Sample records for group v elements

  1. Cluster and Heterometallic Alkoxide Derivatives of Rhenium and d-Elements of V–VI Groups

    Microsoft Academic Search

    Dmitri V. Drobot; Gulaim A. Seisenbaeva; Vadim G. Kessler; P. A. Scheglov; O. A. Nikonova; S. N. Michnevich; O. V. Petrakova

    2009-01-01

    The paper represents a listing of results obtained by developing the original methods of controlled synthesis of cluster and\\u000a mono-, bi- and trimetallic oxo-alkoxide derivatives of rhenium and d-elements of V–VI groups. The developed techniques of\\u000a the synthesis of metal alkoxides include: (1) anodic dissolution of the metals in the alcohol media; (2) direct reaction of\\u000a the rhenium (VII) oxide

  2. Atomic strings of group IV, III-V, and II-VI elements

    Microsoft Academic Search

    S. Tongay; E. Durgun; S. Ciraci

    2004-01-01

    A systematic first-principles study of atomic strings made by group IV, III-V, and II-VI elements has revealed interesting mechanical, electronic, and transport properties. The double bond structure underlies their unusual properties. We found that linear chain of C, Si, Ge, SiGe, GaAs, InSb, and CdTe are stable and good conductor, although their parent diamond (zincblende) crystals are covalent (polar) semiconductors

  3. Lattice location of the group V elements Sb, As, and P in ZnO

    E-print Network

    Wahl, Ulrich; Mendonça, Tânia; Decoster, Stefan

    2010-01-01

    Modifying the properties of ZnO by means of incorporating antimony, arsenic or phosphorus impurities is of interest since these group V elements have been reported in the literature among the few successful p-type dopants in this technologically promising II-VI compound. The lattice location of ion-implanted Sb, As, and P in ZnO single crystals was investigated by means of the electron emission channeling technique using the radioactive isotopes 124Sb, 73As and 33P and it is found that they preferentially occupy substitutional Zn sites while the possible fractions on substitutional O sites are a few percent at maximum. The lattice site preference is understandable from the relatively large ionic size of the heavy mass group V elements. Unfortunately the presented results cannot finally settle the interesting issue whether substitutional Sb, As or P on oxygen sites or Sb(Zn)?2V(Zn), As(Zn)?2V(Zn) or P(Zn)?2V(Zn) complexes (as suggested in the literature) are responsible for the acceptor action. However, ...

  4. Lattice location of the group V elements As and Sb in ZnO

    E-print Network

    Wahl, Ulrich; Decoster, Stefan; Mendonça, Tânia

    2009-01-01

    The lattice locations of the potential p-type dopants arsenic and antimony in single-crystalline ZnO were studied by means of the electron emission channeling method following the implantation of radioactive 73As and 124Sb isotopes. The majority of the implanted As and Sb probe atoms was found to occupy substitutional Zn sites, with the possible fraction on substitutional O sites being at maximum a few percent. The obtained results illustrate the difficulty in introducing oversized group V impurities on O sites and thus put further into question whether these elements may act as simple chemical dopants in ZnO.

  5. Atomically thin group v elemental films: theoretical investigations of antimonene allotropes.

    PubMed

    Wang, Gaoxue; Pandey, Ravindra; Karna, Shashi P

    2015-06-01

    Group V elemental monolayers including phosphorene are emerging as promising 2D materials with semiconducting electronic properties. Here, we present the results of first-principles calculations on stability, mechanical and electronic properties of 2D antimony (Sb), antimonene. Our calculations show that free-standing ? and ? allotropes of antimonene are stable and semiconducting. The ?-Sb has a puckered structure with two atomic sublayers and ?-Sb has a buckled hexagonal lattice. The calculated Raman spectra and STM images have distinct features thus facilitating characterization of both allotropes. The ?-Sb has nearly isotropic mechanical properties, whereas ?-Sb shows strongly anisotropic characteristics. An indirect-direct band gap transition is expected with moderate tensile strains applied to the monolayers, which opens up the possibility of their applications in optoelectronics. PMID:25955131

  6. A comprehensive ab initio study of doping in bulk ZnO with group V elements

    NASA Astrophysics Data System (ADS)

    Petretto, Guido; Bruneval, Fabien

    2014-03-01

    Zinc-oxyde, despite being a promising candidate for several electronic applications, up to now has provided several challenges to the scientific community, both from an experimental and theoretical point of view. In fact, a reliable p-type doping still has not been achieved and standard density functional theory (DFT) calculations has often provided unsatisfactory results and failed to help in the search for better configurations to obtain such property. To solve the band gap underestimation problem we have made use of the HSE hybrid functional, tuning the admixing parameter to match the experimental band gap. Within this framework, we extensively studied the formation and transition energies of group V elements related defects. These include simple substitutional defects XO, XZn (X=N, P, As, Sb) and complexes of the form XZn-2VZn and XZn-VZn. The stability of these complexes is also addressed. We show that it is unlikely to obtain good acceptor states from these elements due to deep transition energies and the presence of donor-like defects.

  7. Theoretical and Materials Chemistry of Some Group III and V Elements

    Microsoft Academic Search

    John Arthur Glass Jr.

    1993-01-01

    The theoretical and material aspects of some group III and V compounds have been investigated. Phosphaborane clusters were investigated by modified neglect of differential overlap semi-empirical molecular orbital calculations (MNDO -SCF) to better understand important structural, electronic, and thermodynamic properties of these experimentally difficult species. The structural, thermodynamic and electronic properties of 111 phosphapentaborane cluster compounds have been calculated via

  8. Atomic chains of group-IV elements and III-V and II-VI binary compounds studied by a first-principles pseudopotential method

    NASA Astrophysics Data System (ADS)

    Senger, R. T.; Tongay, S.; Durgun, E.; Ciraci, S.

    2005-08-01

    Using the first-principles plane wave pseudopotential method we have studied structural, electronic, and transport properties of atomic chains of group-IV elements and group III-V and group II-VI binary compounds. Several materials which are insulating or semiconducting in bulk are found to be metallic in nanowire structures. Our calculations reveal that monatomic chains of Si, Ge, and Sn elements, and of binary compounds such as InP, GaAs, and AlSb, are stable and metallic. On the other hand, compound wires of BN, SiC, GaN, ZnSe, and several others have semiconducting or insulating properties. Ideal mechanical strength calculations show that some of these atomic chains can sustain strains of up to ?=0.3 . We have presented ab initio electron transport calculations for Si and AlP linear chain segments in between Al electrodes. Conductance of Si monatomic chains displays some nontrivial features as the number of atoms in the chain is varied or as the chain is strained. In addition to single atomic chain structures, junctions and grid structures of Si are investigated.

  9. On dominance and minuscule Weyl group elements

    E-print Network

    Gashi, Qëndrim R

    2009-01-01

    Fix a Dynkin diagram and let p be a coweight. When does there exist an element w of the corresponding Weyl group such that w is p-minuscule and w(p) is dominant? We answer this question for general Coxeter groups. We express and prove these results using a variant of Mozes's game of numbers.

  10. Substantial enhancement in intrinsic coercivity on M-type strontium hexaferrite through the increase in magneto-crystalline anisotropy by co-doping of group-V and alkali elements

    SciTech Connect

    Ahn, Kyunghan, E-mail: kyunghan.ahn@samsung.com; Ryu, Byungki; Korolev, Dmitry; Jae Kang, Young [Materials R and D Center, Samsung Advanced Institute of Technology, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of)] [Materials R and D Center, Samsung Advanced Institute of Technology, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of)

    2013-12-09

    The effect of d{sup 1} impurity doping in Sr-hexaferrite (SrM) on the magnetic anisotropy is investigated. First-principles calculations revealed that group-V elements (V, Nb) are stabilized with co-doping of alkali elements. Na{sup 1+}/K{sup 1+} doping at Sr{sup 2+}-site is found to be critical to form the d{sup 1} impurities at Fe-site. Experimentally, Na–V doped SrM shows the intrinsic coercivity of ?5.4 kOe, which is ?300% enhancement compared to undoped SrM and comparable value to La–Co co-doped SrM. Finally, the spin-orbit coupling from non-vanishing angular momentum of d{sup 1} impurity in SrM should be a main factor for such a substantial improvement of intrinsic coercivity.

  11. Properties of Group Five and Group Seven transactinium elements

    SciTech Connect

    Wilk, Philip A.

    2001-05-01

    The detection and positive identification of the short-lived, low cross section isotopes used in the chemical studies of the heaviest elements are usually accomplished by measuring their alpha-decay, thus the nuclear properties of the heaviest elements must be examined simultaneously with their chemical properties. The isotopes 224 Pa and 266,267 Bh have been studied extensively as an integral part of the investigation of the heaviest members of the groups five and seven of the periodic table. The half-life of 224 Pa was determined to be 855 plus/minus19 ms by measuring its alpha-decay using our rotating wheel, solid state detector system at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Protactinium was produced by bombardment of a bismuth target. New neutron rich isotopes, 267 Bh and 266 Bh, were produced in bombardments of a 249 Bk target and their decay was observed using the rotating wheel system. The 266 Bh that was produced decays with a half-life of approximately 1 s by emission of alpha particles with an average energy of 9.25 plus/minus 0.03 MeV. 267 Bh was observed to decay with a 17 s half-life by emission of alpha-particles with an average energy of 8.83 plus/minus 0.03 MeV. The chemical behavior of hafnium, Ha (element 105) was investigated using the fast on-line continuous liquid extraction and detection system SISAK-LISSY. Hafnium was not observed in this experiment following transport and extraction. Protactinium was used as on-line test of the apparatus to determine the experimental efficiency of the entire system. Unfortunately, the amount of protactinium observed after the extraction, compared to the amount produced, was extremely small, only 2.5%. The extraction of the protactinium isotope indicated the efficiency of the apparatus was too low to observe the extraction of hafnium. The chemical behavior of oxychloride compounds of bohrium was investigated by isothermal gas adsorption chromatography in a quartz column at 180, 150, and 75 C. It was found to be less volatile than the corresponding compounds of the lighter group seven homologues, rhenium and technetium, which had been measured previously with the same apparatus. Assuming the bohrium compound to be BhO3Cl, the evaluated standard adsorption enthalpy, and delta-Hads, of BhO3Cl on the quartz surface was calculated from Monte Carlo fits to the volatility data to be -75 kJ/mol. The adsorption enthalpies for TcO3Cl and ReO3Cl are -51 and -61 kJ/mol respectively.

  12. Cold Fusion Production and Decay of Neutron-Deficient Isotopes of Dubnium and Development of Extraction Systems for Group V Elements

    SciTech Connect

    Gates, Jacklyn M.

    2008-07-31

    Excitation functions for the 1n and 2n exit channels of the 208Pb(51V,xn)259-xDb reaction were measured. A maximum cross section of the 1n exit channel of 2070+1100/-760 pb was measured at an excitation energy of 16.0 +- 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660+450/-370 pb was measured at 22.0 +- 1.8 MeV excitation energy. The 1n excitation function for the 209Bi(50Ti,n)258Db reaction was remeasured, resulting in a cross section of 5480+1730/1370 pb at an excitation energy of 16.0 +- 1.6 MeV. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier. The extraction of niobium (Nb) and tantalum (Ta) from hydrochloric acid and mixed hydrochloric acid/lithium chloride media by bis(2-ethylhexyl) hydrogen phosphate (HDEHP) and bis(2-ethylhexyl) hydrogen phosphite (BEHP) was studied. The goal of the experiments was to find a system that demonstrates selectivity among the members of group five of the Periodic Table and is also suitable for the study of dubnium (Db, Z = 105). Experiments with niobium and tantalum were performed with carrier (10-6 M), carrier free (10-10 M) and trace (10-16 M) concentrations of metal using hydrochloric acid solution with concentrations ranging from 1 - 11 M. The extraction of niobium and tantalum from mixed hydrochloric acid/lithium chloride media by HDEHP and BEHP as a function of hydrogen ion (H+) concentration was also investigated. The data obtained are used as the basis to discuss the speciation of niobium and tantalum under the conditions studied and to evaluate possible extraction mechanisms. The 74Se(18O,p3n)88gNb excitation function was measured to determine the best energy for producing the 88Nb used in chemistry experiments. A maximum cross section of 495 +- 5 mb was observed at an 18O energy of 74.0 MeV. The half life of 88gNb was measured and determined to be 14.56 +- 0.11 min.

  13. INVERTIBLE AND NILPOTENT ELEMENTS IN THE GROUP ALGEBRA OF A UNIQUE PRODUCT GROUP

    E-print Network

    Neher, Erhard

    INVERTIBLE AND NILPOTENT ELEMENTS IN THE GROUP ALGEBRA OF A UNIQUE PRODUCT GROUP ERHARD NEHER Abstract. We describe the nilpotent and invertible elements in group alge- bras k[G] for k a commutative. A fundamental problem in the theory of group algebras is to determine their units = invertible elements

  14. New Elemental Abundances for V1974 Cygni

    E-print Network

    K. M. Vanlandingham; G. J. Schwarz; S. N. Shore; S. Starrfield; R. M. Wagner

    2005-01-31

    We present a new analysis of existing optical and ultraviolet spectra of the ONeMg nova V1974 Cygni 1992. Using these data and the photoionization code Cloudy, we have determined the physical parameters and elemental abundances for this nova. Many of the previous studies of this nova have made use of incorrect analyses and hence a new study was required. Our results show that the ejecta are enhanced, relative to solar, in helium, nitrogen, oxygen, neon, magnesium and iron. Carbon was found to be subsolar. We find an ejected mass of ~2x10e-4 solar masses. Our model results fit well with observations taken at IR, radio, sub-millimeter and X-ray wavelengths.

  15. Distributed process groups in the V Kernel

    Microsoft Academic Search

    David R. Cheriton; Willy Zwaenepoel

    1985-01-01

    The V kernel supports an abstraction of processes, with operations for interprocess communication, process management, and memory management. This abstraction is used as a software base for constructing distributed systems. As a distributed kernel, the V kernel makes intermachine boundaries largely transparent.In this environment of many cooperating processes on different machines, there are many logical groups of processes. Examples include

  16. The Heavy Element Abundance in Groups of Galaxies

    NASA Technical Reports Server (NTRS)

    David, Laurence

    2000-01-01

    Over the past few years we have analyzed a sample of clusters observed by the Advanced Spacecraft for Cosmology Astrophysics (ASCA) X-ray satellite. We performed spatially resolved X-ray spectroscopy of a sample of 18 relaxed clusters of galaxies with gas temperatures below 4 keV. The spectral analysis was done using ASCA/SIS (Solid state Imaging Spectrometer) data combined with imaging data from ROSAT/PSPC (German acronym for X-ray satellite/Position Sensitive Proportional Counter) and Einstein/IPC (Imaging Proportional Counter) observations. We derived temperature profiles using single-temperature fits for all of the clusters in the sample, and also corrected for the presence of cold gas in the center of so-called 'cooling flow' clusters. For all of the clusters in the sample we derived Si and Fe abundance profiles. For a few of the clusters we also were able to derive Ne and S abundance profiles. We compared the elemental abundances derived at similar overdensities in all of the clusters in the sample. We also compared element mass-to-light ratios for the entire sample. We concluded that the preferential accretion of low entropy, low abundance gas into the potentials of groups and cold clusters can explain most of the observed trends in metallicity. In addition, we discussed the importance of preheating of the intracluster medium by Type II supernovae on the cluster scaling relations.

  17. CONSTRUCTING ELEMENTS IN SHAFAREVICH-TATE GROUPS OF MODULAR MOTIVES

    Microsoft Academic Search

    NEIL DUMMIGAN; WILLIAM STEIN; MARK WATKINS

    2003-01-01

    We study Shafarevich-Tate groups of motives attached to modular forms on ¡0(N) of weight bigger than 2. We deduce a criterion for the existence of nontrivial elements of these Shafarevich-Tate groups, and give 16 examples in which a strong form of the Beilinson-Bloch conjecture implies the existence of such elements. We also use modular symbols and observations about Tam- agawa

  18. Platinum group elements in the environment and their health risk

    Microsoft Academic Search

    Khaiwal Ravindra; László Bencs; René Van Grieken

    2004-01-01

    Accumulation of platinum group elements (PGEs) in the environment has been increased over the time. Catalytic converters of modern vehicles are considered to be the main sources of PGE pollution, since the correlation is between the Pt:Rh ratios in various environmental compartments and in converter units. The present literature survey shows that the concentration of these metals has increased significantly

  19. The strong Bass conjecture for group elements of finite order and for residually finite groups

    E-print Network

    Schick, Thomas

    The strong Bass conjecture for group elements of finite order and for residually finite is a function on the conjugacy classes of elements of G with values in k. The strong Bass conjecture is never invertible). In this note, we prove the strong Bass conjecture for arbitrary integral

  20. Effects of element type and spatial grouping on symmetry detection.

    PubMed

    Locher, P J; Wagemans, J

    1993-01-01

    The influence of local and global attributes of symmetric patterns on the perceptual salience of symmetry was investigated. After tachistoscopic viewing, subjects discriminated between symmetric and either random patterns (experiment 1) or their perturbed counterparts (experiment 2) created by replacing one third of the mirror element-pairs of symmetric stimuli with 'random' elements. In general, it was found that perceptibility of symmetry, measured by response time and detection accuracy, was not influenced in a consistent way by type of pattern element (dots or line segments oriented vertically, horizontally, obliquely, or in all three orientations about the symmetry axis). Nor did axis orientation (vertical, horizontal, oblique), advance knowledge of axis orientation, practice effects, or subject sophistication differentially affect detection. A highly salient global percept of symmetry emerged, on the other hand, when elements were clustered together within a pattern, or grouped in symmetric pairs along a single symmetry axis or two orthogonal axes. Results suggest that mirror symmetry is detected preattentively, presumably by some kind of integral code which emerges from the interaction between display elements and the way they are organized spatially. It is proposed that symmetry is coded and signalled by the same spatial grouping processes as those responsible for construction of the full primal sketch. PMID:8414882

  1. Homocatenation of Metal and Metalloid Main Group Elements

    NASA Astrophysics Data System (ADS)

    Hill, Michael S.

    Interest in poly(diorgano)silanes, catenated silicon compounds and heavier element analogues of alkanes has derived largely from their 1-dimensional delocalisation across the Si-Si ? framework, which affords similar properties observed for polyene and unsaturated "all organic" polymers. Although not so widely recognised or studied, similar "?-delocalised" activity may also be observed for homocatenated species of other p-block elements. In this study, a foundation for an understanding of the phenomenon of ?-delocalisation is provided through consideration of the structures, methods of synthesis and electronic behaviour of the well-established poly(diorgano)silanes. Synthetic and theoretical developments relating to analogous derivatives based upon silicon's heavier group 14 congeners are then reviewed along with the more limited examples of catenated compounds among the heavier elements of groups 15 and 13. This coverage does not dwell upon detailed aspects of structure or electronic behaviour for the individual compounds and classes of compound included. Rather, the intention is to promote something of a phenomenological awareness of a series of superficially disparate chemical systems and to encourage a more widespread appreciation of the implication that, in not displaying ?-delocalisation, it is the elements of the first full period that display the more unusual or anomalous behaviour.

  2. Homoleptic low-valent polyazides of group 14 elements.

    PubMed

    Peerless, Benjamin; Keane, Theo; Meijer, Anthony J H M; Portius, Peter

    2015-05-01

    First examples of coordinatively unsaturated, homoleptic azido complexes of low-valent group 14 elements are reported. A simple strategy uses low-valent precursors, ionic azide transfer reagents and bulky cations to obtain salt-like compounds containing E(N3)3(-) of Ge(II)/Sn(II) which are fully characterised, including XRD. Remarkably, these compounds are kinetically stable at r.t. and isolable in sub-gram quantities. PMID:25773494

  3. Two types of meta-crystals for IV group elements: Density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Wu, Jianbao; Zhang, Weiyi; Mi, Yiming; Zhang, Chaoming

    2013-02-01

    Using density function theory (DFT) implemented in VASP package, we find two new type of meta-crystals constructed by IV group elements: Si-568 and Ge-568. The calculational results show that Si-568 has a band gap of 0.09 eV estimated by DFT, while Ge-568 behaves metallic. These two new types of nano-structures both can be created via experimentally observed di-vacancies (DVs) and Stone-Thrower-Wales (STW) defect.

  4. Experimental constraints on the partitioning of rhenium and some platinum-group elements between

    E-print Network

    Rudnick, Roberta L.

    Experimental constraints on the partitioning of rhenium and some platinum-group elements between in controlling the behavior of rhenium and the platinum group elements (PGEs) during basalt petrogenesis; siderophile element 1. Introduction Rhenium and the platinum group elements (PGEs) are valuable tracers

  5. Platinum-group element abundance patterns in different mantle environments

    PubMed

    Rehkamper; Halliday; Barfod; Fitton; Dawson

    1997-11-28

    Mantle-derived xenoliths from the Cameroon Line and northern Tanzania display differences in their platinum-group element (PGE) abundance patterns. The Cameroon Line lherzolites have uniform PGE patterns indicating a homogeneous upper mantle over several hundreds of kilometers, with approximately chondritic PGE ratios. The PGE patterns of the Tanzanian peridotites are similar to the PGE systematics of ultramafic rocks from ophiolites. The differences can be explained if the northern Tanzanian lithosphere developed in a fluid-rich suprasubduction zone environment, whereas the Cameroon Line lithosphere only experienced melt extraction from anhydrous peridotites. PMID:9374452

  6. Intergenic transcription through a Polycomb group response element counteracts silencing

    PubMed Central

    Schmitt, Sabine; Prestel, Matthias; Paro, Renato

    2005-01-01

    Polycomb group response elements (PREs) mediate the mitotic inheritance of gene expression programs and thus maintain determined cell fates. By default, PREs silence associated genes via the targeting of Polycomb group (PcG) complexes. Upon an activating signal, however, PREs recruit counteracting trithorax group (trxG) proteins, which in turn maintain target genes in a transcriptionally active state. Using a transgenic reporter system, we show that the switch from the silenced to the activated state of a PRE requires noncoding transcription. Continuous transcription through the PRE induced by an actin promoter prevents the establishment of PcG-mediated silencing. The maintenance of epigenetic activation requires transcription through the PRE to proceed at least until embryogenesis is completed. At the homeotic bithorax complex of Drosophila, intergenic PRE transcripts can be detected not only during embryogenesis, but also at late larval stages, suggesting that transcription through endogenous PREs is required continuously as an anti-silencing mechanism to prevent the access of repressive PcG complexes to the chromatin. Furthermore, all other PREs outside the homeotic complex we tested were found to be transcribed in the same tissue as the mRNA of the corresponding target gene, suggesting that anti-silencing by transcription is a fundamental aspect of the cellular memory system. PMID:15741315

  7. Matrix elements of the Argonne v18 potential

    E-print Network

    Bogdan Mihaila

    2011-11-17

    We discuss two approaches to the calculation of matrix elements of the Argonne v18 potential. The first approach is applicable in the case of a single-particle basis of harmonic-oscillator wave functions. In this case we use the Talmi transformation, implemented numerically using the Moshinsky transformation brackets, to separate the center-of-mass and relative coordinates degrees of freedom. Integrals involving the radial part of the potential are performed using Gauss-Hermite quadrature formulas, and convergence is achieved for sets of at least 512 points. We validate the calculation of matrix elements of the Argonne v18 potential using a second approach suitable for the case of an arbitrary functional form of the single-particle wave functions. When the model space is represented in terms of harmonic-oscillator wave functions, results obtained using these two approaches are shown to to be identical within numerical accuracy.

  8. Matrix elements of the Argonne v18 potential

    E-print Network

    Mihaila, Bogdan

    2011-01-01

    We discuss two approaches to the calculation of matrix elements of the Argonne v18 potential. The first approach is applicable in the case of a single-particle basis of harmonic-oscillator wave functions. In this case we use the Talmi transformation, implemented numerically using the Moshinsky transformation brackets, to separate the center-of-mass and relative coordinates degrees of freedom. Integrals involving the radial part of the potential are performed using Gauss-Hermite quadrature formulas, and convergence is achieved for sets of at least 512 points. We validate the calculation of matrix elements of the Argonne v18 potential using a second approach suitable for the case of an arbitrary functional form of the single-particle wave functions. When the model space is represented in terms of harmonic-oscillator wave functions, results obtained using these two approaches are shown to to be identical within numerical accuracy.

  9. A renormalisation group method. V. A single renormalisation group step

    E-print Network

    David C. Brydges; Gordon Slade

    2014-11-25

    This paper is the fifth in a series devoted to the development of a rigorous renormalisation group method applicable to lattice field theories containing boson and/or fermion fields, and comprises the core of the method. In the renormalisation group method, increasingly large scales are studied in a progressive manner, with an interaction parametrised by a field polynomial which evolves with the scale under the renormalisation group map. In our context, the progressive analysis is performed via a finite-range covariance decomposition. Perturbative calculations are used to track the flow of the coupling constants of the evolving polynomial, but on their own perturbative calculations are insufficient to control error terms and to obtain mathematically rigorous results. In this paper, we define an additional non-perturbative coordinate, which together with the flow of coupling constants defines the complete evolution of the renormalisation group map. We specify conditions under which the non-perturbative coordinate is contractive under a single renormalisation group step. Our framework is essentially combinatorial, but its implementation relies on analytic results developed earlier in the series of papers. The results of this paper are applied elsewhere to analyse the critical behaviour of the 4-dimensional continuous-time weakly self-avoiding walk and of the 4-dimensional $n$-component $|\\varphi|^4$ model. In particular, the existence of a logarithmic correction to mean-field scaling for the susceptibility can be proved for both models, together with other facts about critical exponents and critical behaviour.

  10. A Renormalisation Group Method. V. A Single Renormalisation Group Step

    NASA Astrophysics Data System (ADS)

    Brydges, David C.; Slade, Gordon

    2015-05-01

    This paper is the fifth in a series devoted to the development of a rigorous renormalisation group method applicable to lattice field theories containing boson and/or fermion fields, and comprises the core of the method. In the renormalisation group method, increasingly large scales are studied in a progressive manner, with an interaction parametrised by a field polynomial which evolves with the scale under the renormalisation group map. In our context, the progressive analysis is performed via a finite-range covariance decomposition. Perturbative calculations are used to track the flow of the coupling constants of the evolving polynomial, but on their own perturbative calculations are insufficient to control error terms and to obtain mathematically rigorous results. In this paper, we define an additional non-perturbative coordinate, which together with the flow of coupling constants defines the complete evolution of the renormalisation group map. We specify conditions under which the non-perturbative coordinate is contractive under a single renormalisation group step. Our framework is essentially combinatorial, but its implementation relies on analytic results developed earlier in the series of papers. The results of this paper are applied elsewhere to analyse the critical behaviour of the 4-dimensional continuous-time weakly self-avoiding walk and of the 4-dimensional -component model. In particular, the existence of a logarithmic correction to mean-field scaling for the susceptibility can be proved for both models, together with other facts about critical exponents and critical behaviour.

  11. Doping of indium phosphide with group IV elements

    SciTech Connect

    Zakharenkov, L.F.; Samorukov, B.E.; Zykov, A.M.

    1985-06-01

    This paper studies the doping of single crystals of indium phosphide (InP) with group IV elements using data obtained by measuring the total charge concentration of additives and carriers. Single crystals of indium phosphide were grown by the Czochralski method from liquid melts with a liquid hermetic seal in quartz cubicles. The total impurity concentration was determined by atomic-absorption analysis with + or - 10% error. In order to explain the behavior of germanium and tin in indium phosphide, the authors consider the bond energies of additives in indium phosphide and their tetrahedral radii. The authors conclude that the established higher amphoteric character of germanium with respect to tin is probably explained by the moduli of elasticity of the doped crystal.

  12. Comprehensive Analyses of the Spectra of Iron-group Elements

    NASA Astrophysics Data System (ADS)

    Nave, Gillian; Sansonetti, Craig J; Pickering, Juliet C; Liggins, Florence

    2014-06-01

    For many decades, the Atomic Spectroscopy Group at NIST has measured atomic data of vital use to astronomy and other fields using high resolution spectrometers that are found in few other places in the world. These now include the 2-m Fourier transform (FT) spectrometer covering the region 285 nm to 5500 nm, the FT700 vacuum ultraviolet (VUV) FT spectrometer covering the region 143 nm to 900 nm, and a 10.7-m normal incidence spectrograph (NIVS) covering 30 nm to 500 nm. Recent work focused on the measurement and analysis of wavelengths and energy levels of iron-group elements to provide extensive data for the analysis of astrophysical spectra. Our comprehensive linelist for Fe II from 90 nm to 5500 nm contains over 13 600 lines with order of magnitude improvements in the wavelengths compared to previous work [Nave & Johansson, ApJSS 204, 1(2013)]. The spectra were observed in high-current continuous and pulsed hollow cathode (HCL) discharges using FT spectrometers and our NIVS spectrograph. A similar analysis of Cr II contains over 5300 lines and extends the knowledge of this spectrum to the previously unobserved region between 731 nm at 5500 nm [Sansonetti, Nave, Reader & Kerber, ApJSS 202, 15 (2012); Sansonetti & Nave, ApJSS (in prep.)]. Our analysis of the Co III spectrum contains 750 lines observed in Penning discharge lamps and an additional 900 lines compiled from previous work, including Ritz wavelengths, optimized energy levels, and calculated log(gf) values [Smillie, Pickering, Nave & Smith, ApJSS (in prep.)]. NIST and ICL are currently collaborating to complete the measurement and analysis of wavelengths, energy levels, and hyperfine structure parameters for all singly-ionized iron-group elements of astrophysical interest, covering the wavelength range 80 nm to 5500 nm. This project uses archival data from FT spectrometers at NIST, ICL and Kitt Peak National Observatory, with additional spectra of HCL and Penning discharge sources taken using our FT and NIVS spectrometers. Current work includes the spectra of Mn I, Mn II, Ni II, Sc II, and Co III. This work was partially supported by NASA, the STFC and PPARC (UK), the Royal Society of the UK, and the Leverhulme Trust.

  13. Determination of the CKM Element V(Ub)

    SciTech Connect

    Fortin, Dominique; /Victoria U.

    2007-04-06

    The precise determination of the CKM matrix element |V{sub ub}| is crucial in testing the Standard Model mechanism for CP violation. From a sample of 88 million B{bar B} pairs collected with the BABAR detector, charmless semileptonic B decays are selected using simultaneous requirements on the electron energy, E{sub e}, and the invariant mass squared of the electron-neutrino pair, q{sup 2}. The partial branching fraction, unfolded for detector effects, is determined in a region of the q{sup 2}-E{sub e} plane where the dominating semileptonic decays to charm mesons are highly suppressed. Theoretical calculations based on the Heavy Quark Expanion allows for a determination of |V{sub ub}| = (3.95 {+-} 0.27{sub -0.42}{sup +0.58} {+-} 0.25) x 10{sup -3}, where the errors represent experimental, heavy quark parameters and theoretical uncertainties, respectively.

  14. Design, synthesis, and properties of phthalocyanine complexes with main-group elements showing main absorption and fluorescence beyond 1000 nm.

    PubMed

    Furuyama, Taniyuki; Satoh, Koh; Kushiya, Tomofumi; Kobayashi, Nagao

    2014-01-15

    We present a comprehensive description of the unique properties of newly developed phthalocyanines (Pcs) containing main-group elements that absorb and emit in the near-IR region. Group 16 (S, Se, and Te) elements and group 15 (P, As, and Sb) elements were used as peripheral and central (core) substituents. With the introduction of group 16 elements into free-base Pc, a red-shift of the Q-band was observed, as a result of the electron-donating ability of group 16 elements particularly at the ? positions. An X-ray crystallographic analysis of ?-ArS-, ArSe-, and ArTe-linked free-base Pcs was also successfully performed, and the relationship between structure and optical properties was clarified. When a group 15 element ion was introduced into the center of the Pc ring, the resulting Pcs showed a single Q-band peak beyond 1000 nm (up to 1056 nm in CH2Cl2). In particular, [(ArS)8PcP(OMe)2](+) and [(ArS)8PcAs(OMe)2](+) exhibited a distinct fluorescence in the 960-1400 nm region with moderate quantum yields. The atomic radius of the group 15 element is important for determining the Pc structure, so that this can be controlled by the choice of group 15 elements. Electrochemical data revealed, while MO calculations suggested, that the red-shift of the Q-band is attributable to a decrease of the HOMO-LUMO gap due to significant and moderate stabilization of the LUMO and HOMO, respectively. The effect of peripheral substutuents and a central P(V) ion on the Q-band shift was independently predicted by MO calculations, while the magnitude of the total calculated shift was in good agreement with the experimental observations. The combination of spectral, electrochemical, and theoretical considerations revealed that all of the central group 15 elements, peripheral group 16 elements, and their positions are necessary to shift the Q-band beyond 1000 nm, indicating that the substitution effects of group 15 and 16 elements act synergistically. The Pcs having Q-bands beyond 1000 nm in this study also had stability under aerobic conditions comparative to that of CuPc, which is presently being widely used in consumer products. PMID:24328229

  15. Summary of the TeV33 working group

    SciTech Connect

    Bagley, P.P.; Bieniosek, F.M.; Colestock, P. [and others

    1996-10-01

    This summary of the TeV33 working group at Snowmass reports on work in the areas of Tevatron store parameters, the beam-beam interaction, Main Injector intensity (slip stacking), antiproton production, and electron cooling.

  16. Bioaccessibility of platinum group elements in automotive catalytic converter particulates.

    PubMed

    Turner, Andrew; Price, Simon

    2008-12-15

    The bioaccessibilities of the platinum group elements (PGE): Rh, Pd, and Pt; and the catalyzator poison, Pb, have been determined in particles derived from milled automotive catalytic converters using a physiologically based extraction test (PBET) that simulates, sequentially, the chemical conditions encountered in the human stomach and intestine. PGE accessibility, relative to total metal concentration, was generally less than a few percent, but increased in the stomach with decreasing pH (from 4 to 1) and/or increasing chloride concentration, and with decreasing particle concentration. In most cases, bioaccessibility increased from the acidic stomach to the neutral, carbonate-rich intestine. Bioaccessibility of Pb displayed similar pH and particle concentration dependencies to PGE in the stomach, but this metal exhibited significantly greater mobilization (up to 80%) overall and a reduction in accessibility from the stomach to intestine. Reaction kinetics of PGE dissolution in the stomach at pH 2.5 were modeled using a combined surface reaction-diffusion controlled mechanism with rate constants of 0.068, 0.031, and 0.015 (microg L(-1))(-1) h(-1) for Rh, Pd, and Pt, respectively. For Pb, however, mobilization proceeded via a different mechanism whose time-dependence was fitted with an empirical, logarithmic equation. Overall, PGE bioaccessibility appeared to be controlled by dissolution rates of metallic nanoparticles in the stomach, and solubility and kinetic constraints on inorganic species (chlorides, hydroxychlorides, and carbanatochlorides) and undefined organic complexes formed in the simulated gastrointestinal tract. Further studies are required to elucidate any effects engendered by the long-term oral exposure of small quantities of these species. PMID:19174929

  17. The elemental composition of the Sun. II. The iron group elements Sc to Ni

    NASA Astrophysics Data System (ADS)

    Scott, Pat; Asplund, Martin; Grevesse, Nicolas; Bergemann, Maria; Sauval, A. Jacques

    2015-01-01

    We redetermine the abundances of all iron group nuclei in the Sun, based on neutral and singly-ionised lines of Sc, Ti, V, Mn, Fe, Co and Ni in the solar spectrum. We employ a realistic 3D hydrodynamic model solar atmosphere, corrections for departures from local thermodynamic equilibrium (NLTE), stringent line selection procedures and high quality observational data. We have scoured the literature for the best quality oscillator strengths, hyperfine constants and isotopic separations available for our chosen lines. We find log ?Sc = 3.16 ± 0.04, log ?Ti = 4.93 ± 0.04, log ?V = 3.89 ± 0.08, log ?Cr = 5.62 ± 0.04, log ?Mn = 5.42 ± 0.04, log ?Fe = 7.47 ± 0.04, log ?Co = 4.93 ± 0.05 and log ?Ni = 6.20 ± 0.04. Our uncertainties factor in both statistical and systematic errors (the latter estimated for possible errors in the model atmospheres and NLTE line formation). The new abundances are generally in good agreement with the CI meteoritic abundances but with some notable exceptions. This analysis constitutes both a full exposition and a slight update of the preliminary results we presented in Asplund et al. (2009, ARA&A, 47, 481), including full line lists and details of all input data we employed. Tables 1-3 are available in electronic form at http://www.aanda.org

  18. Elliptic Weyl Group Elements and Unipotent Isometries with P = 2

    E-print Network

    Lusztig, George

    Let G be a classical group over an algebraically closed field of characteristic 2 and let C be an elliptic conjugacy class in the Weyl group. In a previous paper the first named author associated to C a unipotent conjugacy ...

  19. Rhenium-osmium isotope systematics and platinum group element concentrations: Loess and the upper continental crust

    Microsoft Academic Search

    Bernhard Peucker-Ehrenbrink; Bor-ming Jahn

    2001-01-01

    [1] Abstract: We investigate the use of loess as a proxy for the concentration and isotopic composition of highly siderophile elements, specifically Os, in the upper continental crust. The 187 Os\\/ 188 Os, platinum group element, and Re concentrations of 16 loess samples from China, Europe, and South America, previously analyzed for major, trace element, and Sr and Nd isotope

  20. Virtually free pro-p groups whose torsion elements have finite centralizers

    E-print Network

    Zalesskii, Pavel

    Virtually free pro-p groups whose torsion elements have finite centralizers W. Herfort University-DF, Brazil pz@mat.unb.br July 15, 2006 Abstract It is shown that a finitely generated virtually free pro-p group G with finite centralizers of its torsion elements is the free pro-p product of finite p

  1. Elements of Mathematics, Book 10: Groups and Rings.

    ERIC Educational Resources Information Center

    Exner, Robert; And Others

    One of 12 books developed for use with the core material (Book O) of the Elements of Mathematics Program, this text covers material well beyond the scope of the usual secondary mathematics sequences. These materials are designed for highly motivated students with strong verbal abilities; mathematical theories and ideas are developed through…

  2. Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006

    USGS Publications Warehouse

    Seidelmann, P.K.; Archinal, B.A.; A'Hearn, M.F.; Conrad, A.; Consolmagno, G.J.; Hestroffer, D.; Hilton, J.L.; Krasinsky, G.A.; Neumann, G.; Oberst, J.; Stooke, P.; Tedesco, E.F.; Tholen, D.J.; Thomas, P.C.; Williams, I.P.

    2007-01-01

    Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report introduces improved values for the pole and rotation rate of Pluto, Charon, and Phoebe, the pole of Jupiter, the sizes and shapes of Saturn satellites and Charon, and the poles, rotation rates, and sizes of some minor planets and comets. A high precision realization for the pole and rotation rate of the Moon is provided. The expression for the Sun's rotation has been changed to be consistent with the planets and to account for light travel time ?? 2007 Springer Science+Business Media B.V.

  3. Current Light Elements of the ? Scuti Star V393 Carinae

    NASA Astrophysics Data System (ADS)

    Axelsen, R. A.

    2014-12-01

    V393 Carinae is a 7th magnitude delta Scuti star which has a principal period of 0.1413 d and an amplitude of 0.2 magnitude in V. Previous publications have suggested the existence of a second period, but its duration has so far evaded discovery. In view of the uncertainty, and since the only two papers on this star were published in 1984 and 2001, DSLR photometry was performed to obtain time series data. Images were taken during 6 nights from December 2013 to March 2014. The data were analyzed using a discrete Fourier transform, which yielded a principal frequency of 7.07727 (± 0.00005) cycles/day, corresponding to a period of 0.141297 (± 0.000001) day. Prewhitening for this frequency revealed a harmonic frequency precisely twice that of the principal, but no further dominant frequencies could be found. O-C diagrams suggested that it would appropriate to derive a new linear ephemeris from three times of maximum obtained by another author from 1977 to 1979, combined with the 6 new times of maximum reported in this paper. The light elements are: Tmax = HJD 2456732.0484 (6) + 0.14129328 (1). It is concluded that the current principal period of this star is almost identical to the period determined approximately 37 years ago. The issue of a second period is unresolved. None was detected, but it cannot be excluded that a second pulsation frequency of low amplitude could be hidden due to a low signal to noise ratio.

  4. Platinum-group element resources in podiform chromitites from California and Oregon.

    USGS Publications Warehouse

    Page, N.J.; Singer, D.A.; Moring, B.C.; Carlson, C.A.; McDade, J.M.; Wilson, S.A.

    1986-01-01

    Assays of Pt, Pd, Rh and Ir from approx 280 podiform chromite deposits in Palaeozoic and Mesozoic ophiolites are statistically analysed to estimate their possible by-product value from mining the chromite. The platinum-group elements occur in discrete platinum-group minerals, and in solid solution in Cu-Ni-Fe sulphides. Low grades and small amounts of total platinum-group elements in podiform chromite deposits imply a small resource. -G.J.N.

  5. Distribution of platinum group elements and other traffic related elements among different plants along some highways in Germany

    Microsoft Academic Search

    Rumiana Djingova; Petya Kovacheva; Gerhard Wagner; Bernd Markert

    2003-01-01

    Using ICP-MS and ICP-AES platinum group elements (Pt, Pd, Rh, Ru and Ir) and Ce, La, Nd, Pb and Zr have been determined in street dust, Taraxacum officinale (dandelion), Plantago lanceolata (plantain), Lolium multiflorum (annual ryegrass), Rhytidiadelphus squarrosus (moss) and Vascellum pratense (mushrooms) collected along highways and streets in Germany during 1999. Among the plants Taraxacum officinale (dandelion) reflects most

  6. Re-187 Os-187 Isotopic and Highly Siderophile Element Systematics of Group IVB Irons

    NASA Technical Reports Server (NTRS)

    Honesto, J.; McDonough, W. F.; Walker, R. J.; McCoy, T. J.; Ash, R. D.

    2005-01-01

    Study of the magmatic iron meteorite groups permits constraints to be placed on the chemical and isotopic composition of parent bodies, and the timing of, and crystal-liquid fractionation processes involved in the crystallization of asteroidal cores. Here we examine Re-Os isotopic and trace elemental systematics of group IVB irons. Compared to most irons, the irons comprising this group are enriched in some of the most refractory siderophile elements, yet highly-depleted in most volatile siderophile elements. These characteristics have been attributed to processes such as high temperature condensation of precursor materials and oxidation in the parent body. Most recently it has been suggested that both processes may be involved in the chemical complexity of the group. Here, high precision isotopic and highly siderophile element (HSE) concentrations are used to further examine these possible origins, and the crystallization history of the group. In addition, we have begun to assess the possibility of relating certain ungrouped irons with major groups via multi-element, trace element modeling. In a companion abstract, the isotopic and trace element systematics of the ungrouped iron Tishomingo are compared with the IVB irons.

  7. Benchmark ab initio study of heavy-and superheavy-element systems A.V. Titov,

    E-print Network

    Titov, Anatoly

    Benchmark ab initio study of heavy- and superheavy-element systems A.V. Titov, N.S. Mosyagin, A for very accurate investigation of electronic structure of heavy and superheavy elements as well in molecules and discovery of superheavy elements from "island of stability". Success in trapping and cooling

  8. Calculations of stopping powers of 100 eV-30 keV electrons in 31 elemental solids

    NASA Astrophysics Data System (ADS)

    Tanuma, S.; Powell, C. J.; Penn, D. R.

    2008-03-01

    We present calculated electron stopping powers (SPs) for 31 elemental solids (Li, Be, glassy C, graphite, diamond, Na, Mg, K, Sc, Ti, V, Fe, Y, Zr, Nb, Mo, Ru, Rh, In, Sn, Cs, Gd, Tb, Dy, Hf, Ta, W, Re, Os, Ir, and Bi). These SPs were determined with an algorithm previously used for the calculation of electron inelastic mean free paths and from energy-loss functions (ELFs) derived from experimental optical data. The SP calculations were made for electron energies between 100eV and 30keV and supplement our earlier SP calculations for ten additional solids (Al, Si, Cr, Ni, Cu, Ge, Pd, Ag, Pt, and Au). Plots of SP versus atomic number for the group of 41 solids show clear trends. Multiple peaks and shoulders are seen that result from the contributions of valence-electron and various inner-shell excitations. Satisfactory agreement was found between the calculated SPs and values from the relativistic Bethe SP equation with recommended values of the mean excitation energy (MEE) for energies above 10keV. We determined effective MEEs versus maximum excitation energy from the ELFs for each solid. Plots of effective MEE versus atomic number showed the relative contributions of valence-electron and different core-electron excitations to the MEE. For a maximum excitation energy of 30keV, our effective MEEs agreed well for Be, graphite, Na, Al, and Si with recommended MEEs; a difference for Li was attributed to sample oxidation in the SP measurements for the recommended MEE. Substantially different effective MEEs were found for the three carbon allotropes (graphite, diamond, and glassy C).

  9. Molecular Evolution of P Transposable Elements in the Genus Drosophila. II. The obscura Species Group

    Microsoft Academic Search

    Javier García-Planells; Nuria Paricio; Jonathan B. Clark; Rosa de Frutos; Margaret G. Kidwell

    1998-01-01

    .   A phylogenetic analysis of P transposable elements in the Drosophila obscura species group is described. Multiple P sequences from each of 10 species were obtained using PCR primers that flank a conserved region of exon 2 of the transposase\\u000a gene. In general, the P element phylogeny is congruent with the species phylogeny, indicating that the dominant mode of transmission

  10. Verification of Tersoff's Potential for Static Structural Analysis of Solids of Group-IV Elements

    Microsoft Academic Search

    Koji Moriguchi; Akira Shintani

    1998-01-01

    We have carried out several stringent tests of Tersoff's potential through static structural analysis of solids of group-IV elements and examined the chemical properties of the Tersoff's potential for C, Si and Ge. It is clear that Tersoff's potential has a limited ability to describe the differences in chemical reactivity between elemental Ge and Si, but well describes the chemical

  11. Platinum group elements in the environment: emissions and exposure.

    PubMed

    Dubiella-Jackowska, Aleksandra; Polkowska, Zaneta; Namie?nik, Jacek

    2009-01-01

    PGEs (Pt, Pd, Ru, Ir, and Os) are a relatively new group of anthropogenic pollutants. Specific useful properties of these metals (high resistance to chemical corrosion over a wide range of temperatures, high melting point, high mechanical resistance, and high plasticity) have fomented rapid growth of new and existing applications in various economic and industrial sectors. These metals are not only used in the chemical, petrochemical, electrical, and electronics industries but also PGE use, in various industries, has dramatically increased emissions of these metals to the environment; emissions from vehicle catalytic converters and hospital wastewater discharges are particularly significant. The environmental benefits of using PGEs in vehicle catalytic converters are clear. These metals catalyze the conversion of toxic constituents of exhaust fumes (CO, HCs, NOxs) to water, CO2, and molecular nitrogen. As a result of adverse physico-chemical and mechanical influences on the catalyst surface, PGEs are released from this layer and are emitted into the environment in exhaust fumes. Research results indicate that the levels of such emissions are rather low (ng km(-1)). However, recent data show that certain chemical forms of PGEs emitted from vehicles are, or may be, bioavailable. Hence, the potential for PGEs to bioaccumulate in different environmental compartments should be studied, and, if necessary, addressed. The use of Pt in anticancerous drug preparations also contributes to environmental burdens. Pt, when administered as a drug, is excreted in a patient's urine and, as a consequence, has been observed in hospital and communal wastewater discharges. Few studies have been published that address bioavailability, mode of penetration into live organisms, or environmental fate of PGEs. The toxic effect of these metals on living organisms, including humans, is still in dispute and incompletely elucidated. Contrary to some chlorine complexes of Pt, which most frequently cause allergic reactions, the metallic forms of PGEs are probably inert; however, they may undergo transformation to biologically available forms after release to the environment. Because exposure to PGEs may result in health hazards, it is necessary to evaluate the risks of human exposure to these metals. Available data show that the highest exposed groups (Leceniewska et al. 2001) are individuals who work in refineries, chemical plants, electronics plants, jewelry production, oncological wards (medical personnel), and road maintenance; also highly exposed are women who have silicone breast implants. The effects of PGE exposure in live organisms include the following: asthma, miscarriage, nausea, hair loss, skin diseases, and, in humans, other serious health problems. As production and use of PGEs grow, there is a commensurate need to generate additional experimental and modeling data on them; such data would be designed to provide a better understanding of the environmental disposition and influence on human health of the PGEs. PMID:19110940

  12. On silicon group elements ejected by supernovae type IA

    SciTech Connect

    De, Soma; Timmes, F. X. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Brown, Edward F. [Joint Institute for Nuclear Astrophysics, University of Notre Dame, IN 46556 (United States); Calder, Alan C. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY (United States); Townsley, Dean M. [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL (United States); Athanassiadou, Themis [Swiss National Supercomputing Centre, Via Trevano 131, 6900 Lugano (Switzerland); Chamulak, David A. [Physics Division, Argonne National Laboratory, Argonne, IL (United States); Hawley, Wendy [Laboratoire d'Astrophysique de Marseille, Marseille cedex 13 F-13388 (France); Jack, Dennis, E-mail: somad@asu.edu [Departamento de Astronomía, Universidad de Guanajuato, Apartado Postal 144, 36000 Guanajuato (Mexico)

    2014-06-01

    There is evidence that the peak brightness of a Type Ia supernova is affected by the electron fraction Y {sub e} at the time of the explosion. The electron fraction is set by the aboriginal composition of the white dwarf and the reactions that occur during the pre-explosive convective burning. To date, determining the makeup of the white dwarf progenitor has relied on indirect proxies, such as the average metallicity of the host stellar population. In this paper, we present analytical calculations supporting the idea that the electron fraction of the progenitor systematically influences the nucleosynthesis of silicon group ejecta in Type Ia supernovae. In particular, we suggest the abundances generated in quasi-nuclear statistical equilibrium are preserved during the subsequent freeze-out. This allows potential recovery of Y {sub e} at explosion from the abundances recovered from an observed spectra. We show that measurement of {sup 28}Si, {sup 32}S, {sup 40}Ca, and {sup 54}Fe abundances can be used to construct Y {sub e} in the silicon-rich regions of the supernovae. If these four abundances are determined exactly, they are sufficient to recover Y {sub e} to 6%. This is because these isotopes dominate the composition of silicon-rich material and iron-rich material in quasi-nuclear statistical equilibrium. Analytical analysis shows the {sup 28}Si abundance is insensitive to Y {sub e}, the {sup 32}S abundance has a nearly linear trend with Y {sub e}, and the {sup 40}Ca abundance has a nearly quadratic trend with Y {sub e}. We verify these trends with post-processing of one-dimensional models and show that these trends are reflected in the model's synthetic spectra.

  13. Distribution of platinum group elements and other traffic related elements among different plants along some highways in Germany.

    PubMed

    Djingova, Rumiana; Kovacheva, Petya; Wagner, Gerhard; Markert, Bernd

    2003-06-01

    Using ICP-MS and ICP-AES platinum group elements (Pt, Pd, Rh, Ru and Ir) and Ce, La, Nd, Pb and Zr have been determined in street dust, Taraxacum officinale (dandelion), Plantago lanceolata (plantain), Lolium multiflorum (annual ryegrass), Rhytidiadelphus squarrosus (moss) and Vascellum pratense (mushrooms) collected along highways and streets in Germany during 1999. Among the plants Taraxacum officinale (dandelion) reflects most adequately the pollution with the investigated elements matching the results from street dust. A strong positive correlation between all elements determined in the plants is established. Transfer factor for Pt between soil and plants has been determined in an agricultural experiment ranging between 0.004 and 0.008 for two types of soils. PMID:12738216

  14. Clostridium botulinum group III: a group with dual identity shaped by plasmids, phages and mobile elements

    Microsoft Academic Search

    Hanna Skarin; Therese Håfström; Josefina Westerberg; Bo Segerman

    2011-01-01

    Background  \\u000a Clostridium botulinum strains can be divided into four physiological groups that are sufficiently diverged to be considered as separate species.\\u000a Here we present the first complete genome of a C. botulinum strain from physiological group III, causing animal botulism. We also compare the sequence to three new draft genomes from\\u000a the same physiological group.\\u000a \\u000a \\u000a \\u000a \\u000a Results  The 2.77 Mb chromosome was

  15. Analysis of the trace element content of coals from the Wabaunsee Group southeastern Nebraska

    SciTech Connect

    Kaplan, S.S.; Carr, J.D.; Kelter, P.B.

    1983-01-01

    Eight coal samples obtained from the Honey Creek, Lorton, Wamego, Elmo, and Nodaway coals of the Wabaunsee Group (Upper Pennsylvanian) were analyzed for their concentration of certain trace elements. Analysis of the data suggests (a) a general decrease of trace element concentrations away from the Precambrian Nemaha Arch in a basinward direction, and (b) the post-diagenetic emplacement of lead, zinc and cadmium typical of mid-continent coals.

  16. 3D finite element analysis on pile-soil interaction of passive pile group

    Microsoft Academic Search

    Ming-hua Zhao; Dun-ping Liu; Ling Zhang; Chong Jiang

    2008-01-01

    The interaction between pile and soft soil of the passive pile group subjected to soil movement was analyzed with three-dimensional\\u000a finite element model by using ANSYS software. The soil was assumed to be elastic-plastic complying with the Drucker-Prager\\u000a yield criterion in the analysis. The large displacement of soil was considered and contact elements were used to evaluate\\u000a the interaction between

  17. sp3-hybridized framework structure of group-14 elements discovered by genetic algorithm

    SciTech Connect

    Nguyen, Manh Cuong [Ames Laboratory; Zhao, Xin [Ames Laboratory; Wang, Cai-Zhuang [Ames Laboratory; Ho, Kai-Ming [Ames Laboratory

    2014-05-01

    Group-14 elements, including C, Si, Ge, and Sn, can form various stable and metastable structures. Finding new metastable structures of group-14 elements with desirable physical properties for new technological applications has attracted a lot of interest. Using a genetic algorithm, we discovered a new low-energy metastable distorted sp3-hybridized framework structure of the group-14 elements. It has P42/mnm symmetry with 12 atoms per unit cell. The void volume of this structure is as large as 139.7Å3 for Si P42/mnm, and it can be used for gas or metal-atom encapsulation. Band-structure calculations show that P42/mnm structures of Si and Ge are semiconducting with energy band gaps close to the optimal values for optoelectronic or photovoltaic applications. With metal-atom encapsulation, the P42/mnm structure would also be a candidate for rattling-mediated superconducting or used as thermoelectric materials.

  18. The nuclear organization of Polycomb\\/Trithorax group response elements in larval tissues of Drosophila melanogaster

    Microsoft Academic Search

    Elena Fedorova; Nicolas Sadoni; Ina K. Dahlsveen; Jeannette Koch; Elisabeth Kremmer; Dirk Eick; Renato Paro; Daniele Zink

    2008-01-01

    We analysed the nuclear organization of the Polycomb\\/Trithorax group response element (PRE\\/TRE) Fab-7 and of other PRE\\/TREs\\u000a in larval tissues of D. melanogaster. The results show that pairing\\/clustering of transgenic and endogenous Fab-7 elements and of other endogenous PRE\\/TREs occurs\\u000a only to a limited degree in a highly locus-specific and tissue-specific manner. However, transgenic Fab-7 elements as well\\u000a as the

  19. Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2009

    USGS Publications Warehouse

    Archinal, B.A.; A'Hearn, M.F.; Bowell, E.; Conrad, A.; Consolmagno, G.J.; Courtin, R.; Fukushima, T.; Hestroffer, D.; Hilton, J.L.; Krasinsky, G.A.; Neumann, G.; Oberst, J.; Seidelmann, P.K.; Stooke, P.; Tholen, D.J.; Thomas, P.C.; Williams, I.P.

    2011-01-01

    Every three years the IAU Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report takes into account the IAU Working Group for Planetary System Nomenclature (WGPSN) and the IAU Committee on Small Body Nomenclature (CSBN) definition of dwarf planets, introduces improved values for the pole and rotation rate of Mercury, returns the rotation rate of Jupiter to a previous value, introduces improved values for the rotation of five satellites of Saturn, and adds the equatorial radius of the Sun for comparison. It also adds or updates size and shape information for the Earth, Mars' satellites Deimos and Phobos, the four Galilean satellites of Jupiter, and 22 satellites of Saturn. Pole, rotation, and size information has been added for the asteroids (21) Lutetia, (511) Davida, and (2867) ??teins. Pole and rotation information has been added for (2) Pallas and (21) Lutetia. Pole and rotation and mean radius information has been added for (1) Ceres. Pole information has been updated for (4) Vesta. The high precision realization for the pole and rotation rate of the Moon is updated. Alternative orientation models for Mars, Jupiter, and Saturn are noted. The Working Group also reaffirms that once an observable feature at a defined longitude is chosen, a longitude definition origin should not change except under unusual circumstances. It is also noted that alternative coordinate systems may exist for various (e. g. dynamical) purposes, but specific cartographic coordinate system information continues to be recommended for each body. The Working Group elaborates on its purpose, and also announces its plans to occasionally provide limited updates to its recommendations via its website, in order to address community needs for some updates more often than every 3 years. Brief recommendations are also made to the general planetary community regarding the need for controlled products, and improved or consensus rotation models for Mars, Jupiter, and Saturn. ?? 2010 Springer Science+Business Media B.V.(outside the USA).

  20. Functional groups and elemental analyses of cuticular morphotypes of Cordaites principalis (Germar) Geinitz, Carboniferous Maritimes Basin, Canada

    USGS Publications Warehouse

    Zodrow, E.L.; Mastalerz, Maria; Orem, W.H.; Simunek, Z.; Bashforth, A.R.

    2000-01-01

    Well-preserved cuticles were isolated from Cordaites principalis (Germar) Geinitz leaf compressions, i.e., foliage from extinct gymnosperm trees Coniferophyta: Order Cordaitales. The specimens were collected from the Sydney. Stellarton and Bay St. George subbasins of the once extensive Carboniferous Maritimes Basin of Atlantic Canada. Fourier transformation of infrared spectra (FTIR) and elemental analyses indicate that the ca. 300-306-million-year-old fossil cuticles share many of the functional groups observed in modern cuticles. The similarities of the functional groups in each of the three cuticular morphotypes studied support the inclusion into a single cordaite-leaf taxon, i.e., C. principalis (Germar), confirming previous morphological investigations. Vitrinite reflectance measurements on coal seams in close proximity to the fossil-bearing sediments reveal that the Bay St. George sample site has the lowest thermal maturity, whereas the sites in Sydney and Stellarton are more mature. IR absorption and elemental analyses of the cordaite compressions corroborate this trend, which suggests that the coalified mesophyll in the leaves follows a maturation path similar to that of vitrinite. Comparison of functional groups of the cordaite cuticles with those from certain pteridosperms previously studied from the Sydney Subbasin shows that in the cordaite cuticles highly conjugated C-O (1632 cm-1) bands dominate over carbonyl stretch that characterizes the pteridosperm cuticles. The differences demonstrate the potential of chemotaxonomy as a valuable tool to assist distinguishing between Carboniferous plant-fossil groups. Published by Elsevier Science B.V.

  1. Intermediate Phases, structural variance and network demixing in chalcogenides: the unusual case of group V sulfides

    E-print Network

    P. Boolchand; Ping Chen; U. Vempati

    2008-10-20

    We review Intermediate Phases (IPs) in chalcogenide glasses and provide a structural interpretation of these phases. In binary group IV selenides, IPs reside in the 2.40 sulfides exhibit IPs that are shifted to even a lower r than their selenide counterparts; a result that we trace to excess Sn chains either partially (As-S) or completely (P-S) demixing from network backbone, in contrast to excess Sen chains forming part of the backbone in corresponding selenide glasses. In ternary chalcogenides of Ge with the group V elements (As, P), IPs of the sulfides are similar to their selenide counterparts, suggesting that presence of Ge serves to reign in the excess Sn chain fragments back in the backbone as in their selenide counterparts.

  2. Conserved Structural Elements in the V3 Crown of HIV-1 gp120

    SciTech Connect

    Jiang, X.; Burke, V; Totrov, M; Williams, C; Cardozo, T; Gorny, M; Zolla-Pazner, S; Kong, X

    2010-01-01

    Binding of the third variable region (V3) of the HIV-1 envelope glycoprotein gp120 to the cell-surface coreceptors CCR5 or CXCR4 during viral entry suggests that there are conserved structural elements in this sequence-variable region. These conserved elements could serve as epitopes to be targeted by a vaccine against HIV-1. Here we perform a systematic structural analysis of representative human anti-V3 monoclonal antibodies in complex with V3 peptides, revealing that the crown of V3 has four conserved structural elements: an arch, a band, a hydrophobic core and the peptide backbone. These are either unaffected by or are subject to minimal sequence variation. As these regions are targeted by cross-clade neutralizing human antibodies, they provide a blueprint for the design of vaccine immunogens that could elicit broadly cross-reactive protective antibodies.

  3. Platinum group elements in raptor eggs, faeces, blood, liver and kidney

    Microsoft Academic Search

    Kristine H. Ek; Sebastien Rauch; Gregory M. Morrison; Peter Lindberg

    2004-01-01

    The increased use of platinum group elements (PGEs) in automobile catalysts and their emission into the environment has led to a concern over environmental and particularly biological accumulation. Specimens of samples from raptors are useful for the investigation of the impact of PGEs because these birds are found in both urban and rural environments and are invariably at the top

  4. Sources of rare earth elements in Appin Group limestones, Dalradian, north-east Scotland

    Microsoft Academic Search

    C. W. Thomas

    1993-01-01

    Summary Rare earth elements (REE) have been determined in 15 samples from three metamorphosed limestone units of the Appin Group of the Dalradian of north-east Scotland. Total REE contents range from about 7 to about 50 ppm and the light REEs are slightly enriched compared with REE in the North American Shale Composite (NASC). In the more impure limestones, the

  5. Traffic-related platinum group elements (PGE) in soils from Mexico City

    Microsoft Academic Search

    Ofelia Morton; Harald Puchelt; Elizabeth Hernández; Elena Lounejeva

    2001-01-01

    The first evaluation of the distribution of platinum group elements (PGE) derived from automobile catalytic converters in urban soil samples in Mexico City was carried out. There are more than four millions cars in Mexico City and, at the present time, one third of them have catalytic converters. PGE concentrations in soils exposed to high traffic densities exceed the natural

  6. Methods for the determination of platinum group elements originating from the abrasion of automotive catalytic converters

    Microsoft Academic Search

    László Bencs; Khaiwal Ravindra; René Van Grieken

    2003-01-01

    Anthropogenic emission of platinum group elements (PGEs) from the abrasion of automotive catalytic converters into the environment has significantly increased. However, the concentration level of these PGEs (i.e. Pd, Pt, Rh) is still very low in the nature. Accordingly, their determination and speciation in various environmental compartments appears to be a challenging task for analytical chemists. The present review gives

  7. Research paper Os decay system applied to dating platinum-group element

    E-print Network

    Reiners, Peter W.

    Research paper The 190 Pt­186 Os decay system applied to dating platinum-group element and economic significance the intrusion has been widely and intensely studied, with a large body of research mass spectrometry (LA-MC- ICPMS), has recently bee

  8. Theoretical study of the bonding between aminocarbene and main group elements

    E-print Network

    Paris-Sud XI, Université de

    Theoretical study of the bonding between aminocarbene and main group elements Gilles Frison CH2, SiH2, NH, PH, O or S. The bonding mode has been described using the Natural Bond Orbital (NBO Localization Function (ELF). A donor­acceptor interaction with a substantial back- bonding of the carbenoid

  9. Methods for the Determination of Platinum Group Elements in Environmental and Biological Materials: A Review

    Microsoft Academic Search

    Maria Balcerzak

    2011-01-01

    Automobile catalysts are major anthropogenic sources of ultra-traces of platinum group elements (PGEs) in the environment. Nanoparticles of platinum, palladium, and rhodium, the active components of autocatalysts, are being spread into the environment during vehicle operation. Bioaccumulation of the metals can lead to their elevated levels in living organisms. The evaluation of the health risk from PGEs requires the investigation

  10. Platinum Group Elements Enhance the Allergic Immune Response by Acting on Dendritic Cells

    Microsoft Academic Search

    Clara Paolucci; Jessica Ponti; Monica V. Fabbri; Daniela Breda; Enrico Sabbioni; Samuele E. Burastero

    2007-01-01

    Background: Atmospheric pollution may play a role in the immune response to allergens either directly or by entering the food chain. While particulate platinum group elements (PLGE) emitted by catalytic converters can be considered biologically inert, approximately 10% of these species accumulate in the environment as bioavailable soluble forms. Methods: We challenged in vitro human immature and mature monocyte-derived dendritic

  11. Mobility of rhenium, platinum group elements and organic carbon during black shale weathering

    Microsoft Academic Search

    Lillie A Jaffe; Bernhard Peucker-Ehrenbrink; Steven T Petsch

    2002-01-01

    This study investigates the effects of black shale weathering on the Re–Os isotope system, platinum group element concentrations and the degradation of organic matter. Samples from a weathering profile in Late Devonian (?365 Myr) Ohio Shale show a pronounced decrease (?77%) in organic carbon (Corg) near the present soil surface, relative to the interior portion of the outcrop. A similar

  12. Trace-element composition and zoning in clinopyroxene- and amphibole-group minerals: Implications for element partitioning and evolution of carbonatites

    NASA Astrophysics Data System (ADS)

    Reguir, Ekaterina P.; Chakhmouradian, Anton R.; Pisiak, Laura; Halden, Norman M.; Yang, Panseok; Xu, Cheng; Kynický, Jind?ich; Couëslan, Chris G.

    2012-01-01

    The present work is a first comprehensive study of the trace-element composition and zoning in clinopyroxene- and amphibole-group minerals from carbonatites, incorporating samples from 14 localities worldwide (Afrikanda, Aley, Alnö, Blue River, Eden Lake, Huayangchuan, Murun, Oka, Ozernaya Varaka, Ozernyi, Paint Lake, Pinghe, Prairie Lake, Turiy Mys). The new electron-microprobe data presented here significantly extend the known compositional range of clinopyroxenes and amphiboles from carbonatites. These data confirm that calcic and sodic clinopyroxenes from carbonatites are not separated by a compositional gap, instead forming an arcuate trend from nearly pure diopside through intermediate aegirine-augite compositions confined to a limited range of CaFeSi 2O 6 contents (15-45 mol%) to aegirine with < 25 mol% of CaMgSi 2O 6 and a negligible proportion of CaFeSi 2O 6. A large set of LA-ICPMS data shows that the clinopyroxenes of different composition are characterized by relatively low levels of Cr, Co and Ni (? 40 ppm) and manifold variations in the concentration of trivalent lithophile and some incompatible elements (1-150 ppm Sc, 26-6870 ppm V, 5-550 ppm Sr, 90-2360 ppm Zr, and nil to 150 ppm REE), recorded in some cases within a single crystal. The relative contribution of clinopyroxenes to the whole-rock Rb, Nb, Ta, Th and U budget is negligible. The major-element compositional range of amphiboles spans from alkali- and Al-poor members (tremolite) to Na-Al-rich Mg- or, less commonly, Fe-dominant members (magnesiohastingsite, hastingsite and pargasite), to calcic-sodic, sodic and potassic-sodic compositions intermediate between magnesio-ferrikatophorite, richterite, magnesioriebeckite, ferri-nyböite and (potassic-)magnesio-arfvedsonite. In comparison with the clinopyroxenes, the amphiboles contain similar levels of tetravalent high-field-strength elements (Ti, Zr and Hf) and compatible transition elements (Cr, Co and Ni), but are capable of incorporating much higher concentrations of Sc and incompatible elements (up to 500 ppm Sc, 43 ppm Rb, 1470 ppm Sr, 1230 ppm Ba, 80 ppm Pb, 1070 ppm REE, 140 ppm Y, and 180 ppm Nb). In some carbonatites, amphiboles contribute as much as 25% of the Zr + Hf, 15% of the Sr and 35% of the Rb + Ba whole-rock budget. Both clinopyroxenes and amphiboles may also host a significant share (~ 10%) of the bulk heavy-REE content. Our trace-element data show that the partitioning of REE between clinopyroxene (and, in some samples, amphibole) and the melt is clearly bimodal and requires a revision of the existing models assuming single-site REE partitioning. Clinopyroxenes and amphiboles from carbonatites exhibit a diversity of zoning patterns that cannot be explained exclusively on the basis of crystal chemistry and relative compatibility of different trace-element in these minerals. Paragenetic analysis indicates that in most cases, the observed zoning patterns develop in response to removal of selected trace elements by phases co-precipitating with clinopyroxene and amphibole (especially magnetite, fluorapatite, phlogopite and pyrochlore). With the exception of magnesiohastingsite-richterite sample from Afrikanda, the invariability of trace-element ratios in the majority of zoned clinopyroxene and amphibole crystals implies that fluids are not involved in the development of zoning in these minerals. The implications of the new trace-element data for mineral exploration targeting REE, Nb and other types of carbonatite-hosted rare-metal mineralization are discussed.

  13. Conservation of CD44 exon v3 functional elements in mammals

    PubMed Central

    Vela, Elena; Hilari, Josep M; Delclaux, María; Fernández-Bellon, Hugo; Isamat, Marcos

    2008-01-01

    Background The human CD44 gene contains 10 variable exons (v1 to v10) that can be alternatively spliced to generate hundreds of different CD44 protein isoforms. Human CD44 variable exon v3 inclusion in the final mRNA depends on a multisite bipartite splicing enhancer located within the exon itself, which we have recently described, and provides the protein domain responsible for growth factor binding to CD44. Findings We have analyzed the sequence of CD44v3 in 95 mammalian species to report high conservation levels for both its splicing regulatory elements (the 3' splice site and the exonic splicing enhancer), and the functional glycosaminglycan binding site coded by v3. We also report the functional expression of CD44v3 isoforms in peripheral blood cells of different mammalian taxa with both consensus and variant v3 sequences. Conclusion CD44v3 mammalian sequences maintain all functional splicing regulatory elements as well as the GAG binding site with the same relative positions and sequence identity previously described during alternative splicing of human CD44. The sequence within the GAG attachment site, which in turn contains the Y motif of the exonic splicing enhancer, is more conserved relative to the rest of exon. Amplification of CD44v3 sequence from mammalian species but not from birds, fish or reptiles, may lead to classify CD44v3 as an exclusive mammalian gene trait. PMID:18710510

  14. 20 CFR 655.1115 - Element V-What does “no strike/lockout or layoff” mean?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Element V-What does âno strike/lockout or layoffâ...as Registered Nurses? § 655.1115 Element V—What does “no strike/lockout or layoff” mean? (a) The fifth attestation element requires that the facility...

  15. Cations and dications of heavier group 14 elements in low oxidation states.

    PubMed

    Swamy, V S V S N; Pal, Shiv; Khan, Shabana; Sen, Sakya S

    2015-07-14

    Cations and dications of heavier group 14 elements in their low oxidation state have received widespread attention in recent years. The journey started with the isolation of a series of cations of the composition [(C5Me5)E:](+) [E = Si-Pb], followed by the more recent isolation of a Ge(ii) dication encapsulated within a cryptand, a carbodiphosphorane stabilized [GeCl](+) monocation with a two coordinate Ge atom, Si(ii) cations and dications stabilized by N-heterocyclic carbenes (NHCs), which highlights the ongoing growth and interest in the chemistry of tetrel(ii) cations. This is presumably because the central atom (E) in these compounds contains two or three unoccupied valence orbitals as well as holds a lone pair of electrons. Such an electronic description represents ambiphilicity, which is of great interest for catalysis. The successful synthesis of divalent group 14 cations requires new synthetic strategies based on the sterically demanding neutral or monoanionic ligands, utilization of counter anions, and solvents with low nucleophilicity in order to minimize the degree of interactions with the cations. An alternative approach for the realization of divalent cations of group 14 elements is their coordination to the transition metals. This synthetic approach was successfully applied for the isolation of a range of transition metal coordinated divalent cations of group 14 elements. Apart from arousing academic interest some of these cations have found application as activators in the Ziegler-Natta polymerization of alkenes. PMID:26084389

  16. 33 CFR 155.5052 - Response plan development and evaluation criteria for nontank vessels carrying group V petroleum...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...for nontank vessels carrying group V petroleum oil. 155.5052 Section 155...for nontank vessels carrying group V petroleum oil. Owners or operators of nontank vessels that carry group V petroleum oil as fuel or cargo must meet...

  17. Adhesion and friction behavior of group 4 elements germanium, silicon, tin, and lead

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1975-01-01

    Adhesion and friction studies were conducted with thin films of the group IV elements silicon, germanium, tin, and lead ion plated on the nickel (011) substrate. The mating surface was gold (111). Contacts were made for the elements in the clean state and with oxygen present. Adhesion and friction experiments were conducted at very light loads of 1 to 10 g. Sliding was at a speed of 0.7 mm/min. Friction results indicate that the more covalently bonded elements silicon and germanium exhibit lower adhesion and friction than the more metallic bonded tin and lead. The adhesion of gold to germanium was observed, and recrystallization of the transferred gold occurred. Plastic flow of germanium was seen with sliding. Oxygen reduced, but did not eliminate, the adhesion observed with germanium and silicon.

  18. Report of the IAU\\/IAG Working Group on cartographic coordinates and rotational elements: 2006

    Microsoft Academic Search

    P. Kenneth Seidelmann; B. A. Archinal; M. F. A’hearn; A. Conrad; G. J. Consolmagno; D. Hestroffer; J. L. Hilton; G. A. Krasinsky; G. Neumann; J. Oberst; P. Stooke; E. F. Tedesco; D. J. Tholen; P. C. Thomas; I. P. Williams

    2007-01-01

    Every three years the IAU\\/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the\\u000a directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report\\u000a introduces improved values for the pole and rotation rate of Pluto, Charon, and Phoebe, the pole of Jupiter, the sizes and\\u000a shapes of

  19. Electron transport study of single wall nanotubes based on group 14 elements

    NASA Astrophysics Data System (ADS)

    Sivasathya, S.; Thiruvadigal, D. John

    2012-06-01

    By applying non-equilibrium Green's functions in combination with density functional theory, we investigate the transport behaviours of single wall nanotubes based on group14 elements. The transmission spectrum and density of states for single wall nanotubes such as Lead nanotube(PbNT), Germanium nanotube(GeNT), Silicon nanotube(SiNT), Tin nanotube(SnNT) and Carbon nanotube(CNT) are compared.

  20. 0v{beta}{beta} decay: theoretical nuclear matrix elements and their covariances

    SciTech Connect

    Lisi, Eligio [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Via Orabona 4, 70126 Bari (Italy)

    2009-11-09

    Within the quasiparticle random phase approximation (QRPA), the covariances associated to the nuclear matrix elements (NME) of neutrinoless double beta decay (0v{beta}{beta}) are estimated. It is shown that correlated NME uncertainties play an important role in the comparison of 0v{beta}{beta} decay rates for different nuclei, both in the standard case of light Majorana neutrino exchange, and in nonstandard physics cases.

  1. A triangular v. Kármán type finite element for sandwich plates with transversely compressible core

    Microsoft Academic Search

    Serkan Demiray; Wilfried Becker; Jörg Hohe

    2004-01-01

    The present study is concerned with a new higher-order finite element for sandwich plates with transversely compressible core. The underlying plate theory is of the multilayer type, where the standard Kirchhoff–Love hypothesis is adopted for the face sheets whereas a second order displacement expansion is used for the core. Geometrical nonlinearities are included in the v. Kármán sense. Based on

  2. Rhenium–osmium isotope and platinum-group elements in the Xinjie layered intrusion, SW China: Implications for source mantle composition, mantle evolution, PGE fractionation and mineralization

    Microsoft Academic Search

    Hong Zhong; Liang Qi; Rui-Zhong Hu; Mei-Fu Zhou; Ti-Zhong Gou; Wei-Guang Zhu; Bing-Guang Liu; Zhu-Yin Chu

    2011-01-01

    The Xinjie mafic–ultramafic layered intrusion in the Emeishan large igneous province (ELIP) hosts Cu–Ni–platinum group element (PGE) sulfide ore layers within the lower part and Fe–Ti–V oxide-bearing horizons within the middle part. The major magmatic Cu–Ni–PGE sulfide ores and spatially associated cumulate rocks are examined for their PGE contents and Re–Os isotopic systematics. The samples yielded a Re–Os isochron with

  3. Partitioning of Si and platinum group elements between liquid and solid Fe-Si alloys

    NASA Astrophysics Data System (ADS)

    Morard, G.; Siebert, J.; Badro, J.

    2014-05-01

    Crystallization of the Earth's inner core fractionates major and minor elements between the solid and liquid metal, leaving physical and geochemical imprints on the Earth's core. For example, the density jump observed at the Inner Core Boundary (ICB) is related to the preferential partitioning of lighter elements in the liquid outer core. The fractionation of Os, Re and Pt between liquid and solid during inner core crystallization has been invoked as a process that explains the observed Os isotopic signature of mantle plume-derived lavas (Brandon et al., 1998; Brandon and Walker, 2005) in terms of core-mantle interaction. In this article we measured partitioning of Si, Os, Re and Pt between liquid and solid metal. Isobaric (2 GPa) experiments were conducted in a piston-cylinder press at temperatures between 1250 °C and 1600 °C in which an imposed thermal gradient through the sample provided solid-liquid coexistence in the Fe-Si system. We determined the narrow melting loop in the Fe-Si system using Si partitioning values and showed that order-disorder transition in the Fe-Si solid phases can have a large effect on Si partitioning. We also found constant partition coefficients (DOs, DPt, DRe) between liquid and solid metal, for Si concentrations ranging from 2 to 12 wt%. The compact structure of Fe-Si liquid alloys is compatible with incorporation of Si and platinum group elements (PGEs) elements precluding solid-liquid fractionation. Such phase diagram properties are relevant for other light elements such as S and C at high pressure and is not consistent with inter-elemental fractionation of PGEs during metal crystallization at Earth's inner core conditions. We therefore propose that the peculiar Os isotopic signature observed in plume-derived lavas is more likely explained by mantle source heterogeneity (Meibom et al., 2002; Baker and Krogh Jensen, 2004; Luguet et al., 2008).

  4. Gene transfer directly demonstrates a role for TCR V alpha elements in superantigen recognition.

    PubMed

    Donson, D; Borrero, H; Rutman, M; Pergolizzi, R; Malhado, N; Macphail, S

    1997-06-01

    Recent structure-function studies of ours and others indicating that regions of the TCR other than V beta are involved in the TCR-superantigen (SAg)-MHC class II trimolecular interaction were correlative; thus, while the conclusions were persuasive, they were not unequivocal. The transfection experiments described in this report show that 1) responsiveness to staphylococcal enterotoxin B in V beta6 T cells was transferred by a V alpha4- but not by V alpha8- and V alpha10-containing alpha-chain cDNA constructs, 2) responsiveness was not transferred by a chimeric alpha-chain construct containing the N and J regions from a responsive T hybrid clone and the V alpha10 V alpha region from a nonresponsive clone, and 3) responsiveness was transferred by a chimeric alpha-chain construct in which most of the V alpha region (from the N terminus to the C-terminal end of the complementarity-determining region 2) was derived from the V alpha4 alpha-chain of a responsive T hybrid and the rest (framework 3, N, and J) from the V alpha8 alpha-chain of a nonresponsive T hybrid. Thus, these data provide the first direct evidence for a specific SAg response facilitating activity in a defined V alpha segment and map this activity N-terminal of framework region 3. Furthermore, the diversity in the alpha- and beta-chain junctional regions of a panel of staphylococcal enterotoxin B-responsive V beta6 T hybrid clones excludes a stringent corequirement for a particular junctional region for the V alpha4 segment to mediate its facilitating activity. Finally, a model postulating a universal role for V alpha elements in TCR recognition of SAg is presented. PMID:9164940

  5. Nonelastic-scattering cross sections of elemental nickel. [1. 3 to 4. 5 MeV

    SciTech Connect

    Smith, A.B.; Guenther, P.T.; Whalen, J.F.

    1980-06-01

    Neutron total cross sections of elemental nickel were measured from 1.3 to 4.5 MeV, at intervals of approx. 50 keV, with resolutions of 30 to 50 keV and to accuracies of 1 to 2.5%. Neutron differential-elastic-scattering cross sections were measured from 1.45 to 3.8 MeV, at intervals and with resolutions comparable to those of the total cross sections, and to accuracies of 3 to 5%. The nonelastic-scattering cross section is derived from the measured values to accuracies of greater than or equal to 6%. The experimental results are compared with previously reported values as represented by ENDF/B-V, and areas of consistency and discrepancy, noted. The measured results are shown to be in good agreement with the predictions of a model previously reported by the authors. 4 figures, 1 table.

  6. Multiple complexation of CO and related ligands to a main-group element.

    PubMed

    Braunschweig, Holger; Dewhurst, Rian D; Hupp, Florian; Nutz, Marco; Radacki, Krzysztof; Tate, Christopher W; Vargas, Alfredo; Ye, Qing

    2015-06-18

    The ability of an atom or molecular fragment to bind multiple carbon monoxide (CO) molecules to form multicarbonyl adducts is a fundamental trait of transition metals. Transition-metal carbonyl complexes are vital to industry, appear naturally in the active sites of a number of enzymes (such as hydrogenases), are promising therapeutic agents, and have even been observed in interstellar dust clouds. Despite the wealth of established transition-metal multicarbonyl complexes, no elements outside groups 4 to 12 of the periodic table have yet been shown to react directly with two or more CO units to form stable multicarbonyl adducts. Here we present the synthesis of a borylene dicarbonyl complex, the first multicarbonyl complex of a main-group element prepared using CO. The compound is additionally stable towards ambient air and moisture. The synthetic strategy used--liberation of a borylene ligand from a transition metal using donor ligands--is broadly applicable, leading to a number of unprecedented monovalent boron species with different Lewis basic groups. The similarity of these compounds to conventional transition-metal carbonyl complexes is demonstrated by photolytic liberation of CO and subsequent intramolecular carbon-carbon bond activation. PMID:26085273

  7. Mono- and polynucleation, atomistic growth, and crystal phase of III-V nanowires under varying group V flow

    NASA Astrophysics Data System (ADS)

    Dubrovskii, V. G.

    2015-05-01

    We present a refined model for the vapor-liquid-solid growth and crystal structure of Au-catalyzed III-V nanowires, which revisits several assumptions used so far and is capable of describing the transition from mononuclear to polynuclear regime and ultimately to regular atomistic growth. We construct the crystal phase diagrams and calculate the wurtzite percentages, elongation rates, critical sizes, and polynucleation thresholds of Au-catalyzed GaAs nanowires depending on the As flow. We find a non-monotonic dependence of the crystal phase on the group V flow, with the zincblende structure being preferred at low and high group V flows and the wurtzite structure forming at intermediate group V flows. This correlates with most of the available experimental data. Finally, we discuss the atomistic growth picture which yields zincblende crystal structure and should be very advantageous for fabrication of ternary III-V nanowires with well-controlled composition and heterointerfaces.

  8. Mono- and polynucleation, atomistic growth, and crystal phase of III-V nanowires under varying group V flow.

    PubMed

    Dubrovskii, V G

    2015-05-28

    We present a refined model for the vapor-liquid-solid growth and crystal structure of Au-catalyzed III-V nanowires, which revisits several assumptions used so far and is capable of describing the transition from mononuclear to polynuclear regime and ultimately to regular atomistic growth. We construct the crystal phase diagrams and calculate the wurtzite percentages, elongation rates, critical sizes, and polynucleation thresholds of Au-catalyzed GaAs nanowires depending on the As flow. We find a non-monotonic dependence of the crystal phase on the group V flow, with the zincblende structure being preferred at low and high group V flows and the wurtzite structure forming at intermediate group V flows. This correlates with most of the available experimental data. Finally, we discuss the atomistic growth picture which yields zincblende crystal structure and should be very advantageous for fabrication of ternary III-V nanowires with well-controlled composition and heterointerfaces. PMID:26026456

  9. The Origin and Distribution of Heavy Elements in the CD Groups MKW 4 and AWM 4

    NASA Technical Reports Server (NTRS)

    Vrtilek, Jan; Mushotzky, Richard (Technical Monitor)

    2003-01-01

    At this point, data for MKW4 have been received and those for AWM4 are still awaited. The MKW4 data have been fully analyzed and a complete manuscript is available and in final review by co-authors before submission for refereed publication. The following is a summary of our principal findings: We examined the distribution and properties of the hot gas which makes up the group halo. The inner halo shows some signs of structure, with circular or elliptical beta-models providing a poor fit to the surface brightness profile. This may be evidence of large-scale motion in the inner halo, but we do not find evidence of sharp fronts or edges in the emission. The temperature of the halo declines in the core, with deprojected spectral fits showing a central temperature of approximately 1.3keV compared to approximately 3keV at 250 arcsec. However, cooling flow models provide poor fits to the inner regions of the group and the estimated cooling time of the gas is long except within the central dominant galaxy, NGC4073. Abundance profiles show a sharp increase in the core of the group. We conclude that MKW4 is a fairly relaxed group, which has developed a strong central temperature gradient but not a large-scale cooling flow.

  10. pH-dependent release of trace elements including platinum group elements (PGEs) from gasoline and diesel catalysts

    NASA Astrophysics Data System (ADS)

    Sucha, Veronika; Mihaljevic, Martin; Ettler, Vojtech; Strnad, Ladislav

    2014-05-01

    The release of trace metals and platinum group elements (PGEs) from automobile exhaust catalysts represents a remarkable source of higly dispersed environmental contamination. Especially, PGEs have shown increasing research interest due to their possible bioaccessibility. In our research, we focused on leaching behaviour of trace metals from gasoline and diesel automobile catalysts. While catalysts for gasoline engines contain a mixture of Pt-Pd-Rh or Pd-Rh, catalysts for diesel engines are composed only of Pt. We used dust from two crushed gasoline and two crushed diesel catalysts (new and aged). The dust of gasoline catalysts contains significant concentrations of Pt (700 mg.kg-1), Pd (11 000 mg.kg-1) and Rh (700 mg.kg-1). And the dust of diesel catalysts are composed of Pt (3 900 mg.kg-1) and they contains negligible amounts of Pd dan Rh (< 0.5 mg.kg-1, < 0.1 mg.kg-1, respectively). To evaluate leaching of trace metals from dust we used pH-stat leaching test according to the European standard CEN/TS 14997. The concentrations of cations: PGEs (Pt, Pd a Rh), K, Na, Ca, Mg, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, La and Ce were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), and anions: F-, Cl-, SO42- and NO3- by high-performance liquid chromatography. Although the dusts from catalysts were relatively stable to acid/base influence, the leaching of trace metals from catalysts showed a dependence on pH. Generally, the highest concentrations were released under acidic conditions. The leaching of PGEs was higher for Pt in diesel catalysts and for Pd and Rh in gasoline catalysts. The highest concentrations of Zn and Pb were observed in old catalysts. The rare earth metals were released more from gasoline catalysts. Catalysts particles represent health risk especially with respect to their PGEs contents.

  11. Metallic phases and siderophile elements in main group ureilites: Implications for ureilite petrogenesis

    NASA Astrophysics Data System (ADS)

    Goodrich, Cyrena A.; Ash, Richard D.; Van Orman, James A.; Domanik, Kenneth; McDonough, William F.

    2013-07-01

    Metallic phases and siderophile elements are critical to understanding the petrogenesis of the enigmatic ureilite meteorites. We obtained petrographic, major and minor element, and the first in situ trace element data for metallic phases (metal, sulfides, phosphide, carbide) in 24 main group ureilites of various petrographic types with Fo ˜75-95. The most abundant type of metal (˜1-3 vol.%) occurs as ˜10-40 ?m-wide strips along silicate grain boundaries. Ni contents of this metal range from ˜0 to 7.3 wt.% and are correlated with Co among all samples (Ni/Co = 0.64 × CI). A less abundant type of metal occurs as ˜5-150 ?m diameter metallic spherules, consisting of cohenite (Fe3C), metal, phosphide and sulfide, enclosed in silicates (preferentially low-Ca pyroxene). Most samples contain 2 types of sulfide: (1) low-Cr (<0.1 wt.%) troilite, and (2) lamellar intergrowths of daubreelite (FeCr2S4) and troilite. Abundances of 17 (mostly siderophile) elements were measured by LA-ICP-MS in grain boundary metal, spherules, graphite, sulfides and silicates. Average compositions of grain boundary metal in 10 samples show decreasing CI-normalized abundance with increasing volatility, interrupted by depletions in W, Mo, Ni and Zn, and enrichments in Au, As, Ga and Ge. CI-normalized Os abundances range from ˜2 to 65, and are correlated with increasing Os/Pt, Os/Ni and Os/Pd ratios. CI-normalized Pt/Os ratios range from ˜0.3 to 1. Bulk cohenite-bearing spherules have siderophile element abundances indistinguishable from those of grain boundary metal in the same sample. CI-normalized patterns of most siderophile elements in the metal are, within error, identical to those of the bulk rock (at 25-40× higher abundances) in each sample. There are no correlations between siderophile element abundances and Fo. We infer that at T ? 1200 °C ureilites contained immiscible Fe-C (3-4 wt.% C) and Fe-S melts, small samples of which were trapped as the spherules within silicates. The Fe-S melt was largely extracted from the rocks, and the bulk of the residual Fe-C melt is now represented by the grain boundary metal. Assuming that ureilite precursor materials had CI or CV abundances of siderophile elements, the large fractionations of HSE observed in metal in 7 of the 10 samples require extremely high degrees (>98%) of batch Fe-S melt extraction, which implies very high xFeS (= wt. FeS/[Fe + FeS]) in the precursors. Furthermore, at such high degrees of fractionation, the HSE are so strongly concentrated into the residual metal that to match their relatively low absolute abundances in the ureilite metal, very high initial metal contents are required. Together, these constraints would imply that ureilite precursors had abundances of Fe metal and FeS (˜20-35 wt.% each) far exceeding those of known CC or OC. These requirements could be relaxed, permitting lower (more plausible) degrees of melting and lower initial metal and sulfide abundances, if ureilite precursors were volatile-depleted to a greater extent than bulk CV. We suggest that ureilite precursors contained, to various degrees, an overabundance (relative to chondrites) of refractory-enriched material such as CAIs. Excess CAIs could also account for observed depletions of W and Mo (otherwise difficult to explain) in the ureilite metal, and lead to the observed range of siderophile element patterns and abundances among samples. Such a model can potentially explain the lack of correlation between siderophile element abundances and FeO (or olivine Fo), and reconcile the metal and siderophile element data with a redox model for ureilite petrogenesis.

  12. Pixe analysis of the platinum group elements preconcentrated from geological samples

    NASA Astrophysics Data System (ADS)

    Annegarn, H. J.; Erasmus, C. S.; Sellschop, J. P. F.

    1984-04-01

    A fast multi-elemental method of measuring the platinum group elements (PGEs) in geological samples is needed for the geochemical study and the commercial exploitation of these metals. The application of particle induced X-ray emission (PIXE) for the determination of ng-range concentrations of platinum, palladium, rhodium and ruthenium in terrestrial rocks is described. The PGEs are inhomogeneously distributed in sulphide ores and their host rocks, necessitating the analysis of large sample aliquots to obtain representative results. Preconcentration of the sample material is therefore essential for their analysis by PIXE. The noble metals are extracted from a 50 g sample by a modified nickel sulphide fire-assay technique. The resulting NiS button is partly dissolved in hydrochloric acid and the insoluble noble metal sulphides are retained on a Nuclepore filter membrane which is then used directly as a target for PIXE analysis. The method was evaluated by the analysis of serially diluted samples of a standard reference material of a platinum bearing ore. X-ray spectrum optimisation was investigated using differential X-ray absorbers. Detection limits of ˜ 0.5 ng/g were established for the elements Rh, Ru, Pd and Pt. The low detection limits and relative simplicity of analysis by PIXE compare favourably with other recently developed procedures.

  13. Trans-iron group elements in hot helium-rich white dwarfs

    NASA Astrophysics Data System (ADS)

    Werner, Klaus

    2014-10-01

    Our recent detection of twelve trans-iron group elements (Z=30-56) in the hot helium-rich white dwarf (i.e. spectral type DO) RE0503-289 is a unique discovery. This phenomenon was never observed before in any white dwarf. Abundance analyses hitherto performed for five species (Zn, Ge, Kr, Xe, Ba) reveal values between 155 and 23000 times solar. There are reasons to believe that these extreme overabundances are connected to the evolutionary history of the DO white dwarfs. They are the outcome of a late helium-shell flash that consumes all hydrogen in the stellar envelope and at the same time dredges up helium-rich intershell matter that is enriched with s-process elements. These elements were synthesised in the preceding AGB phase of the evolution. We argue that if RE0503-289 is a typical representative of the DO white dwarfs, then all DOs with similar effective temperature should also show these extraordinary chemical diversity and overabundances. In order to prove this hypothesis, we want to obtain FUV spectra of two other hot DO white dwarfs plus a representative of the PG1159 stars, which are thought to be immediate progenitors of DO white dwarfs. If all three targets show the same heavy-metal abundance pattern, then these objects hold the promise that their metal abundances can be used to constrain AGB star nucleosynthesis. If otherwise RE0503-289 remains a unique object, then an alternative evolutionary scenario (binary WD merger) is probably responsible for its extreme element abundances.

  14. Rhenium and platinum group element abundances correlated with mantle source components in Hawaiian picrites: sulphides in the plume

    Microsoft Academic Search

    V. C. Bennett; M. D. Norman; M. O. Garcia

    2000-01-01

    Core addition and crustal recycling models that seek to explain the radiogenic Os isotopic compositions of primitive Hawaii tholeiites predict distinctive geochemical consequences for chalcophile and siderophile element abundances in the mantle plume. To test these models and to improve our understanding of compositional variability in the Hawaiian plume, the platinum group element (PGE) and Re contents of primitive shield

  15. Sequence similarity of putative transposases links the maize Mutator autonomous element and a group of bacterial insertion sequences.

    PubMed Central

    Eisen, J A; Benito, M I; Walbot, V

    1994-01-01

    The Mutator transposable element system of maize is the most active transposable element system characterized in higher plants. While Mutator has been used to generate and tag thousands of new maize mutants, the mechanism and regulation of its transposition are poorly understood. The Mutator autonomous element, MuDR, encodes two proteins: MURA and MURB. We have detected an amino acid sequence motif shared by MURA and the putative transposases of a group of bacterial insertion sequences. Based on this similarity we believe that MURA is the transposase of the Mutator system. In addition we have detected two rice cDNAs in genbank with extensive similarity to MURA. This sequence similarity suggests that a Mutator-like element is present in rice. We believe that Mutator, a group of bacterial insertion sequences, and an uncharacterized rice transposon represent members of a family of transposable elements. PMID:8041625

  16. Trace element chemistry of Cumulus Ridge 04071 pallasite with implications for main group pallasites

    NASA Astrophysics Data System (ADS)

    Danielson, L. R.; Righter, K.; Humayun, M.

    2009-08-01

    Pallasites have long been thought to represent samples from the metallic core-silicate mantle boundary of a small asteroid-sized body, with as many as ten different parent bodies recognized recently. This report focuses on the description, classification, and petrogenetic history of pallasite Cumulus Ridge (CMS) 04071 using electron microscopy and laser ablation ICP-MS. Most olivines are angular in CMS 04071, but there are some minor occurrences of small rounded olivines, such as in the Eagle Station pallasite. Olivine, chromite, and metal compositions indicate that CMS 04071 can be classified as a Main Group pallasite. The kamacite/taenite partition coefficients (D) for highly siderophile elements (HSE) are all close to 1, but comparison with previous studies on iron meteorites and pallasites shows that variation of some D values is controlled by the Ni content of taenite. D(HSE metal/sulfide for Re, Cu, and Cr all are <1, indicating chalcophile behavior for these three elements, in agreement with experimental Dmetal/sulfide. D(HSE)metal/olivine are variable, which is perhaps due to small metallic inclusions in the olivine that are present to variable extents in different pallasites. All of these data, together with results from previous studies, indicate that the CMS pallasites were likely formed at the core-mantle boundary of a small asteroid, but not necessarily related to the core that produced the IIIAB irons. In addition, they share a similar volatile element depletion to HEDs that is distinct from other bodies such as Earth, Mars, Angrite Parent Body, and the parent body of the brachinites.

  17. p-electron magnetism in CdS doped with main group elements.

    PubMed

    Bedolla, P O; Gruber, C; Mohn, P; Redinger, J

    2012-11-28

    On the basis of ab initio supercell calculations employing density functional theory (DFT) and post-DFT methods, we investigate the behavior of main group element impurities (B, C, N, Al, Si, P, Ga, Ge) in wurtzite (w) and zincblende (zb) CdS lattices. It is found that the impurities prefer the sulfur position and most of them, depending on the concentration, exhibit magnetic order. We find that for small concentrations (64zb and 72w supercells) a half-metallic behavior is found. For a 16-atom supercell for both the zb- and w-structure partly also unsaturated magnetic moments occur. The field dependence of the magnetic moments in these materials may lead to new technological applications of these magnetic semiconductors as tunable spin injection materials. PMID:23111101

  18. p-electron magnetism in CdS doped with main group elements

    NASA Astrophysics Data System (ADS)

    Bedolla, P. O.; Gruber, C.; Mohn, P.; Redinger, J.

    2012-11-01

    On the basis of ab initio supercell calculations employing density functional theory (DFT) and post-DFT methods, we investigate the behavior of main group element impurities (B, C, N, Al, Si, P, Ga, Ge) in wurtzite (w) and zincblende (zb) CdS lattices. It is found that the impurities prefer the sulfur position and most of them, depending on the concentration, exhibit magnetic order. We find that for small concentrations (64zb and 72w supercells) a half-metallic behavior is found. For a 16-atom supercell for both the zb- and w-structure partly also unsaturated magnetic moments occur. The field dependence of the magnetic moments in these materials may lead to new technological applications of these magnetic semiconductors as tunable spin injection materials.

  19. What Factors Control Platinum-Group Element (PGE) Abundances in Basalts From the Ontong Java Plateau?

    NASA Astrophysics Data System (ADS)

    Chazey, W. J.; Neal, C. R.

    2002-12-01

    Eleven samples encompassing four sites drilled by Ocean Drilling Program Leg 192 to the Ontong Java Plateau (OJP) were analyzed for major, trace and platinum-group (PGEs: Ir, Ru, Rh, Pt, and Pd) elements. Based on major and trace element chemistry, these are divided into two groups: a primitive group, which was newly discovered on Leg 192, and Kwaimbaita-type basalts, which are ubiquitous on the OJP (cf. Tejada et al., 2002, J. Pet. 43:449). The primitive group is relatively enriched in MgO, Ni, and Cr and relatively depleted in incompatible elements compared to the Kwaimbaita-type basalts. Petrography indicates that the fractionating phases during emplacement of both types of basalts were olivine and Cr-spinel +/- plagioclase +/- cpx. Normalized PGE profiles are fractionated, but exhibit a flattening between Ru and Ir and occasionally an enrichment in Ir. It has been shown that chromite can preferentially incorporate Os and Ru (Kd ?150) over Ir (Kd ?100), which may account for the Ir and Ru systematics. We do not consider sulfide to be a factor in fractionating the PGEs because it is either absent or present as a trace phase in these basalts and the OJP basalts are sulfur undersaturated (Michael and Cornell, 1996, EOS 77:714). Additionally, the primitive samples from the OJP also have Cu/Pd ratios (4500-8000) that are roughly similar to primitive mantle (7300), and have a generally flat transition from Pd to Y on a primitive mantle-normalized plot. It is unlikely that these samples reached sulfur saturation. The Kwaimbaita-type basalts have slightly elevated Cu/Pd ratios (9000-14000). While there are subtle differences between the PGE profiles of basalts from the Leg 192 drill cores compared to OJP basalts from subaerial outcrops in the Solomon Islands (e.g., the former have general lower Pt/Rh and higher Rh/Ru ratios), it is apparent that silicate and oxide phases are controlling the PGE profiles and abundances. For example, the six samples analyzed from Site 1185 demonstrate a positive correlation of Ru and Ir with Cr and Ni, suggesting a close association of these elements with the observed olivine and Cr-spinel phenocrysts. For all OJP basalts for which we have PGE data, there is a general positive correlation using MgO (or Cr or Ni) as a fractionation index and PGE abundance as well as ratios such as Pt/Y. Therefore, fractional crystallization controls the PGE contents of the OJP basalts. However, as noted by Ely and Neal (2002, Chem. Geol., in press) the abundances require a source enriched in the PGEs over upper mantle and, in some cases, primitive mantle. Such sources require a PGE enriched component that could be from the outer core, although as noted by Parkinson et al. (2001, EOS 82:F1398) this component is not always required. Further work is underway to substantiate this.

  20. Divisions Iv-V / Working Group ap & Related Stars

    NASA Astrophysics Data System (ADS)

    Mathys, Gautier; Cunha, Margarida; Dworetsky, Michael; Kochukhov, Oleg; Kupka, Friedrich; LeBlanc, Francis; Monier, Richard; Paunzen, Ernst; Pintado, Olga; Piskunov, Nikolai; Ziznovsky, Jozef

    2012-04-01

    The purpose of the Working Group on Ap and Related Stars (ApWG) is to promote and facilitate research about stars in the spectral type range from B to early F that exhibit surface chemical peculiarities and related phenomena. This is a very active field of research, in which a wide variety of new developments have taken place since 2009, as illustrated by the following selected highlights.

  1. Deformation And Polarization In Single Walled Carbon Nanotube Due To Doping Of Group-IV Elements: A First Principle Investigations

    NASA Astrophysics Data System (ADS)

    Chakraborty, Brahmananda; Modak, P.; Banerjee, S.

    2010-12-01

    We have performed first principles calculations using Density Functional Theory to study atomic and electronic structure of Single Walled Carbon Nanotube (SWNT) doped with group-IV elements (Si, Ge, Sn). Substitution doping of group-IV elements (Si, Ge, Sn) results in deformation and local polarization of perfect SWNT. Because of the large size of the dopant atom it stays 1-2 Å above the tube and introduces angular deformation where ?CSnC angle becomes 79.8 degree for Sn instead of 120 degree for perfect SWNT. For semi-conducting SWNT the band gap at the Fermi level reduces with doping of element having higher Z value and the system make a march towards metallic behavior. Silicon substitute SWNT is more stable compared to Sn and Ge substitution. This study will be helpful in finding stability and electronic structures of various new and hypothetical carbon nanomaterials formed with substitution doping of group-IV elements.

  2. Olivine Morphology and Trace Element Fractionation in Metal of Main Group Pallasites

    NASA Astrophysics Data System (ADS)

    Kissin, S. A.

    2009-05-01

    Pallasites are stony-iron meteorites consisting largely of olivine macrocrysts in a matrix of iron-nickel alloy in the form of kamacite-taenite intergrowth. Pallasites have been divided into Main Group (PMG), Eagle Station Grouplet (PES) and ungrouped (IrUn) also called pyroxene pallasites. Within PMG, six have anomalous metal contents (PMGam) and five have anomalous olivine compositions (PMGas). The morphologies of olivine macrocrysts in PMG are essentially of two types, angular or rounded. Of 19 normal PMG whose compositions and olivine morphologies are known, 17 have angular olivines. In the remaining two PMG, olivines are rounded as well as those of three PMGam and three PMGas. Experimental studies have demonstrated that rounding of olivines in molten iron-nickel alloy occurs in short times on a geological scale. Metallic cooling rates for PMG have been shown to be rapid at high temperature and slow at low temperature. Detailed analyses have demonstrated that angular olivines are compositionally zoned and therefore not in equilibrium with metal. These conditions imply that molten metal was injected into angular olivines fractured by an impact event. However, the presence of rounded olivine macrocrysts in PMGam and PMGas, as well as in two normal PMG, implies that these pallasites have retained an earlier generation of olivine. A long-standing theory for the origin of pallasites is that they represent the core-mantle boundary of a parent- body, subsequently disrupted by impact and injected by impact-melted metal. A relationship between the trace element fractionation trend in group IIIAB iron meteorites and metal of PMG is evident in that normal members cluster at the end of this fractionation trend. However, the theory does not account for the presence of rounded olivine macrocrysts. Log trace element vs log Au plots of indicate that most PMGam members exhibit the same fractionation trend as that seen for group IIIAB irons, and these correlate with PMGam and PMGas members with rounded olivines. The rounded olivine marcrocrysts may represent pre-impact olivines trapped in fractionating group IIIAB metal. Some scatter in these plots may be attributed to crystallization of melt trapped among olivine macrocrysts. Thus, the core-mantle boundary theory for the original of PMG is consistent with the evidence seen in olivine macrocrysts.

  3. Coronal Element Abundances in the G8 V Star XI Boo A

    NASA Astrophysics Data System (ADS)

    Laming, J. Martin; Drake, Jeremy J.

    1999-04-01

    We present a detailed analysis of a deep EUVE exposure (270 ks) of the G8 V star xi Boo A. We evaluate electron densities from line ratios in Fe X, Fe XII, Fe XIII, and Fe XIV, and use the intensities of lines from ions Fe IX - XXII to establish the emission measure distribution. We also observe and measure emission in lines from Ne VII, Mg VII - IX, Si VII, VIII, X, XII, S XII - XIV, Ar XV, XVI, Ca XIV - XVII, and Ni XVII, XVIII, from which we derive relative abundances in the corona of xi Boo A. We find very strong evidence for the FIP (First Ionization Potential) effect, in that the abundances of low FIP elements Mg, Si, Ca, Fe, and Ni appear to be enhanced by a factor of about 4 over those of the high FIP elements S and Ar, relative to their photospheric values. Thus xi Boo A joins alpha Cen B (K2 V) and possibly epsilon Eri (K2 V) in showing similar coronal abundance anomalies to those observed in the Sun, in contrast to Procyon (F5 IV) whose corona appears to have similar composition to its photosphere.

  4. Impact Behavior of A356 Foundry Alloys in the Presence of Trace Elements Ni and V

    NASA Astrophysics Data System (ADS)

    Casari, Daniele; Ludwig, Thomas H.; Merlin, Mattia; Arnberg, Lars; Garagnani, Gian Luca

    2015-02-01

    In the present work, the impact behavior of unmodified A356 alloys with the addition of Ni or V in as-cast and T6 heat-treated conditions was assessed. Charpy V-notched specimens obtained from sand and permanent mold casting showed low total absorbed energy average values ( W t < 2 J). SEM analysis of fracture profiles and surfaces indicated a Si-driven crack propagation with a predominant transgranular fracture mode. Occasionally, intergranular contributions to fracture were detected in the permanent mold cast alloys due to the locally finer microstructure. Concurrent mechanisms related to the chemical composition, solidification conditions and heat treatment were found to control the impact properties of the alloys. While the trace element Ni exerted only minor effects on the impact toughness of the A356 alloy, V had a strong influence: (i) V-containing sand cast alloys absorbed slightly higher impact energies compared to the corresponding A356 base alloys; (ii) in the permanent mold cast alloys, V in solid solution led to a considerable loss of ductility, which in turn decreased the total absorbed energy.

  5. Architectural and Functional Diversity of Polycomb Group Response Elements in Drosophila

    PubMed Central

    Brown, J. Lesley; Kassis, Judith A.

    2013-01-01

    Polycomb group response elements (PREs) play an essential role in gene regulation by the Polycomb group (PcG) repressor proteins in Drosophila. PREs are required for the recruitment and maintenance of repression by the PcG proteins. PREs are made up of binding sites for multiple DNA-binding proteins, but it is still unclear what combination(s) of binding sites is required for PRE activity. Here we compare the binding sites and activities of two closely linked yet separable PREs of the Drosophila engrailed (en) gene, PRE1 and PRE2. Both PRE1 and PRE2 contain binding sites for multiple PRE–DNA-binding proteins, but the number, arrangement, and spacing of the sites differs between the two PREs. These differences have functional consequences. Both PRE1 and PRE2 mediate pairing-sensitive silencing of mini-white, a functional assay for PcG repression; however, PRE1 requires two binding sites for Pleiohomeotic (Pho), whereas PRE2 requires only one Pho-binding site for this activity. Furthermore, for full pairing-sensitive silencing activity, PRE1 requires an AT-rich region not found in PRE2. These two PREs behave differently in a PRE embryonic and larval reporter construct inserted at an identical location in the genome. Our data illustrate the diversity of architecture and function of PREs. PMID:23934890

  6. High selectivity and flat group delay parallel-coupled microstrip bandpass filter with lumped-element K-inverters

    Microsoft Academic Search

    Yun-Wei Lin; Jhe-Ching Lu; Chi-Yang Chang; Ching-Ku Liao

    2010-01-01

    In this paper, high selectivity and flat group delay parallel-coupled microstrip bandpass filter with lump element K-inverter are proposed. By using delay line, cross coupling is introduced and controlled easily to generate finite transmission zeros for selectivity and flat group delay. Finally, 5th-order and 6th-order filters with high selectivity and flat group delay are given as examples.

  7. Re-187-Os-187, Pt-190-Os-186 Isotopic and Highly Siderophile Element Systematics of Group IVA Irons

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; McCoy, T. J.; Schulte, R. F.; McDonough, W. F.; Ash, R. D.

    2005-01-01

    We have recently completed Re-187-Os-187 and Pt-190-Os-186 isotopic and elemental studies of the two largest magmatic iron meteorite groups, IIAB and IIIAB [1]. These studies revealed closed-system behavior of both isotopic systems, but complex trace element behavior for Re, Pt and Os in group IIIAB. Here we examine isotopic and trace elemental systematics of group IVA irons. The IVA irons are not as extensively fractionated as IIAB and IIIAB and their apparently less complex crystallization history may make for more robust interpretation of the relative partitioning behavior of Re, Pt and Os, as well as the other highly siderophile elements (HSE) measured here; Pd, Ru and Ir [e.g. 2]. An additional goal of our continuing research plan for iron meteorites is to assess the possibility of relating certain ungrouped irons with major groups via trace element modeling. Here, the isotopic and trace element systematics of the ungrouped irons Nedagolla and EET 83230 are compared with the IVA irons.

  8. Properties of Group-IV, III-V and II-VI Semiconductors

    Microsoft Academic Search

    Sadao Adachi

    2005-01-01

    Almost all the semiconductors of practical interest are the group-IV, III-V and II-VI semiconductors and the range of technical applications of such semiconductors is extremely wide. The purpose of this book is twofold: * to discuss the key properties of the group-IV, III-V and II-VI semiconductors * to systemize these properties from a solid-state physics aspect The majority of the

  9. On-line gas phase chromatography of the bromides of the group 4, 5, and 6 elements

    SciTech Connect

    Sylwester, E.R.; Gregorich, K.E.; Lee, D.M.; Chung, Y.H. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-12-31

    Gas phase chromatography has been used to determine the volatility of bromides of the group 4, 5, and 6 elements, including the transactinides 104 (Rf) and 105 (Ha). The Heavy Element Volatility Instrument (HEVI) was used to measure the volatilities of the bromides of short-lived isotopes of these elements. Adsorption enthalpy values were calculated from the observed volatilities using a Monte Carlo program. The values for RfBr{sub 4} and HaBr{sub 5} are similar to ZrBr{sub 4} and NbBr{sub 5} rather than to HfBr{sub 4} and TaBr{sub 5}. This deviates from a simple extrapolation from periodic table trends and may indicate the influence of relativistic effects on the electronic level structure of these transactinides. The group 6 element Seaborgium (Sg) has not yet been studied due to the low production cross-section.

  10. Mineralogical siting of platinum-group elements in pentlandite from the Bushveld Complex, South Africa

    NASA Astrophysics Data System (ADS)

    Junge, Malte; Wirth, Richard; Oberthür, Thomas; Melcher, Frank; Schreiber, Anja

    2015-01-01

    The Bushveld Complex in South Africa hosts the world's largest resources of platinum-group elements (PGEs), which are mainly mined from three ore bodies, namely the Merensky Reef, the UG-2 chromitite, and the Platreef. In these ores, the PGEs are bimodally distributed, occurring both as discrete platinum-group minerals (PGMs) and hosted by sulfides. The presence of PGEs in sulfides has been demonstrated by electron probe microanalysis, laser ablation induced coupled plasma mass spectrometry, secondary ion mass spectrometry, and particle-induced X-ray emission. However, evidence is lacking on the mineralogical siting of the PGEs, e.g., whether they occur in solid solution, as nano-inclusions, and/or micro-inclusions. Therefore, in the present study, a combination of focused ion beam and transmission electron microscopy was used which allows to obtain crystal structural relationships between the host mineral and incorporated trace elements and revealing the physicochemical state of the PGE in sulfides. The present study confirms the existence of micrometer-sized discrete PGMs in the ores. Further, the PGEs occur in a number of forms, namely (1) as discrete nano-inclusions of PGMs, (2) as patchily distributed solid solution, (3) ordered within the pentlandite crystal structure, substituting for Ni and/or Fe (superlattice), and (4) as homogenous solid solution. Nanometer-sized PGMs (nPGMs) show no orientation relationship with the host sulfide mineral. Consequently, they are discrete phases, which were trapped within pentlandite during sulfide growth. Heterogeneous and patchy distributions of Rh and Ir within the pentlandite lattice suggest that Rh and Ir were already present within the sulfide liquid. The absence of possible reaction partners (e.g., Bi, As, and Sn) necessary for the formation of discrete PGMs forced Rh and Ir to remain in the crystal lattice of pentlandite and down-temperature exsolution caused patchy distribution patterns of Rh and Ir. High concentrations of Rh and Ir in pentlandite initiate ordering of the randomly distributed PGE in form of nanometer-sized lamellae resulting in the formation of a superlattice. Palladium is homogenously distributed within the pentlandite lattice, even at high Pd concentrations, and in addition also occurs as nPGMs.

  11. 20 CFR 655.1115 - Element V-What does “no strike/lockout or layoff” mean?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...V-What does âno strike/lockout or layoffâ mean? 655.1115 Section 655.1115 Employees' Benefits EMPLOYMENT AND TRAINING...H-1C Nonimmigrant Workers as Registered Nurses? § 655.1115 Element V—What does “no strike/lockout...

  12. Smoothed particle hydrodynamics and element bending group modeling of flexible fibers interacting with viscous fluids

    NASA Astrophysics Data System (ADS)

    Yang, Xiufeng; Liu, Moubin; Peng, Shiliu

    2014-12-01

    This paper presents a smoothed particle hydrodynamics (SPH) and element bending group (EBG) coupling method for modeling the interaction of flexible fibers with moving viscous fluids. SPH is a well-developed mesh-free particle method for simulating viscous fluid flows. EBG is also a particle method for modeling flexible bodies. The interaction of flexible fibers with moving viscous fluids is rendered through the interaction of EBG particles for flexible fiber and SPH particles for fluid. In numerical simulation, flexible fibers of different lengths are immersed in a moving viscous fluid driven by a body force. The drag force on the fiber obtained from SPH-EBG simulation agrees well with experimental observations. It is shown that the flexible fiber demonstrates three typical bending modes, including the U-shaped mode, the flapping mode, and the closed mode, and that the flexible fiber experiences a drag reduction due to its reconfiguration by bending. It is also found that the U 4/3 drag scaling law for a flexible fiber is only valid for the U-shaped mode, but not valid for the flapping and closed modes. The results indicate that the reconfiguration of a flexible fiber is caused by the fluid force acting on it, while vortex shedding is of importance in the translations of bending modes.

  13. Platinum group elements in raptor eggs, faeces, blood, liver and kidney.

    PubMed

    Ek, Kristine H; Rauch, Sebastien; Morrison, Gregory M; Lindberg, Peter

    2004-12-01

    The increased use of platinum group elements (PGEs) in automobile catalysts and their emission into the environment has led to a concern over environmental and particularly biological accumulation. Specimens of samples from raptors are useful for the investigation of the impact of PGEs because these birds are found in both urban and rural environments and are invariably at the top of the food chain. Platinum (Pt), palladium (Pd) and rhodium (Rh) concentrations were determined by quadrupole Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in eggs of the sparrowhawk (Accipiter nisus) and the peregrine falcon (Falco peregrinus), and in blood, liver and kidney of the peregrine falcon, while only Pt was determined in faeces of the peregrine falcon and the gyrfalcon (Falco rusticolus). PGE concentrations were higher in blood compared to both faeces and eggs, while liver and kidney concentrations were not elevated indicating no bioaccumulation through metallothionein pathways. A significant spatial trend could only be established for Pt in faeces. The general lack of a spatial trend is probably due to the widespread distribution of automobiles and the long-range transport of nanoparticles containing PGEs, and because birds migrate and forage over large areas. No significant temporal trend could be established. Higher relative concentrations of Pd, followed by Rh and Pt, indicate a mobility gradient of Pd>Rh>Pt. PMID:15504501

  14. Platinum-group elements in mafic and ultramafic rocks in Alaska

    SciTech Connect

    Foley, J.Y. (Bureau of Mines, Anchorage, AK (United States). Alaska Field Operations Center)

    1993-04-01

    Anomalous concentrations of platinum-group elements (PGE) have been geochemically detected or PGE minerals have been identified at over 100 sites in Alaska. These sites include both placer and lode occurrences; most are in areas that are underlain by or are derived from mafic and ultramafic rocks. PGE-bearing mafic-ultramafic rocks in Alaska comprise Ural-Alaskan, ophiolitic, layered, sill-form, composite, and miscellaneous other types of igneous complexes. Production of PGE minerals in Alaska has predominantly been from placers and lobes associated with Ural-Alaskan type complexes (Goodnews Bay and Salt Chuck complexes). Minor productions of PGE minerals from placer gold concentrates is reported at more numerous sites where alluvium has eroded from more varied mafic-ultramafic provenances. PGE occur in several tectonic settings in Alaska. Among the identified lode occurrences, outstanding examples exist in supra-subduction settings of the western Brooks Range and Border Ranges ophiolite complexes. In active continental margin accretionary complexes of the eastern and central Alaska Range, composite plutons and a belt of highly differentiated, mostly sill-form intrusions host PGE occurrences of varied chemical, mineralogic, and petrologic character. Ural-Alaskan type complexes tend to occur in volcanic arc settings. Lacking in Alaska are Archean layered mafic complexes; Tertiary analogues in southeastern Alaska locally contain PGE associated with iron-copper-nickel sulfide minerals.

  15. Platinum group element incorporation into human bones resulting from increased anthropogenic utilization

    NASA Astrophysics Data System (ADS)

    Darrah, T. H.; Hannigan, R. E.; Campbell, E.; Prutsman-Pfeiffer, J.

    2009-12-01

    Platinum group elements (including Pt, Pd, Ru, Rh, Os, Ir) are rare precious metals that occur at exceedingly low concentrations in the Earth’s crust (~0.02-0.5 ng/g). Utilization of PGEs in the catalytic converter of automobiles, medical treatments, electronics, and as a catalyst, has rapidly increased since the early 20th century, leading to increased anthropogenic PGE emissions and consequently increasing concentrations in the environment. Recent reports indicate that environmental PGE concentrations are increasing in urban air, roadside soils, and aquatic environments (Rauch and Morrison, 2008). As a result, there is an increased potential for PGE uptake into the biosphere. To evaluate bio-incorporation of PGEs into the human body we use ICP-MS to analyze for PGE concentration in human bones. Human bone minerals serve as a reservoir for the majority of the body’s trace metals and provide a measure of PGE incorporation into the human body from various environmental sources. We compare PGE concentrations in femoral heads of 30 present-day modern humans to those in femurs of 10 humans exhumed from 18th and 19th century burial sites, whose metal exposures predate extensive anthropogenic use of PGEs.

  16. Smoothed particle hydrodynamics and element bending group modeling of flexible fibers interacting with viscous fluids.

    PubMed

    Yang, Xiufeng; Liu, Moubin; Peng, Shiliu

    2014-12-01

    This paper presents a smoothed particle hydrodynamics (SPH) and element bending group (EBG) coupling method for modeling the interaction of flexible fibers with moving viscous fluids. SPH is a well-developed mesh-free particle method for simulating viscous fluid flows. EBG is also a particle method for modeling flexible bodies. The interaction of flexible fibers with moving viscous fluids is rendered through the interaction of EBG particles for flexible fiber and SPH particles for fluid. In numerical simulation, flexible fibers of different lengths are immersed in a moving viscous fluid driven by a body force. The drag force on the fiber obtained from SPH-EBG simulation agrees well with experimental observations. It is shown that the flexible fiber demonstrates three typical bending modes, including the U-shaped mode, the flapping mode, and the closed mode, and that the flexible fiber experiences a drag reduction due to its reconfiguration by bending. It is also found that the U4/3 drag scaling law for a flexible fiber is only valid for the U-shaped mode, but not valid for the flapping and closed modes. The results indicate that the reconfiguration of a flexible fiber is caused by the fluid force acting on it, while vortex shedding is of importance in the translations of bending modes. PMID:25615191

  17. The nature of the interaction of dimethylselenide with IIIA group element compounds.

    PubMed

    Madzhidov, Timur I; Chmutova, Galina A

    2013-05-16

    The first systematic theoretical study of the nature of intermolecular bonding of dimethylselenide as donor and IIIA group element halides as acceptors was made with the help of the approach of Quantum Theory of Atoms in Molecules. Density Functional Theory with "old" Sapporo triple-? basis sets was used to calculate geometry, thermodynamics, and wave function of Me2Se···AX3 complexes. The analysis of the electron density distribution and the Laplacian of the electron density allowed us to reveal and explain the tendencies in the influence of the central atom (A = B, Al, Ga, In) and halogen (X = F, Cl, Br, I) on the nature of Se···A bonding. Significant changes in properties of the selenium lone pair upon complexation were described by means of the analysis of the Laplacian of the charge density. Charge transfer characteristics and the contributions to it from electron localization and delocalization were analyzed in terms of localization and delocalization indexes. Common features of the complexation and differences in the nature of bonding were revealed. Performed analysis evidenced that gallium and indium halide complexes can be attributed to charge transfer-driven complexes; aluminum halides complexes seem to be mainly of an electrostatic nature. The nature of bonding in different boron halides essentially varies; these complexes are stabilized mainly by covalent Se···B interaction. In all the complexes under study covalence of the Se···A interaction is rather high. PMID:23590617

  18. High salinity volatile phases in magmatic Ni-Cu-platinum group element deposits

    NASA Astrophysics Data System (ADS)

    Hanley, J. J.; Mungall, J. E.

    2004-12-01

    The role of "deuteric" fluids (exsolved magmatic volatile phases) in the development of Ni-Cu-PGE (platinum group element) deposits in mafic-ultramafic igneous systems is poorly understood. Although considerable field evidence demonstrates unambiguously that fluids modified most large primary Ni-Cu-PGE concentrations, models which hypothesize that fluids alone were largely responsible for the economic concentration of the base and precious metals are not widely accepted. Determination of the trace element composition of magmatic volatile phases in such ore-forming systems can offer considerable insight into the origin of potentially mineralizing fluids in such igneous environments. Laser ablation ICP-MS microanalysis allows researchers to confirm the original metal budget of magmatic volatile phases and quantify the behavior of trace ore metals in the fluid phase in the absence of well-constrained theoretical or experimental predictions of ore metal solubility. In this study, we present new evidence from major deposits (Sudbury, Ontario, Canada; Stillwater Complex, Montana, U.S.A.) that compositionally distinct magmatic brines and halide melt phases were exsolved from crystallizing residual silicate melt and trapped within high-T fluid conduits now comprised of evolved rock compositions (albite-quartz graphic granite, orthoclase-quartz granophyre). Petrographic evidence demonstrates that brines and halide melts coexisted with immiscible carbonic phases at the time of entrapment (light aliphatic hydrocarbons, CO2). Brine and halide melt inclusions are rich in Na, Fe, Mn, K, Pb, Zn, Ba, Sr, Al and Cl, and homogenize by either halite dissolution at high T ( ˜450-700° C) or by melting of the salt phase (700-800° C). LA-ICPMS analyses of single inclusions demonstrate that high salinity volatile phases contained abundant base metals (Cu, Fe, Sn, Bi) and precious metals (Pt, Pd, Au, Ag) at the time of entrapment. Notably, precious metal concentrations in the inclusions are comparable to and often exceed the economic concentrations of the metals within the ores themselves. As a consequence of these results, current genetic models must be revised to consider the role played by hydrous saline melts and magmatic brines in deposit development, and the potential for interaction and competition between sulfide liquids (or PGE-bearing sulfide minerals) and hydrosaline volatiles for available PGE and Au in a crystallizing mafic igneous system must be critically evaluated.

  19. Theoretical predictions of properties and gas-phase chromatography behaviour of carbonyl complexes of group-6 elements Cr, Mo, W, and element 106, Sg

    NASA Astrophysics Data System (ADS)

    Pershina, V.; Anton, J.

    2013-05-01

    Fully relativistic, four-component density functional theory electronic structure calculations were performed for M(CO)6 of group-6 elements Cr, Mo, W, and element 106, Sg, with an aim to predict their adsorption behaviour in the gas-phase chromatography experiments. It was shown that seaborgium hexacarbonyl has a longer M-CO bond, smaller ionization potential, and larger polarizability than the other group-6 molecules. This is explained by the increasing relativistic expansion and destabilization of the (n - 1)d AOs with increasing Z in the group. Using results of the calculations, adsorption enthalpies of the group-6 hexacarbonyls on a quartz surface were predicted via a model of physisorption. According to the results, -?Hads should decrease from Mo to W, while it should be almost equal - within the experimental error bars - for W and Sg. Thus, we expect that in the future gas-phase chromatography experiments it will be almost impossible - what concerns ?Hads - to distinguish between the W and Sg hexacarbonyls by their deposition on quartz.

  20. Theoretical predictions of properties and gas-phase chromatography behaviour of carbonyl complexes of group-6 elements Cr, Mo, W, and element 106, Sg.

    PubMed

    Pershina, V; Anton, J

    2013-05-01

    Fully relativistic, four-component density functional theory electronic structure calculations were performed for M(CO)6 of group-6 elements Cr, Mo, W, and element 106, Sg, with an aim to predict their adsorption behaviour in the gas-phase chromatography experiments. It was shown that seaborgium hexacarbonyl has a longer M-CO bond, smaller ionization potential, and larger polarizability than the other group-6 molecules. This is explained by the increasing relativistic expansion and destabilization of the (n - 1)d AOs with increasing Z in the group. Using results of the calculations, adsorption enthalpies of the group-6 hexacarbonyls on a quartz surface were predicted via a model of physisorption. According to the results, -?Hads should decrease from Mo to W, while it should be almost equal--within the experimental error bars--for W and Sg. Thus, we expect that in the future gas-phase chromatography experiments it will be almost impossible--what concerns ?Hads--to distinguish between the W and Sg hexacarbonyls by their deposition on quartz. PMID:23656128

  1. Measurements of total atomic attenuation cross sections of Tm, Yb, Lu, Hf, Ta, W, Re and Os Elements at 122keV and 136keV

    SciTech Connect

    Kaya, N.; Tirasoglu, E.; Apaydin, G.; Kobya, A. I. [Karadeniz Technical University, Faculty of Arts and Sciences, Department of Physics, Trabzon, 61080 (Turkey)

    2007-04-23

    The aim of this study was to measure the total atomic attenuation cross sections ({sigma}t) in eighth elements (69{<=}Z{<=}76) at 122 keV and 136 keV. The experimental values of the cross sections were determined using the transmission geometry. Measurements have been performed using an annular source (Co-57) and Ultra-LEGe solid state detector with a resolution of 150 eV at 5.9 keV. Experimental results have been compared with theoretically calculated values and other available experimental results. Good agreement was observed among the experimental, theoretical and other experimental values.

  2. Report of the IAU\\/IAG Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites: 2000

    Microsoft Academic Search

    V. K. Abalakin; M. Bursa; M. E. Davies; C. de Bergh; J. H. Lieske; J. Oberst; J. L. Simon; E. M. Standish; P. Stooke; P. C. Thomas

    2002-01-01

    Every three years the IAU\\/IAG Working Group on cartographic coordinates and rotational elements of the planets and satellites revises tables giving the directions of the north poles of rotation and the prime meridians of the planets, satellites, and asteroids. Also presented are revised tables giving their sizes and shapes. Changes since the previous report are summarized in the Appendix.

  3. CLINICAL TRIALS OFFICE The principal charge of this focus group was to identify the key elements of a Clinical Trials

    E-print Network

    of a Clinical Trials Office at the LSUHSC-NO Campus. We propose that the mission of the Clinical Trials OfficeCLINICAL TRIALS OFFICE The principal charge of this focus group was to identify the key elements is to organize and enhance operational processes that support clinical research and facilitate the timely

  4. An experimental study of mass transfer of platinum-group elements, gold, nickel and copper in sulfur-dominated vapor

    E-print Network

    Long, Bernard

    An experimental study of mass transfer of platinum-group elements, gold, nickel and copper of the system, and the sulfur fugacity ( f S2). In experiments containing only Au-alloy and monosulfide solid S contents, when Pt-alloys form in the donor system,Pt istransferred lessthan Pd. In experiments containing

  5. Platinum group elements in the feathers of raptors and their prey.

    PubMed

    Jensen, K H; Rauch, S; Morrison, G M; Lindberg, P

    2002-04-01

    Platinum (Pt), palladium (Pd), and rhodium (Rh) concentrations were determined in the feathers of three raptor species in Sweden, the sparrowhawk ( Accipiter nisus), the peregrine falcon ( Falco peregrinus), and the gyrfalcon ( Falco rusticolus), as well as the main prey of the sparrowhawk (the house sparrow, Passer domesticus) and the gyrfalcon (the willow grouse, Lagopus lagopus). The analysis of feathers from 1917-1999 revealed a clear temporal trend, with significantly higher Rh concentrations in sparrowhawk and peregrine falcon after 1986. There is evidence for increasing platinum group element (PGE) concentrations from 1917 to 1999 in peregrine falcon and sparrowhawk. This suggests that feathers reflect increased PGE concentrations in the environment over this time period. Mean concentrations of PGE in feathers of raptors after 1986 ranged from 0.3 to 1.8 ng x g(-1) for Pt, 0.6 to 2.1 ng x g(-1) for Pd (indicative values), and 0.1 to 0.6 ng x g(-1) for Rh. House sparrows in urban areas had significantly higher Pt and Pd concentrations than urban sparrowhawks. The higher Pd concentrations in relation to Pt and Rh may indicate the greater mobility of Pd in the environment. Although PGE concentrations are generally higher in birds living in urban areas, no significant spatial trend could be established. This is partly due to the widespread distribution of automobiles and partly because birds forage and integrate PGE exposure over large areas. Laser ablation analysis demonstrates that PGE contamination of feathers is predominantly external, consisting of small particles in the nanometer size range. Other indications of external contamination are that Pt and Pd levels are significantly higher in the vane than in the shaft and that PGE relative ratios (except Pd) reflect urban particles. PMID:11910463

  6. Airborne particulate matter, platinum group elements and human health: a review of recent evidence.

    PubMed

    Wiseman, Clare L S; Zereini, Fathi

    2009-04-01

    Environmental concentrations of the platinum group elements (PGE) platinum (Pt), palladium (Pd) and rhodium (Rh) have been on the rise, due largely to the use of automobile catalytic converters which employ these metals as exhaust catalysts. It has generally been assumed that the health risks associated with environmental exposures to PGE are minimal. More recent studies on PGE toxicity, environmental bioavailability and concentrations in biologically relevant media indicate however that environmental exposures to these metals may indeed pose a health risk, especially at a chronic, subclinical level. The purpose of this paper is to review the most recent evidence and provide an up-to-date assessment of the risks related to environmental exposures of PGE, particularly in airborne particulate matter (PM). This review concludes that these metals may pose a greater health risk than once thought for several reasons. First, emitted PGE may be easily mobilised and solubilised by various compounds commonly present in the environment, thereby enhancing their bioavailability. Second, PGE may be transformed into more toxic species upon uptake by organisms. The presence of chloride in lung fluids, for instance, may lead to the formation of halogenated PGE complexes that have a greater potential to induce cellular damage. Third, a significant proportion of PGE found in airborne PM is present in the fine fraction that been found to be associated with increases in morbidity and mortality. PGE are also a concern to the extent that they contribute to the suite of metals found in fine PM suspected of eliciting a variety of health effects, especially in vulnerable populations. All these factors highlight the need to monitor environmental levels of PGE and continue research on their bioavailability, behaviour, speciation and associated toxicity to enable us to better assess their potential to elicit health effects in humans. PMID:19181366

  7. [Migration and transformation of anthropogenic platinum group elements in environment: a review].

    PubMed

    Li, Pei-Miao; Gao, Xue-Lu

    2012-12-01

    Anthropogenic platinum group elements (PGEs) are widely applied in vehicle exhaust catalytic converters (VECs), industrial catalysts, and pharmaceutics, making the PGEs, especially Pt, Pd, and Rh, become the newly environmental pollutants in some fields. Given the positive correlations between the Pt/Pd and Pt/Rh ratios in various environmental samples and the active components of VECs, the VECs containing PGEs as catalysts are regarded as the primary source of PGEs pollution. Sufficient reports indicated that in the past three decades, there was a significant increase of PGEs concentrations in diverse environmental matrices like airborne particulate matters, aquatic ecosystem components (e.g., river water, rain water, groundwater, seawater, and sediments), soils, road dusts, and organisms. It was generally assumed that anthropogenic PGEs behave in inert manner, and the health risks associated with the environmental exposures to PGEs are minimal. However, the recent studies on PGEs toxicity and environmental bioavailability indicated that once entering environment, anthropogenic PGEs might easily be mobilized and transformed into more toxic forms under the actions of various biogeochemical processes, and thereby, enhanced their bioavailability and posed potential health risks to human beings through food chain. This paper summarized the research results about the sources, distribution, and biogeochemical behaviors of PGEs in various environmental media, and it was considered that to establish the standards of PGEs for human health risks, to develop standard substances of PGEs for environmental measurements, to study the PGEs in the sediments of marginal seas, and to assess the toxicity of PGEs to marine mollusks, the present contamination status of PGEs in foods, and the risks of PGEs to human health would be the hot research topics in the future. PMID:23479898

  8. Accumulating characteristics of platinum group elements (PGE) in urban environments, China.

    PubMed

    Pan, Suhong; Zhang, Gan; Sun, Yali; Chakraborty, Paromita

    2009-07-01

    The three-way catalytic converters [mainly using platinum, palladium and rhodium of platinum group elements (PGE)] have been widely used to reduce the pollution arising from vehicular traffic. Since the late 1990s, the Chinese government has implemented measures for new vehicles, equipped with the three-way catalytic converters in metropolitan cities. However, the PGE spreading on environments has not been strongly concerned in developing countries. This study investigated the accumulation characteristics of PGE in urban environments in China. A few samples from India were also analyzed and compared with those from China. The collected soil, aerosol and plant samples were determined for PGE by inductively coupled plasma-mass spectrometry (ICP-MS) after nickel sulphide fire assay preconcentration. The results have shown higher PGE contents in the samples from the cities where vehicles were fitted with autocatalysts for longer time periods. The highest values are 160 ng/g for Pt, 107 ng/g for Pd and 34.5 ng/g for Rh in Hong Kong soils, whereas the lowest values are 2.59 ng/g for Pt, 1.31 ng/g for Pd and 0.40 ng/g for Rh in Kolkata soils. In Beijing and Guangzhou aerosol samples, the PGE concentrations are 6.22 to 24.3 pg/m(3) for Pt and 1.16 to 8.60 pg/m(3) for Rh and 7.68 to 12.2 pg/m(3) for Pt and 2.15 to 5.15 pg/m(3) for Rh, respectively. The levels of PGE abundances in the urban environments of China have been significantly elevated with increasing number of vehicles equipped with autocatalysts. PMID:19410274

  9. Correlation between stretching mode absorptions and asymmetry of the V(O 2) group in peroxo complexes of vanadium (V)

    NASA Astrophysics Data System (ADS)

    Schwendt, P.; Volka, K.; Suchánek, M.

    Stretching vibration wavenumbers have been estimated for (NH 4) 2[VO(O 2) 2F] and (NH 4) 3[VO(O 2) 2F 2] based on normal coordinate calculations employing a valence force field derived from bond length—force constant correlations. The results bear out the recently suggested re-assignment of the vanadium—ligand stretching vibrations. The effect of ligands on the asymmetry of the ? group is discussed using structural data for 19 vanadium (V) peroxo complexes. The asymmetry of the ? group is different in compounds with different coordination numbers. This difference is accompanied by characteristic shifts of the vanadium—peroxo oxygen stretching mode absorptions.

  10. Re-Os isotopic systematics and platinum group element composition of the Tagish Lake carbonaceous chondrite

    Microsoft Academic Search

    Alan D. Brandon; Munir Humayun; Igor S. Puchtel; Michael E. Zolensky

    2005-01-01

    The Tagish Lake meteorite is a primitive C2 chondrite that has undergone aqueous alteration shortly after formation of its parent body. Previous work indicates that if this type of material was part of a late veneer during terrestrial planetary accretion, it could provide a link between atmophile elements such as H, C, N and noble gases, and highly siderophile element

  11. Survey of chimeric IStron elements in bacterial genomes: multiple molecular symbioses between group I intron ribozymes and DNA transposons

    PubMed Central

    Tourasse, Nicolas J.; Stabell, Fredrik B.; Kolstø, Anne-Brit

    2014-01-01

    IStrons are chimeric genetic elements composed of a group I intron associated with an insertion sequence (IS). The group I intron is a catalytic RNA providing the IStron with self-splicing ability, which renders IStron insertions harmless to the host genome. The IS element is a DNA transposon conferring mobility, and thus allowing the IStron to spread in genomes. IStrons are therefore a striking example of a molecular symbiosis between unrelated genetic elements endowed with different functions. In this study, we have conducted the first comprehensive survey of IStrons in sequenced genomes that provides insights into the distribution, diversity, origin and evolution of IStrons. We show that IStrons have a restricted phylogenetic distribution limited to two bacterial phyla, the Firmicutes and the Fusobacteria. Nevertheless, diverse IStrons representing two major groups targeting different insertion site motifs were identified. This taken with the finding that while the intron components of all IStrons belong to the same structural class, they are fused to different IS families, indicates that multiple intron–IS symbioses have occurred during evolution. In addition, introns and IS elements related to those that were at the origin of IStrons were also identified. PMID:25324310

  12. Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites

    USGS Publications Warehouse

    Davies, M.E.; Abalakin, V.K.; Cross, C.A.; Duncombe, R.L.; Masursky, H.; Morando, B.; Owen, T.C.; Seidelmann, P.K.; Sinclair, A.T.; Wilkins, G.A.; Tjuflin, Y.S.

    1980-01-01

    This paper is the entire report of the IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites, including three annexes. Tables give the recemmended values for the directions of the north poles of rotation and the prime meridians of the planets and satellites. Reference surfaces for mapping these bodies are described. The annexes discuss the guiding principles, given in the body of the report, present explanatory notes, and provide a bibliography of the rotational elements and reference surfaces of the planets and satellites, definitions, and algebraic expressions of relevant parameters. ?? 1980 D. Reidel Publishing Co.

  13. Superconductivity in quaternary niobium oxynitrides containing main group elements (M=Mg, Al, Si)

    SciTech Connect

    Ohashi, Y. [Faculty of Engineering, Hokkaido University, N13W8, Kita-ku, Sapporo 060-8628 (Japan); Kikkawa, S., E-mail: kikkawa@eng.hokudai.ac.jp [Faculty of Engineering, Hokkaido University, N13W8, Kita-ku, Sapporo 060-8628 (Japan); Felner, I.; Tsindlekht, M.I. [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Venkateshwarlu, D.; Ganesan, V. [UGC-DAE-Consortium for Scientific Research, Khandwa Rd, Indore (MP) 452001 (India); Yakhmi, J.V. [Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-04-15

    Niobium compounds continue to be an interesting family of superconductors, with the recent addition of oxynitrides to it, which can be categorized as low-T{sub c} superconductors (LTS) because they exhibit superconductivity below T{sub c}{approx}17 K. In this paper, we report the superconducting properties of three members of the family of niobium oxynitrides, viz. (Nb{sub 0.89}Al{sub 0.11})(N{sub 0.84}O{sub 0.16}), (Nb{sub 0.95}Mg{sub 0.05})(N{sub 0.92}O{sub 0.08}) and (Nb{sub 0.87}Si{sub 0.09}{open_square}{sub 0.04})(N{sub 0.87}O{sub 0.13}). Low temperature dc and ac magnetization measurements have been performed. In addition, heat capacity has been recorded at low temperature under applied magnetic fields. A detailed analysis of the data is presented. - Graphical abstract: The doped Si oxide accompanied with some amount of cation vacancy in cubic NbN lattice induces relatively large magnetic hysteresis on isothermal hysteresis loops at 5 K of the dc magnetization up to 5 T among the four niobium oxynitrides containing main group elements, Nb{sub 1.00}(N{sub 0.98}O{sub 0.02}); (Nb{sub 0.95}Mg{sub 0.05})(N{sub 0.92}O{sub 0.08}); (Nb{sub 0.89}Al{sub 0.11})(N{sub 0.84}O{sub 0.16}), and (Nb{sub 0.87}Si{sub 0.09}{open_square}{sub 0.04})(N{sub 0.87}O{sub 0.13}). Highlights: Black-Right-Pointing-Pointer Three Nb-oxynitrides doped either with Si, Al, Mg were bulk superconductors below {approx}17 K. Black-Right-Pointing-Pointer The cation vacancies induced by doping silicon act as pinning centers. Black-Right-Pointing-Pointer The Si-doped sample had strong electron correlations.

  14. Mobility of rhenium, platinum group elements and organic carbon during black shale weathering

    NASA Astrophysics Data System (ADS)

    Jaffe, Lillie A.; Peucker-Ehrenbrink, Bernhard; Petsch, Steven T.

    2002-05-01

    This study investigates the effects of black shale weathering on the Re-Os isotope system, platinum group element concentrations and the degradation of organic matter. Samples from a weathering profile in Late Devonian (˜365 Myr) Ohio Shale show a pronounced decrease (˜77%) in organic carbon (C org) near the present soil surface, relative to the interior portion of the outcrop. A similar trend is observed for total N (˜67% loss). Conversely, organic phosphorus (P org) concentrations increase by ˜59% near the soil surface. The decrease in C org is accompanied by a pronounced decrease in Re (˜99%) and, to a lesser extent, Os (˜39%). Palladium and Pt do not appear to be significantly mobile. The effects of Re and Os mobility on the Re-Os isotope system are significant: none of the samples plots on a 365 Myr isochron. Rather, the samples define a trend with a slope corresponding to an age of ˜18 Myr with an initial 187Os/ 188Os of ˜6.1. This indicates recent disturbance of the Re-Os system. Isotope mass balance calculations imply that the labile fraction of Os is significantly more radiogenic ( 187Os/ 188Os of ˜7.8) than the average of the unweathered samples ( 187Os/ 188Os of ˜6.4). Based on data from this study, the molar ratio of labile Re to C org in Ohio Shale is estimated at 7×10 -8. We estimate the present-day riverine, black shale-derived Re flux to seawater using literature data on Re burial in anoxic marine sediments, and assuming steady-state between Re release during black shale weathering and Re burial in anoxic marine sediments. Then, the labile Re/C org observed in this study implies that ˜0.5 Tmol of C org is released annually from weathering of black shales, a trace lithology in the continental crust. This flux corresponds to ˜12% of the estimated annual CO 2 flux from oxidative weathering of sedimentary rocks. The labile molar Re/Os of ˜270 indicates that black shale weathering releases ˜130 mol Os per year, which accounts for ˜7% of the riverine Os input to seawater. The data from this study support the notion that the crustal cycles of labile C org, Re and Os are tightly coupled. Gray shales, which are less C org-, Re- and Os-rich, but much more abundant in the continental crust than black shales, are likely to be even more important continental sources of Re and Os to seawater.

  15. Molecular and immunological characterization of group V allergen isoforms from velvet grass pollen (Holcus lanatus).

    PubMed

    Schramm, G; Bufe, A; Petersen, A; Schlaak, M; Becker, W M

    1998-03-01

    Group V grass pollen allergens belong to the major grass pollen allergens causing reactions of type I allergy. cDNAs coding for two isoforms of the group V allergen of velvet grass pollen (Holcus lanatus), a widespread grass species, were isolated from a cDNA library by hybridization with a 5'-terminal reverse-transcribed PCR-derived cDNA probe. Amino acid sequences of the two isoforms, designated rHol l 5.01 and rHol l 5.02, revealed high similarity between them (78% identity) and to group V allergens and their isoforms found in other grass species. Recombinant Hol l 5 isoforms were expressed in Escherichia coli and purified as fusion proteins. To compare their immunological reactivities with group-V-specific monoclonal antibodies and patients' IgE, immunoblotting, ELISA and histamine release assay were performed. Interestingly, monoclonal antibody Bo9, specific for group Vb isoforms of timothy grass, bound only to isoform rHol l 5.01, not to rHol l 5.02. On the other side, IgE reactivities of patients' sera revealed no differences between the two isoforms when investigated by immunoblotting and only slight differences when investigated by ELISA. In histamine release assay both isoforms released comparable amounts of histamine from basophils of four individual patients. Thus, the two group V isoforms of velvet grass pollen exhibit differential binding when tested with monoclonal antibodies, i.e. different structure of single epitopes, but negligible differences concerning overall IgE-binding capacity and histamine-releasing capacity. PMID:9523689

  16. Les Houches 2011: Physics at TeV Colliders New Physics Working Group Report

    E-print Network

    G. Brooijmans; B. Gripaios; F. Moortgat; J. Santiago; P. Skands; D. Albornoz Vásquez; B. C. Allanach; A. Alloul; A. Arbey; A. Azatov; H. Baer; C. Balázs; A. Barr; L. Basso; M. Battaglia; P. Bechtle; G. Bélanger; A. Belyaev; K. Benslama; L. Bergström; A. Bharucha; C. Boehm; M. Bondarenko; O. Bondu; E. Boos; F. Boudjema; T. Bringmann; M. Brown; V. Bunichev; S. Calvet; M. Campanelli; A. Carmona; D. G. Cerdeño; M. Chala; R. S. Chivukula; D. Chowdhury; N. D. Christensen; M. Cirelli; S. Cox; K. Cranmer; J. Da Silva; T. Delahaye; A. De Roeck; A. Djouadi; E. Dobson; M. Dolan; F. Donato; G. Drieu La Rochelle; G. Duda; C. Duhr; B. Dumont; J. Edsjö; J. Ellis; C. Evoli; A. Falkowski; M. Felcini; B. Fuks; E. Gabrielli; D. Gaggero; S. Gascon-Shotkin; D. K. Ghosh; A. Giammanco; R. M. Godbole; P. Gondolo; T. Goto; D. Grasso; P. Gris; D. Guadagnoli; J. F. Gunion; U. Haisch; L. Hartgring; S. Heinemeyer; M. Hirsch; J. Hewett; A. Ismail; T. Jeltema; M. Kadastik; M. Kakizaki; K. Kannike; S. Khalil; J-L. Kneur; M. Krämer; S. Kraml; S. Kreiss; J. Lavalle; R. Leane; J. Lykken; L. Maccione; F. Mahmoudi; M. Mangano; S. P. Martin; D. Maurin; G. Moreau; S. Moretti; I. Moskalenko; G. Moultaka; M. Muhlleitner; I. Niessen; B. O'Leary; E. Orlando; P. Panci; G. Polesello; W. Porod; T. Porter; S. Profumo; H. Prosper; A. Pukhov; A. Racioppi; M. Raidal; M. Rausch de Traubenberg; A. Renaud; J. Reuter; T. G. Rizzo; T. Robens; A. Y. Rodríguez-Marrero; P. Salati; C. Savage; P. Scott; S. Sekmen; A. Semenov; C. -L. Shan; C. Shepherd-Themistocleous; E. H. Simmons; P. Slavich; C. Speckner; F. Staub; A. Strong; R. Taillet; F. S. Thomas; M. C. Thomas; I. Tomalin; M. Tytgat; M. Ughetto; L. Valéry; D. G. E. Walker; A. Weiler; S. M. West; C. D. White; A. J. Williams; A. Wingerter; C. Wymant; J. -H. Yu; C. -P. Yuan; D. Zerwas

    2012-04-20

    We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our report includes new agreements on formats for interfaces between computational tools, new tool developments, important signatures for searches at the LHC, recommendations for presentation of LHC search results, as well as additional phenomenological studies.

  17. cond-mat/9704105v229Jan1998 LATTICE COLOR GROUPS OF QUASICRYSTALS

    E-print Network

    Lifshitz, Ron

    cond-mat/9704105v229Jan1998 LATTICE COLOR GROUPS OF QUASICRYSTALS RON LIFSHITZ Condensed Matter a translation, but this is in general not the case for quasicrystals. The key to redefining symmetry numbers of colors in a symmetric partitioning of a 2-dimensional N-fold quasicrystal. The sublattices

  18. CHILD SUPPORT PAID (Tracking Group V3) Student's Name: ____________________ SS#: ____________ CUNYFIRST ID#: ___________

    E-print Network

    Rosen, Jay

    CHILD SUPPORT PAID (Tracking Group V3) Student's Name: ____________________ SS or the student/spouse paid child support in 2012. List below the names of the persons who paid the child support, the names of the persons to whom the child support was paid, the names of the children for whom the child

  19. Layered V-B-O polyoxometalate nets linked by diethylenetriamine complexes with dangling amine groups.

    PubMed

    Chen, Hong; Zhang, Yunfeng; Yu, Zheng-Bao; Sun, Junliang

    2014-11-01

    Two layered V-B-O contained polyoxometalate (POM) net structures, denoted as SUT-12 and SUT-13, are reported here. SUT-12 was synthesized by the boric acid flux method, and it represents the first 2D structure constructed from the V6B20 vanadoborate cluster. SUT-13 was synthesized by the hydrothermal method and constructed from V12B6P12 vanadium borophosphate clusters. In both structures, the vanadoborate or vanadium borophosphate clusters were linked through in situ formed Zn(DETA)2 or Cu(DETA)2 complexes. Surprisingly, for all DETA molecules in the two metal complexes, there is one dangling amine group when it is coordinated to the metal. The phenomenon of the dangling amine group feature is abnormal and the Cu(DETA)2 complexes in SUT-13 were taken as an example and studied by the density functional theory (DFT) calculations in order to understand this unusual feature. PMID:25182271

  20. Minor/major element variation within and among diogenite and howardite orthopyroxenite groups

    NASA Technical Reports Server (NTRS)

    Berkley, John L.; Boynton, Nancy J.

    1992-01-01

    Diogenites are orthopyroxenites that may contain chromite and olivine as accessory minerals. Howardite breccias contain orthopyroxenite clasts with similar properties compared to monomict diogenites. We used statistical methods and variation plots of major and minor elements in orthopyroxene and chromite to show whether or not howardite orthopyroxenites are related to monomict diogenites, and to assess their petrogenesis. Our results fail to establish any evidence that monomict diogenites are significantly different from howardite orthopyroxenites in terms of major and minor elements. We also found no differences between Antarctic diogenites and non-Antarctic diogenites. Although element variation plots show compelling evidence that most diogenites originated by igneous fractionation, linear trends among the various diogenites and howardite orthopyroxenite clasts are either non-existent or ill-defined. This militates against an origin from a single magma body, but suggests an origin from multiple magma bodies in the parent planetoid.

  1. Platinum-group element distribution in the Main Zone and Upper Zone of the Bushveld Complex, South Africa

    Microsoft Academic Search

    Sarah-Jane Barnes; W. D Maier; L. D Ashwal

    2004-01-01

    The platinum-group element (PGE) contents of the upper portions of the Bushveld Complex were investigated with three questions in mind: (a) In natural systems does magnetite concentrate Os, Ir, Ru and Rh (IPGE), as has been observed in experimental systems? (b) Is there a Au–Pd-enriched layer present such as observed in the upper parts of the Skaergaard intrusion? (c) Can

  2. Determination of Platinum-Group Elements (PGE) from catalytic converters in soil by means of docimasy and INAA

    Microsoft Academic Search

    E. Heinrich; G. Schmidt; K.-L. Kratz

    1996-01-01

    The nickelsulfide fire assay (docimasy) for the enrichment of platinum-group elements (PGEs) has been modified for the use with small samples and combined with instrumental neutron-activation analysis (INAA). This procedure has been applied to the determination of PGEs exhausted from catalytic converters and deposited in soil near the Wiesbadener Kreuz (highway A3, Frankfurt-Köln). Our results show a considerable enhancement of

  3. Osmium isotopic compositions of Os-rich platinum group element alloys from the Klamath and Siskiyou Mountains

    Microsoft Academic Search

    Anders Meibom; Robert Frei; Norman H. Sleep

    2004-01-01

    We present new measurements of 186Os\\/188Os and 187Os\\/188Os in 10 Os-rich platinum group element (PGE) alloys from placer deposits formed by the mechanical erosion of peridotite-bearing ophiolites in the Klamath and Siskiyou Mountains in northern California and southwestern Oregon. These data nearly double our database of high-precision 186Os\\/188Os measurements on such samples. Together with previously published data, our new results

  4. Group 15 element–graphite composites synthesized by reduction of chlorides by KC 8: Characterization and electrochemical lithiation

    Microsoft Academic Search

    A. Dailly; L. Balan; J. Ghanbaja; P. Willmann; D. Billaud

    2005-01-01

    Group 15 element–graphite M\\/C composites were prepared by reduction of MClx chlorides (AsCl3, SbCl5, BiCl3) by KC8 in THF. Arsenic and antimony were both amorphous: antimony appeared as a film-like material, formed of aggregated nano-sized particles covering parts of the graphite surface; arsenic was present as large graphite supported particles. On the contrary, bismuth was present as crystalline metal nanoparticles

  5. Blue photo- and electroluminescence of silicon dioxide layers ion-implanted with group IV elements

    Microsoft Academic Search

    L. Rebohle; J. von Borany; H. Fröb; W. Skorupa

    2000-01-01

    .   The microstructural, optical and electrical properties of Si-, Ge- and Sn-implanted silicon dioxide layers were investigated.\\u000a It was found, that these layers exhibit strong photoluminescence (PL) around 2.7 eV (Si) and between 3 and 3.2 eV (Ge, Sn)\\u000a at room temperature (RT), which is accompanied by an UV emission around 4.3 eV. This PL is compared with that of Ar-implanted\\u000a silicon dioxide

  6. 75 FR 29531 - Resale Power Group of Iowa, WPPI Energy v. ITC Midwest LLC, Interstate Power and Light Company...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-26

    ...EL10-68-000] Resale Power Group of Iowa, WPPI Energy v...Interstate Power and Light Company; Notice of Complaint May...2006), Resale Power Group of Iowa and WPPI Energy...Interstate Power and Light Company (Respondents),...

  7. Utilizing Prestructured Art Elements in Brief Group Art Therapy with Adolescents.

    ERIC Educational Resources Information Center

    Vick, Randy M.

    1999-01-01

    A decrease in the average stay in mental health programs has changed the delivery of art therapy services. Article presents strategies for utilizing six prestructured art elements (magazine pictures, magazine words, photocopied images, cut and torn paper, traced shapes, and partial drawings) as a means of addressing these trends. Treatment sources…

  8. Research papers Distribution of platinum-group and chalcophile elements in the Aguablanca NiCu

    E-print Network

    of these elements in the deposit. The BMS (pyrrhotite, pentlandite, chalcopyrite and minor pyrite) occur as semi-massive, disseminated and minor chalcopyrite-veined ores. On the basis of whole rock metal abundances and BMS mineralogy to minor Cu-rich sulfide liquid in the form of chalcopyrite veinlets with relatively Pd-, Au- and Ag

  9. JV Task 94 - Air Quality V: Mercury, Trace Elements, SO3, and Particulate Matter Conference

    SciTech Connect

    Thomas A. Erickson

    2007-01-31

    This final report summarizes the planning, preparation, facilitation and production, and summary of the conference entitled 'Air Quality V: Mercury, Trace Elements, SO{sub 3}, and Particulate Matter,' held September 18-21, 2005, in Arlington, Virginia. The goal of the conference was to build on the discussions of the first four Air Quality Conferences, providing further opportunity for leading representatives of industry, government, research institutions, academia, and environmental organizations to discuss the key interrelationships between policy and science shaping near-term regulations and controls and to assist in moving forward on emerging issues that will lead to acceptable programs and policies to protect human health, the environment, and economic growth. The conference was extremely timely, as it was the last large conference prior to publication of the U.S. Environmental Protection Agency's final regulations for mercury control from coal-fired utilities, and provided a forum to realistically assess the status of mercury controls in relation to the new regulations.

  10. Finite Element Simulation of Machining of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Rizzuti, S.; Umbrello, D.

    2011-05-01

    Titanium and its alloys are an important class of materials, especially for aerospace applications, due to their excellent combination of strength and fracture toughness as well as low density. However, these materials are generally regarded as difficult to machine because of their low thermal conductivity and high chemical reactivity with cutting tool materials. Moreover, the low thermal conductivity of Titanium inhibits dissipation of heat within the workpiece causing an higher temperature at the cutting edge and generating for higher cutting speed a rapid chipping at the cutting edge which leads to catastrophic failure. In addition, chip morphology significantly influences the thermo-mechanical behaviour at the workpiece/tool interface, which also affects the tool life. In this paper a finite element analysis of machining of TiAl6V4 is presented. In particular, cutting force, chip morphology and segmentation are taken into account due to their predominant roles to determine machinability and tool wear during the machining of these alloys. Results in terms of residual stresses are also presented. Moreover, the numerical results are compared with experimental ones.

  11. Method of loading organic materials with group III plus lanthanide and actinide elements

    DOEpatents

    Bell, Zane W. (Oak Ridge, TN); Huei-Ho, Chuen (Oak Ridge, TN); Brown, Gilbert M. (Knoxville, TN); Hurlbut, Charles (Sweetwater, TX)

    2003-04-08

    Disclosed is a composition of matter comprising a tributyl phosphate complex of a group 3, lanthanide, actinide, or group 13 salt in an organic carrier and a method of making the complex. These materials are suitable for use in solid or liquid organic scintillators, as in x-ray absorption standards, x-ray fluorescence standards, and neutron detector calibration standards.

  12. arXiv:1312.6930v1[math.RT]25Dec2013 MYSTIC REFLECTION GROUPS

    E-print Network

    Berenstein, Arkady

    arXiv:1312.6930v1[math.RT]25Dec2013 MYSTIC REFLECTION GROUPS YURI BAZLOV AND ARKADY BERENSTEIN To the memory of Andrei Zelevinsky Abstract. This paper aims to systematically study mystic reflection groups to a group G satisfying (a) and (b) above as mystic reflection group. Independently, in [1] we solved

  13. First principles calculation of material properties of group IV elements and III-V compounds

    E-print Network

    Malone, Brad Dean

    2012-01-01

    forms of silicon: amorphous, polycrystalline, and the cubicfor silicon in the amorphous (a Si), polycrystalline (polysilicon commonly used in photovoltaic de- vices, namely the cubic, polycrystalline, and

  14. Bismuth nano-droplets for group-V based molecular-beam droplet epitaxy

    SciTech Connect

    Li, C.; Zeng, Z. Q.; Hirono, Y.; Morgan, T. A.; Hu, X.; Salamo, G. J. [Arkansas Institute for Nanoscale Material Science and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Fan, D. S.; Wu, J.; Yu, S. Q. [Arkansas Institute for Nanoscale Material Science and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Wang, Zh. M. [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2011-12-12

    Self-assembly of bismuth droplets at nanoscale on GaAs(100) surface using molecular beam epitaxy was demonstrated. Fine control of density and size was achieved by varying growth temperature and total bismuth deposition. Droplet density was tuned by roughly 3 orders of magnitude, and the density-temperature dependence was found to be consistent with classical nucleation theory. These results may extend the flexibility of droplet epitaxy by serving as templates for group V based droplet epitaxy, which is in contrast to conventional group III based droplet epitaxy and may encourage nanostructure formation of bismuth-containing materials.

  15. A group of scs elements function as domain boundaries in an enhancer-blocking assay.

    PubMed Central

    Kellum, R; Schedl, P

    1992-01-01

    Chromosomes of higher eukaryotes are thought to be organized into a series of discrete and topologically independent higher-order domains. In addition to providing a mechanism for chromatin compaction, these higher-order domains are thought to define independent units of gene activity. Implicit in most models for the folding of the chromatin fiber are special nucleoprotein structures, the domain boundaries, which serve to delimit each higher-order chromosomal domain. We have used an "enhancer-blocking assay" to test putative domain boundaries for boundary function in vivo. This assay is based on the notion that in delimiting independent units of gene activity, domain boundaries should be able to restrict the scope of activity of enhancer elements to genes which reside within the same domain. In this case, interposing a boundary between an enhancer and a promoter should block the action of the enhancer. In the experiments reported here, we have used the yolk protein-1 enhancer element and an hsp70 promoter:lacZ fusion gene to test putative boundary DNA segments for enhancer-blocking activity. We have found that several scs-like elements are capable of blocking the action of the yp-1 enhancer when placed between it and the hsp70 promoter. In contrast, a MAR/SAR DNA segment and another spacer DNA segment had no apparent effect on enhancer activity. Images PMID:1569958

  16. Final Report: Main Group Element Chemistry in Service of Hydrogen Storage and Activation

    SciTech Connect

    David A. Dixon; Anthony J. Arduengo, III

    2010-09-30

    Replacing combustion of carbon-based fuels with alternative energy sources that have minimal environmental impact is one of the grand scientific and technological challenges of the early 21st century. Not only is it critical to capture energy from new, renewable sources, it is also necessary to store the captured energy efficiently and effectively for use at the point of service when and where it is needed, which may not be collocated with the collection site. There are many potential storage media but we focus on the storage of energy in chemical bonds. It is more efficient to store energy on a per weight basis in chemical bonds. This is because it is hard to pack electrons into small volumes with low weight without the use of chemical bonds. The focus of the project was the development of new chemistries to enable DOE to meet its technical objectives for hydrogen storage using chemical hydrogen storage systems. We provided computational chemistry support in terms of thermodynamics, kinetics, and properties prediction in support of the experimental efforts of the DOE Center of Excellence for Chemical Hydrogen Storage. The goal of the Center is to store energy in chemical bonds involving hydrogen atoms. Once the hydrogen is stored in a set of X-H/Y-H bonds, the hydrogen has to be easily released and the depleted fuel regenerated very efficiently. This differs substantially from our current use of fossil fuel energy sources where the reactant is converted to energy plus CO2 (coal) or CO2 and H2O (gasoline, natural gas), which are released into the atmosphere. In future energy storage scenarios, the spent fuel will be captured and the energy storage medium regenerated. This places substantial additional constraints on the chemistry. The goal of the computational chemistry work was to reduce the time to design new materials and develop materials that meet the 2010 and 2015 DOE objectives in terms of weight percent, volume, release time, and regeneration ability. This goal was met in terms of reducing the number of costly experiments and helping to focus the experimental effort on the potentially optimal targets. We have used computational chemistry approaches to predict the thermodynamic properties of a wide range of compounds containing boron, nitrogen, hydrogen, and other elements as appropriate including carbon. These calculations were done in most cases with high level molecular orbital theory methods that have small error bars on the order of ± 1 to 2 kcal/mol. The results were used to benchmark more approximate methods such as density functional theory for larger systems and for database development. We predicted reliable thermodynamics for thousands of compounds for release and regeneration schemes to aid/guide materials design and process design and simulation. These are the first reliable computed values for these compounds and for many represent the only available values. Overall, the computational results have provided us with new insights into the chemistry of main group and organic-base chemical hydrogen systems from the release of hydrogen to the regeneration of spent fuel. A number of experimental accomplishments were also made in this project. The experimental work on hydrogen storage materials centered on activated polarized ?- or ?-bonded frameworks that hold the potential for ready dihydrogen activation, uptake, and eventually release. To this end, a large number of non-traditional valence systems including carbenes, cyanocarbons, and C-B and and B-N systems were synthesized and examined. During the course of these studies an important lead arose from the novel valency of a class of stable organic singlet bi-radical systems. A synthetic strategy to an “endless” hydrogen storage polymer has been developed based on our cyanocarbon chemistry. A key issue with the synthetic efforts was being able to link the kinetics of release with the size of the substituents as it was difficult to develop a low molecular weight molecule with the right kinetics. A novel hydrogen activation process has been developed

  17. The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG).

    PubMed

    Chen, Robert T; Carbery, Baevin; Mac, Lisa; Berns, Kenneth I; Chapman, Louisa; Condit, Richard C; Excler, Jean-Louis; Gurwith, Marc; Hendry, Michael; Khan, Arifa S; Khuri-Bulos, Najwa; Klug, Bettina; Robertson, James S; Seligman, Stephen J; Sheets, Rebecca; Williamson, Anna-Lise

    2015-01-01

    Recombinant viral vectors provide an effective means for heterologous antigen expression in vivo and thus represent promising platforms for developing novel vaccines against human pathogens from Ebola to tuberculosis. An increasing number of candidate viral vector vaccines are entering human clinical trials. The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to improve our ability to anticipate potential safety issues and meaningfully assess or interpret safety data, thereby facilitating greater public acceptance when licensed. PMID:25305565

  18. Process for forming shaped group III-V semiconductor nanocrystals, and product formed using process

    DOEpatents

    Alivisatos, A. Paul (Oakland, CA); Peng, Xiaogang (Fayetteville, AR); Manna, Liberato (Palo del Colle, IT)

    2001-01-01

    A process for the formation of shaped Group III-V semiconductor nanocrystals comprises contacting the semiconductor nanocrystal precursors with a liquid media comprising a binary mixture of phosphorus-containing organic surfactants capable of promoting the growth of either spherical semiconductor nanocrystals or rod-like semiconductor nanocrystals, whereby the shape of the semiconductor nanocrystals formed in said binary mixture of surfactants is controlled by adjusting the ratio of the surfactants in the binary mixture.

  19. Static and dynamical properties of II–VI and III–V group binary solids

    Microsoft Academic Search

    D S Yadav; D V Singh

    2012-01-01

    In this paper, we extend to II–VI and III–V group binary solids of zinc blende (ZB) structure with conduction d-electrons the calculation of static and dynamical properties such as bulk modulus (B) and cohesive energy or total energy (Ecoh) using the plasma oscillation theory of solids formalism already employed for ternary chalcopyrite semiconductors. The present method is not limited to

  20. Structural studies of III–V and group IV semiconductors at high pressure

    Microsoft Academic Search

    R. J. Nelmes; M. I. McMahon; N. G. Wright; D. R. Allan; H. Liu; J. S. Loveday

    1995-01-01

    Extensive new structural results on II–VI, III–V and group IV semiconductors under pressure have been obtained over the past two years at SRS Daresbury, using angle-dispersive techniques and an image-plate detector. In this paper, a brief overview is presented of recent work on Si, Ge, GaSb, InSb, InAs, InP and GaAs.

  1. Electrical and optical characterization of Group III-V heterostructures with emphasis on terahertz devices

    Microsoft Academic Search

    Aruna B. Weerasekara

    2007-01-01

    Electrical and optical characterizations of heterostructures and thin films based on group III-V compound semiconductors are presented. Optical properties of GaMnN thin films grown by Metalorganic Chemical Vapor Deposition (MOCVD) on GaN\\/Sapphire templates were investigated using IR reflection spectroscopy. Experimental reflection spectra were fitted using a non-linear fitting algorithm, and the high frequency dielectric constant (epsiloninfinity), optical phonon frequencies of

  2. Consensus recommendations for common data elements for operational stress research and surveillance: report of a federal interagency working group.

    PubMed

    Nash, William P; Vasterling, Jennifer; Ewing-Cobbs, Linda; Horn, Sarah; Gaskin, Thomas; Golden, John; Riley, William T; Bowles, Stephen V; Favret, James; Lester, Patricia; Koffman, Robert; Farnsworth, Laura C; Baker, Dewleen G

    2010-11-01

    Empirical studies and surveillance projects increasingly assess and address potentially adverse psychological health outcomes from the stress of military operations, but no standards yet exist for common concept definitions, variable categories, and measures. This article reports the consensus recommendations of the federal interagency Operational Stress Working Group for common data elements to be used in future operational stress research and surveillance with the goal of improving comparability across studies. Operational stress encompasses more than just combat; it occurs everywhere service members and their families live and work. Posttraumatic stress is not the only adverse mental or behavioral health outcome of importance. The Operational Stress Working Group contends that a primary goal of operational stress research and surveillance is to promote prevention of adverse mental and behavioral outcomes, especially by recognizing the preclinical and subclinical states of distress and dysfunction that portend a risk for failure of role performance or future mental disorders. Recommendations for data elements are divided into 3 tiers: core, supplemental, and emerging, including variable domains and specific measures for assessing operational stressor exposures, stress outcomes, moderating factors, and mediating processes. Attention is drawn to the emerging construct of stress injury as a generic term for subclinical operational stress, and to emerging data elements addressing biological, psychological, and spiritual mediators of risk. Methodologies are needed for identifying preclinical and subclinical states of distress or dysfunction that are markers of risk for failure of role performance and future clinical mental disorders, so that targeted prevention interventions can be developed and evaluated. PMID:21044711

  3. Group V trimers and their positive ions: The electronic structure and potential energy surfaces

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K.; Sumathi, K.; Dai, Dingguo

    1991-09-01

    Complete active space multiconfiguration self-consistent field (CAS-MCSCF) followed by multireference configuration interactions (MRCI) calculations are made on the electronic states of P3, As3, Sb3, Bi3 and all their positive ions. All group V trimers have Jahn-Teller distorted 2A2 ground states arising from the 2E`(D3h) state while the positive ions have 1A'1(D3h) equilateral-triangular ground states. For the neutral species, the 2B1 Jahn-Teller component was found to be nearly degenerate with the 2A2 component. Extensive studies on As3, Sb3, and Bi3 reveal the existence of 4A2, 4E', and 2E' (D3h) excited states which also undergo Jahn-Teller distortion. The binding energies and the ionization potentials (IP) of all group V trimers were computed and compared with known experimental data on some of these species. The IPs and the binding energies per atom of group V trimers were found to be significantly smaller than dimers thus exhibiting odd-even alternation in these properties. Our computations explain the dramatically different photofragmentation patterns for antimony and bismuth clusters observed by Geusic et al.

  4. Synthesis and properties of layered synthetic microstructure (LSM) dispersion elements for 62 eV (200A) to 1. 24 keV (10A) radiation. Final report

    SciTech Connect

    Barbee, T.W. Jr.

    1981-08-01

    The opportunities offered by engineered synthetic multilayer dispersion elements for x-rays have been recognized since the earliest days of x-ray diffraction analysis. In this paper, application of sputter deposition technology to the synthesis of Layered Synthetic Microstructure (LSMs) of sufficient quality for use as x-ray dispersion elements is discussed. It will be shown that high efficiency, controllable bandwidth dispersion elements, with d spacings varying from 15 A to 180 A, may be synthesized onto both mechanically stiff and flexible substrates. Multilayer component materials include tungsten, niobium, molybdenum, titanium, vanadium, and silicon layers separated by carbon layers. Experimental observations of peak reflectivity in first order, integrated reflectivity in first order, and diffraction performance at selected photon energies in the range, 100 to 15,000 eV, will be reported and compared to theory.

  5. X-ray attenuation cross sections for energies 100 eV to 100 keV and elements Z = 1 to Z = 92

    Microsoft Academic Search

    E. B. Saloman; J. H. Hubbell; J. H. Scofield

    1988-01-01

    This work presents for the energy range 0.1--100 keV the National Bureau of Standards (NBS) database of experimental x-ray attenuation coefficients (total absorption cross sections) and cross sections calculated using a relativistic Hartree--Slater model for the photoelectric cross section for all elements of atomic number Z = 1--92. The information is displayed in both tabular and graphical form. Also shown

  6. Isotope Anomalies in the Fe-group Elements in Meteorites and Connections to Nucleosynthesis in AGB Stars

    NASA Astrophysics Data System (ADS)

    Wasserburg, G. J.; Trippella, O.; Busso, M.

    2015-05-01

    We study the effects of neutron captures in AGB stars on “Fe-group” elements, with an emphasis on Cr, Fe, and Ni. These elements show anomalies in 54Cr, 58Fe, and 64Ni in solar system materials, which are commonly attributed to supernovae (SNe). However, as large fractions of the interstellar medium (ISM) were reprocessed in AGB stars, these elements were reprocessed, too. We calculate the effects of such reprocessing on Cr, Fe, and Ni through 1.5 {{M}? } and 3 {{M}? } AGB models, adopting solar and 1/3 solar metallicities. All cases produce excesses of 54Cr, 58Fe, and 64Ni, while the other isotopes are little altered; hence, the observations may be explained by AGB processing. The results are robust and not dependent on the detailed initial isotopic composition. Consequences for other “Fe group” elements are then explored. They include 50Ti excesses and some production of 46,47,49Ti. In many circumstellar condensates, Ti quantitatively reflects these effects of AGB neutron captures. Scatter in the data results from small variations (granularity) in the isotopic composition of the local ISM. For Si, the main effects are instead due to variations in the local ISM from different SN sources. The problem of Ca is discussed, particularly with regard to 48Ca. The measured data are usually represented assuming terrestrial values for 42Ca/44Ca. Materials processed in AGB stars or sources with variable initial 42Ca/44Ca ratios can give apparent 48Ca excesses/deficiencies, attributed to SNe. The broader issue of galactic chemical evolution is also discussed in view of the isotopic granularity in the ISM.

  7. Crystal Field Theory and the Angular Overlap Model Applied to Hydrides of Main Group Elements.

    ERIC Educational Resources Information Center

    Moore, E. A.

    1990-01-01

    Described is how crystal field theory and the angular overlap model can be applied to very simple molecules which can then be used to introduce such concepts as bonding orbitals, MO diagrams, and Walsh diagrams. The main-group compounds are used as examples and a switch to the transition metal complexes. (KR)

  8. Effects of chemical functional groups on elemental mercury adsorption on carbonaceous surfaces.

    PubMed

    Liu, Jing; Cheney, Marcos A; Wu, Fan; Li, Meng

    2011-02-15

    A systematic theoretical study using density functional theory is performed to provide molecular-level understanding of the effects of chemical functional groups on mercury adsorption on carbonaceous surfaces. The zigzag and armchair edges were used in modeling the carbonaceous surfaces to simulate different adsorption sites. The edge atoms on the upper side of the models are unsaturated to simulate active sites. All calculations (optimizations, energies, and frequencies) were made at B3PW91 density functional theory level, using RCEP60VDZ basis set for mercury and 6-31G(d) pople basis set for other atoms. The results indicate that the embedding of halogen atom can increase the activity of its neighboring site which in turn increases the adsorption capacity of the carbonaceous surface for Hg(0). The adsorption belongs to chemisorptions, which is in good agreement with the experimental results. For the effects of oxygen functional groups, lactone, carbonyl and semiquinone favor Hg(0) adsorption because they increase the neighboring site's activity for mercury adsorption. On the contrary, phenol and carboxyl functional groups show a physisorption of Hg(0), and reduce Hg capture. This result can explain the seemingly conflicting experimental results reported in the literature concerning the influence of oxygen functional groups on mercury adsorption on carbonaceous surface. PMID:21144653

  9. Which Social Elements Are Visible in Virtual Groups? Addressing the Categorization of Social Expressions

    ERIC Educational Resources Information Center

    Perez-Mateo, M.; Guitert, M.

    2012-01-01

    Learning is a social process. That is why it is extremely important to understand how students interact socially in online courses and how it affects the learning process. However, social aspects, understood as those expressions or comments that go beyond strictly academic interaction, i.e. the need to carry out group work, are not clearly…

  10. Banach frames in coorbit spaces consisting of elements which are invariant under symmetry groups

    E-print Network

    Feichtinger, Hans Georg

    the continuous transform. As examples, the continuous wavelet transform and the short time Fourier transform function on the positive halfline R+ and it turned out in [18] that the continuous wavelet transform representation theory of locally compact groups. In this abstract setting the theory for the continuous transform

  11. On the Solubility of Group IV Elements (Ti, Zr, Hf) in Liquid Aluminum Below 800C

    E-print Network

    Paris-Sud XI, Université de

    alloys, binary system, experimental tech- niques, liquidus 1. Introduction The alloying of Al with group phase diagrams, among Al-Ti, Al-Zr, and Al-Hf systems are characterized by the presence of a peritectic is also depleted in solute, and this--associated with the peritectic nature of the phase diagram

  12. Unipotent elements of finite groups of Lie type and realization fields of their complex representations

    Microsoft Academic Search

    Pham Huu Tiep

    2004-01-01

    Let p be a prime. This paper classifies finite connected reductive groups G in characteristic p with the property that all complex character values of G belong to an unramified above p extension of the field of rational numbers. The main application of these results is to the problem of describing the irreducible complex (or p-adic) representations of G that

  13. Distribution of the Platinum Group Elements in Peat Deposit Near a Historic Lead and Silver Mining District

    Microsoft Academic Search

    Ladislav Strnad; Martin Mihaljevi?; Vojt?ch Ettler; Linda Barsová; Milan Zuna; Ond?ej Šebek

    2008-01-01

    Concentrations of platinum group elements (PGE) and Ag were studied in a minerotrophic peat deposit near a historic Pb–Ag\\u000a mining district (P?íbram, Czech Republic). The PGE determinations were performed by quadrupole ICP-MS after NiS fire assay\\u000a procedure. In the individual peat layers (dated by measurement of 210Pb activity) the PGE concentrations were low and ranged from 0.015 ng g?1 (Ir) to 11.8 ng g?1

  14. Slope stability analysis by nite elements D. V. GRIFFITHS and P. A. LANE{

    E-print Network

    , regarding the failure mechanism. Slope failure in the ®nite element model occurs `naturally' through methods, including the in¯uence of a free surface on slope and dam stability. Graphical output is included to illustrate defor- mations and mechanisms of failure. It is argued that the ®nite element method of slope

  15. DC dissipation current from elements used for lightning protection on 115 kV transmission lines

    Microsoft Academic Search

    S. Grzybowski; A. L. Libby; E. B. Jenkins; C. R. Davis

    1991-01-01

    The Mississippi Power & Light Company is using different elements in transmission lines and towers to protect the electrical system from direct lightning strokes. According to some theories, the objects to be protected against lightning strokes are better protected by using an element from which the charge dissipation current is enhanced. The authors present the results of an experimental study

  16. Elastic scattering of 22.1keV photons by elements in the atomic region 12<=Z<=92

    Microsoft Academic Search

    J. S. Shahi; Sanjiv Puri; D. Mehta; M. L. Garg; Nirmal Singh; P. N. Trehan

    1997-01-01

    Differential cross sections for the elastic scattering of 22.1-keV photons by 30 elements in the atomic region 12<=Z<=92 have been measured at an angle of 117°. The measurements were performed under vacuum using Si(Li) detector and 109Cd radioisotope as photon source. The intensity of incident photons, detector efficiency, and other geometrical factors was determined by measuring the K x-ray yields

  17. Approximation Algorithms for Euclidean Group Khaled Elbassioni, Aleksei V. Fishkin, Nabil H. Mustafa, and Ren e Sitters

    E-print Network

    Elbassioni, Khaled

    Approximation Algorithms for Euclidean Group TSP Khaled Elbassioni, Aleksei V. Fishkin, Nabil H:felbassio,avf,nmustafa,sittersg@mpi-sb.mpg.de Abstract. In the Euclidean group Traveling Salesman Problem (TSP), we are given a set of points P with Neighborhoods and the Group Steiner Tree problem. We give a (9:1#11; + 1)-approximation algorithm for the case

  18. TOAFEW-V multigroup cross-section collapsing code and library of 154-group-processed ENDF\\/B\\/V fission-product and actinide cross sections

    Microsoft Academic Search

    W. B. Wilson; T. R. England; R. J. LaBauve; R. M. Boicourt

    1982-01-01

    The ENDF\\/B-V cross sections of 237 fission-product and actinide nuclides have been processed at infinite dilution into 154 neutron energy groups at temperatures of 300, 900, and 1200 K. Additional 154-group self-shielded actinide cross sections were calculated with Bondarenko background sigmaâ values as small as 1 barn. The production and content of the multigroup data library is described. The TOAFEW-V

  19. Trace element analysis of obsidian artifacts from a classic Maya residential group at Nohmul, Belize

    SciTech Connect

    Hammond, N.; Neivens, M.D.; Harbottle, G.

    1984-01-01

    Forty-nine obsidian artifacts from a classic period residential group at Nohmul, northern Belize, have been analyzed by neutron activation analysis. The majority of the samples originated from Ixtepeque, and the remainder from El Chayal. Increasing prominence of the Ixtepeque source from the late Classic into the Terminal Classic (i.e., before and after ca. A.D. 800) suggests greater use of a coastal distribution route known to have originated in the formative and to have remained in use through the colonial period.

  20. Elements of a new Global Water Strategy for the Group on Earth Observations

    NASA Astrophysics Data System (ADS)

    Lawford, Richard; Koike, Toshio; Ochiai, Osamu; Cripe, Douglas

    2013-04-01

    In order to address the need to review the scope and direction of GEO activities related to water and to provide guidance for the post-2015 GEO planning, the Integrated Global Water Cycle Observations (IGWCO) Community of Practice and the Committee on Earth Observation Satellites (CEOS) are working together to develop a strategy for GEO water activities over the next decade. This presentation will review the elements of the strategy which include topics as comprehensive as user needs and engagement, water cycle observational systems, assessment of water quality, data issues, interoperability and integration of water information systems and capacity building. Impediments in the flow of information and technological capabilities from the providers of new technologies, innovations and data products to the end users will be explored in terms of the nature of these impediments and how they can be overcome. To be successful in GEO's framework of volunteerism, the water strategy should build on activities that are on-going in related programmes at the international and national levels. In addition, implementation of the strategy will need to be supported through new initiatives and policies that promote greater integration. Suggestions for achieving these goals will be outlined at the end of the talk.

  1. Identification of Polycomb and Trithorax Group Responsive Elements in the Regulatory Region of the Drosophila Homeotic Gene Sex Combs Reduced

    PubMed Central

    Gindhart-Jr., J. G.; Kaufman, T. C.

    1995-01-01

    The Drosophila homeotic gene Sex combs reduced (Scr) is necessary for the establishment and maintenance of the morphological identity of the labial and prothoracic segments. In the early embryo, its expression pattern is established through the activity of several gap and segmentation gene products, as well as other transcription factors. Once established, the Polycomb group (Pc-G) and trithorax group (trx-G) gene products maintain the spatial pattern of Scr expression for the remainder of development. We report the identification of DNA fragments in the Scr regulatory region that may be important for its regulation by Polycomb and trithorax group gene products. When DNA fragments containing these regulatory sequences are subcloned into P-element vectors containing a white minigene, transformants containing these constructs exhibit mosaic patterns of pigmentation in the adult eye, indicating that white minigene expression is repressed in a clonally heritable manner. The size of pigmented and nonpigmented clones in the adult eye suggests that the event determining whether a cell in the eye anlagen will express white occurs at least as early as the first larval instar. The amount of white minigene repression is reduced in some Polycomb group mutants, whereas repression is enhanced in flies mutant for a subset of trithorax group loci. The repressor activity of one fragment, normally located in Scr Intron 2, is increased when it is able to homologously pair, a property consistent with genetic data suggesting that Scr exhibits transvection. Another Scr regulatory fragment, normally located 40 kb upstream of the Scr promoter, silences ectopic expression of an Scr-lacZ fusion gene in the embryo and does so in a Polycomb-dependent manner. We propose that the regulatory sequences located within these DNA fragments may normally mediate the regulation of Scr by proteins encoded by members of the Polycomb and trithorax group loci. PMID:7713433

  2. Irradiance and the elemental stoichiometry of marine phytoplankton Z. V. Finkel1 and A. Quigg2

    E-print Network

    composition (C, N, P, S, K, Mg, Ca, Sr, Fe, Mn, Zn, Cu, Co, Mo, and Ni) of five marine phytoplankton species reported differences associated with evolutionary history. We found that many elements (Fe, Mn, Zn, Cu, Co

  3. Nitric acid passivation of Ti6Al4V reduces thickness of surface oxide layer and increases trace element release.

    PubMed

    Callen, B W; Lowenberg, B F; Lugowski, S; Sodhi, R N; Davies, J E

    1995-03-01

    Passivation of Ti6Al4V and cpTi implants using methods based on the ASTM-F86 nitric acid protocol are used with the intention of reducing their surface reactivity, and consequently the corrosion potential, in the highly corrosive biologic milieu. The ASTM-F86 passivation protocol was originally developed for surgical implants made of stainless steel and chrome cobalt alloy. Using X-ray photoelectron spectroscopy (XPS) to examine the effect of nitric acid passivation on the surface oxide layer of mill-annealed Ti6Al4V and cpTi, we have found that such treatment actually reduced the oxide thickness on the alloy while having no significant effect on the pure metal. These results correlated with observations obtained using graphite furnace atomic absorption spectrophotometry (GFAAS) to detect trace element release from solid, mill-annealed, Ti6Al4V and cpTi into serum-containing culture medium. We detected significantly greater levels of Ti, Al, and V in the presence of passivated compared to nonpassivated Ti6Al4V. In contrast, nitric acid passivation did not influence Ti release from mill-annealed cpTi. These results, derived from two mill-annealed Ti-based metals, would indicate that re-examination of ASTM-F86-based passivation protocols with respect to Ti6Al4V should be considered in view of the widespread use of this alloy for biomedical devices. PMID:7615579

  4. CTCF-binding elements 1 and 2 in the Igh intergenic control region cooperatively regulate V(D)J recombination.

    PubMed

    Lin, Sherry G; Guo, Chunguang; Su, Arthur; Zhang, Yu; Alt, Frederick W

    2015-02-10

    Ig heavy chain (IgH) variable region exons are assembled from V, D, and J gene segments during early B-lymphocyte differentiation. A several megabase region at the "distal" end of the mouse IgH locus (Igh) contains hundreds of V(H)s, separated by an intergenic region from Igh Ds, J(H)s, and constant region exons. Diverse primary Igh repertoires are generated by joining Vs, Ds, and Js in different combinations, with a given B cell productively assembling only one combination. The intergenic control region 1 (IGCR1) in the V(H)-to-D intergenic region regulates Igh V(D)J recombination in the contexts of developmental order, lineage specificity, and feedback from productive rearrangements. IGCR1 also diversifies IgH repertoires by balancing proximal and distal V(H) use. IGCR1 functions in all these regulatory contexts by suppressing predominant rearrangement of D-proximal V(H)s. Such IGCR1 functions were neutralized by simultaneous mutation of two CCCTC-binding factor (CTCF)-binding elements (CBE1 and CBE2) within it. However, it was unknown whether only one CBE mediates IGCR1 functions or whether both function in this context. To address these questions, we generated mice in which either IGCR1 CBE1 or CBE2 was replaced with scrambled sequences that do not bind CTCF. We found that inactivation of CBE1 or CBE2 individually led to only partial impairment of various IGCR1 functions relative to the far greater effects of inactivating both binding elements simultaneously, demonstrating that they function cooperatively to achieve full IGCR1 regulatory activity. Based on these and other findings, we propose an orientation-specific looping model for synergistic CBE1 and CBE2 functions. PMID:25624508

  5. Abelian groups 

    E-print Network

    Bolen, James Cordell

    1956-01-01

    groups. In order to d. o this, we will need the aid. of some vector space theorys D~ef ~tp 4s10 A vector ~sac 7 over the field. P is an abelian group which admits mult1plicatlon by elements of t' he field. such that, for a, b e P and. x, y s V& (l) a(x... (antisymmetry), (c) x & y, y & z implies that x & z (transitivity). Let S be a partially ordered set and T a subset. Defin1tion 4s2 The element x is an ~u er bound. of T if x & y for every y in T. The element x may or may not be in T. Definition 4...

  6. Exploring cryogenic focused ion beam milling as a Group III-V device fabrication tool

    NASA Astrophysics Data System (ADS)

    Dolph, Melissa Commisso; Santeufemio, Christopher

    2014-06-01

    In this paper, we compare the features observed on a Group III-V strained layer superlattice (SLS) materials system as a result of room temperature Ga+ focused ion beam (FIB) milling to the features observed as a result of cryogenic FIB (cryo-FIB) milling at -135 °C under the same beam conditions (30 kV:1 nA). The features on the cryo-FIB milled material were observed both when the material was still cold and after it returned to room temperature. Although cryo-FIB milling yielded patterned features that were initially cleaner than comparable features defined by FIB milling at room temperature, we found that both room temperature FIB milling and cryo-FIB milling with subsequent sample warm-up resulted in the formation of Group III enriched features. These findings suggest that the structural and chemical properties of features fabricated by cryo-FIB milling are temperature-dependent, which is an important consideration when it comes to device fabrication. These dependencies will need to be better understood and controlled if cryo-FIB milling is to have future applications in this area.

  7. Conserved Target for Group II Intron Insertion in Relaxase Genes of Conjugative Elements of Gram-Positive Bacteria

    PubMed Central

    Staddon, Jack H.; Bryan, Edward M.; Manias, Dawn A.; Dunny, Gary M.

    2004-01-01

    The lactococcal group II intron Ll.ltrB interrupts the ltrB relaxase gene within a region that encodes a conserved functional domain. Nucleotides essential for the homing of Ll.ltrB into an intronless version of ltrB are found exclusively at positions required to encode amino acids broadly conserved in a family of relaxase proteins of gram-positive bacteria. Two of these relaxase genes, pcfG from the enterococcal plasmid pCF10 and the ORF4 gene in the streptococcal conjugative transposon Tn5252, were shown to support Ll.ltrB insertion into the conserved motif at precisely the site predicted by sequence homology with ltrB. Insertion occurred through a mechanism indistinguishable from retrohoming. Splicing and retention of conjugative function was demonstrated for pCF10 derivatives containing intron insertions. Ll.ltrB targeting of a conserved motif of a conjugative element suggests a mechanism for group II intron dispersal among bacteria. Additional support for this mechanism comes from sequence analysis of the insertion sites of the E.c.I4 family of bacterial group II introns. PMID:15060042

  8. Role of group V exchange on the shape and size of InAs\\/InP self-assembled nanostructures

    Microsoft Academic Search

    H. R. Gutie´rrez; M. A. Cotta; J. R. R. Bortoleto; M. M. G. de Carvalho

    2002-01-01

    We have studied the influence of Group V overpressure on the final shape and size of InAs nanostructures grown on (001) InP substrates. The mechanisms leading to postgrowth modifications in the InAs nanostructures are discussed. The simultaneous action of Group V overpressure and stress field—produced by the InAs nanostructures—can induce strong material transport. The direction of this material net current

  9. Role of group V exchange on the shape and size of InAs\\/InP self-assembled nanostructures

    Microsoft Academic Search

    H. R. Gutiérrez; M. A. Cotta; J. R. R. Bortoleto; M. M. G. de Carvalho

    2002-01-01

    We have studied the influence of Group V overpressure on the final shape and size of InAs nanostructures grown on (001) InP substrates. The mechanisms leading to postgrowth modifications in the InAs nanostructures are discussed. The simultaneous action of Group V overpressure and stress field-produced by the InAs nanostructures-can induce strong material transport. The direction of this material net current

  10. Platinum-group elements in rocks from the voikar-syninsky ophiolite complex, Polar Urals, U.S.S.R.

    USGS Publications Warehouse

    Page, N.J.; Aruscavage, P. J.; Haffty, J.

    1983-01-01

    Analyses of platinum-group elements (PGE) in rocks collected from the Voikar-Syninsky ophiolite in the Polar Urals suggest that the distribution and geochemistry of PGE in this Paleozoic ophiolite are similar to those in Mesozoic ophiolites from elsewhere. Chondrite-normalized PGE patterns for chromitite, the tectonite unit, and ultramafic and mafic cumulate unit have negative slopes. These results are similar to those found for chromitites from other ophiolites; stratiform chromities show positive slopes. If the magmas that form both types of chromitite originate from similar mantle source material with respect to PGE content, the processes involved must be quite different. However, the distinct chondrite-normalized PGE patterns may reflect differing source materials. ?? 1983 Springer-Verlag.

  11. Distribution of the platinum group elements in peat deposit near a historic lead and silver mining district.

    PubMed

    Strnad, Ladislav; Mihaljevic, Martin; Ettler, Vojtech; Barsová, Linda; Zuna, Milan; Sebek, Ondrej

    2008-08-01

    Concentrations of platinum group elements (PGE) and Ag were studied in a minerotrophic peat deposit near a historic Pb-Ag mining district (Príbram, Czech Republic). The PGE determinations were performed by quadrupole ICP-MS after NiS fire assay procedure. In the individual peat layers (dated by measurement of (210)Pb activity) the PGE concentrations were low and ranged from 0.015 ng g(-1) (Ir) to 11.8 ng g(-1) (Pt). The enrichment of PGE (especially Pt) compared to the Earth crust contents were observed during two periods. The peak in the second half of 19th century was explained by massive increase of ore mining and affinity of PGE to concentrate in molten lead during Pb processing. The recent PGE enrichment in peat layers might be explained by automobile (with catalytic converters) exhaust fumes or processing of computer electronic parts by the smelter. PMID:18373043

  12. Element distribution patterns in the ordovician Galena group, Southeastern Minnesota: Indicators of fluid flow and provenance of terrigenous material

    USGS Publications Warehouse

    Lively, R.S.; Morey, G.B.; Mossler, J.H.

    1997-01-01

    As part of a regional geochemical investigation of lower Paleozoic strata in the Hollandale embayment of southeastern Minnesota, elemental concentrations in acid-insoluble residues were determined for carbonate rock in the Middle Ordovician Galena Group. Elemental distribution patterns within the insoluble residues, particularly those of Ti, Al, and Zr, show that the Wisconsin dome and the Wisconsin arch, which contributed sediment to the embayment prior to Galena time, continued as weak sources of sediment during this period. In contrast, trace metals commonly associated with Mississippi Valley-type lead-zinc mineralization, including Pb, Zn, Cu, Ag, Ni, Co, As, and Mo, show dispersal patterns that are independent of those associated with primary depositional phenomena. These trace metals are concentrated in southern Minnesota in carbonate rocks near the interface between limestone- and dolostone-dominated strata. Dispersal patterns imply that the metals were carried by a north-flowing regional ground-water system. The results show that the geochemical attributes of insoluble residues can be used to distinguish provenance and transport directions of primary sediments within a depositional basin from effects of subsequent regional ground-water flow systems.

  13. Low keV electron probe analysis of silicate minerals for Mg, Al, and Si using pure-element standards

    NASA Technical Reports Server (NTRS)

    Cunningham, G. G.

    1972-01-01

    Accurate electron probe values for Mg, Al, and Si in silicate minerals may be obtained with pure-element standards. Analysis must be done at low (6 kV) accelerating potential and for best results, the average atomic number of the sample should be within about plus or minus 1 of the atomic number of the pure-element standard. This last requirement is automatically fulfilled for most common silicate minerals, as their average atomic numbers usually fall within the 11 to 15 range. Examples studied include a wet-chemically analyzed cordierite containing 17.71 weight percent Al, for which a value of 17.6 plus or minus 0.3 percent was obtained with the electron probe, and a hornblende containing 19.15 percent Si, which gave 19.0 plus or minus 0.3 percent using the probe method.

  14. Renormalization group and the Fermi surface in the Luttinger model. G. Benfatto 1 , G. Gallavotti 2 , V. Mastropietro 3

    E-print Network

    Renormalization group and the Fermi surface in the Luttinger model. G. Benfatto 1 , G. Gallavotti 2 is independent of L up to terms of order 1=L), and fi 0 is the velocity at the Fermi surface; â??v of view of the renormalization group. A perturbation theory of the beta function of the model is derived

  15. 75 FR 35786 - Resale Power Group of Iowa, WPPI Energy v. ITC Midwest LLC, Interstate Power and Light Company...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-23

    ...No. EL10-68-000] Resale Power Group of Iowa, WPPI Energy v. ITC Midwest LLC, Interstate Power and Light Company; Notice of Filing June 16, 2010...that, on June 15, 2010, Resale Power Group of Iowa and WPPI Energy filed a...

  16. An Instrument to Measure Elemental Energy Spectra of Cosmic Ray Nuclei Up to 10(exp 16) eV

    NASA Technical Reports Server (NTRS)

    Adams, J.; Bashindzhagyan, G.; Chilingarian, A.; Drury, L.; Egorov, N.; Golubkov,S.; Korotkova, N.; Panasyuk, M.; Podorozhnyi, D.; Procqureur, J.

    2000-01-01

    A longstanding goal of cosmic ray research is to measure the elemental energy spectra of cosmic rays up to and through the "knee" (approx. equal to 3 x 10 (exp 15) eV. It is not currently feasible to achieve this goal with an ionization calorimeter because the mass required to be deployed in Earth orbit is very large (at least 50 tonnes). An alternative method will be presented. This is based on measuring the primary particle energy by determining the angular distribution of secondaries produced in a target layer using silicon microstrip detector technology. The proposed technique can be used over a wide range of energies (10 (exp 11)- 10 (exp 16) eV) and gives an energy resolution of 60% or better. Based on this technique, a design for a new lightweight instrument with a large aperture (KLEM) will be described.

  17. Measurement of the Cabibbo-Kobayashi-Maskawa matrix element V(ub) with B-->rhoenu decays.

    PubMed

    Aubert, B; Barate, R; Boutigny, D; Gaillard, J-M; Hicheur, A; Karyotakis, Y; Lees, J P; Robbe, P; Tisserand, V; Zghiche, A; Palano, A; Pompili, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Gill, M S; Gritsan, A V; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kolomensky, Yu G; Kral, J F; LeClerc, C; Levi, M E; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Romosan, A; Ronan, M T; Shelkov, V G; Telnov, A V; Wenzel, W A; Harrison, T J; Hawkes, C M; Knowles, D J; O'Neale, S W; Penny, R C; Watson, A T; Watson, N K; Deppermann, T; Goetzen, K; Koch, H; Lewandowski, B; Pelizaeus, M; Peters, K; Schmuecker, H; Steinke, M; Barlow, N R; Bhimji, W; Boyd, J T; Chevalier, N; Clark, P J; Cottingham, W N; Mackay, C; Wilson, F F; Hearty, C; Mattison, T S; McKenna, J A; Thiessen, D; Jolly, S; Kyberd, P; McKemey, A K; Blinov, V E; Bukin, A D; Buzykaev, A R; Golubev, V B; Ivanchenko, V N; Korol, A A; Kravchenko, E A; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Yushkov, A N; Best, D; Chao, M; Kirkby, D; Lankford, A J; Mandelkern, M; McMahon, S; Mommsen, R K; Stoker, D P; Buchanan, C; Hadavand, H K; Hill, E J; MacFarlane, D B; Paar, H P; Rahatlou, Sh; Raven, G; Schwanke, U; Sharma, V; Berryhill, J W; Campagnari, C; Dahmes, B; Kuznetsova, N; Levy, S L; Long, O; Lu, A; Mazur, M A; Richman, J D; Verkerke, W; Beringer, J; Eisner, A M; Grothe, M; Heusch, C A; Lockman, W S; Pulliam, T; Schalk, T; Schmitz, R E; Schumm, B A; Seiden, A; Turri, M; Walkowiak, W; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Hitlin, D G; Narsky, I; Porter, F C; Ryd, A; Samuel, A; Yang, S; Jayatilleke, S; Mancinelli, G; Meadows, B T; Sokoloff, M D; Barillari, T; Blanc, F; Bloom, P; Ford, W T; Nauenberg, U; Olivas, A; Rankin, P; Roy, J; Smith, J G; van Hoek, W C; Zhang, L; Harton, J L; Hu, T; Soffer, A; Toki, W H; Wilson, R J; Zhang, J; Altenburg, D; Brandt, T; Brose, J; Colberg, T; Dickopp, M; Dubitzky, R S; Hauke, A; Lacker, H M; Maly, E; Müller-Pfefferkorn, R; Nogowski, R; Otto, S; Schubert, K R; Schwierz, R; Spaan, B; Wilden, L; Bernard, D; Bonneaud, G R; Brochard, F; Cohen-Tanugi, J; T'Jampens, S; Thiebaux, Ch; Vasileiadis, G; Verderi, M; Anjomshoaa, A; Bernet, R; Khan, A; Lavin, D; Muheim, F; Playfer, S; Swain, J E; Tinslay, J; Falbo, M; Borean, C; Bozzi, C; Piemontese, L; Sarti, A; Treadwell, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Falciai, D; Finocchiaro, G; Patteri, P; Peruzzi, I M; Piccolo, M; Zallo, A; Bagnasco, S; Buzzo, A; Contri, R; Crosetti, G; Lo Vetere, M; Macri, M; Monge, M R; Passaggio, S; Pastore, F C; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Bailey, S; Morii, M; Grenier, G J; Mallik, U; Cochran, J; Crawley, H B; Lamsa, J; Meyer, W T; Prell, S; Rosenberg, E I; Yi, J; Davier, M; Grosdidier, G; Höcker, A; Laplace, S; Le Diberder, F; Lepeltier, V; Lutz, A M; Petersen, T C; Plaszczynski, S; Schune, M H; Tantot, L; Wormser, G; Bionta, R M; Brigljevi?, V; Lange, D J; van Bibber, K; Wright, D M; Bevan, A J; Fry, J R; Gabathuler, E; Gamet, R; George, M; Kay, M; Payne, D J; Sloane, R J; Touramanis, C; Aspinwall, M L; Bowerman, D A; Dauncey, P D; Egede, U; Eschrich, I; Morton, G W; Nash, J A; Sanders, P; Taylor, G P; Back, J J; Bellodi, G; Dixon, P; Harrison, P F; Shorthouse, H W; Strother, P; Vidal, P B; Cowan, G; Flaecher, H U; George, S; Green, M G; Kurup, A; Marker, C E; McMahon, T R; Ricciardi, S; Salvatore, F; Vaitsas, G; Winter, M A; Brown, D; Davis, C L; Allison, J; Barlow, R J; Forti, A C; Hart, P A; Jackson, F; Lafferty, G D; Lyon, A J; Savvas, N; Weatherall, J H; Williams, J C; Farbin, A; Jawahery, A; Lillard, V; Roberts, D A; Blaylock, G; Dallapiccola, C; Flood, K T; Hertzbach, S S; Kofler, R; Koptchev, V B; Moore, T B; Staengle, H; Willocq, S; Cowan, R; Sciolla, G; Taylor, F; Yamamoto, R K; Milek, M; Patel, P M; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H; Hast, C; Taras, P; Nicholson, H; Cartaro, C; Cavallo, N; De Nardo, G; Fabozzi, F; Gatto, C; Lista, L; Paolucci, P; Piccolo, D; Sciacca, C; LoSecco, J M; Alsmiller, J R G; Gabriel, T A; Brau, B; Brau, J; Frey, R; Iwasaki, M; Potter, C T; Sinev, N B; Strom, D; Torrence, E; Colecchia, F; Dorigo, A; Galeazzi, F; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Tiozzo, G; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; de la Vaissière, Ch; Del Buono, L; Hamon, O; Leruste, Ph; Ocariz, J; Pivk, M; Roos, L; Stark, J; Manfredi, P F; Re, V; Speziali, V; Gladney, L; Guo, Q H; Panetta, J; Angelini, C; Batignani, G; Bettarini, S; Bondioli, M; Bucci, F; Calderini, G; Campagna, E; Carpinelli, M; Forti, F; Giorgi, M A; Lusiani, A

    2003-05-01

    We present a measurement of the branching fraction for the rare decays B-->rhoenu and extract a value for the magnitude of V(ub), one of the smallest elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are given for five different calculations of form factors used to para-metrize the hadronic current in semileptonic decays. Using a sample of 55 x 10(6) BB meson pairs recorded with the BABAR detector at the PEP-II e(+)e(-) storage ring, we obtain B(B0-->rho(-)e(+)nu)=(3.29+/-0.42+/-0.47+/-0.55) x 10(-4) and |V(ub)|=(3.64+/-0.22+/-0.25(+0.39)(-0.56)) x 10(-3), where the uncertainties are statistical, systematic, and theoretical, respectively. PMID:12785997

  18. Host isotope mass effects on the hyperfine interaction of group-V donors in silicon

    NASA Astrophysics Data System (ADS)

    Sekiguchi, T.; Tyryshkin, A. M.; Tojo, S.; Abe, E.; Mori, R.; Riemann, H.; Abrosimov, N. V.; Becker, P.; Pohl, H.-J.; Ager, J. W.; Haller, E. E.; Thewalt, M. L. W.; Morton, J. J. L.; Lyon, S. A.; Itoh, K. M.

    2014-09-01

    The effects of host isotope mass on the hyperfine interaction of group-V donors in silicon are revealed by pulsed electron nuclear double resonance (ENDOR) spectroscopy of isotopically engineered Si single crystals. Each of the hyperfine-split 31P, As75, Sb121, Sb123, and Bi209 ENDOR lines splits further into multiple components, whose relative intensities accurately match the statistical likelihood of the nine possible average Si masses in the four nearest-neighbor sites due to random occupation by the three stable isotopes Si28, Si29, and Si30. Further investigation with 31P donors shows that the resolved ENDOR components shift linearly with the bulk-averaged Si mass.

  19. Unveiling transient GaAs/GaP nanowire growth behavior using group V oscillations

    NASA Astrophysics Data System (ADS)

    Boulanger, J. P.; LaPierre, R. R.

    2014-02-01

    Patterned arrays of gold-assisted vapor-liquid-solid (VLS) nanowires (NWs) were grown on Si(111) substrates by gas source molecular beam epitaxy (MBE). GaAs/GaP heterostructures were grown with periodic modulation of the group V composition. Study of these oscillations by high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) enabled the measurement of the instantaneous growth rate throughout the NW. Novel transient growth behavior, NW dissolution, droplet purging, and droplet refilling were observed to occur at the GaAs/GaP hetero-interface. These behaviors were linked to the large change in chemical potential difference between the liquid droplet and the crystal solid when switching between As and P.

  20. TheoSSA - Model WD Spectra on Demand: The Impact of Ne, Na, Mg, and Iron-group Elements on the Balmer Lines

    NASA Astrophysics Data System (ADS)

    Reindl, N.; Rauch, T.

    2015-06-01

    The registered German Astrophysical Virtual Observatory (GAVO) service TheoSSA provides easy access to synthetic stellar spectra. This GAVO database contains already ten thousands of these, which were calculated with different chemical compositions of the elements H to Ni. In addition to the database, it is possible to calculate individual spectra for hot, compact stars based on the Tübingen NLTE Model-Atmosphere Package (TMAP) via the TMAW service. The TMAW models were, in the pilot phase, restricted to the elements H, He, C, N, and O. Now, TMAW is extended to additionally consider opacities from Ne, Na, and Mg. Soon, TMAW will also be able to include the opacities from the so-called iron-group elements (Ca - Ni). We describe the improvements and show the impact of Ne, Na, Mg, and iron-group elements on the Balmer lines.

  1. Elemental content from 0 to 500 keV neutrons: Lunar Prospector results

    Microsoft Academic Search

    I. Genetay; S. Maurice; W. C. Feldman; O. Gasnault; D. J. Lawrence; R. C. Elphic; C. d'Uston; A. B. Binder

    2003-01-01

    Neutron spectroscopy is a new way to study planetary bodies that have sufficiently thin atmospheres. This technique was demonstrated for the first time with Lunar Prospector around the Moon. Here, we report results for moderated neutrons having energies from 0 to 500keV that were measured using the anti-coincidence shield (ACS) of the gamma-ray spectrometer. We describe the detection method, followed

  2. Optimization of parameters for semiempirical methods V: Modification of NDDO approximations and application to 70 elements

    PubMed Central

    2007-01-01

    Several modifications that have been made to the NDDO core-core interaction term and to the method of parameter optimization are described. These changes have resulted in a more complete parameter optimization, called PM6, which has, in turn, allowed 70 elements to be parameterized. The average unsigned error (AUE) between calculated and reference heats of formation for 4,492 species was 8.0 kcal mol?1. For the subset of 1,373 compounds involving only the elements H, C, N, O, F, P, S, Cl, and Br, the PM6 AUE was 4.4 kcal mol?1. The equivalent AUE for other methods were: RM1: 5.0, B3LYP 6–31G*: 5.2, PM5: 5.7, PM3: 6.3, HF 6–31G*: 7.4, and AM1: 10.0 kcal mol?1. Several long-standing faults in AM1 and PM3 have been corrected and significant improvements have been made in the prediction of geometries. Figure Calculated structure of the complex ion [Ta6Cl12]2+ (footnote): Reference value in parenthesis Electronic supplementary material The online version of this article (doi:10.1007/s00894-007-0233-4) contains supplementary material, which is available to authorized users. PMID:17828561

  3. Effect of process parameters on deep drawing of Ti-6Al-4V alloy using finite element analysis

    NASA Astrophysics Data System (ADS)

    Kotkunde, Nitin; Deole, Aditya D.; Gupta, A. K.; Singh, S. K.

    2013-12-01

    Deep drawing process depends on the large number of process parameters and their interdependence. Optimization of process parameters in deep drawing is a vital task to reduce manufacturing cost and understand their influence on the deformation behaviour of the sheet metal. In this paper, significance of important process parameters namely, punch speed, blank holder pressure (BHP) and temperature on the deep-drawing characteristics of a Ti-6Al-4V alloy are investigated. Taguchi technique was employed to identify the influence of these parameters on thickness distribution. The finite element model of deep drawing process has been built up and analyzed using Dynaform version 5.6.1 with LS-Dyna version 971 as solver. Based on the predicted thickness distribution of the deep drawn circular cup and analysis of variance (ANOVA) results, it is concluded that punch speed has the greatest influence on the deep drawing of Ti-6Al-4V alloy blank sheet. Temperature and BHP effect are negligible in deep drawing of Ti-6Al-4V alloy at low warm temperatures (less than 450°C) but it may contribute to a significant extent at higher temperature. Also thickness distribution is predicted using artificial neural network (ANN). It is observed that the predicted thickness distribution is in good agreement with the experimental data.

  4. Effect of small additional elements on DBTT of V 4Cr 4Ti irradiated at low temperatures

    NASA Astrophysics Data System (ADS)

    Shibayama, Tamaki; Yamagata, Ichiro; Kayano, Hideo; Namba, Chusei

    1998-10-01

    As a part of a program to screen several V-4Cr-4Ti containing Si, Al and Y alloys and optimize the amounts of Si, Al and Y, the Charpy impact test of five kinds of V-4Cr-4Ti-Si-Al-Y alloys by an instrumented Charpy impact testing machine using miniaturized specimens (1.5 mm × 1.5 mm × 20 mm) have been conducted before and after neutron irradiation. Charpy impact specimens were encapsulated in an aluminum vial filled with high purity He and irradiated up to 1.06 × 10 19 n/cm 2 ( E > 1 MeV, 156 h) at low temperatures (about 150°C) in Japan Materials Testing Reactor (JMTR). The ductile brittle transition temperature (DBTT) of each alloy was determined by various methods on absorbed energy, brittle fracture ratio and lateral expansion from a quantitative analysis of fractography for broken specimens after the Charpy impact test. Almost all specimens were embrittled after low temperature irradiation. Decomposition of primary precipitates could result in migration of interstitial elements to irradiation defects and many precipitates are formed under irradiation. Radiation hardening then caused the substantial degradation of its fracture toughness.

  5. Platinum group elements provide no indication of a meteoritic component in ICDP cores from the Bosumtwi crater, Ghana

    NASA Astrophysics Data System (ADS)

    Goderis, S.; Tagle, R.; Schmitt, R. T.; Erzinger, J.; Claeys, P. H.

    In an attempt to identify the type of projectile, 14 samples from the Bosumtwi crater in Ghana were analyzed for platinum group element (PGE) concentrations by nickel sulfide fire assay inductively coupled plasma-mass spectrometry (ICP-MS). The majority of the samples come from the impactite material recovered by cores LB-07A and LB-08A, which were drilled by the International Continental Scientific Drilling program (ICDP). One sample originates from the fallback material found at the contact between the impactite and the overlying lake sediment in core LB-05B. No clear signature of a meteoritic contamination was identified in the 13 impactite samples. The target rock apparently dominates the PGE contribution in the impactites. These results agree with the PGE concentrations reported for the suevites collected at the crater rim and in other parts of the Bosumtwi ICDP cores. However, based on Cr and Os isotopic signatures, a meteoritic component could be present in the sample of fallback material, supporting the reports of the existence of meteoritic material in the Ivory Coast tektites. Further analyses of the fallback material from the Bosumtwi drill cores should confirm (or not) this first result.

  6. Fragmentation Cross Sections of 290 and 400 MeV/nucleon 12C Beamson Elemental Targets

    SciTech Connect

    Zeitlin, C.; Guetersloh, S.; Heilbronn, L.; Miller, J.; Fukumura,A.; Iwata, Y.; Murakami, T.

    2007-03-17

    Charge-changing and fragment production cross sections at 0circ have been obtained for interactions of 290 MeV/nucleon and 400MeV/nucleon carbon beams with C, CH2, Al, Cu, Sn, and Pb targets. Thesebeams are relevant to cancer therapy, space radiation, and the productionof radioactive beams. We compare to previously published results using Cand CH2 targets at similar beam energies. Due to ambiguities arising fromthe presence of multiple fragments on many events, previous publicationshave reported only cross sections for B and Be fragments. In this work wehave extracted cross sections for all fragment species, using dataobtained at three distinct values of angular acceptance, supplemented bydata taken with the detector stack placed off the beam axis. A simulationof the experiment with the PHITS Monte Carlo code shows fair agreementwith the data obtained with the large acceptance detectors, but agreementis poor at small acceptance. The measured cross sections are alsocompared to the predictions of the one-dimensional cross section modelsEPAX2 and NUCFRG2; the latter is presently used in NASA's space radiationtransport calculations. Though PHITS and NUCFRG2 reproduce thecharge-changing cross sections with reasonable accuracy, none of themodels is able to accurately predict the fragment cross sections for allfragment species and target materials.

  7. Subgroup Lattice If G is a group, then its subgroup lattice, L(G) = (V, E), is defined as follows

    E-print Network

    Subgroup Lattice If G is a group, then its subgroup lattice, L(G) = (V, E), is defined as follows: The vertex set V is composed of all distinct subgroups H in G. If |H| is a product of exactly i primes, then H is in level i of L(G), denoted H L(i)(G). Suppose H L(i)(G) and K L(j)(G) where j > i. Then {H

  8. Grass pollen immunotherapy induces highly cross-reactive IgG antibodies to group V allergen from different grass species.

    PubMed

    van Ree, R; Brewczy?ski, P Z; Tan, K Y; Mulder-Willems, H J; Widjaja, P; Stapel, S O; Aalberse, R C; Kroon, A M

    1995-03-01

    Sera from two groups of patients receiving grass pollen immunotherapy were tested on IgG reactivity with group V allergen from six different grass species. One group of patients was treated with a mixture of 10 grass species, and the other with a mixture of five. Only Lolium perenne, Dactylis glomerata, and Phleum pratense were present in both mixtures. Although Anthoxanthum odoratum and Secale cereale were absent from the mixture of five, IgG responses to Ant o V and Sec c V were comparable in both patient groups. This reactivity was inhibited for 92-99% with L. perenne extract, illustrating the cross-reactive nature of the IgG antibodies. The presence of A. odoratum and S. cereale in the mixture resulted in only minor amounts of species-specific anti-group V IgG. These results indicate that application of just one grass species in immunotherapy might be sufficient to induce an IgG response that covers other relevant Gramineae species as well. PMID:7677246

  9. Comparison of the analytical sensitivities for non-1/ v elements in different neutron beams

    NASA Astrophysics Data System (ADS)

    Révay, Zsolt

    2007-10-01

    Irregular nuclides such as 113Cd, and some rare-earth isotopes show different analytical sensitivities in PGAA performed at different facilities, because the cross-sections of these nuclides have strong low-energy resonances which partly overlap the energy range of typical neutron beams used for activation. A series of systematic measurements has been performed in the spectrally different cold and thermal neutron beams of the Budapest Research Reactor, Hungary and at the research reactor of NIST, Gaithersburg, USA to quantitatively study the non-1/v behaviour of irregular nuclides. Samples were prepared that contained one of the irregular nuclides and also a regular one (10B, 35Cl and 56Fe) and their activation ratios were compared as measured in five different beams. Theoretical values of the activation ratios were calculated from estimates of the actual neutron spectra and cross-section data, and show a generally good correspondence to the experimental results, although some details are still not reproduced.

  10. Platinum-group elements as petrological indicators in mafic-ultramafic complexes of the central and southern Urals: preliminary results

    NASA Astrophysics Data System (ADS)

    Garuti, G.; Fershtater, G.; Bea, F.; Montero, P.; Pushkarev, E. V.; Zaccarini, F.

    1997-07-01

    Platinum-group elements (PGE) and gold were analyzed by ICP-MS after the Ni-sulphide fire assay pre-concentration step in 44 rocks from 5 orogenic mafic-ultramafic massifs of the central and southern Urals. They comprise: (a) ring-zoned, Ural-Alaskan type bodies of the 'Pt-bearing belt' (Kachkanar, Tagil, Uktus); and (b) lherzolite-harzburgite complexes overlain by layered wehrlite, gabbro, and diorite (Nurali, Mindyak) supposed to be ophiolite-type suites. Total PGE and Au contents are generally higher in Ural-Alaskan type complexes compared with lherzolite-harzburgite complexes. Mantle-normalized PGE patterns range from nearly unfractionated in the dunites ( {Pd}/{Ir} = 0.57-3.68 ) to mildly and strongly fractionated in wehrlite, clinopyroxenite, and gabbro ( {Pd}/{Ir} = 9.1-187 ). Exceptionally high values of {Pd}/{Ir} (761-2622) are observed in amphibole-rich lithologies at Kachkanar, possibly indicating a relationship between fractionation of the less refractory Pd and increased fluid activity in the parental magma. Pronounced, positive Pt-anomalies, up to 20 times the mantle estimate, distinguishes the Ural-Alaskan type dunites, and progressively reduces in pyroxenites and gabbros. In the lherzolite-harzburgite complexes of Mindyak and Nurali, layered wehrlites and pyroxenites, as well as rocks from the gabbro-diorite units have fractionated PGE patterns ( {Pd}/{Ir} = 2.94-92.39 ) and positive Pt-anomaly as in the Ural-Alaskan complexes. Conversely, the Pt-anomaly is negative in the peridotites, and increases from lherzolites and harzburgites, to dunites, similarly to residual mantle from alpine-type orogenic massifs. The {Pd}/{Ir} (0.71-3.7) is higher than in ophiolites, and resembles that of lherzolite massifs of the western Mediterranean, representing sub-continental mantle. Variation of the Pt-anomaly versus {Pd}/{Ir} in Ural-Alaskan type complexes and in the layered sequences overlaying lherzolite-harzburgite mantle suites is consistent with magmatic fractionation, in which Pt behaves as a compatible element. It reflects a progressive depletion by partial melting in mantle peridotites, the Pt becoming incompatible in the last stage of melting in which Pt-poor residual dunites are formed. The positive Pt-anomaly in Ural-Alaskan type complexes is striking, and would appear as a distinctive feature of the parent magma, probably inherited from its mantle source.

  11. Finite element simulation of conventional and prestressed cutting of Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Peng, Ruitao; Tang, Xinzi; Tan, Yuanqiang; Liu, Xiongwei

    2013-05-01

    Titanium alloys are known as difficult-to-machine materials, chip morphology plays a predominant role in determining machinability and tool wear during the machining of titanium alloys. Based on the finite element analysis and experimental validation, the cutting processes in conventional cutting and prestressed cutting of titanium alloy ring parts were explored respectively. The Johnson-Cook model expressed by equivalent plastic strain flow stress is utilized to describe the constitutive properties. A ductile fracture criterion based on the strain energy is applied to model the crack initiation and evolution during the chip segmentation. Cutting force as well as distributions of stress, temperature and equivalent plastic strain along cutting time were numerically compared. The results indicate that in conventional cutting and prestressed cutting, chips show the similar characteristic of continuous and regular serrated shape. Initial stress distribution of workpiece was changed by prestress, which correspondingly leads to the alteration of stress distribution in the subsurface layer. Prestress hardly influences the distributions of temperature and equivalent plastic strain on workpiece. The cutting force curves share the same average amplitude and analogous undulating rhythm.

  12. Bactericidal Properties of Human and Murine Groups I, II, V, X, and XII Secreted Phospholipases A2

    Microsoft Academic Search

    Rao S. Koduri; Juha O. Gronroos; Veli J. O. Laine; Timo J. Nevalainen; Michael H. Gelb

    2002-01-01

    Group IIA secreted phospholipase A2 (sPLA2) is known to display potent Gram-positive bactericidal ac- tivity in vitro and in vivo. We have analyzed the bacte- ricidal activity of the full set of recombinant murine and human groups I, II, V, X, and XII sPLA2s on Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli. The rank order potency among human sPLA2s against

  13. Volatile Elements Production Rates in a 1.4-GeV Proton-Irradiated Molten Lead-Bismuth Target

    NASA Astrophysics Data System (ADS)

    Zanini, L.; Andersson, M.; Everaerts, P.; Fallot, M.; Frânberg, H.; Gröschel, F.; Jost, C.; Kirchner, T.; Kojima, Y.; Köster, U.; Lebenhaft, J.; Manfrin, E.; Pitcher, E.; Ravn, H.; Tall, Y.; Wagner, W.; Wohlmuther, M.

    2005-05-01

    Production rates of volatile elements following the spallation reaction of 1.4-GeV protons on a liquid Pb/Bi target have been measured. The experiment was performed at the ISOLDE facility at CERN. These data are of interest for the development of targets for accelerator-driven systems such as MEGAPIE. Additional data have been taken on a liquid Pb target. Calculations were performed using the FLUKA and MCNPX Monte Carlo codes coupled with the evolution codes ORIHET3 and FISPACT using different options for the intra-nuclear cascades and evaporation models. Preliminary results from the data analysis show good comparison with calculations for Hg and for noble gases. For other elements such as I, it is apparent that only a fraction of the produced isotopes is released. The agreement with the experimental data varies depending on the model combination used. The best results are obtained using MCNPX with the INCL4/ABLA models and with FLUKA. Discrepancies are found for some isotopes produced by fission using the MCNPX with the Bertini intranuclear cascade model coupled with the Dresner evaporation model.

  14. Petrology, geochemistry and the mechanisms determining the distribution of platinum-group element and base metal sulphide mineralisation in the Platreef at Overysel, northern Bushveld Complex, South Africa

    Microsoft Academic Search

    David A. Holwell; Iain McDonald

    2006-01-01

    Platinum-group element (PGE) mineralisation within the Platreef at Overysel is controlled by the presence of base metal sulphides (BMS). The floor rocks at Overysel are Archean basement gneisses, and unlike other localities along the strike of the Platreef where the floor is comprised of Transvaal Supergroup sediments, the intimate PGE–BMS relationship holds strong into the footwall rocks. Decoupling of PGE

  15. Sequence analysis of a group of low molecular-weight plasmids carrying multiple IS903 elements flanking a kanamycin resistance aph gene in Salmonella enterica serovars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A group of low molecular-weight ColE1-like plasmids carrying the aph sequence type aph(ii), from three different Salmonella serovars were sequenced. These plasmids carry 2 or more copies of IS903 elements, with up to 21 bp sequence differences to one another, two of which flank the aph gene. This g...

  16. Report of the IAU\\/IAG\\/COSPAR Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites: 1994

    Microsoft Academic Search

    M. E. Davies; V. K. Abalakin; M. Bursa; J. H. Lieske; B. Morando; D. Morrison; P. K. Seidelmann; A. T. Sinclair; B. Yallop; Y. S. Tjuflin

    1995-01-01

    Every three years the IAU\\/IAG\\/COSPAR Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Stallites revises tables giving the directions of the north poles of rotation and the prime meridians of the planets, satellites, and asteroids. Also presented are revised tables giving their sizes and shapes.

  17. Broadening And Shift of The Intercombination Spectral Line of The Second Group Elements (Hg, Cd and Zn) Perturbed by Inert Gases

    Microsoft Academic Search

    G. D. Roston; Z. F. Ghatass; M. S. Helmi

    2002-01-01

    The Van der Waals and Lennard - Jones potential parameters for the ground and exited states of the second group elements (Hg, Cd and Zn) perturbed by inert gases (Xe, Kr, Ar, Ne and He) have been calculated using coulomb approximation. The basis of the Lindholm -Foley impact theory and the calculated potential parameters are used for calculating the collision

  18. Alteration and the role of fluids in Ni, Cu and platinum-group element deposition, Sudbury Igneous Complex contact, Onaping-Levack area, Ontario

    Microsoft Academic Search

    Catharine E. G. Farrow; D. H. Watkinson

    1992-01-01

    Summary A variety of alteration styles is associated with Cu, Ni and platinum-group element deposition in the Onaping-Levack area of the North Range of the Sudbury Structure. Two significant alteration assemblages are amphibole (actinolite) + epidote + chlorite + quartz ± albite ± K-feldspar ± calcite adjacent to Cu-rich veins in the Deep Copper Zone of Strathcona mine and the

  19. Re-Os systematics in chondrites and the fractionation of the platinum group elements in the early solar system

    NASA Astrophysics Data System (ADS)

    Chen, J. H.; Papanastassiou, D. A.; Wasserburg, G. J.

    1998-10-01

    We have investigated the Re-Os system for samples of whole rock, metal, and sulfide from ordinary chondrites. Using closed-system analytical techniques, we found complete exchange between sample and tracer isotopes for silicate-containing samples and obtained precise and reliable Re-Os concentration measurements. Results on two Group IVA iron meteorites and on a silicate-rich iron (Steinbach, IVA-AN) are consistent with the IVA-IVB isochron and support the previous observation that IVA-IVB irons may be slightly older than IIAB irons. Data on whole-rock fragments and metal-rich separates from the St. Séverin chondrite (LL6) show a large range in 187Re/ 188Os and in 187Os/ 188Os, which makes possible, in principle, the determination of a Re-Os internal isochron on a chondrite, for the first time. This Re-Os fractionation may be due to partial melting of FeNiS and macroscopic redistribution of metal and sulfide. The St. Séverin data show a good correlation line on a 187Re- 187Os evolution diagram. If this is considered to represent an internal isochron, it gives an age T = 4.68 ± 0.15 AE [?( 187Re) = 1.64 × 10 -11 a -1] and an initial ( 187Os/ 188Os) 0 = 0.0953 ± 0.0013. This age is in agreement with but slightly older than the more precise 187Re- 187Os age for the IIAB irons as well as for irons from other groups (T = 4.61 ± 0.01 AE). A St. Séverin sulfide nodule has very low Re and Os concentrations and shows a young Re-Os model age (2.3 AE), indicating recent element remobilization. Whole rock and metal-rich separates of H-Group chondrites (H3 to H6) yield restricted ranges in 187Re/ 188Os (0.42-0.47) and 187Os/ 188Os (0.128-0.133). There is a systematic difference between Re/Os in the metal extracted from a chondrite and the bulk chondrite. This shows that there is a small but significant Re-Os fractionation within subsystems contained in the chondrites. From whole rock samples of H Group chondrites we calculate a mean 187Re/ 188Os = 0.423 ± 0.007 and 187Os/ 188Os = 0.12863 ± 0.00046, which may characterize the evolution of an average chondritic reservoir for Re-Os. The ordinary chondrite data plot close to the IIAB isochron, although the deviations found are larger than found for the irons. The Re-Os chronometer in iron meteorites is apparently controlled by the Re-Os fractionation due to fractional crystallization of liquid metal. Re-Os ages of iron meteorites give the time of crystallization of metal segregations and cores of early planetary bodies. In contrast, the behavior in ordinary chondrites, while also dominated by the metal phases, must reflect fractionation and transport on a local macroscopic scale within the chondrites between the metal phases after aggregation, due to partial melting of FeNiS or represent variable Re-Os fractionation of the metal phases prior to the accretion of the chondrites. However, for St. Séverin, we attribute the major Re-Os fractionation to early heating of the meteorite, above the Fe-FeS eutectic. We do not consider that the Re-Os fractionation observed in other chondrites is due to the redistribution of Re and Os during chondrite metamorphism (including shock) but it may plausibly represent earlier stages of Re-Os fractionation for the different FeNi metal constituents prior to accretion.

  20. VEGF stimulation of endothelial cell PAF synthesis is mediated by group V 14 kDa secretory phospholipase A2

    E-print Network

    Dennis, Edward A.

    VEGF stimulation of endothelial cell PAF synthesis is mediated by group V 14 kDa secretory Jolla, California, CA, 92093-0601, U.S.A. 1 Vascular endothelial growth factor (VEGF) is a potent assessed their contribution to VEGF-induced PAF synthesis in bovine aortic EC (BAEC) and human umbilical

  1. Platinum Group Elements (PGE) geochemistry of komatiites and boninites from Dharwar Craton, India: Implications for mantle melting processes

    NASA Astrophysics Data System (ADS)

    Saha, Abhishek; Manikyamba, C.; Santosh, M.; Ganguly, Sohini; Khelen, Arubam C.; Subramanyam, K. S. V.

    2015-06-01

    High MgO volcanic rocks having elevated concentrations of Ni and Cr are potential hosts for platinum group elements (PGE) owing to their primitive mantle origin and eruption at high temperatures. Though their higher PGE abundance is economically significant in mineral exploration studies, their lower concentrations are also valuable geochemical tools to evaluate petrogenetic processes. In this paper an attempt has been made to evaluate the PGE geochemistry of high MgO volcanic rocks from two greenstone belts of western and eastern Dharwar Craton and to discuss different mantle processes operative at diverse geodynamic settings during the Neoarchean time. The Bababudan greenstone belt of western and Gadwal greenstone belt of eastern Dharwar Cratons are dominantly composed of high MgO volcanic rocks which, based on distinct geochemical characteristics, have been identified as komatiites and boninites respectively. The Bababudan komatiites are essentially composed of olivine and clinopyroxene with rare plagioclase tending towards komatiitic basalts. The Gadwal boninites contain clinopyroxene, recrystallized hornblende with minor orthopyroxene, plagioclase and sulphide minerals. The Bababudan komatiites are Al-undepleted type (Al2O3/TiO2 = 23-59) with distinctly high MgO (27.4-35.8 wt.%), Ni (509-1066 ppm) and Cr (136-3036 ppm) contents. These rocks have low ?PGE (9-42 ppb) contents with 0.2-2.4 ppb Iridium (Ir), 0.2-1.4 ppb Osmium (Os) and 0.4-4.4 ppb Ruthenium (Ru) among Iridium group PGE (IPGE); and 1.4-16.2 ppb Platinum (Pt), 2.8-19 ppb Palladium (Pd) and 0.2-9.8 ppb Rhodium (Rh) among Platinum group PGE (PPGE). The Gadwal boninites are high-Ca boninites with CaO/Al2O3 ratios varying between 0.8 and 1.0, with 12-24 wt.% MgO, 821-1168 ppm Ni and 2307-2765 ppm Cr. They show higher concentration of total PGE (82-207 ppb) with Pt concentration ranging from 13 to 19 ppb, Pd between 65 and 180 ppb and Rh in the range of 1.4-3 ppb compared to the Bababudan komatiites. Ir, Os and Ru concentrations range from 0.6 to 2.2 ppb, 0.2 to 0.6 ppb and 1.4 to 2.6 ppb respectively in IPGE. The PGE abundances in Bababudan komatiites were controlled by olivine fractionation whereas that in Gadwal boninites were influenced by fractionation of chromite and sulphides. The Al-undepleted Bababudan komatiites are characterized by low CaO/Al2O3, (Gd/Yb)N, (La/Yb)N, with positive Zr, Hf, Ti anomalies and high Cu/Pd, Pd/Ir ratios at low Pd concentrations suggesting the derivation of parent magma by high degrees (>30%) partial melting of mantle under anhydrous conditions at shallow depth with garnet as a residual phase in the mantle restite. The komatiites are geochemically analogous to Al-undepleted Munro type komatiites and their PGE compositions are consistent with Alexo and Gorgona komatiites. The S-undersaturated character of Bababudan komatiites is attributed to decompression and assimilation of lower crustal materials during magma ascent and emplacement. In contrast, the higher Al2O3/TiO2, lower (Gd/Yb)N, for Gadwal boninites in combination with negative Nb, Zr, Hf, Ti anomalies and lower Cu/Pd at relatively higher Pd/Ir and Pd concentrations reflect high degree melting of refractory mantle wedge under hydrous conditions in an intraoceanic subduction zone setting. Higher Pd/Ir ratios and S-undersaturation of these boninites conform to influx of fluids derived by dehydration of subducted slab resulting into high fluid pressure and metasomatism of mantle wedge.

  2. Theoretical predictions of properties and volatility of chlorides and oxychlorides of group-4 elements. I. Electronic structures and properties of MCl4 and MOCl2 (M = Ti, Zr, Hf, and Rf)

    NASA Astrophysics Data System (ADS)

    Pershina, V.; Borschevsky, A.; Iliaš, M.

    2014-08-01

    Relativistic, infinite order exact two-component, density functional theory electronic structure calculations were performed for MCl4 and MOCl2 of group-4 elements Ti, Zr, Hf, and element 104, Rf, with the aim to predict their behaviour in gas-phase chromatography experiments. RfCl4 and RfOCl2 were shown to be less stable than their lighter homologs in the group, tetrachlorides and oxychlorides of Zr and Hf, respectively. The oxychlorides turned out to be stable as a bent structure, though the stabilization energy with respect to the flat one (C2v) is very small. The trend in the formation of the tetrachlorides from the oxychlorides in group 4 is shown to be Zr < Hf < Rf, while the one in the formation of the oxychlorides from the chlorides is opposite. All the calculated properties are used to estimate adsorption energy of these species on various surfaces in order to interpret results of gas-phase chromatography experiments, as is shown in Paper II.

  3. Theoretical predictions of properties and volatility of chlorides and oxychlorides of group-4 elements. I. Electronic structures and properties of MCl? and MOCl? (M = Ti, Zr, Hf, and Rf).

    PubMed

    Pershina, V; Borschevsky, A; Iliaš, M

    2014-08-14

    Relativistic, infinite order exact two-component, density functional theory electronic structure calculations were performed for MCl4 and MOCl2 of group-4 elements Ti, Zr, Hf, and element 104, Rf, with the aim to predict their behaviour in gas-phase chromatography experiments. RfCl4 and RfOCl2 were shown to be less stable than their lighter homologs in the group, tetrachlorides and oxychlorides of Zr and Hf, respectively. The oxychlorides turned out to be stable as a bent structure, though the stabilization energy with respect to the flat one (C(2v)) is very small. The trend in the formation of the tetrachlorides from the oxychlorides in group 4 is shown to be Zr < Hf < Rf, while the one in the formation of the oxychlorides from the chlorides is opposite. All the calculated properties are used to estimate adsorption energy of these species on various surfaces in order to interpret results of gas-phase chromatography experiments, as is shown in Paper II. PMID:25134578

  4. Groups and topology in the Euler hydrodynamics and KdV

    E-print Network

    Khesin, Boris A.

    (t,x) = v(t,g(t,x)), g(0,x) = x. Acceleration of particles is given by 2 t g(t,x) = (tv the right translation). This way we obtain the evolution law for v(t), given by a (non-linear) dynamical (t,x) g(t,x) describing the motion of fluid particles is defined by its velocity field v(t,x): tg

  5. SEPARATION AND PURIFICATION OF RARE EARTH ELEMENTS BY FRACTIONAL CRYSTALLIZATION. IV. PURIFICATIONS OF CERIUM GROUP ELEMENTS BY FRACTIONAL CRYSTALLIZATIONS OF DOUBLE SALTS OF NITRATES

    Microsoft Academic Search

    Shiokawa

    1963-01-01

    By fractional crystallizations of double salts of nitrates, binary ; mixtures of cerium-group elemen were purified. The samples of binary mixtures ; used in these experiments were ohtained by the fractional crystallization of ; double magnesium nitrate. In the purification of La and Pr from La- Pr mixture, ; the fractional crystallization of double ammonium nitrate was carried out using

  6. arXiv:math.DG/0406011v11Jun2004 The exceptional holonomy groups

    E-print Network

    Joyce, Dominic

    at the 11th G¨okova Geometry and Topology Conference in May 2004, sponsored by TUBITAK. In keeping, perhaps the most mysterious are the two exceptional cases, the holonomy group G2 in 7 dimensions and the holonomy group Spin(7) in 8 dimensions. This is a survey paper on the exceptional holonomy groups, in two

  7. Platinum-group element abundance and distribution in chromite deposits of the Acoje Block, Zambales Ophiolite Complex, Philippines

    USGS Publications Warehouse

    Bacuta, G.C., Jr.; Kay, R.W.; Gibbs, A.K.; Lipin, B.R.

    1990-01-01

    Platinum-group elements (PGE) occur in ore-grade concentration in some of the chromite deposits related to the ultramafic section of the Acoje Block of the Zambales Ophiolite Complex. The deposits are of three types: Type 1 - associated with cumulate peridotites at the base of the crust; Type 2 - in dunite pods from the top 1 km of mantle harzburgite; and Type 3 - like Type 2, but in deeper levels of the harzburgite. Most of the deposites have chromite compositions that are high in Cr with Cr/(Cr + Al) (expressed as chromium index, Cr#) > 0.6; high-Al (Cr# Pd, thought to be characteristic of PGE-barren deposits) and positive slope (Ir < Pd, characteristic of PGE-rich deposits). Iridium, Ru and Os commonly occur as micron-size laurite (sulfide) inclusions in unfractured chromite. Laurite and native Os are also found as inclusions in interstitial sulfides. Platinum and Pd occur as alloy inclusions (and possibly as solid solution) in interstitial Ni-Cu sulfides and as tellurobismuthides in serpentine and altered sulfides. Variability of PGE distribution may be explained by alteration, crystal fractionation or partial melting processes. Alteration and metamorphism were ruled out, because PGE contents do not correlate with degree of serpentinization or the abundance and type (hydroxyl versus non-hydroxyl) of silicate inclusions in chromite. Preliminary Os isotopic data do not support crustal contamination as a source of the PGEs in the Acoje deposits. The anomalous PGE concentrations in Type 1 high-Cr chromite deposits are attributed to two stages of enrichment: an early enrichment of their mantle source from previous melting events and a later stage of sulfide segregation accompanying chromite crystallization. High-Al chromite deposits which crystallized from basalts derived from relatively low degrees of melting owe their low PGE content to partitioning of PGEs in sulfides and alloys that remain in the mantle. High-Cr deposits crystallized from melts that were previously enriched with PGEs during early melting events of their mantle source; Pt and Pd ore concentrations (ppm levels) are attained by segregation of magmatic sulfides. The Acoje deposits indicate that ophiolites are a potential economic source of the PGEs. ?? 1990.

  8. Elements’ important ranking of China drug safety management system: applying the non-structural fuzzy group decision method

    Microsoft Academic Search

    Xiaoping Zheng; Xiaocui Wang; Tingkuan Zhong

    2010-01-01

    Drug safety management is an important issue in China drug management system and attracts great attentions from the whole\\u000a society. In order to reduce drug incident, this study discusses some important elements associated with China drug safety\\u000a management system and analyzes the data collected by questionnaires. Besides, a methodology for rating the important elements\\u000a is described and applied. The non-structural

  9. 'Weird' crystal structures of elements at high pressure

    Microsoft Academic Search

    Tat'yana N Kolobyanina

    2002-01-01

    New crystal structures, in particular incommensurate composite crystals, discovered in the high-pressure phases of Group I, II, IV, and V elements are described, and their intermetallic and other binary structural analogs are discussed.

  10. A tool to design steel elements submitted to compartment fires—OZone V2. Part 1: pre- and post-flashover compartment fire model

    Microsoft Academic Search

    J. F. Cadorin; J. M. Franssen

    2003-01-01

    The computer code OZone V2 has been developed to help engineers in designing structural elements submitted to compartment fires. The code is based on several recent developments, in compartment fire modelling on one hand and on the effect of localised fires on structures on the other hand. It includes a single compartment fire model that combines a two-zone model and

  11. arXiv:math.GT/0306069v13Jun2003 AUTOMORPHISMS OF SURFACE BRAID GROUPS

    E-print Network

    McCarthy, John D.

    group of the quotient of S[n] by this action of n ([I3]). Likewise, the pure n-string braid group PBn(S) and PBn(S). The natural isomorphism from PBn(S) to PModR(S) arises from the con- necting homomorphism), ...., f(xn)), where (x1, ..., xn) is the chosen base point for the fundamental group PBn(S) of S

  12. Platinum-group elements in southern Africa: mineral inventory and an assessment of undiscovered mineral resources: Chapter Q in Global Mineral Resource Assessment

    USGS Publications Warehouse

    Zientek, Michael L.; Causey, J. Douglas; Parks, Heather L.; Miller, Robert J.

    2014-01-01

    The platinum-group elements, platinum, palladium, rhodium, ruthenium, iridium, and osmium, possess unique physical and chemical characteristics that make them indispensable to modern technology and industry. However, mineral deposits that are the main sources of these elements occur only in three countries in the world, raising concerns about potential disruption in mineral supply. Using information in the public domain, mineral resource and reserve information has been compiled for mafic and ultramafic rocks in South Africa and Zimbabwe that host most of the world’s platinum-group element resources. As of 2012, exploration and mining companies have delineated more than 20 billion metric tons of mineralized rock containing 42,000 metric tons of platinum, 29,000 metric tons of palladium, and 5,200 metric tons of rhodium, primarily in mafic and ultramafic intrusions of the Bushveld Complex and the Great Dyke, in southern Africa. Additional mineralized rock is likely to occur in extensions to the well-explored and characterized volumes of mineralized rock. Underexplored extensions of stratabound platinum-group element (PGE) deposits in the Bushveld Complex in South Africa may contain 65,000 metric tons of platinum, palladium, and rhodium to a depth of 3 km. Rocks enriched in PGE, which occur near the contact of the Bushveld Complex with older Transvaal Supergroup sedimentary rocks, may contain 1,100 metric tons of platinum and 1,370 metric tons of palladium (mean estimate to a depth of 1 km). A stratabound platinum-group element deposit in the Great Dyke in Zimbabwe may contain 6,900 metric tons of undiscovered platinum, palladium, and rhodium. By comparison, the global net demand for PGE in 2012 was approximately 460 metric tons. Since the 1920s, mining has recovered 7,200 and 107 metric tons of platinum-group elements from the Bushveld Complex and the Great Dyke, respectively. The large layered intrusions in southern Africa—the Bushveld Complex and the Great Dyke—are now and will continue to be a major source of the world’s supply of PGE. Mining will not deplete the identified mineral resources and reserves or potential undiscovered mineral resources for many decades; however, in the near-term, PGE supply could be affected by social, environmental, political, and economic factors.

  13. Study of the reaction. pi. ⁻ + ¹²C. -->. pi. ⁻ + ¹²C* (4. 44 MeV) at 4. 5 GeV\\/c. [Angular distribution, electric quadrupole transition, polarization, density matrix elements, cross sections

    Microsoft Academic Search

    J. L. Groves; L. E. Holloway; L. J. Jr. Koester; W. Liu; L. J. Nodulman; D. G. Ravenhall; R. L. Schult; J. H. Smith

    1977-01-01

    Characteristic 4.44-MeV ..gamma.. rays from the first excited state of carbon were observed in coincidence with scattered 4.5-GeV\\/c ..pi..⁻ mesons in counters and wire spark chambers. The ..gamma..-ray angular distribution in the momentum-transfer frame confirms the electric quadrupole nature of the transition and reveals the polarization of the recoiling ¹²C* nucleus so that density matrix elements can be determined. A

  14. The coupling of thermochemistry and phase diagrams for group III-V semiconductor systems. Final report

    SciTech Connect

    Anderson, T.J.

    1998-07-21

    The project was directed at linking the thermochemical properties of III-V compound semiconductors systems with the reported phase diagrams. The solid-liquid phase equilibrium problem was formulated and three approaches to calculating the reduced standard state chemical potential were identified and values were calculated. In addition, thermochemical values for critical properties were measured using solid state electrochemical techniques. These values, along with the standard state chemical potentials and other available thermochemical and phase diagram data, were combined with a critical assessment of selected III-V systems. This work was culminated with a comprehensive assessment of all the III-V binary systems. A novel aspect of the experimental part of this project was the demonstration of the use of a liquid encapsulate to measure component activities by a solid state emf technique in liquid III-V systems that exhibit high vapor pressures at the measurement temperature.

  15. I. ASCRC General Education Form Group V Literary and Artistic Studies

    E-print Network

    Vonessen, Nikolaus

    , semiotics, gender theory, psychoanalysis, etc). #12;V. Student Learning Goals: Briefly explain how to psychoanalysis and deconstruction. Particular emphasis is placed on reading the text in a historical and cultural

  16. Survey of the Distribution and Time-Dependent Increase of Platinum-Group Element Accumulation Along Urban Roads in Ioannina (NW Greece)

    Microsoft Academic Search

    George Z. Tsogas; Dimosthenis L. Giokas; Athanasios G. Vlessidis; Maria Aloupi; Michael O. Angelidis

    2009-01-01

    The emission of platinum group elements (PGEs) from automobile catalytic converters has led to rapid increases in Pt, Pd,\\u000a and Rh concentrations in roadside media. This article represents the first systematic study in Greece to assess PGE levels\\u000a in road dust and roadside soil and their temporal variation on a seasonal basis over a 12-month period. Road dust and roadside

  17. Group I elements in ZnO B.K. Meyer, N. Volbers, A. Zeuner, S. Lautenschlger, J. Sann, A.Hoffmann1

    E-print Network

    Nabben, Reinhard

    Group I elements in ZnO B.K. Meyer, N. Volbers, A. Zeuner, S. Lautenschläger, J. Sann, A.Hoffmann1. 36, D-10623 Berlin, Germany ABSTRACT In this report we focus on the lithium doping of ZnO epitaxial films grown on GaN templates and ZnO substrates. We compare the results with diffusion studies of Li

  18. The sporadic occurrence of a group I intron-like element in the mtDNA rnl gene of Ophiostoma novo-ulmi subsp. americana.

    PubMed

    Sethuraman, Jyothi; Okoli, Chukwuemeka V; Majer, Anna; Corkery, Tamara L C; Hausner, Georg

    2008-05-01

    The presence of group I intron-like elements within the U7 region of the mtDNA large ribosomal subunit RNA gene (rnl) was investigated in strains of Ophiostoma novo-ulmi subsp. americana from Canada, Europe and Eurasia, and in selected strains of O. ips, O. minus, O. piceae, O. ulmi, and O. himal-ulmi. This insertion is of interest as it has been linked previously to the generation of plasmid-like mtDNA elements in diseased strains of O. novo-ulmi. Among 197 O. novo-ulmi subsp. americana strains tested, 61 contained a 1.6kb insertion within the rnl-U7 region and DNA sequence analysis suggests the presence of a group I intron (IA1 type) that encodes a potential double motif LAGLIDADG homing endonuclease-like gene (HEG). Phylogenetic analysis of rnl-U7 intron encoded HEG-like elements supports the view that double motif HEGs originated from a duplication event of a single-motif HEG followed by a fusion event that combined the two copies into one open reading frame (ORF). The data also show that rnl-U7 intron encoded ORFs belong to a clade that includes ORFs inserted into different types of group I introns, e.g. IB, ID, IC3, IA1, present within a variety of different mtDNA genes, such as the small ribosomal subunit RNA gene (rns), apo-cytochrome b gene (cob), NADH dehydrogenase subunit 5 (nad5), cytochrome oxidase subunit 1 gene (coxI), and ATPase subunit 9 gene (atp9). We also compared the occurrence of the rnl-U7 intron in our collection of 227 strains with the presence of the rnl-U11 group I intron and concluded that the U7 intron appears to be an optional element and the U11 intron is probably essential among the strains tested. PMID:18406119

  19. Comparison of synthetic fluid inclusion and quartz-trap methods for determining platinum- group element (PGE) solubility in hydrous salt melts at magmatic conditions

    Microsoft Academic Search

    J. J. Hanley

    2007-01-01

    Layered intrusions preserve magmatic inclusions containing hydrous halide melt phases composed of transition metal chlorides with less than 5 wt% H2O. Previous attempts at measuring platinum-group element (PGE) solubility in such high salinity volatiles through the analysis of synthetic fluid inclusions have shown that, although the PGE appear to be highly soluble at geologically-realistic conditions, it is difficult to determine

  20. Increase of platinum group element concentrations in soils and airborne dust in an urban area in Germany.

    PubMed

    Wichmann, Hubertus; Anquandah, George A K; Schmidt, Christiane; Zachmann, Dieter; Bahadir, Muefit A

    2007-12-15

    Since 1993, all new cars sold in the European Union had to be fitted with catalytic converters. Undoubtedly, these measures brought about a great progress concerning traffic emission controls. However, this technology also led to new emissions. A rapid accumulation of the catalytic active noble metals Pt, Pd, and Rh in the environment was observed and concern arose about potential environmental and health risks. This work aimed at a contribution to a monitoring of platinum group element (PGE) emission and accumulation by comparing analytical data, all generated in 1999 and in 2005 in an urban area in Germany. Oriented at the 1999 sampling strategy, soil and airborne dust samples were taken in 2005 at the same sampling sites located mainly close to heavily used roads in the region of Braunschweig. For the enrichment of the analytes, conditioned soil samples as well as loaded glass fiber filters from air sampling were transferred to the nickel sulphide fire assay. For analyses, the ICP-MS technique was applied. High Pt, Pd, and Rh concentrations were detected especially in top soil layers (0-2 cm) directly at the roadsides or on center strips. At one road outside the city, where traffic moved with a constant speed of about 80 km/h, maximum concentrations in soil were found to be 50.4 microg/kg for Pt, 43.3 microg/kg for Pd, and 10.7 microg/kg for Rh. PGE concentrations were the highest close to that road and exponentially declined with growing distance. At a second road, where vehicles run with a constant speed of 50 km/h, the highest concentrations were detected in the center strip soil: 88.9 microg/kg (Pt), 77.8 microg/kg (Pd), and 17.6 microg/kg (Rh). At a third crowded street in the centre of Braunschweig with stop and go traffic, the highest soil concentrations were determined, namely 261 microg/kg for Pt, 124 microg/kg for Pd and 38.9 microg/kg for Rh. The sampling of airborne dust at this roadside revealed for Pt 159 pg/m(3) air or 1730 microg/kg dust, for Pd 37.8 pg/m(3) air or 410 microg/kg dust, and for Rh 10.0 pg/m(3) air or 110 microg/kg dust. A comparison of analytical results of 2005 with those of 1999 revealed a distinct increase of PGE concentrations in soils closely along heavy traffic roads by a factor of 2.1 to 8.9; once even a factor of 15 was determined. The findings also document, that especially Pt and Rh concentrations were elevated in airborne dust. PMID:17884143

  1. Report of the MIT Global Environment Initiative Planning Group John H. Lienhard V

    E-print Network

    Reif, Rafael

    development personnel, ILP leadership and alumni. As part of the process, the Planning Group should pursue a synergistic relationship with MITEI. The Planning Group should also lay that could be presented to the new leadership of MIT. This would ideally be concise

  2. Revised ab initio natural band offsets of all group IV, II-VI, and III-V semiconductors

    Microsoft Academic Search

    Yong-Hua Li; Aron Walsh; Shiyou Chen; Wan-Jian Yin; Ji-Hui Yang; Jingbo Li; Juarez L. F. da Silva; X. G. Gong; Su-Huai Wei

    2009-01-01

    Using an all-electron band structure approach, we have systematically calculated the natural band offsets between all group IV, III-V, and II-VI semiconductor compounds, taking into account the deformation potential of the core states. This revised approach removes assumptions regarding the reference level volume deformation and offers a more reliable prediction of the ``natural'' unstrained offsets. Comparison is made to experimental

  3. Les Houches Physics at TeV Colliders 2005 Beyond the Standard Model Working Group: Summary Report

    SciTech Connect

    Allanach, B.C.; /Cambridge U., DAMTP; Grojean, C.; /Saclay, SPhT /CERN; Skands, P.; /Fermilab; Accomando, E.; Azuelos, G.; Baer, H.; Balazs, C.; Belanger, G.; Benakli, K.; Boudjema, F.; Brelier, B.; Bunichev, V.; Cacciapaglia, G.; Carena, M.; Choudhury, D.; Delsart, P.-A.; De Sanctis, U.; Desch, K.; Dobrescu, B.A.; Dudko, L.; El Kacimi, M.; /Saclay,

    2006-03-17

    The work contained herein constitutes a report of the ''Beyond the Standard Model'' working group for the Workshop ''Physics at TeV Colliders'', Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well as computational tools designed in order to facilitate their phenomenology.

  4. Revised ab initio natural band offsets of all group IV, II-VI, and III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Li, Yong-Hua; Walsh, Aron; Chen, Shiyou; Yin, Wan-Jian; Yang, Ji-Hui; Li, Jingbo; Da Silva, Juarez L. F.; Gong, X. G.; Wei, Su-Huai

    2009-05-01

    Using an all-electron band structure approach, we have systematically calculated the natural band offsets between all group IV, III-V, and II-VI semiconductor compounds, taking into account the deformation potential of the core states. This revised approach removes assumptions regarding the reference level volume deformation and offers a more reliable prediction of the "natural" unstrained offsets. Comparison is made to experimental work, where a noticeable improvement is found compared to previous methodologies.

  5. Nucleolar introns from Physarum flavicomum contain insertion elements that may explain how mobile group I introns gained their open reading frames.

    PubMed Central

    Vader, A; Naess, J; Haugli, K; Haugli, F; Johansen, S

    1994-01-01

    Comparison of two group I intron sequences in the nucleolar genome of the myxomycete Physarum flavicomum to their homologs in the closely related Physarum polycephalum revealed insertion-like elements. One of the insertion-like elements consists of two repetitive sequence motifs of 11 and 101 bp in five and three copies, respectively. The smaller motif, which flanks the larger, resembles a target duplication and indicates a relationship to transposons or retroelements. The insertion-like elements are found in the peripheral loops of the RNA structure; the positions occupied by the ORFs of mobile nucleolar group I introns. The P. flavicomum introns are 1184 and 637 bp in size, located in the large subunit ribosomal RNA gene, and can be folded into group I intron structures at the RNA level. However, the intron 2s from both P. flavicomum and P. polycephalum contain an unusual core region that lacks the P8 segment. None of the introns are able to self-splice in vitro. Southern analysis of different isolates indicates that the introns are not optional in myxomycetes. Images PMID:7984404

  6. Spin-orbit effects, VSEPR theory, and the electronic structures of heavy and superheavy group IVA hydrides and group VIIIA tetrafluorides. A partial role reversal for elements 114 and 118

    SciTech Connect

    Nash, C.S. [Lawrence Livermore National Lab., CA (United States). Glenn T. Seaborg Inst. for Transactinium Science] [Lawrence Livermore National Lab., CA (United States). Glenn T. Seaborg Inst. for Transactinium Science; Bursten, B.E. [Ohio State Univ., Columbus, OH (United States). Dept. of Chemistry] [Ohio State Univ., Columbus, OH (United States). Dept. of Chemistry

    1999-01-21

    Relativistic effective core potentials and spin-orbit operators are used in relativistic configuration interaction calculations to explore the effects of spin-orbit coupling on the electronic structures of atoms and molecules of elements 114 and 118. The monohydrides of group IVA and the tetrafluorides of group VIIIA are examined in order to provide examples of trends within families among the various periods. The spin-orbit effect is found to play a dominant role in the determination of atomic and molecular properties. Several nonintuitive consequences of spin-orbit coupling are presented, including the depiction of element 114 as a closed-shell noble atom and the suggestion that the VSEPR theory in inadequate to describe the geometry of the rare gas tetrafluoride, (118)F{sub 4}.

  7. Photoionization of As2 and As4: Implications for group V clusters

    NASA Astrophysics Data System (ADS)

    Yoo, R. K.; Ruscic, B.; Berkowitz, J.

    1992-05-01

    The vacuum ultraviolet photoionization mass spectrum of As4 is presented, from the ionization threshold to 600 Å. The apparent adiabatic ionization potential is ?8.49 eV, but the true value may be significantly lower. Three broad autoionization features are observed, probably comprising members of a Rydberg series converging to the B˜ 2A1 state of As+4. The first fragment, As+3, has an appearance potential (0 K) of 11.23±0.05 eV, from which we extract ?H0f0(As+3)?228.7±1.3 kcal/mol. The photoion yield curve of As+2(As2) is obtained under conditions where As2 is dominant in the vapor. The adiabatic ionization potential is 9.69±0.02 eV. Two prominent autoionizing Rydberg series are observed, converging to the A 2?+g state of As+2, with an ionization potential of 10.238±0.002 eV. At higher energy, three members of a window resonance series can be seen, converging to the B 2?+u state of As+2, with an ionization potential of 15.37 eV. From an upper limit to the partial pressure of As3, equilibrium conditions, and assuming a triangular As3, we deduce ?H0f0(As3)?60.0 kcal/mol; other criteria suggest ?H0f0(As3)?63 kcal/mol. Consequently, the adiabatic ionization potential of As3 is <7.32 eV, and probably ?7.19 eV. Several implications are drawn, relevant to recent studies of antimony and bismuth clusters.

  8. The renaissance of homoatomic nine-atom polyhedra of the heavier carbon-group elements Si–Pb

    Microsoft Academic Search

    Thomas F Fässler

    2001-01-01

    Homoatomic nine-atom clusters of the elements Si, Ge, Sn, and Pb represent a fascinating class of molecules. The Zintl anions [E9]x? occur with different charges x and various shapes. Mixed valent compounds and polymeric chains via cluster linkage promise outstanding physical and chemical properties. A summary of recent progress in synthesis, crystal structure, EXAFS investigations, chemical bonding, Raman spectroscopy, mass

  9. The use of cation exchange matrix separation coupled with ICP-MS to directly determine platinum group element (PGE) and other trace element emissions from passenger cars equipped with diesel particulate filters (DPF).

    PubMed

    Cairns, Warren R L; De Boni, Antonella; Cozzi, Giulio; Asti, Massimo; Borla, Edoardo Merlone; Parussa, Flavio; Moretto, Ezio; Cescon, Paolo; Boutron, Claude; Gabrieli, Jacopo; Barbante, Carlo

    2011-03-01

    Inductively coupled plasma-mass spectrometry coupled with cation exchange matrix separation has been optimised for the direct determination of platinum group element (PGE) and trace element emissions from a diesel engine car. After matrix separation method detection limits of 1.6 ng g(-1) for Pd, 0.4 ng g(-1) for Rh and 4.3 ng g(-1) for Pt were achieved, the method was validated against the certified reference material BCR 723, urban road dust. The test vehicle was fitted with new and aged catalytic converters with and without diesel particulate filters (DPF). Samples were collected after three consecutive New European Driving Cycle (NEDC) of the particulate and "soluble" phases using a home-made sampler optimised for trace element analysis. Emission factors for the PGEs ranged from 0.021 ng km(-1) for Rh to 70.5 ng km(-1) for Pt; when a DPF was fitted, the emission factors for the PGEs actually used in the catalysts dropped by up to 97% (for Pt). Trace element emission factors were found to drop by a maximum of 92% for Ni to a minimum of 18% for Y when a DPF was fitted; a new DPF was also found to cause a reduction of up to 86% in the emission of particulate matter. PMID:21210274

  10. Deactivation of group III acceptors in silicon during keV electron irradiation

    SciTech Connect

    Sah, C.; Sun, J.Y.; Tzou, J.J.; Pan, S.C.

    1983-11-15

    Experimental results on p-Si metal-oxide-semiconductor capacitors (MOSC's) are presented which demonstrate the electrical deactivation of the acceptor dopant impurity during 8-keV electron irradiation not only in boron but also aluminum and indium-doped silicon. The deactivation rates of the acceptors during the 8-keV electron irradiation are nearly independent of the acceptor impurity type. The final density of the remaining active acceptor approaches nonzero values N/sub infinity/, with N/sub infinity/(B)Al--H>In-H. These deactivation results are consistent with our hydrogen bond model. The thermal annealing or regeneration rate of the deactivated acceptors in the MOSC's irradiated by 8-keV electron is much smaller than that in the MOSC's that have undergone avalanche electron injection, indicating that the keV electron irradiation gives rise to stronger hydrogen-acceptor bond.

  11. Chemical elements in the aragonitic and calcitic microstructural groups of shell of the oyster Crassostrea virginica : A proton probe study

    Microsoft Academic Search

    M. R. Carriker; C. P. Swann; R. S. Prezant; C. L. Counts

    1991-01-01

    We report the results of a study with proton-induced X-ray emissions (PIXE) of the distribution and concentration of 15 chemical elements (Na to Sr in periodic chart) in four microstructural and two mineralogical regions of shell of rapidly growing adult oysters [Crassostrea virginica (Gmelin)]. Hatchery-raised oysters were grown in Broadkill Estuary, Delaware, USA, for 16 wk in summer 1978. Their

  12. Photoionization of As2 and As4: Implications for group V clusters

    Microsoft Academic Search

    R. K. Yoo; B. Ruscic; J. Berkowitz

    1992-01-01

    The vacuum ultraviolet photoionization mass spectrum of As4 is presented, from the ionization threshold to 600 A?. The apparent adiabatic ionization potential is ?8.49 eV, but the true value may be significantly lower. Three broad autoionization features are observed, probably comprising members of a Rydberg series converging to the B˜ 2A1 state of As+4. The first fragment, As+3, has an

  13. X:\\Capital Development Group\\Documents & Forms & Guidelines\\Policies Procedures and Guidelines\\REF-FM-025 Space Management Guidelines V4

    E-print Network

    Li, Jiuyong "John"

    X:\\Capital Development Group\\Documents & Forms & Guidelines\\Policies Procedures and Guidelines Group member. #12;X:\\Capital Development Group\\Documents & Forms & Guidelines\\Policies Procedures\\REF-FM-025 Space Management Guidelines V4 260308.doc Page 1 of 7 REF-FM-025 REFERENCE DOCUMENT: Space

  14. Comparison of four grass pollen species concerning their allergens of grass group V by 2D immunoblotting and microsequencing.

    PubMed

    Petersen, A; Schramm, G; Becker, W M; Schlaak, M

    1993-09-01

    The identification and characterization of allergenic components is a vital step towards improving diagnosis and therapy. Members of the grass family (Poaceae) reveal a high cross-reactivity among each other caused by the close phylogenetical relationship. In order to investigate the variability between allergenic components, we studied the allergen grass group V, one of the major allergens. Pollen extracts of 4 different tribes (timothy grass (Phleum pratense)--Agrostidae, perennial rye grass (Lolium perenne)--Festuceae, meadow velvet (Holcus lanatus)--Aveneae, and rye (Secale cereale)--Triticeae) of the Festucoideae subfamily were separated by 2D PAGE and investigated by immunoblotting using patients' poolserum and monoclonal antibodies (raised against group V allergens of timothy grass pollen). The antibodies identify different allergens in the four grass species. The components vary from 30-50 kDa and pI 4.8-7.0. The eight NH2-terminal amino acids were determined and indicated high similarities between the different components. These results cast doubt on the suitability of classifying allergens into groups based only on their molecular mass, isoelectric point and N-terminal sequence analysis. It suggests to classify allergens according to their IgE-reactive epitopes. PMID:7505588

  15. Synthesis, structures and bonding of superconducting barium vanadium sulfide and intermetallic solid state compounds of group 2, 3, 13, 14 and transition elements

    Microsoft Academic Search

    Kim Carl Lobring

    2001-01-01

    Superconducting transition is well known for the Chevrel phases M xMo6S8 and MxMo6Se 8 where M is dopant metal such as Pb, In, Tl and La. Not many ternary group 5 transition metal chalcogenides of similar composition, however, are known to be superconductors. The synthesis and observation of superconducting transition of the Ba doped compound BaxV6S8 (x = 0.45--0.48) is

  16. Spin density matrix elements in exclusive electroproduction on H and H targets at 27.5 GeV beam energy

    NASA Astrophysics Data System (ADS)

    Airapetian, A.; Akopov, N.; Akopov, Z.; Augustyniak, W.; Avetissian, A.; Blok, H. P.; Borissov, A.; Bryzgalov, V.; Capiluppi, M.; Capitani, G. P.; Cisbani, E.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; De Leo, R.; De Sanctis, E.; Diefenthaler, M.; Di Nezza, P.; Düren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Etzelmüller, E.; Fabbri, R.; Felawka, L.; Frullani, S.; Gabbert, D.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Gavrilov, G.; Gharibyan, V.; Hartig, M.; Hasch, D.; Holler, Y.; Hristova, I.; Ivanilov, A.; Jackson, H. E.; Joosten, S.; Kaiser, R.; Karyan, G.; Keri, T.; Kinney, E.; Kisselev, A.; Korotkov, V.; Kozlov, V.; Kravchenko, P.; Krivokhijine, V. G.; Lagamba, L.; Lapikás, L.; Lehmann, I.; Lenisa, P.; Lorenzon, W.; Ma, B.-Q.; Mahon, D.; Manaenkov, S. I.; Mao, Y.; Marianski, B.; Marukyan, H.; Movsisyan, A.; Murray, M.; Naryshkin, Y.; Nass, A.; Nowak, W.-D.; Pappalardo, L. L.; Perez-Benito, R.; Petrosyan, A.; Reimer, P. E.; Reolon, A. R.; Riedl, C.; Rith, K.; Rostomyan, A.; Ryckbosch, D.; Schäfer, A.; Schnell, G.; Schüler, K. P.; Seitz, B.; Shibata, T.-A.; Stahl, M.; Stancari, M.; Statera, M.; Steffens, E.; Steijger, J. J. M.; Taroian, S.; Terkulov, A.; Truty, R.; Trzcinski, A.; Tytgat, M.; Van Haarlem, Y.; Van Hulse, C.; Vikhrov, V.; Vilardi, I.; Wang, S.; Yaschenko, S.; Yen, S.; Zeiler, D.; Zihlmann, B.; Zupranski, P.

    2014-11-01

    Exclusive electroproduction of mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of GeV, 3.0 GeV 6.3 GeV, and GeV. Results on the angular distribution of the meson, including its decay products, are presented. The data were accumulated with the HERMES forward spectrometer during the 1996-2007 running period using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio reveals that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are presented in projections of or . Violation of -channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse production by longitudinal and transverse virtual photons, and , is determined for the first time. A hierarchy of helicity amplitudes is established, which mainly means that the unnatural-parity-exchange amplitude describing the transition dominates over the two natural-parity-exchange amplitudes describing the and transitions, with the latter two being of similar magnitude. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions, which are of unnatural parity.

  17. Chemical Elements.com

    NSDL National Science Digital Library

    Yinon Bentor

    2007-12-12

    This is an online interactive periodic table of the elements which includes all elements up to 118. There are several different options for viewing, such as date of discovery, electron configuration, number of neutrons, etc. Elements can also be viewed by element groups. Additional links to further information on a particluar element are given in some cases. Citation information is also provided.

  18. Isoperimetric and Isodiametric Functions of Groups Mark V. Sapir, JeanCamille Birget, Eliyahu Rips \\Lambda

    E-print Network

    Sapir, Mark

    an isoperimetric function of a finite presentation P = hX j Ri of a group G if for every number n and every word w over X which is equal to 1 in G, jwj Ÿ n, there exists a van Kampen diagram over P whose boundary label = hX j Ri if for every number n and every word w over X which is equal to 1 in G, jwj Ÿ n

  19. Neutron activation cross sections at 14.4 MeV For some naturally occurring heavy elements in the region 76 <= Z <= 82

    Microsoft Academic Search

    A. K. Hankla; R. W. Fink; J. H. Hamilton

    1972-01-01

    Neutron activation cross sections at 14.4 MeV were determined for isotopes of the following naturally occurring heavy elements: Os, Pt, Au, Hg, Tl and Pb. The mixed-powder method with Ge(Li) gamma-detection was used, and the cross sections in mb are as follows. For (n, 2n) reactions (m = metastable; g = ground state); 192Os, 1993+\\/-200 (m+g); 192Pt, 2035+\\/-150 198Pt, 1009+\\/-100

  20. Finite-element analysis of residual stresses in Al 2O 3–TiC\\/W18Cr4V diffusion bonded joints

    Microsoft Academic Search

    Xiaoqin Shen; Yajiang Li; U. A. Putchkov; Juan Wang; Wanqun Huang

    2009-01-01

    The residual stress distribution in Al2O3–TiC\\/W18Cr4V diffusion bonded joints was calculated using finite element method (FEM). The effects of pressure and interlayer on the axial stress and shear stress were also studied. The results show that the gradients of the axial stress and shear stress are great near the joint edge and are flat near the center of the joint.

  1. Direct observation of N-(group V) bonding defects in dilute nitride semiconductors using hard x-ray photoelectron spectroscopy

    SciTech Connect

    Ishikawa, F.; Fuyuno, S.; Higashi, K.; Kondow, M. [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Machida, M.; Oji, H.; Son, J.-Y. [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5143 (Japan); Trampert, A. [Paul-Drude-Institute fuer Festkoeperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Umeno, K.; Furukawa, Y.; Wakahara, A. [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 441-8580 (Japan)

    2011-03-21

    Using bulk sensitive hard x-ray photoelectron spectroscopy, we directly observe a spectrum related to N-As bonding defects in (Ga,In)(N,As)/Ga(N,As) heterostructure. The defects are most likely attributed to split interstitials. Their concentration is in the order of 10{sup 19} cm{sup -3}, close to the detection limit of the measurement. Rapid thermal annealing eliminates the defects, leading to those undetectable. Similar phenomenon is observed for N-P bonding defects in In(N,P). The results indicate common features in dilute nitride semiconductor system: existence of N-(group V) bonding defects and their behavior on postgrowth annealing.

  2. Calculated Spin-Orbit Splittings of Some Group IV, III-V, and II-VI Semiconductors

    Microsoft Academic Search

    G. G. Wepfer; T. C. Collins; R. N. Euwema

    1971-01-01

    The spin-orbit splittings of the valence and conduction bands of the group-IV semiconductors Si, Ge, and alpha-Sn, the III-V compounds AlSb, GaP, GaAs, GaSb, InP, InAs, and InSb, and the II-VI compounds ZnS, ZnSe, ZnTe, and CdTe have been obtained at the Gamma, X, and L symmetry points in the Brillouin zone. The calculations were made using a relativistic orthogonalized

  3. A measurement of the top quark mass in 1.96 TeV proton-antiproton collisions using a novel matrix element method

    SciTech Connect

    Freeman, John C.; /LBL, Berkeley

    2007-12-01

    A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncertainty of the jet momentum reconstruction. As with all matrix elements techniques, the method involves an integration using the Standard Model matrix element for tt production and decay. however, the technique presented is unique in that the matrix element is modified to compensate for kinematic assumptions which are made to reduce computation time. Background events are dealt with through use of an event observable which distinguishes signal from background, as well as through a cut on the value of an event's maximum likelihood. Results are based on a 955 pb{sup -1} data sample, using events with a high-p{sub T} lepton and exactly four high-energy jets, at least one of which is tagged as coming from a b quark; 149 events pass all the selection requirements. They find M{sub meas} = 169.8 {+-} 2.3(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.

  4. Characterization of Group V Dubnium Homologs on DGA Extraction Chromatography Resin from Nitric and Hydrofluoric Acid Matrices

    SciTech Connect

    Despotopulos, J D; Sudowe, R

    2012-02-21

    Studies of the chemical properties of superheavy elements (SHE) pose interesting challenges due to their short half-lives and low production rates. Chemical systems must have extremely fast kinetics, fast enough kinetics to be able to examine the chemical properties of interest before the SHE decays to another nuclide. To achieve chemistry on such time scales, the chemical system must also be easily automated. Most importantly however, a chemical system must be developed which provides suitable separation and kinetics before an on-line study of a SHE can be performed. Relativistic effects make studying the chemical properties of SHEs interesting due to the impact these effects could have on the SHEs chemical properties. Relativistic effects arise when the velocity of the s orbital electrons approach the speed of light. As this velocity increases, the Bohr radius of the inner electron orbitals decreases and there is an increase in the particles mass. This contraction results in a destabilization of the energy of the outer d and f electron orbitals (5f and 6d in the case of SHE), which can cause these to expand due to their increased shielding from the nuclear charge. Another relativistic effect is the spin-orbit splitting for p, d, and f orbitals into j = 1 {+-} 1/2 states. This can lead most interestingly to a possible increased stability of element 114, which due to large spin-orbit splitting of the 7p orbital and the relativistically stabilized 7p{sub 1/2} and 7s orbital gives rise to a closed shell ground state of 7s{sup 2}7p{sub 1/2}{sup 2}. The homologs of element 105, dubnium (Db), Ta and Nb and the pseudo-homolog Pa, are well known to hydrolyze and form both neutral and non-neutral monoatomic and polyatomic species that may cause issues with extraction from a given chemical system. Early ion-exchange and solvent-extraction studies show mixed results for the behavior of Db. Some studies show Db behaving most similar to Ta, while others show it behaving somewhere between Nb and Pa. Much more recent studies have examined the properties of Db from HNO{sub 3}/HF matrices, and suggest Db forms complexes similar to those of Pa. Very little experimental work into the behavior of element 114 has been performed. Thermochromatography experiments of three atoms of element 114 indicate that the element 114 is at least as volatile as Hg, At, and element 112. Lead was shown to deposit on gold at temperatures about 1000 C higher than the atoms of element 114. Results indicate a substantially increased stability of element 114. No liquid phase studies of element 114 or its homologs (Pb, Sn, Ge) or pseudo-homologs (Hg, Cd) have been performed. Theoretical predictions indicate that element 114 is should have a much more stable +2 oxidation state and neutral state than Pb, which would result in element 114 being less reactive and less metallic than Pb. The relativistic effects on the 7p{sub 1/2} electrons are predicted to cause a diagonal relationship to be introduced into the periodic table. Therefore, 114{sup 2+} is expected to behave as if it were somewhere between Hg{sup 2+}, Cd{sup 2+}, and Pb{sup 2+}. In this work two commercially available extraction chromatography resins are evaluated, one for the separation of Db homologs and pseudo?homologs from each other as well as from potential interfering elements such as Group IV Rf homologs and actinides, and the other for separation of element 114 homologs. One resin, Eichrom's DGA resin, contains a N,N,N',N'-tetra-n-octyldiglycolamide extractant, which separates analytes based on both size and charge characteristics of the solvated metal species, coated on an inert support. The DGA resin was examined for Db chemical systems, and shows a high degree of selectivity for tri-, tetra-, and hexavalent metal ions in multiple acid matrices with fast kinetics. The other resin, Eichrom's Pb resin, contains a di-t-butylcyclohexano 18-crown-6 extractant with isodecanol solvent, which separates analytes based on steric interactions between the cavity of the crown ether and electrostatic interac

  5. Re-Os systematics in chondrites and the fractionation of the platinum group elements in the early solar system

    Microsoft Academic Search

    J. H Chen; D. A Papanastassiou; G. J Wasserburg

    1998-01-01

    We have investigated the Re-Os system for samples of whole rock, metal, and sulfide from ordinary chondrites. Using closed-system analytical techniques, we found complete exchange between sample and tracer isotopes for silicate-containing samples and obtained precise and reliable Re-Os concentration measurements. Results on two Group IVA iron meteorites and on a silicate-rich iron (Steinbach, IVA-AN) are consistent with the IVA-IVB

  6. H I Studies of the Sculptor Group Galaxies. V - NGC 253

    NASA Astrophysics Data System (ADS)

    Puche, D.; Carignan, C.; van Gorkom, J. H.

    1995-07-01

    A VLA HI map was made of NGC 253. In this study, there is a continuum map (ngc0253.con), an HI data cube (ngc0253.cub), and moment maps (ngc0253.m0 = total HI, ngc0253.m1 = velocity field, and ngc0253.m2 = second moment). These maps have been used in an extensive dynamical and kinematical study of the Sculptor Group galaxies. The images and related TeX file come from the NRAO CDROM "Images From the Radio Universe" (c. 1992 National Radio Astronomy Observatory, used with permission).

  7. Fossil group origins V. The dependence of the luminosity function on the magnitude gap

    E-print Network

    Zarattini, S; Sanchez-Janssen, R; Barrena, R; Boschin, W; del Burgo, C; Castro-Rodriguez, N; Corsini, E M; D'Onghia, E; Girardi, M; Iglesias-Paramo, J; Kundert, A; Mendez-Abreu, J; Vilchez, J M

    2015-01-01

    In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system ($\\Delta m_{12}$). There are systems with gaps close to zero (e.g., the Coma cluster), and at the other extreme of the distribution, the largest gaps are found among the so-called fossil systems. Fossil and non-fossil systems could have different galaxy populations that should be reflected in their luminosity functions. In this work we study, for the first time, the dependence of the luminosity function parameters on $\\Delta m_{12}$ using data obtained by the fossil group origins (FOGO) project. We constructed a hybrid luminosity function for 102 groups and clusters at $z \\le 0.25$. We stacked all the individual luminosity functions, dividing them into bins of $\\Delta m_{12}$, and studied their best-fit Schechter parameters. We additionally computed a relative luminosity function, expressed as a function of the central galaxy luminosity, which boosts our capacity to detect differ...

  8. The origin and distribution of HAPs elements in relation to maceral composition of the A1 lignite bed (Paleocene, Calvert Bluff Formation, Wilcox Group), Calvert mine area, east-central Texas

    USGS Publications Warehouse

    Crowley, S.S.; Warwick, P.D.; Ruppert, L.F.; Pontolillo, J.

    1997-01-01

    The origin and distribution of twelve potentially Hazardous Air Pollutants (HAPs; As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb Sb, Se, and U) identified in the 1990 Clean Air Act Amendments were examined in relation to the maceral composition of the A1 bed (Paleocene, Calvert Bluff Formation, Wilcox Group) of the Calvert mine in east-central Texas. The 3.2 m-thick A1 bed was divided into nine incremental channel samples (7 lignite samples and 2 shaley coal samples) on the basis of megascopic characteristics. Results indicate that As, Cd, Cr, Ni, Pb, Sb, and U are strongly correlated with ash yield and are enriched in the shaley coal samples. We infer that these elements are associated with inorganic constituents in the coal bed and may be derived from a penecontemporaneous stream channel located several kilometers southeast of the mining block. Of the HAPs elements studied, Mn and Hg are the most poorly correlated to ash yield. We infer an organic association for Mn; Hg may be associated with pyrite. The rest of the trace elements (Be, Co, and Se) are weakly correlated with ash yield. Further analytical work is necessary to determine the mode of occurrence for these elements. Overall, concentrations of the HAPs elements are generally similar to or less than those reported in previous studies of lignites of the Wilcox Group, east-central region, Texas. Petrographic analysis indicates the following ranges in composition for the seven lignite samples: liptinites (5-8%), huminites (88-95%), and inertinites (trace amounts to 7%). Samples from the middle portion of the A1 bed contain abundant crypto-eugelinite compared to the rest of the samples; this relationship suggests that the degradation of plant material was an important process during the development of the peat mire. With the exception of Hg and Mn, relatively low levels of the HAPs elements studied are found in the samples containing abundant crypto-eugelinite. We infer that the peat-forming environment for this portion of the coal bed was very wet with minimal detrital input. Relatively high concentrations of crypto-humotelinite were found in samples from the top and base of the coal bed. The presence of abundant crypto-humotelinite in this part of the coal bed suggests the accumulation of wood-rich peat under conditions conducive to a high degree of tissue preservation in the peat mire. Although several of the trace elements (Be, Co, Ni, and Sb) exhibit enrichment in these samples, they are not necessarily chemically associated with humotelinite. We infer that these elements, with the exception of Be, are possibly associated with deposition of the roof and floor rock of the coal bed; however, further analytical work would be necessary to confirm this hypothesis. Beryllium may have an organic origin. ?? 1997 Elsevier Science B.V.

  9. Repression of transcription mediated at a thyroid hormone response element by the v-erb-A oncogene product

    Microsoft Academic Search

    Jan Sap; Alberto Muñoz; Jackie Schmitt; Henk Stunnenberg; Björn Vennström

    1989-01-01

    SEVERAL recent observations1,2, such as the identification of the cellular homologue of the v-erb-A oncogene as a thyroid-hormone receptor3,4, have strongly implicated nuclear oncogenes in transcriptional control mechanisms. The v-erb-A oncogene blocks the differentiation of erythroid cells, and changes the growth requirements of fibroblasts and erythroblasts5-7. Mutations in v-erb-A protein have led to the loss of its affinity for thyroid

  10. Triple excitations in perturbed relativistic coupled-cluster theory and electric dipole polarizability of group-IIB elements

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, S.; Mani, B. K.; Angom, D.

    2015-05-01

    We use the perturbed relativistic coupled-cluster (PRCC) theory to compute the electric dipole polarizabilities ? of Zn, Cd, and Hg. The computations are done using the Dirac-Coulomb-Breit Hamiltonian with the Uehling potential to incorporate vacuum polarization corrections. To assimilate the self-energy corrections we use the model self-energy operator of Shabaev et al. [Phys. Rev. A 88, 012513 (2013), 10.1103/PhysRevA.88.012513]. The triple excitations are included perturbatively in the PRCC theory and nonperturbatively in the unperturbed sector. Our results for ? for all three elements are in excellent agreement with the experimental data. The other highlight of the results is the orbital energy corrections from Breit interactions. In the literature we could only get the data of Hg [E. Lindroth et al., J. Phys. B 22, 2447 (1989), 10.1088/0953-4075/22/16/004], which are a near perfect match with our results. We also present the linearized equations of the cluster amplitudes, including the triple excitations, with the angular factors.

  11. Rare earth, major, and trace elements in chert from the Franciscan complex and Monterey group, California: Assessing REE sources to fine-grained marine sediments

    SciTech Connect

    Murray, R.W.; Jones, D.L. (Univ. of California, Berkeley (United States)); Buchholtz Ten Brink, M.R.; Gerlach, D.C.; Russ, G.P. III (Lawrence Livermore National Lab., CA (United States))

    1991-07-01

    Rare earth element (REE), major, and trace element analyses of 77 samples from the Mesozoic Franciscan Complex and Miocene Monterey Group of California (USA) indicate that magnitudes of the Ce anomaly (Ce/Ce{asterisk}) and total REE abundances ({Sigma}REE) in these rocks are controlled dominantly by (a) amount of included metalliferous material, (b) the amount of direct terrigenous input, and (c) the overall burial rate. The relative importance of these individual processes varies across an ocean basin in such a way that REE relative fractionations and {Sigma}REE correspond with its depositional environment. The authors conclusions are supported by an extensive review of published REE data from various river, coastal, open-ocean, and ridge-influenced waters, as well as terrigenous, pelagic, and metalliferous sediment. The chert sequences record deposition in spreading ridge, open-ocean basin, and continental margin environments. The relative importance of metalliferous and terrigenous influences and the role of scavenging from seawater may be estimated from a sample's inferred depositional distance (km) from the spreading ridge, the major element chemistry, and the stratigraphic context. REEs in chert appear less affected by post-depositional processes than either major or trace elements, indicating that REEs are better tools for paleoceanographic or tectonic reconstructions that are based on chert chemistry. This work complements recent efforts to elucidate the factors determining large-scale REE distributions in marine sediments and has direct bearing on previous attempts to use the Ce anomaly in older rocks and sediments as a recorder of secular variations and anoxic events in the overlying water column.

  12. The UV/optical spectra of the Type Ia supernova SN 2010jn: a bright supernova with outer layers rich in iron-group elements

    NASA Astrophysics Data System (ADS)

    Hachinger, S.; Mazzali, P. A.; Sullivan, M.; Ellis, R. S.; Maguire, K.; Gal-Yam, A.; Howell, D. A.; Nugent, P. E.; Baron, E.; Cooke, J.; Arcavi, I.; Bersier, D.; Dilday, B.; James, P. A.; Kasliwal, M. M.; Kulkarni, S. R.; Ofek, E. O.; Laher, R. R.; Parrent, J.; Surace, J.; Yaron, O.; Walker, E. S.

    2013-03-01

    Radiative transfer studies of Type Ia supernovae (SNe Ia) hold the promise of constraining both the density profile of the SN ejecta and its stratification by element abundance which, in turn, may discriminate between different explosion mechanisms and progenitor classes. Here we analyse the Type Ia SN 2010jn (PTF10ygu) in detail, presenting and evaluating near-ultraviolet (near-UV) spectra from the Hubble Space Telescope and ground-based optical spectra and light curves. SN 2010jn was discovered by the Palomar Transient Factory (PTF) 15 d before maximum light, allowing us to secure a time series of four near-UV spectra at epochs from -10.5 to +4.8 d relative to B-band maximum. The photospheric near-UV spectra are excellent diagnostics of the iron-group abundances in the outer layers of the ejecta, particularly those at very early times. Using the method of `Abundance Tomography' we derive iron-group abundances in SN 2010jn with a precision better than in any previously studied SN Ia. Optimum fits to the data can be obtained if burned material is present even at high velocities, including significant mass fractions of iron-group elements. This is consistent with the slow decline rate (or high `stretch') of the light curve of SN 2010jn, and consistent with the results of delayed-detonation models. Early-phase UV spectra and detailed time-dependent series of further SNe Ia offer a promising probe of the nature of the SN Ia mechanism.

  13. Key elements of the human bocavirus type 1 (HBoV1) promoter and its trans-activation by NS1 protein

    PubMed Central

    2013-01-01

    Background Human bocavirus (HBoV), a parvovirus, is suspected to be an etiologic agent of respiratory disease and gastrointestinal disease in humans. All mRNAs of HBoV1 are transcribed from a single promoter. Methods In this study, we constructed EGFP and luciferase reporter gene vectors under the control of the HBoV1 full promoter (nt 1–252) and its mutated variants, respectively. Fluorescence microscopy was used to observe expression activities of the EGFP. Dual-luciferase reporter vectors were employed in order to evaluate critical promoter elements and the effect of NS1 protein on promoter activity. Results The HBoV1 promoter activity was about 2.2-fold and 1.9-fold higher than that of the CMV promoter in 293 T and HeLa cells, respectively. The putative transcription factor binding region of the promoter was identified to be located between nt 96 and nt 145. Mutations introduced in the CAAT box of the HBoV1 promoter reduced promoter activity by 34%, whereas nucleotide substitutions in the TATA box had no effect on promoter activity. The HBoV1 promoter activities in 293 T and HeLa cells, in the presence of NS1 protein, were 2- to 2.5-fold higher than those in the absence of NS1 protein. Conclusion The HBoV1 promoter was highly active in 293 T and HeLa cell lines, and the sequence from nt 96 to nt 145 was critical for the activity of HBoV1 promoter. The CAAT box, in contrast to the TATA-box, was important for optimum promoter activity. In addition, the transcriptional activity of this promoter could be trans-activated by the viral nonstructural protein NS1 in these cells. PMID:24161033

  14. Simultaneous removal of elemental mercury and NO from flue gas by V2O5-CeO2/TiO2 catalysts

    NASA Astrophysics Data System (ADS)

    Zhang, Xunan; Li, Caiting; Zhao, Lingkui; Zhang, Jie; Zeng, Guangming; Xie, Yin'e.; Yu, Ming'e.

    2015-08-01

    A series of Ce-doped V2O5/TiO2 catalysts synthesized by an ultrasound assisted impregnation method were employed to investigate simultaneous removal of elemental mercury (Hg0) and NO in lab-scale experiments. Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), X-ray diffractogram (XRD), and X-ray photoelectron spectroscopy (XPS) analyses were used to characterize the samples. Compared to TiO2 support, the catalytic performance of CeO2 doped on both TiO2 and V2O5/TiO2 catalysts have been improved. Remarkably, 1%V2O5-10% CeO2/TiO2 (V1Ce10Ti) exhibited the highest Hg0 oxidation efficiency of 81.55% at 250 °C with a desired NO removal efficiency under the same condition. Both the NO conversion and Hg0 oxidation efficiency were enhanced in the presence of O2. The activity was inhibited by the injection of NH3 with the increase of NH3/NO. When in the presence of 400 ppm SO2, Hg0 oxidation was slightly affected. Furthermore, Hg0 removal behavior under both oxidation and selective catalytic reduction (SCR) condition over V1Ce10Ti were well investigated to further probe into the feasibility of one single unit for multi-pollutants control in industry application. The existence of the redox cycle of V4+ + Ce4+ ? V5+ + Ce3+ in V2O5-CeO2/TiO2 catalyst could not only greatly improve the NO conversion, but also promote the oxidation of Hg0.

  15. Spin density matrix elements in exclusive $?$ electroproduction on $^1$H and $^2$H targets at 27.5 GeV beam energy

    E-print Network

    The HERMES Collaboration; A. Airapetian; N. Akopov; Z. Akopov; W. Augustyniak; A. Avetissian; H. P. Blok; A. Borissov; V. Bryzgalov; M. Capiluppi; G. P. Capitani; E. Cisbani; G. Ciullo; M. Contalbrigo; P. F. Dalpiaz; W. Deconinck; R. De Leo; E. De Sanctis; M. Diefenthaler; P. Di Nezza; M. Düren; M. Ehrenfried; G. Elbakian; F. Ellinghaus; E. Etzelmüller; R. Fabbri; L. Felawka; S. Frullani; D. Gabbert; G. Gapienko; V. Gapienko; F. Garibaldi; G. Gavrilov; V. Gharibyan; M. Hartig; D. Hasch; Y. Holler; I. Hristova; A. Ivanilov; H. E. Jackson; S. Joosten; R. Kaiser; G. Karyan; T. Keri; E. Kinney; A. Kisselev; V. Korotkov; V. Kozlov; P. Kravchenko; V. G. Krivokhijine; L. Lagamba; L. Lapikás; I. Lehmann; P. Lenisa; W. Lorenzon; B. -Q. Ma; D. Mahon; S. I. Manaenkov; Y. Mao; B. Marianski; H. Marukyan; A. Movsisyan; M. Murray; Y. Naryshkin; A. Nass; W. -D. Nowak; L. L. Pappalardo; R. Perez-Benito; A. Petrosyan; P. E. Reimer; A. R. Reolon; C. Riedl; K. Rith; A. Rostomyan; D. Ryckbosch; A. Schäfer; G. Schnell; K. P. Schüler; B. Seitz; T. -A. Shibata; M. Stahl; M. Stancari; M. Statera; E. Steffens; J. J. M. Steijger; S. Taroian; A. Terkulov; R. Truty; A. Trzcinski; M. Tytgat; Y. Van Haarlem; C. Van Hulse; V. Vikhrov; I. Vilardi; S. Wang; S. Yaschenko; S. Yen; D. Zeiler; B. Zihlmann; P. Zupranski

    2014-10-11

    Exclusive electroproduction of $\\omega$ mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of Q$^2$>1.0 GeV$^2$, 3.0 GeV < W < 6.3 GeV, and -t'< 0.2 GeV$^2$. Results on the angular distribution of the $\\omega$ meson, including its decay products, are presented. The data were accumulated with the HERMES forward spectrometer during the 1996-2007 running period using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio reveals that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are presented in projections of Q$^2$ or -t'. Violation of s-channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse $\\omega$ production by longitudinal and transverse virtual photons, $\\gamma^{*}_{L} \\to \\omega_{T}$ and $\\gamma^{*}_{T} \\to \\omega_{T}$, is determined for the first time. A hierarchy of helicity amplitudes is established, which mainly means that the unnatural-parity-exchange amplitude describing the $\\gamma^*_T \\to \\omega_T$ transition dominates over the two natural-parity-exchange amplitudes describing the $\\gamma^*_L \\to \\omega_L$ and $\\gamma^*_T \\to \\omega_T$ transitions, with the latter two being of similar magnitude. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions, which are of unnatural parity.

  16. Effect of small additional elements on DBTT of V–4Cr–4Ti irradiated at low temperatures

    Microsoft Academic Search

    Tamaki Shibayama; Ichiro Yamagata; Hideo Kayano; Chusei Namba

    1998-01-01

    As a part of a program to screen several V–4Cr–4Ti containing Si, Al and Y alloys and optimize the amounts of Si, Al and Y, the Charpy impact test of five kinds of V–4Cr–4Ti–Si–Al–Y alloys by an instrumented Charpy impact testing machine using miniaturized specimens (1.5 mm×1.5 mm×20 mm) have been conducted before and after neutron irradiation. Charpy impact specimens

  17. The origin and evolution of the odd-Z iron-peak elements Sc, V, Mn, and Co in the Milky Way stellar disk

    NASA Astrophysics Data System (ADS)

    Battistini, Chiara; Bensby, Thomas

    2015-05-01

    Context. Elements heavier than Li are produced in the interiors of stars. However, for many elements the exact production sites and the timescales on which they are dispersed into the interstellar medium are unknown. Having a clear picture on the origins of the elements is important for our ability to trace and understand the formation and chemical evolution of the Milky Way and its stellar populations. Aims: The aim of this study is to investigate the origin and evolution of Sc, V, Mn, and Co for a homogeneous and statistically significant sample of stars probing the different populations of the Milky Way, in particular the thin and thick disks. Methods: Using high-resolution spectra obtained with the MIKE, FEROS, SOFIN, FIES, UVES, and HARPS spectrographs, we determine Sc, V, Mn, and Co abundances for a large sample of F and G dwarfs in the solar neighborhood. The method is based on spectral synthesis and using one-dimensional, plane-parallel, local thermodynamic equilibrium (LTE) model stellar atmospheres calculated with the MARCS 2012 code. The non-LTE (NLTE) corrections from the literature were applied to Mn and Co. Results: We find that the abundance trends derived for Sc (594 stars), V (466 stars), and Co (567 stars) are very similar to what has been observed for the ?-elements in the thin and thick disks. On the contrary, Mn (569 stars) is generally underabundant relative to the Sun (i.e., [ Mn/Fe ] < 0) for [ Fe/H ] < 0. In addition, for Mn, when NLTE corrections are applied, the trend changes and is almost flat over the entire metallicity range of the stars in our sample (-2 ? [ Fe/H ] ? + 0.4). The [Sc/Fe]-[Fe/H] abundance trends show a small separation between the thin and thick disks, while for V and Co they completely overlap. For Mn there is a small difference in [Mn/Fe], but only when NLTE corrections are used. Comparisons with Ti as a reference element show flat trends for all the elements except for Mn that show well separated [Mn/Ti]-[Ti/H] trends for the thin and thick disks. Conclusions: The elements Sc and V present trends compatible with production from type II supernovae (SNII) events. In addition, Sc clearly shows a metallicity dependence for [ Fe/H ] < -1. Instead, Mn is produced in SNII events for [ Fe/H ] ? -0.4 and then type Ia supernovae start to produce Mn. Finally, Co appears to be produced mainly in SNII with suggestion of enrichment from hypernovae at low metallicities. This paper includes data gathered with the 6.5 m Magellan Telescopes located at the Las Campanas Observatory, Chile; the Nordic Optical Telescope (NOT) on La Palma, Spain; the Very Large Telescope (VLT) at the European Southern Observatory (ESO) on Paranal, Chile (ESO Proposal ID 69.B-0277 and 72.B-0179); the ESO 1.5-m, 2.2-m. and 3.6-m telescopes on La Silla, Chile (ESO Proposal ID 65.L-0019, 67.B-0108, 76.B-0416, 82.B-0610); and data from UVES Paranal Observatory Project (ESO DDT Program ID 266.D-5655).Full versions of Tables 2 and 5 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/A9Appendices are available in electronic form at http://www.aanda.org

  18. Coupled Transient Finite Element Simulation of Quench in Jefferson Lab's 11 GeV Super High Momentum Spectrometer Superconducting Magnets

    Microsoft Academic Search

    Eric Sun; Paul Brindza; Steven Lassiter; Michael Fowler; Edward Xu

    2010-01-01

    This paper presents coupled transient thermal and electromagnetic finite element analysis of quench in the Q2, Q3, and dipole superconducting magnets using Vector Fields Quench code. Detailed temperature distribution within coils and aluminum force collars were computed at each time step. Both normal (quench with dump resistor) and worst-case (quench without dump resistor) scenarios were simulated to investigate the maximum

  19. New elastic electron scattering factors for the elements for incident energies of 10, 40, 60, and 90 keV

    SciTech Connect

    Ross, A.W.; Fink, M.

    1986-12-01

    An improved set of scattering factors for all neutral elements has bee completed for inclusion in the new edition of the International Tables of X-ray Crystallography . These calculations are compared with the former electron scattering factors and the deviations between the two are discussed.(AIP)

  20. A Strategy for Preservice Teachers to Integrate Cultural Elements within Planning and Instruction: Cultural L.I.V.E.S.

    ERIC Educational Resources Information Center

    Salsbury, Denise E.

    2008-01-01

    The large percentages of teachers in the United States are white, middle class people who may not understand or identify their own cultural connections within the American culture, let alone elaborate their own ancestral cultural elements. Educators are expected to teach a diverse student population, and preservice teachers should be prepared to…

  1. Comparative mitochondrial genomics in zygomycetes: bacteria-like RNase P RNAs, mobile elements and a close source of the group I intron invasion in angiosperms

    PubMed Central

    Seif, Elias; Leigh, Jessica; Liu, Yu; Roewer, Ingeborg; Forget, Lise; Lang, B. Franz

    2005-01-01

    To generate data for comparative analyses of zygomycete mitochondrial gene expression, we sequenced mtDNAs of three distantly related zygomycetes, Rhizopus oryzae, Mortierella verticillata and Smittium culisetae. They all contain the standard fungal mitochondrial gene set, plus rnpB, the gene encoding the RNA subunit of the mitochondrial RNase P (mtP-RNA) and rps3, encoding ribosomal protein S3 (the latter lacking in R.oryzae). The mtP-RNAs of R.oryzae and of additional zygomycete relatives have the most eubacteria-like RNA structures among fungi. Precise mapping of the 5? and 3? termini of the R.oryzae and M.verticillata mtP-RNAs confirms their expression and processing at the exact sites predicted by secondary structure modeling. The 3? RNA processing of zygomycete mitochondrial mRNAs, SSU-rRNA and mtP-RNA occurs at the C-rich sequence motifs similar to those identified in fission yeast and basidiomycete mtDNAs. The C-rich motifs are included in the mature transcripts, and are likely generated by exonucleolytic trimming of RNA 3? termini. Zygomycete mtDNAs feature a variety of insertion elements: (i) mtDNAs of R.oryzae and M.verticillata were subject to invasions by double hairpin elements; (ii) genes of all three species contain numerous mobile group I introns, including one that is closest to an intron that invaded angiosperm mtDNAs; and (iii) at least one additional case of a mobile element, characterized by a homing endonuclease insertion between partially duplicated genes [Paquin,B., Laforest,M.J., Forget,L., Roewer,I., Wang,Z., Longcore,J. and Lang,B.F. (1997) Curr. Genet., 31, 380–395]. The combined mtDNA-encoded proteins contain insufficient phylogenetic signal to demonstrate monophyly of zygomycetes. PMID:15689432

  2. Effect of the main-group elements on the electronic structures and magnetic properties of Heusler alloys Mn 2NiZ (Z=In, Sn, Sb)

    NASA Astrophysics Data System (ADS)

    Luo, Hongzhi; Liu, Guodong; Feng, Zhongqiu; Li, Yangxian; Ma, Li; Wu, Guangheng; Zhu, Xiaoxi; Jiang, Chengbao; Xu, Huibin

    2009-12-01

    The magnetic properties and electronic structure of Mn 2NiZ (Z=In, Sn, Sb) have been studied. The magnetic structure of these alloys is mainly determined by the main-group element Z instead of the distance between the Mn atoms. Electronic structure calculations suggest that Mn 2NiIn and Mn 2NiSn are both ferrimagnets with antiparallel alignment between the Mn moments. But this antiferromagnetic coupling is weakened by the increasing number of valence electrons of the Z atoms. When it comes to Mn 2NiSb, a ferromagnetic coupling between the Mn atoms is observed. Mn 2NiSn and Mn 2NiSb have been synthesized successfully. Their Ms at 5 K agree well with the theoretical value.

  3. Cohesive energy, phonon spectra, and thermodynamic properties of elements with the structures A 1 , A 2 , A 3 , A 4 —Al, Cu, V, Ti, Mg, Si, and Sn

    Microsoft Academic Search

    N. N. Sirota; I. M. Sirota; T. M. Soshnina; T. D. Sokolovskii

    2001-01-01

    The dependences of the cohesive (atomization) energy on the interatomic distance for elements Al, Cu, Ti(A2), V, Mg, Ti(A3), Si, and Sn are calculated using methods based on the Thomas-Fermi-Dirac-Gambosh statistical atomic theory. The obtained\\u000a dependences are approximated by the Mie-Grneisen potential. The phonon spectra calculated on the basis of the Born-Krmn\\u000a model and the Born-Krmn-Blackman-de Lunay approach are used

  4. First principles DFT study of ferromagnetism in SnO{sub 2} induced by doped group 1A and 2A non-magnetic elements X (X=Li, Na, K, Be, Mg, Ca)

    SciTech Connect

    Chakraborty, Brahmananda, E-mail: brahma@barc.gov.in; Ramaniah, Lavanya M., E-mail: brahma@barc.gov.in [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-85 (India)

    2014-04-24

    Transition metal - free - ferromagnetism in diluted magnetic semiconductors (DMS) is of much current interest in the search for more efficient DMS materials for spintronic applications. Here, we report the results of our first principles density functional theory (DFT) study on impurity - induced ferromagnetism in non-magnetic SnO{sub 2} by a non-magnetic impurity. The impurities considered are sp-type of group 1A and 2A elements X (X = Li, Na, K, Be, Mg, Ca). Even a single atom of the group 1A elements makes the system magnetic, whereas for the group 2A elements Ca and Mg, a higher doping is required to induce ferromagnetism. For all the elements studied, the magnetic moment appears to increase with the doping concentration, at least at certain impurity separations, which is a positive indicator for practical applications.

  5. Correlation consistent basis sets for explicitly correlated wavefunctions: Pseudopotential-based basis sets for the post-d main group elements Ga-Rn

    NASA Astrophysics Data System (ADS)

    Hill, J. Grant; Peterson, Kirk A.

    2014-09-01

    New correlation consistent basis sets, cc-pVnZ-PP-F12 (n = D, T, Q), for all the post-d main group elements Ga-Rn have been optimized for use in explicitly correlated F12 calculations. The new sets, which include not only orbital basis sets but also the matching auxiliary sets required for density fitting both conventional and F12 integrals, are designed for correlation of valence sp, as well as the outer-core d electrons. The basis sets are constructed for use with the previously published small-core relativistic pseudopotentials of the Stuttgart-Cologne variety. Benchmark explicitly correlated coupled-cluster singles and doubles with perturbative triples [CCSD(T)-F12b] calculations of the spectroscopic properties of numerous diatomic molecules involving 4p, 5p, and 6p elements have been carried out and compared to the analogous conventional CCSD(T) results. In general the F12 results obtained with a n-zeta F12 basis set were comparable to conventional aug-cc-pVxZ-PP or aug-cc-pwCVxZ-PP basis set calculations obtained with x = n + 1 or even x = n + 2. The new sets used in CCSD(T)-F12b calculations are particularly efficient at accurately recovering the large correlation effects of the outer-core d electrons.

  6. Comments on the effect of Delta (1232 MeV)-hole excitation in quenching the gamow-teller matrix element

    Microsoft Academic Search

    A. Arima; T. Cheon; K. Shimizu; H. Hyuga; T. Suzuki

    1983-01-01

    The effect of the Delta-hole excitation in quenching the Gamow-Teller matrix element is investigated using the pion and rho-meson exchange potential. The contributions are found to be smaller than those given by the calculation using the Landau-Migdal type interaction with g'Delta = 0.6. The difference is found to be due to the choice of g'Delta. Discussions concerning the validity of

  7. Exogenously Added Human Group X Secreted Phospholipase A2 but Not the Group IB, IIA, and V Enzymes Efficiently Release Arachidonic Acid from Adherent Mammalian Cells

    Microsoft Academic Search

    Sofiane Bezzine; Rao S. Koduri; Emmanuel Valentin; Makoto Murakami; Ichiro Kudo; Farideh Ghomashchi; Martin Sadilek; Gerard Lambeau; Michael H. Gelba

    2000-01-01

    Mammalian secreted phospholipases A2 (sPLA2s) com- prise a group of at least eight enzymes, including the recently identified group X sPLA2. A bacterial expres- sion system was developed to produce human group X sPLA2 (hGX). Inhibition studies show that the sPLA2 inhibitor LY311727 binds modestly more tightly to hu- man group IIA sPLA2 than to hGX and that a pyrazole-

  8. Spin density matrix elements in exclusive ? 0 electroproduction on 1H and 2H targets at 27.5 GeV beam energy

    NASA Astrophysics Data System (ADS)

    Airapetian, A.; Akopov, N.; Akopov, Z.; Andrus, A.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetissian, E.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Böttcher, H.; Bonomo, C.; Borissov, A.; Brüll, A.; Bryzgalov, V.; Capiluppi, M.; Capitani, G. P.; Cisbani, E.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; de Leo, R.; Demey, M.; de Nardo, L.; de Sanctis, E.; Diefenthaler, M.; di Nezza, P.; Dreschler, J.; Düren, M.; Ehrenfried, M.; Elalaoui-Moulay, A.; Elbakian, G.; Ellinghaus, F.; Elschenbroich, U.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Funel, A.; Gabbert, D.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Gavrilov, G.; Gharibyan, V.; Giordano, F.; Gliske, S.; Grebeniouk, O.; Gregor, I. M.; Guler, H.; Hadjidakis, C.; Hartig, M.; Hasch, D.; Hasegawa, T.; Hesselink, W. H. A.; Hill, G.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hommez, B.; Hristova, I.; Iarygin, G.; Imazu, Y.; Ivanilov, A.; Izotov, A.; Jackson, H. E.; Jgoun, A.; Kaiser, R.; Keri, T.; Kinney, E.; Kisselev, A.; Kobayashi, T.; Kopytin, M.; Korotkov, V.; Kozlov, V.; Kravchenko, P.; Krivokhijine, V. G.; Lagamba, L.; Lamb, R.; Lapikás, L.; Lehmann, I.; Lenisa, P.; Liebing, P.; Linden-Levy, L. A.; Lorenzon, W.; Lu, S.; Lu, X.-R.; Ma, B.-Q.; Maiheu, B.; Makins, N. C. R.; Manaenkov, S. I.; Mao, Y.; Marianski, B.; Marukyan, H.; Mexner, V.; Miller, C. A.; Miyachi, Y.; Muccifora, V.; Murray, M.; Mussgiller, A.; Nagaitsev, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; Nowak, W.-D.; Osborne, A.; Pappalardo, L. L.; Perez-Benito, R.; Pickert, N.; Raithel, M.; Reggiani, D.; Reimer, P. E.; Reischl, A.; Reolon, A. R.; Riedl, C.; Rith, K.; Rock, S. E.; Rosner, G.; Rostomyan, A.; Rubacek, L.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanjiev, I.; Schäfer, A.; Schnell, G.; Schüler, K. P.; Seitz, B.; Shearer, C.; Shibata, T.-A.; Shutov, V.; Stancari, M.; Statera, M.; Steffens, J. E.; Steijger, J. J. M.; Stenzel, H.; Stewart, J.; Stinzing, F.; Streit, J.; Tait, P.; Taroian, S.; Tchuiko, B.; Terkulov, A.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; van der Nat, P. B.; van der Steenhoven, G.; van Haarlem, Y.; van Hulse, C.; Varanda, M.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Vogel, C.; Wang, S.; Yaschenko, S.; Ye, H.; Ye, Y.; Ye, Z.; Yen, S.; Yu, W.; Zeiler, D.; Zihlmann, B.; Zupranski, P.

    2009-08-01

    Spin Density Matrix Elements (SDMEs) describing the angular distribution of exclusive ? 0 electroproduction and decay are determined in the HERMES experiment with 27.6 GeV beam energy and unpolarized hydrogen and deuterium targets. Eight (fifteen) SDMEs that are related (unrelated) to the longitudinal polarization of the beam are extracted in the kinematic region 1< Q 2<7 GeV2, 3.0< W<6.3 GeV, and - t<0.4 GeV2. Within the given experimental uncertainties, a hierarchy of relative sizes of helicity amplitudes is observed. Kinematic dependences of all SDMEs on Q 2 and t are presented, as well as the longitudinal-to-transverse ? 0 electroproduction cross-section ratio as a function of Q 2. A small but statistically significant deviation from the hypothesis of s-channel helicity conservation is observed. An indication is seen of a contribution of unnatural-parity-exchange amplitudes; these amplitudes are naturally generated with a quark-exchange mechanism.

  9. The UV/optical spectra of the type Ia supernova SN 2010jn: A bright supernova with outer layers rich in iron-group elements

    E-print Network

    Hachinger, S; Sullivan, M; Ellis, R; Maguire, K; Gal-Yam, A; Howell, D A; Nugent, P E; Baron, E; Arcavi, I; Bersier, D; Dilday, B; James, P; Kasliwal, M M; Kulkarni, S R; Ofek, E O; Laher, R R; Parrent, J; Surace, J; Walker, E S

    2012-01-01

    Radiative transfer studies of Type Ia supernovae (SNe Ia) hold the promise of constraining both the time-dependent density profile of the SN ejecta and its stratification by element abundance which, in turn, may discriminate between different explosion mechanisms and progenitor classes. Here we present a detailed analysis of Hubble Space Telescope ultraviolet (UV) and ground-based optical spectra and light curves of the SN Ia SN 2010jn (PTF10ygu). SN 2010jn was discovered by the Palomar Transient Factory (PTF) 15 days before maximum light, allowing us to secure a time-series of four UV spectra at epochs from -11 to +5 days relative to B-band maximum. The photospheric UV spectra are excellent diagnostics of the iron-group abundances in the outer layers of the ejecta, particularly those at very early times. Using the method of 'Abundance Tomography' we have derived iron-group abundances in SN 2010jn with a precision better than in any previously studied SN Ia. Optimum fits to the data can be obtained if burned ...

  10. Ectomycorrhizal Influence on Particle Size, Surface Structure, Mineral Crystallinity, Functional Groups, and Elemental Composition of Soil Colloids from Different Soil Origins

    PubMed Central

    Li, Yanhong; Wang, Huimei; Wang, Wenjie; Yang, Lei; Zu, Yuangang

    2013-01-01

    Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus) and soil colloids from dark brown forest soil (a good loam) and saline-alkali soil (heavily degraded soil), we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P > 0.05). These increased the amount of variable functional groups (O–H stretching and bending, C–H stretching, C=O stretching, etc.) by 3–26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz) by 40–300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12–35% decreases in most functional groups, 15–55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P < 0.05). These different responses sharply decreased element ratios (C?:?O, C?:?N, and C?:?Si) in soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil. PMID:23766704

  11. Cosmic-ray elemental abundances from 1 to 10 GeV per amu for boron through nickel

    NASA Technical Reports Server (NTRS)

    Dwyer, Robert; Meyer, Peter

    1987-01-01

    The relative abundances of cosmic-ray nuclei in the charge range boron through nickel over the energy range 1-10 GeV per amu were measured with a balloon-borne detector. The instrument consists of a scintillation and Cerenkov counter telescope with a multiwire proportional chamber hodoscope and has been flown in four high-altitude balloon flights. Good charge resolution (sigma = 0.2 charge units at iron) and high statistical accuracy have been achieved. These data are used to derive the energy dependence of the leakage path length using the leaky box model of propagation and confinement in the galaxy. This energy dependence is found to be best fit by lambda = E(tot) exp -n, where n = 0.49 + or - 0.06 over 1-10 GeV per amu. Relative abundances at the source are consistent with an energy-independent composition.

  12. Unipotent elements in algebraic groups

    E-print Network

    Clarke, Matthew Charles

    2012-01-10

    generalised Gelfand-Graev representation of GF . Under the assumption that G has a connected centre, we show that the dimension of the endomorphism algebra of ?u is a polynomial in q (the order of the associated finite field), with degree given by dim...

  13. Lanthanum resulted in unbalance of nutrient elements and disturbance of cell proliferation cycles in V. faba L. seedlings.

    PubMed

    Wang, Chengrun; Lu, Xianwen; Tian, Yuan; Cheng, Tao; Hu, Lingling; Chen, Fenfen; Jiang, Chuanjun; Wang, Xiaorong

    2011-11-01

    Effects of lanthanum (La) on mineral nutrients, cell cycles, and root lengthening have been little reported. The present work investigated these physiological responses in roots of Vicia faba seedlings cultivated in La3+-contained solutions for 15 days. The results showed that the increasing contents of La in the roots and leaves contributed to disbalances of contents of Ca, Fe, Cu, Zn, Mg, Mn, P, and K elements, and potential redistributions of some elements in the roots and leaves. These disbalances might be involved in the subsequent alteration of cell cycle phases in the root tips. Low-dose promotion and high-dose inhibition (Hormetic effects) were demonstrated as the dose responses of G0/G1-, S- or G2/M-phase ratios. The cell cycles were most probably arrested at G1/S interphase by La3+ in the root tips. The fact that the root lengths were not consistent with the changes of cell cycle phases suggested that the cell proliferation activities might be masked by other factors (e.g., cell expansion) under long-time exposure to La3+. PMID:21207184

  14. A multicenter, double-blind comparison of i.v. and oral administration of ondansetron plus dexamethasone for acute cisplatin-induced emesis. Ondansetron Acute Emesis Study Group.

    PubMed

    Krzakowski, M; Graham, E; Goedhals, L; Joly, F; Pawlicki, M; Rapoport, B; Yelle, L; Lees, J; McQuade, B

    1998-08-01

    A total of 530 patients were treated in this multicenter, double-blind, double-dummy, parallel group study to compare the anti-emetic efficacy and safety of a once daily ondansetron oral regimen with a once daily i.v. dosing regimen over a 24 h period, administered to patients prior to receiving cisplatin (50 mg/m2 or greater) chemotherapy. Patients were randomized to receive a single dose of ondansetron plus dexamethasone given either orally (ondansetron 24 mg and dexamethasone 12 mg, n=262) or i.v. (ondansetron 8 mg and dexamethasone 20 mg, n=268). Complete control of emesis (i.e. no emetic episodes, no rescue and no premature withdrawal) was achieved for 85% of patients (224 of 262) in the oral group and 83% (223 of 268) in the i.v. group. No nausea was reported in 70% of patients in the oral group and 68% in the i.v. group. There were no statistically significant differences between the two groups for any of the assessments of efficacy, which included time to first emetic episode, number of emetic episodes and the worst grade of nausea occurring over the 24 h study period. Once daily ondansetron oral and i.v., in combination with dexamethasone, was well tolerated in this study. In conclusion, once daily oral ondansetron 24 mg plus dexamethasone is equally effective in the control of emesis and nausea induced by highly emetogenic chemotherapy as once daily ondansetron 8 mg i.v. plus dexamethasone. PMID:9773802

  15. Group-V mixing effects in the structural and optical properties of ( ZnSi )1\\/2 P1\\/4 As3\\/4

    Microsoft Academic Search

    A. A. Leitão; R. B. Capaz

    2004-01-01

    We present ab initio total energy and band structure calculations based on density funtional theory within the local density aproximation on group-V mixing effects in the optoelectronic material ( ZnSi )1\\/2 P1\\/4 As3\\/4 . This compound has been recently proposed by theoretical design as an optically active material in the 1.5 mum ( 0.8 eV ) fiber optics frequency window

  16. Measurement of the t-channel single-top-quark production cross section and of the | V tb| CKM matrix element in pp collisions at = 8 TeV

    NASA Astrophysics Data System (ADS)

    Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knünz, V.; Krammer, M.; Krätschmer, I.; Liko, D.; Mikulec, I.; Rabady, D.; Rahbaran, B.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Bansal, M.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Knutsson, A.; Luyckx, S.; Ochesanu, S.; Roland, B.; Rougny, R.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Daci, N.; Heracleous, N.; Kalogeropoulos, A.; Keaveney, J.; Kim, T. J.; Lowette, S.; Maes, M.; Olbrechts, A.; Python, Q.; Strom, D.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Caillol, C.; Clerbaux, B.; De Lentdecker, G.; Favart, L.; Gay, A. P. R.; Grebenyuk, A.; Léonard, A.; Marage, P. E.; Mohammadi, A.; Perniè, L.; Reis, T.; Seva, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Adler, V.; Beernaert, K.; Benucci, L.; Cimmino, A.; Costantini, S.; Crucy, S.; Dildick, S.; Fagot, A.; Garcia, G.; Klein, B.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Salva Diblen, S.; Sigamani, M.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Beluffi, C.; Bruno, G.; Castello, R.; Caudron, A.; Ceard, L.; Da Silveira, G. G.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Jez, P.; Komm, M.; Lemaitre, V.; Liao, J.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Popov, A.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Vizan Garcia, J. M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Alves, G. A.; Correa Martins, M.; Dos Reis Martins, T.; Pol, M. E.; Aldá, W. L.; Carvalho, W.; Chinellato, J.; Custódio, A.; Da Costa, E. M.; De Jesus Damiao, D.; De Oliveira Martins, C.; Fonseca De Souza, S.; Malbouisson, H.; Malek, M.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Prado Da Silva, W. L.; Santaolalla, J.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Marinov, A.; Piperov, S.; Rodozov, M.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Hadjiiska, R.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Du, R.; Jiang, C. H.; Liang, D.; Liang, S.; Plestina, R.; Tao, J.; Wang, X.; Wang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, Y.; Li, Q.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Zhang, L.; Zou, W.; Avila, C.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; Gomez Moreno, B.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Kadija, K.; Luetic, J.; Mekterovic, D.; Morovic, S.; Sudic, L.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Bodlak, M.; Finger, M.; Finger, M.; Assran, Y.; Ellithi Kamel, A.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Murumaa, M.; Raidal, M.; Tiko, A.; Eerola, P.; Fedi, G.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Nayak, A.; Rander, J.; Rosowsky, A.; Titov, M.; Baffioni, S.; Beaudette, F.; Busson, P.; Charlot, C.; Dahms, T.; Dalchenko, M.; Dobrzynski, L.; Filipovic, N.; Florent, A.; Granier de Cassagnac, R.; Mastrolorenzo, L.; Miné, P.; Mironov, C.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Paganini, P.; Salerno, R.; Sauvan, J. b.; Sirois, Y.; Veelken, C.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Chabert, E. C.; Collard, C.; Conte, E.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Goetzmann, C.; Le Bihan, A.-C.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Beaupere, N.; Boudoul, G.; Brochet, S.; Carrillo Montoya, C. A.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Ruiz Alvarez, J. D.; Sabes, D.; Sgandurra, L.; Sordini, V.; Vander Donckt, M.; Verdier, P.; Viret, S.; Xiao, H.; Tsamalaidze, Z.; Autermann, C.

    2014-06-01

    Measurements are presented of the t-channel single-top-quark production cross section in proton-proton collisions at = 8 TeV. The results are based on a data sample corresponding to an integrated luminosity of 19.7 fb-1 recorded with the CMS detector at the LHC. The cross section is measured inclusively, as well as separately for top (t) and antitop , in final states with a muon or an electron. The measured inclusive t-channel cross section is ? t-ch. = 83 .6 ± 2 .3 (stat.) ± 7 .4 (syst.) pb. The single t and cross sections are measured to be ? t-ch.( t) = 53 .8 ± 1 .5 (stat.) ± 4 .4 (syst.) pb and ? t-ch. = 27 .6 ± 1 .3 (stat.) ± 3 .7 (syst.) pb, respectively. The measured ratio of cross sections is R t-ch. = ? t-ch.(t) /? t-ch. = 1 .95 ± 0 .10 (stat.) ± 0 .19 (syst.), in agreement with the standard model prediction. The modulus of the Cabibbo-Kobayashi-Maskawa matrix element V tb is extracted and, in combination with a previous CMS result at = 7 TeV, a value | V tb| = 0 .998 ± 0 .038 (exp.) ± 0 .016 (theo.) is obtained. [Figure not available: see fulltext.

  17. Electronic properties of transition-metal nitrides: The group-V and group-VI nitrides VN, NbN, TaN, CrN, MoN, and WN

    Microsoft Academic Search

    D. A. Papaconstantopoulos; W. E. Pickett; B. M. Klein; L. L. Boyer

    1985-01-01

    Motivated by the prediction that B1-structure MoN is a high-temperature superconductor, we present self-consistent augmented-plane-wave calculations of the electronic structure of the group-V and group-VI transition-metal nitrides VN, NbN, TaN, CrN, MoN, and WN. Comparisons of the energy bands, densities of states, and general bonding characteristics are made within this group, as well as with previously calculated transition-metal carbides. The

  18. First-principles electronic structure and formation energies of group V and VII impurities in the ?-Fe{sub 2}O{sub 3} alloys

    SciTech Connect

    Xia, Congxin, E-mail: cxia@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States); International Laboratory for Quantum Functional Materials of Henan, Zhengzhou University, Zhengzhou, Henan 450001 (China); Jia, Yu [International Laboratory for Quantum Functional Materials of Henan, Zhengzhou University, Zhengzhou, Henan 450001 (China); Zhang, Qiming [Department of Physics, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2014-09-21

    Based on density functional theory, the electronic structures, formation energy, and transition level of the selected group V and VII impurities in ?-Fe{sub 2}O{sub 3} are investigated by means of first-principles methods. Numerical results show that the group V and VII atoms-doped ?-Fe{sub 2}O{sub 3} can be energetically favorable under the Fe-rich condition. Group V atom substituting O atom can induce the acceptor impurity level, while the deep donor impurity states are formed inside the band gap when group VII atom substitute O atom in the ?-Fe{sub 2}O{sub 3}. Moreover, our results show that halogen atom F substituting O atom should be very easy in the ?-Fe{sub 2}O{sub 3}. In addition, our results also show that for both group V and VII atom-doped ?-Fe{sub 2}O{sub 3}, the upper sides of valence band are modified obviously, while the conduction band edge does not change.

  19. Chemical studies of L chondrites. V: compositional patterns for 49 trace elements in 14 L4-6 and 7 LL4-6 falls

    NASA Astrophysics Data System (ADS)

    Friedrich, Jon M.; Wang, Ming-Sheng; Lipschutz, Michael E.

    2003-07-01

    To study compositional trends associated with open-system thermal metamorphism and shock-induced collisional breakup of L4-6 chondrite parent(s), we used inductively coupled plasma mass spectrometry and radiochemical neutron activation analysis to determine 49 trace elements in 62 falls. Trends for the 49 elements, especially of the 14 rare earth elements in 5 members of a putative L/LL group (Bjurböle, Cynthiana, Holbrook, Knyahinya, Sultanpur) and 9 additional L chondrites (Aïr, Aumieres, Bachmut, Forksville, Kandahar, Kiel, Milean, Narellan, Santa Isabel) differed markedly from those in the remaining normal 46 samples. Here, we report the data for the 14 L and putative L/LL chondrites and 7 LL (Appley Bridge, Athens, Bandong, Ensisheim, Mangwendi, Olivenza, Soko-Banja), analyzed to test the affinity of the putative L/LL suite to well-characterized LL chondrites. Compositional trends of the 14 atypical L chondrites (including Aïr's unique and possibly contaminated signature) and Mangwendi, an LL6 chondrite, indicate that each is compositionally unrepresentative of well-sampled, whole-rock chondrites. Indeed, half of the unrepresentative chondrites were ? 2-g samples. Compositionally, members of the putative L/LL chondrites demonstrate no affinities to normal LL chondrite falls. To establish compositional trends accompanying open-system, thermal episodes involving the L chondrite parent(s), we should ignore data for the 14 unrepresentative L chondrites reported here.

  20. Ab initio calculation of natural band offsets of all group IV, II-VI and III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Wei, Su-Huai; Walsh, Aron; Li, Yong-Hua; Gong, Xingao

    2010-03-01

    The natural band offset between semiconductors is one of the most fundamental properties in materials physics. It is a necessary quantity to assess charge transport and quantum confinement, and is of particular relevance to the design of optoelectronic devices which feature an interface between two or more materials. However, in the past, the natural band offset calculations were based on the assumption that certain reference levels (core levels, average Coulomb potentials, etc.) have zero absolute deformation potential, and thus align between the bulk and heterostructures. In this study [1], using an all-electron band structure approach, we have systematically calculated the natural band offsets between all group IV, III-V and II-VI semiconductor compounds, taking into account the deformation potential of the core states. This revised approach removes assumptions regarding the deformation potential of the reference levels, and offers a more reliable prediction of the `natural' unstrained offsets. Comparison is made to experimental work, where a noticeable improvement is found compared to previous methodologies. [1] Y.-H. Li et al., Appl. Phys. Lett. 94, 212109 (2009).

  1. Top quark mass measurement in the tt all hadronic channel using a matrix element technique in pp collisions at {radical}(s)=1.96 TeV

    SciTech Connect

    Aaltonen, T.; Maki, T.; Mehtala, P.; Orava, R.; Remortel, N. van [Division of High Energy Physics, Department of Physics, University of Helsinki and Helsinki Institute of Physics, FIN-00014, Helsinki (Finland); Adelman, J.; Brubaker, E.; Fedorko, W. T.; Grosso-Pilcher, C.; Kim, Y. K.; Krop, D.; Kwang, S.; Lee, H. S.; Paramonov, A. A.; Schmidt, M. A.; Shiraishi, S.; Shochet, M.; Wilbur, S.; Wolfe, C.; Yang, U. K. [Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637 (United States)] (and others)

    2009-04-01

    We present a measurement of the top quark mass in the all hadronic channel (tt{yields}bbq{sub 1}q{sub 2}q{sub 3}q{sub 4}) using 943 pb{sup -1} of pp collisions at {radical}(s)=1.96 TeV collected at the CDF II detector at Fermilab (CDF). We apply the standard model production and decay matrix element (ME) to tt candidate events. We calculate per-event probability densities according to the ME calculation and construct template models of signal and background. The scale of the jet energy is calibrated using additional templates formed with the invariant mass of pairs of jets. These templates form an overall likelihood function that depends on the top quark mass and on the jet energy scale (JES). We estimate both by maximizing this function. Given 72 observed events, we measure a top quark mass of 171.1{+-}3.7(stat+JES){+-}2.1(syst) GeV/c{sup 2}. The combined uncertainty on the top quark mass is 4.3 GeV/c{sup 2}.

  2. The origin and evolution of the odd-Z iron-peak elements Sc, V, Mn, and Co in the Milky Way stellar disk

    E-print Network

    Battistini, Chiara

    2015-01-01

    AIMS: The aim of this study is to investigate the origin and evolution of Sc, V, Mn, and Co for a homogeneous and statistically significant sample of stars probing the different populations of the Milky Way, in particular the thin and thick disks. METHODS: Using high-resolution spectra obtained with MIKE, FEROS, SOFIN, FIES, UVES and HARPS spectrographs, we determine Sc, V, Mn, and Co abundances for a large sample of F and G dwarfs in Solar neighbourhood. The method is based on spectral synthesis and using one-dimensional (1-D), plane-parallel, LTE model stellar atmospheres calculated with the MARCS 2012 code. NLTE corrections from literature were applied to Mn and Co. RESULTS: We find that the abundance trends derived for Sc (594 stars), V (466 stars), and Co (567 stars) are very similar to what has been observed for the alpha-elements in the thin and thick disks. On the contrary Mn (569 stars) is generally underabundant relative to the Sun (i.e. [Mn/Fe]Mn, when NLTE correct...

  3. Revised Energy Spectra for Primary Elements, H - Si, above 50 GeV from the ATIC-2 Science Flight

    NASA Technical Reports Server (NTRS)

    Wefel, J. P.; Adams, J. H., Jr.; Ahn, H. S.; Bashindzhagyan, G. L.; Chang, J.; Christl, M.; Fazely, A. R.; Ganel, O.; Gunashingha, R. M.; Guzik, T. G.; Isbert, J.; Kim, K. C.; Kouznetsov, E. N.; Panasyuk, M. I.; Panov, A. D.; Schmidt, W. K. H.; Seo, E. S.; Sokolskaya, N. V.; Watts, J. W.; Wu, J.; Zatsepin, V. I.

    2007-01-01

    The Advanced Thin Ionization Calorimeter (ATIC) long duration balloon experiment had a successful science flight accumulating 18 days of data (12/02 - 1/03) during a single circumnavigation in Antarctica. ATIC measures the energy spectra of elements from H to Fe in primary cosmic rays using a fully active Bismuth Germanate calorimeter preceded by a carbon target, with embedded scintillator hodoscopes, and a silicon matrix charge detector at the top. Preliminary results from ATIC have been reported in previous conferences. The revised results reported here are derived from a new analysis of the data with improved charge resolution, lower background and revised energy calibration. The raw energy deposit spectra are de-convolved into primary energy spectra and extrapolated to the top of the atmosphere. We compare these revised results to previous data and comment upon the astrophysical interpretation of the results.

  4. The mineralogy and mineral associations of platinum group elements and gold in the Platreef at Zwartfontein, Akanani Project, Northern Bushveld Complex, South Africa

    NASA Astrophysics Data System (ADS)

    van der Merwe, Frits; Viljoen, Fanus; Knoper, Mike

    2012-09-01

    The mineralogy of the platinum-group elements (PGE), and gold, in the Platreef of the Bushveld Complex, was investigated using an FEI Mineral Liberation Analyser. Polished sections were prepared from 171 samples collected from two boreholes, for the in-situ examination of platinum group minerals (PGM). PGM and gold minerals encountered include maslovite (PtBiTe, 32 area% of total PGM), kotulskite (Pd(BiTe), 17 %), isoferroplatinum (Pt3Fe, 15 %), sperrylite (PtAs2, 11 %), cooperite (PtS, 5 %), moncheite (PtTe2; 5 %), electrum (AuAg; 5 %), michenerite (PdBiTe; 3 %), Pd alloys (Pd, Sb, Sn; 3 %), hollingworthite ((Rh,Pt)AsS; 2 %), as well as minor (all <1 area% of total PGM) merenskyite (PdBiTe2), laurite (RuS2), rustenburgite (Pt0.4Pd0.4Sn0.2), froodite (PdBi2), atokite (Pd0.5Pt0.3Sn0.2), stumpflite (PtSb), plumbopalladinite (Pd3Pb2), and zvyagintsevite (Pd3Pb). An observed association of all PGM with base metal sulfides (BMS), and a pronounced association of PGE tellurides, arsenides and Pd&Pt alloys with secondary silicates, is consistent with the remobilisation and recrystallisation of some of the PGM's during hydrothermal alteration and serpentinisation subsequent to their initial (primary) crystallisation from BMS (e.g. Godel et al. J Petrol 48:1569-1604, 2007; Hutchinson and McDonald Appl Earth Sci (Trans Inst Min Metall B) 114:B208-224, 2008).

  5. Determination of the platinum - Group elements (PGE) and gold (Au) in manganese nodule reference samples by nickel sulfide fire-assay and Te coprecipitation with ICP-MS

    USGS Publications Warehouse

    Balaram, V.; Mathur, R.; Banakar, V.K.; Hein, J.R.; Rao, C.R.M.; Gnaneswara, Rao T.; Dasaram, B.

    2006-01-01

    Platinum group elements (PGE) and Au data in polymetallic oceanic ferromanganese nodule reference samples and crust samples obtained by inductively coupled plasma mass spectrometry (ICP-MS), after separation and pre-concentration by nickel sulfide fire-assay and Te coprecipitation, are presented. By optimizing several critical parameters such as flux composition, matrix matching calibration, etc., best experimental conditions were established to develop a method suitable for routine analysis of manganese nodule samples for PGE and Au. Calibrations were performed using international PGE reference materials, WMG-1 and WMS-1. This improved procedure offers extremely low detection limits in the range of 0.004 to 0.016 ng/g. The results obtained in this study for the reference materials compare well with previously published data wherever available. New PGE data arc also provided on some international manganese nodule reference materials. The analytical methodology described here can be used for the routine analysis of manganese nodule and crust samples in marine geochemical studies.

  6. Ion beam synthesis and n-type doping of group III-Nx-V1-x alloys

    NASA Astrophysics Data System (ADS)

    Yu, K. M.

    2002-08-01

    Investigations on the synthesis of group III-Nx-V1-x alloy including GaNxAs1-x, InNxP1-x and AlyGa1-yNxAs1-x using N ion implantation followed by rapid thermal annealing are reviewed. The fundamental band-gap energy for the ion beam synthesized III-Nx-V1-x alloys is found to decrease with increasing N-implantation dose and can be quantitatively described by the anticrossing interaction between the localized N-states and the extended states of the semiconductor matrix. N activation efficiencies in these N ion synthesized alloy films are found to be low, ~10% for GaNxAs1-x and ~20% for InNxP1-x. A preliminary study showed that using pulsed laser melting followed by rapid thermal annealing greatly enhanced the N activation efficiency (~50%) in N-implanted GaAs. The N-induced conduction band modification also results in an enhancement of the maximum free electron concentration in GaNxAs1-x. A maximum free electron concentration as high as 7 × 1019 cm-3 was observed in heavily Se-doped Ga1-3xIn3xNxAs1-x (x = 0.033) films, more than 20 times larger than that observed in GaAs films grown under similar conditions. A similar increase in free electron concentration was also achieved in a S-implanted GaNxAs1-x thin film. Combining the ion synthesis of diluted nitrides and S implantation doping techniques, we realized a large increase in the electrical activation of S co-implanted with N in GaAs within a thin near-surface region (~500 Å), indicating the formation of a heavily doped thin diluted GaNxAs1-x alloy layer with x ~ 0.3%. This result has important practical implications on the fabrication of low-resistance, non-alloyed ohmic contacts to n-type GaAs.

  7. Effects of Long-lived 10 MeV Scale Sterile Neutrino on Primordial Elemental Abundances and Effective Neutrino Number

    E-print Network

    Hiroyuki Ishida; Motohiko Kusakabe; Hiroshi Okada

    2014-08-11

    The primordial lithium abundance inferred from observations of metal-poor stars is ~3 times smaller than the theoretical value in standard big bang nucleosynthesis (BBN) model. We assume a simple model including a sterile neutrino nu_H with mass of O(10) MeV which decays long after BBN. We then investigate cosmological effects of a sterile neutrino decay. We formulate the injection spectrum of nonthermal photons induced by electrons and positrons generated at the nu_H decay, as a function of the nu_H mass and the photon temperature. We then consistently solve (1) the cosmic thermal history, (2) nonthermal nucleosynthesis induced by the nonthermal photons, (3) the baryon-to-photon ratio eta, and (4) the effective neutrino number N_eff. Amounts of energy injection at the nu_H decay are constrained from limits on primordial D and 7Li abundances, the N_eff value, and the cosmic microwave background energy spectrum. We find that 7Be is photodisintegrated and the Li problem is partially solved for the lifetime 10^4-10^5 s and the mass >~ 14 MeV. 7Be destruction by more than a factor of 3 is not possible because of an associated D over-destruction. In the parameter region, the eta value is decreased slightly, while the N_eff value is increased by a factor of <~ 1. In this study, errors in photodisintegration cross sections of 7Be(g, a)3He and 7Li(g, a)3H that have propagated through literatures are corrected. It is then found that the new photodisintegration rates are 2.3 to 2.5 times smaller than the old rates, so that efficiencies of 7Be and 7Li photodisintegration are significantly smaller.

  8. Coupled Transient Finite Element Simulation of Quench in Jefferson Lab's 11 GeV Super High Momentum Spectrometer Superconducting Magnets

    SciTech Connect

    E. Sun, P. Brindza, S. Lassiter, M. Fowler, E. Xu

    2010-06-01

    This paper presents coupled transient thermal and electromagnetic finite element analysis of quench in the Q2, Q3, and dipole superconducting magnets using Vector Fields Quench code. Detailed temperature distribution within coils and aluminum force collars were computed at each time step. Both normal (quench with dump resistor) and worst-case (quench without dump resistor) scenarios were simulated to investigate the maximum temperatures. Two simulation methods were utilized, and their algorithms, implementation, advantages, and disadvantages are discussed. The first method simulated the coil using nonlinear transient thermal analysis directly linked with the transient circuit analysis. It was faster because only the coil was meshed and no eddy current was modeled. The second method simulated the whole magnet including the coil, the force collar, and the iron yoke. It coupled thermal analysis with transient electromagnetic field analysis which modeled electromagnetic fields including eddy currents within the force collar. Since eddy currents and temperature in the force collars were calculated in various configurations, segmentation of the force collars was optimized under the condition of fast discharge.

  9. Group-V mixing effects in the structural and optical properties of ( ZnSi )1/2 P1/4 As3/4

    NASA Astrophysics Data System (ADS)

    Leitão, A. A.; Capaz, R. B.

    2004-08-01

    We present ab initio total energy and band structure calculations based on density funtional theory within the local density aproximation on group-V mixing effects in the optoelectronic material ( ZnSi )1/2 P1/4 As3/4 . This compound has been recently proposed by theoretical design as an optically active material in the 1.5 ?m ( 0.8 eV ) fiber optics frequency window and with a monolithic integration with the Si ( 001 ) surface. Our results indicate that alloy formation in the group-V planes would likely occur at typical growth conditions. In addition, desired features such as in-plane lattice constant and energy gap are virtually unchanged and the optical oscillator strength for band-to-band transitions is increased by a factor of 6 due to alloying.

  10. Platinum-group element constraints on source composition and magma evolution of the Kerguelen Plateau using basalts from ODP Leg 183

    NASA Astrophysics Data System (ADS)

    Chazey, William J.; Neal, Clive R.

    2005-10-01

    Seventeen basalts from Ocean Drilling Program (ODP) Leg 183 to the Kerguelen Plateau (KP) were analyzed for the platinum-group elements (PGEs: Ir, Ru, Rh, Pt, and Pd), and 15 were analyzed for trace elements. Relative concentrations of the PGEs ranged from ˜0.1 (Ir, Ru) to ˜5 (Pt) times primitive mantle. These relatively high PGE abundances and fractionated patterns are not accounted for by the presence of sulfide minerals; there are only trace sulfides present in thin-section. Sulfur saturation models applied to the KP basalts suggest that the parental magmas may have never reached sulfide saturation, despite large degrees of partial melting (˜30%) and fractional crystallization (˜45%). First order approximations of the fractionation required to produce the KP basalts from an ˜30% partial melt of a spinel peridotite were determined using the PELE program. The model was adapted to better fit the physical and chemical observations from the KP basalts, and requires an initial crystal fractionation stage of at least 30% olivine plus Cr-spinel (49:1), followed by magma replenishment and fractional crystallization (RFC) that included clinopyroxene, plagioclase, and titanomagnetite (15:9:1). The low Pd values ([Pd/Pt] pm < 1.7) for these samples are not predicted by currently available K d values. These Pd values are lowest in samples with relatively higher degrees of alteration as indicated by petrographic observations. Positive anomalies are a function of the behavior of the PGEs; they can be reproduced by Cr-spinel, and titanomagnetite crystallization, followed by titanomagnetite resorption during the final stages of crystallization. Our modeling shows that it is difficult to reproduce the PGE abundances by either depleted upper or even primitive mantle sources. Crustal contamination, while indicated at certain sites by the isotopic compositions of the basalts, appears to have had a minimal affect on the PGEs. The PGE abundances measured in the Kerguelen Plateau basalts are best modeled by melting a primitive mantle source to which was added up to 1% of outer core material, followed by fractional crystallization of the melt produced. This reproduces both the abundances and patterns of the PGEs in the Kerguelen Plateau basalts. An alternative model for outer core PGE abundances requires only 0.3% of outer core material to be mixed into the primitive mantle source. While our results are clearly model dependent, they indicate that an outer core component may be present in the Kerguelen plume source.

  11. On Some Algebraic and Combinatorial Properties of Dunkl Elements

    NASA Astrophysics Data System (ADS)

    Kirillov, Anatol N.

    2012-11-01

    We introduce and study a certain class of nonhomogeneous quadratic algebras together with the special set of mutually commuting elements inside of each, the so-called Dunkl elements. We describe relations among the Dunkl elements. This result is a further generalization of similar results obtained in [S. Fomin and A. N. Kirillov, Quadratic algebras, Dunkl elements and Schubert calculus, in Advances in Geometry (eds. J.-S. Brylinski, V. Nistor, B. Tsygan and P. Xu), Progress in Math. Vol. 172 (Birkhäuser Boston, Boston, 1995), pp. 147-182, A. Postnikov, On a quantum version of Pieri's formula, in Advances in Geometry (eds. J.-S. Brylinski, R. Brylinski, V. Nistor, B. Tsygan and P. Xu), Progress in Math. Vol. 172 (Birkhäuser Boston, 1995), pp. 371-383 and A. N. Kirillov and T. Maenor, A Note on Quantum K-Theory of Flag Varieties, preprint]. As an application we describe explicitly the set of relations among the Gaudin elements in the group ring of the symmetric group, cf. [E. Mukhin, V. Tarasov and A. Varchenko, Bethe Subalgebras of the Group Algebra of the Symmetric Group, preprint arXiv:1004.4248]. Also we describe a few combinatorial properties of some special elements in the associative quasi-classical Yang-Baxter algebra in a connection with the values of the ?-Grothendieck polynomials for some special permutations, and on the other hand, with the Ehrhart polynomial of the Chan-Robbins polytope.

  12. On Some Algebraic and Combinatorial Properties of Dunkl Elements

    NASA Astrophysics Data System (ADS)

    Kirillov, Anatol N.

    2013-06-01

    We introduce and study a certain class of nonhomogeneous quadratic algebras together with the special set of mutually commuting elements inside of each, the so-called Dunkl elements. We describe relations among the Dunkl elements. This result is a further generalization of similar results obtained in [S. Fomin and A. N. Kirillov, Quadratic algebras, Dunkl elements and Schubert calculus, in Advances in Geometry (eds. J.-S. Brylinski, V. Nistor, B. Tsygan and P. Xu), Progress in Math. Vol. 172 (Birkhäuser Boston, Boston, 1995), pp. 147-182, A. Postnikov, On a quantum version of Pieri's formula, in Advances in Geometry (eds. J.-S. Brylinski, R. Brylinski, V. Nistor, B. Tsygan and P. Xu), Progress in Math. Vol. 172 (Birkhäuser Boston, 1995), pp. 371-383 and A. N. Kirillov and T. Maenor, A Note on Quantum K-Theory of Flag Varieties, preprint]. As an application we describe explicitly the set of relations among the Gaudin elements in the group ring of the symmetric group, cf. [E. Mukhin, V. Tarasov and A. Varchenko, Bethe Subalgebras of the Group Algebra of the Symmetric Group, preprint arXiv:1004.4248]. Also we describe a few combinatorial properties of some special elements in the associative quasi-classical Yang-Baxter algebra in a connection with the values of the ?-Grothendieck polynomials for some special permutations, and on the other hand, with the Ehrhart polynomial of the Chan-Robbins polytope.

  13. Sulfonate groups grafted on Ti6Al4V favor MC3T3-E1 cell performance in serum free medium conditions.

    PubMed

    Felgueiras, Helena; Migonney, Véronique

    2014-06-01

    Ten years ago, we synthesized "bioactive model polymers" bearing sulfonate groups and proposed a mechanism of their modulation effect at different steps of the cell response. Then, we set up the grafting of polymers bearing sulfonate on Ti6Al4V surfaces by a grafting "from" technique making sure of the creation of covalent bonds between the grafted polymer and the Ti6Al4V surface. We have checked and confirmed the positive effect of grafted sulfonate groups on the osteoblastic cell response in vivo and in vitro but we did not elucidate the mechanism. The aim of this basic work consists first in investigating the role of sulfonate groups in the presence and in the absence of proteins at early stages of the osteointegration process on poly(sodium styrene sulfonate) poly(NaSS) grafted and ungrafted Ti6Al4V surfaces, in vitro. To understand the role of poly(NaSS) grafted chains on osteoblast-like cell response and to confirm/elucidate the importance of fetal bovine serum (FBS) proteins in the culture medium, MC3T3-E1 cells were seeded onto poly(NaSS) grafted and non-grafted Ti6Al4V surfaces. Cultures were carried out in a complete (10% FBS) and in a non-complete medium (without FBS). Cell viability assay, cell attachment number and cell adhesion strength were followed up to 3days of culture. The presence of proteins enhanced cell growth and development whatever the surface and the presence of sulfonate groups enhanced the cell attachment even in the absence of proteins, which suggests and confirms that the sulfonate groups can modify the activity of cells such as the secretion of binding proteins. Statistical differences were found in the attachment strength tests on poly(NaSS) grafted and ungrafted surfaces and showed that the sulfonate groups play an important role in the cell resistance to shear stress. PMID:24863216

  14. ICEG2D (v2.0) - An Integrated Software Package for Automated Prediction of Flow Fields for Single-Element Airfoils With Ice Accretion

    NASA Technical Reports Server (NTRS)

    Thompson David S.; Soni, Bharat K.

    2001-01-01

    An integrated geometry/grid/simulation software package, ICEG2D, is being developed to automate computational fluid dynamics (CFD) simulations for single- and multi-element airfoils with ice accretions. The current version, ICEG213 (v2.0), was designed to automatically perform four primary functions: (1) generate a grid-ready surface definition based on the geometrical characteristics of the iced airfoil surface, (2) generate high-quality structured and generalized grids starting from a defined surface definition, (3) generate the input and restart files needed to run the structured grid CFD solver NPARC or the generalized grid CFD solver HYBFL2D, and (4) using the flow solutions, generate solution-adaptive grids. ICEG2D (v2.0) can be operated in either a batch mode using a script file or in an interactive mode by entering directives from a command line within a Unix shell. This report summarizes activities completed in the first two years of a three-year research and development program to address automation issues related to CFD simulations for airfoils with ice accretions. As well as describing the technology employed in the software, this document serves as a users manual providing installation and operating instructions. An evaluation of the software is also presented.

  15. Differences in the Activities of Eight Enzymes from Ten Soil Fungi and Their Possible Influences on the Surface Structure, Functional Groups, and Element Composition of Soil Colloids

    PubMed Central

    Wang, Wenjie; Li, Yanhong; Wang, Huimei; Zu, Yuangang

    2014-01-01

    How soil fungi function in soil carbon and nutrient cycling is not well understood by using fungal enzymatic differences and their interactions with soil colloids. Eight extracellular enzymes, EEAs (chitinase, carboxymethyl cellulase, ?-glucosidase, protease, acid phosphatase, polyphenol oxidase, laccase, and guaiacol oxidase) secreted by ten fungi were compared, and then the fungi that showed low and high enzymatic activity were co-cultured with soil colloids for the purpose of finding fungi-soil interactions. Some fungi (Gomphidius rutilus, Russula integra, Pholiota adiposa, and Geastrum mammosum) secreted 3–4 enzymes with weak activities, while others (Cyathus striatus, Suillus granulate, Phallus impudicus, Collybia dryophila, Agaricus sylvicola, and Lactarius deliciosus) could secret over 5 enzymes with high activities. The differences in these fungi contributed to the alterations of functional groups (stretching bands of O-H, N-H, C-H, C?=?O, COO- decreased by 11–60%, while P?=?O, C-O stretching, O-H bending and Si-O-Si stretching increased 9–22%), surface appearance (disappearance of adhesive organic materials), and elemental compositions (11–49% decreases in C1s) in soil colloids. Moreover, more evident changes were generally in high enzymatic fungi (C. striatus) compared with low enzymatic fungi (G. rutilus). Our findings indicate that inter-fungi differences in EEA types and activities might be responsible for physical and chemical changes in soil colloids (the most active component of soil matrix), highlighting the important roles of soil fungi in soil nutrient cycling and functional maintenance. PMID:25398013

  16. Probabilistic neural networks applied to mineral potential mapping for platinum group elements in the Serra Leste region, Carajás Mineral Province, Brazil

    NASA Astrophysics Data System (ADS)

    Leite, Emilson Pereira; de Souza Filho, Carlos Roberto

    2009-03-01

    This work presents an application of probabilistic neural networks to map the potential for platinum group elements (PGE) mineralization sites in the northeast portion of the Carajás Mineral Province (CMP), Brazilian Amazon. Geological and geophysical gamma-spectrometric and magnetic data were used to generate evidential maps to derive input feature vectors. Feature vectors representing known mineralized locations were used as training data. The networks were created based on the training dataset and the evidential maps were classified in terms of probabilities using these networks. We have produced mineral potential models that depict classes with high, moderate and low favorability for Au-PGE mineralization sites and a model with high and low favorability classes for Cr-PGE mineralization sites. The cut-off values for each class were selected as the inflexion points of the curves of favorability against cumulative percentage of the study area. These curves were also used to check for the efficiency of the models by plotting the favorability values at the training sites. Leave-one-out tests were applied to validate the models and the overall accuracy is 87.5%. For Au-PGE mineralization sites, the high favorability areas accounts for 0.57% of the study area and are comprised mainly within meta-pelites and meta-siltites. For Cr-PGE mineralization sites, the high favorability areas are much more restrict and accounts for only 0.17% of the study area, being associated chiefly with mafic and ultramafic rocks. These mineral potential maps can be used as reconnaissance guides for future detailed ground surveys of possible new PGE occurrences, which is of critical importance to shorten exploration time and costs in such densely forested Amazonian terrains.

  17. Platinum-group elements in sewage sludge and incinerator ash in the United Kingdom: assessment of PGE sources and mobility in cities.

    PubMed

    Jackson, M T; Prichard, H M; Sampson, J

    2010-02-15

    Platinum-group element (PGE) concentrations in sewage sludge and incinerator ash compared with average PGE concentrations in road dust show a common pattern, characterized by a negative Rh anomaly. This similarity, found at 9 UK incinerators, suggests that there is a universal characteristic PGE pattern produced by common processes of dispersal of Pt, Pd and Rh derived from automobile catalytic converters. Ninety-one sewage sludge and incinerator ash samples from the sewage treatment facilities in Sheffield, Birmingham and 7 other UK cities were analyzed for PGE. The highest concentrations are 602ppb Pt and 710ppb Pd with lower maximum concentrations of 65ppb Rh, 100ppb Ru, 33ppb Ir and 12ppb Os. Ash from incinerated sewage was found to have higher PGE concentrations compared to the original sludge and the PGE ratios are preserved during incineration. Rh is more mobilized and dispersed than the other PGE as it is transported from roads into the drainage system and into sewage. Pt/Pd ratios of 1.0 in road dust and 0.9 in sewage and incinerator ash suggest that Pd is more mobile than Pt during dispersal. PGE abundances in stored incinerator ash of varying ages appear to have been affected by the variation in use of Pt, Pd and Rh in catalytic converters due to variation in their market prices. Concentrations of Os, Ir and Ru in ashes are greater in Sheffield and London than all the other city sites and may be derived from point industrial sources. PMID:19878972

  18. Direct determination of platinum group elements and their distributions in geological and environmental samples at the ng g(-1) level using LA-ICP-IDMS.

    PubMed

    Boulyga, Sergei F; Heumann, Klaus G

    2005-10-01

    Laser ablation inductively coupled plasma isotope dilution mass spectrometry (LA-ICP-IDMS) was applied to the direct and simultaneous determination of the platinum group elements (PGEs) Pt, Pd, Ru, and Ir in geological and environmental samples. A special laser ablation system with high ablation rates was used, along with sector field ICP-MS. Special attention was paid to deriving the distributions of PGEs in the pulverized samples. IDMS could not be applied to the (mono-isotopic) Rh, but the similar ablation behavior of Ru and Rh allowed Rh to be simultaneously determined via relative sensitivity coefficients. The laser ablation process produces hardly any oxide ions (which usually cause interference in PGE analysis with liquid sample injection), so the ICP-MS can be run in its low mass resolution but high-sensitivity mode. The detection limits obtained for the geological samples were 0.16 ng g(-1), 0.14 ng g(-1), 0.08 ng g(-1), 0.01 ng g(-1) and 0.06 ng g(-1) for Ru, Rh, Pd, Ir and Pt, respectively. LA-ICP-IDMS was applied to different geological reference materials (TDB-1, WGB-1, UMT-1, WMG-1, SARM-7) and the road dust reference material BCR-723, which are only certified for some of the PGEs. Comparisons with certified values as well as with indicative values from the literature demonstrated the validity of the LA-ICP-IDMS method. The PGE concentrations in subsamples of the road dust reference material correspond to a normal distribution, whereas the distributions in the geological reference materials TDB-1, WGB-1, UMT-1, WMG-1, and SARM-7 are more complex. For example, in the case of Ru, a logarithmic normal distribution best fits the analyzed concentrations in TDB-1 subsamples, whereas a pronounced nugget effect was found for Pt in most geological samples. PMID:16132139

  19. 47 CFR 13.203 - Examination elements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...techniques. Questions concerning specialized theory and practice applicable to the proper... (1) Telegraphy Element 1: 16 code groups per minute. (2) Telegraphy Element... (3) Telegraphy Element 3: 20 code groups per minute. (4) Telegraphy...

  20. 47 CFR 13.203 - Examination elements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...techniques. Questions concerning specialized theory and practice applicable to the proper... (1) Telegraphy Element 1: 16 code groups per minute. (2) Telegraphy Element... (3) Telegraphy Element 3: 20 code groups per minute. (4) Telegraphy...

  1. 47 CFR 13.203 - Examination elements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...techniques. Questions concerning specialized theory and practice applicable to the proper... (1) Telegraphy Element 1: 16 code groups per minute. (2) Telegraphy Element... (3) Telegraphy Element 3: 20 code groups per minute. (4) Telegraphy...

  2. CRITICAL ELEMENTS FOR CERTIFICATION

    EPA Science Inventory

    The Microbiology Subcommittee of the Drinking Water Laboratory Certification Implementation Work Group has revised Chapter V of the Manual for the Interim Certification of Laboratories Involved in Analyzing Public Drinking Water Supplies. The technical criteria for Chapter V are ...

  3. Platinum-group elements (PGE) and Rhenium in Marine Sediments across the Cretaceous-Tertiary Boundary: Constraints on Re-PGE Transport in the Marine Environment

    NASA Technical Reports Server (NTRS)

    Lee, Cin-Ty Aeolus; Wasserburg, Gerald J.; Kyte, Frank T.

    2003-01-01

    The nature of Re-platinum-group element (PGE; Pt, Pd, Ir, Os, Ru) transport in the marine environment was investigated by means of marine sediments at and across the Cretaceous-Tertiary boundary (KTB) at two hemipelagic sites in Europe and two pelagic sites in the North and South Pacific. A traverse across the KTB in the South Pacific pelagic clay core found elevated levels of Re, Pt, Ir, Os, and Ru, each of which is approximately symmetrically distributed over a distance of approx. 1.8 m across the KTB. The Re-PGE abundance patterns are fractionated from chondritic relative abundances: Ru, Pt, Pd, and Re contents are slightly subchondritic relative to Ir, and Os is depleted by approx. 95% relative to chondritic Ir proportions. A similar depletion in Os (approx. 90%) was found in a sample of the pelagic KTB in the North Pacific, but it is enriched in Ru, Pt, Pd, and Re relative to Ir. The two hemipelagic KTB clays have near-chondritic abundance patterns. The approx. 1.8-m-wide Re-PGE peak in the pelagic South Pacific section cannot be reconciled with the fallout of a single impactor, indicating that postdepositional redistribution has occurred. The elemental profiles appear to fit diffusion profiles, although bioturbation could have also played a role. If diffusion had occurred over approx. 65 Ma, the effective diffusivities are approx. 10(exp -13)sq cm/s, much smaller than that of soluble cations in pore waters (approx. 10(exp -5) sq cm/s). The coupling of Re and the PGEs during redistribution indicates that postdepositional processes did not significantly fractionate their relative abundances. If redistribution was caused by diffusion, then the effective diffusivities are the same. Fractionation of Os from Ir during the KTB interval must therefore have occurred during aqueous transport in the marine environment. Distinctly subchondritic Os/Ir ratios throughout the Cenozoic in the South Pacific core further suggest that fractionation of Os from Ir in the marine environment is a general process throughout geologic time because most of the inputs of Os and Ir into the ocean have OsAr ratios greater than or = 1. Mass balance calculations show that Os and Re burial fluxes in pelagic sediments account for only a small fraction of the riverine Os (less than 10%) and Re (less than 0.1%) inputs into the oceans. In contrast, burial of Ir in pelagic sediments is similar to the riverine Ir input, indicating that pelagic sediments are a much larger repository for Ir than for Os and Re. If all of the missing Os and Re is assumed to reside in anoxic sediments in oceanic margins, the calculated burial fluxes in anoxic sediments are similar to observed burial fluxes. However, putting all of the missing Os and Re into estuarine sediments would require high concentrations to balance the riverine input and would also fail to explain the depletion of Os at pelagic KTB sites, where at most approx. 25% of the K-T impactor's Os could have passed through estuaries. If Os is preferentially sequestered in anoxic marine environments, it follows that the OsAr ratio of pelagic sediments should be sensitive to changes in the rates of anoxic sediment deposition. There is thus a clear fractionation of Os and Re from Ir in precipitation out of sea water in pelagic sections. Accordingly, it is inferred here that Re and Os are removed from sea water in anoxic marine depositional regimes.

  4. GEANT4 Simulation of Hadronic Interactions at 8-GeV/C to 10-GeV/C: Response to the HARP-CDP Group

    SciTech Connect

    Uzhinsky, V.; /Dubna, JINR /CERN; Apostolakis, J.; Folger, G.; /CERN; Ivanchenko, V.N.; /CERN /Moscow State U.; Kossov, M.V.; /CERN /Moscow, ITEP; Wright, D.H.; /SLAC

    2011-11-21

    The results of the HARP-CDP group on the comparison of GEANT4 Monte Carlo predictions versus experimental data are discussed. It is shown that the problems observed by the group are caused by an incorrect implementation of old features at the programming level, and by a lack of the nucleon Fermi motion in the simulation of quasielastic scattering. These drawbacks are not due to the physical models used. They do not manifest themselves in the most important applications of the GEANT4 toolkit.

  5. arXiv:math.GT/0703594v120Mar2007 Virtual Knot Invariants from Group Biquandles and Their Cocycles

    E-print Network

    Silver, Dan

    of South Alabama March 20, 2007 Abstract A group-theoretical method, via Wada's representations using Wada's braid group representations. Cocycle invariants for these biquandles are studied generalizations of the Burau representation. The principal examples that we consider in this paper come from Wada

  6. A simple molecular-orbital theory of the nonlinear optical properties of group III-V and II-VI compounds

    Microsoft Academic Search

    CHUNG L. TANG

    1973-01-01

    The second-order nonlinear optical susceptibility in the low-frequency limit for Group III-V and II-VI semiconductors can be understood in terms of a very simple and yet surprisingly accurate molecular-orbital model of the tetrahedral bonds of the crystal. The physical origin of the nonlinearity is the field-dependence in the ionicity of the bond due to the transfer of valence charge from

  7. Controlled group V intermixing in InGaAsP quantum well structures and its application to the fabrication of two section tunable lasers

    NASA Astrophysics Data System (ADS)

    Teng, J. H.; Dong, J. R.; Chua, S. J.; Lai, M. Y.; Foo, B. C.; Thompson, D. A.; Robinson, B. J.; Lee, A. S. W.; Hazell, John; Sproule, Irwin

    2002-10-01

    We report the technique of controlled group V quantum well intermixing (QWI) in a compressively strained In0.76Ga0.24As0.85P0.15/In0.76Ga0.24As0.52P0.48 multiquantum well laser structure and its application to the fabrication of two-section tunable lasers. The blueshift of the band-gap energy was enhanced by capping the samples with films of SiO2 or low-temperature grown InP, while suppressed by a SixNy film with a refractive index of about 2.1. Spatially selective band-gap tuning was achieved by patterning the dielectric film into dot and strip arrays with different surface coverage. Time-of-flight secondary ion mass spectra showed that the enhanced blueshift was caused by the interdiffusion of group V atoms between the quantum wells and barriers. A group V interstitial interdiffusion mechanism is proposed for the sample capped with SiO2 and this is supported by the even more efficient intermixing induced by low-temperature InP, which contains a high concentration of excess phosphorus. A two-section tunable laser operating around 1.55 ?m was fabricated using this QWI technology. A tuning range of about 10 nm was demonstrated by simply changing the current injected into the phase tuning section.

  8. Platinum Group Elements, 187OS/188OS and 87SR/86SR Isotope Systematics in Depleted Fluid-Modified Mariana Fore-Arc Peridotites

    NASA Astrophysics Data System (ADS)

    Harvey, J.; Savov, I. P.; Shirey, S. B.; Horan, M. F.; Mock, T. D.

    2012-12-01

    The serpentine mud volcanoes of the Izu-Bonin-Mariana (IBM) fore-arc, collected during Ocean Drilling Program Leg 195 [1], contain hard-rock clasts of serpentine sampled from close to the décollement, which separates the down-going Pacific slab from the overlying mantle wedge. These clasts preserve evidence for melt depletion (>25 % melt extraction in many instances) in a sub-arc environment, and extensive (40 - 100%) serpentinization due to subsequent fluid / peridotite interaction, e.g. [2]. Platinum-group element (PGE) abundances are not consistent with melt-depletion alone [3]. Fractionation between I-PGE (Os, Ir, Ru) has resulted in groups of IBM serpentinites with either a high chondrite-normalized Os/Ir ratio (OsN/IrN) or a low OsN/IrN ratio. Similarly, fractionation of P-PGE (Pt, Pd) is marked, and distinguishes the IBM serpentinites from worldwide abyssal peridotites. Interaction with high-pH fluids [4] may have partially oxidized mantle sulphide, the major primary host for PGE in these rocks, leading to partial breakdown to sulphate and the selective redistribution of certain PGE (Os, Ru, Pt), a feature normally associated with sub-aerial weathering [5], but which likely prevails in other oxidizing environments. In particular, the Re-Os systematics of the high (OsN/IrN) IBM serpentinites have been disturbed by the addition of Os. Unlike peridotite xenoliths associated with magmatic regions of subduction zones where subduction-related Os-addition is unequivocally radiogenic and derived from crustal material [6][7], where Os has been added to the IBM serpentinites it is unradiogenic and was most likely derived from within the oceanic mantle. IBM serpentinites therefore preserve osmium isotope ratios that are exclusively sub-chondritic (187Os/188Os ? 0.127), as previously reported [8]. These serpentinized peridotites were produced by at least a three-step process: melt depletion, serpentinization, and the mobilization of Os, Ru and Pt to produce low OsN/IrN "donor" and high OsN/IrN "recipient" serpentinites. The distinct chondrite normalized PGE patterns of the low OsN/IrN serpentinites are remarkably similar to those of back-arc basin basalts (BABB) from sites 291, 292, 444A, 450 drilled in the Philippine Sea Plate (PSP) during DSDP Legs 31, 58 and 59 [9]. [1] Fryer, et al. (1992) Proc. ODP Sci. Results 125, Fryer, P., Pearce, J. A., Stokking, L. B., et al., 373-385, Ocean Drilling Program, College Station TX, USA. [2] Savov et al. (2005) Geochem. Geophys. Geosyst. 6, Q04J15, doi:10.1029/2004GC000777 [3] Handler, & Bennett (1999) Geochim. Cosmochim. Acta 63, 3597-3618 [4] Mottl, M.J. (1992) Proc. ODP Sci. Results, 125, Fryer, P., Pearce, J. A., Stokking, L. B., et al., 373-385, Ocean Drilling Program, College Station TX, USA. [5] Lorand, et al. (2003) Geochim. Cosmochim. Acta 67, 4137-4151. [6] Brandon et al. (1999) Chem. Geol. 160, 387-407. [7] Widom et al. (2003) Chem. Geol. 196, 283- 306. [8] Parkinson et al. (1999) Science 281, 211-312 [9] Dale et al. (2008) Chem. Geol. 248, 213-238.

  9. Optical Modeling of a Holographic Single Element Head-mounted Display Y. Ha, V. Smirnov, L. Glebov, and J.P. Rolland

    E-print Network

    Glebov, Leon

    proposed, a single holographic element head-mounted display (HMD) was modeled. Results show that a single in HMD design, but mainly as optical combiners.[3] Volume holographic elements are thick phase gratings, and in section 3 an example of a design of a holographic single element eyepiece for HMD based on such method

  10. Prevalence of Group B Streptococcus serotypes III and V in pregnant women of Rio de Janeiro, Brazil

    PubMed Central

    Soares, Georgia Cristina Tavolaro; Alviano, Daniela Sales; da Silva Santos, Gabriela; Alviano, Celuta Sales; Mattos-Guaraldi, Ana Luiza; Nagao, Prescilla Emy

    2013-01-01

    GBS serotypes III and V were the most prevalent in pregnant women and exhibited resistance to tetracycline, clindamycin and sulfamethoxazole/trimethoprim. Serotype III showed high sialic acid content and PFGE analysis discerned 33 heterogeneous profiles. Phenotypic and genotypic characterization could be relevant to control GBS infections unaffected by intra-partum chemoprophylaxis. PMID:24516454

  11. Critical issues in III-V compound semiconductor epitaxy on group IV (silicon, germanium) substrates for optoelectronic applications

    Microsoft Academic Search

    Robert Michael Sieg

    1998-01-01

    Controlled heteroepitaxy of GaAs onto Ge surfaces is an important enabling technology for high efficiency multi-junction III-V solar cells grown on Ge wafers for space satellite power applications, and is also a critical step in the proposed integration of GaAs devices with Si microelectronics via dislocation-suppressing graded SisbxGesb1-x buffer layers. The close lattice and thermal match between GaAs and Ge

  12. Genetic Programming in Europe Report of the E v o G P Working Group on Genetic Programming of

    E-print Network

    Fernandez, Thomas

    of techniques which allow the automatic production of computer programs. As a field GP was founded by John Koza computer programs rather than inflexible fixed­length vectors of parameters. In GP programs are typically group. We indicate the likely benefits of this technology now and in the near future and we make

  13. Group V Phospholipase A2-mediated Oleic Acid Mobilization in Lipopolysaccharide-stimulated P388D1 Macrophages*

    E-print Network

    Dennis, Edward A.

    recently shown that arachidonic acid (AA)1 mobilization and prostaglandin production stimulated by platelet fundamentally plays a regulatory role, whereas the sPLA2 plays an augmentative role by providing most of the AA). Nevertheless, group IIA sPLA2 appears to serve in the same augmentative role (9, 10, 16, 17). Recently

  14. Elemental diffusion during the droplet epitaxy growth of In(Ga)As/GaAs(001) quantum dots by metal-organic chemical vapor deposition

    SciTech Connect

    Chen, Z. B.; Chen, B.; Wang, Y. B.; Liao, X. Z., E-mail: xiaozhou.liao@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Lei, W. [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, WA 6009 (Australia); Tan, H. H.; Jagadish, C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Zou, J. [Materials Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD 4072 (Australia); Ringer, S. P. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia)

    2014-01-13

    Droplet epitaxy is an important method to produce epitaxial semiconductor quantum dots (QDs). Droplet epitaxy of III-V QDs comprises group III elemental droplet deposition and the droplet crystallization through the introduction of group V elements. Here, we report that, in the droplet epitaxy of InAs/GaAs(001) QDs using metal-organic chemical vapor deposition, significant elemental diffusion from the substrate to In droplets occurs, resulting in the formation of In(Ga)As crystals, before As flux is provided. The supply of As flux suppresses the further elemental diffusion from the substrate and promotes surface migration, leading to large island formation with a low island density.

  15. Elemental Abundance Analyses with DAO Spectrograms. XXXVIII. The SB2 Stars HR 104 (A2 V) and ? Aql (B9.5 III)

    NASA Astrophysics Data System (ADS)

    Adelman, Saul J.; Yüce, Kutluay; Gulliver, Austin F.

    2015-06-01

    The study of the elemental abundances of double-lined spectroscopic binaries should provide information on the chemical differentiation of a once uniform prestellar nebula. To determine the effective temperatures and surface gravities of the primary and secondary stellar components of HR 104 and ? Aql, we used parameters derived from their orbital analyses and the requirement of equal abundances derived from Fe I and Fe II lines. For constraints we had optical region spectrophotometry for ? Aql and the large equivalent width ratios for the many spectral metal lines which were produced in both stellar atmospheres for HR 104. Since the primary stars were much brighter than the secondary stars, the abundances are considerably better determined for the primary stars. For HR 104 A we found Teff = 9875 K, log g = 4.26, and ? = 1.7 km s-1; for HR 104 B Teff = 7200 K, log g = 4.26, and ? = 0.6 km s-1; for ? Aql A Teff = 10400 K, log = 3.63, and ? = 0.3 km s-1; and for ? Aql B Teff = 10250 K, log = 4.20, and ? = 1.9 km s-1. The abundances of HR 104 A, HR 104 B, and ? Aql A are best described as the solar pattern. Those of ? Aql B suggest a weak nonmagnetic CP star pattern. While there is no trace of the Hg II 3984 line for ? Aql, the most extreme observed abundance anomalies for the secondary are those of Ca, V, Mn, and Ni. Further study of this hot marginal Am star could provide insights into the origin of the nonsolar chemical abundances.

  16. An efficient code for calculation of the 6C, 9C and 12C symbols for C3v, T, and O point groups

    NASA Astrophysics Data System (ADS)

    Nikitin, A. V.

    2012-03-01

    A new code designed to calculate the 6 C, 9 C, and 12 C symbols for C3v, T, and O point groups is presented. The program is based on an algorithm that uses the symmetry property between pair and impair representations. This algorithm allows one to speed up the C-symbols calculation and increase the efficiency of spectroscopic programs based on the irreducible tensorial formalism. Program summaryProgram title: 6912C Catalogue identifier: AEKZ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKZ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1214 No. of bytes in distributed program, including test data, etc.: 22 097 Distribution format: tar.gz Programming language: C++ Computer: Any computer with C, C++ compiler Operating system: Linux SUSE, Windows XP64 RAM: 400 Kb Classification: 4.2, 16.2, 16.3 Nature of problem: Spectroscopy of symmetric atmospheric molecules. Solution method: The program is based on an algorithm that uses the symmetry property between pair and impair representations. Running time: The test program provided takes a few seconds for C3v, a few minutes for T and a few days for O.

  17. Whitehead Groups of Spinor Groups

    NASA Astrophysics Data System (ADS)

    Monastyrny?, A. P.; Yanchevski?, V. I.

    1991-02-01

    The Whitehead groups of spinor groups are studied. The known Kneser-Tits conjecture for spinor groups is reduced to a spinor analogue of the Tannaka-Artin problem, namely, to the question of whether the group K1Spin(D), where D is a division ring of exponent 2 , is trivial. A counterexample to the Kneser-Tits problem is constructed in the class of spinor groups. The group K1Spin(D) is computed. The stability of the Whitehead groups of spinor groups under purely transcendental extensions of the ground field is established. The R-equivalence on the k-points of spinor groups and the weak approximation problem are considered. The study of spinor group completes the study of the Whitehead groups of algebraic groups of classical type, that was started in studying reduced K-theory (V.P. Platonov) and was continued for reduced unitary K-theory (V.I. Yanchevski?) and Hermitian K-theory (Platonov and Yanchevski?). Bibliography: 50 titles.

  18. Batisivite, V8Ti6[Ba(Si2O)]O28, a new mineral species from the derbylite group

    NASA Astrophysics Data System (ADS)

    Reznitsky, L. Z.; Sklyarov, E. V.; Armbruster, T.; Galuskin, E. V.; Ushchapovskaya, Z. F.; Polekhovsky, Yu. S.; Karmanov, N. S.; Kashaev, A. A.; Barash, I. G.

    2008-12-01

    Batisivite has been found as an accessory mineral in the Cr-V-bearing quartz-diopside metamorphic rocks of the Slyudyanka Complex in the southern Baikal region, Russia. A new mineral was named after the major cations in its ideal formula (Ba, Ti, Si, V). Associated minerals are quartz, Cr-V-bearing diopside and tremolite; calcite; schreyerite; berdesinskiite; ankangite; V-bearing titanite; minerals of the chromite-coulsonite, eskolaite-karelianite, dravite-vanadiumdravite, and chernykhite-roscoelite series; uraninite; Cr-bearing goldmanite; albite; barite; zircon; and unnamed U-Ti-V-Cr phases. Batisivite occurs as anhedral grains up to 0.15-0.20 mm in size, without visible cleavage and parting. The new mineral is brittle, with conchoidal fracture. Observed by the naked eye, the mineral is black and opaque, with a black streak and resinous luster. Batisivite is white in reflected light. The microhardness (VHN) is 1220-1470 kg/mm2 (load is 30 g), the mean value is 1330 kg/mm2. The Mohs hardness is near 7. The calculated density is 4.62 g/cm3. The new mineral is weakly anisotropic and bireflected. The measured values of reflectance are as follows (?, nm— R {max/'}/ R {min/'}): 440—17.5/17.0; 460—17.3/16.7; 480—17.1/16.5; 500—17.2/16.6; 520—17.3/16.7; 540—17.4/16.8; 560—17.5/16.8; 580—17.6/16.9; 600—17.7/17.1; 620—17.7/17.1; 640—17.8/17.1; 660—17.9/17.2; 680—18.0/17.3; 700—18.1/17.4. Batisivite is triclinic, space group P overline 1 ; the unit-cell dimensions are: a = 7.521(1) Å, b = 7.643(1) Å, c = 9.572(1) Å, ? = 110.20°(1), ? = 103.34°(1), ? = 98.28°(1), V = 487.14(7) Å3, Z = 1. The strongest reflections in the X-ray powder diffraction pattern [ d, Å ( I, %)( hkl)] are: 3.09(8)(12 overline 2 ); 2.84, 2.85(10)(021, 120); 2.64(8)(21 overline 3 ); 2.12(8)(31 overline 3 ); 1.785(8)(32 overline 4 ), 1.581(10)(24 overline 2 ); 1.432, 1.433(10)(322, 124). The chemical composition (electron microprobe, average of 237 point analyses, wt %) is: 0.26 Nb2O5, 6.16 SiO2, 31.76 TiO2, 1.81 Al2O3, 8.20 VO2, 26.27 V2O3, 12.29 Cr2O3, 1.48 Fe2O3, 0.08 MgO, 11.42 BaO; the total is 99.73. The VO2/V2O3 ratio has been calculated. The simplified empirical formula is (V{4.8/3+}Cr2.2V{0.7/4+}Fe0.3)8.0(Ti5.4V{0.6/4+})6.0[Ba(Si1.4Al0.5O0.9)]O28. An alternative to the title formula could be a variety (with the diorthogroup Si2O7) V8Ti6[Ba(Si2O7)]O22. Batisivite probably pertains to the V{8/3+}Ti{6/4+}[Ba(Si2O)]O28-Cr{8/3+}Ti{6/4+} [Ba(Si2O)]O28 solid solution series. The type material of batisivite has been deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  19. Endothelial protein C receptor-associated invasiveness of rheumatoid synovial fibroblasts is likely driven by group V secretory phospholipase A2

    PubMed Central

    2014-01-01

    Introduction Rheumatoid synovial fibroblasts (RASFs) mediate joint inflammation and destruction in rheumatoid arthritis (RA). Endothelial protein C receptor (EPCR) is a specific receptor for the natural anticoagulant activated protein C (APC). It mediates the cytoprotective properties of APC and is expressed in rheumatoid synovial tissue. A recent report shows that group V secretory phospholipase A2 (sPLA2V) prevents APC from binding to EPCR in endothelium and inhibits EPCR/APC function. The aim of this study was to investigate the expression and function of EPCR on RASFs. Methods Human synovial fibroblasts (SFs) were isolated from RA or osteoarthritis (OA) synovial tissues and treated with control, EPCR, or sPLA2V small interfering RNA (siRNA); recombinant human APC, tumor necrosis factor-alpha (TNF-?), or sPLA2V. RASF viability and migration/invasion were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and collagen gel migration/invasion assays, respectively, and cartilage degradation by 1,9-dimethylmethylene blue (DMMB) assay in the presence of human OA articular cartilage explants. The expression or activation of cytokines, EPCR, cadherin-11, mitogen-activated protein (MAP) kinases, and nuclear factor-kappa-B (NF-?B) or both were detected by enzyme-linked immunosorbent assay, Western blotting, or immunostaining. Results EPCR was expressed by both OASFs and RASFs but was markedly increased in RASFs. When EPCR was suppressed by siRNA or blocking antibody cell viability, cell invasion and cartilage degradation were reduced by more than 30%. Inflammatory mediators interleukin-1-beta (IL-1?), cadherin-11, and NF-?B were significantly reduced by EPCR suppression under control or TNF-?-stimulated conditions. The expression or activation (or both) of MAP kinases ERK, p38, and JNK were also markedly decreased in cells transfected with EPCR siRNA. Further analysis revealed that sPLA2V co-localized with EPCR on RASFs. Suppression of sPLA2V reduced cell viability and cartilage degradation and increased APC binding to RASFs. Conversely, recombinant sPLA2V increased cartilage degradation, blocked APC binding to RASFs, and could not rescue the effects induced by EPCR suppression. Conclusions Our results demonstrate that EPCR is overexpressed by RASFs and mediates the aggressive behavior of RASFs. This function of EPCR is contrary to its cytoprotective role in other settings and is likely driven by sPLA2V. PMID:24495480

  20. American Elements

    NSDL National Science Digital Library

    2006-02-27

    This company's web site features an interactive periodic chart that provides information on the elements, including a description, physical and thermal properties, abundance, isotopes, ionization energy, the element's discoverer, translations of element names into several languages, and bibliographic information on research-and-development publications involving the element. Additional information includes technical information and information on manufactured products for elemental metals, metallic compounds, and ceramic and crystalline products. The American Elements company manufactures engineered and advanced material products.

  1. A new mixed group 5 metal selenide, Nb1.41V0.59Se9

    PubMed Central

    Lee, Eunsil; Yun, Hoseop

    2011-01-01

    The new mixed-metallic phase, niobium vanadium nona­selenide, (Nb2-xVx)Se9 (0.18? x ? 0.59) is isostructural with monoclinic V2Se9. The structure is composed of chains of bicapped trigonal–prismatic [MSe8] units. The metal (M) site is occupied by statistically disordered Nb [0.706?(5)] and V [0.294?(5)] atoms. Two trigonal prisms are linked by sharing a recta­ngular face composed of two Se2 2? pairs. Through three edging and capping Se atoms, the chains are extended along [101]. The chain shows alternating short [2.8847?(7)?Å] and long [3.7159?(7)?Å] M—M distances. The structure shows a wide range of Se—Se inter­actions. In addition to the Se2 2? pairs of the recta­ngular face, an inter­mediate Se?Se separation [2.6584?(5)?Å] is found. The amount of each metal can vary, [(Nb2-xVx)Se9, 0.18 ? x ?m 0.59] and they seem to form a random substitutional solid solution. The M—M distances increase gradually by increasing the amount of Nb atoms. The classical charge-balance of the compound can be described as [M 4+]2[Se2 2?]2[Se5 4?]. PMID:22064790

  2. Dielectric, elastic and piezoelectric properties of RCa 4O(BO 3) 3 ( R=rare-earth elements) crystals with monoclinic structure of point group m

    Microsoft Academic Search

    Hiroyuki Shimizu; Takashi Nishida; Hiroaki Takeda; Tadashi Shiosaki

    2009-01-01

    Rare-earth calcium oxoborate RCa4O(BO3)3 (R=La, Gd, Y) piezoelectric single crystals were successfully grown by a conventional RF-heating Czochralski (Cz) technique. They belong to the monoclinic system with point group m, and have 27 independent material constants. We developed the determination scheme (cuts and vibration modes) of the material constants in point group m. Their material constants were evaluated on the

  3. The refractive group.

    PubMed

    Campbell, C

    1997-06-01

    Spherocylindrical optical elements can be decomposed into a sphere-equivalent component and two cross-cylinder components, oriented at 45 degrees to one another. These components in turn can be represented with a simple matrix formalism. This matrix formalism allows it to be seen that the components also form members of an eight element group, designated the refractive group. The structure of this group is developed including its algebra and its representation with Cayley diagrams. The group is identified as the eight element dihedral group, D4, and is compared to another well-known eight element group, the quaternion group. An example is given using the group formal algebra to develop the transfer equations for spherocylindrical wavefronts. Certain properties of propagating spherocylindrical wavefronts, such as nonrotation of cylinder axes, are seen to come directly as consequences of the group properties. PMID:9255816

  4. Measurement of the resonance structure parameters of the total cross sections of some elements in the neutron energy range 0.3–2.7 MeV

    Microsoft Academic Search

    M. N. Nikolaev; V. V. Filippov

    1963-01-01

    A way of representing cross-sectional structure data, suitable for practical calculations, is proposed and the data for 11 elements, obtained by analysis of the transmission curves, are given in this form. It is shown that for elements of medium atomic weight (up to niobium) and lead and bismuth, the cross sections had a resonance structure in the whole of the

  5. Mobilisation of trace elements from as-supplied and additionally cleaned coal: Predictions for Ba, Be, Cd, Co, Mo, Nb, Sb, V and W

    Microsoft Academic Search

    B. M. Gibbs; D. Thompson; B. B. Argent

    2008-01-01

    The partitioning of the elements antimony, barium, beryllium, cadmium, cobalt, molybdenum and vanadium between the products of combustion of coals containing them burnt as pulverised fuel in excess air has been modelled using the MTDATA thermodynamic equilibrium package with data from the MTOX silicate melt model added to the standard database and trace element data added where necessary. The coals

  6. Helium production by 9.85MeV neutrons in elemental iron, nickel, and copper and in ⁵⁶Fe and {sup 58,60,61}Ni

    Microsoft Academic Search

    R. C. Haight; D. W. Kneff; B. M. Oliver; L. R. Greenwood; H. Vonach

    1996-01-01

    Neutron-induced helium production, which can contribute substantially to radiation damage, is an important parameter in the choice of structural materials and other component materials for both fusion and fission reactors. Here, helium production cross sections for the elements iron, nickel, and copper and for the isotopes ⁵⁶Fe, ⁵⁸Ni, ⁶°Ni, and ⁶¹Ni for 9.85-MeV neutrons have been measured by irradiation with

  7. Implication of TLR- but Not of NOD2-Signaling Pathways in Dendritic Cell Activation by Group B Streptococcus Serotypes III and V

    PubMed Central

    Lemire, Paul; Roy, David; Fittipaldi, Nahuel; Okura, Masatoshi; Takamatsu, Daisuke; Bergman, Eugenia; Segura, Mariela

    2014-01-01

    Group B Streptococcus (GBS) is an important agent of life-threatening invasive infection. It has been previously shown that encapsulated type III GBS is easily internalized by dendritic cells (DCs), and that this internalization had an impact on cytokine production. The receptors underlying these processes are poorly characterized. Knowledge on the mechanisms used by type V GBS to activate DCs is minimal. In this work, we investigated the role of Toll-like receptor (TLR)/MyD88 signaling pathway, the particular involvement of TLR2, and that of the intracellular sensing receptor NOD2 in the activation of DCs by types III and V GBS. The role of capsular polysaccharide (CPS, one of the most important GBS virulence factors) in bacterial-DC interactions was evaluated using non-encapsulated mutants. Despite differences in the role of CPS between types III and V GBS in bacterial internalization and intracellular survival, no major differences were observed in their capacity to modulate release of cytokines by DC. For both serotypes, CPS had a minor role in this response. Production of cytokines by DCs was shown to strongly rely on MyD88-dependent signaling pathways, suggesting that DCs recognize GBS and become activated mostly through TLR signaling. Yet, GBS-infected TLR2-/- DCs only showed a partial reduction in the production of IL-6 and CXCL1 compared to control DCs. Surprisingly, CXCL10 release by type III or type V GBS-infected DCs was MyD88-independent. No differences in DC activation were observed between NOD2-/- and control DCs. These results demonstrate the involvement of various receptors and the complexity of the cytokine production pathways activated by GBS upon DC infection. PMID:25436906

  8. Irradiation and examinations of the second group of thermionic fuel element insulators (UCA-2). [YO; AlO; YAlO

    SciTech Connect

    Lawrence, L.A.; Ard, K.E. (Westinghouse Hanford Company, P.O. Box 1970, Mail Stop L5-02, Richland, WA (USA)); Veca, A.R.; Giraldez, E.M. (General Atomics, P.O. Box 58608, San Diego, CA (USA))

    1991-01-05

    Thermionic fuel element sheaths, seal and intercell insulators, and end restraints were irradiated in a fast neutron spectrum and examined. Samples were irradiated at temperatures ranging from 1110 K to 1200 K to fast fluences from 3.4{times}10{sup 22} n/cm{sup 2} to 6.0{times}10{sup 22} n/cm{sup 2}. Sample examinations included visual, photographic, dimensional, electrical resistance to temperatures of 1175 K, helium leak rates, and metallography. Examinations of the end restraints and intercell insulators, which were limited to visual and photographic examination, showed no adverse effects from the irradiation. Alumina and yttria have been identified as insulator materials which meet design requirements.

  9. Group separation of transplutonium and rare-earth elements by liquid chromatography with a free stationary phase using 2,4,6-Tris[ditolylphosphoryl]-1,3,5-triazine

    SciTech Connect

    Chmutova, M.K.; Ivanova, L.A.; Bodrin, G.B. [V.I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Moscow (Russian Federation)] [and others

    1995-03-01

    Methods are developed for group separation of trace quantities of transplutonium (TPE) and weighable amounts of rare-earth elements (REE) by liquid chromatography with a free stationary phase in systems based on bifunctional neutral organophosphorus compounds. Using a stationary phase of 2,4,6-tris(ditolylphosphoryl)-1,3,5-triazine in CHCl{sub 3}, REE are first eluted by 0.5 M NH{sub 4}SCN-1 M HCl and then TPE by 0.025 M hydroxyethylidenediphosphonic acid in H{sub 2}O. The fractions contained {approximately} 100% of one of the groups without an impurity of the other. Use of the same eluents and a CHCl{sub 3} solution of tetraphenyl-methylenediphosphine dioxide as the stationary phase gave 95.4% pure REE and 97.5% pure TPE.

  10. Rare Earth Elements in Soils

    Microsoft Academic Search

    Zhengyi Hu; Silvia Haneklaus; Gerd Sparovek; Ewald Schnug

    2006-01-01

    Rare earth elements (REEs) comprise a group of 17 elements with very similar chemical and physical properties, which include scandium (Sc, Z=21), yttrium (Y, Z=39), and the lanthanides with successive atomic numbers (Z from 57 to 71). Lanthanides are the elements lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium

  11. Resonating-group study of the /sup 3/He(/sup 3/H)+. cap alpha. systems: Bound states to 113 MeV

    SciTech Connect

    Furber, R.D.; Brown, R.E.; Peterson, G.L.; Thompson, D.R.; Tang, Y.C.

    1982-01-01

    An effective nucleon-nucleon spin-orbit force is included in a single-channel resonating-group calculation for the /sup 3/He(/sup 3/H)+..cap alpha.. system up to a c.m. energy of 113.1 MeV. The parameters of the spin-orbit force were chosen to reproduce the phase shifts for p+..cap alpha.. scattering at low energies and the bound-state properties of /sup 7/Li and /sup 7/Be. A phenomenological, parity-dependent imaginary potential is used to account for reaction channels. The calculation gives a reasonable account of the experimental differential cross sections and analyzing power available in this energy region.

  12. Identification of cis- and trans-acting elements in pHW126, a representative of a novel group of rolling circle plasmids.

    PubMed

    Rozhon, Wilfried; Khan, Mamoona; Petutschnig, Elena; Poppenberger, Brigitte

    2011-01-01

    pHW126, pIGRK, pIGMS31 and pRAO1 are the only known members of a novel and as yet uncharacterised family of rolling circle plasmids. pHW126 contains only two open reading frames, of which one shows homology to pMV158-family mobilisation proteins. Here we provide evidence that the second open reading frame encodes a replication protein (Rep). Mutation or deletion of this gene resulted in replication deficient constructs, but providing functional Rep from a compatible vector rescued these constructs, indicating that Rep acts in trans. An approximately 300 bp cis-acting region representing the origin of replication was identified upstream of the rep gene. The origin was identified to be composed of three parts: an accessory region, a conserved stretch and four perfect tandem repeats. The two latter elements were essential for replication. Constructs with a deletion of the accessory region could still replicate, but their loss rate was high, indicating that the accessory region is necessary for plasmid maintenance under non-selective conditions. Interestingly, pHW126 could replicate in all Enterobacteriaceae tested while Agrobacterium tumefaciens and Pseudomonas syringae were inappropriate hosts. Thus, pHW126 seems to have a rather limited host range. PMID:20854841

  13. Ring-laser gyroscope system using dispersive element(s)

    NASA Technical Reports Server (NTRS)

    Smith, David D. (Inventor)

    2010-01-01

    A ring-laser gyroscope system includes a ring-laser gyroscope (RLG) and at least one dispersive element optically coupled to the RLG's ring-shaped optical path. Each dispersive element has a resonant frequency that is approximately equal to the RLG's lasing frequency. A group index of refraction defined collectively by the dispersive element(s) has (i) a real portion that is greater than zero and less than one, and (ii) an imaginary portion that is less than zero.

  14. Element Research

    NSDL National Science Digital Library

    Mr. Wall

    2008-12-09

    You have been assigned an element during class. Your mission is to research information about your element. Create a Word document with the title of your element. Save your work regularly! Next, use the resources on this page to find and record the following information in your word document. (Hint: copy and paste the questions into your word document, then answer them.) See It s Elemental for electron configuration - ...

  15. TRACE ELEMENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Trace elements are defined as mineral elements that occur in living systems in micrograms per gram of body weight or less. Trace elements of greatest practical concern in human health are iodine, iron and zinc. Suggestive evidence is emerging that cobalt (as vitamin B12), copper, selenium, boron and...

  16. Plane Groups

    NSDL National Science Digital Library

    Dexter Perkins

    This is a lengthy PDF document (60 pages+) about plane groups and symmetry. It includes colorful images of each of the 17 plane groups, in several different forms. Additionally, there are some summarizing graphics that show unit cells, lattices, symmetry elements, etc. There is lots here to choose from -- I doubt that anyone will want to use all of the images. Studying plane groups is a good way to introduce crystal systems, point groups, lattices, symmetry operators, etc. All is in 2-D, but it is easy to tell students that the principles are the same in 3-D. For those who like to make changes, the PDF document was created from individual EPS files. This means that the files can be opened in Adobe Illustrator, Corel Draw, etc., and modified to fit your own needs.

  17. How Deep and Hot was Earth's Magma Ocean? Combined Experimental Datasets for the Metal-silicate Partitioning of 11 Siderophile Elements - Ni, Co, Mo, W, P, Mn, V, Cr, Ga, Cu and Pd

    NASA Technical Reports Server (NTRS)

    Righter, Kevin

    2008-01-01

    Since approximately 1990 high pressure and temperature (PT) experiments on metal-silicate systems have showed that partition coefficients (D) for siderophile (iron-loving) elements are much different than those measured at low PT conditions. The high PT data have been used to argue for a magma ocean during growth of the early Earth. Initial conclusions were based on experiments and calculations for a small number of elements such as Ni and Co. However, for many elements only a limited number of experimental data were available then, and they only hinted at values of metal-silicate D's at high PT conditions. In the ensuing decades there have been hundreds of new experiments carried out and published on a wide range of siderophile elements. At the same time several different models have been advanced to explain the siderophile elements in the earth's mantle: a) intermediate depth magma ocean; 25-30 GPa, b) deep magma ocean; up to 50 GPa, and c) early reduced and later oxidized magma ocean. Some studies have drawn conclusions based on a small subset of siderophile elements, or a set of elements that provides little leverage on the big picture (like slightly siderophile elements), and no single study has attempted to quantitatively explain more than 5 elements at a time. The purpose of this abstract is to update the predictive expressions outlined by Righter et al. (1997) with new experimental data from the last decade, test the predictive ability of these expressions against independent datasets (there are more data now to do this properly), and to apply the resulting expressions to the siderophile element patterns in Earth's upper mantle. The predictive expressions have the form: lnD = alnfO2 + b/T + cP/T + d(1Xs) + e(1Xc) + SigmafiXi + g These expressions are guided by the thermodynamics of simple metal-oxide equilibria that control each element, include terms that mimic the activity coefficients of each element in the metal and silicate, and quantify the effect of variable oxygen fugacity. Preliminary results confirm that D(Ni) and D(Co) converge at pressures near 25-30 GPa and approximately 2200 K, and show that D(Pd) and D(Cu) become too low at the PT conditions of the deepest models. Furthermore, models which force fit V and Cr mantle concentrations by metal-silicate equilibrium overlook the fact that at early Earth mantle fO2, these elements will be more compatible in Mg-perovskite and (Fe,Mg)O than in metal. Thus an intermediate depth magma ocean, at 25-30 GPa, 2200 K, and at IW-2, can explain more mantle siderophile element concentrations than other models.

  18. Data Elements Search - Data Elements

    Cancer.gov

     CDE  Cart  Home   FormBuilder   Help  Admin Tool  Curation Tool  NCI Metathesaurus  NCI Terminology Server  Sentinel Tool  UML Model Browser     What's new   Available DownloadsNew!   Data Element Search Search for Data Elements Search preferences

  19. Accelerator measurement of the energy spectra of neutrons emitted in the interaction of 3-GeV protons with several elements

    NASA Technical Reports Server (NTRS)

    Nalesnik, W. J.; Devlin, T. J.; Merker, M.; Shen, B. S. P.

    1972-01-01

    The application of time of flight techniques for determining the shapes of the energy spectra of neutrons between 20 and 400 MeV is discussed. The neutrons are emitted at 20, 34, and 90 degrees in the bombardment of targets by 3 GeV protons. The targets used are carbon, aluminum, cobalt, and platinum with cylindrical cross section. Targets being bombarded are located in the internal circulating beam of a particle accelerator.

  20. Microwave-assisted carbohydrohalogenation of first-row transition-metal oxides (M = V, Cr, Mn, Fe, Co, Ni, Cu) with the formation of element halides.

    PubMed

    Berger, Matthias; Neumeyer, Felix; Auner, Norbert

    2013-10-21

    The anhydrous forms of first-row transition-metal chlorides and bromides ranging from vanadium to copper were synthesized in a one-step reaction using the relatively inexpensive element oxides, carbon sources, and halogen halides as starting materials. The reactions were carried out in a microwave oven to give quantitative yields within short reaction times. PMID:24099620

  1. Hydroxypyridinonate complex stability of group (IV) metals and tetravalent f-block elements: the key to the next generation of chelating agents for radiopharmaceuticals.

    PubMed

    Sturzbecher-Hoehne, Manuel; Choi, Taylor A; Abergel, Rebecca J

    2015-04-01

    The solution thermodynamics of the water-soluble complexes formed between 3,4,3-LI(1,2-HOPO) and Zr(IV) or Pu(IV) were investigated to establish the metal coordination properties of this octadentate chelating agent. Stability constants log ?110 = 43.1 ± 0.6 and 43.5 ± 0.7 were determined for [Zr(IV)(3,4,3-LI(1,2-HOPO))] and [Pu(IV)(3,4,3-LI(1,2-HOPO))], respectively, by spectrophotometric competition titrations against Ce(IV). Such high thermodynamic stabilities not only confirm the unparalleled Pu(IV) affinity of 3,4,3-LI(1,2-HOPO) as a decorporation agent but also corroborate the great potential of hydroxypyridinonate ligands as new (89)Zr-chelating platforms for immuno-PET applications. These experimental values are in excellent agreement with previous estimates and are discussed with respect to ionic radius and electronic configuration, in comparison with those of Ce(IV) and Th(IV). Furthermore, a liquid chromatography assay combined with mass spectrometric detection was developed to probe the separation of the neutral [M(IV)(3,4,3-LI(1,2-HOPO))] complex species (M = Zr, Ce, Th, and Pu), providing additional insight into the coordination differences between group IV and tetravalent f-block metals and on the role of d and f orbitals in bonding interactions. PMID:25799124

  2. The 190Pt-186Os Decay System Applied to Dating Platinum-Group Element Mineralization in Layered Intrusions, Ophiolites and Detrital Deposits

    NASA Astrophysics Data System (ADS)

    Coggon, J. A.; Nowell, G.; Pearson, G.; Oberthür, T.; Lorand, J.; Melcher, F.; Parman, S. W.

    2010-12-01

    Discrete platinum-group minerals (PGM) occur as accessory phases in mafic-ultamafic intrusions and ophiolitic chromitites, as well as numerous detrital deposits globally. The 190Pt-186Os decay system, measured by laser ablation MC-ICPMS (LA-MC-ICPMS) provides a useful geochronometric tool for direct dating of PGM. Here we present two examples that verify the accuracy of the technique in geologically well constrained situations and demonstrate the potential for using the 190Pt-186Os PGM method to accurately date layered mafic intrusions, ophiolitic chromitites and detrital PGM deposits. Fifty PGM grains from three different horizons within the Bushveld complex yield a Pt-Os isochron age of 2012 ± 47 Ma (2?, MSWD = 1.19, 186Os/188Osi = 0.119818 ± 0.000006). This is consistent with the published U-Pb zircon age of 2054 Ma (Scoates and Friedman, 2008). The younger PGM isochron age is not likely to be a function of difference in blocking temperatures in the different systems. Pt-Os model ages are possible in high pt grains because initial 186Os/188Os can be well constrained. Using this approach we obtained Pt-Os model ages of 2113 ± 106 Ma and 2042 ± 102 Ma for a Bushveld Pt-Fe alloy and sperrylite respectively. Detrital PGM derived from the Meratus ophiolite, southeast Borneo yield a 190Pt-186Os isochron age of 202.5 Ma ± 8.3 Ma (2?, n = 260, MSWD = 0.90, 186Os/188Osi = 0.119830 ± 0.000003), consistent with radiometric and biostratigraphic age constraints (Wakita et al., 1998). We interpret this as the age of formation of the PGM grains in during chromitite genesis in the lower oceanic lithosphere. Our combined data demonstrate the utility of the LA-MC-ICPMS method as a tool for accurate Pt-Os dating of detrital PGM as well as their igneous parent bodies. We can constrain Pt/Os fractionation at the ablation site as being < 2.5%, while within-grain heterogeneity is ultimately one of the strongest controls on isochron and single-grain ages given the partial sampling represented by laser ablation. Scoates, J.S. and Friedman, R.M. 2008. Precise age of the platiniferous Merensky reef, Bushveld Complex, South Africa, by the U-Pb zircon chemical abrasion ID-TIMS technique; Economic Geology 103, p. 465-471. Wakita, K., Miyazaki, K., Zulkarnain, I., Sopaheluwakan, J. and Sanyoto, P. 1998. Tectonic implications of new age data for the Meratus complex of south Kalimantan, Indonesia; Island Arc 7, p. 202-222.

  3. Tissue trace and major element levels in organophosphate insecticide fenthion (Lebaycid) toxicity in rats: prophylactic and therapeutic effect of exogenous melatonin.

    PubMed

    Cemek, Mustafa; Emin Büyükokuro?lu, Mehmet; Yürümez, Yusuf; Yavuz, Yücel; Aslan, Adem; Büyükben, Ahmet; Aymelek, Fatih

    2010-02-01

    Organophosphate compounds are very toxic chemicals and used in widespread applications. The present study was designed to examine the role of exogenous melatonin against organophosphate toxicity in tissues (brain, heart, jejunum, kidney, liver, lung, muscle and pancreas) trace and major element levels of rats. Trace and major element concentrations in the tissues were measured in the sham group, the control group, prophylaxis with the melatonin group and therapy with the melatonin group (TM) by inductively coupled plasma-optical emission spectroscopy. Statistically significant differences among the experimental groups were detected for some tissue trace and major element concentrations. In the brain tissue, the Al, Mn and Se concentrations in the sham group were significantly higher than those in the control group (p<0.05). In the heart tissue, the Cu, Mn and Se concentrations in the sham group were significantly increased than those in the control group (p<0.05). In the kidney tissue, trace and major element concentrations in the TM group were significantly lower than those in the sham group (Fe and Mn; p<0.05, Cu, Mo, Ni, Ti, V and Zn; p<0.01). In the liver, Mg, Al, Zn and Ca concentrations in the TM group were significantly higher than those in the fenthion-treated control group (p<0.01). In the muscle tissue, element concentrations in the TM group were significantly lower when compared with the sham groups (Ca and Si; p<0.01). The Al, Cr, Mo, Ni, Si and Zn element concentrations were markedly decreased in the control group as compared with the TM group in the pancreas tissue (p<0.01). In conclusion, according to the results of the present study the major findings are that the fenthion-treated rat's tissue element levels were effected and the melatonin may normalize the altered levels of some trace and major elements of the tissues in organophosphate toxicity. PMID:19800688

  4. Toxicity of Arsenic (III) and (V) on Plant Growth, Element Uptake, and Total Amylolytic Activity of Mesquite (Prosopis Juliflora x P. Velutina)

    Microsoft Academic Search

    Ntebogeng S. Mokgalaka-Matlala; Edith Flores-Tavizón; Hiram Castillo-Michel; Jose R. Peralta-Videa; Jorge L. Gardea-Torresdey

    2008-01-01

    The effects of arsenite [As(III)] and arsenate [As(V)] on the growth of roots, stems, and leaves and the uptake of arsenic (As), micro- and macronutrients, and total amylolytic activity were investigated to elucidate the phytotoxicity of As to the mesquite plant (Prosopis juliflora x P. velutina). The plant growth was evaluated by measuring the root and shoot length, and the

  5. p-adic Groups Seminar / Study group

    E-print Network

    Carbone, Lisa

    , and accounts of it have been written by Tits and Satake. Tits compiled tables of `admissible indices' from which groups can be constructed. We describe Tits' tables for groups of relative rank 1 over non in pure and applied mathematics ; v. 3. [Ti1] Tits, J, Reductive groups over local fields, Automorphic

  6. Experimental determination of real elements of the density matrix and the dipole moment of H([ital n]=3) atoms produced from 20--100-keV H[sup +] on Ar

    SciTech Connect

    Renwick, S.P.; Martell, E.C.; Weaver, W.D.; Risley, J.S. (Atomic Collisions Laboratory, Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States))

    1993-10-01

    Diagonal and real off-diagonal coherence elements of the density matrix for H([ital n]=3) atoms produced in 20--100-keV electron-capture collisions of protons with Ar atoms are experimentally determined. Balmer-[alpha] light from the decay of H atoms from the ([ital n]=3) state to the ([ital n]=2) state is observed. The intensity and polarization of the light as a function of an axially symmetric electric field in the collision region are fitted to a numerical model of the H atom in an electric field in order to extract density-matrix elements. A new polarimeter, using a photoelastic modulator in conjunction with photon-counting techniques, is used in the experiment, and its efficacy is analyzed and compared to that of a rotating quarter-wave plate polarimeter previously used in similar experiments. The diagonal elements of the density matrix yield relative capture cross sections for the H(3[ital l]) angular-momentum substates, while the coherence terms are used to determine the dipole moment of the atoms produced. Results are compared to those for protons colliding with a He target and the differences are discussed.

  7. Combustion Group Group members

    E-print Network

    Wang, Wei

    Combustion Group Group members: Thierry Poinsot, Emilien Courtine, Luc Vervisch, Benjamin Farcy 2014 #12;Combustion Group Combustion Physics and Modeling Pollutants, Emissions, and Soot Formation Thermoacoustics and Combustion Dynamics Research focus § Examine mechanisms responsible for flame stabilization

  8. Nineteen trace elements in marine copepods collected from the coastal waters off northeastern Taiwan

    NASA Astrophysics Data System (ADS)

    Fang, Tien-Hsi; Hsiao, Shih-Hui; Nan, Fan-Hua

    2014-12-01

    This study analyzed nineteen trace elements in marine copepods collected from the coastal waters off Northeastern Taiwan. The bioconcentration factors (BCF) of the analyzed elements in copepods are discussed. Owing to the upwelling intrusion of Kuroshio Water, the study area presented an enriched copepod community and the copepod abundance ranged within 106-4890 ind. m-3. The trace elements content in the analyzed copepods varied substantially, ranging from 0.01 to 780 mg kg-1. and the average concentration followed the sequence: Sr>Fe>Zn>Cr>Li>Ni>Mn>Ba>Cu>Se>As>V>Pb>Rb>Cd>Co>Ga>Ag>Cs. The trace elements can be divided into five groups according to the concentration quantity in copepods: (1) Sr; (2) Fe, Zn, Cr, Li and Ni; (3) Mn, Cu, Ba, Se, As, V, Pb and Rb; (4) Cd, Co and Ga; (5) Ag and Cs. The concentration difference in each group is nearly one order of magnitude. The trace element concentrations in copepods seem to be in proportion to the dissolved concentrations in seawater. The trace element log BCF values ranged within 1.32-5.66. Transition metals generally have a higher BCF value than the associated minor elements, such as Ba, Sr, Li and Rb. The trace element BCF value in copepods is in inverse proportion to the dissolved concentrations in seawater.

  9. Comparison of linear strain triangular and tetrahedral elements with isoparametric elements in two- and three-dimensional finite element analyses 

    E-print Network

    Ho, Philip Wai-Sun

    1977-01-01

    COMPOSITE LINEAR STRAIN ELEMENTS 19 Ouadrilateral Element Stiffness Condensation Mass Condensation Three-Dimensional Brick Element 19 22 23 26 IV COMPARISON OF NUMERICAL RESULTS 31 Two-Dimensional Elements Eigenvalues Comparison Structural... Idealizations Dynamic Response Three-Dimensional Elements Structural Idealizations 31 31 34 42 42 47 V DISCUSSION AND CONCLUSIONS 52 Discussion Conclusions 52 53 REFERENCES 54 PAGE APPENDIX A ELASTICITY NATRICES APPENDIX B ISOPARAMETRIC SHAPE...

  10. Undercooling and supersaturation of alloying elements in rapidly solidified Al8.5% Fe1.2% V-1.7% Si alloy

    Microsoft Academic Search

    S. Hariprasad; S. M. L. Sastry; K. L. Jerina

    1996-01-01

    Dispersion-strengthened Al-8.5% Fe-1.2% V-1.7% Si alloy was produced by inert gas atomization and atomized melt deposition processes. Differential scanning calorimetry was used to estimate the extent of undercooling in the alloy powders as a function of powder size and in the atomized melt-deposited alloy as a function of process parameters. The estimated undercooling was found to be a strong function

  11. Measurement of spin correlations in top pair events in the lepton + jets channel with the matrix element method at $8 \\text{TeV}$

    E-print Network

    CMS Collaboration

    2015-01-01

    The consistency of the top quark pair events produced with standard model (SM) correlated spins is tested in the muon+jets final state. The events are obtained from $pp$ collisions at a center of mass energy of $\\sqrt{s} = 8 \\text{ TeV}$, corresponding to an integrated luminosity of $\\int Ldt\\, =\\, 19.7\\, \\text{fb}^{-1}$, collected with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC).

  12. Tevatron combination of single-top-quark cross sections and determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $\\bf V_{tb}$

    E-print Network

    CDF Collaboration; D0 Collaboration

    2015-03-17

    We present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb$^{-1}$ per experiment. The $t$-channel cross section is measured to be $\\sigma_t = 2.25^{+0.29}_{-0.31}$ pb. We also present the combinations of the two-dimensional measurements of the $s$- vs. $t$-channel cross sections and of the $s+t$ channel cross section measurement resulting in $\\sigma_{s+t} = 3.30^{+0.52}_{-0.40}$ pb, without assuming the standard-model value for the ratio $\\sigma_s/\\sigma_t$. The resulting value of the magnitude of the top-to-bottom quark coupling is $|V_{tb}|$ = $1.02^{+0.06}_{-0.05}$, corresponding to $|V_{tb}| > 0.92$ at the 95% C.L.

  13. Tevatron combination of single-top-quark cross sections and determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element $\\bf V_{tb}$

    E-print Network

    ,

    2015-01-01

    We present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb$^{-1}$ per experiment. The $t$-channel cross section is measured to be $\\sigma_t = 2.25^{+0.29}_{-0.31}$ pb. We also present the combinations of the two-dimensional measurements of the $s$- vs. $t$-channel cross sections and of the $s+t$ channel cross section measurement resulting in $\\sigma_{s+t} = 3.30^{+0.52}_{-0.40}$ pb, without assuming the standard-model value for the ratio $\\sigma_s/\\sigma_t$. The resulting value of the magnitude of the top-to-bottom quark coupling is $|V_{tb}|$ = $1.02^{+0.06}_{-0.05}$, corresponding to $|V_{tb}| > 0.92$ at the 95% C.L.

  14. Mass determination of hypervelocity microparticles using a piezoelectric PZT element

    NASA Astrophysics Data System (ADS)

    Miyachi, Takashi; Takechi, Seiji; Kawachi, Yuya; Shibata, Hiromi; Okudaira, Osamu; Kobayashi, Masanori; Nakamura, Maki; Iwai, Takeo; Gruen, Eberhard; Srama, Ralf

    A mass observed with a piezoelectric element is discussed using hypervelocity particles accel-erated by the Van de Graaff accelerator. Since the response of the PZT element is velocity-dependent, the particle mass can be derived using calibration formulas that depend on the velocity. When the velocity during collision exceeds 20 km/s, the piezoelectric element produces a pulsed signal. Then, the rise time and the amplitude of the pulsed signal are well correlated. If the rise time and the amplitude are measured pair off, the response to the collision is classified into three groups [1]. If the calibration formulas can be established in each group, the mass is determined. Let define the deviation by (1) (mm-m0)/m0 (1) where mm is the mass value obtained using the calibration formulas of each group and m0 is that by the time of flight method, respectively. The deviation distributes like a Gaussian form. The mass can be reproduced within 40 When the velocity is less than 10 km/s, the output is of a characteristic form, with which the collision time is exactly determined. The amplitude is subject not only to the particle momentum p but also to the charge q of particle. Then, the PZT element is sensitive to q before the particle arrives at the element during flight time t, if q ? 50 fC. Since the sensitive distance d is calibrated with respect to q, the velocity v and the mass m are obtained; v = d /t, and m = p/v. The deviation defined by (1) distributes like a Gaussian form. The mass can be reproduced described above. Reference [1] T.Miyachi et al., submitted for publication in Adv. Space Res.

  15. Chemical characterization of element 112.

    PubMed

    Eichler, R; Aksenov, N V; Belozerov, A V; Bozhikov, G A; Chepigin, V I; Dmitriev, S N; Dressler, R; Gäggeler, H W; Gorshkov, V A; Haenssler, F; Itkis, M G; Laube, A; Lebedev, V Ya; Malyshev, O N; Oganessian, Yu Ts; Petrushkin, O V; Piguet, D; Rasmussen, P; Shishkin, S V; Shutov, A V; Svirikhin, A I; Tereshatov, E E; Vostokin, G K; Wegrzecki, M; Yeremin, A V

    2007-05-01

    The heaviest elements to have been chemically characterized are seaborgium (element 106), bohrium (element 107) and hassium (element 108). All three behave according to their respective positions in groups 6, 7 and 8 of the periodic table, which arranges elements according to their outermost electrons and hence their chemical properties. However, the chemical characterization results are not trivial: relativistic effects on the electronic structure of the heaviest elements can strongly influence chemical properties. The next heavy element targeted for chemical characterization is element 112; its closed-shell electronic structure with a filled outer s orbital suggests that it may be particularly susceptible to strong deviations from the chemical property trends expected within group 12. Indeed, first experiments concluded that element 112 does not behave like its lighter homologue mercury. However, the production and identification methods used cast doubt on the validity of this result. Here we report a more reliable chemical characterization of element 112, involving the production of two atoms of (283)112 through the alpha decay of the short-lived (287)114 (which itself forms in the nuclear fusion reaction of 48Ca with 242Pu) and the adsorption of the two atoms on a gold surface. By directly comparing the adsorption characteristics of (283)112 to that of mercury and the noble gas radon, we find that element 112 is very volatile and, unlike radon, reveals a metallic interaction with the gold surface. These adsorption characteristics establish element 112 as a typical element of group 12, and its successful production unambiguously establishes the approach to the island of stability of superheavy elements through 48Ca-induced nuclear fusion reactions with actinides. PMID:17476264

  16. Cross sections for the production of residual nuclides by low- and medium-energy protons from the target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au

    NASA Astrophysics Data System (ADS)

    Michel, R.; Bodemann, R.; Busemann, H.; Daunke, R.; Gloris, M.; Lange, H.-J.; Klug, B.; Krins, A.; Leya, I.; Lüpke, M.; Neumann, S.; Reinhardt, H.; Schnatz-Büttgen, M.; Herpers, U.; Schiekel, Th.; Sudbrock, F.; Holmqvist, B.; Condé, H.; Malmborg, P.; Suter, M.; Dittrich-Hannen, B.; Kubik, P.-W.; Synal, H.-A.; Filges, D.

    1997-07-01

    Cross sections for residual nuclide production by p-induced reactions were measured from thresholds up to 2.6 GeV using accelerators at CERN/Geneve, IPN/Orsay, KFA/Jülich, LANL/Los Alamos, LNS/Saclay, PSI/Villigen, TSL/Uppsala, LUC/Louvain La Neuve. The target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au were investigated. Residual nuclides were measured by X- and ?-spectrometry and by Accelerator Mass Spectrometry (AMS). The measured cross sections were corrected for interfering secondary particles in experiments with primary proton energies above 200 MeV. Our consistent database covers presently ca 550 nuclear reactions and contains nearly 15000 individual cross sections of which about 10000 are reported here for the first time. They provide a basis for model calculations of the production of cosmogenic nuclides in extraterrestrial matter by solar and galactic cosmic ray protons. They are of importance for many other applications in which medium energy nuclear reactions have to be considered ranging from astrophysics over space and environmental sciences to accelerator technology and accelerator-based nuclear waste transmutation and energy amplification. The experimental data are compared with theoretical ones based on calculations using an INC/E model in form of the HETC/KFA2 code and on the hybrid model of preequilibrium reactions in form of the AREL code.>

  17. Cross sections for neutron-induced reactions up to 1.6 GeV for target elements relevant for cosmochemical, geochemical, and technological applications

    NASA Astrophysics Data System (ADS)

    Leya, Ingo; Michel, Rolf

    2011-11-01

    We determined neutron excitation functions from the respective reaction thresholds up to 1.6 GeV for almost 100 target-product combinations relevant for cosmochemical, geochemical, and technological applications. We started with thick target production rates that have been obtained by irradiating iron and stone spheres with protons having energies between 600 MeV and 1.6 GeV. From the particle spectra of primary protons, secondary protons, and secondary neutrons, and the usually well known cross sections for the proton-induced reactions we calculated the production rates only due to protons. By subtracting these data from the measured total production rates we obtained production rates only due to secondary neutrons. With the modelled neutron spectra, guess functions calculated using nuclear model codes, and sophisticated energy-dependent deconvolution procedures we were able to determine almost 100 neutron excitation functions with their uncertainties. With the thus obtained neutron cross sections we are able to describe the experimental production rates in the thick target experiments, meteorites, the lunar surface, and terrestrial surface samples usually within the uncertainties, i.e., to within 10-15%. The adjusted neutron cross sections ( a posteriori) are compared to results from the theoretical nuclear model codes INCL4.5/ABLA07 and TALYS. The TALYS code usually describes the a posteriori data reasonably well, i.e., mostly within a factor of a few. The quality of the INCL4.5 + ABLA07 predictions depends on the reaction type and increases with increasing number of ejectiles, i.e., increasing target-product mass difference. The neutron cross section database, though successful in quantifying production rates in terrestrial and extraterrestrial matter, presents by no means a final step and experiments with quasi-monoenergetic neutrons are needed.

  18. TROPODEGRADABLE HALOCARBONS AND MAIN GROUP ELEMENT COMPOUNDS

    EPA Science Inventory

    Although it is not certain that a "drop-in" chemical substitute (as opposed to a new technology) for halons that can be used in normally occupied areas will ever be identified, there are two promising paths to such an agent. The first is to target bromocarbons with very short atm...

  19. Selective oxidation of H 2 S to ammonium thiosulfate and elemental sulfur using mixtures of V-Bi-O and Sb 2 O 4

    Microsoft Academic Search

    Bong-Kuk Kim; Byung-Ha Hwang; Hwa-Soo Lee; Hee-Chul Woo; Dae-Won Park

    2004-01-01

    The selective oxidation of hydrogen sulfide in the presence of excess water and ammonia was investigated by using vanadium-bismuth\\u000a based mixed oxide catalysts. Synergistic effect on catalytic activity was observed for the mechanical mixtures of V-Bi-O and\\u000a Sb2O4. Temperature programmed oxidation (TPO), X-ray photoelectron spectroscopy (XPS), and two separated bed reactivity test results\\u000a supported the role of Sb2O4 for reoxidizing

  20. Superheavy Elements

    ERIC Educational Resources Information Center

    Tsang, Chin Fu

    1975-01-01

    Discusses the possibility of creating elements with an atomic number of around 114. Describes the underlying physics responsible for the limited extent of the periodic table and enumerates problems that must be overcome in creating a superheavy nucleus. (GS)

  1. Element Hangman

    NSDL National Science Digital Library

    The Thomas Jefferson National Accelerator Facility, known as the Jefferson Lab, is funded by the Office of Science for the US Department of Energy. Its corresponding Web site and educational offerings include the interactive Element Hangman game. This simple exercise requires kids to enter the correct letters of an element before all ten pieces of the animated figure are gone. However, the highlight of the site is that, once the correct element is spelled, students get to click the "tell me more about" button for additional information. A separate window opens, which gives a wealth of facts about that element such as its physical properties, who discovered it, and what it's used in. This and other related games provided by the site offer a great way for kids to have fun while learning.

  2. Elemental Education.

    ERIC Educational Resources Information Center

    Daniel, Esther Gnanamalar Sarojini; Saat, Rohaida Mohd.

    2001-01-01

    Introduces a learning module integrating three disciplines--physics, chemistry, and biology--and based on four elements: carbon, oxygen, hydrogen, and silicon. Includes atomic model and silicon-based life activities. (YDS)

  3. elemental discoveries

    NSDL National Science Digital Library

    Experienced science journalist David Bradley serves up this resource on current chemical happenings. Tracking some of the discoveries and controversies at the forefront of chemistry, each issue of elemental discoveries summarizes a range of newsworthy topics, from gene control and tubular sensors to singing fish. In addition to the current issue, readers may browse past issues beginning December 1997. Two additional sections, Elemental Reviews and Book Sale, provide brief commentary on or descriptions (with UK prices) of related resources.

  4. 47 CFR 13.203 - Examination elements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...8: Ship radar techniques. Questions concerning specialized theory and practice applicable to the proper installation, servicing...AR, BT, and SK. (1) Telegraphy Element 1: 16 code groups per minute. (2) Telegraphy Element 2: 20 words per...

  5. 47 CFR 13.203 - Examination elements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...8: Ship radar techniques. Questions concerning specialized theory and practice applicable to the proper installation, servicing...AR, BT, and SK. (1) Telegraphy Element 1: 16 code groups per minute. (2) Telegraphy Element 2: 20 words per...

  6. Group V Phospholipase A2 in Bone Marrow-derived Myeloid Cells and Bronchial Epithelial Cells Promotes Bacterial Clearance after Escherichia coli Pneumonia*

    PubMed Central

    Degousee, Norbert; Kelvin, David J.; Geisslinger, Gerd; Hwang, David M.; Stefanski, Eva; Wang, Xing-Hua; Danesh, Ali; Angioni, Carlo; Schmidt, Helmut; Lindsay, Thomas F.; Gelb, Michael H.; Bollinger, James; Payré, Christine; Lambeau, Gérard; Arm, Jonathan P.; Keating, Armand; Rubin, Barry B.

    2011-01-01

    Group V-secreted phospholipase A2 (GV sPLA2) hydrolyzes bacterial phospholipids and initiates eicosanoid biosynthesis. Here, we elucidate the role of GV sPLA2 in the pathophysiology of Escherichia coli pneumonia. Inflammatory cells and bronchial epithelial cells both express GV sPLA2 after pulmonary E. coli infection. GV?/? mice accumulate fewer polymorphonuclear leukocytes in alveoli, have higher levels of E. coli in bronchoalveolar lavage fluid and lung, and develop respiratory acidosis, more severe hypothermia, and higher IL-6, IL-10, and TNF-? levels than GV+/+ mice after pulmonary E. coli infection. Eicosanoid levels in bronchoalveolar lavage are similar in GV+/+ and GV?/? mice after lung E. coli infection. In contrast, GV+/+ mice have higher levels of prostaglandin D2 (PGD2), PGF2?, and 15-keto-PGE2 in lung and express higher levels of ICAM-1 and PECAM-1 on pulmonary endothelial cells than GV?/? mice after lung infection with E. coli. Selective deletion of GV sPLA2 in non-myeloid cells impairs leukocyte accumulation after pulmonary E. coli infection, and lack of GV sPLA2 in either bone marrow-derived myeloid cells or non-myeloid cells attenuates E. coli clearance from the alveolar space and the lung parenchyma. These observations show that GV sPLA2 in bone marrow-derived myeloid cells as well as non-myeloid cells, which are likely bronchial epithelial cells, participate in the regulation of the innate immune response to pulmonary infection with E. coli. PMID:21849511

  7. Pentaatomic planar tetracoordinate silicon with 14 valence electrons: a large-scale global search of SiX(n)Y(m)(q) (n?+?m?=?4; q?=?0, ±1, -2; X, Y?=?main group elements from H to Br).

    PubMed

    Xu, Jing; Ding, Yi-hong

    2015-03-01

    Designing and characterizing the compounds with exotic structures and bonding that seemingly contrast the traditional chemical rules are a never-ending goal. Although the silicon chemistry is dominated by the tetrahedral picture, many examples with the planar tetracoordinate-Si skeletons have been discovered, among which simple species usually contain the 17/18 valence electrons. In this work, we report hitherto the most extensive structural search for the pentaatomic ptSi with 14 valence electrons, that is, SiXnYm(q) (n?+?m?=?4; q?=?0, ±1, -2; X, Y?=?main group elements from H to Br). For 129 studied systems, 50 systems have the ptSi structure as the local minimum. Promisingly, nine systems, that is, Li3SiAs(2-), HSiY3 (Y?=?Al/Ga), Ca3SiAl(-), Mg4Si(2-), C2LiSi, Si3Y2 (Y?=?Li/Na/K), each have the global minimum ptSi. The former six systems represent the first prediction. Interestingly, in HSiY3 (Y?=?Al/Ga), the H-atom is only bonded to the ptSi-center via a localized 2c-2e ? bond. This sharply contradicts the known pentaatomic planar-centered systems, in which the ligands are actively involved in the ligand-ligand bonding besides being bonded to the planar center. Therefore, we proposed here that to generalize the 14e-ptSi, two strategies can be applied as (1) introducing the alkaline/alkaline-earth elements and (2) breaking the peripheral bonding. In light of the very limited global ptSi examples, the presently designed six systems with 14e are expected to enrich the exotic ptSi chemistry and welcome future laboratory confirmation. PMID:25430676

  8. Local Group(s)

    E-print Network

    Eva K. Grebel

    2006-05-22

    The properties of the galaxies of the Local Group are reviewed, followed by a brief discussion of nearby groups. The galaxy groups in our vicinity - the M81 group, the Cen A group, and the IC 342/Maffei group - are in many respects Local Group analogs: Their luminosity functions, galaxy content, fractional galaxy type distribution, crossing times, masses, and zero-velocity surface radii are similar to those of the Local Group. Also, the nearby groups usually consist of two subgroups, some of which approach each other and may ultimately merge to form a fossil group. These poor groups contrast with the less evolved, loose and extended galaxy ``clouds'' such as the Scl group and the CVn I cloud. These are characterized by long crossing times, are dominated by gas-rich, late-type galaxies, and lack gas-deficient, low luminosity early-type dwarfs. These clouds may be groups still in formation. The local Hubble flow derived from the clouds and groups is very cold.

  9. A calculation of the neutron emission spectra and the neutron number produced by (p, n) reaction for some thick targets composed of heavy elements from 0.5 GeV to 3.0 GeV

    NASA Astrophysics Data System (ADS)

    Thu, Nguyen Thi Ai; Mong Giao, Nguyen

    2013-03-01

    The calculation of neutron multiplicity and its energy spectra in (p,n) reactions are very important and necessary for designing and manufacturing the target for an Accelerator Driven System (ADS). The neutron multiplicity in (p,n) reactions on different thin targets with different proton beam energies has been presented in the JENDL-HE library. However, the target used in the ADS must be thick so that the number of neutrons produced is as large as possible. For this reason, we can't directly use the results in the JENDL-HE library. In this paper, we calculate neutron emission spectra and multiplicity in (p,n) reactions for some thick target nuclei including Pb204, Pb206, Pb207, Pb208, W180, W182 W184 W186, U235, U238, Au197 with proton beam energies ranging from 0.5 GeV to 3.0 GeV.

  10. Simple groups stabilizing polynomials

    E-print Network

    Skip Garibaldi; Robert Guralnick

    2015-04-28

    We study the problem of determining, for a polynomial function $f$ on a vector space $V$, the linear transformations $g$ of $V$ such that $f g = f$. In case $f$ is invariant under a simple algebraic group $G$ acting irreducibly on $V$, we note that the subgroup of $GL(V)$ stabilizing $f$ often has identity component $G$ and we give applications realizing various groups, including the largest exceptional group $E_8$, as automorphism groups of polynomials and algebras. We show that starting with a simple group $G$ and an irreducible representation $V$, one can almost always find an $f$ whose stabilizer has identity component $G$ and that no such $f$ exists in the short list of excluded cases. This relies on our core technical result, the enumeration of inclusions $G complex numbers.

  11. Measurement of the t-channel single-top-quark production cross section and of the |Vtb| CKM matrix element in pp collisions at sqrt(s) = 8 TeV

    SciTech Connect

    Khachatryan, V. [Yerevan Physics Institute (Armenia); et al.,

    2014-06-01

    Measurements are presented of the t-channel single-top-quark production cross section in proton-proton collisions at ?s = 8 TeV. The results are based on a data sample corresponding to an integrated luminosity of 19.7 fb?¹ recorded with the CMS detector at the LHC. The cross section is measured inclusively, as well as separately for top (t) and antitop $ \\left(\\overline{\\mathrm{t}}\\right) $ , in final states with a muon or an electron. The measured inclusive t-channel cross section is ?t-ch. = 83.6 ± 2.3 (stat.) ± 7.4 (syst.) pb. The single t and $ \\overline{\\mathrm{t}} $ cross sections are measured to be ?t-ch.(t) = 53.8 ± 1.5 (stat.) ± 4.4 (syst.) pb and ?$_{t-ch.}$ $ \\left(\\overline{t}\\right) $ = 27.6 ± 1.3 (stat.) ± 3.7 (syst.) pb, respectively. The measured ratio of cross sections is Rt-ch. = ?t-ch.(t)/?t-ch. $ \\left(\\overline{\\mathrm{t}}\\right) $ = 1.95 ± 0.10 (stat.) ± 0.19 (syst.), in agreement with the standard model prediction. The modulus of the Cabibbo-Kobayashi-Maskawa matrix element Vtb is extracted and, in combination with a previous CMS result at ?s = 7 TeV, a value |Vtb| = 0.998 ± 0.038 (exp.) ± 0.016 (theo.) is obtained.

  12. Actinide collisions for QED and superheavy elements with the time-dependent Hartree-Fock theory and the Balian-V\\'en\\'eroni variational principle

    E-print Network

    Simenel, Cédric; Kedziora, David J

    2011-01-01

    Collisions of actinide nuclei form, during very short times of few zs ($10^{-21}$ s), the heaviest ensembles of interacting nucleons available on Earth. Such collisions are used to produce super-strong electric fields by the huge number of interacting protons to test spontaneous positron-electron pair emission (vacuum decay) predicted by the quantum electrodynamics (QED) theory. Multi-nucleon transfer in actinide collisions could also be used as an alternative way to fusion in order to produce neutron-rich heavy and superheavy elements thanks to inverse quasifission mechanisms. Actinide collisions are studied in a dynamical quantum microscopic approach. The three-dimensional time-dependent Hartree-Fock (TDHF) code {\\textsc{tdhf3d}} is used with a full Skyrme energy density functional to investigate the time evolution of expectation values of one-body operators, such as fragment position and particle number. This code is also used to compute the dispersion of the particle numbers (e.g., widths of fragment mass...

  13. Combustion Group Group members

    E-print Network

    Wang, Wei

    Combustion Group Group members: Thierry Poinsot, Emilien Courtine, Luc Vervisch, Benjamin Farcy § New combustion and energy-conversion concepts #12;Introduction Combustion research thrusts Combustion Dynamics and Flame-Stabilization Research objectives § Obtain fundamental understanding of combustion

  14. Six Essential Elements- National Geographic Photograph Activity

    NSDL National Science Digital Library

    Patricia Steed

    2012-08-01

    This lesson is the fourth in a unit of five lessons on the Six Essential Elements of Geography. In this lesson students will apply recently acquired knowledge regarding the Six Essential Elements of Geography. They will utilize National Geographic magazines to find examples of the six Elements and write to explain how the photograph fits the element. First, they will do this activity in groups; groups will each be assigned one Element. Second, students will individually find an example of all six Elements. At the end of the lesson, students will present their work to the class.

  15. Experimental determination of the real elements of the density matrix of H({ital n}=3) atoms produced in 20--100-keV collisions of H{sup +} on Kr

    SciTech Connect

    Seifert, N.; Gibson, N.D.; Risley, J.S. [Atomic Collision Laboratory, Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States)] [Atomic Collision Laboratory, Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202 (United States)

    1995-11-01

    In continuation of our previous work, charge transfer processes occurring in protons on rare-gas-atom collisions have been investigated. Diagonal and real off-diagonal coherence elements of the density matrix for H({ital n}=3) atoms produced in 20--100-keV electron-capture collisions with Kr atoms are experimentally determined by analyzing the Balmer-{alpha} light from the decay of H atoms from the ({ital n}=3) state to the ({ital n}=2) state. The intensity and polarization of the emitted light are measured as functions of an axially symmetric electric field in the collision region. These data are fitted to a numerical model of the H atom in an electric field in order to extract density-matrix elements. The results are compared to previous studies of H{sup +} on He and Ar. The collisionally produced dipole moment of the H({ital n}=3) atom decreases for increasing atomic number of the rare-gas target atoms, which indicates that the final phase of the collision process is not essential for the formation of the dipole moment. This physical picture is further supported by our alignment data. Absolute cross sections for charge transfer to the 3{ital s}, 3{ital p}, and 3{ital d} levels are presented as well.

  16. Seroprotective Antibodies to 2011 Variant Influenza A(H3N2v) and Seasonal Influenza A(H3N2) among Three Age Groups of US Department of Defense Service Members

    PubMed Central

    Radin, Jennifer M.; Hawksworth, Anthony W.; Ortiguerra, Ryan G.; Brice, Gary T.

    2015-01-01

    Background In 2011, a new variant of influenza A(H3N2) emerged that contained a recombination of genes from swine H3N2 viruses and the matrix (M) gene of influenza A(H1N1)pdm09 virus. New combinations and variants of pre-existing influenza viruses are worrisome if there is low or nonexistent immunity in a population, which increases chances for an outbreak or pandemic. Methods Sera collected in 2011 were obtained from US Department of Defense service members in three age groups: 19–21 years, 32–33 years, and 47–48 years. Pre- and post-vaccination samples were available for the youngest age group, and postvaccination samples for the two older groups. Specimens were tested using microneutralization assays for antibody titers against H3N2v (A/Indiana/10/2011) and seasonal H3N2 virus (A/Perth/16/2009). Results The youngest age group had significantly (p<0.05) higher geometric mean titers for H3N2v with 165 (95% confidence interval [CI]: 105–225) compared with the two older groups, aged 32–33 and 47–48 years, who had geometric mean titers of 68 (95% CI: 55–82) and 46 (95% CI: 24–65), respectively. Similarly, the youngest age group also had the highest geometric mean titers for seasonal H3N2. In the youngest age group, the proportion of patients who seroconverted after vaccination was 12% for H3N2v and 27% for seasonal H3N2. Discussion Our results were similar to previous studies that found highest seroprotection among young adults and decreasing titers among older adults. The proportion of 19- to 21-year-olds who seroconverted after seasonal vaccination was low and similar to previous findings. Improving our understanding of H3N2v immunity among different age groups in the United States can help inform vaccination plans if H3N2v becomes more transmissible in the future. PMID:25816244

  17. The four-loop renormalization group QCD and QED $?$-functions in the $V$-scheme and their analogy with the Gell-Mann--Low function in QED and QCD

    E-print Network

    A. L. Kataev; V. S. Molokoedov

    2015-04-24

    The semi-analytical expression for the forth coefficient of the renormalization group $\\beta$-function in the ${\\rm{V}}$-scheme is obtained in the case of the $SU(N_c)$ gauge group. In the process of calculations we use the three-loop perturbative approximation for the QCD static potential, evaluated in the $\\rm{\\overline{MS}}$-scheme. The importance of getting more detailed expressions for the $n_f$-independent three-loop contribution to the static potential,obtained at present by two groups, is emphasised. The comparison of the numerical structure of the four-loop approximations for the RG $\\beta$- function of QCD in the gauge-independent ${\\rm{V}}$- and $\\rm{\\overline{MS}}$-schemes and in the minimal MOM scheme in the Landau gauge are presented. Considering the limit of QED with $N$-types of leptons we discover that the $\\beta^{\\rm{V}}$-function is starting to differ from the Gell-Mann--Low function $\\Psi(\\alpha_{\\rm{MOM}})$ at the level of the forth-order perturbative corrections, receiving the proportional to $N^2$ additional term. Taking this feature into account, we propose to consider the $\\beta^{\\rm{V}}$-function as the most theoretically substantiated analog of the Gell-Man--Low function in QCD.

  18. Role of vanadium (V) in the differentiation of C3H10t1/2 cells towards osteoblast lineage: a comparative analysis with other trace elements.

    PubMed

    Srivastava, Swati; Kumar, Narender; Thakur, Rajani Salunke; Roy, Partha

    2013-04-01

    In recent time, vanadium compounds are being used as antidiabetic drug and in orthopedic implants. However, the exact role of this incorporated vanadium in improving the quality of bone structure and morphology is not known. The impact of vanadium ion was studied and compared to other trace metal ions with respect to the proliferation and osteoblast differentiation of C3H10t1/2 cells. Toxicity profile of these trace metal ions revealed a descending toxicity trend of Fe(2+) > Zn(2+) > Cu(2+) > Co(2+) > Mn(2+) > V(5+) > Cr(2+). The effect of vanadium and other trace metal ions on osteoblast differentiation was evaluated by culturing the cells for 10 days in osteoblastic medium supplemented with different trace ions at concentrations lower than their cytotoxic doses. The results indicated that vanadium has maximum impact on the induction of osteoblast differentiation by upregulating alkaline phosphatase activity and mineralization by up to 145 and 150 %, respectively (p?

  19. KAOS/LIB-V: A library of nuclear response functions generated by KAOS-V code from ENDF/B-V and other data files

    SciTech Connect

    Farawila, Y.; Gohar, Y.; Maynard, C.

    1989-04-01

    KAOS/LIB-V: A library of processed nuclear responses for neutronics analyses of nuclear systems has been generated. The library was prepared using the KAOS-V code and nuclear data from ENDF/B-V. The library includes kerma (kinetic energy released in materials) factors and other nuclear response functions for all materials presently of interest in fusion and fission applications for 43 nonfissionable and 15 fissionable isotopes and elements. The nuclear response functions include gas production and tritium-breeding functions, and all important reaction cross sections. KAOS/LIB-V employs the VITAMIN-E weighting function and energy group structure of 174 neutron groups. Auxiliary nuclear data bases, e.g., the Japanese evaluated nuclear data library JENDL-2 were used as a source of isotopic cross sections when these data are not provided in ENDF/B-V files for a natural element. These are needed mainly to estimate average quantities such as effective Q-values for the natural element. This analysis of local energy deposition was instrumental in detecting and understanding energy balance deficiencies and other problems in the ENDF/B-V data. Pertinent information about the library and a graphical display of the main nuclear response functions for all materials in the library are given. 35 refs.

  20. Glueball matrix elements: a lattice calculation and applications

    NASA Astrophysics Data System (ADS)

    Meyer, Harvey B.

    2009-01-01

    We compute the matrix elements of the energy-momentum tensor between glueball states and the vacuum in SU(3) lattice gauge theory and extrapolate them to the continuum. These matrix elements may play an important phenomenological role in identifying glue-rich mesons. Based on a relation derived long ago by the ITEP group for J/? radiative decays, the scalar matrix element leads to a branching ratio for the glueball that is at least three times larger than the experimentally observed branching ratio for the f0 mesons above 1GeV. This suggests that the glueball component must be diluted quite strongly among the known scalar mesons. Finally we review the current best continuum determination of the scalar and tensor glueball masses, the deconfining temperature, the string tension and the Lambda parameter, all in units of the Sommer reference scale, using calculations based on the Wilson action.

  1. Search for standard model Higgs boson production in association with a W boson using a matrix element technique at CDF in pp? collisions at ?s=1.96 TeV

    DOE PAGESBeta

    Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; et al

    2012-04-01

    This paper presents a search for standard model Higgs boson production in association with a W boson using events recorded by the CDF experiment in a data set corresponding to an integrated luminosity of 5.6 fb?¹. The search is performed using a matrix element technique in which the signal and background hypotheses are used to create a powerful discriminator. The discriminant output distributions for signal and background are fit to the observed events using a binned likelihood approach to search for the Higgs boson signal. We find no evidence for a Higgs boson, and 95% confidence level (C.L.) upper limitsmore »are set on ?(pp??WH)×B(H?bb¯). The observed limits range from 3.5 to 37.6 relative to the standard model expectation for Higgs boson masses between mH=100 GeV/c² and mH=150 GeV/c². The 95% C.L. expected limit is estimated from the median of an ensemble of simulated experiments and varies between 2.9 and 32.7 relative to the production rate predicted by the standard model over the Higgs boson mass range studied.« less

  2. Search for Standard Model Higgs Boson Production in Association with a $W$ Boson Using a Matrix Element Technique at CDF in $p\\bar{p}$ Collisions at $\\sqrt{s} = 1.96$ TeV

    SciTech Connect

    Aaltonen, T.; /Helsinki Inst. of Phys.; Alvarez Gonzalez, B.; /Oviedo U. /Cantabria Inst. of Phys.; Amerio, S.; /INFN, Padua; Amidei, D.; /Michigan U.; Anastassov, A.; /Northwestern U. /Fermilab; Annovi, A.; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Appel, J.A.; /Fermilab; Arisawa, T.; /Waseda U.; Artikov, A.; /Dubna, JINR /Texas A-M

    2011-12-01

    This paper presents a search for standard model Higgs boson production in association with a W boson using events recorded by the CDF experiment in a dataset corresponding to an integrated luminosity of 5.6 fb{sup -1}. The search is performed using a matrix element technique in which the signal and background hypotheses are used to create a powerful discriminator. The discriminant output distributions for signal and background are fit to the observed events using a binned likelihood approach to search for the Higgs boson signal. We find no evidence for a Higgs boson, and 95% confidence level (C.L.) upper limits are set on {sigma}(p{bar p} {yields} WH) x {Beta}(H {yields} b{bar b}). The observed limits range from 3.5 to 37.6 relative to the standard model expectation for Higgs boson masses between m{sub H} = 100 GeV/c{sup 2} and m{sub H} = 150 GeV/c{sup 2}. The 95% C.L. expected limit is estimated from the median of an ensemble of simulated experiments and varies between 2.9 and 32.7 relative to the production rate predicted by the standard model over the Higgs boson mass range studied.

  3. Element Report

    NSDL National Science Digital Library

    Mrs. Petersen

    2014-04-07

    Use these resources to fill out your Element Report outline Today's project is slightly different than those you've done in the past. You are not required to follow these sites in order. You can use any or all of them to find out the information needed for your outline. You should access at least three of the sites. The first four sites ...

  4. RADIATIVE LIFETIMES OF V I AND V II

    SciTech Connect

    Den Hartog, E. A.; Lawler, J. E.; Wood, M. P., E-mail: eadenhar@wisc.edu, E-mail: jelawler@wisc.edu, E-mail: mpwood@wisc.edu [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)

    2014-11-01

    New radiative lifetimes are reported for 168 levels of V I ranging in energy from 18086 cm{sup –1} to 47702 cm{sup –1}, and for 31 levels of V II ranging in energy from 34593 cm{sup –1} to 47420 cm{sup –1}. These lifetimes are measured using time-resolved laser-induced fluorescence on a slow atomic/ionic beam as part of an ongoing study of the radiative properties of the iron group elements. All but two of the V II lifetimes have been measured before using modern laser-based methods, but a large fraction of the V I lifetimes are reported here for the first time. Comparison to earlier measurements is discussed. These new lifetimes are, for the most part, accurate to ±5%. They will be combined with branching fraction measurements to produce a large set of transition probabilities for V I and V II which are needed by the astrophysics community for stellar abundance determinations.

  5. A Group Leadership Exercise.

    ERIC Educational Resources Information Center

    Meyer, John; Stafford, Jeff

    A group leadership exercise that incorporates the elements of leadership and other aspects of interaction within small groups can be useful in a basic communication course. The exercise is designed around three basic leadership styles: laissez-faire, democratic, and authoritarian. The exercise is conducted in the following way: (1) the class…

  6. Continuing spectroscopic observations (3600-8800A) of V339 Del = Nova Del 2013 in the early nebular stage with the Nordic Optical Telescope, Ondrejov Observatory and the ARAS group

    NASA Astrophysics Data System (ADS)

    Shore, S. N.; Cechura, J.; Korcakova, D.; Kubat, J.; Skoda, P.; Slechta, M.; Votruba, V.; Alton, K.; Antao, D.; Barbotin, E.; Berardi, P.; Blank, T.; Bohlsen, P.; Boubault, F.; Boyd, D.; Briol, J.; Buchet, Y.; Buil, C.; Charbonnel, S.; Dubreuil, P.; Dubs, M.; Edlin, J.; France, T. de; Favaro, A.; Gerlach, P.; Garde, O.; Graham, K.; Greenan, D.; Guarro, J.; Hansen, T.; Hyde, D.; Lemoult, T.; Leadbeater, R.; Martineau, G.; Masviel, J. P.; Mauclaire, B.; Montier, J.; Pollmann, E.; Potter, M.; Ribeiro, J.; Schramm, B.; Thizy, O.; Terry, J.-N.; Teyssier, F.

    2013-11-01

    We have been continuing almost nightly spectroscopic observations of V339 Del (see ATel#5378) with the 2.6 m Nordic Optical Telecope (NOT) FIbre-fed Echelle Spectrograph (FIES) (R ~ 67000), the Ondrejov Observatory 2m Zeiss coude spectrograph (R = 18000), and a variety of grating and echelle spectrographs of the ARAS group in the wavelength range 3684 - 7431A with resolutions ranging from 580 - 12000.

  7. Superheavy Elements

    Microsoft Academic Search

    S. Hofmann

    2009-01-01

    The nuclear shell model predicts that the next doubly magic shell closure beyond 208Pb is at a proton number Z=114, 120, or 126 and at a neutron number N=172 or 184. The outstanding aim of experimental investigations\\u000a is the exploration of this region of spherical ‘SuperHeavy Elements’ (SHEs). Experimental methods have been developed which\\u000a allowed for the identification of new

  8. CORRIGENDUM CLONES OF FINITE GROUPS

    E-print Network

    Kearnes, Keith A.

    CORRIGENDUM CLONES OF FINITE GROUPS KEITH A. KEARNES AND ´AGNES SZENDREI 1. The Clone of the Quaternion Group We proved in Clones of finite groups, [1], that any operation on the 8-element quaternion group Q8 that preserves all the 5-ary algebraic relations of Q8 is in the clone of Q8

  9. Trading group theory for randomness

    Microsoft Academic Search

    László Babai

    1985-01-01

    In a previous paper [BS] we proved, using the elements of the theory of nilpotent groups, that some of the fundamental computational problems in matriz groups belong to NP. These problems were also shown to belong to coNP, assuming an unproven hypothesis concerning finite simple groups.The aim of this paper is to replace most of the (proven and unproven) group

  10. Abelian groups

    E-print Network

    Bolen, James Cordell

    1956-01-01

    s a 1-1 mapping. Also (na + ma)c' [(n + m)a]c ge (n + m)b ra nb + mb gt (na)c + (ma)o. Thus a is a homomorphism, and th1s together with the above tells us that a is an isomorphism. Hence (2) is proved, and thus the theorem, Definition 2e6 If a... as 0. But z 0 + 0 ~ 0, This tells us a is an isomorphism. Iet (Si) be any finite or infin1te set of subgroups of a group G. In this thesis, the general way that we w111 show G 1s a d. lrect sum of these subgroups will be to (l) show every element...

  11. Sortable Elements for Quivers with Cycles

    E-print Network

    Reading, Nathan

    Each Coxeter element c of a Coxeter group W defines a subset of W called the c-sortable elements. The choice of a Coxeter element of W is equivalent to the choice of an acyclic orientation of the Coxeter diagram of W. In ...

  12. Elemental Analysis using Pulsed Neutrons

    NASA Astrophysics Data System (ADS)

    Houchins, Eric; Womble, Phillip; Barzilov, Alexander; Paschal, Jon; Rice, Ian; Board, Jeremy; Howard, Joeseph

    2006-10-01

    Elemental analysis using pulsed fast neutrons is a method in which elemental compounds can be analyzed during neutron bombardment using a pulsed d-T neutron generator. The 14 MeV neutrons impinging upon a material create a plethora of nuclear reactions including (n,n'), (n,p), (n,?), etc. Each isotope has a specific gamma ray pattern which leads to isotope identification and the intensity of each gamma ray can determine the relative amount of that isotope. From the elemental densities, the threat potential can be discerned. We will discuss the methodology as well as a recent examination of 53 naval ordnance items found in Yorktown VA.

  13. Intelligent Elements for ISHM

    NASA Technical Reports Server (NTRS)

    Schmalzel, John L.; Morris, Jon; Turowski, Mark; Figueroa, Fernando; Oostdyk, Rebecca

    2008-01-01

    There are a number of architecture models for implementing Integrated Systems Health Management (ISHM) capabilities. For example, approaches based on the OSA-CBM and OSA-EAI models, or specific architectures developed in response to local needs. NASA s John C. Stennis Space Center (SSC) has developed one such version of an extensible architecture in support of rocket engine testing that integrates a palette of functions in order to achieve an ISHM capability. Among the functional capabilities that are supported by the framework are: prognostic models, anomaly detection, a data base of supporting health information, root cause analysis, intelligent elements, and integrated awareness. This paper focuses on the role that intelligent elements can play in ISHM architectures. We define an intelligent element as a smart element with sufficient computing capacity to support anomaly detection or other algorithms in support of ISHM functions. A smart element has the capabilities of supporting networked implementations of IEEE 1451.x smart sensor and actuator protocols. The ISHM group at SSC has been actively developing intelligent elements in conjunction with several partners at other Centers, universities, and companies as part of our ISHM approach for better supporting rocket engine testing. We have developed several implementations. Among the key features for these intelligent sensors is support for IEEE 1451.1 and incorporation of a suite of algorithms for determination of sensor health. Regardless of the potential advantages that can be achieved using intelligent sensors, existing large-scale systems are still based on conventional sensors and data acquisition systems. In order to bring the benefits of intelligent sensors to these environments, we have also developed virtual implementations of intelligent sensors.

  14. No! ... Not another Periodic Chart of the Elements!

    NASA Astrophysics Data System (ADS)

    Hefferlin, Ray

    1999-11-01

    No, but we present important evidence for Hakala's (Hakala, J. Chem. Phys. 56, 178 (1952)) chart, which differs from standard charts in having the s elements moved upwards to periods 0 through 6. First: All periods are doubled, including length 2. Second: Secondary periodicity(D.V. Korol'kov and V.A. Latysheva, Vestnik Sankt-Peterburgskovo Univesiteta, 1998, series 4, no. 1, pg. 52) is arranged so as to occur in the same periods rather than staggered. (Secondary periodicity is seen, for example, in the differences of the atomic numbers of elements and of the elements above them.) Third and most important: This form of the periodic chart can be derived from first principles(Y.B. Rumer and A.I. Fet, Teor. Mat. Fiz. (Russ) 9, 203 (1971))(A.O. Barut, in "Structure of Matter (Proceedings of the Rutherford Cantennary Symposium, 1971)," ed. B. Wybourne, University of Canterbury Press, Canterbury, 1972, pp. 126-136)(G.V. Zhuvikin and R. Hefferlin, Symmetry Principles for Periodic Systems of Molecules, Joint Report #1, Physics Departments, Southern Adventist University and St. Petersburg University, 1994) using the boson dynamical groups of symmetry SO(4,2)XSU(2)sXSU(2)d and subgroups.

  15. arXiv:0911.0938v2[math.RA]4Sep2011 GROUP ACTIONS ON ALGEBRAS AND THE GRADED LIE

    E-print Network

    Shepler, Anne

    Poisson structure integrates, i.e., lifts to a deformation (e.g., see Kontsevich [13]). Hal- bout and Tang is a Gerstenhaber algebra under two operations, a cup product and a graded Lie (Gerstenhaber) bracket. In [19], we examined the cohomology HH q (S(V )#G) as a graded algebra under cup product. In this paper, we study its

  16. Iron and s-elements abundance variations in NGC 5286: comparison with `anomalous' globular clusters and Milky Way satellites

    NASA Astrophysics Data System (ADS)

    Marino, A. F.; Milone, A. P.; Karakas, A. I.; Casagrande, L.; Yong, D.; Shingles, L.; Da Costa, G.; Norris, J. E.; Stetson, P. B.; Lind, K.; Asplund, M.; Collet, R.; Jerjen, H.; Sbordone, L.; Aparicio, A.; Cassisi, S.

    2015-06-01

    We present a high-resolution spectroscopic analysis of 62 red giants in the Milky Way globular cluster (GC) NGC 5286. We have determined abundances of representative light proton-capture, ?, Fe-peak and neutron-capture element groups, and combined them with photometry of multiple sequences observed along the colour-magnitude diagram. Our principal results are: (i) a broad, bimodal distribution in s-process element abundance ratios, with two main groups, the s-poor and s-rich groups; (ii) substantial star-to-star Fe variations, with the s-rich stars having higher Fe, e.g. < [Fe/H]> _{s-rich}} - < [Fe/H]> _{s-poor}} ˜ 0.2 dex; and (iii) the presence of O-Na-Al (anti)correlations in both stellar groups. We have defined a new photometric index, cBVI = (B - V) - (V - I), to maximize the separation in the colour-magnitude diagram between the two stellar groups with different Fe and s-element content, and this index is not significantly affected by variations in light elements (such as the O-Na anticorrelation). The variations in the overall metallicity present in NGC 5286 add this object to the class of anomalous GCs. Furthermore, the chemical abundance pattern of NGC 5286 resembles that observed in some of the anomalous GCs, e.g. M 22, NGC 1851, M 2, and the more extreme ? Centauri, that also show internal variations in s-elements, and in light elements within stars with different Fe and s-elements content. In view of the common variations in s-elements, we propose the term s-Fe-anomalous GCs to describe this sub-class of objects. The similarities in chemical abundance ratios between these objects strongly suggest similar formation and evolution histories, possibly associated with an origin in tidally disrupted dwarf satellites.

  17. Semi-empirical and empirical L X-ray production cross sections for elements with 50 ? Z ? 92 for protons of 0.5 3.0 MeV

    NASA Astrophysics Data System (ADS)

    Nekab, M.; Kahoul, A.

    2006-04-01

    We present in this contribution, semi-empirical production cross sections of the main X-ray lines L?, L? and L? for elements from Sn to U and for protons with energies varying from 0.5 to 3.0 MeV. The theoretical X-ray production cross sections are firstly calculated from the theoretical ionization cross sections of the L i ( i = 1, 2, 3) subshell within the ECPSSR theory. The semi-empirical L?, L? and L? cross sections are then deduced by fitting the available experimental data normalized to their corresponding theoretical values and give the better representation of the experimental data in some cases. On the other hand, the experimental data are directly fitted to deduce the empirical L X-ray production cross sections. A comparison is made between the semi-empirical cross sections, the empirical cross sections reported in this work and the empirical ones reported by Reis and Jesus [M.A. Reis, A.P. Jesus, Atom. Data Nucl. Data Tables 63 (1996) 1] and those of Strivay and Weber [Strivay, G. Weber, Nucl. Instr. and Meth. B 190 (2002) 112].

  18. Search for Standard Model Higgs Boson Production in Association with a W Boson Using a Matrix Element Technique at CDF in p-bar{p} Collisions at sqrt{s} = 1.96 TeV

    E-print Network

    CDF Collaboration; T. Aaltonen; B. Alvarez Gonzalez; S. Amerio; D. Amidei; A. Anastassov; A. Annovi; J. Antos; G. Apollinari; J. A. Appel; A. Apresyan; T. Arisawa; A. Artikov; J. Asaadi; W. Ashmanskas; B. Auerbach; A. Aurisano; F. Azfar; W. Badgett; A. Barbaro-Galtieri; V. E. Barnes; B. A. Barnett; P. Barria; P. Bartos; M. Bauce; G. Bauer; F. Bedeschi; D. Beecher; S. Behari; G. Bellettini; J. Bellinger; D. Benjamin; A. Beretvas; A. Bhatti; M. Binkley; D. Bisello; I. Bizjak; K. R. Bland; B. Blumenfeld; A. Bocci; A. Bodek; D. Bortoletto; J. Boudreau; A. Boveia; L. Brigliadori; A. Brisuda; C. Bromberg; E. Brucken; M. Bucciantonio; J. Budagov; H. S. Budd; S. Budd; K. Burkett; G. Busetto; P. Bussey; A. Buzatu; C. Calancha; S. Camarda; M. Campanelli; M. Campbell; F. Canelli; B. Carls; D. Carlsmith; R. Carosi; S. Carrillo; S. Carron; B. Casal; M. Casarsa; A. Castro; P. Catastini; D. Cauz; V. Cavaliere; M. Cavalli-Sforza; A. Cerri; L. Cerrito; Y. C. Chen; M. Chertok; G. Chiarelli; G. Chlachidze; F. Chlebana; K. Cho; D. Chokheli; J. P. Chou; W. H. Chung; Y. S. Chung; C. I. Ciobanu; M. A. Ciocci; A. Clark; C. Clarke; C. Coibanu; G. Compostella; M. E. Convery; J. Conway; M. Corbo; M. Cordelli; C. A. Cox; D. J. Cox; F. Crescioli; C. Cuenca Almenar; J. Cuevas; R. Culbertson; D. Dagenhart; N. d'Ascenzo; M. Datta; P. de Barbaro; S. De Cecco; G. De Lorenzo; M. Dell'Orso; C. Deluca; L. Demortier; J. Deng; M. Deninno; F. Devoto; M. d'Errico; A. Di Canto; B. Di Ruzza; J. R. Dittmann; M. D'Onofrio; S. Donati; P. Dong; M. Dorigo; T. Dorigo; K. Ebina; A. Elagin; A. Eppig; R. Erbacher; D. Errede; S. Errede; N. Ershaidat; R. Eusebi; H. C. Fang; S. Farrington; M. Feindt; J. P. Fernandez; C. Ferrazza; R. Field; G. Flanagan; R. Forrest; M. J. Frank; M. Franklin; J. C. Freeman; Y. Funakoshi; I. Furic; M. Gallinaro; J. Galyardt; J. E. Garcia; A. F. Garfinkel; P. Garosi; H. Gerberich; E. Gerchtein; S. Giagu; V. Giakoumopoulou; P. Giannetti; K. Gibson; C. M. Ginsburg; N. Giokaris; P. Giromini; M. Giunta; G. Giurgiu; V. Glagolev; D. Glenzinski; M. Gold; D. Goldin; N. Goldschmidt; A. Golossanov; G. Gomez; G. Gomez-Ceballos; M. Goncharov; O. Gonzalez; I. Gorelov; A. T. Goshaw; K. Goulianos; S. Grinstein; C. Grosso-Pilcher; R. C. Group; J. Guimaraes da Costa; Z. Gunay-Unalan; C. Haber; S. R. Hahn; E. Halkiadakis; A. Hamaguchi; J. Y. Han; F. Happacher; K. Hara; D. Hare; M. Hare; R. F. Harr; K. Hatakeyama; C. Hays; M. Heck; J. Heinrich; M. Herndon; S. Hewamanage; D. Hidas; A. Hocker; W. Hopkins; D. Horn; S. Hou; R. E. Hughes; M. Hurwitz; U. Husemann; N. Hussain; M. Hussein; J. Huston; G. Introzzi; M. Iori; A. Ivanov; E. James; D. Jang; B. Jayatilaka; E. J. Jeon; M. K. Jha; S. Jindariani; W. Johnson; M. Jones; K. K. Joo; S. Y. Jun; T. R. Junk; T. Kamon; P. E. Karchin; A. Kasmi; Y. Kato; W. Ketchum; J. Keung; V. Khotilovich; B. Kilminster; D. H. Kim; H. S. Kim; H. W. Kim; J. E. Kim; M. J. Kim; S. B. Kim; S. H. Kim; Y. K. Kim; N. Kimura; M. Kirby; S. Klimenko; K. Kondo; D. J. Kong; J. Konigsberg; A. V. Kotwal; M. Kreps; J. Kroll; D. Krop; N. Krumnack; M. Kruse; V. Krutelyov; T. Kuhr; M. Kurata; S. Kwang; A. T. Laasanen; S. Lami; S. Lammel; M. Lancaster; R. L. Lander; K. Lannon; A. Lath; G. Latino; T. LeCompte; E. Lee; H. S. Lee; J. S. Lee; S. W. Lee; S. Leo; S. Leone; J. D. Lewis; A. Limosani; C. -J. Lin; J. Linacre; M. Lindgren; E. Lipeles; A. Lister; D. O. Litvintsev; C. Liu; Q. Liu; T. Liu; S. Lockwitz; A. Loginov; D. Lucchesi; J. Lueck; P. Lujan; P. Lukens; G. Lungu; J. Lys; R. Lysak; R. Madrak; K. Maeshima; K. Makhoul; S. Malik; G. Manca; A. Manousakis-Katsikakis; F. Margaroli; C. Marino; M. Martinez; R. Martinez-Ballarin; P. Mastrandrea; M. E. Mattson; P. Mazzanti; K. S. McFarland; P. McIntyre; R. McNulty; A. Mehta; P. Mehtala; A. Menzione; C. Mesropian; T. Miao; D. Mietlicki; A. Mitra; H. Miyake; S. Moed; N. Moggi; M. N. Mondragon; C. S. Moon; R. Moore; M. J. Morello; J. Morlock; P. Movilla Fernandez; A. Mukherjee; Th. Muller; P. Murat; M. Mussini; J. Nachtman; Y. Nagai; J. Naganoma; I. Nakano; A. Napier; J. Nett; C. Neu; M. S. Neubauer; J. Nielsen; L. Nodulman; O. Norniella; E. Nurse; L. Oakes; S. H. Oh; Y. D. Oh; I. Oksuzian; T. Okusawa; R. Orava; L. Ortolan; S. Pagan Griso; C. Pagliarone; E. Palencia; V. Papadimitriou; A. A. Paramonov; J. Patrick; G. Pauletta; M. Paulini; C. Paus; D. E. Pellett; A. Penzo; T. J. Phillips; G. Piacentino; E. Pianori; J. Pilot; K. Pitts; C. Plager; L. Pondrom; S. Poprocki; K. Potamianos; O. Poukhov; F. Prokoshin; A. Pronko; F. Ptohos; E. Pueschel; G. Punzi; J. Pursley; A. Rahaman; V. Ramakrishnan; N. Ranjan; I. Redondo; P. Renton; M. Rescigno; T. Riddick; F. Rimondi; L. Ristori; A. Robson; T. Rodrigo; T. Rodriguez; E. Rogers; S. Rolli; R. Roser; M. Rossi; F. Rubbo; F. Ruffini; A. Ruiz; J. Russ; V. Rusu; A. Safonov; W. K. Sakumoto; Y. Sakurai; L. Santi; L. Sartori; K. Sato; V. Saveliev

    2012-04-18

    This paper presents a search for standard model Higgs boson production in association with a $W$ boson using events recorded by the CDF experiment in a dataset corresponding to an integrated luminosity of 5.6 fb-1. The search is performed using a matrix element technique in which the signal and background hypotheses are used to create a powerful discriminator. The discriminant output distributions for signal and background are fit to the observed events using a binned likelihood approach to search for the Higgs boson signal. We find no evidence for a Higgs boson, and 95% confidence level (C.L.) upper limits are set on the Higgs boson production rate. The observed limits range from 3.5 to 37.6 relative to the standard model expectation for Higgs boson masses between 100 and 150 GeV. The 95% C.L. expected limit is estimated from the median of an ensemble of simulated experiments and varies between 2.9 and 32.7 relative to the production rate predicted by the standard model over the Higgs boson mass range studied.

  19. Platinum-group elements distribution and spinel composition in podiform chromitites and associated rocks from the upper mantle section of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco

    NASA Astrophysics Data System (ADS)

    Ahmed, Ahmed H.; Arai, Shoji; Abdel-Aziz, Yaser M.; Ikenne, Moha; Rahimi, Abdellatif

    2009-09-01

    The distribution of platinum-group elements (PGEs), together with spinel composition, of podiform chromitites and serpentinized peridotites were examined to elucidate the nature of the upper mantle of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco. The mantle section is dominated by harzburgite with less abundant dunite. Chromitite pods are also found as small lenses not exceeding a few meters in size. Almost all primary silicates have been altered, and chromian spinel is the only primary mineral that survived alteration. Chromian spinel of chromitites is less affected by hydrothermal alteration than that of mantle peridotites. All chromitite samples of the Bou Azzer ophiolite display a steep negative slope of PGE spidergrams, being enriched in Os, Ir and Ru, and extremely depleted in Pt and Pd. Harzburgites and dunites usually have intermediate to low PGE contents showing more or less unfractionated PGE patterns with conspicuous positive anomalies of Ru and Rh. Two types of magnetite veins in serpentinized peridotite, type I (fibrous) and type II (octahedral), have relatively low PGE contents, displaying a generally positive slope from Os to Pd in the former type, and positive slope from Os to Rh then negative from Rh to Pd in the latter type. These magnetite patterns demonstrate their early and late hydrothermal origin, respectively. Chromian spinel composition of chromitites, dunites and harzburgites reflects their highly depleted nature with little variations; the Cr# is, on average, 0.71, 0.68 and 0.71, respectively. The TiO 2 content is extremely low in chromian spinels, <0.10, of all rock types. The strong PGE fractionation of podiform chromitites and the high-Cr, low-Ti character of spinel of all rock types imply that the chromitites of the Bou Azzer ophiolite were formed either from a high-degree partial melting of primitive mantle, or from melting of already depleted mantle peridotites. This kind of melting is most easily accomplished in the supra-subduction zone environment, indicating a genetic link with supra-subduction zone magma, such as high-Mg andesite or arc tholeiite. This is a general feature in the Neoproterozoic upper mantle.

  20. Identifying Elements in Supernova Remnants

    NSDL National Science Digital Library

    This activity has students use X-ray line data to identify elements contained in supernova remnants. In groups of 2 or more, they will be given several X-ray spectra from the ASCA X-ray satellite and will be asked to determine what elements are present, using a chart listing elements and the energies of their emission lines. Following a class discussion of their results, they will be given ASTRO-E spectra of the same sources and asked to determine which elements are present. Finally, they will be given spectra from Constellation-X and asked to determine what elements are present. Students will then compare and contrast Supernova Remnant Spectral Data from the three different X-ray observatories as a class. This site contains links to the simulated spectra, chart, student worksheet, and instructions.

  1. Adsorption of inert gases including element 118 on noble metal and inert surfaces from ab initio Dirac-Coulomb atomic calculations

    Microsoft Academic Search

    V. Pershina; A. Borschevsky; E. Eliav; U. Kaldor

    2008-01-01

    The interaction of the inert gases Rn and element 118 with various surfaces has been studied on the basis of fully relativistic ab initio Dirac-Coulomb CCSD(T) calculations of atomic properties. The calculated polarizability of element 118, 46.3 a.u., is the largest in group 18, the ionization potential is the lowest at 8.91 eV, and the estimated atomic radius is the

  2. Finite reflection groups q, t-Fu-Catalan numbers for real reflection groups

    E-print Network

    Faridi, Sara

    , UQAM #12;Finite reflection groups q, t-FuÃ?-Catalan numbers for real reflection groups Algebraic-FuÃ?-Catalan numbers for complex reflection groups #12;#12;Finite real reflection groups Let V be a finite-dimensional real vector space. A (finite) real reflection group W = t1, . . . , t O(V ) is a finite group

  3. An Electronically Tunable Reflectarray Using Varactor Diode-Tuned Elements

    E-print Network

    Hum, Sean Victor

    An Electronically Tunable Reflectarray Using Varactor Diode-Tuned Elements Sean V. Hum*tt Michal was loaded with a varactor diode [6]. Unfortunately only a 180" phase range was achieved with this element diodes [7]. Fixed reflectarray elements utilize changes in the electrical length of the patch element

  4. Una societ del Gruppo ABB An ABB Group company Sede Legale/ Registered Office: Capitale Sociale/Share Capital: 107.000.000.-i.v./fully paid up

    E-print Network

    Segatti, Antonio

    ABB S.p.A. Una società del Gruppo ABB An ABB Group company Sede Legale/ Registered Office: Capitale/VAT: IT11988960156 Codice Fiscale/Fiscal Code: 00736410150 Direzione e Uffici/ Headquarters and Offices, Process Automation, Discrete Automation and Motion. Ricerchiamo, per la divisione Power Systems che si

  5. Approximant of dodecagonal quasicrystal formed in Mn--Si--V alloy

    Microsoft Academic Search

    Hayato Iga; Marek Mihalkovic; Tsutomu Ishimasa

    2011-01-01

    The crystal structure of a hexagonal phase formed in Mn70Si20V10 has been analyzed by the Rietveld method using synchrotron radiation diffraction data. Analysis was carried out by assuming an average metallic element Mn0.875V0.125 via high resolution electron microscopy. The space group of the refined model is P6\\/mmm (No. 191) and the unit cell includes 18.9 Si and 78.1 metallic atoms.

  6. I. Novel methods to gallium nitride heterostructures via UHV-CVD and azidogallanes. II. Synthesis of related group IV and V covalent systems

    Microsoft Academic Search

    Jeffrey Allen McMurran

    1998-01-01

    The synthesis of new, potentially practical materials through novel molecular chemistry and ultrahigh vacuum chemical vapor deposition (UHV-CVD) is described. The method involves the synthesis of carefully designed, single-source inorganic precursors that incorporate the desired structure and\\/or stoichiometry of the target material. The nature of the precursors, no C--H or N--H bonds, and labile leaving groups, affords uncommonly low deposition

  7. Origin and Evolution of the Elements

    NASA Astrophysics Data System (ADS)

    McWilliam, Andrew; Rauch, Michael

    2004-09-01

    Introduction; List of participants; 1. Mount Wilson Observatory contributions to the study of cosmic abundances of the chemical elements George W. Preston; 2. Synthesis of the elements in stars: B2FH and beyond E. Margaret Burbidge; 3. Stellar nucleosynthesis: a status report 2003 David Arnett; 4. Advances in r-process nucleosynthesis John J. Cowan and Christopher Sneden; 5. Element yields of intermediate-mass stars Richard B. C. Henry; 6. The impact of rotation on chemical abundances in red giant branch stars Corinne Charbonnel; 7. s-processing in AGB stars and the composition of carbon stars Maurizio Busso, Oscar Straniero, Roberto Gallino, and Carlos Abia; 8. Models of chemical evolution Francesca Matteucci; 9. Model atmospheres and stellar abundance analysis Bengt Gustafsson; 10. The light elements: lithium, beryllium, and boron Ann Merchant Boesgaard; 11. Extremely metal-poor stars John E. Norris; 12. Thin and thick galactic disks Poul E. Nissen; 13. Globular clusters and halo field stars Christopher Sneden, Inese I. Ivans and Jon P. Fulbright; 14. Chemical evolution in ? Centauri Verne V. Smith; 15. Chemical composition of the Magellanic Clouds, from young to old stars Vanessa Hill; 16. Detailed composition of stars in dwarf spheroidal galaxies Matthew D. Shetrone; 17. The evolutionary history of Local Group irregular galaxies Eva K. Grebel; 18. Chemical evolution of the old stellar populations of M31 R. Michael Rich; 19. Stellar winds of hot massive stars nearby and beyond the Local Group Fabio Bresolin and Rolf P. Kudritzki; 20. Presolar stardust grains Donald D. Clayton and Larry R. Nittler; 21. Interstellar dust B. T. Draine; 22. Interstellar atomic abundances Edward B. Jenkins; 23. Molecules in the interstellar medium Tommy Wiklind; 24. Metal ejection by galactic winds Crystal L. Martin; 25. Abundances from the integrated light of globular clusters and galaxies Scott C. Trager; 26. Abundances in spiral and irregular galaxies Donald R. Garnett; 27. Chemical composition of the intracluster medium Michael Loewenstein; 28. Quasar elemental abundances and host galaxy evolution Fred Hamann, Matthias Dietrich, Bassem M. Sabra, and Craig Warner; 29. Chemical abundances in the damped Ly? systems Jason X. Prochaska; 30. Intergalactic medium abundances Robert F. Carswell; 31. Conference summary Bernard E. J. Pagel.

  8. Planets Around Low-Mass Stars (PALMS). V. Age-Dating Low-Mass Companions to Members and Interlopers of Young Moving Groups

    E-print Network

    Bowler, Brendan P; Liu, Michael C; Schlieder, Joshua E; Mann, Andrew W; Dupuy, Trent J; Hinkley, Sasha; Crepp, Justin R; Johnson, John Asher; Howard, Andrew W; Flagg, Laura; Weinberger, Alycia J; Aller, Kimberly M; Allers, Katelyn N; Best, William M J; Kotson, Michael C; Montet, Benjamin T; Herczeg, Gregory J; Baranec, Christoph; Riddle, Reed; Law, Nicholas M; Nielsen, Eric L; Wahhaj, Zahed; Biller, Beth A; Hayward, Thomas L

    2015-01-01

    We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7-M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8-120 Myr) in the literature. The inferred masses of the companions (~10-100 Mjup) are highly sensitive to the ages of the primary stars so we critically examine the kinematic and spectroscopic properties of each system to distinguish bona fide YMG members from old field interlopers. 2MASS J02155892-0929121 C is a new M7 substellar companion (40-60 Mjup) with clear spectroscopic signs of low gravity and hence youth. The primary, possibly a member of the ~40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (1 Gyr) tidally-locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with ...

  9. Mineral resource of the month: rare earth elements

    USGS Publications Warehouse

    U.S. Geological Survey

    2011-01-01

    The article provides information on rare earth elements, which are group of 17 natural metallic elements. The rare earth elements are scandium, yttrium and lanthanides and classified into light rare earth elements (LREE) and heavy rate earth elements (HREE). The principal ores of the rare earth elements are identified. An overview of China's production of 97 percent of the rare earths in the world is provided. Commercial applications of rare earths are described.

  10. The influence of combined magnesium and vanadate administration on the level of some elements in selected rat organs: V-Mg interactions and the role of iron-essential protein (DMT-1) in the mechanism underlying altered tissues iron level.

    PubMed

    Scibior, Agnieszka; Adamczyk, Agnieszka; Go??biowska, Dorota; Nied?wiecka, Irmina; Fornal, Emilia

    2014-04-01

    The effect of 12 week co-administration of sodium metavanadate (SMV) and magnesium sulfate (MS) on the levels of some elements in selected rats' organs and an attempt to elucidate a role of divalent metal transporter 1 (DMT-1) in the mechanism(s) of the SMV-induced disorders in some tissue Fe homeostasis were studied. SMV taken up separately or in combination with MS may pose a risk of the rise and shortage of the total hepatic and splenic Fe and Cu contents, respectively, cerebral Fe deficiency, splenic Ca deposition, and the hepatic, renal, and cerebral DMT-1 down-regulation. When administered alone, SMV may also cause the decrease in the total renal Fe and Cu contents. A visible protective effect of Mg against the renal and cerebral V accumulation and the decrease in the renal Fe and Cu contents during the SMV-MS co-administration together with our previous findings suggest a beneficial role of Mg at SMV exposure. Further, the SMV-induced fall in total iron binding capacity (TIBC), reported previously, and its correlations with the hepatic, splenic, and cerebral Fe levels allow us to suggest that diminished TIBC could be partly involved in the mechanism(s) responsible for the dramatic redistribution of Fe in those tissues. Finally, DMT-1, which potentially could participate in the hepatic non-transferrin Fe-bound uptake, does not play a significant role in this process indicating the need for studying other Fe transporters to more precisely elucidate molecular mechanism(s) underlying the hepatic Fe loading in our experimental conditions. PMID:24549458

  11. Structural and trace element changes in scalp hair of radiographers.

    PubMed

    Man, A C; Zheng, Y H; Mak, P K

    1998-07-01

    Scalp hair samples were collected from medical radiographers and nonradiographers of matching age groups. Structural morphology of hair was studied by scanning electron microscopy, and the trace element profiles in hair were measured using neutron activation analysis. The structural damage to the hair follicles of the radiographers was quite obvious, and this may be a good qualitative indicator of radiation damage at low doses. The concentrations of aluminum (Al), potassium (K), and vanadium (V) in hair of the radiographers were significantly higher, whereas those of antimony (Sb) and magnesium (Mg) were significantly lower than those of nonradiographers. Some of our findings were quite consistent with those of others in determining the changes in trace element concentrations in irradiated tissue. PMID:9764566

  12. Trace element recovery from coal preparation wastes

    Microsoft Academic Search

    R. C. Heaton; E. F. Thode; P. Wagner

    1982-01-01

    High-sulfur coal wastes from five preparation plants located in the eastern United States have been examined to determine their resource potentials. These wastes contain a number of elements (Al, S, Ti, V, Fe, Co, Mo) in quantities large enough so that, if recovered, a substantial fraction of the nation's needs could be satisfied. Several additional elements (Ni, Mg, Mn, Zn,

  13. A Novel Family of Short Interspersed Repetitive Elements (SINEs) from Cichlids: The Patterns of Insertion of SINEs at Orthologous Loci Support the Proposed Monophyly of Four Major Groups of Cichlid Fishes in Lake Tanganyika

    Microsoft Academic Search

    Kazuhiko Takahashi; Yohey Terai; Mutsumi Nishida; Norihiro Okada

    Short interspersed repetitive elements (SINEs) have been shown to be excellent markers of molecular phylogeny, since the integration of a SINE at a particular position in a genome can be considered an unambiguous derived homologous character. In the present study, we isolated a new family of SINEs from cichlids in Lake Tanganyika, whose speciation and diversification have been regarded as

  14. Trace elements in ocean ridge basalts

    NASA Technical Reports Server (NTRS)

    Kay, R. W.; Hubbard, N. J.

    1978-01-01

    A study is made of the trace elements found in ocean ridge basalts. General assumptions regarding melting behavior, trace element fractionation, and alteration effects are presented. Data on the trace elements are grouped according to refractory lithophile elements, refractory siderophile elements, and volatile metals. Variations in ocean ridge basalt chemistry are noted both for regional and temporal characteristics. Ocean ridge basalts are compared to other terrestrial basalts, such as those having La/Yb ratios greater than those of chondrites, and those having La/Yb ratios less than those of chondrites. It is found that (1) as compared to solar or chondrite ratios, ocean ridge basalts have low ratios of large, highly-charged elements to smaller less highly-charged elements, (2) ocean ridge basalts exhibit low ratios of volatile to nonvolatile elements, and (3) the transition metals Cr through Zn in ocean ridge basalts are not fractionated more than a factor of 2 or 3 from the chondritic abundance ratios.

  15. Planets Around Low-mass Stars (PALMS). V. Age-dating Low-mass Companions to Members and Interlopers of Young Moving Groups

    NASA Astrophysics Data System (ADS)

    Bowler, Brendan P.; Shkolnik, Evgenya L.; Liu, Michael C.; Schlieder, Joshua E.; Mann, Andrew W.; Dupuy, Trent J.; Hinkley, Sasha; Crepp, Justin R.; Johnson, John Asher; Howard, Andrew W.; Flagg, Laura; Weinberger, Alycia J.; Aller, Kimberly M.; Allers, Katelyn N.; Best, William M. J.; Kotson, Michael C.; Montet, Benjamin T.; Herczeg, Gregory J.; Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Nielsen, Eric L.; Wahhaj, Zahed; Biller, Beth A.; Hayward, Thomas L.

    2015-06-01

    We present optical and near-infrared adaptive optics (AO) imaging and spectroscopy of 13 ultracool (>M6) companions to late-type stars (K7–M4.5), most of which have recently been identified as candidate members of nearby young moving groups (YMGs; 8–120 Myr) in the literature. Three of these are new companions identified in our AO imaging survey, and two others are confirmed to be comoving with their host stars for the first time. The inferred masses of the companions (?10–100 MJup) are highly sensitive to the ages of the primary stars; therefore we critically examine the kinematic and spectroscopic properties of each system to distinguish bona fide YMG members from old field interlopers. The new M7 substellar companion 2MASS J02155892–0929121 C (40–60 MJup) shows clear spectroscopic signs of low gravity and, hence, youth. The primary, possibly a member of the ?40 Myr Tuc-Hor moving group, is visually resolved into three components, making it a young low-mass quadruple system in a compact (?100 AU) configuration. In addition, Li i ?6708 absorption in the intermediate-gravity M7.5 companion 2MASS J15594729+4403595 B provides unambiguous evidence that it is young (?200 Myr) and resides below the hydrogen-burning limit. Three new close-separation (<1?) companions (2MASS J06475229–2523304 B, PYC J11519+0731 B, and GJ 4378 Ab) orbit stars previously reported as candidate YMG members, but instead are likely old (?1 Gyr) tidally locked spectroscopic binaries without convincing kinematic associations with any known moving group. The high rate of false positives in the form of old active stars with YMG-like kinematics underscores the importance of radial velocity and parallax measurements to validate candidate young stars identified via proper motion and activity selection alone. Finally, we spectroscopically confirm the cool temperature and substellar nature of HD 23514 B, a recently discovered M8 benchmark brown dwarf orbiting the dustiest-known member of the Pleiades. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile (ESO Program 090.A-9010(A)).

  16. Trace element depth profiles in presolar silicon carbide grains

    NASA Astrophysics Data System (ADS)

    King, Ashley J.; Henkel, Torsten; Rost, Detlef; Lyon, Ian C.

    2012-10-01

    We have analyzed eleven presolar SiC grains from the Murchison meteorite using time-of-flight secondary ion mass spectrometry. The Si isotopic compositions of the grains indicate that they are probably of an AGB star origin. The average abundances of Mg, Fe, Ca, Al, Ti, and V are strongly influenced by their condensation behavior into SiC in circumstellar environments. Depth profiles of Li, B, Mg, Al, K, Ca, Ti, V, Cr, and Fe in the SiC grains show that trace elements are not always homogenously distributed. In approximately half of the SiC grains studied here, the trace element distributions can be explained by condensation processes around the grains' parent stars. These grains appear to have experienced only minimal processing before their arrival in the presolar molecular cloud, possibly due to short residence times in the interstellar medium. The remaining SiC grains contained elevated abundances of several elements within their outer 200 nm, which is attributed to the implantation of energetic ions accelerated by shockwaves in the interstellar medium. These grains may have spent a longer period of time in this region, hence increasing the probability of them passing through a shockfront. Distinct groups of presolar SiC grains whose residence times in the interstellar medium differ are consistent with previous findings based on noble gas studies, although some grains may also have been shielded from secondary alteration by protective outer mantles.

  17. Charged particle induced delayed X-rays (DEX) for the analysis of intermediate and heavy elements

    NASA Astrophysics Data System (ADS)

    Pillay, A. E.; Erasmus, C. S.; Andeweg, A. H.; Sellschop, J. P. F.; Annegarn, H. J.; Dunn, J.

    1988-12-01

    The emission of K X-rays from proton-rich and metastable radionuclides, following proton activation of the stable isotopes of the elements of interest, has not been widely used as a means of analysis. The thrust of this paper proposes a nuclear technique using delayed X-rays for the analysis of low concentrations of intermediate and heavy elements. The method is similar to the delayed gamma-ray technique. Proton bombardment induces mainly (p, n) reactions whereas the delayed X-rays originate largely from e --capture and isomeric transition. Samples of rare earth and platinum group elements (PGE), in the form of compacted powders, were irradiated with an 11 MeV proton beam and delayed X-rays detected with a 100 mm 2 Ge detector. Single element spectra for a range of rare earths and PGEs are presented. Analytical conditions are demonstrated for Pd in the range 0.1-5%. Spectra from actual geological samples of a PGE ore, preconcentrated by fire-assay, and monazite are presented. All six platinum group elements are visible and interference-free in a single spectrum, a marked advance on other nuclear techniques for these elements, including PIXE and neutron activation analysis (NAA).

  18. The use of organometallic group-V sources for the metalorganic molecular beam epitaxy growth of In 0.48Ga 0.52P/GaAs and In 0.53Ga 0.47As/InP heterojunction bipolar device structures

    NASA Astrophysics Data System (ADS)

    Beam, E. A.; Chau, H. F.; Henderson, T. S.; Liu, W.; Seabaugh, A. C.

    1994-03-01

    This paper describes the use of tertiarybutylarsine (TBA) and tertiarybutylphosphine (TBP) as replacements for arsine and phosphine in MOMBE/CBE for the production of device structures with state-of-the-art performance. The growth system used for this work is based on the use of elemental group-III and dopant sources, and employs thermal crackers for the low pressure precracking of TBA and TBP. Device structures fabricated in the In 0.48Ga 0.52P/GaAs materials system include single- and double-heterojunction bipolar transistors (SHBTs and DHBTs). Current gains as high as 2690 have been obtained with these transistors. Deep level transient spectroscopy (DLTS) measurements of the emitter-base junctions of these transistors reveals the absence of deep level traps, in contrast to similar devices fabricated using AlGaAs/GaAs. Device structures fabricated in the In 0.53Ga 0.47As/InP materials system include SHBTs, DHBTs, and resonant tunneling bipolar transistors (RTBTs). In 0.53Ga 0.47As/InP SHBTs with record maximum oscillation frequencies (ƒ max) of > 180 GHz have been produced with high breakdown voltages BV CEO and BV CBO of 8.1 and 17 V, respectively. In addition, DHBTs with ƒ T=134 GHz and ƒ max=137 GHz have been fabricated. Resonant tunneling bipolar transistors, consisting of a structured AlAs/In xGa 1- xAs resonant tunneling double barrier vertically integrated into the emitter of an InP/InGaAs double heterojunction bipolar transistor structure, have been demonstrated. These transistors have room temperature peak-to-valley current ratio of approximately 20, current gain of 100, and breakdown voltage exceeding 5 V, allowing the demonstration of the first room temperature resonant tunneling transistor integrated circuits.

  19. The anatomy of ?'/? beyond leading logarithms with improved hadronic matrix elements

    NASA Astrophysics Data System (ADS)

    Buras, Andrzej J.; Jamin, Matthias; Lautenbacher, Markus E.

    1993-11-01

    We use the recently calculated two-loop anomalous dimensions of current-current operators, QCD and electroweak penguin operators to construct the effective hamiltonian for ?S = 1 transitions beyond the leading logarithmic approximation. We solve the renormalization-group equations involving ?s and ? up to two-loop level and we give the numerical values of Wilson coefficient functions Ci( ?) beyond the leading logarithmic approximation in various renormalization schemes. Numerical results for the Wilson coefficients in ?B = 1 and ?C = 1 hamiltonians are also given. We discuss several aspects of renormalization scheme dependence and demonstrate the scheme independence of physical quantities. We stress that the scheme dependence of the Wilson coefficients Ci( ?) can only be cancelled by the one present in the hadronic matrix elements < Qi( ?)>. This requires also the calculation of O(?) corrections to < Qi( ?)>. We propose a new semi-phenomenological approach to hadronic matrix elements which incorporates the data for CP-conserving K ? ?? amplitudes and allows to determine the matrix elements of all ( V - A) ? ( V - A) operators in any renormalization scheme. Our renormalization-group analysis of all hadronic matrix elements < Qi( ?)> reveals certain interesting features. We compare critically our treatment of these matrix elements with those given in the literature. When matrix elements of dominant QCD penguin ( Q6) and electroweak penguin ( Q8) operators are kept fixed the effect of next-to-leading order corrections is to lower considerably ?'/? in the 't Hooft-Veltman (HV) renormalization scheme with a smaller effect in the dimensional regularization scheme with anticommuting ? 5 (NDR). Taking m t = 130 GeV, ? overlineMS = 300 MeV and calculating < Q6> and < Q8> in the 1/ N approach with ms(1 GeV) = 175 MeV, we find in the NDR scheme ?' ? = (6.7 ± 2.6) × 10 -4 in agreement with the experimental findings of E731. We point out however that the increase of < Q6> by only a factor of two gives ?'/ ? = (20.0 ± 6.5) × 10 -4 in agreement with the result of NA31. The dependence of ?'/? on ? overlineMS, m t and is presented. A detailed anatomy of various contributions and comparison with the analyses of Rome and Dortmund groups are given.

  20. Groups32

    NSDL National Science Digital Library

    A group theory calculator. Groups32 computes information about groups of orders 1-32; has a permutation group package; and provides a search for groups with given generators and relations. Site includes documentation as well as course handouts in PDF format.

  1. Proactive Groups.

    ERIC Educational Resources Information Center

    Galassi, John P., Ed.

    Several authors describe group counseling programs provided by a university counseling center to meet student needs for developing interpersonal communication skills and self-assertion behavior. In response to these needs, the counseling center provided personal growth groups, a proactive black group, a women's group, a marriage growth group, and…

  2. Probing adenine rings and backbone linkages using base specific isotope-edited Raman spectroscopy: application to group II intron ribozyme domain V.

    PubMed

    Chen, Yuanyuan; Eldho, Nadukkudy V; Dayie, T Kwaku; Carey, Paul R

    2010-04-27

    Raman difference spectroscopy is used to probe the properties of a 36-nt RNA molecule, "D5", which lies at the heart of the catalytic apparatus in group II introns. For D5 that has all of its adenine residues labeled with (13)C and (15)N and utilizing Raman difference spectroscopy, we identify the conformationally sensitive -C-O-P-O-C- stretching modes of the unlabeled bonds adjacent to adenine bases, as well as the adenine ring modes themselves. The phosphodiester modes can be assigned to individual adenine residues based on earlier NMR data. The effect of Mg(2+) binding was explored by analyzing the Raman difference spectra for [D5 + Mg(2+)] minus [D5 no Mg(2+)], for D5 unlabeled, or D5 labeled with (13)C/(15)N-enriched adenine. In both sets of data we assign differential features to G ring modes perturbed by Mg(2+) binding at the N7 position. In the A-labeled spectra we attribute a Raman differential near 1450 cm(-1) and changes of intensity at 1296 cm(-1) to Mg binding at the N7 position of adenine bases. The A and G bases involved in Mg(2+) binding again can be identified using earlier NMR results. For the unlabeled D5, a change in the C-O-P-O-C stretch profile at 811 cm(-1) upon magnesium binding is due to a "tightening up" (in the sense of a more rigid molecule with less dynamic interchange among competing ribose conformers) of the D5 structure. For adenine-labeled D5, small changes in the adenine backbone bond signatures in the 810-830 cm(-1) region suggest that small conformational changes occur in the tetraloop and bulge regions upon binding of Mg(2+). The PO(2)(-) stretching vibration, near 1100 cm(-1), from the nonbridging phosphate groups, probes the effect of Mg(2+)-hydrate inner-sphere interactions that cause an upshift. In turn, the upshift is modulated by the presence of monovalent cations since in the presence of Na(+) and Li(+) the upshift is 23 +/- 2 cm(-1) while in the presence of K(+) and Cs(+) it is 13 +/- 3 cm(-1), a finding that correlates with the differences in hydration radii. These subtle differences in electrostatic interactions may be related to observed variations in catalytic activity. For a reconstructed ribozyme comprising domains 1-3 (D123) connected in cis plus domain 5 (D5) supplied in trans, cleavage of spliced exon substrates in the presence of magnesium and K(+) or Cs(+) is more efficient than that in the presence of magnesium with Na(+) or Li(+). PMID:20225830

  3. Probing Adenine Rings and Backbone Linkages Using Base Specific Isotope-Edited Raman Spectroscopy: Application to Group II Intron Ribozyme Domain V†

    PubMed Central

    Chen, Yuanyuan; Eldho, Nadukkudy V.

    2010-01-01

    Raman difference spectroscopy is used to probe the properties of a 36-nt RNA molecule, “D5”, which lies at the heart of the catalytic apparatus in group II introns. For D5 that has all its adenine residues labeled with 13C and 15N, and utilizing Raman difference spectroscopy, we identify the conformational sensitive -C-O-P-O-C- stretching modes of the unlabeled bonds adjacent to adenine bases, as well as the adenine ring modes themselves. The phosphodiester modes can be assigned to individual adenine residues based on earlier NMR data. The effect of Mg2+ binding was explored by analyzing the Raman difference spectra for [D5 + Mg2+] minus [D5 no Mg2+], for D5 unlabeled, or D5 labeled with 13C/15N-enriched adenine. In both sets of data we assign differential features to G ring modes perturbed by Mg2+ binding at the N7 position. In the A labeled spectra we attribute a Raman differential near 1450 cm?1 and changes of intensity at 1296 cm?1 to Mg binding at the N7 position of adenine bases. The A and G bases involved in Mg2+ binding again can be identified using earlier NMR results. For the unlabeled D5, a change in the C-O-P-O-C stretch profile at 811 cm?1 upon magnesium binding is due to a “tightening up” (in the sense of a more rigid molecule with less dynamic interchange among competing ribose conformers) of the D5 structure. For adenine labeled D5, small changes in the adenine backbone bond signatures in the 810 – 830 cm?1 region suggest small conformational changes occur in the tetraloop and bulge regions upon binding of Mg2+. The PO2? stretching vibration, near 1100 cm?1, from the non-bridging phosphate groups, probes the effect of Mg2+-hydrate inner-sphere interactions that cause an up-shift. In turn, the up-shift is modulated by the presence of monovalent cations since in the presence of Na+ and Li+ the up-shift is (23±2 cm?1) while in the presence of K+ and Cs+ it is (13±3 cm?1), a finding that correlates with the differences in hydration radii. These subtle differences in electrostatic interactions may be related to observed variations in catalytic activity. For a reconstructed ribozyme comprising domains 1–3 (D123) connected in cis plus domain 5 (D5) supplied in trans, cleavage of spliced exon substrates in the presence of magnesium and K+ or Cs+ is more efficient than that in the presence of magnesium with Na+ or Li+. PMID:20225830

  4. Vanadium—An Essential Element for Animals and Humans?

    Microsoft Academic Search

    H. Illing-Günther; H. Gürtler; S. Holzinger; M. Jaritz; S. Anke; U. Schäfer

    According to the present level of knowledge and a given essentiality of this ultratrace element, V deficiency in flora, fauna and man need not be reckoned with in practice. It seems that there is no danger of a V overload via foodstuffs in Central Europe. However, the V emissions due to burning V-rich fossile fuels must be taken into consideration

  5. The Unusual 23S rRNA Gene of Coxiella burnetii: Two Self-Splicing Group I Introns Flank a 34-Base-Pair Exon, and One Element Lacks the Canonical  G

    Microsoft Academic Search

    Rahul Raghavan; Scott R. Miller; Linda D. Hicks; Michael F. Minnick

    2007-01-01

    We describe the presence and characteristics of two self-splicing group I introns in the sole 23S rRNA gene of Coxiella burnetii. The two group I introns, Cbu.L1917 and Cbu.L1951, are inserted at sites 1917 and 1951 (Escherichia coli numbering), respectively, in the 23S rRNA gene of C. burnetii. Both introns were found to be self-splicing in vivo and in vitro

  6. Modular conformal scaling group evidenced in lepton-quark mass

    NASA Astrophysics Data System (ADS)

    Rosen, Gerald

    1995-09-01

    Lepton-quark mass may reflect a correspondence in spacetime structure described by a modular conformal scaling group. Stemming in part from a spacetime line element correspondence ds ? (exp ? n) ds in which the eight quantities ? 0, ? 1, ..., ? 7 constitute a closed set under a modular addition, the associated formula for lepton-quark mass (yielding values at the 1 GeV scale for the leptons and lighter quarks and at the physical pole for the top) is conjectured to be m=m fQ2(exp - ? n), where m f=10.245 TeV is the progenitor fermion mass, Q is the charge number of the lepton or quark, and the modular group parameter ? n is indexed by a fermion principal quantum number n that depends on three mutually independent projection operators.

  7. Seed Laser Chirping for Enhanced Backward Raman Amplification in Plasmas Z. Toroker, V. M. Malkin, and N. J. Fisch

    E-print Network

    Seed Laser Chirping for Enhanced Backward Raman Amplification in Plasmas Z. Toroker, V. M. Malkin is that, by chirping the seed pulse, the group velocity dispersion may in fact be used advantageously elements will likely have to be replaced by plasma. In a plasma, a short counter-propagating seed pulse

  8. arXiv:0803.0234v1[math.GR]3Mar2008 CUTTING SEQUENCES AND PALINDROMES

    E-print Network

    arXiv:0803.0234v1[math.GR]3Mar2008 CUTTING SEQUENCES AND PALINDROMES JANE GILMAN AND LINDA KEEN- rems about primitive elements and palindromes in free groups of rank 2. The geometric treatment gives a pair of primitive associates. Definition 2. A word W = W(A, B) G is a palindrome if it reads the same

  9. On Finite Groups and Finite Fields.

    ERIC Educational Resources Information Center

    Reid, J. D.

    1991-01-01

    Given a multiplicative group of nonzero elements with order n, the explicit relationship between the number of cyclic subgroups of order d, which divides n, is used in the proof concerning the cyclic nature of that given multiplicative group. (JJK)

  10. Rare-Earth and Transuranic Elements

    Microsoft Academic Search

    M. Goeppert Mayer

    1941-01-01

    The possible existence of a second rare-earth-like group of elements beginning with uranium and extending to the transuranic elements, is discussed by a calculation of the atomic eigen-functions of the 4f and 5f electrons. Energy and spatial extension of the 4f eigenfunctions drop suddenly at the beginning of the rare-earth group; the binding energy is calculated to be 0.95 ev

  11. Acquisition chain elements Conditioner

    E-print Network

    Ravelet, Florent

    Acquisition chain elements Sensor Conditioner Data acquisition and transfer Applications Signal: an introduction #12;Acquisition chain elements Sensor Conditioner Data acquisition and transfer Applications Outline 1 Acquisition chain elements 2 Sensor Different signals and sensors Characteristics of sensors 3

  12. Sortable Elements for Quivers with Cycles

    E-print Network

    Reading, Nathan

    2009-01-01

    Each Coxeter element c of a Coxeter group W defines a subset of W called the c-sortable elements. The choice of a Coxeter element of W is equivalent to the choice of an acyclic orientation of the Coxeter diagram of W. In this paper, we define a more general notion of Omega-sortable elements, where Omega is an arbitrary orientation of the diagram, and show that the key properties of c-sortable elements carry over to the Omega-sortable elements. The proofs of these properties rely on reduction to the acyclic case, but the reductions are nontrivial; in particular, the proofs rely on a subtle combinatorial property of the weak order, as it relates to orientations of the Coxeter diagram. The c-sortable elements are closely tied to the combinatorics of cluster algebras with an acyclic seed; the ultimate motivation behind this paper is to extend this connection beyond the acyclic case.

  13. Summary Report of Working Group 2: Computation

    NASA Astrophysics Data System (ADS)

    Stoltz, P. H.; Tsung, R. S.

    2009-01-01

    The working group on computation addressed three physics areas: (i) plasma-based accelerators (laser-driven and beam-driven), (ii) high gradient structure-based accelerators, and (iii) electron beam sources and transport [1]. Highlights of the talks in these areas included new models of breakdown on the microscopic scale, new three-dimensional multipacting calculations with both finite difference and finite element codes, and detailed comparisons of new electron gun models with standard models such as PARMELA. The group also addressed two areas of advances in computation: (i) new algorithms, including simulation in a Lorentz-boosted frame that can reduce computation time orders of magnitude, and (ii) new hardware architectures, like graphics processing units and Cell processors that promise dramatic increases in computing power. Highlights of the talks in these areas included results from the first large-scale parallel finite element particle-in-cell code (PIC), many order-of-magnitude speedup of, and details of porting the VPIC code to the Roadrunner supercomputer. The working group featured two plenary talks, one by Brian Albright of Los Alamos National Laboratory on the performance of the VPIC code on the Roadrunner supercomputer, and one by David Bruhwiler of Tech-X Corporation on recent advances in computation for advanced accelerators. Highlights of the talk by Albright included the first one trillion particle simulations, a sustained performance of 0.3 petaflops, and an eight times speedup of science calculations, including back-scatter in laser-plasma interaction. Highlights of the talk by Bruhwiler included simulations of 10 GeV accelerator laser wakefield stages including external injection, new developments in electromagnetic simulations of electron guns using finite difference and finite element approaches.

  14. Food Groups

    MedlinePLUS

    Welcome to the Five Food Groups MyPlate illustrates the five food groups that are the building blocks for a healthy diet using a familiar image – ... half your grains whole. >> See Grains Group Protein Foods Go lean with protein. >> See Protein Foods Group ...

  15. Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Anderson, W. J.

    1983-01-01

    Rolling element bearings are a precision, yet simple, machine element of great utility. A brief history of rolling element bearings is reviewed and the type of rolling element bearings, their geometry and kinematics, as well as the materials they are made from and the manufacturing processes they involve are described. Unloaded and unlubricated rolling element bearings, loaded but unlubricated rolling element bearings and loaded and lubricated rolling element bearings are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element bearings.

  16. Order computations in generic groups

    E-print Network

    Sutherland, Andrew V

    2007-01-01

    We consider the problem of computing the order of an element in a generic group. The two standard algorithms, Pollard's rho method and Shanks' baby-steps giant-steps technique, both use [theta](N^1/2) group operations to ...

  17. Discrete Element Modeling

    SciTech Connect

    Morris, J; Johnson, S

    2007-12-03

    The Distinct Element Method (also frequently referred to as the Discrete Element Method) (DEM) is a Lagrangian numerical technique where the computational domain consists of discrete solid elements which interact via compliant contacts. This can be contrasted with Finite Element Methods where the computational domain is assumed to represent a continuum (although many modern implementations of the FEM can accommodate some Distinct Element capabilities). Often the terms Discrete Element Method and Distinct Element Method are used interchangeably in the literature, although Cundall and Hart (1992) suggested that Discrete Element Methods should be a more inclusive term covering Distinct Element Methods, Displacement Discontinuity Analysis and Modal Methods. In this work, DEM specifically refers to the Distinct Element Method, where the discrete elements interact via compliant contacts, in contrast with Displacement Discontinuity Analysis where the contacts are rigid and all compliance is taken up by the adjacent intact material.

  18. Characterization of tetra, dodeca and tetradeca Mo V polyoxometalate wheels structured by etidronate ligands

    Microsoft Academic Search

    Jean-Daniel Compain; Anne Dolbecq; Jérôme Marrot; Pierre Mialane; Francis Sécheresse

    2010-01-01

    The reactivity of the [MoV2O4]2+ dinuclear unit with the [O3P(C(CH3)(OH))PO3]4? etidronate ligand has been investigated. Three complexes have been isolated and characterized by IR spectroscopy, elemental analysis and single crystal X-Ray diffraction studies. Structural determination of the tetranuclear compound (CN3H6)6[(MoV2O4)2(O3P(C(CH3)O)PO3)2]·12H2O (1) revealed that the hydroxo group of the etidronate ligand can be deprotonated in presence of MoV even in acidic

  19. Contribution to the geochemistry of trace elements in the sediments of the Noun River and tributaries, western Cameroon.

    PubMed

    Njofang, C; Matschullat, J; Tchouankoué, J P; Amougou, A

    2007-09-15

    This study reports on the distribution of trace elements in the sediments of the Noun River valley. Two groups of trace elements have emerged based on their distribution and geochemical behaviour. The first group shows lower values whereas the second group aligns higher values. Elements like Al and Sr in one side and Zn, Zr in the other present concentrations statistically different from those of the rocks compared to other elements in trace analyzed (Cr, Ni, Ba, Co, Cu, Fe, Mn, V, As and Pb). The trace elements Al, Sr, Zr, Zn and Pb in the sediments of the Noun River show concentrations rather lower than those of the world. The average concentrations in elements C (3.72%), N (0.27%), S (0.05%) and of the ratios C/N (13.77) and N/S (5.29) reflect those resulting from the decomposition of the organic matter which derives from soils with very small concentrations in S. The Noun valley sediments are mostly of primary (quartz, microcline, plagioclase, orthoclase, ilmenite, anatase) and newly formed or secondary (kaolinite, gibbsite, hematite, goethite) minerals. This mineralogy and the overall low concentration of the studied trace elements, with Al, Fe, Ti and Mn as most abundant elements, is consistent with the local geology made up of the basic rocks (basalts, volcanic ash) and of the acid rocks (granites, gneiss). Overall the trace elements concentration and distribution suggest their geogene origin. Yet, this study is a first contribution of its kind towards the development of a baseline geochemical database essential for a sustainable and healthier Noun valley ecosystem. PMID:19090098

  20. Relativistic Dipole Matrix Element Zeros

    NASA Astrophysics Data System (ADS)

    Lajohn, L. A.; Pratt, R. H.

    2002-05-01

    There is a special class of relativistic high energy dipole matrix element zeros (RZ), whose positions with respect to photon energy ? , only depend on the bound state l quantum number according to ?^0=mc^2/(l_b+1) (independent of primary quantum number n, nuclear charge Z, central potential V and dipole retardation). These RZ only occur in (n,l_b,j_b)arrow (? , l_b+1,j_b) transitions such as ns_1/2arrow ? p_1/2; np_3/2arrow ? d_3/2: nd_5/2arrow ? f_5/2 etc. The nonrelativistic limit of these matrix elements can be established explicitly in the Coulomb case. Within the general matrix element formalism (such as that in [1]); when |? | is substituted for ? in analytic expressions for matrix elements, the zeros remain, but ?^0 now becomes dependent on n and Z. When the reduction to nonrelativistic form is completed by application of the low energy approximation ? mc^2 mc^2, the zeros disappear. This nonzero behavior was noted in nonrelativistic dipole Coulomb matrix elements by Fano and Cooper [2] and later proven by Oh and Pratt[3]. (J. H. Scofield, Phys. Rev. A 40), 3054 (1989 (U. Fano and J. W. Cooper, Rev. Mod. Phys. 40), 441 (1968). (D. Oh and R. H. Pratt, Phys. Rev. A 34), 2486 (1986); 37, 1524 (1988); 45, 1583 (1992).

  1. Trace elements in the human scalp hair and finger nails as affected by infection with Schistosoma mansoni

    NASA Astrophysics Data System (ADS)

    El-Khatib, Ahmed M.; Bahnassy, Ahmed A.; Denton, M.

    1995-01-01

    The concentration of 13 elements has been determined in finger nail and scalp hair of 4 groups representing normal and infected Schistosoma mansoni subjects. Samples were irradiated by thermal neutrons from a Triga Mark III Reactor, for 10 min. Measurements were made using a HPGe detector coupled with ADC and PDP {11}/{34} data processing equipment. The results showed significant increases of Al, Cl, I and Br in both finger nails and scalp hair of bilharzial patients above those of normal subjects while Mg, Ca, V, Mn, Cu, Sr, K, S and Na showed significant decreases. Most of the elements showed a higher concentration in finger nails than in hair.

  2. 41 CFR Appendix C to Chapter 301 - Standard Data Elements for Federal Travel [Traveler Identification

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Standard Data Elements for Federal Travel [Traveler Identification...C to Chapter 301—Standard Data Elements for Federal Travel [Traveler Identification] Group name Data elements Description Travel...

  3. 41 CFR Appendix C to Chapter 301 - Standard Data Elements for Federal Travel [Traveler Identification

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Standard Data Elements for Federal Travel [Traveler Identification...C to Chapter 301—Standard Data Elements for Federal Travel [Traveler Identification] Group name Data elements Description Travel...

  4. The Superheavy Elements and Anti-Gravity

    NASA Astrophysics Data System (ADS)

    Anastasovski, Petar K.

    2004-02-01

    The essence of any propulsion concept is to overcome gravity. Anti-gravity is a natural means to achieve this. Thus, the technology to pursue anti-gravity, by using superheavy elements, may provide a new propulsion paradigm. The theory of superluminal relativity provides a hypothesis for existence of elements with atomic number up to Z = 145, some of which may possess anti-gravity properties. Analysis results show that curved space-time exists demonstrating both gravitic and anti-gravitic properties not only around nuclei but inside the nuclei as well. Two groups of elements (Z < 64 and 63 < Z <145) exist that demonstrate these capabilities. The nuclei of the first group of elements have the masses with only the property of gravity. The nuclei of the elements of the second group have the masses with both properties: gravity and anti-gravity in two different ranges of curved space-time around the nuclei.. The hypothetical element with Z = 145 is the unique among all elements whose nucleus has only anti-gravity property. It is proposed that this element be named Hawking, in honour of Stephen W. Hawking.

  5. Distinguishing symmetric quantum oracles and quantum group multiplication

    E-print Network

    Orest Bucicovschi; Daniel Copeland; David A. Meyer; James Pommersheim

    2015-03-18

    Given a unitary representation of a finite group on a finite-dimensional Hilbert space, we show how to find a state whose translates under the group are distinguishable with the highest probability. We apply this to several quantum oracle problems, including the GROUP MULTIPLICATION problem, in which the product of an ordered $n$-tuple of group elements is to be determined by querying elements of the tuple. For any finite group $G$, we give an algorithm to find the product of two elements of $G$ with a single quantum query with probability $2/|G|$. This generalizes Deutsch's Algorithm from $Z_2$ to an arbitrary finite group. We further prove that this algorithm is optimal. We also introduce the HIDDEN CONJUGATING ELEMENT PROBLEM, in which the oracle acts by conjugating by an unknown element of the group. We show that for many groups, including dihedral and symmetric groups, the unknown element can be determined with probability $1$ using a single quantum query.

  6. Ion Microprobe Study of Plagioclase-Basalt Partition Experiments at Natural Concentration Levels of Trace Elements

    NASA Astrophysics Data System (ADS)

    Bindeman, Ilya N.; Davis, Andrew M.; Drake, Michael J.

    1998-04-01

    We present here a study of plagioclase/melt partitioning of trace elements at their natural concentration levels, using sample charges from the widely cited plagioclase/melt partitioning experiments of Drake and Weill (1975). In these experiments, sample charges were doped to ˜1 wt% with Sr, Ba, rare earth elements (REE) and Y, but each charge was only doped with one to four elements. Thus, these samples provide an opportunity to compare partition coefficients (D ?) at natural concentration levels with those for doped concentration levels for the same composition of plagioclase, melt and temperature. Plagioclase-glass pairs of seventeen runs at four different plagioclase compositions and temperatures were analyzed by electron microprobe for major elements and some of the doped trace elements and by ion microprobe for undoped Li, Be, B, F, Mg, P, Cl, K, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Rb, Sr, Y, Zr, Nb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, and Pb. Partitioning of the homovalent substituting ions Sr 2+ and Ba 2+ show no differences between doped and natural concentration levels. Ion microprobe measured D ? heterovalent substituting ions REE 3+ and Y 3+ at natural concentration levels (0.3-3 ppm) in samples doped with wt% levels of Sr or Ba are up to three times higher than at doped concentration levels and cannot be explained by analytical artifacts. We discuss possible reasons for this. All trace element D ? data show linear relationships of the forms ln (D ?) = a? X An + b? and RT ln (D ?) = a X An + b in 0.4 < X An < 0.8 range. Alkalies, alkaline earths, and lanthanides exhibit the same type of compositional dependence within each group of elements. Slopes a? and a vary with the increase of the ionic radius within each valence group. The smaller ions of each of these groups exhibit no or positive slopes a? and a; the larger ions show negative slopes. The magnitudes of the slopes increase linearly with ionic radii within the same valence group. This relationship allows extrapolation and prediction of the compositional dependence of elements of the same group whose concentrations could not be measured in this work. We present best fit approximation parameters for the RT ln (D ?) = a X An + b relationship. These can be used in various petrologic applications to reconstruct the primary trace elemental composition of the parental melt from which plagioclase crystallized.

  7. The Element Game

    NSDL National Science Digital Library

    Jefferson Lab

    2013-01-07

    The computer will randomly pick an element and present the student with that element's data from the Periodic Table of Elements. They will use that information to answer the question that the computer asks about the number of protons, neutrons, electrons or nucleons (particles in the nucleus) that an atom of that element contains.

  8. The Unfocused Focus Group: Benefit or Bane?

    ERIC Educational Resources Information Center

    Franz, Nancy K.

    2011-01-01

    Facilitating successful focus groups requires both science and art. One element that can fully challenge focus group facilitators includes how to handle the unfocused focus group. This article describes "unfocus" and the benefits and disadvantages of unfocus in focus groups. Lessons learned from and approaches taken on this journey are shared to…

  9. Theoretical predictions of properties and volatility of chlorides and oxychlorides of group-4 elements. II. Adsorption of tetrachlorides and oxydichlorides of Zr, Hf, and Rf on neutral and modified surfaces

    NASA Astrophysics Data System (ADS)

    Pershina, V.; Borschevsky, A.; Iliaš, M.; Türler, A.

    2014-08-01

    With the aim to interpret results of gas-phase chromatography experiments on volatility of group-4 tetrachlorides and oxychlorides including those of Rf, adsorption enthalpies of these species on neutral, and modified quartz surfaces were estimated on the basis of relativistic, two-component Density Functional Theory calculations of MCl4, MOCl2, MCl6-, and MOCl42 with the use of adsorption models. Several mechanisms of adsorption were considered. In the case of physisorption of MCl4, the trend in the adsorption energy in the group should be Zr > Hf > Rf, so that the volatility should change in the opposite direction. The latter trend complies with the one in the sublimation enthalpies, ?Hsub, of the Zr and Hf tetrachlorides, i.e., Zr < Hf. On the basis of a correlation between these quantities, ?Hsub(RfCl4) was predicted as 104.2 kJ/mol. The energy of physisorption of MOCl2 on quartz should increase in the group, Zr < Hf < Rf, as defined by increasing dipole moments of these molecules along the series. In the case of adsorption of MCl4 on quartz by chemical forces, formation of the MOCl2 or MOCl42- complexes on the surface can take place, so that the sequence in the adsorption energy should be Zr > Hf > Rf, as defined by the complex formation energies. In the case of adsorption of MCl4 on a chlorinated quartz surface, formation of the MCl62- surface complexes can occur, so that the trend in the adsorption strength should be Zr ? Hf < Rf. All the predicted sequences, showing a smooth change of the adsorption energy in the group, are in disagreement with the reversed trend Zr ? Rf < Hf, observed in the "one-atom-at-a-time" gas-phase chromatography experiments. Thus, currently no theoretical explanation can be found for the experimental observations.

  10. Super- and Hyperdeformed Isomeric States and Long-Lived Superheavy Elements

    E-print Network

    A. Marinov; S. Gelberg; D. Kolb; R. Brandt; R. V. Gentry; A. Pape

    2004-05-23

    The recent discoveries of the long-lived high spin super- and hyperdeformed isomeric states and their unusual radioactive decay properties are described. Based on their existence a consistent interpretation is given to the production of the long-lived superheavy element with Z = 112, via secondary reactions in CERN W targets, and to the low energy and very enhanced alpha-particle groups seen in various actinide fractions separated from the same W target. In addition, consistent interpretations are suggested for previously unexplained phenomena seen in nature. These are the Po halos, the low-energy enhanced 4.5 MeV alpha-particle group proposed to be due to an isotope of a superheavy element with Z = 108, and the giant halos.

  11. Factorizations in finite groups

    SciTech Connect

    Kulikov, Viktor S [Steklov Mathematical Institute, Russian Academy of Sciences, Moscow (Russian Federation)] [Steklov Mathematical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2013-02-28

    A necessary condition for uniqueness of factorizations of elements of a finite group G with factors belonging to a union of some conjugacy classes of G is given. This condition is sufficient if the number of factors belonging to each conjugacy class is big enough. The result is applied to the problem on the number of irreducible components of the Hurwitz space of degree d marked coverings of P{sup 1} with given Galois group G and fixed collection of local monodromies. Bibliography: 9 titles.

  12. Taxonomy Working Group Final Report

    NASA Technical Reports Server (NTRS)

    Parsons, Vickie S.; Beil, Robert J.; Terrone, Mark; Barth, Timothy S.; Panontin, Tina L.; Wales, Roxana; Rackley, Michael W.; Milne, James S.; McPherson, John W.; Dutra, Jayne E.; Shaw, Larry C.

    2009-01-01

    The purpose of the Taxonomy Working Group was to develop a proposal for a common taxonomy to be used by all NASA projects in the classifying of nonconformances, anomalies, and problems. Specifically, the group developed a recommended list of data elements along with general suggestions for the development of a problem reporting system to better serve NASA's need for managing, reporting, and trending project aberrant events. The Group's recommendations are reported in this document.

  13. Palindromic richness and Coxeter groups

    E-print Network

    Pelantová, Edita

    2011-01-01

    For a given finite group $G$ consisting of morphisms and antimorphisms of a free monoid $\\mathcal{A}^*$, we study infinite words with language closed under the group $G$. We focus on words rich in generalized palindromic factors, i.e., in factors $w$ satisfying $\\Theta(w) = w$ for some non-identical element $\\Theta \\in G$. We give several equivalent descriptions of rich words and show the role Coxeter groups play in the generalized notion of palindromic richness.

  14. Hot Groups.

    ERIC Educational Resources Information Center

    Vail, Kathleen

    1996-01-01

    Collaborators sparked by creative ideas and obsessed by a common task may not realize they're part of a "hot group"--a term coined by business professors Harold J. Leavitt and Jean Lipman-Blumen. Spawned by group decision making and employee empowerment, hot groups can flourish in education settings. They're typically small, short lived, and goal…

  15. Using laser micro mass spectrometry with the LAMMA-1000 instrument for monitoring relative elemental concentrations in vitrinite

    USGS Publications Warehouse

    Morelli, J.J.; Hercules, D.M.; Lyons, P.C.; Palmer, C.A.; Fletcher, J.D.

    1988-01-01

    The variation in relative elemental concentrations among a series of coal macerals belonging to the vitrinite maceral group was determined using laser micro mass spectrometry (LAMMS). Variations in Ba, Cr, Ga, Sr, Ti, and V concentrations among the coals were determined using the LAMM A-1000 instrument. LAMMS analysis is not limited to these elements; their selection illustrates the application of the technique. Ba, Cr, Ga, Sr, Ti, and V have minimal site-to-site variance in the vitrinite macerals of the studied coals as measured by LAMMS. The LAMMS data were compared with bulk elemental data obtained by instrumental neutron activation analysis (INAA) and D. C. arc optical emission spectroscopy (DCAS) in order to determine the reliability of the LAMMS data. The complex nature of the ionization phenomena in LAMMS and the lack of standards characterized on a microscale makes obtaining quantitative elemental data within the ionization microvolume difficult; however, we demonstrate that the relative variation of an element among vitrinites from different coal beds in the eastern United States can be observed using LAMMS in a "bulk" mode by accumulating signal intensities over several microareas of each vitrinite. Our studies indicate gross changes (greater than a factor of 2 to 5 depending on the element) can be monitored when the elemental concentration is significantly above the detection limit. "Bulk" mode analysis was conducted to evaluate the accuracy of future elemental LAMMS microanalyses. The primary advantage of LAMMS is the inherent spatial resolution, ~ 20 ??m for coal. Two different vitrite bands in the Lower Bakerstown coal bed (CLB-1) were analyzed. The analysis did not establish any certain concentration differences in Ba, Cr, Ga, Sr, Ti, and V between the two bands. ?? 1988 Springer-Verlag.

  16. Partitioning of platinum-group elements (PGE) and chalcogens (Se, Te, As, Sb, Bi) between monosulfide-solid solution (MSS), intermediate solid solution (ISS) and sulfide liquid at controlled fO2-fS2 conditions

    NASA Astrophysics Data System (ADS)

    Liu, Yanan; Brenan, James

    2015-06-01

    In order to better understand the behavior of highly siderophile elements (HSEs: Os, Ir, Ru, Rh, Pt, Pd, Au, Re), Ag, Pb and chalcogens (As, Se, Sb, Te and Bi) during the solidification of sulfide magmas, we have conducted a series of experiments to measure partition coefficients (D values) between monosulfide solid solution (MSS) and sulfide melt, as well as MSS and intermediate solid solution (ISS), at 0.1 MPa and 860-926 °C, log fS2 -3.0 to -2.2 (similar to the Pt-PtS buffer), with fO2 controlled at the fayalite-magnetite-quartz (FMQ) buffer. The IPGEs (Os, Ir, Ru), Rh and Re are found to be compatible in MSS relative to sulfide melt with D values ranging from ?20 to ?5, and DRe/DOs of ?0.5. Pd, Pt, Au, Ag, Pb, as well as the chalcogens, are incompatible in MSS, with D values ranging from ?0.1 to ?1 × 10-3. For the same metal/sulfur ratio, D values for the IPGEs, Rh and Re are systematically larger than most past studies, correlating with higher oxygen content in the sulfide liquid, reflecting the significant effect of oxygen on increasing the activity coefficients for these elements in the melt phase. MSS/ISS partitioning experiments reveal that Ru, Os, Ir, Rh and Re are partitioned into MSS by a factor of >50, whereas Pd, Pt, Ag, Au and the chalcogens partition from weakly (Se, As) to strongly (Ag, Au) into ISS. Uniformly low MSS- and ISS- melt partition coefficients for the chalcogens, Pt, Pd, Ag and Au will lead to enrichment in the residual sulfide liquid, but D values are generally too large to reach early saturation in Pt-Pd-chalcogen-rich accessory minerals, based on current solubility estimates. Instead, these phases likely precipitate at the last dregs of crystallization. Modeled evolution curves for the PGEs and chalcogens are in reasonably good agreement with whole-rock sulfide compositions for the McCreedy East deposit (Sudbury, Ontario), consistent with an origin by crystallization of MSS, then MSS + ISS from sulfide magma.

  17. Hope Medical Group for Women v. Edwards.

    PubMed

    1998-09-11

    The U.S. Court of Appeals for the Fifth Circuit invalidated a Louisiana law which restricted Medicaid reimbursement for abortion to instances where the pregnancy threatened the life of the mother. Although the revised 1994 Hyde Amendment permitted federal Medicaid funding for the abortion of pregnancies resulting from rape or incest, the Fifth Circuit held that the Hyde Amendment did not require states to fund these procedures. Instead, the court relied on the purposes of Medicaid to provide health-sustaining medical care and held that Louisiana's statute impermissibly restricted a women's right to abortion where medically necessary. Louisiana was enjoined from enforcing the law to the extent it restricted Medicaid reimbursement for the medically necessary abortion of pregnancies resulting from rape or incest. The court held that the state's interest in normal childbirth is not sufficient to sustain the abortion funding restriction. PMID:11648424

  18. Trace element analysis of ureilites: New constraints on their petrogenesis

    SciTech Connect

    Spitz, A.H.; Boynton, W.V. (Univ. of Arizona, Tuscon (United States))

    1991-11-01

    Six ureilites (ALHA77257, ALHA81101, ALH82130, PCA82506, Kanna, and Novo Urei) were analyzed using neutron activation analysis for Ca, Sc, Cr, Mn, Fe, Co, Ni, Zn, Ga, REE, W, Re, Os, Ir, and Au. The authors examined bulk samples as well as acid-treated samples. In bulk samples the refractory siderophiles' concentrations range from approximately 0.1 to 1.0 times CI chondrites while the volatile siderophiles' concentrations range from approximately 0.1 to 1.0 times CI chondrites while the volatile siderophiles range from about 0.07 to 0.3 times CI chondrites. Rare earth elements (REEs) in ureilites are quite depleted and display light and heavy rare earth enrichments. The Antarctic meteorites display either much less pronounced v-shaped patterns or no enrichment in the light rare earths at all. In terms of the new trace-element results, ureilites do not fall into the coherent groups that other workers have defined by chemical or petrographic characteristics. Trace elements do provide additional constraints on the models for the petrogenesis of ureilites. In particular, the siderophile element abundances call for simplified models of chemical processing rather than the complex, multistage processing called for in silicate fractionation models. REE concentrations, on the other hand, imply multistage processing to produce the ureilites. None of the ureilite petrogenesis models extant account for the trace element data. These new data and the considerations of them with respect to the proposed ureilite petrogenesis models indicate that the direction of modeling should be toward contemplation of mixtures and how the components the authors observe in ureilites behave under such conditions.

  19. Occurrence model for magmatic sulfide-rich nickel-copper-(platinum-group element) deposits related to mafic and ultramafic dike-sill complexes: Chapter I in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Schulz, Klaus J.; Woodruff, Laurel G.; Nicholson, Suzanne W.; Seal, Robert R., II; Piatak, Nadine M.; Chandler, Val W.; Mars, John L.

    2014-01-01

    The sulfides in magmatic Ni-Cu deposits generally constitute a small volume of the host rock(s) and tend to be concentrated in the lower parts of the mafic and/or ultramafic bodies, often in physical depressions or areas marking changes in the geometry of the footwall topography. In most deposits, the sulfide mineralization can be divided into disseminated, matrix or net, and massive sulfide, depending on a combination of the sulfide content of the rock and the silicate texture. The major Ni-Cu sulfide mineralogy typically consists of an intergrowth of pyrrhotite (Fe7S8), pentlandite ([Fe, Ni]9S8), and chalcopyrite (FeCuS2). Cobalt, PGE, and gold (Au) are extracted from most magmatic Ni-Cu ores as byproducts, although such elements can have a significant impact on the economics in some deposits, such as the Noril’sk-Talnakh deposits, which produce much of the world’s palladium. In addition, deposits may contain between 1 and 15 percent magnetite associated with the sulfides.

  20. How Deep and Hot was Earth's Magma Ocean? Combined Experimental Datasets for the Metal-Silicate Partitioning of 11 Siderophile Elements - Ni, Co, Mo, W, P, Mn, V, Cr, Ga, Cu and Pd

    Microsoft Academic Search

    K. Righter

    2008-01-01

    Since ~1990 high pressure and temperature (PT) experiments on metal-silicate systems have showed that partition coefficients (D) for siderophile (iron-loving) elements are much different than those measured at low PT conditions. The high PT data have been used to argue for a magma ocean during growth of the early Earth. Initial conclusions were based on experiments and calculations for a

  1. Homogeneous Grouping and Heterogeneous Grouping.

    ERIC Educational Resources Information Center

    Ediger, Marlow

    This paper discusses how to group students for reading instruction. The paper first considers the reasons for heterogeneous grouping, where there are mixed levels of reading achievement among the students in the classroom. It then discusses some weaknesses in advocating heterogeneous grouping. There are individualized plans for reading instruction…

  2. University of Amsterdam Programming Research Group

    E-print Network

    Amsterdam, Universiteit van

    .A. Bergstra, Y. Hirschfeld, and J.V. Tucker, Skew Meadows, Programming Research Group - University of Amsterdam, 2007. [PRG0705] J.A. Bergstra, Y. Hirschfeld, and J.V. Tucker, Meadows, Programming Research

  3. MBE growth technology for high quality strained III-V layers

    NASA Technical Reports Server (NTRS)

    Grunthaner, Frank J. (inventor); Liu, John K. (inventor); Hancock, Bruce R. (inventor)

    1990-01-01

    The III-V films are grown on large automatically perfect terraces of III-V substrates which have a different lattice constant, with temperature and Group III and V arrival rates chosen to give a Group III element stable surface. The growth is pulsed to inhibit Group III metal accumulation of low temperature, and to permit the film to relax to equilibrium. The method of the invention: (1) minimizes starting step density on sample surface; (2) deposits InAs and GaAs using an interrupted growth mode (0.25 to 2 monolayers at a time); (3) maintains the instantaneous surface stoichiometry during growth (As-stable for GaAs, In-stable for InAs); and (4) uses time-resolved RHEED to achieve aspects (1) through (3).

  4. MBE growth technology for high quality strained III-V layers

    NASA Technical Reports Server (NTRS)

    Grunthaner, Frank J. (Inventor); Liu, John K. (Inventor); Hancock, Bruce R. (Inventor)

    1992-01-01

    III-V films are grown on large automatically perfect terraces of III-V substrates which have a different lattice constant, with temperature and Group II and V arrival rates chosen to give a Group III element stable surface. The growth is pulsed to inhibit Group III metal accumulation to low temperature, and to permit the film to relax to equilibrium. The method of the invention 1) minimizes starting step density on sample surface; 2) deposits InAs and GaAs using an interrupted growth mode (0.25 to 2 mono-layers at a time); 3) maintains the instantaneous surface stoichiometry during growth (As-stable for GaAs, In-stable for InAs); and 4) uses time-resolved RHEED to achieve aspects (1)-14 (3).

  5. Chemistry of trace elements in soils and groundwater

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We present information about sources of processes that affect trace elements in soils and groundwater; precipitation and dissolution, surface interactions and absorption and oxidation-reduction reactions. For each element or group of elements, we provide a review of mode of occurrence, sources and ...

  6. Optimale Bedingungen der Atomabsorption, erläutert am periodischen System der Elemente

    Microsoft Academic Search

    H. A. v. Derschau; H. Prugger

    1969-01-01

    The 42 most important elements which can be determined by atomic absorption were examined according to a common method in order to establish the most favourable working conditions. The elements of groups IB and IIA and IIB were determined with the highest sensitivity at the lowest possible current of the hollow cathode lamp. All other elements yielded optimum results at

  7. In vitro characterization of the splicing efficiency and fidelity of the RmInt1 group II intron as a means of controlling the dispersion of its host mobile element

    PubMed Central

    Chillón, Isabel; Molina-Sánchez, María Dolores; Fedorova, Olga; García-Rodríguez, Fernando Manuel; Martínez-Abarca, Francisco

    2014-01-01

    Group II introns are catalytic RNAs that are excised from their precursors in a protein-dependent manner in vivo. Certain group II introns can also react in a protein-independent manner under nonphysiological conditions in vitro. The efficiency and fidelity of the splicing reaction is crucial, to guarantee the correct formation and expression of the protein-coding mRNA. RmInt1 is an efficient mobile intron found within the ISRm2011-2 insertion sequence in the symbiotic bacterium Sinorhizobium meliloti. The RmInt1 intron self-splices in vitro, but this reaction generates side products due to a predicted cryptic IBS1* sequence within the 3? exon. We engineered an RmInt1 intron lacking the cryptic IBS1* sequence, which improved the fidelity of the splicing reaction. However, atypical circular forms of similar electrophoretic mobility to the lariat intron were nevertheless observed. We analyzed a run of four cytidine residues at the 3? splice site potentially responsible for a lack of fidelity at this site leading to the formation of circular intron forms. We showed that mutations of residues base-pairing in the tertiary EBS3–IBS3 interaction increased the efficiency and fidelity of the splicing reaction. Our results indicate that RmInt1 has developed strategies for decreasing its splicing efficiency and fidelity. RmInt1 makes use of unproductive splicing reactions to limit the transposition of the insertion sequence into which it inserts itself in its natural context, thereby preventing potentially harmful dispersion of ISRm2011-2 throughout the genome of its host. PMID:25336586

  8. In vitro characterization of the splicing efficiency and fidelity of the RmInt1 group II intron as a means of controlling the dispersion of its host mobile element.

    PubMed

    Chillón, Isabel; Molina-Sánchez, María Dolores; Fedorova, Olga; García-Rodríguez, Fernando Manuel; Martínez-Abarca, Francisco; Toro, Nicolás

    2014-12-01

    Group II introns are catalytic RNAs that are excised from their precursors in a protein-dependent manner in vivo. Certain group II introns can also react in a protein-independent manner under nonphysiological conditions in vitro. The efficiency and fidelity of the splicing reaction is crucial, to guarantee the correct formation and expression of the protein-coding mRNA. RmInt1 is an efficient mobile intron found within the ISRm2011-2 insertion sequence in the symbiotic bacterium Sinorhizobium meliloti. The RmInt1 intron self-splices in vitro, but this reaction generates side products due to a predicted cryptic IBS1* sequence within the 3' exon. We engineered an RmInt1 intron lacking the cryptic IBS1* sequence, which improved the fidelity of the splicing reaction. However, atypical circular forms of similar electrophoretic mobility to the lariat intron were nevertheless observed. We analyzed a run of four cytidine residues at the 3' splice site potentially responsible for a lack of fidelity at this site leading to the formation of circular intron forms. We showed that mutations of residues base-pairing in the tertiary EBS3-IBS3 interaction increased the efficiency and fidelity of the splicing reaction. Our results indicate that RmInt1 has developed strategies for decreasing its splicing efficiency and fidelity. RmInt1 makes use of unproductive splicing reactions to limit the transposition of the insertion sequence into which it inserts itself in its natural context, thereby preventing potentially harmful dispersion of ISRm2011-2 throughout the genome of its host. PMID:25336586

  9. Vesta's Elemental Composition

    NASA Technical Reports Server (NTRS)

    Prettyman, T. H.; Beck, A. W.; Feldman, W. C.; Lawrence, D. J.; McCoy, T. J.; McSween, H. Y.; Mittlefehldt, D. W.; Peplowski, P. N.; Raymond, C. A.; Reedy, R. C.; Russell, C. T.; Titus, T. N.; Toplis, M. J.; Yamashita, N.

    2014-01-01

    Many lines of evidence (e.g. common geochemistry, chronology, O-isotope trends, and the presence of different HED rock types in polymict breccias) indicate that the howardite, eucrite, and diogenite (HED) meteorites originated from a single parent body. Meteorite studies show that this protoplanet underwent igneous differentiation to form a metallic core, an ultramafic mantle, and a basaltic crust. A spectroscopic match between the HEDs and 4 Vesta along with a plausible mechanism for their transfer to Earth, perhaps as chips off V-type asteroids ejected from Vesta's southern impact basin, supports the consensus view that many of these achondritic meteorites are samples of Vesta's crust and upper mantle. The HED-Vesta connection was put to the test by the NASA Dawn mission, which spent a year in close proximity to Vesta. Measurements by Dawn's three instruments, redundant Framing Cameras (FC), a Visible-InfraRed (VIR) spectrometer, and a Gamma Ray and Neutron Detector (GRaND), along with radio science have strengthened the link. Gravity measurements by Dawn are consistent with a differentiated, silicate body, with a dense Fe-rich core. The range of pyroxene compositions determined by VIR overlaps that of the howardites. Elemental abundances determined by nuclear spectroscopy are also consistent with HED-compositions. Observations by GRaND provided a new view of Vesta inaccessible by telescopic observations. Here, we summarize the results of Dawn's geochemical investigation of Vesta and their implications.

  10. Colliding Groups

    Microsoft Academic Search

    Steven Murray

    2001-01-01

    ACIS-I observations of the X-ray groups around NGC6868 and NGC6861 will allow us to investigate the possible merger of these groups into a larger system. Both groups have extended, symmetric X-ray emission, centered on the bright NGC galaxies. Both have been extensively studied at other wavelengths. Of note, NGC6868 has a central radio source and studies of the stellar and

  11. Adsorption of superheavy elements on metal surfaces.

    PubMed

    Sarpe-Tudoran, C; Fricke, B; Anton, J; Persina, V

    2007-05-01

    Fully relativistic four-component density functional theory with the general gradient approximation calculations have been performed to determine the adsorption energy and position of the superheavy element 112 on a Au surface. Extended cluster as well as embedded cluster calculations were used to simulate the surface which allow for the top, bridge, and hollow adsorption sites without losing the advantage of symmetry considerations. Comparison with analogous calculations of the adsorption of the homologue element Hg allows to predict the adsorption of element 112 at a bridge site with a binding energy of 0.67 eV. PMID:17492874

  12. Superheavy elements and r-process

    SciTech Connect

    Panov, I. V., E-mail: Igor.Panov@itep.ru; Korneev, I. Yu. [Institute of Theoretical and Experimental Physics (Russian Federation); Thielemann, F.-K. [Institut fuer Physik der Universitaet Basel (Switzerland)

    2009-06-15

    The probability for the production of superheavy elements in the astrophysical r-process is discussed. The dependence of the estimated superheavy-element yields on input data is estimated. Preliminary calculations revealed that the superheavy-element yields at the instant of completion of the r-process may be commensurate with the uranium yield, but the former depend strongly on the models used to forecast the properties of beta-delayed, neutron-induced, and spontaneous fission. This study is dedicated to the 80th anniversary of V.S. Imshennik's birth.

  13. Adopt an Element Project

    NSDL National Science Digital Library

    Mrs. Sleasman

    2009-11-20

    There are 2 requirements for this project. The first requirement is the completion of your Adopt an Element Research Sheet which accounts for 25% of your overall grade. The second requirement is the creation of a brochure, poster, or PowerPoint presentation advertising your element and accounts for 75% of your overall grade. Today you will be using your time in the media center to research your assigned element. In the space below you will find a list of websites followed by a description of what information the site will provide. Simply click on these different links to begin researching your element. (You are not limited to these websites but I suggest you focus your search here) Make sure that as you are researching your element you are also recording your information on your Adopt an Element Research Sheet. The information on this sheet is what you will need to have on the final copy of your element fact sheet so make sure that it is completed in its entirety. Good luck and have fun investigating your elements! http://elements.wlonk.com/ElementUses.htm : A good site for quick descriptions of your element. Also lists many uses of the element with links to more information. www.chemicalelements.com/index.html : Basic information about the elements and their uses as well as information about how they were discovered and when. Also has information on the origin of ...

  14. Concentration of stable elements in food products

    SciTech Connect

    Montford, M.A.; Shank, K.E.; Hendricks, C.; Oakes, T.W.

    1980-01-01

    Food samples were taken from commercial markets and analyzed for stable element content. The concentrations of most stable elements (Ag, Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, La, Mg, Mn, Mo, Na, Rb, Sb, Sc, Se, Sr, Ta, Th, Ti, V, Zn, Zr) were determined using multiple-element neutron activation analysis, while the concentrations of other elements (Cd, Hg, Ni, Pb) were determined using atomic absorption. The relevance of the concentrations found are noted in relation to other literature values. An earlier study was extended to include the determination of the concentration of stable elements in home-grown products in the vicinity of the Oak Ridge National Laboratory. Comparisons between the commercial and local food-stuff values are discussed.

  15. Fine and coarse elemental components in the urban aerosol of São Paulo, Brazil

    NASA Astrophysics Data System (ADS)

    Bouéres, Luiz Carlos S.; Orsini, Celso M. Q.

    1981-03-01

    Using cascade impactor sampling and PIXE analysis we have measured particle size distributions for approximately 15 elements in the São Paulo urban atmosphere. These elements, in our case, may be classified, according to their occurrence in fine or coarse aerosol log-normal modes, into three groups: (a) soil dust reference elements (coarse particle mode): Ti, Si and Ca; (b) anthropogenic fine particle mode: Zn, Br and Pb; and (c) mixed bimodal elements: S, K, V, Cr, Mn, Ni, Cu and Fe. All of the soil dust reference elements show consistently the log-normal parameters MMAD ? 5.5 ?m and ?g ? 3.2 (mass median aerodynamic diameter and geometric standard deviation, respectively). Enrichment factor calculations for Ti, Si, Ca and K in the coarse particle fraction (>2 ?mad), relative to Fe and the "standard crustal aerosol" values of Lawson and Winchester, show that Ti and Si are mainly soil derived while Ca and K may have significant industrial components in this particle fraction (i.e. coarse mode). The fine mode parameters for the other elements show variations with element suggesting different air pollution sources (such as motor vehicles, resuspended dust, refuse burning, industrial activities, etc.) and/or different chemical pathways, which presumably could be identifiable. For example, the modal parameters for group (b) are: Zn, MMAD=0.9 ?m ?g=2.2; Br, MMAD=0.5 ?m, ?g=4.0; Pb, MMAD=0.6 ?m, ?g=3.0; thus suggesting a common source (automotive) for Br and Pb, unrelated to the source of Zn (possibly refuse burning).

  16. On nth commutativity degree of some 3-Engel groups

    NASA Astrophysics Data System (ADS)

    Yahya, Zainab; Mohd Ali, Nor Muhainiah; Sarmin, Nor Haniza; Sabani, Muhammad Syafiq; Zakaria, Mardhiah

    2013-04-01

    This paper focuses on some 3-Engel groups. Suppose x and y are elements of a group G. The commutativity degree of a group is the probability that two elements in the group commute and is denoted by P(G). Meanwhile, the nth commutativity degree of a group G is the probability that for any pairs of x and y in G, xn and y commute. In this paper, the nth commutativity degree of some 3-Engel groups is determined.

  17. Superheavy element flerovium (element 114) is a volatile metal.

    PubMed

    Yakushev, Alexander; Gates, Jacklyn M; Türler, Andreas; Schädel, Matthias; Düllmann, Christoph E; Ackermann, Dieter; Andersson, Lise-Lotte; Block, Michael; Brüchle, Willy; Dvorak, Jan; Eberhardt, Klaus; Essel, Hans G; Even, Julia; Forsberg, Ulrika; Gorshkov, Alexander; Graeger, Reimar; Gregorich, Kenneth E; Hartmann, Willi; Herzberg, Rolf-Dietmar; Hessberger, Fritz P; Hild, Daniel; Hübner, Annett; Jäger, Egon; Khuyagbaatar, Jadambaa; Kindler, Birgit; Kratz, Jens V; Krier, Jörg; Kurz, Nikolaus; Lommel, Bettina; Niewisch, Lorenz J; Nitsche, Heino; Omtvedt, Jon Petter; Parr, Edward; Qin, Zhi; Rudolph, Dirk; Runke, Jörg; Schausten, Brigitta; Schimpf, Erwin; Semchenkov, Andrey; Steiner, Jutta; Thörle-Pospiech, Petra; Uusitalo, Juha; Wegrzecki, Maciej; Wiehl, Norbert

    2014-02-01

    The electron shell structure of superheavy elements, i.e., elements with atomic number Z ? 104, is influenced by strong relativistic effects caused by the high Z. Early atomic calculations on element 112 (copernicium, Cn) and element 114 (flerovium, Fl) having closed and quasi-closed electron shell configurations of 6d(10)7s(2) and 6d(10)7s(2)7p1/2(2), respectively, predicted them to be noble-gas-like due to very strong relativistic effects on the 7s and 7p1/2 valence orbitals. Recent fully relativistic calculations studying Cn and Fl in different environments suggest them to be less reactive compared to their lighter homologues in the groups, but still exhibiting a metallic character. Experimental gas-solid chromatography studies on Cn have, indeed, revealed a metal-metal bond formation with Au. In contrast to this, for Fl, the formation of a weak bond upon physisorption on a Au surface was inferred from first experiments. Here, we report on a gas-solid chromatography study of the adsorption of Fl on a Au surface. Fl was produced in the nuclear fusion reaction (244)Pu((48)Ca, 3-4n)(288,289)Fl and was isolated in-flight from the primary (48)Ca beam in a physical recoil separator. The adsorption behavior of Fl, its nuclear ?-decay product Cn, their lighter homologues in groups 14 and 12, i.e., Pb and Hg, and the noble gas Rn were studied simultaneously by isothermal gas chromatography and thermochromatography. Two Fl atoms were detected. They adsorbed on a Au surface at room temperature in the first, isothermal part, but not as readily as Pb and Hg. The observed adsorption behavior of Fl points to a higher inertness compared to its nearest homologue in the group, Pb. However, the measured lower limit for the adsorption enthalpy of Fl on a Au surface points to the formation of a metal-metal bond of Fl with Au. Fl is the least reactive element in the group, but still a metal. PMID:24456007

  18. Rock Groups

    NSDL National Science Digital Library

    Steven Strogatz

    2010-02-07

    In this one-page article Steven Strogatz explains how representing numbers with concrete objects can make calculations less confusing. By using images of rocks, he demystifies concepts such as square numbers, parity, primes, and sums of consecutive numbers. This is the second in Steven's series of 15 articles on the Elements of Math (home page cataloged separately).

  19. Adopt An Element

    NSDL National Science Digital Library

    Science Spot

    2011-12-01

    This can be used as a homework assignment or completed in the computer lab. Students will have to research information on one element and complete an advertisement for that element as if they were trying to market it.

  20. Trace Elements and Health

    ERIC Educational Resources Information Center

    Pettyjohn, Wayne A.

    1972-01-01

    Summarizes the effects of arsenic, lead, zinc, mercury, and cadmium on human health, indicates the sources of the elements in water, and considers the possibility of students in high schools analyzing water for trace amounts of the elements. (AL)