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Sample records for 4f xps core

  1. Ligand field effects on the multiplet structure of the U4f XPS of UO2

    SciTech Connect

    Ilton, Eugene S.; Bagus, Paul S.

    2008-03-01

    Ab initio, fully relativistic four component theory was used to determine atomic and interatomic many-body effects for the 4f X-ray photoelectron spectrum of an embedded UO8-12 cluster representing UO2. Many-body effects were included through the use of configuration interaction wavefunctions that allow the mixing of XPS allowed and XPS forbidden configurations. Charge transfer configurations were not included. This work extends our earlier studies on simulations of the U 4f XPS for the free U4+ cation. While the main XPS features are similar in both cases, ligand field effects changed the multiplet structure in important ways that better simulated experimental data for UO2. Neither initial nor final state covalency significantly reduced the 4f-5f exchange integrals, and the differences between the atom and cluster model was due to ligand field splitting of the 5f band and increased distributions of intensity from XPS allowed to XPS forbidden peaks. The prominent 7 eV satellites associated with UO2 were absent in the simulations, and provides further evidence that these satellites are due to charge transfer and not other interatomic effects.

  2. Theoretical modeling of the uranium 4f XPS for U(VI) and U(IV) oxides

    SciTech Connect

    Bagus, Paul S.; Nelin, Connie J.; Ilton, Eugene S.

    2013-12-28

    A rigorous study is presented of the physical processes related to X-Ray photoelectron spectroscopy, XPS, in the 4f level of U oxides, which, as well as being of physical interest in themselves, are representative of XPS in heavy metal oxides. In particular, we present compelling evidence for a new view of the screening of core-holes that extends prior understandings. Our analysis of the screening focuses on the covalent mixing of high lying U and O orbitals as opposed to the, more common, use of orbitals that are nominally pure U or pure O. It is shown that this covalent mixing is quite different for the initial and final, core-hole, configurations and that this difference is directly related to the XPS satellite intensity. Furthermore, we show that the high-lying U d orbitals as well as the U(5f) orbital may both contribute to the core-hole screening, in contrast with previous work that has only considered screening through the U(5f) shell. The role of modifying the U-O interaction by changing the U-O distance has been investigated and an unexpected correlation between U-O distance and XPS satellite intensity has been discovered. The role of flourite and octahedral crystal structures for U(IV) oxides has been examined and relationships established between XPS features and the covalent interactions in the different structures. The physical views of XPS satellites as arising from shake processes or as arising from ligand to metal charge transfers are contrasted; our analysis provides strong support that shake processes give a more fundamental physical understanding than charge transfer. Our theoretical studies are based on rigorous, strictly ab initio determinations of the electronic structure of embedded cluster models of U oxides with formal U(VI) and U(IV) oxidation states. Our results provide a foundation that makes it possible to establish quantitative relationships between features of the XPS spectra and materials properties.

  3. Determination of the clean 4 f peak shape in XPS for plutonium metal

    NASA Astrophysics Data System (ADS)

    Morrall, P.; Roussel, P.; Jolly, L.; Brevet, A.; Delaunay, F.

    2009-03-01

    Many of the interesting properties observed with plutonium are ascribed to the influence of 5 f electrons, and to the degree of localisation observed within these electrons. Indeed, changes in 5 f localisation are sensitively reflected in the final states observed in core-level photoemission measurements. However, when analysing the 4 f manifold of elemental plutonium, it is essential to obtain spectra without the influence of oxidation, which can easily be misinterpreted as 5 f localisation. The ideal method to extract elemental plutonium 4 f spectra is to remove any influence of oxidation from the 'clean' plutonium data by careful measurement of the oxygen 1 s region, and the subsequent subtraction of the unwanted oxide features. However, in order to achieve this objective it is essential to determine the relative sensitivity factor (RSF) for plutonium 4 f and the precise shape of the 4 f features from plutonium sesqui-oxide. In this paper, we report an experimental determination of the RSF for the plutonium 4 f manifold using experimental data captured from two different Vacuum Generators spectrometers; an ESCALAB Mk II and an ESCALAB 220i.

  4. Theoretical modeling of the uranium 4f XPS for U(VI) and U(IV) oxides

    SciTech Connect

    Bagus, Paul S.; Nelin, Constance J.; Ilton, Eugene S.

    2013-12-28

    X-ray photoelectron spectroscopy (XPS), and in particular the U4f level, has been widely used to elucidate the chemical state of uranium in various materials. In large part, previous experimental work has relied on comparing the U4f spectra of an unknown to some “standard” or using qualitative intuitive judgments on the expected behavior of the primary lines and satellite structures as a function of oxidation state and bonding environment. Such approaches are useful and can be sufficiently robust to make defensible claims. Nonetheless, there is no quantitative understanding of the chemistry and physics that control satellite structures or even the shape of the primary peaks. To address this issue, we used a rigorous, strictly ab initio theoretical approach to investigate the U(4f) XPS of U oxides with formal U(VI) and U(IV) oxidation states. Our theoretical studies are based on the electronic structures of embedded cluster models, where bonding between U and O is explicitly incorporated. We demonstrate that treatment of the many-body character of the cluster wavefunctions is essential to correctly model and interpret the U4f XPS. Here we definitively show that shake configurations, where an electron is transferred from a dominantly O2p bonding orbital into dominantly 5f or 6d antibonding orbitals, are indeed responsible for the major satellite features. Based on this rigorous theoretical framework, it is possible to establish quantitative relationships between features of the XPS spectra and the chemistry of the material.

  5. Pu 4f XPS spectra analyzed in the Anderson impurity model

    SciTech Connect

    Cox, L.E.; Peek, J.M.; Allen, J.W.

    1998-05-09

    X-ray photoemission spectra of the {alpha},{beta},{gamma}, and {delta} phases of Pu have been analyzed using the Gunnarsson-Schonhammer implementation of the Anderson impurity model. Changes in the relative intensities of the two spectral features representing mixed f{sup 5} and f{sup 6} final states are in reasonable agreement with the model`s predictions. The coulomb terms, U{sub ff} and U{sub fc}, are quite consistent with those derived from atomic and LDA calculations. Multiplet structure, which agrees with atomic calculations for 4f{sup 13}5f{sup 5}, strongly suggests 5f localization in the final state.

  6. Characterization of Core Samples from a Hardened Crust Layer in Tank 4F

    SciTech Connect

    Hay, M. L.

    2005-09-28

    Waste removal operations in Tank 4F are scheduled to begin in late 2005 to provide material for Sludge Batch 5. Mining/probing operations to support installation of submersible mixer pumps encountered a hard layer of material at {approx}45'' to 50'' from the bottom of the tank. Attempts at penetrating the hard layer using a manual mining tool in several different risers were not successful. A core-sampling tool was used to obtain samples of the hard crust layer in Tank 4F for characterization. Three 12'' core samples and a dip sample of the supernate near the surface of the hard layer were sent to Savannah River National Laboratory (SRNL) for characterization. X-ray Diffraction (XRD) results for the crystalline solids from both sample FTF-434 and FTF-435 identifies the major component of both samples as Burkeite (Na{sub 6}(CO{sub 3})(SO{sub 4}){sub 2}). All of the other data collected on the crystalline solids from the Tank 4F core samples support this conclusion. The conditions in Tank 4F for the last twenty years have been ideal for Burkeite formation. The tank has been largely undisturbed with a tank temperature consistently above 30 C, a carbonate to sulfate molar ratio in the supernate conducive to Burkeite formation, and slow evaporation of the supernate phase. Thermodynamic modeling and the results of a Burkeite solubility test confirm that a ratio of 1:1:12 for the volumes of Burkeite solids, supernate, and inhibited water will dissolve all of the Burkeite. These ratios could be used to remove the 6'' layer of Burkeite from Tank 4F with no mixing. However, the thermodynamic modeling and the solubility test neglect the sludge layer beneath the Burkeite crust in Tank 4F. Settled sludge in Savannah River Site (SRS) high-level waste tanks usually contains greater than 75% interstitial supernate by volume. If the supernate in the sludge layer should mix into the solution used to dissolve the Burkeite, significantly more inhibited water would be needed to

  7. Contribution of the 4 f -core-excited states in determination of atomic properties in the Promethium Isoelectronic Sequence

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, Peter; Safronova, U. I.; Safronova, A. S.

    2014-05-01

    The atomic properties of Pm-like ions were comprehensively studied using relativistic atomic codes with the main emphasis on W ion. Excitation energies of the 4f14 nl (with nl = 5 s , 6 s , 5 p , 6 p , 5 d , 6 d , and 5 f) states in Pm-like ions with nuclear charge Z ranging from 74 to 100 are evaluated within the framework of relativistic many-body theory (RMBPT). First- and second-order Coulomb energies and first- and second-order Breit corrections to the energies are calculated. The important question of what is the ground state in Pm-like ions was answered. Properties of the 4 f -core-excited states are evaluated using the multiconfiguration relativistic Hebrew University Lawrence Livermore Atomic Code (HULLAC code) and the Hartree-Fock-Relativistic method (COWAN code). Our large scale calculations includes the following set of configurations: 4f14 5 s , 4f14 5 p , 4f13 5s2 , 4f13 5p2 , 4f13 5 s 5 p , 4f12 5s2 5 p , 4f12 5 s 5p2 , and 4f12 5p3 . Excitation energies, transition rates, and lifetimes in Pm-like tungsten are evaluated with additional inclusion of the 4f11 5s2 5p2 , 4f11 5 s 5p3 , 4f10 5s2 5p3 , and 4f10 5 s 5p4 configurations. Wavelengths of the 5 s - 5 p transitions are obtained by the COWAN, HULLAC, and RMBPT codes. This research was sponsored by DOE under the OFES grant DE-FG02-08ER54951 and in part by NNSA Cooperative Agreement DE-NA0001984. Work at Lawrence Livermore National Lab. was performed under the auspices of DOE under Contract DE-AC52-07NA27344.

  8. A first-principles core-level XPS study on the boron impurities in germanium crystal

    NASA Astrophysics Data System (ADS)

    Yamauchi, Jun; Yoshimoto, Yoshihide; Suwa, Yuji

    2013-12-01

    We systematically investigated the x-ray photoelectron spectroscopy (XPS) core-level shifts and formation energies of boron defects in germanium crystals and compared the results to those in silicon crystals. Both for XPS core-level shifts and formation energies, relationship between defects in Si and Ge is roughly linear. From the similarity in the formation energy, it is expected that the exotic clusters like icosahedral B12 exist in Ge as well as in Si.

  9. A first-principles core-level XPS study on the boron impurities in germanium crystal

    SciTech Connect

    Yamauchi, Jun; Yoshimoto, Yoshihide; Suwa, Yuji

    2013-12-04

    We systematically investigated the x-ray photoelectron spectroscopy (XPS) core-level shifts and formation energies of boron defects in germanium crystals and compared the results to those in silicon crystals. Both for XPS core-level shifts and formation energies, relationship between defects in Si and Ge is roughly linear. From the similarity in the formation energy, it is expected that the exotic clusters like icosahedral B12 exist in Ge as well as in Si.

  10. Transitions between the 4 f -core-excited states in Ir16+, Ir17+, and Ir18+ ions for clock applications

    NASA Astrophysics Data System (ADS)

    Safronova, U. I.; Flambaum, V. V.; Safronova, M. S.

    2016-05-01

    Iridium ions near 4 f - 5 s level crossings are the leading candidates for a new type of atomic clocks with a high projected accuracy and a very high sensitivity to the temporal variation of the fine structure constant α. To identify spectra of these ions in experiment accurate calculations of the spectra and electromagnetic transition probabilities should be performed. Properties of the 4 f -core-excited states in Ir16+, Ir17+, and Ir18+ ions are evaluated using relativistic many-body perturbation theory and Hartree-Fock-Relativistic method (COWAN code). We evaluate excitation energies, wavelengths, oscillator strengths, and transition rates. Our large-scale calculations included the following set of configurations: 4f14 5 s , 4f14 5 p , 4f13 5s2 , 4f13 5p2 , 4f13 5 s 5 p , 4f12 5s2 5 p , and 4f12 5 s 5p2 in Pm-like Ir16+ ; 4f14 , 4f13 5 s , 4f13 5 p , 4f12 5s2 , 4f12 5 s 5 p , and 4f12 5p2 in Nd-like Ir17+; and 4f13 , 4f12 5 s , 4f12 5 p , 4f11 5s2 , and 4f11 5 s 5 p in Pr-like Ir18+. The 5 s - 5 p transitions are illustrated by the synthetic spectra in the 180 - 200 Å range. Large contributions of magnetic-dipole transitions to lifetimes of low-lying states in the region 2.5 Ry.

  11. Primary excitation spectra in XPS and AES of Cu, CuO: Relative importance of surface and core hole effects

    NASA Astrophysics Data System (ADS)

    Pauly, N.; Tougaard, S.

    2015-11-01

    Quantitative interpretation of structures observed in XPS and AES requires models to correct for various physical processes involved. Besides the initial excitation process in XPS and AES, the measured spectrum is affected by three additional effects: the corehole(s), transport to the surface region and passage through the surface and vacuum regions. These three effects can be calculated by the QUEELS-XPS software (Quantitative analysis of Electron Energy Losses at Surfaces) in terms of energy-differential inelastic electron scattering cross sections. From this and the QUASES software (Quantitative Analysis of Surfaces by Electron Spectroscopy), background contributions and primary excitation spectra are obtained for various transitions (Cu 2p from Cu or CuO and Cu L3M23M23) and we investigate the separate effect of bulk, surface, and core hole(s) excitations. We show that the shape of the XPS and AES primary spectra and background contributions are modified slightly by surface effects and very strongly by core hole(s) effects. For metals, the intrinsic excitations give rise to a prominent spike in the background close to the XPS-peak energy. This spike will be much reduced for wide band gap insulators. Moreover our method gives an easy procedure to obtain the true primary excitation spectra for XPS and AES.

  12. Characterization of YBa 2Cu 3O x using core- and valence-level XPS

    NASA Astrophysics Data System (ADS)

    Brundle, C. R.; Fowler, D. E.

    1993-12-01

    Hundreds of papers have been published involving the photoelectron spectroscopy of the high- Tc superconducting oxides since 1987. The early work, originally on bulk-sintered material, sputtered films, and later on "single crystals", concentrated on finding "unusual" features in valence- or core-level spectra to relate to electronic structure effects which might explain the superconducting mechanism. The majority of this work has not adequately taken into account the facts that (a) photoemission probes only the top few monolayers of material, and (b) in many cases the top few layers are completely unrepresentative of the bulk material. This is particularly true for YBa 2Cu 3O x, where the surface is extremely reactive, unstable, and prone to contaminating phases, even when prepared under UHV conditions. This has led to a flood of misinformation concerning the true characteristic spectra of this material and their interpretation. In this paper, we present core- and valence-level XPS for YBa 2Cu 3O x single-crystal, bulk-sintered, and thin-film samples, and show that, when artifacts are eliminated, the characteristic spectra are the same, to first order, and easily allow distinction of surfaces consisting of the genuine orthorhombic phase ( x > 6.4) from those with the non-superconducting tetragonal phase ( x<6.4) or contaminant or reaction-product phases. With this information, it is possible to eliminate much of the previous literature discussion and also to follow the material changes occuring, for instance, during annealing, adsorption and reaction. We then discuss some detailed interpretations, including the DOS observed at and near EF, the explanations for the ˜1.5 eV chemical shift in Ba core-level BE between orthorhombic and tetragonal forms, and the implications of the very low O(1s) BE of the orthorhombic form.

  13. The influence of oxygen adsorption on the NEXAFS and core-level XPS spectra of the C{sub 60} derivative PCBM

    SciTech Connect

    Brumboiu, Iulia Emilia Eriksson, Olle; Brena, Barbara; Ericsson, Leif; Hansson, Rickard; Moons, Ellen

    2015-02-07

    Fullerenes have been a main focus of scientific research since their discovery due to the interesting possible applications in various fields like organic photovoltaics (OPVs). In particular, the derivative [6,6]-phenyl-C{sub 60}-butyric acid methyl ester (PCBM) is currently one of the most popular choices due to its higher solubility in organic solvents compared to unsubstituted C{sub 60}. One of the central issues in the field of OPVs is device stability, since modules undergo deterioration (losses in efficiency, open circuit voltage, and short circuit current) during operation. In the case of fullerenes, several possibilities have been proposed, including dimerization, oxidation, and impurity related deterioration. We have studied by means of density functional theory the possibility of oxygen adsorption on the C{sub 60} molecular moiety of PCBM. The aim is to provide guidelines for near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) measurements which can probe the presence of atomic or molecular oxygen on the fullerene cage. By analysing several configurations of PCBM with one or more adsorbed oxygen atoms, we show that a joint core level XPS and O1s NEXAFS investigation could be effectively used not only to confirm oxygen adsorption but also to pinpoint the bonding configuration and the nature of the adsorbate.

  14. Quantitative analysis of satellite structures in XPS spectra of gold and silver

    NASA Astrophysics Data System (ADS)

    Pauly, N.; Yubero, F.; Tougaard, S.

    2016-10-01

    Identification of specific chemical states and local electronic environments at surfaces by X-ray photoelectron spectroscopy (XPS) is often difficult because it is not straightforward to quantitatively interpret the shape and intensity of shake-up structures that originate from the photoexcitation process. Indeed the shape and intensity of measured XPS structures are strongly affected by both extrinsic excitations due to electron transport out of the surface and intrinsic excitations induced by the sudden creation of the static core hole. These processes must be taken into account to quantitatively extract, from experimental XPS, the primary excitation spectrum of the considered transition which includes all effects that are part of the initial photo-excitation process, i.e. lifetime broadening, spin-orbit coupling, and multiplet splitting. It was previously shown [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17] that both extrinsic and intrinsic excitations could be included in an effective energy-differential inelastic electron scattering cross section for XPS which is then convoluted with the primary excitation spectrum to model the full XPS spectrum. This method can thus be applied to determine the primary excitation spectrum from any XPS spectrum. We use this approach in the present paper to determine the Au 4f and Ag 3d photoemission spectra from pure metals. We observe that characteristic energy loss features of the XPS spectra are not only due to photoelectron energy losses. We thus prove the existence of a double shake-up process characterized by a 4d → 5s/5p transition for Ag and a 5d → 6s/6p transition for Au. We finally accurately quantify the energy position and intensity of these shake-up peaks.

  15. THEORY FOR THE XPS OF ACTINIDES

    SciTech Connect

    Bagus, Paul S.; Ilton, Eugene S.

    2013-08-01

    Two aspects of the electronic structure of actinide oxides that significantly affect the XPS spectra are described; these aspects are also important for the materials properties of the oxides. The two aspects considered are: (1) The spin-orbit coupling of the open 5f shell electrons in actinide cations and how this coupling affects the electronic structure. And, (2) the covalent character of the metal oxygen interaction in actinide compounds. Because of this covalent character, there are strong departures from the nominal oxidation states that are significantly larger in core-hole states than in the ground state. The consequences for the XPS of this covalent character are examined. A proper understanding of the way in which they influence the XPS makes it possible to use the XPS to correctly characterize the electronic structure of the oxides.

  16. An empirical and theoretical investigation of the intensities of 4f-4f electronic transitions

    SciTech Connect

    Devlin, M.T.

    1987-01-01

    The intensities of certain lanthanide 4f-4f electronic transitions exhibit extraordinary sensitivity to the ligand environment near a lanthanide ion, and empirical and theoretical investigations of these 4f-4f electric-dipole transitions are reported herein. From these studies, the mechanistic basis of 4f-4f electric-dipole transition intensities are evaluated. Additionally, correlations between the structure of lanthanide-ligand complexes and empirically observed electronic transition intensities are developed. The general applicability and utility of these spectra-structure correlations are also evaluated. The influence of the ligand environment of 4f-4f transition intensities is investigated by measuring the absorption spectra of a series of well-characterized neodymium (Nd{sup 3+}), holmium (Ho{sup 3+}) and erbium (Er{sup 3+})-ligand complexes. Trends in the absorption intensity spectra of these lanthanide complexes are related to specific structural features of each complex. The empirically observed spectral trends are evaluated by theoretically investigation the mechanism by which 4f-4f electric-dipole transitions occur. Two separate models of 4f-4f electronic transitions, the static - coupling and the dynamic - coupling models, are incorporated into the general Judd-Ofelt intensity theory. Using these two models, theoretical calculations of 4f-4f electronic transition intensities are performed. The results of these calculations are in good agreement with empirically observed 4f-4f electronic transition intensities, and they are useful in rationalizing the observed spectra-structure correlations.

  17. Atomic Near-Degeneracy For Photoemission: Generality of 4f Excitations

    SciTech Connect

    Bagus, Paul S.; Broer, R.; Ilton, Eugene S.

    2008-09-01

    In a previous study of the 3s X-ray photoelectron spectra, XPS, of Mn, we identified a new intra-atomic many-body effect that lead to an ~50% increase in the predicted exchange splitting of the main high spin and low spin XPS peaks. The new many-body effect involved the promotion of one electron from the M shell, 3s, 3p, and 3d, into a 4f orbital and a redistribution of the remaining electrons over the M shell orbitals; of particular importance were frustrated Auger configurations. FAC’s where the 3s shell was filled. In the present work, we demonstrate the general importance of these 4f FAC’s by showing that they are of comparable importance for increasing the 3s exchange splitting in Ni as they were in Mn.

  18. Comparison of magnetic linear dichroism in 4f photoemission and 4d{endash}4f photoemission from Gd on Y(0001)

    SciTech Connect

    Gammon, W.J.; Mishra, S.R.; Pappas, D.P.; Goodman, K.W.; Tobin, J.G.; Schumann, F.O.; Willis, R.; Denlinger, J.D.; Rotenberg, E.; Warwick, A.; Smith, N.V.

    1997-05-01

    Magnetic linear dichroism (MLD) in 4d{endash}4f resonant and 4f nonresonant photoemission (PE) is studied from thin epitaxial gadolinium films. In an angle resolved and high-energy resolution mode, experiments were conducted with the electric-field vector of the incident light perpendicular to the sample magnetization. Our results show a significant difference in behavior of MLD in resonant PE as compared to that in nonresonant PE. Off-resonance, the MLD signal is dominated by a negative feature at the low binding energy side of the peak. Near the 4d{endash}4f resonance maximum, the MLD displays a plus{endash}minus shape, with a negative signal at the low binding energy side of the 4f peak and a positive signal at the high binding energy side. Analysis of MLD in 4d{endash}4f resonant PE may provide insight into interactions of the 4d core hole with the 4f core level in the intermediate state. {copyright} {ital 1997 American Vacuum Society.}

  19. Electronic structures of Pt-Co and Pt-Ru alloys for CO-tolerant anode catalysts in polymer electrolyte fuel cells studied by EC-XPS.

    PubMed

    Wakisaka, Mitsuru; Mitsui, Satoshi; Hirose, Yoshikazu; Kawashima, Katsura; Uchida, Hiroyuki; Watanabe, Masahiro

    2006-11-23

    CO tolerance at pure Pt, Pt-Co, and Pt-Ru alloys was investigated by X-ray photoelectron spectroscopy combined with an electrochemical cell (EC-XPS) in order to discover a hint for designing higher performance anode catalysts. After the electrochemical stabilization and/or CO adsorption, these electrodes were immediately transferred to the XPS chamber without exposure to air to avoid contamination of the surfaces. It was revealed that alloying with Co or Ru modified the electronic structures of Pt atoms, resulting in a positive core level (CL) shift of Pt 4f(7/2) which could weaken the Pt-CO interaction. For the Pt-Co alloy electrode, the Pt 4f(7/2) CL shift remained after the electrochemical stabilization despite Co dissolution and formation of a Pt skin layer. Changes in surface core level shifts (DeltaSCLSs) induced by CO adsorption were evaluated and related to the CO adsorption energy. The values of DeltaSCLS at these alloys were smaller than that of pure Pt, indicating that Ru and Co are effective elements to weaken the bond strength of Pt-CO. PMID:17107203

  20. Tetranuclear Zn/4f coordination clusters as highly efficient catalysts for Friedel-Crafts alkylation.

    PubMed

    Griffiths, Kieran; Kumar, Prashant; Akien, Geoffrey R; Chilton, Nicholas F; Abdul-Sada, Alaa; Tizzard, Graham J; Coles, Simon J; Kostakis, George E

    2016-06-14

    A series of custom-designed, high yield, isoskeletal tetranuclear Zn/4f coordination clusters showing high efficiency as catalysts with low catalytic loadings in Friedel-Crafts alkylation are described for the first time. The possibility of altering the 4f centers in these catalysts without altering the core topology allows us to further confirm their stability via EPR and NMR, as well to gain insights into the plausible reaction mechanism, showcasing the usefulness of these bimetallic systems as catalysts. PMID:27248829

  1. 77 FR 321 - Section 4(f) Policy Paper

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-04

    ... Federal Highway Administration Section 4(f) Policy Paper AGENCY: Federal Highway Administration (FHWA... draft Section 4(f) Policy Paper that will provide guidance on the procedures the FHWA will follow when... practicable. Background A copy of the proposed Section 4(f) Policy Paper is available for download and...

  2. Plasma-surface interactions of nanoporous silica during plasma-based pattern transfer using C{sub 4}F{sub 8} and C{sub 4}F{sub 8}/Ar gas mixtures

    SciTech Connect

    Hua Xuefeng; Stolz, Christian; Oehrlein, G.S.; Lazzeri, P.; Coghe, N.; Anderle, M.; Inoki, C.K.; Kuan, T.S.; Jiang, P.

    2005-01-01

    We have investigated plasma surface interactions of nanoporous silica (NPS) films with porosities up to 50%, and SiO{sub 2} with C{sub 4}F{sub 8}/Ar discharges used for plasma etching. The pore size was about 2-3 nm for all films. In highly polymerizing plasmas (e.g., pure C{sub 4}F{sub 8} discharges), the porous structure of NPS material favors surface polymerization over etching and porosity-corrected etching rates (CER) were suppressed and lower than SiO{sub 2} etching rate for the same conditions. The etching rates of NPS were dramatically enhanced in ion rich discharges (e.g., C{sub 4}F{sub 8}/90%Ar) and the CER in this case is greater than the SiO{sub 2} etching rate. Both x-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectroscopy (static SIMS) show that fairly thick ({approx}2-3 nm) fluorocarbon layers exist on the NPS surface during C{sub 4}F{sub 8} etching. This layer blocks the direct interaction of ions with the NPS surface and results in a low etching rate. For C{sub 4}F{sub 8}/90%Ar discharges, little fluorocarbon coverage is observed for NPS surfaces and the direct ion surface interaction is significantly enhanced, explaining the enhancement of CER. We can deduce from analysis of angular resolved XPS data that the surface of NPS materials and SiO{sub 2} remain smooth during C{sub 4}F{sub 8} etching. For C{sub 4}F{sub 8}/90%Ar etching, the NPS surfaces became rough. The surface roughening is due to angle-dependent ion etching effects. These surface models were directly verified by the transmission electron microscopy. Depth profiling study of NPS partially etched using C{sub 4}F{sub 8} or C{sub 4}F{sub 8}/90%Ar discharges using dynamic SIMS indicates that the plasma induced modification of NPS was enhanced significantly compared with SiO{sub 2} due to the porous structure, which allows the plasma attack of the subsurface region. The modified layer thickness is related to the overall porosity and dramatically increases for NPS

  3. Magnetic x-ray linear dichroism in resonant and non-resonant Gd 4f photoemission

    SciTech Connect

    Mishra, S.; Gammon, W.J.; Pappas, D.P.

    1997-04-01

    The enhancement of the magnetic linear dichroism in resonant 4f photoemission (MLDRPE) is studied from a 50 monolayer film of Gd/Y(0001). The ALS at beamline 7.0.1 provided the source of linearly polarized x-rays used in this study. The polarized light was incident at an angle of 30 degrees relative to the film plane, and the sample magnetization was perpendicular to the photon polarization. The linear dichroism of the 4f core levels is measured as the photon energy is tuned through the 4d-4f resonance. The authors find that the MLDRPE asymmetry is strongest at the resonance. Near the threshold the asymmetry has several features which are out of phase with the fine structure of the total yield.

  4. Does the 4f-shell contribute to bonding in tetravalent lanthanide halides?

    SciTech Connect

    Ji, Wen-Xin; Xu, Wei; Xiao, Yi; Wang, Shu-Guang

    2014-12-28

    Lanthanide tetrahalide molecules LnX{sub 4} (Ln = Ce, Pr, Tb; X = F, Cl, Br, I) have been investigated by density functional theory at the levels of the relativistic Zero Order Regular Approximation and the relativistic energy-consistent pseudopotentials, using frozen small- and medium-cores. The calculated bond lengths and vibrational frequencies are close to the experimental data. Our calculations indicate 4f shell contributions to bonding in LnX{sub 4}, in particular for the early lanthanides, which show significant overlap between the Ln 4f-shell and the halogen np-shells. The 4f shells contribute to Ln-X bonding in LnX{sub 4} about one third more than in LnX{sub 3}.

  5. The coordination chemistry and magnetism of some 3d–4f and 4f amino-polyalcohol compounds

    PubMed Central

    Sharples, Joseph W.; Collison, David

    2014-01-01

    Triethanolamine, teaH3, and diethanolamine, RdeaH2, 3d–4f and 4f compounds demonstrate an enormous variety in their structure and bonding. This review examines the synthetic strategies to these molecules and their magnetic properties, whilst trying to assess these ligands’ suitability towards new SMMs and magnetic refrigerants. PMID:25009361

  6. The coordination chemistry and magnetism of some 3d-4f and 4f amino-polyalcohol compounds.

    PubMed

    Sharples, Joseph W; Collison, David

    2014-02-01

    Triethanolamine, teaH3, and diethanolamine, RdeaH2, 3d-4f and 4f compounds demonstrate an enormous variety in their structure and bonding. This review examines the synthetic strategies to these molecules and their magnetic properties, whilst trying to assess these ligands' suitability towards new SMMs and magnetic refrigerants. PMID:25009361

  7. 4f electron delocalization and volume collapse in praseodymium metal

    SciTech Connect

    Bradley, Joseph A.; Moore, Kevin T.; Lipp, Magnus J.; Mattern, Brian A.; Pacold, Joseph I.; Seidler, Gerald T.; Chow, Paul; Rod, Eric; Xiao, Yuming; Evans, William J.

    2012-04-17

    We study the pressure evolution of the 4f electrons in elemental praseodymium metal compressed through several crystallographic phases, including the large volume-collapse transition at 20 GPa. Using resonant x-ray emission, we directly and quantitatively measure the development of multiple electronic configurations with differing 4f occupation numbers, the key quantum observable related to the delocalization of the strongly correlated 4f electrons. These results provide a high-fidelity test of prior predictions by dynamical mean-field theory, and support the hypothesis of a strong connection between electronic and structural degrees of freedom at the volume-collapse transition.

  8. Optical 4 f-4 f transitions in multiferroic HoMnO3

    NASA Astrophysics Data System (ADS)

    Loshkareva, N. N.; Moskvin, A. S.; Balbashov, A. M.

    2009-05-01

    In the absorption spectra of the hexagonal single-crystal manganite HoMnO3 in the paramagnetic ferroelectric state, lines near 1.1 and 2.0 μm were observed associated with the transitions 5 I 8 → 5 I 6 and 5 I 8 → 5 I 7, respectively, within the 4 f 10 configuration of the Ho3+ ion. At T = 80 K, to the 5 I 8 → 5 I 7 transition corresponds one band at 1.9 μm for both polarizations E ∥ c and E ⊥ c. As the temperature increases from 80 to 293 K, a low-energy band with a peak at 2.04 μm for E ⊥ c and a peak at 2.07 μm for E ∥ c arises associated with transitions from an excited Stark level of the ground 5 I 8 multiplet to the Stark levels of the 5 I 7 multiplet and with an increase in the population of the initial Stark level, the energy of which is ˜100 K.

  9. NEXAFS and XPS studies of nitrosyl chloride.

    PubMed

    Schio, Luca; Li, Cui; Monti, Susanna; Salén, Peter; Yatsyna, Vasyl; Feifel, Raimund; Alagia, Michele; Richter, Robert; Falcinelli, Stefano; Stranges, Stefano; Zhaunerchyk, Vitali; Carravetta, Vincenzo

    2015-04-14

    The electronic structure of nitrosyl chloride (ClNO) has been investigated in the gas phase by X-ray Photoelectron (XPS) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy at the Cl 2p, Cl 2s, N 1s and O 1s edges in a combined experimental and theoretical study. The theoretical calculations at different levels of approximation predict ionization potential values in good agreement with the experimental data and allow us to assign the main features of the absorption spectra. An unexpected failure of the density functional model is, however, observed in the calculation of the Cl 2s binding energy, which is related to a large self-interaction error. Largely different photoabsorption cross-section patterns are experimentally observed in core excitations from the investigated quantum shells (n = 1, 2). This finding is confirmed by the oscillator strength distributions calculated at different absorption edges; in the case of the n = 2 shell the bands below the threshold are extremely weak and most of the absorption intensity is due to excitations in the continuum. PMID:25754872

  10. XPS Study of SiO2 and the Si/SiO2 Interface

    NASA Technical Reports Server (NTRS)

    Grunthaner, F. J.; Grunthaner, P. J.; Vasquez, R. P.; Lewis, B. F.; Maserjian, J.; Madhukar, A.

    1982-01-01

    X-ray photoelectron spectroscopy (XPS) is analytical technique for understanding electronic structure of atoms close to surface in solids, in preference to bulk structure of material. Study found evidence for core-level chemical shifts arising from changes in local structural environment in amorphous SiO2 and at Si/SiO2 interface. Observed XPS spectra may be understood as sequential convolution of several functions, each with well-defined physical interpretation.

  11. Os layers spontaneously deposited on the Pt(111) electrode : XPS, STM and GIF-XAS study.

    SciTech Connect

    Rhee, C. K.; Wakisaka, M.; Tolmachev, Y.; Johnston, C.; Haasch, R.; Attenkofer, K.; Lu, G. Q.; You, H.; Wieckowski, A.; Univ. of Illinois Champaigh-Urbana

    2003-01-01

    Scanning tunneling microscopy (STM) characterized adlayers of spontaneously deposited osmium on a Pt(111) electrode were investigated using ex-situ X-ray photoemission spectroscopy (XPS) and in-situ grazing incidence fluorescence X-ray absorption spectroscopy (GIF-XAS). After a single spontaneous deposition, monoatomic (or nearly monoatomic) nanoislands of osmium are formed. The island diameter varies from 2 to 5 nm depending on the Os coverage, which in turn is adjusted by varying the concentration of the Os precursor salt (OsCl3) in the deposition bath and/or by the deposition time. XPS reveals three oxidation states: a metallic Os (the 4f7/2 core level binding energy of 50.8 eV), Os(IV) (51.5 eV) and Os(VIII) (52.4 eV). The metallic osmium exists at potentials below 500 mV (vs. RHE) while above 500 mV osmium is oxidized to Os(IV). Electrodissolution of osmium begins above 900 mV and occurs simultaneously with platinum oxidation. At ca. 1200 mV V versus the RHE reference, the oxidation state of some small amounts of osmium that survive dissolution is the Os(VIII). We demonstrate, for the first time, that mixed or odd valencies of osmium exist on the platinum surface at potentials higher that 800 mV. In-situ GIF-XAS measurements of an Os LIII edge also reveal the presence of three Os oxidation states. Namely, below the electrode potential of 400 mV, the X-ray fluorescent energy at maximum absorption is 10.8765 keV, and is characteristic of the metallic Os. In the potential range between 500 and 1000 mV this energy is gradually shifted to higher values, assignable to higher valencies of osmium, like Os(IV). This tendency continues to higher potentials consistent with the third, highly oxidized osmium form present, most likely Os(VIII). The variation of the 'raw edge jump height' of Os with the electrode potential, which is equivalent to a drop in osmium surface concentration, demonstrates that the electrochemical stripping of Os begins below 1.0 V versus RHE, as

  12. Two transcription factors, Pou4f2 and Isl1, are sufficient to specify the retinal ganglion cell fate

    PubMed Central

    Wu, Fuguo; Kaczynski, Tadeusz J.; Sethuramanujam, Santhosh; Li, Renzhong; Jain, Varsha; Slaughter, Malcolm; Mu, Xiuqian

    2015-01-01

    As with other retinal cell types, retinal ganglion cells (RGCs) arise from multipotent retinal progenitor cells (RPCs), and their formation is regulated by a hierarchical gene-regulatory network (GRN). Within this GRN, three transcription factors—atonal homolog 7 (Atoh7), POU domain, class 4, transcription factor 2 (Pou4f2), and insulin gene enhancer protein 1 (Isl1)—occupy key node positions at two different stages of RGC development. Atoh7 is upstream and is required for RPCs to gain competence for an RGC fate, whereas Pou4f2 and Isl1 are downstream and regulate RGC differentiation. However, the genetic and molecular basis for the specification of the RGC fate, a key step in RGC development, remains unclear. Here we report that ectopic expression of Pou4f2 and Isl1 in the Atoh7-null retina using a binary knockin-transgenic system is sufficient for the specification of the RGC fate. The RGCs thus formed are largely normal in gene expression, survive to postnatal stages, and are physiologically functional. Our results indicate that Pou4f2 and Isl1 compose a minimally sufficient regulatory core for the RGC fate. We further conclude that during development a core group of limited transcription factors, including Pou4f2 and Isl1, function downstream of Atoh7 to determine the RGC fate and initiate RGC differentiation. PMID:25775587

  13. XPS characterization of iron Fischer-Tropsch catalysts

    SciTech Connect

    Kuivila, C.S.; Stair, P.C.; Butt, J.B.

    1986-04-01

    Analysis of Fe(2p) XPS and iron Auger spectra, combined with C(1s) XPS measurements, provides a valuable technique for studying the compositional behavior of Fischer-Tropsch catalysts. The extent of catalyst oxidation during synthesis at high conversions may be estimated in terms of the area contribution of oxide phases to the Fe(2p) spectrum. Similarities between the metal and carbide core level spectra are likely to complicate the determination of these phases when oxides are present. Analysis of the metal and carbide contributions to the iron Auger spectrum provides an alternate method for monitoring surface carbide formation during low conversion synthesis. The ''surface compositions'' obtained in this manner are at best semi-quantitative, since the contribution of a particular phase to the XPS or Auger spectrum will depend on both the amount and distribution of that phase within the detected volume. In spite of this, the spectrum fitting technique should prove to be useful in characterizing the time and conversion dependent nature of the active catalyst surface.

  14. XPS quantification of the hetero-junction interface energy

    NASA Astrophysics Data System (ADS)

    Ma, Z. S.; Wang, Yan; Huang, Y. L.; Zhou, Z. F.; Zhou, Y. C.; Zheng, Weitao; Sun, Chang Q.

    2013-01-01

    We present an approach for quantifying the heterogeneous interface bond energy using X-ray photoelectron spectroscopy (XPS). Firstly, from analyzing the XPS core-level shift of the elemental surfaces we obtained the energy levels of an isolated atom and their bulk shifts of the constituent elements for reference; then we measured the energy shifts of the specific energy levels upon interface alloy formation. Subtracting the referential spectrum from that collected from the alloy, we can distil the interface effect on the binding energy. Calibrated based on the energy levels and their bulk shifts derived from elemental surfaces, we can derive the bond energy, energy density, atomic cohesive energy, and free energy at the interface region. This approach has enabled us to clarify the dominance of quantum entrapment at CuPd interface and the dominance of polarization at AgPd and BeW interfaces, as the origin of interface energy change. Developed approach not only enhances the power of XPS but also enables the quantification of the interface energy at the atomic scale that has been an issue of long challenge.

  15. Structure-based description of a step-by-step synthesis of homo- and heterodinuclear (4f, 4f ') lanthanide complexes.

    PubMed

    Costes, Jean-Pierre; Dahan, Françoise; Nicodème, Franck

    2003-10-01

    The stepwise course of the synthesis of homo- (4f, 4f) and heterodilanthanide (4f, 4f ') complexes has been investigated through structural determination of the intermediate and final products occurring in the process. In the first step, the tripodal ligand H(3)L is reacted with Ln(NO(3))(3) x 5H(2)O to give a complex (H(3)L)Ln(NO(3))(3) in which the ligand does exist in a zwitterionic form. This unexpected feature has been definitely supported by a structural determination performed on a closely related complex (HL')(3)Ln(NO(3))(3) (1). These species are fairly stable and may be isolated. In basic medium, (H(3)L)Ln(NO(3))(3) is deprotonated to yield a neutral LLn complex crystallized as LLnNaClO(4) (2), the lanthanide ion being linked to the inner N(4)O(3) coordination site of the ligand. Finally, addition of Ln'(NO(3))(3) x 5H(2)O (Ln' being similar or different from Ln) to the LLn complex yields the desired homo- or heterodinuclear LLnLn'(NO(3))(3) complex 3, where the Ln' ion is coordinated to the outer O(3)O(3) coordination site of the tripodal ligand. Complex 1 (Ln = La) crystallizes in the triclinic space group P1 (No. 2): a = 11.1883(7) A, b = 11.8993(9) A, c = 16.4197(10) A, alpha = 81.900 (6) degrees, beta = 79.406(5) degrees, gamma = 79.470(6) degrees, V = 2099.5(2) A(3), Z = 2. Complex 2 (Ln = Eu) crystallizes in the monoclinic space group P2(1)/n (No. 14): a = 13.6333(13) A, b = 15.3799(12) A, c = 17.1473(13) A, beta = 111.283(10) degrees, V = 3350.2(5) A(3), Z = 4. Complex 3 (Ln = Ln' = Dy) crystallizes in the trigonal space group R3 (No. 148) with a = b = 23.847(3) A, c = 42.982(2) A, V = 21168(4) A(3), Z = 18. Complex 3 possesses a Dy(O(phenoxo))(3)Dy core, and a nitrato anion has been replaced by a eta(2)-chelated o-vanillin anion. We did not succeed in obtaining crystals of any of the heterodinuclear LLnLn'(NO(3))(3) entities, but their existence was unambiguously confirmed by positive fast atom bombardment mass spectrometry experiments. PMID

  16. Synchrotron-radiation XPS analysis of ultra-thin silane films: Specifying the organic silicon

    NASA Astrophysics Data System (ADS)

    Dietrich, Paul M.; Glamsch, Stephan; Ehlert, Christopher; Lippitz, Andreas; Kulak, Nora; Unger, Wolfgang E. S.

    2016-02-01

    The analysis of chemical and elemental in-depth variations in ultra-thin organic layers with thicknesses below 5 nm is very challenging. Energy- and angle-resolved XPS (ER/AR-XPS) opens up the possibility for non-destructive chemical ultra-shallow depth profiling of the outermost surface layer of ultra-thin organic films due to its exceptional surface sensitivity. For common organic materials a reliable chemical in-depth analysis with a lower limit of the XPS information depth z95 of about 1 nm can be performed. As a proof-of-principle example with relevance for industrial applications the ER/AR-XPS analysis of different organic monolayers made of amino- or benzamidosilane molecules on silicon oxide surfaces is presented. It is demonstrated how to use the Si 2p core-level region to non-destructively depth-profile the organic (silane monolayer) - inorganic (SiO2/Si) interface and how to quantify Si species, ranging from elemental silicon over native silicon oxide to the silane itself. The main advantage of the applied ER/AR-XPS method is the improved specification of organic from inorganic silicon components in Si 2p core-level spectra with exceptional low uncertainties compared to conventional laboratory XPS.

  17. XPS Study of Thermally Evaporated Ge-Sb-Te Amorphous Thin Films

    SciTech Connect

    Kumar, Sandeep; Singh, Digvijay; Thangaraj, R.

    2011-12-12

    Amorphous thin films were prepared from the bulk composition of Ge{sub 22}Sb{sub 22}Te{sub 56}(GST) alloy by thermal evaporation in good vacuum condition. The amorphous nature of as-deposited films was checked with x-ray diffraction (XRD) studies. X-ray photoelectron spectroscopy (XPS) has been used to determine the binding energies of the core electrons in amorphous thin GST films. In XPS, we performed the survey scan from the binding energy (BE) range from 0-1100 eV and core level spectra of Ge 3d, Sb 3d and Te 3d.

  18. Deduction of the chemical state and the electronic structure of Nd{sub 2}Fe{sub 14}B compound from X-ray photoelectron spectroscopy core-level and valence-band spectra

    SciTech Connect

    Wang, Jing; Liang, Le; Zhang, Lanting E-mail: lmsun@sjtu.edu.cn; Sun, Limin E-mail: lmsun@sjtu.edu.cn; Hirano, Shinichi

    2014-10-28

    Characterization of chemical state and electronic structure of the technologically important Nd{sub 2}Fe{sub 14}B compound is attractive for understanding the physical nature of its excellent magnetic properties. X-ray photoelectron spectroscopy (XPS) study of such rare-earth compound is important and also challenging due to the easy oxidation of surface and small photoelectron cross-sections of rare-earth 4f electrons and B 2p electrons, etc. Here, we reported an investigation based on XPS spectra of Nd{sub 2}Fe{sub 14}B compound as a function of Ar ion sputtering time. The chemical state of Fe and that of B in Nd{sub 2}Fe{sub 14}B compound can be clearly determined to be 0 and −3, respectively. The Nd in Nd{sub 2}Fe{sub 14}B compound is found to have the chemical state of close to +3 instead of +3 as compared with the Nd in Nd{sub 2}O{sub 3}. In addition, by comparing the valence-band spectrum of Nd{sub 2}Fe{sub 14}B compound to that of the pure Fe, the contributions from Nd, Fe, and B to the valence-band structure of Nd{sub 2}Fe{sub 14}B compound is made more clear. The B 2p states and B 2s states are identified to be at ∼11.2 eV and ∼24.6 eV, respectively, which is reported for the first time. The contribution from Nd 4f states can be identified both in XPS core-level spectrum and XPS valence-band spectrum. Although Nd 4f states partially hybridize with Fe 3d states, Nd 4f states are mainly localized in Nd{sub 2}Fe{sub 14}B compound.

  19. CYP4F2 genetic variant alters required warfarin dose

    PubMed Central

    Caldwell, Michael D.; Awad, Tarif; Johnson, Julie A.; Gage, Brian F.; Falkowski, Mat; Gardina, Paul; Hubbard, Jason; Turpaz, Yaron; Langaee, Taimour Y.; Eby, Charles; King, Cristi R.; Brower, Amy; Schmelzer, John R.; Glurich, Ingrid; Vidaillet, Humberto J.; Yale, Steven H.; Qi Zhang, Kai; Berg, Richard L.

    2008-01-01

    Warfarin is an effective, commonly prescribed anticoagulant used to treat and prevent thrombotic events. Because of historically high rates of drug-associated adverse events, warfarin remains underprescribed. Further, interindividual variability in therapeutic dose mandates frequent monitoring until target anticoagulation is achieved. Genetic polymorphisms involved in warfarin metabolism and sensitivity have been implicated in variability of dose. Here, we describe a novel variant that influences warfarin requirements. To identify additional genetic variants that contribute to warfarin requirements, screening of DNA variants in additional genes that code for drug-metabolizing enzymes and drug transport proteins was undertaken using the Affymetrix drug-metabolizing enzymes and transporters panel. A DNA variant (rs2108622; V433M) in cytochrome P450 4F2 (CYP4F2) was associated with warfarin dose in 3 independent white cohorts of patients stabilized on warfarin representing diverse geographic regions in the United States and accounted for a difference in warfarin dose of approximately 1 mg/day between CC and TT subjects. Genetic variation of CYP4F2 was associated with a clinically relevant effect on warfarin requirement. PMID:18250228

  20. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Coverage under section 4(f)(4). 55.5... section 4(f)(4). (a) Coverage formula. Section 4(f)(4) applies to any State or political subdivision in... under section 4(f)(4). 1 1 Coverage is based on sections 4(b) (third sentence), 4(c), and......

  1. Lattice dynamics of neodymium: Influence of 4 f electron correlations

    NASA Astrophysics Data System (ADS)

    Waller, O.; Piekarz, P.; Bosak, A.; Jochym, P. T.; Ibrahimkutty, S.; Seiler, A.; Krisch, M.; Baumbach, T.; Parlinski, K.; Stankov, S.

    2016-07-01

    Incorporation of strong electron correlations into the density functional theory (DFT) for the electronic structure calculations of light lanthanides leads to a modification of interatomic forces and consequently the lattice dynamics. Using first-principles theory we demonstrate the substantial influence of the 4 f electron correlations on the phonon dispersion relations of Nd. The calculations are verified by an inelastic x-ray scattering experiment performed on a single-crystalline Nd(0001) film. We show that very good agreement between the calculated and measured data is achieved when electron-electron interactions are treated by the DFT +U approach.

  2. Toward Molecular 4f Single-Ion Magnet Qubits.

    PubMed

    Pedersen, Kasper S; Ariciu, Ana-Maria; McAdams, Simon; Weihe, Høgni; Bendix, Jesper; Tuna, Floriana; Piligkos, Stergios

    2016-05-11

    Quantum coherence is detected in the 4f single-ion magnet (SIM) Yb(trensal), by isotope selective pulsed EPR spectroscopy on an oriented single crystal. At X-band, the spin-lattice relaxation (T1) and phase memory (Tm) times are found to be independent of the nuclei bearing, or not, a nuclear spin. The observation of Rabi oscillations of the spin echo demonstrates the possibility to coherently manipulate the system for more than 70 rotations. This renders Yb(trensal), a sublimable and chemically modifiable SIM, an excellent candidate for quantum information processing. PMID:27105449

  3. ee4fγ—A program for e+e-→4f,4f γ with nonzero fermion masses

    NASA Astrophysics Data System (ADS)

    Kołodziej, Karol; Jegerlehner, Fred

    2004-05-01

    A computer program ee4fγ for calculating cross-sections of any four fermion final state of e+e--annihilation at high energy and the corresponding bremsstrahlung reaction that is possible in the framework of the Standard Model is presented. As the fermion masses are arbitrary, the cross-sections for channels that do not contain e+ and/or e- in the final state can be computed without any collinear cut, the on-shell top quark production can be studied and the Higgs boson exchange can be incorporated in a consistent way. The program can be used as a Monte Carlo generator of unweighted events as well. Program summaryTitle of program:ee4fγ Version: 1.0 (February 2004) Catalogue identifier: ADTQ Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADTQ Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: none Computers: all Operating systems: Unix/Linux Programming language used:FORTRAN 90 CPC Program Library subprograms used:RANLUX, ACPR RANLUX 79 (1994) 111—a random number generator Memory required to execute with typical data: 4.0 Mb No. of bits in a word: 32 No. of bytes in distributed program, including test data, etc.: 364 490 No. of lines in distributed program, including test data, etc.: 45 278 Distribution format: tar gzip file Nature of physical problem: Description of all e+e-→4 fermions and corresponding bremsstrahlung reactions that are possible in the Standard Model (SM) to lowest order and with nonzero fermion masses at center of mass energies typical for next generation linear colliders. Such reactions are relevant, typically, for W-pair or intermediate mass Higgs boson production and decay. Method of solution: Matrix elements are calculated with the helicity amplitude method. The phase space integration is performed numerically utilizing a multi-channel Monte Carlo method. Restrictions on complexity of the problem: No higher order effects are taken into account, except for assuming the fine

  4. Weak anisotropic x-ray magnetic linear dichroism at the Eu M4,5 edges of ferromagnetic EuO(001): evidence for 4f-state contributions.

    PubMed

    van der Laan, Gerrit; Arenholz, Elke; Schmehl, Andreas; Schlom, Darrell G

    2008-02-15

    We have observed a weak anisotropic x-ray magnetic linear dichroism (AXMLD) at the Eu M4,5 edges of ferromagnetic EuO(001), which indicates that the 4f states are not rotationally invariant. A quantitative agreement of the AXMLD is obtained with multiplet calculations where the 4f state is split by an effective cubic crystalline electrostatic field. The results indicate that the standard model of rare earths, where 4f electrons are treated as core states, is not correct and that the 4f orbitals contribute weakly to the magnetic anisotropy. PMID:18352515

  5. Surface analysis of zeolites: An XPS, variable kinetic energy XPS, and low energy ion scattering study

    NASA Astrophysics Data System (ADS)

    Bare, Simon R.; Knop-Gericke, Axel; Teschner, Detre; Hävacker, Michael; Blume, Raoul; Rocha, Tulio; Schlögl, Robert; Chan, Ally S. Y.; Blackwell, N.; Charochak, M. E.; ter Veen, Rik; Brongersma, Hidde H.

    2016-06-01

    The surface Si/Al ratio in a series of zeolite Y samples has been obtained using laboratory XPS, synchrotron (variable kinetic energy) XPS, and low energy ion scattering (LEIS) spectroscopy. The non-destructive depth profile obtained using variable kinetic energy XPS is compared to that from the destructive argon ion bombardment depth profile from the lab XPS instrument. All of the data indicate that the near surface region of both the ammonium form and steamed Y zeolites is strongly enriched in aluminum. It is shown that when the inelastic mean free path of the photoelectrons is taken into account the laboratory XPS of aluminosilicates zeolites does not provide a true measurement of the surface stoichiometry, while variable kinetic energy XPS results in a more surface sensitive measurement. A comprehensive Si/Al concentration profile as a function of depth is developed by combining the data from the three surface characterization techniques. The LEIS spectroscopy reveals that the topmost atomic layer is further enriched in Al compared to subsequent layers.

  6. Band structures of 4f and 5f materials studied by angle-resolved photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Fujimori, Shin-ichi

    2016-04-01

    Recent remarkable progress in angle-resolved photoelectron spectroscopy (ARPES) has enabled the direct observation of the band structures of 4f and 5f materials. In particular, ARPES with various light sources such as lasers (hν ∼ 7~\\text{eV} ) or high-energy synchrotron radiations (hν ≳ 400~\\text{eV} ) has shed light on the bulk band structures of strongly correlated materials with energy scales of a few millielectronvolts to several electronvolts. The purpose of this paper is to summarize the behaviors of 4f and 5f band structures of various rare-earth and actinide materials observed by modern ARPES techniques, and understand how they can be described using various theoretical frameworks. For 4f-electron materials, ARPES studies of \\text{Ce}M\\text{I}{{\\text{n}}5} (M=\\text{Rh} , \\text{Ir} , and \\text{Co} ) and \\text{YbR}{{\\text{h}}2}\\text{S}{{\\text{i}}2} with various incident photon energies are summarized. We demonstrate that their 4f electronic structures are essentially described within the framework of the periodic Anderson model, and that the band-structure calculation based on the local density approximation cannot explain their low-energy electronic structures. Meanwhile, electronic structures of 5f materials exhibit wide varieties ranging from itinerant to localized states. For itinerant \\text{U}~5f compounds such as \\text{UFeG}{{\\text{a}}5} , their electronic structures can be well-described by the band-structure calculation assuming that all \\text{U}~5f electrons are itinerant. In contrast, the band structures of localized \\text{U}~5f compounds such as \\text{UP}{{\\text{d}}3} and \\text{U}{{\\text{O}}2} are essentially explained by the localized model that treats \\text{U}~5f electrons as localized core states. In regards to heavy fermion \\text{U} -based compounds such as the hidden-order compound \\text{UR}{{\\text{u}}2}\\text{S}{{\\text{i}}2} , their electronic structures exhibit complex behaviors. Their overall band structures

  7. Encoding degree testing in a 4f architecture

    NASA Astrophysics Data System (ADS)

    Amaya, Dafne; Tebaldi, Myrian; Torroba, Roberto; Bolognini, Néstor

    2011-08-01

    The distribution of the encrypted information at the output of an encoding system is of major concern. When the encrypted information is conveyed to the final user, the finite size of the recording medium affects the quality of the encoded information. In this case, we face possible information degradation when recovering. In the present contribution we focus our attention on the finite size of the recorder medium in an actual experimental situation. In order to improve the quality of the decrypted data, we study the role that both the scattering element size of the masks and the input object size play in the encrypting system. Therefore, we analyze the optimal spatial distribution of the encoded information at the output of a 4f encrypting system. We present examples that support our proposal.

  8. Nitrogen-doped TiO2 modified with NH4F for efficient photocatalytic degradation of formaldehyde under blue light-emitting diodes.

    PubMed

    Li, Yuexiang; Jiang, Yuan; Peng, Shaoqin; Jiang, Fengyi

    2010-10-15

    A nitrogen-doped TiO(2) (N-TiO(2)) photocatalyst was prepared by calcination of the hydrolysis precipitate of Ti(SO(4))(2) with aqueous ammonia. The prepared N-TiO(2) was treated with NH(4)F (F-N-TiO(2)) by an impregnation-calcination method. The photocatalyst (F-N-TiO(2)) was characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), UV-vis diffusive reflectance spectroscopy (DRS), BET and X-ray photoelectron spectroscopy (XPS). With blue light-emitting diode (LED) as the light source, its photocatalytic activity for the degradation of formaldehyde was investigated. NH(4)F treatment enhances markedly photocatalytic activity of N-TiO(2). The treatment increases the visible absorption of N-TiO(2), decreases its specific surface area and influences the concentration of oxygen vacancies in N-TiO(2). Photocatalytic activity of F-N-TiO(2) depends on the visible absorption, the specific surface area, and the concentration of oxygen vacancies. The preparation conditions, such as the calcination temperature and the initial molar ratio of NH(4)F to N-TiO(2), have a significant influence on the photocatalytic activity. The doping mechanism of NH(4)F was investigated. PMID:20580490

  9. XPS Study of Ion Irradiated and Unirradiated UO2 Thin Films.

    PubMed

    Teterin, Yury A; Popel, Aleksej J; Maslakov, Konstantin I; Teterin, Anton Yu; Ivanov, Kirill E; Kalmykov, Stepan N; Springell, Ross; Scott, Thomas B; Farnan, Ian

    2016-08-15

    XPS determination of the oxygen coefficient kO = 2 + x and ionic (U(4+), U(5+), and U(6+)) composition of oxides UO2+x formed on the surfaces of differently oriented (hkl) planes of thin UO2 films on LSAT (Al10La3O51Sr14Ta7) and YSZ (yttria-stabilized zirconia) substrates was performed. The U 4f and O 1s core-electron peak intensities as well as the U 5f relative intensity before and after the (129)Xe(23+) and (238)U(31+) irradiations were employed. It was found that the presence of uranium dioxide film in air results in formation of oxide UO2+x on the surface with mean oxygen coefficients kO in the range 2.07-2.11 on LSAT and 2.17-2.23 on YSZ substrates. These oxygen coefficients depend on the substrate and weakly on the crystallographic orientation. On the basis of the spectral parameters it was established that uranium dioxide films AP2,3 on the LSAT substrates have the smallest kO values, and from the XRD and EBSD results it follows that these samples have a regular monocrystalline structure. The XRD and EBSD results indicate that samples AP5-7 on the YSZ substrates have monocrystalline structure; however, they have the highest kO values. The observed difference in the kO values was probably caused by the different nature of the substrates: the YSZ substrates provide 6.4% compressive strain, whereas (001) LSAT substrates result only in 0.03% tensile strain in the UO2 films. (129)Xe(23+) irradiation (92 MeV, 4.8 × 10(15) ions/cm(2)) of uranium dioxide films on the LSAT substrates was shown to destroy both long-range ordering and uranium close environment, which results in an increase of uranium oxidation state and regrouping of oxygen ions in uranium close environment. (238)U(31+) (110 MeV, 5 × 10(10), 5 × 10(11), 5 × 10(12) ions/cm(2)) irradiations of uranium dioxide films on the YSZ substrates were shown to form the lattice damage only with partial destruction of the long-range ordering. PMID:27490370

  10. EXPRESSION OF CYP4F2 IN HUMAN LIVER AND KIDNEY: ASSESSMENT USING TARGETED PEPTIDE ANTIBODIES

    PubMed Central

    Hirani, Vandana; Yarovoy, Anton; Kozeska, Anita; Magnusson, Ronald P.; Lasker, Jerome M.

    2008-01-01

    P450 enzymes comprising the human CYP4F gene subfamily are catalysts of eicosanoid (e.g., 20-HETE and leukotriene B4) formation and degradation, although the role that individual CYP4F proteins play in these metabolic processes is not well defined. Thus, we developed antibodies to assess the tissue-specific expression and function of CYP4F2, one of four CYP4F P450s found in human liver and kidney. Peptide antibodies elicited in rabbits to CYP4F2 amino acid residues 61–74 (WGHQGMVNPTEEG) and 65–77 (GMVNPTEEGMRVL) recognized on immunoblots only CYP4F2 and not CYP4F3b, CYP4F11 or CYP4F12. Immunoquantitation with anti-CYP4F2 peptide IgG showed highly-variable CYP4F2 expression in liver (16.4 ± 18.6 pmol/mg microsomal protein; n = 29) and kidney cortex (3.9 ± 3.8 pmol/mg; n = 10), with two subjects lacking the hepatic or renal enzyme entirely. CYP4F2 content in liver microsomes was significantly correlated (r ≥ 0.63; p < 0.05) with leukotriene B4 and arachidonate ω-hydroxylase activities, which are both CYP4F2-catalyzed. Our study provides the first example of a peptide antibody that recognizes a single CYP4F P450 expressed in human liver and kidney, namely CYP4F2. Immunoquantitation and correlation analyses performed with this antibody suggest that CYP4F2 functions as a predominant LTB4 and arachidonate ω-hydroxylase in human liver. PMID:18662666

  11. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Relationship between section 4(f)(4) and....8 Relationship between section 4(f)(4) and section 203(c). (a) The statutory requirements of section 4(f)(4) and section 203(c) regarding minority language material and assistance are...

  12. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Relationship between section 4(f)(4) and....8 Relationship between section 4(f)(4) and section 203(c). (a) The statutory requirements of section 4(f)(4) and section 203(c) regarding minority language material and assistance are...

  13. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Relationship between section 4(f)(4) and....8 Relationship between section 4(f)(4) and section 203(c). (a) The statutory requirements of section 4(f)(4) and section 203(c) regarding minority language material and assistance are...

  14. The interpretation of XPS spectra: Insights into materials properties

    NASA Astrophysics Data System (ADS)

    Bagus, Paul S.; Ilton, Eugene S.; Nelin, Connie J.

    2013-06-01

    "passive" electrons are fixed or frozen as they are for the initial state before ionization. FWHM: full width at half maximum. HF: Hartree-Fock. This is used to describe the wavefunctions and other properties that result from Hartree-Fock calculations. Irel: relative intensity. In this context, the intensities of the different XPS peaks arising from the ionization of the same primary electron. KT: Koopmans' theorem. Used to describe energies obtained by freezing orbitals of the "passive" electrons when an electron is ionized; closely related to FO properties. PES: photoemission spectroscopy SA: sudden approximation. An approximation for the calculation of the relative intensity of the XPS ionization into a particular ionic state; the approximation is exact in the limit of ionization by very high energy photons. SCF: self-consistent field. SCLS: surface core level shift. This is used to describe the BE shift between photoelectrons arising from the surface and from the bulk of a crystal. XPS: X-ray photoelectron spectroscopy.

  15. Rare earth 4f hybridization with the GaN valence band

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Mei, Wai-Ning; McHale, S. R.; McClory, J. W.; Petrosky, J. C.; Wu, J.; Palai, R.; Losovyj, Y. B.; Dowben, P. A.

    2012-11-01

    The placement of the Gd, Er and Yb 4f states within the GaN valence band has been explored by both experiment and theory. The 4d-4f photoemission resonances for various rare-earth(RE)-doped GaN thin films (RE = Gd, Er, Yb) provide an accurate depiction of the occupied 4f state placement within the GaN. The resonant photoemission show that the major Er and Gd RE 4f weight is at about 5-6 eV below the valence band maximum, similar to the 4f weights in the valence band of many other RE-doped semiconductors. For Yb, there is a very little resonant enhancement of the valence band of Yb-doped GaN, consistent with a large 4f14-δ occupancy. The placement of the RE 4f levels is in qualitative agreement with theoretical expectations.

  16. The rare earth 4 f hybridization with the GaN valence band

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Mei, Wai-Ning; McHale, Steve; McClory, John; Petrosky, James; Wu, J.; Palai, Ratnakar; Losovyj, Yaroslav; Dowben, Peter

    2013-03-01

    The placement of the Gd, Er, and Yb 4f states within the GaN valence band has been explored by both experiment and theory. The 4 d - 4 f photoemission resonances for various rare earth doped GaN thin films (RE = Gd, Er, Yb) provide an accurate depiction of the occupied 4 f state placement within the GaN. The resonant photoemission show that the major Er and Gd rare earth 4 f weight is at about 5-6 eV below the valence band maximum, similar to the 4 f weights in the valence band of many other rare earth doped semiconductors. For Yb, there is very little resonant enhancement of the valence band of Yb doped GaN, consistent with a largely 4f 14 - δ occupancy. The placement of the rare earth 4 f levels is in qualitative agreement with theoretical expectations.

  17. Au 4f spin-orbit coupling effects in supported gold nanoparticles.

    PubMed

    Chenakin, Sergey P; Kruse, Norbert

    2016-08-17

    Using X-ray photoelectron spectroscopy we examine the Au 4f spin-orbit components in Au 4f spectra of nanosized Au particles on a TiO2 support. In general, the peak ratios of the Au 4f7/2 and 4f5/2 excitations are found to deviate from the statistical ratio of 4 : 3 and their linewidths (FWHM) are not equal. We reveal that both the FWHM and the Au 4f7/2-to-4f5/2 peak ratios increase appreciably as the Au atomic concentration on the surface of the TiO2 support and the size of Au nanoparticles decrease. On the contrary, the Au 4f spin-orbit splitting remains essentially unchanged. Our findings are discussed in terms of alterations in the electronic band structure. PMID:27480507

  18. XPS characterization of naturally aged wood

    NASA Astrophysics Data System (ADS)

    Popescu, Carmen-Mihaela; Tibirna, Carmen-Mihaela; Vasile, Cornelia

    2009-12-01

    Wood deterioration over time (by a simultaneously biological, chemical or physical attack) is an inevitable continuous process in the environment. This process destroys all heritage resulting in a loss of valuable old wooden structures and their properties. What type of deterioration occurs and how these processes impact the wood are important questions that need consideration if old wooden structures are to be studied and properly preserved. X-ray photoelectron spectroscopy (XPS) was employed to analyze the undegraded (sound wood of ˜6 years) and degraded lime wood (˜150 years, ˜180 years, ˜250 years) from painting supports, differing in terms of the provenance, conservation status and environmental conditions of storage. Elaborated XPS analysis (comparison of C and O individual spectra, decomposition for each atomic component, calculation of O/C ratio) provided a view of the composition of the sample surfaces analyzed. On the basis of these results, it was confirmed that significant changes occurred in the first period of ageing, the ˜150 years lime wood sample having the highest percent of the carbon atoms and the lowest percentage of oxygen atoms and, respectively O/C ratio. According to our previous studies (X-ray diffraction, FTIR spectroscopy, analytical pyrolysis combined with gas chromatography/mass spectrometry and ESR-spectroscopy results), these features could be attributed to the fact that hemicelluloses and amorphous cellulose are degraded in time, whereas the crystalline fraction of cellulose decreases more slowly than the amorphous one. Consequently, the observation may be made that lignin is not so easily degraded under the environmental conditions where paintings are frequently exposed.

  19. Laser Spectroscopy of Dysprosium Monofluoride: Ligand Field Assignments of States Belonging to the 4 f96 s2, 4 f106 s, and 4 f96 s6 pSuperconfigurations

    NASA Astrophysics Data System (ADS)

    McCarthy, Michael C.; Bloch, Jonathan C.; Field, Robert W.; Kaledin, Leonid A.

    1996-10-01

    The techniques of selectively detected fluorescence excitation and dispersed fluorescence spectroscopy have been used to characterize two [19.3]8.5 and [20.3]8.5 electronic states of DyF in the region of ∼2.5 eV and five electronic states withT0< 6500 cm-1. Superconfigurational assignments of the observed low-lying states have been made on the basis of vibrational frequencies. TheX(1)7.5 ground state, with ΔG1/2≈ 605 cm-1, is assigned to the Dy+4f96s2superconfiguration, whereas four states, (1)8.5, (2)7.5, (3)7.5, and (4)7.5, with ΔG1/2≈ 508-544 cm-1are assigned to the Dy+4f106ssuperconfiguration. The lowest 4f106s(Ω = 8.5) state is found to lie 2431 cm-1above the 4f96s2X(1)7.5 ground state, thus establishing the linkage between the 4f96s2and 4f106ssuperconfigurations. The upper states in the region of ∼2.5 eV ([19.3]8.5 and [20.3]8.5) are assigned to the Dy+4f96s6psuperconfiguration on the basis of computed ligand field monopoleB00(nl,nl) orbital destabilization energies. The observed electronic states are discussed in relation to predictions of the ligand field theoretical model.

  20. Evolution from antiferromagnetic to paramagnetic Kondo insulator with increasing hybridization; XPS studies

    NASA Astrophysics Data System (ADS)

    Ślebarski, A.; Goraus, J.

    2012-12-01

    We present the Ce 3d x-ray photoemission (XPS) spectra for CeM2Al10 (M=Ru, Os, Fe) from which we determined the on-site hybridization between the f and conduction electron states, Δcf, and the 4f-level occupancy, nf. Those parameters have been obtained using the Gunnarsson-Schönhammer approach. We found Δcf stronger for the Kondo insulator CeFe2Al10 than for the remaining compounds with Ru and Os. We discuss the type of behaviour of CeM2Al10 on the base of the earlier theoretical phase diagram obtained within the Anderson-lattice model.

  1. Spectroscopy and calculations for 4f(N) → 4f(N-1)5d transitions of lanthanide ions in K3YF6.

    PubMed

    Ma, Chong-Geng; Brik, Mikhail G; Ryba-Romanowski, Witold; Swart, Hendrik C; Gusowski, Marek A

    2012-09-13

    In the present work, we report on the combined experimental and theoretical studies of the 4f-5d spectra of Ce(3+), Pr(3+), Nd(3+), Eu(3+), Gd(3+), Tb(3+), Dy(3+), and Er(3+) ions in a newly synthesized K3YF6 matrix. The low temperature experimental 4f-5d excitation spectra have been analyzed and compared with the results of the energy-level and intensity calculations. For this theoretical analysis, the extended phenomenological crystal-field model for the 4f(N-1)5d configuration (i.e., the extended f-shell programs, developed by Prof. M. F. Reid) and exchange charge model (developed by Prof. B. Z. Malkin) have been used together to estimate the crystal field parameters and implement the spectral simulations. On the basis of the results of the performed theoretical analysis, we suggest the most probable positions occupied by optically active ions. Although the spectra of only eight lanthanide ions have been studied, the Hamiltonian parameters of the 4f(N-1)5d configuration have been evaluated for the whole lanthanide series and reported here for the first time, to give a complete and unified description of the spectroscopic properties of the trivalent rare earth ions in the chosen host. In addition to the studies of the 4f-5d transitions, various possible competitive excitation channels overlapping with 4f-5d ones have also been discussed, where a theoretical scheme giving rudiments to understand 4f-6s spectra are proposed for the first time. An excellent agreement between the calculated and measured excitation spectra shapes confirms validity of the performed analysis. The obtained parameters of the crystal field Hamiltonians for different ions and various electron configurations can be used in a straightforward way to generate the energy level positions and calculate the particular transition intensities for any rare earth ion in any particular spectral region. With the aid of the obtained parameters, the positions of the lowest energy levels of the 4f(N), 4f(N-1

  2. Investigation of x-ray photoelectron spectroscopic (XPS), cyclic voltammetric analyses of WO3 films and their electrochromic response in FTO/WO3/electrolyte/FTO cells

    NASA Astrophysics Data System (ADS)

    Sivakumar, R.; Gopalakrishnan, R.; Jayachandran, M.; Sanjeeviraja, C.

    2006-06-01

    Electrochromic thin films of tungsten oxide (WO3) were prepared on transparent conducting oxide substrates, i.e., fluorine doped tin oxide coated (FTO or SnO2:F) glass and microscopic glass substrates by the electron beam evaporation technique using pure WO3 (99.99%) pellets at various substrate temperatures (i.e., Tsub = room temperature (RT, 30 °C), 100 °C and 200 °C). The films were prepared under vacuum of the order of 1 × 10-5 mbar. The room temperature prepared films were further post-heat-treated (Tanne) at 200 and 300 °C for about 1 h in the vacuum environment. The prepared films are in monoclinic phase. The chemical composition has been characterized by using the XPS technique. The W 4f and O 1s core levels of WO3 films have been studied on the samples. The obtained core level binding energies revealed the WO3 films contained six-valent tungsten (W6+). The electrochemical nature of the films was studied by a three-electrode electrochemical cell in the configuration of FTO/WO3/H2SO4/Pt, SCE, using the cyclic voltammetry (CV) technique. Electrochromic devices (ECDs) of the general type FTO/WO3/electrolyte/FTO were studied. The films produced at higher substrate temperature show smaller modulation of the visible spectrum, compared with the films produced at lower temperatures. The significant chemical bonding nature associated with the coloring/bleaching process which follows the H+ ion incorporation in the film is studied by FTIR analysis. The W-O-W framework peak was observed at 563 cm-1 and confirms the stability of the films in the electrochemical analysis. The results obtained from cyclic voltammetry technique and ECD cell characterization are used to emphasize the suitability for some applications of the solar control systems.

  3. Ligand field density functional theory calculation of the 4f2→ 4f15d1 transitions in the quantum cutter Cs2KYF6:Pr3+.

    PubMed

    Ramanantoanina, Harry; Urland, Werner; Cimpoesu, Fanica; Daul, Claude

    2013-09-01

    Herein we present a Ligand Field Density Functional Theory (LFDFT) based methodology for the analysis of the 4f(n)→ 4f(n-1)5d(1) transitions in rare earth compounds and apply it for the characterization of the 4f(2)→ 4f(1)5d(1) transitions in the quantum cutter Cs2KYF6:Pr(3+) with the elpasolite structure type. The methodological advances are relevant for the analysis and prospection of materials acting as phosphors in light-emitting diodes. The positions of the zero-phonon energy corresponding to the states of the electron configurations 4f(2) and 4f(1)5d(1) are calculated, where the praseodymium ion may occupy either the Cs(+)-, K(+)- or the Y(3+)-site, and are compared with available experimental data. The theoretical results show that the occupation of the three undistorted sites allows a quantum-cutting process. However size effects due to the difference between the ionic radii of Pr(3+) and K(+) as well as Cs(+) lead to the distortion of the K(+)- and the Cs(+)-site, which finally exclude these sites for quantum-cutting. A detailed discussion about the origin of this distortion is also described. PMID:23846586

  4. Polytypism in wagnerite, Mg2PO4(F,OH)

    NASA Astrophysics Data System (ADS)

    Chopin, C.; Armbruster, T.; Leyx, C.

    2003-04-01

    The Mg, Fe and Mn phosphates with formula Me2+_2PO_4(F,OH) belong to two groups which share the same fundamental monoclinic structure type, but in one of which the b parameter is doubled. Specifically, magniotriplite (Mg), zwieselite (Fe) and triplite (Mn) are F-dominant and have space group I2/a, with Z = 8, b_0 ≈ 6.5 Å, whereas wagnerite (Mg, F dominant), wolfeite (Fe, OH dominant) and triploidite (Mn, OH dominant) have space group P2_1/a, Z = 16 and b = 2 b_0 ≈ 13 Å. In I2/a magniotriplite, eight F atoms are distributed over two eightfold equipoints with 50% occupancy. Periodic ordering of the F atoms into each of these equipoint positions (say A and B), each alternately void and fully occupied along b, leads to a new, double cell with space group P2_1/a and a 2b_0 parameter, i.e. the wagnerite cell, in which the succession of the occupied F positions along b is ABAB (Tadini 1981). Ren et al. (2002) reported from granulite-facies rocks of East Antarctica a wagnerite "polymorph" structurally very close to wagnerite, but with space group Ia, b = 5b_0 ≈ 32 Å and Z = 40. We studied wagnerite crystals from granulite-facies rocks of central Australia (Vry and Cartwright 1994). CCD area-detector imaging revealed either 7b_0 ≈ 45 Å or 9b_0 ≈ 57 Å superstructures (Z = 56 and 72, respectively). The structure of the 9b_0 phase was refined in space group Ia to R = 6% from 11903 unique reflections. We show that wagnerite and the 5b_0, 7b_0 and 9b_0 phases share the same topological arrangement of cations and oxygen atoms, differ only by the periodic faulting of the A-B succession of the F atoms along b, and are all members of a polytypic series based on the magniotriplite cell (b_0). The relevant polytypes and F ordering schemes are wagnerite-a2bc (AB), wagnerite-a5bc (ABAAB), wagnerite-a7bc (ABAABAB) and wagnerite-a9bc (ABAABABAB). Reinvestigation of OH-rich wagnerite from Miregn (Central Alps) and of OH-rich to OH-dominant wagnerite from Dora-Maira (W. Alps

  5. The screening of 4f moments and delocalization in the compressed light rare earths

    SciTech Connect

    McMahan, A K; Scalettar, R T; Jarrell, M

    2009-08-19

    Spin and charge susceptibilities and the 4f{sup n}, 4f{sup n{+-}1} configuration weights are calculated for compressed Ce (n=1), Pr (n=2), and Nd (n=3) metals using dynamical mean field theory combined with the local-density approximation. At ambient and larger volumes these trivalent rare earths are pinned at sharp 4f{sup n} configurations, their 4f moments assume atomic-limiting values, are unscreened, and the 4f charge fluctuations are small indicating little f state density near the Fermi level. Under compresssion there is dramatic screening of the moments and an associated increase in both the 4f charge fluctuations and static charge susceptibility. These changes are coincident with growing weights of the 4f{sup n-1} configurations, which it is argued are better measures of delocalization than the 4f{sup n+1} weights which are compromised by an increase in the number of 4f electrons caused by rising 6s, 6p bands. This process is continuous and prolonged as a function of volume, with strikingly similarity among the three rare earths, aside from the effects moderating and shifting to smaller volumes for the heavier members. The observed {alpha}-{gamma} collapse in Ce occurs over the large-volume half of this evolution, the Pr analog at smaller volumes, and Nd has no collapse.

  6. 5 d-4 f luminescence of Er 3+ in YAG:Er 3+

    NASA Astrophysics Data System (ADS)

    Aleksanyan, Eduard; Harutunyan, Vachagan; Kostanyan, Radik; Feldbach, Eduard; Kirm, Marco; Liblik, Peeter; Makhov, Vladimir N.; Vielhauer, Sebastian

    2009-04-01

    Interconfigurational 4 f105 d ↔ 4 f11 transitions of the Er 3+ ion in the YAG host were studied under both VUV photon (synchrotron radiation) and electron beam excitation. It was found that the lowest low-spin 5 d level of the Er 3+ ion has a rather large energy gap to the next lower 4 f2D(2) 5/2 crystal-field level, which results in a relatively low rate of nonradiative transitions from this 5 d level leading to the appearance of weak spin-allowed 5 d-4 f luminescence at low temperature. The lowest high-spin 5 d level, from which spin-forbidden 5 d-4 f radiative transitions could occur potentially, is situated only at ˜500 cm -1 above the 4D1/2 level. Such close location allows fast depopulation of the 5 d level resulting in the absence of spin-forbidden 5 d-4 f luminescence and appearance of 4D1/2 4 f-4 f luminescence.

  7. Bioenergetic programming of macrophages by the apolipoprotein A-I mimetic peptide 4F.

    PubMed

    Datta, Geeta; Kramer, Philip A; Johnson, Michelle S; Sawada, Hirotaka; Smythies, Lesley E; Crossman, David K; Chacko, Balu; Ballinger, Scott W; Westbrook, David G; Mayakonda, Palgunachari; Anantharamaiah, G M; Darley-Usmar, Victor M; White, C Roger

    2015-05-01

    The apoA-I (apolipoprotein A-I) mimetic peptide 4F favours the differentiation of human monocytes to an alternatively activated M2 phenotype. The goal of the present study was to test whether the 4F-mediated differentiation of MDMs (monocyte-derived macrophages) requires the induction of an oxidative metabolic programme. 4F treatment induced several genes in MDMs that play an important role in lipid metabolism, including PPARγ (peroxisome-proliferator-activated receptor γ) and CD36. Addition of 4F was associated with a significant increase in FA (fatty acid) uptake and oxidation compared with vehicle treatment. Mitochondrial respiration was assessed by measurement of the OCR (oxygen-consumption rate). 4F increased basal and ATP-linked OCR as well as maximal uncoupled mitochondrial respiration. These changes were associated with a significant increase in ΔΨm (mitochondrial membrane potential). The increase in metabolic activity in 4F-treated MDMs was attenuated by etomoxir, an inhibitor of mitochondrial FA uptake. Finally, addition of the PPARγ antagonist T0070907 to 4F-treated MDMs reduced the expression of CD163 and CD36, cell-surface markers for M2 macrophages, and reduced basal and ATP-linked OCR. These results support our hypothesis that the 4F-mediated differentiation of MDMs to an anti-inflammatory phenotype is due, in part, to an increase in FA uptake and mitochondrial oxidative metabolism. PMID:25742174

  8. XPS study of thallium oxidation states in precursor TlBaCaCuO HTSC thin films

    NASA Astrophysics Data System (ADS)

    Young, K. H.; Smith, E. J.; Eddy, M. M.; James, T. W.

    1991-10-01

    The Tl oxidation state in the precursor of Tl 2Ba 2CaCu 2O 8 superconducting films plays an important role in the post-deposition process and has been carefully examined by X-ray photoelectron spectroscopy (XPS). The Tl4f 5/2 and Tl4f 5/2 peaks in the XPS spectra have been deconvoluted into several peaks corresponding to different oxidation states. Under normal deposition conditions for laser ablation, it is found that mixtures of Tl-I(+ 1 oxidation state) and Tl-III (+ 3) are present with various percentages. The study of time evolution and depth profile data suggests that the surface oxidation state is a function of time and 200 Å of film should be removed before collecting data. The Tl-oxidation state depends strongly on the oxygen background pressure during deposition and the optimal pressure is found to be about 180 mTorr. Negatively charged Tl (presumably due to alloying with other metal constituents) is found when deposited with no background oxygen pressure.

  9. 4F decreases IRF5 expression and activation in hearts of tight skin mice.

    PubMed

    Xu, Hao; Krolikowski, John G; Jones, Deron W; Ge, Zhi-Dong; Pagel, Paul S; Pritchard, Kirkwood A; Weihrauch, Dorothée

    2012-01-01

    The apoAI mimetic 4F was designed to inhibit atherosclerosis by improving HDL. We reported that treating tight skin (Tsk(-/+)) mice, a model of systemic sclerosis (SSc), with 4F decreases inflammation and restores angiogenic potential in Tsk(-/+) hearts. Interferon regulating factor 5 (IRF5) is important in autoimmunity and apoptosis in immune cells. However, no studies were performed investigating IRF5 in myocardium. We hypothesize that 4F differentially modulates IRF5 expression and activation in Tsk(-/+) hearts. Posterior wall thickness was significantly increased in Tsk(-/+) compared to C57Bl/6J (control) and Tsk(-/+) mice with 4F treatment assessed by echoradiography highlighting reduction of fibrosis in 4F treated Tsk(-/+) mice. IRF5 in heart lysates from control and Tsk/+ with and without 4F treatment (sc, 1 mg/kg/d, 6-8 weeks) was determined. Phosphoserine, ubiquitin, ubiquitin K(63) on IRF5 were determined on immunoprecipitates of IRF5. Immunofluorescence and TUNEL assays in heart sections were used to determine positive nuclei for IRF5 and apoptosis, respectively. Fluorescence-labeled streptavidin (SA) was used to determine endothelial cell uptake of biotinylated 4F. SA-agarose pulldown and immunoblotting for IRF5 were used to determine 4F binding IRF5 in endothelial cell cytosolic fractions and to confirm biolayer interferometry studies. IRF5 levels in Tsk(-/+) hearts were similar to control. 4F treatments decrease IRF5 in Tsk(-/+) hearts and decrease phosphoserine and ubiquitin K(63) but increase total ubiquitin on IRF5 in Tsk(-/+) compared with levels on IRF5 in control hearts. 4F binds IRF5 by mechanisms favoring association over dissociation strong enough to pull down IRF5 from a mixture of endothelial cell cytosolic proteins. IRF5 positive nuclei and apoptotic cells in Tsk(-/+) hearts were increased compared with controls. 4F treatments decreased both measurements in Tsk(-/+) hearts. IRF5 activation in Tsk(-/+) hearts is increased. 4F treatments

  10. Plant cap-binding complexes eukaryotic initiation factors eIF4F and eIFISO4F: molecular specificity of subunit binding.

    PubMed

    Mayberry, Laura K; Allen, M Leah; Nitka, Kelley R; Campbell, Lara; Murphy, Patricia A; Browning, Karen S

    2011-12-01

    The initiation of translation in eukaryotes requires a suite of eIFs that include the cap-binding complex, eIF4F. eIF4F is comprised of the subunits eIF4G and eIF4E and often the helicase, eIF4A. The eIF4G subunit serves as an assembly point for other initiation factors, whereas eIF4E binds to the 7-methyl guanosine cap of mRNA. Plants have an isozyme form of eIF4F (eIFiso4F) with comparable subunits, eIFiso4E and eIFiso4G. Plant eIF4A is very loosely associated with the plant cap-binding complexes. The specificity of interaction of the individual subunits of the two complexes was previously unknown. To address this issue, mixed complexes (eIF4E-eIFiso4G or eIFiso4E-eIF4G) were expressed and purified from Escherichia coli for biochemical analysis. The activity of the mixed complexes in in vitro translation assays correlated with the large subunit of the respective correct complex. These results suggest that the eIF4G or eIFiso4G subunits influence translational efficiency more than the cap-binding subunits. The translation assays also showed varying responses of the mRNA templates to eIF4F or eIFiso4F, suggesting that some level of mRNA discrimination is possible. The dissociation constants for the correct complexes have K(D) values in the subnanomolar range, whereas the mixed complexes were found to have K(D) values in the ∼10 nm range. Displacement assays showed that the correct binding partner readily displaces the incorrect binding partner in a manner consistent with the difference in K(D) values. These results show molecular specificity for the formation of plant eIF4F and eIFiso4F complexes and suggest a role in mRNA discrimination during initiation of translation. PMID:21965660

  11. NEXAFS and XPS of p-Aminobenzoic Acid Polymorphs: The Influence of Local Environment

    NASA Astrophysics Data System (ADS)

    Stevens, J. S.; Gainar, A.; Jaye, C.; Fischer, D. A.; Schroeder, S. L. M.

    2016-05-01

    Nitrogen K-edge XPS and NEXAFS of the two polymorphic forms of para- aminobenzoic acid (PABA) are significantly different reflecting variation in hydrogen bonding. Alteration in hydrogen bonding at the amino group leads to a shift to high energy for both the XPS N 1s core level and the 3π* NEXAFS resonance with β-PABA. Participation of the amine group in the aromatic system causes the 1π* resonance to be sensitive to the nature of the intermolecular bonding at the para-carboxylic acid group, and a shift to low energy for α- PABA is observed due to hydrogen-bonded carboxylic acid dimer formation. FEFF calculations also successfully reproduce both the energy and intensity variations observed for the σ* shape resonance associated with the C-N bond, with the majority of the decrease in energy observed for b-PABA arising from the longer C-N bond.

  12. X-Ray Photoelectron Spectroscopy (XPS) of Bacteriorhodopsin Analogues Synthesized from Fluorophenyl Retinals

    NASA Astrophysics Data System (ADS)

    Takahashi, Masae; Takahashi, Takashi; Tokunaga, Fumio; Murano, Kentaro; Tsujimoto, Kazuo; Sagawa, Takasi

    1984-04-01

    The two external point-charge (TEPC) model for bacteriorhodopsin (bR) has been examined by X-ray photoelectron spectroscopy (XPS) and CNDO/S molecular orbital calculations. A main concern was given to a point charge near the β-ionone ring. XPS measurements were carried out on fluorophenyl retinal (F-ret) and their derivatives (Schiff base, protonated Schiff base and bacteriorhodopsin analogues (F-bR)), paying close attention to the chemical shift of the F 1s core level. No meaningful differences were observed among these species although numerical calculations on an assumption of the TEPC model have predicted the chemical shift of about 3 eV between F-ret and F-bR. This fact has arisen a serious question to the validity of the TEPC model. The same conclusion has been reached by the present study of absorption maxima of F-ret and their derivatives.

  13. Apolipoprotein A-I mimetic peptide 4F blocks sphingomyelinase-induced LDL aggregation[S

    PubMed Central

    Nguyen, Su Duy; Javanainen, Matti; Rissanen, Sami; Zhao, Hongxia; Huusko, Jenni; Kivelä, Annukka M.; Ylä-Herttuala, Seppo; Navab, Mohamad; Fogelman, Alan M.; Vattulainen, Ilpo; Kovanen, Petri T.; Öörni, Katariina

    2015-01-01

    Lipolytic modification of LDL particles by SMase generates LDL aggregates with a strong affinity for human arterial proteoglycans and may so enhance LDL retention in the arterial wall. Here, we evaluated the effects of apoA-I mimetic peptide 4F on structural and functional properties of the SMase-modified LDL particles. LDL particles with and without 4F were incubated with SMase, after which their aggregation, structure, and proteoglycan binding were analyzed. At a molar ratio of L-4F to apoB-100 of 2.5 to 20:1, 4F dose-dependently inhibited SMase-induced LDL aggregation. At a molar ratio of 20:1, SMase-induced aggregation was fully blocked. Binding of 4F to LDL particles inhibited SMase-induced hydrolysis of LDL by 10% and prevented SMase-induced LDL aggregation. In addition, the binding of the SMase-modified LDL particles to human aortic proteoglycans was dose-dependently inhibited by pretreating LDL with 4F. The 4F stabilized apoB-100 conformation and inhibited SMase-induced conformational changes of apoB-100. Molecular dynamic simulations showed that upon binding to protein-free LDL surface, 4F locally alters membrane order and fluidity and induces structural changes to the lipid layer. Collectively, 4F stabilizes LDL particles by preventing the SMase-induced conformational changes in apoB-100 and so blocks SMase-induced LDL aggregation and the resulting increase in LDL retention. PMID:25861792

  14. Layers and tubes of fluorographene C4F: Stability, structural and electronic properties from DFTB calculations

    NASA Astrophysics Data System (ADS)

    Enyashin, A. N.; Ivanovskii, A. L.

    2013-06-01

    By means of the DFTB band structure calculations we have explored the layers' isomerism of fluorographene C4F. The relative stability, structural and electronic properties of the C4F layers and nanotubes have been revealed depending on the possible types of fluorine coverage: single-sided, double-sided or so-called non-uniform variants. Our main finding is that the aforementioned types of fluorine coverage are crucial for the morphology of these materials. At the non-uniform or single-sided coverage types the C4F structures aspire to the spontaneous folding in order to minimize their surface tension.

  15. Factor analysis and advanced inelastic background analysis in XPS: Unraveling time dependent contamination growth on multilayers and thin films

    NASA Astrophysics Data System (ADS)

    Gusenleitner, S.; Hauschild, D.; Graber, T.; Ehm, D.; Tougaard, S.; Reinert, F.

    2013-10-01

    In order to follow and understand time dependent contamination growth on multilayer mirrors for extreme ultraviolet (EUV) lithography applications, particular heterosystems were investigated with X-ray Photoemission Spectroscopy (XPS). Diverse capping layers can be used to terminate EUV multilayer mirrors to protect the underlying multilayer stack, e.g. Ru metal. In XPS problems were encountered when analyzing spectra as the core-level signals of Ru and C overlap. Further, Ru was not only present as pure metal, but also in its oxidized state. Disentangling the overlapping XPS spectra was achieved by application of factor analysis (FA) yielding not only the spectra of each component but also the according weights. Thus a model for the time dependent contamination growth was developed. This model was cross checked by advanced inelastic background analysis. Both methods displayed a way to unravel overlapping data sets and for deducing multilayer composition models.

  16. XPS surface study of nanocrystalline Ti Ru Fe materials

    NASA Astrophysics Data System (ADS)

    Suñol, J. J.; Bonneau, M. E.; Roué, L.; Guay, D.; Schulz, R.

    2000-02-01

    The surface properties of Ti:Ru:Fe (2- x:1+ x/2:1+ x/2) (with x=0, 0.25, 0.5, 0.75, and 1) and Ti:Ru:Fe:O (2:1:1: w) (with w=0.0, 0.5, 1.0, 1.5, and 2.0) have been determined by X-ray photoelectron spectroscopy (XPS) in both their as-milled state and after being in contact with a chlorate oxidizing solution. The O surface concentrations of both sets of samples are almost identical, indicating that the O-free samples readily react with air. All samples in their as-milled state have an elemental Ti, Ru and Fe surface contents that closely follow that expected from their bulk composition, indicating that there is no surface enrichment in any of the elements. In the as-milled state, more than 90% of Ti and Fe atoms are in the highest possible oxidation state, while Ru is in the metallic state. Following immersion of the samples in an oxidizing chlorate electrolyte, the Ru surface concentration decreases by a factor of two. This is also accompanied by an increase in the oxidation state of the Ru atoms left at the surface from 0 to +4. From a comparison between the Ru 3 d5/2,3/2 core level spectra of the electrodes with those of crystalline and hydrated RuO 2, it is postulated that dissolution and re-deposition of Ru in the form of hydrated RuO 2 occurs at open circuit potential in the chlorate electrolyte. The consequences of these findings for the electrocatalytic activity of the electrodes in chlorate electrolyte are finally discussed.

  17. HAER PA,35SCRAN,4F (sheet 1 of 1) Delaware, Lackawanna & ...

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

    HAER PA,35-SCRAN,4-F- (sheet 1 of 1) - Delaware, Lackawanna & Western Railroad, Scranton Yards, Scrap Platform, 350 feet South of South Washington Avenue & River Street, Scranton, Lackawanna County, PA

  18. FISH detection of Wolf-Hirschhorn syndrome: Exclusion of D4F26 as critical site

    SciTech Connect

    Johnson, V.P.; Altherr, M.R.; Blake, J.M.; Keppen, L.D.

    1994-08-01

    Wolf-Hirschhorn syndrome (WHS) is due to a deletion in the terminal band of 4p16.3. Among loci that have been involved in deletions are D4S95, D4S125, D4F26, as shown by PCR typing, Southern blot hybridization, and/or fluorescent in situ hybridization (FISH). Currently, FISH detection of WHS is predicated upon the deletion of the D4F26 locus with failure to hybridize to pC847.351, a commercially available cosmid probe. A WHS patient is shown to have an interstitial deletion, by hemizygosity at D4S98 and D4F26. This suggests that the tip of 4p, specifically D4F26, is not a critical deletion site for WHS. 19 refs., 4 figs.

  19. XPS characterization of polymer–monocalcium aluminate interface

    SciTech Connect

    Kalina, Lukáš Másilko, Jiří; Koplík, Jan; Šoukal, František

    2014-12-15

    The aim of this paper is the introduction of a sophisticated testing method, X-ray photoelectron spectroscopy (XPS), used to study the interface between the hydrated cement phase and polymer after mechanochemical activation, which is fundamental for the creation of macro-defect-free (MDF) composites. The XPS results clearly explain the hypothesis of a chemical reaction mechanism in the interphase regions affecting the final properties of the MDF materials.

  20. The Interpretation of XPS Spectra: Insights Into Materials Properties

    SciTech Connect

    Bagus, Paul S.; Ilton, Eugene S.; Nelin, Constance J.

    2013-06-01

    We review basic and advanced concepts needed for the correct analysis of XPS features. We place these concepts on rigorous foundations and explore their physical and chemical meanings without stressing the derivation of the mathematical formulations, which can be found in the cited literature. The significance and value of combining theory and experiment is demonstrated by discussions of the physical and chemical origins of the main and satellite XPS features for a variety of molecular and condensed phase materials.

  1. Correlation and relativistic effects for the 4f-nl and 5p-nl multipole transitions in Er-like tungsten

    SciTech Connect

    Safronova, U. I.; Safronova, A. S.

    2011-07-15

    Wavelengths, transition rates, and line strengths are calculated for the multipole (E1, M1, E2, M2, E3, and M3) transitions between the excited [Cd]4f{sup 13}5p{sup 6}nl, [Cd]4f{sup 14}5p{sup 5}nl configurations and the ground [Cd]4f{sup 14}5p{sup 6} state in Er-like W{sup 6+} ion ([Cd]=[Kr]4d{sup 10}5s{sup 2}). In particular, the relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate energies and transition rates for multipole transitions in this hole-particle system. This method is based on the relativistic many-body perturbation theory that agrees with multiconfiguration Dirac-Fock (MCDF) calculations in lowest order, and includes all second-order correlation corrections and corrections from negative-energy states. The calculations start from a [Cd]4f{sup 14}5p{sup 6} Dirac-Fock (DF) potential. First-order perturbation theory is used to obtain intermediate-coupling coefficients, and second-order RMBPT is used to determine the multipole matrix elements needed for calculations of other atomic properties such as line strengths and transition rates. In addition, core multipole polarizability is evaluated in random-phase and DF approximations. The comparison with available data is demonstrated.

  2. Calculation of Thermodynamic Functions of Fluorammonium Complexes of 4 f Elements

    NASA Astrophysics Data System (ADS)

    Malinovskaya, T. D.; Nefedov, R. A.; Sachkov, V. I.

    2013-12-01

    Theoretical estimates are made of the thermodynamic functions of fluorammonium complexes of 4 f elements. Using techniques of statistical thermodynamics, we have obtained the temperature dependences of the basic thermodynamic state functions ( C p , ∆ H, ∆ S, and ∆ G). The decomposition temperatures of the investigated complex fluorides of 4 f elements have been estimated on the basis of an analysis of the obtained dependences.

  3. Acetate- and thiol-capped monodisperse ruthenium nanoparticles: XPS, XAS, and HRTEM studies.

    PubMed

    Chakroune, Nassira; Viau, Guillaume; Ammar, Souad; Poul, Laurence; Veautier, Delphine; Chehimi, Mohamed M; Mangeney, Claire; Villain, Françoise; Fiévet, Fernand

    2005-07-19

    Monodisperse ruthenium nanoparticles were prepared by reduction of RuCl3 in 1,2-propanediol. The mean particle size was controlled by appropriate choice of the reduction temperature and the acetate ion concentration. Colloidal solutions in toluene were obtained by coating the metal particles with dodecanethiol. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XANES and EXAFS for the Ru K-absorption edge) were performed on particles of two different diameters, 2 and 4 nm, and in different environments, polyol/acetate or thiol. For particles stored in polyol/acetate XPS studies revealed superficial oxidation limited to one monolayer and a surface coating containing mostly acetate ions. Analysis of the EXAFS spectra showed both oxygen and ruthenium atoms around the ruthenium atoms with a Ru-Ru coordination number N smaller than the bulk value, as expected for fine particles. In the case of 2 nm acetate-capped particles N is consistent with particles made up of a metallic core and an oxidized monolayer. For 2 nm thiol-coated particles, a Ru-S bond was evidenced by XPS and XAS. For the 4 nm particles XANES and XPS studies showed that most of the ruthenium atoms are in the zerovalent state. Nevertheless, in both cases, when capped with thiol, the Ru-Ru coordination number inferred from EXAFS is much smaller than for particles of the same size stored in polyol. This is attributed to a structural disorganization of the particles by thiol chemisorption. HRTEM studies confirm the marked dependence of the structural properties of the ruthenium particles on their chemical environment; they show the acetate-coated particles to be single crystals, whereas the thiol-coated particles appear to be polycrystalline. PMID:16008388

  4. Hyperfine structure of the 4f85d6s2 configuration of the Tb atom

    NASA Astrophysics Data System (ADS)

    Furmann, B.; Stefanska, D.; Krzykowski, A.

    2015-09-01

    In this work, A and B hyperfine structure constants of electronic levels belonging to the configuration 4f85d6s2 of the terbium atom are presented, obtained via investigation of the hyperfine structure of 42 spectral lines, performed with the method of laser-induced fluorescence (LIF) in a hollow cathode discharge. Results for 14 of the investigated levels belonging to the configuration 4f85d6s2 were obtained for the first time. Also results concerning the hyperfine structure of 29 levels, involved in the transitions as upper levels, are presented. For these levels, almost all the results were obtained for the first time. On the basis of the results obtained within this work and those known from the literature, parametrization of the hyperfine structure was performed. The determined values of one-electron parameters for configuration 4f85d6s2 were compared to the values known from literature, determined so far on the basis of a much lower number of electronic levels. Values of relativistic radial integrals of the hyperfine structure for electrons 4f and 5d of the configuration 4f85d6s2 were calculated with the use of the MCDF code. The comparison of radial integrals calculated semi-empirically with those determined with MCDF method yielded an estimate of the values of configuration interaction parameters in the case of both magnetic dipole and electric quadrupole interactions of the terbium atom.

  5. TARGETING THE eIF4F TRANSLATION INITIATION COMPLEX: A CRITICAL NEXUS FOR CANCER DEVELOPMENT

    PubMed Central

    Pelletier, Jerry; Graff, Jeremy; Ruggero, Davide; Sonenberg, Nahum

    2014-01-01

    Elevated protein synthesis is an important feature of many cancer cells and often arises as a consequence of increased signaling flux channeled to eukaryotic initiation factor (eIF) 4F, the key regulator of the mRNA-ribosome recruitment phase of translation initiation. In many cellular and pre-clinical models of cancer, eIF4F deregulation results in changes in translational efficiency of specific mRNA classes. Importantly, many of these mRNAs code for proteins that potently regulate critical cellular processes such as cell growth and proliferation, enhanced cell survival, and cell migration that ultimately impinge on several hallmarks of cancer, including increased angiogenesis, deregulated growth control, enhanced cellular survival, epithelial-to-mesenchymal transition, invasion and metastasis. By being positioned as the molecular nexus downstream of key oncogenic signaling pathways (e.g. Ras, PI3K/AKT/TOR, and Myc), eIF4F serves as a direct link between important steps in cancer development and translation initiation. Identification of mRNAs particularly responsive to elevated eIF4F activity that typifies tumorigenesis underscores the critical role of eIF4F in cancer and raises the exciting possibility of developing new-in-class small molecules targeting translation initiation as anti-neoplastic agents. PMID:25593033

  6. Field ionization process of Eu 4f76snp Rydberg states

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Shen, Li; Dai, Chang-Jian

    2015-11-01

    The field ionization process of the Eu 4f76snp Rydberg states, converging to the first ionization limit, 4f76s 9S4, is systematically investigated. The spectra of the Eu 4f76snp Rydberg states are populated with three-step laser excitation, and detected by electric field ionization (EFI) method. Two different kinds of the EFI pulses are applied after laser excitation to observe the possible impacts on the EFI process. The exact EFI ionization thresholds for the 4f76snp Rydberg states can be determined by observing the corresponding EFI spectra. In particular, some structures above the EFI threshold are found in the EFI spectra, which may be interpreted as the effect from black body radiation (BBR). Finally, the scaling law of the EFI threshold for the Eu 4f76snp Rydberg states with the effective quantum number is built. Project supported by the National Natural Science Foundation of China (Grant Nos. 11004151 and 11174218).

  7. Pou4f2 knock-in Cre mouse: A multifaceted genetic tool for vision researchers

    PubMed Central

    Simmons, Aaron B.; Bloomsburg, Samuel J.; Billingslea, Samuel A.; Merrill, Morgan M.; Li, Shuai; Thomas, Marshall W.

    2016-01-01

    Purpose: A transgenic mouse that expresses Cre recombinase under control of the Pou4f2-promoter (also referred to as Brn-3b and Brn-3.2) was characterized. Pou4f2 expression has been reported in a subset of retinal ganglion cells (RGCs) in the retina, in the midbrain, and in the germline. In this study, we characterize the expression pattern of this Cre-recombinase line and report its utility in targeted deletion, temporal deletion, RGC depletion, and germline targeting, which can be regulated by the sex of the Cre-carrying mouse. Methods: Pou4f2Cre was mapped by using a combination of PCR and sequencing of PCR products to better understand the construct and to locate where it was inserted within the Pou4f2 locus. Cre expression patterns were examined by crossing Pou4f2Cre/+ mice to Cre reporter mice. Immunohistochemistry was used to further define the pattern of Cre expression and Cre-mediated recombination within the retina, brain, and other tissues. Results: An internal ribosome entry site (IRES)-Cre cassette was inserted into the Pou4f2 gene disrupting normal gene function, as verified by the depletion of RGCs in mice homozygous for the insert. Pou4f2Cre expression was observed in the retina, brain, peripheral neurons, and male germ cells. Germline recombination was observed when the sire carried the Cre and the target for recombination. In all other breeding schemes, recombination was observed within subsets of cells within the retina, brain, intestines, heart, and gonads. In the retina, Cre efficiently targets recombination in neurons within the RGC layer (RGL), the inner nuclear layer (INL), and a small percentage of photoreceptors, activity that has not been previously reported. Unlike most other Cre lines active in the inner retina, recombination in Müller and other glia was not observed in mice carrying Pou4f2Cre. Within the visual centers of the brain, Cre targets recombination in about 15% of cells within the superchiasmatic nucleus, lateral geniculate

  8. XPS characterization scheme for phase-pure epitaxial NbO2

    NASA Astrophysics Data System (ADS)

    Hadamek, Tobias; Posadas, Agham; Demkov, Alex

    NbO2 shows a semiconductor-to-metal transition with an associated structural transition of Peierls type. NbO2 and Nb2O5 or mixtures thereof have also shown electrically induced insulator-to-metal transitions. To shed light on the nature of the electrically induced insulator-to-metal transition it is important to grow high phase purity NbO2 and Nb2O5 and compare electrical measurements with mixed niobium oxides and with different electrode materials. Processing NbO2 and avoiding surface oxidation requires ultra-high vacuum (UHV) conditions. Niobium oxide thin films where grown in UHV by molecular beam epitaxy on 111-oriented STO substrates and analyzed by X-ray photoelectron spectroscopy (XPS). It was shown that the NbO2 3d core level spectrum exhibits an asymmetric spin-orbit peak pair with more spectral weight on the high binding energy side. Based on the shape of the Nb 3d core levels, peak positions relative to the oxygen O 1s peak, and the valence band shape and height ratio of the niobium 4dxy split-off band to the oxygen 2p band, an identification scheme for NbO2 by XPS was devised. Complementary the NbO2 phase was confirmed by reflection high-energy electron and x-ray diffraction analysis.

  9. AES XPS study of chromium carbides and chromium iron carbides

    NASA Astrophysics Data System (ADS)

    Detroye, M.; Reniers, F.; Buess-Herman, C.; Vereecken, J.

    1999-04-01

    The nature of chromium rich carbides which precipitate at grain boundaries in steels is still not perfectly understood. We performed a multitechnique approach on model chromium carbide and chromium-iron carbide samples: Auger Electron Spectroscopy (AES), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), and High Energy Electron Diffraction (HEED) were used to characterise the samples. Significant chemical shifts were observed for the Cr, Fe and C XPS peaks in the M 7C 3 compound (M stands for metal), indicating unambiguously that the compound formed is a mixed iron-chromium carbide.

  10. Characterization of fossil remains using XRF, XPS and XAFS spectroscopies

    NASA Astrophysics Data System (ADS)

    Zougrou, I. M.; Katsikini, M.; Pinakidou, F.; Brzhezinskaya, M.; Papadopoulou, L.; Vlachos, E.; Tsoukala, E.; Paloura, E. C.

    2016-05-01

    Synchrotron radiation micro-X-Ray Fluorescence (μ-XRF), X-ray photoelectron (XPS) and X-ray Absorption Fine Structure (XAFS) spectroscopies are applied for the study of paleontological findings. More specifically the costal plate of a gigantic terrestrial turtle Titanochelon bacharidisi and a fossilized coprolite of the cave spotted hyena Crocuta crocuta spelaea are studied. Ca L 2,3-edge NEXAFS and Ca 2p XPS are applied for the identification and quantification of apatite and Ca containing minerals. XRF mapping and XAFS are employed for the study of the spatial distribution and speciation of the minerals related to the deposition environment.

  11. Substituting mouse transcription factor Pou4f2 with a sea urchin orthologue restores retinal ganglion cell development

    PubMed Central

    Mocko-Strand, Julie A.; Wang, Jing; Ullrich-Lüter, Esther; Pan, Ping; Wang, Steven W.; Arnone, Maria Ina; Frishman, Laura J.; Klein, William H.

    2016-01-01

    Pou domain transcription factor Pou4f2 is essential for the development of retinal ganglion cells (RGCs) in the vertebrate retina. A distant orthologue of Pou4f2 exists in the genome of the sea urchin (class Echinoidea) Strongylocentrotus purpuratus (SpPou4f1/2), yet the photosensory structure of sea urchins is strikingly different from that of the mammalian retina. Sea urchins have no obvious eyes, but have photoreceptors clustered around their tube feet disc. The mechanisms that are associated with the development and function of photoreception in sea urchins are largely unexplored. As an initial approach to better understand the sea urchin photosensory structure and relate it to the mammalian retina, we asked whether SpPou4f1/2 could support RGC development in the absence of Pou4f2. To answer this question, we replaced genomic Pou4f2 with an SpPou4f1/2 cDNA. In Pou4f2-null mice, retinas expressing SpPou4f1/2 were outwardly identical to those of wild-type mice. SpPou4f1/2 retinas exhibited dark-adapted electroretinogram scotopic threshold responses, indicating functionally active RGCs. During retinal development, SpPou4f1/2 activated RGC-specific genes and in S. purpuratus, SpPou4f2 was expressed in photoreceptor cells of tube feet in a pattern distinct from Opsin4 and Pax6. Our results suggest that SpPou4f1/2 and Pou4f2 share conserved components of a gene network for photosensory development and they maintain their conserved intrinsic functions despite vast morphological differences in mouse and sea urchin photosensory structures. PMID:26962139

  12. Substituting mouse transcription factor Pou4f2 with a sea urchin orthologue restores retinal ganglion cell development.

    PubMed

    Mao, Chai-An; Agca, Cavit; Mocko-Strand, Julie A; Wang, Jing; Ullrich-Lüter, Esther; Pan, Ping; Wang, Steven W; Arnone, Maria Ina; Frishman, Laura J; Klein, William H

    2016-03-16

    Pou domain transcription factor Pou4f2 is essential for the development of retinal ganglion cells (RGCs) in the vertebrate retina. A distant orthologue of Pou4f2 exists in the genome of the sea urchin (class Echinoidea) Strongylocentrotus purpuratus (SpPou4f1/2), yet the photosensory structure of sea urchins is strikingly different from that of the mammalian retina. Sea urchins have no obvious eyes, but have photoreceptors clustered around their tube feet disc. The mechanisms that are associated with the development and function of photoreception in sea urchins are largely unexplored. As an initial approach to better understand the sea urchin photosensory structure and relate it to the mammalian retina, we asked whether SpPou4f1/2 could support RGC development in the absence of Pou4f2. To answer this question, we replaced genomic Pou4f2 with an SpPou4f1/2 cDNA. In Pou4f2-null mice, retinas expressing SpPou4f1/2 were outwardly identical to those of wild-type mice. SpPou4f1/2 retinas exhibited dark-adapted electroretinogram scotopic threshold responses, indicating functionally active RGCs. During retinal development, SpPou4f1/2 activated RGC-specific genes and in S. purpuratus, SpPou4f2 was expressed in photoreceptor cells of tube feet in a pattern distinct from Opsin4 and Pax6. Our results suggest that SpPou4f1/2 and Pou4f2 share conserved components of a gene network for photosensory development and they maintain their conserved intrinsic functions despite vast morphological differences in mouse and sea urchin photosensory structures. PMID:26962139

  13. TEM and XPS studies on CdS/CIGS interfaces

    NASA Astrophysics Data System (ADS)

    Han, Jun-feng; Liao, Cheng; Cha, Li-mei; Jiang, Tao; Xie, Hua-mu; Zhao, Kui; Besland, M.-P.

    2014-12-01

    Copper indium gallium selenide (CIGS) was deposited by metallic precursors sputtering and subsequently submitted to a selenization process. The upper CdS layers were deposited by chemical bath deposition (CBD) technique. The CdS/CIGS interfaces were investigated by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). As checked by XPS analysis, the CIGS surface exhibited a hydroxide-terminated CdSe layer when treated with Cd Partial Electrolyte solution (Cd PE). Its thickness was roughly estimated to several nanometers. A 100 nm thick CdS layer was deposited onto CIGS surface. The TEM images revealed a clear and sharp interface between CdS and CIGS. XPS analysis showed a CIGS surface covered by a pinhole free and homogeneous CdS layer. XPS depth profile measurement of the CdS/CIGS interface did not evidence elemental inter-diffusion between the CIGS and CdS layers, in very good agreement with TEM observations.

  14. XPS analysis of nikki N111 catalyst pellets

    SciTech Connect

    Kelly, Dan

    2007-03-26

    X-ray photoelectron spectroscopy (XPS) was performed on several pellets of Nikki N111 catalyst to determine elemental composition. Of specific interest, the Nikki MSDS for this material cites a 20 wt. % contribution from the species "Others". XPS was employed to determine more precisely the chemical composition of the pellets and search for potential catalytic metal species not identified on the MSDS. Results are tabulated in Table 1 below. XPS analysis of the chemical composition of the catalyst pellets compares favorably to the N ikki MSDS, if the assumption is made that the nickel in the catalyst is oxidized to Ni2O3. Specifically, using a 100 g sample basis, the 49 grams of nickel metal specified in the MSDS would carry 20 grams of oxygen if it were oxidized to Ni2O3, potentially accounting for the 20 wt. %"Others". XPS was able to confirm the presence of copper and chromium in the pellets, each expected at less than 1 atomic percent and quantified at 1-3 atomic percent concentrations, but no metal species not identified by the MSDS were detected.

  15. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage § 55.5 Coverage...

  16. Multi-cations doped LiVPO4F cathode for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Sun, Xiaofei; Xu, Youlong; Teng, Feng; Sun, Gongyu; Chen, Yanjun; Chen, Guogang

    2015-05-01

    The multi-cations doped LiVPO4F, nominally Li0.97Cr0.01V0.95Al0.01Nb0.02PO4F0.97, is prepared by Chromium (Cr) doping on lithium site and Al-Nb co-doping on vanadium site via a conventional carbothermal reduction (CTR) route. The crystallographic lattice volume, particle size and morphology are not obviously changed comparing with un-doped LiVPO4F. However, the high rate and lifetime cycling performances are noticeably improved although the capacities at very low currents are slightly decreased. The reversible capacity at 1/10 C, 1 C, 2 C and 4 C of the pristine LiVPO4F is 143 mA h g-1, 99 mA h g-1, 86 mA h g-1 and 70 mA h g-1, respectively, while that of the doped counterpart is 138 mA h g-1, 102 mA h g-1, 95 mA h g-1 and 82 mA h g-1, respectively. The capacity retention after 100 galvanostatic cycles at 1.5 C is enhanced from 85.4% to 90.9% by such multi-cations doping. Moreover, the initial coulombic efficiency is significantly increased from 81.8% to 90.3% as well.

  17. 28 CFR 55.5 - Coverage under section 4(f)(4).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Coverage under section 4(f)(4). 55.5 Section 55.5 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage § 55.5 Coverage...

  18. System design of programmable 4f phase modulation techniques for rapid intensity shaping: a conceptual comparison

    NASA Astrophysics Data System (ADS)

    Roth, Matthias; Heber, Jörg; Janschek, Klaus

    2016-03-01

    The present study analyses three beam shaping approaches with respect to a light-efficient generation of i) patterns and ii) multiple spots by means of a generic optical 4f-setup. 4f approaches share the property that due to the one-to-one relationship between output intensity and input phase, the need for time-consuming, iterative calculation can be avoided. The resulting low computational complexity offers a particular advantage compared to the widely used holographic principles and makes them potential candidates for real-time applications. The increasing availability of high-speed phase modulators, e.g. on the basis of MEMS, calls for an evaluation of the performances of these concepts. Our second interest is the applicability of 4f methods to high-power applications. We discuss the variants of 4f intensity shaping by phase modulation from a system-level point of view which requires the consideration of application relevant boundary conditions. The discussion includes i) the micro mirror based phase manipulation combined with amplitude masking in the Fourier plane, ii) the Generalized Phase Contrast, and iii) matched phase-only correlation filtering combined with GPC. The conceptual comparison relies on comparative figures of merit for energy efficiency, pattern homogeneity, pattern image quality, maximum output intensity and flexibility with respect to the displayable pattern. Numerical simulations illustrate our findings.

  19. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false F.o.b. destination... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-4 F.o.b. destination solicitations. (a) When preparing f.o.b destination solicitations, the contracting officer shall refer to...

  20. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false F.o.b. destination... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-4 F.o.b. destination solicitations. (a) When preparing f.o.b destination solicitations, the contracting officer shall refer to...

  1. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) The cost of transportation... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin,...

  2. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false F.o.b. origin, freight prepaid. 47.303-4 Section 47.303-4 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term....

  3. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false F.o.b. destination... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-4 F.o.b. destination solicitations. (a) When preparing f.o.b destination solicitations, the contracting officer shall refer to...

  4. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false F.o.b. destination... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-4 F.o.b. destination solicitations. (a) When preparing f.o.b destination solicitations, the contracting officer shall refer to...

  5. 48 CFR 47.305-4 - F.o.b. destination solicitations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false F.o.b. destination... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.305-4 F.o.b. destination solicitations. (a) When preparing f.o.b destination solicitations, the contracting officer shall refer to...

  6. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) The cost of transportation... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin,...

  7. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) The cost of transportation... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin,...

  8. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Administration prescribes commercial zones at Subpart B of 49 CFR part 372); and (2) The cost of transportation... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false F.o.b. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin,...

  9. 77 FR 64836 - Notice of Availability of Draft Environmental Impact Statement (DEIS), Draft Section 4(f...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-23

    ...) are cooperating agencies, by virtue of their jurisdictional authority and/or resource management... . The FAA encourages all interested parties to provide comments concerning the scope and content of the...), Draft Section 4(f) Evaluation, Notice of ANILCA Title XI evaluation, and Notice of Public Comment...

  10. Human Enteric Microsomal CYP4F Enzymes O-Demethylate the Antiparasitic Prodrug Pafuramidine

    PubMed Central

    Wang, Michael Zhuo; Wu, Judy Qiju; Bridges, Arlene S.; Zeldin, Darryl C.; Kornbluth, Sally; Tidwell, Richard R.; Hall, James Edwin; Paine, Mary F.

    2008-01-01

    CYP4F enzymes, including CYP4F2 and CYP4F3B, were recently shown to be the major enzymes catalyzing the initial oxidative O-demethylation of the antiparasitic prodrug pafuramidine (DB289) by human liver microsomes. As suggested by a low oral bioavailability, DB289 could undergo first-pass biotransformation in the intestine, as well as in the liver. Using human intestinal microsomes (HIM), we characterized the enteric enzymes that catalyze the initial O-demethylation of DB289 to the intermediate metabolite, M1. M1 formation in HIM was catalyzed by cytochrome P450 (P450) enzymes, as evidenced by potent inhibition by 1-aminoben-zotriazole and the requirement for NADPH. Apparent Km and Vmax values ranged from 0.6 to 2.4 μM and from 0.02 to 0.89 nmol/min/mg protein, respectively (n = 9). Of the P450 chemical inhibitors evaluated, ketoconazole was the most potent, inhibiting M1 formation by 66%. Two inhibitors of P450-mediated arachidonic acid metabolism, HET0016 (N-hydroxy-N′-(4-n-butyl-2-methylphenyl)formamidine) and 17-octadecynoic acid, inhibited M1 formation in a concentration-dependent manner (up to 95%). Immunoinhibition with an antibody raised against CYP4F2 showed concentration-dependent inhibition of M1 formation (up to 92%), whereas antibodies against CYP3A4/5 and CYP2J2 had negligible to modest effects. M1 formation rates correlated strongly with arachidonic acid ω-hydroxylation rates (r2 = 0.94, P < 0.0001, n = 12) in a panel of HIM that lacked detectable CYP4A11 protein expression. Quantitative Western blot analysis revealed appreciable CYP4F expression in these HIM, with a mean (range) of 7 (3–18) pmol/mg protein. We conclude that enteric CYP4F enzymes could play a role in the first-pass biotransformation of DB289 and other xenobiotics. PMID:17709372

  11. A dual-emitting 4d-4f nanocrystalline metal-organic framework as a self-calibrating luminescent sensor for indoor formaldehyde pollution

    NASA Astrophysics Data System (ADS)

    Hao, Ji-Na; Yan, Bing

    2016-06-01

    A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag+ ions can tune the dual-emissive characters of the material. FA can interact with the Ag+ ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection.A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag+ ions can tune the dual-emissive characters of the material. FA can interact with the Ag+ ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection. Electronic supplementary information (ESI) available: Experimental procedure, N2 adsorption-desorption isotherms, IR spectra, EDX mappings, ICP data, luminescence data, PXRD patterns, UV-Vis spectra, and XPS spectra. See DOI: 10.1039/c6nr02446g

  12. XPS and XRF depth patina profiles of ancient silver coins

    NASA Astrophysics Data System (ADS)

    Caridi, F.; Torrisi, L.; Cutroneo, M.; Barreca, F.; Gentile, C.; Serafino, T.; Castrizio, D.

    2013-05-01

    Ancient silver coins of different historical periods going from IV cent. B.C. up to recent XIX century, coming from different Mediterranean countries have been investigated with different surface physical analyses. X-ray photoelectron spectroscopy (XPS) analysis has been performed by using electron emission induced by 1.4 keV X-rays. X-ray fluorescence (XRF) analysis has been devoted by using 30 keV electron beam. Scanning electron microscopy (SEM) has been employed to analyze the surface morphology and the X-ray map distribution by using a 30 keV microbeam. Techniques were used to investigate about the patina composition and trace elements as a function of the sample depth obtained coupling XPS to 3 keV argon ion sputtering technique.

  13. ToF-SIMS and XPS study of ancient papers

    NASA Astrophysics Data System (ADS)

    Benetti, Francesca; Marchettini, Nadia; Atrei, Andrea

    2011-01-01

    The surface composition of 18th century papers was investigated by means of ToF-SIMS and XPS. The aim of the present study was to explore the possibility of using these surface sensitive methods to obtain information which can help to determine the manufacturing process, provenance and state of conservation of ancient papers. The ToF-SIMS results indicate that the analyzed papers were sized by gelatin and that alum was added as hardening agent. The paper sheets produced in near geographical areas but in different paper mills exhibit a similar surface composition and morphology of the fibers as shown by the ToF-SIMS measurements. The ToF-SIMS and the XPS results indicate that a significant fraction of the cellulose fibers is not covered by the gelatin layer. This was observed for the ancient papers and for a modern handmade paper manufactured according to the old recipes.

  14. XPS and IGC characterization of steam treated triticale straw

    NASA Astrophysics Data System (ADS)

    Zhao, Liyan; Boluk, Yaman

    2010-10-01

    The surface chemical composition and surface energy of native and steam treated triticale straws have been investigated by X-ray photoelectron spectroscopy (XPS) and inverse gas chromatography (IGC) to reveal the effect of steam treatment temperature and time. The XPS results show that the contents of C elements and C-C group on the exterior surface of native triticale straw are much higher than those on the interior surface, indicating that there was a high quantity of wax on the exterior surface of the native triticale straw. Upon steam treatment, both carbon levels and C-C groups reduce with increasing steam temperature and treatment time of the exterior surfaces. However, the effect of steam treatment on the interior surface is very limited. In terms of the surface acid and base properties, the steam treated samples exhibited higher acid and base properties than the native sample, indicating a more polar surface of the steam treated sample.

  15. Near-ambient XPS characterization of interfacial copper species in ceria-supported copper catalysts.

    PubMed

    Monte, Manuel; Munuera, Guillermo; Costa, Dominique; Conesa, José C; Martínez-Arias, Arturo

    2015-11-28

    Catalysts based on combinations of copper and cerium oxides are interesting alternatives to noble metal ones for processes involved in the production/purification of hydrogen produced from hydrocarbons or biomass like the water-gas shift or the preferential oxidation of CO reactions. Active sites for such processes have been proposed to correspond to reduced species formed at the interface between both oxides. The present work provides direct evidence of reduced copper species located at the interface and observed during the course of near-ambient XPS experiments performed over samples of copper oxide supported on ceria nanospheres and nanocubes subjected to interaction with CO at different temperatures. The analysis of XPS results is based on DFT+U calculations employed as a complementary method for the analysis of redox properties of the catalysts and core-level shifts produced upon such redox changes. Differences observed in interfacial redox properties as a function of the ceria support morphology appear to be most useful to explain catalytic properties of this type of system for mentioned processes. PMID:26497369

  16. Silicon Surface Modification Using C4F8+O2 Plasma for Nano-Imprint Lithography.

    PubMed

    Lee, Junmyung; Efremov, Alexander; Lee, Jaemin; Yeom, Geun Young; Kwon, Kwang-Ho

    2015-11-01

    The investigation of C4F8+O2 feed gas composition on both plasma parameters and plasma treated silicon surface characteristics was carried out. The combination of plasma diagnostics by Langmuir probes and plasma modeling indicated that an increase in O2 mixing ratio results in monotonically decreasing densities of CF(x) (x = 1-3) radicals as well as in non-monotonic behavior of F atom density. The surface characterization by X-ray photoelectron spectroscopy and contact angle measurements showed that the C4F8+O2 mixtures with less than 60% 02 result in modification of Si surfaces due to the deposition of the FC polymer films while the change of O2 mixing ratio in the range of 30%-60% provides an effective adjustment of the surface characteristics such as surface energy, contact angle, etc. PMID:26726589

  17. Photochromism and Photomagnetism of a 3d-4f Hexacyanoferrate at Room Temperature.

    PubMed

    Cai, Li-Zhen; Chen, Qing-Song; Zhang, Cui-Juan; Li, Pei-Xin; Wang, Ming-Sheng; Guo, Guo-Cong

    2015-09-01

    Polycyanometallate compounds with both photochromism and photomagnetism have appealing applications in optical switches and memories, but such optical behaviors were essentially restricted to the cryogenic temperature. We realized, for the first time, the photochromism and photomagnetism of 3d-4f hexacyanoferrates at room temperature (RT) in [Eu(III)(18C6)(H2O)3]Fe(III)(CN)6·2H2O (18C6 = 18-crown-6). Photoinduced electron transfer (PET) from crown to Fe(III) yields long-lived charge-separated species at RT in air in the solid state and also weakens the magnetic susceptibility significantly. The PET mechanism and changing trend of photomagnetism differ significantly from those reported for known 3d-4f hexacyanoferrates. This work not only develops a new type of inorganic-organic hybrid photochromic material but opens a new avenue for RT photomagnetic polycyanometallate compounds. PMID:26284651

  18. Thermodynamic Properties of 4f- and 5f-SHELL Metals at Finite Temperatures:

    NASA Astrophysics Data System (ADS)

    Bhatt, N. K.; Vyas, P. R.; Jani, A. R.; Gohel, V. B.

    The thermodynamic properties of 4f- and 5f-shell metals have been studied at high temperatures using mean-field potential approach. The MFP seen by the lattice ion is constructed in terms of the total energy-volume relation using local pseudopotentials due to Pandya et al. [Physica B 307, 138 (2001)]. We have calculated static compression, shock-wave compression, volume thermal expansion, isothermal and adiabatic bulk moduli (BT and BS), specific heats (CV and CP), thermodynamic Grüneisen parameter (γth), anharmonic contribution to the specific heat and temperature along shock Hugoniot for 4f (γ-Ce)- and 5f (fcc-Th)-shell metals. The results are well compared with the other theoretical and experimental findings, which ensure the use of pseudopotentials for studying thermodynamic properties at higher temperatures in case of lanthanides and actinides.

  19. The C 4F 10 Cherenkov detector for DIRAC-II

    NASA Astrophysics Data System (ADS)

    Horikawa, S.; Allkofer, Y.; Amsler, C.; Brekhovskikh, V.; Kuptsov, A.; Pentia, M.; Zhabitsky, M.

    2008-09-01

    A new threshold Cherenkov detector using C 4F 10 gas radiator was built and put into operation in the DIRAC-II experiment at CERN. Running on the C 4F 10 at room temperature and atmospheric pressure, the detector discriminates between pions and kaons in the momentum range of 4- 8 GeV/c. A compact radiator-gas recirculation system including a gas-liquid separation unit, hollow-fibre membranes and molecular sieves ensures gas purity for a long term of operation without a significant loss of the gas. The system is robust and stable and the pressure in the two detector vessels is regulated in the range of ±0.5 mbar. We report on the design and the technical aspects of the detector and its response in the DIRAC 2007 run.

  20. Competition between 3d and 4f magnetism in Ce2Fe2S5

    NASA Astrophysics Data System (ADS)

    Schneidewind, A.; Mills, A. M.; Schnelle, W.; Stockert, O.; Ouladdiaf, B.; Ruck, M.

    2007-03-01

    Magnetic susceptibility measurements and neutron powder diffraction were performed on the rare-earth transition-metal sulfide Ce2Fe2S5 to study the effect of the substitution of nonmagnetic La(4f0) by Ce4f1). Ce2Fe2S5, which is isostructural to La2Fe2S5, contains Fe ions within chains of iron-sulfur octahedra and tetrahedra that are interconnected by Ce ions. Two antiferromagnetic phases, both with the propagation vector τ=({1}/{2} {1}/{2} 0), are observed: at 5 K⩽T⩽80 K ordering of the Fe moments is found; at T⩽5 K the Ce ions also participate in the magnetic ordering.

  1. Standard Test Data and Peak Fitting for XPS Measurements

    National Institute of Standards and Technology Data Gateway

    Standard Test Data and Peak Fitting for XPS Measurements (Web, free access)   This web site provides an extensive set of simulated photoelectron spectroscopy data for users to test software for determining the positions and intensities of overlapping peaks. Users download the data, perform their analyses, and then upload their results. A Java program evaluates the results and provides a graphical presentation of the errors in the user's analyses.

  2. Extended analysis of the 5g. -->. 4f emissions in H/sub 2/

    SciTech Connect

    Chang, E.S.; Pulchtopek, S.; Eyler, E.E.

    1984-01-15

    An analysis starting from Hund's case d has been used to extend the work of Herzberg and Jungen on the 5g..-->..4f emissions in H/sub 2/. A simple analytical expression for the line intensities is presented that agrees with their calculations is about 1%. All of the experimentally observed lines have been accounted for by including higher vibrational levels in our calculations.

  3. XPS Study of Plasma- and Argon Ion-Sputtered Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Kliss, Mark (Technical Monitor)

    1997-01-01

    The similarity of plasma-polymerized tetrafluoroethylene (PPTFE) and the fluoropolymer film deposited by rf (radio frequency) plasma sputtering (SPTFE) of polytetrafluoroethylene (PTFE), noted earlier in the literature, has been reconfirmed. FT-IR (Fourier Transform Infrared), XPS (X ray Photoelectron Spectroscopy) and UV (ultraviolet) spectroscopy has been employed in apparently the first study to involve preparation of PPTFE and SPTFE in the same reactor and under comparable low-power plasma conditions. Most of the work concerned the use of He or Ar as sputtering gas, but some runs were also carried out with the other rare gases Ne, Kr and Xe. The C1s XPS spectra of SPTFE films displayed a relatively higher content of CF2 groups, and yielded higher F/C (fluorine / carbon) ratios, than PPTFE films, while the SPTFE films were somewhat more transparent in the UV than PPTFE. The F/C ratios for SPTFE were essentially independent of the rare gas used for sputtering. Increasing rf power from 10 to 50 W for Xe plasma-sputtering of PTFE resulted in successively lower F/C ratios (1.55 to 1.21), accompanied by sputtering of the glass reactor occurring at 40 W and above. Some limited XPS, FT-IR and UV data are presented on Ar ion-sputtered PTFE.

  4. XPS characterization of the surface immobilization of antibacterial furanones

    NASA Astrophysics Data System (ADS)

    Al-Bataineh, Sameer A.; Britcher, Leanne G.; Griesser, Hans J.

    2006-02-01

    Brominated furanones have attracted recent interest as antibacterial compounds. To utilize them as protective coatings in biomedical device applications, they must be covalently immobilized onto solid surfaces; however, interfacial coupling protocols developed for other biomolecules are not applicable to furanones. An azide reaction scheme has enabled covalent immobilization onto fluorinated ethylene propylene copolymer but its chemistry is less predictable, requiring detailed characterization by XPS and tapping mode AFM after each step of the immobilization sequence. XPS curve fitting resolved components in the C 1s, N 1s and Br 3d regions. Angle dependent XPS was used to assess the depth distributions and layer thicknesses. The results indicated successful covalent immobilization of furanones; however, side reactions occurred. In addition to the expected C sbnd Br, a contribution from bromine ion (Br -) was detected, indicating that photo-degradation of furanones took place during UV illumination, and this reaction was found to increase with illumination time. The Br - was removed by washing with water, whereas the C sbnd Br signal from immobilized furanone remained. Spectroscopic characterization will assist in elucidating the structure of furanone coatings, understanding their mode of action when covalently immobilized on surfaces, and rationally designing and optimizing an effective antibacterial coating for biomedical applications.

  5. Monte Carlo simulation of electron swarm parameters in c-C{4}F{8}

    NASA Astrophysics Data System (ADS)

    Liu, X. L.; Xiao, D. M.

    2007-06-01

    Perfluorocyclobutane (c-C{4}F{8}) is one of the most promising gases to be used in gas mixtures, which are the candidates to substitute for SF{6} gas as high dielectric strength insulators with a reduced potential for global warming. The set of initial collision cross-sections are assembled and modified. The motion of electrons in c-C{4}F{8} in uniform electric fields is simulated using Monte Carlo method. Also the density-normalized ionization coefficients α /N, attachment coefficients η /N, the effective ionization coefficients (α -η)/N, drift velocity (Ve) and the electron longitudinal diffusion coefficient ({ND_L}) are calculated for the range of density-reduced electric field strength, 300 ≤slant E/N ≤slant 1000 Td. The electron swarm parameters of simulation are compared with experimental data and other results of simulation, which obtain a good agreement. However, further calculations and measurements for c-C{4}F{8}, such as η /N and {ND_L} are required.

  6. Utilizing 3d-4f magnetic interaction to slow the magnetic relaxation of heterometallic complexes.

    PubMed

    Li, Xiao-Lei; Min, Fan-Yong; Wang, Chao; Lin, Shuang-Yan; Liu, Zhiliang; Tang, Jinkui

    2015-05-01

    The synthesis, structural characterization, and magnetic properties of four related heterometallic complexes with formulas [Dy(III)2Co(II)(C7H5O2)8]·6H2O (1), [Dy(III)2Ni(II)(C7H5O2)8]·(C7H6O2)2 (2), Tb(III)2Co(II)(C7H5O2)8 (3), and Dy(III)2Cd(II)(C7H5O2)8 (4) were reported. Each of complexes has a perfectly linear arrangement of the metal ions with two terminal Ln(III) (Ln(III) = Dy(III), Tb(III)) ions and one central M(II) (M(II) = Co(II), Ni(II), Cd(II)) ion. It was found that 1-3 displayed obvious magnetic interactions between the spin carriers according to the direct current (dc) susceptibility measurements. Alternating current (ac) magnetic susceptibility measurements indicate that complexes 1-4 all exhibit single-molecule magnet (SMM) behavior, while the replacement of the diamagnetic Cd(II) by paramagnetic ions leads to a significant slowing of the relaxation thanks to the magnetic interactions between 3d and 4f ions, resulting in higher relaxation barrier for complexes 1 and 2. Moreover, both Dy2Co and Dy2Ni compounds exhibit dual relaxation pathways that may originate from the single ion behavior of individual Dy(III) ions and the coupling between Dy(III) and Co(II)/Ni(II) ions, respectively, which can be taken as the feature of 3d-4f SMMs. The Ueff for 1 of 127 K is a relatively high value among the reported 3d-4f SMMs. The results demonstrate that the magnetic coupling between 3d and 4f ions is crucial to optimize SMM parameters. The synthetic approach illustrated in this work represents an efficient route to design nd-4f based SMMs via incorporating suitable paramagnetic 3d and even 4d and 5d ions into the d-f system. PMID:25906391

  7. XPS/STM study of model bimetallic Pd-Au/HOPG catalysts

    NASA Astrophysics Data System (ADS)

    Bukhtiyarov, Andrey V.; Prosvirin, Igor P.; Bukhtiyarov, Valerii I.

    2016-03-01

    The preparation of model bimetallic Pd-Au/HOPG catalysts has been investigated using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) techniques. Initially, model "core-shell" type Pd-Au/HOPG catalysts with similar particle size distribution (5-8 nm), but with different densities of particle locations on the HOPG surface and Pd/Au atomic ratios are prepared. Further, their thermal stability is studied within a temperature range of 50-500 °C at UHV conditions. It has been shown that annealing the model catalysts at a temperature range of 300-400 °C leads to formation of Pd-Au alloyed particles. Enhancement of heating temperature up to 500 °C results in sintering of bimetallic nanoparticles. Contribution of different parameters controlling the properties of Pd-Au alloyed particles has been discussed.

  8. Flow Sorting and Sequencing Meadow Fescue Chromosome 4F1[C][W

    PubMed Central

    Kopecký, David; Martis, Mihaela; Číhalíková, Jarmila; Hřibová, Eva; Vrána, Jan; Bartoš, Jan; Kopecká, Jitka; Cattonaro, Federica; Stočes, Štěpán; Novák, Petr; Neumann, Pavel; Macas, Jiří; Šimková, Hana; Studer, Bruno; Asp, Torben; Baird, James H.; Navrátil, Petr; Karafiátová, Miroslava; Kubaláková, Marie; Šafář, Jan; Mayer, Klaus; Doležel, Jaroslav

    2013-01-01

    The analysis of large genomes is hampered by a high proportion of repetitive DNA, which makes the assembly of short sequence reads difficult. This is also the case in meadow fescue (Festuca pratensis), which is known for good abiotic stress resistance and has been used in intergeneric hybridization with ryegrasses (Lolium spp.) to produce Festulolium cultivars. In this work, we describe a new approach to analyze the large genome of meadow fescue, which involves the reduction of sample complexity without compromising information content. This is achieved by dissecting the genome to smaller parts: individual chromosomes and groups of chromosomes. As the first step, we flow sorted chromosome 4F and sequenced it by Illumina with approximately 50× coverage. This provided, to our knowledge, the first insight into the composition of the fescue genome, enabled the construction of the virtual gene order of the chromosome, and facilitated detailed comparative analysis with the sequenced genomes of rice (Oryza sativa), Brachypodium distachyon, sorghum (Sorghum bicolor), and barley (Hordeum vulgare). Using GenomeZipper, we were able to confirm the collinearity of chromosome 4F with barley chromosome 4H and the long arm of chromosome 5H. Several new tandem repeats were identified and physically mapped using fluorescence in situ hybridization. They were found as robust cytogenetic markers for karyotyping of meadow fescue and ryegrass species and their hybrids. The ability to purify chromosome 4F opens the way for more efficient analysis of genomic loci on this chromosome underlying important traits, including freezing tolerance. Our results confirm that next-generation sequencing of flow-sorted chromosomes enables an overview of chromosome structure and evolution at a resolution never achieved before. PMID:24096412

  9. Red nucleus and rubrospinal tract disorganization in the absence of Pou4f1

    PubMed Central

    Martinez-Lopez, Jesus E.; Moreno-Bravo, Juan A.; Madrigal, M. Pilar; Martinez, Salvador; Puelles, Eduardo

    2015-01-01

    The red nucleus (RN) is a neuronal population that plays an important role in forelimb motor control and locomotion. Histologically it is subdivided into two subpopulations, the parvocellular RN (pRN) located in the diencephalon and the magnocellular RN (mRN) in the mesencephalon. The RN integrates signals from motor cortex and cerebellum and projects to spinal cord interneurons and motor neurons through the rubrospinal tract (RST). Pou4f1 is a transcription factor highly expressed in this nucleus that has been related to its specification. Here we profoundly analyzed consequences of Pou4f1 loss-of-function in development, maturation and axonal projection of the RN. Surprisingly, RN neurons are specified and maintained in the mutant, no cell death was detected. Nevertheless, the nucleus appeared disorganized with a strong delay in radial migration and with a wider neuronal distribution; the neurons did not form a compacted population as they do in controls, Robo1 and Slit2 were miss-expressed. Cplx1 and Npas1, expressed in the RN, are transcription factors involved in neurotransmitter release, neuronal maturation and motor function processes among others. In our mutant mice, both transcription factors are lost, suggesting an abnormal maturation of the RN. The resulting altered nucleus occupied a wider territory. Finally, we examined RST development and found that the RN neurons were able to project to the spinal cord but their axons appeared defasciculated. These data suggest that Pou4f1 is necessary for the maturation of RN neurons but not for their specification and maintenance. PMID:25698939

  10. Red nucleus and rubrospinal tract disorganization in the absence of Pou4f1.

    PubMed

    Martinez-Lopez, Jesus E; Moreno-Bravo, Juan A; Madrigal, M Pilar; Martinez, Salvador; Puelles, Eduardo

    2015-01-01

    The red nucleus (RN) is a neuronal population that plays an important role in forelimb motor control and locomotion. Histologically it is subdivided into two subpopulations, the parvocellular RN (pRN) located in the diencephalon and the magnocellular RN (mRN) in the mesencephalon. The RN integrates signals from motor cortex and cerebellum and projects to spinal cord interneurons and motor neurons through the rubrospinal tract (RST). Pou4f1 is a transcription factor highly expressed in this nucleus that has been related to its specification. Here we profoundly analyzed consequences of Pou4f1 loss-of-function in development, maturation and axonal projection of the RN. Surprisingly, RN neurons are specified and maintained in the mutant, no cell death was detected. Nevertheless, the nucleus appeared disorganized with a strong delay in radial migration and with a wider neuronal distribution; the neurons did not form a compacted population as they do in controls, Robo1 and Slit2 were miss-expressed. Cplx1 and Npas1, expressed in the RN, are transcription factors involved in neurotransmitter release, neuronal maturation and motor function processes among others. In our mutant mice, both transcription factors are lost, suggesting an abnormal maturation of the RN. The resulting altered nucleus occupied a wider territory. Finally, we examined RST development and found that the RN neurons were able to project to the spinal cord but their axons appeared defasciculated. These data suggest that Pou4f1 is necessary for the maturation of RN neurons but not for their specification and maintenance. PMID:25698939

  11. Ketoconazole increases fingolimod blood levels in a drug interaction via CYP4F2 inhibition.

    PubMed

    Kovarik, John M; Dole, Kiran; Riviere, Gilles-Jacques; Pommier, Francoise; Maton, Steve; Jin, Yi; Lasseter, Kenneth C; Schmouder, Robert L

    2009-02-01

    The sphingosine-1-phosphate receptor modulator fingolimod is predominantly hydroxylated by cytochrome CYP4F2. In vitro experiments showed that ketoconazole significantly inhibited the oxidative metabolism of fingolimod by human liver microsomes and by recombinant CYP4F2. The authors used ketoconazole as a putative CYP4F2 inhibitor to quantify its influence on fingolimod pharmacokinetics in healthy subjects. In a 2-period, single-sequence, crossover study, 22 healthy subjects received a single 5-mg dose of fingolimod in period 1. In period 2, subjects received ketoconazole 200 mg twice daily for 9 days and a single 5-mg dose of fingolimod coadministered on the 4th day of ketoconazole treatment. Ketoconazole did not affect fingolimod t(max) or half-life, but there was a weak average increase in C(max) of 1.22-fold (90% confidence interval, 1.15-1.30). The AUC over the 5 days of ketoconazole coadministration increased 1.40-fold (1.31-1.50), and the full AUC to infinity increased 1.71-fold (1.53-1.91). The AUC of the active metabolite fingolimod-phosphate was increased to a similar extent by 1.67-fold (1.50-1.85). Ketoconazole predose plasma levels were not altered by fingolimod. The magnitude of this interaction suggests that a proactive dose reduction of fingolimod is not necessary when adding ketoconazole to a fingolimod regimen. The clinician, however, should be aware of this interaction and bear in mind the possibility of a fingolimod dose reduction based on clinical monitoring. PMID:19118083

  12. Applications Performance on NAS Intel Paragon XP/S - 15#

    NASA Technical Reports Server (NTRS)

    Saini, Subhash; Simon, Horst D.; Copper, D. M. (Technical Monitor)

    1994-01-01

    The Numerical Aerodynamic Simulation (NAS) Systems Division received an Intel Touchstone Sigma prototype model Paragon XP/S- 15 in February, 1993. The i860 XP microprocessor with an integrated floating point unit and operating in dual -instruction mode gives peak performance of 75 million floating point operations (NIFLOPS) per second for 64 bit floating point arithmetic. It is used in the Paragon XP/S-15 which has been installed at NAS, NASA Ames Research Center. The NAS Paragon has 208 nodes and its peak performance is 15.6 GFLOPS. Here, we will report on early experience using the Paragon XP/S- 15. We have tested its performance using both kernels and applications of interest to NAS. We have measured the performance of BLAS 1, 2 and 3 both assembly-coded and Fortran coded on NAS Paragon XP/S- 15. Furthermore, we have investigated the performance of a single node one-dimensional FFT, a distributed two-dimensional FFT and a distributed three-dimensional FFT Finally, we measured the performance of NAS Parallel Benchmarks (NPB) on the Paragon and compare it with the performance obtained on other highly parallel machines, such as CM-5, CRAY T3D, IBM SP I, etc. In particular, we investigated the following issues, which can strongly affect the performance of the Paragon: a. Impact of the operating system: Intel currently uses as a default an operating system OSF/1 AD from the Open Software Foundation. The paging of Open Software Foundation (OSF) server at 22 MB to make more memory available for the application degrades the performance. We found that when the limit of 26 NIB per node out of 32 MB available is reached, the application is paged out of main memory using virtual memory. When the application starts paging, the performance is considerably reduced. We found that dynamic memory allocation can help applications performance under certain circumstances. b. Impact of data cache on the i860/XP: We measured the performance of the BLAS both assembly coded and Fortran

  13. XPS investigation of DNA binding to zirconium-phosphonate surfaces.

    PubMed

    Lane, Sarah M; Monot, Julien; Petit, Marc; Bujoli, Bruno; Talham, Daniel R

    2007-07-01

    The surface coverage of phosphorylated oligonucleotides immobilized on a zirconium-phosphonate surface was analyzed using X-ray photoelectron spectroscopy (XPS). By quantifying the intensity of the N 1s signal originating from the oligonucleotide and the Zr 3d peak from the metal-phosphonate surface, the surface coverage of the oligonucleotide could be calculated with a modified substrate-overlayer model. We found relatively low surface coverages indicating that once covalently bound via the terminal phosphate the polymer chain further physisorbs to the surface limiting the adsorption of additional molecules. PMID:17275268

  14. The application of XPS to the study of MIC

    SciTech Connect

    Kearns, J.R. . Technical Center); Clayton, C.R.; Halada, G.P. . Dept. of Materials Science); Gillow, J.B.; Francis, A.J. )

    1992-01-01

    The biotic and abiotic factors that contribute to Microbiologically Influenced Corrosion (MIC) involve the transformation of chemical species at a metal surface. X-ray Photoelectron Spectroscopy (XPS) is utilized in conjunction with conventional microbiological and Quantitative Chemical Analytical techniques to better understand the effect of environmental conditions on microbial behavior as well as the ability of bacteria to alter local environmental conditions. Specifically, the interaction of Fe, Cr, Ni, Mo ions with Desulfovibrio sp. under anoxic conditions were studied. This is the first phase of a systematic study of microbial activity and the effects of alloy elements and thermo-mechanical treatments on the MIC resistance of stainless steels.

  15. XANES and XPS studies of the reduction of ammonium paramolybdate

    SciTech Connect

    Halada, G.P.; Clayton, C.R.; Isaacs, H.S.; Davenport, A.J.

    1991-12-31

    in situ glancing-angle x-ray reflectivity experiments were performed on electrochemical reduction products formed in a dilute paramolybdate solution on a platinum electrode. These data were compared with x-ray photoelectron spectra which showed formation of simple molybdate, pentavalent and tetravalent species at increasingly negative potentials. X-ray absorption data demonstrated changes in edge position, pre-edge structure and edge height corresponding to reduction and subsequent growth of the reduction product film at a number of the potentials examined with XPS.

  16. XANES and XPS studies of the reduction of ammonium paramolybdate

    SciTech Connect

    Halada, G.P.; Clayton, C.R. . Dept. of Materials Science and Engineering); Isaacs, H.S.; Davenport, A.J. )

    1991-01-01

    in situ glancing-angle x-ray reflectivity experiments were performed on electrochemical reduction products formed in a dilute paramolybdate solution on a platinum electrode. These data were compared with x-ray photoelectron spectra which showed formation of simple molybdate, pentavalent and tetravalent species at increasingly negative potentials. X-ray absorption data demonstrated changes in edge position, pre-edge structure and edge height corresponding to reduction and subsequent growth of the reduction product film at a number of the potentials examined with XPS.

  17. Simultaneous Use Of Zr And Mg Anodes In XPS

    NASA Technical Reports Server (NTRS)

    Allgeyer, D. F.; Pratz, E. H.

    1996-01-01

    Improved x-ray source for x-ray photoelectron spectroscopy (XPS) contains both zirconium anode with beryllium window and magnesium anode with aluminum window. Previously unresolvable peaks of electron-energy spectrum become resolvable. Developed specifically for use in analyzing distributions of chemical constituents in surface layers of specimens of 2219 aluminum alloy and in determining the depths of surface oxide layers and relative proportions of aluminum and oxide in layers. Also used to study chemical constituents of surface layers in other material systems - for example, thin oxide films on silicon-based semiconductor devices, oxide films on alloys, and surface layers affecting adhesion of paints or bonding materials.

  18. Tunable interplay between 3d and 4f electrons in Co-doped iron pnictides

    NASA Astrophysics Data System (ADS)

    Shang, T.; Yang, L.; Chen, Y.; Cornell, N.; Ronning, F.; Zhang, J. L.; Jiao, L.; Chen, Y. H.; Chen, J.; Howard, A.; Dai, J.; Thompson, J. D.; Zakhidov, A.; Salamon, M. B.; Yuan, H. Q.

    2013-02-01

    We study the interplay of 3d and 4f electrons in the iron pnictides CeFe1-xCoxAsO and GdFe1-yCoyAsO, which correspond to two very different cases of 4f-magnetic moment. Both CeFeAsO and GdFeAsO undergo a spin-density-wave (SDW) transition associated with Fe 3d electrons at high temperatures, which is rapidly suppressed by Fe/Co substitution. Superconductivity appears in a narrow doping range: 0.054f electrons form an antiferromagnetic (AFM) order at low temperatures over the entire doping range and Co 3d electrons are ferromagnetically ordered on the Co-rich side; the Curie temperature reaches TCCo≈ 75 K at x=1 and y=1. In the Ce compounds, the Néel temperature TNCe increases upon suppressing the SDW transition of Fe and then remains nearly unchanged with further increasing Co concentration up to x≃0.8 (TNCe≈ 4 K). Furthermore, evidence of Co-induced polarization on Ce moments is observed on the Co-rich side. In the Gd compounds, the two magnetic species of Gd and Co are coupled antiferromagnetically to give rise to ferrimagnetic behavior in the magnetic susceptibility on the Co-rich side. For 0.7≤y<1.0, the system undergoes a possible magnetic reorientation below the Néel temperature of Gd (TNGd). Our results suggest that the effects of both electron hybridizations and magnetic exchange coupling between the 3d-4f electrons give rise to a rich phase diagram in the rare-earth iron pnictides.

  19. XeCl laser pumped iodine laser using t-C4F9I

    NASA Technical Reports Server (NTRS)

    Hwang, In Heon; Han, Kwang S.

    1989-01-01

    An iodine photodissociation laser using t-C4F9I as the active material was pumped by an XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodide pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency and low threshold pump power achieved in this experiment are attributable to the high absorption cross section at the pump laser wavelength (308 nm) of the iodide used.

  20. XeCl laser pumped iodine laser using t-C4F9I

    NASA Technical Reports Server (NTRS)

    Hwang, In Heon; Han, Kwang S.; Lee, Ja H.

    1989-01-01

    An iodine photodissociation laser using t-C4F9I as the active material was pumped by a XeCl laser. An iodine laser output energy of 3 mJ with pulse duration of 25 ns was obtained when the pumping pulse energy was 80 mJ, the iodine pressure was 70 torr, and the reflectance of the output mirror was 85 percent. The high pumping efficiency and low threshold pump power achieved in this experiment are attributable to the high absorption cross section at the pump laser wavelength (308 nm) of the iodide used.

  1. Field-free molecular alignment detection by 4 f coherent imaging

    NASA Astrophysics Data System (ADS)

    Houzet, J.; Billard, F.; Hertz, E.; Chateau, D.; Chaussard, F.; Lavorel, B.; Faucher, O.

    2012-09-01

    Time-resolved detection of field-free molecular alignment is investigated by phase contrast. The technique based on a 4 f imager operating as an inverted Zernike spatial filter makes it possible to discriminate between positive and negative molecular alignment revivals produced in a linear molecule. The measurements are performed in a way that minimizes the contamination of the signal by the plasma generated during the aligning pulse. The observations are supported by a semi-analytical model, from which the degree of alignment produced at the beam focus is estimated.

  2. 4-[F-18]fluoroproline: A potential tracer for collagen synthesis. Radiosynthesis and biological evaluation

    SciTech Connect

    Hamacher, K.; Herz, M.; Truckenbrodt, R.

    1996-05-01

    Proline is an important constituent of the structural protein collagen. It has been shown that its fluorinated analogs (2S,4S)- and particularly (2S,4R)-4-fluoroproline are also incorporated into collagen (Gottlieb et al., Biochemistry (1965), 4: 2507). 4-[F-18]fluoroproline is therefore a potential probe for studying abnormal collagen synthesis e. g. in tumors, lung fibrosis and liver cirrhosis. We have evaluated the two diastereomeric forms using a transplantable osteosarcoma in mice as an in vivo model for elevated collagen synthesis, and a MCF 7 mamma carcinoma cell line for monolayer incubation studies.

  3. Synthesis Dependent Core Level Binding Energy Shift in the Oxidation State of Platinum Coated on Ceria–Titania and its Effect on Catalytic Decomposition of Methanol

    SciTech Connect

    Karakoti, A. S.; King, Jessica; Vincent, Abhilash; Seal, Sudipta

    2010-11-20

    Synergistic interaction of catalyst and support has attracted the interest of the catalytic community for several decades. The decomposition/oxidation of alcohols for the production of hydrogen as a source of fuel requires such support catalyst interaction. Recent studies have suggested the active role of oxide based supports on the catalytic ability of noble metals such as gold, platinum and palladium. Herein, we report the effect of synthesis technique on the catalytic activity of platinum coated on mixed ceria-titania support system. Wet impregnation technique followed by calcination was compared with the chemical reduction of platinum during the coating over oxide support. Methanol decomposition studied using an in-house built catalytic reactor coupled to a mass spectrometer showed that catalyst prepared by thermal reduction of platinum demonstrated better catalytic ability than the catalyst prepared by chemical reduction of platinum. Transmission electron microscopy revealed that the size of both platinum and ceria-titania particles remained unchanged, while the X-ray photoelectron spectroscopy (XPS) revealed that the oxidation state of platinum was modified by different coating procedures. A shift in the core level binding energy of the Pt 4f towards lower binding energy was observed with chemical reduction. Based on the XPS data it was found that platinum (on ceria-titania supports) in mixed oxidation state outperformed the Pt in reduced metallic state. Results from catalysis and in situ Fourier transform infra red spectroscopy are presented and discussed.

  4. XPS study of. beta. -carbon hydrogenation on Nickel(111) surface

    SciTech Connect

    Dost, A.A.; Dhanak, V.R.; Buckingham, S.

    1984-09-01

    The methanation reaction has been studied extensively using conventional catalysis and modern surface science techniques. It is now well established that the mechanism of this reaction involves the dissociative adsorption of carbon monoxide to produce highly reactive carbidic carbon (..cap alpha..-carbon) which is subsequently hydrogenated to produce methane. Under conditions of low hydrogen concentration, and high temperature, however, the reactive ..cap alpha..-C can be transformed into relatively less-reactive graphitic carbon (..beta..-carbon). The nature of ..beta..-carbon has been suggested to be graphitic as characterized by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and temperature programmed surface reaction (TPSR) in hydrogen. Using XPS, it is demonstrated directly that conversion of ..beta..-carbon to ..cap alpha..-carbon does occur at ..beta..-carbon hydrogenation temperature and that the rate-determining step in the hydrogenation of ..beta..-carbon may be the detachment of carbon atoms from ..beta..-carbon islands. 19 references, 6 figures.

  5. XPS, AES and SEM analysis of recent dental implants.

    PubMed

    Kang, Byung-Soo; Sul, Young-Taeg; Oh, Se-Jung; Lee, Hyun-Ju; Albrektsson, Tomas

    2009-07-01

    Today, surface chemistry modifications of titanium implants have become a development strategy for dental implants. The present study investigated the chemistry and morphology of commercially available dental implants (Nobel biocare TiUnite, Astra AB OsseoSpeed, 3i Osseotite, ITI-SLA). X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy were employed for the analysis of surface chemistry. The morphology was investigated by scanning electron microscopy. The present study demonstrated the major differences of surface properties, mainly dependent on the surface treatment used. The blasting and acid etching technique for the OsseoSpeed, Osseotite and SLA surfaces generally showed mainly TiO(2), but a varying surface morphology. In contrast, the electrochemical oxidation process for TiUnite implants not only produces microporous surface (pore size: 0.5-3.0microm), but also changes surface chemistry due to incorporation of anions of the used electrolyte. As a result, TiUnite implants contain more than 7at.% of P in oxide layer and higher amounts of hydroxides compared to the other implants in XPS analysis. F in OsseoSpeed implants was detected at 0.3% before as well as after sputter cleaning. PMID:19261554

  6. Data warehousing features in Informix OnLine XPS

    SciTech Connect

    Sundaresan, P.

    1996-12-31

    The Data Warehousing application domain is an important area of focus for Informix`s OnLine XPS massively parallel server. Fast query processing is a central requirement in this domain. Use of indexes has traditionally been an important query processing technique, helping to reduce response times and increase throughput. The data warehousing environment, characterized by its load-query-refresh mode of operation, offers even greater scope for use of indexes. This talk will describe three new indexing related features in OnLine XPS which together provide significant performance benefits in a wide variety of situations. Bitmap indexes, along with multi-index scans, provide orders-of-magnitude improvement for queries typified by the Set Query Benchmark. Pushdown Semi-joins combine the benefits of multi-index scans with the scalability of hash joins to efficiently process star-joins. Finally, Generalized-key indexes expand the notion of what can be an index key and provide the ability to store various pre-computed results in an index. Optimizer extensions allow these features to be used in a mix-n-match fashion, thus maximizing the benefits of these features while minimizing the need for user level directives.

  7. Azide interaction with 4f and 5f ions in aqueous solutions. I. Trivalent ions

    SciTech Connect

    Musikas, C.; Cuillerdier, C.; Livet, J.; Forchioni, A.; Chachaty, C.

    1983-08-31

    Solvent extraction and UV, Raman, and NMR spectroscopic studies were carried out on trivalent actinide and lanthanide aqueous azido complexes. Unlike trivalent d transition ions (..beta../sub 11/ approx. = 10/sup 5/) 5f and 4f aqueous azido complexes are weak (..beta../sub 11/ approx. = 2.5 for neodymium azide complexes (Nd(N/sub 3/)/sup 2 +/)), but the trivalent actinides exhibit formation constants 1 order of magnitude higher than the lanthanides. All the spectroscopic methods indicate that we are dealing with inner-sphere complexes and actinide-lanthanide differences must be attributed to higher covalent contributions in the 5f azides. /sup 15/N NMR combined with /sup 1/H NMR served to investigate the azide binding properties. With the trivalent 5f and 4f ions the binding occurs by one of the terminal nitrogen atoms. The M-N bond distance is close to 2.75 A. The lanthanide(III)-(linear azide) moieties are bent with a bond angle close to 135/sup 0/, unlike the homologous linear thiocyanate complexes. 7 figures, 4 tables.

  8. Sub-molecular modulation of a 4f driven Kondo resonance by surface-induced asymmetry

    NASA Astrophysics Data System (ADS)

    Warner, Ben; El Hallak, Fadi; Atodiresei, Nicolae; Seibt, Philipp; Pruser, Henning; Caciuc, Vasile; Waters, Michael; Fisher, Andrew J.; Blugel, Stefan; van Slageren, Joris; Hirjibehedin, Cyrus F.

    Coupling between a magnetic impurity and an external bath can give rise to many-body quantum phenomena, including Kondo and Hund's Impurity states in metals, and Yu-Shiba-Rusinov states in superconductors. While advances have been made in probing the magnetic properties of d-shell impurities on surfaces, the confinement of f orbitals makes them much more difficult to access directly. Here we show that a 4f driven Kondo resonance can be modulated spatially by asymmetric coupling between a metallic surface and a molecule containing a 4f-like moment. Strong hybridisation of dysprosium double-decker phthalocyanine (DyPc2) with Cu(001) induces Kondo screening of the central magnetic moment. Misalignment between the symmetry axes of the molecule and the surface induces asymmetry in the molecule's electronic structure, spatially mediating electronic access to the magnetic moment through the Kondo resonance. This work demonstrates the important role that molecular ligands play in mediating electronic and magnetic coupling and in accessing many-body quantum states.

  9. Experimental and theoretical investigations of four 3d-4f butterfly single-molecule magnets.

    PubMed

    Zou, Hua-Hong; Sheng, Liang-Bing; Liang, Fu-Pei; Chen, Zi-Lu; Zhang, Yi-Quan

    2015-11-14

    The syntheses, structures, and characterization of four 3d-4f butterfly clusters are described. With different polyhydroxy Schiff-base ligands 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H4L1) and 2-(2,3-dihydroxpropyliminomethyl)-6-methoxyphenol (H3L2), three heterotetranuclear NiLn complexes (NiDy-L1 (1), NiTb-L2 (2), NiDy-L2 (3)) and one heterohexanuclear CoDy complex (4) were obtained. The three heterotetranuclear NiLn complexes display a central planar butterfly topology. The heterohexanuclear complex was built from butterfly CoDy clusters and two Dy(III) ions by the bridging of pivalate. The vertices of the body positions of the butterfly are occupied by transition metal ions in all four complexes. Magnetic analyses indicate that the complexes exhibit typical single-molecule magnet behaviour with anisotropy barriers of 33.7 cm(-1), 60.3 cm(-1), 39.6 cm(-1), and 18.4 cm(-1) for 1-4, respectively. Ab initio calculations were performed on these complexes, and the low lying electronic structure of each Ln(III) (Ln = Dy, Tb) ion and the magnetic interactions were determined. It was found that the two Ln ions may have much more contribution to the total relaxation barrier through the stronger 3d-4f exchange couplings compared to weak Ln-Ln interactions. PMID:26443303

  10. Sequential Synthesis of 3d-3d'-4f Heterometallic Heptanuclear Clusters in between Lacunary Polyoxometalates.

    PubMed

    Sato, Rinta; Suzuki, Kosuke; Minato, Takuo; Yamaguchi, Kazuya; Mizuno, Noritaka

    2016-03-01

    In this work, we have successfully created several unprecedented discrete 3d-3d'-4f heterotrimetallic clusters in between lacunary polyoxometalates (POMs). By the three-step sequential introduction of metal cations into a trivacant lacunary POM TBA4H6[A-α-SiW9O34] (TBA = tetra-n-butylammonium) in organic media, five kinds of sandwich-type POMs with double-diamond-shaped 3d-3d'-4f heptanuclear clusters (IIIFeM4Ln2, TBAnHm[FeM4{Ln(L)2}2O2(A-α-SiW9O34)2], M = Mn(3+), Cu(2+); Ln = Gd(3+), Dy(3+), Lu(3+); L = acac (acetylacetonate), hfac (hexafluoroacetylacetonate)) were successfully synthesized for the first time. By introduction of two [Ln(L)2](+) units on the ends of pentanuclear clusters [FeMn4O18(OH)2](23-) and [FeCu4O18(OH)2](27-), the magnetic interactions between Mn(3+)-Mn(3+) and Cu(2+)-Cu(2+) could be modulated. Among a series of the heterometallic heptanuclear compounds, IIIFeMn4Lu2 exhibited the slow magnetic relaxation characteristic for a single-molecule magnet under the zero applied magnetic fields. PMID:26914662

  11. Monolacunary Keggin polyoxometalates connected to ten 4d or 4f metal atoms.

    PubMed

    Pang, Haijun; Gómez-García, Carlos J; Peng, Jun; Ma, Huiyuan; Zhang, Chunjing; Wu, Qingyin

    2013-12-21

    The rational self-assembly of mono-lacunary Keggin clusters with 4d and 4f metal salts via a conventional method has yielded two novel polyoxometalate-based 4d-4f heterometallic compounds containing lacunary Keggin anions connected to ten metal atoms: {[Ag{Ag2(H2O)4}{Ln(H2O)6}2H ⊂ {SiW11Ln(H2O)4O39}2]·nH2O (Ln = Ce and n = 7 for 1, Ln = Pr and n = 3 for 2). Their structures were determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. A structural feature in 1 and 2 is that each [SiW11O39](8-) cluster (SiW11) is connected to ten metals (five Ag(+) and five Ln(3+) cations), representing the highest number of connected metal atoms to any mono-lacunary Keggin anion to date. This large connectivity leads to a structure with a purely inorganic 3D framework with two kinds of channels along the [100] and [010] directions. The magnetic properties of both compounds show the expected magnetic moments (0.8 and 1.6 amu K mol(-1) per Ce(3+) and Pr(3+) ion, respectively) and confirm the presence of isolated Ce(3+) and Pr(3+) ions. PMID:24067933

  12. Lattice dynamics and elastic properties of the 4f electron system: CeN

    NASA Astrophysics Data System (ADS)

    Kanchana, V.; Vaitheeswaran, G.; Zhang, Xinxin; Ma, Yanming; Svane, A.; Eriksson, O.

    2011-11-01

    The electronic structure, structural stability, and lattice dynamics of cerium mononitride are investigated using ab initio density-functional methods involving an effective potential derived from the generalized gradient approximation and without special treatment for the 4f states. The 4f states are hence allowed to hop from site to site, without an on-site Hubbard U, and contribute to the bonding, in a picture often referred to as itinerant. It is argued that this picture is appropriate for CeN at low temperatures, while the anomalous thermal expansion observed at elevated temperatures indicates entropy-driven localization of the Ce f electrons, similar to the behavior of elemental cerium. The elastic constants are predicted from the total energy variation of strained crystals and are found to be large, typical for nitrides. The phonon dispersions are calculated showing no soft modes, and the Grüneisen parameter behaves smoothly. The electronic structure is also calculated using the quasiparticle self-consistent GW approximation (where G denotes the Green's function and W denotes the screened interaction). The Fermi surface of CeN is dominated by large egg-shaped electron sheets centered on the X points, which stem from the p-f mixing around the X point. In contrast, assuming localized f electrons leads to a semimetallic picture with small band overlaps around X.

  13. Optical alignment of pixelated 4f optical system using multiplexed filter.

    PubMed

    Manivannan, N; Neil, M A A; Balachandran, W

    2013-11-10

    Novel optical alignment techniques to perform precise alignment of a typical pixelated 4f optical system are presented in this paper. These techniques use optical multiplexed matched filters, which were designed using a simple, efficient iterative optimization algorithm, known as direct binary search. Three alignment challenges are identified: positioning, focusing, and magnification. The first two alignments were performed using the optical multiplexed matched filtering technique, and the last one was performed using a new optical arrangement. Experimental results of the new alignment techniques and a simple optical pattern recognition problem to demonstrate the benefits of the new alignment techniques are also presented. Two pixelated, electrically addressed spatial light modulators (128 × 128 pixels and one pixel width is 80 μm) were used to represent the input and filter planes. The results clearly show that the new alignment techniques allow the 4f system to be aligned to a precision of 80 μm in the x-y direction and 0.716 mm in the z direction. PMID:24216742

  14. XPS investigations of ruthenium deposited onto representative inner surfaces of nuclear reactor containment buildings

    NASA Astrophysics Data System (ADS)

    Mun, C.; Ehrhardt, J. J.; Lambert, J.; Madic, C.

    2007-07-01

    In the case of a hypothetical severe accident in a nuclear power plant, interactions of gaseous RuO 4 with reactor containment building surfaces (stainless steel and epoxy paint) could possibly lead to a black Ru-containing deposit on these surfaces. Some scenarios include the possibility of formation of highly radiotoxic RuO 4(g) by the interactions of these deposits with the oxidizing medium induced by air radiolysis, in the reactor containment building, and consequently dispersion of this species. Therefore, the accurate determination of the chemical nature of ruthenium in the deposits is of the high importance for safety studies. An experiment was designed to model the interactions of RuO 4(g) with samples of stainless steel and of steel covered with epoxy paint. Then, these deposits have been carefully characterised by scanning electron microscopy (SEM/EDS), electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). The analysis by XPS of Ru deposits formed by interaction of RuO 4(g), revealed that the ruthenium is likely to be in the IV oxidation state, as the shapes of the Ru 3d core levels are very similar with those observed on the RuO 2· xH 2O reference powder sample. The analysis of O 1s peaks indicates a large component attributed to the hydroxyl functional groups. From these results, it was concluded that Ru was present on the surface of the deposits as an oxyhydroxide of Ru(IV). It has also to be pointed out that the presence of "pure" RuO 2, or of a thin layer of RuO 3 or Ru 2O 5, coming from the decomposition of RuO 4 on the surface of samples of stainless steel and epoxy paint, could be ruled out. These findings will be used for further investigations of the possible revolatilisation phenomena induced by ozone.

  15. Heterometallic 3d-4f single-molecule magnets: ligand and metal ion influences on the magnetic relaxation.

    PubMed

    Langley, Stuart K; Le, Crystal; Ungur, Liviu; Moubaraki, Boujemaa; Abrahams, Brendan F; Chibotaru, Liviu F; Murray, Keith S

    2015-04-01

    Six tetranuclear 3d–4f single-molecule magnet (SMM) complexes formed using N-n-butyldiethanolamine and N-methyldiethanolamine in conjunction with ortho- and para-substituted benzoic acid and hexafluoroacetoacetone ligands yield two families, both having a butterfly metallic core. The first consists of four complexes of type {Co2(III)Dy2(III)} and {Co2(III)Co(II)Dy(III)} using N-n-butyldiethanolamine with variation of the carboxylate ligand. The anisotropy barriers are 80 cm–1, (77 and 96 cm–1—two relaxation processes occur), 117 and 88 cm–1, respectively, each following a relaxation mechanism from a single DyIII ion. The second family consists of a {Co2(III)Dy2(III)} and a {Cr2(III)Dy2(III)} complex, from the ligand combination of N-methyldiethanolamine and hexafluoroacetylacetone. Both show SMM behavior, the Co(III) example displaying an anisotropy barrier of 23 cm–1. The Cr(III) complex displays a barrier of 28 cm–1, with longer relaxation times and open hysteresis loops, the latter of which is not seen in the Co(III) case. This is a consequence of strong Dy(III)–Cr(III) magnetic interactions, with the relaxation arising from the electronic structure of the whole complex and not from a single DyIII ion. The results suggest that the presence of strong exchange interactions lead to significantly longer relaxation times than in isostructural complexes where the exchange is weak. The study also suggests that electron-withdrawing groups on both bridging (carboxylate) and terminal (β-diketonate) ligands enhance the anisotropy barrier. PMID:25796958

  16. Influence of the CYP4F2 polymorphism on the risk of hemorrhagic complications in coumarin-treated patients

    PubMed Central

    Chen, Peng; Sun, Ye-Qi; Yang, Guo-Ping; Li, Rong; Pan, Jie; Zhou, Yu-Sheng

    2016-01-01

    Objectives: To evaluate the impact of the CYP4F2 polymorphism on bleeding complications and over-anticoagulation due to coumarin. Methods: A comprehensive literature search was performed to look for eligible studies published prior to February 2015 in EMBASE and PubMed. References were strictly identified by inclusion and exclusion criteria, and authors of primary studies were consulted for additional information and data. Revman 5.3 software was used to analyze the impact of the CYP4F2 polymorphism on hemorrhagic complications and over-anticoagulation events (international normalized ratio >4). Results: Eight studies involving 3,101 samples met the specified inclusion criteria. Compared with wild-type homozygotes (CYP4F2*1*1), carriers of the CYP4F2*3 variant had no significant effects on total bleeding events (odds ratio [OR]: 0.86; 95% confidence interval [CI]: 0.71-1.05; p=0.15), major hemorrhage complications in coumarin users (OR: 0.80; 95% CI: 0.64-1.01; p=0.06). Patients carried CYP4F2*3 also had nonsignificant associations with the risk of over-anticoagulation (relative risk [RR]: 079; 95% CI: 0.59-1.06; p=0.12). We found a lower risk in patients with homozygotes for CYP4F2*3, but there was no statistical significance (RR: 0.66; 95% CI: 0.43-1.01; p=0.05). Conclusion: This meta-analysis indicated the impact of the CYP4F2 polymorphism on bleeding complications and over-anticoagulation in coumarin-treated patients failed to reach the level of statistical significance. However, large-scale and well designed studies are necessary to determine conclusively the association between the CYP4F2 polymorphism and hemorrhage risk. PMID:27052278

  17. 3d-4f magnetic interaction with density functional theory plus u approach: local Coulomb correlation and exchange pathways.

    PubMed

    Zhang, Yachao; Yang, Yang; Jiang, Hong

    2013-12-12

    The 3d-4f exchange interaction plays an important role in many lanthanide based molecular magnetic materials such as single-molecule magnets and magnetic refrigerants. In this work, we study the 3d-4f magnetic exchange interactions in a series of Cu(II)-Gd(III) (3d(9)-4f(7)) dinuclear complexes based on the numerical atomic basis-norm-conserving pseudopotential method and density functional theory plus the Hubbard U correction approach (DFT+U). We obtain improved description of the 4f electrons by including the semicore 5s5p states in the valence part of the Gd-pseudopotential. The Hubbard U correction is employed to treat the strongly correlated Cu-3d and Gd-4f electrons, which significantly improve the agreement of the predicted exchange constants, J, with experiment, indicating the importance of accurate description of the local Coulomb correlation. The high efficiency of the DFT+U approach enables us to perform calculations with molecular crystals, which in general improve the agreement between theory and experiment, achieving a mean absolute error smaller than 2 cm(-1). In addition, through analyzing the physical effects of U, we identify two magnetic exchange pathways. One is ferromagnetic and involves an interaction between the Cu-3d, O-2p (bridge ligand), and the majority-spin Gd-5d orbitals. The other one is antiferromagnetic and involves Cu-3d, O-2p, and the empty minority-spin Gd-4f orbitals, which is suppressed by the planar Cu-O-O-Gd structure. This study demonstrates the accuracy of the DFT+U method for evaluating the 3d-4f exchange interactions, provides a better understanding of the exchange mechanism in the Cu(II)-Gd(III) complexes, and paves the way for exploiting the magnetic properties of the 3d-4f compounds containing lanthanides other than Gd. PMID:24274078

  18. Secondary electron measurement and XPS characterization of NEG coatings

    SciTech Connect

    Sharma, R. K. Sinha, Atul K. Gupta, Nidhi Nuwad, J. Jagannath, Gadkari, S. C. Singh, M. R. Gupta, S. K.

    2014-04-24

    Ternary alloy coatings of IVB and VB materials provide many of benefits over traditional material surfaces such as creation of extreme high vacuum(XHV), lower secondary electron yield(SEY), low photon desorption coefficient. XHV (pressure < 10{sup −10} mbar) is very useful to the study of surfaces of the material in as it is form, high energy particle accelerators(LHC, Photon Factories), synchrotrons (ESRF, Ellectra) etc.. Low secondary electron yield leads to very low multi-pacting utilizes to increase beam life time. In this paper preparation of the coatings and a study of secondary electron yield measurement after heating at different temperatures has been shown also results of their surface characterization based on shift in binding energy has been produced using the surface techniques XPS. Stoichiometry of the film was measured by Energy dispersive x-ray analysis (EDX)

  19. Silicon (100)/SiO2 by XPS

    SciTech Connect

    Jensen, David S.; Kanyal, Supriya S.; Madaan, Nitesh; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Linford, Matthew R.

    2013-09-25

    Silicon (100) wafers are ubiquitous in microfabrication and, accordingly, their surface characteristics are important. Herein, we report the analysis of Si (100) via X-ray photoelectron spectroscopy (XPS) using monochromatic Al K radiation. Survey scans show that the material is primarily silicon and oxygen, and the Si 2p region shows two peaks that correspond to elemental silicon and silicon dioxide. Using these peaks the thickness of the native oxide (SiO2) was estimated using the equation of Strohmeier.1 The oxygen peak is symmetric. The material shows small amounts of carbon, fluorine, and nitrogen contamination. These silicon wafers are used as the base material for subsequent growth of templated carbon nanotubes.

  20. Optical Evidence of Itinerant-Localized Crossover of 4f Electrons in Cerium Compounds

    NASA Astrophysics Data System (ADS)

    Kimura, Shin-ichi; Kwon, Yong Seung; Matsumoto, Yuji; Aoki, Haruyoshi; Sakai, Osamu

    2016-08-01

    Cerium (Ce)-based heavy-fermion materials have a characteristic double-peak structure (mid-IR peak) in the optical conductivity [σ(ω)] spectra originating from the strong conduction (c)-f electron hybridization. To clarify the behavior of the mid-IR peak at a low c-f hybridization strength, we compared the σ(ω) spectra of the isostructural antiferromagnetic and heavy-fermion Ce compounds with the calculated unoccupied density of states and the spectra obtained from the impurity Anderson model. With decreasing c-f hybridization intensity, the mid-IR peak shifts to the low-energy side owing to the renormalization of the unoccupied 4f state, but suddenly shifts to the high-energy side owing to the f-f on-site Coulomb interaction at a slight localized side from the quantum critical point (QCP). This finding gives us information on the change in the electronic structure across QCP.

  1. 5d-4f transition in new phosphate-based phosphors.

    PubMed

    Shinde, K N; Dhoble, S J

    2012-01-01

    The preparation of Ce(3+)-doped Sr(6) AlP(5) O(20) and Ba(6) AlP(5) O(20) by a combustion method is described. Formation of compounds was confirmed by X-ray diffraction (XRD) analysis. The photoluminescence (PL) emission spectra were observed at 355 nm when excited at 307 nm for the various concentrations. The PL emission spectra of phosphors showed strong Ce(3+) emission due to the 5 d → 4f transition of Ce(3+) ions. The Ce(3+) emission intensity in Sr(6) AlP(5)O(20):Ce phosphor was higher than that in Ba(6) AlP(5)O(20):Ce and it may be useful for scintillation applications. PMID:21692165

  2. Self-Assembly of Hexanuclear Clusters of 4f and 5f Elements with Cation Specificity

    SciTech Connect

    Diwu, J.; Good, Justin J.; DiStefano, Victoria H.; Albrecht-Schmitt, Thomas E.

    2011-02-10

    Six hexanuclear clusters of 4f and 5f elements were synthesized by room-temperature slow concentration experiments. Cerium(IV), thorium(IV), and plutonium(IV) each form two different hexanuclear clusters, among which the cerium and plutonium clusters are isotypic, whereas the thorium clusters show more diversity. The change in ionic radii of approximately 0.08 Å between these different metal ions tunes the cavity size so that NH{sub 4}{sup +} (1.48 Å) has the right dimensions to assemble the cerium and plutonium clusters, whereas Cs{sup +} (1.69 Å) is necessary to assemble the thorium clusters. If these cations are not used in the reactions, only amorphous material is obtained.

  3. Magnetism and superconductivity driven by identical 4f states in a heavy-fermion metal

    SciTech Connect

    Thompson, Joe E; Nair, S; Stockert, O; Witte, U; Nicklas, M; Schedler, R; Bianchi, A; Fisk, Z; Wirth, S; Steglich, K

    2009-01-01

    The apparently inimical relationship between magnetism and superconductivity has come under increasing scrutiny in a wide range of material classes, where the free energy landscape conspires to bring them in close proximity to each other. Particularly enigmatic is the case when these phases microscopically interpenetrate, though the manner in which this can be accomplished remains to be fully comprehended. Here, we present combined measurements of elastic neutron scattering, magnetotransport, and heat capacity on a prototypical heavy fermion system, in which antiferromagnetism and superconductivity are observed. Monitoring the response of these states to the presence of the other, as well as to external thermal and magnetic perturbations, points to the possibility that they emerge from different parts of the Fermi surface. Therefore, a single 4f state could be both localized and itinerant, thus accounting for the coexistence of magnetism and superconductivity.

  4. 4f metals (compounds) under High Pressure (and Temperature): f-electron Correlation Physics

    NASA Astrophysics Data System (ADS)

    Lipp, Magnus; Jenei, Zsolt; Cynn, Hyunchae; Evans, William; Physics Division Team

    The physics of 4f-electron correlation governs the behavior of the most interesting group in the periodic table, the rare-earth elements. Arguably the most celebrated example is cerium with its iso-structural (fcc) volume collapse (VC) from the γ- to the α-phase ending in a critical point. Close to the VC cerium is even auxetic since its Poisson's ratio becomes negative. Radiography tells us that both phases continue on into the melt, possibly separated by a first order transition. The presence of the f-electron can be interrogated via X-ray emission spectroscopy of the satellite intensity of the L γ radiation. Across the VC it experiences a step-like drop which could be interpreted as a discontinuous decrease of the 4f-moment or occupancy. The theoretical models (Hubbard-Mott or Kondo) explain these phenomena with the behavior of the f-electrons themselves or their spin but the contribution of the lattice-phonons also plays an important part. However, its share in the entropy change across the VC decreases with temperature. This work was performed under the auspices of the US DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The X-ray studies were performed at HPCAT (Sector 16), APS/ANL. HPCAT is supported by CIW, CDAC, UNLV and LLNL through funding from DOE-NNSA, DOE-BES and NSF. APS is supported by DOE-BES, under Contract No. DE-AC02-06CH11357.

  5. Anti-adhesive characteristics of CHF{sub 3}/O{sub 2} and C{sub 4}F{sub 8}/O{sub 2} plasma-modified silicon molds for nanoimprint lithography

    SciTech Connect

    Lee, Jaemin; Lee, Junmyung; Lee, Hyun Woo; Kwon, Kwang-Ho

    2015-09-15

    The anti-adhesive characteristics of a plasma-modified silicon mold surface for nanoimprint lithography are presented. Both CHF{sub 3}/O{sub 2} and C{sub 4}F{sub 8}/O{sub 2} plasma were used to form an anti-adhesive layer on silicon mold surfaces. The gas mixing ratios of CHF{sub 3}/O{sub 2} and C{sub 4}F{sub 8}/O{sub 2} were experimentally changed between 0% and 80% to optimize the plasma conditions to obtain a low surface energy of the silicon mold. The plasma characteristics were examined by optical emission spectroscopy (OES). In order to investigate the changes in surface energy and surface chemistry of the anti-adhesive layer during repeated demolding cycles, contact angle measurements and X-ray photoelectron spectroscopy (XPS) were performed on the plasma-modified silicon mold surface. Simultaneously, the surface morphology of the demolded resists was evaluated by field-emission scanning electron microscope (FE-SEM) in order to examine the effect of the anti-adhesive layers on the duplicated patterns of the resists. It was observed that the anti-adhesive layer formed by CHF{sub 3}/O{sub 2} plasma treatment was worn out more easily during repeated demolding cycles than the film formed by C{sub 4}F{sub 8}/O{sub 2} plasma treatment, because CHF{sub 3}/O{sub 2} gas plasma formed a thinner plasma-polymerized film over the same plasma treatment time.

  6. XPS study on La0.67Ca0.33Mn1-xCoxO3 compounds

    NASA Astrophysics Data System (ADS)

    Dudric, R.; Vladescu, A.; Rednic, V.; Neumann, M.; Deac, I. G.; Tetean, R.

    2014-09-01

    The electronic structure of the polycrystalline La0.67Ca0.33Mn1-xCoxO3 compounds with x = 0.5, 0.6, 0.7, 0.8, 0.9 and 1 has been investigated by X-ray photoelectron spectroscopy (XPS). The valence band and the transition metal core level spectra were analyzed. Several contributions from the Mn 3d, Co 3d and of extensively hybridized Mn3d-O2p and Co3d-O2p states were found in the spectral region between 2 eV and 5 eV. The core level spectra show the presence of Co4+ and Co2+ states.

  7. A MoS2 coating strategy to improve the comprehensive electrochemical performance of LiVPO4F

    NASA Astrophysics Data System (ADS)

    Liu, Zhaomeng; Peng, Wenjie; Shih, Kaimin; Wang, Jiexi; Wang, Zhixing; Guo, Huajun; Yan, Guochun; Li, Xinhai; Song, Liubin

    2016-05-01

    To improve the electrochemical performance of LiVPO4F at room and elevated temperature focusing on the stability of LiVPO4F electrode/electrolyte interface, for the first time, MoS2 nanosheets are introduced to modify LiVPO4F/C composites. The coating of MoS2 layers on the surface of LiVPO4F/C nanoparticles is realized via a solution method followed by low-temperature calcination. Morphological observations present that the MoS2 sheets are homogeneously wrapped around the LiVPO4F/C particles. When employed as cathode materials for lithium ion batteries, the MoS2-modified LiVPO4F/C composites exhibit superior high-rate capability and greatly improved cycle ability compared to bare one, and the sample coated with 1.75 wt% MoS2 (2M-LVPF) delivers the best electrochemical performance. In particular, it maintains the capacity retention of 91.7% in 100 cycles at 2.0C and delivers a reversible specific capacity of 112 mAh g-1 at a high rate of 8.0C under room temperature. More importantly, it shows greatly improved cycling stability at elevated temperature (55 °C), maintaining 88.1% of its initial capacity at 0.5C after 50 cycles. The reasons for such improvement lie in the MoS2 coating layer acting as a physical barrier between electrode and electrolyte, as well as electronic/ionic conducting framework for LiVPO4F particles.

  8. Use of the 4F Roesch Inferior Mesenteric Catheter in Embolization Procedures in the Pelvis: A Review of 300 Cases

    SciTech Connect

    Kroencke, Thomas J. Kluner, Claudia; Hamm, Bernd; Gauruder-Burmester, Annett

    2007-04-15

    The aim of this study is to evaluate the use of a 4F Roesch inferior mesenteric (RIM) catheter for pelvic embolization procedures. Between October 2000 and January 2006, 364 patients (357 female, 7 male; age: 23-67 years) underwent embolization of various pathologies [uterine fibroids (n = 324), pure adenomyosis of the uterus (n = 19), postpartum hemorrhage (n =1), traumatic or postoperative hemorrhage (n = 9), bleeding related to cervical cancer (n =7), AV malformation of the uterus (n = 2) and high-flow priapism (n = 2)] at a single institution. In all cases, bilateral catheterization was primarily attempted with the use of a 4F hook-shaped braided endhole catheter (Roesch-Inferior-Mesenteric, RIM-Catheter, Cordis, Miami, FL). Frequency of initial failure to catheterize the vascular territory of interest and carry out the embolization were recorded and the types of difficulty encountered were noted. Catherization of the main stem of the vessel territory of interest with the use of a unilateral femoral approach and the 4F RIM catherer was successful in 334/364 (91.8%) the embolization cases. Bilateral catheterization of the internal iliac arteries using a single common femoral artery access and the 4F RIM catheter was achieved in 322/364 (88.5%) patients. In 12/364 (3.3%) patients, a contralateral puncture was performed and the same 4F catheter was used. In 28/364 (7.7%) cases the 4F RIM catheter was exchanged for a catheter with a cobra-shaped or sidewinder configuration. The 4F RIM catheter is a simple and valuable alternative to catheters and techniques commonly employed for pelvic artery embolization.

  9. Altered Leukotriene B4 metabolism in CYP4F18-deficient mice does not impact inflammation following renal ischemia

    PubMed Central

    Winslow, Valeria; Vaivoda, Rachel; Vasilyev, Aleksandr; Dombkowski, David; Douaidy, Karim; Stark, Christopher; Drake, Justin; Guilliams, Evin; Choudhary, Dharamainder; Preffer, Frederic; Stoilov, Ivaylo; Christmas, Peter

    2014-01-01

    Inflammatory responses to infection and injury must be restrained and negatively regulated to minimize damage to host tissue. One proposed mechanism involves enzymatic inactivation of the pro-inflammatory mediator leukotriene B4, but it is difficult to dissect the roles of various metabolic enzymes and pathways. A primary candidate for a regulatory pathway is omega oxidation of leukotriene B4 in neutrophils, presumptively by CYP4F3A in humans and CYP4F18 in mice. This pathway generates ω, ω-1, and ω-2 hydroxylated products of leukotriene B4, depending on species. We created mouse models targeting exons 8 and 9 of the Cyp4f18 allele that allows both conventional and conditional knockout of Cyp4f18. Neutrophils from wild-type mice convert leukotriene B4 to 19-hydroxy leukotriene B4, and to a lesser extent 18-hydroxy leukotriene B4, whereas these products were not detected in neutrophils from conventional Cyp4f18 knockouts. A mouse model of renal ischemia-reperfusion injury was used to investigate the consequences of loss of CYP4F18 in vivo. There were no significant changes in infiltration of neutrophils and other leukocytes into kidney tissue as determined by flow cytometry and immunohistochemistry, or renal injury as assessed by histological scoring and measurement of blood urea nitrogen. It is concluded that CYP4F18 is necessary for omega oxidation of leukotriene B4 in neutrophils, and is not compensated by other CYP enzymes, but loss of this metabolic pathway is not sufficient to impact inflammation and injury following renal ischemia-reperfusion in mice. PMID:24632148

  10. The Electronegativity Analysis of c-C4F8 as a Potential Insulation Substitute of SF6

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoling; Jiao, Juntao; Li, Bing; Xiao, Dengming

    2016-03-01

    The density distributions related to gas electronegativity for c-C4F8 gas, including negative ion, electron number and electron energy densities in the discharge process, are derived theoretically in both plane-to-plane and point-to-plane electrode geometries. These calculations have been performed through the Boltzmann equation in the condition of a steady-state Townsend (SST) experiment and a fluid model in the condition of both uniform and non-uniform electric fields. The electronegativity coefficients a = n-/ne of c-C4F8 and SF6 are compared to further describe the electron affinity of c-C4F8. The result shows that c-C4F8 represents an obvious electron-attachment performance in the discharge process. However, c-C4F8 still has much weaker gas electronegativity than SF6, whose electronegativity coefficient is lower than that of SF6 by at least three orders of magnitude. supported by National Natural Science Foundation of China (No. 51337006)

  11. Association of the CYP4F2 rs2108622 genetic polymorphism with hypertension: a meta-analysis.

    PubMed

    Luo, X-H; Li, G-R; Li, H-Y

    2015-01-01

    Previous case-control studies on the relationship between the CYP4F2 gene rs2108622 polymorphism and hypertension have produced contrasting results. In this study, we aimed to further evaluate the relationship between the CYP4F2 gene rs2108622 polymorphism and hypertension. We selected four case-control studies related to the CYP4F2 gene rs2108622 polymorphism and hypertension by searching PubMed, EMBase, the Chinese Biomedical Literature Database, and the Wanfang database. We utilized the Cochran Q-test and the I2 index to measure the heterogeneity across studies. To merge the odds ratio (OR) and the 95% confidence interval (95%CI), we utilized the fixed and random-effect models during the analyses. The present study included 1878 patients with hypertension and 1512 healthy control subjects. By meta-analysis, we did not find any association of the CYP4F2 gene rs2108622 polymorphism with hypertension in either genotype or allele distribution [AA+AG vs GG: OR = 1.18, 95%CI (0.91-1.54), P = 0.21; GG+AG vs AA: OR = 0.91, 95%CI (0.80-1.05), P = 0.20; A allele vs G allele: OR = 1.04, 95%CI (0.93-1.16), P = 0.53]. We concluded that the CYP4F2 gene rs2108622 polymorphism was not associated with hypertension. PMID:26634476

  12. Cloning, sequence analysis, and expression of the large subunit of the human lymphocyte activation antigen 4F2

    SciTech Connect

    Lumadue, J.A.; Glick, A.B.; Ruddle, F.H.

    1987-12-01

    Among the earliest expressed antigens on the surface of activated human lymphocytes is the surface antigen 4F2. The authors have used DNA-mediated gene transfer and fluorescence-activated cell sorting to obtain cell lines that contain the gene encoding the large subunit of the human 4F2 antigen in a mouse L-cell background. Human DNAs cloned from these cell lines were subsequently used as hybridization probes to isolate a full-length cDNA clone expressing 4F2. Sequence analysis of the coding region has revealed an amino acid sequence of 529 residues. Hydrophobicity plotting has predicted a probable structure for the protein that includes an external carboxyl terminus, an internal leader sequence, a single hydrophobic transmembrane domain, and two possible membrane-associated domains. The 4F2 cDNA detects a single 1.8-kilobase mRNA in T-cell and B-cell lines. RNA gel blot analysis of RNA derived from quiescent and serum-stimulated Swiss 3T3 fibroblasts reveals a cell-cycle modulation of 4F2 gene expression: the mRNA is present in quiescent fibroblasts but increases 8-fold 24-36 hr after stimulation, at the time of maximal DNA synthesis.

  13. XPS and SEM characterization of electrodeposited transition metals on zirconia

    NASA Astrophysics Data System (ADS)

    Ikonomov, J.; Stoychev, D.; Marinova, Ts

    2000-07-01

    The structure and chemical composition of electrochemically deposited cobalt, copper and cobalt+copper on zirconia have been investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and scanning Auger microscopy (SAM) methods. It has been established that as-deposited metal crystallites are mainly formed on the macroconcavities of an electrochemically roughened SS 1.4301 substrate. In the facet zones, the crystallites are much smaller and have a good dispersion. In this case, the cobalt on the surface is present as Co 2+, while copper is found as Cu +. The deposited metal crystallites show no substantial changes in structure after thermal oxidation, which leads to the formation of considerably thicker oxide layers on the metal crystallites where cobalt and copper are in the Co 3+ nd Cu 2+ states. The cobalt and copper oxides obtained on ZrO 2 are characterized by good adhesion and cause no change in the specific surface area of porous zirconia films. Modification of the structure, composition and dispersion of the oxide systems under consideration is promising, with a view to their application as thin porous inorganic catalytic films.

  14. XPS-XRF hybrid metrology enabling FDSOI process

    NASA Astrophysics Data System (ADS)

    Hossain, Mainul; Subramanian, Ganesh; Triyoso, Dina; Wahl, Jeremy; Mcardle, Timothy; Vaid, Alok; Bello, A. F.; Lee, Wei Ti; Klare, Mark; Kwan, Michael; Pois, Heath; Wang, Ying; Larson, Tom

    2016-03-01

    Planar fully-depleted silicon-on-insulator (FDSOI) technology potentially offers comparable transistor performance as FinFETs. pFET FDOSI devices are based on a silicon germanium (cSiGe) layer on top of a buried oxide (BOX). Ndoped interfacial layer (IL), high-k (HfO2) layer and the metal gate stacks are then successively built on top of the SiGe layer. In-line metrology is critical in precisely monitoring the thickness and composition of the gate stack and associated underlying layers in order to achieve desired process control. However, any single in-line metrology technique is insufficient to obtain the thickness of IL, high-k, cSiGe layers in addition to Ge% and N-dose in one single measurement. A hybrid approach is therefore needed that combines the capabilities of more than one measurement technique to extract multiple parameters in a given film stack. This paper will discuss the approaches, challenges, and results associated with the first-in-industry implementation of XPS-XRF hybrid metrology for simultaneous detection of high-k thickness, IL thickness, N-dose, cSiGe thickness and %Ge, all in one signal measurement on a FDSOI substrate in a manufacturing fab. Strong correlation to electrical data for one or more of these measured parameters will also be presented, establishing the reliability of this technique.

  15. Universal quantification of elastic scattering effects in AES and XPS

    NASA Astrophysics Data System (ADS)

    Jablonski, Aleksander

    1996-09-01

    Elastic scattering of photoelectrons in a solid can be accounted for in the common formalism of XPS by introducing two correction factors, βeff and Qx. In the case of AES, only one correction factor, QA, is required. As recently shown, relatively simple analytical expressions for the correction factors can be derived from the kinetic Boltzmann equation within the so-called "transport approximation". The corrections are expressed here in terms of the ratio of the transport mean free path (TRMFP) to the inelastic mean free path (IMFP). Since the available data for the TRMFP are rather limited, it was decided to complete an extensive database of these values. They were calculated in the present work for the same elements and energies as in the IMFP tabulation published by Tanuma et al. An attempt has been made to derive a predictive formula providing the ratios of the TRMFP to the IMFP. Consequently, a very simple and accurate algorithm for calculating the correction factors βeff, Qx and QA has been developed. This algorithm can easily be generalized to multicomponent solids. The resulting values of the correction factors were found to compare very well with published values resulting from Monte Carlo calculations.

  16. Pressure-enhanced superconductivity in Eu3Bi2S4F4

    DOE PAGESBeta

    Luo, Yongkang; Zhai, Hui -Fei; Zhang, Pan; Xu, Zhu -An; Cao, Guang -Han; Thompson, J. D.

    2014-12-17

    The pressure effect on the newly discovered charge-transferred BiS2-based superconductor, Eu3Bi2S4F4, with a Tc of 1.5 K at ambient pressure, is investigated by transport and magnetic measurements. Accompanied with the enhancement of metallicity under pressures, the onset superconducting transition temperature increases abruptly around 1.0 GPa, reaching ~10.0 K at 2.26 GPa. Alternating current magnetic susceptibility measurements indicate that a new superconducting phase with a higher Tc emerges and dominates at high pressures. In the broad pressure window of 0.68GPa≤p≤2.00 GPa, the high-Tc phase coexists with the low-Tc phase. Hall effect measurements reveal a significant difference in electronic structures between themore » two superconducting phases. As a result, our work devotes the effort to establish the commonality of pressure effect on the BiS2-based superconductors, and also uncovers the importance of electron carrier density in the high-Tc phase.« less

  17. The function of the Periaxin gene during nerve repair in a model of CMT4F *

    PubMed Central

    Williams, Anna C; Brophy, Peter J

    2002-01-01

    Mutations in the Periaxin (PRX) gene are known to cause autosomal recessive demyelinating Charcot-Marie-Tooth (CMT4F) and Dejerine-Sottas disease. The pathogenesis of these diseases is not fully understood. However, progress is being made by studying both the periaxin-null mouse, a mouse model of the disease, and the protein–protein interactions of periaxin. L-periaxin is a constituent of the dystroglycan–dystrophin-related protein-2 complex linking the Schwann cell cytoskeleton to the extracellular matrix. Although periaxin-null mice myelinate normally, they develop a demyelinating peripheral neuropathy later in life. This suggests that periaxin is required for the stable maintenance of a normal myelin sheath. We carried out sciatic nerve crushes in 6-week-old periaxin-null mice, and, 6 weeks later, found that although the number of myelinated axons had returned to normal, the axon diameters remained smaller than in the contralateral uncrushed nerve. Not only do periaxin-null mice have more hypermyelinated axons than their wild-type counterparts but they also recapitulate this hypermyelination during regeneration. Therefore, periaxin-null mice can undergo peripheral nerve remyelination, but the regulation of peripheral myelin thickness is disrupted. PMID:12090399

  18. Pressure-enhanced superconductivity in Eu3Bi2S4F4

    NASA Astrophysics Data System (ADS)

    Luo, Yongkang; Zhai, Hui-Fei; Zhang, Pan; Xu, Zhu-An; Cao, Guang-Han; Thompson, J. D.

    2014-12-01

    The pressure effect on the newly discovered charge-transferred BiS2-based superconductor, Eu3Bi2S4F4 , with a Tc of 1.5 K at ambient pressure, is investigated by transport and magnetic measurements. Accompanied with the enhancement of metallicity under pressures, the onset superconducting transition temperature increases abruptly around 1.0 GPa, reaching ˜10.0 K at 2.26 GPa. Alternating current magnetic susceptibility measurements indicate that a new superconducting phase with a higher Tc emerges and dominates at high pressures. In the broad pressure window of 0.68 GPa≤p ≤2.00 GPa, the high-Tc phase coexists with the low-Tc phase. Hall effect measurements reveal a significant difference in electronic structures between the two superconducting phases. Our work devotes the effort to establish the commonality of pressure effect on the BiS2-based superconductors, and also uncovers the importance of electron carrier density in the high-Tc phase.

  19. A Search for EUV Emission from the O4f Star Zeta Puppis

    NASA Technical Reports Server (NTRS)

    Waldron, Wayne L.; Vallerga, John

    1996-01-01

    We obtained a 140 ks EUVE observation of the O4f star, zeta Puppis. Because of its low ISM column density and highly ionized stellar wind, a unique EUV window is accessible for viewing between 128 to 140 A, suggesting that this star may he the only O star observable with the EUVE. Although no SW spectrometer wavelength bin had a signal to noise greater than 3, a bin at 136 A had a signal to noise of 2.4. This bin is where models predict the brightest line due to OV emission should occur. We present several EUV line emission models. These models were constrained by fitting the ROSAT PSPC X-ray data and our EUVE data. If the OV emission is real, the best fits to the data suggest that there are discrepancies in our current understanding of EUV/X-ray production mechanisms. In particular, the emission measure of the EUV source is found to be much greater than the total wind emission measure, suggesting that the EUV shock must produce a very large density enhancement. In addition, the location of the EUV and X-ray shocks are found to be separated by approx. 0.3 stellar radii, but the EUV emission region is found to be approx. 400 times larger than the X-ray emission region. We also discuss the implications of a null detection and present relevant upper limits.

  20. 4 f excitations in Ce Kondo lattices studied by resonant inelastic x-ray scattering

    NASA Astrophysics Data System (ADS)

    Amorese, A.; Dellea, G.; Fanciulli, M.; Seiro, S.; Geibel, C.; Krellner, C.; Makarova, I. P.; Braicovich, L.; Ghiringhelli, G.; Vyalikh, D. V.; Brookes, N. B.; Kummer, K.

    2016-04-01

    The potential of resonant inelastic soft x-ray scattering to measure 4 f crystal electric-field excitation spectra in Ce Kondo lattices has been examined. Spectra have been obtained for several Ce systems and show a well-defined structure determined by crystal-field, spin-orbit, and charge-transfer excitations only. The spectral shapes of the excitation spectra can be well understood in the framework of atomic multiplet calculations. For CeCu2Si2 we found notable disagreement between the inelastic x-ray-scattering spectra and theoretical calculations when using the crystal-field scheme proposed from inelastic neutron scattering. Modified sets of crystal-field parameters yield better agreement. Our results also show that, with the very recent improvements of soft x-ray spectrometers in resolution to below 30 meV at the Ce M4 ,5 edges, resonant inelastic x-ray scattering could be an ideal tool to determine the crystal-field scheme in Ce Kondo lattices and other rare-earth compounds.

  1. A 4F2-cross-point phase change memory using nano-crystalline doped GeSbTe material

    NASA Astrophysics Data System (ADS)

    Takaura, Norikatsu; Kinoshita, Masaharu; Tai, Mitsuharu; Ohyanagi, Takasumi; Akita, Kenichi; Morikawa, Takahiro

    2015-04-01

    This paper reports on the use of nano-crystalline doped GeSbTe, or nano-GST, to fabricate a cross-point phase change memory with 4F2 cell size and test results obtained for it. We show the characteristics of a poly-Si diode select device with a high on-off ratio and data writing in a 4F2 memory cell array. The advantages of nano-GST over conventional GeSbTe are presented in terms of neighboring disturbance and 4F2 cross-point array formation. The memory cells’ high drivability, low power, and selective write and read performances are demonstrated. The scalability of the diode current density is also presented.

  2. Chemistry Characterization of Jet Aircraft Engine Particulate by XPS: Results from APEX III

    NASA Technical Reports Server (NTRS)

    Vander Wal, Randy L.; Bryg, Victoria M.

    2014-01-01

    This paper reports XPS analysis of jet exhaust particulate from a B737, Lear, ERJ, and A300 aircraft during the APEX III NASA led field campaign. Carbon hybridization and bonding chemistry are identified by high-resolution scans about the C1s core-shell region. Significant organic content as gauged by the sp3/sp2 ratio is found across engines and platforms. Polar oxygen functional groups include carboxylic, carbonyl and phenol with combined content of 20 percent or more. By lower resolution survey scans various elements including transition metals are identified along with lighter elements such as S, N, and O in the form of oxides. Burning additives within lubricants are probable sources of Na, Ba, Ca, Zn, P and possibly Sn. Elements present and their percentages varied significantly across all engines, not revealing any trend or identifiable cause for the differences, though the origin is likely the same for the same element when observed. This finding suggests that their presence can be used as a tracer for identifying soots from aircraft engines as well as diagnostic for monitoring engine performance and wear.

  3. Effects of X-ray flux on UHMWPE by an XPS Spectrometer

    NASA Astrophysics Data System (ADS)

    Buncick, M. C.; Thomas, D. E.; McKinny, K. S.; Jahan, M. S.

    1997-03-01

    For the last 25 years, Electron Spectroscopy for Chemical Analysis (ESCA) also known as X-ray Photoelectron Spectroscopy (XPS) has been used extensively for the study of polymers. ESCA provides chemical composition, structural data such as polymeric linking, fine structure detail such as endgroup type or branching sites, charge distribution and the nature of valence bonding. While a few studies have shown that certain polymers are damaged by the x-ray flux during measurements, ESCA is considered to be a technique that is relatively free from radiation induced changes in the polymers under study.( D. Briggs and M.P. Seah, Practical Surface Analysis by Auger and X-ray Photoelectron Spectroscopy, John Wiley, NewYork, NY, Chap. 9, (1983). D.R. Wheeler and S.V. Pepper, J. Vac. Sci. Technol., 20 , pp.226-232 (1982).) We present complementary measurements by ESCA and electron spin resonance (ESR) on ultra-high molecular weight polyethylene (UHMWPE). We show that ESCA induces primary free radicals in UHMWPE even for relatively short exposures to the x-ray source for both standard and monochromatic x-ray sources. High resolution core-level spectra do not show any difference between free radical rich and virgin UHMWPE. However, the valence band spectra do show changes after exposure to x-ray flux in ESCA.

  4. Chemistry characterization of jet aircraft engine particulate matter by XPS: Results from APEX III

    NASA Astrophysics Data System (ADS)

    Vander Wal, Randy L.; Bryg, Victoria M.; Huang, Chung-Hsuan

    2016-09-01

    This paper reports X-ray photoelectron spectroscopy (XPS) analysis of jet exhaust particulate matter (PM) from a B737, Lear, ERJ and A300 aircraft during the APEX III NASA led field campaign. Carbon hybridization and bonding chemistry are identified by high-resolution scans about the C1s core-shell region. Significant organic content as gauged by the sp3/sp2 ratio is found across engines and powers. Polar oxygen functional groups include carboxylic, carbonyl and phenol with combined content of 20% or more. By survey scans various elements including transition metals are identified along with lighter elements such as S, N and O in the form of oxides. Additives within lubricants are probable sources of Na, Ba, Ca, Zn, P and possibly Sn. Elements present and their percentages varied significantly across all engines, not revealing any trend or identifiable cause for the differences, though the origin is likely the same for the same element when observed. This finding suggests that their collective presence could serve as an environmental tracer for identifying PM originating from aircraft engines and serving as a diagnostic for engine performance and wear.

  5. ω-Hydroxylation of phylloquinone by CYP4F2 is not increased by α-tocopherol

    PubMed Central

    Farley, Sherry M.; Leonard, Scott W.; Taylor, Alan W.; Birringer, Marc; Edson, Katheryne Z.; Rettie, Allan E.; Traber, Maret G.

    2013-01-01

    Scope The objective of this study was to investigate the initial catabolic step of vitamin E and K metabolism, the ω-hydroxylation by human cytochrome P450 4F2 (CYP4F2). Methods and Results Tocopherol (T) metabolism was compared using rat liver slices incubated with deuterated (d6)-RRR-α-T (d6-α-T), racemic 2S-α-T (2S, 4’RS, 8’RS α-T, 2S-α-T), or d2-γ-T (d2-γ-T). Following comparable uptake of each T by liver slices, twice as much 13’-OH-T was produced from 2S-α-T or d2-γ-T (39 ± 15 or 42 ± 5 pmol/g liver, respectively) as from d6-α-T (17 ± 2, p<0.01). Kinetic studies were conducted using insect microsomes expressing human CYP4F2 incubated with d4-phylloquinone (d4-PK), d6-RRR-α-T, d3-SRR-α-T, or d2-γ-T. CYP4F2 demonstrated similar apparent maximal velocities (Vmax) when either of the α-Ts were used as substrates, which were less than the apparent d4-PK Vmax (p<0.0002), while the CYP4F2 catalytic efficiency towards d4-PK (15.8 Vmax/Km) was 5-times greater than for α-Ts. Vitamin K had no effect on vitamin E catabolism, while vitamin E slightly decreased the d4-PK Vmax. Conclusions CYP4F2 discriminates between Ts and PK in vitro, but α-T does not apparently increase PK ω-hydroxylation by this mechanism. PMID:23650179

  6. Structural changes and self-activated photoluminescence in reductively annealed Sr{sub 3}AlO{sub 4}F

    SciTech Connect

    Green, Robert; Avdeev, Maxim; Vogt, Thomas

    2015-08-15

    White light emission of self-activated photoluminescence (PL) in Sr{sub 3}AlO{sub 4}F under 254 nm light is only observed after annealing in a reducing atmosphere of 5%H{sub 2}/95%Ar. High-resolution neutron powder diffraction reveals that the FSr{sub 6} octahedrons and AlO{sub 4} tetrahedrons in this anti-perovskite structure are closer packed in reduced than in air-annealed samples which show no PL. Careful analysis of temperature-dependent neutron powder diffraction data establishes smaller isotropic displacement parameters for Sr(1) and O in Sr{sub 3}AlO{sub 4}F annealed in a reducing atmosphere indicating that the denser packing of the polyhedral sub-units leads to a slightly deeper potential for the Sr(1) and O atoms. Both the air- and reductively-annealed samples have identical thermal expansion within the temperature range between 3 and 350 K. The Debye temperatures were calculated using the atomic displacement parameters and show no significant differences between the air and reductively annealed samples making the Debye temperature a bad proxy for self-activated PL. - Graphical abstract: Annealing Sr{sub 3}AlO{sub 4}F under reducing conditions results in an intense self-activated photoluminescence which is correlated with a denser packing of FSr{sub 6} and AlO{sub 4} polyhedra. - Highlights: • Sr{sub 3}AlO{sub 4}F made in air does not show self-activated photoluminescence. • Only when annealing Sr{sub 3}AlO{sub 4}F in a reducing gas is photoluminescence observed. • FSr{sub 6} and AlO{sub 4} polyhedra in reduced Sr{sub 3}AlO{sub 4}F structure are packed more efficient. • Smaller displacement parameters are found for under-bonded Sr(1) and O sites.

  7. Superconductivity in KCa2Fe4As4F2 with Separate Double Fe2As2 Layers.

    PubMed

    Wang, Zhi-Cheng; He, Chao-Yang; Wu, Si-Qi; Tang, Zhang-Tu; Liu, Yi; Ablimit, Abduweli; Feng, Chun-Mu; Cao, Guang-Han

    2016-06-29

    We report the synthesis, crystal structure, and physical properties of a quinary iron arsenide fluoride, KCa2Fe4As4F2. The new compound crystallizes in a body-centered tetragonal lattice (space group I4/mmm, a = 3.8684(2) Å, c = 31.007(1) Å, Z = 2) that contains double Fe2As2 conducting layers separated by insulating Ca2F2 layers. Our measurements of electrical resistivity, direct-current magnetic susceptibility, and heat capacity demonstrate bulk superconductivity at 33 K in KCa2Fe4As4F2. PMID:27321364

  8. Resonant photoemission study of the 4f spectral function of cerium in Ce/Fe(100) interfaces

    SciTech Connect

    Witkowski, N.; Bertran, F.; Gourieux, T.; Kierren, B.; Malterre, D.; Panaccione, G. |

    1997-11-01

    In this paper, we present a resonant photoemission study of the cerium 4f spectral function in Ce/Fe(100) interfaces. By covering cerium ultrathin films with lanthanum, we completely suppress the surface contribution of the spectra. Then we show that the cerium atoms at the interface are in an intermediate valent state, whereas the f{sup 1} configuration is stabilized in the top layer. This method allows us to obtain the genuine 4f spectral function of the interface, and could be extended to a study of Ce-based compounds. {copyright} {ital 1997} {ital The American Physical Society}

  9. Thermally Evaporated Iron (Oxide) on an Alumina Barrier Layer, by XPS

    SciTech Connect

    Madaan, Nitesh; Kanyal, Supriya S.; Jensen, David S.; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Linford, Matthew R.

    2013-09-06

    We report the XPS characterization of a thermally evaporated iron thin film (6 nm) deposited on an Si/SiO_2/Al_2O_3 substrate using Al Ka X-rays. An XPS survey spectrum, narrow Fe 2p scan, narrow O 1s, and valence band scan are shown.

  10. Evaluation Metrics for the Paragon XP/S-15

    NASA Technical Reports Server (NTRS)

    Traversat, Bernard; McNab, David; Nitzberg, Bill; Fineberg, Sam; Blaylock, Bruce T. (Technical Monitor)

    1993-01-01

    On February 17th 1993, the Numerical Aerodynamic Simulation (NAS) facility located at the NASA Ames Research Center installed a 224 node Intel Paragon XP/S-15 system. After its installation, the Paragon was found to be in a very immature state and was unable to support a NAS users' workload, composed of a wide range of development and production activities. As a first step towards addressing this problem, we implemented a set of metrics to objectively monitor the system as operating system and hardware upgrades were installed. The metrics were designed to measure four aspects of the system that we consider essential to support our workload: availability, utilization, functionality, and performance. This report presents the metrics collected from February 1993 to August 1993. Since its installation, the Paragon availability has improved from a low of 15% uptime to a high of 80%, while its utilization has remained low. Functionality and performance have improved from merely running one of the NAS Parallel Benchmarks to running all of them faster (between 1 and 2 times) than on the iPSC/860. In spite of the progress accomplished, fundamental limitations of the Paragon operating system are restricting the Paragon from supporting the NAS workload. The maximum operating system message passing (NORMA IPC) bandwidth was measured at 11 Mbytes/s, well below the peak hardware bandwidth (175 Mbytes/s), limiting overall virtual memory and Unix services (i.e. Disk and HiPPI I/O) performance. The high NX application message passing latency (184 microns), three times than on the iPSC/860, was found to significantly degrade performance of applications relying on small message sizes. The amount of memory available for an application was found to be approximately 10 Mbytes per node, indicating that the OS is taking more space than anticipated (6 Mbytes per node).

  11. XPS and AFM Study of GaAs Surface Treatment

    SciTech Connect

    Contreras-Guerrero, R.; Wallace, R. M.; Aguirre-Francisco, S.; Herrera-Gomez, A.; Lopez-Lopez, M.

    2008-11-13

    Obtaining smooth and atomically clean surfaces is an important step in the preparation of a surface for device manufacturing. In this work different processes are evaluated for cleaning a GaAs surface. A good surface cleaning treatment is that which provides a high level of uniformity and controllability of the surface. Different techniques are useful as cleaning treatments depending on the growth process to be used. The goal is to remove the oxygen and carbon contaminants and then form a thin oxide film to protect the surface, which is easy to remove later with thermal desorption mechanism like molecular beam epitaxy (MBE) with minimal impact to the surface. In this study, atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were used to characterize the structure of the surface, the composition, as well as detect oxygen and carbon contaminant on the GaAs surface. This study consists in two parts. The first part the surface was subjected to different chemical treatments. The chemical solutions were: (a)H{sub 2}SO{sub 4}:H{sub 2}O{sub 2}:H{sub 2}O(4:1:100), (b) HCl: H{sub 2}O(1:3), (c)NH{sub 4}OH 29%. The treatments (a) and (b) reduced the oxygen on the surface. Treatment (c) reduces carbon contamination. In the second part we made MOS devices on the surfaces treated. They were characterized by CV and IV electrical measurements. They show frequency dispersion.

  12. XPS Protocol for the Characterization of Pristine and Functionalized Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Sosa, E. D.; Allada, R.; Huffman, C. B.; Arepalli, S.

    2009-01-01

    Recent interest in developing new applications for carbon nanotubes (CNT) has fueled the need to use accurate macroscopic and nanoscopic techniques to characterize and understand their chemistry. X-ray photoelectron spectroscopy (XPS) has proved to be a useful analytical tool for nanoscale surface characterization of materials including carbon nanotubes. Recent nanotechnology research at NASA Johnson Space Center (NASA-JSC) helped to establish a characterization protocol for quality assessment for single wall carbon nanotubes (SWCNTs). Here, a review of some of the major factors of the XPS technique that can influence the quality of analytical data, suggestions for methods to maximize the quality of data obtained by XPS, and the development of a protocol for XPS characterization as a complementary technique for analyzing the purity and surface characteristics of SWCNTs is presented. The XPS protocol is then applied to a number of experiments including impurity analysis and the study of chemical modifications for SWCNTs.

  13. Engineering Magnetic Anisotropy in Nanostructured 3d and 4f Ferromagnets

    NASA Astrophysics Data System (ADS)

    Hsu, Chin-Jui

    Due to the increased demand for clean energy in recent years, there is a need for the scientific community to develop technology to harvest thermal energy which is ubiquitous but mostly wasted in our environment. However, there is still no efficient approach to harvest thermal energy to date. In this study, the theory of thermomagnetic energy harvesting is reviewed and unique applications of multiferroics (ferromagnetic plus ferroelectric) are introduced. Based on an efficiency analysis using experimentally measured magneto-thermal properties of 3d transitional and 4f rare earth ferromagnetic elements, the idea of using single domain ferromagnetic elements to obtain higher thermomagnetic conversion efficiencies is proposed. In order to fabricate a ferromagnetic single domain, the magnetic anisotropy of gadolinium (Gd) and nickel (Ni) is engineered at the nanoscale. Both thin films and nanostructures are fabricated and characterized with a focus on the change of magnetic anisotropy governed by shape, crystal structure, and strain. The fabrication processes include sputtering, e-beam lithography (writing and evaporation), and focused ion beam milling. Characterization techniques involving atomic/magnetic force microscopy, energy dispersive X-ray spectroscopy, magneto-optical Kerr effect magnetometry, superconducting quantum interference device magnetometry, scanning/transmission electron microscopy, and X-ray diffraction will also be discussed. Experimental results show that the magnetic domain structure of nanostructured Ni can be stably controlled with geometric constraints or by strain induced via electric field. The magnetic properties of nanostructured Gd, on the other hand, is sensitive to crystal structure. These results provide critical information toward the use of ferromagnetic nanostructures in thermomagnetic energy harvesting and multiferroic applications.

  14. Electronic and geometric properties of Au nanoparticles on Highly Ordered Pyrolytic Graphite (HOPG) studied using X-ray Photoelectron Spectroscopy (XPS) and Scanning Tunneling Microscopy (STM).

    PubMed

    Lopez-Salido, Ignacio; Lim, Dong Chan; Dietsche, Rainer; Bertram, Nils; Kim, Young Dok

    2006-01-26

    Au nanoparticles grown on mildly sputtered Highly Ordered Pyrolytic Graphite (HOPG) surfaces were studied using Scanning Tunneling Microscopy (STM) and X-ray Photoelectron Spectroscopy (XPS). The results were compared with those of Ag nanoparticles on the same substrate. By varying the defect densities of HOPG and the Au coverages, one can create Au nanoparticles in various sizes. At high Au coverages, the structures of the Au films significantly deviate from the ideal truncated octahedral form: the existence of many steps between different Au atomic layers can be observed, most likely due to a high activation barrier of the diffusion of Au atoms across the step edges. This implies that the particle growth at room temperature is strongly limited by kinetic factors. Hexagonal shapes of Au structures could be identified, indicating preferential growth of Au nanostructures along the (111) direction normal to the surface. In the case of Au, XPS studies reveal a weaker core level shift with decreasing particle size compared to the 3d level in similarly sized Ag particles. Also taking into account the Auger analysis of the Ag particles, the core level shifts of the metal nanoparticles on HOPG can be understood in terms of the metal/substrate charge transfer. Ag is (partially) positively charged, whereas Au negatively charged on HOPG. It is demonstrated that XPS can be a useful tool to study metal-support interactions, which plays an important role for heterogeneous catalysis, for example. PMID:16471654

  15. Lithium transition metal fluorophosphates (Li{sub 2}CoPO{sub 4}F and Li{sub 2}NiPO{sub 4}F) as cathode materials for lithium ion battery from atomistic simulation

    SciTech Connect

    Lee, Sanghun Park, Sung Soo

    2013-08-15

    Lithium transition metal fluorophosphates (Li{sub 2}MPO{sub 4}F, M: Co and Ni) have been investigated from atomistic simulation. In order to predict the characteristics of these materials as cathode materials for lithium ion batteries, structural property, defect chemistry, and Li{sup +} ion transportation property are characterized. The core–shell model with empirical force fields is employed to reproduce the unit-cell parameters of crystal structure, which are in good agreement with the experimental data. In addition, the formation energies of intrinsic defects (Frenkel and antisite) are determined by energetics calculation. From migration energy calculations, it is found that these flurophosphates have a 3D Li{sup +} ion diffusion network forecasting good Li{sup +} ion conducting performances. Accordingly, we expect that this study provides an atomic scale insight as cathode materials for lithium ion batteries. - Graphical abstract: Lithium transition metal fluorophosphates (Li{sub 2}CoPO{sub 4}F and Li{sub 2}NiPO{sub 4}F). Display Omitted - Highlights: • Lithium transition metal fluorophosphates (Li{sub 2}MPO{sub 4}F, M: Co and Ni) are investigated from classical atomistic simulation. • The unit-cell parameters from experimental studies are reproduced by the core–shell model. • Li{sup +} ion conducting Li{sub 2}MPO{sub 4}F has a 3D Li{sup +} ion diffusion network. • It is predicted that Li/Co or Li/Ni antisite defects are well-formed at a substantial concentration level.

  16. XPS and ARPES study of the metal-insulator transition in Mn-substituted Sr3Ru2O7

    NASA Astrophysics Data System (ADS)

    Zhu, Zhihuai; Levy de Castro, G.; Hossain, M. A.; Manju, U.; McCheyney, J. L.; Bostwick, A.; Rotenberg, E.; Yoshida, Y.; Elfimov, I. S.; Panaccione, G.; Damascelli, A.

    2010-03-01

    We have studied the metal-insulator transition in Mn-substituted Sr3Ru2O7 by core-level x-ray photoemission (XPS) and angle-resolved photoemission spectroscopy (ARPES). In XPS, both the surface- and bulk-sensitive spectra show a two-peak structure, corresponding to the well screened and the unscreened excitations. The intensity of the well-screened peak is suppressed upon increasing the concentration of Mn, reflecting a metal-to-insulator transition induced by Mn impurities. In ARPES, changes in Fermi surface topology and band dispersions are observed as the system crosses over from a metal to a - possibly Mott - insulator. We observed a variation and enhancement of the Fermi-surface nesting upon Mn substitution, which might be connected to the emergence of the magnetic superstructure revealed by our resonant elastic soft x-ray scattering results [1].[4pt] [1] M.A. Hossain et al., arXiv:0906.0035 (2009).

  17. Bulk plasma fragmentation in a C{sub 4}F{sub 8} inductively coupled plasma: A hybrid modeling study

    SciTech Connect

    Zhao, Shu-Xia; Zhang, Yu-Ru; Gao, Fei; Wang, You-Nian; Bogaerts, Annemie

    2015-06-28

    A hybrid model is used to investigate the fragmentation of C{sub 4}F{sub 8} inductive discharges. Indeed, the resulting reactive species are crucial for the optimization of the Si-based etching process, since they determine the mechanisms of fluorination, polymerization, and sputtering. In this paper, we present the dissociation degree, the density ratio of F vs. C{sub x}F{sub y} (i.e., fluorocarbon (fc) neutrals), the neutral vs. positive ion density ratio, details on the neutral and ion components, and fractions of various fc neutrals (or ions) in the total fc neutral (or ion) density in a C{sub 4}F{sub 8} inductively coupled plasma source, as well as the effect of pressure and power on these results. To analyze the fragmentation behavior, the electron density and temperature and electron energy probability function (EEPF) are investigated. Moreover, the main electron-impact generation sources for all considered neutrals and ions are determined from the complicated C{sub 4}F{sub 8} reaction set used in the model. The C{sub 4}F{sub 8} plasma fragmentation is explained, taking into account many factors, such as the EEPF characteristics, the dominance of primary and secondary processes, and the thresholds of dissociation and ionization. The simulation results are compared with experiments from literature, and reasonable agreement is obtained. Some discrepancies are observed, which can probably be attributed to the simplified polymer surface kinetics assumed in the model.

  18. New Insights in 4f(12)5d(1) Excited States of Tm(2+) through Excited State Excitation Spectroscopy.

    PubMed

    de Jong, Mathijs; Biner, Daniel; Krämer, Karl W; Barandiarán, Zoila; Seijo, Luis; Meijerink, Andries

    2016-07-21

    Optical excitation of ions or molecules typically leads to an expansion of the equilibrium bond lengths in the excited electronic state. However, for 4f(n-1)5d(1) excited states in lanthanide ions both expansion and contraction relative to the 4f(n) ground state have been reported, depending on the crystal field and nature of the 5d state. To probe the equilibrium distance offset between different 4f(n-1)5d(1) excited states, we report excited state excitation (ESE) spectra for Tm(2+) doped in CsCaBr3 and CsCaCl3 using two-color excited state excitation spectroscopy. The ESE spectra reveal sharp lines at low energies, confirming a similar distance offset for 4f(n-1)5d(t2g)(1) states. At higher energies, broader bands are observed, which indicate the presence of excited states with a different offset. On the basis of ab initio embedded-cluster calculations, the broad bands are assigned to two-photon d-d absorption from the excited state. In this work, we demonstrate that ESE is a powerful spectroscopic tool, giving access to information which cannot be obtained through regular one-photon spectroscopy. PMID:27347766

  19. Carbothermal reduction synthesis of carbon coated Na2FePO4F for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Cui, Dongming; Chen, Shasha; Han, Chang; Ai, Changchun; Yuan, Liangjie

    2016-01-01

    Carbon coated spherical Na2FePO4F particles with typical diameters from 500 nm to 1 μm have been synthesized through an economical carbothermal reduction method with a simple apparatus. Mixed carbon source consists of citric acid and phenolic resin can form highly graphitized carbon and remarkably improve the electrical conductivity. When cycled against lithium, Na2FePO4F/C cathodes deliver maximum discharge capacity of 119 mAh g-1 at a low rate of 0.05 C. Reversible capacity of 110 mAh g-1, 74 mAh g-1 and 52 mAh g-1 can be obtained at 0.1 C, 1 C and 2 C rates, respectively. And after 30 cycles at 0.1 C, 91% of the discharge capacity can still be maintained. The electrochemical kinetic characteristic of electrode material is investigated by EIS and the apparent Li+ diffusion coefficient in the Li/Na2FePO4F system is evaluated to be as high as 1.152 × 10-11 cm2 s-1. This study demonstrates that the practical and economical synthesis process can be a promising way for industrial production of high performance Na2FePO4F/C electrode material for large-scale lithium ion batteries.

  20. A novel frameshift mutation of POU4F3 gene associated with autosomal dominant non-syndromic hearing loss

    SciTech Connect

    Lee, Hee Keun; Park, Hong-Joon; Lee, Kyu-Yup; Park, Rekil; Kim, Un-Kyung

    2010-06-04

    Autosomal dominant mutations in the transcription factor POU4F3 gene are associated with non-syndromic hearing loss in humans; however, there have been few reports of mutations in this gene worldwide. We performed a mutation analysis of the POU4F3 gene in 42 unrelated Koreans with autosomal dominant non-syndromic hearing loss, identifying a novel 14-bp deletion mutation in exon 2 (c.662del14) in one patient. Audiometric examination revealed severe bilateral sensorineural hearing loss in this patient. The novel mutation led to a truncated protein that lacked both functional POU domains. We further investigated the functional distinction between wild-type and mutant POU4F3 proteins using in vitro assays. The wild-type protein was completely localized in the nucleus, while the truncation of protein seriously affected its nuclear localization. In addition, the mutant failed to activate reporter gene expression. This is the first report of a POU4F3 mutation in Asia, and moreover our data suggest that further investigation will need to delineate ethnicity-specific genetic background for autosomal dominant non-syndromic hearing loss within Asian populations.

  1. mTORC1 and CK2 coordinate ternary and eIF4F complex assembly

    PubMed Central

    Gandin, Valentina; Masvidal, Laia; Cargnello, Marie; Gyenis, Laszlo; McLaughlan, Shannon; Cai, Yutian; Tenkerian, Clara; Morita, Masahiro; Balanathan, Preetika; Jean-Jean, Olivier; Stambolic, Vuk; Trost, Matthias; Furic, Luc; Larose, Louise; Koromilas, Antonis E.; Asano, Katsura; Litchfield, David; Larsson, Ola; Topisirovic, Ivan

    2016-01-01

    Ternary complex (TC) and eIF4F complex assembly are the two major rate-limiting steps in translation initiation regulated by eIF2α phosphorylation and the mTOR/4E-BP pathway, respectively. How TC and eIF4F assembly are coordinated, however, remains largely unknown. We show that mTOR suppresses translation of mRNAs activated under short-term stress wherein TC recycling is attenuated by eIF2α phosphorylation. During acute nutrient or growth factor stimulation, mTORC1 induces eIF2β phosphorylation and recruitment of NCK1 to eIF2, decreases eIF2α phosphorylation and bolsters TC recycling. Accordingly, eIF2β mediates the effect of mTORC1 on protein synthesis and proliferation. In addition, we demonstrate a formerly undocumented role for CK2 in regulation of translation initiation, whereby CK2 stimulates phosphorylation of eIF2β and simultaneously bolsters eIF4F complex assembly via the mTORC1/4E-BP pathway. These findings imply a previously unrecognized mode of translation regulation, whereby mTORC1 and CK2 coordinate TC and eIF4F complex assembly to stimulate cell proliferation. PMID:27040916

  2. A high performance hybrid capacitor with Li2CoPO4F cathode and activated carbon anode

    NASA Astrophysics Data System (ADS)

    Karthikeyan, K.; Amaresh, S.; Kim, K. J.; Kim, S. H.; Chung, K. Y.; Cho, B. W.; Lee, Y. S.

    2013-06-01

    For the first time, we report the possibility of utilizing Li2CoPO4F as a novel cathode material for hybrid capacitor applications. Li2CoPO4F powders were prepared by a conventional two-step solid state method. A hybrid cell was fabricated using Li2CoPO4F as the cathode along with activated carbon (AC) as the anode in 1 M LiPF6 dissolved in 1 : 1 EC/DMC electrolyte and its electrochemical properties were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge-discharge (C-D) techniques. The Li2CoPO4F/AC cell is capable of delivering a discharge capacitance of 42 F g-1 at 150 mA g-1 current density within 0-3 V region having excellent coulombic efficiency of over 99% even after 1000 cycles. Furthermore, the Li2CoPO4F/AC cell exhibited excellent rate performance with an energy density of ~24 W h kg-1 at 1100 mA g-1 current and maintained about 92% of its initial value even after 30 000 C-D cycles. Electrochemical impedance spectroscopy was conducted to corroborate the results that were obtained and described.For the first time, we report the possibility of utilizing Li2CoPO4F as a novel cathode material for hybrid capacitor applications. Li2CoPO4F powders were prepared by a conventional two-step solid state method. A hybrid cell was fabricated using Li2CoPO4F as the cathode along with activated carbon (AC) as the anode in 1 M LiPF6 dissolved in 1 : 1 EC/DMC electrolyte and its electrochemical properties were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge-discharge (C-D) techniques. The Li2CoPO4F/AC cell is capable of delivering a discharge capacitance of 42 F g-1 at 150 mA g-1 current density within 0-3 V region having excellent coulombic efficiency of over 99% even after 1000 cycles. Furthermore, the Li2CoPO4F/AC cell exhibited excellent rate performance with an energy density of ~24 W h kg-1 at 1100 mA g-1 current and maintained about 92% of its

  3. Temperature dependent magnetic structure of lithium delithiated LixFeSO4F (x = 0, 1) by Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, In Kyu; Wook Hyun, Sung; Kouh, Taejoon; Shim, In-Bo; Sung Kim, Chul

    2012-04-01

    Recently, lithium iron sulfate compounds have been highly considered for a positive electrode material for lithium ion batteries. In this work, LiFeSO4F and the fully delithiated FeSO4F were prepared by the ionothermal process and chemical oxidation reaction method. The LixFeSO4F (x = 0, 1) samples show the triclinic structure with P-1 space group. In the case of delithiated FeSO4F, changes in lattice parameters were observed due to the disappearance of the Li site while maintaining the triclinic structure. Temperature-dependent magnetic susceptibility curves show the antiferromagnetic (AFM) structure with the ordering temperature of 28 K for LiFeSO4F and 99 K for FeSO4F. Also, temperature-dependent Mössbauer spectra of LiFeSO4F below TN were fitted with two-sets of eight Lorentzian indicating the existence of two different types of Fe2+ ions due to the different hyperfine and electric quadrupole interactions. With the lithium delithiated, the Fe3+ iron ions in FeSO4F exhibit two-sets of six-line patterns due to the electron transfer in FeO4F2 site by lithium delithiation. These suggest that the different AFM ordering in LixFeSO4F can be originated from the Fe2+/Fe3+ magnetic ions with different charge distributions and spin contributions.

  4. The evolution of single-copy Drosophila nuclear 4f-rnp genes: spliceosomal intron losses create polymorphic alleles.

    PubMed

    Feiber, Amy L; Rangarajan, Janaki; Vaughn, Jack C

    2002-10-01

    This study provides the first report in which spliceosomal intron losses within a single-copy gene create functional polymorphic alleles in a population. 4f-rnp has previously been shown to be a nuclear gene that is localized on the X chromosome in D. melanogaster and to have eight short spliceosomal introns. An insect species survey was done via polymerase chain reaction (PCR) amplification and sequencing of a 1028-bp gene fragment spanning introns 4-8, which are located in the 3' half of the gene. The results show that 4f-rnp and (thus far) introns 7 and 8 are at least as old as order Odonata (dragonflies), an early-diverging insect line. Unexpectedly, several species within the dipteran family Drosophilidae were found to contain two differently sized 4f-rnp gene sequence variants, owing to precise in-frame intron losses. Results of single-male D. melanogaster PCR analyses show that the two gene size variants are allelic and that the intron loss mechanism appears to be biased toward the 3' end of the gene. A stable potential stem-loop has been identified in D. melanogaster, predicted to fold the 4f-rnp mRNA 3' terminus into a natural primer for subsequent reverse transcription into cDNA. When results are displayed in a phylogenetic context, multiple independent intron loss events are identified. These observations support a model in which frequently occurring cDNAs have led to numerous independent intron losses via homologous recombination/gene conversion during 4f-rnp gene evolution. The results provide insights into the evolution of intron loss and may lead to improved understanding of the dynamics of this process in natural populations. PMID:12355261

  5. Formation of tavorite-type LiFeSO4F followed by in situ X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Eriksson, Rickard; Sobkowiak, Adam; Ångström, Jonas; Sahlberg, Martin; Gustafsson, Torbjörn; Edström, Kristina; Björefors, Fredrik

    2015-12-01

    The tavorite-type polymorph of LiFeSO4F has recently attracted substantial attention as a positive electrode material for lithium ion batteries. The synthesis of this material is generally considered to rely on a topotactic exchange of water (H2O) for lithium (Li) and fluorine (F) within the structurally similar hydrated iron sulfate precursor (FeSO4·H2O) when reacted with lithium fluoride (LiF). However, there have also been discussions in the literature regarding the possibility of a non-topotactic reaction mechanism between lithium sulfate (Li2SO4) and iron fluoride (FeF2) in tetraethylene glycol (TEG) as reaction medium. In this work, we use in situ X-ray diffraction to continuously follow the formation of LiFeSO4F from the two suggested precursor mixtures in a setup aimed to mimic the conditions of a solvothermal autoclave synthesis. It is demonstrated that LiFeSO4F is formed directly from FeSO4·H2O and LiF, in agreement with the proposed topotactic mechanism. The Li2SO4 and FeF2 precursors, on the other hand, are shown to rapidly transform into FeSO4·H2O and LiF with the water originating from the highly hygroscopic TEG before a subsequent formation of LiFeSO4F is initiated. The results highlight the importance of the FeSO4·H2O precursor in obtaining the tavorite-type LiFeSO4F, as it is observed in both reaction routes.

  6. Silicon etch using SF{sub 6}/C{sub 4}F{sub 8}/Ar gas mixtures

    SciTech Connect

    Bates, Robert L.; Stephan Thamban, P. L.; Goeckner, Matthew J.; Overzet, Lawrence J.

    2014-07-01

    While plasmas using mixtures of SF{sub 6}, C{sub 4}F{sub 8}, and Ar are widely used in deep silicon etching, very few studies have linked the discharge parameters to etching results. The authors form such linkages in this report. The authors measured the optical emission intensities of lines from Ar, F, S, SF{sub x}, CF{sub 2}, C{sub 2}, C{sub 3}, and CS as a function of the percentage C{sub 4}F{sub 8} in the gas flow, the total gas flow rate, and the bias power. In addition, the ion current density and electron temperature were measured using a floating Langmuir probe. For comparison, trenches were etched of various widths and the trench profiles (etch depth, undercut) were measured. The addition of C{sub 4}F{sub 8} to an SF{sub 6}/Ar plasma acts to reduce the availability of F as well as increase the deposition of passivation film. Sulfur combines with carbon in the plasma efficiently to create a large optical emission of CS and suppress optical emissions from C{sub 2} and C{sub 3}. At low fractional flows of C{sub 4}F{sub 8}, the etch process appears to be controlled by the ion flux more so than by the F density. At large C{sub 4}F{sub 8} fractional flows, the etch process appears to be controlled more by the F density than by the ion flux or deposition rate of passivation film. CF{sub 2} and C{sub 2} do not appear to cause deposition from the plasma, but CS and other carbon containing molecules as well as ions do.

  7. Toward a W4-F12 approach: Can explicitly correlated and orbital-based ab initio CCSD(T) limits be reconciled?

    PubMed

    Sylvetsky, Nitai; Peterson, Kirk A; Karton, Amir; Martin, Jan M L

    2016-06-01

    In the context of high-accuracy computational thermochemistry, the valence coupled cluster with all singles and doubles (CCSD) correlation component of molecular atomization energies presents the most severe basis set convergence problem, followed by the (T) component. In the present paper, we make a detailed comparison, for an expanded version of the W4-11 thermochemistry benchmark, between, on the one hand, orbital-based CCSD/AV{5,6}Z + d and CCSD/ACV{5,6}Z extrapolation, and on the other hand CCSD-F12b calculations with cc-pVQZ-F12 and cc-pV5Z-F12 basis sets. This latter basis set, now available for H-He, B-Ne, and Al-Ar, is shown to be very close to the basis set limit. Apparent differences (which can reach 0.35 kcal/mol for systems like CCl4) between orbital-based and CCSD-F12b basis set limits disappear if basis sets with additional radial flexibility, such as ACV{5,6}Z, are used for the orbital calculation. Counterpoise calculations reveal that, while total atomization energies with V5Z-F12 basis sets are nearly free of BSSE, orbital calculations have significant BSSE even with AV(6 + d)Z basis sets, leading to non-negligible differences between raw and counterpoise-corrected extrapolated limits. This latter problem is greatly reduced by switching to ACV{5,6}Z core-valence basis sets, or simply adding an additional zeta to just the valence orbitals. Previous reports that all-electron approaches like HEAT (high-accuracy extrapolated ab-initio thermochemistry) lead to different CCSD(T) limits than "valence limit + CV correction" approaches like Feller-Peterson-Dixon and Weizmann-4 (W4) theory can be rationalized in terms of the greater radial flexibility of core-valence basis sets. For (T) corrections, conventional CCSD(T)/AV{Q,5}Z + d calculations are found to be superior to scaled or extrapolated CCSD(T)-F12b calculations of similar cost. For a W4-F12 protocol, we recommend obtaining the Hartree-Fock and valence CCSD components from CCSD-F12b/cc-pV{Q,5}Z-F12

  8. Toward a W4-F12 approach: Can explicitly correlated and orbital-based ab initio CCSD(T) limits be reconciled?

    NASA Astrophysics Data System (ADS)

    Sylvetsky, Nitai; Peterson, Kirk A.; Karton, Amir; Martin, Jan M. L.

    2016-06-01

    In the context of high-accuracy computational thermochemistry, the valence coupled cluster with all singles and doubles (CCSD) correlation component of molecular atomization energies presents the most severe basis set convergence problem, followed by the (T) component. In the present paper, we make a detailed comparison, for an expanded version of the W4-11 thermochemistry benchmark, between, on the one hand, orbital-based CCSD/AV{5,6}Z + d and CCSD/ACV{5,6}Z extrapolation, and on the other hand CCSD-F12b calculations with cc-pVQZ-F12 and cc-pV5Z-F12 basis sets. This latter basis set, now available for H-He, B-Ne, and Al-Ar, is shown to be very close to the basis set limit. Apparent differences (which can reach 0.35 kcal/mol for systems like CCl4) between orbital-based and CCSD-F12b basis set limits disappear if basis sets with additional radial flexibility, such as ACV{5,6}Z, are used for the orbital calculation. Counterpoise calculations reveal that, while total atomization energies with V5Z-F12 basis sets are nearly free of BSSE, orbital calculations have significant BSSE even with AV(6 + d)Z basis sets, leading to non-negligible differences between raw and counterpoise-corrected extrapolated limits. This latter problem is greatly reduced by switching to ACV{5,6}Z core-valence basis sets, or simply adding an additional zeta to just the valence orbitals. Previous reports that all-electron approaches like HEAT (high-accuracy extrapolated ab-initio thermochemistry) lead to different CCSD(T) limits than "valence limit + CV correction" approaches like Feller-Peterson-Dixon and Weizmann-4 (W4) theory can be rationalized in terms of the greater radial flexibility of core-valence basis sets. For (T) corrections, conventional CCSD(T)/AV{Q,5}Z + d calculations are found to be superior to scaled or extrapolated CCSD(T)-F12b calculations of similar cost. For a W4-F12 protocol, we recommend obtaining the Hartree-Fock and valence CCSD components from CCSD-F12b/cc-pV{Q,5}Z-F12

  9. XPS study of the formation of ultrathin GaN film on GaAs(1 0 0)

    NASA Astrophysics Data System (ADS)

    Bideux, L.; Monier, G.; Matolin, V.; Robert-Goumet, C.; Gruzza, B.

    2008-04-01

    The nitridation of GaAs(1 0 0) surfaces has been studied using XPS spectroscopy, one of the best surface sensitive techniques. A glow discharge cell was used to produce a continuous plasma with a majority of N atomic species. We used the Ga3d and As3d core levels to monitor the chemical state of the surface and the coverage of the species. A theoretical model based on stacked layers allows to determine the optimal temperature of nitridation. Moreover, this model permits the determination of the thickness of the GaN layer. Varying time of nitridation from 10 min to 1 h, it is possible to obtain GaN layers with a thickness between 0.5 nm and 3 nm.

  10. Stabilization of Tetravalent 4f (Ce), 5d (Hf), or 5f (Th, U) Clusters by the [α-SiW9O34](10-) Polyoxometalate.

    PubMed

    Duval, Sylvain; Béghin, Sébastien; Falaise, Clément; Trivelli, Xavier; Rabu, Pierre; Loiseau, Thierry

    2015-09-01

    The reaction of Na10[α-SiW9O34] with tetravalent metallic cations such as 4f ((NH4)2Ce(NO3)6), 5d (HfCl4), or 5f (UCl4 and Th(NO3)4) in a pH 4.7 sodium acetate buffer solution leads to the formation of four sandwich-type polyoxometalates [Ce4(μ(3)-O)2(SiW9O34)2(CH3COO)2](10-) (1), [U4(μ(3)-O)2(SiW9O34)2(CH3COO)2](10-) (2), [Th3(μ(3)-O)(μ(2)-OH)3(SiW9O34)2](13-) (3), and [Hf3(μ(2)-OH)3(SiW9O34)2](11-) (4). All four compounds consist of a polynuclear cluster fragment stabilized by two [α-SiW9O34](10-) polyanions. Compounds 1 and 2 are isostructural with a tetranuclear core (Ce4, U4), while compound 3 presents a trinuclear Th3 core bearing a μ(3)-O-centered bridge. It is an unprecedented configuration in the case of the thorium(IV) cluster. Compound 4 also possesses a trinuclear Hf3 core but with the absence of the μ(3)-O bridge. The molecules have been characterized by single-crystal X-ray diffraction, (183)W and (29)Si nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis. PMID:26301948

  11. Surface Chemical Composition of Size-fractionated Urban Walkway Aerosols Determined by XPS and ToF-SIMS

    NASA Astrophysics Data System (ADS)

    Wenjuan, Cheng; Lu-Tao, Weng; Yongjie, Li; Arthur, Lau; Chak, Chan; Chi-Ming, Chan

    2013-04-01

    In this study, aerosol particles with sizes ranging from 0.056 to 10 ?m were collected using a ten-stage impactor sampler (MOUDI) from a busy walkway of Hong Kong. The aerosol samples of each stage were examined with X-ray photoelectron spectroscopy (XPS). Size dependent distributions of the detected six key elements (N, S, Ca, Si, O, and C) were revealed together with the chemical states of N, S and C. The results indicated that aliphatic hydrocarbons were the dominant species on the surface of all particles while a small portion of graphitic carbon (due to elemental and aromatic hydrocarbons) was also detected on the surface of the particles with sizes ranging from 0.056 to 0.32 ?m. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Inorganic salts and nitrates were found in coarse-mode particles. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used for detailed surface and near surface composition analysis. Principal component analysis (PCA) of the ToF-SIMS spectra confirmed the XPS results that aromatic hydrocarbons were associated with the nucleation-mode particles. Aliphatic hydrocarbons with O- and N-containing functional groups were associated with accumulation-mode particles and inorganic salts were related to the coarse-mode particles. Depth-profiling experiments were performed on three specific sets of samples (nucleation-, accumulation- and coarse-mode particles) to study their near-surface structures. It showed that organic compounds were concentrated on the very top surface of the coarse-mode particles with inorganics in the core. The accumulation-mode particles had thick coatings of diverse organic compositions. The nucleation-mode particles, which contained

  12. Understanding the Role of NH4F and Al2O3 Surface Co-modification on Lithium-Excess Layered Oxide Li1.2Ni0.2Mn0.6O2

    SciTech Connect

    Liu, Haodong; Qian, Danna; Verde, Michael G; Zhang, Minghao; Baggetto, Loic; An, Ke; Chen, Yan; Carroll, Kyler J; Lau, Derek; Chi, Miaofang; Veith, Gabriel M; Meng, Ying Shirley

    2015-01-01

    In this work we prepared Li1.2Ni0.2Mn0.6O2 (LNMO) using a hydroxide co-precipitation method and investigated the effect of co-modification with NH4F and Al2O3. After surface co-modification, the first cycle Coulombic efficiency of Li1.2Ni0.2Mn0.6O2 improved from 82.7% to 87.5%, and the reversible discharge capacity improved from 253 to 287 mAh g 1 at C/20. Moreover, the rate capability also increased significantly. A combination of neutron diffraction (ND), high-resolution transmission electron microscopy (HRTEM), aberration-corrected scanning transmission electron microscopy (a-STEM)/electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS) revealed the changes of surface structure and chemistry after NH4F and Al2O3 surface co-modification while the bulk properties showed relatively no changes. These complex changes on the material s surface include the formation of an amorphous Al2O3 coating, the transformation of layered material to a spinel-like phase on the surface, the formation of nanoislands of active material, and the partial chemical reduction of surface Mn4+. Such enhanced discharge capacity of the modified material can be primarily assigned to three aspects: decreased irreversible oxygen loss, the activation of cathode material facilitated with preactivated Mn3+ on the surface, and stabilization of the Ni-redox pair. These insights will provide guidance for the surface modification in high-voltage-cathode battery materials of the future.

  13. Understanding the Role of NH4F and Al2O3 Surface Co-modification on Lithium-Excess Layered Oxide Li1.2Ni0.2Mn0.6O2

    DOE PAGESBeta

    Liu, Haodong; Qian, Danna; Verde, Michael G; Zhang, Minghao; Baggetto, Loic; An, Ke; Chen, Yan; Carroll, Kyler J; Lau, Derek; Chi, Miaofang; et al

    2015-01-01

    In this work we prepared Li1.2Ni0.2Mn0.6O2 (LNMO) using a hydroxide co-precipitation method and investigated the effect of co-modification with NH4F and Al2O3. After surface co-modification, the first cycle Coulombic efficiency of Li1.2Ni0.2Mn0.6O2 improved from 82.7% to 87.5%, and the reversible discharge capacity improved from 253 to 287 mAh g 1 at C/20. Moreover, the rate capability also increased significantly. A combination of neutron diffraction (ND), high-resolution transmission electron microscopy (HRTEM), aberration-corrected scanning transmission electron microscopy (a-STEM)/electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS) revealed the changes of surface structure and chemistry after NH4F and Al2O3 surface co-modification whilemore » the bulk properties showed relatively no changes. These complex changes on the material s surface include the formation of an amorphous Al2O3 coating, the transformation of layered material to a spinel-like phase on the surface, the formation of nanoislands of active material, and the partial chemical reduction of surface Mn4+. Such enhanced discharge capacity of the modified material can be primarily assigned to three aspects: decreased irreversible oxygen loss, the activation of cathode material facilitated with preactivated Mn3+ on the surface, and stabilization of the Ni-redox pair. These insights will provide guidance for the surface modification in high-voltage-cathode battery materials of the future.« less

  14. Absorption spectral analysis of 4f-4f transitions for the complexation of Pr(III) and Nd(III) with thiosemicarbazide in absence and presence of Zn(II) in aqueous and organic solvents

    NASA Astrophysics Data System (ADS)

    Anita, K.; Rajmuhon Singh, N.

    2011-10-01

    The complexation of thiosemicarbazide with Pr(III) and Nd(III) in absence and presence of Zn(II), a soft metal ion in aqueous and organic solvents like CH 3OH,CH 3CN, dioxane (C 4H 8O 2) and DMF (C 3H 7NO) and their equimolar mixtures are discussed by employing absorption difference and comparative absorption spectrophotometry. Complexation of thiosemicarbazide with Pr(III) and Nd(III) is indicated by the changes in the absorption intensity following the subsequent changes in the oscillator strength of different 4f-4f bands and Judd-Ofelt intensity ( Tλ) parameters. The other spectral parameters like energy interaction parameters namely Slater-Condon ( Fk), Racah ( Ek), Lande ( ξ4f), Nephelauxetic ratio ( β) and bonding parameters ( b1/2) are further computed to explain the nature of complexation. The difference in the energy parameters with respect to donor atoms and solvents reveal that the chemical environment around the lanthanide ions has great impact on f-f transition and any change in the environment result in modification of the spectra. Various solvents and their equimolar mixtures are also used to discuss the participation of solvents in the complexation.

  15. Analysis of Fe Nanoparticles Using XPS Measurements Under D.C. or Pulsed-Voltage Bias

    SciTech Connect

    Suzer, Sefik; Baer, Donald R.; Engelhard, Mark H.

    2010-06-16

    The impact of solution exposure on the charging properties of oxide coatings on Fe metal-core oxide-shells has been examined by sample biasing during XPS measurements. The Fe nanoparticles were suspended in relatively unreactive acetone and were analyzed after particle containing solutions were deposited on SiO2/Si substrates, and/or Au substrates. The particle and substrate combinations were subjected to ± 10V d.c. biasing in the form of square waves (SQW) pulses with 5V amplitude. The samples experienced variable degrees of charging for which low energy electrons at ~1 eV, 20μA and low energy Ar+ ions were used to minimize. Application of d.c. bias and/or square wave pulses drastically influences the extent of charging, which is utilized to gather additional analytical information about the sample under investigation. This approach allows separation of otherwise overlapping peaks. Accordingly, the O1s peaks of the silicon oxide substrate, the iron oxide nanoparticles, and that of the casting solvent can be separated from each other. Similarly the C1s peak belonging to the solvent can be separated from that of the adventitious carbon. The charging shifts of the iron nanoparticles are strongly influenced by the surrounding solvent. Hence, acetone exhibits the largest shift, water the smallest, and methanol in between. Dynamical measurements performed by application of the voltage stress in the form of SQW pulses gives information about the time constants of the processes involved, which led us postulate that these charging properties we probe in these systems, stem mainly from ionic movement(s).

  16. Combined PIXE and XPS analysis on republican and imperial Roman coins

    NASA Astrophysics Data System (ADS)

    Daccà, A.; Prati, P.; Zucchiatti, A.; Lucarelli, F.; Mandò, P. A.; Gemme, G.; Parodi, R.; Pera, R.

    2000-03-01

    A combined PIXE and XPS analysis has been performed on a few Roman coins of the republican and imperial age. The purpose was to investigate via XPS the nature and extent of patina in order to be capable of extracting PIXE data relative to the coins bulk. The inclusion of elements from the surface layer, altered by oxidation and inclusion, is a known source of uncertainty in PIXE analyses of coins, performed to assess the composition and the provenance.

  17. Oxide Etch Behavior in an Inductively Coupled C4F8 Discharge Characterized by Diode Laser Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Anderson, Harold; Barela, Marcus; Courtin, Geoff; Waters, Karla

    2001-10-01

    This study reports on oxide and photoresist etch characteristics in an inductively coupled GEC Reference Cell as a function of reactor source power, bias power and pressure using C4F8. Diode laser absorption spectroscopy (DLAS) has shown that C4F8 is largely dissociated to form C2F4, CF2 and CF in the discharge. Over an oxide surface, CF2 and CF are consumed in the oxide etch process, but only when the bias power is sufficient to keep the oxide surface clean through energetic ion bombardment. For C4F8, this transition occurs at 60 eV (75 W bias power) in the GEC Cell. At higher bias powers (125 W) where oxide etching is fast ( 600 nm/min.), CF2 appears to be the key radical for the etch process since 50 percent (2.7-3.0 mTorr in a 15 mTorr C4F8 discharge) is consumed. These values were obtained by comparing the CF2 concentrations over non-reactive wafer surfaces versus blanket oxide wafer surfaces undergoing etching. CF is shown to display a similar trend, but its concentration is an order of magnitude less than CF2, and consequently cannot account on a mass basis for the amount of reactants necessary to balance the amount of etch products. Over a PR surface, neither CF2 nor CF concentrations vary as a function of PR etch rate. Consequently, they do not appear to be involved in the PR etch mechanism. However, PR etching is also critically dependent on bias power. PR films etch presumably due to energetic ion bombardment that degrades the PR film, making it liable to attack by fluorine.

  18. Nuclear magnetic resonance of Al-27 in topaz, Al2SiO4/F, OH/2.

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Ghose, S.

    1972-01-01

    The Al-27 nuclear quadrupolar coupling constant and asymmetry parameter (eta) in topaz have been determined to be 1.67 (plus or minus 0.03) MHz and 0.38 plus or minus 0.05, respectively. These values and the orientations of the principal axes are consistent with the Fe(3+) paramagnetic resonance data and with the symmetry of the AlO4F2 octahedron.

  19. CYP4F2 affects phenotypic outcome in adrenoleukodystrophy by modulating the clearance of very long-chain fatty acids.

    PubMed

    van Engen, Catherine E; Ofman, Rob; Dijkstra, Inge M E; van Goethem, Tessa Jacobs; Verheij, Eveline; Varin, Jennifer; Vidaud, Michel; Wanders, Ronald J A; Aubourg, Patrick; Kemp, Stephan; Barbier, Mathieu

    2016-10-01

    X-linked adrenoleukodystrophy (ALD) is a severe neurodegenerative disorder caused by the accumulation of very long-chain fatty acids (VLCFA) due to mutations in the ABCD1 gene. The phenotypic spectrum ranges from a fatal cerebral demyelinating disease in childhood (cerebral ALD) to a progressive myelopathy without cerebral involvement in adulthood (adrenomyeloneuropathy). Because ABCD1 mutations have no predictive value with respect to clinical outcome a role for modifier genes was postulated. We report that the CYP4F2 polymorphism rs2108622 increases the risk of developing cerebral ALD in Caucasian patients. The rs2108622 polymorphism (c.1297G>A) results in an amino acid substitution valine for methionine at position 433 (p.V433M). Using cellular models of VLCFA accumulation, we show that p.V433M decreases the conversion of VLCFA into very long-chain dicarboxylic acids by ω-oxidation, a potential escape route for the deficient peroxisomal β-oxidation of VLCFA in ALD. Although p.V433M does not affect the catalytic activity of CYP4F2 it reduces CYP4F2 protein levels markedly. These findings open perspectives for therapeutic interventions in a disease with currently limited treatment options. PMID:27425035

  20. High-resolution electron spectroscopy of lanthanide (Ce, Pr, and Nd) complexes of cyclooctatetraene: The role of 4f electrons

    SciTech Connect

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Yang Dongsheng; Liu Yang

    2013-04-28

    Cerium, praseodymium, and neodymium complexes of 1,3,5,7-cyclooctatetraene (COT) complexes were produced in a laser-vaporization metal cluster source and studied by pulsed-field ionization zero electron kinetic energy spectroscopy and quantum chemical calculations. The computations included the second-order Moller-Plesset perturbation theory, the coupled cluster method with single, double, and perturbative triple excitations, and the state-average complete active space self-consistent field method. The spectrum of each complex exhibits multiple band systems and is assigned to ionization of several low-energy electronic states of the neutral complex. This observation is different from previous studies of M(COT) (M = Sc, Y, La, and Gd), for which a single band system was observed. The presence of the multiple low-energy electronic states is caused by the splitting of the partially filled lanthanide 4f orbitals in the ligand field, and the number of the low-energy states increases rapidly with increasing number of the metal 4f electrons. On the other hand, the 4f electrons have a small effect on the geometries and vibrational frequencies of these lanthanide complexes.

  1. Absence of Novel CYP4F2 and VKORC1 Coding Region DNA Variants in Patients Requiring High Warfarin Doses

    PubMed Central

    Burmester, James K.; Berg, Richard L.; Glurich, Ingrid; Yale, Steven H.; Schmelzer, John R.; Caldwell, Michael D.

    2011-01-01

    Objective Warfarin is an FDA-approved oral anticoagulant for long-term prevention of thromboembolism. Substantial inter-individual variation in dosing requirements and the narrow therapeutic index of this widely-prescribed drug make safe initiation and dose stabilization challenging. Single nucleotide polymorphisms (SNPs) occurring in CYP2C9, VKORC1, and CYP4F2 genes are known to impact dose, and VKORC1 and CYP4F2 polymorphisms are associated with higher therapeutic dose requirements in our cohort. However, the most advanced regression models using personal, clinical, and genetic factors to predict individual stable dose account for only 50% to 60% of the observed variability in stable theapeutic dose in Caucasians. Design and Methods In this study, we used DNA sequence analysis to determine whether additional variants in CYP4F2 and VKORC1 gene coding regions contribute to variable dosing requirements among individuals for whom the actual dose was the highest relative to regression model- predicted dose. Results and Conclusions No novel DNA variants in the coding regions of these genes were identified among subjects requiring high warfarin doses, suggesting that other factors yet to be defined contribute to variability in warfarin dose requirements in this subset of our cohort. PMID:21562135

  2. D-4F reduces EO6 immunoreactivity, SREBP-1c mRNA levels, and renal inflammation in LDL receptor-null mice fed a Western diet.

    PubMed

    Buga, Georgette M; Frank, Joy S; Mottino, Giuliano A; Hakhamian, Ashkan; Narasimha, Ajay; Watson, Andrew D; Yekta, Babak; Navab, Mohamad; Reddy, Srinivasa T; Anantharamaiah, G M; Fogelman, Alan M

    2008-01-01

    LDL receptor-null (LDLR(-/-)) mice on a Western diet (WD) develop endothelial dysfunction and atherosclerosis, which are improved by the apolipoprotein A-I (apoA-I) mimetic peptide D-4F. Focusing on the kidney, LDLR(-/-)mice were fed a WD with D-4F or the inactive control peptide scrambled D-4F (ScD-4F) added to their drinking water. The control mice (ScD-4F) developed glomerular changes, increased immunostaining for MCP-1/CCL2 chemokine, increased macrophage CD68 and F4/80 antigens, and increased oxidized phospholipids recognized by the EO6 monoclonal antibody in both glomerular and tublo-interstitial areas. All of these parameters were significantly reduced by D-4F treatment, approaching levels found in wild-type C57BL/6J or LDLR(-/-) mice fed a chow diet. Sterol-regulatory element binding protein-1c (SREBP-1c) mRNA levels and triglyceride levels were elevated in the kidneys of the control mice (ScD-4F) fed the WD compared with C57BL/6J and LDLR(-/-) mice on chow (P < 0.001 and P < 0.001, respectively) and compared with D-4F-treated mice on the WD (P < 0.01). There was no significant difference in plasma lipids, lipoproteins, glucose, blood pressure, or renal apoB levels between D-4F- and ScD-4F-treated mice. We conclude that D-4F reduced renal oxidized phospholipids, resulting in lower expression of SREBP-1c, which, in turn, resulted in lower triglyceride content and reduced renal inflammation. PMID:17925450

  3. A photoemission study of Au, Ge, and O{sub 2} deposition on NH{sub 4}F etched Si(111)

    SciTech Connect

    Terry, J.; Cao, R.; Wigren, C.; Pianetta, P.

    1994-03-01

    We have studied the interaction of a metal, Au, a semiconductor, Ge, and a non-metal, O{sub 2}, with the NH{sub 4}F etched Si(111) surface with photoemission spectroscopy. Two components were present in Si 2p core level spectra from the H-terminated surface. We observed the flat band condition from the as-etched, n-type, Si(111) surface. We performed stepwise depositions of Au and measured the band bending with photoemission spectroscopy. The Fermi level pinned near mid-gap as Au was deposited onto the as-etched surface. After the deposition of 1 ML of Au, a Au-silicide layer formed. This interfacial component indicated that the passivating H layer was compromised. As the Au coverage was increased, layers of pure Au formed between the bulk silicon and the Au-silicide layer. The observed behavior was nearly identical to that of Au deposition on the Si(111) 7 {times} 7 surface. Next, we tested the ability of the monohydride layer to sustain surfactant assisted growth of Ge. Ge islanding was observed at 400{degree}C indicating that good surfactant growth was not obtained. Although the monohydride layer was not a good surfactant for the Si(111) surface at this temperature, further study at different temperatures is needed to determine the ability of the ideal monohydride layer to act as a surfactant. Finally, we observed no oxidation of the as-etched surface at room temperature upon exposure to molecular oxygen.

  4. 28 CFR Appendix to Part 55 - Jurisdictions Covered Under Sections 4(f)(4) and 203(c) of the Voting Rights Act of 1965, as...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 2 2014-07-01 2014-07-01 false Jurisdictions Covered Under Sections 4(f... REGARDING LANGUAGE MINORITY GROUPS Pt. 55, App. Appendix to Part 55—Jurisdictions Covered Under Sections 4(f)(4) and 203(c) of the Voting Rights Act of 1965, as Amended Jurisdiction Coverage under sec....

  5. 28 CFR Appendix to Part 55 - Jurisdictions Covered Under Sections 4(f)(4) and 203(c) of the Voting Rights Act of 1965, as...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 2 2013-07-01 2013-07-01 false Jurisdictions Covered Under Sections 4(f... REGARDING LANGUAGE MINORITY GROUPS Pt. 55, App. Appendix to Part 55—Jurisdictions Covered Under Sections 4(f)(4) and 203(c) of the Voting Rights Act of 1965, as Amended Jurisdiction Coverage under sec....

  6. Composite Cores

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Spang & Company's new configuration of converter transformer cores is a composite of gapped and ungapped cores assembled together in concentric relationship. The net effect of the composite design is to combine the protection from saturation offered by the gapped core with the lower magnetizing requirement of the ungapped core. The uncut core functions under normal operating conditions and the cut core takes over during abnormal operation to prevent power surges and their potentially destructive effect on transistors. Principal customers are aerospace and defense manufacturers. Cores also have applicability in commercial products where precise power regulation is required, as in the power supplies for large mainframe computers.

  7. Evidence for variation in the optimal translation initiation complex: plant eIF4B, eIF4F, and eIF(iso)4F differentially promote translation of mRNAs.

    PubMed

    Mayberry, Laura K; Allen, M Leah; Dennis, Michael D; Browning, Karen S

    2009-08-01

    Eukaryotic initiation factor (eIF) 4B is known to interact with multiple initiation factors, mRNA, rRNA, and poly(A) binding protein (PABP). To gain a better understanding of the function of eIF4B, the two isoforms from Arabidopsis (Arabidopsis thaliana) were expressed and analyzed using biophysical and biochemical methods. Plant eIF4B was found by ultracentrifugation and light scattering analysis to most likely be a monomer with an extended structure. An extended structure would facilitate the multiple interactions of eIF4B with mRNA as well as other initiation factors (eIF4A, eIF4G, PABP, and eIF3). Eight mRNAs, barley (Hordeum vulgare) alpha-amylase mRNA, rabbit beta-hemoglobin mRNA, Arabidopsis heat shock protein 21 (HSP21) mRNA, oat (Avena sativa) globulin, wheat (Triticum aestivum) germin, maize (Zea mays) alcohol dehydrogenase, satellite tobacco necrosis virus RNA, and alfalfa mosaic virus (AMV) 4, were used in wheat germ in vitro translation assays to measure their dependence on eIF4B and eIF4F isoforms. The two Arabidopsis eIF4B isoforms, as well as native and recombinant wheat eIF4B, showed similar responses in the translation assay. AMV RNA 4 and Arabidopsis HSP21 showed only a slight dependence on the presence of eIF4B isoforms, whereas rabbit beta-hemoglobin mRNA and wheat germin mRNA showed modest dependence. Barley alpha-amylase, oat globulin, and satellite tobacco necrosis virus RNA displayed the strongest dependence on eIF4B. These results suggest that eIF4B has some effects on mRNA discrimination during initiation of translation. Barley alpha-amylase, oat globulin, and rabbit beta-hemoglobin mRNA showed the highest activity with eIF4F, whereas Arabidopsis HSP21 and AMV RNA 4 used both eIF4F and eIF(iso)4F equally well. These results suggest that differential or optimal translation of mRNAs may require initiation complexes composed of specific isoforms of initiation factor gene products. Thus, individual mRNAs or classes of mRNAs may respond to the

  8. An apoA-I mimetic peptide containing a proline residue has greater in vivo HDL binding and anti-inflammatory ability than the 4F peptide.

    PubMed

    Wool, Geoffrey D; Vaisar, Tomas; Reardon, Catherine A; Getz, Godfrey S

    2009-09-01

    Modifying apolipoprotein (apo) A-I mimetic peptides to include a proline-punctuated alpha-helical repeat increases their anti-inflammatory properties as well as allows better mimicry of full-length apoA-I function. This study compares the following mimetics, either acetylated or biotinylated (b): 4F (18mer) and 4F-proline-4F (37mer, Pro). b4F interacts with both mouse HDL (moHDL) and LDL in vitro. b4F in vivo plasma clearance kinetics are not affected by mouse HDL level. Administration of biotinylated peptides to mice demonstrates that b4F does not associate with lipoproteins smaller than LDL in vivo, though it does associate with fractions containing free hemoglobin (Hb). In contrast, bPro specifically interacts with HDL. b4F and bPro show opposite binding responses to HDL by surface plasmon resonance. Administration of acetylated Pro to apoE(-/-) mice significantly decreases plasma serum amyloid A levels, while acetylated 4F does not have this ability. In contrast to previous reports that inferred that 4F associates with HDL in vivo, we systematically examined this potential interaction and demonstrated that b4F does not interact with HDL in vivo but rather elutes with Hb-containing plasma fractions. bPro, however, specifically binds to moHDL in vivo. In addition, the number of amphipathic alpha-helices and their linker influences the anti-inflammatory effects of apoA-I mimetic peptides in vivo. PMID:19433476

  9. An apoA-I mimetic peptide containing a proline residue has greater in vivo HDL binding and anti-inflammatory ability than the 4F peptide

    PubMed Central

    Wool, Geoffrey D.; Vaisar, Tomas; Reardon, Catherine A.; Getz, Godfrey S.

    2009-01-01

    Modifying apolipoprotein (apo) A-I mimetic peptides to include a proline-punctuated α-helical repeat increases their anti-inflammatory properties as well as allows better mimicry of full-length apoA-I function. This study compares the following mimetics, either acetylated or biotinylated (b): 4F (18mer) and 4F-proline-4F (37mer, Pro). b4F interacts with both mouse HDL (moHDL) and LDL in vitro. b4F in vivo plasma clearance kinetics are not affected by mouse HDL level. Administration of biotinylated peptides to mice demonstrates that b4F does not associate with lipoproteins smaller than LDL in vivo, though it does associate with fractions containing free hemoglobin (Hb). In contrast, bPro specifically interacts with HDL. b4F and bPro show opposite binding responses to HDL by surface plasmon resonance. Administration of acetylated Pro to apoE−/− mice significantly decreases plasma serum amyloid A levels, while acetylated 4F does not have this ability. In contrast to previous reports that inferred that 4F associates with HDL in vivo, we systematically examined this potential interaction and demonstrated that b4F does not interact with HDL in vivo but rather elutes with Hb-containing plasma fractions. bPro, however, specifically binds to moHDL in vivo. In addition, the number of amphipathic α-helices and their linker influences the anti-inflammatory effects of apoA-I mimetic peptides in vivo. PMID:19433476

  10. [XPS and Raman spectral analysis of nitrogenated tetrahedral amorphous carbon (ta-C : N) films with different nitrogen content].

    PubMed

    Chen, Wang-Shou; Zhu, Jia-Qi; Han, Jie-Cai; Tian, Gui; Tan, Man-Lin

    2009-01-01

    Nitrogenated tetrahedral amorphous carbon (ta-C : N) films were prepared on the polished C--Si substrates by introducing highly pure nitrogen gas into the cathode region and the depositing chamber synchronously using filtered cathodic vacuum arc (FCVA) technology. The nitrogen content in the films was controlled by changing the flow rate of nitrogen gas. The configuration of ta-C : N films was investigated by means of X-ray photoelectron spectroscopy (XPS) and visible Raman spectroscopy. It was shown that the nitrogen content in the films increased from 0.84 at% to 5.37 at% monotonously when the nitrogen flow rate was varied from 2 seem to 20 sccm. The peak position of C (1s) core level moved towards higher binding energy with the increase in nitrogen content. The shift of C (1s) peak position could be ascribed to the chemical bonding between carbon and nitrogen atoms even though more three-fold coordinated sp2 configuration as in graphite was formed when the films were doped with more nitrogen atoms. Additionally, the half width of C(1s) peak gradually was also broadened with increasing nitrogen content. In order to discover clearly the changing regularities of the microstructure of the films, the XPS C(1s) spectra and Raman spectra were deconvoluted using a Gaussian-Lorentzian mixed lineshape. It was shown that the tetrahedral hybridization component was still dominant even though the ratio of sp2/sp3 obtained from C(1s) spectra rose with the increase in nitrogen content. The Raman measurements demonstrated that the G peak position shifted towards higher frequency from 1,561 to 1,578 cm(-1) and the ratio of ID/IG also rose with the increase in nitrogen content. Both results indicated that the graphitizing tendency could occur with the increase in nitrogen content in the films. PMID:19385255

  11. Adsorption selectivity of Lewis acids and bases on an oxidized Mo(100) surface studied by LEED, Auger, and XPS

    NASA Astrophysics Data System (ADS)

    Henry, R. M.; Walker, B. W.; Stair, P. C.

    1985-06-01

    The adsorption of a wide range of Lewis acids (CO, CO 2, B(OCH 3) 3, B(CH 3) 3, and BF 3) and Lewis bases (NH 3, N(CH 3) 3, NH(CH 3) 2, NH 2CH 3, pyridine, 2,6-dimethylpyridine, pyrrole, water, methanol, ethanol, furan, ethylene, propylene, butene, toluene and benzene) on an oxidized Mo(100) single crystal surface has been studied by LEED, Auger and XPS. The oxidized molybdenum surface was prepared by exposing clean Mo(100) at 1023 K to molecular oxygen in ultrahigh vacuum (UHV) in order to produce an ordered P(2 × 1) surface structure having an atomic oxygen concentration of 1.3-1.5 monolayers. Only the strong Lewis acids B(CH 3) 3 and BF 3 adsorbed and remain on the surface under UHV conditions suggesting that the surface oxygen anions are only weakly basic. Only bases containing nitrogen adsorb strongly on the oxidized surface. No trace of benzene or ethylene could be detected on the surface even after exposures at atmospheric pressure. XPS measurements of the carbon and nitrogen (1s) core levels for gas phase and adsorbed phase NH 2CH 3, pyridine, and 2,6-dimethylpyridine indicate that bonding to the surface is through the nitrogen lone pair electrons consistent with an acid-base interaction. The preference of the oxidized surface for adsorption of lone pair electron donors in comparison to w-electron donors can be understood by considering the geometry of the electron donor orbitals. The results indicate that the overlap of the unperturbed donor and acceptor orbitals is a primary factor in determining adsorption selectivity.

  12. In situ XPS studies of thermally deposited potassium on poly( p-phenylene vinylene) and its ring-substituted derivatives

    NASA Astrophysics Data System (ADS)

    Li, S.; Kang, E. T.; Neoh, K. G.; Ma, Z. H.; Tan, K. L.; Huang, Wei

    2001-09-01

    The interactions of thermally evaporated potassium atoms with poly( p-phenylene vinylene) (PPV) and its soluble derivative, poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) was studied in situ by angle-resolved X-ray photoelectron spectroscopy (XPS). The changes in the C 1s core-level line shape of the polymers, the evolution of the K 2p core-level spectra, and the changes in chemical compositions at the interface with progressive deposition of the metal atoms were carefully monitored. The interactions of the K atoms with the conjugated polymer surfaces were compared with those involving metals of other work functions. Diffusion of the K atoms into the polymers and distinct charge transfer interactions were observed at the interface. The migration of bulk adsorbed oxygen to the surfaces of both polymers during the K deposition process resulted in an increase in oxygen concentration at the K/polymer interfaces. The diffusion of the adsorbed oxygen from the bulk of the conjugated polymer film played a dominant role in the interfacial reactions. The interfacial layer contains mainly oxidized metal and metal-polymer charge transfer species.

  13. XPS and bioactivity study of the bisphosphonate pamidronate adsorbed onto plasma sprayed hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    McLeod, Kate; Kumar, Sunil; Smart, Roger St. C.; Dutta, Naba; Voelcker, Nicolas H.; Anderson, Gail I.; Sekel, Ron

    2006-12-01

    This paper reports the use of X-ray photoelectron spectroscopy (XPS) to investigate bisphosphonate (BP) adsorption onto plasma sprayed hydroxyapatite (HA) coatings commonly used for orthopaedic implants. BPs exhibit high binding affinity for the calcium present in HA and hence can be adsorbed onto HA-coated implants to exploit their beneficial properties for improved bone growth at the implant interface. A rigorous XPS analysis of pamidronate, a commonly used nitrogenous BP, adsorbed onto plasma sprayed HA-coated cobalt-chromium substrates has been carried out, aimed at: (a) confirming the adsorption of this BP onto HA; (b) studying the BP diffusion profile in the HA coating by employing the technique of XPS depth profiling; (c) confirming the bioactivity of the adsorbed BP. XPS spectra of plasma sprayed HA-coated discs exposed to a 10 mM aqueous BP solution (pamidronate) for periods of 1, 2 and 24 h showed nitrogen and phosphorous photoelectron signals corresponding to the BP, confirming its adsorption onto the HA substrate. XPS depth profiling of the 2 h BP-exposed HA discs showed penetration of the BP into the HA matrix to depths of at least 260 nm. The bioactivity of the adsorbed BP was confirmed by the observed inhibition of osteoclast (bone resorbing) cell activity. In comparison to the HA sample, the HA sample with adsorbed BP exhibited a 25-fold decrease in primary osteoclast cells.

  14. Vapor pressures of mixtures of CFC-114 with the potential replacement coolants C{sub 4}F{sub 10} and c-C{sub 4}F{sub 8}

    SciTech Connect

    Trowbridge, L.D.; Otey, M.G.

    1994-09-01

    The U.S. Enrichment Corporation`s production of isotopically enriched uranium depends solely on two plants which utilize the gaseous diffusion process. This process uses large quantities of CFC-114 as an evaporative coolant. CFC-114, however, will be phased out of production at the end of 1995 due to its potential to deplete stratospheric ozone. A search has been underway for substitutes for a number of years. The initial search (1988-89) for an ozone-friendly, commercially available, chemically compatible substitute yielded two candidates, FC-c318 (c-C{sub 4}F{sub 8}) and FC-3110 (C{sub 4}F{sub 10}). The intended mode of replacing coolant was to stage the new coolant into independent subsystems of the plants, so that some systems would continue to operate on CFC-114, and an increasing number would operate on the new coolant. During that changeover process, the possibility of coolant mixing arises in variety of scenarios. This work was intended to generate sufficient experimental information to be able to predict the vapor pressure of coolant mixtures over the range of operating conditions likely to be found in the diffusion plants. Specifically, vapor pressures were measured over the temperature range 322 to 355 K (120{degrees}F to 180{degrees}F) and over the full range of mole fractions for binary mixtures of CFC-114 with FC-3110, and of CFC-114 with FC-c318.

  15. Prediction of the dielectric strength for c-C4F8 mixtures with CF4, CO2, N2, O2 and air by Boltzmann equation analysis

    NASA Astrophysics Data System (ADS)

    Li, Xingwen; Zhao, Hu; Jia, Shenli; Murphy, Anthony B.

    2014-10-01

    The dielectric strength of c-C4F8, and mixtures of c-C4F8 with CF4, CO2, N2, O2 and air, is studied through solution of the Boltzmann equation. The reduced ionization coefficient α/N and reduced attachment coefficient η/N are calculated, allowing the reduced effective ionization coefficient (α-η)/N and the critical reduced electric field strength (E/N)cr (the reduced electric field for which (α-η)/N = 0), to be determined. A high value of (E/N)cr for an electronegative gas, such as those considered here, indicates good insulating properties. It is found that c-C4F8-N2 and c-C4F8-air have very similar (E/N)cr values, higher than those of the other three mixtures, and superior even to that of pure SF6 for c-C4F8 concentrations above 80%. Comparison of the results obtained for c-C4F8 and c-C4F8-N2 with experimental values from the literature supports the validity of the approach taken here and the parameters used.

  16. Angle resolved XPS of monomolecular layer of 5-chlorobenzotriazole on oxidized metallic surface

    NASA Astrophysics Data System (ADS)

    Kazansky, L. P.; Selyaninov, I. A.; Kuznetsov, Yu. I.

    2012-10-01

    Angle resolved XPS is used to study adsorption of 5-chlorobenzotriazole (5-chloroBTAH) on surfaces of the oxidized metals: mild steel, copper and zinc from borate buffer solution (pH 7.4). It is shown that for the metals studied the 5-chloroBTA anions, when adsorbed, form a monomolecular layer whose thickness is ∼6 Å comparable with the size of BTA. As XPS evidences adsorption proceeds with deprotonation of 5-chloroBTAH and formation of the coordination bonds between the lone pair of nitrogens and cation of a metal. Measuring XPS at two different angles unequivocally points out almost vertical arrangement of the anions toward the sample surface, when chlorine atoms form outmost virtual layer.

  17. Description of an optimized ChIP-seq analysis pipeline dedicated to genome wide identification of E4F1 binding sites in primary and transformed MEFs.

    PubMed

    Houlès, Thibault; Rodier, Geneviève; Le Cam, Laurent; Sardet, Claude; Kirsh, Olivier

    2015-09-01

    This Data in Brief report describes the experimental and bioinformatic procedures that we used to analyze and interpret E4F1 ChIP-seq experiments published in Rodier et al. (2015) [10]. Raw and processed data are available at the GEO DataSet repository under the subseries # GSE57228. E4F1 is a ubiquitously expressed zinc-finger protein of the GLI-Kruppel family that was first identified in the late eighties as a cellular transcription factor targeted by the adenoviral oncoprotein E1A13S (Ad type V) and required for the transcription of adenoviral genes (Raychaudhuri et al., 1987) [8]. It is a multifunctional factor that also acts as an atypical E3 ubiquitin ligase for p53 (Le Cam et al., 2006) [2]. Using KO mouse models we then demonstrated that E4F1 is essential for early embryonic development (Le Cam et al., 2004), for proliferation of mouse embryonic cell (Rodier et al., 2015), for the maintenance of epidermal stem cells (Lacroix et al., 2010) [6], and strikingly, for the survival of cancer cells (Hatchi et al., 2007) [4]; (Rodier et al., 2015) [10]. The latter survival phenotype was p53-independent and suggested that E4F1 was controlling a transcriptional program driving essential functions in cancer cells. To identify this program, we performed E4F1 ChIP-seq analyses in primary Mouse Embryonic Fibroblasts (MEF) and in p53(-/-), H-Ras(V12)-transformed MEFs. The program directly controlled by E4F1 was obtained by intersecting the lists of E4F1 genomic targets with the lists of genes differentially expressed in E4F1 KO and E4F1 WT cells (Rodier et al., 2015). We describe hereby how we improved our ChIP-seq analyses workflow by applying prefilters on raw data and by using a combination of two publicly available programs, Cisgenome and QESEQ. PMID:26484288

  18. Apolipoprotein A-I mimetic peptide D-4F promotes human endothelial progenitor cell proliferation, migration, adhesion though eNOS/NO pathway.

    PubMed

    Zhang, Zhengang; Qun, Jianhua; Cao, Chunmei; Wang, Jun; Li, Wei; Wu, Yong; Du, Lin; Zhao, Pei; Gong, Kaizheng

    2012-04-01

    Circulating endothelial progenitor cells (EPCs) have a critical role in endothelial maintenance and repair. Apolipoprotein A-I mimetic peptide D-4F has been shown to posses anti-atherogenic properties via sequestration of oxidized phospholipids, induction of remodeling of high density lipoprotein and promotion of cholesterol efflux from macrophage-derived foam cells. In this study, we test the effects of D-4F on EPC biology. EPCs were isolated from the peripheral venous blood of healthy male volunteers and characterized by 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine-labeled acetylated LDL uptake and ulex europaeus agglutinin binding and flow cytometry. Cell proliferation, migration, adhesion, nitric oxide production and endothelial nitric oxide synthase (eNOS) expression in the absence and presence of D-4F or simvastatin (as a positive control), were assayed. We demonstrated that D-4F significantly enhanced EPC proliferation, migration and adhesion in a dose-dependent manner compared with vehicle. However, all of the favorable effects of D-4F on EPCs were dramatically attenuated by preincubation with NOS inhibitor L-NAME. Further, D-4F also increased nitric oxide production in culture supernatant and the levels of eNOS expression and phosphorylation. The stimulatory effects of D-4F (10 μg/ml) on EPC biology were comparable to 0.5 μM simvastatin. These results suggest that eNOS/NO pathway mediates the functional modulation of EPC biology in response to D-4F treatment and support the notion that the beneficial role of D-4F on EPCs may be one of the important components of its anti-atherogenic potential. PMID:21947883

  19. Potential Hazards Relating to Pyrolysis of c-C{sub 4}F{sub 8}O, n-C{sub 4}F{sub 10}, and c-C{sub 4}F{sub 8} in Selected Gaseous Diffusion Plant Operations

    SciTech Connect

    Trowbridge, L.D.

    2000-03-29

    As part of a program intended to replace the present evaporative coolant at the gaseous diffusion plants (GDPs) with a non-ozone-depleting alternate, a series of investigations of the suitability of candidate substitutes is under way. This report summarizes studies directed at estimating the chemical and thermal stability of three candidate coolants, c-C{sub 4}F{sub 8}, n-C{sub 4}F{sub 10}, and c-C{sub 4}F{sub 8}O, in a few specific environments to be found in gaseous diffusion plant operations. One issue concerning the new coolants is the possibility that they might produce the highly toxic compound perfluoroisobutylene (PFIB) in high-temperature environments. Two specific high-temperature thermal environments are examined, namely the use of a flame test for the presence of coolant vapors and welding in the presence of coolant vapors. A second issue relates to the thermal or chemical decomposition of the coolants in the gaseous diffusion process environment. The primary purpose of the study was to develop and evaluate available data to provide information that will allow the technical and industrial hygiene staff at the GDPs to perform appropriate safety evaluations and to determine the need for field testing or experimental work. The scope of this study included a literature search and an evaluation of the information developed therefrom. Part of that evaluation consists of chemical kinetics modeling of coolant decomposition in the two operational environments. The general conclusions are that PFIB formation is unlikely in either situation but that it cannot be ruled out completely under extreme conditions. The presence of oxygen, moisture, and combustion products will tend to lead to the formation of CF{sub 4} and oxidation products (COF{sub 2}, CO, CO{sub 2}, and HF) rather than PFIB.

  20. Density Functional Study of Structures and Electron Affinities of BrO4F/BrO4F−

    PubMed Central

    Gong, Liangfa; Xiong, Jieming; Wu, Xinmin; Qi, Chuansong; Li, Wei; Guo, Wenli

    2009-01-01

    The structures, electron affinities and bond dissociation energies of BrO4F/BrO4F− species have been investigated with five density functional theory (DFT) methods with DZP++ basis sets. The planar F-Br…O2…O2 complexes possess 3A′ electronic state for neutral molecule and 4A′ state for the corresponding anion. Three types of the neutral-anion energy separations are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The EAad value predicted by B3LYP method is 4.52 eV. The bond dissociation energies De (BrO4F → BrO4-mF + Om) (m = 1–4) and De− (BrO4F− → BrO4-mF− + Om and BrO4F− → BrO4-mF + Om−) are predicted. The adiabatic electron affinities (EAad) were predicted to be 4.52 eV for F-Br…O2…O2 (3A′←4A′) (B3LYP method). PMID:19742128

  1. Contiguous 3 d and 4 f Magnetism: Strongly Correlated 3 d Electrons in YbFe2Al10

    NASA Astrophysics Data System (ADS)

    Khuntia, P.; Peratheepan, P.; Strydom, A. M.; Utsumi, Y.; Ko, K.-T.; Tsuei, K.-D.; Tjeng, L. H.; Steglich, F.; Baenitz, M.

    2014-11-01

    We present magnetization, specific heat, and Al 27 NMR investigations on YbFe2Al10 over a wide range in temperature and magnetic field. The magnetic susceptibility at low temperatures is strongly enhanced at weak magnetic fields, accompanied by a ln (T0/T ) divergence of the low-T specific heat coefficient in zero field, which indicates a ground state of correlated electrons. From our hard-x-ray photoemission spectroscopy study, the Yb valence at 50 K is evaluated to be 2.38. The system displays valence fluctuating behavior in the low to intermediate temperature range, whereas above 400 K, Yb3 + carries a full and stable moment, and Fe carries a moment of about 3.1 μB. The enhanced value of the Sommerfeld-Wilson ratio and the dynamic scaling of the spin-lattice relaxation rate divided by T [(1 /T1T ) 27 ] with static susceptibility suggests admixed ferromagnetic correlations. (1 /T1T ) 27 simultaneously tracks the valence fluctuations from the 4 f Yb ions in the high temperature range and field dependent antiferromagnetic correlations among partially Kondo screened Fe 3 d moments at low temperature; the latter evolve out of an Yb 4 f admixed conduction band.

  2. Magnetotransport studies of superconducting P r4F e2A s2T e1 -xO4

    NASA Astrophysics Data System (ADS)

    Pisoni, A.; Szirmai, P.; Katrych, S.; Náfrádi, B.; Gaál, R.; Karpinski, J.; Forró, L.

    2016-03-01

    We report a study of the electrical transport properties of single crystals of P r4F e2A s2T e1 -xO4 , a recently discovered iron-based superconductor. Resistivity, Hall effect, and magnetoresistance are measured in a broad temperature range revealing the role of electrons as dominant charge carriers. The significant temperature dependence of the Hall coefficient and the violation of Kohler's law indicate multiband effects in this compound. The upper critical field and the magnetic anisotropy are investigated in fields up to 16 T, applied parallel and perpendicular to the crystallographic c axis. Hydrostatic pressure up to 2 GPa linearly increases the critical temperature and the resistivity residual ratio. A simple two-band model is used to describe the transport and magnetic properties of P r4F e2A s2T e1 -xO4 . The model can successfully explain the strongly temperature-dependent negative Hall coefficient and the high magnetic anisotropy, assuming that the mobility of electrons is higher than that of holes.

  3. Poly(A) binding protein abundance regulates eukaryotic translation initiation factor 4F assembly in human cytomegalovirus-infected cells.

    PubMed

    McKinney, Caleb; Perez, Cesar; Mohr, Ian

    2012-04-10

    By commandeering cellular translation initiation factors, or destroying those dispensable for viral mRNA translation, viruses often suppress host protein synthesis. In contrast, cellular protein synthesis proceeds in human cytomegalovirus (HCMV)-infected cells, forcing viral and cellular mRNAs to compete for limiting translation initiation factors. Curiously, inactivating the host translational repressor 4E-BP1 in HCMV-infected cells stimulates synthesis of the cellular poly(A) binding protein (PABP), significantly increasing PABP abundance. Here, we establish that new PABP synthesis is translationally controlled by the HCMV-encoded UL38 mammalian target of rapamycin complex 1-activator. The 5' UTR within the mRNA encoding PABP contains a terminal oligopyrimidine (TOP) element found in mRNAs, the translation of which is stimulated in response to mitogenic, growth, and nutritional stimuli, and proteins encoded by TOP-containing mRNAs accumulated in HCMV-infected cells. Furthermore, UL38 expression was necessary and sufficient to regulate expression of a PABP TOP-containing reporter. Remarkably, preventing the rise in PABP abundance by RNAi impaired eIF4E binding to eIF4G, thereby reducing assembly of the multisubunit initiation factor eIF4F, viral protein production, and replication. This finding demonstrates that viruses can increase host translation initiation factor concentration to foster their replication and defines a unique mechanism whereby control of PABP abundance regulates eIF4F assembly. PMID:22431630

  4. Carbon nanoscroll from C4H/C4F-type graphene superlattice: MD and MM simulation insights.

    PubMed

    Liu, Zilong; Xue, Qingzhong; Tao, Yehan; Li, Xiaofang; Wu, Tiantian; Jin, Yakang; Zhang, Zhongyang

    2015-02-01

    Morphology manipulation opens up a new avenue for controlling and tailoring the functional properties of graphene, enabling the exploration of graphene-based nanomaterials. Through mixing single-side-hydrogenated graphene (C4H) with fluorinated graphene (C4F) on one single sheet, the C4H/C4F-type graphene superlattices can self-scroll at room temperature. We demonstrate using molecular dynamic (MD) simulations that different proportions, sizes, directions of hydrogenation and fluorination, and geometry of graphene have a great influence on the self-scrolling of superlattices into a variety of well-defined carbon nanoscrolls (CNSs), thus providing a controllable approach to tune their structures. Based on molecular mechanics (MM) simulations, the CNSs bear more than eight times the radial pressure than that of their multiwalled carbon nanotube (MWNT) counterparts, and an excellent radial elasticity of CNSs is also shown. Compared with conventional CNSs, these novel CNSs are endowed with more ample and flexible heterogeneous structures due to the on-demand hydrogenation and fluorination. Besides, this work provides a feasible route to achieve the necessary electronic and optical changes to be applied in graphene device applications. PMID:25531924

  5. Hyperfine structure of the 4{f}^{8}5{d}^{2}6s configuration in the Tb atom

    NASA Astrophysics Data System (ADS)

    Furmann, B.; Stefanska, D.; Krzykowski, A.

    2016-01-01

    Within this work new experimental results concerning the hyperfine structure (hfs) in the terbium atom are presented. Hfs constants A and B for eight levels belonging to the even-parity configuration 4{f}85{d}26s were determined, based on the results of measurements performed using the laser-induced fluorescence method in a hollow cathode discharge at 18 spectral lines. The configuration 4{f}85{d}26s in the terbium atom was hitherto very scarcely investigated; for seven of the levels examined within this work results concerning the hfs were obtained for the first time. As a by-product, hfs constants for 12 odd-parity levels, involved as upper levels in the transitions investigated, were also determined. A preliminary attempt at a semi-empirical analysis of Tb I hfs on a multi-configuration basis, based on the results of this work, yielded a value of the one-electron {a}6s10 parameter as well as the respective radial integral {< {r}-3> }6s10, which can be compared with the values along the lanthanide elements series reported in the literature. More conclusive results can certainly be obtained once the experimental database for Tb I becomes more extensive.

  6. An XPS study of the optimum loading of barium on high-silica MFI zeolite

    NASA Astrophysics Data System (ADS)

    Mohamed, M. H.; Abdillahi, M. M.; Abbas, N. M.; Siddiqui, A. B.

    1995-12-01

    X-ray photoelectron spectroscopy (XPS) has been applied to the characterization of barium-impregnated MFI high-silica zeolites which are used for the conversion of methanol to light alkenes. X-ray photoelectron spectroscopy provided information about the degree of the dispersion of the various barium loadings on the silicalite structure, and this information helped in elucidating the observed relationship between the activity/selectivity of the catalysts and the barium loading. The XPS results also helped in predicting that the performance of the catalyst would be optimized at 4 wt% Ba loading which was found to agree with the catalytic conversion of methanol to light alkenes.

  7. Samarium electrodeposited acetate and oxide thin films on stainless steel substrate characterized by XPS

    DOE PAGESBeta

    Myhre, Kristian; Burns, Jonathan; Meyer, Harry; Sims, Nathan; Boll, Rose

    2016-06-01

    Characterization of a samarium thin film deposited on a stainless steel substrate using molecular electrodeposition was carried out using a Thermo Scientific K-Alpha X-ray photoelectron spectrometer. We studied two types of samarium electrodeposition samples, one as-deposited and one heated to 700 °C in an air flow. Survey scans include peaks coming from the stainless steel substrate, such as Fe and Cr. An X-ray photoelectron spectroscopy (XPS) survey spectrum, Sm 3d, C 1s, and O 1s narrow scans are shown. It was determined that the heating process decomposed the deposited Sm acetate to Sm2O3 using XPS.

  8. Prospecting Lighting Applications with Ligand Field Tools and Density Functional Theory: A First-Principles Account of the 4f(7)-4f(6)5d(1) Luminescence of CsMgBr3:Eu(2+).

    PubMed

    Ramanantoanina, Harry; Cimpoesu, Fanica; Göttel, Christian; Sahnoun, Mohammed; Herden, Benjamin; Suta, Markus; Wickleder, Claudia; Urland, Werner; Daul, Claude

    2015-09-01

    The most efficient way to provide domestic lighting nowadays is by light-emitting diodes (LEDs) technology combined with phosphors shifting the blue and UV emission toward a desirable sunlight spectrum. A route in the quest for warm-white light goes toward the discovery and tuning of the lanthanide-based phosphors, a difficult task, in experimental and technical respects. A proper theoretical approach, which is also complicated at the conceptual level and in computing efforts, is however a profitable complement, offering valuable structure-property rationale as a guideline in the search of the best materials. The Eu(2+)-based systems are the prototypes for ideal phosphors, exhibiting a wide range of visible light emission. Using the ligand field concepts in conjunction with density functional theory (DFT), conducted in nonroutine manner, we develop a nonempirical procedure to investigate the 4f(7)-4f(6)5d(1) luminescence of Eu(2+) in the environment of arbitrary ligands, applied here on the CsMgBr3:Eu(2+)-doped material. Providing a salient methodology for the extraction of the relevant ligand field and related parameters from DFT calculations and encompassing the bottleneck of handling large matrices in a model Hamiltonian based on the whole set of 33,462 states, we obtained an excellent match with the experimental spectrum, from first-principles, without any fit or adjustment. This proves that the ligand field density functional theory methodology can be used in the assessment of new materials and rational property design. PMID:26270436

  9. 17 CFR 41.3 - Application for an exemptive order pursuant to section 4f(a)(4)(B) of the Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., or any broker or dealer exempt from floor broker or floor trader registration pursuant to section 4f... Commission may, in its sole discretion, grant the application, deny the application, decline to entertain...

  10. Step-by-step assembly of 4d-4f-3d complex based on heptamolybdate anion

    SciTech Connect

    Wu, Shuting; Deng, Binbin; Jiang, Xiuling; Li, Ronghua; Guo, Jiangbin; Lai, Fulong; Huang, Xihe; Huang, Changcang

    2012-12-15

    Four new complexes, (NH{sub 4}){sub 11.9}[Ln{sub 4.7}(MoO{sub 4})(H{sub 2}O){sub 23}(Mo{sub 7}O{sub 24}){sub 4}]{center_dot}xH{sub 2}O (Ln=Pr, x=34 (1); Ln=Nd, x=19 (2)), [NH{sub 4}]{sub 28}[Ce{sub 8}(MoO{sub 4}){sub 2}(H{sub 2}O){sub 31}(Mo{sub 7}O{sub 24}){sub 8}]{center_dot}74H{sub 2}O (3), and (NH{sub 4}){sub 26}[CoPr{sub 8}(MoO{sub 4}){sub 2}(H{sub 2}O){sub 33}(Mo{sub 7}O{sub 24}){sub 8}]{center_dot}54H{sub 2}O (4) have been synthesized and characterized by single-crystal and powder X-ray diffraction, CHN elemental analyses TGA analyses, IR and UV-Vis spectroscopy. Complex 1-3 are 0D compounds constructed by the connection between Ln{sup III} ions and [Mo{sub 7}O{sub 24}]{sup 6-} unit. In complex 4, the existence of Co{sup II} connects the polyanion clusters into 1D chain. The introduction of 3d metal (cobalt cation) and 4f metal (Ln=Pr{sup III}, Nd{sup III}, Ce{sup III}) encourages the coordination capability for [Mo{sub 7}O{sub 24}]{sup 6-} unit, which shows interesting coordination modes. The [Mo{sub 7}O{sub 24}]{sup 6-} unit in 1-4 shows three new coordination modes, connecting up to four metal cations. Complexes 1-4 show antiferromagnetic behavior via variable temperature magnetic study. The photoluminescence spectrum indicates the photoluminescence property for 4. - Graphical abstract: Heptamolybdate anion shows extraordinary coordination geometry in the presence of both lanthanide cation (Pr{sup III}) and transitional metal cation (Co{sup II}), which give rise to a new 4d-4f-3d complex. Black-Small-Square Highlights: Black-Right-Pointing-Pointer A new 4d-4f-3d complex that containing 1D chain was obtained and discussed. Black-Right-Pointing-Pointer New coordination geometry with higher coordination number of heptamolybdate. Black-Right-Pointing-Pointer Series of heptamolybdate contained complexes were synthesized and characterized. Black-Right-Pointing-Pointer Complexes mentioned above show antiferromagnetic behavior.