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1

Cone angles of ligands which are compounds of group-IV and group-V elements  

SciTech Connect

The cone angles theta (a steric characteristic, which expresses the degree of filling of a coordination sphere by a ligand) have been calculated for 610 ligands. The ligands considered have an AB'/sub 3/ or A(OB')/sub 3/ formula and a tetrahedral (with respect to A in an M-AB/sub 3/' fragment of a complex, where M is the coordinating metal) geometry, where A = N, P, As, Sb, Bi, C, Si, Ge, Sn, or Pb, and B' is an alkyl, cycloalkyl, aryl, alkylaryl, or arylalkyl group. The known cone angles of ligands based on phosphorus, which were determined on molecular models, have been corrected, and they have been used to calculate the effect covalent and van der Waals radii of the B' groups. The cone angles were calculated from the effective radii and the M-A internuclear distances. Such a procedure provides for the standardization and comparability of the steric characteristics obtained. The cone angles are identical or close for adjacent elements in groups IV and V (N and C, P and Si, As and Ge, Sb and Sn, Bi and Pb). When A is replaced by lower-lying elements within a group, the cone angles decrease, these decreases being greater, the greater is the size of the ligand. The changes accompanying the transition from nitrogen (or carbon) to phosphorus (or silicon) are especially great. The cone angles of diethylaniline and methyldiphenylamine correspond to that of triphenylphosphine, and the cone angles of dimethylaniline and diphenylamine correspond to that of tributyl-phosphine. The variation of the cone angle as a function of the central metal atom has been examined, and it has been shown that the values of the cone angles established for the compounds of nickel can be used for complexes of all the other transition metals, with the exception of the elements found at the beginning of the transition series.

Imyanitov, N.S.

1986-07-01

2

Investigation of magnetic properties induced by group-V element in doped ZnO.  

PubMed

For the potential applications in spintronics, we examine systematically the electronic properties of group-V elements (X) doped ZnO to investigate the magnetic properties induced by X based on density functional theory calculations. Our results indicates that X atoms doped in the form of a substitutional X atom at an O anion site (XO) and at a Zn cation site combining with two Zn vacancies (XZn-2VZn complex) under different circumstances can introduce magnetism. The magnetism comes from the p-p and p-d coupling interaction between the dopant X-p orbitals and the host O-2p and Zn-3d orbitals. The stability of the ferromagnetism (FM) phase induced by XO defects decreases with the increase of dopant atomic number due to the lower electronegativity value, which can be interpreted by the phenomenological band-coupling model. The origin of the magnetism induced by XZn-2VZn is similar to that of the Zn vacancy (VZn) in ZnO and comes from the O-2p orbitals dominantly. The FM stability introduced by XZn-2VZn decreases with the order N < Sb < As < P, which is ascribed to the delocalization of the O-2p orbitals. The results mean that 3p/4p/5p dopants could also make ZnO materials into diluted magnetic semiconductors. PMID:23455330

Lu, Ying-Bo; Dai, Ying; Guo, Meng; Yu, Lin; Huang, Baibiao

2013-04-14

3

Junctions in axial III-V heterostructure nanowires obtained via an interchange of group III elements.  

PubMed

We present an investigation of the morphology and composition of novel types of axial nanowire heterostructures where Ga(x)In(1-x)As is used as barrier material in InAs nanowires. Using aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray analysis we demonstrate that it is possible to grow junctions by changing the group III elements, and we find that a substantial fraction of Ga can be incorporated in axial InAs/Ga(x)In(1-x)As/InAs, retaining straight nanowire configurations. We explain how the adatoms are transferred to the incorporation site at the growth interface via two different routes, (1) interface diffusion and (2) volume diffusion through the catalyst particle. PMID:19842690

Krogstrup, Peter; Yamasaki, Jun; Sørensen, Claus B; Johnson, Erik; Wagner, Jakob B; Pennington, Robert; Aagesen, Martin; Tanaka, Nobuo; Nygård, Jesper

2009-11-01

4

Theoretical and Materials Chemistry of Some Group III and V Elements  

NASA Astrophysics Data System (ADS)

The theoretical and material aspects of some group III and V compounds have been investigated. Phosphaborane clusters were investigated by modified neglect of differential overlap semi-empirical molecular orbital calculations (MNDO -SCF) to better understand important structural, electronic, and thermodynamic properties of these experimentally difficult species. The structural, thermodynamic and electronic properties of 111 phosphapentaborane cluster compounds have been calculated via MNDO-SCF. The geometry-optimized, minimum energy structures for all of the known and structurally characterized phosphaborane systems have been calculated. In each case, exceptionally good agreement was observed between the experimentally determined and the calculated structural parameters. Calculations for five classes of phosphapentaborane clusters have been completed and have been related to experimentally proposed structural types. Predictions concerning structural and chemical reactivities for unknown and known phosphapentaborane compounds have been made based on these MO calculations. Production of important thin film materials was discussed relative to chemical vapor deposition (CVD). Advantages of CVD over older thermodynamic deposition techniques were described. The CVD process has been briefly reviewed through seven primary steps. The importance of new source materials which meet stringent industrial requirements have been detailed relative to environmental, occupational safety, and contaminations considerations. Thin films of pure aluminum, aluminum boride and aluminum oxide have been prepared from the chemical vapor deposition (CVD) of rm Al(BH_4)_3, and rm AlH_2(BH_4) cdot N(CH_3)_3, on both single crystals and thermally sensitive substrates. Films were characterized by EDX, AES, SEM, XRD, and resistivity measurements and ranged in thickness from 500 A to 2 mu m. Each type of film was shown by AES to be compositionally uniform in the bulk sample with only very shallow surface contaminations of oxygen and carbon. Both source compounds were, in general, relatively thermally stable, volatile, air-sensitive liquids, thus providing nearly ideal precursor properties for chemical vapor deposition. Organophosphorus sources for the chemical vapor deposition (CVD) of indium phosphide have been examined with MNDO-SCF theoretical calculations in order to predict important depositional parameters such as decomposition temperature and temperature selectivities. Decomposition temperatures and temperature selectivities for the three known organophosphorus sources, t-butyl phosphine (TBP), i-butyl phosphine (IBP) and bisphosphinoethane (BPE), have been shown to match MNDO's predicted values, indicating that MNDO can be used as a first test for the suitability of organophosphorus compounds. Optimized depositional parameters for TBP, IBP and BPE were presented. Alternative phosphorus sources with enhanced depositional properties have been identified and analyzed in terms of decomposition temperature and optimized deposition conditions. Cyclohexyl phosphine (PCH) has been used in conjunction with trimethyl indium (TMI) to deposit polycrystalline indium phosphide with no carbon incorporation. Attempted indium phosphide depositions using dichloro-t-butyl phosphine (DCTBP) and TMI yielded both an etching of the InP(100) surface (73.4 A/sec) and polycrystalline rm Cu_3P. .

Glass, John Arthur, Jr.

5

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

2013-09-01

6

Gas chromatography of chlorides and bromides of III-, IV and V-group elements in the periodic table  

Microsoft Academic Search

Die Theorie über die Beziehung zwischen Retentionsvolumen und Siedepunkt in der Gas-Chromatographie wurde auf die Retentionsvolumina der Bromide der IV. sowie der Chloride und Bromide der III. und V. Gruppe angewendet (in Fortführung der früheren Arbeit über die Chloride der IV. Gruppe). Der scheinbare Löslichkeitsparameter des Lösungsmittels (ßdS) wurde aufgetrennt in den Unregelmäßigkeitsparameter (ß) und den Löslichkeitsparameter des Lösungsmittels (dS).

Kiyoteru Otozai; Itiro Tohyama

1975-01-01

7

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

NASA Astrophysics Data System (ADS)

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

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

2005-08-01

8

Group Theoretical Classification of Chemical Elements.  

National Technical Information Service (NTIS)

The method of classification of chemical elements, based on group symmetry principles, is compared with element properties. Elements are considered to be states of a single quantum system, the atomic structure being ignored. Elements treated as states of ...

V. M. Byakov V. I. Kulakov Y. B. Rumer A. L. Fet

1977-01-01

9

In search of multiple bonding in the heavier main group III-V elements: Synthesis of aluminum and gallium amides and related compounds  

SciTech Connect

A key objective of this thesis is the examination of possible multiple bonding between the elements Al-N and Ga-N where the adjacent nitrogen lone pair and empty metal p-orbital may enable multiple bonding to occur. The reactions of trimethylaluminum or trimethylgallium with bulky primary amines are described in Chapter 1. The data reveal differences in the reactivity of aluminum and gallium. The structure of the aluminum analogue of borazine is presented. In Chapter 2, the first reported structures of trisdialkylamides of aluminum or gallium are presented. The transamination reaction involving the trisdialkylaluminumamide is described. Results from the treatment of AlMe[sub 3] with 2 equiv. of HNPh[sub 2] are presented. The synthesis and characterization of GaTrip[sub n]X[sub 3[minus]n] (Trip = 2,4,6-triisopropylphenyl; X = Br, Cl) is described in Chapter 3. The derivatives GaTrip[sub 2]Br and GaTrip[sub 2]Cl are the first examples of monomeric organogalliumhalides. Two compounds, the first structurally characterized monoaminogallanes, are presented in Chapter 4. The data suggests a Ga-N barrier to rotation of [approximately]9--10 kcal mol[sup [minus]1]. A ring flip barrier of [approximately]18 kcal mol[sup [minus]1] is also observed. A compound described as a mixed amino/ammonium gallate is discussed. The theme established for Al-N and Ga-N species is extended to a compound involving a novel cluster with a Ga-P framework in Chapter 5. The compound has a Ga[sub 4]P[sub 5] core and is the first example of a main group 3--5 cluster for which the overall ratio of substituents to the main group element is unity. The cluster contains a gallium center and two phosphorus centers that are three-coordinate. The synthesis and characterization of two very bulky diorganomagnesium reagents are described in Chapter 6. The structure of an unassociated 3-coordinate magnesiate species is presented. The magnesiate core is isoelectronic to trisorgano-aluminum or -gallium species.

Waggoner-Andrews, K.M.

1992-01-01

10

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

11

Tetragonal allotrope of group 14 elements.  

PubMed

Group 14 elements (C, Si, and Ge) exist as various stable and metastable allotropes, some of which have been widely applied in industry. The discovery of new allotropes of these elements has long attracted considerable attention; however, the search is far from complete. Here we computationally discovered a tetragonal allotrope (12 atoms/cell, named T12) commonly found in C, Si, and Ge through a particle swarm structural search. The T12 structure employs sp(3) bonding and contains extended helical six-membered rings interconnected by pairs of five- and seven-membered rings. This arrangement results in favorable thermodynamic conditions compared with most other experimentally or theoretically known sp(3) species of group 14 elements. The T12 polymorph naturally accounts for the experimental d spacings and Raman spectra of synthesized metastable Ge and Si-XIII phases with long-puzzling unknown structures, respectively. We rationalized an alternative experimental route for the synthesis of the T12 phase via decompression from the high-pressure Si- or Ge-II phase. PMID:22803841

Zhao, Zhisheng; Tian, Fei; Dong, Xiao; Li, Quan; Wang, Qianqian; Wang, Hui; Zhong, Xin; Xu, Bo; Yu, Dongli; He, Julong; Wang, Hui-Tian; Ma, Yanming; Tian, Yongjun

2012-07-19

12

The Enumeration of Fully Commutative Elements of Coxeter Groups  

Microsoft Academic Search

A Coxeter group element w is fully commutative if any reduced expression for w can be obtained from any other via the interchange of commuting generators. For example, in the symmetric group of degree n, the number of fully commutative elements is the nth Catalan number. The Coxeter groups with finitely many fully commutative elements can be arranged into seven

John R. Stembridge

1998-01-01

13

Working Group on Cartographic Coordinates and Rotational Elements  

Microsoft Academic Search

The 2003 report of the IAU\\/IAG Working Group on Cartographic Coordinates and Rotational Elements has appeared in Celestial Mechanics and Dynamical Astronomy(2005)volume 91, part 3-4, pages 203-215. The Working Group continues to maintain and update the information for cartographic coordinates and rotational elements for the Sun, Moon, planets, satellites, asteroids, and comets. A report is published treannually. A web site

P. Kenneth Seidelmann; B. A. Archinal; M. F. A'Hearn; D. P. Cruikshank; J. L. Hilton; H. U. Keller; R. J. Oberst; J. L. Simon; P. Stooke; D. J. Tholen; P. C. Thomas

2007-01-01

14

On linear groups in which all elements can be decomposed in Jordan products  

Microsoft Academic Search

Let k be an algebraically closed field of arbitrary characteristic and let GL(n, k) b'e the group of all automorphisms of an n-dimensional vector space V over k. The elements of GL(n, k) are considered as the non-singular square matrices of degree n with coefficients in k. An element x of GL(n, k) is uniquely expressed as x = x

Shigeaki Tôgô

1961-01-01

15

Experiments on the sputtering of group VI elements  

Microsoft Academic Search

At the last REI** 1st Intl. Conf. on Radiation Effects in Insulators, held in Arco, Lago di Garda, Italy (30.6. 1981). conference, we reported that 30...300 keV He+ ions impinging on elemental solid sulfur cause tremendous erosion, corresponding to sputtering yields of 104 to 106 sulfur atoms per incident He ion. In the present work, these experiments were repeated at

D. Fink; J. P. Biersack; M. Städele; K. Tjan; R. A. Haring; A. E. de Vries

1984-01-01

16

Summary of the TeV33 working group  

SciTech Connect

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

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

1996-10-01

17

Homocatenation of Metal and Metalloid Main Group Elements  

NASA Astrophysics Data System (ADS)

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

Hill, Michael S.

18

Ab initio predictions of atomic properties of element 120 and its lighter group-2 homologues  

NASA Astrophysics Data System (ADS)

The ionization potentials, excitation energies, and electron affinity of superheavy element 120 and the polarizabilities of its neutral and ionized states are calculated. Relativity is treated within the four-component Dirac-Coulomb formalism; Breit or Gaunt terms are added in some cases. Electron correlation is included via the intermediate Hamiltonian Fock-space coupled cluster method for the spectra and ionization potentials and via the single reference coupled cluster singles and doubles with perturbative triples [CCSD(T)] approach for the electron affinities and polarizabilities. To assess the accuracy of the results, the atomic properties of the lighter homologues, Ba and Ra, are also calculated. Very good agreement with available experimental values is obtained, lending credence to the predictions for element 120. The atomic properties in group 2 are largely determined by the valence ns orbital, which experiences relativistic stabilization and contraction in the heavier group-2 elements. As a result, element 120 is predicted to have a relatively high ionization potential (5.851 eV), similar to that of Sr, and rather low electron affinity (0.021 eV) and polarizability (163 a.u.), comparable to those of Ca. The adsorption enthalphy of element 120 on Teflon, which is important for possible future experiments on this atom, is estimated as 35.4 kJ/mol, the lowest among the elements considered here.

Borschevsky, A.; Pershina, V.; Eliav, E.; Kaldor, U.

2013-02-01

19

Working Group on Cartographic Coordinates and Rotational Elements  

NASA Astrophysics Data System (ADS)

The 2003 report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements has appeared in Celestial Mechanics and Dynamical Astronomy(2005)volume 91, part 3-4, pages 203-215. The Working Group continues to maintain and update the information for cartographic coordinates and rotational elements for the Sun, Moon, planets, satellites, asteroids, and comets. A report is published treannually. A web site is maintained at http://extranet.astrogeology.wr.usgs.gov/Projects/WGCCRE with the up-to-date information. It is anticipated that the next report will include updates for Saturn (rotation rate) and all of the Saturnian moons, additions for the newly visited comets and asteroids, and a clarification of the Moon's coordinate systems (the mean Earth/polar axis system needs to be defined more precisely).

Seidelmann, P. Kenneth; Archinal, B. A.; A'Hearn, M. F.; Cruikshank, D. P.; Hilton, J. L.; Keller, H. U.; Oberst, R. J.; Simon, J. L.; Stooke, P.; Tholen, D. J.; Thomas, P. C.

2007-03-01

20

Airborne Particulate Matter, Platinum Group Elements and Human Health  

Microsoft Academic Search

\\u000a The platinum group elements (PGE), platinum (Pt), palladium (Pd) and rhodium (Rh), are emitted in small amounts in the exhaust\\u000a of automobiles equipped with catalytic converters, which employ these metals as catalysts to convert nitrous oxide (NO\\u000a x\\u000a ), carbon monoxide (CO) and hydrocarbons (HCs) into more benign forms prior to their release. While catalytic converters have\\u000a reduced these noxious

Clare L. S. Wiseman; Fathi Zereini

21

Removal of platinum group elements in an estuarine turbidity maximum  

Microsoft Academic Search

The particle–water interactions of Rh(III), Pd(II) and Pt(IV) (or platinum group elements, PGE) have been studied in an estuarine turbidity maximum (Tamar, south west England) by spiking suspensions with mixed standards to concentrations of 10 ?g L?1 and analysing acidified filtrates and digested particles by ICP–MS. Adsorption of PGE to estuarine particles was defined by the Frendlich equation, with Freundlich

Andrew Turner; Kai Ting Wu

2007-01-01

22

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

23

Main-group and transition-element IRMOF homologues.  

PubMed

A simple two-component procedure was developed to synthesize not only classical zinc-based IRMOFs represented by MOF-5 but also the cobalt and beryllium homologues of this most prominent MOF. The procedure is the first manifestation of mirroring the IRMOF series with other metal centers taken from main-group as well as transition-metal elements. Because of the existence of many suitable precursors, the procedure promises the generation of a large number of IRMOF homologues. Since the IRMOF series together with the MIL series is the MOF group with the largest number of representatives, the possibility of choosing the metal centers of the secondary building units from an extended set will tremendously expand the number of obtainable structures in a predictive, crystal-engineering-type way. Use of metal centers other than zinc will allow the addition of new features to the existing IRMOF structures, such as magnetic properties in the example of cobalt. PMID:20698648

Hausdorf, Steffen; Baitalow, Felix; Böhle, Tony; Rafaja, David; Mertens, Florian O R L

2010-08-18

24

P-Element Homing Is Facilitated by engrailed Polycomb-Group Response Elements in Drosophila melanogaster  

PubMed Central

P-element vectors are commonly used to make transgenic Drosophila and generally insert in the genome in a nonselective manner. However, when specific fragments of regulatory DNA from a few Drosophila genes are incorporated into P-transposons, they cause the vectors to be inserted near the gene from which the DNA fragment was derived. This is called P-element homing. We mapped the minimal DNA fragment that could mediate homing to the engrailed/invected region of the genome. A 1.6 kb fragment of engrailed regulatory DNA that contains two Polycomb-group response elements (PREs) was sufficient for homing. We made flies that contain a 1.5kb deletion of engrailed DNA (en?1.5) in situ, including the PREs and the majority of the fragment that mediates homing. Remarkably, homing still occurs onto the en?1. 5 chromosome. In addition to homing to en, P[en] inserts near Polycomb group target genes at an increased frequency compared to P[EPgy2], a vector used to generate 18,214 insertions for the Drosophila gene disruption project. We suggest that homing is mediated by interactions between multiple proteins bound to the homing fragment and proteins bound to multiple areas of the engrailed/invected chromatin domain. Chromatin structure may also play a role in homing.

Cheng, Yuzhong; Kwon, Deborah Y.; Arai, Allison L.; Mucci, Diane; Kassis, Judith A.

2012-01-01

25

P-element homing is facilitated by engrailed polycomb-group response elements in Drosophila melanogaster.  

PubMed

P-element vectors are commonly used to make transgenic Drosophila and generally insert in the genome in a nonselective manner. However, when specific fragments of regulatory DNA from a few Drosophila genes are incorporated into P-transposons, they cause the vectors to be inserted near the gene from which the DNA fragment was derived. This is called P-element homing. We mapped the minimal DNA fragment that could mediate homing to the engrailed/invected region of the genome. A 1.6 kb fragment of engrailed regulatory DNA that contains two Polycomb-group response elements (PREs) was sufficient for homing. We made flies that contain a 1.5 kb deletion of engrailed DNA (en(?1.5)) in situ, including the PREs and the majority of the fragment that mediates homing. Remarkably, homing still occurs onto the en(?1. 5) chromosome. In addition to homing to en, P[en] inserts near Polycomb group target genes at an increased frequency compared to P[EPgy2], a vector used to generate 18,214 insertions for the Drosophila gene disruption project. We suggest that homing is mediated by interactions between multiple proteins bound to the homing fragment and proteins bound to multiple areas of the engrailed/invected chromatin domain. Chromatin structure may also play a role in homing. PMID:22276200

Cheng, Yuzhong; Kwon, Deborah Y; Arai, Allison L; Mucci, Diane; Kassis, Judith A

2012-01-19

26

Elements of class groups and Shafarevich-Tate groups of elliptic curves  

Microsoft Academic Search

The problem of estimating the number of imaginary quadratic fields\\u000awhose ideal class group has an element of order ??2$ is\\u000aclassical in number theory. Analogous questions for quadratic twists\\u000aof elliptic curves have been the focus of recent interest. Whereas\\u000aworks of C. Stewart and J. Top [ST], and of F. Gouvêa and\\u000aB. Mazur [GM] address the nontriviality

Antal Balog; Ken Ono

2003-01-01

27

Mahowaldean families of elements in stable homotopy groups revisited  

NASA Astrophysics Data System (ADS)

In the mid 1970s Mark Mahowald constructed a new infinite family of elements in the 2-component of the stable homotopy groups of spheres, [eta]j[set membership][pi]Sj2 (S0)(2) [M]. Using standard Adams spectral sequence terminology (which will be recalled in Section 3 below), [eta]j is detected by h1hj[set membership]Ext2,*[script A] (Z/2, Z/2). Thus he had found an infinite family of elements all having the same Adams filtration (in this case, 2), thus dooming the so-called Doomsday Conjecture. His constructions were ingenious: his elements were constructed as composites of pairs of maps, with the intermediate spaces having, on one hand, a geometric origin coming from double loopspace theory and, on the other hand, mod2 cohomology making them amenable to Adams Spectral Sequence analysis and suggesting that they were related to the new discovered Brown-Gitler spectra [BG].In the years that followed, various other related 2-primary infinite families were constructed, perhaps most notably (and correctly) Bruner's family detected by h2h2j[set membership] Ext3,*[script A](Z/2, Z/2) [B]. An odd prime version was studied by Cohen [C], leading to a family in [pi]S[low asterisk](S0)(p) detected by h0bj[set membership] Ext3,*[script A] (Z/p, Z/p) and a filtration 2 family in the stable homotopy groups of the odd prime Moore space. Cohen also initiated the development of odd primary Brown-Gitler spectra, completed in the mid 1980s, using a different approach, by Goerss [G], and given the ultimate ‘modern’ treatment by Goerss, Lannes and Morel in the 1993 paper [GLM]. Various papers in the late 1970s and early 1980s, e.g. [BP, C, BC], related some of these to loopspace constructions.Our project originated with two goals. One was to see if any of the later work on Brown-Gitler spectra led to clarification of the original constructions. The other was to see if taking advantage of post Segal Conjecture knowledge of the stable cohomotopy of the classifying space BZ/p would help in constructing new families at odd primes, in particular a conjectural family detected by h0hj[set membership] Ext2,*[script A] (Z/p, Z/p). (This followed a paper [K1] by one of us on 2 primary families from this point of view.)

Hunter, David J.; Kuhn, Nicholas J.

1999-09-01

28

Thermodynamic properties of the Group 1A elements  

SciTech Connect

This review describes thermodynamic properties of condensed phases of the alkali metals, excluding francium for which the amount of information is too limited. The properties considered are: heat capacities from 0 to 1600 K, temperatures and enthalpies of fusion and martensitic transformation in Li and Na; discussion of the Debye temperature and electronic heat capacity coefficient at absolute zero temperature is also included. The paper is the second part of a series. Similar to previous assessment of the IIA group [93ALC/CHA], this paper considers original studies, especially with respect to factors which influence the accuracy and reliability of results. Recommendations derived from such analyses are compared with most advanced previous reviews made at the Institute for High Temperatures (Moscow) [70SHP/YAK], [82GUR] and the National Institute of Standards and Technology (Washington) [85JAN]. The properties of individual elements of the group are compared and suggestions are made for experimental studies which should improve poorly measured quantities. The review is supplemented by an IBM PC database which contains references, assessed data, brief description of studies and has facilities for fitting and plotting of data and for adding new information.

Alcock, C.B.; Itkin, V.P. [Univ. of Toronto (Canada); Chase, M.W. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

1994-05-01

29

KASCADE-Grande measurements of energy spectra for elemental groups of cosmic rays  

NASA Astrophysics Data System (ADS)

The KASCADE-Grande air shower experiment [1] consists of, among others, a large scintillator array for measurements of charged particles, N, and of an array of shielded scintillation counters used for muon counting, N?. KASCADE-Grande is optimized for cosmic ray measurements in the energy range 10 PeV to about 2000 PeV, where exploring the composition is of fundamental importance for understanding the transition from galactic to extragalactic origin of cosmic rays. Following earlier studies of the all-particle and the elemental spectra reconstructed in the knee energy range from KASCADE data [2], we have now extended these measurements to beyond 200 PeV. By analysing the two-dimensional shower size spectrum N vs. N? for nearly vertical events, we reconstruct the energy spectra of different mass groups by means of unfolding methods over an energy range where the detector is fully efficient. The procedure and its results, which are derived based on the hadronic interaction model QGSJET-II-02 and which yield a strong indication for a dominance of heavy mass groups in the covered energy range and for a knee-like structure in the iron spectrum at around 80 PeV, are presented. This confirms and further refines the results obtained by other analyses of KASCADE-Grande data, which already gave evidence for a knee-like structure in the heavy component of cosmic rays at about 80 PeV [3].

Apel, W. D.; Arteaga-Velázquez, J. C.; Bekk, K.; Bertaina, M.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Cossavella, F.; Daumiller, K.; de Souza, V.; Di Pierro, F.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuchs, B.; Fuhrmann, D.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huber, D.; Huege, T.; Kampert, K.-H.; Kang, D.; Klages, H. O.; Link, K.; ?uczak, P.; Ludwig, M.; Mathes, H. J.; Mayer, H. J.; Melissas, M.; Milke, J.; Mitrica, B.; Morello, C.; Oehlschläger, J.; Ostapchenko, S.; Palmieri, N.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schieler, H.; Schoo, S.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Ulrich, H.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.

2013-07-01

30

New aspects in the chemistry of low-coordinated inter-element compounds of heavier Group 15 elements  

Microsoft Academic Search

Recent results obtained in the studies of the author and co-workers on the synthesis and properties of doubly bonded systems between heavier Group 15 elements are described together with a brief historical survey on the chemistry of low-coordinated heavier Group 15 elements. The first stable distibene and dibismuthene were successfully synthesized by taking an advantage of kinetic stabilization using new

Norihiro Tokitoh

2000-01-01

31

Elemental Abundance Studies of CP Stars the Silicon Group  

Microsoft Academic Search

An analysis of the silicon CP star HD 168733 is presented using ATLAS9 model atmospheres and observational material taken with the EBASIM spectrograph attached to the Jorge Sahade 2.15-m telescope at CASLEO. The light elements are deficient except silicon which is overabundant. The iron peak and the heavy elements are all overabundant by large factors.

Z. López-García; E. P. González; S. Maris Malaroda

2006-01-01

32

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

SciTech Connect

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 100 eV and 30 keV 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 10 keV. 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 30 keV, 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. [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Powell, C. J.; Penn, D. R. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370 (United States)

2008-03-15

33

Radiation Effects in the Chemistry of Group IVB Elements (Silicon, Germanium, Tin, and Lead)  

Microsoft Academic Search

Data concerning the effect of ionising radiation on the principal reactions in organometallic synthesis involving Group IVB elements are considered: radiolysis of organometallic compounds of Group IVB elements, addition to the C=C bond, redistribution of radicals, reactions leading to the substitution of functional groups or organic substituents at the metal atom, reactions involving the organic group, and direct synthesis of

N. V. Fomina; N. I. Sheverdina; K. A. Kocheshkov

1978-01-01

34

Platinum group elements in airborne particles in Mexico City.  

PubMed

Automobile exhaust catalysts using platinum group elements (PGE) have been mandatory on new cars in the Mexico City Metropolitan Area (MCMA) since 1991. Platinum, Pd, Rh, Ir, and Os concentrations and the isotopic composition of Os were determined in PM10 samples from the MCMA. Samples were prepared by isotope dilution NiS fire assay, and analysis was performed by magnetic sector ICP-MS using a single collector instrument for Pt, Pd, Rh, and Ir analysis and a multicollector instrument for Os analysis. Pt, Pd, and Rh concentrations at a downtown location (Merced) increased from < or =1.7 pg of Pt m(-3), 2.7 (4.0) pg of Pd m(-3), and 1.2+/-0.9 pg of Rh m(-3) in 1991 to 9.6 +/- 1.8 pg of Pt m(-3), 10.2+/-1.8 pg of Pd m(-3), and 2.8 +/-0.6 pg of Rh m(-3) in 2003. Concentrations at five sites in MCMA in 2003 averaged 9.3+/-1.9 pg of Pt m(-3), 11+/-4 pg of Pd m(-3), and 3.2+/- 1.0 pg of Rh m(-3). In contrast, Ir and Os concentrations and Os isotopic composition remained relatively constant and were 0.08+/-0.04 pg of Ir m(-3), 0.030 +/-0.007 pg of Os m(-3), and 0.60+/-0.04, respectively, in the MCMA in 2003. Elevated Pt, Pd, and Rh concentrations in the MCMA are attributed to automobile catalysts. A Pt-Pd-Rh concentration peak in 1993 suggests that early catalysts emitted a larger amount of PGE, possibly due to factors inherent in the technology or the use of inappropriate gasoline. Therefore, this study suggests that the current introduction of automobile catalysts in developing countries may result in elevated PGE concentrations if it is not accompanied by infrastructures and policy measures supporting their efficient use. PMID:17256494

Rauch, Sebastien; Peucker-Ehrenbrink, Bernhard; Molina, Luisa T; Molina, Mario J; Ramos, Rafael; Hemond, Harold F

2006-12-15

35

Trace Element Levels in Hair of a Population Group Living in a Small Coastal Town.  

National Technical Information Service (NTIS)

Mercury and other trace elements were measured in hair samples collected from subjects of a population group having an average annual fish consumption significantly higher than that for the Italian population. The determination of the trace elements was c...

G. Ingrao G. P. Santaroni

1988-01-01

36

Energy spectrum and elemental composition of cosmic rays in the PeV region  

NASA Astrophysics Data System (ADS)

KASCADE (KArlsruhe Shower Core and Array DEtector) is determining flux spectra for different primary mass groups to disentangle the knee feature of the primary cosmic-ray energy spectrum. The energy spectra of the light element groups result in a knee-like bending and a steepening above the knee. The topology of the individual knee positions suggests a rigidity dependence. To proof the rigidity dependence the KASCADE array is now extended by a factor 10 in area. The major goal of KASCADE-Grande is the observation of the 'iron-knee' in the cosmic-ray spectrum at around 100 PeV which is expected following the KASCADE observations. PACS: 98.70.Sa Cosmic rays

Ulrich, H.; Glasstetter, R.; Antoni, T.; Apel, W. D.; Badea, F.; Bekk, K.; Bercuci, A.; Bertaina, M.; Blümer, H.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Büttner, C.; Chiavassa, A.; Chilingarian, A.; Daumiller, K.; Doll, P.; Engel, R.; Engler, J.; Feßler, F.; Ghia, P. L.; Gils, H. J.; Haungs, A.; Heck, D.; Hörandel, J. R.; Kampert, K.-H.; Klages, H. O.; Kolotaev, Y.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Morello, C.; Müller, M.; Navarra, G.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Petcu, M.; Plewnia, S.; Rebel, H.; Risse, A.; Risse, M.; Roth, M.; Schatz, G.; Schieler, H.; Scholz, J.; Thouw, T.; Trinchero, G. C.; Valchierotti, S.; van Buren, J.; Vardanyan, A.; Walkowiak, W.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zagromski, S.

37

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

Microsoft Academic Search

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.

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

2005-01-01

38

Apsidal motion elements of six eccentric eclipsing binaries: V799 Cas, CO Cep, V1136 Cyg, V345 Lac, V364 Lac and V402 Lac  

NASA Astrophysics Data System (ADS)

The apsidal motion analysis of the eccentric eclipsing binaries: V799 Cas, CO Cep, V1136 Cyg, V345 Lac, V364 Lac and V402 Lac have been presented. The method described by Lacy (1992) has been used for the apsidal motion analysis. The apsidal motion periods have been found to be 1229 ± 235, 64,600 ± 20,000, 586 ± 6, 14,240 ± 2800, 3502 ± 582 and 242 ± 60 yr for V799 Cas, CO Cep, V1136 Cyg, V345 Lac, V364 Lac and V402 Lac, respectively. The corresponding internal structure constant, logk, for V799 Cas, V364 Lac and V402 Lac have been derived and compared to the theoretical values.

Bulut, ?brahim

2013-07-01

39

Differences between group X and group V secretory phospholipase A(2) in lipolytic modification of lipoproteins.  

PubMed

Secretory phospholipases A(2) (sPLA(2)s) are a diverse family of low molecular mass enzymes (13-18 kDa) that hydrolyze the sn-2 fatty acid ester bond of glycerophospholipids to produce free fatty acids and lysophospholipids. We have previously shown that group X sPLA(2) (sPLA(2)-X) had a strong hydrolyzing activity toward phosphatidylcholine in low-density lipoprotein (LDL) linked to the formation of lipid droplets in the cytoplasm of macrophages. Here, we show that group V sPLA(2) (sPLA(2)-V) can also cause the lipolysis of LDL, but its action differs remarkably from that of sPLA(2)-X in several respects. Although sPLA(2)-V released almost the same amount of fatty acids from LDL, it released more linoleic acid and less arachidonic acid than sPLA(2)-X. In addition, the requirement of Ca(2+) for the lipolysis of LDL was about 10-fold higher for sPLA(2)-V than sPLA(2)-X. In fact, the release of fatty acids from human serum was hardly detectable upon incubation with sPLA(2)-V in the presence of sodium citrate, which contrasted with the potent response to sPLA(2)-X. Moreover, sPLA(2)-X, but not sPLA(2)-V, was found to specifically interact with LDL among the serum proteins, as assessed by gel-filtration chromatography as well as sandwich enzyme-immunosorbent assay using anti-sPLA(2)-X and anti-apoB antibodies. Surface plasmon resonance studies have revealed that sPLA2-X can bind to LDL with high-affinity (K(d) = 3.1 nM) in the presence of Ca(2+). Selective interaction of sPLA(2)-X with LDL might be involved in the efficient hydrolysis of cell surface or intracellular phospholipids during foam cell formation. PMID:22706677

Kamitani, Shigeki; Yamada, Katsutoshi; Yamamoto, Shigenori; Ishimoto, Yoshikazu; Ono, Takashi; Saiga, Akihiko; Hanasaki, Kohji

2012-06-13

40

Finding of probable Tunguska Cosmic Body material: anomalies in platinum group elements in peat from the explosion area  

NASA Astrophysics Data System (ADS)

Further evidencies of a cometary nature of the 1908 Tunguska Cosmic Body (TCB) are presented. Earlier in the event layers of the Sphagnum fuscum peat from the explosion area, anomalies, relative to Earth-materials, of the elements H, C, and N—all abundant in comets—have been found [E.W. Kolesnikov, T. Boettger and N.V. Kolesnikova, Planet. Space Sci. 47 905 (1999); E.M. Kolesnikov, G. Longo, T. Boettger, N.V. Kolesnikova, P. Gioacchini, L. Forlani, R. Giampieri and R. Serra, Icarus 161 235 (2003).]. At the present work we revealed a sharp increase of concentrations of platinum group elements (PGE), REE and other elements in the event layers as well. Their ratios point to a cometary nature of the anomalies observed.

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

2005-04-01

41

X-ray standing wave investigations of Group III and V metal adsorption on Si(001)  

SciTech Connect

Investigations of atomic bonding, surface reconstruction, surface dynamics, and growth kinetics of group III and V metals on Si(001) are important for understanding the initial growth stage of III-V semiconductors on Si(001). Such studies can also provide valuable information for other important issues such as surfactant-mediated epitaxy, surface passivation and delta-doping layers. X-ray standing waves generated by dynamical Bragg diffraction were used as an element-specific structural probe for investigating Ga and Sb adsorption on Si(001). These high-resolution measurements reveal important quantitative structural information regarding the dimerized surface structures, and provide a stringent test for structural models proposed by various theoretical calculations. An overview of the X-ray standing wave technique and its application to surface structure and dynamics is presented.

Qian, Y.; Bedzyk, M.J. [Northwestern Univ., Evanston, IL (United States)]|[Argonne National Lab., IL (United States). Materials Science Div.; Lyman, P.F. [Northwestern Univ., Evanston, IL (United States)

1997-05-01

42

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

Microsoft Academic Search

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

K. P. Jochum; H. M. Seufert

1995-01-01

43

Bandgap tuning of mono- and bilayer graphene doped with group IV elements  

NASA Astrophysics Data System (ADS)

We report density functional theory band structure calculations of graphene doped with group IV elements. A bandgap as high as 2.13 eV is calculated for a single layer of graphene doped with Si while Ge and Sn doping reduce this bandgap for equal doping concentrations. Bilayers of doped graphene are also studied and it is found that the bandgap of these materials is less than that of the single layer counterparts. Finally, a transverse electric field is applied to the doped bilayers and it is found that the bandgap is inversely proportional to the electric field strength in contrast to what has been observed in the case of pristine bilayers. Carrier effective masses were calculated and in general the effective masses of electrons and holes are found to be similar.

Kaplan, D.; Swaminathan, V.; Recine, G.; Balu, R.; Karna, S.

2013-05-01

44

Neue Elemente der Bedeckungsveraenderlichen GSC 6281-246 (Brb V149) und GSC 2161-1310 (Brh V155)  

NASA Astrophysics Data System (ADS)

CCD observations and ASAS-3 data of GSC 6281-246 (Brh V149) and GSC 2161-1310 (Brh V155) lead to the following updated elements and types of variability: GSC 6281-246: HJD(MinI)=2453236.358(1) + E* 2.498117(1), type: EA; GSC 2161-1310: HJD (MinI)=2455063.452(3)+ E* 0.746624(2), type: EB

Bernhard, Klaus; Frank, Peter

2010-01-01

45

Hydrogen. Stopping powers and ranges in all elements. [10 keV to 20 MeV (per amu); book  

Microsoft Academic Search

Absolute experimental energy-loss data for hydrogen are presented over the energy range E\\/amu = 10 keV to 20 MeV. Data were fitted to analytical functions, the parameters of which are given together with the experimental data. An attempt was made to interpolate the fitting parameters to elements for which there are no experimental data. Fitted stopping powers were integrated to

H. H. Andersen; J. F. Ziegler

1977-01-01

46

Low Atomic Energy Levels for Elements of the Oxygen Group  

Microsoft Academic Search

FROM spectral theory it is known that the lowest energy states for atoms of the oxygen group form a stable triad designated as 3P012. Next higher to these is a metastable state 1D2 and next to that again a metastable state 1S0 For oxygen atoms the state 3P1 expressed in frequency units is known to be 67 cm.-1 higher than

J. C. McLennan; M. F. Crawford

1929-01-01

47

Fish retroposons related to the Penelope element of Drosophila virilis define a new group of retrotransposable elements.  

PubMed

Poseidon and Neptune are two ancient lineages of retroposons related to the Penelope element from Drosophila virilis. They have been identified in various teleost fish species, including the medakafish (Oryzias latipes), and the pufferfishes Fugu rubripes and Tetraodon nigroviridis, whose genomes are currently being sequenced. Some of these elements are highly reiterated in fish genomes. Penelope-related elements were also identified in blood fluke, shrimp, sea urchin, cichlid fish and frog, showing that they are widespread in animals. Penelope-related retroposons were not detected among sequences from the Drosophila melanogaster and human genome projects, suggesting that they have been lost from certain animal lineages. A sequence encoding a putative Uri (also called GIY-YIG) endonuclease domain was detected downstream from the gene for reverse transcriptase. To the best of our knowledge, this type of endonuclease sequence has previously been identified in group I introns and in genes for prokaryotic excinucleases but not in retrotransposable elements. Penelope-related elements are frequently truncated at their 5' ends and can also be flanked by long terminal repeat-like structures. Phylogenetic analysis of the reverse transcriptase domain failed to assign Penelope-related retroposons to one of the major groups of retroelements. Overall, therefore, the evidence strongly suggests that these sequences represent a new group of retrotransposable elements. PMID:11459192

Volff, J N; Hornung, U; Schartl, M

2001-06-01

48

Elemental abundance analyses with DAO spectrograms: XXXII. HR 6455 (A3 III), ? Aqr (A3 V), ? Lep (F2 V), and 1 Boo (A1 V)  

NASA Astrophysics Data System (ADS)

We examine the sharp-lined stars HR 6455 (A3 III, v sin i = 8.7 km s-1) and ? Lep (F2 V, v sin i = 13.5 km s-1) as well as ? Aqr (A3 V, v sin i = 81 km s-1) and 1 Boo (A1 V, v sin i = 59 km s-1) to increase the number consistently analyzed A and F stars using high dispersion and high S/N (?200) spectrograms obtained with CCD detectors at the long Coudé camera of the 1.22-m telescope of the Dominion Astrophysical Observatory. Such studies contribute to understanding systematic abundance differences between normal and non-magnetic main-sequence band chemically peculiar A and early F stars. LTE fine analyses of HR 6455, ? Aqr, and 1 Boo using Kurucz's ATLAS suite programs show the same general elemental abundance trends with differences in the metal richness. Light and iron-peak element abundances are generally solar or overabundant while heavy element and rare earth element abundances are overabundant. HR 6455 is an evolved Am star while ? Aqr and 1 Boo show the phenomenon to different extents. Most derived abundances of ? Lep are solar. Table 3 is available at the CDS via http://cdsarc.u-strasbg.fr/cgi-bin/qcat?J/AN/332/681

Yüce, K.; Adelman, S. J.; Gulliver, A. F.; Hill, G.

2011-08-01

49

Calculations of stopping powers of 100 eV30 keV electrons in 31 elemental solids  

Microsoft Academic Search

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

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

2008-01-01

50

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

Microsoft Academic Search

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

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

2008-01-01

51

Transposition of hAT elements links transposable elements and V(D)J recombination  

Microsoft Academic Search

Transposons are DNA sequences that encode functions that promote their movement to new locations in the genome. If unregulated, such movement could potentially insert additional DNA into genes, thereby disrupting gene expression and compromising an organism's viability. Transposable elements are classified by their transposition mechanisms and by the transposases that mediate their movement. The mechanism of movement of the eukaryotic

Liqin Zhou; Rupak Mitra; Peter W. Atkinson; Alison Burgess Hickman; Fred Dyda; Nancy L. Craig

2004-01-01

52

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

53

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

54

Quantum-chemical calculations of triphenyl compounds of the VB group elements  

Microsoft Academic Search

Various approximations of the MO-LCAO method were used to study the effect of the electronic structure upon the spectra of triphenyl derivatives of the VB group elements. Both the chemical and optical properties of aromatic derivatives of these elements in their trivalent states have to be interpreted on the basis of the overall influence of electronic effects operating in opposite

N. P. Borisova; L. N. Petrov

1972-01-01

55

Adhesion and Friction Behavior of Group 4 Elements Germanium, Silicon, Tin, and Lead.  

National Technical Information Service (NTIS)

Adhesion and friction studies were conducted with thin films of the group IV elements silicon, germanium, tin, and lead ion plated on the nickel (011) substrate. The mating surface was gold (111). Contacts were made for the elements in the clean state and...

D. H. Buckley

1975-01-01

56

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

57

Analyses of platinum group elements in mosses as indicators of road traffic emissions in Austria  

Microsoft Academic Search

The concentrations of platinum group elements (PGE; platinum, palladium, rhodium) and 17 other elements in mosses growing at 32 sampling sites along 12 roads in Austria were analysed. The study included passive monitoring of naturally growing mosses with an experimental design using mosses samples exposed in a tunnel experiment. PGEs (Pt, Pd, Rh) were analysed by ICP-MS (ELAN DRC II,

Harald G. Zechmeister; Harald Hagendorfer; Daniela Hohenwallner; Andrea Hanus-Illnar; Alarich Riss

2006-01-01

58

Deposition of platinum group elements and polycyclic aromatic hydrocarbons on ryegrass exposed to vehicular traffic  

Microsoft Academic Search

Along highways, platinum group elements (PGE: Pt, Pd and Rh) and polycyclic aromatic hydrocarbons (PAHs) produced by the vehicle\\u000a traffic can be deposited on grass and soil, leading to a risk of contamination through the food chain via farm animals. We\\u000a studied the deposition of platinum group elements and polycyclic aromatic hydrocarbons on ryegrass pots exposed along a highway\\u000a with

Abdourahamane Tankari Dan-Badjo; Cécile Ducoulombier-Crépineau; Claire Soligot; Cyril Feidt; Guido Rychen

2007-01-01

59

A Family of Finite Simple Groups Which Are 2Recognizable by Their Elements Order  

Microsoft Academic Search

Let G be a finite group and ?(G) the set of all orders of elements in G. Denote by h(?(G)) the number of isomorphism classes of finite groups H satisfying ?(H) = ?(G), and put h(G) = h(?(G)). A group G is called k-recognizable if h(G) = k < ? , otherwise G is called non-recognizable. In the present article we will show that the simple groups PSL(3, q),

A. R. Moghaddamfar; M. R. Darafsheh

2004-01-01

60

19 Cl NQR study of the fluorine effect of the aryl substituent on the element-chlorine bond in compounds of subgroup V and VI elements  

Microsoft Academic Search

UDC 541.49 Due to the introduction of fluorine atoms into the benzene ring, the accepting effect of the pentafluorophenyl group is higher than that of the phenyl one, this increases the electronegativity of the element of the functional group directly bonded to the group. In compounds in which the given element of the functional group is directly bonded to the

O. Kh. Poleshchuk; G. G. Furin; I. Latoszinska

1997-01-01

61

Erosion of volatile elemental condensed gases by keV electron and light-ion bombardment.  

National Technical Information Service (NTIS)

Erosion of the most volatile elemental gases by keV electron and light-ion bombardment has been studied at the experimental setup at Risoe. The present work includes frozen neon, argon, krypton, nitrogen, oxygen and three hydrogen isotopes, deuterium, hyd...

J. Schou

1991-01-01

62

Unbounded elements affiliated with C *-algebras and non-compact quantum groups  

Microsoft Academic Search

The affiliation relation that allows to include unbounded elements (operators) into theC*-algebra framework is introduced, investigated and applied to the quantum group theory. The quantum deformation of (the two-fold covering of) the group of motions of Euclidean plane is constructed. A remarkable radius quantization is discovered. It is also shown that the quantumSU(1, 1) group does not exist on theC*-algebra

S. L. Woronowicz

1991-01-01

63

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.

?kstad, Ole Andreas; Tourasse, Nicolas J.; Stabell, Fredrik B.; Sundfaer, Cathrine K.; Egge-Jacobsen, Wolfgang; Ris?en, Per Arne; Read, Timothy D.; Kolst?, Anne-Brit

2004-01-01

64

Configuration interaction matrix elements. I. Algebraic approach to the relationship between unitary group generators and permutations  

Microsoft Academic Search

Matrix elements of unitary group generators between spin-adapted antisymmetric states are shown to be proportional to spin matrix elements of so-called line-up permutations. The proportionality factor is given explicitly as a simple function of the orbital occupation numbers. If one bases the theory on ordered orbital products, the line-up permutations are given a priori. The final formulas have a very

P. E. S. Wormer; J. Paldus

1979-01-01

65

Configuration interaction matrix elements. II. Graphical approach to the relationship between unitary group generators and permutations  

Microsoft Academic Search

The explicit expressions for the matrix elements of unitary group generators between geminally antisymmetric spin-adapted N-electron configurations in terms of the orbital occupancies and spin factors, given as spin function matrix elements of appropriate orbital permutations, are derived by use of the many-body time-independent diagrammatic techniques. It is also shown how this approach can be conveniently combined with graphical methods

J. Paldus; P. E. S. Wormer

1979-01-01

66

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

SciTech Connect

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

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

1983-01-01

67

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

USGS Publications Warehouse

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

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

2011-01-01

68

Computation of oscillator strengths by a semi-empirical method for some elements of the iron-group and their solar photospheric abundance  

Microsoft Academic Search

Oscillator strengths calculated by the STF method for selected transitions of V i and Co i have permitted to deduce, from an LTE study of weak lines, photospheric abundances in agreement with those obtained from carbonaceous chondrites. A summary of results is also presented for all the iron-group elements.

E. Biemont

1978-01-01

69

The measurement of elemental abundances above 10 exp 15 eV at a lunar base  

NASA Astrophysics Data System (ADS)

At about 10 exp 15 eV the slope of the energy spectrum of cosmic rays becomes significantly steeper than at lower energies. The measurement of relative elemental abundances at these energies is expected to provide a means to resolve the origin of this feature and greatly contribute to the understanding of the sources of cosmic rays. A moon-based detector for making well-resolved elemental measurements at these energies is described using hadronic calorimetry. This detector is particularly well suited for a site on the lunar surface because there is no overlying layer of atmosphere and the large mass required can be provided by the lunar regolith.

Swordy, S. P.

1990-03-01

70

Distribution characteristics of gold and other trace elements in the Proterozoic Lengjiaxi Group, northeastern Hunan Province  

Microsoft Academic Search

Systematic geochemical studies of the Proterozoic Lengjiaxi Group in northeastern Hunan Province suggest that the Lengjiaxi\\u000a Group is a Au-As-Sb-W association-type Au-bearing turbidite formation. The contents of Au, As, Sb, W, Cr, Mn, Pb and Zn in\\u000a the turbidite formation are more than two times as high as the average contents of trace elements in the upper continental\\u000a crust. The

Yingjun Liu; Junfeng Ji; Weidong Cui; Chengyuan Sun

1992-01-01

71

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

Microsoft Academic Search

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

Maurice Robert Kibler

2004-01-01

72

Three dimensional heterogeneous finite element method for static multi-group neutron diffusion  

Microsoft Academic Search

Because current full-core neutronic-calculations use two-group neutron diffusion and rely on homogenizing fuel assemblies, reconstructing pin powers from such a calculation is an elaborate and not very accurate process; one which becomes more difficult with increased core heterogeneity. A three-dimensional Heterogeneous Finite Element Method (HFEM) is developed to address the limitations of current methods by offering fine-group energy representation and

Elif Can Aydogdu

2010-01-01

73

Radiochemical Separation of Group 5 Elements. Model Experiments for Investigation of Dubnium Chemical Behaviour  

SciTech Connect

Chemical behaviour of group 5 elements in the aqueous hydrofluoric acid solutions was studied. The radiochemical method for the cation exchange separation of Nb (Pa) and Ta from Zr, Hf and lanthanides is presented. The developed scheme allows excluding of the presence of SF heavy actinides in fractions of separated elements. On the basis of the data of the present work, it is possible to suggest the following order of the stability of the fluoride complexes of group 4 and 5 elements: Nb {approx_equal} Pa > Zr > Hf > Ta. The order of the complex formation is in agreement with theoretical predictions. This analytical procedure can be used in future heavy nuclei synthesis experiments for the separation of dubnium (Db) from other reactions products and for its chemical identification.

Tereshatov, E. E.; Bozhikov, G. A.; Aksenov, N. V.; Starodub, G. Ya.; Vostokin, G. K.; Shishkin, S. V.; Dmitriev, S. N. [Flerov Laboratory of Nuclear Reactions (FLNR), JINR, Dubna RU-141980 (Russian Federation); Bruchertseifer, H.; Gaeggeler, H. W. [Paul Scherrer Institute (PSI), Villigen CH-5232 (Switzerland)

2007-05-22

74

Heat capacity anharmonicity in elemental vanadium and V93Co7  

Microsoft Academic Search

The specific heats of elemental vanadium and V93Co7 with body-centered cubic crystal structure were measured by differential scanning calorimetry from room-temperature to 1400 °C. The results were compared to the harmonic phonon contribution, the electronic contribution, and the expansion against the bulk modulus contribution to the total heat capacity. The harmonic phonon contribution was obtained from the phonon densities-of-states, measured

Jorge Munoz; Olivier Delaire; Brent Fultz

2006-01-01

75

Finite element simulation of conventional and high speed machining of Ti6Al4V alloy  

Microsoft Academic Search

Titanium alloys are known as difficult-to-machine materials, especially at higher cutting speeds, due to their several inherent properties and their high reactivity with cutting tools, which present a low thermal conductivity. In this paper a finite element analysis (FEA) of machining of TiAl6V4 both for conventional and high speed cutting regimes is presented. In particular, cutting force, chip morphology and

Domenico Umbrello

2008-01-01

76

Chemical Vapor Deposition of Group IVB, VB, and VIB Elements; a Literature Review.  

National Technical Information Service (NTIS)

The Bureau of Mines reviewed the chemical vapor deposition (CVD) literature of the group IVB, VB, and VIB elements. This review was used in the Bureau's research to provide erosion-, abrasion-, and corrosion-resistant coatings for valve components used in...

H. O. McDonald J. B. Stephenson

1979-01-01

77

Chemical vapor deposition of group IVB, VB, and VIB elements; a literature review. Information circular  

Microsoft Academic Search

The Bureau of Mines reviewed the chemical vapor deposition (CVD) literature of the group IVB, VB, and VIB elements. This review was used in the Bureau's research to provide erosion-, abrasion-, and corrosion-resistant coatings for valve components used in coal gasification units. This report attempts to bring together the many CVD references that have been published since 1966. Each of

H. O. McDonald; J. B. Stephenson

1979-01-01

78

A folding control element for tertiary collapse of a group II intron ribozyme  

Microsoft Academic Search

Ribozymes derived from the group II intron ai5? collapse to a compact intermediate, folding to the native state through a slow, direct pathway that is unperturbed by kinetic traps. Molecular collapse of ribozyme D135 requires high magnesium concentrations and is thought to involve a structural element in domain 1 (D1). We used nucleotide analog interference mapping, in combination with nondenaturing

Christina Waldsich; Anna Marie Pyle

2006-01-01

79

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

80

Kinetic determination of rare elements of the platinum group in natural materials  

SciTech Connect

Methods for kinetic determination of osmium, ruthenium, and iridium have been developed. The preparation of samples of different composition, namely, sulfide, oxide, silicate, biogeochemical, and natural waters, is described. Schemes are given for analysis of natural materials for concentration of rare elements of the platinum group.

Romanovskaya, L.E.; Khomutova, E.G.; Rysev, A.P. [M.V. Lomonosov Moscow State Academy of Fine Chemical Engineering (Russian Federation)

1995-02-01

81

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

82

CO2 Methanation Catalysts Prepared from Amorphous Ni-Valve Metal Alloys Containing Platinum Group Elements.  

National Technical Information Service (NTIS)

The amorphous Ni-valve metal (Ti, Zr, Nb, and Ta) alloys containing a few at percent of platinum group elements were activated by immersion into hydrofluoric acid and used for hydrogenation of carbon dioxide at 100 to 300 C. This surface activation led to...

K. Wakuda H. Habazaki A. Kawashima K. Asami K. Hashimoto

1993-01-01

83

Graph coloration and group theory in dynamic analysis of symmetric finite element models  

Microsoft Academic Search

In this article the idea of graph coloration from spectral graph theory is employed in conjunction with group theoretical concepts for efficient eigensolution of adjacency matrices of graphs. The application of the method is extended to free vibration analysis of symmetric finite element problems, constructing a graph model of the problem in a local symmetry adapted coordinate system.

A. Kaveh; H. Fazli

2007-01-01

84

Abundance of Elements beyond the Iron Group in Cool DO White Dwarfs  

Microsoft Academic Search

We report the presence of elements beyond the iron group in the atmospheres of the cool DO white dwarfs HD 149499 B and HZ 21. Photospheric lines of germanium (Z=32), arsenic (33), selenium (34), tin (50), tellurium (52), iodine (53), and perhaps bromine (35) are observed in ultraviolet spectra of HD 149499 B obtained with the Far Ultraviolet Spectroscopic Explorer

P. Chayer; S. Vennes; J. Dupuis; J. W. Kruk

2005-01-01

85

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

86

A Novel Integrative Conjugative Element Mediates Genetic Transfer from Group G Streptococcus to Other  Hemolytic Streptococci  

Microsoft Academic Search

Lateral gene transfer is a significant contributor to the ongoing evolution of many bacterial pathogens, including -hemolytic streptococci. Here we provide the first characterization of a novel integrative conjugative element (ICE), ICESde3396, from Streptococcus dysgalactiae subsp. equisimilis (group G streptococcus (GGS)), a bacterium commonly found in the throat and skin of humans. ICESde3396 is 64 kb in size and encodes

Mark R. Davies; Josephine Shera; Gary H. Van Domselaar; Kadaba S. Sriprakash; David J. McMillan

2009-01-01

87

Response to the report of the transfermium working group ``discovery of the transfermium elements''  

Microsoft Academic Search

The report of the Transfermium Working Group (TWG) ``Discovery of the Transfermium Elements'' is riddled with errors of omission and commission. Many relevant references and much relevant data were omitted as a result of the selective use of references and data. There were only two members representing the IUPAC on the TWG (and these were not nuclear chemists) while there

A. Ghiorso; G. T. Seaborg

1993-01-01

88

Direct gauging of the Poincare group V. Group scaling, classical gauge theory, and gravitational corrections  

SciTech Connect

Homogeneous scaling of the group space of the Poincare group, P/sub 10/, is shown to induce scalings of all geometric quantities associated with the local action of P/sub 10/. The field equations for both the translation and the Lorentz rotation compensating fields reduce to O(1) equations if the scaling parameter is set equal to the general relativistic gravitational coupling constant 8..pi..Gc/sup -4/. Standard expansions of all field variables in power series in the scaling parameter give the following results. The zeroth-order field equations are exactly the classical field equations for matter fields on Minkowski space subject to local action of an internal symmetry group (classical gauge theory). The expansion process is shown to break P/sub 10/-gauge covariance of the theory, and hence solving the zeroth-order field equations imposes an implicit system of P/sub 10/-gauge conditions. Explicit systems of field equations are obtained for the first- and higher-order approximations. The first-order translation field equations are driven by the momentum-energy tensor of the matter and internal compensating fields in the zeroth order (classical gauge theory), while the first-order Lorentz rotation field equations are driven by the spin currents of the same classical gauge theory. Field equations for the first-order gravitational corrections to the matter fields and the gauge fields for the internal symmetry group are obtained. Direct Poincare gauge theory is thus shown to satisfy the first two of the three-part acid test of any unified field theory. Satisfaction of the third part of the test, at least for finite neighborhoods, seems probable.

Edelen, D.G.B.

1986-07-01

89

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 CaFeSi2O6 contents (15-45 mol%) to aegirine with < 25 mol% of CaMgSi2O6 and a negligible proportion of CaFeSi2O6. 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

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

DFT Study of Structural and Electronic Properties of Endohedral Complexes of Group V Atoms with C60  

NASA Astrophysics Data System (ADS)

The structural and electronic properties of endohedral fullerenes formed by encapsulation of each of the group V elements inside the buckminsterfullerene cage have been investigated. The calculations reveal that all these species are thermodynamically stable, though the formation of Sb@C60 and Bi@C60 is slightly endothermic. The central atom preserves its electronic configuration and the quartet state. The energy gap and energy levels are perturbed by the inclusion of a foreign atom. The band gap of Sb@C60 and Bi@C60 is found to be significantly smaller than pristine C60, suggesting the reactivity of these complexes.

Pahuja, Akshu; Srivastava, Sunita

2013-10-01

92

Complex formation of elements of the third group of the periodic system with chromazurol s  

SciTech Connect

An attempt is made to establish the composition and spectrophotometric characteristics of colored complexes of elements of the third group of the periodic system, produced with chromazurol S purified according to the procedure described. For a comparison of data on complexes of various elements with this reagent the authors used published results of an investigation of the complex formation of aluminium and those results they themselves obtained. The complex formation of aluminum, gallium, indium, scandium, yttrium, lanthanum, and cerium (III) were studied with the chromazurol S. The mechanism of the reaction of aluminum, gallium, scandium, and yttrium with chromazurol S was examined.

Tikhonov, V.N.

1985-03-01

93

Laser photolysis and CIDEP studies of the formation of phenyl-substituted group 4B element (silicon, germanium, and tin)-centered radicals in direct photoejection of the group 4B element-centered anions  

Microsoft Academic Search

Phenyl-substituted group 4B element-centered radicals generated by the direct photoejection from the group 4B element-centered anions were observed by laser photolysis at room temperature. In order to clarify the mechanism of this process, CIDEP study of the photolysis of the group 4B element-centered anions was carried out at 77 and 4.2 K. From the emissive patterns observed for the germyl

Kunio Mochida; Masanobu Wakasa; Yoshio Sakaguchi; Hisaharu Hayashi

1987-01-01

94

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

95

Spontaneous sulfur dioxide activation by Group V metal (V, Nb, Ta) atoms in excess argon at cryogenic temperatures.  

PubMed

Reactions of laser-ablated V, Nb and Ta atoms with SO2 in excess argon during condensation gave new absorptions in the M=O stretching region, which were assigned to metal sulfide oxides SMO2 and anions SMO2(-) (M = V, Nb, Ta). The metal oxide complex OV(?(2)-SO) was also identified through the V=O and the characteristic side-on coordinated S-O stretching modes. The assignments of major vibrational modes were confirmed by appropriate S(18)O2 and (34)SO2 isotopic shifts, and density functional frequency calculations. DFT calculations were employed to study the behavior of reactions of Group V bare metal atoms with SO2, and a representative profile was derived which not only showed the preferred coordinating fashion of metal atoms but also tracked the path of S-O bond activation. The ?(2)-O,O' bridge coordinated complexes are preferred with energy decreases of ca. 50 kcal mol(-1) for all three metals, which facilitate the activation of two S-O bonds in succession and finally direct the reaction to the most stable molecules SMO2 (M = V, Nb, Ta) along the potential energy surface (PES). Finally the SMO2 molecules capture electrons to give anions SMO2(-) with about 3.6 eV electron affinities based on DFT calculations. PMID:23677396

Liu, Xing; Wang, Xuefeng; Wang, Qiang; Andrews, Lester

2013-06-28

96

Investigation of Organic Carbon and Iron Group Elements in Bituminous Rocks  

Microsoft Academic Search

In this study, geochemical and biogeochemical features of the organic-rich bituminous shales of the Bolu-Mengen area were investigated. The deposition levels of carbon and iron group metals (Mn, Ni, V, Cr, Co, Ti, Sc) within the bituminous shales and their correlation were also examined. Samples studied contain high amount of organic carbon (Corg), and they have Type I and Type

Saday Aliyev; Ali Sari; ?ükrü Koç

2006-01-01

97

Quality evaluation of value sets from cancer study common data elements using the UMLS semantic groups  

PubMed Central

Objective The objective of this study is to develop an approach to evaluate the quality of terminological annotations on the value set (ie, enumerated value domain) components of the common data elements (CDEs) in the context of clinical research using both unified medical language system (UMLS) semantic types and groups. Materials and methods The CDEs of the National Cancer Institute (NCI) Cancer Data Standards Repository, the NCI Thesaurus (NCIt) concepts and the UMLS semantic network were integrated using a semantic web-based framework for a SPARQL-enabled evaluation. First, the set of CDE-permissible values with corresponding meanings in external controlled terminologies were isolated. The corresponding value meanings were then evaluated against their NCI- or UMLS-generated semantic network mapping to determine whether all of the meanings fell within the same semantic group. Results Of the enumerated CDEs in the Cancer Data Standards Repository, 3093 (26.2%) had elements drawn from more than one UMLS semantic group. A random sample (n=100) of this set of elements indicated that 17% of them were likely to have been misclassified. Discussion The use of existing semantic web tools can support a high-throughput mechanism for evaluating the quality of large CDE collections. This study demonstrates that the involvement of multiple semantic groups in an enumerated value domain of a CDE is an effective anchor to trigger an auditing point for quality evaluation activities. Conclusion This approach produces a useful quality assurance mechanism for a clinical study CDE repository.

Solbrig, Harold R; Chute, Christopher G

2012-01-01

98

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

NASA Astrophysics Data System (ADS)

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, the most electropositive element of all elements, to element 119, with its ? value approaching that of Na. Due to the largest relativistic effects on the 8s(119) AO in group 1, bonding in (119)2 appears to be stronger than that of K2, while bonding in 119Au should be the weakest out of all group-1 MAu. Using calculated dissociation energies of M2, sublimation enthalpies, ?Hsub, of Fr of 77 kJ/mol and element 119 of 94 kJ/mol were estimated using a linear correlation between these quantities in the chemical group. Using the M-Au binding energies, the adsorption enthalpies, -?Hads, of 106 kJ/mol on gold, 76 kJ/mol on platinum, and 63 kJ/mol on silver were estimated for element 119 via a correlation with known ?Hads in the chemical group. These moderate ?Hads values are indicative of a possibility of chromatography adsorption studies of element 119 on the noble metal surfaces.

Pershina, V.; Borschevsky, A.; Anton, J.

2012-02-01

99

Four-group stabilized zoom lens design of two focal-length-variable elements.  

PubMed

We present a theoretical method for analyzing the first-order optics of stabilized zoom lenses with two focal-length-variable elements. The zoom equations are established through the use of the Gaussian brackets method. This is done because the optical power of the focal-length-variable elements varies during the zooming process. The first and second derivatives and the Hessian matrix of the zoom equations with respect to the Gaussian parameters are determined using the equations. These parameters could represent the sensitivity of the zoom ratio of the system to changes in the corresponding system variables. We select the initial values of these system variables, i.e. the magnification of the focal-length-variable element and the structure parameters of the fixed lens group, to be close to the steepest gradient direction. Here the sensitivity of the system focal length is high with respect to variations in the zoom variables. This process leads to an increase in the zoom ratio of the zoom system. The results show successful four-group stabilized zoom lens designs with 2:1 and 5:1 zoom ratios, using two deformable mirrors as focal-length-variable elements. This system, with the inherent characteristics of a steepest gradient, could miniaturize zoom systems. PMID:23546157

Hao, Qun; Cheng, Xuemin; Du, Ke

2013-03-25

100

Formation of Ni–Cu–Platinum Group Element sulfide mineralization in the Sudbury Impact Melt Sheet  

Microsoft Academic Search

Summary The Ni–Cu–Platinum Group Element (PGE) sulfide deposits of the Sudbury Structure have provided a major portion of the world’s total nickel production and their host rocks have been the subject of numerous research studies, yet a number of perplexing problems remain to be solved. On the one hand, studies seeking to explain the formation of the Sudbury Structure have

R. R. Keays; P. C. Lightfoot

2004-01-01

101

Particle–water interactions of platinum group elements under estuarine conditions  

Microsoft Academic Search

Particle–water interactions of selected platinum group elements (PGE) have been studied as a function of pH (between 5 and 10), salinity, and concentrations of Cl? and Ca2+. Rhodium(III), Pd(II) and Pt(IV) were added to water samples and sediment suspensions and, following a period of equilibration and subsequent phase separation, filtrates and HCl-digested filters were analysed by ICP-MS. PGE removal from

Andrew Turner

2007-01-01

102

Binary covalent crystals of group IVa elements: Interatomic interaction and properties  

Microsoft Academic Search

Correlations of potential parameters with the atomic weight are used to determine parameters of the interatomic interaction\\u000a potential for sphalerite-structured AB binary crystals composed of group IVa elements. It is shown that the parameters for\\u000a elastic (reversible) deformation differ from those for plastic (irreversible) deformation capable of breaking covalent bonds.\\u000a A calculational procedure is proposed for evaluating the properties of

M. N. Magomedov

2010-01-01

103

Hall-Higman-type theorems for semisimple elements of finite classical groups  

Microsoft Academic Search

We prove an analogue of the celebrated Hall-Higman theorem, which gives a\\u000alower bound for the degree of the minimal polynomial of any semisimple element\\u000aof prime power order $p^{a}$ of a finite classical group in any nontrivial\\u000airreducible cross characteristic representation. With a few explicit\\u000aexceptions, this degree is at least $p^{a-1}(p-1)$.

Pham Huu Tiep; A. E. ZALESSKIùI

2008-01-01

104

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

Microsoft Academic Search

This paper is concerned with the application of the group SO(4,2)xSU(2) to\\u000athe periodic table of chemical elements. It is shown how the Madelung rule of\\u000athe atomic shell model can be used for setting up a periodic table that can be\\u000afurther rationalized via the group SO(4,2)xSU(2) and some of its subgroups.\\u000aQualitative results are obtained from the table

Maurice Robert Kibler

2004-01-01

105

Quintuple bond reactivity toward group 16 and 17 elements: addition vs insertion.  

PubMed

The low valent, coordinatively unsaturated, and formally quintuply bonded bimetallic aminopyridinato chromium complex 1 was investigated regarding its reactivity toward group 16 and 17 elements. Reaction of 1 with O(2) yielded a dimeric Cr oxo complex 2, a compound with a high formal oxidation state carrying both bridging and terminal oxo ligands. Reactions with the higher homologues of the group lead to the formation of dimeric Cr(II) complexes in which E(2)(2-) ligands were formed [E = S (3), Se (4), and Te (5)]. Here the quintuply bonded dichromium unit formally undergoes an addition reaction. Reaction of 1 with the homo diatomic molecules of the group 17 elements leads to products in which the Cr-Cr quintuple bond is inserted into the corresponding X(2) molecule [X = Cl (6), Br (7), and I (8)]. Complex 1 was also found to insert into the S-S and Se-Se bonds of 1,2-diphenyldisulfane or the corresponding selenium compound (complexes 9 and 10, respectively). All the compounds have been characterized by NMR and elemental analysis. Additionally, eight of the complexes have been characterized by X-ray analysis. The bimetallic Cr(II) complexes feature metal-metal distances between 1.8369(18) and 1.918(12) Å. PMID:23240786

Tamne, Emmanuel Sobgwi; Noor, Awal; Qayyum, Sadaf; Bauer, Tobias; Kempe, Rhett

2012-12-14

106

Energy Spectrum and Elemental Composition in the PeV Region  

NASA Astrophysics Data System (ADS)

One of the main aims of KASCADE is the determination of flux spectra for different primary cosmic ray mass groups to disentangle the knee feature. The field detector array of the KASCADE experiment measures the electron and muon component of extensive air showers in the knee region with high precision. On the basis of these measured data corresponding two-dimensional shower size spectra are investigated. On the arbitrary assumption that the chemical composition consists of five primary mass groups the size distributions are deconvoluted to reconstruct the energy spectra of the groups in the energy range between 1015 eV and 1017 eV. The energy spectrum results in a knee-like bending and a steep ening above the knee. The top ology of the individual knee positions suggests a rigidity dependence.

Roth, M.; Ulrich, H.; Antoni, T.; Apel, W. D.; Badea, F.; Bekk, K.; Bercuci, A.; Blümer, H.; Bozdog, H.; Brancus, I. M.; Büttner, C.; Chilingarian, A.; Daumiller, K.; Doll, P.; Engel, R.; Engler, J.; Feßler, F.; Gils, H. J.; Glasstetter, R.; Haungs, A.; Heck, D.; Hörandel, J. R.; Iwan, A.; Kampert, K. H.; Klages, H. O.; Maier, G.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Müller, M.; Obenland, R.; Oehlschläger, J.; Ostapchenko, S.; Petcu, M.; Rebel, H.; Risse, M.; Schatz, G.; Schieler, H.; Scholz, J.; Thouw, T.; van Buren, J.; Vardanyan, A.; Weindl, A.; Wochele, J.; Zabierowski, J.

2003-07-01

107

One-Dimensional Nanostructures and Devices of II-V Group Semiconductors  

NASA Astrophysics Data System (ADS)

The II-V group semiconductors, with narrow band gaps, are important materials with many applications in infrared detectors, lasers, solar cells, ultrasonic multipliers, and Hall generators. Since the first report on trumpet-like Zn3P2 nanowires, one-dimensional (1-D) nanostructures of II-V group semiconductors have attracted great research attention recently because these special 1-D nanostructures may find applications in fabricating new electronic and optoelectronic nanoscale devices. This article covers the 1-D II-V semiconducting nanostructures that have been synthesized till now, focusing on nanotubes, nanowires, nanobelts, and special nanostructures like heterostructured nanowires. Novel electronic and optoelectronic devices built on 1-D II-V semiconducting nanostructures will also be discussed, which include metal-insulator-semiconductor field-effect transistors, metal-semiconductor field-effect transistors, and p- n heterojunction photodiode. We intent to provide the readers a brief account of these exciting research activities.

Shen, Guozhen; Chen, Di

2009-08-01

108

One-Dimensional Nanostructures and Devices of II-V Group Semiconductors.  

PubMed

The II-V group semiconductors, with narrow band gaps, are important materials with many applications in infrared detectors, lasers, solar cells, ultrasonic multipliers, and Hall generators. Since the first report on trumpet-like Zn(3)P(2) nanowires, one-dimensional (1-D) nanostructures of II-V group semiconductors have attracted great research attention recently because these special 1-D nanostructures may find applications in fabricating new electronic and optoelectronic nanoscale devices. This article covers the 1-D II-V semiconducting nanostructures that have been synthesized till now, focusing on nanotubes, nanowires, nanobelts, and special nanostructures like heterostructured nanowires. Novel electronic and optoelectronic devices built on 1-D II-V semiconducting nanostructures will also be discussed, which include metal-insulator-semiconductor field-effect transistors, metal-semiconductor field-effect transistors, and p-n heterojunction photodiode. We intent to provide the readers a brief account of these exciting research activities. PMID:20596452

Shen, Guozhen; Chen, Di

2009-05-15

109

Response to the report of the transfermium working group ``discovery of the transfermium elements''  

NASA Astrophysics Data System (ADS)

The report of the Transfermium Working Group (TWG) ``Discovery of the Transfermium Elements'' is riddled with errors of omission and commission. Many relevant references and much relevant data were omitted as a result of the selective use of references and data. There were only two members representing the IUPAC on the TWG (and these were not nuclear chemists) while there were seven members representing the IUPAP. Much of the experimental evidence is of a basically chemical nature and its proper evaluation would have benefited from the presence of more nuclear chemists on the TWG. Especially grievous is the rejection of the Berkeley claim to the 1955 discovery of element 101 which was based on a clear-cut chemical identification. Our most serious quarrel with the TWG report is their treatment of the discovery of element 104. It is clearly a waste of time and effort to reopen the cases of elements 102 and 103, which were discovered more than 30 years ago with the approval of the suggested names by the IUPAC according to the standards of that era.

Ghiorso, A.; Seaborg, G. T.

110

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

...evaluation criteria for vessels carrying group V petroleum oil as a primary cargo. 155...evaluation criteria for vessels carrying group V petroleum oil as a primary cargo. (a...and operators of vessels that carry group V petroleum oil as a primary cargo must...

2013-07-01

111

Design of large aperture four group elements mid-wave infrared zoom lens  

NASA Astrophysics Data System (ADS)

Zoom lens with variable focal length is well fit for researching objectives far and near. Design of zoom lens working at mid-wave infrared wavelength (7.7-10.3_m) and its view field 10 degrees is presented. Determination of the initial configuration of the variable and the compensate groups are discussed according to the mechanism compensate curves. The compensate group is determined with positive power. Its focal length changes during a large scope, which is from 300mm to 100mm. And the corresponding F number variables from 3.75 to 1.25. So the residual aberration needs to be carefully corrected. The optimized zoom lens is composed of four group elements, and its performance reaches diffraction limited at each focal position.

Ji, Yiqun; Shi, Rongbao; He, Hucheng; Shen, Weimin

2012-10-01

112

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

113

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

Microsoft Academic Search

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

H. O. McDonald; J. B. Stephenson

1983-01-01

114

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

115

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

Microsoft Academic Search

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

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

2011-01-01

116

Trace Element Analysis with PIXE Using Trombay 5.5 MeV Van de Graaff Accelerator.  

National Technical Information Service (NTIS)

The work on trace element analysis using proton induced X-ray emission technique (PIXE) with the proton beam from 5.5 MeV Van de Graaff accelerator at Trombay, is described. The experimental set up consisted of an indigeneously built 220 eV resolution Si(...

R. Govil S. K. Kataria S. S. Kapoor Madan Lal D. M. Nadkarni

1980-01-01

117

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

118

Nature of the phase transition in gallium arsenide doped with group-VI elements  

SciTech Connect

The authors measure the molar heat capacity on series of gallium arsenide single crystals doped with tellurium and selenium and grown by the Czochralski method from beneath a flux. A conductive calorimeter was provided with anisotropic bismuth thermocouples for converting the normal thermal flux to a tangential electromagnetic field. Antimony was used as the standard. The relative error of the measurements is 1.5%. It is shown that when the degree of doping of gallium arsenide with group-VI elements is increased, the correlation of the densities of acceptor complexes with a donor-vacancy complex grows and clusters are formed.

Balagurova, E.A.; Grekov, Y.B.; Prudnikova, I.A.; Semikolenova, N.A.; Shlyakov, A.T.

1986-09-01

119

Depletion of adenosine triphosphate in Desulfovibrio by oxyanions of group VI elements  

Microsoft Academic Search

Oxyanions of elements from group VI of the periodic table, i.e., analogs of SO4\\u000a 2?, destroyed adenosine 5?-triphosphate (ATP) in cells of sulfate-respiring bacteria (Desulfovibrio spp.), probably via the ATP sulfurylase reaction. The approximate order of effectiveness was CrO4\\u000a 2?> MoO4\\u000a 2?=WO4\\u000a 2?>SeO4\\u000a 2?. Cultures of aerobically grown or nitrate-respiring bacteria were less susceptible and with fermentatively grownEscherichia coli the

Barrie F. Taylort; Ronald S. Oremland

1979-01-01

120

Negative thermal ionization mass spectrometry of main group elements Part 2. 6th group: sulfur, selenium and tellurium  

NASA Astrophysics Data System (ADS)

A systematic investigation of the formation of negative ions for the 6th main group elements using negative thermal ionization mass spectrometry (NTI-MS) is presented. A double-filament ion source with BaO on the ionization filament has been applied to reduce the work function of the rhenium filament material. S[radical sign]-, Se[radical sign]- and Te[radical sign]- were produced as most abundant ions. Low intensities of SeO[radical sign]-, SeO[radical sign]-2, TeO[radical sign]- and TeO[radical sign]-2 have also been detected. Although the electron affinity of SO2 is low, high ion currents of SO[radical sign]-2 have been observed from BaSo4 samples. This may be due to an electron capture process of this molecule rather than to a thermal ionization process. A silica gel suspension mixed with the sample enhanced the Se[radical sign]- ion current by a factor of about 40 and the Te[radical sign]- intensity by a factor of about 10. However, the silica gel showed no enhancing effect on the S[radical sign]- ion current. An improvement in the precision of the selenium and tellurium isotope ratio measurements by a factor of up to 10 was obtained when using the silica gel technique as compared with previous NTI investigations. The data of the selenium isotope abundance measurements were accepted as "best measurements" by the IUPAC.

Wachsmann, M.; Heumann, K. G.

1992-05-01

121

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

122

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

Microsoft Academic Search

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

1993-01-01

123

Retrieval Method for 3D Object Group Based on V-system  

NASA Astrophysics Data System (ADS)

Based on the V-system, an orthogonal function system over triangular domain, we proposed a retrieval method for 3D model group consisting of several separate parts. The V-system is an efficient tool to precisely represent either continuous or separate geometric objects, which is its striking characteristic. The V-system can transform a 3D object to the frequency domain based on its triangular mesh, and generate related eigenvector which is invariant to rotation, translation, and scaling. With the V-system, we can successfully extend the orthogonal transformation methods widely used in 2D image retrieval to 3D model retrieval. Retrieval experimental results show that the proposed approach is practical and effective; and it has distinct advantage for model group retrieval. Comparing with the existed 3D model retrieval measures which can only be used to retrieve single model, this new approach can be used to retrieve a model group consisting of several separate parts, which is significant and has important application value in the reuse of model groups.

Song, Ruixia; Yao, Dongxing; Wang, Xiaochun; Li, Jian; Chen, Xi; Sun, Honglei; Qi, Dongxu

124

Distribution of platinum group elements and rhenium between metallic phases of iron meteorites  

NASA Astrophysics Data System (ADS)

In situ measurement of the platinum group elements (PGE) and Re by laser ablation-ICPMS allows fractionation patterns to be established between host (kamacite) and Ni-rich exsolved phases (taenite and plessite). Measurements on two IAB iron meteorites (Canyon Diablo and Odessa) show that, for the Ni-rich phases: (a) there is no significant fractionation for Ru and Rh; (b) Pd is enriched; and (c) Ir, Os and Pt are strongly depleted. We suggest that, in the case of kamacite, taenite and plessite, the controlling mechanism is ionic size with the order of ions (small to large) being Ir-Os-Pt-(Re)-Rh-Ru-Pd. This progression plots as a smooth curve on a diagram of relative abundance distribution vs. ionic size. A comparison of PGE and Re data on iron meteorites with published data from CI chondrites indicate that there is little or no relative fractionation between the elements. The exception is Re that is clearly enriched in kamacite relative to chondrites. This confirms earlier observations on the fractionation of Re/Os between bulk IAB irons and CI values [1]. Metallic veins cutting graphite inclusions within the Canyon Diablo IAB meteorite are interpreted as a melt fraction from the iron meteorite. Abundance ratios for PGE and Re between kamacite and the metallic vein are similar to abundance ratios between kamacite and Ni-rich phases. The fact that those elements with large ionic radii (Rh, Ru and Pd) are concentrated in the metallic veins adds weight to the view that they represent a melt fraction. Our in situ measurements of the PGE and Re demonstrate that elemental fractionation takes place both during melt segregation and solid state diffusion (exsolution). The data have important implications for the Re/Os geochronometer and indicate that measurements of 187Os/ 186Os ratios on individual phases within iron meteorites may provide a potential mineral isochron.

Hirata, Takafumi; Nesbitt, Robert W.

1997-03-01

125

Heat capacity anharmonicity in elemental vanadium and V93Co7  

NASA Astrophysics Data System (ADS)

The specific heats of elemental vanadium and V93Co7 with body-centered cubic crystal structure were measured by differential scanning calorimetry from room-temperature to 1400°C. The results were compared to the harmonic phonon contribution, the electronic contribution, and the expansion against the bulk modulus contribution to the total heat capacity. The harmonic phonon contribution was obtained from the phonon densities-of-states, measured using inelastic neutron scattering. The electronic contribution to the heat capacity was obtained from ab-initio electronic band structure calculations. For the thermal expansion contribution, the room-temperature bulk and shear moduli were calculated after sound velocity measurements done by ultrasonic transduction; the coefficients of thermal expansion were measured from room-temperature up to 700°C using thermomechanical analysis. The study shows that the source of the heat capacity anharmonicity in the measured samples is phonon-phonon interaction.

Munoz, Jorge; Delaire, Olivier; Fultz, Brent

2006-10-01

126

Heat capacity anharmonicity in elemental vanadium and V93Co7  

NASA Astrophysics Data System (ADS)

The specific heats of elemental vanadium and V93Co7 with body-centered cubic crystal structure were measured by differential scanning calorimetry from room-temperature to 1400 °C. The results were compared to the harmonic phonon contribution, the electronic contribution, and the expansion against the bulk modulus contribution to the total heat capacity. The harmonic phonon contribution was obtained from the phonon densities-of-states, measured using inelastic neutron scattering. The electronic contribution to the heat capacity was obtained from ab-initio electronic band structure calculations. For the thermal expansion contribution, the room-temperature bulk and shear moduli were calculated after sound velocity measurements done by ultrasonic transduction; the coefficients of thermal expansion were measured from room-temperature up to 700 °C using thermomechanical analysis. The study shows that the source of the heat capacity anharmonicity in the measured samples is phonon-phonon interaction.

Munoz, Jorge; Delaire, Olivier; Fultz, Brent

2006-10-01

127

Lifetimes of Rydberg states in ions of the group II elements  

NASA Astrophysics Data System (ADS)

Total probabilities A nl of spontaneous radiative transitions, which determine lifetimes ? nl = 1/ A nl of nS-, nP-, nD- and nF-states in singly charged ions of the group IIa (Be+, Mg+, Ca+, Sr+, Ba+) and IIb (Zn+, Cd+, Hg+) elements, were calculated in the single-electron Fues' model potential (FMP) method. An asymptotic dependence is determined for highly excited states with small angular momentums and presented in the form ? nl = ? {/l (0)} n 3 Q l (1/ n) and numerical values of the factors ? {/l (0)} and coefficients of the cubic polynomial Q l ( x) are calculated, which approximate results of numerical computations with relative error below 2% in the range of states with principal quantum numbers from n = 7 to n ? 2000. The comparison of the numerical results with data in literature is presented, and applicability and reliability of single-electron model calculations are discussed in detail for positive singly charged ions of the group II elements.

Glukhov, I. L.; Nikitina, E. A.; Ovsiannikov, V. D.

2013-07-01

128

Electron elastic scattering cross sections from 1 keV to 100 MeV for elements Z = 1 to 100  

SciTech Connect

Tables of electron elastic scattering differential cross sections of elements (Z = 1 to 100) are given for electron energies in the range of 1 keV to 100 MeV and scattering angles in the range of 1 to 179$sup 0$. The function describing the asymmetry of a polarized electron beam after the scattering process is also included in the tables. (auth)

Storm, E.; Hancock, J.H.

1975-04-01

129

Platinum Element Group and Other Metal Element Variations at the Permo-Triassic Boundary in Kashmir and British Columbia and Their Significance  

NASA Astrophysics Data System (ADS)

The end Permian marks the greatest extinction in the geological record, but there is little consensus on whether it was caused by terrestrial or extraterrestrial factors. We report here detailed analyses of platinum group element(PGE) and other metals from relatively narrowly spaced (30 cm. in Kashmir) intervals in two expanded sections from the Permo-Triassic northern and southern hemispheres that confirm a terrestrial volcanic source for the elements. But a mechanism is required that can distribute such elements world-wide from their volcanic sources, currently only exposed in the Permo-Triassic northern hemisphere.

Brookfield, M. E.; Schnellnutt, G.; Qi, L.; Hannigan, R.; Bhat, G. M.; Wignall, P.

2009-05-01

130

An explanation of the correlations of abundance ratio between neutron-capture elements and iron group elements in Ba stars  

NASA Astrophysics Data System (ADS)

The chemical abundances of the Ba stars are excellent information for setting constraints on models of s-processes nucleosynthesis. In this work, we adopt a new analysis approach to determine the relative contributions from individual neutron-capture processes to the elemental abundances of Ba stars. We find that the production of s-process elements should accompany by the production of Cu and Zn, the calculated results on Cu and Zn abundances are in quite good agreement with observed data. The observed [Cu, Zn/Fe]-[s/Fe] correlations of Ba stars can be explained by binary scenario in which Ba stars formed.

Shen, Xiao-jing; Zhang, Bo; Li, Hong-jie; Liang, Shuai; Cui, Wen-yuan

2013-02-01

131

Ab initio effective core potentials for molecular calculations. Potentials for main group elements Na to Bi  

SciTech Connect

A consistent set of ab initio effective core potentials (ECP) has been generated for the main group elements from Na to Bi using the procedure originally developed by Kahn. The ECP's are derived from all-electron numerical Hartree--Fock atomic wave functions and fit to analytical representations for use in molecular calculations. For Rb to Bi the ECP's are generated from the relativistic Hartree--Fock atomic wave functions of Cowan which incorporate the Darwin and mass--velocity terms. Energy-optimized valence basis sets of (3s3p) primitive Gaussians are presented for use with the ECP's. Comparisons between all-electron and valence-electron ECP calculations are presented for NaF, NaCl, Cl/sub 2/, Cl/sub 2//sup -/, Br/sub 2/, Br/sub 2//sup -/, and Xe/sub 2//sup +/. The results show that the average errors introduced by the ECP's are generally only a few percent.

Wadt, W.R.; Hay, P.J.

1985-01-01

132

Theoretical studies on vibrational spectra of some halides of group IVB elements.  

PubMed

The vibrational spectra of group IVB elements halides MX4 (M=Ti(IV), Zr(IV), Hf(II); X=F, Cl, Br and I), have been investigated by ab initio RHF, MP2 and density functional theory B3LYP method with LanL2DZ basis sets. The optimized geometries, calculated vibrational frequencies and Far-IR intensities of MX4 are evaluated via comparison with experimental data. The vibrational frequencies, calculated by these methods, are compared to each other. The results indicate that B3LYP method is more reliable than RHF and MP2 methods for the frequencies calculations for these compounds. With this method, some vibrational frequencies of M2X6(2+)(M=Ti(IV), Zr(IV) and Hf(II); X=F, Cl, Br and I) are also predicted. PMID:16384738

Zhang, Yu; Zhao, Jianying; Tang, Guodong; Zhu, Longgen

2005-12-27

133

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

134

Divisions i and III / Working Group: Cartographic Coordinates and Rotational Elements  

NASA Astrophysics Data System (ADS)

As in the past, the primary activity of the IAU Working Group on Cartographic Coordinates and Rotational Elements has been to prepare and publish a triennial (``2009'') report containing current recommendations for models for Solar System bodies (Archinal et al. (2011a)). The authors are B. A. Archinal, M. F. A'Hearn, E. Bowell, A. Conrad, G. J. Consolmagno, R. Courtin, T. Fukushima, D. Hestroffer, J. L. Hilton, G. A. Krasinsky, G. Neumann, J. Oberst, P. K. Seidelmann, P. Stooke, D. J. Tholen, P. C. Thomas, and I. P. Williams. An erratum to the ``2006'' and ``2009'' reports has also been published (Archinal et al. (2011b)). Below we briefly summarize the contents of the 2009 report, a plan to consider requests for new recommendations more often than every three years, three general recommendations by the WG to the planetary community, other WG activities, and plans for our next report.

Archinal, Brent A.; Seidelmann, P. Kenneth; A'Hearn, Michael F.; Conrad, Albert R.; Consolmagno, Guy J.; Courtin, Régis; Fukushima, Toshio; Hestroffer, Daniel; Hilton, James L.; Neumann, Gregory A.; Oberst, Jürgen; Stooke, Philip J.; Tholen, David J.; Thomas, Peter C.; Williams, Iwan P.

2012-04-01

135

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

PubMed

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

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

2012-10-31

136

Effects of Cu2+ on morphological structure, functional groups, and elemental composition of aerobic granular sludge.  

PubMed

Aerobic granular sludge (AGS) is shaped by the self-immobilization of microorganisms. In this study, AGS was cultivated successively in a column sequencing batch reactor (SBR) with glucose and sodium acetate as the carbon sources. The shock-loading effects of varying the Cu2+ concentration (0.0, 1.0, 3.0, 5.0, or 10.0 mg/L) on the characteristics of aerobic granules were studied. The results show that Cu2+ has a toxic effect on the aerobic granules. Although the aerobic granules became increasingly loose as the Cu2+ concentration increased from 1.0 to 5.0 mg/L, their structural integrity was largely maintained. However, the aerobic granules disintegrated and their skeletons consisting of internal filamentous bacteria were exposed at the Cu2+ concentration of 10.0mg/L. The functional groups -NH2, -OH, -COOH, and C-N reacted with Cu2+. Ca, Fe, and P were the major trace elements observed in the AGS. With an increase in the Cu2+ concentration from 0.0 to 10.0 mg/L, the weight percentages of the essential elements Fe, Ca, Na, and K in the granules decreased from 23.98%, 24.64%, 3.86%, and 3.87% to 14.90%, 13.93%, 0%, and 0%, respectively, whereas the weight percentage of copper increased correspondingly from 0% to 35.43%. Cu2+ was exchanged with the essential metals and chelated by the nitrogen-containing functional groups (-NH2 or C-N) of the protein. These effects influenced the structural stability of the sludge. PMID:23530333

Zheng, Xiao-Ying; Wang, Xing-Nan; Huang, Xi; Chen, Qing; Chen, Wei; He, Yu-Jie

137

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

NASA Astrophysics Data System (ADS)

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.; Fan, D. S.; Hirono, Y.; Wu, J.; Morgan, T. A.; Hu, X.; Yu, S. Q.; Wang, Zh. M.; Salamo, G. J.

2011-12-01

138

Adaptive Group Detection Based on the Sort-Descending QR Decomposition for V-BLAST Architectures  

NASA Astrophysics Data System (ADS)

Combining the sphere decoding (SD) algorithm and the sequential detection method, we propose an adaptive group detection (AGD) scheme based on the sort-descending QRD (S-D-QRD) for V-BLAST architectures over an i.i.d. Rayleigh flat fading channel. Simulation results show that the proposed scheme, which encompasses the SD algorithm and the sequential detection method as two extreme cases in a probability sense, can achieve a very flexible tradeoff between the detection performance and computational complexity by adjusting the group parameter.

Jing, Xiaorong; Zhang, Tianqi; Zhou, Zhengzhong

139

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

140

vHOG, a multispecies vertebrate ontology of homologous organs groups  

PubMed Central

Motivation: Most anatomical ontologies are species-specific, whereas a framework for comparative studies is needed. We describe the vertebrate Homologous Organs Groups ontology, vHOG, used to compare expression patterns between species. Results: vHOG is a multispecies anatomical ontology for the vertebrate lineage. It is based on the HOGs used in the Bgee database of gene expression evolution. vHOG version 1.4 includes 1184 terms, follows OBO principles and is based on the Common Anatomy Reference Ontology (CARO). vHOG only describes structures with historical homology relations between model vertebrate species. The mapping to species-specific anatomical ontologies is provided as a separate file, so that no homology hypothesis is stated within the ontology itself. Each mapping has been manually reviewed, and we provide support codes and references when available. Availability and implementation: vHOG is available from the Bgee download site (http://bgee.unil.ch/), as well as from the OBO Foundry and the NCBO Bioportal websites. Contact: bgee@isb-sib.ch; frederic.bastian@unil.ch

Niknejad, Anne; Comte, Aurelie; Parmentier, Gilles; Roux, Julien; Bastian, Frederic B.; Robinson-Rechavi, Marc

2012-01-01

141

The eclipsing binary star V380 Gem: First V and Rc light curve analysis and estimation of its absolute elements  

NASA Astrophysics Data System (ADS)

We obtained complete V and Rc light curves of the eclipsing binary V380 Gem in 2012. With our data we were able to determine six new times of minimum light and refine the orbital period of the system to 0.3366088 days. The 2003 version of the Wilson–Devinney code was used to analyze the light curves in the V and Rc bands simultaneously. It is shown that V380 Gem may be classified as an W-type W Ursae Majoris system with a high mass ratio q = 1.45, a degree of contact f = 10.6% the same temperature for both the components (?T = 10 K) and an orbital inclination of i = 81.5°. Our observations show symmetric light curves in all passbands with brightness in both maxima at the same level. The absolute dimensions of V380 Gem are estimated and its dynamical evolution is inferred.

Barani, C.; Martignoni, M.; Acerbi, F.

2013-10-01

142

Iii-V Compound Semiconductor Integrated Charge Storage Structures for Dynamic and Non-Volatile Memory Elements  

NASA Astrophysics Data System (ADS)

This thesis presents an investigation into a novel group of GaAs charge storage devices. These devices, which are an integration of bipolar and junction field effect transistor structures were conceived, designed, fabricated, and tested within this study. The purpose was to analyse new types of charge storage devices, which are suitable for fabrication and lead to the development of dynamic and nonvolatile memories in III-V compound semiconductors. Currently, III-V semiconductor storage devices consist only of capacitors, where data is destroyed during reading and electrical erasure is difficult. In this work, four devices types were demonstrated that exhibit nondestructive reading, and three of the prototypes can be electrically erased. All types use the junction field effect transistor (JFET) for charge sensing, with each having different bipolar or epitaxial layer structure controlling the junction gate. The bottom epitaxial layer in each case served as the JFET channel. Two of the device types have three alternately doped layers, while the remaining two have four alternately doped layers. In all cases, removal of majority carriers from the middle layers constitutes stored charge. The missing carriers deplete the current carrying a region of the JFET channel. Drain current of the JFET becomes an indicator of stored charge. The basic function of each JFET memory element type is independent of interchanging n- and p- type doping within the structure type. Some performance advantage can be realized, however, by sensing with an n-type channel as compared to p- type due to increased carrier mobility. All device types exhibit storage time characteristics of order ten seconds. Devices are constructed in epitaxial layers grown by molecular beam epitaxy (MBE) reactors. The design of the epitaxial layers is an intrinsic part, together with the electrical design, of the storage device concept. These concepts are implemented first with photolithography masks which are used in device fabrication. The fabrication methods employ wet chemical etching and ohmic metal liftoff techniques. Electrical dc and charge retention time characteristics along with functionality read/write operations for the memory element group are measured using commercial electronic test equipment.

Hetherington, Dale Laird

143

Sioux County: an orthocumulate, and systematics of V and other trace elements in several similar eucrites  

NASA Astrophysics Data System (ADS)

Sioux County (SC) has long been classified as the most 'primitive' of the noncumulate eucrites. Stolper argued for genesis of most eucrites as little-differentiated parital melts, modified only by slight near-surface fractional crystallization. In this model, SC is the type example of a primary eucrite melt, where 'primary' denotes 'a liquid that has not changed since it was generated in its source region by melting'. Recently, Jones et al. suggested that a compositional similarity between SC and a partial melt of Murchison, confirms Stopler's model. This claim prompted us to examine the petrology of SC, which seems to have been unstudied for decades. The texture of SC is in most areas highly brecciated, with sufficient diversity in grain size to raise doubts as to whether the rock is even monomict. We find the pyroxenes are mostly pigeonites that have thoroughly exsolved. The SC bulk composition is displaced from the average noncumulate eucrite toward higher mg and V, and lower Sc and Rare Earth Elements (REE). We interpret SC as an orthocumulate. The parent melt was considerably more evolved than the observed SC composition, and had a slight (-) Eu anomaly. We note a general tendency for the more slowly cooled monomict eucrites, to feature compositions with higher mg, high V, and lower REE than their more rapidly cooled counterparts. Only a relative few eucrites are likely to be compositionally close to the melts from which they crystallized. The same parent body has also yielded many orthopyroxenites with mg ratios implying parent liquids more magnesian than any noncumulate eucrite. Absence of quenched liquids as ferroan as the cumulate parent melts suggests that the cumulates formed fairly deep within the crust.

Warren, P. H.; Kallemeyn, G. W.

1994-07-01

144

Determination of 13 elements with atomic numbers between 12 and 47 by 14MeV helium-3 activation analysis  

Microsoft Academic Search

Nuclear reactions for the trace determination of the elements Mg, Al, Ti, V, Cr, Mn, Fe, Ni, Zn, Zr, Nb, Mo, and Ag by activation analysis with 14-MeV ³He ions were investigated. For these reactions, thick target yields were measured and interference-free detection limits were calculated. For an irradiation of 1 h or 1 half-life, whichever is shorter depending on

C. S. Sastri; H. Petri; G. Erdtmann

1977-01-01

145

Architectural and functional diversity of polycomb group response elements in Drosophila.  

PubMed

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

Brown, J Lesley; Kassis, Judith A

2013-08-09

146

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

147

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

148

GPMiner: an integrated system for mining combinatorial cis-regulatory elements in mammalian gene group  

PubMed Central

Background Sequence features in promoter regions are involved in regulating gene transcription initiation. Although numerous computational methods have been developed for predicting transcriptional start sites (TSSs) or transcription factor (TF) binding sites (TFBSs), they lack annotations for do not consider some important regulatory features such as CpG islands, tandem repeats, the TATA box, CCAAT box, GC box, over-represented oligonucleotides, DNA stability, and GC content. Additionally, the combinatorial interaction of TFs regulates the gene group that is associated with same expression pattern. To investigate gene transcriptional regulation, an integrated system that annotates regulatory features in a promoter sequence and detects co-regulation of TFs in a group of genes is needed. Results This work identifies TSSs and regulatory features in a promoter sequence, and recognizes co-occurrence of cis-regulatory elements in co-expressed genes using a novel system. Three well-known TSS prediction tools are incorporated with orthologous conserved features, such as CpG islands, nucleotide composition, over-represented hexamer nucleotides, and DNA stability, to construct the novel Gene Promoter Miner (GPMiner) using a support vector machine (SVM). According to five-fold cross-validation results, the predictive sensitivity and specificity are both roughly 80%. The proposed system allows users to input a group of gene names/symbols, enabling the co-occurrence of TFBSs to be determined. Additionally, an input sequence can also be analyzed for homogeneity of experimental mammalian promoter sequences, and conserved regulatory features between homologous promoters can be observed through cross-species analysis. After identifying promoter regions, regulatory features are visualized graphically to facilitate gene promoter observations. Conclusions The GPMiner, which has a user-friendly input/output interface, has numerous benefits in analyzing human and mouse promoters. The proposed system is freely available at http://GPMiner.mbc.nctu.edu.tw/.

2012-01-01

149

Chemical trend of the formation energies of the group-III and group-V dopants in Si quantum dots  

NASA Astrophysics Data System (ADS)

Doping behavior in quantum dots (QDs) differs from that in the bulk. Despite many efforts, the doping properties are still not fully understood. Using first-principles methods, we have calculated the formation energies of various group-III acceptors and group-V donors doping at all nonequivalent sites in a Si QD (Si147H100). To analyze the trend of the formation energy, we decompose it into two terms: the unrelaxed formation energy (chemical energy) and the relaxation energy. We find that the unrelaxed formation energy generally increases as the dopant moves from the center of the QD to the surface. The variation of the unrelaxed formation energy in the surface region is explained by the variation of the local potential of the QD and the size effect. The relaxation energy gain increases as the size mismatch between the dopant and Si atom increases. Generally, the relaxation effect becomes more significant as the dopant moves toward the surface of the QD. The trend of the formation energy is determined by the two terms discussed above. If the size mismatch between the dopant and the Si atom is small, the trend of the formation energy generally follows that of the unrelaxed formation energy, increasing as the dopant moves from the center to the surface; thus, these dopants have a better chance of staying in the core region. On the other hand, if the size mismatch is large, the relaxation effect dominates and the formation energy decreases, which indicates these dopants cannot enter the core region under equilibrium growth conditions.

Ma, Jie; Wei, Su-Huai

2013-03-01

150

Human Remains from the Moravian Gravettian: Morphology and Taphonomy of Isolated Elements from the Doln?? V?stonice II Site  

Microsoft Academic Search

The excavation and palaeoanthropological analysis of the early Upper Palaeolithic site of Doln?? V?stonice II has yielded a series of incomplete and isolated human remains, comprising cranial vaults, teeth (including a series from an infant), ribs, arm bones, hand phalanges, leg bones, tarsals, metatarsals and pedal phalanges. Morphologically and morphometrically the elements are similar to those from buried individuals at

Erik Trinkaus; Jir ÿõ ´ Svoboda; Dixie L. West; Vladim??r Sládek; Simon W Hillson; Eva Drozdová; Miriam Fišáková

2000-01-01

151

The finite element analysis of stress concentration factor for the V-notch on the inner surface of cylindrical shell  

Microsoft Academic Search

This paper builds the three-dimensional finite element model of the single axial V-shaped groove on inner surface of cylindrical shell. It is obtained the influences laws of the stress concentration factor affected by the dimensionless quantities of the geometric configuration of the cylindrical shell and the groove by analyzing numerical simulation results. The function expression of the stress concentration factor

Ni Yanguang; Guo Guangli

2010-01-01

152

High-pressure phases of group-IV, III V, and II VI compounds  

NASA Astrophysics Data System (ADS)

Advances in the accuracy and efficiency of first-principles electronic structure calculations have allowed detailed studies of the energetics of materials under high pressures. At the same time, improvements in the resolution of powder x-ray diffraction experiments and more sophisticated methods of data analysis have revealed the existence of many new and unexpected high-pressure phases. The most complete set of theoretical and experimental data obtained to date is for the group-IVA elements and the group-IIIA VA and IIB VIA compounds. Here the authors review the currently known structures and high-pressure behavior of these materials and the theoretical work that has been done on them. The capabilities of modern first-principles methods are illustrated by a full comparison with the experimental data.

Mujica, A.; Rubio, Angel; Muñoz, A.; Needs, R. J.

2003-07-01

153

Growth Mechanism of Self-Catalyzed Group III-V Nanowires  

PubMed Central

Group III?V nanowires offer the exciting possibility of epitaxial growth on a wide variety of substrates, most importantly silicon. To ensure compatibility with Si technology, catalyst-free growth schemes are of particular relevance, to avoid impurities from the catalysts. While this type of growth is well-documented and some aspects are described, no detailed understanding of the nucleation and the growth mechanism has been developed. By combining a series of growth experiments using metal?organic vapor phase epitaxy, as well as detailed in situ surface imaging and spectroscopy, we gain deeper insight into nucleation and growth of self-seeded III?V nanowires. By this mechanism most work available in literature concerning this field can be described.

2010-01-01

154

Tooele NDE test report: LLNL 14-MeV Neutron Activation Group  

SciTech Connect

The concept of the 14-MeV Neutron Activation technique is to non- destructively identify unknown chemical elements or atom fractions in closed containers by irradiating the enclosed material with fast neutrons. Nuclear reactions between the neutrons and the atoms of the materials in the container will generally produce gamma rays of energies that are unique to each atom. Although the gamma ray spectra produced are sensitive only to the elements that are present -- not the specific chemical compounds -- some of the constituents of chemical weapon agents are sufficiently different from those of conventional munitions to easily distinguish them from the latter, and, in most cases, from other chemical agents. This is a non-contact method of non-destructive evaluation with a data collection time projected to be around 10--30 minutes per test item with an appropriate source and detector. Good statistical data from chlorine specimens can be obtained rapidly with a modest-strength neutron source, owing to the large radiative neutron capture cross section of chlorine. Although there is qualitative evidence for the other distinctive constituents of blister and nerve agents, namely, P, S, and F, the signature reactions for these elements have much smaller cross sections and need some combination of higher neutron flux, longer data acquisition times, or a more efficient detector. This was expected; it is evident from our preliminary data-base measurements made at LLNL, where data collection times of several hours were required to achieve good statistical accuracy in the times on the order of 10--30 minutes, we have ordered a pulsed neutron source with about two orders of magnitude greater average neutron flux than the PuBe source used for all data shown here. 4 refs., 3 figs.

Alvarez, R.A.; Rowland, M.S.

1991-06-20

155

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

Microsoft Academic Search

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

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

1988-01-01

156

Platinum-group elements in mafic and ultramafic rocks in Alaska  

SciTech Connect

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

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

1993-04-01

157

Platinum group element and nickel sulphide ore tenors of the Mount Keith nickel deposit, Yilgarn Craton, Australia  

Microsoft Academic Search

A set of platinum group element (PGE) analyses of about 120 samples from a 250-m continuous drill core through the Mount Keith\\u000a komatiite-hosted nickel orebody, combined with Ni, Cu, Co, S, and major elements, reveals a complex trend of covariance between\\u000a the original cumulus components of a thick sequence of nearly pure olivine–sulphide liquid adcumulates. The intersection is\\u000a divided into

Stephen J. Barnes; Marco L. Fiorentini; Michael C. Fardon

158

Platinum-group elements in sills of the Jurassic Ferrar Large Igneous Province from Northern Victoria Land, Antarctica  

Microsoft Academic Search

Platinum-group element (PGE) abundances were analysed in basaltic andesites and andesites from sills of the Ferrar Large Igneous Province in northern Victoria Land. The strongly fractionated primitive mantle-normalised PGE- patterns show enrichment of the Pt-PGE over the Ir-PGE. The single element abundances exhibit good correlations with the degree of differentiation of the distinctly evolved samples and are interpreted to result

R. Hanemann; L. Viereck-Goette

159

Issues of platinum group element concentration analysis: Do we have solutions?  

NASA Astrophysics Data System (ADS)

When addressing digestion techniques, sample inhomogeneity, reagent blanks and spike sample equilibration are issues of major concern. The issue of complete digestions is often overseen or neglected. Reasons are a) the lack of reference materials certified for PGE concentrations to validate methods, b) too few collaborative trials concerning PGE analysis (proficiency tests), c) assumptions made on complete digestions, d) the lack of alternative digestions method to validate analytical methods and e) large measurement uncertainties that do not allow for detection of bias. Acid digestions in Carius tubes (CT) where originally introduced (ca 1860) to digest organic material for major element analyses. In the 1940 CT were described as effective digestion method of platinum group elements applying temperatures of up to 300° C. In the early 1990s CT heated to about 230° C for silicate rock digestions for the Re-Os isotopic analysis. With the increasing interest in determining PGE with isotope dilution ICP-MS, CT were later on used for sample digestions, partially replacing the classical fire assay technique with NiS. The temperature of 230° C was thought to be sufficient for complete digestion and was not raised due to safety concerns. Recent studies show that CT do not release all the PGE contained in peridotites. It can be demonstrated that higher temperatures (greater 300° C) need to be attained to achieve complete digestions. The use of a high pressure asher (HPA-S) device makes complete PGE digestions of less than 4 g of silicates or chromites at temperatures up to 320° C in a extremely safe environment possible. The recent reintroduction of the original constructions for CT digestions of the 1940s now allow digestions even at 345° C and more. The home made device, which was build after the plan from NIST, is probably as efficient as HPA-S digestions. One advantage of the classical NiS fire assay is the possibility to process large sample amounts which should reduce the sampling effect. Since the results obtained by repeated digestions at high temperature digestions with a HPA-S or with high temperature CT show smaller relative standard deviations and higher concentrations than NiS fire assay digestions. Hence sample inhomogeneity is not the most important source of measurement uncertainty.

Meisel, T.; Becker, H.; Walker, R. J.

2004-05-01

160

Platinum-group element distribution in the oxidized Main Sulfide Zone, Great Dyke, Zimbabwe  

NASA Astrophysics Data System (ADS)

In the Great Dyke mafic/ultramafic layered intrusion of Zimbabwe, economic concentrations of platinum-group elements (PGE) are restricted to sulfide disseminations in pyroxenites of the Main Sulfide Zone (MSZ). Oxidized ores near the surface constitute a resource of ca. 400 Mt. Mining of this ore type has so far been hampered due to insufficient recovery rates. During the oxidation/weathering of the pristine ores, most notably, S and Pd are depleted, whereas Cu and Au are enriched. The concentrations of most other elements (including the other PGE) remain quite constant. In the oxidized MSZ, PGE occur in different modes: (1) as relict primary PGM (mainly sperrylite, cooperite, and braggite), (2) in solid solution in relict sulfides (dominantly Pd in pentlandite, up to 6,500 ppm Pd and 450 ppm Pt), (3) as secondary PGM neoformations (i.e., Pt-Fe alloy and zvyagintsevite), (4) as PGE oxides/hydroxides that replace primary PGM as the result of oxidation, (5) hosted in weathering products, i.e., iron oxides/hydroxides (up to 3,600 ppm Pt and 3,100 ppm Pd), manganese oxides/hydroxides (up to 1.6 wt.% Pt and 1,150 ppm Pd), and in secondary phyllosilicates (up to a few hundred ppm Pt and Pd). In the oxidized MSZ, most of the Pt and Pd are hosted by relict primary and secondary PGM; subordinate amounts are found in iron and manganese oxides/hydroxides. The amount of PGE hosted in solid solution in sulfides is negligible. Considerable local variations in the distribution of PGE in the oxidized ores complicate a mineralogical balance. Experiments to evaluate the PGE recovery from oxidized MSZ ore show that using physical concentration techniques (i.e., electric pulse disaggregation, hydroseparation, and magnetic separation), the PGE are preferentially concentrated into smaller grain size fractions by a factor of 2. Highest PGE concentrations occur in the volumetrically insignificant magnetic fraction. This indicates that a physical preconcentration of PGE is not feasible and that chemical, bulk-leaching methods need to be developed in order to successfully recover PGE from oxidized MSZ ore.

Locmelis, Marek; Melcher, Frak; Oberthür, Thomas

2010-01-01

161

Site-dependent ambipolar charge states induced by group V atoms in a silicon surface.  

PubMed

We report that solitary bismuth and antimony atoms, incorporated at Si(111) surfaces, induce either positive or negative charge states depending on the site of the surface reconstruction in which they are located. This is in stark contrast to the hydrogenic donors formed by group V atoms in silicon bulk crystal and therefore has strong implications for the design and fabrication of future highly scaled electronic devices. Using scanning tunnelling microscopy (STM) and density functional theory (DFT) we determine the reconstructions formed by different group V atoms in the Si(111)2 × 1 surface. Based on these reconstructions a model is presented that explains the polarity as well as the location of the observed charges in the surface. Using locally resolved scanning tunnelling spectroscopy we are furthermore able to map out the spatial extent over which a donor atom influences the unoccupied surface and bulk electronic states near the Fermi-level. The results presented here therefore not only show that a dopant atom can induce both positive and negative charges but also reveal the nature of the local electronic structure in the region of the silicon surface where an individual donor atom is present. PMID:23186379

Studer, Philipp; Brázdová, Veronika; Schofield, Steven R; Bowler, David R; Hirjibehedin, Cyrus F; Curson, Neil J

2012-11-27

162

Evolution of the transposable element mariner in the Drosophila melanogaster species group  

Microsoft Academic Search

The population biology and molecular evolution of the transposable element mariner has been studied in the eight species of the melanogaster subgroup of the Drosophila subgenus Sophophora. The element occurs in D. simulans, D. mauritiana, D. sechellia, D. teissieri, and D. yakuba, but is not found in D. melanogaster, D. erecta, or D. orena. Sequence comparisons suggest that the mariner

P. Capy; J. R. David; D. L. Hartl

1992-01-01

163

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

Microsoft Academic Search

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

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

2005-01-01

164

Complex anthropogenic sources of platinum group elements in aerosols on cape cod, USA.  

PubMed

Platinum group elements (PGE) of anthropogenic origin have been reported in rainwater, snow, roadside soil and vegetation, industrial waste, and urban airborne particles around the world. As recent studies have shown that PGE are bioavailable in the environment and pose health risks at chronic levels, the extent of PGE pollution is of global concern. In this study, we report PGE concentrations and osmium isotope ((187)Os/(188)Os) ratios of airborne particles (particulate matter, PM10) collected in Woods Hole, a small coastal village on Cape Cod, Massachusetts, U.S.A. The sampling site is more than 100 km away from the nearest urban centers (Boston, Providence) and has no large industrial emission center within a 30 km radius. The study reveals that, although PGE concentrations in rural airborne particulate matter are orders of magnitude lower than in urban aerosols, 69% of the total osmium is of anthropogenic origin. Anthropogenic PGE signatures in airborne particles are thus not restricted to large cities with high traffic flows and substantial industries; they can also be found in rural environments. We further conclude that the combination of Pt/Rh concentration ratios and (187)Os/(188)Os composition can be used to trace PGE sources. The Pt/Rh and (187)Os/(188)Os composition of Woods Hole aerosols indicate that the anthropogenic PGE fraction is primarily sourced from ore smelting processes, with possible minor contributions from fossil fuel burning and automobile catalyst-derived materials. Our results further substantiate the use of (187)Os/(188)Os in source apportionment studies on continental scales. PMID:23915354

Sen, Indra S; Peucker-Ehrenbrink, Bernhard; Geboy, Nicholas

2013-08-27

165

Proposals of nuclear spin quantum memory in group-IV elemental and II-VI semiconductors  

NASA Astrophysics Data System (ADS)

Schemes for the nuclear spin quantum memory are proposed based on a system composed of two electrons or one electron coupled to a single nuclear spin in isotopically purified group-IV elemental and II-VI compound semiconductors. The qubit consists of the singlet state and one of the triplet states of two electrons or simply of an electron spin. These systems are free from the decoherence due to the nuclear dipole-dipole interaction and are advantageous for the long memory time. In the case of two electrons, the protocol for the quantum state transfer between the electron-spin qubit and the nuclear spin qubit is based on the magnetic or electric field tuning of the singlet-triplet state crossing and on the hyperfine coupling supplemented with a well-defined scheme to initialize the nuclear spin. In the case of a single-electron qubit, the quantum state transfer is driven by the hyperfine interaction itself without the need of the nuclear spin initialization. Many practical systems are considered, e.g., two electrons loaded on a Si or ZnSe quantum dot, a single-electron charged state in a Si quantum dot doped with a P atom, a single-electron charged S28i quantum dot doped with an isotope atom of S29i , and a localized electron system of Si:P and ZnSe:F in the bulk crystal. General aspects of these systems are investigated and a comparison of merits and demerits is made between the two-electron qubit and the single-electron qubit.

Çak?r, Özgür; Takagahara, Toshihide

2009-10-01

166

Elastic scattering of 200 keV electrons in elemental solids: experimental observation of atomic-number-dependent oscillatory behavior.  

PubMed

Mean free path of elastic electron scattering ?(el) has been measured with a 200 keV transmission electron microscope for a wide range of stable elemental solids. An oscillating behavior versus atomic number Z has been revealed, such that, within one row of the periodic table, ?(el) exhibits minimum (maximum) for elements with completed (empty) outer d shells. These ?(el)(Z) oscillations are attributed to Z dependence of the atomic density, and their importance for the interpretation of electron microscope images is demonstrated. PMID:21825363

Iakoubovskii, Konstantin; Mitsuishi, Kazutaka

2009-03-20

167

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

168

Light-rare earth element-rich minerals associated with platinum-group element mineralization in the Archean Boston Creek Flow, Ontario  

Microsoft Academic Search

Summary A variety of LREE-rich minerals are associated with late magmatic-stage platinum-group element (PGE) mineralization [S(PGE + Au) = 300 ppb) in unsheared clinopyroxenite and gabbro proximal to sheared amphibolite in the Boston Creek Flow (BCF) Al-depleted komatiitic basalt, Archean Abitibi greenstone belt, Ontario. The LREE-rich minerals are LREE-rich apatite (La2O3 + Ce2O3 = 1.5 wt%), LREE-rich epidote (Ce, La:

W. E. Stone; J. H. Crockett; M. E. Fleet

1994-01-01

169

Structural elements influencing von Willebrand factor (vWF) binding affinity for platelet glycoprotein Ib within a dispase-digested vWF fragment.  

PubMed

We investigated the structural elements in human von Willebrand factor (vWF) that influence binding affinity for platelet glycoprotein (GP) Ib using a dispase-digested vWF fragment as a prototype (residues Leu480/Val481-Gly718 of the vWF subunit; Andrews et al, Biochemistry 28:8326, 1989). The major structural features of this fragment are a large A1-loop formed by an intrachain disulfide bond between Cys509 and Cys695 and six O-linked sugar chains. The fragment was chemically modified by (1) reduction and S-carboxyamido-methylation (R/A), (2) desialylation (DS), or (3) a combination of both (R/A-DS). The GPIb binding affinity of these fragments was basically evaluated by competitive binding assay with anti-GPIb monoclonal antibody (LJ-Ib1), a receptor blocker for vWF (Sugimoto et al, Biochemistry 30:5202, 1991). Both the prototype and the R/A fragments were also assessed for their function in shear-induced platelet aggregation. Results unambiguously demonstrated that the presence of a disulfide bridge (Cys509-Cys695) within this domain downregulates the affinity of vWF to GPIb. In addition, it was also demonstrated that the terminal sialic acids attached to six o-linked sugar chains within this domain contribute to optimal functional modulation by the antibiotic ristocetin, but not by snake venom botrocetin. PMID:8068945

Miura, S; Fujimura, Y; Sugimoto, M; Kawasaki, T; Ikeda, Y; Titani, K; Yoshioka, A

1994-09-01

170

Preferential activation of peripheral blood V gamma 9+ gamma/delta T cells by group A, B and C but not group D or F streptococci.  

PubMed Central

Previous studies have established that inactivated mycobacteria are potent and selective activators of V gamma 9+/V delta 2+ human gamma/delta T cells. Here we have analysed the proliferative response of human gamma/delta T cells to five serologically distinct groups of streptococci. While heat-inactivated streptococci of all five serogroups tested (A, B, C, D and F) induced a strong proliferative response in peripheral blood mononuclear cells (PBMC), only groups A, B and C elicited a selective activation of V gamma 9+ gamma/delta T cells in 10 (serogroup B) or 11 (serogroups A and C) of 11 tested healthy individuals. In striking contrast, groups D and F streptococci failed to activate gamma/delta T cells in nine of 11 donors and induced only a weak gamma/delta T cell response in two additional individuals. Depletion of V gamma 9+ T cells before culture completely eliminated all gamma/delta T cell responses to streptococci. These data indicate that groups A, B and C (but not D or F) streptococci can be included in the growing list of selective ligands for V gamma 9+/V delta 2+ human gamma/delta T cells.

Bender, A; Kabelitz, D

1992-01-01

171

The effect of strong carbide-forming elements such as Mo, Ti, V and Nb on the microstructure of ferritic stainless steel  

Microsoft Academic Search

The effects of both stabilizing elements such as Mo, Ti, V and Nb and of homogenization on microstructure, thermal properties, and some mechanical properties of ferritic stainless steels containing 18 wt.% Cr were investigated using scanning electron microscopy, energy-dispersive spectrometry, X-ray diffraction, differential thermal analysis, microhardness measurements and Charpy V notch impact tests. These stabilizing elements formed hard MC carbides,

V Kuzucu; M Aksoy; M. H Korkut

1998-01-01

172

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

173

An ophiolithic provenance for a freshwater influenced Upper Cretaceous succession (Gosau-Group, Austria) inferred by trace elements  

NASA Astrophysics Data System (ADS)

The interplay of Late Cretaceous basin subsidence and sea-level oscillations produced a freshwater-marine succession within the Gosau Group in the basement of the Vienna Basin (Austria). Cored sections (courtesy of OMV AG) have been investigated for the boreholes Markgrafneusiedl T1 and recently for Glinzendorf T1 and Gänserndorf T3 of the Glinzendorf syncline. These sediments are supposed to correlate to similar strata of the Grünbach Formation in the outcrop area of Grünbach-Neue Welt (Lower Austria, Northern Calcareous Alps) and yield a Santonian to early Campanian age Fine grained samples were taken from the Upper Cretaceous borehole sections and were geochemically analysed (bulk rock). A lowermost succession of the borehole Markgrafneusiedl T1 from around 4100 to 4020 m interpreted as limnic deposits with relatively low carbon (-3.2 per mill VPDB) and oxygen (-5.0 per mill VPDB) isotopies is followed by marine sediments at around 3900 to 3400 m. This marine middle section has relatively higher carbon (-0.8 per mill VPDB) and oxygen (-5.1 per mill VPDB) isotope ratios. At the top between 3275 and 3200 m a limnic interval is likely again. Boron contents rise from 88 ppm on average in the non-marine parts to values up to 133 ppm in the marine intercept. Differences of the provenance of the marine and limnic parts were investigated by using concentrations and ratios of trace elements with the aim to correlate the drilling sections of the different boreholes. Non-marine successions of the Markgrafneusiedl T1 cores show higher chromium and nickel contents up to 250 ppm respectively 400 ppm while the marine intermediate is characterised by only about 110 ppm chromium and 60 ppm nickel concentrations. In addition to that the lowermost freshwater influenced samples are enriched in Cr/V-ratio relative to the Y/Ni-ratio and therefore trend to an ultramafic source. Summing up the observation of the trace elements lead to the conclusion that the provenance of the limnic succession could be ophiolithic in contrast to the marine interval. This conclusion is corroborated by the presence of chrome spinel in heavy mineral assemblages and points to a provenance from a Tethys ophiolitic suture to the south of the Northern Calcareous Alps.

Hofer, Gerald; Wagreich, Michael

2010-05-01

174

The Boundary Element Formulation of the 1-Group, 1-D Nodal Equations  

SciTech Connect

A boundary element method is developed for the 1-D nodal diffusion equation in cylindrical geometry. This method retains the matrix qualities of the nodal formulation while providing an accurate computational benchmark for evaluating reactor analysis codes.

B. D. Ganapol; Abderrafi M. Ougouag

2006-06-01

175

Magnetic Properties of Uranium Compounds with Elements of the VA and VIA Groups. I. Compounds of UX Type  

Microsoft Academic Search

The magnetic properties of NaCl-type uranium compounds with group VA and group VIA elements are discussed. The assumption that J is a good quantum number is shown to be a good approximation for the ground multiplet of the uranium ion. The uranium ions are dealt with by the usual methods of crystal-field theory. They are assumed to be in the

J. Grunzweig-Genossar; M. Kuznietz; F. Friedman

1968-01-01

176

Large-angle elastic scattering of 59.54-keV photons by elements with 12<=Z<=92  

NASA Astrophysics Data System (ADS)

Elastic-scattering cross sections for 59.54-keV photons have been measured at an angle of 121° for 42 elements in the atomic region 12<=Z<=92. The measurements were performed using a 241Am radioisotope as the photon source and a Si (Li) detector. The measured cross sections have been compared with those based on the modified-relativistic form factors (MF's), a combination of the MF's and angle-independent ``anomalous'' scattering factors (MF+ASF), and the relativistic second-order S-matrix calculations. The MF cross sections are found to be enormously higher for the elements with K-shell binding energy (EK) close to the incident photon energy (Einc) of 59.54 keV. The S matrix and MF+ASF cross sections, in general, represent the trend of the measured data over the whole atomic region under investigation. These theoretical cross sections are in good agreement with the measured data for the elements with 12<=Z<=26 and, thereafter, deviate with increasing Z. The S matrix and MF+ASF values are, on the average, higher by 17%, and 24%, respectively, for the elements with 39<=Z<=67 and by 10% and 19%, respectively, for the elements with 70<=Z<=92. In case of 68Er, having a K-shell binding energy 2.1 keV lower than the incident photon energy, the MF+ASF value shows good agreement with the measured one, and the S matrix value is lower by 12%.

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

1998-06-01

177

Lanthanides and actinides among other groups of elements of the periodic table  

Microsoft Academic Search

The extent to which actinides (An) are similar to other elements of the periodic table is discussed. Actinides show certain\\u000a similarity with transition metals in trends in variation of the stability of the highest and lowest oxidation states with\\u000a increasing atomic number. Similarity between elements of the first half of the lanthanide (Ln) family and those of the second\\u000a half

N. B. Mikheev; S. A. Kulyukhin; I. V. Melikhov

2007-01-01

178

Use of 4.7 MeV alpha particles in elemental analysis and fusion reactor materials studies  

Microsoft Academic Search

The possibilities for using 4.7 MeV alpha particles produced at the U-120 CIP Cyclotron for charged particle induced X- and gamma-ray emission applications (PIXE and PIGE, respectively) and for fast neutron radiation damage simulation are presented. The combined analysis using PIGE and PIXE methods either separately or simultaneously is an excellent means of determining the relative abundances of lighter elements

B. Constantinescu; S. Dima; V. Florescu; E. A. Ivanov; D. Plostinaru; C. Sârbu

1986-01-01

179

Effect of isothermal forging on microstructure and fatigue behavior of blended elemental Ti6Al4V powder compacts  

Microsoft Academic Search

The effect of isothermal hot forging (IHF) on microstructure, pore closure, and tensile and fatigue properties of Ti-6A1-4V\\u000a blended elemental cold pressed and sintered powder compacts was investigated. Two types of sponge fines were used: (a) high\\u000a chloride produced by the Hunter sodium reduction process (HP) and (b) low chloride produced by the electrolytic process (EP).\\u000a The as-sintered HP compacts

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

1986-01-01

180

Effect of isothermal forging on microstructure and fatigue behavior of blended elemental Ti6Al4V powder compacts  

Microsoft Academic Search

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

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

1986-01-01

181

Hybrid in situ replacement for Samson group V Staphylococcus aureus aortic graft infection.  

PubMed

Aortic prosthesis replacements including extra-anatomical bypass procedures, in situ revascularisations with the neoaortoiliac system, antibiotic bounded prostheses or allogeneic grafts have high graft reinfection rates. We described a case of a 68-year-old man with Samson group V Staphylococcus aureus infection of his aortobifemoral graft. He underwent an explantation of the infected graft, wound debridement and a hybrid in situ allogeneic aortoiliofemoral replacement. During surgery one of the limbs of the cryopreserved human aortic allogeneic graft was anastomosed with the endarterectomised left common iliac artery, which later was angioplastied and stented. The closed system Jackson-Pratt drains were used to prevent perigraft fluid collection. The groin wound was treated with the vacuum-assisted closure dressing. On review in 6 months he remained symptom free. We conclude that a hybrid management of infected aortic prosthesis may reduce graft reinfection. PMID:23897382

Karpenko, A A; Ignatenko, P V; Beliaev, A M

2013-07-29

182

ROLE OF SURFACE FUNCTIONAL GROUPS IN THE CAPTURE OF ELEMENTAL MERCURY AND MERCURIC CHLORIDE BY ACTIVATED CARBONS  

EPA Science Inventory

The paper discusses using a laboratory-scale, fixed bed apparatus to study the role of surface functional groups (SFGs) in the capture of mercuric chloride (HgC12) and elemental mercury (Hgo) in nitrogen (N2) prior to flue gas atmosphere studies. The study focused on two activat...

183

Role of Surface Functional Groups in the Capture of Elemental Mercury and Mercuric Chloride by Activated Carbons.  

National Technical Information Service (NTIS)

The role of acidic and alkaline surface functional groups (SFG) in the capture of mercuric chloride and elemental mercury in nitrogen prior to flue gas atmosphere studies was studied using a laboratory-scale, fixed bed apparatus. The study focused on two ...

S. B. Ghorishi R. M. Keeney B. K. Gullett

2000-01-01

184

Exciton annihilation and dissociation dynamics in group II-V Cd3P2 quantum dots.  

PubMed

Semiconductor quantum dots (QDs) have emerged as a new class of light harvesting materials for solar energy conversion due to their unique size-dependent properties. Most recent studies have focused on II-VI group (such as CdX, X = S, Se, and Te) QDs and lead salt (such as PbS, PbSe, and PbTe) QDs. In this paper, we investigate exciton dissociation and annihilation dynamics of Cd3P2 QDs, a low bulk band gap (0.55 eV) II-V group material, to explore their potential application as a light harvesting component for photoreduction systems. For Cd3P2 QDs with 1S exciton band at 650 nm, a long-lived single exciton state with lifetime of 259 ns and a high emission quantum yield of 65% were observed. In Cd3P2 QD-rhodamine B (RhB, an electron acceptor) complexes, excitons in QDs could be dissociated by ultrafast electron transfer to RhB (6.2 ps), and the charge separated state had a long lifetime (31 ns). Although the photoinduced electron transfer rate in QD-RhB complexes decreased with increasing QD size, electron transfer was observed in QDs with 1S exciton bands at wavelength as long as 1050 nm. Compared with CdSe and PbS, Cd3P2 QDs with both more strongly reducing excited states and broader absorption in the visible and near IR region can be readily achieved, making them potential photosensitizers for photodriven water or CO2 reduction reactions. PMID:23611312

Wu, Kaifeng; Liu, Zheng; Zhu, Haiming; Lian, Tianquan

2013-05-24

185

Labile trace elements in basaltic achondrites: Can they distinguish between meteorites from the Moon, Mars, and V-type asteroids?  

NASA Astrophysics Data System (ADS)

We report data for 14 mainly labile trace elements (Ag, Au, Bi, Cd, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn) in eight whole-rock lunar meteorites (Asuka [A-] 881757, Dar al Gani [DaG] 262, Elephant Moraine [EET] 87521, Queen Alexandra Range [QUE] 93069, QUE 94269, QUE 94281, Yamato [Y-] 793169, and Y-981031), and Martian meteorite (DaG 476) and incorporate these into a comparative study of basaltic meteorites from the Moon, Mars, and V-type asteroids. Multivariate cluster analysis of data for these elements in 14 lunar, 13 Martian, and 34 howardite, eucrite, and diogenite (HED) meteorites demonstrate that materials from these three parents are distinguishable using these markers of late, low-temperature episodes. This distinguishability is essentially as complete as that based on markers of high-temperature igneous processes. Concentrations of these elements in 14 lunar meteorites are essentially lognormally distributed and generally more homogeneous than in Martian and HED meteorites. Mean siderophile and labile element concentrations in the 14 lunar meteorites indicate the presence of a CI-equivalent micrometeorite admixture of 2.6% When only feldspathic samples are considered, our data show a slightly higher value of 3.4% consistent with an increasing micrometeorite content in regolith samples of higher maturity. Concentrations of labile elements in the 8 feldspathic samples hint at the presence of a fractionated highly labile element component, possibly volcanic in origin, at a level comparable to the micrometeorite component. Apparently, the process(es) that contributed to establishing lunar meteorite siderophile and labile trace element contents occurred in a system open to highly labile element transport.

Wolf, Stephen F.; Wang, Ming-Sheng; Lipschutz, Michael E.

2009-06-01

186

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

SciTech Connect

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

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

2012-04-15

187

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

NASA Astrophysics Data System (ADS)

This study investigates the effects of black shale weathering on the Re-Os isotope system, platinum group element concentrations and the degradation of organic matter. Samples from a weathering profile in Late Devonian (~365 Myr) Ohio Shale show a pronounced decrease (~77%) in organic carbon (Corg) near the present soil surface, relative to the interior portion of the outcrop. A similar trend is observed for total N (~67% loss). Conversely, organic phosphorus (Porg) concentrations increase by ~59% near the soil surface. The decrease in Corg is accompanied by a pronounced decrease in Re (~99%) and, to a lesser extent, Os (~39%). Palladium and Pt do not appear to be significantly mobile. The effects of Re and Os mobility on the Re-Os isotope system are significant: none of the samples plots on a 365 Myr isochron. Rather, the samples define a trend with a slope corresponding to an age of ~18 Myr with an initial 187Os/188Os of ~6.1. This indicates recent disturbance of the Re-Os system. Isotope mass balance calculations imply that the labile fraction of Os is significantly more radiogenic (187Os/188Os of ~7.8) than the average of the unweathered samples (187Os/188Os of ~6.4). Based on data from this study, the molar ratio of labile Re to Corg in Ohio Shale is estimated at 7×10-8. We estimate the present-day riverine, black shale-derived Re flux to seawater using literature data on Re burial in anoxic marine sediments, and assuming steady-state between Re release during black shale weathering and Re burial in anoxic marine sediments. Then, the labile Re/Corg observed in this study implies that ~0.5 Tmol of Corg is released annually from weathering of black shales, a trace lithology in the continental crust. This flux corresponds to ~12% of the estimated annual CO2 flux from oxidative weathering of sedimentary rocks. The labile molar Re/Os of ~270 indicates that black shale weathering releases ~130 mol Os per year, which accounts for ~7% of the riverine Os input to seawater. The data from this study support the notion that the crustal cycles of labile Corg, Re and Os are tightly coupled. Gray shales, which are less Corg-, Re- and Os-rich, but much more abundant in the continental crust than black shales, are likely to be even more important continental sources of Re and Os to seawater.

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

2002-05-01

188

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

189

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

NASA Astrophysics Data System (ADS)

Differential cross sections for the elastic scattering of 22.1-keV photons by 30 elements in the atomic region 12<=Z<=92 have been measured at an angle of 117°. The measurements were performed under vacuum using Si(Li) detector and 109Cd radioisotope as photon source. The intensity of incident photons, detector efficiency, and other geometrical factors was determined by measuring the K x-ray yields from targets of various elements with 30<=Z<=52 excited by photons from 109Cd and 241Am radioactive sources and from the knowledge of K x-ray fluorescence cross sections. The present measured elastic scattering cross sections have been compared with those obtained in the independent-particle approximation through calculations of modified-relativistic form factors (MF's), a combination of MF"s and angle-independent 'anomalous' scattering factors (ASF's), and the relativistic second-order S matrix. The MF values are found to be enormously larger than the measured ones in case of elements with K-shell or L1-subshell binding energy in the vicinity of 22.1-keV incident photon energy, and exhibit general agreement for other elements. The MF values in combination with ASF's and the S-matrix values are found to be on an average higher by 9% and 12%, respectively, than the measured values. These deviations increase up to 20% in case of elements with K-shell or L1-subshell binding energy just below the incident photon energy, and further decrease to ~5% in case of elements with K-shell binding energy above the incident photon energy. The measured values for Al and Mg having electron binding energies far away from the incident photon energy show good agreement with different calculations.

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

1997-05-01

190

76 FR 39870 - PJM Interconnection, LLC; PJM Power Providers Group v. PJM Interconnection, LLC; Notice of Date...  

Federal Register 2010, 2011, 2012, 2013

...Energy Regulatory Commission [Docket No. ER11-2875-001; Docket No. EL11-20-001] PJM Interconnection, LLC; PJM Power Providers Group v. PJM Interconnection, LLC; Notice of Date for Staff Technical Conference and Related...

2011-07-07

191

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

192

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

Microsoft Academic Search

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

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

2000-01-01

193

Passion, containment, and commitment-essential elements of groups across the lifespan in Bruce Springsteen's work.  

PubMed

The group, with its intensity, interaction, roles and dynamics, is an important unit of experience in everyday life, in psychotherapy groups, and in Bruce Springsteen's music. This paper explores experiences of and ideas about real life groups throughout the lifecycle through Springsteen's music, framed in concepts from a broad group literature including clinical psychology, social psychology, group psychotherapy, sociology, anthropology, and organizational psychology. The lifecycle includes adolescence and the role of the group to contain all its passions; the work world with its excitements and disillusionments; encounters with loss, and the holding power of the group; experiences of dissolution of the group, and possibilities for recommitment; and the passion and support of the group during celebrations. Themes of passion, containment, and commitment weave throughout the narrative. PMID:22974151

Mangione, Lorraine

2012-10-01

194

Large-angle elastic scattering of 88.03-keV photons by elements with 30<=Z<=92  

NASA Astrophysics Data System (ADS)

Elastic-scattering differential cross-sections for 88.03-keV photons have been measured at an angle of 125° for 17 elements in the atomic region 30<=Z<=92. The measured elastic-scattering cross-sections have been compared with those obtained in the independent-particle approximation through calculations of the modified-relativistic form factors (MFs), a combination of the MFs and angle-independent `anomalous' scattering factors (ASFs), and the relativistic second-order S-matrix. The S-matrix cross-sections, in general, represent the trend of the measured data over the whole atomic region under investigation. However, these values are, on an average, lower by 10% than the measured ones. The MF cross-sections, in general, exhibit considerable deviations (~30%) from the measured values. In the case of Bi with K-shell binding energy, EK(Bi)=90.526 keV, just above the incident photon energy (Einc) of 88.03 keV, the MF cross-section is found to be enormously (~5 times) higher than the measured value. The MF cross-sections in combination with ASFs are in good agreement with the measured values for all the elements except for Pb (EK(Pb)=88.004 keV) and Bi, where these values are enormously (~28 times) smaller and higher by 31%, respectively.

Kumar, A.; Shahi, J. S.; Garg, M. L.; Puri, S.; Mehta, D.; Singh, N.

2001-10-01

195

Bacteria and Archaea Group II introns: additional mobile genetic elements in the environment  

Microsoft Academic Search

Summary Self-splicing group II introns are present in the organelles of lower eukaryotes, plants and Bacteria and have been found recently in Archaea. It is gener- ally accepted that group II introns originated in bacteria before spreading to mitochondria and chlo- roplasts. These introns are thought to be related to the progenitors of spliceosomal introns. Group II introns are also

Nicolas Toro

2003-01-01

196

Influence of oxygen compound structural elements of stretching vibration frequency of surface hydroxy groups  

Microsoft Academic Search

Stretching vibration frequencies of OH groups (? OH) in acidic oxygen compounds are determined by the electrostatic characteristics (Ep) of the polyhedron containing this group. Empirical dependence of ?OH various hydroxy groups on the number and nature of their binding cations is suggested.

A. I. Trokhimets

1986-01-01

197

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

198

Orbital Elements and Mass-Loss Rate of V 444 Cyg  

Microsoft Academic Search

The binary system HD 193576 = V 444 Cyg was observed in 1999--2006 to obtain radial velocities of its components -- O-type star and WR-type star. From the measured data of the N V 4604 emission line the orbital period P=4.212450±0.000048 days was found. This result confirms the rate of the period change given by Underhill et al. (1990). Using

A. Hirv; K. Annuk; T. Eenmäe; T. Liimets; J. Pelt; A. Puss; M. Tempel

2006-01-01

199

Utilizing Prestructured Art Elements in Brief Group Art Therapy with Adolescents  

Microsoft Academic Search

Over the past two decades there has been a steady decrease in the average length of stay in mental health programs, and this phenomenon has necessitated changes in how art therapy services are delivered. This paper presents strategies for utilizing six different prestructured art elements (magazine pictures, magazine words, photocopied images, cut and torn paper, traced shapes, and partial drawings)

Randy M. Vick

1999-01-01

200

Potential-model calculation of an order-v2 nonrelativistic QCD matrix element  

NASA Astrophysics Data System (ADS)

We present two methods for computing dimensionally regulated nonrelativistic QCD heavy-quarkonium matrix elements that are related to the second derivative of the heavy-quarkonium wave function at the origin. The first method makes use of a hard-cutoff regulator as an intermediate step and requires knowledge only of the heavy-quarkonium wave function. It involves a significant cancellation that is an obstacle to achieving high numerical accuracy. The second method is more direct and yields a result that is identical to the Gremm-Kapustin relation, but it is limited to use in potential models. It can be generalized to the computation of matrix elements of higher order in the heavy-quark velocity and can be used to resum the contributions to decay and production rates that are associated with those matrix elements. We apply these methods to the Cornell potential model and compute a matrix element for the J/? state that appears in the leading relativistic correction to the production and decay of that state through the color-singlet quark-antiquark channel.

Bodwin, Geoffrey T.; Kang, Daekyoung; Lee, Jungil

2006-07-01

201

76 FR 7836 - PJM Power Providers Group v. PJM Interconnection, L.L.C.; Notice of Complaint  

Federal Register 2010, 2011, 2012, 2013

...Regulatory Commission [Docket No. EL11-20-000] PJM Power Providers Group v. PJM Interconnection, L.L.C.; Notice of Complaint...Rules of Practice and Procedure, 18 CFR 385.206, PJM Power Providers Group (Complainant) filed a...

2011-02-11

202

Rapid detection by multiplex PCR of Genomic Islands, prophages and Integrative Conjugative Elements in V. cholerae 7th pandemic variants.  

PubMed

Vibrio cholerae poses a threat to human health, and new epidemic variants have been reported so far. Seventh pandemic V. cholerae strains are characterized by highly related genomic sequences but can be discriminated by a large set of Genomic Islands, phages and Integrative Conjugative Elements. Classical serotyping and biotyping methods do not easily discriminate among new variants arising worldwide, therefore the establishment of new methods for their identification is required. We developed a multiplex PCR assay for the rapid detection of the major 7th pandemic variants of V. cholerae O1 and O139. Three specific genomic islands (GI-12, GI-14 and GI-15), two phages (Kappa and TLC), Vibrio Seventh Pandemic Island 2 (VSP-II), and the ICEs of the SXT/R391 family were selected as targets of our multiplex PCR based on a comparative genomic approach. The optimization and specificity of the multiplex PCR was assessed on 5 V. cholerae 7th pandemic reference strains, and other 34 V. cholerae strains from various epidemic events were analyzed to validate the reliability of our method. This assay had sufficient specificity to identify twelve different V. cholerae genetic profiles, and therefore has the potential to be used as a rapid screening method. PMID:22062086

Spagnoletti, Matteo; Ceccarelli, Daniela; Colombo, Mauro M

2011-10-28

203

First Study of Anthropogenic Platinum Group Elements in Roadside Top-Soils in Athens, Greece  

Microsoft Academic Search

Concentrations of Pt and Pd in roadside top-soil samples, collected in May 2003, at four types of sites (urban, suburban,\\u000a rural and highway) in the greater Athens area as well as concentrations of Pb, Cu, Zn, Fe and Ca, were determined.\\u000a \\u000a Our results show high concentrations of “classic” (Pb, Cu, Zn) and “new” (Pt, Pd) traffic related elements in top-soils

A. N. Riga-Karandinos; C. J. Saitanis; G. Arapis

2006-01-01

204

Non-hydride systems of the main group elements as hydrogen storage materials  

Microsoft Academic Search

This review surveys the state of the art in non-hydride hydrogen storage materials composed of the elements B, C, N, O, Si, and Al. In the nitrogen-based systems Li3N and NH3BH3 hydrogen is chemically bound in the formal oxidation states +1 and ?1, whereas carbon nanotubes and aluminosilicate-based zeolites adsorb or encapsulate molecular H2. The advantages and drawbacks of each

Henrietta W. Langmi; G. Sean McGrady

2007-01-01

205

Variational and diffusion Monte Carlo study of post-d group 13-17 elements.  

PubMed

We present ab initio calculations of atomic and molecular systems containing the first-, second-, and third-row post-d elements (Ga-Br, In-I, and Tl-At) using several methods including variational and diffusion Monte Carlo. In the quantum Monte Carlo calculations, we used the recent scalar-relativistic energy-consistent Hartree-Fock pseudopotentials [M. Burkatzki et al., J. Chem. Phys. 126, 234105 (2007)], which are nonsingular at the origin. For the first- and second-row elements, the calculated ionization energies and electron affinities are in excellent agreement with those obtained using CCSD(T) with large basis sets and with experiment after correcting approximately for spin-orbit effects. For the third-row elements, where relativistic effects cannot be adequately included by a simple j-averaging, the results are in excellent agreement with CCSD(T) energies obtained with a large (5-zeta) basis set. Benchmark calculations of the dissociation energies, vibration frequencies, and equilibrium bond lengths of several diatomic molecules including As(2), Br(2), Sb(2), and I(2) as well as the hydrides XH (X = Ga, Br, In, I, and At) are presented. PMID:18715078

Al-Saidi, W A

2008-08-14

206

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

207

Contamination-free preparation of geological samples for ultra-trace gold and platinum-group element analysis  

Microsoft Academic Search

In order to determine the most contaminant-free sample processing procedures for ultra-trace platinum-group element (PGE) and gold analysis, we have crushed and milled pure quartz in a variety of media and then performed analysis by inductively coupled plasma mass spectrometry (ICP-MS) using isotope dilution (Pt, Pd, Ru and Ir) and external calibration (Au and Rh).Initial sample desegregation was best achieved

Noreen J. Evans; Jeffrey J. Davis; John P. Byrne; David French

2003-01-01

208

The chromosomal distributions of Ty1-copia group retrotransposable elements in higher plants and their implications for genome evolution  

Microsoft Academic Search

Retrotransposons make up a major fraction – sometimes more than 40% – of all plant genomes investigated so far. We have isolated\\u000a the reverse transcriptase domains of the Ty1-copia group elements from several species, ranging in genome size from some 100\\u000a Mbp to 23 000 Mbp, and determined the distribution patterns of these retrotransposons on metaphase chromosomes and within\\u000a interphase

Andrea Brandes; Shin Taketa; Thomas Schmidt; Alexander V. Vershinin; Elena G. Alkhimova; Anette Kamm; Robert L. Doudrick; Trude Schwarzacher; Andreas Katsiotis; Sybille Kubis; Amar Kumar; Steven R. Pearce; Andrew J. Flavell; Gill E. Harrison

1997-01-01

209

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

Microsoft Academic Search

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

Anders Meibom; Robert Frei; Norman H. Sleep

2004-01-01

210

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

SciTech Connect

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

David A. Dixon; Anthony J. Arduengo, III

2010-09-30

211

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

212

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

PubMed

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

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

2003-05-06

213

Physicochemical Interaction of Rhenium with Elements of the Platinum Group and Properties of Certain Alloys.  

National Technical Information Service (NTIS)

A review is given of the physicochemical interaction of rhenium with the platinum-group metals (ruthenium, osmium, tungsten, palladium, rhodium, iridium, platinum). The solubility of rhenium in these metals and vice versa is illustrated with graphs. Rheni...

I. A. Tsyganova M. A. Tylkina V. P. Polyakova

1969-01-01

214

Interactions of 200 GeV gold nuclei in light elements  

Microsoft Academic Search

Total charge-changing cross sections and partial cross-sections for interactions of 200 GeV Au-197 nuclei incident on carbon and polyethylene (CH2) targets have been measured during a calibration of the HEAO-3 Heavy Nuclei Experiment. From these, the total and partial cross-sections for Au-197 incident on hydrogen are inferred. The effects of using these cross-sections in one model of cosmic ray propagation

N. R. Brewster; R. K. Fickle; C. J. Waddington; W. R. Binns; M. H. Israel; M. D. Jones; J. Klarmann; T. L. Garrard; B. J. Newport; E. C. Stone

1983-01-01

215

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

216

Group V phospholipase A2 increases pulmonary endothelial permeability through direct hydrolysis of the cell membrane  

PubMed Central

Acute lung injury (ALI) is characterized by inflammatory disruption of the alveolar–vascular barrier, resulting in severe respiratory compromise. Inhibition of the intercellular messenger protein, Group V phospholipase A2 (gVPLA2), blocks vascular permeability caused by LPS both in vivo and in vitro. In this investigation we studied the mechanism by which recombinant gVPLA2 increases permeability of cultured human pulmonary endothelial cells (EC). Exogenous gVPLA2 (500 nM), a highly hydrolytic enzyme, caused a significant increase in EC permeability that began within minutes and persisted for >10 hours. However, the major hydrolysis products of gVPLA2 (Lyso-PC, Lyso-PG, LPA, arachidonic acid) did not cause EC structural rearrangement or loss of barrier function at concentrations <10 ?M. Higher concentrations (? 30 ?M) of these membrane hydrolysis products caused some increased permeability but were associated with EC toxicity (measured by propidium iodide incorporation) that did not occur with barrier disruption by gVPLA2 (500 nM). Pharmacologic inhibition of multiple intracellular signaling pathways induced by gVPLA2 activity (ERK, p38, PI3K, cytosolic gIVPLA2) also did not prevent EC barrier disruption by gVPLA2. Finally, pretreatment with heparinase to prevent internalization of gVPLA2 did not inhibit EC barrier disruption by gVPLA2. Our data thus indicate that gVPLA2 increases pulmonary EC permeability directly through action as a membrane hydrolytic agent. Disruption of EC barrier function does not depend upon membrane hydrolysis products, gVPLA2 internalization, or upregulation of downstream intracellular signaling.

Munoz, Nilda M.; Desai, Anjali; Meliton, Lucille N.; Meliton, Angelo Y.; Zhou, Tingting; Leff, Alan R.; Dudek, Steven M.

2012-01-01

217

More than 1000 ultraconserved elements provide evidence that turtles are the sister group of archosaurs.  

PubMed

We present the first genomic-scale analysis addressing the phylogenetic position of turtles, using over 1000 loci from representatives of all major reptile lineages including tuatara. Previously, studies of morphological traits positioned turtles either at the base of the reptile tree or with lizards, snakes and tuatara (lepidosaurs), whereas molecular analyses typically allied turtles with crocodiles and birds (archosaurs). A recent analysis of shared microRNA families found that turtles are more closely related to lepidosaurs. To test this hypothesis with data from many single-copy nuclear loci dispersed throughout the genome, we used sequence capture, high-throughput sequencing and published genomes to obtain sequences from 1145 ultraconserved elements (UCEs) and their variable flanking DNA. The resulting phylogeny provides overwhelming support for the hypothesis that turtles evolved from a common ancestor of birds and crocodilians, rejecting the hypothesized relationship between turtles and lepidosaurs. PMID:22593086

Crawford, Nicholas G; Faircloth, Brant C; McCormack, John E; Brumfield, Robb T; Winker, Kevin; Glenn, Travis C

2012-05-16

218

Gold and platinum-group element containing minerals - reflections on the reliability of observations  

Microsoft Academic Search

The textural settings of gold and platinum-group minerals (PGM) in different ores, the grain sizes of these valuable minerals, and variations in the modal proportions of different phases are important factors for the evaluation of such ores. Variations of these parameters are not only studied because they affect beneficiation, but also because they reflect changes in the intrinsic conditions under

R. K. W. Merkle

2003-01-01

219

Population-based dietary intakes and tap water concentrations for selected elements in the EPA Region V National Human Exposure Assessment Survey (NHEXAS)  

Microsoft Academic Search

A National Human Exposure Assessment Survey (NHEXAS) field study was performed in U.S. Environmental Protection Agency (EPA) Region V, providing population-based exposure distribution data for selected elements in several personal, environmental, and biological media. Population distributions are reported for the 11 elements that were measured in water and dietary samples. Dietary intakes and home tap water concentrations of lead, arsenic,

KENT W THOMAS; EDO D PELLIZZARI; MAURICE R BERRY

1999-01-01

220

Hybridoma cultivation in defined serum-free media: growth-supporting substances. V. Trace elements.  

PubMed

The effects of selenium and manganese on growth of hybridomas in serum-free medium were studied. The optimum growth-supporting concentration of Na2SeO3 was about 50 nM. Omission of selenite resulted in decreased growth (60-70% of the number of cells growing with selenite when cultivated for 3 days). The optimum growth-supporting concentration of MnCl2 was 0.5 nM. The number of hybridoma cells growing 3 days without MnCl2 represented about 80% of the cell number obtained by cultivation with MnCl2. Compounds of other trace elements did not display growth-stimulating activity, when tested in short-term culture, perhaps with the exception of lithium at relatively very high concentrations (about 0.2-0.6 mM). PMID:3391326

Kovár, J

1988-01-01

221

Fragmentation cross sections of 600 MeV/nucleon 20Ne on elemental targets  

NASA Astrophysics Data System (ADS)

Charge-changing and fragment production cross sections have been obtained for interactions of a 600 MeV/nucleon neon beam in H, C, Al, Cu, Sn, Ta, and Pb targets. The H target results were obtained using a polyethylene target and subtracting the cross sections obtained with the carbon target. At 600 MeV/nucleon, the angular distributions of the fragments are strongly forward peaked, and consequently the spectra seen in the detectors with the largest angular acceptance-corresponding to a forward cone with half angle 7°-show obvious fragment peaks only for charges 5 through 9. No clear peaks are seen below charge 5 in the large-acceptance detectors, but spectra from detectors subtending smaller angular acceptances show peaks for all fragment species, and additional identifiable peaks from events with between two and four fragments in coincidence. Production cross sections for all fragment species are reported here and, where possible, compared to earlier measurements and to the predictions of three model calculations (Nucfrg2, Qmsfrg, and an empirical parametrization that is tuned for higher-mass beams). The cross sections for fragments of charge 5 and below have not been previously reported. Also, the charge-changing cross sections are compared to earlier measurements and to Nucfrg2 and the Bradt-Peters model.

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

2001-08-01

222

Fragmentation cross sections of 600 MeV/Nucleon 20Ne on element Al targets  

SciTech Connect

Charge-changing and fragment production cross sections have been obtained for interactions of a 600 MeV/nucleon neon beam in H, C, Al, Cu, Sn, and Pb targets. The H target results were obtained using a polyethylene target and subtracting the cross sections obtained with the carbon target. At 600 MeV/nucleon, the angular distributions of the fragments are strongly forward-peaked, and consequently the spectra seen in the detectors with the largest angular acceptance - corresponding to a forward cone with half-angle 7 degrees - show obvious fragment peaks only for charges 5 through 9. No clear peaks are seen below charge 5 in the large-acceptance detectors, but spectra from detectors subtending smaller angular acceptances show peaks for all fragment species, and additional identifiable peaks from events with between two and four fragments in coincidence. Production cross sections for all fragment species, from the aforementioned targets, are reported here and, where possible are compared t o earlier measurements and to the predictions of the NUCFRG2 and QMSFRG models and an empirical parameterization that is tuned for higher-mass beams. The cross sections for fragments of charge 5 and below have not been previously reported. Also, the charge-changing cross sections are compared to earlier measurements and to NUCFRG2 and the Bradt-Peters model.

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

2000-11-01

223

NEUTRONIC REACTOR FUEL ELEMENT  

DOEpatents

A fuel element possessing good stability and heat conducting properties is described. The fuel element comprises an outer tube formed of material selected from the group consisting of stainhess steel, V, Ti. Mo. or Zr, a fuel tube concentrically fitting within the outer tube and containing an oxide of an isotope selected from the group consisting of U/sup 235/, U/sup 233/, and Pu/sup 239/, and a hollow, porous core concentrically fitting within the fuel tube and formed of an oxide of an element selected from the group consisting of Mg, Be, and Zr.

Shackleford, M.H.

1958-12-16

224

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

225

Platinum-group element abundances in xenoliths from Marsabit Volcanic field (Kenya Rift).  

NASA Astrophysics Data System (ADS)

PGE have been determined in 14 petrologically well-charaterized spinel peridotite xenoliths from the Marsabit volcanic field (Kenya Rift). The samples pertain to 3 groups previously distinguished based on their textural characteristics: porphyroclastic (I) and recryztallized (II) spl lherzolite and porphyroclastic harzburgite (III). The overall total PGE contents of Marsabit xenoliths are between 14 and 32 ppb. Whether coarse-grained, recrystallized, deformed, virtually anhydrous or modally metasomatized, all peridotites have Pd-depleted PUM-normalized PGE patterns probably inherited from an old (Archean? Proterozoic?) partial melting event. This is confirmed by the crude correlation existing between the clinopyroxene modal content of the rocks and their total PGE or the anti-correlations existing between total PGE and olivine modal content or Pd/Ir ratios and clinopyroxene modal content. Only one rock, the richest in total PGE and displaying clear signs of modal metasomatism, falls outside the trend, having high Ol and low Cpx contents. However, the shape of PGE patterns can greatly vary between or within different peridotite groups. Only group II shows coherent PGE patterns. The variability of PGE patterns and concentrations probably reflects recent magmatic history and/or ancient metasomatism. Preliminary Sr-Nd-Pb isotopic data show that the most metasomatized lherzolites display unradiogenic signatures (clinopyroxene separates and whole rock).

Bourdon, E.; Kalt, A.; Meisel, T.; Kaeser, B.

2006-12-01

226

Synthesis and characterization of group V metal carbide and nitride catalysts  

NASA Astrophysics Data System (ADS)

Group V transition metal carbides and nitrides were prepared via the temperature programmed reaction (TPR) of corresponding oxides with NHsb3 or a CHsb4/Hsb2 mixture. Except for the tantalum compounds, phase-pure carbides and nitrides were prepared. The vanadium carbides and nitrides were the most active and selective catalysts. Therefore the principal focus of the research was the preparation, characterization, and evaluation of high surface area vanadium nitride catalysts. A series of vanadium nitrides with surface areas up to 60 msp2/g was prepared. Thermal gravimetric analysis coupled with x-ray diffraction and scanning electron microscopy indicated that the solid-state reaction proceeded by the sequential reduction of Vsb2Osb5 to VOsb{0.9} and concluded with the topotactic substitution of nitrogen for oxygen in VOsb{0.9}. The transformation of Vsb2Osb5 to VN was pseudomorphic. An experimental design was executed to determine effects of the heating rates and space velocities on the VN microstructures. The heating rates had minor effects on the surface areas and pore size distributions; however, increasing the space velocity significantly increased the surface area. The materials were mostly mesoporous. Oxygen chemisorption on the vanadium nitrides scaled linearly with the surface area. The corresponding O/Vsbsurface ratio was ?0.6. The vanadium nitrides were active for butane activation and pyridine hydrodenitrogenation. During butane activation, their selectivities towards dehydrogenation products were as high as 98%. The major product in pyridine hydrodenitrogenation was pentane. The reaction rates increased almost linearly with the surface area suggesting that these reactions were structure insensitive. The vanadium nitrides were not active for crotonaldehyde hydrogenation; however, they catalyzed an interesting ring formation reaction that produced methylbenzaldehyde and xylene from crotonaldehyde. A new method was demonstrated for the production of very high surface area vanadium nitrides. Vanadium nitrides with surface areas up to ?150 msp2/g were prepared via the TPR of vanadium oxide aerogels with NHsb3. The oxide aerogels were prepared using vanadium tri-n-propoxy oxide followed by the supercritical extraction of ethanol. The vanadium oxide aerogels and resulting nitrides were mesoporous and fibrous. Gravimetric butane conversion rates for these nitrides increased almost linearly with the surface area. Butane activation rates for these high surface area vanadium nitrides were comparable to that of a commercial Pt-Sn/Alsb2Osb3 catalyst.

Kwon, Heock-Hoi

1998-11-01

227

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.

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

2012-01-01

228

DNA Macrorestriction Analysis of Nontypeable Group B Streptococcal Isolates: Clonal Evolution of Nontypeable and Type V Isolates  

PubMed Central

Group B streptococci (GBS) are serotyped according to capsular polysaccharide (CPS) type (Ia to VIII); an isolate is classified as nontypeable (NT) if no detectable CPS is found. Surface-localized protein antigens (?, ?, R1, and R4) serve as additional markers to classify GBS isolates, which is particularly useful since NT isolates often express one or more of these proteins. To compare genetic resemblance among isolates with similar protein profiles, we studied 58 NT isolates digested with the SmaI macrorestriction enzyme prior to pulsed-field gel electrophoresis (PFGE). Of these 58, 15.5% expressed ? only, 20.7% expressed ?+?, 15.5% expressed R4, and 25.8% expressed R1,R4, while 22.4% of the isolates expressed no detectable proteins. The largest PFGE profile group, with 48% of the isolates, was group 4, composed primarily of isolates that expressed R1,R4 or no proteins. The second most common profiles were 3 and 32, each with 13.8% of the isolates. Since NT isolates in profile group 4 were highly related to type V isolates, as demonstrated by PFGE profiles, we investigated 45 type V isolates. Two-thirds of the type V isolates within profile group 4 were classified into subgroup 4a, compared to 28.2% of 39 NT isolates. Only 11% of the V/R1,R4 isolates were identical to the prototype group 4 profile, in contrast to 75% of the NT/R1,R4 isolates. A shift of type V isolates into profile 4 subgroups may be indicative of a genetic change over time. PFGE is a valuable approach for comparison of GBS isolate relatedness and for monitoring of NT and typeable GBS isolates for potential clonal divergence.

Amundson, Nicole R.; Flores, Aurea E.; Hillier, Sharon L.; Baker, Carol J.; Ferrieri, Patricia

2005-01-01

229

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

NASA Astrophysics Data System (ADS)

Rare earth element (REE), major, and trace element analyses of 77 samples from the Mesozoic Franciscan Complex and Miocene Monterey Group of California (USA) indicate that magnitudes of the Ce anomaly (Ce/Ce*) and total REE abundances (SREE) in these rocks are controlled dominantly by (a) the amount of included metalliferous material, (b) the amount of direct terrigenous input, and (c) the overall burial rate. The relative importance of these individual processes varies across an ocean basin in such a way that REE relative fractionations and SREE correspond with its depositional environment. Our conclusions are supported by an extensive review of published REE data from various river, coastal, open-ocean, and ridge-influenced waters, as well as terrigenous, pelagic, and metalliferous sediment. The chert sequences record deposition in spreading ridge, open-ocean basin, and continental margin environments. The relative importance of metalliferous and terrigenous influences and the role of scavenging from seawater may be estimated from a sample's inferred depositional distance (km) from the spreading ridge, the major element chemistry, and the stratigraphie context. The Ce/Ce* values are low (~0.29) in the vicinity of spreading ridges and trend to successively higher (~ 1) values with decreasing metalliferous and increasing terrigenous influences. Other REE indicators ( REE, Lu n / La n , Eu / Eu *) also respond to metalliferous and terrigenous influences. Near the spreading ridge, chert REE appears determined by burial rate, while shale REE responds to metalliferous abundance. In open-ocean and continental margin environments, REE is controlled by sediment exposure time and therefore is related inversely to burial rate. REE data are consistent with the major elements Fe 2 O 3 , MnO, and Al 2 O 3 in reflecting the respective metalliferous and terrigenous sources. P 2 O 5 and CaO do not vary with Ce/Ce* in any environment, but CaO shows a weak negative correlation with REE. Trace element trends (e.g., V, Cr, Cu, Ge/Si, Rb, Sr, Y, Th, U) in general can similarly be accounted for in the context of depositional position relative to metalliferous and terrigenous inputs. REEs in chert appear less affected by post-depositional processes than either major or trace elements, indicating that REEs are better tools for paleoceanographic or tectonic reconstructions that are based on chert chemistry. This work complements recent efforts to elucidate the factors determining large-scale REE distributions in marine sediments and has direct bearing on previous attempts to use the Ce anomaly in older rocks and sediments as a recorder of secular variations and anoxic events in the overlying water column.

Murray, Richard W.; Buchholtz Ten Brink, Marilyn R.; Gerlach, David C.; Price Russ, G., III; Jones, David L.

1991-07-01

230

Finite element simulation of conventional and prestressed cutting of Ti6Al4V  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

231

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

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EL10-68-000] Resale Power Group of Iowa, WPPI Energy v. ITC Midwest LLC, Interstate Power and Light Company; Notice of Filing June 16, 2010. Take notice that, on June 15, 2010,...

2010-06-23

232

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

Federal Register 2010, 2011, 2012, 2013

...EL10-68-000] Resale Power Group of Iowa, WPPI Energy v. ITC Midwest LLC, Interstate Power and Light Company; Notice of...WPPI Energy (Complainants) filed a formal complaint against ITC Midwest LLC and Interstate Power and Light Company...

2010-05-26

233

Distribution of platinum-group elements and Os isotopes in chromite ores from Mayarí-Baracoa Ophiolitic Belt (eastern Cuba)  

Microsoft Academic Search

The Mayarí-Baracoa ophiolitic belt in eastern Cuba hosts abundant chromite deposits of historical economic importance. Among\\u000a these deposits, the chemistry of chromite ore is very variable, ranging from high Al (Cr#=0.43–0.55) to high Cr (Cr#=0.60–0.83)\\u000a compositions. Platinum-group element (PGE) contents are also variable (from 33 ppb to 1.88 ppm) and correlate positively with\\u000a the Cr# of the ore. Bulk PGE abundances correlate

F. Gervilla; J. A. Proenza; R. Frei; J. M. González-Jiménez; C. J. Garrido; J. C. Melgarejo; A. Meibom; R. Díaz-Martínez; W. Lavaut

2005-01-01

234

Electronic basis of the hcp, omega and bcc phases in group IVB elements under pressure or on alloying  

NASA Astrophysics Data System (ADS)

Using the first principles DFT calculations, we have elucidated the electronic basis of the ??? and the ??? transitions in group IVB elements. After considering several possible factors that could give rise to the structural stability of a particular crystal structure, the changes in the band structure energy due to Peierls-Jahn-Teller distortion and crystal-field effects on sub orbital of d bands coupled with Ewald energy differences have been identified as the causes for these transitions. The role of van Hove singularities and consequent electronic topological transitions has also been examined.

Gyanchandani, Jyoti; Sikka, S. K.

2013-03-01

235

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

NASA Astrophysics Data System (ADS)

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.

1992-09-01

236

Comparison of 14 MeV neutron activation analysis and competitive methods for determination of oxygen, nitrogen, silicon, fluorine and other elements  

Microsoft Academic Search

14 MeV neutron activation analysis (14 MeV NAA) makes use of small particle accelerators to produce 14 MeV neutrons from the D-T reaction. The neutrons produce radioactive isotopes in samples by the reactions (n,p), (n,2n) and (n,..cap alpha..). Gamma rays emitted are counted to determine the amount of the target element present. Major applications have been determination of total O,

Bild

1986-01-01

237

Hypoelectronic dimetallaheteroboranes of group 6 transition metals containing heavier chalcogen elements.  

PubMed

We have synthesized and structurally characterized several dimetallaheteroborane clusters, namely, nido-[(Cp*Mo)2B4SH6], 1; nido-[(Cp*Mo)2B4SeH6], 2; nido-[(Cp*Mo)2B4TeClH5], 3; [(Cp*Mo)2B5SeH7], 4; [(Cp*Mo)2B6SeH8], 5; and [(CpW)2B5Te2H5], 6 (Cp* = ?(5)-C5Me5, Cp = ?(5)-C5H5). In parallel to the formation of 1-6, known [(CpM)2B5H9], [(Cp*M)2B5H9], (M = Mo, W) and nido-[(Cp*M)2B4E2H4] compounds (when M = Mo; E = S, Se, Te; M = W, E = S) were isolated as major products. Cluster 6 is the first example of tungstaborane containing a heavier chalcogen (Te) atom. A combined theoretical and experimental study shows that clusters 1-3 with their open face are excellent precursors for cluster growth reactions. As a result, the reaction of 1 and 2 with [Co2(CO)8] yielded clusters [(Cp*Mo)2B4H4E(?3-CO)Co2(CO)4], 7-8 (7: E = S, 8: E = Se) and [(Cp*Mo)2B3H3E(?-CO)3Co2(CO)3], 9-10 (9: E = S, 10: E = Se). In contrast, compound 3 under the similar reaction conditions yielded a novel 24-valence electron triple-decker sandwich complex, [(Cp*Mo)2{?-?(6):?(6)-B3H3TeCo2(CO)5}], 11. Cluster 11 represents an unprecedented metal sandwich cluster in which the middle deck is composed of B, Co, and Te. All the new compounds have been characterized by elemental analysis, IR, (1)H, (11)B, (13)C NMR spectroscopy, and the geometric structures were unequivocally established by X-ray diffraction analysis of 1, 2, 4-7, and 9-11. Furthermore, geometries obtained from the electronic structure calculations employing density functional theory (DFT) are in close agreement with the solid state structure determinations. We have analyzed the discrepancy in reactivity of the chalcogenato metallaborane clusters in comparison to their parent metallaboranes with the help of a density functional theory (DFT) study. PMID:23819867

Chakrahari, Kiran Kumarvarma; Thakur, Arunabha; Mondal, Bijan; Ramkumar, V; Ghosh, Sundargopal

2013-07-02

238

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

239

Investigations of multiple backscattering and albedos of 1.12 MeV gamma photons in elements and alloys  

NASA Astrophysics Data System (ADS)

The energy and intensity distributions of multiple backscattering of 1.12 MeV gamma photons emerging from targets of elements and alloys are observed as a function of thickness and atomic number (Z) of the target. The numbers of these multiply backscattered events show an increase with increase in target thickness, and then saturate for a particular thickness of the target called saturation thickness (depth). The saturation thickness decreases with increasing atomic number and varies as e-Z. The multiple backscattering, an interfering background noise in Compton profile, has been successfully used to assign the ‘‘effective atomic number’’ to alloys. Monte Carlo calculations also support the present experimental results. The number, energy and dose albedos are also found to be saturating for the same thickness where the numbers of multiply backscattered events saturate.

Sabharwal, Arvind D.; Singh, Bhajan; Sandhu, B. S.

2009-01-01

240

Platinum group element abundances in the upper continental crust revisited - New constraints from analyses of Chinese loess  

NASA Astrophysics Data System (ADS)

Platinum group element (PGE) abundances in the upper continental crust (UCC) are poorly constrained with published values varying by up to an order of magnitude. We evaluated the validity of using loess to estimate PGE abundances in the UCC by measuring these elements in seven Chinese loess samples using a precise method that combines NiS fire assay with isotope dilution. Major and trace elements of the Chinese loess show a typical upper crustal composition and PGE abundances are consistent with literature data on Chinese loess, except for Ru, which is a factor of 10 lowe than published values. We suggest that the high Ru data and RuN/IrN values of Chinese loess reported by Peucker-Ehrenbrink and Jahn (2001) (Geochem. Geophys. Geosys.2, 2001GC000172) are an analytical artifact, rather than a true geochemical characteristic of loess because likely sources of loess are not significantly enriched in Ru and transport and deposition processes cannot preferentially enrich Ru in loess. The effect of eolian fractionation on PGE abundances in loess appears to be limited because Chinese loess from different locations shows similar PGE patterns and concentrations. This conclusion is supported by strong positive correlations between the PGE (except for Pt) and other compatible elements such as Fe2O3, Ni, Cr, Co. Using a compilation of PGE data for loess from China, Argentina and Europe, including our data but excluding one sample with an anomalously high Pt content, we propose average PGE abundances for global loess of Ir = 0.022 ppb (ng/g), Ru = 0.030 ppb, Rh = 0.018 ppb, Pt = 0.599 ppb, and Pd = 0.526 ppb, and suggest that these are the best current estimates for the PGE abundances of the UCC.

Park, Jung-Woo; Hu, Zhaochu; Gao, Shan; Campbell, Ian H.; Gong, Hujun

2012-09-01

241

2,2'-Bipyridine compounds of group 14 elements: a density functional theory study.  

PubMed

The molecular and electronic structures of the 2,2'-bipyridine containing series of group 14 compounds (a) [MF4(bpy)](0); (b) [MCl2(bpy)2](2+/0) (c) [MCl2(bpy)](0); (d) [M(bpy)2](2+/0); (e) [Si(bpy)3](1+,0,1-,2-); and (f) [M(bpy)3](0) (M = C, Si, Ge, Sn, Pb) have been calculated using density functional theory (DFT). Where possible, geometry optimized structures are compared with their experimentally determined structures. In general, good to excellent agreement is observed. It is shown that the three successive one-electron reductions within the experimentally known series [Si(bpy)3](1+,0,1-,2-) are ligand-based and the Si center has a +IV oxidation state throughout. Hence, these species have the electronic structures [Si(IV)(bpy(•))3](+) (S = 1/2), [Si(IV)(bpy(•))2(bpy(2-))](0) (S = 0), [Si(IV)(bpy(•))(bpy(2-))2](-) (S = 1/2), and [Si(IV)(bpy(2-))3](2-) (S = 0). Similarly, it is shown that the crystallographically characterized compound [Si(bpy)2](0) (S = 0) possesses the electronic structure [Si(IV)(bpy(2-))2](0), which contains a tetravalent Si ion and two (bpy(2-))(2-) dianions. It should not be described as [Si(0)(bpy(0))2](0). For the heavier Ge, Sn, and Pb congeners the divalent state, characterized by a stereochemically active electron pair, becomes increasingly significant and dominates in 4-coordinate Sn and Pb species. PMID:23931635

England, Jason; Wieghardt, Karl

2013-08-09

242

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

243

Relation between hydrogen embrittlement and the formation of hydride in the group V transition metals  

Microsoft Academic Search

The embrittlement of vanadium and tantalum by hydrogen has been investigated with the ultimate goal being to answer three\\u000a specific questions concerning ductility behavior in different temperature ranges. Torsion pendulum internal friction and another\\u000a technique using the torsion pendulum as well as visual observations have been used to establish the solid solubility curve\\u000a in the V-H and the Ta-H systems.

C. V. Owen; T. E. Scott

1972-01-01

244

Epizootic of Group B Streptococcus agalactiae Serotype V in DBA\\/2 Mice  

Microsoft Academic Search

1 Abstract Beta-hemolytic Streptococcus agalactiae serotype V was identified as the cause of an infec- tion in laboratory mice. Principally, the organism induced fatal septicemia in DBA\\/2 breeding-age mice. The syndrome appeared to originate as an ascending pyelonephritis, which progressed to septicemia. Microscopic lesions were found in the heart, kidneys, spleen, and liver, and less commonly in the uterus, thoracic

James G. Geistfeld; Steven H. Weisbroth; Elizabeth A. Jansen; Diane Kumpfmiller

1998-01-01

245

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, SPhT /CERN /Fermilab /INFN, Turin /Turin U. /Montreal U. /TRIUMF /Florida State U. /Argonne /Annecy, LAPTH /Paris, LPTHE /Moscow State U. /Cornell U., CIHEP /Delhi U. /Milan U. /INFN, Milan /Freiburg U. /Cadi Ayyad U., Marrakech /Orsay, LPT /Oslo U. /Lancaster U.

2006-03-17

246

Revised ab initio Natural Band Offsets of All Group IV, II-VI and III-V Semiconductors  

SciTech Connect

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

Li, Y. H.; Walsh, A.; Chen, S.; Yin, W. J.; Yang, J. H.; Li, J.; Da Silva, J. L. F.; Gong, X. G.; Wei, S. H.

2009-01-01

247

GROUP  

Microsoft Academic Search

In this paper we continue the study ofalg 1 (S) for minimal surfaces of general type S satisfying K2 S < 3?(S). We show that, if K 2 S = 3?(S) 1 and |?alg 1 (S)| = 8, then S is a Campedelli surface. In view of the results of (MP1) and (MP2), this implies that the fundamental group of

CIRO CILIBERTO; MARGARIDA MENDES LOPES; RITA PARDINI

248

Mineralogy and geochemistry of platinum-group elements in the Aguablanca Ni-Cu deposit (SW Spain)  

NASA Astrophysics Data System (ADS)

The Aguablanca Ni-Cu-(PGE) magmatic sulphide deposit is associated with a magmatic breccia located in the northern part of the Aguablanca gabbro (SW, Iberia). Three types of ores are present: semi-massive, disseminated, and chalcopyrite-rich veined ore. The principal ore minerals are pyrrhotite, pentlandite and chalcopyrite. A relatively abundant platinum-group mineral (PGM) assemblage is present and includes merenskyite, melonite, michenerite, moncheite and sperrylite. Moreover, concentrations of base and precious metals and micro-PIXE analyses were obtained for the three ore-types. The mineralogy and the mantle-normalised chalcophile element profiles strongly suggest that semi-massive ore represents mss crystallisation, whereas the disseminated ore represents an unfractionated sulphide liquid and the chalcopyrite-rich veined ore a Cu-rich sulphide liquid. Palladium-bearing minerals occur commonly enclosed within sulphides, indicating a magmatic origin rather than hydrothermal. The occurrences and the composition of these minerals suggest that Pd was initially dissolved in the sulphides and subsequently exsolved at low temperatures to form bismutotellurides. Negative Pt and Au anomalies in the mantle-normalised chalcophile element profiles, a lack of Cu-S correlation and textural observations (such as sperrylite losing its euhedral shape when in contact with altered minerals) suggest partial remobilisation of Pt, Au and Cu by postmagmatic hydrothermal fluids after the sulphide crystallisation.

Piña, R.; Gervilla, F.; Ortega, L.; Lunar, R.

2008-01-01

249

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

USGS Publications Warehouse

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

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

1997-01-01

250

Significant Li isotope fractionation in geochemically evolved rare element-bearing pegmatites from the Little Nahanni Pegmatite Group, NWT, Canada  

NASA Astrophysics Data System (ADS)

Lithium isotope signatures of whole rock pegmatite samples and mineral separates from the rare element-bearing Little Nahanni Pegmatite Group, NWT, and whole rock samples from nearby granitic intrusions were measured. Correlation of the Li isotopic values from the pegmatite dikes with whole rock trace element geochemistry, mineralogy and primary textural evidence reflect mechanisms of Li isotopic fractionation during pegmatite formation. The heavier ?7Li signatures within the broad range measured from whole rock LNPG samples (- 0.94‰ to + 11.36‰) are related to the consolidation of the final ~ 15% melt fraction of a volatile-rich peraluminous magma in the late stages of magmatic fractionation. Rock-forming minerals (quartz, albite, spodumene and mica) display ?7Li signatures that indicate consolidation of the dikes under variable, non-equilibrium conditions. Lithium isotope signatures of relatively cool, highly evolved peraluminous magmas reflect the build-up of fluxes (e.g., H2O and F) and provide a qualitative assessment of the state of mineral/melt chemical equilibrium.

Barnes, Elspeth M.; Weis, Dominique; Groat, Lee A.

2012-02-01

251

Alteration of platinum-group minerals and dispersion of platinum-group elements during progressive weathering of the Aguablanca Ni-Cu deposit, SW Spain  

NASA Astrophysics Data System (ADS)

The distribution, mineralogy and mobility of the platinum-group elements (PGE) in the surface environment are poorly understood. This study of the lower, less altered and upper, more altered gossan, overlying the Aguablanca Ni-Cu-(PGE) magmatic deposit (Spain), has shown that the platinum-group minerals (PGM) are progressively oxidised and dispersed into iron oxides that form the gossan. A combination of the characterization of PGE in host PGM, using a scanning electron microscope, and measurement of PGE at lower concentrations in host iron oxides, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), has for the first time allowed the total distribution of the PGE within a gossan to be documented. This study has revealed a complete in situ alteration and dispersion sequence of the PGM including (1) breakdown of both the more stable Pt-arsenides, Pt/Pd-tellurides and the less stable bismuthotellurides, (2) formation of partially oxidised PGM, (3) development of a wide range of oxidised Pt- and Pd-bearing phases, (4) subsequent formation of Fe-PGE-oxides and PGE-hydroxides, (5) incorporation of PGE into ferruginous supergene products and lastly (6) concentration of PGE at the edges of veins and iron oxides. Dispersion of Pd is greater than for the other PGE with Pd being widely distributed throughout the iron oxides. This oxidising environment produced PGE-oxides rather than PGE-alloys, also commonly found in the surface environment, especially in placers. These results provide critical evidence for the stages of mineralogical change from PGE host mineralogy in magmatic ores to surface weathering producing PGE-oxides.

Suárez, Saioa; Prichard, Hazel M.; Velasco, Francisco; Fisher, Peter C.; McDonald, Iain

2010-04-01

252

High-pressure structural trends of Group 15 elements: simple packed structures versus complex host-guest arrangements.  

PubMed

The Group 15 elements P, As, Sb, and Bi all have layered structures consisting of six-membered rings under ambient conditions and attain the body-centered cubic (bcc) structure at the highest pressures applied. In the intermediate pressure region, however, phosphorus and its heavier congeners behave profoundly differently. In this region P first attains the open packed simple cubic (sc) structure for a wide range of pressures and then transforms into the rarely observed simple hexagonal (sh) structure. For the heavier congeners complex, incommensurately modulated host-guest structures emerge as intermediate pressure structures. We investigated the high-pressure behavior of P and As by ab initio density functional calculations in which pseudopotentials and a plane wave basis set were employed. The incommensurately modulated high-pressure structure of As was approximated by a supercell. Our calculations reproduced the experimentally established pressure stability ranges of the sc and sh structures for P and the host-guest structure for As very well. We found that the sc and especially the sh structure are decisively stabilized by the admixture of d states in the occupied levels of the electronic structure. This admixture releases s-s antibonding states above the Fermi level (s-d mixing). With pressure, s-d mixing increases rapidly for P, whereas it remains at a low level for As. As a consequence, the band energy contribution to the total energy determines the structural stability for P in the intermediate pressure region, giving rise to simple packed structures. On the other hand, in the intermediate pressure region of the heavier Group 15 elements, a delicate interplay between the electrostatic Madelung energy and the band energy leads to the formation of complex structures. PMID:12658643

Häussermann, Ulrich

2003-04-01

253

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

254

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

PubMed Central

Vascular endothelial growth factor (VEGF) is a potent inducer of inflammation, and we have shown that this latter effect is mediated through endothelial cell (EC) PAF synthesis. Since the phospholipid remodelling pathway enzymes (CoA-independent transacylase, CoA-IT; phospholipase A2, PLA2; and lyso-PAF acetyltransferase, lyso-PAF-AT) may participate in PAF synthesis, we assessed their contribution to VEGF-induced PAF synthesis in bovine aortic EC (BAEC) and human umbilical vein EC (HUVEC).VEGF enhanced BAEC and HUVEC PAF synthesis by up to 28 and 4 fold above basal levels respectively.A pretreatment with a CoA-IT and lyso-PAF-AT inhibitor (Sanguinarin; 500?nM) blocked VEGF-induced PAF synthesis by 95%, a specific CoA-IT inhibitor (SKF45905; 10?–?50??M) was without effect, confirming the crucial role of the PLA2 and lyso-PAF-AT.Treatment with secreted PLA2 (sPLA2) inhibitors which have been shown to inhibit both groups IIA and V sPLA2 (SB203347; 10??M and LY311727; 100??M) blocked EC PAF synthesis by up to 90%, whereas selective inhibition of group IIA sPLA2 (LY311727; 1??M) had no significant effect.RT?–?PCR and Western blot analyses demonstrated the presence of group V sPLA2 whereas group IIA sPLA2 was undetected in EC.Treatment with cytosolic and calcium-independent PLA2 inhibitors (Arachidonyl trifluoromethyl ketone, Bromoenol lactone, Methyl arachydonyl fluorophosphate, up to 50??M) did not prevent but rather potentiated the VEGF effect on EC PAF synthesis.These results provide evidence that with VEGF activation of EC cells, the group V sPLA2 provides substrate for EC PAF formation.

Bernatchez, Pascal N; Winstead, Michelle V; Dennis, Edward A; Sirois, Martin G

2001-01-01

255

Glyceride studies. V. The distribution of unsaturated acyl groups in vegetable triglycerides  

Microsoft Academic Search

The distribution of oleic, linoleic, linolenic, petroselinic, hexadec-9 and 11-enoic, sterculic, four conjugated octadecatrienoic\\u000a acids, isolinolenic, and octadeca-6,9,12,15-tetraenoic acid in vegetable triglycerides has been studied by hydrolysis with\\u000a pancreatic lipase. The results, discussed in terms of a selectivity factor, indicate that these unsaturated acids do not compete\\u000a equally for the secondary hydroxyl group.

F. D. Gunstone; R. J. Hamilton; F. B. Padley; M. Ilyas Qureshi

1965-01-01

256

“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

257

Controls on Platinum-Group Element Abundances in 110 samples of Arc Lavas from the Southwest Pacific  

NASA Astrophysics Data System (ADS)

We present new data for platinum group element (PGE) concentrations in lavas of several types from the southwestern Pacific region. The suite includes potassic to ultrapotassic basalts from Mts Hagen and Bosavi in Papua New Guinea; arc picrites from New Georgia; boninites from Chichi Jima and from both the northern Tonga arc and its back-arc basin; basalts and andesites from the arc fronts and back arc basins of the New Hebrides and Tofua arcs. Based on variations in PGE concentrations and interelement ratios we suggest that it is possible to detect the retention of PGE in the source mantle by several different phases. In the presence of sulphide liquid, PGE concentrations are all diminished relative to Cu, Ni, and Au. When mss is present, a strong fractionation is evident between the IPGE (Ir, Ru, Rh), and the PPGE (Pt, Pd). These relationships are well known. However we also detect two other strong fractionations which we attribute to the presence of platinum group minerals in the source mantle. Depletions in Ir and Ru relative to Rh can be caused by the presence of either laurite (Ru,Ir)S2 or osmiridium alloy. The modal abundance of osmidirium alloy (or an equivalent amount of the same elements in the sulphide laurite) required to account for the observed depletions in Ir and Ru is on the order of one in 10^-08. Most notably in the Chichi Jima boninites, but also in those from the Tonga arc and back-arc, we observe distinct depletions in Pt that we also tentatively attribute to the presence of Pt-Fe alloy or intermetallic compounds in the source mantle. The inferred occurrence of coexisting mss and sulphide liquid is a universal feature of the back-arc rift and volcanic front samples, whereas the signature of restite platinum group minerals is generally restricted to magmas with extremely depleted source mantle (i.e., boninites). Systematic decreases in the concentrations of all PGE accompany magmatic evolution of all suites for which we have sufficient data. There is no evident relationship between the PGE depletion and the appearance or disappearance of any fractionating solids nor sulphide of liquid. We infer that the PGE are being lost to a vapour phase during rise and cooling of the magmas.

Mungall, J. E.; Karrei, L. I.; Arculus, R. J.; Mavrogenes, J.

2011-12-01

258

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

2010-10-01

259

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

260

Trace element (Al, As, B, Ba, Cr, Mo, Ni, Se, Sr, Tl, U and V) distribution and seasonality in compartments of the seagrass Cymodocea nodosa.  

PubMed

Novel information on the biological fate of trace elements in seagrass ecosystems is provided. Al, As, B, Ba, Cr, Mo, Ni, Se, Sr, Tl, U and V concentrations in five compartments (blades, sheaths, vertical rhizomes, main axis plus additional branches, roots) of the seagrass Cymodocea nodosa, as well as in seawater and sediments from the Thessaloniki Gulf, Greece were determined monthly. Uni- and multivariate data analyses were applied. Leaf compartments and roots displayed higher Al, Mo, Ni and Se annual mean concentrations than rhizomes, B was highly accumulated in blades and Cr in sheaths; As, Ba, Sr and Tl contents did not significantly vary among plant compartments. A review summarizing reported element concentrations in seagrasses has revealed that C. nodosa sheaths display a high Cr accumulation capacity. Most element concentrations in blades increased in early mid-summer and early autumn with blade size and age, while those in sheaths peaked in late spring-early summer and autumn when sheath size was the lowest; elevated element concentrations in seawater in late spring and early-mid autumn, possibly as a result of elevated rainfall and associated run-off from the land, may have also contributed to the observed variability. Element concentrations in rhizomes and roots generally displayed a temporary increase in late autumn, which was concurrent with high rainfall, low wind speed associated with reduced hydrodynamism, and elevated sediment element levels. The bioaccumulation factor based on element concentrations in seagrass compartments and sediments was lower than 1 except for B, Ba, Mo, Se and Sr in all compartments, Cr in sheaths and U in roots. Blade V concentration positively correlated with sediment V concentration, suggesting that C. nodosa could be regarded as a bioindicator for V. Our findings can contribute to the design of biomonitoring programs and the development of predictive models for rational management of seagrass meadows. PMID:23838054

Malea, Paraskevi; Kevrekidis, Theodoros

2013-07-06

261

Envelope Proteins of Vesicular Stomatitis Virus: Effect of Temperature-Sensitive Mutations in Complementation Groups III and V  

PubMed Central

All five major viral proteins were synthesized in chicken embryo cells infected with vesicular stomatitis virus temperature-sensitive (ts) mutants of complementation groups III and V and maintained at the nonpermissive temperature. The distribution of these proteins among cytoplasmic cellular fractions separated on discontinuous sucrose gradients was identical for wild-type and tsIII-infected cells. Strikingly different patterns were observed for the G protein in gradients from cells infected by tsV mutants; very little, if any, G protein was found in the lightest fraction. Pulse and chase experiments with wild-type, virus-infected cells showed that protein G moves from the heaviest to the lightest fraction before being incorporated into the virion. After shift down to the permissive temperature (30 C), G protein synthesized at 39.6 C in tsV-infected cells became associated with the lightest cellular fraction and later with the released virions. In contrast, M protein, synthesized at 39.6 C in tsIII-infected cells, was not incorporated into the virions after shift down. These data strongly suggest, first, that M protein is encoded by the vesicular stomatitis gene III, and second, that incorporation of G protein in the lightest cellular fraction is a necessary step of vesicular stomatitis maturation. This step is impaired by tsV mutations.

Lafay, Florence

1974-01-01

262

Non-chondritic platinum-group element ratios in oceanic mantle lithosphere: petrogenetic signature of melt percolation?  

NASA Astrophysics Data System (ADS)

The concentrations of the platinum-group elements (PGE) Ir, Ru, Pt and Pd were determined in 11 abyssal peridotites from ODP Sites 895 and 920, as well in six ultramafic rocks from the Horoman peridotite body, Japan, which is generally thought to represent former asthenospheric mantle. Individual oceanic peridotites from ODP drill cores are characterized by variable absolute and relative PGE abundances, but the average PGE concentrations of both ODP suites are very similar. This indicates that the distribution of the noble metals in the mantle is characterized by small-scale heterogeneity and large-scale homogeneity. The mean Ru/Ir and Pt/Ir ratios of all ODP peridotites are within 15% and 3%, respectively, of CI-chondritic values. These results are consistent with models that advocate that a late veneer of chondritic material provided the present PGE budget of the silicate Earth. The data are not reconcilable with the addition of a significant amount of differentiated outer core material to the upper mantle. Furthermore, the results of petrogenetic model calculations indicate that the addition of sulfides derived from percolating magmas may be responsible for the variable and generally suprachondritic Pd/Ir ratios observed in abyssal peridotites. Ultramafic rocks from the Horoman peridotite have PGE signatures distinct from abyssal peridotites: Pt/Ir and Pd/Ir are correlated with lithophile element concentrations such that the most fertile lherzolites are characterized by non-primitive PGE ratios. This indicates that processes more complex than simple in-situ melt extraction are required to produce the geochemical systematics, if the Horoman peridotite formed from asthenospheric mantle with chondritic relative PGE abundances. In this case, the PGE results can be explained by melt depletion accompanied or followed by mixing of depleted residues with sulfides, with or without the addition of basaltic melt.

Rehkämper, Mark; Halliday, A. N.; Alt, J.; Fitton, J. G.; Zipfel, J.; Takazawa, E.

1999-10-01

263

Platinum-group element systematics in Mid-Oceanic Ridge basaltic glasses from the Pacific, Atlantic, and Indian Oceans  

NASA Astrophysics Data System (ADS)

The concentrations of Ir, Ru, Pt and Pd have been determined in 29 Mid-Oceanic Ridge basaltic (MORB) glasses from the Pacific ( N = 7), the Atlantic ( N = 10) and the Indian ( N = 11) oceanic ridges and the Red Sea ( N = 1) spreading centers. The effect of sulfide segregation during magmatic differentiation has been discussed with sample suites deriving from parental melts produced by high (16%) and low (6%) degrees of partial melting, respectively. Both sample suites define positive and distinct covariation trends in platinum-group elements (PGE) vs. Ni binary plots. The high-degree melting suite displays, for a given Ni content, systematically higher PGE contents relative to the low-degree melting suite. The mass fraction of sulfide segregated during crystallization (X sulf), the achievement of equilibrium between sulfide melt and silicate melts (R eff), and the respective proportions between fractional and batch crystallization processes (S b) are key parameters for modeling the PGE partitioning behavior during S-saturated MORB differentiation. Regardless of the model chosen, similar sulfide melt/silicate melt partition coefficients for Ir, Ru, Pt and Pd are needed to model the sulfide segregation process, in agreement with experimental data. When corrected for the effect of magmatic differentiation, the PGE data display coherent variations with partial melting degrees. Iridium, Ru and Pt are found to be compatible in nonsulfide minerals whereas the Pd behaves as a purely chalcophile element. The calculated partition coefficients between mantle sulfides and silicate melts (assuming a PGE concentration in the oceanic mantle at ˜0.007 × CI-chondritic abundances) increase from Pd (˜10 3) to Ir (˜10 5). This contrasting behavior of PGE during S-saturated magmatic differentiation and mantle melting processes can be accounted for by assuming that Monosufide Solid Solution (Mss) controls the PGE budget in MORB melting residues whereas MORB differentiation processes involve Cu-Ni-rich sulfide melt segregation.

Bézos, A.; Lorand, J.-P.; Humler, E.; Gros, M.

2005-05-01

264

X-box-binding proteins positively and negatively regulate transcription of the HLA-DRA gene through interaction with discrete upstream W and V elements.  

PubMed Central

Previous reports have identified that the class II box, consisting of the positive regulatory X and Y boxes, is important for expression of all class II major histocompatibility genes. In this paper, we identify additional sequences upstream from the class II box that regulate constitutive transcription of a human class II gene, HLA-DRA, in the B-lymphoblastoid cell line Raji. Using 5' promoter deletions, substitution mutants, and nuclease S1 protection assays, we mapped a positive element, called W, between -135 and -117 base pairs and a negative element, called V, from -193 to -179 base pairs. Sequence comparisons revealed that W and V share homology with the HLA-DRA X box situated downstream. Gel-mobility-shift assays confirmed that the Raji nuclear proteins that bound to W and V elements were competed with by an HLA-DRA X-box oligonucleotide. These results suggest that X-box-binding proteins mediate both positive and negative effects on transcription by means of interaction with multiple elements (W, V, and X) within the same HLA-DRA gene. Images

Cogswell, J P; Basta, P V; Ting, J P

1990-01-01

265

X-box-binding proteins positively and negatively regulate transcription of the HLA-DRA gene through interaction with discrete upstream W and V elements.  

PubMed

Previous reports have identified that the class II box, consisting of the positive regulatory X and Y boxes, is important for expression of all class II major histocompatibility genes. In this paper, we identify additional sequences upstream from the class II box that regulate constitutive transcription of a human class II gene, HLA-DRA, in the B-lymphoblastoid cell line Raji. Using 5' promoter deletions, substitution mutants, and nuclease S1 protection assays, we mapped a positive element, called W, between -135 and -117 base pairs and a negative element, called V, from -193 to -179 base pairs. Sequence comparisons revealed that W and V share homology with the HLA-DRA X box situated downstream. Gel-mobility-shift assays confirmed that the Raji nuclear proteins that bound to W and V elements were competed with by an HLA-DRA X-box oligonucleotide. These results suggest that X-box-binding proteins mediate both positive and negative effects on transcription by means of interaction with multiple elements (W, V, and X) within the same HLA-DRA gene. PMID:2120707

Cogswell, J P; Basta, P V; Ting, J P

1990-10-01

266

Study by Simulation with 1 MeV Electrons of the Effect of Minor Elements on the Swelling of Austenitic Alloys.  

National Technical Information Service (NTIS)

In this work, we describe the effect of minor elements (silicon, germanium, tin and antimony) on the swelling behaviour of a ''pure'' alloy (Fe-15Cr-20Ni) and of a commercial alloy (AISI 316) irradiated with 1 MeV electrons. The alloys in solution-anneale...

P. Dubuisson

1986-01-01

267

Continuing optical spectroscopy of V339 Del = Nova Del 2013 with the Nordic Optical Telescope and the ARAS Group  

NASA Astrophysics Data System (ADS)

Since our first report (ATel#5312) we have been continuing nightly, almost hourly spectroscopic observations of V339 Del = Nova Del 2013 = PNV J20233073+2046041). Here we report the state at approximately the t_3 point in the photometric decline (see also ATel#5370). Spectra have been obtained with the 2.6 m Nordic Optical Telecope FIbre-fed Echelle Spectrograph (FIES) (R ~ 67000), the Ondrejov Observatory 2m Zeiss coude spectrograph (R = 18000), and a variety of grating and echelle spectrographs of the ARAS group with resolutions ranging from 580 - 11000.

Shore, S. N.; Alton, K.; Antao, D.; Barbotin, E.; Berardi, P.; Bohlsen, P.; Boubault, F.; Boyd, D.; Briol, J.; Buil, C.; Charbonnel, S.; Dubreuil, P.; Dubs, M.; Edlin, J.; de France, T.; Favaro, A.; Garde, O.; Graham, K.; Greenan, D.; Guarro, J.; Hansen, T.; Hyde, D.; Lemoult, T.; Leadbeater, R.; Martineau, G.; Buchet, Y.; Masviel, J. P.; Montier, J.; Pollmann, E.; Ribeiro, J.; Thizy, O.; Terry, J.-N.; Teyssier, F.

2013-09-01

268

Kr and Xe ions implanted on the surfaces of Mo, Hf, Ta, W, Re, Au and platinum group elements  

NASA Astrophysics Data System (ADS)

Kr and Xe ion bombardment experiments were conducted on Mo, Hf, Ta, W, Re, Au, and five platinum group elements. The implanted Kr and Xe ions were detected, and their concentrations were determined by X-ray photoelectron spectroscopy (XPS) using synchrotron radiation. In the case of 5d transition metals, the binding energies of Kr2p3/2, Xe3d3/2, and Xe3d5/2 in the target metals correlate with the number of d electrons of metals. Furthermore, the Xe concentration in the 5d transition metals correlates with atomic number, but there is no such correlation for Kr. The observed trend for the Xe concentration can approximately be reproduced by a theoretical calculation that takes sputtering yield into consideration. The retentivities of Kr and Xe are defined as the ratio of the experimental and theoretical surface concentrations. Although there is no correlation between retentivity and the atomic number of the target metal, the elastic energies in the cases of Kr and Xe atoms implanted in metals positively correlate with the corresponding retentivities. If the activation energy of noble-gas diffusion in the target metals can be represented in terms of the elastic energy, the noble-gas retentivity can be qualitatively explained.

Osawa, Takahito

2012-03-01

269

Partitioning of platinum-group elements in the Fe-Ni-S system and their fractionation in nature  

SciTech Connect

The partitioning of minor amounts of platinum-group elements (PGEs: Ru, Rh, Pd, Os, Ir, and Pt) has been investigated in the Fe-Ni-S system at 1,000 to 1,400{degree}C and low pressure. Revising previous experimental results indicating lack of specificity of PGE, distinctly different partitioning behavior is demonstrated for heavy and light platinoids; Os, Ir, and Pt are preferentially concentrated in alloy phases, whereas Pd is depleted in alloys and relatively enriched in sulfide liquid. Partition coefficients for Fe alloy/sulfide liquid at 1,000{degree}C are 1 to 2 for Pd, 30 to 110 for Rh, and in excess of 1,000 for Os, Ir, and Pt. Ruthenium and, to a lesser extent, rhodium are the only PGEs with significant solubility in troilite coexisting with sulfide liquid. The marked fractionation of Pt from Pd in the presence of coexisting alloy and sulfide liquid is contrasted with the minimal fractionation of PGEs in the primary differentiation of planetary material and of Pt from Pd in the generation of basic magmas in the upper mantle. The characteristic fractionation patterns for PGEs in upper mantle and crustal rocks are most likely related to the presence of a combination of host phases for the refractory PGEs (Os, Ir, and Ru) during partial melting in the upper mantle.

Fleet, M.E. (Univ. of Western Ontario, London (Canada)); Stone, W.E. (McMaster Univ., Hamilton, Ontario (Canada))

1991-01-01

270

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

271

v-src Induction of the TIS10/PGS2 prostaglandin synthase gene is mediated by an ATF/CRE transcription response element  

SciTech Connect

The authors recently reported the cloning of a mitogen-inducible prostaglandin synthase gene, TIS10/PGS2. In addition to growth factor and tumor promoters, the v-src oncogene induces TIS10/PGS2 expression in 3T3 cells. Deletion analysis, using luciferase reporters, identifies a region between -80 and -40 nucleotides 5{prime} of the TIS10/PGS2 transcription start site that mediates pp60{sup v-src} induction in 3T3 cells. This region contains the sequence CGTCACGTG, which includes overlapping ATF/CRE (CGTCA) and E-box (CACGTG) sequences. Gel shift-oligonucleotide competition experiments with nuclear extracts from cells stably transfected with a temperature-sensitive v-src gene demonstrate that the CGTCACGTG sequence can bind proteins at both the AFT/CRE and E-box sequences. Dominant-negative CREB and Myc proteins that bind DNA, but do not transactivate, block v-src induction of a luciferase reporter driven by the first 80 nucleotides of the TIS10/PGS2 promoter. Mutational analysis distinguishes which TIS10/PGS2 cis-acting element mediates pp60{sup v-src} induction. E-box mutation has no effect on the fold induction in response to pp60{sup v-src}. In contrast, ATF/CRE mutation attenuates the pp{sup v-src} response. Antibody supershift and methylation interference experiments demonstrate that CREB and at least one other ATF transcription factor in these extracts bind to the TIS10/PGS2 ATF/CRE element. Expression of a dominant-negative ras gene also blocks TIS10/PGS2 induction by v-src. The data suggest that Ras mediates pp60{sup v-src} activation of an ATF transcription factor, leading to induced TIS10/PGS2 expression via the ATF/CRE element of the TIS10/PGS2 promoter. This is the first description of v-src activation of gene expression via an ATF/CRE element. 64 refs., 8 figs.

Xie, W.; Fletcher, B.S.; Andersen, R.D.; Herschman, H.R. [Univ. of California, Los Angeles, CA (United States)

1994-10-01

272

Adsorption of V-group elements and oxygen on Si( 0 0 1 )2×1 surface  

Microsoft Academic Search

The influence of atomic oxygen on the Si(001)\\/As, Si(001)\\/Sb and Si(001)\\/Bi surfaces has been investigated by MNDO-PM3 semiempirical method. The potential energy surfaces for atomic oxygen adsorbed on ideal Si(001)\\/M-(1 ML) surface (where M=As, Sb and Bi) have been calculated. Three equilibrium binding sites have been found for atomic oxygen adsorption with the formation of M–O–M, M–O–Si and Si–O–Si bridge

T. V. Afanasieva; I. F. Koval; N. G. Nakhodkin

2002-01-01

273

Roadside Accumulation of Pt, Pd, Rh and Other Trace Elements From Automobiles: Catalytic Converter Attrition and Platinum-Group Element Mobility in the Roadside Environment.  

NASA Astrophysics Data System (ADS)

Elemental abundances of Pt, Pd and Rh have been documented across the industrialized world in roadside environments due to attrition of automotive catalytic converters (Zereini and Alt, 2000, Anthropogenic PGE Emissions, Springer, 308pp; Ely et al., 2001, EnvSci&Tech, 35:3816-3822; Whiteley and Murray, 2003, SciTotEnv, in press). In our ongoing study, the highest reported roadside Pt abundance 1.8 ppm has been found immediately adjacent to the road at a field site in South Bend, IN, USA. Furthermore, initial studies show positive correlations of Pt, Pd and Rh with some trace elements (Ni, Cu, Zn and Pb), which has been confirmed by further analysis for these and other elements (Ce, Cr). It has been demonstrated that elements such as Ce are present in catalytic converters at concentrations of 100's ppm to 3-wt.%. These elements are also being attrited with Pt, Pd and Rh and aerially transported and deposited. Our field site was established next to US-933 adjacent to the Notre Dame campus. Areas were cleared of the top 2-4 cm of soil (removing surficial Pt, Pd and Rh) at 1, 5, 10 and 50 meters from the roadside. Within 3 months the 1-meter site contained 67% of the initial Rh and Pt concentrations and 100% of the initial Pd concentration. The sites at 5, 10 and 50 meters showed similar results, in some cases exceeding the initial concentrations. After 6 months the concentrations of Pt, Pd and Rh were all within error of the initial concentrations, indicating steady state abundances had probably been reached. Grass samples from each site showed that washed vs. unwashed samples were within error of each other, and there may be a slight enrichment (approx. 1 ppb) in the grasses of Pd and Pt, but this enrichment was independent of distance from the road. The steady-state situation suggests that the PGEs are being removed from the immediate roadside environment, which requires that the metals are being oxidized and/or complexed in such a way to facilitate transport. The environmental effects of such processes are unknown, but Pt complexes are known carcinogens. Electron microprobe and SEM analysis are being used to isolate particles using these surrogate trace elements in an ongoing effort to determine the oxidation state (using XANES) of Pt, Pd and Rh in the natural environment.

Ely, J. C.; Dahlheimer, S. R.; Neal, C. R.

2003-12-01

274

Differential elastic scattering cross sections of 22.1-keV x rays by elements in the range 22<=Z<=82  

NASA Astrophysics Data System (ADS)

Elastic scattering cross sections of 22.1-keV x rays by the elements Ti, V, Fe, Ni, Cu, Zn, Zr, Nb, Mo, Pd, Cd, In, Sn, Sm, Gd, Dy, Er, Yb, Au, and Pb have been measured at 90° with an overall error of 8-10 %. The 22.1-keV x rays were obtained from a Ag foil used as a secondary target in an x-ray fluorescence setup. Experimental cross sections have been compared with the nonrelativistic form factors (NFF), relativistic form factors, modified relativistic form factor (MRFF), relativistic form factor with anomalous scattering correction (RFFASF), modified relativistic form factor with anomalous scattering correction (MRFFASF), and the S matrix calculations. For low Z elements, experimental values are better represented by S matrix, RFFASF, and MRFFASF. For the elements Nb, Mo, and Pd whose K shell binding energies are very close to the exciting energy, the data are higher than all of the theoretical predictions. For higher Z elements, NFF and MRFF give a better agreement with the present data.

Mandal, A. C.; Mitra, D.; Sarkar, M.; Bhattacharya, D.

2002-10-01

275

Platinum-Group Element Variations in Hawaiian Lavas: Constraints on the Role of Sulfides during Melt Generation and Fractional Crystallization  

NASA Astrophysics Data System (ADS)

Platinum-group elements (PGE) are highly compatible in mantle and magmatic sulfides, with sulfide melt/silicate melt partition coefficients typically on the order of 104 or higher. PGE abundances in basaltic melts are therefore very sensitive to the presence or absence of residual sulfides during melt generation and the fractionation of magmatic sulfides during crystallization. PGE abundances (Ir, Os, Ru, Pt, Pd) were measured in lavas from Mauna Kea and Koolau volcanoes, Hawaiian Islands to constrain the abundance of residual sulfide in the Hawaiian plume during melt generation as well as the role of sulfide fractionation during melt evolution. Iridium, Os, and Ru are positively correlated with MgO content in lavas ranging from ˜6-28 wt.% MgO. Bulk partition coefficients during fractional crystallization range from ˜4 (Ir) to ˜7 (Os). The compatible behavior of Ir, Os and Ru in Hawaiian melts likely reflects the high compatibility of these elements in Cr-spinel, which coprecipitates with olivine in most Hawaiian lavas. In contrast, no significant trend is observed in Pt or Pd abundances with MgO content, indicating bulk partition coefficients for these elements of ˜1. Pt and Pd are predicted to be incompatible in Cr-spinels, but are highly compatible in magmatic sulfides (Dsulfide/silicate = 4.5x104) . The low bulk partition coefficients for Pt and Pd in the Koolau and Mauna Kea lavas indicate that sulfide segregation was insignificant during fractional crystallization, even in lavas that have experienced up to 25% olivine fractionation. Lack of sulfide saturation/segregation could reflect sulfur degassing in shallow magma chambers. However, deep submarine lavas from the HSDP-2 Mauna Kea drillcore display similar PGE trends. Therefore, it is likely that primary Hawaiian magmas (with ˜15-16 wt.% MgO) are at least ˜20-25% sulfur undersaturated when they reach crustal levels. If the source of Hawaiian lavas contains residual sulfide, primary Hawaiian melts should be sulfur-saturated at their depth of origin. However, because sulfur solubility increases with decreasing pressure, sulfur-saturated melts generated at depth become undersaturated as they rise, provided they do not reequilibrate with sulfide-bearing mantle during ascent. Sulfur undersaturation in primary Hawaiian lavas thus precludes significant interaction with the oceanic lithosphere during magma ascent. Bulk partition coefficients for the PGEs during melt generation are constrained from the PGE abundances in primitive Hawaiian lavas assuming primitive mantle abundances in the Hawaiian plume. Bulk partition coefficients during melt generation are higher than those for fractional crystallization, ranging from ˜3.5 (Pt) to 14 (Ir). Significantly, MgO-Ir, -Ru, and -Os trends are identical in the Koolau and Mauna Kea lavas, suggesting similar PGE and sulfide abundances in the sources of these two suites. Based on available sulfide/basalt PGE partition data, the bulk partition coefficients for melt generation are consistent with no more than ˜100-150 ppm residual sulfide ( ˜30-50 ppm sulfur) in the Hawaiian plume. If primary Hawaiian melts are generated by ˜5% partial melting and contain ˜1000 ppm sulfur, this suggests a sulfur content in the plume prior to melting of ˜100 ppm, significantly less than the sulfur content of primitive mantle. Low sulfur abundances in the plume may reflect the presence of significant quantities of recycled oceanic crust and lithospheric mantle that have had volatile species removed during subduction-induced dehydration.

Lassiter, J. C.

2003-12-01

276

Biallelic Mutations in PLA2G5, Encoding Group V Phospholipase A2, Cause Benign Fleck Retina  

PubMed Central

Flecked-retina syndromes, including fundus flavimaculatus, fundus albipunctatus, and benign fleck retina, comprise a group of disorders with widespread or limited distribution of yellow-white retinal lesions of various sizes and configurations. Three siblings who have benign fleck retina and were born to consanguineous parents are the basis of this report. A combination of homozygosity mapping and exome sequencing helped to identify a homozygous missense mutation, c.133G>T (p.Gly45Cys), in PLA2G5, a gene encoding a secreted phospholipase (group V phospholipase A2). A screen of a further four unrelated individuals with benign fleck retina detected biallelic variants in the same gene in three patients. In contrast, no loss of function or common (minor-allele frequency>0.05%) nonsynonymous PLA2G5 variants have been previously reported (EVS, dbSNP, 1000 Genomes Project) or were detected in an internal database of 224 exomes (from subjects with adult onset neurodegenerative disease and without a diagnosis of ophthalmic disease). All seven affected individuals had fundoscopic features compatible with those previously described in benign fleck retina and no visual or electrophysiological deficits. No medical history of major illness was reported. Levels of low-density lipoprotein were mildly elevated in two patients. Optical coherence tomography and fundus autofluorescence findings suggest that group V phospholipase A2 plays a role in the phagocytosis of photoreceptor outer-segment discs by the retinal pigment epithelium. Surprisingly, immunohistochemical staining of human retinal tissue revealed localization of the protein predominantly in the inner and outer plexiform layers.

Sergouniotis, Panagiotis I.; Davidson, Alice E.; Mackay, Donna S.; Lenassi, Eva; Li, Zheng; Robson, Anthony G.; Yang, Xu; Kam, Jaimie Hoh; Isaacs, Timothy W.; Holder, Graham E.; Jeffery, Glen; Beck, Jonathan A.; Moore, Anthony T.; Plagnol, Vincent; Webster, Andrew R.

2011-01-01

277

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

NASA Astrophysics Data System (ADS)

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 (Hf), 1.07 (Ta), 1.05 (W), 1.05 (Re), 1.05 (Pt), and 0.96 (Au) to the commonly used empirical electronic stopping power by Ziegler, Biersack, and Littmark were determined to an accuracy of +/-5%. At velocities v<2v0, much higher electronic stopping power and different velocity dependence than predicted by the empirical model were obtained. The electronic stopping power was determined to an accuracy of +/-5%. The reduction of the nuclear stopping power due to the polycrystalline structure of the slowing-down materials was taken into account in the deduction of the electronic stopping power.

Arstila, K.; Keinonen, J.; Tikkanen, P.

1990-04-01

278

Stopping power for low-velocity heavy ions: (0--1. 0)-MeV/nucleon Mg ions in 17 ( Z =22--79) elemental solids  

SciTech Connect

The stopping power for {sup 24,26}Mg ions in 17 ({ital 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 2{ital v}{sub 0}{lt}{ital v}{lt}5{ital v}{sub 0} ({ital v}{sub 0} 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 (Hf), 1.07 (Ta), 1.05 (W), 1.05 (Re), 1.05 (Pt), and 0.96 (Au) to the commonly used empirical electronic stopping power by Ziegler, Biersack, and Littmark were determined to an accuracy of {plus minus}5%. At velocities {ital v}{lt}2{ital v}{sub 0}, much higher electronic stopping power and different velocity dependence than predicted by the empirical model were obtained. The electronic stopping power was determined to an accuracy of {plus minus}5%. The reduction of the nuclear stopping power due to the polycrystalline structure of the slowing-down materials was taken into account in the deduction of the electronic stopping power.

Arstila, K.; Keinonen, J.; Tikkanen, P. (Accelerator Laboratory, University of Helsinki, Haemeentie 100, SF-00550 Helsinki, Finland (FI))

1990-04-01

279

Platinum-group elements (Rh, Pt, Pd) and Au distribution in snow samples from the Kola Peninsula, NW Russia  

NASA Astrophysics Data System (ADS)

In April 1996 snowpack samples were collected from the surroundings of the ore roasting and dressing plant at Zapoljarnij and the nickel smelters at Nikel and Monchegorsk, Kola Peninsula, NW Russia. In the laboratory, filter residues of snowpack samples (fraction>0.45 ?m) from 15 localities (close to the nickel processing centres) were chemically for precious metals (Rh, Pt, Pd, Au) and Te by graphite furnace atomic absorption spectrometry (GFAAS) analysis, and for Cu and Ni by ICP-MS. Values up to 2770 ng/l Pd, 650 ng/l Pt and 186 ng/l Au were found in the filter residues. Additionally, platinum-group elements (PGE) and Au contents in ore samples from Noril'sk , as well as in technogenic products ("Cu-Ni-feinstein" and copper concentrate) processed at the Monchegorsk smelter complex, were analysed using flameless atomic absorption spectroscopy (FAAS) for comparison with results obtained from snow. Rh, Pt, Pd and Au distribution data show the presence of two ore components (Noril'sk and Pechenga). Concentrations of these metals decrease with distance from the industrial sources and with the prevailing wind direction (generally north-south). Microscopic investigations and electron microprobe analysis of polished sections of snow filter residues (>0.45 ?m) also reveal differences between particles from the two sources. To avoid confusion the term "Noril'sk" is used throughout the paper to denote material and/or data from the Noril'sk area and its sub-district, Noril'sk while Pechenga relates to the local ore.

Gregurek, Dean; Melcher, Frank; Niskavaara, Heikki; Pavlov, Vladimir A.; Reimann, Clemens; Stumpfl, Eugen F.

280

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

281

Influences of additional alloying elements (V, Ni, Cu, Sn, B) on structure and mechanical properties of high-strength hypereutectic Ti–Fe–Co bulk alloys  

Microsoft Academic Search

High-strength nonequilibrium hypereutectic bulk alloys were obtained recently in the Ti–Fe and Ti–Fe–Co systems by arc-melting. Following these results, the influences of the additional alloying elements (V, Ni, Cu, Sn, B) on high strength hypereutectic Ti–Fe–Co bulk alloys are studied and analyzed in the present work. The structure of the hypereutectic quaternary Ti67Fe14Co14Sn5, Ti67Fe14Co14V5, Ti70Fe17Co7Cu6, Ti70Fe17Co7Ni6, and Ti69.4Fe14.8Co14.8B1 alloys obtained

Larissa V. Louzguina-Luzgina; Dmitri V. Louzguine-Luzgin; Akihisa Inoue

2006-01-01

282

Evidence from meimechites and other low-degree mantle melts for redox controls on mantle-crust fractionation of platinum-group elements  

PubMed Central

Understanding of the geochemistry of the chalcophile elements [i.e., Os, Ir, Ru, Pt, Pd (platinum-group elements), and Au, Cu, Ni] has been informed for at least 20 years by the common assumption that when crust-forming partial melts are extracted from the upper mantle, sulfide liquid in the restite sequesters chalcophile elements until the extent of partial melting exceeds ?25% and all of the sulfide has been dissolved in silicate melt [Hamlyn, P. R. & Keays, R. R. (1985) Geochim. Cosmochim. Acta 49, 1797–1811]. Here we document very high, unfractionated, chalcophile element concentrations in small-degree partial melts from the mantle that cannot be reconciled with the canonical residual sulfide assumption. We show that the observed high, unfractionated platinum-group element concentrations in small-degree partial melts can be attained if the melting takes place at moderately high oxygen fugacity, which will reduce the amount of sulfide due to the formation of sulfate and will also destabilize residual monosulfide solid solution by driving sulfide melts into the spinel-liquid divariant field. Magmas formed at high oxygen fugacity by small degrees of mantle melting can be important agents for the transfer of chalcophile elements from the upper mantle to the crust and may be progenitors of significant ore deposits of Pt, Pd, and Au.

Mungall, James E.; Hanley, Jacob J.; Arndt, Nicholas T.; Debecdelievre, Anne

2006-01-01

283

Les Houches ''Physics at TeV Colliders 2003'' 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, 26 May-6 June, 2003. The research presented is original, and was performed specifically for the workshop. Tools for calculations in the minimal supersymmetric standard model are presented, including a comparison of the dark matter relic density predicted by public codes. Reconstruction of supersymmetric particle masses at the LHC and a future linear collider facility is examined. Less orthodox supersymmetric signals such as non-pointing photons and R-parity violating signals are studied. Features of extra dimensional models are examined next, including measurement strategies for radions and Higgs', as well as the virtual effects of Kaluza Klein modes of gluons. Finally, there is an update on LHC Z' studies.

Allanach, B

2004-03-01

284

Proton Inelastic Mean Free Path in a Group of Organic Materials in 0.05-10 MeV Range  

NASA Astrophysics Data System (ADS)

Inelastic mean free paths (MFPs) of 0.05-10 MeV protons in a group of 10 organic compounds are systematically calculated. The calculations are based on the method newly derived from the Ashley optical-data model and from the higher-order correction terms in stopping power calculations. Especially, in this method the new and empirical Bloch correction for the inelastic MFP is given. An evaluation for the optical energy loss function is incorporated into the present calculations because of the lack of available experimental optical data for the considered organic compounds expect for kapton. The proton inelastic MFPs for these 10 organic compounds in the energy range from 0.05 to 10 MeV are presented here for the first time, and the combination of these inelastic MFP data and our previous data of stopping power calculation for these bioorganic compounds may form a useful database for Monte Carlo track-structure studies of various radiation effects on these materials.

Tan, Zhen-Yu; Xia, Yue-Yuan; Zhao, Ming-Wen; Liu, Xiang-Dong

2010-11-01

285

Cooperating Teachers' Perceptions of Important Elements of the Student Teaching Experience: A Focus Group Approach with Quantitative Follow-up  

Microsoft Academic Search

Two purposes of this study were to describe selected characteristics of cooperating teachers\\/ schools and to identify teachers' perceptions about important elements of student teaching. Some researchers contend that to better understand complex phenomena, a \\

M. Craig Edwards; Gary E. Briers

2001-01-01

286

Influence of the elemental composition and crystal structure on the vacuum properties of Ti-Zr-V non-evaporable getter films  

Microsoft Academic Search

Non-evaporable thin film getters based on the elements of the 4th and 5th columns of the periodic table have been deposited by sputtering. Among the about 20 alloys studied to date, the lowest activation temperature (about 180 °C for a 24-hour heating) has been found for the Ti-Zr-V system in a well-defined composition range. The characterization of the activation behavior

A E Prodromides; Cristoforo Benvenuti; P Chiggiato; A Mongelluzzo; V Ruzinov; C Scheuerlein; M Taborelli; F Lévy

2001-01-01

287

Measurement of K-L radiative vacancy transfer probabilities in selected rare earth elements bombarded with 3-4 MeV protons  

NASA Astrophysics Data System (ADS)

K-shell X-ray intensity ratios for selected rare earth elements were measured following irradiation with proton beams having energies between 3 and 4 MeV. Using the X-ray intensity ratios, the radiative vacancy transfer probabilities from the shell K to the L sub-shells were determined. The experimental data were compared to theoretical predictions for X-ray line intensities and radiative vacancy transfer probabilities. The results showed a good agreement between theory and experiment.

Reyes-Herrera, J.; Miranda, J.

2008-12-01

288

Measurement of 14 MeV neutron-induced prompt gamma-ray spectra from 15 elements found in cargo containers  

Microsoft Academic Search

Within the EURopean Illicit TRAfficking Countermeasures Kit (EURITRACK) project, the gamma-ray spectra produced in a series of materials by 14-MeV tagged-neutron beams have been collected in the inspection portal equipped with large volume NaI(Tl) detectors, in order to build a database of signatures for various elements: C, N, O, Na, Al, Si, Cl, K, Ca, Cr, Fe, Ni, Cu, Zn,

B. Perot; C. Carasco; S. Bernard; A. Mariani; J.-L. Szabo; G. Sannie; V. Valkovic; D. Sudac; G. Viesti; M. Lunardon; C. Botosso; G. Nebbia; S. Pesente; S. Moretto; A. Zenoni; A. Donzella; M. Moszynski; M. Gierlik; W. Klamra; P. Le Tourneur; M. Lhuissier; A. Colonna; C. Tintori; P. Peerani; V. Sequeira; M. Salvato

2008-01-01

289

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

Microsoft Academic Search

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

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

1972-01-01

290

A Divergent P Element and Its Associated MITE, BuT5, Generate Chromosomal Inversions and Are Widespread within the Drosophila repleta Species Group  

PubMed Central

The transposon BuT5 caused two chromosomal inversions fixed in two Drosophila species of the repleta group, D. mojavensis and D. uniseta. BuT5 copies are approximately 1-kb long, lack any coding capacity, and do not resemble any other transposable element (TE). Because of its elusive features, BuT5 has remained unclassified to date. To fully characterize BuT5, we carried out bioinformatic similarity searches in available sequenced genomes, including 21 Drosophila species. Significant hits were only recovered for D. mojavensis genome, where 48 copies were retrieved, 22 of them approximately 1-kb long. Polymerase chain reaction (PCR) and dot blot analyses on 54 Drosophila species showed that BuT5 is homogeneous in size and has a widespread distribution within the repleta group. Thus, BuT5 can be considered as a miniature inverted-repeat TE. A detailed analysis of the BuT5 hits in D. mojavensis revealed three partial copies of a transposon with ends very similar to BuT5 and a P-element-like transposase-encoding region in between. A putatively autonomous copy of this P element was isolated by PCR from D. buzzatii. This copy is 3,386-bp long and possesses a seven-exon gene coding for an 822-aa transposase. Exon–intron boundaries were confirmed by reverse transcriptase-PCR experiments. A phylogenetic tree built with insect P superfamily transposases showed that the D. buzzatii P element belongs to an early diverging lineage within the P-element family. This divergent P element is likely the master transposon mobilizing BuT5. The BuT5/P element partnership probably dates back approximately 16 Ma and is the ultimate responsible for the generation of the two chromosomal inversions in the Drosophila repleta species group.

Rius, Nuria; Delprat, Alejandra; Ruiz, Alfredo

2013-01-01

291

Particle-hole formulation of the unitary group approach to the many-electron correlation problem. II. Matrix element evaluation  

Microsoft Academic Search

Graphical methods of spin algebras are used to derive the expressions for the matrix elements of the total particle-number-conserving operators in the basis of hole-particle states, adapted to the chain U(n'+n'')?U(n')?U(n''), where n' and n'' designate dimensions of particle and hole subspaces, respectively. The matrix elements are expressed as a product of segment values, each associated with one orbital level

M. J. Boyle; J. Paldus

1980-01-01

292

Randomized evaluation of benzathine penicillin V twice daily versus potassium penicillin V three times daily in the treatment of group A streptococcal pharyngitis  

Microsoft Academic Search

In a randomized, prospective, multicenter study the clinical and bacteriological efficacies of three dosage schedules with two different salts of oral penicillin V suspensions (regimen 1: potassium salt of penicillin V, 50,000 U\\/kg of body weight per day in three divided doses; regimen 2: benzathine salt of penicillin V, 50,000 U\\/kg of body weight per day in two divided doses;

A. Kaufhold

1995-01-01

293

Air Conditioner Requirements Validation Review of the Divarty Computer Group of the Fire Direction Center, Artillery (OL-48B/GSB10(V)), or TACFIRE.  

National Technical Information Service (NTIS)

This report assesses the tactical electric power and cooling requirements of the TACFIRE DIVARTY Computer Group, AN/GSG-10(V), for the 'Air Conditioner Requirements Review Program.' System Assessment Model (SAM) Environmental Control Unit (ECU).

G. F. Brainard A. A. Thompson J. P. Lucas

1992-01-01

294

Determination of Mutually Interfering Elements in Activation Analysis. Study of the Groups As-Sb-Br, Se-Hg and Sc-ZN.  

National Technical Information Service (NTIS)

The determination of the elements present in the groups scandium-zinc, mercury-selenium and arsenic-antimony-bromine represents a classical problem in thermal neutron activation analysis because the gamma-ray peaks of the radioisotopes produced from these...

A. M. G. Figueiredo

1979-01-01

295

Determination of gold and the platinum group elements in geological samples by ICP-MS after nickel sulphide fire assay: difficulties encountered with different types of geological samples  

Microsoft Academic Search

Problems involved in the determination of Au and the platinum group elements by the nickel sulphide fire assay (NiS-FA) procedure for black shale samples, samples containing magnetite, and samples containing As, Cu, and Fe were studied. The interference of the graphite in black shale samples was eliminated either by roasting the sample prior to fusion or by adding an oxidant

R Juvonen; T Lakomaa; L Soikkeli

2002-01-01

296

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

Microsoft Academic Search

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

David A. Holwell; Iain McDonald

2006-01-01

297

Compounds of elements of Groups 11–13 containing (Me 3Si) 3C, (PhMe 2Si) 3C or related ligands  

Microsoft Academic Search

A survey is given of the preparation and properties of compounds of elements of Groups 11–13 containing the very bulky ligand (Me3Si)3C or (PhMe2Si)3C, or a related ligand of the type (Me3Si)2(XMe2Si)C.

Colin Eaborn; J. David Smith

1996-01-01

298

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

299

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

300

Nuclear localization of v-Abl leads to complex formation with cyclic AMP response element (CRE)-binding protein and transactivation through CRE motifs.  

PubMed Central

Deregulated expression of v-abl and BCR/abl genes has been associated with myeloproliferative syndromes and myelodysplasia, both of which can progress to acute leukemia. These studies identify the localization of the oncogenic form of the abl gene product encoded by the Abelson murine leukemia virus in the nuclei of myeloid cells and the association of the v-Abl protein with the transcriptional regulator cyclic AMP response element-binding protein (CREB). We have mapped the specific domains within each of the proteins responsible for this interaction. We have shown that complex formation is a prerequisite for transcriptional potentiation of CREB. Transient overexpression of the homologous cellular protein c-Abl also results in the activation of promoters containing an intact CRE. These observations identify a novel function for v-Abl, that of a transcriptional activator that physically interacts with a transcription factor.

Birchenall-Roberts, M C; Ruscetti, F W; Kasper, J J; Bertolette, D C; Yoo, Y D; Bang, O S; Roberts, M S; Turley, J M; Ferris, D K; Kim, S J

1995-01-01

301

Theoretical determination of steric characteristics of ligands. Cone angles of hydrides and halides of group-IV and group-V elements  

SciTech Connect

A formula for the calculation of the cone angle Theta of ligands of the type AB/sub n/ (A and B are atoms, and A is coordinated by the metal M) on the basis of the internuclear distance M-A, the covalent radii of A and B, the van der Waals radius of B, and the angle MAB has been proposed. The cone angles for ligands of the type AB/sub 3/, where A = N, P, As, Sb, Bi, C, Si, Ge, Sn, and Pb, and B = H, F, Cl, Br, and I, have been calculated. The laws governing the variation of the angles as a function of A and B have been established. In the case of a variable B, downward movement in the periodic table is accompanied by a significant increase in the cone angles, whereas in the case of a variable A, it is accompanied by some decrease in the cone angles. The cone angles of hydrides are only slightly dependent on A and range from 90 to 93/sup 0/. It has been shown that the cone angles for neighbors along periods are practically identical in the cases of N and C, P and Si, and As and Ge and are close in the cases of Sb and Sn and of Bi and Pb. The values of the cone angles for PH/sub 3/, PF/sub 3/, PCl/sub 3/, and PBr/sub 3/, which were previously obtained by measurements on molecular models, have been refined.

Imyanitov, N.S.

1986-06-01

302

Solid-state 207pb nmr studies of lead-group 16 and mixedtransition-metal-lead-group 16 element-containing materials  

SciTech Connect

207Pb solid-state NMR studies have been conducted on binarylead-group 16 and mixed transition-metal/lead group 16 materials,correlating the NMR chemical shifts of the materials with theirstructures. The experimental results show that the 207Pb chemical shiftsare strongly influenced by the local electronic structure. Data arereported for lead selenide, lead selenate, calcium plumbate, strontiumplumbite, barium plumbite, lead borate, lead zirconate, lead tungstate,lead meta-tantalate, lead niobate, lead molybdate, lead meta-vanadate,lead sulfite, and lead sulfate.

Van Bramer, S.E.; Glatfelter, A.; Bai, S.; Dybowksi, C.; GNeue,G.; Perry, D.L.

2005-08-26

303

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

NASA Astrophysics Data System (ADS)

The Xinjie mafic-ultramafic layered intrusion in the Emeishan large igneous province (ELIP) hosts Cu-Ni-platinum group element (PGE) sulfide ore layers within the lower part and Fe-Ti-V oxide-bearing horizons within the middle part. The major magmatic Cu-Ni-PGE sulfide ores and spatially associated cumulate rocks are examined for their PGE contents and Re-Os isotopic systematics. The samples yielded a Re-Os isochron with an age of 262 ± 27 Ma and an initial 187Os/ 188Os of 0.12460 ± 0.00011 ( ?Os( t) = -0.5 ± 0.1). The age is in good agreement with the previously reported U-Pb zircon age, indicating that the Re-Os system remained closed for most samples since the intrusion emplacement. They have near-chondritic ?Os( t) values ranging from -0.7 to -0.2, similar to those of the Lijiang picrites and Song Da komatiites. Exceptionally, two samples from the roof zone and one from upper sequence exhibit radiogenic ?Os( t) values (+0.6 to +8.6), showing minor contamination by the overlying Emeishan basalts. The PGE-rich ores contain relatively high PGE and small amounts of sulfides (generally less than 2%) and the abundance of Cu and PGE correlate well with S, implying that the distribution of these elements is controlled by the segregation and accumulation of a sulfide liquid. Some ore samples are poor in S (mostly <800 ppm), which may due to late-stage S loss caused by the dissolution of FeS from pre-existing sulfides through their interaction with sulfide-unsaturated flowing magma. The combined study shows that the Xinjie intrusion may be derived from ferropicritic magmas. The sharp reversals in Mg#, Cr/FeO T and Cr/TiO 2 ratios immediately below Units 2-4, together with high Cu/Zr ratios decreasing from each PGE ore layer within these cyclic units, are consistent with multiple magma replenishment episodes. The sulfides in the cumulate rocks show little evidence of PGE depletion with height and thus appear to have segregated from successive inputs of fertile magma. This suggests that the Xinjie intrusion crystallized from in an open magma system, e.g., a magma conduit. The compositions of the disseminated sulfides in most samples can be modeled by applying an R factor (silicate-sulfide mass ratio) of between 1000 and 8000, indicating the segregation of only small amounts of sulfide liquid in the parental ferropicritic magmas. Thus, continuous mixing between primitive ferropicritic magma and differentiated resident magma could lead to crystallization of chromite, Cr-bearing magnetite and subsequently abundant Fe-Ti oxides, thereby the segregation of PGE-rich Cu-sulfide. When considered in the light of previous studies on plume-derived komatiites and picrites worldwide, the close-to-chondritic Os isotopic composition for most Xinjie samples, Lijiang picrites and Song Da komatiites suggest that the ferropicritic magma in the ELIP were generated from a plume. This comprised recycled Neoproterozic oceanic lithosphere, including depleted peridotite mantle embedded with geochemically enriched domains. The ascending magmas thereafter interacted with minor (possibly <10%) subducted/altered oceanic crust. This comparison suggests that the komatiitic melts in the ELIP originated from a greater-than normal degree of melting of incompatible trace element depleted, refractory mantle components in the plume source.

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

2011-03-01

304

Effects of liquid immiscibility on trace element fractionation in magmatic iron meteorites: A case study of group IIIAB  

Microsoft Academic Search

Magmatic iron meteorites are generally agreed to represent metal that crystallized in asteroidal cores from a large pool of liquid. Estimates suggest that the metallic liquid contained significant amounts of S and P, both of which are incompatible and exert a strong effect on trace-element partitioning. In tandem, S and P are also prone to cause immiscibility between sulfide liquid

Finn Ulff-Moeller

1998-01-01

305

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  

Microsoft Academic Search

Concentrations of platinum group elements (PGE), Ag, As, Au, Bi, Cd, Co, Mo, Pb, Re, Sb, Se, Sn, Te, and Zn, have been determined\\u000a in base metal sulfide (BMS) minerals from the western branch (402 Trough orebodies) of the Creighton Ni–Cu–PGE sulfide deposit,\\u000a Sudbury, Canada. The sulfide assemblage is dominated by pyrrhotite, with minor pentlandite, chalcopyrite, and pyrite, and\\u000a they

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

2010-01-01

306

HEAVY ELEMENT DETERMINATIOiV IN HEALTH-RELATED ORGANIC MATRIX MATERIALS BY TOTAL REFLECTION X-RAY FLUORESCENCE  

Microsoft Academic Search

Recent developments in TXRF techniques make the method appropriate for simple, accurate and precise analysis of heavy elements in organic materials in health-related and pollution problems. Special advantages are derived by the use of monochromatized beams of X- rays: i) The reduction in the spectrum background allows direct irradiation of organic matter specimens. Hence human tissue and body fluids are

E. D. Greaves

307

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

Microsoft Academic Search

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

Erwin L Zodrow; Maria Mastalerz; William H Orem; Arden R Bashforth

2000-01-01

308

Technique for WWER-Type Reactor Fuel Element Cluster Power Calculation in the Two-Group Diffusion Approximation.  

National Technical Information Service (NTIS)

The technique for the two-group diffusion problem solution in the region consisting of rectilinear hexahedral prisms with different group cross sections is given. The technique is realized in the BIPR-6 programm, using the coarse pitch of the difference g...

A. A. Marakazov

1977-01-01

309

Laser ablation ICP-MS study of platinum-group elements in sulphides from the Platreef at Turfspruit, northern limb of the Bushveld Complex, South Africa  

Microsoft Academic Search

The Platreef unit of the northern Bushveld Complex comprises a diverse package of pyroxenites, peridotites and mafic lithologies\\u000a with associated Ni–Cu–platinum-group element (PGE) mineralisation. Base metal sulphides (BMS) are generally more abundant\\u000a in the Platreef than in other Bushveld PGE deposits, such as the Merensky Reef and the UG2 chromitite, but the Platreef, though\\u000a thicker, has lower overall PGE grades.

D. Hutchinson; I. McDonald

2008-01-01

310

Energy Spectra and Elemental Composition of Nuclei above 100 TeV from a Series of JACEE Balloon Flights  

Microsoft Academic Search

The Japanese-American Cooperative Emulsion Experiment (JACEE) has recently carried out a series of Antarctic circumpolar balloon flights (JACEE-10 ~ JACEE-13) for the study of high energy elemental composition and energy spectra of cosmic rays. The total exposure factor of these experiments is 663 m**2-hr, which is about twice the cumulative exposure from JACEE-1 through JACEE-8. Preliminary results from the Antarctic

T. H. Burnett; M. L. Cherry; K. Chevli; M. J. Christl; S. Dake; J. H. Derrickson; W. F. Fountain; M. Fuki; J. C. Gregory; T. Hayashi; R. Holynski; J. Iwai; A. Iyono; J. Johnson; W. V. Jones; M. Kobayashi; J. J. Lord; O. Miyamura; K. H. Moon; H. Oda; T. Ogata; E. D. Olson; T. A. Parnell; F. E. Roberts; K. Sengupta; T. Shiina; S. C. Strausz; T. Sugitate; Y. Takahashi; T. Tominaga; J. W. Watts; J. P. Wefel; B. Wilczynska; H. Wilczynski; R. J. Wilkes; W. Wolter; H. Yokomi; E. L. Zager

1995-01-01

311

Element- and size-dependent electron delocalization in AuNX+ clusters (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni).  

PubMed

We investigated the stability of gold clusters doped with open 3d-shell atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni). Steps, peaks, and odd-even staggering in mass abundance spectra upon photofragmentation provide evidence for enhanced stability for specific cluster sizes. The observed magic numbers are explained in terms of size- and dopant-dependent modifications of the effective mean-field potential within a phenomenological shell-model approach. Element-dependent 3d electron delocalization and odd-even staggering amplitudes are related to the dopant-atom structure. PMID:12570488

Neukermans, S; Janssens, E; Tanaka, H; Silverans, R E; Lievens, P

2003-01-24

312

First measurement of the ratio B(t --> Wb)/B(t --> Wq) and associated limit on the Cabibbo-Kobayashi-Maskawa element /V(tb)/.  

PubMed

We present the first measurement of the ratio of branching fractions R identical withB(t-->Wb)/B(t-->Wq) from p_p collisions at sqrt[s] = 1.8 TeV. The data set corresponds to 109 pb(-1) of data recorded by the Collider Detector at Fermilab during the 1992-95 Tevatron run. We measure R = 0.94(+0.31)(-0.24)(stat+syst) or R>0.61 (0.56) at 90% (95)% C.L., in agreement with the standard model predictions. This measurement yields a limit on the Cabibbo-Kobayashi-Maskawa quark mixing matrix element /V(tb)/ under the assumption of three generations and unitarity. PMID:11327939

Affolder, T; Akimoto, H; Akopian, A; Albrow, M G; Amaral, P; Amendolia, S R; Amidei, D; Anikeev, K; Antos, J; Apollinari, G; Arisawa, T; Asakawa, T; Ashmanskas, W; Azfar, F; Azzi-Bacchetta, P; Bacchetta, N; Bailey, M W; Bailey, S; de Barbaro, P; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Barone, M; Bauer, G; Bedeschi, F; Belforte, S; Bell, W H; Bellettini, G; Bellinger, J; Benjamin, D; Bensinger, J; Beretvas, A; Berge, J P; Berryhill, J; Bevensee, B; Bhatti, A; Binkley, M; Bisello, D; Bishai, M; Blair, R E; Blocker, C; Bloom, K; Blumenfeld, B; Blusk, S R; Bocci, A; Bodek, A; Bokhari, W; Bolla, G; Bonushkin, Y; Bortoletto, D; Boudreau, J; Brandl, A; van den Brink, S; Bromberg, C; Brozovic, M; Bruner, N; Buckley-Geer, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Byon-Wagner, A; Byrum, K L; Calafiura, P; Campbell, M; Carithers, W; Carlson, J; Carlsmith, D; Caskey, W; Cassada, J; Castro, A; Cauz, D; Cerri, A; Chan, A W; Chang, P S; Chang, P T; Chapman, J; Chen, C; Chen, Y C; Cheng, M T; Chertok, M; Chiarelli, G; Chirikov-Zorin, I; Chlachidze, G; Chlebana, F; Christofek, L; Chu, M L; Chung, Y S; Ciobanu, C I; Clark, A G; Connolly, A; Conway, J; Cordelli, M; Cranshaw, J; Cronin-Hennessy, D; Cropp, R; Culbertson, R; Dagenhart, D; D'Auria, S; DeJongh, F; Dell'Agnello, S; Dell'Orso, M; Demortier, L; Deninno, M; Derwent, P F; Devlin, T; Dittmann, J R; Donati, S; Done, J; Dorigo, T; Eddy, N; Einsweiler, K; Elias, J E; Engels, E; Erbacher, R; Errede, D; Errede, S; Fan, Q; Feild, R G; Fernandez, J P; Ferretti, C; Field, R D; Fiori, I; Flaugher, B; Foster, G W; Franklin, M; Freeman, J; Friedman, J; Fukui, Y; Furic, I; Galeotti, S; Gallinaro, M; Gao, T; Garcia-Sciveres, M; Garfinkel, A F; Gatti, P; Gay, C; Gerdes, D W; Giannetti, P; Giromini, P; Glagolev, V; Glenzinski, D; Gold, M; Goldstein, J; Gordon, A; Gorelov, I; Goshaw, A T; Gotra, Y; Goulianos, K; Green, C; Grim, G; Gris, P; Groer, L; Grosso-Pilcher, C; Guenther, M; Guillian, G; Da Costa, J G; Haas, R M; Haber, C; Hafen, E; Hahn, S R; Hall, C; Handa, T; Handler, R; Hao, W; Happacher, F; Hara, K; Hardman, A D; Harris, R M; Hartmann, F; Hatakeyama, K; Hauser, J; Heinrich, J; Heiss, A; Herndon, M; Hill, C; Hoffman, K D; Holck, C; Hollebeek, R; Holloway, L; Hughes, R; Huston, J; Huth, J; Ikeda, H; Incandela, J; Introzzi, G; Iwai, J; Iwata, Y; James, E; Jensen, H; Jones, M; Joshi, U; Kambara, H; Kamon, T; Kaneko, T; Karr, K; Kasha, H; Kato, Y; Keaffaber, T A; Kelley, K; Kelly, M; Kennedy, R D; Kephart, R; Khazins, D; Kikuchi, T; Kilminster, B; Kim, B J; Kim, D H; Kim, H S; Kim, M J; Kim, S H; Kim, Y K; Kirby, M; Kirk, M; Kirsch, L; Klimenko, S; Koehn, P; Köngeter, A; Kondo, K; Konigsberg, J; Kordas, K; Korn, A; Korytov, A; Kovacs, E; Kroll, J; Kruse, M; Kuhlmann, S E; Kurino, K; Kuwabara, T; Laasanen, A T; Lai, N; Lami, S; Lammel, S; Lamoureux, J I; Lancaster, J; Lancaster, M; Lander, R; Latino, G; LeCompte, T; Lee, A M; Lee, K; Leone, S; Lewis, J D; Lindgren, M; Liss, T M; Liu, J B; Liu, Y C; Litvintsev, D O; Lobban, O; Lockyer, N; Loken, J; Loreti, M; Lucchesi, D; Lukens, P; Lusin, S; Lyons, L; Lys, J; Madrak, R; Maeshima, K; Maksimovic, P; Malferrari, L; Mangano, M; Mariotti, M; Martignon, G; Martin, A; Matthews, J A; Mayer, J; Mazzanti, P; McFarland, K S; McIntyre, P; McKigney, E; Menguzzato, M; Menzione, A; Mesropian, C; Meyer, A; Miao, T; Miller, R; Miller, J S; Minato, H; Miscetti, S; Mishina, M; Mitselmakher, G; Moggi, N; Moore, E; Moore, R; Morita, Y; Moulik, T; Mulhearn, M; Mukherjee, A; Muller, T; Munar, A; Murat, P; Murgia, S; Nachtman, J; Nagaslaev, V; Nahn, S; Nakada, H; Nakaya, T; Nakano, I; Nelson, C; Nelson, T; Neu, C; Neuberger, D; Newman-Holmes, C; Ngan, C Y; Niu, H; Nodulman, L; Nomerotski, A; Oh, S H; Ohmoto, T; Ohsugi, T; Oishi, R; Okusawa, T; Olsen, J; Orejudos, W; Pagliarone, C; Palmonari, F; Paoletti, R; Papadimitriou, V; Pappas, S P; Partos, D; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pescara, L; Phillips, T J; Piacentino, G; Pitts, K T; Pompos, A; Pondrom, L; Pope, G; Popovic, M; Prokoshin, F; Proudfoot, J; Ptohos, F; Pukhov, O; Punzi, G; Ragan, K; Rakitine, A; Reher, D; Reichold, A; Ribon, A; Riegler, W; Rimondi, F; Ristori, L; Riveline, M; Robertson, W J; Robinson, A; Rodrigo, T; Rolli, S; Rosenson, L; Roser, R; Rossin, R; Roy, A; Safonov, A; St Denis, R; Sakumoto, W K; Saltzberg, D; Sanchez, C; Sansoni, A; Santi, L; Sato, H; Savard, P; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Scodellaro, L; Scott, A; Scribano, A; Segler, S; Seidel, S; Seiya, Y; Semenov, A; Semeria, F; Shah, T; Shapiro, M D; Shepard, P F; Shibayama, T; Shimojima, M; Shochet, M; Siegrist, J; Sill, A; Sinervo, P; Singh, P; Slaughter, A J; Sliwa, K; Smith, C; Snider, F D; Solodsky, A; Spalding, J; Speer, T; Sphicas, P; Spinella, F; Spiropulu, M; Spiegel, L; Steele, J; Stefanini, A; Strologas, J; Strumia, F; Stuart, D; Sumorok, K; Suzuki, T

2001-04-01

313

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

Microsoft Academic Search

The major element relationships in ferromanganese (Fe-Mn) crusts from Afanasiy-Nikitin seamount (ANS), eastern equatorial\\u000a 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\\u000a ANS Fe-Mn crusts are distinct from Pacific seamount Fe-Mn crusts, and reflect region-specific chemical

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

2007-01-01

314

Human group V secretory phospholipase A2 is associated with lipid rafts and internalized in a flotillin?dependent pathway.  

PubMed

The mechanisms of secretory phospholipase A2 (sPLA2) action are not understood clearly. Previously, it was suggested that sPLA2s are internalized into cells for the targeting of sPLA2 to intracellular action sites. However, the mechanisms for sPLA2 internalization remain to be identified. The present study demonstrated for the first time that human group V sPLA2 (hVPLA2) is associated with lipid rafts and is internalized in a flotillin?dependent pathway. The lipid raft association was probed by cholesterol?sensitive enrichment of hVPLA2 in low?density fractions and co?patching of ganglioside GM1 rafts through cross?linking of hVPLA2 in HEK293 and CHO cells. The hVPLA2 associated with lipid rafts was shown to be internalized into HEK293 cells at a relatively rapid rate (t1/2 =16 min) and this internalization was inhibited by the knockdown of flotillin?1, but not by chlorpromazine, an inhibitor of clathrin?mediated endocytosis. Moreover, internalized hVPLA2 was shown to be colocalized extensively with flotillin?1 in a punctate structure, but not caveolin?1. These data revealed that the internalization of hVPLA2 is mediated by flotillin?1. Attenuation of arachidonic acid release from plasma membrane through the association of hVPLA2 with lipid rafts suggested that this association with lipid rafts may be important in protecting mammalian cells from excessive degradation of plasma membrane and trafficking hVPLA2 into intracellular targets. PMID:24042857

Rhee, Hae Jin; Ji, Liting; Kim, Seung-Hyuk; Lee, Jongho

2013-09-12

315

Secretory group V phospholipase A2 regulates acute lung injury and neutrophilic inflammation caused by LPS in mice  

PubMed Central

We investigated the regulatory role of 14-kDa secretory group V phospholipase A2 (gVPLA2) in the development of acute lung injury (ALI) and neutrophilic inflammation (NI) caused by intratracheal administration of LPS. Experiments were conducted in gVPLA2 knockout (pla2g5?/?) mice, which lack the gene, and gVPLA2 wild-type littermate control (pla2g5+/+) mice. Indices of pulmonary injury were evaluated 24 h after intratracheal administration of LPS. Expression of gVPLA2 in microsections of airways and mRNA content in lung homogenates were increased substantially in pla2g5+/+ mice after LPS-administered compared with saline-treated pla2g5+/+ mice. By contrast, expression of gVPLA2 was neither localized in LPS- nor saline-treated pla2g5?/? mice. LPS also caused 1) reduced transthoracic static compliance, 2) lung edema, 3) neutrophilic infiltration, and 4) increased neutrophil myeloperoxidase activity in pla2g5+/+ mice. These events were attenuated in pla2g5?/? mice exposed to LPS or in pla2g5+/+ mice receiving MCL-3G1, a neutralizing MAb directed against gVPLA2, before LPS administration. Our data demonstrate that gVPLA2 is an inducible protein in pla2g5+/+ mice but not in pla2g5?/? mice within 24 h after LPS treatment. Specific inhibition of gVPLA2 with MCL-3G1 or gene-targeted mice lacking gVPLA2 blocks ALI and attenuates NI caused by LPS.

Munoz, Nilda M.; Meliton, Angelo Y.; Meliton, Lucille N.; Dudek, Steven M.; Leff, Alan R.

2009-01-01

316

Analytical microscopy observations of rat enterocytes after oral administration of soluble salts of lanthanides, actinides and elements of group III-A of the periodic chart.  

PubMed

The behavior in the intestinal barrier of nine elements (three of the group III-A, four lanthanides and two actinides), absorbed as soluble salts, has been studied by two microanalytical methods: electron probe X-ray micro analysis (EPMA) and secondary ion mass spectrometry (SIMS). It has been shown that the three elements of group III-A, aluminium, gallium and indium; and the four lanthanides, lanthanum, cerium, europium and thulium, are selectively concentrated and precipitated as non-soluble form in enterocytes of proximal part of the intestinal tract. SIMS microscopy has shown that these elements are concentrated as a number of submicroscopic precipitates, most of them localized in the apical part of the duodenum enterocytes, where they are observed from one hour to 48 hr after a single intragastric administration. No precipitate is observed after three days. It is suggested that this mechanism of local concentration limits the diffusion of these elements through the digestive barrier, some of them being toxic and none of them having a recognized physiological role. Additionally, the precipitation in duodenal enterocytes, the life time of which is on the order of 2-3 days, allows the elements absorbed as soluble form to be eliminated as a non-soluble form in the digestive lumen along with the desquamation of the apoptotic enterocytes. The intracytoplasmic localization of the precipitates are supposed to be the lysosomes although no direct evidence could be given here due to the very small sizes of the lysosomes of enterocytes. The same results were not observed with the two studied actinides. After administration of thorium, only some very sparse microprecipitates could be observed in intestinal mucosa and, after administration of uranium, no precipitates were observed with the exception of some in the conjunctive part of the duodenal villi. PMID:11441948

Floren, C; Tekaya, L; Escaig, F; Labejof, L; Mouthon, G; Galle, P

2001-05-01

317

Key Role of Group V Secreted Phospholipase A2 in Th2 Cytokine and Dendritic Cell-Driven Airway Hyperresponsiveness and Remodeling  

PubMed Central

Background Previous work has shown that disruption of the gene for group X secreted phospholipase A2 (sPLA2-X) markedly diminishes airway hyperresponsiveness and remodeling in a mouse asthma model. With the large number of additional sPLA2s in the mammalian genome, the involvement of other sPLA2s in the asthma model is possible – in particular, the group V sPLA2 (sPLA2-V) that like sPLA2-X is highly active at hydrolyzing membranes of mammalian cells. Methodology and Principal Findings The allergen-driven asthma phenotype was significantly reduced in sPLA2-V-deficient mice but to a lesser extent than observed previously in sPLA2-X-deficient mice. The most striking difference observed between the sPLA2-V and sPLA2-X knockouts was the significant impairment of the primary immune response to the allergen ovalbumin (OVA) in the sPLA2-V?/? mice. The impairment in eicosanoid generation and dendritic cell activation in sPLA2-V?/? mice diminishes Th2 cytokine responses in the airways. Conclusions This paper illustrates the diverse roles of sPLA2s in the immunopathogenesis of the asthma phenotype and directs attention to developing specific inhibitors of sPLA2-V as a potential new therapy to treat asthma and other allergic disorders.

Henderson Jr, William R.; Ye, Xin; Lai, Ying; Ni, Zhanglin; Bollinger, James G.; Tien, Ying-Tzang; Chi, Emil Y.; Gelb, Michael H.

2013-01-01

318

Molecular Analysis of V, and V, Regions Expressed in IgG-Bearing Chronic Lymphocytic Leukemia (CLL): Further Evidence That CLL Is a Heterogeneous Group of Tumors  

Microsoft Academic Search

We report the heavy (H) and light (L) chain variable (V) re- gion sequences of cDNAs encoding the lg receptor of two cases of CD5 + IgG-bearing CLL P87 and P103. In both CLL cases the H chain was encoded by members of the VH3 gene family. The L chain expressed by P87 belonged to the VJV subgroup, whereas P103

Saskia B. Ebeling; Mieke E. M. Schutte; Ton Logtenberg

1993-01-01

319

M-shell X-ray production cross-sections for elements with 67 {<=} Z {<=} 92 at incident photon energies E{sub M{sub 1}}V  

SciTech Connect

The X-ray production cross-sections for the Mk (k = {xi}, {delta}, {alpha}, {beta}, {zeta}, {gamma}, m{sub 1} and m{sub 2}) groups of X-rays have been evaluated for all the elements with 67 {<=} Z {<=} 92 at incident photon energies ranging E{sub M{sub 1}}V using currently available theoretical data sets of different physical parameters, namely, partial photoionization cross-sections, X-ray emission rates, fluorescence and Coster-Kronig yields, and the K-shell/L{sub j} (j = 1-3) subshell to the M{sub i} (i = 1-5) subshell vacancy transfer probabilities, based on the independent particle models.

Chauhan, Yogeshwar; Kumar, Anil [University College of Engineering, Punjabi University, Patiala 147002, Punjab (India); Puri, Sanjiv [University College of Engineering, Punjabi University, Patiala 147002, Punjab (India)], E-mail: sanjivpurichd@yahoo.com

2009-07-15

320

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.

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

2002-01-01

321

Synthesis and properties of sulphonated phthalocyanines of IV group elements as possible new dyes for PDT of cancer  

NASA Astrophysics Data System (ADS)

The introduction of sulpho groups into molecule of mono- and diphthalocyanines of hafnium and zirconium gave rise to the formation of water soluble compounds. This allows us to extend the field of their applications. The dyes of this class have been found to be efficient photosensitizers for PDT of cancer.

Ovchinnikova, N. A.; Tomilova, Larisa G.; Podgaetsky, V. M.

1994-03-01

322

The scattering characteristics of stimulated Raman scattering (SRS) mirrors based on tetrachloride elements in Group IV of the periodic table  

Microsoft Academic Search

The characteristics of stimulated Raman scattering (SRS) mirrors built from SiC4, TiCl4, SbCl4, and CCl4 have been investigated, experimentally. The use of tetrachlorides from Group IV in the periodic table as nonlinear wavefront reversal media is demonstrated. The scattering characteristics of the tetrachloride metals are discussed in detail.

V. M. Volynkin; K. V. Gratsianov; A. N. Kolesnikov; Iu. I. Kruzhilin; V. V. Liubimov

1985-01-01

323

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…

Hom, Willard

324

Surface organometallic chemistry of main group elements: selective synthesis of silica supported [triple bond Si-OB(C(6)F(5))(3)](-)[HNEt(2)Ph](+).  

PubMed

The reaction of the Lewis acid B(C(6)F(5))(3) with silanol groups of silica surfaces, dehydroxylated at different temperatures (300, 500, 700, and 800 degrees C), has been investigated in presence of the Brønsted base NEt(2)Ph. The structure of the resulting modified silica supports [triple bond Si-OB(C(6)F(5))(3)](-)[HNEt(2)Ph](+) (1) has been carefully identified by IR and multinuclear solid-state NMR spectroscopies, isotopic (2)H and (18)O labeling, elemental analysis, molecular modeling, and comparison with synthesized molecular models. Highly dehydroxylated silica surfaces were required to transform selectively each silanol group into unique [triple bond Si-OB(C(6)F(5))(3)](-)[HNEt(2)Ph](+) fragments. For lower dehydroxylation temperatures, two sorts of surface sites were coexisting on silica: the free silanol groups [triple bond SiOH] and the ionic species 1. PMID:11921228

Millot, Nicolas; Cox, Andrew; Santini, Catherine C; Molard, Yann; Basset, Jean-Marie

2002-03-15

325

On the interactions of point defects, dopants and light element impurities in silicon as stimulated by 200 kV electron irradiation  

NASA Astrophysics Data System (ADS)

The purpose of this research has been the investigation of atomic manipulation in silicon. It has been demonstrated that bulk vacancies and interstitials are created and spatially separated one Frenkel pair at a time during 200 kV electron irradiation of nitrogen-doped silicon. The mechanism by which the nitrogen pair allows Frenkel pair separation is shown to be a combination of the lowering of the energy barrier to a knock-on event combined with a more stable end-state. Anomalous nitrogen diffusion has been observed as a result of low energy ion milling, and the diffusion of nitrogen is studied theoretically, revealing a new, low energy model for N2 pair diffusion. For the first time, 200 kV irradiation has been demonstrated not only to create Frenkel pairs during broad-beam irradiation, but also to allow the formation of extended defects like voids, oxygen precipitates and interstitial complexes. Using electron energy loss spectroscopy combined with first principles simulations, dark and bright areas induced in Z contrast images by 200 kV irradiation are demonstrated to be due to vacancy and self-interstitial complexes, respectively, with N > 2. Finally, the manipulation of dopants in silicon is induced by using the difference in energy transferable from a 200 kV electron to light versus heavy elements (e.g. B vs. Sb). Atomic Force Microscopy is used to demonstrate that n-type regions with a size corresponding to the beam diameter are created in p-type material by short periods of 200 kV e-beam exposure. In this way, a method can be developed to create p-n-p type devices of arbitrary size in codoped silicon using a room temperature process.

Stoddard, Nathan Gregory

326

Noncoding transcription within the Igh distal V(H) region at PAIR elements affects the 3D structure of the Igh locus in pro-B cells.  

PubMed

Noncoding sense and antisense germ-line transcription within the Ig heavy chain locus precedes V(D)J recombination and has been proposed to be associated with Igh locus accessibility, although its precise role remains elusive. However, no global analysis of germ-line transcription throughout the Igh locus has been done. Therefore, we performed directional RNA-seq, demonstrating the locations and extent of both sense and antisense transcription throughout the Igh locus. Surprisingly, the majority of antisense transcripts are localized around two Pax5-activated intergenic repeat (PAIR) elements in the distal IghV region. Importantly, long-distance loops measured by chromosome conformation capture (3C) are observed between these two active PAIR promoters and E?, the start site of I? germ-line transcription, in a lineage- and stage-specific manner, even though this antisense transcription is E?-independent. YY1(-/-) pro-B cells are greatly impaired in distal V(H) gene rearrangement and Igh locus compaction, and we demonstrate that YY1 deficiency greatly reduces antisense transcription and PAIR-E? interactions. ChIP-seq shows high level YY1 binding only at E?, but low levels near some antisense promoters. PAIR-E? interactions are not disrupted by DRB, which blocks transcription elongation without disrupting transcription factories once they are established, but the looping is reduced after heat-shock treatment, which disrupts transcription factories. We propose that transcription-mediated interactions, most likely at transcription factories, initially compact the Igh locus, bringing distal V(H) genes close to the DJ(H) rearrangement which is adjacent to E?. Therefore, we hypothesize that one key role of noncoding germ-line transcription is to facilitate locus compaction, allowing distal V(H) genes to undergo efficient rearrangement. PMID:23027941

Verma-Gaur, Jiyoti; Torkamani, Ali; Schaffer, Lana; Head, Steven R; Schork, Nicholas J; Feeney, Ann J

2012-10-01

327

A General Approach for Sharp Crystal Phase Switching in InAs, GaAs, InP, and GaP Nanowires Using Only Group V Flow.  

PubMed

III-V-based nanowires usually exhibit random mixtures of wurtzite (WZ) and zinc blende (ZB) crystal structure, and pure crystal phase wires represent the exception rather than the rule. In this work, the effective group V hydride flow was the only growth parameter which was changed during MOVPE growth to promote transitions from WZ to ZB and from ZB to WZ. Our technique works in the same way for all investigated III-Vs (GaP, GaAs, InP, and InAs), with low group V flow for WZ and high group V flow for ZB conditions. This strongly suggests a common underlying mechanism. It displays to our best knowledge the simplest changes of the growth condition to control the nanowire crystal structure. The inherent reduction of growth variables is a crucial requirement for the interpretation in the frame of existing understanding of polytypism in III-V nanowires. We show that the change in surface energetics of the vapor-liquid-solid system at the vapor-liquid and liquid-solid interface is likely to control the crystal structure in our nanowires. PMID:23902379

Lehmann, Sebastian; Wallentin, Jesper; Jacobsson, Daniel; Deppert, Knut; Dick, Kimberly A

2013-08-07

328

Platinum-group element mineralogy and geochemistry of chromitite of the Kluchevskoy ophiolite complex, central Urals (Russia)  

Microsoft Academic Search

We report the results of investigation of chromitites occurring in the Kluchevskoy ophiolite complex of the Russian Urals. The chromite composition suggests crystallization from a boninitic magma in a supra-subduction zone geodynamic setting. The investigated chromitites are enriched in Os–Ir–Ru over Rh–Pt–Pd, as typical of the mantle hosted ophiolite chromitites. Consistent with the geochemical data, the Platinum Group Mineral (PGM)

F. Zaccarini; E. Pushkarev; G. Garuti

2008-01-01

329

Electrophilic reactions of group-VI element halides. VIII. Reactions of selenium and tellurium tetrahalides with allyl cinnamate  

SciTech Connect

It was shown that, as a result of two-phase selenohalogenation or tellurohalogenation of allyl cinnamate at /minus/30 C, addition took place at the C/doteq/C bond of the allyl group; the C=C bond of the cinnamoyl moiety remained uninvolved. Selenium tetrahalides were added to allyl cinnamate in accordance with the Markownikoff rule, forming adducts with 1:2 composition; tellurium tetrahalides formed products of rearrangement of the adducts with a 1:1 composition.

Lendel, V.G.; Sani, A.Yu.; Balog, I.M.; Migalina, Yu.V.; Kornilov, M.Yu.; Turov, A.V.

1988-02-20

330

Role of group V phospholipase A2 in zymosan-induced eicosanoid generation and vascular permeability revealed by targeted gene disruption.  

PubMed

Conclusions regarding the contribution of low molecular weight secretory phospholipase A2 (sPLA2) enzymes in eicosanoid generation have relied on data obtained from transfected cells or the use of inhibitors that fail to discriminate between individual members of the large family of mammalian sPLA2 enzymes. To elucidate the role of group V sPLA2, we used targeted gene disruption to generate mice lacking this enzyme. Zymosan-induced generation of leukotriene C4 and prostaglandin E2 was attenuated approximately 50% in peritoneal macrophages from group V sPLA2-null mice compared with macrophages from wild-type littermates. Furthermore, the early phase of plasma exudation in response to intraperitoneal injection of zymosan and the accompanying in vivo generation of cysteinyl leukotrienes were markedly attenuated in group V sPLA2-null mice compared with wild-type controls. These data provide clear evidence of a role for group V sPLA2 in regulating eicosanoid generation in response to an acute innate stimulus of the immune response both in vitro and in vivo, suggesting a role for this enzyme in innate immunity. PMID:14761945

Satake, Yoshiyuki; Diaz, Bruno L; Balestrieri, Barbara; Lam, Bing K; Kanaoka, Yoshihide; Grusby, Michael J; Arm, Jonathan P

2004-02-04

331

Performance of the Vitek MS v2.0 system in distinguishing Streptococcus pneumoniae from nonpneumococcal species of the Streptococcus mitis group.  

PubMed

The Vitek MS v2.0 matrix-assisted laser desorption ionization-time of flight mass spectrometry system accurately distinguished Streptococcus pneumoniae from nonpneumococcal S. mitis group species. Only 1 of 116 nonpneumococcal isolates (<1%) was misidentified as S. pneumoniae. None of 95 pneumococcal isolates was misidentified. This method provides a rapid, simple means of discriminating among these challenging organisms. PMID:23784130

Branda, John A; Markham, Rachelle P; Garner, Cherilyn D; Rychert, Jenna A; Ferraro, Mary Jane

2013-06-19

332

Variations in the sensory threshold for faradic stimulation in psychopathic subjects: V. The group of the psychneuroses  

Microsoft Academic Search

Studied variations in the sensory threshold for faradism in a psychoneurotic group. The Martin Method (1913) was used. 30 cases, of which 18 were males and 12 were females, were grouped as suffering from: (1) occupation neurosis, (2) traumatic neurosis, (3) hysteria, (4) neurasthenia, and (5) psychoneurosis. The psychoneurotic group of cases, showed a normal aesthesia to faradism. Apart from

G. P. Grabfield

1916-01-01

333

3D finite element simulation of microstructure evolution in blade forging of Ti-6Al-4V alloy based on the internal state variable models  

NASA Astrophysics Data System (ADS)

The physically-based internal state variable (ISV) models were used to describe the changes of dislocation density, grain size, and flow stress in the high temperature deformation of titanium alloys in this study. The constants of the present models could be identified based on experimental results, which were conducted at deformation temperatures ranging from 1093 K to 1303 K, height reductions ranging from 20% to 60%, and the strain rates of 0.001, 0.01, 0.1, 1.0, and 10.0 s-1. The physically-based internal state variable models were implemented into the commercial finite element (FE) code. Then, a three-dimensional (3D) FE simulation system coupling of deformation, heat transfer, and microstructure evolution was developed for the blade forging of Ti-6Al-4V alloy. FE analysis was carried out to simulate the microstructure evolution in the blade forging of Ti-6Al-4V alloy. Finally, the blade forging tests of Ti-6Al-4V alloy were performed to validate the results of FE simulation. According to the tensile tests, it is seen that the mechanical properties, such as tensile strength and elongation, satisfy the application requirements well. The maximum and minimum differences between the calculated and experimental grain size of primary ? phase are 11.71% and 4.23%, respectively. Thus, the industrial trials show a good agreement with FE simulation of blade forging.

Luo, Jiao; Wu, Bin; Li, Miao-Quan

2012-02-01

334

Measuring the magnitude of the fourth-generation CKM{sub 4} matrix element V{sub t}{sup '}{sub b}{sup '} at the LHC  

SciTech Connect

We study the decays of heavy chiral (t{sup '},b{sup '}) quarks in a four-generation extension of the standard model. If the difference between the t{sup '} and b{sup '} masses is smaller than the W{sup {+-}} mass, as favored by precision electroweak measurements, then the Cabibbo-Kobayashi-Maskawa favored, on-shell decay t{sup '}{yields}b{sup '}W{sup +} is forbidden. As a result, other t{sup '} decays have substantial branching fractions, which are highly sensitive to the magnitude of the diagonal CKM matrix element V{sub t}{sup '}{sub b}{sup '}. We show that |V{sub t}{sup '}{sub b}{sup '}| can be determined from the ratio of the two-body and three-body t{sup '}-decay branching fractions and estimate the precision of such a measurement at the LHC. We discuss the hadronization of a t{sup '} for large enough values of |V{sub t}{sup '}{sub b}{sup '}|.

Das, Diganta; Sinha, Rahul [Institute of Mathematical Sciences, Taramani, Chennai 600113 (India); London, David [Physique des Particules, Universite de Montreal, C.P. 6128, succursale centre-ville, Montreal, Quebec, H3C 3J7 (Canada); Soffer, Abner [Tel Aviv University, Tel Aviv, 69978 (Israel)

2010-11-01

335

Modulation of the Activity of a Polycomb-Group Response Element in Drosophila by a Mutation in the Transcriptional Activator Woc  

PubMed Central

Polycomb group response elements (PRE) are cis-regulatory elements that bind Polycomb group proteins. We are studying a 181-bp PRE from the Drosophila engrailed gene. This PRE causes pairing-sensitive silencing of mini-white in transgenes. Here we show that the 181-bp PRE also represses mini-white expression in flies with only one copy of the transgene. To isolate mutations that alter the activity of the 181-bp PRE, we screened for dominant suppressors of PRE-mediated mini-white repression. Dominant suppressors of mini-white repression were rare; we recovered only nine mutations out of 68,274 progeny screened. Two of the nine mutations isolated are due to the same single amino acid change in the transcriptional activator Woc (without children). Reversion experiments show that these are dominant gain-of-function mutations in woc. We suggest that Woc can interfere with the activity of the PRE. Our data have implications for how Polycomb group proteins act to either partially repress or completely silence their target genes.

Noyes, Amanda; Stefaniuk, Catherine; Cheng, Yuzhong; Kennison, James A.; Kassis, Judith A.

2011-01-01

336

Formation and geochemical significance of micrometallic aggregates including fissiogenic platinum group elements in the Oklo natural reactor, Gabon  

NASA Astrophysics Data System (ADS)

Metallic aggregates with a size of a few tens ?m and consisting mainly of Ru, Rh, Pd, Te, Pb, As, Sb, S and Bi were found in the acid residue of SD37-S2/CD uraninite taken from Oklo natural reactor zone (RZ) 13. Quantitative analyses of major elements using an electron probe microanalyzer and in situ isotopic analyses of Zr, Mo, Ru, Pb and U using a sensitive high-resolution ion microprobe were performed on the metallic aggregates to determine the geochemical behaviors of fission products and actinides and to ascertain the processes of formation of the aggregates in the RZs. The chemical compositions of the aggregates investigated in this study are significantly different from those reported previously, showing lower Pb content and no correlation between the contents of Pb and S in the individual grains. The 235U/ 238U ratios in metallic aggregates vary significantly from 0.00478 to 0.01466, indicating chemical fractionation between U and Pu during the formation of the aggregates. The Pb isotopic data indicate that most of the Pb in the aggregates decayed from 2.05 Ga-old uraninite that existed in the RZ originally and that there was chemical fractionation between U and Pb in some aggregates. The Zr and Mo isotopic ratios, 90Zr/ 91Zr and 95Mo/ 97Mo, for most of the aggregates had small variations, which can be simply explained by constant separate mixing of fissiogenic and nonfissiogenic components. On the other hand, a large variation in the 99Ru/ 101Ru ratio (0.324-1.73) cannot be explained only by a two component mixing theory; thus, chemical fractionation between Tc and Ru during the reactor criticality is suggested. The large variations in the 235U/ 238U and 99Ru/ 101Ru isotopic ratios suggest that the aggregates formed under various redox conditions owing to the radiolysis of water.

Kikuchi, Makiko; Hidaka, Hiroshi; Gauthier-Lafaye, François

2010-08-01

337

Functionalization of cyclo-olefin polymer substrates by plasma oxidation: stable film containing carboxylic acid groups for capturing biorecognition elements.  

PubMed

Many current designs in biomedical diagnostics devices are based on the use of low cost, disposable, easy-to-fabricate chips made of plastic material, typically a cyclo-olefin polymer (COP). Low autofluorescence properties of such material, among others, make it ideal substrate for fluorescence-based applications. Functionalization of this plastic substrate for biomolecule attachment is therefore of great importance and the quality of films produced on such surface have often a significant influence on the performance of the device. In this communication we discuss the surface chemistry and some other characteristics of hydrophilic films, containing carboxylic acid functional groups, formed by plasma oxidation of COP and also films containing cross-linked, polymerized acryclic acid produced by sequential deposition of tetraorthosilicate and acrylic acid by plasma enhanced chemical vapor deposition (PECVD). Immobilization of labeled, single stranded DNA revealed high binding capacity for both coatings. To our best knowledge, this is the first example of direct immobilization of biomolecules on just plasma oxidized COP. Furthermore, more sophisticated treatment of the oxidized plastic substrate by PECVD with other organic precursors increased the binding capacity by some 40% than that of just plasma oxidized COP. The carboxy functionalized surfaces, due to the negative charge of the carboxy groups, showed very positive trends towards increasing the signal to noise ratio when charged biomolecules such as DNA, are used. PMID:20728322

Gubala, Vladimir; Le, Nam Cao Hoai; Gandhiraman, Ram Prasad; Coyle, Conor; Daniels, Stephen; Williams, David E

2010-08-03

338

Fragmentation cross sections of 290 and 400 MeV/nucleon C12 beams on elemental targets  

NASA Astrophysics Data System (ADS)

Charge-changing and fragment production cross sections at 0° have been obtained for interactions of 290 and 400 MeV/nucleon carbon beams with C, CH2, Al, Cu, Sn, and Pb targets. These beams are relevant to cancer therapy, space radiation, and the production of radioactive beams. We compare these results against previously published results using C and CH2 targets at similar beam energies. Because of ambiguities arising from the presence of multiple fragments on many events, the previous publications reported only cross sections for B and Be fragments. In this work, we have extracted cross sections for all fragment species, using data obtained at three distinct values of angular acceptance, supplemented by data taken with the detector stack placed off the beam axis. A simulation of the experiment with the particle and heavy ion transport system (PHITS) Monte Carlo model shows fair agreement with the data obtained with the large-acceptance detectors, but agreement is poor at small acceptance. The measured cross sections are also compared with the predictions of the one-dimensional cross section models EPAX2 and NUCFRG2; the latter is presently used in NASA's space radiation transport calculations. Though PHITS and NUCFRG2 reproduce the charge-changing cross sections with reasonable accuracy, none of the models is able to accurately predict the fragment cross sections for all fragment species and target materials.

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

2007-07-01

339

Towards efficient p-type doping of ZnO with group-V atoms: N versus As and Sb  

Microsoft Academic Search

ZnO films were fabricated by oxidation of thin layers of Zn-V compounds and of ZnTe. Controlled p-type doping with N, As, and Sb was obtained. The most efficient doping is observed for ZnO:As in the presence of isoelectronic Te ions. Stable hole concentrations exceeding 1019 cm-3 are achieved.

E. Kaminska; E. Przezdziecka; A. Piotrowska; J. Kossut; E. Dynowska; R. Jakiela; W. Dobrowolski; P. Boguslawski; I. Pasternak; E. Lusakowska

2007-01-01

340

Towards efficient p-type doping of ZnO with group-V atoms: N versus As and Sb  

NASA Astrophysics Data System (ADS)

ZnO films were fabricated by oxidation of thin layers of Zn-V compounds and of ZnTe. Controlled p-type doping with N, As, and Sb was obtained. The most efficient doping is observed for ZnO:As in the presence of isoelectronic Te ions. Stable hole concentrations exceeding 1019 cm-3 are achieved.

Kaminska, E.; Prze?dziecka, E.; Piotrowska, A.; Kossut, J.; Dynowska, E.; Jakie?a, R.; Dobrowolski, W.; Bogus?awski, P.; Pasternak, I.; ?usakowska, E.

2007-04-01

341

First-principles calculations reveal the n-type doping difficulties of group IIIA elements in zinc blende ZnS  

NASA Astrophysics Data System (ADS)

At present, the n-type doping behavior of ZnS is still under debate. Some groups have reported that it is difficult to obtain low-resistivity n-type ZnS, while others think it is easy. Our first-principles calculations on the n-type doping of group IIIA elements strongly support the former viewpoint. We find that, although AlS-i, GaS-i, and InS-i are shallow donors, their formation energy is very high at the conduction band minimum (CBM). Thus they can not contribute to the n-type conductivity. Other impurities are all deep donors with high formation energy at the CBM, thus having no contributions either. We believe that our results can provide an understanding of the difficulties of n-type doping of ZnS.

Li, P.; Deng, Sh. H.

2012-05-01

342

K and L-shell X-ray production cross sections for 50-250 keV proton impact on elements with Z = 26-30  

NASA Astrophysics Data System (ADS)

The K and L-shell X-ray production cross sections of Fe, Co, Ni, Cu and Zn elements are measured by 50-250 keV proton impact. The results are compared with Binary Encounter Approximation (BEA), Plane Wave Born Approximation (PWBA) and Energy loss Coulomb repulsion Perturbed Stationary State Relativistic (ECPSSR) theoretical predictions, as well as with experimental data of other authors. The ECPSSR theory agrees well with the K-shell cross section, but it overestimates the L-shell cross section by a maximum factor of about 7. The ECPSSR theory predicts a good trend to the production cross section ratio of the L to K-shell X-ray.

Zhou, Xianming; Zhao, Yongtao; Cheng, Rui; Wang, Yuyu; Lei, Yu; Wang, Xing; Sun, Yuanbo

2013-03-01

343

Calculation of the total Rayleigh scattering cross sections of photons in the energy range of 30-50 keV for Nb and Mo elements  

NASA Astrophysics Data System (ADS)

The total Rayleigh scattering cross sections are calculated in the energy range of 30-50 keV using the modified relativistic form factors (MRFF), non-relativistic form factors (NFF), and relativistic form factors (RFF). Numerical calculations are made for energies above the K-threshold comparisons, for medium-Z elements (Nb and Mo), primarily at small momentum transfers. The integration range is divided into intervals using a modified formula to take into account the smaller scattering angles. The calculated cross sections based on MRFF, NFF, and RFF are presented and compared with the tabulated theoretical values. It is found that the values calculated using the NFF and RFF are smaller than the tabulated values with a ratio of 3-7%. It is also observed that the smallest total Rayleigh scattering cross section values are obtained using the MRFF.

Böke, Aysun

2011-05-01

344

Wafer-scale integration of group III-V lasers on silicon using transfer printing of epitaxial layers  

NASA Astrophysics Data System (ADS)

The hard-drive and electronic industries can benefit by using the properties of light for power transfer and signalling. However, the integration of silicon electronics with lasers remains a challenge, because practical monolithic silicon lasers are not currently available. Here, we demonstrate a strategy for this integration, using an elastomeric stamp to selectively release and transfer epitaxial coupons of GaAs to realize III-V lasers on a silicon substrate by means of a wafer-scale printing process. Low-threshold continuous-wave lasing at a wavelength of 824 nm is achieved from Fabry-Pérot ridge waveguide lasers operating at temperatures up to 100 °C. Single and multi-transverse mode devices emit total optical powers of >60 mW and support modulation bandwidths of >3 GHz. This fabrication strategy opens a route to the low-cost integration of III-V photonic devices and circuits on silicon and other substrates.

Justice, John; Bower, Chris; Meitl, Matthew; Mooney, Marcus B.; Gubbins, Mark A.; Corbett, Brian

2012-09-01

345

Evaluations of proton inelastic mean free paths for 12 elemental solids over the energy range from 0.05 to 10 MeV  

NASA Astrophysics Data System (ADS)

The systematical calculations of the inelastic mean free paths (MFPs) of 0.05-10 MeV protons in 12 elemental solids (Al, Si, Ni, Cu, Mo, Rh, Ag, W, Os, Ir, Pt, Au) have been performed. The calculations are based on the algorithm derived from Ashley’s optical-data model including the higher-order corrections to stopping power (SP) for protons. The prominence and necessity of the higher-order corrections are demonstrated by calculating the proton SPs for the 12 solids using Ashley’s optical-data model and by comparing the calculated SPs with the experimental results, the tabulated values and other corresponding theoretical evaluations. The algorithm of evaluating the proton inelastic MFP is described. In this algorithm, the Barkas-effect correction and the Bloch correction are taken into account, the minimum impact parameter from Lindhard is used in the Barkas-effect correction, and an empirical estimation of a free parameter involved in the Bloch correction to the inelastic MFP is proposed. The evaluated inelastic MFPs of 0.05-10 MeV protons for the 12 solids under two different cases, i.e. the higher-order corrections not being considered and the Barkas-effect correction and the Bloch correction being included, are presented in the tabulated form and are first results for these solids. These numerical results provide an alternative basic data for the Monte Carlo studies on low-energy proton transport in these 12 solids.

Tan, Zhenyu; Xia, Yueyuan

2011-02-01

346

The Distribution of Platinum-Group Elements and Other Chalcophile Elements Among Mineral Phases of the Ni-Cu-PGE Deposit of Creighton Mine, Sudbury, Canada: A Quantitative Mass Balance  

NASA Astrophysics Data System (ADS)

The distribution of PGE and other chalcophile elements among minerals of the Creighton Ore Body of the Sudbury Ni-Cu-PGE deposit has been investigated in order to: 1) better understand the petrogenesis of the ores and 2) aid efficient extraction of the PGE which are recovered as a by-product of mining these ores. A mass balance has been carried out by determining the concentrations of the elements in the; whole rock, the base metal sulphides (BMS) and the associated accessory minerals, including platinum-group minerals (PGM). Calculations show that the BMS host the majority (70-95%) of Co, Os, Pd, Ru and Se, that BMS host some (˜ 50%) Ag, Bi, Cd, Te and Zn but very little (< 20%) Ir, Rh, Re, Pt, Au, As, Pb, Sn and Sb. Discrete PGM and associated accessory minerals (e.g. galena (PbS), sphalerite (Zn(Cd)S), Ag-pentlandite and numerous Bi-Te phases) account for the trace elements that are 'missing' from the sulfide mass balance. Iridum, Rh and Pt are hosted by sulfarsenide-bearing PGM within the BMS. These comprise irarsite (IrAsS)- hollingworthite (RhAsS) cores, containing some Pt, Os and Ru, and Ni-cobaltite (NiCoAsS) rims. Rhenium- phases, such as (CuFe)(ReMoOs)S and RePb(Bi)S, are also hosted by the BMS. Palladium-bearing PGM (michenerite PdBiTe), Pt-bearing PGM (sperrylite PtAs2) and Au (electrum AuAg) are present but rare and are hosted by both BMS and silicates. The Ni-cobaltite is estimated to have equilibrated at 550-600°C, and thus the irarsite-hollingworthite cores probably formed at > 600°C possibly by exsolution from the BMS during cooling. Michenerite was observed to infill fractures in amphibole indicating that some Pd can remobilise during metamorphism and deformation at lower temperatures (˜ 490°C).

Dare, S. A.; Barnes, S.-; Prichard, H. M.; Fisher, P. C.

2009-05-01

347

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

348

ATOMIC AND MOLECULAR PHYSICS: Electronic Stopping Power for 0.05 10 MeV Protons in a Group of Organic Materials  

Microsoft Academic Search

Electronic stopping powers for 0.05-10 MeV protons in a group of organic materials are systematically calculated. The calculations are based on Ashley's dielectric model, and an evaluation approach of optical energy loss function is incorporated into Ashley's model because no experimental optical data are available for most of the organic materials under consideration. The Barkas-effect correction and Bloch correction are

Zhen-Yu Tan; Yue-Yuan Xia; Ming-Wen Zhao; Xiang-Dong Liu; Li-Ming Zhang

2008-01-01

349

Calculations on various total cross-sections of electron impact on group VA - atoms-threshold to 2000 eV  

NASA Astrophysics Data System (ADS)

In this paper we have calculated various total cross-sections of Nitrogen, Phosphorus, Arsenic, Antimony and Bismuth (Group VA-atoms) in the energy range of 15 to 2000 eV. Spherical Complex potential formalism is used to derive total as well as inelastic cross-sections. We have developed CSP-ic method by which we can extract ionization cress-section from the inelastic cross-section. Our results are compared with available theoretical and experimental data.

Joshipura, K. N.; Gangopadhyay, Sumona; Kothari, Harshit N.; Shelat, Foram A.

2009-11-01

350

LBRIG Newsletter: The Trimestrial Publication of the Language by Radio Interest Group, Vol. V, No.1, September, 1976.  

ERIC Educational Resources Information Center

|This issue of the Language by Radio Interest Group newsletter contains: an article by Paul A. Gaeng on his experience as a radio listener, an article by Richard E. Wood on "Radio Peking," and a partial reprint of frequency listings from the January 1976 number. Gaeng reports that, when he was a student in Geneva, he developed skills as a…

Garfinkel, Alan, Ed.; And Others

351

Phospholipids of Clostridium butykum. V. Effects of growth temperature on fatty alk- 1 -enyl ether group, and phospholipid  

Microsoft Academic Search

Many anaerobic bacteria have a high proportion of 1 -alk-1 '-enyl ethers (plasmalogens) among their phospholipids. We have examined the effects of growth temperature on the phospholipid, fatty acid, and alk-1 -enyl group compositions of Clostridium butyricum. When the growth temperature was de- creased from 37°C to 25\\

G. K. Khuller; Howard Goldfine

352

78 FR 12873 - United States v. Apple, Inc., Hachette Book Group, Inc., Harpercollins Publishers L.L.C...  

Federal Register 2010, 2011, 2012, 2013

...meetings with Apple, Penguin Group CEO John Makinson had a breakfast meeting at a London hotel with the CEO of another Publisher...other efforts to conceal their activities, Mr. Makinson's breakfast companion wrote to his U.S. subordinate that he...

2013-02-25

353

77 FR 77094 - United States v. Apple, Inc., Hachette Book Group, Inc., HarperCollins Publishers L.L.C...  

Federal Register 2010, 2011, 2012, 2013

...meetings with Apple, Penguin Group CEO John Makinson had a breakfast meeting at a London hotel with the CEO of another Publisher...other efforts to conceal their activities, Mr. Makinson's breakfast companion wrote to his U.S. subordinate that he...

2012-12-31

354

HRTEM-AEM-HAADF-STEM study of platinum-group elements within a mantle-derived Cr spinel (Lherz; North-Eastern Pyrenees, France)  

NASA Astrophysics Data System (ADS)

As platinum group elements (PGE) like Ru, Os, Ir and Rh have appropriate charge and ionic radii to substitute the major cations in the spinel structure, Cr-spinel is one of the potential minerals that can fractionate such elements during the partial melting and fractional crystallization. However, whether PGE occur in solid solution or are physically collected as poly-metallic clusters of atoms on spinel grain boundaries is a central issue for PGE geochemistry. A PGE-bearing Cr-spinel separated from one harzburgite sample from Lherz has been analyzed by Transmission, Analytical and Scanning-Transmission Electron Microscopy (TEM-AEM-STEM). Our analyses did not reveal any exsolution/cluster feature at the nanometric scale, except for Ir, which is concentrated as Ir-bearing lamellar rutile, about 100 nm width. Rutile appears to have enhanced unmixing of Ir from the spinel structure. The DCr spinel/silicate melt partition coefficients estimated from the Lherz Cr-spinel (Ir = 32 ± 0.7; Os = 28 ± 6; Ru = 12.5 ± 2; Pt = 1.5 ± 0.2; Pd = 0.2 ± 0.05) may be appropriate for modelling the behavior of PGE in sulfur-undersaturated melting processes of the shallow upper mantle, while being lower than those derived from experiments and natural ultramafic melts.

Ferraris, Cristiano; Lorand, Jean-Pierre

2008-11-01

355

Multireference - M?ller-Plesset Perturbation Theory Results on Levels and Transition Rates in Al-like Ions of Iron Group Elements  

SciTech Connect

Ground configuration and low-lying levels of Al-like ions contribute to a variety of laboratory and solar spectra, but the available information in databases are neither complete not necessarily correct. We have performed multireference Moeller-Plesset perturbation theory calculations that approach spectroscopic accuracy in order to check the information that databases hold on the 40 lowest levels of Al-Like ions of iron group elements (K through Ge), and to provide input for the interpretation of concurrent experiments. Our results indicate problems of the database holdings on the levels of the lowest quartet levels in the lighter elements of the range studied. The results of our calculations of the decay rates of five long-lived levels (3s{sup 2}3p {sup 2}p{sup o}{sub 3/2}, 3s3p{sup 2} {sup 4}P{sup o} J and 3s3p3d {sup 4}F{sup o}{sub 9/2}) are compared with lifetime data from beam-foil, electron beam ion trap and heavy-ion storage ring experiments.

Santana, J A; Ishikawa, Y; Tr?abert, E

2009-02-19

356

Relativistic effects on the electronic structure and volatility of group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs.  

PubMed

The influence of relativistic effects on properties and volatility of the group-8 tetroxides MO4, where M=Ru, Os, and element 108, Hs, was studied on the basis of results of the fully relativistic (four component) and nonrelativistic density functional theory calculations. Relativistic effects were shown to increase bond strengths and decrease bond lengths in these molecules. They are responsible for a decrease in molecular polarizabilities and an increase in ionization potentials. The effects are much stronger in HsO4 than in the lighter congeners. Relativistic effects were also shown to slightly decrease dispersion interaction energies of RuO4, OsO4, and HsO4 with an inert (quartz or silicon nitride) surface, i.e., they increase volatility of these compounds as studied in the "one-atom-at-a-time" gas-phase chromatography experiments. They do, however, not influence the trend in group 8: both relativistically and nonrelativistically, volatility should change as RuO4

Pershina, V; Bastug, T; Fricke, B

2005-03-22

357

Ectomycorrhizal influence on particle size, surface structure, mineral crystallinity, functional groups, and elemental composition of soil colloids from different soil origins.  

PubMed

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

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

2013-05-23

358

ATOMIC AND MOLECULAR PHYSICS: Electronic Stopping Power for 0.05 10 MeV Protons in a Group of Organic Materials  

NASA Astrophysics Data System (ADS)

Electronic stopping powers for 0.05-10 MeV protons in a group of organic materials are systematically calculated. The calculations are based on Ashley's dielectric model, and an evaluation approach of optical energy loss function is incorporated into Ashley's model because no experimental optical data are available for most of the organic materials under consideration. The Barkas-effect correction and Bloch correction are included. The proton stopping powers for the considered organic materials except for mylar in the energy range from 0.05 to 10MeV are presented for the first time. The results may be useful for studies of various radiation effects in these materials and for space research.

Tan, Zhen-Yu; Xia, Yue-Yuan; Zhao, Ming-Wen; Liu, Xiang-Dong; Zhang, Li-Ming

2008-06-01

359

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

Microsoft Academic Search

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

2007-01-01

360

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

Microsoft Academic Search

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

Roland Pässler

2007-01-01

361

Opticheskie parametry tripletnoj fokusiruyushchej sistemy i ee dejstvie v stigmaticheskom rezhime. (Focusing properties of a three-element quadrupole lens system and its stigmatic focusing behaviour).  

National Technical Information Service (NTIS)

The focusing properties of a three-element quadrupole lens system (triplet) have been studied in its general thick-lens form, and analytical expressions of corresponding matrix elements have been obtained. A graphical method has been utilized to determine...

Y. Zafar

1991-01-01

362

SCALE radiation shielding V and V package  

SciTech Connect

Verification and validation (V and V) are essential elements of software quality assurance (QA) for computer codes that are used for scientific calculations. The sponsors of the SCALE code system have required a QA plan and a V and V plan. For purposes of validating and verifying the SCALE shielding codes, a set of problems has been assembled and tested.

Emmett, M.B.; Bowman, S.M.; Broadhead, B.L.

1997-12-01

363

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

364

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

USGS Publications Warehouse

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

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

2006-01-01

365

Mechanisms for the reactions of group 10 transition metal complexes with metal-group 14 element bonds, Bbt(Br)E?M(PCy3)2 (E = C, Si, Ge, Sn, Pb; M = Pd and Pt).  

PubMed

The electronic structures of the Bbt(Br)E?M(PCy(3))(2) (E = C, Si, Ge, Sn, Pb and M = Pt, Pd) complexes and their potential energy surfaces for the formation and water addition reactions were studied using density functional theory (B3LYP/LANL2DZ). The theoretical evidence suggests that the bonding character of the E?M double bond between the six valence-electron Bbt(Br)E: species and the 14 valence-electron (PCy(3))(2)M complexes has a predominantly high s-character. That is, on the basis of the NBO, this theoretical study indicates that the ?-donation from the E element to the M atom prevails. Also, theoretical computations suggest that the relative reactivity decreases in the order: Bbt(Br)C?M(PCy(3))(2) > Bbt(Br)Si?M(PCy(3))(2) > Bbt(Br)Ge?M(PCy(3))(2) > Bbt(Br)Sn?M(PCy(3))(2) > Bbt(Br)Pb?M(PCy(3))(2), irrespective of whether M = Pt or M = Pd is chosen. Namely, the greater the atomic weight of the group 14 atom (E), the larger is the atomic radius of E and the more stable is its Bbt(Br)E?M(PCy(3))(2) doubly bonded species toward chemical reactions. The computational results show good agreement with the available experimental observations. The theoretical results obtained in this work allow a number of predictions to be made. PMID:23339483

Liao, Wei-Hung; Ho, Pei-Yun; Su, Ming-Der

2013-01-22

366

L-Ficolin and Capsular Polysaccharide-Specific IgG in Cord Serum Contribute Synergistically to Opsonophagocytic Killing of Serotype III and V Group B Streptococci  

PubMed Central

Group B streptococci (GBS; Streptococcus agalactiae) are the most common cause of neonatal sepsis and meningitis. Serotype-specific IgG antibody is known to protect neonates against GBS infections by promoting opsonophagocytosis. The L-ficolin-mediated lectin pathway of the complement is also a potential mechanism for opsonization of GBS, because L-ficolin activates the complement after binding to serotype Ib, III, V, VI, and VIII GBS. In the present study, we investigated how L-ficolin and serotype-specific IgG in cord sera contribute to opsonophagocytic killing of GBS. Neither L-ficolin nor serotype-specific IgG concentrations correlated with C3b deposition on serotype Ib and VI GBS, suggesting L-ficolin- and serotype-specific IgG-independent mechanisms of complement activation. The percentage of serotype VIII GBS killed was high regardless of the concentration of L-ficolin and IgG. In contrast, L-ficolin and serotype-specific IgG can each initiate C3b deposition on serotype III and V GBS and promote phagocytosis by polymorphonuclear leukocytes, but L-ficolin and serotype-specific IgG together promote opsonophagocytic killing to a greater extent than does either alone in vitro. This synergy was observed when serotype III-specific IgG concentrations were between 1 and 6 ?g/ml and when serotype V-specific IgG concentrations were between 2 and 5 ?g/ml. Concentrations of serotype III-specific IgG in cord blood above 7 ?g/ml are considered protective for neonates colonized with GBS, but most neonates with IgG levels of less than 7 ?g/ml do not develop GBS infections. The data presented here suggest that L-ficolin enhances opsonophagocytosis of serotype III and V GBS when serotype-specific IgG alone is suboptimal for protection.

Fujieda, Mioko; Aoyagi, Youko; Matsubara, Kousaku; Takeuchi, Yasuhito; Fujimaki, Wakae; Matsushita, Misao; Bohnsack, John F.

2012-01-01

367

Specific roles for Group V secretory PLA? in retinal iron-induced oxidative stress. Implications for age-related macular degeneration.  

PubMed

Iron accumulation and oxidative stress are hallmarks of retinas from patients with age-related macular degeneration (AMD). We have previously demonstrated that iron-overloaded retinas are a good in vitro model for the study of retinal degeneration during iron-induced oxidative stress. In this model we have previously characterized the role of cytosolic phospholipase A2 (cPLA2) and calcium-independent isoform (iPLA2). The aim of the present study was to analyze the implications of Group V secretory PLA2 (sPLA2), another member of PLA2 family, in cyclooxygenase (COX)-2 and nuclear factor kappa B (NF-?B) regulation. We found that sPLA2 is localized in cytosolic fraction in an iron concentration-dependent manner. By immunoprecipitation (IP) assays we also demonstrated an increased association between Group V sPLA2 and COX-2 in retinas exposed to iron overload. However, COX-2 activity in IP assays was observed to decrease in spite of the increased protein levels observed. p65 (RelA) NF-?B levels were increased in nuclear fractions from retinas exposed to iron. In the presence of ATK (cPLA2 inhibitor) and YM 26734 (sPLA2 inhibitor), the nuclear localization of both p65 and p50 NF-?B subunits was restored to control levels in retinas exposed to iron-induced oxidative stress. Membrane repair mechanisms were also analyzed by studying the participation of acyltransferases in phospholipid remodeling during retinal oxidation stress. Acidic phospholipids, such as phosphatidylinositol (PI) and phosphatidylserine (PS), were observed to show an inhibited acylation profile in retinas exposed to iron while phosphatidylethanolamine (PE) showed the opposite. The use of PLA2 inhibitors demonstrated that PS is actively deacylated during iron-induced oxidative stress. Results from the present study suggest that Group V sPLA2 has multiple intracellular targets during iron-induced retinal degeneration and that the specific role of sPLA2 could be related to inflammatory responses by its participation in NF-?B and COX-2 regulation. PMID:23791636

Rodríguez Diez, G; Sánchez Campos, S; Giusto, N M; Salvador, G A

2013-06-18

368

A calibration method for group V fluxes and impact of V/III flux ratio on the growth of InAs/InAsSb type-II superlattices by molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

A calibration method for group V fluxes is demonstrated for the growth of InAsxSb1?x alloys and strain-balanced InAs/InAsxSb1?x superlattices on GaSb substrates by molecular beam epitaxy for IR optoelectronic device applications. The structural and optical properties of these structures grown with varying V/III flux ratios are investigated using several characterization methods, including X-ray diffraction (XRD), photoluminescence (PL), and reflection high energy electron diffraction. Samples grown at 450°C with Sb/In flux ratios from 1.0 to 2.0 and As/In flux ratios from 1.2 to 2.5 lead to Sb mole fractions ranging from 0.078 to 0.34. High structural and optical quality superlattices for Sb mole fractions up to 0.34 are verified by XRD and low-temperature PL measurements. When varying both Sb mole fraction and period, superlattice structures are demonstrated with low-temperature emission wavelengths ranging from 3.6 to 7.1?m.

Li, Hua; Liu, Shi; Cellek, Oray O.; Ding, Ding; Shen, Xiao-Meng; Steenbergen, Elizabeth H.; Fan, Jin; Lin, Zhiyuan; He, Zhao-Yu; Zhang, Qiang; Webster, Preston T.; Johnson, Shane R.; Ouyang, Lu; Smith, David J.; Zhang, Yong-Hang

2013-09-01

369

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

370

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

PubMed

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

Boulyga, Sergei F; Heumann, Klaus G

2005-10-19

371

Relatively Long-Lived Dubnium Isotopes and Chemical Identification of Superheavy Elements  

SciTech Connect

The present study has been performed within the framework of experiments aimed at the investigation of chemical properties of long-lived Db isotopes in aqueous solutions. The isocratic anion exchange separations of group V elements in the solutions containing HF have been considered. Parameters of separation of dubnium homologues (Pa, Nb and Ta) in HF/HNO{sub 3} mixed solutions have been optimized. The procedure of separation of group V elements from multicomponent system has been suggested.

Tereshatov, E. E.; Voronyuk, M. G.; Starodub, G. Ya.; Petrushkin, O. V.; Dmitriev, S. N. [Flerov Laboratory of Nuclear Reactions (FLNR), JINR, Dubna RU-141980 (Russian Federation); Bruchertseifer, H. [Paul Scherrer Institute (PSI), Villigen CH-5232 (Switzerland)

2010-04-30

372

Assessment of Degree of Applicability of Benchmarks for Gadolinium Using KENO V.a and the 238-Group SCALE Cross-Section Library  

SciTech Connect

A review of the degree of applicability of benchmarks containing gadolinium using the computer code KENO V.a and the gadolinium cross sections from the 238-group SCALE cross-section library has been performed for a system that contains {sup 239}Pu, H{sub 2}O, and Gd{sub 2}O{sub 3}. The system (practical problem) is a water-reflected spherical mixture that represents a dry-out condition on the bottom of a sludge receipt and adjustment tank around steam coils. Due to variability of the mixture volume and the H/{sup 239}Pu ratio, approximations to the practical problem, referred to as applications, have been made to envelop possible ranges of mixture volumes and H/{sup 239}Pu ratios. A newly developed methodology has been applied to determine the degree of applicability of benchmarks as well as the penalty that should be added to the safety margin due to insufficient benchmarks.

Goluoglu, S.

2003-12-01

373

Point Groups  

NSDL National Science Digital Library

This exercise involves identifying symmetry in crystals and using that information to assign crystals to crystal systems and point groups. Students examine cardboard models and wooden blocks and fill their symmetry elements into a table. Then they figure out what what crystal system and point group each sample belongs to and fill in another table.

Perkins, Dexter

374

Proton stopping power in a group of bioorganic compounds over the energy range of 0.05 10 MeV  

NASA Astrophysics Data System (ADS)

The systematic calculations of the stopping powers (SPs) for 0.05 10 MeV protons in a group of 10 important bioorganic compounds, i.e. DNA, five bases, three fatty acids and cellulose, have been performed. The calculations are based on the dielectric model of Ashley and on an evaluation of optical energy loss function (OELF) for the bioorganic compounds considered, most of which have no available optical data. Higher-order corrections, Barkas-effect correction and Bloch correction, are included and a concise form of SP calculation corresponding to Barkas-effect is presented by incorporating the evaluated OELF. Especially, the dependences of SP calculations on the two choices of the minimum impact parameter a are analyzed in detail, and hence an appropriate parameter a is determined for organic media. For the tested organic compounds the proton SPs calculated by use of the determined a are in excellent agreement with the tabulated values based on experimental data. The presented data are the first results of the proton SPs for the 10 bioorganic compounds in the energy range from 0.05 to 10 MeV, and might be useful for studies of various radiation effects in these materials.

Tan, Zhenyu; Xia, Yueyuan; Zhao, Mingwen; Liu, Xiangdong

2006-07-01

375

M -shell ionization of heavy elements by 0.1 1.0 MeV/amu 1,2 H and 3,4 He ions  

NASA Astrophysics Data System (ADS)

The M -shell ionization in high- Z atoms by low-energy light H11 , H12 , He23 , and He24 ions have been studied systematically in the energy range 0.1-1.0MeV/amu in order to verify the available theoretical approaches describing the M -shell ionization by charged particles in asymmetric collisions. The present low-energy data, combined with our earlier results reported for M -shell ionization by hydrogen and helium ions for higher energies, form a systematic experimental basis to test the theoretical predictions of M -shell ionization based on the plane-wave Born approximation (PWBA), the semiclassical approximation (SCA), and the binary-encounter approximation (BEA). In the PWBA based approaches the energy loss (E), Coulomb deflection (C), perturbed stationary state (PSS), and relativistic (R) effects were considered within the ECPSSR theory and its recent modification, called the ECUSAR theory, in which a description of the PSS effect was corrected to account for the united- and separated-atom (USA) electron binding energy limits. In the SCA calculations with relativistic wave functions the binding effect was included only in the limiting cases of separated-atom and united-atom limits. Possible contribution of the electron capture, multiple ionization, and recoil ionization to the M -shell vacancy production, which is dominated for light ions impact by direct single ionization process, are also discussed. The universal scaling of measured M -shell x-ray production and ionization cross sections was investigated in detail. Using the present data the isotopic effect has been studied by comparing the measured M -shell ionization cross-section ratios for equal-velocity hydrogen H11 and H12 as well as helium He23 and He24 isotopes. In addition, the ratios of measured ionization cross sections for H12 and He24 were used to investigate the role of the binding effect. The present results are of practical importance for the application of particle-induced x-ray emission technique in trace element studies.

Pajek, M.; Bana?, D.; Braziewicz, J.; Czarnota, M.; Bie?kowski, A.; Jaskó?a, M.; Korman, A.; Trautmann, D.; Lapicki, G.

2006-01-01

376

Intramolecular non-bonded interactions between oxygen and group VIA elements. An ab initio molecular orbital and density functional theory investigation of the structures of HX–CH 2–CHO (X=S, Se and Te)  

Microsoft Academic Search

Non-bonded interactions between the group VIA elements and oxygen atoms play roles in numerous chemical processes, however, the geometries and energetics of these interactions are not yet well defined. Ab initio molecular orbital and density functional methods have been used to study the potential energy surfaces of the substituted acetaldehydes, HX–CH2–CH?O, where X is one of the Group VIA chalcophiles

George D. Markham; Cindy L. Bock; Mendel Trachtman; Charles W. Bock

1999-01-01

377

Distribution of groups I and II elements between liquidus phases of fluorine-saturated Si-Al-Na-K-Li-H-O system  

Microsoft Academic Search

Experimental data allow modeling the behavior of the named elements during formation of fluorine- saturated leucocratic rocks\\u000a of silicic and alkaline compositions. The distribution of alkaline and alkaliearth elements is discussed at equilibrium between\\u000a the silica-alumina melt with fluoride phases (crystalline and liquid) and with feldspar. Cryolite crystals form during saturation\\u000a of silica-alumina melt of normal alkalinity with fluorine. Continuous

E. N. Gramenitskii; T. I. Shchekina; Ya. O. Alfer’eva; E. S. Zubkov

2008-01-01

378

Universal mechanism for ion-induced nanostructure formation on III-V compound semiconductor surfaces  

SciTech Connect

We have examined the formation of nanostructures on ion-irradiated compound semiconductor surfaces. We computed the ion doses needed to fully deplete group V elements from the surfaces. These group V depletion doses are in good agreement with the measured threshold ion doses for nucleation of group III-rich nanostructures on a wide variety of III-V compound semiconductor surfaces. Since the group V depletion doses decrease with increasing sputtering yield, these results suggest a universal nanostructure formation mechanism which depends upon the total sputtering yield of each III-V compound.

Kang, M.; Wu, J. H.; Huang, S.; Warren, M. V.; Jiang, Y.; Robb, E. A.; Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)

2012-08-20

379

Experimental measurements of K X-ray production cross-sections and yields for the elements with 58 ?slant Z ?slant 64 at 123.6 keV photon energy  

NASA Astrophysics Data System (ADS)

Considering the importance of the K X-ray production cross-sections (?_{Ki}^x) as well as the K shell fluorescence yields (?K) for the determination of element concentrations in a given material, we have measured them experimentally for the elements Ce, Pr, Nd, Sm, Eu and Gd using photons at 123.6 keV from a 57Co radioisotope source. Furthermore, the K X-rays intensity ratios (K?/K?) for these elements have been investigated. The characteristic K X-rays emitted by the target were detected by a high-resolution with an energy resolution of 160 eV full with at half-maximum ( FWHM) at 5.96 keV. The experimental results of K X-ray production cross-sections were compared with theoretically predicted values based on relativistic Hartree-Slater and Hartree-Fock theories. Similarly, the measured K shell fluorescence yields/cross-sections and the K X-rays intensity ratios were compared with the theoretical values. In most cases, there is an agreement between the experimental and theoretical data within the experimental uncertainties.

Ertu?ral, B.

2007-08-01

380

KENO-V code  

SciTech Connect

The KENO-V code is the current release of the Oak Ridge multigroup Monte Carlo criticality code development. The original KENO, with 16 group Hansen-Roach cross sections and P/sub 1/ scattering, was one ot the first multigroup Monte Carlo codes and it and its successors have always been a much-used research tool for criticality studies. KENO-V is able to accept large neutron cross section libraries (a 218 group set is distributed with the code) and has a general P/sub N/ scattering capability. A supergroup feature allows execution of large problems on small computers, but at the expense of increased calculation time and system input/output operations. This supergroup feature is activated automatically by the code in a manner which utilizes as much computer memory as is available. The primary purpose of KENO-V is to calculate the system k/sub eff/, from small bare critical assemblies to large reflected arrays of differing fissile and moderator elements. In this respect KENO-V neither has nor requires the many options and sophisticated biasing techniques of general Monte Carlo codes.

Cramer, S.N.

1984-01-01

381

Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma-mass spectrometry: evidence for the release of platinum group and anthropogenic metals from motor vehicles.  

PubMed

Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma-mass spectrometry (DRC-q-ICP-MS). Average Rh, Pd and Pt concentrations were 152±52, 770±208 and 529±130 ng g(-1) respectively in tunnel dusts while they varied between 6 and 8 ng g(-1), 10 and 88 ng g(-1) and 35 and 131 ng g(-1) in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However, all other elements including rare earths most likely arose from weathering, erosion and resuspension of crustal material. These are the first such detailed measurements in Houston, the largest city in TX and fourth largest in the United States. We posit that such investigations will assist in better understanding PGE concentrations in urban environments while providing elemental data necessary to better understand anthropogenic influences on their biogeochemical cycling. PMID:22713911

Spada, Nicholas; Bozlaker, Ayse; Chellam, Shankararaman

2012-05-24

382

Groups IV, V, and X phospholipases A2s in human neutrophils: role in eicosanoid production and gram-negative bacterial phospholipid hydrolysis.  

PubMed

The bacterial tripeptide formyl-Met-Leu-Phe (fMLP) induces the secretion of enzyme(s) with phospholipase A(2) (PLA(2)) activity from human neutrophils. We show that circulating human neutrophils express groups V and X sPLA(2) (GV and GX sPLA(2)) mRNA and contain GV and GX sPLA(2) proteins, whereas GIB, GIIA, GIID, GIIE, GIIF, GIII, and GXII sPLA(2)s are undetectable. GV sPLA(2) is a component of both azurophilic and specific granules, whereas GX sPLA(2) is confined to azurophilic granules. Exposure to fMLP or opsonized zymosan results in the release of GV but not GX sPLA(2) and most, if not all, of the PLA(2) activity in the extracellular fluid of fMLP-stimulated neutrophils is due to GV sPLA(2). GV sPLA(2) does not contribute to fMLP-stimulated leukotriene B(4) production but may support the anti-bacterial properties of the neutrophil, because 10-100 ng per ml concentrations of this enzyme lead to Gram-negative bacterial membrane phospholipid hydrolysis in the presence of human serum. By use of a recently described and specific inhibitor of cytosolic PLA(2)-alpha (group IV PLA(2)alpha), we show that this enzyme produces virtually all of the arachidonic acid used for the biosynthesis of leukotriene B(4) in fMLP- and opsonized zymosan-stimulated neutrophils, the major eicosanoid produced by these pro-inflammatory cells. PMID:11741884

Degousee, Norbert; Ghomashchi, Farideh; Stefanski, Eva; Singer, Alan; Smart, Brian P; Borregaard, Niels; Reithmeier, Reinhardt; Lindsay, Thomas F; Lichtenberger, Cornelia; Reinisch, Walter; Lambeau, Gerard; Arm, Jonathan; Tischfield, Jay; Gelb, Michael H; Rubin, Barry B

2001-12-06

383

A novel group of families of short interspersed repetitive elements (SINEs) in Xenopus: evidence of a specific target site for DNA-mediated transposition of inverted-repeat SINEs.  

PubMed

We have isolated from Xenopus borealis members of a family of short interspersed repetitive elements (SINEs) that we have termed Xbr. Xbr elements are also present in other Xenopus genomes and are typically framed by 46 bp terminal inverted repeats (TIRs). These TIRs and those of two previously described families of inverted-repeat SINEs from X. laevis begin with the sequence TTAAAGGRR. Knowledge of this consensus, termed the T2 motif, allowed us to define four previously uncharacterized families of inverted-repeat SINEs from Xenopus database sequences. We estimate that the group of seven SINE families that possess the T2 motif accounts for about 10% of all X. laevis SINEs. Novel evidence for the transposition of inverted-repeat SINEs is provided: (1) by examples of the presence/absence of T2 elements at corresponding locations in either duplicated genes or pseudotetraploid gene homeologues; and (2) by the existence of contiguous elements from different T2 families that are joined precisely by their TIRs. These examples provide novel evidence for a DNA-mediated mechanism of T2 element transposition. They also show that the tetranucleotide, TTAA, which flanks integrated elements on both sides and is present once at unoccupied sites, is the obligate target site for T2 insertion. The use of a specific sequence as a target site for SINE insertion is unexpected, although such specificity is exhibited by a limited number of larger transposable elements that encode their own transposase. The clear evidence for DNA-mediated transposition provided by T2 elements demonstrates that the evolution and maintenance of SINE families in vertebrate genomes results from two distinctive mechanisms. PMID:7752242

Unsal, K; Morgan, G T

1995-05-12

384

Transcriptional regulation of T-type calcium channel CaV3.2: bi-directionality by early growth response 1 (Egr1) and repressor element 1 (RE-1) protein-silencing transcription factor (REST).  

PubMed

The pore-forming Ca(2+) channel subunit Ca(V)3.2 mediates a low voltage-activated (T-type) Ca(2+) current (I(CaT)) that contributes pivotally to neuronal and cardiac pacemaker activity. Despite the importance of tightly regulated Ca(V)3.2 levels, the mechanisms regulating its transcriptional dynamics are not well understood. Here, we have identified two key factors that up- and down-regulate the expression of the gene encoding Ca(V)3.2 (Cacna1h). First, we determined the promoter region and observed several stimulatory and inhibitory clusters. Furthermore, we found binding sites for the transcription factor early growth response 1 (Egr1/Zif268/Krox-24) to be highly overrepresented within the Ca(V)3.2 promoter region. mRNA expression analyses and dual-luciferase promoter assays revealed that the Ca(V)3.2 promoter was strongly activated by Egr1 overexpression in vitro and in vivo. Subsequent chromatin immunoprecipitation assays in NG108-15 cells and mouse hippocampi confirmed specific Egr1 binding to the Ca(V)3.2 promoter. Congruently, whole-cell I(CaT) values were significantly larger after Egr1 overexpression. Intriguingly, Egr1-induced activation of the Ca(V)3.2 promoter was effectively counteracted by the repressor element 1-silencing transcription factor (REST). Thus, Egr1 and REST can bi-directionally regulate Ca(V)3.2 promoter activity and mRNA expression and, hence, the size of I(CaT). This mechanism has critical implications for the regulation of neuronal and cardiac Ca(2+) homeostasis under physiological conditions and in episodic disorders such as arrhythmias and epilepsy. PMID:22431737

van Loo, Karen M J; Schaub, Christina; Pernhorst, Katharina; Yaari, Yoel; Beck, Heinz; Schoch, Susanne; Becker, Albert J

2012-03-19

385

A Unique Group of Virus-Related, Genome-Integrating Elements Found Solely in the Bacterial Family Thermaceae and the Archaeal Family Halobacteriaceae? †  

PubMed Central

Viruses SH1 and P23-77, infecting archaeal Haloarcula species and bacterial Thermus species, respectively, were recently designated to form a novel viral lineage. In this study, the lineage is expanded to archaeal Halomicrobium and bacterial Meiothermus species by analysis of five genome-integrated elements that share the core genes with these viruses.

Jalasvuori, Matti; Pawlowski, Alice; Bamford, Jaana K. H.

2010-01-01

386

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

NASA Astrophysics Data System (ADS)

Layered intrusions preserve magmatic inclusions containing hydrous halide melt phases composed of transition metal chlorides with less than 5 wt% H2O. Previous attempts at measuring platinum-group element (PGE) solubility in such high salinity volatiles through the analysis of synthetic fluid inclusions have shown that, although the PGE appear to be highly soluble at geologically-realistic conditions, it is difficult to determine if trapped fluids represent equilibrium fluid compositions. Wide ranges in trapped metal content may result from (i) premature formation of fluid inclusions owing to rapid rates of silicate mineral healing (i.e., hours at magmatic conditions in a saline fluid), (ii) premature entrapment of fluids in which the approach to equilibrium metal solubility requires the generation of the metal-complexing ligands (e.g., HCl) from a slow fluid-mineral or fluid- melt buffer reaction, (iii) the dissolution and reprecipitation of PGE in opened inclusions due to subtle temperature or chemical gradients in run capsules, or (iv) heterogeneous fluid compositions due to the presence of PGE micronuggets or colloids that are more abundant near metal-fluid or metal-buffer interfaces. To circumvent some of the problems associated with synthetic inclusion methods, the solubility of platinum in a hydrous salt melt (S-free; 75 wt% CaCl2+MgCl2, 25 wt% H2O) was investigated at elevated T (700°C) and low crustal pressure. The salt melts were reacted with PtAs2 (natural sperrylite) in Pt capsules buffered at an oxygen fugacity of FMQ-1 using a mixed gas buffer and by the solid mineral assemblage tremolite- diopside-enstatite-quartz which fixes the concentration of relevant metal-complexing ligands at run conditions. Salt melts were trapped (simultaneously) in the matrix of a quartz trap (granulated natural quartz partially isolated in a smaller gold capsule) and in synthetic melt inclusions trapped in pre-fractured quartz. After quenching, the melt inclusions and quartz trap material (in a frozen state) were analyzed by laser ablation ICP-MS (ETH Zürich). Platinum solubility in the presence of the mineral sperrylite is in the low ppm range. Analysis of different portions of the quartz traps using a 90 micron pit size yielded relatively consistent platinum concentrations of 4.9 ppm +/- 1.4 ppm (2 sigma, n=28) with a routine detection limit of 80-90 ppb for Pt. Analyses of traps at different experiments run durations indicate that Pt equilibrium is reached after 150 hours and is approached from over- saturation. Based on these observations, it is suggested that the measured concentrations are representative of Pt solubility at run conditions and that the laser sampling size sufficiently overcomes local heterogeneity in the distribution of Pt quench products. By contrast, Pt concentrations in hydrosaline melt inclusions from different areas of a 3 mm x 10 mm quartz cylinder range from below detection limits (0.2 ppm) to 4.7 ppm (n=102). The range in observed metal concentrations in the fluid inclusions varies between different areas in the quartz cylinder. The data demonstrates that measurements of PGE solubility in hydrous salt melt phases using a frozen quartz trap eliminates some uncertainties concerning the true equilibrum metal solubility that are associated with synthetic inclusion methods. Additionally, the detection limits achievable using the quartz trap method are up to an order of magnitude lower than for synthetic inclusions, owing to the much higher mass of halide melt that may be analyzed in a single ablation.

Hanley, J. J.

2007-12-01

387

Describing Groups  

Microsoft Academic Search

Two ways of describing a group are considered.\\u000a1. A group is finite-automaton presentable\\u000aif its elements can be represented by strings over a finite alphabet,\\u000ain such a way that the set of representing strings and\\u000athe group operation can be recognized by finite automata.\\u000a2. An infinite f.g. group is quasi-finitely axiomatizable\\u000aif there is a description consisting

André Nies

2007-01-01

388

ATTED-II: a database of co-expressed genes and cis elements for identifying co-regulated gene groups in Arabidopsis.  

PubMed

Publicly available database of co-expressed gene sets would be a valuable tool for a wide variety of experimental designs, including targeting of genes for functional identification or for regulatory investigation. Here, we report the construction of an Arabidopsis thaliana trans-factor and cis-element prediction database (ATTED-II) that provides co-regulated gene relationships based on co-expressed genes deduced from microarray data and the predicted cis elements. ATTED-II (http://www.atted.bio.titech.ac.jp) includes the following features: (i) lists and networks of co-expressed genes calculated from 58 publicly available experimental series, which are composed of 1388 GeneChip data in A.thaliana; (ii) prediction of cis-regulatory elements in the 200 bp region upstream of the transcription start site to predict co-regulated genes amongst the co-expressed genes; and (iii) visual representation of expression patterns for individual genes. ATTED-II can thus help researchers to clarify the function and regulation of particular genes and gene networks. PMID:17130150

Obayashi, Takeshi; Kinoshita, Kengo; Nakai, Kenta; Shibaoka, Masayuki; Hayashi, Shinpei; Saeki, Motoshi; Shibata, Daisuke; Saito, Kazuki; Ohta, Hiroyuki

2006-11-27

389

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

390

Systematics of rare earth elements, Th, Hf, Sc, Co, Cr, and Ni in the vendian pelitic rocks of the Serebryanka and Sylvitsa groups from the western slope of the Central Urals: A tool for monitoring provenance composition  

Microsoft Academic Search

This paper presents the first data on the systematics of rare earth elements (REE), Th, Hf, Sc, Co, Cr, and Ni and the Nd\\u000a model ages of fine-grained aluminosilicate clastic rocks of the Serebryanka and Sylvitsa groups of the Vendian from the Kvarkushsko-Kamennogorskii\\u000a meganticlinorium (western slope of the Central Urals). It was found that the REE distribution patterns of shales

A. V. Maslov; Yu. L. Ronkin; M. T. Krupenin; G. A. Petrov; A. Yu. Kornilova; O. P. Lepikhina; O. Yu. Popova

2006-01-01

391

Platinum-group elements, S, Se and Cu in highly depleted abyssal peridotites from the Mid-Atlantic Ocean Ridge (ODP Hole 1274A): Influence of hydrothermal and magmatic processes  

NASA Astrophysics Data System (ADS)

Highly depleted harzburgites and dunites were recovered from ODP Hole 1274A, near the intersection between the Mid-Atlantic Ocean Ridge and the 15°20'N Fracture Zone. In addition to high degrees of partial melting, these peridotites underwent multiple episodes of melt-rock reaction and intense serpentinization and seawater alteration close to the seafloor. Low concentrations of Se, Cu and platinum-group elements (PGE) in harzburgites drilled at around 35-85 m below seafloor are consistent with the consumption of mantle sulfides after high degrees (>15-20 %) of partial melting and redistribution of chalcophile and siderophile elements into PGE-rich residual microphases. Higher concentrations of Cu, Se, Ru, Rh and Pd in harzburgites from the uppermost and lowest cores testify to late reaction with a sulfide melt. Dunites were formed by percolation of silica- and sulfur-undersaturated melts into low-Se harzburgites. Platinum-group and chalcophile elements were not mobilized during dunite formation and mostly preserve the signature of precursor harzburgites, except for higher Ru and lower Pt contents caused by precipitation and removal of platinum-group minerals. During serpentinization at low temperature (<250 °C) and reducing conditions, mantle sulfides experienced desulfurization to S-poor sulfides (mainly heazlewoodite) and awaruite. Contrary to Se and Cu, sulfur does not record the magmatic evolution of peridotites but was mostly added in hydrothermal sulfides and sulfate from seawater. Platinum-group elements were unaffected by post-magmatic low-temperature processes, except Pt and Pd that may have been slightly remobilized during oxidative seawater alteration.

Marchesi, Claudio; Garrido, Carlos J.; Harvey, Jason; González-Jiménez, José María; Hidas, Károly; Lorand, Jean-Pierre; Gervilla, Fernando

2013-11-01

392

Organoantimony compounds with element—element bonds  

Microsoft Academic Search

In this article an overview is given on recent developments in the chemistry of organometallic compounds with antimony—antimony bonds or bonds between antimony atoms and elements of the groups 14 and 16.

H. J. Breunig; R. Rösler

1997-01-01

393

The effect of hydrogen as a temporary alloying element on the microstructure and tensile properties of Ti6Al4V  

Microsoft Academic Search

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\\u000a which produces unique, fine microstructures. Specimens of the alloy were heated to 870°C, transformed at temperatures between\\u000a 540°C and 700°C, and the microstructures were determined as a function of hydrogen content and transformation temperature.\\u000a Microstructures

William R. Kerr

1985-01-01

394

[Distribution of chemical elements in whole blood and plasma].  

PubMed

The distribution factor (Fd) of 35 elements of plasma and whole blood in 26 healthy men and women was detected by ICP-OES. Usilig this parameter the elements were subdivided in 3 pools. 9 of them have Fd higher than 1.5 ("elements of plasma"-Ag, Ca, Cu, In, Li, Na, Se, Si, Sr); 6 have lower than 0.5 ("elements of blood cells"-Fe, K, Mn, Ni, V, Zn), other 20-about 1 ("blood elements"). Fd of all elements depends on ionic radius. Elements of 2nd sub-groups of all groups of Mendeleev's periodic table ("heavy metals") depend on the similar law: "with growing of ionic radius the concentration of elements in plasma enhances". In alkaline metals Fd depends on the opposite law:" with growing of ionic radius of alkaline metal the quantity of elements in blood cells enhance". Dependence of Fd on the value of atomic mass in periods or in exterior electronic cloud (s-, p-, d-, f-) was not established. The table of distribution of all detected elements in whole blood in relation to 8 macroelements (Ca, Mg, K, Na, S, P, Fe, Zn,) is presented, as a basic diagnostic criteria in metal-ligand homeostasis disturbance. PMID:14564741

Barashkov, G K; Za?tseva, L I; Kondakhchan, M A; Konstantinova, E A

395

[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

396

Top Quark Mass Measurement in the t anti-t All Hadronic Channel using a Matrix Element Technique in p anti-p Collisions at s**91/2) = 1.96-TeV  

SciTech Connect

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

Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.; /Chicago U., EFI; Akimoto, T.; /Tsukuba U.; Alvarez Gonzalez, B.; /CSIC, Catalunya; Amerio, S.; /INFN, Padua; Amidei, Dante E.; /Michigan U.; Anastassov, A.; /Northwestern U.; Annovi, Alberto; /Frascati; Antos, J.; /Comenius U.; Apollinari, G.; /Fermilab; Apresyan, A.; /Purdue U. /Waseda U.

2008-11-01

397

Cross sections for the production of residual nuclides by low- and medium-energy protons from the target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au  

NASA Astrophysics Data System (ADS)

Cross sections for residual nuclide production by p-induced reactions were measured from thresholds up to 2.6 GeV using accelerators at CERN/Geneve, IPN/Orsay, KFA/Jülich, LANL/Los Alamos, LNS/Saclay, PSI/Villigen, TSL/Uppsala, LUC/Louvain La Neuve. The target elements C, N, O, Mg, Al, Si, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Nb, Ba and Au were investigated. Residual nuclides were measured by X- and ?-spectrometry and by Accelerator Mass Spectrometry (AMS). The measured cross sections were corrected for interfering secondary particles in experiments with primary proton energies above 200 MeV. Our consistent database covers presently ca 550 nuclear reactions and contains nearly 15000 individual cross sections of which about 10000 are reported here for the first time. They provide a basis for model calculations of the production of cosmogenic nuclides in extraterrestrial matter by solar and galactic cosmic ray protons. They are of importance for many other applications in which medium energy nuclear reactions have to be considered ranging from astrophysics over space and environmental sciences to accelerator technology and accelerator-based nuclear waste transmutation and energy amplification. The experimental data are compared with theoretical ones based on calculations using an INC/E model in form of the HETC/KFA2 code and on the hybrid model of preequilibrium reactions in form of the AREL code.>

Michel, R.; Bodemann, R.; Busemann, H.; Daunke, R.; Gloris, M.; Lange, H.-J.; Klug, B.; Krins, A.; Leya, I.; Lüpke, M.; Neumann, S.; Reinhardt, H.; Schnatz-Büttgen, M.; Herpers, U.; Schiekel, Th.; Sudbrock, F.; Holmqvist, B.; Condé, H.; Malmborg, P.; Suter, M.; Dittrich-Hannen, B.; Kubik, P.-W.; Synal, H.-A.; Filges, D.

1997-07-01

398

DISCOVERY OF THE ELEMENT 102  

Microsoft Academic Search

In Julu 1957. the discovery of element 102 was announced by a group of ; Swedish scientists. The new element was obtained by bringing particles of curium ; (element 96) into contact with carbon ions, accelerated in a cyclotron. The new ; element has the mass 253 and is extremely unstable. Its half-life is from 10 to ; 12 minutes,

Rodin

1957-01-01

399

The Last element in a New Periodic Table  

NASA Astrophysics Data System (ADS)

Among scientists there is no common opinion about possible number of the elements in the Periodic Table. The existing points of view lay within the limits from 120 up to 218 and more. However if to arrange the number of isotopes depending on the charge of a nuclei of atoms the broken curve in the form of the average parabola will turn out, in descending which branch the number of the isotopes sharply decreases, reaching units at all up to the end of the 7th period. After achievement of the maximum in the 6th period, the number of the isotopes sharply decreases. Hardly it is necessary to tell about prospective new 100 elements when are unsolved all of the problem up to N 119. As a result of the establishment of the top border of the Periodic Table there is a question about the location of the last element. From the views on the symmetry, it should be close to the 1st group. On the electronic configuration calculated for 218 elements, its place in the 5th group: 2, 8, 18, 32, 50, 32, 11, 2. Considering that fact, that in the 8th period has not 50 elements, we offer a following version to discuss: 2, 8, 18, 32, 36, 32, 18, 8, 1. (Progr. Phys., 2007, v.1, 38; v.2, 83; v.2, 104; 2008, v.3, 56).

Khazan, Albert

2008-10-01

400

V? Cluster Sequences Reduce the Frequency of Primary V?2 and V?14 Rearrangements  

PubMed Central

T cell receptor (TCR) ? variable region exons are assembled from numerous gene segments in a highly ordered and regulated manner. To elucidate mechanisms and identify cis-acting elements that control V? rearrangement, we generated an endogenous TCR? allele with only the V?2, V?4, and V?14 segments. We found that ?? T lineage cells containing this V?2-4-14 allele and a wild-type TCR? allele developed normally, but exhibited a significant increase in V?2+ and V?14+ cells. To quantify V? rearrangements on the V?2-4-14 allele, we generated ?? T cell hybridomas and analyzed TCR? rearrangements. Despite the deletion of almost all V? segments and 234 kb of V? cluster sequences, the V?2-4-14 allele exhibited only a slight decrease in V? rearrangement as compared to the wild-type TCR? allele. Thus, cis-acting control elements essential for directing V? rearrangement across large chromosomal distances are not located within the V? cluster. We also found a significant increase in the frequency of V? rearrangements involving V?2 and V?14, but not V?4, on the V?2-4-14 allele. Collectively, our data suggest that V? cluster sequences reduce the frequency of V?2 and V?14 rearrangements by competing with the productive coupling of accessible V?2 and V?14 segments with DJ?1 complexes.

Bassing, Craig H.; Whitlow, Scott; Mostoslovasky, Raul; Yang, Katherine; Ranganath, Sheila; Alt, Frederick W.

2009-01-01

401

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

402

Sequence-stratigraphic elements and geochemical variability within a {open_quotes}condensed section{close_quotes}: Eagle Ford Group, east-central Texas  

SciTech Connect

The Cenomanian-Turonian Eagle Ford Group, the likely source for the East Texas field, crops out along a broad belt in central and northeastern Texas. Detailed analysis of Eagle Ford outcrops in central Texas reveals considerable variability at several different scales. A lower section is interpreted to represent transgressive, in-part {open_quotes}condensed{close_quotes} deposits, whereas the overlying section is interpreted as a highstand deposit. This sequence-stratigraphic framework is suggested by stratigraphic and geochemical evidence. The lower portion of the measured Eagle Ford Group outcrops contains dark shales with a blocky character. These shales exhibit minor bioturbation and are well laminated. A few bentonites are evident in this portion of the section but are not as significant as in the overlying unit. Above this interval, the Eagle Ford changes character dramatically, exhibiting a series of interbedded carbonate flags and recessive shales and numerous bentonites. Several bentonite layers appear to be continuous regionally, and compositional analyses suggest that they may be useful in stratigraphic correlation. Detailed organic geochemical analyses clearly differentiate the upper and lower Eagle Ford. The shales in the lower transgressive unit are organically enriched, exhibit higher generation potentials, and are more oil prone than shales in the overlying regressive interval. Even within the oil-prone intervals, there is considerable variation in geochemical attributes. This work raises concerns about uncritically equating {open_quotes}condensed sections{close_quotes} with source rock potential.

Liro, L.M.; Dawson, W.C.; Katz, B.J. [Texaco EPTD, Houston, TX (United States)] [and others

1994-09-01

403

Observation of a martensitic structural distortion in V, Nb, and Ta.  

PubMed

Thermal-expansion measurements of the Group 5 elements V, Nb, and Ta reveal a structural distortion below 300 K. Data for single-crystalline Nb and Ta display anisotropic thermal expansion, martensitic in character, that is inconsistent with cubic crystal structures at low temperature. Published results on V show similar behavior. Interstitial impurities suppress the transition. PMID:21902404

Bollinger, R K; White, B D; Neumeier, J J; Sandim, H R Z; Suzuki, Y; dos Santos, C A M; Avci, R; Migliori, A; Betts, J B

2011-08-10

404

Role of vanadium (V) in the differentiation of C3H10t1/2 cells towards osteoblast lineage: a comparative analysis with other trace elements.  

PubMed

In recent time, vanadium compounds are being used as antidiabetic drug and in orthopedic implants. However, the exact role of this incorporated vanadium in improving the quality of bone structure and morphology is not known. The impact of vanadium ion was studied and compared to other trace metal ions with respect to the proliferation and osteoblast differentiation of C3H10t1/2 cells. Toxicity profile of these trace metal ions revealed a descending toxicity trend of Fe(2+) > Zn(2+) > Cu(2+) > Co(2+) > Mn(2+) > V(5+) > Cr(2+). The effect of vanadium and other trace metal ions on osteoblast differentiation was evaluated by culturing the cells for 10 days in osteoblastic medium supplemented with different trace ions at concentrations lower than their cytotoxic doses. The results indicated that vanadium has maximum impact on the induction of osteoblast differentiation by upregulating alkaline phosphatase activity and mineralization by up to 145 and 150 %, respectively (p?

Srivastava, Swati; Kumar, Narender; Thakur, Rajani Salunke; Roy, Partha

2013-01-18

405

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

406

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

407

Removal of elemental mercury (Hg(0)) by nanosized V{sub 2}O{sub 5}/TiO{sub 2} catalysts  

SciTech Connect

Novel reactive nanosized V{sub 2}O{sub 5}/TiO{sub 2} catalysts (aerogel, xerogel, and impregnated catalysts) for the removal of Hg{sup 0} and their synthesis methods have been introduced in this research. Aerogel catalyst has the highest surface area among the catalysts synthesized in this research and contained reactive monovanadates on its surfaces resulting in higher reactivity for the Hg{sup 0} removal than impregnated and selective catalytic reduction catalysts. XPS analyses on the surfaces of nanosized catalysts after the removal of Hg{sup 0} suggest that adsorbed Hg{sup 0} oxidatively transformed to Hg{sup O} by surface vanadates (mono- and poly vanadates), consistent with the Mars-Maessen mechanism. Early column breakthrough has been observed at temperatures above 300{sup o}C due mainly to the desorption of Hg{sup 0} from the catalyst surfaces. The decrease in Hg{sup 0} concentration and increase in catalyst content in a column reactor have increased the removal of Hg{sup 0}, indicating that the removal is a heterogeneous surface-limited reaction. At 400{sup o}C, the catalysts under air flow have shown a higher Hg{sup 0} removal because gas-phase oxygen from the flow could provide an oxygen-rich environment for producing more oxidized vanadate species on their surfaces. No significant difference in the Hg{sup 0} removal between different gas types (nitrogen and air) has been observed at 100{sup o}C. 27 refs., 5 figs.

Lee, W.; Bae, G.N. [Korea Advanced Institute of Science and Technology, Daejeon (Republic of Korea)

2009-03-01

408

Perceptual grouping and the interactions between visual cortical areas  

Microsoft Academic Search

Visual perception involves the grouping of individual elements into coherent patterns, such as object representations, that reduce the descriptive complexity of a visual scene. The computational and physiological bases of this perceptual remain poorly understood. We discuss recent fMRI evidence from our laboratory where we measured activity in a higher object processing area (LOC), and in primary visual cortex (V1)

Scott O. Murray; Paul R. Schrater; Daniel Kersten

2004-01-01

409

Structural, Spectroscopic, and Magnetochemical Characterization of the Trinuclear Vanadium(III) Carboxylates [V(3)O(O(2)CR)(6)L(3)](ClO(4)) (R = Various Groups; L = Pyridine, 4-Picoline, 3,5-Lutidine).  

PubMed

Synthetic procedures are described that allow access to the [V(3)O(O(2)CR)(6)L(3)](ClO(4)) (R = various groups; L = pyridine (py), 4-picoline (pic) or 3,5-lutidine (lut)) family of complexes. Treatment of VCl(3)(THF)(3) with NaO(2)CR (R = Me, Et) in RCO(2)H/py, pic/MeCN, or CH(2)Cl(2) solution followed by addition of NBu(n)(4)ClO(4) leads to isolation of [V(3)O(O(2)CR)(6)L(3)](ClO(4)) salts in 47-95% yields. A similar procedure for R = C(6)H(5), C(6)H(4)-p-OMe, C(6)H(3)-m-Me(2), and C(6)H(4)-p-Cl but omitting addition of NaO(2)CR provides the corresponding benzoate or substituted-benzoate derivatives in 24-56% yields. The X-ray structure of [V(3)O(O(2)CEt)(6)(pic)(3)](ClO(4)) (4) shows the anion to consist of a [V(3)O](7+) triangular fragment with a &mgr;(3)-O(2)(-) ion in the V(3) plane; each triangular edge is bridged by two EtCO(2)(-) groups in their familiar syn,syn modes, and there is a terminal pic group on each V(III) completing distorted octahedral geometries at the metal atoms. The cation has imposed C(2) symmetry (isosceles V(3) triangle), the C(2) axis passing through one V atom and the central &mgr;(3)-O atom, but has D(3)(h)() virtual symmetry (equilateral V(3) triangle). Complex 4 crystallizes in monoclinic space group C2/c with the following unit cell dimensions at -171 degrees C: a = 13.935(2) Å, b = 18.323(2) Å, c = 17.470(2) Å, beta = 95.55(1) degrees, V = 4439.7 Å(3), Z = 4. The structure was solved using 2657 unique reflections with F > 3sigma(F) and refined on F to conventional R (R(w)) values of 0.058 (0.066). Variable-temperature, solid-state magnetic susceptibility measurements were made on complex 1 in the 5.01-280 K region in a 1 kG magnetic field. The effective magnetic moment (&mgr;(eff)) per V(3) unit decreases gradually from 4.64 &mgr;(B) at 280 K to 1.76 &mgr;(B) at 5.01 K. The data were fit to the theoretical expression for an isosceles V(III)(3) complex, and the fitting parameters were J = -18.0(7) cm(-)(1), J' = -10.4(4) cm(-)(1), and g = 1.985, with TIP held constant at 600 x 10(-)(6) cm(3) mol(-)(1); J' refers to the unique exchange interaction within the isosceles triangle. The ground state of complex 1 thus has S = 0. PMID:11666666

Castro, Stephanie L.; Streib, William E.; Sun, Jui-Sui; Christou, George

1996-07-17

410

The 190Pt-186Os Decay System Applied to Dating Platinum-Group Element Mineralization in Layered Intrusions, Ophiolites and Detrital Deposits  

NASA Astrophysics Data System (ADS)

Discrete platinum-group minerals (PGM) occur as accessory phases in mafic-ultamafic intrusions and ophiolitic chromitites, as well as numerous detrital deposits globally. The 190Pt-186Os decay system, measured by laser ablation MC-ICPMS (LA-MC-ICPMS) provides a useful geochronometric tool for direct dating of PGM. Here we present two examples that verify the accuracy of the technique in geologically well constrained situations and demonstrate the potential for using the 190Pt-186Os PGM method to accurately date layered mafic intrusions, ophiolitic chromitites and detrital PGM deposits. Fifty PGM grains from three different horizons within the Bushveld complex yield a Pt-Os isochron age of 2012 ± 47 Ma (2?, MSWD = 1.19, 186Os/188Osi = 0.119818 ± 0.000006). This is consistent with the published U-Pb zircon age of 2054 Ma (Scoates and Friedman, 2008). The younger PGM isochron age is not likely to be a function of difference in blocking temperatures in the different systems. Pt-Os model ages are possible in high pt grains because initial 186Os/188Os can be well constrained. Using this approach we obtained Pt-Os model ages of 2113 ± 106 Ma and 2042 ± 102 Ma for a Bushveld Pt-Fe alloy and sperrylite respectively. Detrital PGM derived from the Meratus ophiolite, southeast Borneo yield a 190Pt-186Os isochron age of 202.5 Ma ± 8.3 Ma (2?, n = 260, MSWD = 0.90, 186Os/188Osi = 0.119830 ± 0.000003), consistent with radiometric and biostratigraphic age constraints (Wakita et al., 1998). We interpret this as the age of formation of the PGM grains in during chromitite genesis in the lower oceanic lithosphere. Our combined data demonstrate the utility of the LA-MC-ICPMS method as a tool for accurate Pt-Os dating of detrital PGM as well as their igneous parent bodies. We can constrain Pt/Os fractionation at the ablation site as being < 2.5%, while within-grain heterogeneity is ultimately one of the strongest controls on isochron and single-grain ages given the partial sampling represented by laser ablation. Scoates, J.S. and Friedman, R.M. 2008. Precise age of the platiniferous Merensky reef, Bushveld Complex, South Africa, by the U-Pb zircon chemical abrasion ID-TIMS technique; Economic Geology 103, p. 465-471. Wakita, K., Miyazaki, K., Zulkarnain, I., Sopaheluwakan, J. and Sanyoto, P. 1998. Tectonic implications of new age data for the Meratus complex of south Kalimantan, Indonesia; Island Arc 7, p. 202-222.

Coggon, J. A.; Nowell, G.; Pearson, G.; Oberthür, T.; Lorand, J.; Melcher, F.; Parman, S. W.

2010-12-01

411

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

412

Search for standard model Higgs boson production in association with a W boson using a matrix element technique at CDF in pp¯ collisions at s=1.96TeV  

NASA Astrophysics Data System (ADS)

This paper presents a search for standard model Higgs boson production in association with a W boson using events recorded by the CDF experiment in a data set corresponding to an integrated luminosity of 5.6fb-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 ?(pp¯?WH)×B(H?bb¯). The observed limits range from 3.5 to 37.6 relative to the standard model expectation for Higgs boson masses between mH=100GeV/c2 and mH=150GeV/c2. The 95% C.L. expected limit is estimated from the median of an ensemble of simulated experiments and varies between 2.9 and 32.7 relative to the production rate predicted by the standard model over the Higgs boson mass range studied.

Aaltonen, T.; Álvarez González, B.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bisello, D.; Bizjak, I.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Buzatu, A.; Calamba, A.; Calancha, C.; Camarda, S.; Campanelli, M.; Campbell, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Carron, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cavalli-Sforza, M.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Chlebana, F.; Cho, K.; Chokheli, D.; Chung, W. H.; Chung, Y. S.; Ciobanu, C. I.; Ciocci, M. A.; Clark, A.; Clarke, C.; Compostella, G.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Crescioli, F.; Cuevas, J.; Culbertson, R.; Dagenhart, D.; d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Dell'Orso, M.; Demortier, L.; Deninno, M.; Devoto, F.; d'Errico, M.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; D'Onofrio, M.; Donati, S.; Dong, P.; Dorigo, M.; Dorigo, T.; Ebina, K.; Elagin, A.; Eppig, A.; Erbacher, R.; Errede, S.; Ershaidat, N.; Eusebi, R.; Farrington, S.; Feindt, M.; Fernandez, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Frank, M. J.; Franklin, M.; Freeman, J. C.; Funakoshi, Y.; Furic, I.; Gallinaro, M.; Garcia, J. E.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Giannetti, P.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Giurgiu, G.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Goldschmidt, N.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Grinstein, S.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Halkiadakis, E.; Hamaguchi, A.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, D.; Hare, M.; Harr, R. F.; Hatakeyama, K.; Hays, C.; Heck, M.; Heinrich, J.; Herndon, M.; Hewamanage, S.; Hocker, A.; Hopkins, W.; Horn, D.; Hou, S.; Hughes, R. E.; Hurwitz, M.; Husemann, U.; Hussain, N.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Khotilovich, V.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. B.; Kim, S. H.; Kim, Y. K.; Kim, Y. J.; Kimura, N.; Kirby, M.; Klimenko, S.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Krop, D.; Kruse, M.; Krutelyov, V.; Kuhr, T.; Kurata, M.; Kwang, S.; Laasanen, A. T.; Lami, S.; Lammel, S.; Lancaster, M.; Lander, R. L.; Lannon, K.; Lath, A.; Latino, G.; LeCompte, T.; Lee, E.; Lee, H. S.; Lee, J. S.; Lee, S. W.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lin, C.-J.; Lindgren, M.; Lipeles, E.; Lister, A.; Litvintsev, D. O.; Liu, C.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maeshima, K.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Margaroli, F.; Marino, C.; Martínez, M.; Mastrandrea, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McFarland, K. S.; McIntyre, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Mondragon, M. N.; Moon, C. S.; Moore, R.; Morello, M. J.; Morlock, J.; Movilla Fernandez, P.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Neubauer, M. S.; Nielsen, J.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagan Griso, S.; Pagliarone, C.; Palencia, E.; Papadimitriou, V.; Paramonov, A. A.; Patrick, J.; Pauletta, G.; Paulini, M.; Paus, C.; Pellett, D. E.; Penzo, A.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Prokoshin, F.; Pranko, A.; Ptohos, F.; Punzi, G.; Rahaman, A.; Ramakrishnan, V.; Ranjan, N.; Redondo, I.; Renton, P.; Rescigno, M.; Riddick, T.; Rimondi, F.; Ristori, L.; Robson, A.; Rodrigo, T.; Rodriguez, T.; Rogers, E.; Rolli, S.; Roser, R.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Safonov, A.

2012-04-01

413

High-contrast process using a positive-tone resist with antistatic coating and high-energy (100-keV) e-beam lithography for fabricating diffractive optical elements (DOE) on quartz  

NASA Astrophysics Data System (ADS)

Diffractive optical elements (DOE) are becoming important as optical signal processing elements in increasingly diverse applications. These elements, fabricated on quartz, may be used as phase shift type masks or as embedded components that implement a transfer function within a processing network. A process is under development for the fabrication of a DOE implementing a Jervis error diffusion kernel for research in half tone image processing. Dry etching is performed after lithography and pattern transfer through a nickel mask. This results in etched areal features on the substrate. An optical diffraction medium is thus created. Lithographic patterning is done by e-beam lithography (EBL) to realize small features, but also offers the important advantage of a large depth of field which relaxes the problem of complex surface topology. The recent availability of high energy (100 KeV) lithography tools provides a capability for precision overlay, small feature resolution, and enhanced image contrast through a lower induced proximity effect. Patterning by EBL on insulating substrates is complicated by the necessity of providing a vehicle for the avoidance of charge buildup on the surface. In a previously presented paper a methodology was shown for the use of TQV-501 (Nitto Chemical) antistatic compound as a final spin on film for use with PMMA and SAL-601 (Shipley). In this current work, a process is described using EBL and a high performance positive resist working with a final film layer of antistatic TQV-501 on a nickel coated wafer. The process may then be reapplied to realize additional lithographic levels in registration, for multilevel DOE components. High energy (100 KeV) EBL is used to provide high quality pattern definition. The e-beam sensitive resist, ZEP-320-37 (Nagase Chemical) in dilution, together with a top film layer of TQV-501 serves as a bilevel resist system and is used for patterning the desired image before definition of the nickel mask through a wet etch. ZEP- 320-37 in 1:1 dilution with the native solvent is spin applied and softbaked for 2 hours at 120 degree(s)C, after which the antistatic film is spin applied and softbaked for 10 minutes at 70 degree(s)C. After exposure, the TQV film is removed within the development procedure itself. The image is developed in xylene followed by a thorough IPA rinse. The pattern is then transferred to the nickel film via a dilute HCl etch bath. Finally, magnetron RIE is performed on the substrate through the defined nickel mask, after which the nickel film is completely removed in HCl.

Poli, Louis C.; Kondek, Christine A.; Shoop, Barry L.; McLane, George F.

1995-06-01

414

Determination of Characteristics of Delayed Neutron Groups from Heavy Isotope Photofission at Esub( Gamma Max) = 17,5 MeV.  

National Technical Information Service (NTIS)

The time-dependent distributions of delayed neutrons from photofission of U exp 235 ; U exp 238 , Pu exp 239 , Th exp 232 , Np exp 237 isotopes were measured of the M-30 microtron. The relative intensities and half-lifes of the delayed neutron groups from...

V. M. Aleksandrov P. P. Ganich A. S. Krivokhatskij V. I. Lomonosov A. M. Parlag

1976-01-01

415

Extent of Antigenic Diversity in the V3 Region of the Surface Glycoprotein, gp120, of Human Immunodeficiency Virus Type 1 Group M and Consequences for Serotyping  

Microsoft Academic Search

Human immunodeficiency virus type 1 (HIV-1) may be studied by molecular or immunological approaches. Most analyses have been performed by genetic comparison of isolates and have led to the definition of clades or subtypes within the major (M) group of HIV-1. Five subtypes (A to E) were initially identified by comparison of genomic sequences. Four new subtypes (F to I)

JEAN-CHRISTOPHE PLANTIER; SOPHIE LE POGAM; FRANCIS POISSON; LAURENCE BUZELAY; BERNARD LEJEUNE; FRANCIS BARIN

1998-01-01

416

KAOS/LIB-V: A library of nuclear response functions generated by KAOS-V code from ENDF/B-V and other data files  

SciTech Connect

KAOS/LIB-V: A library of processed nuclear responses for neutronics analyses of nuclear systems has been generated. The library was prepared using the KAOS-V code and nuclear data from ENDF/B-V. The library includes kerma (kinetic energy released in materials) factors and other nuclear response functions for all materials presently of interest in fusion and fission applications for 43 nonfissionable and 15 fissionable isotopes and elements. The nuclear response functions include gas production and tritium-breeding functions, and all important reaction cross sections. KAOS/LIB-V employs the VITAMIN-E weighting function and energy group structure of 174 neutron groups. Auxiliary nuclear data bases, e.g., the Japanese evaluated nuclear data library JENDL-2 were used as a source of isotopic cross sections when these data are not provided in ENDF/B-V files for a natural element. These are needed mainly to estimate average quantities such as effective Q-values for the natural element. This analysis of local energy deposition was instrumental in detecting and understanding energy balance deficiencies and other problems in the ENDF/B-V data. Pertinent information about the library and a graphical display of the main nuclear response functions for all materials in the library are given. 35 refs.

Farawila, Y.; Gohar, Y.; Maynard, C.

1989-04-01

417

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