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Group-V elemental monolayers: the case of antimonene  

E-print Network

Group-V elemental monolayers including phosphorene are emerging as promising 2D materials with semiconducting electronic properties. Here, we present the results of first principles calculations on stability, mechanical and electronic properties of 2D antimony, antimonene. Our calculations show that {\\alpha} and \\b{eta} allotropes of antimonene are stable and semiconducting. The {\\alpha}-Sb has a distorted atomic structure with two atomic sub-layers and \\b{eta}-Sb has a buckled hexagonal lattice. The calculated Raman spectra and STM images have distinct features identifying in-plane and out-of-plane vibrating modes in both allotropes. The \\b{eta}-Sb has nearly isotropic mechanical properties while {\\alpha}-Sb shows strongly anisotropic characteristics. An indirect-direct band gap transition is expected with moderate tensile strains applied to antimonene monolayers. Since the mechanical exfoliation (scotch tape) approach will be difficult to fabricate antimonene due to large binding energy of bilayers, the sta...

Wang, Gaoxue; Karna, Shashi P



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

NASA Astrophysics Data System (ADS)

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

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



Incorporation and activation of group V elements in MOVPE-grown Cd xHg 1- xTe  

NASA Astrophysics Data System (ADS)

Reproducible acceptor doping has been achieved in MOVPE-grown layers of Cd xHg 1- xTe using Group V elements. Dopant element concentrations have been controlled over the range 5×10 15-8×10 17 cm -13 for As. Agreement has been obtained between these levels and Hall measurements made on annealed samples, at least for concentrations above 5×10 16 cm -3. At lower levels residual impurities may exert a significant influence on the electrical behaviour of layers. In order to achieve dopant activation it has been found necessary to establish "metal-rich" conditions during the CdTe growth cycle. High temperature anneals to activate the dopant are thus avoided which permits the growth of heterolayers with sharpe interfaces, both in terms of x and dopant concentration.

Capper, P.; Maxey, C. D.; Whiffin, P. A. C.; Easton, B. C.



Left 3Engel elements in groups  

Microsoft Academic Search

In this paper we study left 3-Engel elements in groups. In particular, we prove that for any prime p and any left 3-Engel element x of finite p-power order in a group G, xp is in the Baer radical of G. Also it is proved that ?x,y? is nilpotent of class at most 4 for every two left 3-Engel elements

Alireza Abdollahi



Left 3Engel elements in groups  

Microsoft Academic Search

In this paper we study left 3-Engel elements in groups. In particular, we prove that for any prime $p$ and any left 3-Engel element $x$ of finite $p$-power order in a group $G$, $x^p$ is in the Baer radical of $G$. Also it is proved that $$ is nilpotent of class 4 for every two left 3-Engel elements in a

Alireza Abdollahi



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.



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

SciTech Connect

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

Gates, Jacklyn M.



Sortable elements in infinite Coxeter groups  

E-print Network

In a series of previous papers, we studied sortable elements in finite Coxeter groups, and the related Cambrian fans, and applied these constructions to cluster algebras of finite type and to the noncrossing partitions associated to Artin groups of finite type. In this paper, as the first step towards expanding these applications beyond finite type, we study sortable elements in a general Coxeter group W. We supply uniform arguments which transform all previous finite-type proofs into uniform proofs (rather than type by type proofs), generalize many of the finite-type results and prove new and more refined results. The key tools in our proofs include a skew-symmetric form related to (a generalization of) the Euler form of quiver theory and the projection \\pidown^c mapping each element of W to the unique maximal c-sortable element below it in the weak order. The fibers of \\pidown^c essentially define the c-Cambrian fan. The most fundamental results are, first, a precise statement of how sortable elements trans...

Reading, Nathan



V-V compact group of galaxies  

NASA Technical Reports Server (NTRS)

A search for X-ray emission from five compact groups of galaxies with the Einstein Observatory revealed detections from three groups. Soft, extended X-ray emission was observed in Stephan's Quintet which is most likely caused by hot intracluster gas. This provides evidence for dynamical interaction among the group galaxies. X-ray emission from the group Arp 330 may also originate in hot intracluster gas. Stephan's Quintet and Arp 330 have the largest velocity dispersions among the groups studied suggesting a correlation between high velocity and the release (or properties) of hot gas. X-ray emission from Arp 318 may originate in its member galaxies.

Bahcall, N.



Stable kagome lattices from group IV elements  

NASA Astrophysics Data System (ADS)

A thorough investigation of three-dimensional kagome lattices of group IV elements is performed with first-principles calculations. The investigated kagome lattices of silicon and germanium are found to be of similar stability as the recently proposed carbon kagome lattice. Carbon and silicon kagome lattices are both direct-gap semiconductors but they have qualitatively different electronic band structures. While direct optical transitions between the valence and conduction bands are allowed in the carbon case, no such transitions can be observed for silicon. The kagome lattice of germanium exhibits semimetallic behavior but can be transformed into a semiconductor after compression.

Leenaerts, O.; Schoeters, B.; Partoens, B.



Distributed process groups in the V Kernel  

Microsoft Academic Search

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

David R. Cheriton; Willy Zwaenepoel




E-print Network

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

Sudoplatov, Sergey Vladimirovich


Potential Mobilization of Platinum-Group Elements by  

E-print Network

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


©2007 Society of Economic Geologists, Inc. Economic Geology, v. 102, pp. 1079–1089 Effects of Mother Lode-Type Gold Mineralization on 187 Os / 188 Os and Platinum Group Element Concentrations in Peridotite: Alleghany District, California  

E-print Network

Osmium isotope compositions and concentrations of Re, platinum group elements (PGE), and Au were determined for host peridotites (serpentinites and harzburgites) and hydrothermally altered ultramafic wall rocks associated with Mother Lode-type hydrothermal gold-quartz vein mineralization in the

Richard J. Walker; John Karl Böhlke; William F. Mcdonough; Ji Li


How to efficiently select an arbitrary Clifford group element  

E-print Network

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

Robert Koenig; John A. Smolin



The Heavy Element Abundance in Groups of Galaxies  

NASA Technical Reports Server (NTRS)

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

David, Laurence



Parallel and Serial Grouping of Image Elements in Visual Perception  

ERIC Educational Resources Information Center

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

Houtkamp, Roos; Roelfsema, Pieter R.



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

E-print Network

An experimental study of mass transfer of platinum-group elements, gold, nickel and copper by the vapor. © 2006 Elsevier B.V. All rights reserved. Keywords: Platinum-group elements; Gold; Nickel; Copper of the system, and the sulfur fugacity ( f S2). In experiments containing only Au-alloy and monosulfide solid

Long, Bernard


Photochemistry and charge transfer chemistry of the platinum group elements  

SciTech Connect

Significant progress has been made on the photochemistry and photophysics of platinum group element dithiolate complexes. The specific systems under investigation are square planar complexes of Pt(II) containing a dithiolate chelate and two other donor groups to complete the coordination sphere. The donor groups may be amines, imines, phosphines, phosphites or olefins, and they can be either monodentate or joined together as part of a chelate ring.

Eisenberg, R.



Platinum group elements in the environment and their health risk  

Microsoft Academic Search

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

Khaiwal Ravindra; László Bencs; René Van Grieken



Rhodium and other platinum-group elements in carbonaceous chondrites  

Microsoft Academic Search

Five carbonaceous chondrites (including the CI chondrites Orgueil and Ivuna) were analyzed by spark source mass spectrometry (SSMS) for the platinum-group elements Ru, Rh, Os, Ir, Pt, as well as W, Re, An, Th, and U. Conventional photoplate detection and a recently developed multi-ion counting system were used for ion detection.Results obtained for CI chondrites agree with compiled values within

K. P. Jochum



Homoleptic low-valent polyazides of group 14 elements.  


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

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



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

NASA Astrophysics Data System (ADS)

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

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



Chemical evolution of heavy elements in the Local Group  

NASA Astrophysics Data System (ADS)

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

Gabriele, Cescutti; Francesca, Matteucci



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

NASA Astrophysics Data System (ADS)

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

Brydges, David C.; Slade, Gordon



Platinum-group element abundance patterns in different mantle environments  

SciTech Connect

Mantle-derived xenoliths from the Cameroon Line and northern Tanzania display differences in their platinum-group element (PGE) abundance patterns. The Cameroon Line lherzolites have uniform PGE patterns indicating a homogeneous upper mantle over several hundreds of kilometers, with approximately chondritic PGE ratios. The PGE patterns of the Tanzanian peridotites are similar to the PGE systematics of ultramafic rocks from ophiolites. The differences can be explained if the northern Tanzanian lithosphere developed in a fluid-rich suprasubduction zone environment, whereas the Cameroon Line lithosphere only experienced melt extraction from anhydrous periodotites. 32 refs., 2 figs., 1 tab.

Rehkaemper, M.; Halliday, A.N.; Barfod, D. [Univ. of Michigan, Ann Arbor, MI (United States)] [Univ. of Michigan, Ann Arbor, MI (United States); Fitton, J.G.; Dawson, J.B. [Univ. of Edinburgh (United Kingdom)] [Univ. of Edinburgh (United Kingdom)



Cyclic silylated onium ions of group 15 elements.  


Five- and six-membered cyclic silylated onium ions of group 15 elements I were synthesized by intramolecular cyclization of transient silylium ions II. Silylium ions II were prepared by the hydride transfer reaction from silanes III using trityl cation as hydride acceptor. It was found that smaller ring systems could not be obtained by this approach. In these cases tritylphosphonium ions IV were isolated instead. Cations I and IV were isolated in the form of their tetrakispentafluorphenyl borates and characterized by multinuclear NMR spectroscopy and, in two cases, by X-ray diffraction analysis. Cyclic onium ions I showed no reactivity similar to that of isoelectronic intramolecular borane/phosphane frustrated Lewis pairs (FLPs). The results of DFT computations at the M05-2X level suggest that the strength of the newly formed Si-E linkage is the major reason for inertness of I[B(C6F5)4] versus molecular hydrogen. PMID:25664605

Reißmann, Matti; Schäfer, André; Panisch, Robin; Schmidtmann, Marc; Bolte, Michael; Müller, Thomas



Design of neutral Lewis superacids of group 13 elements.  


A general approach toward superstrong neutral Lewis acids, featuring both the pyramidalization of acceptor molecules and the introduction of electron-withdrawing substituents, is proposed and examined theoretically. Complexes of group 13 element derivatives with ammonia at the B3LYP and MP2 levels of theory with def2-TZVPP basis set are considered as examples. Pyramidalization of the acceptor molecule significantly increases its Lewis acidity (by 50-60 kJ mol(-1) for aluminum and gallium compounds and by 120-130 kJ mol(-1) for boron compounds). An additional increase of the complex stability of 55-75 kJ mol(-1) may be achieved by fluorination. The combined increase of the bond dissociation energy amounts to 110-190 kJ mol(-1), which is equivalent to 19-33 orders of magnitude in Lewis acidity. PMID:22168307

Mück, Leonie Anna; Timoshkin, Alexey Y; Frenking, Gernot



Doping of indium phosphide with group IV elements  

SciTech Connect

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

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



Bactericidal properties of group IIA and group V phospholipases A2  

Microsoft Academic Search

Group V phospholipase A2 (PLA2) is a recently characterized 14-kDa secretory PLA2 of mammalian heart and macrophage-derived cells. Group IIA PLA2, which is structurally close to group V PLA2, has been shown to kill Gram-positive bacteria in vitro and to prevent symptoms of Gram-positive infection in vivo. We studied the antibacterial properties of fully active recombinant rat group IIA and

J. O. Grönroos; Veli J. O. Laine; Marcel J. W. Janssen; Maarten R. Egmond; Timo J. Nevalainen



Analysis of Single and Group of Piles Subjected to Lateral Load Using Finite Element Method  

Microsoft Academic Search

Load carrying capacity and load deformation behaviour of a single pile and group of piles subjected to lateral load is obtained using nonlinear finite element method of analysis. In finite element analysis the soil is modeled using eight noded brick elements, pile is modeled using two noded frame elements and pile cap is modeled using plate bending elements. A hypoelasticity

K. J. Sharma


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)



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

E-print Network

I. ASCRC General Education Form Group Group V: Literary and Artistic Studies Dept of artists, artistic approaches, and historical periods. 2. Students learn to develop opinions about works artists, artistic approaches, and historical periods. V. Student Learning Goals: Briefly explain how

Vonessen, Nikolaus


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



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.



Bioaccessibility of platinum group elements in automotive catalytic converter particulates.  


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

Turner, Andrew; Price, Simon



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


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

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



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

E-print Network

We redetermine the abundances of all iron group nuclei in the Sun, based on neutral and singly-ionised lines of Sc, Ti, V, Mn, Fe, Co and Ni in the solar spectrum. We employ a realistic 3D hydrodynamic model solar atmosphere, corrections for departures from local thermodynamic equilibrium (NLTE), stringent line selection procedures and high quality observational data. We have scoured the literature for the best quality oscillator strengths, hyperfine constants and isotopic separations available for our chosen lines. We find $\\log \\epsilon_\\mathrm{Sc}=3.16\\pm0.04$, $\\log \\epsilon_\\mathrm{Ti}=4.90\\pm0.04$, $\\log \\epsilon_\\mathrm{V}=3.89\\pm0.08$, $\\log \\epsilon_\\mathrm{Cr}=5.62\\pm0.04$, $\\log \\epsilon_\\mathrm{Mn}=5.42\\pm0.04$, $\\log \\epsilon_\\mathrm{Fe}=7.47\\pm0.04$, $\\log \\epsilon_\\mathrm{Co}=4.93\\pm0.05$ and $\\log \\epsilon_\\mathrm{Ni}=6.20\\pm0.04$. Our uncertainties factor in both statistical and systematic errors (the latter estimated for possible errors in the model atmospheres and NLTE line formation). The ...

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



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

NASA Astrophysics Data System (ADS)

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

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




E-print Network



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

E-print Network

I. ASCRC General Education Form Group Group V Literary and Artistic Studies Dept/Program Applied the significance of works within the artistic traditions associated with various poetic forms, from sonnet to haiku of artistic representation; they also establish a framework and context for analysis of the structure

Vonessen, Nikolaus



E-print Network




E-print Network

5 5 4 4 3 3 2 2 1 1 D D C C B B A A CRICKET V2.0 NETWORKS AND MOBILE SYSTEMS GROUP CSAIL@MIT LEAD DESIGNER: NISSANKA B. PRIYANTHA 6310-0335-01 A MTS450CA CRICKET RS232 Crossbow Technology 41 Daggett Drive


I. ASCRC General Education Form Group V: Literary & Artistic Studies  

E-print Network

I. ASCRC General Education Form Group V: Literary & Artistic Studies Dept/Program Drama:// Courses cover a number of works in one or more of the various forms of artistic with respect to structure and significance within literary and artistic traditions, including emergent

Vonessen, Nikolaus


Finite groups with a certain number of elements pairwise generating a non-nilpotent subgroup  

Microsoft Academic Search

Let $n>0$ be an integer and $\\\\mathcal{X}$ be a class of groups. We say that a group $G$ satisfies the condition $(\\\\mathcal{X},n)$ whenever in every subset with $n+1$ elements of $G$ there exist distinct elements $x,y$ such that $$ is in $\\\\mathcal{X}$. Let $\\\\mathcal{N}$ and $ \\\\mathcal{A}$ be the classes of nilpotent groups and abelian groups, respectively. Here we prove

Alireza Abdollahi; Aliakbar Mohammadi Hassanabadi



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


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

Malea, Paraskevi; Chatziapostolou, Anastasia; Kevrekidis, Theodoros



Current Light Elements of the ? Scuti Star V393 Carinae  

NASA Astrophysics Data System (ADS)

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

Axelsen, R. A.



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.



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

E-print Network

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


3Generator Groups whose Elements Commute with Their Endomorphic Images Are Abelian  

Microsoft Academic Search

A group in which every element commutes with its endomorphic images is called an $E$-group. Our main result is that all 3-generator $E$-groups are abelian. It follows that the minimal number of generators of a finitely generated non-abelian $E$-group is four.

A. Abdollahi; A. Faghihi; A. Mohammadi Hassanabadi



Powers of Coxeter elements in infinite groups are reduced  

E-print Network

Let W be an infinite irreducible Coxeter group with (s_1, ..., s_n) the simple generators. We give a simple proof that the word s_1 s_2 ... s_n s_1 s_2 >... s_n ... s_1 s_2 ... s_n is reduced for any number of repetitions of s_1 s_2 >... s_n. This result was proved for simply-laced, crystallographic groups by Kleiner and Pelley using methods from the theory of quiver representations. Our proof only using basic facts about Coxeter groups and the geometry of root systems.

Speyer, David E



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

USGS Publications Warehouse

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

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



Method of fabricating vertically aligned group III-V nanowires  


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

Wang, George T; Li, Qiming



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

E-print Network

I. ASCRC General Education Form Group V Literary & Artistic Studies Dept/Program Art Course # UG:// Discussion of artists, artworks, critics and theories from the 1960's to the present. Introduction to major:// Students will view and critique works from major artists and art movements as well

Vonessen, Nikolaus


The Relationship Between Innovativeness and Selected Elements of Group Structure.  

ERIC Educational Resources Information Center

This study was an attempt to build upon the prior work in the area of the diffusion of innovations and innovativeness. Broadly stated, the study attempted to answer the question: What is the relationship between selected characteristics of intact groups and their innovativeness? The sample consisted of six elementary schools in Massachusetts which…

Crandall, David P.


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

NASA Astrophysics Data System (ADS)

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

Tantrabandit, Manop



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

NASA Technical Reports Server (NTRS)

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

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



Good product expansions for tame elements of reductive p-adic groups  

Microsoft Academic Search

We show that, under fairly general conditions, many elements of a p-adic group can be well approximated by a product whose factors have properties that are helpful in performing explicit character computations.

Jeffrey D. Adler; Loren Spice



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



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

E-print Network

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

Demouchy, Sylvie


Energy spectra of elemental groups of cosmic rays: Update on the KASCADE unfolding analysis  

NASA Astrophysics Data System (ADS)

The KASCADE experiment measures extensive air showers induced by cosmic rays in the energy range around the so-called knee. The data of KASCADE have been used in a composition analysis showing the knee at 3-5 PeV to be caused by a steepening in the light-element spectra [T. Antoni et al., (KASCADE Coll.), Astropart. Phys. 24 (2005) 1-25]. Since the applied unfolding analysis depends crucially on simulations of air showers, different high-energy hadronic interaction models (QGSJet and SIBYLL) were used. The results have shown a strong dependence of the relative abundance of the individual mass groups on the underlying model. In this update of the analysis we apply the unfolding method with a different low energy interaction model (FLUKA instead of GHEISHA) in the simulations. While the resulting individual mass group spectra do not change significantly, the overall description of the measured data improves by using the FLUKA model. In addition data in a larger range of zenith angle are analysed. The new results are completely consistent, i.e. there is no hint to any severe problem in applying the unfolding analysis method to KASCADE data.

Apel, W. D.; Arteaga, J. C.; Badea, A. F.; Bekk, K.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Brüggemann, M.; Buchholz, P.; Cossavella, F.; Daumiller, K.; de Souza, V.; Doll, P.; Engel, R.; Engler, J.; Finger, M.; Fuhrmann, D.; Gils, H. J.; Glasstetter, R.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Kickelbick, D.; Klages, H. O.; Kolotaev, Y.; ?uczak, P.; Mathes, H. J.; Mayer, H. J.; Milke, J.; Mitrica, B.; Nehls, S.; Oehlschläger, J.; Ostapchenko, S.; Over, S.; Petcu, M.; Pierog, T.; Rebel, H.; Roth, M.; Schatz, G.; Schieler, H.; Schröder, F.; Sima, O.; Stümpert, M.; Toma, G.; Ulrich, H.; van Buren, J.; Walkowiak, W.; Weindl, A.; Wochele, J.; Wommer, M.; Zabierowski, J.



A survey of the determination of the platinum group elements.  


The platinum-group metals (PGMs), Ru, Rh, Pd, Os, Ir and Pt, are widely used as catalysts in petroleum and chemical processes. They find wide applications in automotive exhaust-gas control converters and are of immense importance to the electronics industry. They are found in many items of jewellery and serve to an increasing extent as a form of investment. The PGMs are extracted in minute quantities from a limited number of ores, found mainly in S. Africa and the USSR. They are concentrated and separated from each other by elaborate chemical processes. Because of their great intrinsic value (Pt $650 per oz; Rh $1400 per oz), the recycling of the PGMs from literally hundreds of different forms of scrap is an essential factor in the overall management of the PGM economy. In this survey emphasis is placed on the need to tailor the analytical method according to (a) the environment in which the PGMs occur, (b) the individual PGM concentrations, and (c) the desired sensitivity and precision. The factors which determine the choice of chemical, physicochemical and/or instrumental approaches are discussed. They are further commented on in extensive presentations of dissolution and separation techniques and methods for the final measurement of individual PGMs. Appendices are provided which present the compositions and sources of the products most frequently encountered in PGM analysis, along with information on methods of decomposition, separations required, type of separation, and final determination. PMID:18964388

Kallmann, S



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

E-print Network

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

M. R. Kibler



Platinum group elements in the environment: emissions and exposure.  


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



On Silicon Group Elements Ejected by Supernovae Type Ia  

NASA Astrophysics Data System (ADS)

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

De, Soma; Timmes, F. X.; Brown, Edward F.; Calder, Alan C.; Townsley, Dean M.; Athanassiadou, Themis; Chamulak, David A.; Hawley, Wendy; Jack, Dennis



Quotients of group algebrae in the calculation of intermediate ligand field matrix elements  

Microsoft Academic Search

The structure of the classes of symmetry elements excluded during the subduction of the representations of SU(2) onto the finite group 0* is shown to quantitatively define the relationship of the coupling algebrae of these two groups. This relationship is formalized as a quotient algebra. This quotient algebra is realized as 3G-like symbols which exist whether or not the quotient

John C. Donini; Bryan R. Hollebone



CHANDRA observations of the NGC 1550 galaxy group -- implication for the temperature and entropy profiles of 1 keV galaxy groups  

E-print Network

We present a detailed \\chandra study of the galaxy group NGC 1550. For its temperature (1.37$\\pm$0.01 keV) and velocity dispersion ($\\sim$ 300 km s$^{-1}$), the NGC 1550 group is one of the most luminous known galaxy groups (L$_{\\rm bol}$ = 1.65$\\times10^{43}$ erg s$^{-1}$ within 200 kpc, or 0.2 \\rv). We find that within $\\sim 60$ kpc, where the gas cooling time is less than a Hubble time, the gas temperature decreases continuously toward the center, implying the existence of a cooling core. The temperature also declines beyond $\\sim$ 100 kpc (or 0.1 \\rv). There is a remarkable similarity of the temperature profile of NGC 1550 with those of two other 1 keV groups with accurate temperature determination. The temperature begins to decline at 0.07 - 0.1 \\rv, while in hot clusters the decline begins at or beyond 0.2 \\rv. Thus, there are at least some 1 keV groups that have significantly different temperature profiles from those of hot clusters, which may reflect the role of non-gravitational processes in ICM/IGM evolution. NGC 1550 has no isentropic core in its entropy profile, in contrast to the predictions of `entropy-floor' simulations. We compare the scaled entropy profiles of three 1 keV groups (including NGC 1550) and three 2 - 3 keV groups. The scaled entropy profiles of 1 keV groups show much larger scatter than those of hotter systems, which implies varied pre-heating levels. We also discuss the mass content of the NGC 1550 group and the abundance profile of heavy elements.

M. Sun; W. Forman; A. Vikhlinin; A. Hornstrup; C. Jones; S. S. Murray



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

E-print Network

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

Maurice Robert Kibler



Noninertial symmetry group with invariant Minkowski line element consistent with Heisenberg quantum commutation relations  

NASA Astrophysics Data System (ADS)

The maximal symmetry of a quantum system with Heisenberg commutation relations is given by the projective representations of the automorphism group of the Weyl-Heisenberg algebra. The automorphism group is the central extension of the inhomogeneous symplectic group with a conformal scaling that acts on extended phase space. We determine the subgroup that also leaves invariant a degenerate Minkowski orthogonal line element. This defines noninertial relativistic symmetry transformations that have the expected classical limit as c ? ?.

Low, Stephen G.



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)



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

E-print Network

?&) & . (&?54' (&?|i) ) "(&?7);, -. - V?&)t (&?))i -(P?R)i (P?$));4&?4)j:(3?9')'&:'($?6')t, 0'?V)' (0?0)'q. (Oj'R)I-gr?0)g (0?6) 6 eP5:W (B?04 . (~?&)i" (&?@). ( . (R?6) Ofs ~, HC t? RQ e I(0?O)y 84h. )) 8~'-:W'. R. 4 a &ef, e 8 5f'Ie I(@?0)) X& -:j e...'Ch infinite height, - Thez'e is a ema13. eat omdina1 4? o snob Chat I' ' ho :--. ?::: ? ?::--;. -': ?:--S~~+~maoh-4hab. +, ?. m-Q? ? -:? . ?:=gn~ %be:&~ Cha g 0) m E. 88 jj x g 81 1) n e81, gg&88W1), n peg 2) Xf'h - 1 ogists x 8 6 e z g &8 1- 8 ), z g...

Heatherly, Henry Edward



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


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



Spin-orbit effects in structural and electronic properties for the solid state of the group-14 elements from carbon to superheavy element 114  

NASA Astrophysics Data System (ADS)

Spin-orbit effects approximately scale like Z2 and therefore become very important in the bonding of the heavier p -group elements in the periodic table. Here we show by first-principles density-functional calculations that such effects substantially lower the cohesive energy for solid lead and Uuq (ununquadium, eka-lead, nuclear charge 114), by 2.5 eV/atom for the latter and causing a structural change from face-centered cubic at the scalar relativistic to hexagonal close packed at the spin-orbit coupled level of theory. This implies that unlike lead (cohesive energy Ecoh=2.02eV/atom ), Uuq is weakly bound (Ecoh=0.5eV/atom) , and even less so than solid mercury (Ecoh=0.7eV/atom) , underpinning the original hypothesis by Pitzer in 1975 [K. Pitzer, J. Chem. Phys. 63, 1033 (1975)10.1063/1.431398] that spin-orbit effects lead to chemical inertness of Uuq.

Hermann, Andreas; Furthmüller, Jürgen; Gäggeler, Heinz W.; Schwerdtfeger, Peter



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

Microsoft Academic Search

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.

M. Wachsmann; K. G. Heumann



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

SciTech Connect

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

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



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

Microsoft Academic Search

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

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



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



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.



This study tests the application of chalcophile elements such as nickel, copper and the platinum-group elements as indicators of nickel-sulphide prospectivity in komatiites from  

E-print Network

This study tests the application of chalcophile elements such as nickel, copper and the platinum-group elements as indicators of nickel-sulphide prospectivity in komatiites from terranes of the Karelian Craton in northern Finland and Norway. Major element abundances reflect volcanic processes associated


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

USGS Publications Warehouse

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

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



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



Platinum-group elements in porphyry copper deposits: a reconnaissance study  

Microsoft Academic Search

Summary Sulphide and flotation concentrates from 33 porphyry copper deposits have been investigated for platinum-group elements (PGE), Au, Cu and platinum-group minerals (PGM). The major sulphides in the samples studied are chalcopyrite and pyrite. Bornite is less frequent and molybdenite occurs in traces only. PGM (merenskyite, sperrylite and an unidentified Pd-Sb telluride) have been found as inclusions in chalcopyrite.

M. Tarkian; B. Stribrny



Minimal Number of Generators and Minimum Order of a Non-Abelian Group whose Elements Commute with Their Endomorphic Images  

Microsoft Academic Search

A group in which every element commutes with its endomorphic images is called an $E$-group. If $p$ is a prime number, a $p$-group $G$ which is an $E$-group is called a $pE$-group. Every abelian group is obviously an $E$-group. We prove that every 2-generator $E$-group is abelian and that all 3-generator $E$-groups are nilpotent of class at most 2. It

Alireza Abdollahi; A. Faghihi; A. Mohammadi Hassanabadi



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



Clinical and Allergological Biomonitoring of Occupational Hypersensitivity to Platinum Group Elements  

Microsoft Academic Search

Platinum (Pt), palladium (Pd), rhodium (Rh) and iridium (Ir), the platinum group elements (PGEs), have been reported to induce hypersensitive reactions. The purpose of this research was to assess: (i) the PGEs level in indoor air and in biological samples (blood, urine and hair) of workers involved in the assembly of catalysers and recycling metals; (ii) the prevalence and the

A. Cristaudo; M. Picardo; F. Petrucci; G. Forte; N. Violante; O. Senofonte; A. Alimonti; F. Sera



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



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)



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

E-print Network

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



EPA Science Inventory

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


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

Microsoft Academic Search

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

Ofelia Morton; Harald Puchelt; Elizabeth Hernández; Elena Lounejeva



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

Microsoft Academic Search

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

László Bencs; Khaiwal Ravindra; René Van Grieken



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

E-print Network

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

Paris-Sud XI, Université de


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

Code of Federal Regulations, 2014 CFR

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



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

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Element V-What does âno strike/lockout or layoffâ Registered Nurses? § 655.1115 Element V—What does “no strike/lockout or layoff” mean? (a) The fifth attestation element requires that the facility...



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

Code of Federal Regulations, 2011 CFR

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



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

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Element V-What does âno strike/lockout or layoffâ Registered Nurses? § 655.1115 Element V—What does “no strike/lockout or layoff” mean? (a) The fifth attestation element requires that the facility...



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

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Element V-What does âno strike/lockout or layoffâ Registered Nurses? § 655.1115 Element V—What does “no strike/lockout or layoff” mean? (a) The fifth attestation element requires that the facility...



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

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Element V-What does âno strike/lockout or layoffâ Registered Nurses? § 655.1115 Element V—What does “no strike/lockout or layoff” mean? (a) The fifth attestation element requires that the facility...



Improved zinc oxide surge arresters using high voltage gradient 300 V\\/mm, 400 V\\/mm ZnO elements  

Microsoft Academic Search

Zinc oxide surge arresters using zinc oxide (ZnO) elements have been widely used for insulation coordination in the world's power systems. These ZnO elements have basically reference voltage of about 200 V\\/mm. Recently, new ZnO elements having about 1.5, 2 times high voltage gradient zinc oxide element have been developed. This paper describes applications of high voltage gradient 300 V\\/mm

Shingo Shirakawa; Seiichi Yamada; Shigeru Tanaka; Iwao Ejiri; Satoshi Watahiki; Shinichi Kondo



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. PMID:22511016

Solbrig, Harold R; Chute, Christopher G



Toward Universality in Similarity Renormalization Group Evolved Few-body Potential Matrix Elements  

E-print Network

We first examine how T-matrix equivalence drives the flow of similarity renormalization group (SRG) evolved potential matrix elements to a universal form, with the ultimate goal of gaining insight into universality for three-nucleon forces. In agreement with observations made previously for Lee-Suzuki transformations, regions of universal potential matrix elements are restricted to where half-on-shell T-matrix equivalence holds, but the potentials must also reproduce binding energies. We find universality in local energy regions, reflecting a local decoupling by the SRG. To continue the study in the 3-body sector, we create a simple 1-D spinless boson "theoretical laboratory" for a dramatic improvement in computational efficiency. We introduce a basis-transformation, harmonic oscillator (HO) basis, which is used for current many-body calculations and discuss the imposed truncations. When SRG evolving in a HO-basis, we show that the evolved matrix elements, once transformed back into momentum-representation, d...

Dainton, Brian



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

NASA Technical Reports Server (NTRS)

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

Buckley, D. H.



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

NASA Technical Reports Server (NTRS)

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

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



Dynnikov coordinates on virtual braid groups V. Bardakova  

E-print Network

the virtual pure braid group and is denoted by VPn. Generators and relations for VPn are described in [1]. It is easy to see that VBn is a semidirect product: VBn = VPn S n. 2. Coordinates on braid groups In [2, Ch


Trithorax- and Polycomb-Group Response Elements within an Ultrabithorax Transcription Maintenance Unit Consist of Closely Situated but Separable Sequences  

Microsoft Academic Search

In Drosophila, two classes of genes, the trithorax group and the Polycomb group, are required in concert to maintain gene expression by regulating chromatin structure. We have identified Trithorax protein (TRX) binding elements within the bithorax complex and have found that within the bxd\\/pbx regulatory region these elements are functionally relevant for normal expression patterns in embryos and confer TRX




Cytogenetic mapping of the Muller F element genes in Drosophila willistoni group.  


Comparative genomics in Drosophila began in 1940, when Muller stated that the ancestral haploid karyotype of this genus is constituted by five acrocentric chromosomes and one dot chromosome, named A to F elements. In some species of the willistoni group such as Drosophila willistoni and D. insularis, the F element, instead of a dot chromosome, has been incorporated into the E element, forming chromosome III (E + F fusion). The aim of this study was to investigate the scope of the E + F fusion in the willistoni group, evaluating six other species. Fluorescent in situ hybridization was used to locate two genes of the F element previously studied-cubitus interruptus (ci) and eyeless (ey)-in species of the willistoni and bocainensis subgroups. Moreover, polytene chromosome photomaps corresponding to the F element (basal portion of chromosome III) were constructed for each species studied. In D. willistoni, D. paulistorum and D. equinoxialis, the ci gene was located in subSectction 78B and the ey gene in 78C. In D. tropicalis, ci was located in subSection 76B and ey in 76C. In species of the bocainensis subgroup, ci and ey were localized, respectively, at subsections 76B and 76C in D. nebulosa and D. capricorni, and 76A and 76C in D. fumipennis. Despite the differences in the subsection numbers, all species showed the same position for ci and ey. The results confirm the synteny of E + F fusion in willistoni and bocainensis subgroups, and allow estimating the occurrence of this event at 15 Mya, at least. PMID:25134938

Pita, Sebastián; Panzera, Yanina; Lúcia da Silva Valente, Vera; de Melo, Zilpa das Graças Silva; Garcia, Carolina; Garcia, Ana Cristina Lauer; Montes, Martín Alejandro; Rohde, Claudia



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


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)



Universality in similarity renormalization group evolved potential matrix elements and T-matrix equivalence  

NASA Astrophysics Data System (ADS)

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

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



Toward Universality in Similarity Renormalization Group Evolved Few-body Potential Matrix Elements  

E-print Network

We first examine how T-matrix equivalence drives the flow of similarity renormalization group (SRG) evolved potential matrix elements to a universal form, with the ultimate goal of gaining insight into universality for three-nucleon forces. In agreement with observations made previously for Lee-Suzuki transformations, regions of universal potential matrix elements are restricted to where half-on-shell T-matrix equivalence holds, but the potentials must also reproduce binding energies. We find universality in local energy regions, reflecting a local decoupling by the SRG. To continue the study in the 3-body sector, we create a simple 1-D spinless boson "theoretical laboratory" for a dramatic improvement in computational efficiency. We introduce a basis-transformation, harmonic oscillator (HO) basis, which is used for current many-body calculations and discuss the imposed truncations. When SRG evolving in a HO-basis, we show that the evolved matrix elements, once transformed back into momentum-representation, differ from those when evolving with momentum representation. This is because the generator in each basis is not exactly the same due to the truncation, which creates evolution artifacts in the 3-body potential matrix elements. In the 2- body sector, this can be avoided by increasing the basis size, but it remains unclear whether this is possible in the 3-body sector, as truncation errors in the 3-body sector are more difficult to avoid, and the computational power required is greatly increased for three-body evolution.

Brian Dainton



Minimal Number of Generators and Minimum Order of a Non-Abelian Group Whose Elements Commute with Their Endomorphic Images  

Microsoft Academic Search

A group in which every element commutes with its endomorphic images is called\\u000aan $E$-group. If $p$ is a prime number, a $p$-group $G$ which is an $E$-group\\u000ais called a $pE$-group. Every abelian group is obviously an $E$-group. We prove\\u000athat every 2-generator $E$-group is abelian and that all 3-generator $E$-groups\\u000aare nilpotent of class at most 2. It

Alireza Abdollahi; A. Faghihi; A. Mohammadi Hassanabadi



Domains 2 and 3 interact to form critical elements of the group II intron active site.  


Group II introns are self-splicing RNA molecules that also behave as mobile genetic elements. The secondary structure of group II intron RNAs is typically described as a series of six domains that project from a central wheel. Most structural and mechanistic analyses of the intron have focused on domains 1 and 5, which contain the residues essential for catalysis, and on domain 6, which contains the branch-point adenosine. Domains 2 and 3 (D2, D3) have been shown to make important contributions to intronic activity; however, information about their function is quite limited. To elucidate the role of D2 and D3 in group II ribozyme catalysis, we built a series of multi-piece ribozyme constructs based on the ai5gamma group II intron. These constructs are designed to shed light on the roles of D2 and D3 in some of the major reactions catalyzed by the intron: 5'-exon cleavage, branching, and substrate hydrolysis. Reactions with these constructs demonstrate that D3 stimulates the chemical rate constant of group II intron reactions, and that it behaves as a form of catalytic effector. However, D3 is unable to associate independently with the ribozyme core. Docking of D3 is mediated by a short duplex that is found at the base of D2. In addition to recruiting D3 into the core, the D2 stem directs the folding of the adjacent j(2/3) linker, which is among the most conserved elements in the group II intron active site. In turn, the D2 stem contributes to 5'-splice site docking and ribozyme conformational change. Nucleotide analog interference mapping suggests an interaction between the D2 stem and D3 that builds on the known theta-theta' interaction and extends it into D3. These results establish that D3 and the base of D2 are key elements of the group II intron core and they suggest a hierarchy for active-site assembly. PMID:12823961

Fedorova, Olga; Mitros, Therese; Pyle, Anna Marie



Determination of copper, scandium, molybdenum, tin, lead, and iron group elements in lunar surface materials  

NASA Technical Reports Server (NTRS)

Distribution regularities of copper, scandium, molybdenum, tin, lead, and iron group elements were investigated in basaltoid rocks of lunar and terrestrial origin. Samples of various regolith zones taken in the area of the Sea of Fertility were analyzed, along with samples of basic and ultrabasic rocks of the East African Rift for their content of the trace admixtures listed. Data obtained on the abundance of copper, scandium, molybdenum, tin, lead, cobalt, nickel, chromium, and vanadium in Luna 16 lunar surface material were compared with the abundance of these elements in samples of lunar rocks returned by Apollo 11, Apollo 12, and Apollo 14, with the exception of scandium; its content in the latter samples was considerably higher.

Pavlenko, L. I.; Simonova, L. V.; Karyakin, A. V.



The VIPER elements of trypanosomes constitute a novel group of tyrosine recombinase-enconding retrotransposons.  


VIPER was initially characterized as a 2326bp LTR-like retroelement associated to SIRE, a short interspersed repetitive element specific of Trypanosoma cruzi. It carried a single ORF that coded for a putative reverse transcriptase-RNAse H protein, suggesting that it could be a truncated copy of a longer retroelement. Herein we report the identification and characterization of a complete 4480bp long VIPER in the T. cruzi genome. The complete VIPER harbored three non-overlapped domains encoding for a GAG-like, a tyrosine recombinase and a reverse transcriptase-RNAse H proteins. VIPER elements were also found in the genomes of Trypanosoma brucei and Trypanosoma vivax, but not in Leishmania sp. On the basis of its reverse transcriptase phylogeny, VIPER was classified as an LTR retroelement. However, VIPER was structurally related to the tyrosine recombinase encoding retroelements, DIRS and Ngaro. Phylogenetic analysis showed that VIPER's tyrosine recombinase grouped with the transposases RCI1 of Escherichia coli and Ye24 and Ye72 of Haemophilus influenzae within a major branch of prokaryotic recombinases. Taken together, VIPER's structure, the nature of its tyrosine recombinase, the unique features of its reverse transcriptase catalytic consensus motif and the fact that it was found in Trypanosomes, an early branching eukaryote, suggest that VIPER may be the closest relative of the founder element of the tyrosine recombinase encoding retrotransposons known up to date. Our analysis revealed that tyrosine recombinase-encoding retroelements were originated as early in evolution as non-LTR retroelements and suggests that VIPER, Ngaro and DIRS elements may constitute a third group of retrotransposons, distinct from both LTR and non-LTR retroelements. PMID:16297462

Lorenzi, Hernan A; Robledo, German; Levin, Mariano J



Mobile elements and chromosomal evolution in the virilis group of Drosophila  

PubMed Central

Species of the virilis group of Drosophila differ by multiple inversions and chromosome fusions that probably accompanied, or led to, speciation. Drosophila virilis has the primitive karyotype for the group, and natural populations are exceptional in having no chromosomal polymorphisms. We report that the genomic locations of Penelope and Ulysses transposons are nonrandomly distributed in 12 strains of D. virilis. Furthermore, Penelope and Ulysses insertion sites in D. virilis show a statistically significant association with the breakpoints of inversions found in other species of the virilis group. Sixteen newly induced chromosomal rearrangements were isolated from the progeny of D. virilis hybrid dysgenic crosses, including 12 inversions, 2 translocations, and 2 deletions. Penelope and Ulysses were associated with the breakpoints of over half of these new rearrangements. Many rearrangement breakpoints also coincide with the chromosomal locations of Penelope and Ulysses insertions in the parental strains and with breakpoints of inversions previously established for other species of the group. Analysis of homologous sequences from D. virilis and Drosophila lummei indicated that Penelope insertion sites were closely, but not identically, located at the nucleotide sequence level. Overall, these results indicate that Penelope and Ulysses insert in a limited number of genomic locations and are consistent with the possibility that these elements play an important role in the evolution of the virilis species group. PMID:11016976

Evgen'ev, Michael B.; Zelentsova, Helena; Poluectova, Helena; Lyozin, George T.; Veleikodvorskaja, Vera; Pyatkov, K. I.; Zhivotovsky, Lev A.; Kidwell, Margaret G.



Extraction of group VIII elements with 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5  

Microsoft Academic Search

The extraction of group VIII elements with 1-phenyl-3-methyl-4-trifluoracetyl-pyrazolone-5 from aqueous solutions in chloroform\\u000a has been studied as a function of pH. Fe(III), Ni(II), Pd(II) and Rh(III) show partial extraction whereas Co(II) is extracted\\u000a quantitatively. The effect of citrate, cyanide, fluoride, iodide, thiosulphate and thiourea on the extraction of metal ions\\u000a has been investigated. Back-extraction studies were carried out to strip

S. M. Hasany; Imtiaz Hanif



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

Microsoft Academic Search

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

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



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

NASA Astrophysics Data System (ADS)

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

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



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

NASA Astrophysics Data System (ADS)

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

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



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

NASA Astrophysics Data System (ADS)

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

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



Minimal Number of Generators and Minimum Order of a Non-Abelian Group whose Elements Commute with Their Endomorphic Images  

E-print Network

A group in which every element commutes with its endomorphic images is called an $E$-group. If $p$ is a prime number, a $p$-group $G$ which is an $E$-group is called a $pE$-group. Every abelian group is obviously an $E$-group. We prove that every 2-generator $E$-group is abelian and that all 3-generator $E$-groups are nilpotent of class at most 2. It is also proved that every infinite 3-generator $E$-group is abelian. We conjecture that every finite 3-generator $E$-group should be abelian. Moreover we show that the minimum order of a non-abelian $pE$-group is $p^8$ for any odd prime number $p$ and this order is $2^7$ for $p=2$. Some of these results are proved for a class wider than the class of $E$-groups.

Abdollahi, Alireza; Hassanabadi, A Mohammadi



Pixe analysis of the platinum group elements preconcentrated from geological samples  

NASA Astrophysics Data System (ADS)

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

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



Distinction of Staphylococcal Cassette Chromosome mec type V elements from Staphylococcus aureus ST398.  


Methicillin resistant S. aureus (MRSA) is a major threat for human health and well-being. In recent years, it has become clear that livestock is a potential reservoir for MRSA, most livestock-associated isolates belonging to the ST398 lineage. Importantly, ST398 strains were also reported as causative agents of severe invasive infections in humans with no evidence for livestock associations. Here we document the sequence of the J1 region of the type V (5C2&5) SCCmec element and its right chromosomal junction in the clinical PVL-positive ST398 MRSA isolate UMCG-M4. Sequence comparisons show that this SCCmec element and related type V elements from other S. aureus isolates share a common core structure, but differ substantially in the so-called J1 region. Additional PCR analyses and typing studies indicate that the J1 region of strain UMCG-M4 is specific for SCCmec elements of PVL-positive ST398 isolates. Lastly, we show that the sequenced right chromosomal junction is invariant in strains of the ST398 lineage. PMID:23786828

Chlebowicz, Monika A; Bosch, Thijs; Sabat, Artur J; Arends, Jan P; Grundmann, Hajo; van Dijl, Jan Maarten; Buist, Girbe



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

NASA Astrophysics Data System (ADS)

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

Werner, Klaus



Identification of human DNA helicase V with the far upstream element-binding protein.  


The properties of human DNA helicase V (HDH V) were studied in greater detail following an improved purification procedure. From 450 g of cultured cells, <0.1 mg of pure protein was isolated. HDH V unwinds DNA unidirectionally by moving in the 3' to 5' direction along the bound strand in an ATP- and Mg(2+)-dependent fashion. The enzyme is not processive and can also unwind partial RNA-RNA duplexes such as HDH IV and HDH VIII. The M:(r) determined by SDS-PAGE (66 kDa) corresponds to that measured under native conditions, suggesting that HDH V exists as a monomer in the nucleus. Microsequencing of the purified HDH V shows that this enzyme is identical to the far upstream element-binding protein (FBP), a protein that stimulates the activity of the c-myc gene by binding specifically to the 'FUSE' DNA region localized upstream of its promoter. The sequence of HDH V/FBP contains RGG motifs like HDH IV/nucleolin, HDH VIII/G3BP as well as other human RNA and DNA helicases identified by other laboratories. PMID:11222755

Vindigni, A; Ochem, A; Triolo, G; Falaschi, A



Trithorax- and Polycomb-Group Response Elements within an Ultrabithorax Transcription Maintenance Unit Consist of Closely Situated but Separable Sequences†  

PubMed Central

In Drosophila, two classes of genes, the trithorax group and the Polycomb group, are required in concert to maintain gene expression by regulating chromatin structure. We have identified Trithorax protein (TRX) binding elements within the bithorax complex and have found that within the bxd/pbx regulatory region these elements are functionally relevant for normal expression patterns in embryos and confer TRX binding in vivo. TRX was localized to three closely situated sites within a 3-kb chromatin maintenance unit with a modular structure. Results of an in vivo analysis showed that these DNA fragments (each ?400 bp) contain both TRX- and Polycomb-group response elements (TREs and PREs) and that in the context of the endogenous Ultrabithorax gene, all of these elements are essential for proper maintenance of expression in embryos. Dissection of one of these maintenance modules showed that TRX- and Polycomb-group responsiveness is conferred by neighboring but separable DNA sequences, suggesting that independent protein complexes are formed at their respective response elements. Furthermore, we have found that the activity of this TRE requires a sequence (?90 bp) which maps to within several tens of base pairs from the closest neighboring PRE and that the PRE activity in one of the elements may require a binding site for PHO, the protein product of the Polycomb-group gene pleiohomeotic. Our results show that long-range maintenance of Ultrabithorax expression requires a complex element composed of cooperating modules, each capable of interacting with both positive and negative chromatin regulators. PMID:10373568

Tillib, Sergei; Petruk, Svetlana; Sedkov, Yurii; Kuzin, Alexander; Fujioka, Miki; Goto, Tadaatsu; Mazo, Alexander



Ages, metallicities and $?$-element enhancement for galaxies in Hickson compact groups  

E-print Network

Central velocity dispersions and eight line-strength Lick indices have been determined from 1.3${\\rm \\AA}$ resolution long-slit spectra of 16 elliptical galaxies in Hickson compact groups. These data were used to determine galaxy properties (ages, metallicities and $\\alpha$-element enhancements) and allowed a comparison with the parameters determined for a sample of galaxies in lower density environments, studied by Gonz\\'alez (1993). The stellar population parameters were derived by comparison to single stellar population models of Thomas et al. (2003) and to a new set of SSP models for the indices Mg$_2$, Fe5270 and Fe5335 based on synthetic spetra. These models, based on an update version of the fitting functions presented in Barbuy et al. (2003), are fully described here. Our main results are: (1) the two samples have similar mean values for the metallicities and [$\\alpha$/Fe] ratios, (2) the majority of the galaxies in compact groups seem to be old (median age of 14 Gyr for eight galaxies for which ages could be derived), in agreement with recent work by Proctor et al. (2004). These findings support two possible scenarios: compact groups are either young systems whose members have recently assembled and had not enough time to experience any merging yet or, instead, they are old systems that have avoided merging since their time of formation.

C. Mendes de Oliveira; P. Coelho; J. J. González; B. Barbuy



On the role of group I elements in ZnO  

NASA Astrophysics Data System (ADS)

Diffusion of Li, Na and K into single-crystal substrates of ZnO was performed. We compare the results with ZnO epitaxial films doped with the respective elements during growth. The diffused and in-situ doped layers were studied using mass spectroscopy and low temperature photoluminescence spectroscopy. Li and Na are known to produce deep acceptor centers which give rise to shallow donor to deep acceptor recombinations in the visible spectral region. We will demonstrate that shallow acceptors are also introduced, having binding energies around 300 meV. A donor acceptor pair recombination (zero phonon line at 3.05 eV) with LO phonon replica is observed. We further investigated bulk ZnO crystals which contained the deep Li acceptor by thermal treatments under H2 atmospheres. With increasing annealing temperature shallow donors are introduced as monitored by EPR while the EPR signal of the neutral Li acceptors decreases. Quite unexpectedly, the shallow Li acceptor centre which is not present in the as-grown state is also created.

Meyer, B. K.; Stehr, J.; Hofstaetter, A.; Volbers, N.; Zeuner, A.; Sann, J.



Biomonitoring of airborne platinum group elements in urban traffic police officers.  


In the present study, an attempt was made to study the levels of platinum (Pt), palladium (Pd), and rhodium (Rh) in respirable suspended particulate matter samples and respective blood samples of occupationally exposed traffic personnel in selected sites of Hyderabad city. The maximum concentration of platinum group elements in air dust samples of Hyderabad city were as follows: Pt = 1,416 µg/m(3), Pd = 1,024 µg/m(3), and Rh = 1,352 µg/m(3). The blood samples of occupationally exposed personnel of Hyderabad city showed Pt as high as 6.65, Pd as high as 2.15, and Rh as high as 4.95 µg/l. The results showed an important aspect of bioaccumulation tendency of these metals with increase in age and years of occupational exposure. PMID:25542147

Kamala, C T; Balaram, V; Satyanarayanan, M; Kiran Kumar, A; Subramanyam, K S V



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

NASA Astrophysics Data System (ADS)

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

Wood, Michael P.; Nave, Gillian



Accumulation of platinum group elements by the marine gastropod Littorina littorea.  


The accumulation and trophic transfer of the platinum group elements (PGE): Rh, Pd and Pt; have been studied in short-term (5 day) exposures conducted in aquaria containing the marine macroalga, Ulva lactuca, and/or the grazing mollusc, Littorina littorea. Metals added to sea water (to concentrations of 20 ?g L?¹) were taken up by U. lactuca in the order Rh, Pt > Pd and by L. littorea in the order Pd ? Pt ? Rh, with greatest metal accumulation in the latter generally occurring in the visceral complex and kidney. When fed contaminated alga, accumulation of Rh and Pd by L. littorea, relative to total available metal, increased by an order of magnitude, while accumulation of Pt was not readily detected. We conclude that the diet is the most important vector for accumulation of Rh and Pd, while accumulation of Pt appears to proceed mainly from the aqueous phase. PMID:21237543

Mulholland, Rachel; Turner, Andrew



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

NASA Astrophysics Data System (ADS)

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

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



Leaves of Phragmites australis as potential atmospheric biomonitors of Platinum Group Elements.  


The increasing emissions of Platinum Group Elements (PGEs), namely Pt, Pd and Rh, may pose a significant risk to ecosystem processes and human health. A periodic assessment of PGEs distribution in the environment is thus of the utmost importance for the implementation of timely measures of mitigation. Although several studies have quantified PGEs in different life forms such as mammals, birds, fish, crustaceans, algae, mosses and even human beings, data about vascular plants need further surveys. This study aimed to test the suitability of the grass Phragmites australis (common reed) as a biomonitor of PGEs atmospheric pollution. The results showed that Pd and Pt concentrations in leaves are significantly higher in urban areas. In particular, Pd showed the highest range of values in line with current studies that consider palladium as the main element of traffic-related pollution. Overall, the leaves of Phragmites australis reflected the different gradient of PGEs emissions, and may thus be considered as potential biomonitors of atmospheric pollution. PMID:25596354

Bonanno, Giuseppe; Pavone, Pietro



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

NASA Astrophysics Data System (ADS)

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

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



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

NASA Astrophysics Data System (ADS)

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

Kissin, S. A.



Implementation of Hybrid V-Cycle Multilevel Methods for Mixed Finite Element Systems with Penalty  

NASA Technical Reports Server (NTRS)

The goal of this paper is the implementation of hybrid V-cycle hierarchical multilevel methods for the indefinite discrete systems which arise when a mixed finite element approximation is used to solve elliptic boundary value problems. By introducing a penalty parameter, the perturbed indefinite system can be reduced to a symmetric positive definite system containing the small penalty parameter for the velocity unknown alone. We stabilize the hierarchical spatial decomposition approach proposed by Cai, Goldstein, and Pasciak for the reduced system. We demonstrate that the relative condition number of the preconditioner is bounded uniformly with respect to the penalty parameter, the number of levels and possible jumps of the coefficients as long as they occur only across the edges of the coarsest elements.

Lai, Chen-Yao G.



Finite automata for Schreier graphs of virtually free groups Pedro V. Silva  

E-print Network

Finite automata for Schreier graphs of virtually free groups Pedro V. Silva Centro de Matem foldings, Schreier graphs, finitely generated subgroups ABSTRACT The Stallings construction for f an efficient computation of the core of a Schreier graph based on edge folding. It is proved that those groups

Ventura, Enric


Platinum group elements in automobile catalysts: characterization, sources and environmental mobility  

NASA Astrophysics Data System (ADS)

The platinum group elements (PGE) comprise Ru, Rh, Pd, Os, Ir, and Pt. The PGE are extremely siderophile and most of the elements were during the Earth differentiation partitioned into the core. The average natural concentration of PGE in Earth's crust is low and range of 0.X - X0 ?g kg-1. During the magmatic process the PGE are strongly partitioned into sulphides and Ni minerals. The distribution of PGE and increase of their emissions in the environment are mostly related to the use of automobile catalyst (AC) in car engines (in USA since 1975, in Europe since 1986). The ACs consist of a honeycomb support (made from ?-Al2O3 or cordierite with trace element admixtures - mostly lanthanides and Zr) coated with Pt, Pd and Rh in different ratios. While AC for gasoline engines contain a mixture of Pt-Pd-Rh or Pd-Rh, AC for diesel engines are composed only of Pt. New and aged AC of gasoline and diesel engines, AC standard reference materials, tunnel dust from Prague and tunnel dust reference materials were studied using scanning electron microscopy, electron microanalyses, X-ray diffraction and chemical analyses using inductively coupled plasma mass spectrometry. The studied ACs differ in phase and elemental composition and PGE contents. The matrix of the gasoline AC is composed of Al, Zr, Ce, Ba oxides with Rh, Pd and Pt coatings. The support of diesel AC is composed of Mg, Al, Fe, Ti and Ca silicates with Pt coatings. Aged gasoline AC exhibit higher Mg, Mn, Zn and Pb contents compared to the new AC. Aged diesel AC differs in higher Zn and Ba contents compared to the new one. Both aged and new AC does not differ in total PGE contents. Leaching experiments were done with AC, real samples of tunnel dusts and reference materials with inorganic (Cl-, HPO42-) and organic (low and high molecular weight) complexing solutions. The solubility experiments indicate that PGE mobilization from ACs is dependent on particle type, time and complexing medium.

Mihaljevic, Martin; Ettler, Vojtech; Strnad, Ladislav; Sebek, Ondrej; Stedry, Robin; Adamec, Vladimir



Analytic simulation of the backscattering of hundreds eV positrons from elemental solids  

NASA Astrophysics Data System (ADS)

Backscattering (Bcs) coefficients for low-energy positrons (˜100 eV) from elemental solids have been simulated using an analytic approach. The model is based on the use of the transport cross-sections (TCSs) and the stopping power calculated from partial wave methods and the best-fit stopping power data of Ashley, respectively. The new result is an extension of recent calculations in the medium energy range. Comparisons, when possible, with experimental and Monte-Carlo (MC) simulation data have been made.

Chaoui, Z.



Architectural and Functional Diversity of Polycomb Group Response Elements in Drosophila  

PubMed Central

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.



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

Code of Federal Regulations, 2014 CFR

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



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

Code of Federal Regulations, 2012 CFR

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



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

Code of Federal Regulations, 2013 CFR

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



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

Code of Federal Regulations, 2010 CFR

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



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

Code of Federal Regulations, 2011 CFR

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



Elemental copper nanoparticle toxicity to different trophic groups involved in anaerobic and anoxic wastewater treatment processes.  


Elemental copper nanoparticles (Cu(0) NPs) are potentially inhibitory to the different key microbial trophic groups involved in biological wastewater treatment processes. Cu-based NPs are known to be toxic to methanogens at low concentrations. However, very little is known about the toxic effect of Cu(0) NPs on other microbial groups involved in either upper trophic levels of anaerobic digestion or anoxic nitrogen removal processes. This study evaluated the toxicity of Cu(0) NPs to glucose fermentation, syntrophic propionate oxidation and denitrification in shaken batch bioassays with soluble substrates. Batch experiments were also supplemented with CuCl2 to evaluate the inhibitory impact of soluble Cu(II) ions. Syntrophic propionate oxidation and glucose fermentation were the least and most inhibited processes with inhibition constant (Ki) values of 0.202 and 0.047mM of added Cu(0) NPs, respectively. Further analyses revealed that the Ki values calculated as a function of the free soluble Cu concentration were <0.003mM for every biological process tested and most of these Ki values were similar in order of magnitude regardless of whether the Cu source was CuCl2 or Cu(0) NPs. The results taken as a whole indicate that Cu(0) NPs are toxic to all the microbial processes studied. Therefore, Cu(0) NPs can potentially be an important inhibitor of anaerobic wastewater treatment processes that rely on these trophic groups. The evidence suggests that the inhibitory impact of Cu(0) NPs was mainly due to the release of toxic Cu(II) ions originating from the corrosion and dissolution of Cu(0) NPs. PMID:25634735

Gonzalez-Estrella, Jorge; Puyol, Daniel; Gallagher, Sara; Sierra-Alvarez, Reyes; Field, Jim A



Photochemistry and charge transfer chemistry of the platinum group elements. Progress report, May 1, 1991--April 30, 1992  

SciTech Connect

Significant progress has been made on the photochemistry and photophysics of platinum group element dithiolate complexes. The specific systems under investigation are square planar complexes of Pt(II) containing a dithiolate chelate and two other donor groups to complete the coordination sphere. The donor groups may be amines, imines, phosphines, phosphites or olefins, and they can be either monodentate or joined together as part of a chelate ring.

Eisenberg, R.



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

NASA Technical Reports Server (NTRS)

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

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



Development of metallographic preparation techniques for group IVA and VA elements  

SciTech Connect

Existing metallographic preparation techniques for Group IVA/VA (e.g. V, Ti, Ta, Hf, Nb, Zr) materials do not reveal all microstructural features inherent to the process history. As a result, new techniques have been developed and compared to existing procedures. For example, in pure tantalum, the new procedure exposes a substructure that is not evident using previously published techniques. In niobium, better grain boundary delineation is possible with the new process. Similar results are evident for titanium, zirconium, vanadium, and hafnium. The new preparation stage includes a chemical polish and etchant. The chemical polish was found to eliminate problems associated with the mechanical polish. Specifically, the chemical polish removes the worked surface and eliminates smearing. The etching stage serves to delineate the grain boundaries, and in some cases allows bright field as well as polarized or differential interference contrast (DIC) for optical examination. Finally, optical lighting conditions to enhance the observations available with the optimized procedure will be discussed.

Bingert, S. A. (Sherri A.); Abeln, T. G. (Terri G.); Thoma, D. J. (Dan J.); Cooley, J. C. (Jason C.); Hults, W. L. (William L.); Kelly, A. M. (Anna Marie)



29 CFR Appendix V to Part 1918 - Basic Elements of a First Aid Training Program (Non-mandatory)  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Basic Elements of a First Aid Training Program (Non-mandatory) Part 1918—Basic Elements of a First Aid Training Program (Non-mandatory) Note...businesses, institutions teaching first aid, and the recipients of first aid...



29 CFR Appendix V to Part 1918 - Basic Elements of a First Aid Training Program (Non-mandatory)  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Basic Elements of a First Aid Training Program (Non-mandatory) Part 1918—Basic Elements of a First Aid Training Program (Non-mandatory) Note...businesses, institutions teaching first aid, and the recipients of first aid...



29 CFR Appendix V to Part 1918 - Basic Elements of a First Aid Training Program (Non-mandatory)  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Basic Elements of a First Aid Training Program (Non-mandatory) Part 1918—Basic Elements of a First Aid Training Program (Non-mandatory) Note...businesses, institutions teaching first aid, and the recipients of first aid...



Contribution of Exogenous Genetic Elements to the Group A Streptococcus Metagenome  

PubMed Central

Variation in gene content among strains of a bacterial species contributes to biomedically relevant differences in phenotypes such as virulence and antimicrobial resistance. Group A Streptococcus (GAS) causes a diverse array of human infections and sequelae, and exhibits a complex pathogenic behavior. To enhance our understanding of genotype-phenotype relationships in this important pathogen, we determined the complete genome sequences of four GAS strains expressing M protein serotypes (M2, M4, and 2 M12) that commonly cause noninvasive and invasive infections. These sequences were compared with eight previously determined GAS genomes and regions of variably present gene content were assessed. Consistent with the previously determined genomes, each of the new genomes is ?1.9 Mb in size, with ?10% of the gene content of each encoded on variably present exogenous genetic elements. Like the other GAS genomes, these four genomes are polylysogenic and prophage encode the majority of the variably present gene content of each. In contrast to most of the previously determined genomes, multiple exogenous integrated conjugative elements (ICEs) with characteristics of conjugative transposons and plasmids are present in these new genomes. Cumulatively, 242 new GAS metagenome genes were identified that were not present in the previously sequenced genomes. Importantly, ICEs accounted for 41% of the new GAS metagenome gene content identified in these four genomes. Two large ICEs, designated 2096-RD.2 (63 kb) and 10750-RD.2 (49 kb), have multiple genes encoding resistance to antimicrobial agents, including tetracycline and erythromycin, respectively. Also resident on these ICEs are three genes encoding inferred extracellular proteins of unknown function, including a predicted cell surface protein that is only present in the genome of the serotype M12 strain cultured from a patient with acute poststreptococcal glomerulonephritis. The data provide new information about the GAS metagenome and will assist studies of pathogenesis, antimicrobial resistance, and population genomics. PMID:17726530

Beres, Stephen B.; Musser, James M.



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

NASA Astrophysics Data System (ADS)

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

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



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


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

PubMed Central

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

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



Trithorax- and Polycomb-group response elements within an Ultrabithorax transcription maintenance unit consist of closely situated but separable sequences.  


In Drosophila, two classes of genes, the trithorax group and the Polycomb group, are required in concert to maintain gene expression by regulating chromatin structure. We have identified Trithorax protein (TRX) binding elements within the bithorax complex and have found that within the bxd/pbx regulatory region these elements are functionally relevant for normal expression patterns in embryos and confer TRX binding in vivo. TRX was localized to three closely situated sites within a 3-kb chromatin maintenance unit with a modular structure. Results of an in vivo analysis showed that these DNA fragments (each approximately 400 bp) contain both TRX- and Polycomb-group response elements (TREs and PREs) and that in the context of the endogenous Ultrabithorax gene, all of these elements are essential for proper maintenance of expression in embryos. Dissection of one of these maintenance modules showed that TRX- and Polycomb-group responsiveness is conferred by neighboring but separable DNA sequences, suggesting that independent protein complexes are formed at their respective response elements. Furthermore, we have found that the activity of this TRE requires a sequence (approximately 90 bp) which maps to within several tens of base pairs from the closest neighboring PRE and that the PRE activity in one of the elements may require a binding site for PHO, the protein product of the Polycomb-group gene pleiohomeotic. Our results show that long-range maintenance of Ultrabithorax expression requires a complex element composed of cooperating modules, each capable of interacting with both positive and negative chromatin regulators. PMID:10373568

Tillib, S; Petruk, S; Sedkov, Y; Kuzin, A; Fujioka, M; Goto, T; Mazo, A



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


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

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



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


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

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



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

NASA Astrophysics Data System (ADS)

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

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



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


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

Yang, Xiufeng; Liu, Moubin; Peng, Shiliu



The Ontong Java Plateau: Evidence of Sulfide Involvement Using Platinum Group Elements.  

NASA Astrophysics Data System (ADS)

Ontong Java Plateau (OJP) basalts in the SW Pacific have been produced by large degrees of partial melting (Mahoney and Spencer, 1991, EPSL, 104:196-210; Neal et al., 1997, AGU Mono. 100:183-216), consistent with decompression melting of a surfacing plume head originating at the core-mantle boundary (CMB) (Coffin and Eldholm, 1993, Sci. Am., 269:42-49). Due to significant fractional crystallization (up to 50%, Neal et al., ibid.) and the resulting low Os abundances of the OJP basalts, Os isotope techniques used to demonstrate a CMB origin for other plumes (Walker et al., 1995, Science, 269:819-822 and 1997, GCA, 61:3145-3160) cannot be easily applied to the OJP. Geophysical modeling suggests chemical interactions across the CMB would occur (~3-6%) (e.g., Kellogg and King, 1993, GRL, 20:379-382; Boehler et al., 1995, Chem. Geol., 120:199-205), which would produce enriched siderophile signatures in the resulting lower mantle-core mixture. The high degree of partial melting (>20%)(Michael, 1999, Geochem. Geophys. Geosyst.) supports the view that any platinum group elements (PGEs) as well as sulfides would be partitioned into the OJP plume rather than remaining in the source (Barnes et al., 1985, Chem. Geol. 53, 303-323). PGE abundances (excluding Os) have been analyzed in OJP basalts from the islands of Malaita and Makira. Melting models using spinel peridotite demonstrate the PGE abundances in the OJP basalts cannot be generated from typical upper mantle. Melting models using primitive mantle mixed with a small amount of bulk core material can produce the PGE patterns and abundances present in OJP basalts (Ely and Neal, 1999, EOS, 80:F1103). Adjacent samples from separate flows indicate that magma chamber fractional crystallization had little effect on PGE abundances. PGE abundances are also remarkably uniform across sequences of flows, except for the variable removal of Pd by weathering. Primitive mantle-normalized patterns using PGEs and trace elements demonstrate that there may have been PGE removal by sulfides in some samples. However, any sulfide removal of PGEs argues for even higher PGE abundances in the source, assumed to be a small amount of bulk core material mixed into the OJP plume source.

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



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

NASA Astrophysics Data System (ADS)

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

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



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


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

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



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

NASA Astrophysics Data System (ADS)

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

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



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


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

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



Complex anthropogenic sources of platinum group elements in aerosols on Cape Cod, USA.  


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



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


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

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



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


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

Wiseman, Clare L S; Zereini, Fathi



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


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

Li, Pei-Miao; Gao, Xue-Lu



Group V Secretory Phospholipase A2 Modulates Phagosome Maturation and Regulates the Innate Immune Response  

E-print Network

Response against Candida albicans1 Barbara Balestrieri,*2 Akiko Maekawa,* Wei Xing,* Michael H. Gelb lacking group V sPLA2 had delays in phagocy- tosis, phagosome maturation, and killing of Candida albicans, dectin-1 is essential for binding and uptake of zymosan (7) and for reactive oxygen species (ROS)3

Gelb, Michael


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

E-print Network

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

Rosen, Jay


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

E-print Network

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

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



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

E-print Network

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

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



Should an Obsessive-Compulsive Spectrum Grouping of Disorders Be Included in DSM-V?  

PubMed Central

The obsessive-compulsive (OC) spectrum has been discussed in the literature for two decades. Proponents of this concept propose that certain disorders characterized by repetitive thoughts and/or behaviors are related to obsessive-compulsive disorder (OCD), and suggest that such disorders be grouped together in the same category (i.e., grouping, or “chapter”) in DSM. This paper addresses this topic and presents options and preliminary recommendations to be considered for DSM-V. The paper builds upon and extends prior reviews of this topic that were prepared for and discussed at a DSM-V Research Planning Conference on Obsessive-Compulsive Spectrum Disorders held in 2006. Our preliminary recommendation is that an OC-spectrum grouping of disorders be included in DSM-V. Furthermore, we preliminarily recommend that consideration be given to including this group of disorders within a larger supraordinate category of “Anxiety and Obsessive-Compulsive Spectrum Disorders.” These preliminary recommendations must be evaluated in light of recommendations for, and constraints upon, the overall structure of DSM-V. PMID:20533367

Phillips, Katharine A.; Stein, Dan J.; Rauch, Scott; Hollander, Eric; Fallon, Brian A.; Barsky, Arthur; Fineberg, Naomi; Mataix-Cols, David; Ferrão, Ygor Arzeno; Saxena, Sanjaya; Wilhelm, Sabine; Kelly, Megan M.; Clark, Lee Anna; Pinto, Anthony; Bienvenu, O. Joseph; Farrow, Joanne; Leckman, James



I. ASCRC General Education Form Group V. Literary and Artistic Studies, IX. American and European  

E-print Network

I. ASCRC General Education Form Group V. Literary and Artistic Studies, IX. American and European Perspectives Dept/Program MCLL Course # GERM 361, LS 282, MCLG 222 Course Title History of German Cinema and Austrian contribution to American cinema, East German film, the New German Cinema, and recent developments

Vonessen, Nikolaus


arXiv:hep-ph/0204316v129Apr2002 THE QCD/SM WORKING GROUP  

E-print Network

arXiv:hep-ph/0204316v129Apr2002 THE QCD/SM WORKING GROUP: Summary Report Conveners: W. GIELE1, E. GEHRMANN-DE RIDDER2, W. GIELE1 , E.W.N. GLOVER2, M. GRAZZINI20, J.-PH. GUILLET6 , G. HEINRICH2, J. HUSTON4

Sjöstrand, Torbjörn


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

E-print Network

I. ASCRC General Education Form Group V. Literary and Artistic Studies Dept/Program English Course:// Students develop a familiarity with the significant forms of artistic representation that depict same construction, analyze and explore the way artistic representation are influenced by and influence perceived

Vonessen, Nikolaus


Differences in the promotional effect of the group IA elements on unsupported copper catalysts for carbon monoxide hydrogenation  

Microsoft Academic Search

The differences in promotional effect of the Group IA elements on unsupported copper catalysts for carbon monoxide hydrogenation have been examined. Methanol was selectivity produced on all catalysts at 523 K, 5 MPa, and with a feed gas of molar composition Hâ\\/CO = 2. When normalized with respect to surface area, the methanol synthesis rate was found to increase by

G. R. Sheffer; T. S. King




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...


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



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: [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)



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

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



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

PubMed Central

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

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



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

Microsoft Academic Search

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,

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



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

Microsoft Academic Search

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,

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



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



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

USGS Publications Warehouse

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

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



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



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)



Les Houches 2013: Physics at TeV Colliders: New Physics Working Group Report  

E-print Network

We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 3--21 June, 2013). Our report includes new computational tool developments, studies of the implications of the Higgs boson discovery on new physics, important signatures for searches for natural new physics at the LHC, new studies of flavour aspects of new physics, and assessments of the interplay between direct dark matter searches and the LHC.

G. Brooijmans; R. Contino; B. Fuks; F. Moortgat; P. Richardson; S. Sekmen; A. Weiler; A. Alloul; A. Arbey; J. Baglio; D. Barducci; A. J. Barr; L. Basso; M. Battaglia; G. Bélanger; A. Belyaev; J. Bernon; A. Bharucha; O. Bondu; F. Boudjema; E. Boos; M. Buchkremer; V. Bunichev; G. Cacciapaglia; G. Chalons; E. Conte; M. J. Dolan; A. Deandrea; K. De Causmaecker; A. Djouadi; B. Dumont; J. Ellis; C. Englert; A. Falkowski; S. Fichet; T. Flacke; A. Gaz; M. Ghezzi; R. Godbole; A. Goudelis; M. Gouzevitch; D. Greco; R. Grober; C. Grojean; D. Guadagnoli; J. F. Gunion; B. Herrmann; J. Kalinowski; J. H. Kim; S. Kraml; M. E. Krauss; S. Kulkarni; S. J. Lee; S. H. Lim; D. Liu; F. Mahmoudi; Y. Maravin; A. Massironi; L. Mitzka; K. Mohan; G. Moreau; M. M. Mühlleitner; D. T. Nhung; B. O'Leary; A. Oliveira; L. Panizzi; D. Pappadopulo; S. Pataraia; W. Porod; A. Pukhov; F. Riva; J. Rojo; R. Rosenfeld; J. Ruiz-Álvarez; H. Rzehak; V. Sanz; D. Sengupta; M. Spannowsky; M. Spira; J. Streicher; N. Strobbe; A. Thamm; M. Thomas; R. Torre; W. Waltenberger; K. Walz; A. Wilcock; A. Wulzer; F. Würthwein; C. Wymant



Synthesis and characterization of group V metal carbide and nitride catalysts  

Microsoft Academic Search

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

Heock-Hoi Kwon



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


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

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



Thermochemistry of organic, elementorganic and inorganic species. Part XXI: Enthalpies of formation for bi- and triradicals of main group elements’ halogenides  

NASA Astrophysics Data System (ADS)

General trends in thermochemistry of bi- and triradicals as the fragments of halogenated molecules of main group elements :EX (:EHX; :EX 2) and triradicals ·:EX, respectively, where X-halogens F-I were found for the first time. The enthalpy of formation for methylene CH 2 was drastically changed in present work with adopted values 79 ( 3B 1) and 88 ( 1A 1) compared with currently used values ˜93 and ˜102 kcal mol -1, respectively. This happened mainly because of the drastic change in the enthalpy of formation for ketene CH 2dbnd C dbnd O molecule from currently used value -11.4 to -24 kcal mol -1 [A.V. Golovin, D.A. Ponomarev, V.V. Takhistov, This Journal 524 (2000) 259] which was the source of experimental determination of ?Hf0 :CH 2. Other experimental data are provided for support of the lower values of the ?Hf0 for :CH 2. It was established that halogens F-I stabilize all biradicals :EX (E = B-Tl, N-Bi) and :EHX (:EX 2) (E = C-Pb) compared with the free radicals of these elements. This was interpreted by essentially smaller thermodynamic stability of bi- compared with mono (free)radicals the former extracting larger stabilization at H ? X replacement from the same halogen compared with more stable free radicals. The expected increase in stabilization of biradicals is observed when coming down the periodic table while due to lower stability of biradicals all halogens reveal similar (contrary to free radicals) stabilization effects. Finding unknown values and correcting some literature data on the enthalpies of formation for mono-, bi- and triradicals we could estimate their thermodynamic stabilities. It was established that only about 40 molecules, radicals and biradicals from more than 800 hydrides and halogenides possess higher?Hf0 values compared with their fragments with elements in lower valent states with H 2 (rarely HX) as a partner. This might be treated only in the sense that the parent species are less stable than the system [fragment + H 2 (or HX)] rather than as the support of the higher thermodynamic stability of an element in its lower valent state. The thermodynamic stability of such state may be found only by the comparison of the consecutive bond dissociation energies (BDEs) in parent molecules like PbH 3X ? ·PbH 2X (BDE 1) ? :PbHX (BDE 2) ? ·:PbX (BDE 3) and only if BDE 2 < 0 one can declare the larger thermodynamic stability of element in lower valent state. But this does not happen with any species studied in this work. This means that thermodynamic stability quite definitely decreases in the row molecule > free radical > biradical > triradical > :E: (C-Pb) contrary to the current opinion of larger thermodynamic stability of lower valent states for, say, thallium or lead. The detailed analysis of many computational results related to thermochemistry of halogenated main group elements is performed with quite definite result that neither ab initio, DFT, semi-empirical methods (or their combination) can be trusted either in support of known or prediction of unknown values of the enthalpies of formation while the empirical approach, elaborated in this work, solves the problem of calculation of the enthalpies of formation and search of general trends in structure/enthalpy of formation for halogenated main group elements.

Ponomarev, Dmitry; Takhistov, Viatcheslav; Slayden, Suzanne; Liebman, Joel



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.



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)




Microsoft Academic Search

A 0.2 g sample of carbide (270 mesh) was treated with 50 ml of solution ; for 24 hours in the cold and for 2 hours on boiling. The residue was filtered, ; dried and weighed to determine the chemical stability. The carbides were tested ; with HCl(sp. gr=1.19),1:1 HCl, HNOâ(,1:1 HNOâ, HâSO\\/; sub 4\\/ (sp. gr = 1.84) 1:4




Isotope Anomalies in the Fe-group Elements in Meteorites and Connection to Nucleosynthesis in AGB Stars  

E-print Network

We study the effects of neutron captures in AGB stars on \\oq Fe-group\\cqb elements, with an emphasis on Cr, Fe, and Ni. These elements show anomalies in $^{54}$Cr, $^{58}$Fe, and $^{64}$Ni in solar-system materials, which are commonly attributed to SNe. However, as large fractions of the interstellar medium (ISM) were reprocessed in AGB stars, these elements were reprocessed, too. We calculate the effects of such reprocessing on Cr, Fe, and Ni through 1.5\\msb and 3\\msb AGB models, adopting solar and 1/3 solar metallicities. All cases produce excesses of $^{54}$Cr, $^{58}$Fe, and $^{64}$Ni, while the other isotopes are little altered; hence, the observations may be explained by AGB processing. The results are robust and not dependent on the detailed initial isotopic composition. Consequences for other \\oq Fe group\\cqb elements are then explored. They include $^{50}$Ti excesses, and some production of $^{46,47,49}$Ti. In many circumstellar condensates, Ti quantitatively reflects these effects of AGB neutron cap...

Wasserburg, Gerald J; Busso, Maurizio



Design and measurements of test element group wafer thinned to 10 ?m for 3D system in package  

Microsoft Academic Search

We designed and measured test element group wafers thinned to 10 ?m for 3D system in package. The n-well p-Si diodes in 10 ?m thick wafer showed increasing of the reverse saturation current in comparison to the currents in 20 ?m, 30 ?m or 640 ?m thick wafer. While the pMOSFETs and nMOSFETs in 10 ?m thick wafer showed no

Akihiro Ikeda; Tomonori Kuwata; Satoru Kajiwara; Tsuyoshi Fujimura; Hisao Kuriyaki; Reiji Hattori; Hiroshi Ogi; Kiyoshi Hamaguchi; Yukinori Kuroki



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

Microsoft Academic Search

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

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



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

Microsoft Academic Search

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

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



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

ERIC Educational Resources Information Center

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

Vick, Randy M.



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



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


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

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



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

NASA Astrophysics Data System (ADS)

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

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



The behaviour of platinum-group elements in basalts from the East Greenland rifted margin  

Microsoft Academic Search

. The continental flood basalts of the East Greenland volcanic rifted margin were extruded during continental breakup above the ancestral Iceland mantle plume at 55 Ma. Three distinct magma types, the low-Ti, high-Ti and very high-Ti series (LTS, HTS and VHTS respectively), are found intercalated in the ~6-km-thick Plateau Lava sequence. Incompatible trace elements indicate that the LTS are derived

Peter Momme; Christian Tegner; Kent C. Brooks; Reid R. Keays



The VIPER elements of trypanosomes constitute a novel group of tyrosine recombinase-enconding retrotransposons  

Microsoft Academic Search

VIPER was initially characterized as a 2326bp LTR-like retroelement associated to SIRE, a short interspersed repetitive element specific of Trypanosoma cruzi. It carried a single ORF that coded for a putative reverse transcriptase-RNAse H protein, suggesting that it could be a truncated copy of a longer retroelement. Herein we report the identification and characterization of a complete 4480bp long VIPER

Hernan A. Lorenzi; German Robledo; Mariano J. Levin



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

NASA Technical Reports Server (NTRS)

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

Holland, L. R.



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



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



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

USGS Publications Warehouse

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

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



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

SciTech Connect

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

Barbee, T.W. Jr.



Chromosomal Homology and Molecular Organization of Muller's Elements D and E in the Drosophila Repleta Species Group  

PubMed Central

Thirty-three DNA clones containing protein-coding genes have been used for in situ hybridization to the polytene chromosomes of two Drosophila repleta group species, D. repleta and D. buzzatii. Twenty-six clones gave positive results allowing the precise localization of 26 genes and the tentative identification of another nine. The results were fully consistent with the currently accepted chromosomal homologies and in no case was evidence for reciprocal translocations or pericentric inversions found. Most of the genes mapped to chromosomes 2 and 4 that are homologous, respectively, to chromosome arms 3R and 3L of D. melanogaster (Muller's elements E and D). The comparison of the molecular organization of these two elements between D. melanogaster and D. repleta (two species that belong to different subgenera and diverged some 62 million years ago) showed an extensive reorganization via paracentric inversions. Using a maximum likelihood procedure, we estimated that 130 paracentric inversions have become fixed in element E after the divergence of the two lineages. Therefore, the evolution rate for element E is approximately one inversion per million years. This value is comparable to previous estimates of the rate of evolution of chromosome X and yields an estimate of 4.5 inversions per million years for the whole Drosophila genome. PMID:9071584

Ranz, J. M.; Segarra, C.; Ruiz, A.



Renormalization group flow of Ho\\v{r}ava-Lifshitz gravity at low energies  

E-print Network

The functional renormalization group equation for projectable Ho\\v{r}ava-Lifshitz gravity is used to derive the non-perturbative beta functions for the Newton's constant, cosmological constant and anisotropy parameter. The resulting coupled differential equations are studied in detail and exemplary RG trajectories are constructed numerically. The beta functions possess a non-Gaussian fixed point and a one-parameter family of Gaussian fixed points. One of the Gaussian fixed points corresponds to the Einstein-Hilbert action with vanishing cosmological constant and constitutes a saddle point with one IR-attractive direction. For RG trajectories dragged into this fixed point at low energies diffeomorphism invariance is restored. The emergence of general relativity from Ho\\v{r}ava-Lifshitz gravity can thus be understood as a crossover-phenomenon where the IR behavior of the theory is controlled by this Gaussian fixed point. In particular RG trajectories with a tiny positive cosmological constant also come with an ...

Contillo, Adriano; Saueressig, Frank



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

SciTech Connect

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

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



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

SciTech Connect

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

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



Synthesis of porous and acidic complex metal oxide catalyst based on group 5 and 6 elements  

Microsoft Academic Search

Complex metal oxides of transition metals using Mo, W, V, Nb and Ta were synthesized by hydrothermal method. The synthesized complex metal oxides were characterized and the solid acid catalytic activity was tested through the Friedel-Crafts alkylation of anisole and benzyl alcohol. X-ray diffraction patterns of the obtained samples showed two peaks at 2?=22° and 46° indicating these materials have

Toru Murayama; Nozomi Kuramata; Shunsuke Takatama; Kosuke Nakatani; Shoko Izumi; Xiaodong Yi; Wataru Ueda


Group V Secretory Phospholipase A2 Modulates Phagosome Maturation and Regulates the Innate Immune Response Against Candida albicans1  

PubMed Central

Phospholipase A2 (PLA2) hydrolyzes the sn-2 position of cell membrane phospholipids to release fatty acids and lysophospholipids. We have previously reported that group V secretory PLA2 (sPLA2) translocates from the Golgi and recycling endosomes of mouse peritoneal macrophages to newly formed phagosomes and regulates the phagocytosis of zymosan, suggesting a role in innate immunity. Here we report that in macrophages lacking group V sPLA2 phagosome maturation was reduced 50–60% at early time points while the binding of zymosan was unimpaired. The ability of group V sPLA2 to regulate phagocytosis extended to phagocytosis of IgG- and complement-opsonized sheep red blood cells. Moreover, macrophages lacking group V sPLA2 had delays in phagocytosis, phagosome maturation and killing of Candida albicans. Cytokine production and eicosanoid generation were not impaired by the lack of group V sPLA2. Furthermore, in a model of systemic candidiasis, mice lacking group V sPLA2 had an increased fungal burden in the kidney, liver and spleen at day 7 post-infection and increased mortality. Thus, group V sPLA2 regulates phagocytosis through major phagocytic receptors and contributes to the innate immune response against Candida albicans by regulating phagocytosis and killing through a mechanism that is likely dependent on phagolysosome fusion. PMID:19342668

Balestrieri, Barbara; Maekawa, Akiko; Xing, Wei; Gelb, Michael H.; Katz, Howard R.; Arm, Jonathan P.



Terahertz lasers based on intracentre transitions of group V donors in uniaxially deformed silicon  

NASA Astrophysics Data System (ADS)

This paper presents a brief overview of available experimental data on the characteristics of stimulated terahertz emission (4.9 – 6.4 THz) from optically excited neutral group V donors (phosphorus, antimony, arsenic and bismuth) in crystalline silicon subjected to uniaxially compressive strain along the [100] axis. Strain is shown to have a significant effect on the characteristics in question. Optimal strain depends on the dopant and may reduce the threshold pump intensity and improve lasing efficiency. We discuss possible mechanisms behind this effect and estimate the limiting output emission parameters.

Kovalevsky, K. A.; Abrosimov, N. V.; Zhukavin, R. Kh; Pavlov, S. G.; Hübers, H. W.; Tsyplenkov, V. V.; Shastin, V. N.



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



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

Microsoft Academic Search

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

Pham Huu Tiep



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

ERIC Educational Resources Information Center

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

Moore, E. A.



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

Microsoft Academic Search

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

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



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

PubMed Central

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.



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.



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

NASA Technical Reports Server (NTRS)

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

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



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

NASA Technical Reports Server (NTRS)

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

Altshuller, Aubrey P



Osmium-Isotope and Platinum-Group-Element Systematics of Impact-Melt Rocks, Chesapeake Bay Impact Structure, Virginia, USA  

NASA Technical Reports Server (NTRS)

Osmium (Os) isotopes and platinum-group elements (PGEs) are useful for geochemically identifying a meteoritic component within impact structures, because meteorites are typically characterized by low (187)Os/(188)Os ratios and high PGE concentrations. In contrast, most types of crustal target rocks have high radiogenic Os and very low PGE concentrations. We have examined Os isotope and PGE systematics of impact-melt rocks and pre-impact target rocks from a 2004 test hole in the late Eocene Chesapeake Bay impact structure and from nearby coreholes. Our goal is to determine the proportion of the projectile component in the melt rock Additional information is included in the original extended abstract.

Lee, Seung Ryeol; Wright Horton, J., Jr.; Walker, Richard J.



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

NASA Astrophysics Data System (ADS)

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

Dolph, Melissa Commisso; Santeufemio, Christopher



Multiple bonds between transition metals and main-group elements. 73. Synthetic routes to rhenium(V) alkyl and rhenium(VII) alkylidyne complexes. X-ray crystal structures of (. eta. sup 5 -C sub 5 Me sub 5 )Re( double bond O)(CH sub 3 )(CH sub 2 C(CH sub 3 ) sub 3 ) and (. eta. sup 5 -C sub 5 Me sub 5 )(Br) sub 3 Re triple bond CC(CH sub 3 ) sub 3  

SciTech Connect

Dialkyloxo({eta}{sup 5}pentamethylcyclopentadienyl)rhenium(V) complexes ({eta}{sup 5}-C{sub 5}Me{sub 5})Re({double bond}O)(CH{sub 3})R{prime}(R{prime} = C{sub 2}H{sub 5}, CH{sub 2}Si(CH{sub 3}){sub 3}, CH{sub 2}C(CH{sub 3}){sub 3}), 1c-e, have become accessible through alkylation of ({eta}{sup 5}-C{sub 5}Me{sub 5})Re({double bond}O)(Cl)(CH{sub 3}) (7) with R{prime}MgCl. 1c-e are the first rhenium complexes containing different alkyl ligands. The neopentyl derivative 1e (R{prime} = CH{sub 2}C(CH{sub 3}){sub 3}) crystallizes in the orthorhombic space group Pbca with a = 960.7 (2), b = 2.844.5 (4), c = 1,260.7 (2) pm, and Z = 8. The X-ray crystal structure was refined to R{sub W} = 3.9%. The chiral molecule shows a distorted tetrahedral geometry around the rhenium center. The tribromide 3b has been structurally characterized. Brown crystals of 3b belong to space group P2{sub 1}/c with unit cell dimensions a = 1,311.5 (2), b = 723.0 (1), c = 1,901.6 (2) pm, {beta} = 92.68 (1){degree}, and Z = 4. The structure exhibits a four-legged piano stool geometry with no trans influence of the neopentylidyne ligand to the bromine atom.

Herrmann, W.A.; Felixberger, J.K.; Anwander, R.; Herdtweck, E.; Kiprof, P.; Riede, J. (Anorganisch-chemisches Institut der Technischen Universitaet, Garching bei Muenchen (West Germany))



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

SciTech Connect

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

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



Comparison of Stretching Force Constants in Symmetry Coordinates between Td and C3v Point Groups  

NASA Astrophysics Data System (ADS)

In this paper we consider what happens to the force constants of a silicate moiety (SiO4) when the length of one of its bonds is changed. This situation exists in the molecule O3SiObrSiO3, where Obr is the bridging oxygen atom connecting the two SiO3 moieties. The problem is to present a set of force constants such that when the structure of the more symmetric molecule is perturbed, the relevant force constants are also perturbed. Algebraic expressions are derived for the stretching force constants of SiO4 (tetrahedral point group Td) and ObrSiO3 (point group C3v) in symmetry coordinates. This paper is addressed to students and researchers in applied group theory who wish to compare force constants between similar molecules. We assume the reader has some familarity with the group theoretical methods presented by Wilson et al. (Wilson, E. B. Jr.; Decius, J. C.; Cross, P. C. Molecular Vibrations; Dover: New York, 1980). We cannot apply Wilson's method for obtaining symmetry coordinates from internal coordinates directly, as we demonstrate. Instead we must start with the irreducible representations of the symmetries of the moiety with the higher symmetry and then reduce them to the representations of the symmetries of the moiety with the lower symmetry. The symmetry coordinates are calculated for each species in order to factor the secular equation. The matrix representations of the generators of these point groups are a function of the specific symmetry coordinates. Finally, the symmetry coordinates are applied to the force constant matrix and the algebraic results are compared.

Julian, Maureen M.



Variability of crossreactivity of IgE antibodies to group I and V allergens in eight grass pollen species.  


Crossreactivity to Dactylis glomerata, Festuca rubra, Phleum pratense, Anthoxanthum odoratum, Secale cereale, Zea mays, and Phragmites communis of IgE antibodies against Lol p I or Lol p V was investigated by means of RAST-inhibition. Within a group of sera the degree of crossreactivity was demonstrated to be highly variable. Individual sera were not always equally crossreactive to all pollen species. A high degree of crossreactivity for Group I allergens did not necessarily implicate the same for Group V. Group I and Group V representatives were found to be present in all eight species. It was demonstrated that within this group of grass species significant quantitative and qualitative differences exist, with respect to Group I and Group V allergens. Species with a low phylogenetic affinity to Lolium perenne, like Zea mays and Phragmites communis showed a very low degree of reactivity, even when measured with the most crossreactive sera. A higher taxonomic relationship however, did not always implicate a closer antigenic resemblance. Antigenically both allergens from Zea mays are more similar to Lol p I and Lol p V, than the analogues in Secale cereale. PMID:1382820

Van Ree, R; Driessen, M N; Van Leeuwen, W A; Stapel, S O; Aalberse, R C



Platinum group element concentrations and osmium isotopic composition in urban airborne particles from Boston, Massachusetts.  


Platinum, Pd, Rh, and Os were found to occur at elevated concentrations in airborne particles (PM10) collected at urban sites in Boston, MA. Average Pt, Pd, Rh, and Os concentrations were 6.9 +/- 1.9, 8.1 +/- 1.8, 1.50 +/- 0.50, and 0.068 (-0.068 + 0.070) pg m(-3), respectively. Elevated Pt, Pd, and Rh concentrations are attributed to automobile catalysts, which use Pt, Pd, and Rh for the removal of pollutants from engine exhaust gas. An automobile catalyst source is supported by significant correlations between these elements and by a Pt/Rh similar to that in catalysts. Elevated Os concentrations are also believed to be the result of emission from automobile catalysts in which Os occurs as an impurity. The isotopic composition of Os (187Os/ 188Os) ranged from 0.30 to 2.90, indicating large variations in Os sources. Osmium has a predominantly anthropogenic origin at concentrations > 0.1 pg m(-3), whereas natural sources are more important at lower Os concentrations. Osmium isotopic composition also indicates that Pt, Pd, and Rh in Boston air are of almost exclusive anthropogenic origin, with a relatively small natural contribution. Our results indicate that scavenging by rain plays a major role in the atmospheric residence time and environmental fate of PGE. PMID:16475323

Rauch, Sebastien; Hemond, Harold F; Peucker-Ehrenbrink, Bernhard; Ek, Kristine H; Morrison, Gregory M



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

NASA Astrophysics Data System (ADS)

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

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



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.



Platinum group element abundances in a peat layer associated with the Tunguska event, further evidence for a cosmic origin  

NASA Astrophysics Data System (ADS)

We have measured excesses of Pd, Rh, Ru, REE, Co, Sr, and Y in a peat column from the Northern peat bog of the 1908 Tunguska explosion site. Earlier, in this peat column the presence of an Ir anomaly at the event layers (30- 45 cm depth) has been found (Planet Space Sci. 48 (1998) 179). In these layers, Pd, Rh, Ru, Co, Sr, and Y show pronounced anomalies of a factor 4-7 higher than the background value. In the event layers there are also good correlations between the siderophile platinum group elements (Pd, Rh, Ru) and Co, indicators of cosmic material, which imply they might have the same source, i.e. the Tunguska explosive body. The patterns of CI-chondrite-normalized REE in the event layers are much flatter than those in normal peat layers and different from those in the nearby traps. Furthermore, in these layers the patterns of CI-chondrite-normalized PGEs and the element ratios (e.g. C/Pd, C/Rh, and between some siderophile elements) give evidence that the Tunguska explosive body was more likely a comet, although we cannot exclude the possibility that the impactor could be a carbonaceous asteroid. We have estimated the total mass of a solid component of the explosive body up to 10 3-10 6 tons.

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



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

NASA Astrophysics Data System (ADS)

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

Schmid, H. M.; Schild, H.



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


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

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



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

PubMed Central

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

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



Solid solution softening and hardening in the group-V and group-VI bcc transition metals alloys: First principles calculations and atomistic modeling  

Microsoft Academic Search

The interaction of d transition metal additions with dislocations was studied in bcc alloys by using the atomic row model with ab initio parametrization of the interatomic interactions. Opposite trends were obtained for the solute-dislocation interactions in the group-V (Nb, Ta) and group-VI (Mo, W) bcc metals: while additions with extra valence electrons enhance the double-kink nucleation and result in

N. I. Medvedeva; Yu. N. Gornostyrev; A. J. Freeman



Refractory inclusions from the Leoville, Efremovka, and Vigarano C3V chondrites - Major element differences between Types A and B, and extraordinary refractory siderophile element compositions  

NASA Technical Reports Server (NTRS)

Instrumental neutron activation analysis is used to measure the bulk chemical compositions of ten Ca-, Al-rich inclusions (CAIs) from three C3V chondrites of the reduced subgroup, five from Leoville, three from Efremovka, and two from Vigarano. Six of the inclusions are found to possess very large fractionations between refractory siderophile elements, and four of the six have remarkably high concentrations of these siderophiles, as compared with CAIs analyzed previously. Most of the inclusions analyzed here have lower concentrations of Na, Au, Fe, Zn, and Mn than their Allende counterparts, consistent with the idea that they have experienced secondary alteration at a higher temperature or for a shorter time than did Allende inclusions.

Sylvester, Paul J.; Simon, Steven B.; Grossman, Lawrence



Anti-bactericidal properties of stingray Dasyatis pastinaca groups V, IIA, and IB phospholipases A2: a comparative study.  


Group IIA secreted phospholipase A2 (group IIA sPLA2) is known to display potent Gram-positive bactericidal activity in vitro and in vivo. We have analyzed the bactericidal activity of the full set of native stingray and dromedary groups V, IIA, and IB sPLA2s on several Gram-positive and Gram-negative strains. The rank order potency among both marine and mammal sPLA2s against Gram-positive bacteria is group IIA?>?V?>?IB, whereas Gram-negative bacteria exhibited a much higher resistance. There is a synergic action of the sPLA2 with lysozyme when added to the bacteria culture prior to sPLA2.The bactericidal efficiency of groups V and IIA sPLA2s was shown to be dependent upon the presence of calcium ions and to a less extent Mg(2+) ions and then a correlation could be made to its hydrolytic activity of membrane phospholipids. Importantly, we showed that stingray and dromedary groups V, IIA, and IB sPLA2s present no cytotoxicity after their incubation with MDA-MB-231cells. stingray groups V and IIA sPLA2s, like mammal ones, may be considered as future therapeutic agents against bacterial infections. PMID:25119545

Bacha, Abir Ben



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

PubMed Central

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

Bee, Mark A.; Riemersma, Kasen K.



Phase transitions in Group III-V and II-VI semiconductors at high pressure  

NASA Technical Reports Server (NTRS)

The structures and transition pressures of Group III-V and II-VI semiconductors and of a pseudobinary system (Ga/x/In/1-x/Sb) have been investigated. Results indicate that GaP, InSb, GaSb, GaAs and possible AlP assume Metallic structures at high pressures; a tetragonal, beta-Sn-like structure is adopted by only InSb and GaSb. The rocksalt phase is preferred in InP, InAs, AlSb, ZnO and ZnS. The model of Van Vechten (1973) gives transition pressures which are in good agreement with measured values, but must be refined to account for the occurrence of the ionic rocksalt structure in some compounds. In addition, discrepancies between the theoretical scaling values for volume changes at the semiconductor-to-metal transitions are observed.

Yu, S. C.; Liu, C. Y.; Spain, I. L.; Skelton, E. F.



Platinum-group elemental geochemistry of mafic and ultramafic rocks from the Xigaze ophiolite, southern Tibet  

NASA Astrophysics Data System (ADS)

The Xigaze ophiolite in the central part of the Yarlung-Zangbo suture zone, southern Tibet, has a well-preserved sequence of sheeted dykes, basalts, cumulates and mantle peridotites at Jiding and Luqu. Both the basalts and diabases at Jiding have similar compositions with SiO 2 ranging from 45.9 to 53.5 wt%, MgO from 3.1 to 6.8 wt% and TiO 2 from 0.87 to 1.21 wt%. Their Mg #s [100Mg/(Mg + Fe)] range from 40 to 60, indicating crystallization from relatively evolved magmas. They have LREE-depleted, chondrite-normalized REE diagrams, suggesting a depleted mantle source. These basaltic rocks have slightly negative Nb- and Ti-anomalies, suggesting that the Xigaze ophiolite represents a fragment of mature MORB lithosphere modified in a suprasubduction zone environment. The mantle peridotites at Luqu are high depleted with low CaO (0.3-1.2 wt%) and Al 2O 3 (0.04-0.42 wt%). They display V-shaped, chondrite-normalized REE patterns with (La/Gd) N ratios ranging from 3.17 to 64.6 and (Gd/Yb) N from 0.02 to 0.20, features reflecting secondary metasomatism by melts derived from the underlying subducted slab. Thus, the geochemistry of both the basaltic rocks and mantle peridotites suggests that the Xigaze ophiolite formed in a suprasubduction zone. Both the diabases and basalts have Pd/Ir ratios ranging from 7 to 77, similar to MORB. However, they have very low PGE abundances, closely approximating the predicted concentration in a silicate melt that has fully equilibrated with a fractionated immiscible sulfide melt, indicating that the rocks originated from magmas that were S-saturated before eruption. Moderate degrees of partial melting and early precipitation of PGE alloys explain their high Pd/Ir ratios and negative Pt-anomalies. The mantle peridotites contain variable amounts of Pd (5.99-13.5 ppb) and Pt (7.92-20.5 ppb), and have a relatively narrow range of Ir (3.47-5.01 ppb). In the mantle-normalized Ni, PGE, Au and Cu diagram, they are relatively rich in Pd and depleted in Cu. There is a positive correlation between CaO and Pd. The Pd enrichment is possibly due to secondary enrichment by metasomatism. Al 2O 3 and Hf do not correlate with Ir, but show positive variations with Pt, Pd and Au, indicating that some noble metals can be enriched by metasomatic fluids or melts carrying a little Al and Hf. We propose a model in which the low PGE contents and high Pd/Ir ratios of the basaltic rocks reflect precipitation of sulfides and moderate degrees of partial melting. The high Pd mantle peridotites of Xigaze ophiolites were formed by secondary metasomatism by a boninitic melt above a subduction zone.

Chen, Genwen; Xia, Bin



Potential-model calculation of an order-v^2 NRQCD matrix element  

E-print Network

We present two methods for computing dimensionally-regulated NRQCD 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/psi state that appears in the leading relativistic correction to the production and decay of that state through the color-singlet quark-antiquark channel.

Geoffrey T. Bodwin; Daekyoung Kang; Jungil Lee




E-print Network

. The aim is to identify the liquid/solid interface and estimate the field temperature in the welded parts of plate (see fig. 1), is defined by Figure 1. The solid part of the welded workpiece with interface of complex thermo-fluid phenomena that occur in welding processes. The linear finite elements dicretization

Paris-Sud XI, Université de


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


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

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



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.



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

NASA Astrophysics Data System (ADS)

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

Mungall, James E.; Brenan, James M.



A Simulation Study on Optimal Design Parameters of 200V Class Induction Range using Finite Element Method  

NASA Astrophysics Data System (ADS)

Induction heating has found a new feasibility in domestic appliances. Its application is known as an “induction range” or an “induction heating oven”. Conventional design schemes of them have depended on the experience and insight of designers. In the paper, the authors treat it as an electromagnetic device to investigate the mechanism of power dissipation using the Finite Element Method, where an impressed voltage supply is taken account of and the constant V/f condition is imposed for the constant impressed magnetic flux. Furthermore the authors will examine how to heat an aluminum pan and discuss the optimal frequency of a power supply.

Ohchi, Masashi; Furukawa, Tatsuya


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



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

NASA Technical Reports Server (NTRS)

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

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



Potential-model calculation of an order-v^2 NRQCD matrix element  

E-print Network

We present two methods for computing dimensionally regulated NRQCD 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. The second method is more direct and yields higher numerical accuracy, but is limited to use in potential models. It requires knowledge of the wave function, the binding energy, and the potential. We apply these methods to the Cornell potential model and compute a matrix element for the J/psi state that appears in the leading relativistic correction to the production and decay of that state through the color-singlet quark-antiquark channel.

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



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

NASA Technical Reports Server (NTRS)

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

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



A 0.8 nV\\/?Hz CMOS preamplifier for magneto-resistive read elements  

Microsoft Academic Search

State-of-the-art tape drives now employ MR heads to achieve increased bit density and speed-independent signal amplitude. In such systems, the preamplifier (PA) has to support simultaneous reading of up to four signals from up to eight magneto-resistive (MR) read elements. Hence, thermal considerations require a minimum power consumption architecture. Due to manufacturing and wear out, head impedances from 20 to

M. E. Robinson; H. W. Klein; S. Palla; T.-S. Chung



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

PubMed Central

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

Arakere, Gayathri



Molecules as Segmented Storage Elements in Floating Gate Memories................................................................................................MAT.1 In-situ Deposition of High-k Dielectrics on a III-V Compound Semiconductor .............  

E-print Network

Materials Molecules as Segmented Storage Elements in Floating Gate MemoriesAls NANOTeCHNOlOGY Molecules as segmented storage elements in Floating Gate Memories S. Paydavosi, V. Bulovi Sponsorship: SRC/FCRP MSD Conventional flash memories may reach fundamental scaling limits [1] because

Reif, Rafael


Regulation of Delayed Prostaglandin Production in Activated P388D1 Macrophages by Group IV Cytosolic and Group V Secretory  

E-print Network

mobilization and prostaglandin E2 (PGE2) production in the macrophage-like cell line P388D1. When a new cloneRegulation of Delayed Prostaglandin Production in Activated P388D1 Macrophages by Group IV of prostaglandins by major immunoinflammatory cells such as macrophages and mast cells usually occur in two phases

Dennis, Edward A.


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

E-print Network

performed [16, 17] since PbO is used now in the experiment on search for the electron EDM by the group of D. DeMille. Recently, a new scheme for the electron EDM search on the HI+ molecular ion was sug- gested by R. Stutz and E. Cornell. As our extensive calcu- lations of electron EDM enhancement factor showed

Titov, Anatoly



NSDL National Science Digital Library

This interactive Flash applet models the measurement interpretation of division. A child or teacher chooses a total number of objects and a divisor representing the size of equal groups. The applet allows the user to move the objects into equal groups and links the process to jumps on a number line. The applet can be used to introduce children to remainders and to reinforce the language and notation of division. It works well on an interactive white board or projector. A teacher's guide to this collection of applets is cataloged separately.



Platinum-group elements in the Eastern Deccan volcanic province and a comparison with platinum metals of the western Deccan  

NASA Astrophysics Data System (ADS)

This study is the first detailed investigation of the platinum-group elements (PGE) at the eastern margin of the Deccan volcanic province of India. One of the PGE, osmium, is not included largely because of analytical problems. The study is focused on mafic volcanics and dykes from four areas including Amarkantak, Umaria, Shahdol and Chirimiri. The first two localities represent two lava piles of about 170 and 400 m thickness respectively. In Umaria, 16 flows have been demarcated based on petrography and field studies. The Shahdol samples are basal lava formations overlying Gondwana sediments (Carboniferous) and the Chirimiri samples are dykes. In this study, the western Deccan province is defined as the Western Ghats plus Kutch. On average, the PGE are ~20% higher in Amarkantak than Umaria and the flows are ~13% higher in PGE than the dykes. A Zr vs. Pd scattergram found a strong positive correlation for these two elements except for one Umaria sample which indicated severe Pd loss. A comparison of west and east parts of the Deccan volcanic province using primitive mantle normalization showed that higher values prevailed in the western province suite in the Ni-Ir-Ru-Pt region. In contrast, eastern province values dominated in the Pd-Au-Cu region at the `Cu' end of the profiles. A strong dominance of Pd in the eastern Deccan was also of interest. A number of factors, for example, percentage partial melting of the source rock and the temperature and pressure of partial melting strongly influence the character of these profiles. The observed PGE profile characteristics probably result in part from a long distance of subsurface transport of Deccan magma from the western to eastern regions.

Crocket, James; Paul, Dalim; Lala, Trisha



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


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

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



L x-ray production in lanthanide elements by 1 - 5 MeV helium ions  

Microsoft Academic Search

L x-ray production in 0953-4075\\/30\\/24\\/016\\/img10 and 0953-4075\\/30\\/24\\/016\\/img11 was measured for 0953-4075\\/30\\/24\\/016\\/img12 bombardment in the energy range 1 - 5 MeV. Very thin target foils were used, and x-ray yields were measured simultaneously with elastically scattered ions. The L-shell and individual 0953-4075\\/30\\/24\\/016\\/img13 and 0953-4075\\/30\\/24\\/016\\/img14 production cross sections and their ratios were extracted. These cross sections are compared to the results of

Y. C. Yu; C. W. Wang; E. K. Lin; T. Y. Liu; H. L. Sun; J. W. Chiou; G. Lapicki



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

E-print Network

? - Subgroup 3 7: Specky A, Mainland? - Subgroup 4 8: Specky A, Miscellaneous Aegean seals: stylistic groups 16 17 Fig.2 9-12: Specky A, Miscellaneous (cont.) 13-16: Specky B 17: Specky C 123 a7 124 John G. Younger 22 _'b' " l8-26: Specky C (cont.) 23 Aegean...) Goats: VII 93 (1), CS 286 from Goulas, and 287 ,iIt 4.122 (2) from SellopouloT. 2. Close: a) Y 216, the agrimi kid, from Armenoi r. 15 (LM III B; the rion is in specky c, berow), and CS 3P from Palaikastro. b) cylinder vrr 17J from Golgoi, cyprus (for a...

Younger, John G.



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

NASA Astrophysics Data System (ADS)

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

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



Enzymatic properties of stingray Dasyatis pastinaca group V, IIA and IB phospholipases A(2): a comparative study.  


In the present study, we have purified the group V phospholipase from the heart of cartilaginous fish stingray Dasyatis pastinaca and compared its biochemical properties with group IIA (sPLA2-IIA) and IB (sPLA2-IB) phospholipases previously purified from pancreas and intestine, respectively. Group V phospholipase (sPLA2-V) was purified to homogeneity by heat treatment, ammonium sulphate precipitation and RP-HPLC. The N-terminal sequence of the purified sPLA2-V exhibits a high degree of homology with those of mammal. The enzyme was found to be monomeric with a molecular mass estimation of 14 kDa. The specific activity of the purified enzyme, measured at pH 8 and 37 °C was 52 U/mg. Like sPLA2-IB and sPLA2-IIA, the sPLA2-V is found to be stable between pH 3 and 11 after 30 min of incubation. The purified sPLA2-V retained 65% of its activity after 10 min of incubation at 70 °C and it absolutely requires Ca(2+) for enzymatic activity. In addition it displayed high tolerance to organic solvents. Kinetic parameters Kmapp, kcat and the deduced catalytic efficiency (kcat/Kmapp) of the purified group-V, -IB and -IIA PLA2s were determined using phosphatidylethanolamine (PE), phosphatidylcholine (PC) or phosphatidylserine (PS) as substrate. The three enzymes hydrolyze the zwiterionic PE and PC substrates more efficiently than anionic PS substrate. PMID:24120965

Ben Bacha, Abir; Abid, Islem; Horchani, Habib; Mejdoub, Hafedh



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

NASA Astrophysics Data System (ADS)

We present new measurements of 186Os/188Os and 187Os/188Os in 10 Os-rich platinum group element (PGE) alloys from placer deposits formed by the mechanical erosion of peridotite-bearing ophiolites in the Klamath and Siskiyou Mountains in northern California and southwestern Oregon. These data nearly double our database of high-precision 186Os/188Os measurements on such samples. Together with previously published data, our new results reinforce the conclusion that the radiogenic 186Os/188Os compositions of these PGE alloys are very difficult to reconcile with a derivation of their Os from the outer core. Such a model requires extremely early growth of the inner core to its present size, within several hundred million years after accretion of the Earth, which is geophysically implausible. Collectively, our data suggest instead that partial melting or metasomatic processes in the upper mantle play a primary role in controlling the Os isotopic systematics of these Os-rich PGE alloys and suggest the existence of upper mantle components characterized by radiogenic 186Os/188Os ratios. Pyroxene-rich lithologies are possible candidates.

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



5' untranslated sequences modulate rapid mRNA degradation mediated by 3' AU-rich element in v-/c-fos recombinants.  

PubMed Central

One major determinant of rapid mRNA decay is the presence of AU-rich sequences located in 3' untranslated regions (UTR). To assess for the contribution of upstream sequences on the activity of the 3' AU-rich destabilizing element, we have determined the decay-rates of v-/c-fos hybrid transcripts by quantitative RNA protection analysis. In a transient expression assay, v-/c-fos recombinants generated two mRNA populations via alternative splicing and removal of an optional intron entirely located in the 5' UTR. Both mRNA species were found to be relatively stable in constructs lacking the c-fos AU-rich destabilizing element. Unexpectedly, in recombinants where intrinsic AU sequences were kept intact, only the full-length mRNA population showed high instability whereas the spliced mRNA species remained relatively stable. A v-/c-fos 5' UTR fragment encoding the optional intron was inserted into alpha-globin genes harboring either the c-fos or GM-CSF destabilizing element. The splicing and degradation patterns of these heterologous transcripts paralleled that of v-/c-fos recombinants. These observations unmasked a 5' cis-acting element in v-/c-fos mRNA whose presence is required for the activity of the AU-rich destabilizing element. They demonstrate the important role of interactions between distinct sequences on the regulation of mRNA stability. Images PMID:1454537

Roy, N; Laflamme, G; Raymond, V



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.



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



Molecular structure and intermediate phases in group-V binary chalcogenide glasses  

NASA Astrophysics Data System (ADS)

Chalcogenide glasses offer unique opportunities for basic science and technological applications. The physical properties of such network-forming glasses, including the glass-forming tendency, are intimately connected to global connectivity of their backbones. In particular, the elastic behavior of glasses leads to the existence of three distinct phases that appears to be generic in network forming systems. Weakly cross-linked networks are mechanically soft and form floppy phases. Optimally cross-linked networks lead to stress-free or self-organized networks, and are identified with intermediate phases. Strongly cross-linked networks are mechanically stiff and usually form part of stressed-rigid phases. The floppy-intermediate and stressed-rigid classification of the group V chalcogenides is recognized in this work for the first time. The glass systems examined include P-Se, As-Se, and As-S. Thermally reversing windows (glass compositions wherein Tg become almost completely reversing) are observed in the three binary glass systems using temperature-Modulated Differential Scanning Calorimetry (MDSC), and are identified with the opening of (non-mean-field) intermediate phases . The molecular structure of these glasses is studied by Raman scattering, MDSC and 31P NMR, and the local structures responsible for intermediate phases are identified with assistance from constraint counting procedures. Raman scattering and Nuclear Magnetic Resonance (NMR) results on P-Se glasses provide compelling evidence for existence of four-fold coordinated phosphorous species that are bonded to three bridging and one terminal selenium, Se = P(Se1/2)3. The structure results provide a basis to quantitatively understand compositional trends in Tg in the stochastic agglomeration limit. The existence of analog four-fold coordinated As species is suggested by MDSC experiments on As-Se glasses. Our experimental results also show that stressed-rigid phases in the examined glasses are usually phase separated on a molecular level. Phase separation initiates near the stoichiometric composition, As2S3, and grows as the As content, x, of binary As xS1-x glasses exceeds 0.38. Similar behavior has been observed in As-Se and P-Se glasses. A new understanding of global maxima in glass transition temperatures near stoichiometric compositions has emerged. These maxima are the result of a decrease in network connectivity as the backbone nano-scale phase separates.

Georgiev, Daniel Georgiev


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. PMID:16908861

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



Petrogenesis of Ophiolitic Chromitites from the Southeastern Turkey: Chromite Composition and Geochemistry and Mineralogy of Platinum Group Elements  

NASA Astrophysics Data System (ADS)

Ophiolitic chromitites from the southeastern Turkey are located within mostly mantle peridotites (harzburgite and dunite) in the form of veinlets and lenticular bodies. Chromitites show a wide range of composition in terms of Cr# (39-82) and Mg# (45-75). Platinum group element (PGE) concentrations in whole rock range between 42 and 348 ppb (mean 135 ppb) in most of the investigated samples. High-Cr chromitites (Cr# > 70; Mg# = 45-67) are represented by low content of TiO2 (?0.2 %wt.) and higher content of total PGE (mean 158 ppb), whereas low-Cr ones (Cr# < 70; Mg# = 57-75) contain higher TiO2 contents (0.2-0.4 %wt.) and are represented by lower content of total PGE (mean 84 ppb). However, two chromitite samples show significant enrichments of especially IPGE (Os, Ir, Ru) with total PGE contents reaching up to 1.1 and 2.7 ppm, respectively. The investigated ophiolitic chromitites contain primary inclusions of platinum group minerals (PGM), base metal minerals (BMM) and silicates. The Cr-rich chromitites were observed to contain various type of PGM (up to 10 microns in size) of which the laurite is the most abundant type, accompanied by few irarsite and Os-Ir alloys. Single or poly-phase laurite inclusions, associated with hydrous silicate of amphibole in most cases, are rich in Ru [Ru#; 100×Ru/(Ru+Os) = 61-80]. Millerite is the most abundant base metal mineral in chromite grains. Pentlandite, polydimite, heazlewoodite, violarite and rarely pyrite are observed as the others BMMs. Olivine, amphibole, clinopyroxene, orthopyroxene have been also identified as primary inclusions. PGM and BMM mineralogy suggest that the chromites started to crystallize at high temperature (~1300oC) and low ƒS2 conditions, and followed to lower temperature (1000oC) and higher ƒS2 conditions. Chemical and mineralogical data from the southeastern Turkey ophiolitic chromitites and their inclusions indicate that the high-Cr chromitites were crystallized out of boninitic melt in a island arc environment, whereas chromitites of high-Al composition were thought to crystallize either from the MORB type melt in middle oceanic ridge setting or back-arc environment.

Melih Akmaz, Recep; Uysal, Ibrahim; Saka, Samet



Re-Os isotope and platinum group elements of a FOcal ZOne mantle source, Louisville Seamounts Chain, Pacific ocean  

NASA Astrophysics Data System (ADS)

The Louisville Seamount Chain (LSC) is, besides the Hawaiian-Emperor Chain, one of the longest-lived hotspot traces. We report here the first Re-Os isotope and platinum group element (PGE) data for Canopus, Rigil, and Burton Guyots along the chain, which were drilled during IODP Expedition 330. The LSC basalts possess (187Os/188Os)i = 0.1245-0.1314 that are remarkably homogeneous and do not vary with age. A Re-Os isochron age of 64.9 ± 3.2 Ma was obtained for Burton seamount (the youngest of the three seamounts drilled), consistent with 40Ar-39Ar data. Isochron-derived initial 187Os/188Os ratio of 0.1272 ± 0.0008, together with data for olivines (0.1271-0.1275), are within the estimated primitive mantle values. This (187Os/188Os)i range is similar to those of Rarotonga (0.124-0.139) and Samoan shield (0.1276-0.1313) basalts and lower than those of Cook-Austral (0.136-0.155) and Hawaiian shield (0.1283-0.1578) basalts, suggesting little or no recycled component in the LSC mantle source. The PGE data of LSC basalts are distinct from those of oceanic lower crust. Variation in PGE patterns can be largely explained by different low degrees of melting under sulfide-saturated conditions of the same relatively fertile mantle source, consistent with their primitive mantle-like Os and primordial Ne isotope signatures. The PGE patterns and the low 187Os/188Os composition of LSC basalts contrast with those of Ontong Java Plateau (OJP) tholeiites. We conclude that the Re-Os isotope and PGE composition of LSC basalts reflect a relatively pure deep-sourced common mantle sampled by some ocean island basalts but is not discernible in the composition of OJP tholeiites.

Tejada, Maria Luisa G.; Hanyu, Takeshi; Ishikawa, Akira; Senda, Ryoko; Suzuki, Katsuhiko; Fitton, Godfrey; Williams, Rebecca



Examining the Use of Video Study Groups for Developing Literacy Pedagogical Content Knowledge of Critical Elements of Strategy Instruction with Elementary Teachers  

ERIC Educational Resources Information Center

This collective case study explored what nine elementary teachers' video study group discussions revealed about their understanding of pedagogical content knowledge for an explicit reading strategy instruction framework, Critical Elements of Strategy Instruction (CESI). Qualitative methods were used to inductively and deductively analyze…

Shanahan, Lynn E.; Tochelli, Andrea L.



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

Technology Transfer Automated Retrieval System (TEKTRAN)

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


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

Microsoft Academic Search

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

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



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

Microsoft Academic Search

This work presents an application of probabilistic neural networks to map the potential for platinum group elements (PGE) mineralization sites in the northeast portion of the Carajás Mineral Province (CMP), Brazilian Amazon. Geological and geophysical gamma-spectrometric and magnetic data were used to generate evidential maps to derive input feature vectors. Feature vectors representing known mineralized locations were used as training

Emilson Pereira Leite; Carlos Roberto de Souza Filho



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. PMID:23682154

Rius, Nuria; Delprat, Alejandra; Ruiz, Alfredo



Expression of ABO blood-group genes is dependent upon an erythroid cell-specific regulatory element that is deleted in persons with the B(m) phenotype.  


The ABO blood group is of great importance in blood transfusion and organ transplantation. However, the mechanisms regulating human ABO gene expression remain obscure. On the basis of DNase I-hypersensitive sites in and upstream of ABO in K562 cells, in the present study, we prepared reporter plasmid constructs including these sites. Subsequent luciferase assays indicated a novel positive regulatory element in intron 1. This element was shown to enhance ABO promoter activity in an erythroid cell-specific manner. Electrophoretic mobility-shift assays demonstrated that it bound to the tissue-restricted transcription factor GATA-1. Mutation of the GATA motifs to abrogate binding of this factor reduced the regulatory activity of the element. Therefore, GATA-1 appears to be involved in the cell-specific activity of the element. Furthermore, we found that a partial deletion in intron 1 involving the element was associated with B(m) phenotypes. Therefore, it is plausible that deletion of the erythroid cell-specific regulatory element could down-regulate transcription in the B(m) allele, leading to reduction of B-antigen expression in cells of erythroid lineage, but not in mucus-secreting cells. These results support the contention that the enhancer-like element in intron 1 of ABO has a significant function in erythroid cells. PMID:22408256

Sano, Rie; Nakajima, Tamiko; Takahashi, Keiko; Kubo, Rieko; Kominato, Yoshihiko; Tsukada, Junichi; Takeshita, Haruo; Yasuda, Toshihiro; Ito, Kazuto; Maruhashi, Takayuki; Yokohama, Akihiko; Isa, Kazumi; Ogasawara, Kenichi; Uchikawa, Makoto



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

SciTech Connect

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

Anderson, T.J.



Sniffing for Clues to the Dinosaurs Demise: Measurement of Osmium Isotope Compositions and Platinum Group Element Abundances in Volcanic Emissions  

NASA Astrophysics Data System (ADS)

Platinum Group Elements (PGE: Os, Ir, Rh, Ru, Pt, Pd) and osmium isotopes measured in marine and terrestrial sediment, snow and ice records are important paleo-tracers of riverine, hydrothermal, extraterrestrial, volcanic and anthropogenic inputs into the global surficial environment. For instance, the marine Os isotope record across the Cretaceous-Tertiary Boundary (KTB) indicates that the onset of the main phase of Deccan volcanism and the transient late Maastrichtian warming preceded the large extraterrestrial impact and the related KTB mass extinction by several hundred thousand years [Ravizza and Peucker-Ehrenbrink, 2003]. Distinguishing extraterrestrial from volcanic PGE sources has been difficult due to the similarity in Os isotopic compositions, complex PGE fractionations, and our lack of knowledge of the Os isotopic composition and PGE abundances in volcanic aerosols. These difficulties have fueled vigorous debate about extraterrestrial vs. volcanic triggers of mass extinctions in the geologic record. To assess the volcanic contribution to the global Re-Os-PGE cycle we have initiated a study of Os isotopic compositions and PGE abundances in volcanic emissions from volcanoes around the globe. Here we report preliminary data on PGE abundances and Os isotopes measured in gas and aerosol filter samples from Vulcan Masaya, Nicaragua and Mt Etna, Italy. Samples were analyzed by ID-ICPMS (ThermoFinnigan ELEMENT 2 and NEPTUNE) at the Woods Hole Oceanographic Institution. Osmium isotope compositions of the filters are unradiogenic (0.1272 to 0.187). Osmium concentrations range from 28 to 97 pg/cubic meter and are 3-4 orders of magnitude lower than those measured by Krahenbuhl et al. [1992] during the spring 1984 eruption of Mauna Loa just after the lava fountaining phase. Normalized PGE abundance patterns are fractionated relative to carbonaceous chondrites and two important features distinguish the pattern from other important PGE sources: 1) Os/Ir is much higher than that of the continental crust, the mantle and extraterrestrial matter; and 2) Pt/Pd is much lower than that of the continental crust, mantle, extraterrestrial matter and catalytic converters. If these PGE patterns from Masaya and Etna are typical of volcanic emissions worldwide they indicate that volcanic emission PGE patterns are distinct from the globally integrated KTB patterns [Tredoux et al. 1989; Evans et al., 1993] and that a volcanic source is not the cause of the elevated PGE abundances across the KTB. The PGE pattern of volcanic emissions is also different from catalytic converters enabling us to distinguish between volcanic sources and contamination from catalytic converters in places such as the Greenland Ice sheet [Barbante et al., 2001]. While these data have important implications for understanding the contribution of volcanic emissions to the global Re-Os-PGE cycles they need to be augmented with further analyses from other volcanoes.

Sims, K. W.; Peucker-Ehrenbrink, B.; Mather, T.; Pyle, D.; Martin, R.; Gauthier, P.; Aiuppa, A.



Atomic K shell ionization by 3.0-15 MeV oxygen ions for selected elements between Ti and In  

Microsoft Academic Search

The K-shell X-rays and elastic scattering particles induced by 3.0-15 MeV oxygen ions were measured simultaneously for selected elements between Ti and In (in the atomic number range Z = 22-49). Experimental K X-ray production cross sections as a function of projectile energy in this energy interval in steps of 0.6 MeV are reported. Results of measurement are compared with

C. W. Wang; E. K. Lin; Y. C. Yu



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,



Differential occurrence of chromosome inversion polymorphisms among Muller's elements in three species of the tripunctata group of Drosophila, including a species with fast chromosomal evolution.  


Detailed chromosome maps with reliable homologies among chromosomes of different species are the first step to study the evolution of the genetic architecture in any set of species. Here, we present detailed photo maps of the polytene chromosomes of three closely related species of the tripunctata group (subgenus Drosophila): Drosophila mediopunctata, D. roehrae, and D. unipunctata. We identified Muller's elements in each species, using FISH, establishing reliable chromosome homologies among species and D. melanogaster. The simultaneous analysis of chromosome inversions revealed a distribution pattern for the inversion polymorphisms among Muller's elements in the three species. Element E is the most polymorphic, with many inversions in each species. Element C follows; while the least polymorphic elements are B and D. While interesting, it remains to be determined how general this pattern is among species of the tripunctata group. Despite previous studies showing that D. mediopunctata and D. unipunctata are phylogenetically closer to each other than to D. roehrae, D. unipunctata shows rare karyotypic changes. It has two chromosome fusions: an additional heterochromatic chromosome pair and a pericentric inversion in the X chromosome. This especial conformation suggests a fast chromosomal evolution that deserves further study. PMID:23379335

Brianti, Mitsue T; Ananina, Galina; Klaczko, Louis B



Ni, Cu, Au, and platinum-group element contents of sulphides associated with intraplate magmatism: A synthesis  

USGS Publications Warehouse

The tectonic setting of intraplate magmas, typically a plume intersecting a rift, is ideal for the development of Ni - Cu - platinum-group element-bearing sulphides. The plume transports metal-rich magmas close to the mantle - crust boundary. The interaction of the rift and plume permits rapid transport of the magma into the crust, thus ensuring that no sulphides are lost from the magma en route to the crust. The rift may contain sediments which could provide the sulphur necessary to bring about sulphide saturation in the magmas. The plume provides large volumes of mafic magma; thus any sulphides that form can collect metals from a large volume of magma and consequently the sulphides will be metal rich. The large volume of magma provides sufficient heat to release large quantities of S from the crust, thus providing sufficient S to form a large sulphide deposit. The composition of the sulphides varies on a number of scales: (i) there is a variation between geographic areas, in which sulphides from the Noril'sk - Talnakh area are the richest in metals and those from the Muskox intrusion are poorest in metals; (ii) there is a variation between textural types of sulphides, in which disseminated sulphides are generally richer in metals than the associated massive and matrix sulphides; and (iii) the massive and matrix sulphides show a much wider range of compositions than the disseminated sulphides, and on the basis of their Ni/Cu ratio the massive and matrix sulphides can be divided into Cu rich and Fe rich. The Cu-rich sulphides are also enriched in Pt, Pd, and Au; in contrast, the Fe-rich sulphides are enriched in Fe, Os, Ir, Ru, and Rh. Nickel concentrations are similar in both. Differences in the composition between the sulphides from different areas may be attributed to a combination of differences in composition of the silicate magma from which the sulphides segregated and differences in the ratio of silicate to sulphide liquid (R factors). The higher metal content of the disseminated sulphides relative to the massive and matrix sulphides may be due to the fact that the disseminated sulphides equilibrated with a larger volume of magma than massive and matrix sulphides. The difference in composition between the Cu- and Fe-rich sulphides may be the result of the fractional crystallization of monosulphide solid solution from a sulphide liquid, with the Cu-rich sulphides representing the liquid and the Fe-rich sulphides representing the cumulate.

Barnes, S.-J.; Zientek, M.L.; Severson, M.J.



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

USGS Publications Warehouse

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

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



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

NASA Astrophysics Data System (ADS)

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

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



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

NASA Astrophysics Data System (ADS)

Superconducting transition is well known for the Chevrel phases M xMo6S8 and MxMo6Se 8 where M is dopant metal such as Pb, In, Tl and La. Not many ternary group 5 transition metal chalcogenides of similar composition, however, are known to be superconductors. The synthesis and observation of superconducting transition of the Ba doped compound BaxV6S8 (x = 0.45--0.48) is discussed. The electronic structure was analyzed using the tight-binding extended Huckel method. Results of Raman-scattering experiments are also discussed. BaGa4 possesses the most popular structure type in solid state chemistry. More than 600 compounds crystallize in this structure. Many compounds of this family exhibit interesting physical properties such as superconductivity, unusual magnetic behavior, valence fluctuation and heavy fermion phenomena. However, little had been reported about the physical properties of BaGa 4 itself. The single crystal growth, structural characterization, computational his, conductivity and AC susceptibility of crystalline BaGa4 is described. V-Ga binary system is of great interest because some compounds in this family are superconductors exhibiting high critical currents and fields. V 2Ga5 has been reported to show a superconducting transition from 2.1 K to 4.2 K,2,6 depending on the preparation procedure and sample quality. However, no single-crystal X-ray structure determination has been reported for this compound, and the full characterization of its superconducting transition has yet to be completed. The single crystal growth, structural determination, and computational study of Ga5V 2 are discussed. Resistivity and magnetization measurement results are also presented. Ternary intermetallic solid-state compounds of lanthanum, transition metal, and germanium have a wide range of technological applications (i.e., rechargeable cells) because of their interesting physical properties. Many compounds of this type with the stoichiometry LnxTyGe z (Ln = lanthanide, T = transition metal) have been synthesized. A few of them crystallize in orthorhombic lattices in which a transition metal forms a square lattice with capping germanium atoms on the square hollows. This structural motif is found in one of the most populous families, the ThCr 2Si2 series that has more than 600 members. LaNiGe2 , is similar in structure with capped square nets. However, there is one very important difference. In this structure, it is the more electronegative element Ge that builds the square lattice. The main structural motif is the NiGe4 pyramid. With computational analysis as the means of exploration, the electronic charge distribution resulting from such a structural arrangement and the changes that occur to this electronic charge distribution when a partial substitution of Si is made to the Ge in the square lattice are described. Two partially substituted compounds with different levels of Si substitution were synthesized. Their synthesis and magnetic susceptibility measurements are also discussed.

Lobring, Kim Carl


Theoretical study on the relationship between diradical character and second hyperpolarizabilities of four-membered-ring diradicals involving heavy main-group elements.  


By using spin-unrestricted density functional theory methods, the relationship between the diradical character y and the second hyperpolarizability ? (the third-order nonlinear optical (NLO) properties at the molecular scale) for four-membered-ring diradical compounds, that is, cyclobutane-1,3-diyl, Niecke-type diradicals, and Bertrand-type diradicals, were investigated by focusing on the substitution effects of heavy main-group elements as well as of donor/acceptor groups on the y and ? values. It has been found that i)?? is enhanced in the intermediate y region for these four-membered-ring diradicals, ii)?Niecke-type diradicals with intermediate y values, which are realized by tuning the combination of the main-group elements involved, exhibit larger ? values than Bertrand-type diradicals, and iii)?the y value and thus ? value can be controlled by modifying the both-end donor/acceptor substituents attached to carbon atoms in Nicke-type C2 P2 diradicals. These results demonstrate that four-membered-ring diradicals involving heavy main-group elements exhibit high controllability of the y and ?, which indicates the potential applications of four-membered-ring diradicals as a building block of highly efficient open-shell NLO materials. PMID:25428227

Matsui, Hiroshi; Fukuda, Kotaro; Takamuku, Shota; Sekiguchi, Akira; Nakano, Masayoshi



Tables of X-ray mass attenuation coefficients and mass energy-absorption coefficients 1 keV to 20 MeV for elements Z=1 to 92 and 48 additional substances of dosimetric interest  

Microsoft Academic Search

Tables and graphs of the photon mass attenuation coefficient mu\\/rho and the mass energy-absorption coefficient mu(en)\\/rho are presented for all of the elements Z=1 to 92, and for 48 compounds and mixtures of radiological interest. The tables cover energies of the photon (x ray, gamma ray, bremsstrahlung) from 1 keV to 20 MeV. The mu\\/rho values are taken from the

J. H. Hubbell; Stephen M Seltzer



A Human Right to Group Self-Identification?: Reflections on Nixon v. Vancouver Rape Relief  

Microsoft Academic Search

Résumé: Dans Nixon c. Vancouver Rape Relief Society, la Cour d’appel de Colombie-Britannique a maintenu le droit d’un groupe de féministes de s’identifier de façon à exclure les personnes qui n’avaient pas expérimenté le fait d’être traitées comme des filles ou des femmes. Le présent article contribue au débat en cours sur les limites de l’auto-identification d’un groupe en étudiant

Christine Boyle



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

NASA Astrophysics Data System (ADS)

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

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



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


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

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



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

USGS Publications Warehouse

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

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



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


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

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



Symmetry in Nonlinear Mathematical Physics 1997, V.1, 164171. Group Analysis of Ordinary Differential  

E-print Network

ordinary differential equation (ODE-n, n > 2) with r symmetries (r > 1). These strategies were proposed we have an n-th order ordinary differential equation (ODE-n, n > 2) y(n) = x, y, y , . . . , y(n-1 by RFBR, the grant 96­01­01997. #12;Group Analysis of Ordinary Differential Equations of the Order n > 2

Popovych, Roman


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


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

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



Report of the IAU/IAG/COSPAR Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites - 1991  

NASA Technical Reports Server (NTRS)

Revised values are presented for the directions of the north poles of rotation, the prime meridians, and for the sizes and shapes of the planets and satellites. Also presented are definitions of rotational elements and the cartographic coordinate systems. These revised values and definitions are the results of a report provided every three years by an international working group with members from IAU, IAG, and COSPAR.

Davies, M. E.; Abalakin, V. K.; Brahic, A.; Bursa, M.; Chovitz, B. H.; Lieske, J. H.; Seidelmann, P. K.; Sinclair, A. T.; Tiuflin, I. S.



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

Microsoft Academic Search

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

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


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

Microsoft Academic Search

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

J. J. Hanley



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

PubMed Central

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

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



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

Microsoft Academic Search

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)

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



Isolation of a novel IS3 group insertion element and construction of an integration vector for Lactobacillus spp.  

PubMed Central

An insertion sequence (IS) element from Lactobacillus johnsonii was isolated, characterized, and exploited to construct an IS-based integration vector. L. johnsonii NCK61, a high-frequency conjugal donor of bacteriocin production (Laf+) and immunity (Lafr), was transformed to erythromycin resistance (Emr) with the shuttle vector pSA3. The NCK61 conjugative functions were used to mobilize pSA3 into a Laf- Lafs EMs recipient. DNA from the Emr transconjugants transformed into Escherichia coli MC1061 yielded a resolution plasmid with the same size as that of pSA3 with a 1.5-kb insertion. The gram-positive replication region of the resolution plasmid was removed to generate a pSA3-based suicide vector (pTRK327) bearing the 1.5-kb insert of Lactobacillus origin. Plasmid pTRK327 inserted randomly into the chromosomes of both Lactobacillus gasseri ATCC 33323 and VPI 11759. No homology was detected between plasmid and total host DNAs, suggesting a Rec-independent insertion. The DNA sequence of the 1.5-kb region revealed the characteristics of an IS element (designated IS1223): a length of 1,492 bp; flanking, 25-bp, imperfect inverted repeats; and two overlapping open reading frames (ORFs). Sequence comparisons revealed 71.1% similarity, including 35.7% identity, between the deduced ORFB protein of the E. coli IS element IS150 and the putative ORFB protein encoded by the Lactobacillus IS element. A putative frameshift site was detected between the overlapping ORFs of the Lactobacillus IS element. It is proposed that, similar to IS150, IS1223 produces an active transposase via translational frameshifting between two tandem, overlapping ORFs. Images PMID:8071209

Walker, D C; Klaenhammer, T R



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


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

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



An approach to an objective background subtraction for elemental mapping with core-edges down to 50 eV: description, evaluation and application.  


To image the distribution of a specific element in a specimen with an energy filtering TEM, the element-unspecific background under the core-edge has to be subtracted. The most commonly used procedure is the three-window power-law method leading to considerable systematic errors for low-energy core-edges. Here a new method is described which can be considered as a generalized difference method. Characteristic examples for element detection in biological specimens using this method are shown. The background under the core-edge can be described by one or two pre-edge windows as a polynome of third order. This function can be deduced from specimen areas that are not known to contain the element or from a second specimen used as a standard. Control experiments showed that background subtraction for on-overlapping core-edges in the low-loss region (50-200 eV) needs two pre-edge images, whereas at higher-energy losses (> 300 eV) only one pre-edge image is necessary. With the method described, objective elemental mapping becomes possible even for edges at 50-100 eV. This was proven for the M2,3-edge of iron at 60 eV. The detection of phosphorous was possible with a signal-to-noise ratio five times higher than when using the three-window method. Preliminary data showed that it should be possible to detect calcium with only one image before the edge. PMID:10573828

Haking, A; Troester, H; Richter, K; Crucifix, C; Spring, H; Trendelenburg, M F



Porous Silica Sol-Gel Glasses Containing Reactive V2O5 Groups  

NASA Technical Reports Server (NTRS)

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

Stiegman, Albert E.



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

SciTech Connect

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

Despotopulos, J D; Sudowe, R



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

NASA Astrophysics Data System (ADS)

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

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



Detection vs. grouping thresholds for elements differing in spacing, size and luminance. An alternative approach towards the psychophysics of Gestalten.  


Three experiments were performed to compare thresholds for the detection of non-uniformity in spacing, size and luminance with thresholds for grouping. In the first experiment a row of 12 black equi-spaced dots was used and the spacing after the 3rd, 6th, and 9th dot increased in random steps to determine the threshold at which the observer detected an irregularity in the size of the gaps. Thereafter, spacing in the same locations was increased further to find the threshold at which the observer perceived four groups of three dots each (triplets). In the second experiment, empty circles were used instead of dots and the diameter of the circles in the first and second triplet increased until the difference in size gave rise either to a detection or grouping response. In the third experiment, the dots in the second and fourth triplet were increased in luminance. The aim again was to compare the difference in brightness required for detection or grouping, respectively. Results demonstrate that the threshold for perceiving stimuli as irregularly spaced or dissimilar in size or brightness is much smaller than the threshold for grouping. In order to perceive stimuli as grouped, stimulus differences had to be 5.2 times (for dot spacing), 7.4 times (for size) and 6.6 times (for luminance) larger than for detection. Two control experiments demonstrated that the difference between the two kinds of thresholds persisted even when only two gaps were used instead of three and when gap position was randomized. PMID:20363241

Gori, Simone; Spillmann, Lothar



L-subshell ionization of heavy elements by carbon and nitrogen ions of energy 0.4-1.8 MeV\\/amu  

Microsoft Academic Search

L-shell x-ray production and subshell ionization cross sections have been measured for 0.4-1.8-MeV\\/amu carbon and nitrogen ions for selected heavy elements with 72<=Z2<=90. The results are compared with the predictions of the ECPSSR theory [perturbed-stationary-state (PSS) theory with energy-loss (E), Coulomb deflection (C), and relativistic (R) corrections] describing both direct ionization and electron-capture processes and the semiclassical approximation (SCA) calculations

J. Semaniak; J. Braziewicz; M. Pajek; T. Czyzewski; L. Glowacka; M. Jaskóla; M. Haller; R. Karschnick; W. Kretschmer; Z. Halabuka; D. Trautmann



Measurement of L X-ray production cross sections by 400-700 keV proton impact on rare earth elements  

Microsoft Academic Search

The L-shell X-ray production cross sections of rare earth elements Dy, Ho, Er, Tm, Yb, and Lu by the impact of protons with energies between 400 and 700 keV have been measured. Thin films of the rare earth fluorides have been employed as targets. A comparison with the predictions given by the ECPSSR theory of Brandt and Lapicki, following the

L. Rodríguez-Fernández; J. Miranda; A. Oliver; F. Cruz; J. R. Pegueros



L-subshell ionization cross sections of some rare-earth elements by impact of 2 MeV ? ions: dependence on atomic number  

Microsoft Academic Search

Measurements of L-shell x-rays and Rutherford backscattering in some rare-earth elements produced by 2 MeV 0953-4075\\/31\\/20\\/015\\/img2 ions were used to study the dependence of individual L-subshell ionization cross sections on atomic number. The results were compared with the theoretical predictions of the ECPSSR theory. The discrepancies observed were reduced but not completely overcome by the inclusion of modifications to the

A. B. Hallak



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. PMID:22137173

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.



Barclays Bank PLC v. Franchise Tax Board of California: Does the Application of Worldwide Unitary Taxation to Non-U.S. Parent Corporate Groups Violate the Commerce Clause?  

Microsoft Academic Search

This Comment examines whether the Supreme Court in Barclays v. Franchise Tax Board, correctly decided that the application of worldwide unitary taxation to non-U.S. parent groups does not violate the Commerce Clause.

Zain E. Husain



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



An accuracy assessment of photo-ionization cross-section datasets for 1-2 keV x-rays in light elements using PIXE  

NASA Astrophysics Data System (ADS)

Proton-induced x-ray emission (PIXE) was used to assess the accuracy of the National Institute of Standards and Technology XCOM and FFAST photo-ionization cross-section databases in the low energy region (1-2 keV) for light elements. Characteristic x-ray yields generated in thick samples of Mg, Al and Si in elemental and oxide form, were compared to fundamental parameters computations of the expected x-ray yields; the database for this computation included XCOM attenuation coefficients. The resultant PIXE instrumental efficiency constant was found to differ by 4-6% between each element and its oxide. This discrepancy was traced to use of the XCOM Hartree-Slater photo-electric cross-sections. Substitution of the FFAST Hartree-Slater cross-sections reduced the effect. This suggests that for 1-2 keV x-rays in light element absorbers, the FFAST predictions of the photo-electric cross-sections are more accurate than the XCOM values.

Heirwegh, C. M.; Pradler, I.; Campbell, J. L.



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



Comparison of the group V and VI transition metal carbides for methane dry reforming and thermodynamic prediction of their relative stabilities  

Microsoft Academic Search

The group V and VI transition metal carbides have been prepared by CH4 TPR, and tested for the dry reforming of methane with carbon dioxide, at elevated pressure. Mo2C and WC were the most stable catalysts, while the group V metal carbides showed the stability order: vanadium \\u000a $${\\\\text{ >}}$$\\u000a niobium \\u000a $${\\\\text{ >}}$$\\u000a tantalum. Catalyst deactivation was due to carbide oxidation

Attila J. Brungs; Andrew P. E. York; Malcolm L. H. Green



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

Microsoft Academic Search

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

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



A. Borel, Linear Algebraic Groups [Russian translation], Mir, Moscow (1972). V. E. Voskresenskii, Algebraic Tori [in Russian], Nauka, Moscow (1966)o  

E-print Network

3. 4. 5. 6 7 8 9 i0 ii 12 13. A. Borel, Linear Algebraic Groups [Russian translation], Mir, Moscow of the Classical Groups [Russian translation], Mir, Moscow (1974). V. P. Platonov, "The Tannaka--Artin problem translation], Mir, Moscow (1969). P. Draxl, "SKI von Algebren uber vollstandig diskret bewerteten Korpern und

Grigoriev, Dima


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



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

USGS Publications Warehouse

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

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



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


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

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



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

NASA Astrophysics Data System (ADS)

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

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



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

USGS Publications Warehouse

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

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



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

PubMed Central

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



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

Microsoft Academic Search

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

Zaida Hall; Elizabeth King



M I N I R E V I E W Patchydistribution of exible genetic elements in bacterial  

E-print Network

agalactiae, or seven strains of Escherichia coli, a significant number of new genes were found (Abby & Daubin population heterogeneity; broad host-range plasmids; evolvability; robustness; mobile genetic elements between individuals within bacterial populations. Broad host-range plasmids foster this heterogeneity

Abdo, Zaid


Wafer temperature and stress profiles in an MeV ion implanter using the finite-element method  

Microsoft Academic Search

Temperature profiles produced by an ion beam striking a silicon wafer in a batch process are determined using finite-element analysis (FEA). The fast scan is analyzed for temperature depth profile and transient characteristics. Effects of beam diameter and fast-scan speed are obtained. Uniform thermalization and nonuniform thermalization in the implant layer are examined. Transient thermal stresses resulting from temperature differentials

M. LaFontaine; N. Tokoro; J. P. O'Connor



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

USGS Publications Warehouse

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

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



Incompatible Trace Elements in Olivine: Using Sc, Y and V as Temperature and Redox Monitors in Basaltic Magmas  

NASA Astrophysics Data System (ADS)

Olivine is the dominant constituent phase of the Earth's upper mantle and the first silicate mineral to crystallize from primitive basaltic melts on cooling following decompression. The physical and chemical properties of olivine have, therefore, been of great interest to geochemists and geophysicists. Yet, olivine is so poor in incompatible trace elements (phosphorus being the exception) that it features in much geochemical modeling merely as an inert dilutant. Consequently, our understanding of incompatible trace-element partitioning between olivine and silicate melt has lagged behind that of phases such as pyroxenes or garnet, which control bulk crystal/melt partitioning behavior during mantle melting. Advances in trace-element microanalysis, particularly LA-ICP-MS, have now placed the determination of incompatible elements in natural olivines within reach, and recent studies have shown that mantle and magmatic olivines can preserve complex intracrystalline distributions of these elements. The combined major and trace element compositions of phenocrystal olivines could, therefore, provide unique and detailed insights into magmatic evolution. The course of evolution of basaltic magmas depends substantially on their redox state, hence oxygen fugacity, but there is increasing evidence that this intensive thermodynamic variable may be less well understood in basalts than commonly supposed. The redox state of terrestrial basalts has to a large extent been inferred from the Fe3+/Fe2+ ratios of their quenched glasses. However, this quantity appears to be significantly affected during late and post-eruptive processes in magmatic systems (e.g. by degassing, charge-transfer reactions of redox-variable species, and alteration), so that the degree to which the Fe3+/Fe2+ ratios preserved in basaltic glasses reflect the oxidation state of the magma at high temperature is unclear. The equilibrium partitioning relations preserved in olivine phenocrysts in basalts are, in principle, less disturbed by these late and post-eruptive processes and, therefore, may better represent the high-temperature (pre-eruptive) conditions of the magma. We will present a calibration of an empirical oxybarometer (with typical 1? precision of ±0.25 log units) based on the sensitivity of the partition of vanadium between olivine and silicate melt to oxygen fugacity, and a geothermometer (with typical 1? precision of ±15°C) based on the exchange partitioning of Sc and Y between olivine and melt. Application of these methods reveals interesting redox relationships between the different types of terrestrial basalts.

Mallmann, G.; O'Neill, H. S.



L Sub-Shell Cross Sections measured for 75-300 keV protons on Selected Rare-Earth Elements.  

NASA Astrophysics Data System (ADS)

L sub-shell x-ray production cross sections were measured for 75-300 keV proton impact on thick elemental targets ranging from Gd through Yb. X-ray yields were measured using a high-resolution Si(Li) detector with an ultra-thin window. The results were compared with ECPSSR theory with and without the united-atom approximation for the binding-energy effect and the relativistic correction. Multiple ionization effects are also taken into account.

Cipolla, Sam J.



M -shell x-ray production by 0. 6--4. 0MeV protons in ten elements from hafnium to thorium  

Microsoft Academic Search

-shell x-ray production cross sections for selected heavy elements, namely, ââHf, ââTa, ââW, ââRe, ââOs, ââIr, ââPt, ââAu, ââBi, and ââTh, were measured for protons of energy 0.6--4.0 MeV. The experimental results are compared with the predictions of the first Born and semiclassical approximations for {ital M}-shell ionization; these data are also compared with the theory that accounts for the

M. Pajek; A. P. Kobzev; R. Sandrik; A. V. Skrypnik; R. A. Ilkhamov; S. H. Khusmurodov; G. Lapicki



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


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

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



K-shell x-ray production cross sections of selected elements Ti to Sb for 1.0- to 5.0MeV\\/amu ⁷Li ions  

Microsoft Academic Search

K-shell x-ray production cross sections for thin targets of selected ; elements Ti to Sb have been measured for ⁷Li ions in energy steps of 0.2 ; MeV\\/amu in the range from 1.0 to 5.0 MeV\\/amu. Comparisons of the cross-section ; data for the ligher elements (Zâless than or equal to28) to the plane-wave ; Born approximation (PWBA) and the

F. D. McDaniel; Tom J. Gray; R. K. Gardner; G. M. Light; J. L. Duggan; H. A. Van Rinsvelt; R. D. Lear; G. H. Pepper; J. W. Nelson; A. R. Zander



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

PubMed Central

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

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



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



Small carbides of third-row main group elements: structure and bonding in C3X compounds (X = K-Br).  


The molecular structures of third-row main group tricarbides C(3)X (X = K-Br) have been studied by quantum chemical methods. It is found that less electronegative elements (K, Ca, Ga, Ge) favor either fan or rhombic structures (resulting from side interactions with either linear or triangular C(3) units), whereas the more electronegative elements (As, Se, Br) favor linear or three-membered ring structures (resulting from ?-type interactions with either linear or triangular C(3) units). The predicted global minima are of fan type for C(3)K, rhombic for C(3)Ca, C(3)Ga, and C(3)Ge, linear for C(3)As and C(3)Se, and a three-membered ring for C(3)Br. In order to aid in their possible experimental identification the molecular geometries, vibrational frequencies, IR intensities, and dipole moments have been provided. The nature of the interactions has been characterized through an analysis of the electronic charge density. In addition, the relative stability of the different isomers has been also rationalized in terms of an energy decomposition analysis. PMID:23034393

Villanueva, Estefanía F; Redondo, Pilar; Rayón, Víctor M; Barrientos, Carmen; Largo, Antonio



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

NASA Astrophysics Data System (ADS)

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

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



Chalcophile and platinum-group element (PGE) concentrations in the sulfide minerals from the McCreedy East deposit, Sudbury, Canada, and the origin of PGE in pyrite  

NASA Astrophysics Data System (ADS)

Magmatic sulfide deposits consist of pyrrhotite, pentlandite, chalcopyrite (± pyrite), and platinum-group minerals (PGM). Understanding the distribution of the chalcophile and platinum-group element (PGE) concentrations among the base metal sulfide phases and PGM is important both for the petrogenetic models of the ores and for the efficient extraction of the PGE. Typically, pyrrhotite and pentlandite host much of the PGE, except Pt which forms Pt minerals. Chalcopyrite does not host PGE and the role of pyrite has not been closely investigated. The Ni-Cu-PGE ores from the South Range of Sudbury are unusual in that sulfarsenide PGM, rather than pyrrhotite and pentlandite, are the main carrier of PGE, probably as the result of arsenic contribution to the sulfide liquid by the As-bearing metasedimentary footwall rocks. In comparison, the North Range deposits of Sudbury, such as the McCreedy East deposit, have As-poor granites in the footwall, and the ores commonly contain pyrite. Our results show that in the pyrrhotite-rich ores of the McCreedy East deposit Os, Ir, Ru, Rh (IPGE), and Re are concentrated in pyrrhotite, pentlandite, and surprisingly in pyrite. This indicates that sulfarsenides, which are not present in the ores, were not important in concentrating PGE in the North Range of Sudbury. Palladium is present in pentlandite and, together with Pt, form PGM such as (PtPd)(TeBi)2. Platinum is also found in pyrite. Two generations of pyrite are present. One pyrite is primary and locally exsolved from monosulfide solid solution (MSS) in small amounts (<2 wt.%) together with pyrrhotite and pentlandite. This pyrite is unexpectedly enriched in IPGE, As (± Pt) and the concentrations of these elements are oscillatory zoned. The other pyrite is secondary and formed by alteration of the MSS cumulates by late magmatic/hydrothermal fluids. This pyrite is unzoned and has inherited the low concentrations of IPGE and Re from the pyrrhotite and pentlandite that it has replaced.

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



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


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

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



Generation of L sub-shell photo-ionization cross-sections for elements 18? Z?92 at energies .320–115.606 keV (A computer program ‘LSPICS’)  

Microsoft Academic Search

L sub-shell photo-ionization cross-sections, ?Li, for elements 18?Z?92 at energies .320–115.606keV have been generated from an empirical relation fitted to Scofield's L sub-shell photo-ionization cross-section values. The excitation energy E for an element is constrained by the condition that only L and higher shell vacancies are produced in the elements. The closeness of generated and existing values of Scofield's L

Ajay Sharma; Raj Mittal



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

SciTech Connect

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

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



The frequency of factor V Leiden and prothrombin G20210A mutations in Slovak and Roma (Gypsy) ethnic group of Eastern Slovakia.  


Factor V Leiden and prothrombin G20210A are the two most prevalent causes of inherited thrombophilia. The prevalence of these mutations varies widely in healthy Caucasian population. The aim of our study was to determine the frequency of factor V Leiden and prothrombin G20210A mutations in Slovak and Roma ethnic group from Eastern Slovakia. We analyzed 540 asymptomatic individuals (269 individuals of Slovak ethnicity and 271 individuals of Roma ethnicity) by real-time PCR method. The detected allele frequencies were 2.97 versus 6.64 % for factor V Leiden (p = 0.0049), and 0.74 versus 0.92 % for prothrombin mutation (p = 0.7463) in Slovak and Roma population, respectively. The Roma ethnic group had significantly higher prevalence of factor V Leiden mutation when compared to Slovak ethnic group. The allele frequency of factor V Leiden in ethnic Romanies from Eastern Slovakia was one of the highest in Europe. Our results confirm an uneven geographical and ethnic distribution of factor V Leiden. PMID:22562116

Bôžiková, Alexandra; Gabriková, Dana; Sovi?ová, Adriana; Behulová, Regina; Ma?eková, So?a; Boro?ová, Iveta; Petrej?íková, Eva; Soták, Miroslav; Bernasovská, Jarmila; Bernasovský, Ivan



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

SciTech Connect

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

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



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

NASA Technical Reports Server (NTRS)

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

Dwyer, Robert; Meyer, Peter



An empirical formula for L line X-ray production cross-section of elements from Ag to U for protons below 3.5 MeV  

NASA Astrophysics Data System (ADS)

When computing element concentration from proton induced X-ray emission analysis, an important parameter is the X-ray production cross-section. There have been numerous experimental and theoretical works in this field. Nonetheless, although there is a simple analytical formula to compute K X-ray cross-sections, there is no such ones for the L lines. We present here analytical formulas for the cross-section of the three main X-ray lines L?, L? and L? based on experimental data. So far, nearly 3000 values of cross-sections for elements from Ag to U and proton energy ranging from 0.5 to 3.5 MeV have been collected from various references. This experimental data set has been fitted for each X-ray line with an exponential function depending on the proton energy and on the element atomic number. These fitted values have then been compared to the experimental data and with theoretical values obtained by the ECPSSR theory and Coster-Kronig fluorescence yields.

Strivay, D.; Weber, G.



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

PubMed Central

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



Uncertainty Principles for Compact Groups  

E-print Network

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

Gorjan Alagic; Alexander Russell



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

NASA Technical Reports Server (NTRS)

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

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



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

E-print Network

AIMS: The aim of this study is to investigate the origin and evolution of Sc, V, Mn, and Co for a homogeneous and statistically significant sample of stars probing the different populations of the Milky Way, in particular the thin and thick disks. METHODS: Using high-resolution spectra obtained with MIKE, FEROS, SOFIN, FIES, UVES and HARPS spectrographs, we determine Sc, V, Mn, and Co abundances for a large sample of F and G dwarfs in Solar neighbourhood. The method is based on spectral synthesis and using one-dimensional (1-D), plane-parallel, LTE model stellar atmospheres calculated with the MARCS 2012 code. NLTE corrections from literature were applied to Mn and Co. RESULTS: We find that the abundance trends derived for Sc (594 stars), V (466 stars), and Co (567 stars) are very similar to what has been observed for the alpha-elements in the thin and thick disks. On the contrary Mn (569 stars) is generally underabundant relative to the Sun (i.e. [Mn/Fe]<0) for [Fe/H]<0. Also, for Mn, when NLTE correct...

Battistini, Chiara



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

Federal Register 2010, 2011, 2012, 2013, 2014

...No. EL10-79-000] Morris Energy Group, LLC v.PSEG Energy Resources & Trade LLC; PSEG Fossil LLC; and PSEG Power LLC; Notice...filed a complaint against PSEG Energy Resources & Trade, LLC, PSEG Fossil LLC and PSEG Power LLC...




EPA Science Inventory

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


Localization of Group V Phospholipase A2 in Caveolin-enriched Granules in Activated P388D1 Macrophage-like Cells*  

E-print Network

92093-0608 In murine P388D1 macrophages, the generation of prostaglandin E2 in response to long term acid substrate for COX-2-dependent prostaglandin E2 generation. Be- cause Group V PLA2 is a secreted PLA2 and COX-2 for efficient prostaglandin synthesis. The phospholipase A2 (PLA2)1 superfamily

Dennis, Edward A.


Platinum-group element distribution in base-metal sulfides of the Merensky Reef from the eastern and western Bushveld Complex, South Africa  

NASA Astrophysics Data System (ADS)

Base-metal sulfides in magmatic Ni-Cu-PGE deposits are important carriers of platinum-group elements (PGE). The distribution and concentrations of PGE in pentlandite, pyrrhotite, chalcopyrite, and pyrite were determined in samples from the mineralized portion of four Merensky Reef intersections from the eastern and western Bushveld Complex. Electron microprobe analysis was used for major elements, and in situ laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) for trace elements (PGE, Ag, and Au). Whole rock trace element analyses were performed on representative samples to obtain mineralogical balances. In Merensky Reef samples from the western Bushveld, both Pt and Pd are mainly concentrated in the upper chromitite stringer and its immediate vicinity. Samples from the eastern Bushveld reveal more complex distribution patterns. In situ LA-ICP-MS analyses of PGE in sulfides reveal that pentlandite carries distinctly elevated PGE contents, whereas pyrrhotite and chalcopyrite only contain very low PGE concentrations. Pentlandite is the principal host of Pd and Rh in the ores. Palladium and Rh concentrations in pentlandite reach up to 700 and 130 ppm, respectively, in the samples from the eastern Bushveld, and up to 1,750 ppm Pd and up to 1,000 ppm Rh in samples from the western Bushveld. Only traces of Pt are present in the base-metal sulfides (BMS). Pyrrhotite contains significant though generally low amounts of Ru, Os, and Ir, but hardly any Pd or Rh. Chalcopyrite contains most of the Ag but carries only extremely low PGE concentrations. Mass balance calculations performed on the Merensky Reef samples reveal that in general, pentlandite in the feldspathic pyroxenite and the pegmatoidal feldspathic pyroxenite hosts up to 100 % of the Pd and Rh and smaller amounts (10-40 %) of the Os, Ir, and Ru. Chalcopyrite and pyrrhotite usually contain less than 10 % of the whole rock PGE. The remaining PGE concentrations, and especially most of the Pt (up to 100 %), are present in the form of discrete platinum-group minerals such as cooperite/braggite, sperrylite, moncheite, and isoferroplatinum. Distribution patterns of whole rock Cu, Ni, and S versus whole rock Pd and Pt show commonly distinct offsets. The general sequence of "offset patterns" of PGE and BMS maxima, in the order from bottom to top, is Pd in pentlandite ? Pd in whole rock ? (Cu, Ni, and S). The relationship is not that straightforward in general; some of the reef sequences studied only partially show similar trends or are more complex. In general, however, the highest Pd concentrations in pentlandite appear to be related to the earliest, volumetrically rather small sulfide liquids at the base of the Merensky Reef sequence. A possible explanation for the offset patterns may be Rayleigh fractionation.

Osbahr, Inga; Klemd, Reiner; Oberthür, Thomas; Brätz, Helene; Schouwstra, Robert



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

USGS Publications Warehouse

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

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



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

NASA Astrophysics Data System (ADS)

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

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



Synthesis, surface group modification of 3D MnV{sub 2}O{sub 6} nanostructures and adsorption effect on Rhodamine B  

SciTech Connect

Highlights: ? Fabrication of urchin-like MnV{sub 2}O{sub 6} with oxygen-containing surface groups. ? Mn{sub 0.5}V{sub 2}O{sub 5}·nH{sub 2}O as an intermediate product holds the key to the final products. ? 3D architectures of MnV{sub 2}O{sub 6} with oxygen-containing surface groups as sorbent. ? The sorbent shows a good adsorption ability. -- Abstract: Highly uniform 3D MnV{sub 2}O{sub 6} nanostructures modified by oxygen functional groups (-COO-) were successfully prepared in large quantities by an approach involving preparation of vanadyl ethylene glycolate as the precursor. The growth and self-assembly of MnV{sub 2}O{sub 6} nanobelts and nanorods could be readily tuned by additive species and quantities, which brought different morphologies and sizes to the final products. With a focus on the regulation of structure, the formation process of 3D architectures of MnV{sub 2}O{sub 6} by self-assembly of nanobelts was followed by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The consecutive processes of vanadyl ethylene glycolate and benzoyl peroxide assisted formation of layered structure Mn{sub 0.5}V{sub 2}O{sub 5}·nH{sub 2}O, growth of aligned MnV{sub 2}O{sub 6} nanobelts, and oriented assembly were proposed for the growth mechanism. The band gap vs. different morphology was also studied. Optical characterization of these MnV{sub 2}O{sub 6} with different morphologies showed direct bandgap energies at 1.8–1.95 eV. The adsorption properties of 3D MnV{sub 2}O{sub 6} nanostructures synthesized under different conditions were investigated through the removal test of Rhodamine B in aqueous water, and the 3D nanostructures synthesized with 30 g L{sup ?1} benzoyl peroxide showed good adsorption capability of Rhodamine B.

Zhang, Wanqun, E-mail: [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China) [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Chemical Experimental Teaching Center, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, Lei, E-mail: [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tang, Kaibin; Liu, Zhongping [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Hefei National Laboratory for Physical Sciences at Micro-scale, University of Science and Technology of China, Hefei, Anhui 230026 (China)



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

NASA Astrophysics Data System (ADS)

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

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



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

NASA Astrophysics Data System (ADS)

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

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



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



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.



Pt-Pd reefs in magnetitites of the Stella layered intrusion, South Africa: A world of new exploration opportunities for platinum group elements  

NASA Astrophysics Data System (ADS)

The 3033 Ma Stella layered intrusion of South Africa consists largely of magnetite gabbros and gabbros that are hosted by greenstones of the Kraaipan belt. The intrusion contains a 100-m-thick, platinum group element (PGE) enriched interval that includes a number of laterally continuous PGE reefs constituting the oldest mineralization of this type known on Earth. The richest of the reefs is hosted by magnetitite and contains 10 15 ppm Pt + Pd over 1 m, representing by far the highest PGE grades known up to this time in magnetitite-hosted Pt-Pd reefs. The PGEs are interpreted to have been concentrated by sulfide melt, after S saturation had been reached in the advanced stages of magmatic differentiation, in response to magnetite crystallization. Reaction between sulfide melt and oxides led to late magmatic S loss, causing a paucity of sulfides in most of the PGE mineralized interval. As a result, the reefs cannot be distinguished macroscopically from their unmineralized host rocks, and we suggest that similar mineralization may have been overlooked in the upper parts of other tholeiitic intrusions elsewhere.

Maier, W. D.; Barnes, S.-J.; Gartz, V.; Andrews, G.



The eccentric massive binary V380 Cyg: revised orbital elements and interpretation of the intrinsic variability of the primary component*  

NASA Astrophysics Data System (ADS)

We present a detailed analysis and interpretation of the high-mass binary V380 Cyg, based on high-precision space photometry gathered with the Kepler space mission as well as high-resolution ground-based spectroscopy obtained with the HERMES spectrograph attached to the 1.2 m Mercator telescope. We derive a precise orbital solution and the full physical properties of the system, including dynamical component mass estimates of 11.43 ± 0.19 and 7.00 ± 0.14 M? for the primary and secondary, respectively. Our frequency analysis reveals the rotation frequency of the primary in both the photometric and spectroscopic data and additional low-amplitude stochastic variability at low frequency in the space photometry with characteristics that are compatible with recent theoretical predictions for gravity-mode oscillations excited either by the convective core or by sub-surface convective layers. Doppler imaging analysis of the silicon lines of the primary suggests the presence of two high-contrast stellar surface abundance spots which are located either at the same latitude or longitude. Comparison of the observed properties of the binary with present-day single-star evolutionary models shows that the latter are inadequate and lack a serious amount of near-core mixing.

Tkachenko, A.; Degroote, P.; Aerts, C.; Pavlovski, K.; Southworth, J.; Pápics, P. I.; Moravveji, E.; Kolbas, V.; Tsymbal, V.; Debosscher, J.; Clémer, K.



Evaluation of cross sections for L? x-ray production by up to 4 MeV protons in representative elements from silver to uranium  

NASA Astrophysics Data System (ADS)

Over the last two decades, L? x-ray production cross sections have been fitted with a number of empirical formulae. Cross sections obtained from these formulae are averaged and fitted to a new empirical formula. These new empirical cross sections are compared with the results of the plane-wave Born approximation and the ECPSSR theory of Brandt and Lapicki (1981 Phys. Rev. A 23 1717). They are also gauged by the ECPSSR theory that has been corrected with a united atom approach in slow collisions, evaluated with Dirac-Hartree-Slater instead of screened hydrogenic wavefunctions, modified for intra-shell couplings as well as the change of the atomic parameters due to multiple ionizations. The effects of appropriately normalized intra-shell coupling factors and of multiple ionization were found to be small and essentially offset each other. The role of different sets of atomic parameters in conversion of the predictions of these ionization theories for L? x-ray production in elements from the 47 <= Z2 <= 92 range of target atoms bombarded by up to 4 MeV protons is examined, and the selection of the optimal combination of ionization theory and atomic parameters for a reliable data base for PIXE analysis of elements heavier than palladium is discussed.

Lapicki, Gregory



M -shell x-ray production by 0. 6--4. 0-MeV protons in ten elements from hafnium to thorium  

SciTech Connect

{ital M}-shell x-ray production cross sections for selected heavy elements, namely, {sub 72}Hf, {sub 73}Ta, {sub 74}W, {sub 75}Re, {sub 76}Os, {sub 77}Ir, {sub 78}Pt, {sub 79}Au, {sub 83}Bi, and {sub 90}Th, were measured for protons of energy 0.6--4.0 MeV. The experimental results are compared with the predictions of the first Born and semiclassical approximations for {ital M}-shell ionization; these data are also compared with the theory that accounts for the projectile's energy loss and Coulomb deflection as well as for the target's {ital M}-shell electron perturbed stationary state and relativistic nature (ECPSSR). Generally, fair agreement between the data and the ECPSSR theory is found. Some systematical discrepancies observed for the lightest elements (Hf, Ta, and W) are explained as possible ambiguities in the {ital M}-shell Coster-Kronig factors and fluorescence yields, which were used to convert theoretical {ital M}-subshell ionization cross sections to the total {ital M}-x-ray production cross sections. The experimental total {ital M}-shell ionization cross sections were obtained from measured {ital M}-x-ray cross sections using the proposed approximate average fluorescence yield {bar {omega}}{sub {ital M}} that relies on two fluorescence yields and the Coster-Kronig factor for {ital only} {ital M}{sub 4} and {ital M}{sub 5} subshells.

Pajek, M. (Institute of Physics, Pedagogical University, 25-509 Kielce, Poland (PL)); Kobzev, A.P.; Sandrik, R.; Skrypnik, A.V. (Joint Institute for Nuclear Research, Dubna (U.S.S.R.)); Ilkhamov, R.A.; Khusmurodov, S.H. (Institute of Applied Physics, Tashkent State University, Tashkent (U.S.S.R.)); Lapicki, G. (Department of Physics, East Carolina University, Greenville, NC (USA))



Systematic investigation of the metal-structure-photophysics relationship of emissive d10-complexes of group 11 elements: the prospect of application in organic light emitting devices.  


A series of new emissive group 11 transition metal d(10)-complexes 1-8 bearing functionalized 2-pyridyl pyrrolide together with phosphine ancillary such as bis[2-(diphenylphosphino)phenyl] ether (POP) or PPh(3) are reported. The titled complexes are categorized into three classes, i.e. Cu(I) complexes (1-3), Ag(I) complexes (4 and 5), and Au(I) metal complexes (6-8). Via combination of experimental and theoretical approaches, the group 11 d(10)-metal ions versus their structural variation, stability, and corresponding photophysical properties have been investigated in a systematic and comprehensive manner. The results conclude that, along the same family, how much a metal d-orbital is involved in the electronic transition plays a more important role than how heavy the metal atom is, i.e. the atomic number, in enhancing the spin-orbit coupling. The metal ions with and without involvement of a d orbital in the lowest lying electronic transition are thus classified into internal and external heavy atoms, respectively. Cu(I) complexes 1-3 show an appreciable metal d contribution (i.e., MLCT) in the lowest lying transition, so that Cu(I) acts as an internal heavy atom. Despite its smallest atomic number among group 11 elements, Cu(I) complexes 1-3 exhibit a substantially larger rate of intersystem crossing (ISC) and phosphorescence radiative decay rate constant (k(r)(p)) than those of Ag(I) (4 and 5) and Au(I) (6-8) complexes possessing pure ? ? ?* character in the lowest transition. Since Ag(I) and Au(I) act only as external heavy atoms in the titled complexes, the spin-orbit coupling is mainly governed by the atomic number, such that complexes associated with the heavier Au(I) (6-8) show faster ISC and larger k(r)(p) than the Ag(I) complexes (4 and 5). This trend of correlation should be universal and has been firmly supported by experimental data in combination with empirical derivation. Along this line, Cu(I) complex 1 exhibits intensive phosphorescence (?(p) = 0.35 in solid state) and has been successfully utilized for fabrication of OLEDs, attaining peak EL efficiencies of 6.6%, 20.0 cd/A, and 14.9 lm/W for the forward directions. PMID:21711042

Hsu, Chien-Wei; Lin, Chao-Chen; Chung, Min-Wen; Chi, Yun; Lee, Gene-Hsiang; Chou, Pi-Tai; Chang, Chih-Hao; Chen, Pin-Yang



Elements & Compounds Atoms (Elements)  

E-print Network

#12;Elements & Compounds #12;Atoms (Elements) Molecules (Compounds) Cells Elements & Compounds #12;Nucleus Electrons Cloud of negative charge (2 electrons) Fig. 2.5: Simplified model of a Helium (He) Atom He 4.002602 2 Helium Mass Number (~atomic mass) = number of Neutrons + Protons = 4 for Helium Atomic

Frey, Terry


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



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

NASA Technical Reports Server (NTRS)

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

Thompson David S.; Soni, Bharat K.



Group V Secreted Phospholipase A2 Is Upregulated by IL-4 in Human Macrophages and Mediates Phagocytosis via Hydrolysis of Ethanolamine Phospholipids.  


Studies on the heterogeneity and plasticity of macrophage populations led to the identification of two major polarization states: classically activated macrophages or M1, induced by IFN-? plus LPS, and alternatively activated macrophages, induced by IL-4. We studied the expression of multiple phospholipase A2 enzymes in human macrophages and the effect that polarization of the cells has on their levels. At least 11 phospholipase A2 genes were found at significant levels in human macrophages, as detected by quantitative PCR. None of these exhibited marked changes after treating the cells with IFN-? plus LPS. However, macrophage treatment with IL-4 led to strong upregulation of the secreted group V phospholipase A2 (sPLA2-V), both at the mRNA and protein levels. In parallel with increasing sPLA2-V expression levels, IL-4-treated macrophages exhibited increased phagocytosis of yeast-derived zymosan and bacteria, and we show that both events are causally related, because cells deficient in sPLA2-V exhibited decreased phagocytosis, and cells overexpressing the enzyme manifested higher rates of phagocytosis. Mass spectrometry analyses of lipid changes in the IL-4-treated macrophages suggest that ethanolamine lysophospholipid (LPE) is an sPLA2-V-derived product that may be involved in regulating phagocytosis. Cellular levels of LPE are selectively maintained by sPLA2-V. By supplementing sPLA2-V-deficient cells with LPE, phagocytosis of zymosan or bacteria was fully restored in IL-4-treated cells. Collectively, our results show that sPLA2-V is required for efficient phagocytosis by IL-4-treated human macrophages and provide evidence that sPLA2-V-derived LPE is involved in the process. PMID:25725101

Rubio, Julio M; Rodríguez, Juan P; Gil-de-Gómez, Luis; Guijas, Carlos; Balboa, María A; Balsinde, Jesús



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.

Dexter Perkins


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

PubMed Central

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

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



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

NASA Astrophysics Data System (ADS)

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

Barnes, Stephen J.



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


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

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



K-shell x-ray production cross sections of selected elements Ti to Sb for 1.0- to 5.0MeV\\/amu 7Li ions  

Microsoft Academic Search

K-shell x-ray production cross sections for thin targets of selected elements Ti to Sb have been measured for 7Li ions in energy steps of 0.2 MeV\\/amu in the range from 1.0 to 5.0 MeV\\/amu. Comparisons of the cross-section data for the lighter elements (Z2<=28) to the plane-wave Born approximation (PWBA) and the PWBA corrected for binding energy and Coulomb deflection

F. D. McDaniel; Tom J. Gray; R. K. Gardner; G. M. Light; J. L. Duggan; H. A. van Rinsvelt; R. D. Lear; G. H. Pepper; J. William Nelson; Arlen R. Zander



Selenium and sulfur concentrations in the Bushveld Complex of South Africa and implications for formation of the platinum-group element deposits  

Microsoft Academic Search

We have determined the S, Se, Cu and La contents through a complete stratigraphic section of the Bushveld Complex. The principle aim was to determine which phases controlled these elements. S, Se and Cu show positive correlations, but these elements do not correlate with La. In most cases, the concentration of S, Se and Cu in rocks containing greater than

Sarah-Jane Barnes; Dany Savard; L. Paul Bédard; Wolfgang D. Maier



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

NASA Astrophysics Data System (ADS)

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

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



On Some Algebraic and Combinatorial Properties of Dunkl Elements  

NASA Astrophysics Data System (ADS)

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

Kirillov, Anatol N.



On Some Algebraic and Combinatorial Properties of Dunkl Elements  

NASA Astrophysics Data System (ADS)

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

Kirillov, Anatol N.



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

PubMed Central

GBS serotypes III and V were the most prevalent in pregnant women and exhibited resistance to tetracycline, clindamycin and sulfamethoxazole/trimethoprim. Serotype III showed high sialic acid content and PFGE analysis discerned 33 heterogeneous profiles. Phenotypic and genotypic characterization could be relevant to control GBS infections unaffected by intra-partum chemoprophylaxis. PMID:24516454

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



Automata groups  

E-print Network

of Mihailova normal form concerns only free groups, it can be useful for any group G, and we will use the following natural 11 definition: Definition II.12. Let G be a group with non-trivial generators{a1,...,an}, and H be a subgroup of the direct product G... to show that the defining relators in the group ?? are mapped to the trivial element of the group ???. In all three cases we have ??(a)2 = ((1,1)?)2 = (1,1), ??(x)2 = (1,?x2) = (1,1), ??(y)2 = (?a2,?y2) = (1,1), ??(z)2 = (?a2,?z2) = (1,1), ??(x...

Muntyan, Yevgen



[Memorandum 'Development of Health Services Research in Bavaria from the Perspective of the Bavarian State Working Group 'Health Services Research (LAGeV)': Status quo - Potential - Strategies'].  


The aim of the memorandum on the development of health services research (HSR) in Bavaria is to operationalise the global objectives of the State Working Group "Health Services Research" (LAGeV) and to collectively define future topics, specific implementation steps, methods as well as ways of working for the future course of the LAGeV. The LAGeV is an expert committee that integrates and links the competencies of different actors from science, politics and health care regarding HSR and facilitates their cooperation. The memorandum is based on an explorative survey among the LAGeV members, which identified the status quo of health services research in Bavaria, potential for development, important constraints, promoting factors, specific recommendations as well as future topics for the further development of HSR in Bavaria. From the perspective of the LAGeV members, the 12 most important future topics are: 1) Interface and networking research, 2) Innovative health care concepts, 3) Health care for multimorbid patients, 4)Health care for chronically ill patients, 5) Evaluation of innovations, processes and technologies, 6) Patient orientation and user focus, 7) Social and regional inequalities in health care, 8) Health care for mentally ill patients, 9) Indicators of health care quality, 10) Regional needs planning, 11) Practical effectiveness of HSR and 12) Scientific use of routine data. Potential for development of HSR in Bavaria lies a) in the promotion of networking and sustainable structures, b) the establishment of an HSR information platform that bundles information and results in regard to current topics and aims to facilitate cooperation as well as c) in the initiation of measures and projects. The latter ought to pinpoint health care challenges and make recommendations regarding the improvement of health care and its quality. The cooperation and networking structures that were established with the LAGeV should be continuously expanded and be used to work on priority topics in order to achieve the global objectives of the LAGeV. PMID:25422951

Hollederer, A; Braun, G E; Dahlhoff, G; Drexler, H; Engel, J; Gräßel, E; Häusler, E; Heide, H; Heuschmann, P U; Hörl, G; Imhof, H; Kaplan, M; Kasperbauer, R; Klemperer, D; Kolominsky-Rabas, P; Kuhn, J; Lang, M; Langejürgen, R; Lankes, A; Leidl, R; Liebl, B; Loss, J; Ludewig, K; Mansmann, U; Melcop, N; Nagels, K; Nowak, D; Pfundner, H; Reuschenbach, B; Schneider, A; Schneider, W; Schöffski, O; Schreiber, W; Voigtländer, S; Wildner, M; Zapf, A; Zellner, A



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

NASA Technical Reports Server (NTRS)

The nature of Re-platinum-group element (PGE; Pt, Pd, Ir, Os, Ru) transport in the marine environment was investigated by means of marine sediments at and across the Cretaceous-Tertiary boundary (KTB) at two hemipelagic sites in Europe and two pelagic sites in the North and South Pacific. A traverse across the KTB in the South Pacific pelagic clay core found elevated levels of Re, Pt, Ir, Os, and Ru, each of which is approximately symmetrically distributed over a distance of approx. 1.8 m across the KTB. The Re-PGE abundance patterns are fractionated from chondritic relative abundances: Ru, Pt, Pd, and Re contents are slightly subchondritic relative to Ir, and Os is depleted by approx. 95% relative to chondritic Ir proportions. A similar depletion in Os (approx. 90%) was found in a sample of the pelagic KTB in the North Pacific, but it is enriched in Ru, Pt, Pd, and Re relative to Ir. The two hemipelagic KTB clays have near-chondritic abundance patterns. The approx. 1.8-m-wide Re-PGE peak in the pelagic South Pacific section cannot be reconciled with the fallout of a single impactor, indicating that postdepositional redistribution has occurred. The elemental profiles appear to fit diffusion profiles, although bioturbation could have also played a role. If diffusion had occurred over approx. 65 Ma, the effective diffusivities are approx. 10(exp -13)sq cm/s, much smaller than that of soluble cations in pore waters (approx. 10(exp -5) sq cm/s). The coupling of Re and the PGEs during redistribution indicates that postdepositional processes did not significantly fractionate their relative abundances. If redistribution was caused by diffusion, then the effective diffusivities are the same. Fractionation of Os from Ir during the KTB interval must therefore have occurred during aqueous transport in the marine environment. Distinctly subchondritic Os/Ir ratios throughout the Cenozoic in the South Pacific core further suggest that fractionation of Os from Ir in the marine environment is a general process throughout geologic time because most of the inputs of Os and Ir into the ocean have OsAr ratios greater than or = 1. Mass balance calculations show that Os and Re burial fluxes in pelagic sediments account for only a small fraction of the riverine Os (less than 10%) and Re (less than 0.1%) inputs into the oceans. In contrast, burial of Ir in pelagic sediments is similar to the riverine Ir input, indicating that pelagic sediments are a much larger repository for Ir than for Os and Re. If all of the missing Os and Re is assumed to reside in anoxic sediments in oceanic margins, the calculated burial fluxes in anoxic sediments are similar to observed burial fluxes. However, putting all of the missing Os and Re into estuarine sediments would require high concentrations to balance the riverine input and would also fail to explain the depletion of Os at pelagic KTB sites, where at most approx. 25% of the K-T impactor's Os could have passed through estuaries. If Os is preferentially sequestered in anoxic marine environments, it follows that the OsAr ratio of pelagic sediments should be sensitive to changes in the rates of anoxic sediment deposition. There is thus a clear fractionation of Os and Re from Ir in precipitation out of sea water in pelagic sections. Accordingly, it is inferred here that Re and Os are removed from sea water in anoxic marine depositional regimes.

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



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

NASA Astrophysics Data System (ADS)

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

Tarasov, V. F.


M-shell x-ray production by 0.8-4.0-MeV 4He+ ions in ten elements from hafnium to thorium  

NASA Astrophysics Data System (ADS)

M-shell x-ray production cross sections are reported for 72Hf, 73Ta, 74W, 75Re, 76Os, 77Ir, 78Pt, 79Au, 83Bi, and 90Th bombarded by 4He ions of energy 0.8-4.0 MeV. The measured cross sections are compared with the predictions of the semiclassical and first-order Born approximations and the calculations of the perturbed-stationary-state (PSS) theory that accounts for energy-loss (E), Coulomb deflection (C), and relativistic (R) effects (ECPSSR). The ECPSSR theory gives the best overall description of the measured data, although systematical discrepancies are found in the low-velocity region. Apart from deficiency of the available M-shell Coster-Kronig factors and fluorescence yields near or above Z2=74, where strong M4-M5N6,7 Coster-Kronig transitions become energetically forbidden, the increasing underestimation of the data by the ECPSSR theory with decreasing projectile velocities is genuine. In fact, we have found previously [Pajek et al., Phys. Rev. A 42, 261 (1990)] the same discrepancy for identical target elements bombarded by protons at comparably low velocities.

Pajek, M.; Kobzev, A. P.; Sandrik, R.; Skrypnik, A. V.; Ilkhamov, R. A.; Khusmurodov, S. H.; Lapicki, G.



M -shell x-ray production by 0. 8--4. 0-MeV sup 4 He sup + ions in ten elements from hafnium to thorium  

SciTech Connect

{ital M}-shell x-ray production cross sections are reported for {sub 72}Hf, {sub 73}Ta, {sub 74}W, {sub 75}Re, {sub 76}Os, {sub 77}Ir, {sub 78}Pt, {sub 79}Au, {sub 83}Bi, and {sub 90}Th bombarded by {sup 4}He ions of energy 0.8--4.0 MeV. The measured cross sections are compared with the predictions of the semiclassical and first-order Born approximations and the calculations of the perturbed-stationary-state (PSS) theory that accounts for energy-loss (E), Coulomb deflection (C), and relativistic (R) effects (ECPSSR). The ECPSSR theory gives the best overall description of the measured data, although systematical discrepancies are found in the low-velocity region. Apart from deficiency of the available {ital M}-shell Coster-Kronig factors and fluorescence yields near or above {ital Z}{sub 2}=74, where strong {ital M}{sub 4}-{ital M}{sub 5}{ital N}{sub 6,7} Coster-Kronig transitions become energetically forbidden, the increasing underestimation of the data by the ECPSSR theory with decreasing projectile velocities is genuine. In fact, we have found previously (Pajek {ital et} {ital al}., Phys. Rev. A 42, 261 (1990)) the same discrepancy for identical target elements bombarded by protons at comparably low velocities.

Pajek, M. (Institute of Physics, Pedagogical University, (Poland)); Kobzev, A.P.; Sandrik, R.; Skrypnik, A.V. (Joint Institutefor Nuclear Research, Dubna (USSR)); Ilkhamov, R.A.; Khusmurodov, S.H. (Institute of Applied Physics, Tashkent State University, Tashkent (USSR)); Lapicki, G. (Department of Physics, East Carolina University, Greenville North Carolina (USA))



L-subshell ionization of heavy elements by S ions with energy of 0.4 3.8 MeV/amu  

NASA Astrophysics Data System (ADS)

The L-shell X-ray production cross sections have been measured for sulphur ions in the energy range of 12.8-120 MeV for Au and Bi elements. The experimental L X-ray spectra were analyzed using the method that takes into account the multiple ionization in outer shells. The L-subshell ionization cross sections have been obtained from measured X-ray production cross sections for resolved L? 1,2 L? 1 and L? 2,3 transitions using the L-shell fluorescence and Coster-Kronig yields modified by the multiple ionization effects in the M and N shells. The results are compared with the predictions of ECUSAR theory, which is the modified ECPSSR approach describing both direct ionization and electron-capture processes and the semiclassical approximation (SCA) calculations for direct ionization. These approaches were modified by the L-subshell coupling effects within the "coupled-subshell model" (CSM). Both modified approaches are in good agreement with the data. Remaining discrepancies are discussed in terms of the L-shell decay rates modified for the multiple ionization effects.

Fija?-Kirejczyk, I.; Jaskó?a, M.; Korman, A.; Bana?, D.; Braziewicz, J.; Choi?ski, J.; Majewska, U.; Pajek, M.; Kretchmer, W.; Lapicki, G.; Mukoyama, T.; Trautmann, D.



Are members of low status groups perceived as bad, or badly oV? Egalitarian negative associations and automatic prejudice  

Microsoft Academic Search

Three studies explored the hypothesis that implicit measures of prejudice can tap negative, yet egalitarian associations. In Study 1, automatically associating African Americans with oppression predicted greater automatic prejudice. In Studies 2 and 3, classically condi- tioning associations between the novel group NoYans and words like oppressed, maltreated, and victimized led to greater automatic prej- udice against NoYans. Results suggest

Eric Luis Uhlmann; Victoria L. Brescoll; Elizabeth Levy Paluck



Selenium and sulfur concentrations in the Bushveld Complex of South Africa and implications for formation of the platinum-group element deposits  

Microsoft Academic Search

We have determined the S, Se, Cu and La contents through a complete stratigraphic section of the Bushveld Complex. The principle\\u000a aim was to determine which phases controlled these elements. S, Se and Cu show positive correlations, but these elements do\\u000a not correlate with La. In most cases, the concentration of S, Se and Cu in rocks containing greater than

Sarah-Jane Barnes; Dany Savard; L. Paul Bédard; Wolfgang D. Maier



Cisplatin (P), vinblastine (V) and bleomycin (B) combination chemotherapy in recurrent or advanced granulosa(-theca) cell tumours of the ovary. An EORTC Gynaecological Cancer Cooperative Group study.  


The aim of this study was to investigate the clinical activity and toxicity of a modified PVB regimen (cisplatin, vinblastine and bleomycin) in patients with advanced or recurrent, pure granulosa cell tumours (GCTs) or mixed granulosa-theca cell tumours (GTCTs). The PVB regimen consisted of cisplatin (P) 20 mg/m2 intravenous (i.v.) days 1-5, vinblastine (V) 0.15 mg/kg i.v. days 1-2 and bleomycin (B) 30 mg i.v. on day 2, and 15 mg on day 15, for 28 days. 38 eligible patients were entered in this trial. Prior to PVB all patients underwent surgery and 13 received postoperative radio- or other prior chemotherapy. The median number of PVB cycles was 4 in both groups. In the group of 25 patients who had received prior surgery only, 7 and 6 patients had complete and partial responses, respectively (response rate: 52%, 95% confidence limits: 31.3-72.2%). At a median follow-up of 39 months, 6 patients were alive with no evidence of disease, 6 were alive with disease, 12 died due to malignant disease and 1 died due to intercurrent disease. The median time to progression was 13.9 months. The median survival was 25.4 months. 3-year survival was 49% (95% confidence limits: 29-69%). In the group of 13 patients who had previously received postoperative radio- or chemotherapy, 5 complete and 5 partial responses were observed on PVB (response rate: 77%, 95% confidence limit: 46.2-95.0%). At a median follow-up of 50 months, 6 patients were still alive, only 1 without evidence of disease, 6 died due to malignant disease and 1 died due to intercurrent disease. The median time to progression was 19.3 months. The median duration of survival was 41.1 months. Accompanying toxicity was distributed in a similar pattern for both groups. Severe toxicity was mainly documented as haematological toxicity, nausea/vomiting and alopecia. Furthermore cisplatin-related peripheral neurotoxicity and mild/moderate signs of bleomycin-related pulmonary toxicity were observed. The present data confirm the therapeutic activity of the PVB regimen in advanced/recurrent GCTs. The response rate was moderately high compared with previous studies, with a median duration of response of 20 months for both groups. PMID:10658523

Pecorelli, S; Wagenaar, H C; Vergote, I B; Curran, D; Beex, L V; Wiltshaw, E; Vermorken, J B




EPA Science Inventory

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


Unramified Brauer groups of finite simple groups of Lie type A l  

Microsoft Academic Search

We study the subgroup B_0(G) of H^2(G,Q\\/Z) consisting of all elements which\\u000ahave trivial restrictions to every Abelian subgroup of G. The group B_0(G)\\u000aserves as the simplest nontrivial obstruction to stable rationality of\\u000aalgebraic varieties V\\/G where V is a faithful complex linear representation of\\u000athe group G. We prove that B_0(G) is trivial for finite simple groups of

Fedor Bogomolov; Jorge Maciel; Tihomir Petrov



Single-experiment simultaneous-measurement of elemental mass-attenuation coefficients of hydrogen, carbon and oxygen for 0.123–1.33 MeV gamma rays  

Microsoft Academic Search

As it is inconvenient to use elements like hydrogen, carbon and oxygen in pure forms for measurement of their gamma mass-attenuation coefficients, the measurements are to be done indirectly, by using compounds of the elements or a mixture of them. We give here a simple method of measuring the total mass-attenuation coefficients ?\\/? of the elements in a compound simultaneously

M. T. Teli; R. Nathuram; C. S. Mahajan



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



Proton inelastic mean free path in a group of bioorganic compounds and water in 0.05-10 MeV range - Including higher-order corrections  

NASA Astrophysics Data System (ADS)

The systematic calculations of the inelastic mean free paths (MFP) of 0.05-10 MeV protons in a group of eleven important bioorganic compounds, i.e. DNA, five bases, three fatty acids, cellulose and ?-carotene, have been performed. The expressions for the calculations are derived from the Ashley's optical-data model and from the higher-order correction terms in stopping power calculations. Especially, the Bloch correction for the inelastic MFP is proposed empirically in this work. The inelastic MFPs for energetic protons in water are also evaluated and compared with other theoretical calculations. The proton inelastic MFPs for these 11 bioorganic compounds in the energy range from 0.05 to 10 MeV are presented here for the first time, and might be useful for studies of various radiation effects in these materials.

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



Batisivite, V8Ti6[Ba(Si2O)]O28, a new mineral species from the derbylite group  

NASA Astrophysics Data System (ADS)

Batisivite has been found as an accessory mineral in the Cr-V-bearing quartz-diopside metamorphic rocks of the Slyudyanka Complex in the southern Baikal region, Russia. A new mineral was named after the major cations in its ideal formula (Ba, Ti, Si, V). Associated minerals are quartz, Cr-V-bearing diopside and tremolite; calcite; schreyerite; berdesinskiite; ankangite; V-bearing titanite; minerals of the chromite-coulsonite, eskolaite-karelianite, dravite-vanadiumdravite, and chernykhite-roscoelite series; uraninite; Cr-bearing goldmanite; albite; barite; zircon; and unnamed U-Ti-V-Cr phases. Batisivite occurs as anhedral grains up to 0.15-0.20 mm in size, without visible cleavage and parting. The new mineral is brittle, with conchoidal fracture. Observed by the naked eye, the mineral is black and opaque, with a black streak and resinous luster. Batisivite is white in reflected light. The microhardness (VHN) is 1220-1470 kg/mm2 (load is 30 g), the mean value is 1330 kg/mm2. The Mohs hardness is near 7. The calculated density is 4.62 g/cm3. The new mineral is weakly anisotropic and bireflected. The measured values of reflectance are as follows (?, nm— R {max/'}/ R {min/'}): 440—17.5/17.0; 460—17.3/16.7; 480—17.1/16.5; 500—17.2/16.6; 520—17.3/16.7; 540—17.4/16.8; 560—17.5/16.8; 580—17.6/16.9; 600—17.7/17.1; 620—17.7/17.1; 640—17.8/17.1; 660—17.9/17.2; 680—18.0/17.3; 700—18.1/17.4. Batisivite is triclinic, space group P overline 1 ; the unit-cell dimensions are: a = 7.521(1) Å, b = 7.643(1) Å, c = 9.572(1) Å, ? = 110.20°(1), ? = 103.34°(1), ? = 98.28°(1), V = 487.14(7) Å3, Z = 1. The strongest reflections in the X-ray powder diffraction pattern [ d, Å ( I, %)( hkl)] are: 3.09(8)(12 overline 2 ); 2.84, 2.85(10)(021, 120); 2.64(8)(21 overline 3 ); 2.12(8)(31 overline 3 ); 1.785(8)(32 overline 4 ), 1.581(10)(24 overline 2 ); 1.432, 1.433(10)(322, 124). The chemical composition (electron microprobe, average of 237 point analyses, wt %) is: 0.26 Nb2O5, 6.16 SiO2, 31.76 TiO2, 1.81 Al2O3, 8.20 VO2, 26.27 V2O3, 12.29 Cr2O3, 1.48 Fe2O3, 0.08 MgO, 11.42 BaO; the total is 99.73. The VO2/V2O3 ratio has been calculated. The simplified empirical formula is (V{4.8/3+}Cr2.2V{0.7/4+}Fe0.3)8.0(Ti5.4V{0.6/4+})6.0[Ba(Si1.4Al0.5O0.9)]O28. An alternative to the title formula could be a variety (with the diorthogroup Si2O7) V8Ti6[Ba(Si2O7)]O22. Batisivite probably pertains to the V{8/3+}Ti{6/4+}[Ba(Si2O)]O28-Cr{8/3+}Ti{6/4+} [Ba(Si2O)]O28 solid solution series. The type material of batisivite has been deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

Reznitsky, L. Z.; Sklyarov, E. V.; Armbruster, T.; Galuskin, E. V.; Ushchapovskaya, Z. F.; Polekhovsky, Yu. S.; Karmanov, N. S.; Kashaev, A. A.; Barash, I. G.



Charge-injection induced magnetism and half metallicity in single-layer hexagonal group III/V (BN, BP, AlN, AlP) systems  

NASA Astrophysics Data System (ADS)

Based on the first-principles calculations, we predict that strong ferromagnetism and half metallicity can be induced via charge injection in single-layer hexagonal boron nitride (BN) and BN nanoribbons. This phenomenon can be understood based on the Stoner criterion and the relationship between induced magnetic moment and charge density. Other group-III/V two-dimensional honeycomb systems such as boron phosphide (BP), aluminum nitride (AlN), and aluminum phosphide (AIP) exhibit similar ferromagnetic behavior upon charge injection. Like BN, the single-layer hexagonal AlN can be converted to a half metal at certain positive charge states.

Wu, Menghao; Zhang, Zhuhua; Zeng, Xiao Cheng



Lipopolysaccharide-induced release of arachidonic acid and prostaglandins in liver macrophages: Regulation by Group IV cytosolic phospholipase A 2, but not by Group V and Group IIA secretory phospholipase A 2  

Microsoft Academic Search

Lipopolysaccharide (LPS) induces a delayed release (lag phase of 2–4 h) of arachidonic acid (AA) and prostaglandin (PG) D2 in rat liver macrophages. Group IV cytosolic phospholipase A2 (cPLA2) becomes phosphorylated within minutes after the addition of LPS. The phosphorylated form of cPLA2 shows an enhanced in vitro activity. The Ca2+ dependence of cPLA2 activity is not affected by phosphorylation

Peter Dieter; Angelika Kolada; Sabine Kamionka; Alexia Schadow; Marietta Kaszkin



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

NASA Astrophysics Data System (ADS)

We present the orbital and physical parameters of the detached eclipsing binary V1200 Centauri (ASAS J135218-3837.3) from the analysis of spectroscopic observations and light curves from the All-Sky Automated Survey (ASAS) and SuperWASP (Wide Angle Search for Planets) data base. The radial velocities were computed from the high-resolution spectra obtained with the OUC (Observatorio Universidad Católica) 50-cm telescope and PUCHEROS (Pontificia Universidad Católica High Echelle Resolution Optical Spectrograph) spectrograph and with 1.2-m Euler telescope and CORALIE spectrograph using the cross-correlation technique TODCOR. We found that the absolute parameters of the system are M1 = 1.394 ± 0.030 M?, M2 = 0.866 ± 0.015 M?, R1 = 1.39 ± 0.15 R?, R2 = 1.10 ± 0.25 R?. We investigated the evolutionary status and kinematics of the binary and our results indicate that V1200 Centauri is likely a member of the Hyades moving group, but the largely inflated secondary's radius may suggest that the system may be even younger, around 30 Myr. We also found that the eclipsing pair is orbited by another, stellar-mass object on a 351-d orbit, which is unusually short for hierarchical triples. This makes V1200 Cen a potentially interesting target for testing the formation models of multiple stars.

Coronado, J.; He?miniak, K. G.; Vanzi, L.; Espinoza, N.; Brahm, R.; Jordán, A.; Catelan, M.; Ratajczak, M.; Konacki, M.



Implication of TLR- but Not of NOD2-Signaling Pathways in Dendritic Cell Activation by Group B Streptococcus Serotypes III and V  

PubMed Central

Group B Streptococcus (GBS) is an important agent of life-threatening invasive infection. It has been previously shown that encapsulated type III GBS is easily internalized by dendritic cells (DCs), and that this internalization had an impact on cytokine production. The receptors underlying these processes are poorly characterized. Knowledge on the mechanisms used by type V GBS to activate DCs is minimal. In this work, we investigated the role of Toll-like receptor (TLR)/MyD88 signaling pathway, the particular involvement of TLR2, and that of the intracellular sensing receptor NOD2 in the activation of DCs by types III and V GBS. The role of capsular polysaccharide (CPS, one of the most important GBS virulence factors) in bacterial-DC interactions was evaluated using non-encapsulated mutants. Despite differences in the role of CPS between types III and V GBS in bacterial internalization and intracellular survival, no major differences were observed in their capacity to modulate release of cytokines by DC. For both serotypes, CPS had a minor role in this response. Production of cytokines by DCs was shown to strongly rely on MyD88-dependent signaling pathways, suggesting that DCs recognize GBS and become activated mostly through TLR signaling. Yet, GBS-infected TLR2-/- DCs only showed a partial reduction in the production of IL-6 and CXCL1 compared to control DCs. Surprisingly, CXCL10 release by type III or type V GBS-infected DCs was MyD88-independent. No differences in DC activation were observed between NOD2-/- and control DCs. These results demonstrate the involvement of various receptors and the complexity of the cytokine production pathways activated by GBS upon DC infection. PMID:25436906

Lemire, Paul; Roy, David; Fittipaldi, Nahuel; Okura, Masatoshi; Takamatsu, Daisuke; Bergman, Eugenia; Segura, Mariela



Platinum group element geochemistry of komatiites from the Alexo and Pyke Hill areas, Ontario, Canada 1 1 Associate editor: R. J. Walker  

Microsoft Academic Search

Thirty-three whole-rock drill core samples and thirteen olivine, chromite, and sulfide separates from three differentiated komatiite lava flows at Alexo and Pyke Hill, Canada, were analyzed for PGEs using the Carius tube digestion ID-ICP-MS technique. The emplaced lavas are Al-undepleted komatiites with ?27% MgO derived by ?50% partial melting of LILE-depleted Archean mantle. Major and minor element variations during and

Igor S. Puchtel; Munir Humayun; Andrew J. Campbell; Rebecca A. Sproule; C. Michael Lesher



P1 clones from Drosophila melanogaster as markers to study the chromosomal evolution of Muller's A element in two species of the obscura group of Drosophila  

Microsoft Academic Search

Thirty P1 clones from the X chromosome (Muller's A element) of Drosophila melanogaster were cross-hybridized in situ to Drosophila subobscura and Drosophila pseudoobscura polytene chromosomes. An additional recombinant phage ?Dsuby was also used as a marker. Twenty-three (77%) of the P1 clones gave positive hybridization on D. pseudoobscura chromosomes bat only 16 (53%) did so with those of D. subobscura.

Carmen Segarra; Elena R. Lozovskaya; Griselda Ribó; Montserrat Aguadé; Daniel L. Hartl



Baseline Glutamate Levels Affect Group I and II mGluRs in Layer V Pyramidal Neurons of Rat Sensorimotor Cortex  

PubMed Central

Possible functional roles for glutamate that is detectable at low concentrations in the extracellular space of intact brain and brain slices have not been explored. To determine whether this endogenous glutamate acts on metabotropic glutamate receptors (mGluRs), we obtained whole cell recordings from layer V pyramidal neurons of rat sensorimotor cortical slices. Blockade of mGluRs with (+)-?-amino-4-carboxy-?-methyl-benzeacetic acid (MCPG, a general mGluR antagonist) increased the mean amplitude of spontaneous excitatory postsynaptic currents (sEPSCs), an effect attributable to a selective increase in the occurrence of large amplitude sEPSCs. 2S-2-amino-2-(1S,2S-2-carboxycyclopropyl-1-yl)-3-(xanth-9-yl)propanoic acid (LY341495, a group II antagonist) increased, but R(?)-1-amino-2,3-dihydro-1H-indene-1,5-dicarboxylic acid (AIDA) and (RS)-hexyl-HIBO (group I antagonists) decreased sEPSC amplitude, and (R, S)-?-cyclopropyl-4-phosphonophenylglycine (CPPG, a group III antagonist) did not change it. The change in sEPSCs elicited by MCPG, AIDA, and LY341495 was absent in tetrodotoxin, suggesting that it was action potential-dependent. The increase in sEPSCs persisted in GABA receptor antagonists, indicating that it was not due to effects on inhibitory interneurons. AIDA and (S)-3,5-dihy-droxyphenylglycine (DHPG, a group I agonist) elicited positive and negative shifts in holding current, respectively. LY341495 and (2S,2?R,3?R)-2-(2?,3?-dicarboxycyclopropyl)glycine (DCG-IV, a group II agonist) elicited negative and positive shifts in holding current, respectively. The AIDA and LY341495 elicited currents persisted in TTX. Finally, in current clamp, LY341495 depolarized cells by ~2 mV and increased the number of action potentials to a given depolarizing current pulse. Thus ambient levels of glutamate tonically activate mGluRs and regulate cortical excitability. PMID:12626613




Petroleum formation during serpentinization: the evidence of trace elements  

NASA Astrophysics Data System (ADS)

An organic source of petroleum formation is well attested by many biomarkers. This need not, however, exclude contribution from inorganic sources. During serpentinization, in the absence of free oxygen, oxidation of bivalent Fe to magnetite breaks up the water molecule, generating hydrogen and creating one of the most reducing environments near the Earth's surface (Janecky & Seyfried, 1986). Szatmari (1989) proposed that some petroleum forms at plate boundaries by Fischer-Tropsch-type synthesis over serpentinizing peridotites and suggested that Ni, an element rare in the continental crust but important in both petroleum and the mantle, may be indicative of such a source. Recently, Holm and Charlou (2001) observed hydrocarbon formation by Fischer-Tropsch-type synthesis over serpentinizing peridotites of the Mid-Atlantic Ridge. To test whether the relative amounts of other trace elements in petroleum are in agreement with a serpentinizing source, we analyzed by internally coupled plasma-mass spectroscopy (ICP-MS) 22 trace elements in 68 oils sampled in seven sedimentary basins throughout Brazil. We found that trace elements in the oils correlate well with mantle peridotites and reflects the process of hydrothermal serpentinization during continental breakup. Four groups may be distinguished. In serpentinites, trace elements of the first group, Ti, Cr, Mn, and Fe, are largely retained in low-solubility magnetite and other spinels formed during serpentinization or inherited from the original peridotites. In the oils, when normalized to mantle peridotites, these elements are at relatively low levels, about 10,000 times less than their abundances in mantle peridotites, reflecting their low availability from stable minerals. In contrast, trace elements of the second group, which includes V, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Ba, La, Ce, and Nd, pass during serpentinization mostly into serpentine minerals or solution. In the oils, when normalized to mantle peridotites, these elements are at higher levels than those of the first group, about 300 times less than their abundances in mantle peridotites, reflecting their higher availability during serpentinization. Within both groups, trace metal ratios and A/(A+B) type proportionalities in the oils are close to mantle peridotites. V behaves somewhat differently: in lacustrine sequences V contents in the oils are low and the ratios of V to other elements of the second group are mantle-like, whereas in marine sequences V and its ratios to other trace elements rise by orders of magnitude. Trace elements commonly enriched in formation fluids and hydrothermal brines (Rb, Sr, Ba, Cu, Zn), when normalized to mantle peridotites, are enriched in the oils by about 0.5 order of magnitude relative to other elements of the second group. The third group of elements includes S, Mo, and As. These elements occur in the oils at abundances similar to sea water and are, when normalized to mantle peridotites and Ni, enriched in the oils by several orders of magnitude, indicating sea water reacting with peridotites during sepentinization as their possible source. Finally trace elements of the fourth group, such as Pb and Ag, are enriched in the oils by several orders of magnitude relative to both mantle peridotites and sea water and were presumably mobilized from shales by hydrothermal fluids. References:Holm, N.G. and Charlou, J.L., 2001, EPSL 191, 1-8. Janecky, D.R. and Seyfried, W.E., 1986, Geochim. Cosmochim. Acta 50, 1357-1378. Szatmari, P., 1989, AAPG Bull. 73, 989-998.

Szatmari, P.; Fonseca, T. C.; Miekeley, N. F.



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.



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

SciTech Connect

Droplet epitaxy is an important method to produce epitaxial semiconductor quantum dots (QDs). Droplet epitaxy of III-V QDs comprises group III elemental droplet deposition and the droplet crystallization through the introduction of group V elements. Here, we report that, in the droplet epitaxy of InAs/GaAs(001) QDs using metal-organic chemical vapor deposition, significant elemental diffusion from the substrate to In droplets occurs, resulting in the formation of In(Ga)As crystals, before As flux is provided. The supply of As flux suppresses the further elemental diffusion from the substrate and promotes surface migration, leading to large island formation with a low island density.

Chen, Z. B.; Chen, B.; Wang, Y. B.; Liao, X. Z., E-mail: [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Lei, W. [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, WA 6009 (Australia); Tan, H. H.; Jagadish, C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Zou, J. [Materials Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD 4072 (Australia); Ringer, S. P. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia)



K and L X-ray production cross sections and intensity ratios of rare-earth elements for proton impact in the energy range 20–25 MeV  

Microsoft Academic Search

The K?1, K?2, K?1, K?2, and the L?, L?, L? and L? X-ray production (XRP) cross sections and the relative intensity ratios for seven rare-earth elements with 60?Z?70 have been measured for 20, 22 and 25 MeV proton impact. The experimental data on the L-shell XRP cross sections for high energy proton impact have been reported for the first time.

M. Hajivaliei; Sanjiv Puri; M. L Garg; D. Mehta; A. Kumar; S. K Chamoli; D. K Avasthi; A. Mandal; T. K Nandi; K. P Singh; Nirmal Singh; I. M Govil



L-Shell X-ray production cross-sections by impact of 5.0 to 7.5 MeV 10B 2+ ions on selected rare earth elements  

Microsoft Academic Search

L-shell X-ray production cross-sections by 5.0 to 7.5 MeV 10B2+ heavy ion impact on selected rare elements (Ce, Nd, Sm, Eu, Dy, Ho, Gd and Yb) were measured. An evaluation is given of the effect of using several databases for the atomic parameters (fluorescence yields and Coster–Kronig probabilities). Moreover, the application of different theories to predict ionization cross-sections, such as

M. Lugo-Licona; J. Miranda



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

NASA Technical Reports Server (NTRS)

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

Adelman, Saul J.



Chemical Elements  

NSDL National Science Digital Library

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

Ms. Schultz