was applied for the determination of enoxacin (ENX). The CL conditions of [Ag(HIO(6))(2)](5-)-H(2)SO(4)-ENX systems without any luminescence reagent were investigated and optimized. Under the optimized conditions, the CL intensity was proportional to the concentration of ENX in the range from 6.6 × 10(-5) to 3.3 × 10(-3) g/L. The limit of detection (s/n = 3) was 2.0 × 10(-5) g/L. The recovery of ENX from the spiked pharmaceutical preparations was in the range of 82.9-108% with a relative standard deviation of 1.9-3.0%. For spiked serum and urine samples the recovery of ENX was in the range of 83.7-110% with a relative standard deviation of 1.1-2.8%. The proposed method was applied successfully to the determination of the drug in capsule, serum and urine samples.

  19. Ligand field photofragmentation spectroscopy of [Ag(L)N]2+ complexes in the gas phase: experiment and theory.

    PubMed

    Guan, Jingang; Puskar, Ljiljana; Esplugas, Ricardo O; Cox, Hazel; Stace, Anthony J

    2007-08-14

    Experiments have been undertaken to record photofragmentation spectra from a series of [Ag(L)N]2+ complexes in the gas phase. Spectra have been obtained for silver(II) complexed with the ligands (L): acetone, 2-pentanone, methyl-vinyl ketone, pyridine, and 4-methyl pyridine (4-picoline) with N in the range of 4-7. A second series of experiments using 1,1,1,3-fluoroacetone, acetonitrile, and CO2 as ligands failed to show any evidence of photofragmentation. Interpretation of the experimental data has come from time-dependent density functional theory (TDDFT), which very successfully accounts for trends in the spectra in terms of subtle differences in the properties of the ligands. Taking a sample of three ligands, acetone, pyridine, and acetonitrile, the calculations show all the spectral transitions to involve ligand-to-metal charge transfer, and that wavelength differences (or lack of spectra) arise from small changes in the energies of the molecular orbitals concerned. The calculations account for an absence in the spectra of any effects due to Jahn-Teller distortion, and they also reveal structural differences between complexes where the coordinating atom is either oxygen or nitrogen that have implications for the stability of silver(II) compounds. Where possible, comparisons have also been made with the physical properties of condensed phase silver(II) complexes.

  20. Microstructural studies of AgNbO{sub 3} ceramic by using complex impedance spectroscopy

    SciTech Connect

    Gangaprasad, K.; Rao, T. Durga; Niranjan, Manish K.; Asthana, Saket

    2015-06-24

    Lead-free piezoelectric silver niobate ceramic was synthesized by conventional solid state route. Room temperature X-ray diffraction pattern revealed that the sample crystallizes in single phase orthorhombic perovskite structure. Scanning electron micrographs of AgNbO{sub 3} ceramic showed that the average grain size is in the range 2–3 µm. The electrical properties were investigated by using impedance spectroscopy. Appearance of single semicircular arc in the Nyquist plot indicated the presence of grain contribution in the sample. Single RC parallel circuit model was employed to extract bulk capacitance (C{sub b}), resistance (R{sub b}) and electrical conductivity (σ{sub b}). The activation energy calculated from impedance and modulus data indicate that same types of charge carriers (oxygen vacancy movements) are responsible for conduction and relaxation.

  1. Mapping of second-nearest-neighbor fluoride ions of orthorhombic Gd 3+-Ag + complexes in CaF 2

    NASA Astrophysics Data System (ADS)

    Nakata, R.; Den Hartog, H. W.

    The ENDOR technique is applied to determine the positions of 24 second-nearest-neighbor F - ions around an orthorhombic Gd 3+-Ag + complex in CaF 2 crystals. Experimental ENDOR data of the second-nearest-neighbor F - ions are analyzed by using the usual spin Hamiltonian and a least-squares fitting method. The best fits of the experimental results give superhyperfine (shf) constants and the F - directions ( K, L, M) with respect to the Gd 3+ ion, from which the distance between the second-nearest-neighbor F - ion and the Gd 3+ ion is determined by assuming that the hyperfine interaction is due to the classical dipole-dipole interaction. The displacements of the F - ions are estimated and compared with the theoretical values calculated by Bijvank and den Hartog on the basis of a polarizable point charge model.

  2. Complexes of Ag(I), Hg(I) and Hg(II) with multidentate pyrazolyl-pyridine ligands: From mononuclear complexes to coordination polymers via helicates, a mesocate, a cage and a catenate.

    PubMed

    Argent, Stephen P; Adams, Harry; Riis-Johannessen, Thomas; Jeffery, John C; Harding, Lindsay P; Clegg, William; Harrington, Ross W; Ward, Michael D

    2006-11-14

    The coordination chemistry of a series of di- and tri-nucleating ligands with Ag(I), Hg(I) and Hg(II) has been investigated. Most of the ligands contain two or three N,N'-bidentate chelating pyrazolyl-pyridine units pendant from a central aromatic spacer; one contains three binding sites (2 + 3 + 2-dentate) in a linear sequence. A series of thirteen complexes has been structurally characterised displaying a wide range of structural types. Bis-bidentate bridging ligands react with Ag(I) to give complexes in which Ag(I) is four-coordinate from two bidentate donors, but the complexes can take the form of one-dimensional coordination polymers, or dinuclear complexes (mesocate or helicate). A tris-bidentate triangular ligand forms a complicated two-dimensional coordination network with Ag(I) in which Ag...Ag contacts, as well as metal-ligand coordination bonds, play a significant role. Three dinuclear Hg(I) complexes were isolated which contain an {Hg2}2+ metal-metal bonded core bound to a single bis-bidentate ligand which can span both metal ions. Also characterised were a series of Hg(II) complexes comprising a simple mononuclear four-coordinate Hg(II) complex, a tetrahedral Hg(II)4 cage which incorporates a counter-ion in its central cavity, a trinuclear double helicate, and a trinuclear catenated structure in which two long ligands have spontaneously formed interlocked metallomacrocyclic rings thanks to cyclometallation of two of the Hg(II) centres.

  3. Single nucleotide polymorphism in Ag85 genes of Mycobacterium tuberculosis complex: analysis of 178 clinical isolates from China and 13 BCG strains.

    PubMed

    Jiang, Yi; Liu, Haican; Li, Machao; Li, Guilian; Pang, Hui; Dou, Xiangfeng; Zhao, Xiuqin; Wan, Kanglin

    2015-01-01

    Host immune pressure and associated immune evasion of pathogenic bacteria are key features of host-pathogen co-evolution. Human T-cell epitopes of Mycobacterium tuberculosis (M. tuberculosis) were evolutionarily hyperconserved and thus it was deduced that M. tuberculosis lacks antigenic variation and immune evasion. However, in our previous studies, proteins MPT64, PstS1, Rv0309 and Rv2945c all harbored higher numbers of amino acid substitutions in their T cell epitopes, which suggests their roles in ongoing immune evasion. Here, we used the same set of 180 clinical M. tuberculosis complex (MTBC) isolates from China, amplified the genes encoding Ag85 complex, and compared the sequences. The results showed that Ag85 were hyperconserved in T/B cell epitopes and the genes were more likely to be under purifying selection. The divergence of host immune selection on different proteins may result from different function of the proteins. In addition, A312G of Ag85A and T418C of Ag85B may represent special mutations in BCG strains, which may be used to differentiate M.bovis and BCG strains from MTB strains. Also, C714A in Ag85B seems to be a valuable phylogenetic marker for Beijing strains.

  4. Molecular structure, spectroscopic properties, NLO and NBO analysis of 3,4-Lutidine and [Ag(3,4-Lutidine)2NO3] complex

    NASA Astrophysics Data System (ADS)

    Soliman, Saied M.

    2013-09-01

    The molecular structure and electronic properties of 3,4-Lutidine (34Lut) and its silver(I) complex; [Ag(34Lut)2NO3] have been reported. The geometry of the titled compounds was optimized using HF and DFT/B3LYP methods. The calculations predicted a distorted tetrahedral coordination geometry around the Ag(I) ion. The complete vibrational assignments of the 34Lut and [Ag(34Lut)2NO3] complex have been made on the basis of Total Energy Distribution (TED). The vibrational frequencies calculated using DFT/B3LYP method showed better agreement with the experimental values compared to HF method. For [Ag(34Lut)2NO3] complex, the calculations predicted the presence of intramolecular CH⋯O interactions between the oxygen of the nitrate and the neighboring hydrogen atoms of the coordinated 34Lut which is confirmed by the TED analysis of the CH stretching modes. Unexpected blue shift is predicted for the CH stretching modes involved in such interactions. A study on the electronic properties, such as HOMO and LUMO energies as well as the molecular electrostatic potential (MEP) was performed using the same level of theory. Natural charges and natural bond orbital (NBO) analyses of the studied molecules were also calculated and interpreted. The dipole moment, linear polarizability and first hyperpolarizability values were used to describe the NLO properties of the studied compounds.

  5. Ab initio nonadiabatic dynamics of multichromophore complexes: a scalable graphical-processing-unit-accelerated exciton framework.

    PubMed

    Sisto, Aaron; Glowacki, David R; Martinez, Todd J

    2014-09-16

    ("fragmenting") a molecular system and then stitching it back together. In this Account, we address both of these problems, the first by using graphical processing units (GPUs) and electronic structure algorithms tuned for these architectures and the second by using an exciton model as a framework in which to stitch together the solutions of the smaller problems. The multitiered parallel framework outlined here is aimed at nonadiabatic dynamics simulations on large supramolecular multichromophoric complexes in full atomistic detail. In this framework, the lowest tier of parallelism involves GPU-accelerated electronic structure theory calculations, for which we summarize recent progress in parallelizing the computation and use of electron repulsion integrals (ERIs), which are the major computational bottleneck in both density functional theory (DFT) and time-dependent density functional theory (TDDFT). The topmost tier of parallelism relies on a distributed memory framework, in which we build an exciton model that couples chromophoric units. Combining these multiple levels of parallelism allows access to ground and excited state dynamics for large multichromophoric assemblies. The parallel excitonic framework is in good agreement with much more computationally demanding TDDFT calculations of the full assembly.

  6. 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.

  7. Synthesis, characterization, microbiological evaluation, genotoxicity and synergism tests of new nano silver complexes with sulfamoxole: X-ray diffraction of [Ag2(SMX)2]·DMSO.

    PubMed

    Velluti, Francesca; Mosconi, Natalia; Acevedo, Ana; Borthagaray, Graciela; Castiglioni, Jorge; Faccio, Ricardo; Back, Davi Fernando; Moyna, Guillermo; Rizzotto, Marcela; Torre, María H

    2014-12-01

    The synthesis and microbiological evaluation of two new Ag(I) complexes with sulfamoxole (SMX), [Ag2(SMX)2]·H2O and [Ag4(SCN)3(SMX)]·H2O are described. Both were characterized by elemental analysis, thermogravimetry, powder and single crystal X-ray diffraction, NMR, Raman and experimental and theoretical IR spectroscopies. Their antibacterial and antifungal properties were evaluated by agar and broth dilution assays, respectively. In addition, synergism tests for Pseudomonas aeruginosa were performed, and genotoxicity studies were carried out employing the Allium cepa test. Both complexes displayed good activity against Escherichia coli, Staphylococcus aureus, P. aeruginosa, and 10 fungi strains, with lower minimum inhibitory concentrations (MICs) than that of free SMX in all cases. The nanometrical crystallite particle size determined from XRPD, DLS and TEM might explain the good microbiological activity in spite of the low solubility of both complexes. The fractional inhibitory concentration (FIC) calculated from the P. aeruginosa test data indicated that the activity of the complexes is not due to synergism of the free components in the concentration ratios studied. Moreover, none of the complexes displayed cytotoxic effects on onions in the concentration range tested, and chromosome aberrations were not observed.

  8. Significant contribution of subtype G to HIV-1 genetic complexity in Nigeria identified by a newly developed subtyping assay specific for subtype G and CRF02_AG

    PubMed Central

    Heipertz, Richard A.; Ayemoba, Ojor; Sanders-Buell, Eric; Poltavee, Kultida; Pham, Phuc; Kijak, Gustavo H.; Lei, Esther; Bose, Meera; Howell, Shana; O'Sullivan, Anne Marie; Bates, Adam; Cervenka, Taylor; Kuroiwa, Janelle; Akintunde, Akindiran; Ibezim, Onyekachukwu; Alabi, Abraham; Okoye, Obumneke; Manak, Mark; Malia, Jennifer; Peel, Sheila; Maisaka, Mohammed; Singer, Darrell; O’Connell, Robert J.; Robb, Merlin L.; Kim, Jerome H.; Michael, Nelson L.; Njoku, Ogbonnaya; Tovanabutra, Sodsai

    2016-01-01

    Abstract While abundant sequence information is available from human immunodeficiency virus type 1 (HIV-1) subtypes A, B, C and CRF01_AE for HIV-1 vaccine design, sequences from West Africa are less represented. We sought to augment our understanding of HIV-1 variants circulating in 6 Nigerian cities as a step to subsequent HIV-1 vaccine development. The G/CRF02_AG multi-region hybridization assay (MHA) was developed to differentiate subtype G, CRF02_AG and their recombinants from other subtypes based on 7 HIV-1 segments. Plasma from 224 HIV-1 infected volunteers enrolled in a cohort examining HIV-1 prevalence, risk factor, and subtype from Makurdi (30), Abuja (18), Enugu (11), Kaduna (12), Tafa (95), and Ojo/Lagos (58) was analyzed using MHA. HIV-1 genomes from 42 samples were sequenced to validate the MHA and fully explore the recombinant structure of G and CRF02_AG variants. The sensitivity and specificity of MHA varied between 73–100% and 90–100%, respectively. The subtype distribution as identified by MHA among 224 samples revealed 38% CRF02_AG, 28% G, and 26% G/CRF02_AG recombinants while 8% remained nontypeable strains. In envelope (env) gp120, 38.84% of the samples reacted to a G probe while 31.25% reacted to a CRF02 (subtype A) probe. Full genome characterization of 42 sequences revealed the complexity of Nigerian HIV-1 variants. CRF02_AG, subtype G, and their recombinants were the major circulating HIV-1 variants in 6 Nigerian cities. High proportions of samples reacted to a G probe in env gp120 confirms that subtype G infections are abundant and should be considered in strategies for global HIV-1 vaccine development. PMID:27512845

  9. PERFORMANCE OF THE AGS TRANSITION JUMP SYSTEM.

    SciTech Connect

    AHRENS,L.A.; BRENNAN,J.M.; GLENN,J.W.; ROSER,T.; VAN ASSELT,W.K.

    1999-03-29

    The transition jump system has been indispensable to the high intensity proton operation of the AGS complex. Nevertheless, transition crossing remains one of the major hurdles as the accelerator complex intensity is pushed upward. To enhance the performance of the system ''quadrupole pumping'' in the Booster is used to minimize the necessary longitudinal dilution of the beam on the AGS injection porch. During the transition jump sextupole correctors at strategic locations are pulsed to minimize the effects of the chromatic non-linearity of the jump system. The available instrumentation for diagnosing the performance of the system will be described, along with installed hardware to counter the non-linear effects of the transition jump system.

  10. Tsallis entropy and complexity theory in the understanding of physics of precursory accelerating seismicity.

    NASA Astrophysics Data System (ADS)

    Vallianatos, Filippos; Chatzopoulos, George

    2014-05-01

    Strong observational indications support the hypothesis that many large earthquakes are preceded by accelerating seismic release rates which described by a power law time to failure relation. In the present work, a unified theoretical framework is discussed based on the ideas of non-extensive statistical physics along with fundamental principles of physics such as the energy conservation in a faulted crustal volume undergoing stress loading. We derive the time-to-failure power-law of: a) cumulative number of earthquakes, b) cumulative Benioff strain and c) cumulative energy released in a fault system that obeys a hierarchical distribution law extracted from Tsallis entropy. Considering the analytic conditions near the time of failure, we derive from first principles the time-to-failure power-law and show that a common critical exponent m(q) exists, which is a function of the non-extensive entropic parameter q. We conclude that the cumulative precursory parameters are function of the energy supplied to the system and the size of the precursory volume. In addition the q-exponential distribution which describes the fault system is a crucial factor on the appearance of power-law acceleration in the seismicity. Our results based on Tsallis entropy and the energy conservation gives a new view on the empirical laws derived by other researchers. Examples and applications of this technique to observations of accelerating seismicity will also be presented and discussed. This work was implemented through the project IMPACT-ARC in the framework of action "ARCHIMEDES III-Support of Research Teams at TEI of Crete" (MIS380353) of the Operational Program "Education and Lifelong Learning" and is co-financed by the European Union (European Social Fund) and Greek national funds

  11. Geometries of H2S⋯MI (M = Cu, Ag, Au) complexes studied by rotational spectroscopy: The effect of the metal atom

    NASA Astrophysics Data System (ADS)

    Medcraft, Chris; Bittner, Dror M.; Tew, David P.; Walker, Nicholas R.; Legon, Anthony C.

    2016-11-01

    Complexes formed between H2S and each of CuI, AgI, and AuI have been isolated and structurally characterised in the gas phase. The H2S⋯ MI complexes (where M is the metal atom) are generated through laser vaporisation of a metal rod in the presence of a low concentration of H2S and CF3I in a buffer gas of argon undergoing supersonic expansion. The microwave spectra of six isotopologues of each of H2S⋯ CuI , H2S⋯ AgI and three isotopologues of H2S⋯ AuI have been measured by chirped-pulse Fourier transform microwave spectroscopy. The spectra are interpreted to determine geometries for the complexes and to establish the values of structural parameters. The complexes have Cs symmetry at equilibrium and have a pyramidal configuration about the sulfur atom. The local C2 axis of the hydrogen sulfide molecule intersects the linear axis defined by the three heavy atoms at an angle, ϕ = 75.00(47)° for M = Cu, ϕ = 78.43(76)° for M = Ag, and ϕ = 71.587(13)° for M = Au. The trend in the molecular geometries is consistent with significant relativistic effects in the gold-containing complex. The force constant describing the interaction between the H2S and MI sub-units is determined from the measured centrifugal distortion constant, ΔJ, of each complex. Nuclear quadrupole coupling constants, χa a(M) and χa a(I) (where M denotes the metal atom), are determined for H2S⋯ CuI and H2S⋯ AuI for the first time.

  12. Tuning the Luminescent Properties of a Ag/Au Tetranuclear Complex Featuring Metallophilic Interactions via Solvent-Dependent Structural Isomerization.

    PubMed

    Donamaría, Rocío; Gimeno, M Concepción; Lippolis, Vito; López-de-Luzuriaga, José M; Monge, Miguel; Olmos, M Elena

    2016-11-07

    In this paper the reaction products of the basic gold(I) species [Au(C6Cl5)2](-) against the acid salt Ag(OClO3) in the presence of the S-donor macrocyclic ligand 1,4,7-trithiacyclononane ([9]aneS3) are studied in different solvents. Two different isomers of stoichiometry [{Au(C6Cl5)2}Ag([9]aneS3)]2 were isolated depending on the solvent used, dichloromethane or tetrahydrofuran, which show different luminescence in the solid state. X-ray diffraction studies of these compounds reveals that both show the same heteropolynuclear Ag···Au···Au···Ag system but with different Au···Au interaction distances and different relative positions of the cationic fragment [Ag([9]aneS3)](+) in the structure with respect the bimetallic Au···Au core. This work includes a study of the optical properties of both isomers, as well as time-dependent density functional theory calculations that were performed to determine the origin of their different luminescence.

  13. Using Narrative Intervention to Accelerate Canonical Story Grammar and Complex Language Growth in Culturally Diverse Preschoolers

    ERIC Educational Resources Information Center

    Petersen, Douglas B.; Spencer, Trina D.

    2016-01-01

    Oral narratives are a commonly used, meaningful means of communication that reflects academic language. New state curriculum standards include narrative-related language expectations for young school-age children, including story grammar and complex language. This article provides a review of preschool narrative-based language intervention…

  14. Ag Nanoparticles-enhanced Fluorescence of Terbium-Deferasirox Complexes for the Highly Sensitive Determination of Deferasirox.

    PubMed

    Abolhasani, Jafar; Naderali, Roza; Hassanzadeh, Javad

    2016-01-01

    We describe the effect of different sized gold and silver nanoparticles on the terbium sensitized fluorescence of deferasirox. It is indicated that silver nanostructures, especially 18 nm Ag nanoparticles (AgNPs), have a remarkable amplifying effect compared to Au nanoparticles. Based on this observation, a highly sensitive and selective method was developed for the determination of deferasirox. Effects of various parameters like AgNPs and Tb(3+) concentration and pH of media were investigated. Under the optimal conditions, a calibration curve was plotted as the fluorescence intensities versus the concentration of deferasirox in the range of 0.1 to 200 nmol L(-1), and detection limit of 0.03 nmol L(-1) was obtained. The method has good linearity, recovery, reproducibility and sensitivity, and was satisfactorily applied for the determination of deferasirox in urine and pharmaceutical samples.

  15. Finite difference method accelerated with sparse solvers for structural analysis of the metal-organic complexes

    NASA Astrophysics Data System (ADS)

    Guda, A. A.; Guda, S. A.; Soldatov, M. A.; Lomachenko, K. A.; Bugaev, A. L.; Lamberti, C.; Gawelda, W.; Bressler, C.; Smolentsev, G.; Soldatov, A. V.; Joly, Y.

    2016-05-01

    Finite difference method (FDM) implemented in the FDMNES software [Phys. Rev. B, 2001, 63, 125120] was revised. Thorough analysis shows, that the calculated diagonal in the FDM matrix consists of about 96% zero elements. Thus a sparse solver would be more suitable for the problem instead of traditional Gaussian elimination for the diagonal neighbourhood. We have tried several iterative sparse solvers and the direct one MUMPS solver with METIS ordering turned out to be the best. Compared to the Gaussian solver present method is up to 40 times faster and allows XANES simulations for complex systems already on personal computers. We show applicability of the software for metal-organic [Fe(bpy)3]2+ complex both for low spin and high spin states populated after laser excitation.

  16. Dinuclear vs. mononuclear complexes: accelerated, metal-dependent ring-opening polymerization of lactide.

    PubMed

    Normand, M; Roisnel, T; Carpentier, J-F; Kirillov, E

    2013-12-25

    Dinuclear complexes of aluminum and indium with a bis(phenoxy-imine) platform have been synthesized and used in the polymerization of lactide. Kinetic studies demonstrate that the dialuminum precursor provides a more favorable reaction pathway in terms of activation free energy than that of directly related monoaluminum systems. No similar trend is observed with the corresponding diindium-monoindium systems, which is attributed to a dissimilar ROP mechanism.

  17. HDF5-FastQuery: Accelerating Complex Queries on HDF Datasets usingFast Bitmap Indices

    SciTech Connect

    Gosink, Luke; Shalf, John; Stockinger, Kurt; Wu, Kesheng; Bethel,Wes

    2006-03-30

    Large scale scientific data is often stored in scientific data formats such as FITS, netCDF and HDF. These storage formats are of particular interest to the scientific user community since they provide multi-dimensional storage and retrieval. However, one of the drawbacks of these storage formats is that they do not support semantic indexing which is important for interactive data analysis where scientists look for features of interests such as ''Find all supernova explosions where energy > 10{sup 5} and temperature > 10{sup 6}''. In this paper we present a novel approach called HDF5-FastQuery to accelerate the data access of large HDF5 files by introducing multi-dimensional semantic indexing. Our implementation leverages an efficient indexing technology called bitmap indexing that has been widely used in the database community. Bitmap indices are especially well suited for interactive exploration of large-scale read only data. Storing the bitmap indices into the HDF5 file has the following advantages: (a) Significant performance speedup of accessing subsets of multi-dimensional data and (b) portability of the indices across multiple computer platforms. We will present an API that simplifies the execution of queries on HDF5 files for general scientific applications and data analysis. The design is flexible enough to accommodate the use of arbitrary indexing technology for semantic range queries. We will also provide a detailed performance analysis of HDF5-FastQuery for both synthetic and scientific data. The results demonstrate that our proposed approach for multi-dimensional queries is up to a factor of 2 faster than HDF5.

  18. Polynuclear Gold [AuI]4, [AuI]8, and Bimetallic [AuI 4AgI] Complexes: C−H Functionalization of Carbonyl Compounds and Homogeneous Carbonylation of Amines

    PubMed Central

    Smirnova, Ekaterina S.; Muñoz Molina, José M.; Johnson, Alice; Bandeira, Nuno A. G.; Bo, Carles

    2016-01-01

    Abstract The synthesis of tetranuclear gold complexes, a structurally unprecedented octanuclear complex with a planar [AuI 8] core, and pentanuclear [AuI 4MI] (M=Cu, Ag) complexes is presented. The linear [AuI 4] complex undergoes C−H functionalization of carbonyl compounds under mild reaction conditions. In addition, [AuI 4AgI] catalyzes the carbonylation of primary amines to form ureas under homogeneous conditions with efficiencies higher than those achieved by gold nanoparticles. PMID:27167611

  19. Development of a cryogenic load frame for the neutron diffractometer at Takumi in Japan Proton Accelerator Research Complex.

    PubMed

    Jin, Xinzhe; Nakamoto, Tatsushi; Harjo, Stefanus; Hemmi, Tsutomu; Umeno, Takahiro; Ogitsu, Toru; Yamamoto, Akira; Sugano, Michinaka; Aizawa, Kazuya; Abe, Jun; Gong, Wu; Iwahashi, Takaaki

    2013-06-01

    To prepare for projects such as the Large Hadron Collider upgrade, International Thermonuclear Experimental Reactor and Demonstration reactor, it is important to form a clear understanding of stress-strain properties of the materials that make up superconducting magnets. Thus, we have been studying the mechanical properties of superconducting wires using neutron diffraction measurements. To simulate operational conditions such as temperature, stress, and strain, we developed a cryogenic load frame for stress-strain measurements of materials using a neutron diffractometer at Japan Proton Accelerator Research Complex (J-PARC) Takumi beam line. The maximum load that can be applied to a sample using an external driving machine is 50 kN. Using a Gifford-MacMahon cryocooler, samples can be measured down to temperatures below 10 K when loaded. In the present paper, we describe the details of the cryogenic load frame with its test results by using type-304 stainless steel wire.

  20. 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.

  1. Different structural preference of Ag(I) and Au(I) in neutral and cationic luminescent heteropolynuclear platinum(II) complexes: Z (U)-shaped Pt2M2 type vs. trinuclear PtM2 type.

    PubMed

    Nishihara, Kazuki; Ueda, Misa; Higashitani, Ami; Nakao, Yoshihide; Arikawa, Yasuhiro; Horiuchi, Shinnosuke; Sakuda, Eri; Umakoshi, Keisuke

    2016-03-28

    The reactions of monocationic Pt(II) complexes bearing N^C chelate ligands and Me2pzH, [Pt(N^C)(Me2pzH)2]PF6 (N^C = 2-phenylpyridinate (ppy(-)), 2-(2,4-difluorophenyl)pyridinate (dfppy(-)), benzo[h]quinolinate (bzq(-)); Me2pzH = 3,5-dimethylpyrazole), with Ag(I) ions gave Z (or U)-shaped neutral tetranuclear Pt2Ag2 complexes [Pt2Ag2(N^C)2(Me2pz)4], while those with Au(I) ions gave neutral trinuclear PtAu2 complexes [PtAu2(N^C)(Me2pz)3]. On the contrary, the reactions of the dicationic Pt(II) complex bearing a N^N chelate ligand and Me2pzH, [Pt(bpy)(Me2pzH)2](PF6)2 (bpy = 2,2'-bipyridine), with Ag(I) and Au(I) ions both gave Z (or U)-shaped dicationic tetranuclear Pt2M2 complexes, [Pt2M2(bpy)2(Me2pz)4](PF6)2 (M = Ag, Au). The structures of heteropolynuclear Pt(II) complexes were dominated by the nature of incorporated group 11 metal ions and the charge of complexes.

  2. A novel chemiluminescence quenching method for determination of sulfonamides in pharmaceutical and biological fluid based on luminol-Ag(III) complex reaction in alkaline solution.

    PubMed

    Sun, Hanwen; Chen, Peiyun; Li, Liqing; Cheng, Peng

    2011-05-01

    A novel chemiluminescence (CL) quenching method for the determination of sulfonamides is proposed. The CL reaction between Ag(III) complex [Ag(HIO₆)₂]⁵⁻ and luminol in alkaline solution was investigated. The quenching effect of sulfonamides on CL emission of [Ag(HIO₆)₂]⁵⁻-luminol system was found. Quenching degree of CL emission was proportional to sulfonamide concentration. The effects of the reaction conditions on CL emission and quenching were examined. Under optimal conditions, the detection limits (s/n = 3) were 7.2, 17 and 8.3 ng/mL for sulfadiazine, sulfameter, and sulfadimethoxine, respectively. The recoveries of the three drugs were in the range of 91.3-110% with RSDs of 1.9-2.7% for urine samples, and 106-112% with RSDs of 1.6-2.8% for serum samples. The proposed method was used for the determination of sulfadiazine at clinically relevant concentrations in real urine and serum samples with satisfactory results.

  3. GPU technology as a platform for accelerating local complexity analysis of protein sequences.

    PubMed

    Papadopoulos, Agathoklis; Kirmitzoglou, Ioannis; Promponas, Vasilis J; Theocharides, Theocharis

    2013-01-01

    The use of GPGPU programming paradigm (running CUDA-enabled algorithms on GPU cards) in Bioinformatics showed promising results [1]. As such a similar approach can be used to speedup other algorithms such as CAST, a popular tool used for masking low-complexity regions (LCRs) in protein sequences [2] with increased sensitivity. We developed and implemented a CUDA-enabled version (GPU_CAST) of the multi-threaded version of CAST software first presented in [3] and optimized in [4]. The proposed software implementation uses the nVIDIA CUDA libraries and the GPGPU programming paradigm to take advantage of the inherent parallel characteristics of the CAST algorithm to execute the calculations on the GPU card of the host computer system. The GPU-based implementation presented in this work, is compared against the multi-threaded, multi-core optimized version of CAST [4] and yielded speedups of 5x-10x for large protein sequence datasets.

  4. Synthesis and linkage isomerization of thiolato-bridged Ru(II)Ag(I)Ru(II) trinuclear complex with D-penicillaminate.

    PubMed

    Tamura, Motoshi; Yamagishi, Masakazu; Kawamoto, Tatsuya; Igashira-Kamiyama, Asako; Tsuge, Kiyoshi; Konno, Takumi

    2009-09-21

    The reaction of [Ru(solvent)(2)(bpy)(2)](2+) (bpy = 2,2'-bipyridine) with D-H(2)pen (D-penicillamine) in ethanol/water in the presence of Ag(+) gave a thiolato-bridged Ru(II)Ag(I)Ru(II) trinuclear complex, [Ag{Ru(D-Hpen)(bpy)(2)}(2)](3+) ([1](3+)), in which two octahedral [Ru(II)(D-Hpen)(bpy)(2)](+) units are linked by a linear Ag(I) ion. Of three possible isomers (Delta(D)Delta(D), Delta(D)Lambda(D), and Lambda(D)Lambda(D)), [1](3+) formed the Delta(D)Delta(D) and Lambda(D)Lambda(D) isomers that were separately isolated by fractional crystallization with the use of [Sb(2)(R,R-tartrato)(2)](2-). In [1](3+), each D-Hpen ligand chelates to a Ru(II) center through thiolate and carboxylate groups, while an amine group of D-Hpen is protonated and does not participate in the coordination. On refluxing in ethanol/water, the Delta(D)Delta(D) isomer of [1](3+) was converted to Delta(D)Delta(D)-[2](3+), in which each D-Hpen ligand chelates to a Ru(II) center through thiolate and amine groups with a non-coordinating carboxyl group. On the other hand, a similar thermal linkage isomerization was not noticed for the Lambda(D)Lambda(D) isomer of [1](3+) under the same conditions. The isolated Delta(D)Delta(D)-[1](3+), Lambda(D)Lambda(D)-[1](3+), and Delta(D)Delta(D)-[2](3+) were fully characterized by electronic absorption, CD, and NMR spectroscopies, along with single-crystal X-ray crystallography for Lambda(D)Lambda(D)-[1](3+) and Delta(D)Delta(D)-[2](3+).

  5. Shedding Light on the Photochemistry of Coinage-Metal Phosphorescent Materials: A Time-Resolved Laue Diffraction Study of an AgI-CuI Tetranuclear Complex

    SciTech Connect

    Jarzembska, Katarzyna N.; Kami,; #324; ski, Radoslaw; Fournier, Bertrand; Trzop, El; #380; bieta,; Sokolow, Jesse D.; Henning, Robert; Chen, Yang; Coppens, Philip

    2014-11-14

    The triplet excited state of a new crystalline form of a tetranuclear coordination d10–d10-type complex, Ag2Cu2L4 (L = 2-diphenylphosphino-3-methylindole ligand), containing AgI and CuI metal centers has been explored using the Laue pump–probe technique with ≈80 ps time resolution. The relatively short lifetime of 1 μs is accompanied by significant photoinduced structural changes, as large as the Ag1···Cu2 distance shortening by 0.59(3) Å. The results show a pronounced strengthening of the argentophilic interactions and formation of new Ag···Cu bonds on excitation. Theoretical calculations indicate that the structural changes are due to a ligand-to-metal charge transfer (LMCT) strengthening the Ag···Ag interaction, mainly occurring from the methylindole ligands to the silver metal centers. QM/MM optimizations of the ground and excited states of the complex support the experimental results. Comparison with isolated molecule optimizations demonstrates the restricting effect of the crystalline matrix on photoinduced distortions. The work represents the first time-resolved Laue diffraction study of a heteronuclear coordination complex and provides new information on the nature of photoresponse of coinage metal complexes, which have been the subject of extensive studies.

  6. An efficient algorithm to accelerate the discovery of complex material formulations

    NASA Astrophysics Data System (ADS)

    Brell, George; Li, Genyuan; Rabitz, Herschel

    2010-05-01

    The identification of complex multicomponent material formulations that possess specific optimal properties is a challenging task in materials discovery. The high dimensional composition space needs to be adequately sampled and the properties measured with the goal of efficiently identifying effective formulations. This task must also take into account mass fraction and possibly other constraints placed on the material components. Either combinatorial or noncombinatorial sampling of the composition space may be employed in practice. This paper introduces random sampling-high dimensional model representation (RS-HDMR) as an algorithmic tool to facilitate these nonlinear multivariate problems. RS-HDMR serves as a means to accurately interpolate over sampled materials, and simulations of the technique show that it can be very efficient. A variety of simulations is carried out modeling multicomponent→property relationships, and the results show that the number of sampled materials to attain a given level of accuracy for a predicted property does not significantly depend on the number of components in the formulation. Although RS-HDMR best operates in the laboratory by guided iterative rounds of random sampling of the composition space along with property observation, the technique was tested successfully on two existing databases of a seven component phosphor material and a four component deNOx catalyst for reduction of NO with C3H6.

  7. Accelerated fluctuation analysis by graphic cards and complex pattern formation in financial markets

    NASA Astrophysics Data System (ADS)

    Preis, Tobias; Virnau, Peter; Paul, Wolfgang; Schneider, Johannes J.

    2009-09-01

    The compute unified device architecture is an almost conventional programming approach for managing computations on a graphics processing unit (GPU) as a data-parallel computing device. With a maximum number of 240 cores in combination with a high memory bandwidth, a recent GPU offers resources for computational physics. We apply this technology to methods of fluctuation analysis, which includes determination of the scaling behavior of a stochastic process and the equilibrium autocorrelation function. Additionally, the recently introduced pattern formation conformity (Preis T et al 2008 Europhys. Lett. 82 68005), which quantifies pattern-based complex short-time correlations of a time series, is calculated on a GPU and analyzed in detail. Results are obtained up to 84 times faster than on a current central processing unit core. When we apply this method to high-frequency time series of the German BUND future, we find significant pattern-based correlations on short time scales. Furthermore, an anti-persistent behavior can be found on short time scales. Additionally, we compare the recent GPU generation, which provides a theoretical peak performance of up to roughly 1012 floating point operations per second with the previous one. .

  8. A Tensor-Train accelerated solver for integral equations in complex geometries

    NASA Astrophysics Data System (ADS)

    Corona, Eduardo; Rahimian, Abtin; Zorin, Denis

    2017-04-01

    We present a framework using the Quantized Tensor Train (QTT) decomposition to accurately and efficiently solve volume and boundary integral equations in three dimensions. We describe how the QTT decomposition can be used as a hierarchical compression and inversion scheme for matrices arising from the discretization of integral equations. For a broad range of problems, computational and storage costs of the inversion scheme are extremely modest O (log ⁡ N) and once the inverse is computed, it can be applied in O (Nlog ⁡ N) . We analyze the QTT ranks for hierarchically low rank matrices and discuss its relationship to commonly used hierarchical compression techniques such as FMM and HSS. We prove that the QTT ranks are bounded for translation-invariant systems and argue that this behavior extends to non-translation invariant volume and boundary integrals. For volume integrals, the QTT decomposition provides an efficient direct solver requiring significantly less memory compared to other fast direct solvers. We present results demonstrating the remarkable performance of the QTT-based solver when applied to both translation and non-translation invariant volume integrals in 3D. For boundary integral equations, we demonstrate that using a QTT decomposition to construct preconditioners for a Krylov subspace method leads to an efficient and robust solver with a small memory footprint. We test the QTT preconditioners in the iterative solution of an exterior elliptic boundary value problem (Laplace) formulated as a boundary integral equation in complex, multiply connected geometries.

  9. Structural insights into how Yrb2p accelerates the assembly of the Xpo1p nuclear export complex.

    PubMed

    Koyama, Masako; Shirai, Natsuki; Matsuura, Yoshiyuki

    2014-11-06

    Proteins and ribonucleoproteins containing a nuclear export signal (NES) assemble with the exportin Xpo1p (yeast CRM1) and Gsp1p-GTP (yeast Ran-GTP) in the nucleus and exit through the nuclear pore complex. In the cytoplasm, Yrb1p (yeast RanBP1) displaces NES from Xpo1p. Efficient export of NES-cargoes requires Yrb2p (yeast RanBP3), a primarily nuclear protein containing nucleoporin-like phenylalanine-glycine (FG) repeats and a low-affinity Gsp1p-binding domain (RanBD). Here, we show that Yrb2p strikingly accelerates the association of Gsp1p-GTP and NES to Xpo1p. We have solved the crystal structure of the Xpo1p-Yrb2p-Gsp1p-GTP complex, a key assembly intermediate that can bind cargo rapidly. Although the NES-binding cleft of Xpo1p is closed in this intermediate, our data suggest that preloading of Gsp1p-GTP onto Xpo1p by Yrb2p, conformational flexibility of Xpo1p, and the low affinity of RanBD enable active displacement of Yrb2p RanBD by NES to occur effectively. The structure also reveals the major binding sites for FG repeats on Xpo1p.

  10. Crystal structure of an ethylene sorption complex of fully vacuum-dehydrated fully Ag+-exchanged zeolite X (FAU). Silver atoms have reduced ethylene to give CH2 2- carbanions at framework oxide vacancies.

    PubMed

    Lee, Young Mi; Choi, Seo Jung; Kim, Yang; Seff, Karl

    2005-11-03

    The crystal structure of an ethylene sorption complex of fully vacuum-dehydrated fully Ag(+)-exchanged zeolite X (FAU), a = 24.865(2) A, has been determined by single-crystal X-ray diffraction techniques in the cubic space group Fd at 21 degrees C. It is very different from the ethylene complex of Ag(92)-X that had been dehydrated at 400 degrees C in flowing oxygen, as were the two dehydrated structures. The crystal was prepared by ion exchange in a flowing stream of aqueous 0.05 M AgNO(3) for 3 days, followed by dehydration at 400 degrees C and 2 x 10(-6) Torr for 2 days, followed by exposure to 300 Torr of zeolitically dry ethylene gas for 2 h at 21 degrees C. The structure was determined in this atmosphere and was refined using all data to the final error indices (based upon the 534 reflections for which F(o) > 4sigma(F(o))) R(1) = 0.062 and wR(2) = 0.135. In this structure, per unit cell, 14 Ag(+) ions were found at the octahedral site I (Ag-O = 2.611(9) A), and 32 partially reduced Ag(+) ions fill two different site I' positions deep in the sodalite cavities (Ag-O = 2.601(13) and 2.618(12) A). The sodalite cavities host two different cationic silver clusters. In about 47% of sodalite units, eight silver atoms form interpenetrating tetrahedra, Ag(8)(n+) (n = 4 is suggested), with T(d)() symmetry. The other 53% of the sodalite units host cyclo-Ag(4)(m+) (m = 2 is suggested) cations with near S(4) symmetry. These clusters are very similar to those in vacuum-dehydrated Ag(92)-X. Thirty-two Ag(+) ions fill the single 6-rings, 15 at site II' (Ag-O = 2.492(10) A), and 17 at site II (Ag-O = 2.460(9) A). The latter 17 lie in supercages where each forms a lateral pi-complex with an ethylene molecule. In turn, each C(2)H(4) molecule forms two cis electrostatic hydrogen bonds to framework oxygens. The remaining 14 Ag+ ions occupy three different II' sites. Vacuum dehydration had caused substantial decomposition: per unit cell, 30 of the 92 Ag(+) ions were reduced and 15

  11. Surrogate accelerated sampling of reservoir models with complex structures using sparse polynomial chaos expansion

    NASA Astrophysics Data System (ADS)

    Bazargan, Hamid; Christie, Mike; Elsheikh, Ahmed H.; Ahmadi, Mohammad

    2015-12-01

    Markov Chain Monte Carlo (MCMC) methods are often used to probe the posterior probability distribution in inverse problems. This allows for computation of estimates of uncertain system responses conditioned on given observational data by means of approximate integration. However, MCMC methods suffer from the computational complexities in the case of expensive models as in the case of subsurface flow models. Hence, it is of great interest to develop alterative efficient methods utilizing emulators, that are cheap to evaluate, in order to replace the full physics simulator. In the current work, we develop a technique based on sparse response surfaces to represent the flow response within a subsurface reservoir and thus enable efficient exploration of the posterior probability density function and the conditional expectations given the data. Polynomial Chaos Expansion (PCE) is a powerful tool to quantify uncertainty in dynamical systems when there is probabilistic uncertainty in the system parameters. In the context of subsurface flow model, it has been shown to be more accurate and efficient compared with traditional experimental design (ED). PCEs have a significant advantage over other response surfaces as the convergence to the true probability distribution when the order of the PCE is increased can be proved for the random variables with finite variances. However, the major drawback of PCE is related to the curse of dimensionality as the number of terms to be estimated grows drastically with the number of the input random variables. This renders the computational cost of classical PCE schemes unaffordable for reservoir simulation purposes when the deterministic finite element model is expensive to evaluate. To address this issue, we propose the reduced-terms polynomial chaos representation which uses an impact factor to only retain the most relevant terms of the PCE decomposition. Accordingly, the reduced-terms polynomial chaos proxy can be used as the pseudo

  12. Assessment and acceleration of binding energy calculations for protein-ligand complexes by the fragment molecular orbital method.

    PubMed

    Otsuka, Takao; Okimoto, Noriaki; Taiji, Makoto

    2015-11-15

    In the field of drug discovery, it is important to accurately predict the binding affinities between target proteins and drug applicant molecules. Many of the computational methods available for evaluating binding affinities have adopted molecular mechanics-based force fields, although they cannot fully describe protein-ligand interactions. A noteworthy computational method in development involves large-scale electronic structure calculations. Fragment molecular orbital (FMO) method, which is one of such large-scale calculation techniques, is applied in this study for calculating the binding energies between proteins and ligands. By testing the effects of specific FMO calculation conditions (including fragmentation size, basis sets, electron correlation, exchange-correlation functionals, and solvation effects) on the binding energies of the FK506-binding protein and 10 ligand complex molecule, we have found that the standard FMO calculation condition, FMO2-MP2/6-31G(d), is suitable for evaluating the protein-ligand interactions. The correlation coefficient between the binding energies calculated with this FMO calculation condition and experimental values is determined to be R = 0.77. Based on these results, we also propose a practical scheme for predicting binding affinities by combining the FMO method with the quantitative structure-activity relationship (QSAR) model. The results of this combined method can be directly compared with experimental binding affinities. The FMO and QSAR combined scheme shows a higher correlation with experimental data (R = 0.91). Furthermore, we propose an acceleration scheme for the binding energy calculations using a multilayer FMO method focusing on the protein-ligand interaction distance. Our acceleration scheme, which uses FMO2-HF/STO-3G:MP2/6-31G(d) at R(int) = 7.0 Å, reduces computational costs, while maintaining accuracy in the evaluation of binding energy.

  13. BaFe12O19-chitosan Schiff-base Ag (I) complexes embedded in carbon nanotube networks for high-performance electromagnetic materials

    PubMed Central

    Zhao, Jie; Xie, Yu; Guan, Dongsheng; Hua, Helin; Zhong, Rong; Qin, Yuancheng; Fang, Jing; Liu, Huilong; Chen, Junhong

    2015-01-01

    The multiwalled carbon nanotubes/BaFe12O19-chitosan (MCNTs/BF-CS) Schiff base Ag (I) complex composites were synthesized successfully by a chemical bonding method. The morphology and structures of the composites were characterized with electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. Their conductive properties were measured using a four-probe conductivity tester at room temperature, and their magnetic properties were tested by a vibrating sample magnetometer. The results show that the BF-CS Schiff base Ag (I) complexes are embedded into MCNT networks. When the mass ratio of MCNTs and BF-CS Schiff base is 0.95:1, the conductivity, Ms (saturation magnetization), Mr (residual magnetization), and Hc (coercivity) of the BF-CS Schiff base composites reach 1.908 S cm−1, 28.20 emu g−1, 16.66 emu g−1 and 3604.79 Oe, respectively. Finally, a possible magnetic mechanism of the composites has also been proposed. PMID:26218269

  14. Energies and excited-state dynamics of 1Bu+, 1Bu- and 3Ag- states of carotenoids bound to LH2 antenna complexes from purple photosynthetic bacteria

    NASA Astrophysics Data System (ADS)

    Christiana, Rebecca; Miki, Takeshi; Kakitani, Yoshinori; Aoyagi, Shiho; Koyama, Yasushi; Limantara, Leenawaty

    2009-10-01

    Time-resolved pump-probe stimulated-emission and transient-absorption spectra were recorded after excitation with ˜30 fs pulses to the 1Bu+(0) and optically-forbidden diabatic levels of carotenoids, neurosporene, spheroidene and lycopene having n = 9-11 double bonds, bound to LH2 antenna complexes from Rhodobacter sphaeroides G1C, 2.4.1 and Rhodospirillum molischianum. The low-energy shift of stimulated emission from the covalent 1Bu-(0) and 3Ag-(0) levels slightly larger than that from the ionic 1Bu+(0) state suggests the polarization, whereas more efficient triplet generation suggests the twisting of the conjugated chain in Cars bound to the LH2 complexes, when compared to Cars free in solution.

  15. Bonding analyses, formation energies, and vibrational properties of M-R2dtc complexes (M=Ag(I), Ni(II), Cu(II), or Zn(II)).

    PubMed

    Georgieva, I; Trendafilova, N

    2007-12-20

    Detailed theoretical studies based on density functional theory (DFT)/B3LYP calculations of dimethyl- and diethyldithiocarbamate complexes of Ni(II), Cu(II), Zn(II), and Ag(I) are performed to characterize the metal-ligand bonding type as well as the metal-ligand bonding strength depending on the metal and the dialkyl substituent. The metal-ligand interactions in the studied complexes are investigated by means of charge decomposition analysis, energy partitioning analysis (EPA), and natural bond orbital analysis. According to the EPA calculations, the electrostatic attraction is the dominant contribution to the M-S2(R2dtc) (dtc=dithiocarbamate) bonding. The electrostatic and the orbital energies follow the order of the total binding energy, and hence both contributions are responsible for the binding energy order of M(R2dtc)2 complexes. The stability of the M(R2dtc)2 complexes is estimated by means of calculated formation reaction energies in the gas phase and solution, and it decreases in the order Ni(R2dtc)2>Cu(R2dtc)2>Zn(R2dtc)2. Larger formation reaction energies are found for M(Et2dtc)2 than for M(Me2dtc)2 complexes. The calculations predict stabilization of M(II)(R2dtc)2 complexes going from the gas phase to a polar solvent and destabilization of the bidentate AgR2dtc complex in a polar solvent. Gas-phase frequency calculations of all possible bonding types, symmetrical, asymmetrical, and uni- and bidentate, predict one band due to the nu(CS) IR absorption, and therefore the number of the bands in the 1060-920 cm(-1) region could not be used to discern the metal-ligand bonding type. Periodic DFT frequency calculations for Cu(Et2dtc)2 reveal that the splitting observed in the solid-state spectra of the complexes arises from the nonplanar MS4 fragment and intermolecular contacts but not from asymmetrical bonding. The calculations suggest that the important vibrational characteristic that can be used to discern uni- and bidentate bonding is the Raman activity of

  16. Metal Ion Binding: An Electronic Structure Study of M+(dimethyl ether)(n), M= Cu, Ag and Au, (n= 1 - 4) Complexes

    SciTech Connect

    Feller, David F. ); Dixon, David A. )

    2002-01-01

    The structures and incremental binding enthalpies of cation-ligand complexes formed from a single coinage metal cation (Cu+, Ag+ and Au+) and as many as four dimethyl ether (DME) ligands are studied with second order perturbation theory (MP2) and coupled cluster theory (CCSD(T)). Basis sets of up to augmented quintuple zeta quality were used in an effort to minimize basis set truncation error. The present results are compared with recent collision-induced dissociation measurements for the Cu+(DME)n complexes, as well as with related complexes in which water either replaces dimethyl ether as the ligand or alkali metal cations replace the coinage metals. Agreement between the theoretical and experimental incremental binding enthalpies (kcal/mol) is good for the two larger copper complexes: DH0(Cu+(DME)3)= 13.9 (theory) vs 13.1? 0.9 kcal/mol (expt.) and DH0(Cu+(DME)4)=11.5 (theory) vs 10.8? 2.3 (expt.). For the two smaller, more tightly bound copper complexes, the level of agreement i s somewhat poorer: DH0(Cu+(DME))= 48.4 (theory) vs 44.3? 2.7 kcal/mol (expt.) and DH0(Cu+(DME)2)= 51.3 (theory) vs 46.1? 1.8 (expt.). In general, DME binds copper, silver and gold 15% - 25% more strongly than water.

  17. 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.

  18. 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.

  19. Investigation of induced radioactivity in the Linac-Adone accelerator complex for the management of the decommissioned material.

    PubMed

    Mora, Juan Carlos; Bedogni, Roberto; Esposito, Adolfo; Cancio, David

    2007-03-01

    The LINAC-ADONE accelerator complex of the INFN-LNF Frascati National Laboratories, operating for 27 y prior to the commissioning of DAPhiNE, was dismantled in 1993. The scraps resulting from the decommissioning of LINAC-ADPhiNE have been temporarily stored in the same Frascati laboratory, waiting for definitive disposal. Relying on recommendations of the IAEA, European Commission and Italian committees, an experimental characterization study of the LNF repository was performed. The main objective was a classification of the scraps on the basis of internationally recognized "clearance levels," which are 0.1 Bq g(-1) for the isotopes of interest for this work. Secondly, a measurement of the materials suspected to be above 0.1 Bq g(-1) was planned. Activation isotopes were expected from the aluminum, copper, steel, and iron of the LINAC and the ADONE ring sections. For screening purposes, the repository area has been divided into zones, where in-situ measurements with a portable HP-Ge detector have been performed. In addition, small samples have been cut from a representative number of pieces, and accurate laboratory measurements have been made with a low background HP-Ge spectrometer. The experimental results are in good agreement with other studies and show that a large part of the material is below the mentioned specific activity level.

  20. Electronic packing frustration in complex intermetallic structures: the role of chemical pressure in Ca2Ag7.

    PubMed

    Fredrickson, Daniel C

    2011-07-06

    The assignment of distinct roles to electronics and sterics has a long history in our rationalization of chemical phenomena. Exploratory synthesis in the field of intermetallic compounds challenges this dichotomy with a growing list of phases whose structural chemistry points to an interplay between atomic size effects and orbital interactions. In this paper, we begin with a simple model for how this interdependence may arise in the dense atomic packing of intermetallics: correlations between interatomic distances lead to the inability of a phase to optimize bonds without simultaneously shortening electronically under-supported contacts, a conflict we term electronic packing frustration (EPF). An anticipated consequence of this frustration is the emergence of chemical pressures (CPs) acting on the affected atoms. We develop a theoretical method based on DFT-calibrated μ(2)-Hückel calculations for probing these CP effects. Applying this method to the Ca(2)Ag(7) structure, a variant of the CaCu(5) type with defect planes, reveals its formation is EPF-driven. The defect planes resolve severe CPs surrounding the Ca atoms in a hypothetical CaCu(5)-type CaAg(5) phase. CP analysis also points to a rationale for these results in terms of a CP analogue of the pressure-distance paradox and predicts that the impetus for defect plane insertion is tunable via variations in the electron count.

  1. Geology, alteration and mesothermal Au-Ag-mineralization associated with a volcanic-intrusive complex at Mt. Shamrock-Mt. Ophir, SE Queensland

    NASA Astrophysics Data System (ADS)

    Williams, P. J.

    1991-04-01

    Au-Ag mineralization in the Mt-Shamrock — Mt. Ophir area of SE Queensland is related to a geographically-isolated calc-alkaline igneous centre consisting of high level plutonic and minor intrusions emplaced into the eroded remains of a silicic volcanic ediface and its basement. Mineralization occurs in both the igneous rocks and in the Permian siltstone country rocks and is controlled by a NE-trending structure parallel to Late Triassic lineaments. This structure is unrelated to, and younger than the exposed intrusions. Au-Ag-As-rich, Cu-Mo-poor mineralization occurs in breccias and veinlet networks within pervasively altered rocks characterized by silicification and H (sericite), CO2 (calcite-ankerite), Na (albite), B (tourmaline), and S (pyrite) metasomatism. Secondary mineral compositions suggest that most of this alteration occurred at temperatures between 350 ° and 400 °C. The alteration was complex in detail and characterized by multiple hydrothermal events and space and/or time variations of physico-chemical conditions. Although some of these features are similar to prophyry deposits the chemical character of the alteration and mineralization is not typical of Cu-Mo-Au porphyries and has more in common with tectonometamorphic Au deposits formed at considerably greater depths.

  2. Complex Stoichiometry-Dependent Reordering of 3,4,9,10-Perylenetetracarboxylic Dianhydride on Ag(111) upon K Intercalation

    PubMed Central

    2015-01-01

    Alkali metal atoms are frequently used for simple yet efficient n-type doping of organic semiconductors and as an ingredient of the recently discovered polycyclic aromatic hydrocarbon superconductors. However, the incorporation of dopants from the gas phase into molecular crystal structures needs to be controlled and well understood in order to optimize the electronic properties (charge carrier density and mobility) of the target material. Here, we report that potassium intercalation into the pristine 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) monolayer domains on a Ag(111) substrate induces distinct stoichiometry-dependent structural reordering processes, resulting in highly ordered and large KxPTCDA domains. The emerging structures are analyzed by low-temperature scanning tunneling microscopy, scanning tunneling hydrogen microscopy (ST[H]M), and low-energy electron diffraction as a function of the stoichiometry. The analysis of the measurements is corroborated by density functional theory calculations. These turn out to be essential for a correct interpretation of the experimental ST[H]M data. The epitaxy types for all intercalated stages are determined as point-on-line. The K atoms adsorb in the vicinity of the oxygen atoms of the PTCDA molecules, and their positions are determined with sub-Ångström precision. This is a crucial prerequisite for the prospective assessment of the electronic properties of such composite films, as they depend rather sensitively on the mutual alignment between donor atoms and acceptor molecules. Our results demonstrate that only the combination of experimental and theoretical approaches allows for an unambiguous explanation of the pronounced reordering of KxPTCDA/Ag(111) upon changing the K content. PMID:26718635

  3. Complex Stoichiometry-Dependent Reordering of 3,4,9,10-Perylenetetracarboxylic Dianhydride on Ag(111) upon K Intercalation.

    PubMed

    Zwick, Christian; Baby, Anu; Gruenewald, Marco; Verwüster, Elisabeth; Hofmann, Oliver T; Forker, Roman; Fratesi, Guido; Brivio, Gian Paolo; Zojer, Egbert; Fritz, Torsten

    2016-02-23

    Alkali metal atoms are frequently used for simple yet efficient n-type doping of organic semiconductors and as an ingredient of the recently discovered polycyclic aromatic hydrocarbon superconductors. However, the incorporation of dopants from the gas phase into molecular crystal structures needs to be controlled and well understood in order to optimize the electronic properties (charge carrier density and mobility) of the target material. Here, we report that potassium intercalation into the pristine 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) monolayer domains on a Ag(111) substrate induces distinct stoichiometry-dependent structural reordering processes, resulting in highly ordered and large KxPTCDA domains. The emerging structures are analyzed by low-temperature scanning tunneling microscopy, scanning tunneling hydrogen microscopy (ST[H]M), and low-energy electron diffraction as a function of the stoichiometry. The analysis of the measurements is corroborated by density functional theory calculations. These turn out to be essential for a correct interpretation of the experimental ST[H]M data. The epitaxy types for all intercalated stages are determined as point-on-line. The K atoms adsorb in the vicinity of the oxygen atoms of the PTCDA molecules, and their positions are determined with sub-Ångström precision. This is a crucial prerequisite for the prospective assessment of the electronic properties of such composite films, as they depend rather sensitively on the mutual alignment between donor atoms and acceptor molecules. Our results demonstrate that only the combination of experimental and theoretical approaches allows for an unambiguous explanation of the pronounced reordering of KxPTCDA/Ag(111) upon changing the K content.

  4. Oligo-nuclear silver thiocyanate complexes with monodentate tertiary phosphine ligands, including novel 'cubane' and 'step' tetramer forms of AgSCN : PR3 (1:1)4.

    PubMed

    Bowmaker, Graham A; Di Nicola, Corrado; Effendy; Hanna, John V; Healy, Peter C; King, Scott P; Marchetti, Fabio; Pettinari, Claudio; Robinson, Ward T; Skelton, Brian W; Sobolev, Alexandre N; Tăbăcaru, Aurel; White, Allan H

    2013-01-07

    Adducts of a number of tertiary pnicogen ligands ER(3) (triphenyl-phosphine and -arsine (PPh(3),AsPh(3)), diphenyl,2-pyridylphosphine (PPh(2)py), tris(4-fluorophenyl)phosphine (P(C(6)H(4)-4F)(3)), tris(2-tolyl)phosphine (P(o-tol)(3)), tris(cyclohexyl)phosphine (PCy(3))), with silver(I) thiocyanate, AgSCN are structurally and spectroscopically characterized. The 1:3 AgSCN : ER(3) complexes structurally defined (for PPh(3),AsPh(3) (diversely solvated)) take the form [(R(3)E)(3)AgX], the thiocyanate X = NCS being N-bound, thus [(Ph(3)E)Ag(NCS)]. A 1:2 complex with PPh(2)py, takes the binuclear form [(pyPh(2)P)(2)Ag()Ag(PPh(2)py)(2)] with an eight-membered cyclic core. 1:1 complexes are defined with PPh(2)py, P(o-tol)(3) and PCy(3); binuclear forms [(R(3)P)Ag()Ag(PR(3))] are obtained with P(o-tol)(3) (two polymorphs), while novel isomeric tetranuclear forms, which may be envisaged as dimers of dimers, are obtained with PPh(2)py, and, as further polymorphs, with PCy(3); these latter may be considered as extensions of the 'cubane' and 'step' forms previously described for [(R(3)E)AgX](4) (X = halide) complexes. Solvent-assisted mechanochemical or solvent-assisted solid-state synthesis methods were employed in some cases, where complexes could not be obtained by conventional solution methods, or where such methods yielded a mixture of polymorphs unsuitable for solid-state spectroscopy. The wavenumbers of the ν(CN) bands in the IR spectra are in broad agreement with the empirical rule that distinguishes bridging from terminal bonding, but exceptions occur for compounds that have a double SCN bridged dimeric structure, and replacement of PPh(3) with PPh(2)py apparently causes a significant decrease in ν(CN) to well below the range expected for bridging SCN in these structures. (31)P CP MAS NMR spectra yield additional parameters that allow a correlation between the structures and spectra.

  5. 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.

  6. Acceleration of polarized protons in circular accelerators

    SciTech Connect

    Courant, E.D.; Ruth, R.D.

    1980-09-12

    The theory of depolarization in circular accelerators is presented. The spin equation is first expressed in terms of the particle orbit and then converted to the equivalent spinor equation. The spinor equation is then solved for three different situations: (1) a beam on a flat top near a resonance, (2) uniform acceleration through an isolated resonance, and (3) a model of a fast resonance jump. Finally, the depolarization coefficient, epsilon, is calculated in terms of properties of the particle orbit and the results are applied to a calculation of depolarization in the AGS.

  7. 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.

  8. Dosimetric characterization of hypofractionated Gamma Knife radiosurgery of large or complex brain tumors versus linear accelerator-based treatments.

    PubMed

    Dong, Peng; Pérez-Andújar, Angélica; Pinnaduwage, Dilini; Braunstein, Steve; Theodosopoulos, Philip; McDermott, Michael; Sneed, Penny; Ma, Lijun

    2016-12-01

    OBJECTIVE Noninvasive Gamma Knife (GK) platforms, such as the relocatable frame and on-board imaging, have enabled hypofractionated GK radiosurgery of large or complex brain lesions. This study aimed to characterize the dosimetric quality of such treatments against linear accelerator-based delivery systems that include the CyberKnife (CK) and volumetric modulated arc therapy (VMAT). METHODS Ten patients treated with VMAT at the authors' institution for large brain tumors (> 3 cm in maximum diameter) were selected for the study. The median prescription dose was 25 Gy (range 20-30 Gy) in 5 fractions. The median planning target volume (PTV) was 9.57 cm(3) (range 1.94-24.81 cm(3)). Treatment planning was performed using Eclipse External Beam Planning V11 for VMAT on the Varian TrueBeam system, Multiplan V4.5 for the CyberKnife VSI System, and Leksell GammaPlan V10.2 for the Gamma Knife Perfexion system. The percentage of the PTV receiving at least the prescription dose was normalized to be identical across all platforms for individual cases. The prescription isodose value for the PTV, conformity index, Paddick gradient index, mean and maximum doses for organs at risk, and normal brain dose at variable isodose volumes ranging from the 5-Gy isodose volume (V5) to the 15-Gy isodose volume (V15) were compared for all of the cases. RESULTS The mean Paddick gradient index was 2.6 ± 0.2, 3.2 ± 0.5, and 4.3 ± 1.0 for GK, CK, and VMAT, respectively (p < 0.002). The mean V15 was 7.5 ± 3.7 cm(3) (range 1.53-13.29 cm(3)), 9.8 ± 5.5 cm(3) (range 2.07-18.45 cm(3)), and 16.1 ± 10.6 cm(3) (range 3.58-36.53 cm(3)) for GK, CK, and VMAT, respectively (p ≤ 0.03, paired 2-tailed t-tests). However, the average conformity index was 1.18, 1.12, and 1.21 for GK, CK, and VMAT, respectively (p > 0.06). The average prescription isodose values were 52% (range 47%-69%), 60% (range 46%-68%), and 88% (range 70%-94%) for GK, CK, and VMAT, respectively, thus producing significant variations in

  9. Siberian Snake solenoid for the AGS

    SciTech Connect

    Ratner, L. G.

    1991-01-01

    Recent experiments at the Indiana University Cyclotron Facility (IUCF) have demonstrated that Siberian Snakes'' can be used to preserve the polarization of an accelerated polarized beam in a circular accelerator. Retrofitting full snakes into accelerators such as the Alternating Gradient Synchrotron (AGS) at Brookhaven is almost impossible due to space limitations, but a partial snake that can correct depolarization due to imperfection resonances with 1/20 to 1/30 of a full strength snake seems to present a viable option. We describe such a device for the AGS and give the design criteria in terms of simplicity of accelerator operation and level of achievable polarization. 2 refs., 5 figs., 1 tab.

  10. The alloying effect and AgCl-directing growth for synthesizing a trimetallic nanoring with improved SERS

    NASA Astrophysics Data System (ADS)

    Han, Shuhua; Zhou, Guangju; Fu, Yunzhi; Ma, Ying; Xu, Li; Zou, Chao; Chen, Wei; Yang, Yun; Huang, Shaoming

    2015-12-01

    We report the synthesis of high quality trimetallic Au/Ag/Pt nanorings (TAAPNs) by using Au/Ag alloy decahedra (AAAD) as templates. The alloying effect and AgCl-directing growth have been investigated in detail during the formation of TAAPN. It was found that the doping of Ag in AAAD changes the surrounding environment of Au atoms and decreases the oxidization reduction potential (ORP) of [AuCl2]-/Au because of the alloying effect, resulting in the dissolved O2 molecules that serve as an effective etchant for oxidizing Au to Au(i). Ascorbic acid (AA) and chloroplatinic acid (H2PtCl6) are weak acids which can accelerate the etching by increasing the concentration of H+. The AgCl selectively absorbs on {100} of the decahedra and induces the preferential deposition of H2PtCl6 here via their complexing interaction. AA reduces Pt(iv) and Ag(i) to atoms which grow on {100} facets. The formed Pt/Ag layer changes the etching direction from along [100] to [111] and generates the TAAPN. Besides, it has been noted that the TAAPNs exhibit good Surface Enhanced Raman Scattering (SERS) performance.We report the synthesis of high quality trimetallic Au/Ag/Pt nanorings (TAAPNs) by using Au/Ag alloy decahedra (AAAD) as templates. The alloying effect and AgCl-directing growth have been investigated in detail during the formation of TAAPN. It was found that the doping of Ag in AAAD changes the surrounding environment of Au atoms and decreases the oxidization reduction potential (ORP) of [AuCl2]-/Au because of the alloying effect, resulting in the dissolved O2 molecules that serve as an effective etchant for oxidizing Au to Au(i). Ascorbic acid (AA) and chloroplatinic acid (H2PtCl6) are weak acids which can accelerate the etching by increasing the concentration of H+. The AgCl selectively absorbs on {100} of the decahedra and induces the preferential deposition of H2PtCl6 here via their complexing interaction. AA reduces Pt(iv) and Ag(i) to atoms which grow on {100} facets. The formed

  11. A Comparative Analysis of Reynolds-Averaged Navier-Stokes Model Predictions for Rayleigh-Taylor Instability and Mixing with Constant and Complex Accelerations

    NASA Astrophysics Data System (ADS)

    Schilling, Oleg

    2016-11-01

    Two-, three- and four-equation, single-velocity, multicomponent Reynolds-averaged Navier-Stokes (RANS) models, based on the turbulent kinetic energy dissipation rate or lengthscale, are used to simulate At = 0 . 5 Rayleigh-Taylor turbulent mixing with constant and complex accelerations. The constant acceleration case is inspired by the Cabot and Cook (2006) DNS, and the complex acceleration cases are inspired by the unstable/stable and unstable/neutral cases simulated using DNS (Livescu, Wei & Petersen 2011) and the unstable/stable/unstable case simulated using ILES (Ramaprabhu, Karkhanis & Lawrie 2013). The four-equation models couple equations for the mass flux a and negative density-specific volume correlation b to the K- ɛ or K- L equations, while the three-equation models use a two-fluid algebraic closure for b. The lengthscale-based models are also applied with no buoyancy production in the L equation to explore the consequences of neglecting this term. Predicted mixing widths, turbulence statistics, fields, and turbulent transport equation budgets are compared among these models to identify similarities and differences in the turbulence production, dissipation and diffusion physics represented by the closures used in these models. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  12. THE AGS-BASED SUPER NEUTRINO BEAM FACILITY CONCEPTUAL DESIGN REPORT

    SciTech Connect

    WENG,W.T.; DIWAN,M.; RAPARIA,D.

    2004-10-08

    After more than 40 years of operation, the AGS is still at the heart of the Brookhaven hadron accelerator complex. This system of accelerators presently comprises a 200 MeV linac for the pre-acceleration of high intensity and polarized protons, two Tandem Van der Graaffs for the pre-acceleration of heavy ion beams, a versatile Booster that allows for efficient injection of all three types of beams into the AGS and, most recently, the two RHIC collider rings that produce high luminosity heavy ion and polarized proton collisions. For several years now, the AGS has held the world intensity record with more than 7 x 10{sup 13} protons accelerated in a single pulse. The requirements for the proton beam for the super neutrino beam are summarized and a schematic of the upgraded AGS is shown. Since the present number of protons per fill is already close to the required number, the upgrade is based on increasing the repetition rate and reducing beam losses (to avoid excessive shielding requirements and to maintain activation of the machine components at workable level). It is also important to preserve all the present capabilities of the AGS, in particular its role as injector to RHIC. The AGS Booster was built not only to allow the injection of any species of heavy ion into the AGS but to allow a fourfold increase of the AGS intensity. It is one-quarter the circumference of the AGS with the same aperture. However, the accumulation of four Booster loads in the AGS takes about 0.6 s, and is therefore not well suited for high average beam power operation. To minimize the injection time to about 1 ms, a 1.2 GeV linac will be used instead. This linac consists of the existing warm linac of 200 MeV and a new superconducting linac of 1.0 GeV. The multi-turn H{sup -} injection from a source of 30 mA and 720 {micro}s pulse width is sufficient to accumulate 9 x 10{sup 13} particle per pulse in the AGS[10]. The minimum ramp time of the AGS to full energy is presently 0.5 s; this must

  13. 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.

  14. Novel Structural Parameters of Ig–Ag Complexes Yield a Quantitative Description of Interaction Specificity and Binding Affinity

    PubMed Central

    Marillet, Simon; Lefranc, Marie-Paule; Boudinot, Pierre; Cazals, Frédéric

    2017-01-01

    Antibody–antigen complexes challenge our understanding, as analyses to date failed to unveil the key determinants of binding affinity and interaction specificity. We partially fill this gap based on novel quantitative analyses using two standardized databases, the IMGT/3Dstructure-DB and the structure affinity benchmark. First, we introduce a statistical analysis of interfaces which enables the classification of ligand types (protein, peptide, and chemical; cross-validated classification error of 9.6%) and yield binding affinity predictions of unprecedented accuracy (median absolute error of 0.878 kcal/mol). Second, we exploit the contributions made by CDRs in terms of position at the interface and atomic packing properties to show that in general, VH CDR3 and VL CDR3 make dominant contributions to the binding affinity, a fact also shown to be consistent with the enthalpy–entropy compensation associated with preconfiguration of CDR3. Our work suggests that the affinity prediction problem could be partially solved from databases of high resolution crystal structures of complexes with known affinity. PMID:28232828

  15. Acceleration of Monte Carlo simulation of photon migration in complex heterogeneous media using Intel many-integrated core architecture.

    PubMed

    Gorshkov, Anton V; Kirillin, Mikhail Yu

    2015-08-01

    Over two decades, the Monte Carlo technique has become a gold standard in simulation of light propagation in turbid media, including biotissues. Technological solutions provide further advances of this technique. The Intel Xeon Phi coprocessor is a new type of accelerator for highly parallel general purpose computing, which allows execution of a wide range of applications without substantial code modification. We present a technical approach of porting our previously developed Monte Carlo (MC) code for simulation of light transport in tissues to the Intel Xeon Phi coprocessor. We show that employing the accelerator allows reducing computational time of MC simulation and obtaining simulation speed-up comparable to GPU. We demonstrate the performance of the developed code for simulation of light transport in the human head and determination of the measurement volume in near-infrared spectroscopy brain sensing.

  16. Linear Accelerators

    NASA Astrophysics Data System (ADS)

    Sidorin, Anatoly

    2010-01-01

    In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

  17. AGS UPGRADE TO 1-MW WITH A SUPER CONDUCTING LINAC INJECTOR.

    SciTech Connect

    RUGGIERO,A.GALESSI,J.RAPARIA,D.ROSER,T.WENG,W.

    2003-05-12

    It has been proposed to upgrade the Alternating Gradient Synchrotron (AGS) accelerator complex at the Brookhaven National Laboratory (BNL) to provide an average proton beam power of 1 MW at the energy of 28 GeV. The facility is to be primarily used as a proton driver for the production of intense neutrino beams [l]. This paper reports on the feasibility study of a proton Super-Conducting Linac (SCL) as a new injector to the AGS. The Linac beam energy is 1.3 GeV. The beam intensity is adjusted to provide the required average beam power of 1 MW at 28 GeV. The repetition rate of the SCL-AGS facility is 2.5 beam pulses per second.

  18. p54nrb/NonO and PSF promote U snRNA nuclear export by accelerating its export complex assembly.

    PubMed

    Izumi, Hiroto; McCloskey, Asako; Shinmyozu, Kaori; Ohno, Mutsuhito

    2014-04-01

    The assembly of spliceosomal U snRNPs in metazoans requires nuclear export of U snRNA precursors. Four factors, nuclear cap-binding complex (CBC), phosphorylated adaptor for RNA export (PHAX), the export receptor CRM1 and RanGTP, gather at the m(7)G-cap-proximal region and form the U snRNA export complex. Here we show that the multifunctional RNA-binding proteins p54nrb/NonO and PSF are U snRNA export stimulatory factors. These proteins, likely as a heterodimer, accelerate the recruitment of PHAX, and subsequently CRM1 and Ran onto the RNA substrates in vitro, which mediates efficient U snRNA export in vivo. Our results reveal a new layer of regulation for U snRNA export and, hence, spliceosomal U snRNP biogenesis.

  19. Can Accelerators Accelerate Learning?

    NASA Astrophysics Data System (ADS)

    Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

    2009-03-01

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ) [1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

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

    PubMed

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

    2016-01-01

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

  1. PARTICLE ACCELERATOR

    DOEpatents

    Teng, L.C.

    1960-01-19

    ABS>A combination of two accelerators, a cyclotron and a ring-shaped accelerator which has a portion disposed tangentially to the cyclotron, is described. Means are provided to transfer particles from the cyclotron to the ring accelerator including a magnetic deflector within the cyclotron, a magnetic shield between the ring accelerator and the cyclotron, and a magnetic inflector within the ring accelerator.

  2. Intermediates in assembly by photoactivation after thermally accelerated disassembly of the manganese complex of photosynthetic water oxidation.

    PubMed

    Barra, Marcos; Haumann, Michael; Loja, Paola; Krivanek, Roland; Grundmeier, Alexander; Dau, Holger

    2006-12-05

    The Mn4Ca complex bound to photosystem II (PSII) is the active site of photosynthetic water oxidation. Its assembly involves binding and light-driven oxidation of manganese, a process denoted as photoactivation. The disassembly of the Mn complex is a thermally activated process involving distinct intermediates. Starting from intermediate states of the disassembly, which was initiated by a temperature jump to 47 degrees C, we photoactivated PSII membrane particles and monitored the activity recovery by O2 polarography and delayed chlorophyll fluorescence measurements. Oxidation state and structural features of the formed intermediates of the Mn complex were assayed by X-ray absorption spectroscopy at the Mn K-edge. The photoactivation time courses, which exhibit a lag phase characteristic of intermediate formation only when starting with the apo-PSII, suggest that within approximately 5 min of photoactivation of apo-PSII, a binuclear Mn complex is formed. It is proposed that a MnIII2(di-mu-oxo) complex is a key intermediate both in the disassembly and in the assembly reaction paths.

  3. Complexation of the vulcanization accelerator tetramethylthiuram disulfide and related molecules with zinc compounds including zinc oxide clusters (Zn4O4).

    PubMed

    Steudel, Ralf; Steudel, Yana; Wong, Ming Wah

    2008-01-01

    Zinc chemicals are used as activators in the vulcanization of organic polymers with sulfur to produce elastic rubbers. In this work, the reactions of Zn(2+), ZnMe(2), Zn(OMe)(2), Zn(OOCMe)(2), and the heterocubane cluster Zn(4)O(4) with the vulcanization accelerator tetramethylthiuram disulfide (TMTD) and with the related radicals and anions Me(2)NCS(2)(*), Me(2)NCS(3)(*), Me(2)NCS(2)(-), and Me(2)NCS(3)(-) have been studied by quantum chemical methods at the MP2/6-31+G(2df,p)//B3LYP/6-31+G* level of theory. More than 35 zinc complexes have been structurally characterized and the energies of formation from their components calculated for the first time. The binding energy of TMTD as a bidendate ligand increases in the order ZnMe(2)complexes with the radicals Me(2)NCS(2)(*) and Me(2)NCS(3)(*). Dissociation of the TMTD molecule at the S-S bond on reaction with the Zn(4)O(4) cluster is predicted to be strongly exothermic, in sharp contrast to the endothermic S-S bond dissociation of the free molecule. The same holds for tetramethylthiuram trisulfide (TMTT). Surprisingly, the resulting complexes contain Zn-S as well as S-O bonds. The Zn(4)O(4) nanocluster serves here as a model for bulk zinc oxide used as an activator in rubber vulcanization by sulfur. The further uptake of sulfur atoms by the various complexes from S(8) or TMTD with formation of species derived from the radical Me(2)NCS(3)(*) or the trithiocarbamate anion Me(2)NCS(3)(-) is endothermic for mono- and dinuclear zinc dithiocarbamate (dtc) complexes such as [Zn(dtc)(2)] and [Zn(2)(dtc)(4)], but exothermic in the case of polynuclear zinc oxide species containing bridging ligands as in [Zn(4)O(4)(mu-S(2)CNMe(2))] and [Zn(4)O(4)(mu-dtc)]. Therefore, zinc oxide as a polynuclear species is predicted to promote the formation of trisulfido complexes, which are generally assumed to serve as catalysts for the transfer of

  4. RHIC injector complex online model status and plans

    SciTech Connect

    Schoefer,V.; Ahrens, L.; Brown, K.; Morris, J.; Nemesure, S.

    2009-05-04

    An online modeling system is being developed for the RHIC injector complex, which consists of the Booster, the AGS and the transfer lines connecting the Booster to the AGS and the AGS to RHIC. Historically the injectors have been operated using static values from design specifications or offline model runs, but tighter beam optics constraints required by polarized proton operations (e.g, accelerating with near-integer tunes) have necessitated a more dynamic system. An online model server for the AGS has been implemented using MAD-X [1] as the model engine, with plans to extend the system to the Booster and the injector transfer lines and to add the option of calculating optics using the Polymorphic Tracking Code (PTC [2]) as the model engine.

  5. Charge transfer initiated nitroxyl chemistry on free silver clusters Ag{sub 2-5}{sup-} : size effects and magic complexes.

    SciTech Connect

    Hagen, J.; Socaciu-Sieberg, L. D.; LeRoux, J.; Popolan, D.; Vajda, S.; Bernhardt, T. M.; Woste, L.; Chemistry; Freie Univ.; Univ. Ulm

    2007-01-01

    The reactivity of small silver cluster anions Ag{sub 2--5}- toward nitric oxide and mixtures of nitric oxide with carbon monoxide is investigated under multi-collision conditions in a radio frequency octopole ion trap at temperatures of 100 and 300 K. A strongly cluster size dependent reaction behavior is observed, where reactive fragmentation dominates for clusters with four or fewer atoms and only Ag{sub 5}- is able to form reaction products without dissociation of the metal cluster. The decisive role of charge transfer in the NO bond breakage, NO oxidation, and the formation of free NO{sub 2}{sup -} and N{sub 2}O{sub 4}{sup -} ions, as well as NxO(y>x)-ligands on the silver clusters is discussed. The mass spectrometric data reveal the particular stability of the reaction products AgN{sub 2}O{sub 4}{sup -} and Ag{sub 3}NO{sup -}. The reaction product mass spectra obtained for Ag{sub 5}{sup -} in the presence of NO and CO show the depletion of the NxO(y>x)-ligands on the metal cluster possibly involving the oxidation of CO to CO2.

  6. Accelerating discovery for complex neurological and behavioral disorders through systems genetics and integrative genomics in the laboratory mouse.

    PubMed

    Bubier, Jason A; Chesler, Elissa J

    2012-04-01

    Recent advances in systems genetics and integrative functional genomics have greatly improved the study of complex neurological and behavioral traits. The methods developed for the integrated characterization of new, high-resolution mouse genetic reference populations and systems genetics enable behavioral geneticists an unprecedented opportunity to address questions of the molecular basis of neurological and psychiatric disorders and their comorbidities. Integrative genomics augment these strategies by enabling rapid informatics-assisted candidate gene prioritization, cross-species translation, and mechanistic comparison across related disorders from a wealth of existing data in mouse and other model organisms. Ultimately, through these complementary approaches, finding the mechanisms and sources of genetic variation underlying complex neurobehavioral disease related traits is becoming tractable. Furthermore, these methods enable categorization of neurobehavioral disorders through their underlying biological basis. Together, these model organism-based approaches can lead to a refinement of diagnostic categories and targeted treatment of neurological and psychiatric disease.

  7. 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.

  8. 20% PARTIAL SIBERIAN SNAKE IN THE AGS.

    SciTech Connect

    Huang, H; Bai, M; Brown, K A; Glenn, W; Luccio, A U; Mackay, W W; Montag, C; Ptitsyn, V; Roser, T; Tsoupas, N; Zeno, K; Ranjbar, V; Spinka, H; Underwood, D

    2002-11-06

    An 11.4% partial Siberian snake was used to successfully accelerate polarized proton through a strong intrinsic depolarizing spin resonance in the AGS. No noticeable depolarization was observed. This opens up the possibility of using a 20% to 30% partial Siberian snake in the AGS to overcome all weak and strong depolarizing spin resonances. Some design and operation issues of the new partial Siberian snake are discussed.

  9. Synthesis, structures and DFT calculations of 2-(4,6-dimethyl pyrimidyl)selenolate complexes of Cu(I), Ag(I) and Au(I) and their conversion into metal selenide nanocrystals.

    PubMed

    Sharma, Rakesh K; Wadawale, Amey; Kedarnath, G; Manna, Debashree; Ghanty, Tapan K; Vishwanadh, B; Jain, Vimal K

    2014-05-07

    The complexes [M{SeC4H(Me-4,6)2N2}]6 (M = Cu (1), Ag (2)) and [Au{SeC4H(Me-4,6)2N2}(PEt3)] (3) have been prepared and characterized by elemental analyses, UV-vis, NMR ((1)H, (13)C, (77)Se) spectroscopy and single crystal X-ray diffraction. The crystal structures of [Cu{SeC4H(Me-4,6)2N2}]6·H2O (1·H2O), [Ag{SeC4H(Me-4,6)2N2}]6·6MeOH·H2O (2·6MeOH·H2O) and [Au{SeC4H(Me-4,6)2N2}(PEt3)] (3) revealed that their metal centers acquire distorted square-pyramidal, trigonal and linear geometries, respectively. DFT calculations have been carried out to rationalize nuclearity in copper(i) chalcogenolate complexes. The calculations suggest that there is hardly any energy difference between the tetrameric and hexameric forms. Thermal behavior of [Cu{SeC4H(Me-4,6)2N2}]6 was studied by thermogravimetric analysis. Thermolysis of [M{SeC4H(Me-4,6)2N2}]6 (M = Cu, Ag) in 1-dodecanethiol (DDT) at 150 °C gave a cubic phase of Cu7Se4 and an orthorhombic phase of Ag2Se, respectively. Copper selenide (Cu7Se4) thin films were deposited on glass and silicon substrates by using [Cu{SeC4H(Me-4,6)2N2}]6 at 400 °C by AACVD.

  10. Final report of CCAUV.V-K3: key comparison in the field of acceleration on the complex charge sensitivity

    NASA Astrophysics Data System (ADS)

    Qiao, Sun; Lifeng, Yang; Bartoli, Claire; Veldman, Ian; Ripper, Gustavo P.; Bruns, Thomas; Rask Licht, Torben; Kolasa, Joanna; Hof, Christian; Silva Pineda, Guillermo; Dickinson, Laurence; Ota, Akihiro; Cheung, Wan Sup; Yankovsky, Alexander; Shan, Cui

    2017-01-01

    This is the final report for CIPM key comparison CCAUV.V-K3 in the area of 'vibration' (quantity of acceleration). The aim of this comparison was to measure the voltage sensitivity of one accelerometer standard set with primary means at 27 frequencies from 0.1 Hz to 40 Hz. Fourteen Metrology Institutes from five RMOs have participated in the comparison with National Institute of Metrology, P.R. China as pilot lab and Laboratoire National de Métrologie et d'Essais and National Metrology Institute of South Africa as co-pilot labs. One quartz-flexure servo accelerometer of single-ended type and a signal conditioner was circulated among the participants. All but one of the participating laboratories provided their calibration results, which were mostly consistent within their declared expanded uncertainties for magnitude results. Only two participants failed to contribute to the KCRV values calculated for five frequencies. For phase shift, three participants could not contribute to the calculation of the KCRV values in a total of sixteen frequencies. This first low-frequency vibration key comparison revealed the current calibration capabilities of the fourteen participants of five RMOs. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCAUV, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. 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.

  12. High binding yet accelerated guest rotation within a cucurbit[7]uril complex. Toward paramagnetic gyroscopes and rolling nanomachines

    NASA Astrophysics Data System (ADS)

    Casano, G.; Poulhès, F.; Tran, T. K.; Ayhan, M. M.; Karoui, H.; Siri, D.; Gaudel-Siri, A.; Rockenbauer, A.; Jeschke, G.; Bardelang, D.; Tordo, P.; Ouari, O.

    2015-07-01

    The (15-oxo-3,7,11-triazadispiro[5.1.5.3]hexadec-7-yl)oxidanyl, a bis-spiropiperidinium nitroxide derived from TEMPONE, can be included in cucurbit[7]uril to form a strong (Ka ~ 2 × 105 M-1) CB[7]@bPTO complex. EPR and MS spectra, DFT calculations, and unparalleled increased resistance (a factor of ~103) toward ascorbic acid reduction show evidence of deep inclusion of bPTO inside CB[7]. The unusual shape of the CB[7]@bPTO EPR spectrum can be explained by an anisotropic Brownian rotational diffusion, the global tumbling of the complex being slower than rotation of bPTO around its ``long molecular axis'' inside CB[7]. The CB[7] (stator) with the encapsulated bPTO (rotator) behaves as a supramolecular paramagnetic rotor with increased rotational speed of the rotator that has great potential for advanced nanoscale machines requiring wheels such as cucurbiturils with virtually no friction between the wheel and the axle for optimum wheel rotation (i.e. nanopulleys and nanocars).The (15-oxo-3,7,11-triazadispiro[5.1.5.3]hexadec-7-yl)oxidanyl, a bis-spiropiperidinium nitroxide derived from TEMPONE, can be included in cucurbit[7]uril to form a strong (Ka ~ 2 × 105 M-1) CB[7]@bPTO complex. EPR and MS spectra, DFT calculations, and unparalleled increased resistance (a factor of ~103) toward ascorbic acid reduction show evidence of deep inclusion of bPTO inside CB[7]. The unusual shape of the CB[7]@bPTO EPR spectrum can be explained by an anisotropic Brownian rotational diffusion, the global tumbling of the complex being slower than rotation of bPTO around its ``long molecular axis'' inside CB[7]. The CB[7] (stator) with the encapsulated bPTO (rotator) behaves as a supramolecular paramagnetic rotor with increased rotational speed of the rotator that has great potential for advanced nanoscale machines requiring wheels such as cucurbiturils with virtually no friction between the wheel and the axle for optimum wheel rotation (i.e. nanopulleys and nanocars). Electronic

  13. High binding yet accelerated guest rotation within a cucurbit[7]uril complex. Toward paramagnetic gyroscopes and rolling nanomachines.

    PubMed

    Casano, G; Poulhès, F; Tran, T K; Ayhan, M M; Karoui, H; Siri, D; Gaudel-Siri, A; Rockenbauer, A; Jeschke, G; Bardelang, D; Tordo, P; Ouari, O

    2015-07-28

    The (15-oxo-3,7,11-triazadispiro[5.1.5.3]hexadec-7-yl)oxidanyl, a bis-spiropiperidinium nitroxide derived from TEMPONE, can be included in cucurbit[7]uril to form a strong (K(a)∼ 2 × 10(5) M(-1)) CB[7]@bPTO complex. EPR and MS spectra, DFT calculations, and unparalleled increased resistance (a factor of ∼10(3)) toward ascorbic acid reduction show evidence of deep inclusion of bPTO inside CB[7]. The unusual shape of the CB[7]@bPTO EPR spectrum can be explained by an anisotropic Brownian rotational diffusion, the global tumbling of the complex being slower than rotation of bPTO around its "long molecular axis" inside CB[7]. The CB[7] (stator) with the encapsulated bPTO (rotator) behaves as a supramolecular paramagnetic rotor with increased rotational speed of the rotator that has great potential for advanced nanoscale machines requiring wheels such as cucurbiturils with virtually no friction between the wheel and the axle for optimum wheel rotation (i.e. nanopulleys and nanocars).

  14. 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.

  15. Programmed improvements of the alternating gradient synchrotron complex at Brookhaven National Laboratory, Upton, New York. Environmental assessment

    SciTech Connect

    1994-03-01

    The purpose and need for DOE to undertake the actions described in this document are to improve the efficiency of the Alternating Gradient Synchrotron (AGS) complex. Benefits would include optimization of the AGS scientific program, increased high-energy and nuclear physics experimentation, improved health and safety conditions for workers and users, reduced impact on the environment and the general public, energy conservation, decreased generation of hazardous and radioactive wastes, and completion of actions required to permit the AGS to be the injector to the Relativistic Heavy Ion Collider (RHIC)., Improved efficiency is defined as increasing the AGS`s capabilities to capture and accelerate the proton intensity transferred to the AGS from the AGS booster. Improved capture of beam intensity would reduce the beam losses which equate to lost scientific opportunity for study and increased potential for radiation doses to workers and the general public. The action would also refurbish magnets used in the transfer tunnel which connects the AGS complex to RHIC to permit smooth injection of beam into the RHIC accelerator. These magnets were previously used to direct beam to fixed targets for high energy physics studies but have hot received proper maintenance to be reliable as injectors to RHIC. The document describes alternative actions, the affected environment, and environmental impacts.

  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. Future accelerators (?)

    SciTech Connect

    John Womersley

    2003-08-21

    I describe the future accelerator facilities that are currently foreseen for electroweak scale physics, neutrino physics, and nuclear structure. I will explore the physics justification for these machines, and suggest how the case for future accelerators can be made.

  18. 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.

  19. Mono and binuclear Ag(I), Cu(II), Zn(II) and Hg(II) complexes of a new azo-azomethine as ligand: synthesis, potentiometric, spectral and thermal studies.

    PubMed

    Ahmed, Ibrahim S; Moustafa, Moustafa M; Abd El Aziz, Mohamed M

    2011-05-01

    New azo-azomethine dyes were prepared by reaction of p-aminobenzoic acid, o-anisidine, o-nitroaniline, and p-bromoaniline with salicylaldehyde respectively to form azo compounds and then condensation by urea to form 4-(R-arylazo 2-salicylaldene)-urea azo-azomethine derivatives (I(a-d)). The complexes of these ligands with Ag(I), Cu(II), Zn(II) and Hg(II) metal ions were prepared. The structure of the free ligands and their complexes were characterized by using elemental analysis (C, H, N), (1)H NMR, IR and UV-Vis-spectra. The proton dissociation constants of the ligands and the stability constant of their complexes have been determined potentiometrically in 40% (v/v) alcohol-water medium as well as the stoichiometry of complexes were determined conductometrically. The data reveal that the stoichiometries for all complexes were prepared in molar ratios (1:1) and (1:2) (M:L). The electrolytic and nonelectrolytic natures of the complexes were assigned based on molar conductance measurements. The thermogravimetric (TG), and differential thermal analyses (DTA) were studied in nitrogen atmosphere with heating rate 10°C/min. The kinetic and thermodynamic parameters for thermal decomposition of complexes have been calculated by graphical method using Coats-Redfern (CR) method.

  20. Ag@AgHPW as a plasmonic catalyst for visible-light photocatalytic degradation of environmentally harmful organic pollutants

    SciTech Connect

    Zhou, Wenhui; Cao, Minhua Li, Na; Su, Shuangyue; Zhao, Xinyu; Wang, Jiangqiang; Li, Xianghua; Hu, Changwen

    2013-06-01

    Graphical abstract: Ag@Ag{sub x}H{sub 3−x}PW12O40 (Ag@AgHPW) nanoparticles (NPs), a new visible-light driven plasmonic photocatalyst, are prepared by a green photoreduction strategy without the addition of any surfactant, which show a high activity and stability for the degradation of methyl blue (MB) under visible light irradiation. - Highlights: • A new visible-light driven photocatalyst Ag@Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} was designed. • The photocatalyst shows a high activity for the degradation of methyl blue. • The high activity can be ascribed to the synergy of photoexcited AgHPW and Ag. - Abstract: Ag@Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} (Ag@AgHPW) nanoparticles (NPs), a new visible-light driven plasmonic photocatalyst, are prepared by a green photoreduction strategy without the addition of any surfactant. They show strong absorption in the visible region because of the localized surface plasmon resonance (LSPR) of Ag NPs. This plasmonic photocatalyst shows a high activity and stability for the degradation of methyl blue (MB) under visible light irradiation, which could be attributed to the highly synergy of photoexcited Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} (AgHPW) and plasmon-excited Ag NPs and the confinement effects at interfaces between polyoxometalates (POMs) and silver. POM anions have redox ability and high photocatalytic activity, whereas Ag NPs could effectively accelerate the separation of electrons and holes, both of which contribute to their high activity.

  1. Complexity.

    PubMed

    Gómez-Hernández, J Jaime

    2006-01-01

    It is difficult to define complexity in modeling. Complexity is often associated with uncertainty since modeling uncertainty is an intrinsically difficult task. However, modeling uncertainty does not require, necessarily, complex models, in the sense of a model requiring an unmanageable number of degrees of freedom to characterize the aquifer. The relationship between complexity, uncertainty, heterogeneity, and stochastic modeling is not simple. Aquifer models should be able to quantify the uncertainty of their predictions, which can be done using stochastic models that produce heterogeneous realizations of aquifer parameters. This is the type of complexity addressed in this article.

  2. Antibacterial Activity and Cytotoxicity of Silver(I) Complexes of Pyridine and (Benz)Imidazole Derivatives. X-ray Crystal Structure of [Ag(2,6-di(CH2OH)py)2]NO3.

    PubMed

    Kalinowska-Lis, Urszula; Felczak, Aleksandra; Chęcińska, Lilianna; Szabłowska-Gadomska, Ilona; Patyna, Emila; Małecki, Maciej; Lisowska, Katarzyna; Ochocki, Justyn

    2016-01-28

    Selected aspects of the biological activity of a series of six nitrate silver(I) complexes with pyridine and (benz)imidazole derivatives were investigated. The present study evaluated the antibacterial activities of the complexes against three Gram-negative strains: Pseudomonas aeruginosa ATCC 15442, Escherichia coli ATCC 25922 and Proteus hauseri ATCC 13315. The results were compared with those of silver nitrate, a silver sulfadiazine drug and appropriate ligands. The most significant antibacterial properties were exerted by silver(I) complexes containing benzimidazole derivatives. The cytotoxic activity of the complexes was examined against B16 (murine melanoma) and 10T1/2 (murine fibroblasts) cells. All of the tested silver(I) compounds were not toxic to fibroblast cells in concentration inhibited cancer cell (B16) viability by 50%, which ranged between 2.44-28.65 µM. The molecular and crystal structure of silver(I) complex of 2,6-di(hydroxymethyl)pyridine was determined by single-crystal X-ray diffraction analysis. The most important features of the crystal packing and intermolecular non-covalent interactions in the Ag(I) complex were quantified via Hirshfeld surface analysis.

  3. Effect of cysteine and humic acids on bioavailability of Ag from Ag nanoparticles to a freshwater snail

    USGS Publications Warehouse

    Luoma, Samuel N.; Tasha Stoiber,; Croteau, Marie-Noele; Isabelle Romer,; Ruth Merrifeild,; Lead, Jamie

    2016-01-01

    Metal-based engineered nanoparticles (NPs) will undergo transformations that will affect their bioavailability, toxicity and ecological risk when released to the environment, including interactions with dissolved organic material. The purpose of this paper is to determine how interactions with two different types of organic material affect the bioavailability of silver nanoparticles (AgNPs). Silver uptake rates by the pond snail Lymnaea stagnalis were determined after exposure to 25 nmol l-1 of Ag as PVP AgNPs, PEG AgNPs or AgNO3, in the presence of either Suwannee River humic acid or cysteine, a high-affinity thiol-rich organic ligand. Total uptake rate of Ag from the two NPs was either increased or not strongly affected in the presence of 1 – 10 mg 1-1 humic acid. Humic substances contain relatively few strong ligands for Ag explaining their limited effects on Ag uptake rate. In contrast, Ag uptake rate was substantially reduced by cysteine. Three components of uptake from the AgNPs were quantified in the presence of cysteine using a biodynamic modeling approach: uptake of dissolved Ag released by the AgNPs, uptake of a polymer or large (>3kD) Ag-cysteine complex and uptake of the nanoparticle itself. Addition of 1:1 Ag:cysteine reduced concentrations of dissolved Ag, which contributed to, but did not fully explain the reductions in uptake. A bioavailable Ag-cysteine complex (> 3kD) appeared to be the dominant avenue of uptake from both PVP AgNPs and PEG AgNPs in the presence of cysteine. Quantifying the different avenues of uptake sets the stage for studies to assess toxicity unique to NPs.

  4. New insight into daylight photocatalysis of AgBr@Ag: synergistic effect between semiconductor photocatalysis and plasmonic photocatalysis.

    PubMed

    Jiang, Jing; Li, Hao; Zhang, Lizhi

    2012-05-14

    Noble metal nanoparticles (NPs) are often used as electron scavengers in conventional semiconductor photocatalysis to suppress electron-hole (e(-)-h(+) ) recombination and promote interfacial charge transfer, and thus enhance photocatalytic activity of semiconductors. In this contribution, it is demonstrated that noble metal NPs such as Ag NPs function as visible-light harvesting and electron-generating centers during the daylight photocatalysis of AgBr@Ag. Novel Ag plasmonic photocatalysis could cooperate with the conventional AgBr semiconductor photocatalysis to enhance the overall daylight activity of AgBr@Ag greatly because of an interesting synergistic effect. After a systematic investigation of the daylight photocatalysis mechanism of AgBr@Ag, the synergistic effect was attributed to surface plasmon resonance induced local electric field enhancement on Ag, which can accelerate the generation of e(-)-h(+) pairs in AgBr, so that more electrons are produced in the conduction band of AgBr under daylight irradiation. This study provides new insight into the photocatalytic mechanism of noble metal/semiconductor systems as well as the design and fabrication of novel plasmonic photocatalysts.

  5. 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.

  6. Low-complexity feed-forward carrier phase estimation for M-ary QAM based on phase search acceleration by quadratic approximation.

    PubMed

    Xiang, Meng; Fu, Songnian; Deng, Lei; Tang, Ming; Shum, Perry; Liu, Deming

    2015-07-27

    Blind phase search (BPS) algorithm for M-QAM has excellent tolerance to laser linewidth at the expense of rather high computation complexity (CC). Here, we first theoretically obtain the quadratic relationship between the test angle and corresponding distance matric during the BPS implementation. Afterwards, we propose a carrier phase estimation (CPE) based on a two-stage BPS with quadratic approximation (QA). Instead of searching the phase blindly with fixed step-size for the BPS algorithm, QA can significantly accelerate the speed of phase searching. As a result, a group factor of 2.96/3.05, 4.55/4.67 and 2.27/2.3 (in the form of multipliers/adders) reduction of CC is achieved for 16QAM, 64QAM and 256QAM, respectively, in comparison with the traditional BPS scheme. Meanwhile, a guideline for determining the summing filter block length is put forward during performance optimization. Under the condition of optimum filter block length, our proposed scheme shows similar performance as traditional BPS scheme. At 1 dB required E(S)/N(0) penalty @ BER = 10(-2), our proposed CPE scheme can tolerate a times symbol duration productΔf⋅T(S) of 1.7 × 10(-4), 6 × 10(-5) and 1.5 × 10(-5) for 16/64/256-QAM, respectively.

  7. 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.

  8. Laser-induced transformation of supramolecular complexes: approach to controlled formation of hybrid multi-yolk-shell Au-Ag@a-C:H nanostructures

    PubMed Central

    Manshina, A. A.; Grachova, E. V.; Povolotskiy, A. V.; Povolotckaia, A. V.; Petrov, Y. V.; Koshevoy, I. O.; Makarova, A. A.; Vyalikh, D. V.; Tunik, S. P.

    2015-01-01

    In the present work an efficient approach of the controlled formation of hybrid Au–Ag–C nanostructures based on laser-induced transformation of organometallic supramolecular cluster compound is suggested. Herein the one-step process of the laser-induced synthesis of hybrid multi-yolk-shell Au-Ag@a-C:H nanoparticles which are bimetallic gold-silver subnanoclusters dispersed in nanospheres of amorphous hydrogenated a-C:H carbon is reported in details. It has been demonstrated that variation of the experimental parameters such as type of the organometallic precursor, solvent, deposition geometry and duration of laser irradiation allows directed control of nanoparticles’ dimension and morphology. The mechanism of Au-Ag@a-C:H nanoparticles formation is suggested: the photo-excitation of the precursor molecule through metal-to-ligand charge transfer followed by rupture of metallophilic bonds, transformation of the cluster core including red-ox intramolecular reaction and aggregation of heterometallic species that results in the hybrid metal/carbon nanoparticles with multi-yolk-shell architecture formation. It has been found that the nanoparticles obtained can be efficiently used for the Surface-Enhanced Raman Spectroscopy label-free detection of human serum albumin in low concentration solution. PMID:26153347

  9. 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.

  10. 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.

  11. Photoelectron imaging and theoretical study on the structure and chemical binding of the mixed-ligand M(I) complexes, [HMSH]{sup −} (M = Cu, Ag, and Au)

    SciTech Connect

    Qin, Zhengbo; Liu, Zhiling; Cong, Ran; Xie, Hua; Tang, Zichao E-mail: fanhj@dicp.ac.cn; Fan, Hongjun E-mail: fanhj@dicp.ac.cn

    2014-03-21

    We have reported a combined photoelectron imaging and theoretical study on gaseous mixed-ligand M(I) complexes of [HMSH]{sup −} (M = Cu, Ag, and Au). With the aid of Franck-Condon simulations, vibrationally resolved photoelectron spectra yield accurate electron affinities of 3.269(6), 3.669(10), and 3.591(6) eV for [HCuSH], [HAgSH], and [HAuSH], respectively. And low-frequency modes are observed: 368(12) cm{sup −1} for [HCuSH], 286(12) cm{sup −1} for [HAgSH], and 327(12) cm{sup −1} for [HAuSH], respectively. Extensive theoretical calculations are performed to aid in the spectral assignments and the calculated values agree well with the experimental observations. Although the S and H atoms have little discrepancy in electronegativity (2.20 for H and 2.54 for S), distinct bonding properties are demonstrated between H–M and M–S bond. It is revealed that there exists significant ionic bonding between M–S in [HMSH]{sup −} (M = Cu, Ag, and Au), while a gradual transition from ionic behavior between H–Cu in [HCuSH]{sup −} to quite strong covalent bonding between H–Au in [HAuSH]{sup −}, supported by a variety of chemical bonding analyses.

  12. Effects of reducing agents on the synthesis of Ag/rGO nanocomposites

    NASA Astrophysics Data System (ADS)

    Li, Yaya; Song, Qiong; Fan, Bingbing; Zhang, Rui

    2017-01-01

    A facile and rapid microwave-assisted green route has been used for the formation of Ag nanoparticles (AgNPs) and the reduction of graphene oxide (GO) simultaneously with five different reducing agents, sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium citrate, urea and ascorbic acid. The experimental results show that the structural properties and phase of Ag/reduced graphene oxide (Ag/rGO) nanocomposites are connected with reducing agent. AgNPs can be uniformly and compactly anchored on reduced GO (rGO) surface in the microwave field for 2 min by the assist of NaOH or KOH as reducing agent. The OH‑ can not only accelerate the ionization of acidic functional groups but also act as the nucleophile for Ag+. By addition of sodium citrate and urea, the GO sample remains its original structure, and Ag+ tends to form Ag2CO3, which then decomposes into Ag2O. While in the urea solution, Ag2O turns into [Ag(NH3)2]+ ions with abundant urea, then [Ag(NH3)2]+ ions are reduced to Ag0 by electrons, which leads to both Ag and Ag2O phase coexisting in the urea treated samples. In addition, it can be found that NaOH shows the best results in terms of the crystallinity and purity of Ag grains anchored on rGO surface.

  13. 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.

  14. Highly selective and sensitive determination of several antioxidants in human breast milk using high-performance liquid chromatography based on Ag(III) complex chemiluminescence detection.

    PubMed

    Ma, Li; Shi, Hongmei; Lian, Kaoqi; Diao, Yingfei; Chen, Yang; Ma, Chunling; Kang, Weijun

    2017-03-01

    Ascorbic acid (AA), uric acid (UA) and glutathione (GSH) are the most important water-soluble antioxidants. The concentrations of GSH and glutathione disulfide (GSSG) and their molar ratio are the indicators of oxidative stress. Little is known about the contents of UA, GSH and GSSG in human milk; a reliable and sensitive method to monitor the concentrations of the four compounds simultaneously in human milk is of critical importance. A new method for separation and quantification of these water-soluble antioxidants by HPLC coupled with Ag(III) chemiluminescence detector has been developed in this work with better recoveries. The antioxidants contents were determined in different times of lactation utilizing this method. The results show that the levels of AA, UA, GSH and GSH/GSSG of human colostrum are significantly higher than those of mature milk (P<0.05). It is concluded that colostrum contains more water-soluble antioxidants than mature milk.

  15. LINEAR ACCELERATOR

    DOEpatents

    Colgate, S.A.

    1958-05-27

    An improvement is presented in linear accelerators for charged particles with respect to the stable focusing of the particle beam. The improvement consists of providing a radial electric field transverse to the accelerating electric fields and angularly introducing the beam of particles in the field. The results of the foregoing is to achieve a beam which spirals about the axis of the acceleration path. The combination of the electric fields and angular motion of the particles cooperate to provide a stable and focused particle beam.

  16. Acceleration switch

    DOEpatents

    Abbin, Jr., Joseph P.; Devaney, Howard F.; Hake, Lewis W.

    1982-08-17

    The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

  17. Acceleration switch

    DOEpatents

    Abbin, J.P. Jr.; Devaney, H.F.; Hake, L.W.

    1979-08-29

    The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

  18. ION ACCELERATOR

    DOEpatents

    Bell, J.S.

    1959-09-15

    An arrangement for the drift tubes in a linear accelerator is described whereby each drift tube acts to shield the particles from the influence of the accelerating field and focuses the particles passing through the tube. In one embodiment the drift tube is splii longitudinally into quadrants supported along the axis of the accelerator by webs from a yoke, the quadrants. webs, and yoke being of magnetic material. A magnetic focusing action is produced by energizing a winding on each web to set up a magnetic field between adjacent quadrants. In the other embodiment the quadrants are electrically insulated from each other and have opposite polarity voltages on adjacent quadrants to provide an electric focusing fleld for the particles, with the quadrants spaced sufficienily close enough to shield the particles within the tube from the accelerating electric field.

  19. LINEAR ACCELERATOR

    DOEpatents

    Christofilos, N.C.; Polk, I.J.

    1959-02-17

    Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.

  20. 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.

  1. Effect of accelerator in green synthesis of silver nanoparticles.

    PubMed

    Darroudi, Majid; Ahmad, Mansor Bin; Abdullah, Abdul Halim; Ibrahim, Nor Azowa; Shameli, Kamyar

    2010-10-12

    Silver nanoparticles (Ag-NPs) were successfully synthesized in the natural polymeric matrix. Silver nitrate, gelatin, glucose, and sodium hydroxide have been used as silver precursor, stabilizer, reducing agent, and accelerator reagent, respectively. This study investigated the role of NaOH as the accelerator. The resultant products have been confirmed to be Ag-NPs using powder X-ray diffraction (PXRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The colloidal sols of Ag-NPs obtained at different volumes of NaOH show strong and different surface plasmon resonance (SPR) peaks, which can be explained from the TEM images of Ag-NPs and their particle size distribution. Compared with other synthetic methods, this work is green, rapid, and simple to use. The newly prepared Ag-NPs may have many potential applications in chemical and biological industries.

  2. Acceleration Studies

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.

    1993-01-01

    Work to support the NASA MSFC Acceleration Characterization and Analysis Project (ACAP) was performed. Four tasks (analysis development, analysis research, analysis documentation, and acceleration analysis) were addressed by parallel projects. Work concentrated on preparation for and implementation of near real-time SAMS data analysis during the USMP-1 mission. User support documents and case specific software documentation and tutorials were developed. Information and results were presented to microgravity users. ACAP computer facilities need to be fully implemented and networked, data resources must be cataloged and accessible, future microgravity missions must be coordinated, and continued Orbiter characterization is necessary.

  3. Hsp90 inhibition accelerates cell lysis. Anti-Hsp90 ribozyme reveals a complex mechanism of Hsp90 inhibitors involving both superoxide- and Hsp90-dependent events.

    PubMed

    Sreedhar, Amere Subbarao; Mihály, Katalin; Pató, Bálint; Schnaider, Tamás; Steták, Attila; Kis-Petik, Katalin; Fidy, Judit; Simonics, Tibor; Maraz, Anna; Csermely, Péter

    2003-09-12

    The 90 kDa heat shock protein, Hsp90, is an abundant molecular chaperone participating in the cytoprotection of eukaryotic cells. Here we analyzed the involvement of Hsp90 in the maintenance of cellular integrity using partial cell lysis as a measure. Inhibition of Hsp90 by geldanamycin, radicicol, cisplatin, and novobiocin induced a significant acceleration of detergent- and hypotonic shock-induced cell lysis. The concentration and time dependence of cell lysis acceleration was in agreement with the Hsp90 inhibition characteristics of the N-terminal inhibitors, geldanamycin and radicicol. Glutathione and other reducing agents partially blocked geldanamycin-induced acceleration of cell lysis but were largely ineffective with other inhibitors. Indeed, geldanamycin treatment led to superoxide production and a change in membrane fluidity. When Hsp90 content was diminished using anti-Hsp90 hammerhead ribozymes, an accelerated cell lysis was also observed. Hsp90 inhibition-induced cell lysis was more pronounced in eukaryotic (yeast, mouse red blood, and human T-lymphoma) cells than in bacteria. Our results indicate that besides the geldanamycin-induced superoxide production, and a consequent increase in cell lysis, inhibition or lack of Hsp90 alone can also compromise cellular integrity. Moreover, cell lysis after hypoxia and complement attack was also enhanced by any type of Hsp90 inhibition used, which shows that the maintenance of cellular integrity by Hsp90 is important in physiologically relevant lytic conditions of tumor cells.

  4. Silver Complexes of Dihalogen Molecules.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The perfluorohexane-soluble and donor-free silver compound Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) prepared using a facile novel route has unprecedented capabilities to form unusual and weakly bound complexes. Here, we report on the three dihalogen-silver complexes Ag(Cl2 )A, Ag(Br2 )A, and Ag(I2 )A derived from the soluble silver compound Ag(A) (characterized by single-crystal/powder XRD, Raman spectra, and quantum-mechanical calculations).

  5. Synthesis of {beta}-phase Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions nanocrystals

    SciTech Connect

    Liu, Xianli; Zhang, Jinghong; Zhang, Guilan; Jiang, Zhonghao; Jin, Dezhen

    2011-06-15

    Research highlights: {yields} Wet-chemical-chelating reaction processing has been used to synthesized A series of single {beta}-phase nano-Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions powders. {yields} Citric acid as complexing agent takes part in the process of chemical reaction and the chemical reactions can be described in this paper. {yields} The lattice parameters have been ascertained by the results of XRD. {yields} Crystalline sizes, which decrease with copper iodide concentration increasing, have been demonstrated by XRD and TEM. -- Abstract: A series of single {beta}-phase nano-Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions powders were synthesized by wet-chemical-chelating reaction processing and citric acid used as complexing agent. The Ag{sub 1-x}Cu{sub x}I powders were determined by X-ray diffraction and transmission electron microscopy. It was demonstrated that the crystalline size and lattice parameter of the Ag{sub 1-x}Cu{sub x}I powders decrease with an increase in the amount of CuI substitution. The copper in the lattice of the Ag{sub 1-x}Cu{sub x}I can effectively prevent the crystalline growth of the Ag{sub 1-x}Cu{sub x}I powders and citrate used in the Ag{sub 1-x}Cu{sub x}I powders synthesized process can accelerate single {beta}-phase crystalline structure formation.

  6. New beam instrumentation in the AGS Booster

    SciTech Connect

    Witkover, R.L.

    1991-01-01

    The AGS Booster was designed to accelerate beams from 2{times}10{sup 10} polarized protons to 1.5{times}10{sup 13} protons and heavy ions through Au{sup +33}. The range of beam parameters and the high vacuum, and radiation environment presented challenges for the beam instrumentation. Some interesting beam monitors in the Booster and transport lines, will be described. Where available, results will be presented. 21 refs., 7 figs.

  7. Particle acceleration

    NASA Technical Reports Server (NTRS)

    Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.; Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.; Ellison, D.

    1986-01-01

    Data is compiled from Solar Maximum Mission and Hinothori satellites, particle detectors in several satellites, ground based instruments, and balloon flights in order to answer fundamental questions relating to: (1) the requirements for the coronal magnetic field structure in the vicinity of the energization source; (2) the height (above the photosphere) of the energization source; (3) the time of energization; (4) transistion between coronal heating and flares; (5) evidence for purely thermal, purely nonthermal and hybrid type flares; (6) the time characteristics of the energization source; (7) whether every flare accelerates protons; (8) the location of the interaction site of the ions and relativistic electrons; (9) the energy spectra for ions and relativistic electrons; (10) the relationship between particles at the Sun and interplanetary space; (11) evidence for more than one acceleration mechanism; (12) whether there is single mechanism that will accelerate particles to all energies and also heat the plasma; and (13) how fast the existing mechanisms accelerate electrons up to several MeV and ions to 1 GeV.

  8. Plasma accelerator

    DOEpatents

    Wang, Zhehui; Barnes, Cris W.

    2002-01-01

    There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

  9. Accelerated Achievement

    ERIC Educational Resources Information Center

    Ford, William J.

    2010-01-01

    This article focuses on the accelerated associate degree program at Ivy Tech Community College (Indiana) in which low-income students will receive an associate degree in one year. The three-year pilot program is funded by a $2.3 million grant from the Lumina Foundation for Education in Indianapolis and a $270,000 grant from the Indiana Commission…

  10. ACCELERATION INTEGRATOR

    DOEpatents

    Pope, K.E.

    1958-01-01

    This patent relates to an improved acceleration integrator and more particularly to apparatus of this nature which is gyrostabilized. The device may be used to sense the attainment by an airborne vehicle of a predetermined velocitv or distance along a given vector path. In its broad aspects, the acceleration integrator utilizes a magnetized element rotatable driven by a synchronous motor and having a cylin drical flux gap and a restrained eddy- current drag cap deposed to move into the gap. The angular velocity imparted to the rotatable cap shaft is transmitted in a positive manner to the magnetized element through a servo feedback loop. The resultant angular velocity of tae cap is proportional to the acceleration of the housing in this manner and means may be used to measure the velocity and operate switches at a pre-set magnitude. To make the above-described dcvice sensitive to acceleration in only one direction the magnetized element forms the spinning inertia element of a free gyroscope, and the outer housing functions as a gimbal of a gyroscope.

  11. Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles: part 2-toxicity and Ag speciation.

    PubMed

    Bone, Audrey J; Colman, Benjamin P; Gondikas, Andreas P; Newton, Kim M; Harrold, Katherine H; Cory, Rose M; Unrine, Jason M; Klaine, Stephen J; Matson, Cole W; Di Giulio, Richard T

    2012-07-03

    To study the effects of complex environmental media on silver nanoparticle (AgNP) toxicity, AgNPs were added to microcosms with freshwater sediments and two species of aquatic plants (Potamogeton diversifolius and Egeria densa), followed by toxicity testing with microcosm surface water. Microcosms were designed with four environmental matrices in order to determine the contribution of each environmental compartment to changes in toxicity: water only (W), water + sediment (WS), water + plants (WP), and water + plants + sediment (WPS). Silver treatments included AgNPs with two different coatings, gum arabic (GA-AgNPs) or polyvinylpyrollidone (PVP-AgNPs), as well as AgNO(3). Water samples taken from the microcosms at 24 h postdosing were used in acute toxicity tests with two standard model organisms, early life stage zebrafish (Danio rerio) and Daphnia magna. Speciation of Ag in these samples was analyzed using Ag L3-edge X-ray absorption near edge spectroscopy (XANES). Silver speciation patterns for the nanoparticle treatments varied significantly by coating type. While PVP-AgNPs were quite stable and resisted transformation across all matrices (>92.4% Ag(0)), GA-AgNP speciation patterns suggest significantly higher transformation rates, especially in treatments with plants (<69.2% and <58.8% Ag(0) in WP and WPS, respectively) and moderately increased transformation with sediments (<85.6% Ag(0)). Additionally, the presence of plants in the microcosms (with and without sediments) reduced both the concentration of Ag in the water column and toxicity for all Ag treatments. Reductions in toxicity may have been related to decreased water column concentrations as well as changes in the surface chemistry of the particles induced by organic substances released from the plants.

  12. MULTIPLE SINGLE BUNCH EXTRACTION TO THE AGS SWITCHYARD.

    SciTech Connect

    BROWN,K.A.; AHRENS,L.; GASSNER,D.; GLENN,J.W.; ROSER,T.; SMITH,G.; TSOUPAS,N.; VAN ASSELT,W.; ZENO,K.

    2001-06-18

    In this report we will describe the multiple single bunch extraction system as utilized to deliver beams to the Brookhaven's Alternating Gradient Synchrotron (AGS) switchyard area. We will describe modifications of the AGS switchyard, necessary to allow it to accept bunched beam, and results of the first commissioning of this system. The AGS Switchyard has for many years been used to simultaneously deliver (unbunched) resonant extracted beam to a set of fixed target experiments. In order to accommodate new fixed target experiments which require bunched beams, a method of sending the bunched beams to the AGS Switchyard was required. In addition, by using the AGS switchyard instead of the upstream section of the Brookhaven's Relativistic Heavy Ion Collider (RHIC) injection line the accelerators can be reconfigured quickly and efficiently for filling RHIC. We will present results of the commissioning of this system, which was done in January 2001.

  13. Accelerator Facilities for Radiation Research

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.

    1999-01-01

    HSRP Goals in Accelerator Use and Development are: 1.Need for ground-based heavy ion and proton facility to understand space radiation effects discussed most recently by NAS/NRC Report (1996). 2. Strategic Program Goals in facility usage and development: -(1) operation of AGS for approximately 600 beam hours/year; (2) operation of Loma Linda University (LLU) proton facility for approximately 400 beam hours/year; (3) construction of BAF facility; and (4) collaborative research at HIMAC in Japan and with other existing or potential international facilities. 3. MOA with LLU has been established to provide proton beams with energies of 40-250 important for trapped protons and solar proton events. 4. Limited number of beam hours available at Brookhaven National Laboratory's (BNL) Alternating Gradient Synchrotron (AGS).

  14. 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.

  15. On the polarized beam acceleration in medium energy synchrotrons

    SciTech Connect

    Lee, S.Y.

    1992-12-31

    This lecture note reviews physics of spin motion in a synchrotron, spin depolarization mechanisms of spin resonances, and methods of overcoming the spin resonances during acceleration. Techniques used in accelerating polarized ions in the low/medium energy synchrotrons, such as the ZGS, the AGS, SATURNE, and the KEK PS and PS Booster are discussed. Problems related to polarized proton acceleration with snakes or partial snake are also examined.

  16. A novel hexanuclear silver(I) cluster containing a regular Ag6 ring with short Ag-Ag distances and an argentophilic interaction.

    PubMed

    Barreiro, Elena; Casas, José S; Couce, María D; Laguna, Antonio; López-de-Luzuriaga, José M; Monge, Miguel; Sánchez, Agustin; Sordo, José; Vázquez López, Ezequiel M

    2013-04-28

    The hexanuclear complex [HQ][Ag(p-mpspa)] (H2-p-mpspa = 3-(4-methoxyphenyl)-2-sulfanylpropenoic acid) was prepared by reacting the precursor [Ag(H-p-mpspa)] with diisopropylamine (Q). The complex was characterized by spectroscopic techniques and the structure was solved by a single crystal X-ray diffraction study. The crystal contains hydrogen-bonded diisopropylammonium cations and [Ag6(p-mpspa)6](6-) anions that are based on a regular Ag6 ring with each S-donor atom of the sulfanylcarboxylate ligand bridging two Ag atoms. The Ag-Ag bond distances, 2.8036(6) Å, are very short and suggest a closed shell d(10)···d(10) argentophilic interaction. To analyze the relative role of this interaction and that of the S-bridging atom the anionic [Ag6(p-mpspa)6](6-) moiety has been studied theoretically at the Hartree-Fock (HF) and 2(nd) order Møller-Plesset perturbation theory (MP2) levels on a very simple [Ag6(SH)6] A model system. A large model system [Ag6(p-mpspa)6](6-)B has also been studied by applying the ONIOM (QM/MM) approach using HF/UFF and MP2/UFF combinations as levels of theory. The six experimentally observed Ag(I)···Ag(I) supported interactions are reproduced when dispersion-type interactions are considered in the theory levels MP2 and ONIOM MP2/UFF for models A and B, respectively. The use of HF and ONIOM HF/UFF levels led to a similar hexanuclear structure but displayed a large hexagonal disposition without argentophilic contacts for both models A and B. The steric hindrance exerted by the ligands did not preclude the formation of argentophilic interactions, as observed experimentally.

  17. ACCELERATING POLARIZED PROTONS TO HIGH ENERGY.

    SciTech Connect

    BAI, M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; BEEBE-WANG, J.; BLASKIEWICZ, M.; BRAVAR, A.; BRENNAN, J.M.; BRUNO, D.; BUNCE, G.; ET AL.

    2006-10-02

    The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.

  18. Particle Accelerators in China

    NASA Astrophysics Data System (ADS)

    Zhang, Chuang; Fang, Shouxian

    As the special machines that can accelerate charged particle beams to high energy by using electromagnetic fields, particle accelerators have been widely applied in scientific research and various areas of society. The development of particle accelerators in China started in the early 1950s. After a brief review of the history of accelerators, this article describes in the following sections: particle colliders, heavy-ion accelerators, high-intensity proton accelerators, accelerator-based light sources, pulsed power accelerators, small scale accelerators, accelerators for applications, accelerator technology development and advanced accelerator concepts. The prospects of particle accelerators in China are also presented.

  19. Compact accelerator

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    2007-02-06

    A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

  20. Reaction mechanism and metal ion transformation in photocatalytic ozonation of phenol and oxalic acid with Ag(+)/TiO2.

    PubMed

    Chen, Yingying; Xie, Yongbing; Yang, Jun; Cao, Hongbin; Zhang, Yi

    2014-03-01

    Photocatalytic ozonation of phenol and oxalic acid (OA) was conducted with a Ag(+)/TiO2 catalyst and different pathways were found for the degradation of different compounds. Ag(+) greatly promoted the photocatalytic degradation of contaminants due to its role as an electron scavenger. It also accelerated the removal rate of OA in ozonation and the simultaneous process for its complex reaction with oxalate. Phenol could be degraded both in direct ozonation and photolysis, but the TOC removal rates were much higher in the simultaneous processes due to the oxidation of hydroxyl radicals resulting from synergetic effects. The sequence of photo-illumination and ozone exposure in the combined process showed quite different effects in phenol degradation and TOC removal. The synergetic effects in different combined processes were found to be highly related to the properties of the target pollutants. The color change of the solution and TEM result confirmed that Ag(+) was easily reduced and deposited on the surface of TiO2 under photo-illumination, and dissolved again into solution in the presence of ozone. This simple cycle of enrichment and distribution of Ag(+) can greatly benefit the design of advanced oxidation processes, in which the sequences of ozone and photo-illumination can be varied according to the needs for catalyst recycling and the different properties of pollutants.

  1. Laser acceleration

    NASA Astrophysics Data System (ADS)

    Tajima, T.; Nakajima, K.; Mourou, G.

    2017-02-01

    The fundamental idea of Laser Wakefield Acceleration (LWFA) is reviewed. An ultrafast intense laser pulse drives coherent wakefield with a relativistic amplitude robustly supported by the plasma. While the large amplitude of wakefields involves collective resonant oscillations of the eigenmode of the entire plasma electrons, the wake phase velocity ˜ c and ultrafastness of the laser pulse introduce the wake stability and rigidity. A large number of worldwide experiments show a rapid progress of this concept realization toward both the high-energy accelerator prospect and broad applications. The strong interest in this has been spurring and stimulating novel laser technologies, including the Chirped Pulse Amplification, the Thin Film Compression, the Coherent Amplification Network, and the Relativistic Mirror Compression. These in turn have created a conglomerate of novel science and technology with LWFA to form a new genre of high field science with many parameters of merit in this field increasing exponentially lately. This science has triggered a number of worldwide research centers and initiatives. Associated physics of ion acceleration, X-ray generation, and astrophysical processes of ultrahigh energy cosmic rays are reviewed. Applications such as X-ray free electron laser, cancer therapy, and radioisotope production etc. are considered. A new avenue of LWFA using nanomaterials is also emerging.

  2. BICEP's acceleration

    SciTech Connect

    Contaldi, Carlo R.

    2014-10-01

    The recent Bicep2 [1] detection of, what is claimed to be primordial B-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential V(φ) for the first time — if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles ε(N) as a function of e-fold N and derived posterior distributions of the primordial power spectrum P(k) and potential V(φ). We find that the Bicep2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales k∼ 10{sup -3} Mpc {sup -1}. This is in agreement with a previous detection of a suppression in the scalar power [2].

  3. A computational insight into a metal mediated pathway for the ring-opening polymerization (ROP) of lactides by an ionic {(NHC)2Ag}(+)X(-) (X = halide) type N-heterocyclic carbene (NHC) complex.

    PubMed

    Stephen, Raji; Sunoj, Raghavan B; Ghosh, Prasenjit

    2011-10-21

    A metal mediated coordination-insertion pathway for the ring-opening polymerization (ROP) of L-lactide by an ionic {(NHC)(2)Ag}(+)X(-) (X = halide) type silver complex of N-heterocyclic carbene (NHC) has been investigated using the density functional theory (DFT) method. A clear insight into the lactide insertion process could be obtained by modeling two consecutive monomer addition steps with the first one mimicking chain initiation with the second representing a propagation step. In particular, in each of the cycles, the reaction initiates with the formation of a lactide coordinated species, [1+LL] and [2+LL] that transforms into a metal bound cyclic lactide intermediate, I([1+LL]→2) and I([2+LL]→3), which subsequently ring opens to give the lactide inserted products, 2 and 3. The estimated overall activation barrier for the initiation step is 42.0 kcal mol(-1) while the same for the propagation step is 31.5 kcal mol(-1). Studies on higher monomer insertions showed a decrease in the relative product energies as anticipated for an addition polymerization pathway.

  4. Aligning "TextEvaluator"® Scores with the Accelerated Text Complexity Guidelines Specified in the Common Core State Standards. Research Report. ETS RR-15-21

    ERIC Educational Resources Information Center

    Sheehan, Kathleen M.

    2015-01-01

    The "TextEvaluator"® text analysis tool is a fully automated text complexity evaluation tool designed to help teachers, curriculum specialists, textbook publishers, and test developers select texts that are consistent with the text complexity guidelines specified in the Common Core State Standards.This paper documents the procedure used…

  5. Silver(I) complex formation with cysteine, penicillamine, and glutathione.

    PubMed

    Leung, Bonnie O; Jalilehvand, Farideh; Mah, Vicky; Parvez, Masood; Wu, Qiao

    2013-04-15

    The complex formation between silver(I) and cysteine (H2Cys), penicillamine (H2Pen), and glutathione (H3Glu) in alkaline aqueous solution was examined using extended X-ray absorption fine structure (EXAFS) and (109)Ag NMR spectroscopic techniques. The complexes formed in 0.1 mol dm(-3) Ag(I) solutions with cysteine and penicillamine were investigated for ligand/Ag(I) (L/Ag) mole ratios increasing from 2.0 to 10.0. For the series of cysteine solutions (pH 10-11) a mean Ag-S bond distance of 2.45 ± 0.02 Å consistently emerged, while for penicillamine (pH 9) the average Ag-S bond distance gradually increased from 2.40 to 2.44 ± 0.02 Å. EXAFS and (109)Ag NMR spectra of a concentrated Ag(I)-cysteine solution (C(Ag(I)) = 0.8 mol dm(-3), L/Ag = 2.2) showed a mean Ag-S bond distance of 2.47 ± 0.02 Å and δ((109)Ag) 1103 ppm, consistent with prevailing, partially oligomeric AgS3 coordinated species, while for penicillamine (C(Ag(I)) = 0.5 mol dm(-3), L/Ag = 2.0) the mean Ag-S bond distance of 2.40 ± 0.02 Å and δ((109)Ag) 922 ppm indicate that mononuclear AgS2 coordinated complexes dominate. For Ag(I)-glutathione solutions (C(Ag(I)) = 0.01 mol dm(-3), pH ∼11), mononuclear AgS2 coordinated species with a mean Ag-S bond distance of 2.36 ± 0.02 Å dominate for L/Ag mole ratios from 2.0 to 10.0. The crystal structure of the silver(I)-cysteine compound (NH4)Ag2(HCys)(Cys)·H2O (1) precipitating at pH ∼10 was solved and showed a layer structure with both AgS3 and AgS3N coordination to the cysteinate ligands. A redetermination of the crystal structure of Ag(HPen)·H2O (2) confirmed the proposed digonal AgS2 coordination environment to bridging thiolate sulfur atoms in polymeric intertwining chains forming a double helix. A survey of Ag-S bond distances for crystalline Ag(I) complexes with S-donor ligands in different AgS2, AgS2(O/N), and AgS3 coordination environments was used, together with a survey of (109)Ag NMR chemical shifts, to assist assignments of the Ag

  6. Overcoming an intrinsic depolarizing resonance with a partial snake at the Brookhaven AGS.

    SciTech Connect

    Huang, H.; Ahrens, L.; Bai, M.; Brown, K. A.; Glenn, W.; Luccio, A. U.; MacKay, W. W.; Montag, C.; Ptitsyn, V.; Roser, T.; Tsoupas, N.; Zeno, K.; Ranjbar, V.; Cadman, R. V.; Spinka, H.; Underwood, D.; High Energy Physics; BNL; Indiana Univ.

    2004-06-01

    An 11.4% partial Siberian snake was used to successfully accelerate polarized protons through a strong intrinsic depolarizing spin resonance in the Alternating Gradient Synchrotron (AGS). No noticeable depolarization was observed. This opens up the possibility of using a 20% to 30% partial Siberian snake in the AGS or other medium energy proton synchrotrons to overcome all weak and strong depolarizing spin resonances.

  7. Advanced concepts for acceleration

    SciTech Connect

    Keefe, D.

    1986-07-01

    Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)

  8. 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.

  9. Accelerators and the Accelerator Community

    SciTech Connect

    Malamud, Ernest; Sessler, Andrew

    2008-06-01

    In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.

  10. 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.

  11. 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.

  12. Latest Pleistocene and Holocene slip rates on the Lone Mountain fault: Evidence for accelerating slip in the Silver Peak-Lone Mountain extensional complex

    NASA Astrophysics Data System (ADS)

    Lifton, Zachery M.; Frankel, Kurt L.; Newman, Andrew V.

    2015-03-01

    Determining the constancy of fault slip rates over time is critical in characterizing strain distribution across plate boundaries such as the Pacific-North American plate boundary in the western U.S. We present results from the Lone Mountain fault, a normal fault within the southern Walker Lane, that suggest slip rates there may have increased approximately twofold since the late Pleistocene. We combine detailed field surficial mapping, topographic surveying, and 10Be cosmogenic nuclide exposure ages to calculate new late Pleistocene and Holocene slip rates on the Lone Mountain fault. Alluvial fans with ages of 14.6 ± 1.4 ka and 8.0 ± 0.9 ka are vertically offset 10.2 ± 0.6 m and 4.7 ± 0.6 m, respectively, yielding vertical slip rates of 0.7 ± 0.1 mm/yr and 0.6 ± 0.1 mm/yr. These slip rates are faster than the rates of 0.1 to 0.4 mm/yr from earlier in the Pleistocene, defining a pattern of accelerating slip on the Lone Mountain fault over a timescale of 104 years. The possibility of accelerating slip rates in parts of the Walker Lane partially reconciles the observed discrepancy between long- and short-term slip rates in this region and elucidates the distribution of strain across an evolving plate boundary.

  13. BNL AGS - a context for kaon factories

    SciTech Connect

    Littenberg, L.S.

    1983-05-01

    Figure 1 shows the Brookhaven site with the AGS-CBA complex highlighted. In this photograph the AGS is dwarfed by CBA and indeed during the past few years future plans for particle physics at BNL have been dominated by this enormous project. However, very recently interest in future physics use of the AGS has undergone a strong revival. Indeed, since the beginning of this year, two projects for augmenting the AGS have been proposed. Such projects could keep the AGS viable as a research machine for many years to come. In general such schemes will also improve the performance and increase the versatility of the CBA, and so are doubly valuable. It should be kept in mind that in spite of the fact the AGS has been perhaps the most fruitful machine in the history of high energy physics, its full capacities have never been exploited. Even without improvements at least one generation of rare K decay experiments beyond those currently launched seems feasible. Beyond that a major effort at any of the experiments discussed above could take it to the point where it would be limited by intrinsic physics background. To pursue a full program of physics at this level one would want to increase the intensity of the AGS as described. A ten-fold increase in K flux would remove such experiments from the category of all-out technological assaults and render them manageable by reasonably small groups of physicists. In addition, certain other, cleaner experiments, e.g., K/sub L//sup 0/ ..-->.. e/sup +/e/sup -/ or e/sup +/e/sup -/..pi../sup 0/, could be pushed to limits unobtainable at the present AGS. The increased flux would also be welcomed by the neutrino and hypernuclear physics programs. Even experiments which do not at present require higher fluxes would benefit through the availability of purer beams and cleaner conditions.

  14. Impact accelerations

    NASA Technical Reports Server (NTRS)

    Vongierke, H. E.; Brinkley, J. W.

    1975-01-01

    The degree to which impact acceleration is an important factor in space flight environments depends primarily upon the technology of capsule landing deceleration and the weight permissible for the associated hardware: parachutes or deceleration rockets, inflatable air bags, or other impact attenuation systems. The problem most specific to space medicine is the potential change of impact tolerance due to reduced bone mass and muscle strength caused by prolonged weightlessness and physical inactivity. Impact hazards, tolerance limits, and human impact tolerance related to space missions are described.

  15. Synthesis of biocompatible AuAgS/Ag2S nanoclusters and their applications in photocatalysis and mercury detection

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Chen, Shenna; Zhang, Lingyang; Huang, Haowen; Liu, Fengping; Liu, Xuanyong

    2014-12-01

    In this paper, a facile approach for preparation of AuAgS/Ag2S nanoclusters was developed. The unique AuAgS/Ag2S nanoclusters capped with biomolecules exhibit interesting excellent optical and catalytic properties. The fluorescent AuAgS/Ag2S nanoclusters show tunable luminescence depending on the nanocluster size. The apoptosis assay demonstrated that the AuAgS/Ag2S nanoclusters showed low cytotoxicity and good biocompatibility. Therefore, the nanoclusters can be used not only as a probe for labeling cells but also for their photocatalytic activity for photodegradation of organic dye. Moreover, a highly selective and sensitive assay for detection of mercury including Hg2+ and undissociated mercury complexes was developed based on the quenching fluorescent AuAgS/Ag2S nanoclusters, which provides a promising approach for determining various forms of Hg in the mercury-based compounds in environment. These unique nanoclusters may have potential applications in biological labeling, sensing mercury, and photodegradation of various organic pollutants in waste water.

  16. @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.

  17. Acceleration during magnetic reconnection

    SciTech Connect

    Beresnyak, Andrey; Li, Hui

    2015-07-16

    The presentation begins with colorful depictions of solar x-ray flares and references to pulsar phenomena. Plasma reconnection is complex, could be x-point dominated or turbulent, field lines could break due to either resistivity or non-ideal effects, such as electron pressure anisotropy. Electron acceleration is sometimes observed, and sometimes not. One way to study this complex problem is to have many examples of the process (reconnection) and compare them; the other way is to simplify and come to something robust. Ideal MHD (E=0) turbulence driven by magnetic energy is assumed, and the first-order acceleration is sought. It is found that dissipation in big (length >100 ion skin depths) current sheets is universal and independent on microscopic resistivity and the mean imposed field; particles are regularly accelerated while experiencing curvature drift in flows driven by magnetic tension. One example of such flow is spontaneous reconnection. This explains hot electrons with a power-law tail in solar flares, as well as ultrashort time variability in some astrophysical sources.

  18. Novel durable bio-photocatalyst purifiers, a non-heterogeneous mechanism: accelerated entrapped dye degradation into structural polysiloxane-shield nano-reactors.

    PubMed

    Dastjerdi, Roya; Montazer, Majid; Shahsavan, Shadi; Böttcher, Horst; Moghadam, M B; Sarsour, Jamal

    2013-01-01

    This research has designed innovative Ag/TiO(2) polysiloxane-shield nano-reactors on the PET fabric to develop novel durable bio-photocatalyst purifiers. To create these very fine nano-reactors, oppositely surface charged multiple size nanoparticles have been applied accompanied with a crosslinkable amino-functionalized polysiloxane (XPs) emulsion. Investigation of photocatalytic dye decolorization efficiency revealed a non-heterogeneous mechanism including an accelerated degradation of entrapped dye molecules into the structural polysiloxane-shield nano-reactors. In fact, dye molecules can be adsorbed by both Ag and XPs due to their electrostatic interactions and/or even via forming a complex with them especially with silver NPs. The absorbed dye and active oxygen species generated by TiO(2) were entrapped by polysiloxane shelter and the presence of silver nanoparticles further attract the negative oxygen species closer to the adsorbed dye molecules. In this way, the dye molecules are in close contact with concentrated active oxygen species into the created nano-reactors. This provides an accelerated degradation of dye molecules. This non-heterogeneous mechanism has been detected on the sample containing all of the three components. Increasing the concentration of Ag and XPs accelerated the second step beginning with an enhanced rate. Further, the treated samples also showed an excellent antibacterial activity.

  19. Exploration of Horizontal Intrinsic Spin Resonances in the AGS

    NASA Astrophysics Data System (ADS)

    Lin, Fanglei; Lee, S. Y.; Ahrens, Leif A.; Bai, Mei; Brown, Kevin; Courant, Ernest D.; Glenn, Joseph W.; Huang, Haixin; Luccio, Alfredo; Mackay, William W.; Ptitsyn, Vadim; Roser, Thomas; Tepikian, Steven; Tsoupas, Nicholaos; Wood, Jeff; Yip, Yin; Okamura, Masahiro; Takano, Junpei

    2006-04-01

    Siberian snakes have been employed to overcome spin resonances during polarized proton acceleration. Considering limited space in the AGS, strong partial snakes that rotate the spin by less than 180 degrees can be used to avoid the spin imperfection and intrinsic resonances in low energy accelerators. However, the tilt of spin away from the vertical direction may become sensitive to horizontal betatron motion which can also cause spin depolarization. These resonances, called horizontal intrinsic spin resonances, have been observed in simulations. Preliminary measurements with beam were also carried out in AGS 2005 polarized proton run. During the AGS 2006 run, we plan to explore the details about the horizontal intrinsics resonances further. This paper describes the experimental methods and the latest results.

  20. Accelerator system and method of accelerating particles

    NASA Technical Reports Server (NTRS)

    Wirz, Richard E. (Inventor)

    2010-01-01

    An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

  1. RHIC Sextant Test - Accelerator Systems and Performance

    NASA Astrophysics Data System (ADS)

    Pilat, F.; Ahrens, L.; Brown, K.; Connolly, R.; dell, G. F.; Fischer, W.; Kewisch, J.; Mackay, W.; Mane, V.; Peggs, S.; Satogata, T.; Tepikian, S.; Thompson, P.; Trbojevic, D.; Tsoupas, N.; Wei, J.

    1997-05-01

    One sextant of the RHIC collider and the full AtR (AGS to RHIC) transfer line have been commissioned in early 1997 with beam. We describe here the design and performance of the accelerator systems during the test, such as the magnet and power supply systems, instrumentation subsystems and application software. After reviewing the main milestones of the commissioning we describe a ramping test without beam that took place after the commissioning with beam. Finally, we analyze the implications of accelerator systems preformance and their impact on the plannig for RHIC installation and commissioning.

  2. Metal and elastomer seal tests for accelerator applications

    SciTech Connect

    Welch, K.M.; McIntyre, G.T.; Tuozzolo, J.E.; Skelton, R.; Pate, D.J.; Gill, S.M.

    1989-01-01

    The vacuum system of the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory has more than a thousand metal vacuum seals. Also, numerous elastomer seals are used throughout the AGS to seal large beam component chambers. An accelerator upgrade program is being implemented to reduce the AGS operating pressure by x100 and improve the reliability of the vacuum system. This paper describes work in progress on metal and elastomer vacuum seals to help meet those two objectives. Tests are reported on the sealing properties of a variety of metal seals used on different sealing surfaces. Results are also given on reversible sorption properties of certain elastomers. 16 refs., 6 figs., 4 tabs.

  3. 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.

  4. Mechanism and experimental study on the photocatalytic performance of Ag/AgCl @ chiral TiO2 nanofibers photocatalyst: the impact of wastewater components.

    PubMed

    Wang, Dawei; Li, Yi; Li Puma, Gianluca; Wang, Chao; Wang, Peifang; Zhang, Wenlong; Wang, Qing

    2015-03-21

    The effect of the water matrix components of a secondary effluent of a urban wastewater treatment plant on the photocatalytic activity of Ag/AgCl @ chiral TiO2 nanofibers and the undergoing reaction mechanisms were investigated. These effects were evaluated through the water components-induced changes on the net rate of hydroxyl radical (˙OH) generation and modeled using a relative rate technique. Dissolved organic matter DOM (k=-2.8×10(8) M(-1) s(-1)) scavenged reactive oxygen species, Cl(-) (k=-5.3×10(8) M(-1) s(-1)) accelerated the transformation from Ag to AgCl (which is not photocatalytically active under visible-light irradiation), while Ca(2+) at concentrations higher than 50 mM (k=-1.3×10(9) M(-1) s(-1)) induced aggregation of Ag/AgCl and thus all of them revealed inhibitory effects. In contrast, NO3(-) (k=6.9×10(8) M(-1) s(-1)) and CO3(2-) (k=3.7×10(8) M(-1) s(-1)) improved the photocatalytic activity of Ag/AgCl slightly by improving the rate of HO˙ generation. Other ubiquitous secondary effluent components including SO4(2-) (k=3.9×10(5) M(-1) s(-1)), NH3(+) (k=3.5×10(5) M(-1) s(-1)) and Na(+) (k=2.6×10(4) M(-1) s(-1)) had negligible effects. 90% of 17-α-ethynylestradiol (EE2) spiked in the secondary effluent was removed within 12 min, while the structure and size of Ag/AgCl @ chiral TiO2 nanofibers remained stable. This work may be helpful not only to uncover the photocatalytic mechanism of Ag/AgCl based photocatalyst but also to elucidate the transformation and transportation of Ag and AgCl in natural water.

  5. Miniature Swine for Preclinical Modeling of Complexities of Human Disease for Translational Scientific Discovery and Accelerated Development of Therapies and Medical Devices.

    PubMed

    Schomberg, Dominic T; Tellez, Armando; Meudt, Jennifer J; Brady, Dane A; Dillon, Krista N; Arowolo, Folagbayi K; Wicks, Joan; Rousselle, Serge D; Shanmuganayagam, Dhanansayan

    2016-04-01

    Noncommunicable diseases, including cardiovascular disease, diabetes, chronic respiratory disease, and cancer, are the leading cause of death in the world. The cost, both monetary and time, of developing therapies to prevent, treat, or manage these diseases has become unsustainable. A contributing factor is inefficient and ineffective preclinical research, in which the animal models utilized do not replicate the complex physiology that influences disease. An ideal preclinical animal model is one that responds similarly to intrinsic and extrinsic influences, providing high translatability and concordance of preclinical findings to humans. The overwhelming genetic, anatomical, physiological, and pathophysiological similarities to humans make miniature swine an ideal model for preclinical studies of human disease. Additionally, recent development of precision gene-editing tools for creation of novel genetic swine models allows the modeling of highly complex pathophysiology and comorbidities. As such, the utilization of swine models in early research allows for the evaluation of novel drug and technology efficacy while encouraging redesign and refinement before committing to clinical testing. This review highlights the appropriateness of the miniature swine for modeling complex physiologic systems, presenting it as a highly translational preclinical platform to validate efficacy and safety of therapies and devices.

  6. 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:

  7. Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning

    NASA Astrophysics Data System (ADS)

    Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

    2013-10-01

    An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

  8. Acceleration modules in linear induction accelerators

    NASA Astrophysics Data System (ADS)

    Wang, Shao-Heng; Deng, Jian-Jun

    2014-05-01

    The Linear Induction Accelerator (LIA) is a unique type of accelerator that is capable of accelerating kilo-Ampere charged particle current to tens of MeV energy. The present development of LIA in MHz bursting mode and the successful application into a synchrotron have broadened LIA's usage scope. Although the transformer model is widely used to explain the acceleration mechanism of LIAs, it is not appropriate to consider the induction electric field as the field which accelerates charged particles for many modern LIAs. We have examined the transition of the magnetic cores' functions during the LIA acceleration modules' evolution, distinguished transformer type and transmission line type LIA acceleration modules, and re-considered several related issues based on transmission line type LIA acceleration module. This clarified understanding should help in the further development and design of LIA acceleration modules.

  9. Reduction of Nitroarenes into Aryl Amines and N-Aryl hydroxylamines via Activation of NaBH4 and Ammonia-Borane Complexes by Ag/TiO2 Catalyst

    PubMed Central

    Andreou, Dimitrios; Iordanidou, Domna; Tamiolakis, Ioannis; Armatas, Gerasimos S.; Lykakis, Ioannis N.

    2016-01-01

    In this study, we report the fabrication of mesoporous assemblies of silver and TiO2 nanoparticles (Ag/MTA) and demonstrate their catalytic efficiency for the selective reduction of nitroarenes. The Ag/TiO2 assemblies, which show large surface areas (119–128 m2·g−1) and narrow-sized mesopores (ca. 7.1–7.4 nm), perform as highly active catalysts for the reduction of nitroarenes, giving the corresponding aryl amines and N-aryl hydroxylamines with NaBH4 and ammonia-borane (NH3BH3), respectively, in moderate to high yields, even in large scale reactions (up to 5 mmol). Kinetic studies indicate that nitroarenes substituted with electron-withdrawing groups reduced faster than those with electron-donating groups. The measured positive ρ values from the formal Hammett-type kinetic analysis of X-substituted nitroarenes are consistent with the proposed mechanism that include the formation of possible [Ag]-H hybrid species, which are responsible for the reduction process. Because of the high observed chemo selectivities and the clean reaction processes, the present catalytic systems, i.e., Ag/MTA-NaBH4 and Ag/MTA-NH3BH3, show promise for the efficient synthesis of aryl amines and N-aryl hydroxylamines at industrial levels. PMID:28344310

  10. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1995-01-01

    The application of electric propulsion to communications satellites, however, has been limited to the use of hydrazine thrusters with electric heaters for thrust and specific impulse augmentation. These electrothermal thrusters operate at specific impulse levels of approximately 300 s with heater powers of about 500 W. Low power arcjets (1-3 kW) are currently being investigated as a way to increase specific impulse levels to approximately 500 s. Ion propulsion systems can easily produce specific impulses of 3000 s or greater, but have yet to be applied to communications satellites. The reasons most often given for not using ion propulsion systems are their high level of overall complexity, low thrust with long burn times, and the difficulty of integrating the propulsion system into existing commercial spacecraft busses. The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass.

  11. A comparative study about electronic structures at rubrene/Ag and Ag/rubrene interfaces

    SciTech Connect

    Sinha, Sumona Mukherjee, M.

    2015-10-15

    The contact between the electrode and the organic semiconductor is one of the most crucial factors in determining the organic device performance. The development and production technology of different organic devices require the understanding of different types of metal/organic semiconducting thin film interfaces. Comparisons about the electronic structures at Rubrene/Ag and Ag/Rubrene interfaces have been studied using photoemission spectroscopy. The Ag on rubrene interfaces is found to show more interesting and complex natures than its counterpart. The vacuum level (VL) was shifted about 0.51 eV from push back effect for deposition of 5 Å rubrene onto Ag film whereas the electronic features of silver was only suppressed and no energy shift was resulted. While the deposition of 5 Å Ag onto rubrene film leads to the diffusion of the Ag atoms, as a cluster with quantum size effect, inside the film. Angle dependent XPS measurement indicates that diffused metal clusters were present at entire probed depth of the film. Moreover these clusters dope the uppermost surface of the rubrene film which consequences a shift of the electronic states of thick organic film towards higher binding energy. The VL was found to shift about 0.31 eV toward higher binding energy whereas the shift was around 0.21 eV for the electronic states of rubrene layer.

  12. Progress on plasma accelerators

    SciTech Connect

    Chen, P.

    1986-05-01

    Several plasma accelerator concepts are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA) and the Plasma Wake Field Accelerator (PWFA). Various accelerator physics issues regarding these schemes are discussed, and numerical examples on laboratory scale experiments are given. The efficiency of plasma accelerators is then revealed with suggestions on improvements. Sources that cause emittance growth are discussed briefly.

  13. Rare Kaon Decays, KEK experiment E391 and E14 at the Japan Physics and Accelerator Research Complex (J-PARC)

    SciTech Connect

    Wah, Yau Wai

    2012-12-06

    The goal of the J-PARC neutral kaon experiment (E14/KOTO) is to discover and measure the rate of the kaon rare decay to pi-zero and two neutrinos. This flavor changing neutral current decay proceeds through second-order weak interactions. Other, as yet undiscovered particles, which can mediate the decay could provide an enhancement (or depletion) to the branching ratio which in the Standard Model is accurately predicted within a few percent to be 2.8x10-11. The experiment is designed to observe more than 100 events at the Standard Model branching. It is a follow-up of the KEK E391a experiment and has stage-2 approval by J-PARC PAC in 2007. E14/KOTO has collaborators from Japan (Kyoto, Osaka, Yamagata, Saga), US (Arizona State, Chicago, Michigan Ann Arbor), Taiwan (National Taiwan), Korea, and Russia (Dubna). The experiment exploits the 300kW 30-50 GeV proton delivery of the J-PARC accelerator with a hermetic high acceptance detector with a fine grained Cesium Iodide (CsI) crystal calorimeter, and state of the art electronic front end and data acquisition system. With the recovery of the tsunami disaster on March 11th 2011, E14 is scheduled to start collecting data in December 2012. During the detector construction phase, Chicago focuses on the front end electronics readout of the entire detector system, particularly the CsI calorimeter. The CsI crystals together with its photomultipliers were previously used at the Fermilab KTeV experiment (E832/E799), and were loaned to E14 via this Chicago DOE support. The new readout electronics includes an innovative 10-pole pulse-shaping technique coupled with high speed digitization (14-bit 125MHz and 12-bit 500MHz). This new instrument enables us to measure both energy and timing, particularly with timing resolution better than 100 psec. Besides the cost saving by elimination of the standard time to digital converters, it is now possible to measure the momenta of the final state photons for additional background suppression

  14. ESS Accelerator Cryoplant Process Design

    NASA Astrophysics Data System (ADS)

    Wang, X. L.; Arnold, P.; Hees, W.; Hildenbeutel, J.; Weisend, J. G., II

    2015-12-01

    The European Spallation Source (ESS) is a neutron-scattering facility being built with extensive international collaboration in Lund, Sweden. The ESS accelerator will deliver protons with 5 MW of power to the target at 2.0 GeV, with a nominal current of 62.5 mA. The superconducting part of the accelerator is about 300 meters long and contains 43 cryomodules. The ESS accelerator cryoplant (ACCP) will provide the cooling for the cryomodules and the cryogenic distribution system that delivers the helium to the cryomodules. The ACCP will cover three cryogenic circuits: Bath cooling for the cavities at 2 K, the thermal shields at around 40 K and the power couplers thermalisation with 4.5 K forced helium cooling. The open competitive bid for the ACCP took place in 2014 with Linde Kryotechnik AG being selected as the vendor. This paper summarizes the progress in the ACCP development and engineering. Current status including final cooling requirements, preliminary process design, system configuration, machine concept and layout, main parameters and features, solution for the acceptance tests, exergy analysis and efficiency is presented.

  15. Complex Chromosomal Rearrangements Induced in Vivo by Heavy Ions

    NASA Technical Reports Server (NTRS)

    Durante, M.; Ando, K.; Furusawa, G.; Obe, G.; George, K.; Cucinotta, F. A.

    2004-01-01

    It has been suggested that the ratio complex/simple exchanges can be used as a biomarker of exposure to high-LET radiation. We tested this hypothesis in vivo, by considering data from several studies that measured complex exchanges in peripheral blood from humans exposed to mixed fields of low- and high-LET radiation. In particular, we studied data from astronauts involved in long-term missions in low-Earth-orbit, and uterus cancer patients treated with accelerated carbon ions. Data from two studies of chromosomal aberrations in astronauts used blood samples obtained before and after space flight, and a third study used blood samples from patients before and after radiotherapy course. Similar methods were used in each study, where lymphocytes were stimulated to grow in vitro, and collected after incubation in either colcemid or calyculin A. Slides were painted with whole-chromosome DNA fluorescent probes (FISH), and complex and simple chromosome exchanges in the painted genome were classified separately. Complex-type exchanges were observed at low frequencies in control subjects, and in our test subjects before the treatment. No statistically significant increase in the yield of complex-type exchanges was induced by the space flight. Radiation therapy induced a high fraction of complex exchanges, but no significant differences could be detected between patients treated with accelerated carbon ions or X-rays. Complex chromosomal rearrangements do not represent a practical biomarker of radiation quality in our test subjects. Copyright 2003 S. Karger AG, Basel.

  16. Accelerators for Intensity Frontier Research

    SciTech Connect

    Derwent, Paul; /Fermilab

    2012-05-11

    In 2008, the Particle Physics Project Prioritization Panel identified three frontiers for research in high energy physics, the Energy Frontier, the Intensity Frontier, and the Cosmic Frontier. In this paper, I will describe how Fermilab is configuring and upgrading the accelerator complex, prior to the development of Project X, in support of the Intensity Frontier.

  17. 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).

  18. Effects of Ag addition on FePt L1{sub 0} ordering transition: A direct observation of ordering transition and Ag segregation in FePtAg alloy films

    SciTech Connect

    Wang, Lei; Yu, Youxing; Gao, Tenghua

    2015-12-21

    FePt and (FePt){sub 91.2}Ag{sub 8.8} alloy films were deposited by magnetron sputtering. The average coercivity of (FePt){sub 91.2}Ag{sub 8.8} films reaches 8.51 × 10{sup 5} A/m, which is 0.63 × 10{sup 5} A/m higher than that of the corresponding FePt films. Ag addition effectively promotes the FePt L1{sub 0} ordering transition at a relatively low annealing temperature of 400 °C. The promotion mechanism was investigated by using in situ high-resolution transmission electron microscopy (HRTEM) and ex situ X-ray absorption fine structure (XAFS). The concurrence of ordering transition and Ag segregation in FePtAg alloy films was first observed by using in situ heating HRTEM. The time-resolved evolution reveals more details on the role of Ag addition in FePt low-temperature ordering. Ex situ XAFS results further confirm that Ag replaces Fe sites in the as-deposited films and segregates from FePt-Ag solid solution phase through annealing at elevated temperatures. The segregation of Ag atoms leaves vacancies in the grain. The vacancy formation is believed to accelerate the diffusion of Fe and Pt atoms, which is critical for the L1{sub 0} ordering transition.

  19. 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

  20. X-ray diffraction structure of the 1,1{prime}-bis(diphenylphosphino)ferrocene (dppf)-bridged complex [(dppf)AgCl]{sub 2}: An unexpected product from the reaction between cis-(bpy){sub 2}RuCl{sub 2} and dppf in the presence of AgBF{sub 4}

    SciTech Connect

    Yang, K.; Bott, S.G.; Richmond, M.G.

    1995-05-01

    The reaction between cis-Ru(bpy){sub 2}Cl{sub 2}(where bpy = bipyridine) and the diphosphine ligand 1,1 {prime} - bis(diphenylphosphino)ferrocene (dppf) in the presence of AgBF{sub 4} has led to the isolation of the title compound [Ag(dppf)Cl]{sub 2}. [Ag(dppf)Cl]{sub 2} has been structurally characterized by X-ray diffraction analysis, which confirms the bridging mode adopted by the ancillary dppf ligand and the centrosymmetric nature of this molecule. Dimeric [Ag(dppf)Cl]{sub 2} crystallizes in the triclinic space group P1, a = 11.426(1) {angstrom}, b = 11.509(1) {angstrom}, c = 12.786(1) {angstrom}, {alpha} = 68.96(2){degrees}, {beta} = 70.66(2){degrees} = {gamma} = 71.24(2){degrees}, V = 1441(1) {angstrom}{sup 3}, Z = 1, d{sub calc} = 1.608 g {center_dot} cm{sup {minus}3}; R = 0.0445, R{sub 2} = 0.0566 for 4486 observed reflections with l {ge} 3{sigma}(l).

  1. Quantification of HBsAg: basic virology for clinical practice.

    PubMed

    Lee, Jung Min; Ahn, Sang Hoon

    2011-01-21

    Hepatitis B surface antigen (HBsAg) is produced and secreted through a complex mechanism that is still not fully understood. In clinical fields, HBsAg has long served as a qualitative diagnostic marker for hepatitis B virus infection. Notably, advances have been made in the development of quantitative HBsAg assays, which have allowed viral replication monitoring, and there is an opportunity to make maximal use of quantitative HBsAg to elucidate its role in clinical fields. Yet, it needs to be underscored that a further understanding of HBsAg, not only from clinical point of view but also from a virologic point of view, would enable us to deepen our insights, so that we could more widely expand and apply its utility. It is also important to be familiar with HBsAg variants and their clinical consequences in terms of immune escape mutants, issues resulting from overlap with corresponding mutation in the P gene, and detection problems for the HBsAg variants. In this article, we review current concepts and issues on the quantification of HBsAg titers with respect to their biologic nature, method principles, and clinically relevant topics.

  2. Measurement of Coriolis Acceleration with a Smartphone

    ERIC Educational Resources Information Center

    Shaku, Asif; Kraft, Jakob

    2016-01-01

    Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern…

  3. Fighting the Residual Polarization Loss in the AGS

    SciTech Connect

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

    2009-08-04

    A dual partial snake scheme has been used for AGS polarized proton operation for several years. It has provided polarized proton beams with 1.5x10{sup 11} protons per bunch and 65% polarization for the RHIC spin program. There is still residual polarization loss due to both snake resonances and horizontal resonances as shown in the data. Several schemes were tested or proposed in the AGS to mitigate the loss, such as putting horizontal tune into the spin tune gap, injection into a accelerating bucket, and tune jump across the horizontal resonances. This paper presents the experiment and simulation results and analyses.

  4. SETUP AND PERFORMANCE OF THE RHIC INJECTOR ACCELERATORS FOR THE 2007 RUN WITH GOLD IONS

    SciTech Connect

    GARDNER,C.; AHRENS, L.; ALESSI, J.; BENJAMIN, J.; BLASKIEWICZ, M.; ET AL.

    2007-06-25

    Gold ions for the 2007 run of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) are accelerated in the Tandem, Booster and AGS prior to injection into RHIC. The setup and performance of this chain of accelerators is reviewed with a focus on improvements in the quality of beam delivered to RHIC. In particular, more uniform stripping foils between Booster and AGS7 and a new bunch merging scheme in AGS have provided beam bunches with reduced longitudinal emittance for RHIC.

  5. RELATIVISTIC HEAVY ION PHYSICS : RESULTS FROM AGS TO RHIC.

    SciTech Connect

    STEINBERG,P.

    2002-06-20

    High-energy collisions of heavy ions provide a means to study QCD in a regime of high parton density, and may provide insight into its phme structure. Results from the four experiments at RHIC (BRAHMS, PHENIX, PHOBOS and STAR) are presented, and placed in context with the lower energy data from the AGS and SPS accelerators. The focus is on the insights these measurements provide into the time history of the collision process. Taken together, the data point to the creation of a deconfined state of matter that forms quickly, expands rapidly and freezes out suddenly. With the new RHIC data, systematic data now exists for heavy ion collisions as a function of {radical}s over several orders of magnitude and as a function of impact parameter. These data test the interplay between hard and soft processes in a large-volume system where nucleons are struck multiple times. The data is consistent with creating a deconfined state (jet quenching) that forms quickly (saturation models), expands rapidly (radial and elliptic flow) and freezes out suddenly (single freezeout and blast wave fits). There are also intriguing connections with particle production in elementary systems, which point to the role of the energy available for particle production on the features of the final state. Many in this field are optimistic that the careful understanding of this experimental data may lead t o the theoretical breakthroughs that will connect these complex systems to the fundamental lattice predict ions.

  6. Muon Acceleration-RLA and FFAG

    SciTech Connect

    Bogacz, S. Alex

    2011-10-06

    Various acceleration schemes for muons are presented. The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and 'beam shaping' can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a non-scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain across the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. The RLAs offer very efficient usage of high gradient superconducting RF and ability to adjust path-length after each linac pass through individual return arcs with uniformly periodic FODO optics suitable for chromatic compensation of emittace dilution with sextupoles. However, they require spreaders/recombiners switchyards at both linac ends and significant total length of the arcs. The non-scaling Fixed Field Alternating Gradient (FFAG) ring combines compactness with very large chromatic acceptance (twice the injection energy) and it allows for large number of passes through the RF (at least eight, possibly as high as 15).

  7. Bio-nano complexes of ZVFeNPs/Fe-s-M13 and Cd (II)/Cd-s-M13 accelerate Cd (II) reduction by FeNPs through dual dispersing and separate deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Nakano, Kazuhiko; Yu, Huimin; Shen, Zhongyao

    2014-03-01

    Reduction of Cd (II) in liquor by solid zero valent Fe nanoparticles (ZVFeNPs) is a liquid-solid biphasic reaction in which the reduction efficiency was often lowered by either aggregation of ZVFeNPs or coating of the generated ZVCd. In light of the filamentous nanostructure of bacteriophage M13 with ˜2700 copies of pVIII protein in delicate distribution at the coat, a novel dual dispersing reduction route was designed by introducing two different kinds of M13 with Fe-binding specificity (Fe-s-M13) and Cd-binding specificity (Cd-s-M13) to disperse ZVFeNPs and Cd (II) ions, respectively. The Fe-s-M13 was used for synthesis of the ZVFeNPs/Fe-s-M13 complex, where ZVFeNPs were uniformly dispersed into small nanoparticles (5-10 nm) on Fe-s-M13. The engineered Cd-s-M13, constructed by genetic recombination of pVIII through inserting the gene of a biopanned 7-mer Cd-specific peptide (SCPICPG) into the N-terminus of pVIII gene, was used for Cd (II) dispersion before reduction. The dispersed complex of Cd(II)/Cd-s-M13 was rapidly reduced by complex of ZVFeNPs/Fe-s-M13. Kinetics results showed that the initial reduction rate and final reduction ratio of Cd (II) increased by 35.7% and 16.4%, respectively, through dispersion of ZVFeNPs by Fe-s-M13; they improved again by 53.6% and 37.0%, respectively, through further dispersion of Cd (II) by Cd-s-M13. TEM and EDS results revealed that the acceleration effect of the dual dispersing reduction was arising from uniform dispersion of the small ZVFeNPs and separate deposition of the reduced ZVCd on the two different M13 phages.

  8. Visible-light photoactivity of plasmonic silver supported on mesoporous TiO2 nanoparticles (Ag-MTN) for enhanced degradation of 2-chlorophenol: Limitation of Ag-Ti interaction

    NASA Astrophysics Data System (ADS)

    Jaafar, N. F.; Jalil, A. A.; Triwahyono, S.

    2017-01-01

    Various weight loadings of Ag (1-10 wt.%) were introduced to mesoporous titania nanoparticles (MTN) via a direct in-situ electrochemical method. The catalysts were characterized by XRD, surface area analysis, FTIR, ESR, FESEM-EDX and TEM. Characterization results indicated that the introduction of Ag onto MTN decreased the particles size and band gap of the MTN while increasing the number of oxygen vacancies (OV) and Ti3+ site defects (TSD). The activity performance of Ag-MTN on photodegradation of 2-chlorophenol (2-CP) under visible light irradiation was in the following order: 5 wt% Ag-MTN> 1 wt% Ag-MTN > MTN > 10 wt% Ag-MTN, with degradation percentages of 97, 88, 80 and 63%, respectively. The synergistic effect between Ag0 and MTN seemed to play an important role in the system. The Ag0 acted as both an electron trap and a plasmonic sensitizer which suppressed the electron-hole recombination, while OV and TSD in the MTN accelerated the production of hydroxyl radicals for enhanced degradation of 2-CP. However, the formation of Ti-O-Ag in 10 wt% Ag-MTN was found to decrease the photoactivity due to the decrease in the formation of Ag0, TSD and OV as well as the increase in band gap energy. The photodegradation of 5 wt% Ag-MTN followed a pseudo-first-order Langmuir- Hinshelwood model and the catalyst was still stable after five cycles.

  9. Community Petascale Project for Accelerator Science and Simulation: Advancing Computational Science for Future Accelerators and Accelerator Technologies

    SciTech Connect

    Spentzouris, P.; Cary, J.; McInnes, L.C.; Mori, W.; Ng, C.; Ng, E.; Ryne, R.; /LBL, Berkeley

    2011-11-14

    The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors. ComPASS is in the first year of executing its plan to develop the next-generation HPC accelerator modeling tools. ComPASS aims to develop an integrated simulation environment that will utilize existing and new accelerator physics modules with petascale capabilities, by employing modern computing and solver technologies. The ComPASS vision is to deliver to accelerator scientists a virtual accelerator and virtual prototyping modeling environment, with the necessary multiphysics, multiscale capabilities. The plan for this development includes delivering accelerator modeling applications appropriate for each stage of the ComPASS software evolution. Such applications are already being used to address challenging problems in accelerator design and optimization. The ComPASS organization

  10. Preparation and Characterization of the Argentates: Ag?P(CF3)2!2(-), Ag?(mu-P(CF3)2)M(CO)5!2(-) (M = Cr, W) and Ag?mu-P(C6F5)2)W(CO)5!2(-): X-Ray Crystal Structure of K(18-Crown-6)Ag?mu-P(CF3)2)Cr(CO)5!2

    DTIC Science & Technology

    2006-05-31

    The novel bis?bis(trifluoromethyl)phosphanido ! argentate , Ag(P(CF3)2!2(-), is obtained via the reaction of HP(CF3)2 with Ag(CN)2(-) and isolated as...complexes M(CO)5PH(CF3)2 (M= Cr, W) with K(18- crown-6)Ag(CN)2 the formation of the comparable trinuclear argentates , Ag?(mu P(CF3)2)M(CO)5!2(-) is

  11. Future accelerator technology

    SciTech Connect

    Sessler, A.M.

    1986-05-01

    A general discussion is presented of the acceleration of particles. Upon this foundation is built a categorization scheme into which all accelerators can be placed. Special attention is devoted to accelerators which employ a wake-field mechanism and a restricting theorem is examined. It is shown how the theorem may be circumvented. Comments are made on various acceleration schemes.

  12. ACCELERATION AND THE GIFTED.

    ERIC Educational Resources Information Center

    GIBSON, ARTHUR R.; STEPHANS, THOMAS M.

    ACCELERATION OF PUPILS AND SUBJECTS IS CONSIDERED A MEANS OF EDUCATING THE ACADEMICALLY GIFTED STUDENT. FIVE INTRODUCTORY ARTICLES PROVIDE A FRAMEWORK FOR THINKING ABOUT ACCELERATION. FIVE PROJECT REPORTS OF ACCELERATED PROGRAMS IN OHIO ARE INCLUDED. ACCELERATION IS NOW BEING REGARDED MORE FAVORABLY THAN FORMERLY, BECAUSE METHODS HAVE BEEN…

  13. Laser driven ion accelerator

    DOEpatents

    Tajima, Toshiki

    2005-06-14

    A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

  14. Laser driven ion accelerator

    DOEpatents

    Tajima, Toshiki

    2006-04-18

    A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

  15. Contribution of Eu ions on the precipitation of silver nanoparticles in Ag-Eu co-doped borate glasses

    SciTech Connect

    Jiao, Qing; Qiu, Jianbei; Zhou, Dacheng; Xu, Xuhui

    2014-03-01

    Graphical abstract: - Highlights: • Silver nanoparticles are precipitated from the borate glasses during the melting process without any further heat treatment. • The reduction of Eu{sup 3+} ions to Eu{sup 2+} ions is presented in this material. • The intensity of Ag{sup +} luminescence. • The introduction of Eu ions accelerated the reaction between Eu{sup 2+} ions and silver ions inducing the silver clusters formation. - Abstract: Ag{sup +} doped sodium borate glasses with different Eu ions concentration were prepared by the melt-quenching method. The absorption at about 410 nm which was caused by the surface plasmon resonance (SPR) of Ag nanoparticles (NPs) is promoted with increasing of Eu ions concentration. Meanwhile, the luminescent spectra showed that the emission intensity of Ag{sup +} decreased while that of the Ag aggregates increased simultaneously. The results indicated that the Ag ions intend to form the high-polymeric state such as Ag aggregates and nanoparticles with increasing of europium ions. Owing to the self-reduction of Eu{sup 3+} to Eu{sup 2+} in our glass system, it revealed that Ag{sup +} has been reduced by the neighboring Eu{sup 2+} which leads to the formation of Ag aggregates and the precipitation of Ag NPs in the matrix. In addition, energy transfer (ET) process from Ag{sup +}/Ag aggregates to the Eu{sup 3+} was investigated for the enhancement of Eu{sup 3+} luminescence.

  16. APT accelerator. Topical report

    SciTech Connect

    Lawrence, G.; Rusthoi, D.

    1995-03-01

    The Accelerator Production of Tritium (APT) project, sponsored by Department of Energy Defense Programs (DOE/DP), involves the preconceptual design of an accelerator system to produce tritium for the nation`s stockpile of nuclear weapons. Tritium is an isotope of hydrogen used in nuclear weapons, and must be replenished because of radioactive decay (its half-life is approximately 12 years). Because the annual production requirements for tritium has greatly decreased since the end of the Cold War, an alternative approach to reactors for tritium production, based on a linear accelerator, is now being seriously considered. The annual tritium requirement at the time this study was undertaken (1992-1993) was 3/8 that of the 1988 goal, usually stated as 3/8-Goal. Continued reduction in the number of weapons in the stockpile has led to a revised (lower) production requirement today (March, 1995). The production requirement needed to maintain the reduced stockpile, as stated in the recent Nuclear Posture Review (summer 1994) is approximately 3/16-Goal, half the previous level. The Nuclear Posture Review also requires that the production plant be designed to accomodate a production increase (surge) to 3/8-Goal capability within five years, to allow recovery from a possible extended outage of the tritium plant. A multi-laboratory team, collaborating with several industrial partners, has developed a preconceptual APT design for the 3/8-Goal, operating at 75% capacity. The team has presented APT as a promising alternative to the reactor concepts proposed for Complex-21. Given the requirements of a reduced weapons stockpile, APT offers both significant safety, environmental, and production-fexibility advantages in comparison with reactor systems, and the prospect of successful development in time to meet the US defense requirements of the 21st Century.

  17. SETUP AND PERFORMANCE OF THE RHIC INJECTOR ACCELERATORS FOR THE 2005 RUN WITH COPPER IONS.

    SciTech Connect

    AHRENS, L.; ALESSI, J.; GARDNER, C.J.

    2005-05-16

    Copper ions for the 2005 run [1] of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) are accelerated in the Tandem, Booster and AGS prior to injection into RHIC. The setup and performance of these accelerators with copper are reviewed in this paper.

  18. The Spallation Neutron Source accelerator system design

    NASA Astrophysics Data System (ADS)

    Henderson, S.; Abraham, W.; Aleksandrov, A.; Allen, C.; Alonso, J.; Anderson, D.; Arenius, D.; Arthur, T.; Assadi, S.; Ayers, J.; Bach, P.; Badea, V.; Battle, R.; Beebe-Wang, J.; Bergmann, B.; Bernardin, J.; Bhatia, T.; Billen, J.; Birke, T.; Bjorklund, E.; Blaskiewicz, M.; Blind, B.; Blokland, W.; Bookwalter, V.; Borovina, D.; Bowling, S.; Bradley, J.; Brantley, C.; Brennan, J.; Brodowski, J.; Brown, S.; Brown, R.; Bruce, D.; Bultman, N.; Cameron, P.; Campisi, I.; Casagrande, F.; Catalan-Lasheras, N.; Champion, M.; Champion, M.; Chen, Z.; Cheng, D.; Cho, Y.; Christensen, K.; Chu, C.; Cleaves, J.; Connolly, R.; Cote, T.; Cousineau, S.; Crandall, K.; Creel, J.; Crofford, M.; Cull, P.; Cutler, R.; Dabney, R.; Dalesio, L.; Daly, E.; Damm, R.; Danilov, V.; Davino, D.; Davis, K.; Dawson, C.; Day, L.; Deibele, C.; Delayen, J.; DeLong, J.; Demello, A.; DeVan, W.; Digennaro, R.; Dixon, K.; Dodson, G.; Doleans, M.; Doolittle, L.; Doss, J.; Drury, M.; Elliot, T.; Ellis, S.; Error, J.; Fazekas, J.; Fedotov, A.; Feng, P.; Fischer, J.; Fox, W.; Fuja, R.; Funk, W.; Galambos, J.; Ganni, V.; Garnett, R.; Geng, X.; Gentzlinger, R.; Giannella, M.; Gibson, P.; Gillis, R.; Gioia, J.; Gordon, J.; Gough, R.; Greer, J.; Gregory, W.; Gribble, R.; Grice, W.; Gurd, D.; Gurd, P.; Guthrie, A.; Hahn, H.; Hardek, T.; Hardekopf, R.; Harrison, J.; Hatfield, D.; He, P.; Hechler, M.; Heistermann, F.; Helus, S.; Hiatt, T.; Hicks, S.; Hill, J.; Hill, J.; Hoff, L.; Hoff, M.; Hogan, J.; Holding, M.; Holik, P.; Holmes, J.; Holtkamp, N.; Hovater, C.; Howell, M.; Hseuh, H.; Huhn, A.; Hunter, T.; Ilg, T.; Jackson, J.; Jain, A.; Jason, A.; Jeon, D.; Johnson, G.; Jones, A.; Joseph, S.; Justice, A.; Kang, Y.; Kasemir, K.; Keller, R.; Kersevan, R.; Kerstiens, D.; Kesselman, M.; Kim, S.; Kneisel, P.; Kravchuk, L.; Kuneli, T.; Kurennoy, S.; Kustom, R.; Kwon, S.; Ladd, P.; Lambiase, R.; Lee, Y. Y.; Leitner, M.; Leung, K.-N.; Lewis, S.; Liaw, C.; Lionberger, C.; Lo, C. C.; Long, C.; Ludewig, H.; Ludvig, J.; Luft, P.; Lynch, M.; Ma, H.; MacGill, R.; Macha, K.; Madre, B.; Mahler, G.; Mahoney, K.; Maines, J.; Mammosser, J.; Mann, T.; Marneris, I.; Marroquin, P.; Martineau, R.; Matsumoto, K.; McCarthy, M.; McChesney, C.; McGahern, W.; McGehee, P.; Meng, W.; Merz, B.; Meyer, R.; Meyer, R.; Miller, B.; Mitchell, R.; Mize, J.; Monroy, M.; Munro, J.; Murdoch, G.; Musson, J.; Nath, S.; Nelson, R.; Nelson, R.; O`Hara, J.; Olsen, D.; Oren, W.; Oshatz, D.; Owens, T.; Pai, C.; Papaphilippou, I.; Patterson, N.; Patterson, J.; Pearson, C.; Pelaia, T.; Pieck, M.; Piller, C.; Plawski, T.; Plum, M.; Pogge, J.; Power, J.; Powers, T.; Preble, J.; Prokop, M.; Pruyn, J.; Purcell, D.; Rank, J.; Raparia, D.; Ratti, A.; Reass, W.; Reece, K.; Rees, D.; Regan, A.; Regis, M.; Reijonen, J.; Rej, D.; Richards, D.; Richied, D.; Rode, C.; Rodriguez, W.; Rodriguez, M.; Rohlev, A.; Rose, C.; Roseberry, T.; Rowton, L.; Roybal, W.; Rust, K.; Salazer, G.; Sandberg, J.; Saunders, J.; Schenkel, T.; Schneider, W.; Schrage, D.; Schubert, J.; Severino, F.; Shafer, R.; Shea, T.; Shishlo, A.; Shoaee, H.; Sibley, C.; Sims, J.; Smee, S.; Smith, J.; Smith, K.; Spitz, R.; Staples, J.; Stein, P.; Stettler, M.; Stirbet, M.; Stockli, M.; Stone, W.; Stout, D.; Stovall, J.; Strelo, W.; Strong, H.; Sundelin, R.; Syversrud, D.; Szajbler, M.; Takeda, H.; Tallerico, P.; Tang, J.; Tanke, E.; Tepikian, S.; Thomae, R.; Thompson, D.; Thomson, D.; Thuot, M.; Treml, C.; Tsoupas, N.; Tuozzolo, J.; Tuzel, W.; Vassioutchenko, A.; Virostek, S.; Wallig, J.; Wanderer, P.; Wang, Y.; Wang, J. G.; Wangler, T.; Warren, D.; Wei, J.; Weiss, D.; Welton, R.; Weng, J.; Weng, W.-T.; Wezensky, M.; White, M.; Whitlatch, T.; Williams, D.; Williams, E.; Wilson, K.; Wiseman, M.; Wood, R.; Wright, P.; Wu, A.; Ybarrolaza, N.; Young, K.; Young, L.; Yourd, R.; Zachoszcz, A.; Zaltsman, A.; Zhang, S.; Zhang, W.; Zhang, Y.; Zhukov, A.

    2014-11-01

    The Spallation Neutron Source (SNS) was designed and constructed by a collaboration of six U.S. Department of Energy national laboratories. The SNS accelerator system consists of a 1 GeV linear accelerator and an accumulator ring providing 1.4 MW of proton beam power in microsecond-long beam pulses to a liquid mercury target for neutron production. The accelerator complex consists of a front-end negative hydrogen-ion injector system, an 87 MeV drift tube linear accelerator, a 186 MeV side-coupled linear accelerator, a 1 GeV superconducting linear accelerator, a 248-m circumference accumulator ring and associated beam transport lines. The accelerator complex is supported by ~100 high-power RF power systems, a 2 K cryogenic plant, ~400 DC and pulsed power supply systems, ~400 beam diagnostic devices and a distributed control system handling ~100,000 I/O signals. The beam dynamics design of the SNS accelerator is presented, as is the engineering design of the major accelerator subsystems.

  19. Accelerator science in medical physics.

    PubMed

    Peach, K; Wilson, P; Jones, B

    2011-12-01

    The use of cyclotrons and synchrotrons to accelerate charged particles in hospital settings for the purpose of cancer therapy is increasing. Consequently, there is a growing demand from medical physicists, radiographers, physicians and oncologists for articles that explain the basic physical concepts of these technologies. There are unique advantages and disadvantages to all methods of acceleration. Several promising alternative methods of accelerating particles also have to be considered since they will become increasingly available with time; however, there are still many technical problems with these that require solving. This article serves as an introduction to this complex area of physics, and will be of benefit to those engaged in cancer therapy, or who intend to acquire such technologies in the future.

  20. Accelerator science in medical physics

    PubMed Central

    Peach, K; Wilson, P; Jones, B

    2011-01-01

    The use of cyclotrons and synchrotrons to accelerate charged particles in hospital settings for the purpose of cancer therapy is increasing. Consequently, there is a growing demand from medical physicists, radiographers, physicians and oncologists for articles that explain the basic physical concepts of these technologies. There are unique advantages and disadvantages to all methods of acceleration. Several promising alternative methods of accelerating particles also have to be considered since they will become increasingly available with time; however, there are still many technical problems with these that require solving. This article serves as an introduction to this complex area of physics, and will be of benefit to those engaged in cancer therapy, or who intend to acquire such technologies in the future. PMID:22374548

  1. 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.

  2. 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.

  3. Pros and Cons of the Acceleration Scheme (NF-IDS)

    SciTech Connect

    Bogacz, Alex; Bogacz, Slawomir

    2008-07-01

    The overall goal of the acceleration systems: large acceptance acceleration to 25 GeV and beam shaping can be accomplished by various fixed field accelerators at different stages. They involve three superconducting linacs: a single pass linear Pre-accelerator followed by a pair of multi-pass Recirculating Linear Accelerators (RLA) and finally a nonâ scaling FFAG ring. The present baseline acceleration scenario has been optimized to take maximum advantage of appropriate acceleration scheme at a given stage. Pros and cons of various stages are discussed here in detail. The solenoid based Pre-accelerator offers very large acceptance and facilitates correction of energy gain across the bunch and significant longitudinal compression trough induced synchrotron motion. However, far off-crest acceleration reduces the effective acceleration gradient and adds complexity through the requirement of individual RF phase control for each cavity. Close proximity of strong solenoids and superc

  4. Simulations on the AGS horizontal tune jump mechanism

    SciTech Connect

    Lin,F.; Huang, H.; Luccio, A. U.; Roser, T.

    2009-05-04

    A new horizontal tune jump mechanism has been proposed to overcome the horizontal intrinsic resonances and preserve the polarization of the proton beam in the Alternating Gradient Synchrotron (AGS) during the energy ramp. An adiabatic change of the AGS lattice is needed to avoid the emittance growth in both horizontal and vertical planes, as the emittance growth can deteriorate the polarization of the proton beam. Two critical questions are necessary to be answered: how fast can the lattice be changed and how much emittance growth can be tolerated from both optics and polarization points of view? Preliminary simulations, using a realistic AGS lattice and acceleration rate, have been carried out to give a first glance of this mechanism. Results with different optics are presented in this paper.

  5. The effect of triphenylphosphane on corrosion inhibition of benzotriazole at Ag electrode monitored by SERS in nonaqueous solution.

    PubMed

    Yuan, Ya-Xian; Yang, Feng-Zhu; Morag, Clark-Heptinstall; Liu, Dong; Zhang, Yong; Gu, Ren-Ao; Yao, Jian-Lin

    2013-03-15

    The corrosion inhibition behavior of benzotriazole (BTAH) on Ag electrodes and the influence of triphenylphosphane (pph(3)) were investigated by electrochemical method, in situ surface-enhanced Raman spectroscopy (SERS) and direct electrochemical synthesis of surface complexes in nonaqueous solution. The results indicated that the BTA(-) ion was coordinated to the Ag surface to form a highly cross-linked surface polymer complex of [Ag(BTA)](n), which suppressed the dissolution and oxidation of Ag effectively. The introduction of a neutral ligand of pph(3) blocked the surface coordination processes of BTAH with the Ag electrode. It resulted in a decrease of inhibition efficiency to Ag surface. The ligand of pph(3) played a negative role on the corrosion inhibition of BTAH to the Ag electrode. The SERS results were well consistent with the cyclic voltammetry and polarization curves measurements. For modeling, two different surface complexes were prepared in acetonitrile with and without pph(3) by direct electrochemical synthesis. A polymer-like complex of [Ag(BTA)](n) attached to the Ag surface was obtained in the absence of pph(3), which suppressed the dissolution and oxidation of Ag effectively. A new binuclear compound, Ag(2)(BTA)(2)(pph(3))(4), was produced in acetonitrile with pph(3) and the final coordination process occurred in solution leading to difficulties in forming a compact surface film, thus decreasing the corrosion inhibition efficiency of BTAH. The role of pph(3) and the mechanism were proposed.

  6. Dusty-Plasma Particle Accelerator

    NASA Technical Reports Server (NTRS)

    Foster, John E.

    2005-01-01

    A dusty-plasma apparatus is being investigated as means of accelerating nanometer- and micrometer-sized particles. Applications for the dusty-plasma particle accelerators fall into two classes: Simulation of a variety of rapidly moving dust particles and micrometeoroids in outer-space environments that include micrometeoroid streams, comet tails, planetary rings, and nebulae and Deposition or implantation of nanoparticles on substrates for diverse industrial purposes that could include hardening, increasing thermal insulation, altering optical properties, and/or increasing permittivities of substrate materials. Relative to prior apparatuses used for similar applications, dusty-plasma particle accelerators offer such potential advantages as smaller size, lower cost, less complexity, and increased particle flux densities. A dusty-plasma particle accelerator exploits the fact that an isolated particle immersed in plasma acquires a net electric charge that depends on the relative mobilities of electrons and ions. Typically, a particle that is immersed in a low-temperature, partially ionized gas, wherein the average kinetic energy of electrons exceeds that of ions, causes the particle to become negatively charged. The particle can then be accelerated by applying an appropriate electric field. A dusty-plasma particle accelerator (see figure) includes a plasma source such as a radio-frequency induction discharge apparatus containing (1) a shallow cup with a biasable electrode to hold the particles to be accelerated and (2) a holder for the substrate on which the particles are to impinge. Depending on the specific design, a pair of electrostatic-acceleration grids between the substrate and discharge plasma can be used to both collimate and further accelerate particles exiting the particle holder. Once exposed to the discharge plasma, the particles in the cup quickly acquire a negative charge. Application of a negative voltage pulse to the biasable electrode results in the

  7. Status of Proton Polarization in Rhic and AGS

    NASA Astrophysics Data System (ADS)

    Mackay, W. W.; Bai, M.; Huang, H.; Ahrens, L.; Alekseev, I. G.; Bravar, A.; Brown, K.; Bunce, G.; Calaga, R.; Courant, E. D.; Drees, A.; Fischer, W.; Gardner, C.; Glenn, J. W.; Gupta, R.; Igo, G.; Iriso, U.; Jinnouchi, O.; Kurita, K.; Luccio, A. U.; Luo, Y.; Makdisi, Y.; Marr, G.; Montag, C.; Nass, A.; Okada, H.; Okamura, M.; Pilat, F.; Ptitsyn, V.; Roser, T.; Saito, N.; Satogata, T.; Spinka, H.; Stephenson, E. J.; Svirida, D. N.; Takano, J.; Tepikian, S.; Tomas, R.; Tsoupas, N.; Underwood, D.; Whitten, C.; Wood, J.; Zeijts, J. Van; Zelenski, A.; Zeno, K.; Zhang, S. Y.

    2005-08-01

    The Relativistic Heavy Ion Collider (RHIC) has collided protons with both transverse and longitudinal polarization at a centre-of-mass energy of 200 GeV. Future running will extend this to 500 GeV. This paper describes the methods used to accelerate and manipulate polarized proton beams in RHIC and its injectors. Special techniques include the use of a partial Siberian snake and an AC dipole in the AGS. In RHIC we use superconducting helical Siberian snakes for acceleration, and eight superconducting helical rotators for independent control of polarization directions at two interaction regions. The present status and future plans for the polarized proton program will be reviewed.

  8. Three Stages of the NICA Accelerator Complex

    NASA Astrophysics Data System (ADS)

    Kekelidze, V. D.; Lednicky, R.; Matveev, V. A.; Meshkov, I. N.; Sorin, A. S.; Trubnikov, G. V.

    2016-01-01

    The Nuclotron-based Ion Collider fAcility (NICA) project is under development at JINR (Dubna). The general goals of the project are to provide colliding beams for experimental studies of both hot and dense strongly interacting baryonic matter and spin physics (in collisions of polarized protons and deuterons). The first program will require the running of heavy ion mode in the energy range of √sNN = 4÷11 GeV at an average luminosity of L = 1•1027 cm-2-s-1 for 197Au79 nuclei. This stage of the project will be preceded by fixed target experiments with the heavy ion beam to be extracted from the Nuclotron at kinetic energies up to 4.5 GeV/u. The polarized beam mode is proposed to be used in the energy range of √sNN = 12÷27 GeV (protons) at luminosities up to 1 • 1032 cm-2-s-1. This report contains a brief description of the facility scheme and characteristics in the heavy ion operation mode, the description of the MultiPurpose Detector (MPD), and characteristics of the reactions of the colliding ions, which will allow us to detect the mixed phase formation. The plans and status of the project development are presented.

  9. Three stages of the NICA accelerator complex

    NASA Astrophysics Data System (ADS)

    Kekelidze, V. D.; Lednicky, R.; Matveev, V. A.; Meshkov, I. N.; Sorin, A. S.; Trubnikov, G. V.

    2016-08-01

    The Nuclotron-based Ion Collider fAcility (NICA) project is under development at JINR (Dubna). The general goals of the project are to provide colliding beams for experimental studies of both hot and dense strongly interacting baryonic matter and spin physics (in collisions of polarized protons and deuterons). The first program will require the running of heavy-ion mode in the energy range of √{s_{NN}} = 4-11 GeV at luminosities up to L = 1\\cdot 10^{27} cm-2 s-1 for 197Au79 nuclei (see details in sect. 4). This stage of the project will be preceded by fixed target experiments with the heavy-ion beam to be extracted from the Nuclotron at kinetic energies up to 4.5 GeV/u. The polarized beam mode is proposed to be used in the energy range of √{s_{NN}} = 12-27 GeV (protons) at luminosities up to 1\\cdot 10^{32} cm-2 s-1. This report contains a brief description of the facility scheme and characteristics in the heavy-ion operation mode, the description of the MultiPurpose Detector (MPD), and characteristics of the reactions of the colliding ions, which will allow us to detect the mixed phase formation. The plans and status of the project development are presented.

  10. Commnity Petascale Project for Accelerator Science and Simulation: Advancing Computational Science for Future Accelerators and Accelerator Technologies

    SciTech Connect

    Spentzouris, Panagiotis; Cary, John; Mcinnes, Lois Curfman; Mori, Warren; Ng, Cho; Ng, Esmond; Ryne, Robert; /LBL, Berkeley

    2008-07-01

    The design and performance optimization of particle accelerators is essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC1 Accelerator Science and Technology project, the SciDAC2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modeling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multi-physics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.

  11. Commnity Petascale Project for Accelerator Science And Simulation: Advancing Computational Science for Future Accelerators And Accelerator Technologies

    SciTech Connect

    Spentzouris, Panagiotis; Cary, John; Mcinnes, Lois Curfman; Mori, Warren; Ng, Cho; Ng, Esmond; Ryne, Robert; /LBL, Berkeley

    2011-10-21

    The design and performance optimization of particle accelerators are essential for the success of the DOE scientific program in the next decade. Particle accelerators are very complex systems whose accurate description involves a large number of degrees of freedom and requires the inclusion of many physics processes. Building on the success of the SciDAC-1 Accelerator Science and Technology project, the SciDAC-2 Community Petascale Project for Accelerator Science and Simulation (ComPASS) is developing a comprehensive set of interoperable components for beam dynamics, electromagnetics, electron cooling, and laser/plasma acceleration modelling. ComPASS is providing accelerator scientists the tools required to enable the necessary accelerator simulation paradigm shift from high-fidelity single physics process modeling (covered under SciDAC1) to high-fidelity multiphysics modeling. Our computational frameworks have been used to model the behavior of a large number of accelerators and accelerator R&D experiments, assisting both their design and performance optimization. As parallel computational applications, the ComPASS codes have been shown to make effective use of thousands of processors.

  12. Longitudinal emittance measurements in the Booster and AGS during the 2014 RHIC gold run

    SciTech Connect

    Zeno, K.

    2014-08-18

    This note describes longitudinal emittance measurements that were made in the Booster and AGS during the 2014 RHIC Gold run. It also contains an overview of the longitudinal aspects of their setup during this run. Each bunch intended for RHIC is composed of beam from 4 Booster cycles, and there are two of them per AGS cycle. For each of the 8 Booster cycles required to produce the 2 bunches in the AGS, a beam pulse from EVIS is injected into the Booster and captured in four h=4 buckets. Then those bunches are accelerated to a porch where they are merged into 2 bunches and then into 1 bunch.

  13. Evaluation of an immunochromatographic assay for rapid identification of Mycobacterium tuberculosis complex in clinical isolates.

    PubMed

    Marzouk, Manel; Kahla, Imen Ben; Hannachi, Naila; Ferjeni, Asma; Salma, Walid Ben; Ghezal, Samira; Boukadida, Jalel

    2011-04-01

    Identification of Mycobacterium tuberculosis complex (MTC) remains slow. Over the years, several new technologies have been proposed to accelerate and simplify the detection of MTC. In this context, we evaluated an immunochromatographic assay (ICA) (BIO-LINE SD Ag MPT64 TB) for rapid identification of MTC, based on detection of a specific MPT64 antigen of MTC. We have tested it on i) mycobacterial cultures: 210 MTC strains and 28 nontuberculous mycobacteria; ii) M. bovis bacille Calmette-Guérin strain SSI (Statens Serum Institut, Denmark); and iii) 22 microorganisms other than mycobacteria, isolated from cultures. We concluded that this kit has an excellent specificity (100%) and sensitivity (99%) from isolated cultures. The ICA (BIO-LINE SD Ag MPT64 TB) allows excellent MTC identification from clinical isolates. It is a rapid, simple, and inexpensive test, and has a definite contribution in the rapid laboratory diagnosis of tuberculosis.

  14. Accelerating Particles with Plasma

    ScienceCinema

    Litos, Michael; Hogan, Mark

    2016-07-12

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  15. Peak acceleration limiter

    NASA Technical Reports Server (NTRS)

    Chapman, C. P.

    1972-01-01

    Device is described that limits accelerations by shutting off shaker table power very rapidly in acceleration tests. Absolute value of accelerometer signal is used to trigger electronic switch which terminates test and sounds alarm.

  16. Linear Accelerator (LINAC)

    MedlinePlus

    ... equipment? How is safety ensured? What is this equipment used for? A linear accelerator (LINAC) is the ... Therapy (SBRT) . top of page How does the equipment work? The linear accelerator uses microwave technology (similar ...

  17. Accelerating Particles with Plasma

    SciTech Connect

    Litos, Michael; Hogan, Mark

    2014-11-05

    Researchers at SLAC explain how they use plasma wakefields to accelerate bunches of electrons to very high energies over only a short distance. Their experiments offer a possible path for the future of particle accelerators.

  18. Improved plasma accelerator

    NASA Technical Reports Server (NTRS)

    Cheng, D. Y.

    1971-01-01

    Converging, coaxial accelerator electrode configuration operates in vacuum as plasma gun. Plasma forms by periodic injections of high pressure gas that is ionized by electrical discharges. Deflagration mode of discharge provides acceleration, and converging contours of plasma gun provide focusing.

  19. Accelerator Technology Division

    NASA Astrophysics Data System (ADS)

    1992-04-01

    In fiscal year (FY) 1991, the Accelerator Technology (AT) division continued fulfilling its mission to pursue accelerator science and technology and to develop new accelerator concepts for application to research, defense, energy, industry, and other areas of national interest. This report discusses the following programs: The Ground Test Accelerator Program; APLE Free-Electron Laser Program; Accelerator Transmutation of Waste; JAERI, OMEGA Project, and Intense Neutron Source for Materials Testing; Advanced Free-Electron Laser Initiative; Superconducting Super Collider; The High-Power Microwave Program; (Phi) Factory Collaboration; Neutral Particle Beam Power System Highlights; Accelerator Physics and Special Projects; Magnetic Optics and Beam Diagnostics; Accelerator Design and Engineering; Radio-Frequency Technology; Free-Electron Laser Technology; Accelerator Controls and Automation; Very High-Power Microwave Sources and Effects; and GTA Installation, Commissioning, and Operations.

  20. 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.

  1. Accelerators, Colliders, and Snakes

    NASA Astrophysics Data System (ADS)

    Courant, Ernest D.

    2003-12-01

    The author traces his involvement in the evolution of particle accelerators over the past 50 years. He participated in building the first billion-volt accelerator, the Brookhaven Cosmotron, which led to the introduction of the "strong-focusing" method that has in turn led to the very large accelerators and colliders of the present day. The problems of acceleration of spin-polarized protons are also addressed, with discussions of depolarizing resonances and "Siberian snakes" as a technique for mitigating these resonances.

  2. Reversible modulated mid-infrared absorption of Ag/TiO{sub 2} by photoinduced interfacial charge transfer

    SciTech Connect

    Xu, S. C. E-mail: ghli@issp.ac.cn; Li, L.; Pan, S. S.; Luo, Y. Y.; Zhang, Y. X.; Li, G. H. E-mail: ghli@issp.ac.cn

    2014-10-06

    An enhanced mid-infrared absorption in Ag nanoparticles-decorated TiO{sub 2} microflowers was reported. It was found that the mid-infrared absorption of the Ag/TiO{sub 2} complex depends strongly on the content and size of Ag nanoparticles, the higher the Ag nanoparticles content, the stronger the infrared absorption. The average reflectivity in the entire mid-infrared region of the microflowers drops from 57.6% to 10.5% after Ag nanoparticles decoration. Reversible modulated mid-infrared absorption properties were found in the Ag/TiO{sub 2} complexes upon alternative illumination of visible and UV light due to the photoinduced interfacial electron transfer between TiO{sub 2} semiconductor and Ag nanoparticles.

  3. 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.

  4. Acceleration: It's Elementary

    ERIC Educational Resources Information Center

    Willis, Mariam

    2012-01-01

    Acceleration is one tool for providing high-ability students the opportunity to learn something new every day. Some people talk about acceleration as taking a student out of step. In actuality, what one is doing is putting a student in step with the right curriculum. Whole-grade acceleration, also called grade-skipping, usually happens between…

  5. Angular Acceleration without Torque?

    ERIC Educational Resources Information Center

    Kaufman, Richard D.

    2012-01-01

    Hardly. Just as Robert Johns qualitatively describes angular acceleration by an internal force in his article "Acceleration Without Force?" here we will extend the discussion to consider angular acceleration by an internal torque. As we will see, this internal torque is due to an internal force acting at a distance from an instantaneous center.

  6. Accelerated test design

    NASA Technical Reports Server (NTRS)

    Mcdermott, P. P.

    1980-01-01

    The design of an accelerated life test program for electric batteries is discussed. A number of observations and suggestions on the procedures and objectives for conducting an accelerated life test program are presented. Equations based on nonlinear regression analysis for predicting the accelerated life test parameters are discussed.

  7. Long-term transformation and fate of manufactured ag nanoparticles in a simulated large scale freshwater emergent wetland.

    PubMed

    Lowry, Gregory V; Espinasse, Benjamin P; Badireddy, Appala Raju; Richardson, Curtis J; Reinsch, Brian C; Bryant, Lee D; Bone, Audrey J; Deonarine, Amrika; Chae, Soryong; Therezien, Mathieu; Colman, Benjamin P; Hsu-Kim, Heileen; Bernhardt, Emily S; Matson, Cole W; Wiesner, Mark R

    2012-07-03

    Transformations and long-term fate of engineered nanomaterials must be measured in realistic complex natural systems to accurately assess the risks that they may pose. Here, we determine the long-term behavior of poly(vinylpyrrolidone)-coated silver nanoparticles (AgNPs) in freshwater mesocosms simulating an emergent wetland environment. AgNPs were either applied to the water column or to the terrestrial soils. The distribution of silver among water, solids, and biota, and Ag speciation in soils and sediment was determined 18 months after dosing. Most (70 wt %) of the added Ag resided in the soils and sediments, and largely remained in the compartment in which they were dosed. However, some movement between soil and sediment was observed. Movement of AgNPs from terrestrial soils to sediments was more facile than from sediments to soils, suggesting that erosion and runoff is a potential pathway for AgNPs to enter waterways. The AgNPs in terrestrial soils were transformed to Ag(2)S (~52%), whereas AgNPs in the subaquatic sediment were present as Ag(2)S (55%) and Ag-sulfhydryl compounds (27%). Despite significant sulfidation of the AgNPs, a fraction of the added Ag resided in the terrestrial plant biomass (~3 wt % for the terrestrially dosed mesocosm), and relatively high body burdens of Ag (0.5-3.3 μg Ag/g wet weight) were found in mosquito fish and chironomids in both mesocosms. Thus, Ag from the NPs remained bioavailable even after partial sulfidation and when water column total Ag concentrations are low (<0.002 mg/L).

  8. 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.

  9. 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.

  10. 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.

  11. Fiber Accelerating Structures

    SciTech Connect

    Hammond, Andrew P.; /Reed Coll. /SLAC

    2010-08-25

    One of the options for future particle accelerators are photonic band gap (PBG) fiber accelerators. PBG fibers are specially designed optical fibers that use lasers to excite an electric field that is used to accelerate electrons. To improve PBG accelerators, the basic parameters of the fiber were tested to maximize defect size and acceleration. Using the program CUDOS, several accelerating modes were found that maximized these parameters for several wavelengths. The design of multiple defects, similar to having closely bound fibers, was studied to find possible coupling or the change of modes. The amount of coupling was found to be dependent on distance separated. For certain distances accelerating coupled modes were found and examined. In addition, several non-periodic fiber structures were examined using CUDOS. The non-periodic fibers produced several interesting results and promised more modes given time to study them in more detail.

  12. High brightness electron accelerator

    DOEpatents

    Sheffield, Richard L.; Carlsten, Bruce E.; Young, Lloyd M.

    1994-01-01

    A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of acclerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electons as the electrons enter the first cavity.

  13. Acceleration in astrophysics

    SciTech Connect

    Colgate, S.A.

    1993-12-31

    The origin of cosmic rays and applicable laboratory experiments are discussed. Some of the problems of shock acceleration for the production of cosmic rays are discussed in the context of astrophysical conditions. These are: The presumed unique explanation of the power law spectrum is shown instead to be a universal property of all lossy accelerators; the extraordinary isotropy of cosmic rays and the limited diffusion distances implied by supernova induced shock acceleration requires a more frequent and space-filling source than supernovae; the near perfect adiabaticity of strong hydromagnetic turbulence necessary for reflecting the accelerated particles each doubling in energy roughly 10{sup 5} to {sup 6} scatterings with negligible energy loss seems most unlikely; the evidence for acceleration due to quasi-parallel heliosphere shocks is weak. There is small evidence for the expected strong hydromagnetic turbulence, and instead, only a small number of particles accelerate after only a few shock traversals; the acceleration of electrons in the same collisionless shock that accelerates ions is difficult to reconcile with the theoretical picture of strong hydromagnetic turbulence that reflects the ions. The hydromagnetic turbulence will appear adiabatic to the electrons at their much higher Larmor frequency and so the electrons should not be scattered incoherently as they must be for acceleration. Therefore the electrons must be accelerated by a different mechanism. This is unsatisfactory, because wherever electrons are accelerated these sites, observed in radio emission, may accelerate ions more favorably. The acceleration is coherent provided the reconnection is coherent, in which case the total flux, as for example of collimated radio sources, predicts single charge accelerated energies much greater than observed.

  14. Ab initio study of edge smoothing, atom attraction, and downward funneling in Ag/Ag(100)

    NASA Astrophysics Data System (ADS)

    Shim, Yunsic; Amar, Jacques G.

    2011-06-01

    The results of density-functional theory (DFT) calculations of the energy barriers for three low-barrier relaxation processes in Ag/Ag(100) growth—edge-zipping, atom attraction, and downward funneling—are presented and compared with embedded atom method (EAM) calculations. In general, we find good agreement between the DFT values for these processes and the values assumed in recent simulations of low-temperature Ag/Ag(100) growth [Shim and Amar, Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.81.045416 81, 045416 (2010)]. We also find reasonable agreement between our DFT results and the results of EAM calculations, although in a few specific cases there is a noticeable disagreement. In order to investigate the effects of long-range interactions, we have also carried out additional calculations for more complex configurations. While our EAM results indicate that long-range interactions such as “pinning” can significantly enhance the energy barriers for edge-zipping and atom attraction, these effects can be significantly weaker in our DFT calculations due to the redistribution of the electron density.

  15. Effect of toxicity of Ag nanoparticles on SERS spectral variance of bacteria

    NASA Astrophysics Data System (ADS)

    Cui, Li; Chen, Shaode; Zhang, Kaisong

    2015-02-01

    Ag nanoparticles (NPs) have been extensively utilized in surface-enhanced Raman scattering (SERS) spectroscopy for bacterial identification. However, Ag NPs are toxic to bacteria. Whether such toxicity can affect SERS features of bacteria and interfere with bacterial identification is still unknown and needed to explore. Here, by carrying out a comparative study on non-toxic Au NPs with that on toxic Ag NPs, we investigated the influence of nanoparticle concentration and incubation time on bacterial SERS spectral variance, both of which were demonstrated to be closely related to the toxicity of Ag NPs. Sensitive spectral alterations were observed on Ag NPs with increase of NPs concentration or incubation time, accompanied with an obvious decrease in number of viable bacteria. In contrast, SERS spectra and viable bacterial number on Au NPs were rather constant under the same conditions. A further analysis on spectral changes demonstrated that it was cell response (i.e. metabolic activity or death) to the toxicity of Ag NPs causing spectral variance. However, biochemical responses to the toxicity of Ag were very different in different bacteria, indicating the complex toxic mechanism of Ag NPs. Ag NPs are toxic to a great variety of organisms, including bacteria, fungi, algae, protozoa etc., therefore, this work will be helpful in guiding the future application of SERS technique in various complex biological systems.

  16. Application of a new coordination compound for the preparation of AgI nanoparticles

    SciTech Connect

    Mohandes, Fatemeh; Salavati-Niasari, Masoud

    2013-10-15

    Graphical abstract: Silver iodide nanoparticles have been sonochemically synthesized by using silver salicylate complex, [Ag(HSal)], as silver precursor. A series of control experiments were carried out to investigate the effects of solvent, surfactant concentration, sonication time and temperature on the morphology of AgI nanostructures. - Highlights: • Silver salicylate as a new precursor was applied to fabricate γ-AgI nanoparticles. • To further decrease the particle size of AgI, SDS was used as surfactant. • The effect of preparation parameters on the particle size of AgI was investigated. - Abstract: AgI nanoparticles have been sonochemically synthesized by using silver salicylate, [Ag(HSal)], as silver precursor. To investigate the effects of solvent, surfactant concentration, sonication time and temperature on the morphology of AgI nanostructures, several experiments were carried out. The products were characterized by SEM, TEM, XRD, TGA/DTA, UV–vis, and FT-IR. Based on the experimental findings in this research, it was found that the size of AgI nanoparticles was dramatically dependent on the silver precursor, sonochemical irradiation, and surfactant concentration. Sodium dodecyl sulfate (SDS) was applied as surfactant. When the concentration of SDS was 0.055 mM, very uniform sphere-like AgI nanoparticles with grain size of about 25–30 nm were obtained. These results indicated that the high concentration of SDS could prevent the aggregation between colloidal nanoparticles due to its steric hindrance effect.

  17. Reversible vertical manipulation of Ag atoms on Si(111)-(74 ×7) at room temperature

    NASA Astrophysics Data System (ADS)

    Ming, Fangfei; Wang, Kedong; Pan, Shuan; Liu, Jiepeng; Zhang, Xieqiu; Yang, Jinlong; Xiao, Xudong; Department of Physics, Chinese University of Hong Kong, Shatin, New Territory, Hong Kong, China Team; Hefei National LaboratoryPhysical Sciences At Microscales, University of Science; Technolog Team

    2011-03-01

    We have demonstrated a technique to conduct reproducible and reversible vertical manipulation of Ag atoms on the Si(111)-(7 × 7) surface at room temperature using a scanning tunneling microscope tip. The direction of the transfer of Ag atoms between the sample surface and the tip is simply controlled by the polarity of the bias voltage. Using the 7 × 7 unit cell as a nanometer size template, complex Ag nano-clusters could be assembled or disassembled by adding or removing Ag atoms in an atom-by-atom manner. With controlled number of Ag atoms filled in a half unit cell, we can construct Ag clusters with up to 25 Ag atoms. The precise control of the number of Ag atoms in the Ag clusters can provide critical information for understanding their physical and chemical properties, and form a fundamental base for the relevant studies of the Ag/Si(111)-(7 × 7) system and for fabricating nano-devices.

  18. Radiolytic production of Ag-containing nanocomposite colloids in presence of lithium ions.

    PubMed

    Im, Hee-Jung; Choi, Kwang-Soon

    2012-07-01

    This research is motivated to prepare homogeneous and less aggregated nanostructured composites for potential scintillators. Poly ethylene glycol (PEG)-protected approximately 5 nm and approximately 29 nm sized Ag nanoparticles and Ag-Zn nanocomposites were relatively prepared by electron-beam irradiation on Ag+ and Zn2+ solutions with the aids of stabilizers and 6Li+ at room temperature under atmospheric pressure. Especially the 6Li+, which was used for a neutron absorption purpose, played a part the Ag-Zn nanocolloids to less aggregate in the aqueous phase by making partial complexes with stabilizers containing Ag-Zn. To be a potential scintillator, the Ag-Zn nanocomposites have to show an optical response to radiation. Therefore, optical luminescence, which resembles the concept of detecting light without the requirement of a neutron absorbent (convertor) for a neutron scitillator, of the nanocomposites was tested.

  19. Increased intensity performance of the Brookhaven AGS

    SciTech Connect

    Raka, E.; Ahrens, L.; Frey, W.; Gill, E.; Glenn, J.W.; Sanders, R.; Weng, W.

    1985-05-01

    With the advent of H/sup -/ injection into the Brookhaven AGS, circulating beams of up to 3 x 10/sup 13/ protons at 200 MeV have been obtained. Rf capture of 2.2 x 10/sup 13/ and acceleration of 1.73 x 10/sup 13/ up to the transition energy (approx. = 8 GeV) and 1.64 x 10/sup 13/ to full energy (approx. = 29 GeV) has been achieved. This represents a 50% increase over the best performance obtained with H/sup +/ injection. The increase in circulation beam current is obtained without filling the horizontal aperture. This allows the rf capture process to utilize a larger longitudinal phase space area (approx. = 1 eV sec/bunch vs less than or equal to 0.6 eV sec with H/sup +/ operation). The resulting reduction in relative longitudinal density partially offsets the increase in space charge effects at higher currents. In order to make the capture process independent of injected beam current, a dynamic beam loading compensation loop was installed on the AGS rf system. This is the only addition to the synchrotron itself that was required to reach the new intensity records. A discussion of injection, the rf capture process, and space charge effects is presented. 9 refs., 5 figs.

  20. Adsorption, vibration and diffusion of oxygen on Ag(110)

    NASA Astrophysics Data System (ADS)

    Rawal, Takat; Hong, Sampyo; Pulkkinen, Aki; Alatalo, Matti; Rahman, Talat

    2015-03-01

    We have performed density functional theory calculations for the adsorption, vibration and diffusion of oxygen on Ag(110). At low coverage, O2 adsorbs at the four-fold hollow (FFH) with the molecular axis aligned along the [ 1 1 0 ] direction. The dissociation of O2 is easier along the [001] direction than along the [ 1 1 0 ] direction. For O2 species in FFH aligned along the [001] the O-O intra-molecular stretching mode is coupled with the substrate vibration and thus its dissociation can be induced by surface phonon. In addition, O diffusion barrier from FFH to next FFH along the [ 1 1 0 ] is small (0.07 eV only) but is by far larger (0.4 eV) along [001]. On the other hand, O species in the short-bride (SB) site prefers to diffuse along the [001] (to FFH) rather than along the [ 1 1 0 ] direction (to next SB). Finally, the preference of atomic oxygen to form O-Ag-O complex on Ag(110) is responsible for disordering of the surface by means of substantial lateral and vertical displacements of Ag atoms in the topmost layer. In fact, such disordering phase of Ag(110) may act as a precursor of the reconstructed phase of Ag(110). Work supported in part by NSF under Grant CHE-1310327.

  1. Oxygen reduction reaction on Cu-doped Ag cluster for fuel-cell cathode.

    PubMed

    Ma, Wenqiang; Chen, Fuyi; Zhang, Nan; Wu, Xiaoqiang

    2014-10-01

    The development of fuel cells as clean-energy technologies is largely limited by the prohibitive cost of the noble-metal catalysts needed for catalyzing the oxygen reduction reaction (ORR) in fuel cells. A fundamental understanding of catalyst design principle that links material structures to the catalytic activity can accelerate the search for highly active and abundant bimetallic catalysts to replace platinum. Here, we present a first-principles study of ORR on Ag12Cu cluster in alkaline environment. The adsorptions of O2, OOH, and OH on Cu-doped Ag13 are stronger than on Ag13. The d-band centers of adsorption sites show the Cu-doping makes d-electrons transferred to higher energy state, and improves O2 dissociation. ORR processes on Ag12Cu and Ag13 indicate Cu-doping can strongly promote ORR, and ORR process can be better preformed on Ag12Cu than on Ag13. For four-electron transfer, the effective reversible potential is 0.401 V/RHE on Ag12Cu in alkaline medium.

  2. Rf beam control for the AGS Booster

    SciTech Connect

    Brennan, J.M.

    1994-09-26

    RF beam control systems for hadron synchrotrons have evolved over the past three decades into an essentially standard design. The key difference between hadron and lepton machines is the absence of radiation damping and existence of significant frequency variation in the case of hadrons. Although the motion of the hadron in the potential well of the rf wave is inherently stable it is not strongly damped. Damping must be provided by electronic feedback through the accelerating system. This feedback is typically called the phase loop. The technology of the rf beam control system for the AGS Booster synchrotron is described. First, the overall philosophy of the design is explained in terms of a conventional servo system that regulates the beam horizontal position in the vacuum chamber. The concept of beam transfer functions is fundamental to the mathematics of the design process and is reviewed. The beam transfer functions required for this design are derived from first principles. An overview of the beam signal pick-ups and high level rf equipment is given. The major subsystems, the frequency program, the heterodyne system, and beam feedback loops, are described in detail. Beyond accelerating the beam, the rf system must also synchronize the bunches in the Booster to the buckets in the AGS before transfer. The technical challenge in this process is heightened by the need to accomplish synchronization while the frequency is still changing. Details of the synchronization system are given. This report is intended to serve two purposes. One is to document the hardware and performance of the systems that have been built. The other is to serve as a tutorial vehicle from which the non-expert can not only learn the details of this system but also learn the principles of beam control that have led to the particular design choices made.

  3. 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.

  4. 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.

  5. 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…

  6. Structural and electronic analysis of the atomic scale nucleation of Ag on α-Ag2WO4 induced by electron irradiation

    PubMed Central

    Andrés, Juan; Gracia, Lourdes; Gonzalez-Navarrete, Patricio; Longo, Valeria M.; Avansi, Waldir; Volanti, Diogo P.; Ferrer, Mateus M.; Lemos, Pablo S.; La Porta, Felipe A.; Hernandes, Antonio C.; Longo, Elson

    2014-01-01

    In this work, we utilise a combination of theory, computation and experiments to understand the early events related to the nucleation of Ag filaments on α-Ag2WO4 crystals, which is driven by an accelerated electron beam from an electron microscope under high vacuum. The growth process and the chemical composition and elemental distribution in these filaments were analysed in depth at the nanoscale level using TEM, HAADF, EDS and XPS; the structural and electronic aspects were systematically studied in using first-principles electronic structure theory within QTAIM framework. The Ag nucleation and formation on α-Ag2WO4 is a result of the order/disorder effects generated in the crystal by the electron-beam irradiation. Both experimental and theoretical results show that this behavior is associated with structural and electronic changes of the [AgO2] and [AgO4] clusters and, to a minor extent, to the [WO6] cluster; these clusters collectively represent the constituent building blocks of α-Ag2WO4. PMID:24953210

  7. An introduction to acceleration mechanisms

    SciTech Connect

    Palmer, R.B.

    1987-05-01

    This paper discusses the acceleration of charged particles by electromagnetic fields, i.e., by fields that are produced by the motion of other charged particles driven by some power source. The mechanisms that are discussed include: Ponderamotive Forces, Acceleration, Plasma Beat Wave Acceleration, Inverse Free Electron Laser Acceleration, Inverse Cerenkov Acceleration, Gravity Acceleration, 2D Linac Acceleration and Conventional Iris Loaded Linac Structure Acceleration. (LSP)

  8. 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.

  9. 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.

  10. 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

  11. Dynamically Reconfigurable Systolic Array Accelerator

    NASA Technical Reports Server (NTRS)

    Dasu, Aravind; Barnes, Robert

    2012-01-01

    A polymorphic systolic array framework has been developed that works in conjunction with an embedded microprocessor on a field-programmable gate array (FPGA), which allows for dynamic and complimentary scaling of acceleration levels of two algorithms active concurrently on the FPGA. Use is made of systolic arrays and a hardware-software co-design to obtain an efficient multi-application acceleration system. The flexible and simple framework allows hosting of a broader range of algorithms, and is extendable to more complex applications in the area of aerospace embedded systems. FPGA chips can be responsive to realtime demands for changing applications needs, but only if the electronic fabric can respond fast enough. This systolic array framework allows for rapid partial and dynamic reconfiguration of the chip in response to the real-time needs of scalability, and adaptability of executables.

  12. Accelerated Adaptive Integration Method

    PubMed Central

    2015-01-01

    Conformational changes that occur upon ligand binding may be too slow to observe on the time scales routinely accessible using molecular dynamics simulations. The adaptive integration method (AIM) leverages the notion that when a ligand is either fully coupled or decoupled, according to λ, barrier heights may change, making some conformational transitions more accessible at certain λ values. AIM adaptively changes the value of λ in a single simulation so that conformations sampled at one value of λ seed the conformational space sampled at another λ value. Adapting the value of λ throughout a simulation, however, does not resolve issues in sampling when barriers remain high regardless of the λ value. In this work, we introduce a new method, called Accelerated AIM (AcclAIM), in which the potential energy function is flattened at intermediate values of λ, promoting the exploration of conformational space as the ligand is decoupled from its receptor. We show, with both a simple model system (Bromocyclohexane) and the more complex biomolecule Thrombin, that AcclAIM is a promising approach to overcome high barriers in the calculation of free energies, without the need for any statistical reweighting or additional processors. PMID:24780083

  13. Schooling in Times of Acceleration

    ERIC Educational Resources Information Center

    Buddeberg, Magdalena; Hornberg, Sabine

    2017-01-01

    Modern societies are characterised by forms of acceleration, which influence social processes. Sociologist Hartmut Rosa has systematised temporal structures by focusing on three categories of social acceleration: technical acceleration, acceleration of social change, and acceleration of the pace of life. All three processes of acceleration are…

  14. Uniformly accelerated black holes

    NASA Astrophysics Data System (ADS)

    Letelier, Patricio S.; Oliveira, Samuel R.

    2001-09-01

    The static and stationary C metric are examined in a generic framework and their interpretations studied in some detail, especially those with two event horizons, one for the black hole and another for the acceleration. We find that (i) the spacetime of an accelerated static black hole is plagued by either conical singularities or a lack of smoothness and compactness of the black hole horizon, (ii) by using standard black hole thermodynamics we show that accelerated black holes have a higher Hawking temperature than Unruh temperature of the accelerated frame, and (iii) the usual upper bound on the product of the mass and acceleration parameters (<1/27) is just a coordinate artifact. The main results are extended to accelerated rotating black holes with no significant changes.

  15. The Dielectric Wall Accelerator

    SciTech Connect

    Caporaso, George J.; Chen, Yu-Jiuan; Sampayan, Stephen E.

    2009-01-01

    The Dielectric Wall Accelerator (DWA), a class of induction accelerators, employs a novel insulating beam tube to impress a longitudinal electric field on a bunch of charged particles. The surface flashover characteristics of this tube may permit the attainment of accelerating gradients on the order of 100 MV/m for accelerating pulses on the order of a nanosecond in duration. A virtual traveling wave of excitation along the tube is produced at any desired speed by controlling the timing of pulse generating modules that supply a tangential electric field to the tube wall. Because of the ability to control the speed of this virtual wave, the accelerator is capable of handling any charge to mass ratio particle; hence it can be used for electrons, protons and any ion. The accelerator architectures, key technologies and development challenges will be described.

  16. Optically pulsed electron accelerator

    DOEpatents

    Fraser, J.S.; Sheffield, R.L.

    1985-05-20

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radiofrequency-powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  17. Optically pulsed electron accelerator

    DOEpatents

    Fraser, John S.; Sheffield, Richard L.

    1987-01-01

    An optically pulsed electron accelerator can be used as an injector for a free electron laser and comprises a pulsed light source, such as a laser, for providing discrete incident light pulses. A photoemissive electron source emits electron bursts having the same duration as the incident light pulses when impinged upon by same. The photoemissive electron source is located on an inside wall of a radio frequency powered accelerator cell which accelerates the electron burst emitted by the photoemissive electron source.

  18. ACCELERATION RESPONSIVE SWITCH

    DOEpatents

    Chabrek, A.F.; Maxwell, R.L.

    1963-07-01

    An acceleration-responsive device with dual channel capabilities whereby a first circuit is actuated upon attainment of a predetermined maximum acceleration level and when the acceleration drops to a predetermined minimum acceleriltion level another circuit is actuated is described. A fluid-damped sensing mass slidably mounted in a relatively frictionless manner on a shaft through the intermediation of a ball bushing and biased by an adjustable compression spring provides inertially operated means for actuating the circuits. (AEC)

  19. The foxhole accelerating structure

    SciTech Connect

    Fernow, R.C.; Claus, J.

    1992-07-17

    This report examines some properties of a new type of open accelerating structure. It consists of a series of rectangular cavities, which we call foxholes, joined by a beam channel. The power for accelerating the particles comes from an external radiation source and enters the cavities through their open upper surfaces. Analytic and computer calculations are presented showing that the foxhole is a suitable structure for accelerating relativistic electrons.

  20. 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.

  1. Particle acceleration in flares

    NASA Technical Reports Server (NTRS)

    Benz, Arnold O.; Kosugi, Takeo; Aschwanden, Markus J.; Benka, Steve G.; Chupp, Edward L.; Enome, Shinzo; Garcia, Howard; Holman, Gordon D.; Kurt, Victoria G.; Sakao, Taro

    1994-01-01

    Particle acceleration is intrinsic to the primary energy release in the impulsive phase of solar flares, and we cannot understand flares without understanding acceleration. New observations in soft and hard X-rays, gamma-rays and coherent radio emissions are presented, suggesting flare fragmentation in time and space. X-ray and radio measurements exhibit at least five different time scales in flares. In addition, some new observations of delayed acceleration signatures are also presented. The theory of acceleration by parallel electric fields is used to model the spectral shape and evolution of hard X-rays. The possibility of the appearance of double layers is further investigated.

  2. Charged particle accelerator grating

    DOEpatents

    Palmer, Robert B.

    1986-01-01

    A readily disposable and replaceable accelerator grating for a relativistic particle accelerator. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams into the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

  3. Charged particle accelerator grating

    DOEpatents

    Palmer, Robert B.

    1986-09-02

    A readily disposable and replaceable accelerator grating for a relativistic particle accelerator. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams into the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

  4. Accelerator-based BNCT.

    PubMed

    Kreiner, A J; Baldo, M; Bergueiro, J R; Cartelli, D; Castell, W; Thatar Vento, V; Gomez Asoia, J; Mercuri, D; Padulo, J; Suarez Sandin, J C; Erhardt, J; Kesque, J M; Valda, A A; Debray, M E; Somacal, H R; Igarzabal, M; Minsky, D M; Herrera, M S; Capoulat, M E; Gonzalez, S J; del Grosso, M F; Gagetti, L; Suarez Anzorena, M; Gun, M; Carranza, O

    2014-06-01

    The activity in accelerator development for accelerator-based BNCT (AB-BNCT) both worldwide and in Argentina is described. Projects in Russia, UK, Italy, Japan, Israel, and Argentina to develop AB-BNCT around different types of accelerators are briefly presented. In particular, the present status and recent progress of the Argentine project will be reviewed. The topics will cover: intense ion sources, accelerator tubes, transport of intense beams, beam diagnostics, the (9)Be(d,n) reaction as a possible neutron source, Beam Shaping Assemblies (BSA), a treatment room, and treatment planning in realistic cases.

  5. High Gradient Accelerator Research

    SciTech Connect

    Temkin, Richard

    2016-07-12

    The goal of the MIT program of research on high gradient acceleration is the development of advanced acceleration concepts that lead to a practical and affordable next generation linear collider at the TeV energy level. Other applications, which are more near-term, include accelerators for materials processing; medicine; defense; mining; security; and inspection. The specific goals of the MIT program are: • Pioneering theoretical research on advanced structures for high gradient acceleration, including photonic structures and metamaterial structures; evaluation of the wakefields in these advanced structures • Experimental research to demonstrate the properties of advanced structures both in low-power microwave cold test and high-power, high-gradient test at megawatt power levels • Experimental research on microwave breakdown at high gradient including studies of breakdown phenomena induced by RF electric fields and RF magnetic fields; development of new diagnostics of the breakdown process • Theoretical research on the physics and engineering features of RF vacuum breakdown • Maintaining and improving the Haimson / MIT 17 GHz accelerator, the highest frequency operational accelerator in the world, a unique facility for accelerator research • Providing the Haimson / MIT 17 GHz accelerator facility as a facility for outside users • Active participation in the US DOE program of High Gradient Collaboration, including joint work with SLAC and with Los Alamos National Laboratory; participation of MIT students in research at the national laboratories • Training the next generation of Ph. D. students in the field of accelerator physics.

  6. FFAGS for rapid acceleration

    SciTech Connect

    Carol J. Johnstone and Shane Koscielniak

    2002-09-30

    When large transverse and longitudinal emittances are to be transported through a circular machine, extremely rapid acceleration holds the advantage that the beam becomes immune to nonlinear resonances because there is insufficient time for amplitudes to build up. Uncooled muon beams exhibit large emittances and require fast acceleration to avoid decay losses and would benefit from this style of acceleration. The approach here employs a fixed-field alternating gradient or FFAG magnet structure and a fixed frequency acceleration system. Acceptance is enhanced by the use only of linear lattice elements, and fixed-frequency rf enables the use of cavities with large shunt resistance and quality factor.

  7. OVERCOMING INTRINSIC AND COUPLING SPIN RESONANCES IN THE AGS.

    SciTech Connect

    BAI,M.AHRENS,L.ROSER,T.

    2002-11-06

    In the Brookhaven AGS, polarized protons are accelerated from G{sub {gamma}} = 4.5 to G{sub {gamma}} = 46.5. During the acceleration, a total of 42 imperfection spin depolarization resonances and 7 intrinsic spin resonances are crossed. Currently, the depolarization at each imperfection spin resonance is overcome by a solenoid 5% snake and full spin flips are induced at 4 out of the 7 intrinsic resonances by the AGS rf dipole to avoid the polarization loss. No correction schemes are applied at the remaining 3 weak spin resonances. In addition, coupling spin resonances are also observed due to the solenoidal field of the snake and no correction is applied for these spin resonances other than keeping the horizontal and vertical betatron tunes separated. In order to achieve {ge} 50% beam polarization out of AGS, all of those spin resonances need to be corrected. This paper proposes three correction methods to overcome the. strong intrinsic spin resonances as well as the weak intrinsic spin resonances and the coupling spin resonances.

  8. 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.

  9. 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.

  10. Solving radiation problems at particle accelerators

    SciTech Connect

    Nikolai V. Mokhov

    2001-12-11

    At high-intensity high-energy particle accelerators, consequences of a beam-induced radiation impact on machine and detector components, people, environment and complex performance can range from negligible to severe. The specifics, general approach and tools used at such machines for radiation analysis are described. In particular, the world leader Fermilab accelerator complex is considered, with its fixed target and collider experiments, as well as new challenging projects such as LHC, VLHC, muon collider and neutrino factory. The emphasis is on mitigation of deleterious beam-induced radiation effects and on the key role of effective computer simulations.

  11. Characterization of Low Melting Temperature, Low-Ag, Bi-Containing, Pb-Free Solder Alloys

    NASA Astrophysics Data System (ADS)

    Kosiba, Eva

    Restrictions of lead in solder lead to adoption of SAC305 in consumer products. While high reliability applications use SnPb, supply constraints are driving the adoption of a replacement. SAC305 has reliability concerns related to elevated process temperatures and the formation of Ag3Sn. Reliability performance of three low-Ag, Bi-containing, low melting temperature alloys were compared to SAC305. All three alloys under test performed as well or better for consumer applications. Drop testing and accelerated thermal cycling revealed no differences that would preclude use of these alloys in production. They allow for the use of lower Tg printed wire boards materials, which have been shown reliable. These alloys show promise for high reliability applications. In accelerated thermal cycling, all alloys outperformed the circuit boards. Bi precipitation resulted in less degradation to the bulk microstructure. Bi did not impact the IMC formation or growth, a small amount of Ag mitigated growth of Cu3Sn.

  12. Auroral plasma acceleration processes at Mars

    NASA Astrophysics Data System (ADS)

    Lundin, R.; Barabash, S.; Winningham, D.

    2012-09-01

    Following the first Mars Express (MEX) findings of auroral plasma acceleration above Martian magnetic anomalies[1, 2], a more detailed analysis is carried out regarding the physical processes that leads to plasma acceleration, and how they connect to the dynamo-, and energy source regions. The ultimate energy source for Martian plasma acceleration is the solar wind. The question is, by what mechanisms is solar wind energy and momentum transferred into the magnetic flux tubes that connect to Martian magnetic anomalies? What are the key plasma acceleration processes that lead to aurora and the associated ionospheric plasma outflow from Mars? The experimental setup on MEX limits our capability to carry out "auroral physics" at Mars. However, with knowledge acquired from the Earth, we may draw some analogies with terrestrial auroral physics. Using the limited data set available, consisting of primarily ASPERA and MARSIS data, an interesting picture of aurora at Mars emerges. There are some strong similarities between accelerated/heated electrons and ions in the nightside high altitude region above Mars and the electron/ion acceleration above Terrestrial discrete aurora. Nearly monoenergetic downgoing electrons are observed in conjunction with nearly monoenergetic upgoing ions. Monoenergetic counterstreaming ions and electrons is the signature of plasma acceleration in quasi-static electric fields. However, compared to the Earth's aurora, with auroral process guided by a dipole field, aurora at Mars is expected to form complex patterns in the multipole environment governed by the Martian crustal magnetic field regions. Moreover, temporal/spatial scales are different at Mars. It is therefore of interest to mention another common characteristics that exist for Earth and Mars, plasma acceleration by waves. Low-frequency, Alfvén, waves is a very powerful means of plasma acceleration in the Earth's magnetosphere. Low-frequency waves associated with plasma acceleration

  13. Coordination Chemistry of Diiodine and Implications for the Oxidation Capacity of the Synergistic Ag(+) /X2 (X=Cl, Br, I) System.

    PubMed

    Malinowski, Przemysław J; Himmel, Daniel; Krossing, Ingo

    2016-08-01

    The synergistic Ag(+) /X2 system (X=Cl, Br, I) is a very strong, but ill-defined oxidant-more powerful than X2 or Ag(+) alone. Intermediates for its action may include [Agm (X2 )n ](m+) complexes. Here, we report on an unexpectedly variable coordination chemistry of diiodine towards this direction: (A)Ag-I2 -Ag(A), [Ag2 (I2 )4 ](2+) (A(-) )2 and [Ag2 (I2 )6 ](2+) (A(-) )2 ⋅(I2 )x≈0.65 form by reaction of Ag(A) (A=Al(OR(F) )4 ; R(F) =C(CF3 )3 ) with diiodine (single crystal/powder XRD, Raman spectra and quantum-mechanical calculations). The molecular (A)Ag-I2 -Ag(A) is ideally set up to act as a 2 e(-) oxidant with stoichiometric formation of 2 AgI and 2 A(-) . Preliminary reactivity tests proved this (A)Ag-I2 -Ag(A) starting material to oxidize n-C5 H12 , C3 H8 , CH2 Cl2 , P4 or S8 at room temperature. A rough estimate of its electron affinity places it amongst very strong oxidizers like MF6 (M=4d metals). This suggests that (A)Ag-I2 -Ag(A) will serve as an easily in bulk accessible, well-defined, and very potent oxidant with multiple applications.

  14. Scaling FFAG accelerator for muon acceleration

    SciTech Connect

    Lagrange, JB.; Planche, T.; Mori, Y.

    2011-10-06

    Recent developments in scaling fixed field alternating gradient (FFAG) accelerators have opened new ways for lattice design, with straight sections, and insertions like dispersion suppressors. Such principles and matching issues are detailed in this paper. An application of these new concepts is presented to overcome problems in the PRISM project.

  15. Scaling FFAG accelerator for muon acceleration

    NASA Astrophysics Data System (ADS)

    Lagrange, JB.; Planche, T.; Mori, Y.

    2011-10-01

    Recent developments in scaling fixed field alternating gradient (FFAG) accelerators have opened new ways for lattice design, with straight sections, and insertions like dispersion suppressors. Such principles and matching issues are detailed in this paper. An application of these new concepts is presented to overcome problems in the PRISM project.

  16. Angular velocities, angular accelerations, and coriolis accelerations

    NASA Technical Reports Server (NTRS)

    Graybiel, A.

    1975-01-01

    Weightlessness, rotating environment, and mathematical analysis of Coriolis acceleration is described for man's biological effective force environments. Effects on the vestibular system are summarized, including the end organs, functional neurology, and input-output relations. Ground-based studies in preparation for space missions are examined, including functional tests, provocative tests, adaptive capacity tests, simulation studies, and antimotion sickness.

  17. Novel CX⋯π halogen bonds in complexes of acetylene and its derivatives of Na and MPH3 (M=Cu, Ag, Au) with XCCF (X=Cl, Br, I).

    PubMed

    Zhuo, Hongying; Liu, Mingjuan; Li, Qingzhong; Li, Wenzuo; Cheng, Jianbo

    2014-06-05

    Ab initio calculations have been carried out for a variety of model systems with a T-shaped CX⋯π motif. The CX⋯π interaction of acetylene with the halogen donor molecule XCCF (X=Cl, Br, I) is invariably found to be weak with the interaction energy less than 11kJ/mol in magnitude. Substitution of the two protons in acetylene with more electron-donating sodium atoms increases the π electron density in the CC bond and leads to a substantial enhancement in its interaction with the halogen donor. The calculated interaction energies increase to as much as 73kJ/mol in the case of C2Na2-ICCF. The interaction of XCCF with a model coinage metal ethynide, H3PMCCMPH3 (M=Cu, Ag, Au), is intermediate between these two extremes, and the interaction energy is related to the nature of coinage metals. The CX⋯π halogen bonds have been analyzed with natural bond orbital, atoms in molecules, and energy decomposition.

  18. Muon Acceleration Concepts for Future Neutrino Factory

    SciTech Connect

    Bogacz, Slawomir Alex

    2016-05-01

    Here, we summarize current state of concept for muon acceleration aimed at future Neutrino Factory. The main thrust of these studies was to reduce the overall cost while maintaining performance through exploring interplay between complexity of the cooling systems and the acceptance of the accelerator complex. To ensure adequate survival of the short-lived muons, acceleration must occur at high average gradient. The need for large transverse and longitudinal acceptances drives the design of the acceleration system to initially low RF frequency, e.g. 325 MHz, and then increased to 650 MHz, as the transverse size shrinks with increasing energy. High-gradient normal conducting RF cavities at these frequencies require extremely high peak-power RF sources. Hence superconducting RF (SRF) cavities are chosen. Here, we considered two cost effective schemes for accelerating muon beams for a stagable Neutrino Factory: Exploration of the so-called 'dual-use' linac concept, where the same linac structure is used for acceleration of both H- and muons and alternatively, the SRF efficient design based on multi-pass (4.5) 'dogbone' RLA, extendable to multi-pass FFAG-like arcs.

  19. Induction linear accelerators

    NASA Astrophysics Data System (ADS)

    Birx, Daniel

    1992-03-01

    Among the family of particle accelerators, the Induction Linear Accelerator is the best suited for the acceleration of high current electron beams. Because the electromagnetic radiation used to accelerate the electron beam is not stored in the cavities but is supplied by transmission lines during the beam pulse it is possible to utilize very low Q (typically<10) structures and very large beam pipes. This combination increases the beam breakup limited maximum currents to of order kiloamperes. The micropulse lengths of these machines are measured in 10's of nanoseconds and duty factors as high as 10-4 have been achieved. Until recently the major problem with these machines has been associated with the pulse power drive. Beam currents of kiloamperes and accelerating potentials of megavolts require peak power drives of gigawatts since no energy is stored in the structure. The marriage of liner accelerator technology and nonlinear magnetic compressors has produced some unique capabilities. It now appears possible to produce electron beams with average currents measured in amperes, peak currents in kiloamperes and gradients exceeding 1 MeV/meter, with power efficiencies approaching 50%. The nonlinear magnetic compression technology has replaced the spark gap drivers used on earlier accelerators with state-of-the-art all-solid-state SCR commutated compression chains. The reliability of these machines is now approaching 1010 shot MTBF. In the following paper we will briefly review the historical development of induction linear accelerators and then discuss the design considerations.

  20. Accelerator Science: Why RF?

    SciTech Connect

    Lincoln, Don

    2016-12-21

    Particle accelerators can fire beams of subatomic particles at near the speed of light. The accelerating force is generated using radio frequency technology and a whole lot of interesting features. In this video, Fermilab’s Dr. Don Lincoln explains how it all works.

  1. Particle Acceleration in Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi

    2005-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma ray burst (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments.

  2. Accelerators Beyond The Tevatron?

    SciTech Connect

    Lach, Joseph; /Fermilab

    2010-07-01

    Following the successful operation of the Fermilab superconducting accelerator three new higher energy accelerators were planned. They were the UNK in the Soviet Union, the LHC in Europe, and the SSC in the United States. All were expected to start producing physics about 1995. They did not. Why?

  3. Accelerators (3/5)

    ScienceCinema

    None

    2016-07-12

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  4. Diagnostics for induction accelerators

    SciTech Connect

    Fessenden, T.J.

    1996-04-01

    The induction accelerator was conceived by N. C. Christofilos and first realized as the Astron accelerator that operated at LLNL from the early 1960`s to the end of 1975. This accelerator generated electron beams at energies near 6 MeV with typical currents of 600 Amperes in 400 ns pulses. The Advanced Test Accelerator (ATA) built at Livermore`s Site 300 produced 10,000 Ampere beams with pulse widths of 70 ns at energies approaching 50 MeV. Several other electron and ion induction accelerators have been fabricated at LLNL and LBNL. This paper reviews the principal diagnostics developed through efforts by scientists at both laboratories for measuring the current, position, energy, and emittance of beams generated by these high current, short pulse accelerators. Many of these diagnostics are closely related to those developed for other accelerators. However, the very fast and intense current pulses often require special diagnostic techniques and considerations. The physics and design of the more unique diagnostics developed for electron induction accelerators are presented and discussed in detail.

  5. Accelerators (4/5)

    ScienceCinema

    None

    2016-07-12

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  6. Measuring Model Rocket Acceleration.

    ERIC Educational Resources Information Center

    Jenkins, Randy A.

    1993-01-01

    Presents an experiment that measures the acceleration and velocity of a model rocket. Lift-off information is transmitted to a computer that creates a graph of the velocity. Discusses the analysis of the computer-generated data and differences between calculated and experimental velocity and acceleration of several rocket types. (MDH)

  7. Microscale acceleration history discriminators

    DOEpatents

    Polosky, Marc A.; Plummer, David W.

    2002-01-01

    A new class of micromechanical acceleration history discriminators is claimed. These discriminators allow the precise differentiation of a wide range of acceleration-time histories, thereby allowing adaptive events to be triggered in response to the severity (or lack thereof) of an external environment. Such devices have applications in airbag activation, and other safety and surety applications.

  8. Accelerators (5/5)

    ScienceCinema

    None

    2016-07-12

    1a) Introduction and motivation 1b) History and accelerator types 2) Transverse beam dynamics 3a) Longitudinal beam dynamics 3b) Figure of merit of a synchrotron/collider 3c) Beam control 4) Main limiting factors 5) Technical challenges Prerequisite knowledge: Previous knowledge of accelerators is not required.

  9. Accelerators Beyond The Tevatron?

    SciTech Connect

    Lach, Joseph

    2010-07-29

    Following the successful operation of the Fermilab superconducting accelerator three new higher energy accelerators were planned. They were the UNK in the Soviet Union, the LHC in Europe, and the SSC in the United States. All were expected to start producing physics about 1995. They did not. Why?.

  10. Modification of a novel angiogenic peptide, AG30, for the development of novel therapeutic agents.

    PubMed

    Nakagami, Hironori; Nishikawa, Tomoyuki; Tamura, Nao; Maeda, Akito; Hibino, Hajime; Mochizuki, Masayoshi; Shimosato, Takashi; Moriya, Toshinori; Morishita, Ryuichi; Tamai, Katsuto; Tomono, Kazunori; Kaneda, Yasufumi

    2012-07-01

    We previously identified a novel angiogenic peptide, AG30, with antibacterial effects that could serve as a foundation molecule for the design of wound-healing drugs. Toward clinical application, in this study we have developed a modified version of the AG30 peptide characterized by improved antibacterial and angiogenic action, thus establishing a lead compound for a feasibility study. Because AG30 has an α-helix structure with a number of hydrophobic and cationic amino acids, we designed a modified AG30 peptide by replacing several of the amino acids. The replacement of cationic amino acids (yielding a new molecule, AG30/5C), but not hydrophobic amino acids, increased both the angiogenic and the antimicrobial properties of the peptide. AG30/5C was also effective against methicillin-resistant Staphylococcus aureus (MRSA) and antibiotic-resistant Pseudomonas aeruginosa. In a diabetic mouse wound-healing model, the topical application of AG30/5C accelerated wound healing with increased angiogenesis and attenuated MRSA infection. To facilitate the eventual clinical investigation/application of these compounds, we developed a large-scale procedure for the synthesis of AG30/5C that employed the conventional solution method and met Good Manufacturing Practice guidelines. In the evaluation of stability of this peptide in saline solution, RP-HPLC analysis revealed that AG30/5C was fairly stable under 5°C for 12 months. Therefore, we propose the use of AG30/5C as a wound-healing drug with antibacterial and angiogenic actions.

  11. Accelerators, Beams And Physical Review Special Topics - Accelerators And Beams

    SciTech Connect

    Siemann, R.H.; /SLAC

    2011-10-24

    Accelerator science and technology have evolved as accelerators became larger and important to a broad range of science. Physical Review Special Topics - Accelerators and Beams was established to serve the accelerator community as a timely, widely circulated, international journal covering the full breadth of accelerators and beams. The history of the journal and the innovations associated with it are reviewed.

  12. Theoretical study of silver-ion-mediated base pairs: the case of C-Ag-C and C-Ag-A systems.

    PubMed

    Fortino, Mariagrazia; Marino, Tiziana; Russo, Nino

    2015-05-28

    Silver-mediated base pairs applied to DNA represent a new biomacromolecular nanomaterial useful for generating nanodevices as ion sensors. Reported herein is a full quantum chemical study devoted to give further knowledge on the electronic and energetic properties of C-Ag-C and mixed C-Ag-A mismatched base pairs. The B3LYP functional in conjunction with the dispersion effects (D3) has been applied. Single-point calculations have been also performed by using the M06-L functional. The investigation of their behavior has been extended to the duplex DNA modeled by the (dC-Ag-dC)2 and (dC-Ag-dA)2 more complex systems. The solvent effect has been taken into account by the conductor-like screening model, COSMO. In the case of mixed C-Ag-A and (dC-Ag-dA)2 systems, both the Watson-Crick and Hoogsteen arrangements have been taken into account. Results show that for (dC-Ag-dA)2 systems, the binding energies are almost double that of the corresponding values of C-Ag-A ones.

  13. Regulation of Chemokine Signal Integration by Activator of G-Protein Signaling 4 (AGS4)

    PubMed Central

    Robichaux, William G.; Branham-O’Connor, Melissa; Hwang, Il-Young; Vural, Ali; Kehrl, Johne H.

    2017-01-01

    Activator of G-protein signaling 4 (AGS4)/G-protein signaling modulator 3 (Gpsm3) contains three G-protein regulatory (GPR) motifs, each of which can bind Gαi-GDP free of Gβγ. We previously demonstrated that the AGS4-Gαi interaction is regulated by seven transmembrane-spanning receptors (7-TMR), which may reflect direct coupling of the GPR-Gαi module to the receptor analogous to canonical Gαβγ heterotrimer. We have demonstrated that the AGS4-Gαi complex is regulated by chemokine receptors in an agonist-dependent manner that is receptor-proximal. As an initial approach to investigate the functional role(s) of this regulated interaction in vivo, we analyzed leukocytes, in which AGS4/Gpsm3 is predominantly expressed, from AGS4/Gpsm3-null mice. Loss of AGS4/Gpsm3 resulted in mild but significant neutropenia and leukocytosis. Dendritic cells, T lymphocytes, and neutrophils from AGS4/Gpsm3-null mice also exhibited significant defects in chemoattractant-directed chemotaxis and extracellular signal-regulated kinase activation. An in vivo peritonitis model revealed a dramatic reduction in the ability of AGS4/Gpsm3-null neutrophils to migrate to primary sites of inflammation. Taken together, these data suggest that AGS4/Gpsm3 is required for proper chemokine signal processing in leukocytes and provide further evidence for the importance of the GPR-Gαi module in the regulation of leukocyte function. PMID:28062526

  14. Particle Acceleration and Emission in Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.; Hardee, P. E.; Richardson, G. A.; Preece, R. D.; Sol, H.; Fishman, G. J.

    2003-01-01

    Shock wave acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. While some Fermi acceleration may occur at the jet front, the majority of electron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  15. Growth of Ag nanoparticles using plasma-modified multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tseng, Chun-Hao; Chen, Chuh-Yung

    2008-01-01

    This study presents a novel method for preparing multi-walled carbon nanotubes (MWNTs) grafted with a poly(2-hydroxyethyl methacrylate) (HEMA)-silver complex (CNTs-HEMA-Ag complex) through plasma-induced grafting polymerization. The characteristics of the MWNTs after being grafted with HEMA polymer are monitored by Fourier transform infrared (FT-IR) spectroscopy. The chelating groups in the HEMA polymer grafted on the surface of the CNTs-HEMA are the coordination sites for chelating silver ions, and are further used as nanotemplates for the growing of Ag nanoparticles (quantum dots). Transmission electron microscopy (TEM) reveals that the particle size of Ag nanoparticles on the CNT surfaces increases with the Ag+ chelating concentration, reaction time, and reaction temperature. Moreover, the crystalline phase of Ag nanoparticles is identified by using x-ray diffraction (XRD). In addition, high-resolution x-ray photoelectron spectroscopy (XPS) is used to characterize the functional groups on the surface of the MWNTs after chemical modification through plasma treatment; it demonstrates that the growing amount of the Ag nanoparticles on the nanotubes increases with the Ag+ chelating concentration due to the blocking effect of the Ag particles forming on the MWNTs.

  16. Obtaining the solid-liquid interfacial free energy via multi-scheme thermodynamic integration: Ag-ethylene glycol interfaces

    NASA Astrophysics Data System (ADS)

    Qi, Xin; Zhou, Ya; Fichthorn, Kristen A.

    2016-11-01

    The solid-liquid interfacial free energy γs l is an important quantity in wetting, nucleation, and crystal growth. Although various methods have been developed to calculate γs l with atomic-scale simulations, such calculations still remain challenging for multi-component interfaces between molecular fluids and solids. We present a multi-scheme thermodynamic integration method that is inspired by the "cleaving-wall" method and aimed at obtaining γs l for such systems using open-source simulation packages. This method advances two aspects of its predecessor methods. First, we incorporate separate schemes to resolve difficulties when manipulating periodic boundary conditions of the supercell using open-source simulation packages. Second, we introduce a numerical approximation to obtain thermodynamic integrands for complex force fields when an analytical differentiation is not readily available. To demonstrate this method, we obtain γs l for interfaces between Ag(100) and Ag(111) and ethylene glycol (EG). These interfacial free energies mirror interfacial potential energies for each facet. We also estimate entropies of interface formation and these are consistent with theoretical predictions in signs and trends. For the Ag-EG systems, we find that the largest contribution to γs l is the free energy to create the bare metal surfaces. The second-largest contribution to γs l is from the liquid-solid interaction. This user-friendly method will accelerate investigation in a broad range of research topics, such as the thermodynamic effect of structure-directing agents in solution-phase shape-controlled nanocrystal syntheses.

  17. Radiation Safety Systems for Accelerator Facilities

    SciTech Connect

    Liu, James C

    2001-10-17

    The Radiation Safety System (RSS) of an accelerator facility is used to protect people from prompt radiation hazards associated with accelerator operation. The RSS is a fully interlocked, engineered system with a combination of passive and active elements that are reliable, redundant, and fail-safe. The RSS consists of the Access Control System (ACS) and the Radiation Containment System (RCS). The ACS is to keep people away from the dangerous radiation inside the shielding enclosure. The RCS limits and contains the beam/radiation conditions to protect people from the prompt radiation hazards outside the shielding enclosure in both normal and abnormal operations. The complexity of a RSS depends on the accelerator and its operation, as well as associated hazard conditions. The approaches of RSS among different facilities can be different. This report gives a review of the RSS for accelerator facilities.

  18. Radiation Safety Systems for Accelerator Facilities

    SciTech Connect

    James C. Liu; Jeffrey S. Bull; John Drozdoff; Robert May; Vaclav Vylet

    2001-10-01

    The Radiation Safety System (RSS) of an accelerator facility is used to protect people from prompt radiation hazards associated with accelerator operation. The RSS is a fully interlocked, engineered system with a combination of passive and active elements that are reliable, redundant, and fail-safe. The RSS consists of the Access Control System (ACS) and the Radiation Containment System (RCS). The ACS is to keep people away from the dangerous radiation inside the shielding enclosure. The RCS limits and contains the beam/radiation conditions to protect people from the prompt radiation hazards outside the shielding enclosure in both normal and abnormal operations. The complexity of a RSS depends on the accelerator and its operation, as well as associated hazard conditions. The approaches of RSS among different facilities can be different. This report gives a review of the RSS for accelerator facilities.

  19. Measurement of Coriolis Acceleration with a Smartphone

    NASA Astrophysics Data System (ADS)

    Shakur, Asif; Kraft, Jakob

    2016-05-01

    Undergraduate physics laboratories seldom have experiments that measure the Coriolis acceleration. This has traditionally been the case owing to the inherent complexities of making such measurements. Articles on the experimental determination of the Coriolis acceleration are few and far between in the physics literature. However, because modern smartphones come with a raft of built-in sensors, we have a unique opportunity to experimentally determine the Coriolis acceleration conveniently in a pedagogically enlightening environment at modest cost by using student-owned smartphones. Here we employ the gyroscope and accelerometer in a smartphone to verify the dependence of Coriolis acceleration on the angular velocity of a rotatingtrack and the speed of the sliding smartphone.

  20. Radially dependent angular acceleration of twisted light.

    PubMed

    Webster, Jason; Rosales-Guzmán, Carmelo; Forbes, Andrew

    2017-02-15

    While photons travel in a straight line at constant velocity in free space, the intensity profile of structured light may be tailored for acceleration in any degree of freedom. Here we propose a simple approach to control the angular acceleration of light. Using Laguerre-Gaussian modes as our twisted beams carrying orbital angular momentum, we show that superpositions of opposite handedness result in a radially dependent angular acceleration as they pass through a focus (waist plane). Due to conservation of orbital angular momentum, we find that propagation dynamics are complex despite the free-space medium: the outer part of the beam (rings) rotates in an opposite direction to the inner part (petals), and while the outer part accelerates, the inner part decelerates. We outline the concepts theoretically and confirm them experimentally. Such exotic structured light beams are topical due to their many applications, for instance in optical trapping and tweezing, metrology, and fundamental studies in optics.

  1. Accurate measurement of silver isotopic compositions in geological materials including low Pd/Ag meteorites

    NASA Astrophysics Data System (ADS)

    Woodland, S. J.; Rehkämper, M.; Halliday, A. N.; Lee, D.-C.; Hattendorf, B.; Günther, D.

    2005-04-01

    Very precise silver (Ag) isotopic compositions have been determined for a number of terrestrial rocks, and high and low Pd/Ag meteorites by utilizing multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The meteorites include primitive chondrites, the Group IAB iron meteorites Canyon Diablo and Toluca, and the Group IIIAB iron meteorite Grant. Silver isotopic measurements are primarily of interest because 107Ag was produced by decay of the short-lived radionuclide 107Pd during the formation of the solar system and hence the Pd-Ag chronometer has set constraints on the timing of early planetesimal formation. A 2σ precision of ±0.05‰ can be obtained for analyses of standard solutions when Ag isotopic ratios are normalized to Pd, to correct for instrumental mass discrimination, and to bracketing standards. Caution must be exercised when making Ag isotopic measurements because isotopic artifacts can be generated in the laboratory and during mass spectrometry. The external reproducibility for geological samples based on replicate analyses of rocks is ±0.2‰ (2σ). All chondrites analyzed have similar Ag isotopic compositions that do not differ significantly (>0.3‰) from the 'terrestrial' value of the NIST SRM 978a Ag isotope standard. Hence, they show no evidence of excess 107Ag derived from 107Pd decay or, of stable Ag isotope fractionation associated with volatile element depletion within the accretion disk or from parent body metamorphism. The Group IAB iron meteorite samples analyzed show evidence of complex behavior and disturbance of Ag isotope systematics. Therefore, care must be taken when using this group of iron meteorites to obtain chronological information based on the Pd-Ag decay scheme.

  2. Ice nucleation efficiency of AgI: review and new insights

    NASA Astrophysics Data System (ADS)

    Marcolli, Claudia; Nagare, Baban; Welti, André; Lohmann, Ulrike

    2016-07-01

    AgI is one of the best-investigated ice-nucleating substances. It has relevance for the atmosphere since it is used for glaciogenic cloud seeding. Theoretical and experimental studies over the last 60 years provide a complex picture of silver iodide as an ice-nucleating agent with conflicting and inconsistent results. This review compares experimental ice nucleation studies in order to analyze the factors that influence the ice nucleation ability of AgI. The following picture emerges from this analysis: the ice nucleation ability of AgI seems to be enhanced when the AgI particle is on the surface of a droplet, which is indeed the position that a particle takes when it can freely move in a droplet. The ice nucleation by particles with surfaces exposed to air depends on water adsorption. AgI surfaces seem to be most efficient at nucleating ice when they are exposed to relative humidity at or even above water saturation. For AgI particles that are completely immersed in water, the freezing temperature increases with increasing AgI surface area. Higher threshold freezing temperatures seem to correlate with improved lattice matches as can be seen for AgI-AgCl solid solutions and 3AgI·NH4I·6H2O, which have slightly better lattice matches with ice than AgI and also higher threshold freezing temperatures. However, the effect of a good lattice match is annihilated when the surfaces have charges. Also, the ice nucleation ability seems to decrease during dissolution of AgI particles. This introduces an additional history and time dependence for ice nucleation in cloud chambers with short residence times.

  3. The Catalytic Behaviour of NanoAg@montmorillonite Composite Materials

    NASA Astrophysics Data System (ADS)

    Karlíková, Martina; Kvítek, Libor; Prucek, Robert; Panáček, Aleš; Filip, Jan; Pechoušek, Jiří; Adegboyega, Nathaniel F.

    The preparation of nanoAg@montmorillonite composite materials and their catalytic activity is reported in this article. The nanoAg@montmorillonite composite materials were prepared by the adsorption of silver NPs, with an average size about 30 nm, from their aqueous dispersion onto two types of montmorillonite with different chemical composition. Silver NPs were prepared via modified Tollens process, which involves the reduction of [Ag(NH3)2]+ complex cation by maltose. The amount of silver NPs anchored onto the MMT surfaces was determined by UV-VIS spectroscopy; the decrease in absorbance of the dispersion after the adsorption was monitored. Prepared nanocomposite materials were subsequently characterized by means of transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). The reduction of 4-nitrophenol by sodium borohydride was chosen to examine the catalytic properties of the synthesized silver nanocomposite materials.

  4. 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:

  5. Inputs, dynamics and potential impacts of silver (Ag) from urban wastewater to a highly turbid estuary (SW France).

    PubMed

    Deycard, Victoria N; Schäfer, Jörg; Petit, Jérôme C J; Coynel, Alexandra; Lanceleur, Laurent; Dutruch, Lionel; Bossy, Cécile; Ventura, Alexandre; Blanc, Gérard

    2017-01-01

    Although silver (Ag) has been listed as a priority pollutant for the aquatic environment by the European Union (Directive 2006/11/EC), the use of Ag-based products with antimicrobial effects is increasing in Europe, as well as North America and Asia. This study investigates personal care products (PCP) as a potential source of Ag in wastewater, as well as the dynamics and fate of Ag in the influent and effluent of a major urban wastewater treatment plant (WWTP) located on the fluvial part of the Gironde Estuary. Typical household PCPs marked as using Ag contained concentrations of up to 0.4 mg kg(-1) making them likely contributors to urban Ag released into the aquatic environment. Silver concentrations in influent wastewater generally occurred during mid-week working hours and decreased during the night and on weekends clearly indicating the dominance of urban sources. Up to 90% of the total Ag in wastewater was bound to particles and efficiently (>80%) removed by the treatment process, whereas 20% of Ag was released into the fluvial estuary. Silver concentrations in wastewater effluents clearly exceeded estuarine concentrations and may strongly amplify the local Ag concentrations and fluxes, especially during summer rainstorms in low river discharge conditions. Further work should focus on environmental effects and fate of urban Ag release due to immediate localized outfall and/or the adsorption on estuarine particles and subsequent release as dissolved Ag chloro-complexes within the estuarine salinity gradient.

  6. An AgI@g-C3N4 hybrid core@shell structure: Stable and enhanced photocatalytic degradation

    NASA Astrophysics Data System (ADS)

    Liu, Li; Qi, Yuehong; Yang, Jinyi; Cui, Wenquan; Li, Xingang; Zhang, Zisheng

    2015-12-01

    A novel visible-light-active material AgI@g-C3N4 was prepared by ultrasonication/chemisorption method. The core@shell structure AgI@g-C3N4 catalyst showed high efficiency for the degradation of MB under visible light irradiation (λ > 420 nm). Nearly 96.5% of MB was degraded after 120 min of irradiation in the presence of the AgI@g-C3N4 photocatalyst. Superior stability was also observed in the cyclic runs indicating that the as prepared hybrid composite is highly desirable for the remediation of organic contaminated wastewaters. The improved photocatalytic performance is due to synergistic effects at the interface of AgI and g-C3N4 which can effectively accelerate the charge separation and reinforce the photostability of hybrid composite. The possible mechanism for the photocatalytic activity of AgI@g-C3N4 was tentatively proposed.

  7. The Silver Complexes of Porphyrins, Corroles, and Carbaporphyrins: Silver in the Oxidation States II and III

    ERIC Educational Resources Information Center

    Bruckner, Christian

    2004-01-01

    Studies in relation to the silver complexes of porphyrins, corroles and carbaporphyrins are presented especially with relation to silver in the oxidation states II and III. It is seen that the Ag(sub III) complex was electrochemically readily and reversibly reduced to the corresponding Ag(sub II) complex, thus indicating that the complex could be…

  8. Large electrostatic accelerators

    SciTech Connect

    Jones, C.M.

    1984-01-01

    The increasing importance of energetic heavy ion beams in the study of atomic physics, nuclear physics, and materials science has partially or wholly motivated the construction of a new generation of large electrostatic accelerators designed to operate at terminal potentials of 20 MV or above. In this paper, the author briefly discusses the status of these new accelerators and also discusses several recent technological advances which may be expected to further improve their performance. The paper is divided into four parts: (1) a discussion of the motivation for the construction of large electrostatic accelerators, (2) a description and discussion of several large electrostatic accelerators which have been recently completed or are under construction, (3) a description of several recent innovations which may be expected to improve the performance of large electrostatic accelerators in the future, and (4) a description of an innovative new large electrostatic accelerator whose construction is scheduled to begin next year. Due to time and space constraints, discussion is restricted to consideration of only tandem accelerators.

  9. Thickness-dependent spontaneous dewetting morphology of ultrathin Ag films.

    PubMed

    Krishna, H; Sachan, R; Strader, J; Favazza, C; Khenner, M; Kalyanaraman, R

    2010-04-16

    We show here that the morphological pathway of spontaneous dewetting of ultrathin Ag films on SiO2 under nanosecond laser melting is dependent on film thickness. For films with thickness h of 2 nm < or = h < or = 9.5 nm, the morphology during the intermediate stages of dewetting consisted of bicontinuous structures. For films with 11.5 nm < or = h < or = 20 nm, the intermediate stages consisted of regularly sized holes. Measurement of the characteristic length scales for different stages of dewetting as a function of film thickness showed a systematic increase, which is consistent with the spinodal dewetting instability over the entire thickness range investigated. This change in morphology with thickness is consistent with observations made previously for polymer films (Sharma and Khanna 1998 Phys. Rev. Lett. 81 3463-6; Seemann et al 2001 J. Phys.: Condens. Matter 13 4925-38). Based on the behavior of free energy curvature that incorporates intermolecular forces, we have estimated the morphological transition thickness for the intermolecular forces for Ag on SiO2. The theory predictions agree well with observations for Ag. These results show that it is possible to form a variety of complex Ag nanomorphologies in a consistent manner, which could be useful in optical applications of Ag surfaces, such as in surface enhanced Raman sensing.

  10. 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.

  11. 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.

  12. Accelerated testing of space mechanisms

    NASA Technical Reports Server (NTRS)

    Murray, S. Frank; Heshmat, Hooshang

    1995-01-01

    This report contains a review of various existing life prediction techniques used for a wide range of space mechanisms. Life prediction techniques utilized in other non-space fields such as turbine engine design are also reviewed for applicability to many space mechanism issues. The development of new concepts on how various tribological processes are involved in the life of the complex mechanisms used for space applications are examined. A 'roadmap' for the complete implementation of a tribological prediction approach for complex mechanical systems including standard procedures for test planning, analytical models for life prediction and experimental verification of the life prediction and accelerated testing techniques are discussed. A plan is presented to demonstrate a method for predicting the life and/or performance of a selected space mechanism mechanical component.

  13. The synthesis and characterization of Ag-N dual-doped p-type ZnO: experiment and theory.

    PubMed

    Duan, Li; Wang, Pei; Yu, Xiaochen; Han, Xiao; Chen, Yongnan; Zhao, Peng; Li, Donglin; Yao, Ran

    2014-03-07

    Ag-N dual-doped ZnO films have been fabricated by a chemical bath deposition method. The p-type conductivity of the dual-doped ZnO:(Ag, N) is stable over a long period of time, and the hole concentration in the ZnO:(Ag, N) is much higher than that in mono-doped ZnO:Ag or ZnO:N. We found that this is because AgZn-NO complex acceptors can be formed in ZnO:(Ag, N). First-principles calculations show that the complex acceptors generate a fully occupied band above the valance band maximum, so the acceptor levels become shallower and the hole concentration is increased. Furthermore, the binding energy of the Ag-N complex in ZnO is negative, so ZnO:(Ag, N) can be stable. These results indicate that the Ag-N dual-doping may be expected to be a potential route to achieving high-quality p-type ZnO for use in a variety of devices.

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

    PubMed Central

    2013-01-01

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

  15. Vacuum Beat Wave Accelerator

    NASA Astrophysics Data System (ADS)

    Moore, C. I.; Hafizi, B.; Ting, A.; Burris, H. R.; Sprangle, P.; Esarey, E.; Ganguly, A.; Hirshfield, J. L.

    1997-11-01

    The Vacuum Beat Wave Accelerator (VBWA) is a particle acceleration scheme which uses the non-linear ponderomotive beating of two different frequency laser beams to accelerate electrons. A proof-of-principle experiment to demonstrate the VBWA is underway at the Naval Research Laboratory (NRL). This experiment will use the beating of a 1054 nm and 527 nm laser pulse from the NRL T-cubed laser to generate the beat wave and a 4.5 MeV RF electron gun as the electron source. Simulation results and the experimental design will be presented. The suitability of using axicon or higher order Gaussian laser beams will also be discussed.

  16. Ion beam accelerator system

    NASA Technical Reports Server (NTRS)

    Aston, Graeme (Inventor)

    1984-01-01

    A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids (16, 18) with multiple pairs of aligned holes positioned to direct a group of beamlets (20) along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam (14). An accelerator electrode device (22) downstream from the extraction grids, is at a much lower potential than the grids to accelerate the combined beam.

  17. Ion beam accelerator system

    NASA Technical Reports Server (NTRS)

    Aston, G. (Inventor)

    1981-01-01

    A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids with multiple pairs of aligned holes positioned to direct a group of beamlets along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam. An accelerator electrode device downstream from the extraction grids is at a much lower potential than the grids to accelerate the combined beam. The application of the system to ion implantation is mentioned.

  18. STATUS AND RECENT PERFORMANCE OF THE ACCELERATORS THAT SERVE AS GOLD INJECTOR FOR RHIC.

    SciTech Connect

    AHRENS,L.; ALESSI,J.; VAN ASSELT,W.; BENJAMIN,J.; BLASKIEWICZ,M.; BRENNAN,J.M.; BROWN,K.A.; CARLSON,C.; DELONG,J.; GARDNER,C.J.; GLENN,J.W.; HAYES,T.; ROSER,T.; SMITH,K.S.; STESKI,D.; TSOUPAS,N.; ZENO,K.; ZHANG,S.Y.

    2001-06-18

    The recent successful commissioning and operation [1] of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) requires the injection of gold ions of specified energy and intensity with longitudinal and transverse emittances small enough to meet the luminosity requirements of the collider. Ion beams with the desired characteristics are provided by a series of three accelerators, the Tandem, Booster and AGS. The current status and recent performance of these accelerators are reviewed in this paper.

  19. Compact RF ion source for industrial electrostatic ion accelerator

    SciTech Connect

    Kwon, Hyeok-Jung Park, Sae-Hoon; Kim, Dae-Il; Cho, Yong-Sub

    2016-02-15

    Korea Multi-purpose Accelerator Complex is developing a single-ended electrostatic ion accelerator to irradiate gaseous ions, such as hydrogen and nitrogen, on materials for industrial applications. ELV type high voltage power supply has been selected. Because of the limited space, electrical power, and robust operation, a 200 MHz RF ion source has been developed. In this paper, the accelerator system, test stand of the ion source, and its test results are described.

  20. Effect of tyrphostin AG879 on Kv4.2 and Kv4.3 potassium channels

    PubMed Central

    Yu, Haibo; Zou, Beiyan; Wang, Xiaoliang; Li, Min

    2015-01-01

    Background and Purpose A-type potassium channels (IA) are important proteins for modulating neuronal membrane excitability. The expression and activity of Kv4.2 channels are critical for neurological functions and pharmacological inhibitors of Kv4.2 channels may have therapeutic potential for Fragile X syndrome. While screening various compounds, we identified tyrphostin AG879, a tyrosine kinase inhibitor, as a Kv4.2 inhibitor from. In the present study we characterized the effect of AG879 on cloned Kv4.2/Kv channel-interacting protein 2 (KChIP2) channels. Experimental Approach To screen the library of pharmacologically active compounds, the thallium flux assay was performed on HEK-293 cells transiently-transfected with Kv4.2 cDNA using the Maxcyte transfection system. The effects of AG879 were further examined on CHO-K1 cells expressing Kv4.2/KChIP2 channels using a whole-cell patch-clamp technique. Key Results Tyrphostin AG879 selectively and dose-dependently inhibited Kv4.2 and Kv4.3 channels. In Kv4.2/KChIP2 channels, AG879 induced prominent acceleration of the inactivation rate, use-dependent block and slowed the recovery from inactivation. AG879 induced a hyperpolarizing shift in the voltage-dependence of the steady-state inactivation of Kv4.2 channels without apparent effect on the V1/2 of the voltage-dependent activation. The blocking effect of AG879 was enhanced as channel inactivation increased. Furthermore, AG879 significantly inhibited the A-type potassium currents in the cultured hippocampus neurons. Conclusion and Implications AG879 was identified as a selective and potent inhibitor the Kv4.2 channel. AG879 inhibited Kv4.2 channels by preferentially interacting with the open state and further accelerating their inactivation. PMID:25752739

  1. 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.

  2. On the high intensity aspects of AGS Booster proton operation

    SciTech Connect

    Reece, R.K.; Ahrens, L.A.; Bleser, E.J.; Brennan, J.M.; Gardner, C.; Glenn, J.W.; Roser, T.; Shoji, Y.; van Asselt, W.; Weng, W.T.

    1993-01-01

    Observations of high intensity effects on the proton performance of the AGS Booster are presented, including present operational limits and correction methods. The transverse emittances, optimum tune working points, damping of coherent transverse oscillations and correction of stopband resonances through third-order are discussed in addition to the observed tune spread due to space charge forces. The initial longitudinal phase space distribution, capture and acceleration parameters and measurements are also given. Operational tools and strategies relevant to the high intensity setup are mentioned.

  3. On the high intensity aspects of AGS Booster proton operation

    SciTech Connect

    Reece, R.K.; Ahrens, L.A.; Bleser, E.J.; Brennan, J.M.; Gardner, C.; Glenn, J.W.; Roser, T.; Shoji, Y.; van Asselt, W.; Weng, W.T.

    1993-06-01

    Observations of high intensity effects on the proton performance of the AGS Booster are presented, including present operational limits and correction methods. The transverse emittances, optimum tune working points, damping of coherent transverse oscillations and correction of stopband resonances through third-order are discussed in addition to the observed tune spread due to space charge forces. The initial longitudinal phase space distribution, capture and acceleration parameters and measurements are also given. Operational tools and strategies relevant to the high intensity setup are mentioned.

  4. CLASHING BEAM PARTICLE ACCELERATOR

    DOEpatents

    Burleigh, R.J.

    1961-04-11

    A charged-particle accelerator of the proton synchrotron class having means for simultaneously accelerating two separate contra-rotating particle beams within a single annular magnet structure is reported. The magnet provides two concentric circular field regions of opposite magnetic polarity with one field region being of slightly less diameter than the other. The accelerator includes a deflector means straddling the two particle orbits and acting to collide the two particle beams after each has been accelerated to a desired energy. The deflector has the further property of returning particles which do not undergo collision to the regular orbits whereby the particles recirculate with the possibility of colliding upon subsequent passages through the deflector.

  5. Vibration control in accelerators

    SciTech Connect

    Montag, C.

    2011-01-01

    In the vast majority of accelerator applications, ground vibration amplitudes are well below tolerable magnet jitter amplitudes. In these cases, it is necessary and sufficient to design a rigid magnet support structure that does not amplify ground vibration. Since accelerator beam lines are typically installed at an elevation of 1-2m above ground level, special care has to be taken in order to avoid designing a support structure that acts like an inverted pendulum with a low resonance frequency, resulting in untolerable lateral vibration amplitudes of the accelerator components when excited by either ambient ground motion or vibration sources within the accelerator itself, such as cooling water pumps or helium flow in superconducting magnets. In cases where ground motion amplitudes already exceed the required jiter tolerances, for instance in future linear colliders, passive vibration damping or active stabilization may be considered.

  6. Dielectric assist accelerating structure

    NASA Astrophysics Data System (ADS)

    Satoh, D.; Yoshida, M.; Hayashizaki, N.

    2016-01-01

    A higher-order TM02 n mode accelerating structure is proposed based on a novel concept of dielectric loaded rf cavities. This accelerating structure consists of ultralow-loss dielectric cylinders and disks with irises which are periodically arranged in a metallic enclosure. Unlike conventional dielectric loaded accelerating structures, most of the rf power is stored in the vacuum space near the beam axis, leading to a significant reduction of the wall loss, much lower than that of conventional normal-conducting linac structures. This allows us to realize an extremely high quality factor and a very high shunt impedance at room temperature. A simulation of a 5 cell prototype design with an existing alumina ceramic indicates an unloaded quality factor of the accelerating mode over 120 000 and a shunt impedance exceeding 650 M Ω /m at room temperature.

  7. Wake field acceleration experiments

    SciTech Connect

    Simpson, J.D.

    1988-01-01

    Where and how will wake field acceleration devices find use for other than, possibly, accelerators for high energy physics. I don't know that this can be responsibly answered at this time. What I can do is describe some recent results from an ongoing experimental program at Argonne which support the idea that wake field techniques and devices are potentially important for future accelerators. Perhaps this will spawn expanded interest and even new ideas for the use of this new technology. The Argonne program, and in particular the Advanced Accelerator Test Facility (AATF), has been reported in several fairly recent papers and reports. But because this is a substantially new audience for the subject, I will include a brief review of the program and the facility before describing experiments. 10 refs., 7 figs.

  8. Accelerator on a Chip

    SciTech Connect

    England, Joel

    2014-06-30

    SLAC's Joel England explains how the same fabrication techniques used for silicon computer microchips allowed their team to create the new laser-driven particle accelerator chips. (SLAC Multimedia Communications)

  9. Charged particle accelerator grating

    DOEpatents

    Palmer, R.B.

    1985-09-09

    A readily disposable and replaceable accelerator grating for a relativistic particle accelerator is described. The grating is formed for a plurality of liquid droplets that are directed in precisely positioned jet streams to periodically dispose rows of droplets along the borders of a predetermined particle beam path. A plurality of lasers are used to direct laser beams onto the droplets, at predetermined angles, thereby to excite the droplets to support electromagnetic accelerating resonances on their surfaces. Those resonances operate to accelerate and focus particles moving along the beam path. As the droplets are distorted or destroyed by the incoming radiation, they are replaced at a predetermined frequency by other droplets supplied through the jet streams.

  10. HEAVY ION LINEAR ACCELERATOR

    DOEpatents

    Van Atta, C.M.; Beringer, R.; Smith, L.

    1959-01-01

    A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.

  11. Principles of Induction Accelerators

    NASA Astrophysics Data System (ADS)

    Briggs*, Richard J.

    The basic concepts involved in induction accelerators are introduced in this chapter. The objective is to provide a foundation for the more detailed coverage of key technology elements and specific applications in the following chapters. A wide variety of induction accelerators are discussed in the following chapters, from the high current linear electron accelerator configurations that have been the main focus of the original developments, to circular configurations like the ion synchrotrons that are the subject of more recent research. The main focus in the present chapter is on the induction module containing the magnetic core that plays the role of a transformer in coupling the pulsed power from the modulator to the charged particle beam. This is the essential common element in all these induction accelerators, and an understanding of the basic processes involved in its operation is the main objective of this chapter. (See [1] for a useful and complementary presentation of the basic principles in induction linacs.)

  12. Accelerator on a Chip

    ScienceCinema

    England, Joel

    2016-07-12

    SLAC's Joel England explains how the same fabrication techniques used for silicon computer microchips allowed their team to create the new laser-driven particle accelerator chips. (SLAC Multimedia Communications)

  13. DIELECTRIC WALL ACCELERATOR TECHNOLOGY

    SciTech Connect

    Sampayan, S; Caporaso, G; Chen, Y; Harris, J; Hawkins, S; Holmes, C; Nelson, S; Poole, B; Rhodes, M; Sanders, D; Sullivan, J; Wang, L; Watson, J

    2007-10-18

    The dielectric wall accelerator (DWA) is a compact pulsed power device where the pulse forming lines, switching, and vacuum wall are integrated into a single compact geometry. For this effort, we initiated a extensive compact pulsed power development program and have pursued the study of switching (gas, oil, laser induced surface flashover and photoconductive), dielectrics (ceramics and nanoparticle composites), pulse forming line topologies (asymmetric and symmetric Blumleins and zero integral pulse forming lines), and multilayered vacuum insulator (HGI) technology. Finally, we fabricated an accelerator cell for test on ETAII (a 5.5 MeV, 2 kA, 70 ns pulsewidth electron beam accelerator). We review our past results and report on the progress of accelerator cell testing.

  14. Amps particle accelerator definition study

    NASA Technical Reports Server (NTRS)

    Sellen, J. M., Jr.

    1975-01-01

    The Particle Accelerator System of the AMPS (Atmospheric, Magnetospheric, and Plasmas in Space) payload is a series of charged particle accelerators to be flown with the Space Transportation System Shuttle on Spacelab missions. In the configuration presented, the total particle accelerator system consists of an energetic electron beam, an energetic ion accelerator, and both low voltage and high voltage plasma acceleration devices. The Orbiter is illustrated with such a particle accelerator system.

  15. Designing reliability into accelerators

    NASA Astrophysics Data System (ADS)

    Hutton, A.

    1992-07-01

    Future accelerators will have to provide a high degree of reliability. Quality must be designed in right from the beginning and must remain a central theme throughout the project. The problem is similar to the problems facing US industry today, and examples of the successful application of quality engineering will be given. Different aspects of an accelerator project will be addressed: Concept, Design, Motivation, Management Techniques, and Fault Diagnosis. The importance of creating and maintaining a coherent team will be stressed.

  16. Microgravity Acceleration Measurement System

    NASA Technical Reports Server (NTRS)

    Foster, William

    2009-01-01

    Microgravity Acceleration Measurement System (MAMS) is an ongoing study of the small forces (vibrations and accelerations) on the ISS that result from the operation of hardware, crew activities, as well as dockings and maneuvering. Results will be used to generalize the types of vibrations affecting vibration-sensitive experiments. Investigators seek to better understand the vibration environment on the space station to enable future research.

  17. CEBAF Accelerator Achievements

    NASA Astrophysics Data System (ADS)

    Chao, Y. C.; Drury, M.; Hovater, C.; Hutton, A.; Krafft, G. A.; Poelker, M.; Reece, C.; Tiefenback, M.

    2011-05-01

    In the past decade, nuclear physics users of Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) have benefited from accelerator physics advances and machine improvements. As of early 2011, CEBAF operates routinely at 6 GeV, with a 12 GeV upgrade underway. This article reports highlights of CEBAF's scientific and technological evolution in the areas of cryomodule refurbishment, RF control, polarized source development, beam transport for parity experiments, magnets and hysteresis handling, beam breakup, and helium refrigerator operational optimization.

  18. Breakthrough: Fermilab Accelerator Technology

    ScienceCinema

    None

    2016-07-12

    There are more than 30,000 particle accelerators in operation around the world. At Fermilab, scientists are collaborating with other laboratories and industry to optimize the manufacturing processes for a new type of powerful accelerator that uses superconducting niobium cavities. Experimenting with unique polishing materials, a Fermilab team has now developed an efficient and environmentally friendly way of creating cavities that can propel particles with more than 30 million volts per meter.

  19. Rolamite acceleration sensor

    DOEpatents

    Abbin, Joseph P.; Briner, Clifton F.; Martin, Samuel B.

    1993-01-01

    A rolamite acceleration sensor which has a failsafe feature including a housing, a pair of rollers, a tension band wrapped in an S shaped fashion around the rollers, wherein the band has a force-generation cut out and a failsafe cut out or weak portion. The failsafe cut out or weak portion breaks when the sensor is subjected to an excessive acceleration so that the sensor fails in an open circuit (non-conducting) state permanently.

  20. Rolamite acceleration sensor

    DOEpatents

    Abbin, J.P.; Briner, C.F.; Martin, S.B.

    1993-12-21

    A rolamite acceleration sensor is described which has a failsafe feature including a housing, a pair of rollers, a tension band wrapped in an S shaped fashion around the rollers, wherein the band has a force-generation cut out and a failsafe cut out or weak portion. The failsafe cut out or weak portion breaks when the sensor is subjected to an excessive acceleration so that the sensor fails in an open circuit (non-conducting) state permanently. 6 figures.

  1. Collective field accelerator

    DOEpatents

    Luce, John S.

    1978-01-01

    A collective field accelerator which operates with a vacuum diode and utilizes a grooved cathode and a dielectric anode that operates with a relativistic electron beam with a .nu./.gamma. of .about. 1, and a plurality of dielectric lenses having an axial magnetic field thereabout to focus the collectively accelerated electrons and ions which are ejected from the anode. The anode and lenses operate as unoptimized r-f cavities which modulate and focus the beam.

  2. Accelerators for America's Future

    NASA Astrophysics Data System (ADS)

    Bai, Mei

    2016-03-01

    Particle accelerator, a powerful tool to energize beams of charged particles to a desired speed and energy, has been the working horse for investigating the fundamental structure of matter and fundermental laws of nature. Most known examples are the 2-mile long Stanford Linear Accelerator at SLAC, the high energy proton and anti-proton collider Tevatron at FermiLab, and Large Hadron Collider that is currently under operation at CERN. During the less than a century development of accelerator science and technology that led to a dazzling list of discoveries, particle accelerators have also found various applications beyond particle and nuclear physics research, and become an indispensible part of the economy. Today, one can find a particle accelerator at almost every corner of our lives, ranging from the x-ray machine at the airport security to radiation diagnostic and therapy in hospitals. This presentation will give a brief introduction of the applications of this powerful tool in fundermental research as well as in industry. Challenges in accelerator science and technology will also be briefly presented

  3. Biomedical accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Freeman, Stewart P. H. T.; Vogel, John S.

    1995-05-01

    Ultrasensitive SIMS with accelerator based spectrometers has recently begun to be applied to biomedical problems. Certain very long-lived radioisotopes of very low natural abundances can be used to trace metabolism at environmental dose levels ( [greater-or-equal, slanted] z mol in mg samples). 14C in particular can be employed to label a myriad of compounds. Competing technologies typically require super environmental doses that can perturb the system under investigation, followed by uncertain extrapolation to the low dose regime. 41Ca and 26Al are also used as elemental tracers. Given the sensitivity of the accelerator method, care must be taken to avoid contamination of the mass spectrometer and the apparatus employed in prior sample handling including chemical separation. This infant field comprises the efforts of a dozen accelerator laboratories. The Center for Accelerator Mass Spectrometry has been particularly active. In addition to collaborating with groups further afield, we are researching the kinematics and binding of genotoxins in-house, and we support innovative uses of our capability in the disciplines of chemistry, pharmacology, nutrition and physiology within the University of California. The field can be expected to grow further given the numerous potential applications and the efforts of several groups and companies to integrate more the accelerator technology into biomedical research programs; the development of miniaturized accelerator systems and ion sources capable of interfacing to conventional HPLC and GMC, etc. apparatus for complementary chemical analysis is anticipated for biomedical laboratories.

  4. TOPICS IN THE PHYSICS OF PARTICLE ACCELERATORS

    SciTech Connect

    Sessler, A.M.

    1984-07-01

    High energy physics, perhaps more than any other branch of science, is driven by technology. It is not the development of theory, or consideration of what measurements to make, which are the driving elements in our science. Rather it is the development of new technology which is the pacing item. Thus it is the development of new techniques, new computers, and new materials which allows one to develop new detectors and new particle-handling devices. It is the latter, the accelerators, which are at the heart of the science. Without particle accelerators there would be, essentially, no high energy physics. In fact. the advances in high energy physics can be directly tied to the advances in particle accelerators. Looking terribly briefly, and restricting one's self to recent history, the Bevatron made possible the discovery of the anti-proton and many of the resonances, on the AGS was found the {mu}-neutrino, the J-particle and time reversal non-invariance, on Spear was found the {psi}-particle, and, within the last year the Z{sub 0} and W{sup {+-}} were seen on the CERN SPS p-{bar p} collider. Of course one could, and should, go on in much more detail with this survey, but I think there is no need. It is clear that as better acceleration techniques were developed more and more powerful machines were built which, as a result, allowed high energy physics to advance. What are these techniques? They are very sophisticated and ever-developing. The science is very extensive and many individuals devote their whole lives to accelerator physics. As high energy experimental physicists your professional lives will be dominated by the performance of 'the machine'; i.e. the accelerator. Primarily you will be frustrated by the fact that it doesn't perform better. Why not? In these lectures, six in all, you should receive some appreciation of accelerator physics. We cannot, nor do we attempt, to make you into accelerator physicists, but we do hope to give you some insight into the

  5. Communication: UV photoionization of cytosine catalyzed by Ag{sup +}

    SciTech Connect

    Taccone, Martín I.; Berdakin, Matías; Pino, Gustavo A.; Féraud, Geraldine; Dedonder-Lardeux, Claude; Jouvet, Christophe

    2015-07-28

    The photo-induced damages of DNA in interaction with metal cations, which are found in various environments, still remain to be characterized. In this paper, we show how the complexation of a DNA base (cytosine (Cyt)) with a metal cation (Ag{sup +}) changes its electronic properties. By means of UV photofragment spectroscopy of cold ions, it was found that the photoexcitation of the CytAg{sup +} complex at low energy (315-282) nm efficiently leads to ionized cytosine (Cyt{sup +}) as the single product. This occurs through a charge transfer state in which an electron from the p orbital of Cyt is promoted to Ag{sup +}, as confirmed by ab initio calculations at the TD-DFT/B3LYP and RI-ADC(2) theory level using the SV(P) basis set. The low ionization energy of Cyt in the presence of Ag{sup +} could have important implications as point mutation of DNA upon sunlight exposition.

  6. 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.

  7. Theoretical study of CO oxidation on cationic, neutral, and anionic AuM dimers (M = Pd and Ag).

    PubMed

    Chen, Xuan; Lu, Rui-Feng; Kan, Er-Jun; Liu, Yu-Zhen; Xiao, Chuan-Yun; Deng, Kai-Ming

    2014-06-01

    The CO and O2 adsorption as well as CO oxidation on cationic, neutral, and anionic AuM dimers (M = Pd, Ag) are studied by density functional calculations. Our results show that CO and O2 are adsorbed more stably on AuPd dimers than on AuAg dimers with corresponding charge state. O2 is favorable to be adsorbed on Pd atom in AuPd(+), AuPd and AuPd(-) dimers. CO is adsorbed on Pd in AuPd and AuPd(-), while it is favorable to be adsorbed on Au in AuPd(+). For AuAg dimers, O2 is adsorbed on Ag in AuAg and AuAg(-), and it is adsorbed on Au in AuAg(+). CO is adsorbed on Ag in AuPd(-), while it is adsorbed on Au in AuAg and AuAg(+). The CO oxidation reaction is explored along two possible pathways: path-1 involves CO attacking the initial complexes of AuM dimers and O2, and path-2 is related to O2 interacting with the complexes of AuM dimers and CO. The charge state of AuM dimers has a substantial effect on CO oxidation. The reaction on AuPd(-) prefers path-1, and AuPd(+) mediated reaction proceeds along path-2, while CO oxidation on AuPd is difficult along both paths. For AuAg, both pathways are viable for AuAg(-) mediated reactions, while AuAg and AuAg(+) mediated reactions prefer path-2. Moreover, the energy barriers of CO oxidation on neutral AuAg is comparable with those on AuPd in all charge states while the energy barriers for AuAg(-) and AuAg(+) are considerably lower than those for all AuPd dimmers, indicating the impurity atom also plays a significant role in the catalytic activity. Furthermore, AuAg(-) is proposed to be the most active species due to the lowest barrier involved in the reaction.

  8. A new Schiff base based on vanillin and naphthalimide as a fluorescent probe for Ag+ in aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhou, Yanmei; Zhou, Hua; Ma, Tongsen; Zhang, Junli; Niu, Jingyang

    2012-03-01

    A new Schiff base based on vanillin and naphthalimide was designed and synthesized as fluorescent probe. The probe showed high selectivity for Ag+ over other metal ions such as Pb2+, Na+, K+, Cd2+, Ba2+, Cr3+, Zn2+, Cu2+, Ni2+, Ca2+, Al3+ and Mg2+ in aqueous solution. A new fluorescence emission was observed at 682 nm in the presence of Ag+ ion. The fluorescence intensity quenched with increasing the concentration of Ag+ at 682 nm. The method of job's plot confirmed the 1:2 complex between Ag+ and probe, and the mechanism was proposed.

  9. Transverse impedance measurement in RHIC and the AGS

    SciTech Connect

    Biancacci, Nicolo; Blaskiewicz, M.; Dutheil, Y.; Liu, C.; Mernick, M.; Minty, M.; White, S. M.

    2014-05-12

    The RHIC luminosity upgrade program aims for an increase of the polarized proton luminosity by a factor 2. To achieve this goal a significant increase in the beam intensity is foreseen. The beam coupling impedance could therefore represent a source of detrimental effects for beam quality and stability at high bunch intensities. For this reason it is essential to quantify the accelerator impedance budget and the major impedance sources, and possibly cure them. In this MD note we summarize the results of the 2013 transverse impedance measurements in the AGS and RHIC. The studies have been performed measuring the tune shift as a function of bunch intensity and deriving the total accelerator machine transverse impedance. For RHIC, we could obtain first promising results of impedance localization measurements as well.

  10. 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.

  11. A novel polythreading Ag(I) coordination polymer with blue photoluminescence

    SciTech Connect

    Duan, Xian-Ying; Yao, Jing; Lu, Chang-Sheng; Meng, Qing-Jin

    2013-04-15

    One new compound, [Ag(p-bix)]{sub 3}[Ag(Hbtc){sub 2}]·2H{sub 2}O (H{sub 3}btc=1,2,4-benzenetricarboxylate, p-bix=1,4-bis(imidazol-1-ylmethyl)-benzene), has been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, PXRD, luminescent analysis, and single-crystal X-ray diffraction. X-ray structural analysis revealed that 0-D unit [Ag(Hbtc){sub 2}]{sup 3−} and two kinds of 1-D linear chain [Ag(p-bix)]{sub ∞}{sup +}, can be found within the crystal structure. The combination of 0-D [Ag(Hbtc){sub 2}]{sup 3−} unit and 1-D undulated chain [Ag1(p{sub 1}-bix)]{sub ∞}{sup +} through weak Ag–O bond gave rise to 2-D anionic supramolecular doublelayer. Then the grids of the 2-D layer are threaded by 1-D linear cationic chain [Ag2(p{sub 2}-bix)]{sub ∞}{sup +} to generate entangled 3-D architecture with unusual poly(pseudo-rotaxane)-type arrangements. Luminescent properties of the title complex were also studied in this paper. - Graphical abstract: Novel 3D polythreading supramolecular architecture was constructed, in which 1D linear cationic chains [Ag(p{sub 2}-bix)]{sub ∞}{sup +} threaded into the grid of weak Ag–O bonded anionic 2D sheet. Highlights: ► Novel 1D{sup +}+2D{sup −}→3D polythreading coordination complex was reported. ► Diverse conformations of p-bix result in different 1D [Ag(p-bix)]{sub ∞}{sup +} chains. ► The title complex displayed blue photoluminescence at room temperature.

  12. Tetrasilvermesoperiodate, Ag 4H 2I 2O 10: Structure and Color Phenomenon

    NASA Astrophysics Data System (ADS)

    Trnoska, Andreas; Nachbaur, Edgar; Belaj, Ferdinand

    1994-12-01

    A single-crystal X-ray structural analysis of the material previously known as "Ag2HIO5" has shown it to be Ag4H2I2O10, Mr = 847.29, monoclinic, P21/n, a = 6.243(3), b = 7.247(3), c = 10.196(4) Å, β = 98.00(3)°, V = 456.8(3) Å3, Z = 2, Dx = 6.160 g cm-3, λ(MoKα) = 0.71069 Å, μ = 151.1 cm-1, F(000) = 744, T = 90K, R = 0.0570, wR = 0.0547, S = 1.85 for 898 unique observed reflections and 73 parameters. The dark-red crystal is composed of centrosymmetric H2I2O4-10 ions built up of two edge-sharing IO5(OH) units. The Ag+ ions equally surrounding the anion display the coordination numbers 5 and 7. The shortest Ag-Ag distance is 3.321(2) Å, revealing the absence of any attractive Ag-Ag interaction. The geometrical parameters obtained for the H2I2O4-10 ion are in close accordance with those reported for the same anion in the colorless alkaline metal salts. The color-induction phenomenon is due to considerable covalent Ag-O interaction causing a red shift of electronic transitions in the "cation-anion complex".

  13. Ag nanocrystal as a promoter for carbon nanotube-based room-temperature gas sensors.

    PubMed

    Cui, Shumao; Pu, Haihui; Mattson, Eric C; Lu, Ganhua; Mao, Shun; Weinert, Michael; Hirschmugl, Carol J; Gajdardziska-Josifovska, Marija; Chen, Junhong

    2012-09-28

    We have investigated the room-temperature sensing enhancement of Ag nanoparticles (NPs) for multiwalled carbon nanotube (MWCNT)-based gas sensors using electrical measurements, in situ infrared (IR) microspectroscopy, and density functional theory (DFT) calculations. Multiple hybrid nanosensors with structures of MWCNTs/SnO(2)/Ag and MWCNTs/Ag have been synthesized using a process that combines a simple mini-arc plasma with electrostatic force directed assembly, and characterized by electron microscopy techniques. Ag NPs were found to enhance the sensing behavior through the "electronic sensitization" mechanism. In contrast to sensors based on bare MWCNTs and MWCNTs/SnO(2), sensors with Ag NPs show not only higher sensitivity and faster response to NO(2) but also significantly enhanced sensitivity to NH(3). Our DFT calculations indicate that the increased sensitivity to NO(2) is attributed to the formation of a NO(3) complex with oxygen on the Ag surface accompanying a charge rearrangement and a net electron transfer from the hybrid to NO(2). The significant response to NH(3) is predicted to arise because NH(3) is attracted to hollow sites on the oxidized Ag surface with the H atoms pointing towards Ag atoms and electron donation from H to the hybrid sensor.

  14. A Redox Shuttle Accelerates O2 Evolution of Photocatalysts Formed In Situ under Visible Light.

    PubMed

    Li, Jia-Xin; Ye, Chen; Li, Xu-Bing; Li, Zhi-Jun; Gao, Xue-Wang; Chen, Bin; Tung, Chen-Ho; Wu, Li-Zhu

    2017-02-20

    A redox shuttle strategy is demonstrated to be a promising approach to accelerate hole removal for efficient O2 production with mesoporous graphitic carbon nitride, WO3 , BiVO4 , NiTi-LDH, and Ag3 PO4 water-oxidation catalysts under visible-light irradiation.

  15. Quasi-Instantaneous Bacterial Inactivation on Cu-Ag Nanoparticulate 3D Catheters in the Dark and Under Light: Mechanism and Dynamics.

    PubMed

    Rtimi, Sami; Sanjines, Rosendo; Pulgarin, Cesar; Kiwi, John

    2016-01-13

    The first evidence for Cu-Ag (50%/50%) nanoparticulate hybrid coatings is presented leading to a complete and almost instantaneous bacterial inactivation in the dark (≤5 min). Dark bacterial inactivation times on Cu-Ag (50%/50%) were observed to coincide with the times required by actinic light irradiation. This provides the evidence that the bimetal Cu-Ag driven inactivation predominates over a CuO/Cu2O and Ag2O oxides inducing a semiconductor driven behavior. Cu- or Ag-coated polyurethane (PU) catheters led to bacterial inactivation needing about ∼30 min. The accelerated bacterial inactivation by Cu-Ag coated on 3D catheters sputtered was investigated in a detailed way. The release of Cu/Ag ions during bacterial inactivation was followed by inductively coupled plasma mass-spectrometry (ICP-MS) and the amount of Cu and Ag-ions released were below the cytotoxicity levels permitted by the sanitary regulations. By stereomicroscopy the amount of live/dead cells were followed during the bacterial inactivation time. By Fourier transform infrared spectroscopy (FTIR), the systematic shift of the -(CH2) band stretching of the outer lipo-polysaccharide bilayer (LPS) was followed to monitor the changes leading to cell lysis. A hydrophobic to hydrophilic transformation of the Cu-Ag PU catheter surface under light was observed within 30 min followed concomitantly to a longer back transformation to the hydrophobic initial state in the dark. Physical insight is provided for the superior performance of Cu-Ag films compared to Cu or Ag films in view of the drastic acceleration of the bacterial inactivation observed on bimetal Cu-Ag films coating PU catheters. A mechanism of bacterial inactivation is suggested that is consistent with the findings reported in this study.

  16. Synthesis and antimicrobial activities of silver(I) sulfanylcarboxylates. Structural isomers with identically or unequally coordinated Ag centers in an Ag4S4 ring.

    PubMed

    Barreiro, Elena; Casas, José S; Couce, María D; Sánchez, Agustín; Seoane, Rafael; Sordo, José; Varela, José M; Vázquez-López, Ezequiel M

    2007-07-28

    We have investigated the reactions of silver nitrate and 3-(aryl)-2-sulfanylpropenoic acids [H(2)xspa, x: p = 3-phenyl-, f = 3-(2-furyl)-, t = 3-(2-thienyl)-, py = 3-(2-pyridyl)-] and 2-cyclopentylidene-2-sulfanylacetic acid (H(2)L) in 1 : 1 and 2 : 1 molar ratios. The 1 : 1 molar ratio gave compounds of type [Ag(HL)]; reaction of these compounds with diisopropylamine and NaOH gave [HQ][Ag(L)] (HQ = diisopropylammonium) and Na[Ag(L)] x H(2)O, respectively. These compounds, as well as those of type [Ag(2)(L)] obtained with the 1 : 2 molar ratio, were isolated and characterized by IR and NMR ((1)H and (13)C) spectroscopy. (109)Ag NMR spectroscopy and ESI-MS spectrometry were also used in some cases. The crystal structures of [HQ][Ag(pspa)] (11), in which the presence of structural isomers was detected, and [HQ][Ag(cpa)] (15) were determined by X-ray diffractometry. The antimicrobial activity of the complexes against E. coli, S. aureus, B. subtilis, P. aeruginosa/Resistant P. aeruginosa, and C. albicans was tested.

  17. Fermilab accelerator control system: Analog monitoring facilities

    SciTech Connect

    Seino, K.; Anderson, L.; Smedinghoff, J.

    1987-10-01

    Thousands of analog signals are monitored in different areas of the Fermilab accelerator complex. For general purposes, analog signals are sent over coaxial or twinaxial cables with varying lengths, collected at fan-in boxes and digitized with 12 bit multiplexed ADCs. For higher resolution requirements, analog signals are digitized at sources and are serially sent to the control system. This paper surveys ADC subsystems that are used with the accelerator control systems and discusses practical problems and solutions, and it describes how analog data are presented on the console system.

  18. Centrifuge Study of Pilot Tolerance to Acceleration and the Effects of Acceleration on Pilot Performance

    NASA Technical Reports Server (NTRS)

    Creer, Brent Y.; Smedal, Harald A.; Wingrove, Rodney C.

    1960-01-01

    A research program the general objective of which was to measure the effects of various sustained accelerations on the control performance of pilots, was carried out on the Aviation Medical Acceleration Laboratory centrifuge, U.S. Naval Air Development Center, Johnsville, PA. The experimental setup consisted of a flight simulator with the centrifuge in the control loop. The pilot performed his control tasks while being subjected to acceleration fields such as might be encountered by a forward-facing pilot flying an atmosphere entry vehicle. The study was divided into three phases. In one phase of the program, the pilots were subjected to a variety of sustained linear acceleration forces while controlling vehicles with several different sets of longitudinal dynamics. Here, a randomly moving target was displayed to the pilot on a cathode-ray tube. For each combination of acceleration field and vehicle dynamics, pilot tracking accuracy was measured and pilot opinion of the stability and control characteristics was recorded. Thus, information was obtained on the combined effects of complexity of control task and magnitude and direction of acceleration forces on pilot performance. These tests showed that the pilot's tracking performance deteriorated markedly at accelerations greater than about 4g when controlling a lightly damped vehicle. The tentative conclusion was also reached that regardless of the airframe dynamics involved, the pilot feels that in order to have the same level of control over the vehicle, an increase in the vehicle dynamic stability was required with increases in the magnitudes of the acceleration impressed upon the pilot. In another phase, boundaries of human tolerance of acceleration were established for acceleration fields such as might be encountered by a pilot flying an orbital vehicle. A special pilot restraint system was developed to increase human tolerance to longitudinal decelerations. The results of the tests showed that human tolerance

  19. Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles. Part 1. Aggregation and dissolution.

    PubMed

    Unrine, Jason M; Colman, Benjamin P; Bone, Audrey J; Gondikas, Andreas P; Matson, Cole W

    2012-07-03

    To better understand their fate and toxicity in aquatic environments, we compared the aggregation and dissolution behavior of gum arabic (GA) and polyvinylpyrrolidone (PVP) coated Ag nanoparticles (NPs) in aquatic microcosms. There were four microcosm types: surface water; water and sediment; water and aquatic plants; or water, sediment, and aquatic plants. Dissolution and aggregation behavior of AgNPs were examined using ultracentrifugation, ultrafiltration, and asymmetrical flow field flow fractionation coupled to ultraviolet-visible spectroscopy, dynamic and static laser light scattering, and inductively coupled plasma mass spectrometry. Plants released dissolved organic matter (DOM) into the water column either through active or passive processes in response to Ag exposure. This organic matter fraction readily bound Ag ions. The plant-derived DOM had the effect of stabilizing PVP-AgNPs as primary particles, but caused GA-AgNPs to be removed from the water column, likely by dissolution and binding of released Ag ions on sediment and plant surfaces. The destabilization of the GA-AgNPs also corresponded with X-ray absorption near edge spectroscopy results which suggest that 22-28% of the particulate Ag was associated with thiols and 5-14% was present as oxides. The results highlight the potential complexities of nanomaterial behavior in response to biotic and abiotic modifications in ecosystems, and may help to explain differences in toxicity of Ag observed in realistic exposure media compared to simplified laboratory exposures.

  20. Laser Ion Acceleration Control

    NASA Astrophysics Data System (ADS)

    Kawata, Shigeo; Nagashima, T.; Izumiyama, T.; Sato, D.; Takano, M.; Barada, D.; Ma, Y. Y.; Gu, Y. J.; Kong, Q.; Wang, P. X.; Wang, W. M.

    2013-10-01

    An intense femtosecond pulsed laser is employed to accelerate ions. The issues in the laser ion accelerator include the energy efficiency from the laser to the ions, the ion beam collimation, the ion energy spectrum control, the ion beam bunching, the ion particle energy control, etc. In the study particle computer simulations were performed to solve the issues, and each component was designed to control the ion beam quality. When an intense laser illuminates a target, electrons in the target are accelerated and leave from the target; temporarily a strong electric field is formed between the high-energy electrons and the target ions, and the target ions are accelerated. The energy efficiency from the laser to ions was improved by using a solid target with a fine sub-wavelength structure or by a near critical density gas plasma. The ion beam collimation was realized by holes behind the solid target. The control of the ion energy spectrum and the ion particle energy, and the ion beam bunching were successfully realized by a multi-stage laser-target interaction. The present study proposed a novel concept for a future compact laser ion accelerator, based on each component study required to control the ion beam quality and parameters. Partly supported by JSPS, MEXT, CORE, Japan/US Cooperation program, ASHULA and ILE/Osaka University.

  1. Dielectric laser accelerators

    NASA Astrophysics Data System (ADS)

    England, R. Joel; Noble, Robert J.; Bane, Karl; Dowell, David H.; Ng, Cho-Kuen; Spencer, James E.; Tantawi, Sami; Wu, Ziran; Byer, Robert L.; Peralta, Edgar; Soong, Ken; Chang, Chia-Ming; Montazeri, Behnam; Wolf, Stephen J.; Cowan, Benjamin; Dawson, Jay; Gai, Wei; Hommelhoff, Peter; Huang, Yen-Chieh; Jing, Chunguang; McGuinness, Christopher; Palmer, Robert B.; Naranjo, Brian; Rosenzweig, James; Travish, Gil; Mizrahi, Amit; Schachter, Levi; Sears, Christopher; Werner, Gregory R.; Yoder, Rodney B.

    2014-10-01

    The use of infrared lasers to power optical-scale lithographically fabricated particle accelerators is a developing area of research that has garnered increasing interest in recent years. The physics and technology of this approach is reviewed, which is referred to as dielectric laser acceleration (DLA). In the DLA scheme operating at typical laser pulse lengths of 0.1 to 1 ps, the laser damage fluences for robust dielectric materials correspond to peak surface electric fields in the GV /m regime. The corresponding accelerating field enhancement represents a potential reduction in active length of the accelerator between 1 and 2 orders of magnitude. Power sources for DLA-based accelerators (lasers) are less costly than microwave sources (klystrons) for equivalent average power levels due to wider availability and private sector investment. Because of the high laser-to-particle coupling efficiency, required pulse energies are consistent with tabletop microJoule class lasers. Combined with the very high (MHz) repetition rates these lasers can provide, the DLA approach appears promising for a variety of applications, including future high-energy physics colliders, compact light sources, and portable medical scanners and radiative therapy machines.

  2. Electrostatic Plasma Accelerator (EPA)

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1989-01-01

    The Electrostatic Plasma Accelerator (EPA) is a thruster concept which promises specific impulse levels between low power arcjets and those of the ion engine while retaining the relative simplicity of the arcjet. The EPA thruster produces thrust through the electrostatic acceleration of a moderately dense plasma. No accelerating electrodes are used and the specific impulse is a direct function of the applied discharge voltage and the propellant atomic mass. The goal of the present program is to demonstrate feasibility of the EPA thruster concept through experimental and theoretical investigations of the EPA acceleration mechanism and discharge chamber performance. Experimental investigations will include operating the test bed ion (TBI) engine as an EPA thruster and parametrically varying the thruster geometry and operating conditions to quantify the electrostatic plasma acceleration effect. The theoretical investigations will include the development of a discharge chamber model which describes the relationships between the engine size, plasma properties, and overall performance. For the EPA thruster to be a viable propulsion concept, overall thruster efficiencies approaching 30% with specific impulses approaching 1000 s must be achieved.

  3. Advanced accelerator theory development

    SciTech Connect

    Sampayan, S.E.; Houck, T.L.; Poole, B.; Tishchenko, N.; Vitello, P.A.; Wang, I.

    1998-02-09

    A new accelerator technology, the dielectric wall accelerator (DWA), is potentially an ultra compact accelerator/pulsed power driver. This new accelerator relies on three new components: the ultra-high gradient insulator, the asymmetric Blumlein and low jitter switches. In this report, we focused our attention on the first two components of the DWA system the insulators and the asymmetric Blumlein. First, we sought to develop the necessary design tools to model and scale the behavior of the high gradient insulator. To perform this task we concentrated on modeling the discharge processes (i.e., initiation and creation of the surface discharge). In addition, because these high gradient structures exhibit favorable microwave properties in certain accelerator configurations, we performed experiments and calculations to determine the relevant electromagnetic properties. Second, we performed circuit modeling to understand energy coupling to dynamic loads by the asymmetric Blumlein. Further, we have experimentally observed a non-linear coupling effect in certain asymmetric Blumlein configurations. That is, as these structures are stacked into a complete module, the output voltage does not sum linearly and a lower than expected output voltage results. Although we solved this effect experimentally, we performed calculations to understand this effect more fully to allow better optimization of this DWA pulse-forming line system.

  4. 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.

  5. 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.

  6. Plasma-based accelerator structures

    SciTech Connect

    Schroeder, Carl B.

    1999-12-01

    Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating structure, the generation of ultrashort electron bunches, and the propagation of laser pulses is underdense plasmas.

  7. Industrialization of Superconducting RF Accelerator Technology

    NASA Astrophysics Data System (ADS)

    Peiniger, Michael; Pekeler, Michael; Vogel, Hanspeter

    2012-01-01

    Superconducting RF (SRF) accelerator technology has basically existed for 50 years. It took about 20 years to conduct basic R&D and prototyping at universities and international institutes before the first superconducting accelerators were built, with industry supplying complete accelerator cavities. In parallel, the design of large scale accelerators using SRF was done worldwide. In order to build those accelerators, industry has been involved for 30 years in building the required cavities and/or accelerator modules in time and budget. To enable industry to supply these high tech components, technology transfer was made from the laboratories in the following three regions: the Americas, Asia and Europe. As will be shown, the manufacture of the SRF cavities is normally accomplished in industry whereas the cavity testing and module assembly are not performed in industry in most cases, yet. The story of industrialization is so far a story of customized projects. Therefore a real SRF accelerator product is not yet available in this market. License agreements and technology transfer between leading SRF laboratories and industry is a powerful tool for enabling industry to manufacture SRF components or turnkey superconducting accelerator modules for other laboratories and users with few or no capabilities in SRF technology. Despite all this, the SRF accelerator market today is still a small market. The manufacture and preparation of the components require a range of specialized knowledge, as well as complex and expensive manufacturing installations like for high precision machining, electron beam welding, chemical surface preparation and class ISO4 clean room assembly. Today, the involved industry in the US and Europe comprises medium-sized companies. In Japan, some big enterprises are involved. So far, roughly 2500 SRF cavities have been built by or ordered from industry worldwide. Another substantial step might come from the International Linear Collider (ILC) project

  8. Metal Cyanide Ions Mx(CN)y]+,- in the gas phase: M = Fe, Co, Ni, Zn, Cd, Hg, Fe + Ag, Co + Ag.

    PubMed

    Dance, Ian G; Dean, Philip A W; Fisher, Keith J; Harris, Hugh H

    2002-07-01

    The generation of metal cyanide ions in the gas phase by laser ablation of M(CN)(2) (M = Co, Ni, Zn, Cd, Hg), Fe(III)[Fe(III)(CN)(6)] x xH(2)O, Ag(3)[M(CN)(6)] (M = Fe, Co), and Ag(2)[Fe(CN)(5)(NO)] has been investigated using Fourier transform ion cyclotron resonance mass spectrometry. Irradiation of Zn(CN)(2) and Cd(CN)(2) produced extensive series of anions, [Zn(n)(CN)(2n+1)](-) (1 < or = n < or = 27) and [Cd(n)(CN)(2n+1)](-) (n = 1, 2, 8-27, and possibly 29, 30). Cations Hg(CN)(+) and [Hg(2)(CN)(x)](+) (x = 1-3), and anions [Hg(CN)(x)](-) (x = 2, 3), are produced from Hg(CN)(2). Irradiation of Fe(III)[Fe(III)(CN)(6)] x xH(2)O gives the anions [Fe(CN)(2)](-), [Fe(CN)(3)](-), [Fe(2)(CN)(3)](-), [Fe(2)(CN)(4)](-), and [Fe(2)(CN)(5)](-). When Ag(3)[Fe(CN)(6)] is ablated, [AgFe(CN)(4)](-) and [Ag(2)Fe(CN)(5)](-) are observed together with homoleptic anions of Fe and Ag. The additional heterometallic complexes [AgFe(2)(CN)(6)](-), [AgFe(3)(CN)(8)](-), [Ag(2)Fe(2)(CN)(7)](-), and [Ag(3)Fe(CN)(6)](-) are observed on ablation of Ag(2)[Fe(CN)(5)(NO)]. Homoleptic anions [Co(n)(CN)(n+1)](-) (n = 1-3), [Co(n)(CN)(n+2)](-) (n = 1-3), [Co(2)(CN)(4)](-), and [Co(3)(CN)(5)](-) are formed when anhydrous Co(CN)(2) is the target. Ablation of Ag(3)[Co(CN)(6)] yields cations [Ag(n)(CN)(n-1)](+) (n = 1-4) and [Ag(n)Co(CN)(n)](+) (n = 1, 2) and anions [Ag(n)(CN)(n+1)](-) (n = 1-3), [Co(n)(CN)(n-1)](-) (n = 1, 2), [Ag(n)Co(CN)(n+2)](-) (n = 1, 2), and [Ag(n)Co(CN)(n+3)](-) (n = 0-2). The Ni(I) species [Ni(n)(CN)(n-1)](+) (n = 1-4) and [Ni(n)(CN)(n+1)](-) (n = 1-3) are produced when anhydrous Ni(CN)(2) is irradiated. In all cases, CN(-) and polyatomic carbon nitride ions C(x)N(y)(-) are formed concurrently. On the basis of density functional calculations, probable structures are proposed for most of the newly observed species. General structural features are low coordination numbers, regular trigonal coordination stereochemistry for d(10) metals but distorted trigonal stereochemistry

  9. Novel Asymmetric Wettable AgNPs/Chitosan Wound Dressing: In Vitro and In Vivo Evaluation.

    PubMed

    Liang, Donghui; Lu, Zhong; Yang, Hao; Gao, Jingting; Chen, Rong

    2016-02-17

    A novel silver nanoparticles (AgNPs)/chitosan composite dressing with asymmetric wettability surfaces was successfully prepared via a simple two-step method for biomedical applications as wound healing materials. First, AgNPs were assembled into the chitosan sponge which was prepared by lyophilization process. Then one side of the sponge was modified by a thin layer of stearic acid. The incorporation of AgNPs into chitosan dressing could enhance the antibacterial activity against drug-sensitive and drug-resistant pathogenic bacteria. The asymmetric surface modification endows the dressing with both highly hydrophobic property and inherent hydrophilic nature of chitosan. The hydrophobic surface of the dressing shows waterproof and antiadhesion for contaminant properties, whereas the hydrophilic surface preserves its water-absorbing capability and efficiently inhibits the growth of bacteria. Furthermore, the AgNPs/chitosan composite dressing displays improved moisture retention and blood clotting ability compared to the unmodified dressings. Cytocompatibility test evaluated in vitro and in a wound infection model illustrates the nontoxic nature of the composite dressing. More importantly, the in vivo wound healing model evaluation in mice reveals that the asymmetric AgNPs/chitosan dressing promotes the wound healing and accelerates the reepithelialization and collagen deposition. The silver accumulation in mice body treated by the composite dressing is far lower than that of the clinically used Acasin nanosilver dressing treated mice. This work indicates the huge potential of the novel AgNPs/chitosan wound dressing with asymmetrical wettability for clinical use.

  10. Perturbations for transient acceleration

    SciTech Connect

    Vargas, Cristofher Zuñiga; Zimdahl, Winfried; Hipólito-Ricaldi, Wiliam S. E-mail: hipolito@ceunes.ufes.br

    2012-04-01

    According to the standard ΛCDM model, the accelerated expansion of the Universe will go on forever. Motivated by recent observational results, we explore the possibility of a finite phase of acceleration which asymptotically approaches another period of decelerated expansion. Extending an earlier study on a corresponding homogeneous and isotropic dynamics, in which interactions between dark matter and dark energy are crucial, the present paper also investigates the dynamics of the matter perturbations both on the Newtonian and General Relativistic (GR) levels and quantifies the potential relevance of perturbations of the dark-energy component. In the background, the model is tested against the Supernova type Ia (SNIa) data of the Constitution set and on the perturbative level against growth rate data, among them those of the WiggleZ survey, and the data of the 2dFGRS project. Our results indicate that a transient phase of accelerated expansion is not excluded by current observations.

  11. Uniform acceleration in general relativity

    NASA Astrophysics Data System (ADS)

    Friedman, Yaakov; Scarr, Tzvi

    2015-10-01

    We extend de la Fuente and Romero's (Gen Relativ Gravit 47:33, 2015) defining equation for uniform acceleration in a general curved spacetime from linear acceleration to the full Lorentz covariant uniform acceleration. In a flat spacetime background, we have explicit solutions. We use generalized Fermi-Walker transport to parallel transport the Frenet basis along the trajectory. In flat spacetime, we obtain velocity and acceleration transformations from a uniformly accelerated system to an inertial system. We obtain the time dilation between accelerated clocks. We apply our acceleration transformations to the motion of a charged particle in a constant electromagnetic field and recover the Lorentz-Abraham-Dirac equation.

  12. Synthesis and evaluation of α-Ag2WO4 as novel antifungal agent

    NASA Astrophysics Data System (ADS)

    Foggi, Camila C.; Fabbro, Maria T.; Santos, Luís P. S.; de Santana, Yuri V. B.; Vergani, Carlos E.; Machado, Ana L.; Cordoncillo, Eloisa; Andrés, Juan; Longo, Elson

    2017-04-01

    Because of the need for new antifungal materials with greater potency, microcrystals of α-Ag2WO4, a complex metal oxide, have been synthetized by a simple co-precipitation method, and their antifungal activity against Candida albicans has been investigated. A theoretical model based on clusters that are building blocks of α-Ag2WO4 has been proposed to explain the experimental results.

  13. Preparation and characterization of Ag-cluster in poly(methylmethacrylate)

    SciTech Connect

    Yanagihara, Naohisa; Ishii, Yoshitaka; Kawase, Takanori; Kaneko, Toshimare; Horie, Hisashi; Hara, Toru

    1997-09-01

    Solid sols of silver in poly(methylmethacrylate), Ag/PMMA, were prepared by bulk polymerization of methyl methacrylate (MMA) with benzoyl peroxide (BPO) as an initiator in the presence of silver(I) trifluoroacetate. Ag/PMMAs were characterized by visible spectroscopy. Effects of the concentration of initiator, the concentration of silver(I) complex and the heat-treatment time on the formation of silver cluster were studied in detail.

  14. A comparison of metallophilic interactions in group 11[X-M-PH 3] n ( n = 2-3) complex halides (M = Cu, Ag, Au; X = Cl, Br, I) from density functional theory

    NASA Astrophysics Data System (ADS)

    Assadollahzadeh, Behnam; Schwerdtfeger, Peter

    2008-09-01

    Metallophilic interactions in dimeric and trimeric [X-M-PH 3] n ( n = 2-3) complexes are studied using density functional and second order Møller Plesset perturbation theory together with energy-consistent, small-core scalar-relativistic pseudopotentials and corresponding large sized valence basis sets. A many-body decomposition of the interaction energy shows that the three-body contribution to the metallophilic interaction is repulsive at all levels of theory and non-negligible. However, the two-body contribution of the two end units dominates over the three-body effect, giving a net stabilizing effect in the metal-metal interaction from the dimer to the trimer, and resulting in a further contraction of the trimer metal-metal bond.

  15. Microelectromechanical acceleration-sensing apparatus

    DOEpatents

    Lee, Robb M.; Shul, Randy J.; Polosky, Marc A.; Hoke, Darren A.; Vernon, George E.

    2006-12-12

    An acceleration-sensing apparatus is disclosed which includes a moveable shuttle (i.e. a suspended mass) and a latch for capturing and holding the shuttle when an acceleration event is sensed above a predetermined threshold level. The acceleration-sensing apparatus provides a switch closure upon sensing the acceleration event and remains latched in place thereafter. Examples of the acceleration-sensing apparatus are provided which are responsive to an acceleration component in a single direction (i.e. a single-sided device) or to two oppositely-directed acceleration components (i.e. a dual-sided device). A two-stage acceleration-sensing apparatus is also disclosed which can sense two acceleration events separated in time. The acceleration-sensing apparatus of the present invention has applications, for example, in an automotive airbag deployment system.

  16. Diffusive Shock Acceleration

    NASA Astrophysics Data System (ADS)

    Baring, Matthew

    2003-04-01

    The process of diffusive acceleration of charged particles in shocked plasmas is widely invoked in astrophysics to account for the ubiquitous presence of signatures of non-thermal relativistic electrons and ions in the universe. This statistical energization mechanism, manifested in turbulent media, was first posited by Enrico Fermi in 1949 to explain the observed cosmic ray population, which exhibits an almost power-law distribution in rigidity. The absence of a momentum scale is a key characteristic of diffusive shock acceleration, and astrophysical systems generally only impose scales at the injection (low energy) and loss (high energy) ends of the particle spectrum. The existence of structure in the cosmic ray spectrum (the "knee") at around 3000 TeV has promoted contentions that there are at least two origins for cosmic rays, a galactic one supplying those up to the knee, and perhaps an extragalactic one that can explain even the ultra-high energy cosmic rays (UHECRs) seen at 1-300 EeV. Accounting for the UHECRs with familiar astrophysical sites of acceleration has historically proven difficult due to the need to assume high magnetic fields in order to reduce the shortest diffusive acceleration timescale, the ion gyroperiod, to meaningful values. Yet active galaxies and gamma-ray bursts remain strong and interesting candidate sources for UHECRs, turning the theoretical focus to relativistic shocks. This review summarizes properties of diffusive shock acceleration that are salient to the issue of UHECR generation. These include spectral indices, anisotropies, acceleration efficencies and timescales, as functions of the shock speed and mean field orientation, and also the degree of field turbulence. Astrophysical sites for UHECR production are also critiqued.

  17. Crystal structure of [Ag(NH3)3]2[Ag(NH3)2]2[SnF6]F2, a compound showing argentophilic inter­actions

    PubMed Central

    Kraus, Florian; Fichtl, Matthias; Baer, Sebastian

    2016-01-01

    Bis[triamminesilver(I)] bis­[diamminesilver(I)] hexa­fluorido­stannate(IV) difluoride, [Ag(NH3)3]2[Ag(NH3)2]2[SnF6]F2, was obtained in the form of colourless crystals from the reaction of CsAgSnF7 in anhydrous ammonia. Two different ammine complexes of silver(I) are present in the structure, i.e. a linear diammine and a T-shaped triammine complex. The ammine silver(I) complexes show Ag⋯Ag distances in the range of argentophilic inter­actions. In the crystal, several N—H⋯F hydrogen bonds are present between the complex cations and the SbF6 − and F− anions, leading to the formation of a three-dimensional network. PMID:27980850

  18. 'Light Sail' Acceleration Reexamined

    SciTech Connect

    Macchi, Andrea; Veghini, Silvia; Pegoraro, Francesco

    2009-08-21

    The dynamics of the acceleration of ultrathin foil targets by the radiation pressure of superintense, circularly polarized laser pulses is investigated by analytical modeling and particle-in-cell simulations. By addressing self-induced transparency and charge separation effects, it is shown that for 'optimal' values of the foil thickness only a thin layer at the rear side is accelerated by radiation pressure. The simple 'light sail' model gives a good estimate of the energy per nucleon, but overestimates the conversion efficiency of laser energy into monoenergetic ions.

  19. HIGH GRADIENT INDUCTION ACCELERATOR

    SciTech Connect

    Caporaso, G J; Sampayan, S; Chen, Y; Blackfield, D; Harris, J; Hawkins, S; Holmes, C; Krogh, M; Nelson, S; Nunnally, W; Paul, A; Poole, B; Rhodes, M; Sanders, D; Selenes, K; Sullivan, J; Wang, L; Watson, J

    2007-06-21

    A new type of compact induction accelerator is under development at the Lawrence Livermore National Laboratory that promises to increase the average accelerating gradient by at least an order of magnitude over that of existing induction machines. The machine is based on the use of high gradient vacuum insulators, advanced dielectric materials and switches and is stimulated by the desire for compact flash x-ray radiography sources. Research describing an extreme variant of this technology aimed at proton therapy for cancer will be described. Progress in applying this technology to several applications will be reviewed.

  20. "Light sail" acceleration reexamined.

    PubMed

    Macchi, Andrea; Veghini, Silvia; Pegoraro, Francesco

    2009-08-21

    The dynamics of the acceleration of ultrathin foil targets by the radiation pressure of superintense, circularly polarized laser pulses is investigated by analytical modeling and particle-in-cell simulations. By addressing self-induced transparency and charge separation effects, it is shown that for "optimal" values of the foil thickness only a thin layer at the rear side is accelerated by radiation pressure. The simple "light sail" model gives a good estimate of the energy per nucleon, but overestimates the conversion efficiency of laser energy into monoenergetic ions.

  1. High intensity hadron accelerators

    SciTech Connect

    Teng, L.C.

    1989-05-01

    This rapporteur report consists mainly of two parts. Part I is an abridged review of the status of all High Intensity Hadron Accelerator projects in the world in semi-tabulated form for quick reference and comparison. Part II is a brief discussion of the salient features of the different technologies involved. The discussion is based mainly on my personal experiences and opinions, tempered, I hope, by the discussions I participated in in the various parallel sessions of the workshop. In addition, appended at the end is my evaluation and expression of the merits of high intensity hadron accelerators as research facilities for nuclear and particle physics.

  2. Improved scaling of temperature-accelerated dynamics using localization.

    PubMed

    Shim, Yunsic; Amar, Jacques G

    2016-07-07

    While temperature-accelerated dynamics (TAD) is a powerful method for carrying out non-equilibrium simulations of systems over extended time scales, the computational cost of serial TAD increases approximately as N(3) where N is the number of atoms. In addition, although a parallel TAD method based on domain decomposition [Y. Shim et al., Phys. Rev. B 76, 205439 (2007)] has been shown to provide significantly improved scaling, the dynamics in such an approach is only approximate while the size of activated events is limited by the spatial decomposition size. Accordingly, it is of interest to develop methods to improve the scaling of serial TAD. As a first step in understanding the factors which determine the scaling behavior, we first present results for the overall scaling of serial TAD and its components, which were obtained from simulations of Ag/Ag(100) growth and Ag/Ag(100) annealing, and compare with theoretical predictions. We then discuss two methods based on localization which may be used to address two of the primary "bottlenecks" to the scaling of serial TAD with system size. By implementing both of these methods, we find that for intermediate system-sizes, the scaling is improved by almost a factor of N(1/2). Some additional possible methods to improve the scaling of TAD are also discussed.

  3. 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.

  4. Evolution of full-length genomes of HBV quasispecies in sera of patients with a coexistence of HBsAg and anti-HBs antibodies.

    PubMed

    Zhou, Tai-Cheng; Li, Xiao; Li, Long; Li, Xiao-Fei; Zhang, Liang; Wei, Jia

    2017-04-06

    Although the evolutionary changes of viral quasispecies are correlated to the pathological status of a disease, little is known in the coexistence of hepatitis B surface antigen (HBsAg) and antibodies to these antigens (anti-HBs). To examine evolutionary changes in hepatitis B virus (HBV) and their relationship to the coexistence of HBsAg and anti-HBs antibodies, HBV genomes in patients with a coexistence of HBsAg and anti-HBs antibodies (experimental group) and HBsAg positive without anti-HBs (control group) were assessed. Our results showed that quasispecies diversity was significantly higher in the experimental group for large HBsAg (LHBsAg), middle HBsAg (MHBsAg), and HBsAg genes. LHBsAg harbored dN/dS values eight times higher in the experimental group; however, the mean dN/dS ratios in genes HbxAg, Pol and PreC/C of the experimental patients had an opposite trend. Phylogenetic trees in the experimental group were more complex than the control group. More positive selection sites, mutations and deletions were observed in the experimental group in specific regions. Furthermore, several amino acid variants in epitopes were potentially associated with the immune evasion. In conclusion, cumulative evolutionary changes in HBV genome that facilitate immune evasion provide insights into the genetic mechanism of a coexistence of HBsAg and anti-HBs antibodies.

  5. 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.

  6. Multileaf collimator for Coline medical accelerators

    NASA Astrophysics Data System (ADS)

    Harasimowicz, Janusz; Plebański, Grzegorz; Sajna, Krzysztof

    2008-01-01

    Multileaf collimator (MLC) allows advanced field shaping for radiation therapy delivered with medical accelerators. In this paper theoretical considerations and scientific studies of a new MLC design are described. Considered multileaf collimator model comprises of a multiplicity of tungsten leaves of 1 cm width projected at isocenter plane. To ensure compatibility of a new MLC solution with different accelerator types as well as to assure high reliability in irradiated environment and presence of strong magnetic field, a complex and independent control system had to be developed. It comprises of two modules - one placed in the accelerator treatment head and the other one placed in the control room. Both of them ensure high reliability and treatment quality while working in harsh conditions. Mechanical design and leaf shape optimization algorithm based on a ray tracing method are also described in details. Adapted solutions allowed providing minimized and uniform radiation penumbrae in the full range of leaves positions which is crucial for modern advanced radiotherapy.

  7. Manifold damping of the NLC detuned accelerating structure

    NASA Astrophysics Data System (ADS)

    Kroll, N.; Thompson, K.; Bane, K.; Gluckstern, R.; Ko, K.; Miller, R.; Ruth, R.

    1995-06-01

    In order to mitigate the reappearance of the HOM wakefield of a detuned accelerator structure and relax tolerance requirements, we propose to provide low level damping by coupling all cavities to several identical and symmetrically located waveguides (manifolds) which run parallel to each accelerator structure and are terminated at each end by matched loads. The waveguides are designed such that all modes which couple to the acceleration mode are non-propagating at the acceleration mode frequency. Hence the coupling irises can be designed to provide large coupling to higher frequency modes without damping the acceleration mode. Because the higher order modes are detuned, they are localized and have a broad spectrum of phase velocities of both signs. They are therefore capable of coupling effectively to all propagating modes in the waveguides. Methods of analyzing and results obtained for the very complex system of modes in the accelerating structure and manifolds are presented.

  8. Manifold damping of the NLC detuned accelerating structure

    SciTech Connect

    Kroll, N.; Thompson, K.; Bane, K.; Ko, K.; Miller, R.; Ruth, R.; Gluckstern, R.

    1994-09-01

    In order to investigate the reappearance of the HOM wakefield of a detuned accelerator structure and relax tolerance requirements, we propose to provide low level damping by coupling all cavities to several identical and symmetrically located waveguides (manifolds) which run parallel to each accelerator structure and are terminated at each end by matched loads. The waveguides are designed such that all modes which couple to the acceleration mode are non-propagating at the acceleration mode frequency. Hence the coupling irises can be designed to provide large coupling to higher frequency modes without damping the acceleration mode. Because the higher order modes are detuned, they are localized and have a broad spectrum of phase velocities of both signs. They are therefore capable of coupling effectively to all propagating modes in the waveguides. Methods of analyzing and results obtained for the very complex system of modes in the accelerating structure and manifolds are presented.

  9. Interactive Troubleshooting Guide for Accelerators

    NASA Astrophysics Data System (ADS)

    Legg, Robert; Dunham, Bruce; Higgins, Scott; Kazimi, Reza; Kehne, David; Oren, Thomas

    1997-05-01

    Modern accelerators face the challenge of supporting increased machine complexity and higher levels of utilization while relying on downsized maintenance and support groups. To improve system availability, reduce reliance on system experts and provide a systematic approach to problem solving, an interactive troubleshooting system has been implemented for the CEBAF injector at Jefferson Lab. The guide uses a tree structure with hypertext links to trace problems from a set of symptoms through a series of diagnostic tests to a specific corrective action. This guide is used in conjunction with an active parameter monitoring system, which is part of the EPICS control system tool kit, which generates operator alarms when injector rf or magnet parameters fall outside pre-set windows. In this way, operators are given immediate feedback when injector components vary from their standard values and a systematic guide is provided on how to correct the problem.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Radioisotope Dating with Accelerators.

    ERIC Educational Resources Information Center

    Muller, Richard A.

    1979-01-01

    Explains a new method of detecting radioactive isotopes by counting their accelerated ions rather than the atoms that decay during the counting period. This method increases the sensitivity by several orders of magnitude, and allows one to find the ages of much older and smaller samples. (GA)

  17. Accelerated Management Development

    ERIC Educational Resources Information Center

    Munn, Kenn

    1974-01-01

    Western Electric's accelerated management development program for hand picked college graduate students consists of a high risk training project in which the management candidate accomplishes his task or is terminated. The success of such projects puts candidates in third level management in seven years or half the normal time. (DS)

  18. FPGA Verification Accelerator (FVAX)

    NASA Technical Reports Server (NTRS)

    Oh, Jane; Burke, Gary

    2008-01-01

    Is Verification Acceleration Possible? - Increasing the visibility of the internal nodes of the FPGA results in much faster debug time - Forcing internal signals directly allows a problem condition to be setup very quickly center dot Is this all? - No, this is part of a comprehensive effort to improve the JPL FPGA design and V&V process.

  19. Combined generating-accelerating buncher for compact linear accelerators

    NASA Astrophysics Data System (ADS)

    Savin, E. A.; Matsievskiy, S. V.; Sobenin, N. P.; Sokolov, I. D.; Zavadtsev, A. A.

    2016-09-01

    Described in the previous article [1] method of the power extraction from the modulated electron beam has been applied to the compact standing wave electron linear accelerator feeding system, which doesnt require any connection waveguides between the power source and the accelerator itself [2]. Generating and accelerating bunches meet in the hybrid accelerating cell operating at TM020 mode, thus the accelerating module is placed on the axis of the generating module, which consists from the pulsed high voltage electron sources and electrons dumps. This combination makes the accelerator very compact in size which is very valuable for the modern applications such as portable inspection sources. Simulations and geometry cold tests are presented.

  20. 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%.

  1. Plasma acceleration above martian magnetic anomalies.

    PubMed

    Lundin, R; Winningham, D; Barabash, S; Frahm, R; Holmström, M; Sauvaud, J-A; Fedorov, A; Asamura, K; Coates, A J; Soobiah, Y; Hsieh, K C; Grande, M; Koskinen, H; Kallio, E; Kozyra, J; Woch, J; Fraenz, M; Brain, D; Luhmann, J; McKenna-Lawler, S; Orsini, R S; Brandt, P; Wurz, P

    2006-02-17

    Auroras are caused by accelerated charged particles precipitating along magnetic field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal magnetization regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging magnetic flux tubes above crustal magnetization regions, the auroras being distributed geographically in a complex pattern by the many multipole magnetic field lines extending into space.

  2. Neurodegeneration in accelerated aging.

    PubMed

    Scheibye-Knudsen, Moren

    2016-11-01

    The growing proportion of elderly people represents an increasing economic burden, not least because of age-associated diseases that pose a significant cost to the health service. Finding possible interventions to age-associated disorders therefore have wide ranging implications. A number of genetically defined accelerated aging diseases have been characterized that can aid in our understanding of aging. Interestingly, all these diseases are associated with defects in the maintenance of our genome. A subset of these disorders, Cockayne syndrome, Xeroderma pigmentosum group A and ataxia-telangiectasia, show neurological involvement reminiscent of what is seen in primary human mitochondrial diseases. Mitochondria are the power plants of the cells converting energy stored in oxygen, sugar, fat, and protein into ATP, the energetic currency of our body. Emerging evidence has linked this organelle to aging and finding mitochondrial dysfunction in accelerated aging disorders thereby strengthens the mitochondrial theory of aging. This theory states that an accumulation of damage to the mitochondria may underlie the process of aging. Indeed, it appears that some accelerated aging disorders that show neurodegeneration also have mitochondrial dysfunction. The mitochondrial alterations may be secondary to defects in nuclear DNA repair. Indeed, nuclear DNA damage may lead to increased energy consumption, alterations in mitochondrial ATP production and defects in mitochondrial recycling, a term called mitophagy. These changes may be caused by activation of poly-ADP-ribose-polymerase 1 (PARP1), an enzyme that responds to DNA damage. Upon activation PARP1 utilizes key metabolites that attenuate pathways that are normally protective for the cell. Notably, pharmacological inhibition of PARP1 or reconstitution of the metabolites rescues the changes caused by PARP1 hyperactivation and in many cases reverse the phenotypes associated with accelerated aging. This implies that modulation

  3. Menopause accelerates biological aging

    PubMed Central

    Levine, Morgan E.; Lu, Ake T.; Chen, Brian H.; Hernandez, Dena G.; Singleton, Andrew B.; Ferrucci, Luigi; Bandinelli, Stefania; Salfati, Elias; Manson, JoAnn E.; Quach, Austin; Kusters, Cynthia D. J.; Kuh, Diana; Wong, Andrew; Teschendorff, Andrew E.; Widschwendter, Martin; Ritz, Beate R.; Absher, Devin; Assimes, Themistocles L.; Horvath, Steve

    2016-01-01

    Although epigenetic processes have been linked to aging and disease in other systems, it is not yet known whether they relate to reproductive aging. Recently, we developed a highly accurate epigenetic biomarker of age (known as the “epigenetic clock”), which is based on DNA methylation levels. Here we carry out an epigenetic clock analysis of blood, saliva, and buccal epithelium using data from four large studies: the Women's Health Initiative (n = 1,864); Invecchiare nel Chianti (n = 200); Parkinson's disease, Environment, and Genes (n = 256); and the United Kingdom Medical Research Council National Survey of Health and Development (n = 790). We find that increased epigenetic age acceleration in blood is significantly associated with earlier menopause (P = 0.00091), bilateral oophorectomy (P = 0.0018), and a longer time since menopause (P = 0.017). Conversely, epigenetic age acceleration in buccal epithelium and saliva do not relate to age at menopause; however, a higher epigenetic age in saliva is exhibited in women who undergo bilateral oophorectomy (P = 0.0079), while a lower epigenetic age in buccal epithelium was found for women who underwent menopausal hormone therapy (P = 0.00078). Using genetic data, we find evidence of coheritability between age at menopause and epigenetic age acceleration in blood. Using Mendelian randomization analysis, we find that two SNPs that are highly associated with age at menopause exhibit a significant association with epigenetic age acceleration. Overall, our Mendelian randomization approach and other lines of evidence suggest that menopause accelerates epigenetic aging of blood, but mechanistic studies will be needed to dissect cause-and-effect relationships further. PMID:27457926

  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. Stacked insulator induction accelerator gaps

    SciTech Connect

    Houck, T.I.; Westenskow, G.A.; Kim, J.S.; Eylon, S.; Henestroza, E.; Yu, S.S.; Vanecek, D.

    1997-05-01

    Stacked insulators, with alternating layers of insulating material and conducting film, have been shown to support high surface electrical field stresses. We have investigated the application of the stacked insulator technology to the design of induction accelerator modules for the Relativistic-Klystron Two-Beam Accelerator program. The rf properties of the accelerating gaps using stacked insulators, particularly the impedance at frequencies above the beam pipe cutoff frequency, are investigated. Low impedance is critical for Relativistic-Klystron Two-Beam Accelerator applications where a high current, bunched beam is trsnsported through many accelerating gaps. An induction accelerator module designs using a stacked insulator is presented.

  6. Mass spectrometry with accelerators.

    PubMed

    Litherland, A E; Zhao, X-L; Kieser, W E

    2011-01-01

    As one in a series of articles on Canadian contributions to mass spectrometry, this review begins with an outline of the history of accelerator mass spectrometry (AMS), noting roles played by researchers at three Canadian AMS laboratories. After a description of the unique features of AMS, three examples, (14)C, (10)Be, and (129)I are given to illustrate the methods. The capabilities of mass spectrometry have been extended by the addition of atomic isobar selection, molecular isobar attenuation, further ion acceleration, followed by ion detection and ion identification at essentially zero dark current or ion flux. This has been accomplished by exploiting the techniques and accelerators of atomic and nuclear physics. In 1939, the first principles of AMS were established using a cyclotron. In 1977 the selection of isobars in the ion source was established when it was shown that the (14)N(-) ion was very unstable, or extremely difficult to create, making a tandem electrostatic accelerator highly suitable for assisting the mass spectrometric measurement of the rare long-lived radioactive isotope (14)C in the environment. This observation, together with the large attenuation of the molecular isobars (13)CH(-) and (12)CH 2(-) during tandem acceleration and the observed very low background contamination from the ion source, was found to facilitate the mass spectrometry of (14)C to at least a level of (14)C/C ~ 6 × 10(-16), the equivalent of a radiocarbon age of 60,000 years. Tandem Accelerator Mass Spectrometry, or AMS, has now made possible the accurate radiocarbon dating of milligram-sized carbon samples by ion counting as well as dating and tracing with many other long-lived radioactive isotopes such as (10)Be, (26)Al, (36)Cl, and (129)I. The difficulty of obtaining large anion currents with low electron affinities and the difficulties of isobar separation, especially for the heavier mass ions, has prompted the use of molecular anions and the search for alternative

  7. 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.

  8. FFAGs: Front-end for neutrino factories and medical accelerators

    NASA Astrophysics Data System (ADS)

    Mori, Yoshiharu

    The idea of Fixed Field Alternating Gradient (FFAG) accelerator was originated by different people and groups in the early 1950s. It was independently introduced by Ohkawa [Ohkawa (1953)], Symon et al. [Symon et al. (1956)], and Kolomensky [Kolomensky and Lebedev (1966)] when the strong Alternate Gradient (AG) focusing and the phase stability schemes were applied to particle acceleration. The first FFAG electron model was developed in the MURA accelerator project led by Kerst and Cole in the late 1950s. Since then, they have fabricated several electron models in the early 1960s [Symon et al. (1956)]. However, the studies did not lead to a single practical FFAG accelerator for the following 50 years. Because of the difficulties of treating non-linear magnetic field and RF acceleration for non-relativistic particles, the proton FFAG, especially, was not accomplished until recently. In 2000, the FFAG concept was revived with the world's first proton FFAG (POP) which was developed at KEK [Aiba (2000); Mori (1999)]. Since then, in many places [Berg (2004); Johnstone et al. (2004); Mori (2011); Ruggiero (2004); Trbojevic (2004)], FFAGs have been developed and constructed...

  9. Surface plasmon resonance in nanostructured Ag incorporated ZnS films

    NASA Astrophysics Data System (ADS)

    Chalana, S. R.; Ganesan, V.; Mahadevan Pillai, V. P.

    2015-10-01

    Silver incorporated zinc sulfide thin films are prepared by RF magnetron sputtering technique and the influence of silver incorporation on the structural, optical and luminescence properties is analyzed using techniques like grazing incidence X-Ray diffraction (GIXRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), micro-Raman spectroscopy, UV-Vis spectroscopy and laser photoluminescence spectroscopy. XRD analysis presents hexagonal wurtzite structure for the films. A reduction of crystallinity of the films is observed due to Ag incorporation. The Raman spectral analysis confirms the reduction of crystallinity and increase of strain due to the Ag incorporation. AFM analysis reveals a rough surface morphology for the undoped film and Ag incorporation makes the films uniform, dense and smooth. A blue shift of band gap energy with increase in Ag incorporation is observed due to quantum confinement effect. An absorption band (450-650 nm region) due to surface plasmon resonance of the Ag clusters present in the ZnS matrix is observed for the samples with higher Ag incorporation. The complex dielectric constant, loss factor and distribution of volume and surface energy loss of the ZnS thin films are calculated. Laser photoluminescence measurements gives an intense bluish green emission from the ZnS films and a quenching of the PL emission is observed which can be due to the metal plasmonic absorption and non-radiative energy transfer due to Ag incorporation.

  10. Surface plasmon resonance in nanostructured Ag incorporated ZnS films

    SciTech Connect

    Chalana, S. R.; Mahadevan Pillai, V. P.; Ganesan, V.

    2015-10-15

    Silver incorporated zinc sulfide thin films are prepared by RF magnetron sputtering technique and the influence of silver incorporation on the structural, optical and luminescence properties is analyzed using techniques like grazing incidence X-Ray diffraction (GIXRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), micro-Raman spectroscopy, UV-Vis spectroscopy and laser photoluminescence spectroscopy. XRD analysis presents hexagonal wurtzite structure for the films. A reduction of crystallinity of the films is observed due to Ag incorporation. The Raman spectral analysis confirms the reduction of crystallinity and increase of strain due to the Ag incorporation. AFM analysis reveals a rough surface morphology for the undoped film and Ag incorporation makes the films uniform, dense and smooth. A blue shift of band gap energy with increase in Ag incorporation is observed due to quantum confinement effect. An absorption band (450-650 nm region) due to surface plasmon resonance of the Ag clusters present in the ZnS matrix is observed for the samples with higher Ag incorporation. The complex dielectric constant, loss factor and distribution of volume and surface energy loss of the ZnS thin films are calculated. Laser photoluminescence measurements gives an intense bluish green emission from the ZnS films and a quenching of the PL emission is observed which can be due to the metal plasmonic absorption and non-radiative energy transfer due to Ag incorporation.

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

    PubMed

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

    2014-01-15

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

  12. Highly active Ag clusters stabilized on TiO2 nanocrystals for catalytic reduction of p-nitrophenol

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Zhao, Zhe; Ou, Dingrong; Tu, Baofeng; Cui, Daan; Wei, Xuming; Cheng, Mojie

    2016-11-01

    Ag/TiO2 nanocomposites comprising of Ag clusters on TiO2 nanocrystal surfaces are of great significance in catalysts and advanced functional materials. Herein a novel method to synthesize Ag/TiO2 nanocomposites with Ag clusters under 2 nm on TiO2 nanocrystal surfaces have been developed. The success of this method relies on a silver mirror reaction in toluene, which refers to the reduction of silver-dodecylamine complexes by acetaldehyde in the presence of mono-dispersed TiO2 nanocrystals. The prepared Ag/TiO2 nanocomposites have been characterized by FT-IR spectra, UV-vis absorption spectra, X-ray diffraction (XRD) analysis, ultra high resolution scanning electron microscope (Ultra-HRSEM), high resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectra (XPS). Catalytic activity of Ag/TiO2 nanocomposites is evaluated for the reduction of p-nitrophenol (4-NP) into p-aminophenol (4-AP) by NaBH4. Results demonstrate that Ag/TiO2 nanocomposites have shown an outstanding catalytic activity as well as a good stability in successive reduction of 4-NP. Noticeably, TOF of Ag/TiO2-0.75 nanocomposites obtained in this work is the highest among Ag based catalysts previously reported.

  13. Nonparaxial Near-Nondiffracting Accelerating Optical Beams

    NASA Astrophysics Data System (ADS)

    Lai, Ru-Yu; Zhou, Ting

    2017-02-01

    We show that new families of accelerating and almost nondiffracting beams (solutions) for Maxwell's equations can be constructed. These are complex geometrical optics (CGO) solutions to Maxwell's equations with nonlinear limiting Carleman weights. They have the form of wave packets that propagate along circular trajectories while almost preserving a transverse intensity profile. We also show similar waves constructed using the approach combining CGO solutions and the Kelvin transform.

  14. Non-cytotoxic antibacterial silver-coumarin complex doped sol-gel coatings.

    PubMed

    Jaiswal, Swarna; Bhattacharya, Kunal; Sullivan, Maeve; Walsh, Maureen; Creaven, Bernadette S; Laffir, Fathima; Duffy, Brendan; McHale, Patrick

    2013-02-01

    Microbial colonisation on clinical and industrial surfaces is currently of global concern and silane based sol-gel coatings are being proposed as potential solutions. Sol-gels are chemically inert, stable and homogeneous and can be designed to act as a reservoir for releasing antimicrobial agents over extended time periods. In the present study, silver nitrate (AgN) and a series of silver coumarin complexes based on coumarin-3-carboxylatosilver (AgC) and it is 6, 7 and 8 hydroxylated analogues (Ag6, Ag7, Ag8) were incorporated into sol-gel coatings. The comparative antibacterial activity of the coatings was determined against meticillin resistant Staphylococcus aureus (MRSA) and multidrug resistance Enterobacter cloacae WT6. The percentage growth inhibitions were found in the range of 9.2 (±2.7)-66.0 (±1.2)% at low silver loadings of 0.3% (w/w) with E. cloacae being the more susceptible. Results showed that among the Ag coumarin complexes, the Ag8 doped coating had the highest antibiofilm property. XPS confirmed the presence of silver in the nanoparticulate state (Ag(0)) at the coating surface where it remained after 4 days of exposure to bacterial culture. Comparative cytotoxicity studies revealed that the Ag-complex coatings were less toxic than the AgN coating. Thus, it can be concluded that a sol-gel matrix with Ag-coumarin complexes may provide non-toxic surfaces with antibacterial properties.

  15. Review of ion accelerators

    SciTech Connect

    Alonso, J.

    1990-06-01

    The field of ion acceleration to higher energies has grown rapidly in the last years. Many new facilities as well as substantial upgrades of existing facilities have extended the mass and energy range of available beams. Perhaps more significant for the long-term development of the field has been the expansion in the applications of these beams, and the building of facilities dedicated to areas outside of nuclear physics. This review will cover many of these new developments. Emphasis will be placed on accelerators with final energies above 50 MeV/amu. Facilities such as superconducting cyclotrons and storage rings are adequately covered in other review papers, and so will not be covered here.

  16. Accelerator research studies

    SciTech Connect

    Not Available

    1992-01-01

    The Accelerator Research Studies program at the University of Maryland, sponsored by the Department of Energy under grant number DE-FG05-91ER40642, is currently in the first year of a three-year funding cycle. The program consists of the following three tasks: TASK A, Study of Transport and Longitudinal Compression of Intense, High-Brightness Beams, TASK B, Study of Collective Ion Acceleration by Intense Electron Beams and Pseudospark Produced High Brightness Electron Beams; TASK C, Study of a Gyroklystron High-power Microwave Source for Linear Colliders. In this report we document the progress that has been made during the past year for each of the three tasks.

  17. Commissioning the GTA accelerator

    SciTech Connect

    Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V.; Connolly, R.; Weiss, R.; Saadatmand, K.

    1992-09-01

    The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth`s magnetic field and travel in straight lines unless they enter the earth`s atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -} beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.

  18. Commissioning the GTA accelerator

    SciTech Connect

    Sander, O.R.; Atkins, W.H.; Bolme, G.O.; Bowling, S.; Brown, S.; Cole, R.; Gilpatrick, J.D.; Garnett, R.; Guy, F.W.; Ingalls, W.B.; Johnson, K.F.; Kerstiens, D.; Little, C.; Lohsen, R.A.; Lloyd, S.; Lysenko, W.P.; Mottershead, C.T.; Neuschaefer, G.; Power, J.; Rusthoi, D.P.; Sandoval, D.P. Stevens, R.R. Jr.; Vaughn, G.; Wadlinger, E.A.; Yuan, V. ); Connolly, R.; Weiss, R. (Gr

    1992-01-01

    The Ground Test Accelerator (GTA) is supported by the Strategic Defense command as part of their Neutral Particle Beam (NPB) program. Neutral particles have the advantage that in space they are unaffected by the earth's magnetic field and travel in straight lines unless they enter the earth's atmosphere and become charged by stripping. Heavy particles are difficult to stop and can probe the interior of space vehicles; hence, NPB can function as a discriminator between warheads and decoys. We are using GTA to resolve the physics and engineering issues related to accelerating, focusing, and steering a high-brightness, high-current H{sup -} beam and then neutralizing it. Our immediate goal is to produce a 24-MeV, 50mA device with a 2% duty factor.

  19. Auroral ion acceleration

    NASA Astrophysics Data System (ADS)

    Shalimov, S. L.

    From the altitude of 500 km to 15 R sub E everywhere conic like distributions of H+, O+, He+ ions are moving upwards from the ionosphere along the geomagnetic field lines in the auroral zone. The distributed ions suggest the existence of ion transverse acceleration mechanisms (ITAM) acting below the observation point. The more plausible mechanisms are connected with the resonance of the type wave particle between ions and the observed EIC and LH waves and are also due to the existence of the local transverse electric fields in the ionoshere and the magnetosphere. The known ion transverse acceleration mechanisms were complemented by new results. The conical distributions of ionospheric ions at different altitudes in the auroral zone are pointed out.

  20. Review of accelerator instrumentation

    SciTech Connect

    Pellegrin, J.L.

    1980-05-01

    Some of the problems associated with the monitoring of accelerator beams, particularly storage rings' beams, are reviewed along with their most common solutions. The various electrode structures used for the measurement of beam current, beam position, and the detection of the bunches' transverse oscillations, yield pulses with sub-nanosecond widths. The electronics for the processing of these short pulses involves wide band techniques and circuits usually not readily available from industry or the integrated circuit market: passive or active, successive integrations, linear gating, sample-and-hold circuits with nanosecond acquisition time, etc. This report also presents the work performed recently for monitoring the ultrashort beams of colliding linear accelerators or single-pass colliders. To minimize the beam emittance, the beam position must be measured with a high resolution, and digitized on a pulse-to-pulse basis. Experimental results obtained with the Stanford two-mile Linac single bunches are included.