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Sample records for bi-in bi-mg bi-sb

  1. Lattice thermal conductivity of Bi, Sb, and Bi-Sb alloy from first principles

    NASA Astrophysics Data System (ADS)

    Lee, Sangyeop; Esfarjani, Keivan; Mendoza, Jonathan; Dresselhaus, Mildred S.; Chen, Gang

    2014-02-01

    Using first principles, we calculate the lattice thermal conductivity of Bi, Sb, and Bi-Sb alloys, which are of great importance for thermoelectric and thermomagnetic cooling applications. Our calculation reveals that the ninth-neighbor harmonic and anharmonic force constants are significant; accordingly, they largely affect the lattice thermal conductivity. Several features of the thermal transport in these materials are studied: (1) the relative contributions from phonons and electrons to the total thermal conductivity as a function of temperature are estimated by comparing the calculated lattice thermal conductivity to the measured total thermal conductivity, (2) the anisotropy of the lattice thermal conductivity is calculated and compared to that of the electronic contribution in Bi, and (3) the phonon mean free path distributions, which are useful for developing nanostructures to reduce the lattice thermal conductivity, are calculated. The phonon mean free paths are found to range from 10 to 100 nm for Bi at 100 K.

  2. Mechanical alloying of BiTe and BiSbTe thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Hasezaki, K.; Nishimura, M.; Umata, M.; Tsukuda, H.; Araoka, M.

    1994-06-01

    Two thermoelectric materials, BiTe and BiSbTe were prepared by mechanical attrition of elemental powders in a rare gas atmosphere. Nearly 20 min were required for the alloying of BiTe, while 10 h were required for BiSbTe. After attrition, the average powder diameter of the BiSbTe alloy was in 1.4 micron, and the impurity content, measured by Inductively Coupled Argon Plasma Emission Spectrophotometer, was less than 0.1 mass%. The MA powders were sintered by a hot pressing technique. Uniform elemental dispersions were measured by EPMA in BiSbTe alloys sintered at 623 K.

  3. BiSb and spin-related thermoelectric phenomena

    NASA Astrophysics Data System (ADS)

    Heremans, Joseph P.; Jin, Hyungyu; Zheng, Yuanhua; Watzman, Sarah J.; Prakash, Arati

    2016-05-01

    This article reviews the factors limiting the figure of merit zT of conventional thermoelectrics especially at cryogenic temperatures and then highlights modern approaches used to increase zT below 200 K. Two type of materials are discussed. The first are BiSb alloys, relatively conventional thermoelectrics in which the zT is enhanced by using resonant levels. The second is the spin- Seebeck effect (SSE), a new solid-state energy conversion technology. Classical thermoelectric and SSE physics are combined to provide new concepts, like magnon-drag, in which we hope to increase the performance of solid-state coolers by exploiting the spin degree of freedom.

  4. Optical properties and electronic band structure of BiMg2PO6, BiMg2VO6, BiMg2VO6:Pr3+ and BiMg2VO6:Eu3+

    NASA Astrophysics Data System (ADS)

    Barros, A.; Deloncle, R.; Deschamp, J.; Boutinaud, P.; Chadeyron, G.; Mahiou, R.; Cavalli, E.; Brik, M. G.

    2014-08-01

    The luminescence properties of the yellow pigment BiMg2VO6 are revisited and those of BiMg2PO6, BiMg2VO6:Pr3+ and BiMg2VO6:Eu3+ are described. It is shown that the undoped systems exhibit broad band emission in the green or orange spectral regions, but only upon UV or near UV excitation. In contradiction with a previous report, we found that the blue, host absorbed, photons are lost non-radiatively and do not contribute to the luminescence processes in BiMg2VO6. To understand these experimental results, the optical properties of BiMg2VO6 and BiMg2PO6 are theoretically analysed on the basis of electronic structure diagrams calculated by the DFT method. It is found that the optical transitions are mostly localised within [VO4]3- units or non-regular Bi3+ ions and occur in the UV or near UV regions. The luminescence of the trivalent lanthanide dopants is weak (Eu3+) or unobserved (Pr3+) in BiMg2VO6 which is explained by inefficient energy migration in the host lattice to the impurity sites.

  5. Crystal structure and dielectric properties of ordered perovskites Ba 2BiSbO 6 and BaSrBiSbO 6

    NASA Astrophysics Data System (ADS)

    Mangalam, R. V. K.; Suard, E.; Sundaresan, A.

    2009-01-01

    Neutron powder diffraction studies showed that the ordered perovskites Ba 2BiSbO 6 (BBS) and BaSrBiSbO 6 (BSBS) crystallize in a rhombohedral structure with the space group R3bar. The room-temperature lattice parameters are a=6.0351(2) Å; α=60.202(1)° and a=5.9809(2) Å; α=60.045(2)°, respectively. BBS exhibits a dielectric anomaly near room temperature which may be related to structural transition from the R3bar to low-temperature monoclinic I2/m symmetry. BSBS shows a dielectric anomaly near 723 K which coincides with a phase transition from the rhombohedral to cubic (Fm3barm) structure. In contrast to BBS, BSBS does not undergo structural transition below room temperature.

  6. High-Pressure Crystal Structure, Lattice Vibrations, and Band Structure of BiSbO4.

    PubMed

    Errandonea, Daniel; Muñoz, Alfonso; Rodríguez-Hernández, Placida; Gomis, Oscar; Achary, S Nagabhusan; Popescu, Catalin; Patwe, Sadeque J; Tyagi, Avesh K

    2016-05-16

    The high-pressure crystal structure, lattice-vibrations, and electronic band structure of BiSbO4 were studied by ab initio simulations. We also performed Raman spectroscopy, infrared spectroscopy, and diffuse-reflectance measurements, as well as synchrotron powder X-ray diffraction. High-pressure X-ray diffraction measurements show that the crystal structure of BiSbO4 remains stable up to at least 70 GPa, unlike other known MTO4-type ternary oxides. These experiments also give information on the pressure dependence of the unit-cell parameters. Calculations properly describe the crystal structure of BiSbO4 and the changes induced by pressure on it. They also predict a possible high-pressure phase. A room-temperature pressure-volume equation of state is determined, and the effect of pressure on the coordination polyhedron of Bi and Sb is discussed. Raman- and infrared-active phonons were measured and calculated. In particular, calculations provide assignments for all the vibrational modes as well as their pressure dependence. In addition, the band structure and electronic density of states under pressure were also calculated. The calculations combined with the optical measurements allow us to conclude that BiSbO4 is an indirect-gap semiconductor, with an electronic band gap of 2.9(1) eV. Finally, the isothermal compressibility tensor for BiSbO4 is given at 1.8 GPa. The experimental (theoretical) data revealed that the direction of maximum compressibility is in the (0 1 0) plane at ∼33° (38°) to the c-axis and 47° (42°) to the a-axis. The reliability of the reported results is supported by the consistency between experiments and calculations. PMID:27128858

  7. Synthesis, Characterization and Photocatalytic Activity of New Photocatalyst ZnBiSbO4 under Visible Light Irradiation

    PubMed Central

    Luan, Jingfei; Chen, Mengjing; Hu, Wenhua

    2014-01-01

    In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. PMID:24879521

  8. Evidence for surface-generated photocurrent in (Bi,Sb)2Se3and(Bi,Sb)2Te3 thin films

    NASA Astrophysics Data System (ADS)

    Pan, Yu; Richardella, Anthony; Yao, Bing; Lee, Joon Sue; Flanagan, Thomas; Kandala, Abhinav; Samarth, Nitin; Yeats, Andrew; Mintun, Peter; Awschalom, David

    2015-03-01

    Illumination with circularly polarized light is known produce a helicity-dependent photocurrent in topological insulators such as Bi2Se3 [e.g. Nature Nanotech. 7, 96 (2012)]. However, the exact origin of this effect is still unclear since it is observed with photons well above the bulk band gap. We report measurements of the polarization-dependent photocurrent in a series of (Bi,Sb)2Se3 thin films with different carrier concentrations and find that the photocurrent is enhanced as we increase the population of the surface states. This finding is supported by a study of helicity-dependent photocurrents in back-gated (Bi,Sb)2Te3 thin films, where the chemical potential is varied electrostatically. By illuminating our samples at different wavelengths, we show that the helicity-dependent photocurrent is enhanced when the photon energy approaches the energy difference between the lowest and first excited (unoccupied) topological surface states. This leads us to attribute the helicity-dependent photocurrent in topological insulators to optical excitations between these two spin-textured surface states. We will also discuss experiments imaging the spatial variation of these helicity-dependent photocurrents. This work is supported by ONR.

  9. Synthesis and Characterization of Bismuth Magnesium Phosphate and Arsenate: BiMg 2PO 6 and BiMg 2AsO 6

    NASA Astrophysics Data System (ADS)

    Huang, Jinfan; Gu, Qiuyi; Sleight, Arthur W.

    1993-08-01

    Two new compounds, BiMg 2PO 6 and BiMg 2AsO 6, have been synthesized and structurally characterized by single crystal and powder X-ray diffraction. Both compounds crystallize in the orthorhombic space group Cmcm (No. 63) with four formula units per unit cell. They are isostructural with bismuth magnesium vanadate, BiMg 2VO 6. The cell parameters for BiMg 2PO 6 are a = 7.801(2), b = 11.888(3), c = 5.273(2) Å, V = 489.0(2) Å 3 and for BiMg 2AsO 6 are a = 7.9142(5), b = 12.1637(8), c = 5.3898(4) Å, V = 518.9(2) Å 3. The formula for this series of compounds may be written as (BiO 2)Mg AO 4 to emphasize the (BiO 2) 1- chains and the (AO 4) 3- tetrahedral groups isolated from one another. Between these chains and tetrahedral groups sit Mg 2+ cations in an unusual fivefold coordination to oxygen. No emission bands were observed from BiMg 2PO 6 and BiMg 2AsO 6 under excitation with UV or visible radiation. The IR spectra of these compounds are compared to that of BiMg 2VO 6.

  10. Study of the circular photo-galvanic effect in electrically gated (Bi,Sb)2Te3 thin films

    NASA Astrophysics Data System (ADS)

    Pan, Yu; Pillsbury, Timothy; Richardella, Anthony; Flanagan, Thomas; Samarth, Nitin

    Illumination with circularly polarized light is known to produce a helicity dependent photocurrent in topological insulators such as Bi2Se3 [Nature Nanotech. 7, 96 (2012)]. Symmetry considerations suggest that this ``circular photo-galvanic effect'' (CPGE) arises purely from the surface. However, whether or not the CPGE is directly related to optical excitations from the helical surface states is still under debate. To clarify the origin of the CPGE, we first compare the helicity dependent photocurrent in intrinsic (Bi,Sb)2Te3 to Cr doped (Bi,Sb)2Te3 thin films in which the Dirac surface states are perturbed by magnetic coupling. Secondly, we discuss the tunable CPGE in electrically gated (Bi,Sb)2Te3 thin films excited by optical excitations at different wavelengths. The dependence on the chemical potential and the photon energy of the excitation unveils the origin of the CPGE. Funded by ONR.

  11. Influence of Sedimentation of Atoms on Structural and Thermoelectric Properties of Bi-Sb Alloys

    NASA Astrophysics Data System (ADS)

    Januszko, Kamila; Stabrawa, Artur; Ogata, Yudai; Tokuda, Makoto; Khandaker, Jahirur Islam; Wojciechowski, Krzysztof; Mashimo, Tsutomu

    2016-03-01

    Functionally graded thermoelectric materials (FGTMs) have been prepared by sedimentation of atoms under a strong gravitational field. Starting samples of Bi x Sb1- x alloys with different composition x were synthesized by melting of metals and subsequent annealing of quenched samples. The thermoelectric properties (Seebeck coefficient, electrical conductivity) of the starting materials were characterized over the temperature range from 300 K to 525 K. Strong gravity experiments were performed in a unique ultracentrifuge apparatus under acceleration of over 0.5 × 106 G at temperatures of 538 K and 623 K. Changes of the microstructure and chemical composition were analyzed using scanning electron microscopy with energy-dispersive x-ray spectroscopy analysis. The distribution of the Seebeck coefficient of the Bi-Sb alloys was characterized by scanning thermoelectric microprobe. As a result of sedimentation, large changes in chemical composition ( x = 0.45 to 1) were obtained. It was found that the changes in chemical composition were correlated with alterations of the Seebeck coefficient. The obtained experimental data allowed the development of a semiempirical model for the selection of optimal processing parameters for preparation of Bi-Sb alloys with required thermoelectric properties.

  12. Homologous series of layered structures in binary and ternary Bi-Sb-Te-Se systems: Ab initio study

    NASA Astrophysics Data System (ADS)

    Govaerts, K.; Sluiter, M. H. F.; Partoens, B.; Lamoen, D.

    2014-02-01

    In order to account explicitly for the existence of long-periodic layered structures and the strong structural relaxations in the most common binary and ternary alloys of the Bi-Sb-Te-Se system, we have developed a one-dimensional cluster expansion (CE) based on first-principles electronic structure calculations, which accounts for the Bi and Sb bilayer formation. Excellent interlayer distances are obtained with a van der Waals density functional. It is shown that a CE solely based on pair interactions is sufficient to provide an accurate description of the ground-state energies of Bi-Sb-Te-Se binary and ternary systems without making the data set of ab initio calculated structures unreasonably large. For the binary alloys A1-xQx (A =Sb, Bi; Q =Te, Se), a ternary CE yields an almost continuous series of (meta)stable structures consisting of consecutive A bilayers next to consecutive A2Q3 for 00.6, the binary alloy segregates into pure Q and A2Q3. The Bi-Sb system is described by a quaternary CE and is found to be an ideal solid solution stabilized by entropic effects at T ≠0 K but with an ordered structure of alternating Bi and Sb layers for x =0.5 at T =0 K. A quintuple CE is used for the ternary Bi-Sb-Te system, where stable ternary layered compounds with an arbitrary stacking of Sb2Te3,Bi2Te3, and Te-Bi-Te-Sb-Te quintuple units are found, optionally separated by mixed Bi/Sb bilayers. Electronic properties of the stable compounds were studied taking spin-orbit coupling into account.

  13. The properties of BiSb nanoribbons from first-principles calculations.

    PubMed

    Lv, H Y; Liu, H J; Tan, X J; Pan, L; Wen, Y W; Shi, J; Tang, X F

    2012-01-21

    The structural, electronic and magnetic properties of BiSb nanoribbons (BSNRs) with different widths and edge configurations are investigated via the first-principles pseudopotential method. It is found that the pristine BSNRs with armchair edges (ABSNRs) are semiconductors and the band gaps exhibit a width dependent odd-even oscillation. In contrast, the pristine BSNRs with zigzag edges (ZBSNRs) are found to be metallic. When all the edge atoms are passivated by hydrogen, both the ABSNRs and ZBSNRs become semiconducting and the corresponding band gaps decrease monotonically with the increasing width. If, however, the edge atoms are partially passivated, the ABSNRs can be either semiconducting or metallic. Moreover, local magnetism appears when all the edge Sb atoms are passivated and there are one or more unsaturated Bi atoms. Using the nonequilibrium Green's function (NEGF) approach, we find that all the investigated odd-numbered ABSNRs have almost the same peak value of the power factor around the Fermi level. This is not the case for the even-numbered ABSNRs, where the peaks are twice that of when they are n-type doped. Our calculations indicate that BSNRs can have a very high room temperature figure of merit (ZT value), which makes them very promising candidates for thermoelectric applications. PMID:22101571

  14. Using anodic aluminum oxide templates and electrochemical method to deposit BiSbTe-based thermoelectric nanowires

    PubMed Central

    2014-01-01

    In this study, the cyclic voltammetry method was first used to find the reduced voltages and anodic peaks of Bi3+, Sb3+, and Te4+ ions as the judgments for the growth of the (Bi,Sb)2 - x Te3 + x-based materials. Ethylene glycol (C2H6O2) was used as a solvent, and 0.3 M potassium iodide (KI) was used to improve the conductivity of the solution. Two different electrolyte formulas were first used: (a) 0.01 M Bi(NO3)3-5H2O, 0.01 M SbCl3, and 0.01 M TeCl4 and (b) 0.015 M Bi(NO3)3-5H2O, 0.005 M SbCl3, and 0.0075 M TeCl4. The potentiostatic deposition process was first used to find the effect of reduced voltage on the variation of compositions of the (Bi,Sb)2 - xTe3 + x-based materials. After finding the better reduced voltage, 0.01 M Bi(NO3)3-5H2O, 0.01 M SbCl3, and 0.01 M TeCl4 were used as the electrolyte formula. The pulse deposition process was successfully used to control the composition of the (Bi,Sb)2 - xTe3 + x-based materials and grow the nanowires in anodic aluminum oxide (AAO) templates. PMID:24502697

  15. The microstructure network and thermoelectric properties of bulk (Bi,Sb){sub 2}Te{sub 3}

    SciTech Connect

    Xie Wenjie; Hitchcock, Dale A.; Kang, Hye J.; He Jian; Tang Xinfeng; Laver, Mark; Hammouda, Boualem

    2012-09-10

    We report small-angle neutron scattering studies on the microstructure network in bulk (Bi,Sb){sub 2}Te{sub 3} synthesized by the melt-spinning (MS) and the spark-plasma-sintering (SPS) process. We find that rough interfaces of multiscale microstructures generated by the MS are responsible for the large reduction of both lattice thermal conductivity and electrical conductivity. Our study also finds that subsequent SPS forms a microstructure network of {approx}10 nm thick lamellae and smooth interfaces between them. This nanoscale microstructure network with smooth interfaces increases electrical conductivity while keeping a low thermal conductivity, making it an ideal microstructure for high thermoelectric efficiency.

  16. AlO x /LiF composite protection layer for Cr-doped (Bi,Sb)2Te3 quantum anomalous Hall films

    NASA Astrophysics Data System (ADS)

    Ou, Yunbo; Feng, Yang; Feng, Xiao; Hao, Zhenqi; Zhang, Liguo; Liu, Chang; Wang, Yayu; He, Ke; Ma, Xucun; Xue, Qikun

    2016-08-01

    We have realized robust quantum anomalous Hall samples by protecting Cr-doped (Bi,Sb)2Te3 topological insulator films with a combination of LiF and AlO x capping layers. The AlO x /LiF composite capping layer well keeps the quantum anomalous Hall states of Cr-doped (Bi,Sb)2Te3 films and effectively prevent them from degradation induced by ambient conditions. The progress is a key step towards the realization of the quantum phenomena in heterostructures and devices based on quantum anomalous Hall system. Project supported by the National Natural Science Foundation of China (Grant No. 11325421).

  17. Switching of charge-current-induced spin polarization in the topological insulator BiSbTeSe2

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Ghatak, Subhamoy; Taskin, A. A.; Segawa, Kouji; Ando, Yuichiro; Shiraishi, Masashi; Kanai, Yasushi; Matsumoto, Kazuhiko; Rosch, Achim; Ando, Yoichi

    2016-08-01

    The charge-current-induced spin polarization is a key property of topological insulators for their applications in spintronics. However, topological surface states are expected to give rise to only one type of spin polarization for a given current direction, which has been a limiting factor for spin manipulations. Here, we report that in devices based on the bulk-insulating topological insulator BiSbTeSe2, an unexpected switching of spin polarization was observed upon changing the chemical potential. The spin polarization expected from the topological surface states was detected in a heavily electron-doped device, whereas the opposite polarization was reproducibly observed in devices with low carrier densities. We propose that the latter type of spin polarization stems from topologically trivial two-dimensional states with a large Rashba spin splitting, which are caused by a strong band bending at the surface of BiSbTeSe2 beneath the ferromagnetic electrode used as a spin detector. This finding paves the way for realizing the "spin transistor" operation in future topological spintronic devices.

  18. First-principles study of homologous series of layered Bi-Sb-Te-Se and Sn-O structures

    NASA Astrophysics Data System (ADS)

    Govaerts, Kirsten

    In the first part of the thesis, we present a systematic study of the stable layered structures at T = 0 K for the Bi-Sb-Te-Se system by means of a combination of the Cluster Expansion (CE) method and first-principles electronic structure calculations. In order to account for the existence of long-periodic layered structures and the strong structural relaxations we have developed a one-dimensional CE with occupation variables explicitly accounting for the fact that Bi or Sb atoms are part of an even or odd number of layers. For the binary systems A1-xQx (A = Sb, Bi; Q = Te, Se) the resulting (meta)stable structures are the homologous series (A2) n(A2Q3)m built up from successive bilayers A 2 and quintuple units A2Q3. The Bi1-xSb x system is found to be an almost ideal solution. The CE for the ternary Bi-Sb-Te system not only reproduces the binary stable structures but also finds stable ternary layered compounds with an arbitrary stacking of Sb 2Te3, Bi2Te3 and Te-Bi-Te-Sb-Te quintuple units, optionally separated by mixed Bi/Sb bilayers. We also investigate the electronic properties of the newly found ground state structures, and in particular the effect of Bi bilayers on the electronic structure of the topological insulator Bi2Se3. Due to the charge transfer from the Bi bilayers to the quintuple layers, the top- and bottom-surface Dirac cones shift down in energy. Also the Rashba-split conduction band states shift down, resulting in a new Dirac cone. The bands of the additional Bi bilayer are just ordinary Rashba-split states originating from the dipole built up by the charge transfer. These results offer new insight in experimental results, where cones are not always correctly identified. In a second part of the thesis, we investigate the Sn-O system. First we show that a combination of current van der Waals-corrected functionals and many-body calculations within the GW approximation provide accurate values for both structural and electronic properties of Sn

  19. Terahertz Faraday Rotation in the Quantum Anomalous Hall System V-doped (Bi,Sb)2 Te3

    NASA Astrophysics Data System (ADS)

    Ozel, Ozge; Frenzel, Alex; Chang, Cui-Zu; Pilon, Daniel; Moodera, Jagadeesh; Gedik, Nuh; Gedik group Team; Moodera group Collaboration

    Time-reversal symmetry breaking in a topological insulator (TI) can be achieved by introducing ferromagnetism, which opens up a gap in the Dirac surface states. When the chemical potential is tuned to lie within the surface gap, the quantum anomalous Hall state emerges, which can be regarded as the quantum Hall state at zero external magnetic field. Recently, this state has been observed by static transport measurements in thin films of magnetically doped TIs. Time-domain terahertz spectroscopy has been demonstrated to be an effective probe of surface states and Hall effects in topological materials. Here, we use polarization modulation terahertz spectroscopy to study the intrinsic properties of massive Dirac electrons in V-doped (Bi,Sb)2Te3 via Faraday rotation measurements.

  20. Great enhancements in the thermoelectric power factor of BiSbTe nanostructured films with well-ordered interfaces.

    PubMed

    Chang, Hsiu-Cheng; Chen, Chun-Hua; Kuo, Yung-Kang

    2013-08-01

    An innovative concept of twin-enhanced thermoelectricity was proposed to fundamentally resolve the high electrical resistance while not degrading the phonon scattering of the thermoelectric nanoassemblies. Under this frame, a variety of highly oriented and twinned bismuth antimony telluride (BixSb2-xTe3) nanocrystals were successfully fabricated by a large-area pulsed-laser deposition (PLD) technique on insulated silicon substrates at various deposition temperatures. The significant presence of the nonbasal- and basal-plane twins across the hexagonal BiSbTe nanocrystals, which were experimentally and systematically observed for the first time, evidently contributes to the unusually high electrical conductivity of ~2700 S cm(-1) and the power factor of ~25 μW cm(-1) K(-2) as well as the relatively low thermal conductivity of ~1.1 W m(-1) K(-1) found in these nanostructured films. PMID:23803956

  1. Origin of the low critical observing temperature of the quantum anomalous Hall effect in V-doped (Bi, Sb)2Te3 film

    PubMed Central

    Li, W.; Claassen, M.; Chang, Cui-Zu; Moritz, B.; Jia, T.; Zhang, C.; Rebec, S.; Lee, J. J.; Hashimoto, M.; Lu, D.-H.; Moore, R. G.; Moodera, J. S.; Devereaux, T. P.; Shen, Z.-X.

    2016-01-01

    The experimental realization of the quantum anomalous Hall (QAH) effect in magnetically-doped (Bi, Sb)2Te3 films stands out as a landmark of modern condensed matter physics. However, ultra-low temperatures down to few tens of mK are needed to reach the quantization of Hall resistance, which is two orders of magnitude lower than the ferromagnetic phase transition temperature of the films. Here, we systematically study the band structure of V-doped (Bi, Sb)2Te3 thin films by angle-resolved photoemission spectroscopy (ARPES) and show unambiguously that the bulk valence band (BVB) maximum lies higher in energy than the surface state Dirac point. Our results demonstrate clear evidence that localization of BVB carriers plays an active role and can account for the temperature discrepancy. PMID:27599406

  2. Origin of the low critical observing temperature of the quantum anomalous Hall effect in V-doped (Bi, Sb)2Te3 film.

    PubMed

    Li, W; Claassen, M; Chang, Cui-Zu; Moritz, B; Jia, T; Zhang, C; Rebec, S; Lee, J J; Hashimoto, M; Lu, D-H; Moore, R G; Moodera, J S; Devereaux, T P; Shen, Z-X

    2016-01-01

    The experimental realization of the quantum anomalous Hall (QAH) effect in magnetically-doped (Bi, Sb)2Te3 films stands out as a landmark of modern condensed matter physics. However, ultra-low temperatures down to few tens of mK are needed to reach the quantization of Hall resistance, which is two orders of magnitude lower than the ferromagnetic phase transition temperature of the films. Here, we systematically study the band structure of V-doped (Bi, Sb)2Te3 thin films by angle-resolved photoemission spectroscopy (ARPES) and show unambiguously that the bulk valence band (BVB) maximum lies higher in energy than the surface state Dirac point. Our results demonstrate clear evidence that localization of BVB carriers plays an active role and can account for the temperature discrepancy. PMID:27599406

  3. Evolution of thermoelectric performance for (Bi,Sb)2Te3 alloys from cutting waste powders to bulks with high figure of merit

    NASA Astrophysics Data System (ADS)

    Fan, Xi‧an; Cai, Xin zhi; Han, Xue wu; Zhang, Cheng cheng; Rong, Zhen zhou; Yang, Fan; Li, Guang qiang

    2016-01-01

    Bi2Te3 based cutting waste powders from cutting wafers were firstly selected as raw materials to prepare p-type Bi2Te3 based thermoelectric (TE) materials. Through washing, reducing, composition correction, smelting and resistance pressing sintering (RPS) process, p-type (Bi,Sb)2Te3 alloy bulks with different nominal stoichiometries were successfully obtained. The evolution of microstructure and TE performance for (Bi,Sb)2Te3 alloys were investigated in detail. All evidences confirmed that most of contaminants from line cutting process such as cutting fluid and oxides of Bi, Sb or Te could be removed by washing, reducing and smelting process used in this work. The carrier content and corresponding TE properties could be adjusted effectively by appropriate composition correction treatment. At lastly, a bulk with a nominal stoichiometry of Bi0.44Sb1.56Te3 was obtained and its' dimensionless figure of merit (ZT) was about 1.16 at 90 °C. The ZT values of Bi0.36Sb1.64Te3 and Bi0.4Sb1.6Te3 alloy bulks could also reach 0.98 and 1.08, respectively. Different from the conventional recycling technology such as hydrometallurgy extraction methods, the separation and extraction of beneficial elements such as Bi, Sb and Te did not need to be performed and the Bi2Te3 based bulks with high TE properties could be directly obtained from the cutting waste powders. In addition, the recycling technology introduced here was green and more suitable for practical industrial application. It can improve material utilization and lower raw material costs of manufacturers.

  4. Magneto-optical Kerr effect in Cr-doped (Bi,Sb)2Te3 Thin Films

    NASA Astrophysics Data System (ADS)

    Pan, Yu; Yao, Bing; Richardella, Anthony; Kandala, Abhinav; Fraleigh, Robert; Lee, Joon Sue; Samarth, Nitin; Yeats, Andrew; Awschalom, David D.

    2014-03-01

    When a three-dimensional (3D) topological insulator (TI) is interfaced with magnetism, the breaking of time reversal symmetry results in new phenomena such as the recently observed quantum anomalous Hall effect [C.-Z. Zhang et al., Science340, 167 (2013)]. Thus motivated, we use the polar-mode magneto-optical Kerr effect (MOKE) to probe the temperature- and field-dependent magnetization in molecular beam epitaxy grown Cr-doped thin films of the 3D TI (Bi,Sb)2Te3. Square MOKE hysteresis loops observed at low temperatures indicate robust ferromagnetism with a perpendicular magnetic anisotropy and Curie temperature that varies from ~ 5 K to ~ 150 K, depending on sample details. A key question is the nature of the ferromagnetism: is it a carrier-mediated mechanism, Van Vleck mechanism or due to extrinsic clusters? We address this issue by varying the magnetic ion concentration and carrier density via sample composition as well as by varying the chemical potential by back gating. Finally, we use spatially-resolved MOKE to image the magnetization in these samples. Supported by ONR and DARPA.

  5. Transport studies on Cr-doped (Bi,Sb)2Te3 thin films with nearly quantized anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Liu, Minhao; Richardella, Anthony; Kandala, Abhinav; Wang, Wudi; Yazdani, Ali; Samarth, Nitin; Ong, N. Phuan

    2015-03-01

    We describe measurements of the quantum anomalous Hall effect in ferromagnetic Cr-doped (Bi,Sb)2Te3 thin films (6-8 QL thickness) grown on (111) SrTiO3 (STO) substrates by molecular beam epitaxy. The Fermi level is tuned close to the neutral point by tuning the growth flux ratios of Cr, Bi and Sb. Transport measurements were carried out in a dilution fridge at a base temperature of 20 mK. By tuning the chemical potential with a back gate on the STO substrate, we observed an anomalous Hall effect as high as 0.95h/e2, with a coercive field ~ 0.15 T and a narrow transition between positive/negative Hall plateaus. Transport measurements in a non-local configuration showed a Hall-effect-like non-local resistance with a systematic dependence on the back gate voltage and with pronounced peaks which resembled the non-local resistance of the quantum Hall effect. The non-local signal has a maximum that coincides with the maximum in Hall conductivity, indicating the edge channel as its origin. Our results show that the edge channel manifests itself in various transport properties even though the Hall resistance is not perfectly quantized. Supported by DARPA SPAWAR Grant No. N66001-11-1-4110 and MURI grant on Topological Insulators (ARO W911NF-12-1-0461).

  6. Synthesis, crystal structure and optical properties of BiMgVO 5

    NASA Astrophysics Data System (ADS)

    Benmokhtar, S.; El Jazouli, A.; Chaminade, J. P.; Gravereau, P.; Guillen, F.; de Waal, D.

    2004-11-01

    The new vanadate BiMgVO 5 has been prepared and its structure has been determined by single crystal X-ray diffraction: space group P21/n, a=7.542(6) Å, b=11.615(5) Å, c=5.305(3) Å, β=107.38(5)°, wR2=0.0447, R=0.0255. The structure consists of [Mg 2O 10] and [Bi 2O 10] dimers sharing their corners with [VO 4] tetrahedra. The ranges of bond lengths are 2.129-2.814 Å for Bi-O; 2.035-2.167 Å for Mg-O and 1.684-1.745 Å for V-O. V-O bond lengths determined from Raman band wavenumbers are between 1.679 and 1.747 Å. An emission band overlapping the entire visible region with a maximum around 650 nm is observed.

  7. Variable Temperature X-Ray Diffraction Study of Bismuth Magnesium Vanadate, BiMg 2VO 6

    NASA Astrophysics Data System (ADS)

    Radosavljevic, I.; Sleight, A. W.

    2000-01-01

    The space group for the structure of BiMg2VO6 at room temperature is shown to be Pmcn, rather than Amma as previously reported. However, when BiMg2VO6, is heated, its structure adopts the Amma space group at about 320 K. When the temperature is decreased through this transition, the (VO4)3- tetrahedron tilts, destroying one of the mirror planes in space group Amma. In space group Amma the (BiO2)1- chains have four equal Bi-O distances of 2.204 Å at 350 K. However, in the lower space group, there are two sets of Bi-O distances, 2.188 and 2.223 Å at 100 K. Unit cell edges in BiMg2VO6 increase with increasing temperature, giving an average linear thermal expansion of 5.2×10-6K-1 over the 100-350 K range.

  8. Synthesis, crystal structure and optical properties of BiMgVO{sub 5}

    SciTech Connect

    Benmokhtar, S.; El Jazouli, A. . E-mail: a.eljazouli@univh2m.ac.ma; Chaminade, J.P.; Gravereau, P.; Guillen, F.; Waal, D. de

    2004-11-01

    The new vanadate BiMgVO{sub 5} has been prepared and its structure has been determined by single crystal X-ray diffraction: space group P21/n, a=7.542(6)A, b=11.615(5)A, c=5.305(3)A, {beta}=107.38(5){sup o}, wR2=0.0447, R=0.0255. The structure consists of [Mg{sub 2}O{sub 10}] and [Bi{sub 2}O{sub 10}] dimers sharing their corners with [VO{sub 4}] tetrahedra. The ranges of bond lengths are 2.129-2.814A for Bi-O; 2.035-2.167A for Mg-O and 1.684-1.745A for V-O. V-O bond lengths determined from Raman band wavenumbers are between 1.679 and 1.747A. An emission band overlapping the entire visible region with a maximum around 650nm is observed.

  9. A New Bismuth Magnesium Vanadate with Reduced Vanadium: BiMg 2.5V 18.5O 38

    NASA Astrophysics Data System (ADS)

    Uma, S.; Sleight, A. W.

    2002-02-01

    A new oxide containing Bi, Mg, and V has been prepared, and its structure was determined from single-crystal X-ray diffraction data. The space group is Roverline3 with hexagonal cell dimensions of a=10.1985(9) and c=20.4875(14) Å. The formula may be written as BiMg2(MgV)V18O38 to indicate that one crystallographic site is occupied by a 1:1 mixture of Mg and V. The vanadium on that site appears to be in an oxidation state of 2. Thus, the average oxidation state of vanadium on the other three vanadium sites would be 3.72+. The site occupied exclusively by magnesium is in tetrahedral coordination to oxygen. All sites occupied by vanadium are octahedrally coordinated by oxygen. The low electrical resistivity of this compound suggests itinerant electron behavior.

  10. [Determination of Sb and Bi in 24 international geological reference materials by using pressurized acid digestion-ICP-MS].

    PubMed

    Hu, Zhao-chu; Gao, Shan; Liu, Xiao-ming; Yuan, Hong-lin; Liu, Ye; Diwu, Chun-rong

    2007-12-01

    The authors studied in detail the memory effect of Bi, Sb, As and Te in ICP-MS. The produced memory effects of these element were in the order of Bi>Sb>Te>As. Bi was seriously adsorbed by the polypropylene sample storing bottle and the sample introduction system in the low nitric acid medium (0.01%-1% HNO3). The washout effect of 0.1% HF was found to be better than those of 6% HNO3 and 0.1% HClO4. Under the given experiment conditions, the instrumental limit of detection was 0.001 and 0.0001 ng x mL(-1) for Sb and Bi, respectively. The authors report the determination of Sb and Bi in 24 international geological reference materials by using pressurized acid digestion-ICP-MS (including AGV-2, BHVO-2, BCR-2, etc.). Most of the results were found to be in reasonable agreement with the reported values in the literature. The authors' determined values of Sb for GSR-1 (granite; 0.30 microg x g(-1)) and JP-1 (peridotite; 0.045 microg x g(-1)) are obviously higher than those reported values. This is attributed to the efficient pressurized acid digestion, which is generally much more efficient than conventional wet digestions for insoluble minerals. PMID:18330312

  11. Synthesis, crystal structure, and optical properties of a new bismuth magnesium vanadate: BiMg 2VO 6

    NASA Astrophysics Data System (ADS)

    Huang, Jinfan; Sleight, Arthur W.

    1992-09-01

    A new bismuth magnesium vanadate, BiMg 2VO 6, has been synthesized and structurally characterized from single crystal X-ray diffraction data. It crystallizes in orthorhombic symmetry with a = 7.9136(6) Å, b = 12.246(2) Å, c = 5.444(2) Å, V = 527.6(2)Å 3, z = 4, and a space group of Cmcm (No. 63). An unusual fivefold coordination is found for Mg. The five O atoms bound to Mg form a square pyramidal coordination polyhedron with MgO bond lengths ranging from 1.973(7) to 2.066(3) Å. The Bi atom is coordinated by four O atoms with BiO bond lengths 2.213(2) Å forming a square pyramid. The V atom bonds to four O atoms with VO distances from 1.672(6) to 1.725(5) Å; all the OVO angles are very close to the value of an ideal VO 4 tetrahedron. The BiMg 2VO 6 structure may be viewed as connected chains of edge-shared BiO 4 units and corner-shared MgO 5 units extending along the c axis. These chains are then connected to each other through the VO 4 tetrahedra and edge sharing of the MgO 5 units. The absorption edge (about 450 nm) determined from the photothermal deflection technique is consistent with results from the excitation-emission spectrum. An emission band around 650 nm was observed. The IR spectrum of this compound is also reported.

  12. Utilisation de procedes de microfabrication pour la realisation de modules thermoelectriques a base d'alliages (Bi,Sb)2(Te,Se)3

    NASA Astrophysics Data System (ADS)

    Kashi, Siamak

    The production of thermoelectric devices uses nearly handmade techniques as an industry standard. These techniques are not suitable for the fabrication of smaller devices, where thermoelements are shorter than 1 millimetre. Researchers are focusing on how to decrease the height of thermoelements in a device, to the extent of depositing thermoelectric thin films. However, the best thermoelectric performances are obtained on modules fabricated from bulk material. Many tests were made to decrease the overall size of these devices, but until now, they would not permit to obtain the same range of performances as industrial devices. The aim of this project is to use microfabrication processes to obtain high power density thermoelectric devices. The precision obtained with the use of microfabrication techniques and automated methods has the potential to increase the performance and the industrial production of these devices. Fabrication steps were designed and tested in the facilities of the Ecole Polytechnique de Montreal to create hot extruded p-type and n-type (Bi,Sb)2(Te,Se)3 alloy based thermoelectric devices. These steps can be listed in three different categories, surface treatments, microfabrication methods and hot assembly. After cutting, p-type and n-type wafers were polished, underwent electropolishing and chemical etching before a diffusion barrier layer of nickel was deposited. Photolithography printed a pattern on the samples, where tin was then electroplated. A first assembly allowed soldering samples of each conduction type to alumina plates, before cutting the sample to free the thermoelements. A final assembly then created the finished devices by soldering of the two parts containing p-type and n-type thermoelements. The produced devices were functional, validating the designed steps. Electrical characterization of the best modules obtained indicate that the electromotive force is comparable to that of commercial modules under the same conditions

  13. Synthesis and characterization of (1-x)Bi(Mg2/3Sb1/3)O3-xPbTiO3 piezoceramics

    NASA Astrophysics Data System (ADS)

    Upadhyay, Ashutosh; Dwivedi, Saurabh; Pandey, Rishikesh; Singh, Akhilesh Kumar

    2016-05-01

    We present here the comprehensive x-ray diffraction and polarization-electric field hysteresis studies on (1-x)Bi(Mg2/3Sb1/3)O3-xPbTiO3 piezoceramics with x = 0.52, 0.56 and 0.60. The powder x-ray diffraction data reveals the presence of tetragonal phase for all the compositions. The saturation of hysteresis loop is observed for x ≤ 0.56.

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

    SciTech Connect

    Guo, Rui; Zhang, Gaoke; Liu, Jiu

    2013-05-15

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

  15. Comparison of crystal growth and thermoelectric properties of n-type Bi-Se-Te and p-type Bi-Sb-Te nanocrystalline thin films: Effects of homogeneous irradiation with an electron beam

    SciTech Connect

    Takashiri, Masayuki Imai, Kazuo; Uyama, Masato; Nishi, Yoshitake; Hagino, Harutoshi; Miyazaki, Koji; Tanaka, Saburo

    2014-06-07

    The effects of homogenous electron beam (EB) irradiation on the crystal growth and thermoelectric properties of n-type Bi-Se-Te and p-type Bi-Sb-Te thin films were investigated. Both types of thin films were prepared by flash evaporation, after which homogeneous EB irradiation was performed at an acceleration voltage of 0.17 MeV. For the n-type thin films, nanodots with a diameter of less than 10 nm were observed on the surface of rice-like nanostructures, and crystallization and crystal orientation were improved by EB irradiation. The resulting enhancement of mobility led to increased electrical conductivity and thermoelectric power factor for the n-type thin films. In contrast, the crystallization and crystal orientation of the p-type thin films were not influenced by EB irradiation. The carrier concentration increased and mobility decreased with increased EB irradiation dose, possibly because of the generation of defects. As a result, the thermoelectric power factor of p-type thin films was not improved by EB irradiation. The different crystallization behavior of the n-type and p-type thin films is attributed to atomic rearrangement during EB irradiation. Selenium in the n-type thin films is more likely to undergo atomic rearrangement than the other atoms present, so only the crystallinity of the n-type Bi-Se-Te thin films was enhanced.

  16. Electric field induced lattice strain in pseudocubic Bi(Mg1/2Ti1/2)O3-modified BaTiO3-BiFeO3 piezoelectric ceramics

    NASA Astrophysics Data System (ADS)

    Fujii, Ichiro; Iizuka, Ryo; Nakahira, Yuki; Sunada, Yuya; Ueno, Shintaro; Nakashima, Kouichi; Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Wada, Satoshi

    2016-04-01

    Contributions to the piezoelectric response in pseudocubic 0.3BaTiO3-0.1Bi(Mg1/2Ti1/2)O3-0.6BiFeO3 ceramics were investigated by synchrotron X-ray diffraction under electric fields. All of the lattice strain determined from the 110, 111, and 200 pseudocubic diffraction peaks showed similar lattice strain hysteresis that was comparable to the bulk butterfly-like strain curve. It was suggested that the hysteresis of the lattice strain and the lack of anisotropy were related to the complex domain structure and the phase boundary composition.

  17. Synthesis and structural studies on (1−x)Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}−xPbTiO{sub 3} piezoceramics

    SciTech Connect

    Upadhyay, Ashutosh Pandey, Rishikesh Anand, Shashwat Singh, Akhilesh K.

    2014-04-24

    We present here the structural studies on (1−x)Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}−xPbTiO{sub 3} (BMT-xPT) piezoceramics with x=0.28, 0.37 and 0.45 using powder x-ray diffraction data. Rietveld refinement of powder x-ray diffraction data reveals the tetragonal structure (space group P4mm) for the compositions with x>0.40 and rhombohedral (space group R3m) for the compositions with x<0.30 of BMT-xPT ceramics. The morphotropic phase boundary is found for the intermediate composition with 0.30

  18. Phase transition and chemical order in the ferroelectric perovskite (1-x)Bi(Mg3/4W1/4)O3-xPbTiO3 solid solution system

    NASA Astrophysics Data System (ADS)

    Stringer, C. J.; Eitel, R. E.; Shrout, T. R.; Randall, C. A.; Reaney, I. M.

    2005-01-01

    Building on the ferroelectric family based on the Bi(Me+3)O3-PbTiO3 solid solutions, the complex solid solution (1-x )Bi(Mg3/4W1/4)O3-xPbTiO3 [(1-x)BMW-xPT] was investigated. This system was found to exhibit a broad morphotropic phase boundary at x ˜0.48mol% PbTiO3 with a corresponding Curie temperature of 205°C separating pseudocubic and tetragonal ferroelectric phases. Based on dielectric, x-ray diffraction (XRD), and calorimetric data, a simple dielectric phase field diagram was established. On further structural analysis with diffraction contrast transmission electron microscopy along with XRD, evidence of B-site chemical ordering was found for the (1-x )Bi(Me'Me″)O3-xPbTiO3 perovskite family.

  19. Structural and dielectric properties of BaTiO3-Bi(Mg1/2Ti1/2)O3 thin films fabricated by chemical solution deposition

    NASA Astrophysics Data System (ADS)

    Moki, Shota; Kimura, Junichi; Kaneko, Noriyuki; Funakubo, Hiroshi; Uchida, Hiroshi

    2014-09-01

    Thin films of the BaTiO3-Bi(Mg1/2Ti1/2)O3 (BT-BMT) solid-solution system were fabricated with the aim of achieving a stable temperature coefficient of capacitance (TCC) favorable for high-temperature electronics. A single perovskite phase with pseudocubic symmetry was obtained for the films fabricated by chemical solution deposition on (111)Pt/TiO2/(100)Si substrates in the composition range of x = 0-0.80 for (1 - x)BT-xBMT. BMT added to the BaTiO3-based films enhanced the crystallinity of the perovskite phase and resulted in saturated P-E hysteresis behavior with remanent polarization of up to 13 µC/cm2. BMT addition led to gradual dielectric relaxation, which also resulted in stable TCC behavior with a relative dielectric constant of approximately 400 in the temperature range of RT - 400 °C, especially for the BT-BMT films with x = 0.20-0.40.

  20. Simultaneous achievement of high dielectric constant and low temperature dependence of capacitance in (111)-oriented BaTiO3-Bi(Mg0.5Ti0.5)O3-BiFeO3 solid solution thin films

    NASA Astrophysics Data System (ADS)

    Kimura, Junichi; Chentir, Mohamed-Tahar; Shimizu, Takao; Uchida, Hiroshi; Funakubo, Hiroshi

    2016-01-01

    The temperature dependence of the capacitance of (111)c-oriented (0.90-x)BaTiO3-0.10Bi(Mg0.5Ti0.5)O3-xBiFeO3 solid solution films is investigated. These films are prepared on (111)cSrRuO3/(111)Pt/TiO2/SiO2/(100)Si substrates by the chemical solution deposition technique. All the films have perovskite structures and the crystal symmetry at room temperature varies with increasing x ratio, from pseudocubic when x = 0-0.30 to rhombohedral when x = 0.50-0.90. The pseudocubic phase shows a high relative dielectric constant (ɛr) (ranging between 400 and 560 at room temperature and an operating frequency of 100 kHz) and a low temperature dependence of capacitance up to 400°C, while maintaining a dielectric loss (tan δ) value of less than 0.2 at 100 kHz. In contrast, ɛr for the rhombohedral phase increases monotonically with increasing temperature up to 250°C, and increasingly high tan δ values are recorded at higher temperatures. These results indicate that pseudocubic (0.90-x)BaTiO3-0.10Bi(Mg0.5Ti0.5)O3-xBiFeO3 solid solution films with (111) orientation are suitable candidates for high-temperature capacitor applications.

  1. Lead- and alkali-metal-free BaTiO3-Bi(Mg0.5Ti0.5)O3-BiFeO3 solid-solution thin films with high dielectric constant prepared on Si substrates by solution-based method

    NASA Astrophysics Data System (ADS)

    Kimura, Junichi; Mohamed-Tahar, Chentir; Shimizu, Takao; Uchida, Hiroshi; Funakubo, Hiroshi

    2014-09-01

    Lead- and alkali-metal-free BaTiO3-Bi(Mg0.5Ti0.5)O3-BiFeO3 solid-solution thin films were prepared on (111)cSrRuO3/(111)Pt/TiO2/SiO2/(100)Si substrates by chemical solution deposition (CSD) and their crystal structure and dielectric properties were investigated. The lattice spacing as a function of z/(x + z) in xBaTiO3-0.1Bi(Mg0.5Ti0.5)O3-zBiFeO3 indicated the existence of phase boundaries (pseudocubic/rhombohedral) in the range of z/(x + z) = 0.33-0.56, where the relatively high relative dielectric constant, ɛr, of above 800 was obtained. On the other hand, dielectric loss, tan δ, of below 0.2 was confirmed in the range z/(x + z) = 0-0.87, which rapidly increased toward z/(x + z) = 1.0. The relatively high ɛr values of these films deposited on Si substrates by a solution-based process suggest that they can be used as alternative to Pb(Zr,Ti)O3, KNbO3, and (Bi1/2Na1/2)TiO3-based films.

  2. The motley family of polar compounds (MV)[M(X{sub 5-x}X Prime {sub x})] based on anionic chains of trans-connected M{sup (III)}(X,X Prime ){sub 6} octahedra (M=Bi, Sb; X, X Prime =Cl, Br, I) and methylviologen (MV) dications

    SciTech Connect

    Leblanc, Nicolas; Mercier, Nicolas; Allain, Magali; Toma, Oksana; Auban-Senzier, Pascale; Pasquier, Claude

    2012-11-15

    The search for hybrid organic-inorganic materials remains a great challenge in the field of ferroelectrics. Following the discovery of the room temperature ferroelectric material (MV)[BiI{sub 3}Cl{sub 2}] (MV{sup 2+}: methylviologen) exhibiting the highest polarization value in the field of hybrid ferroelectrics, we report here nine new hybrids with the general formulation (MV)[M{sup (III)}X{sub 5-x}X Prime {sub x}] (M=Bi, Sb; X, X Prime =Cl, Br, I): (MV)[BiCl{sub 3.3}Br{sub 1.7}] (1), (MV)[BiCl{sub 1.3}Br{sub 3.7}] (2), (MV)[BiBr{sub 3.2}I{sub 1.8}] (3), (MV)[SbCl{sub 5}] (4), (MV)[SbBr{sub 5}] (5), (MV)[SbCl{sub 3.8}Br{sub 1.2}] (6), (MV)[SbCl{sub 2.4}Br{sub 2.6}] (7), (MV)[SbI{sub 3}Cl{sub 2}] (8) and (MV)[SbBr{sub 3.8}I{sub 1.2}] (9). Depending on the presence of polar chains or not, and on the coupling of polar chains, two types of centrosymmetrical structures [C1] and [C2] and two types of polar structures [P1] and [P2] are defined. (2) undergoes a paraelectric-to-relaxor ferroelectric transition around 100-150 K depending of the frequency showing that the Curie temperature, T{sub C}, of (MV)[BiBr{sub 5}] (243 K) can be modulated by the substitution of Br by Cl. The most interesting family is the [P2] type because the syn coupling of polar chains is in favor of high polarization values, as in (MV)[BiI{sub 3}Cl{sub 2}]. Five of the nine new hybrids, (4), (6-9), which have the [P2] type structure are potential ferroelectrics. - Graphical abstract: The methylviologen haloantimonate (MV)[SbX{sub 5-x}X Prime {sub x}] families (X, X Prime =Cl, Br, I) - [P1] and [P2] are the two kinds of polar structures - and view of the (MV)[SbBr{sub 3.8}I{sub 1.2}] hybrid based on chiral polar chains which are in syn coupling. Highlights: Black-Right-Pointing-Pointer Nine hybrids based on methylviologen and halometalate chains have been discovered. Black-Right-Pointing-Pointer The polar nature of chains is due to the ns{sup 2} stereoactivity of Sb{sup (III)} or Bi{sup (III

  3. Bismuth-induced dielectric relaxation in the (1-x)La(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-xBi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3} perovskite system

    SciTech Connect

    Salak, Andrei N.; Pullar, Robert C.; Alford, Neil McN.

    2008-07-01

    The temperature variation of the dielectric permittivity and loss of the solid solutions (1-x)La(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-xBi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3} [(1-x)LMT-xBMT] (0{<=}x{<=}0.3) measured at radio, microwave, and far infrared frequency ranges has been analyzed in comparison with that observed in other bismuth-containing and bismuth-free perovskite ceramics based on LMT. It has been found that the low temperature dielectric response of the (1-x)LMT-xBMT compositions with x{>=}0 is frequency dependent over a wide range from radio to microwave frequencies. The considerable compositional growth of the dielectric permittivity and loss associated with the amount of bismuth in the system was revealed to be not contributed by the lattice polar phonon modes. The effect was suggested to be related to the low-temperature dielectric relaxation process due to a hopping movement of charge carriers in crystallographic A-sites of the perovskite lattice. Particular role of local lattice distortions caused by the anisotropic chemical bonds involving bismuth 6s{sup 2} electrons in a localization of hopping charge carriers in perovskites and other oxygen-octahedral compositions is considered. The characteristic features of the Bi-induced dielectric relaxation and those typical of the ferroelectric relaxors are compared and discussed.

  4. Role of point defects in bipolar fatigue behavior of Bi(Mg1/2Ti1/2)O3 modified (Bi1/2K1/2)TiO3-(Bi1/2Na1/2)TiO3 relaxor ceramics

    NASA Astrophysics Data System (ADS)

    Kumar, Nitish; Ansell, Troy Y.; Cann, David P.

    2014-04-01

    Lead-free Bi(Mg1/2Ti1/2)O3-(Bi1/2K1/2)TiO3-(Bi1/2Na1/2)TiO3 (BMT-BKT-BNT) ceramics have been shown to exhibit large electromechanical strains under high electric fields along with negligible fatigue under strong electric fields. To investigate the role of point defects on the fatigue characteristics, the composition 5BMT-40BKT-55BNT was doped to incorporate acceptor and donor defects on the A and B sites by adjusting the Bi/Na and Ti/Mg stoichiometries. All samples had pseudo-cubic symmetries based on x-ray diffraction, typical of relaxors. Dielectric measurements showed that the high and low temperature phase transitions were largely unaffected by doping. Acceptor doping resulted in the observation of a typical ferroelectric-like polarization with a remnant polarization and strain hysteresis loops with significant negative strain. Donor-doped compositions exhibited characteristics that were indicative of an ergodic relaxor phase. Fatigue measurements were carried out on all of the compositions. While the A-site acceptor-doped composition showed a small degradation in maximum strain after 106 cycles, the other compositions were essentially fatigue free. Impedance measurements were used to identify the important conduction mechanisms in these compositions. As expected, the presence of defects did not strongly influence the fatigue behavior in donor-doped compositions owing to the nature of their reversible field-induced phase transformation. Even for the acceptor-doped compositions, which had stable domains in the absence of an electric field at room temperature, there was negligible degradation in the maximum strain due to fatigue. This suggests that either the defects introduced through stoichiometric variations do not play a prominent role in fatigue in these systems or it is compensated by factors like decrease in coercive field, an increase in ergodicity, symmetry change, or other factors.

  5. Ultraschall-Geschwindigkeit und-Absorption in Bi-In-Schmelzen /Ultrasonic Velocity and Absorption in Bi-In-melts

    NASA Astrophysics Data System (ADS)

    Bek, R.; Steeb, S.

    1981-02-01

    Using the pulse-echo method the ultrasonic velocity and absorption was measured with Bi-In-melts in the temperature range from liquidus up to more than 600 °C. The frequencies used reached from 10 MHz up to 130 MHz. Within the experimental accuracy no frequency dependence of the absorption coefficient α/f2 could be detected. An excess absorption can be observed, which for the molten elements can be explained by fluctuations of the packing density. For the molten alloys additionally concentration fluctuations play an important role. Thus an understanding of the temperature dependency of the ultrasonic velocity and absorption can be achieved.

  6. Role of point defects in bipolar fatigue behavior of Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3} modified (Bi{sub 1/2}K{sub 1/2})TiO{sub 3}-(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3} relaxor ceramics

    SciTech Connect

    Kumar, Nitish Ansell, Troy Y.; Cann, David P.

    2014-04-21

    Lead-free Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-(Bi{sub 1/2}K{sub 1/2})TiO{sub 3}-(Bi{sub 1/2}Na{sub 1/2})TiO{sub 3} (BMT-BKT-BNT) ceramics have been shown to exhibit large electromechanical strains under high electric fields along with negligible fatigue under strong electric fields. To investigate the role of point defects on the fatigue characteristics, the composition 5BMT-40BKT-55BNT was doped to incorporate acceptor and donor defects on the A and B sites by adjusting the Bi/Na and Ti/Mg stoichiometries. All samples had pseudo-cubic symmetries based on x-ray diffraction, typical of relaxors. Dielectric measurements showed that the high and low temperature phase transitions were largely unaffected by doping. Acceptor doping resulted in the observation of a typical ferroelectric-like polarization with a remnant polarization and strain hysteresis loops with significant negative strain. Donor-doped compositions exhibited characteristics that were indicative of an ergodic relaxor phase. Fatigue measurements were carried out on all of the compositions. While the A-site acceptor-doped composition showed a small degradation in maximum strain after 10{sup 6} cycles, the other compositions were essentially fatigue free. Impedance measurements were used to identify the important conduction mechanisms in these compositions. As expected, the presence of defects did not strongly influence the fatigue behavior in donor-doped compositions owing to the nature of their reversible field-induced phase transformation. Even for the acceptor-doped compositions, which had stable domains in the absence of an electric field at room temperature, there was negligible degradation in the maximum strain due to fatigue. This suggests that either the defects introduced through stoichiometric variations do not play a prominent role in fatigue in these systems or it is compensated by factors like decrease in coercive field, an increase in ergodicity, symmetry change, or other factors.

  7. Measurement of Activity of Indium in Liquid Bi-In-Sn Alloys by EMF Method

    NASA Astrophysics Data System (ADS)

    Kumar, M. R.; Mohan, S.; Behera, C. K.

    2016-08-01

    The electrochemical technique based on a molten salt electrolyte galvanic cell has been used to measure the activity of indium in liquid Bi-In-Sn alloys in the temperature range of 723 K to 855 K along three ternary sections. The activity of tin in Bi-Sn binary alloys has also been measured by the same technique in the above temperature range. The activity of indium in Bi-In-Sn alloys shows negative deviation from Raoult's law for most of the compositions and slight positive deviations for a few indium-rich compositions. The ternary excess molar free energies have been calculated by Darken's treatment. Isoactivity curves at 813 K in the ternary Bi-In-Sn alloys were derived by combining the activity data of In-Sn and Bi-In alloys. The values of excess molar free energy obtained in this study are compared with those calculated from the Muggianu model at 813 K.

  8. Measurement of Activity of Indium in Liquid Bi-In-Sn Alloys by EMF Method

    NASA Astrophysics Data System (ADS)

    Kumar, M. R.; Mohan, S.; Behera, C. K.

    2016-05-01

    The electrochemical technique based on a molten salt electrolyte galvanic cell has been used to measure the activity of indium in liquid Bi-In-Sn alloys in the temperature range of 723 K to 855 K along three ternary sections. The activity of tin in Bi-Sn binary alloys has also been measured by the same technique in the above temperature range. The activity of indium in Bi-In-Sn alloys shows negative deviation from Raoult's law for most of the compositions and slight positive deviations for a few indium-rich compositions. The ternary excess molar free energies have been calculated by Darken's treatment. Isoactivity curves at 813 K in the ternary Bi-In-Sn alloys were derived by combining the activity data of In-Sn and Bi-In alloys. The values of excess molar free energy obtained in this study are compared with those calculated from the Muggianu model at 813 K.

  9. Quantum-limit anisotropic magnetoresistance of semiconducting n-BiSb alloys

    NASA Astrophysics Data System (ADS)

    Redko, N. A.; Kagan, V. D.; Volkov, M. P.

    2009-12-01

    The magnetic-field dependences of resistivity and Hall coefficient of single crystals Bi 0.93Sb 0.07 alloys were investigated at low temperatures. For H∥ C3 and j∥ C1 orientation the cyclotron frequencies of all three ellipsoids are equal and the electron concentration raises with the magnetic field in quantum limit. For H∥ C2 and j∥ C1 the quantum oscillations of resistivity were observed connected with the electrons of two ellipsoids, at higher fields the transition to the quantum limit takes place. The magnetic field increase in the quantum limit leads to the increase of electron energy from secondary ellipsoids and to their migration to the main ellipsoid. For H∥ C1∥ j orientation the quantum oscillations of resistivity were connected with all three ellipsoids. The electron energy for main ellipsoid rises in quantum limit with magnetic field, leading to the migration of carriers from main ellipsoid to the secondary ellipsoids.

  10. Use of extruded alloys Bi-Sb in low temperature thermoelements

    NASA Astrophysics Data System (ADS)

    Banaga, M. P.; Buimistr, B. S.; Moloshnik, E. F.

    1988-10-01

    Values of thermoelectric factor of quality for extruded alloys Bi_88Sb_12 of n-type in the temperatures interval 200-100K and a magnetic field induction 0-0.3Tl has been given. Temperature dependencies of optimal ratios of crossections of frames of thermoelements, containing extruded n-frame for various values of the induction of the transversal magnetic field has been analysed. Temperature dependencies of the quality factors of the thermoelements has been given. Calculated and experimental temperature falls on thermoelements and their dependenices on the crossections frames ratios for various temperatures of the heat evacuation has been analysed. Thermoelements examined are designed for application in low-temperature coolers.

  11. Materials Data on Ba2BiSbO6 (SG:148) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

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

  12. Single-crystal growth and thermoelectric properties of Ge(Bi,Sb)4Te7.

    PubMed

    von Rohr, Fabian; Schilling, Andreas; Cava, Robert J

    2013-02-20

    The thermoelectric properties between 10 and 300 K and the growth of single crystals of n-type and p-type GeBi(4)Te(7), GeSb(4)Te(7) and Ge(Bi(1-x)Sb(x))(4)Te(7) solid solution are reported. Single crystals were grown by the modified Bridgman method, and p-type behavior was achieved by the substitution of Bi by Sb in GeBi(4)Te(7). The thermopower in the Ge(Bi(1-x)Sb(x))(4)Te(7) solid solution ranges from -117 to +160 μV K(-1). The crossover from n-type to p-type is continuous with increasing Sb content and is observed at x ≈0.15. The highest thermoelectric efficiencies among the tested n-type and p-type samples are Z(n)T = 0.11 and Z(p)T = 0.20, respectively. For an optimal n-p couple in this alloy system the composite figure of merit is Z(np)T = 0.17 at room temperature. PMID:23343638

  13. Integrated measurements of 212Pb and 212Bi in the air by rotating filters.

    PubMed

    Pressyanov, D S

    1995-02-01

    A method for determining time integrated concentrations of 212Pb and 212Bi in the air is proposed. It employs solid state nuclear track detectors covered with an absorber and placed around a rotating filter. Results from experiments carried out in an artificial 220Rn atmosphere have been presented. They reveal that the method works within the range of integrated concentrations for indoor measurements. The experimental error was about 7% for 212Pb and 23% for 212Bi. Possibilities for improving the accuracy have been discussed. PMID:7814259

  14. Characterization of Low-Melting-Point Sn-Bi-In Lead-Free Solders

    NASA Astrophysics Data System (ADS)

    Li, Qin; Ma, Ninshu; Lei, YongPing; Lin, Jian; Fu, HanGuang; Gu, Jian

    2016-02-01

    Development of lead-free solders with low melting temperature is important for substitution of Pb-based solders to reduce direct risks to human health and the environment. In the present work, Sn-Bi-In solders were studied for different ratios of Bi and Sn to obtain solders with low melting temperature. The microstructure, thermal properties, wettability, mechanical properties, and reliability of joints with Cu have been investigated. The results show that the microstructures of the Sn-Bi-In solders were composed of β-Sn, Bi, and InBi phases. The intermetallic compound (IMC) layer was mainly composed of Cu6Sn5, and its thickness increased slightly as the Bi content was increased. The melting temperature of the solders was around 100°C to 104°C. However, when the Sn content exceeded 50 wt.%, the melting range became larger and the wettability became worse. The tensile strength of the solder alloys and solder joints declined with increasing Bi content. Two fracture modes (IMC layer fracture and solder/IMC mixed fracture) were found in solder joints. The fracture mechanism of solder joints was brittle fracture. In addition, cleavage steps on the fracture surface and coarse grains in the fracture structure were comparatively apparent for higher Bi content, resulting in decreased elongation for both solder alloys and solder joints.

  15. Surface Tomonaga-Luttinger-Liquid State on Bi/InSb(001).

    PubMed

    Ohtsubo, Yoshiyuki; Kishi, Jun-Ichiro; Hagiwara, Kenta; Le Fèvre, Patrick; Bertran, François; Taleb-Ibrahimi, Amina; Yamane, Hiroyuki; Ideta, Shin-Ichiro; Matsunami, Masaharu; Tanaka, Kiyohisa; Kimura, Shin-Ichi

    2015-12-18

    A 1D metallic surface state was created on an anisotropic InSb(001) surface covered with Bi. Angle-resolved photoelectron spectroscopy (ARPES) showed a 1D Fermi contour with almost no 2D distortion. Close to the Fermi level (E_{F}), the angle-integrated photoelectron spectra showed power-law scaling with the binding energy and temperature. The ARPES plot above E_{F}, obtained thanks to a thermally broadened Fermi edge at room temperature, showed a 1D state with continuous metallic dispersion across E_{F} and power-law intensity suppression around E_{F}. These results strongly suggest a Tomonaga-Luttinger liquid on the Bi/InSb(001) surface. PMID:26722934

  16. A comparative study of the microstructures observed in statically cast and continuously cast Bi-In-Sn ternary eutectic alloy

    SciTech Connect

    Sengupta, S.; Soda, H.; McLean, A.; Rutter, J.W.

    2000-01-01

    A ternary eutectic alloy with a composition of 57.2 pct Bi, 24.8 pct In, and 18 pct Sn was continuously cast into wire of 2 mm diameter with casting speeds of 14 and 79 mm/min using the Ohno Continuous Casting (OCC) process. The microstructures obtained were compared with those of statically cast specimens. Extensive segregation of massive Bi blocks, Bi complex structures, and tin-rich dendrites was found in specimens that were statically cast. Decomposition of {radical}Sn by a eutectoid reaction was confirmed based on microstructural evidence. Ternary eutectic alloy with a cooling rate of approximately 1 C/min formed a double binary eutectic. The double binary eutectic consisted of regions of BiIn and decomposed {radical}Sn in the form of a dendrite cell structure and regions of Bi and decomposed {radical}Sn in the form of a complex-regular cell. The Bi complex-regular cells, which are a ternary eutectic constituent, existed either along the boundaries of the BiIn-decomposed {radical}Sn dendrite cells or at the front of elongated dendrite cell structures. In the continuously cast wires, primary Sn dendrites coupled with a small Bi phase were uniformly distributed within the Bi-In alloy matrix. Neither massive Bi phase, Bi complex-regular cells, no BiIn eutectic dendrite cells were observed, resulting in a more uniform microstructure in contrast to the heavily segregated structures of the statically cast specimens.

  17. Growth and properties of chemical solution deposited BiInO3-PbTiO3 films

    NASA Astrophysics Data System (ADS)

    Ko, S. W.; Yeo, H. G.; Trolier-McKinstry, S.

    2009-10-01

    The dielectric, ferroelectric, and piezoelectric properties of chemical solution deposited xBiInO3-(1-x)PbTiO3 (0.10≤x ≤0.35) thin films on platinized silicon substrates were investigated. Using a PbTiO3 seed layer, phase pure xBiInO3-(1-x)PbTiO3 (0.10≤x ≤0.35) thin films were prepared. For a 470 nm thick 0.15BiInO3-0.85PbTiO3 film, the room temperature permittivity was 650, while the dielectric loss tangent was below 2%. The coercive field and remanent polarization were 73 kV/cm and 22 μC/cm2, respectively. The ferroelectric transition temperatures of the xBiInO3-(1-x)PbTiO3 (x =0.10-0.20) films were all in excess of 550 °C. For x=0.15, the e31,f piezoelectric coefficient was -2.7 C/m2.

  18. Heavily Cr-doped (Bi,Sb)2Te3 as a ferromagnetic insulator with electrically tunable conductivity

    NASA Astrophysics Data System (ADS)

    Ou, Yunbo; Liu, Chang; Zhang, Liguo; Feng, Yang; Jiang, Gaoyuan; Zhao, Dongyang; Zang, Yunyi; Zhang, Qinghua; Gu, Lin; Wang, Yayu; He, Ke; Ma, Xucun; Xue, Qi-Kun

    2016-08-01

    With molecular beam epitaxy we have grown Cry(BixSb1-x)2-yTe3 thin films with homogeneous distribution of Cr dopants and Curie temperature up to 77 K. The films with Cr concentration y ≥ 0.39 are found to be topologically trivial, highly insulating ferromagnets, whose conductivity can be tuned over two orders of magnitude by gate voltage. The ferromagnetic insulators with electrically tunable conductivity can be used to realize the quantum anomalous Hall effect at higher temperature in topological insulator heterostructures and to develop field effect devices for spintronic applications.

  19. Enhanced power factor and high-pressure effects in (Bi,Sb){sub 2}(Te,Se){sub 3} thermoelectrics

    SciTech Connect

    Ovsyannikov, Sergey V. E-mail: sergey2503@gmail.com; Morozova, Natalia V.; Korobeinikov, Igor V.; Vokhmyanin, Alexander P.; Shchennikov, Vladimir V.; Lukyanova, Lidia N.; Usov, Oleg A.; Kutasov, Vsevolod A.; Manakov, Andrey Y.; Likhacheva, Anna Y.; Ancharov, Alexey I.; Berger, Ivan F.; Kulbachinskii, Vladimir A.; Okada, Taku

    2015-04-06

    We investigated the effects of applied high pressure on thermoelectric, electric, structural, and optical properties of single-crystalline thermoelectrics, Bi{sub 2}Te{sub 3}, Bi{sub x}Sb{sub 2−x}Te{sub 3} (x = 0.4, 0.5, 0.6), and Bi{sub 2}Te{sub 2.73}Se{sub 0.27} with the high thermoelectric performance. We established that moderate pressure of about 2–4 GPa can greatly enhance the thermoelectric power factor of all of them. X-ray diffraction and Raman studies on Bi{sub 2}Te{sub 3} and Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} found anomalies at similar pressures, indicating a link between crystal structure deformation and physical properties. We speculate about possible mechanisms of the power factor enhancement and suppose that pressure/stress tuning can be an effective tool for the optimization of the thermoelectric performance.

  20. Mechanical properties of (Bi,Sb)2Te3 solid solutions obtained by directional crystallization and spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Lavrent'ev, M. G.; Osvenskii, V. B.; Pivovarov, G. I.; Sorokin, A. I.; Bulat, L. P.; Bublik, V. T.; Tabachkova, N. Yu.

    2016-01-01

    We have studied the temperature dependence of the mechanical strength at uniaxial compression for solid solutions based on bismuth and antimony chalcogenides, which were prepared by three methods: (i) vertical zone melting (VZM), (ii) hot extrusion, and (iii) spark plasma sintering (SPS). In the samples of solid solutions obtained by VZM and extrusion, a brittle-ductile transition was observed in a wised temperature interval of 200-350°C. In nanostructured SPS samples, transition from brittle to plastic fracture was observed within 170-200°C. The room-temperature strength of nanostructured samples was eight to nine times as large as that of VZM samples, and the stress-strain curves of these materials were significantly different. At a temperature of about 300°C, the strength of nanostructured solid solutions decreases to nearly zero.

  1. Mechanical robust BiSbTe alloys with superior thermoelectric performance: A case study of stable hierarchical nanostructured thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Su, Xianli; Zheng, Yun; Tang, Xinfeng; Uher, Ctirad; Tang's Group Team; Uher's Group Team

    2015-03-01

    Poor machinability and susceptibility to brittle fracture of commercial ingots often impose significant limitations on the manufacturing process and durability of thermoelectric devices. In this study, melt spinning combined with plasma activated sintering (MS-PAS) method is employed with commercial p-type zone-melted (ZM) ingots of Bi0.5Sb1.5Te3. This fast synthesis approach achieves hierarchical structures and in-situ nanoscale precipitates, resulting in the simultaneous improvement of thermoelectric performance and mechanical properties. Benefitting from a strong suppression of the lattice thermal conductivity, a peak ZT of 1.22 is achieved at 340 K in MS-PAS synthesized structures, representing about a 40% enhancement over that of ZM ingots. Moreover, MS-PAS specimens with hierarchical structures exhibit superior machinability and mechanical properties with an almost 30% enhancement in the fracture toughness, eightfold and a factor of six increase in the compressive and flexural strength respectively. We wish to acknowledge support from the National Basic Research Program of China (973 program) under Project 2013CB632502.

  2. Molecular Beam Epitaxy Growth of GaBi, InBi and InGaBi

    NASA Astrophysics Data System (ADS)

    Keen, B.; Makin, R.; Stampe, P. A.; Kennedy, R. J.; Piper, L. F. J.; McCombe, B.; McConville, C. F.; Durbin, S. M.

    2014-03-01

    Recent interest in bismuth alloys of III-V semiconductors for infrared and far-infrared device applications, specifically GaAsBi and InAsBi, has indicated that further study of the III-Bi family of binary compounds would be of great help in improving the quality of these material systems. While immiscibility issues have so far frustrated the growth of GaBi and AlBi, InBi is less problematic, and we have grown it by molecular beam epitaxy on (001) GaAs substrates. However, regions of varying composition exist across the substrate due to poor wetting of the surface. In an effort to improve film quality we have continued to refine the growth parameters by adjusting substrate temperature, beam flux ratio, and deposition rate. Characterization of these films has been performed by x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Additionally, we have explored growth of GaBi and In1-xGaxBi at low Ga mole fractions, and modeled this using molecular dynamics simulations. This work is supported by the Research Foundation of the State University of New York Collaborations Fund.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  4. Phase transitions in the liquid-vapor interface of dilute alloys of Bi in Ga: New experimental studies

    SciTech Connect

    Li, Dongxu; Jiang, Xu; Yang, Bin; Rice, Stuart A.

    2010-07-19

    We report the results of measurements of x-ray reflectivity and grazing incidence x-ray diffraction from the liquid-vapor interfaces of four dilute alloys of Bi in Ga with mole fractions x{sub Bi} = 0.0032, 0.0023, 0.00037, and 0.000037. The monolayer coverage of the alloys with x{sub Bi} = 0.0023, and x{sub Bi} = 0.00037 is about 0.85 and only very slightly temperature dependent. The monolayer coverage in the lowest-concentration alloy, with x{sub Bi} = 0.000037, ranged from 0.82 at 29 C to 0.58 at 110 C. In none of these alloys, down to the lowest temperature used, 29 C, can we find any evidence for crystallization of the Bi monolayer that segregates as the outermost stratum of the liquid-vapor interface. Drawing on theoretical arguments we propose that the transitions inferred from the second-harmonic generation and plasma generation studies of dilute Bi in Ga alloys are from the liquid state to the hexatic state of the Bi monolayer. The data for the alloy with x{sub Bi} = 0.000037 suggest that near 80 C there is a disordered phase-to-disordered phase transition.

  5. β -detected NMR of 8Li+ in Bi, Sb, and the topological insulator Bi0.9Sb0.1

    NASA Astrophysics Data System (ADS)

    MacFarlane, W. A.; Tschense, C. B. L.; Buck, T.; Chow, K. H.; Cortie, D. L.; Hariwal, A. N.; Kiefl, R. F.; Koumoulis, D.; Levy, C. D. P.; McKenzie, I.; McGee, F. H.; Morris, G. D.; Pearson, M. R.; Song, Q.; Wang, D.; Hor, Y. S.; Cava, R. J.

    2014-12-01

    We report the NMR Knight shift and spin-lattice relaxation of 8Li+ implanted ˜100 nm into single crystals of semimetallic Sb, Bi, and topologically insulating Bi0.9Sb0.1. We find small negative shifts (of order 100 ppm) in all three. In the insulator, the shift is nearly temperature independent, while in Bi and Sb it becomes more negative at low temperature without following the bulk susceptibility, suggesting two distinct temperature dependent contributions, possibly from the orbital and spin response. However, a simple model is unable to account for the observed shift. The spin-lattice relaxation differs in both scale and temperature dependence in all three. It is Korringa-like in Bi and remarkably is fastest in the insulating alloy and slowest in Sb with the highest bulk carrier density. These surprising results call for detailed calculations, but phenomenologically demonstrate that β -detected NMR of implanted 8Li+ is sensitive to the magnetic response of low-density carriers. The prospects for depth-resolved studies of conventional and topological surface states at lower implantation energies are good.

  6. In-situ Observation of Size and Irradiation Effects on Thermoelectric Properties of Bi-Sb-Te Nanowire in FIB Trimming

    PubMed Central

    Chien, Chia-Hua; Lee, Ping-Chung; Tsai, Wei-Han; Lin, Chien-Hung; Lee, Chih-Hao; Chen, Yang-Yuan

    2016-01-01

    In this report, the thermoelectric properties of a Bi0.8Sb1.2Te2.9 nanowire (NW) were in-situ studied as it was trimmed from 750 down to 490 and 285 nm in diameter by a focused ion beam. While electrical and thermal conductivities both indubitably decrease with the diameter reduction, the two physical properties clearly exhibit different diameter dependent behaviors. For 750 and 490 nm NWs, much lower thermal conductivities (0.72 and 0.69 W/m-K respectively) were observed as compared with the theoretical prediction of Callaway model. The consequence indicates that in addition to the size effect, extra phonon scattering of defects created by Ga ion irradiation was attributed to the reduction of thermal conductivities. As the NW was further trimmed down to 285 nm, both the electrical and thermal conductivities exhibited a dramatic reduction which was ascribed to the formation of amorphous structure due to Ga ion irradiation. The size dependence of Seebeck coefficient and figure of merit (ZT) show the maximum at 750 nm, then decrease linearly with size decrease. The study not only provides the thoroughly understanding of the size and defect effects on the thermoelectric properties but also proposes a possible method to manipulate the thermal conductivity of NWs via ion irradiation. PMID:27030206

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

    PubMed

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

    2015-02-20

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

  8. Defect studies in MBE grown GaSb{sub 1−x}Bi{sub x} layers

    SciTech Connect

    Segercrantz, N.; Kujala, J.; Tuomisto, F.; Slotte, J.; Song, Y.; Wang, S.

    2014-02-21

    Positron annihilation spectroscopy in Doppler broadening mode is used to study epitaxial layers of GaSb{sub 1−x}Bi{sub x} on undoped GaSb. The samples were grown by Molecular Beam Epitaxy at different temperatures and with different Bi/Sb beam equivalent pressure ratios resulting in Bi concentrations of 0–0.7 %. The results show a relationship between the growth parameters and Doppler broadening parameters. Incorporating Bi into GaSb decreases the vacancy concentration in the epitaxial layers compared to the sample with no Bi in the epitaxial layer.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. Mn-doped 0.15BiInO3-0.85PbTiO3 piezoelectric films deposited by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Lee, Sun Young; Ko, Song Won; Lee, Soonil; Trolier-McKinstry, Susan

    2012-05-01

    Undoped, 0.5 and 1.0 mol. % Mn-doped 0.15BiInO3-0.85PbTiO3 films were grown on PbTiO3/Pt/Ti/SiO2/Si substrates by pulsed laser deposition. Phase-pure perovskite films were obtained at a substrate temperature of 585 °C irrespective of Mn doping level. The 0.5 mol. % Mn-doped films showed a room temperature permittivity of 480 and a dielectric loss tangent of 0.015 at 100 kHz after 650 °C post-deposition annealing. The coercive field and remanent polarization were 80 kV/cm and 29 µC/cm2, respectively. The ferroelectric transition temperature of the films ranged from 535 to 585 °C. The e31,f piezoelectric coefficient was -7.1 C/m2. X-ray diffraction and phase transition temperature data showed that the Mn atoms substitute on the Ti-site as Mn3+; the resulting films have p-type conduction characteristics.

  11. Difference in expression patterns of placental cholesterol transporters, ABCA1 and SR-BI, in Meishan and Yorkshire pigs with different placental efficiency

    PubMed Central

    Hong, Linjun; Xu, Xiangdong; Huang, Ji; Lei, Minggang; Xu, Dequan; Zhao, Shuhong; Yu, Mei

    2016-01-01

    Cholesterol is a key cell membrane component and precursor of steroid hormones. The maternal cholesterol is an important exogenous cholesterol source for the developing embryos and its transportation is mediated by ABCA1 and SR-BI. Here we reported that during the peri-implantation period in pigs, ABCA1 was expressed by uterine luminal epithelium (LE) and interestingly, its expression was more abundantly in LE on mesometrial side of uterus. However, SR-BI was expressed primarily by LE, glandular epithelial cells (GE) and trophoblast cells (Tr). During the placentation period, the expression levels of ABCA1 and SR-BI proteins at epithelial bilayer and placental areolae were significantly higher in Chinese Meishan pigs compared to Yorkshire pigs. Consisitently, mRNA levels of HMGCR, the rate-limiting enzyme for cholesterol synthesis, were significantly higher in Meishan placentas than in Yorkshire placentas. Our findings revealed the routes of transplacental cholesterol transport mediated by ABCA1 and SR-BI in pigs and indicated that ABCA1 related pathway may participate in anchoring the conceptus to the mesometrial side of uterus. Additionally, an ABCA1 dependent compensatory mechanism related to the placental efficiency in response to the smaller placenta size in Meishan pigs was suggested. PMID:26852751

  12. Difference in expression patterns of placental cholesterol transporters, ABCA1 and SR-BI, in Meishan and Yorkshire pigs with different placental efficiency.

    PubMed

    Hong, Linjun; Xu, Xiangdong; Huang, Ji; Lei, Minggang; Xu, Dequan; Zhao, Shuhong; Yu, Mei

    2016-01-01

    Cholesterol is a key cell membrane component and precursor of steroid hormones. The maternal cholesterol is an important exogenous cholesterol source for the developing embryos and its transportation is mediated by ABCA1 and SR-BI. Here we reported that during the peri-implantation period in pigs, ABCA1 was expressed by uterine luminal epithelium (LE) and interestingly, its expression was more abundantly in LE on mesometrial side of uterus. However, SR-BI was expressed primarily by LE, glandular epithelial cells (GE) and trophoblast cells (Tr). During the placentation period, the expression levels of ABCA1 and SR-BI proteins at epithelial bilayer and placental areolae were significantly higher in Chinese Meishan pigs compared to Yorkshire pigs. Consisitently, mRNA levels of HMGCR, the rate-limiting enzyme for cholesterol synthesis, were significantly higher in Meishan placentas than in Yorkshire placentas. Our findings revealed the routes of transplacental cholesterol transport mediated by ABCA1 and SR-BI in pigs and indicated that ABCA1 related pathway may participate in anchoring the conceptus to the mesometrial side of uterus. Additionally, an ABCA1 dependent compensatory mechanism related to the placental efficiency in response to the smaller placenta size in Meishan pigs was suggested. PMID:26852751

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

    USGS Publications Warehouse

    Foord, Eugene E.; Shawe, Daniel R.

    1989-01-01

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

  14. Electronic band structure calculations of bismuth-antimony nanowires

    NASA Astrophysics Data System (ADS)

    Levin, Andrei; Dresselhaus, Mildred

    2012-02-01

    Alloys of bismuth and antimony received initial interest due to their unmatched low-temperature thermoelectric performance, and have drawn more recent attention as the first 3D topological insulators. One-dimensional bismuth-antimony (BiSb) nanowires display interesting quantum confinement effects, and are expected to exhibit even better thermoelectric properties than bulk BiSb. Due to the small, anisotropic carrier effective masses, the electronic properties of BiSb nanowires show great sensitivity to nanowire diameter, crystalline orientation, and alloy composition. We develop a theoretical model for calculating the band structure of BiSb nanowires. For a given crystalline orientation, BiSb nanowires can be in the semimetallic, direct semiconducting, or indirect semiconducting phase, depending on nanowire diameter and alloy composition. These ``phase diagrams'' turn out to be remarkably similar among the different orientations, which is surprising in light of the anisotropy of the bulk BiSb Fermi surface. We predict a novel direct semiconducting phase for nanowires with diameter less than ˜15 nm, over a narrow composition range. We also find that, in contrast to the bulk and thin film BiSb cases, a gapless state with Dirac dispersion cannot be realized in BiSb nanowires.

  15. Refinement of Mg{sub 2}Si reinforcement in a commercial Al–20%Mg{sub 2}Si in-situ composite with bismuth, antimony and strontium

    SciTech Connect

    Nordin, Nur Azmah; Farahany, Saeed Ourdjini, Ali; Abu Bakar, Tuty Asma; Hamzah, Esah

    2013-12-15

    Refinement by addition elements of Al–Mg{sub 2}Si alloys is known to result in a change of primary Mg{sub 2}Si morphology. In this paper, the effects of Bi, Sb and Sr on the characteristic parameters of Al–20%Mg{sub 2}Si in-situ composite have been investigated by computer aided cooling curve thermal analysis and microstructural inspection. Size, density and aspect ratio measurements showed that additions of 0.4 wt.% Bi, 0.8 wt.% Sb and 0.01 wt.% Sr refined the Mg{sub 2}Si reinforcement. Exceeding these concentrations, however, resulted in coarsening of Mg{sub 2}Si particles with no change in the morphology. The results also showed that addition elements caused a decrease in the nucleation and growth temperatures of Mg{sub 2}Si particles. The refining effect of Bi, Sb and Sr is likely to be related to the effect of oxide bifilms suspended in the composite melt as favored nucleation substrates for Mg{sub 2}Si particles. - Highlight: • 0.4 wt.%, 0.8 wt.% and 0.01 wt.% is the optimum content for Bi, Sb and Sr addition. • Exceeding optimum concentration resulted in the coarsening of reinforcements. • Nucleation and growth temperatures decrease with addition of Bi, Sb and Sr. • The refining effect of Bi, Sb and Sr is likely to be related to the oxide bifilms.

  16. Resistance noise in epitaxial thin films of ferromagnetic topological insulators

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Semonti; Kandala, Abhinav; Richardella, Anthony; Islam, Saurav; Samarth, Nitin; Ghosh, Arindam

    2016-02-01

    We report detailed temperature and gate-voltage dependence of 1/f resistance noise in magnetically doped topological insulators (TI) Crx(Bi,Sb)2-xTe3. The noise is remarkably sensitive to the gate voltage, increasing rapidly as the chemical potential is moved towards the charge neutrality point. Unlike in identically prepared (Bi,Sb)2Te3 films, where mobility-fluctuations in the surface states is the dominant mechanism, the noise in the magnetic Crx(Bi,Sb)2-xTe3 originates from transport in the localized band tail of the bulk valence band. A strong increase in noise with decreasing temperature supports this scenario. At higher temperature (≥10 K), we observed large noise peaks at gate voltage-dependent characteristic temperature scales. In line with similar observations in other non-magnetic TI systems, we attribute these peaks to generation-recombination in the Cr-impurity band.

  17. Optimizing proximity induced anomalous Hall effect in (BixSb1-x)2 Te3/YIG heterostructures

    NASA Astrophysics Data System (ADS)

    Jiang, Zilong; Tang, Chi; Shi, Jing; Chang, Cuizu; Wei, Peng; Moodera, Jagadeesh S.

    2015-03-01

    The spontaneously broken time reversal symmetry leads to an energy gap in the Dirac spectrum of the surface states of a topological insulator (TI) which gives rise to the quantized anomalous Hall effect (QAHE). QAHE has been observed in TI doped with Cr. Here we explore an alternative route by coupling the surface states of TI with yttrium iron garnet (YIG) ferrimagnetic insulator (FI). Just as in Cr-doped TI, a major challenge is to reduce the bulk conduction which overwhelms the surface state contribution. We have successfully grown 5 quintuple layer thick ternary TI (BixSb1-x)2 Te3 on atomically flat YIG films, in which the Fermi level of TI can be controlled by the Bi:Sb ratio. We have observed the anomalous Hall effect (AHE) in TI/YIG heterostructure over a wide range of carrier density and in both electron and hole types induced by varying the Bi:Sb ratio from 0:1 to 1:0. Both Rxx and RAH undergo systematic and dramatic changes as the Bi:Sb ratio is varied. The maximum RAH occurs near the p-n cross-over region at Bi:Sb ratio ~0.2:0.8, which is nearly two orders of magnitude greater than the minimum value at Bi:Sb ratio ~1:0. As the Bi:Sb ratio is varied, we find that RAH scales quadratically with Rxx, indicating the scattering rate independent AHE. The electric field effect study further demonstrates the existence of robust AHE while the Fermi level of TI is tuned. This research was supported by UC Lab fees program and a DOE/BES award at UCR, and by NSF/DMR at MIT.

  18. Corrosion behavior of Al-surface-treated steels in liquid Pb?Bi in a pot

    NASA Astrophysics Data System (ADS)

    Kurata, Y.; Futakawa, M.; Saito, S.

    2004-12-01

    Corrosion tests were performed in oxygen-saturated liquid Pb-Bi at 450 °C and 550 °C in a pot for 3000 h for Al-surface-treated steels containing various levels of Cr contents. The Al surface treatments were achieved using a gas diffusion method and a melt dipping method. Al2O3, FeAl2 and AlCr2 produced by the gas diffusion method exhibited corrosion resistance to liquid Pb-Bi, while the surface layer produced by the melt dipping method suffered a severe corrosion attack. Fe4Al13 and Fe2Al5 produced by the melt dipping method disappeared during the corrosion test at 550 °C and only FeAl remained.

  19. Bi atoms mobility-driven circular domains at the Bi/InAs(111) interface

    NASA Astrophysics Data System (ADS)

    Richter, M. C.; Mariot, J.-M.; Gafoor, M. A.; Nicolaï, L.; Heckmann, O.; Djukic, U.; Ndiaye, W.; Vobornik, I.; Fujii, J.; Barrett, N.; Feyer, V.; Schneider, C. M.; Hricovini, K.

    2016-09-01

    Bi films deposited on InAs(111) A and B sides have been studied by photoemission electron microscopy. A series of snapshots acquired during sequential annealing of the interfaces at temperatures below and above the melting temperature of Bi allowed obtaining a comprehensive image of the topographic and chemical evolutions of the Bi films that are found to be InAs side dependent. On the A side, a morphology of circular patterns controlled by Bi atoms mobility is observed. The patterns are formed on the pristine In-terminated InAs(111) surface covered by a weakly bonded Bi bilayer. On the B side, no particular morphology is observed due to a stronger chemical interaction between Bi and As atoms as evidenced by the spatially-resolved core-level photoelectron spectra.

  20. STM studies of topological phase transition in (Bi,In)2Se3

    NASA Astrophysics Data System (ADS)

    Zhang, Wenhan; Wang, Xueyun; Cheong, Sang-Wook; Wu, Weida; Weida Wu Team; Sang-Wook Cheong Collaboration

    Topological insulators (TI) are a class of materials with insulating bulk and metallic surface state, which is the result of band inversion induced by strong spin-orbit coupling (SOC). The transition from topological phase to non-topological phase is of great significance. In theory, topological phase transition is realized by tuning SOC strength. It is characterized by the process of gap closing and reopening. Experimentally it was observed in two systems: TlBi(S1-xSex)2 and (Bi1-xInx)2 Se3 where the transition is realized by varying isovalent elements doping concentration. However, none of the previous studies addressed the impact of disorder, which is inevitable in doped systems. Here, we present a systematic scanning tunneling microscopy/spectroscopy study on (Bi1-xInx)2 Se3 single crystals with different In concentrations across the transition. Our results reveal an electronic inhomogeneity due to the random distribution of In defects which locally suppress the topological surface states. Our study provides a new angle of understanding the topological transition in the presence of strong disorders. This work is supported by NSF DMR-1506618.

  1. Synthesis and Electronic Properties of Thermoelectric and Magnetic Nanoparticle Composite Materials

    NASA Astrophysics Data System (ADS)

    Koyano, Mikio; Kito, Daichi; Sakai, Kengo; Ariga, Tomoki

    2011-05-01

    Application of a magnetic field greatly enhances the thermoelectric efficiency of bismuth-antimony (Bi-Sb) alloys. We synthesized a hybrid of Bi-Sb alloy and magnetic nanoparticles, expecting improvement of the thermoelectric performance due to the magnetic field generated by the nanoparticles. Powder x-ray diffraction and magnetic measurements of the synthesized hybrid Bi0.88Sb0.12(FeSb)0.05 sample indicated that the ferromagnetic FeSb nanoparticles, with a size of about 30 nm, were distributed in the main phase of the Bi-Sb alloy. The FeSb nanoparticles act as soft ferromagnets in the diamagnetic host Bi-Sb alloy. The electrical resistivity ρ of the host Bi0.88Sb0.12 sample decreased concomitantly with decreasing temperature, showing a shoulder at 80 K. In contrast, ρ for the hybrid sample was enhanced below 100 K because of carrier scattering by the nanoparticles. The temperature dependence of the Seebeck coefficient S was also altered by the nanoparticle addition. In contrast, the addition of magnetic nanoparticles only slightly influenced the thermal conductivity κ. These results indicate that the addition of magnetic nanoparticles to thermoelectric materials modulates the electronic structures but does not influence the lattice system.

  2. Key Role for Scavenger Receptor B-I in the Integrative Physiology of Host Defense during Bacterial Pneumonia

    PubMed Central

    Gowdy, Kymberly M.; Madenspacher, Jennifer H.; Azzam, Kathleen M.; Gabor, Kristin A.; Janardhan, Kyathanahalli S.; Aloor, Jim J.; Fessler, Michael B.

    2014-01-01

    Scavenger receptor B-I (SR-BI) is a multirecognition receptor that regulates cholesterol trafficking and cardiovascular inflammation. Although it is expressed by neutrophils (PMNs) and lung-resident cells, no role for SR-BI has been defined in pulmonary immunity. Herein, we report that, compared to SR-BI+/+ counterparts, SR-BI−/− mice suffer markedly increased mortality during bacterial pneumonia associated with higher bacterial burden in lung and blood, deficient induction of the stress glucocorticoid corticosterone, higher serum cytokines, and increased organ injury. SR-BI−/− mice had significantly increased PMN recruitment and cytokine production in the infected airspace. This was associated with defective hematopoietic cell-dependent clearance of lipopolysaccharide from the airspace and increased cytokine production by SR-BI−/− macrophages. Corticosterone replacement normalized alveolar neutrophilia but not alveolar cytokines, bacterial burden, or mortality, suggesting that adrenal insufficiency derepresses PMN trafficking to the SR-BI−/− airway in a cytokine-independent manner. Despite enhanced alveolar neutrophilia, SR-BI−/− mice displayed impaired phagocytic killing. Bone marrow chimeras revealed this defect to be independent of the dyslipidemia and adrenal insufficiency of SR-BI−/− mice. During infection, SR-BI−/− PMNs displayed deficient oxidant production and CD11b externalization, and increased surface L-selectin, suggesting defective activation. Taken together, SR-BI coordinates several steps in the integrated neutrophilic host defense response to pneumonia. PMID:25336169

  3. Evaluation of the activity and molecular form of bi in cu smelting slags: Part I. ternary silicate slags

    NASA Astrophysics Data System (ADS)

    Marschman, S. C.; Lynch, D. C.

    1988-08-01

    The thermodynamic behavior of bismuth in the chemical systems associated with copper processing is not well understood. This study was designed to further the understanding of the physical chemistry of bismuth in slags that have similar compositions to those found in copper extractive metallurgical processing. The silicate system investigated was the FeO-Fe2O3-SiO2 ternary system in which bismuth was dissolved using an isopiestic experimental technique. Bismuth vapor pressures of 1 • 10-5 atm and 7.5 • 10-4 atm were used, and the silicates were equilibrated with this vapor at temperatures of 1458 K and 1523 K. In these experiments, the slag composition was varied such that P O 2 ranged from 10-12 to 10-8 atm. Bismuth was found to enter the silicate slag in both neutral and oxidic molecular forms. The oxidic form identified was that of BiO. The data suggest that the activity coefficient of neutral bismuth, γBi, is dependent on the solubility of that species in slag, even at the low concentrations observed in this study. It has been hypothesized, based on the large diameter of neutral Bi, that only a limited number of sites are available to accommodate neutral Bi, and that as the limit is approached γBi increases significantly. That hypothesis is shown to be consistent with the experimental results obtained in the present work as well as the results obtained by other investigators.

  4. Knockdown expression and hepatic deficiency reveal anatheroprotective role for SR-BI in liver and peripheral tissues

    SciTech Connect

    Huby, Thierry; Doucet, Chantal; Dachet, Christiane; Ouzilleau,Betty; Ueda, Yukihiko; Afzal, Veena; Rubin, Edward; Chapman, M. John; Lesnik, Philippe

    2006-07-18

    Scavenger receptor SR-BI has been implicated inHDL-dependent atheroprotective mechanisms. We report the generation of anSR-BI conditional knockout mouse model in which SR-BI gene targeting byloxP site insertion produced a hypomorphic allele (hypomSR-BI).Attenuated SR-BI expression in hypomSR-BI mice resulted in 2-foldelevation in plasma total cholesterol (TC) levels. Cre-mediated SR-BIgene inactivation of the hypomorphic SR-BI allele in hepatocytes(hypomSR-BI-KOliver) was associated with high plasma TC concentrations,increased plasma free cholesterol/TC (FC/TC) ratio, and alipoprotein-cholesterol profile typical of SR-BI-/- mice. Plasma TClevels were increased 2-fold in hypomSR-BI and control mice fed anatherogenic diet, whereas hypomSR-BI-KOliver and SR-BI-/- mice developedsevere hypercholesterolemia due to accumulation of FC-rich, VLDL-sizedparticles. Atherosclerosis in hypomSR-BI mice was enhanced (2.5-fold)compared with that in controls, but to a much lower degree than inhypomSR-BI-KOliver (32-fold) and SR-BI-/- (48-fold) mice. The lattermodels did not differ in either plasma lipid levels or in the capacity ofVLDL-sized lipoproteins to induce macrophage cholesterol loading.However, reduced atherosclerosis in hypomSR-BI-KOliver mice wasassociated with decreased lesional macrophage content as compared withthat in SR-BI-/- mice. These data imply that, in addition to its majoratheroprotective role in liver, SR-BI may exert an antiatherogenic rolein extrahepatic tissues.

  5. Knockdown expression and hepatic deficiency reveal an atheroprotective role for SR-BI in liver and peripheral tissues

    PubMed Central

    Huby, Thierry; Doucet, Chantal; Dachet, Christiane; Ouzilleau, Betty; Ueda, Yukihiko; Afzal, Veena; Rubin, Edward; Chapman, M. John; Lesnik, Philippe

    2006-01-01

    Scavenger receptor SR-BI has been implicated in HDL-dependent atheroprotective mechanisms. We report the generation of an SR-BI conditional knockout mouse model in which SR-BI gene targeting by loxP site insertion produced a hypomorphic allele (hypomSR-BI). Attenuated SR-BI expression in hypomSR-BI mice resulted in 2-fold elevation in plasma total cholesterol (TC) levels. Cre-mediated SR-BI gene inactivation of the hypomorphic SR-BI allele in hepatocytes (hypomSR-BI–KOliver) was associated with high plasma TC concentrations, increased plasma free cholesterol/TC (FC/TC) ratio, and a lipoprotein-cholesterol profile typical of SR-BI–/– mice. Plasma TC levels were increased 2-fold in hypomSR-BI and control mice fed an atherogenic diet, whereas hypomSR-BI–KOliver and SR-BI–/– mice developed severe hypercholesterolemia due to accumulation of FC-rich, VLDL-sized particles. Atherosclerosis in hypomSR-BI mice was enhanced (2.5-fold) compared with that in controls, but to a much lower degree than in hypomSR-BI–KOliver (32-fold) and SR-BI–/– (48-fold) mice. The latter models did not differ in either plasma lipid levels or in the capacity of VLDL-sized lipoproteins to induce macrophage cholesterol loading. However, reduced atherosclerosis in hypomSR-BI–KOliver mice was associated with decreased lesional macrophage content as compared with that in SR-BI–/– mice. These data imply that, in addition to its major atheroprotective role in liver, SR-BI may exert an antiatherogenic role in extrahepatic tissues. PMID:16964311

  6. Distribution of Be, Al, Se and Bi in the surface waters of the western North Atlantic and Caribbean

    NASA Astrophysics Data System (ADS)

    Measures, C. I.; Grant, B.; Khadem, M.; Lee, D. S.; Edmond, J. M.

    1984-11-01

    The mixed layer distributions of several trace elements have been determined along a detailed transect from Rhode Island to the Panama Canal. When taken together with a new and existing profile data from the North Atlantic and North Pacific, some general inferences emerge as to the processes controlling their concentrations in the surface waters. The large enrichments in Be observed in the upper waters of the North Atlantic relative to the North Pacific appear to be sustained mainly by fluvial inputs. Those of Se are derived from atmospheric transport. Aluminium and Bi also appear to have an aeolian source in the Sargasso Sea. However, in the tropical eastern Pacific, the Al input may be fluvial On this cruise, Be, Al and the Se species were analyzed on board ship within a few hours of collection. The demonstration that this is feasible opens up the prospect of the application of large-scale chemical hydrography to the study of the processes controlling the distribution and water column variability of trace elements in the oceans.

  7. Thickness Dependence of the Quantum Anomalous Hall Effect in Magnetic Topological Insulator Films.

    PubMed

    Feng, Xiao; Feng, Yang; Wang, Jing; Ou, Yunbo; Hao, Zhenqi; Liu, Chang; Zhang, Zuocheng; Zhang, Liguo; Lin, Chaojing; Liao, Jian; Li, Yongqing; Wang, Li-Li; Ji, Shuai-Hua; Chen, Xi; Ma, Xucun; Zhang, Shou-Cheng; Wang, Yayu; He, Ke; Xue, Qi-Kun

    2016-08-01

    The evolution of the quantum anomalous Hall effect with the thickness of Cr-doped (Bi,Sb)2 Te3 magnetic topological insulator films is studied, revealing how the effect is caused by the interplay of the surface states, band-bending, and ferromagnetic exchange energy. Homogeneity in ferromagnetism is found to be the key to high-temperature quantum anomalous Hall material. PMID:27166762

  8. Magnetic modulation doping in topological insulators toward higher-temperature quantum anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Mogi, M.; Yoshimi, R.; Tsukazaki, A.; Yasuda, K.; Kozuka, Y.; Takahashi, K. S.; Kawasaki, M.; Tokura, Y.

    2015-11-01

    Quantum anomalous Hall effect (QAHE), which generates dissipation-less edge current without external magnetic field, is observed in magnetic-ion doped topological insulators (TIs) such as Cr- and V-doped (Bi,Sb)2Te3. The QAHE emerges when the Fermi level is inside the magnetically induced gap around the original Dirac point of the TI surface state. Although the size of gap is reported to be about 50 meV, the observable temperature of QAHE has been limited below 300 mK. We attempt magnetic-Cr modulation doping into topological insulator (Bi,Sb)2Te3 films to increase the observable temperature of QAHE. By introducing the rich-Cr-doped thin (1 nm) layers at the vicinity of both the surfaces based on non-Cr-doped (Bi,Sb)2Te3 films, we have succeeded in observing the QAHE up to 2 K. The improvement in the observable temperature achieved by this modulation-doping appears to be originating from the suppression of the disorder in the surface state interacting with the rich magnetic moments. Such a superlattice designing of the stabilized QAHE may pave a way to dissipation-less electronics based on the higher-temperature and zero magnetic-field quantum conduction.

  9. Magnetic modulation doping in topological insulators toward higher-temperature quantum anomalous Hall effect

    SciTech Connect

    Mogi, M. Yoshimi, R.; Yasuda, K.; Kozuka, Y.; Tsukazaki, A.; Takahashi, K. S.; Kawasaki, M.; Tokura, Y.

    2015-11-02

    Quantum anomalous Hall effect (QAHE), which generates dissipation-less edge current without external magnetic field, is observed in magnetic-ion doped topological insulators (TIs) such as Cr- and V-doped (Bi,Sb){sub 2}Te{sub 3}. The QAHE emerges when the Fermi level is inside the magnetically induced gap around the original Dirac point of the TI surface state. Although the size of gap is reported to be about 50 meV, the observable temperature of QAHE has been limited below 300 mK. We attempt magnetic-Cr modulation doping into topological insulator (Bi,Sb){sub 2}Te{sub 3} films to increase the observable temperature of QAHE. By introducing the rich-Cr-doped thin (1 nm) layers at the vicinity of both the surfaces based on non-Cr-doped (Bi,Sb){sub 2}Te{sub 3} films, we have succeeded in observing the QAHE up to 2 K. The improvement in the observable temperature achieved by this modulation-doping appears to be originating from the suppression of the disorder in the surface state interacting with the rich magnetic moments. Such a superlattice designing of the stabilized QAHE may pave a way to dissipation-less electronics based on the higher-temperature and zero magnetic-field quantum conduction.

  10. Structure and transport of topological insulators on epitaxial graphene

    NASA Astrophysics Data System (ADS)

    Kally, James; Reifsnyder Hickey, Danielle; Lin, Yu-Chuan; Richardella, Anthony; Lee, Joon Sue; Robinson, Joshua; Mkhoyan, K. Andre; Samarth, Nitin

    Recent advancements in spintronics have shown that a class of materials, topological insulators (TI), can be used as a spin-current generator or detector. Topological insulators have protected surface states with the electron's spin locked to its momentum. To access these surface states, (Bi, Sb)2Te3 can be grown by molecular beam epitaxy to have the Fermi energy near the Dirac point so that transport occurs only through the spin-dependent surface states. Graphene is another 2D material of great interest for spintronics because of its very long spin diffusion length. This is an ideal material to act as a spin channel in devices. The van der Waals nature of the growth exhibited by 2D materials such as (Bi, Sb)2Te3 and graphene allows heterostructures to be formed despite the large lattice mismatch. We explore the structure and transport of (Bi, Sb)2Te3 grown on epitaxial graphene on 6H-SiC substrates for spintronic applications. This work was supported in part by C-SPIN and LEAST, two of the six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA.

  11. Influence of Ce substitution for Bi in BiVO4 and the impact on the phase evolution and microwave dielectric properties.

    PubMed

    Zhou, Di; Pang, Li-Xia; Guo, Jing; Qi, Ze-Ming; Shao, Tao; Wang, Qiu-Ping; Xie, Hui-Dong; Yao, Xi; Randall, Clive A

    2014-01-21

    In the present work, the (Bi1-xCex)VO4 (x ≤ 0.6) ceramics were prepared via a solid-state reaction method and all the ceramic samples could be densified below 900 °C. From the X-ray diffraction analysis, it is found that a monoclinic scheelite solid solution can be formed in the range x ≤ 0.10. In the range 0.20 ≤ x ≤ 0.60, a composite region with both monoclinic scheelite and tetragonal zircon solid solutions was formed and the content of the zircon phase increased with the calcined or sintering temperature. The refined lattice parameters of (Bi0.9Ce0.1)VO4 are a = 5.1801(0) Å, b = 5.0992(1) Å, c = 11.6997(8) Å, and γ = 90.346(0)° with the space group I112/b(15). The VO4 tetrahedron contracts with the substitution of Ce for Bi at the A site, and this helps to keep the specific tetrahedron chain stable in the monoclinic structure. The microwave dielectric permittivity was found to decrease linearly from 68 to about 26.6; meanwhile, the quality factor (Qf) value increased from 8000 GHz to around 23900 GHz as the x value increased from 0 to 0.60. The best microwave dielectric properties were obtained in a (Bi0.75Ce0.25)VO4 ceramic with a permittivity of ∼47.9, a Qf value of ∼18000 GHz, and a near-zero temperature coefficient of ∼+15 ppm/°C at a resonant frequency of around 7.6 GHz at room temperature. Infrared spectral analysis supported that the dielectric contribution for this system at microwave region could be attributed to the absorptions of structural phonon oscillations. This work presents a novel method to modify the temperature coefficient of BiVO4-type materials. This system of microwave dielectric ceramic might be an interesting candidate for microwave dielectric resonator and low-temperature cofired ceramic technology applications. PMID:24392840

  12. Lead, Ba and Bi in Antarctic Law Dome ice corresponding to the 1815 AD Tambora eruption: an assessment of emission sources using Pb isotopes

    NASA Astrophysics Data System (ADS)

    Vallelonga, P.; Candelone, J.-P.; Van de Velde, K.; Curran, M. A. J.; Morgan, V. I.; Rosman, K. J. R.

    2003-06-01

    Lead, Ba and Bi concentrations and Pb isotopic compositions have been measured in Antarctic Law Dome (66.8°S, 112.4°E) ice dated from 1814 AD to 1819 AD by thermal ionisation mass spectrometry to investigate the possible deposition of heavy metals from the 1815 AD eruption of Tambora volcano (8.5°S, 117.4°E) in Indonesia. Although volcanic S emissions from Tambora (observed as SO 42-) are present in the Antarctic ice core record, there are grounds to question the origin of the Pb and Bi also deposited at Law Dome from late 1817, as the Pb isotope data suggest this Pb originated from Mount Erebus (77.5°S, 167.2°E) on Ross Island, Antarctica. It is shown that at least 97% of any Pb and Bi emitted from Tambora was removed from the atmosphere within the 1.6 year period required to transport aerosols from Indonesia to Antarctica. Consequently, increased Pb and Bi concentrations observed in Law Dome ice about 1818 AD are attributed to either increased heavy metal emissions from Mount Erebus, or increased fluxes of heavy metals to the Antarctic ice sheet resulting from climate and meteorological modifications following the Tambora eruption. Elevated Ba concentrations, observed from mid-1816 to mid-1818, indicate increased atmospheric loading of rock and soil dust also occurred at the time.

  13. L{sub 3}-subshell alignment of Au and Bi in collisions with 12-55-MeV carbon ions

    SciTech Connect

    Kumar, Ajay; Choudhury, R. K.; Agnihotri, A. N.; Chatterjee, S.; Misra, D.; Tribedi, L. C.; Kasthurirangan, S.; Sarkadi, L.

    2010-06-15

    Angular distribution of the L x-ray intensities in Au and Bi induced by 12-55-MeV carbon ions has been measured. The L{sub {alpha}}, L{sub {beta}}, and L{sub {gamma}} x-ray intensities were found to be isotropic within experimental uncertainty. The alignment parameter A{sub 20} of the L{sub 3} (2p{sub 3/2}) subshell was deduced from the measured anisotropy parameter {beta} value of the well-resolved L{sub l} line, obtained from the angular distribution of the I{sub Ll}/I{sub L{alpha}}, I{sub Ll}/I{sub L{beta}}, and I{sub Ll}/I{sub L{gamma}} x-ray intensity ratios. The measured A{sub 20} values have been compared with those obtained using theoretical models that involve the plane-wave Born approximation; projectile's energy loss and its Coulomb deflection from the straight-line trajectory, perturbed-stationary-state, and relativistic effects (ECPSSR); and ECPSSR with the intrashell effect.

  14. Composites of Bi{sub 2-x}Sb{sub x}Te{sub 3} nanocrystals and fullerene molecules for thermoelectricity

    SciTech Connect

    Kulbachinskii, V.A.; Kytin, V.G.; Popov, M.Yu.; Buga, S.G.; Stepanov, P.B.; Blank, V.D.

    2012-09-15

    New nanocomposite thermoelectric material composed from nanocrystallites of Bi-Sb-Te alloys covered by C{sub 60} molecules has been synthesized and studied. An increase of fullerene content leads to the growth of hole concentration in p-type materials and reduction of electron concentration in n-type materials. The fullerene molecules provide additional scattering of phonons reducing lattice heat conductivity. Reduction of heat conductivity exceeds the reduction of electrical conductivity for fullerene content less than 0.5 volume % and essential enhances the thermoelectric figure of merit. The maximum value of thermoelectric figure of merit equals to 1.17 at 450 K was observed in Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} composite containing 0.5 volume % C{sub 60} molecules. The experimental results were analyzed in a frame of the model based on the Boltzmann equation. The analysis considers light and heavy electrons and holes and accounts the intervalley scattering of charge carriers. The calculations of the kinetic coefficients shows that the improvement of the thermoelectric figure of merit originates from the reduction of the lattice heat conductivity caused by fullerene molecules. The dependencies of the thermoelectric figure of merit on the acceptor concentration were calculated. - Graphical abstract: New nanocomposite thermoelectric material composed from nanocrystallites of Bi-Sb-Te alloys covered by C{sub 60} molecules has been synthesized and studied. An increase of fullerene content leads to the growth of hole concentration in p-type materials and reduction of electron concentration in n-type materials. The fullerene molecules provide additional scattering of phonons reducing lattice heat conductivity and enhances the thermoelectric figure of merit. The maximum value of thermoelectric figure of merit equal to 1.17 at 450 K was observed in Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} composite containing 0.5 volume % fullerene molecules. Simulations of thermoelectric

  15. Selenium, tellurium and precious metal mineralogy in Uchalinsk copper-zinc-pyritic district, the Urals

    NASA Astrophysics Data System (ADS)

    Vikentev, I.

    2016-04-01

    During processing the most of Au, Ag, Se, Te, Pb, Bi, Sb, Hg as well as notable part of Cu, Zn and Cd fail for tailings and became heavy metal pollutants. Modes of occurrence of Au, Ag, Te and Se covers two giant VMS deposits: Uchaly (intensively deformed) and Uzelginsk (altered by late hydrothermal processes) as well as middle-sized Molodezn and West Ozern deposits (nondeformed) have been studied. Mineral forms of these elements as well as their presence in disperse mode in common ore minerals (pyrite, chalcopyrite, sphalerite) have been studied using SEM, EPMA, INAA, ICP-MS and LA-ICP-MS.

  16. Radioisotope space power generator. Annual report, October 1978-September 1979

    SciTech Connect

    Elsner, N.B.; Chin, J.; Staley, H.G.; Bass, J.C.; Morris, C.C.; Shearer, C.H.; Steeger, E.J.

    1982-03-01

    The emphasis of the Isotec Technology Program shifted from development of a Galileo generator to study of a segmented selenide element and couple technology. The goal of the FY 79 program was to determine the feasibility of fabricating segmented selenide P and N elements which exploit the high thermoelectric efficiency of (Cu,Ag)/sub 2/Se and Gd/sub 2/Se/sub 3/ materials. A preliminary evaluation of segmented element efficiencies, material compatibilities, and fabrication abilities was used to select (Cu,Ag)/sub 2/Se/Fe(Bi,Sb)/sub 2/Te/sub 3/ for the P element and Gd/sub 2/Se/sub 3//PbTe for the N element. The iron barrier between the (Cu,Ag)/sub 2/Se and (Bi,Sb)/sub 2/Te/sub 3/ prevented degradation of thermoelectric properties from copper contamination of the (Bi,Sb)/sub 2/Te/sub 3/. Fabrication processes for both elements were developed. Gd/sub 2/Se/sub 3/ was friable and difficult to fabricate crack-free. It also exhibited a phase transition from cubic to orthorhombic, which increased its susceptibility to microcracking and reduced its thermoelectric efficiency. Life testing of an all-bonded couple with unsegmented (Cu,Ag)/sub 2/Se P-type and Gd/sub 2/Se/sub 3/ N-type elements was stopped after 3300 h in a nominal 830/sup 0/C/390/sup 0/C thermal gradient. The Gd/sub 2/Se/sub 3/ leg did not show any significant degradation during the test. Examination of the hot end of the P element showed the need for a less reactive hot cap material and an improved vapor supression system. Module testing of a 1-W (Bi,Sb)/sub 2/(Se,Te)/sub 3/ generator was performed for 5000 h with no degradation in power. High-temperature Thermid 600 adhesive curing cycles were examined, 75-mW module loading tests were performed, and diagnostic examination of RTG-2A and RTG-201 was completed.

  17. New type of multijunction thermopile IR detector

    NASA Astrophysics Data System (ADS)

    Sun, Tietun; Guo, Lihui

    1996-09-01

    A newly designed thin-film thermopile infrared detector, which as an absorption layer and a sensitive area on two sides are fabricated using integrated-circuit technology. The device uses a series-connected thermocouples array whose `hot' junction are supported on a thin Myler film of 1 - 3 micrometers thickness. By a special method of fasting the shadow mask, the thermopile with 48 Bi-Sb couples for 2 X 2 mm(superscript 2) area produces a responsivity of 50 - 70 V/W and relaxation time of about 70 ms.

  18. Material compatibility and thermal aging of thermoelectric materials.

    SciTech Connect

    Gardea, Andrew D.; Nishimoto, Ryan; Yang, Nancy Y. C.; Morales, Alfredo Martin; Whalen, Scott A.; Chames, Jeffrey M.; Clift, W. Miles

    2009-09-01

    In order to design a thermoelectric (TE) module suitable for long-term elevated temperature use, the Department 8651 has conducted parametric experiments to study material compatibility and thermal aging of TE materials. In addition, a comprehensive material characterization has been preformed to examine thermal stability of P- and N-based alloys and their interaction with interconnect diffusion barrier(s) and solder. At present, we have completed the 7-days aging experiments for 36 tiles, from ambient to 250 C. The thermal behavior of P- and N-based alloys and their thermal interaction with both Ni and Co diffusion barriers and Au-Sn solder were examined. The preliminary results show the microstructure, texture, alloy composition, and hardness of P-(Bi,Sb){sub 2}Te{sub 3} and N-Bi{sub 2}(Te,Se){sub 3} alloys are thermally stable up to 7 days annealing at 250 C. However, metallurgical reactions between the Ni-phosphor barriers and P-type base alloy were evident at temperatures {ge} 175 C. At 250 C, the depth (or distance) of the metallurgical reaction and/or Ni diffusion into P-(Bi,Sb){sub 2}Te{sub 3} is approximately 10-15 {micro}m. This thermal instability makes the Ni-phosphor barrier unsuitable for use at temperatures {ge} 175 C. The Co barrier appeared to be thermally stable and compatible with P(Bi,Sb){sub 2}Te{sub 3} at all annealing temperatures, with the exception of a minor Co diffusion into Au-Sn solder at {ge} 175 C. The effects of Co diffusion on long-term system reliability and/or the thermal stability of the Co barrier are yet to be determined. Te evaporation and its subsequent reaction with Au-Sn solder and Ni and Co barriers on the ends of the tiles at temperatures {ge} 175 C were evident. The Te loss and its effect on the long-term required stoichiometry of P-(Bi, Sb){sub 2}Te{sub 3} are yet to be understood. The aging experiments of 90 days and 180 days are ongoing and scheduled to be completed in 30 days and 150 days, respectively. Material

  19. COEXISTING GALENA, PbS//S//S AND SULFOSALTS: EVIDENCE FOR MULTIPLE EPISODES OF MINERALIZATION IN THE ROUND MOUNTAIN AND MANHATTAN GOLD DISTRICTS, NEVADA.

    USGS Publications Warehouse

    Foord, Eugene E.; Shawe, Daniel R.; Conklin, Nancy M.

    1988-01-01

    Studies of galena and Pb-Bi-Ag-Cu(Hg) sulfosalts of varied compositions in the Round Mountain and Manhattan gold districts of Nevada corroborate the occurrence of several distinct mineralized systems characterized by different mineral compositions and assemblages. The different episodes of mineralization are related to different Cretaceous and Tertiary magmatic-hydrothermal events, although the assignment of specific mineral compositions and associations with dated mineralized systems is still incomplete. At the Fairview mine, galena associated with Pb-Bi-Ag sulfosalts and simple sulfides occurs as intergrowths of discretely different composition controlled by silver and bismuth content. A galena-type phase (Pbs//s//s) with solid solution toward matildite, AgBiS//2(composition Gal//6//0Mat//4//0) was found. If silver and, to a lasser extent, bismuth are absent, the galena formed will be almost pure PbS. Some minor antimony may substitute for bismuth. This study confirms a linear relationship between a cell edge and Ag-Bi(Sb) content for galena containing less than about 15 wt. percent Ag and Bi(Sb).

  20. Mechanisms of Si and Ge diffusion on surfactant terminated (111) silicon and germanium surfaces

    NASA Astrophysics Data System (ADS)

    Zhachuk, R.; Coutinho, J.

    2016-05-01

    Surfactant mediated growth of Ge layers and formation of small Ge clusters on Si(111) are promising assemblage processes with envisioned applications in areas such as nanoelectronics or photovoltaics. They critically depend on migration of Si and Ge adatoms on surfactant terminated Si(111) and Ge(111) surfaces. We address Si and Ge adsorption and migration on surfactant (Bi, Sb) terminated (111) surfaces of Si and strained Ge by comprehensively mapping potential energy surfaces using density functional calculations. The main migration paths are identified and corresponding energy barriers are reported. It is shown that the energy barrier for adatom migration through Bi or Sb surfactant trimers (by actually breaking the trimers) is virtually degenerate to the mechanism involving traveling of the adatom around the same surfactant structures. We also find a low-energy anchoring site that is suggested to act as a nucleation structure and to trigger the clustering process. These results suggest a fundamentally new picture for the whole Si(111)sbnd Bi(Sb) epitaxial process.

  1. Surface-State-Dominated Spin-Charge Current Conversion in Topological-Insulator-Ferromagnetic-Insulator Heterostructures

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Kally, James; Lee, Joon Sue; Liu, Tao; Chang, Houchen; Hickey, Danielle Reifsnyder; Mkhoyan, K. Andre; Wu, Mingzhong; Richardella, Anthony; Samarth, Nitin

    2016-08-01

    We report the observation of ferromagnetic resonance-driven spin pumping signals at room temperature in three-dimensional topological insulator thin films—Bi2Se3 and (Bi,Sb ) 2Te3 —deposited by molecular beam epitaxy on Y3 Fe5 O12 thin films. By systematically varying the Bi2 Se3 film thickness, we show that the spin-charge conversion efficiency, characterized by the inverse Rashba-Edelstein effect length (λIREE ), increases dramatically as the film thickness is increased from two quintuple layers, saturating above six quintuple layers. This suggests a dominant role of surface states in spin and charge interconversion in topological-insulator-ferromagnet heterostructures. Our conclusion is further corroborated by studying a series of Y3 Fe5 O12 /(Bi,Sb ) 2Te3 heterostructures. Finally, we use the ferromagnetic resonance linewidth broadening and the inverse Rashba-Edelstein signals to determine the effective interfacial spin mixing conductance and λIREE.

  2. Electrochemically deposited BiTe-based nanowires for thermoelectric applications

    SciTech Connect

    Ng, Inn-Khuan; Kok, Kuan-Ying; Rahman, Che Zuraini Che Ab; Saidin, Nur Ubaidah; Ilias, Suhaila Hani; Choo, Thye-Foo

    2014-02-12

    Nanostructured materials systems such as thin-films and nanowires (NWs) are promising for thermoelectric power generation and refrigeration compared to traditional counterparts in bulk, due to their enhanced thermoelectric figures-of-merit. BiTe and its derivative compounds, in particular, are well-known for their near-room temperature thermoelectric performance. In this work, both the binary and ternary BiTe-based nanowires namely, BiTe and BiSbTe, were synthesized using template-assisted electrodeposition. Diameters of the nanowires were controlled by the pore sizes of the anodised alumina (AAO) templates used. Systematic study on the compositional change as a function of applied potential was carried out via Linear Sweep Voltanmetry (LSV). Chemical compositions of the nanowires were studied using Energy Dispersive X-ray Spectrometry (EDXS) and their microstructures evaluated using diffraction and imaging techniques. Results from chemical analysis on the nanowires indicated that while the Sb content in BiSbTe nanowires increased with more negative deposition potentials, the formation of Te{sup 0} and Bi{sub 2}Te{sub 3} were favorable at more positive potentials.

  3. Brittle thermoelectric semiconductors extrusion under high hydrostatic pressure

    SciTech Connect

    Sidorenko, N.A.

    1994-08-10

    Origins of strength increase of brittle materials like thermoelectric (TE) semiconductors during plastic deformation under high external pressure are analyzed. TE material stressed state in the process of extrusion is reviewed. Plastic deformation of monocrystalline TE material billet produced by extrusion under sufficiently high external hydrostatic pressure is more uniform than under ordinary ambient pressure and can lead to crack free extruded TE material structure, crystallographic symmetry of which coincides with original billet one. Experimental device realized the scheme of extrusion under high hydrostatic pressure is described. Here extrusion are carrying out in compressed liquid medium. The developed device ensures the value of hydrostatic pressure up to 2 GPa and extrusion temperature interval 300--600 K. Properties of extruded Bi-Sb and Bi-Sb-Te single crystals are also reviewed. Possible application of presented method of extrusion under high hydrostatic pressure to form TE branches with highly accurate cross section for miniature TE coolers or generators is discussed. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  4. Micromachined Thermoelectric Sensors and Arrays and Process for Producing

    NASA Technical Reports Server (NTRS)

    Foote, Marc C. (Inventor); Jones, Eric W. (Inventor); Caillat, Thierry (Inventor)

    2000-01-01

    Linear arrays with up to 63 micromachined thermopile infrared detectors on silicon substrates have been constructed and tested. Each detector consists of a suspended silicon nitride membrane with 11 thermocouples of sputtered Bi-Te and Bi-Sb-Te thermoelectric elements films. At room temperature and under vacuum these detectors exhibit response times of 99 ms, zero frequency D* values of 1.4 x 10(exp 9) cmHz(exp 1/2)/W and responsivity values of 1100 V/W when viewing a 1000 K blackbody source. The only measured source of noise above 20 mHz is Johnson noise from the detector resistance. These results represent the best performance reported to date for an array of thermopile detectors. The arrays are well suited for uncooled dispersive point spectrometers. In another embodiment, also with Bi-Te and Bi-Sb-Te thermoelectric materials on micromachined silicon nitride membranes, detector arrays have been produced with D* values as high as 2.2 x 10(exp 9) cm Hz(exp 1/2)/W for 83 ms response times.

  5. Magnetic ordering and quantum anomalous Hall phase of Cr-doped topological insulators: First principles studies

    NASA Astrophysics Data System (ADS)

    Kim, Jeongwoo; Jhi, Seung-Hoon; Wu, Ruqian

    Realization of transverse electric currents without external magnetic fields, so called the quantum anomalous Hall effect (QAHE), is achieved in Cr-doped topological insulating (Bi,Sb)2Te3 compounds. However, detailed mechanism of QAHE and magnetic ordering in topological insulators (TIs) is still unclear with several models in controversy. We study the origin of QAHE in magnetic impurity-doped TIs using first-principles calculations. We investigate a possibility of the quantum anomalous Hall phase in conventional three-dimensional topological insulators, such as Bi2Se3, Bi2Te3, and Sb2Te3. We find that Sb2Te3 is the most suitable compound for realizing QAHE, because it maintains insulating phase and relatively strong ferromagnetic ordering in a wide range of Cr doping while Bi2Se3 and Bi2Te3 become metallic even by a small amount of Cr doping. Contrary to previous predictions, the kinetic exchange is responsible for the magnetic phase of Cr-doped TIs and it induces spin-polarized valence and conduction bands in Sb2Te3. We also discuss the role of Bi doping in topological surfaces states of Cr-doped Sb2Te3, which leads to QAHE in (Bi,Sb)2Te3. Work was supported as part of the SHINES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. SC0012670.

  6. Surface-State-Dominated Spin-Charge Current Conversion in Topological-Insulator-Ferromagnetic-Insulator Heterostructures.

    PubMed

    Wang, Hailong; Kally, James; Lee, Joon Sue; Liu, Tao; Chang, Houchen; Hickey, Danielle Reifsnyder; Mkhoyan, K Andre; Wu, Mingzhong; Richardella, Anthony; Samarth, Nitin

    2016-08-12

    We report the observation of ferromagnetic resonance-driven spin pumping signals at room temperature in three-dimensional topological insulator thin films-Bi_{2}Se_{3} and (Bi,Sb)_{2}Te_{3}-deposited by molecular beam epitaxy on Y_{3}Fe_{5}O_{12} thin films. By systematically varying the Bi_{2}Se_{3} film thickness, we show that the spin-charge conversion efficiency, characterized by the inverse Rashba-Edelstein effect length (λ_{IREE}), increases dramatically as the film thickness is increased from two quintuple layers, saturating above six quintuple layers. This suggests a dominant role of surface states in spin and charge interconversion in topological-insulator-ferromagnet heterostructures. Our conclusion is further corroborated by studying a series of Y_{3}Fe_{5}O_{12}/(Bi,Sb)_{2}Te_{3} heterostructures. Finally, we use the ferromagnetic resonance linewidth broadening and the inverse Rashba-Edelstein signals to determine the effective interfacial spin mixing conductance and λ_{IREE}. PMID:27563980

  7. Mapping the chemical potential dependence of current-induced spin polarization in a topological insulator

    NASA Astrophysics Data System (ADS)

    Lee, Joon Sue; Richardella, Anthony; Hickey, Danielle Reifsnyder; Mkhoyan, K. Andre; Samarth, Nitin

    2015-10-01

    We report electrical measurements of the current-induced spin polarization of the surface current in topological insulator devices where contributions from bulk and surface conduction can be disentangled by electrical gating. The devices use a ferromagnetic tunnel junction (permalloy/Al 2O3 ) as a spin detector on a back-gated (Bi,Sb ) 2Te3 channel. We observe hysteretic voltage signals as the magnetization of the detector ferromagnet is switched parallel or antiparallel to the spin polarization of the surface current. The amplitude of the detected voltage change is linearly proportional to the applied dc bias current in the (Bi,Sb ) 2Te3 channel. As the chemical potential is tuned from the bulk bands into the surface state band, we observe an enhancement of the spin-dependent voltages up to 300% within the range of the electrostatic gating. Using a simple model, we extract the spin polarization near charge neutrality (i.e., the Dirac point).

  8. Characterization of La-doped xBiInO3(1 ‑ x)PbTiO3 Piezoelectric Films Deposited by the Radio-Frequency Magnetron Sputtering Method

    NASA Astrophysics Data System (ADS)

    Ke-Xue, Sun; Shu-Yi, Zhang; Kiyotaka, Wasa; Xiu-Ji, Shui

    2016-06-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 11174142 and 11304160, the National Basic Research Program of China under Grant No 2012CB921504, and the Special Fund for Public Interest of China under Grant No 201510068.

  9. Topological Spintronics: Materials, Phenomena and Devices

    NASA Astrophysics Data System (ADS)

    Samarth, Nitin

    2015-03-01

    The two-dimensional surface states of three-dimensional topological insulators such as Bi2Se3and(Bi,Sb)2Te3 possess a spin texture that can potentially be exploited for spintronics applications. We provide a perspective on the emergence of ``topological spintronics,'' demonstrating how this spin texture can be engineered using either quantum tunneling between surfaces or by breaking time-reversal symmetry. We then discuss recent experiments that show striking spintronic phenomena useful for proof-of-concept devices, including a spin-orbit torque of record efficiency at room temperature and an electrically-gated ``giant anisotropic magnetoresistance'' at low temperature. This work was carried out in collaboration with A. Richardella, S.-Y. Xu, M. Neupane, A. Mellnik, A. Kandala, J. S. Lee, D. M. Zhang, M. Z. Hasan and D. C. Ralph. We acknowledge funding from the DARPA Meso program, ONR and C-SPIN (under sponsorship of MARCO and DARPA).

  10. Measurement of Local Peltier Constant at a Microcontact

    NASA Astrophysics Data System (ADS)

    Koyano, Mikio; Akashi, Naoya

    2009-07-01

    Our novel apparatus measures the local Peltier constant at a thermoelectric material microregion. A narrow metal needle probe contacts a sample mounted into a small adiabatic vacuum chamber with a pressure of about 10-4 Pa. A␣stepping-motor-type nano-actuator controls the probe’s contact pressure. We measured DC and AC I- V characteristics at the microcontact to determine thermoelectric properties. We measured I- V characteristics between the probe and a commercial (Bi,Sb)2Te3 surface. Measured values of local Peltier constants are of the same order as the bulk Peltier constant π: ca. 55 mV. They increase with increased contact resistance, suggesting that contact size affects thermoelectricity.

  11. Intrinsic Topological Insulator Bi1.5Sb0.5Te3-xSex Thin Crystals

    PubMed Central

    Wang, Wei; Li, Li; Zou, Wenqin; He, Liang; Song, Fengqi; Zhang, Rong; Wu, Xiaoshan; Zhang, Fengming

    2015-01-01

    The quaternary topological insulator (Bi,Sb)2(Te,Se)3 has demonstrated topological surface states with an insulating bulk. Scientists have identified an optimized composition of Bi1.5Sb0.5Te1.7Se1.3 with the highest resistivity reported. But the physics that drive to this composition remains unclear. Here we report the crystal structure and the magneto-transport properties of Bi1.5Sb0.5Te3-xSex (BSTS) series. A correlation between the structure and the physical properties has been revealed. We found out that within the rhombohedral structure, the composition with most Te substituting Se has the highest resistivity. On the other hand, segregation of other composition phases will introduce much higher bulk concentration. PMID:25604579

  12. Optical Probing of Ultrafast Electronic Decay in Bi and Sb with Slow Phonons

    NASA Astrophysics Data System (ADS)

    Li, J. J.; Chen, J.; Reis, D. A.; Fahy, S.; Merlin, R.

    2013-01-01

    Illumination with laser sources leads to the creation of excited electronic states of particular symmetries, which can drive isosymmetric vibrations. Here, we use a combination of ultrafast stimulated and cw spontaneous Raman scattering to determine the lifetime of A1g and Eg electronic coherences in Bi and Sb. Our results both shed new light on the mechanisms of coherent phonon generation and represent a novel way to probe extremely fast electron decoherence rates. The Eg state, resulting from an unequal distribution of carriers in three equivalent band regions, is extremely short lived. Consistent with theory, the lifetime of its associated driving force reaches values as small as 2 (6) fs for Bi (Sb) at 300 K.

  13. Liquidus of Silicon Binary Systems

    NASA Astrophysics Data System (ADS)

    Safarian, Jafar; Kolbeinsen, Leiv; Tangstad, Merete

    2011-08-01

    Thermodynamic knowledge about liquid silicon is crucial for the production of solar-grade silicon feedstock from molten silicon. In the current study, liquidus for silicon binary alloys is formulated using a previously developed method in which the liquidus curve is calculated using two constants. The liquidus measurements for the silicon portion of the silicon alloys with Al, Ca, Mg, Fe, Ti, Zn, Cu, Ag, Au, Pt, Sn, Pb, Bi, Sb, Ga, In, Ni, Pd, Mn, and Rh are reviewed, and the consistent data were used to determine the liquidus constants. The liquidus curves for silicon binary systems are calculated and plotted. It is indicated that the calculated liquidus curves fit well with the experimental data. A correlation between the determined liquidus constants is also observed, which can be used to gain a better understanding of the thermodynamics of the silicon binary melts.

  14. Hot Wall Epitaxy And Characterization Of Bismuth And Antimony Thin Films On Barium Fluoride Substrates

    NASA Astrophysics Data System (ADS)

    Collazo, Ramon; Dalmau, Rafael; Martinez, Antonio

    1998-03-01

    We have grown thin films of bismuth and antimony using hot wall epitaxy. The epitaxial films were grown on (111)-BaF2 substrates. The chemical integrity of the films was established using Auger electron spectroscopy and X ray Photoelectron Spectroscopy. The thickness of the films was measured using an atomic force microscope to establish their growth rate. The crystallographic properties of the films were assessed using x-ray diffraction techniques. Both bismuth and antimony thin films were found to be oriented with the [003] direction perpendicular to the plane of the films. Pole figures of both types of films indicate the epitaxial nature of the films. Bi/Sb multilayer structures were grown using the same growth technique. We will report on the results of the characterization of these films as well as on the growth apparatus and process. Work supported in part by EPSCoR-NSF Grant EHR-9108775 and NCRADA-NSWCDD-92-01.

  15. Determination of tungsten with iron(III) after reduction with mercury in thiocyanate medium.

    PubMed

    Yatirajam, V; Dhamija, S

    1976-01-01

    Tungsten(V) is formed by shaking for 2 min sodium tungstate solution in 0.4 M potassium thiocyanate-4M hydrochloric acid medium, with mercury. It is titrated with standard iron(III) solution. The thiocyanate present stabilizes W(V) to aerial oxidation and also acts as indicator. The W(V) can also be titrated potentiometrically in 7M hydrochloric acid, a tungsten wire electrode being used. Fe, Ni, Cr, Zr, Bi, Sb, Ce, Al, Pb, Ca and U do not interfere. Cu, V and As can be tolerated up to 5 mg. Co, Mo, Re, Nb and Mn interfere, but not in the potentiometric determination. The method is direct, simple, rapid, accurate and reproducible. PMID:18961802

  16. Thermoelectric microdevice fabricated by a MEMS-like electrochemical process

    NASA Technical Reports Server (NTRS)

    Snyder, G. Jeffrey; Lim, James R.; Huang, Chen-Kuo; Fleurial, Jean-Pierre

    2003-01-01

    Microelectromechanical systems (MEMS) are the basis of many rapidly growing technologies, because they combine miniature sensors and actuators with communications and electronics at low cost. Commercial MEMS fabrication processes are limited to silicon-based materials or two-dimensional structures. Here we show an inexpensive, electrochemical technique to build MEMS-like structures that contain several different metals and semiconductors with three-dimensional bridging structures. We demonstrate this technique by building a working microthermoelectric device. Using repeated exposure and development of multiple photoresist layers, several different metals and thermoelectric materials are fabricated in a three-dimensional structure. A device containing 126 n-type and p-type (Bi, Sb)2Te3 thermoelectric elements, 20 microm tall and 60 microm in diameter with bridging metal interconnects, was fabricated and cooling demonstrated. Such a device should be of technological importance for precise thermal control when operating as a cooler, and for portable power when operating as a micro power generator.

  17. Magnetic Coupling in FeBi2Se4 and FeSb2Se4 from first principles

    NASA Astrophysics Data System (ADS)

    Williams, Logan; Kioupakis, Emmanouil; Lopez, Juan; Poudeu, Pierre Ferdinand P.

    Spintronic devices offer benefits in power efficiency and size reduction over current electronics, but require the development of semiconductor materials with favorable magnetic properties. Specifically, a high ferromagnetic-to-paramagnetic Curie transition temperature is required for spintronics operation at room temperature. FeBi2Se4 and FeSb2Se4 are two n and p-type magnetic semiconductors, respectively, with Curie transition temperatures of 450K. We employ first-principles calculations based on density functional theory to examine the magnetic coupling mechanisms in these materials. Our results indicate that antisite defects of Fe upon the Bi/Sb sites are crucial to the ferromagnetic coupling of the Fe magnetic moments in the crystals. This research was supported by the National Science Foundation CAREER award through Grant No. DMR-1254314. Computational Resources were provided by the DOE NERSC facility.

  18. Experimental realization of quantized anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Xue, Qi-Kun

    2014-03-01

    Anomalous Hall effect was discovered by Edwin Hall in 1880. In this talk, we report the experimental observation of the quantized version of AHE, the quantum anomalous Hall effect (QAHE) in thin films of Cr-doped (Bi,Sb)2Te3 magnetic topological insulator. At zero magnetic field, the gate-tuned anomalous Hall resistance exhibits a quantized value of h /e2 accompanied by a significant drop of the longitudinal resistance. The longitudinal resistance vanishes under a strong magnetic field whereas the Hall resistance remains at the quantized value. The realization of QAHE paves a way for developing low-power-consumption electronics. Implications on observing Majorana fermions and other exotic phenomena in magnetic topological insulators will also be discussed. The work was collaborated with Ke He, Yayu Wang, Xucun Ma, Xi Chen, Li Lv, Dai Xi, Zhong Fang and Shoucheng Zhang.

  19. Thickness dependent band gap of Bi2-xSbxTe3 (x = 0, 0.05, 0.1) thin films

    NASA Astrophysics Data System (ADS)

    Patel, M. M.; Soni, P. H.; Desai, C. F.

    2016-05-01

    Thin films of Bi2Te3(Sb) were prepared on alkali halide crystal substrates. Sb content and the film thickness were varied. Bi2Te3 is a narrow gap semiconductor. Bi-Sb is a continuous solid solution of substitutional type and Sb therefore was used to test its effect on the band gap. The film thickness variation was also taken up. The infra-red absorption spectra were used in the wave number range 400 cm-1 to 4000 cm-1. The band gap obtained from the absorption data was found to increase with decreasing thickness since the thickness range used was from 30 nm to 170 nm. This is a range corresponding to nanostructures and hence quantum size effect was observed as expected. The band gap also exhibited Sb content dependence. The detail results are have been reported and explained.

  20. Fabrication of Thermoelectric Devices by Applying Microsystems Technology

    NASA Astrophysics Data System (ADS)

    Goncalves, L. M.; Alpuim, P.; Correia, J. H.

    2010-09-01

    Microsystems technologies were applied in the fabrication of thermoelectric (TE) microconverters. Common techniques used in microelectromechanical systems (MEMS) fabrication, namely wet etching, lift-off (with SU-8 photoresist), reactive ion etching (RIE), and lithography-electroplating-molding, were compared in the fabrication process of TE microsystems based on Bi, Sb, and Te thin-film compounds. Thin films of bismuth and antimony tellurides were deposited by co-evaporation, with figures of merit comparable to those of bulk materials. Test structures were fabricated using lithography and wet etching. The etching recipe was optimized by varying the etchant dilution and composition until higher etch rates and desired material selectivity were attained. Since the etching process is applied after deposition, this process allows prior deposition of TE materials by any deposition method; thus, films with high figure of merit can be fabricated. Moreover, wet etching does not require the use of expensive equipment.

  1. Cyclotene diaphragm for MEMS based IR detectors

    NASA Astrophysics Data System (ADS)

    Guo, Shuwen

    2003-01-01

    A novel structure employing Dow Chemical (Midland, MI) benzocyclobutene (BCB) Cyclotene as a diaphragm material is presented in this report. The main advantages of this BCB diaphragm are its low thermal conductivity, robustness, chemical inertness, low curing temperature and high structure yield. Moreover, a BCB film can be either photo-defined or plasma etched and is a suitable micromachining material for post IC processing. Micromachined IR thermopile single detectors and lineal detector arrays (1×16), using BiSeTeSb/BiSbTe sensing elements on BCB diaphragms, have been constructed and tested. Up to 100% structure yield has been obtained. The process used to realize this detector structure is compatible with the eventual inclusion of on-chip circuitry for signal amplification and conditioning.

  2. Investigating dissipation in the quantum anomalous Hall effect

    NASA Astrophysics Data System (ADS)

    Fox, Eli; Bestwick, Andrew; Goldhaber-Gordon, David; Feng, Yang; Ou, Yunbo; He, Ke; Wang, Yayu; Xue, Qi-Kun; Kou, Xufeng; Pan, Lei; Wang, Kang

    In the quantum anomalous Hall effect, a magnetic exchange gap in a 3D topological insulator gives rise to dissipationless chiral edge states. Though the effect has recently been realized in a family of ferromagnetically-doped (Bi,Sb)2Te3 topological insulator thin films, experiments to date have found non-vanishing longitudinal resistance, contrary to initial theoretical expectations. Proposed sources of this dissipation include extra gapless or activated quasi-helical edge states, thermally activated 2D conduction, and variable-range hopping. Here, we discuss transport measurements of Corbino disk and non-local geometries to identify the mechanism of non-ideal behavior. This work supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. 19-7503.

  3. Effects of B-site chemistry on BiFeO[subscript 3]-containing enhanced tetragonality systems

    SciTech Connect

    Stein, David M.; Davies, Peter K.

    2012-02-06

    The ternary perovskite systems PbTiO{sub 3}-BiFeO{sub 3}-Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3} and PbTiO{sub 3}-BiFeO{sub 3}-BiScO{sub 3} were investigated to clarify the relationship between the observance of multiple dielectric transitions and B-site chemistry. Multiple dielectric transitions were observed for a range of compositions in the Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-containing system. A temperature-dependent diffraction study confirmed the existence of a cubic and tetragonal co-existence region at temperatures between the two transitions. No similar dielectric behavior was observed in the PbTiO{sub 3}-BiFeO{sub 3}-BiScO{sub 3} system.

  4. The simultaneous enhancement of photorefraction and optical damage resistance in MgO and Bi2O3 co-doped LiNbO3 crystals.

    PubMed

    Zheng, Dahuai; Kong, Yongfa; Liu, Shiguo; Chen, Muling; Chen, Shaolin; Zhang, Ling; Rupp, Romano; Xu, Jingjun

    2016-01-01

    For a long time that optical damage was renamed as photorefraction, here we find that the optical damage resistance and photorefraction can be simultaneously enhanced in MgO and Bi2O3 co-doped LiNbO3 (LN:Bi,Mg). The photorefractive response time of LN:Bi,Mg was shortened to 170 ms while the photorefractive sensitivity reached up to 21 cm(2)/J. Meanwhile, LN:Bi,Mg crystals could withstand a light intensity higher than 10(6)  W/cm(2) without apparent optical damage. Our experimental results indicate that photorefraction doesn't equal to optical damage. The underground mechanism was analyzed and attributed to that diffusion dominates the transport process of charge carriers, that is to say photorefraction causes only slight optical damage under diffusion mechanism, which is very important for the practical applications of photorefractive crystals, such as in holographic storage, integrated optics and 3D display. PMID:26837261

  5. The simultaneous enhancement of photorefraction and optical damage resistance in MgO and Bi2O3 co-doped LiNbO3 crystals

    PubMed Central

    Zheng, Dahuai; Kong, Yongfa; Liu, Shiguo; Chen, Muling; Chen, Shaolin; Zhang, Ling; Rupp, Romano; Xu, Jingjun

    2016-01-01

    For a long time that optical damage was renamed as photorefraction, here we find that the optical damage resistance and photorefraction can be simultaneously enhanced in MgO and Bi2O3 co-doped LiNbO3 (LN:Bi,Mg). The photorefractive response time of LN:Bi,Mg was shortened to 170 ms while the photorefractive sensitivity reached up to 21 cm2/J. Meanwhile, LN:Bi,Mg crystals could withstand a light intensity higher than 106  W/cm2 without apparent optical damage. Our experimental results indicate that photorefraction doesn’t equal to optical damage. The underground mechanism was analyzed and attributed to that diffusion dominates the transport process of charge carriers, that is to say photorefraction causes only slight optical damage under diffusion mechanism, which is very important for the practical applications of photorefractive crystals, such as in holographic storage, integrated optics and 3D display. PMID:26837261

  6. Metallurgy, thermal stability, and failure mode of the commercial Bi-Te-based thermoelectric modules.

    SciTech Connect

    Yang, Nancy Y. C.; Morales, Alfredo Martin

    2009-02-01

    Bi-Te-based thermoelectric (TE) alloys are excellent candidates for power generation modules. We are interested in reliable TE modules for long-term use at or below 200 C. It is known that the metallurgical characteristics of TE materials and of interconnect components affect the performance of TE modules. Thus, we have conducted an extensive scientific investigation of several commercial TE modules to determine whether they meet our technical requirements. Our main focus is on the metallurgy and thermal stability of (Bi,Sb){sup 2}(Te,Se){sup 3} TE compounds and of other materials used in TE modules in the temperature range between 25 C and 200 C. Our study confirms the material suite used in the construction of TE modules. The module consists of three major components: AlN cover plates; electrical interconnects; and the TE legs, P-doped (Bi{sub 8}Sb{sub 32})(Te{sub 60}) and N-doped (Bi{sub 37}Sb{sub 3})(Te{sub 56}Se{sub 4}). The interconnect assembly contains Sn (Sb {approx} 1wt%) solder, sandwiched between Cu conductor with Ni diffusion barriers on the outside. Potential failure modes of the TE modules in this temperature range were discovered and analyzed. The results show that the metallurgical characteristics of the alloys used in the P and N legs are stable up to 200 C. However, whole TE modules are thermally unstable at temperatures above 160 C, lower than the nominal melting point of the solder suggested by the manufacture. Two failure modes were observed when they were heated above 160 C: solder melting and flowing out of the interconnect assembly; and solder reacting with the TE leg, causing dimensional swelling of the TE legs. The reaction of the solder with the TE leg occurs as the lack of a nickel diffusion barrier on the side of the TE leg where the displaced solder and/or the preexisting solder beads is directly contact the TE material. This study concludes that the present TE modules are not suitable for long-term use at temperatures above 160 C due

  7. An experimental study on the geochemical behavior of highly siderophile elements (HSE) and metalloids (As, Se, Sb, Te, Bi) in a mss-iss-pyrite system at 650 °C: A possible magmatic origin for Co-HSE-bearing pyrite and the role of metalloid-rich phases in the fractionation of HSE

    NASA Astrophysics Data System (ADS)

    Cafagna, Fabio; Jugo, Pedro J.

    2016-04-01

    Pyrite, the most abundant sulfide in the Earth's crust, is an accessory mineral in several magmatic sulfide deposits. Although most pyrite is hydrothermal, previous experimental studies have shown that pyrite can also have a primary magmatic origin, by exsolving from monosulfide solid solution (mss) during cooling of a sulfide melt, if sulfur fugacity is sufficiently high. Pyrite from some localities has significant amounts of Co, and complex zonation in some low-melting-point chalcophile elements (LMCE), such as As, Se, Sb, Te, Bi (henceforth referred to as metalloids) and some platinum-group elements (PGE: Ru, Rh, Pd, Os, Ir, Pt). However, the origin of such pyrite and the causes of zonation are not clear. Because the distribution of some of these elements is heterogeneous and seems to be developed in concentric zones, the zonation has been interpreted to represent growth stages, some of them secondary and caused partly by hydrothermal fluids. Better constraints on the origin of Co-PGE-bearing pyrite could help unravel the geochemical processes affecting the sulfide assemblages in which it is found; thus, an experimental study was undertaken to characterize pyrite formation in magmatic sulfide environments and its relationship with metalloids and highly siderophile elements (HSE: PGE, Re, Au). Natural pyrrhotite, chalcopyrite, pentlandite and elemental S were mixed and doped with approximately 50 ppm of each HSE. A mixture of metalloids was added at 0.2 wt.% or 3 wt.% to aliquots of sulfide mixtures. Starting materials were sealed in evacuated silica tubes and fused at 1200 °C. The temperature was subsequently reduced to 750 °C (at 60 °C/h), then to 650 °C (at 0.5 °C/h) to produce relatively large euhedral pyrite crystals, then quenched. The experiments were analyzed using reflected light, SEM, EPMA and LA-ICP-MS. Experimental products contained euhedral pyrite, mss, intermediate solid solution (iss) and metalloid-rich phases, interpreted as quench product of an immiscible metalloid-rich liquid. The results show that Co-Ni-HSE-bearing pyrite with complex zonation in Ru, Rh, Os, Ir, and Pt can form by a subsolidus reaction involving both mss and iss, and does not require secondary (e.g. hydrothermal) processes. Because such pyrite results from the cooling of a sulfide melt (after mss and iss) it can be described as magmatic. Among the HSE, Ru, Rh, Os, Re and Ir have identical zonation patterns in pyrite, Pt is also zoned but differently, and Au and Pd are essentially excluded. Previously documented natural HSE-bearing pyrite also display identical zonation patterns in Ru, Rh, Os and Ir. The complex zoning is likely preserved due to the extremely slow diffusion rates for those elements in pyrite. Thus, the presence of pyrite with similar characteristic in natural sulfide assemblages is consistent with a magmatic origin and does not require hydrothermal processes. The results also show that if a metalloid-rich liquid is present it will significantly sequester Au, Pd and Pt, but will not affect Ru, Rh, Os, Re and Ir. In the absence of metalloid-rich phases, Au partitions strongly into iss and Pd partitions preferentially into mss.

  8. Observation of topological surface state quantum Hall effect in an intrinsic three-dimensional topological insulator

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong; Yong P. Chen's Group in Purdue Team; Chih-Kang Shih's Group in UT-Austin Collaboration; M. Zahid Hasan's Group in Princeton Collaboration

    2015-03-01

    A three-dimensional (3D) topological insulator (TI) is a novel quantum matter with a gapped insulating bulk yet a conducting surface hosting topologically-protected gapless surface states of Dirac fermions. One of the most distinct electronic transport signatures predicted for such topological surface states (TSS) is a half-integer quantum Hall effect (QHE) in a magnetic field. We have observed well-developed QHE arising from TSS in an intrinsic TI of BiSbTeSe2. Our samples can exhibit surface dominated conduction even close to room temperature, while the bulk conduction is negligible. At low temperatures and high perpendicular magnetic fields, the Hall conductance shows well quantized integer plateaux in exfoliated flake devices on SiO2 / Si substrates, where the top and bottom surface each contributing a half integer e2 / h Hall conductance, accompanied by vanishing longitudinal resistance. We have also studied dual-gated devices where both the top and bottom surfaces can be independently gated. Such intrinsic 3D TI materials exhibiting no measurable bulk conduction and well-developed surface state QHE pave the way for further applications of topological quantum electronics. DARPA MESO program (Grant N66001-11-1-4107).

  9. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators

    DOE PAGESBeta

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P.

    2016-05-04

    Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at the doublemore » Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. As a result, such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation.« less

  10. Incommensurate host-guest structures in compressed elements: Hume—Rothery effects as origin

    NASA Astrophysics Data System (ADS)

    Degtyareva, V. F.

    2015-11-01

    Discovery of the incommensurate structure in the element Ba under pressure 15 years ago was followed by findings of a series of similar structures in other compressed elements. Incommensurately modulated structures of the host-guest type consist of a tetragonal host structure and a guest structure. The guest structure forms chains of atoms embedded in the channels of host atoms so that the axial ratio of these subcells along the c axis is not rational. Two types of the host-guest structures have been found so far: with the host cells containing 8 atoms and 16 atoms; in these both types the guest cells contain 2 atoms. These crystal structures contain a non-integer number of atoms in their unit cell: tI11* in Bi, Sb, As, Ba, Sr, Sc and tI19* in Na, K, Rb. We consider here a close structural relationship of these host-guest structures with the binary alloy phase Au3Cd5-tI32. This phase is related to the family of the Hume-Rothery phases that is stabilized by the Fermi sphere-Brillouin zone interaction. From similar considerations for alkali and alkaline-earth elements a necessary condition for structural stability emerges in which the valence electrons band overlaps with the upper core electrons and the valence electron count increases under compression.

  11. Crystallinity of tellurium capping and epitaxy of ferromagnetic topological insulator films on SrTiO3

    PubMed Central

    Park, Jihwey; Soh, Yeong-Ah; Aeppli, Gabriel; Feng, Xiao; Ou, Yunbo; He, Ke; Xue, Qi-Kun

    2015-01-01

    Thin films of topological insulators are often capped with an insulating layer since topological insulators are known to be fragile to degradation. However, capping can hinder the observation of novel transport properties of the surface states. To understand the influence of capping on the surface states, it is crucial to understand the crystal structure and the atomic arrangement at the interfaces. Here, we use x-ray diffraction to establish the crystal structure of magnetic topological insulator Cr-doped (Bi,Sb)2Te3 (CBST) films grown on SrTiO3 (1 1 1) substrates with and without a Te capping layer. We find that both the film and capping layer are single crystal and that the crystal quality of the film is independent of the presence of the capping layer, but that x-rays cause sublimation of the CBST film, which is prevented by the capping layer. Our findings show that the different transport properties of capped films cannot be attributed to a lower crystal quality but to a more subtle effect such as a different electronic structure at the interface with the capping layer. Our results on the crystal structure and atomic arrangements of the topological heterostructure will enable modelling the electronic structure and design of topological heterostructures. PMID:26123202

  12. Scalable Silicon Nanostructuring for Thermoelectric Applications

    NASA Astrophysics Data System (ADS)

    Koukharenko, E.; Boden, S. A.; Platzek, D.; Bagnall, D. M.; White, N. M.

    2013-07-01

    The current limitations of commercially available thermoelectric (TE) generators include their incompatibility with human body applications due to the toxicity of commonly used alloys and possible future shortage of raw materials (Bi-Sb-Te and Se). In this respect, exploiting silicon as an environmentally friendly candidate for thermoelectric applications is a promising alternative since it is an abundant, ecofriendly semiconductor for which there already exists an infrastructure for low-cost and high-yield processing. Contrary to the existing approaches, where n/ p-legs were either heavily doped to an optimal carrier concentration of 1019 cm-3 or morphologically modified by increasing their roughness, in this work improved thermoelectric performance was achieved in smooth silicon nanostructures with low doping concentration (1.5 × 1015 cm-3). Scalable, highly reproducible e-beam lithographies, which are compatible with nanoimprint and followed by deep reactive-ion etching (DRIE), were employed to produce arrays of regularly spaced nanopillars of 400 nm height with diameters varying from 140 nm to 300 nm. A potential Seebeck microprobe (PSM) was used to measure the Seebeck coefficients of such nanostructures. This resulted in values ranging from -75 μV/K to -120 μV/K for n-type and 100 μV/K to 140 μV/K for p-type, which are significant improvements over previously reported data.

  13. Quantum transport in topological insulator nanoribbon field effect and Josephson devices

    NASA Astrophysics Data System (ADS)

    Kayyalha, Morteza; Jauregui, Luis; Kazakov, Aleksander; Pettes, Michael; Miotkowski, Ireneusz; Shi, Li; Rokhinson, Leonid; Chen, Yong

    The spin-helical topological surface states (TSS) of topological insulators have attracted great attention in the past few years as an excellent platform to study topological transport and other exotic physics such as Majorana fermions. Here we present experiments studying quantum transport of TSS in topological insulator nanoribbon (TINR) field effect devices with normal as well as superconducting contacts. In Bi2Te3 NRs with normal contacts, we observe that the conductance vs. axial magnetic field exhibits Aharonov-Bohm (AB) oscillations with an alternating phase of zero and π, depending periodically on the Fermi momentum kF tuned by an applied back-gate voltage, consistent with the 1D sub-band structure formed by circumferentially quantized TSS. We also investigated the Josephson effects in BiSbTeSe2 TINRs with superconducting Nb contacts. We measured the gate voltage and temperature dependence of the supercurrent and multiple Andreev reflections (MAR), to probe phase coherent transport via TSS

  14. Development of a Measurement System for the Figure of Merit in the High-Temperature Region

    NASA Astrophysics Data System (ADS)

    Iwasaki, H.; Yamamoto, T.; Kim, H.; Nakamoto, G.

    2013-07-01

    New equipment has been developed for evaluating the figure of merit, ZT, on the basis of the Harman method in the temperature range between room temperature and 650 K. In this temperature range, the sample holder in the vacuum chamber has a different construction as compared with the sample holder constructed for the temperature range below room temperature. Several issues that need to be considered, such as compensation for the thermal radiation effect, suppression of heat leakage from the lead wires, and the setup method for the lead wires on the sample, are examined in the considered temperature region. Evaluations of ZT are successfully made for typical thermoelectric materials, (Bi,Sb)2Te3 and CeFe3CoSb12. We then demonstrate that the influence of thermal radiation between the high- and low-temperature edges of the sample induced by the Peltier effect on the estimated value of ZT is negligible at around 600 K. Furthermore, the change in the thermoelectric properties due to repetition of the thermal cycle is studied, and a typical hysteresis behavior is observed in the considered thermoelectric materials. It is revealed that heating the sample to a high temperature causes a change in its thermoelectric properties, which one must take into account for practical applications of thermoelectric materials.

  15. Role of trivalent antimony in the removal of As, Sb, and Bi impurities from copper electrolytes

    NASA Astrophysics Data System (ADS)

    Xiao, Fa-xin; Cao, Dao; Mao, Jian-wei; Shen, Xiao-ni; Ren, Feng-zhang

    2013-01-01

    The role of trivalent antimony was investigated in removing As, Sb, and Bi impurities from a copper electrolyte. Purification experiments were carried out by adding a various concentrations of Sb(III) ions in a synthetic electrolyte containing 185 g/L sulfuric acid, 45 g/L Cu2+, 10 g/L As, and 0.5 g/L Bi under stirring at 65°C for 2 h. The electrolyte was filtered, and the structure, morphology and composition of the precipitate were analyzed by means of chemical analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and IR spectroscopy. The precipitate is composed of irregular lumps which are agglomerated by fine dendritic and floccus particles, and it mainly consists of As, Sb, Bi, and O elements. Characteristic bands in the IR spectra of the precipitate are As-OX (X=As, Sb, Bi), Sb-OY (Y=Sb, Bi), O-As-O, As-OH, Sb-OH, and O-H. The precipitate is a mixture of microcrystalline SbAsO4, (Sb,As)2O3, and amorphous phases. As, Sb, and Bi impurities are effectively removed from the copper electrolyte by Sb(III) ions attributing to these precipitates.

  16. Modelling of segmented high-performance thermoelectric generators with effects of thermal radiation, electrical and thermal contact resistances

    NASA Astrophysics Data System (ADS)

    Ouyang, Zhongliang; Li, Dawen

    2016-04-01

    In this study, segmented thermoelectric generators (TEGs) have been simulated with various state-of-the-art TE materials spanning a wide temperature range, from 300 K up to 1000 K. The results reveal that by combining the current best p-type TE materials, BiSbTe, MgAgSb, K-doped PbTeS and SnSe with the strongest n-type TE materials, Cu-Doped BiTeSe, AgPbSbTe and SiGe to build segmented legs, TE modules could achieve efficiencies of up to 17.0% and 20.9% at ΔT = 500 K and ΔT = 700 K, respectively, and a high output power densities of over 2.1 Watt cm‑2 at the temperature difference of 700 K. Moreover, we demonstrate that successful segmentation requires a smooth change of compatibility factor s from one end of the TEG leg to the other, even if s values of two ends differ by more than a factor of 2. The influence of the thermal radiation, electrical and thermal contact effects have also been studied. Although considered potentially detrimental to the TEG performance, these effects, if well-regulated, do not prevent segmentation of the current best TE materials from being a prospective way to construct high performance TEGs with greatly enhanced efficiency and output power density.

  17. Thermoelectric microdevice fabricated by a MEMS-like electrochemical process.

    PubMed

    Snyder, G Jeffrey; Lim, James R; Huang, Chen-Kuo; Fleurial, Jean-Pierre

    2003-08-01

    Microelectromechanical systems (MEMS) are the basis of many rapidly growing technologies, because they combine miniature sensors and actuators with communications and electronics at low cost. Commercial MEMS fabrication processes are limited to silicon-based materials or two-dimensional structures. Here we show an inexpensive, electrochemical technique to build MEMS-like structures that contain several different metals and semiconductors with three-dimensional bridging structures. We demonstrate this technique by building a working microthermoelectric device. Using repeated exposure and development of multiple photoresist layers, several different metals and thermoelectric materials are fabricated in a three-dimensional structure. A device containing 126 n-type and p-type (Bi, Sb)2Te3 thermoelectric elements, 20 microm tall and 60 microm in diameter with bridging metal interconnects, was fabricated and cooling demonstrated. Such a device should be of technological importance for precise thermal control when operating as a cooler, and for portable power when operating as a micro power generator. PMID:12883550

  18. Visualization of superparamagnetic dynamics in magnetic topological insulators.

    PubMed

    Lachman, Ella O; Young, Andrea F; Richardella, Anthony; Cuppens, Jo; Naren, H R; Anahory, Yonathan; Meltzer, Alexander Y; Kandala, Abhinav; Kempinger, Susan; Myasoedov, Yuri; Huber, Martin E; Samarth, Nitin; Zeldov, Eli

    2015-11-01

    Quantized Hall conductance is a generic feature of two-dimensional electronic systems with broken time reversal symmetry. In the quantum anomalous Hall state recently discovered in magnetic topological insulators, time reversal symmetry is believed to be broken by long-range ferromagnetic order, with quantized resistance observed even at zero external magnetic field. We use scanning nanoSQUID (nano-superconducting quantum interference device) magnetic imaging to provide a direct visualization of the dynamics of the quantum phase transition between the two anomalous Hall plateaus in a Cr-doped (Bi,Sb)2Te3 thin film. Contrary to naive expectations based on macroscopic magnetometry, our measurements reveal a superparamagnetic state formed by weakly interacting magnetic domains with a characteristic size of a few tens of nanometers. The magnetic phase transition occurs through random reversals of these local moments, which drive the electronic Hall plateau transition. Surprisingly, we find that the electronic system can, in turn, drive the dynamics of the magnetic system, revealing a subtle interplay between the two coupled quantum phase transitions. PMID:26601138

  19. Visualization of superparamagnetic dynamics in magnetic topological insulators

    PubMed Central

    Lachman, Ella O.; Young, Andrea F.; Richardella, Anthony; Cuppens, Jo; Naren, H. R.; Anahory, Yonathan; Meltzer, Alexander Y.; Kandala, Abhinav; Kempinger, Susan; Myasoedov, Yuri; Huber, Martin E.; Samarth, Nitin; Zeldov, Eli

    2015-01-01

    Quantized Hall conductance is a generic feature of two-dimensional electronic systems with broken time reversal symmetry. In the quantum anomalous Hall state recently discovered in magnetic topological insulators, time reversal symmetry is believed to be broken by long-range ferromagnetic order, with quantized resistance observed even at zero external magnetic field. We use scanning nanoSQUID (nano–superconducting quantum interference device) magnetic imaging to provide a direct visualization of the dynamics of the quantum phase transition between the two anomalous Hall plateaus in a Cr-doped (Bi,Sb)2Te3 thin film. Contrary to naive expectations based on macroscopic magnetometry, our measurements reveal a superparamagnetic state formed by weakly interacting magnetic domains with a characteristic size of a few tens of nanometers. The magnetic phase transition occurs through random reversals of these local moments, which drive the electronic Hall plateau transition. Surprisingly, we find that the electronic system can, in turn, drive the dynamics of the magnetic system, revealing a subtle interplay between the two coupled quantum phase transitions. PMID:26601138

  20. Modelling of segmented high-performance thermoelectric generators with effects of thermal radiation, electrical and thermal contact resistances

    PubMed Central

    Ouyang, Zhongliang; Li, Dawen

    2016-01-01

    In this study, segmented thermoelectric generators (TEGs) have been simulated with various state-of-the-art TE materials spanning a wide temperature range, from 300 K up to 1000 K. The results reveal that by combining the current best p-type TE materials, BiSbTe, MgAgSb, K-doped PbTeS and SnSe with the strongest n-type TE materials, Cu-Doped BiTeSe, AgPbSbTe and SiGe to build segmented legs, TE modules could achieve efficiencies of up to 17.0% and 20.9% at ΔT = 500 K and ΔT = 700 K, respectively, and a high output power densities of over 2.1 Watt cm−2 at the temperature difference of 700 K. Moreover, we demonstrate that successful segmentation requires a smooth change of compatibility factor s from one end of the TEG leg to the other, even if s values of two ends differ by more than a factor of 2. The influence of the thermal radiation, electrical and thermal contact effects have also been studied. Although considered potentially detrimental to the TEG performance, these effects, if well-regulated, do not prevent segmentation of the current best TE materials from being a prospective way to construct high performance TEGs with greatly enhanced efficiency and output power density. PMID:27052592

  1. High-mobility surface states and conductance fluctuations in Bismuth Telluro-Sulfide topological insulator devices

    NASA Astrophysics Data System (ADS)

    Trivedi, Tanuj; Sonde, Sushant; Movva, Hema C. P.; Banerjee, Sanjay K.

    Since the experimental discovery of three-dimensional topological insulators (TI), (Bi,Sb)2(Se,Te)3 binary compounds are the principal material systems to explore TI physics. However, transport experiments studying surface-states are complicated by parallel bulk conductivity contribution, which is expected to improve for ternary and quaternary chalcogenide compounds of Bi and Sb. A promising alternative is the Sulfur-based tetradymite with an ideal formula of Bi2Te2S, which has received little attention. We present van der Waals epitaxial growth and magnetotransport in Bismuth Telluro-Sulfide (BTS) crystalline nanosheets. Gating-enhanced Weak-antilocalization (WAL) and Universal Conductance Fluctuations (UCF) are observed in BTS devices. Empirical modeling of the data shows the existence of two-dimensional surface transport. A three-channel Hall conductivity model is proposed, which is utilized in conjunction with an extended-WAL analysis, showing the presence of a high-mobility surface component and indication for separation of transport channels in BTS devices. Our growth and comprehensive transport experiments demonstrate BTS as a promising candidate TI material.

  2. Controlled improvement in specific contact resistivity for thermoelectric materials by ion implantation

    NASA Astrophysics Data System (ADS)

    Taylor, Patrick J.; Maddux, Jay R.; Meissner, Greg; Venkatasubramanian, Rama; Bulman, Gary; Pierce, Jonathan; Gupta, Rahul; Bierschenk, Jim; Caylor, Chris; D'Angelo, Jonathan; Ren, Zhifeng

    2013-07-01

    To obtain reduced specific contact resistivity, iodine donors and silver acceptors were ion-implanted into n-type and p-type (Bi,Sb)2(Se,Te)3 materials, respectively, to achieve >10 times higher doping at the surface. Implantation into n-type materials caused the specific contact resistivity to decrease from 1.7 × 10-6 Ω cm2 to 4.5 × 10-7 Ω cm2. Implantation into p-type materials caused specific contact resistivity to decrease from 7.7 × 10-7 Ω cm2 to 2.7 × 10-7 Ω cm2. For implanted thin-film superlattices, the non-implanted values of 1.4 × 10-7 Ω cm2 and 5.3 × 10-8 Ω cm2 precipitously dropped below the detection limit after implantation, ≤10-8 Ω cm2. These reductions in specific contact resistivity are consistent with an increase in tunneling across the contact.

  3. Factors of the accumulation of heavy metals and metalloids at geochemical barriers in urban soils

    NASA Astrophysics Data System (ADS)

    Kosheleva, N. E.; Kasimov, N. S.; Vlasov, D. V.

    2015-05-01

    The bulk contents and concentrations of mobile (extracted by an ammonium acetate buffer with EDTA) Cd, Pb, Sb, As, Bi, Zn, and Cu were determined in the surface horizons of urban soils in the Eastern administrative okrug of Moscow. The regression analysis showed that the accumulation of these metals and metalloids in the soils is controlled by the physicochemical soil properties and by number of anthropogenic factors and landscape conditions (geochemical position, type of loose deposits, character of land use, dust load, vehicle emissions, building pattern, percent of green areas, and the extent of sealed soils). The precipitation of studied elements on the geochemical barriers had the following regularities: Cd, Cu, and Zn accumulated on the alkaline barriers; Bi, Sb, As, Cu, Pb, and Zn, on chemisorption barriers; Sb, As, and Pb, on organomineral barriers; and Cd and Cu, on the sorption-sedimentation barriers. Technogenic transformation of the physicochemical properties of urban soils resulted in the increase of the mean bulk contents of heavy metals and metalloids by 33-99%; the portion of elements fixed on the geochemical barriers increased by 26-50%.

  4. Observation of Pairing Correlations in Strongly Localized Amorphous Films

    NASA Astrophysics Data System (ADS)

    Stewart, M. D., Jr.; Valles, J. M., Jr.; Yin, Aijun; Xu, J. M.

    2007-03-01

    We have measured the Superconductor to Insulator Transition (SIT) as a function of thickness at dilution refrigerator temperatures in ultrathin Bi/Sb films perforated with a regular honeycomb array of holes separated by 100 nm. The presence of these perforations profoundly influences the character of the transition. In particular, on the insulating side of the SIT, the resistance as a function of temperature, R(T), rises monotonically and becomes activated below 1K. Closer to the SIT, a minimum develops in the R(T) suggestive of strong superconducting fluctuations and the onset of Cooper pairing. Simultaneously, the perpendicular field magnetoresistance begins to oscillate with a period that corresponds to the superconducting flux quantum. Yet thicker films exhibit a relatively broad R(T) transition toward a zero resistance state. This behavior constitutes direct evidence that the superconducting ground state of this amorphous film system emerges from an insulating state containing localized Cooper pairs. This work has been supported by the NSF through DMR-0203608, and DMR-0605797, AFRL, and ONR.

  5. Chern half metals: a new class of topological materials to realize the quantum anomalous Hall effect.

    PubMed

    Hu, Jun; Zhu, Zhenyue; Wu, Ruqian

    2015-03-11

    New topological insulators that demonstrate the quantum anomalous Hall effect (QAHE) are a cutting-edge research topic in condensed matter physics and materials science. So far, the QAHE has been observed only in Cr-doped (Bi,Sb)2Te3 at extremely low temperature. Therefore, it is important to find new materials with large topological band gap and high thermal stability for the realization of the QAHE. On the basis of first-principles and tight-binding model calculations, we discovered a new class of topological phase, Chern half metal, which manifests the QAHE in one spin channel while is metallic in the other spin channel, in Co or Rh deposited graphene. The QAHE is robust in these sytems for the adatom coverage ranging from 2% to 6%. Meanwhile, these systems have large perpendicular magnetic anisotropy energies of 5.3 and 11.5 meV, necessary for the observation of the QAHE at reasonably high temperature. PMID:25689149

  6. Enhanced thermoelectric performance of Cu2Se/Bi0.4Sb1.6Te3 nanocomposites at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Li, Y. Y.; Qin, X. Y.; Li, D.; Zhang, J.; Li, C.; Liu, Y. F.; Song, C. J.; Xin, H. X.; Guo, H. F.

    2016-02-01

    Bi2Te3-based thermoelectric materials with large thermoelectric figure of merit, ZT, at elevated temperatures are advantageous in power generation by using the low-grade waste heat. Here, we show that incorporation of small proportion (0.3 vol. %) of nanophase Cu2Se into BiSbTe matrix causes an enhanced high-temperature thermopower due to elevated energy filtering of carriers and inhibition of minority transport besides enhanced phonon blocking from scattering at interfaces, which concurrently result in an ˜20% increase in the power factor and an ˜60% reduction in the lattice thermal conductivity at 488 K. As a result, ZT = 1.6 is achieved at 488 K in the composite system with 0.3 vol. % of Cu2Se. Significantly, its ZT is larger than unit in broad high-temperature range (e.g., ZT = 1.3 at 400 K and ZT = 1.6 at 488 K), which makes this material to be attractive for applications in energy harvesting from the low-grade waste heat.

  7. Structural and proximity-induced ferromagnetic properties of topological insulator-magnetic insulator heterostructures

    NASA Astrophysics Data System (ADS)

    Jiang, Zilong; Chang, Cui-Zu; Tang, Chi; Zheng, Jian-Guo; Moodera, Jagadeesh S.; Shi, Jing

    2016-05-01

    The spontaneously broken time reversal symmetry can lead to the formation of an energy gap in the Dirac spectrum of the surface states of a topological insulator (TI) which can consequently give rise to a variety of interesting phenomena potentially useful for spintronics. In this work, we couple a non-magnetic TI to a high Curie temperature TC magnetic insulator to induce strong exchange interaction via the proximity effect. We have successfully grown 5 quintuple layer thick ternary TI (BixSb1-x)2Te3 films on atomically flat yttrium iron garnet (YIG) film with the combination of molecular beam epitaxy and pulsed laser deposition, in which the Fermi level position relative to the Dirac point is varied by controlling the Bi:Sb ratio. The anomalous Hall effect (AHE) and suppressed weak antilocalization (WAL) measured under out of plane magnetic fields reveal that the TI surface in contact with YIG is magnetized. Our high-quality (BixSb1-x)2Te3/Y IG heterostructure provides a tunable system for exploring the quantum anomalous Hall effect (QAHE) at higher temperatures in TI-based spintronic devices.

  8. Optical Control of Ferromagnetism in a Magnetically-Doped Topological Insulator

    NASA Astrophysics Data System (ADS)

    Yeats, Andrew L.; Mintun, Peter J.; Pan, Yu; Richardella, Anthony; Samarth, Nitin; Awschalom, David D.

    Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate micron-scale optical control of both magnetization and chemical potential in thin films of Cr-doped (Bi,Sb)2Te3. By optically modulating the coercivity of the films, we write and erase arbitrary spatial configurations of their magnetization, which we then image with Kerr microscopy. Additionally, by optically manipulating a space charge layer in the underlying SrTiO3 substrates, we can control the local chemical potential of the films. This allows us to write and erase p- n junctions in the films, which we image with photocurrent microscopy. Both effects persist for > 16 hours. We will present systematic Kerr microscopy, photocurrent microscopy, and electrical transport studies of these materials and various electronic and magnetic structures patterned on them. We will discuss the prospects for using these optical phenomena to study and control the unique physics of TIs, such as edge-state transport in the quantum anomalous Hall regime. This work is supported by ONR, AFOSR-MURI, ARO, and NSF.

  9. Crystallinity of tellurium capping and epitaxy of ferromagnetic topological insulator films on SrTiO3.

    PubMed

    Park, Jihwey; Soh, Yeong-Ah; Aeppli, Gabriel; Feng, Xiao; Ou, Yunbo; He, Ke; Xue, Qi-Kun

    2015-01-01

    Thin films of topological insulators are often capped with an insulating layer since topological insulators are known to be fragile to degradation. However, capping can hinder the observation of novel transport properties of the surface states. To understand the influence of capping on the surface states, it is crucial to understand the crystal structure and the atomic arrangement at the interfaces. Here, we use x-ray diffraction to establish the crystal structure of magnetic topological insulator Cr-doped (Bi,Sb)2Te3 (CBST) films grown on SrTiO3 (1 1 1) substrates with and without a Te capping layer. We find that both the film and capping layer are single crystal and that the crystal quality of the film is independent of the presence of the capping layer, but that x-rays cause sublimation of the CBST film, which is prevented by the capping layer. Our findings show that the different transport properties of capped films cannot be attributed to a lower crystal quality but to a more subtle effect such as a different electronic structure at the interface with the capping layer. Our results on the crystal structure and atomic arrangements of the topological heterostructure will enable modelling the electronic structure and design of topological heterostructures. PMID:26123202

  10. Quantum anomalous Hall effect in time-reversal-symmetry breaking topological insulators.

    PubMed

    Chang, Cui-Zu; Li, Mingda

    2016-03-31

    The quantum anomalous Hall effect (QAHE), the last member of Hall family, was predicted to exhibit quantized Hall conductivity σ(yx) = e2/h without any external magnetic field. The QAHE shares a similar physical phenomenon with the integer quantum Hall effect (QHE), whereas its physical origin relies on the intrinsic topological inverted band structure and ferromagnetism. Since the QAHE does not require external energy input in the form of magnetic field, it is believed that this effect has unique potential for applications in future electronic devices with low-power consumption. More recently, the QAHE has been experimentally observed in thin films of the time-reversal symmetry breaking ferromagnetic (FM) topological insulators (TI), Cr- and V- doped (Bi,Sb)2Te3. In this topical review, we review the history of TI based QAHE, the route to the experimental observation of the QAHE in the above two systems, the current status of the research of the QAHE, and finally the prospects for future studies. PMID:26934535

  11. Computational study of Met-Car analogue heterofullerenes

    NASA Astrophysics Data System (ADS)

    Domingos, H. S.

    2006-06-01

    Structural, chemical and electronic properties of a number of Met-Car analogue heterofullerenes were investigated using a combination of ab initio and semi-empirical quantum mechanical calculations.Met-Car clusters of known structure and chemistry were studied together with some new hypothetical configurations. In particular, the stability of clusters of the form Y8C12 (Y = Al, S, Si, Ti, As, Bi, Sb, P, N, B, Sn, Sc, Cr, V), XY7C12 (X, Y = B, N, Si) and Y8Z12 (Y, Z = N, B, Si) were investigated based on computed binding energies, Mulliken charges, bond orders and ionization potentials. The results indicate that some novel clusters are due for observation. Clusters of this type are known to form the building blocks of new polymerized solids and may exhibit some novel dielectric, magnetic and superconducting properties. Isomers of D3d symmetry, which are possible global energy minima for Cr, V and Sc carbide clusters, were also identified.

  12. Quantum anomalous Hall effect in time-reversal-symmetry breaking topological insulators

    NASA Astrophysics Data System (ADS)

    Chang, Cui-Zu; Li, Mingda

    2016-03-01

    The quantum anomalous Hall effect (QAHE), the last member of Hall family, was predicted to exhibit quantized Hall conductivity {σyx}=\\frac{{{e}2}}{h} without any external magnetic field. The QAHE shares a similar physical phenomenon with the integer quantum Hall effect (QHE), whereas its physical origin relies on the intrinsic topological inverted band structure and ferromagnetism. Since the QAHE does not require external energy input in the form of magnetic field, it is believed that this effect has unique potential for applications in future electronic devices with low-power consumption. More recently, the QAHE has been experimentally observed in thin films of the time-reversal symmetry breaking ferromagnetic (FM) topological insulators (TI), Cr- and V- doped (Bi,Sb)2Te3. In this topical review, we review the history of TI based QAHE, the route to the experimental observation of the QAHE in the above two systems, the current status of the research of the QAHE, and finally the prospects for future studies.

  13. Persistent optical gating of a topological insulator

    PubMed Central

    Yeats, Andrew L.; Pan, Yu; Richardella, Anthony; Mintun, Peter J.; Samarth, Nitin; Awschalom, David D.

    2015-01-01

    The spin-polarized surface states of topological insulators (TIs) are attractive for applications in spintronics and quantum computing. A central challenge with these materials is to reliably tune the chemical potential of their electrons with respect to the Dirac point and the bulk bands. We demonstrate persistent, bidirectional optical control of the chemical potential of (Bi,Sb)2Te3 thin films grown on SrTiO3. By optically modulating a space-charge layer in the SrTiO3 substrates, we induce a persistent field effect in the TI films comparable to electrostatic gating techniques but without additional materials or processing. This enables us to optically pattern arbitrarily shaped p- and n-type regions in a TI, which we subsequently image with scanning photocurrent microscopy. The ability to optically write and erase mesoscopic electronic structures in a TI may aid in the investigation of the unique properties of the topological insulating phase. The gating effect also generalizes to other thin-film materials, suggesting that these phenomena could provide optical control of chemical potential in a wide range of ultrathin electronic systems. PMID:26601300

  14. Magnetic-Field Dependence of Thermoelectric Properties of Sintered Bi90Sb10 Alloy

    NASA Astrophysics Data System (ADS)

    Murata, Masayuki; Yamamoto, Atsushi; Hasegawa, Yasuhiro; Komine, Takashi

    2016-03-01

    The magnetic-field dependence of the thermoelectric properties and dimensionless figure of merit ( ZT) of a sintered Bi90Sb10 alloy were experimentally and theoretically evaluated. The Bi-Sb alloy was synthesized in a quartz ampule using the melting method, and the resultant ingot was then ground via ball milling. A sintered Bi90Sb10 alloy with a particle size in the range of several to several tens of micrometers was prepared using the spark plasma sintering (SPS) method. The magnetic-field dependence of the electrical resistivity, Seebeck coefficient, and thermal conductivity were experimentally evaluated at temperatures of 77-300 K for magnetic fields of up to 2.9 T. The results showed that ZT increased by 37% at 300 K under a 2.5-T magnetic field. A theoretical calculation of the magneto-Seebeck coefficient based on the Boltzmann equation with a relaxation time approximation was also performed. Hence, the experimental result for the magneto-Seebeck coefficient of the Bi90Sb10 alloy at 300 K was qualitatively and quantitatively explained. Specifically, the carrier scattering mechanism was shown to be acoustic phonon potential scattering and the carrier mobility ratio between the L- and T-points was found to be 3.3, which corresponds to the characteristics of a single crystal. It was concluded that the effect of the magnetic field on the Seebeck coefficient was demonstrated accurately using the theoretical calculation model.

  15. Ion exchange defines the biological activity of titanate nanotubes.

    PubMed

    Rónavári, Andrea; Kovács, Dávid; Vágvölgyi, Csaba; Kónya, Zoltán; Kiricsi, Mónika; Pfeiffer, Ilona

    2016-05-01

    One-dimensional titanate nanotubes (TiONTs) were subjected to systematic ion exchange to determine the impact of these modifications on biological activities. Ion exchanged TiONTs (with Ag, Mg, Bi, Sb, Ca, K, Sr, Fe, and Cu ions) were successfully synthesized and the presence of the substituted ions was verified by energy dispersive X-ray spectroscopy (EDS). A complex screening was carried out to reveal differences in toxicity to human cells, as well as in antibacterial, antifungal, and antiviral activities between the various modified nanotubes. Our results demonstrated that Ag ion exchanged TiONTs exerted potent antibacterial and antifungal effects against all examined microbial species but were ineffective on viruses. Surprisingly, the antibacterial activity of Cu/TiONTs was restricted to Micrococcus luteus. Most ion exchanged TiONTs did not show antimicrobial activity against the tested bacterial and fungal species. Incorporation of various ions into nanotube architectures lead to mild, moderate, or even to a massive loss of human cell viability; therefore, this type of biological effect exerted by TiONTs can be greatly modulated by ion exchange. These findings further emphasize the contribution of ion exchange in determining not only the physical and chemical characteristics but also the bioactivity of TiONT against different types of living cells. PMID:26972521

  16. Memristive Switching in Bi(1-x)Sb(x) Nanowires.

    PubMed

    Han, Nalae; Park, Myung Uk; Yoo, Kyung-Hwa

    2016-04-13

    We investigated the memristive switching behavior in bismuth-antimony alloy (Bi(1-x)Sb(x)) single nanowire devices at 0.1 ≤ x ≤ 0.42. At 0.15 ≤ x ≤ 0.42, most Bi(1-x)Sb(x) single nanowire devices exhibited bipolar resistive switching (RS) behavior with on/off ratios of approximately 10(4) and narrow variations in switching parameters. Moreover, the resistance values in the low-resistance state (LRS) were insensitive to x. On the other hand, at 0.1 ≤ x ≤ 0.15, some Bi(1-x)Sb(x) single nanowire devices showed complementary RS-like behavior, which was ascribed to asymmetric contact properties. Transmission electron microscopy and elemental mapping images of Bi, Sb, and O obtained from the cross sections of the Bi(1-x)Sb(x) single nanowire devices, which were cut before and after RS, revealed that the mobile species was Sb ions, and the migration of the Sb ions to the nanowire surface brought the switch to LRS. In addition, we demonstrated that two types of synaptic plasticity, namely, short-term plasticity and long-term potentiation, could be implemented in Bi(1-x)Sb(x) nanowires by applying a sequence of voltage pulses with different repetition intervals. PMID:27042861

  17. Optimizing Spin Generation in 2D Materials: Topological Insulators and Graphene

    NASA Astrophysics Data System (ADS)

    Chen, Ching-Tzu

    Novel two-dimensional electronic systems with Dirac-like dispersion present unique opportunities for spintronic applications. In this seminar I will discuss two specific examples. First we examine the potential of topological insulators as spin-source materials. Using a new spin-polarized tunneling method, giant charge-spin conversion efficiency in topological insulators is revealed, well exceeding that in conventional magnetic tunnel junctions. Through a comparative study between Bi2Se3 and (Bi,Sb)2Te3, we verify the topological-surface-state origin of the observed giant spin signals and further extract the energy dependence of the effective spin polarization in Bi2Se3. Next we explore the potential of interfacial exchange interaction in 2D materials for spin control and spin generation. Using graphene as a prototype, we demonstrate that its coupling to a model magnetic insulator (EuS) produces a substantial magnetic exchange field (>14 T), which yields orders-of-magnitude enhancement in the spin signal originated from the Zeeman spin-Hall effect. Furthermore, the strong exchange field lifts the spin degeneracy of graphene in the quantum Hall regime, which may lead to interesting spin-polarized edge transport and thus open up new application space for classical and quantum information processing.

  18. Optimizing Thermoelectric Properties in Composites

    NASA Astrophysics Data System (ADS)

    Adams, Michael J.; Jin, Hyungyu; Heremans, Joseph P.

    Here we consider semiconductor composites as a way to yield high thermoelectric figure of merit. Effective medium theory limits the figure of merit of a composite made from two non-interacting materials, A and B, to the larger of the two. In previous work, we describe a mechanism that can lift this limitation by treating charge and heat flux separately. Silica beads coated with a conducting shell are inserted into a thermoelectric host. Thermal conductivity decreases with insulating material added, but electrical conductivity is maintained via locally conducting surfaces. We apply the theory to p-type (Bi,Sb)2Te3 host material. Several permutations are possible: Te-coated beads in Sb-rich material, or Sb-coated beads in Te-rich material. First, we review data for varying bead coatings and heat treatments, followed by varying stoichiometry in the host. New data considers an additional parameter of varying bead diameter, as well as optimizing these parameters simultaneously to enhance thermoelectric performance.

  19. Semiconductors for thermoelectric and spin-thermal solid-state energy conversion

    NASA Astrophysics Data System (ADS)

    Heremans, Joseph P.

    2013-03-01

    The recent decade has seen a doubling of the efficiency of thermoelectric converters through the use of nanotechnology. Here we first outline how specific doping impurities in semiconductors, called resonant levels, mimic the effects of nanostructures and give the same benefits in bulk semiconductors. Resonant impurities catalyse the formation of new bands in semiconductors, which can be engineered to tailor the thermopower. The result is an efficiency increase of 50% in BiSb and more in PbTe. Then, we describe a new solid-state heat-to-electricity conversion mechanism, the spin-Seebeck effect, which arises from driving spinpolarized particles out of thermal equilibrium. This generates a spin flux that is converted into a voltage in a non-polarized adjacent material; the effect can be as large as the highest thermoelectric voltages in semiconductors. Nanotechnologies and these new effects add new design variables to the old problem of optimizing the thermoelectric figure of merit, resulting in much improved thermal efficiencies.

  20. Thermoelectric power factor performance of Bi85Sb15/graphene composite

    NASA Astrophysics Data System (ADS)

    El-Asfoury, Mohamed S.; Nasr, Mohamed N. A.; Nakamura, Koichi; Abdel-Moneim, Ahmed

    2016-04-01

    Composite materials based on Bi85Sb15 with commercial graphene (Gr) nanoparticles have been synthesized by mechanical alloying and hot isostatic pressing. The effect of different amount of Gr nanoparticles (x = 0.02, 0.04, 0.06, and 0.08 wt %) on the thermoelectric properties of (Bi85Sb15)1- x Gr x composite was investigated. X-ray diffraction and scanning electron microscopy were carried out for the structure characterization of the composites. Transport properties, including electrical resistivity, Seebeck coefficient, and calculated power factor, were investigated and their variations were discussed with regard to microstructures in the temperature range of 173-373 K. Resistivity significantly declines in the sample with x = 0.04 wt % Gr, and the enhancement was 7% at 230 K and reached about 7.6% at room temperature. With 0.08 wt % Gr, a high absolute value of the Seebeck coefficient was observed. The power factor reaches its maximum of 3.7 × 10-3 W·m-1·K-2 with x = 0.08 wt % at 173 K. The results reflect that this synthesis process can be a powerful method of obtaining homogeneous Bi-Sb thermoelectric composite materials rapidly and at low cost. In addition, the demand for uniform coherent composites was significant because of their high-performance transport properties.

  1. Magnetic Cr doping of Bi2Se3: Evidence for divalent Cr from x-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Figueroa, A. I.; van der Laan, G.; Collins-McIntyre, L. J.; Zhang, S.-L.; Baker, A. A.; Harrison, S. E.; Schönherr, P.; Cibin, G.; Hesjedal, T.

    2014-10-01

    Ferromagnetically doped topological insulators with broken time-reversal symmetry are a prerequisite for observing the quantum anomalous Hall effect. Cr-doped (Bi,Sb)2(Se,Te)3 is the most successful materials system so far, as it combines ferromagnetic ordering with acceptable levels of additional bulk doping. Here, we report a study of the local electronic structure of Cr dopants in epitaxially grown Bi2Se3 thin films. Contrary to the established view that the Cr dopant is trivalent because it substitutionally replaces Bi3+, we find instead that Cr is divalent. This is evidenced by the energy positions of the Cr K and L2,3 absorption edges relative to reference samples. The extended x-ray absorption fine structure at the K edge shows that the Cr dopants substitute on octahedral sites with the surrounding Se ions contracted by Δd =-0.36 Å, in agreement with recent band structure calculations. Comparison of the Cr L2,3 x-ray magnetic circular dichroism at T =5 K with multiplet calculations gives a spin moment of 3.64 μB/Crbulk, which is close to the saturation moment for Cr2+ d4. The reduced Cr oxidation state in doped Bi2Se3 is ascribed to the formation of a covalent bond between Cr d (eg) and Se p orbitals, which is favored by the contraction of the Cr-Se distances.

  2. Electrical Probing of Inherent Spin Polarization in a Topological Insulator with Electrical Gating

    NASA Astrophysics Data System (ADS)

    Lee, Joon Sue; Richardella, Anthony; Samarth, Nitin

    2015-03-01

    The hallmark of a time-reversal symmetry protected three-dimensional topological insulator is the helically spin-textured surface state. Although electrical detection of spin polarization in topological insulators has been demonstrated very recently, there have not been any electrical measurements to demonstrate the entire mapping of the spin polarization throughout the surface state. We report the electrical probing of the spin-polarized surface state using a magnetic tunnel junction as a spin detector while the chemical potential of a topological insulator (Bi,Sb)2Te3 is tuned by back gating. Hysteretic spin signals were observed as the magnetization of the detector ferromagnet (permalloy) switches with in-plane magnetic field. Changing the direction of bias current through the topological insulator channel flips the direction of the spin polarization, resulting in the reverse of sign of the detected spin signals. We demonstrate the control of the Fermi energy, which has importance not only in further understanding of the spin-momentum locking in the surface state but also in possible electrical tuning of the spin polarization for potential spin-based devices. Supported by C-SPIN & DARPA/SRC.

  3. Duo gating on a 3D topological insulator - independent tuning of both topological surface states

    NASA Astrophysics Data System (ADS)

    Li, Chuan; de Ronde, Bob; Snelder, Marieke; Stehno, Martin; Huang, Yingkai; Golden, Mark; Brinkman, Alexander; ICE Team; IOP Collaboration

    ABSTRACT: Topological insulators are associated with a trove of exciting physics, such as the ability to host robust anyons, Majorana Bound States, which can be used for quantum computation. For future Majorana devices it is desirable to have the Fermi energy tuned as close as possible to the Dirac point of the topological surface state. Based on previous work on gating BSTS, we report the experimental progress towards gate-tuning of the top and bottom topological surface states of BiSbTeSe2 crystal flakes. When the Fermi level is moved across the Dirac point conduction is shown to change from electron dominated transport to hole dominated transport independently for either surface. In the high magnetic field, one can tune the system precisely between the different landau levels of both surfaces, thus a full gating map of the possible landau levels combination is established. In addition, we provide a simple capacitance model to explain the general hysteresis behaviors in topological insulator systems.

  4. Nanotubes from Misfit Layered Compounds: A New Family of Materials with Low Dimensionality.

    PubMed

    Panchakarla, Leela S; Radovsky, Gal; Houben, Lothar; Popovitz-Biro, Ronit; Dunin-Borkowski, Rafal E; Tenne, Reshef

    2014-11-01

    Nanotubes that are formed from layered materials have emerged to be exciting one-dimensional materials in the last two decades due to their remarkable structures and properties. Misfit layered compounds (MLC) can be produced from alternating assemblies of two different molecular slabs with different periodicities with the general formula [(MX)1+x]m[TX2]n (or more simply MS-TS2), where M is Sn, Pb, Bi, Sb, rare earths, T is Sn, Nb, Ta, Ti, V, Cr, and so on, and X is S, Se. The presence of misfit stresses between adjacent layers in MLC provides a driving force for curling of the layers that acts in addition to the elimination of dangling bonds. The combination of these two independent forces leads to the synthesis of misfit layered nanotubes, which are newcomers to the broad field of one-dimensional nanostructures and nanotubes. The synthesis, characterization, and microscopic details of misfit layered nanotubes are discussed, and directions for future research are presented. PMID:26278742

  5. Visualization of superparamagnetic dynamics in magnetic topological insulators

    NASA Astrophysics Data System (ADS)

    Lachman, E.; Young, A. F.; Richardella, A.; Cuppens, J.; Hr, N.; Anahory, Y.; Meltzer, A. Y.; Kandala, A.; Kempinger, S.; Myasoedov, Y.; Huber, M. E.; Samarth, N.; Zeldov, E.

    Magnetically doped topological insulators have recently been shown to host a quantum anomalous Hall (QAH) state at low temperatures. Using scanning nanoSQUID magnetic imaging on a Cr-doped (Bi , Sb) 2 Te3 thin film[1], we reveal that the magnetic structure of magnetically doped topological insulators is not ferromagnetic as assumed so far. In fact it is superparamagnetic, formed by weakly interacting magnetic domains. These domains have a characteristic size of a few tens of nanometers, and undergo random reversals which drive the electronic state from one Hall plateau to the other. The superparamagnetic state is metastable, with small energy barriers to relaxation. We observe magnetic relaxation even at 300 mK, evident also in transport measurements. Unexpectedly, magnetic relaxation can also be induced by varying the gate voltage, and we propose a mechanism for the influence of the electronic phase on the magnetic relaxation. We speculate that the dynamic nature of magnetic disorder in QAH systems may contribute to the observed fragility of the QAH state at elevated temperatures.

  6. Crystallinity of tellurium capping and epitaxy of ferromagnetic topological insulator films on SrTiO3

    NASA Astrophysics Data System (ADS)

    Park, Jihwey; Soh, Yeong-Ah; Aeppli, Gabriel; Feng, Xiao; Ou, Yunbo; He, Ke; Xue, Qi-Kun

    2015-06-01

    Thin films of topological insulators are often capped with an insulating layer since topological insulators are known to be fragile to degradation. However, capping can hinder the observation of novel transport properties of the surface states. To understand the influence of capping on the surface states, it is crucial to understand the crystal structure and the atomic arrangement at the interfaces. Here, we use x-ray diffraction to establish the crystal structure of magnetic topological insulator Cr-doped (Bi,Sb)2Te3 (CBST) films grown on SrTiO3 (1 1 1) substrates with and without a Te capping layer. We find that both the film and capping layer are single crystal and that the crystal quality of the film is independent of the presence of the capping layer, but that x-rays cause sublimation of the CBST film, which is prevented by the capping layer. Our findings show that the different transport properties of capped films cannot be attributed to a lower crystal quality but to a more subtle effect such as a different electronic structure at the interface with the capping layer. Our results on the crystal structure and atomic arrangements of the topological heterostructure will enable modelling the electronic structure and design of topological heterostructures.

  7. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P.

    Topological insulators (TI) are a novel class of quantum matter with a gapped insulating bulk yet gapless spin helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film TI devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully-tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity of 4e2 / h at the double Dirac point, a series of ambipolar two-component ''half-integer'' Dirac quantum Hall states and an electron-hole total filling factor ν=0 state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction respectively. Such a system paves the way to explore rich physics ranging from topological magnetoelectric effects to exciton condensation. DARPA MESO program.

  8. Manipulating edge transport in quantum anomalous Hall insulators

    NASA Astrophysics Data System (ADS)

    Kandala, Abhinav

    The quantum anomalous Hall (QAH) effect provides a path to obtain dissipation-less, one-dimensional (1D) edge states at zero magnetic field. It's recent experimental realization in magnetic topological insulator thin films lies at the overlap of several areas of condensed matter physics: dilute magnetic semiconductors, low dimensional electron transport and topologically non-trivial material systems. In this talk, we demonstrate how careful compositional and electrical tuning of epitaxial films of Cr-doped (Bi,Sb)2Te3 enables access to a robust zero-field quantized Hall effect, despite sample roughness and low carrier mobility. In samples that show near-dissipation-less transport, we manipulate the intermixing between edge states and dissipative channels via a tilted-field crossover from ballistic 1D edge transport to diffusive transport. This crossover manifests in a gate-tunable giant anisotropic magneto-resistance effect that we use as a quantitative probe of dissipation in our systems. Finally, we discuss experiments with mesoscopic channels of QAH insulator thin films, and discuss the effect of their modified magnetic anisotropy on edge transport. This work was carried out in collaboration with A. Richardella, C-X Liu, M. Liu, W. Wang, N. P. Ong, and N. Samarth. Funded by ARO/MURI, DARPA and ONR.

  9. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators.

    PubMed

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P

    2016-01-01

    Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at the double Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. Such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation. PMID:27142344

  10. Interdiffusion studies in Bi-based layered systems with nanosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Missana, T.; Afonso, C. N.; da Silva, M. F.

    1994-12-01

    Interdiffusion processes are induced by nanosecond laser pulses from an excimer laser. The Bi-based systems studied are formed by a Bi layer and a Sb or Ge layer. Configurations with Bi at the surface layer or at the innermost layer are both studied. Real-time reflectivity measurements are performed during the irradiation to determine the process kinetics and times and Rutherford backscattering spectrometry is used to obtain the concentration depth profiles. It will be shown that there is an interfacially initiated diffusion process in the Bi-Sb system and that the diffusion coefficients of this system within the liquid phase are in the 10-5 10-6 cm2/s range. The Bi-Ge system shows instead little mixing, the diffusion coefficients of the system within the liquid phase being at least two orders of magnitude lower. The differences observed when Bi is the surface layer or the innermost one are related to the different thermal responses of the system.

  11. Quantum transport of two-species Dirac fermions in dual-gated three-dimensional topological insulators

    PubMed Central

    Xu, Yang; Miotkowski, Ireneusz; Chen, Yong P.

    2016-01-01

    Topological insulators are a novel class of quantum matter with a gapped insulating bulk, yet gapless spin-helical Dirac fermion conducting surface states. Here, we report local and non-local electrical and magneto transport measurements in dual-gated BiSbTeSe2 thin film topological insulator devices, with conduction dominated by the spatially separated top and bottom surfaces, each hosting a single species of Dirac fermions with independent gate control over the carrier type and density. We observe many intriguing quantum transport phenomena in such a fully tunable two-species topological Dirac gas, including a zero-magnetic-field minimum conductivity close to twice the conductance quantum at the double Dirac point, a series of ambipolar two-component half-integer Dirac quantum Hall states and an electron-hole total filling factor zero state (with a zero-Hall plateau), exhibiting dissipationless (chiral) and dissipative (non-chiral) edge conduction, respectively. Such a system paves the way to explore rich physics, ranging from topological magnetoelectric effects to exciton condensation. PMID:27142344

  12. Field induced gap infrared detector

    NASA Technical Reports Server (NTRS)

    Elliott, C. Thomas (Inventor)

    1990-01-01

    A tunable infrared detector which employs a vanishing band gap semimetal material provided with an induced band gap by a magnetic field to allow intrinsic semiconductor type infrared detection capabilities is disclosed. The semimetal material may thus operate as a semiconductor type detector with a wavelength sensitivity corresponding to the induced band gap in a preferred embodiment of a diode structure. Preferred semimetal materials include Hg(1-x)Cd(x)Te, x is less than 0.15, HgCdSe, BiSb, alpha-Sn, HgMgTe, HgMnTe, HgZnTe, HgMnSe, HgMgSe, and HgZnSe. The magnetic field induces a band gap in the semimetal material proportional to the strength of the magnetic field allowing tunable detection cutoff wavelengths. For an applied magnetic field from 5 to 10 tesla, the wavelength detection cutoff will be in the range of 20 to 50 micrometers for Hg(1-x)Cd(x)Te alloys with x about 0.15. A similar approach may also be employed to generate infrared energy in a desired band gap and then operating the structure in a light emitting diode or semiconductor laser type of configuration.

  13. Surface-Micromachined Planar Arrays of Thermopiles

    NASA Technical Reports Server (NTRS)

    Foote, Marc C.

    2003-01-01

    Planar two-dimensional arrays of thermopiles intended for use as thermal-imaging detectors are to be fabricated by a process that includes surface micromachining. These thermopile arrays are designed to perform better than do prior two-dimensional thermopile arrays. The lower performance of prior two-dimensional thermopile arrays is attributed to the following causes: The thermopiles are made from low-performance thermoelectric materials. The devices contain dielectric supporting structures, the thermal conductances of which give rise to parasitic losses of heat from detectors to substrates. The bulk-micromachining processes sometimes used to remove substrate material under the pixels, making it difficult to incorporate low-noise readout electronic circuitry. The thermoelectric lines are on the same level as the infrared absorbers, thereby reducing fill factor. The improved pixel design of a thermopile array of the type under development is expected to afford enhanced performance by virtue of the following combination of features: Surface-micromachined detectors are thermally isolated through suspension above readout circuitry. The thermopiles are made of such high-performance thermoelectric materials as Bi-Te and Bi-Sb-Te alloys. Pixel structures are supported only by the thermoelectric materials: there are no supporting dielectric structures that could leak heat by conduction to the substrate.

  14. Transport studies of mesoscopic and magnetic topological insulators

    NASA Astrophysics Data System (ADS)

    Kandala, Abhinav

    integration of GdN with Bi2Se 3 thin films. Careful structural, magnetic and electrical characterization of the heterostructures is employed to confirm that the magnetic species is solely restricted to the surface, and that the ferromagnetic GdN layer to be insulating, ensuring current flow solely through the TI layer. We also devise a novel device geometry that enables direct comparison of the magneto-transport properties of TI films with and without proximate magnetism, all, in a single device. A comparative study of weak anti-localization suggested that the overlying GdN suppressed quantum interference in the top surface state. In our second generation heterostructure devices, GdN is interfaced with low-carrier density, gate-tunable thin films of (Bi,Sb)2Te3 grown on SrTiO 3 substrates. These devices enable us to map out the comparison of magneto-transport, as the chemical potential is tuned from the bulk conduction band into the bulk valence band. In a second approach to study the effects of magnetism on TI's, I shall present, in Chapter 5, our results from magnetic doping of (Bi,Sb) 2Te3 thin films with Cr -- a system that was recently demonstrated to be a Quantum Anomalous Hall (QAH) insulator. In a Cr-rich regime, a highly insulating, high Curie temperature ferromagnetic phase is achieved. However, a careful, iterative process of tuning the composition of this complex alloy enabled access to the QAHE regime, with the observation of near dissipation-less transport and perfect Hall quantization at zero external field. Furthermore, we demonstrate a field tilt driven crossover between a quantum anomalous Hall phase and a gapless, ferromagnetic TI phase. This crossover manifests itself in an electrically tunable, giant anisotropic magneto-resistance effect that we employ as a quantitative probe of edge transport in this system.

  15. Geology, petrography, geochemistry, and genesis of sulfide-rich pods in the Lac des Iles palladium deposits, western Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Duran, Charley J.; Barnes, Sarah-Jane; Corkery, John T.

    2016-04-01

    The Lac des Iles Pd deposits are known for their Pd-rich sulfide-poor mineralization. However, previously undocumented sulfide-rich pods also occur within the intrusion that hosts the deposits. Given the complex magmatic and hydrothermal history of the mineralization at Lac des Iles, the sulfide-rich pods could have crystallized from magmatic sulfide liquids or precipitated from hydrothermal fluids. Sulfide-rich pods occur throughout the stratigraphy, in all rock types, and along comagmatic shear zones, and contain net-textured to massive sulfides. They can be divided into four main groups based on the variation in mineral assemblages: (1) pyrrhotite-pentlandite ± pyrite-chalcopyrite-magnetite-ilmenite; (2) chalcopyrite ± pyrrhotite-pentlandite-pyrite-magnetite-ilmenite; (3) pyrite ± pentlandite-chalcopyrite-pyrrhotite-magnetite-ilmenite; and (4) magnetite ± ilmenite-pyrrhotite-pentlandite-pyrite-chalcopyrite. Whole rock metal contents and S isotopic compositions do not change with the amount of pyrite present, except for slight enrichments in As and Bi. The presence of an essentially magmatic sulfide mineral assemblage (pyrrhotite-pentlandite ± chalcopyrite) with pentlandite exsolution flames in pyrrhotite in some pods suggests that the pods crystallized from magmatic sulfide liquids. The very low Cu contents of the pods suggests that they are mainly cumulates of monosulfide solid solution (MSS). We propose a model whereby sulfide liquids were concentrated into dilation zones prior to crystallizing cumulus MSS. Intermediate solid solution crystallized from the fractionated liquids at the edges of some pods leaving residual liquids enriched in Pt, Pd, Au, As, Bi, Sb, and Te. These residual liquids are no longer associated with the pods. During subsequent alteration, pyrite replaced MSS/pyrrhotite, but this did not affect the platinum-group element contents of the pods.

  16. Environmental assessment of the arsenic-rich, Rodalquilar gold-(copper-lead-zinc) mining district, SE Spain: data from soils and vegetation

    NASA Astrophysics Data System (ADS)

    Oyarzun, Roberto; Cubas, Paloma; Higueras, Pablo; Lillo, Javier; Llanos, Willians

    2009-08-01

    The Rodalquilar mineral deposits (SE Spain) were formed in Miocene time in relation to caldera volcanic episodes and dome emplacement phenomena. Two types of ore deposits are recognized: (1) the El Cinto epithermal, Au-As high sulphidation vein and breccia type; and (2) peripheral low sulphidation epithermal Pb-Zn-Cu-(Au) veins. The first metallurgical plants for gold extraction were set up in the 1920s and used amalgamation. Cyanide leaching began in the 1930s and the operations lasted until the mid 1960s. The latter left a huge pile of ~900,000-1,250,000 m3 of abandoned As-rich tailings adjacent to the town of Rodalquilar. A frustrated initiative to reactivate the El Cinto mines took place in the late 1980s and left a heap leaching pile of ~120,000 m3. Adverse mineralogical and structural conditions favoured metal and metalloid dispersion from the ore bodies into soils and sediments, whereas mining and metallurgical operations considerably aggravated contamination. We present geochemical data for soils, tailings and wild plant species. Compared to world and local baselines, both the tailings and soils of Rodalquilar are highly enriched in As (mean concentrations of 950 and 180 μg g-1, respectively). Regarding plants, only the concentrations of As, Bi and Sb in Asparagus horridus, Launaea arborescens, Salsola genistoides, and Stipa tenacissima are above the local baselines. Bioaccumulation factors in these species are generally lower in the tailings, which may be related to an exclusion strategy for metal tolerance. The statistical analysis of geochemical data from soils and plants allows recognition of two well-differentiated clusters of elements (As-Bi-Sb-Se-Sn-Te and Cd-Cu-Hg-Pb-Zn), which ultimately reflect the strong chemical influence of both El Cinto and peripheral deposits mineral assemblages.

  17. New Interest in Intermetallic Compound ZnSb

    NASA Astrophysics Data System (ADS)

    Fedorov, M. I.; Prokof'eva, L. V.; Pshenay-Severin, D. A.; Shabaldin, A. A.; Konstantinov, P. P.

    2014-06-01

    The intermetallic compound ZnSb has been known since the 1830s. It has semiconductor properties, but its mechanical, thermal, and chemical properties are very close to those of a metallic alloy. When thermoelectrics based on (BiSb)2(TeSe)3 solid solutions were created, interest in ZnSb subsided. However, the current situation is different, as tellurium has become expensive and rare. Moreover, its compounds are too toxic, and it is too difficult to produce such materials and devices from these solid solutions. Recently, n-type material based on Mg2(SnSi) solid solution was proposed in the Laboratory of Physics for Thermoelements of the Ioffe Physical-Technical Institute. This material together with ZnSb may form a promising couple for creating various thermoelectric modules. In this paper, various properties (Hall and Seebeck coefficients, electrical and thermal conductivities) are reported in the temperature range from 80 K to 797 K. Different acceptor impurities have been tested. The Hall concentration at room temperature varied from 1.5 × 1018 cm-3 to 2.7 × 1019 cm-3. Some features have been discovered in the behavior of the thermoelectric parameters of double-doped ZnSb samples at temperatures above 500 K. Their nature points to a temperature-dependent increase of the Hall concentration. The existence of two temperature ranges with additional doping is revealed by Hall coefficient and electrical conductivity measurements in the range from 80 K to 797 K. The experimental data are discussed based on a model of the energy spectrum with impurity and native defect states localized in the energy gap. It is shown that the dimensionless thermoelectric figure of merit of ZnSb: Cd, Ag, Sn is not less than 1.0 at 600 K.

  18. Grain Refinement of Deoxidized Copper

    NASA Astrophysics Data System (ADS)

    Balart, María José; Patel, Jayesh B.; Gao, Feng; Fan, Zhongyun

    2016-08-01

    This study reports the current status of grain refinement of copper accompanied in particular by a critical appraisal of grain refinement of phosphorus-deoxidized, high residual P (DHP) copper microalloyed with 150 ppm Ag. Some deviations exist in terms of the growth restriction factor (Q) framework, on the basis of empirical evidence reported in the literature for grain size measurements of copper with individual additions of 0.05, 0.1, and 0.5 wt pct of Mo, In, Sn, Bi, Sb, Pb, and Se, cast under a protective atmosphere of pure Ar and water quenching. The columnar-to-equiaxed transition (CET) has been observed in copper, with an individual addition of 0.4B and with combined additions of 0.4Zr-0.04P and 0.4Zr-0.04P-0.015Ag and, in a previous study, with combined additions of 0.1Ag-0.069P (in wt pct). CETs in these B- and Zr-treated casts have been ascribed to changes in the morphology and chemistry of particles, concurrently in association with free solute type and availability. No further grain-refining action was observed due to microalloying additions of B, Mg, Ca, Zr, Ti, Mn, In, Fe, and Zn (~0.1 wt pct) with respect to DHP-Cu microalloyed with Ag, and therefore are no longer relevant for the casting conditions studied. The critical microalloying element for grain size control in deoxidized copper and in particular DHP-Cu is Ag.

  19. Experiments on a Cooper pair insulator

    NASA Astrophysics Data System (ADS)

    Nguyen, Hung Q.

    At temperatures below 1K, nm thick a-Bi/Sb films, patterned with a nanohoneycomb array of holes, exhibit a novel electronic state consisting of localized Cooper pairs[1]. The Superconductor Insulator Transition (SIT), a phenomenon where the ground state of electrons is tuned from a superconducting to an insulating state, on this patterned homogeneous system shows a clear bosonic nature with activated transport on the insulating side. To date, this homogeneous system is the only one that shows clear evidence for the localization of Cooper pairs. Experiments are described that were performed to further characterize the properties of the localized Cooper pair state and its superconductor to insulator transitions. We show that: (i) The shape of the magnetoresistance (MR) oscillations, which indicate the presence of Cooper pairs in these multiply connected systems, depends on the geometry of the underlying substrates, but not on parameters like the temperature or thickness of the films. The magnetic field tuned SITs of films that are just thick enough to superconduct at zero magnetic field exhibit a common critical sheet resistance separating the superconducting and insulating phases in the range of 3.5 to 5kO. We also report a new type of SIT, an incommensurability driven SIT, which occurs due to the interplay of magnetic field and disorder in the arrangement of the honeycomb array of holes. (ii) The Cooper pair insulator state exhibits a giant positive MR, which peaks at a field estimated to be sufficient to break the pairs. The electrical transport on the low field side of the peak is activated. At the highest fields, it resembles G ˜ log(T), which is consistent with the behavior expected for weakly localized electrons rather than strongly localized Cooper pairs. We discuss this MR peak, compare it to that observed in other amorphous systems and propose a zero temperature phase diagram for these films.

  20. Prospects of nanostructures Bi1-XSbx for thermoelectricity

    NASA Astrophysics Data System (ADS)

    Nikolaeva, Albina A.; Konopko, Leonid A.; Huber, Tito E.; Bodiul, Pavel P.; Popov, Ivan A.

    2012-06-01

    There is renewed focus on the thermoelectric properties of Bi-Sb. Reduced dimensionality samples of these alloys, such as nanowires, may exhibit exotic behavior that relate to the properties of the surfaces of topological insulators. It has been predicted that surface states of topological insulators have large thermopower and also ultrahigh mobilities. The authors report results of magneto-thermoelectric investigation of single crystal Bi1-xSbx nanowires in a glass cover with diameters ranging from 90 nm to 5 μm. The wide-ranging antimony concentration (0.01 < x < 0.2) enabled us to study the effect of nanowire dimensionality the (bulk) semimetal (x <0.05), semi-conductor 0.08

  1. Natural versus anthropogenic inhalable aerosol chemistry of transboundary East Asian atmospheric outflows into western Japan.

    PubMed

    Moreno, Teresa; Kojima, Tomoko; Querol, Xavier; Alastuey, Andrés; Amato, Fulvio; Gibbons, Wes

    2012-05-01

    The eastward transport of aerosols exported from mainland Asia strongly influences air quality in the Japanese archipelago. The bulk of the inhalable particulate matter (PM(10)) in these intrusions comprises either natural, desert-derived minerals (mostly supermicron silicates) or anthropogenic pollutants (mostly submicron sulphates), in various states of mixing. We analyse PM(10) collected in Kumamoto, SW Japan, during three contrasting types of aerosol intrusions, the first being dominated by desert PM which became increasingly mixed with anthropogenic components as time progressed, the second being a relatively minor event mixing fine, distal desert PM with anthropogenic materials, and the third being dominated by anthropogenic pollutants. Whereas the chemistry of the natural mineral component is characterised by "crustal" elements (Si, Al, Fe, Mg, K, Li, P, Sc, V, Rb, Sr, Zr, Th, lanthanoids), the anthropogenic component is rich in secondary inorganic compounds and more toxic metallic elements (NH(4)(+), SO(4)(2-), As, Pb, Cd, Cu, Zn, Sn, Bi, Sb, and Ge). Some desert-dust (Kosa) intrusions are more calcareous than others, implicating geologically different source areas, and contain enhanced levels of NO(3)(-), probably as supermicron Ca(NO(3))(2) particles produced by chemical reaction between NOx pollutants (mostly from industry and traffic) and carbonate during atmospheric transport. The overall trace element chemistry of aerosol intrusions into Kumamoto shows low V/Rb, low NO(3)(-)/SO(4)(2-), enhanced As levels, and unfractionated La/Ce values, which are all consistent with anthropogenic sources including coal emissions rather than those derived from the refining and combustion of oil fractionates. Geographically dispersed, residual sulphatic plumes of this nature mix with local traffic (revealed by OC and EC concentrations) and industrial emissions and dissipate only slowly, due to the dominance of submicron accumulation mode PM which is atmospherically

  2. The electronic structure and thermoelectric properties of BiTl{sub 9}Te{sub 6} and SbTl{sub 9}Te{sub 6}: First-principles calculations

    SciTech Connect

    Guo, Li Bin; Ye, Lingyun; Wang, Yuan Xu Yang, Jue Ming; Yan, Yu Li; Ren, Feng Zhu

    2015-12-21

    The electronic structure and thermoelectric properties of MTl{sub 9}Te{sub 6} (M = Bi, Sb) were studied using density functional theory and the semiclassical Boltzmann theory. It is found that the band gaps of BiTl{sub 9}Te{sub 6} and SbTl{sub 9}Te{sub 6} are equal to 0.59 eV and 0.72 eV, respectively. The relative large band gap and strong coupling between Sb s and Te p are helpful to the thermoelectric properties of SbTl{sub 9}Te{sub 6}. Near the bottom of the conduction bands, the number of band valleys of SbTl{sub 9}Te{sub 6} is four and is larger than that of BiTl{sub 9}Te{sub 6} (two band valleys), which will increase its Seebeck coefficient. Although BiTl{sub 9}Te{sub 6} has a larger electrical conductivity relative to relaxation time (σ/τ) along the z-direction than that of SbTl{sub 9}Te{sub 6}, the results show that the transport properties of SbTl{sub 9}Te{sub 6} are better than those of BiTl{sub 9}Te{sub 6} possibly due to its large Seebeck coefficient. The maximum value of power factor relative to relaxation time (S{sup 2}σ/τ) for SbTl{sub 9}Te{sub 6} reaches 4.30 × 10{sup 11 }W/K{sup 2} m s at 900 K, that is, originated from its relatively large Seebeck coefficient, suggesting its promising thermoelectric performance at high temperature.

  3. Selective oxidation of alkanes and/or alkenes to valuable oxygenates

    DOEpatents

    Lin, Manhua; Pillai, Krishnan S.

    2011-02-15

    A catalyst, its method of preparation and its use for producing at least one of methacrolein and methacrylic acid, for example, by subjecting isobutane or isobutylene or a mixture thereof to a vapor phase catalytic oxidation in the presence of air or oxygen. In the case where isobutane alone is subjected to a vapor phase catalytic oxidation in the presence of air or oxygen, the product is at least one of isobutylene, methacrolein and methacrylic acid. The catalyst comprises a compound having the formula A.sub.aB.sub.bX.sub.xY.sub.yZ.sub.zO.sub.o wherein A is one or more elements selected from the group of Mo, W and Zr, B is one or more elements selected from the group of Bi, Sb, Se, and Te, X is one or more elements selected from the group of Al, Bi, Ca, Ce, Co, Fe, Ga, Mg, Ni, Nb, Sn, W and Zn, Y is one or more elements selected from the group of Ag, Au, B, Cr, Cs, Cu, K, La, Li, Mg, Mn, Na, Nb, Ni, P, Pb, Rb, Re, Ru, Sn, Te, Ti, V and Zr, and Z is one or more element from the X or Y groups or from the following: As, Ba, Pd, Pt, Sr, or mixtures thereof, and wherein a=1, 0.05

  4. Self-organized charge puddles in a three-dimensional topological material

    NASA Astrophysics Data System (ADS)

    Borgwardt, N.; Lux, J.; Vergara, I.; Wang, Zhiwei; Taskin, A. A.; Segawa, Kouji; van Loosdrecht, P. H. M.; Ando, Yoichi; Rosch, A.; Grüninger, M.

    2016-06-01

    In three-dimensional (3D) topological materials, tuning of the bulk chemical potential is of crucial importance for observing their topological properties; for example, Weyl semimetals require chemical-potential tuning to the bulk Weyl nodes, while 3D topological insulators require tuning into the bulk band gap. Such tuning is often realized by compensation, i.e., by balancing the density of acceptors and donors. Here we show that in such a compensated 3D topological material, the possibility of local chemical-potential tuning is limited by the formation of self-organized charge puddles. The puddles arise from large fluctuations of the Coulomb potential of donors and acceptors. Their emergence is akin to the case of graphene, where charge puddles are already established as a key paradigm. However, there is an important difference: Puddles in graphene are simply dictated by the static distribution of defects in the substrate, whereas we find that puddles in 3D systems self-organize in a nontrivial way and show a strong temperature dependence. Such a self-organization is revealed by measurements of the optical conductivity of the bulk-insulating 3D topological insulator BiSbTeSe2, which pinpoints the presence of puddles at low temperatures as well as their surprising "evaporation" on a temperature scale of 30-40 K. The experimental observation is described semiquantitatively by Monte Carlo simulations. These show that the temperature scale is set by the Coulomb interaction between neighboring dopants and that puddles are destroyed by thermally activated carriers in a highly nonlinear screening process. This result indicates that understanding charge puddles is crucial for the control of the chemical potential in compensated 3D topological materials.

  5. Modelling of Equilibrium Between Mantle and Core: Refractory, Volatile, and Highly Siderophile Elements

    NASA Technical Reports Server (NTRS)

    Righter, K.; Danielson, L.; Pando, K.; Shofner, G.; Lee, C. -T.

    2013-01-01

    Siderophile elements have been used to constrain conditions of core formation and differentiation for the Earth, Mars and other differentiated bodies [1]. Recent models for the Earth have concluded that the mantle and core did not fully equilibrate and the siderophile element contents of the mantle can only be explained under conditions where the oxygen fugacity changes from low to high during accretion and the mantle and core do not fully equilibrate [2,3]. However these conclusions go against several physical and chemical constraints. First, calculations suggest that even with the composition of accreting material changing from reduced to oxidized over time, the fO2 defined by metal-silicate equilibrium does not change substantially, only by approximately 1 logfO2 unit [4]. An increase of more than 2 logfO2 units in mantle oxidation are required in models of [2,3]. Secondly, calculations also show that metallic impacting material will become deformed and sheared during accretion to a large body, such that it becomes emulsified to a fine scale that allows equilibrium at nearly all conditions except for possibly the length scale for giant impacts [5] (contrary to conclusions of [6]). Using new data for D(Mo) metal/silicate at high pressures, together with updated partitioning expressions for many other elements, we will show that metal-silicate equilibrium across a long span of Earth s accretion history may explain the concentrations of many siderophile elements in Earth's mantle. The modeling includes refractory elements Ni, Co, Mo, and W, as well as highly siderophile elements Au, Pd and Pt, and volatile elements Cd, In, Bi, Sb, Ge and As.

  6. Seasonal distribution of metals in vertical and horizontal profiles of sheltered and exposed beaches on Polish coast.

    PubMed

    Bigus, Katarzyna; Astel, Aleksander; Niedzielski, Przemysław

    2016-05-15

    The distribution of alkali and heavy metals in coastal sediments of three Polish beaches was assessed. In all locations there are sandy beaches of different characteristics according to the anthropogenic impact and degree of sheltering. Core sediments collected in Czołpino and Ustka were characterized by the highest concentration of Cd, Ag, Ba, and Al, Cu, Cr, Bi, Na, respectively. Among the alkaline metals core sediments were the most abundant with Ca, Bi, Mg and Na, presenting almost stable decreasing order in all beaches. The majority of dredge material collected can be classified as light or trace contaminated by Cr, Cu, Zn, Cd and Hg. An abundance of mineralogical components in core sediments in Ustka increases in Summer and Autumn, while in Puck is stable throughout the year. The content of studied metals in core sediments collected in three Polish beaches changes both in the vertical and horizontal profiles of the beach. PMID:26975611

  7. Bulk Dirac Points in Distorted Spinels

    NASA Astrophysics Data System (ADS)

    Steinberg, Julia; Young, Steve; Zaheer, Saad; Kane, Charles; Mele, Eugene; Rappe, Andrew

    2014-03-01

    A Dirac point is characterized by four degenerate states that disperse linearly with momentum around a single point bk in the Brillouin zone. The resulting low energy theory is pseudorelativistic. A well-known example in two dimensions is graphene, which has a Fermi surface consisting exclusively of Dirac points that are responsible for many of its exotic properties. We report on an analogous Dirac-like Fermi surface in three-dimensional bulk materials in a distorted spinel structure on the basis of density functional theory (DFT) as well as tight-binding theory. The four examples we provide in this paper are BiZnSiO4, BiCaSiO4, BiMgSiO4, and BiAlInO4. A necessary characteristic of these structures is that they contain a Bi lattice which forms a hierarchy of chain-like substructures, with consequences for both fundamental understanding and materials design.

  8. Large strain under a low electric field in lead-free bismuth-based piezoelectrics

    NASA Astrophysics Data System (ADS)

    Ullah, Aman; Won Ahn, Chang; Ullah, Amir; Won Kim, Ill

    2013-07-01

    In this letter, the composition and electric field dependent strain behavior of (1 - x)Bi0.5(Na0.78K0.22)0.5TiO3-xBi(Mg0.5Ti0.5)O3 (BNKT-BMT) were investigated to develop lead-free piezoelectric materials with a large strain response at a low driving field for actuator applications. A large strain of 0.35% (Smax/Emax = 636 pm/V) at an applied field of 55 kV/cm was obtained with a composition of 4 mol. % BMT. In particular, the electric field required to deliver large strains was reduced to a level that revealed not only a large Smax/Emax of 542 pm/V at a driving field as low as 35 kV/cm, but also remarkably suppressed the large hysteresis.

  9. Petrochemistry and hydrothermal alteration within the Tyrone Igneous Complex, Northern Ireland: implications for VMS mineralization in the British and Irish Caledonides

    NASA Astrophysics Data System (ADS)

    Hollis, Steven P.; Roberts, Stephen; Earls, Garth; Herrington, Richard; Cooper, Mark R.; Piercey, Stephen J.; Archibald, Sandy M.; Moloney, Martin

    2014-06-01

    Although volcanogenic massive sulfide (VMS) deposits can form within a wide variety of rift-related tectonic environments, most are preserved within suprasubduction affinity crust related to ocean closure. In stark contrast to the VMS-rich Appalachian sector of the Grampian-Taconic orogeny, VMS mineralization is rare in the peri-Laurentian British and Irish Caledonides. Economic peri-Gondwanan affinity deposits are limited to Avoca and Parys Mountain. The Tyrone Igneous Complex of Northern Ireland represents a ca. 484-464 Ma peri-Laurentian affinity arc-ophiolite complex and a possible broad correlative of the Buchans-Robert's Arm belt of Newfoundland, host to some of the most metal-rich VMS deposits globally. Stratigraphic horizons prospective for VMS mineralization in the Tyrone Igneous Complex are associated with rift-related magmatism, hydrothermal alteration, synvolcanic faults, and high-level subvolcanic intrusions (gabbro, diorite, and/or tonalite). Locally intense hydrothermal alteration is characterized by Na-depletion, elevated SiO2, MgO, Ba/Sr, Bi, Sb, chlorite-carbonate-pyrite alteration index (CCPI) and Hashimoto alteration index (AI) values. Rift-related mafic lavas typically occur in the hanging wall sequences to base and precious metal mineralization, closely associated with ironstones and/or argillaceous sedimentary rocks representing low temperature hydrothermal venting and volcanic quiescence. In the ca. 475 Ma pre-collisional, calc-alkaline lower Tyrone Volcanic Group rift-related magmatism is characterized by abundant non-arc type Fe-Ti-rich eMORB, island-arc tholeiite, and low-Zr tholeiitic rhyolite breccias. These petrochemical characteristics are typical of units associated with VMS mineralization in bimodal mafic, primitive post-Archean arc terranes. Following arc-accretion at ca. 470 Ma, late rifting in the ensialic upper Tyrone Volcanic Group is dominated by OIB-like, subalkaline to alkali basalt and A-type, high-Zr rhyolites. These units

  10. Enzyme leaching of surficial geochemical samples for detecting hydromorphic trace-element anomalies associated with precious-metal mineralized bedrock buried beneath glacial overburden in northern Minnesota

    USGS Publications Warehouse

    Clark, Robert J.; Meier, A.L.; Riddle, G.

    1990-01-01

    One objective of the International Falls and Roseau, Minnesota, CUSMAP projects was to develop a means of conducting regional-scale geochemical surveys in areas where bedrock is buried beneath complex glacially derived overburden. Partial analysis of B-horizon soils offered hope for detecting subtle hydromorphic trace-element dispersion patterns. An enzyme-based partial leach selectively removes metals from oxide coatings on the surfaces of soil materials without attacking their matrix. Most trace-element concentrations in the resulting solutions are in the part-per-trillion to low part-per-billion range, necessitating determinations by inductively coupled plasma/mass spectrometry. The resulting data show greater contrasts for many trace elements than with other techniques tested. Spatially, many trace metal anomalies are locally discontinuous, but anomalous trends within larger areas are apparent. In many instances, the source for an anomaly seems to be either basal till or bedrock. Ground water flow is probably the most important mechanism for transporting metals toward the surface, although ionic diffusion, electrochemical gradients, and capillary action may play a role in anomaly dispersal. Sample sites near the Rainy Lake-Seine River fault zone, a regional shear zone, often have anomalous concentrations of a variety of metals, commonly including Zn and/or one or more metals which substitute for Zn in sphalerite (Cd, Ge, Ga, and Sn). Shifts in background concentrations of Bi, Sb, and As show a trend across the area indicating a possible regional zoning of lode-Au mineralization. Soil anomalies of Ag, Co, and Tl parallel basement structures, suggesting areas that may have potential for Cobalt/Thunder Baytype silver viens. An area around Baudette, Minnesota, which is underlain by quartz-chlorite-carbonate-altered shear zones, is anomalous in Ag, As, Bi, Co, Mo, Te, Tl, and W. Anomalies of Ag, As, Bi, Te, and W tend to follow the fault zones, suggesting potential

  11. Studies of Flerovium and Element 115 Homologs with Macrocyclic Extractants

    SciTech Connect

    Despotopulos, John D.

    2015-03-12

    Study of the chemistry of the heaviest elements, Z ≥ 104, poses a unique challenge due to their low production cross-sections and short half-lives. Chemistry also must be studied on the one-atom-at-a-time scale, requiring automated, fast, and very efficient chemical schemes. Recent studies of the chemical behavior of copernicium (Cn, element 112) and flerovium (Fl, element 114) together with the discovery of isotopes of these elements with half-lives suitable for chemical studies have spurred a renewed interest in the development of rapid systems designed to study the chemical properties of elements with Z ≥ 114. This dissertation explores both extraction chromatography and solvent extraction as methods for development of a rapid chemical separation scheme for the homologs of flerovium (Pb, Sn, Hg) and element 115 (Bi, Sb), with the goal of developing a chemical scheme that, in the future, can be applied to on-line chemistry of both Fl and element 115. Carrier-free radionuclides, used in these studies, of the homologs of Fl and element 115 were obtained by proton activation of high-purity metal foils at the Lawrence Livermore National Laboratory (LLNL) Center for Accelerator Mass Spectrometry (CAMS): natIn(p,n)113Sn, natSn(p,n)124Sb, and Au(p,n)197m,gHg. The carrier-free activity was separated from the foils by novel separation schemes based on ion exchange and extraction chromatography techniques. Carrier-free Pb and Bi isotopes were obtained from development of a novel generator based on cation exchange chromatography using the 232U parent to generate 212Pb and 212Bi. Macrocyclic extractants, specifically crown ethers and their derivatives, were chosen for these studies; crown ethers show high selectivity for metal ions. Finally. a potential chemical system for Fl was established based on the Eichrom Pb resin, and insight to an improved system based on thiacrown ethers is

  12. Grain refinement and texture development of cast bismuth-antimony alloy via severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Im, Jae-Taek

    The purpose of this work was to study learn about grain refinement mechanisms and texture development in cast n-type Bi90Sb10 alloy caused by severe plastic deformation. The practical objective is to produce a fine grained and textured microstructure in Bi90Sb10 alloy with enhanced thermoelectric performance and mechanical strength. In the study, twelve millimeter diameter cast bars of Bi90Sb 10 alloy were encapsulated in square cross section aluminum 6061 alloy containers. The composite bars were equal channel angular (ECAE) extruded through a 90 degree angle die at high homologous temperature. Various extrusion conditions were studied including punch speed (0.1, 0.3 and 0.6 in/min), extrusion temperature (220, 235 and 250°C), number of extrusion passes (1, 2 and 4), route (A, BC and C), and exit channel area reduction ratio (half and quarter area of inlet channel). The affect of an intermediate long term heat treatment (for 100 hours at 250°C under 10-3 torr vacuum) was explored. Processed materials were characterized by optical microscopy, x-ray diffraction, energy dispersive spectroscopy, wavelength dispersive spectroscopy and scanning electron microscopy. Texture was analyzed using the {006} reflection plane to identify the orientation of the basal poles in processed materials. The cast grains were irregularly shaped, had a grain size of hundreds-of-microns to millimeters, and showed inhomogeneous chemical composition. Severe plastic deformation refines the cast grains through dynamic recrystallization and causes the development of a bimodal microstructure consisting of fine grains (5-30 micron) and coarse grains (50-300 micron). ECAE processing of homogenizied Bi-Sb alloy causes grain refinement and produces a more uniform microstructure. Texture results show that ECAE route C processing gives a similar or slightly stronger texture than ECAE route A processing. In both cases, the basal-plane poles become aligned with the shear direction. Reduction area exit

  13. Characterization of energy critical elements in ore resources and associated waste tailings: Implications for recovery and remediation

    NASA Astrophysics Data System (ADS)

    McClenaghan, Sean H.

    2015-04-01

    The occurrence of Energy Critical Elements (ECE) in primary ore minerals and their subsequent enrichment in waste tailings is of great metallurgical interest. Recovery of many ECEs, in particular In, Ge, and Ga have come chiefly as a by-product of base-metal production (smelting and refining); these elements are found only at very low levels in the Earth's crust and do not typically form economic deposits on their own. As the ECEs become more important for a growing number of technological applications, it is critical to map the distribution of these elements in ore and waste (gangue) minerals to optimize their recovery and remediation. The characterization and beneficiation of ECEs is best illustrated for Zn-rich ore systems, where a mineral such as sphalerite (ZnS) will concentrate a number of major (Fe, Mn) and important trace elements (Cd, Se, In, Ge, Te, Sn, Bi, Sb, Hg). Interestingly, the mineral chemistry of sphalerite will often differ between different styles of mineralization (i.e., granite-hosted veins versus volcanic-hosted massive sulfides) and can even exhibit considerable variability within a deposit in response to metal zonation across hydrothermal facies. This has significant metallurgical implications for the blending of ore resources, the efficient production of Zn concentrates, and their ultimate value during the smelting and refining stages. Gangue minerals transferred to waste tailings may also exhibit significant enrichment in ECEs and precious metals; including Au in pyrite-arsenopyrite, and rare earth elements in a range of carbonate and phosphate minerals. In situ micro-analytical techniques are ideal for the quantitative measurement of trace elements in ore minerals as well as associated gangue materials. Recent advances in ICP-MS and ICP-OES technology coupled with newer classes of UV Excimer lasers (native 193 nm light) have allowed for more discrete analyses, permitting micro-chemical mapping at small scales (<10 microns). Further

  14. Magnetic Topological Insulators and Quantum Anomalous Hall Effect

    NASA Astrophysics Data System (ADS)

    Kou, Xufeng

    The engineering of topological surface states is a key to realize applicable devices based on topological insulators (TIs). Among various proposals, introducing magnetic impurities into TIs has been proven to be an effective way to open a surface gap and integrate additional ferromagnetism with the original topological order. In this Dissertation, we study both the intrinsic electrical and magnetic properties of the magnetic TI thin films grown by molecular beam epitaxy. By doping transition element Cr into the host tetradymite-type V-VI semiconductors, we achieve robust ferromagnetic order with a strong perpendicular magnetic anisotropy. With additional top-gating capability, we realize the electric-field-controlled ferromagnetism in the magnetic TI systems, and demonstrate such magneto-electric effects can be effectively manipulated, depending on the interplays between the band topology, magnetic exchange coupling, and structural engineering. Most significantly, we report the observation of quantum anomalous Hall effect (QAHE) in the Cr-doped (BiSb)2Te3 samples where dissipationless chiral edge conduction is realized in the macroscopic millimeter-size devices without the presence of any external magnetic field, and the stability of the quantized Hall conductance of e2/h is well-maintained as the film thickness varies across the 2D hybridization limit. With additional quantum confinement, we discover the metal-to-insulator switching between two opposite QAHE states, and reveal the universal QAHE phase diagram in the thin magnetic TI samples. In addition to the uniform magnetic TIs, we further investigate the TI/Cr-doped TI bilayer structures prepared by the modulation-doped growth method. By controlling the magnetic interaction profile, we observe the Dirac hole-mediated ferromagnetism and develop an effective way to manipulate its strength. Besides, the giant spin-orbit torque in such magnetic TI-based heterostructures enables us to demonstrate the current

  15. Mineralogy of the Precambrian southern Kostomuksha gold prospect in Karelia

    NASA Astrophysics Data System (ADS)

    Kuleshevich, L. V.; Gor'kovets, V. Ya.

    2008-12-01

    The southern Kostomuksha gold-sulfide prospect with a grade of 0.2-30 g/t Au belongs to the gold-pyrrhotite-arsenopyrite mineral type and is localized in the metasomatically altered shear zone at the southern flank of the Kostomuksha iron deposit. The Au-bearing pyrite ore is commonly characterized by a low grade (0.02-1.0 g/t Au). The grade of Au-bearing mineralization composed of arsenopyrite, loellingite, and electrum (4.28-15.31 wt % Ag and up to 0.99-2.16 wt % Hg) is higher; pyrrhotite, chalcopyrite, galena, maldonite, aurostibite, and native bismuth are additional components of this mineral assemblage. The ore mineralization is hosted in the near-latitudinal shear zone close to the contact between the folded and metamorphosed banded iron formation (BIF) and hälleflinta. The early stage of collision-related HP-HT metamorphism resulted in the formation of a garnet-amphibole-biotite assemblage ( T = 680-750°C) and microcline. After an abrupt drop m pressure, metasomatic alteration and ore mineralization took place. The ore-forming process started at 510-440°C with deposition of arsenopyrite. Galena and electrum were formed at a lower temperature. The temperature continued to decline down to the stage of ore oxidation and deposition of colloform marcasite. Ore minerals precipitated from acid chloride aqueous solutions admixed with methane at the initial stage and from diluted aqueous solutions at the final stage. The character of wall-rock alteration and the gain of K, Rb, and B show that the ore-forming process postdated the emplacement of potassium granite. The occurrence of Cu, Zn, Pb, As, and Ni and other heterogeneous elements indicates a complex metamorphic-metasomatic source and an additional supply of Au, As, Bi, Sb, and Te under conditions of sulfur deficiency. The gold mineralization at the southern Kostomuksha prospect is classified as gold-sulfide (arsenopyrite) ore type related to shear zones in the BIF.

  16. Prospects of nanostructures Bi{sub 1-x}Sb{sub x} for thermoelectricity

    SciTech Connect

    Nikolaeva, Albina A.; Konopko, Leonid A.; Huber, Tito E.; Bodiul, Pavel P.; Popov, Ivan A.

    2012-09-15

    It has been predicted that surface states of topological insulators have large a thermopower and also ultrahigh mobilities. The authors report results of a magneto-thermoelectric investigation of single crystal Bi{sub 1-x}Sb{sub x} nanowires in a glass cover with diameters ranging from 90 nm to 5 {mu}m. The wide-ranging antimony concentration enabled us to study the effect of nanowire dimensionality in the semimetal, semi-conductor and gapless regimes. Quantum size effects in Bi-2 at%Sb nanowires, which are shown in temperature dependences of resistance R(T) and thermopower {alpha}(T) for the diameters significantly higher than the critical diameter for pure Bi-wires, are observed. The thermopower in weak magnetic fields, reaches values +400 {mu}V/K at T=20-40 K. Power factor {alpha}{sup 2}{sigma} depending on diameter of wires, structure, temperature and magnetic field is calculated. In connection with topological insulators, we will discuss the surface effect in the thermoelectric properties that we observe. - Graphical abstract: Temperature dependences of resistance R{sub T}/R{sub 300}(T) (a) for Bi-2 at%Sb wires various diameters d: 1-d=300 nm, 2-d=400 nm, 3-d=600 nm, 4-d=1600 nm. Inset (a) SEM cross sectional image of the 650 nm Bi-2 at%Sb wire (clear) in glass envelope (gray). The magnetic field dependences thermopower (H Double-Vertical-Line {Delta}T) (b) Bi-2 at%Sb wires, with different diameters: (1). d=300 nm, (2). d=400 nm, (3). d=600 nm, T=26 K. Highlights: Black-Right-Pointing-Pointer SMSC transition in semimetal Bi-Sb wires due to the quantum size effect is observed. Black-Right-Pointing-Pointer In Bi-6 at%Sb wires alloys has been realized the gapless (GL) state. Black-Right-Pointing-Pointer In the area GS state abnormal growth thermopower in magnetic fields is found out. Black-Right-Pointing-Pointer Semiconductor Bi{sub 1-x} Sb{sub x} nanowires manifest properties of the topological insulators.

  17. The effects of nanoparticle inclusions upon the microstructure and thermoelectric transport properties of bismuth telluride-based composites

    NASA Astrophysics Data System (ADS)

    Gothard, Nicholas Wesley

    was adopted in order to consolidate the nanostructures into the bulk matrix. Nanocomposites were produced using both n-type and p-type bismuth telluride compounds as the matrix material, into which nanostructures of Bi2Te 3, BiSb, Bi2S3, as well as Au and Ag nanoparticles and C60 were incorporated. The preferred consolidation technique utilized a 3-axis mechanical mixer, followed first by cold and then hot pressing of the bulk-nano mixtures. The composites were studied with respect to their microstructure and elemental composition, as well as with regard to their thermal and electrical transport properties. The effects of the nanoparticle additions upon the efficiencies of the materials are presented, and the viability of improving the thermoelectric performance of this class of materials by this method is considered.

  18. Effects of simulated acid rain, EDTA, or their combination, on migration and chemical fraction distribution of extraneous metals in Ferrosol.

    PubMed

    Wen, Fang; Hou, Hong; Yao, Na; Yan, Zengguang; Bai, Liping; Li, Fasheng

    2013-01-01

    A laboratory repacked soil-leaching column experiment was conducted to study the effects of simulated acid rain or EDTA by themselves or in combination, on migration and chemical speciation distribution of Pb and its alternative rare metals including Ag, Bi, In, Sb, and Sn. Experimental results demonstrate that leaching with simulated acid rain promoted the migration of Bi, In and Pb, and their migration reached down to 8 cm in the soil profile, no enhancement of Sb, Ag or Sn migration was observed. Addition of EDTA significantly enhanced the migration of all six metals, especially Bi, In and Pb. The migration of metals was in the order Pb>Bi>In>Sb>Sn>Ag. The individual and combined effects of acid rain and EDTA increased the environmental risk of metals, by increasing the soluble content of metals in soil solutions and the relative distribution of the exchangeable fraction. Leaching risks of Bi, In and Pb were higher than other three metals. PMID:22921654

  19. Enhancement of Rashba interaction in GaAs/AlGaAs quantum wells due to the incorporation of bismuth

    SciTech Connect

    Simmons, R. A.; Jin, S. R.; Sweeney, S. J.; Clowes, S. K.

    2015-10-05

    This paper reports on the predicted increase in the Rashba interaction due to the incorporation of Bi in GaAs/AlGaAs heterostructures. Band structure parameters obtained from the band anti-crossing theory have been used in combination with self-consistent Schrödinger-Poisson calculations and k.p models to determine the electron spin-splitting caused by structural inversion asymmetry and increased spin-orbit interaction. A near linear seven fold increase in the strength of the Rashba interaction is predicted for a 10% concentration of Bi in a GaAsBi/AlGaAs quantum well heterostructure.

  20. Interface stability of electrode/Bi-containing relaxor ferroelectric oxide for high-temperature operational capacitor

    NASA Astrophysics Data System (ADS)

    Nagata, Takahiro; Kumaragurubaran, Somu; Tsunekawa, Yoshifumi; Yamashita, Yoshiyuki; Ueda, Shigenori; Takahashi, Kenichiro; Ri, Sung-Gi; Suzuki, Setsu; Oh, Seungjun; Chikyow, Toyohiro

    2016-06-01

    The interface stability between electrodes (Pt, TaC, TiC, and RuO2) and a Bi-containing relaxor ferroelectric oxide, BaTiO3–Bi(Mg2/3Nb1/3)O3 (BT–BMN), applied to a high-temperature operational capacitor was investigated by hard X-ray photoelectron spectroscopy. All the electrodes showed electron filling at the Fermi level after annealing at 400 °C. However, Pt and TaC indicated electrical property degradations due to the thick intermediate layer formation and defect formation of the BT–BMN layer relating to the Bi diffusion into the electrodes. In contrast, TiC inhibited the Bi diffusion and did not show any change in the band alignment after annealing. Furthermore, RuO2 eliminated the defect formation in BT–BMN and showed no change in the band alignment although the Bi diffusion was also observed. These results suggest that the TiC/RuO2/BT–BMN stack structure is a potential candidate for the high-temperature operational capacitor.

  1. Dielectric Properties and Complex Impedance Analysis of BT-BMT-BS Ceramics

    NASA Astrophysics Data System (ADS)

    Muhammad, Raz; Khesro, Amir; Uzair, Muhammad

    2016-08-01

    Polycrystalline (1- x)BaTiO3-0.5 xBi(Mg0.5Ti0.5)O3-0.5 xBiScO3 ( x = 0.4, 0.45, 0.5, and 0.55) samples have been prepared via a conventional mixed-oxide solid-state sintering route. Phase analysis of the samples with x ≥ 0.45 revealed formation of single-phase cubic structure, while at x = 0.4, a minor secondary phase formed. Complex impedance spectroscopy of the samples revealed more than one type of transport mechanism (grain/bulk, grain boundary, and electrode effect). At x = 0.4, the grain boundary was less conducting than the grain; however, grains dominated the total conductivity with further increase in x. At elevated temperatures, the higher conductivity values suggest semiconducting-like behavior with negative temperature coefficient of resistivity. The composition with x = 0.55 exhibited a temperature-stable relative permittivity ( ɛ r) of 1430 (±15% over 127°C to 500°C) and dielectric loss (tan δ) of <0.025 (over 150°C to 370°C).

  2. Lead-free ternary perovskite compounds with large electromechanical strains

    NASA Astrophysics Data System (ADS)

    Jarupoom, Parkpoom; Patterson, Eric; Gibbons, Brady; Rujijanagul, Gobwute; Yimnirun, Rattikorn; Cann, David

    2011-10-01

    Lead-free compounds based on perovskite solid solutions in the ternary system (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-Bi(X1/2Ti1/2)O3, where X = Ni and Mg have been shown to exhibit large electromechanical strains. While the perovskite end members Bi(Mg1/2Ti1/2)O3 and Bi(Ni1/2Ti1/2)O3 display limited stability in their pure state, both compounds were found to have solid solubilities of at least 50 mol. % with (Bi1/2Na1/2)TiO3 and (Bi1/2K1/2)TiO3. Most importantly, under relatively large applied fields, these materials exhibited large hysteretic electromechanical strains characterized by a parabolic shape. With effective piezoelectric coefficients (d33*) greater than 500 pm/V, these systems have excellent potential as a Pb-free piezoelectric materials.

  3. Dielectric Properties and Complex Impedance Analysis of BT-BMT-BS Ceramics

    NASA Astrophysics Data System (ADS)

    Muhammad, Raz; Khesro, Amir; Uzair, Muhammad

    2016-05-01

    Polycrystalline (1-x)BaTiO3-0.5xBi(Mg0.5Ti0.5)O3-0.5xBiScO3 (x = 0.4, 0.45, 0.5, and 0.55) samples have been prepared via a conventional mixed-oxide solid-state sintering route. Phase analysis of the samples with x ≥ 0.45 revealed formation of single-phase cubic structure, while at x = 0.4, a minor secondary phase formed. Complex impedance spectroscopy of the samples revealed more than one type of transport mechanism (grain/bulk, grain boundary, and electrode effect). At x = 0.4, the grain boundary was less conducting than the grain; however, grains dominated the total conductivity with further increase in x. At elevated temperatures, the higher conductivity values suggest semiconducting-like behavior with negative temperature coefficient of resistivity. The composition with x = 0.55 exhibited a temperature-stable relative permittivity (ɛ r) of 1430 (±15% over 127°C to 500°C) and dielectric loss (tan δ) of <0.025 (over 150°C to 370°C).

  4. 47 CFR 15.407 - General technical requirements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... National Information Infrastructure Devices § 15.407 General technical requirements. (a) Power limits: (1... maximum conducted output power over the frequency band of operation shall not exceed 1 W provided the maximum antenna gain does not exceed 6 dBi. In addition, the maximum power spectral density shall...

  5. The COBRA Double Beta Decay Experiment

    NASA Astrophysics Data System (ADS)

    Dawson, J. V.

    2007-03-01

    The progress of the COBRA neutrinoless double beta decay experiment is discussed. Potential backgrounds are described. Estimates on the contamination levels of 214Bi in the detectors have been made using previously acquired low background data. New crystals with a different passivation material show an improved background count rate of approximately one order of magnitude.

  6. Bibliographic Instruction in Academic Libraries. A Review of the Literature and Selected Bibliography.

    ERIC Educational Resources Information Center

    Morris, Jacquelyn M.

    This overview of bibliographic instruction (B.I.) in college and university libraries provides a brief review of the literature, proposes an indexing language based on the special terminology of the field for more precise literature searches, and presents a 174-item bibliography of journal articles, books, and ERIC documents. The literature review…

  7. Impact of Behavioral Inhibition and Parenting Style on Internalizing and Externalizing Problems from Early Childhood through Adolescence

    ERIC Educational Resources Information Center

    Williams, Lela Rankin; Degnan, Kathryn A.; Perez-Edgar, Koraly E.; Henderson, Heather A.; Rubin, Kenneth H.; Pine, Daniel S.; Steinberg, Laurence; Fox, Nathan A.

    2009-01-01

    Behavioral inhibition (BI) is characterized by a pattern of extreme social reticence, risk for internalizing behavior problems, and possible protection against externalizing behavior problems. Parenting style may also contribute to these associations between BI and behavior problems (BP). A sample of 113 children was assessed for BI in the…

  8. The Potential Role of Business Intelligence in Church Organizations

    ERIC Educational Resources Information Center

    Felder, Charmaine

    2012-01-01

    Business intelligence (BI) involves transforming data into actionable information to make better business decisions that may help improve operations. Although businesses have experienced success with BI, how leaders of church organizations might be able to exploit the advantages of BI in church organizations remains largely unexplored. The purpose…

  9. Thermally-Labile Trace Elements in Enstatite Meteorites

    NASA Technical Reports Server (NTRS)

    Wang, M.-S.; Lipschutz, M. E.

    2000-01-01

    RNAA data for Bi, In and Tl in 30 E3-6 chondrites accord well with trends for heated Abee (EH4) suggesting that all EH and EL samples reflect open-system, post-accretionary heating, independent of siderophile content or recovery location.

  10. Temperament and Family Environment in the Development of Anxiety Disorder: Two-Year Follow-Up

    ERIC Educational Resources Information Center

    Hudson, Jennifer L.; Dodd, Helen F.; Lyneham, Heidi J.; Bovopoulous, Nataly

    2011-01-01

    Objective: Behavioral inhibition (BI) in early childhood is associated with increased risk for anxiety. The present research examines BI alongside family environment factors, specifically maternal negativity and overinvolvement, maternal anxiety, and mother-child attachment, with a view to providing a broader understanding of the development of…

  11. Endothelial Expression of Scavenger Receptor Class B, Type I Protects against Development of Atherosclerosis in Mice

    PubMed Central

    Vaisman, Boris L.; Vishnyakova, Tatyana G.; Freeman, Lita A.; Amar, Marcelo J.; Demosky, Stephen J.; Liu, Chengyu; Stonik, John A.; Sampson, Maureen L.; Pryor, Milton; Bocharov, Alexander V.; Eggerman, Thomas L.; Patterson, Amy P.; Remaley, Alan T.

    2015-01-01

    The role of scavenger receptor class B, type I (SR-BI) in endothelial cells (EC) was examined in several novel transgenic mouse models expressing SR-BI in endothelium of mice with normal C57Bl6/N, apoE-KO, or Scarb1-KO backgrounds. Mice were also created expressing SR-BI exclusively in endothelium and liver. Endothelial expression of the Tie2-Scarb1 transgene had no significant effect on plasma lipoprotein levels in mice on a normal chow diet but on an atherogenic diet, significantly decreased plasma cholesterol levels, increased plasma HDL cholesterol (HDL-C) levels, and protected mice against atherosclerosis. In 8-month-old apoE-KO mice fed a normal chow diet, the Tie2-Scarb1 transgene decreased aortic lesions by 24%. Mice expressing SR-BI only in EC and liver had a 1.5 ± 0.1-fold increase in plasma cholesterol compared to mice synthesizing SR-BI only in liver. This elevation was due mostly to increased HDL-C. In EC culture studies, SR-BI was found to be present in both basolateral and apical membranes but greater cellular uptake of cholesterol from HDL was found in the basolateral compartment. In summary, enhanced expression of SR-BI in EC resulted in a less atherogenic lipoprotein profile and decreased atherosclerosis, suggesting a possible role for endothelial SR-BI in the flux of cholesterol across EC. PMID:26504816

  12. 12 CFR 218.700 - Defined terms relating to the networking exception from the definition of “broker.”

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    .... 78c(a)(4)(B)(i)) in the context of transactions with a customer, the following terms shall have the... be contingent on whether a customer: (1) Contacts or keeps an appointment with a broker or dealer as... by the bank or broker or dealer for customer referrals, including such criteria as minimum...

  13. The Teaching of Critical Thinking Skills by Academic Librarians.

    ERIC Educational Resources Information Center

    Goetzfridt, Nicholas J.

    Teaching critical thinking is a relatively new dimension of bibliographic instruction (BI) in the academic environment. It marks a departure from the teaching of "user skills" in which the primary concern is enabling library patrons to determine the appropriateness of reference tools and to use those tools effectively. This report assembles a…

  14. 3. VIEW OF WATER TANKS FROM ACCESS ROAD TO HATCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW OF WATER TANKS FROM ACCESS ROAD TO HATCH ADIT. VIEW NORTH. LUCKY TIGER MILL OFFICE (FEATURE B-I) IN DISTANCE. (OCTOBER, 1995) - Nevada Lucky Tiger Mill & Mine, Water Tanks, East slope of Buckskin Mountain, Paradise Valley, Humboldt County, NV

  15. 31 CFR 30.10 - Q-10: What actions are necessary for a TARP recipient to comply with section 111(b)(3)(D) of EESA...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 31 Money and Finance: Treasury 1 2011-07-01 2011-07-01 false Q-10: What actions are necessary for... right to a bonus payment, see 26 CFR 1.409A-1(b)(i). In addition, the bonus payment must be made in....10 Section 30.10 Money and Finance: Treasury Office of the Secretary of the Treasury TARP...

  16. 31 CFR 30.10 - Q-10: What actions are necessary for a TARP recipient to comply with section 111(b)(3)(D) of EESA...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 31 Money and Finance: Treasury 1 2014-07-01 2014-07-01 false Q-10: What actions are necessary for... right to a bonus payment, see 26 CFR 1.409A-1(b)(i). In addition, the bonus payment must be made in....10 Section 30.10 Money and Finance: Treasury Office of the Secretary of the Treasury TARP...

  17. 31 CFR 30.10 - Q-10: What actions are necessary for a TARP recipient to comply with section 111(b)(3)(D) of EESA...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 31 Money and Finance: Treasury 1 2013-07-01 2013-07-01 false Q-10: What actions are necessary for... right to a bonus payment, see 26 CFR 1.409A-1(b)(i). In addition, the bonus payment must be made in....10 Section 30.10 Money and Finance: Treasury Office of the Secretary of the Treasury TARP...

  18. The COBRA Double Beta Decay Experiment

    SciTech Connect

    Dawson, J. V.

    2007-03-28

    The progress of the COBRA neutrinoless double beta decay experiment is discussed. Potential backgrounds are described. Estimates on the contamination levels of 214Bi in the detectors have been made using previously acquired low background data. New crystals with a different passivation material show an improved background count rate of approximately one order of magnitude.

  19. 31 CFR 30.10 - Q-10: What actions are necessary for a TARP recipient to comply with section 111(b)(3)(D) of EESA...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... right to a bonus payment, see 26 CFR 1.409A-1(b)(i). In addition, the bonus payment must be made in... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Q-10: What actions are necessary for....10 Section 30.10 Money and Finance: Treasury Office of the Secretary of the Treasury TARP...

  20. Theoretical study on transport properties of topological states of matter

    NASA Astrophysics Data System (ADS)

    Hsu, Hsiu-Chuan

    larger conductance appears for half-integer magnetic flux, leading to magnetoconductance oscillations with a period equivalent to one magnetic flux quantum. Our numerical simulation of the magnetoconductance oscillations is supported by experimental observations in resistive Bi 2Te3 nanotubes. Another system that we study is the quantum anomalous Hall insulator. Similar to the quantum Hall effect, the Hall conductance is quantized and the longitudinal resistance drops to zero in the quantum anomalous Hall effect. However, the quantum anomalous Hall effect is realized in a magnetic system in absence of external magnetic fields and the associated Landau levels. The quantum anomalous Hall effect was first proposed in magnetically doped HgTe quantum wells. However, one obstacle is that this system is paramagnetic, and thus external magnetic fields are required to polarize magnetization and inevitably leads to Landau levels. In this study, we focus on the role of in-plane magnetic fields and find that the quantum anomalous Hall effect can be realized by a purely in-plane magnetic field when there is strain in the system. Symmetry analysis is adopted to provide more theoretical insight of the underlying physics. Without any strain, we explore how to extract the role of magnetization in the standard transport measurement of Hall resistance by rotating magnetic fields. Our results provide a guidance to the recent experiments in Mn doped HgTe quatnum wells with rotating magnetic fields. Besides these studies, we also investigate anisotropic magneto-conductance in magnetically doped (Bi,Sb)2Te3 films. The studies in the dissertation are in a close collaboration with transport measurements of experimental groups, including magneto-conductance oscillation observed by Qi's group at Penn State and the study of the Hall conductance in Mn doped HgTe quantum wells with rotating magnetic fields by Molenkamp's group at Wuerzburg University.

  1. Facile synthesis of bismuth(III) and antimony(III) complexes supported by silylated calix[5]arenes.

    PubMed

    Mendoza-Espinosa, Daniel; Hanna, Tracy A

    2009-11-01

    A series of bismuth(III) and antimony(III) complexes supported by silicon-containing calix[5]arene ligands were synthesized and fully characterized by NMR, X-ray, IR, mp, UV/vis, and elemental analysis. Reaction of the para-tert-butylcalix[5]arene [(t)BuC5(H)(5)] disodium salt, Na(2) x (t)BuC5(H)(3), with 1 equiv of R(2)SiCl(2) (R = Me, (i)Pr, Ph, CH=CH(2)) or treatment of the (t)BuC5(H)(5) lower rim monobenzyl ether [(t)BuC5(Bn)(H)(4)] in a 1:1 ratio with Me(2)Si(NMe(2))(2) yields the (t)BuC5(SiRR')(H)(3) (1-5) and (t)BuC5(Bn)(SiMe(2))(H)(2) (6) ligands, respectively. The (1)H NMR spectra of the (t)BuC5(SiRR')(H)(3) (1-5) ligands show three pairs of doublets and three singlets for the (t)Bu peaks, consistent with a C(s) symmetry. In the case of the (t)BuC5(Bn)(SiMe(2))(H)(2) (6) ligand, the presence of the monobenzyl group changes the (1)H NMR patterns to indicate a C(1) symmetry. Treatment of (t)BuC5(SiRR')(H)(3) (1-5) or (t)BuC5(Bn)(SiMe(2))(H)(2) (6) with 1 equiv of M(O(t)Bu)(3) (M = Bi, Sb) or Sb(NMe(2))(2) readily yields metalated products of the type [M{(t)BuC5(SiRR')}] (7-16) and [MX{(t)BuC5(Bn)(SiMe(2))}] (X = O(t)Bu, (NMe(2))(2)) (17-19), respectively. All monometallic complexes [M{(t)BuC5(SiRR')}] (7-19) display excellent solubility in organic solvents including pentane and hexane. The (1)H NMR patterns for complexes 7-16 are consistent with a 1,2- or 1,3-alternate conformation while complexes [MX{(t)BuC5(Bn)(SiMe(2))}] (17-19) display patterns for a C(1) symmetry. All crystals show monomeric structures. Ligand (t)BuC5(SiPh(2))(H)(3) (3) displays a distorted cone conformation while the presence of the monobenzyl ether in (t)BuC5(Bn)(SiMe(2))(H)(2) (6) forces a partial cone conformation. Complexes 7-19 all display a distorted 1,2-alternate conformation with the metal centers displaying coordination numbers of three, four or five. No Si...M interactions were observed. PMID:19785468

  2. A fluid inclusion and isotopic study of an intrusion-related gold deposit (IRGD) setting in the 380 Ma South Mountain Batholith, Nova Scotia, Canada: evidence for multiple fluid reservoirs

    NASA Astrophysics Data System (ADS)

    Kontak, Daniel J.; Kyser, Kurt

    2011-04-01

    A set of sheeted quartz veins cutting 380 Ma monzogranite at Sandwich Point, Nova Scotia, Canada, provide an opportunity to address issues regarding fluid reservoirs and genesis of intrusion-related gold deposits. The quartz veins, locally with arsenopyrite (≤5%) and elevated Au-(Bi-Sb-Cu-Zn), occur within the reduced South Mountain Batholith, which also has other zones of anomalous gold enrichment. The host granite intruded ( P = 3.5 kbars) Lower Paleozoic metaturbiditic rocks of the Meguma Supergroup, well known for orogenic vein gold mineralization. Relevant field observations include the following: (1) the granite contains pegmatite segregations and is cut by aplitic dykes and zones (≤1-2 m) of spaced fracture cleavage; (2) sheeted veins containing coarse, comb-textured quartz extend into a pegmatite zone; (3) arsenopyrite-bearing greisens dominated by F-rich muscovite occur adjacent the quartz veins; and (4) vein and greisen formation is consistent with Riedel shear geometry. Although these features suggest a magmatic origin for the vein-forming fluids, geochemical studies indicate a more complex origin. Vein quartz contains two types of aqueous fluid inclusion assemblages (FIA). Type 1 is a low-salinity (≤3 wt.% equivalent NaCl) with minor CO2 (≤2 mol%) and has T h = 280-340°C. In contrast, type 2 is a high-salinity (20-25 wt.% equivalent NaCl), Ca-rich fluid with T h = 160-200°C. Pressure-corrected fluid inclusion data reflect expulsion of a magmatic fluid near the granite solidus (650°C) that cooled and mixed with a lower temperature (400°C), wall rock equilibrated, Ca-rich fluid. Evidence for fluid unmixing, an important process in some intrusion-related gold deposit settings, is lacking. Stable isotopic (O, D, S) analyses for quartz, muscovite and arsenopyrite samples from vein and greisens indicate the following: (1) δ18Oqtz = +11.7‰ to 17.8‰ and δ18Omusc = +10.7‰ to +11.2‰; (2) δDmusc = -44‰ to-54‰; and (3) δ34Saspy = +7.8

  3. Application of the superfine fraction analysis method in ore gold geochemical prospecting in the Shamanikha-Stolbovsky Area (Magadan Region)

    NASA Astrophysics Data System (ADS)

    Makarova, Yuliya; Sokolov, Sergey; Glukhov, Anton

    2014-05-01

    potential gold zones, and determine their formation affinity. Nadezhda Site. Contrast Au, Ag, Pb, Bi, Sb, As dispersion halos that form a linear anomalous geochemical field of ore body rank are identified. Predicted mineralization was related to the gold-sulfosalt mineral association according to the secondary dispersion halos chemical composition. Timsha Site. Contrast secondary Au, Ag, Sb, As, Hg, Pb, Bi dispersion halos are identified. These halos have rhythmically-banded structure, which can be caused by stringer morphological type of mineralization. Bands with anomalously high contents of elements have been interpreted by the authors as probable auriferous bodies. Four such bodies of 700 to 1500 m long were identified. Mineralization of the gold-sulfide formation similar to the "Carlin" type is predicted according to the secondary dispersion halos chemical composition as well as geological features. Temny Site. Contrast secondary Au, Ag, W, Sb dispersion halos are identified. A series of geochemical associations was identified based on factor analysis results. Au-Bi-W-Hg, and Pb-Sb-Ag-Zn associations, apparently related to the mineralization are of the greatest interest. Geochemical fields of these associations are closely spaced and overlapped in plan that may be caused by axial zoning of the subvertically dipping auriferous body. Three linear geochemical zones corresponding to potentially auriferous zones with pyrite type mineralization of the gold-quartz formation are identified within the anomalous geochemical field core zone. 3. In all these prospects, mining and drilling penetrated gold ore bodies within the identified potentially gold zones. The Nadezhda target now has the status of gold deposit.

  4. Geochemical features of the Osovey Area, perspective for the polymetallic mineralization revealing (Polar Urals)

    NASA Astrophysics Data System (ADS)

    Savicheva, Olga; Sholokhnev, Vladimir; Makarova, Yuliya

    2014-05-01

    Osovey prospective area (184 km2) is located in the north of the Polar Urals within the Verhnekarsk Eletsk metallogenic zone, specialized on the base metals, barium and bauxite. Three structural stages, namely Riphean-Early Cambrian, the Late Carboniferous, and Triassic-Cenozoic are identified in the geological structure of the area. They are divided by the stratigraphic and angular unconformity. Volcaniclastic rocks of the Oyuyahinskaay Formation such as basaltic andesite, apovolcanogenic shales, mediosilicic and basic composition tuffs, as well as black banded shales of carbon-clay-siliceous composition related to the Silurian-Early Devonian Harotskaay Formation are predominant. Area is characterized by complex landscape conditions for the prospecting. Increased thickness of loose sediments, transeluvial weakly dissected lowlands, superaqual landscapes in lower parts of the slopes are widespread. In 2012 at the 1:50 000 scale geochemical prospecting (sampling density 500×50 m), carried out in the Osovey Area, 6000 samples were picked out from unconsolidated sediments. The samples were analyzed by the ICP MS method. Principal typomorphic elements of the polymetallic mineralization (Zn, Pb, Cu, Ag) as well as elements-indicators such as Bi, Sb, Se, Mo, etc. were defined. In addition to the polymetallic mineralization the Osoveysky area is perspective on the identification of iron-manganese ores, barites with polymetals, phosphorites, and vanadium. Such elements as Mn, P, V, U, Ba were also defined for this reason. Contrast secondary dispersion halos of Cu (up to 2060 ppm), Ag (1,45 ppm), Sb (12,3 ppm), Mo (18,9 ppm), Mn (7, 6 %), P (1,05%), Ni (338 ppm), and medium-low contrast ones of Zn, Pb, Co, V, Se, Sr, Bi, Sn, Ba, Ti, U, Cr, Zr were identified according to the results of the geochemical prospecting. Five anomalous geochemical fields (AGF) of the ore deposit rank (n ×100 km2) were identified according to the results of geochemical data processing and their

  5. EDITORIAL: Progress in topological insulators Progress in topological insulators

    NASA Astrophysics Data System (ADS)

    Morpurgo, Alberto; Trauzettel, Björn

    2012-12-01

    One of the most remarkable discoveries of the last few years in condensed matter physics is that the established distinction of crystalline solids in metals and insulators—which relies on the material band-structure—is incomplete. During the last several decades, the band structure of an uncountable variety of compounds of increasing complexity have been computed, and yet it has been overlooked that in the presence of sufficiently strong spin-orbit interaction, a new class of materials can be realized, that intrinsically behaves as insulators in their bulk and as metals at their surface. The discovery of this new class of materials was made only recently by Kane and Mele, during their theoretical studies of graphene in the presence of a sufficiently strong intrinsic spin-orbit interaction. Although the strength of the spin-orbit interaction in graphene is not sufficient to make the topological insulating state visible experimentally under currently reachable conditions, the validity and the originality of the concept were fully appreciated. Predictions for the occurrence of a two-dimensional topological insulating state in HgTe/CdTe heterostructures were made by Bernevig, Hughes and Zhang, and were followed by the experimental verification at Würzburg, in the Molenkamp group. Within a couple of years, this work brought the concept of topological insulator from an abstract theoretical discovery to an experimental reality, which stimulated further work. The concept of topological insulators was extended to the case of three-dimensional systems, for which an ideal experimental probe is angle-resolved photo-emission spectroscopy. Using this technique, specific theoretical predictions that had been made regarding the topological insulating character of different materials (e.g., for Bi-based compounds such as BiSb, Bi2Se3 or Bi2Te3), were verified experimentally through the direct observation of the Dirac surface fermions. This research was sufficient to put on

  6. The origin of halide melt phases in layered intrusions, and their significance to platinum-group element mobility

    NASA Astrophysics Data System (ADS)

    Hanley, J. J.

    2007-12-01

    Fluid and melt inclusions are preserved within pegmatite bodies and cumulus minerals within mafic-ultramafic layered intrusions that host economic concentrations of the platinum-group elements (e.g., Bushveld Complex, South Africa; Stillwater Complex, Montana). The inclusions indicate that the earliest volatile phase to have exsolved from the crystallizing intrusions was a relatively anhydrous carbonic fluid (CO2-dominated). As crystallization proceeded, volatiles became increasingly water-rich and saline, consistent with the relative saturation limits of carbonic and aqueous fluids in mafic silicate liquids, and the partitioning behavior of Cl in fluid-melt systems. Previously unreported, the latest stage volatiles in the layered intrusions were halide melts (slightly hydrous molten salts) of relatively simply composition (NaCl with minor KCl or CaCl2) with salinities in excess of 90 wt% eq. NaCl or CaCl2. These volatiles were trapped at minimum temperatures of 760-800°C, near the eutectic temperature for water-saturated granitic liquid at moderate crustal pressures. Trace element analysis of the salt melt inclusions by laser ablation ICP-MS (ETH Zürich) show that they contain no detectable concentrations of ore and accessory metals. This is in contrast to the earlier, lower salinity volatiles which contain ppm-concentrations of Pt, Pd, As, Bi, Sb as well as abundant S and base metals. Heterogeneous entrapment of late-stage silicate melt and halide melt provides unambiguous evidence for the coexistence of both phases. However, experimental constraints on the nature of exsolved volatiles from mafic or felsic silicate liquids suggest that the halide melt phases cannot represent an exsolved phase from that coexisting silicate liquid, since this would require unrealistically high (initial) Cl:H2O ratios for the parental silicate liquid (> 9 for a granitic residue). Analysis of rhyodacitic silicate melt inclusions that coexist with the halide melt inclusions show

  7. A thermodynamic model of nickel smelting and direct high-grade nickel matte smelting processes: Part II. distribution behaviors of Ni, Cu, Co, Fe, As, Sb, and Bi

    NASA Astrophysics Data System (ADS)

    Tan, Pengfu; Neuschütz, Dieter

    2001-04-01

    A thermodynamic model has been developed to predict the distribution behavior of Ni, Cu, Co, Fe, S, As, Sb, and Bi in nickel smelting and direct high-grade nickel matte smelting processes. The model has been validated by numerous experimental data and industrial data with a wide range of operating conditions. The effect of operating conditions on the distributions of Ni, Cu, Co, As, Sb, and Bi among the gas, matte, and slag phases has been investigated. It was found that the distribution behavior of Ni, Co, Cu, As, Sb, and Bi in the nickel smelting furnace depends on process parameters such as the smelting temperature, matte grade, oxygen enrichment, Fe/SiO2 ratio in the slag, Cu/Ni ratio in charge, and oil/air ratio. The parameters also have an influence on the behavior of Fe3O4 in the slag.

  8. Internal switching and backward inhibition in depression and rumination.

    PubMed

    Chen, Xiao; Feng, Zhengzhi; Wang, Tao; Su, Hong; Zhang, Lihong

    2016-09-30

    Prior research has suggested that impairments of switching abilities are associated with depression as well as rumination. Backward inhibition (BI) refers to the ability to inhibit the processing of previously relevant information and is demonstrated to be one of the key mechanisms underlying switching abilities. However, the association between BI in internal switching and depression/rumination remains uninvestigated. To examine this association, a modified Internal Shifting Task (IST) was administered to a sample of dysphoric and healthy control undergraduates. Results showed that depressive symptoms were not associated with difficulties in switching among subjects held in working memory, while trait ruminators performed poorly in switching internally. Surprisingly, no association between BI in internal switching and rumination/depressive symptoms was found. These findings indicate that rumination is characterized by poor performance in internal switching, but this deficit is not associated with BI. PMID:27449002

  9. Calculation of the fractional interstitial component of boron diffusion and segregation coefficient of boron in Si0.8Ge0.2

    NASA Astrophysics Data System (ADS)

    Fang, Tilden T.; Fang, Wingra T. C.; Griffin, Peter B.; Plummer, James D.

    1996-02-01

    Investigation of boron diffusion in strained silicon germanium buried layers reveals a fractional interstitial component of boron diffusion (fBI) in Se0.8Ge0.2 approximately equal to the fBI value in silicon. In conjunction with computer-simulated boron profiles, the results yield an absolute lower-bound of fBI in Si0.8Ge0.2 of ˜0.8. In addition, the experimental methodology provides a unique vehicle for measuring the segregation coefficient; oxidation-enhanced diffusion is used instead of an extended, inert anneal to rapidly diffuse the dopant to equilibrium levels across the interface, allowing the segregation coefficient to be measured more quickly.

  10. An Improved Method to Determine {sup 210}Pb, {sup 210}Bi and {sup 210}Po in air Aerosol Filters

    SciTech Connect

    Miguel, E. G. San; Bolivar, J. P.; Teran, T.

    2008-08-07

    {sup 222}Rn daughters (e.g. {sup 210}Pb, {sup 210}Po, {sup 210}Bi) have been widely used to study a variety of atmospheric processes. Many works in literature about {sup 222}Rn daughters do not specify the way by the activities of these radionuclides are calculated. Besides, {sup 210}Po corrections due to the in-growth of {sup 210}Bi, if taken into account, are not indicated. In this work, the increase in uncertainties of radionuclides activities due to delay between air sampling and radionuclides determinations have been evaluated and the influence of neglecting the contribution of {sup 210}Bi in-growth to {sup 210}Po determination has been estimated. The results indicate that, in general, ignoring the {sup 210}Bi in-growth in {sup 210}Po determinations lead to significant differences (could reach until 100%) between the estimation of {sup 210}Po activity and its true value.

  11. Multi-Bit Nano-Electromechanical Nonvolatile Memory Cells (Zigzag T Cells) for the Suppression of Bit-to-Bit Interference.

    PubMed

    Choi, Woo Young; Han, Jae Hwan; Cha, Tae Min

    2016-05-01

    Multi-bit nano-electromechanical (NEM) nonvolatile memory cells such as T cells were proposed for higher memory density. However, they suffered from bit-to-bit interference (BI). In order to suppress BI without sacrificing cell size, this paper proposes zigzag T cell structures. The BI suppression of the proposed zigzag T cell is verified by finite-element modeling (FEM). Based on the FEM results, the design of zigzag T cells is optimized. PMID:27483893

  12. Temporal and spatial stability in translation invariant linear resistive networks.

    PubMed

    Solak, M K

    1997-01-01

    Simple algebraic methods are proposed to evaluate the temporal and spatial stability of translation invariant linear resistive networks. Temporal stability is discussed for a finite number of nodes n. The proposed method evaluates stability of a Toeplitz pencil A(n)(a)+muB(n)(b) in terms of parameters a(i ) and b(i). In many cases a simple method allows one to verify positive definition of B(n)(b) in terms of b(i) only. PMID:18255673

  13. Three dimensional Dirac semimetals

    NASA Astrophysics Data System (ADS)

    Zaheer, Saad

    We extend the physics of graphene to three dimensional systems by showing that Dirac points can exist on the Fermi surface of realistic materials in three dimensions. Many of the exotic electronic properties of graphene can be ascribed to the pseudorelativistic behavior of its charge carriers due to two dimensional Dirac points on the Fermi surface. We show that certain nonsymmorphic spacegroups exhibit Dirac points among the irreducible representations of the appropriate little group at high symmetry points on the surface of the Brillouin zone. We provide a list of all Brillouin zone momenta in the 230 spacegroups that can host Dirac points. We describe microscopic considerations necessary to design materials in one of the candidate spacegroups such that the Dirac point appears at the Fermi energy without any additional non-Dirac-like Fermi pockets. We use density functional theory based methods to propose six new Dirac semimetals: BiO 2 and SbO2 in the beta-cristobalite lattice (spacegroup 227), and BiCaSiO4, BiMgSiO4, BiAlInO 4, and BiZnSiO4 in the distorted spinels lattice (spacegroup 74). Additionally we derive effective Dirac Hamiltonians given group representative operators as well as tight binding models incorporating spin-orbit coupling. Finally we study the Fermi surface of zincblende (spacegroup 216) HgTe which is effectively point-like at Gamma in the Brillouin zone and exhibits accidental degeneracies along a threefold rotation axis. Whereas compressive strain gaps the band structure into a topological insulator, tensile strain shifts the accidental degeneracies away from Gamma and enlarges the Fermi surface. States on the Fermi surface exhibit nontrivial spin texture marked by winding of spins around the threefold rotation axis and by spin vortices indicating a change in the winding number. This is confirmed by microscopic calculations performed in tensile strained HgTe and Hg0.5Zn 0.5 Te as well as k.p theory. We conclude with a summary of recent

  14. Emission factors and exposures from ground-level pyrotechnics

    NASA Astrophysics Data System (ADS)

    Croteau, Gerry; Dills, Russell; Beaudreau, Marc; Davis, Mac

    Potential exposures from ground-level pyrotechnics were assessed by air monitoring and developing emission factors. Total particulate matter, copper and SO 2 exposures exceeded occupational health guidelines at two outdoor performances using consumer pyrotechnics. Al, Ba, B, Bi, Mg, Sr, Zn, and aldehyde levels were elevated, but did not pose a health hazard based on occupational standards. Emission factors for total particulate matter, metals, inorganic ions, aldehydes, and polyaromatic hydrocarbons (PAHs) were determined for seven ground-supported pyrotechnics through air sampling in an airtight room after combustion. Particle generation ranged from 5 to 13% of the combusted mass. Emission factors (g Kg -1) for metals common to pyrotechnics were also high: K, 23-45; Mg, 1-7; Cu, 0.05-7; and Ba, 0.03-6. Pb emission rates of 1.6 and 2.7% of the combusted mass for two devices were noteworthy. A high correlation ( r2 ≥ 0.89) between metal concentrations in pyrotechnic compositions and emission factors were noted for Pb, Cr, Mg, Sb, and Bi, whereas low correlations ( r2 ≤ 0.1) were observed for Ba, Sr, Fe, and Zn. This may be due to the inherent heterogeneity of multi-effect pyrotechnics. The generation of inorganic nitrogen in both the particulate (NO 2-, NO 3-) and gaseous (NO, NO 2) forms varied widely (<0.1-1000 mg Kg -1). Aldehyde emission factors varied by two orders of magnitude even though the carbon source was carbohydrates and charcoal for all devices: formaldehyde (<7.0-82 mg Kg -1), acetaldehyde (43-210 mg Kg -1), and acrolein (1.9-12 mg Kg -1). Formation of lower molecular weight PAHs such as naphthalene and acenaphthylene were favored, with their emission factors being comparable to that from the combustion of household refuse and agricultural debris. Ba, Sr, Cu, and Pb had emission factors that could produce exposures exceeding occupational exposure guidelines. Sb and unalloyed Mg, which are banned from consumer fireworks in the US, were present in

  15. Studies of flerovium and element 115 homologs with macrocyclic extractants

    NASA Astrophysics Data System (ADS)

    Despotopulos, John Dustin

    Study of the chemistry of the heaviest elements, Z ? 104, poses a unique challenge due to their low production cross-sections and short half-lives. Chemistry also must be studied on the one-atom-at-a-time scale, requiring automated, fast, and very efficient chemical schemes. Recent studies of the chemical behavior of copernicium (Cn, element 112) and flerovium (Fl, element 114) together with the discovery of isotopes of these elements with half-lives suitable for chemical studies have spurred a renewed interest in the development of rapid systems designed to study the chemical properties of elements with Z ≥ 114. This dissertation explores both extraction chromatography and solvent extraction as methods for development of a rapid chemical separation scheme for the homologs of flerovium (Pb, Sn, Hg) and element 115 (Bi, Sb), with the goal of developing a chemical scheme that, in the future, can be applied to on-line chemistry of both Fl and element 115. Macrocyclic extractants, specifically crown ethers and their derivatives, were chosen for these studies. Carrier-free radionuclides, used in these studies, of the homologs of Fl and element 115 were obtained by proton activation of high purity metal foils at the Lawrence Livermore National Laboratory (LLNL) Center for Accelerator Mass Spectrometry (CAMS): natIn(p,n)113Sn, natSn(p,n)124Sb, and Au(p,n)197m,gHg. The carrier-free activity was separated from the foils by novel separation schemes based on ion exchange and extraction chromatography techniques. Carrier-free Pb and Bi isotopes were obtained from development of a novel generator based on cation exchange chromatography using the 232U parent to generate 212Pb and 212Bi. Crown ethers show high selectivity for metal ions based on their size compared to the negatively charged cavity of the ether. Extraction by crown ethers occur based on electrostatic ion-dipole interactions between the negatively charged ring atoms (oxygen, sulfur, etc.) and the positively

  16. Studies of flerovium and element 115 homologs with macrocyclic extractants

    NASA Astrophysics Data System (ADS)

    Despotopulos, John Dustin

    Study of the chemistry of the heaviest elements, Z ? 104, poses a unique challenge due to their low production cross-sections and short half-lives. Chemistry also must be studied on the one-atom-at-a-time scale, requiring automated, fast, and very efficient chemical schemes. Recent studies of the chemical behavior of copernicium (Cn, element 112) and flerovium (Fl, element 114) together with the discovery of isotopes of these elements with half-lives suitable for chemical studies have spurred a renewed interest in the development of rapid systems designed to study the chemical properties of elements with Z ≥ 114. This dissertation explores both extraction chromatography and solvent extraction as methods for development of a rapid chemical separation scheme for the homologs of flerovium (Pb, Sn, Hg) and element 115 (Bi, Sb), with the goal of developing a chemical scheme that, in the future, can be applied to on-line chemistry of both Fl and element 115. Macrocyclic extractants, specifically crown ethers and their derivatives, were chosen for these studies. Carrier-free radionuclides, used in these studies, of the homologs of Fl and element 115 were obtained by proton activation of high purity metal foils at the Lawrence Livermore National Laboratory (LLNL) Center for Accelerator Mass Spectrometry (CAMS): natIn(p,n)113Sn, natSn(p,n)124Sb, and Au(p,n)197m,gHg. The carrier-free activity was separated from the foils by novel separation schemes based on ion exchange and extraction chromatography techniques. Carrier-free Pb and Bi isotopes were obtained from development of a novel generator based on cation exchange chromatography using the 232U parent to generate 212Pb and 212Bi. Crown ethers show high selectivity for metal ions based on their size compared to the negatively charged cavity of the ether. Extraction by crown ethers occur based on electrostatic ion-dipole interactions between the negatively charged ring atoms (oxygen, sulfur, etc.) and the positively

  17. Does Brief Intervention Work For Heavy Episodic Drinking? A Comparison of Emergency Department Patients in Two Cultures

    PubMed Central

    Ye, Yu; Moskalewicz, Jacek; Swiatkiewicz, Grazyna

    2015-01-01

    Little has been reported on the efficacy of brief intervention (BI) among heavy episodic drinkers, although this drinking style is known to be especially harmful in relation to negative consequences including alcohol-related injuries. The comparative efficacy of BI is analyzed in two similar randomized controlled clinical trials of emergency department (ED) patients in two different cultures, both of which exhibit similar drinking styles of heavy episodic drinking: Poland and Mexican-Americans in the U.S. Improvements in drinking and problem outcomes are analyzed at 3-month and 12-month follow-up, using random effects modeling, among 446 Polish patients and 698 Mexican-American patients, randomized to screened only, assessment, and intervention conditions in each study. In Poland significant improvement was observed in all outcome measures for the assessed condition at 3-months compared to baseline, but only in the two problem variables at 12-months, while for the intervention condition, significant improvement was found in all outcome measures at both time periods; however, estimates of the interaction terms were not statistically significant. In the Mexica-American study, while significant improvement in nearly all outcome measures were observed at 3 months and 12 months for both conditions, estimates of the interaction terms suggest that for all drinking variables, but not problem variables, outcomes were significantly improved for the intervention condition over the assessed condition at 12 months, suggesting a 12-month intervention effect. Findings here are non-conclusive regarding a treatment effect of BI for heavy episodic drinking in ED patients. Given the mixed findings for BI in other ED studies, future studies need to explore the efficacy of BI in other populations and cultures exhibiting different drinking patterns to help identify what type of drinker would most benefit from BI in the ED setting. PMID:26688611

  18. Predicted Growth of Two-Dimensional Topological Insulators Consisting of Hydrogenated III-V Thin films on Si(111) Substrate

    NASA Astrophysics Data System (ADS)

    Chuang, Feng-Chuan; Crisostomo, Christian; Yao, Liang-Zi; Yeh, Chun-Chen; Lai, Shu-Ming; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Lin, Hsin; Albao, Marvin; Bansil, Arun

    We have carried out systematic first-principles electronic structure calculations of growth of ultrathin films of compounds of group III (B, Al, In, Ga and Tl) with group V (N, P, As, Sb and Bi) elements on Si(111) substrate, including effects of hydrogenation. A total of six compounds (GaBi, InBi, TlBi, TlAs, TlSb and TlN) are identified to be nontrivial in unhydrogenated case; whereas for hydrogenated case, only four (GaBi, InBi, TlBi and TlSb) remains nontrivial. The band gap is found to be as large as 855 meV for the hydrogenated TlBi film, making this class of III-V materials suitable for room temperature applications. TlBi remains topologically nontrivial with a large band gap at various hydrogen coverages, indicating the robustness of its band topology against bonding effects of substrates. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN and TlBi which can be driven into the nontrivial phase via strain. One and two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates.

  19. Laser-induced oxidation of Zn and Zn alloy films for direct-write grayscale photomasks

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Chang, Marian; Tu, Yuqiang; Poon, David K.; Chapman, Glenn H.; Choo, Chinheng; Peng, Jun

    2006-02-01

    Previous research showed that bimetallic Bi/In and Sn/In films exhibit good grayscale levels after laser exposure due to controlled film oxidation. While giving a large alteration in optical density (OD) from 3.0OD to 0.22OD at 365 nm, Bi/In and Sn/In films show a very nonlinear OD change with laser power, making fine control of grayscale writing difficult at some gray levels. This paper studies Zn and Zn alloy films as possible candidates for improved direct-write grayscale photomask applications. Zn and Zn alloys laser oxidation have been reported previously, but without grayscale optical measurements and applications. In this paper Zn films (50 nm ~ 240 nm), Sn/Zn (100 nm), Al/Zn (100 nm), Bi/Zn (100 nm) and In/Zn (100 nm) were DC- and RF-sputtered onto glass slides and then were scanned by argon ion CW laser (488 nm). Among these films, the highest OD change, 3OD (from 3.2OD before exposure to 0.2OD after laser exposure) at 365 nm, was found in the In/Zn (25/75 nm or 84at% Zn) film. The characterization of grayscale level to laser power modulation in Zn and Zn alloy films with various thickness or composition ratios were investigated. The Zn OD change versus laser power curve is more linear than those of Sn/In and Bi/In films. In/Zn films have better characterization of grayscale level versus laser writing power than pure Zn film. Among these four Zn alloy films, Zn/Al shows most linear relation of OD at 365 nm to laser power modulation.

  20. First Measurement of Several β-Delayed Neutron Emitting Isotopes Beyond N=126.

    PubMed

    Caballero-Folch, R; Domingo-Pardo, C; Agramunt, J; Algora, A; Ameil, F; Arcones, A; Ayyad, Y; Benlliure, J; Borzov, I N; Bowry, M; Calviño, F; Cano-Ott, D; Cortés, G; Davinson, T; Dillmann, I; Estrade, A; Evdokimov, A; Faestermann, T; Farinon, F; Galaviz, D; García, A R; Geissel, H; Gelletly, W; Gernhäuser, R; Gómez-Hornillos, M B; Guerrero, C; Heil, M; Hinke, C; Knöbel, R; Kojouharov, I; Kurcewicz, J; Kurz, N; Litvinov, Yu A; Maier, L; Marganiec, J; Marketin, T; Marta, M; Martínez, T; Martínez-Pinedo, G; Montes, F; Mukha, I; Napoli, D R; Nociforo, C; Paradela, C; Pietri, S; Podolyák, Zs; Prochazka, A; Rice, S; Riego, A; Rubio, B; Schaffner, H; Scheidenberger, Ch; Smith, K; Sokol, E; Steiger, K; Sun, B; Taín, J L; Takechi, M; Testov, D; Weick, H; Wilson, E; Winfield, J S; Wood, R; Woods, P; Yeremin, A

    2016-07-01

    The β-delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with β-decay half-lives for 20 isotopes of Au, Hg, Tl, Pb, and Bi in the mass region N≳126. These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the β-decay strength distribution. This provides important constraints on global theoretical models currently used in r-process nucleosynthesis. PMID:27419564

  1. First Measurement of Several β -Delayed Neutron Emitting Isotopes Beyond N =126

    NASA Astrophysics Data System (ADS)

    Caballero-Folch, R.; Domingo-Pardo, C.; Agramunt, J.; Algora, A.; Ameil, F.; Arcones, A.; Ayyad, Y.; Benlliure, J.; Borzov, I. N.; Bowry, M.; Calviño, F.; Cano-Ott, D.; Cortés, G.; Davinson, T.; Dillmann, I.; Estrade, A.; Evdokimov, A.; Faestermann, T.; Farinon, F.; Galaviz, D.; García, A. R.; Geissel, H.; Gelletly, W.; Gernhäuser, R.; Gómez-Hornillos, M. B.; Guerrero, C.; Heil, M.; Hinke, C.; Knöbel, R.; Kojouharov, I.; Kurcewicz, J.; Kurz, N.; Litvinov, Yu. A.; Maier, L.; Marganiec, J.; Marketin, T.; Marta, M.; Martínez, T.; Martínez-Pinedo, G.; Montes, F.; Mukha, I.; Napoli, D. R.; Nociforo, C.; Paradela, C.; Pietri, S.; Podolyák, Zs.; Prochazka, A.; Rice, S.; Riego, A.; Rubio, B.; Schaffner, H.; Scheidenberger, Ch.; Smith, K.; Sokol, E.; Steiger, K.; Sun, B.; Taín, J. L.; Takechi, M.; Testov, D.; Weick, H.; Wilson, E.; Winfield, J. S.; Wood, R.; Woods, P.; Yeremin, A.

    2016-07-01

    The β -delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with β -decay half-lives for 20 isotopes of Au, Hg, Tl, Pb, and Bi in the mass region N ≳126 . These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the β -decay strength distribution. This provides important constraints on global theoretical models currently used in r -process nucleosynthesis.

  2. Theoretical investigations of optical properties of Ga(In)AsBi quantum well systems using 8-band and 14-band models

    NASA Astrophysics Data System (ADS)

    Gladysiewicz, M.; Ivashev, I.; Wartak, M. S.

    2016-03-01

    We report on possible consequences of alloying of GaAs with GaBi or InBi on band structure and material gain of quantum wells. Typical considered structure consists of 8nm wide GaAsBi quantum well on GaAs substrate. Our analysis is performed using 8-band and 14-band kp models. The obtained results indicate that for GaInAsBi/InP quantum well with 5% of Bi it might be possible to achieve emission wavelengths around 4 μm .

  3. Volatile/mobile trace elements in Karoonda /C4/ chondrite

    NASA Technical Reports Server (NTRS)

    Matza, S. D.; Lipschutz, M. E.

    1977-01-01

    Concentrations of ten volatile/mobile trace elements and of nonvolatile Co in the Karoonda (C4) meteorite were determined, and the atomic abundances relative to C1 are compared with values for the Murchison (C2) and Allende (C3) meteorites. Empirical Bi, In, and Tl data for Karoonda and heated Allende and Murchison are compared with theoretical curves for condensation from a gas of cosmic composition at low pressures. It is suggested that Karoonda might derive from low-temperature open-system metamorphism of pristine C3-like material.

  4. Cs5Sn9(OH)·4NH3

    PubMed Central

    Friedrich, Ute; Korber, Nikolaus

    2014-01-01

    The title compound, penta­caesium nona­stannide hydroxide tetra­ammonia, crystallized from a solution of CsSnBi in liquid ammonia. The Sn9 4− unit forms a monocapped quadratic anti­prism. The hydroxide ion is surrounded by five caesium cations, which form a distorted quadratic pyramidal polyhedron. A three-dimensional network is formed by Cs—Sn [3.8881 (7) Å to 4.5284 (7) Å] and Cs—NH3 [3.276 (7)–3.636 (7) Å] contacts. PMID:24940189

  5. Interaction of High-Energy Proton Beam with a Thin Target and Multiplicities of Neutron

    SciTech Connect

    Demirkol, I.; Tatar, M.; Safak, M. S.; Arasoglu, A.; Tel, E.

    2007-04-23

    An important ingredient in the performance of accelerator driven systems for energy production, waste transmutation and other applications are the number of spallation neutrons produced per incident proton. The neutron multiplicities, angular and energy distributions are usually calculated using simulation codes. We have presented multiplicities of the neutrons emitted in the interaction of a high-energy proton (1500 MeV) with a thin target Pb, Bi. In this study we have used the code ISABEL to calculate multiplicities of the neutron emitted. The results obtained have been compared with the available data.

  6. Combinatorial pulsed laser deposition of doped yttrium iron garnet films on yttrium aluminium garnet

    SciTech Connect

    Sposito, A. Eason, R. W.; Gregory, S. A.; Groot, P. A. J. de

    2014-02-07

    We investigate the crystalline growth of yttrium iron garnet (YIG) films doped with bismuth (Bi) and cerium (Ce) by combinatorial pulsed laser deposition, co-ablating a YIG target and either a Bi{sub 2}O{sub 3} or a CeO{sub 2} target, for applications in microwave and optical communications. Substrate temperature is critical for crystalline growth of YIG with simultaneous inclusion of Bi in the garnet lattice, whereas Ce is not incorporated in the garnet structure, but forms a separate CeO{sub 2} phase.

  7. Concentrations of /sup 207/Bi and /sup 210/Pb-/sup 210/Bi-/sup 210/Po disequilibrium in fish

    SciTech Connect

    Noshkin, V.E.; Wong, K.M.; Eagle, R.J.; Jokela, T.A.

    1984-10-01

    Radioactive /sup 207/Bi, produced during nuclear testing at the Pacific Proving Grounds, concentrates in the muscle tissue and organs of goatfish and certain pelagic lagoon fish from Bikini and Enewetak Atolls. It is reasonable to expect that fish capable of accumulating /sup 207/Bi could also be efficient accumulators of other bismuth isotopes - namely /sup 210/Bi, the daughter of naturally occurring /sup 210/Pb. Therefore, /sup 210/Bi and consequently /sup 210/Po, the decay product of /sup 210/Bi, would be expected in notable excess over the precursor /sup 210/Pb in specific tissues. To test this assumption, we compared concentrations of /sup 210/Pb, /sup 210/Bi, and /sup 210/Po in muscle, liver, and bone separated from some reef species from the Marshall Islands. Concentrations of /sup 210/Bi in muscle and liver were found to exceed those of its precursor by factors of 2 to 15. The excess /sup 210/Bi in some species, however, is not from the environmental sources (either food or water) from which /sup 207/Bi is derived. The data suggest that the excess /sup 210/Bi may be translocated to muscle and liver tissue following the decay of /sup 210/Pb in bone.

  8. Automotive hexband antenna for AM/FM/GPS/SDARS and AMPS/PCS1900 cell phone in an only 65 mm high housing

    NASA Astrophysics Data System (ADS)

    Kammerer, J.; Reiter, L.; Lindenmeier, S.

    2013-04-01

    Nowadays cars are equipped frequently with typical 400 mm long active AM/FM antennas mounted on top close to the rear windshield. In [1], we presented a novel capacitive coupled helical antenna with a height of only 140 mm which performs equivalent to such an 400 mm long antenna. In the next step the antenna height has been reduced to only 56 mm in order to be placed in a low 65 mm housing in combination with other decoupled antennas. The measured results for AM/FM are close to the performance of a whip antenna of 900 mm length. The GPS and SDARS antennas are realized in a combination of two table-formed ring structures with a maximum gain for LHCP at 2339 MHz with 2.9 dBi in zenith and with 5.2 dBi in zenith for RHCP at 1575 MHz with GPS. The VSWR of the cell phone antenna is below 3 for AMPS and PCS1900.

  9. A thermodynamic model of nickel smelting and direct high-grade nickel matte smelting processes: Part I. Model development and validation

    NASA Astrophysics Data System (ADS)

    Tan, Pengfu; Neuschütz, Dieter

    2001-04-01

    A thermodynamic model has been developed to predict the distribution behavior of Ni, Cu, Co, Fe, S, As, Sb, and Bi in the Outokumpu flash-smelting process, the Outokumpu direct high-grade matte smelting process, and the INCO flash-smelting process. In this model, as many as 16 elements (Ni, Cu, Co, Fe, As, Sb, Bi, S, O, Al, Ca, Mg, Si, N, C, and H) are considered, and two nickel sulfide species are used to allow for modeling of sulfur-deficient mattes. The compositions of the matte, slag, and gaseous phases in equilibrium are calculated using Gibbs free energies of formation and the activity coefficients of the components derived from the experimental data. The model predictions are compared with the known industrial data from the Kalgoorlie Nickel Smelter (Kalgoorlie, Australia), the Outokumpu Harjavalta Nickel Smelter (Harjavalta, Finland), the INCO Metals Company (Sudbury, Canada), and from a number of experimental data. An excellent agreement is obtained. It was found that the distribution behaviors of Ni, Co, Cu, Fe, S, As, Sb, and Bi in the nickel smelting furnace depend on process parameters such as the smelting temperature, matte grade, and partial pressure of oxygen in the process.

  10. Robust Large Gap Two-Dimensional Topological Insulators in Hydrogenated III-V Buckled Honeycombs.

    PubMed

    Crisostomo, Christian P; Yao, Liang-Zi; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Albao, Marvin A; Bansil, Arun

    2015-10-14

    A large gap two-dimensional (2D) topological insulator (TI), also known as a quantum spin Hall (QSH) insulator, is highly desirable for low-power-consuming electronic devices owing to its spin-polarized backscattering-free edge conducting channels. Although many freestanding films have been predicted to harbor the QSH phase, band topology of a film can be modified substantially when it is placed or grown on a substrate, making the materials realization of a 2D TI challenging. Here we report a first-principles study of possible QSH phases in 75 binary combinations of group III (B, Al, Ga, In, and Tl) and group V (N, P, As, Sb, and Bi) elements in the 2D buckled honeycomb structure, including hydrogenation on one or both sides of the films to simulate substrate effects. A total of six compounds (GaBi, InBi, TlBi, TlAs, TlSb, and TlN) are identified to be nontrivial in unhydrogenated case; whereas for hydrogenated case, only four (GaBi, InBi, TlBi, and TlSb) remains nontrivial. The band gap is found to be as large as 855 meV for the hydrogenated TlBi film, making this class of III-V materials suitable for room temperature applications. TlBi remains topologically nontrivial with a large band gap at various hydrogen coverages, indicating the robustness of its band topology against bonding effects of substrates. PMID:26390082

  11. Prediction of Large-Gap Two-Dimensional Topological Insulators Consisting of Hydrogenated Bilayers of Group III Elements with Bi

    NASA Astrophysics Data System (ADS)

    Crisostomo, Christian P.; Yao, Liang-Zi; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Albao, Marvin A.; Bansil, Arun

    2015-03-01

    We use first-principles electronic structure calculations to predict a new class of two-dimensional (2D) topological insulators (TIs) in hydrogenated binary compositions of group III elements (B, Al, Ga, In, and Tl) and bismuth (Bi). We identify band inversions in unhydrogenated pristine GaBi, InBi, and TlBi bilayers, with gaps as large as 556 meV for the TlBi case, making these materials suitable for room-temperature applications. Double-sided hydrogenation in which hydrogen was added on opposite sides also exhibited band inversions in the case of GaBi, InBi, and TlBi just as in the unhydrogenated pristine ones. Furthermore, we report the gap to be 885 meV for the hydrogenated TlBi case. Hydrogenation enhace the band gap without changing the band topology. Moreover, our study also aim to demonstrate the possibility of strain engineering in that the topological phase transition in systems whose phase was nontrivial could be driven by suitable strain. Finally, the effect of placing hydrogen to topological edges was also demonstrated. Our findings suggest that the buckled honeycomb structure is a versatile platform for hosting nontrivial topological states and spin-polarized Dirac fermions with the flexibility of chemical and mechanical tunability. The robustness of III-Bi upon hydrogenation shows that these materials are possible to synthesize by growing on substrates.

  12. Bioelectrical impedance changes in regional extracellular fluid alterations.

    PubMed

    Kim, C T; Findley, T W; Reisman, S R

    1997-08-01

    The purpose of this study was to determine whether changes in bioelectrical impedance (BI) can reveal regional extracellular fluid (ECF) alterations. ECF changes were induced by holding various arm positions for ten minutes, and they were evaluated through the measurement of BI in eight normal adult subjects. A low frequency current (100 Hz, 0.50 mA) was applied using an electromyography machine through two current electrodes, and the voltage signals were recorded by two amplitude electrodes. The corresponding BI was calculated by Ohm's law, resistance = voltage/current (R = V/I). There was no significant difference between BI and time interval, but between BI and arm position (two-way ANOVA with replicate, p = 0.954, p < 0.001). BI has a negative correlation with wrist circumference. These results show that this experimental method can be used as reflection of ECF changes and that both position and wrist circumference are major factors for BI in the upper extremity. PMID:9298342

  13. Anxiety-related behavioral inhibition in rats: a model to examine mechanisms underlying the risk to develop stress-related psychopathology.

    PubMed

    Qi, C; Roseboom, P H; Nanda, S A; Lane, J C; Speers, J M; Kalin, N H

    2010-11-01

    Behavioral inhibition (BI) is an adaptive defensive response to threat; however, children who display extreme BI as a stable trait are at risk for development of anxiety disorders and depression. The present study validates a rodent model of BI based on an ethologically relevant predator exposure paradigm. We show that individual differences in rat BI are stable and trait-like from adolescence into adulthood. Using in situ hybridization to quantify expression of the immediate early genes homer1a and fos as measures of neuronal activation, we show that individual differences in BI are correlated with the activation of various stress-responsive brain regions that include the paraventricular nucleus of the hypothalamus and CA3 region of the hippocampus. Further supporting the concept that threat-induced BI in rodents reflects levels of anxiety, we also show that BI is decreased by administration of the anxiolytic, diazepam. Finally, we developed criteria for identifying extreme BI animals that are stable in their expression of high levels of BI and also show that high BI (HBI) individuals exhibit maladaptive appetitive responses following stress exposure. These findings support the use of predator threat as a stimulus and HBI rats as a model to study mechanisms underlying extreme and stable BI in humans. PMID:20738409

  14. Temperament and Parenting Styles in Early Childhood Differentially Influence Neural Response to Peer Evaluation in Adolescence

    PubMed Central

    Guyer, Amanda E.; Jarcho, Johanna M.; Pérez-Edgar, Koraly; Degnan, Kathryn A.; Pine, Daniel S.; Fox, Nathan A.; Nelson, Eric E.

    2015-01-01

    Behavioral inhibition (BI) is a temperament characterized by social reticence and withdrawal from unfamiliar or novel contexts and conveys risk for social anxiety disorder. Developmental outcomes associated with this temperament can be influenced by children’s caregiving context. The convergence of a child’s temperamental disposition and rearing environment is ultimately expressed at both the behavioral and neural levels in emotional and cognitive response patterns to social challenges. The present study used functional neuroimaging to assess the moderating effects of different parenting styles on neural response to peer rejection in two groups of adolescents characterized by their early childhood temperament (Mage = 17.89 years, N= 39, 17 males, 22 females; 18 with BI; 21 without BI). The moderating effects of authoritarian and authoritative parenting styles were examined in three brain regions linked with social anxiety: ventrolateral prefrontal cortex (vlPFC), striatum, and amygdala. In youth characterized with BI in childhood, but not in those without BI, diminished responses to peer rejection in vlPFC were associated with higher levels of authoritarian parenting. In contrast, all youth showed decreased caudate response to peer rejection at higher levels of authoritative parenting. These findings indicate that BI in early life relates to greater neurobiological sensitivity to variance in parenting styles, particularly harsh parenting, in late adolescence. These results are discussed in relation to biopsychosocial models of development. PMID:25588884

  15. Increased bismuth concentration in MBE GaAs{sub 1−x}Bi{sub x} films by oscillating III/V flux ratio during growth

    SciTech Connect

    Wood, Adam W. Babcock, Susan E.; Li, Jincheng; Brown, April S.

    2015-05-15

    The authors have examined bismuth concentration profiles in GaAs{sub 1−x}Bi{sub x} films grown by molecular beam epitaxy using high angle annular dark field imaging (Z-contrast imaging) in an aberration-corrected scanning transmission electron microscope in conjunction with x-ray diffraction. Samples were grown with a gradient in each of the component fluxes, and therefore, the III/V ratio across the substrate. Rotating the sample during growth exposed the growth surface to an oscillating III/V flux ratio. Sinusoidal [Bi] profiles resulted in the growth direction, the wavelength and number of which were consistent with the growth rate and the rate of substrate rotation. However, the magnitude of [Bi] in the observed fluctuations was greater than the maximum [Bi] achieved using the same Bi flux and Ga/As flux ratios in steady-state conditions on a stationary substrate, suggesting that varying the III/V flux ratio during growth promotes the incorporation of Bi in GaAs{sub 1−x}Bi{sub x} films. A proposed qualitative model for how this enhancement might occur hypothesizes a critical role for alternating growth and shrinkage of Ga-Bi predroplet clusters on the surface as the growing material is rotated through Ga-rich and As-rich flux compositions.

  16. Effect of zinc on the solubility and distribution coefficients of bismuth in indium antimonide

    SciTech Connect

    Ufimtsev, V.B.; Lapkina, I.A.; Zinov'ev, V.G.; Sorokina, O.V.

    1988-04-01

    In the preparation of solid structures of InSb with Bi and Zn, it is necessary to have information on the boundaries of the regions of homogeneity of solid solutions of bismuth and zinc in indium antimonide; for determining these regions along sections of the In-Sb-Bi-Zn quaternary system: InSb-Bi-Zn, InSb-InBi-Zn, InSb-In/sub 2/Bi-Zn, InSb-InBi-Zn/sub 3/Sb/sub 2/, InSb-In/sub 2/Bi-Zn/sub 3/Sb/sub 2/, melts of a certain composition along the direction of the rays with a ratio of Bi (InBi, In/sub 2/Bi) to Zn or Zn/sub 3/Sb/sub 2/ equal to 1:3, 1:1, 3:1 were synthesized. The melts were annealed for 300 h at 400/degree/C, cooled from this temperature in water, and studied by methods of metallographic and local x-ray spectral analysis. The study of the combined solubility of Bi and Zn in InSb thus showed that it increases significantly in comparison to the corresponding ternary systems and is a function of the section of the In-Sb-Bi-Zn quaternary system in which the indium antimonide is doped with bismuth and zinc.

  17. Temperament and Parenting Styles in Early Childhood Differentially Influence Neural Response to Peer Evaluation in Adolescence.

    PubMed

    Guyer, Amanda E; Jarcho, Johanna M; Pérez-Edgar, Koraly; Degnan, Kathryn A; Pine, Daniel S; Fox, Nathan A; Nelson, Eric E

    2015-07-01

    Behavioral inhibition (BI) is a temperament characterized by social reticence and withdrawal from unfamiliar or novel contexts and conveys risk for social anxiety disorder. Developmental outcomes associated with this temperament can be influenced by children's caregiving context. The convergence of a child's temperamental disposition and rearing environment is ultimately expressed at both the behavioral and neural levels in emotional and cognitive response patterns to social challenges. The present study used functional neuroimaging to assess the moderating effects of different parenting styles on neural response to peer rejection in two groups of adolescents characterized by their early childhood temperament (M(age) = 17.89 years, N = 39, 17 males, 22 females; 18 with BI; 21 without BI). The moderating effects of authoritarian and authoritative parenting styles were examined in three brain regions linked with social anxiety: ventrolateral prefrontal cortex (vlPFC), striatum, and amygdala. In youth characterized with BI in childhood, but not in those without BI, diminished responses to peer rejection in vlPFC were associated with higher levels of authoritarian parenting. In contrast, all youth showed decreased caudate response to peer rejection at higher levels of authoritative parenting. These findings indicate that BI in early life relates to greater neurobiological sensitivity to variance in parenting styles, particularly harsh parenting, in late adolescence. These results are discussed in relation to biopsychosocial models of development. PMID:25588884

  18. Liquid structure and temperature invariance of sound velocity in supercooled Bi melt

    SciTech Connect

    Emuna, M.; Mayo, M.; Makov, G.; Greenberg, Y.; Caspi, E. N.; Yahel, E.; Beuneu, B.

    2014-03-07

    Structural rearrangement of liquid Bi in the vicinity of the melting point has been proposed due to the unique temperature invariant sound velocity observed above the melting temperature, the low symmetry of Bi in the solid phase and the necessity of overheating to achieve supercooling. The existence of this structural rearrangement is examined by measurements on supercooled Bi. The sound velocity of liquid Bi was measured into the supercooled region to high accuracy and it was found to be invariant over a temperature range of ∼60°, from 35° above the melting point to ∼25° into the supercooled region. The structural origin of this phenomenon was explored by neutron diffraction structural measurements in the supercooled temperature range. These measurements indicate a continuous modification of the short range order in the melt. The structure of the liquid is analyzed within a quasi-crystalline model and is found to evolve continuously, similar to other known liquid pnictide systems. The results are discussed in the context of two competing hypotheses proposed to explain properties of liquid Bi near the melting: (i) liquid bismuth undergoes a structural rearrangement slightly above melting and (ii) liquid Bi exhibits a broad maximum in the sound velocity located incidentally at the melting temperature.

  19. Is obesity contagious by way of body image? A study on Japanese female students in the United States.

    PubMed

    Bagrowicz, Rinako; Watanabe, Chiho; Umezaki, Masahiro

    2013-10-01

    Although it has been suggested that obesity is 'contagious' within the social network, direct cause of this spread of obesity remains unclear. This study hypothesized that Body Image (BI), the perception of one's own body size, may play a role in this obesity spread, since a high prevalence of obesity could shift people's perception of 'what is normal'. Young Japanese females (n = 53) were interviewed within 1 month after moving to New York City, where the prevalence of obesity is substantially higher than that of their home country, Japan. Each participant was examined for her BI in terms of current body size (CBS) and ideal body size (IBS). They were interviewed again 2 months after the first examination. Between the two interviews, the participants' CBS was decreased (having thinner self-image), while the IBS increased (having fatter ideal-image), leading to less dissatisfaction (smaller CBS-IBS) with their body size. These results suggest that one's BI could change in a period as short as 2 months, possibly because of being surrounded by more obese people. The IBS change was positively associated with BMI change (increased by 0.4 ± 0.6 kg/m²), warranting further study on the role of BI in the spread of obesity. PMID:23564365

  20. Microstructural behavior of iron and bismuth added Sn-1Ag-Cu solder under elevated temperature aging

    NASA Astrophysics Data System (ADS)

    Ali, Bakhtiar; Sabri, Mohd Faizul Mohd; Jauhari, Iswadi

    2016-07-01

    An extensive study was done to investigate the microstructural behavior of iron (Fe) and bismuth (Bi) added Sn-1Ag-0.5Cu (SAC105) under severe thermal aging conditions. The isothermal aging was done at 200 °C for 100 h, 200 h, and 300 h. Optical microscopy with cross-polarized light revealed that the grain size significantly reduces with Fe/Bi addition to the base alloy SAC105 and remains literally the same after thermal aging. The micrographs of field emission scanning electron microscopy (FESEM) with backscattered electron detector and their further analysis via imageJ software indicated that Fe/Bi added SAC105 showed a significant reduction in the IMCs size (Ag3Sn and Cu6Sn5), especially the Cu6Sn5 IMCs, as well as β-Sn matrix and a refinement in the microstructure, which is due to the presence of Bi in the alloys. Moreover, their microstructure remains much more stable under severe thermal aging conditions, which is because of the presence of both Fe and Bi in the alloy. The microstructural behavior suggests that Fe/Bi modified SAC105 would have much improved reliability under severe thermal environments. These modified alloys also have relatively low melting temperature and low cost.

  1. Development of Bismuth-based Lead-free Piezoelectric Materials: Thin Film Piezoelectric Materials via PVD and CSD Routes

    NASA Astrophysics Data System (ADS)

    Jeon, Yu Hong

    Piezoelectric materials have been widely used in electromechanical actuators, sensors, and ultrasonic transducers. Among these materials, lead zirconate titanate Pb(Zr1-xTix)O3 (PZT) has been primarily investigated due to its excellent piezoelectric properties. However, environmental concerns due to the toxicity of PbO have led to investigations into alternative materials systems. Bismuth-based perovskite piezoelectric materials such as (Bi0.5,Na0.5)TiO3 - (Bi0.5K 0.5)TiO3 (BNT - BKT), (Bi0.5,Na0.5 )TiO3 - (Bi0.5K0.5)TiO3 - BaTiO3(BNT - BKT - BT), (Bi0.5K 0.5)TiO3 - Bi(Zn0.5,Ti0.5)O 3 (BKT - BZT), and (Bi0.5,Na0.5)TiO 3 - (Bi0.5K0.5)TiO3 - Bi(Mg 0.5,Ti0.5)O3 (BNT - BKT - BMgT) have been explored as potential alternatives to PZT. These materials systems have been extensively studied in bulk ceramic form, however many of the ultimate applications will be in thin film embodiments (i.e., microelectromechanical systems). For this reason, in this thesis these lead-free piezoelectrics are synthesized in thin film form to understand the structure-property-processing relationships and their impact on the ultimate device response. Fabrication of high quality of 0.95BKT - 0.05BZT thin films on platinized silicon substrates was attempted by pulsed laser deposition. Due to cation volatility, deposition parameters such as substrate temperature, deposition pressure, and target-substrate distance, as well as target overdoping were explored to achieve phase pure materials. This route led to high dielectric loss, indicative of poor ferroelectric behavior. This was likely a result of the poor thin film morphology observed in films deposited via this method. Subsequently, 0.8BNT - 0.2BKT, 85BNT - 10BKT - 5BT, and 72.5BNT - 22.5BKT - 5BMgT (near morphotropic phase boundary composition) were synthesized via chemical solution deposition. To compensate the loss of A-site cations, overdoped precursor solutions were prepared. Crystallization after each spin cast layer were required to

  2. Measuring the activity of inhaled ²²²Rn using a lung counting system.

    PubMed

    Zhiwei, Cheng; Mingyan, Jia; Maoquan, Shen

    2015-02-01

    A new method of directly measuring (222)Rn progeny in a worker's lung using a lung counting system is introduced. To determine the efficiency of the lung counting system, a torso phantom manufactured by the China Institute for Radiation Protection was used, where activated carbon that had been loaded in a radon chamber with a defined quantity of radon represented the lungs, which were usually made of urethane foam. The minimum detectable activity (MDA) of (214)Bi, one of the (222)Rn progenies, was estimated to be 7.3 Bq for a measurement time of 4000 s. Based on the time (222)Rn progenies stay in the lung, it may be concluded that the lung counting system described can be well used for directly measuring the activity of (214)Bi in the lung short time after a worker inhaled (222)Rn at his/her workplace. PMID:24803514

  3. Bismuth-indium two-dimensional compounds on Si(111) surface

    NASA Astrophysics Data System (ADS)

    Denisov, N. V.; Alekseev, A. A.; Utas, O. A.; Azatyan, S. G.; Zotov, A. V.; Saranin, A. A.

    2016-09-01

    Using scanning tunneling microscopy (STM) observations, it has been found that codeposition of Bi and In onto Si(111)7 × 7 surface, followed by 250-550 °C annealing, induces formation of a set of the ordered (Bi, In)/Si(111) stable structures, including 2 √ 3 × 3, 5 × 5, √ 7 × √ 7 and 2 × 2. Under appropriate conditions, the structures can occupy almost the entire surface, except for 2 √ 3 × 3 which is formed only locally. Scanning tunneling spectroscopy has demonstrated that the 5 × 5 and √ 7 × √ 7 structures are semiconducting, while the 2 × 2 is metallic. The 5 × 5, √ 7 × √ 7, and 2 × 2 structural models have been proposed on the basis of DFT calculations and comparison of simulated and experimental STM images.

  4. Orientational bond and Néel order in the two-dimensional ionic Hubbard model

    NASA Astrophysics Data System (ADS)

    Hafez-Torbati, Mohsen; Uhrig, Götz S.

    2016-05-01

    Unconventional phases often occur where two competing mechanisms compensate. An excellent example is the ionic Hubbard model where the alternating local potential δ , favoring a band insulator (BI), competes with the local repulsion U , favoring a Mott insulator (MI). By continuous unitary transformations we derive effective models in which we study the softening of various excitons. The softening signals the instability towards new phases that we describe on the mean-field level. On increasing U from the BI in two dimensions, we find a bond-ordered phase breaking orientational symmetry due to a d -wave component. Then, antiferromagnetic order appears coexisting with the d -wave bond order. Finally, the d -wave order vanishes and a Néel-type MI persists.

  5. Engineering a topological phase transition in β-InSe via strain

    NASA Astrophysics Data System (ADS)

    Ma, Yandong; Dai, Ying; Yu, Lin; Niu, Chengwang; Huang, Baibiao

    2013-07-01

    We report that β-InSe endowed with external strain realizes a novel three dimensional topological insulator (TI) by ab initio calculations. We predicate that the promising topological non-trivial state can be observed in an accessible temperature regime in β-InSe for its large spin-orbital band gap up to 121 meV. Specifically, unlike in previous literature where the band inversion (BI) in TIs is induced using heavy elements that have strong spin-orbital coupling (SOC), we provide a remarkable blueprint for stabilizing BI solely by mechanical deformation so that β-InSe could display BI even without considering SOC. Nevertheless, SOC is still needed to create a band gap at the crossing point by breaking the incompatibility symmetry of the inverted bands.

  6. Impact of behavioral inhibition and parenting style on internalizing and externalizing problems from early childhood through adolescence.

    PubMed

    Williams, Lela Rankin; Degnan, Kathryn A; Perez-Edgar, Koraly E; Henderson, Heather A; Rubin, Kenneth H; Pine, Daniel S; Steinberg, Laurence; Fox, Nathan A

    2009-11-01

    Behavioral inhibition (BI) is characterized by a pattern of extreme social reticence, risk for internalizing behavior problems, and possible protection against externalizing behavior problems. Parenting style may also contribute to these associations between BI and behavior problems (BP). A sample of 113 children was assessed for BI in the laboratory at 14 and 24 months of age, self-report of maternal parenting style at 7 years of age, and maternal report of child internalizing and externalizing BP at 4, 7, and 15 years. Internalizing problems at age 4 were greatest among behaviorally inhibited children who also were exposed to permissive parenting. Furthermore, greater authoritative parenting was associated with less of an increase in internalizing behavior problems over time and greater authoritarian parenting was associated with a steeper decline in externalizing problems. Results highlight the importance of considering child and environmental factors in longitudinal patterns of BP across childhood and adolescence. PMID:19521761

  7. Method for radioactivity monitoring

    DOEpatents

    Umbarger, C. John; Cowder, Leo R.

    1976-10-26

    The disclosure relates to a method for analyzing uranium and/or thorium contents of liquid effluents preferably utilizing a sample containing counting chamber. Basically, 185.7-keV gamma rays following .sup.235 U alpha decay to .sup.231 Th which indicate .sup.235 U content and a 63-keV gamma ray doublet found in the nucleus of .sup.234 Pa, a granddaughter of .sup.238 U, are monitored and the ratio thereof taken to derive uranium content and isotopic enrichment .sup.235 U/.sup.235 U + .sup.238 U) in the liquid effluent. Thorium content is determined by monitoring the intensity of 238-keV gamma rays from the nucleus of .sup.212 Bi in the decay chain of .sup.232 Th.

  8. Aliovalent cation ordering, coexisting ferroelectric structures, and electric field induced phase transformation in lead-free ferroelectric Na0.5Bi0.5TiO3

    NASA Astrophysics Data System (ADS)

    Pan, Jaysree; Niranjan, Manish K.; Waghmare, Umesh V.

    2016-03-01

    Using first-principles calculations, we show that a specific chemical ordering of Na and Bi in Na0.5Bi0.5TiO3 is responsible for the co-existence of its ferroelectric phases with rhombohedral R3c and monoclinic Cc structures, which are relevant to its morphotropic phase boundary and large piezoelectric response. We identify the signatures of chemical ordering in the calculated phonon spectra and establish the prevalence of A-type ordering through comparison with experiment. We uncover a mechanism of the observed electric field induced Cc to lower energy R3c structural transformation promoted by a hybrid soft mode involving a combination of TiO6 rotations and a polar component.

  9. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    NASA Astrophysics Data System (ADS)

    Cui, J.; Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J.; Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D.; Marinescu, M.; Huang, Q. Z.; Wu, H.; Vuong, N. V.; Liu, J. P.

    2014-05-01

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μB at 50 K and 300 K, respectively.

  10. Impact of Behavioral Inhibition and Parenting Style on Internalizing and Externalizing Problems from Early Childhood through Adolescence

    PubMed Central

    Williams, Lela Rankin; Perez-Edgar, Koraly E.; Henderson, Heather A.; Rubin, Kenneth H.; Pine, Daniel S.; Steinberg, Laurence; Fox, Nathan A.

    2009-01-01

    Behavioral inhibition (BI) is characterized by a pattern of extreme social reticence, risk for internalizing behavior problems, and possible protection against externalizing behavior problems. Parenting style may also contribute to these associations between BI and behavior problems (BP). A sample of 113 children was assessed for BI in the laboratory at 14 and 24 months of age, self-report of maternal parenting style at 7 years of age, and maternal report of child internalizing and externalizing BP at 4, 7, and 15 years. Internalizing problems at age 4 were greatest among behaviorally inhibited children who also were exposed to permissive parenting. Furthermore, greater authoritative parenting was associated with less of an increase in internalizing behavior problems over time and greater authoritarian parenting was associated with a steeper decline in externalizing problems. Results highlight the importance of considering child and environmental factors in longitudinal patterns of BP across childhood and adolescence. PMID:19521761

  11. Atomic-level structural and chemical analysis of Cr-doped Bi2Se3 thin films

    PubMed Central

    Ghasemi, A.; Kepaptsoglou, D.; Collins-McIntyre, L. J.; Ramasse, Q.; Hesjedal, T.; Lazarov, V. K.

    2016-01-01

    We present a study of the structure and chemical composition of the Cr-doped 3D topological insulator Bi2Se3. Single-crystalline thin films were grown by molecular beam epitaxy on Al2O3 (0001), and their structural and chemical properties determined on an atomic level by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A regular quintuple layer stacking of the Bi2Se3 film is found, with the exception of the first several atomic layers in the initial growth. The spectroscopy data gives direct evidence that Cr is preferentially substituting for Bi in the Bi2Se3 host. We also show that Cr has a tendency to segregate at internal grain boundaries of the Bi2Se3 film. PMID:27221782

  12. 212Bi-DOTMP: an alpha particle emitting bone-seeking agent for targeted radiotherapy.

    PubMed

    Hassfjell, S P; Bruland, O S; Hoff, P

    1997-04-01

    The synthesis and in vivo stability of the bone-seeking alpha-particle emitting compounds 212Bi-DOTMP and 212Pb/212Bi-DOTMP are described. 212Bi-DOTMP, injected i.v. into Balb/c mice, showed prominent bone localization and a rapid clearance from blood and other organs. Femur/blood ratios increased from 13 at 15 min up to 490 at 2.0 h postinjection. Enhanced uptake of 212Bi-DOTMP was demonstrated in regions with high bone turnover. A comparison between 212Bi-DOTMP and [153Sm]Sm-EDTMP showed essentially no differences in biodistribution. 212Pb/212Bi-DOTMP followed a similar biodistribution, except for slightly elevated levels of 212Bi in the kidneys. The present study has shown 212Bi-DOTMP to be an in vivo stable bone-seeking radiopharmaceutical with promising biological properties for the treatment of sclerotic metastases and osteoblastic osteosarcoma. PMID:9228657

  13. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    SciTech Connect

    Cui, J. Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J.; Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D.; Marinescu, M.; Huang, Q. Z.; Wu, H.; Vuong, N. V.; Liu, J. P.

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μ{sub B} at 50 K and 300 K, respectively.

  14. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    SciTech Connect

    Cui, J.; Choi, J. P.; Li, G.; Polikarpov, E.; Darsell, J.; Kramer, M. J.; Zarkevich, N. A.; Wang, L. L.; Johnson, D. D.; Marinescu, M.; Huang, Q. Z.; Wu, H.; Vuong, N. V.; Liu, J. P.

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μB at 50 K and 300 K, respectively.

  15. Prediction of Quantum Anomalous Hall Insulator in Functionalized GaBi Honeycomb

    NASA Astrophysics Data System (ADS)

    Crisostomo, Christian; Chen, Sung-Ping; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    Using first-principles electronic calculations, we predict functionalized GaBi honeycomb under tensile strain to harbor quantum anomalous hall (QAH) insulating phase. A single band inversion at Γ point was found in spin-polarized band structure of half-fluorinated planar strained GaBi. In order to confirm the topological properties, we evaluated the Chern number (C) and found that C = 1, indicating the presence of QAH phase. Additionally, the same value was also obtained by using hydrogen atoms, instead of fluorine atoms, as the adsorbate in both planar and buckled GaBi. Moreover, the electronic spectrum of a half-fluorinated GaBi nanoribbon with armchair or zigzag edges possess only one edge band crossing the Fermi level within the band gap. Finally, a suitable substrate which could induce the similar effect of half-hydrogenation or half-fluorination on the GaBi honeycomb could be used for spintronic devices.

  16. First-principles study of the surface energy and work function of III-V semiconductor compounds

    NASA Astrophysics Data System (ADS)

    Liu, W.; Zheng, W. T.; Jiang, Q.

    2007-06-01

    Surface energy and work function of 12 III-V semiconductors, AlP, AlAs, AlSb, AlBi, GaP, GaAs, GaSb, GaBi, InP, InAs, InSb, and InBi, on (110) surfaces are calculated using ab initio density functional theory. The obtained values are proportional to the corresponding cohesive energy and are in good agreement with available experimental data and theoretical models. The linear relationship among cohesive energy, surface energy, and work function is interpreted by analyzing their electronic properties where four (110) surfaces of Al series semiconductors, AlP, AlAs, AlSb, and AlBi, are taken as examples.

  17. Training the biomedical informatics workforce in Latin America: results of a needs assessment

    PubMed Central

    Blas, Magaly M; Curioso, Walter H; Zimic, Mirko; Carcamo, Cesar P; Castagnetto, Jesus M; Lescano, Andres G; Lopez, Diego M

    2011-01-01

    Objective To report the results of a needs assessment of research and training in Medical Informatics (MI) and Bioinformatics (BI) in Latin America. Methods and results This assessment was conducted by QUIPU: The Andean Global Health Informatics Research and Training Center. After sending email invitations to MI–BI related professionals from Latin America, 142 surveys were received from 11 Latin American countries. The following were the top four ranked MI-related courses that a training programme should include: introduction to biomedical informatics; data representation and databases; mobile health; and courses that address issues of security, confidentiality and privacy. Several new courses and topics for research were suggested by survey participants. The information collected is guiding the development of curricula and a research agenda for the MI and BI QUIPU multidisciplinary programme for the Andean Region and Latin America. PMID:22080537

  18. The BiPo low-background detector project

    NASA Astrophysics Data System (ADS)

    Vasilyev, R. V.

    2009-05-01

    A low-background detector designed to search for weak radioactive pollution by 208Tl and 214Bi in thin samples of a large area is described. The samples are 12-m2 source foils made of 82Se or 150Nd enriched isotopes. Such samples are planned for use in investigating neutrinoless double β decay in the SuperNEMO experiment. The principle of the detector operation is based on registering the delayed β-α coincidence from the uranium and thorium radioactive chains. The sensitivity of the detector is planned to be at the level of 208Tl < 2 μBq/kg and 214Bi < 10 μBq/kg. Alternate versions of the detector are described. The first results obtained by the prototype detector, operated in the Frejus Underground Laboratory in France, are presented.

  19. A critical assessment of the Burning Index in Los Angeles County, California

    USGS Publications Warehouse

    Schoenberg, F.P.; Chang, H.-C.; Keeley, J.E.; Pompa, J.; Woods, J.; Xu, H.

    2007-01-01

    The Burning Index (BI) is commonly used as a predictor of wildfire activity. An examination of data on the BI and wildfires in Los Angeles County, California, from January 1976 to December 2000 reveals that although the BI is positively associated with wildfire occurrence, its predictive value is quite limited. Wind speed alone has a higher correlation with burn area than BI, for instance, and a simple alternative point process model using wind speed, relative humidity, precipitation and temperature well outperforms the BI in terms of predictive power. The BI is generally far too high in winter and too low in fall, and may exaggerate the impact of individual variables such as wind speed or temperature during times when other variables, such as precipitation or relative humidity, render the environment ill suited for wildfires. ?? IAWF 2007.

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

    SciTech Connect

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

    2008-05-01

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

  1. Development of three-dimension microelectrode array for bioelectric measurement using the liquidmetal-micromolding technique

    SciTech Connect

    Liu, Ran Yang, Xueyao; Chen, Weixing; Jin, Cuiyun; Fu, Jingjing; Liu, Jing

    2013-11-04

    A method of manufacturing three-dimension microneedle electrode arrays is presented in this paper using the micromolding technology with liquid metal at room temperature, based on the physical property of the Bi-In-Sn liquid metal alloy, being its melting point especially low. Observed under scanning electron microscopy, the needle body of the electrode chip manufactured using this method has a good consistency. Skin penetration test in-vitro indicates that the microneedle electrode can pierce the stratum corneum and cross the high-impedance layer to acquire electrical signals. Electrical impedance and polarization voltage experimental results show that the electrode chips have great electric characteristics and meet the practical application demands.

  2. Bulk crystal growth and electronic characterization of the 3D Dirac semimetal Na{sub 3}Bi

    SciTech Connect

    Kushwaha, Satya K.; Krizan, Jason W.; Cava, R. J.; Feldman, Benjamin E.; Gyenis, András; Randeria, Mallika T.; Xiong, Jun; Xu, Su-Yang; Alidoust, Nasser; Belopolski, Ilya; Liang, Tian; Zahid Hasan, M.; Ong, N. P.; Yazdani, A.

    2015-04-01

    High quality hexagon plate-like Na{sub 3}Bi crystals with large (001) plane surfaces were grown from a molten Na flux. The freshly cleaved crystals were analyzed by low temperature scanning tunneling microscopy and angle-resolved photoemission spectroscopy, allowing for the characterization of the three-dimensional (3D) Dirac semimetal (TDS) behavior and the observation of the topological surface states. Landau levels were observed, and the energy-momentum relations exhibited a linear dispersion relationship, characteristic of the 3D TDS nature of Na{sub 3}Bi. In transport measurements on Na{sub 3}Bi crystals, the linear magnetoresistance and Shubnikov-de Haas quantum oscillations are observed for the first time.

  3. Temperature dependences of the gapwidth of A/sup IV/Se and A/sub 2//sup V/Se/sub 3/ semiconductors

    SciTech Connect

    Rasulov, S.M.

    1988-03-01

    The gapwidth of semiconductors E/sub g/ is related with the change in the enthalpy H/sub T/ - H/sub o/. The authors obtained a dependence between the temperature coefficient of the gapwidth and the heat capacity c/sub p/. They determined (par. deltaE/sub g//par. deltaT)p and E/sub g/(T) for semiconductors of the type A/sup IV/Se(A - Ge, Sn, Pb) and A/sub 2//sup V/Se/sub 3/ (A - As, Sb, Bi) in the solid and liquid states. For c/sub p/(T) and (H/sub T/ - H/sub o/)(T) based on the experimental data, empirical equations which are obeyed for temperatures above 273 K were derived.

  4. Postwall waveguide slot array with cosecant radiation pattern and null filling for base station antennas in local multidistributed systems

    NASA Astrophysics Data System (ADS)

    Hirokawa, J.; Yamazaki, C.; Ando, M.

    2002-04-01

    The authors propose to use planar antennas of waveguide slots with the simple structure of postwall waveguide for base station antennas in Local Multipoint Distribution Systems (LMDS). The array has a cosecant radiation pattern with null filling in the vertical plane for uniform illumination in a sector area. The slots are paired as an element to achieve traveling wave excitation because the phase, as well as the amplitude, has to be controlled for null filling in a cosecant pattern. It is the first time to design an array of reflection-canceling slot pairs to get a tapered distribution both in amplitude and phase. This paper extends the designability of the reflection-canceling slot arrays. A 16-element array is designed at 25-26 GHz band. The model array has a cosecant pattern with 3-dB deviations and a peak gain of 17.1 dBi in measurements.

  5. A Novel Compact Wideband TSA Array for Near-Surface Ice Sheet Penetrating Radar Applications

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Liu, Xiaojun; Fang, Guangyou

    2014-03-01

    A novel compact tapered slot antenna (TSA) array for near-surface ice sheet penetrating radar applications is presented. This TSA array is composed of eight compact antenna elements which are etched on two 480mm × 283mm FR4 substrates. Each antenna element is fed by a wideband coplanar waveguide (CPW) to coupled strip-line (CPS) balun. The two antenna substrates are connected together with a metallic baffle. To obtain wideband properties, another two metallic baffles are used along broadsides of the array. This array is fed by a 1 × 8 wideband power divider. The measured S11 of the array is less than -10dB in the band of 500MHz-2GHz, and the measured gain is more than 6dBi in the whole band which agrees well with the simulated results.

  6. Influence of Zn as a spallation product on the behaviour of martensitic steel T91 and austenitic steel 316L in liquid Pb-Bi

    NASA Astrophysics Data System (ADS)

    Deloffre, Ph.; Terlain, A.

    2004-11-01

    The liquid Pb-Bi alloy is proposed as material for the spallation target in hybrid systems. During the spallation process, several chemical elements are produced in the target which could generate specific liquid metal embrittlement phenomena. Among these species, zinc is known as an element which can promote LME (liquid metal embrittlement). Corrosion tests were carried out in liquid Pb-Bi in isothermal static conditions without and with 80 wppm of zinc at 150 °C, 350 °C and 600 °C up to 6000 h. No modification of the corrosion kinetics of T91 martensitic and 316L austenitic steels was observed for either unstressed or U-bend specimens with zinc in Pb-Bi. Moreover, no sign of embrittlement was observed for any of the samples with and without zinc.

  7. An autonomous in situ detection system for radioactivity measurements in the marine environment.

    PubMed

    Tsabaris, C; Bagatelas, C; Dakladas, Th; Papadopoulos, C T; Vlastou, R; Chronis, G T

    2008-10-01

    A new detection system named "KATERINA" is developed and applied for measuring marine radioactivity using NaI(Tl) as a crystal. This apparatus is designed for qualitative and quantitative radionuclide detection in the marine environment with maximum depth of deployment 400 m. A detailed study for the enclosure of the system and for the electronics development is performed. The system offers volumetric activities in Bq/m(3) using the marine efficiency calibration, which is measured by dilution of three reference sources ((99m)Tc, (137)Cs, and (40)K) in a special tank. The calibration procedures for energy, energy resolution and efficiency were analyzed with particular attention to the factors that affect the calibration parameters. The underwater detector is tested in the field for acquiring radon daughters ((214)Pb and (214)Bi) in a region where submarine groundwater discharge exists in the coastal zone. PMID:18372182

  8. Structural and optical investigation of Te-based chalcogenide thin films

    SciTech Connect

    Sharma, Rita Sharma, Shaveta; Thangaraj, R.; Mian, M.; Chander, Ravi; Kumar, Praveen

    2015-05-15

    We report the structural and optical properties of thermally evaporated Bi{sub 2}Te{sub 3}, In{sub 2}Te{sub 3} and InBiTe{sub 3} films by using X-ray diffraction, optical and Raman Spectroscopy techniques. The as-prepared thin films were found to be Semi-crystalline by X-ray diffraction. Particle Size and Strain has been calculated from XRD data. The optical constants, film thickness, refractive index and optical band gap (E{sub g}) has been reported for In{sub 2}Te{sub 3}, InBiTe{sub 3} films. Raman Spectroscopy was performed to investigate the effect of Bi, In, on lattice vibration and chemical bonding in Te based chalcogenide glassy alloys.

  9. Atomic-level structural and chemical analysis of Cr-doped Bi2Se3 thin films.

    PubMed

    Ghasemi, A; Kepaptsoglou, D; Collins-McIntyre, L J; Ramasse, Q; Hesjedal, T; Lazarov, V K

    2016-01-01

    We present a study of the structure and chemical composition of the Cr-doped 3D topological insulator Bi2Se3. Single-crystalline thin films were grown by molecular beam epitaxy on Al2O3 (0001), and their structural and chemical properties determined on an atomic level by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A regular quintuple layer stacking of the Bi2Se3 film is found, with the exception of the first several atomic layers in the initial growth. The spectroscopy data gives direct evidence that Cr is preferentially substituting for Bi in the Bi2Se3 host. We also show that Cr has a tendency to segregate at internal grain boundaries of the Bi2Se3 film. PMID:27221782

  10. Atomic-level structural and chemical analysis of Cr-doped Bi2Se3 thin films

    NASA Astrophysics Data System (ADS)

    Ghasemi, A.; Kepaptsoglou, D.; Collins-McIntyre, L. J.; Ramasse, Q.; Hesjedal, T.; Lazarov, V. K.

    2016-05-01

    We present a study of the structure and chemical composition of the Cr-doped 3D topological insulator Bi2Se3. Single-crystalline thin films were grown by molecular beam epitaxy on Al2O3 (0001), and their structural and chemical properties determined on an atomic level by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A regular quintuple layer stacking of the Bi2Se3 film is found, with the exception of the first several atomic layers in the initial growth. The spectroscopy data gives direct evidence that Cr is preferentially substituting for Bi in the Bi2Se3 host. We also show that Cr has a tendency to segregate at internal grain boundaries of the Bi2Se3 film.

  11. Managing Sustainability with the Support of Business Intelligence Methods and Tools

    NASA Astrophysics Data System (ADS)

    Petrini, Maira; Pozzebon, Marlei

    In this paper we explore the role of business intelligence (BI) in helping to support the management of sustainability in contemporary firms. The concepts of sustainability and corporate social responsibility (CSR) are among the most important themes to have emerged in the last decade at the global level. We suggest that BI methods and tools have an important but not yet well studied role to play in helping organizations implement and monitor sustainable and socially responsible business practices. Using grounded theory, the main contribution of our study is to propose a conceptual model that seeks to support the process of definition and monitoring of socio-environmental indicators and the relationship between their management and business strategy.

  12. Two-Step Annealing Leading to Refined Bi2Te3-In2Te3 Lamellar Structures for Tuning of Thermoelectric Properties

    NASA Astrophysics Data System (ADS)

    Liu, Dongmei; Li, Xinzhong; Schmechel, Roland; Rettenmayr, Markus

    2016-03-01

    A two-step annealing process was applied to control the morphology of Bi2Te3-In2Te3 composite materials via precipitation of In2Te3 from supersaturated (Bi,In)2Te3. Finer lamellae were obtained via two-step as compared with single-step isothermal annealing. The microstructure was optimized by exploiting thermodynamic and kinetic effects during nucleation and growth of In2Te3. The relationship between the morphologies and thermoelectric properties was analyzed. With preannealing at a lower temperature, refined morphologies lead to an enhanced power factor and zT in the temperature range from room temperature to ˜100°C. The enhancement is mainly caused by an increased Seebeck coefficient, most probably due to energy-dependent scattering processes. However, the thermal conductivity is dominated by bipolar thermal transport that compensates the low lattice thermal conductivity completely.

  13. Development of three-dimension microelectrode array for bioelectric measurement using the liquidmetal-micromolding technique

    NASA Astrophysics Data System (ADS)

    Liu, Ran; Yang, Xueyao; Jin, Cuiyun; Fu, Jingjing; Chen, Weixing; Liu, Jing

    2013-11-01

    A method of manufacturing three-dimension microneedle electrode arrays is presented in this paper using the micromolding technology with liquid metal at room temperature, based on the physical property of the Bi-In-Sn liquid metal alloy, being its melting point especially low. Observed under scanning electron microscopy, the needle body of the electrode chip manufactured using this method has a good consistency. Skin penetration test in-vitro indicates that the microneedle electrode can pierce the stratum corneum and cross the high-impedance layer to acquire electrical signals. Electrical impedance and polarization voltage experimental results show that the electrode chips have great electric characteristics and meet the practical application demands.

  14. Leveraging business intelligence to make better decisions: Part II.

    PubMed

    Reimers, Mona

    2014-01-01

    This article is the second in a series about business intelligence (BI) in a medical practice. The first article reviewed the evolution of data reporting within the industry and provided some examples of how BI concepts differ from the reports available in the menus of our software systems, or the dashboards and scorecards practices have implemented. This article will discuss how to begin a BI initiative for front-end medical practice staffers that will create tools they can use to reduce errors and increase efficiency throughout their workday. This type of BI rollout can allow practices to get started with very little financial investment, gain enthusiasm from end users, and achieve a quick return on investment. More examples of successful BI projects in medical practices are discussed to help illustrate BI concepts. PMID:25108990

  15. Infrared surface polaritons on bismuth

    NASA Astrophysics Data System (ADS)

    Khalilzadeh-Rezaie, Farnood; Smith, Christian W.; Nath, Janardan; Nader, Nima; Shahzad, Monas; Cleary, Justin W.; Avrutsky, Ivan; Peale, Robert E.

    2015-01-01

    Optical constants for evaporated bismuth (Bi) films were measured by ellipsometry and compared with those published for single crystal and melt-cast polycrystalline Bi in the wavelength range of 1 to 40 μm. The bulk plasma frequency ωp and high-frequency limit to the permittivity ε∞ were determined from the long-wave portion of the permittivity spectrum, taking previously published values for the relaxation time τ and effective mass m*. This part of the complex permittivity spectrum was confirmed by comparing calculated and measured reflectivity spectra in the far-infrared. Properties of surface polaritons (SPs) in the long-wave infrared were calculated to evaluate the potential of Bi for applications in infrared plasmonics. Measured excitation resonances for SPs on Bi lamellar gratings agree well with calculated resonance spectra based on grating geometry and complex permittivity.

  16. Development of MnBi permanent magnet: Neutron diffraction of MnBi powder

    SciTech Connect

    Cui, J; Choi, JP; Li, G; Polikarpov, E; Darsell, J; Kramer, MJ; Zarkevich, NA; Wang, LL; Johnson, DD; Marinescu, M; Huang, QZ; Wu, H; Vuong, NV; Liu, JP

    2014-05-07

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained powder. The result shows that the purity of the obtained powder is about 91 wt. % at 300 K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 mu(B) at 50 K and 300 K, respectively. (C) 2014 AIP Publishing LLC.

  17. Development of MnBi permanent magnet: neutron diffraction of MnBi powder

    SciTech Connect

    Cui, Jun; Choi, Jung-Pyung; Li, Guosheng; Polikarpov, Evgueni; Darsell, Jens T.; Kramer, Matthew J.; Zarkevich, Nikolai; Wang, L. L.; Johnson, D. D.; Marinescu, Melania; Huang, Qingzhen; Wu, Hui; Vuong, Nguyen V.; Liu, J.Ping

    2014-03-05

    MnBi attracts great attention in recent years for its great potential as permanent magnet materials. MnBi phase is difficult to obtain because of the rather drastic peritectic reaction between Mn and Bi. In this paper, we report our effort on synthesizing high purity MnBi compound using conventional powder metallurgical approaches. Neutron diffraction was carried out to investigate the crystal and nuclear structure of the obtained power. The result shows that the purity of the obtained powder is about 91wt.% at 300K, and the magnetic moment of the Mn atom in MnBi lattice is 4.424 and 4.013 μB at 50 K and 300 K respectively.

  18. Bismuth-induced deep levels and carrier compensation in CdTe

    SciTech Connect

    Du, Mao-Hua

    2008-01-01

    First-principles calculations show that Bi on Cd site in CdTe can be either a donor, Bi_Cd+, or an acceptor, Bi_Cd- , depending on the Fermi level. The can bind a substitutional O (O_Te) with large binding energy of 1.40 eV. The calculated (0/-) transition level for B_Cd- - O_Te complex is in good agreement with the observed deep hole trapping level. Bi can also substitute Te to form an acceptor. The amphoteric nature of Bi in CdTe results in the pinning of the Fermi level and the high resistivity. We also discuss the origin of p-type CdTe at high Bi doping level.

  19. Research on defects and transport in amorphous-silicon-based semiconductors. Final subcontract report, 20 February 1991--19 April 1994

    SciTech Connect

    Schiff, E.A.; Antoniadis, H.; Gu, Q.; Lee, J.K.; Wang, Q.; Zafar, S.

    1994-09-01

    This report describes work on three individual tasks as follows. (1) Electron and hole drift measurements in a-Si{sub 1-x}Ge{sub x}:H and a-Si{sub 1-x}C{sub x}:H p-i-n solar cells. Multijunction solar cells incorporating modified band gap a-Si:H in a triple-junction structure are generally viewed as the most promising avenue for achieving an amorphous silicon-based solar call with 15% stabilized conversion efficiency. The specific objective of this task was to document the mobilities and deep-trapping mobility-lifetime products for electrons and holes in a-Si{sub 1-x}Ge{sub x}:H and a-Si{sub 1-x}C{sub x}:H alloys materials. (2) Electroabsorption measurements and built-in potential (V{sub bi}) in solar cells. V{sub bi} in a p-i-n solar call may be limiting the open-circuit voltage (V{sub oc}) in wide-band-gap cells (E{sub g} > 1.8 eV) currently under investigation as the top cell for 15% triple junction devices. The research addressed four issues that need to be resolved before the method can yield an error less than 0.1 V for V{sub bi}. The details are presented in this report. (3) Defect relaxation and Shockley-Read kinetics in a-Si:H. Quantitative modeling of solar cells is usually based on Shockley-Read kinetics.`` An important assumption of this approach is that the rate of emission of a photocarrier trapped on a defect is independent of quasi-Fermi level location.

  20. Phase transfer hollow fiber liquid phase microextraction combined with electrothermal vaporization inductively coupled plasma mass spectrometry for the determination of trace heavy metals in environmental and biological samples.

    PubMed

    Guo, Xueqin; He, Man; Chen, Beibei; Hu, Bin

    2012-11-15

    A new method of phase transfer hollow fiber liquid phase microextraction (PT-HF-LPME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) has been developed for the determination of trace Co, Pd, Cd and Bi in environmental and biological samples. In PT-HF-LPME, an intermediate solvent (1-butanol) was added into the sample solution to ensure the maximum contact area between the target metal ions and the chelating reagent (8-hydroxyquinoline, 8-HQ), which accelerated the formation of 8-HQ-metal complexes and their subsequent extraction by extraction solvent (toluene). The experimental parameters affecting the extraction efficiency of PT-HF-LPME for the target metals were studied by simplex optimization and orthogonal array design (OAD) experiments. Under the optimized conditions, the enrichment factors for Co, Pd, Cd and Bi were 110, 393, 121 and 111-fold, respectively, the limits of detection (LODs, 3σ) ranged from 3.7 to 8.3 ng L(-1). The relative standard deviations (RSDs, c=0.5 ng mL(-1), n=7) were 8.7, 6.2, 12.4 and 12.9% for Co, Pd, Cd and Bi, respectively. To validate the accuracy of the proposed method, two Certified Reference Materials of GSBZ50009-88 Environment Water and GBW09103 Human Urine were analyzed, and the results obtained for Cd were in good agreement with the certified values. Finally, the developed method was successfully applied to the analysis of Co, Pd, Cd and Bi in lake water and human urine samples. PMID:23158357

  1. Atlas Assimilation Patterns in Different Types of Adult Craniocervical Junction Malformations

    PubMed Central

    Ferreira, Edson Dener Zandonadi; Botelho, Ricardo Vieira

    2015-01-01

    Study Design. This is a cross-sectional analysis of resonance magnetic images of 111 patients with craniocervical malformations and those of normal subjects. Objective. To test the hypothesis that atlas assimilation is associated with basilar invagination (BI) and atlas's anterior arch assimilation is associated with craniocervical instability and type I BI. Summary of Background Data. Atlas assimilation is the most common malformation in the craniocervical junction. This condition has been associated with craniocervical instability and BI in isolated cases. Methods. We evaluated midline Magnetic Resonance Images (MRIs) (and/or CT scans) from patients with craniocervical junction malformation and normal subjects. The patients were separated into 3 groups: Chiari type I malformation, BI type I, and type II. The atlas assimilations were classified according to their embryological origins as follows: posterior, anterior, and both arches assimilation. Results. We studied the craniometric values of 111 subjects, 78 with craniocervical junction malformation and 33 without malformations. Of the 78 malformations, 51 patients had Chiari type I and 27 had BI, of whom 10 presented with type I and 17 with type II BI. In the Chiari group, 41 showed no assimilation of the atlas. In the type I BI group, all patients presented with anterior arch assimilation, either in isolation or associated with assimilation of the posterior arch. 63% of the patients with type II BI presented with posterior arch assimilation, either in isolation or associated with anterior arch assimilation. In the control group, no patients had atlas assimilation. Conclusion. Anterior atlas assimilation leads to type I BI. Posterior atlas assimilation more frequently leads to type II BI. Separation in terms of anterior versus posterior atlas assimilation reflects a more accurate understanding of the clinical and embryological differences in craniocervical junction malformations. Level of Evidence: N/A PMID

  2. Formation of a Protein Corona on Silver Nanoparticles Mediates Cellular Toxicity via Scavenger Receptors

    PubMed Central

    Shannahan, Jonathan H.; Podila, Ramakrishna; Aldossari, Abdullah A.; Emerson, Hilary; Powell, Brian A.; Ke, Pu Chun; Rao, Apparao M.; Brown, Jared M.

    2015-01-01

    Addition of a protein corona (PC) or protein adsorption layer on the surface of nanomaterials following their introduction into physiological environments may modify their activity, bio-distribution, cellular uptake, clearance, and toxicity. We hypothesize that silver nanoparticles (AgNPs) will associate with proteins common to human serum and cell culture media forming a PC that will impact cell activation and cytotoxicity. Furthermore, the role of scavenger receptor BI (SR-BI) in mediating this toxicity was evaluated. Citrate-suspended 20 nm AgNPs were incubated with human serum albumin (HSA), bovine serum albumin (BSA), high-density lipoprotein (HDL), or water (control) to form a PC. AgNPs associated with each protein (HSA, BSA, and HDL) forming PCs as assessed by electron microscopy, hyperspectral analysis, ζ-potential, and hydrodynamic size. Addition of the PC decreased uptake of AgNPs by rat lung epithelial and rat aortic endothelial cells. Hyperspectral analysis demonstrated a loss of the AgNP PC following internalization. Cells demonstrated concentration-dependent cytotoxicity following exposure to AgNPs with or without PCs (0, 6.25, 12.5, 25 or 50 μg/ml). All PC-coated AgNPs were found to activate cells by inducing IL-6 mRNA expression. A small molecule SR-BI inhibitor was utilized to determine the role of SR-BI in the observed effects. Pretreatment with the SR-BI inhibitor decreased internalization of AgNPs with or without PCs, and reduced both cytotoxicity and IL-6 mRNA expression. This study characterizes the formation of a PC on AgNPs and demonstrates its influence on cytotoxicity and cell activation through a cell surface receptor. PMID:25326241

  3. Scavenger receptor class B type I (SR-BI) is involved in vitamin E transport across the enterocyte

    PubMed Central

    Reboul, Emmanuelle; Klein, Alexis; Bietrix, Florence; Gleize, Béatrice; Malezet-Desmoulins, Christiane; Schneider, Martina; Margotat, Alain; Lagrost, Laurent; Collet, Xavier; Borel, Patrick

    2006-01-01

    Although cellular uptake of vitamin E was initially described as a passive process, recent studies in the liver and brain have shown that SR-BI is involved in this phenomenon. As SR-BI is expressed at high levels in the intestine, the present study addressed the involvement of SR-BI in vitamin E trafficking across enterocytes. Apical uptake and efflux of the main dietary forms of vitamin E was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium. RRR-γ-tocopherol bioavailability was compared between wild-type mice and mice overexpressing SR-BI in the intestine. The effect of vitamin E on enterocyte SR-BI mRNA levels was measured by real-time quantitative RT-PCR. Concentration-dependent curves for vitamin E uptake were similar for RRR-α-, RRR-γ- and DL-α-tocopherol. RRR-α-tocopherol transport was dependent on incubation temperature, with a 60% reduction in absorption at 4°C compared to 37°C (p<0.05). Vitamin E flux in enterocytes was directed from the apical to the basal side, with a relative 10-fold reduction in the transfer process when measured in the opposite direction (p<0.05). Co-incubation with cholesterol, γ-tocopherol or lutein significantly impaired α-tocopherol absorption. Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 80% of vitamin E uptake and up to 30 % of apical vitamin E efflux (p<0.05), and similar results were obtained for RRR-γ-tocopherol. SR-BI mRNA levels were not significantly modified after a 24-hour incubation of Caco-2 cells with vitamin E. Finally, RRR-γ-tocopherol bioavailability was 2.7-fold higher in mice overexpressing SR-BI than in wild-type mice (p<0.05). The present data show for the first time that vitamin E intestinal absorption is, at least partly, mediated by SR-BI. PMID:16380385

  4. Brain injury-associated biomarkers of TGF-beta1, S100B, GFAP, NF-L, tTG, AbetaPP, and tau were concomitantly enhanced and the UPS was impaired during acute brain injury caused by Toxocara canis in mice

    PubMed Central

    Liao, Chien-Wei; Fan, Chia-Kwung; Kao, Ting-Chang; Ji, Dar-Der; Su, Kua-Eyre; Lin, Yun-Ho; Cho, Wen-Long

    2008-01-01

    Background Because the outcomes and sequelae after different types of brain injury (BI) are variable and difficult to predict, investigations on whether enhanced expressions of BI-associated biomarkers (BIABs), including transforming growth factor β1 (TGF-β1), S100B, glial fibrillary acidic protein (GFAP), neurofilament light chain (NF-L), tissue transglutaminases (tTGs), β-amyloid precursor proteins (AβPP), and tau are present as well as whether impairment of the ubiquitin-proteasome system (UPS) is present have been widely used to help delineate pathophysiological mechanisms in various BIs. Larvae of Toxocara canis can invade the brain and cause BI in humans and mice, leading to cerebral toxocariasis (CT). Because the parasitic burden is light in CT, it may be too cryptic to be detected in humans, making it difficult to clearly understand the pathogenesis of subtle BI in CT. Since the pathogenesis of murine toxocariasis is very similar to that in humans, it appears appropriate to use a murine model to investigate the pathogenesis of CT. Methods BIAB expressions and UPS function in the brains of mice inoculated with a single dose of 250 T. canis embryonated eggs was investigated from 3 days (dpi) to 8 weeks post-infection (wpi) by Western blotting and RT-PCR. Results Results revealed that at 4 and 8 wpi, T. canis larvae were found to have invaded areas around the choroid plexus but without eliciting leukocyte infiltration in brains of infected mice; nevertheless, astrogliosis, an indicator of BI, with 78.9~142.0-fold increases in GFAP expression was present. Meanwhile, markedly increased levels of other BIAB proteins including TGF-β1, S100B, NF-L, tTG, AβPP, and tau, with increases ranging 2.0~12.0-fold were found, although their corresponding mRNA expressions were not found to be present at 8 wpi. Concomitantly, UPS impairment was evidenced by the overexpression of conjugated ubiquitin and ubiquitin in the brain. Conclusion Further studies are needed to

  5. Treatment of Infections in Young Infants in Low- and Middle-Income Countries: A Systematic Review and Meta-analysis of Frontline Health Worker Diagnosis and Antibiotic Access

    PubMed Central

    Lee, Anne CC; Chandran, Aruna; Herbert, Hadley K.; Kozuki, Naoko; Markell, Perry; Shah, Rashed; Campbell, Harry; Rudan, Igor; Baqui, Abdullah H.

    2014-01-01

    Background Inadequate illness recognition and access to antibiotics contribute to high case fatality from infections in young infants (<2 months) in low- and middle-income countries (LMICs). We aimed to address three questions regarding access to treatment for young infant infections in LMICs: (1) Can frontline health workers accurately diagnose possible bacterial infection (pBI)?; (2) How available and affordable are antibiotics?; (3) How often are antibiotics procured without a prescription? Methods and Findings We searched PubMed, Embase, WHO/Health Action International (HAI), databases, service provision assessments (SPAs), Demographic and Health Surveys, Multiple Indicator Cluster Surveys, and grey literature with no date restriction until May 2014. Data were identified from 37 published studies, 46 HAI national surveys, and eight SPAs. For study question 1, meta-analysis showed that clinical sign-based algorithms predicted bacterial infection in young infants with high sensitivity (87%, 95% CI 82%–91%) and lower specificity (62%, 95% CI 48%–75%) (six studies, n = 14,254). Frontline health workers diagnosed pBI in young infants with an average sensitivity of 82% (95% CI 76%–88%) and specificity of 69% (95% CI 54%–83%) (eight studies, n = 11,857) compared to physicians. For question 2, first-line injectable agents (ampicillin, gentamicin, and penicillin) had low variable availability in first-level health facilities in Africa and South Asia. Oral amoxicillin and cotrimoxazole were widely available at low cost in most regions. For question 3, no studies on young infants were identified, however 25% of pediatric antibiotic purchases in LMICs were obtained without a prescription (11 studies, 95% CI 18%–34%), with lower rates among infants <1 year. Study limitations included potential selection bias and lack of neonatal-specific data. Conclusions Trained frontline health workers may screen for pBI in young infants with relatively high sensitivity

  6. Structure-property-performance relationships of new high temperature relaxors for capacitor applications

    NASA Astrophysics Data System (ADS)

    Stringer, Craig J.

    This thesis extends the investigations on perovskite solid solutions based on PbTiO3-Bi(Me',Me")O3 (Me' = Sc3+, Zn2+, Mg2+, Ni2+, In3+ , Fe3+, etc. and Me" = Ti4+, Nb 5+, W6+) systems. The ferroelectric transition temperature (TC) behavior was considered in the tetragonal phase region of the PbTiO 3-Bi(Me',Me")O3 systems. Trends in the TC compositional dependence exhibited three main cases: case 1, a continued increase in transition temperature above the end-member PbTiO3 (495°C); case 2, an increase and then decrease of the transition temperature; and case 3, a continuous decrease in the transition temperature with Bi(Me',Me")O 3 additions. New relaxor materials were developed from the PbTiO3-Bi(Me',Me")O 3 solid solutions; specifically, the Bi(Mg3/4W1/4)O 3-PbTiO3 (BMW-PT) binary solid solution and BiScO3-Pb(Mg 1/3Nb2/3)O3-PbTiO3 (BS-PMN-PT) ternary solid solution were investigated. Permittivity, polarization and pyroelectric measurements were performed on BMW-PT and BS-PMN-PT compositions with respect to temperature with characteristic relaxor behavior observed. The complex solid solution BMW-PT exhibited a morphotropic phase boundary at ˜48 mol% PbTiO3 with a corresponding TC of 205°C. On further structural analysis with diffraction contrast transmission electron microscopy along with x-ray diffraction, evidence of B-site ordering was observed. The BS-PMN-PT proved to be a model system with high temperature relaxor properties of Tmax ˜ 250°C to 300°C and εmax ˜ 14,000 to 17,000 at 1 kHz. The deviation temperature, TD, or temperature of the onset of local spontaneous polarization, was determined by thermal strain measurement and high temperature dielectric measurement to be approximately 600°C; up to 250°C higher than any reported value for relaxor ferroelectrics. The frequency dependence of the temperature of the permittivity maximum was found to follow the Vogel-Fulcher relationship, with an activation energy (EA) of ˜0.1 eV, and a freezing

  7. Bile acids reduce endocytosis of high-density lipoprotein (HDL) in HepG2 cells.

    PubMed

    Röhrl, Clemens; Eigner, Karin; Fruhwürth, Stefanie; Stangl, Herbert

    2014-01-01

    High-density lipoprotein (HDL) transports lipids to hepatic cells and the majority of HDL-associated cholesterol is destined for biliary excretion. Cholesterol is excreted into the bile directly or after conversion to bile acids, which are also present in the plasma as they are effectively reabsorbed through the enterohepatic cycle. Here, we provide evidence that bile acids affect HDL endocytosis. Using fluorescent and radiolabeled HDL, we show that HDL endocytosis was reduced in the presence of high concentrations of taurocholate, a natural non-cell-permeable bile acid, in human hepatic HepG2 and HuH7 cells. In contrast, selective cholesteryl-ester (CE) uptake was increased. Taurocholate exerted these effects extracellularly and independently of HDL modification, cell membrane perturbation or blocking of endocytic trafficking. Instead, this reduction of endocytosis and increase in selective uptake was dependent on SR-BI. In addition, cell-permeable bile acids reduced HDL endocytosis by farnesoid X receptor (FXR) activation: chenodeoxycholate and the non-steroidal FXR agonist GW4064 reduced HDL endocytosis, whereas selective CE uptake was unaltered. Reduced HDL endocytosis by FXR activation was independent of SR-BI and was likely mediated by impaired expression of the scavenger receptor cluster of differentiation 36 (CD36). Taken together we have shown that bile acids reduce HDL endocytosis by transcriptional and non-transcriptional mechanisms. Further, we suggest that HDL endocytosis and selective lipid uptake are not necessarily tightly linked to each other. PMID:25010412

  8. Three dimensional multilayer solenoid microcoils inside silica glass

    NASA Astrophysics Data System (ADS)

    Meng, Xiangwei; Yang, Qing; Chen, Feng; Shan, Chao; Liu, Keyin; Li, Yanyang; Bian, Hao; Si, Jinhai; Hou, Xun

    2016-01-01

    Three dimensional (3D) solenoid microcoils could generate uniform magnetic field. Multilayer solenoid microcoils are highly pursued for strong magnetic field and high inductance in advanced magnetic microsystems. However, the fabrication of the 3D multilayer solenoid microcoils is still a challenging task. In this paper, 3D multilayer solenoid microcoils with uniform diameters and high aspect ratio were fabricated in silica glass. An alloy (Bi/In/Sn/Pb) with high melting point was chosen as the conductive metal to overcome the limitation of working temperature and improve the electrical property. The inductance of the three layers microcoils was measured, and the value is 77.71 nH at 100 kHz and 17.39 nH at 120 MHz. The quality factor was calculated, and it has a value of 5.02 at 120 MHz. This approach shows an improvement method to achieve complex 3D metal microstructures and electronic components, which could be widely integrated in advanced magnetic microsystems.

  9. Melting and Solidification Behaviour of Bi-Pb Multiphase Alloy Nanoparticles Embedded in Aluminum Matrix.

    PubMed

    Khan, Patan Yousaf; Biswas, Krishanu

    2015-01-01

    The present investigation reports the result of the investigation on the phase transformation of biphasic Bi-Pb alloy nanoparticles embedded in the aluminum matrix. The samples are prepared by rapid solidification route involving melt spinning of Al-6 wt% (Bi55.9Pb44.1) alloy on a rotating copper wheel in an argon-filled evacuated chamber. The detailed transmission electron microscope (TEM) investigation shows presence of near cuboctahedral shaped biphasic nano-inclusions consisting of the (Bi) solid solution and β, the intermediate phase. β constitutes bulk of the nanoparticle with (Bi) forming the cap. Both the phases bear distinct orientation relationship with the matrix. The compositional analysis indicates substantial increase in solid solubilities of Pb in the (Bi) and Bi in the β-phases as compared to the as-cast sample. Differential scanning calorimetric (DSC) studies indicate substantial superheating (16.4 K) of the embedded nanoparticles with appearance of sharp melting peak. The solidification is observed to be diffused, taking place over a large temperature range (344.5 K to 332 K). The in situ heating stage experiments carried out in TEM indicate formation of core shell morphology during heating with β forming the shell around (Bi). The melting starts from Al/β/(Bi) triple point and then the liquid spreads along matrix-particle interface. The solidification occurs in eutectic manner. PMID:26328350

  10. Liver growth factor induces testicular regeneration in EDS-treated rats and increases protein levels of class B scavenger receptors.

    PubMed

    Lobo, M V T; Arenas, M I; Huerta, L; Sacristán, S; Pérez-Crespo, M; Gutiérrez-Adán, A; Díaz-Gil, J J; Lasunción, M A; Martín-Hidalgo, A

    2015-01-15

    The aim of the present work was to determine the effects of liver growth factor (LGF) on the regeneration process of rat testes after chemical castration induced by ethane dimethanesulfonate (EDS) by analyzing some of the most relevant proteins involved in cholesterol metabolism, such as hormone sensitive lipase (HSL), 3β-hydroxysteroid dehydrogenase (3β-HSD), scavenger receptor SR-BI, and other components of the SR family that could contribute to the recovery of steroidogenesis and spermatogenesis in the testis. Sixty male rats were randomized to nontreated (controls) and LGF-treated, EDS-treated, and EDS + LGF-treated groups. Testes were obtained on days 10 (T1), 21 (T2), and 35 (T3) after EDS treatment, embedded in paraffin, and analyzed by immunohistochemistry and Western blot. LGF improved the recovery of the seminiferous epithelia, the appearance of the mature pattern of Leydig cell interstitial distribution, and the expression of mature SR-BI. Moreover, LGF treatment resulted in partial recovery of HSL expression in Leydig cells and spermatogonia. No changes in serum testosterone were observed in control or LGF-treated rats, but in EDS-castrated animals LGF treatment induced a progressive increase in serum testosterone levels and 3β-HSD expression. Based on the pivotal role of SR-BI in the uptake of cholesteryl esters from HDL, it is suggested that the observed effects of LGF would facilitate the provision of cholesterol for sperm cell growth and Leydig cell recovery. PMID:25389365

  11. Determination of heavy metals by inductively coupled plasma mass spectrometry after on-line separation and preconcentration

    NASA Astrophysics Data System (ADS)

    Dressler, Valderi L.; Pozebon, Dirce; Curtius, Adilson J.

    1998-10-01

    A method for the determination of Cu, As, Se, Cd, In, Hg, Tl, Pb and Bi in waters and in biological materials by inductively coupled plasma mass spectrometry, after an on-line separation, is described. The matrix separation and analyte preconcentration is accomplished by retention of the analytes complexed with the ammonium salt of O,O-diethyl dithiophosphoric acid in a HNO 3 solution on C 18 immobilized on silica in a minicolumn. Methanol, as eluent, is introduced in the conventional pneumatic nebulizer of the instrument. In order to use the best compromise conditions, concerning the ligand and acid concentrations, the analytes were determined in two separate groups. The enrichment factors were in the range from 5 to 61, depending on the analyte. The limits of detection varied from 0.43 ng L -1 for Bi to 33 ng L -1 for Cu. The sample consumption is only 2.3 mL for each group and the sampling frequency is 21 h -1. The accuracy was tested by analysing five certified reference materials: water, riverine water, urine, bovine muscle and bovine liver. The agreement between obtained and certified concentrations was very good, except for As. The relatively small volume of methanol, used as eluent, minimizes the problems produced by the introduction of organic solvent into the plasma.

  12. Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering

    PubMed Central

    Çınar, Simge; Tevis, Ian D.; Chen, Jiahao; Thuo, Martin

    2016-01-01

    Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate (‘/’ = physisorbed, ‘-’ = chemisorbed), from molten Field’s metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity. PMID:26902483

  13. EM study of latent track morphology in TiO2 single crystals

    NASA Astrophysics Data System (ADS)

    O'Connell, J. H.; Skuratov, V. A.; Akilbekov, A.; Zhumazhanova, A.; Janse van Vuuren, A.

    2016-07-01

    A TEM investigation was conducted into the morphology of 167 MeV Xe (2 × 1010 cm-2 to 1014 cm-2) and 1 GeV Bi ion (2 × 1010 cm-2) induced latent tracks in single crystal TiO2 (rutile). At fluences up to 1011 cm-2 latent tracks are visible as discontinuous lines of strained crystal along the ion trajectory. From the implanted surface down to about 60-70 nm below the surface the tracks appear as continuous conical structures with a base of diameter 5-6 nm (Xe) and 8-9 nm (Bi) in contact with the surface with a mushroom shaped hillock extending outward from the surface. At fluences between 6 × 1012 cm-2 and 1013 cm-2 the crystal is amorphized but rod-like crystalline regions remain which are oriented along the ion trajectories. Amorphization extends from the surface down to 8.3 μm below suggesting an upper limit for the threshold electronic stopping power for amorphization of 7.3 keV nm-1. At 1014 cm-2 Xe the entire 8.3 μm subsurface region is rendered amorphous although some evidence of short range ordering remains.

  14. Impact of individual acute phase serum amyloid A isoforms on HDL metabolism in mice.

    PubMed

    Kim, Myung-Hee; de Beer, Maria C; Wroblewski, Joanne M; Charnigo, Richard J; Ji, Ailing; Webb, Nancy R; de Beer, Frederick C; van der Westhuyzen, Deneys R

    2016-06-01

    The acute phase (AP) reactant serum amyloid A (SAA), an HDL apolipoprotein, exhibits pro-inflammatory activities, but its physiological function(s) are poorly understood. Functional differences between SAA1.1 and SAA2.1, the two major SAA isoforms, are unclear. Mice deficient in either isoform were used to investigate plasma isoform effects on HDL structure, composition, and apolipoprotein catabolism. Lack of either isoform did not affect the size of HDL, normally enlarged in the AP, and did not significantly change HDL composition. Plasma clearance rates of HDL apolipoproteins were determined using native HDL particles. The fractional clearance rates (FCRs) of apoA-I, apoA-II, and SAA were distinct, indicating that HDL is not cleared as intact particles. The FCRs of SAA1.1 and SAA2.1 in AP mice were similar, suggesting that the selective deposition of SAA1.1 in amyloid plaques is not associated with a difference in the rates of plasma clearance of the isoforms. Although the clearance rate of SAA was reduced in the absence of the HDL receptor, scavenger receptor class B type I (SR-BI), it remained significantly faster compared with that of apoA-I and apoA-II, indicating a relatively minor role of SR-BI in SAA's rapid clearance. These studies enhance our understanding of SAA metabolism and SAA's effects on AP-HDL composition and catabolism. PMID:27018443

  15. Effects of Ce Addition on the Microstructure and Mechanical Properties of Sn-58Bi Solder Joints

    NASA Astrophysics Data System (ADS)

    Chuang, Tung-Han; Wu, Hsing-Fei

    2011-01-01

    The effects of a rare-earth element on the microstructure, mechanical properties, and whisker growth of Sn-58Bi alloys and solder joints in ball grid array (BGA) packages with Ag/Cu pads have been investigated. Mechanical testing indicated that the elongation of Sn-58Bi alloys doped with Ce increased significantly, and the tensile strength decreased slightly, in compar- ison with undoped Sn-58Bi. In addition, the growth of both fiber- and hillock-shaped tin whiskers on the surface of Sn-58Bi-0.5Ce was retarded in the case of Sn-3Ag-0.5Cu-0.5Ce alloys. The growth of interfacial intermetallic compounds (IMC) in Sn-58Bi-0.5Ce solder joints was slower than that in Sn-58Bi because the activity of Ce atoms at the interface of the Cu6Sn5 IMC/solder was reduced. The reflowed Sn-58Bi and Sn-58Bi-0.5Ce BGA packages with Ag/Cu pads had a ball shear strength of 7.91 N and 7.64 N, which decreased to about 7.13 N and 6.87 N after aging at 100°C for 1000 h, respectively. The reflowed and aged solder joints fractured across the solder balls with ductile characteristics after ball shear tests.

  16. Macrophage-mediated cholesterol handling in atherosclerosis.

    PubMed

    Chistiakov, Dimitry A; Bobryshev, Yuri V; Orekhov, Alexander N

    2016-01-01

    Formation of foam cells is a hallmark at the initial stages of atherosclerosis. Monocytes attracted by pro-inflammatory stimuli attach to the inflamed vascular endothelium and penetrate to the arterial intima where they differentiate to macrophages. Intimal macrophages phagocytize oxidized low-density lipoproteins (oxLDL). Several scavenger receptors (SR), including CD36, SR-A1 and lectin-like oxLDL receptor-1 (LOX-1), mediate oxLDL uptake. In late endosomes/lysosomes of macrophages, oxLDL are catabolysed. Lysosomal acid lipase (LAL) hydrolyses cholesterol esters that are enriched in LDL to free cholesterol and free fatty acids. In the endoplasmic reticulum (ER), acyl coenzyme A: cholesterol acyltransferase-1 (ACAT1) in turn catalyses esterification of cholesterol to store cholesterol esters as lipid droplets in the ER of macrophages. Neutral cholesteryl ester hydrolases nCEH and NCEH1 are involved in a secondary hydrolysis of cholesterol esters to liberate free cholesterol that could be then out-flowed from macrophages by cholesterol ATP-binding cassette (ABC) transporters ABCA1 and ABCG1 and SR-BI. In atherosclerosis, disruption of lipid homoeostasis in macrophages leads to cholesterol accumulation and formation of foam cells. PMID:26493158

  17. Data-driven Casualty Estimation and Disease Nonbattle Injury/Battle Injury Rates in Recent Campaigns.

    PubMed

    Wojcik, Barbara E; Humphrey, Rebecca J; Hosek, Barbara J; Stein, Catherine R

    2016-01-01

    To ensure Soldiers are properly equipped and mission capable to perform full spectrum operations, Army medical planners use disease nonbattle injury (DNBI) and battle injury (BI) admission rates in the Total Army Analysis process to support medical deployment and force structure planning for deployed settings. For more than a decade, as the proponent for the DNBI/BI methodology and admission rates, the Statistical Analysis Cell (previously Statistical Analysis Branch, Center for Army Medical Department Strategic Studies) has provided Army medical planners with DNBI/BI rates based upon actual data from recent operations. This article presents the data-driven methodology and casualty estimation rates developed by the Statistical Analysis Cell and accredited for use by 2 Army Surgeon Generals, displays the top 5 principal International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) diagnoses for DNBI/BI in Operation Iraqi Freedom/Operation New Dawn (OIF/OND), and discusses trends in DNBI rates in OIF/OND during the stabilization period. Our methodology uses 95th percentile daily admission rates as a planning factor to ensure that 95% of days in theater are supported by adequate staff and medical equipment. We also present our DNBI/BI estimation methodology for non-Army populations treated at Role 3 US Army medical treatment facilities. PMID:27215860

  18. Liquid-solid phase transition alloy as reversible and rapid molding bone cement.

    PubMed

    Yi, Liting; Jin, Chao; Wang, Lei; Liu, Jing

    2014-12-01

    Acrylic bone cement has been an essential non-metallic implant used as fixing agent in the cemented total joint arthroplasty (THA). However, the currently available materials based mainly on polymethylmethacrylate (PMMA) still encounter certain limitations, such as time-consuming polymerization, thermal and chemical necrosis and troublesome revision procedure. Here from an alternative way, we proposed for the first time to adopt the injectable alloy cement to address such tough issues through introducing its unique liquid-solid phase transition mechanism. A typical cement along this way is thus made of an alloy Bi/In/Sn/Zn with a specifically designed low melting point 57.5 °C, which enables its rapid molding into various desired shapes with high plasticity and ultimate metallic behaviors. The fundamental characteristics including the mechanical strength, biocompatibility and phase transition-induced thermal effects have been clarified to demonstrate the importance of such alloy as unconventional cement with favorable merits. In addition, we also disclosed its advantage as an excellent contrast agent for radiation imaging on the bone interior structure which is highly beneficial for guiding the surgery and monitoring the therapeutic effects. Particularly, the proposed alloy cement with reversible phase transition feature significantly simplifies the revision of the cement and prosthesis. This study opens the way for employing the injectable alloy materials as reversible bone cement to fulfill diverse clinical needs in the coming time. PMID:25239039

  19. Production of Thorium-229 at the ORNL High Flux Isotope Reactor

    SciTech Connect

    Boll, Rose Ann; Garland, Marc A; Mirzadeh, Saed

    2008-01-01

    The investigation of targeted cancer therapy using -emitters has developed considerably in recent years and clinical trials have generated promising results. In particular, the initial clinical trials for treatment of acute myeloid leukemia have demonstrated the effectiveness of the -emitter 213Bi in killing cancer cells [1]. Pre-clinical studies have also shown the potential application of both 213Bi and its 225Ac parent radionuclide in a variety of cancer systems and targeted radiotherapy [2]. Bismuth-213 is obtained from a radionuclide generator system from decay of the 10-d 225Ac parent, a member of the 7340-y 229Th chain. Currently, 233U is the only viable source for high purity 229Th; however, due to increasing difficulties associated with 233U safeguards, processing additional 233U is presently unfeasible. The recent decision to downblend and dispose of enriched 233U further diminished the prospects for extracting 229Th from 233U stock. Nevertheless, the anticipated growth in demand for 225Ac may soon exceed the levels of 229Th (~40 g or ~8 Ci; ~80 times the current ORNL 229Th stock) present in the aged 233U stockpile. The alternative routes for the production of 229Th, 225Ra and 225Ac include both reactor and accelerator approaches [3]. Here, we describe production of 229Th via neutron transmutation of 226Ra targets in the ORNL High Flux Isotope Reactor (HFIR).

  20. Preliminary radiological safety assessment for decommissioning of thoria dissolver of the ²³³U pilot plant, Trombay.

    PubMed

    Priya, S; Srinivasan, P; Gopalakrishnan, R K

    2012-01-01

    The thoria dissolver, used for separation of (233)U from reactor-irradiated thorium metal and thorium oxide rods, is no longer operational. It was decided to carry out assessment of the radiological status of the dissolver cell for planning of the future decommissioning/dismantling operations. The dissolver interiors are expected to be contaminated with the dissolution remains of irradiated thorium oxide rods in addition to some of the partially dissolved thoria pellets. Hence, (220)Rn, a daughter product of (228)Th is of major radiological concern. Airborne activity of thoron daughters (212)Pb (Th-B) and (212)Bi (Th-C) was estimated by air sampling followed by high-resolution gamma spectrometry of filter papers. By measuring the full-energy peaks counts in the energy windows of (212)Pb, (212)Bi and (208)Tl, concentrations of thoron progeny in the sampled air were estimated by applying the respective intrinsic peak efficiency factors and suitable correction factors for the equilibration effects of (212)Pb and (212)Bi in the filter paper during the delay between sampling and counting. Then the thoron working level (TWL) was evaluated using the International Commission on Radiological Protection (ICRP) methodology. Finally, the potential effective dose to the workers, due to inhalation of thoron and its progeny during dismantling operations was assessed by using dose conversion factors recommended by ICRP. Analysis of filter papers showed a maximum airborne thoron progeny concentration of 30 TWLs inside the dissolver. PMID:21447504

  1. Alterations in Amygdala Functional Connectivity Reflect Early Temperament

    PubMed Central

    Roy, Amy Krain; Benson, Brenda E.; Degnan, Kathryn A.; Perez-Edgar, Koraly; Pine, Daniel S.; Fox, Nathan A.; Ernst, Monique

    2014-01-01

    Behavioral inhibition (BI) is a temperament identified early in life that is associated with increased risk for anxiety disorders. Amygdala hyperresponsivity, found both in behaviorally inhibited and anxious individuals, suggests that amygdala dysfunction may represent a marker of anxiety risk. However, broader amygdala networks have not been examined in individuals with a history of childhood BI. This study uses resting state fMRI to assess amygdala intrinsic functional connectivity (iFC) in 38 healthy young adults (19 with a history of BI, 19 with no history of BI) selected from a longitudinal study. Centromedial, basolateral, and superficial amygdala iFCs were compared between groups and examined in relation to self-report measures of anxiety. Group differences were observed in amygdala iFC with prefrontal cortex, striatum, anterior insula, and cerebellum. Adults characterized with BI in childhood endorsed greater state anxiety prior to entering the scanner, which was associated with several of the group differences. Findings support enduring effects of BI on amygdala circuitry, even in the absence of current psychopathology. PMID:25261727

  2. L{alpha}, L{beta}, and L{gamma} x-ray production cross sections of Hf, Ta, W, Re, Os, Au, Pb, and Bi by electron impact: Comparison of distorted-wave calculations with experiment

    SciTech Connect

    Fernandez-Varea, Jose M.; Segui, Silvina; Dingfelder, Michael

    2011-02-15

    We study the emission of L{alpha}, L{beta}, and L{gamma} characteristic x rays by the impact of electrons on Hf, Ta, W, Re, Os, Au, Pb, and Bi atoms. To this end, ionization cross sections of the L{sub 1}, L{sub 2}, and L{sub 3} subshells of these atoms are calculated within the distorted-wave Born approximation. The considered energy interval spans from the ionization threshold up to 50 keV. Atomic relaxation parameters (i.e., Coster-Kronig and radiative transition probabilities, fluorescence yields, and emission rates) taken from the literature are then used to evaluate x-ray production cross sections. The theoretical predictions are compared with published experimental information. Good agreement is found for Ta, W, Os, Au, Pb, and Bi. In the case of Hf and Re, the measured cross sections are lower than the theoretical estimates by around 30%. The observed discrepancies might be attributed to the methods employed to correct the raw experimental data for the excess of detected characteristic x rays caused by the finite thickness of the sample's active layer and the presence of the thick substrate.

  3. Improved Performance of GaInNAs Solar Cells Grown by Molecular-Beam Epitaxy Using Increased Growth Rate Instead of Surfactants

    SciTech Connect

    Ptak, A. J.; France, R.; Jiang, C. S.; Romero, M. J.

    2009-01-01

    GaInNAs is potentially useful for increasing the conversion efficiency of multijunction solar cells if low photocurrents and photovoltages can be increased. Wide-depletion width devices generate significant photocurrents using an n-i-p structure grown by molecular-beam epitaxy, but these wide depletion widths are only realized in a region of parameter space that leads to rough surface morphologies. Surfactants are effective at reducing the surface roughness, but lead to increased defect densities and changes in the net acceptor or donor concentration. Here, we show that increasing the growth rate of GaInNAs solar cells leads to smooth surfaces without the use of a surfactant, even at high In compositions and substrate temperatures. No degradation in material quality is observed when increasing the growth rate from 1.5 to 3.0 {micro}m/h, but a shunt resistance does appear for the high-growth-rate samples. This shunt is attributed to increased spitting of the Ga cell, leading to an increase in the oval defect density, at the higher effusion cell temperatures used to achieve high growth rates. As with the case of Bi in GaInNAs, increased growth rates also appear to increase the net donor concentration, but it is not clear if these effects have the same cause.

  4. Influence of convection on eutectic microstructure

    NASA Technical Reports Server (NTRS)

    Baskaran, V.; Eisa, G. F.; Wilcox, W. R.

    1985-01-01

    When the MnBi-Bi eutectic is directionally solidified, it forms fibers of MnBi in a matrix of bismuth. When the material solidified in space at rates of 30 and 50 cm/hr, the average fiber spacing lambda was about one half of the value obtained in cases in which the same material solidified on earth. Neither an altered temperature gradient nor a fluctuating freezing rate are apparently responsible for the change in lambda, and the possibility is studied that natural convection increases lambda on earth by perturbing the compositional field in the melt ahead of the growing solid. A theoretical analysis is conducted along with some experiments. On the basis of the theoretical results for lamellar growth, it is concluded that the spacing lambda increases with increasing stirring, especially at small freezing rates. The experiments indicate that at low growth rates the cross-sectional area of the MnBi blades increases with increased stirring and with decreased growth rate.

  5. Quantitative imaging analysis and investigation of transmission loss in PbF2 crystals by laser ablation-inductively coupled plasma-mass spectrometry method.

    PubMed

    Zhang, Guoxia; Wang, Zheng; Li, Qing; Zhou, Hui; Zhu, Yan; Du, Yiping

    2016-07-01

    We developed a procedure for preparing matrix-matched calibration standards for the quantitative imaging of multiple trace elements in PbF2 crystals by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). In this facile approach, PbO powder was employed as the matrix with the addition of a series of standard solutions, followed by drying and tableting, for determining the concentrations of (24)Mg, (27)Al, (89)Y, (103)Rh, (133)Cs, (175)Lu and (209)Bi in transparent samples (with homogeneous element distribution). (206)Pb was chosen as the internal standard and the correlation coefficients of the calibration curves for all elements ranged from 0.9987 to 0.9999 after internal standard correction. The analysis showed good agreement with the results observed by established ICP-MS methods, following acid dissolution of the samples. Finally, the element distributions and transmission curves of a PbF2 sample with non-transparent and transparent sections were visualized. The distribution images, in conjunction with the transmission curves, suggested that the enrichment of Mg, Al, Rh, Cs, and Bi atoms in the non-transparent section of the sample could explain the loss in transmission observed for that section. PMID:27154704

  6. Robust surface state transport in thin bismuth nanoribbons

    NASA Astrophysics Data System (ADS)

    Ning, Wei; Kong, Fengyu; Han, Yuyan; Du, Haifeng; Yang, Jiyong; Tian, Mingliang; Zhang, Yuheng

    2014-11-01

    While a two-dimensional (2D) metallic surface state in bismuth has been proposed, experimental 2D evidence of quantum transport, e.g., angular dependent Shubnikov-de Haas (SdH) oscillations is still lacking. Here, we report the angular-dependent magnetoresistance measurements in single-crystal Bi nanoribbons, and found that both the low-field weak antilocalization behavior and the high-field angle-dependent SdH oscillations follow exactly the 2D character, indicative of the 2D metallic surface states which dominate the transport properties of thin Bi nanoribbons. Moreover, by controllable exposing the ribbons to ambient environment (1 atm and room temperature), the metallic surface states were found to be robust to the oxidation although the carrier density in the surface states are modified after the exposures. These results suggest that the metallic surface states in Bi nanoribbons should be topologically protected which can provide key information in understanding the surface properties of Bi in nanometer scale.

  7. A computational study on brain tissue under blast: primary and tertiary blast injuries.

    PubMed

    Rezaei, A; Salimi Jazi, M; Karami, G; Ziejewski, M

    2014-08-01

    In this paper, a biomechanical study of a human head model exposed to blast shock waves followed by a blunt impact with the surface of the enclosing walls of a confined space is carried out. Under blast, the head may experience primary blast injury (PBI) due to exposure to the shockwaves and tertiary blast injury (TeBI) due to a possible blunt impact. We examine the brain response data in a deformable finite element head model in terms of the inflicted stress/pressure, velocity, and acceleration on the brain for several blast scenarios with different intensities. The data will be compared for open space and confined spaces. Following the initial impact of the shock front in the confined space, one can see the fluctuations in biomechanical data due to wave reflections. Although the severity of the PBI and TeBI is dependent on the situation, for the cases studied here, PBI is considerably more pronounced than TeBI in confined spaces. PMID:24515869

  8. Domain structure and magnetic resonance studies of ferroelastic BiVO4 revisited

    NASA Astrophysics Data System (ADS)

    Choh, Sung Ho; Jang, Min Su

    2016-04-01

    Bismuth vanadate (BiVO4) is a ferroelastic material undergoing a reversible second order phase transition at 528 K(T c) between the tetragonal and monoclinic structure. There have been experimental studies on the incommensurate domain wall (W‧) which reported different orientation angles. In order to clarify this we have tried to calculate it numerically in terms of lattice constants above and below T c by employing the theory of Sapriel, and obtained it to be either 35.9° or 54.1°. It also turns out that the shear strain (S 21) in the ferroelastic phase depends on the crystal growing condition. The remaining internal stress appears to be responsible for the formation of W‧ wall. The host atom nuclear magnetic resonance and the S-state impurity electron magnetic resonance are also reviewed. The nuclear electric quadrupole interaction of 51V and 209Bi in BiVO4 was evaluated in terms of the point charge model based on the crystal structure. The result of electric field gradient tensor turns out to be reasonable with experimental values. The zero-field splitting tensor of Mn2+, Fe3+ and Gd3+ are also compared, and the deduced local environment of these ions in the host are confirmed. Finally the second-order phase transition according to the Landau’s framework is found in this crystal from the temperature dependence of magnetic resonance parameters. Supported by The National Academy of Sciences, Republic of Korea (2014) through SHC.

  9. Dorsal prefrontal cortical serotonin 2A receptor binding indices are differentially related to individual scores on harm avoidance.

    PubMed

    Baeken, Chris; Bossuyt, Axel; De Raedt, Rudi

    2014-02-28

    Although the serotonergic system has been implicated in healthy as well as in pathological emotional states, knowledge about its involvement in personality is limited. Earlier research on this topic suggests that post-synaptic 5-HT2A receptors could be involved in particular in frontal cortical areas. In drug-naïve healthy individuals, we examined the relationship between these 5-HT2A receptors and the temperament dimension harm avoidance (HA) using 123I-5-I-R91150 single photon emission computed tomography (SPECT). HA is a personality feature closely related to stress, anxiety and depression proneness, and it is thought to be mediated by the serotonergic system. We focused on the prefrontal cortices as these regions are frequently implicated in cognitive processes related to a variety of affective disorders. We found a positive relationship between dorsal prefrontal cortical (DPFC) 5-HT2A receptor binding indices (BI) and individual HA scores. Further, our results suggest that those individuals with a tendency to worry or to ruminate are particularly prone to display significantly higher 5-HT2A receptor BI in the left DPFC. Although we only examined psychologically healthy individuals, this relationship suggests a possible vulnerability for affective disorders. PMID:24412555

  10. Adsorptional photocatalytic mineralization of oxytetracycline and ampicillin antibiotics using Bi2O3/BiOCl supported on graphene sand composite and chitosan.

    PubMed

    Priya, Bhanu; Raizada, Pankaj; Singh, Nahar; Thakur, Pankaj; Singh, Pardeep

    2016-10-01

    In present study, heterojunctioned Bi2O3/BiOCl (BO/BOC) was synthesized via in situ chemical reduction and oxidation of BiOCl nanoplates. BiOCl was reduced to metallic Bi in KHB4 solution followed by oxidation in H2O2 solution to produce BO/BOC. The BO/BOC was supported over graphene sand composite and also on chitosan using wet impregnation method to report BO/BOC/GSC and BO/BOC/CT nanocomposite. The morphology and compositional characteristics of BO/BOC/GSC and BO/BOC/CT were investigated by FESEM, TEM, HRTEM, FTIR, XRD, EDX, RAMAN, BET and UV-visible diffuse reflectance spectral analysis. The photocatalytic activity of BO/BOC/GSC and BO/BOC/CT was performed for mineralization of ampicillin (AMP) and oxytetracycline (OTC) antibiotics under solar light. The adsorption process had significant effect on photodegradation of AMP and OTC. The adsorption of both OTC and AMP onto BO/BOC/GSC and BO/BOC/CT followed pseudo second order kinetics. Simultaneous adsorption and degradation process (A+P) resulted in higher degradation rate of investigated antibiotics. The applicability of power law model indicates the intricacies of mineralization process. During A+P process, OTC and AMP were mineralized to CO2·H2O, NO3(-) and SO4(2-) ions. Both BO/BOC/GSC and BO/BOC/CT exhibited significant recycle efficiency. PMID:27393889

  11. Burn injury induces histopathological changes and cell proliferation in liver of rats

    PubMed Central

    Bortolin, Jeferson André; Quintana, Hananiah Tardivo; Tomé, Tabata de Carvalho; Ribeiro, Flavia Andressa Pidone; Ribeiro, Daniel Araki; de Oliveira, Flavia

    2016-01-01

    AIM: To investigate effects of severe burn injury (BI) in rat liver through the histopathological and inflammatory markers analysis. METHODS: Forty-two male Wistar rats were distributed into two groups, control (C) and subjected to scald BI (SBI). The animals were euthanized one, four and 14 d post sham or 45% of the total body surface BI. Liver fragments were submitted to histopathological, morphoquantitative (hepatocyte area and cell density), ciclooxigenase-2 (COX-2) immunoexpression, and gene expression [real-time polymerase chain reaction for tumor necrosis factor (TNF)-α, inducible nitric oxide synthase (iNOS) and caspase-3] methods. RESULTS: Histopathological findings showed inflammatory process in all periods investigated and hepatocyte degeneration added to increased amount of connective tissue 14 d post injury. Hepatocyte area, the density of binucleated hepatocytes and density of sinusoidal cells of SBI groups were increased when compared with control. COX-2 immunoexpression was stronger in SBI groups. No differences were found in TNF-α, iNOS and caspase-3 gene expression. CONCLUSION: BI induces histopathological changes, upregulation of COX-2 immunoexpression, and cell proliferation in liver of rats. PMID:26962398

  12. Unusual 232Th and 238U contamination on some road surfaces in Taoyuan, Taiwan.

    PubMed

    Chang, W P; Nabyvanets, Y B; Jen, M H

    2001-06-01

    At least eight bustling streets or approximately 3-5% of all the road surface of civilian utility in the downtown area of Taoyuan City, Taiwan, were inadvertently found to contain unusual levels of radioactivity during a routine environmental radiation surveillance in mid-1994. Crushed rock debris and coarse sands separated from the asphalt pavement were identified to be the source of excessive radioactivity. By employing gamma spectrometry, we have measured 232Th activity (via 228Ac) and mU activity (via 214Bi) in some of the samples to be up to about 4,000 and 1,000 Bq kg(-1), respectively. The dose rate on the road surface reached about 1.3 microSv h(-1), as compared with the background level of 0.08 microSv h(-1) in much of Taiwan. This unusual radioactivity was due to accidental mixing of road construction materials with materials enriched 232Th and 238U. PMID:11388731

  13. Extended magnetic exchange interactions in the high-temperature ferromagnet MnBi

    NASA Astrophysics Data System (ADS)

    Williams, T. J.; Taylor, A. E.; Christianson, A. D.; Hahn, S. E.; Fishman, R. S.; Parker, D. S.; McGuire, M. A.; Sales, B. C.; Lumsden, M. D.

    2016-05-01

    The high-temperature ferromagnet MnBi continues to receive attention as a candidate to replace rare-earth-containing permanent magnets in applications above room temperature. This is due to a high Curie temperature, large magnetic moments, and a coercivity that increases with temperature. The synthesis of MnBi also allows for crystals that are free of interstitial Mn, enabling more direct access to the key interactions underlying the physical properties of binary Mn-based ferromagnets. In this work, we use inelastic neutron scattering to measure the spin waves of MnBi in order to characterize the magnetic exchange at low temperature. Consistent with the spin reorientation that occurs below 140 K, we do not observe a spin gap in this system above our experimental resolution. A Heisenberg model was fit to the spin wave data in order to characterize the long-range nature of the exchange. It was found that interactions up to sixth nearest neighbor are required to fully parametrize the spin waves. Surprisingly, the nearest-neighbor term is antiferromagnetic, and the realization of a ferromagnetic ground state relies on the more numerous ferromagnetic terms beyond nearest neighbor, suggesting that the ferromagnetic ground state arises as a consequence of the long-ranged interactions in the system.

  14. Extended magnetic exchange interactions in the high-temperature ferromagnet MnBi

    DOE PAGESBeta

    Christianson, Andrew D.; Hahn, Steven E.; Fishman, Randy Scott; Parker, David S.; McGuire, Michael A.; Sales, Brian C.; Lumsden, Mark D.; Williams, T. J.; Taylor, A. E.

    2016-05-09

    Here, the high-temperature ferromagnet MnBi continues to receive attention as a candidate to replace rare-earth-containing permanent magnets in applications above room temperature. This is due to a high Curie temperature, large magnetic moments, and a coercivity that increases with temperature. The synthesis of MnBi also allows for crystals that are free of interstitial Mn, enabling more direct access to the key interactions underlying the physical properties of binary Mn-based ferromagnets. In this work, we use inelastic neutron scattering to measure the spin waves of MnBi in order to characterize the magnetic exchange at low temperature. Consistent with the spin reorientationmore » that occurs below 140~K, we do not observe a spin gap in this system above our experimental resolution. A Heisenberg model was fit to the spin wave data in order to characterize the long-range nature of the exchange. It was found that interactions up to sixth nearest neighbor are required to fully parameterize the spin waves. Surprisingly, the nearest-neighbor term is antiferromagnetic, and the realization of a ferromagnetic ground state relies on the more numerous ferromagnetic terms beyond nearest neighbor, suggesting that the ferromagnetic ground state arises as a consequence of the long-ranged interactions in the system.« less

  15. Posttraumatic stress disorder symptoms following media exposure to tragic events: impact of 9/11 on children at risk for anxiety disorders.

    PubMed

    Otto, Michael W; Henin, Aude; Hirshfeld-Becker, Dina R; Pollack, Mark H; Biederman, Joseph; Rosenbaum, Jerrold F

    2007-01-01

    With the extensive media coverage on September 11, 2001, adults and children indirectly witnessed the terrorist attacks leading to the deaths of almost 3,000 people. An ongoing longitudinal study provided the opportunity to examine pre-event characteristics and the impact of this media exposure. We assessed symptoms of PTSD in 166 children and 84 mothers who had no direct exposure to the 9/11 attacks. The sample included children who had parents with or without anxiety and mood disorders, and who had been assessed for the presence or absence of temperamental behavioral inhibition (BI). We found a 5.4 percent rate of symptomatic PTSD in response to 9/11 in children and 1.2 percent in their mothers. Children's identification with victims of the attack, and for younger children, the amount of television viewing predicted increased risk of PTSD symptoms. Parental depression was associated with higher symptoms, and pre-event levels of family support was associated with a lower risk for PTSD symptoms. BI in children was also linked to lower rates of PTSD symptoms, suggesting that a cautious and fearful approach to novelty may offer protection against exposure to media-based traumatic images. Media viewing of tragic events is sufficient to produce PTSD symptoms in vulnerable populations such as children. Given the links between PTSD symptoms and viewing habits, parental monitoring of media exposure may be important for younger children. PMID:17276653

  16. The Abundance and Isotopic Composition of Hg in Extraterrestrial Materials

    NASA Technical Reports Server (NTRS)

    Lauretta, D. S.

    2004-01-01

    During the past three year grant period we made excellent progress in our study of the abundances and isotopic compositions of Hg and other volatile trace elements in extraterrestrial materials. As part of my startup package I received funds to construct a state-of-the-art experimental facility to study gas-solid reaction kinetics. Much of our effort was spent developing the methodology to measure the abundance and isotopic composition of Hg at ultratrace levels in solid materials. In our first study, the abundance and isotopic composition of Hg was determined in bulk samples of the Murchison (CM) and Allende (CV) carbonaceous chondrites. We have continued our study of mercury in primitive meteorites and expanded the suite of meteorites to include other members of the CM and CV chondrite group as well as CI and CO chondrites. Samples of the CI chondrite Orgueil, the CM chondrites Murray, Nogoya, and Cold Bokkeveld, the CO chondrites Kainsaz, Omans, and Isna, and the CV chondrites Vigarano, Mokoia, and Grosnaja were tested. We have developed a thermal analysis ICP-MS technique and applied it to the study of a suite of thermally labile elements (Zn, As, Se, Cd, In, Sn, Sb, Te, Hg, Au, Tl, Pb, and Bi) in geologic materials as well.

  17. Investigation of a sterilization system using active oxygen species generated by ultraviolet irradiation.

    PubMed

    Yoshino, Kiyoshi; Matsumoto, Hiroyuki; Iwasaki, Tatsuyuki; Kinoshita, Shinobu; Noda, Kazutoshi; Oya, Kei; Iwamori, Satoru

    2015-01-01

    We have been investigating an advanced sterilization system that employs active oxygen species (AOS). We designed the sterilization equipment, including an evacuation system, which generates AOS from pure oxygen gas using ultraviolet irradiation, in order to study the conditions necessary for sterilization in the system's chamber. Using Geobachillus stearothermophilus spores (10(6) CFU) in a sterile bag as a biological indicator (BI) in the chamber of the AOS sterilization apparatus, we examined the viability of the BI as a function of exposure time, assessing the role of the decompression level in the sterilization performance. We found that the survival curves showed exponential reduction, and that the decompression level did not exert a significant influence on the survival curve. Subsequently, we investigated the sterilization effect as influenced by the spatial and environmental temperature variation throughout the chamber, and found that the sterilization effect varied with position, due to the varying environmental temperature in the respective areas. We confirmed that temperature is one of the most important factors influencing sterilization in the chamber, and estimated the temperature effect on the distribution of atomic oxygen concentration, using the quartz crystal microbalance (QCM) method with fluorocarbon thin film prepared by radio frequency sputtering. PMID:25817808

  18. Method and apparatus for recirculation with control of synchrotron radiation

    DOEpatents

    Douglas, David R.; Tennant, Christopher

    2016-08-02

    A method for controlling beam quality degradation from ISR and CSR and stabilizing the microbunching instability (.mu.BI) in a high brightness electron beam. The method includes providing a super-periodic second order achromat line with each super period being individually linearly achromatic and isochronous, setting individual superperiod tunes to rational fractions of an integer (such as 4.sup.th or 6.sup.th integers), setting individual bend angles to be as small as practical to reduce driving terms due to dispersion and dispersive angle, and setting bend radii as large enough to suppress ISR but not negatively affect the radial dependence of CSR. The method includes setting the structure of the individual superperiods to minimize bend plane beam envelope values in the dipoles to reduce betatron response to a CSR event at a dispersed location, increasing beam angular divergence, and creating dispersion nodes in the dipoles to similarly reduce response to CSR events, and limit R.sub.56 modulation in order to mitigate .mu.BI.

  19. Titanium oxide:fullerene composite films as electron collector layer in organic solar cells and the use of an easy-deposition cathode

    NASA Astrophysics Data System (ADS)

    Pérez-Gutiérrez, Enrique; Maldonado, José-Luis; Nolasco, Jairo; Ramos-Ortíz, Gabriel; Rodríguez, Mario; Torre, Ulises Mendoza-De la; Meneses-Nava, Marco-Antonio; Barbosa-García, Oracio; García-Ortega, Héctor; Farfán, Norberto; Granados, Giovana; Santillan, Rosa; Juaristi, Eusebio

    2014-06-01

    Here is reported the use of a titanium oxide:fullerene (TiOx:PC71BM) composite film as electron collector layer in organic photovoltaic devices (OPV cells). OPV cells were fabricated under the bulk heterojunction architecture: the active layer was a blend of either the photoconductor polymer MEH-PPV or P3HT with the fullerene derivative PC71BM. As cathode the eutectic alloy of Bi, In and Sn, known as Field’s metal, was used. The melting point of this alloy is above 62 °C, which makes it suitable for a vacuum-free deposition process and easy and fast device test. Cell fabrication and testing were carried out at normal room conditions. For OPV cells based on MEH-PPV, the composite thin electron collector layer improved the power conversion efficiency (η) from 1.12% to 2.07%, thus the η increase was about 85%. Meanwhile, for devices based on P3HT the use of the composite film improved the photocurrent in almost 1 mA/cm2 and the efficiency slightly increase from 2.48% to 2.68%.

  20. Spectroscopy of 214Bi and systematics of 210,212,214Pb(0+) long->β-210,212,214Bi(0-)

    NASA Astrophysics Data System (ADS)

    Berant, Z.; Schuhmann, R. B.; Alburger, D. E.; Chou, W. T.; Gill, R. L.; Warburton, E. K.; Wesselborg, C.

    1991-04-01

    Experiments designed to provide more information on the spectroscopy of 214Bi, and on 214Pb(β-)214Bi in particular, were undertaken because of interest in first-forbidden β decay in the lead region. The experiments consisted of γ-γ coincidences and angular correlations, conversion electron measurements, level lifetime determinations, and precision γ-ray energy measurements. The 352-keV level of 214Bi was found to be a strong candidate (and the only candidate) for the 0-1 state. Recent additions to the 214Pb decay scheme are confirmed by γ-γ coincidence measurements. A careful evaluation of the 214Bi level scheme is made with emphasis on separating experimentally based conclusions from speculations based on systematics and other ``weak'' arguments. Shell-model calculations of the spectroscopy of 210,212Bi and 210,212Pb(β-)210,212Bi were performed using a modification of the Kuo-Herling realistic interaction. These calculations and a generalized seniority model provide a basis for an examination of the systematics of the A=210, 212, 214 spectroscopy and β decay. The generalized seniority model is found to be a quite good approximation which provides a quantitative understanding of the 214Pb decay rates.

  1. Thromboxane synthase suppression induces lung cancer cell apoptosis via inhibiting NF-{kappa}B

    SciTech Connect

    Leung, Kin Chung; Li, Ming-Yue; Leung, Billy C.S.; Hsin, Michael K.Y.; Mok, Tony S.K.; Underwood, Malcolm J.; Chen, George G.

    2010-12-10

    Accumulating evidence shows that the inhibition of thromboxane synthase (TXS) induced apoptosis in cancer cells. TXS inhibitor 1-Benzylimidzole (1-BI) can trigger apoptosis in lung cancer cells but the mechanism is not fully defined. In this study, lung cancer cells were treated with 1-BI. In this study, the level of reactive oxygen species (ROS) was measured and NF-{kappa}B activity was determined in human lung cancer cells. The roles of ROS and NF-{kappa}B in 1-BI-mediated cell death were analyzed. The results showed that 1-BI induced ROS generation but decreased the activity of NF-{kappa}B by reducing phosphorylated I{kappa}B{alpha} (p-I{kappa}B{alpha}) and inhibiting the translocation of p65 into the nucleus. In contrast to 1-BI, antioxidant N-acetyl cysteine (NAC) stimulated cell proliferation and significantly protected the cells from 1-BI-mediated cell death by neutralizing ROS. Collectively, apoptosis induced by 1-BI is associated with the over-production of ROS and the reduction of NF-{kappa}B. Antioxidants can significantly block the inhibitory effect of 1-BI.

  2. The Surface Structure of Liquid Metals and Alloys

    NASA Astrophysics Data System (ADS)

    Pershan, Peter

    2004-03-01

    X-ray scattering of the surface structure of liquid metals and liquid metal alloys will be discussed. We will report observations of the theoretically predicted surface induced atomic layering; however, quantitative interpretation of the local surface structure factor requires that the Debye-Waller effect associated with thermal capillary waves be accounted for. We will explain how that is done. Results that will be described for surfaces that exhibit simple layering , such as Ga, In and K, will be contrasted with anomalous layering that is observed for Sn. In addition data on the surfaces of alloys such as GaBi, InBi, AuGe and AuSi will be presented This work is supported by DE-FG02-88-ER45379 and DMR-0124936. Experiments at BNL and CMC-Cat at the APS are supported by DE-AC02-98CH10886. Experiments at ChemMatCars at the APS are supported by NSF/DOE grant CHE0087817.

  3. Predicted Growth of Two-Dimensional Topological Insulator Thin Films of III-V Compounds on Si(111) Substrate.

    PubMed

    Yao, Liang-Zi; Crisostomo, Christian P; Yeh, Chun-Chen; Lai, Shu-Ming; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2015-01-01

    We have carried out systematic first-principles electronic structure computations of growth of ultrathin films of compounds of group III (B, Al, In, Ga, and Tl) with group V (N, P, As, Sb, and Bi) elements on Si(111) substrate, including effects of hydrogenation. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs, and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN, and TlBi which can be driven into the nontrivial phase via strain. A large band gap of 134 meV is identified in hydrogenated 2 BL film of InBi. One and two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates. PMID:26537227

  4. Predicted Growth of Two-Dimensional Topological Insulator Thin Films of III-V Compounds on Si(111) Substrate

    NASA Astrophysics Data System (ADS)

    Yao, Liang-Zi; Crisostomo, Christian P.; Yeh, Chun-Chen; Lai, Shu-Ming; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2015-11-01

    We have carried out systematic first-principles electronic structure computations of growth of ultrathin films of compounds of group III (B, Al, In, Ga, and Tl) with group V (N, P, As, Sb, and Bi) elements on Si(111) substrate, including effects of hydrogenation. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs, and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN, and TlBi which can be driven into the nontrivial phase via strain. A large band gap of 134 meV is identified in hydrogenated 2 BL film of InBi. One and two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates.

  5. Raman probe of new laser materials GaAs1-xBixand InAs1-xBix

    NASA Astrophysics Data System (ADS)

    Verma, Prabhat; Herms, Martin; Irmer, Gert; Yamada, Masayoshi; Okamoto, Hiroshi; Oe, Kunishige

    2000-03-01

    Inclusion of a small amount of Bi in InAs and GaAs changes the temperature dependent behavior of the band gap. Both InAs1- xBix and GaAs1-xBix tend to have temperature insensitive band gap with increasing Bi content. Raman scattering has been performed on the epilayers of InAs1- xBix and GaAs1-xBix compounds grown by MOVPE technique for varying Bi content. Good single crystalline growth with spatial homogeneity was confirmed using micro- Raman technique. Vibrational modes of InBi and GaBi were observed in the two materials, respectively. In addition, vibrational modes corresponding to Bi and phonon-plasmon coupled modes were also observed. Experimental results indicate that Bi atoms homogeneously replace some of the As atoms in both InAs as well as in GaAs to provide good crystalline structures of InAs1-xBix and GaAs1- xBix compounds, respectively.

  6. Time series regression and ARIMAX for forecasting currency flow at Bank Indonesia in Sulawesi region

    NASA Astrophysics Data System (ADS)

    Suharsono, Agus; Suhartono, Masyitha, Aulia; Anuravega, Arum

    2015-12-01

    The purpose of the study is to forecast the outflow and inflow of currency at Indonesian Central Bank or Bank Indonesia (BI) in Sulawesi Region. The currency outflow and inflow data tend to have a trend pattern which is influenced by calendar variation effects. Therefore, this research focuses to apply some forecasting methods that could handle calendar variation effects, i.e. Time Series Regression (TSR) and ARIMAX models, and compare the forecast accuracy with ARIMA model. The best model is selected based on the lowest of Root Mean Squares Errors (RMSE) at out-sample dataset. The results show that ARIMA is the best model for forecasting the currency outflow and inflow at South Sulawesi. Whereas, the best model for forecasting the currency outflow at Central Sulawesi and Southeast Sulawesi, and for forecasting the currency inflow at South Sulawesi and North Sulawesi is TSR. Additionally, ARIMAX is the best model for forecasting the currency outflow at North Sulawesi. Hence, the results show that more complex models do not neccessary yield more accurate forecast than the simpler one.

  7. miR-92b regulates glioma cells proliferation, migration, invasion, and apoptosis via PTEN/Akt signaling pathway.

    PubMed

    Song, Hang; Zhang, Yao; Liu, Na; Wan, Chao; Zhang, Dongdong; Zhao, Sheng; Kong, Yan; Yuan, Liudi

    2016-06-01

    Glioblastoma (GBM) is a highly invasive malignant primary brain tumor with neoplastic growth. Despite the progresses made in surgery, chemotherapy, and radiation in recent decade, the prognosis of patients with gliomas remains poor and the average survival time of patients suffering from glioblastoma is still short. As a potential therapy strategy, microRNAs have been considered as new targets for possible cancer treatment. In this study, we found that the miR-92b inhibitors (miR-92b-I) could inhibit the proliferation, migration, invasion, and promote the apoptosis of glioma cells. As a predicted target of miR-92b, phosphatase and tensin homolog (PTEN), also elevated at both mRNA and protein levels. Moreover, the Akt phosphorylation was consistently inhibited. The rescue experiment with miR-92b and PTEN double knockdown resulted in partial reversion of miR-92b-I-induced phenotypes. Taken together, our findings indicated that miR-92b-I could restrain the proliferation, invasion, migration, and stimulate apoptosis of glioma cells by targeting PTEN/Akt signaling pathway. Further investigations will focus on antitumor effect of miR‑92b-I in glioma treatment. PMID:26893028

  8. Predicted Growth of Two-Dimensional Topological Insulator Thin Films of III-V Compounds on Si(111) Substrate

    DOE PAGESBeta

    Yao, Liang-Zi; Crisostomo, Christian P.; Yeh, Chun-Chen; Lai, Shu-Ming; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2015-11-05

    We have carried out systematic first-principles electronic structure computations of growth of ultrathin films of compounds of group III (B, Al, In, Ga, and Tl) with group V (N, P, As, Sb, and Bi) elements on Si(111) substrate, including effects of hydrogenation. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs, and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN, and TlBi which can be driven into the nontrivial phase via strain. A large band gap of 134 meV is identified in hydrogenated 2 BL film of InBi. One andmore » two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates.« less

  9. Quantum oscillations in the heavy-fermion compound YbPtBi

    DOE PAGESBeta

    Mun, E.; Bud'ko, S. L.; Lee, Y.; Martin, C.; Tanatar, M. A.; Prozorov, R.; Canfield, P. C.

    2015-08-01

    We present quantum oscillations observed in the heavy-fermion compound YbPtBi in magnetic fields far beyond its field-tuned, quantum critical point. Quantum oscillations are observed in magnetic fields as low as 60 kOe at 60 mK and up to temperatures as high as 3 K, which confirms the very high quality of the samples as well as the small effective mass of the conduction carriers far from the quantum critical point. Although the electronic specific heat coefficient of YbPtBi reaches ~7.4 J/molK2 in zero field, which is one of the highest effective mass values among heavy-fermion systems, we suppress it quicklymore » by an applied magnetic field. The quantum oscillations were used to extract the quasiparticle effective masses of the order of the bare electron mass, which is consistent with the behavior observed in specific heat measurements. Furthermore, such small effective masses at high fields can be understood by considering the suppression of Kondo screening.« less

  10. Quantum oscillations in the heavy-fermion compound YbPtBi

    SciTech Connect

    Mun, E.; Bud'ko, S. L.; Lee, Y.; Martin, C.; Tanatar, M. A.; Prozorov, R.; Canfield, P. C.

    2015-08-01

    We present quantum oscillations observed in the heavy-fermion compound YbPtBi in magnetic fields far beyond its field-tuned, quantum critical point. Quantum oscillations are observed in magnetic fields as low as 60 kOe at 60 mK and up to temperatures as high as 3 K, which confirms the very high quality of the samples as well as the small effective mass of the conduction carriers far from the quantum critical point. Although the electronic specific heat coefficient of YbPtBi reaches ~7.4 J/molK2 in zero field, which is one of the highest effective mass values among heavy-fermion systems, we suppress it quickly by an applied magnetic field. The quantum oscillations were used to extract the quasiparticle effective masses of the order of the bare electron mass, which is consistent with the behavior observed in specific heat measurements. Furthermore, such small effective masses at high fields can be understood by considering the suppression of Kondo screening.

  11. Assessment of the Effects of Rehabilitation After Cerebrovascular Accident in Patients with Diabetes Mellitus and Hypertension as Risk Factors

    PubMed Central

    Tanovic, Edina; Selimovic, Senad; Tanovic, Haris

    2014-01-01

    ABSTRACT Aim: The aim of this study is to evaluate the results of rehabilitation, to determine the prevalence of major risk factors in cerebrovascular accident and their consequences, as well as to propose measures and procedures that will affect the better rehabilitation. Methods: The survey analyzed: age, sex, duration of rehabilitation, activities in daily life through the Barthel index at admission and at discharge, presence of risk factors HTA and DM. The study included a total of 116 patients, the majority of patients are older than 61 years. We had 49% of male patients and 51% of female patients and they spent 31-40 days at the rehabilitation. Results: The most common risk factor is HTA (83%) and diabetes (33%). Most of the patients at admission had a BI from 0 to 4 (32.7%), and at discharge BI in the range 17-20 (36.2%). Statistical analysis shows that there is a statistically significant correlation between the BI at admission, BI at discharge and risk factors of HTA and diabetes mellitus. Conclusions: the rehabilitation results in most patients is good results of rehabilitation. The most important risk factors in patients are HTA, DM and directly affect on results of rehabilitation. For the better results we should have energetic fight against risk factors for HTA and DM through primary and secondary prevention and patient education about early detection and treatment of these risk factors. PMID:24937938

  12. Predicted Growth of Two-Dimensional Topological Insulator Thin Films of III-V Compounds on Si(111) Substrate

    SciTech Connect

    Yao, Liang-Zi; Crisostomo, Christian P.; Yeh, Chun-Chen; Lai, Shu-Ming; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2015-11-05

    We have carried out systematic first-principles electronic structure computations of growth of ultrathin films of compounds of group III (B, Al, In, Ga, and Tl) with group V (N, P, As, Sb, and Bi) elements on Si(111) substrate, including effects of hydrogenation. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs, and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN, and TlBi which can be driven into the nontrivial phase via strain. A large band gap of 134 meV is identified in hydrogenated 2 BL film of InBi. One and two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates.

  13. Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering.

    PubMed

    Çınar, Simge; Tevis, Ian D; Chen, Jiahao; Thuo, Martin

    2016-01-01

    Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate ('/' = physisorbed, '-' = chemisorbed), from molten Field's metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity. PMID:26902483

  14. A Step in Between: [Sn3Bi3](5-) and Its Structural Relationship to [Sn3Bi5](3-) and [Sn4Bi4](4.).

    PubMed

    Friedrich, Ute; Korber, Nikolaus

    2016-08-01

    Extraction of "RbSnBi" in liquid ammonia yielded the cluster anion [Sn3Bi5](3-), which could be crystallized in the compound [Rb@[2.2.2]crypt]3[Sn3Bi5]⋅8.87 NH3. This anion is found to be derived from the formerly reported [Sn4Bi4](4-) by the formal substitution of one tin atom by bismuth. In contrast, the extraction of "RbSn2/Rb3Bi2" in liquid ammonia yielded the anion [Sn3Bi3](5-) in the compound Rb6[Sn3Bi3][Sn4]1/4⋅6.75 NH3. The structural correlation of the two novel clusters indicates that [Sn3Bi3](5-) might be an intermediate of the reaction pathway to [Sn3Bi5](3-) and [Sn4Bi4](4-). Each cluster is investigated by means of the electron localization function and further characterization was performed by using ESI-MS. PMID:27547638

  15. Characteristics of InGaAsBi with various lattice mismatches on InP substrate

    NASA Astrophysics Data System (ADS)

    Chen, X. Y.; Gu, Y.; Zhang, Y. G.; Xi, S. P.; Du, B.; Ma, Y. J.; Ji, W. Y.; Shi, Y. H.

    2016-07-01

    To develop bismuth-containing infrared optoelectronic devices, InGaAsBi/InP films with different lattice mismatches have been investigated. The lattice mismatch was tailored by changing the Bi content in conjunction with the In content simultaneously. X-ray diffraction analysis revealed that alloy lattice constants have been extended positively by incorporation of Bi into the crystal lattice. Electrical and optical characteristics were investigated by Hall-effect, optical absorption and photoluminescence measurements. A bandgap shrinking of about 56.4 meV/Bi% was deduced by X-ray diffraction and optical absorption measurements. From the excitation dependent photoluminescence measurement at 10 K, the donor-acceptor pair emissions were inferred for samples containing moderate and high levels of Bi. The temperature dependence of the PL peak energy is as small as 0.06 meV/K in In0.5Ga0.5As0.987Bi0.013, which is fairly low compared with that of In0.5Ga0.5As.

  16. The Karlsruhe Astrophysical Database of Nucleosynthesis in Stars Project – Status and Prospects

    SciTech Connect

    Dillmann, I.; Szücs, T.; Plag, R.; Fülöp, Z.; Käppeler, F.; Mengoni, A.; Rauscher, T.

    2014-06-15

    The KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars) project is an astrophysical online database for cross sections relevant for nucleosynthesis in the s process and the γ process. The s-process database ( (http://www.kadonis.org)) was started in 2005 and is presently facing its 4th update (KADoNiS v1.0). The γ-process database (KADoNiS-p, (http://www.kadonis.org/pprocess)) was recently revised and re-launched in March 2013. Both databases are compilations for experimental cross sections with relevance to heavy ion nucleosynthesis. For the s process recommended Maxwellian averaged cross sections for kT=5−100 keV are given for more than 360 isotopes between {sup 1}H and {sup 210}Bi. For the γ-process database all available experimental data from (p,γ),(p,n),(p,α),(α,γ),(α,n), and (α,p) reactions between {sup 70}Ge and {sup 209}Bi in or close to the respective Gamow window were collected and can be compared to theoretical predictions. The aim of both databases is a quick and user-friendly access to the available data in the astrophysically relevant energy regions.

  17. Low Temperature Synthesis of Cubic-phase Fast-ionic Conducting Bi-doped Garnet Solid State Electrolytes

    NASA Astrophysics Data System (ADS)

    Schwanz, Derek K.; Marinero, Ernesto

    We report on the synthesis of cubic-phase fast ionic conducting garnet solid state electrolytes based on LiLaZrO (LLZO) at unprecedented low synthesis temperatures. Ionic conductivities around 1.2 x 10-4 S/cm are readily achieved. Bismuth aliovalent substitution into LLZO utilizing the Pechini processing method is successfully employed to synthesize LiLaZrBiO compounds. Cubic phase LiLaZrBiO powders are generated in the temperature range 650C to 900C in air. In contrast, in the absence of Bi and under identical synthesis conditions, the cubic phase of LiLaZrO is not formed below 750C and a transformation to the poor ionically conducting tetragonal phase is observed at 800C for the undoped compound. The critical role of Bi in lowering the formation temperature of the garnet cubic phase and the improvements in ionic conductivity are elucidated in this work through microstructural and electrochemical studies.

  18. Configuration dependence of band-gap narrowing and localization in dilute GaAs1 -xBix alloys

    NASA Astrophysics Data System (ADS)

    Bannow, Lars C.; Rubel, Oleg; Badescu, Stefan C.; Rosenow, Phil; Hader, Jörg; Moloney, Jerome V.; Tonner, Ralf; Koch, Stephan W.

    2016-05-01

    Anion substitution with bismuth (Bi) in III-V semiconductors is an effective method for experimental engineering of the band gap Eg at low Bi concentrations (≤2 % ), in particular in gallium arsenide (GaAs). The inverse Bi-concentration dependence of Eg has been found to be linear at low concentrations x and dominated by a valence band defect level anticrossing between As and Bi occupied p levels. Predictive models for the valence band hybridization require a first-principle understanding which can be obtained by density functional theory with the main challenges being the proper description of Eg and the spin-orbit coupling. By using an efficient method to include these effects, it is shown here that at high concentrations Eg is modified mainly by a Bi-Bi p orbital interaction and by the large Bi atom-induced strain. In particular, we find that at high concentrations, the Bi-Bi interactions depend strongly on model periodic cluster configurations, which are not captured by tight-binding models. Averaging over various configurations supports the defect level broadening picture. This points to the role of different atomic configurations obtained by varying the experimental growth conditions in engineering arsenide band gaps, in particular for telecommunication laser technology.

  19. Incoherent Bi off-centering in Bi₂Ti₂O₆O' and Bi₂Ru₂O₆O': Insulator versus metal

    DOE PAGESBeta

    Shoemaker, Daniel P.; Seshadri, Ram; Tachibana, Makoto; Hector, Andrew L.

    2011-08-24

    In the cubic, stoichiometric oxide compounds Bi₂Ti₂O₆O' (also written as Bi₂Ti₂O₇) and Bi₂Ru₂O₆O' (also written as Bi₂Ru₂O₇) Bi³⁺ ions on the pyrochlore A site display a propensity to off-center. Unlike Bi₂Ti₂O₆O', Bi₂Ru₂O₆O' is a metal, so it is of interest to ask whether conduction electrons and/or involvement of Bi 6s states at the Fermi energy influence Bi³⁺ displacements. The Bi³⁺ off-centering in Bi₂Ti₂O₆O' has previously been revealed to be incoherent from detailed reverse Monte Carlo analysis of total neutron scattering. Similar analysis of Bi₂Ru₂O₆O' reveals incoherent off-centering as well, but of smaller magnitude and with distinctly different orientational preference. Analysismore » of the distributions of metal to oxygen distances presented suggests that Bi in both compounds is entirely Bi³⁺. Disorder in Bi₂Ti₂O₆O' has the effect of stabilizing valence while simultaneously satisfying the steric constraint imposed by the presence of the lone pair of electrons. In Bi₂Ru₂O₆O', off-centering is not required to satisfy valence and seems to be driven by the lone pair. Decreased volume of the lone pair may be a result of partial screening by conduction electrons.« less

  20. Incoherent Bi off-centering in Bi₂Ti₂O₆O' and Bi₂Ru₂O₆O': Insulator versus metal

    SciTech Connect

    Shoemaker, Daniel P.; Seshadri, Ram; Tachibana, Makoto; Hector, Andrew L.

    2011-08-24

    In the cubic, stoichiometric oxide compounds Bi₂Ti₂O₆O' (also written as Bi₂Ti₂O₇) and Bi₂Ru₂O₆O' (also written as Bi₂Ru₂O₇) Bi³⁺ ions on the pyrochlore A site display a propensity to off-center. Unlike Bi₂Ti₂O₆O', Bi₂Ru₂O₆O' is a metal, so it is of interest to ask whether conduction electrons and/or involvement of Bi 6s states at the Fermi energy influence Bi³⁺ displacements. The Bi³⁺ off-centering in Bi₂Ti₂O₆O' has previously been revealed to be incoherent from detailed reverse Monte Carlo analysis of total neutron scattering. Similar analysis of Bi₂Ru₂O₆O' reveals incoherent off-centering as well, but of smaller magnitude and with distinctly different orientational preference. Analysis of the distributions of metal to oxygen distances presented suggests that Bi in both compounds is entirely Bi³⁺. Disorder in Bi₂Ti₂O₆O' has the effect of stabilizing valence while simultaneously satisfying the steric constraint imposed by the presence of the lone pair of electrons. In Bi₂Ru₂O₆O', off-centering is not required to satisfy valence and seems to be driven by the lone pair. Decreased volume of the lone pair may be a result of partial screening by conduction electrons.

  1. Rain-Induced Increase in Background Radiation Detected by Radiation Portal Monitors

    SciTech Connect

    Hausladen, Paul; Blessinger, Christopher S; Guzzardo, Tyler; Livesay, Jake

    2012-07-01

    A complete understanding of both the steady state and transient background measured by Radiation Portal Monitors (RPMs) is essential to predictable system performance, as well as maximization of detection sensitivity. To facilitate this understanding, a test bed for the study of natural background in RPMs has been established at the Oak Ridge National Laboratory. This work was performed in support of the Second Line of Defense Program's mission to detect the illicit movement of nuclear material. In the present work, transient increases in gamma ray counting rates in RPMs due to rain are investigated. The increase in background activity associated with rain, which has been well documented in the field of environmental radioactivity, originates from the atmospheric deposition of two radioactive daughters of radon-222, namely lead-214 and bismuth-214 (henceforth {sup 222}Rn, {sup 214}Pb and {sup 214}Bi). In this study, rainfall rates recorded by a co-located weather station are compared with RPM count rates and High Purity Germanium spectra. The data verifies these radionuclides are responsible for the dominant transient natural background fluctuations in RPMs. Effects on system performance and potential mitigation strategies are discussed.

  2. Determination of bismuth in environmental samples by slurry sampling graphite furnace atomic absorption spectrometry using combined chemical modifiers.

    PubMed

    Dobrowolski, Ryszard; Dobrzyńska, Joanna; Gawrońska, Barbara

    2015-01-01

    Slurry sampling graphite furnace atomic absorption spectrometry technique was applied for the determination of Bi in environmental samples. The study focused on the effect of Zr, Ti, Nb and W carbides, as permanent modifiers, on the Bi signal. Because of its highest thermal and chemical stability and ability to substantially increase Bi signal, NbC was chosen as the most effective modifier. The temperature programme applied for Bi determination was optimized based on the pyrolysis and atomization curves obtained for slurries prepared from certified reference materials (CRMs) of the soil and sediments. To overcome interferences caused by sulfur compounds, Ba(NO₃)₂ was used as a chemical modifier. Calibration was performed using the aqueous standard solutions. The analysis of the CRMs confirmed the reliability of the proposed analytical method. The characteristic mass for Bi was determined to be 16 pg with the detection limit of 50 ng/g for the optimized procedure at the 5% (w/v) slurry concentration. PMID:25384374

  3. Biosimilar Insulins

    PubMed Central

    Hompesch, Marcus

    2014-01-01

    Until now most of the insulin used in developed countries has been manufactured and distributed by a small number of multinational companies. Beyond the established insulin manufacturers, a number of new players have developed insulin manufacturing capacities based on modern biotechnological methods. Because the patents for many of the approved insulin formulations have expired or are going to expire soon, these not yet established companies are increasingly interested in seeking market approval for their insulin products as biosimilar insulins (BI) in highly regulated markets like the EU and the United States. Differences in the manufacturing process (none of the insulin manufacturing procedures are 100% identical) can lead to insulins that to some extent may differ from the originator insulin. The key questions are if subtle differences in the structure of the insulins, purity, and so on are clinically relevant and may result in different biological effects. The aim of this article is to introduce and discuss basic aspects that may be of relevance with regard to BI. PMID:24876530

  4. Design and Experimental Investigation of a Compact Circularly Polarized Integrated Filtering Antenna for Wearable Biotelemetric Devices.

    PubMed

    Jiang, Zhi Hao; Gregory, Micah D; Werner, Douglas H

    2016-04-01

    A compact circularly polarized (CP) integrated filtering antenna is reported for wearable biotelemetric devices in the 2.4 GHz ISM band. The design is based on a mutual synthesis of a CP patch antenna connected to a bandpass filter composed of coupled stripline open-loop resonators, which provides an integrated low-profile radiating and filtering module with a compact form factor of 0.44λ(0)×0.44λ(0)×0.04λ(0). The optimized filtering antenna is fabricated and measured, achieving an S11 < -14 dB, an axial ratio of less than 3 dB and gain higher than 3.5 dBi in the targeted ISM band. With the integrated filtering functionality, the antenna exhibits good out-of-band rejection over an ultra-wide frequency range of 1-6 GHz. Further full-wave simulations and experiments were carried out, verifying that the proposed filtering antenna maintains these desirable properties even when mounted in close proximity to the human body at different positions. The stable impedance performance and the simultaneous wide axial ratio and radiated power beam widths make it an ideal candidate as a wearable antenna for off-body communications. The additional integrated filtering functionality further improves utility by greatly reducing interference and crosstalk with other existing wireless systems. PMID:26186795

  5. Theoretical investigation of charge accumulation layer on the Bi-induced InAs(111)-(2 × 2) surface

    SciTech Connect

    Özkaya, S.; Usanmaz, D.; Çakmak, M.; Alkan, B.; Ellialtıoğlu, Ş.

    2014-04-28

    Based on pseudopotential method and density functional theory, we have investigated the stability, atomic geometry, and detailed electronic structures for Bi adsorbates on the InAs(111)-(2 × 2) surface with three different sites: (i) T{sub 4} (Bi trimer centered on T{sub 4} site), (ii) H{sub 3} (Bi trimer centered on H{sub 3} site), and (iii) T{sub 4}–H{sub 3} (which is formed by trimers with opposite orientations: one centered on a T{sub 4} site and the other on a H{sub 3}). Our total energy calculations suggest that adsorption on the T{sub 4}–H{sub 3} site is the energetically most stable structure among the proposed structures. The electronic band structure calculations reveal the existence of an accumulation layer between InAs(111) surface and Bi adatoms for T{sub 4}–H{sub 3}. Charge density difference results indicate significant amount of the charge accumulation on the Bi/InAs interface.

  6. Potential-step chronocoulometric investigation of the surface coverages of coadsorbed Bi and hydroxide on Au(111) electrodes

    SciTech Connect

    Niece, B.K.; Gewirth, A.A.

    1996-10-02

    Bi underpotentially deposited on Au(111) has been studied using potential-step chronocoulometry to determine the actual surface coverage of Bi. In the potential region where this system exhibits catalytic activity for the electroreduction of peroxide to water, the observed coverage is 0.25 monolayer (ML), which agrees well with the coverage of the reported (2 x 2) Bi overlayer observed by scanning probe microscopy in this region. At more cathodic potentials, the coverage increases to 0.67 ML. This coverage agrees with the expected based on the (p x {radical}3) structure proposed from scanning tunneling microscopy, atomic force microscopy, and SXS measurements in this region. The electrosorption valency calculated based on these coverages is 3, indicating that the Bi is fully discharged on the surface. Potential-step chronocoulometry has been used at various pH values to determine the surface coverage of hydroxide anion in the presence of underpotentially deposited (upd) Bi. The coverage is negligible in the absence of upd Bi and at potentials where the Bi adlayer condenses. It rises to a peak of 0.17 ML in the region where the coverage is 0.25 ML, indicating that OH{sup -} is coadsorbed with the Bi. 30 refs., 10 figs.

  7. Robust surface state transport in thin bismuth nanoribbons

    PubMed Central

    Ning, Wei; Kong, Fengyu; Han, Yuyan; Du, Haifeng; Yang, Jiyong; Tian, Mingliang; Zhang, Yuheng

    2014-01-01

    While a two-dimensional (2D) metallic surface state in bismuth has been proposed, experimental 2D evidence of quantum transport, e.g., angular dependent Shubnikov-de Haas (SdH) oscillations is still lacking. Here, we report the angular-dependent magnetoresistance measurements in single-crystal Bi nanoribbons, and found that both the low-field weak antilocalization behavior and the high-field angle-dependent SdH oscillations follow exactly the 2D character, indicative of the 2D metallic surface states which dominate the transport properties of thin Bi nanoribbons. Moreover, by controllable exposing the ribbons to ambient environment (1 atm and room temperature), the metallic surface states were found to be robust to the oxidation although the carrier density in the surface states are modified after the exposures. These results suggest that the metallic surface states in Bi nanoribbons should be topologically protected which can provide key information in understanding the surface properties of Bi in nanometer scale. PMID:25404036

  8. SR-BI protects against endotoxemia in mice through its roles in glucocorticoid production and hepatic clearance

    PubMed Central

    Cai, Lei; Ji, Ailing; de Beer, Frederick C.; Tannock, Lisa R.; van der Westhuyzen, Deneys R.

    2007-01-01

    Septic shock results from an uncontrolled inflammatory response, mediated primarily by LPS. Cholesterol transport plays an important role in the host response to LPS, as LPS is neutralized by lipoproteins and adrenal cholesterol uptake is required for antiinflammatory glucocorticoid synthesis. In this study, we show that scavenger receptor B-I (SR-BI), an HDL receptor that mediates HDL cholesterol ester uptake into cells, is required for the normal antiinflammatory response to LPS-induced endotoxic shock. Despite elevated plasma HDL levels, SR-BI–null mice displayed an uncontrollable inflammatory cytokine response and a markedly higher lethality rate than control mice in response to LPS. In addition, SR-BI–null mice showed a lack of inducible glucocorticoid synthesis in response to LPS, bacterial infection, stress, or ACTH. Glucocorticoid insufficiency in SR-BI–null mice was due to primary adrenal malfunction resulting from deficient cholesterol delivery from HDL. Furthermore, corticosterone supplementation decreased the sensitivity of SR-BI–null mice to LPS. Plasma from control and SR-BI–null mice exhibited a similar ability to neutralize LPS, whereas SR-BI–null mice showed decreased plasma clearance of LPS into the liver and hepatocytes compared with normal mice. We conclude that SR-BI in mice is required for the antiinflammatory response to LPS-induced endotoxic shock, likely through its essential role in facilitating glucocorticoid production and LPS hepatic clearance. PMID:18064300

  9. {alpha} decay of {sup 216}Fr and {sup 212}At

    SciTech Connect

    Liang, C.F.; Paris, P.; Sheline, R.K.; Alexa, P.; Gizon, A.

    1996-11-01

    The alpha and coincident gamma decays of {sup 216}Fr and {sup 212}At in secular equilibrium with 0.8 s {sup 224}Pa and 26.1 ms {sup 220}Ac have been studied with emphasis on the level scheme of {sup 212}At. The level structure has been interpreted in terms of the shell model configurations {pi}({ital h}{sub 9/2}){sub 9/2}{sup 3}{nu}({ital g}{sub 9/2}), {pi}({ital h}{sub 9/2}){sub 0+}{sup 2}({ital f}{sub 7/2}){nu}({ital g}{sub 9/2}), and {pi}({ital h}{sub 9/2}){sub 9/2}{sup 3}{nu}({ital i}{sub 11/2}). These configurations are then compared with the calculated configurations in {sup 212}At and with the corresponding experimental configurations in {sup 210}Bi and {sup 212}Bi. In all three cases plots of the experimental energies vs the spin show the expected inverted parabola shape, but as we move farther away from the {sup 208}Pb closed shells, the inverted parabolas become more compressed. {copyright} {ital 1996 The American Physical Society.}

  10. InAsSbBi, a direct band-gap, III-V, LWIR material

    NASA Technical Reports Server (NTRS)

    Stringfellow, G. B.; Jones, Colin E.; Frodsham, John

    1990-01-01

    In the last several years Dr. Stringfellow's group at the University of Utah has reported success in incorporating over 3 percent Bi in InAs and 1.5 percent in InAsSb using Organometallic Vapor Phase Epitaxy (OMVPE) growth techniques. For InAs the lattice constant increase is linear with a=6.058+0.966x (InAs(1-x)Bi(x)), and a decrease in band gap energy of dEg / dx = -55meV / at a percentage Bi. Extrapolating this to the ternary minimum band gap at InAs(0.35)Sb(0.65), an addition of 1 to 2 percent Bi should drop the band gap to the 0.1 to 0.05eV range (10 to 20 microns). These alloys are direct band gap semiconductors making them candidates for far IR detectors. The current status of the InAsSbBi alloys is that good crystal morphology and x ray diffraction data has been obtained for up to 3.4 percent Bi. The Bi is metastable at these concentrations but the OMVPE grown material has been able to withstand the 400 C growth temperature for several hours without phase separation.

  11. Extending the Reach of Early Intervention Training for Practitioners: A Preliminary Investigation of an Online Curriculum for Teaching Behavioral Intervention Knowledge in Autism to Families and Service Providers

    PubMed Central

    Hamad, Charles D.; Serna, Richard W.; Morrison, Leslie; Fleming, Richard

    2013-01-01

    Early behavioral intervention, based on the methods of applied behavior analysis, has the strongest and most consistent scientific support as a means of teaching skills to young children with Autism Spectrum Disorder and reducing their restricted and maladaptive behavior. Though individual ABA-based treatment plans are usually developed, designed and supervised by a senior-level clinician, they are most often implemented by a practitioner, such as a parent, direct service provider, aide, or an early childhood professional from a related discipline. Unfortunately, few practitioner-orientated training programs are available to geographically disparate persons. Online distance-learning education offers a potential solution to this problem. Fifty-one individuals participated in an initial study of a short, three-module online course. The results showed a highly statistically significant difference between the mean pre-test and post-test score. The outcomes suggest the feasibility and user satisfaction of teaching BI knowledge acquisition online, and thus bolster confidence that future, larger-scale curricula aimed at teaching BI in a distance-learning format is warranted. PMID:23504540

  12. LnPO4 nanoparticles doped with Ac-225 and sequestered daughters for targeted alpha therapy.

    PubMed

    McLaughlin, Mark F; Robertson, David; Pevsner, Paul H; Wall, Jonathan S; Mirzadeh, Saed; Kennel, Stephen J

    2014-02-01

    For targeted alpha therapy (TAT) with 225Ac, daughter radioisotopes from the parent emissions should be controlled. Here, we report on a second-generation layered nanoparticle (NP) with improved daughter retention that can mediate TAT of lung tumor colonies. NPs of La3+, Gd3+, and 225Ac3+ ions were coated with additional layers of GdPO4 and then coated with gold via citrate reduction of NaAuCl4. MAb 201b, targeting thrombomodulin in lung endothelium, was added to a polyethylene glycol (dPEG)-COOH linker. The NPs:mAb ratio was quantified by labeling the mAb with 125I. NPs showed 30% injected dose/organ antibody-mediated uptake in the lung, which increased to 47% in mice pretreated with clodronate liposomes to reduce phagocytosis. Retention of daughter 213Bi in lung tissue was more than 70% at one hour and about 90% at 24 hours postinjection. Treatment of mice with lung-targeted 225Ac NP reduced EMT-6 lung colonies relative to cold antibody competition for targeting or phosphate-buffered saline injected controls. We conclude that LnPO4 NPs represent a viable solution to deliver the 225Ac as an in vivo α generator. The NPs successfully retain a large percentage of the daughter products without compromising the tumoricidal properties of the α-radiation. PMID:24102173

  13. Racial differences in sensitivity to behavioral integrity: attitudinal consequences, in-group effects, and "trickle down" among Black and non-Black employees.

    PubMed

    Simons, Tony; Friedman, Ray; Liu, Leigh Anne; McLean Parks, Judi

    2007-05-01

    Recent research has suggested that employees are highly affected by perceptions of their managers' pattern of word-action consistency, which T. Simons (2002) called behavioral integrity (BI). The authors of the present study suggest that some employee racial groups may be more attentive to BI than others. They tested this notion using data from 1,944 employees working at 107 different hotels and found that Black employees rated their managers as demonstrating lower BI than did non-Black employees. Mediation analyses were consistent with the notion that these differences in perceived BI in turn account for cross-race differences in trust in management, interpersonal justice, commitment, satisfaction, and intent to stay. Results of hierarchical linear modeling were consistent with the idea that middle managers' perceptions of their senior managers' BI "trickle down" to affect line employee perceptions of the middle managers and that this trickle-down effect is stronger for Black employees. The authors interpret these results as indicative of heightened sensitivity to managers' BI on the part of Black employees. They also found a reverse in-group effect, in that Black employees were substantially more critical of Black managers than were non-Black employees. PMID:17484548

  14. O the Existence of bi 6.67O 4( xo 4) 4 and PbBi 6O 4( xo 4) 4 ( X=P, V, and As)

    NASA Astrophysics Data System (ADS)

    Giraud, Sophie; Drache, Michel; Conflant, Pierre; Wignacourt, Jean Pierre; Steinfink, Hugo

    2000-11-01

    PbBi6O4(PO4)4 obtained at room temperature is isomorphous with the high-temperature phase Bi6.67O4(PO4)4. The Pb atom replaces 0.67 Bi in the same crystallographic site. The vanadate and arsenate with the composition PbBi6O4(XO4)4 were synthesized and yielded isomorphic phases at room temperature. All three compounds adopt a triclinic cell, space group Poverline1Z=1. The structure refinement of PbBi6O4(PO4)4 was performed using the Rietveld method on X-ray powder diffraction data. The starting parameters were the atomic positions of Bi6.67O4(PO4)4. Conductivity measurements were made from 300°C to 800°C on samples of the three homologues. The highest conductivity was observed for the vanadate. Attempts to synthesize the binary vanadate and arsenate compounds isostructural with the high-temperature phase Bi6.67O4(PO4)4 were unsuccessful.

  15. [Determination of 27 elements in Maca nationality's medicine by microwave digestion ICP-MS].

    PubMed

    Yu, Gui-fang; Zhong, Hai-jie; Hu, Jun-hua; Wang, Jing; Huang, Wen-zhe; Wang, Zhen-zhong; Xiao, Wei

    2015-12-01

    An analysis method has been established to test 27 elements (Li, Be, B, Mg, Al, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Sr, Mo, Cd, Sn, Sb, Ba, La, Hg, Pb, Bi) in Maca nationality's medicine with microwave digestion-ICP-MS. Sample solutions were analyzed by ICP-MS after microwave digestion, and the contents of elements were calculated according to their calibration curves, and internal standard method was adopted to reduce matrix effect and other interference effects. The experimental results showed that the linear relations of all the elements were very good; the correlation coefficient (r) was 0.9994-1.0000 (Hg was 0.9982) ; the limits of detection were 0.003-2.662 microg x L(-1); the relative standard deviations for all elements of reproducibility were lower than 5% (except the individual elements); the recovery rate were 78.5%-123.7% with RSD lower than 5% ( except the individual elements). The analytical results of standard material showed acceptable agreement with the certified values. This method was applicable to determinate the contents of multi-elements in Maca which had a high sensitivity, good specificity and good repeatability, and provide basis for the quality control of Maca. PMID:27141662

  16. Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering

    NASA Astrophysics Data System (ADS)

    Çınar, Simge; Tevis, Ian D.; Chen, Jiahao; Thuo, Martin

    2016-02-01

    Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate (‘/’ = physisorbed, ‘-’ = chemisorbed), from molten Field’s metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity.

  17. Dependence of the lone pair of bismuth on coordination environment and pressure: An ab initio study on Cu{sub 4}Bi{sub 5}S{sub 10} and Bi{sub 2}S{sub 3}

    SciTech Connect

    Arnskov Olsen, Lars; Lopez-Solano, Javier; Garcia, Alberto; Balic-Zunic, Tonci; Makovicky, Emil

    2010-09-15

    DFT calculations have been carried out for Cu{sub 4}Bi{sub 5}S{sub 10} and Bi{sub 2}S{sub 3} to provide an analysis of the relation between electronic structure, lone electron pairs and the local geometry. The effect of pressure is considered in Bi{sub 2}S{sub 3} and the results are compared to published experimental data. Bi{sup 3+} in Cu{sub 4}Bi{sub 5}S{sub 10} is found at both symmetrically and asymmetrically coordinated sites, whereas the coordination environments of Bi in Bi{sub 2}S{sub 3} are asymmetric at room conditions and get more regular with increasing pressure. The charge density maps of the asymmetric sites show the lone pairs as lobes of non-shared charge. These lobes are related to an effective Bi s-Bi p hybridization resulting from coupling to S p orbitals, supporting the modern view of the origin of the stereochemically active lone pair. No effective Bi s-p hybridization is seen for the symmetric site in Cu{sub 4}Bi{sub 5}S{sub 10}, whereas Bi s-p hybridization coexists with a much reduced lone pair in Bi{sub 2}S{sub 3} at high pressure. - Graphical abstract: The article includes charge density maps used to analyze the charge distribution around bismuth in sulfides. This map shows the orientation of a lone electron pair.

  18. Structural and electronic properties of half-Heusler alloys PtXBi (with X=Mn, Fe, Co and Ni) calculated from first principles

    NASA Astrophysics Data System (ADS)

    Huang, Wenchao; Wang, Xiaofang; Chen, Xiaoshuang; Lu, Wei; Damewood, L.; Fong, C. Y.

    2015-03-01

    First principles calculations with spin polarization based on density functional theory have been performed on half-Heusler alloys PtXBi, with X=Mn, Fe, Co and Ni, in three different atomic configurations (i.e. α, β, and γ phases). For each configuration, their optimized lattice constants are determined. Electronic and magnetic properties are also investigated. The differences reflect the atomic arrangements of the three phases and varied transition metal elements X. Meanwhile, the possibility of having the integer magnetic moment for each phase is explored. PtMnBi in α phase show half-metallic (HM) properties when its lattice constant is reduced from -3.0% to -11.2% with magnetic moment consistent with the values given by the modified Slater-Pauling rule. Additionally, we examined the effects of the spin-orbit (S-O) interaction on half-metal PtMnBi by comparing the relative shifts of the valence bands and the indirect semiconducting gap with respect to the spin polarized results.

  19. Influence of electron-ion collisions on Buneman instability

    NASA Astrophysics Data System (ADS)

    Rostomyan, Eduard

    2016-07-01

    Buneman instability (BI) [1] has been found to play a role in many scenarios in space physics and geophysics. It has also been invoked to explain many phenomena in the earth ionosphere [2] and in the solar chromosphere [3]. In double-layer and collisionless shock physics the same instability has been found responsible in formation of nonlinear structures [4]. In situations where an electron beam enters plasma, like in the fast ignition scenario for inertial fusion [5], Buneman modes are excited and play essential role [6]. BI is caused by motion of plasma electrons against ions. However, up to now investigations on BI did not take into account influence collisions in plasma (for quantum case a paper has recently appeared [7]). Influence of collisions may be very important especially in dense fully ionized plasma with long distance character of interaction. Particularly collisions lead to energy dissipation with an array of ensuing effects e.g. change of the instability physical nature to that of dissipative type [8]. Due to role of BI in various processes in space (and laboratory) plasma necessity of the consideration is long overdue. Absence of investigations on a problem along with its importance may be explained by its complexity only. For given case correct consideration should be based on solution of transport equation with collisional term. In fully ionized plasma correct description of collisions is given by Landau collision integral (LCI) [9]. This is very complex formation. It greatly complicates transport equation and actually makes it intractable. Since its formulation in 1936, there is very little literature on solution of the transport equation with LCI. Almost all successful attempts to accommodate influence of collisions on various processes in plasma are based on BGK model [10]. This model is much simpler. However in fully ionized plasma usage LCI is more appropriate as it is designed for system with long distance character of particle interaction

  20. M-shell x-ray production cross section measurements in Pb and Bi due to the impact of protons and nickel ions

    NASA Astrophysics Data System (ADS)

    Braich, Jasbir S.; Verma, Punita; Verma, H. R.

    1997-05-01

    M-shell x-ray production cross sections in Pb have been measured using 58 - 82 MeV 0953-4075/30/10/011/img1 ions and those in Bi by 1 - 5 MeV protons and 58 - 82 MeV 0953-4075/30/10/011/img2 ions (q = 5, 6). The experimental results have been compared with the predictions of the plane-wave Born approximation (PWBA) and with the calculations of the perturbed stationary state theory (ECPSSR) accounting for the energy loss (E), Coulomb deflection (C) and relativistic (R) effects. The present results of proton impact on bismuth have also been compared with the experimental data available from other investigations. To the best of our knowledge, the M-shell x-ray production cross sections in Pb and Bi by Ni-ion impact are reported here for the first time. Good agreement of the present results with the predictions of the ECPSSR theory has been observed for the total M x-ray cross sections in Bi due to proton impact while discrepancies to a factor of 1.5 - 2.5 in the case of total M x-ray cross sections have been observed between the present experimental and theoretical (PWBA and ECPSSR, respectively) results for Pb and Bi in the case of Ni-ion impact. These discrepancies between the experimental and theoretical results could be attributed to the effect of multiple ionization on the x-ray emission probabilities. If the modified value of the average fluorescence yield accounting for the outer-shell multiple ionization is used, the theoretical results of total M-shell x-ray cross sections based on the PWBA theory show fair agreement with the experimental results (within experimental uncertainties) while the ECPSSR theory is found to underestimate the experimental results by about 40% for both Pb and Bi in the case of Ni-ion impact. Furthermore, the 0953-4075/30/10/011/img3 and 0953-4075/30/10/011/img4 x-ray cross sections have been evaluated experimentally for both Pb and Bi. The comparison of these results with the corresponding theoretical estimates have been done only for

  1. Gold enrichment and the Bi-Au association in pyrrhotite-rich massive sulfide deposits, Escanaba trough, Southern Gorda Ridge

    USGS Publications Warehouse

    Tormanen, T.O.; Koski, R.A.

    2005-01-01

    High gold contents (to 10.1 ppm, avg 1.4 ppm, n = 34) occur in pyrrhotite-rich massive sulfide samples from the sediment-covered floor of the Escanaba trough, the slow-spreading, southernmost segment of Gorda Ridge. These concentrations reflect the presence of primary gold, formed during high-temperature hydrothermal activity in mounds and chimneys, and secondary gold deposited during sea-floor weathering of massive sulfide. Primary gold occurs as fine-grained (2 ??m) secondary gold grains have a porous, flaky morphology and occur in samples in which pyrrhotite is oxidized and replaced by Fe oxyhydroxides, Fe sulfate, and sulfur. Mounds and chimneys dominated by pyrrhotite and containing lesser amounts of isocubanite, chalcopyrite, and Fe-rich sphalerite were formed by high-temperature (estimated range 325??-275??C), reduced, low-sulfur vent fluids. The mineral and fluid compositions during this main stage of hydrothermal venting reflect subsurface interaction between circulating hydrothermal fluids and turbiditic sediment containing as much as 1.1 percent organic carbon. As the deposition of pyrrhotite, Cu-Fe sulfides, and sphalerite waned, a volumetrically minor suite of sulfarsenide, arsenide, Bi, and Au minerals was deposited from highly reduced, late main-stage fluids diffusing through mounds and chimneys. The low solubility of Au as a bisulfide complex and the absence of fluid mixing during this stage of hydrothermal activity apparently inhibited the precipitation of gold directly from solution. Instead, gold precipitation is thought to be linked to elevated concentrations of Bi in the late main-stage fluids. The textural relationships of Au and Bi minerals in pyrrhotite-rich samples, low melting point of native bismuth (271.4??C), and recent experimental results on Au and Bi in hydrothermal fluids contribute to the hypothesis that gold was effectively scavenged from the Escanaba trough vent fluids by coexisting droplets of liquid bismuth. Additional phase

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  3. Slowly fading super-luminous supernovae that are not pair-instability explosions.

    PubMed

    Nicholl, M; Smartt, S J; Jerkstrand, A; Inserra, C; McCrum, M; Kotak, R; Fraser, M; Wright, D; Chen, T-W; Smith, K; Young, D R; Sim, S A; Valenti, S; Howell, D A; Bresolin, F; Kudritzki, R P; Tonry, J L; Huber, M E; Rest, A; Pastorello, A; Tomasella, L; Cappellaro, E; Benetti, S; Mattila, S; Kankare, E; Kangas, T; Leloudas, G; Sollerman, J; Taddia, F; Berger, E; Chornock, R; Narayan, G; Stubbs, C W; Foley, R J; Lunnan, R; Soderberg, A; Sanders, N; Milisavljevic, D; Margutti, R; Kirshner, R P; Elias-Rosa, N; Morales-Garoffolo, A; Taubenberger, S; Botticella, M T; Gezari, S; Urata, Y; Rodney, S; Riess, A G; Scolnic, D; Wood-Vasey, W M; Burgett, W S; Chambers, K; Flewelling, H A; Magnier, E A; Kaiser, N; Metcalfe, N; Morgan, J; Price, P A; Sweeney, W; Waters, C

    2013-10-17

    Super-luminous supernovae that radiate more than 10(44) ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of (56)Ni are synthesized; this isotope decays to (56)Fe via (56)Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10(-6) times that of the core-collapse rate. PMID:24132291

  4. Radionuclide concentrations in fish and invertebrates from Bikini Atoll

    SciTech Connect

    Noshkin, V.E.; Wong, K.M.; Eagle, R.J.; Jokela, T.A.; Brunk, J.A.

    1988-01-01

    As in other global studies, /sub 137/Cs was found in the highest concentrations in edible flesh of all species of fish and in the lowest concentrations in the bone or liver. The mean concentration of /sup 137/Cs in muscle of reef fish from the southern part of the atoll is comparable to the global-fallout concentration measured in market samples of fish collected from Chicago, IL, USA, in 1982. Strontium-90 is associated generally with non-edible parts of fish, such as bone or viscera. Twenty-five to fifty percent of the total body burden of /sub 60/Co is accumulated in the muscle tissue; the remainder is distributed among the liver, skin, and viscera. The mean concentration of /sub 60/Co in fish has been decreasing at a rate faster than radiological decay alone. Most striking is the range of /sup 207/Bi concentrations among different species of fish collected at the same time and place. Highest concentrations of /sup 207/Bi were consistently detected in the muscle and other tissues of goatfish and some of the pelagic lagoon fish. In other reef fish, such as mullet, surgeonfish, and parrotfish, /sub 207/Bi was usually below detection limits by gamma spectrometry. Over 70% of the whole-body activity of /sup 207/Bi in goatfish is associated with the muscle tissue, whereas less than 5% is found in the muscle of mullet and surgeonfish. Neither /sup 239 +240/Pu nor /sup 241/Am is accumulated significantly in the muscle tissue of any species of fish. Apparently, /sup 238/Pu is in a more readily available form for accumulation by fishes than /sup 239 +240/Pu. Based on a daily ingestion rate of 200 g of fish flesh, dose rates to individuals through the fish-food ingestion pathway are well below current Federal guidelines. 24 refs., 1 fig., 27 tabs

  5. Comparison of provider-documented and patient-reported brief intervention for unhealthy alcohol use in VA outpatients☆

    PubMed Central

    Lapham, Gwen T.; Rubinsky, Anna D.; Shortreed, Susan M.; Hawkins, Eric J.; Richards, Julie; Williams, Emily C.; Berger, Douglas; Chavez, Laura J.; Kivlahan, Daniel R.; Bradley, Katharine A.

    2015-01-01

    Background Performance measures for brief alcohol interventions (BIs) are currently based on provider documentation of BI. However, provider documentation may not be a reliable measure of whether or not patients are offered clinically meaningful BIs. In particular, BI documented with clinical decision support in an electronic medical record (EMR) could appear identical irrespective of the quality of BI provided. We hypothesized that differences in how BI was implemented across health systems could lead to differences in the proportion of documented BI recalled and reported by patients across health systems. Methods Male outpatients with unhealthy alcohol use identified by confidential satisfaction surveys (2009–2012) were assessed for whether they reported receiving BI in the past year (patient-reported BI) and whether they had BI documented in the EMR during the same period (documented BI). We evaluated and compared the prevalence of documented BI to patient-reported BI across 21 VA networks to determine whether documented BI had a variable association with patient-reported BI across the networks. Results Of 9896 eligible male outpatients with unhealthy alcohol use, 59.0% (95% CI 57.4–60.5%) reported BI (50.4–64.9% across networks) and 37.4% (95% CI 36.0–38.9%) had BI documented in the EMR (28.0–44.2% across networks). Overall, 72.9% (95% CI 70.8–75.5%) of patients with documented BI also reported BI. The association between documented BI and patient-reported BI did not vary across VA networks in adjusted logistic regression models. Conclusions Performance measures of BI that rely on provider documentation in EMRs appear comparable to patient report for comparing care across VA networks. PMID:26072218

  6. Nuclear Data Sheets for A = 199

    NASA Astrophysics Data System (ADS)

    Singh, Balraj

    2007-01-01

    Nuclear spectroscopic information for known nuclides of mass number 199 (Os,Ir,Pt,Au,Hg,Tl,Pb,Bi,Po,At,Rn,Fr) with Z = 76 to 87 and N = 123 to 112 have been evaluated and presented together with adopted energies and Jπ of levels in these nuclei. No excited state data are available for 199Os and 199Fr, and very little information is available for levels in 199Ir, 199Rn and 199At. The decay of 199Ir to 199Pt has not been studied. The decay of the 90-min activity of 199Pb to 199Tl is known in detail but remains unpublished in the open literature, while the decay of the 12.2-min isomer remains mostly unknown. The decays of the two activities of 199Tl to 199Pb are not known as separate decay scheme for each of the activities, thus only a composite decay scheme is presented. Similar is the case for the decay of the two activities of 199Po to 199Bi. In ( 3He,d) and (α,t) studies for 199Au, disagreements are found between two independent contemporary studies. The most detailed structure known is for 199Pb with five magnetic-rotational (MR) dipole bands together with many other dipole bands which are of probable multi-quasiparticle nature. This work supersedes previous evaluations of A = 199 published in update mode by 1994Ar13; as full A-chain updates by 1988Sc02, 1978Ha12 and 1971Le37; and a mid-stream update of 199Pb nuclide by 2001Si44.

  7. Immunoglobulin G Fc N-glycan profiling in patients with gastric cancer by LC-ESI-MS: relation to tumor progression and survival.

    PubMed

    Kodar, Kristel; Stadlmann, Johannes; Klaamas, Kersti; Sergeyev, Boris; Kurtenkov, Oleg

    2012-01-01

    The IgG Fc glycans strongly influence the Fcγ receptor interactions and Fc-mediated effector mechanisms. Changes in the structure of IgG glycans are associated with various diseases, such as infections and autoimmunity. However, the possible role of Fc glycans in tumor immunity is not yet fully understood. The aim of this study was to profile the Fc N-glycans of IgG samples from patients with gastric cancer (n = 80) and controls (n = 51) using LC-ESI-MS method to correlate the findings with stage of cancer and patients survival. Analysis of 32 different IgG N-glycans revealed significant increase of agalactosylated (GnGnF, GnGn(bi)F), and decrease of galactosylated (AGn(bi), AGn(bi)F, AA(bi), AAF) and monosialylated IgG glycoforms (NaAF, NaA(bi)) in cancer patients. A statistically significant increase of Fc fucosylation was observed in tumor stage II and III whereas reverse changes were found for the presence of bisecting GlcNAc. Higher level of fully sialylated glycans and elevated expression of glycans with bisecting GlcNAc were associated with better survival rate. Our findings provide the first evidence that the changes in Fc glycan profile may predict the survival of patients with gastric cancer. Cancer stage-dependent changes in Fc fucosylation and the bisecting N-acteylglucosamine expression as well as an association of several IgG glycoforms with the survival suggest that IgG glycosylation is related to pathogenesis of cancer and progression of the disease. PMID:22179780

  8. Concentrations of trace elements in American alligators (Alligator mississippiensis) from Florida, USA.

    PubMed

    Horai, Sawako; Itai, Takaaki; Noguchi, Takako; Yasuda, Yusuke; Adachi, Haruki; Hyobu, Yuika; Riyadi, Adi S; Boggs, Ashley S P; Lowers, Russell; Guillette, Louis J; Tanabe, Shinsuke

    2014-08-01

    Concentrations of 28 trace elements (Li, Mg, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Tl, Hg, Pb, and Bi) in the livers of juvenile and adult American alligators inhabiting two central Florida lakes, Lake Apopka (LA), and Lake Woodruff National Wildlife Refuge (LW) and one lagoon population located in Merritt Island National Wildlife Refuge (MINWR; NASA), were determined. In juveniles from MINWR, concentrations of nine elements (Li, Fe, Ni, Sr, In, Sb, Hg, Pb and Bi) were significantly higher, whereas six elements (V, Fe, As, Sr, Hg and Bi) were elevated in adults (p<0.05) obtained from MINWR. Significant enrichment of some trace elements in adults, relative to juveniles, was observed at all three sampling areas. Specifically, Fe, Pb and Hg were significantly elevated in adults when compared to juveniles, suggesting age-dependent accumulation of these elements. Further, As, Se and Sn showed the same trend but only in animals collected from MINWR. Mean Fe concentrations in the livers of adults from LA, LW and MINWR were 1770 μg g(-1) DW, 3690 μg g(-1) DW and 5250 μg g(-1) DW, respectively. More than half of the adult specimens from LW and MINWR exhibited elevated hepatic Fe concentrations that exceed the threshold value for toxic effects in donkey, red deer and human. These results prompted us to express our concern on possible exposure and health effects in American alligators by some trace elements derived from NASA activities. PMID:24698170

  9. Adjustment among mothers reporting same-gender sexual partners: a study of a representative population sample from Quebec Province (Canada).

    PubMed

    Julien, Danielle; Jouvin, Emilie; Jodoin, Emilie; L'archevêque, Alexandre; Chartrand, Elise

    2008-12-01

    We examined the well-being of mothers and non-mothers reporting exclusive opposite-gender sexual partners (OG), same-gender sexual partners (SG), or both (BI) in a representative sample of 20,773 participants (11,034 women) 15-years-old or older from the population of Quebec province in Canada. Participants completed a self-administered questionnaire and SG and BI women (n = 179) were matched to a sample of OG women (n = 179) based on age, income, geographical area, and children (having at least one 18-year-old or younger biological or adopted child at home). We assessed social milieu variables, risk factors for health disorders, mental health, and quality of mothers' relationship with children. The findings indicated a sexual orientation main effect: Mothers and non-mothers in the SG and BI group, as compared to their OG controls, were significantly less likely to live in a couple relationship, had significantly lower levels of social support, higher prevalence of early negative life events, substance abuse, suicide ideation, and higher levels of psychological distress. There were no Sexual Orientation X Parenthood status effects. The results further indicated that sexual orientation did not account for unique variance in women's psychological distress beyond that afforded by their social milieu, health risk factors, and parenthood status. No significant differences were found for the quality of mothers' relationship with children. SG-BI and OG mothers with low levels of social integration were significantly more likely to report problems with children than parents with high levels of social integration. We need to understand how marginal sexualities and their associated social stigma, as risk indicators for mothers, interact with other factors to impact family life, parenting skills, and children's adjustment. PMID:17665300

  10. Polymorphisms in the GAD2 gene-region are associated with susceptibility for unipolar depression and with a risk factor for anxiety disorders.

    PubMed

    Unschuld, Paul G; Ising, Marcus; Specht, Michael; Erhardt, Angelika; Ripke, Stephan; Heck, Angela; Kloiber, Stefan; Straub, Verica; Brueckl, Tanja; Müller-Myhsok, Bertram; Holsboer, Florian; Binder, Elisabeth B

    2009-12-01

    Glutamate decarboxylase (GAD) is the rate limiting enzyme for conversion of glutamic acid to gamma-aminobutyric acid (GABA). The GAD 65 kDa isoform is encoded by the gene GAD2 and is mainly expressed in synaptic terminals. It serves as an apoenzyme, which shows enhanced availability in situations of stress, responding to short-term demands for GABA. We analyzed 18 single nucleotide polymorphisms (SNPs) in the GAD2-gene region for associations with psychiatric diagnosis and behavioral inhibition (BI) derived from the personality traits neuroticism and extraversion as defined by the Eysenck Personality Questionaire (EPQ). A total of 268 patients with anxiety disorder (AD), 541 with unipolar depression (MD), and 541 healthy controls were included. We observe associations for five tag-SNPs with BI in the AD- and control samples as well as two additional case-control associations in the MD-sample. The associated SNPs lie within a 16KB linkage disequilibrium-block, including putative 5' GAD2-promoter-elements as well as the 3' end of the gene MYO3A. Using open access mRNA-expression data, we could show that BI-associated SNPs appear to be associated with differences in MYO3A- but not GAD2 lymphoblastoid-mRNA expression levels. These results support earlier studies that suggest associations of polymorphisms within the GAD2 locus with anxiety and affective disorders. However, data from expression studies imply that these polymorphisms could tag functional effects on the neighboring gene MYO3A, which is also expressed in the brain, including the cingulate cortex and the amygdala. PMID:19229853

  11. [Effect of temperature on decomposition of leachates by WAO/CWAO].

    PubMed

    Li, Hai-sheng; Liu, Liang; Li, Yu; Liu, Guang-hui; Wang, Jian; Liu, Hong-liang

    2004-07-01

    Catalytic wet air oxidation (CWAO) is a very effective physical chemistry method to treat organic wastewater. In this experiment, CWAO is employed to reduce the organic compounds in the landfill leachates. Temperature is an important factor in treating leachates by CWAO, so the effect of temperature on the reduction efficiency and decomposition rate of organic pollutants is investigated emphatically and the quantificational relationship is established between the decomposition rates and temperatures used in this study. The function of Co/Bi catalyst for the reduction of landfill leachates is also discussed. The influence of temperature on the degradation of landfill leachates by CWAO is carried out in a sealed environment using catalyst. The resulted information shows that the reduction rate of total organic carbon (TOC) and chemical oxygen demand (COD) increases notably with increase in temperature with or without the catalyst, and that the Elovich equation can describe dynamics course of landfill leachates degradation well. Rate constant k also increases with increase in temperature and the quantificational relationship is established between the rate constant k and temperature; the main reason of pH value reducing rapidly at first and later rising slowly is that a large amount of organic acid is produced in the early period in the reaction and the organic acid is degraded gradually later. Degradation of landfill leachates by CWAO can reach better treatment efficiency in gentle condition with catalyst Co/Bi in this study. The temperature's relatively great impact on the reaction using CWAO is discussed only in the paper and the effects of the other reaction conditions such as oxidant and catalyst dosage and the concentration of wastewater on degrading efficiency by CWAO are to be focused on. PMID:15515953

  12. Distribution of Bi Between Slags and Liquid Copper

    NASA Astrophysics Data System (ADS)

    Chen, Chunlin; Wright, Steven

    2016-06-01

    The distribution of Bi between liquid copper and calcium ferrite slag containing 24 wt pct CaO, iron silicate slag with 25 wt pct SiO2, and calcium iron silicate slags was measured at 1573 K (1300 °C) under controlled CO-CO2 atmosphere. The experimental results showed that bismuth distribution is affected by the oxygen partial pressure, and bismuth is likely to exist in slags in the 2+ oxidation state, i.e., as BiO. The distribution ratio between calcium ferrite slag and metal was found to be close to that of iron silicate slag. The Bi distribution ratio was found to decrease with increasing SiO2 and Al2O3 content in slag. Increasing temperature was found to decrease the Bi distribution ratio between slag and metal. Using the measured equilibrium data on Bi content of the metal and slag and composition dependence of the activity of Bi in liquid copper, the activity and hence activity coefficient of BiO in the slag was calculated. The close value of activity coefficient of BiO in both slags at the same oxygen partial pressure indicates that the CaO-BiO and SiO2-BiO interactions are likely to be at the same level, or the FeO x -BiO interaction is the predominant interaction for BiO in the slag. Therefore at a constant FeO x content in the slag, the CaO-BiO and SiO2-BiO interactions doesn't affect γ_{{BiO}} significantly.

  13. Anti-CD45 Pretargeted Radioimmunotherapy using Bismuth-213: High Rates of Complete Remission and Long-Term Survival in a Mouse Myeloid Leukemia Xenograft Model

    SciTech Connect

    Pagel, John M; Kenoyer, Aimee L; Back, Tom; Hamlin, Donald K; Wilbur, D Scott; Fisher, Darrell R; Park, Steven I; Frayo, Shani; Axtman, Amanda; Orgun, Nural; Orozoco, Johnnie; Shenoi, Jaideep; Lin, Yukang; Gopal, Ajay K; Green, Damian J; Appelbaum, Frederick R; Press, Oliver W

    2011-07-21

    Pretargeted radioimmunotherapy (PRIT) using an anti-CD45 antibody (Ab)-streptavidin (SA) conjugate and DOTA-biotin labeled with β-emitting radionuclides has been explored as a strategy to decrease relapse and toxicity. α-emitting radionuclides exhibit high cytotoxicity coupled with a short path-length, potentially increasing the therapeutic index and making them an attractive alternative to β-emitting radionuclides for patients with Acute Myeloid Leukemia (AML). Accordingly, we have used 213Bi in mice with human leukemia xenografts. Results demonstrated excellent localization of 213Bi-DOTA-biotin to tumors with minimal uptake into normal organs. After 10 minutes, 4.5 ± 1.1% of the injected dose of 213Bi was delivered per gram of tumor. α imaging demonstrated uniform radionuclide distribution within tumor tissue 45 minutes after 213Bi-DOTA-biotin injection. Radiation absorbed doses were similar to those observed using a β-emitting radionuclide (90Y) in the same model. We conducted therapy experiments in a xenograft model using a single-dose of 213Bi-DOTA-biotin given 24 hours after anti-CD45 Ab-SA conjugate. Among mice treated with anti-CD45 Ab-SA conjugate followed by 800 μCi of 213Bi- or 90Y-DOTA-biotin, 80% and 20%, respectively, survived leukemia-free for >100 days with minimal toxicity. These data suggest that anti-CD45 PRIT using an α-emitting radionuclide may be highly effective and minimally toxic for treatment of AML.

  14. Immunological properties of prolactin and studies on a gonadotropin binding inhibitor

    SciTech Connect

    Chang, Y.S.

    1985-01-01

    The physiological role of prolactin in horses has not yet been well defined. With the availability of highly purified ePRL for inducing antibody formation in rabbits and for radiolabeling with Na/sup 125/I, a very sensitive (0.4-0.6 ng/ml) and highly specific homologous RIA for ePRL was developed. A heterologous RIA using /sup 125/I-labeled ovine PRL and anti-ePRL antiserum was also developed and compared to the homologous RIA for ePRL. Of the two systems, it is concluded that this homologous RIA system is more suitable and more reliable for measuring prolactin concentration in horse serum samples. Until now, biochemical information on PRL has not been available for reptilian species. Sea turtle (Chelonia mydas) prolactin was purified from pituitary extracts by selective precipitation, DEAE-cellulose chromatography and gel filtration. Similar to other species of PRL, sea turtle PRL is a 22,000-24,000 daltons protein and contains a high content of glutamic acid, aspartic acid, serine and leucine, the N-terminal amino acid residue. Gonadotropin (FSH) binding inhibitor was partially purified from sheep testes by ammonium sulfate fractionation and ion exchange chromatography. The FSH-BI (molecular weight: 50,000 daltons, estimated by gel filtration) contains a protein moiety necessary for binding inhibitory activity. The inhibition of the binding of /sup 125/I-labeled ovine FSH to its receptor by the FSH-BI is not competitive. Both in vivo and in vitro biological studies of FSH-BI preparations in rats indicated various effects on FSH and LH activities at the gonadal level. These findings suggest a physiological role for FSH-BI in the regulation of reproduction.

  15. Experimental and modelling study of InGaBiAs/InP alloys with up to 5.8% Bi, and with Δso > Eg

    NASA Astrophysics Data System (ADS)

    Chai, Grace M. T.; Broderick, C. A.; O'Reilly, E. P.; Othaman, Z.; Jin, S. R.; Petropoulos, J. P.; Zhong, Y.; Dongmo, P. B.; Zide, J. M. O.; Sweeney, S. J.; Hosea, T. J. C.

    2015-09-01

    Temperature dependent photo-modulated reflectance is used to measure the band gap Eg and spin-orbit splitting energy Δso in dilute-Bi In0.53Ga0.47As1-xBix/InP for 1.2% ≤ x ≤ 5.8%. At room temperature, Eg decreases with increasing Bi from 0.65 to 0.47 eV (˜2.6 μm), while Δso increases from 0.42 to 0.62 eV, leading to a crossover between Eg and Δso around 3.8% Bi. The 5.8% Bi sample is the first example of this alloy where Δso > Eg has been confirmed at all temperatures. The condition Δso > Eg is important for suppressing hot-hole-producing non-radiative Auger recombination and inter-valence band absorption losses and so holds promise for the development of mid-infra-red devices based on this material system. The measured variations of Eg and Δso as a function of Bi content at 300 K are compared to those calculated using a 12-band k.p Hamiltonian which includes valence band anti-crossing effects. The Eg results as a function of temperature are fitted with the Bose-Einstein model. We also look for evidence to support the prediction that Eg in dilute bismides may show a reduced temperature sensitivity, but find no clear indication of that.

  16. Procalcitonin as a biomarker of bacterial infection in pediatric patients after congenital heart surgery

    PubMed Central

    Chakravarti, Sujata B; Reformina, Diane A; Lee, Timothy M; Malhotra, Sunil P; Mosca, Ralph S; Bhatla, Puneet

    2016-01-01

    Background: Bacterial infection (BI) after congenital heart surgery (CHS) is associated with increased morbidity and is difficult to differentiate from systemic inflammatory response syndrome caused by cardiopulmonary bypass (CPB). Procalcitonin (PCT) has emerged as a reliable biomarker of BI in various populations. Aim: To determine the optimal PCT threshold to identify BI among children suspected of having infection following CPB. Setting and Design: Single-center retrospective observational study. Materials and Methods: Medical records of all the patients admitted between January 2013 and April 2015 were reviewed. Patients in the age range of 0-21 years of age who underwent CHS requiring CPB in whom PCT was drawn between postoperative days 0-8 due to suspicion of infection were included. Statistical Analysis: The Wilcoxon rank-sum test was used for nonparametric variables. The diagnostic performance of PCT was evaluated using a receiver operating characteristic (ROC) curve. Results: Ninety-eight patients were included. The median age was 2 months (25th and 75th interquartile of 0.1-7.5 months). Eleven patients were included in the BI group. The median PCT for the BI group (3.42 ng/mL, 25th and 75th interquartile of 2.34-5.67) was significantly higher than the median PCT for the noninfected group (0.8 ng/mL, 25th and 75th interquartile 0.38-3.39), P = 0.028. The PCT level that yielded the best compromise between the sensitivity (81.8%) and specificity (66.7%) was 2 ng/mL with an area under the ROC curve of 0.742. Conclusion: A PCT less than 2 ng/mL makes BI unlikely in children suspected of infection after CHS. PMID:27212844

  17. Rodent model of direct cranial blast injury.

    PubMed

    Kuehn, Reed; Simard, Philippe F; Driscoll, Ian; Keledjian, Kaspar; Ivanova, Svetlana; Tosun, Cigdem; Williams, Alicia; Bochicchio, Grant; Gerzanich, Volodymyr; Simard, J Marc

    2011-10-01

    Traumatic brain injury resulting from an explosive blast is one of the most serious wounds suffered by warfighters, yet the effects of explosive blast overpressure directly impacting the head are poorly understood. We developed a rodent model of direct cranial blast injury (dcBI), in which a blast overpressure could be delivered exclusively to the head, precluding indirect brain injury via thoracic transmission of the blast wave. We constructed and validated a Cranium Only Blast Injury Apparatus (COBIA) to deliver blast overpressures generated by detonating .22 caliber cartridges of smokeless powder. Blast waveforms generated by COBIA replicated those recorded within armored vehicles penetrated by munitions. Lethal dcBI (LD(50) ∼ 515 kPa) was associated with: (1) apparent brainstem failure, characterized by immediate opisthotonus and apnea leading to cardiac arrest that could not be overcome by cardiopulmonary resuscitation; (2) widespread subarachnoid hemorrhages without cortical contusions or intracerebral or intraventricular hemorrhages; and (3) no pulmonary abnormalities. Sub-lethal dcBI was associated with: (1) apnea lasting up to 15 sec, with transient abnormalities in oxygen saturation; (2) very few delayed deaths; (3) subarachnoid hemorrhages, especially in the path of the blast wave; (4) abnormal immunolabeling for IgG, cleaved caspase-3, and β-amyloid precursor protein (β-APP), and staining for Fluoro-Jade C, all in deep brain regions away from the subarachnoid hemorrhages, but in the path of the blast wave; and (5) abnormalities on the accelerating Rotarod that persisted for the 1 week period of observation. We conclude that exposure of the head alone to severe explosive blast predisposes to significant neurological dysfunction. PMID:21639724

  18. Mobile Brain/Body Imaging (MoBI) of Physical Interaction with Dynamically Moving Objects

    PubMed Central

    Jungnickel, Evelyn; Gramann, Klaus

    2016-01-01

    The non-invasive recording and analysis of human brain activity during active movements in natural working conditions is a central challenge in Neuroergonomics research. Existing brain imaging approaches do not allow for an investigation of brain dynamics during active behavior because their sensors cannot follow the movement of the signal source. However, movements that require the operator to react fast and to adapt to a dynamically changing environment occur frequently in working environments like assembly-line work, construction trade, health care, but also outside the working environment like in team sports. Overcoming the restrictions of existing imaging methods would allow for deeper insights into neurocognitive processes at workplaces that require physical interactions and thus could help to adapt work settings to the user. To investigate the brain dynamics accompanying rapid volatile movements we used a visual oddball paradigm where participants had to react to color changes either with a simple button press or by physically pointing towards a moving target. Using a mobile brain/body imaging approach (MoBI) including independent component analysis (ICA) with subsequent backprojection of cluster activity allowed for systematically describing the contribution of brain and non-brain sources to the sensor signal. The results demonstrate that visual event-related potentials (ERPs) can be analyzed for simple button presses and physical pointing responses and that it is possible to quantify the contribution of brain processes, muscle activity and eye movements to the signal recorded at the sensor level even for fast volatile arm movements with strong jerks. Using MoBI in naturalistic working environments can thus help to analyze brain dynamics in natural working conditions and help improving unhealthy or inefficient work settings. PMID:27445747

  19. Rapid determination of (210)Pb and (210)Po in water and application to marine samples.

    PubMed

    Villa-Alfageme, M; Mas, J L; Hurtado-Bermudez, S; Masqué, P

    2016-11-01

    Measurement of radionuclides in marine samples, specifically radioactive pairs disequilibrium, has gained interest lately due to their ability to trace cutting edge biogeochemical processes. In this context, we developed a fast, direct method for determining (210)Pb and (210)Po water through the use of ultra low-level liquid scintillation counting and alpha-particle spectrometry respectively and through Eichrom Sr resins for the Po-Pb separation. For (210)Pb analysis, the method uses stable lead as a yield tracer measured by a robust ICP-MS technique, and (210)Po is determined through self-deposition using the conventional (209)Po yield tracer. The improvements of the method over other techniques are: a) the analysis can be completed within 6 days, simplifying other methods, b) very low limits of detection have been achieved -0.12 and 0.005mBqL(-1) for (210)Pb and (210)Po, respectively - and c) most of the method could be carried out in on-board analysis. We applied the method to different aqueous samples and specifically to marine samples. We determined (210)Pb and (210)Po in the dissolved fraction of Mediterranean Sea water and an estuary at the South-West of Spain. We found that it can be successfully employed to marine samples but we recommend to i) use a minimum of 20L water to measure the (210)Pb in the dissolved phase by LSC and lower volumes to measure total concentrations; ii) wait for (210)Pb and (210)Bi in secular equilibrium and measure the total spectrum to minimise the limit of detection and improve accuracy. PMID:27591584

  20. Identification of the Molecular Target of Small Molecule Inhibitors of HDL Receptor SR-BI Activity†,‡,§

    PubMed Central

    Nieland, Thomas J. F.; Shaw, Jared T.; Jaipuri, Firoz A.; Duffner, Jay L.; Koehler, Angela N.; Banakos, Sotirios; Zannis, Vassilis I.; Kirchhausen, Tomas; Krieger, Monty

    2009-01-01

    Scavenger receptor, class B, type I (SR-BI), controls high-density lipoprotein (HDL) metabolism by mediating cellular selective uptake of lipids from HDL without the concomitant degradation of the lipoprotein particle. We previously identified in a high-throughput chemical screen of intact cells five compounds (BLT-1–5) that inhibit SR-BI-dependent lipid transport from HDL, but do not block HDL binding to SR-BI on the cell surface. Although these BLTs are widely used to examine the diverse functions of SR-BI, their direct target(s), SR-BI itself or some other component of the SR-BI pathway, has not been identified. Here we show that SR-BI in the context of a membrane lipid environment is the target of BLT-1, -3, -4, and -5. The analysis using intact cells and an in vitro system of purified SR-BI reconstituted into liposomes was aided by information derived from structure–activity relationship (SAR) analysis of the most potent of these BLTs, the thiosemicarbazone BLT-1. We found that the sulfur atom of BLT-1 was crucially important for its inhibitory activity, because changing it to an oxygen atom resulted in the isostructural, but essentially inactive, semicarbazone derivative BLT-1sc. SAR analysis also established the importance of BLT-1’s hydrophobic tail. BLTs and their corresponding inactive compounds can be used to explore the mechanism and function of SR-BI-mediated selective lipid uptake in diverse mammalian experimental models. Consequently, BLTs may help determine the therapeutic potential of SR-BI-targeted pharmaceutical drugs. PMID:18067275

  1. Separation and Extraction of Bismuth and Manganese from Roasted Low-Grade Bismuthinite and Pyrolusite: Thermodynamic Analysis and Sulfur Fixing

    NASA Astrophysics Data System (ADS)

    Zhan, Jing; Wang, Zhi-Jian; Zhang, Chuan-Fu; Hwang, Jiann-Yang; Xia, Chu-Ping

    2015-05-01

    A new environmentally friendly technology with higher recovery of bismuth is proposed to extract bismuth from low-grade bismuthinite and co-production MnSO4 from low-grade pyrolusite. The effects of simultaneous roasting process parameters on the sulfur-fixing rate and MnSO4 formation rate are investigated. Based on the Pourbaix diagram of metal-sulfur-oxygen system, the behavior of bismuth, manganese, and associated metal elements such ferrous, copper, lead, and sulfur in the bismuthinite and pyrolusite during roasting process is analyzed. The experimental results show that Bi in the ores can be converted into bismuth oxide or oxygen bismuth sulfate, and most of Mn in the ores can react with SO2 from bismuthinite to form MnSO4, which agree with thermodynamic analysis. A maximum of sulfur-fixing rate of 98.14% and MnSO4 formation rate of 70.2% are obtained under the conditions of 1.4 for the molar ratio of MnO2 to total sulfur in mixing ores of bismuthinite and pyrolusite ( n(MnO2)/ n(S)), 923 K for the roasting temperature, 2 h for roasting time, 140 L/h for air rate, and less than 74 μm for particle size. The ultimate recovery rate of bismuth reaches 96.25% by selective leaching of the roasted product, purification of leaching solution, and hydrolysis, which is higher than the current applied technology for the low-grade bismuthinite.

  2. Converting an AEG Cyclotron to H- Acceleration and Extraction

    NASA Astrophysics Data System (ADS)

    Ramsey, Fred; Carroll, Lewis; Rathmann, Tom; Huenges, Ernst; Bechtold, Matthias Mentler Volker

    2009-03-01

    Clinical Trials are under way to evaluate agents labeled with the nuclide 225Ac and its decay product 213Bi, in targeted alpha-immuno-therapy [1]. 225Ac can be produced on a medium-energy cyclotron via the nuclear reaction 226Ra(p,n)225Ac. To demonstrate proof-of-principle, a vintage AEG cyclotron, Model E33 [2], with an internal target, had been employed in a pilot production program at the Technical University of Munich (TUM). To enhance production capability and further support the clinical studies, the TUM facility has recently been refurbished and upgraded, adding a new external beam-line, automated target irradiation and transport systems, new laboratories, hot cells, etc. [3]. An improved high-power rotating target has been built and installed [4]. The AEG cyclotron itself has also been modified and upgraded to accelerate and extract H- ions. We have designed, built, and tested a new axial Penning-type ion source which is optimized for the production of H- ions. The ion source has continued to evolve through experiment and experience. Steady improvements in materials and mechanics have led to enhanced source stability, life-time, and H- production. We have also designed and built a precision H- charge-exchange beam-extraction system which is equipped with a vacuum lock. To fit within the tight mechanical constraint imposed by the narrow magnet gap, the system incorporates a novel chain-drive foil holder and foil-changer mechanism. The reconfigured cyclotron system has now been in operation for more than 1 year. Three long-duration target irradiations have been conducted. The most recent bombardment ran 160 continuous hours at a beam on target of ˜80 microamperes for a total yield of ˜70 milli-curies of 225Ac.

  3. Tight-binding analysis of the electronic structure of dilute bismide alloys of GaP and GaAs

    NASA Astrophysics Data System (ADS)

    Usman, Muhammad; Broderick, Christopher A.; Lindsay, Andrew; O'Reilly, Eoin P.

    2011-12-01

    We develop an atomistic, nearest-neighbor sp3s* tight-binding Hamiltonian to investigate the electronic structure of dilute bismide alloys of GaP and GaAs. Using this model, we calculate that the incorporation of dilute concentrations of Bi in GaP introduces Bi-related defect states in the band gap, which interact with the host matrix valence band edge via a Bi composition dependent band anticrossing (BAC) interaction. By extending this analysis to GaBixAs1-x, we demonstrate that the observed strong variation of the band gap (Eg) and spin-orbit-splitting energy (ΔSO) with Bi composition can be well explained in terms of a BAC interaction between the extended states of the GaAs valence band edge and highly localized Bi-related defect states lying in the valence band, with the change in Eg also having a significant contribution from a conventional alloy reduction in the conduction band edge energy. Our calculated values of Eg and ΔSO are in good agreement with experiment throughout the investigated composition range (x≤13%). In particular, our calculations reproduce the experimentally observed crossover to an Eg<ΔSO regime at approximately 10.5% Bi composition in bulk GaBixAs1-x. Recent x-ray spectroscopy measurements have indicated the presence of Bi pairs and clusters even for Bi compositions as low as 2%. We include a systematic study of different Bi nearest-neighbor environments in the alloy to achieve a quantitative understanding of the effect of Bi pairing and clustering on the GaBixAs1-x electronic structure.

  4. Impact of alloy disorder on the band structure of compressively strained GaBixAs1-x

    NASA Astrophysics Data System (ADS)

    Usman, Muhammad; Broderick, Christopher A.; Batool, Zahida; Hild, Konstanze; Hosea, Thomas J. C.; Sweeney, Stephen J.; O'Reilly, Eoin P.

    2013-03-01

    The incorporation of bismuth (Bi) in GaAs results in a large reduction of the band gap energy (Eg) accompanied with a large increase in the spin-orbit splitting energy (△SO), leading to the condition that △SO>Eg, which is anticipated to reduce hot-hole producing Auger recombination losses whereby the energy and momentum of a recombining electron-hole pair are given to a second hole which is excited into the spin-orbit band. We theoretically investigate the electronic structure of experimentally grown GaBixAs1-x samples on (100) GaAs substrates by directly comparing our data with room temperature photomodulated reflectance (PR) measurements. Our atomistic theoretical calculations, in agreement with the PR measurements, confirm that Eg is equal to △SO for x≈ 9%. We then theoretically probe the inhomogeneous broadening of the interband transition energies as a function of the alloy disorder. The broadening associated with spin-split-off transitions arises from conventional alloy effects, while the behavior of the heavy-hole transitions can be well described using a valence band-anticrossing model. We show that for the samples containing 8.5% and 10.4% Bi the difficulty in identifying a clear light-hole-related transition energy from the measured PR data is due to the significant broadening of the host matrix light-hole states as a result of the presence of a large number of Bi resonant states in the same energy range and disorder in the alloy. We further provide quantitative estimates of the impact of supercell size and the assumed random distribution of Bi atoms on the interband transition energies in GaBixAs1-x. Our calculations support a type-I band alignment at the GaBixAs1-x/GaAs interface, consistent with recent experimental findings.

  5. Increased DNA methylation of scavenger receptor class B type I contributes to inhibitory effects of prenatal caffeine ingestion on cholesterol uptake and steroidogenesis in fetal adrenals

    SciTech Connect

    Wu, Dong-Mei; He, Zheng; Ma, Liang-Peng; Wang, Lin-Long; Ping, Jie; Wang, Hui

    2015-06-01

    Steroid hormones synthesized from cholesterol in the fetal adrenal are crucial for fetal development. We have observed the inhibited fetal adrenal corticosterone synthesis and increased intrauterine growth retardation (IUGR) rate in rats under prenatal caffeine ingestion. The aim of this study is to evaluate the effects of prenatal caffeine ingestion on cholesterol supply in fetal adrenal steroidogenesis in rats and explore the underlying epigenetic mechanisms. Pregnant Wistar rats were treated with 60 mg/kg·d caffeine from gestational day (GD) 7 to GD17. Histological changes of fetal adrenals and increased IUGR rates were observed in the caffeine group. There were significantly decreased steroid hormone contents and cholesterol supply in caffeine-treated fetal adrenals. Data from the gene expression array suggested that prenatal caffeine ingestion caused increased expression of genes related to DNA methylation and decreased expression of genes related to cholesterol uptake. The following conjoint analysis of DNA methylation array with these differentially expressed genes suggested that scavenger receptor class B type I (SR-BI) may play an important role in caffeine-induced cholesterol supply deficiency. Moreover, real-time RT-PCR and immunohistochemical detection certified the inhibitory effects of caffeine on both mRNA expression and protein expression of SR-BI in the fetal adrenal. And the increased DNA methylation frequency in the proximal promoter of SR-BI was confirmed by bisulfite-sequencing PCR. In conclusion, prenatal caffeine ingestion can induce DNA hypermethylation of the SR-BI promoter in the rat fetal adrenal. These effects may lead to decreased SR-BI expression and cholesterol uptake, which inhibits steroidogenesis in the fetal adrenal. - Highlights: • Prenatal caffeine ingestion inhibits steroid hormone production in the fetal adrenal. • Prenatal caffeine ingestion inhibits cholesterol uptake in the fetal adrenal. • Prenatal caffeine

  6. Formation and phase transformation of Bi-containing QD-like clusters in annealed GaAsBi

    NASA Astrophysics Data System (ADS)

    Wu, Mingjian; Luna, Esperanza; Puustinen, Janne; Guina, Mircea; Trampert, Achim

    2014-05-01

    We report the formation and phase transformation of Bi-containing clusters in \\text{GaA}{{\\text{s}}_{1-x}} Bi_{x} epilayers upon annealing. The \\text{GaA}{{\\text{s}}_{1-x}} Bi_{x} layers were grown by molecular beam epitaxy under low (220 ^{{}^\\circ }\\text{C}) and high (315 ^{{}^\\circ }\\text{C}) temperatures and subsequently annealed using different temperatures and annealing times. Bi-containing clusters were identified only in the annealed samples that were grown at low temperature, revealing a relatively homogeneous size distribution. Depending on the annealing temperature and duration, the clusters show different sizes ranging from 5 to 20 nm, as well as different crystallographic phase, being coherently strained zincblende \\text{GaA}{{\\text{s}}_{1-x}} Bi_{x} (zb Bi-rich Ga(As, Bi)) clusters or rhombohedral pure Bi (rh-Bi) clusters. We found that: (1) the formation of the zb Bi-rich Ga(As, Bi) clusters is driven by the intrinsic tendency of the alloy to phase separately and is mediated by the native point defects present in the low temperature grown epilayers; (2) the phase transformation from zb Bi-rich Ga(As, Bi) to rh-Bi nucleates in zincblende {111} planes and grows until total consumption of Bi in the GaAs matrix. We propose a model accounting for the formation and phase transformation of Bi-containing clusters in this system. Furthermore, our study reveals the possibility to realize self-organized zb Bi-rich Ga(As, Bi) clusters that can exhibit QD-like features.

  7. Diffuse scattering from the liquid-vapor interfaces of dilute Bi:Ga, Tl:Ga, and Pb:Ga alloys

    SciTech Connect

    Li, Dongxu; Jiang, Xu; Lin, Binhua; Meron, Mati; Rice, Stuart A.

    2010-07-19

    As part of a study of the in-plane wave-vector (q{sub xy}) dependence of the effective Hamiltonian for the liquid-vapor interface, H(q), the wave-vector dependences of diffuse x-ray scattering from the liquid-vapor interfaces of dilute alloys of Bi in Ga, Tl in Ga, and Pb in Ga have been measured. In these dilute alloys the solute component segregates as a monolayer that forms the outermost stratum of the liquid-vapor interfaces, and the density distribution along the normal to the interface is stratified. Over the temperature ranges that the alloy interfaces were studied, the Tl and Pb monolayers exhibit both crystalline and liquid phases while the Bi monolayer is always liquid. The diffuse scattering from the liquid-vapor interfaces of these alloys displays interesting differences with that from the liquid-vapor interface of pure Ga. The presence of a segregated monolayer of solute in the liquid-vapor interface of the alloy appears to slightly suppress the fluctuations in an intermediate wave-vector range in a fashion that preserves the validity of the macroscopic capillary wave model to smaller wavelengths than in pure liquid Ga, and there is an increase in diffuse scattering when the Tl and Pb monolayers melt. The surface intrinsic roughness from fitting the wave-vector dependence of surface tension is 5.0 pm for the Tl:Ga alloy and 1.4 pm for the Bi:Ga alloy. Also, a mode of excitation that contributes to diffuse scattering from the liquid-vapor interface of Pb in Ga, but does not contribute to diffuse scattering from the liquid-vapor interface of Ga, has been identified. It is proposed that this mode corresponds to the separation of the Pb and Ga layers in the regime 1 nm{sup -1} {le} q{sub xy} {le} 10 nm{sup -1}.

  8. Detailed photonuclear cross-section calculations and astrophysical applications

    SciTech Connect

    Gardner, D.G.; Gardner, M.A.; Hoff, R.W.

    1989-06-15

    We have investigated the role of an isomeric state and its coupling to the ground state (g.s.) via photons and neutron inelastic scattering in a stellar environment by making detailed photonuclear and neutron cross-section calculations for /sup 176/Lu and /sup 210/Bi. In the case of /sup 176/Lu, the g.s. would function as an excellent galactic slow- (s-) process chronometer were it not for the 3.7-h isomer at 123 keV. Our calculations predicted much larger photon cross sections for production of the isomer, as well as a lower threshold, than had been assumed based on earlier measurements. These two factors combine to indicate that an enormous correction, a factor of 10/sup 7/, must be applied to shorten the current estimate of the half-life against photoexcitation of /sup 176/Lu as a function of temperature. This severely limits the use of /sup 176/Lu as a stellar chronometer and indicates a significantly lower temperature at which the two states reach thermal equilibrium. For /sup 210/Bi, our preliminary calculations of the production and destruction of the 3 /times/ 10/sup 6/ y isomeric state by neutrons and photons suggest that the /sup 210/Bi isomer may not be destroyed by photons as rapidly as assumed in certain stellar environments. This leads to an alternate production path of /sup 207/Pb and significantly affects presently interpreted lead isotopic abundances. We have been able to make such detailed nuclear cross-section calculations using: modern statistical-model codes of the Hauser-Feshbach type, with complete conservation of angular momentum and parity; reliable systematics of the input parameters required by these codes, including knowledge of the absolute gamma-ray strength-functions for E1, M1, and E2 transitions; and codes developed to compute large, discrete, nuclear level sets, their associated gamma-ray branchings, and the presence and location of isomeric states. 7 refs., 2 figs.

  9. Arsenic, Sb and Bi contamination of soils, plants, waters and sediments in the vicinity of the Dalsung Cu-W mine in Korea.

    PubMed

    Jung, Myung Chae; Thornton, Iain; Chon, Hyo-Taek

    2002-08-01

    The objective of this study is to investigate environmental contamination derived from metalliferous mining activities. In the study area, the Dalsung Cu-W mine, soils, various crop plants, stream waters, sediments and particulates were sampled in and around the mine and analyzed for As, Sb and Bi by ICP-AES with a hydride generator. In addition, soil pH, cation exchange capacity, loss-on-ignition and soil texture were also measured. Concentrations of As, Sb and Bi in surface soils sampled in the mine dump sites averaged 2500, 54 and 436 microg g(-1), respectively. Relatively lower concentrations, however, were found in soils from alluvial and high land sites and household garden sites. Arsenic, Sb and Bi contents in plant samples varied depending upon their species and parts, with higher concentrations in spring onions, soybean leaves and perilla leaves and lower levels in red peppers, corn grains and jujube grains. These results confirm that elemental concentrations in plant leaves are much higher than those in plant grain. Elevated levels of As, Sb and Bi were also found in stream sediments sampled in the vicinity of the mine and decreased with distance from the mine. Concentrations in stream water samples ranged from 0.8 to 19.1 microg As l(-1) and from 0.3 to 8.4 microg Bi l(-1); all the samples contained less than 1.0 microg Sb l(-1). Because of very low particulate loading at the time of sampling, the metal contents in particulates were very low (< 8.2 microg As l(-1), < 0.22 microg Sb l(-1) and 2.8 microg Bi l(-1). This may be mainly due to the low solubility of those elements under moderately acidic and oxidizing conditions of the mining area. PMID:12186294

  10. Predicting bromide incorporation in a chlorinated indoor swimming pool.

    PubMed

    Chowdhury, Shakhawat; Mazumder, Abu Jafar; Husain, Tahir

    2016-06-01

    The water in and air above swimming pools often contain high levels of disinfection byproducts (DBPs) due to chemical reactions between chlorine- or bromine-based disinfectants and organic/inorganic matter in the source water and released from swimmers. Exposure to these DBPs, though inevitable, can pose health threats to humans. In this study, DBPs in tap water (S1), and water from a chlorinated indoor swimming pool before (S2) and after swimming (S3) were measured. The brominated species constituted the majority of DBPs formed in S1, S2, and S3. Trihalomethanes (THMs) in S3 was 6.9 (range 2.9-11.1) and 1.4 (range 0.52-2.9) times those in S1 and S2, respectively; and the haloacetic acids (HAAs) in S3 was 4.2 (range 2.5-7.5) and 1.2 (range 0.6-2.6) times those in S1 and S2, respectively. The mean THMs in air above the swimming pool before (S2-A) and after swimming (S3-A) were 72.2 and 93.0 μg/m(3), respectively, and their ranges were 36.3-105.8 and 44.1-133.6 μg/m(3), respectively. The average percentages of bromide incorporation (BI) into THMs in S1, S2, and S3 were 3.0, 9.3, and 10.6 %, respectively; and the BI into HAAs in S1, S2, and S3 were 6.6, 12.0, and 12.2 %, respectively. Several models were trained for predicting the BI into THMs and HAAs. The results indicate that additional information is required to develop predictive models for BI in swimming pools. PMID:26971516

  11. Trace metals in bulk precipitation and throughfall in a suburban area of Japan

    NASA Astrophysics Data System (ADS)

    Hou, H.; Takamatsu, T.; Koshikawa, M. K.; Hosomi, M.

    Throughfall and bulk precipitation samples were collected monthly for 1.5 years over bare land and under canopies of Japanese cedar ( Cryptomeria japonica), Japanese red pine ( Pinus densiflora), Japanese cypress ( Chamaecyparis obtusa), and bamboo-leafed oak ( Quercus myrsinaefolia) in a suburban area of Japan. Samples were analyzed for dissolved Al, Mn, Fe, Cu, Zn, Ag, In, Sn, Sb and Bi by ICP-AES and ICP-MS. The metal concentrations were higher in throughfall, especially that of C. japonica, than bulk precipitation. Enrichment ratios (ERs: ratios of metal concentrations in throughfall to those in bulk precipitation) ranged from 2.5 (Zn) to 5.3 (Ag) (3.9 on average), and ERs for slightly soluble metals were generally higher than those for easily soluble metals. Concentrations of Mn, Fe, Cu, and Zn accounted for 99% of the total concentration of heavy metals in rainwater, whereas those of rare metals such as Ag, In, Sn, and Bi totaled <0.23%. Average concentrations of rare metals were 0.002 and 0.010 μg l -1 for Ag, 0.001 and 0.005 μg l -1 for In, 0.062 and 0.21 μg l -1 for Sn, and 0.006 and 0.023 μg l -1 for Bi in bulk precipitation and throughfall, respectively. The metal concentrations in rainwater were negatively correlated to the volume of rainwater, indicating that washout is the main mechanism that incorporates metals into rainwater. From the enrichment factors, that is, (X/Al) rain/(X/Al) crust, metals other than Fe were shown to be more enriched in rainwater than in the Earth's crust, including those present as a result of leaching from soil dust (Mn) and from anthropogenic sources (Cu, Zn, Ag, In, Sn, Sb, and Bi).

  12. Functional and Biochemical Characterization of Hepatitis C Virus (HCV) Particles Produced in a Humanized Liver Mouse Model.

    PubMed

    Calattini, Sara; Fusil, Floriane; Mancip, Jimmy; Dao Thi, Viet Loan; Granier, Christelle; Gadot, Nicolas; Scoazec, Jean-Yves; Zeisel, Mirjam B; Baumert, Thomas F; Lavillette, Dimitri; Dreux, Marlène; Cosset, François-Loïc

    2015-09-18

    Lipoprotein components are crucial factors for hepatitis C virus (HCV) assembly and entry. As hepatoma cells producing cell culture-derived HCV (HCVcc) particles are impaired in some aspects of lipoprotein metabolism, it is of upmost interest to biochemically and functionally characterize the in vivo produced viral particles, particularly regarding how lipoprotein components modulate HCV entry by lipid transfer receptors such as scavenger receptor BI (SR-BI). Sera from HCVcc-infected liver humanized FRG mice were separated by density gradients. Viral subpopulations, termed HCVfrg particles, were characterized for their physical properties, apolipoprotein association, and infectivity. We demonstrate that, in contrast to the widely spread distribution of apolipoproteins across the different HCVcc subpopulations, the most infectious HCVfrg particles are highly enriched in apoE, suggesting that such apolipoprotein enrichment plays a role for entry of in vivo derived infectious particles likely via usage of apolipoprotein receptors. Consistent with this salient feature, we further reveal previously undefined functionalities of SR-BI in promoting entry of in vivo produced HCV. First, unlike HCVcc, SR-BI is a particularly limiting factor for entry of HCVfrg subpopulations of very low density. Second, HCVfrg entry involves SR-BI lipid transfer activity but not its capacity to bind to the viral glycoprotein E2. In conclusion, we demonstrate that composition and biophysical properties of the different subpopulations of in vivo produced HCVfrg particles modulate their levels of infectivity and receptor usage, hereby featuring divergences with in vitro produced HCVcc particles and highlighting the powerfulness of this in vivo model for the functional study of the interplay between HCV and liver components. PMID:26224633

  13. Past and present levels of some radionuclides in fish from Bikini and Enewetak atolls

    SciTech Connect

    Noshkin, V.E.; Robison, W.L.; Brunk, J.L.

    1997-07-01

    Bikini and Enewetak were the sites in the Northern Marshall Islands that were used by the United States as testing grounds for nuclear devices between 1946 and 1958. The testing produced close-in fallout debris that was contaminated with different radionuclides and which entered the aquatic environment. The contaminated lagoon sediments became a reservoir and source term of manmade radionuclides for the resident marine organisms. This report contains a summary of all the available data on the concentrations of {sup 137}Cs {sup 60}Co and {sup 217}Bi in flesh samples of reef and pelagic fish collected from Bikini and Enewetak Atolls between 1964 and 1995. The selection of these three radionuclides for discussion is based on the fact that these are the only radionuclides that have been routinely detected by gamma spectrometry in flesh samples from all fish for the last 20 y. Flesh from fish is an important source of food in the Marshallese diet. These radionuclides along with the transuranic radionuclides and {sup 90}Sr contribute most of the small radiological dose from ingesting marine foods. Some basic relationships among concentrations in different tissues and organs are discussed. The reef fish can be used as indicator species because their body burden is derived from feeding, over a lifetime, within a relatively small contaminated area of the lagoon. Therefore, the emphasis of this report is to use this extensive and unique concentration data base to describe the effective half lives and cycling for the radionuclides in the marine environments during the 31-y period between 1964 and 1995. 26 refs., 4 figs., 5 tabs.

  14. Intestinal scavenger receptors are involved in vitamin K1 absorption.

    PubMed

    Goncalves, Aurélie; Margier, Marielle; Roi, Stéphanie; Collet, Xavier; Niot, Isabelle; Goupy, Pascale; Caris-Veyrat, Catherine; Reboul, Emmanuelle

    2014-10-31

    Vitamin K1 (phylloquinone) intestinal absorption is thought to be mediated by a carrier protein that still remains to be identified. Apical transport of vitamin K1 was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium and in transfected HEK cells. Phylloquinone uptake was then measured ex vivo using mouse intestinal explants. Finally, vitamin K1 absorption was compared between wild-type mice and mice overexpressing scavenger receptor class B type I (SR-BI) in the intestine and mice deficient in cluster determinant 36 (CD36). Phylloquinone uptake by Caco-2 cells was saturable and was significantly impaired by co-incubation with α-tocopherol (and vice versa). Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 85% of vitamin K1 uptake. BLT1 also decreased phylloquinone apical efflux by ∼80%. Transfection of HEK cells with SR-BI and CD36 significantly enhanced vitamin K1 uptake, which was subsequently decreased by the addition of BLT1 or sulfo-N-succinimidyl oleate (CD36 inhibitor), respectively. Similar results were obtained in mouse intestinal explants. In vivo, the phylloquinone postprandial response was significantly higher, and the proximal intestine mucosa phylloquinone content 4 h after gavage was increased in mice overexpressing SR-BI compared with controls. Phylloquinone postprandial response was also significantly increased in CD36-deficient mice compared with wild-type mice, but their vitamin K1 intestinal content remained unchanged. Overall, the present data demonstrate for the first time that intestinal scavenger receptors participate in the absorption of dietary phylloquinone. PMID:25228690

  15. Intestinal Scavenger Receptors Are Involved in Vitamin K1 Absorption*

    PubMed Central

    Goncalves, Aurélie; Margier, Marielle; Roi, Stéphanie; Collet, Xavier; Niot, Isabelle; Goupy, Pascale; Caris-Veyrat, Catherine; Reboul, Emmanuelle

    2014-01-01

    Vitamin K1 (phylloquinone) intestinal absorption is thought to be mediated by a carrier protein that still remains to be identified. Apical transport of vitamin K1 was examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium and in transfected HEK cells. Phylloquinone uptake was then measured ex vivo using mouse intestinal explants. Finally, vitamin K1 absorption was compared between wild-type mice and mice overexpressing scavenger receptor class B type I (SR-BI) in the intestine and mice deficient in cluster determinant 36 (CD36). Phylloquinone uptake by Caco-2 cells was saturable and was significantly impaired by co-incubation with α-tocopherol (and vice versa). Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 85% of vitamin K1 uptake. BLT1 also decreased phylloquinone apical efflux by ∼80%. Transfection of HEK cells with SR-BI and CD36 significantly enhanced vitamin K1 uptake, which was subsequently decreased by the addition of BLT1 or sulfo-N-succinimidyl oleate (CD36 inhibitor), respectively. Similar results were obtained in mouse intestinal explants. In vivo, the phylloquinone postprandial response was significantly higher, and the proximal intestine mucosa phylloquinone content 4 h after gavage was increased in mice overexpressing SR-BI compared with controls. Phylloquinone postprandial response was also significantly increased in CD36-deficient mice compared with wild-type mice, but their vitamin K1 intestinal content remained unchanged. Overall, the present data demonstrate for the first time that intestinal scavenger receptors participate in the absorption of dietary phylloquinone. PMID:25228690

  16. Comparative thermoresistance of two biological indicators for monitoring steam autoclaves. 3. Comparison performed at 121 degrees C in a hospital prevacuum steam sterilizer.

    PubMed

    Skaug, N; Kalager, T

    1986-04-01

    According to Pharmacopoea Nordica, steam autoclaves should be regularly monitored by a specific Swedish preparation of Bacillus stearothermophilus spores. If another biological indicator (BI) is used for such a control, it should first be calibrated against the Swedish BI (SBI) and the two BIs should be equally thermoresistant. Attest No. 1262 BI (ABI) has previously been shown to be more thermoresistant than the SBI at 134 degrees C, saturated steam. The purpose of the present study was to compare the thermoresistance of the SBI and the ABI at 121 degrees C, saturated steam and prevacuum. Seven hundred and twenty units of each BI were heat-exposed in an Emmer 760 litre prevacuum, pressure-pulsing steam autoclave. After prevacuum with steam injection (manual or automatic preconditioning), the following incremental heat exposure times were used in triplicate (20 simultaneously tested units of each BI in each cycle) according to a randomized scheme: 5, 6 1/2, 8, 9 1/2, 11, 12 1/2, 14 and 15 min. The intra-chamber pressure and temperature were continuously monitored throughout the test and equilibration cycles. The heat-exposed BI units were cultivated and read as recommended by the manufacturers. SBI and ABI showed a survival-time of 8 min and 11 min respectively, and a kill-time between 14 min and 15 min for both BIs. Thus, the ABI had the narrower survival-kill window. Probit analysis testing of the results showed that the difference in thermoresistance, at 121 degrees C, saturated steam and prevacuum between Attest No. 1262 BI and the Swedish BI mentioned in Pharmacopea Nordica was not statistically significant. PMID:3728026

  17. Synthesis and structure of N,C-chelated organoantimony(v) and organobismuth(v) compounds.

    PubMed

    Urbanová, Iva; Jambor, Roman; Růžička, Aleš; Jirásko, Robert; Dostál, Libor

    2014-01-14

    The reaction of N,C-intramolecularly coordinated organoantimony(iii) and organobismuth(iii) compounds LMCl2 (M = Sb () or Bi () and L = [o-(CH[double bond, length as m-dash]N-2,6-iPr2C6H3)C6H4]) with phenyllithium in a 1 : 1 or 1 : 2 molar ratio gave compounds LM(Ph)Cl (M = Sb () or Bi ()) and LMPh2 (M = Sb () or Bi ()) in moderate to good yields. Compound could also be prepared by the treatment of the lithium compound LLi with in situ prepared PhSbCl2. Oxidation of the antimony(iii) compounds , and with one equivalent of SO2Cl2 proceeded smoothly with formation of organoantimony(v) compounds LSbCl4 (), LSb(Ph)Cl3 () and LSbPh2Cl2 () in nearly quantitative yields. Compounds are yellowish solids that are stable for a long time even in the presence of air. In contrast, only organobismuth(iii) compounds and could be successfully oxidized using SO2Cl2 to give compounds LBi(Ph)Cl3 () and LBiPh2Cl2 (). Compound is stable, but compound readily decomposed in solution and could not be isolated and stored for a longer period. All attempts to prepare compound LBiCl4 by the oxidation of with SO2Cl2 failed and resulted only in a mixture of products. All studied compounds were characterized by electrospray ionization (ESI) mass spectrometry, and (1)H and (13)C NMR spectroscopy. The molecular structures of , and were unambiguously established using single-crystal X-ray diffraction analysis. PMID:24121460

  18. Atomization of Bismuthane in a Dielectric Barrier Discharge: A Mechanistic Study.

    PubMed

    Kratzer, Jan; Zelina, Ondřej; Svoboda, Milan; Sturgeon, Ralph E; Mester, Zoltán; Dědina, Jiří

    2016-02-01

    Atomization of bismuthane in a planar dielectric barrier discharge (DBD) atomizer was investigated using a variety of probes, including atomic absorption spectrometry (AAS) to monitor distribution of free atoms along the optical path and direct analysis in real time (DART) coupled to an Orbitrap mass spectrometer to identify the structure of the species arising from the hydride generator as well as the atomizer. Results obtained with the DBD were compared to those from a conventional externally heated quartz tube atomizer (QTA). Free Bi atoms were essentially absent outside the central part of the DBD atomizer, suggesting their high reactivity. The gas phase analyte fraction transported beyond the confines of the DBD or QTA atomizers, quantified by inductively coupled plasma mass spectrometry (ICP-MS), was less than 10%. The amount of Bi found in acidic leachates of the interiors of both atomizers, representing the fraction retained on their surfaces, was ca. 90%. These complementary experiments comprising the determination of recovered Bi in the nitric acid leachates from deposition in the atomizer on the one hand and quantification of the Bi fraction transportable outside the atomizer on the other, were in excellent agreement, providing 100% mass balance of detected analyte. The high fraction of Bi deposited in the atomizers indicates significant reactivity of free Bi atoms, which is in accord with the fact that almost no free Bi atoms exist beyond the physical boundaries of the DBD. The extent of interference from other hydride forming elements (As, Sb, Se) on Bi response by AAS using DBD and QTA atomizers was investigated, with the former atomizer providing superior performance. Compared to QTA, DBD provided 2 orders of magnitude and 1 order of magnitude, respectively, better resistance to interference from Se and Sb. PMID:26796626

  19. Phonon coupling effects in magnetic moments of magic and semimagic nuclei

    NASA Astrophysics Data System (ADS)

    Saperstein, E. E.; Achakovskiy, O. I.; Kamerdzhiev, S. P.; Krewald, S.; Speth, J.; Tolokonnikov, S. V.

    2014-08-01

    Phonon coupling (PC) corrections to magnetic moments of odd neighbors of magic and semimagic nuclei are analyzed within the self-consistent Theory of Finite Fermi Systems (TFFS) based on the Energy Density Functional by S. A. Fayans et al. The perturbation theory in g {/L 2} is used where g L is the phonon-particle coupling vertex. A model is developed with separating non-regular PC contributions, the rest is supposed to be regular and included into the standard TFFS parameters. An ansatz is proposed to take into account the so-called tadpole term which ensures the total angular momentum conservation with g {/L 2} accuracy. An approximate method is suggested to take into account higher-order terms in g {/L 2}. Calculations are carried out for four odd-proton chains, the odd Tl, Bi, In, and Sb ones. Different PC corrections strongly cancel each other. In the result, the total PC correction to the magnetic moment in magic nuclei is, as a rule, negligible. In non-magic nuclei considered it is noticeable and, with only one exception, negative. On average it is of the order of -(0.1-0.5) µ N and improves the agreement of the theory with the data. Simultaneously we calculated the gyromagnetic ratios g {/L ph} of all low-lying phonons in 208Pb. For the 3{1/-} state it is rather close to the Bohr-Mottelson model prediction whereas for other L phonons, two 5- and six positive parity states, the difference from the Bohr-Mottelson values is significant.

  20. Breakthrough of 225Ac and its radionuclide daughters from an 225Ac/213Bi generator: development of new methods, quantitative characterization, and implications for clinical use.

    PubMed

    Ma, D; McDevitt, M R; Finn, R D; Scheinberg, D A

    2001-11-01

    Bisumth-213, a short-lived alpha particle emitting radionuclide, is generated from the decay of 225Ac, which has a half-life of 10 days. The development of a clinical 225Ac/213Bi generator and the preparation of a 213Bi radiolabeled antibody for radioimmunotherapy of leukemia have been reported. The 225Ac decay scheme is complex; therefore a thorough understanding of the impact of both the parent 225Ac and its daughters on radiolabeling, purification, and quantification is necessary for optimal use of the generator system. This paper reports: (i) unique new methods to measure 221Fr, 213Bi, and 209Pb, the prominent daughters of 225Ac; and (ii) a quantitative evaluation of 225Ac/213Bi generator breakthrough and the radionuclidic purity of 213Bi labeled radiopharmaceutical dose formulations. A quantitative multi-dimensional proportional scanning method was employed to distinguish and measure specific daughter radionuclides. This method combines thin layer chromatography in two perpendicular directions with attenuated collimation as a function of time for data collection and analysis. Francium-221 and 213Bi eluted differentially from the generator, and 221Fr contributed minimally to unchelated 213Bi in the reaction and final products. Lead-209 was present in the reaction solution, but not strongly bound by the chelating moiety either (i) under the 213Bi labeling reaction conditions or (ii) following chelated 213Bi decay. As a consequence of incorporating several new procedures to the operation of the generator, 225Ac breakthrough in the final product was further reduced and represented a trivial contaminant in the final drug formulations. PMID:11573800

  1. Nuclear Data Sheets for A = 199

    SciTech Connect

    Singh, Balraj

    2007-01-15

    Nuclear spectroscopic information for known nuclides of mass number 199 (Os,Ir,Pt,Au,Hg,Tl,Pb,Bi,Po,At,Rn,Fr) with Z = 76 to 87 and N = 123 to 112 have been evaluated and presented together with adopted energies and J{pi} of levels in these nuclei. No excited state data are available for {sup 199}Os and {sup 199}Fr, and very little information is available for levels in {sup 199}Ir, {sup 199}Rn and {sup 199}At. The decay of {sup 199}Ir to {sup 199}Pt has not been studied. The decay of the 90-min activity of {sup 199}Pb to {sup 199}Tl is known in detail but remains unpublished in the open literature, while the decay of the 12.2-min isomer remains mostly unknown. The decays of the two activities of {sup 199}Tl to {sup 199}Pb are not known as separate decay scheme for each of the activities, thus only a composite decay scheme is presented. Similar is the case for the decay of the two activities of {sup 199}Po to {sup 199}Bi. In ({sup 3}He,d) and ({alpha},t) studies for {sup 199}Au, disagreements are found between two independent contemporary studies. The most detailed structure known is for {sup 199}Pb with five magnetic-rotational (MR) dipole bands together with many other dipole bands which are of probable multi-quasiparticle nature. This work supersedes previous evaluations of A = 199 published in update mode by 1994Ar13; as full A-chain updates by 1988Sc02, 1978Ha12 and 1971Le37; and a mid-stream update of {sup 199}Pb nuclide by 2001Si44.

  2. Targeted T cell Therapy in Stage IV Breast Cancer: A Phase I Clinical Trial

    PubMed Central

    Lum, Lawrence G.; Thakur, Archana; Al-Kadhimi, Zaid; Colvin, Gerald A.; Cummings, Francis J.; Legare, Robert D.; Dizon, Don S.; Kouttab, Nicola; Maizel, Abby; Colaiace, William; Liu, Qin; Rathore, Ritesh

    2015-01-01

    PURPOSE This study reports a phase I immunotherapy (IT) trial in 23 women with metastatic breast cancer consisting of eight infusions of anti-CD3 × anti-HER2 bispecific antibody (HER2Bi) armed anti-CD3 activated T cells (ATC) in combination with low dose interleukin 2 (IL-2) and granulocyte-macrophage-colony stimulating factor to determine safety, maximum tolerated dose (MTD), technical feasibility, T cell trafficking, immune responses, time to progression, and overall survival (OS). EXPERIMENTAL DESIGN ATC were expanded from leukapheresis product using IL-2 and anti-CD3 monoclonal antibody and armed with HER2Bi. In 3+3 dose escalation design, groups of 3 patients received 5, 10, 20, or 40 × 109 armed ATC (aATC) per infusion. RESULTS There were no dose limiting toxicities and the MTD was not defined. It was technically feasible to grow 160 × 109 ATC from a single leukapheresis. aATC persisted in the blood for weeks and trafficked to tumors. Infusions of aATC induced anti-breast cancer responses and increases in immunokines. At 14.5 weeks after enrollment, 13 of 22 (59.1%) evaluable patients had stable disease and 9 of 22 (40.9%) had progressive disease. The median OS was 36.2 months for all patients, 57.4 months for HER2 3+ patients, and 27.4 months for HER2 0–2+ patients. CONCLUSIONS Targeting HER2 positive and negative tumors with aATC infusions induced anti-tumor responses, increases in Th1 cytokines and IL-12 serum levels that suggest that aATC infusions vaccinated patients against their own tumors. These results provide a strong rationale for conducting phase II trials. PMID:25688159

  3. The Role of Siglec-1 and SR-BI Interaction in the Phagocytosis of Oxidized Low Density Lipoprotein by Macrophages

    PubMed Central

    Li, Chang; Zhu, Lin; Wu, Li-juan; Zhong, Ren-qian

    2013-01-01

    Background Macrophages play a proatherosclerotic role in atherosclerosis via oxLDL uptake. As an adhesion molecular of I-type lectins, Siglec-1 is highly expressed on circulating monocytes and plaque macrophages of atherosclerotic patients, but the exact role of Siglec-1 has not been elucidated. Methods In this study, oxLDL was used to stimulate Siglec-1 and some oxLDL receptors (SR-BI, CD64, CD32B, LOX-1 and TLR-4) expression on bone marrow-derived macrophages, whereas small interfering RNA was used to down-regulate Siglec-1. Meanwhile, an ELISA-based assay for Siglec-1-oxLDL interaction was performed, and co-immunoprecipitation (co-IP) and laser scanning confocal microscopy (LSCM) were used to determine the role of Siglec-1 in oxLDL uptake by macrophages. Results We found that oxLDL could up-regulate the expression of various potential oxLDL receptors, including Siglec-1, in a dose-dependent manner. Moreover, down-regulation of Siglec-1 could attenuate oxLDL uptake by Oil red O staining. LSCM revealed that Siglec-1 and CD64/SR-BI may colocalize on oxLDL-stimulated macrophage surface, whereas co-IP showed that Siglec-1 and SR-BI can be immunoprecipitated by each other. However, no direct interaction between Siglec-1 and oxLDL was found in the in vitro protein interaction system. Conclusions Thus, Siglec-1 can interact with SR-BI in the phagocytosis of oxLDL by macrophages, rather than act as an independent receptor for oxLDL. PMID:23520536

  4. DTPA complexation of bismuth in human blood serum.

    PubMed

    Montavon, G; Le Du, A; Champion, J; Rabung, T; Morgenstern, A

    2012-07-28

    The in vivo(212)Pb/(212)Bi generator is promising for application in targeted alpha therapy (TAT) of cancer. One main limitation of its therapeutic application is due to potential release of (212)Bi from the radioconjugate upon radioactive decay of the mother nuclide (212)Pb, potentially leading to irradiation of healthy tissue. The objective of the present work is to assess whether the chelate CHX-A''-DTPA (N-(2-aminoethyl)-trans-1,2-diaminocyclohexane-N,N',N''-pentaacetic acid) bound to a biological carrier molecule may be able to re-complex released (212)Bi under in vivo conditions to limit its translocation from the target site. CHX-A''-DTPA was bound to bovine gamma globulin (BGG) to mimic a model conjugate and the stability of the Bi-CHX-A''-DTPA-BGG conjugate was studied in blood serum by ultrafiltration. TRLFS experiments using Cm(III) as a fluorescent probe demonstrated that linking CHX-A''-DTPA to BGG does not affect the coordination properties of the ligand. Furthermore, comparable stability constants were observed between Bi(III) and free CHX-A''-DTPA, BGG-bound CHX-A''-DTPA and DTPA. The complexation constants determined between Bi(III) and the chelate molecules are sufficiently high to allow ultra trace amounts of the ligand to efficiently compete with serum transferrin controlling Bi(III) speciation in blood plasma conditions. Nevertheless, CHX-A''-DTPA is not able to complex Bi(III) generated in blood serum because of the strong competition between Bi(III) and Fe(II) for the ligand. In other words, CHX-A''-DTPA is not "selective" enough to limit Bi(iii) release in the body when applying the (212)Pb/(212)Bi in vivo generator. PMID:22678751

  5. Converting an AEG Cyclotron to H{sup -} Acceleration and Extraction

    SciTech Connect

    Ramsey, Fred; Carroll, Lewis; Rathmann, Tom; Huenges, Ernst; Bechtold, Matthias Mentler Volker

    2009-03-10

    Clinical Trials are under way to evaluate agents labeled with the nuclide {sup 225}Ac and its decay product {sup 213}Bi, in targeted alpha-immuno-therapy. {sup 225}Ac can be produced on a medium-energy cyclotron via the nuclear reaction {sup 226}Ra(p,n){sup 225}Ac. To demonstrate proof-of-principle, a vintage AEG cyclotron, Model E33, with an internal target, had been employed in a pilot production program at the Technical University of Munich (TUM). To enhance production capability and further support the clinical studies, the TUM facility has recently been refurbished and upgraded, adding a new external beam-line, automated target irradiation and transport systems, new laboratories, hot cells, etc.. An improved high-power rotating target has been built and installed. The AEG cyclotron itself has also been modified and upgraded to accelerate and extract H{sup -} ions. We have designed, built, and tested a new axial Penning-type ion source which is optimized for the production of H{sup -} ions. The ion source has continued to evolve through experiment and experience. Steady improvements in materials and mechanics have led to enhanced source stability, life-time, and H{sup -} production. We have also designed and built a precision H{sup -} charge-exchange beam-extraction system which is equipped with a vacuum lock. To fit within the tight mechanical constraint imposed by the narrow magnet gap, the system incorporates a novel chain-drive foil holder and foil-changer mechanism. The reconfigured cyclotron system has now been in operation for more than 1 year. Three long-duration target irradiations have been conducted. The most recent bombardment ran 160 continuous hours at a beam on target of {approx}80 microamperes for a total yield of {approx}70 milli-curies of {sup 225}Ac.

  6. Radioimmunotherapy of breast cancer metastases with alpha-particle emitter 225Ac: comparing efficacy with 213Bi and 90Y.

    PubMed

    Song, Hong; Hobbs, Robert F; Vajravelu, Ravy; Huso, David L; Esaias, Caroline; Apostolidis, Christos; Morgenstern, Alfred; Sgouros, George

    2009-12-01

    alpha-Particles are suitable to treat cancer micrometastases because of their short range and very high linear energy transfer. alpha-Particle emitter (213)Bi-based radioimmunotherapy has shown efficacy in a variety of metastatic animal cancer models, such as breast, ovarian, and prostate cancers. Its clinical implementation, however, is challenging due to the limited supply of (225)Ac, high technical requirement to prepare radioimmunoconjugate with very short half-life (T(1/2) = 45.6 min) on site, and prohibitive cost. In this study, we investigated the efficacy of the alpha-particle emitter (225)Ac, parent of (213)Bi, in a mouse model of breast cancer metastases. A single administration of (225)Ac (400 nCi)-labeled anti-rat HER-2/neu monoclonal antibody (7.16.4) completely eradicated breast cancer lung micrometastases in approximately 67% of HER-2/neu transgenic mice and led to long-term survival of these mice for up to 1 year. Treatment with (225)Ac-7.16.4 is significantly more effective than (213)Bi-7.16.4 (120 microCi; median survival, 61 days; P = 0.001) and (90)Y-7.16.4 (120 microCi; median survival, 50 days; P < 0.001) as well as untreated control (median survival, 41 days; P < 0.0001). Dosimetric analysis showed that (225)Ac-treated metastases received a total dose of 9.6 Gy, significantly higher than 2.0 Gy from (213)Bi and 2.4 Gy from (90)Y. Biodistribution studies revealed that (225)Ac daughters, (221)Fr and (213)Bi, accumulated in kidneys and probably contributed to the long-term renal toxicity observed in surviving mice. These data suggest (225)Ac-labeled anti-HER-2/neu monoclonal antibody could significantly prolong survival in HER-2/neu-positive metastatic breast cancer patients. PMID:19920193

  7. A radiometric and petrographic approach to risk assessment at Alte Madonie Mounts region (Sicily, Italy).

    PubMed

    Lanzo, G; Rizzo, S; Tomarchio, E

    2014-03-01

    The main goal of this work was to assess the radiological hazard at Alte Madonie Mounts region (north-central Sicily, Italy) in response to rumours of an increase in the incidence of cancer in this area. A correlation between the natural radionuclide contents and the petrographic features of the soil and rock samples was also evaluated. A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in 'Marinelli' beakers for 20 d prior to measurement to ensure that a radioactive equilibrium between (226)Ra and (214)Bi had been reached. A gamma-ray spectrometer was used to quantify the radioactivity concentrations. To determine (238)U and (232)Th activities, the 609.3-keV line from (214)Bi in secular equilibrium with (226)Ra and the 911-keV line from (228)Ac, with which (232)Th can be assumed to be in equilibrium, were used, respectively. The gamma transition of 1461 keV was used to determine (40)K activity. The average values of the concentrations of (214)Bi, (228)Ac and (40)K were 30, 17 and 227 Bq kg(-1), respectively, whereas the greatest values were 134, 59 and 748 Bq kg(-1), respectively. A linear relationship was found between the activity values of (214)Bi, (228)Ac and (40)K. An exception was found for a group of samples in which the (214)Bi activities were much higher than expected. The chemical compositions and mineralogical features of the samples permitted the justification of these anomalies. The results of the primordial radionuclide contents are reassuring from a radiation protection point of view because the activities of the uranium and thorium series products and of the (40)K do not present a significant radiological hazard. PMID:24106332

  8. Ultrafast resonance energy transfer in the umbelliferone-alizarin bichromophore.

    PubMed

    Lapini, Andrea; Fabbrizzi, Pierangelo; Piccardo, Matteo; di Donato, Mariangela; Lascialfari, Luisa; Foggi, Paolo; Cicchi, Stefano; Biczysko, Malgorzata; Carnimeo, Ivan; Santoro, Fabrizio; Cappelli, Chiara; Righini, Roberto

    2014-06-01

    In this work we present the synthesis, time-resolved spectroscopic characterization and computational analysis of a bichromophore composed of two very well-known naturally occurring dyes: 7-hydroxycoumarin (umbelliferone) and 1,2-dihydroxyanthraquinone (alizarin). The umbelliferone donor (Dn) and alizarin acceptor (Ac) moieties are linked to a triazole ring viaσ bonds, providing a flexible structure. By measuring the fluorescence quantum yields and the ultrafast transient absorption spectra we demonstrate the high efficiency (∼85%) and the fast nature (∼1.5 ps) of the energy transfer in this compound. Quantum chemical calculations, within the density functional theory (DFT) approach, are used to characterize the electronic structure of the bichromophore (Bi) in the ground and excited states. We simulate the absorption and fluorescence spectra using the TD-DFT methods and the vertical gradient approach (VG), and include the solvent effects by adopting the conductor-like polarizable continuum model (CPCM). The calculated electronic structure suggests the occurrence of weak interactions between the electron densities of Dn and Ac in the excited state, indicating that the Förster-type transfer is the appropriate model for describing the energy transfer in this system. The average distance between Dn and Ac moieties calculated from the conformational analysis (12 Å) is in very good agreement with the value estimated from the Förster equation (∼11 Å). At the same time, the calculated rate constant for energy transfer, averaged over multiple conformations of the system (3.6 ps), is in reasonable agreement with the experimental value (1.6 ps) estimated by transient absorption spectroscopy. The agreement between experimental results and computational data leads us to conclude that the energy transfer in Bi is well described by the Förster mechanism. PMID:24513677

  9. Slowly fading super-luminous supernovae that are not pair-instability explosions

    NASA Astrophysics Data System (ADS)

    Nicholl, M.; Smartt, S. J.; Jerkstrand, A.; Inserra, C.; McCrum, M.; Kotak, R.; Fraser, M.; Wright, D.; Chen, T.-W.; Smith, K.; Young, D. R.; Sim, S. A.; Valenti, S.; Howell, D. A.; Bresolin, F.; Kudritzki, R. P.; Tonry, J. L.; Huber, M. E.; Rest, A.; Pastorello, A.; Tomasella, L.; Cappellaro, E.; Benetti, S.; Mattila, S.; Kankare, E.; Kangas, T.; Leloudas, G.; Sollerman, J.; Taddia, F.; Berger, E.; Chornock, R.; Narayan, G.; Stubbs, C. W.; Foley, R. J.; Lunnan, R.; Soderberg, A.; Sanders, N.; Milisavljevic, D.; Margutti, R.; Kirshner, R. P.; Elias-Rosa, N.; Morales-Garoffolo, A.; Taubenberger, S.; Botticella, M. T.; Gezari, S.; Urata, Y.; Rodney, S.; Riess, A. G.; Scolnic, D.; Wood-Vasey, W. M.; Burgett, W. S.; Chambers, K.; Flewelling, H. A.; Magnier, E. A.; Kaiser, N.; Metcalfe, N.; Morgan, J.; Price, P. A.; Sweeney, W.; Waters, C.

    2013-10-01

    Super-luminous supernovae that radiate more than 1044 ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of `pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of 56Ni are synthesized; this isotope decays to 56Fe via 56Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10-6 times that of the core-collapse rate.

  10. Lactate-An Integrative Mirror of Cancer Metabolism.

    PubMed

    Walenta, Stefan; Voelxen, Nadine F; Mueller-Klieser, Wolfgang

    2016-01-01

    The technique of induced metabolic bioluminescence imaging (imBI) has been developed to obtain a "snapshot" of the momentary metabolic status of biological tissues. Using cryosections of snap-frozen tissue specimens, imBI combines highly specific and sensitive in situ detection of metabolites with a spatial resolution on a microscopic level and with metabolic imaging in relation to tissue histology. Here, we present the application of imBI in human colorectal cancer. Comparing the metabolic information of one biopsy with that of 2 or 3 biopsies per individual cancer, the classification into high versus low lactate tumors, reflecting different glycolytic activities, based on a single biopsy was in agreement with the result from multiple biopsies in 83 % of all cases. We further demonstrate that the metabolic status of tumor tissue can be preserved at least over 10 years by storage in liquid nitrogen, but not by storage at -80 °C. This means that tissue banking with long-term preservation of the metabolic status is possible at -180 °C, which may be relevant for studies on long-term survival of cancer patients. As with other tumor entities, tissue lactate concentration was shown to be correlated with tumor development and progression in colorectal cancer. At first-time diagnosis, lactate values were low in rectal normal tissue and adenomas, were significantly elevated to intermediate levels in non-metastatic adenocarcinomas, and were very high in carcinomas with distant metastasis. There was an inverse behavior of tissue glucose concentration under corresponding conditions. The expression level of monocarboxylate transporter-4 (MCT4) was positively correlated with the tumor lactate concentration and may thus contribute to high lactate tumors being associated with a high degree of malignancy. PMID:27557533

  11. Association between resting-state brain functional connectivity and muscle sympathetic burst incidence.

    PubMed

    Taylor, Keri S; Kucyi, Aaron; Millar, Philip J; Murai, Hisayoshi; Kimmerly, Derek S; Morris, Beverley L; Bradley, T Douglas; Floras, John S

    2016-02-01

    The insula (IC) and cingulate are key components of the central autonomic network and central nodes of the salience network (SN), a set of spatially distinct but temporally correlated brain regions identified with resting-state (task free) functional MRI (rsMRI). To examine the SN's involvement in sympathetic outflow, we tested the hypothesis that individual differences in intrinsic connectivity of the SN correlate positively with resting postganglionic muscle sympathetic nerve activity (MSNA) burst incidence (BI) in subjects without and with obstructive sleep apnea (OSA). Overnight polysomnography, 5-min rsMRI, and fibular MSNA recording were performed in 36 subjects (mean age 57 yr; 10 women, 26 men). Independent component analysis (ICA) of the entire cohort identified the SN as including bilateral IC, pregenual anterior cingulate cortex (pgACC), midcingulate cortex (MCC), and the temporoparietal junction (TPJ). There was a positive correlation between BI and the apnea-hypopnea index (AHI) (P < 0.001), but dual-regression analysis identified no differences in SN functional connectivity between subjects with no or mild OSA (n = 17) and moderate or severe (n = 19) OSA. Correlation analysis relating BI to the strength of connectivity within the SN revealed large (i.e., spatial extent) and strong correlations for the left IC (P < 0.001), right pgACC/MCC (P < 0.006), left TPJ (P < 0.004), thalamus (P < 0.035), and cerebellum (P < 0.013). Indexes of sleep apnea were unrelated to BI and the strength of SN connectivity. There were no relationships between BI and default or sensorimotor network connectivity. This study links connectivity within the SN to MSNA, demonstrating several of its nodes to be key sympathoexcitatory regions. PMID:26538607

  12. Effect of composition and heat treatment on MnBi magnetic materials

    SciTech Connect

    Cui, Jun; Choi, Jung-Pyung; Polikarpov, Evgueni; Bowden, Mark E; Xie, Wei; Li, Guosheng; Nie, Zimin; Zarkevich, Nikolai; Kramer, Matthew J; Johnson, Duane

    2014-10-01

    The metallic compound MnBi is a promising rare-earth-free permanent magnet material, unique among all candidates for its high intrinsic coercivity (Hci) and its large positive temperature coefficient. The Hci of MnBi in thin-film or powder form can exceed 12 and 26 kOe at 300 and 523 K, respectively. Such a steep rise in Hci with increasing temperature is unique to MnBi. Consequently, MnBi is a highly sought-after hard phase for exchange coupling nanocomposite magnets. However, the reaction between Mn and Bi is peritectic, and hence Mn tends to precipitate out of the MnBi liquid during the solidification process. As result, when the alloy is prepared using conventional induction or arc-melting casting methods, additional Mn is required to compensate the precipitation of Mn. In addition to composition, post-casting annealing plays an important role in obtaining a high content of MnBi low-temperature phase (LTP) because the annealing encourages the Mn precipitates and the unreacted Bi to react, forming the desired LTP phase. Here we report a systematic study of the effect of composition and heat treatments on the phase content and magnetic properties of Mn–Bi alloys. In this study, 14 compositions were prepared using conventional metallurgical methods, and the compositions, crystal structures, phase content and magnetic properties of the resulting alloys were analyzed. The results show that the composition with 55 at.% Mn exhibits both the highest LTP content (93 wt.%) and magnetization (74 emu g-1 with 9 T applied field at 300 K).

  13. Assessment of the relationship between entomologic indicators of Aedes aegypti and the epidemic occurrence of dengue virus 3 in a susceptible population, São José do Rio Preto, São Paulo, Brazil.

    PubMed

    Chiaravalloti-Neto, Francisco; Pereira, Mariza; Fávaro, Eliane Aparecida; Dibo, Margareth Regina; Mondini, Adriano; Rodrigues-Junior, Antonio Luiz; Chierotti, Ana Patrícia; Nogueira, Maurício Lacerda

    2015-02-01

    The aims of this study were to describe the occurrence of dengue in space and time and to assess the relationships between dengue incidence and entomologic indicators. We selected the dengue autochthonous cases that occurred between September 2005 and August 2007 in São José do Rio Preto to calculate incidence rates by month, year and census tracts. The monthly incidence rates of the city were compared to the monthly Breteau indices (BI) of the São José do Rio Region. Between December 2006 and February 2007, an entomological survey was conducted to collect immature forms of Aedes aegypti in Jaguaré, a São José do Rio Preto neighborhood, and to obtain entomological indices. These indices were represented using statistical interpolation. To represent the occurrence of dengue in the Jaguaré neighborhood in 2006 and 2007, we used the Kernel ratio and to evaluate the relationship between dengue and the entomological indices, we used a generalized additive model in a spatial case-control design. Between September 2005 and August 2007, the occurrence of dengue in São José do Rio Preto was almost entirely caused by DENV3, and the monthly incidence rates presented high correlation coefficients with the monthly BI. In Jaguaré neighborhood, the entomological indices calculated by hectare were better predictors of the spatial distribution of dengue than the indices calculated by properties, but the pupae quantification did not show better prediction qualities than the indices based on the container positivity, in relation to the risk of dengue occurrence. The fact that the municipality's population had a high susceptibility to the serotype DENV3 before the development of this research, along with the almost total predominance of the occurrence of this serotype between 2005 and 2007, facilitated the analysis of the epidemiological situation of the disease and allowed us to connect it to the entomological indicators. PMID:25484110

  14. Behavioral inhibition in childhood predicts smaller hippocampal volume in adolescent offspring of parents with panic disorder.

    PubMed

    Schwartz, C E; Kunwar, P S; Hirshfeld-Becker, D R; Henin, A; Vangel, M G; Rauch, S L; Biederman, J; Rosenbaum, J F

    2015-01-01

    Behavioral inhibition (BI) is a genetically influenced behavioral profile seen in 15-20% of 2-year-old children. Children with BI are timid with people, objects and situations that are novel or unfamiliar, and are more reactive physiologically to these challenges as evidenced by higher heart rate, pupillary dilation, vocal cord tension and higher levels of cortisol. BI predisposes to the later development of anxiety, depression and substance abuse. Reduced hippocampal volumes have been observed in anxiety disorders, depression and posttraumatic stress disorder. Animal models have demonstrated that chronic stress can damage the hippocampal formation and implicated cortisol in these effects. We, therefore, hypothesized that the hippocampi of late adolescents who had been behaviorally inhibited as children would be smaller compared with those who had not been inhibited. Hippocampal volume was measured with high-resolution structural magnetic resonance imaging in 43 females and 40 males at 17 years of age who were determined to be BI+ or BI- based on behaviors observed in the laboratory as young children. BI in childhood predicted reduced hippocampal volumes in the adolescents who were offspring of parents with panic disorder, or panic disorder with comorbid major depression. We discuss genetic and environmental factors emanating from both child and parent that may explain these findings. To the best of our knowledge, this is the first study to demonstrate a relationship between the most extensively studied form of temperamentally based human trait anxiety, BI, and hippocampal structure. The reduction in hippocampal volume, as reported by us, suggests a role for the hippocampus in human trait anxiety and anxiety disorder that warrants further investigation. PMID:26196438

  15. Concentrations of radionuclides in fish collected from Bikini Atoll between 1977 and 1984

    SciTech Connect

    Noshkin, V.E.; Wong, K.M.; Eagle, R.J.; Jokela, T.A.; Brunk, J.A.

    1986-07-01

    This report summarizes all available data on the concentrations of radionuclides in fish from Bikini Atoll between 1977 and 1984. As found in other global studies, /sup 137/Cs is most highly accumulated in edible flesh of all species of fish, the lowest fractions are found in the bone or liver. The mean concentration of /sup 137/Cs in muscle of reef fish from the southern part of the atoll is comparable to the global fallout concentration measured in market samples of fish collected from Chicago, Illinois, in 1982. /sup 90/Sr is generally associated with non-edible parts of fish, such as bone or viscera. Twenty-five to fifty percent of the total body burden of /sup 60/Co is accumulated in the muscle tissue; the remainder is distributed among the liver, skin, and viscera. The mean concentration of /sup 60/Co in fish has been decreasing at a rate faster than radiological decay alone. Most striking is the range of /sup 207/Bi concentrations among different species of fish collected at the same time and place. Highest concentrations of /sup 207/Bi were consistently detected in the muscle (and other tissues) of goatfish and some of the pelagic lagoon fish. In other reef fish, such as mullet, surgeonfish, and parrotfish, /sup 207/Bi was usually below detection limits by gamma spectrometry. Over 70% of the whole-body activity of /sup 207/Bi in goatfish is associated with the muscle tissue, whereas less than 5% is found in the muscle of mullet and surgeonfish. Neither /sup 239 +240/Pu nor /sup 241/Am is significantly accumulated in the muscle tissue of any species of fish. Apparently, /sup 238/Pu is in a more readily available form for accumulation by fishes than /sup 239 +240/Pu. Based on a daily ingestion rate of 200 q of fish flesh, dose rates to individuals through the fish-food ingestion pathway are well below current Federal guidelines.

  16. CANABIC: CANnabis and Adolescents: effect of a Brief Intervention on their Consumption – study protocol for a randomized controlled trial

    PubMed Central

    2014-01-01

    Background Cannabis is the most consumed illegal substance in France. General practitioners (GPs) are the health professionals who are most consulted by adolescents. Brief intervention (BI) is a promising care initiative for the consumption of cannabis, and could be a tool for GPs in caring for adolescents who consume cannabis. The aim of the CANABIC study is to measure the impact of a BI carried out by a GP on the consumption of cannabis by adolescents of 15 to 25 years of age. Methods A randomized clustered controlled trial, stratified over three areas (Auvergne, Languedoc-Roussillon, and Rhône - Alpes), comparing an intervention group, which carries out the BI in consultation, and a control group, which ensures routine medical care. The main assessment criterion is the consumption of cannabis by amount of joints per month, at 12 months. The amount necessary to highlight a significant difference between the two groups of 30% of consumption at 12 months is 250 patients (50 GPs, 5 patients per GP; risk α = 5%; power = 90%; intra-cluster correlation coefficient ρ = 0.2; Hawthorne effect = 15%; lost to follow-up rates for GPs = 10% and for patients = 20%). This plan is replicated for the three areas, and therefore a total of 750 patients are expected. The secondary criteria for judgment are the associated consumption of tobacco and alcohol, the perception of the consequences of consumption, and the driving of a vehicle following consumption. Discussion Research about BI for young cannabis users is underway. The aim of the CANABIC study is to validate a BI suited to adolescents who consume cannabis, which may be performed in the general practice. This would provide a tool for their treatment by a GP, which could be widely distributed during initial or further medical training. Trial registration CANABIC is a randomized clustered trial (NCT01433692, registered 2011 Sept 12), PHRC funded: Clinical Research Hospital Program (Governmental

  17. Adaptations to chronic rapamycin in mice

    PubMed Central

    Dodds, Sherry G.; Livi, Carolina B.; Parihar, Manish; Hsu, Hang-Kai; Benavides, Adriana D.; Morris, Jay; Javors, Martin; Strong, Randy; Christy, Barbara; Hasty, Paul; Sharp, Zelton Dave

    2016-01-01

    Rapamycin inhibits mechanistic (or mammalian) target of rapamycin (mTOR) that promotes protein production in cells by facilitating ribosome biogenesis (RiBi) and eIF4E-mediated 5'cap mRNA translation. Chronic treatment with encapsulated rapamycin (eRapa) extended health and life span for wild-type and cancer-prone mice. Yet, the long-term consequences of chronic eRapa treatment are not known at the organ level. Here, we report our observations of chronic eRapa treatment on mTORC1 signaling and RiBi in mouse colon and visceral adipose. As expected, chronic eRapa treatment decreased detection of phosphorylated mTORC1/S6K substrate, ribosomal protein (rpS6) in colon and fat. However, in colon, contrary to expectations, there was an upregulation of 18S rRNA and some ribosomal protein genes (RPGs) suggesting increased RiBi. Among RPGs, eRapa increases rpl22l1 mRNA but not its paralog rpl22. Furthermore, there was an increase in the cap-binding protein, eIF4E relative to its repressor 4E-BP1 suggesting increased translation. By comparison, in fat, there was a decrease in the level of 18S rRNA (opposite to colon), while overall mRNAs encoding ribosomal protein genes appeared to increase, including rpl22, but not rpl22l1 (opposite to colon). In fat, there was a decrease in eIF4E relative to actin (opposite to colon) but also an increase in the eIF4E/4E-BP1 ratio likely due to reductions in 4E-BP1 at our lower eRapa dose (similar to colon). Thus, in contrast to predictions of decreased protein production seen in cell-based studies, we provide evidence that colon from chronically treated mice exhibited an adaptive ‘pseudo-anabolic’ state, which is only partially present in fat, which might relate to differing tissue levels of rapamycin, cell-type-specific responses, and/or strain differences. PMID:27237224

  18. Correlation of Clinico-pathological Classification of Hansen's Disease in a South Indian City.

    PubMed

    Lobo, A C; Pai, R R; Gautam, K; Kuruvila, M

    2014-01-01

    Hansen's Disease (HD) presents itself in different forms depending on the individual's immune status, and based on this Ridley-Jopling classified the disease into five sub-groups. The aim of this study was to evaluate the role of histopathology and bacteriological index (BI) in accurate staging of HD with clinical correlation. Fifty HD patients with clinical diagnosis confirmed by histopathology were included. Patients in reaction and on treatment were excluded. Case records and histopathological slides were viewed and BI was recorded. In 10/50 cases, a diagnosis of HD was made or suspected, but were not clinically classified. In these, histopathology proved useful in diagnosis and classification. Indeterminate HD was the most common histopathological diagnosis (6 cases). The remaining 40 patients, were clinically classified using the Ridley-Jopling classification, as Indeterminate Leprosy (IL) in 10/40 (25%), Tuberculoid Leprosy (TT) 5/40 (12.5%), Borderline Tuberculoid (BT) 16/40 (40%), Borderline Lepromatous (BL) 4/40 (10%) and Lepromatous Leprosy (LL) 5 (12.5%). HD was common in males with male to female ratio of 1.66:1 and affected the younger individuals (maximum in 21 to 30 years). On histopathology BT was the most common type (40%) followed by IL (27.5%), BL (12.5%), TT (10%) and LL (10%). No case of Mid-Borderline (BB) type was diagnosed clinically or histopathologically. Overall concordance between clinical and histopathological diagnosis was 65% (26/40 cases) and for each type was IL = 80%, TT = 20%, BT = 75%, BL = 50% and LL = 60%. Where classification seemed difficult as in cases of BT and BL, II played an important role. The overall concordance between clinical classification and histopathological diagnosis of DO is 65% in this study. Th *discordance that is observed is between BT and TT, the paucibacillary type and BL andILL the multibacillary type and hence the treatment is not affected. Overall, IL was a common diagnosis on histopathology in this

  19. Novel Apo E-Derived ABCA1 Agonist Peptide (CS-6253) Promotes Reverse Cholesterol Transport and Induces Formation of preβ-1 HDL In Vitro

    PubMed Central

    Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; Genest, Jacques

    2015-01-01

    Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from the carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These mechanisms are

  20. Use of Microgravity to Control the Microstructure of Eutectics

    NASA Technical Reports Server (NTRS)

    Wilcox, William R.; Regel, Liya L.; Smith, Reginald W.

    1998-01-01

    This grant began in June of 1996. Its long term goal is to be able to control the microstructure of directionally solidified eutectic alloys, through an improved understanding of the influence of convection. The primary objective of the present projects is to test hypotheses for the reported influence of microgravity on the microstructure of three fibrous eutectics (MnBi-Bi, InSb-NiSb, Al3Ni-Al). A secondary objective is to determine the influence of convection on the microstructure of other eutectic alloys. Two doctoral students and a masters student supported as a teaching assistant were recruited for this research. Techniques were developed for directional solidification of MnBi-Bi eutectics with periodic application of current pulses to produce an oscillatory freezing rate. Image analysis techniques were developed to obtain the variation in MnBi fiber spacing, which was found to be normally distributed. The mean and standard deviation of fiber spacing were obtained for several freezing conditions. Eighteen ampoules were prepared for use in the gradient freeze furnace QUELD developed at Queen's University for use in microgravity. Nine of these ampoules will be solidified soon at Queen's in a ground-based model. We hope to solidify the other nine in the QUELD that is mounted on the Canadian Microgravity Isolation Mount on MIR. Techniques are being developed for directional solidification of the Al-Si eutectic at different freezing rates, with and without application of accelerated crucible rotation to induce convection. For the first time, theoretical methods are being developed to analyze eutectic solidification with an oscillatory freezing rate. In a classical sharp-interface model, we found that an oscillatory freezing rate increases the deviation of the average interfacial composition from the eutectic, and increases the undercooling of the two phases by different amounts. This would be expected to change the volume fraction solidifying and the fiber spacing

  1. Bi-melt formation and gold scavenging from hydrothermal fluids: An experimental study

    NASA Astrophysics Data System (ADS)

    Tooth, Blake; Ciobanu, Cristiana L.; Green, Leonard; O'Neill, Brian; Brugger, Joël

    2011-10-01

    The role of polymetallic melts in scavenging ore components has recently been highlighted in the context of fluid-poor metamorphosed ore deposits. In contrast, the role of polymetallic melts in systems dominated by hydrothermal fluids remains poorly understood. Using a simple Au-Bi model system, we explored experimentally whether such polymetallic melts can precipitate directly from a hydrothermal fluid, and investigated the ability of these melts to scavenge Au from the solution. The experiments were conducted in custom-built flow-through reactors, designed to reproduce a hydrothermal system where melt components are dissolved at one stage along the flow path (e.g., Bi was dissolved by placing Bi-minerals along the fluid path), whereas melt precipitation was caused further along the flow path by fluid-rock interaction. Bi-rich melts were readily obtained by reaction with pyrrhotite, graphite or amorphous FeS. When Au was added to the system, Bi-Au melts with compositions consistent with the Au-Bi phase diagram were obtained. In the case of fluid reaction with pyrrhotite, epitaxial replacement of pyrrhotite by magnetite was observed, with textures consistent with an interface-coupled dissolution-reprecipitation reaction (ICDRR). In this case, the metallic melt precipitated as blebs that were localized at the replacement front or within the porous magnetite. Direct fractionation of Bi-Au melts from a hydrothermal fluid, or precipitation of a Bi-melt followed by partitioning of Au from ambient fluid, offer new pathways to the enrichment of minor ore components such as Au, without requiring fluid saturation with respect to a Au mineral. This mechanism can explain the strong geochemical affinity recognized between Au and low-melting point chalcophile elements such as Bi in many gold deposits. Examples of deposits where such a model may be applicable include orogenic gold deposits and gold skarns. Contrary to models involving migration of polymetallic melts to explain

  2. In vitro and in vivo evaluation of novel ligands for radioimmunotherapy.

    PubMed

    Chong, Hyun-Soon; Milenic, Diane E; Garmestani, Kayhan; Brady, Erik D; Arora, Hans; Pfiester, Candice; Brechbiel, Martin W

    2006-05-01

    Novel ligands cis-2,6-bis[N,N-bis(carboxymethyl)aminomethyl]-1-piperidineacetic acid (PIP-DTPA), cis-[(1R,11S)-6,9,15-Tris-carboxymethyl-3,6,9,15-tetraazabicyclo[9.3.1]pentadec-3-yl]-acetic acid (PIP-DOTA), cis-{2,7-bis-[bis-carboxymethyl-amino)-methyl]-azepan-1-yl}-acetic acid (AZEP-DTPA), [2-(4,7-bis-carboxymethyl-[1,4,7]triazacyclononan-1-yl-ethyl]-2-carbonylmethyl-amino]-tetraacetic acid (NETA) and [{4-carboxymethyl-7-[2-(carboxymethylamino)-ethyl]-perhydro-1,4,7-triazonin-1-yl}-acetic acid (NPTA) are investigated as potential chelators of 177Lu, 90Y, 212Pb and 213Bi for radioimmunotherapy (RIT). The new ligands are radiolabeled with 177Lu, 86/88/90Y, 203Pb and 205/6Bi, and in vitro stability and in vivo stability of the radiolabeled complexes are assessed in human serum and athymic mice, respectively. In vitro studies indicate that all radiolabeled complexes with the exception of 90Y-AZEP-DTPA are stable in serum for 5-11 days. All new ligands examined herein are found to tightly hold 177Lu in vivo. Piperidine-backboned DTPA (PIP-DTPA) complexes radiolabeled with all radioisotopes examined display excellent in vivo stability, that is, excretion without dissociation. The azepane-backboned DTPA derivative, AZEP-DTPA, appears ineffective in binding all but 177Lu in vivo. NETA and NPTA radiolabeled with 86Y or 177Lu exhibit rapid blood clearance and low organ uptakes. Significant accretion in the kidney, femur and/or liver is observed with 203Pb-labeled AZEP-DTPA, PIP-DOTA and NPTA. Both 203Pb-PIP-DOTA and 205/6Bi-PIP-DOTA result in moderate to high renal accumulation of radioactivity. NETA exhibits improved renal accumulation with respect to PIP-DOTA for 205/6Bi but also shows significant liver uptake. Of all ligands studied, only PIP-DTPA appears to effectively bind 203Pb and 205/6Bi in vivo. PIP-DTPA, PIP-DOTA, NETA and NPTA all show strong evidence of rapid blood clearance and low organ uptake for 177Lu and 90Y. Serum stability and in vivo biodistribution

  3. Ab initio study of the strain dependent thermodynamics of Bi doping in GaAs

    NASA Astrophysics Data System (ADS)

    Jacobsen, Heather; Puchala, Brian; Kuech, Thomas F.; Morgan, Dane

    2012-08-01

    The thermodynamics of Bi incorporation into bulk and epitaxial GaAs was studied using density functional theory (DFT) and anharmonic elasticity calculations. The equilibrium concentration of Bi was determined as a function of epitaxial strain state, temperature, and growth conditions. For a bulk, unstrained system, Bi in GaAs under typical growth conditions (Ga-rich and Bi-metal-rich at 400 °C) has a dilute heat of solution of 572 meV/Bi and a solubility of x=5.2×10-5 in GaAs1-xBix. However, epitaxial strain can greatly enhance this solubility, and under the same conditions an epitaxial film of GaAs1-xBix with 5% in-plane tensile strain is predicted to have a Bi solubility of x=7.3×10-3, representing approximately a hundred times increase in solubility over the unstrained bulk case. Despite these potentially large increases in solubility, the equilibrium solubility is still very low compared to values that have been achieved experimentally through nonequilibrium growth. These values of solubility are also sensitive to the choice of the Bi reference state. If the primary route for phase separation is the formation of GaBi within the same structure, rather than Bi metal, GaBi would serve as the source/sink for Bi. If GaBi is used as the Bi reference state, the epitaxial formation energy on a bulk unstrained GaAs substrate is reduced dramatically to 144 meV/Bi, yielding a Bi solubility of x=0.083 in GaAs1-xBix. These calculations suggest that Bi solubility could be greatly enhanced if Bi metal formation is inhibited and the system is forced to remain constrained to the GaAs1-xBix structure. Although GaBi is not a naturally stable compound, it could potentially be stabilized through a combination of kinetic limitations and alloying.

  4. The III-Bi binary compounds

    NASA Astrophysics Data System (ADS)

    Keen, Benjamin

    Bismuth containing III-V alloys such as GaAsBi, GaSbBi, InSbBi and InAsBi have recently become of great interest in the development of optical devices in the infrared spectrum. Difficulties in fabricating these materials stems, in part, from the lack of experimental data on the characteristics of the III-Bi family of compounds: AlBi, GaBi, and InBi. This thesis outlines the growth conditions and characteristics of the MBE deposition of InBi. To date, InBi remains the only one of the three compounds that has been experimentally reported, and the difficulties associated with the growth of AlBi and GaBi are also described herein. InBi thin films were grown on GaAs substrates at temperatures ranging from 50 °C to 100 °C. Unlike other III-V materials, which require a group V overpressure during deposition, to achieve stoichiometric quantities of indium and bismuth an In:Bi BEP ratio of 4:3 was found to be necessary. InBi samples were studied by a variety of measurement techniques, including SEM, EDX, XRD, HAXPES, and HRTEM. Films were found to grow in a 3-D Volmer-Weber mode, forming hemispherical droplets on the substrate surface. These droplets indicated clear signs of Ostwald ripening during growth, but maintained their distribution after deposition. InBi samples are believed to be semi-metallic, confirming some of the properties predicted by density functional theory (DFT) calculations. However, analysis of the crystal structure at the substrate/droplet interface indicates the epitaxial growth of InBi is in the zinc-blende configuration, instead of the PbO configuration, in direct opposition to predictions by DFT and experimental data reported from bulk crystal studies. Attempts to grow the other III-Bi materials, GaBi and AlBi, by MBE also resulted in 3-D droplet formation, but both gallium and aluminum failed to incorporate with bismuth to form a compound. Instead, the materials formed segregated regions in the droplets, clearly visible to SEM and EDX

  5. Magnetic properties of RE5Ir2X (RE = Y, Gd-Ho, X = Sn, Sb, Pb, Bi) and magnetocaloric characterization of Gd5Ir2X

    NASA Astrophysics Data System (ADS)

    Schäfer, Konrad; Schwickert, Christian; Niehaus, Oliver; Winter, Florian; Pöttgen, Rainer

    2014-09-01

    Systematic phase analytical studies of the systems RE-Ir-X (X = Sn, Pb, Sb, Bi) led to 15 new stannides, plumbides, antimonides and bismuthides with the composition RE5Ir2X. The compounds have been synthesized and characterized by X-ray powder diffraction. The structures of Gd5Ir2Sb and Dy5Ir2Bi have been refined from single crystal X-ray diffractometer data: Mo5SiB2 type, I4/mcm, a = 775.2(2), c = 1361.3(5) pm, wR2 = 0.0933, 404 F2 values, 16 variables for Gd5Ir2Sb and a = 767.5(1), c = 1368.9(3) pm, wR2 = 0.0694, 571 F2 values, 16 variables for Dy5Ir2Bi. Magnetic measurements of Gd5Ir2X (X = Sn, Pb, Sb, Bi), Tb5Ir2X (X = Sn, Pb, Sb, Bi), Dy5Ir2Pb, Dy5Ir2Bi and Ho5Ir2Pb indicate ferromagnetic transitions at TC = 154.3, 159.3, 124.4, 119.3, 99.2, 98.2, 65.5, 68.6, 45.1, 35.6 and 23.5 K, respectively. Gd5Ir2Bi and Gd5Ir2Sb show an additional antiferromagnetic transition at TN = 118.5 and 91.0 K. The magnetocaloric effect of Gd5Ir2X (X = Sn, Pb, Sb, Bi) in terms of the isothermal entropy change ΔSm is -7.3(3), -6.5(3), -8.7(3) and -9.0(3) J kg-1 K-1 at temperatures of 153, 157, 120 and 126 K for a 5 T field change. 119Sn Mössbauer spectra of Gd5Ir2Sn at 78 K show a huge transferred hyperfine field of 21.9(1) T and an isomer shift of 1.94(1) mm s-1, typical for stannides. 121Sb Mössbauer spectra of Gd5Ir2Sb at 78 K show a transferred hyperfine field of 14.2(3) T and an isomer shift of -7.45(8) mm s-1 reflecting the antimonide character.

  6. Examination of the Behavior of Bismuth in Shallow-Level Hydrothermal Ore Systems: Constraints Based on Hydrothermal Experiments at 800°C and 100 MPa

    NASA Astrophysics Data System (ADS)

    Wilmot, M. S.; Candela, P. A.; Piccoli, P. M.; Simon, A. C.; McDonough, W. F.

    2006-05-01

    The partitioning of ore metals between melt and crystals affects the concentrations of these metals in an evolving ore fluid, and therefore the efficiency of their removal from the magma by hydrothermal processes. Some porphyry-type W-Mo deposits contain recoverable amounts of Bi, whereas others contain only trace amounts. In order to determine the magmatic controls on the ratio of Bi to other commodities in these and other deposits, we examined the partitioning behavior of bismuth between melt, minerals and aqueous phases. Hydrothermal experiments were performed by using externally heated cold seal vessels and employing a double capsule technique. Experiments contained 40 mg of Bishop Tuff glass (SiO2 = 74% ) and 40 mg of either magnetite or pyrrhotite. Bi was added as elemental Bi (< 1 mg). Two different aqueous solutions were used. Initially, the added aqueous phase comprised the solutes HCl, KCl and NaCl in a molar1:1:1 ratio, with a bulk salinity of 10 wt % NaCl eq. The aqueous phase for later experiments contained only the solutes KCl and NaCl in a 1:1 molar ratio. Pre-fractured quartz was added to the experiments to trap fluid inclusions at run PTX conditions. Experiments were performed in Au or Pt capsules held inside Rene 41 cold-seal vessels at 800°C and 100 MPa for durations of up to 36 hours. Analytical data have been collected from the run product solids by using an electron probe microanalyzer (major and trace elements) and laser ablation inductively coupled plasma mass spectrometry (trace elements). Bi in Mt is found in concentrations up to 100 ppm, with higher concentrations in runs where Po decomposed to form magnetite. The Bi concentration in the glass ranges up to 100 ppm. In the Po-bearing runs, data were only collected from Po grains in the experiments containing the HCl-free aqueous solution (the Po grains in the other experiments were too small to analyze). Pyrrhotite contained 10-20 ppm Bi, whereas the glass contained 5-10 ppm. Preliminary

  7. Trimerized apolipoprotein A-I (TripA) forms lipoproteins, activates lecithin: cholesterol acyltransferase, elicits lipid efflux, and is transported through aortic endothelial cells.

    PubMed

    Ohnsorg, Pascale M; Mary, Jean-Luc; Rohrer, Lucia; Pech, Michael; Fingerle, Jürgen; von Eckardstein, Arnold

    2011-12-01

    Apolipoprotein A-I (apoA-I) exerts many potentially anti-atherogenic properties and is therefore attractive for prevention and therapy of coronary heart disease. Since induction of apoA-I production by small molecules has turned out as difficult, application of exogenous apoA-I is pursued as an alternative therapeutic option. To counteract fast renal filtration of apoA-I, a trimeric high-molecular weight variant of apoA-I (TripA) was produced by recombinant technology. We compared TripA and apoA-I for important properties in reverse cholesterol transport. Reconstituted high-density lipoproteins (rHDL) containing TripA or apoA-I together with palmitoyl-2-oleyl-phosphatidylcholine (POPC) differed slightly by size. Compared to apoA-I, TripA activated lecithin:cholesterol acyltransferase (LCAT) with similar maximal velocity but concentration leading to half maximal velocity was slightly reduced (K(m)=2.1±0.3μg/mL vs. 0.59±0.06μg/mL). Both in the lipid-free form and as part of rHDL, TripA elicited cholesterol efflux from THP1-derived macrophages with similar kinetic parameters and response to liver-X-receptor activation as apoA-I. Lipid-free TripA is bound and transported by aortic endothelial cells through mechanisms which are competed by apoA-I and TripA and inhibited by knock-down of ATP-binding cassette transporter (ABC) A1. Pre-formed TripA/POPC particles were bound and transported by endothelial cells through mechanisms which are competed by excess native HDL as well as reconstituted HDL containing either apoA-I or TripA and which involve ABCG1 and scavenger receptor B1 (SR-BI). In conclusion, apoA-I and TripA show similar in vitro properties which are important for reverse cholesterol transport. These findings are important for further development of TripA as an anti-atherosclerotic drug. PMID:21930241

  8. Tracing the origin of warm water emission through the stages of low-mass star formation

    NASA Astrophysics Data System (ADS)

    Vilhelm Persson, Magnus; Jorgensen, Jes K.; Coutens, Audrey; van Dishoeck, Ewine

    2015-08-01

    Water is a crucial molecule in the physics and chemistry of star- and planet formation, but its evolution from cold cores to disks is still poorly constrained. The gas-phase abundance of water varies between cold and warm regions up to a factor of 105 and this abundance variation makes water an excellent diagnostic of the physical structure in these sources.The origin of the warm water emission in deeply-embedded low-mass protostars is still debated, however. Current options include the innermost envelope (‘hot corino’), heated by the luminosity from the central protostar; a young disk heated by shocks related to ongoing accretion or the warm disk surface layers heated radiatively by the young star. Determining the location and kinematics of the warm water is important because it provides insights into whether water, and the locked up complex organics, actually moves from the outer envelope into the disk, and if so, whether it enters the disk mostly as gas or ice. Evolutionary models suggest that water and complex species enter the disk mostly as ice but this is so far unconfirmed observationally.Thus, in our collaboration we are undertaking a study of warm water in low-mass protostars. So far we have obtained interferometric maps of several isotopologues of water toward four deeply-embedded (i.e. Class 0) low-mass protostars with PdBI and ALMA. The detected water emission is compact toward the Class 0 sources, and a significant source of uncertainty in determining the abundances is the poorly constrained physical structure in the inner regions. Thus we try to constrain this physical structure by fitting simple disk models to the dust continuum visibilities that are left after subtracting a model of the spherical envelope. Furthermore we estimate upper limits to the warm water content toward the Class I protostars TMC-1A and L1527 from observations with PdBI.In this talk I will summarize our ongoing work in tracing the warm water emission through the various

  9. Rhenium and chalcophile elements in basaltic glasses from Ko'olau and Moloka'i volcanoes: Magmatic outgassing and composition of the Hawaiian plume

    NASA Astrophysics Data System (ADS)

    Norman, Marc D.; Garcia, Michael O.; Bennett, Victoria C.

    2004-09-01

    The behavior of chalcophile metals in volcanic environments is important for a variety of economic and environmental applications, and for understanding large-scale processes such as crustal recycling into the mantle. In order to better define the behavior of chalcophile metals in ocean island volcanoes, we measured the concentrations of Re, Cd, Bi, Cu, Pb, Zn, Pt, S, and a suite of major elements and lithophile trace elements in moderately evolved (6-7% MgO) tholeiitic glasses from Ko'olau and Moloka'i volcanoes. Correlated variations in the Re, Cd, and S contents of these glasses are consistent with loss of these elements as volatile species during magmatic outgassing. Bismuth also shows a good correlation with S in the Ko'olau glasses, but undegassed glasses from Moloka'i have unexpectedly low Bi contents. Rhenium appears to have been more volatile than either Cd or Bi in these magmas. Undegassed glasses with 880-1400 ppm S have 1.2-1.5 ppb Re and 130-145 ppb Cd. In contrast, outgassed melts with low S (<200 ppm) are depleted in these elements by factors of 2-5. Key ratios such as Re/Yb and Cu/Re are fractionated significantly from mantle values. Copper, Pb, and Pt contents of these glasses show no correlation with S, ruling out segregation of an immiscible magmatic sulfide phase as the cause of these variations. Undegassed Hawaiian tholeiites have Re/Yb ratios significantly higher than those of MORB, and extend to values greater than that of the primitive mantle. Loss of Re during outgassing of ocean island volcanoes, may help resolve the apparent paradox of low Re/Os ratios in ocean island basalts with radiogenic Os isotopic compositions. Plume source regions with Re/Yb ratios greater than that of the primitive mantle may provide at least a partial solution to the "missing Re" problem in which one or more reservoirs with high Re/Yb are required to balance the low Re/Yb of MORB. Lithophile trace element compositions of most Ko'olau and Moloka'i tholeiites are

  10. X-ray Fluorescence Investigation of Ordered Intermetallic Phases as Electrocatalysts towards the Oxidation of Small Organic Molecules

    SciTech Connect

    Liu, Yi; Lowe, Michael A.; Finkelstein, Ken D.; Dale, Darren S.; DiSalvo, Francis J.; Abruña, Héctor D.

    2010-10-13

    The composition of ordered intermetallic nanoparticles (PtBi and PtPb) has been quantitatively studied by in situ X-ray fluorescence (XRF) during active electrochemical control in solutions of supporting electrolyte and small organic molecules (SOMs). Because the Pt Lβ1,2 lines and the Bi Lα1,2 lines are only separated by 200 eV, an energy-dispersive detector and a multiple-channel analyzer (MCA) were used to record the major fluorescent emission lines from these two elements. The molar ratios of platinum to the less-noble elements (Bi, Pb) in the nanoparticles dramatically changed as a function of the applied upper limit potentials (Eulp) in cyclic voltammetric (CV) characterization. Similar to previous investigations for bulk intermetallic surfaces, the less-noble elements leached out from the surfaces of the intermetallic nanoparticles. For PtBi nanoparticles, the ratios of fluorescence intensities of Pt/Bi in the samples were 0.42, 0.96, and 1.36 for Eulp=+0.40, +0.80, and 1.20 V, respectively, while cycling the potential from -0.20 V to the Eulp value for 10 cycles. The leaching-out process of the less-noble elements occurred at more negative Eulp values than expected. After cycling to relatively positive Eulp values, nonuniform PtM (M=Bi of Pb) nanoparticles formed with a Pt-rich shell and intermetallic PtM core. When the supporting solutions contained active fuel molecules in addition to the intermetallic nanoparticles (formic acid for PtBi, formic acid and methanol for PtPb), kinetic stabilization effects were observed for Eulp=+0.80 V, in a way similar to the response of the bulk materials. It was of great importance to quantitatively explore the change in composition and structure of the intermetallic nanoparticles under active electrochemical control. More importantly, this approach represents a simple, universal, and multifunctional method for the study of multi

  11. Synthesis and Crystal Structures of Hg 6Sb 5Br 7, Hg 6As 4BiCl 7, and Hg 6Sb 4BiBr 7, Built of a Polycationic Mercury-Pnictide Framework with Trapped Anions

    NASA Astrophysics Data System (ADS)

    Beck, Johannes; Hedderich, Sylvia; Neisel, Udo

    2000-11-01

    Hg6Sb5Br7, Hg6As4BiCl7, and Hg6Sb4BiBr7 were prepared from stoichiometric mixtures of Hg2X2, HgX2 (X=Cl, Br), As, Sb, and Bi in sealed, evacuated glass ampoules in temperature gradients 260→240°C for Hg6Sb5Br7, 340→320°C for Hg6As4BiCl7, and 290→270°C for Hg6Sb4BiBr7. All compounds crystallize in the cubic space group Paoverline3 with Z=4 and the lattice constants a=13.003(1) Å for Hg6Sb5Br7, a=12.178(2) Å for Hg6As4BiCl7, and a=12.998(4) Å for Hg6Sb4BiBr7. The structures have been solved based on single-crystal X-ray diffraction data and refined to R(F)=0.0431, 666 Fo for Hg6Sb5Br7, R(F)=0.0478, 690 Fo for Hg6As4BiCl7, and R(F)=0.0444, 840 Fo for Hg6Sb4BiBr7 with 30 parameters for each refinement. The structures are characterized by a three-dimensional polycationic framework of pnictide dumb-bells (As-As distance 2.43 Å, Sb-Sb distance 2.78 Å), each connected by six mercury atoms to six neighbored As2/Sb2 groups. There are two different cages in the framework; one type is occupied by nearly regular MX6 octahedra (M=Sb,Bi; X=Cl, Br), the other by halide ions. The three compounds crystallize closely related to Cd7P4Cl6, which contains a similar polycationic framework of P2 dumb-bells connected by Cd, but with only one type of cage occupied by octahedral [CdCl6]4- ions. The interactions between the atoms of the polycationic framework and the anions are very weak. The observed diamagnetism of all three compounds is in agreement with the ionic formulas (Hg6Sb4)4+[SbBr6]3-Br-, (Hg6As4)4+[BiCl6]3-Cl-, and (Hg6Sb4)4+[BiBr6]3-Br-.

  12. Geochemical studies in the Indian Pass and Picacho Peak Bureau of Land Management Wilderness study areas, imperial county, Southern California

    USGS Publications Warehouse

    Smith, D.B.; Berger, B.R.; Tosdal, R.M.

    1987-01-01

    The U.S. Geological Survey has conducted geochemical studies in the Indian Pass (CDCA-355), 124 km2, and Picacho Peak (CDCA-355A), 23 km2, Wilderness Study Areas (WSA's) as part of a program to evaluate the mineral resource potential of designated areas in the California Desert Conservation Area. These two WSA's are of particular interest because they lie within a region which has intermittently produced significant quantities of Au since the mid-1800's, and is currently the site of much exploration activity for additional Au resources. Within a 15-km radius of the WSA's, there is one actively producing gold mine, a major deposit which began production in 1986, and one recently announced discovery. In the reconnaissance geochemical surveys of the two WSA's - 177 ??m (-80 mesh) stream sediments, heavy-mineral concentrates from stream sediments, and rocks were prepared and analyzed. Four areas of possible exploration interest were identified within the WSA's. The first area is characterized by anomalous W and Bi in nonmagnetic heavy-mineral concentrates, and is underlain primarily by the Mesozoic Orocopia Schist which has been intruded by monzogranite of Oligocene age. Alteration and mineralization appear to be localized near the intrusive contact. The mineralized rock at the surface contains secondary Cu and Fe minerals where the monzogranite intrudes the metabasite horizons of the Orocopia Schist and scheelite where the monzogranite intrudes marble within the Orocopia Schist. The second area is characterized by anomalous As, Sb, Ba, B, and Sr in nonmagnetic heavy-mineral concentrates and by anomalous As in - 177 ??m stream sediments. Geologically, this area is underlain by metasedimentary and metavolcanic rocks of Jurassic(?) age; a biotite monzogranite of Jurassic(?) age; and Tertiary volcanic and hypabyssal rocks composed of flows, domes, and tuffs of intermediate to silicic composition. All these rock types are cut by a set of north-south-striking normal faults

  13. Relationship between expression levels and atherogenesis in scavenger receptor Class B, Type I Transgenics

    SciTech Connect

    Ueda, Yukihiko; Gong, Elaine; Royer, Lori; Cooper, Philip N.; Francone, Omar L; Rubin, Edward M.

    2000-03-15

    Both in vitro and in vivo studies of SR-BI have implicated it as a likely participant in the metabolism of HDL cholesterol. To investigate SR-BI's effect on atherogenesis we examined two lines of SR-BI transgenic mice with high (10-fold increases) and low (2-fold increases) in SR-BI expression in an inbred mouse background hemizygous for a human apo B transgene. Unlike non-HDL cholesterol levels which minimally differed in the various groups of animals, HDL cholesterol levels were inversely related to SR-BI expression. Mice with the low expression SR-BI transgene had a 50% reduction in HDL cholesterol while the high expression SR-BI transgene was associated with two-fold decreases in HDL as well as dramatic alterations in HDL composition and size including the near absence of a-migrating particles as determined by 2-dimensional electrophoresis. The low expression SR-BI/apo B transgenics had more than a two-fold decrease in the development of diet induced fatty streak lesions compared t o the apo B transgenics (4448{+-}1908 {mu}m2/aorta to 10133 {+-} 4035 {mu}m2/aorta; p<0.001), while the high expression SR-BI/apo B transgenics had an atherogenic response similar to that of the apo B transgenics (14692{+-}7238 {mu}m2/aorta) but three-fold greater than the low SR-BI/apo B mice (p<0.001). The prominent anti-atherogenic effect of moderate SR-BI expression provides in vivo support for the hypothesis that HDL functions to inhibit atherogenesis through its interactions with SR-BI in facilitating reverse cholesterol transport. The failure of the high SR-BI/apo B transgenics to have similar or even greater reductions in atherogenesis suggests that the changes resulting from extremely high SR-BI expression including dramatic changes in lipoproteins may have both pro- and anti-atherogenic consequences illustrating the complexity of the relationship between SR-BI and atherogenesis.

  14. Production of actinium-225 for alpha particle mediated radioimmunotherapy.

    PubMed

    Boll, Rose A; Malkemus, Dairin; Mirzadeh, Saed

    2005-05-01

    The initial clinical trials for treatment of acute myeloid leukemia have demonstrated the effectiveness of the alpha emitter (213)Bi in killing cancer cells. Bismuth-213 is obtained from a radionuclide generator system from decay of 10-days (225)Ac parent. Recent pre-clinical studies have also shown the potential application of both (213)Bi, and the (225)Ac parent radionuclide in a variety of cancer systems and targeted radiotherapy. This paper describes our five years of experience in production of (225)Ac in partial support of the on-going clinical trials. A four-step chemical process, consisting of both anion and cation exchange chromatography, is utilized for routine separation of carrier-free (225)Ac from a mixture of (228)Th, (229)Th and (232)Th. The separation of Ra and Ac from Th is achieved using the marcoporous anion exchange resin MP1 in 8M HNO(3) media. Two sequential MP1/NO(3) columns provide a separation factor of approximately 10(6) for Ra and Ac from Th. The separation of Ac from Ra is accomplished on a low cross-linking cation exchange resin AG50-X4 using 1.2M HNO(3) as eluant. Two sequential AG50/NO(3) columns provide a separation factor of approximately 10(2) for Ac from Ra. A 60-day processing schedule has been adopted in order to reduce the processing cost and to provide the highest levels of (225)Ac possible. Over an 8-week campaign, a total of approximately 100 mCi of (225)Ac (approximately 80% of the theoretical yield) is shipped in 5-6 batches, with the first batch typically consisting of approximately 50 mCi. After the initial separation and purification of Ac, the Ra pool is re-processed on a bi-weekly schedule or as needed to provide smaller batches of (225)Ac. The averaged radioisotopic purity of the (225)Ac was 99.6 +/- 0.7% with a (225)Ra content of < or =0.6%, and an average (229)Th content of (4(-4)(+5)) x 10(-5)%. PMID:15763472

  15. Novel apo E-derived ABCA1 agonist peptide (CS-6253) promotes reverse cholesterol transport and induces formation of preβ-1 HDL in vitro

    DOE PAGESBeta

    Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; Genest, Jacques; Zhu, Xuewei

    2015-07-24

    Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from themore » carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These mechanisms are

  16. High Prevalence of Antibiotic-Resistant Bacterial Infections Among Patients With Cirrhosis at a US Liver Center

    PubMed Central

    TANDON, PUNEETA; DELISLE, ANGELA; TOPAL, JEFFREY E.; GARCIA–TSAO, GUADALUPE

    2013-01-01

    BACKGROUND & AIMS There are limited data on the prevalence or predictors of antibiotic-resistant bacterial infections (AR-BI) in hospitalized patients with cirrhosis in North America. Exposure to systemic antibiotics is a risk factor for AR-BI; however, little is known about the effects of the increasingly used oral nonabsorbed antibiotics. METHODS We analyzed data from patients with cirrhosis and bacterial infections hospitalized in a liver unit at a US hospital between July 2009 and November 2010. Multivariate logistic regression was used to determine predictors of AR-BI. Data were analyzed on the first bacterial infection of each patient (n = 115), and a sensitivity analysis was performed on all infectious episodes per patient (n = 169). RESULTS Thirty percent of infections were nosocomial. Urinary tract infections (32%) and spontaneous bacterial peritonitis (24%) were most common. Of the 70 culture-positive infections, 33 (47%) were found to be antibiotic resistant (12 were vancomycin-resistant Enterococci, 9 were extended-spectrum β-lactamase–producing Enterobacteriaceae, 7 were quinolone-resistant gram-negative rods, and 5 were methicillin-resistant Staphylococcus aureus). Exposure to systemic antibiotics within 30 days before infection was associated independently with AR-BI, with an odds ratio (OR) of 13.5 (95% confidence interval [CI], 2.6–71.6). Exposure to only nonabsorbed antibiotics (rifaximin) was not associated with AR-BI (OR, 0.4; 95% CI, 0.04–2.8). In a sensitivity analysis, exposure to systemic antibiotics within 30 days before infection and nosocomial infection was associated with AR-BI (OR, 5.2; 95% CI, 1.5–17.7; and OR, 4.2; 95% CI, 1.4–12.5, respectively). CONCLUSIONS The prevalence of AR-BI is high in a US tertiary care transplant center. Exposure to systemic antibiotics within 30 days before infection (including those used for prophylaxis of spontaneous bacterial peritonitis), but not oral nonabsorbed antibiotics, is associated

  17. The multi-phase winds of Markarian 231: from the hot, nuclear, ultra-fast wind to the galaxy-scale, molecular outflow

    NASA Astrophysics Data System (ADS)

    Feruglio, C.; Fiore, F.; Carniani, S.; Piconcelli, E.; Zappacosta, L.; Bongiorno, A.; Cicone, C.; Maiolino, R.; Marconi, A.; Menci, N.; Puccetti, S.; Veilleux, S.

    2015-11-01

    Mrk 231 is a nearby ultra-luminous IR galaxy exhibiting a kpc-scale, multi-phase AGN-driven outflow. This galaxy represents the best target to investigate in detail the morphology and energetics of powerful outflows, as well as their still poorly-understood expansion mechanism and impact on the host galaxy. In this work, we present the best sensitivity and angular resolution maps of the molecular disk and outflow of Mrk 231, as traced by CO(2-1) and (3-2) observations obtained with the IRAM/PdBI. In addition, we analyze archival deep Chandra and NuSTAR X-ray observations. We use this unprecedented combination of multi-wavelength data sets to constrain the physical properties of both the molecular disk and outflow, the presence of a highly-ionized ultra-fast nuclear wind, and their connection. The molecular CO(2-1) outflow has a size of 1 kpc, and extends in all directions around the nucleus, being more prominent along the south-west to north-east direction, suggesting a wide-angle biconical geometry. The maximum projected velocity of the outflow is nearly constant out to 1 kpc, thus implying that the density of the outflowing material must decrease from the nucleus outwards as r-2. This suggests that either a large part of the gas leaves the flow during its expansion or that the bulk of the outflow has not yet reached out to 1 kpc, thus implying a limit on its age of 1 Myr. Mapping the mass and energy rates of the molecular outflow yields dot {M} OF = [500-1000] M⊙ yr-1 and Ėkin,OF = [7-10] × 1043 erg s-1. The total kinetic energy of the outflow is Ekin,OF is of the same order of the total energy of the molecular disk, Edisk. Remarkably, our analysis of the X-ray data reveals a nuclear ultra-fast outflow (UFO) with velocity -20 000 km s-1, dot {M}UFO = [0.3-2.1] M⊙ yr-1, and momentum load dot {P}UFO/ dot {P}rad = [0.2-1.6]. We find Ėkin,UFO Ėkin,OF as predicted for outflows undergoing an energy conserving expansion. This suggests that most of the UFO

  18. Filament fragmentation in high-mass star formation

    NASA Astrophysics Data System (ADS)

    Beuther, H.; Ragan, S. E.; Johnston, K.; Henning, Th.; Hacar, A.; Kainulainen, J. T.

    2015-12-01

    Context. Filamentary structures in the interstellar medium are crucial ingredients of the star formation process. They fragment to form individual star-forming cores, and at the same time they may also funnel gas toward the central gas cores, providing an additional gas reservoir. Aims: We want to resolve the length scales for filament formation and fragmentation (resolution ≤0.1 pc), in particular the Jeans length and cylinder fragmentation scale. Methods: We have observed the prototypical high-mass star-forming filament IRDC 18223 with the Plateau de Bure Interferometer (PdBI) in the 3.2 mm continuum and N2H+(1-0) line emission in a ten-field mosaic at a spatial resolution of ~ 4'' (~14 000 au). Results: The dust continuum emission resolves the filament into a chain of at least 12 relatively regularly spaced cores. The mean separation between cores is ~0.40(± 0.18) pc. While this is approximately consistent with the fragmentation of an infinite, isothermal, and gravitationally bound gas cylinder, a high mass-to-length ratio of M/l ≈ 1000 M⊙ pc-1 requires additional turbulent and/or magnetic support against radial collapse of the filament. The N2H+(1-0) data reveal a velocity gradient perpendicular to the main filament. Although rotation of the filament cannot be excluded, the data are also consistent with the main filament being comprised of several velocity-coherent subfilaments. Furthermore, this velocity gradient perpendicular to the filament resembles results toward Serpens south that are interpreted as signatures of filament formation within magnetized and turbulent sheet-like structures. Lower-density gas tracers ([CI] and C18O) reveal a similar red- and blueshifted velocity structure on scales around 60'' east and west of the filament. This may tentatively be interpreted as a signature of the large-scale cloud and the smaller scale filament being kinematically coupled. We do not identify a velocity gradient along the axis of the filament. This may

  19. The massive disk around the young B-star AFGL 490

    NASA Astrophysics Data System (ADS)

    Schreyer, Katharina; Semenov, Dmitry; Henning, Thomas; Pavlyuchenkov, Yaroslav; Dullemond, Cornelius

    The AFGL 490 is a key target in the class of deeply embedded young stellar objects with masses of 8x10 Msol being in a transition stage to the pre-main-sequence Herbig Be stars. We observe this system at sub-arcsecond resolution with the Plateau de Bure Interferometer (PdBI) in the C17O(2-1) transition in order to confirm the presence of a rotating disk. The C17O(2-1) data show clear evidence for a rotating ~ 1 500 AU disk centered at the the 1 mm continuum point source. We model these data iteratively. First, the physical structure of the disk is obtained using a two-dimensional radiative transfer code. Second, with this model in hand, we calculate time-dependent abundances in the disk using a gas-grain chemical network. Finally, the beam-convolved C17O(2-1) interferometric map is synthesized by a 2D line transfer code, and these results are compared with the observations in the step-by-step way (Semenov et al. 2005). We estimate that (1) the disk inclination angle is 30 ± 5◦, (2) its positional angle is 150 ± 10◦, (3) the disk is in Keplerian rotation, (4) it has a radius of about 1 400 AU, and (5) the disk mass is about 0.2-0.4 Msol (depending on the assumed surface density gradient p ~ -1). This is in contrast to the value of 4 ± 2 Msol estimated from the intensity of the PdBI 1 mm continuum emission within 1000 AU around the star, and ~ 8 Msol for the mass of the gas located within about 4 000 AU around the star, as it has been found using our CS(2-1) PdBI data (Schreyer et al. 2002). It is interesting that the geometry of the detected C17O emission map speaks in favor of a larger inclination angle, > 60◦. Thus, the C17O interferometric map traces the densest part of a more extended and likely asymmetric disklike structure. Moreover, we find clear indication for on-going accretion in this object, since the detected PdBI CH3OH J=2(0,2)-1(0,1) A+ emission lines show characteristic inverse P Cygni profiles. Given the large mass of the circumstellar gas

  20. Experimental Study on Flow Technology and Steel Corrosion of Lead-Bismuth

    SciTech Connect

    Minoru Takahashi; Hiroshi Sekimoto; Kotaro Ishikawa; Naoki Sawada; Tadashi Suzuki; Susumu Yoshida; Toyohiko Yano; Masamitsu Imai; Koji Hata; Suizheng Qiu

    2002-07-01

    For the feasibility study of Pb-Bi-cooled fast reactors (FR) and the Pb-Bi target of accelerator-driven nuclear transmutation systems, Pb-Bi flow technologies were developed and steel corrosion behavior in a Pb-Bi flow was investigated using a Pb-Bi circulation loop. The performance of an electro-magnetic flow meter with electrically insulated electrodes plated with Rh was better than those of conventional and tubular types. Oxygen concentration was controlled by continuous injection of Ar, H{sub 2} and H{sub 2}O mixture gas into the Pb-Bi flow. In order to have desired oxygen potential, the partial pressure ratio of P{sub H{sub 2}}/P{sub H{sub 2}}{sub O} was chosen in the range from 0.12 to 2.2 by bubbling the mixture of Ar and H{sub 2} in water columns at the room temperature. By injecting the mixture gas into the loop for sufficient time, the oxygen potentials measured by the oxygen sensor made of solid electrolyte ZrO{sub 2}-Y{sub 2}O{sub 3} agreed well with those in the injected gas mixture. In the first corrosion test, steels were exposed to a Pb-Bi flow at the temperature of 550 deg. C, the velocity of 2 m/s and the oxygen concentration of {approx}5.0x10{sup -7} wt.% for 959 hours. It was found that the weight loss was larger in the order of SS316, low Cr steel (SCM420) and high Cr steels (STBA26, SUS405, SUS430). Corrosion was suppressed by a Cr oxide layer for high Cr steels. A porous layer was formed on SS316 surface due to high solubility of Ni in Pb-Bi,. In the second corrosion test, the oxygen concentration was kept at 3.6x10{sup -7} wt.% by injecting Ar, H{sub 2} and H{sub 2}O mixture gas into a Pb-Bi flow, and steels were exposed to a Pb-Bi flow at the temperature of 550 deg. C, the velocity of 2 m/s for 1000 hours. Serious erosion damage was observed in SCM420 at the entrance, and some erosion damages appeared in low Cr steels: SCM420, F82H, STBA26 and HCM12 downstream. Crack type damage was observed on the surface of HCM12, and pitting-type damage

  1. About contaminant element composition of roadside dust samples from Budapest and Seoul, including Pt and Pd

    NASA Astrophysics Data System (ADS)

    Sager, M.; Chon, H. T.; Marton, L.

    2012-04-01

    both cities, and moderate pollution for roadside dusts from the rest of Hungary. Pt and Pd concentrations were strongly intercorrelated, but not with the pollution index. In dusts from Budapest, Pt and Pd were strongly correlated with each other, and moderately just with Sn and Bi. In Seoul dusts, Pt was strong positively correlated with Ba-Cu-Fe-Ir-Mo-Pd-Sb, and slightly with Cr-Fe-Mo-Ni, but negatively with Ca-Cd-Hg-Pb. Pd in Seoul dusts, however, was positively correlated just with Pt and Ir, but negatively with K-Li-Na-Pb-Sr.

  2. Trace-element fingerprints of chromite, magnetite and sulfides from the 3.1 Ga ultramafic-mafic rocks of the Nuggihalli greenstone belt, Western Dharwar craton (India)

    NASA Astrophysics Data System (ADS)

    Mukherjee, Ria; Mondal, Sisir K.; González-Jiménez, José M.; Griffin, William L.; Pearson, Norman J.; O'Reilly, Suzanne Y.

    2015-06-01

    andesitic melts, suggesting that magnetite crystallized from an evolved gabbroic melt. Enrichments of Ni, Co, Te, As and Bi in disseminated millerite and niccolite occurring within chromitites, and in disseminated bravoite within magnetites, reflect element mobility during serpentinization. Monosulfide solid solution inclusions within pyroxenes (altered to actinolite) in pyroxenite, and interstitial pyrites and chalcopyrites in magnetite, retain primary characteristics except for Fe-enrichment in chalcopyrite, probably due to sub-solidus re-equilibration with magnetite. Disseminated sulfides are depleted in platinum-group elements (PGE) due to late sulfide saturation and the PGE-depleted nature of the mantle source of the sill-like ultramafic-mafic plutonic rocks in the Nuggihalli greenstone belt.

  3. Sources and Spatial Distribution of Metal Pollutants in Soils near the El Paso Smelter: A Forensic Study with Pb and Pu Isotopes.

    NASA Astrophysics Data System (ADS)

    Ketterer, Michael; Moan, Matthew; Gremillion, Paul

    2010-05-01

    Lead and copper smelting has been conducted at El Paso since the late 1800's, and as a result, environmental media near the smelter have become contaminated. A study has been conducted to investigate the sources and spatial distribution of metal pollutants (Pb, Cd, Zn, Hg, As, Cu) and concomitant tracers (Ag, In, Sb, Bi) in soils from the smelter vicinity. Sampled locations were residential and non-residential locations in El Paso (Texas, USA), Anapra (New Mexico, USA) and Ciudad Juarez (Chihuahua, Mexico). Lead isotope studies indicate that the soil Pb is derived from smelting, and is consistent with two-component mixing between lead ores from Chihuahua (northern Mexico) having 206Pb/204Pb of 18.6 - 18.8 and ores from the Hanover, New Mexico (USA) mining district with 206Pb/204Pb of ~ 17.6. The Pb isotope results also exclude other common anthropogenic Pb sources such as paint and gasoline emissions as being major contributors. Concentrations of Hg and Pb of up to 10 and 11,000 ppm were found in surface soils within 1 km of the smelter. The metal concentration results clearly indicate that soils near the smelter (< 5 km) exhibit much higher concentrations of smelter-related elements than do soils from control locations (> 10 km distant). A general trend of decreasing concentrations vs. distance from the smelter was also observed. However, the results indicate that metal concentrations vary widely even at a fixed distance from the smelter point source. This phenomenon results from a combination of natural and anthropogenic processes that disturb and re-distribute soils in the surface environment. The site conditions consist of a very arid environment with little vegetation cover that is frequently disturbed by high winds and severe episodic rainfall. To study these effects, we have investigated stratospheric fallout plutonium (239+240Pu) as a proxy measure of disturbed vs. undisturbed soil conditions. The premise is that 'undisturbed' locations will have high 239

  4. Acid test of joint technical and biological measures in slope stabilisation - Impact analysis of the heavy rainstorm event in August 2005

    NASA Astrophysics Data System (ADS)

    Graf, F.; Böll, A.

    2009-04-01

    The persisting and heavy rainstorms from 20th to 22nd August in 2005 resulted in loss of human lives and tremendous damage on infrastructure all over Switzerland. Many of the measures taken hitherto to protect against such natural hazards were stressed to their limits or even beyond due to water saturation of the soils and extreme discharges of the torrents. This particular configuration offered the possibility to investigate the reliability of technical and biological measures taken within the scope of slope stabilisation, torrent and gully control. In the context of a joint project the ancient sliding area "Schwandrübi" in Dallenwil (Switzerland) providing joint technical and biological measures was chosen to address aspects concerning the reliability of technical supporting structures, the development of biological measures in the course of time and their performance under the extreme impact as well as the effects of biological measures on the stability of slopes. During 1981 and 1982 joint technical and biological measures had been taken on a large scale with minor follow-ups shortly after to stabilise the "Schwandrübi". The underlying strategy was based on several pilot surveys as thorough soil analysis, e.g. grain size distribution and determination of the angle of internal friction (Φ') related to the porosity (n) and the dry unit weight (γ), respectively. Basically, the spatial arrangement of the gabions was in accordance with the theoretical guidelines. However, based on the angle of internal friction (Φ') determined on the loose moraine soil material, it was not possible to meet the soil mechanical criterion of inclination between the constructions in all cases. Regardless of the extreme impact during the rainstorm (~100-year event), no serious damage occurred neither on the roughly 25-year old gabions nor on the torrent control structures. The recalculated peak discharge in the outlet channel was ~60 m3s-1 superimposed by high bed load

  5. Trace element distribution, with a focus on gold, in copper-rich and zinc-rich sulfide chimneys from Brothers submarine volcano, Kermadec arc

    NASA Astrophysics Data System (ADS)

    Berkenbosch, H. A.; de Ronde, C. E.; McNeill, A.; Goemann, K.; Gemmell, J. B.

    2012-12-01

    . These tellurides are the first gold-bearing phase to be identified in these chimneys, and the Bi-Au association suggests that gold-enrichment up to 91 ppm is due to scavenging by liquid bismuth. To better understand the mineral associations and zonation of these and other trace elements within the chimney walls, we have undertaken element mapping on the four different chimneys types with both X-Ray fluorescence microscopy using synchrotron radiation and with Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). For example, in a chalcopyrite-rich chimney, visibly laminated chalcopyrite in the interior contains bands with a magmatic suite of elements including Co, Mo, Ag, Te, Au, and Bi. In comparison in a sphalerite-chalcopyrite-rich chimney, Au is again associated with minor Cu, although not with Bi and Te indicating alternative methods of gold transport and deposition are dominant. Element mapping allows us to better understand the physico-chemical gradients within chimney walls, as well as metal sources and transportation, and depositional processes.

  6. Volatile Reservoirs Below The Upper Lunar Mantle And Their Incompatibility With The Giant Impact Hypothesis

    NASA Astrophysics Data System (ADS)

    Schmitt, H. H.

    2011-12-01

    Separate accretion and capture is a physically plausible alternative to the giant Earth impact hypothesis for the origin of the Moon. Like the capture hypothesis, giant impact relies on gravitational interaction of the Earth and a smaller planetesimal under very specific orbital encounter conditions. In addition to questions about the physics of debris re-aggregation in Earth-orbit, the giant impact hypothesis, as currently formulated by computer models, fails a critical reality check; namely, the Moon contains reservoirs of volatiles that would have been dispersed at ejection temperatures predicted by the models... Researchers have previously noted that concentrations of many volatile elements in both the Apollo 17 and Apollo 15 pyroclastic glass samples indicate the existence of volatile reservoirs at depth. Both the orange and green glasses are enriched over mare basalts by factors >100 in Cl, F, Br, Zn, Ge, Dc, Tl, and Ag and by factors >10 in Pb, Ga, Sb, Bi, In, Au, Ni, Se, Te, and Cu. These elements exist almost entirely in the non-glass components of the pyroclastic samples. The recent identification of significant water within the Apollo 17 orange pyroclastic glasses further emphasizes the existence of volatile reservoirs in the lunar mantle... No evidence exists that the volatiles in the vesicles of mare basalts, derived by partial melting of a differentiated and solidified lunar magma ocean (upper mantle), were comparable to those in the pyroclastic glasses. Accretionary thermal effects that produced the magma ocean, combined with low lunar gravity, to would have depleted primordial volatiles. Any remaining magma ocean water would be converted to hydrogen and FeO by migration of early-formed, broadly disseminated, immiscible FexNiySz liquid. The reservoirs for the pyroclastic volatiles, therefore, would be below about 500km (lower mantle), that is, below the base of the original magma ocean. Relatively inert hydrogen and carbon monoxide probably made up

  7. Influence of Bi-related impurity states on the bandgap and spin-orbit splitting energy of dilute III-V-Bi alloys: InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix

    NASA Astrophysics Data System (ADS)

    Samajdar, D. P.; Dhar, S.

    2016-01-01

    Valence Band Anticrossing (VBAC) Model is used to calculate the changes in band structure of Bi containing alloys such as InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix due to the incorporation of dilute concentrations of bismuth. The coupling parameter CBi which gives the magnitude of interaction of Bi impurity states with the LH, HH and SO sub bands in VBAC depends on the increase in the HH/LH related energy level EHH/LH+, location of the Bi related impurity level EBi and valence band offset ΔEVBM between the endpoint compounds in the corresponding III-V-Bi. The reduction in band gap as well as the enhancement of the spin-orbit splitting energy is well explained using this model and the calculated results are compared with the results of Virtual Crystal Approximation (VCA) and Density Functional Theory (DFT) calculations, as well as with the available experimental data and are found to have good agreement. The incorporation of Bi mainly perturbs the valence band due to the interaction of the Bi impurity states with the HH, LH and SO bands. The lowering of the conduction band minimum (CBM) due to VCA is added with the upward movement of the HH/LH bands to get the total reduction in band gap for the bismides. The valence band shifts of 31.9, 32.5, 20.8 and 12.4 meV/at%Bi for InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix respectively constitute 65, 76, 59 and 31% of the total band gap reduction and the rest is the contribution of the conduction band shift. The spin-orbit splitting energy also shows significant increase with the maximum change in InPBi and the minimum in InSbBi. The same is true for Ga containing bismides if we make a comparison with the available values for GaAsBi and GaPBi with that of GaSbBi. It has also been observed that the increase in splitting energy is greater in case of the bismides such as InAsBi, InPBi and GaAsBi than the bismides such as InSbBi and GaSbBi with the parent substrates having higher values of splitting energy. This may