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1

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

NASA Astrophysics Data System (ADS)

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 but, compounds SiC, BN, AlP, and ZnSe are semiconductors. First row elements do not form zigzag structures.

Tongay, S.; Durgun, E.; Ciraci, S.

2004-12-01

2

Oxo-group-14-element bond formation in binuclear uranium(V) Pacman complexes.  

PubMed

Simple and versatile routes to the functionalization of uranyl-derived U(V)-oxo groups are presented. The oxo-lithiated, binuclear uranium(V)-oxo complexes [{(py)3LiOUO}2(L)] and [{(py)3LiOUO}(OUOSiMe3)(L)] were prepared by the direct combination of the uranyl(VI) silylamide "ate" complex [Li(py)2][(OUO)(N")3] (N" = N(SiMe3)2) with the polypyrrolic macrocycle H4L or the mononuclear uranyl (VI) Pacman complex [UO2(py)(H2L)], respectively. These oxo-metalated complexes display distinct U-O single and multiple bonding patterns and an axial/equatorial arrangement of oxo ligands. Their ready availability allows the direct functionalization of the uranyl oxo group leading to the binuclear uranium(V) oxo-stannylated complexes [{(R3Sn)OUO}2(L)] (R = nBu, Ph), which represent rare examples of mixed uranium/tin complexes. Also, uranium-oxo-group exchange occurred in reactions with [TiCl(OiPr)3] to form U-O-C bonds [{(py)3LiOUO}(OUOiPr)(L)] and [(iPrOUO)2(L)]. Overall, these represent the first family of uranium(V) complexes that are oxo-functionalised by Group 14 elements. PMID:23794441

Jones, Guy M; Arnold, Polly L; Love, Jason B

2013-07-29

3

Strain driven topological phase transitions in atomically thin films of group IV and V elements in the honeycomb structures  

NASA Astrophysics Data System (ADS)

We have investigated topological electronic properties of freestanding bilayers of group IV (C, Si, Ge, Sn, and, Pb) and V (As, Sb, and, Bi) elements of the periodic table in the buckled and planar honeycomb structures under isotropic strain using first-principles calculations. Our focus is on mapping strain driven phase diagrams and identifying topological phase transitions therein as a pathway for guiding search for suitable substrates to grow two-dimensional (2D) topological insulators (TIs) films. Bilayers of group IV elements, excepting Pb, generally transform from trivial metal \\to topological metal \\to TI \\to topological metal \\to trivial metal phase with increasing strain from negative (compressive) to positive (tensile) values. Similarly, among the group V elements, As and Sb bilayers transform from trivial metal \\to trivial insulator \\to TI phase, while Bi transforms from a topological metal to TI phase. The band gap of 0.5 eV in the TI phase of Bi is the largest we found among all bilayers studied, with the band gap increasing further under tensile strain. Differences in the topological characteristics of bilayers of group V elements reflect associated differences in the strength of the spin–orbit coupling (SOC). We show, in particular, that the topological band structure of Sb bilayer becomes similar to that of a Bi bilayer when the strength of the SOC in Sb is artificially enhanced by a factor of 4. This study provides the first report that As can be a 2D TI under tensile strain. Notably, we found the existence of TI phases in all elemental bilayers we studied, except Pb.

Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Liu, Yu-Tzu; Lin, Hsin; Su, Wan-Sheng; Ozolins, Vidvuds; Bansil, Arun

2014-10-01

4

Platinum-group element geochemistry of the Zhuqing Fe-Ti-V oxide ore-bearing mafic intrusions in western Yangtze Block, SW China: control of platinum-group elements by magnetite  

NASA Astrophysics Data System (ADS)

Platinum-group element (PGE) geochemistry combined with elemental geochemistry and magnetite compositions are reported for the Mesoproterozoic Zhuqing Fe-Ti-V oxide ore-bearing mafic intrusions in the western Yangtze Block, SW China. All the Zhuqing gabbros display extremely low concentrations of chalcophile elements and PGEs. The oxide-rich gabbros contain relatively higher contents of Cr, Ni, Ir, Ru, Rh, and lower contents of Pt and Pd than the oxide-poor gabbros. The abundances of whole-rock concentrations of Ni, Ir, Ru, and Rh correlate well with V contents in the Zhuqing gabbros, implying that the distributions of these elements are controlled by magnetite. The fractionation between Ir-Ru-Rh and Pt-Pd in the Zhuqing gabbros is mainly attributed to fractional crystallization of chromite and magnetite, whereas Ru anomalies are mainly due to variable degrees of compatibility of PGE in magnetite. The order of relative incompatibility of PGEs is calculated to be Pd < Pt < Rh < Ir < Ru. The very low PGE contents and Cu/Zr ratios and high Cu/Pd ratios suggest initially S-saturated magma parents that were highly depleted in PGE, which mainly formed due to low degrees of partial melting leaving sulfides concentrating PGEs behind in the mantle. Moreover, the low MgO, Ni, Ir and Ru contents and high Cu/Ni and Pd/Ir ratios for the gabbros suggest a highly evolved parental magma. Fe-Ti oxides fractionally crystallized from the highly evolved magma and subsequently settled in the lower sections of the magma chamber, where they concentrated and formed Fe-Ti-V oxide ore layers at the base of the lower and upper cycles. Multiple episodes of magma replenishment in the magma chamber may have been involved in the formation of the Zhuqing intrusions.

Fan, Hong-Peng; Zhu, Wei-Guang; Zhong, Hong; Bai, Zhong-Jie; He, De-Feng; Ye, Xian-Tao; Chen, Cai-Jie; Cao, Chong-Yong

2014-06-01

5

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

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.

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

6

Properties of Group Five and Group Seven transactinium elements  

SciTech Connect

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.

Wilk, Philip A.

2001-05-01

7

Colloidal nanocrystals of lithiated group?14 elements.  

PubMed

The synthesis of colloidal nanocrystals (NCs) of lithiated group?14 elements (Z=Si, Ge, and Sn) is reported, which are Li4.4 Si, Li3.75 Si, Li4.4 Ge, and Li4.4 Sn. Lix Z compounds are highly reactive and cannot be synthesized by existing methods. The success relied on separating the surface protection from the crystal formation and using a unique passivating ligand. Bare Lix Z crystals were first produced by milling elemental Li and Z in an argon-filled jar. Then, under the assistance of additional milling, hexyllithium was added to passivate the freshly generated Lix Z NCs. This ball-milling-assisted surface protection method may be generalized to similar systems, such as Nax Z and Kx Z. Moreover, Li4.4 Si and Li4.4 Ge NCs were conformally encapsulated in carbon fibers, providing great opportunities for studying the potential of using Lix Z to mitigate the volume-fluctuation-induced poor cyclability problem confronted by Z?anodes in lithium-ion batteries. PMID:25367697

Cloud, Jacqueline E; Wang, Yonglong; Yoder, Tara S; Taylor, Lauren W; Yang, Yongan

2014-12-22

8

How to efficiently select an arbitrary Clifford group element  

NASA Astrophysics Data System (ADS)

We give an algorithm which produces a unique element of the Clifford group on n qubits ( C n ) from an integer 0 ? i < |C n| (the number of elements in the group). The algorithm involves O(n 3) operations and provides, in addition to a canonical mapping from the integers to group elements g, a factorization of g into a sequence of at most 4n symplectic transvections. The algorithm can be used to efficiently select random elements of C n which are often useful in quantum information theory and quantum computation. We also give an algorithm for the inverse map, indexing a group element in time O(n 3).

Koenig, Robert; Smolin, John A.

2014-12-01

9

Sudoplatov S. V. ON GENERIC GROUP TRIGONOMETRIES  

E-print Network

Sudoplatov S. V. ON GENERIC GROUP TRIGONOMETRIES The positive solution of known problem pseudo- planes [3]. A demanded generic trigonometry trmgen can be constructed from arbi- trary everywhere finitely defined group trigonometry [4] in the limit step of chain of the following operations: 1) a free

Sudoplatov, Sergey Vladimirovich

10

Potential Mobilization of Platinum-Group Elements by  

E-print Network

-group elements (PGEs) from catalytic converters has led to increased environmental abundances of Pt, Pd, and Rh. Introduction The release of the platinum-group elements (PGEs) Pd, Pt, and Rh from catalytic converters is well released by catalytic converters, refs 9, 10) with the synthetic sidero- phore desferrioxamine-B (DFO

11

Calculation of elements of spin groups using generalized Pauli's theorem  

E-print Network

We formulate generalizations of Pauli's theorem on the cases of real and complex Clifford algebras of even and odd dimensions. We give analogues of these theorems in matrix formalism. Using these theorems we present an algorithm for computing elements of spin groups that correspond to elements of orthogonal groups as double cover.

D. S. Shirokov

2014-09-08

12

How to efficiently select an arbitrary Clifford group element  

E-print Network

We give an algorithm which produces a unique element of the Clifford group C_n on n qubits from an integer 0\\le i elements in the group). The algorithm involves O(n^3) operations. It is a variant of the subgroup algorithm by Diaconis and Shahshahani which is commonly applied to compact Lie groups. We provide an adaption for the symplectic group Sp(2n,F_2) which provides, in addition to a canonical mapping from the integers to group elements g, a factorization of g into a sequence of at most 4n symplectic transvections. The algorithm can be used to efficiently select randomelements of C_n which is often useful in quantum information theory and quantum computation. We also give an algorithm for the inverse map, indexing a group element in time O(n^3).

Robert Koenig; John A. Smolin

2014-06-09

13

Parallel and Serial Grouping of Image Elements in Visual Perception  

ERIC Educational Resources Information Center

The visual system groups image elements that belong to an object and segregates them from other objects and the background. Important cues for this grouping process are the Gestalt criteria, and most theories propose that these are applied in parallel across the visual scene. Here, we find that Gestalt grouping can indeed occur in parallel in some…

Houtkamp, Roos; Roelfsema, Pieter R.

2010-01-01

14

Methods for forming group III-V arsenide-nitride semiconductor materials  

NASA Technical Reports Server (NTRS)

Methods are disclosed for forming Group III--arsenide-nitride semiconductor materials. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

2000-01-01

15

Platinum group elements in the environment and their health risk  

Microsoft Academic Search

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

Khaiwal Ravindra; László Bencs; René Van Grieken

2004-01-01

16

Doubly bonded systems between heavier Group 15 elements.  

PubMed

There has been much interest in the synthesis and properties of doubly bonded systems between heavier Group 15 elements, i. e. heavier analogues of azo-compounds (dipnictenes), from the viewpoints of fundamental and material chemistry. Although such double-bond compounds between heavier main group elements are known to be highly reactive, too much so to be isolated as stable compounds, a number of reports on the synthesis of kinetically stabilized diphosphenes (RP[double bond, length as m-dash]PR), diarsenes (RAs[double bond, length as m-dash]AsR), and phosphaarsenes (RP[double bond, length as m-dash]AsR) bearing bulky substituent have been published since 1980. We have also succeeded in the synthesis of the first stable distibene (RSb[double bond, length as m-dash]SbR) and dibismuthene (RBi[double bond, length as m-dash]BiR) by taking advantage of efficient steric protection groups, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) and 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt), and revealed their structures and properties systematically. Thus, the doubly bonded compounds between heavier Group 15 elements are no longer imaginary species but are those with real existence which are stable, even in the case of the heaviest non-radioactive element bismuth, when they are appropriately protected by bulky substituents. This Perspective describes our research on the chemistry of kinetically stabilized double-bond compounds between heavier Group 15 elements. PMID:18322615

Sasamori, Takahiro; Tokitoh, Norihiro

2008-03-21

17

Symmetries of KdV and Loop Groups Jeremy Schi  

E-print Network

Symmetries of KdV and Loop Groups Jeremy Schi Department of Mathematics and Computer Science Bar of the Segal-Wilson map from the SL(2; C) loop group to a class of solutions of the KdV hierarchy is given transformations, of KdV arise from simple, eld independent, ac- tions on the loop group. A variety of issues

Schiff, Jeremy

18

arXiv:astro-ph/0409552v122Sep2004 Neutron-Capture Element Abundances in Halo Stars  

E-print Network

arXiv:astro-ph/0409552v122Sep2004 Neutron-Capture Element Abundances in Halo Stars John J. Cowan Telescope (HST) detections of the elements Ge, Zr and Pt in a group of 11 halo stars. Correla- tions between these elements and Eu (obtained with ground-based observations), and with respect to metallicity, are also

Cowan, John

19

Chemical evolution of heavy elements in the Local Group  

NASA Astrophysics Data System (ADS)

Only recently, the incredible progress made by telescopes in the past few years has opened the door to the detailed study of the chemical abundances in the stars belonging to the Local Group, if we exclude the solar vicinity. Thanks to this progress, the Local Group has become a natural benchmark for the chemical evolution models; the different chemical enrichments shown in the stars belonging to the different systems forming the Local Group, can be used to check the validity of the theoretical nucleosynthesis yields. We show our results for the iron peak element Mn. For this element, we compute the evolution in the three systems the Galactic bulge, the Solar neighbourhood Sagittarius; we find that to reproduce simultaneously the measurements of [Mn/Fe] versus [Fe/H] in the three systems the type Ia supernova Mn yield mus be metallicity-dependent. We adopt two chemical evolution models for the the evolution of C and O abundances in the bulge in the thin disk. They assume the same nucleosynthesis prescriptions but different histories of star formation. In our models we consider yields from massive stars with without the inclusion of metallicity-dependent stellar winds. The observed increase in the [C/O] with metallicity in the bulge lies between the predictions utilizing mass-loss rates of Maeder Meynet & Maeder. A model without metallicity-dependent yields completely fails to match the observations. Thus, the relative increase in carbon abundance at high metallicity appears to come from metallicity-dependent stellar winds in massive stars. In the case of the neutron capture elements the comparison between the results of our standard chemical evolution model for the Milky Way halo the neutron capture abundances shown in the halo stars, indicates how to constrain the r-process contribution by massive stars to the enrichment of these elements, keeping fixed a s-process contribution by low mass stars, based on the theoretical results of the group of prof. Gallino. We show the results we obtain using these prescriptions for barium in the Bulge of our Galaxy, compared to the very recent measurements of this neutron capture elements by Bensby et al. based on microlensing effect in bulge stars.

Gabriele, Cescutti; Francesca, Matteucci

2010-08-01

20

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

E-print Network

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.

David C. Brydges; Gordon Slade

2014-11-25

21

Determination of the CKM Element V(Ub)  

SciTech Connect

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.

Fortin, Dominique; /Victoria U.

2007-04-06

22

Group classification of variable coefficient KdV-like equations  

E-print Network

The exhaustive group classification of the class of KdV-like equations with time-dependent coefficients $u_t+uu_x+g(t)u_{xxx}+h(t)u=0$ is carried out using equivalence based approach. A simple way for the construction of exact solutions of KdV-like equations using equivalence transformations is described.

Vaneeva, Olena

2012-01-01

23

Platinum-group elements: so many excellent properties  

USGS Publications Warehouse

The platinum-group elements (PGE) include platinum, palladium, rhodium, ruthenium, iridium, and osmium. These metals have similar physical and chemical properties and occur together in nature. The properties of PGE, such as high melting points, corrosion resistance, and catalytic qualities, make them indispensable to many industrial applications. PGE are strategic and critical materials for many nations because they are essential for important industrial applications but are mined in a limited number of places and have no adequate substitutes. Exploration and mining companies have found approximately 104,000 metric tons of PGE (with minor gold) in mineral deposits around the world that could be developed. For PGE, almost all known production and resources are associated with three geologic features: the Bushveld Complex, a layered mafic-to-ultramafic intrusion in South Africa; the Great Dyke, a layered mafic-to-ultramafic intrusion in Zimbabwe; and sill-like intrusions associated with flood basalts in the Noril’sk-Talnakh area, Russia. To help predict where PGE supplies might be located, USGS scientists study how and where PGE resources are concentrated in the Earth's crust and use that knowledge to assess the likelihood that undiscovered PGE deposits may exist. Techniques used for assessing mineral resources were developed by the USGS to support the stewardship of Federal lands and evaluate mineral resource availability in a global context. The USGS also compiles statistics and information on the worldwide supply, demand, and flow of PGE. These data are all used to inform U.S. national policymakers.

Zientek, Michael L.; Loferski, Patricia J.

2014-01-01

24

Bioaccessibility of platinum group elements in automotive catalytic converter particulates.  

PubMed

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

Turner, Andrew; Price, Simon

2008-12-15

25

All-electron and relativistic pseudopotential studies for the group 1 element polarizabilities from K to element 119  

NASA Astrophysics Data System (ADS)

Two-component and scalar relativistic energy-consistent pseudopotentials for the group 1 elements from K to element 119 are presented using nine electrons for the valence space definition. The accuracy of such an approximation is discussed for dipole polarizabilities and ionization potentials obtained at the coupled-cluster level as compared to experimental and all-electron Douglas-Kroll results.

Lim, Ivan S.; Schwerdtfeger, Peter; Metz, Bernhard; Stoll, Hermann

2005-03-01

26

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

27

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

E-print Network

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 $\\log \\epsilon_\\mathrm{Sc}=3.16\\pm0.04$, $\\log \\epsilon_\\mathrm{Ti}=4.90\\pm0.04$, $\\log \\epsilon_\\mathrm{V}=3.89\\pm0.08$, $\\log \\epsilon_\\mathrm{Cr}=5.62\\pm0.04$, $\\log \\epsilon_\\mathrm{Mn}=5.42\\pm0.04$, $\\log \\epsilon_\\mathrm{Fe}=7.47\\pm0.04$, $\\log \\epsilon_\\mathrm{Co}=4.93\\pm0.05$ and $\\log \\epsilon_\\mathrm{Ni}=6.20\\pm0.04$. Our uncertainties factor in both statistical and systematic errors (the latter estimated for possible errors in the model atmospheres and NLTE line formation). The ...

Scott, Pat; Grevesse, Nicolas; Bergemann, Maria; Sauval, A Jacques

2014-01-01

28

Jones Zone of Group V Semimetals As and Sb  

Microsoft Academic Search

Band structures on the Jones zone boundary are calculated for group V semimetals arsenic and antimony by the pseudopotential method. Jones zone concept is shown to be useful for clear understanding of bonding-antibonding energy gap. Peculiarity of crystal structure is discussed on the basis of the perturbation theory of cohesive energy reinforced with the Jones zone concept. It is shown

Masao Iwamatsu

1980-01-01

29

Benchmarking of the 99-group ANSL-V library  

SciTech Connect

The purpose of this paper is to present thermal benchmark data testing results for the BAPL-1, TRX-1, and SEEP-1 lattices, using selected processed cross-sections from the ANSL-V 99-group library. 7 refs., 1 tab.

Wright, R.Q.; Ford, W.E. III; Greene, N.M.; Petrie, L.M.; Primm, R.T. III; Westfall, R.M.

1987-01-01

30

Nitrogen Adsorption, Solubility and Transport within Group V Metals  

NASA Astrophysics Data System (ADS)

It is well known that Group V metals have strong-binding characteristics to diatomic molecule, e.g. N2, O2, H2, and CO. Within this study, N2 has been investigated to determine the mechanism of surface adsorption, dissociation and subsequent atomic diffusion into the bulk crystal structure of vanadium(V). Alloys of ruthenium(Ru)-V have been examined indicating that Ru can be used to tune the electronic structure of the bulk to enhance atomic diffusion. Electronic structure calculations based on density functional theory have been studied on the investigation of N2 adsorption on 3 low-index surfaces, (110), (100) and (111). Preliminary investigations indicate that the V(111) surface binds N2 the strongest at fcc site (Eads = 1.4eV). To determine bulk solubility, binding energy calculations are carried out as a function of N concentration. N was found to be stable primarily at O-sites within the bulk V lattice. Bader charge and density of states analyses are analyzed to investigate the mechanism of bulk absorption and solubility phenomena. Results will be presented on the adsorption, bulk solubility, and transport of N in V and V-based alloys. The application to this study is toward the design of an N2-selective dense membrane in which atomic N may be produced on the permeate side with hydrogen as a sweep gas for the ammonia synthesis process.

Rochana, Panithita; Ozdogan, Ekin; Wilcox, Jennifer

2011-03-01

31

Molecular nitrides with titanium and Group 13-15 elements.  

PubMed

Several heterometallic nitrido complexes were prepared by reaction of the imido-nitrido titanium complex [{Ti(eta(5)-C(5)Me(5))(mu-NH)}(3)(mu(3)-N)] (1) with amido derivatives of Group 13-15 elements. Treatment of 1 with bis(trimethylsilyl)amido [M{N(SiMe(3))(2)}(3)] derivatives of aluminum, gallium, or indium in toluene at 150-190 degrees C affords the single-cube amidoaluminum complex [{(Me(3)Si)(2)N}Al{(mu(3)-N)(2)(mu(3)-NH)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}] (2) or the corner-shared double-cube compounds [M(mu(3)-N)(3)(mu(3)-NH)(3){Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}(2)] [M = Ga (3), In (4)]. Complexes 3 and 4 were also obtained by treatment of 1 with the trialkyl derivatives [M(CH(2)SiMe(3))(3)] (M = Ga, In) at high temperatures. The analogous reaction of 1 with [{Ga(NMe(2))(3)}(2)] at 110 degrees C leads to [{Ga(mu(3)-N)(2)(mu(3)-NH)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}(2)] (5), in which two [GaTi(3)N(4)] cube-type moieties are linked through a gallium-gallium bond. Complex 1 reacts with one equivalent of germanium, tin, or lead bis(trimethylsilyl)amido derivatives [M{N(SiMe(3))(2)}(2)] in toluene at room temperature to give cube-type complexes [M{(mu(3)-N)(2)(mu(3)-NH)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}] [M = Ge (6), Sn (7), Pb (8)]. Monitoring the reaction of 1 with [Sn{N(SiMe(3))(2)}(2)] and [Sn(C(5)H(5))(2)] by NMR spectroscopy allows the identification of intermediates [RSn{(mu(3)-N)(mu(3)-NH)(2)Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}] [R = N(SiMe(3))(2) (9), C(5)H(5) (10)] in the formation of 7. Addition of one equivalent of the metalloligand 1 to a solution of lead derivative 8 or the treatment of 1 with a half equivalent of [Pb{N(SiMe(3))(2)}(2)] afford the corner-shared double-cube compound [Pb(mu(3)-N)(2)(mu(3)-NH)(4){Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}(2)] (11). Analogous antimony and bismuth derivatives [M(mu(3)-N)(3)(mu(3)-NH)(3){Ti(3)(eta(5)-C(5)Me(5))(3)(mu(3)-N)}(2)] [M = Sb (12), Bi (13)] were obtained through the reaction of 1 with the tris(dimethylamido) reagents [M(NMe(2))(3)]. Treatment of 1 with [AlCl(2){N(SiMe(3))(2)}(OEt(2))] affords the precipitation of the singular aluminum-titanium square-pyramidal aggregate [{{(Me(3)Si)(2)N}Cl(3)Al(2)}(mu(3)-N)(mu(3)-NH)(2){Ti(3)(eta(5)-C(5)Me(5))(3)(mu-Cl)(mu(3)-N)}] (14). The X-ray crystal structures of 5, 11, 13, 14, and [AlCl{N(SiMe(3))(2)}(2)] were determined. PMID:19544507

García-Castro, María; Martín, Avelino; Mena, Miguel; Yélamos, Carlos

2009-07-20

32

Elements of Mathematics, Book 10: Groups and Rings.  

ERIC Educational Resources Information Center

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…

Exner, Robert; And Others

33

Trace element seasonality in marine macroalgae of different functional-form groups.  

PubMed

Novel information on the seasonality of element accumulation in seaweeds is provided. Seasonal patterns of As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, Sr, U, V and Zn concentrations in macroalgae belonging to different functional-form groups (Ulva intestinalis, Ulva rigida, Codium fragile, Gracilaria gracilis) from the Thessaloniki Gulf, Aegean Sea were determined and compared. Uni- and multivariate data analyses were applied. Element concentrations generally decreased during spring and/or summer, probably due to the growth effect, but a reverse trend, particularly in Ulva species, was also observed. Most elements (Cd, Co, Cr, Cu, Mo, Ni, Pb, Sr) in Ulva species displayed a comparatively low monthly variability, indicating that the extent of seasonal variation is closely related to thallus morphology and growth strategy. In particular, these data suggest that Cd, Co, Cr, Cu, Mo, Ni, Pb and Sr contents in fast-growing, sheet-like macroalgae are less influenced by the season, compared to their contents in coarsely-branched and thick-leathery macroalgae; therefore, sheet-like macroalgae may be more appropriate to be used in biomonitoring of coastal waters. The data presented could be utilized in the development of biomonitoring programmes for the protection of coastal environments. PMID:25460058

Malea, Paraskevi; Chatziapostolou, Anastasia; Kevrekidis, Theodoros

2015-02-01

34

Current Light Elements of the ? Scuti Star V393 Carinae  

NASA Astrophysics Data System (ADS)

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.

Axelsen, R. A.

2014-12-01

35

Z .Chemical Geology 157 1999 219234 z /Quantifying the platinum group elements PGEs and gold in  

E-print Network

Z .Chemical Geology 157 1999 219­234 z /Quantifying the platinum group elements PGEs and gold for analyzing low abundances of the platinum group elements PGEs and gold has been developed using Z .cation--Ru, Rh, Pd, Os, Ir and Pt and gold Au ) Corresponding author are typically present in common terrestrial

36

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

E-print Network

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

Zalesskii, Pavel

37

Spectroscopy of XY 3Z (C 3 v) radicals with an odd number of electrons: A tensorial formalism adapted to the SU(2)?CI?C?vS?C3vS group chain  

NASA Astrophysics Data System (ADS)

A tensorial formalism adapted to the case of XY 3Z symmetric tops with half integer angular momenta is proposed as an extension of the formalism for the group chain O (3) ? C? v ? C3 v developed in a recent paper [A. El Hilali, V. Boudon, M. Loëte, J. Mol. Spectrosc. 234 (2005) 113-121]. We use the chain SU(2)?CI?C?vS?C3vS, where GS ( G being C? v or C3 v) is the G point group with its spinorial representations. Coupling coefficients and formulas for the computation of matrix elements of the tensor operators are derived for this chain. A deduction of coupling coefficients (Clebsch-Gordan, 6 C, 9 C, …) and similar formulas is proposed for the group C3vS itself.

El Hilali, A.; Boudon, V.; Loëte, M.

2006-09-01

38

Method of fabricating vertically aligned group III-V nanowires  

DOEpatents

A top-down method of fabricating vertically aligned Group III-V micro- and nanowires uses a two-step etch process that adds a selective anisotropic wet etch after an initial plasma etch to remove the dry etch damage while enabling micro/nanowires with straight and smooth faceted sidewalls and controllable diameters independent of pitch. The method enables the fabrication of nanowire lasers, LEDs, and solar cells.

Wang, George T; Li, Qiming

2014-11-25

39

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

USGS Publications Warehouse

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.

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

1986-01-01

40

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

NASA Astrophysics Data System (ADS)

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).

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

2008-03-01

41

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

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

42

Integrated learning in practical machine element design course: a case study of V-pulley design  

NASA Astrophysics Data System (ADS)

To achieve an effective integrated learning in Machine Element Design course, it is of importance to bridge the basic knowledge and skills of element designs. The multiple core learning leads the pathway which consists of two main parts. The first part involves teaching documents of which the contents are number of V-groove formulae, standard of V-grooved pulleys, and parallel key dimension's formulae. The second part relates to the subjects that the students have studied prior to participating in this integrated learning course, namely Material Selection, Manufacturing Process, Applied Engineering Drawing, CAD (Computer Aided Design) animation software. Moreover, an intensive cooperation between a lecturer and students is another key factor to fulfill the success of integrated learning. Last but not least, the students need to share their knowledge within the group and among the other groups aiming to gain knowledge of and skills in 1) the application of CAD-software to build up manufacture part drawings, 2) assembly drawing, 3) simulation to verify the strength of loaded pulley by method of Finite Element Analysis (FEA), 4) the software to create animation of mounting and dismounting of a pulley to a shaft, and 5) an instruction manual. The end product of this integrated learning, as a result of the above 1 to 5 knowledge and skills obtained, the participating students can create an assembly derived from manufacture part drawings and a video presentation with bilingual (English-Thai) audio description of Vpulley with datum diameter of 250 mm, 4 grooves, and type of groove: SPA.

Tantrabandit, Manop

2014-06-01

43

Lifetimes of Rydberg states for ions of the group 2 elements  

NASA Astrophysics Data System (ADS)

An analysis is given of data in the literature on radiative lifetimes of excited ionic states for elements of group 2 of the Periodic Table. Tabular values of constants are recommended on the basis of the analysis.

Rykova, O. V.; Verolainen, Ya. F.

1994-01-01

44

ON THE NUMBER OF CONJUGACY CLASSES OF -ELEMENTS IN FINITE GROUPS  

E-print Network

ON THE NUMBER OF CONJUGACY CLASSES OF -ELEMENTS IN FINITE GROUPS ATTILA MAROTI AND HUNG NGOC NGUYEN;2 ATTILA MAROTI AND HUNG NGOC NGUYEN One of the goals of this work is to impose an explicit lower bound

Maróti, Attila

45

Defect interactions of group-I elements in cubic II-VI compounds  

NASA Astrophysics Data System (ADS)

By means of perturbed ?? angular correlation (PAC) experiments using the radioactive dopants 77Br, 111Ag, and 111In, the behavior of the group-I elements Li, Cu, Ag, and Au is investigated. Group-I elements are shown to form nearest- (NN) and next-nearest-neighbor donor-acceptor pairs in the II-VI semiconductor CdTe. The simultaneous occurrence of cation vacancies indicates the transition of group-I elements from substitutional to interstitial lattice sites. In case of NN pairs, the electric-field gradients measured in the PAC experiments are compared with those obtained theoretically by density-functional theory calculations. PAC experiments performed in ZnTe and ZnSe show a similar behavior regarding the donor-acceptor pairing with group-I elements in these compounds.

Ostheimer, V.; Lany, S.; Hamann, J.; Wolf, H.; Wichert, Th.; ISOLDE Collaboration

2003-12-01

46

Platinum-group element micronuggets and refertilization process in Lherz orogenic peridotite (northeastern Pyrenees, France)  

E-print Network

Platinum-group element micronuggets and refertilization process in Lherz orogenic peridotite: R.W. Carlson Keywords: highly siderophile elements upper mantle orogenic peridotites platinum by Pyrenean orogenic peridotite massifs are unexpectedly rich in 0.5­3 µm large micronuggets of platinum

Demouchy, Sylvie

47

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

Microsoft Academic Search

.   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

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

1998-01-01

48

Platinum group elements in the environment: emissions and exposure.  

PubMed

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

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

2009-01-01

49

A Group-Theoretical Approach to the Periodic Table of Chemical Elements: Old and New Developments  

E-print Network

This paper is a companion article to the review paper by the present author devoted to the classification of matter constituents (chemical elements and particles) and published in the first part of the proceedings of The Second Harry Wiener International Memorial Conference (see quant-ph/0310155). It is mainly concerned with a group-theoretical approach to the Periodic Table of the neutral elements based on the noncompact group SO(4,2)xSU(2).

M. R. Kibler

2005-03-03

50

Determinations of quark mixing matrix elements $|V_{cd}|$ and $|V_{cs}|$ from leptonic and semileptonic $D$ Decays  

E-print Network

With the recent measurements of purely leptonic $D^+_{(s)}$ decays and semileptonic $D$ decays in conjunction with decay constants $f_{D^+_{(s)}}$ and form factors $f^{\\pi(K)}_+(0)$ calculated in LQCD, we extract the magnitudes of $V_{cd}$ and $V_{cs}$ to be $|V_{cd}|=0.218\\pm0.005$ and $|V_{cs}|=0.987\\pm0.016$. Compared to those given in PDG2013, the precisions of these newly extracted $|V_{cd}|$ and $|V_{cs}|$ are improved by more than 2.0 and 1.5 factors, respectively. With the newly extracted $|V_{cd}|$ and $|V_{cs}|$ together with other CKM matrix elements given in PDG2013, we check the unitarity of the CKM matrix, which are $|V_{ud}|^2+|V_{cd}|^2+|V_{td}|^2=0.997\\pm0.002$, $|V_{us}|^2+|V_{cs}|^2+|V_{ts}|^2=1.027\\pm0.032$ and $|V_{cd}|^2+|V_{cs}|^2+|V_{cb}|^2=1.023\\pm0.032$.

G. Rong; Y. Fang; H. L. Ma

2014-09-03

51

et al. demonstrate that the 18-kb element in V. cholerae also circularizes after phage infec-  

E-print Network

et al. demonstrate that the 18-kb element in V. cholerae also circularizes after phage infec- tion-targeting spacers, showed that it could replicate and kill a PLE-harbouringV. cholerae strain that had been isolated V. cholerae strain lacking the PLE, further supporting the targeted action of the system

Ghazanfar, Asif

52

Concentrations of platinum group elements in 122 U.S. coal samples  

USGS Publications Warehouse

Analysis of more than 13,000 coal samples by semi-quantitative optical emission spectroscopy (OES) indicates that concentrations of the platinum group elements (iridium, palladium, platinum, osmium, rhodium, and ruthenium) are less than 1 ppm in the ash, the limit of detection for this method of analysis. In order to accurately determine the concentration of the platinum group elements (PGE) in coal, additional data were obtained by inductively coupled plasma mass spectroscopy, an analytical method having part-per-billion (ppb) detection limits for these elements. These data indicate that the PGE in coal occur in concentrations on the order of 1 ppb or less.

Oman, C.L.; Finkelman, R.B.; Tewalt, S.J.

1997-01-01

53

On a group-theoretical approach to the periodic table of chemical elements  

E-print Network

This paper is concerned with the application of the group SO(4,2)xSU(2) to the periodic table of chemical elements. It is shown how the Madelung rule of the atomic shell model can be used for setting up a periodic table that can be further rationalized via the group SO(4,2)xSU(2) and some of its subgroups. Qualitative results are obtained from the table and the general lines of a programme for a quantitative approach to the properties of chemical elements are developed on the basis of the group SO(4,2)xSU(2).

Maurice Robert Kibler

2004-08-16

54

The bcr1 DNA Repeat Element Is Specific to the Bacillus cereus Group and Exhibits Mobile Element Characteristics  

PubMed Central

Bacillus cereus strains ATCC 10987 and ATCC 14579 harbor a ?155-bp repeated element, bcr1, which is conserved in B. cereus, B. anthracis, B. thuringiensis, and B. mycoides but not in B. subtilis and B. licheniformis. In this study, we show by Southern blot hybridizations that bcr1 is present in all 54 B. cereus group strains tested but absent in 11 Bacillus strains outside the group, suggesting that bcr1 may be specific and ubiquitous to the B. cereus group. By comparative analysis of the complete genome sequences of B. cereus ATCC 10987, B. cereus ATCC 14579, and B. anthracis Ames, we show that bcr1 is exclusively present in the chromosome but absent from large plasmids carried by these strains and that the numbers of full-length bcr1 repeats for these strains are 79, 54, and 12, respectively. Numerous copies of partial bcr1 elements are also present in the three genomes (91, 128, and 53, respectively). Furthermore, the genomic localization of bcr1 is not conserved between strains with respect to chromosomal position or organization of gene neighbors, as only six full-length bcr1 loci are common to at least two of the three strains. However, the intergenic sequence surrounding a specific bcr1 repeat in one of the three strains is generally strongly conserved in the other two, even in loci where bcr1 is found exclusively in one strain. This finding indicates that bcr1 either has evolved by differential deletion from a very high number of repeats in a common ancestor to the B. cereus group or is moving around the chromosome. The identification of bcr1 repeats interrupting genes in B. cereus ATCC 10987 and ATCC 14579 and the presence of a flanking TTTAT motif in each end show that bcr1 exhibits features characteristic of a mobile element. PMID:15516586

Økstad, Ole Andreas; Tourasse, Nicolas J.; Stabell, Fredrik B.; Sundfær, Cathrine K.; Egge-Jacobsen, Wolfgang; Risøen, Per Arne; Read, Timothy D.; Kolstø, Anne-Brit

2004-01-01

55

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

SciTech Connect

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.

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

2014-05-01

56

The structure of countable primary abelian groups and primary abelian groups without elements of infinite height  

E-print Network

?&) & . (&?54' (&?|i) ) "(&?7);, -. - V?&)t (&?))i -(P?R)i (P?$));4&?4)j:(3?9')'&:'($?6')t, 0'?V)' (0?0)'q. (Oj'R)I-gr?0)g (0?6) 6 eP5:W (B?04 . (~?&)i" (&?@). ( . (R?6) Ofs ~, HC t? RQ e I(0?O)y 84h. )) 8~'-:W'. R. 4 a &ef, e 8 5f'Ie I(@?0)) X& -:j e...~ ~&~XX'g. y q'~ y 'y q p" e y e e j'e 4, e e's w'. 'e s' "'li9 APP~kX. XX Q 8 @ 0 e L b C fD I 8. 8, CI 4 I el e a I 0', , 0Q Sy ' 'HXBRXC@~'f y. 'e y' 'a a, e o e e e y e a s e t o OI. O' 8 '?. ?, ';'o". . 'eo O ' 'j COCpXCI48-:&X'~4. 415+ CFQaP e o...

Heatherly, Henry Edward

1962-01-01

57

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

E-print Network

An experimental study of mass transfer of platinum-group elements, gold, nickel and copper of an experimental study on platinum-group elements (PGE) and Au mass transfer by an S-vapor in the Fe­Ni­Cu sulfide complexes. In contrast, Cu and Au show no correlation with f S2 suggesting that these elements

Long, Bernard

58

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

SciTech Connect

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.

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

2010-01-01

59

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

USGS Publications Warehouse

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.

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

2000-01-01

60

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

Microsoft Academic Search

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

Maria Balcerzak

2011-01-01

61

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

Microsoft Academic Search

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

Ofelia Morton; Harald Puchelt; Elizabeth Hernández; Elena Lounejeva

2001-01-01

62

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

Microsoft Academic Search

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

László Bencs; Khaiwal Ravindra; René Van Grieken

2003-01-01

63

Development of an analytical method for monitoring worker populations exposed to platinum-group elements  

Microsoft Academic Search

The increasing industrial use of platinum-group elements (PGEs), namely Ir, Pd, Pt and Rh, and related allergies such as rhinitis, conjunctivitis, asthma, urticaria and contact dermatitis, have led to a growing need to monitor selected populations of exposed workers. In this study, the levels of PGEs were measured in indoor airborne particulate matter and in biological samples taken from employees

Francesco Petrucci; Nicola Violante; Oreste Senofonte; Marco De Gregorio; Alessandro Alimonti; Sergio Caroli; Giovanni Forte; Antonio Cristaudo

2004-01-01

64

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

Microsoft Academic Search

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

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

2007-01-01

65

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

Microsoft Academic Search

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

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

2004-01-01

66

A Group-Theoretical Approach to the Periodic Table of Chemical Elements: Old and New Developments  

E-print Network

A Group-Theoretical Approach to the Periodic Table of Chemical Elements: Old and New Developments as an invited talk to The Second Harry Wiener International Memorial Conference: "The Periodic Table in The Mathematics of the Periodic Table, D.H. Rouvray and R.B. King, Eds., Nova Science Publishers, New York, 2005

Paris-Sud XI, Université de

67

IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION  

EPA Science Inventory

The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

68

Research paper The concentration of platinum-group elements and gold in southern African and  

E-print Network

and Karelian kimberlite-hosted mantle xenoliths: Implications for the noble metal content of the Earth's mantle of the platinum-group elements and gold in 111 mantle xenoliths from more than 20 kimberlite pipes in southern craton on Earth, in part owing to an abundance of mantle xenoliths derived from kimberlites. Study

69

The growth and properties of mixed group V nitrides  

NASA Astrophysics Data System (ADS)

Bearing in mind the problems of finding a lattice-matched substrate for the growth of binary group III nitride films and the detrimental effect of the large activation energy associated with acceptors in GaN, we propose the study of the alloy system AlGaAsN. We predict that it may be possible to obtain a direct gap alloy, with a band gap as wide as 2.8eV, which is lattice-matched to silicon substrates. The paper reports our attempts to grow GaAsN alloy films by molecular beam epitaxy on either GaAs or GaP substrates, using a radio frequency plasma source to supply active nitrogen. Auger electron spectra demonstrate that it is possible to incorporate several tens of percent of nitrogen into GaAs films, though x-ray diffraction measurements show that such films contain mixed binary phases rather than true alloys. An interesting observation concerns the fact that it is possible to control the crystal structure of GaN films by the application of an As flux during growth. In films grown at 620°C a high As flux tends to increase the proportion of cubic GaN while also resulting in the incorporation of GaAs. Films grown at 700°C show no evidence for GaAs incorporation; at this temperature, it is possible to grow either purely cubic or purely hexagonal GaN depending on the presence or absence of the As beam.

Orton, J. W.; Lacklison, D. E.; Baba-Ali, N.; Foxon, C. T.; Cheng, T. S.; Novikov, S. V.; Johnston, D. F. C.; Hooper, S. E.; Jenkins, L. C.; Challis, L. J.; Tansley, T. L.

1995-04-01

70

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

Code of Federal Regulations, 2014 CFR

...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...

2014-07-01

71

The Element Effect Revisited: Factors Determining Leaving Group Ability in Activated Nucleophilic Aromatic Substitution Reactions  

PubMed Central

The “element effect” in nucleophilic aromatic substitution reactions (SNAr) is characterized by the leaving group order, F > NO2 > Cl ? Br > I, in activated aryl halides. Multiple causes for this result have been proposed. Experimental evidence shows that the element effect order in the reaction of piperidine with 2,4-dinitrophenyl halides in methanol is governed by the differences in enthalpies of activation. Computational studies of the reaction of piperidine and dimethylamine with the same aryl halides using the polarizable continuum model (PCM) for solvation indicate that polar, polarizability, solvation, and negative hyperconjugative effects are all of some importance in producing the element effect in methanol. In addition, a reversal of polarity of the C–X bond from reactant to transition state in the case of ArCl and ArBr compared to ArF also contributes to their difference in reactivity. The polarity reversal, and hyperconjugative influences have received little or no attention in the past. Nor has differential solvation of the different transition states been strongly emphasized. An anionic nucleophile, thiolate, gives very early transition states and negative activation enthalpies with activated aryl halides. The element effect is not established for these reactions. We suggest that the leaving group order in the gas phase will be dependent on the exact combination of nucleophile, leaving group, and substrate framework. The geometry of the SNAr transition state permits useful, qualitative conceptual distinctions to be made between this reaction and other modes of nucleophilic attack. PMID:23057717

Senger, Nicholas A.; Bo, Bo; Cheng, Qian; Keeffe, James R.; Gronert, Scott; Wu, Weiming

2012-01-01

72

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 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...

2011-04-01

73

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

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 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...

2010-04-01

74

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

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 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...

2012-04-01

75

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

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 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...

2013-04-01

76

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

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 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...

2014-04-01

77

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

NASA Astrophysics Data System (ADS)

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.

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

2012-01-01

78

Platinum Group Element Preconcentration by NiS Fire-Assay;Suitable for Microbeam Techniques?  

Microsoft Academic Search

NiS fire assay preconcentration can be used to analyse whole rock for Platinum-Group Elements (PGE) and to prepare matrix matched reference material (RM). For microbeam techniques, the sample must be solid and NiS preconcentration is a technique worth evaluating. Because some techniques such as laser-ablation inductively-coupled-plasma quadrupole-mass-spectrometry (LA-ICP-QMS) do not have sufficently low quantification limits for PGE, preconcentration is necessary.

L. P. Bedard

2004-01-01

79

Minority carrier device comprising a passivating layer including a Group 13 element and a chalcogenide component  

NASA Technical Reports Server (NTRS)

A minority carrier device includes at least one junction of at least two dissimilar materials, at least one of which is a semiconductor, and a passivating layer on at least one surface of the device. The passivating layer includes a Group 13 element and a chalcogenide component. Embodiments of the minority carrier device include, for example, laser diodes, light emitting diodes, heterojunction bipolar transistors, and solar cells.

Barron, Andrew R. (Inventor); Hepp, Aloysius F. (Inventor); Jenkins, Phillip P. (Inventor); MacInnes, Andrew N. (Inventor)

1999-01-01

80

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

E-print Network

Slope stability analysis by ®nite elements D. V. GRIFFITHS� and P. A. LANE{ The majority of slope stability analysis which is accu- rate, versatile and requires fewer a priori assumptions, especially the zones in which the shear strength of the soil is insuf®- cient to resist the shear stresses. The paper

81

Fully relativistic study of intermetallic dimers of group-1 elements K through element 119 and prediction of their adsorption on noble metal surfaces  

Microsoft Academic Search

Spectroscopic properties of group-1 M2 and MAu (M=K, Rb, Cs, Fr, and element 119) were calculated using the 4c-DFT method. The results show that the relativistic contraction and stabilization of the ns(M) AO result in the inversion of trends both in atomic and molecular properties in group 1 beyond Cs. Electronegativity ? of the elements proves to decrease from Cs,

V. Pershina; A. Borschevsky; J. Anton

82

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

NASA Astrophysics Data System (ADS)

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).

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

2014-05-01

83

Composition, apparatus, and process, for sorption of gaseous compounds of group II-VII elements  

DOEpatents

Scavenger compositions are disclosed, which have utility for effecting the sorptive removal of hazardous gases containing Group II-VII elements of the Periodic Table, such as are widely encountered in the manufacture of semiconducting materials and semiconductor devices. Gas sorption processes including the contacting of Group II-VII gaseous compounds with such scavenger compositions are likewise disclosed, together with critical space velocity contacting conditions pertaining thereto. Further described are gas contacting apparatus, including mesh structures which may be deployed in gas contacting vessels containing such scavenger compositions, to prevent solids from being introduced to or discharged from the contacting vessel in the gas stream undergoing treatment. A reticulate heat transfer structure also is disclosed, for dampening localized exothermic reaction fronts when gas mixtures comprising Group II-VII constituents are contacted with the scavenger compositions in bulk sorption contacting vessels according to the invention.

Tom, Glenn M. (New Milford, CT); McManus, James V. (Danbury, CT); Luxon, Bruce A. (Stamford, CT)

1991-08-06

84

Universality in Similarity Renormalization Group Evolved Potential Matrix Elements and T-Matrix Equivalence  

E-print Network

We examine how the universality of two-nucleon interactions evolved using similarity renormalization group (SRG) transformations correlates with T-matrix equivalence, with the ultimate goal of gaining insight into universality for three-nucleon forces. With sufficient running of the SRG flow equations, the low-energy matrix elements of different realistic potentials evolve to a universal form. Because these potentials are fit to low-energy data, they are (approximately) phase equivalent only up to a certain energy, and we find universality in evolved potentials up to the corresponding momentum. More generally we find universality in local energy regions, reflecting a local decoupling by the SRG. The further requirements for universality in evolved potential matrix elements are explored using two simple alternative potentials. We see evidence that in addition to predicting the same observables, common long-range potentials (i.e., explicit pion physics) is required for universality in the potential matrix elements after SRG flow. In agreement with observations made previously for Vlowk evolution, regions of universal potential matrix elements are restricted to where half-on-shell T-matrix equivalence holds.

B. Dainton; R. J. Furnstahl; R. J. Perry

2014-01-27

85

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

86

The multivariate Charlier polynomials as matrix elements of the Euclidean group representation on oscillator states  

E-print Network

A family of multivariate orthogonal polynomials generalizing the standard (univariate) Charlier polynomials is shown to arise in the matrix elements of the unitary representation of the Euclidean group E(d) on oscillator states. These polynomials in d discrete variables are orthogonal on the product of d Poisson distributions. The accent is put on the d=2 case and the group theoretical setting is used to obtain the main properties of the polynomials: orthogonality and recurrence relations, difference equation, raising/lowering relations, generating function, hypergeometric and integral representations and explicit expression in terms of standard Charlier and Krawtchouk polynomials. The approach is seen to extend straightforwardly to an arbitrary number of variables. The contraction of SO(3) to E(2) is used to show that the bivariate Charlier polynomials correspond to a limit of the bivariate Krawtchouk polynomials.

Vincent X. Genest; Hiroshi Miki; Luc Vinet; Alexei Zhedanov

2014-04-04

87

Verification of brittle fracture criteria for elements with V-shaped notches  

Microsoft Academic Search

In this paper an analysis of crack initiation in plane elements with V-shaped notches under biaxial loading (mode I and II) was presented. The following fracture criteria were used to evaluate the critical loads and directions of crack initiation: strain energy release rate criterion; strain energy density criterion; modified McClintock's stress criterion; non-local stress criterion.Results of numerical analysis obtained using

Andrzej Seweryn; Andrzej ?ukaszewicz

2002-01-01

88

New SSMS Techniques for the Determination of Rhodium and Other Platinum- Group Elements in Carbonaceous Chondrites  

NASA Astrophysics Data System (ADS)

We have developed new spark source mass spectrometric (SSMS) techniques for simultaneous analysis of platinum-group elements (PGE) together with other trace elements in stony meteorites. We have measured elemental abundances of Rh, Ru, Os, Ir, Pt, Au in carbonaceous chondrites of different types including the two CI chondrites Orgueil and Ivuna. These data are relevant for the determination of solar-system abundances. Whereas the solar-system abundances of most PGE are well known, this is not the case for Rh, and no literature data exist for carbonaceous chondrites, mainly because of analytical difficulties. The SSMS techniques include new calibration procedures and the use of a recently developed multi-ion counting (MIC) system [1]. The mono-isotopic element Rh and the other PGE were determined by using internal standard elements (e.g., Nd, U) that were measured by isotope dilution in the same sample electrode material. The data were calibrated with certified standard solutions of PGE which were doped on trace-element poor rock samples. Ion abundances were measured using both the conventional photoplate detection and the ion-counting techniques. The new MIC technique that uses up to 20 small channeltrons for ion counting measurements has the advantage of improved precision, detection limits and analysis time compared to photoplate detection. Tab. 1 shows the Rh analyses for the meteorites Orgueil, Ivuna, Murchison, Allende and Karoonda obtained by conventional photoplate detection. These are the first Rh results for carbonaceous chondrites. The data for the two CI chondrites Orgueil and Ivuna are identical and agree within 4 % with the CI estimate of Anders and Grevesse [2] which was derived indirectly from analyses for H-chondrites. The PGE Os, Ir, Pt, Au and W, Re, Th, U concentrations were determined by both detection systems. Data obtained with the MIC system are more precise (about 4% for concentrations in the ppb range) compared to the photoplate detection system (about 10 - 15 %). Both data sets agree within error limits. Rhodium correlates well with Pt and other PGE indicating no significant fractionation between the different types of carbonaceous chondrites (Tab. 1). References: [1] Jochum K. P. et al. (1994) Fresenius J. Anal. Chem., 350, 642-644. [2] Anders E. and Grevesse N. (1989) GCA, 53, 197-214.

Jochum, K. P.; Seufert, H. M.

1995-09-01

89

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

NASA Astrophysics Data System (ADS)

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.

Werner, Klaus

2014-10-01

90

Groups III and V impurity solubilities in silicon due to laser, flash, and solid-phase-epitaxial-regrowth anneals  

SciTech Connect

In this work the authors studied impurity solubilities of groups III and V elements in silicon resulting from laser anneal, flash anneal, and solid-phase-epitaxial regrowth. Rutherford backscattering channeling analysis was used to determine substitutional impurity depth profiles generated from the difference between the random and aligned spectra. Despite the large difference in peak temperatures and times, the anneals produce similar results with maximum solubilities beating the maximum equilibrium values by one to two orders of magnitude depending on the impurity. The correlation between the metastable solubility and the equilibrium distribution coefficient allows a prediction of values for other impurities not extracted experimentally.

Duffy, R.; Dao, T.; Tamminga, Y.; Tak, K. van der; Roozeboom, F.; Augendre, E. [Philips Research Leuven, Kapeldreef 75, 3001 Leuven (Belgium); Philips Research Laboratories Eindhoven, Prof. Holstlaan 4, 5656 AA Eindhoven (Netherlands); IMEC, Kapeldreef 75, 3001 Leuven (Belgium)

2006-08-14

91

Recent searches for superheavy elements in deep-inelastic reactions. [Approximately 7 MeV/. mu.  

SciTech Connect

New attempts have been made to synthesize superheavy elements (SHE) by nuclear reactions that may possibly form the products at low excitation energies. Survival of the superheavy elements would then be enhanced because of reduced losses from prompt fission. Classical and diffusion-model calculations of deep-inelastic reactions indicate there should be detectable yields of SHE formed with less than 30 MeV of excitation energy. Accordingly, superheavy elements have been sought in such reactions where targets of /sup 248/Cm and /sup 238/U have been irradiated with /sup 136/Xe and /sup 238/U ions. In the most recent experiments, targets of /sup 248/Cm metal (3.5 to 7 mg-cm/sup -2/) were bombarded with 1.8-GeV /sup 238/U ions from the UNILAC accelerator. The longer-lived SHE and actinides near the target Z were chemically separated, and the yields of a number of isotopes of Bk, Cf, Es, and Fm were measured. An upper limit of 30 nb was obtained for the formation of 1-h /sup 259/No. In addition to the off-line chemical recovery and search for SHE, an on-line experiment was performed to detect volatile SHE with half-lives of a minute or more. All experiments to produce and detect superheavy elements were much less than optimum because of premature failures in the Cm-metal targets. The outcome and status of these experiments and the implications of the actinide yields in estimating the chances for forming superheavy elements in the /sup 248/Cm + /sup 238/U reactions are discussed. 5 figures, 1 table.

Hulet, E.K.; Lougheed, R.W.; Nitschke, J.M.

1980-10-01

92

Improved Repetitive-Element PCR Fingerprinting for Resolving Pathogenic and Nonpathogenic Phylogenetic Groups within Escherichia coli  

PubMed Central

Repetitive-element PCR (rep-PCR) fingerprinting is a promising molecular typing tool for Escherichia coli, including for discriminating between pathogenic and nonpathogenic clones, but is plagued by irreproducibility. Using the ERIC2 and BOXA1R primers and 15 E. coli strains from the ECOR reference collection (three from each phylogenetic group, as defined by multilocus enzyme electrophoresis [MLEE], including virulence-associated group B2), we rigorously assessed the effect of extremely elevated annealing temperatures on rep-PCR's reproducibility, discriminating power, and ability to reveal MLEE-defined phylogenetic relationships. Modified cycling conditions significantly improved assay reproducibility and discriminating power, allowing fingerprints from different cyclers to be analyzed together with minimal loss of resolution. The correspondence of rep-PCR with MLEE with respect to tree structure and regression analysis of distances was substantially better with modified than with standard cycling conditions. Nonetheless, rep-PCR was only a fair surrogate for MLEE, and when fingerprints from different days were compared, it failed to distinguish between different clones within all-important phylogenetic group B2. These findings indicate that although the performance and phylogenetic fidelity of rep-PCR fingerprinting can be improved substantially with modified assay conditions, even when so improved rep-PCR cannot fully substitute for MLEE as a phylogenetic typing method for pathogenic E. coli. PMID:10702503

Johnson, James R.; O'Bryan, Timothy T.

2000-01-01

93

Characterization of the Sukinda and Nausahi ultramafic complexes, Orissa, India by platinum-group element geochemistry  

USGS Publications Warehouse

Samples of 20 chromitite, 14 ultramafic and mafic rock, and 9 laterite and soil samples from the Precambrian Sukinda and Nausahi ultramafic complexes, Orissa, India were analyzed for platinum-group elements (PGE). The maximum concentrations are: palladium, 13 parts per billion (ppb); platinum, 120 ppb; rhodium, 21 ppb; iridium, 210 ppb; and ruthenium, 630 ppb. Comparison of chondrite-normalized ratios of PGE for the chromitite samples of lower Proterozoic to Archean age with similar data from Paleozoic and Mesozoic ophiolite complexes strongly implies that these complexes represent Precambrian analogs of ophiolite complexes. This finding is consistent with the geology and petrology of the Indian complexes and suggests that plate-tectonic and ocean basin developement models probably apply to some parts of Precambrian shield areas. ?? 1985.

Page, N.J.; Banerji, P.K.; Haffty, J.

1985-01-01

94

Platinum-group element geochemistry of zoned ultramafic intrusive suites, Klamath Mountains, California and Oregon.  

USGS Publications Warehouse

Analyses for platinum-group elements of the varied rock suites of three Alaskan-type ultramafic to mafic multi-intrusive bodies are reported. Ir and Ru are less than analytical sensitivities of 100 and 20 ppb; Rh is less than or near 1 ppb. Average Pd assays vary among the rocks within intrusive complexes and between the three complexes (6.3, 13.7, 36.4 ppb); average Pt assays vary little among the same samples (27.9, 60.9, 34.0 ppb). Statistically adjusted Pt/(Pt + Pd) ratios increase in each suite from gabbro through clinopyroxenite to olivine-rich rocks, possibly owing to Pd fractionation.-G.J.N.

Gray, F.; Page, N.J.; Carlson, C.A.; Wilson, S.A.; Carlson, R.R.

1986-01-01

95

Improved and Expanded Near-IR Oscillator Strengths for Fe-group Elements  

NASA Astrophysics Data System (ADS)

The use of modern experimental techniques, including LIF lifetime and FTS branching fraction measurements, has significantly increased the scope and reliability of laboratory atomic transition probabilities in the UV and visible. However, the combination of these techniques is problematic in the IR, a region of increasing importance due to improved detector, spectrometer, and telescope technologies. The result is a significant gap between the capabilities to record new IR astronomical spectra and the data needed to sufficiently understand and analyze them. To aid in closing this gap, we are developing new laboratory techniques to measure improved and expanded sets of oscillator strengths in the near-IR (? ? 1-5 ?m), with a primary focus on the Fe-group elements. A description of the methods proposed and their applicability will be presented. Input from the astronomical community is essential in order to focus the research on those lines and atomic species representing the greatest near-IR atomic data needs.

Wood, Michael P.; Nave, Gillian

2015-01-01

96

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

97

Performance of multilayer dispersion elements from 80 to 500 eV  

SciTech Connect

We have measured the reflectivity of several multilayer dispersion elements between 80 and 500 eV. Two samples of ReW-C and one of Ni-C with 2d spacing of approximately 70 A and 150 A were tested at angles of incidence between 10/sup 0/ to 80/sup 0/. Measurements were made by fixing the incident and reflected angles (Bragg) and scanning the photon energy. Theoretical analyses of these multilayers have also been made and the results are compared with the experimental measurements.

Bartlett, R.J.; Kania, D.R.; Trela, W.J.; Kaellne, E.; Lee, P.; Spiller, E.

1983-01-01

98

Nitrogen incorporation in group III nitride arsenide materials grown by elemental source molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

Group III-nitride-arsenides are promising materials for long wavelength opto-electronic devices grown on GaAs substrates. The growth of nitride-arsenides was performed in an elemental solid source molecular beam epitaxy system with a plasma cell to supply reactive nitrogen. Growth is carried out with plasma conditions that maximize the amount of atomic nitrogen versus molecular nitrogen, as determined from the emission spectrum of the plasma. The group III growth rate controls the nitrogen concentration in the film. The photoluminescence intensity of GaNAs and GaInNAs quantum wells (QWs) increases drastically and shifts to shorter wavelengths following high temperature anneal. Nitrogen diffusion out of the QWs is responsible for the wavelength shift. We observe a decrease of interstitial nitrogen after anneal. Vertical-cavity surface-emitting lasers with GaInNAs QWs demonstrated a continuous-wave operation. To limit nitrogen diffusion, the GaAs barriers surrounding the GaInNAs QWs were replaced by GaNAs barriers. This new active region resulted in devices emitting at 1.3 ?m.

Spruytte, S. G.; Larson, M. C.; Wampler, W.; Coldren, C. W.; Petersen, H. E.; Harris, J. S.

2001-07-01

99

33 CFR 155.1052 - Response plan development and evaluation criteria for vessels carrying group V petroleum oil as a...  

Code of Federal Regulations, 2012 CFR

...criteria for vessels carrying group V petroleum oil as a primary cargo. 155.1052...criteria for vessels carrying group V petroleum oil as a primary cargo. (a) Owners...operators of vessels that carry group V petroleum oil as a primary cargo must provide...

2012-07-01

100

33 CFR 155.1052 - Response plan development and evaluation criteria for vessels carrying group V petroleum oil as a...  

Code of Federal Regulations, 2010 CFR

...criteria for vessels carrying group V petroleum oil as a primary cargo. 155.1052...criteria for vessels carrying group V petroleum oil as a primary cargo. (a) Owners...operators of vessels that carry group V petroleum oil as a primary cargo must provide...

2010-07-01

101

33 CFR 155.1052 - Response plan development and evaluation criteria for vessels carrying group V petroleum oil as a...  

Code of Federal Regulations, 2013 CFR

...criteria for vessels carrying group V petroleum oil as a primary cargo. 155.1052...criteria for vessels carrying group V petroleum oil as a primary cargo. (a) Owners...operators of vessels that carry group V petroleum oil as a primary cargo must provide...

2013-07-01

102

33 CFR 155.1052 - Response plan development and evaluation criteria for vessels carrying group V petroleum oil as a...  

Code of Federal Regulations, 2014 CFR

...criteria for vessels carrying group V petroleum oil as a primary cargo. 155.1052...criteria for vessels carrying group V petroleum oil as a primary cargo. (a) Owners...operators of vessels that carry group V petroleum oil as a primary cargo must provide...

2014-07-01

103

33 CFR 155.1052 - Response plan development and evaluation criteria for vessels carrying group V petroleum oil as a...  

Code of Federal Regulations, 2011 CFR

...criteria for vessels carrying group V petroleum oil as a primary cargo. 155.1052...criteria for vessels carrying group V petroleum oil as a primary cargo. (a) Owners...operators of vessels that carry group V petroleum oil as a primary cargo must provide...

2011-07-01

104

Platinum-group elements and melt percolation processes in Sidamo spinel peridotite xenoliths, Ethiopia, East African Rift  

Microsoft Academic Search

Platinum-group elements (Os, Ir, Ru, Rh, Pt, Pd) and gold contents have been determined along with S and modal sulfide abundances in 15 well-characterized spinel peridotite xenoliths from the Sidamo area (Gregory Rift, Ethiopia). In this xenolith suite, a group of deformed peridotites (refractory lherzolites to harzburgites) has been metasomatized by volatile-rich small melt-fractions while a group of granular peridotites

Jean-Pierre Lorand; Laurie Reisberg; Rosa Maria Bedini

2003-01-01

105

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

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

106

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

107

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

SciTech Connect

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.

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

1997-12-31

108

Therapeutic elements in a self-management approach: experiences from group participation among people suffering from chronic pain  

PubMed Central

Objective Chronic pain is a complex, multifaceted subjective experience that involves the whole person. Self-management is the dynamic and continuous process of adapting one’s situation to the cognitive, behavioral, and emotional responses necessary to maintain a satisfactory quality of life. Approaches based on cognitive behavioral therapy (CBT) are described as appropriate in assisting people suffering from chronic pain because they challenge maladaptive beliefs and behaviors in relation to pain. This study aimed to explore patients’ experiences of therapeutic elements from group participation in a chronic pain management program. Methods A qualitative research design with a phenomenological hermeneutic approach was used. Six months after participation in the 8-week course, 34 participants formulated and submitted written reports based on open-ended questions related to their group participation and self-help achievement. These reports were analyzed by elements of qualitative content analysis. Results The analysis resulted in two subthemes: “The significance of active involvement in gaining new insight” and “The significance of community and group support.” These were abstracted in the main theme: “Successful self-management is related to several significant contributions in the group.” Conclusion An active role with writing, self-revelation, and exchanges of thoughts and feelings in the group seemed to be the key tools for success. In addition, group support and access to other group members’ experiences were significant therapeutic elements. We suggest that successful self-management requires knowledge of essential therapeutic elements. In a CBT-based group approach, such elements may offer an important health care contribution. PMID:25170253

Furnes, Bodil; Natvig, Gerd Karin; Dysvik, Elin

2014-01-01

109

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

PubMed

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

Madzhidov, Timur I; Chmutova, Galina A

2013-05-16

110

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

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

111

Potential mobilization of platinum-group elements by siderophores in surface environments.  

PubMed

The emission of platinum-group elements (PGEs) from catalytic converters has led to increased environmental abundances of Pt, Pd, and Rh; however, little is known about the environmental effects and fate of these metals. Organic ligands found in soils have the potential to increase the mobility of PGEs and potentially increase the bioavailability of the metals. Here, we assessed the abilities of microbially produced iron-chelating ligands (siderophores) to complex with the PGEs. Batch experiments using the synthetic siderophore desferrioxamine-B (DFO-B) and powdered metal or oxide forms of Pt, Pd, or Rh showed that DFO-B enhances the solubility of Pt and Pd due to the formation of Pt- and Pd-DFO-B aqueous complexes, with estimated minimum stability constants on the order of 10(17-18) and 10(20-24), respectively. Dissolution rates for Pd are comparable to other mineral dissolution rates with DFO-B. DFO-B had little to no effect on the dissolution of Rh metal or Rh2O3. Our results indicate that siderophores have the potential to increase the mobility of Pt and Pd in environments with limited activities of free trivalent cations. These results have implications for the fate of catalytic converter-emitted Pt and Pd, and support the need for further Pt and Pd toxicity and bioaccumulation studies. PMID:17328196

Dahlheimer, Susan R; Neal, Clive R; Fein, Jeremy B

2007-02-01

112

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

NASA Astrophysics Data System (ADS)

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.

Yang, Xiufeng; Liu, Moubin; Peng, Shiliu

2014-12-01

113

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

PubMed

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

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

2004-12-01

114

Establishment of Constitutive Model of Titanium Alloy Ti6Al4V and Validation of Finite Element  

Microsoft Academic Search

The quasi-static compressive and dynamic compressive (SHPB) experiments were carried out to investigate the static and dynamic property of titanium alloy Ti6Al4V though analysis and comparison of the experiment results, the Johnson-Cook constitutive model of titanium alloy Ti6Al4V was established. The cutting process of titanium alloy Ti6Al4V was simulated using the orthogonal cutting finite element model. Though the simulation, the

Wu Hong-bing; Xu Chengguang; Jia Zhi-xin; Zhang Xue-chang; Liu Gang

2010-01-01

115

Estimation of the isotope effect on the lattice thermal conductivity of group IV and group III-V semiconductors  

NASA Astrophysics Data System (ADS)

The isotope effect on the lattice thermal conductivity for group IV and group III-V semiconductors is calculated using the Debye-Callaway model modified to include both transverse and longitudinal phonon modes explicitly. The frequency and temperature dependences of the normal and umklapp phonon-scattering rates are kept the same for all compounds. The model requires as adjustable parameters only the longitudinal and transverse phonon Grüneisen constants and the effective sample diameter. The model can quantitatively account for the observed isotope effect in diamond and germanium but not in silicon. The magnitude of the isotope effect is predicted for silicon carbide, boron nitride, and gallium nitride. In the case of boron nitride the predicted increase in the room-temperature thermal conductivity with isotopic enrichment is in excess of 100%. Finally, a more general method of estimating normal phonon-scattering rate coefficients for other types of solids is presented.

Morelli, D. T.; Heremans, J. P.; Slack, G. A.

2002-11-01

116

Group velocity of the light pulse in an open V-type system  

NASA Astrophysics Data System (ADS)

We investigate the group velocity of the probe light pulse in an open V-type system with spontaneously generated coherence. We find that, not only varying the relative phase between the probe and driving pulses can but varying the atomic exit rate or incoherent pumping rate also can manipulate dramatically the group velocity, even make the pulse propagation switching from subluminal to superluminal; the subliminal propagation can be companied with gain or absorption, but the superluminal propagation is always companied with absorption.

Li, Jingjuan; Fan, Xijun; Tian, Shufen; Liu, Chengpu; Gong, Shangqing; Xu, Zhizhan

2007-04-01

117

The metallobiochemistry of ultratrace levels of platinum group elements in the rat.  

PubMed

The use of platinum, palladium and rhodium (Platinum Group Elements - PGEs) and the possibility of exposure to their ultratrace levels is increasing. In fact, the exponential development of metallic PGE-based nanoparticles (<100 nm in size) opens extraordinary perspectives in the areas of electrocatalysts and catalytic converters, magnetic nanopowders, polymer membranes, cancer therapy, coatings, plastics, nanofibres and textiles. Like other metal-based nanoparticles, exposure to PGEs nanoparticles may result in a release of ultratrace amounts of Pt, Pd, Rh ions in the body whose metabolic fate and toxicity still need to be evaluated. Furthermore, PGEs can act as allergic sensitizers by acting as haptens and inducing both type I and IV allergic reactions. In this work we studied the in vivo metabolic patterns of ultratrace levels of potent allergens and sensitizers PGE halogenated salts. (191)Pt, (103)Pd and (101m)Rh radioisotopes were prepared via cyclotron irradiation and used for radiolabelling Na2(191)PtCl4, Na2(103)PdCl4 and Na2(101m)RhCl6 salts. These anionic chlorocomplexes were intraperitoneally injected into rats (114 ng Pt kg(-1) bodyweight; 24 ng Pd kg(-1) b.w.; 16 ng Rh kg(-1) b.w.). At 16 h post-exposure, PGEs were poorly but significantly retained in all tissues analysed. Kidneys, spleen, adrenal gland, liver, pancreas and small intestine were the organs with the highest Pt, Pd, Rh concentrations. In the blood 30-35% of (103)Pd and (191)Pt and 10% of (101m)Rh were recovered in the plasma, mainly bound to albumin and to a less extent to transferrin. The hepatic and renal intracellular distribution showed the highest recovery of (191)Pt, (103)Pd and (101m)Rh in the nuclear fraction (liver) and in the cytosol (kidney). Chromatographic separation and ultrafiltration experiments on kidney and liver cytosols showed the strong ability of biochemical macromolecules to bind (191)Pt, (103)Pd and (101m)Rh, and being responsible for the retention of the three elements in the body. The link to macromolecules is the basis for the sensitizing capacity of PGEs. PMID:25561341

Sabbioni, E; Fortaner, S; Manenti, S; Groppi, F; Bonardi, M; Bosisio, S; Di Gioacchino, M

2015-02-11

118

Coronal Element Abundances of the Post-Common Envelope Binary V471 Tauri with ASCA  

NASA Technical Reports Server (NTRS)

We report on ASCA observations of the coronally active companion star in the post-common envelope binary V471 Tau. While it would be prudent to check the following results with grating spectroscopy, we find that a single-temperature plasma model does not fit the data. Two temperature models with variable abundances indicate that Fe is underabundant compared to the Hyades photospheric mean, whereas, the high first ionization potential element Ne is overabundant. This is indicative of the inverse first ionization effect, believed to result from the fractionation of ionized material by the magnetic field in the upper atmosphere of the star. Evolutionary calculations indicate that there should be no peculiar abundances on the companion star resulting from the common envelope epoch. Indeed, we find no evidence for peculiar abundances, although uncertainties are high.

Still, Martin; Hussain, Gaitee; White, Nicholas E. (Technical Monitor)

2002-01-01

119

Sulfide saturation history of the Stillwater Complex, Montana: chemostratigraphic variation in platinum group elements  

NASA Astrophysics Data System (ADS)

A platinum group element (PGE) investigation of a 5.3 km-thick stratigraphic section of the Stillwater Complex, Montana was undertaken to refine and test a geochemical technique to explore for platiniferous horizons in layered mafic/ultramafic complexes. PGE, Au, major, and trace elements were determined in 92 samples from outcrops along traverses in the Chrome Mountain and Contact Mountain areas in the western part of the Stillwater Complex where the J-M reef occurs ˜1,460 m above the floor of the intrusion. A further 29 samples from a drill hole cored in the immediate vicinity of the J-M reef were analyzed to detail compositional variations directly above and below the J-M reef. Below the J-M reef, background concentrations of Pt (10 ppb) and Pd (7 ppb) are features of peridotites with intermediate S concentrations (mostly 100-200 ppm) and rocks from the Bronzitite, Norite I, and Gabbronorite I zones (mostly <100 ppm S). A sustained increase in S abundance commences at the J-M reef and continues to increase and peaks in the center of the 600 m-thick middle banded series. Over this same interval, Pt, Pd, and Au are initially elevated and then decrease in the order Pd > Pt > Au. Within the middle and upper banded series, S abundances fluctuate considerably, but exhibit an overall upward increase. The behavior of these elements records periodic sulfide saturation during deposition of the Peridotite zone, followed by crystallization under sulfide-undersaturated conditions until saturation is achieved at the base of the J-M reef. Following formation of the reef, sulfide-saturated conditions persisted throughout the deposition of most of the remaining Lower Layered Series. This resulted in a pronounced impoverishment in PGE abundance in the remaining magma, a condition that continued throughout deposition of the remainder of a succession, which is characterized by very low Pt (1.5 ppb) and Pd (0.7 ppb) abundances. Because only unmineralized rock was selected for study in the 5.3 km-thick section, the results provide an unbiased picture of the variation in background PGE levels during crystallization of the Stillwater Complex. In contrast, the variations in the drill core samples through the reef provide a detailed record of ore formation. Plots of Pt, Pd, Pd/S, and Pt + Pd as a function of stratigraphic height in the intrusion show that the location of the J-M reef is defined by an abrupt change in these concentrations and ratios. Although this is the most abrupt change, three other anomalies in PGE abundance and ratios are apparent in the profiles and coincide with known laterally extensive sub-economic sulfide concentrations above the J-M reef. The uppermost of these is the PGE-bearing Picket Pin sulfide horizon. The relative ease with which mineralized horizons can be pinpointed in these diagrams indicates that a similar approach could be used in exploration programs in other ultramafic/mafic intrusions. Our observations exclude the possibilities of either magma mixing within the Stillwater chamber or the fluxing of a volatile-rich fluid as the mechanisms responsible for the genesis of the J-M reef. Rather, our data indicate that the J-M reef formed from a parental magma that was strongly enriched in PGE; this magma likely formed at depth below the Stillwater magma chamber by the interaction of the parental magma with S-rich meta-sedimentary rocks, followed by the re-dissolution of these sulfides in the Stillwater magma.

Keays, Reid R.; Lightfoot, Peter C.; Hamlyn, Paul R.

2012-01-01

120

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

PubMed

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

Wiseman, Clare L S; Zereini, Fathi

2009-04-01

121

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

PubMed

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

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

2009-07-01

122

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

PubMed

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

Li, Pei-Miao; Gao, Xue-Lu

2012-12-01

123

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

PubMed

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

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

2002-04-01

124

Platinum Group Element Preconcentration by NiS Fire-Assay;Suitable for Microbeam Techniques?  

NASA Astrophysics Data System (ADS)

NiS fire assay preconcentration can be used to analyse whole rock for Platinum-Group Elements (PGE) and to prepare matrix matched reference material (RM). For microbeam techniques, the sample must be solid and NiS preconcentration is a technique worth evaluating. Because some techniques such as laser-ablation inductively-coupled-plasma quadrupole-mass-spectrometry (LA-ICP-QMS) do not have sufficently low quantification limits for PGE, preconcentration is necessary. NiS buttons produced at a furnace temperature of 1000o C are not stable for more than a few days (although perfectly suitable for dissolution). XRD spectra show that these buttons contain pentlandite. It exsolves from heazlewoodite and godlevskite and occupy a larger volume than the original phases, thus making the button unstable. Pentlandite formation is a result of the high-sulfur content of the button which improves PGE recovery. Their recovery is a function of the sulfur concentration: the higher the better. If the sulfur content is lowered by increasing the furnace temperature (volatilisation) or recipe modification then the PGE collection lowers dramatically although the button cohesion is stable. The two options are a stable button that does not collect all PGE or an unstable button (not usable for microbeam) fully recovering PGE. In microbeam techniques, sulfide button cannot be used for whole rock PGE determination because a stable and fully PGE recovering button are not possible. Recovery varies for each PGE, althought some PGE might have a complete recovery. A further problem is that during exsolution PGE become inhomogeneously distributed.

Bedard, L. P.

2004-05-01

125

Group analysis of variable coefficient generalized fifth-order KdV equations  

NASA Astrophysics Data System (ADS)

We carry out group analysis of a class of generalized fifth-order Korteweg-de Vries equations with time dependent coefficients. Admissible transformations, Lie symmetries and similarity reductions of equations from the class are classified exhaustively. A criterion of reducibility of variable coefficient fifth-order KdV equations to their constant coefficient counterparts is derived. Some exact solutions are presented.

Kuriksha, O.; Pošta, S.; Vaneeva, O.

2014-12-01

126

SUPPLEMENTAL NUTRITION ASSISTANCE PROGRAM (SNAP) 2013-2014 Academic Year (Tracking Group V2)  

E-print Network

SUPPLEMENTAL NUTRITION ASSISTANCE PROGRAM (SNAP) 2013-2014 Academic Year (Tracking Group V2 (if dependent) household, received benefits from the Supplemental Nutrition Assistance Program or SNAP/we________________________________________________________________________________ received Supplemental Nutrition Assistance Program (SNAP) for year 2011 or 2012. Note: If we have reason

Rosen, Jay

127

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

E-print Network

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

Rosen, Jay

128

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

PubMed

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

Pershina, V; Anton, J

2013-05-01

129

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)

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.

Pershina, V.; Anton, J.

2013-05-01

130

Platinum-group elemental distribution of the Panzhihua layered gabbroic intrusion and associated Fe-Ti oxide ores, SW China  

NASA Astrophysics Data System (ADS)

The Panzhihua intrusion is a 19-km-long layered gabbroic sill hosting a giant magmatic Fe-Ti oxide deposit in the Sichuan Province (SW China). It is synchronous with the formation of the end-Guadalupian (~260 Ma) Emeishan large igneous province. The intrusion consists of a basal microgabbroic Marginal zone (MGZ), overlain in succession by the Lower zone (LZ), Middle zone (sub-zones MZa and MZb) and Upper zone (UZ) composed of gabbroic, oxide gabbroic and/or Fe-Ti oxide cumulates. The ores are confined to the lower part of the intrusion and are particularly well-developed in the MGZ and LZ. This study documents the platinum-group element (PGE) geochemistry of the Panzhihua intrusion in order to examine its mineralization potential with respect to PGE and to understand the role of magnetite in PGE fractionation. We measure the concentrations of PGE (except Os) in 55 samples spanning over a ~1500 m stratigraphic section of the intrusion, following the analytical procedures designed to determine low PGE contents in geological samples Qi et al. (2004, J Anal Atom Spectrom 19, 1335; 2007, Geochem J 41, 407). The weighted average of PGE concentrations over a ~1500 m stratigraphic section of the intrusion is 1.49 ppb Pd, 2.45 ppb Pt, 0.08 ppb Rh, 0.13 ppb Ru and 0.34 ppb Ir. Most rocks of the intrusion are strongly depleted in Pd sub-group PGE (PPGE) compared to coeval high-Ti Emeishan basalts, and have high Cu/Pd ratios (~11800 to 331000; weighted average ~62500). The Fe-Ti oxide ores and some gabbros have elevated S contents and Cu/Zr ratios reflecting the occurrence of cumulus sulfides. These features indicate that the Panzhihua intrusion evolved through S-saturated differentiation and PGE might have been scavenged by early-formed immiscible sulfide liquids from the parental magma. Sulfur saturation was most likely due to early crystallization of Fe-Ti oxides suggested in earlier studies. Future exploration should focus on dykes or staging chambers feeding the intrusion where PGE-rich sulfides were presumably deposited. The MZb rocks, supposed to have formed from a magma that fractionated abundant magnetite to form ores in the underlying zones, do not exhibit strong fractionation between Ir sub-group PGE (IPGE) and PPGE as expected if magnetite preferentially concentrates IPGE. This, together with the lack of correlation between V and IPGE contents in the rocks, imply that magnetite plays a limited role in PGE fractionation.

Pang, K.; Zhou, M.; Qi, L.

2009-12-01

131

Chemical vapor deposition of group IVb, Vb, and VIb elements with nonmetals. A literature review. Information circular  

SciTech Connect

The Bureau of Mines reviewed the chemical vapor deposition (CVD) literature on the nonmetal binary and ternary compounds of the group IVB, VB, and VIB elements, with emphasis directed to the following nonmetals: B, C, N, O, and Si. This review examines each of these binary and selected ternary compounds of the group IVB, VB, and VIB elements as coatings and gives some of their preparative methods, uses, and properties. A total of 259 references were found for these compounds of the nine elements. This review was utilized in the Bureau's research to provide abrasion-, erosion-, and corrosion-resistant coatings in order to conserve critical metals and protect various metallic surfaces in metallurgical, mining, and energy conversion systems.

McDonald, H.O.; Stephenson, J.B.

1983-05-01

132

21 Data Structures for Disjoint Sets Some applications involve grouping n distinct elements into a collection of disjoint  

E-print Network

21 Data Structures for Disjoint Sets Some applications involve grouping n distinct elements by a disjoint-set data structure and presents a simple application. In Section 21.2, we look at a simple linked.1 Disjoint-set operations A disjoint-set data structure maintains a collection S D fS1; S2; : : : ; Skg

133

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

E-print Network

CLINICAL TRIALS OFFICE The principal charge of this focus group was to identify the key elements of a Clinical Trials Office at the LSUHSC-NO Campus. We propose that the mission of the Clinical Trials Office. The Clinical Trials Office will function as a single point-of-contact for all aspects of clinical trials

134

Trace-element concentrations in blood samples from welders of stainless steel or aluminium and a reference group.  

PubMed

The concentrations of 17 trace elements (e.g., copper, cobalt, iron, manganese, chromium, silicon and magnesium) were determined in whole blood samples of 81 persons working with different welding methods on stainless steel or aluminium and 68 nonwelders. Inorganic spark source mass spectrometry was used for the chemical analyses. The data were analyzed by the SIMCA method for pattern recognition (discriminant analysis). No differences were found between the five groups, either in the average levels of the trace elements or in the correlation structures between the trace elements. Thus no blood concentration data on the analyzed elements and collected from a single person contained any information with respect to exposure to the welding fumes investigated. PMID:594726

Ulfvarson, U; Wold, S

1977-12-01

135

Platinum group elements and 187Os/ 188Os in a purported impact ejecta layer near the Eifelian-Givetian stage boundary, Middle Devonian  

NASA Astrophysics Data System (ADS)

A global faunal crisis close to the Eifelian-Givetian stage boundary in the mid-Devonian has been purported to be related to the impact of one or two major extraterrestrial bodies. This was based on unusual mineralogical and chemical features within a distinct composite marl bed, at a level c. 40 cm below the Global Stratotype Section and Point (GSSP) for the Eifelian-Givetian boundary at Jebel Mech Irdane in Morocco. The impact relation has been challenged based partly on the absence of platinum group element data. We present here detailed Ir, Os, Pd and Pt as well as Os isotopic data across the bed at Mech Irdane and from a correlated 10 cm bed at a nearby site, Rich Haroun. Iridium concentrations of 0.13-0.28 ng/g in the beds represent a small enrichment compared to average shale, but Ir/Al ratios are only a factor 1.5-2 higher than background at respective site. Such small enrichments can readily be explained by terrestrial diagenetic processes, and do not require the presence of an extraterrestrial component. On an Al-normalized basis Pd and Pt show weak enrichments, typically a factor 2-4 higher than background. High 187Os/ 188Os ratios, 1.1-3.8, reflect ingrowth of radiogenic Os from Re, which is also evident from Os concentrations of up to 3 ng/g. The platinum group inter-element ratios are clearly non-chondritic. The overall platinum group and trace element (e.g. Co, Ni, As, V) patterns indicate that diagenetic processes at redox fronts have played a crucial role in shaping most element enrichments. If an excess siderophile-rich extraterrestrial component exists in these beds it represents less than 0.2‰ by weight.

Schmitz, Birger; Ellwood, Brooks B.; Peucker-Ehrenbrink, Bernhard; El Hassani, Ahmed; Bultynck, Pierre

2006-09-01

136

Photogrammetry and Laser Scanning for the Earth Sciencesworking Group V6  

NASA Astrophysics Data System (ADS)

With the UK gaining responsibility for Commission V at the Beijing Congress in 2008, there was an opportunity to create a new working group focusing on earth science applications at close range. The earth science community has had a long tradition of using close range photogrammetry, and more recently laser scanning, and such opportunities have not been fully recognised by ISPRS in the past. Formation of a new ISPRS Working Group helps to bridge this gap and promotes the skills of ISPRS members more widely. The purpose of this paper is to justify the creation of Working Group V6 and identify some of the activities conducted over the last four years. In particular, reference will be made to the various technical sessions which have been organised and supported across the world, the first resulting in a Special Issue of The Photogrammetric Record published in September 2010. In addition, Working Group V6 has been responsible for the creation of two freely available guidance documents entitled "tips for the effective use of digital close range photogrammetry and terrestrial laser scanning". The former focuses on close range digital photogrammetry and has developed through several iterations with input from both academic and industrial users from around the world. For this reason it should be of distinct value to new and perhaps non-expert users interested in using photogrammetry for earth science applications. The paper includes a discussion which considers whether the initial four years of activity have been successful. A superficial assessment based upon the number of members attracted worldwide would suggest that this has indeed been the case. A deeper comparison between proposed activities and those actually achieved suggest some discrepancy, which is perhaps inevitable as Working Group Officers clearly have other responsibilities. However, examination of papers published in the earth surface journals reveal high incidence of photogrammetry and laser scanning appearing in recent work. This should encourage members of Working Group V6 in future activities and collaborations.

Chandler, J. H.; Buckley, S. J.; Rieke-Zapp, D.; Wackrow, R.

2012-07-01

137

CSRL-V ENDF/B-V 227-group neutron cross-section library and its application to thermal-reactor and criticality safety benchmarks  

SciTech Connect

Characteristics and contents of the CSRL-V (Criticality Safety Reference Library based on ENDF/B-V data) 227-neutron-group AMPX master and pointwise cross-section libraries are described. Results obtained in using CSRL-V to calculate performance parameters of selected thermal reactor and criticality safety benchmarks are discussed.

Ford, W.E. III; Diggs, B.R.; Knight, J.R.; Greene, N.M.; Petrie, L.M.; Webster, C.C.; Westfall, R.M.; Wright, R.Q.; Williams, M.L.

1982-01-01

138

Platinum group elements in a 3.5 Ga nickel-iron occurrence - Possible evidence of a deep mantle origin  

NASA Technical Reports Server (NTRS)

This paper reports the results of new field observations and the geochemical analyses for the area of the Bon Accord (BA) (the Kaapvaal craton, South Africa) Ni-Fe deposit, with particular consideration given to the trace element, platinum-group element, and isotopic (Pb, Nd, and Os) compositions. On the basis of these data, an interpretation of BA is suggested, according to which the BA deposit is a siderophile-rich heterogeneity remaining in the deep mantle after a process of incomplete core formation. The implications of such a model for the study of core-mantle segregation and the geochemistry of the lowermost mantle are discussed.

Tredoux, Marian; Hart, Rodger J.; Lindsay, Nicholas M.; De Wit, Maarten J.; Armstrong, Richard A.

1989-01-01

139

Structural dependence of the superconducting transition temperature in liquid-quenched alloys based on the group IV B elements  

NASA Astrophysics Data System (ADS)

The structural modifications and superconducting transition temperatures in Ti?Pd, Zr?Pd, Zr?Mo, and Hf?Pd thin-foil alloys (containing up to ˜95 at.% of the group IV B elements) obtained from the liquid state have been investigated. Contrary to some previously reported results, a 'single phase' of the body-centered cubic ? structure cannot be retained in alloys containing more than 90 at.% of the IV B elements at room temperature. The present findings provide a more reliable assessment of the transition temperatures for the cubic ? phase.

Poon, S. J.

1983-08-01

140

Effects of a Low-Element Challenge Course on Abstinence Self-Efficacy and Group Cohesion  

ERIC Educational Resources Information Center

Substance abuse researchers identify self-efficacy and group cohesion as important components in alcohol and other drug-dependency treatment. Objectives: The purpose of this single-group, pretest-posttest study is to explore the therapeutic value of a challenge course intervention on the self-efficacy and group cohesion of nine chemically…

Clem, Jamie M.; Smith, Thomas E.; Richards, Kristin V.

2012-01-01

141

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

SciTech Connect

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.

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

142

Thermo-optical response of layered group-V transition metal dichalcogenides  

Microsoft Academic Search

Summary  In this paper thermoreflectance spectra of group-V transition metal dichalcogenides, both in the visible and in the infra-red,\\u000a are reported and discussed. At temperatures above the onset of the charge density waves (CDW), the results are shown to support\\u000a the assignment of the main structures of interband spectra tod-d transitions, in the framework of the Mattheiss band scheme. At lower

G. Campagnoli; A. Gustinetti; A. Stella; E. Tosatti

1977-01-01

143

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

DOEpatents

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.

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

2001-01-01

144

Finite Element Simulation of Machining of Ti6Al4V Alloy  

SciTech Connect

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.

Rizzuti, S. [Politecnico di Torino, Dept. of Production Systems and Business Economics, Corso Duca degli Abruzzi 24-10129 Torino (Italy); Umbrello, D. [University of Calabria, Dept. of Mechanical Engineering, Ponte Pietro Bucci 45/C-87036 Rende (Italy)

2011-05-04

145

Finite Element Simulation of Machining of Ti6Al4V Alloy  

NASA Astrophysics Data System (ADS)

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.

Rizzuti, S.; Umbrello, D.

2011-05-01

146

Deformation behavior of blended elemental ti-6ai-4v compacts  

NASA Astrophysics Data System (ADS)

A blended elemental Ti-6A1-4V alloy powder, sintered to 99 pct theoretical density, was tested in tension and fatigue and characterized by optical, scanning, and transmission electron microscopy and by X-ray energy dispersive analysis. The microstructure consisted of a combination of equiaxed and low aspect ratio lamellar alpha phase. Two types of pores were observed: macropores at grain boundaries or triple points, and micropores within alpha regions. Chemical homogeneity was achieved within individual alpha or beta regions with slight compositional fluctuations between different grains. The deformation modes in alpha regions were investigated by transmission electron microscopy on thin foils prepared from tensile and cyclically deformed specimens. Tensile deformation occurred by homogeneous slip on both prismatic and pyramidal alpha slip planes. In cyclic deformation, on the other hand, little slip activity was found except for some heterogeneous slip on the basal plane associated with a relatively large micropore. Micropores of ?0.5 ?m size were found to act as dislocation pinning sites.

Welsch, G.; Lee, Y.-T.; Eloff, P. C.; Eylon, D.; Froes, F. H.

1983-03-01

147

Measurement of L x-ray emission from elements in 64 <= Z <= 73 interval stimulated by 59.54 keV photons  

NASA Astrophysics Data System (ADS)

Accurate measurements (mostly within 5%) of L?, L? and L? x-ray emission cross sections were carried out on thick foils of elements lying in 64 <= Z <= 73 interval, stimulated by 59.54 keV photons. They can be of help as an overall reference to compare the theoretical and semi-empirical approaches by which the atomic parameters included in the expressions of L emission cross sections are evaluated. An appropriate extension of the expression linking the cross section to the counting rate measured in reflection geometry on thick targets makes it possible to overcome the difficulties arising from the width in energy of the L? and L? groups and from the jump present in the attenuation coefficients of the target elements within the energy interval of their L? emission lines.

Baraldi, C.; Casnati, E.; Tartari, A.; Singh, B.

2005-08-01

148

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

Microsoft Academic Search

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

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

1996-01-01

149

Environmental risk of particulate and soluble platinum group elements released from gasoline and diesel engine catalytic converters  

Microsoft Academic Search

A comparison of platinum-group element (PGE) emission between gasoline and diesel engine catalytic converters is reported within this work. Whole raw exhaust fumes from four catalysts of three different types were examined during their useful lifetime, from fresh to 80000 km. Two were gasoline engine catalysts (Pt–Pd–Rh and Pd–Rh), while the other two were diesel engine catalysts (Pt). Samples were

M Moldovan; M. A Palacios; M. M Gómez; G Morrison; S Rauch; C McLeod; R Ma; S Caroli; A Alimonti; F Petrucci; B Bocca; P Schramel; M Zischka; C Pettersson; U Wass; M Luna; J. C Saenz; J Santamar??a

2002-01-01

150

The compositional classification of chondrites. V - The Karoonda (CK) group of carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

In the Karoonda, or 'CK' group of carbonaceous chondrites, all normal members are metamorphosed and, while some contain shock veins, all exhibit various degrees of blackening due to fine sulfide and magnetite particle dispersions in silicates. The elemental abundance patterns in CK chondrites are similar to those in CO chondrites, and rather more similar to those in CV chondrites; CK refractory siderophile abundances are intermediate between CV and CO levels. The exceptional abundance of CK chondrites in Antarctica is accounted for in light of the fragmentation of the CK parent objects, which produced a greater proportion of small micrometeoroids.

Kallemeyn, G. W.; Rubin, A. E.; Wasson, J. T.

1991-03-01

151

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

DOEpatents

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.

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

2003-04-08

152

Threat to Valued Elements of Life: The Experience of Dementia across Three Ethnic Groups  

ERIC Educational Resources Information Center

Purpose: There is a fundamental knowledge gap regarding the experience of dementia within minority ethnic groups in the United Kingdom and elsewhere. The present study examined the subjective reality of living with dementia from the perspective of people with dementia within the 3 largest ethnic groups in the United Kingdom. Design and Methods:…

Lawrence, Vanessa; Samsi, Kritika; Banerjee, Sube; Morgan, Craig; Murray, Joanna

2011-01-01

153

Calculations of electron stopping powers for 41 elemental solids over the 50 eV to 30 keV range with the full Penn algorithm  

NASA Astrophysics Data System (ADS)

We present mass collision electron stopping powers (SPs) for 41 elemental solids (Li, Be, graphite, diamond, glassy C, Na, Mg, Al, Si, K, Sc, Ti, V, Cr, Fe, Co, Ni, Cu, Ge, Y, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Cs, Gd, Tb, Dy, Hf, Ta, W, Re, Os, Ir, Pt, Au, and Bi) that were calculated from experimental energy-loss-function data with the full Penn algorithm for electron energies between 50 eV and 30 keV. Improved sets of energy-loss functions were used for 19 solids. Comparisons were made of these SPs with SPs calculated with the single-pole approximation, previous SP calculations, and experimental SPs. Generally satisfactory agreement was found with SPs from the single-pole approximation for energies above 100 eV, with other calculated SPs, and with measured SPs.

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

2012-01-01

154

Combined distillation and normal freezing to purify elements of groups II and VI  

NASA Technical Reports Server (NTRS)

A practical system and its application to the purification of Te and Cd is described. Single crystals are grown directly in vitreous silica ampoules subsequently used for sealed Bridgman growth of (Hg-Cd)Te. The system also prepares the ampoules by heating in high vacuum. Purification of the elements is by the combined effect of distillation and normal freezing. Transport and segregation are discussed.

Holland, L. R.

1984-01-01

155

Cis and trans structures of MO 2 groups in dioxo compounds of metals in groups V, VI, VII, and VIII of the periodic table  

Microsoft Academic Search

UDC 548.736 The structures of dioxo compounds of metals in groups V, VI, VII, and VIII have been examined. It is shown that the tendency for the M-O bonds to be linearly or angularly disposed is determined by the formal valence of the metal. Linear MO 2 groups in transition metal compounds should be realized only when an unshared pair

L. O. Atovmyan; M. A. Porai-Koshits

1970-01-01

156

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

SciTech Connect

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.

Barbee, T.W. Jr.

1981-08-01

157

The group separation of the rare-earth elements and yttrium from geologic materials by cation-exchange chromatography  

USGS Publications Warehouse

Demand is increasing for the determination of the rare-earth elements (REE) and yttrium in geologic materials. Due to their low natural abundance in many materials and the interferences that occur in many methods of determination, a separation procedure utilizing gradient strong-acid cation-exchange chromatography is often used to preconcentrate and isolate these elements from the host-rock matrix. Two separate gradient strong-acid cation-exchange procedures were characterized and the major elements as well as those elements thought to provide the greatest interference for the determination of the REE in geologic materials were tested for separation from the REE. Simultaneous inductively coupled argon plasma-atomic emission spectroscopy (ICAP-AES) measurements were used to construct the chromatograms for the elution studies, allowing the elution patterns of all the elements of interest to be determined in a single fraction of eluent. As a rock matrix, U.S. Geological Survey standard reference BCR-1 basalt was digested using both an acid decomposition procedure and a lithium metaborate fusion. Hydrochloric and nitric acids were tested as eluents and chromatograms were plotted using the ICAP-AES data; and we observed substantial differences in the elution patterns of the REE and as well as in the solution patterns of Ba, Ca, Fe and Sr. The nitric acid elution required substantially less eluent to elute the REE and Y as a group when compared to the hydrochloric acid elution, and provided a clearer separation of the REE from interfering and matrix elements. ?? 1984.

Crock, J.G.; Lichte, F.E.; Wildeman, T.R.

1984-01-01

158

Nuclide production by proton-induced reactions on elements (6 ? Z ? 29) in the energy range from 200 MeV to 400 MeV  

Microsoft Academic Search

In the course of a systematic investigation of integral cross sections for nuclide production by proton-induced reactions, irradiation experiments were carried out with proton energies of 300 and 400 MeV at the Laboratoire National Saturne, Saclay, France using the stacked-foil technique. We included 19 different target elements with atomic numbers between 6 and 79 (C, N, O, Mg, Al, Si,

Th. Schiekel; F. Sudbrock; U. Herpers; M. Gloris; H.-J. Lange; I. Leya; R. Michel; B. Dittrich-Hannen; H.-A. Synal; M. Suter; P. W. Kubik; M. Blann; D. Filges

1996-01-01

159

Phase relations in ternary oxide systems of Group III and VB elements in a subsolidus region. Ternary oxide compounds  

Microsoft Academic Search

Phase relations in the subsolidus region are considered for 54 ternary systems including M2O3-V2O5-R2O5, Y2O3 (La2O3, Sc2O3)-Nb2O5-Ta2O5, M2O3-B2O3-R2O5, M2O3-Ga2O3-R2O5, Al2O3-V2O5-R2O5 (where M is a rare-earth element and R = Ta, Nb). The criteria determining the formation of ternary oxide compounds were found to include the cation sizes and the ratios between the radii of the ions constituting the anionic part

Mikhail G. Zuev

2000-01-01

160

Phase relations in ternary oxide systems of Group III and VB elements in a subsolidus region. Ternary oxide compounds  

Microsoft Academic Search

Phase relations in the subsolidus region are considered for 54 ternary systems including M2O3–V2O5–R2O5, Y2O3 (La2O3, Sc2O3)–Nb2O5–Ta2O5, M2O3–B2O3–R2O5, M2O3–Ga2O3–R2O5, Al2O3–V2O5–R2O5 (where M is a rare-earth element and R = Ta, Nb). The criteria determining the formation of ternary oxide compounds were found to include the cation sizes and the ratios between the radii of the ions constituting the anionic part

Mikhail G Zuev

2000-01-01

161

Common Data Elements for Pediatric Traumatic Brain Injury: Recommendations from the Working Group on Demographics and Clinical Assessment  

PubMed Central

Abstract The Common Data Elements (CDEs) initiative is a National Institutes of Health (NIH) interagency effort to standardize naming, definitions, and data structure for clinical research variables. Comparisons of the results of clinical studies of neurological disorders have been hampered by variability in data coding, definitions, and procedures for sample collection. The CDE project objective is to enable comparison of future clinical trials results in major neurological disorders, including traumatic brain injury (TBI), stroke, multiple sclerosis, and epilepsy. As part of this effort, recommendations for CDEs for research on TBI were developed through a 2009 multi-agency initiative. Following the initial recommendations of the Working Group on Demographics and Clinical Assessment, a separate workgroup developed recommendations on the coding of clinical and demographic variables specific to pediatric TBI studies for subjects younger than 18 years. This article summarizes the selection of measures by the Pediatric TBI Demographics and Clinical Assessment Working Group. The variables are grouped into modules which are grouped into categories. For consistency with other CDE working groups, each variable was classified by priority (core, supplemental, and emerging). Templates were produced to summarize coding formats, guide selection of data points, and provide procedural recommendations. This proposed standardization, together with the products of the other pediatric TBI working groups in imaging, biomarkers, and outcome assessment, will facilitate multi-center studies, comparison of results across studies, and high-quality meta-analyses of individual patient data. PMID:21939389

Adelson, P. David; Pineda, Jose; Bell, Michael J.; Abend, Nicholas S.; Berger, Rachel P.; Giza, Christopher C.; Hotz, Gillian

2012-01-01

162

Comparison between steady-state and dynamic I-V measurements from a single-cell thermionic fuel element  

SciTech Connect

A comparison between steady-state and dynamic I-V measurements from a single-cell thermionic fuel element (TFE) is made. The single-cell TFE used in this study is the prototype for the 40kW{sub e} space nuclear power system that is similar to the 6kW{sub e} TOPAZ-II. The steady-state I-V measurements influence the emitter temperature due to electron cooling. Therefore, to eliminate the steady-state I-V measurement influence on the TFE and provide a better understanding of the behavior of the thermionic energy converter and TFE characteristics, dynamic I-V measurements are made. The dynamic I-V measurements are made at various input power levels, cesium pressures, collector temperatures, and steady-state current levels. From these measurements, it is shown that the dynamic I-V{close_quote}s do not change the TFE characteristics at a given operating point. Also, the evaluation of the collector work function from the dynamic I-V measurements shows that the collector optimization is not due to a minimum in the collector work function but due to an emission optimization. Since the dynamic I-V measurements do not influence the TFE characteristics, it is believed that these measurements can be done at a system level to understand the influence of TFE placement in the reactor as a function of the core thermal distribution. {copyright} {ital 1997 American Institute of Physics.}

Wernsman, B. [New Mexico Engineering Research Institute Thermionics Evaluation Facility 901 University SE Albuquerque, New Mexico87106 (United States)

1997-01-01

163

Comparison between steady-state and dynamic I-V measurements from a single-cell thermionic fuel element  

SciTech Connect

A comparison between steady-state and dynamic I-V measurements from a single-cell thermionic fuel element (TFE) is made. The single-cell TFE used in this study is the prototype for the 40 kW{sub e} space nuclear power system that is similar to the 6 kW{sub e} TOPAZ-II. The steady-state I-V measurements influence the emitter temperature due to electron cooling. Therefore, to eliminate the steady-state I-V measurement influence on the TFE and provide a better understanding of the behavior of the thermionic energy converter and TFE characteristics, dynamic I-V measurements are made. The dynamic I-V measurements are made at various input power levels, cesium pressures, collector temperatures, and steady-state current levels. From these measurements, it is shown that the dynamic I-V's do not change the TFE characteristics at a given operating point. Also, the evaluation of the collector work function from the dynamic I-V measurements shows that the collector optimization is not due to a minimum in the collector work function but due to an emission optimization. Since the dynamic I-V measurements do not influence the TFE characteristics, it is believed that these measurements can be done at a system level to understand the influence of TFE placement in the reactor as a function of the core thermal distribution.

Wernsman, Bernard [New Mexico Engineering Research Institute Thermionics Evaluation Facility 901 University SE Albuquerque, New Mexico 87106 (United States)

1997-01-10

164

Compendation of SSC lattice optics in the presence of dipole field errors: Report of the Correction Element Working Group  

SciTech Connect

The assignment of the Correction Element Working Group (CEWG) is to advance the designs of various candidate correction schemes to a point where they can be compared and distilled down to a single plan. Choosing among, the options often involves consideration of incommensurate factors such as cost, practicality, and theoretical performance. Except for minor issues, the CEWG purpose is to gather and array the facts in a form from which these decisions can be rationally made, but not to make the decisions. The present report analyses various schemes for compensating nonlinear multipole errors in the main arc dipoles of the Superconducting Super Collider. Emphasis is on comparing lumped and distributed compensation, on minimizing the total number of correction elements, and on reducing the sensitivity to closed-orbit errors.

Bintinger, D.; Chao, A.; Forest, E. [and others

1989-02-01

165

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

Microsoft Academic Search

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

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

1991-01-01

166

Optical Modeling of a Holographic Single Element Head-mounted Display Y. Ha, V. Smirnov, L. Glebov, and J.P. Rolland  

E-print Network

Optical Modeling of a Holographic Single Element Head-mounted Display Y. Ha, V. Smirnov, L. Glebov proposed, a single holographic element head-mounted display (HMD) was modeled. Results show that a single element, PTR glass, head-mounted display 1. INTRODUCTION With the rapid development of research in virtual

Glebov, Leon

167

Seeing Double: Multiwavelength Studies of the Remarkable beta Pic Moving Group Member V4046 Sgr  

NASA Astrophysics Data System (ADS)

We are conducting a broad suite of studies targeting the ~20 Myr-old beta Pic Moving Group member V4046 Sgr. The V4046 Sgr system is a hierarchical binary, consisting of a close (2.4-day period) pair of roughly solar-mass (K type) stars and wide (~12 kAU) separation, M-type tertiary (the tertiary itself is also likely a near-equal-mass close binary). The primary pair (V4046 Sgr AB) is orbited by -- and still accreting from -- a large (~350 AU radius), massive, circumbinary molecular disk. Indeed, V4046 Sgr AB represents the oldest and (at D ~ 73 pc) second-nearest known example of such a pre-MS star/disk system (the only specimen closer to Earth is the well-studied TW Hya, which is a single star). We are exploiting the V4046 Sgr system's proximity to examine the structure, composition, and evolutionary state of the (apparently primordial) circumbinary disk orbiting AB, and to search for evidence of recent or ongoing circumbinary planet formation within the disk. Here, we present highlights of results from (a) IR spectroscopy with nearly continuous wavelength coverage from ~1 micron to ~600 microns, obtained with IRTF (SPEX), Spitzer (IRS), and Herschel (PACS and SPIRE); (b) a molecular line survey in the 1 mm band that we conducted with the APEX 12-meter radiotelescope; and (c) near-infrared coronagraphic/polarimetric AO imaging with the new Gemini Planet Imager (GPI), obtained as part of the GPI Early Science campaign.

Rapson, V.; Kastner, J.

2014-09-01

168

Mobilization of the platinum group elements by low-temperature fluids: Implications for mineralization and the iridium controversy  

NASA Technical Reports Server (NTRS)

Geochemical investigations on the widely dispersed Late Proterozoic Acraman impact ejecta horizon and its host marine shales in the Adelaide Geosyncline provide strong evidence for low-temperature mobilization of the platinum group elements (PGE), including Ir. The ejecta horizon was formed when the middle Proterozoic dacitic volcanics in the Gawler Ranges, central South Australia, were impacted by a very large (ca. 4 km) meteorite. The resulting structure, now represented by Lake Acraman, is Australia's largest meteorite impact structure. Debris from the impact was blasted for many hundreds of kilometers, some falling into the shallow sea of the Adelaide Geosyncline, some 300 km to the east of the impact site.

Dowling, Kim; Keays, Reid R.; Wallace, Malcolm W.; Gostin, Victor A.

1992-01-01

169

Average bond energies between boron and elements of the fourth, fifth, sixth, and seventh groups of the periodic table  

NASA Technical Reports Server (NTRS)

The average bond energies D(gm)(B-Z) for boron-containing molecules have been calculated by the Pauling geometric-mean equation. These calculated bond energies are compared with the average bond energies D(exp)(B-Z) obtained from experimental data. The higher values of D(exp)(B-Z) in comparison with D(gm)(B-Z) when Z is an element in the fifth, sixth, or seventh periodic group may be attributed to resonance stabilization or double-bond character.

Altshuller, Aubrey P

1955-01-01

170

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

NASA Astrophysics Data System (ADS)

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 text is devoted to the description of the lattice structural, thermal, elastic, lattice dynamic, electronic energy-band structural, optical and carrier transport properties of these semiconductors. Some corrective effects and related properties, such as piezoelectric, elastooptic and electrooptic properties, are also discussed. The book contains convenient tables summarizing the various material parameters and the definitions of important semiconductor properties. In addition, graphs are included in order to make the information more quantitative and intuitive. The book is intended not only for semiconductor device engineers, but also physicists and physical chemists, and particularly students specializing in the fields of semiconductor synthesis, crystal growth, semiconductor device physics and technology.

Adachi, Sadao

2005-03-01

171

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

NASA Astrophysics Data System (ADS)

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.

Dolph, Melissa Commisso; Santeufemio, Christopher

2014-06-01

172

Cipollone v. Liggett Group, Inc. strengthens federal preemption defense in pesticide tort litigation  

SciTech Connect

When the United States Supreme Court held that the Federal Cigarette Labeling and Advertising Act (Cigarette Act) of 1969 preempted plaintiff`s failure to warn claims in Cipollone v. Liggett Group, Inc., the decision directly affected a far wider range of product liability cases than those involving only cigarettes. This article analyzes how Cipollone affects the defense raised in pesticide injury cases that the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) preempts state common law failure to warn claims. The Eleventh Circuit in Papas v. Upjohn Co. (Papas I), declining to follow contrary authority, held that FIFRA impliedly preempted state law claims that pesticides were inadequately labeled. On a petition for certiorari, the Supreme Court remanded the case back to the Eleventh Circuit for reconsideration in light of Cipollone. Recently, the Eleventh Circuit in Papas v. Upjohn Co. (Papas II) applied Cipollone to hold that FIFRA expressly preempts the state law claims. This article argues that Papas II correctly held, after Cipollone, that FIFRA preempts the state inadequate labeling and failure to warn claims in pesticide cases. 86 refs.

Stevens, R.W. [George Washington Univ. National Law Center, Washington, DC (United States)

1993-12-31

173

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

SciTech Connect

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.

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

1984-01-01

174

The T cell receptor repertoire influences V beta element usage in response to myoglobin  

PubMed Central

T cell clones recognizing the sperm whale myoglobin (SpWMb) epitope 110- 121 in association with H-2d major histocompatibility complex class II molecules display a very limited heterogeneity of T cell receptor (TCR) V beta usage in DBA/2 mice. All clones previously tested used the same V beta 8.2 gene segment and very restricted junctional regions. To investigate the significance of this observation in vivo, we immunized DBA/2 mice with the intact SpW Mb protein or peptide 110-121. Only the V beta 8+ T cells showed any significant response to the 110-121 epitope. The response to peptide 110-121 was then analyzed in mice which, either as a consequence of antibody depletion or through genetic deletion of TCR V beta genes, lacked V beta 8+ peripheral T cells. DBA/2 mice depleted of V beta 8+ T cells by antibody treatment responded poorly to the 110-121 peptide, and only at high antigen concentrations. In contrast, DBA/2V beta a mice (homozygous for a deletion of multiple V beta gene segments including the V beta 8 family) made a response at least as great as that made by DBA/2 mice, even though the DBA/2V beta a mice had a very restricted TCR V beta repertoire compared with DBA/2 mice. Mechanisms which might determine differences in the 110-121 specific response of DBA/2, DBA/2V beta a and F23.1-treated DBA/2 mice are discussed. PMID:2056283

1991-01-01

175

Distribution of platinum-group elements in the Bati Kef chromite deposit, Guleman-Elazig area, eastern Turkey.  

USGS Publications Warehouse

The distribution of platinum-group elements (PGE) within chromite deposits from an ophiolite is determined and their geochemistry compared with chromitites from ophiolites and from stratiform layered complexes elsewhere in the world. The Guleman area chromitites are lenses of layered massive to disseminated chromite in dunite or sheared harzburgite along and near the dunite-harzburgite contact. PGE were analysed by a fire assay/spectrographic method. The analyses, in ppb, varied narrowly near the detection limits; only Ir was mostly detected (24-27 ppb) . The data plot as independent, slight variations of individual PGE with crude and irregular spatial distributions, oriented with respect to the land surface. Based on studies elsewhere, the PGE reside mostly in laurite, erlichmanite and Os/Ir alloys included within or interstitial to chromite. Average values for each PGE were normalized with respect to average chondrite concentrations for these elements. All patterns for ophiolite-chromitites (5) show depletion of these elements relative to chondrite average concentrations, with greater depletion in Pt and Pd than in Ir and Ru, to produce patterns with negative slopes. Chromitites from differentiated stratiform complexes (2) yield patterns with positive slopes. -G.J.N.

Page, N.J.; Engin, T.; Singer, D.A.; Haffty, J.

1984-01-01

176

Physical Conditions and Elemental Abundances in the Symbiotic Novae V1016-CYGNI Hm-Sagittae and HBV:475  

NASA Astrophysics Data System (ADS)

We have obtained optical, near-infrared and UV spectra of the symbiotic stars HM Sge, V 1016 Cyg and HBV 475. We present diagnostic diagrams which indicate that physical conditions vary strongly throughout the symbiotic nebulosities. In HM Sge and V 1016 Cyg we find a steep electron-density gradient covering more than an order of magnitude from the lowest to the highest observed ionization stages. We discuss the formation of hydrogen and helium recombination lines in dense nebulae in order to obtain He abundances. We emphasize that Balmer self-absorption and collisional excitation in He I are important processes in symbiotic nebulae. Their inclusion leads to considerably lower He abundances than previously reported. We obtain He abundances in HM Sge, which are consistent with the solar value. Also in V1016 Cyg and HBV 475 no He overabundance is found although some problems concerning the H I and He I lines remain unsolved. We determine the abundances of C, N, O and Ne in all three objects and additionally Si, Ar and Fe in HM Sge and V1016 Cyg. Compared to solar, nitrogen is enhanced by a factor of 10 in HM Sge and HBV 475 and a factor of 3.5 in V1016 Cyg. The other elements are compatible with solar abundances. The overall abundance pattern found in these symbiotic stars differs markedly from the one observed in nova ejecta. The H and He mass fractions in both HM Sge and V1016 Cyg are 0.72 and 0.25, in contrast to the hydrogen mass fractions ?0.53 observed in novae. We suggest that the material presently constituting these symbiotic nebulae has not undergone nova-processing. The C, N, O abundances in V1016 Cyg are almost identical to the mean abundances observed in M and S giants. HM Sge shows the signs of a more advanced nuclear burning stage and can be interpreted as due to a wind of a highly evolved red giant. We also find no depletion of typical dust constituents like Si and Fe in the D-type symbiotics HM Sge and V1016 Cyg. We conclude that the dust observable in the IR is located outside the ionized nebulosity. We suggest that symbiotic stars can be used to determine elemental abundances in red giants including Miras by means of nebular diagnostic tools. This may be particularly important for poorly known elemental abundances such as He.

Schmid, H. M.; Schild, H.

1990-09-01

177

Fractionation of Platinum Group Elements is not controlled by sulfide/silicate partition coefficients  

NASA Astrophysics Data System (ADS)

The distribution of PGEs between mantle and basaltic melt is well known but poorly understood. The fertile mantle has PGE concentrations of about 0.7 percent of the chondritic values, and the PGE ratios are chondritic (McDonough and Sun, 1995, Chem. Geol. 120, 223--253). In primitive basalts the PGEs are strongly fractionated from each other such that the refractory elements (Os, Ir, Ru) are depleted relative to the less refractory PGEs (Rh, Pt, Pd). We report piston cylinder experiments to understand the physical behaviour of sulfide during partial melting. Fertile mantle material was prepared from finely ground natural mineral separates, doped with different amounts of Fe-Ni-Cu sulfide, and melted in a piston cylinder apparatus at 1350^oC and 0.5 GPa. Nearly all sulfide collects as droplets immersed in interstitial silicate melt pockets at grain boundaries. Droplet sizes are small enough to be washed out of the matrix as "accidental sulfide fraction" when the silicate melt segregates from the matrix. It is the PGE budget of this accidental sulfide fraction that later dominates the absolute PGE content of a basalt at the surface. Our experimental results also indicate that the solidus of monosulfide lies above the solidus of dry, fertile mantle. This implies that crystalline monosulfide solid solution is a stable phase in partially molten upper mantle. The observed PGE ratios in primitive basalts therefore reflect the partitioning of PGEs between monosulfide solid solution and sulfide liquid (Ballhaus et al., 2001, J. Petrol. 42, 1911--1926). During melt segregation, Os, Ir, and Ru remain in the mantle source with the solid residual sulfide, whereas Pt and Pd are washed out along with the accidental sulfide fraction. Neither the absolute nor the relative PGE abundances in basalts are governed by sulfide/silicate partition coefficients.

Bockrath, C.; Holzheid, A.; Ballhaus, C.

2003-04-01

178

Platinum group elements and gold in ferromanganese crusts from Afanasiy-Nikitin seamount, equatorial Indian Ocean: Sources and fractionation  

USGS Publications Warehouse

The major element relationships in ferromanganese (Fe-Mn) crusts from Afanasiy-Nikitin seamount (ANS), eastern equatorial Indian Ocean, appear to be atypical. High positive correlations (r = 0.99) between Mn/Co and Fe/Co ratios, and lack of correlation of those ratios with Co, Ce, and Ce/Co, indicate that the ANS Fe-Mn crusts are distinct from Pacific seamount Fe-Mn crusts, and reflect region-specific chemical characteristics. The platinum group elements (PGE: Ir, Ru, Rh, Pt, and Pd) and Au in ANS Fe-Mn crusts are derived from seawater and are mainly of terrestrial origin, with a minor cosmogenic component. The Ru/Rh (0.5-2) and Pt/Ru ratios (7-28) are closely comparable to ratios in continental basalts, whereas Pd/Ir ratios exhibit values ( 0.75) correlations between water depth and Mn/Co, Fe/Co, Ce/Co, Co, and the PGEs. Fractionation of the PGE-Au from seawater during colloidal precipitation of the major-oxide phases is indicated by well-defined linear positive correlations (r > 0.8) of Co and Ce with Ir, Ru, Rh, and Pt; Au/Co with Mn/Co; and by weak or no correlations of Pd with water depth, Co-normalized major-element ratios, and with the other PGE (r < 0.5). The strong enrichment of Pt (up to 1 ppm) relative to the other PGE and its positive correlations with Ce and Co demonstrate a common link for the high concentrations of all three elements, which likely involves an oxidation reaction on the Mn-oxide and Fe-oxyhydroxide surfaces. The documented fractionation of PGE-Au and their positive association with redox sensitive Co and Ce may have applications in reconstructing past-ocean redox conditions and water masses.

Banakar, V.K.; Hein, J.R.; Rajani, R.P.; Chodankar, A.R.

2007-01-01

179

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

PubMed

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

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

1995-03-01

180

Identification of polycomb and trithorax group responsive elements in the regulatory region of the Drosophila homeotic gene Sex combs reduced  

SciTech Connect

The Drosophilia 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 Polycomb and trithorax group loci. 98 refs., 6 figs., 4 tabs.

Gindhart, J.G. Jr.; Kaufman, T.C. [Indiana Univ., Bloomington, IN (United States)

1995-02-01

181

A study of Venus surface elemental composition from 14 MeV neutron induced gamma ray spectroscopy: Activation analysis  

NASA Astrophysics Data System (ADS)

The surface elemental composition of Venus can be determined using an artificially pulsed 14 MeV neutron generator (PNG) combined with a gamma ray spectrometer (GRS). The 14 MeV neutrons will interact with the surface materials and generate gamma rays, characteristic of specific elements, whose energy spectrum will be measured by GRS. These characteristic gamma rays are produced mainly through 3 different neutron interaction mechanisms: capture, inelastic, and activation reactions. Each reaction type has a different neutron energy dependency and different time scale for gamma ray production and transport. Certain elements are more easily identified through one reaction type over the others. Thus, careful analysis of the gamma ray spectra during and after the neutron pulse provides a comprehensive understanding of the surface elemental composition. In this paper, we use a well-tested neutron/gamma transport code, called Monte Carlo N-Particles (MCNP), to investigate the measurement capability of a PNG-GRS detection system through the neutron activation reactions. An activation analysis was performed for a representative soil composition of Venus with a notional operational scenario of PNG and GRS. The analysis shows that the proposed instrument concept can identify most of the modeled surface elements at Venus with sufficient accuracy through the activation mode. Specifically, U, Th, K, Si can be measured to within 1%, Fe within 2%, Al within 10%, Ca within 5%, Mg with 15%, Mn with 20%, and Cl within 6%. Although modeled in the analysis, it is shown that the activation mode alone cannot distinguish the S and Ti peaks.

Jun, I.; Kim, W.; Smith, M.; Mitrofanov, I.; Litvak, M.

2011-02-01

182

A Study of Venus Surface Elemental Composition From 14-MeV Neutron Induced Gamma Ray Spectroscopy: Activation Analysis  

NASA Astrophysics Data System (ADS)

The surface elemental composition of Venus can be determined by using an artificially pulsed 14 MeV neutron generator (PNG) combined with a gamma ray spectrometer (GRS). The 14 MeV neutrons will interact with the surface materials and generate gamma rays, characteristic of specific elements, whose energy spectrum will be measured by GRS. These characteristic gamma rays are produced mainly through 3 different neutron interaction mechanisms: capture, inelastic, and activation reactions. Each reaction type has a different neutron energy dependency and different time scale for gamma ray production and transport. Certain elements are more easily identified through one reaction type over the others. Thus, careful analysis of the gamma ray spectra during and after the neutron pulse provides a comprehensive understanding of the surface elemental composition. In this paper, we use a well-tested neutron/gamma transport code, called Monte Carlo N-Particles (MCNP), to investigate the measurement capability of a PNG-GRS detection system through the neutron activation reactions. An activation analysis was performed for a representative soil composition of Venus with a notional operational scenario of PNG and GRS. The analysis shows that the proposed instrument concept can identify most of the modeled surface elements at Venus with sufficient accuracy through the activation mode. Specifically, U, Th, K, Si can be measured to within 1%, Fe within 2%, Al within 10%, Ca within 5%, Mg with 15%, Mn with 20%, and Cl within 6%. Although modeled in the analysis, it is shown that the activation mode alone cannot distinguish the S and Ti peaks.

Jun, I.; Kim, W.; Smith, M.; Mitrofanov, I.; Litvak, M. L.

2010-12-01

183

Does common spatial origin promote the auditory grouping of temporally separated signal elements in grey treefrogs?  

PubMed Central

‘Sequential integration’ represents a form of auditory grouping in which temporally separated sounds produced by the same source are perceptually bound together over time into a coherent ‘auditory stream’. In humans, sequential integration plays important roles in music and speech perception. In this study of the grey treefrog (Hyla chrysoscelis), we took advantage of female selectivity for advertisement calls with conspecific pulse rates to investigate common spatial location as a cue for sequential integration. We presented females with two temporally interleaved pulse sequences with pulse rates of 25 pulses/s, which is half the conspecific pulse rate and more similar to that of H. versicolor, a syntopically breeding heterospecific. We tested the hypothesis that common spatial origin between the two pulse sequences would promote their integration into a coherent auditory stream with an attractive conspecific pulse rate. As the spatial separation between the speakers broadcasting the interleaved pulse sequences decreased from 180° to 0°, more females responded and females exhibited shorter response latencies and travelled shorter distances en route to a speaker. However, even in the 180° condition, most females (74%) still responded. Detailed video analyses revealed no evidence to suggest that patterns of female phonotaxis resulted from impaired abilities to localize sound sources in the spatially separated conditions. Together, our results suggest that females were fairly permissive of spatial incoherence between the interleaved pulses sequences and that common spatial origin may be only a relatively weak cue for sequential integration in grey treefrogs. PMID:19727419

Bee, Mark A.; Riemersma, Kasen K.

2008-01-01

184

Investigation of the behavior of platinum-group elements during vitrification of model high-level wastes in application to an induction melter with a cold crucible  

Microsoft Academic Search

Conclusions  In the process of vitrification of high-level wastes the platinum-group elements form at the calcination stage phases which\\u000a have a limited solubility in the glass melts. If the dissolved part of the platinum-group elements, which at 1200–1300C does\\u000a not form more than 30% of their total concentration in the melt [3], is neglected, then apparently it can be assumed that

A. V. Demin; Yu. I. Matyunin

1995-01-01

185

Elements between the IgH variable (V) and diversity (D) clusters influence antisense transcription and lineage-specific V(D)J recombination  

PubMed Central

Ig and T-cell receptor (TCR) variable-region gene exons are assembled from component variable (V), diversity (D) and joining (J) gene segments during early B and T cell development. The RAG1/2 endonuclease initiates V(D)J recombination by introducing DNA double-strand breaks at borders of the germ-line segments. In mice, the Ig heavy-chain (IgH) locus contains, from 5? to 3?, several hundred VH gene segments, 13 D segments, and 4 JH segments within a several megabase region. In developing B cells, IgH variable-region exon assembly is ordered with D to JH rearrangement occurring on both alleles before appendage of a VH segment. Also, IgH VH to DJH rearrangement does not occur in T cells, even though DJH rearrangements occur at low levels. In these contexts, V(D)J recombination is controlled by modulating substrate gene segment accessibility to RAG1/2 activity. To elucidate control elements, we deleted the 100-kb intergenic region that separates the VH and D clusters (generating ?VH-D alleles). In both B and T cells, ?VH-D alleles initiated high-level antisense and, at lower levels, sense transcription from within the downstream D cluster, with antisense transcripts extending into proximal VH segments. In developing T lymphocytes, activated germ-line antisense transcription was accompanied by markedly increased IgH D-to-JH rearrangement and substantial VH to DJH rearrangement of proximal IgH VH segments. Thus, the VH-D intergenic region, and likely elements within it, can influence silencing of sense and antisense germ-line transcription from the IgH D cluster and thereby influence targeting of V(D)J recombination. PMID:21123744

Giallourakis, Cosmas C.; Franklin, Andrew; Guo, Chunguang; Cheng, Hwei-Ling; Yoon, Hye Suk; Gallagher, Michael; Perlot, Thomas; Andzelm, Milena; Murphy, Andrew J.; Macdonald, Lynn E.; Yancopoulos, George D.; Alt, Frederick W.

2010-01-01

186

Finite element analysis of spring-back of V-bending sheet metal forming processes  

Microsoft Academic Search

This paper presents a study of spring-back in the V-bending metal forming process with one clamped end and one free end. Spring-back occurs at the die-lip and V-region of the die model. Different die punch parameters such as punch radius, punch angle and die-lip radius are varied to study their effect on spring-back. Also, the effect of the punch displacement

W. M. Chan; H. I. Chew; H. P. Lee; B. T. Cheok

2004-01-01

187

Penicillin V, loracarbef and clindamycin in tonsillar surface fluid during acute group A streptococcal pharyngotonsillitis.  

PubMed

Patients with acute group A- strepotococcal pharyngotonsillitis were randomly assigned to treatment for 10 d with either phenoxymethylpenicillin (PcV), loracarbef or clindamycin. The concentrations of the drugs, respectively, were determined in tonsillar surface fluid (TSF), serum and the saliva in each patient on altogether 5 occasions; before, during and 4 d after end of therapy. On the same occasions blood was drawn for analysis of C-reactive protein (CRP) and orosomucoid. On the last d of treatment PcV could be detected in TSF in 1 of 6 patients only. Loracarbef had a slower decrease in TSF during therapy and measurable levels did occur 2 d after end of therapy corresponding to MIC 100 for GAS. This may be related to the somewhat better clinical results of the cephalosporins than of PcV, and possibly indicates that an extended therapy with these drugs in primary GAS pharyngotonsillitis for more than the arbitrarily chosen 10 d could reduce the number of recurrent episodes. PcV and loracarbef were not detected in serum after the end of treatment. The concentration of clindamycin in both TSF and the saliva was fairly longstanding during therapy and reached levels exceeding MIC 100 for GAS, in both TSF and serum 2 d after the end of treatment. Several investigations have shown that GAS, especially in the stationary phase may invade respiratory epithelial cells and are present intracellularly in patients with acute pharyngotonsillitis as well as in asymptomatic carriers. The same T-type, identical DNA fingerprints and arbitrarily primed patterns are found in GAS before and after treatment failure indicating that the primary episode and the failures are caused by the same strain. The longstanding concentrations of clindamycin in TSF, roughly independent of the degree of the local inflammation combined with its intracellular accumulation and activity against resting GAS seem to explain the efficiency of the drug in recurrent GAS pharyngotonsillitis. CRP and orosomucoid were of limited value in differing between bacterial and viral pharyngtonsillitis and a correlation between antibiotic concentration and CRP/orosomucoid levels was not found. PMID:16012002

Orrling, Arne; Kamme, Carl; Stjernquist-Desatnik, Anna

2005-01-01

188

Experimental constraints on the partitioning of rhenium and some platinum-group elements between olivine and silicate melt  

NASA Astrophysics Data System (ADS)

We have performed partitioning experiments to assess the role of olivine in controlling the behavior of rhenium and the platinum group elements (PGEs) during basalt petrogenesis. Olivines were crystallized from an iron-bearing basalt at 1 bar (10 5 Pa) and log fO 2 of -2.6, -4.9 and -7.4 (FMQ +4.3, +2 and -0.5, respectively). In situ analyses of olivine and glass by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) reveal a homogeneous distribution of Ru, Rh, Pd, Re, and Pt, but significant Os heterogeneity at the ?m scale. This latter behavior arises from the presence of undissolved Os micronuggets suspended in the melt, and included in olivine crystals. Olivine-melt partition coefficients ( Ds) for Re and the PGEs follow the order: DRh> DRu? DPd˜ DRe˜ DPt. With decreasing fO 2, Rh and Ru become more compatible, with maximum partition coefficients of ˜2.6 and ˜2, respectively, at log fO 2 of -4.9. In contrast, D values for Pd become smaller with decreasing fO 2, to a value of ˜0.006 at log fO 2 of -7.4. Olivine-melt partitioning of Rh, Ru, Pd, Re and Pt derived from our experiments is confirmed by the behavior of these elements in lavas that have evolved by olivine fractionation. An elastic strain model predicts the olivine-melt partitioning of these elements, excepting our measured value of DPt, which is much lower. The fO 2 dependence on partitioning implies that at higher fO 2 some portion of PGEs exist in higher valence states than predicted from their solubility.

Brenan, J. M.; McDonough, W. F.; Dalpé, C.

2003-07-01

189

Anomalous cosmic ray argon and other rare elements at 1-4 MeV/nucleon trapped within the Earth's magnetosphere  

NASA Astrophysics Data System (ADS)

We summarize over 6 years of observations of ~1-4 MeV/nucleon heavy ions trapped in the Earth's magnetosphere on L shells of 1.7-3. We obtained these new results in low Earth orbit with the SAMPEX spacecraft; they extend the observations of trapped heavy ions in this L range to much lower energies than had previously been examined in detail. At 1-4 MeV/nucleon we observed a trapped population with a peak intensity near L~2.3 that includes the anomalous cosmic ray species O, Ne, and Ar also observed in interplanetary space at 1 AU. We also found elements with low first ionization potential (C, Mg-S, and Fe) trapped with the same spatial distribution. The low-energy trapped population increased in intensity between 1996 and 1997, roughly during solar minimum and minimum geomagnetic activity. It is possible that the 1-4 MeV/nucleon trapped population originates from a number of sources, including high-energy trapped anomalous cosmic rays that have lost energy in the residual atmosphere in the case of O and Ne, and directly incident, singly charged anomalous cosmic rays that have become stripped and subsequently trapped in the case of Ar. The group of trapped elements with low first ionization potential (C, Mg-S, and Fe) have roughly solar wind abundances relative to one another, suggesting a possible link between this trapped component and recently discovered solar wind pickup ions released from dust grains within the inner heliosphere.

Mazur, J. E.; Mason, G. M.; Blake, J. B.; Klecker, B.; Leske, R. A.; Looper, M. D.; Mewaldt, R. A.

190

Nuclide production by proton-induced reactions on elements (6 ? Z ? 29) in the energy range from 800 to 2600 MeV  

Microsoft Academic Search

In the course of a systematic investigation of proton-induced reactions for p energies between 800 and 2600 MeV, the target elements O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zr, Rh, Nb, Ba and Au were irradiated with 800 MeV protons at LAMPF\\/Los Alamos National Laboratory, and with 1200, 1600 and 2600 MeV protons at Laboratoire

R. Michel; M. Gloris; H.-J. Lange; I. Leya; M. Lüpke; U. Herpers; B. Dittrich-Hannen; R. Rösel; Th. Schiekel; D. Filges; P. Dragovitsch; M. Suter; H.-J. Hofmann; W. Wölfli; P. W. Kubik; H. Baur; R. Wieler

1995-01-01

191

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

USGS Publications Warehouse

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.

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

1983-01-01

192

Partitioning of platinum-group elements and Au between sulfide liquid and basalt and the origins of mantle-crust fractionation of the chalcophile elements  

NASA Astrophysics Data System (ADS)

The partitioning of platinum-group elements (PGE; Os, Ir, Ru, Rh, Pt, and Pd) and Au between sulfide melt and silicate melt (i.e., DPGEsul) exerts a critical control on the PGE composition of the Earth’s crust and mantle, but previous estimates have been plagued by experimental uncertainties and vary through several orders of magnitude. Here we present direct experimental measurements of DPGEsul, based on in situ microanalysis of the sulfide and silicate melt, with values ranging from ?4 × 105 (Ru) to ?2-3 × 106 (Ir, Pt). Our measurements of DPGEsul are >100 times larger than previous results but smaller than anticipated based on comparison of alloy solubilities in sulfide melts and S-free silicate melts. The presence of S in the silicate melt greatly increases alloy solubility. We use our new set of partition coefficients to develop a fully constrained model of PGE behavior during melting which accurately predicts the abundances of PGE in mantle-derived magmas and their restites, including mid-ocean ridge basalts, continental picrites, and the parental magmas of the Bushveld Complex of South Africa. Our model constrains mid-ocean ridge basalt (MORB) to be the products of pooled low and high degree fractional melts. Within-plate picrites are pooled products of larger degrees of fractional melting in columnar melting regimes. A significant control on PGE fractionation in mantle-derived magmas is exerted by residual alloy or platinum group minerals in their source. At low pressures (e.g., MORB genesis) the mantle residual to partial melting retains primitive mantle inter-element ratios and abundances of PGE until sulfide has been completely dissolved but then evolves to extremely high Pt/Pd and low Pd/Ir because Pt and Ir alloys form in the restite. During melting at high pressure to form picrites or komatiites Ir alloy appears as a restite phase but Pt alloy is not stable due to the large effect of pressure on fS2, and of temperature on fO2 along an internal oxygen buffer, which causes large increases in alloy solubility. The magmas parental to the Bushveld Complex of South Africa appear, at least in part, to be partial melts of mantle that has previously been melted to the point of total sulfide exhaustion at low pressure, closely resembling mantle xenoliths of the Kaapvaal craton. Using the new extremely large DPGEsul the world-class Merensky Reef and UG2 Pt deposits of the Bushveld Complex can readily be modeled as the result of sulfide saturation due to mixing of magmas with unremarkable PGE contents, obviating the need to postulate anomalously PGE-rich parent magmas or hydrothermal inputs to the deposits.

Mungall, James E.; Brenan, James M.

2014-01-01

193

Chemical fractionations in meteorites. V - Volatile and siderophile elements in achondrites and ocean ridge basalts.  

NASA Technical Reports Server (NTRS)

Eighteen achondrites and 4 terrestrial basalts (3 ocean ridge, 1 continental) were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Co, Cs, Cu, Ga, In, Ir, Rb, Se, Tl and Zn. Samples included 7 eucrites, 5 howardites, 2 nakhlites, 2 shergottites, an angrite, and an aubrite. Light and dark portions of the gas-rich meteorites Kapoeta and Pesyanoe were analyzed separately. Nakhlites and shergottites have volatile element abundances similar to those in ocean ridge basalts; eucrites, howardites, and angrites show greater depletions by an order of magnitude and less similar abundance patterns. In terms of a two-component model of planetary accretion, the parent planets contained the following percentages of low-temperature material: eucrites 0.8, nakhlites 38, shergottites 28. Shergottites may be genetically related to L-chondrites. The siderophile element pattern of achondrites resembles that of the moon, but with less extreme depletions.

Laul, J. C.; Keays, R. R.; Ganapathy, R.; Anders, E.; Morgan, J. W.

1972-01-01

194

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

195

Novel Rearrangements in the Staphylococcal Cassette Chromosome Mec Type V Elements of Indian ST772 and ST672 Methicillin Resistant Staphylococcus aureus Strains  

PubMed Central

Staphylococcus aureus is a commensal gram positive bacteria which causes severe and non severe infections in humans and livestock. In India, ST772 is a dominant and ST672 is an emerging clone of Staphylococcus aureus. Both cause serious human diseases, and carry type V SCCmec elements. The objective of this study was to characterize SCCmec type V elements of ST772 and ST672 because the usual PCR methods did not amplify all primers specific to the type. Whole genome sequencing analysis of seven ST772 and one ST672 S. aureus isolates revealed that the SCCmec elements of six of the ST772 isolates were the smallest of the extant type V elements and in addition have several other novel features. Only one ST772 isolate and the ST672 isolate carried bigger SCCmec cassettes which were composites carrying multiple ccrC genes. These cassettes had some similarities to type V SCCmec element from M013 isolate (ST59) from Taiwan in certain aspects. SCCmec elements of all Indian isolates had an inversion of the mec complex, similar to the bovine SCCmec type X. This study reveals that six out of seven ST772 S. aureus isolates have a novel type V (5C2) SCCmec element while one each of ST772 and ST672 isolates have a composite SCCmec type V element (5C2&5) formed by the integration of type V SCCmec into a MSSA carrying a SCC element, in addition to the mec gene complex inversions and extensive recombinations. PMID:24722327

Arakere, Gayathri

2014-01-01

196

Stopping power for low-velocity heavy ions: (0-1.0)MeV\\/nucleon Mg ions in 17 (Z=22-79) elemental solids  

Microsoft Academic Search

The stopping power for 24,26Mg ions in 17 (Z=22-79) elemental solids has been studied in the energy region 0-1.0 MeV\\/nucleon by application of the Doppler-shift attenuation method. At velocities 2v0<v<5v0 (v0 the Bohr velocity), the scaling factors 1.10 (Ti), 0.90 (V), 0.93 (Fe), 0.97 (Co), 0.99 (Ni), 1.03 (Cu), 1.05 (Ge), 1.05 (Nb), 1.15 (Mo), 1.05 (Pd), 1.08 (Ag), 1.09

K. Arstila; J. Keinonen; P. Tikkanen

1990-01-01

197

Functional elements on SIRPalpha IgV domain mediate cell surface binding to CD47.  

PubMed

SIRPalpha and SIRPbeta1, the two major isoforms of the signal regulatory protein (SIRP) family, are co-expressed in human leukocytes but mediate distinct extracellular binding interactions and divergent cell signaling responses. Previous studies have demonstrated that binding of SIRPalpha with CD47, another important cell surface molecule, through the extracellular IgV domain regulates important leukocyte functions including macrophage recognition, leukocyte adhesion and transmigration. Although SIRPbeta1 shares highly homologous extracellular IgV structure with SIRPalpha, it does not bind to CD47. Here, we defined key amino acid residues exclusively expressing in the IgV domain of SIRPalpha, but not SIRPbeta1, which determine the extracellular binding interaction of SIRPalpha to CD47. These key residues include Gln67, a small hydrophobic amino acid (Ala or Val) at the 57th position and Met102. We found that Gln67 and Ala/Val57 are critical. Mutation of either of these residues abates SIRPalpha directly binding to CD47. Functional cell adhesion and leukocyte transmigration assays further demonstrated central roles of Gln67 and Ala/Val57 in SIRPalpha extracellular binding mediated cell interactions and cell migration. Another SIRPalpha-specific residue, Met102, appears to assist SIRPalpha IgV binding through Gln67 and Ala/Val57. An essential role of these amino acid residues in SIRPalpha binding to CD47 was further confirmed by introducing these residues into the SIRPbeta1 IgV domain, which dramatically converts SIRPbeta1 into a CD47-binding molecule. Our results thus revealed the molecular basis by which SIRPalpha binds to CD47 and shed new light into the structural mechanisms of SIRP isoform mediated distinctive extracellular interactions and cellular responses. PMID:17070842

Liu, Yuan; Tong, Qiao; Zhou, Yubin; Lee, Hsiau-Wei; Yang, Jenny J; Bühring, Hans-Jörg; Chen, Yi-Tien; Ha, Binh; Chen, Celia X-J; Yang, Yang; Zen, Ke

2007-01-19

198

Structural and Energetic Analysis of Group V Impurities in p-Type HgCdTe: The Case of As and Sb  

NASA Astrophysics Data System (ADS)

Although molecular beam epitaxy technology-based arsenic-doped Hg1- x Cd x Te has been extensively studied, according to the newly proposed framework of the defect-complex-based p-type doping mechanism, heavier group V elements such as antimony (Sb) should have a different doping behavior because of their larger radius which can cause larger lattice distortion. In this work, we performed first-principles calculations and took As and Sb as examples to study this issue. The substitutional doping, interstitial doping (including split, tetrahedral, and hexagonal interstitial sites), and defect complex doping forms for arsenic and antimony are all investigated. A significant lattice distortion is found in hexagonal and split-site interstitial-Sb-doped Hg0.75Cd0.25Te due to the larger covalent radius of Sb. Compared with As, Sb can lead to a more complicated configuration change in the case of SbHg- V Hg-SbHg tridoping, and the interstitial Sb is found to be stable even with the coupling of Hg vacancies through detailed energetic calculations, indicating that the interstitial Sb has greater ability to form stable defect complexes, and thus great potential to be a more appropriate p-type dopant. This study provides more complementary understanding of the behaviors of group V impurities in HgCdTe.

Wang, Ziyan; Huang, Yan; Lei, Wen; Chen, Xiaoshuang; Zhao, Huxian; Zhou, Xiaohao; Lu, Wei

2014-08-01

199

The shortest period M dwarf eclipsing system BW3 V38. II. Determination of absolute elements  

NASA Astrophysics Data System (ADS)

The spectroscopic data for the short-period (0.1984 deg) eclipsing binary V38, discovered by the OGLE micro-lensing team in Baade's Window field BW3, are analyzed. Radial velocity curves are derived from mid-resolution spectra obtained with EMMI-NTT at ESO - La Silla, and a simultaneous solution of the existing light curve by OGLE and of the new radial velocity curves is obtained. The system is formed by almost twin M3e dwarf components that are very close, but not yet in contact. The spectra of both dwarfs show signatures of the presence of strong chromospheres. Spectroscopy definitely confirms, therefore, what was suggested on the basis of photometry: BW3 V38 is indeed a unique system, as no other similar binary with M components and in such a tight orbit is known. Within the limits posed by the relatively large errors, due to the combined effect of system faintness and of the constraints on exposure time, the derived physical parameters seem to agree with the relations obtained from the other few known eclipsing binaries with late type components (which indicate a discrepancy between the available evolutionary models and the data at ˜10% level). A possible explanation is the presence of strong magnetic fields and fast rotation (that applies to the BW3 V38 case as well). A simple computation of the system secular evolution by angular momentum loss and spin-orbit synchronization shows that the evolution of a system with M dwarf components is rather slow, and indicates as well a possible reason why systems similar to BW3 V38 are so rare. Based on observations collected at the European Southern Observatory, La Silla, Chile.

Maceroni, C.; Montalbán, J.

2004-11-01

200

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

Microsoft Academic Search

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

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

2003-01-01

201

[Effectiveness and tolerance of cefixime in comparison with penicillin V in bacterial pharyngitis and tonsillitis in children. Cefixime Study Group].  

PubMed

154 children aged 2 to 12 years with clinical diagnosis of bacterial pharyngitis and/or tonsillitis and--in most of the patients--a positive enzyme immunoassay for group A beta-hemolytic streptococci before therapy were enrolled in this open controlled randomized and multicenter trial. The children received either 8 mg/kg bodyweight cefixime once daily or 20,000 I.E. pencillin V/kg bodyweight t.i.d. Clinical evaluation and microbiological tests were carried out before treatment and 1-5 days after end of the treatment. 3-4 weeks after end of the treatment the rate of relapses was evaluated. The data of 149 children could be evaluated for clinical efficacy. In the cefixime group 93.3% of the children were cured and 6.7% improved compared to 89.2% and 10.8%, respectively, in the penicillin V group. Complete microbiological data were obtained from 136 patients. The eradication rate was 82.7% in the cefixime group and 77% in the group of patients treated with penicillin V. At follow up relapses were seen in 7 of the cefixime treated patients and in 6 of those receiving penicillin V. Mild side effects were reported by 4 patients in the cefixime group and by 3 children treated with penicillin V (1 drop out each). These results show that cefixime once daily is at least as effective as penicillin V t.i.d. in pharyngitis and tonsillitis in children. Both compounds are well tolerated. PMID:8152203

Adam, D; Hostalek, U

1994-01-01

202

Static and dynamical properties of II-VI and III-V group binary solids  

NASA Astrophysics Data System (ADS)

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 tetrahedrally coordinated semiconductors and ternary chalcopyrites, but can be used for all semiconducting compounds. We have applied an extended formula on ZB structured binary semiconductors and found better agreement with the experimental data as compared to the values evaluated by previous researchers. The bulk modulus and cohesive energy of ZB-type structure compounds exhibit a linear relationship when plotted on a log-log scale against the plasmon energy planck?p (in eV), but fall on a straight line. The results for bulk modulus differ from experimental values by the following amounts: ZnS 0.36%, ZnSe 10%, ZnTe 0.62%, CdS 1.8%, CdSe 7.4% and CdTe 1.6%, AlP 2.6%, AlAs 5.3%, AlSb 4.0%, GaP 0%, AlAs 0%, AlS 4.4%, InP 0%, InAs 0% and InSb 2.1%; and the results for cohesive energy differ from experimental values by the following amounts: ZnS 0.16%, ZnSe 0.73%, ZnTe 0.6%, CdS 7.6%, CdSe 3.5%, CdTe 2.5%, AlP 2.0%, AlAs 3.0%, AlSb 11.1%, GaP 14.6%, AlAs 17.0%, AlSb 8.7%, InP 4.3%, InAs 5.5% and InSb 0.6%.

Yadav, D. S.; Singh, D. V.

2012-01-01

203

Status of the measurement of Cabibbo-Kobayashi-Maskawa Quark-Mixing matrix element V_us from 2003 data from NA48\\/2 experiment at CERN  

Microsoft Academic Search

The sum of the squares of the first row of elements in the Cabibbo-Kobayashi-Maskawa (CKM) Quark Mixing Matrix gives 0.9959±0.0019, indicating a unitarity deviation of 2.2 sigma. This quantity has dominant error contributions from V_us and V_ud. The NA48\\/2 experiment at CERN is measuring V_us from semileptonic decay data of charged kaons taken in 2003. Data from both the semielectronic

Anne Dabrowski

2004-01-01

204

Experimental investigation and 3D finite element prediction of the heat affected zone during laser assisted machining of Ti6Al4V alloy  

Microsoft Academic Search

An experimental study was conducted to characterize the heat affected zone produced when laser heating a Ti6Al4V alloy plate workpiece. The emissivity and absorptivity of the Ti6Al4V alloy were determined experimentally. A 3D transient finite element method for a moving Gaussian laser heat source was developed to predict the depth and width of the heat affected zone on the Ti6Al4V

Jihong Yang; Shoujin Sun; Milan Brandt; Wenyi Yan

2010-01-01

205

"Aegean Seals of the Late Bronze Age: Stylistic Groups, V. Minoan Groups Contemporary with LM IIIA1"  

E-print Network

, Ta Sphragisrrata t()n Khrniorr ([Sibliotirctic tcs cn Athcnris Arclrliolosihcs Hetaircirs no. 7, Athcns lgZZ). l'irri l9fi0 l. l'ini, "l(ypro Agiisclrc I|rllsicgcl,".ll)l 95, I9l.t0, /7 l0ll. t20 Text Nr. I.A1 2 J 4 5 6 7 8 9 10 71 t2 813 14 15 16 18... 19 )a 2'.| 22 23 25 26 27 28 )9 JU 31 Nr. Ref . 32 II -1. r 15 33 II .l.llll, 34 CS .12 r 15 xll 2ri5 J6 Xll 165 37 Vll e(' 38 l8l t9 | Strp1,. lQ(l 40 {+*!"I-re 4l x il .t.r.) 42 Vlll r.r/ 43 ll I ()e 44 Il l l06 45 X ll .r.r/ 46 II 1.,11 V (,/1 il...

Younger, John G.

1986-01-01

206

Hyperinfectivity: A Critical Element in the Ability of V. cholerae to Cause Epidemics?  

PubMed Central

Background Cholera is an ancient disease that continues to cause epidemic and pandemic disease despite ongoing efforts to limit its spread. Mathematical models provide one means of assessing the utility of various proposed interventions. However, cholera models that have been developed to date have had limitations, suggesting that there are basic elements of cholera transmission that we still do not understand. Methods and Findings Recent laboratory findings suggest that passage of Vibrio cholerae O1 Inaba El Tor through the gastrointestinal tract results in a short-lived, hyperinfectious state of the organism that decays in a matter of hours into a state of lower infectiousness. Incorporation of this hyperinfectious state into our disease model provides a much better fit with the observed epidemic pattern of cholera. These findings help to substantiate the clinical relevance of laboratory observations regarding the hyperinfectious state, and underscore the critical importance of human-to-human versus environment-to-human transmission in the generation of epidemic and pandemic disease. Conclusions To have maximal impact on limiting epidemic spread of cholera, interventions should be targeted toward minimizing risk of transmission of the short-lived, hyperinfectious form of toxigenic Vibrio cholerae. The possibility of comparable hyperinfectious states in other major epidemic diseases also needs to be evaluated and, as appropriate, incorporated into models of disease prevention. PMID:16318414

Hartley, David M; Morris, J. Glenn; Smith, David L

2006-01-01

207

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

NASA Astrophysics Data System (ADS)

Fluid and melt inclusions are preserved within pegmatite bodies and cumulus minerals within mafic-ultramafic layered intrusions that host economic concentrations of the platinum-group elements (e.g., Bushveld Complex, South Africa; Stillwater Complex, Montana). The inclusions indicate that the earliest volatile phase to have exsolved from the crystallizing intrusions was a relatively anhydrous carbonic fluid (CO2-dominated). As crystallization proceeded, volatiles became increasingly water-rich and saline, consistent with the relative saturation limits of carbonic and aqueous fluids in mafic silicate liquids, and the partitioning behavior of Cl in fluid-melt systems. Previously unreported, the latest stage volatiles in the layered intrusions were halide melts (slightly hydrous molten salts) of relatively simply composition (NaCl with minor KCl or CaCl2) with salinities in excess of 90 wt% eq. NaCl or CaCl2. These volatiles were trapped at minimum temperatures of 760-800°C, near the eutectic temperature for water-saturated granitic liquid at moderate crustal pressures. Trace element analysis of the salt melt inclusions by laser ablation ICP-MS (ETH Zürich) show that they contain no detectable concentrations of ore and accessory metals. This is in contrast to the earlier, lower salinity volatiles which contain ppm-concentrations of Pt, Pd, As, Bi, Sb as well as abundant S and base metals. Heterogeneous entrapment of late-stage silicate melt and halide melt provides unambiguous evidence for the coexistence of both phases. However, experimental constraints on the nature of exsolved volatiles from mafic or felsic silicate liquids suggest that the halide melt phases cannot represent an exsolved phase from that coexisting silicate liquid, since this would require unrealistically high (initial) Cl:H2O ratios for the parental silicate liquid (> 9 for a granitic residue). Analysis of rhyodacitic silicate melt inclusions that coexist with the halide melt inclusions show that the coeval silicate melts had Cl:H2O ratios of only 0.1 to 0.2. Similarily, the salt melt phases could not have evolved via the removal of H2O by crystallization of hydrous magmatic minerals (e.g., biotite, apatite) since their modal abundances in the intrusions are very low. The most plausible explanation for the halide melt phases involves the "dehydration" of an initially lower- salinity aqueous fluid. This may have occurred by the reaction of the aqueous fluid with nominally-anhydrous minerals such as pyroxene, or by the late-stage alteration of cumulus minerals to hydrous mineral assemblages. Through the use of conventional hydrothermal experimental techniques, it can be shown that the reaction of a volumetrically-minor CaCl2-rich aqueous fluid phase (20 wt% eq. CaCl2) with the assemblage diopside-enstatite-quartz at near-solidus conditions (700°C, 0.4 kbar) results in the formation of tremolite by the reaction of H2O with the initially anhydrous mafic mineral assemblage. The resulting salinity of the dehydrated saline phase, trapped as synthetic inclusions in quartz, was > 96 wt% eq. CaCl2, consistent with the water-poor nature of the salt melt inclusions from the intrusions. The results of this study indicate that, through the loss of H2O, metal-bearing aqueous volatiles in layered intrusions may precipitate metals as they are dehydrated to form salt melt phases. Metal precipitation may occur as amount of free H2O in the volatile phase necessary to hydrate metal complexes decreases. This precipitation mechanism challenges the conventional magmatic hypothesis for platinum-group element deposit formation in layered intrusions.

Hanley, J. J.

2007-12-01

208

Red/near-infrared luminescence tuning of group-14 element complexes of dipyrrins based on a central atom.  

PubMed

A dipyrrin complex has been one of the most utilized fluorescent dyes, and a variety of dipyrrin complexes show intriguing functions based on the various coordination structures of the central element. We now report the synthesis, structure, and photophysical properties of germanium and stannane complexes of the N2O2-type tetradentate dipyrrin, L·Ge and L·Sn, which are heavier analogues of the previously reported dipyrrin silicon complex, L·Si. The central group-14 atoms of the monomeric complexes have geometries close to trigonal bipyramidal (TBP), in which the contribution of the square-pyramidal (SP) character becomes higher as the central atom is heavier. Interestingly, L·Sn formed a dimeric structure in the crystal. All complexes L·Si, L·Ge, and L·Sn showed a fluorescence in the red/NIR region. Fluorescence quantum yields of L·Ge and L·Sn are higher than that of L·Si. These results indicated that the central atom on the dipyrrin complexes contributes not only to the geometry difference but also to tuning the fluorescence properties. PMID:24422462

Yamamura, Masaki; Albrecht, Marcel; Albrecht, Markus; Nishimura, Yoshinobu; Arai, Tatsuo; Nabeshima, Tatsuya

2014-02-01

209

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

NASA Astrophysics Data System (ADS)

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 reinforce the conclusion that the radiogenic 186Os/188Os compositions of these PGE alloys are very difficult to reconcile with a derivation of their Os from the outer core. Such a model requires extremely early growth of the inner core to its present size, within several hundred million years after accretion of the Earth, which is geophysically implausible. Collectively, our data suggest instead that partial melting or metasomatic processes in the upper mantle play a primary role in controlling the Os isotopic systematics of these Os-rich PGE alloys and suggest the existence of upper mantle components characterized by radiogenic 186Os/188Os ratios. Pyroxene-rich lithologies are possible candidates.

Meibom, Anders; Frei, Robert; Sleep, Norman H.

2004-02-01

210

The effects of group-I elements co-doping with Mn in ZnO dilute magnetic semiconductor  

NASA Astrophysics Data System (ADS)

Mn-Li codoped ZnO (Zn(Mn,Li)O), Mn-Na codoped ZnO (Zn(Mn,Na)O), and Mn-K codoped ZnO (Zn(Mn,K)O) thin films were deposited on quartz substrates by pulsed laser deposition. The doping effects of group-I elements (e.g., Li, Na, and K) on the structural, magnetic, and optical properties of the Mn doped ZnO (ZnMnO) films were discussed. X-ray diffraction and K-edge x-ray absorption near-edge structure measurements revealed that all the films showed a hexagonal wurtzite ZnO structure, and no other clusters, precipitates, or second phases were detected. Zn(Mn,Na)O and Zn(Mn,Li)O films showed a weak p-type conductivity, while the Zn(Mn,K)O film appeared a highly resistivity. The saturation magnetization of Zn(Mn,Na)O and Zn(Mn,Li)O films was 1.2 and 0.18 ?B/Mn, respectively. The hole-related defects, induced by doping with a low content of Li or Na, contributed to the room temperature ferromagnetism in the ZnMnO system.

Zhang, Liqiang; Zhang, Yinzhu; Ye, Zhizhen; Lu, Jianguo; Lu, Bin; He, Bo

2012-06-01

211

Platinum group element enrichments and possible chondritic Ru:Ir across the Frasnian-Famennian boundary, western New York State.  

PubMed

The Frasnian-Famennian boundary is recognized as the culmination of a global mass extinction in the Late Devonian. In western New York State the boundary is a distinct horizon within a pyritic black shale bed of the upper Hanover Shale defined by the first occurrence of Palmatolepis triangularis in the absence of Frasnian conodonts. The boundary is characterized by a minor disconformity marked by a lag concentration of conodonts. Iridium at the boundary is 0.11-0.24 ng/g, two to five times background levels of <0.05 ng/g; other Ir enrichments of 0.38 ng/g and 0.49 ng/g occur within 50 cm of the conodont-constrained boundary. Numerous Ir enrichments in the boundary interval suggest extraterrestrial accretion and platinum group element (PGE) concentration at disconformities, or mobilization and concentration in organic-rich/pyritic-rich laminations from cosmic or terrestrial sources. PGE ratios of Pt/Pd and Ku/Ir at the boundary horizon approximate chondritic ratios and are suggestive of an unaltered extraterrestrial source. These values do not conclusively establish a single extraterrestrial impact as the ultimate cause of the Frasnian-Famennian mass extinction, especially given the presence of similar Ir enrichments elsewhere in the section and the absence at the boundary of microtektites and shocked mineral grains. PMID:11541728

Over, D J; Conaway, C A; Katz, D J; Goodfellow, W D; Gregoire, D C

1997-08-01

212

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

NASA Astrophysics Data System (ADS)

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.

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

213

Alpha spectroscopy of nuclides produced in the interaction of 5 GeV protons with heavy element targets  

NASA Astrophysics Data System (ADS)

Alpha particle energies were redetermined to an accuracy of 2 to 5 keV for a group of 40 neutron-deficient nuclides with atomic numbers ranging from 65 to 88. Improved half-life values were measured for 10 of these nuclides. Weightless samples containing mixtures of these activities were prepared by use of the helium jet transport technique to remove spallation and fragmentation products recoiling from targets of U, Th, Au, and Ta bombarded with 5 GeV protons. Experimental and calibration techniques are discussed in detail. Implications of the results for the mechanism of reaction of 5 GeV protons with complex targets are briefly discussed. RADIOACTIVITY 5 GeV p + U, Th, Au, Ta; separated recoil products by helium jet; measured E?, t12 151Dy, 154Er, 150Dy, 152Ho, 152Hom, 151Ho, 151Hom, 153Er, 152Er, 154Tm, 154Tmm, 153Tm, 179Pt, 155Yb, 178Pt, 177Pt, 176Pt, 199Pom, 198Po, 212Fr, 197Pom, 213Fr, 212Ra; measured E? 149Tb, 211At, 204Fr, 222Ac, 217At, 218Rn, 219Fr, 211Po, 214Po, 217Rn, 216At, 218Fr, 215At, 213Po, 212Po, 214At, 211Pom; reaction mechanisms discussed.

Bowman, J. David; Eppley, Richard E.; Hyde, Earl K.

1982-02-01

214

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

PubMed

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 VHs, separated by an intergenic region from Igh Ds, JHs, 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 VH-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 VH use. IGCR1 functions in all these regulatory contexts by suppressing predominant rearrangement of D-proximal VHs. 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

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

2015-02-10

215

A database of chondrite analyses including platinum group elements, Ni, Co, Au, and Cr: Implications for the identification of chondritic projectiles  

NASA Astrophysics Data System (ADS)

Siderophile elements have been used to constrain projectile compositions in terrestrial and lunar impact melt rocks. To obtain a better knowledge of compositional differences between potential chondritic projectile types, meteorite analyses of the elements Ru, Rh, Pd, Os, Ir, Pt, Cr, Co, Ni, and Au were gathered into a database. The presented compilation comprises 806 analyses of 278 chondrites including new ICP-MS analyses of Allende and two ordinary chondrites. Each data set was evaluated by comparing element ratios of meteorites from the same chondrite group. Characteristic element abundances and ratios were determined for each group. Features observed in the element abundance patterns can be linked directly to the presence of certain components, such as the abundance of refractory elements Os, Ir, and Ru correlating with the occurrence of refractory inclusions in CV, CO, CK, and CM chondrites. The refined characteristic element ratios appear to be representative not only for meteorites, but also for related asteroidal bodies. Chondrite element ratios were compared to previously published values from impact melt rocks of the Popigai and Morokweng impact structures confirming that an identification of the specific type of projectile (L and LL chondrite, respectively) is possible. The assessment for Morokweng is supported by the recent discovery of an LL chondrite fragment in the impact melt rocks. Ultimately, the database provides valuable information for understanding processes in the solar nebula as they are recorded in chondrites. A new type of complementarity between element patterns of CK and EH chondrites is suggested to be the result of condensation, redox, and transportation processes in the solar nebula.

Tagle, Roald; Berlin, Jana

2008-03-01

216

BRAF-V600E expression in precursor versus differentiated dendritic cells defines clinically distinct LCH risk groups  

PubMed Central

Langerhans cell histiocytosis (LCH) is a clonal disorder with elusive etiology, characterized by the accumulation of CD207+ dendritic cells (DCs) in inflammatory lesions. Recurrent BRAF-V600E mutations have been reported in LCH. In this study, lesions from 100 patients were genotyped, and 64% carried the BRAF-V600E mutation within infiltrating CD207+ DCs. BRAF-V600E expression in tissue DCs did not define specific clinical risk groups but was associated with increased risk of recurrence. Strikingly, we found that patients with active, high-risk LCH also carried BRAF-V600E in circulating CD11c+ and CD14+ fractions and in bone marrow (BM) CD34+ hematopoietic cell progenitors, whereas the mutation was restricted to lesional CD207+ DC in low-risk LCH patients. Importantly, BRAF-V600E expression in DCs was sufficient to drive LCH-like disease in mice. Consistent with our findings in humans, expression of BRAF-V600E in BM DC progenitors recapitulated many features of the human high-risk LCH, whereas BRAF-V600E expression in differentiated DCs more closely resembled low-risk LCH. We therefore propose classification of LCH as a myeloid neoplasia and hypothesize that high-risk LCH arises from somatic mutation of a hematopoietic progenitor, whereas low-risk disease arises from somatic mutation of tissue-restricted precursor DCs. PMID:24638167

Berres, Marie-Luise; Lim, Karen Phaik Har; Peters, Tricia; Price, Jeremy; Takizawa, Hitoshi; Salmon, Hélène; Idoyaga, Juliana; Ruzo, Albert; Lupo, Philip J.; Hicks, M. John; Shih, Albert; Simko, Stephen J.; Abhyankar, Harshal; Chakraborty, Rikhia; Leboeuf, Marylene; Beltrão, Monique; Lira, Sérgio A.; Heym, Kenneth M.; Clausen, Björn E.; Bigley, Venetia; Collin, Matthew; Manz, Markus G.; McClain, Kenneth

2014-01-01

217

Deletion of the P5abc Peripheral Element Accelerates Early and Late Folding Steps of the Tetrahymena Group I Ribozyme  

SciTech Connect

The P5abc peripheral element stabilizes the Tetrahymena group I ribozyme and enhances its catalytic activity. Despite its beneficial effects on the native structure, prior studies have shown that early formation of P5abc structure during folding can slow later folding steps. Here we use a P5abc deletion variant (E{sup {Delta}P5abc}) to systematically probe the role of P5abc throughout tertiary folding. Time-resolved hydroxyl radical footprinting shows that E{sup {Delta}P5abc} forms its earliest stable tertiary structure on the millisecond time scale, {approx}5-fold faster than the wild-type ribozyme, and stable structure spreads throughout E{sup {Delta}P5abc} in seconds. Nevertheless, activity measurements show that the earliest detectable formation of native E{sup {Delta}P5abc} ribozyme is much slower ({approx}0.6 min{sup -1}), in a manner similar to that of the wild type. Also similar, only a small fraction of E{sup {Delta}P5abc} attains the native state on this time scale under standard conditions at 25 {sup o}C, whereas the remainder misfolds; footprinting experiments show that the misfolded conformer shares structural features with the long-lived misfolded conformer of the wild-type ribozyme. Thus, P5abc does not have a large overall effect on the rate-limiting step(s) along this pathway. However, once misfolded, E{sup {Delta}P5abc} refolds to the native state 80-fold faster than the wild-type ribozyme and is less accelerated by urea, indicating that P5abc stabilizes the misfolded structure relative to the less-ordered transition state for refolding. Together, the results suggest that, under these conditions, even the earliest tertiary folding intermediates of the wild-type ribozyme represent misfolded species and that P5abc is principally a liability during the tertiary folding process.

Russell,R.; Tijerina, P.; Chadee, A.; Bhaskaran, H.

2007-01-01

218

A redshift survey of IRAS galaxies. V - The acceleration on the Local Group  

NASA Technical Reports Server (NTRS)

The acceleration on the Local Group is calculated based on a full-sky redshift survey of 5288 galaxies detected by IRAS. A formalism is developed to compute the distribution function of the IRAS acceleration for a given power spectrum of initial perturbations. The computed acceleration on the Local Group points 18-28 deg from the direction of the Local Group peculiar velocity vector. The data suggest that the CMB dipole is indeed due to the motion of the Local Group, that this motion is gravitationally induced, and that the distribution of IRAS galaxies on large scales is related to that of dark matter by a simple linear biasing model.

Strauss, Michael A.; Yahil, Amos; Davis, Marc; Huchra, John P.; Fisher, Karl

1992-01-01

219

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

E-print Network

, 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

Vonessen, Nikolaus

220

Structure of the type IX group B Streptococcus capsular polysaccharide and its evolutionary relationship with types V and VII.  

PubMed

The Group B Streptococcus capsular polysaccharide type IX was isolated and purified, and the structure of its repeating unit was determined. Type IX capsule ? 4)[NeupNAc-?-(2 ? 3)-Galp-?-(1 ? 4)-GlcpNAc-?-(1 ? 6)]-?-GlcpNAc-(1 ? 4)-?-Galp-(1 ? 4)-?-Glcp-(1 ? appears most similar to types VII and V, although it contains two GlcpNAc residues. Genetic analysis identified differences in cpsM, cpsO, and cpsI gene sequences as responsible for the differentiation between the three capsular polysaccharide types, leading us to hypothesize that type V emerged from a recombination event in a type IX background. PMID:24990951

Berti, Francesco; Campisi, Edmondo; Toniolo, Chiara; Morelli, Laura; Crotti, Stefano; Rosini, Roberto; Romano, Maria Rosaria; Pinto, Vittoria; Brogioni, Barbara; Torricelli, Giulia; Janulczyk, Robert; Grandi, Guido; Margarit, Immaculada

2014-08-22

221

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)  

Microsoft Academic Search

Inductively coupled plasma-mass spectrometry coupled with cation exchange matrix separation has been optimised for the direct\\u000a determination of platinum group element (PGE) and trace element emissions from a diesel engine car. After matrix separation\\u000a 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

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

2011-01-01

222

Poisson-Lie group of pseudodifferential symbols and fractional KP-KdV hierarchies  

Microsoft Academic Search

The Lie algebra of pseudodifferential symbols on the circle has a nontrivial central extension (by the ``logarithmic'' 2-cocycle) generalizing the Virasoro algebra. The corresponding extended subalgebra of integral operators generates the Lie group of classical symbols of all real (or complex) degrees. It turns out that this group has a natural Poisson-Lie structure whose restriction to differential operators of an

Boris Khesin; Ilya Zakharevich

1993-01-01

223

Experiments and finite element simulations on micro-milling of Ti6Al4V alloy with uncoated and cBN coated micro-tools  

E-print Network

Experiments and finite element simulations on micro-milling of Ti­6Al­4V alloy with uncoated and c performance in micro-milling is considered challenging. The titanium alloy Ti­6Al­4V offers superb strength with the reactivity of titanium (Ti) with tool materials and resultant burr formation [7]. In micro-milling, fine

Ozel, Tugrul

224

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

SciTech Connect

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.

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

225

Positive anomaly in platinum group elements and the presence of shocked diamonds: Two question marks at the Younger Dryas  

NASA Astrophysics Data System (ADS)

Recently, a large size impact was proposed as the cause of the global changes taking place at the Younger Dryas (YD) some 12,9 kyr ago. Impact evidence was reported in a C-rich black layer of broad geographic distribution. The impact markers consist of a large anomaly in the concentration of platinum group elements (PGE) and the presence of nanodiamonds, in particular lonsdaleite, which hexagonal structure is believed to be of shock origin. The impact is proposed to have occurred on the North American continent. A crater large enough (> 150 km) to induce a mass extinction some ~12.9 ka ago, formed in a geologically well-known area, is unlikely to have escaped detection. Therefore, an alternative hypothesis is that a cometary projectile exploded fully within the atmosphere spreading PGE and shock formed diamonds, without any target rock contribution, all around the Northern hemisphere. So far, PGE measurements failed to reproduce the elevated (> ppb) concentrations reported previously at Younger Dryas sites containing the black layer. In Lommel (Belgium) where the first study detected up to 117 ppb Ir, the Ir concentration is below the detection limit of the method (NiS fire assay + ICP-MS) used (0.06 ppb). At all sites analyzed the PGE pattern is typical of that of the continental crust. In several craters (Popigai, Ries) or at the KT boundary nanodiamonds have been reported associated with shocked materials. Several types of carbon components occur in the black layer of the Lommel section such as i) flakes reaching up to 1 µm, ii) nano particles of cubic diamond, 1 to 10 nm in size and iii) larger carbon onion-ring structures, which core can act as a nanoscopic pressure cell leading to the formation of nanodiamond by self- compression. The Lommel nanodiamonds present in the Younger Dryas layer do resemble nanodiamonds found in carbon spherules of unknown origin previously reported in top soil from several localities in Belgium and Germany. The C stable isotopic signature measured in the C-rich black layer is clearly produced by organic matter of terrestrial origin (-29‰).

Claeys, P. F.; Schryvers, D.; Tian, H.; Goderis, S.

2009-12-01

226

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

Microsoft Academic Search

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

Xiaoping Zheng; Xiaocui Wang; Tingkuan Zhong

2010-01-01

227

Photoionization cross sections for the trans-iron element Se+ from 18 to 31 eV  

NASA Astrophysics Data System (ADS)

Absolute photoionization cross-section calculations are presented for Se+ using large-scale close-coupling calculations within the Breit-Pauli and Dirac-Coulomb R-matrix approximations. The results from our theoretical work are compared with recent measurements (Esteves 2010 PhD Thesis publication number AAI3404727, University of Reno, NV, USA; Sterling et al 2011 J. Phys. B: At. Mol. Opt. Phys. 44 025701; Esteves et al 2011 Phys. Rev. A 84 013406) made at the advanced light source (ALS) radiation facility in Berkeley, CA, USA. We report on results for the photon energy range 18.0-31.0 eV, which spans the ionization thresholds of the 4So3/2 ground state and the low-lying 2Do5/2,3/2 and 2Po3/2,1/2 metastable states. Metastable fractions are inferred from our present work. Resonance energies and quantum defects of the prominent Rydberg resonances series identified in the spectra are compared for the 4p ? nd transitions with the recent ALS experimental measurements made on this complex trans-iron element.

McLaughlin, B. M.; Ballance, C. P.

2012-05-01

228

Effect of isothermal forging on microstructure and fatigue behavior of blended elemental Ti-6Al-4V powder compacts  

NASA Astrophysics Data System (ADS)

The effect of isothermal hot forging (IHF) on microstructure, pore closure, and tensile and fatigue properties of Ti-6A1-4V blended elemental cold pressed and sintered powder compacts was investigated. Two types of sponge fines were used: (a) high chloride produced by the Hunter sodium reduction process (HP) and (b) low chloride produced by the electrolytic process (EP). The as-sintered HP compacts were 99 pct dense while the EP compacts were only 92 pct dense. All sintered preforms were isothermally hot forged below the beta transus temperature and reached almost full density. The microstructure of the HP forged compacts consisted of fine equiaxed alpha, while the EP forged compacts exhibited a coarse lenticular alpha structure after 30 pct reduction and a partially recrystallized structure after 68 pct reduction. It was found that EP compacts forged to a 30 pct reduction exhibited a low fatigue limit of 172 MPa (25 ksi), since the lenticular alpha morphology and the residual porosity resulted in premature fatigue crack initiation. On the other hand, a higher fatigue strength of 485 MPa (70 ksi) was obtained for EP compacts forged to a 78 pct reduction due to the mixed equiaxed/lenticular alpha morphology as well as removal of stress concentration features such as interparticle pore interfaces.

Weiss, I.; Eylon, D.; Toaz, M. W.; Froes, F. H.

1986-03-01

229

Effect of isothermal forging on microstructure and fatigue behavior of blended elemental Ti-6Al-4V powder compacts  

SciTech Connect

The effect of isothermal hot forging (IHF) on microstructure, pore closure, and tensile and fatigue properties of Ti-6Al-4V blended elemental cold pressed and sintered powder compacts was investigated. Two types of sponge fines were used: (1) chloride produced by the Hunter sodium reduction process (HP) and (2) low chloride produced by the electrolytic process (EP). The as-sintered HP compacts were 99 pct dense while the EP compacts were only 92 pct dense. All sintered preforms were isothermally hot forged below the beta transus temperature and reacted almost full density. The microstructure of the HP forged compacts consisted of fine equiaxed alpha, while the EP forged compacts exhibited a coarse lenticular alpha structure after 30 pct reduction and a partially recrystallized structure after 68 pct reduction. It was found that EP compacts forged to a 30 pct reduction exhibited a low fatigue limit of 172 MPa (25 ksi), since the lenticular alpha morphology and the residual porosity resulted in premature fatigue crack initiation. On the other hand, a higher fatigue strength of 485 MPa (70 ksi) was obtained for EP compacts forged to a 78 pct reduction due to the mixed equiaxed/lenticular alpha morphology as well as removal of stress concentration features such as interparticle pore interfaces. 26 references.

Weiss, I.; Eylon, D.; Toaz, M.W.; Froes, F.H.

1986-03-01

230

Three groups of transposable elements with contrasting copy number dynamics and host responses in the maize (Zea mays ssp. mays) genome.  

PubMed

Most angiosperm nuclear DNA is repetitive and derived from silenced transposable elements (TEs). TE silencing requires substantial resources from the plant host, including the production of small interfering RNAs (siRNAs). Thus, the interaction between TEs and siRNAs is a critical aspect of both the function and the evolution of plant genomes. Yet the co-evolutionary dynamics between these two entities remain poorly characterized. Here we studied the organization of TEs within the maize (Zea mays ssp mays) genome, documenting that TEs fall within three groups based on the class and copy numbers. These groups included DNA elements, low copy RNA elements and higher copy RNA elements. The three groups varied statistically in characteristics that included length, location, age, siRNA expression and 24:22 nucleotide (nt) siRNA targeting ratios. In addition, the low copy retroelements encompassed a set of TEs that had previously been shown to decrease expression within a 24 nt siRNA biogenesis mutant (mop1). To investigate the evolutionary dynamics of the three groups, we estimated their abundance in two landraces, one with a genome similar in size to that of the maize reference and the other with a 30% larger genome. For all three accessions, we assessed TE abundance as well as 22 nt and 24 nt siRNA content within leaves. The high copy number retroelements are under targeted similarly by siRNAs among accessions, appear to be born of a rapid bust of activity, and may be currently transpositionally dead or limited. In contrast, the lower copy number group of retrolements are targeted more dynamically and have had a long and ongoing history of transposition in the maize genome. PMID:24743518

Diez, Concepcion M; Meca, Esteban; Tenaillon, Maud I; Gaut, Brandon S

2014-04-01

231

A trial of family therapy v. a relatives group for schizophrenia.  

PubMed

Schizophrenic patients living in high contact with relatives having high expressed emotion (EE) were recruited for a trial of social interventions. The patients were maintained on neuroleptic medication, while their families were randomly assigned to education plus family therapy or education plus a relatives group. Eleven out of 12 families accepted family therapy in the home, whereas only six out of 11 families were compliant with the relatives group. Non-compliance was associated with a poorer outcome for the patients in terms of the relapse rate. The relapse rate over nine months in the family therapy stream was 8%, while that in compliant families in the relatives group stream was 17%. Patients' social functioning showed small, non-significant, gains. The data from the current trial were compared with data from a previous trial. The lowering of the relapse rate in schizophrenia appears to be mediated by reductions in relatives' EE and/or face-to-face contact, and is not explained by better compliance with medication. Reduction in EE and/or contact was associated with a minuscule relapse rate (5%). Very little change occurred in families who were non-compliant with the relatives group. On the basis of these findings, we recommend that the most cost-effective procedure is to establish relatives groups in conjunction with family education and one or more initial family therapy sessions in the home. It is particularly important to offer home visits to families who are unable to or refuse to attend the relatives groups. PMID:2673479

Leff, J; Berkowitz, R; Shavit, N; Strachan, A; Glass, I; Vaughn, C

1989-01-01

232

Dilute Group III-V nitride intermediate band solar cells with contact blocking layers  

DOEpatents

An intermediate band solar cell (IBSC) is provided including a p-n junction based on dilute III-V nitride materials and a pair of contact blocking layers positioned on opposite surfaces of the p-n junction for electrically isolating the intermediate band of the p-n junction by blocking the charge transport in the intermediate band without affecting the electron and hole collection efficiency of the p-n junction, thereby increasing open circuit voltage (V.sub.OC) of the IBSC and increasing the photocurrent by utilizing the intermediate band to absorb photons with energy below the band gap of the absorber layers of the IBSC. Hence, the overall power conversion efficiency of a IBSC will be much higher than an conventional single junction solar cell. The p-n junction absorber layers of the IBSC may further have compositionally graded nitrogen concentrations to provide an electric field for more efficient charge collection.

Walukiewicz, Wladyslaw (Kensington, CA); Yu, Kin Man (Lafayette, CA)

2012-07-31

233

Discovery of probable Tunguska cosmic body material: anomalies of platinum group elements and rare-earth elements in peat near the Explosion Site /(1908)  

NASA Astrophysics Data System (ADS)

Ten Sphagnum fuscum peat samples collected from different depths of a core including the layer affected by the 1908 Tunguska explosion in the Tunguska area of Central Siberia, Russia, were analyzed by ICP-MS to determine the concentrations of Pd, Rh, Ru, Co, REE, Y, Sr, and Sc. The analytical results indicate that the Pd and Rh concentrations in the event- and lower layers were 14.0-19.9, and 1.23-1.56 ppb, respectively, about 3-9 times and 3 times higher than the background values in the normal layers. In addition, the patterns of CI-chondrite-normalized REE in the event layers were much flatter than in the normal layers, and differed from those in the nearby traps. Hence, it can be inferred from the characteristics of the elemental geochemistry that the explosion was probably associated with extraterrestrial material, and which, most probably, was a small comet core the dust fraction of which was chemically similar to carbonaceous chondrites (CI). In terms of the Pd and REE excess fluxes in the explosion area, it can be estimated that the celestial body that exploded over Tunguska in 1908 weighed more than 10 6 t, corresponding to a radius of >60 m. If the celestial body was a comet, then its total mass was more than 2×10 7 t, and it had >160 m radius, and released an energy of >10 7 t TNT.

Hou, Q. L.; Kolesnikov, E. M.; Xie, L. W.; Zhou, M. F.; Sun, M.; Kolesnikova, N. V.

2000-12-01

234

Abnormal blood-group-Ss-active sialoglycoproteins in the membrane of Miltenberger class III, IV and V human erythrocytes.  

PubMed

1. We have studied the inherited changes occurring in the sialoglycoproteins of membranes from erythrocytes of type Miltenberger Class III (Mi.III), Miltenberger Class IV (Mi.IV) and Miltenberger Class V (Mi.V) by using sodium dodecyl sulphate/polyacrylamide gel electrophoresis and lactoperoxidase radioiodination. 2. Mi.III erythrocytes lack the normal blood-group-Ss-active sialoglycoprotein but contain an unusual s-active sialoglycoprotein of higher apparent molecular weight. A similar abnormal S-active sialoglycoprotein appears to occur in Mi.IV erythrocytes. 3. The Mi.V condition is associated with the hemizygous absence of both the normal blood-group-MN-active sialoglycoprotein and the normal Ss-active sialoglycorprotein. However, a new sialoglycoprotein component is present in these cells that has properties characteristic of both the MN-active and Ss-active sialoglycoproteins. 4. Our results suggest that the new sialoglycorportein present in Mi.V erythrocytes is a hybrid of the normal MN sialoglycoprotein and an s-active sialoglycoprotein that has properties similar to the s-active sialoglycoprotein found in Mi.III erythrocytes. We suggest that the unusual Mi.V sialoglycoprotein is derived from chromosomal misalignment with unequal crossing-over between the genes for the MN- and Ss-active sialoglycoproteins in a manner similar to that which gives rise to haemoglobin Lepore. 5. Further studies of S-s-erythrocytes confirm that these cells lack normal Ss-active sialoglycoprotein, but contain an unusual component that shows some of the properties of the normal Ss-active sialoglycoprotein. 6. Analysis of erythrocytes of type Mk/Mi.III confirms that, in addition to the known hemizygous lack of the MN-active sialoglycoprotein, the Mk condition is also associated with a loss of the Ss-active sialoglycoprotein. 7. In order to facilitate discussion of the complex changes that occur in these variant erythrocytes, a new unified nomenclature is used for the erythrocyte sialoglycoproteins. PMID:230820

Anstee, D J; Mawby, W J; Tanner, M J

1979-11-01

235

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

PubMed

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

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

2007-12-15

236

The role of group 14 element hydrides in the activation of C-H bonds in cyclic olefins.  

PubMed

Formally, triple-bonded dimetallynes ArEEAr [E = Ge (1), Sn (2); Ar = C(6)H(3)-2,6-(C(6)H(3)-2,6-(i)Pr(2))(2)] have been previously shown to activate aliphatic, allylic C-H bonds in cyclic olefins, cyclopentadiene (CpH), cyclopentene (c-C(5)H(8)) and 1,4-cyclohexadiene, with intriguing selectivity. In the case of the five-membered carbocycles, cyclopentadienyl species ArECp [E = Ge (3), Sn (4)] are formed. In this study, we examine the mechanisms for activation of CpH and c-C(5)H(8) using experimental methods and describe a new product found from the reaction between 1 and c-C(5)H(8), an asymmetrically substituted digermene ArGe(H)Ge(c-C(5)H(9))Ar (5), crystallized in 46% yield. This compound contains a hydrogenated cyclopentyl moiety and is found to be produced in a 3:2 ratio with 3, explaining the fate of the liberated H atoms following triple C-H activation. We show that when these C-H activation reactions are carried out in the presence of tert-butyl ethylene (excess), compounds {ArE(CH(2)CH(2)tBu)}(2) [E = Ge(8), Sn(9)] are obtained in addition to ArECp; in the case of CpH, the neohexyl complexes replace the production of H(2) gas, and for c-C(5)H(8) they displace cyclopentyl product 5 and account for all the hydrogen removed in the dehydroaromatization reactions. To confirm the source of 8 and 9, it was demonstrated that these molecules are formed cleanly between the reaction of (ArEH)(2) [E = Ge(6), Sn(7)] and tert-butyl ethylene, new examples of noncatalyzed hydro-germylation and -stannylation. Therefore, the presence of transient hydrides of the type 6 and 7 can be surmised to be reactive intermediates in the production of 3 and 4, along with H(2), from 1 and 2 and CpH (respectively), or the formation of 3 and 5 from 1. The reaction of 6 or 7 with CpH gave 3 or 4, respectively, with concomitant H(2) evolution, demonstrating the basic nature of these low-valent group 14 element hydrides and their key role in the 'cascade' of C-H activation steps. Additionally, during the course of these studies a new polycyclic compound (ArGe)(2)(C(7)H(12)) (10) was obtained in 60% yield from the reaction of 1,6-heptadiene and 1 via double [2 + 2] cycloaddition and gives evidence for a nonradical mechanism for these types of reactions. PMID:22916997

Summerscales, Owen T; Caputo, Christine A; Knapp, Caroline E; Fettinger, James C; Power, Philip P

2012-09-01

237

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

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.

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

2014-01-01

238

Genetic diversity of European phytoplasmas of the 16SrV taxonomic group and proposal of 'Candidatus Phytoplasma rubi'.  

PubMed

In addition to the grapevine flavescence dorée phytoplasmas, other members of taxonomic group 16SrV phytoplasmas infect grapevines, alders and species of the genera Clematis and Rubus in Europe. In order to investigate which phytoplasmas constitute discrete, species-level taxa, several strains were analysed by comparing their 16S rRNA gene sequences and a set of five housekeeping genes. Whereas 16S rRNA gene sequence similarity values were >97.5?%, the proposed threshold to distinguish two 'Candidatus Phytoplasma' taxa, phylogenetic analysis of the combined sequences of the tuf, rplV-rpsC, rplF-rplR, map and uvrB-degV genetic loci showed that two discrete phylogenetic clusters could be clearly distinguished. The first cluster grouped flavescence dorée (FD) phytoplasmas, alder yellows (AldY) phytoplasmas, Clematis (CL) phytoplasmas and the Palatinate grapevine yellows (PGY) phytoplasmas. The second cluster comprised Rubus stunt (RS) phytoplasmas. In addition to the specificity of the insect vector, the Rubus stunt phytoplasma contained specific sequences in the 16S rRNA gene. Hence, the Rubus stunt phytoplasma 16S rRNA gene was sufficiently differentiated to represent a novel putative taxon: 'Candidatus Phytoplasma rubi'. PMID:20889771

Malembic-Maher, Sylvie; Salar, Pascal; Filippin, Luisa; Carle, Patricia; Angelini, Elisa; Foissac, Xavier

2011-09-01

239

The characteristics of automobile catalyst-derived platinum group elements in road dusts and roadside soils: a case study in the Pearl River Delta region, South China  

Microsoft Academic Search

The emission of platinum group elements (PGE) from automobile catalytic converters has led to enrichment of PGE in road dusts\\u000a and roadside soils in urban areas that are well above the natural background levels. This paper evaluates the source of contamination\\u000a of all the PGE and Au in road dusts and roadside soils in the Pearl River Delta region, including

Liang QiMei-Fu; Mei-Fu Zhou; Zheng Zhao; Jing Hu; Yan Huang

240

Rhenium^Osmium Isotope and Platinum-Group Element Constraints on the Origin and Evolution of the 1? 27 Ga Muskox Layered Intrusion  

Microsoft Academic Search

Platinum-group element (PGE: Os, Ir, Ru, Pt, Pd) and Re^Os isotope systematics determined for the entire preserved stratigraphy of the 1? 27 Ga Muskox intrusion provide an exceptional view of magma chamber processes and mineralization in the main plutonic system of the Mackenzie large igneous province (LIP). We present new Re^Os isotope data for the intrusion, together with PGE and

JAMES M. D. DAY; D. GRAHAM PEARSON; LARRY J. HULBERT

2008-01-01

241

Lie Group of Transformations for a KdV Boussinesq Equation  

NASA Astrophysics Data System (ADS)

We consider a combined Korteweg-deVries and Boussinesq equation governing long surface waves in shallow water. Considering traveling wave solutions, the basic equations will be reduced to a second order ordinary differential equation. Using the Lie group of transformations we reduce it to a first order ordinary differential equation and employ a direct method to derive its periodic solutions in terms of Jacobian elliptic functions and their corresponding solitary wave and explode decay mode solutions.

Krishnan, E. V.; Khan, Q. J. A.

2003-02-01

242

“Structural Transformations in Ceramics: Perovskite-like Oxides and Group III, IV, and V Nitrides”  

SciTech Connect

1 Overview of Results and their Significance Ceramic perovskite-like oxides with the general formula (A. A0. ...)(B. B0. ...)O3and titanium-based oxides are of great technological interest because of their large piezoelectric and dielectric response characteristics.[1] In doped and nanoengineered forms, titantium dioxide finds increasing application as an organic and hydrolytic photocatalyst. The binary main-group-metal nitride compounds have undergone recent advancements of in-situ heating technology in diamond anvil cells leading to a burst of experimental and theoretical interest. In our DOE proposal, we discussed our unique theoretical approach which applies ab initio electronic calculations in conjunction with systematic group-theoretical analysis of lattice distortions to study two representative phase transitions in ceramic materials: (1) displacive phase transitions in primarily titanium-based perovskite-like oxide ceramics, and (2) reconstructive phase transitions in main-group nitride ceramics. A sub area which we have explored in depth is doped titanium dioxide electrical/optical properties.

James P. Lewis (PI, former Co-PI), Dorian M. Hatch (Co-PI, former PI), and Harold T. Stokes (Co-PI)

2006-12-31

243

New clues on outburst mechanisms and improved spectroscopic elements of the black hole binary V4641 Sagittarii*  

NASA Astrophysics Data System (ADS)

We present spectroscopic observations of the black hole binary V4641 Sagittarii, obtained between 2004 July 4 and 2005 March 28, which cover the minor outburst of the star in early 2004 July and quiescence variations on 19 nights scattered over six months. During the outburst, the star peaked approximately 3 mag brighter than usual, and our spectra were dominated by broad hydrogen, helium and iron emission lines. The very first spectra showed P Cygni profiles, which disappeared within a few hours, indicating rapid changes in matter ejection. The H? line had multiple components, one being a broad blueshifted wing exceeding 5000 km s-1. During a simultaneously observed 10-min photometric flare up, the equivalent width of the H? line temporarily decreased, implying that it was a flare of the continuum. The overall spectral appearance was similar to that observed in the 1999 September active phase, which suggests that similar mass-ejection processes were associated with both eruptions. In quiescence, the spectra were those of the early-type secondary star showing its orbital motion around the primary. By measuring cross-correlation radial velocities, we give an improved set of spectroscopic elements. Whereas we measure the same velocity amplitude (K2= 211.3 +/- 1.0 km s-1), within errors, as Orosz et al., our centre-of-mass velocity (?= 72.7 +/- 3.3 km s-1) differs significantly from the previously published value (107.4 +/- 2.9 km s-1). However, we find evidence that the difference is caused by a systematic error in data reduction in the previous study, rather than by gravitational effects of an invisible third component.

Lindstrøm, C.; Griffin, J.; Kiss, L. L.; Uemura, M.; Derekas, A.; Mészáros, Sz.; Székely, P.

2005-11-01

244

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

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

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

245

Porous Silica Sol-Gel Glasses Containing Reactive V2O5 Groups  

NASA Technical Reports Server (NTRS)

Porous silica sol-gel glasses into which reactive vanadium oxide functional groups incorporated exhibit number of unique characteristics. Because they bind molecules of some species both reversibly and selectively, useful as chemical sensors or indicators or as scrubbers to remove toxic or hazardous contaminants. Materials also oxidize methane gas photochemically: suggests they're useful as catalysts for conversion of methane to alcohol and for oxidation of hydrocarbons in general. By incorporating various amounts of other metals into silica sol-gel glasses, possible to synthesize new materials with broad range of new characteristics.

Stiegman, Albert E.

1995-01-01

246

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

SciTech Connect

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

Despotopulos, J D; Sudowe, R

2012-02-21

247

A complex array of DNA-binding proteins required for pairing-sensitive silencing by a polycomb group response element from the Drosophila engrailed gene.  

PubMed Central

Regulatory DNA from the Drosophila gene engrailed causes silencing of a linked reporter gene (mini-white) in transgenic Drosophila. This silencing is strengthened in flies homozygous for the transgene and has been called "pairing-sensitive silencing." The pairing-sensitive silencing activities of a large fragment (2.6 kb) and a small subfragment (181 bp) were explored. Since pairing-sensitive silencing is often associated with Polycomb group response elements (PREs), we tested the activities of each of these engrailed fragments in a construct designed to detect PRE activity in embryos. Both fragments were found to behave as PREs in a bxd-Ubx-lacZ reporter construct, while the larger fragment showed additional silencing capabilities. Using the mini-white reporter gene, a 139-bp minimal pairing-sensitive element (PSE) was defined. DNA mobility-shift assays using Drosophila nuclear extracts suggested that there are eight protein-binding sites within this 139-bp element. Mutational analysis showed that at least five of these sites are important for pairing-sensitive silencing. One of the required sites is for the Polycomb group protein Pleiohomeotic and another is GAGAG, a sequence bound by the proteins GAGA factor and Pipsqueak. The identity of the other proteins is unknown. These data suggest a surprising degree of complexity in the DNA-binding proteins required for PSE function. PMID:11973310

Americo, Jeffrey; Whiteley, Mary; Brown, J Lesley; Fujioka, Miki; Jaynes, James B; Kassis, Judith A

2002-01-01

248

Abnormal blood-group-Ss-active sialoglycoproteins in the membrane of Miltenberger class III, IV and V human erythrocytes.  

PubMed Central

1. We have studied the inherited changes occurring in the sialoglycoproteins of membranes from erythrocytes of type Miltenberger Class III (Mi.III), Miltenberger Class IV (Mi.IV) and Miltenberger Class V (Mi.V) by using sodium dodecyl sulphate/polyacrylamide gel electrophoresis and lactoperoxidase radioiodination. 2. Mi.III erythrocytes lack the normal blood-group-Ss-active sialoglycoprotein but contain an unusual s-active sialoglycoprotein of higher apparent molecular weight. A similar abnormal S-active sialoglycoprotein appears to occur in Mi.IV erythrocytes. 3. The Mi.V condition is associated with the hemizygous absence of both the normal blood-group-MN-active sialoglycoprotein and the normal Ss-active sialoglycorprotein. However, a new sialoglycoprotein component is present in these cells that has properties characteristic of both the MN-active and Ss-active sialoglycoproteins. 4. Our results suggest that the new sialoglycorportein present in Mi.V erythrocytes is a hybrid of the normal MN sialoglycoprotein and an s-active sialoglycoprotein that has properties similar to the s-active sialoglycoprotein found in Mi.III erythrocytes. We suggest that the unusual Mi.V sialoglycoprotein is derived from chromosomal misalignment with unequal crossing-over between the genes for the MN- and Ss-active sialoglycoproteins in a manner similar to that which gives rise to haemoglobin Lepore. 5. Further studies of S-s-erythrocytes confirm that these cells lack normal Ss-active sialoglycoprotein, but contain an unusual component that shows some of the properties of the normal Ss-active sialoglycoprotein. 6. Analysis of erythrocytes of type Mk/Mi.III confirms that, in addition to the known hemizygous lack of the MN-active sialoglycoprotein, the Mk condition is also associated with a loss of the Ss-active sialoglycoprotein. 7. In order to facilitate discussion of the complex changes that occur in these variant erythrocytes, a new unified nomenclature is used for the erythrocyte sialoglycoproteins. Images Fig. 1. Fig. 2. Fig. 4. Fig. 5. Fig. 7. Fig. 9. PMID:230820

Anstee, D J; Mawby, W J; Tanner, M J

1979-01-01

249

Effects of rare earth elements substitution for Ti on the structure and electrochemical properties of a Fe-doped Ti–V-based hydrogen storage alloy  

Microsoft Academic Search

Effects of a partial substitution of rare-earth elements of Y, La, Ce, Pr, Nd in an atom fraction of 1\\/8 for Ti on the structure and electrochemical property of a Fe-doped Ti–V-based hydrogen storage alloy, Ti0.8Zr0.2V2.7Mn0.5Cr0.6Ni1.25Fe0.2, have been investigated systematically using X-ray diffraction, scanning electron microscope, energy dispersive spectroscope and electrochemical tests including charge\\/discharge, high rate dischargeability, polarization, etc. The

Mingxia Gao; He Miao; Yu Zhao; Yongfeng Liu; Hongge Pan

2009-01-01

250

Results of the Survey of RP Group Members: An Element in Strategic Planning for the Research & Planning Unit.  

ERIC Educational Resources Information Center

This document focuses on a stakeholder survey for a research unit. Although it covers just one part of the overall planning process that the Research & Planning (RP) Unit at the California Community Colleges Chancellor's Office, the researchers did survey other groups in the strategic planning effort. The stakeholder survey focused on four general…

Hom, Willard

251

Incoherent scattering of 59.54 keV gamma rays by selected elements in the atomic region 29<=Z<=74  

Microsoft Academic Search

Incoherent scattering cross-sections for 11 moderate to high atomic number elements have been experimentally determined using 59.54 keV gamma rays emitted by the radionuclide 241Am. Measurements were performed using a standard back-scattering geometry set up to obtain scattering angles of 145 deg, 154 deg and 165 deg. Resulting photon momentum transfers were in the range 4.58<=x<=4.76 Å-1. High purity (better

I. S. Elyaseery; A. Shukri; C. S. Chong; A. A. Tajuddin; D. A. Bradley

1999-01-01

252

Exploring the potential energy surface of E?P? clusters (E=Group 13 element): the quest for inverse carbon-free sandwiches.  

PubMed

Inverse carbon-free sandwich structures with formula E2P4 (E=Al, Ga, In, Tl) have been proposed as a promising new target in main-group chemistry. Our computational exploration of their corresponding potential-energy surfaces at the S12h/TZ2P level shows that indeed stable carbon-free inverse-sandwiches can be obtained if one chooses an appropriate Group?13 element for E. The boron analogue B2P4 does not form the D(4h)-symmetric inverse-sandwich structure, but instead prefers a D(2d) structure of two perpendicular BP2 units with the formation of a double B-B bond. For the other elements of Group?13, Al-Tl, the most favorable isomer is the D(4h) inverse-sandwich structure. The preference for the D(2d) isomer for B2P4 and D(4h) for their heavier analogues has been rationalized in terms of an isomerization-energy decomposition analysis, and further corroborated by determination of aromaticity of these species. PMID:24700524

Castro, Abril C; Osorio, Edison; Cabellos, José Luis; Cerpa, Erick; Matito, Eduard; Solà, Miquel; Swart, Marcel; Merino, Gabriel

2014-04-14

253

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

SciTech Connect

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}.

Freeman, John C.; /LBL, Berkeley

2007-12-01

254

A Measurement of the Top Quark Mass in 1.96 TeV Proton-Antiproton Collisions Using a Novel Matrix Element Method  

SciTech Connect

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 element techniques, the method involves an integration using the Standard Model matrix element for t{bar t} 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}.

CDF Collaboration; Freeman, John; Freeman, John

2007-09-30

255

75 FR 45623 - Morris Energy Group, LLC v.PSEG Energy Resources & Trade LLC; PSEG Fossil LLC; and PSEG Power LLC...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Energy Group, LLC v.PSEG Energy Resources & Trade LLC; PSEG Fossil LLC; and PSEG Power LLC; Notice of Complaint July 27, 2010...complaint against PSEG Energy Resources & Trade, LLC, PSEG Fossil LLC and PSEG Power LLC (PSEG Power Companies)...

2010-08-03

256

New Physics at the LHC. A Les Houches Report: Physics at TeV Colliders 2009 - New Physics Working Group  

E-print Network

We present a collection of signatures for physics beyond the standard model that need to be explored at the LHC. First, are presented various tools developed to measure new particle masses in scenarios where all decays include an unobservable particle. Second, various aspects of supersymmetric models are discussed. Third, some signatures of models of strong electroweak symmetry are discussed. In the fourth part, a special attention is devoted to high mass resonances, as the ones appearing in models with warped extra dimensions. Finally, prospects for models with a hidden sector/valley are presented. Our report, which includes brief experimental and theoretical reviews as well as original results, summarizes the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 8-26 June, 2009).

G. Brooijmans; C. Grojean; G. D. Kribs; C. Shepherd-Themistocleous; K. Agashe; L. Basso; G. Belanger; A. Belyaev; K. Black; T. Bose; R. Brunelière; G. Cacciapaglia; E. Carrera; S. P. Das; A. Deandrea; S. De Curtis; A. -I. Etienvre; J. R. Espinosa; S. Fichet; L. Gauthier; S. Gopalakrishna; H. Gray; B. Gripaios; M. Guchait; S. J. Harper; C. Henderson; J. Jackson; M. Karagöz; S. Kraml; K. Lane; T. Lari; S. J. Lee; J. R. Lessard; Y. Maravin; A. Martin; B. McElrath; G. Moreau; S. Moretti; D. E. Morrissey; M. Mühlleitner; D. Poland; G. M. Pruna; A. Pukhov; A. R. Raklev; T. Robens; R. Rosenfeld; H. Rzehak; G. P. Salam; S. Sekmen; G. Servant; R. K. Singh; B. C. Smith; M Spira; M. J. Strassler; I. Tomalin; M. Tytgat; M. Vos; J. G. Wacker; P. v. Weitershausen; K. M. Zurek

2010-05-07

257

Spin Density Matrix Elements in Exclusive rho^0 Electroproduction on 1H and 2H Targets at 27.5 GeV Beam Energy  

E-print Network

Spin Density Matrix Elements (SDMEs) describing the angular distribution of exclusive rho^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 GeV^2 < Q^2 < 7 GeV^2, 3.0 GeV < W < 6.3 GeV, and -t < 0.4 GeV^2. 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 rho^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.

HERMES Collaboration; A. Airapetian

2009-06-13

258

Transcriptional and Proteomic Profiles of Group B Streptococcus Type V Reveal Potential Adherence Proteins Associated with High-Level Invasion?  

PubMed Central

Group B Streptococcus (GBS) is an opportunistic organism that can harmlessly colonize the human gut, vagina, and rectum but can also cause pneumonia, sepsis, and meningitis in neonates born to colonized mothers. We have shown previously that growth rate and oxygen level regulate the ability of GBS to invade eukaryotic cells in vitro. Herein we extend and expand on these observations to show that GBS type V, an emergent serotype, grown in a chemostat at a cell mass-doubling time (td) of 1.8 h with oxygen invaded human ME-180 cervical epithelial cells in large numbers compared with those grown at the same td without oxygen or at a slower td of 11.0 h. The fact that several GBS type V cell wall-associated and membrane proteins were expressed exclusively under the invasive growth condition prompted an investigation, using genomics and proteomics, of all upregulated genes and proteins. Several proteins with potential roles in adherence were identified, including an undefined surface antigen (SAG1350), a lipoprotein (SAG0971), penicillin-binding protein 2b (SAG0765), glyceraldehyde-3-phosphate dehydrogenase (SAG0823), and an iron-binding protein (SAG1007). Mouse antisera to these five proteins inhibited binding of GBS type V to ME-180 cells by ?85%. Recombinant undefined surface antigen (SAG1350), lipoprotein (SAG0971), and penicillin-binding protein 2b (SAG0765) each bound to ME-180 cells in a dose-dependent fashion, confirming their ability to act as ligands. Collectively, these data increase the number of potential GBS adherence factors and also suggest a role for these surface-associated proteins in initial pathogenic events. PMID:17210664

Johri, Atul K.; Margarit, Immaculada; Broenstrup, Mark; Brettoni, Cecilia; Hua, Lei; Gygi, Steven P.; Telford, John L.; Grandi, Guido; Paoletti, Lawrence C.

2007-01-01

259

Search for a meteoritic component in drill cores from the Bosumtwi impact structure, Ghana: Platinum group element contents and osmium isotopic characteristics  

NASA Astrophysics Data System (ADS)

An attempt was made to detect a meteoritic component in both crater-fill (fallback) impact breccias and fallout suevites (outside the crater rim) at the Bosumtwi impact structure in Ghana. Thus far, the only clear indication for an extraterrestrial component related to this structure has been the discovery of a meteoritic signature in Ivory Coast tektites, which formed during the Bosumtwi impact event. Earlier work at Bosumtwi indicated unusually high levels of elements that are commonly used for the identification of meteoritic contamination (i.e., siderophile elements, including the platinum group elements [PGE]) in both target rocks and impact breccias from surface exposures around the crater structure, which does not allow unambiguous verification of an extraterrestrial signature. The present work, involving PGE abundance determinations and Os isotope measurements on drill core samples from inside and outside the crater rim, arrives at the same conclusion. Despite the potential of the Os isotope system to detect even small amounts of extraterrestrial contribution, the wide range in PGE concentrations and Os isotope composition observed in the target rocks makes the interpretation of unradiogenic, high-concentration samples as an impact signature ambiguous.

McDonald, Iain; Peucker-Ehrenbrink, Bernhard; Coney, Louise; Ferrière, Ludovic; Reimold, Wolf Uwe; Koeberl, Christian

260

G2(+)M study on N-alkylamino cation affinities of neutral main-group element hydrides: trends across the periodic table.  

PubMed

We have made an extensive theoretical exploration of gas-phase N-alkylamino cation affinities (NAAMCA), including amino cation affinities (AMCA) and N-dimethylamino cation affinities (NDMAMCA), of neutral main-group element hydrides of groups 15-17 and periods 2-4 in the periodic table by using the G2(+)M method. Some similarities and differences are found between NAAMCA and the corresponding alkyl cation affinities (ACA) of H(n)X. Our calculations show that the AMCA and NDMAMCA are systematically lower than the corresponding proton affinities (PA) for H(n)X. In general, there is no linear correlation between NAAMCA and PA of H(n)X. Instead, the correlations exist only within the central elements X in period 2, or periods 3-4, which is significantly different from the reasonable correlations between ACA and PA for all H(n)X. NAAMCA (H(n)X) are weaker than NAAMCA (H(n-1)X(-)) by more than 700 kJ/mol and generally stronger than ACA (H(n)X), with three exceptions: H2ONR2(+)(R = H, Me) and HFNH2(+). These new findings can be rationalized by the negative hyperconjugation and Pauli repulsion. PMID:24738576

Geng, Song; Wu, Ding-Lu; Yang, Jing; Wei, Xi-Guang; Zhu, Jun; Zhang, Hai-Bo; Ren, Yi; Lau, Kai-Chung

2014-05-01

261

Platinum Group Element (PGE) Abundances in Lava Flows Generated by the Hawaiian Plume: Insights into Plume Evolution  

NASA Astrophysics Data System (ADS)

Picritic and high-MgO (7.7-24 wt.%) basalt samples from Detroit (/sim81-76 Ma) and Koko (/sim48 Ma) Seamounts along the ESC have been analyzed for PGEs (Ru, Rh, Pd, Ir, and Pt) allowing an examination of how the PGEs in lavas from the Hawaiian plume have changed over time. Major and trace element (including the PGEs) concentrations were quantified by ICP methods at the University of Notre Dame. See Ely et al. (1999, Chem. Geol. 157:219) for the PGE analytical method. Bennett et al. (2000) analyzed Hawaiian picrites and found PGE abundances slightly greater than average MORB and comparable to the low-PGE basaltic komatiites. These authors modeled the PGE abundances of these picrites by using variable amounts of residual sulfide during melting, such that Koolau (low PGE contents) formed from a relatively sulfide-rich source and Loihi (high PGEs) from a sulfide-poor source. Our PGE data from Detroit Seamount show slightly higher PGE abundances than Loihi and Kilauea, suggesting these picrites formed from a source lacking residual sulfide. These results suggest that, if the model of Bennett et al. (2000) is correct, the dilution of plume lava with MORB source, as hypothesized on the basis of depleted isotope ratios and lower trace element abundances than modern Hawaii (Keller et al., 2000, Nature 405:603; Kinman & Neal, 2002, Eos 83:F1282; Regelous et al., 2003, JPet 44:113), was not the controlling factor in PGE abundances. However, since MORB PGE concentrations are not substantially different than low-PGE Hawaiian picrites, incorporation of MORB material within the Hawaiian plume at Detroit Seamount would not have drastically reduced the PGE abundances. Koko Seamount has relatively high PGE concentrations (/sim3-12 times greater than those from Detroit lavas). This may be the result of a lack of residual sulfide facilitated by higher degrees of partial melting. Although our initial data are consistent with variable degrees of partial melting and/or source heterogeneity over the life of the Hawaiian plume, the data from Detroit Seamount can be modeled by, for example, magma mixing between Koko-type "PGE-rich" plume and MORB end members (cf. Kinman & Neal, 2002). The Pt/Ir ratios and PGE abundances of picrites from Detroit and Koko Seamounts and from Hawaii (as analyzed by Bennett et al., 2000) increase in the order: Hawaii (4.8), Detroit (5.8), Koko (8.1). Bennett et al. argued that if more sulfide was retained in the source the PGE profile would be more fractionated and abundances would be lower. Our data suggest the opposite is true. For Koko Seamount to have PGE abundances approximately 3-12 times greater than the high-PGE picrites from Hawaii and yet have a more fractionated profile, the source of the Hawaiian plume must have been relatively PGE-enriched at 48 Ma than it is currently. In addition, the more fractionated profile of Detroit Seamount is consistent with the incorporation of MORB material (Pt/Ir /sim 25.9), thereby raising its Pt/Ir ratio.

Shafer, J. T.; Neal, C. R.

2003-12-01

262

The content of selected chemical elements in the hair of young men of the Bantu language group from Tanzania versus environmental and social conditioning.  

PubMed

Research works that would determine the content of chemical elements in black population organisms on the basis of hair analysis are not numerous. There are no studies referring to black populations living in indigenous environment, like the Mafinga region, Iringa District in Tanzania examined by us. The aim of the study performed was to analyse the content of chemical elements Fe, Ca, Mg, Zn and Cu in easily available biological media like hair. The material was collected in October 2005 and March 2006 during anthropological examination, which came from young males (n?=?91), students of a secondary school. Large Ca concentration range was found for the total number of subjects (680.20 to 2,089.70?µg/g d.m.). Mean Fe content in hair for the total number of subjects was 11.19?±?3.70?µg/g d.m., while that of Mg 6.84?±?2.02?µg/g d.m. Mean Zn concentration for the total number of subjects was 91.06?±?39.22?µg/g d.m., being significantly higher in younger group than in older one (p?=?0.039). Mean Cu concentration in hair for the total number of subjects was 7.50?±?2.90?µg/g d.m Body mass index (BMI?=?kg/m²) was calculated for the subjects showing that out of 91 men participating in the study 15.4% was characterised by mediocre nutrition. No statistically significant correlations were found between BMI and the analysed chemical elements. The analysis of the content of trace elements in the hair of the examined young males showed deficiencies in Zn, Cu, Fe and significantly in Mg. PMID:20041314

R?bacz, Ewa; Baranowska-Bosiacka, Irena; Chlubek, Dariusz

2010-12-01

263

Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, clark county, Nevada  

USGS Publications Warehouse

The Goodsprings district, Clark County, Nevada, includes zinc-dominant carbonate replacement deposits of probable late Paleozoic age, and lead-dominant carbonate replacement deposits, copper ?? precious metal-platinum group element (PGE) deposits, and gold ?? silver deposits that are spatially associated with Late Triassic porphyritic intrusions. The district encompasses ??500 km2 although the distribution of all deposits has been laterally condensed by late Mesozoic crustal contraction. Zinc, Pb, and Cu production from about 90 deposits was ??160,000 metric tons (t) (Zn > Pb >> Cu), 2.1 million ounces (Moz) Ag, 0.09 Moz Au, and small amounts of PGEs-Co, V, Hg, Sb, Ni, Mo, Mn, Ir, and U-were also recovered. Zinc-dominant carbonate replacement deposits (Zn > Pb; Ag ?? Cu) resemble Mississippi Valley Type (MVT) Zn-Pb deposits in that they occur in karst and fault breccias in Mississippian limestone where the southern margin of the regional late Paleozoic foreland basin adjoins Proterozoic crystalline rocks of the craton. They consist of calcite, dolomite, sphalerite, and galena with variably positive S isotope compositions (??34S values range from 2.5-13%), and highly radiogenic Pb isotope compositions (206Pb/204Pb >19), typical of MVT deposits above crystalline Precambrian basement. These deposits may have formed when southward flow of saline fluids, derived from basinal and older sedimentary rocks, encountered thinner strata and pinch-outs against the craton, forcing fluid mixing and mineral precipitation in karst and fault breccias. Lead-dominant carbonate replacement deposits (Pb > Zn, Ag ?? Cu ?? Au) occur among other deposit types, often near porphyritic intrusions. They generally contain higher concentrations of precious metals than zinc-dominant deposits and relatively abundant iron oxides after pyrite. They share characteristics with copper ?? precious metal- PGE and gold ?? silver deposits including fine-grained quartz replacement of carbonate minerals in ore breccias and relatively low S and Pb isotope values (??34S values vary from 0-??4%; 206Pb/204Pb <18.5). Copper ?? precious metal-PGE deposits (Cu, Co, Ag, Au, Pd, and Pt) consist of Cu carbonate minerals (after chalcocite and chalcopyrite) and fine-grained quartz that have replaced breccia clasts and margins of fissures in Paleozoic limestones and dolomites near porphyritic intrusions. Gold ?? silver deposits occur along contacts and within small-volume stocks and dikes of feldspar porphyry, one textural variety of porphyritic intrusions. Lead isotope compositions of copper ?? precious metal-PGE, gold ?? silver, and lead-dominant carbonate replacement deposits are similar to those of Mojave crust plutons, indicating derivation of Pb from 1.7 Ga crystalline basement or from Late Proterozoic siliciclastic sedimentary rocks derived from 1.7 Ga crystalline basement. Four texturally and modally distinctive porphyritic intrusions are exposed largely in the central part of the district: feldspar quartz porphyry, plagioclase quartz porphyry, feldspar biotite quartz porphyry, and feldspar porphyry. Intrusions consist of 64 to 70 percent SiO2 and variable K2O/Na2O (0.14-5.33) that reflect proportions of K-feldspar and albite phenocrysts and megacrysts as well as partial alteration to K-mica; quartz and biotite phenocrysts are present in several subtypes. Albite may have formed during emplacement of magma in brine-saturated basinal strata, whereas hydrothermal alteration of matrix, phenocrystic, and megacrystic feldspar and biotite to K-mica, pyrite, and other hydrothermal minerals occurred during and after intrusion emplacement. Small volumes of garnet-diopside-quartz and retrograde epidote-mica-amphibole skarn have replaced carbonate rocks adjacent to one intrusion subtype (feldspar-quartz porphyry), but alteration of carbonate rocks at intrusion contacts elsewhere is inconsp. Uranium-lead ages of igneous zircons vary inconsistently from ?? 180 to 230

Vikre, P.; Browne, Q.J.; Fleck, R.; Hofstra, A.; Wooden, J.

2011-01-01

264

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

PubMed Central

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

2013-01-01

265

III-V arsenide-nitride semiconductor  

NASA Technical Reports Server (NTRS)

III-V arsenide-nitride semiconductor are disclosed. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V materials varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V material can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

2000-01-01

266

Group Therapy within the NHS V: Patients' Views on the Benefit of Group Therapy for Women Survivors of Child Sexual Abuse  

Microsoft Academic Search

This article reports on a study of how members of a slow-open analytic group for women survivors of childhood sexual abuse felt about the helpfulness of the group. The respondents' views and comments are analysed and related to their age, their termination of the group, length of follow-up, number of sessions, final stage of depression and overall change in depression

Zaida Hall; Elizabeth King

1997-01-01

267

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

SciTech Connect

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)

Ross, A.W.; Fink, M.

1986-12-01

268

Along-arc variations in lithospheric mantle compositions in Kamchatka, Russia: First trace element data on mantle xenoliths from the Klyuchevskoy Group volcanoes  

NASA Astrophysics Data System (ADS)

We provide results of a detailed study of the first peridotite xenoliths of proven mantle origin reported from Bezymyanny volcano in the Klyuchevskoy Group, northern Kamchatka arc. The xenoliths are coarse spinel harzburgites made up mainly of Mg-rich olivine as well as subhedral orthopyroxene (opx) and Cr-rich spinel, and also contain fine-grained interstitial pyroxenes, amphibole and feldspar. The samples are unique in preserving the evidence for both initial arc mantle substrate produced by high-degree melt extraction and subsequent enrichment events. We show that the textures, modal and major oxide compositions of the Bezymyanny xenoliths are generally similar to those of spinel harzburgite xenoliths from Avacha volcano in southern Kamchatka. However, coarse opx from the Bezymyanny harzburgites has higher abundances of light and medium rare earth elements and other highly incompatible elements than coarse opx from the Avacha harzburgites. We infer that (1) the sub-arc lithospheric mantle beneath both Avacha and Bezymyanny (and possibly between these volcanoes) consists predominantly of harzburgitic melting residues, which experienced metasomatism by slab-related fluids or low-fraction, fluid-rich melts and (2) the degrees of metasomatism are higher beneath Bezymyanny. By contrast, xenolith suites from Shiveluch and Kharchinsky volcanoes 50-100 km north of the Klyuchevskoy Group include abundant cumulates and products of reaction of mantle rocks with silicate melts at high melt/rock ratios. The high melt flux through the lithospheric mantle beneath Shiveluch and Kharchinsky may be related to the asthenospheric flow around the northern edge of the sinking Pacific plate; lateral propagation of fluids in the mantle wedge south of the plate edge may contribute to metasomatism in the mantle lithosphere beneath the Klyuchevskoy Group volcanoes.

Ionov, D. A.; Bénard, A.; Plechov, P. Yu.; Shcherbakov, V. D.

2013-08-01

269

Platinum-group element, Gold, Silver and Base Metal distribution in compositionally zoned sulfide droplets from the Medvezky Creek Mine, Noril'sk, Russia  

USGS Publications Warehouse

Concentrations of Ag, Au, Cd, Co, Re, Zn and Platinum-group elements (PGE) have been determined in sulfide minerals from zoned sulfide droplets of the Noril'sk 1 Medvezky Creek Mine. The aims of the study were; to establish whether these elements are located in the major sulfide minerals (pentlandite, pyrrhotite, chalcopyrite and cubanite), to establish whether the elements show a preference for a particular sulfide mineral and to investigate the model, which suggests that the zonation in the droplets is caused by the crystal fractionation of monosulfide solid solution (mss). Nickel, Cu, Ag, Re, Os, Ir, Ru, Rh and Pd, were found to be largely located in the major sulfide minerals. In contrast, less than 25% of the Au, Cd, Pt and Zn in the rock was found to be present in these sulfides. Osmium, Ir, Ru, Rh and Re were found to be concentrated in pyrrhotite and pentlandite. Palladium and Co was found to be concentrated in pentlandite. Silver, Cd and Zn concentrations are highest in chalcopyrite and cubanite. Gold and platinum showed no preference for any of the major sulfide minerals. The enrichment of Os, Ir, Ru, Rh and Re in pyrrhotite and pentlandite (exsolution products of mss) and the low levels of these elements in the cubanite and chalcopyrite (exsolution products of intermediate solid solution, iss) support the mss crystal fractionation model, because Os, Ir, Ru, Rh and Re are compatible with mss. The enrichment of Ag, Cd and Zn in chalcopyrite and cubanite also supports the mss fractionation model these minerals are derived from the fractionated liquid and these elements are incompatible with mss and thus should be enriched in the fractionated liquid. Gold and Pt do not partition into either iss or mss and become sufficiently enriched in the final fractionated liquid to crystallize among the iss and mss grains as tellurides, bismithides and alloys. During pentlandite exsolution Pd appears to have diffused from the Cu-rich portion of the droplet into pentlandite. ?? Springer-Verlag 2006.

Barnes, S.-J.; Cox, R.A.; Zientek, M.L.

2006-01-01

270

Spin-density matrix elements for ?p?K*0?+ at E?=1.85-3.0 GeV with evidence for the ?(800) meson exchange.  

PubMed

The exclusive reaction ?p?K(+)?(-)?(+) was measured for the first time using linearly polarized photons at beam energies from 1.85 to 2.96 GeV. Angular distributions in the rest frame of the K(+)?(-) system were fitted to extract spin-density matrix elements of the K(*0) decay. The measured parity spin asymmetry shows that natural-parity exchange is dominant in this reaction. This result clearly indicates the need for t-channel exchange of the ?(800) scalar meson. PMID:22463625

Hwang, S H; Hicks, K; Ahn, J K; Nakano, T; Ahn, D S; Chang, W C; Chen, J Y; Daté, S; Ejiri, H; Fujimura, H; Fujiwara, M; Fukui, S; Gohn, W; Hotta, T; Imai, K; Ishikawa, T; Joo, K; Kato, Y; Kohri, H; Kon, Y; Lee, H S; Maeda, Y; Miyabe, M; Mibe, T; Morino, Y; Muramatsu, N; Nakatsugawa, Y; Niiyama, M; Noumi, H; Oh, Y; Ohashi, Y; Ohta, T; Oka, M; Parker, J; Rangacharyulu, C; Ryu, S Y; Sawada, T; Sugaya, Y; Sumihama, M; Tsunemi, T; Uchida, M; Ungaro, M; Yosoi, M

2012-03-01

271

Total L-shell X-ray production cross sections by 400-700 keV proton impact for elements with 34 < or = Z < or = 53.  

PubMed

Total L-shell X-ray production cross sections induced by protons with energies between 400 and 700 keV were measured for elements with atomic number Z between 34 and 53. The ECPSSR theory describes appropriately the results. This model modifies the plane wave born approximation by considering projectile energy loss (E), Coulomb deflection of the incoming ion (C), polarization and change in electron binding energies through a perturbed stationary states method (PSS) and relativistic values of target electron mass (R). A comparison is given with previously published data for proton energies below 1 MeV and 26 < or = Z < or = 53, based on a scaling obtained from a reduced velocity parameter zeta(L)R. The results show that the scaling for these atomic numbers and energy ranges is adequate and a semi-empirical expression to calculate those cross sections is proposed. PMID:11214881

Miranda, J; Ledesma, R; de Lucio, O G

2001-03-01

272

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

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

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

1998-08-01

273

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

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.

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

274

Experimental design and optimization of leaching process for recovery of valuable chemical elements (U, La, V, Mo, Yb and Th) from low-grade uranium ore.  

PubMed

The paper deals with experimental design and optimization of leaching process of uranium and associated metals from low-grade, Polish ores. The chemical elements of interest for extraction from the ore were U, La, V, Mo, Yb and Th. Sulphuric acid has been used as leaching reagent. Based on the design of experiments the second-order regression models have been constructed to approximate the leaching efficiency of elements. The graphical illustrations using 3-D surface plots have been employed in order to identify the main, quadratic and interaction effects of the factors. The multi-objective optimization method based on desirability approach has been applied in this study. The optimum condition have been determined as P=5 bar, T=120 °C and t=90 min. Under these optimal conditions, the overall extraction performance is 81.43% (for U), 64.24% (for La), 98.38% (for V), 43.69% (for Yb) and 76.89% (for Mo) and 97.00% (for Th). PMID:24857897

Zakrzewska-Koltuniewicz, Gra?yna; Herdzik-Koniecko, Irena; Cojocaru, Corneliu; Chajduk, Ewelina

2014-06-30

275

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

E-print Network

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 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.

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

276

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

SciTech Connect

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.

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

277

Methods for forming group III-arsenide-nitride semiconductor materials  

NASA Technical Reports Server (NTRS)

Methods are disclosed for forming Group III-arsenide-nitride semiconductor materials. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

2002-01-01

278

Formation of a reliable intermediate band in Si heavily coimplanted with chalcogens (S, Se, Te) and group III elements (B, Al)  

NASA Astrophysics Data System (ADS)

This first-principles study describes the properties of Si implanted with several chalcogen species (S, Se, Te) at doses considerably above the equilibrium solubility limit, especially when coimplanted with the group III atoms B and Al. The measurements of chalcogen-implanted Si show strong optical absorption in the infrared range. The calculations carried out show that substitution of Si by chalcogen atoms requires lower formation energy than the interstitial implantation. In the resulting electronic structure, at concentrations close to 0.5%, an impurity band determined by the properties of the chalcogens introduced is observed in the forbidden energy gap of Si. Although this band is a few tenths of an electron volt wide, it remains energetically isolated from both the valence and the conduction bands. Appropriate coimplantation with group III elements allows control over the occupation of the intermediate band while modifying its energies only slightly. A moderate energy gain (especially small for B) seems to be obtained when p -doping atoms occupy the sites next to those of the chalcogens. Therefore, the apparent electrostatic attraction between species that in isolation would act as acceptors and double donors is smaller than expected. The intermediate-band properties have been preserved for all of the coimplanted compounds analyzed here, regardless of the species involved or the distance between them, which constitutes an appreciable advantage for the design of new experimental materials.

Sánchez, K.; Aguilera, I.; Palacios, P.; Wahnón, P.

2010-10-01

279

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)

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.

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

280

Revised Energy Spectra for Primary Elements (H - Si) above 50 GeV from the ATIC-2 Science Flight  

NASA Astrophysics Data System (ADS)

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 data.

Wefel, J. P.; Adams, J. H., Jr.; Ahn, H. S.; et al.

281

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

NASA Technical Reports Server (NTRS)

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.

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

282

Uncertainty Principles for Compact Groups  

E-print Network

We establish an operator-theoretic uncertainty principle over arbitrary compact groups, generalizing several previous results. As a consequence, we show that if f is in L^2(G), then the product of the measures of the supports of f and its Fourier transform ^f is at least 1; here, the dual measure is given by the sum, over all irreducible representations V, of d_V rank(^f(V)). For finite groups, our principle implies the following: if P and R are projection operators on the group algebra C[G] such that P commutes with projection onto each group element, and R commutes with left multiplication, then the squared operator norm of PR is at most rank(P)rank(R)/|G|.

Gorjan Alagic; Alexander Russell

2008-08-29

283

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

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]<0) for [Fe/H]<0. Also, for Mn, when NLTE correct...

Battistini, Chiara

2015-01-01

284

ENVIRONMENTAL TECHNOLOGY VERIFICATION, TEST REPORT OF CONTROL OF BIOAEROSOLS IN HVAC SYSTEMS, FILTRATION GROUP, AEROSTAR FP-98 MINIPLEAT V-BLANK FILTER  

EPA Science Inventory

The Environmental Technology Verification report discusses the technology and performance of the AeroStar FP-98 Minipleat V-Bank Filter air filter for dust and bioaerosol filtration manufactured by Filtration Group. The pressure drop across the filter was 137 Pa clean and 348 Pa ...

285

Effects of mother lode-type gold mineralization on 187Os/188Os and platinum group element concentrations in peridotite: Alleghany District, California  

USGS Publications Warehouse

Osmium isotope compositions and concentrations of Re, platinum group elements (PGE), and Au were determined for host peridotites (serpentinites and barzburgites) and hydrothermally altered ultramafic wall rocks associated with Mother Lode-type hydrothermal gold-quartz vein mineralization in the Alleghany district, California. The host peridotites have Os isotope compositions and Re, PGE, and Au abundances typical of the upper mantle at their presumed formation age during the late Proterozoic or early Paleozoic. The hydrothermally altered rocks have highly variable initial Os isotope compositions with ??os, values (% deviation of 187OS/188OS from the chondritic average calculated for the approx. 120 Ma time of mineralization) ranging from -1.4 to -8.3. The lowest Os isotope compositions are consistent with Re depletion of a chondritic source (e.g., the upper mantle) at ca. 1.6 Ga. Most of the altered samples are enriched in Au and have depleted and fractionated abundances of Re and PGE relative to their precursor peridotites. Geoehemical characteristics of the altered samples suggest that Re and some PGE were variably removed from the ultramafic rocks during the mineralization event. In addition to Re, the Pt and Pd abundances of the most intensely altered rocks appear to have been most affected by mineralization. The 187Os-depleted isotopic compositions of some altered rocks are interpreted to be a result of preferential 187Os loss via destruction of Re-rich phases during the event. For these rocks, Os evidently is not a useful tracer of the mineralizing fluids. The results do, however, provide evidence for differential mobility of these elements, and mobility of 187Os relative to the initial bulk Os isotope composition during hydrothermal metasomatic alteration of ultramafic rocks. ?? 2007 Society of Economic Geologists, Inc.

Walker, R.J.; Böhlke, J.K.; McDonough, W.F.; Li, J.

2007-01-01

286

Structural distortions in M[E(SiMe?)?]? complexes (M = group 15, f-element; E = N, CH): is three a crowd?  

PubMed

The tris(bistrimethylsilylamido) species P[N(SiMe3)2]3 (1) and As[N(SiMe3)2]3 (2) have been prepared through halide metathesis in high yield. Their single crystal X-ray structures, along with that of Sb[N(SiMe3)2]3 (3), complete the series of structurally authenticated group 15 M[N(SiMe3)2]3 complexes (the bismuth analogue (4) has been previously reported). All four complexes possess the expected pyramidal geometries, with progressively longer M-N bond distances from P to Bi but closely similar N-M-N angles (107-104°). The structures of 1-4 also display distortions that are similar to those in f-element M[N(SiMe3)2]3 and M[CH(SiMe3)2]3 complexes, in which M···(?-Si-C) interactions have been identified. Such structural features include distorted M-(N,CH)-Si and (N,CH)-Si-C angles and close M···C and M···Si contacts. DFT calculations confirm that there are no M···(?-Si-C) interactions in 1-4; the bond distortions appear to result from the particular steric crowding that arises in pyramidal M[(N,CH)(SiMe3)2]3 complexes. This is likely the source of the most of the distortions in the structures of the f-element analogues as well, even though the latter possess attractive M···Si-C interactions. PMID:25171144

Boyde, Nicholas C; Chmely, Stephen C; Hanusa, Timothy P; Rheingold, Arnold L; Brennessel, William W

2014-09-15

287

Platinum-group element (PGE) geochemistry of Mesoarchean ultramafic-mafic cumulate rocks and chromitites from the Nuasahi Massif, Singhbhum Craton (India)  

NASA Astrophysics Data System (ADS)

The Mesoarchean Nuasahi Massif in eastern India comprises a lower ultramafic and an upper gabbro unit. The lower unit consists of orthopyroxenite, harzburgite, dunite and three chromitite bands. All of these rocks are characterized by adcumulate textures. The upper unit consists of gabbro with magnetite layers. At the contact between the eastern orthopyroxenite and the lower part of the upper gabbro, a sulfide-rich breccia zone with platinum-group-element (PGE) mineralization is present. Detailed studies of major-, trace- and PGE abundances suggest that the ultramafic-mafic cumulate rocks, chromitites and breccias are genetically linked. The chondrite-normalized U-shaped rare earth element (REE) patterns of the harzburgite resemble those of Phanerozoic boninite. The overall U-shaped REE patterns of the ultramafic rocks indicate derivation of the parental magma from a metasomatized depleted mantle source. The upper gabbros have higher relative abundances of trace elements than the lower ultramafic rocks, due to crystallization from a fractionated magma. Whole-rock geochemistry suggests that the lower ultramafic cumulate rocks with chromitites crystallized from a boninitic parental magma, whereas the upper gabbros with magnetite bands may be formed from residual boninitic magma that was contaminated by more tholeiitic-like magmas. The boninitic parental magma that crystallized to form the lower ultramafic unit was most likely generated by second-stage melting of a depleted metasomatized mantle source in a supra-subduction zone (SSZ) setting and emplaced into crustal sequences. The PGE abundances in the Nuasahi rocks provide additional constraints on their geochemical evolution during the Mesoarchean. Primitive-mantle-normalized PGE diagrams show (1) Ru enrichment in chromitites (Pd/Ru = 0.17-0.64), (2) Pd/Pt fractionation in both chromitites (Pd/Pt = 3.1) and ultramafic rocks (Pd/Pt = 0.62), (3) marked Ir depletion in ultramafic rocks (Pd/Ir = 6.3) and (4) overall PGE enrichment in chromitites (PGEtotal = 142-502 ppb). The large Ir depletion in the ultramafic rocks, and the overall Ir-depleted character of other rocks from the Nuasahi Massif, may be related to multiple episodes of melt extraction from the mantle source, giving it a subchondritic character.

Khatun, Sarifa; Mondal, Sisir K.; Zhou, Mei-Fu; Balaram, Vysetti; Prichard, Hazel M.

2014-09-01

288

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

E-print Network

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 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.

Hiroyuki Ishida; Motohiko Kusakabe; Hiroshi Okada

2014-08-11

289

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

SciTech Connect

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.

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

2010-06-01

290

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

PubMed

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

Felgueiras, Helena; Migonney, Véronique

2014-06-01

291

Platinum-group element distribution in base-metal sulfides of the UG2 chromitite, Bushveld Complex, South Africa—a reconnaissance study  

NASA Astrophysics Data System (ADS)

Two drill cores of the UG2 chromitite from the eastern and western Bushveld Complex were studied by whole-rock analysis, ore microscopy, SEM/Mineral Liberation Analysis (MLA), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. The top and base of the UG2 main seam have the highest bulk-rock Pd and Pt concentrations. Sulfides mostly occur as aggregates of pentlandite, chalcopyrite, and rare pyrrhotite and pyrite or as individual grains associated mostly with chromite grains. In situ LA-ICP-MS analyses reveal that pentlandite carries distinctly elevated platinum-group element (PGE) contents. In contrast, pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite shows average maximum values of 350-1,000 ppm Pd, 200 ppm Rh, 130-175 ppm Ru, 20 ppm Os, and 150 ppm Ir, and is the principal host of Pd and Rh in the studied ores of the UG2. Mass balance calculations were conducted for samples representing the UG2 main seam of the drill core DT46, eastern Bushveld. Pentlandite consistently hosts elevated contents of the whole-rock Pd (up to 55 %) and Rh (up to 46 %), and erratic contents of Os (up to 50 %), Ir (2 to 17 %), and Ru (1-39 %). Platinum-group mineral (PGM) investigations support these mass balance results; most of the PGM are Pt-dominant such as braggite/cooperite and Pt-Fe alloys or laurite (carrying elevated concentrations of Os and Ir). Palladium and Rh-bearing PGM are rare. Both PGE concentrations and their distribution in base-metal sulfides (BMS) in the UG2 largely resemble that of the Merensky Reef, as most of the Pd and Rh are incorporated in pentlandite, whereas pyrrhotite, chalcopyrite, and pyrite are almost devoid of PGE.

Osbahr, Inga; Oberthür, Thomas; Klemd, Reiner; Josties, Anja

2014-08-01

292

Platinum-group elements in the Morokweng impact structure, South Africa: Evidence for the impact of a large ordinary chondrite projectile at the Jurassic-Cretaceous boundary^1  

NASA Astrophysics Data System (ADS)

Radiometric dating of melt rocks at impact craters has revealed that some giant impacts appear to overlap in time with major boundaries in Earth history [e.g., the Cretaceous-Tertiary (K/T) and Jurassic-Cretaceous (J/K) boundaries]. The Morokweng impact crater in South Africa is coincident in age with the J/K boundary. However, the types of objects that generate large craters are poorly known because it is difficult to unambiguously identify the projectile from the signature it imparts into the impact rocks. Meteorites are highly enriched in the platinum-group elements (PGE), which have been widely used as a tool for identifying the presence of a meteorite signature. Here we present new PGE analyses from the Morokweng impact melt sheet. Our data reveal high PGE concentrations and high degree of PGE correlation through the melt sheet. Regression analysis was used to determine the projectile PGE signature and constrain input from the terrestrial target rocks. The closest match to Morokweng is the PGE signature of ordinary (L or LL) chondrite meteorites, which is broadly in agreement with the results of an earlier Cr isotope study. The results of these independent studies provide strong evidence that a large, ordinary chondrite projectile struck the area of Morokweng in the late Jurassic.

McDonald, I.; Andreoli, M. A. G.; Hart, R. J.; Tredoux, M.

2001-01-01

293

Systematically convergent basis sets with relativistic pseudopotentials. II. Small-core pseudopotentials and correlation consistent basis sets for the post-d group 16-18 elements  

SciTech Connect

Series of correlation consistent basis sets have been developed for the post-d group 16-18 elements in conjunction with small-core relativistic pseudopotentials (PPs) of the energy-consistent variety. The latter were adjusted to multiconfiguration Dirac-Hartree-Fock data based on the Dirac-Coulomb-Breit Hamiltonian. The outer-core (n-1)spd shells are explicitly treated together with the nsp valence shell with these PPs. The accompanying cc-pVnZ-PP and aug-cc-pVnZ-PP basis sets range in size from DZ to 5Z quality and yield systematic convergence of both Hartree-Fock and correlated total energies. In addition to the calculation of atomic electron affinities and dipole polarizabilities of the rare gas atoms, numerous molecular benchmark calculations (HBr, HI, HAt, Br2, I2, At2, SiSe, SiTe, SiPo, KrH+, XeH+, and RnH+) are also reported at the coupled cluster level of theory. For the purposes of comparison, all-electron calculations using the Douglas-Kroll-Hess Hamiltonian have also been carried out for the halogen-containing molecules using basis sets of 5Z quality.

Peterson, Kirk A.; Figgen, Detlev; Goll, Erich; Stoll, Hermann; Dolg, Michael F.

2003-12-01

294

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)

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.

Thompson David S.; Soni, Bharat K.

2001-01-01

295

Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles , V.B. Yurchyshyn1  

E-print Network

Observatory, Big Bear City, CA 92314 USA 2 Kandilli Observatory and Earthquake Research Institute, Bogazici Rome (cycles 2021) and Learmonth Solar Observatory (cycles 2223) SG numbers. All SGs recorded during the largest spot in a group, and the third one is the degree of spottedness in the group's interior (for more

296

Braid groups of imprimitive reflection groups  

E-print Network

6/5/2012 1 Braid groups of imprimitive reflection groups Ruth Corran Cap Hornu May 30, 2012 Finite complex reflection groups V a vector space over C with dim(V) = r. A complex reflection s is a non) is the reflection hyperplane for the reflection s A (finite) complex reflection group W is a (finite) group

Digne, François

297

Komatiites and nickel sulfide ores of the Black Swan area, Yilgarn Craton, Western Australia. 4. Platinum group element distribution in the ores, and genetic implications  

NASA Astrophysics Data System (ADS)

The Black Swan komatiite sequence, in the Eastern Goldfields province of the Archaean Yilgarn Craton in Western Australia, is a body of dominantly olivine-rich cumulates with lesser volumes of spinifex textured rocks, interpreted as a section through an extensive komatiite lava flow field. The sequence hosts a number of nickel sulfide orebodies, including the Silver Swan massive shoot and the Cygnet and Black Swan disseminated orebodies. The massive sulfide orebodies of the Black Swan Succession are pervasively depleted in all platinum group elements (PGEs), particularly Pt and Pd, despite very high Ni contents. This depletion cannot be explained by R-factor variations, which would also require relatively low Ni tenors. The PGE depletion could be explained in part if the ores are enriched in a monosulfide solid solution (MSS) cumulate component, but requires some additional fractional segregation of sulfide melt upstream from the site of deposition. The Silver Swan orebody shows a remarkably consistent vertical zonation in PGE contents, particularly in Ir, Ru, Rh, Os, which increase systematically from very low levels at the stratigraphic base of the sulfide body to maxima corresponding roughly with the top of a lower layer of the orebody rich in silicate inclusions. Platinum shows the opposite trend, but is somewhat modified by remobilisation during talc carbonate alteration. A similar pattern is also observed in the adjacent White Swan orebody. This zonation is interpreted and modelled as the result of fractional crystallisation of MSS from the molten sulfide pool. The strong IPGE depletion towards the base of the orebody may be a consequence of sulfide liquid crystallisation in an inverted thermal gradient, between a thin rapidly cooling upper rind of komatiite lava and a hot substrate.

Barnes, Stephen J.

2004-11-01

298

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

PubMed

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

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

2010-02-15

299

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

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

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

2014-01-01

300

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

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

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

2014-01-01

301

Practical routes to (SiH?)?P: applications in group IV semiconductor activation and in group III-V molecular synthesis.  

PubMed

The (SiH?)?P hydride is introduced as a practical source for n-doping of group IV semiconductors and as a highly-reactive delivery agent of -(SiH?)?P functionalities in exploratory synthesis. In contrast to earlier methods, the compound is produced here in high purity quantitative yields via a new single-step method based on reactions of SiH?Br and (Me?Sn)?P, circumventing the need for toxic and unstable starting materials. As an initial demonstration of its utility we synthesized monosubstituted Me?M-P(SiH?)? (M = Al, Ga, In) derivatives of Me?M containing the (SiH?)?P ligand for the first time, in analogy to the known Me?M-P(SiMe?)? counterparts. A dimeric structure of Me?M-P(SiH?)? is proposed on the basis of spectroscopic characterizations and quantum chemical simulations. Next, in the context of materials synthesis, the (SiH?)?P compound was used to dope germanium for the first time by building a prototype p(++)Si(100)/i-Ge/n-Ge photodiode structure. The resultant n-type Ge layers contained active carrier concentrations of 3-4 × 10¹? atoms cm?³ as determined by spectroscopic ellipsometry and confirmed by SIMS. Strain analysis using high resolution XRD yielded a Si content of 4 × 10²? atoms cm?³ in agreement with SIMS and within the range expected for incorporating Si?P type units into the diamond cubic Ge matrix. Extensive characterizations for structure, morphology and crystallinity indicate that the Si co-dopant plays essentially a passive role and does not compromise the device quality of the host material nor does it fundamentally alter its optical properties. PMID:20379588

Tice, Jesse B; Chizmeshya, A V G; Tolle, J; D' Costa, V R; Menendez, J; Kouvetakis, J

2010-05-21

302

A database of chondrite analyses including platinum group elements, Ni, Co, Au, and Cr: Implications for the identification of chondritic projectiles  

Microsoft Academic Search

Siderophile elements have been used to constrain projectile compositions in terrestrial and lunar impact melt rocks. To obtain a better knowledge of compositional differences between potential chondritic projectile types, meteorite analyses of the elements Ru, Rh, Pd, Os, Ir, Pt, Cr, Co, Ni, and Au were gathered into a database. The presented compilation comprises 806 analyses of 278 chondrites including

Roald Tagle; Jana Berlin

2008-01-01

303

The distribution of platinum group elements (PGE) and other chalcophile elements among sulfides from the Creighton Ni-Cu-PGE sulfide deposit, Sudbury, Canada, and the origin of palladium in pentlandite  

NASA Astrophysics Data System (ADS)

Concentrations of platinum group elements (PGE), Ag, As, Au, Bi, Cd, Co, Mo, Pb, Re, Sb, Se, Sn, Te, and Zn, have been determined in base metal sulfide (BMS) minerals from the western branch (402 Trough orebodies) of the Creighton Ni-Cu-PGE sulfide deposit, Sudbury, Canada. The sulfide assemblage is dominated by pyrrhotite, with minor pentlandite, chalcopyrite, and pyrite, and they represent monosulfide solid solution (MSS) cumulates. The aim of this study was to establish the distribution of the PGE among the BMS and platinum group minerals (PGM) in order to understand better the petrogenesis of the deposit. Mass balance calculations show that the BMS host all of the Co and Se, a significant proportion (40-90%) of Os, Pd, Ru, Cd, Sn, and Zn, but very little (<35%) of the Ag, Au, Bi, Ir, Mo, Pb, Pt, Rh, Re, Sb, and Te. Osmium and Ru are concentrated in equal proportions in pyrrhotite, pentlandite, and pyrite. Cobalt and Pd (˜1 ppm) are concentrated in pentlandite. Silver, Cd, Sn, Zn, and in rare cases Au and Te, are concentrated in chalcopyrite. Selenium is present in equal proportions in all three BMS. Iridium, Rh, and Pt are present in euhedrally zoned PGE sulfarsenides, which comprise irarsite (IrAsS), hollingworthite (RhAsS), PGE-Ni-rich cobaltite (CoAsS), and subordinate sperrylite (PtAs2), all of which are hosted predominantly in pyrrhotite and pentlandite. Silver, Au, Bi, Mo, Pb, Re, Sb, and Te are found predominantly in discrete accessory minerals such as electrum (Au-Ag alloy), hessite (Ag2Te), michenerite (PdBiTe), and rhenium sulfides. The enrichment of Os, Ru, Ni, and Co in pyrrhotite, pentlandite, and pyrite and Ag, Au, Cd, Sn, Te, and Zn in chalcopyrite can be explained by fractional crystallization of MSS from a sulfide liquid followed by exsolution of the sulfides. The early crystallization of the PGE sulfarsenides from the sulfide melt depleted the MSS in Ir and Rh. The bulk of Pd in pentlandite cannot be explained by sulfide fractionation alone because Pd should have partitioned into the residual Cu-rich liquid and be in chalcopyrite or in PGM around chalcopyrite. The variation of Pd among different pentlandite textures provides evidence that Pd diffuses into pentlandite during its exsolution from MSS. The source of Pd was from the small quantity of Pd that partitioned originally into the MSS and a larger quantity of Pd in the nearby Cu-rich portion (intermediate solid solution and/or Pd-bearing PGM). The source of Pd became depleted during the diffusion process, thus later-forming pentlandite (rims of coarse-granular, veinlets, and exsolution flames) contains less Pd than early-forming pentlandite (cores of coarse-granular).

Dare, Sarah A. S.; Barnes, Sarah-Jane; Prichard, Hazel M.

2010-12-01

304

Prevalence of Group B Streptococcus serotypes III and V in pregnant women of Rio de Janeiro, Brazil  

PubMed Central

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

Soares, Georgia Cristina Tavolaro; Alviano, Daniela Sales; da Silva Santos, Gabriela; Alviano, Celuta Sales; Mattos-Guaraldi, Ana Luiza; Nagao, Prescilla Emy

2013-01-01

305

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)

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.

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

2003-01-01

306

Time Distributions of Large and Small Sunspot Groups Over Four Solar Cycles , V.B. Yurchyshyn1  

E-print Network

Observatory, Big Bear City, CA 92314 USA 2 Kandilli Observatory and Earthquake Research Institute, Bogazici Rome (cycles 2021) and Learmonth Solar Observatory (cycles 2223) SG numbers. All SGs recorded during paper), the second component describes the largest spot in a group, and the third one is the degree

Yurchyshyn, Vasyl

307

Multipole Matrix Elements v for H-Like Atoms and Their Applications (as ? = 1, n ? 4, Enl < 0 ? E ? 1)  

NASA Astrophysics Data System (ADS)

This article deals with the connection between multipole matrix elements ? and ? for H-like atoms, where ? is the so-called "auxiliary" parameter of Heun's differential equation and ˜ {Z}=Z/? is the "effective" nuclear charge, and new properties of Appell's function F2(x,y) to the vicinity of the singular point (1, 1) and in addition, here, first V. A. Fock's idea for the continuous spectrum is taken into consideration. Such an approach allows us to get the explicit expressions for squares of the dipole moments and the certain physical characteristics in atomic physics and also their exact numerical values, e.g., the average oscillator strengths bar {f}(nl,El') and the line intensities J(nl, El'), etc., as n ? 4, l'= l ± 1 and 0 ? E ? 1 (see Tables 1-3). Besides, diagrams of certain radial functions for the discrete-continuous transitions are given here.

Tarasov, V. F.

308

Detection of secondary structure-based regulatory nucleotide elements The trypanosomatids are a monophyletic sub-group of excavate parasites [1,2] which  

E-print Network

of the trypanosomatid group cause globally important parasitic diseases of humans including sleeping sickness, Chagas information-rich methods (for example [22,23]), which utilise groups of co-regulated or functionally related

Goldschmidt, Christina

309

A new mixed group 5 metal selenide, Nb1.41V0.59Se9  

PubMed Central

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

Lee, Eunsil; Yun, Hoseop

2011-01-01

310

Perforin polymorphism A91V and susceptibility to B-precursor childhood acute lymphoblastic leukemia: a report from the Children’s Oncology Group  

PubMed Central

Perforin plays a key role in the cytotoxicity of natural killer and cytotoxic T cells. Genetic mutations in the perforin gene (PRF1) give rise to approximately 30% cases of familial hemophagocytic lymphohistiocytosis. A frequent polymorphism, A91V (C to T transition at position 272), may impair processing of perforin protein to the active form, and has been suggested to increase susceptibility to childhood acute lymphoblastic leukemia (ALL). To investigate the role of A91V in ALL, we genotyped 2272 children with de novo ALL registered on the Pediatric Oncology Group ALL Classification study P9900 and 655 normal controls. Allele frequencies in the controls showed a very low frequency of the variant allele in blacks, 0.7% compared to 4% in white controls. In light of this, analysis was restricted to a comparison of white cases and controls only. Overall genotype frequencies were similar in white ALL cases and normal white controls (P = 0.58), indicating that in contrast to the previous report, A91V polymorphism is not associated with increased risk of childhood ALL. PRF1 A91V frequency was significantly increased in children with BCR-ABL positive ALL (24 vs 8.5%; P = 0.0048); however, this observation includes a relatively small number of cases and needs further exploration. PMID:16791263

Mehta, PA; Davies, SM; Kumar, A; Devidas, M; Lee, S; Zamzow, T; Elliott, J; Villanueva, J; Pullen, J; Zewge, Y; Filipovich, A

2010-01-01

311

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 ...

312

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

NASA Astrophysics Data System (ADS)

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 calculated Stoner enhancement factor S for CrN indicates that the paramagnetic state is unstable with respect to ferromagnetism, consistent with the known antiferromagnetism in this compound. The calculated value of S=2.15 for MoN is not large enough to provide a serious impediment to superconductivity. The superconducting properties are evaluated within the Gaspari-Gyorffy theory for the electron-phonon coupling constant ?, calculated to be ~1.6 in MoN (about 60% larger than in NbN). The problem of stabilizing the metastable B1 structure over the thermodynamically more stable hexagonal MoN material is considered.

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

1985-01-01

313

Geochemistry of trace elements in coals from the Zhuji Mine, Huainan Coalfield, Anhui, China  

USGS Publications Warehouse

The abundances of nine major elements and thirty-eight trace elements in 520 samples of low sulfur coals from the Zhuji Mine, Huainan Coalfield, Anhui, China, were determined. Samples were mainly collected from 10 minable coal seams of 29 boreholes during exploration. The B content in coals shows that the influence of brackish water decreased toward the top of coal seams; marine transgression and regression occurred frequently in the Lower Shihezi Formation. A wide range of elemental abundances is found. Weighted means of Na, K, Fe, P, Be, B, Co, Ni, Cr, Se, Sb, Ba, and Bi abundances in Zhuji coals are higher, and the remainder elements are either lower or equal to the average values of elements in coals of northern China. Compared to the Chinese coals, the Zhuji coals are higher in Na, K, Be, B, Cr, Co, Se, Sn, Sb, and Bi, but lower in Ti, P, Li, V and Zn. The Zhuji coals are lower only in S, P, V and Zn than average U.S. and world coals. Potassium, Mg, Ca, Mn, Sr, As, Se, Sb and light rare earth elements (LREE) had a tendency to be enriched in thicker coal seams, whereas Fe, Ti, P, V, Co, Ni, Y, Mo, Pb and heavy rare earth elements (HREE) were inclined to concentrate in thinner coal seams. The enrichment of some elements in the Shanxi or Upper Shihezi Formations is related to their depositional environments. The elements are classified into three groups based on their stratigraphic distributions from coal seams 3 to 11-2, and the characteristics of each group are discussed. Lateral distributions of selected elements are also investigated. The correlation coefficients of elemental abundances with ash content show that the elements may be classified into four groups related to modes of occurrence of these elements. ?? 2009 Elsevier B.V. All rights reserved.

Sun, R.; Liu, G.; Zheng, L.; Chou, C.-L.

2010-01-01

314

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

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

B. M. Gibbs; D. Thompson; B. B. Argent

2008-01-01

315

CNO abundances in H II regions of the Magellanic clouds and the galaxy with implications regarding the nucleosynthesis of the CNO element group  

NASA Technical Reports Server (NTRS)

Final abundance results of IUE observations of the UV spectra of three H II regions in the Small Magellanic Cloud and four H II regions in the Large Magellanic Cloud are presented. Calculated yields of carbon and oxygen derived are y(C)=.00063 and y(O)=.0016. The nucleosynthetic origin of nitrogen was evaluated as being predominantly a secondary element produced from carbon as its seed. Plotting log N/C versus log C/H yielded the rather unexpected result that log N/C decreases with lo C/H over the SMC-LMC-Orion range. The cause of this relationship is discussed.

Dufour, R. J.; Shields, G. A.

1982-01-01

316

Elemental abundance analyses with coadded DAO spectrograms. IV - Revision of previous analyses. V - The mercury-manganese stars Phi Herculis, 28 Herculis and HR 7664  

NASA Technical Reports Server (NTRS)

Changes in chromium, manganese, and nickel abundances derived from singly ionized lines are incorporated into the elemental abundance of Adelman and Hill (1987) in order to provide more accurate gf values and damping constants for several atomic species. An improved agreement with the values from neutral lines of the same element is found. In the second part, the method is applied to an elemental abundance analysis of three mercury-manganese stars, and correlations are found between the derived abundances and the effective temperature.

Adelman, Saul J.

1988-01-01

317

Separation of transplutonium elements.  

PubMed

A critical review of the group separation of tervalent lanthanides and actinides and of the separation of individual transplutonium elements is presented. The theoretical principles involved are also discussed. PMID:18959895

Starý, J

1966-03-01

318

American Elements  

NSDL National Science Digital Library

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.

2006-02-27

319

Chemical Elements  

NSDL National Science Digital Library

To find quick facts on elements The Photographic Periodic Table of Elements-shows a photograhpic representation of most of the elements (remember some are invisible gases) The Element Song Click on the following links to find quick facts about the elements and peridoic table: Periodic Table of Elements: LANL - Originally this resource, the Periodic Table, was created by Robert Husted at Los Alamos National Laboratory during his time ...

Schultz, Ms.

2007-03-08

320

Elemental diffusion during the droplet epitaxy growth of In(Ga)As/GaAs(001) quantum dots by metal-organic chemical vapor deposition  

SciTech Connect

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.

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

321

Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue - VII. V1200 Centauri: a bright triple in the Hyades moving group  

E-print Network

We present the orbital and physical parameters of the detached eclipsing binary V1200~Centauri (ASAS~J135218-3837.3) from the analysis of spectroscopic observations and light curves from the \\textit{All Sky Automated Survey} (ASAS) and SuperWASP database. The radial velocities were computed from the high-resolution spectra obtained with the OUC 50-cm telescope and PUCHEROS spectrograph and with 1.2m Euler telescope and CORALIE spectrograph using the cross-correlation technique \\textsc{todcor}. We found that the absolute parameters of the system are $M_1= 1.394\\pm 0.030$ M$_\\odot$, $M_2= 0.866\\pm 0.015$ M$_\\odot$, $R_1= 1.39\\pm 0.15$ R$_\\odot$, $R_2= 1.10\\pm 0.25$ R$_\\odot$. We investigated the evolutionary status and kinematics of the binary and our results indicate that V1200~Centauri is likely a member of the Hyades moving group, but the largely inflated secondary's radius may suggest that the system may be even younger, around 30 Myr. We also found that the eclipsing pair is orbited by another, stellar-mas...

Coronado, J; Vanzi, L; Espinoza, N; Brahm, R; Jordán, A; Catelán, M; Ratajczak, M; Konacki, M

2015-01-01

322

Solubility and transport of platinum-group elements in supercritical fluids: Summary and estimates of thermodynamic properties for ruthenium, rhodium, palladium, and platinum solids, aqueous ions, and complexes to 1000 C and 5 kbar  

SciTech Connect

Several correlation methods are used to estimate data and equation-of-state parameters that permit calculation of standard state thermodynamic properties at high pressures and temperatures for metals, oxides, and sulfides, as well as ions, and aqueous chloride, hydroxide, and sulfate complexes of Ru{sup +2}, Ru{sup +3}, Rh{sup +2}, Rh{sup +3}, Pd{sup +2}, and Pt{sup +2}. Estimates are based on a critical review of data from the literature at 25 C and 1 bar. The combined data for 14 minerals, 6 cations, and 56 aqueous complexes provide a foundation for quantitative predictions of aqueous speciation of these platinum group elements (PGE), as well as platinum group mineral (PGM) solubilities as functions of pH, oxidation state, and chloride and sulfate content of geologic fluids at temperatures to 1000 C and pressures to 5 kbar. Therefore, these estimates are the first to address PGE speciation at the pressure and temperatures of most PGM deposits. Comparisons are made to other theoretical predictions of platinum-group element (PGE) complex formation in aqueous solutions and to pertinent experimental data. The authors conclude that Pd-chloride complexes may be less stable at lower temperatures than previously predicted by other investigators, but that Pt-chloride complexes may be considerably more stable.

Sassani, D.C.; Shock, E.L. [Washington Univ., St. Louis, MO (United States). Dept. of Earth and Planetary Science] [Washington Univ., St. Louis, MO (United States). Dept. of Earth and Planetary Science

1998-08-01

323

Nitrogen-containing mixed group-V compounds grown by gas-source molecular beam epitaxy using a nitrogen radical beam source  

NASA Astrophysics Data System (ADS)

This dissertation is devoted to the investigation of a not yet well studied material family--nitrogen-containing mixed group-V compounds--in order to explore novel properties that may be useful in designing novel devices or improving existing devices. Many obstacles exist, however, in realizing these mixed group V alloys, such as a large miscibility gap and a small N solubility in III-V binaries. These issues are investigated by studying N incorporation in InP, GaP, and GaAs by gas-source molecular beam epitaxy using a nitrogen radical beam source. The results indicate that the problem of low solubility of N in III-Vs can be overcome by low temperature growth, and that record N incorporation in InP, GaP, and GaAs has been achieved. Our studies also demonstrate that although an extremely large miscibility gap exists for these materials, phase-separation can be avoided by lowering the growth temperature, which is attributed to the fact that metastable alloys without decomposition can be formed by using non-equilibrium growth techniques at low growth temperatures. Strong red shift instead of blue shift of bandgap energy is found as the N composition is increased, but no semimetallic region seems to exist, contrary to predictions based on Van Vecthen's model. Furthermore, a composition-dependent bowing parameter is observed for GaNAs, which is consistent with first-principle supercell calculations and is attributed to the formation of impurity-like and band-like states in the alloy. The second part of this dissertation explores another interesting area--bandgap engineering using N concentration as a new parameter. The first section of this part focuses on improving the interface quality of InGaAs/InGaAsP QW structures for fabricating microdisk lasers with improved performance. These lasers serve as the basis for comparing with those made from the novel material system InNAsP/InGaAsP developed in the second section of this part. The results demonstrate that high-quality InNAsP/InGaAsP strained QW structures can be achieved, and that microdisk lasers made out of this novel material system possess improved high-temperature performance due to increased electron confinement.

Bi, Wengang

324

Hydrogenation decomposition desorption recombination magnets based on Sm2 + delta Fe17M0.4 carbonitrides (M=IVB/VB/VIB group elements)  

NASA Astrophysics Data System (ADS)

The hydrogenation decomposition desorption recombination (HDDR) process is carried out to produce permanent magnets based on Sm2+?Fe17M0.4 carbonitrides, where M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W; and ??0.6. It is found that minor additions of M significantly reduce the amounts of ?-Fe and SmFe3 in the starting materials. The best isotropic HDDR magnet obtained is for M=Ti, which has an intrinsic coercivity of 18 kOe and an energy product of 9.8 MGOe at room temperature.

Chen, X.; Altounian, Z.

1994-05-01

325

Understanding Elements  

NSDL National Science Digital Library

Students examine the periodic table and the properties of elements. They learn the basic definition of an element and the 18 elements that compose most of the matter in the universe. The periodic table is described as one method of organization for the elements. The concepts of physical and chemical properties are also reviewed.

Integrated Teaching And Learning Program

326

Plane Groups  

NSDL National Science Digital Library

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.

Perkins, Dexter

327

Effective Group Counseling.  

ERIC Educational Resources Information Center

This book focuses on the essential elements of leading effective groups in group counseling. Chapter 1 concentrates on the rationale behind using groups and their myths, advantages, and limitations. Chapter 2 discusses different types of groups, especially those that are therapeutic and task-oriented, and their theory and ethics. Chapter 3 delves…

Gladding, Samuel T.

328

Transpositionally active episomal hAT elements  

Microsoft Academic Search

BACKGROUND: hAT elements and V(D)J recombination may have evolved from a common ancestral transposable element system. Extrachromosomal, circular forms of transposable elements (referred to here as episomal forms) have been reported yet their biological significance remains unknown. V(D)J signal joints, which resemble episomal transposable elements, have been considered non-recombinogenic products of V(D)J recombination and a safe way to dispose of

David A O'Brochta; Christina D Stosic; Kristina Pilitt; Ramanand A Subramanian; Robert H Hice; Peter W Atkinson

2009-01-01

329

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)

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.

Righter, Kevin

2008-01-01

330

NASA Constellation Program (CxP) Key Driving Requirements and Element Descriptions for International Architecture Working Group (IAWG) Functional Teams Human Transportation Cargo Transportation  

NASA Technical Reports Server (NTRS)

The NASA Constellation uncrewed cargo mission delivers cargo to any designated location on the lunar surface (or other staging point) in a single mission. This capability is used to deliver surface infrastructure needed for lunar outpost construction, to provide periodic logistics resupply to support a continuous human lunar presence, and potentially deliver other assets to various locations.In the nominal mission mode, the Altair lunar lander is launched on Ares V into Low Earth Orbit (LEO), following a short Low Earth Orbit (LEO) loiter period, the Earth Departure Stage (EDS) performs the Trans Lunar Injection (TLI) burn and is then jettisoned. The Altair performs translunar trajectory correction maneuvers as necessary and performs the Lunar Orbit Insertion (LOI) burn. Altair then descends to the surface to land near a designated target, presumably in proximity to an Outpost location or another site of interest for exploration.Alternatively, the EDS and Altair Descent Stage could deliver assets to various staging points within their propulsive capabilities.

Martinez, Roland M.

2009-01-01

331

Convex sublattice subgroups of free Abelian lattice-ordered groups: an application of simplicial geometry  

E-print Network

by 1, . . . , n (please see [1]). Moreover, each element of An is a finite meet of a finite join geometry A. M. W. Glass At the Conference at Erlogol in June 2001, I was surprised to discover from V. M of a finitely generated free Abelian lattice-ordered group could ever be a free Abelian lattice-ordered group

Glass, A.

332

Large-signal characterizations of DDR IMPATT devices based on group III-V semiconductors at millimeter-wave and terahertz frequencies  

NASA Astrophysics Data System (ADS)

Large-signal (L-S) characterizations of double-drift region (DDR) impact avalanche transit time (IMPATT) devices based on group III-V semiconductors such as wurtzite (Wz) GaN, GaAs and InP have been carried out at both millimeter-wave (mm-wave) and terahertz (THz) frequency bands. A L-S simulation technique based on a non-sinusoidal voltage excitation (NSVE) model developed by the authors has been used to obtain the high frequency properties of the above mentioned devices. The effect of band-to-band tunneling on the L-S properties of the device at different mm-wave and THz frequencies are also investigated. Similar studies are also carried out for DDR IMPATTs based on the most popular semiconductor material, i.e. Si, for the sake of comparison. A comparative study of the devices based on conventional semiconductor materials (i.e. GaAs, InP and Si) with those based on Wz-GaN shows significantly better performance capabilities of the latter at both mm-wave and THz frequencies.

Acharyya, Aritra; Mallik, Aliva; Banerjee, Debopriya; Ganguli, Suman; Das, Arindam; Dasgupta, Sudeepto; Banerjee, J. P.

2014-08-01

333

Chemical Elements: An Online Interactive Periodic Table  

NSDL National Science Digital Library

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 particular element are given in some cases. Citation information is also provided.

Bentor, Yinon

2009-01-01

334

A Measurement of the Top Quark Mass with the D0 Detector at s**(1/2) = 1.96-TeV using the Matrix Element Method  

SciTech Connect

Using a data set of 158 and 169 pb{sup -1} of D0 Run-II data in the electron and muon plus jets channel, respectively, the top quark mass has been measured using the Matrix Element Method. The method and its implementation are described. Its performance is studied in Monte Carlo using ensemble tests and the method is applied to the Moriond 2004 data set.

Kroeninger, Kevin Alexander; /Bonn U.

2004-04-01

335

Element Research  

NSDL National Science Digital Library

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 - ...

Wall, Mr.

2008-12-09

336

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...

337

Ring-laser gyroscope system using dispersive element(s)  

NASA Technical Reports Server (NTRS)

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.

Smith, David D. (Inventor)

2010-01-01

338

Energy spectra of elements with 18 less than or equal to Z less than or equal to 28 between 10 and 300 GeV/amu  

NASA Technical Reports Server (NTRS)

The HEAO-3 Heavy Nuclei Experiment is composed of ionization chambers above and below a plastic Cherenkov counter. The energy dependence of the abundances of elements with atomic number, Z, between 18 and 28 were measured at very high energies where they are rare and thus need the large area x time of this experiment. The measurements of the Danish-French HEAO-3 experiment were extended to higher energies, using the relativistic rise of ionization signal as a measure of energy, and determine source abundances for Ar and Ca.

Jones, M. D.; Klarmann, J.; Stone, E. C.; Waddington, C. J.; Binns, W. R.; Garrard, T. L.; Israel, M. H.

1985-01-01

339

Group 12 Elements and Their Small Clusters:. Electric Dipole Polarizability of Zn, cd and Hg, Zn2 Dimer and Higher Znn Microclusters and Neutral, Cationic and Anionic Zinc Oxide Molecules (ZnO, ZnO+ and ZnO-)  

NASA Astrophysics Data System (ADS)

This review is in general about group 12 elements and their small microclusters. In this part, after presenting an extensive literature survey of the electric dipole polarizability studies of the Zn, Cd and Hg atoms, we specifically target zinc-containing small clusters, beginning with the Zn2 dimer, the Zn3 trimer, higher Znn clusters and the neutral, cationic and anionic zinc oxide clusters: ZnO, ZnO+ and ZnO-. We tabulated experimental and theoretical results for the spectroscopic constants (dissociation energy De or D0, bond length re, fundamental frequency we, anharmonicity constant wexe and dipole moment ?e) of the diatomic clusters and the first and second ionization potentials IP1 and IP2 and electron affinity EA of the species reviewed.

Oymak, Hüseyin; Erkoç, ?akir

340

Solvent Refined Coal (SRC) process: trace elements. Volume III. Pilot plant development work. Part 6. Fate of trace elements in the SRC process. [Ph. D. Thesis  

SciTech Connect

A study of the forms of trace elements occurring in Solvent Refined Coal has been performed by chemical separation of the Solvent Refined Coal based on differences in the functionality and molecular weight of the organic matrix. Analysis of the fractions separated for various trace elements has revealed associations of certain elements with other elements as well as with certain fractions. The analysis of Solvent Refined Coal I by these methods provided data on the distribution of Ti, V, Ca, S, Al, Mn, As, Se, Cr, Fe, Ni, Zn, Sc, and Ga in the fractions generated. Because of the low trace element content of Solvent Refined Coal II only As, Se, and Cr could be detected in the silica fractions. Based on the distributions three different groups of elements have been based on the association of elements with each other and with certain fractions. The first group is composed of As, Se, and Cr associated with silica fractions of relatively low functionality; these elements have a high percent solubility in the starting Solvent Refined Coal II oil. The second group composed of Ti, V, and to a lesser extent a second form of Cr, is associated with fractions that have a high concentration of phenolic material and is probably present as phenoxide complexes. The third group composed of Fe, Ca, K, Al, and Mg is associated with the most functional fractions and is possibly present as humic acid type complexes or as submicron size particulates. The integration of chromatographic methods with trace element analysis of the fractions generated is capable of discerning the presence of different forms of the elements. The methods used are applicable to other important geologically occurring organic matter.

Weiss, C.S.

1980-09-01

341

M X-ray cross sections from 75 to 300 keV proton bombardment of selected 5d transition elements  

NASA Astrophysics Data System (ADS)

M X-ray production cross sections for selected thick targets of Hf, W, Re, Pt, Au and Pb impacted by 75-300 keV protons are presented and compared with ECPSSR and RPWBA theories using different atomic data bases, including comparisons with other investigators. The results for the major M X-ray transitions exhibit a universal character with respect to the reduced proton velocity in agreement with expectations from theory.

Cipolla, Sam J.

2014-07-01

342

Energy dependence of photon-induced K? and K? x-ray production cross-sections for some elements with 38?Z?51 in the energy range 20-50 keV  

NASA Astrophysics Data System (ADS)

The energy dependence of photon-induced K? and K? x-ray production (or x-ray fluorescence) cross-sections for Sr, Y, Mo, Ru, Pd, Ag, In and Sb elements has been studied in the energy range of 20-50 keV using Energy Dispersive X-Ray Fluorescence (EDXRF) Spectrometry. The photon energy dependence of K x-ray production cross-sections was measured with secondary excitation method. A radioisotope point source of 241Am was employed to excite the K x-rays of secondary exciter elements. The L x-ray yields from Th and U were measured to determine IoG (the intensity of exciter K x-rays falling on primary target). The measurements have been made by observing the x-ray emissions with the help of HPGe detector coupled with a multichannel analyzer. The areas of the K? and K? spectral peaks, as well as the net peak areas, have been determined by a fitting process. The measured K? and K? x-ray production cross-sections have been compared with calculated theoretical values in this energy regime. The present experimental results for all the elements were in general agreement with the theoretical values calculated using photoionization cross-sections, fractional rates (based on Hartree-Slater potentials) and fluorescence yields.

Seven, Sabriye

2012-05-01

343

Measurement of the t-Channel Single-Top-Quark Production Cross Section and of the |V[subscript tb]| CKM Matrix Element in Pp Collisions at ?s = 8 TeV  

E-print Network

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 ...

Apyan, Aram

344

Solar cosmic ray composition above 10 MeV/nucleon and its energy dependence in the 4 August 1972 event. [including proton, helium, and Fe-group nuclei fluxes  

NASA Technical Reports Server (NTRS)

Observations of the proton, helium (C,N,O) and Fe-group nuclei fluxes made during the large 4 August 1972 solar particle event are presented. The results show a small, but significant variation of the composition of multicharged nuclei as a function of energy in the energy region above 10 MeV/nucleon. In particular, the He/(C,N,O) abundance ratio varies by a factor approximately 2 between 10 and 50 MeV/nucleon, and the Fe-group/(C,N,O) ratio suggests a similar variation. Abundance ratios from the 4 August 1972 event are compared as a function of energy with ratios measured in other solar events. At energies approximately greater than 50 MeV/nucleon, the He/(C,N,O) abundance ratio for August 1972 is consistent with all earlier measurements made above that energy.

Bertsch, D. L.; Biswas, S.; Reames, D. V.

1974-01-01

345

[Spectral interferences of rare earth elements observed with a high resolution inductively coupled plasma atomic emission spectrometer. V. Spectral interferences of lutetium, thulium, yttrium and ytterbium as matrices].  

PubMed

The spectral interferences of Lu, Tm, Y and Yb (100 microns.mL-1, separately) as matrices on the other REEs (1 or 5 microns.mL-1) were observed with a high resolution ICP-AES with a grating of 3,600 grooves.mm-1. Totally 66 analytical lines of 15 REEs were selected as the prominent lines for spectral interference studies. The "Q" values and "the true detection limit" were calculated for the selected prominent lines with the exist of the four matrix elements. The obtained information is useful in the selection of the best analytical lines for the determination of REEs in the other REEs' matrices. PMID:12953494

Sun, Z; Gu, S; Sun, D; Wang, X; Li, B

2000-04-01

346

Present day pacemakers for pulse generator exchange: is 3.5 V a sufficient nominal setting for the pulse amplitude? Thera Pacemaker Study Group.  

PubMed

Projected pacemaker longevity is calculated according to the nominal setting, which is 3.5 V for pulse amplitude in most present day pacemakers. The aim of this study was to test whether the nominal ventricular output setting of 3.5 V and 0.4 ms provides a 100% safety margin if these pacemakers are connected to implanted ventricular pacing leads. The study included 24 patients undergoing pulse generator exchange. The new pacemaker was either a Thera DR (n = 21) or Thera SR (n = 3) device. Ventricular pacing leads were implanted 70 +/- 38 months previously. Intraoperative measurements included pacing threshold at 0.5-ms pulse duration, impedance, and R wave amplitude. To achieve a 100% safety margin with 3.5 V, the cut-off pacing threshold is 1.7 V. At discharge it was assessed whether ventricular pulse amplitude remained at < or = 3.5 V or was programmed to > 3.5 V. At pulse generator exchange, pacing threshold was 1.2 +/- 0.5 V, including four patients with pacing thresholds > 1.7 V. Impedance was 587 +/- 189 omega and R wave amplitude was 12.8 +/- 4.8 mV. At discharge, ventricular pulse amplitude remained at the nominal setting in 13 patients, including 2 patients with high pacing thresholds at pacemaker exchange, and was programmed to < 3.5 V in 7 patients. Ventricular pulse amplitude was programmed to > 3.5 V in four patients. Two of these patients had high pacing thresholds (> 1.7 V/0.5 ms) at pulse generator exchange; the other two patients were programmed to > 3.5 V, although 3.5 V already provided a 100% safety margin. After pulse generator exchange, 92% of the patients could be paced with a 3.5-V pulse amplitude. Pacemakers were programmed in four patients > 3.5 V, but in only two of them to obtain a sufficient safety margin. High pacing thresholds at pulse generator exchange did not generally predict high pacing thresholds at discharge. PMID:8945049

Schuchert, A; Van Langen, H; Michels, K; Meinertz, T

1996-11-01

347

Top Quark Mass Measurement in the tt-bar All Hadronic Channel using a Matrix Element Technique in ppbar Collisions at sqrt s = 1.96 TeV  

E-print Network

We present a measurement of the top quark mass in the all-hadronic channel (\\tt $\\to$ \\bb$q_{1}\\bar{q_{2}}q_{3}\\bar{q_{4}}$) using 943 pb$^{-1}$ of \\ppbar collisions at $\\sqrt {s} = 1.96$ TeV collected at the CDF II detector at Fermilab (CDF). We apply the standard model production and decay matrix-element (ME) to $\\ttbar$ 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 $\\pm$ 3.7 (stat.+JES) $\\pm$ 2.1 (syst.) GeV/$c^{2}$. The combined uncertainty on the top quark mass is 4.3 GeV/$c^{2}$.

CDF Collaboration; T. Aaltonen

2008-11-06

348

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni  

NASA Astrophysics Data System (ADS)

Context. Rapid advancements in light-curve and radial-velocity curve modelling, as well as improvements in the accuracy of observations, allow more stringent tests of the theory of stellar evolution. Binaries with rapid apsidal advance are particularly useful in this respect since the internal structure of the stars can also be tested. Aims: Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cygrepresents one of the cornerstones of critical tests of stellar evolutionary theory for massive stars. Nevertheless, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyse all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude. Methods: We obtained new series of UBV observations at three observatories separated in local time to obtain complete light curves of Y Cygfor its orbital period close to 3 days. This new photometry was reduced and carefully transformed to the standard UBV system using the HEC22 program. We also obtained new series of red spectra secured at two observatories and re-analysed earlier obtained blue electronic spectra. Reduction of the new spectra was carried out in the IRAF and SPEFO programs. Orbital elements were derived independently with the FOTEL and PHOEBE programs and via disentangling with the program KOREL . The final combined solution was obtained with the program PHOEBE . Results: Our analyses provide the most accurate value of the apsidal period of (47.805 ± 0.030) yr published so far and the following physical elements: M1 = 17.72 ± 0.35 M?, M2 = 17.73 ± 0.30 M?, R1 = 5.785 ± 0.091 R?, and R2 = 5.816 ± 0.063 R?. The disentangling thus resulted in the masses, which are somewhat higher than all previous determinations and virtually the same for both stars, while the light curve implies a slighly higher radius and luminosity for star 2. The above empirical values imply the logarithm of the internal structure constant log k2 = -1.937. A comparison with Claret's stellar interior models implies an age close to 2 × 106 yr for both stars. Conclusions: The claimed accuracy of modern element determination of 1-2 per cent still seems a bit too optimistic and obtaining new high-dispersion and high-resolution spectra is desirable. Based on new spectral and photometric observations from the following observatories: Dominion Astrophysical Observatory, Hvar, Ond?ejov, Fairborn, and Sejong.Appendix A is available in electronic form at http://www.aanda.orgTables 4 and 5 are 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/563/A120

Harmanec, P.; Holmgren, D. E.; Wolf, M.; Boži?, H.; Guinan, E. F.; Kang, Y. W.; Mayer, P.; McCook, G. P.; Nemravová, J.; Yang, S.; Šlechta, M.; Ruždjak, D.; Sudar, D.; Svoboda, P.

2014-03-01

349

Elemental health  

SciTech Connect

Trace elements used in nutritional supplements and vitamins are discussed in the article. Relevant studies are briefly cited regarding the health effects of selenium, chromium, germanium, silicon, zinc, magnesium, silver, manganese, ruthenium, lithium, and vanadium. The toxicity and food sources are listed for some of the elements. A brief summary is also provided of the nutritional supplements market.

Tonneson, L.C.

1997-01-01

350

Platinum-group element (PGE) geochemistry of Deccan orangeites, Bastar craton, central India: Implication for a non-terrestrial origin for iridium enrichment at the K-Pg boundary  

NASA Astrophysics Data System (ADS)

We report platinum group element (PGE) concentrations of twelve bulk-rock samples from the Behradih and Kodomali orangeite intrusions in the Mainpur field, Bastar craton, central India, which are emplaced synchronously with the Deccan flood basalts. Their palladium-group PGE (PPGE) (1.8-5.2 ppb Pt, 1.2-6.4 ppb Pd) contents are distinctly higher compared to their iridium-group PGE (IPGE) concentrations (0.8-2 ppb Os, 0.8-1.2 ppb Ir, 3.2-4.2 ppb Ru, and 0.2-0.8 ppb Rh). Their PGE contents as well as Pd/Ir ratios are either similar or even lower than those from the Mesoproterozoic and Cretaceous kimberlites and orangeites from the Kaapvaal craton (southern Africa), Cretaceous kimberlites from the Sao Fransisco craton (Brazil), Ordovician kimberlites from the North China craton and the Mesoproterozoic southern Indian kimberlites from the Eastern Dharwar craton. Anomalously elevated iridium (and other PGE) contents in sediments at the Cretaceous-Paleogene (K-Pg) boundary are commonly attributed either to a large bolide impact triggering the K-Pg mass extinction or to terrestrial causes such as volcanic eruptions (Deccan flood basalts) or even to mantle-plume derived lithospheric gaseous explosions (Verneshots). Lack of unusually high abundances of PGE in the Mainpur orangeties as well as in the co-eval Deccan flood basalts and associated alkaline rocks implies that the anomalous iridium enrichment reported at the K-Pg boundary sections was not sourced from the mantle and likely originated from an extraterrestrial source.

Chalapathi Rao, N. V.; Lehmann, B.; Balaram, V.

2014-04-01

351

Basic moments of phonon density of states spectra and characteristic phonon temperatures of group IV, III-V, and II-VI materials  

NASA Astrophysics Data System (ADS)

We have redigitized a large variety of phonon density of states (PDOS) spectra, that have been published by diferent researchers for group IV (diamond, 3C-SiC, Si, and Ge), III-V (BN, BP, BAs, BSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb), and II-VI materials (ZnO, ZnS, ZnSe, ZnTe, CdS, and CdTe), including calculations of their moments, ??n?, of orders n =-1, 1, 2, and 4. Notwithstanding the obvious differences in concrete shapes of spectra presented for one and the same material by different authors, the respective magnitudes of estimated moments have been found in most cases to be nearly the same (to within uncertainties of some few percent). For most materials under study, the average phonon temperatures of the lower and upper sections of PDOS spectra, ?L and ?U, are found to be by factors of order 0.6 lower or 1.4 higher, respectively, than the average phonon temperature, ?P, of the total PDOS spectra. The estimated high-temperature limits of Debye temperatures, ?D(?), are found to be significantly higher (by factors of order 1.4) than ?P, implying an order-of-magnitude equality, ?D(?)??U (within differences not exceeding an order of ±10%, for all materials under study). The phonon temperatures, ?g, that are effective in controlling the observable temperature dependences of fundamental energy gaps, Eg(T), are found to be usually of the same order as the respective average phonon temperatures, ?g??P. The existing differences between these two qualitatively different types of characteristic phonon temperatures are seen to be limited, for diamond, 3C-SiC, Si, Ge, AlN, GaN, GaP, GaAs, GaSb, InP, InSb, ZnS, ZnSe, ZnTe, and CdTe, to an order of ±12%. We design an exemplary way for precalculating harmonic parts of isochoric heat capacities on the basis of the estimated quadruplets of PDOS spectra moments. This novel calculation scheme is exemplified for silicon and germanium.

Pässler, Roland

2007-05-01

352

The effect of hydrogen as a temporary alloying element on the microstructure and tensile properties of Ti-6Al-4V  

NASA Astrophysics Data System (ADS)

Ti-6Al-4V alloy, to which 0.6 wt pct to 1.0 wt pct (22 to 33 at. pct) hydrogen has been added, can undergo a phase transformation which produces unique, fine microstructures. Specimens of the alloy were heated to 870°C, transformed at temperatures between 540°C and 700°C, and the microstructures were determined as a function of hydrogen content and transformation temperature. Microstructures and tensile properties of sheet specimens were determined after such transformation followed by dehydrogenation at temperatures between 650°C and 760°C. The highest yield strength (1130 MPa) and good ductility (9 pct El) were associated with a fine equiaxed microstructure obtained in material charged with approximately 1.0 wt pct hydrogen, transformed at 565°C and dehydrogenated at 675°C. Lower strengths and ductilities were associated with acicular microstructures produced by transformation at higher temperatures or coarser structures producted at higher dehydrogenation temperatures.

Kerr, William R.

1985-06-01

353

[Removal of gaseous elemental mercury over cerium doped low vanadium loading V2O5-WO3/TiO2 in simulated coal-fired flue gas].  

PubMed

This paper discussed a recent study of mercury removal by gaseous hydrogen chloride over novel Ce doped low vanadium V2O5-WO3/TiO2 catalysts under a bench scale condition. The performances on Hg(0) removal over the catalyst were tested in simulated flue gas with 80-100 microg x m(-3) Hg(0), 8% O2, 10 x10(-6) HCl, 8% H2O, 800 x10(-6) SO2 and balanced with N2. Results showed that about 95% of Hg(0) could be removed. According to the characterization results, BET surface areas had not significant influence on catalytic performance. XPS results indicated that Ce4+ oxide was a mainly form in the catalysts surface, which was beneficial for Hg(0) removal reactions. Water vapor slightly inhibited Hg(0) removal efficiency, due to the competitive adsorption, however, SO2 promoted the oxidation reactions, resulting in higher removal efficiencies. PMID:22165254

Wan, Qi; Duan, Lei; He, Ke-Bin; Chen, Liang; Li, Jun-Hua

2011-09-01

354

Pentaatomic planar tetracoordinate silicon with 14 valence electrons: A large-scale global search of SiXnYmq (n?+?m?=?4; q?=?0, ±1, -2; X, Y?=?main group elements from H to Br).  

PubMed

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, SiXnYmq (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, Li3SiAs2-, HSiY3 (Y?=?Al/Ga), Ca3 SiAl(-) , Mg4 Si(2-) , C2 LiSi, Si3 Y2 (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. © 2014 Wiley Periodicals, Inc. PMID:25430676

Xu, Jing; Ding, Yi-Hong

2015-03-01

355

Discovery of the heaviest elements.  

PubMed

The search for new superheavy elements (SHEs) is at present one of the most exciting adventures in nuclear physics. Thanks to enhanced experimental techniques, the synthesis of elements Z=113 to 118 in reactions using (48)Ca projectiles and targets made of isotopes of the elements neptunium to californium has been claimed. Discovery of the elements Z=114 (named flerovium) and Z=116 (named livermorium) has been accepted by the IUPAC. The others are waiting. The situation for element 113 is particular; here claims on discovery come from groups from RIKEN, Wako, Saitama, Japan and FLNR-JINR, Dubna, Russia. PMID:23335329

Heßberger, Fritz P

2013-02-25

356

Effects of long-lived 10 MeV-scale sterile neutrinos on primordial elemental abundances and the effective neutrino number  

NASA Astrophysics Data System (ADS)

The primordial lithium abundance inferred from spectroscopic observations of metal-poor stars is ˜3 times smaller than the theoretical prediction in the standard big bang nucleosynthesis (BBN) model. We assume a simple model composed of standard model particles and a sterile neutrino ?H with mass of O(10) MeV which decays long after BBN. We then investigate cosmological effects of a sterile neutrino decay, and check if a sterile neutrino can reduce the primordial lithium abundance. We formulate the injection spectrum of nonthermal photon induced by the ?H decay. We take into account the generation of electrons and positrons, e±'s, and active neutrinos at the ?H decay, the primary photon production via the inverse Compton scattering of cosmic background radiation (CBR) by energetic e±, and electromagnetic cascade showers induced by the primary photons. The steady state injection spectrum is then derived as a function of the ?H mass and the photon temperature. The ?H decay produces energetic active neutrinos which are not thermalized, and e±'s which are thermalized. We then derive formulas relevant to the ?H decay rates and formulas for the baryon-to-photon ratio ? and effective neutrino number Neff. The initial abundance, mass, and lifetime of ?H are taken as free parameters. We then consistently solve (1) the cosmic thermal history, (2) nonthermal nucleosynthesis induced by the nonthermal photons, (3) the ? value, and (4) the Neff value. We find that an effective Be7 destruction can occur only if the sterile neutrino decays at photon temperature T =O(1) keV. Amounts of energy injection at the ?H decay are constrained from limits on primordial D and Li7 abundances, the Neff value, and the CBR energy spectrum. We find that Be7 is photodisintegrated and the Li problem is partially solved for the lifetime 104-105 s and the mass ?14 MeV. Be7 destruction by more than a factor of 3 is not possible because of an associated D overdestruction. In the parameter region, the ? value is decreased slightly, while the Neff value is increased by a factor of ?Neff?1. In this study, errors in photodisintegration cross sections of Be7(? ,?)He3 and Li7(? ,?)H3 that have propagated through the literature are corrected, and new functions are derived based on recent nuclear experiments. It is found that the new photodisintegration rates are 2.3 to 2.5 times smaller than the old rates. The correct cross sections thus indicate significantly smaller efficiencies of Be7 and Li7 photodisintegration. Abundances of sterile neutrino necessary for the Li7 reduction are much smaller than thermal freeze-out abundances. The relic sterile neutrino, therefore, must be diluted between the freeze-out and BBN epochs by some mechanism.

Ishida, Hiroyuki; Kusakabe, Motohiko; Okada, Hiroshi

2014-10-01

357

Determination of Specific Forces and Tool Deflections in Micro-milling of Ti-6Al-4V alloy using Finite Element Simulations and Analysis  

NASA Astrophysics Data System (ADS)

Titanium alloys offer superb properties in strength, corrosion resistance and biocompatibility and are commonly utilized in medical devices and implants. Micro-end milling process is a direct and rapid fabrication method for manufacturing medical devices and implants in titanium alloys. Process performance and quality depend upon an understanding of the relationship between cutting parameters and forces and resultant tool deflections to avoid tool breakage. For this purpose, FE simulations of chip formation during micro-end milling of Ti-6Al-4V alloy with an ultra-fine grain solid carbide two-flute micro-end mill are investigated using DEFORM software. At first, specific forces in tangential and radial directions of cutting during micro-end milling for varying feed advance and rotational speeds have been determined using designed FE simulations for chip formation process. Later, these forces are applied to the micro-end mill geometry along the axial depth of cut in 3D analysis of ABAQUS. Consequently, 3D distributions for tool deflections & von Misses stress are determined. These analyses will yield in establishing integrated multi-physics process models for high performance micro-end milling and a leap-forward to process improvements.

Farina, Simone; Thepsonti, Thanongsak; Ceretti, Elisabetta; Özel, Tugrul

2011-05-01

358

Determination of Specific Forces and Tool Deflections in Micro-milling of Ti-6Al-4V alloy using Finite Element Simulations and Analysis  

SciTech Connect

Titanium alloys offer superb properties in strength, corrosion resistance and biocompatibility and are commonly utilized in medical devices and implants. Micro-end milling process is a direct and rapid fabrication method for manufacturing medical devices and implants in titanium alloys. Process performance and quality depend upon an understanding of the relationship between cutting parameters and forces and resultant tool deflections to avoid tool breakage. For this purpose, FE simulations of chip formation during micro-end milling of Ti-6Al-4V alloy with an ultra-fine grain solid carbide two-flute micro-end mill are investigated using DEFORM software.At first, specific forces in tangential and radial directions of cutting during micro-end milling for varying feed advance and rotational speeds have been determined using designed FE simulations for chip formation process. Later, these forces are applied to the micro-end mill geometry along the axial depth of cut in 3D analysis of ABAQUS. Consequently, 3D distributions for tool deflections and von Misses stress are determined. These analyses will yield in establishing integrated multi-physics process models for high performance micro-end milling and a leap-forward to process improvements.

Farina, Simone; Ceretti, Elisabetta [University of Brescia, Department of Mechanical and Industrial Engineering (Italy); Thepsonti, Thanongsak; Oezel, Tugrul [Rutgers University, Department of Industrial and System Engineering, New Jersey (United States)

2011-05-04

359

Chemical characterization of element 112.  

PubMed

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

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

360

Superheavy Elements  

ERIC Educational Resources Information Center

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)

Tsang, Chin Fu

1975-01-01

361

Elemental Education.  

ERIC Educational Resources Information Center

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)

Daniel, Esther Gnanamalar Sarojini; Saat, Rohaida Mohd.

2001-01-01

362

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.

363

Finite element meshing of three-dimensional faulted domains Peter van Thienen and Thomas Geenen. Faculty of Geosciences, Mantle dynamics group, Utrecht University, The Netherlands. thienen@geo.uu.nl, geenen@geo.uu.nl  

E-print Network

Finite element meshing of three-dimensional faulted domains Peter van Thienen and Thomas Geenen@geo.uu.nl, geenen@geo.uu.nl Abstract Meshing of 3-D spaces for finite element applications is often a complicated to facilitate the step from geodynamical maps to finite element meshes (box 1). The second is a mesh generator

van Thienen, Peter

364

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

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.

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

365

Travel-related MERS-CoV cases: an assessment of exposures and risk factors in a group of Dutch travellers returning from the Kingdom of Saudi Arabia, May 2014  

PubMed Central

Background In May 2014, Middle East respiratory syndrome coronavirus (MERS-CoV) infection, with closely related viral genomes, was diagnosed in two Dutch residents, returning from a pilgrimage to Medina and Mecca, Kingdom of Saudi Arabia (KSA). These patients travelled with a group of 29 other Dutch travellers. We conducted an epidemiological assessment of the travel group to identify likely source(s) of infection and presence of potential risk factors. Methods All travellers, including the two cases, completed a questionnaire focussing on potential human, animal and food exposures to MERS-CoV. The questionnaire was modified from the WHO MERS-CoV questionnaire, taking into account the specific route and activities of the travel group. Results Twelve non-cases drank unpasteurized camel milk and had contact with camels. Most travellers, including one of the two patients (Case 1), visited local markets, where six of them consumed fruits. Two travellers, including Case 1, were exposed to coughing patients when visiting a hospital in Medina. Four travellers, including Case 1, visited two hospitals in Mecca. All travellers had been in contact with Case 1 while he was sick, with initially non-respiratory complaints. The cases were found to be older than the other travellers and both had co-morbidities. Conclusions This epidemiological study revealed the complexity of MERS-CoV outbreak investigations with multiple potential exposures to MERS-CoV reported such as healthcare visits, camel exposure, and exposure to untreated food products. Exposure to MERS-CoV during a hospital visit is considered a likely source of infection for Case 1 but not for Case 2. For Case 2, the most likely source could not be determined. Exposure to MERS-CoV via direct contact with animals or dairy products seems unlikely for the two Dutch cases. Furthermore, exposure to a common but still unidentified source cannot be ruled out. More comprehensive research into sources of infection in the Arabian Peninsula is needed to strengthen and specify the prevention of MERS-CoV infections. PMID:25328533

2014-01-01

366

Crystal Structure of Cesium-V  

NASA Astrophysics Data System (ADS)

The crystal structure of the high-pressure phase cesium-V was investigated using monochromatic synchrotron x-ray diffraction. Full profile refinements of powder diffraction data resulted in a solution with space group Cmca and 16 atoms in the orthorhombic unit cell. The Cs-V structure can be viewed as a distorted fcc structure. Atoms occupy two different Wyckoff positions with 10-fold and 11-fold coordination, respectively. This new structure type is considered a possible candidate for high-pressure phases of other elemental metals.

Schwarz, U.; Takemura, K.; Hanfland, M.; Syassen, K.

1998-09-01

367

III-V aresenide-nitride semiconductor materials and devices  

NASA Technical Reports Server (NTRS)

III-V arsenide-nitride semiconductor crystals, methods for producing such crystals and devices employing such crystals. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

1997-01-01

368

Six Essential Elements- National Geographic Photograph Activity  

NSDL National Science Digital Library

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.

Patricia Steed

2012-08-01

369

Orbital Elements  

NSDL National Science Digital Library

Coordinates for tracking the International Space Station and the Mir Space Station are available here from NASA's Johnson Space Center Flight Design and Dynamics Division. The Orbital Elements page offers real-time data for use in ground track plotting programs. The site cautions the data are for ground track plotting programs only and "should not be used for precise applications or analysis!"

370

Element Report  

NSDL National Science Digital Library

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 ...

Petersen, Mrs.

2014-04-07

371

Element Research.  

ERIC Educational Resources Information Center

Describes a research assignment for 8th grade students on the elements of the periodic table. Students use web-based resources and a chemistry handbook to gather information, construct concept maps, and present the findings to the full class using the mode of their choice: a humorous story, a slideshow or gameboard, a brochure, a song, or skit.…

Herald, Christine

2001-01-01

372

The effects of group IV B/V B/VI B additions on the magnetic properties of Sm2 + delta Fe17 carbonitrides  

NASA Astrophysics Data System (ADS)

Curie temperature, anisotropy field, and lattice constants are measured for the Sm2+? Fe17M0.4 (??0.6) carbonitrides for M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W. It is found that minor additions of M reduce the Curie temperature, with the largest decrease of 28 K for M=Mo, and that the fluctuations in Curie temperature are not related to the changes in unit cell volumes. Compared with Sm2+? Fe17NxCy, most of the M additives reduce the anisotropy field with the largest decrease of about 10 kOe for M=Zr. The V addition has almost no effect on the anisotropy field and the Ti addition gives a 4-5 kOe enhancement of the anisotropy field.

Chen, X.; Girt, Er.; Altounian, Z.

1994-05-01

373

Simple groups stabilizing polynomials  

E-print Network

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 $G < H \\le SL(V)$ such that $V/H$ has the same dimension as $V/G$. The main results of this paper are new even in the special case where $k$ is the complex numbers.

Skip Garibaldi; Robert Guralnick

2014-08-22

374

Trading group theory for randomness  

Microsoft Academic Search

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

László Babai

1985-01-01

375

Correlation of trace elements in hair with colon cancer  

SciTech Connect

The trace element content of 116 hair samples from patients with colon cancer and from referent series of patients who had a variety of other diseases were measured using proton-induced x-ray emission (PIXE). The patients had been on largely uncontrolled diets, and the interest was whether there were differences in trace element concentrations attributable to the effects of colon cancer. The concentrations of K, Ca, Mn, Fe, Cu, Zn, Se, Br, and Rb were determined using a beam of 2.5-MeV protons. Minimum detectable limits (MDL) of 0.3 ppM were obtained for Zn and Se. Cluster analysis of the data set did not reveal any significant differences between the cancer and control groups. Mean values and ranges obtained for the elemental concentrations show good agreement with other published determinations. 20 refs., 3 figs., 3 tabs.

Kwiatek, W.M.; Cholewa, M.; Kajfosz, J.; Jones, K.W.; Shore, R.E.; Redrick, A.L.

1986-01-01

376

Glueball matrix elements: a lattice calculation and applications  

E-print Network

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/psi 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 f_0 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.

Harvey B. Meyer

2008-08-22

377

NDR SPICE and QSPICE: Augmented SPICE Simulator Developed by Mazumder's Research Group for RTD and other quantum devices having folded-back I-V.  

E-print Network

NDR SPICE and QSPICE: Augmented SPICE Simulator Developed by Mazumder's Research Group for RTD SPICE (1994) and was added with simple mechanisms like forced convergence routine to recover from to overcome the limitations of source stepping and Gmin stepping that are used in commercial SPICE simulators

Mazumder, Pinaki

378

Three-year results comparing platinum-chromium PROMUS element and cobalt-chromium XIENCE V everolimus-eluting stents in de novo coronary artery narrowing (from the PLATINUM Trial).  

PubMed

In the randomized PLATINUM trial, the PROMUS Element platinum-chromium everolimus-eluting stent (PtCr-EES; Boston Scientific, Natick, Massachusetts) was noninferior to the XIENCE V cobalt-chromium everolimus-eluting stent (CoCr-EES; Boston Scientific and Abbott Vascular, Santa Clara, California) for the primary end point of 1-year target lesion failure. This study reports the 3-year outcomes. Patients (n=1,530) with 1 or 2 de novo native coronary artery lesions (baseline vessel diameter?2.50 mm to ?4.25 mm and length?24 mm) were randomized 1:1 to PtCr-EES versus CoCr-EES. Three-year follow-up was available in 93.9% (703 of 749) of patients with CoCr-EES and 96.7% (733 of 758) of patients with PtCr-EES. Comparing CoCr-EES with PtCr-EES, 3-year rates of death (4.3% vs 3.7%, hazard ratio [HR] 0.88, 95% confidence interval [CI] 0.52 to 1.48, p=0.62), cardiac death (1.9% vs 1.2%, HR 0.63, 95% CI 0.27 to 1.45, p=0.27), myocardial infarction (2.5% vs 2.3%, HR 0.92, 95% CI 0.48 to 1.79, p=0.81), ischemia-driven target lesion revascularization (4.9% vs 3.5%, HR 0.72, 95% CI 0.43 to 1.20, p=0.21), and Academic Research Consortium definite or probable stent thrombosis (0.5% vs 0.7%, HR 1.23, 95% CI 0.33 to 4.57, p=0.76) were not significantly different. In conclusion, 3-year results of the PLATINUM randomized, controlled, clinical trial demonstrate comparable safety and efficacy outcomes of the PROMUS Element PtCr-EES and the XIENCE V CoCr-EES. PMID:24530167

Meredith, Ian T; Teirstein, Paul S; Bouchard, Alain; Carrié, Didier; Möllmann, Helge; Oldroyd, Keith G; Hall, Jack; Allocco, Dominic J; Dawkins, Keith D; Stone, Gregg W

2014-04-01

379

Hypermutation is observed only in antibody H chain V region transgenes that have recombined with endogenous immunoglobulin H DNA: implications for the location of cis-acting elements required for somatic mutation.  

PubMed

Mice with transgenes containing an antibody H chain V region (VHDJH) gene were used in an analysis of the cis-acting elements required for hypermutation of immunoglobulin (Ig) V genes. These transgenes can somatically recombine with endogenous IgH DNA, leading to the formation of functional heavy (H) chains partially encoded by the transgenic VHDJH. The transgenomes in the five different lines of mice analyzed contain as little as 150 bp, and as much as 2.8 kb of natural DNA flanking the 5' side of the VH and either 1.5 or 2.3 kb (including the intronic enhancer and 5' matrix attachment region [MAR]) flanking the 3' side of VH. Hybridomas were constructed from immunized transgenic mice, and transgenes present in these hybridomas that had or had not recombined to form functional H chain loci were sequenced. The data obtained show that: (a) the recombined transgenes contain hypermutated VH genes; and (b) among such transgenes, even those containing only 150 bp of natural VH 5' flanking sequence and several kilobases of 5' plasmid vector sequence display a frequency, distribution, and type of mutation characteristic of conventional IgH loci. The data also indicate that transgenic VHDJH genes that have not recombined with endogenous IgH DNA are not substrates for hypermutation, even if they are flanked by 2.8 kb of natural 5' DNA, and 2.3 kb of natural 3' DNA, including the JH2-JH4 region, a MAR, and the intronic enhancer. Collectively, the data suggest that sequences 5' of the VH promoter are dispensable, a VH promoter and the intronic IgH enhancer region are not sufficient, and a region(s) within or 3' of the IgH constant region locus is requisite, for hypermutation of Ig VH transgenes. PMID:8436910

Giusti, A M; Manser, T

1993-03-01

380

Hypermutation is observed only in antibody H chain V region transgenes that have recombined with endogenous immunoglobulin H DNA: implications for the location of cis-acting elements required for somatic mutation  

PubMed Central

Mice with transgenes containing an antibody H chain V region (VHDJH) gene were used in an analysis of the cis-acting elements required for hypermutation of immunoglobulin (Ig) V genes. These transgenes can somatically recombine with endogenous IgH DNA, leading to the formation of functional heavy (H) chains partially encoded by the transgenic VHDJH. The transgenomes in the five different lines of mice analyzed contain as little as 150 bp, and as much as 2.8 kb of natural DNA flanking the 5' side of the VH and either 1.5 or 2.3 kb (including the intronic enhancer and 5' matrix attachment region [MAR]) flanking the 3' side of VH. Hybridomas were constructed from immunized transgenic mice, and transgenes present in these hybridomas that had or had not recombined to form functional H chain loci were sequenced. The data obtained show that: (a) the recombined transgenes contain hypermutated VH genes; and (b) among such transgenes, even those containing only 150 bp of natural VH 5' flanking sequence and several kilobases of 5' plasmid vector sequence display a frequency, distribution, and type of mutation characteristic of conventional IgH loci. The data also indicate that transgenic VHDJH genes that have not recombined with endogenous IgH DNA are not substrates for hypermutation, even if they are flanked by 2.8 kb of natural 5' DNA, and 2.3 kb of natural 3' DNA, including the JH2-JH4 region, a MAR, and the intronic enhancer. Collectively, the data suggest that sequences 5' of the VH promoter are dispensable, a VH promoter and the intronic IgH enhancer region are not sufficient, and a region(s) within or 3' of the IgH constant region locus is requisite, for hypermutation of Ig VH transgenes. PMID:8436910

1993-01-01

381

Solid-state ‘‘magic-angle’’ sample-spinning nuclear magnetic resonance spectroscopic study of group III–V (13–15) semiconductors  

Microsoft Academic Search

We have obtained 27 Al, 69 Ga, 71 Ga, 113 In, and 115 In static and ‘‘magic-angle’’ sample-spinning (MASS) solid-state nuclear magnetic resonance (NMR) spectra of a series of polycrystalline III–V semiconductors (AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb) at magnetic field strengths of 8.45 and 11.7 T. Line-broadening mechanisms have been identified by

Oc Hee Han; Hye Kyung C. Timken; Eric Oldfield

1988-01-01

382

The Tuberin (TSC2), Autosomal Dominant Polycystic Kidney Disease (PKD1), and Somatostatin Type V Receptor (SSTR5) Genes Form a Synteny Group in the FuguGenome  

Microsoft Academic Search

The tuberous sclerosis 2 (TSC2) and polycystic kidney disease 1 (PKD1) genes are adjacent on human chromosome 16p13.3 and form part of a conserved synteny group with mouse chromosome 17. We have determined that the PKD1 gene is evolutionarily conserved, single copy, and linked to TSC2 in theFugugenome. A short cosmid contig has been identified containing both genes based on

Richard Sandford; Barbara Sgotto; Timothy Burn; Sydney Brenner

1996-01-01

383

The Zurich Environmental Study (ZENS) of Galaxies in Groups along the Cosmic Web. V. Properties and Frequency of Merging Satellites and Centrals in Different Environments  

NASA Astrophysics Data System (ADS)

We use the Zurich Environmental Study database to investigate the environmental dependence of the merger fraction ? and merging galaxy properties in a sample of ~1300 group galaxies with M > 109.2 M ? and 0.05 < z < 0.0585. In all galaxy mass bins investigated in our study, we find that ? decreases by a factor of ~2-3 in groups with halo masses M HALO > 1013.5 M ? relative to less massive systems, indicating a suppression of merger activity in large potential wells. In the fiducial case of relaxed groups only, we measure a variation of ??/?log (M HALO) ~ –0.07 dex–1, which is almost independent of galaxy mass and merger stage. At galaxy masses >1010.2 M ?, most mergers are dry accretions of quenched satellites onto quenched centrals, leading to a strong increase of ? with decreasing group-centric distance at these mass scales. Both satellite and central galaxies in these high-mass mergers do not differ in color and structural properties from a control sample of nonmerging galaxies of equal mass and rank. At galaxy masses of <1010.2 M ? where we mostly probe satellite-satellite pairs and mergers between star-forming systems close pairs (projected distance <10-20 kpc) show instead ~2 × enhanced (specific) star formation rates and ~1.5 × larger sizes than similar mass, nonmerging satellites. The increase in both size and star formation rate leads to similar surface star formation densities in the merging and control-sample satellite populations. Based on observations collected at the European Southern Observatory, La Silla Chile. Program ID 177.A-0680.

Pipino, A.; Cibinel, A.; Tacchella, S.; Carollo, C. M.; Lilly, S. J.; Miniati, F.; Silverman, J. D.; van Gorkom, J. H.; Finoguenov, A.

2014-12-01

384

New results on mass measurements of stored neutron-rich nuclides in the element range from Pt to U with the FRS-ESR facility at 360-400 MeV/u  

NASA Astrophysics Data System (ADS)

Masses of 238U projectile fragments have been measured with time-resolved Schottky Mass Spectrometry (SMS) at the FRS-ESR facility at GSI. The exotic nuclei were created in the production target at the entrance of the fragment separator FRS, spatially separated in flight and injected into the storage-cooler ring ESR at about 70% light velocity. This means the ions were mainly bare or carried only a few electrons, e.g., the population of Li-like ions was below 1% for Pt fragments. Accurate new mass values of 33 neutron-rich, stored exotic nuclei in the element range from platinum to uranium have been obtained for the first time. In total more than 150 nuclides including references with well-known masses have been covered in this large-area SMS measurement. A novel data analysis has been applied which reduces the systematic errors by taking into account the velocity profile of the cooler electrons and the residual ion-optical dispersion in this part of the storage ring. The experiment, the data analysis, and the mass values are presented. The experimental data are compared with theoretical predictions demonstrating systematic deviations of up to 1500 keV from modern mass models.

Chen, L.; Plaß, W. R.; Geissel, H.; Knöbel, R.; Kozhuharov, C.; Litvinov, Yu. A.; Patyk, Z.; Scheidenberger, C.; Siegie?-Iwaniuk, K.; Sun, B.; Weick, H.; Beckert, K.; Beller, P.; Bosch, F.; Boutin, D.; Caceres, L.; Carroll, J. J.; Cullen, D. M.; Cullen, I. J.; Franzke, B.; Gerl, J.; Górska, M.; Jones, G. A.; Kishada, A.; Kurcewicz, J.; Litvinov, S. A.; Liu, Z.; Mandal, S.; Montes, F.; Münzenberg, G.; Nolden, F.; Ohtsubo, T.; Podolyák, Zs.; Propri, R.; Rigby, S.; Saito, N.; Saito, T.; Shindo, M.; Steck, M.; Walker, P. M.; Williams, S.; Winkler, M.; Wollersheim, H.-J.; Yamaguchi, T.

2012-05-01

385

Trends in Ionization Energy of Transition-Metal Elements  

ERIC Educational Resources Information Center

A rationale for the difference in the periodic trends in the ionization energy of the transition-metal elements versus the main-group elements is presented. The difference is that in the transition-metal elements, the electrons enter an inner-shell electron orbital, while in the main-group elements, the electrons enter an outer-shell electron…

Matsumoto, Paul S.

2005-01-01

386

VOLUME 88, NUMBER 4 P H Y S I C A L R E V I E W L E T T E R S 28 JANUARY 2002 Spin Wave Wells in Nonellipsoidal Micrometer Size Magnetic Elements  

E-print Network

in Nonellipsoidal Micrometer Size Magnetic Elements J. Jorzick, S. O. Demokritov,* and B. Hillebrands Fachbereich, micrometer size magnetic thin film elements the dynamic magnetic eigenexcitations (spin waves) may exhibit in the highly inhomogeneous internal magnetic field within the element. DOI: 10.1103/PhysRevLett.88.047204 PACS

Demokritov, S.O.

387

Alkali metal and rare earth element evolution of rock-forming minerals from the Gatumba area pegmatites (Rwanda): Quantitative assessment of crystal-melt fractionation in the regional zonation of pegmatite groups  

NASA Astrophysics Data System (ADS)

This study presents a general model for the evaluation of Rayleigh fractional crystallisation as the principal differentiation mechanism in the formation of regionally zoned common and rare-element pegmatites. The magmatic evolution of these systems from a granitic source is reconstructed by means of alkali element and rare earth element (REE) analyses of rock-forming minerals (feldspars, micas and tourmaline), which represent a whole sequence of regional pegmatite zonation. The Gatumba pegmatite field (Rwanda, Central Africa) is chosen as case study area because of its well-developed regional zonation sequence. The pegmatites are spatially and temporally related to peraluminous G4-granites (986 ± 10 Ma). The regional zonation is developed around a G4-granite and the proximal pegmatites grade outwardly into biotite, two-mica and muscovite pegmatites. Rare-element (Nb-Ta-Sn) pegmatites occur most distal from the granite.

Hulsbosch, Niels; Hertogen, Jan; Dewaele, Stijn; André, Luc; Muchez, Philippe

2014-05-01

388

LABORATORY V ELECTRIC CIRCUITS  

E-print Network

Lab V -1 LABORATORY V ELECTRIC CIRCUITS Electrical devices are the cornerstones of our modern world in applying the principles of conservation to the very useful realm of electric circuits. OBJECTIVES: After the behavior of the energy output of any element in a circuit; · use the concept of electrical potential

Minnesota, University of

389

BANYAN. V. A Systematic All-sky Survey for New Very Late-type Low-mass Stars and Brown Dwarfs in Nearby Young Moving Groups  

NASA Astrophysics Data System (ADS)

We present the BANYAN All-Sky Survey (BASS) catalog, consisting of 228 new late-type (M4-L6) candidate members of nearby young moving groups (YMGs) with an expected false-positive rate of ~13%. This sample includes 79 new candidate young brown dwarfs and 22 planetary-mass objects. These candidates were identified through the first systematic all-sky survey for late-type low-mass stars and brown dwarfs in YMGs. We cross-matched the Two Micron All Sky Survey and AllWISE catalogs outside of the galactic plane to build a sample of 98,970 potential >=M5 dwarfs in the solar neighborhood and calculated their proper motions with typical precisions of 5-15 mas yr–1. We selected highly probable candidate members of several YMGs from this sample using the Bayesian Analysis for Nearby Young AssociatioNs II tool (BANYAN II). We used the most probable statistical distances inferred from BANYAN II to estimate the spectral type and mass of these candidate YMG members. We used this unique sample to show tentative signs of mass segregation in the AB Doradus moving group and the Tucana-Horologium and Columba associations. The BASS sample has already been successful in identifying several new young brown dwarfs in earlier publications, and will be of great interest in studying the initial mass function of YMGs and for the search of exoplanets by direct imaging; the input sample of potential close-by >=M5 dwarfs will be useful to study the kinematics of low-mass stars and brown dwarfs and search for new proper motion pairs.

Gagné, Jonathan; Lafrenière, David; Doyon, René; Malo, Lison; Artigau, Étienne

2015-01-01

390

Course Announcement: Spring 2014 Finite Element Methods for Engineers  

E-print Network

Course Announcement: Spring 2014 Finite Element Methods for Engineers CEEN 506 3 Hours Credit Time.v.griffiths@mines.edu Web: www.mines.edu/~vgriffit This course combines finite element theory with practical programming element method", by I.M. Smith, D.V. Griffiths and L. Margetts, John Wiley and Sons, 5th ed., 2014

391

Finite reflection groups q, t-Fu-Catalan numbers for real reflection groups  

E-print Network

, 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

Faridi, Sara

392

Transpositionally active episomal hAT elements  

PubMed Central

Background hAT elements and V(D)J recombination may have evolved from a common ancestral transposable element system. Extrachromosomal, circular forms of transposable elements (referred to here as episomal forms) have been reported yet their biological significance remains unknown. V(D)J signal joints, which resemble episomal transposable elements, have been considered non-recombinogenic products of V(D)J recombination and a safe way to dispose of excised chromosomal sequences. V(D)J signal joints can, however, participate in recombination reactions and the purpose of this study was to determine if hobo and Hermes episomal elements are also recombinogenic. Results Up to 50% of hobo/Hermes episomes contained two intact, inverted-terminal repeats and 86% of these contained from 1-1000 bp of intercalary DNA. Episomal hobo/Hermes elements were recovered from Musca domestica (a natural host of Hermes), Drosophila melanogaster (a natural host of hobo) and transgenic Drosophila melanogaster and Aedes aegypti (with autonomous Hermes elements). Episomal Hermes elements were recovered from unfertilized eggs of M. domestica and D. melanogaster demonstrating their potential for extrachromosomal, maternal transmission. Reintegration of episomal Hermes elements was observed in vitro and in vivo and the presence of Hermes episomes resulted in lower rates of canonical Hermes transposition in vivo. Conclusion Episomal hobo/Hermes elements are common products of element excision and can be maternally transmitted. Episomal forms of Hermes are capable of integration and also of influencing the transposition of canonical elements suggesting biological roles for these extrachromosomal elements in element transmission and regulation. PMID:20003420

2009-01-01

393

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

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

Scibior, Agnieszka; Adamczyk, Agnieszka; Go??biowska, Dorota; Nied?wiecka, Irmina; Fornal, Emilia

2014-04-01

394

BANYAN. V. A Systematic All-Sky Survey for New Very Late-Type Low-Mass Stars and Brown Dwarfs in Nearby Young Moving Groups  

E-print Network

We present the BANYAN All-Sky Survey (BASS) catalog, consisting of 228 new late-type (M4-L6) candidate members of nearby young moving groups (YMGs) with an expected false-positive rate of ~ 13%. This sample includes 79 new candidate young brown dwarfs and 22 planetary-mass objects. These candidates were identified through the first systematic all-sky survey for late-type low-mass stars and brown dwarfs in YMGs. We cross-matched the 2MASS and ALLWISE catalogs outside of the galactic plane to build a sample of 98 970 potential $\\geq$ M5 dwarfs in the solar neighborhood and calculated their proper motions with typical precisions of 5-15 mas yr$^{-1}$. We selected highly probable candidate members of several YMGs from this sample using the Bayesian Analysis for Nearby Young AssociatioNs II tool (BANYAN II). We used the most probable statistical distances inferred from BANYAN II to estimate the spectral type and mass of these candidate YMG members. We used this unique sample to show tentative signs of mass segrega...

Gagné, Jonathan; Doyon, René; Malo, Lison; Artigau, Étienne

2014-01-01

395

Elasticity of the superconducting metals V, Nb, Ta, Mo, and W at high pressure L. Koci,1 Y. Ma,2,3 A. R. Oganov,2,4 P. Souvatzis,1 and R. Ahuja1,5  

E-print Network

of this type of phase in other elements in the Periodic Table both from experiments and theory. Moreover, very and Ta in the Periodic Table, are often used as pressure cali- brant materials at high pressure and. Furthermore, the c11, c12, and c44 constants for the group-V elements showed erratic behaviors whereas

Oganov, Artem R.

396

Group Theory: It's a SNAP.  

ERIC Educational Resources Information Center

Introduces concepts of modern algebraic group theory in the form of a game. Peg boards and rubber bands represent nonnumerical group elements and are manipulated under the operation of reorienting a regular polygon. Symmetry groups are used to explore set properties, as well as commutative and noncommutative operations. (CMS)

Huetinck, Linda

1996-01-01

397

An optical region elemental abundance analysis of the chemically peculiar HgMn star chi LUPI  

NASA Astrophysics Data System (ADS)

The optical spectrum of the chemically peculiar HgMn type binary star chi Lupi has been analyzed to determine atmospheric parameters and elemental abundances. Echelle spectra were obtained with the 3.9 m Anglo-Australian telescope to exploit the extreme shape-lined nature of the spectrum. This study was undertaken in support of ultraviolet analyses currently underway that utilize echell spectra obtained with the Hubble Space Telescope. For the B9.5 V primary star we obtain Teff = 10650 K, log g = 3.9, and xi = 0 km/s, while for the A2 V secondary, Teff = 9200 K, log g = 4.0, and xi = 2 km/s. Most of the elemental abundances are typical of HgMn stars with similar Teff showing an overall iron-peak elemental abundance distribution that is basically solar in nature with enhancement of the light elements Si, P, and S, as well as all detected elements heavier than the iron group. Abundances for several elements have been determined for the first time in this star, including several of the rare-earths. The secondary star spectrum shows Am star characteristics. We also discuss the relative merits of the equivalent width and synthetic spectrum techniques in determining the elemental abundances, concluding that the synthetic spectrum technique is necessary for obtaining abundances with the utmost accuracy.

Wahlgren, Glenn M.; Adelman, Saul J.; Robinson, Richard D.

1994-10-01

398

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.

399

I. Novel methods to gallium nitride heterostructures via UHV-CVD and azidogallanes. II. Synthesis of related group IV and V covalent systems  

NASA Astrophysics Data System (ADS)

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 temperatures. The family of azidogallanes of the formula HnX2-nGaN 3 (X = Cl, Br; n = 1-2) have been prepared and identified by spectroscopic methods. C12GaN3 has been used to deposit heteroeptaxial GaN on sapphire at 700°C and high quality wurtzite material on Si. This is the first example of an entirely inorganic single-source precursor used to produce nitride material at 500--700°C with growth rates of 5--40nm/min. [HCIGaN3]4, the first example of a group 13 metal cyclooctane-like structure with bridging azide ligands, has been prepared. Film growth at 500--700°C producing columnar wurtzite GaN and room temperature decomposition to yield mixed-phase (wurtzite/zinc blende) nanocrystalline GaN fibrous material is demonstrated. (D2)H2GaN3 is prepared in high yield and purity by the reduction of Br2GaN3 with LiGaH 4. This molecule affords the simplest chemical route to GaN material decomposing via elimination of H2 and N2 to yield stoichiometric GaN material at uncommonly low temperatures of 200--800°C. This compound and its deuterium analog is readily distilled at reduced pressure (0.20 Torr, 40°C), and is remarkably stable under vacuum or inert atmosphere for extended periods (weeks). Germylene insertion chemistry has been used to produce the compound (GeBr3)3CH by complete insertion reaction of HCBr 3 (bromoform) and GeBr2.dioxane at 85% yield. The molecule is identified by chemical analysis, spectroscopic properties and mass spectrum. The corresponding hydrde (GeH3)3CH, is prepared by reduction of the bromide with LiAIH4 in 15--20% yield, and is identified with spectroscopic analysis and gas phase electron diffraction. A gas phase electron diffraction analysis is also presented for the related (GeH3)4C. Reactions of SiH4 with (SiH2CI)4C at 625--740°C produce Si-C alloys of composition Si1-yCy with carbon concentrations from 5--20%. Infrared analysis, Rutherford backscattering, and electron microscopy, confirm the composition and reveal a lack of the stable beta-SiC phase. Reactions of (SiH2Cl)4C with excess ammonia produce novel Si-C-N films of composition Si4CN4 at temperatures from 625--750°C. Rutherford backscattering confirms the stoichiometry of the material and reveals a lack of Cl and, 0 impurities. Microindentation experiments of the Si--C and Si--C--N films yield hardness slightly greater than pure Si for Si--C, and intermediate to Si3N4 and SiC for Si--C--N respectively.

McMurran, Jeffrey Allen

1998-12-01

400

Trace element abundances in andesites  

Microsoft Academic Search

Abundance data for Cs, Rb, Tl, Ba, Pb, Sr, the rare earths, Th, U, Zr, Hf, Sn, Nb, Mo, Mn, Cu, Co, Ni, Sc, V, Cr, Ag, Sb and the major elements are reported for two andesites and a dacite from Saipan, nine andesites and a dacite from Bougainville and two andesites from Fiji. The Saipan rocks are low-K varieties

S. R. Taylor; Annette C. Capp; A. L. Graham; D. H. Blake

1969-01-01

401

Phytoremediation of Soil Trace Elements  

Technology Transfer Automated Retrieval System (TEKTRAN)

This chapter summarizes research progress in development of phytoremediation technologies. Some soils have become contaminated by trace elements enough to kill plants, inhibit soil organisms, and/or threaten wildlife, humans or the environment. Traditional remediation by dig and haul methods are v...

402

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.

2007-11-08

403

On perfect order subsets in finite groups  

Microsoft Academic Search

If $G$ is a finite group and $x\\\\in G$ then the set of all elements of $G$ having the same order as $x$ is called {\\\\em an order subset of $G$ determined by $x$} (see [2]). We say that $G$ is a {\\\\em group with perfect order subsets} or briefly, $G$ is a {\\\\em $POS$-group} if the number of elements

Nguyen Trong Tuan; Bui Xuan Hai

2010-01-01

404

Intermediate Element Abundances In Galaxy Clusters  

NASA Technical Reports Server (NTRS)

We present the average abundances of the intermediate elements obtained by performing a stacked analysis of all the galaxy clusters in the archive of the X-ray telescope AKA. We determine the abundances of Fe, Si, S, and Ni as a function of cluster temperature (mass) from 1 - 10 keV, and place strong upper limits on the abundances of Ca and Ar. In general, Si and Ni are overabundant with respect to Fe, while Ar and Ca are very underabundant. The discrepancy between the abundances of Si, S , Ar, and Ca indicate that the alpha-elements do not behave homogeneously as a single group. We show that the abundances of the most well-determined elements Fe, Si, and S in conjunction with recent theoretical supernovae yields do not give a consistent solution for the fraction of material produced by Type Ia and Type II supernovae at any temperature or mass. The general trend is for higher temperature clusters to have more of their metals produced in Type II supernovae than in Type Ias. The inconsistency of our results with abundances in the Milky Way indicate that spiral galaxies are not the dominant metal contributors to the intracluster medium (ICM). The pattern of elemental abundances requires an additional source of metals beyond standard SNIa and SNII enrichment. The properties of this new source are well matched to those of Type II supernovae with very massive, metal-poor progenitor stars. These results are consistent with a significant fraction of the ICM metals produced by an early generation of population III stars.

White, Nicholas E. (Technical Monitor); Baumgartner, W. H.; Loewenstein, M.; Horner, D. L.; Mushotzky, R. F.

2003-01-01

405

Isomeric forms of divalent heavier group 14 element hydrides: characterization of Ar'(H)GeGe(H)Ar' and Ar'(H)(2)GeGeAr'.PMe(3) (Ar' = C(6)H(3)-2,6-Dipp(2); Dipp = C(6)H(3)-2,6-Pr(i)(2)).  

PubMed

The reduction of Ar'GeCl (Ar' = C6H3-2,6-Dipp2; Dipp = C6H3-2,6-Pri2) with LiBH(Bus)3 affords the first heavier group 14 element dimetallene hydride Ar'(H)GeGe(H)Ar' which, upon further reaction with PMe3, yields the base-stabilized isomeric form Ar'(H)2GeGeAr'.PMe3. PMID:12630862

Richards, Anne F; Phillips, Andrew D; Olmstead, Marilyn M; Power, Philip P

2003-03-19

406

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

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

Kazuhiko Takahashi; Yohey Terai; Mutsumi Nishida; Norihiro Okada

407

Application of Heisenberg's S matrix program to the angular scattering of the H + D2(v(i) = 0, j(i) = 0) ? HD(v(f) = 3, j(f) = 0) + D reaction: piecewise S matrix elements using linear, quadratic, step-function, and top-hat parametrizations.  

PubMed

A previous paper by Shan and Connor (Phys. Chem. Chem. Phys. 2011, 13, 8392) reported the surprising result that four simple parametrized S matrices can reproduce the forward-angle glory scattering of the H + D(2)(v(i)=0,j(i)=0) ? HD(v(f)=3,j(f)=0) + D reaction, whose differential cross section (DCS) had been computed in a state-of-the-art scattering calculation for a state-of-the-art potential energy surface. Here, v and j are vibrational and rotational quantum numbers, respectively, and the translational energy is 1.81 eV. This paper asks the question: Can we replace the analytic functions (of class C(?)) used by Shan-Connor with simpler mathematical functions and still reproduce the forward-angle glory scattering? We first construct S matrix elements (of class C(0)) using a quadratic phase and a piecewise-continuous pre-exponential factor consisting of three pieces. Two of the pieces are constants, with one taking the value N (a real normalization constant) at small values of the total angular momentum number, J; the other piece has the value 0 at large J. These two pieces are joined at intermediate values of J by either a straight line, giving rise to the linear parametrization (denoted param L), or a quadratic curve, which defines the quadratic parametrization (param Q). We find that both param L and param Q can reproduce the glory scattering for center-of-mass reactive scattering angles, ?(R) ? 30°. Second, we use a piecewise-discontinuous pre-exponential factor and a quadratic phase, giving rise to a step-function parametrization (param SF) and a top-hat parametrization (param TH). We find that both param SF and param TH can reproduce the forward-angle scattering, even though these class C(-1) parametrizations are usually considered too simplistic to be useful for calculations of DCSs. We find that an ultrasimplistic param THz, which is param TH with a phase of zero, can also reproduce the glory scattering at forward angles. The S matrix elements for param THz are real and consist of five nonzero equal values, given by S(J) = 0.02266, for the window, J = 21(1)25. Param THz is sufficiently simple that we can derive closed forms for the partial wave scattering amplitude, f(?(R)), and the near-side (N) and far-side (F) subamplitudes. We show that window representations of f(?(R)) provide important insights into the range of J values that contribute to the reaction dynamics. Other theoretical techniques used are NF theory for the analysis of DCSs and full and NF local angular momentum theory, in both cases including up to three resummations of f(?(R)) before making the NF decomposition. Finally, we investigate the accuracy of various semiclassical glory theories for the DCS of param L. By varying one phase parameter for param L, we show that the uniform semiclassical approximation is accurate from ?(R) = 0° to close to ?(R) = 180°. Our approach is an example of a "weak" form of Heisenberg's S matrix program, which does not use a potential energy surface(s); rather it focuses on the properties of the S matrix. Our method is easy to apply to DCSs from experimental measurements or from computer simulations. PMID:22876759

Shan, Xiao; Connor, J N L

2012-11-26

408

Origin and Evolution of the Elements  

NASA Astrophysics Data System (ADS)

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.

McWilliam, Andrew; Rauch, Michael

2004-09-01

409

On the linear representations of the symmetry groups of single-wall carbon nanotubes  

E-print Network

The positions of atoms forming a carbon nanotube are usually described by using a system of generators of the symmetry group. Each atomic position corresponds to an element of the set Z x {0,1,...,n} x {0,1}, where n depends on the considered nanotube. We obtain an alternate rather different description by starting from a three-axes description of the honeycomb lattice. In our mathematical model, which is a factor space defined by an equivalence relation in the set {(v_0,v_1,v_2)\\in Z^3 | v_0+v_1+v_2\\in {0,1}}, the neighbours of an atomic position can be described in a simpler way, and the mathematical objects with geometric or physical significance have a simpler and more symmetric form. We present some results concerning the linear representations of single-wall carbon nanotubes in order to illustrate the proposed approach.

Nicolae Cotfas

2006-02-08

410

Elements of tropical Pacific decadal variability  

E-print Network

and content by: njamin S. Giese (C Chair of Committee) ~ ~(V Gerald R. North (Member) Wilford D. Gardner (Head of Department) ing Chang Co-Chair of Committee) May 2003 Major Subject Oceanography ABSTRACT Elements of Tropical Pacific Decadal.... Tropical Pacific Decadal Variability and the 1976-77 Climate Shift B. Elements of Spiciness Decadal Variability. . . . . . . . C. Elements of Isopycnal Depth Decadal Variability. . . . IV CONCLUSIONS . A. Summary B. Discussion . . C. Future...

Fuckar, Neven-Stjepan

2003-01-01

411

Grouping Dinosaurs  

NSDL National Science Digital Library

In this classroom activity, young students are introduced to sets and subsets. The activity opens with background information for teachers about cladistics. After brainstorming different ways to group the class itself, students work in small groups to identify subsets of coins. The groups then complete a worksheet that challenges them to group dinosaurs into sets and subsets and share their results with the class.

412

Trace element concentrations in blood of harbor seals (Phoca vitulina) from the Wadden Sea.  

PubMed

Concentrations of 23 elements (Be, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Pd, Cd, Sn, Pt, Pb) were evaluated in whole blood samples of live harbor seals (Phoca vitulina) from two different locations in the Wadden Sea, the Lorenzenplate in Germany, and the Danish island Rømø. Elemental blood levels were compared to data from literature of seals, other marine mammals and humans. While homeostatically controlled elements showed no differences, concentrations of As, Cr, Mn, Mo, Se, and V were higher than human levels. Furthermore, animals from both locations showed significant geographical differences in whole blood concentrations of Al, Mn, Cu, and Pt. These findings could be explained by differences in feeding areas. The element pattern was not affected by gender. In conclusion, these findings indicate an impact of the environment on biochemical blood parameters of the harbor seals. The significant differences of elements in blood samples of two groups of seals, which were associated with geographical variations of prey support the use of element pattern in blood as tool for investigation of environmental impact on seals. PMID:18191988

Griesel, Simone; Kakuschke, Antje; Siebert, Ursula; Prange, Andreas

2008-03-25

413

Distortion elements for surface homeomorphisms 3 janvier 2013  

E-print Network

Distortion elements for surface homeomorphisms E. Militon 3 janvier 2013 Abstract Let S be a compact orientable surface and f be an element of the group Homeo0(S) of homeo- morphisms of S isotopic, where dn is the diameter of ~fn (D), then the homeomorphism f is a distortion element of the group Homeo

Paris-Sud XI, Université de

414

The generalization of the Schur multipliers of Bieberbach groups  

NASA Astrophysics Data System (ADS)

The Schur multiplier is the second homology group of a group. It has been found to be isomorphic to the kernel of a homomorphism which maps the elements in the exterior square of the group to the elements in its derived subgroup. Meanwhile, a Bieberbach group is a space group which is a discrete cocompact group of isometries of oriented Euclidean space. In this research, the Schur multipliers of Bieberbach groups with cyclic point group of order two of finite dimension are computed.

Masri, Rohaidah; Hassim, Hazzirah Izzati Mat; Sarmin, Nor Haniza; Ali, Nor Muhainiah Mohd; Idrus, Nor'ashiqin Mohd

2014-12-01

415

On Finite Groups and Finite Fields.  

ERIC Educational Resources Information Center

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)

Reid, J. D.

1991-01-01

416

The Polycomb group — no longer an exclusive club?  

Microsoft Academic Search

Polycomb group (PcG) proteins maintain silencing at target loci in higher eukaryotes but recent evidence suggests that about half of these proteins are also required for maintenance of activation at homeotic loci. We suggest that PcG and trithorax group response elements should acquire a new name, ‘maintenance elements’, to reflect the dual function of regulatory elements that bind both groups

Hugh W Brock; Maarten van Lohuizen

2001-01-01

417

Summary Report of Working Group 2: Computation  

SciTech Connect

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.

Stoltz, P. H. [Tech-X Corporation, Boulder, CO 80303 (United States); Tsung, R. S. [Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095 (United States)

2009-01-22

418

Summary Report of Working Group 2: Computation  

NASA Astrophysics Data System (ADS)

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.

Stoltz, P. H.; Tsung, R. S.

2009-01-01

419

Group Signatures  

Microsoft Academic Search

Abstract. In this paper we present a new type of signature for a group of persons, called a group signature, which has the following propertjes: (i) only members,of the group can sign messages; (ii) the receiver can verify that it is a valid group signaa~e, but cannot discover which gr~up member made (i) if necessary, the signature can be \\

David Chaum; Eugène Van Heyst

1991-01-01