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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

    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.

  9. 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.

  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

    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

  6. 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

  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. 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

  19. 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.

  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. 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

  16. 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.

  17. 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.

  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. 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

  3. 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.

  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. 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

  7. 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.

  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. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  10. 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.

  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. 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...

  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. 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.

  3. 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....

  4. 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...

  5. 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...

  6. 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...

  7. 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,...

  8. 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,...

  9. 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,...

  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 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.

  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 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.

  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. 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

  17. 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.

  18. 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.

  19. 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

  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. 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

  9. 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

  10. 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

  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. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  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, 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

  5. 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.

  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. 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

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  1. 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.

  2. 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.

  3. 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

  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. 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

  9. 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.

  10. 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.

  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. 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)

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  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. 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.

  3. 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.

  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. 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.

  11. 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).

  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. 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.

  15. 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

  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. 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.

  18. 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.

  19. 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

  20. 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.

  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. 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.

  5. 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.

  6. 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

  7. 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

  8. 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

  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. 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.

  18. 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.

  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. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  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.

  11. Deteriorated hardened cement paste structure analyzed by XPS and {sup 29}Si NMR techniques

    SciTech Connect

    Kurumisawa, Kiyofumi; Nawa, Toyoharu; Owada, Hitoshi; Shibata, Masahito

    2013-10-15

    In this report, X-ray photoelectron spectroscopy (XPS) and {sup 29}Si-MAS-NMR was used for the evaluation of deteriorated hardened cement pastes. The deterioration by ammonium nitrate solution was accompanied by changes in the pore structure as well as by structural changes in the C–S–H in the hardened cement paste. The CaO/SiO{sub 2} ratio of the C–S–H decreased with the progress of deterioration, there was also polymerization of the silicate in the C–S–H. It was confirmed that the degree of polymerization of silicate of the C–S–H in hardened cement paste can be determined by XPS. It was also shown that the polymerization depends on the structure of the C–S–H. -- Highlights: •The polymerization of silicate of the C–S–H in the HCP can be observed by XPS. •The structure of C–S–H changed with the degree of calcium leaching. •The NMR result about silicate in C–S–H was in good agreement with the XPS result.

  12. Thermally Annealed Iron (Oxide) Thin Film 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

    Herein we show characterization of an Fe thin film on Al_2O_3 after thermal annealing under H_2 using Al Ka X-rays. The XPS survey spectrum, narrow Fe 2p scan, and valence band regions are presented. The survey spectrum shows aluminum signals due to exposure of the underlying Al_2O_3 film during Fe nanoparticle formation.

  13. XPS Study of Oxide/GaAs and SiO2/Si Interfaces

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    Concepts developed in study of SiO2/Si interface applied to analysis of native oxide/GaAs interface. High-resolution X-ray photoelectron spectroscopy (XPS) has been combined with precise chemical-profiling technique and resolution-enhancement methods to study stoichiometry of transitional layer. Results are presented in report now available.

  14. Sputter-induced erosion of alkali metal surfaces - AES, XPS and SIMS studies

    SciTech Connect

    Krauss, A.R.

    1982-01-01

    This paper will discuss the manner in which the techniques of Auger-electron spectroscopy (AES), X-ray-photoelectron spectroscopy (XPS), secondary-ion mass spectroscopy (SIMS) and ion-scattering spectroscopy (ISS) may be used to study the use of high secondary-ion-yield surfaces as a means of reducing plasma-impurity influx in magnetic-confinement fusion devices.

  15. PLA-PMMA blends: A study by XPS and ToF-SIMS

    NASA Astrophysics Data System (ADS)

    Cossement, D.; Gouttebaron, R.; Cornet, V.; Viville, P.; Hecq, M.; Lazzaroni, R.

    2006-07-01

    This paper reports which are the possibilities of quantification by time of flight secondary ion mass spectrometry (ToF-SIMS) for some polymer blends. In order to assess the composition of the mixtures, we studied first different poly( L-lactide)/polymethylmethacrylate (PLA/PMMA) blends by X-ray photoelectron spectroscopy (XPS), this technique being quantitative. By XPS fitting of the C 1s level, we found a very good agreement of the measured concentrations with the initial compositions. Concerning ToF-SIMS data treatment, we used principal component analysis (PCA) on negative spectra allowing to discriminate one polymer from the other one. By partial least square regression (PLS), we found also a good agreement between the ToF-SIMS predicted and initial compositions. This shows that ToF-SIMS, in a similar way to XPS, can lead to quantitative results. In addition, the observed agreement between XPS (60-100 Å depth analyzed) and ToF-SIMS (10 Å depth analyzed) measurements show that there is no segregation of one of the two polymers onto the surface.

  16. X-ray Photoelectron Spectroscopy (XPS), Rutherford Back Scattering (RBS) studies

    NASA Technical Reports Server (NTRS)

    Neely, W. C.; Bozak, M. J.; Williams, J. R.

    1993-01-01

    X-ray photoelectron spectroscopy (XPS), Rutherford Back Scattering (RBS) studies of each of sample received were completed. Since low angle X-ray could not be performed because of instrumentation problems, Auger spectrometry was employed instead. The results of these measurements for each of the samples is discussed in turn.

  17. Structure, stability, and photoluminescence in the anti-perovskites Na3W1-xMoxO4F (0≤x≤1)

    NASA Astrophysics Data System (ADS)

    Sullivan, Eirin; Avdeev, Maxim; Blom, Douglas A.; Gahrs, Casey J.; Green, Robert L.; Hamaker, Christopher G.; Vogt, Thomas

    2015-10-01

    Single-phase ordered oxyfluorides Na3WO4F, Na3MoO4F and their mixed members Na3W1-xMoxO4F can be prepared via facile solid state reaction of Na2MO4·2H2O (M=W, Mo) and NaF. Phases produced from incongruent melts are metastable, but lower temperatures allow for a facile one-step synthesis. In polycrystalline samples of Na3W1-xMoxO4F, the presence of Mo stabilizes the structure against decomposition to spinel phases. Photoluminescence studies show that upon excitation with λ=254 nm and λ=365 nm, Na3WO4F and Na3MoO4F exhibit broad emission maxima centered around 485 nm. These materials constitute new members of the family of self-activating ordered oxyfluoride phosphors with anti-perovskite structures which are amenable to doping with emitters such as Eu3+.

  18. Silver-coated LiVPO4F composite with improved electrochemical performance as cathode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Yang, Bo; Yang, Lin

    2015-12-01

    Nano-structured LiVPO4F/Ag composite cathode material has been successfully synthesized via a sol-gel route. The structural and physical properties, as well as the electrochemical performance of the material are compared with those of the pristine LiVPO4F. X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveal that Ag particles are uniformly dispersed on the surface of LiVPO4F without destroying the crystal structure of the bulk material. An analysis of the electrochemical measurements show that the Ag-modified LiVPO4F material exhibits high discharge capacity, good cycle performance (108.5 mAh g-1 after 50th cycles at 0.1 C, 93% of initial discharge capacity) and excellent rate behavior (81.8 mAh g-1 for initial discharge capacity at 5 C). The electrochemical impedance spectroscopy (EIS) results reveal that the adding of Ag decreases the charge-transfer resistance (Rct) of LiVPO4F cathode. This study demonstrates that Ag-coating is a promising way to improve the electrochemical performance of the pristine LiVPO4F for lithium-ion batteries cathode material.

  19. Comments on the thermoelectric power of intermetallic rare-earth compounds with well localized 4f shells

    NASA Astrophysics Data System (ADS)

    Szukiel, A. E.

    2016-05-01

    The anomalous temperature variation of the thermoelectric power in the metallic rare-earth compounds with well-localized 4f shells is sometimes interpreted as resulting from the conduction electrons scattering in the Born approximation on the acoustic phonons and on the localized spins in the s-f exchange interaction. Such an interpretation relies on the results of some theoretical works where the sign reversal and the maxima of the thermoelectric power were obtained within these simple models. In the present paper we prove that neither the electron-phonon scattering nor the magnetic s-f scattering in the Born approximation (nor both of them) do lead to the effects mentioned above.

  20. Temporal and spatial regulation of translation in the mammalian oocyte via the mTOR–eIF4F pathway

    PubMed Central

    Susor, Andrej; Jansova, Denisa; Cerna, Renata; Danylevska, Anna; Anger, Martin; Toralova, Tereza; Malik, Radek; Supolikova, Jaroslava; Cook, Matthew S.; Oh, Jeong Su; Kubelka, Michal

    2015-01-01

    The fully grown mammalian oocyte is transcriptionally quiescent and utilizes only transcripts synthesized and stored during early development. However, we find that an abundant RNA population is retained in the oocyte nucleus and contains specific mRNAs important for meiotic progression. Here we show that during the first meiotic division, shortly after nuclear envelope breakdown, translational hotspots develop in the chromosomal area and in a region that was previously surrounded the nucleus. These distinct translational hotspots are separated by endoplasmic reticulum and Lamin, and disappear following polar body extrusion. Chromosomal translational hotspots are controlled by the activity of the mTOR–eIF4F pathway. Here we reveal a mechanism that—following the resumption of meiosis—controls the temporal and spatial translation of a specific set of transcripts required for normal spindle assembly, chromosome alignment and segregation. PMID:25629602

  1. Tailoring the coercivity in ferromagnetic ZnO thin films by 3d and 4f elements codoping

    SciTech Connect

    Lee, J. J.; Xing, G. Z. Yi, J. B.; Li, S.; Chen, T.; Ionescu, M.

    2014-01-06

    Cluster free, Co (3d) and Eu (4f) doped ZnO thin films were prepared using ion implantation technique accompanied by post annealing treatments. Compared with the mono-doped ZnO thin films, the samples codoped with Co and Eu exhibit a stronger magnetization with a giant coercivity of 1200 Oe at ambient temperature. This was further verified through x-ray magnetic circular dichroism analysis, revealing the exchange interaction between the Co 3d electrons and the localized carriers induced by Eu{sup 3+} ions codoping. The insight gained with modulating coercivity in magnetic oxides opens up an avenue for applications requiring non-volatility in spintronic devices.

  2. An Opto-VLSI-based reconfigurable optical adddrop multiplexer employing an off-axis 4-f imaging system.

    PubMed

    Shen, Mingya; Xiao, Feng; Ahderom, Selam; Alameh, Kamal

    2009-08-01

    A novel reconfigurable optical add-drop multiplexer (ROADM) structure is proposed and demonstrated experimentally. The ROADM structure employs two arrayed waveguide gratings (AWGs), an array of optical fiber pairs, an array of 4-f imaging microlenses that are offset in relation to the axis of symmetry of the fiber pairs, and a reconfigurable Opto-VLSI processor that switches various wavelength channels between the fiber pairs to achieve add or drop multiplexing. Experimental results are shown, which demonstrate the principle of add/drop multiplexing with crosstalk of less than -27dB and insertion loss of less than 8dB over the Cband for drop and through operation modes. PMID:19654810

  3. DUBLIN CORE

    EPA Science Inventory

    The Dublin Core is a metadata element set intended to facilitate discovery of electronic resources. It was originally conceived for author-generated descriptions of Web resources, and the Dublin Core has attracted broad ranging international and interdisciplinary support. The cha...

  4. The first intron of the 4F2 heavy-chain gene contains a transcriptional enhancer element that binds multiple nuclear proteins

    SciTech Connect

    Karpinski, B.A.; Yang, L.H.; Cacheris, P.; Morle, G.D.; Leiden, J.M.

    1989-06-01

    The authors utilized the human 4F2 heavy-chain (4F2HC) gene as a model system to study the regulation of inducible gene expression during normal human T-cell activation. Previous studies have demonstrated that 4F2HC gene expression is induced during normal T-cell activation and that the activity of the gene is regulated, at least in part, by the interaction of a constitutively active 5'-flanking housekeeping promoter and a phorbol ester-responsive transcriptional attenuator element located in the exon 1-intron 1 region of the gene. They now report that 4F2HC intron 1 contains a transcriptional enhancer element which is active on a number of heterologous promoters in a variety of murine and human cells. This enhancer element has been mapped to a 187-base-pair RsaI-AluI fragment from 4F2HC intron 1. DNase I footprinting and gel mobility shift analyses demonstrated that this fragment contains two nuclear protein-binding sites (NF-4FA and NF-4FB) which flank a consensus binding site for the inducible AP-1 transcription factor. Deletion analysis showed that the NF-4FA, NF-4FB, and AP-1 sequences are each necessary for full enhancer activity. Murine 4F2HC intron 1 displayed enhancer activity similar to that of its human counterpart. Comparison of the sequences of human and murine 4F2HC intron 1s demonstrated that the NF-4FA, NF-4FB, and AP-1 sequence motifs have been highly conserved during mammalian evolution.

  5. Tuning of 4f- and Fe-based correlated electron systems by magnetic field and chemical substitution

    NASA Astrophysics Data System (ADS)

    Hodovanets, Halyna

    Compounds with 3d- and 4f -electrons can often be tuned to manifest new physics and evolve into new ground states with multiple parameters: pressure, magnetic field, and chemical substitution. In this work chemical substitution and magnetic field were used to tune correlated states coming from 3 d- and 4f-electrons. The first part of this thesis summarizes the study of Lifshitz transitions in K- and TM- (TM=Co, Rh, Ru, and Mn) substituted BaFe2As2 single crystals by thermoelectric power (TEP) measurements. The second part of this thesis presents two studies of tuning the low-temperature states of Ce-based materials. The first of these is a comprehensive study of transport and thermodynamic properties of CeZn11 and LaZn 11 single crystals as well as the search for a possible field-induced quantum critical point in CeZn11. CeZn11 orders antiferromagnetically below ~ 2 K. The zero-field resistivity and thermoelectric power data show features characteristic of a Ce-based intermetallic with crystal-electric-field splitting and possible Kondo-lattice effects. The constructed T - H phase diagram for the magnetic field applied along the easy [110] direction shows that the magnetic field required to suppress TN below 0.4 K is in the range of 45-47.5 kOe. A linear behavior of the rho(T) data, H||[110], was observed only for H = 45 kOe for 0.46 K ≤T ≤ 1.96 K followed by the Landau-Fermi-liquid regime for a limited range of fields, 47.5 kOe ≤ H ≤60 kOe. From the analysis of the data, it appears that CeZn11 is a local moment compound with little or no electronic correlations arising from the Ce 4f-shell. Given the very high quality of the single crystals, quantum oscillations are found for both CeZn11 and LaZn11. In order to study a system with clearer Kondo-like features, the effects of La dilution of the Kondo lattice CeCu2Ge2 were studied as well. CeCu2Ge2 orders antiferromagnetically below TN ~ 4 K with the Kondo temperature TK in the range of 4-6 K. The study of

  6. A comparative study on defect estimation using XPS and Raman spectroscopy in few layer nanographitic structures.

    PubMed

    Ganesan, K; Ghosh, Subrata; Gopala Krishna, Nanda; Ilango, S; Kamruddin, M; Tyagi, A K

    2016-08-10

    Defects in planar and vertically oriented nanographitic structures (NGSs) synthesized by plasma enhanced chemical vapor deposition (PECVD) have been investigated using Raman and X-ray photoelectron spectroscopy. While Raman spectra reveal the dominance of vacancy and boundary type defects respectively in vertical and planar NGSs, XPS provides additional information on vacancy related defect peaks in the C 1s spectrum, which originate from non-conjugated carbon atoms in the hexagonal lattice. Although an excellent correlation prevails between these two techniques, our results show that estimation of surface defects by XPS is more accurate than Raman analysis. Nuances of these techniques are discussed in the context of assessing defects in nanographitic structures. PMID:27445041

  7. RECENT XPS STUDIES OF THE EFFECT OF PROCESSING ON NB SRF SURFACES

    SciTech Connect

    Hui Tian; Binping Xiao; Michael Kelley; Charles Reece; A. Demasi; L. Pipe; Kevin Smith

    2008-02-12

    XPS studies have consistently shown that Nb surfaces for SRF chiefly comprise of a few nm of Nb2O5 on top of Nb metal, with minor amounts of Nb sub-oxides. Nb samples after BCP/EP treatment with post-baking at the various conditions have been examined by using synchrotron based XPS. Despite the confounding influence of surface roughness, certain outcomes are clear. Lower-valence Nb species are always and only associated with the metal/oxide interface, but evidence for an explicit layer structure or discrete phases is lacking. Post-baking without air exposure shows decreased oxide layer thickness and increased contribution from lower valence species, but spectra obtained after subsequent air exposure cannot be distinguished from those obtained prior to baking, though the SRF performance improvement remains.

  8. Structural evolution of Ga-Ge-Te glasses by combined EXAFS and XPS analysis

    SciTech Connect

    Golovchak, R.; Calvez, L.; Bureau, B.; Jain, H.

    2013-08-07

    The structural evolution of Ga{sub x}Ge{sub y}Te{sub 100−x−y} glasses in the vicinity of GeTe{sub 4}-GaTe{sub 3} pseudo-binary tie-line is determined with high-resolution X-ray photoelectron (XPS) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The analysis of XPS data is complicated by similar electronegativity values for the constituent chemical elements, but then the interpretation is facilitated by information from complementary EXAFS analysis of the structure around each element independently. The results show 4/4/2 coordination for Ga/Ge/Te atoms and absence of Ga(Ge)-Ge(Ga) bonds or extended Te clusters in significant concentrations within the whole range of studied composition. The observed structural features correlate well with the measured basic physical properties of Ga-containing germanium telluride glasses.

  9. Decay characterization of glassy pigments: an XPS investigation of smalt paint layers

    NASA Astrophysics Data System (ADS)

    Altavilla, C.; Ciliberto, E.

    The identification and characterization of a particular pigment in an art object or in a paint layer is an important step in the history of art and technology. Moreover, the understanding of deterioration mechanisms is an essential prerequisite for diagnostics and restoration. In this work we used X-ray photoelectron spectroscopy (XPS) to study pure smalt (cobalt-based blue pigment) and smalt in a tempera media (`leather-glue'). XPS was used to characterize the pure pigment efficiently and to distinguish it in real paint layers. We also studied smalt in leather-glue samples aged in a climatic chamber to investigate the effects of weathering and pollutant concentration on the deterioration process of this paint system.

  10. An XPS study of gold deposition at low temperatures on sulfide minerals: Reducing agents

    SciTech Connect

    Hyland, M.M.; Bancroft, G.M. )

    1989-02-01

    The reduction of KAuCl{sub 4} to metallic gold by pyrite, high iron content sphalerite and galena was studied using surface analytical and solution techniques, including X-ray photoelectron spectroscopy (XPS) and atomic absorption spectroscopy (A.A.). High resolution XPS of the reacted mineral showed that the mineral surface is the Au reducing agent. On galena and high iron sphalerite, a corroded layer forms rapidly as S{sup 2 minus} is oxidized to polysulfides, S{sup 2{minus}}{sub x}, and the metals are leached from the surface. Although Au is also reduced on pyrite, the formation of surface polysulfide is not concurrent with Au reduction. Solution analysis for the pyrite and high iron sphalerite reactions shows, however, that considerable sulfate is produced due to the oxidation of S{sup 2{minus}}, S{sup 2{minus}}{sub 2} or the intermediate polysulphide.

  11. GD-OES and XPS coupling: A new way for the chemical profiling of photovoltaic absorbers

    NASA Astrophysics Data System (ADS)

    Mercier, Dimitri; Bouttemy, Muriel; Vigneron, Jackie; Chapon, Patrick; Etcheberry, Arnaud

    2015-08-01

    In this paper, we examine the complementarity of Glow Discharge Optical Emission Spectroscopy (GD-OES) and X Ray Photoelectron Spectroscopy (XPS) for the realization of fine chemical depth profiling of photovoltaic absorbers using Cu(In,Ga)Se2 (CIGS) materials. The possibility to use sequentially these two techniques is discussed in this paper. We have evaluated the chemical modifications of the crater after GD-OES analyses which depend on the manner of finishing the plasma etching sequence; and we propose different ways to limit or eliminate this effect. For the moment, an intermediate step (wet chemical etching or weak sputtering) is required to obtain a CIGS phase in the crater. Finally, we have demonstrated the possibility to restart the GD-OES analyses of the materials after XPS quantification or GD-OES breaking without modifying the profile shape.

  12. Detergency of stainless steel surface soiled with human brain homogenate: an XPS study

    NASA Astrophysics Data System (ADS)

    Richard, M.; Le Mogne, Th.; Perret-Liaudet, A.; Rauwel, G.; Criquelion, J.; De Barros, M. I.; Cêtre, J. C.; Martin, J. M.

    2005-02-01

    In the detergency field of re-usable medical devices, a special attention is focused on the non conventional transmissible agent called prions which is a proteinaceous infectious agent. Few cleaning procedures are effective against prions and few techniques are available to study cleaning effectiveness with respect to proteins in general. In our study, X-ray photoelectron spectroscopy (XPS) has been used to evaluate the effectiveness of detergent formulations to remove proteins from stainless steel surface soiled with a brain homogenate (BH) from human origin. Our results showed that XPS is a reliable surface analysis technique to study chemical species remaining on surface and substrate properties after cleaning procedures. A semi-quantitative evaluation of the detergency effectiveness could also be performed.

  13. Valence band structure of binary chalcogenide vitreous semiconductors by high-resolution XPS

    SciTech Connect

    Kozyukhin, S.; Golovchak, R.; Kovalskiy, A.; Shpotyuk, O.; Jain, H.

    2011-04-15

    High-resolution X-ray photoelectron spectroscopy (XPS) is used to study regularities in the formation of valence band electronic structure in binary As{sub x}Se{sub 100-x}, As{sub x}S{sub 100-x}, Ge{sub x}Se{sub 100-x} and Ge{sub x}S{sub 100-x} chalcogenide vitreous semiconductors. It is shown that the highest occupied energetic states in the valence band of these materials are formed by lone pair electrons of chalcogen atoms, which play dominant role in the formation of valence band electronic structure of chalcogen-rich glasses. A well-expressed contribution from chalcogen bonding p electrons and more deep s orbitals are also recorded in the experimental valence band XPS spectra. Compositional dependences of the observed bands are qualitatively analyzed from structural and compositional points of view.

  14. Surface and optical analyses of a dye-mineral composite -- an XPS, FTIR and Raman study

    NASA Astrophysics Data System (ADS)

    Durrer, William; Manciu, Felicia; Ramirez, Alejandra; Chianelli, Russell

    2007-10-01

    Maya Purple is a pigment produced by mixing the dye thioindigo with the clay mineral palygorskite. In this investigation, we address the questions of how the dye binds to the clay and how such binding might be affected by the organic-inorganic material ratio and of the heating time used in the preparation of the pigment. Synthetically prepared Maya Purple samples were examined using XPS, FTIR, and Raman spectroscopy. XPS measurements show that pigment preparation results in interactions between the dye and the mineral that give rise to several different binding states of the key elemental components oxygen, sulfur, and aluminum. These results are in good agreement with the Raman analysis, where the appearance and disappearance of bands in the 600 cm-1, 1100 cm-1, and 1600 cm-1 regions demonstrate interaction affecting oxygen and sulfur. The data are further corroborated by vibrational line shifting in the FTIR data.

  15. Toward a better determination of dairy powders surface composition through XPS matrices development.

    PubMed

    Nikolova, Y; Petit, J; Sanders, C; Gianfrancesco, A; Scher, J; Gaiani, C

    2015-01-01

    The surface composition of dairy powders prepared by mixing various amounts of micellar casein (MC), whey proteins isolate (WPI), lactose, and anhydrous milk fat (AMF) was investigated by XPS measurements. The use of matrices are generally accepted to transform surface atomic composition (i.e., C, O, N contents) into surface component composition (i.e., lactose, proteins, lipids). These atomic-based matrices were revisited and two new matrices based on the surface bond composition were developed. Surface compositions obtained from atomic and bond-based matrices were compared. A successful matrix allowing good correlations between XPS predicted and theoretical surface composition for powders free from fat was identified. Nevertheless, samples containing milk fat were found to present a possible segregation of components owing to the AMF overrepresentation on the surface. Supplementary analyses (FTIR, SEM) were carried out in order to investigate the homogeneity of the mixtures. PMID:25460597

  16. Sn-loss effect in a Sn-implanted a-SiO2 host-matrix after thermal annealing: A combined XPS, PL, and DFT study

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Zatsepin, A. F.; Boukhvalov, D. W.; Kurmaev, E. Z.; Gavrilov, N. V.

    2016-03-01

    Amorphous a-SiO2 host-matrices were implanted with Sn-ions with and without posterior thermal tempering at 900 °C for 1 h in ambient air. X-ray photoelectron spectroscopy analysis (XPS core-levels, XPS valence band mapping), photoluminescence (PL) probing, and density functional calculations (DFT) were employed to enable a detailed electronic structure characterization of these samples. It was experimentally established that the process of Sn-embedding into the a-SiO2 host occurs following two dissimilar trends: the Sn4+ → Si4+ substitution in a-SiO2:Sn (without tempering), and Sn-metal clustering as interstitials in a-SiO2:Sn (900 °C, 1 h). Both trends were modeled using calculated formation energies and partial densities of states (PDOS) as well as valence band (VB) simulations, which yielded evidence that substitutional defect generation occurs with the help of ion-implantation stimulated translocation of the host-atoms from their stoichiometric positions to the interstitial void. Experimental and theoretical data obtained coincide in terms of the reported Sn-loss effect in a-SiO2:Sn (900 °C, 1 h) due to thermally-induced electronic host-structure re-arraignment, which manifests as backward host-atoms translocation into stoichiometric positions and the posterior formation of Sn-metal clusters.

  17. SEM and XPS studies of nanohole arrays on InP(1 0 0) surfaces created by coupling AAO templates and low energy Ar + ion sputtering

    NASA Astrophysics Data System (ADS)

    Robert-Goumet, C.; Monier, G.; Zefack, B.; Chelda, S.; Bideux, L.; Gruzza, B.; Awitor, O. K.

    2009-10-01

    The aim of the present study is to demonstrate the feasibility to form well-ordered nanoholes on InP(1 0 0) surfaces by low Ar + ion sputtering process in UHV conditions from anodized aluminum oxide (AAO) templates. This process is a promising approach in creating ordered arrays of surface nanostructures with controllable size and morphology. To follow the Ar + ion sputtering effects on the AAO/InP surfaces, X-ray photoelectron spectroscopy (XPS) was used to determine the different surface species. In 4d and P 2p core level spectra were recorded on different InP(1 0 0) surfaces after ions bombardment. XPS results showed the presence of metallic indium on both smooth InP(1 0 0) and AAO/InP(1 0 0) surfaces. Finally, we showed that this experiment led to the formation of metallic In dropplets about 10 nm in diameter on nanoholes patterned InP surface while the as-received InP(1 0 0) surface generated metallic In about 60 nm in diameter.

  18. Investigation on the upconversion luminescence of Sr3AlO4F:Yb3+, Er3+, Ho3+ phosphors

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Zhai, Zhangyin

    2015-12-01

    To develop new emission-tunable upconversion (UC) phosphors, the Sr3AlO4F:5%Yb3+, xEr3+, yHo3+ (0 ≤ x ≤ 1%, 0 ≤ y ≤ 1%) samples were prepared by conversional solid-state reaction method, and their luminescence properties upon 980 nm excitation were studied. Upon 980 nm excitation, Yb3+-Er3+ codoped Sr3AlO4F shows a predominant emission peak between 645 and 700 nm which is attributed to the 4F9/2-4I15/2 transition of Er3+, and the Er3+ green emissions have been almost quenched. In this case, the yellowish green emitting light is obtained. The possible reason was interpreted by the energy level diagram and the proposed UC mechanism. For Yb3+-Ho3+ codoped Sr3AlO4F, three emissions are observed obviously which are all derived from the Ho3+ ion. The corresponding chromaticity coordinates indicate a red emission has been gained. To realize the tunable emission, the typical Sr3AlO4F:5%Yb3+, 0.2%Er3+, 1%Ho3+ phosphor was developed, and its emission spectrum includes the emission peaks of both Er3+ and Ho3+. Correspondingly, the sample gives a yellow emission.

  19. Nitrogen-doped graphene-decorated LiVPO4F nanocomposite as high-voltage cathode material for rechargeable lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Cui, Kai; Hu, Shuchun; Li, Yongkui

    2016-09-01

    In this study, nitrogen-doped graphene decorated LiVPO4F cathode material is firstly synthesized via a facile method. Well-dispersed LiVPO4F nanoparticles are embedded in nitrogen-doped graphene nanosheets, forming an effective conducting network. The added nitrogen-doped graphene nanosheets greatly enhance the electronic conductivity and Li-ion diffusion of LiVPO4F sample. When tested as cathode material for rechargeable lithium-ion batteries, the hybrid electrode exhibits superior high-rate performance and long-term cycling stability between 3.0 and 4.5 V. It delivers a large discharge capacity of 152.7 mAhg-1 at 0.1 C and shows a capacity retention of 97.8% after 60 cycles. Moreover, a reversible capacity of 90.1 mAhg-1 is maintained even after 500 cycles at a high rate of 20 C. The charge-transfer resistance of LiVPO4F electrode is also reduced in the nitrogen-doped graphene, revealing that its electrode-electrolyte complex reactions take place easily and thus improve the electrochemical performance. The above results provide a facile and effective strategy for the synthesis of LiVPO4F cathode material for high-performance lithium-ion batteries.

  20. Calcination products of gibbsite studied by X-ray diffraction, XPS and solid-state NMR

    SciTech Connect

    Malki, A.; Mekhalif, Z.; Detriche, S.; Fonder, G.; Boumaza, A.; Djelloul, A.

    2014-07-01

    The changes caused by heat treatment of gibbsite powder at 300–1473 K were studied using the X-ray diffraction (XRD), X-ray photoemission (XPS) spectra and {sup 27}Al magic angle spinning nuclear magnetic resonance spectroscopy ({sup 27}Al MAS NMR). XRD analysis indicates that the transformation sequence involves the formation of κ-Al{sub 2}O{sub 3} as an intermediate phase between χ- and α-Al{sub 2}O{sub 3}. The crystallite size of χ-Al{sub 2}O{sub 3} is as small as 10 nm. XPS analysis indicates that the ratio of aluminium atoms to oxygen atoms in χ-Al{sub 2}O{sub 3} and κ-Al{sub 2}O{sub 3} increases, whereas the expected ratio is observed in α-Al{sub 2}O{sub 3}. The percentage of AlO{sub 4} units in the transition aluminas follows the same behaviour as the ratio of Al/O. - Graphical abstract: The percentage of AlO{sub 4} units in transition aluminas follows the same behaviour as the ratio of Al/O. - Highlights: • Calcination products of gibbsite studied by XRD, XPS and solid-state NMR. • The crystallite size of χ-Al{sub 2}O{sub 3} is as small as 10 nm. • The Al/O atomic ratio determined by XPS is larger than 2/3 in χ-Al{sub 2}O{sub 3} and κ-Al{sub 2}O{sub 3}. • The percentage of AlO{sub 4} in the aluminas follows the same behaviour as the Al/O atomic ratio.

  1. Fluorescence, XPS, and TOF-SIMS surface chemical state image analysis of DNA microarrays.

    PubMed

    Lee, Chi-Ying; Harbers, Gregory M; Grainger, David W; Gamble, Lara J; Castner, David G

    2007-08-01

    Performance improvements in DNA-modified surfaces required for microarray and biosensor applications rely on improved capabilities to accurately characterize the chemistry and structure of immobilized DNA molecules on micropatterned surfaces. Recent innovations in imaging X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) now permit more detailed studies of micropatterned surfaces. We have exploited the complementary information provided by imaging XPS and imaging TOF-SIMS to detail the chemical composition, spatial distribution, and hybridization efficiency of amine-terminated single-stranded DNA (ssDNA) bound to commercial polyacrylamide-based, amine-reactive microarray slides, immobilized in both macrospot and microarray diagnostic formats. Combinations of XPS imaging and small spot analysis were used to identify micropatterned DNA spots within printed DNA arrays on slide surfaces and quantify DNA elements within individual microarray spots for determination of probe immobilization and hybridization efficiencies. This represents the first report of imaging XPS of DNA immobilization and hybridization efficiencies for arrays fabricated on commercial microarray slides. Imaging TOF-SIMS provided distinct analytical data on the lateral distribution of DNA within single array microspots before and after target hybridization. Principal component analysis (PCA) applied to TOF-SIMS imaging datasets demonstrated that the combination of these two techniques provides information not readily observable in TOF-SIMS images alone, particularly in identifying species associated with array spot nonuniformities (e.g., "halo" or "donut" effects often observed in fluorescence images). Chemically specific spot images were compared to conventional fluorescence scanned images in microarrays to provide new information on spot-to-spot DNA variations that affect current diagnostic reliability, assay variance, and sensitivity. PMID:17625851

  2. XPS investigation on vacuum thermal desorption of UV/ozone treated GaAs(100) surfaces

    NASA Astrophysics Data System (ADS)

    Cossu, G.; Ingo, G. M.; Mattogno, G.; Padeletti, G.; Proietti, G. M.

    In order to prepare suitable surfaces for molecular beam epitaxy (MBE), sacrificial thin oxide layers on HCl etched GaAs(100) surfaces were grown by both air and UV/ozone exposure. Passive films were subsequently removed by vacuum thermal desorption to achieve surfaces that were smooth and clean on an atomic scale. The evolution of the surface chemical composition, as a function of vacuum desorption temperature, has been studied by means of X-ray photoelectron spectroscopy (XPS). XPS results have evidenced for air and UV/ozone exposed GaAs(100) surfaces a relationship between desorption temperature and surface chemical composition; indeed, the oxide removal is temperature dependent and sequentially selective as follows: As 2O 3. AsO and Ga 2O 3. Furthermore, XPS results have shown that air-grown films have a chemical composition and thermal desorption behaviour different from UV/ozone treated materials. Indeed, these latter have an As 2O 3/Ga 2O 3 and an unoxidized As/Ga ratio close to unity for as grown and thermal treated at 580°C surfaces, respectively. By contrast, air-exposed GaAs(100) materials are Ga 2O 3-enriched and after vacuum thermal desorption treatments have never a stoichiometric composition(As (GaAs)/Ga (GaAs)= 1). Furthermore UV/ozone treated GaAs(100) surfaces subjected to a vacuum thermal treatment at 580°C, have a troublesome organic contamination level below XPS detectability, whereas from air-exposed surfaces, carbon is not completely thermally removable

  3. Plasma bromination of HOPG surfaces: A NEXAFS and synchrotron XPS study

    NASA Astrophysics Data System (ADS)

    Lippitz, Andreas; Friedrich, Jörg F.; Unger, Wolfgang E. S.

    2013-05-01

    Br bonding on plasma brominated graphite surfaces has been studied by using Near Edge X-ray Absorption Fine Structure (NEXAFS) and X-ray Photoelectron Spectroscopy (XPS). Br2 and bromoform were used as plasma gases in an r.f. cw low pressure plasma process. Kr plasma had been used to study separately the physical and chemical plasma etching effects. At early steps of plasma bromination which lead to only small XPS Br surface concentration values a quick decay of aromaticity has been observed. At low Br surface concentration radical or even electrophilic addition of bromine onto sp2 carbon atoms is discussed as the dominating reaction pathway. At higher Br surface concentrations the inherent formation of sp3 defects in the graphene network by chemical etching processes promotes nucleophilic substitution of bromine at sp3 carbons as a competing reaction pathway. Both reaction pathways lead to C-Br species characterized by the same Br 3d XPS binding energy. However more than one Br 3d component in XP spectra has been found at lower Br2 plasma induced Br surface concentrations and complexation of bromine at HOPG is assumed as a third way of interaction with Br2 plasma.

  4. XPS and Raman study of slope-polished Cu(In,Ga)Se2 thin films

    NASA Astrophysics Data System (ADS)

    Beak, Gun Yeol; Jeon, Chan-Wook

    2016-05-01

    The growth of quality Cu(In,Ga)Se2 photovoltaic absorber without secondary phases is very important for improving the solar cell efficiency. Although X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy can identify the secondary phases, they provide insufficient information because of their insufficient resolution and complexity in analysis. In general, normal Raman spectroscopy is better for the analysis of secondary phases. On the other hand, the Raman signal provides information for film depths of less than 300 nm, and the Raman information cannot represent the properties of the entire film. In this regard, the authors introduce a new way of identifying secondary phases in Cu(In,Ga)Se2 films using depth Raman analysis. The as-prepared film was polished using a dimple grinder, which expanded a 2 μm thick film to approximately 1 mm, which is more than sufficient to resolve the depth distribution. Raman analysis indicated that the Cu(In,Ga)Se2 film showed different secondary phases, such as CuIn3Se5, InSe and CuSe, present in different depths of the film, whereas XPS provided complex information about the phases. Overall, the present study emphasizes that the Raman depth profile is more efficient for the identification of secondary phases in Cu(In,Ga)Se2 thin films than XPS and XRD. [Figure not available: see fulltext.

  5. Dynamic XPS measurements of ultrathin polyelectrolyte films containing antibacterial Ag–Cu nanoparticles

    SciTech Connect

    Taner-Camcı, Merve; Suzer, Sefik

    2014-03-15

    Ultrathin films consisting of polyelectrolyte layers prepared by layer-by-layer deposition technique and containing also Ag and Cu nanoparticles exhibit superior antibacterial activity toward Escherichia coli. These films have been investigated with XPS measurements under square wave excitation at two different frequencies, in order to further our understanding about the chemical/physical nature of the nanoparticles. Dubbed as dynamical XPS, such measurements bring out similarities and differences among the surface structures by correlating the binding energy shifts of the corresponding XPS peaks. Accordingly, it is observed that the Cu2p, Ag3d of the metal nanoparticles, and S2p of cysteine, the stabilizer and the capping agent, exhibit similar shifts. On the other hand, the C1s, N1s, and S2p peaks of the polyelectrolyte layers shift differently. This finding leads us the claim that the Ag and Cu atoms are in a nanoalloy structure, capped with cystein, as opposed to phase separated entities.

  6. Multiplet splitting for the XPS of heavy elements: Dependence on oxidation state

    NASA Astrophysics Data System (ADS)

    Bagus, Paul S.; Nelin, Connie J.; Al-Salik, Yahya; Ilton, Eugene S.; Idriss, Hicham

    2016-01-01

    Multiplet splittings in X-ray Photo-electron Spectroscopy, XPS, are a means of distinguishing different open shell occupations, or different oxidation states, in a material being studied. Indeed, especially for 3d transition metal complexes, they have provided fingerprints of the metal oxidation state. The present work provides theoretical and experimental evidence that it may also be possible to use multiplets to characterize the oxidation state of heavy metal, lanthanide and actinide, cations in complexes. However, it is important to make a proper choice of the XPS region to study in order to obtain large multiplet splittings. We identify a low binding energy, BE, peak that had been observed for Ce(III) in CeOx as a high spin coupled multiplet. Furthermore, we show that a low BE feature with reasonable intensity is characteristic of other XPS regions and of other metals. This feature arises from a high spin multiplet and serves as a fingerprint to distinguish closed shell from open shell cations. Evidence is presented that it may also be possible to distinguish different open shell occupations.

  7. Adsorption of Cu(II) on the (0001) plane of mica: A REFLEXAFS and XPS study

    SciTech Connect

    Farquhar, M.L.; England, K.E.R.; Vaughan, D.J.; Charnock, J.M. |

    1996-02-10

    Using reflection extended X-ray absorption fine structure spectroscopy (REFLEXAFS) and X-ray photoelectron spectroscopy (XPS) it has been established that Cu(II) in low concentration in aqueous media can be chemisorbed onto the (0001) surface of muscovite mica. From the XPS studies it is suggested that the Cu species is in a similar bonding environment to the copper in copper hydroxide. A depth profile of the reacted mica surface was also carried out using XPS and this suggests that there had been no diffusion of the Cu into the mica surface. REFLEXAFS studies of the reacted mica surface provided information about shells of O, AlSi, and Cu surrounding a central Cu absorber. The best-fit bond distances are as follows: O{single_bond}Cu, 1.98 {angstrom}; Cu{single_bond}Cu, 2.64 {angstrom}; Al/Si{single_bond}Cu, 3.09 {angstrom}. This provides direct evidence for Cu being bound to the surface at aluminate or silicate groups and suggests that the Cu species adsorbed onto the surface are similar to the copper species found in copper hydroxide, plancheite, and shattuckite. It is proposed that Cu is chemisorbed at atomic imperfections, such as steps and kinks, on the mica surface.

  8. Energy Thresholds of DNA Damage Induced by UV Radiation: An XPS Study.

    PubMed

    Gomes, P J; Ferraria, A M; Botelho do Rego, A M; Hoffmann, S V; Ribeiro, P A; Raposo, M

    2015-04-30

    This work stresses on damage at the molecular level caused by ultraviolet radiation (UV) in the range from 3.5 to 8 eV, deoxyribonucleic acid (DNA) films observed by X-ray photoelectron spectroscopy (XPS). Detailed quantitative XPS analysis, in which all the amounts are relative to sodium-assumed not to be released from the samples, of the carbon, oxygen, and particularly, nitrogen components, reveals that irradiation leads to sugar degradation with CO-based compounds release for energies above 6.9 eV and decrease of nitrogen groups which are not involved in hydrogen bonding at energies above 4.2 eV. Also the phosphate groups are seen to decrease to energies above 4.2 eV. Analysis of XPS spectra allowed to conclude that the damage on bases peripheral nitrogen atoms are following the damage on phosphates. It suggests that very low kinetic energy photoelectrons are ejected from the DNA bases, as a result of UV light induced breaking of the phosphate ester groups which forms a transient anion with resonance formation and whereby most of the nitrogen DNA peripheral groups are removed. The degree of ionization of DNA was observed to increase with radiation energy, indicating that the ionized phosphate groups are kept unchanged. This result was interpreted by the shielding of phosphate groups caused by water molecules hydration near sodium atoms. PMID:25844940

  9. Correction of aspect ratio dependency in deep silicon etch using SF6/C4F8/Ar gas mixture

    NASA Astrophysics Data System (ADS)

    Bates, Robert Lee

    The etch rate of deep features in silicon, such as trenches and vias, can vary significantly with the changing Aspect Ratio (AR) of the feature. Developing a better understanding of the complex volumetric and surface chemistry as well as the etching mechanisms controlling the Aspect Ratio Dependent Etch-rate (ARDE) continues to present research opportunities. Recall that ARDE is generally characterized by small AR features etching at faster rates than large AR features. The main causes of ARDE include Knudsen transport of neutrals into and out of the features as well as ion and neutral loss to the walls due to angular spread in the velocity distribution function and differential charging of insulating microstructures. This work focuses on using a continuous plasma process utilizing a gas mixture of SF6/C4F8/Ar to produce trenches of varying widths and depths. The experimental results were obtained using a Plasma-Therm Versaline processing system. Experiments were performed to show that the etch rate of low AR features can be reduced through the deposition of a passivation layer and thereby allow larger AR features to catch up. It is also possible to invert the ARDE in certain circumstances. We will present the insights we have gained into the ARDE process and the solutions we have tested.

  10. Superspace description of wagnerite-group minerals (Mg,Fe,Mn)2(PO4)(F,OH)

    PubMed Central

    Lazic, Biljana; Armbruster, Thomas; Chopin, Christian; Grew, Edward S.; Baronnet, Alain; Palatinus, Lukas

    2014-01-01

    Reinvestigation of more than 40 samples of minerals belonging to the wagnerite group (Mg, Fe, Mn)2(PO4)(F,OH) from diverse geological environments worldwide, using single-crystal X-ray diffraction analysis, showed that most crystals have incommensurate structures and, as such, are not adequately described with known polytype models (2b), (3b), (5b), (7b) and (9b). Therefore, we present here a unified superspace model for the structural description of periodically and aperiodically modulated wagnerite with the (3+1)-dimensional superspace group C2/c(0β0)s0 based on the average triplite structure with cell parameters a ≃ 12.8, b ≃ 6.4, c ≃ 9.6 Å, β ≃ 117° and the modulation vectors q = β b*. The superspace approach provides a way of simple modelling of the positional and occupational modulation of Mg/Fe and F/OH in wagnerite. This allows direct comparison of crystal properties. PMID:24675594

  11. WATEQ4F - a personal computer Fortran translation of the geochemical model WATEQ2 with revised data base

    USGS Publications Warehouse

    Ball, J.W.; Nordstrom, D.K.; Zachmann, D.W.

    1987-01-01

    A FORTRAN 77 version of the PL/1 computer program for the geochemical model WATEQ2, which computes major and trace element speciation and mineral saturation for natural waters has been developed. The code (WATEQ4F) has been adapted to execute on an IBM PC or compatible microcomputer. Two versions of the code are available, one operating with IBM Professional FORTRAN and an 8087 or 89287 numeric coprocessor, and one which operates without a numeric coprocessor using Microsoft FORTRAN 77. The calculation procedure is identical to WATEQ2, which has been installed on many mainframes and minicomputers. Limited data base revisions include the addition of the following ions: AlHS04(++), BaS04, CaHS04(++), FeHS04(++), NaF, SrC03, and SrHCO3(+). This report provides the reactions and references for the data base revisions, instructions for program operation, and an explanation of the input and output files. Attachments contain sample output from three water analyses used as test cases and the complete FORTRAN source listing. U.S. Geological Survey geochemical simulation program PHREEQE and mass balance program BALANCE also have been adapted to execute on an IBM PC or compatible microcomputer with a numeric coprocessor and the IBM Professional FORTRAN compiler. (Author 's abstract)

  12. A Multi-Scale Study on Silicon-Oxide Etching Processes in C4F8/Ar Plasmas

    NASA Astrophysics Data System (ADS)

    Sui, Jiaxing; Zhang, Saiqian; Liu, Zeng; Yan, Jun; Dai, Zhongling

    2016-06-01

    A multi-scale numerical method coupled with the reactor, sheath and trench model is constructed to simulate dry etching of SiO2 in inductively coupled C4F8 plasmas. Firstly, ion and neutral particle densities in the reactor are decided using the CFD-ACE+ commercial software. Then, the ion energy and angular distributions (IEDs and IADs) are obtained in the sheath model with the sheath boundary conditions provided with CFD-ACE+. Finally, the trench profile evolution is simulated in the trench model. What we principally focus on is the effects of the discharge parameters on the etching results. It is found that the discharge parameters, including discharge pressure, radio-frequency (rf) power, gas mixture ratios, bias voltage and frequency, have synergistic effects on IEDs and IADs on the etched material surface, thus further affecting the trench profiles evolution. supported by National Natural Science Foundation of China (No. 11375040) and the Important National Science & Technology Specific Project of China (No. 2011ZX02403-002)

  13. Control Over the Growth of Titania Nanotubes by Anodisation of TI Foil in NH4F-Containing Electrolyte

    NASA Astrophysics Data System (ADS)

    Lockman, Z.; Sreekantan, Srimala; Ismail, Syahriza

    2009-06-01

    TiO2 nanotubes were produced by anodisation of pure titanium foil in a standard two-electrode bath consisting of either 1 M Na2SO4 or glycerol solution containing 5 wt% NH4F. The effect of anodisation voltage applied to the foil was studied to investigate the possibility of controlling the dimensions of the nanotubes produced. It was found that, in both electrochemical baths the diameter of the nanotubes increases with increasing of the applied voltage. However, in 1 M Na2SO4 there appears to be a maximum voltage at which the nanotubular structure persists. The maximum applied voltage must be less than 30 V. Above this voltage, the nanotubular structure is destroyed leaving an oxide with porous-like morphology. In glycerol bath, the maximum voltage is higher. The length of the nanotubes was also found to be dependent on the voltage. In glycerol, the length of the nanotubes increases from 200 nm to 700 nm as the anodisation voltage was increased from 10 to 30 V.

  14. Atomic layer etching of SiO2 under Ar/ C4F8 plasmas with pulsed bias

    NASA Astrophysics Data System (ADS)

    Zhang, Sai-Qian; Dai, Zhong-Ling; Wang, You-Nian; Plasma Simulation; Experiment Group (PSEG) Team

    2015-09-01

    The purge steps in the atomic layer etching (ALE) reduce the throughput and increase the costs. By elaborately choosing bias pulse waveforms, ALE can be achieved without alternating feedstock gas, although compromises are needed between throughput and precision. In this study, a multi-scale model is used to simulate ALE of SiO2 with a pulsed bias in Ar/C4F8 plasmas. Firstly, a commercial software CFD-ACE + is used to calculate the reactant fluxes towards the substrate in a CCP reactor. The ion bombardment energy and angular distributions at substrate are calculated with a hybrid sheath model, where electric field is got from fluid equations, and the ion-neutral collisions are considered applying the Monte Carlo(MC) method. Then, the reactant transport and surface MC reaction algorithm are coupled in a feature scale model. Influences of bias pulse frequency and duty ratio on atomic precision control are studied. Also, comparisons are made between conventional ALE and pulsed bias etching. Results show that when pulsed bias is used instead of alternating the feedstock gas, we can still achieve certain self-limiting nature in etching, with higher throughput and acceptable loss of precision. Supported by National Natural Science Foundation of China (No. 11375040).

  15. Shock wave study and theoretical modeling of the thermal decomposition of c-C4F8.

    PubMed

    Cobos, C J; Hintzer, K; Sölter, L; Tellbach, E; Thaler, A; Troe, J

    2015-12-28

    The thermal dissociation of octafluorocyclobutane, c-C4F8, was studied in shock waves over the range 1150-2300 K by recording UV absorption signals of CF2. It was found that the primary reaction nearly exclusively produces 2 C2F4 which afterwards decomposes to 4 CF2. A primary reaction leading to CF2 + C3F6 is not detected (an upper limit to the yield of the latter channel was found to be about 10 percent). The temperature range of earlier single pulse shock wave experiments was extended. The reaction was shown to be close to its high pressure limit. Combining high and low temperature results leads to a rate constant for the primary dissociation of k1 = 10(15.97) exp(-310.5 kJ mol(-1)/RT) s(-1) in the range 630-1330 K, over which k1 varies over nearly 14 orders of magnitude. Calculations of the energetics of the reaction pathway and the rate constants support the conclusions from the experiments. Also they shed light on the role of the 1,4-biradical CF2CF2CF2CF2 as an intermediate of the reaction. PMID:26577435

  16. Highly Compact (4F2) and Well Behaved Nano-Pillar Transistor Controlled Resistive Switching Cell for Neuromorphic System Application

    PubMed Central

    Chen, Bing; Wang, Xinpeng; Gao, Bin; Fang, Zheng; Kang, Jinfeng; Liu, Lifeng; Liu, Xiaoyan; Lo, Guo-Qiang; Kwong, Dim-Lee

    2014-01-01

    To simplify the architecture of a neuromorphic system, it is extremely desirable to develop synaptic cells with the capacity of low operation power, high density integration, and well controlled synaptic behaviors. In this study, we develop a resistive switching device (ReRAM)-based synaptic cell, fabricated by the CMOS compatible nano-fabrication technology. The developed synaptic cell consists of one vertical gate-all-around Si nano-pillar transistor (1T) and one transition metal-oxide based resistive switching device (1R) stacked on top of the vertical transistor directly. Thanks to the vertical architecture and excellent controllability on the ON/OFF performance of the nano-pillar transistor, the 1T1R synaptic cell shows excellent characteristics such as extremely high-density integration ability with 4F2 footprint, ultra-low operation current (<2 nA), fast switching speed (<10 ns), multilevel data storage and controllable synaptic switching, which are extremely desirable for simplifying the architecture of neuromorphic system. PMID:25359219

  17. Single-crystal structure and Raman spectroscopy of synthetic titanite analog CaAlSiO4F

    NASA Astrophysics Data System (ADS)

    Krüger, Hannes; Többens, Daniel M.; Tropper, Peter; Haefeker, Udo; Kahlenberg, Volker; Fuchs, Martin R.; Olieric, Vincent; Troitzsch, Ulrike

    2015-10-01

    Synthetic CaAlSiO4F, the Al-F analog of titanite, has been investigated using single-crystal synchrotron diffraction experiments at Beamline X06DA (Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland) and Raman spectroscopy. The presented structural model with 40 parameters was refined against 506 unique reflections to a final R o b s of 0.026 (space group A2/ a, a = 6.9120(11), b = 8.5010(10), c = 6.435(2) Å, β = 114.670(11)°, and Z = 4) and exhibits less distorted coordination polyhedra than earlier models from powder data. Vibrational spectra were calculated in harmonic approximation at the Γ point from fully relaxed energy optimisations of the crystal structure, using 3D-periodic density functional theory with Gaussian basis sets and the software CRYSTAL06. The lattice parameters of the fully relaxed structure were in good agreement with the experimental values, with the calculated values 0.8 ± 0.4 % too large; the monoclinic angle was calculated 0.4° too large. The agreement of the calculated Raman frequencies with the observed ones was very good, with standard deviation ±3 cm-1 and maximum deviations of ±7 cm-1. Furthermore, a detailed discussion of the atomic displacements associated with each Raman mode is given.

  18. Surface chemical and photocatalytic consequences of Ca-doping of BiFeO3 as probed by XPS and H2O2 decomposition studies

    NASA Astrophysics Data System (ADS)

    Zaki, Mohamed I.; Ramadan, Wegdan; Katrib, Ali; Rabee, Abdallah I. M.

    2014-10-01

    Pure and Ca-doped Bi1-xCaxFeO3 samples were prepared with x = 0.0-0.2, adopting a sol-gel method. Previously reported studies performed on similarly composed and prepared samples revealed that Ca-doping, above solubility limit (namely at ≥10%-Ca), results in phase separation and formation of BiFeO3/α(γ)-Fe2O3 nanocomposite particles. Hetero p/n nanojunctions thus established were considered to help separating photo-generated electron-hole pairs and, therefore, explain consequent promotion of photo-Fenton catalytic activity of BiFeO3 towards methylene blue degradation in presence of H2O2 additive. However, the encompassed decomposition of H2O2 was not addressed. To bridge this gap of knowledge, the present investigation was designed to assess Ca-doping-effected surface chemical modifications and gauge its impact on the heterogeneous photo-/thermo-catalytic activity of BiFeO3 towards H2O2 decomposition, by means of X-ray photoelectron spectroscopy (XPS) and H2O2 decomposition gravimetry. XPS results revealed generation of high binding energy Bi 4f and Fe 2p states, as well as enhancement of the surface basicity, upon doping to 10%-Ca. These surface chemical consequences are rendered hardly detectable upon further increase of the dopant magnitude to 20%-Ca. In parallel, the H2O2 decomposition activity of the ferrite, under natural visible light, is enhanced to optimize upon Ca-doping at 10%, and, then, decreased on further doping to 20%. H2O2 decomposition experiments carried out in absence of light indicate that the doping promoting impact is reflected essentially in the photocatalytic activity. Accordingly, the observed surface chemical consequences of Ca-doping are considered to consolidate the p/n nanojunctions consequently established in the material bulk, by retarding recombination of visible light generated electron-hole pairs, thus enhancing the heterogeneous photocatalytic activity of BiFeO3.

  19. Digital confocal microscopy using a virtual 4f-system based on numerical beam propagation for depth measurement without mechanical scanning

    NASA Astrophysics Data System (ADS)

    Goto, Yuta; Okamoto, Atsushi; Toda, Masataka; Kuno, Yasuyuki; Nozawa, Jin; Ogawa, Kazuhisa; Tomita, Akihisa

    2016-08-01

    We propose a digital confocal microscope using a virtual 4f-system based on numerical beam propagation for depth measurement without mechanical scanning. In our technique, the information in the sample target along the depth direction is obtained by defocusing the virtual 4f-system, which consists of two virtual lenses arranged in a computer simulation. The principle of our technique is completely different from that of the mechanical scanning method used in the conventional confocal microscope based on digital holography. By using the virtual 4f-system, the measurement and exposure time can be markedly reduced because multilayered tomographic images are generated using a single measurement. In this study, we tested the virtual depth imaging technique by measuring cover glasses arranged along the depth direction.

  20. Intervalence charge transfer luminescence: Interplay between anomalous and 5d − 4f emissions in Yb-doped fluorite-type crystals

    SciTech Connect

    Barandiarán, Zoila Seijo, Luis

    2014-12-21

    In this paper, we report the existence of intervalence charge transfer (IVCT) luminescence in Yb-doped fluorite-type crystals associated with Yb{sup 2+}–Yb{sup 3+} mixed valence pairs. By means of embedded cluster, wave function theory ab initio calculations, we show that the widely studied, very broad band, anomalous emission of Yb{sup 2+}-doped CaF{sub 2} and SrF{sub 2}, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb{sup 2+}–Yb{sup 3+} mixed valence pairs. The IVCT luminescence is very efficiently excited by a two-photon upconversion mechanism where each photon provokes the same strong 4f{sup 14}–1A{sub 1g}→ 4f{sup 13}({sup 2}F{sub 7/2})5de{sub g}–1T{sub 1u} absorption in the Yb{sup 2+} part of the pair: the first one, from the pair ground state; the second one, from an excited state of the pair whose Yb{sup 3+} moiety is in the higher 4f{sup 13}({sup 2}F{sub 5/2}) multiplet. The Yb{sup 2+}–Yb{sup 3+} → Yb{sup 3+}–Yb{sup 2+} IVCT emission consists of an Yb{sup 2+} 5de{sub g} → Yb{sup 3+} 4f{sub 7/2} charge transfer accompanied by a 4f{sub 7/2} → 4f{sub 5/2} deexcitation within the Yb{sup 2+} 4f{sup 13} subshell: [{sup 2}F{sub 5/2}5de{sub g},{sup 2}F{sub 7/2}] → [{sup 2}F{sub 7/2},4f{sup 14}]. The IVCT vertical transition leaves the oxidized and reduced moieties of the pair after electron transfer very far from their equilibrium structures; this explains the unexpectedly large band width of the emission band and its low peak energy, because the large reorganization energies are subtracted from the normal emission. The IVCT energy diagrams resulting from the quantum mechanical calculations explain the different luminescent properties of Yb-doped CaF{sub 2}, SrF{sub 2}, BaF{sub 2}, and SrCl{sub 2}: the presence of IVCT luminescence in Yb-doped CaF{sub 2} and SrF{sub 2}; its coexistence with regular 5d-4f emission in SrF{sub 2}; its absence in BaF{sub 2} and SrCl{sub 2}; the quenching of

  1. Hyperfine structure constants and isotope shift of the levels of the configuration 4 f 6 5 d 6 s 2 in Eu I

    NASA Astrophysics Data System (ADS)

    Elantkowska, M.; Bernard, A.; Dembczyński, J.; Ruczkowski, J.

    1993-06-01

    The hyperfine structure (hfs) and the isotope shift (IS) of transitions between metastable levels of the configuration 4 f 7 5 d 6 s and levels of the configuration 4 f 6 5 d 6 s 2 of151Eu and153Eu were studied by means of the high resolution laser-atomic-beam technique. New data for the hfs in151Eu and153Eu were obtained as well as new and more accurate for the IS between151Eu and153Eu. The measured hfs constants A and B of the 4 f 6 5 d 6 s 2 configuration allow to perform a parametric analysis using the Sandars and Beck theory. The value of the Sternheimer correction is also disscused.

  2. Bond lengths of 4f{sup 1} and 5d{sup 1} states of Ce{sup 3+} hexahalides

    SciTech Connect

    Barandiaran, Zoila; Edelstein, Norman M.; Ordejon, Belen; Ruiperez, Fernando; Seijo, Luis . E-mail: luis.seijo@uam.es

    2005-02-15

    Ligand and solvent effects on the bond length shift experienced by complexes of lanthanide ions upon 4f->5d excitation, addressed by means of ab initio embedded cluster calculations, are presented on the clusters (CeF{sub 6}){sup 3-}, (CeCl{sub 6}){sup 3-}, and (CeBr{sub 6}){sup 3-}in solid elpasolites, in liquid acetonitrile and in vacuo. Previous predictions of bond length shortening upon 4f->5d(t{sub 2g}) excitation seem to be general and, in particular, chloride and bromide compounds in liquid solution are predicted to be good candidates for excited-state EXAFS measurements of the distortion signs. A quantitative analysis of contributions to the bond length shifts is presented, which shows the importance of ligand field effects and points out insufficiencies in the Judd-Morrison model proposed to account for 4f->5d transitions in crystals.

  3. 24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES ...

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

    24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES FOR A BRASS GATE VALVE BODY MADE ON A CORE BOX, CA. 1950. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  4. Self-assembly of mechanically interlocked and threaded rings: a HREELS and XPS study of thiol-functionalised catenane and rotaxane molecules on Au(111)

    NASA Astrophysics Data System (ADS)

    De Nadaı̈, C.; Whelan, C. M.; Perollier, C.; Clarkson, G.; Leigh, D. A.; Caudano, R.; Rudolf, P.

    2000-05-01

    Thiol-functionalised catenane and rotaxane thin films were investigated in order to understand the self-assembly of such complex molecules on Au(111). Adsorption from the liquid phase at 300 K leads to the formation of overlayers without long-range order, as evidenced by high-resolution electron energy-loss spectroscopy (HREELS). As expected for thiol adsorption, the sulfur 2p binding energies determined by X-ray photoelectron spectroscopy (XPS) are consistent with the formation of thiolate surface intermediates. The properties of these films are explored as a function of annealing. Changes in vibrational spectra such as the emergence of a AuO band and variations in core-level binding energies and intensities reveal molecular rearrangement due to partial desorption. In addition, based on coherent domain sizes estimated by the angular width of the elastic beam intensity, annealing promotes long-range order within the adlayers.

  5. Structure and electrochemistry of NaFePO{sub 4} and Na{sub 2}FePO{sub 4}F cathode materials prepared via mechanochemical route

    SciTech Connect

    Kosova, N.V.; Podugolnikov, V.R.; Devyatkina, E.T.; Slobodyuk, A.B.

    2014-12-15

    Highlights: • Na{sub 2}FePO{sub 4}F is prepared by mechanochemically assisted solid state synthesis. • The crystal and local structure are studied by XRPD, FTIR, Mössbauer, and NMR. • Na{sup +}/Li{sup +} ion exchange is completed with the formation of NaLiFePO{sub 4}F. • The average D{sub Li} (10{sup −15} cm{sup 2} s{sup −1}) is determined from GITT measurements. - Abstract: Nanostructured NaFePO{sub 4} (space group Pmnb) and Na{sub 2}FePO{sub 4}F (space group Pbcn) were prepared by a quick and facile mechanochemically assisted solid state synthesis. Low-crystalline Na{sub 2}FePO{sub 4}F was formed as a result of direct mechanochemical reaction of NaFePO{sub 4} with NaF. It crystallizes upon subsequent heating to 600 °C and decomposes at higher temperatures. Crystal and local structure were analyzed by XRD using Rietveld refinement, FTIR, Mössbauer, and NMR spectroscopy. Electrochemical properties were studied by galvanostatic cycling in lithium cells and GITT. Although NaFePO{sub 4} showed some electrochemical activity, neither electrochemical nor chemical Na{sup +}/Li{sup +} exchange was observed by XRD. On contrary, electrochemical and chemical Na{sup +}/Li{sup +} ion exchange occurred in the case of Na{sub 2}FePO{sub 4}F and accomplished with the NaLiFePO{sub 4}F formation. Li{sup +} diffusion coefficient in NaLiFePO{sub 4}F at different delithiated/lithiated states was determined from GITT. Carbon-coated Na{sub 2}FePO{sub 4}F shows discharge capacity of 116 mA h g{sup −1} at 0.1 C rate within the 2.0–4.2 V voltage range and a good cyclability.

  6. Observation of the surface 4f state of CePd{sub 7} by means of the resonant-inverse-photoemission study at the Ce 4d absorption edge

    SciTech Connect

    Kanai, K.; Tezuka, Y.; Fujisawa, M.; Harada, Y.; Shin, S.; Schmerber, G.; Kappler, J.P.; Parlebas, J.C.; Kotani, A.

    1997-01-01

    The resonant inverse photoemission study (RIPES) of CePd{sub 7}, has been carried out at the Ce 4d{r_arrow}4f absorption edge. The strong resonant enhancement of the 4f cross section enables us to distinguish two 4f components in the empty electronic state near the Fermi level. The incidence-angle dependence of the RIPES indicates a clear difference between ground-state configurations at the bulk and surface. It is found that the former shows a strongly hybridized 4f state, while the latter shows a localized 4f character. The angle dependence of the RIPES of {alpha}-Ce metal has been also carried out and similar results as those of CePd{sub 7} were obtained. The RIPES at the Ce 4d{r_arrow}4f edge is found to be a powerful method to investigate the surface 4f state. {copyright} {ital 1997} {ital The American Physical Society}

  7. A novel oxime-derived 3d-4f single-molecule magnet exhibiting two single-ion magnetic relaxations.

    PubMed

    Dong, Hui-Ming; Li, Yan; Liu, Zhong-Yi; Yang, En-Cui; Zhao, Xiao-Jun

    2016-08-01

    A new oxime-derived {DyNi} cluster with a paramagnetic butterfly-shaped Dy core and peripheral diamagnetic planar-square Ni(II) ions was solvothermally synthesized. The weak ferromagnetically coupled cluster exhibits field-induced single-molecule magnetic behavior with two thermally activated single-ion relaxations. PMID:27377056

  8. Core strengthening.

    PubMed

    Arendt, Elizabeth A

    2007-01-01

    Several recent studies have evaluated interventional techniques designed to reduce the risk of serious knee injuries, particularly noncontact anterior cruciate ligament injuries in female athletes. Maintenance of rotational control of the limb underneath the pelvis, especially in response to cutting and jumping activities, is a common goal in many training programs. Rotational control of the limb underneath the pelvis is mediated by a complex set of factors including the strength of the trunk muscles and the relationship between the core muscles. It is important to examine the interrelationship between lower extremity function and core stability. PMID:17472321

  9. Dodecanuclear 3d/4f-metal clusters with a 'Star of David' topology: single-molecule magnetism and magnetocaloric properties.

    PubMed

    Alexandropoulos, Dimitris I; Cunha-Silva, Luís; Lorusso, Giulia; Evangelisti, Marco; Tang, Jinkui; Stamatatos, Theocharis C

    2016-01-28

    A family of interwoven molecular inorganic knots, shaped like the 'Star of David', was prepared by the employment of naphthalene-2,3-diol in 3d/4f-metal cluster chemistry; the isoskeletal dodecanuclear compounds exhibit slow relaxation of the magnetization and magnetocaloric properties, depending on the metal ion. PMID:26666673

  10. Application of Si and SiO2 Etching Mechanisms in CF4/C4F8/Ar Inductively Coupled Plasmas for Nanoscale Patterns.

    PubMed

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

    2015-10-01

    An investigation of the etching characteristics and mechanism for both Si and SiO2 in CF4/C4F8/Ar inductively coupled plasmas under a constant gas pressure (4 mTorr), total gas flow rate (40 sccm), input power (800 W), and bias power (150 W) was performed. It was found that the variations in the CF4/C4F8 mixing ratio in the range of 0-50% at a constant Ar fraction of 50% resulted in slightly non-monotonic Si and SiO2 etching rates in CF4-rich plasmas and greatly decreasing etching rates in C4F8-rich plasmas. The zero-dimensional plasma model, Langmuir probe diagnostics, and optical emission spectroscopy provided information regarding the formation-decay kinetics for the plasma active species, along with their densities and fluxes. The model-based analysis of the etching kinetics indicated that the non-monotonic etching rates were caused not by the similar behavior of the fluorine atom density but rather by the opposite changes of the fluorine atom flux and ion energy flux. It was also determined that the great decrease in both the Si and SiO2 etching rates during the transition from the CF4/Ar to C4F8/Ar gas system was due to the deposition of the fluorocarbon polymer film. PMID:26726514

  11. High-precision, systematic study of hyperfine structure in the 4f/sup N/6s/sup 2/ configuration of the neutral rare earths

    SciTech Connect

    Childs, W.J.; Goodman, L.S.; Pfeufer, V.

    1983-01-01

    Although the hyperfine structure (hfs) of many-electron atoms has been studied intensively in recent years, it is still difficult to distinguish between the competing effects of relativity and configuration interaction. The 4f/sup N/6s/sup 2/ configuration of the neutral rare earths is of particular interest because (a) the low-lying terms are relatively free of configuration interaction, and (b) trends can be examined systematically as one proceeds through the long 4f-shell. The procedure is to deduce, from the measured hfs constants of low levels, the underlying hyperfine radial integrals for comparison with ab initio predictions. Since some of these integrals are extremely sensitive to any configuration interaction and others are not, it is possible to determine both the extent and type of configuration interaction present in some cases. Prior to the start of the present research no precise hfs information existed for the entire second half of the 4f shell of the rare earths. The present measurements were designed both to provide such data and to make possible a systematic study of the hfs throughout the 4f shell. The atomic-beam, laser-rf, double-resonance method was used for the measurements. With this technique, the occurrence of a radiofrequency transition between atomic hfs levels is detected by noting an increase in the laser-induced fluorescence.

  12. Analysis of the insulation characteristics of c-C4F8 and N2 gas mixtures by Boltzmann equation method

    NASA Astrophysics Data System (ADS)

    Deng, Y. K.; Xiao, D. M.

    2012-02-01

    The present paper concerns itself with the insulation characteristics of c-C4F8/N2 gas mixtures and studies the possibility of applying in the gas insulation of power equipments. We aim to use the theoretical framework of the Boltzmann equation to calculate the density-normalized effective ionization coefficients (α-ƞ)/N and transport parameters of c-C4F8/N2 gas mixtures for E/N values from 180 to 550 Td (1 Td = 10-17 V cm2) in the condition of steady-state Townsend (SST) experiment. From the variation curve of (α-ƞ)/N with the c-C4F8 mixture ratio k, the limiting field strength (E/N)lim of the gas mixtures at different gas content is determined. In order to confirm the validity of the results obtained, comparisons with Monte Carlo simulation and experimental data have been performed. It is found that the insulation properties of c-C4F8 and N2 gas mixtures are much better than those of SF6 and N2 mixtures for applying in the high voltage apparatus as an insulation medium, especially if we take the global warming potential into account.

  13. Repair and Utilization of the Kratos XSAM 800 X-Ray Photoelectron Spectrometer (XPS)

    NASA Technical Reports Server (NTRS)

    Hampton, Michael D.

    2002-01-01

    The objectives for this summer faculty fellowship were first to repair the Kratos XSAM 800 X-ray Photoelectron Spectrometer (XPS) and then to utilize the instrument to participate in ongoing research projects at KSC and in the researcher's own laboratory at UCF. The first 6 weeks were used in repairing the instrument. Working both alone and with the Kratos service engineer, a number of hardware problems, largely associated with the sample stage control system, were corrected. Defective parts were identified and fixed in the computer driver boards, the stage power supply, and the driver interface. The power supply was completely replaced. After four weeks of work, the instrument was functional. This occurred on a Wednesday. The following Friday the instrument had to be completely shut down because the power to the O & C Building was to be turned off. The instrument was properly secured. On Monday, the instrument was powered up and the original problems returned. After another 2 weeks of work, a software problem was identified. This problem caused the computer to use a defective port for the sample stage control. It was circumvented by rewriting the startup routine. The final 3 weeks of the fellowship were spent using the XPS to analyze samples being studied in the Langley materials project (Martha Williams) and a catalyst project (Dr. Orlando Melendez). During this time, several sample analysis requests from other groups at KSC also came in and those samples were run as well. The summer faculty fellowship also allowed many contacts to be made. After meeting with the sensors group, two projects were identified for collaboration and white papers are being prepared. One project aims to develop small, very sensitive hydrogen detectors and the other to develop a broad area, easily monitored, zero power consumption hydrogen detector. In addition to the work mentioned above, the XPS was utilized in a study underway in Dr. Hampton's laboratory at UCF.

  14. Repair and Utilization of the Kratos XSAM 800 X-Ray Photoelectron Spectrometer (XPS)

    NASA Astrophysics Data System (ADS)

    Hampton, Michael D.

    2002-06-01

    The objectives for this summer faculty fellowship were first to repair the Kratos XSAM 800 X-ray Photoelectron Spectrometer (XPS) and then to utilize the instrument to participate in ongoing research projects at KSC and in the researcher's own laboratory at UCF. The first 6 weeks were used in repairing the instrument. Working both alone and with the Kratos service engineer, a number of hardware problems, largely associated with the sample stage control system, were corrected. Defective parts were identified and fixed in the computer driver boards, the stage power supply, and the driver interface. The power supply was completely replaced. After four weeks of work, the instrument was functional. This occurred on a Wednesday. The following Friday the instrument had to be completely shut down because the power to the O & C Building was to be turned off. The instrument was properly secured. On Monday, the instrument was powered up and the original problems returned. After another 2 weeks of work, a software problem was identified. This problem caused the computer to use a defective port for the sample stage control. It was circumvented by rewriting the startup routine. The final 3 weeks of the fellowship were spent using the XPS to analyze samples being studied in the Langley materials project (Martha Williams) and a catalyst project (Dr. Orlando Melendez). During this time, several sample analysis requests from other groups at KSC also came in and those samples were run as well. The summer faculty fellowship also allowed many contacts to be made. After meeting with the sensors group, two projects were identified for collaboration and white papers are being prepared. One project aims to develop small, very sensitive hydrogen detectors and the other to develop a broad area, easily monitored, zero power consumption hydrogen detector. In addition to the work mentioned above, the XPS was utilized in a study underway in Dr. Hampton's laboratory at UCF.

  15. Principal component analysis: a versatile method for processing and investigation of XPS spectra.

    PubMed

    Mc Evoy, Kevin M; Genet, Michel J; Dupont-Gillain, Christine C

    2008-10-01

    Given the relevance of principal component analysis (PCA) to the treatment of spectrometric data, we have evaluated potentialities and limitations of such useful statistical approach for the harvesting of information in large sets of X-ray photoelectron spectroscopy (XPS) spectra. Examples allowed highlighting the contribution of PCA to data treatment by comparing the results of this data analysis with those obtained by the usual XPS quantification methods. PCA was shown to improve the identification of chemical shifts of interest and to reveal correlations between peak components. First attempts to use the method led to poor results, which showed mainly the distance between series of samples analyzed at different moments. To weaken the effect of variations of minor interest, a data normalization strategy was developed and tested. A second issue was encountered with spectra suffering of an even slightly inaccurate binding energy scale correction. Indeed, minor shifts of energy channels lead to the PCA being performed on incorrect variables and consequently to misleading information. In order to improve the energy scale correction and to speed up this step of data pretreatment, a data processing method based on PCA was used. Finally, the overlap of different sources of variation was studied. Since the intensity of a given energy channel consists of electrons from several origins, having suffered inelastic collisions (background) or not (peaks), the PCA approach cannot compare them separately, which may lead to confusion or loss of information. By extracting the peaks from the background and considering them as new variables, the effect of the elemental composition could be taken into account in the case of spectra with very different backgrounds. In conclusion, PCA is a very useful diagnostic tool for the interpretation of XPS spectra, but it requires a careful and appropriate data pretreatment. PMID:18759494

  16. XPS investigation of surface reactivity of electrode materials: effect of the transition metal.

    PubMed

    Andreu, N; Flahaut, D; Dedryvère, R; Minvielle, M; Martinez, H; Gonbeau, D

    2015-04-01

    The role of the transition metal nature and Al2O3 coating on the surface reactivity of LiCoO2 and LiNi(1/3)Mn(1/3)Co(1/3)O2 (NMC) materials were studied by coupling chemisorption of gaseous probes molecules and X-ray photoelectron (XPS) spectroscopy. The XPS analyses have put in evidence the low reactivity of the LiMO2 materials toward basic gaseous probe (NH3). The reactivity toward SO2 gaseous probe is much larger (roughly more than 10 times) and strongly influenced by the nature of metal. Only one adsorption mode (redox process producing adsorbed sulfate species) was observed at the LiCoO2 surface, while NMC materials exhibit sulfate and sulfite species at the surface. On the basis of XPS analysis of bare materials and previous theoretical work, we propose that the acid-base adsorption mode involving the Ni(2+) cation is responsible for the sulfite species on the NMC surface. After Al2O3 coating, the surface reactivity was clearly decreasing for both LiCoO2 and NMC materials. In addition, for LiCoO2, the coating modifies the surface reactivity with the identification of both sulfate and sulfite species. This result is in line with a change in the adsorption mode from redox toward acid-base after Al/Co substitution. In the case of NMC materials, the coating induced a decrease of the sulfite species content at the surface. This phenomenon can be related to the cation mixing effect in the NMC. PMID:25751495

  17. Characterization of antigens adsorbed to anionic PLG microparticles by XPS and TOF-SIMS.

    PubMed

    Chesko, James; Kazzaz, Jina; Ugozzoli, Mildred; Singh, Manmohan; O'Hagan, Derek T; Madden, Claire; Perkins, Mark; Patel, Nikin

    2008-04-01

    The chemical composition of the surface of anionic PLG microparticles before and after adsorption of vaccine antigens was measured using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The interfacial distributions of components will reflect underlying interactions that govern properties such as adsorption, release, and stability of proteins in microparticle vaccine delivery systems. Poly(lactide-co-glycolide) microparticles were prepared by a w/o/w emulsification method in the presence of the anionic surfactant dioctyl sodium sulfosuccinate (DSS). Ovalbumin, lysozyme, a recombinant HIV envelope glyocoprotein and a Neisseria meningitidis B protein were adsorbed to the PLG microparticles, with XPS and time-of-flight secondary mass used to analyze elemental and molecular distributions of components of the surface of lyophilized products. Protein (antigen) binding to PLG microparticles was measured directly by distinct elemental and molecular spectroscopic signatures consistent with amino acids and excipient species. The surface sensitive composition of proteins also included counter ions that support the importance of electrostatic interactions being crucial in the mechanism of adsorptions. The protein binding capacity was consistent with the available surface area and the interpretation of previous electron and atomic force microscope images strengthened by the quantification possible by XPS and the qualitative identification possible with TOF-SIMS. Protein antigens were detected and quantified on the surface of anionic PLG microparticles with varying degrees of efficiency under different adsorption conditions such as surfactant level, pH, and ionic strength. Observable changes in elemental and molecular composition suggest an efficient electrostatic interaction creating a composite surface layer that mediates antigen binding and release. PMID:17724659

  18. Al2O3 e-Beam Evaporated onto Silicon (100)/SiO2, by XPS

    SciTech Connect

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

    2013-09-25

    We report the XPS characterization of a thin film of Al2O3 (35 nm) deposited via e-beam evaporation onto silicon (100). The film was characterized with monochromatic Al Ka radiation. An XPS survey scan, an Al 2p narrow scan, and the valence band spectrum were collected. The Al2O3 thin film is used as a diffusion barrier layer for templated carbon nanotube (CNT) growth in the preparation of microfabricated thin layer chromatography plates.

  19. Five closely related 4-chloro-6,11-dihydro-5H-benzo[b]pyrimido[5,4-f]azepines: similar molecular structures but different supramolecular assemblies.

    PubMed

    Acosta, Lina M; Jurado, Jorge; Palma, Alirio; Cobo, Justo; Glidewell, Christopher

    2015-12-01

    Dibenz[b,f]azepine (DBA) is a privileged 6-7-6 tricyclic ring system of importance in both organic and medicinal chemistry. Benzo[b]pyrimido[5,4-f]azepines (BPAs), which also contain a privileged 6-7-6 ring system, are less well investigated, probably because of a lack of straightforward and versatile methods for their synthesis. A simple and versatile synthetic approach to BPAs based on intramolecular Friedel-Crafts alkylation has been developed. A group of closely-related benzo[b]pyrimido[5,4-f]azepine derivatives, namely (6RS)-4-chloro-6,11-dimethyl-6,11-dihydro-5H-benzo[b]pyrimido[5,4-f]azepine, C14H14ClN3, (I), (6RS)-4-chloro-8-hydroxy-6,11-dimethyl-6,11-dihydro-5H-benzo[b]pyrimido[5,4-f]azepine, C14H14ClN3O, (II), (6RS)-4-chloro-8-methoxy-6,11-dimethyl-6,11-dihydro-5H-benzo[b]pyrimido[5,4-f]azepine, C15H16ClN3O, (III), and (6RS)-4-chloro-8-methoxy-6,11-dimethyl-2-phenyl-6,11-dihydro-5H-benzo[b]pyrimido[5,4-f]azepine, C21H20ClN3O, (IV), has been prepared and their structures compared with the recently published structure [Acosta-Quintero et al. (2015). Eur. J. Org. Chem. pp. 5360-5369] of (6RS)-4-chloro-2,6,8,11-tetramethyl-6,11-dihydro-5H-benzo[b]pyrimido[5,4-f]azepine, (V). All five compounds crystallize as racemic mixtures and they have very similar molecular conformations, with the azepine ring adopting a boat-type conformation in each case, although the orientation of the methoxy substituent in each of (III) and (IV) is different. The supramolecular assemblies in (II) and (IV) depend upon hydrogen bonds of the O-H...N and C-H...π(arene) types, respectively, those in (I) and (V) depend upon π-π stacking interactions involving pairs of pyrimidine rings, and that in (III) depends upon a π-π stacking interaction involving pairs of phenyl rings. Short C-Cl...π(pyrimidine) contacts are present in (I), (II) and (IV) but not in (III) or (V). PMID:26632832

  20. Impact of the CYP4F2 gene polymorphisms on the warfarin maintenance dose: A systematic review and meta-analysis

    PubMed Central

    SUN, XUE; YU, WAN-YING; MA, WAN-LE; HUANG, LI-HUA; YANG, GUO-PING

    2016-01-01

    Warfarin is an oral anticoagulant with significant interpatient variability in dosage. A large number of studies have confirmed that the individual warfarin dose is mainly affected by the cytochrome P450 complex subunit 2C9 and vitamin K epoxide reductase complex subunit 1. However, the association between cytochrome P450 4F2 (CYP4F2) gene polymorphisms and warfarin dosage in the Asian population remains controversial. To investigate the impact of the CYP4F2 polymorphism rs2108622 (p.V433M) on warfarin dose requirement, a systematic review and meta-analysis were conducted. According to the strict inclusion and exclusion criteria set, a comprehensive literature search was performed, and the studies published before August 5, 2015 were searched for in PubMed, EMBASE and the China National Knowledge Infrastructure databases. The references were checked by two independent reviewers. The association between the warfarin maintenance dose and CYP4F2 polymorphism was analyzed. Twenty-two studies were included in the meta-analysis. Compared with the CYP4F2 genotype CC, carriers of the CT and TT genotypes required a 9 [95% confidence interval (CI): 6.0–13.0] and 20% (95% CI, 13.0–27.0) higher warfarin dose, respectively. In the combined analysis, T carriers (CT+TT) required an 11% (95% CI, 8.0–14.0) higher warfarin dose compared to the CC genotype. In addition, there was a 10% (95% CI, 5.0–15.0) higher warfarin dose in TT carriers compared to the CT genotype (all P<0.05). The results of the meta-analysis suggest that the effects of the CYP4F2 polymorphism on individual warfarin dose have a statistically significant difference, and the effect degree is variable in the subgroups. Further studies are expected to explore whether the pharmacogenetics model including the CYP4F2 polymorphism can strengthen the prediction of warfarin dose. PMID:27073641

  1. Crystal-field analysis and Zeeman splittings of energy levels of Nd{sup 3+} (4f{sup 3}) in GaN

    SciTech Connect

    Gruber, John B.; Chandra, Sreerenjini; Sardar, Dhiraj K.; Burdick, Gary W.; Woodward, Nathaniel T.; Dierolf, Volkmar

    2011-08-15

    The crystal-field splitting and Zeeman splitting of energy levels of Nd{sup 3+} (4f{sup 3}) doped into semi-conducting GaN (3.2 eV) grown in the hexagonal (huntite) phase by plasma-assisted molecular beam epitaxy have been modeled using a parameterized Hamiltonian defined to operate within the complete 4f{sup 3} electronic configuration of Nd{sup 3+} substituted for Ga{sup 3+} in the lattice. Zeeman splittings were obtained by applying magnetic fields up to 6.6 T with the fields parallel and perpendicular to the crystallographic c-axis. The experimental energy (Stark) levels were obtained from a recent spectroscopic study on the same samples, where the combined excitation emission spectroscopy (CEES) identified the majority of Nd{sup 3+} ions as replacing Ga{sup 3+} in sites of C{sub 3v} symmetry. The manifolds of Nd{sup 3+} (4f{sup 3}){sup 2S+1}L{sub J} modeled for the crystal-field splitting include the ground state, {sup 4}I{sub 9/2}, and excited states {sup 4}I{sub 11/2}, {sup 4}I{sub 13/2}, {sup 4}F{sub 3/2}, {sup 4}F{sub 5/2}, {sup 2}H{sub 9/2}, {sup 4}F{sub 7/2}, {sup 4}S{sub 3/2}, {sup 4}G{sub 5/2}, and {sup 4}G{sub 7/2}. The energies of 41 experimental Stark levels from these manifolds were modeled through the use of a Monte Carlo method in which independent crystal-field parameters (CFP) were given random starting values and optimized using standard least-squares fitting between calculated and experimental Stark levels. Irreducible representations (irreps) and crystal field quantum numbers ({mu}) were assigned to the energy level states of the {sup 4}I{sub 9/2} and {sup 4}F{sub 3/2} multiplet manifolds based on an analysis of the Zeeman data. This allows determination of which of the competing local minima should be considered to be the physically significant minimum. Using standard least-squares fitting between calculated and experimental Stark levels for Nd{sup 3+} in C{sub 3v} symmetry, we obtain a final standard deviation of 7.01 cm{sup -1} (rms = 5

  2. Chemical Visualization of a GaN p-n junction by XPS.

    PubMed

    Caliskan, Deniz; Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2015-01-01

    We report on an operando XPS investigation of a GaN diode, by recording the Ga2p3/2 peak position under both forward and reverse bias. Areal maps of the peak positions under reverse bias are completely decoupled with respect to doped regions and allow a novel chemical visualization of the p-n junction in a 2-D fashion. Other electrical properties of the device, such as leakage current, resistivity of the domains are also tapped via recording line-scan spectra. Application of a triangular voltage excitation enables probing photoresponse of the device. PMID:26359762

  3. XPS and Raman study of zinc containing silica microparticles loaded with insulin

    NASA Astrophysics Data System (ADS)

    Vanea, E.; Simon, V.

    2013-09-01

    Zinc-silica microparticles obtained by sol-gel method solely or by combining sol-gel chemistry with freeze-drying and spray-drying procedures were explored as potential insulin drug delivery carriers for their improved loading efficiency. Zinc containing silica hosts of different specific surface area and mean pore volume loaded with insulin under similar conditions were investigated by X-ray photoelectron spectroscopy (XPS) and confocal micro-Raman spectroscopy in order to assess the insulin adherence to these matrices and the biologically active state of the insulin after embedding.

  4. An XPS study of the KCl surface oxidation in oxygen glow discharge

    NASA Astrophysics Data System (ADS)

    Stoch, J.; Ladecka, M.

    1988-05-01

    The reaction between the surface of KCl and oxygen in a glow discharge has been studied by X-ray photoemission spectroscopy (XPS). Oxygen glow discharge treatment resulted in the formation of a superoxide, which decomposed under vacuum at room temperature to KO 2 and finally to K 2O. No evidence of KClO 3 or KClO 4 formation has been found. Binding energies of some oxygen species in potassium oxides were determined. The possible role of potassium in K-doped silver catalysts of ethylene epoxidation is discussed.

  5. Alumina supported model Pd Ag catalysts: A combined STM, XPS, TPD and IRAS study

    NASA Astrophysics Data System (ADS)

    Khan, N. A.; Uhl, A.; Shaikhutdinov, S.; Freund, H.-J.

    2006-05-01

    The bimetallic Pd-Ag model catalysts were prepared by physical vapor deposition on thin alumina films. The morphology and structure of the Pd-Ag particles were studied by STM, XPS, and by TPD and IRAS of CO. The results showed the formation of true alloy particles with Ag segregated at the surface. The addition of Ag first suppresses the most strongly bonded CO on threefold hollow sites of Pd. With further increasing Ag coverage, only isolated Pd atoms surrounded by Ag atoms are likely present on the surface. The results on CO adsorption suggest that the model Pd-Ag system mimics the structure of the real Pd-Ag catalysts.

  6. Multiwalled Carbon Nanotube Forest Grown via Chemical Vapor Deposition from Iron Catalyst Nanoparticles, 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

    Carbon nanotubes (CNTs) have unique chemical and physical properties. Herein, we report an XPS analysis of a forest of multiwalled CNTs using monochromatic Al Kα radiation. Survey scans show only one element: carbon. The carbon 1s peak is centered 284.5 eV. The C 1s envelope also shows the expected π → π* shake-up peak at ca. 291 eV. The valence band and carbon KVV Auger signals are presented. When patterned, the CNT forests can be used as a template for subsequent deposition of metal oxides to make thin layer chromatography plates.1-3

  7. Chemical Visualization of a GaN p-n junction by XPS

    PubMed Central

    Caliskan, Deniz; Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2015-01-01

    We report on an operando XPS investigation of a GaN diode, by recording the Ga2p3/2 peak position under both forward and reverse bias. Areal maps of the peak positions under reverse bias are completely decoupled with respect to doped regions and allow a novel chemical visualization of the p-n junction in a 2-D fashion. Other electrical properties of the device, such as leakage current, resistivity of the domains are also tapped via recording line-scan spectra. Application of a triangular voltage excitation enables probing photoresponse of the device. PMID:26359762

  8. Characterization of Mo/C catalysts by XRD, XPS, and TOF-SIMS

    SciTech Connect

    Rondon, S.; Wilkinson, W.R.; Proctor, A.; Houalla, M.; Hercules, D.M.

    1995-11-09

    The objective of this work is to undertake a detailed study of the Mo/C system. This will include (a) study of the adsorption of Mo oxyanions from aqueous solutions of ammonium heptamolybdate onto activated carbon and (b) characterization of a series of Mo/C catalysts obtained by the equilibrium absorption method, using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectroscopy. The structural information thus obtained will be used to evaluate the Mo speciation proposed earlier. 35 refs., 6 figs., 2 tabs.

  9. An investigation of the corrosion of polycrystalline iron by XPS, TMS and CEMS

    NASA Astrophysics Data System (ADS)

    Idczak, K.; Idczak, R.; Konieczny, R.

    2016-06-01

    The room temperature studies of polycrystalline iron exposed to air at various temperatures were performed using: the transmission Mössbauer spectroscopy (TMS), the conversion electron Mössbauer spectroscopy (CEMS) and the X-ray photoelectron spectroscopy (XPS). The unique combination of these techniques allows to determine changes of chemical composition and content of iron oxides simultaneously on the surface region, the 300 nm pre-surface region and the bulk of the samples. The results show that the chemical composition of samples changes significantly and it is strongly dependent on temperature at which the iron sample is exposed to air as well as on investigated region.

  10. Hybridization of XRF/XPS and scatterometry for Cu CMP process control

    NASA Astrophysics Data System (ADS)

    L'Herron, Benoit; Chao, Robin; Kim, Kwanghoon; Lee, Wei Ti; Motoyama, Koichi; Deprospo, Bartlet; Standaert, Theodorus; Gaudiello, John; Goldberg, Cindy

    2015-03-01

    This paper demonstrates the synergy between X-rays techniques and scatterometry, and the benefits to combine the data to improve the accuracy and precision for in-line metrology. Particular example is given to show that the hybridization addresses the challenges of aggressive patterning. In 10nm node back-end-of-line (BEOL) integration, we show that the hybridized data between scatterometry and simultaneous X-Ray Fluorescence (XRF) and X-ray Photoelectron Spectroscopy (XPS) provided the closest dimensional correlation to TEM results compared to the individual technique and CDSEM.

  11. A study of the 42CrMo4 steel surface by quantitative XPS electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Flori, M.; Gruzza, B.; Bideux, L.; Monier, G.; Robert-Goumet, C.

    2008-05-01

    Quantitative X-ray photoelectron spectroscopy was used to characterize the native oxide film formed on 42CrMo4 steel surface by air exposure in normal conditions. In order to determine the thickness and composition of the oxide layer we have used a stacking layer model together with experimental XPS sputtering depth profiling. At a nanoscale study, to obtain quantitative results one must take into account fundamental parameters like the attenuation depth of photoelectrons. We have found that both lepidocrocit (γ-FeOOH) and magnetite (Fe 3O 4) were present and the total thickness of the oxide layer was 16 monolayers.

  12. Effects of feedstock availability on the negative ion behavior in a C{sub 4}F{sub 8} inductively coupled plasma

    SciTech Connect

    Zhao, Shu-Xia; Gao, Fei; Wang, Ya-Ping; Wang, You-Nian; Bogaerts, Annemie

    2015-07-21

    In this paper, the negative ion behavior in a C{sub 4}F{sub 8} inductively coupled plasma (ICP) is investigated using a hybrid model. The model predicts a non-monotonic variation of the total negative ion density with power at low pressure (10–30 mTorr), and this trend agrees well with experiments that were carried out in many fluorocarbon (fc) ICP sources, like C{sub 2}F{sub 6}, CHF{sub 3}, and C{sub 4}F{sub 8}. This behavior is explained by the availability of feedstock C{sub 4}F{sub 8} gas as a source of the negative ions, as well as by the presence of low energy electrons due to vibrational excitation at low power. The maximum of the negative ion density shifts to low power values upon decreasing pressure, because of the more pronounced depletion of C{sub 4}F{sub 8} molecules, and at high pressure (∼50 mTorr), the anion density continuously increases with power, which is similar to fc CCP sources. Furthermore, the negative ion composition is identified in this paper. Our work demonstrates that for a clear understanding of the negative ion behavior in radio frequency C{sub 4}F{sub 8} plasma sources, one needs to take into account many factors, like the attachment characteristics, the anion composition, the spatial profiles, and the reactor configuration. Finally, a detailed comparison of our simulation results with experiments is conducted.

  13. Genetic Variation in POU4F3 and GRHL2 Associated with Noise-Induced Hearing Loss in Chinese Population: A Case-Control Study.

    PubMed

    Xu, Xiangrong; Yang, Qiuyue; Jiao, Jie; He, Lihua; Yu, Shanfa; Wang, Jingjing; Gu, Guizhen; Chen, Guoshun; Zhou, Wenhui; Wu, Hui; Li, Yanhong; Zhang, Huanling

    2016-01-01

    Noise-induced hearing loss (NIHL) is an important occupational disease worldwide resulting from interactions between genetic and environmental factors. The purpose of this study was to examine whether genetic variations in POU4F3 and GRHL2 may influence susceptibility to NIHL in the Chinese population. A matched case-control study was carried out among 293 hearing loss individuals and 293 normal hearing workers drawn from a population of 3790 noise-exposed workers. Ten single-nucleotide polymorphisms (SNPs) in POU4F3 and GRHL2 were selected and genotyped. Logistic regression was performed to analyze the main effects of SNPs and the interactions between noise exposure and SNPs. Moreover, the interactions between predictor haplotypes and noise exposure were also analyzed. Analysis revealed that the CC genotype of rs1981361 in the GRHL2 gene was associated with a higher risk of NIHL (adjusted OR = 1.59; 95% CI: 1.08-2.32, p = 0.018). Additionally, the GG genotype of rs3735715 in the GRHL2 gene was also a risk genotype (adjusted OR = 1.48; 95% CI: 1.01-2.19, p = 0.046). Significant interactions were found between rs3735715, rs1981361 (GRHL2), rs1368402 as well as rs891969 (POU4F3) and noise exposure in the high-level exposure groups. Furthermore, the protective haplotype CA in the POU4F3 gene and the risk haplotype GCCG in the GRHL2 gene were identified combined with noise exposure. These results indicated that GRHL2 might be an NIHL susceptibility gene, but the effect of POU4F3 on NIHL could only be detected when taking noise exposure into account, and their effects were enhanced by higher levels of noise exposure. However, the differences were not significant after the Bonferroni correction was applied. These results should be seen as suggestive. PMID:27271650

  14. Synthesis and characterization of the crystal structure and magnetic properties of the new fluorophosphate LiNaCo[PO4]F.

    PubMed

    Ben Yahia, Hamdi; Shikano, Masahiro; Koike, Shinji; Tatsumi, Kuniaki; Kobayashi, Hironori; Kawaji, Hitoshi; Avdeev, Maxim; Miiller, Wojciech; Ling, Chris D; Liu, Jia; Whangbo, Myung-Hwan

    2012-08-20

    The new compound LiNaCo[PO(4)]F was synthesized by a solid state reaction route, and its crystal structure was determined by single-crystal X-ray diffraction measurements. The magnetic properties of LiNaCo[PO(4)]F were characterized by magnetic susceptibility, specific heat, and neutron powder diffraction measurements and also by density functional calculations. LiNaCo[PO(4)]F crystallizes with orthorhombic symmetry, space group Pnma, with a = 10.9334(6), b = 6.2934(11), c = 11.3556(10) Å, and Z = 8. The structure consists of edge-sharing CoO(4)F(2) octahedra forming CoFO(3) chains running along the b axis. These chains are interlinked by PO(4) tetrahedra forming a three-dimensional framework with the tunnels and the cavities filled by the well-ordered sodium and lithium atoms, respectively. The magnetic susceptibility follows the Curie-Weiss behavior above 60 K with θ = -21 K. The specific heat and magnetization measurements show that LiNaCo[PO(4)]F undergoes a three-dimensional magnetic ordering at T(mag) = 10.2(5) K. The neutron powder diffraction measurements at 3 K show that the spins in each CoFO(3) chain along the b-direction are ferromagnetically coupled, while these FM chains are antiferromagnetically coupled along the a-direction but have a noncollinear arrangement along the c-direction. The noncollinear spin arrangement implies the presence of spin conflict along the c-direction. The observed magnetic structures are well explained by the spin exchange constants determined from density functional calculations. PMID:22857520

  15. Synthesis and characterization of the crystal structure, the magnetic and the electrochemical properties of the new fluorophosphate LiNaFe[PO4]F.

    PubMed

    Ben Yahia, Hamdi; Shikano, Masahiro; Sakaebe, Hikari; Koike, Shinji; Tabuchi, Mitsuharu; Kobayashi, Hironori; Kawaji, Hitoshi; Avdeev, Maxim; Miiller, Wojciech; Ling, Christopher D

    2012-10-14

    The new compound LiNaFe[PO(4)]F was synthesized by a solid state reaction route, and its crystal structure was determined using neutron powder diffraction data. LiNaFe[PO(4)]F was characterized by (57)Fe Mössbauer spectroscopy, magnetic susceptibility, specific heat capacity, and electrochemical measurements. LiNaFe[PO(4)]F crystallizes with orthorhombic symmetry, space group Pnma, with a = 10.9568(6) Å, b = 6.3959(3) Å, c = 11.4400(7) Å, V = 801.7(1) Å(3) and Z = 8. The structure consists of edge-sharing FeO(4)F(2) octahedra forming FeFO(3) chains running along the b axis. These chains are interlinked by PO(4) tetrahedra forming a three-dimensional framework with the tunnels and the cavities filled by the well-ordered sodium and lithium atoms, respectively. The specific heat and magnetization measurements show that LiNaFe[PO(4)]F undergoes a three-dimensional antiferromagnetic ordering at T(N) = 20 K. The neutron powder diffraction measurements at 3 K show that each FeFO(3) chain along the b-direction is ferromagnetic (FM), while these FM chains are antiferromagnetically coupled along the a and c-directions with a non-collinear spin arrangement. The galvanometric cycling showed that without any optimization, one mole of alkali metal is extractable between 1.0 V and 5.0 V vs. Li(+)/Li with a discharge capacity between 135 and 145 mAh g(-1). PMID:22895345

  16. Genetic Variation in POU4F3 and GRHL2 Associated with Noise-Induced Hearing Loss in Chinese Population: A Case-Control Study

    PubMed Central

    Xu, Xiangrong; Yang, Qiuyue; Jiao, Jie; He, Lihua; Yu, Shanfa; Wang, Jingjing; Gu, Guizhen; Chen, Guoshun; Zhou, Wenhui; Wu, Hui; Li, Yanhong; Zhang, Huanling

    2016-01-01

    Noise-induced hearing loss (NIHL) is an important occupational disease worldwide resulting from interactions between genetic and environmental factors. The purpose of this study was to examine whether genetic variations in POU4F3 and GRHL2 may influence susceptibility to NIHL in the Chinese population. A matched case-control study was carried out among 293 hearing loss individuals and 293 normal hearing workers drawn from a population of 3790 noise-exposed workers. Ten single-nucleotide polymorphisms (SNPs) in POU4F3 and GRHL2 were selected and genotyped. Logistic regression was performed to analyze the main effects of SNPs and the interactions between noise exposure and SNPs. Moreover, the interactions between predictor haplotypes and noise exposure were also analyzed. Analysis revealed that the CC genotype of rs1981361 in the GRHL2 gene was associated with a higher risk of NIHL (adjusted OR = 1.59; 95% CI: 1.08–2.32, p = 0.018). Additionally, the GG genotype of rs3735715 in the GRHL2 gene was also a risk genotype (adjusted OR = 1.48; 95% CI: 1.01–2.19, p = 0.046). Significant interactions were found between rs3735715, rs1981361 (GRHL2), rs1368402 as well as rs891969 (POU4F3) and noise exposure in the high-level exposure groups. Furthermore, the protective haplotype CA in the POU4F3 gene and the risk haplotype GCCG in the GRHL2 gene were identified combined with noise exposure. These results indicated that GRHL2 might be an NIHL susceptibility gene, but the effect of POU4F3 on NIHL could only be detected when taking noise exposure into account, and their effects were enhanced by higher levels of noise exposure. However, the differences were not significant after the Bonferroni correction was applied. These results should be seen as suggestive. PMID:27271650

  17. The crystal structure of bøgvadite (Na2SrBa2Al4F20)

    NASA Astrophysics Data System (ADS)

    Balić-Žunić, Tonči

    2014-08-01

    The crystal structure of bøgvadite, Na2SrBa2Al4F20, has been solved and refined to a R1 factor of 4.4 % from single-crystal data (Mo Kα X-ray diffraction, CCD area detector) on a sample from the cryolite deposit at Ivittuut, SW Greenland. Bøgvadite is monoclinic, P21/ n space group, with unit cell parameters a = 7.134(1), b = 19.996(3) and c = 5.3440(8) Å, β = 90.02(1)o. A close proximity of the crystal structure to an orthorhombic symmetry and the presence of the two twin components in a nearly 1:1 ratio suggest that the investigated bøgvadite crystal has originally formed as a high-temperature orthorhombic polymorph which on cooling transformed to the stable low temperature monoclinic structure. The bøgvadite crystal structure has groupings of cation-fluoride coordination polyhedra similar to those found in the crystal structures of the genetically closely associated minerals jarlite and jørgensenite. However, its structure type is different from the latter two. The fluoridoaluminate framework of bøgvadite consists of infinite zig-zag chains of cis-connected AlF6 coordination octahedra. The 1 ∞[AlF5] chains are interconnected by infinite chains of Na-F coordination polyhedra which extend in the same direction. Na is coordinated by nine F atoms if its full surrounding is taken in consideration, but makes significant chemical bonds only to closest five. The chains of AlF6 and NaF9 coordination polyhedra form double layers. In the centre of layers, relatively large voids in the form of pentagonal antiprisms are occupied by Sr atoms which make chemical bonds with the closest six F atoms. Between the SrF10 coordinations in the centre of layers run empty channels. The double layers are interconnected by Ba atoms which are coordinated by eight F atoms and fill the spaces between the layers. Bøgvadite belongs to the group of fluoridoaluminates with infinite chains of cis-connected AlF6 coordination octahedra, alike those found in the crystal structures of Ba-fluoridoaluminates.

  18. The Effect of HF/NH4F Etching on the Morphology of Surface Fractures on Fused Silica

    SciTech Connect

    Wong, L; Suratwala, T; Feit, M D; Miller, P E; Steele, R A

    2008-04-03

    The effects of HF/NH{sub 4}F, wet chemical etching on the morphology of individual surface fractures (indentations, scratches) and of an ensemble of surface fractures (ground surfaces) on fused silica glass has been characterized. For the individual surface fractures, a series of static or dynamic (sliding) Vickers and Brinnell indenters were used to create radial, lateral, Hertzian cone and trailing indentation fractures on a set of polished fused silica substrates which were subsequently etched. After short etch times, the visibility of both surface and subsurface cracks is significantly enhanced when observed by optical microscopy. This is attributed to the removal of the polishing-induced Bielby layer and the increased width of the cracks following etching allowing for greater optical scatter at the fracture interface. The removal of material during etching was found to be isotropic except in areas where the etchant has difficulty penetrating or in areas that exhibit significant plastic deformation/densification. Isolated fractures continue to etch, but will never be completely removed since the bottom and top of the crack both etch at the same rate. The etching behavior of ensembles of closely spaced cracks, such as those produced during grinding, has also been characterized. This was done using a second set of fused silica samples that were ground using either fixed or loose abrasives. The resulting samples were etched and both the etch rate and the morphology of the surfaces were monitored as a function of time. Etching results in the formation of a series of open cracks or cusps, each corresponding to the individual fractures originally on the surface of the substrate. During extended etching, the individual cusps coalesce with one another, providing a means of reducing the depth of subsurface damage and the peak-to-valley roughness. In addition, the material removal rate of the ground surfaces was found to scale with the surface area of the cracks as a

  19. Surface composition XPS analysis of a plasma treated polystyrene: Evolution over long storage periods.

    PubMed

    Ba, Ousmane M; Marmey, Pascal; Anselme, Karine; Duncan, Anthony C; Ponche, Arnaud

    2016-09-01

    A polystyrene surface (PS) was initially treated by cold nitrogen and oxygen plasma in order to incorporate in particular amine and hydroxyl functions, respectively. The evolution of the chemical nature of the surface was further monitored over a long time period (580 days) by chemical assay, XPS and contact angle measurements. Surface density quantification of primary amine groups was performed using three chemical amine assays: 4-nitrobenzaldehyde (4-NBZ), Sulfo succinimidyl 6-[3'(2 pyridyldithio)-pionamido] hexanoate (Sulfo-LC-SPDP) and iminothiolane (ITL). The results showed amine densities were in the range of 2 per square nanometer (comparable to the results described in the literature) after 5min of nitrogen plasma treatment. Over the time period investigated, chemical assays, XPS and contact angles suggest a drastic significant evolution of the chemical nature of the surface within the first two weeks. Beyond that time period and up to almost two years, nitrogen plasma modified substrates exhibits a slow and continuous oxidation whereas oxygen plasma modifed polystyrene surface is chemically stable after two weeks of storage. The latter appeared to "ease of" showing relatively mild changes within the one year period. Our results suggest that it may be preferable to wait for a chemical "stabilization" period of two weeks before subsequent covalent immobilization of proteins onto the surface. The originality of this work resides in the study of the plasma treated surface chemistry evolution over long periods of storage time (580 days) considerably exceeding those described in the literature. PMID:27131091

  20. Rondorfite-type structure — XPS and UV–vis study

    SciTech Connect

    Dulski, M.; Bilewska, K.; Wojtyniak, M.; Szade, J.; Kusz, J.; Nowak, A.; Wrzalik, R.; and others

    2015-10-15

    Highlights: • Structural and spectroscopic characterization of chlorosilicate mineral, rondorfite. • Characterization of main photoemission lines and valence band spectra. • The study of color origin’s using UV–vis spectroscopy. • Analysis of structural changes in context of origin of natural fluorescence. • Discussion of a new application possibilities of analyzed mineral - Abstract: This paper focuses on X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy of two different (green, orange) rondorfite samples. The differences in the sample color originate from various O/Cl ratios. The orange color was found to be related either to the isomorphic substitution of Fe{sup 3+}/Al{sup 3+} for Mg{sup 2+}, the presence of atypical [MgO{sub 4}] tetrahedrons in crystal structure or electronegativity of the sample. The tetrahedron is known to be very prone to accumulation of impurities and substitute atoms. Moreover, the XPS data showed tetrahedrally coordinated Mg{sup 2+} and isomorphic substitution of Al{sup 3+}/Fe{sup 3+} for Mg{sup 2+}, which influences local disordering and the point defects density and distribution. Non-equilibrium chlorine positions inside the crystal cages as well as Ca-Cl bonds have also been found. The XPS measurements as a function of temperature indicate occurrence of a structural transformation at about 770 K which is accompanied by a rotation of silicate tetrahedra within magnesiosilicate pentamer and luminescence disappearance.

  1. XPS and AFM analysis of antifouling PEG interfaces for microfabricated silicon biosensors.

    PubMed

    Sharma, Sadhana; Johnson, Robert W; Desai, Tejal A

    2004-09-15

    In the past two decades, the biological and medical fields have seen great advances in the development of biosensors capable of quantifying biomolecules. Many of these biosensors have micro- and nano-scale features, are fabricated using biochip technology, and use silicon as a base material. The creation of antifouling sensor interfaces is critical to avoid serious consequences that arise due to their contact with biological fluids. To this end, we have created thin PEG interfaces of various grafting densities on silicon using a single-step PEG-silane coupling reaction scheme. Initial PEG concentration (5-50 mM) and coupling time (0.5-24 h) were varied to attain different grafting densities, and different PEG interfaces so created were analyzed using XPS and AFM. Furthermore, all the PEG interfaces were evaluated using XPS and AFM for their antifouling abilities using fibrinogen as the model protein. Results indicated that PEG interfaces created in this investigation are appropriate for biosensors with micro- and nano-scale features, and are efficient in controlling protein fouling. PMID:15308226

  2. XPS study of interface formation of CVD SiO2 on InSb

    NASA Astrophysics Data System (ADS)

    Vasquez, R. P.; Grunthaner, F. J.

    1981-10-01

    The interfacial chemistry of CVD SiO2 films deposited on thin native oxides grown on InSb substrates is examined using X-ray photoemission spectroscopy (XPS) and a relatively benign chemical etching technique for depth profiling. An intensity analysis of XPS spectra is used to derive the compositional structure of the interfaces obtained in the SiO2/native oxide/InSb system. Peak positions in these spectra are used to follow the change in substrate surface potential during the etch sequence, and to establish the chemical nature of the species formed during deposition and subsequent processing. Reaction of the substrate with oxygen resulted in an In-rich native oxide and 1-2 monolayers of excess elemental Sb at the native-oxide/substrate interface, incompletely oxidized silane reduced the native oxide, leaving less than 1 monolayer of elemental In at the SiO2/native oxide interface. Etch removal of this thin In-rich layer leads to a change in the substrate surface potential of 0.06 eV, corresponding to a net increase in positive charge. The results are consistent with simple thermodynamic considerations; they are also compared to previously reported studies of deposited dielectrics on III-V compound semiconductors.

  3. Ti/CeOx(111) interfaces studied by XPS and STM

    NASA Astrophysics Data System (ADS)

    Zhou, Yinghui; Zhou, Jing

    2012-04-01

    Low coverage of Ti was deposited on the well-ordered CeOx(111) (1.5 < x < 2) thin films grown on Ru(0001) by physical vapor deposition at room temperature. The structure and interaction of Ti/ceria interfaces were investigated with X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) techniques under ultrahigh vacuum conditions. XPS data indicate that the deposition of Ti on both oxidized and reduced ceria surfaces causes the partial reduction of Ce from + 4 to + 3 state. Ti is formally in the + 4 state. STM data show the formation of small atomic-like titania features at 300 K, which coalesce to form chain structures upon heating. It is demonstrated in the study that the deposition of Ti can form mixed metal oxides at the interface and modify both electronic and structural properties of the ceria support. The structural study of Ti/ceria interfaces can be a key for understanding the higher catalytic activity of the Ti-CeOx mixed oxide catalysts as compared with the individual pure oxides.

  4. STM and XPS study of CeO2(111) reduction by atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Shahed, Syed Mohammad Fakruddin; Hasegawa, Tomo; Sainoo, Yasuyuki; Watanabe, Yoshihide; Isomura, Noritake; Beniya, Atsushi; Hirata, Hirohito; Komeda, Tadahiro

    2014-10-01

    Reduction of CeO2(111)/Ru(0001) surface by atomic hydrogen was investigated using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). We observed the formation of oxygen vacancy trimers and hydroxyl trimers on the stoichiometric CeO2(111) surface when it was exposed to atomic hydrogen at room temperature. The reaction of an impinging hydrogen atom with a surface oxygen atom yields a hydroxyl species, which diffuse on the surface until stabilized by the formation of OH trimers. The hydrogen atoms were located at atop sites of the oxygen atoms in the topmost surface layer. A reaction between the hopping hydrogen atom and the hydroxyl species yields a water molecule, which is desorbed from the surface leaving an oxygen defect. The oxygen vacancies were also observed as a trimer of vacancies. XPS measurements showed an increase of a reduced Ce and hydroxyl species with an amount of exposed hydrogen atoms. The former was estimated by measuring the ratio of Ce3 +/Ce4 + in the Ce 3d components. Our study shows the formation of hydroxyl trimer species in atomic scale upon atomic hydrogen exposure to CeO2(111) surface which could offer new catalytic activity.

  5. XPS Analysis of Ti6Al4V Oxidation Under UHV Conditions

    NASA Astrophysics Data System (ADS)

    Hierro-Oliva, M.; Gallardo-Moreno, A. M.; González-Martín, M. L.

    2014-12-01

    Oxidation of Ti6Al4V is studied by X-ray photoelectron spectroscopy (XPS). Oxide layer growth was monitored on the Ti6Al4V surface for 24 hours. The surface was previously etched with Ar+ ions under ultra-high vacuum conditions. XPS spectra show that TiO and Ti2O3, together with Al2O3, were the earliest oxides formed. Vanadium, despite being detected in its elementary form in the bulk, was not found in any of its oxidized states. TiO2, directly related to the good performance of Ti6Al4V for biomedical applications, did not contribute significantly to the passive layer at the beginning; nevertheless, it was identified after the oxidation process progressed to a more advanced stage. This behavior indicates that reoxidation of Ti6Al4V permits auto-healing of its passive layer, with the presence of TiO2, even in conditions of low oxygen availability.

  6. XPS Analysis of Ti6Al4V Oxidation Under UHV Conditions

    NASA Astrophysics Data System (ADS)

    Hierro-Oliva, M.; Gallardo-Moreno, A. M.; González-Martín, M. L.

    2014-09-01

    Oxidation of Ti6Al4V is studied by X-ray photoelectron spectroscopy (XPS). Oxide layer growth was monitored on the Ti6Al4V surface for 24 hours. The surface was previously etched with Ar+ ions under ultra-high vacuum conditions. XPS spectra show that TiO and Ti2O3, together with Al2O3, were the earliest oxides formed. Vanadium, despite being detected in its elementary form in the bulk, was not found in any of its oxidized states. TiO2, directly related to the good performance of Ti6Al4V for biomedical applications, did not contribute significantly to the passive layer at the beginning; nevertheless, it was identified after the oxidation process progressed to a more advanced stage. This behavior indicates that reoxidation of Ti6Al4V permits auto-healing of its passive layer, with the presence of TiO2, even in conditions of low oxygen availability.

  7. Formation of Hydroxyl and Water Layers on MgO Films Studied with Ambient Pressure XPS

    SciTech Connect

    Newberg, J.T.; Starr, D.; Yamamoto, S.; Kaya, S.; Kendelewicz, T.; Mysak, E.R.; Porsgaard, S.; Salmeron, M.B.; Brown Jr., G.E.; Nilsson, A.; Bluhm, H.

    2011-01-01

    To understand the interaction of water with MgO(100), a detailed quantitative assessment of the interfacial chemistry is necessary. We have used ambient pressure X-ray photoelectron spectroscopy (XPS) to measure molecular (H{sub 2}O) and dissociative (OH) water adsorption on a 4 monolayer (ML) thick MgO(100)/Ag(100) film under ambient conditions. Since the entire 4 ML metal oxide (Ox) film is probed by XPS, the reaction of the MgO film with water can be quantitatively studied. Using a multilayer model (Model 1) that measures changes in Ox thickness from O 1s (film) and Ag 3d (substrate) spectra, it is shown that the oxide portion of the MgO film becomes thinner upon hydroxylation. A reaction mechanism is postulated in which the top-most layer of MgO converts to Mg(OH)2 upon dissociation of water. Based on this mechanism a second model (Model 2) is developed to calculate Ox and OH thickness changes based on OH/Ox intensity ratios from O 1s spectra measured in situ, with the known initial Ox thickness prior to hydroxylation. Models 1 and 2 are applied to a 0.15 Torr isobar experiment, yielding similar results for H{sub 2}O, OH and Ox thickness changes as a function of relative humidity.

  8. XAS and XPS Characterization of Mercury Binding on Brominated Activated Carbon

    SciTech Connect

    Hutson,N.; Attwood, B.; Scheckel, K.

    2007-01-01

    Brominated powdered activated carbon sorbents have been shown to be quite effective for mercury capture when injected into the flue gas duct at coal-fired power plants and are especially useful when burning Western low-chlorine subbituminous coals. X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) have been used to determine information about the speciation and binding of mercury on two commercially available brominated activated carbons. The results are compared with similar analysis of a conventional (non-halogenated) and chlorinated activated carbon. Both the XAS and XPS results indicate that the mercury, though introduced as elemental vapor, is consistently bound on the carbon in the oxidized form. The conventional and chlorinated activated carbons appeared to contain mercury bound to chlorinated sites and possibly to sulfate species that have been incorporated onto the carbon from adsorbed SO{sub 2}. The mercury-containing brominated sorbents appear to contain mercury bound primarily at bromination sites. The mechanism of capture for the sorbents likely consists of surface-enhanced oxidation of the elemental mercury vapor via interaction with surface-bound halide species with subsequent binding by surface halide or sulfate species.

  9. XAS and XPS characterization of mercury binding on brominated activated carbon

    SciTech Connect

    Nick D. Hutson; Brian C. Attwood; Kirk G. Scheckel

    2007-03-01

    Brominated powdered activated carbon sorbents have been shown to be quite effective for mercury capture when injected into the flue gas duct at coal-fired power plants and are especially useful when burning Western low-chlorine subbituminous coals. X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) have been used to determine information about the speciation and binding of mercury on two commercially available brominated activated carbons. The results are compared with similar analysis of a conventional (non-halogenated) and chlorinated activated carbon. Both the XAS and XPS results indicate that the mercury, though introduced as elemental vapor, is consistently bound on the carbon in the oxidized form. The conventional and chlorinated activated carbons appeared to contain mercury bound to chlorinated sites and possibly to sulfate species that have been incorporated onto the carbon from adsorbed SO{sub 2}. The mercury-containing brominated sorbents appear to contain mercury bound primarily at bromination sites. The mechanism of capture for the sorbents likely consists of surface-enhanced oxidation of the elemental mercury vapor via interaction with surface-bound halide species with subsequent binding by surface halide or sulfate species. 22 refs., 3 figs., 2 tabs.

  10. Erosion Rate Variations during XPS Sputter Depth Profiling of Nanoporous Films

    SciTech Connect

    Gaspar, Dan J.; Engelhard, Mark H.; Henry, Matthew C.; Baer, Donald R.

    2005-04-01

    Sputter depth profiling is commonly used to obtain valuable information regarding the three dimensional distribution of elements within a sample, and is one of the best ways to measure the composition of a buried interface or the uniformity of a thin film. X-ray photoelectron spectroscopy (XPS) is one of the analysis tools often used in conjunction with ion beam erosion to obtain sputter depth profiles. However, to obtain accurate depth information it is often necessary to better understand the sputtering process for a specific materials system. Artifacts such as differential sputtering, varying sputter rates and ion beam-induced chemistry are well known. Here, however, we present evidence from experiments on a porous thin film deposited on a Si wafer that relatively small chemical and/or structural changes in a nanoporous film can affect the rate of erosion measured during sputter depth profiling. Reproducible variations in sputter rate are found with chemical modification leading to compositional changes of the nanoporous thin film. The origin of the sputter rate changes is discussed with the aid of results obtained using Fourier transform infrared spectroscopy, profilometry, nuclear reaction analysis, electron microscopy and XPS-based depth profiling.

  11. Quantification problems in depth profiling of pwr steels using Ar+ ion sputtering and XPS analysis.

    PubMed

    Ignatova, Velislava A; Van Den Berghe, Sven; Van Dyck, Steven; Popok, Vladimir N

    2006-10-01

    The oxide scales of AISI 304 formed in boric acid solutions at 300 degrees C and pH = 4.5 have been studied using X-ray photoelectron spectroscopy (XPS) depth profiling. The present focus is depth profile quantification both in depth and chemical composition on a molecular level. The roughness of the samples is studied by atomic force microscopy before and after sputtering, and the erosion rate is determined by measuring the crater depth with a surface profilometer and vertical scanning interferometry. The resulting roughness (20-30 nm), being an order of magnitude lower than the crater depth (0.2-0.5 microm), allows layer-by-layer profiling, although the ion-induced effects result in an uncertainty of the depth calibration of a factor of 2. The XPS spectrum deconvolution and data evaluation applying target factor analysis allows chemical speciation on a molecular level. The elemental distribution as a function of the sputtering time is obtained, and the formation of two layers is observed-one hydroxide (mainly iron-nickel based) on top and a second one deeper, mainly consisting of iron-chromium oxides. PMID:16984670

  12. Behavior of Supported Palladium Oxide Nanoparticles under Reaction Conditions, Studied with near Ambient Pressure XPS.

    PubMed

    Jürgensen, Astrid; Heutz, Niels; Raschke, Hannes; Merz, Klaus; Hergenröder, Roland

    2015-08-01

    Near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is a promising method to close the "pressure gap", and thus, study the surface composition during heterogeneous reactions in situ. The specialized spectrometers necessary for this analytical technique have recently been adapted to operate with a conventional X-ray source, making it available for routine quantitative analysis in the laboratory. This is shown in the present in situ study of the partial oxidation of 2-propanol catalyzed with PdO nanoparticles supported on TiO2, which was investigated under reaction conditions as a function of gas composition (alcohol-to-oxygen ratio) and temperature. Exposure of the nanoparticles to 2-propanol at 30 °C leads to immediate partial reduction of the PdO, followed by a continuous reduction of the remaining PdO during heating. However, gaseous oxygen inhibits the reduction of PdO below 90 °C, and the oxidation of 2-propanol to carboxylates only occurs in the presence of oxygen above 90 °C. These results support the theory that metallic palladium is the active catalyst material, and they show that environmental conditions affect the nanoparticles and the reaction process significantly. The study also revealed challenges and limitations of this analytical method. Specifically, the intensity and fixed photon energy of a conventional X-ray source limit the spectral resolution and surface sensitivity of lab-based NAP-XPS, which affect precision and accuracy of the quantitative analysis. PMID:26144222

  13. XPS analysis of combustion aerosols for chemical composition, surface chemistry, and carbon chemical state.

    PubMed

    Vander Wal, Randy L; Bryg, Vicky M; Hays, Michael D

    2011-03-15

    Carbonaceous aerosols can vary in elemental content, surface chemistry, and carbon nano-structure. Each of these properties is related to the details of soot formation. Fuel source, combustion process (affecting formation and growth conditions), and postcombustion exhaust where oxidation occurs all contribute to the physical structure and surface chemistry of soot. Traditionally such physical and chemical parameters have been measured separately by various techniques. Presented here is the unified measurement of these characteristics using X-ray photoelectron spectroscopy (XPS). In the present study, XPS is applied to combustion soot collected from a diesel engine (running biodiesel and pump-grade fuels); jet engine; and institutional, plant, and residential oil-fired boilers. Elemental composition is mapped by a survey scan over a broad energy range. Surface chemistry and carbon nanostructure are quantified by deconvolution of high-resolution scans over the C1s region. This combination of parameters forms a distinct matrix of identifiers for the soots from these sources. PMID:21322576

  14. GreenLight 180W XPS photovaporization of the prostate: how I do it.

    PubMed

    Zorn, Kevin C; Liberman, Daniel

    2011-10-01

    , resulting in a higher-powered 532 nm wavelength green light laser while still using the same 70-degree deflecting, side firing, silica fiber delivery system. The HPS offered an 88% more collimated beam and smaller spot size, resulting in much higher irradiance or power density in its 2 predecessors (60W and 80W) with a beam divergence of 8 versus 15 degrees. The primary aim for this upgrade was to reduce lasing time and improve clinical outcomes while demonstrating the same degree of safety for patients. Limitations of the 120W system included treatment of large prostates greater than 80g-100g and increased cost related to fiber devitrification and fracture. In 2011, the 180W-Greenlight XPS system was introduced, not only with increased power setting to vaporize tissue quicker but significant fiber-design changes. Internal cooling, metal-tip cap protection and FiberLife (temperature sensing feedback), better preserve the integrity of the fiber generally producing a 1-fiber per case expectation. Initial personal experience with XPS has provided comparable outcomes related to morbidity, but with the opportunity to perform a more complete and rapid procedure. Published clinical data with the XPS is unfortunately lacking. The objective of this report is to detail our approach and technique for GreenLight XPS drawing on personal experience with both enucleation and vaporization techniques with various laser technologies along with having performed over 500 GreenLight HPS and 100 XPS procedures. In this regard, recommendations for training are also made, which relate to existing users of the 80W and 120W GreenLight laser as well as to new laser users. PMID:22018158

  15. Ar plasma treated and Al metallised polycarbonate: a XPS, mass spectroscopy and SFM study

    NASA Astrophysics Data System (ADS)

    Seidel, C.; Kopf, H.; Gotsmann, B.; Vieth, T.; Fuchs, H.; Reihs, K.

    1999-08-01

    Ar plasma etched and Al metallised bisphenol A carbonate was analysed by mass spectroscopy, photoelectron spectroscopy (XPS), and scanning force microscopy (SFM). We mainly used a technical polymer (Makrolon 2808, Bayer) made by injection-moulding, as well as spin coated bisphenol A carbonate ( n=1) and polycarbonate (PC) ( n=115). The mass spectroscopy during the etching process shows the degradation of the PC in the form of carbon monoxide, carbon dioxide and methyl groups. The photoelectron spectroscopy shows in detail the surface modification after Ar plasma treatment and metallisation. The plasma induces a reduction of the carboxylic carbon (C 1s), a strong reduction of singly bonded oxygen (O 1s) and also a slight reduction of doubly bonded oxygen. After Al metallisation, a reaction of Al with the oxygen groups and an interaction with the aromatic system is documented. Ar plasma etching increases the chemical interaction of Al mainly with the aromatic carbon. The X-ray photoelectron spectroscopy of metallised PC under different initial conditions shows a strong influence of incorporated water in the PC bulk that cannot be seen by XPS on uncoated PC. The O 1s signal increases during metallisation and results in an oxidation of Al probably caused by the fact that the hydrophobic surfaces becomes hydrophillic. Temperature-dependent XPS was done on technical PC samples and on spin coated samples ( n=1, n=115) and supports the influence of the bulk state for the Al-PC interface. For n=1 carbonate, a diffusion of Al into the PC volume was observed. The SFM measurements showed a roughening effect on the nanometer scale even after short treatment times. Al can be seen as a weakly bound cluster on the virgin PC, and if a pre-etching is done, Al seems to grow as a good wetting film. The adhesion force of Al films on PC without any influence of the volume can be explained by the chemical bonding of Al to the carboxylic and aromatic systems. The adhesion can be increased

  16. s-wave threshold in electron attachment - Results in 2-C4F6 and CFCl3 at ultra-low electron energies

    NASA Technical Reports Server (NTRS)

    Chutjian, A.; Alajajian, S. H.; Ajello, J. M.; Orient, O. J.

    1984-01-01

    Electron attachment lineshapes and cross sections are reported for the processes 2-C4F6(-)/2-C4F6 and Cl(-)/CFCl3 at electron energies of 0-120 and 0-140 meV, and at resolutions of 6 and 7 meV (FWHM), respectively. As in previous measurements in CCl4 and SF6, the results show resolution-limited narrow structure in the cross section at electron energies below 15 meV. This structure arises from the divergence of the s-wave cross section in the limit of zero electron energy. Comparisons are given with swarm-measured results, and with collisional ionization (high-Rydberg attachment) data in this energy range.

  17. Electric field effect on the emission rate of H4F and H4S hole traps in InP

    NASA Astrophysics Data System (ADS)

    Darwich, R.; Alek, B.

    2009-05-01

    The electric field effect on the emission rate enhancement of the H4F and H4S hole trap in highly Zn-doped InP has been examined using the deep level transient spectroscopy (DLTS) and double correlation DLTS (DDLTS). The DLTS and DDLTS results have been found to be in good agreement for low and intermediate electric fields, but they disagree for large field effect. Comparing our emission data with the theory, we have found that H4F obeys the quantum model of phonon-assisted tunneling, while H4S follows the Poole-Frenkel model employing a three-dimensional screening Coulombic potential. Our results show that the H4S defect can be attributed to a charged (Vp-Zn ) complex.

  18. Evidence of Eu{sup 2+} 4f electrons in the valence band spectra of EuTiO{sub 3} and EuZrO{sub 3}

    SciTech Connect

    Kolodiazhnyi, T.; Valant, M.; Williams, J. R.; Bugnet, M.; Botton, G. A.; Ohashi, N.; Sakka, Y.

    2012-10-15

    We report on optical band gap and valence electronic structure of two Eu{sup 2+}-based perovskites, EuTiO{sub 3} and EuZrO{sub 3} as revealed by diffuse optical scattering, electron energy loss spectroscopy, and valence-band x-ray photoelectron spectroscopy. The data show good agreement with the first-principles studies in which the top of the valence band structure is formed by the narrow Eu 4f{sup 7} electron band. The O 2p band shows the features similar to those of the Ba(Sr)TiO{sub 3} perovskites except that it is shifted to higher binding energies. Appearance of the Eu{sup 2+} 4f{sup 7} band is a reason for narrowing of the optical band gap in the title compounds as compared to their Sr-based analogues.

  19. 5d-4f emission of Eu2+ and electron-vibrational interaction in several alkaline earth sulfides doped with Eu2+ and Er3+

    NASA Astrophysics Data System (ADS)

    Kumar, G. A.; Liu, D.-X.; Tian, Y.; Brik, M. G.; Sardar, D. K.

    2015-12-01

    Several alkaline earth sulfides doped with Eu2+ and Er3+ ions have been synthesized and shown to be potential phosphors for applications in the visible spectral range. The excitation and emission spectra corresponding to the 4f-5d interconfigurational transitions of Eu2+ were analyzed with an aim of extraction of the main parameters of the electron-vibrational interaction. The values of the Huang-Rhys factor, effective phonon energies, and zero-phonon line positions were systematically compared for all studied materials; physical trends were discussed. As a test for the validity of the obtained parameters, the Eu2+ 5d-4f emission bands were modeled to yield good agreement with the experimental spectra.

  20. Double protein functionalized poly-ε-caprolactone surfaces: in depth ToF-SIMS and XPS characterization.

    PubMed

    Desmet, T; Poleunis, C; Delcorte, A; Dubruel, P

    2012-02-01

    In biomaterial research, great attention has focussed on the immobilization of biomolecules with the aim to increase cell-adhesive properties of materials. Many different strategies can be applied. In previously published work, our group focussed on the treatment of poly-ε-caprolactone (PCL) films by an Ar-plasma, followed by the grafting of 2-aminoethyl methacrylate (AEMA) under UV-irradiation. The functional groups introduced, enabled the subsequent covalent immobilisation of gelatin. The obtained coating was finally applied for the physisorption of fibronectin. The successful PCL surface functionalization was preliminary confirmed using XPS, wettability studies, AFM and SEM. In the present article, we report on an in-depth characterization of the materials developed using ToF-SIMS and XPS analysis. The homogeneous AEMA grafting and the subsequent protein coating steps could be confirmed by both XPS and ToF-SIMS. Using ToF-SIMS, it was possible to demonstrate the presence of polymethacrylates on the surface. From peak deconvoluted XPS results (C- and N-peak), the presence of proteins could be confirmed. Using ToF-SIMS, different positive ions, correlating to specific amino-acids could be identified. Importantly, the gelatin and the fibronectin coatings could be qualitatively distinguished. Interestingly for biomedical applications, ethylene oxide sterilization did not affect the surface chemical composition. This research clearly demonstrates the complementarities of XPS and ToF-SIMS in biomedical surface modification research. PMID:22203514

  1. Final environmental impact statement/report and 4(f) statement. Volume 1. Northeast corridor improvement project electrification: New Haven, CT to Boston, MA. Final report

    SciTech Connect

    1994-10-31

    This document is the final environmental impact statement and final environmental impact report (FEIS/R) on the proposal by the National Railroad Passenger Corporation (Amtrak) to complete the electrification of the Northeast Corridor main line by extending electric traction from New Haven, CT, to Boston, MA. This document (Volume I) is the main body of the FEIS/R and includes a 4(f) Statement on the proposed location of an electrification facility in the Great Swamp Wildlife Management Area.

  2. Experimental determination of the hole capture kinetics of H4F deep trap in electron-irradiated highly doped p-type InP

    NASA Astrophysics Data System (ADS)

    Darwich, R.; Massarani, B.

    2004-07-01

    The hole capture kinetics of the main trap H4F in electron-irradiated p-type InP has been investigated by experimentally determining the exponential and nonexponential parts. The contribution of the slow part of the total kinetics is about 30% in our samples. An indication to a possible capture rate enhancement due to the electric field in the space-charge region is pointed out.

  3. Li{sub 2}B{sub 3}O{sub 4}F{sub 3}, a new lithium-rich fluorooxoborate

    SciTech Connect

    Pilz, Thomas; Nuss, Hanne; Jansen, Martin

    2012-02-15

    The new lithium fluorooxoborate, Li{sub 2}B{sub 3}O{sub 4}F{sub 3}, is obtained by a solid state reaction from LiBO{sub 2} and LiBF{sub 4} at 553 K and crystallizes in the acentric orthorhombic space group P2{sub 1}2{sub 1}2{sub 1} (no. 19) with the cell parameters a=4.8915(9), b=8.734(2), and c=12.301(2) A. Chains of fluorinated boroxine rings along the b axis consists of BO{sub 3} triangles and BO{sub 2}F{sub 2} as well as BO{sub 3}F tetrahedra. Mobile lithium ions are compensating the negative charge of the anionic chain, in which the fourfold coordinated boron atoms bear a negative formal charge. Annealing Li{sub 2}B{sub 3}O{sub 4}F{sub 3} at temperatures above 573 K leads to conversion into Li{sub 2}B{sub 6}O{sub 9}F{sub 2}. The title compound is an ionic conductor with the highest ion conductivity among the hitherto know lithium fluorooxoborates, with conductivities of 1.6 Multiplication-Sign 10{sup -9} and 1.8 Multiplication-Sign 10{sup -8} S cm{sup -1} at 473 and 523 K, respectively. - Graphical abstract: Repetition unit of Li{sub 2}B{sub 3}O{sub 4}F{sub 3}. Highlights: Black-Right-Pointing-Pointer Li{sub 2}B{sub 3}O{sub 4}F{sub 3} is the third member within the family of lithium fluorooxoborates. Black-Right-Pointing-Pointer It shows the highest lithium ion conductivity among them. Black-Right-Pointing-Pointer Chains of interconnected fluorinated boroxine rings run along the b axis. Black-Right-Pointing-Pointer Acentric space group meets the requirement for second harmonic generation.

  4. Feasibility of a 486 nm Fraunhofer laser source based on a 4F(sub 3/2) yields 4I(sub 9/2) neodymium laser

    NASA Astrophysics Data System (ADS)

    Hanson, F. E.; Katz, D. L.; Poirier, P.

    1992-03-01

    The objective of this research was to investigate the potential of a laser source based on the neodymium (4)F(sub 3/2) (yields) (4)I(sub 9/2) transition for operation at 486.1 nm, the H(sub beta) Fraunhofer wavelength. We characterized this transition in Nd:YAG. Also, we identified stimulated rotational Raman conversion in H2, D2, and HD as a critical step in such a system.

  5. Synthesis and electrochemical evolution of mesoporous LiFeSO4F0.56(OH)0.44 with high power and long cyclability.

    PubMed

    Liu, Xiao-Min; Zhang, Su-Long; Yang, Meng; Liao, Xiao-Zhen; Yang, Hui; Shen, Xiao-Dong; Ma, Zi-Feng

    2014-12-14

    A feasible and scalable two-step method is developed to synthesize LiFeSO4F(y)(OH)(1-y) which could deliver 92 and 80 mA h g(-1) when cycled at 1 C and 15 C, respectively. Moreover, with 80% of capacity retention after 2800 cycles at 1 C, this material should be of great interest as a contender to LiFePO4 for use in high power Li-ion batteries. PMID:25347770

  6. Coat protein enhances translational efficiency of Alfalfa mosaic virus RNAs and interacts with the eIF4G component of initiation factor eIF4F.

    PubMed

    Krab, Ivo M; Caldwell, Christian; Gallie, Daniel R; Bol, John F

    2005-06-01

    The three plus-strand genomic RNAs of Alfalfa mosaic virus (AMV) and the subgenomic messenger for viral coat protein (CP) contain a 5'-cap structure, but no 3'-poly(A) tail. Binding of CP to the 3' end of AMV RNAs is required for efficient translation of the viral RNAs and to initiate infection in plant cells. To study the role of CP in translation, plant protoplasts were transfected with luciferase (Luc) transcripts with 3'-terminal sequences consisting of the 3' untranslated region of AMV RNA 3 (Luc-AMV), a poly(A) tail of 50 residues [Luc-poly(A)] or a short vector-derived sequence (Luc-control). Pre-incubation of the transcripts with CP had no effect on Luc expression from Luc-poly(A) or Luc-control, but strongly stimulated Luc expression from Luc-AMV. From time-course experiments, it was calculated that CP binding increased the half-life of Luc-AMV by 20 % and enhanced its translational efficiency by about 40-fold. In addition to the 3' AMV sequence, the cap structure was required for CP-mediated stimulation of Luc-AMV translation. Glutathione S-transferase pull-down assays revealed an interaction between AMV CP and initiation factor complexes eIF4F and eIFiso4F from wheatgerm. Far-Western blotting revealed that this binding occurred through an interaction of CP with the eIF4G and eIFiso4G subunits of eIF4F and eIFiso4F, respectively. The results support the hypothesis that the role of CP in translation of viral RNAs mimics the role of the poly(A)-binding protein in translation of cellular mRNAs. PMID:15914864

  7. High fluence ion beam modification of polymer surfaces: EPR and XPS studies

    NASA Astrophysics Data System (ADS)

    Popok, V. N.; Azarko, I. I.; Odzhaev, V. B.; Tóth, A.; Khaibullin, R. I.

    2001-05-01

    Polyethylene, polyamide-6 and polyimide foils implanted with 100 keV B+, P+ and Sb + ions to a fluence range of 10 15-10 17 cm-2 have been studied using the electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) methods. The experimental data allow the comparison of the implantation-induced changes both in a given polymer foil under different ion beam regimes and in different polymers under similar ion-bombardment conditions. The high fluence implantation of boron ions, depositing energy mainly via electronic stopping, was found to be accompanied with the effective formation of π-bonded carbon-rich clusters. By contrast, heavier (phosphorus and antimony) ions, which deposit energy predominantly in nuclear collisions, produced a lower concentration of π-radicals and a less carbonised top surface layer. The peculiarities and main trends of the alterations of the polymer structure and composition induced via electronic and nuclear stopping have also been discussed.

  8. Study of gadolinia-doped ceria solid electrolyte surface by XPS

    SciTech Connect

    Datta, Pradyot Majewski, Peter; Aldinger, Fritz

    2009-02-15

    Gadolinia-doped ceria (CGO) is an important material to be used as electrolyte for solid oxide fuel cell for intermediate temperature operation. Ceria doped with 10 mol% gadolinia (Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95}) was prepared by conventional solid state synthesis and found to be single phase by room temperature X-ray diffraction (XRD). The chemical states of the surface of the prepared sample were analyzed by X-ray photoelectron spectroscopy (XPS). Though Gd was present in its characteristic chemical state, Ce was found in both Ce{sup 4+} and Ce{sup 3+} states. Presence of Ce{sup 3+} state was ascribed to the differential yield of oxygen atoms in the sputtering process.

  9. XPS study on double glow plasma corrosion-resisting surface alloying layer

    NASA Astrophysics Data System (ADS)

    Ai, Jiahe; Xu, Jiang; He, Fei; Xie, Xishan; Xu, Zhong

    2003-02-01

    Double glow plasma corrosion-resisting surface alloying layer (SAL) formed on low carbon steel 1020 was studied by X-ray photoelectron spectroscopy (XPS) and other means. Results show that the passive film of the surface alloying layer after electrochemical test in 3.5% NaCl solution consists of Cr and Fe oxide such as CrO 3, Cr 2O 3, Fe 2O 3 and FeO and metallic Ni and Mo, and it attributes to the fact that a continuous and compact corrosion-resisting surface alloying layer with rich Cr, Ni and Mo was formed on the surface of steel 1020 so as to increase its corrosion resistance greatly. Therefore, double glow plasma technique will be widely used in corrosion-resisting surface science.

  10. Study by XPS of different conditioning processes to improve the cation exchange in clinoptilolite

    NASA Astrophysics Data System (ADS)

    Ruiz-Serrano, D.; Flores-Acosta, M.; Conde-Barajas, E.; Ramírez-Rosales, D.; Yáñez-Limón, J. M.; Ramírez-Bon, R.

    2010-09-01

    We report the X-ray photoelectron spectroscopy (XPS) analysis of natural clinoptilolite from a mine in Sonora, México. From these measurements we determined the chemical state and binding energy of the elements in the zeolite framework and of those in the extra framework sites. The analysis was done on natural clinoptilolite and on cation-exchanged clinoptilolites with Na + and NH4+ ions. Complementary analysis by several experimental techniques was performed to determine the structural, chemical composition and chemical state modifications experimented by clinoptilolite samples processed by the two types of cation exchange. The clinoptilolite samples were studied by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) to determine their structural composition, Energy Dispersive Spectroscopy (EDS) to measure the chemical composition and electronic paramagnetic resonance (EPR) spectroscopy to determine the chemical state of iron inside the natural zeolites.

  11. Interfacial analysis of tribological systems containing molybdenum disulfide and iron using XPS and CEMS

    NASA Technical Reports Server (NTRS)

    Zabinski, J. S.; George, T.; Tatarchuk, B. J.

    1989-01-01

    In the present evaluation of results from studies of the interfacial chemistry and morphology of a buried lubricant-substrate interface, specimens of increasing complexity that culminated with the effects of excess sulfur and defects were characterized by XPS and SEM, as well as conversion-electron Moessbauer spectroscopy (CEMS). In order to simulate sputtered systems, single crystals of MoS2 were damaged with Ar(+) bombardment and coated with Fe. Fe is found to react differently with MoS2 depending on surface treatments, surface defects, annealing treatments, and the presence of excess sulfur. The annealing temperature determines which compounds are formed, as well as the crystal habit and plane at the Fe-MoS2 interface.

  12. Use of XPS to investigate surface problems in ULC deep drawing steels

    NASA Astrophysics Data System (ADS)

    Lamberigts, Marcel; Servais, Jean-Pierre

    1999-04-01

    During continuous annealing prior to hot dip galvanising, the surface of ULC ( Ultra Low Carbon) deep drawing steels undergoes a range of chemical modifications that can affect interface reactions, thus influencing the quality of the metallic protective coating and the product's final user's properties. These phenomena were investigated by XPS, in a high-resolution, fully automatic spectrometer coupled with a tight preparation chamber, where the treatment can be simulated very faithfully, in terms of both heat cycle and protective atmosphere. Under vacuum, the equilibrium (Gibbs) surface segregation of alloying — or tramp — elements such as P, Sn, Sb, As, S and C is clearly the predominant phenomenon. Selective oxidation grows much more significant when annealing is performed under a water vapour containing N 2-5%H 2 protective atmosphere. It involves highly oxidisable elements such as Al, Mn and Si. Though much less intense than under vacuum, Gibbs segregation however remains present, in direct competition with selective oxidation.

  13. The impact of quadrupole moment of 4f shell on the hyperfine interactions anisotropy in RAl2 (R=Sm, Tb) intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Delyagin, N. N.; Erzinkyan, A. L.

    2016-03-01

    The magnetic hyperfine interactions for 119Sn impurity atoms in SmAl2 and TbAl2 ferromagnetic compounds have been investigated by Mössbauer spectroscopy technique. These compounds have the same structure but differ in the sign of the quadrupole moment of the R3+ ion. In both cases, the spectrum contains two magnetic subspectra with the ratio of the intensities 1:3, which correspond to a and b Al sites with significantly different hyperfine parameters. The phenomenon change the order the component of inversion component of the Mössbauer spectra was found. This phenomenon is explained by the influence of the quadrupole moment 4f-shell of R3+ ions on the electron density distribution in the valence band. The degree of overlap of electron wave functions being on hybrid orbitals greatly depends on the sign of the 4f-shell quadrupole moment, which gives rise to huge anisotropy in the hyperfine magnetic field and the electric field gradient. Quadrupole deformation induced by the 4f quadrupole moment and the electric field gradient, greatly affects the d-like and p-like components of the electron wave functions, but little effect on the its s-components.

  14. Configuration-averaged 4f orbitals in ab initio calculations of low-lying crystal field levels in lanthanide(iii) complexes.

    PubMed

    Van den Heuvel, Willem; Calvello, Simone; Soncini, Alessandro

    2016-06-21

    A successful and commonly used ab initio method for the calculation of crystal field levels and magnetic anisotropy of lanthanide complexes consists of spin-adapted state-averaged CASSCF calculations followed by state interaction with spin-orbit coupling (SI-SO). Based on two observations valid for Ln(iii) complexes, namely: (i) CASSCF 4f orbitals are expected to change very little when optimized for different states belonging to the 4f electronic configuration, (ii) due to strong spin-orbit coupling the total spin is not a good quantum number, we show here via a straightforward analysis and direct calculation that the CASSCF/SI-SO method can be simplified to a single configuration-averaged HF calculation and one complete active space CI diagonalization, including spin-orbit coupling, on determinant basis. Besides its conceptual simplicity, this approach has the advantage that all spin states of the 4f(n) configuration are automatically included in the SO coupling, thereby overcoming one of the computational limitations of the existing CASSCF/SI-SO approach. As an example, we consider three isostructural complexes [Ln(acac)3(H2O)2], Ln = Dy(3+), Ho(3+), Er(3+), and find that the proposed simplified method yields crystal field levels and magnetic g-tensors that are in very good agreement with those obtained with CASSCF/SI-SO. PMID:27231024

  15. Fluorocarbon assisted atomic layer etching of SiO2 and Si using cyclic Ar/C4F8 and Ar/CHF3 plasma

    DOE PAGESBeta

    Metzler, Dominik; Li, Chen; Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A.; Oehrlein, Gottlieb S.

    2015-11-11

    The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C4F8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C4F8 injection and synchronized plasma-based low energy Ar+ ion bombardment has been established for SiO2.1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF3 as a precursor is examined and compared to C4F8. CHF3 is shown to enable selective SiO2/Si etching using a fluorocarbon (FC) film build up. Othermore » critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less

  16. The liquid-vapor equilibria of TIP4P/2005 and BLYPSP-4F water models determined through direct simulations of the liquid-vapor interface.

    PubMed

    Hu, Hongyi; Wang, Feng

    2015-06-01

    In this paper, the surface tension and critical properties for the TIP4P/2005 and BLYPSP-4F models are reported. A clear dependence of surface tension on the van der Waals cutoff radius (rvdw) is shown when van der Waals interactions are modeled with a simple cutoff scheme. A linear extrapolation formula is proposed that can be used to determine the infinite rvdw surface tension through a few simulations with finite rvdw. A procedure for determining liquid and vapor densities is proposed that does not require fitting to a profile function. Although the critical temperature of water is also found to depend on the choice of rvdw, the dependence is weaker. We argue that a rvdw of 1.75 nm is a good compromise for water simulations when long-range van der Waals correction is not applied. Since the majority of computational programs do not support rigorous treatment of long-range dispersion, the establishment of a minimal acceptable rvdw is important for the simulation of a variety of inhomogeneous systems, such as water bubbles, and water in confined environments. The BLYPSP-4F model predicts room temperature surface tension marginally better than TIP4P/2005 but overestimates the critical temperature. This is expected since only liquid configurations were fit during the development of the BLYPSP-4F potential. The potential is expected to underestimate the stability of vapor and thus overestimate the region of stability for the liquid. PMID:26049508

  17. Synthesis and tunable luminescent properties of Eu-doped Ca2NaSiO4F - Coexistence of the Eu2+ and Eu3+ centers

    NASA Astrophysics Data System (ADS)

    Xie, Mubiao; Li, Dongyu; Zhu, Guoxian; Pan, Rongkai; Fu, Xionghui

    Novel phosphors Ca2NaSiO4F:Eu were synthesized successfully by the conventional solid-state method in CO atmosphere, and their spectroscopic properties in UV-vis region were investigated. The photoluminescence properties show that Eu3+ ions were partially reduced to Eu2+ in Ca2NaSiO4F. As a result of radiation and re-absorption energy transfer from Eu2+ to Eu3+, both Eu2+ bluish-green emission at around 520 nm and Eu3+ red emission are observed in the emission spectra under the n-UV light excitation. Furthermore, the ratio between Eu2+ and Eu3+ emissions varies with increasing content of overall Eu. Because relative intensity of the red component from Eu3+ became systematically stronger, white light emission can be realized by combining the emission of Eu2+ and Eu3+ in a single host lattice under n-UV light excitation. These results indicate that the Ca2NaSiO4F:Eu phosphors have potential applications as a n-UV convertible phosphor for light-emitting diodes.

  18. Interconfigurational 5d → 4f luminescence of Ce3+ and Pr3+ in Ca9Lu(PO4)7.

    PubMed

    Trevisani, M; Ivanovskikh, K V; Piccinelli, F; Speghini, A; Bettinelli, M

    2012-09-26

    Ca(9)Lu(PO(4))(7):Ce (3+) and Ca (9)Lu (PO (4))(7):Pr (3+) polycrystalline materials were synthesized by solid state reaction at high temperature. The materials were characterized by powder x-ray diffraction (XRPD). The luminescence spectroscopy and the excited state dynamics of these compounds were investigated upon excitation with UV/VUV synchrotron radiation. Both materials showed efficient and fast 5d-4f emission upon direct VUV excitation into the 5d levels but only Ca(9)Lu(PO(4))(7):Ce (3+) revealed luminescence upon excitation across the bandgap. The decay kinetics of the 5d-4f emission upon VUV intra-center excitation is characterized by a decay time of 29 ns for Ce (3+) and 17 ns for Pr (3+) with no significant build-up after the excitation pulse. For the both compounds, no significant temperature dependence of the 5d-4f emission lifetime was observed within the range 8-300 K. PMID:22944734

  19. Impact of the CYP4F2 p.V433M Polymorphism on Coumarin Dose Requirement: Systematic Review and Meta-Analysis

    PubMed Central

    Danese, E; Montagnana, M; Johnson, JA; Rettie, AE; Zambon, CF; Lubitz, SA; Suarez-Kurtz, G; Cavallari, LH; Zhao, L; Huang, M; Nakamura, Y; Mushiroda, T; Kringen, MK; Borgiani, P; Ciccacci, C; Au, NT; Langaee, T; Siguret, V; Loriot, MA; Sagreiya, H; Altman, RB; Shahin, MHA; Scott, SA; Khalifa, SI; Chowbay, B; Suriapranata, IM; Teichert, M; Stricker, BH; Taljaard, M; Botton, MR; Zhang, JE; Pirmohamed, M; Zhang, X; Carlquist, JF; Horne, BD; Lee, MTM; Pengo, V; Guidi, GC; Minuz, P; Fava, C

    2013-01-01

    A systematic review and a meta-analysis were performed to quantify the accumulated information from genetic association studies investigating the impact of the CYP4F2 rs2108622 (p.V433M) polymorphism on coumarin dose requirement. An additional aim was to explore the contribution of the CYP4F2 variant in comparison with, as well as after stratification for, the VKORC1 and CYP2C9 variants. Thirty studies involving 9,470 participants met prespecified inclusion criteria. As compared with CC-homozygotes, T-allele carriers required an 8.3% (95% confidence interval (CI): 5.6–11.1%; P < 0.0001) higher mean daily coumarin dose than CC homozygotes to reach a stable international normalized ratio (INR). There was no evidence of publication bias. Heterogeneity among studies was present (I2 = 43%). Our results show that the CYP4F2 p.V433M polymorphism is associated with interindividual variability in response to coumarin drugs, but with a low effect size that is confirmed to be lower than those contributed by VKORC1 and CYP2C9 polymorphisms. PMID:23132553

  20. An epigenetic biomarker combination of PCDH17 and POU4F2 detects bladder cancer accurately by methylation analyses of urine sediment DNA in Han Chinese

    PubMed Central

    Li, Qiaoling; An, Dan; Fang, Lu; Lin, Youcheng; Hou, Yong; Xu, Abai; Fu, Yu; Lu, Wei; Chen, Xin; Chen, Mingwei; Zhang, Meng; Jiang, Huiling; Zhang, Chuanxia; Dong, Pei; Li, Chong; Chen, Jun; Yang, Guosheng; Liu, Chunxiao; Cai, Zhiming; Zhou, Fangjian; Wu, Song

    2016-01-01

    To develop a routine and effectual procedure of detecting bladder cancer (BlCa), an optimized combination of epigenetic biomarkers that work synergistically with high sensitivity and specificity is necessary. In this study, methylation levels of seven biomarkers (EOMES, GDF15, NID2, PCDH17, POU4F2, TCF21, and ZNF154) in 148 individuals—which including 58 urothelial cell carcinoma (UCC) patients, 20 infected urinary calculi (IUC) patients, 20 kidney cancer (KC) patients,20 prostate cancer (PC) patients, and 30 healthy volunteers (HV)—were quantified by qMSP using the urine sediment DNA. Receiver operating characteristic (ROC) curves were generated for each biomarker. The combining predictors of possible combinations were calculated through logistic regression model. Subsequently, ROC curves of the three best performing combinations were constructed. Then, we validated the three best performing combinations and POU4F2 in another 72 UCC, 21 IUC, 26 KC and 22 PC, and 23 HV urine samples. The combination of POU4F2/PCDH17 has yielded the highest sensitivity and specificity of 90.00% and 93.96% in all the 312 individuals, showing the capability of detecting BlCa effectively among pathologically varied sample groups. PMID:26700620

  1. Colloidal diatomite, radionickel, and humic substance interaction: a combined batch, XPS, and EXAFS investigation.

    PubMed

    Sheng, Guodong; Shen, Runpu; Dong, Huaping; Li, Yimin

    2013-06-01

    This work determined the influence of humic acid (HA) and fulvic acid (FA) on the interaction mechanism and microstructure of Ni(II) onto diatomite by using batch experiments, X-ray photoelectron spectroscopy (XPS), and extended X-ray absorption fine structure (EXAFS) methods. Macroscopic and spectroscopic experiments have been combined to see the evolution of the interaction mechanism and microstructure of Ni(II) in the presence of HA/FA as compared with that in the absence of HA/FA. The results indicated that the interaction of Ni(II) with diatomite presents the expected solution pH edge at 7.0, which is modified by addition of HA/FA. In the presence of HA/FA, the interaction of Ni(II) with diatomite increased below solution pH 7.0, while Ni(II) interaction decreased above solution pH 7.0. XPS analysis suggested that the enrichment of Ni(II) onto diatomite may be due to the formation of (≡SO)2Ni. EXAFS results showed that binary surface complexes and ternary surface complexes of Ni(II) can be simultaneously formed in the presence of HA/FA, whereas only binary surface complexes of Ni(II) are formed in the absence of HA/FA, which contribute to the enhanced Ni(II) uptake at low pH values. The results observed in this work are important for the evaluation of Ni(II) and related radionuclide physicochemical behavior in the natural soil and water environment. PMID:23143822

  2. Arsenopyrite and pyrite bioleaching: evidence from XPS, XRD and ICP techniques.

    PubMed

    Fantauzzi, Marzia; Licheri, Cristina; Atzei, Davide; Loi, Giovanni; Elsener, Bernhard; Rossi, Giovanni; Rossi, Antonella

    2011-10-01

    In this work, a multi-technical bulk and surface analytical approach was used to investigate the bioleaching of a pyrite and arsenopyrite flotation concentrate with a mixed microflora mainly consisting of Acidithiobacillus ferrooxidans. X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and X-ray-induced Auger electron spectroscopy mineral surfaces investigations, along with inductively coupled plasma-atomic emission spectroscopy and carbon, hydrogen, nitrogen and sulphur determination (CHNS) analyses, were carried out prior and after bioleaching. The flotation concentrate was a mixture of pyrite (FeS(2)) and arsenopyrite (FeAsS); after bioleaching, 95% of the initial content of pyrite and 85% of arsenopyrite were dissolved. The chemical state of the main elements (Fe, As and S) at the surface of the bioreactor feed particles and of the residue after bioleaching was investigated by X-ray photoelectron and X-ray excited Auger electron spectroscopy. After bioleaching, no signals of iron, arsenic and sulphur originating from pyrite and arsenopyrite were detected, confirming a strong oxidation and the dissolution of the particles. On the surfaces of the mineral residue particles, elemental sulphur as reaction intermediate of the leaching process and precipitated secondary phases (Fe-OOH and jarosite), together with adsorbed arsenates, was detected. Evidence of microbial cells adhesion at mineral surfaces was also produced: carbon and nitrogen were revealed by CHNS, and nitrogen was also detected on the bioleached surfaces by XPS. This was attributed to the deposition, on the mineral surfaces, of the remnants of a bio-film consisting of an extra-cellular polymer layer that had favoured the bacterial action. PMID:21847529

  3. The influence of surface chemistry on GSR particles: using XPS to complement SEM/EDS analytical techniques

    NASA Astrophysics Data System (ADS)

    Schwoeble, A. J.; Strohmeier, Brian R.; Piasecki, John D.

    2010-06-01

    Gunshot residue particles (GSR) were examined using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) to illustrate the size, shape, morphology, and elemental composition normally observed in particulate resulting from a discharged firearm. Determining the presence of lead (Pb), antimony (Sb), and barium (Ba), barring other elemental tags, fused together in a single particle with the correct morphology, is all that is required for the positive identification of GSR. X-ray photoelectron spectroscopy (XPS), however, can reveal more detailed information on surface chemistry than SEM/EDS. XPS is a highly surface-sensitive (<= ~10 nm), non-destructive, analytical technique that provides qualitative information for all elements except hydrogen and helium. Nanometer-scale sampling depth and its ability to provide unique chemical state information make XPS a potential technique for providing important knowledge on the surface chemistry of GSR that complements results obtained from SEM/EDS analysis.

  4. Atmospheric histories and growth trends of C4F10, C5F12, C6F14, C7F16 and C8F18

    NASA Astrophysics Data System (ADS)

    Ivy, D. J.; Arnold, T.; Harth, C. M.; Steele, L. P.; Mühle, J.; Rigby, M.; Salameh, P. K.; Leist, M.; Krummel, P. B.; Fraser, P. J.; Weiss, R. F.; Prinn, R. G.

    2012-02-01

    The first atmospheric observations and trends are presented for the high molecular weight perfluorocarbons (PFCs): decafluorobutane (C4F10), dodecafluoropentane (C5F12), tetradecafluorohexane (C6F14), hexadecafluoroheptane (C7F16) and octadecafluorooctane (C8F18). Their atmospheric histories are based on measurements of 38 Northern Hemisphere and 46 Southern Hemisphere archived air samples collected between 1973 to 2011 using the Advanced Global Atmospheric Gases Experiment (AGAGE) "Medusa" preconcentration gas chromatography-mass spectrometry systems. A new calibration scale was prepared for each PFC, with estimated accuracies of 6.8% for C4F10, 7.8% for C5F12, 4.0% for C6F14, 6.6% for C7F16 and 7.9% for C8F18. Based on our observations the 2011 globally averaged dry air mole fractions of these heavy PFCs are: 0.18 parts-per-trillion (ppt, i.e., parts per 1012) for C4F10, 0.12 ppt for C5F12, 0.28 ppt for C6F14, 0.12 ppt for C7F16 and 0.09 ppt for C8F18. These atmospheric mole fractions combine to contribute to a global average radiative forcing of 0.35 mW m-2, which is 3.6% of the total PFC radiative forcing. The globally averaged mean atmospheric growth rates of these PFCs during 1973-2011 are 4.58 parts per quadrillion (ppq, i.e., parts per 1015) per year (yr) for C4F10, 3.29 ppq yr-1 for C5F12, 7.50 ppq yr-1 for C6F14, 3.19 ppq yr-1 for C7F16 and 2.51 ppq yr-1 for C8F18. The growth rates of the heavy perfluorocarbons were largest in the early 1990s for C4F10 and C5F12 and in the mid-to-late 1990s for C6F14, C7F16 and C8F18. The more recent slow down in the growth rates of the high molecular weight PFCs suggests that emissions are declining as compared to the 1980s and 1990s. Nevertheless continued monitoring of these potent, extremely long-lived greenhouse gases is necessary to verify that global PFC emissions continue to decline.

  5. Atmospheric histories and growth trends of C4F10, C5F12, C6F14, C7F16 and C8F18

    NASA Astrophysics Data System (ADS)

    Ivy, D. J.; Arnold, T.; Harth, C. M.; Steele, L. P.; Mühle, J.; Rigby, M.; Salameh, P. K.; Leist, M.; Krummel, P. B.; Fraser, P. J.; Weiss, R. F.; Prinn, R. G.

    2012-05-01

    Atmospheric observations and trends are presented for the high molecular weight perfluorocarbons (PFCs): decafluorobutane (C4F10), dodecafluoropentane (C5F12), tetradecafluorohexane (C6F14), hexadecafluoroheptane (C7F16) and octadecafluorooctane (C8F18). Their atmospheric histories are based on measurements of 36 Northern Hemisphere and 46 Southern Hemisphere archived air samples collected between 1973 to 2011 using the Advanced Global Atmospheric Gases Experiment (AGAGE) "Medusa" preconcentration gas chromatography-mass spectrometry systems. A new calibration scale was prepared for each PFC, with estimated accuracies of 6.8% for C4F10, 7.8% for C5F12, 4.0% for C6F14, 6.6% for C7F16 and 7.9% for C8F18. Based on our observations the 2011 globally averaged dry air mole fractions of these heavy PFCs are: 0.17 parts-per-trillion (ppt, i.e., parts per 1012) for C4F10, 0.12 ppt for C5F12, 0.27 ppt for C6F14, 0.12 ppt for C7F16 and 0.09 ppt for C8F18. These atmospheric mole fractions combine to contribute to a global average radiative forcing of 0.35 mW m-2, which is 6% of the total anthropogenic PFC radiative forcing (Montzka and Reimann, 2011; Oram et al., 2012). The growth rates of the heavy perfluorocarbons were largest in the late 1990s peaking at 6.2 parts per quadrillion (ppq, i.e., parts per 1015) per year (yr) for C4F10, at 5.0 ppq yr-1 for C5F12 and 16.6 ppq yr-1 for C6F14 and in the early 1990s for C7F16 at 4.7 ppq yr-1 and in the mid 1990s for C8F18 at 4.8 ppq yr-1. The 2011 globally averaged mean atmospheric growth rates of these PFCs are subsequently lower at 2.2 ppq yr-1 for C4F10, 1.4 ppq yr-1 for C5F12, 5.0 ppq yr-1 for C6F14, 3.4 ppq yr-1 for C7F16 and 0.9 ppq yr-1 for C8F18. The more recent slowdown in the growth rates suggests that emissions are declining as compared to the 1980s and 1990s.

  6. High-pressure synthesis and characterization of the first cerium fluoride borate CeB{sub 2}O{sub 4}F

    SciTech Connect

    Hinteregger, Ernst; Wurst, Klaus; Tribus, Martina; Huppertz, Hubert

    2013-08-15

    CeB{sub 2}O{sub 4}F is the first cerium fluoride borate, which is exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO{sub 3}]{sup 3−} groups. This new cerium fluoride borate was synthesized under high-pressure/high-temperature conditions of 0.9 GPa and 1450 °C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pbca (No. 61) with eight formula units and the lattice parameters a=821.63(5), b=1257.50(9), c=726.71(6) pm, V=750.84(9) Å{sup 3}, R{sub 1}=0.0698, and wR{sub 2}=0.0682 (all data). The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO{sub 3}]{sup 3−} groups. Furthermore, IR spectroscopy, Electron Micro Probe Analysis and temperature-dependent X-ray powder diffraction measurements were performed. - Graphical abstract: A new rare-earth fluoride borate CeB{sub 2}O{sub 4}F could be synthesized under high-pressure/high-temperature conditions of 0.9 °GPa and 1450 °Cin a Walker-type multianvil apparatus. The crystal structure represents a new structure type in the class of rare-earth fluoride borates. The structure exhibits a 9+1 coordinated cerium ion, one three-fold coordinated fluoride ion and a one-dimensional chain of [BO{sub 3}]{sup 3−} groups. A closer view on the ac-plane shows an interesting wave-like modulation of the borate chains. Highlights: • CeB{sub 2}O{sub 4}F is the first fluoride borate exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO{sub 3}]{sup 3−} groups. • CeB{sub 2}O{sub 4}F is the first cerium fluoride borate. • High-pressure conditions were necessary to synthesize CeB{sub 2}O{sub 4}F.

  7. Electronic state of ruthenium deposited onto oxide supports: An XPS study taking into account the final state effects

    NASA Astrophysics Data System (ADS)

    Larichev, Yurii V.; Moroz, Boris L.; Bukhtiyarov, Valerii I.

    2011-12-01

    The electronic state of ruthenium in the supported Ru/EOx (EOx = MgO, Al2O3 or SiO2) catalysts prepared by with the use of Ru(OH)Cl3 or Ru(acac)3 (acac = acetylacetonate) and reduced with H2 at 723 K is characterized by X-ray photoelectron spectroscopy (XPS) in the Ru 3d, Cl 2p and O 1s regions. The influence of the final state effects (the differential charging and variation of the relaxation energy) on the binding energy (BE) of Ru 3d5/2 core level measured for supported Ru nanoparticles is estimated by comparison of the Fermi levels and the modified Auger parameters determined for the Ru/EOx samples with the corresponding characteristics of the bulk Ru metal. It is found that the negative shift of the Ru 3d5/2 peak which is observed in the spectrum of ruthenium deposited onto MgO (BE = 279.5-279.7 eV) with respect to that of Ru black (BE = 280.2 eV) or ruthenium supported on γ-Al2O3 and SiO2 (BE = 280.4 eV) is caused not by the transfer of electron density from basic sites of MgO, as considered earlier, but by the differential charging of the supported Ru particles compared with the support surface. Correction for the differential charging value reveals that the initial state energies of ruthenium in the Ru/EOx systems are almost identical (BE = 280.5 ± 0.1 eV) irrespectively of acid-base properties of the support, the mean size of supported Ru crystallites (within the range of 2-10 nm) and the surface Cl content. The results obtained suggest that the difference in ammonia synthesis activity between the Ru catalysts supported on MgO and on the acidic supports is accounted for by not different electronic state of ruthenium on the surface of these oxides but by some other reasons.

  8. XPS investigation of ion beam induced conversion of GaAs(0 0 1) surface into GaN overlayer

    NASA Astrophysics Data System (ADS)

    Kumar, Praveen; Kumar, Mahesh; Govind; Mehta, B. R.; Shivaprasad, S. M.

    2009-10-01

    For the advance of GaN based optoelectronic devices, one of the major barriers has been the high defect density in GaN thin films, due to lattice parameter and thermal expansion incompatibility with conventional substrates. Of late, efforts are focused in fine tuning epitaxial growth and in search for a low temperature method of forming low defect GaN with zincblende structure, by a method compatible to the molecular beam epitaxy process. In principle, to grow zincblende GaN the substrate should have four-fold symmetry and thus zincblende GaN has been prepared on several substrates including Si, 3C-SiC, GaP, MgO, and on GaAs(0 0 1). The iso-structure and a common shared element make the epitaxial growth of GaN on GaAs(0 0 1) feasible and useful. In this study ion-induced conversion of GaAs(0 0 1) surface into GaN at room temperature is optimized. At the outset a Ga-rich surface is formed by Ar + ion bombardment. Nitrogen ion bombardment of the Ga-rich GaAs surface is performed by using 2-4 keV energy and fluence ranging from 3 × 10 13 ions/cm 2 to 1 × 10 18 ions/cm 2. Formation of surface GaN is manifested as chemical shift. In situ core level and true secondary electron emission spectra by X-ray photoelectron spectroscopy are monitored to observe the chemical and electronic property changes. Using XPS line shape analysis by deconvolution into chemical state, we report that 3 keV N 2+ ions and 7.2 × 10 17 ions/cm 2 are the optimal energy and fluence, respectively, for the nitridation of GaAs(0 0 1) surface at room temperature. The measurement of electron emission of the interface shows the dependence of work function to the chemical composition of the interface. Depth profile study by using Ar + ion sputtering, shows that a stoichiometric GaN of 1 nm thickness forms on the surface. This, room temperature and molecular beam epitaxy compatible, method of forming GaN temperature can serve as an excellent template for growing low defect GaN epitaxial overlayers.

  9. XRD and XPS analysis of the degradation of the polymer electrolyte in H 2-O 2 fuel cell

    NASA Astrophysics Data System (ADS)

    Huang, Chengde; Seng Tan, Kim; Lin, Jianyi; Lee Tan, Kuang

    2003-03-01

    Nafion ® is frequently used as electrolyte membrane in polymer electrolyte fuel cells (PEFC). In this Letter the degradation of the Nafion ® polymer electrolyte was investigated using X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD showed that the electrode potential and low gas humidification temperature could decrease the crystallinity of Nafion ®. XPS analysis indicated that the Nafion ® was decomposed in the hydrogen potential region of the fuel cell, through the interaction of the hydrophobic (CF 2) n groups of the membrane with H or/and C atoms.

  10. Insights into stability, electronic properties, defect properties and Li ions migration of Na, Mg and Al-doped LiVPO4F for cathode materials of lithium ion batteries: A first-principles investigation

    NASA Astrophysics Data System (ADS)

    Lv, Xiaojun; Xu, Zhenming; Li, Jie; Chen, Jiangan; Liu, Qingsheng

    2016-07-01

    The effects of Na, Mg and Al doping on the structure, electronic property, defect property and Li ions migration of LiVPO4F were investigated by the first-principles method. Calculations show that the processes of forming Li0.875Na0.125VPO4F, α- and β-LiMg0.375V0.75PO4F, α- and β-LiAl0.125V0.875PO4F are all feasible. Na, Mg and Al doping significantly improve the electrical conductivity of LiVPO4F and simultaneously maintain their structural stability attributing to the reduction of band gaps through variations of V-3d spin up orbitals. Li vacancy defects of LiVPO4F are not ignorable, and vacancy defects with a lower activation energy for Li atom are far more likely to occur than Frenkel defects for Li and vacancy defects for other atoms. For pristine LiVPO4F, path D along [0.012 0 . 17 ̅ 0.572] direction is found to have the lowest activation energy of 0.418 eV, suggesting that anisotropic nature of Li ion conduction and LiVPO4F is a one-dimensional (1D)-ion conductor. The corresponding diffusion coefficient was estimated to be 2.82×10-9 cm2/s, which is in good agreement with those experimental values.

  11. Investigation of autoionization spectra of Sm atoms using an isolated-core excitation method

    NASA Astrophysics Data System (ADS)

    Qin, Wen-Jie; Dai, Chang-Jian; Xiao, Ying; Zhao, Hong-Ying

    2009-05-01

    Using the isolated-core-excitation scheme and three-step laser resonance ionization spectroscopy approach, this paper, for the first time, has systematically investigated the autoionization spectra of atomic Sm, belonging to the 4f66pnl and 4f55d6snl (l = 0,2) configurations. In the experiment, the first two tunable dye lasers are employed to excite the Sm atom from its initial state to the different 4f66snl bound Rydberg states, then the third dye laser is scanned to drive the atom to the doubly-excited autoionizing states. With the above excitation scheme, the measured transition profiles of the autoionizing states are nearly symmetric, from which the level energies and widths can be easily obtained.

  12. Evidence that the transport-related proteins BAT and 4F2hc are not specific for amino acids: induction of Na+-dependent uridine and pyruvate transport activity by recombinant BAT and 4F2hc expressed in Xenopus oocytes.

    PubMed

    Yao, S Y; Muzyka, W R; Cass, C E; Cheeseman, C I; Young, J D

    1998-01-01

    Members of the BAT and 4F2hc gene family have one or, in the case of BAT, up to four transmembane domains and induce amino acid transport systems b(o,+) (BAT) and y+L (4F2hc) when expressed in Xenopus oocytes. System b(o,+) is a Na+-independent process with a broad tolerance for cationic and zwitterionic amino acids, whereas y+L exhibits Na+-independent transport of cationic amino acids (e.g., lysine) and Na+-dependent transport of zwitterionic amino acids (e.g., leucine). Mutations in the human BAT gene are associated with type I cystinuria, a genetic disease affecting the ability of intestinal and renal brush border membranes to transport cationic amino acids and cystine. An unresolved question is whether BAT and 4F2hc themselves have catalytic (i.e., transporting) activity or whether they operate as activators of other, as yet unidentified, transporter proteins. In this report, we have investigated the transport of representatives of four different classes of organic substrates in Xenopus oocytes following injection with rat BAT or 4F2hc RNA transcripts: leucine (a control amino acid substrate), uridine (a nucleoside), pyruvate (a monocarboxylate), and choline (an amine). Both recombinant proteins induced small, statistically significant Na+-dependent fluxes of uridine and pyruvate but had no effect on choline uptake. In contrast, control oocytes injected with transcripts for conventional nucleoside and cationic amino acid transporters (rat CNT1 and murine CAT1, respectively) showed no induction of transport of either leucine or pyruvate (CNT1) or uridine or pyruvate (CAT1). These findings support the idea that BAT and 4F2hc are transport activators and minimize the possibility that they have intrinsic transport capability. The transport-regulating functions of these proteins may extend to permeants other than amino acids. PMID:10353721

  13. Elastic modulus, oxidation depth and adhesion force of surface modified polystyrene studied by AFM and XPS

    NASA Astrophysics Data System (ADS)

    Lubarsky, G. V.; Davidson, M. R.; Bradley, R. H.

    2004-06-01

    AFM and XPS have been used to investigate the surface and near-surface properties of polystyrene (PS) substrates which have been subjected to one of three controlled surface modification processes performed in situ in a specially constructed cell. The cell was fitted to a Digital Instruments Nanoscope III AFM measuring head and allowed close control of the gaseous environment and made it possible to UV irradiate the sample during AFM measurements. Treatments were carried out using UV at 184.9 and 253.7 nm wavelengths, in oxygen (UV-ozone), and in nitrogen (UV-only). Polystyrene surfaces were also modified by an exposure to an atmosphere of ozone in the absence of UV (ozone-only). Data show that adhesion force is highest between tip and sample for the UV-ozone exposed surfaces and that the adhesion force increases with sample exposure time. Exposure to UV-only or ozone alone results in lower ultimate adhesion levels with a slower rate of increase with exposure time. Evaluation of Young's modulus for unmodified PS gave a value of 3.37 (±0.52) GPa which agrees well with the textbook value which ranges from 2 to 4 GPa depending on the measurement technique. A 60 s exposure to combined UV-ozone resulted in the formation of a surface layer with a modulus at the surface of 1.25 (±0.19) GPa which increased to 2.5 (±0.37) GPa at a depth of 3.5 nm. The sample exposed for 60 s to UV-only had a Young's modulus of 2.6 (±0.39) GPa but showed no reduced modulus layer at the surface. The modulus of the ozone-only treated material was the least affected with a decrease of around 0.75 GPa with some evidence for a surface layer with a modulus ranging from 2.6 (±0.39) GPa at the surface to 3.2 (±0.48) GPa at a depth of 2 nm. XPS analyses reveal that the oxygen content of the modified surfaces decreased in the order of UV-ozone > UV > ozone with approximate concentrations for a 60 s exposure of 5, 0.7 and 0.05 at.%, respectively. Friction force imaging of patterned surfaces

  14. Global emission estimates and radiative impact of C4F10, C5F12, C6F14, C7F16 and C8F18

    NASA Astrophysics Data System (ADS)

    Ivy, D. J.; Rigby, M.; Baasandorj, M.; Burkholder, J. B.; Prinn, R. G.

    2012-05-01

    Global emission estimates based on new atmospheric observations are presented for the acylic high molecular weight perfluorocarbons (PFCs): decafluorobutane (C4F10), dodecafluoropentane (C5F12), tetradecafluorohexane (C6F14), hexadecafluoroheptane (C7F16) and octadecafluorooctane (C8F18). Emissions are estimated using a 3-dimensional chemical transport model and an inverse method that includes a growth constraint on emissions. The observations used in the inversion are based on newly measured archived air samples that cover a 39-yr period, from 1973 to 2011, and include 36 Northern Hemispheric and 46 Southern Hemispheric samples (Ivy et al., 2012). The derived emission estimates show that global emission rates were largest in the 1980s and 1990s for C4F10 and C5F12, and in the 1990s for C6F14,C7F16 and C8F18. After a subsequent decline, emissions have remained relatively stable, within 20%, for the last 5 yr. Bottom-up emission estimates are available from the Emission Database for Global Atmospheric Research version 4.2 (EDGARv4.2) for C4F10, C5F12, C6F14 and C7F16, and inventories of C4F10, C5F12 andC6F14 are reported to the United Nations' Framework Convention on Climate Change (UNFCCC) by Annex 1 countries that have ratified the Kyoto Protocol. The atmospheric measurement based emission estimates are 20 times larger than EDGARv4.2 for C4F10 and over three orders of magnitude for C5F12. The derived emission estimates for C6F14 largely agree with the bottom-up estimates from EDGARv4.2. Moreover, the C7F16 emission estimates are comparable to those of EDGARv4.2 at their peak in the 1990s, albeit significant underestimation for the other time periods. There are no bottom-up emission estimates for C8F18, thus the emission rates reported here are the first for C8F18. The reported inventories for C4F10, C5F12 and C6F14 to UNFCCC are five to ten times lower than those estimated in this study. In addition, we present measured infrared absorption spectra for C7F16 and C8

  15. Global emission estimates and radiative impact of C4F10, C5F12, C6F14, C7F16 and C8F18

    NASA Astrophysics Data System (ADS)

    Ivy, D. J.; Rigby, M.; Baasandorj, M.; Burkholder, J. B.; Prinn, R. G.

    2012-08-01

    Global emission estimates based on new atmospheric observations are presented for the acylic high molecular weight perfluorocarbons (PFCs): decafluorobutane (C4F10), dodecafluoropentane (C5F12), tetradecafluorohexane (C6F14), hexadecafluoroheptane (C7F16) and octadecafluorooctane (C8F18). Emissions are estimated using a 3-dimensional chemical transport model and an inverse method that includes a growth constraint on emissions. The observations used in the inversion are based on newly measured archived air samples that cover a 39-yr period, from 1973 to 2011, and include 36 Northern Hemispheric and 46 Southern Hemispheric samples. The derived emission estimates show that global emission rates were largest in the 1980s and 1990s for C4F10 and C5F12, and in the 1990s for C6F14, C7F16 and C8F18. After a subsequent decline, emissions have remained relatively stable, within 20%, for the last 5 yr. Bottom-up emission estimates are available from the Emission Database for Global Atmospheric Research version 4.2 (EDGARv4.2) for C4F10, C5F12, C6F14 and C7F16, and inventories of C4F10, C5F12 and C6F14 are reported to the United Nations' Framework Convention on Climate Change (UNFCCC) by Annex 1 countries that have ratified the Kyoto Protocol. The atmospheric measurement-based emission estimates are 20 times larger than EDGARv4.2 for C4F10 and over three orders of magnitude larger for C5F12 (with 2008 EDGARv4.2 estimates for C5F12 at 9.6 kg yr-1, as compared to 67±53 t yr-1 as derived in this study). The derived emission estimates for C6F14 largely agree with the bottom-up estimates from EDGARv4.2. Moreover, the C7F16 emission estimates are comparable to those of EDGARv4.2 at their peak in the 1990s, albeit significant underestimation for the other time periods. There are no bottom-up emission estimates for C8F18, thus the emission rates reported here are the first for C8F18. The reported inventories for C4F10, C5F12 and C6F14 to UNFCCC are five to ten times lower than those

  16. Incorporation of amino acids within the surface reactive layers of bioactive glass in vitro: an XPS study.

    PubMed

    Mahmood, T A; Davies, J E

    2000-01-01

    Surface reaction layers grown on bioactive glass (Bioglass), by immersion in either simulated body fluid (SBF) or minimal essential medium (alpha-MEM) for 2, 5, 32 and 72 h, were analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Layers grown in alpha-MEM exhibited delamination when observed in SEM. Low resolution XPS analysis detected nitrogen at the surface of the Bioglass exposed to alpha-MEM for 72 h (8 relative at%), whereas insignificant nitrogen was found at the surface of any sample immersed in SBF. XPS depth profiling (argon) showed the presence of nitrogen throughout the depth of the surface layer of the sample incubated in alpha-MEM for 72 h. Deconvolution of the nitrogen envelope in a high resolution XPS spectrum demonstrated nitrogen characteristic of the amine bonds present in amino acids. Carbon concentration also considerably increased over time with exposure to alpha-MEM (24-55%), whereas it remained in the 20-25% range in SBF. These results demonstrate that the amino acids contained in the culture medium were incorporated within the growing calcium phosphate rich surface reaction layer of Bioglass. PMID:15348094

  17. Structural and XPS studies of PSi/TiO2 nanocomposites prepared by ALD and Ag-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Iatsunskyi, Igor; Kempiński, Mateusz; Nowaczyk, Grzegorz; Jancelewicz, Mariusz; Pavlenko, Mykola; Załęski, Karol; Jurga, Stefan

    2015-08-01

    PSi/TiO2 nanocomposites fabricated by atomic layer deposition (ALD) and metal-assisted chemical etching (MACE) were investigated. The morphology and phase structure of PSi/TiO2 nanocomposites were studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) with an energy dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. The mean size of TiO2 nanocrystals was determined by TEM and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical elemental composition by observing the behavior of the Ti 2p, O 1s and Si 2p lines. TEM, Raman spectroscopy and XPS binding energy analysis confirmed the formation of TiO2 anatase phase inside the PSi matrix. The XPS valence band analysis was performed in order to investigate the modification of PSi/TiO2 nanocomposites electronic structure. Surface defects states of Ti3+ at PSi/TiO2 nanocomposites were identified by analyzing of XPS valence band spectra.

  18. Impact of genetic factors (VKORC1, CYP2C9, CYP4F2 and EPHX1) on the anticoagulation response to fluindione

    PubMed Central

    Lacut, Karine; Ayme-Dietrich, Estelle; Gourhant, Lenaick; Poulhazan, Elise; Andro, Marion; Becquemont, Laurent; Mottier, Dominique; Le Gal, Gregoire; Verstuyft, Celine

    2012-01-01

    AIM Genetic variants of the enzyme that metabolizes warfarin, cytochrome P-450 2C9 (CYP2C9) and of a key pharmacologic target of vitamin K antagonists, vitamin K epoxide reductase (VKORC1), contribute to differences in patients' responses to coumarin derivatives. The role of these variants in fluindione response is unknown. Our aim was to assess whether genetic factors contribute to the variability in the response to fluindione. METHODS Four hundred sixty-five patients with a venous thromboembolic event treated by fluindione for at least 3 months with a target international normalized ratio (INR) of 2.0 to 3.0 were studied. VKORC1, CYP2C9, CYP4F2 and EPHX1 genotypes were assessed. INR checks, fluindione doses and bleeding events were collected. RESULTS VKORC1 genotype had a significant impact on early anticoagulation (INR value ≥2 after the first two intakes) (P < 0.0001), on the time required to reach a first INR within the therapeutic range (P < 0.0001) and on the time to obtain a first INR value > 4 (P = 0.0002). The average daily dose of fluindione during the first period of stability was significantly associated with the VKORC1 genotype: 19.8 mg (±5.5) for VKORC1 CC, 14.7 mg (±6.2) for VKORC1 CT and 8.2 mg (±2.5) for VKORC1 TT (P < 0.0001). CYP2C9, CYP4F2 and EPHX1 genotypes did not significantly influence the response to fluindione. CONCLUSIONS VKORC1 genotype strongly affected anticoagulation induced by fluindione whereas CYP2C9, CYP4F2 and EPHX1 genotypes seemed less determining. PMID:21883387

  19. Fe{sub 2}(AsO{sub 4})F: A new three-dimensional condensed fluoro-arsenate iron(II) compound with antiferromagnetic interactions

    SciTech Connect

    Berrocal, Teresa; Mesa, Jose L. . E-mail: qipmeruj@lg.ehu.es; Pizarro, Jose L.; Urtiaga, Miren K.; Arriortua, Maria I.; Rojo, Teofilo . E-mail: qiproapt@lg.ehu.es

    2006-06-15

    Fe{sub 2}(AsO{sub 4})F has been synthesized under mild hydrothermal conditions in the form of single crystals. The compound crystallizes in C2/c monoclinic space group with the unit cell parameters a=13.214(1), b=6.623(1), c=10.045(1)A and {beta}=116.90(2) deg. with Z=8. The crystal structure consists of a three-dimensional framework constructed by two kinds of chains, A and B, with 50% of population. In the chains, the environments for the iron(II) cations show penta- and hexa-coordination. The chains establish an angle of approximately 120 deg. between them. The disordered fluoride anions in these chains given rise to [Fe(1)O{sub 4}F(1){sub 0.5}(F(2){sub 0.5}){sub 2}] and [Fe(2)O{sub 4}(F(1){sub 0.5}){sub 2}F(2){sub 0.5}] edge-shared polyhedra in which the fluoride anions have occupancy factors of 50% over two distinct crystallographic sites. The IR spectrum shows the characteristic bands of the (AsO{sub 4}){sup 3-} groups. From the diffuse reflectance spectrum a D{sub q} parameter of 650cm{sup -1} has been calculated for the Fe(II) d{sup 6} high spin cation. The Mossbauer spectrum in the paramagnetic state shows a doublet that has been fitted, according to the existence of two crystallographically independent iron environments, with two Lorentzian doublets. Magnetic measurements performed between room temperature and 5K exhibit a maximum at 22.6K, characteristic of antiferromagnetic interactions with a estimated 'J'-exchange parameter of -1.2K.

  20. Diode-pumped Nd:YVO4 laser emitting at 1074 nm based on the 4 F 3/2-4 I 11/2 transition

    NASA Astrophysics Data System (ADS)

    Ma, Z. Y.; Li, C. L.; Liang, W.; Wang, J. G.

    2011-09-01

    We report a diode-pumped Nd:YVO4 laser emitting at 1074 nm, based on the 4 F 3/2-4 I 11/2 transition, generally used for a 1064 nm emission. A power of 323 mW at 1074 nm has been achieved in continuouswave (CW) operation with a fiber-coupled laser diode emitting 18.2 W at 808 nm. Intracavity second-harmonic generation in CW mode has also been demonstrated with a power of 18 mW at 537 nm by using a LiB3O5 (LBO) nonlinear crystal.

  1. Electronic structure and 3d-4f exchange interactions in zircon-type RCrO{sub 4} oxides (R=Dy, Ho and Gd)

    SciTech Connect

    Ray, Avijeet Maitra, Tulika

    2015-06-24

    Using first principles density functional theory (DFT) calculations within GGA and GGA+U approximations we studied both ferromagnetic (FM) and antiferromagnetic (AFM) phases of zircon type RCrO{sub 4} (R= Dy, Ho, Gd) oxides. We estimated and compared the 3d-4f exchange interaction strengths J between the nearest neighbor R{sup 3+} and Cr{sup 5+} ions for R=Dy, Gd. Our results predict that DyCrO{sub 4}, GdCrO{sub 4} and HoCrO{sub 4} have ferromagnetic ground state which is consistent with experimental observations.

  2. Energy transfer and non-linear optical properties at near ultraviolet wavelengths: Rare earth 4f yields 5d transitions in crystals and glasses

    NASA Astrophysics Data System (ADS)

    Hamilton, D. S.

    1992-08-01

    The following topics were studied: two-photon transitions from 4f ground state to 5d excited states in Ce(3+):CaF2; optical absorption and photoionization measurements from excited state of Ce(3+):Y3Al5O12; excited state photoionization of Ce(3+) ions in Ce(3+):CaF2; optical gain and loss studies in Ce(3+):LiYF4; Gd yields Cr energy transfer in Cr(3+):GSGG, Cr(3+):GSAG, and Cr(3+):GGG crystals; nonradiative relaxation in Ce(3+) doped crystals and glasses; and grating formation in impurity doped crystals.

  3. Volumetric Properties of the Mixture 1,4-Difluorobenzene C6H4F2 + C16H34 Hexadecane (VMSD1111, LB5103_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 1,4-Difluorobenzene C6H4F2 + C16H34 Hexadecane (VMSD1111, LB5103_V)' providing data from direct low-pressure measurement of mass density at variable mole fraction and constant temperature, in the single-phase region(s).

  4. Volumetric Properties of the Mixture 1,4-Difluorobenzene C6H4F2 + C16H34 Hexadecane (VMSD1212, LB5098_V)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Volumetric Properties of the Mixture 1,4-Difluorobenzene C6H4F2 + C16H34 Hexadecane (VMSD1212, LB5098_V)' providing data by calculation of molar excess volume from low-pressure density measurements at variable mole fraction and constant temperature.

  5. Heat of Mixing and Solution of 1,4-Difluorobenzene C6H4F2 + C16H34 Hexadecane (HMSD1111, LB4307_H)

    NASA Astrophysics Data System (ADS)

    Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

    This document is part of Subvolume B 'Binary Liquid Systems of Nonelectrolytes II' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Heat of Mixing and Solution of 1,4-Difluorobenzene C6H4F2 + C16H34 Hexadecane (HMSD1111, LB4307_H)' providing data from direct low-pressure calorimetric measurement of molar excess enthalpy at variable mole fraction and constant temperature.

  6. A vibrational spectroscopic study of a hydrated hydroxy-phosphate mineral fluellite, Al2(PO4)F2(OH)·7H2O.

    PubMed

    Cejka, Jiří; Sejkora, Jiří; Macek, Ivo; Frost, Ray L; López, Andrés; Scholz, Ricardo; Xi, Yunfei

    2014-05-21

    Raman and infrared spectra of two well-defined fluellite samples, Al2(PO4)F2(OH)·7H2O, from the Krásno near Horní Slavkov (Czech Republic) and Kapunda, South Australia (Australia) were studied and tentatively interpreted. Observed bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, aluminum oxide/hydroxide/fluoride octahedra, water molecules and hydroxyl ions. Approximate O-H⋅⋅⋅O hydrogen bond lengths were inferred from the Raman and infrared spectra. PMID:24594888

  7. XPS analysis of 440C steel surfaces lubricated with perfluoropolyethers under sliding conditions in high vacuum

    SciTech Connect

    Herrera-Fierro, P.; Masuko, M.; Jones, W.R. Jr.; Pepper, S.V.

    1994-04-01

    This work presents the results of the X-Ray Photoelectron Spectroscopy (XPS) analysis of AISI 440C ball surfaces lubricated with perfluoropolyether (PFPE) oils after friction experiments under sliding conditions at high load in air and vacuum environments. The PFPE lubricants tested were Demnum S100, Fomblin Z-25, and Krytox 143AB. It was found that all the PFPE lubricants were degraded by sliding contact causing the formation of inorganic fluorides on the metallic surfaces and a layer of organic decomposition products. KRYTOX 143AB was the least reactive of the three lubricants tested. It was also found that metal fluoride formed at off-scar areas. This suggests the formation of reactive species, such as COF2 or R[sub f]COF, during sliding experiments, which can diffuse through the lubricant film and react with the metallic surfaces away from the contact region. Comparison of reference specimens before sliding with those that had undergone the sliding tests showed that the amount of non-degraded PFPE remaining on the surface of the balls after the sliding experiments was greater than that of the balls without sliding.

  8. RBS and XPS analyses of the composite calcium phosphate coatings for biomedical applications

    NASA Astrophysics Data System (ADS)

    Ide-Ektessabi, Ari; Yamaguchi, Tetsuro; Tanaka, Yoshikazu

    2005-12-01

    The calcium phosphate coatings on metallic implants are widely used for biomedical applications. The calcium phosphate coatings require mechanical strength, strong adhesion to the metallic implants, chemical stability and low dissolution into the human body fluid for stable functioning in the corrosive environment of the human body. In this study, a novel approach for improving the calcium phosphate coatings is utilized by adding trace metallic element into the coatings. We focused on teeth enamel, which is the hardest calcium phosphate tissue in the human body. Zn concentration increases exponentially from the interior to the surface of the enamel. As the Zn concentration increases, so the local hardness increases. Our previous studies suggest that Zn has influence on the hardness and other properties of enamel, calcium phosphate tissue. Calcium phosphate coatings doped with Zn was fabricated and characterized. The atomic composition and chemical state were investigated by using Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectrometer (XPS), respectively. Scratch test was also carried out for measuring the adhesion of the coatings.

  9. Soft X-ray-induced decomposition of amino acids: An XPS, massspectrometry, and NEXAFS study

    SciTech Connect

    Zubavichus, Y.; Fuchs, O.; Weinhardt, L.; Heske, C.; Umbach, E.; Denlinger, J.D.; Grunze, M.

    2003-02-26

    Decomposition of five amino acids, viz. alanine, serine,cysteine, aspartic acid, and asparagine under soft X-ray irradiation (MgKα X-ray source) in ultra-high vacuum has been studied by meansof XPS and mass-spectrometry. A comparative analysis of changes in XPSline shapes, stoichiometry, and residual gas composition indicates thatthe molecules decompose via severalpathways. Dehydration,decarboxylation, decarbonylation, deamination, and desulfurization ofpristine molecules accompanied by desorption of H2, H2O, CO2, CO, NH3,H2S are observed with rates depending on the specific amino acid. NEXAFSspectra of cysteine at the C, O, N K- and S L2,3-edges complement the XPSand mass-spectrometry data and show that exposure of the sample to anintense soft X-ray synchrotron beam results in a formation of C-C and C-Ndouble and triple bonds. Qualitatively, the studied amino acids can bearranged in the following ascending order for radiation stability: serine

  10. XPS analysis of 440C steel surfaces lubricated with perfluoropolyethers under sliding conditions in high vacuum

    NASA Technical Reports Server (NTRS)

    Herrera-Fierro, Pilar; Masuko, Masabumi; Jones, William R., Jr.; Pepper, Stephen V.

    1994-01-01

    This work presents the results of the X-Ray Photoelectron Spectroscopy (XPS) analysis of AISI 440C ball surfaces lubricated with perfluoropolyether (PFPE) oils after friction experiments under sliding conditions at high load in air and vacuum environments. The PFPE lubricants tested were Demnum S100, Fomblin Z-25, and Krytox 143AB. It was found that all the PFPE lubricants were degraded by sliding contact causing the formation of inorganic fluorides on the metallic surfaces and a layer of organic decomposition products. KRYTOX 143AB was the least reactive of the three lubricants tested. It was also found that metal fluoride formed at off-scar areas. This suggests the formation of reactive species, such as COF2 or R(sub f)COF, during sliding experiments, which can diffuse through the lubricant film and react with the metallic surfaces away from the contact region. Comparison of reference specimens before sliding with those that had undergone the sliding tests showed that the amount of non-degraded PFPE remaining on the surface of the balls after the sliding experiments was greater than that of the balls without sliding.

  11. XPS analysis of the effect of fillers on PTFE transfer film development in sliding contacts

    NASA Technical Reports Server (NTRS)

    Blanchet, T. A.; Kennedy, F. E.; Jayne, D. T.

    1993-01-01

    The development of transfer films atop steel counterfaces in contact with unfilled and bronze-filled PTFE has been studied using X-ray photoelectron spectroscopy. The sliding apparatus was contained within the vacuum of the analytical system, so the effects of the native oxide, hydrocarbon, and adsorbed gaseous surface layers of the steel upon the PTFE transfer behavior could be studied in situ. For both the filled and the unfilled PTFE, cleaner surfaces promoted greater amounts of transfer. Metal fluorides, which formed at the transfer film/counterface interface, were found solely in cases where the native oxide had been removed to expose the metallic surface prior to sliding. These fluorides also were found at clean metal/PTFE interfaces formed in the absence of frictional contact. A fraction of these fluorides resulted from irradiation damage inherent in XPS analysis. PTFE transfer films were found to build up with repeated sliding passes, by a process in which strands of transfer filled in the remaining counterface area. Under these reported test conditions, the transfer process is not expected to continue atop previously deposited transfer films. The bronze-filled composite generated greater amounts of transfer than the unfilled PTFE. The results are discussed relative to the observed increase in wear resistance imparted to PTFE by a broad range of inorganic fillers.

  12. Local, global and electronic structure of supported gold nanoclusters determined by EXAFS, XRD and XPS methods

    NASA Astrophysics Data System (ADS)

    Aldea, Nicolae; Rednic, Vasile; Pintea, Stelian; Marginean, Petru; Barz, Bogdan; Gluhoi, Andreea; Nieuwenhuys, Bernard E.; Neumann, Manfred; Yaning, Xie; Matei, Florica

    2009-07-01

    We analyze gold nanoclusters as supported catalysts by extended X-ray absorption fine structure, X-ray diffraction and X-ray photoelectron spectroscopy in order to determine their local, global and electronic structure. The present study points out a strong deformation of the local structure of the metal due to its interaction with oxide supports. We determine the particle size distribution and microstrain functions of the Au nanoclusters by X-ray diffraction method. Based on X-ray absorption fine structure spectroscopy analysis we show that the entire local structure of the investigated systems is strongly distorted regarding the average Au-Au coordination number. The distances between atoms are practically the same as standard Au foil. The strong metal-support interaction is confirmed by the change in shape of the electron transition probability densities that appear in the Au L III-edge. From XPS investigations we find electronic states corresponding to gold as well as to the oxide supports.

  13. Compositional aspect of iron Fischer-Tropsch catalyst: An XPS/reaction study

    SciTech Connect

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

    1989-08-01

    The catalytic and compositional behaviors of prereduced and unreduced iron catalysts for Fischer-Tropsch synthesis were investigated. Catalytic behavior was evaluated by measuring rates of hydrocarbon formation 3:1 H{sub 2}:CO mixture at 1 atm and 250C. Iron phases which evolved near the catalyst surfaces were characterized by X-ray photoelectron spectroscopy, and bulk phases present following reaction were determined by Moessbauer spectroscopy. At low conversion levels the prereduced catalyst was gradually converted to iron carbide with no significant oxide phase formed. Synthesis activities increased initially with the formation of active surface carbon, but eventually lost some activity due to graphitic carbon formation. At higher conversions, the prereduced catalyst showed some formation of surface oxide phases and an inhibition of the synthesis rate due to water adsorption. Surface carbon accumulation was also suppressed under these conditions. Unreduced Fe{sub 2}O{sub 3} showed no initial synthesis activity, but underwent a gradual activation to become even more active than the prereduced catalyst. The oxide catalyst was eventually completely reduced to Fe{sub 3}O{sub 4}, and any metallic phase formed was rapidly converted to iron carbide. Compared to reduced materials, the oxide catalyst accumulated considerably less surface carbon and showed no loss of activity for reaction times up to 48 h. XPS analysis suggests that Fe{sub 3}O{sub 4} is active for synthesis.

  14. Corrosion prevention capability of polyaniline (emeraldine base and salt): An XPS study

    SciTech Connect

    Jasty, S.; Epstein, A.J.

    1995-12-01

    There has been a keen interest in the use of polyaniline coatings for the corrosion protection of Fe and its alloys. To date, the primary focus has been on the doped form of the emeraldine oxidation state; also, the polyaniline has been applied, electrochemically or chemically, as an overcoat on the metal. In the present study, the surface sensitive XPS technique has been applied to investigate (1) the effectiveness of the neutral emeraldine base as well as the doped emeraldine hydrochloride forms of polyaniline in corrosion inhibition and (2) the ability of a polyaniline undercoat in providing corrosion protection by passivating the exposed metal surface. Here 350{Angstrom} and 70{Angstrom} thick Fe was sputter deposited onto the polyaniline and control polymer (non-electroactive) substrates and exposed to different environments. We conclude that an undercoat of the neutral emeraldine base form of polyaniline passivates the outer metal (Fe) surface with a thin ({approximately} 30-50{Angstrom}) oxide layer of mainly hematite (Fe{sub 2}O{sub 3}) and that the passivation mechanism has an electronic origin. In contrast, Fe sputtered onto doped emeraldine hydrochloride forms a thicker oxide layer with a distribution of oxidation states, effectively providing much less corrosion protection.

  15. The nature of nitrate at the ice surface studied by XPS and NEXAFS.

    PubMed

    Krepelová, Adéla; Newberg, John; Huthwelker, Thomas; Bluhm, Hendrik; Ammann, Markus

    2010-08-21

    Trace contaminants such as strong acids have been suggested to affect the thickness of the quasi-liquid layer at the ice/air interface, which is at the heart of heterogeneous chemical reactions between snowpacks or cirrus clouds and the surrounding air. We used X-ray photoelectron spectroscopy (XPS) and electron yield near edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Advanced Light Source (ALS) to probe the ice surface in the presence of HNO(3) formed from the heterogeneous hydrolysis of NO(2) at 230 K. We studied the nature of the adsorbed species at the ice/vapor interfaces as well as the effect of HNO(3) on the hydrogen bonding environment at the ice surface. The NEXAFS spectrum of ice with adsorbed HNO(3) can be represented as linear combination of the clean ice and nitrate solution spectrum, thus indicating that in the presence of HNO(3) the ice surface consists of a mixture of clean ice and nitrate ions that are coordinated as in a concentrated solution at the same temperature but higher HNO(3) pressures. PMID:20532376

  16. XPS and STM studies of the oxidation of hydrogen chloride at Cu(100) surfaces

    NASA Astrophysics Data System (ADS)

    Altass, Hatem; Carley, Albert F.; Davies, Philip R.; Davies, Robert J.

    2016-08-01

    The dissociative chemisorption of HCl on clean and oxidized Cu(100) surfaces has been investigated using x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Whereas the dissociation of HCl at the clean surface is limited to the formation of a (√ 2 × √ 2)-R45° Cl(a) monolayer, the presence of surface oxygen removes this barrier, leading to chlorine coverages up to twice that obtained at the clean surface. Additional features in the STM images that appear at these coverages are tentatively assigned to the nucleation of CuCl islands. The rate of reaction of the HCl was slightly higher on the oxidized surface but unaffected by the initial oxygen concentration or the availability of clean copper sites. Of the two distinct domains of adsorbed oxygen identified at room temperature on the Cu(100) surfaces, the (√ 2 × √ 2)-R45° structure reacts slightly faster with HCl than the missing row (√ 2 × 2 √ 2)-R45° O(a) structure. The results address the first stages in the formation of a copper chloride and present an interesting comparison with the HCl/O(a) reaction at Cu(110) surfaces, where oxygen also increased the extent of HCl reactions. The results emphasize the importance of the exothermic reaction to form water in the HCl/O(a) reaction on copper.

  17. XPS and FTIR spectroscopic study on microwave treated high phosphorus iron ore

    NASA Astrophysics Data System (ADS)

    Omran, Mamdouh; Fabritius, Timo; Elmahdy, Ahmed M.; Abdel-Khalek, Nagui A.; El-Aref, Mortada; Elmanawi, Abd El-Hamid

    2015-08-01

    A growing interest in microwave heating has emerged recently. Several potential microwave applications regarding minerals' processing have been investigated. This paper investigates the effect of microwave radiation on Egyptian high phosphorus iron ore. Three different iron ore samples have varying Fe2O3 and P2O5 contents and mineralogical textures were studied. A comparative study has been carried out between untreated and microwave treated iron ore. XRD and FTIR analyses showed that after microwave radiation the crystallinity of iron bearing minerals (hematite) increased, while the functional chemical groups of phosphorus bearing minerals (fluorapatite) and other gangues dissociated. High resolution XPS analyses of Fe 2p peaks showed that after microwave radiation a portion of Fe(+III) was reduced to Fe(+II). This means that after microwave radiation iron oxide (hematite, Fe3+) transformed into more magnetic phase. The results indicated that microwave radiation had a positive effect on the magnetic properties of iron oxide, through formation of ferromagnetic phases.

  18. [In situ FTIR and XPS study on selective hydrodesulfurization catalyst of FCC gasoline].

    PubMed

    Qiherima; Yuan, Hui; Zhang, Yun-hong; Li, Hui-feng; Xu, Guang-tong

    2011-07-01

    Improvement of the selectivity of hydrodesulfurization (HDS) for hydrogenation (HYD) of olefins is crucial to produce sulfur-free (S < 0.001%) gasoline from fluid catalytic-cracked (FCC) gasoline. A series of sulfided CoMo/Al2O3 catalysts with different metal loading were prepared by pore-filling impregnation. MoS2 and COMoS active phases on the surface of sulfided COMo/Al2O3 catalyst were identified and analyzed quantitatively by XPS and in-situ FTIR of adsorbed CO. The results reveal that the increase in COMoS phase on the catalyst surface improves the HDS activity and selectivity. And the HDS selectivity correlates linearly with the ratio of active site number of CoMoS and MoS2, the higher the ratio of active site number of CoMoS and MoS2, the better the HDS selectivity. In situ variable temperature FTIR analysis shows that CoMoS phase has stronger electron accepting ability than MoS2. The strong electron deficient property of CoMoS active sites is the main reason for its excellent HDS activity and selectivity. PMID:21942017

  19. An Application for Near Real-time Analysis of XPS Data

    SciTech Connect

    Lea, Alan S.; Swanson, Kenneth R.; Haack, Jereme N.; Castle, James E.; Tougaard, Sven M.; Baer, Donald R.

    2010-04-22

    Real-time analysis of x-ray photoelectron spectroscopy (XPS) data has significant potential advantages to scientists and analysts in that it has the potential to qualitatively alter the way an experiment is carried forward. As an example, immediate information about the magnitude of contamination and the layering of the surface could allow the scientist to immediately ask the next level of question and quickly re-direct the next experiment or test, even before the sample has been removed from the spectrometer. In addition to changing the nature of possible experiments, the immediate automated analysis of relatively simple procedures that an operator would normally conduct manually after the data files are saved, the report generation summarizing these analyses, and saving of this report to files with the critical metadata attached, has the potential to improve the turn-around time for data analysis, increase the sophistication of data analysis reportable to the scientist and reduce the labor involved in data analysis, resulting in significant time and cost savings.

  20. XPS study of the effect of hydrocarbon contamination on polytetrafluoroethylene (teflon) exposed to atomic oxygen

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Wydeven, Theodore; Cormia, Robert D.

    1991-01-01

    The presence of hydrocarbon contamination on the surface of polytetrafluoroethylene (PTFE) markedly affects the oxygen uptake, and hence the wettability, of this polymer when exposed to an oxygen plasma. As revealed by X-ray photoelectron spectroscopy (XPS) analysis, the oxygen-to-carbon ratio (O/C) for such a polymer can increase sharply, and correspondingly the fluorine-to-carbon ratio (F/C) can decrease sharply, at very short exposure times; at longer times, however, such changes in the O/C and F/C ratios reverse direction, and these ratios then assume values similar to those of the unexposed PTFE. The greater the extent of hydrocarbon contamination in the PTFE, the larger are the amplitudes of the 'spikes' in the O/C- and F/C-exposure time plots. In contrast, a pristine PTFE experiences a very small, monotonic increase of surface oxidation or O/C ratio with time of exposure to oxygen atoms, while the F/C ratio is virtually unchanged from that of the unexposed polymer (2.0). Unless the presence of adventitious hydrocarbon is taken into account, anomalous surface properties relating to polymer adhesion may be improperly ascribed to PTFE exposed to an oxygen plasma.

  1. Modeling the PbI2 formation in perovskite solar cells using XRD/XPS patterns

    NASA Astrophysics Data System (ADS)

    Sohrabpoor, Hamed; Elyasi, Majid; Aldosari, Marouf; Gorji, Nima E.

    2016-09-01

    The impact of prolonged irradiation and air humidity on the stability of perovskite solar cells is modeled using X-ray diffraction and X-ray photoelectron spectroscopy patterns reported in the literature. Light or air-moisture causes the formation of a thin PbI2 or oxide defective layers (in nanoscale) at the interface of perovskite/hole-transport-layer or at the junction with metallic back contact. This thin layer blocks the carrier transport/passivation at the interfaces and cause degradation of device parameters. Variation in thickness of defective layers, changes the XRD and XPS peaks. This allows detection and estimation of the type, crystallinity and thickness of the defective layer. A simple model is developed here to extract the thickness of such thin defective layers formed in nanometer scale at the back region of several perovskite devices. Based on this information, corrected energy band diagram of every device before and after degradation/aging is drawn and discussed in order to obtain insight into the carrier transport and charge collection at the barrier region. In addition, graphene contacted perovskite devices are investigated showing that honey-comb network of graphene contact reduces the effect of aging leading to formation of a thinner defective layer at the perovskite surface compared to perovskite devices with conventional inorganic contacts i.e. Au, Al.

  2. Interfacial chemistry of a perfluoropolyether lubricant studied by XPS and TDS

    NASA Technical Reports Server (NTRS)

    Herrera-Fierro, Pilar C.; Jones, William R., Jr.; Pepper, Stephen V.

    1992-01-01

    The interfacial chemistry of Fomblin Z25, a commercial perfluoropolyether used as lubricant for space applications, with different metallic surfaces: 440C steel, gold and aluminum was studied. Thin layers of Fomblin Z25 were evaporated onto the oxide-free substrates and the interfacial chemistry studied using XPS and TDS. The reactions were induced by heating the substrate and by rubbing the substrate with a steel ball. Gold was found to be completely unreactive towards Fomblin at any temperature. Reaction at room temperature was observed only in the case of the aluminum substrate, the most reactive towards Fomblin Z25 of the substrates studied. It was necessary to heat the 440C steel substrate to 190 degree C to induce decomposition of the fluid. The degradation of the fluid was indicated by the formation of a debris layer at the interface. This debris layer, composed of inorganic and organic reaction products, when completely formed, passivated the surface from further attack to the Fromblin on top. The tribologically induced reactions on 440C steel formed a debris layer of similar chemical characteristics to the thermally induced layer. In all cases, the degradation reaction resulted in preferential consumption of the difluoroformyl carbon (-OCF2O-).

  3. XPS for probing the dynamics of surface voltage and photovoltage in GaN

    NASA Astrophysics Data System (ADS)

    Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2014-12-01

    We describe application of two different data gathering techniques of XPS for probing the dynamics of surface voltage and surface photovoltage (SPV) developed in microseconds to seconds time-domain, in addition to the conventional steady-state measurements. For the longer (seconds to milliseconds) regime, capturing the data in the snapshot fashion is used, but for the faster one (down to microseconds), square wave (SQW) electrical pulses at different frequencies are utilized to induce and probe the dynamics of various processes causing the surface voltage, including the SPV, via the changes in the peak positions. The frequency range covers anywhere from 10-3 to 105 Hz for probing changes due to charging (slow), dipolar (intermediate), and electronic (fast) processes associated with the external stresses imposed. We demonstrate its power by application to n- and p-GaN, and discuss the chemical/physical information derived thereof. In addition, the method allows us to decompose and identify the peaks with respect to their charging nature for a composite sample containing both n- and p-GaN moieties.

  4. X-Ray Photoelectron Spectroscopy (XPS) Applications Using Microfocused X-Rays

    NASA Astrophysics Data System (ADS)

    Chaney, Robert; Cormia, Robert; Siordia, Ruth

    1986-08-01

    A focusing quartz crystal monochromator system. has been developed that provides a bright X-ray spot at 1486.6ev. The X-ray spot size may he varied from one-hundred fifty (150) to one-thousand (1000) microns in four (4) steps. The X-ray system is combined with a high. performance electron lens that collects greater than five (5) percent of the photoemitted electrons and passes them into a hemispherical capacitor energy analyzer. The electrons are detected at the exit plane with a two (2) dimensional position sensitivity detector. Using this system, XPS has been carried out on a wide variety of practical samples. We will provide a brief review of the system, design followed by examples of the solution to unique problems. Samples which have been CLosen for discussion include: Crash Zone on a Winchester Disk An interocular Lens . Single 5 micron Carbon. Fiber Plasma Modified Polymeric Say The unique benefits of a focused. source with high energy resolution will also be discussed.

  5. XPS characterization of (copper-based) coloured stains formed on limestone surfaces of outdoor Roman monuments

    PubMed Central

    2012-01-01

    Limestone basements holding bronzes or other copper alloys artefacts such as sculptures, decorations and dedicatory inscriptions are frequently met both in modern and ancient monuments. In outdoor conditions, such a combination implies the corrosion products of the copper based alloy, directly exposed to rainwater, will be drained off and migrate through the porous surfaces, forming stains of different colours and intensities, finally causing the limestone structures to deteriorate. In this work we have analysed samples from two modern limestone monuments in Rome, the Botticino surfaces of the ‘Vittoriano’ (by G.Sacconi, 1885-1911- Piazza Venezia) and the travertine basement of the ‘Statua dello Studente’ (by A.Cataldi, 1920- University city, La Sapienza), and focussed our investigation on the chemical composition of the copper-stained zones using XPS (X-ray Photoelectron Spectroscopy) as a surface-specific technique. Based on observations reporting on the structure and bonding at the calcite surfaces we have identified copper complexes and mixed calcium/copper carbonates associated with the stains, as well as the chemical state of other elements therein included, and related the compositional changes with differences in chromatic characteristics and sampling locations. PMID:22594435

  6. Oxygen nonstoichiometry of tetragonal La2-xSr(x)CuO4-δ (x = 0.15-1.2) and in situ XPS studies at elevated temperatures.

    PubMed

    Alyoshin, V A; Romanova, I P; Mikhailova, D; Oswald, S; Senyshyn, A; Ehrenberg, H

    2010-12-30

    The peculiarities of oxygen nonstoichiometry (δ) in tetragonal La(2-x)Sr(x)CuO(4-δ) solid solution with x(Sr) = 0.15-1.2 were studied by XRD, NPD, in situ high-temperature XPS, and chemical analysis. Temperature dependences of oxygen nonstoichiometry, δ = δ(T), were obtained for different Sr contents at 1 bar of O(2). Two types of charge compensation during replacement of lanthanum by strontium are discussed: an increase of the average copper oxidation state and a formation of oxygen vacancies. The average copper oxidation state V(Cu) exhibits a maximum of 2.32 at x(Sr) = 0.6, while δ increases with x(Sr). Oxygen vacancies are unambiguously located on the 4c site ({CuO(2)} plane) for compositions with different strontium contents, which electronic state is described by the O 2p core electron peak at about 531 eV. Thermal stability of the solid solution in a vacuum is associated with the extraction of practically the entire oxygen from CuO(2) layers and the formation of Cu(+) at least in the near-surface region. The higher average copper oxidation state after synthesis in the Sr-rich phases in comparison with the Sr-poor compositions prevents oxygen removal and the formation of Cu(+) and, therefore, stabilizes the structure during heating in a vacuum. PMID:21133400

  7. Fluorocarbon assisted atomic layer etching of SiO{sub 2} using cyclic Ar/C{sub 4}F{sub 8} plasma

    SciTech Connect

    Metzler, Dominik; Oehrlein, Gottlieb S.; Bruce, Robert L.; Engelmann, Sebastian; Joseph, Eric A.

    2014-03-15

    The authors demonstrate atomic layer etching of SiO{sub 2} using a steady-state Ar plasma, periodic injection of a defined number of C{sub 4}F{sub 8} molecules, and synchronized plasma-based Ar{sup +} ion bombardment. C{sub 4}F{sub 8} injection enables control of the deposited fluorocarbon (FC) layer thickness in the one to several Ångstrom range and chemical modification of the SiO{sub 2} surface. For low energy Ar{sup +} ion bombardment conditions, the physical sputter rate of SiO{sub 2} vanishes, whereas SiO{sub 2} can be etched when FC reactants are present at the surface. The authors have measured for the first time the temporal variation of the chemically enhanced etch rate of SiO{sub 2} for Ar{sup +} ion energies below 30 eV as a function of fluorocarbon surface coverage. This approach enables controlled removal of Ångstrom-thick SiO{sub 2} layers. Our results demonstrate that development of atomic layer etching processes even for complex materials is feasible.

  8. The VMI study on angular distribution of ejected electrons from Eu 4f76p1/26d autoionizing states

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Shen, Li; Dong, Cheng; Dai, Chang-Jian

    2015-10-01

    The combination of a velocity mapping imaging technique and mathematical transformation is adopted to study the angular distribution of electrons ejected from the Eu 4f76p1/26d autoionizing states, which are excited with a three-step excitation scheme via different Eu 4f76s6d 8 DJ (J = 5/2, 7/2, and 9/2) intermediate states. In order to determine the energy dependence of angular distribution of the ejected electrons, the anisotropic parameters are measured in the spectral profile of the 6p1/26d autoionizing states by tuning the wavelength of the third-step laser across the ionic resonance lines of the Eu 6s+ → 6p+. The configuration interaction is discussed by comparing the angular distributions of ejected electrons from the different states. The present study reveals the profound variations of anisotropic parameters in the entire region of autoionization resonance, highlighting the complicated nature of the autoionization process for the lowest member of 6p1/26d autoionization series. Project supported by the National Natural Science Foundation of China (Grant No. 11174218).

  9. A DFT+U study on the contribution of 4f electrons to oxygen vacancy formation and migration in Ln-doped CeO2.

    PubMed

    Alaydrus, M; Sakaue, M; Kasai, H

    2016-05-14

    A rare earth doped form of ceria (CeO2) is of interest as a potential candidate for solid oxide fuel cells (SOFCs) because of its relatively high oxygen ion conductivity at temperatures below 600 °C. At the present time, computational chemistry has reached a certain maturity which allows the prediction of materials properties that are difficult to observe experimentally. However, understanding of the roles of dopants in the oxygen ion conduction in CeO2 is still incomplete for quantitatively reliable analysis due to the strong electron correlation of 4f electrons. In this study, density functional theory calculations with Hubbard U corrections are used to discuss ionic/covalent interactions in rare-earth-doped CeO2 and their consequences to oxygen ion conduction. This study suggests that the variable occupancy of empty 4f orbitals is important typically for early Ln elements to produce the covalent interactions that essentially affect the formation and migration of oxygen vacancies. This finding is important in understanding the factors responsible for oxygen ion diffusion in doped CeO2. PMID:27108893

  10. Investigation of the electronic structures of organolanthanide sandwich complex anions by photoelectron spectroscopy: 4f orbital contribution in the metal-ligand interaction.

    PubMed

    Hosoya, Natsuki; Yada, Keizo; Masuda, Tomohide; Nakajo, Erika; Yabushita, Satoshi; Nakajima, Atsushi

    2014-05-01

    The electronic structures of lanthanide (Ln) ions sandwiched between 1,3,5,7-cyclooctatetraene (COT), Ln(COT)2(-), have been investigated by anion photoelectron spectroscopy. Complexes of 12 Ln atoms were investigated (excluding promethium (Pm), europium (Eu), and ytterbium (Yb)). The 213 nm photoelectron (PE) spectra of Ln(COT)2(-) exhibit two peaks assignable to the highest occupied molecular orbital (HOMO; e2u) and the next HOMO (HOMO-1; e2g) approximately at 2.6 and 3.6 eV, respectively, and their energy gap increases as the central metal atom progresses from lanthanum (La) to lutetium (Lu). Since lanthanide contraction shortens the distance between the Ln atom and the COT ligands, the widening energy gap represents the destabilization of the e2u orbital as well as the stabilization of the e2g orbital. Evidence for 4f orbital contribution in the metal-ligand interaction has been revealed by the Ln atom dependence in which the same e2u orbital symmetry enables an interaction between the 4f orbital of Ln atoms and the π orbital of COT. PMID:24742246

  11. Magnetic ordering of hyperfine-coupled nuclear and 4f-electron moments in the clathrate compound Pr3Pd20Ge6

    NASA Astrophysics Data System (ADS)

    Iwakami, O.; Namisashi, Y.; Abe, S.; Matsumoto, K.; Ano, G.; Akatsu, M.; Mitsumoto, K.; Nemoto, Y.; Takeda, N.; Goto, T.; Kitazawa, H.

    2014-09-01

    Complex ac susceptibility, χ =χ'-iχ'', measurements of the clathrate compound Pr3Pd20Ge6 were performed in static fields up to 10 mT for H ∥[001] and at temperatures down to 500 μK. Praseodymium (Pr) nuclear magnetic moments at the 8c site, where quadrupole moments of 4f electrons order at TQ1=250 mK, were found to order antiferromagnetically at 9 mK, as shown by a peak in χ' and a substantial increase in thermal relaxation time. The large enhancement factor (1+K8c) obtained by calculation of the hyperfine-enhanced nuclear susceptibility of Pr at the 8c site accounts for the high transition temperature of Pr nuclear magnetic moments and the large χ' below 30 mK. From analysis of the crystalline electric field and the mean-field approximation, we conclude that a χ peak at 77 mK can be ascribed to an antiferromagnetic ordering of magnetic moments of 4f electrons at the 4a site. We found that nuclear and f-electron moments order separately on two sublattices in this compound. The temperature and magnetic field dependence of χ' and χ'' between 30 and 60 mK are discussed in terms of dissipation phenomena.

  12. Dual-core antiresonant hollow core fibers.

    PubMed

    Liu, Xuesong; Fan, Zhongwei; Shi, Zhaohui; Ma, Yunfeng; Yu, Jin; Zhang, Jing

    2016-07-25

    In this work, dual-core antiresonant hollow core fibers (AR-HCFs) are numerically demonstrated, based on our knowledge, for the first time. Two fiber structures are proposed. One is a composite of two single-core nested nodeless AR-HCFs, exhibiting low confinement loss and a circular mode profile in each core. The other has a relatively simple structure, with a whole elliptical outer jacket, presenting a uniform and wide transmission band. The modal couplings of the dual-core AR-HCFs rely on a unique mechanism that transfers power through the air. The core separation and the gap between the two cores influence the modal coupling strength. With proper designs, both of the dual-core fibers can have low phase birefringence and short modal coupling lengths of several centimeters. PMID:27464191

  13. Carbonaceous matter in peridotites and basalts studied by XPS, SALI, and LEED

    SciTech Connect

    Tingle, T.N. SRI International, Menlo Park, CA ); Mathez, E.A. ); Hochella, M.F. Jr. )

    1991-05-01

    Carbonaceous matter in peridotite xenoliths and basalt from the Hualalai Volcano, in a basalt glass collected directly from an active lava lake on the east rift of Kilauea, in garnet and diopside megacrysts from the Jagersfontein kimberlite, and in gabbros from the Stillwater and Bushveld Complexes has been studied by X-ray photoelectron spectroscopy (XPS), thermal-desorption surface analysis by laser ionization (SALI), and low-energy electron diffraction (LEED). The basalt and two of the four xenoliths from Hualalai and both Jagersfontein megacrysts yielded trace quantities ({le}10 nanomoles) of organic compounds on heating to 700C. Organics were not detected in the rocks from the layered intrusions, and neither carbonaceous matter nor organics were detected in the glass from the lava lake. Where detected, organics appear to be associated with carbonaceous films on microcrack surfaces. Carbonaceous matter exists as films less than a few nm thick and particles up to 20 {mu}m across, both of which contain elements expected to be present in significant quantities in magmatic vapors, namely Si, alkalis, halogens, N, and transition metals. LEED studies suggest that the carbonaceous films are amorphous. The data suggest two possible mechanisms for the formation of the organics. One is that they are a product of abiotic heterogeneous catalysis of volcanic gas on new, chemically active mineral surfaces formed by fracturing during cooling. Alternatively, organics may have been assimilated into the volcanic gases prior to eruption and then deposited on cracks formed during eruption and cooling. In any case, there is no evidence to suggest that the organics represent laboratory or field biogenic contamination.

  14. XPS investigations of tribolayers formed on TiN and (Ti,Re)N coatings

    NASA Astrophysics Data System (ADS)

    Oktay, Serkan; Kahraman, Zafer; Urgen, Mustafa; Kazmanli, Kursat

    2015-02-01

    TiN and (Ti,Re)N coatings were deposited on high-speed-steel substrates by a hybrid coating system composed of cathodic arc PVD and magnetron sputtering techniques. In order to keep rhenium content low (8 ± 1.9 at.%) in the coating, magnetron sputtering technique was utilized to evaporate rhenium. The (Ti,Re)N coating consisted of TiN and ReNx (x > 1.33) phases. The hardness of TiN and (Ti,Re)N were 31 GPa and 29 GPa (± 2 GPa), respectively. Tribological behaviors of the samples were tested against Al2O3 balls at 21 °C (RT) and 150 °C (HT) by reciprocating wear technique. The tribolayers were analyzed by XPS technique. Friction coefficients of TiN were 0.56, 0.35 for 21 °C and 150 °C tests, respectively. Rhenium addition to TiN drastically dropped the friction coefficients to 0.22 and 0.17 for RT and HT samples. Rhenium addition also improved the wear resistance of the coating at both test temperatures. For TiN, main oxide component of the tribolayers was Ti2O3 for RT tests and TiO2 for HT tests. The oxide layer formed on (Ti,Re)N were the mixture of TiO2, Tisbnd Osbnd N, ReO2 and Re2O7 for both test temperatures. Re2O7 provided very low friction coefficient to (Ti,Re)N. The findings are consistent with the crystal chemistry approach.

  15. Experimental (XAS STEM TPR and XPS) and Theoretical (DFT) Characterization of Supported Rhenium Catalysts

    SciTech Connect

    S Bare; S Kelly; F Vila; D Boldingh; E Karapetrova; J Kas; G Mickelson; F Modica; N Yang; J Rehr

    2011-12-31

    A high surface area supported Re-based catalyst, fundamental to heterogeneous catalysis, is studied in the oxidic and reduced states using a combination of experimental (XAFS, STEM, TPR, and XPS) and theoretical (DFT and X-ray spectroscopy simulations) approaches. In the calcined dried catalyst, the Re species is present as an isolated trioxo(oxoaluminate) Re(VII) species. The temperature at which the Re undergoes reduction is a function of the hydrogen partial pressure and temperature ramp rate, but the maximum rate of reduction occurs in the range 300-400 C. Following reduction at 500 or 700 C in dry hydrogen, the Re is present as a mixture of species: unreduced trioxo(oxoaluminate) Re(VII) species, Re nanoclusters, and isolated Re atoms. By using a multifaceted approach, it is apparent that the majority species is an isolated Re adatom bound to the alumina support. DFT calculations identify several likely adsorption sites for these Re adatoms on the [110] surface of {gamma}-Al{sub 2}O{sub 3}. The final extended X-ray absorption fine structure (EXAFS) model taking into account these three species is used to identify the dominant adsorption site for Re on the alumina surface. FEFF8 X-ray absorption near-edge spectroscopy (XANES) calculations of unsupported and alumina-supported Re nanoclusters provide interpretation of the shape and edge position of the Re L{sub 3}-edge XANES after reduction. The presence of moisture during reduction stronly affects the mobility of the Re on the alumina leading to agglomeration. Subsequent air exposure of a reduced catalyst readily reoxidizes the reduced Re. The power of using a combination of analysis tools provides insight into the behavior of dispersed Re on supported alumina under oxidizing and reducing conditions relevant to heterogeneous catalysis.

  16. In situ XPS investigation of Pt(Sn)/Mg(Al)O catalysts during ethane dehydrogenation experiments

    NASA Astrophysics Data System (ADS)

    Virnovskaia, Anastasia; Jørgensen, Sissel; Hafizovic, Jasmina; Prytz, Øystein; Kleimenov, Evgueni; Hävecker, Michael; Bluhm, Hendrik; Knop-Gericke, Axel; Schlögl, Robert; Olsbye, Unni

    2007-01-01

    Calcined hydrotalcite with or without added metal (Mg(Al)O, Pt/Mg(Al)O and Pt,Sn/Mg(Al)O) have been investigated with in situ X-ray photoelectron spectroscopy (XPS) during ethane dehydrogenation experiments. The temperature in the analysis chamber was 450 °C and the gas pressure was in the range 0.3-1 mbar. Depth profiling of calcined hydrotalcite and platinum catalysts under reaction, oxidation and in hydrogen-water mixture was performed by varying the photon energy, covering an analysis depth of 10-21 Å. It was observed that the Mg/Al ratio in the Mg(Al)O crystallites does not vary significantly in the analysis depth range studied. This result indicates that Mg and Al are homogeneously distributed in the Mg(Al)O crystallites. Catalytic tests have shown that the initial activity of a Pt,Sn/Mg(Al)O catalyst increases during an activation period consisting of several cycles of reduction-dehydrogenation-oxidation. The Sn/Mg ratio in a Pt,Sn/Mg(Al)O catalyst was followed during several such cycles, and was found to increase during the activation period, probably due to a process where tin spreads over the carrier material and covers an increasing fraction of the Mg(Al)O surface. The results further indicate that spreading of tin occurs under reduction conditions. A PtSn 2 alloy was studied separately. The surface of the alloy was enriched in Sn during reduction and reaction conditions at 450 °C. Binding energies were determined and indicated that Sn on the particle surface is predominantly in an oxidised state under reaction conditions, while Pt and a fraction of Sn is present as a reduced Pt-Sn alloy.

  17. XPS determination of Mn oxidation states in Mn (hydr)oxides

    NASA Astrophysics Data System (ADS)

    Ilton, Eugene S.; Post, Jeffrey E.; Heaney, Peter J.; Ling, Florence T.; Kerisit, Sebastien N.

    2016-03-01

    Hydrous manganese oxides are an important class of minerals that help regulate the geochemical redox cycle in near-surface environments and are also considered to be promising catalysts for energy applications such as the oxidation of water. A complete characterization of these minerals is required to better understand their catalytic and redox activity. In this contribution an empirical methodology using X-ray photoelectron spectroscopy (XPS) is developed to quantify the oxidation state of hydrous multivalent manganese oxides with an emphasis on birnessite, a layered structure that occurs commonly in soils but is also the oxidized endmember in biomimetic water-oxidation catalysts. The Mn2p3/2, Mn3p, and Mn3s lines of near monovalent Mn(II), Mn(III), and Mn(IV) oxides were fit with component peaks; after the best fit was obtained the relative widths, heights and binding energies of the components were fixed. Unknown multivalent samples were fit such that binding energies, intensities, and peak-widths of each oxidation state, composed of a packet of correlated component peaks, were allowed to vary. Peak-widths were constrained to maintain the difference between the standards. Both average and individual mole fraction oxidation states for all three energy levels were strongly correlated, with close agreement between Mn3s and Mn3p analyses, whereas calculations based on the Mn2p3/2 spectra gave systematically more reduced results. Limited stoichiometric analyses were consistent with Mn3p and Mn3s. Further, evidence indicates the shape of the Mn3p line was less sensitive to the bonding environment than that for Mn2p. Consequently, fitting the Mn3p and Mn3s lines yielded robust quantification of oxidation states over a range of Mn (hydr)oxide phases. In contrast, a common method for determining oxidation states that utilizes the multiplet splitting of the Mn3s line was found to be not appropriate for birnessites.

  18. Synthesis, structures, and magnetic properties of a family of 3d-4f [Na2Fe6Ln2] complexes (Ln = Y, Gd and Dy): effect of ligands on the connection of inorganic subunits.

    PubMed

    Zhou, Qi; Yang, Fen; Liu, Dan; Peng, Yu; Li, Guanghua; Shi, Zhan; Feng, Shouhua

    2013-01-28

    A family of 3d-4f heterometallic compounds [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(HL)(4)(CH(3)O)(4)(PhCO(2))(6)] (1, H(4)L = 2-{[(2-hydroxy-3-methoxyphenyl)methylene]amino}-2-(hydroxymethyl)-1,3-propanediol), [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(H(2)O)] (2, H(3)L' = (E)-2-ethyl-2-(2-hydroxy-3-methoxybenzylideneamino)propane-1,3-diol), [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(Bu(t)CO(2))(6)] (3) [Na(2)Fe(III)(6)Y(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(H(2)O)] (4), and [Na(2)Fe(III)(6)Gd(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(CH(3)OH)(2)] (5) have been prepared using Schiff-base ligands, trinuclear iron precursor complexes, azides and lanthanide nitrates as reactants. In compounds 1 and 2, the structure of the [Na(2)Fe(III)(6)Dy(III)(2)] cluster forms a couple of cis,trans-isomers with substitution of methyl for a free hydroxyl group which belongs to the Schiff-base ligand. When the pivalates are employed instead of bulkier benzoates, the trans-[Na(2)Fe(III)(6)Dy(III)(2)] clusters act as network nodes in the formation of rhombic grid-like layered structures in compound 2. Compounds 2, 4 and 5 have similar metallic cores, only with different crystal solvent molecules. The magnetic measurements on all the compounds indicate dominant antiferromagnetic interactions between the metal centers. PMID:23114511

  19. Heteropentanuclear Oxalato-Bridged nd-4f (n=4, 5) Metal Complexes with NO Ligand: Synthesis, Crystal Structures, Aqueous Stability and Antiproliferative Activity.

    PubMed

    Kuhn, Paul-Steffen; Cremer, Laura; Gavriluta, Anatolie; Jovanović, Katarina K; Filipović, Lana; Hummer, Alfred A; Büchel, Gabriel E; Dojčinović, Biljana P; Meier, Samuel M; Rompel, Annette; Radulović, Siniša; Tommasino, Jean Bernard; Luneau, Dominique; Arion, Vladimir B

    2015-09-21

    A series of heteropentanuclear oxalate-bridged Ru(NO)-Ln (4d-4f) metal complexes of the general formula (nBu4N)5[Ln{RuCl3(μ-ox)(NO)}4], where Ln=Y (2), Gd (3), Tb (4), Dy (5) and ox=oxalate anion, were obtained by treatment of (nBu4N)2[RuCl3(ox)(NO)] (1) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1, 2, and 5 were in addition analyzed by X-ray crystallography, 1 by Ru K-edge XAS and 1 and 2 by (13)C NMR spectroscopy. X-ray diffraction showed that in 2 and 5 four complex anions [RuCl3(ox)(NO)](2-) are coordinated to Y(III) and Dy(III), respectively, with formation of [Ln{RuCl3(μ-ox)(NO)}4](5-) (Ln=Y, Dy). While Y(III) is eight-coordinate in 2, Dy(III) is nine-coordinate in 5, with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu4N(+) ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium-lanthanide complexes 2-5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC-5) and compared with those obtained for the previously reported Os(NO)-Ln (5d-4f) analogues (nBu4N)5[Ln{OsCl3(ox)(NO)}4] (Ln=Y (6), Gd (7), Tb (8), Dy (9)). Complexes 2-5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d-4f metal complexes 6-9 in terms of IC50 values. The highest antiproliferative activity with IC50 values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP-MS data, indicating five- to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells. PMID:26260662

  20. Heteropentanuclear Oxalato-Bridged nd–4f (n=4, 5) Metal Complexes with NO Ligand: Synthesis, Crystal Structures, Aqueous Stability and Antiproliferative Activity

    PubMed Central

    Kuhn, Paul-Steffen; Cremer, Laura; Gavriluta, Anatolie; Jovanović, Katarina K; Filipović, Lana; Hummer, Alfred A; Büchel, Gabriel E; Dojčinović, Biljana P; Meier, Samuel M; Rompel, Annette; Radulović, Siniša; Tommasino, Jean Bernard; Luneau, Dominique; Arion, Vladimir B

    2015-01-01

    A series of heteropentanuclear oxalate-bridged Ru(NO)-Ln (4d–4f) metal complexes of the general formula (nBu4N)5[Ln{RuCl3(μ-ox)(NO)}4], where Ln=Y (2), Gd (3), Tb (4), Dy (5) and ox=oxalate anion, were obtained by treatment of (nBu4N)2[RuCl3(ox)(NO)] (1) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1, 2, and 5 were in addition analyzed by X-ray crystallography, 1 by Ru K-edge XAS and 1 and 2 by 13C NMR spectroscopy. X-ray diffraction showed that in 2 and 5 four complex anions [RuCl3(ox)(NO)]2− are coordinated to YIII and DyIII, respectively, with formation of [Ln{RuCl3(μ-ox)(NO)}4]5− (Ln=Y, Dy). While YIII is eight-coordinate in 2, DyIII is nine-coordinate in 5, with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu4N+ ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium-lanthanide complexes 2–5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC-5) and compared with those obtained for the previously reported Os(NO)-Ln (5d–4f) analogues (nBu4N)5[Ln{OsCl3(ox)(NO)}4] (Ln=Y (6), Gd (7), Tb (8), Dy (9)). Complexes 2–5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d–4f metal complexes 6–9 in terms of IC50 values. The highest antiproliferative activity with IC50 values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP-MS data, indicating five- to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells. PMID:26260662

  1. Effects of D-4F on Vasodilation and Vessel Wall Thickness in Hypercholesterolemic LDL Receptor Null and LDL receptor/ApoA-I Double Knockout Mice on Western Diet

    PubMed Central

    Ou, Jingsong; Wang, Jingli; Xu, Hao; Ou, Zhijun; Sorci-Thomas, Mary G.; Jones, Deron W.; Signorino, Paul; Densmore, John C.; Kaul, Sushma; Oldham, Keith T.; Pritchard, Kirkwood A.

    2005-01-01

    Previously we showed L-4F, a novel apolipoprotein A-I (apoA-I) mimetic, improved vasodilation in two dissimilar models of vascular disease; hypercholesterolemic low-density lipoprotein (LDL) receptor null (Ldlr −/−) mice and transgenic sickle cell disease mice. Here we determine the mechanisms by which D-4F improves vasodilation and arterial wall thickness in hypercholesterolemic Ldlr −/− mice and Ldlr −/−/apoA-I null (apoA-I −/−), double knockout mice. Ldlr −/− and Ldlr −/−/apoA-I −/− mice were fed western diet (WD) ± D-4F. Oral D-4F restored endothelium- and eNOS-dependent vasodilation in direct relationship to duration of treatments and reduced wall thickness in as little as 2 weeks in vessels with pre-existing disease in Ldlr −/− mice. D-4F had no effect on total or HDL cholesterol concentrations but reduced proinflammatory HDL levels. D-4F had no effect on plasma myeloperoxidase (MPO) concentrations but reduced MPO association with apoA-I as well as 3-nitrotyrosine in apoA-I. D-4F increased endothelium- and eNOS-dependent vasodilation in Ldlr −/−/apoA-I −/− mice but did not reduce wall thickness as it had in Ldlr −/− mice. Vascular endothelial cells were treated with 22-hydroxycholesterol (22-OHC) ± L-4F. 22-OHC decreased nitric oxide (•NO) and increased superoxide anion (O2 •−) production and increased ABCA-1 and collagen expression. L-4F restored •NO and O2 •− balance, had little effect on ABCA-1 expression but reduced collagen expression. These data demonstrate that although D-4F restores vascular endothelial cell and eNOS function to increase vasodilation, HDL containing apoA-I, or at least some critical concentration of the anti-atherogenic lipoprotein, is required for D-4F to decrease vessel wall thickness. PMID:16224061

  2. CYP4F Enzymes Are the Major Enzymes in Human Liver Microsomes That Catalyze the O-Demethylation of the Antiparasitic Prodrug DB289 [2,5-Bis(4-amidinophenyl)furan-bis-O-methylamidoxime

    PubMed Central

    Wang, Michael Zhuo; Saulter, Janelle Y.; Usuki, Etsuko; Cheung, Yen-Ling; Hall, Michael; Bridges, Arlene S.; Loewen, Greg; Parkinson, Oliver T.; Stephens, Chad E.; Allen, James L.; Zeldin, Darryl C.; Boykin, David W.; Tidwell, Richard R.; Parkinson, Andrew; Paine, Mary F.; Hall, James Edwin

    2007-01-01

    DB289 [2,5-bis(4-amidinophenyl)furan-bis-O-methylamidoxime] is biotransformed to the potent antiparasitic diamidine DB75 [2,5-bis(4-amidinophenyl) furan] by sequential oxidative O-demethylation and reductive N-dehydroxylation reactions. Previous work demonstrated that the N-dehydroxylation reactions are catalyzed by cytochrome b5/NADH-cytochrome b5 reductase. Enzymes responsible for catalyzing the DB289 O-demethylation pathway have not been identified. We report an in vitro metabolism study to characterize enzymes in human liver microsomes (HLMs) that catalyze the initial O-demethylation of DB289 (M1 formation). Potent inhibition by 1-aminobenzotriazole confirmed that M1 formation is catalyzed by P450 enzymes. M1 formation by HLMs was NADPH-dependent, with a Km and Vmax of 0.5 μM and 3.8 nmol/min/mg protein, respectively. Initial screening showed that recombinant CYP1A1, CYP1A2, and CYP1B1 were efficient catalysts of M1 formation. However, none of these three enzymes was responsible for M1 formation by HLMs. Further screening showed that recombinant CYP2J2, CYP4F2, and CYP4F3B could also catalyze M1 formation. An antibody against CYP4F2, which inhibited both CYP4F2 and CYP4F3B, inhibited 91% of M1 formation by HLMs. Two inhibitors of P450-mediated arachidonic acid metabolism, HET0016 (N-hydroxy-N′-(4-n-butyl-2-methylphenyl)formamidine) and 17-octadecynoic acid, effectively inhibited M1 formation by HLMs. Inhibition studies with ebastine and antibodies against CYP2J2 suggested that CYP2J2 was not involved in M1 formation by HLMs. Additionally, ketoconazole preferentially inhibited CYP4F2, but not CYP4F3B, and partially inhibited M1 formation by HLMs. We conclude that CYP4F enzymes (e.g., CYP4F2, CYP4F3B) are the major enzymes responsible for M1 formation by HLMs. These findings indicate that, in human liver, members of the CYP4F subfamily biotransform not only endogenous compounds but also xenobiotics. PMID:16997912

  3. Initial stages of oxide formation on the Zr surface at low oxygen pressure: An in situ FIM and XPS study.

    PubMed

    Bespalov, I; Datler, M; Buhr, S; Drachsel, W; Rupprechter, G; Suchorski, Y

    2015-12-01

    An improved methodology of the Zr specimen preparation was developed which allows fabrication of stable Zr nanotips suitable for FIM and AP applications. Initial oxidation of the Zr surface was studied on a Zr nanotip by FIM and on a polycrystalline Zr foil by XPS, both at low oxygen pressure (10(-8)-10(-7)mbar). The XPS data reveal that in a first, fast stage of oxidation, a Zr suboxide interlayer is formed which contains three suboxide components (Zr(+1), Zr(+2) and Zr(+3)) and is located between the Zr surface and a stoichiometric ZrO2 overlayer that grows in a second, slow oxidation stage. The sole suboxide layer has been observed for the first time at very early states of the oxidation (oxygen exposure ≤ 4L). The Ne(+) FIM observations are in accord with a two stage process of Zr oxide formation. PMID:25766998

  4. Location and Visualization of Working p-n and/or n-p Junctions by XPS.

    PubMed

    Copuroglu, Mehmet; Caliskan, Deniz; Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2016-01-01

    X-ray photoelectron spectroscopy (XPS) is used to follow some of the electrical properties of a segmented silicon photodetector, fabricated in a p-n-p configuration, during operation under various biasing configurations. Mapping of the binding energy position of Si2p reveals the shift in the position of the junctions with respect to the polarity of the DC bias applied. Use of squared and triangular shaped wave excitations, while recording XPS data, allows tapping different electrical properties of the device under normal operational conditions, as well as after exposing parts of it to harsh physical and chemical treatments. Unique and chemically specific electrical information can be gained with this noninvasive approach which can be useful especially for localized device characterization and failure analyses. PMID:27582318

  5. Location and Visualization of Working p-n and/or n-p Junctions by XPS

    PubMed Central

    Copuroglu, Mehmet; Caliskan, Deniz; Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2016-01-01

    X-ray photoelectron spectroscopy (XPS) is used to follow some of the electrical properties of a segmented silicon photodetector, fabricated in a p-n-p configuration, during operation under various biasing configurations. Mapping of the binding energy position of Si2p reveals the shift in the position of the junctions with respect to the polarity of the DC bias applied. Use of squared and triangular shaped wave excitations, while recording XPS data, allows tapping different electrical properties of the device under normal operational conditions, as well as after exposing parts of it to harsh physical and chemical treatments. Unique and chemically specific electrical information can be gained with this noninvasive approach which can be useful especially for localized device characterization and failure analyses. PMID:27582318

  6. Polymer coatings on conductive polypyrroles surface characterization by XPS, ToFSIMS, inverse gas chromatography and AFM

    SciTech Connect

    Chehimi, M.M.; Abel, M.; Delamar, M.; Watts, J.F.; Zhdan, P.A.

    1996-01-01

    The study of PMMA adsorption on some conducting polypyrroles (PPys) using a variety of surface analytical techniques is reported. PMMA adsorption was monitored by X-ray photoelectron spectroscopy (XPS), time of flight secondary ion mass spectroscopy (ToF-SIMS) and inverse gas chromatography (IGC). XPS and ToF-SIMS permit to determine the surface composition of PMMA-coated PPy surfaces vs the solvent nature, temperature and the PPy dopant anion. Both techniques show that acid-base interactions may govern PMMA adsorption. IGC was used to determine the coating morphology by monitoring the surface energy of the coated PPy powders. It is suggested that homogeneity of PMMA coatings increases with decreasing solvent power. Preliminary atomic force microscopy (AFM) results on PMMA films cast on flat PPy surfaces confirm the IGC observation. {copyright} {ital 1996 American Institute of Physics.}

  7. XPS study of the Al/SiO2 interface viewed from the SiO2 side

    NASA Technical Reports Server (NTRS)

    Hecht, M. H.; Grunthaner, F. J.; Maserjian, J.

    1984-01-01

    The first nondestructive measurement of the chemical and physical characteristics of the interface between bulk SiO2 and thick aluminum films is presented. Both X-ray photoelectron spectroscopy (XPS) and electrical measurements of unannealed resistively evaporated Al films on thermal SiO2 indicate an atomically abrupt interface. Postmetallization annealing (PMA) at 450 C induces reduction of the SiO2 by the aluminum, resulting in the layer ordering SiO2/Al2O3/Si/Al. The XPS measurement is performed from the SiO2 side after removal of the Si substrate after etching with XeF2 gas and thinning of the SiO2 layer with HF:ETOH. This represents a powerful new approach to the study of metal-insulator and other interfaces.

  8. Initial stages of oxide formation on the Zr surface at low oxygen pressure: An in situ FIM and XPS study

    PubMed Central

    Bespalov, I.; Datler, M.; Buhr, S.; Drachsel, W.; Rupprechter, G.; Suchorski, Y.

    2015-01-01

    An improved methodology of the Zr specimen preparation was developed which allows fabrication of stable Zr nanotips suitable for FIM and AP applications. Initial oxidation of the Zr surface was studied on a Zr nanotip by FIM and on a polycrystalline Zr foil by XPS, both at low oxygen pressure (10−8–10−7 mbar). The XPS data reveal that in a first, fast stage of oxidation, a Zr suboxide interlayer is formed which contains three suboxide components (Zr+1, Zr+2 and Zr+3) and is located between the Zr surface and a stoichiometric ZrO2 overlayer that grows in a second, slow oxidation stage. The sole suboxide layer has been observed for the first time at very early states of the oxidation (oxygen exposure ≤4 L). The Ne+ FIM observations are in accord with a two stage process of Zr oxide formation. PMID:25766998

  9. A poly-epoxy surface explored by Hartree-Fock ΔSCF simulations of C1s XPS spectra.

    PubMed

    Gavrielides, A; Duguet, T; Esvan, J; Lacaze-Dufaure, C; Bagus, P S

    2016-08-21

    Whereas poly-epoxy polymers represent a class of materials with a wide range of applications, the structural disorder makes them difficult to model. In the present work, we use good experimental model samples in the sense that they are pure, fully polymerized, flat and smooth, defect-free, and suitable for ultrahigh vacuum x-ray photoelectron spectroscopy, XPS, experiments. In parallel, we perform Hartree-Fock, HF, calculations of the binding energies, BEs, of the C1s electrons in a model molecule composed of the two constituents of the poly-epoxy sample. These C1s BEs were determined using the HF ΔSCF method, which is known to yield accurate values, especially for the shifts of the BEs, ΔBEs. We demonstrate the benefits of combining rigorous theory with careful XPS measurements in order to obtain correct assignments of the C1s XPS spectra of the polymer sample. Both the relative binding energies-by the ΔSCF method-and relative intensities-in the sudden approximation, SA, are calculated. It results in an excellent match with the experimental spectra. We are able to identify 9 different chemical environments under the C1s peak, where an exclusively experimental work would have found only 3 contributions. In addition, we observe that some contributions are localized at discrete binding energies, whereas others allow a much wider range because of the variation of their second neighbor bound polarization. Therefore, HF-ΔSCF simulations significantly increase the spectral resolution of XPS and thus offer a new avenue for the exploration of the surface of polymers. PMID:27544119

  10. X-PEEM, XPS and ToF-SIMS characterisation of xanthate induced chalcopyrite flotation: Effect of pulp potential

    NASA Astrophysics Data System (ADS)

    Kalegowda, Yogesh; Chan, Yuet-Loy; Wei, Der-Hsin; Harmer, Sarah L.

    2015-05-01

    Synchrotron-based X-ray photoemission electron microscopy (X-PEEM), X-ray photo-electron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and ultraviolet visible spectroscopy were used to characterize the flotation behaviour of chalcopyrite with xanthate at different processing conditions. The flotation recovery of chalcopyrite decreased from 97% under oxidative conditions (Eh ~ 385 mV SHE, pH 4) to 41% at a reductive potential of - 100 mV SHE (at pH 9). X-PEEM images constructed from the metal L3 absorption edges were used to produce near-edge X-ray absorption fine structure (NEXAFS) spectra from regions of interest, allowing the variability in mineral surface chemistry of each mineral particle to be analysed, and the effect of pulp potential (Eh) on the flotation of chalcopyrite to be determined. XPS, ToF-SIMS and NEXAFS analyses of chalcopyrite particles at oxidative conditions show that the surface was mildly oxidised and covered with adsorbed molecular CuEX. The Cu 2p XPS and Cu L2,3 NEXAFS spectra were dominated by CuI species attributed to bulk chalcopyrite and adsorbed CuEX. At a reductive potential of - 100 mV SHE, an increase in concentration of CuI and FeIII oxides and hydroxides was observed. X-PEEM analysis was able to show the presence of a low percentage of CuII oxides (CuO or Cu(OH)2) with predominantly CuI oxide (Cu2O) which is not evident in Cu 2p XPS spectra.

  11. In situ XPS and MS study of methanol decomposition and oxidation on Pd(111) under millibar pressure range

    NASA Astrophysics Data System (ADS)

    Kaichev, V. V.; Miller, A. V.; Prosvirin, I. P.; Bukhtiyarov, V. I.

    2012-02-01

    The methanol decomposition and oxidation on a Pd(111) single crystal have been investigated in situ using ambient-pressure X-ray photoelectron spectroscopy (XPS) and mass-spectrometry (MS) in the temperature range of 300-600 K. It was found that even in the oxygen presence the methanol decomposition on palladium proceeds through two competitive routes: fast dehydrogenation to CO and H2, and slow decomposition of methanol via the C-O bond scission. The rate of the second route is significant even in the millibar pressure range, which leads to a blocking of the palladium surface by carbon and to a prevention of the further methanol conversion. As a result, no gas phase products of methanol decomposition were detected by mass-spectrometry at 0.1 mbar CH3OH in the whole temperature range. The methanol C-O bond scission produces CHx species, which fast dehydrogenate to atomic carbon even at room temperature and further partially dissolve in the palladium bulk at 400 K with the formation of the PdCx phase. According to in situ XPS data, the PdCx phase forms even in the oxygen excess. The application of an in situ XPS-MS technique unambiguously shows a good correlation between a decrease in the surface concentration of all carbon-containing species and the rate of methanol conversion. Since these carbon species have a high reactivity towards oxygen, heating of Pd(111) above 450 K in a methanol-oxygen mixture yields CO, CO2, and water. The product distribution indicates that the main route of methanol conversion is the dehydrogenation of methanol to CO and hydrogen. However, under the experimental conditions used, hydrogen is completely oxidized to water, while CO is partially oxidized to CO2. No palladium oxide was detected by XPS in these conditions.

  12. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    NASA Astrophysics Data System (ADS)

    Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

    2003-01-01

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment.

  13. Comparative study of the native oxide on 316L stainless steel by XPS and ToF-SIMS

    SciTech Connect

    Tardio, Sabrina Abel, Marie-Laure; Castle, James E.; Watts, John F.; Carr, Robert H.

    2015-09-15

    The very thin native oxide film on stainless steel, of the order of 2 nm, is known to be readily modified by immersion in aqueous media. In this paper, X-ray photoelectron spectroscopy (XPS) and time of flight secondary ions mass spectrometry are employed to investigate the nature of the air-formed film and modification after water emersion. The film is described in terms of oxide, hydroxide, and water content. The preferential dissolution of iron is shown to occur on immersion. It is shown that a water absorbed layer and a hydroxide layer are present above the oxide-like passive film. The concentrations of water and hydroxide appear to be higher in the case of exposure to water. A secure method for the peak fitting of Fe2p and Cr2p XPS spectra of such films on their metallic substrates is described. The importance of XPS survey spectra is underlined and the feasibility of C{sub 60}{sup +} SIMS depth profiling of a thin oxide layer is shown.

  14. XPS and ToF-SIMS Investigation of α-Helical and β-Strand Peptide Adsorption onto SAMs

    PubMed Central

    Apte, Julia S.; Collier, Galen; Latour, Robert A.; Gamble, Lara J.; Castner, David G.

    2009-01-01

    14-mer α-helix and a 15-mer β-strand oligopeptides composed of leucine (L) and lysine (K) were used to investigate peptide adsorption and orientation onto well-defined methyl and carboxylic acid terminated self-assembled monolayer (SAM) surfaces with X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). XPS showed both peptides reached monolayer thickness on both SAMs, but significantly higher solution concentrations were required to reach this coverage on the methyl SAMs. This shows that the peptides adsorb more strongly onto the carboxyl-terminated SAMs. The excess oxygen detected by XPS and the H3O+ signal detected by ToF-SIMS for the SAMs with adsorbed peptides indicated that water molecules are associated with the adsorbed peptides, even under ultra-high vacuum conditions. Changes in the amount of L and K fragments detected by ToF-SIMS indicate the β-strand oriented differently on the two SAMs. The L side-chains were preferentially associated with the methyl-terminated SAM and the K side-chains were preferentially associated with the carboxyl SAM. In contrast, little change in the ToF-SIMS K/L ratio was observed for the α-helix peptide absorbed on the two SAMs, indicating ToF-SIMS was not as sensitive to orientation of the α-helix peptide. PMID:19891457

  15. Chemical characterization of soot particles emitted by Wood-Burning Cook Stoves: A XPS and HRTEM study

    NASA Astrophysics Data System (ADS)

    Carabali, Giovanni; Peralta, Oscar; Castro, Telma; Torres, Ricardo; Ruiz, Gerardo; Molina, Luisa; Saavedra, Isabel

    2014-05-01

    The morphology, microstructure, chemical composition, and electronic structure of soot particles emitted directly from biofuel cook stoves have been studied by high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). In order to obtain freshly emitted soot particles, copper grids for Transmission Electron Microscope (TEM) were placed on the last two of an 8-stages MOUDI cascade impactor. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot chain. Additionally, the morphology of soot particles was analyzed calculating the border-based fractal dimension (Df). Particles sampled on the first heating stage exhibit complex shapes with high values of Df, which are present as aggregates formed by carbon ceno-spheres. The XPS survey spectrum for soot particles shows that the main particle composition is carbon. We also observed differences in the carbon/oxygen (C/O) ratio of the particles, which probably depends on the combustion process efficiency of each cook-stove analyzed. The XPS C-1s spectra show carbon with two peaks that correspond to sp2 and sp3 hybridization. Also, real-time absorption (βa) and scattering (αs) coefficients of the particles emitted by cook stoves were measured. The trend in βa and αs indicate that the cooking process has two important combustion stages which varied in its flaming strength, being vigorous in the first stage and soft in the second one.

  16. Effects of the low Earth orbit space environment on the surface chemistry of Kapton polyimide film: An XPS study

    NASA Technical Reports Server (NTRS)

    Lee, Myung; Rooney, William; Whiteside, James

    1992-01-01

    Kapton H (DuPont Trademark) polyimide specimens exposed to the low earth (LEO) space environment suffered significant weathering with surface erosions of approximately 8.0 microns. Despite these effects, no significant changes in bulk chemistry were observed. X-ray photoelectron spectroscopy (XPS) was used to determine local changes induced from approximately 25 percent in 1980 vintage ground control specimens to nearly 53 percent in space exposed specimens. The greatest increase was observed for the divalent oxygen moieties, although a slight increase in carbonyl oxygen was also measured. Furthermore, the chemical shifts of all XPS peaks of space-exposed Kapton are shifted to higher energy. This is consistent with a higher oxidation state of the space exposed surface. Finally, space exposed specimens had distinct silicon peaks (2p 100 eV and 2s 149 eV) in their XPS spectra in agreement with widespread reports of silicon contamination throughout the LDEF satellite. These results are discussed in terms of surface reactivity of the polyimide exposed to the LEO environment and the chemical nature of contaminants deposited on flight surfaces due to satellite outgassing.

  17. An XPS and SEM evaluation of six chemical and physical techniques for cleaning of contaminated titanium implants.

    PubMed

    Mouhyi, J; Sennerby, L; Pireaux, J J; Dourov, N; Nammour, S; Van Reck, J

    1998-06-01

    The purpose of the present study was to analyse clinically failed and retrieved implants prior to and after cleaning by means of scanning electron microscopy (SEM) and X-ray induced photoelectron spectroscopy (XPS) as compared to unused controls. Six different chemical and physical techniques for cleaning of contaminated titanium implants were evaluated: 1) rinsing in absolute ethanol for 10 min, 2) cleaning in ultrasonic baths containing trichloroethylene (TRI) and absolute ethanol, 10 min in each solution, 3) abrasive cleaning for 30 s, 4) cleaning in supersaturated citric acid for 30 s, 5) cleaning with continuous CO2-laser in dry conditions at 5 W for 10 s, 6) cleaning with continuous CO2-laser in wet conditions (saline) at 5 W for 10 s. SEM of failed implants showed the presence of contaminants of varying sizes and XPS showed almost no titanium but high carbon signals. XPS of unused titanium implants showed lower levels of titanium as previously reported, probably due to contamination of carbon which increased with time in room air. Cleaning of used implants in citric acid followed by rinsing with deionized water for 5 min followed by cleaning in ultrasonic baths with TRI and absolute ethanol gave the best results with regard to macroscopical appearance and surface composition. However, as compared to the unused implants the results from an element composition point of view were still unsatisfactory. It is concluded that further development and testing of techniques for cleaning of organically contaminated titanium is needed. PMID:10530133

  18. Internal translation initiation and eIF4F/ATP-independent scanning of mRNA by eukaryotic ribosomal particles

    PubMed Central

    Agalarov, Sultan Ch.; Sakharov, Pavel A.; Fattakhova, Dina Kh.; Sogorin, Evgeny A.; Spirin, Alexander S.

    2014-01-01

    The recombinant mRNAs with 5′-untranslated region, called omega leader, of tobacco mosaic virus RNA are known to be well translated in eukaryotic cell-free systems, even if deprived of cap structure. Using the method of primer extension inhibition (toe-printing), the ribosomal particles were shown to initiate translation at uncapped omega leader when its 5′-end was blocked by a stable RNA-DNA double helix, thus providing evidence for internal initiation. The scanning of the leader sequence and the formation of ribosomal 48S initiation complexes at the initiation AUG codon occurred in the absence of ATP-dependent initiation factor eIF4F, as well as without ATP. The latter results implied the ability of ribosomal initiation complexes for ATP-independent, diffusional wandering (also called bi-directional movement) along the leader sequence during scanning. PMID:24657959

  19. An Experimental and Theoretical Study of the Variation of 4f Hybridization Across the La1-xCexIn3 Series

    SciTech Connect

    Gout, Delphine J; Gourdon, Olivier; Bauer, E. D.; Ronning, F.; Thompson, J. D.; Proffen, Th.

    2008-01-01

    Crystal structures of a series of La1−xCexIn3 (x = 0.02, 0.2, 0.5, or 0.8) intermetallic compounds have been investigated by both neutron and X-ray diffraction, and their physical properties have been characterized by magnetic susceptibility and specific heat measurements. Our results emphasize atypical atomic displacement parameters (ADP) for the In and the rare-earth sites. Depending on the x value, the In ADP presents either an ellipsoidal elongation (La-rich compounds) or a butterfly-like distortion (Ce-rich compounds). These deformations have been understood by theoretical techniques based on the band theory and are the result of hybridization between conduction electrons and 4f-electrons.

  20. Arangasite, Al2(PO4)(SO4)F · 7.5H2O, a new mineral from the Alyaskitovy deposit, Eastern Yakutia, Russia

    NASA Astrophysics Data System (ADS)

    Gamyanin, G. N.; Zayakina, N. V.; Galenchikova, L. T.

    2014-12-01

    A new hydrous aluminum sulfate-phosphate-fluoride arangasite, Al2(PO4)(SO4)F · 7.5H2O, has been found in cassiterite-silicate-sulfide ore at the Alyaskitovy deposit, Indigirka River basin, eastern Sakha (Yakutia) (64°39' N, 142°70' E). The new mineral was named after its type locality, Arangas Creek. It belongs to the secondary minerals of the oxidation zone and occurs in cavities within quartz-muscovite-tourmaline-sulfide veins and adjacent greisen. Arangasite is associated with other secondary minerals: phosphorscorodite, fluellite, gypsum, colquiriite, strengite, mansfieldite, and sinkankasite. Arangasite forms white compact segregations composed of fine-lamellar aggregates. This paper reports data on its chemical composition, optical, radiographic, thermal, and IR-spectroscopic characteristics.

  1. A Monte Carlo Sensitivity Analysis of CF2 and CF Radical Densities in a c-C4F8 Plasma

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Rauf, Shahid; Hash, D. B.; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    A Monte Carlo sensitivity analysis is used to build a plasma chemistry model for octacyclofluorobutane (c-C4F8) which is commonly used in dielectric etch. Experimental data are used both quantitatively and quantitatively to analyze the gas phase and gas surface reactions for neutral radical chemistry. The sensitivity data of the resulting model identifies a few critical gas phase and surface aided reactions that account for most of the uncertainty in the CF2 and CF radical densities. Electron impact dissociation of small radicals (CF2 and CF) and their surface recombination reactions are found to be the rate-limiting steps in the neutral radical chemistry. The relative rates for these electron impact dissociation and surface recombination reactions are also suggested. The resulting mechanism is able to explain the measurements of CF2 and CF densities available in the literature and also their hollow spatial density profiles.

  2. Determination of GaN solubility in supercritical ammonia with NH4F and NH4Cl mineralizer by in situ x-ray imaging of crystal dissolution

    NASA Astrophysics Data System (ADS)

    Schimmel, Saskia; Lindner, Michael; Steigerwald, Thomas G.; Hertweck, Benjamin; Richter, Theresia M. M.; Künecke, Ulrike; Alt, Nicolas S. A.; Niewa, Rainer; Schlücker, Eberhard; Wellmann, Peter J.

    2015-05-01

    Quantitative data on the solubility of GaN in supercritical ammonia using NH4F as mineralizer are reported. The solubility is determined by in situ x-ray imaging of the dissolution of GaN single crystals. First, solubility values obtained by this method with NH4Cl as mineralizer are presented and discussed with respect to existing literature data. Monitoring the dissolution process in situ reveals the time when the solubility limit is reached. Thus, it allows to distinguish the saturation of the solution from dissolution based on mass transport and deposition. This is a key advantage of solubility measurements by in situ x-ray imaging compared to gravimetric methods. Our results indicate that the solubility limit is reached much faster than usually assumed in gravimetric solubility studies and the solubility of GaN in ammonothermal media is significantly lower than reported so far.

  3. High-speed anisotropic etching of quartz using SF 6/C 4F 8/Ar/O II based chemistry in inductively coupled plasma reactive ion etching system

    NASA Astrophysics Data System (ADS)

    Goyal, Abhijat; Hood, Vincent; Tadigadapa, Srinivas

    2006-01-01

    Etching of quartz and glass for microsystems applications requires optimization of the etch process for high etch rates, high aspect ratios and low rms surface roughness of the etched features. Typically, minimum surface roughness of the etched feature accompanied with maximum etch rate and anisotropy are desired. In this article, we investigate the effect of different gas chemistries on the etch rate and rms surface roughness of the Pyrex(R) 7740 in an inductively coupled plasma reactive ion etching (ICP-RIE) system. The gases considered were SF6 and c-C4F8, with additives gases comprising of O2, Ar, and CH4. A standard factorial design of experiment (DOE) methodology was used for finding the effect of variation of process parameters on the etch rate and rms surface roughness. By use of 2000 W of ICP power, 475 W of substrate power, SF6 flow rate of 5 sccm, Ar flow rate of 50 sccm, substrate holder temperature of 20°C, and distance of substrate holder from ICP source to be 120 mm, we were able to obtain an etch rate of 0.536 μm/min and a rms surface roughness of ~1.97 nm. For an etch process optimized for high etch rate and minimum surface roughness using C4F8/SF6/O2/Ar gases, an etch rate of 0.55 μm/min and a rms surface roughness of ~25 nm was obtained for SF6 flow rate of 5 sccm, C4F8 flow rate of 5 sccm, O2 flow rate of 50 sccm, Ar flow rate of 50 sccm. Keeping all other process parameters the same, increasing the SF6 flow rate to 50 sccm resulted in an etch rate of 0.7 μm/min at an rms surface roughness of ~800 nm whereas increasing the C4F8 flow rate to 50 sccm resulted in an etch rate of 0.67 μm/min at an rms surface roughness of ~450 nm . Addition of CH4 did not contribute significantly to the etch rate while at the same time causing significant increase in the rms surface roughness. Regression or least square fit was used define an arbitrary etch rate number (Wetch) and rms surface roughness number (Wrms). These numbers were calculated by least

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

    PubMed

    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. PMID:27243359

  5. Inhibition of VEGF-dependent angiogenesis by the anti-CD82 monoclonal antibody 4F9 through regulation of lipid raft microdomains.

    PubMed

    Nomura, Sayaka; Iwata, Satoshi; Hatano, Ryo; Komiya, Eriko; Dang, Nam H; Iwao, Noriaki; Ohnuma, Kei; Morimoto, Chikao

    2016-05-20

    CD82 (also known as KAI1) belongs to the tetraspanin superfamily of type III transmembrane proteins, and is involved in regulating cell adhesion, migration and proliferation. In contrast to these well-established roles of CD82 in tumor biology, its function in endothelial cell (EC) activity and tumor angiogenesis is yet to be determined. In this study, we show that suppression of CD82 negatively regulates vascular endothelial growth factor (VEGF)-induced angiogenesis. Moreover, we demonstrate that the anti-CD82 mAb 4F9 effectively inhibits phosphorylation of VEGF receptor 2 (VEGFR2), which is the principal mediator of the VEGF-induced angiogenic signaling process in tumor angiogenesis, by regulating the organization of the lipid raft microdomain signaling platform in human EC. Our present work therefore suggests that CD82 on EC is a potential target for anti-angiogenic therapy in VEGFR2-dependent tumor angiogenesis. PMID:27103437

  6. Synthesis of Thiazolo[5,4-f]quinazolin-9(8H)-ones as Multi-Target Directed Ligands of Ser/Thr Kinases.

    PubMed

    Hédou, Damien; Godeau, Julien; Loaëc, Nadège; Meijer, Laurent; Fruit, Corinne; Besson, Thierry

    2016-01-01

    A library of thirty novel thiazolo[5,4-f]quinazolin-9(8H)-one derivatives belonging to four series designated as 12, 13, 14 and 15 was efficiently prepared, helped by microwave-assisted technology when required. The efficient multistep synthesis of methyl 6-amino-2-cyano- benzo[d]thiazole-7-carboxylate (1) has been reinvestigated and performed on a multigram scale. The inhibitory potency of the final products against five kinases involved in Alzheimer's disease was evaluated. This study demonstrates that some molecules of the 12 and 13 series described in this paper are particularly promising for the development of new multi-target inhibitors of kinases. PMID:27144552

  7. Effects of sublattice positions and of asphericity of 4 f and 5 d charge densities on X-ray diffraction intensities in Tb and Dy

    NASA Astrophysics Data System (ADS)

    Eagles, D. M.

    1984-10-01

    Aspherical 5 d charge densities in a model for 5 d electrons in the heavy rare-earth metals developed by the present author produce small differences in X-ray diffraction intensities from those predicted by more traditional theories, in which anisotropy is significant only for 4 f shells. Diffraction intensities in Tb and Dy depend both on asphericities of charge densities and on the value of a parameter measuring the relative positions of sublattices in the low-temperature orthorhombically distorted structure of these metals. Predictions of ratios of intensities are made for several pairs of lines in each metal. Relative intensity measurements to an accuracy of the order of 1% should be sufficient to determine the sublattice displacements, but to distinguish between the model with large 5 d electric quadrupole and octupole moments and traditional theories would require accuracies of the order of 0.3%.

  8. Energy transfer and non-linear optical properties at near ultraviolet wavelengths: Rare earth 4f yields 5d transitions in crystals and glasses

    SciTech Connect

    Hamilton, D.S.

    1992-08-01

    The following topics were studied: two-photon transitions from 4f ground state to 5d excited states in Ce{sup 3+}:CaF{sub 2}; optical absorption and photoionization measurements from excited state of Ce{sup 3+}:Y{sub 3}Al{sub 5}O{sub 12}; excited state photoionization of Ce{sup 3+} ions in Ce{sub 3+}:CaF{sub 2}; optical gain and loss studies in Ce{sup 3+}:LiYF{sub 4}; Gd {yields}Cr energy transfer in Cr{sup 3+}:GSGG, Cr{sup 3+}:GSAG and Cr{sup 3+}:GGG crystals; nonradiative relaxation in Ce{sup 3+} doped crystals and glasses; and grating formation in impurity doped crystals.

  9. How I Do It: GreenLight XPS 180W photoselective vaporization of the prostate.

    PubMed

    Elterman, Dean S

    2015-06-01

    The treatments for benign prostate enlargement (BPE), also known as lower urinary tract symptoms secondary to benign prostatic hypertrophy (BPH-LUTS), have evolved significantly over recent years. Where transurethral resection of the prostate (TURP) has been the gold standard surgery for enlarged prostate glands < 80 grams, newer modalities such as laser technology have proliferated with safe and efficacious results. Notably, for prostates larger than 80-100 grams, the surgical options were an open, simple prostatectomy or perhaps a staged TURP. Both of these surgeries have the potential for bleeding complications, electrolyte abnormalities, and prolonged hospital admissions. Additional demographic and healthcare forces are also at play. Our aging population of men is being increasingly successfully treated for cardiovascular disease. This means more men are on anti-coagulation therapy, many of whom must stay on these drugs to prevent stent clotting or stroke. Hospital resources, especially overnight hospital admissions do add considerable strain to our healthcare systems. Men are also increasingly becoming more savvy consumers when it comes to their health. Many male patients would prefer to take as few medications as possible. Studies of BPH medications in Europe and the United States have shown drug discontinuation rates between 58%-70% at 1 year. Men who are faced with the choice of daily medication for life versus an outpatient procedure will often opt for the latter, which is in keeping with AUA guidelines that still put surgery as a patient choice alongside medications. Being able to offer GreenLight photoselective vaporization (GL-PVP) with the GreenLight XPS 180Watt system addresses all of these concerns. Men with bothersome BPH-LUTS with essentially any sized prostate gland, can be treated as same-day surgery requiring no overnight admission to hospital, while continuing necessary anti-coagulants, with significantly diminished risks of bleeding, erectile

  10. Investigation of fine atmospheric particle surfaces and lung lining fluid interactions using XPS

    NASA Astrophysics Data System (ADS)

    Kendall, Michaela; Hutton, Bernie M.; Tetley, Terry D.; Nieuwenhuijsen, Mark J.; Wigzell, Edward; Jones, Frances H.

    2001-07-01

    X-ray photoelectron spectroscopy (XPS) was used to determine surface chemical composition of atmospheric particles before and after immersion in saline and bronchoalveolar lavage fluid (BALF). Atmospheric particulate matter (PM 2.5) was collected on PTFE filters from clean air, outdoor urban and smoke-filled indoor sites. Low particle loads were present from the clean air site and the particle surface consisted of carbon, Cl - and oxide species. An increase in particle load was observed for the outdoor urban site with C(C, H) compounds dominating the particle surface. There was a significant contribution from C(O, N) and CO/COO-functionalities as well as oxides with traces of NO 3-, NH 4+, amide, SiC and SO 42- present. A further increase in particle load was observed for the smoke-filled indoor site. The surface consisted of 97% C(C, H) compounds with traces of oxide, amide and SiO 2. The particle load was reduced in all cases after immersion in saline mainly due to removal of loosely bound particles, especially for carbon. Changes in surface composition of the particles were also observed with removal of Cl - from the clean air site, NO 3-, NH 4+, amide, SO 42- and SiC from the urban air site and SiO 2 from the indoor smoke site; these species were deemed to be bio-available. Similar results were obtained after immersion in BALF. However, there was evidence of interaction of constituents from BALF with particles collected from the outdoor urban and indoor smoke sites. A strong amide signal was observed on particles remaining on the filter after immersion in BALF suggesting that possibly proteins or other N-containing biomolecular species from BALF were adsorbed on the surface of these particles. The surface concentrations of amide, oxide, C(O, N) and CO/COO - varied between outdoor urban and indoor smoke particles after immersion in BALF. This infers that a different interaction is occurring between BALF constituents and outdoor urban and indoor

  11. The roles of 4f- and 5f-orbitals in bonding: a magnetochemical, crystal field, density functional theory, and multi-reference wavefunction study.

    PubMed

    Lukens, W W; Speldrich, M; Yang, P; Duignan, T J; Autschbach, J; Kögerler, P

    2016-07-28

    The electronic structures of 4f(3)/5f(3) Cp''3M and Cp''3M·alkylisocyanide complexes, where Cp'' is 1,3-bis-(trimethylsilyl)cyclopentadienyl, are explored with a focus on the splitting of the f-orbitals, which provides information about the strengths of the metal-ligand interactions. While the f-orbital splitting in many lanthanide complexes has been reported in detail, experimental determination of the f-orbital splitting in actinide complexes remains rare in systems other than halide and oxide compounds, since the experimental approach, crystal field analysis, is generally significantly more difficult for actinide complexes than for lanthanide complexes. In this study, a set of analogous neodymium(iii) and uranium(iii) tris-cyclopentadienyl complexes and their isocyanide adducts was characterized by electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility. The crystal field model was parameterized by combined fitting of EPR and susceptibility data, yielding an accurate description of f-orbital splitting. The isocyanide derivatives were also studied using density functional theory, resulting in f-orbital splitting that is consistent with crystal field fitting, and by multi-reference wavefunction calculations that support the electronic structure analysis derived from the crystal-field calculations. The results highlight that the 5f-orbitals, but not the 4f-orbitals, are significantly involved in bonding to the isocyanide ligands. The main interaction between isocyanide ligand and the metal center is a σ-bond, with additional 5f to π* donation for the uranium complexes. While interaction with the isocyanide π*-orbitals lowers the energies of the 5fxz(2) and 5fyz(2)-orbitals, spin-orbit coupling greatly reduces the population of 5fxz(2) and 5fyz(2) in the ground state. PMID:27349178

  12. Syntheses, crystal structures and properties of series of 4d–4f ln(III)–Ag(I) heterometallic coordination polymers

    SciTech Connect

    Ran, Xing-Rui; Wang, Ning; Xie, Wei-Ping; Xiong, Yan-Ju; Cheng, Qian; Long, Yi; Yue, Shan-Tang; Liu, Ying-Liang

    2015-05-15

    By control of the experimental parameters such as ligands, pH value and reacting temperature, series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction, namely, ([Ln{sup III}Ag{sup I}(na)(ina)(ox)]·2(H{sub 2}O)){sub n} [Ln=Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Y(7), Yb(8)], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 2 and 4 and the magsnetic properties of complexes 3 and 5 were also investigated in detail. - Graphical abstract: Series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction which are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. - Highlights: • Complexes 1–8 are first built by three kinds of organic ligands based on nicotinic acid and isonicotinic acid. • PCPs 1–8 are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. • The total solvent-accessible volume of PCP 2 comprises 11.6% of the crystal volume after dislodging the free water molecules. • Complexes 2 and 4 exhibit characteristic lanthanide-centered luminescence, while compounds 3 and 5 show antiferromagnetic behaviors.

  13. Tombusvirus Y-Shaped Translational Enhancer Forms a Complex with eIF4F and Can Be Functionally Replaced by Heterologous Translational Enhancers

    PubMed Central

    Nicholson, Beth L.; Zaslaver, Olga; Mayberry, Laura K.; Browning, Karen S.

    2013-01-01

    Certain plus-strand RNA plant viruses that are uncapped and nonpolyadenylated rely on RNA elements in their 3′ untranslated region, termed 3′-cap-independent translational enhancers (3′CITEs), for efficient translation of their proteins. Here, we have investigated the properties of the Y-shaped class of 3′CITE present in the tombusvirus Carnation Italian ringspot virus (CIRV). While some types of 3′CITE have been found to function through recruitment of translation initiation factors to the viral genome, no trans-acting translation-related factors have yet been identified for the Y-shaped 3′CITE. Our results indicate that the CIRV 3′CITE complexes with eIF4F and eIFiso4F, with the former mediating translation more efficiently than the latter. In nature, some classes of 3′CITE are present in several different viral genera, suggesting that these elements hold a high degree of modularity. Here, we test this concept by engineering chimeric viruses containing heterologous 3′CITEs and show that the Y-shaped class of 3′CITE in CIRV can be replaced by two alternative types of 3′CITE, i.e., a Panicum mosaic virus-like 3′CITE or an I-shaped 3′CITE, without any major loss in in vitro translation or replication efficiency in protoplasts. The heterologous 3′CITEs also mediated whole-plant infections of Nicotiana benthamiana, where distinct symptoms were observed for each of the alternative 3′CITEs and 3′CITE evolution occurred during serial passaging. Our results supply new information on Y-shaped 3′CITE function and provide insights into 3′CITE virus-host compatibilities. PMID:23192876

  14. Core-core and core-valence correlation

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1988-01-01

    The effect of (1s) core correlation on properties and energy separations was analyzed using full configuration-interaction (FCI) calculations. The Be 1 S - 1 P, the C 3 P - 5 S and CH+ 1 Sigma + or - 1 Pi separations, and CH+ spectroscopic constants, dipole moment and 1 Sigma + - 1 Pi transition dipole moment were studied. The results of the FCI calculations are compared to those obtained using approximate methods. In addition, the generation of atomic natural orbital (ANO) basis sets, as a method for contracting a primitive basis set for both valence and core correlation, is discussed. When both core-core and core-valence correlation are included in the calculation, no suitable truncated CI approach consistently reproduces the FCI, and contraction of the basis set is very difficult. If the (nearly constant) core-core correlation is eliminated, and only the core-valence correlation is included, CASSCF/MRCI approached reproduce the FCI results and basis set contraction is significantly easier.

  15. Structure, stability, and photoluminescence in the anti-perovskites Na{sub 3}W{sub 1−x}Mo{sub x}O{sub 4}F (0≤x≤1)

    SciTech Connect

    Sullivan, Eirin; Avdeev, Maxim; Blom, Douglas A.; Gahrs, Casey J.; Green, Robert L.; Hamaker, Christopher G.; Vogt, Thomas

    2015-10-15

    Single-phase ordered oxyfluorides Na{sub 3}WO{sub 4}F, Na{sub 3}MoO{sub 4}F and their mixed members Na{sub 3}W{sub 1−x}Mo{sub x}O{sub 4}F can be prepared via facile solid state reaction of Na{sub 2}MO{sub 4}·2H{sub 2}O (M=W, Mo) and NaF. Phases produced from incongruent melts are metastable, but lower temperatures allow for a facile one-step synthesis. In polycrystalline samples of Na{sub 3}W{sub 1−x}Mo{sub x}O{sub 4}F, the presence of Mo stabilizes the structure against decomposition to spinel phases. Photoluminescence studies show that upon excitation with λ=254 nm and λ=365 nm, Na{sub 3}WO{sub 4}F and Na{sub 3}MoO{sub 4}F exhibit broad emission maxima centered around 485 nm. These materials constitute new members of the family of self-activating ordered oxyfluoride phosphors with anti-perovskite structures which are amenable to doping with emitters such as Eu{sup 3+}. - Graphical abstract: Directed synthesis of the ordered oxyfluorides Na{sub 3}W{sub 1−x}Mo{sub x}O{sub 4}F (0≤x≤1) has shown that a complete solid solution is attainable and provides the first example of photoluminescence in these materials. - Highlights: • Na{sub 3}W{sub 1−x}Mo{sub x}O{sub 4}F is a complete solid solution with hexagonal anti-perovskite structure. • The presence of even small amounts of Mo stabilizes the structure against decomposition. • Na{sub 3}W{sub 1−x}Mo{sub x}O{sub 4}F has broad emissions centered ≈485 nm (λ{sub ex}=254 nm and λ{sub ex}=365 nm). • These materials constitute a new family of self-activated oxyfluoride phosphors. • Na{sub 3}W{sub 1−x}Mo{sub x}O{sub 4}F materials are amenable to doping with emitters such as Eu{sup 3+}.

  16. Raman, EELS and XPS studies of maghemite decorated multi-walled carbon nanotubes.

    PubMed

    Zhang, Wei; Stolojan, Vlad; Silva, S Ravi P; Wu, Cheng Wei

    2014-01-01

    Iron oxide particles with the diameter being 5-10 nm were attached onto the sidewalls of multi-walled carbon nanotubes (MWCNTs) by the thermal decomposition of cyclopentadieny iron (II) dicarbonyl dimmer. The red shift of G-mode from 1579 cm(-1) to 1571 cm(-1) in the Raman profile of the decorated MWCNTs is indicative of the attachment of nanoparticles. Electron energy loss spectroscopy and X-ray photoelectron spectroscopy analyses reveals that the attached nanoparticles are composed of a maghemite phase. Transmission electron microscopy suggests the maghemite particles are covered with amorphous carbon materials and form a core-shell structure. PMID:24374884

  17. Ionic bonding of lanthanides, as influenced by d- and f-atomic orbitals, by core-shells and by relativity.

    PubMed

    Ji, Wen-Xin; Xu, Wei; Schwarz, W H Eugen; Wang, Shu-Guang

    2015-03-15

    Lanthanide trihalide molecules LnX3 (X = F, Cl, Br, I) were quantum chemically investigated, in particular detail for Ln = Lu (lutetium). We applied density functional theory (DFT) at the nonrelativistic and scalar and SO-coupled relativistic levels, and also the ab initio coupled cluster approach. The chemically active electron shells of the lanthanide atoms comprise the 5d and 6s (and 6p) valence atomic orbitals (AO) and also the filled inner 4f semivalence and outer 5p semicore shells. Four different frozen-core approximations for Lu were compared: the (1s(2) -4d(10) ) [Pd] medium core, the [Pd+5s(2) 5p(6) = Xe] and [Pd+4f(14) ] large cores, and the [Pd+4f(14) +5s(2) 5p(6) ] very large core. The errors of LuX bonding are more serious on freezing the 5p(6) shell than the 4f(14) shell, more serious upon core-freezing than on the effective-core-potential approximation. The LnX distances correlate linearly with the AO radii of the ionic outer shells, Ln(3+) -5p(6) and X(-) -np(6) , characteristic for dominantly ionic Ln(3+) -X(-) binding. The heavier halogen atoms also bind covalently with the Ln-5d shell. Scalar relativistic effects contract and destabilize the LuX bonds, spin orbit coupling hardly affects the geometries but the bond energies, owing to SO effects in the free atoms. The relativistic changes of bond energy BE, bond length Re , bond force k, and bond stretching frequency vs do not follow the simple rules of Badger and Gordy (Re ∼BE∼k∼vs ). The so-called degeneracy-driven covalence, meaning strong mixing of accidentally near-degenerate, nearly nonoverlapping AOs without BE contribution is critically discussed. PMID:25565146

  18. New Method for Determining the Elemental Composition and Distribution in Semiconductor Core-Shell Quantum Dots

    PubMed Central

    Zorn, Gilad; Dave, Shivang R.; Gao, Xiaohu; Castner, David G.

    2011-01-01

    In the biological sciences the use of core-shell quantum dots (QDs) has gained wide usage, but analytical challenges still exist for characterizing the QD structure. The application of energy-dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy (XPS) to bulk materials is relatively straightforward, however, for meaningful applications of surface science techniques to multilayer nanoparticles requires novel modifications and analysis methods. To experimentally characterize the elemental composition and distribution in CdSe/CdS/ZnS QDs, we first develop a XPS signal subtraction technique capable of separating the overlapped selenium 3s (core) and sulfur 2s (shell) peaks (both peaks have binding energies near 230eV) with higher precision than is typically reported in the nanoparticle literature. This method is valid for any nanoparticle containing selenium and sulfur. Then we apply a correction formula to the XPS data and determine that the 2 nm stoichiometric CdSe core is surrounded by 2 CdS layers and a stoichimetric ZnS monolayer. These findings and the multi-approach methodology represent a significant advancement in the detailed surface science study of multi-layer nanoparticles. In agreement with recent surprising findings, the time-of-flight secondary mass spectrometry measurements suggest that the surface sites of the QDs used in this study are primarily covered with a mixture of octadecylphosphonic acid and trioctylphophine oxide. PMID:21226467

  19. Investigating the complex mechanism of B migration in a magnetic-tunnel-junction trilayer structure—a combined study using XPS and TOF-SIMS

    NASA Astrophysics Data System (ADS)

    Ying, Ji-Feng; Ji, Rong; Ter Lim, Sze; Tran, Michael N.; Wang, Chen Chen; Ernult, Franck

    2016-02-01

    The magnetic-tunnel-junction (MTJ) structure is the core of many important devices, such as magnetic recording head and STT-RAM. CoFeB/MgO/CoFeB tri-layer thin-film stack is a widely researched MTJ structure. In this tri-layer, the functional property of the MTJ, i.e. its TMR ratio, is critically dependent on the crystal orientation of the CoFe grains. In order for the desired (1 0 0) out of plane texture to develop in the CoFeB layers, B needs to be engineered to be expelled out of these CoFeB layers, and diffuse or migrate into the adjacent layers. Ta is usually used as a seed layer adjacent to the MTJ structure. In this work, we investigated the important B-migration mechanisms within this MTJ structure through a combined XPS/TOF-SIMS study. Specifically, we tried to elucidate the possible physical/chemical interactions between the B and Ta that could happen with different film stack designs. Previous works have shown that there might be two possible B-migration mechanisms. One mechanism is direct B diffusion into the adjacent Ta layer during annealing. The other B-migration mechanism is through the formation of TaBOx species, in which B could be carried out by the Ta diffusion. In particular, through studying a series of film stacks, we discussed the circumstances under which one of these B-migration mechanisms becomes dominant. Furthermore, we discussed how these B-migration mechanisms facilitated the B expulsion in a common MTJ structure.

  20. Academic Rigor: The Core of the Core

    ERIC Educational Resources Information Center

    Brunner, Judy

    2013-01-01

    Some educators see the Common Core State Standards as reason for stress, most recognize the positive possibilities associated with them and are willing to make the professional commitment to implementing them so that academic rigor for all students will increase. But business leaders, parents, and the authors of the Common Core are not the only…

  1. Cation-Exchange Porosity Tuning in a Dynamic 4d-4f-3d Framework for Ni(II) Ion-Selective Luminescent Probe.

    PubMed

    Wang, Ying; Wang, Xiu-Guang; Yuan, Bin; Shao, Cheng-Yuan; Chen, Yuan-Yuan; Zhou, Bing-Bing; Li, Ming-Shu; An, Xiao-Mai; Cheng, Peng; Zhao, Xiao-Jun

    2015-05-01

    A heterometallic complex {[Yb2(L)6Cd2][Cd(H2O)6]·6H2O}n (Yb-Cd) (H2L = oxidiacetic acid) was synthesized under hydrothermal conditions. In Yb-Cd, each L chelates to one Yb(3+) center and bonds to two Cd(2+) ions in an anti-anti configuration. Yb and Cd atoms are arrayed alternatively and connected by O-C-O bridges to form a cubic octahedral cage as the secondary building unit. Consequently, topological NaCl nets with high symmetry in the cubic space group Fd-3c have been constructed. The [Cd(H2O)6](2+) moieties lying in the porosity of anionic metal-organic framework (MOF) act as the thermodynamically stable species, required to balance the two negative charges of [Yb2(L)6Cd2](2-) in Yb-Cd. Interestingly, when Yb-Cd was employed as a precursor and emerged in the aqueous solution of Mn(ClO4)2·6H2O or Zn(ClO4)2·6H2O, a reversible single-crystal-to-single-crystal transformation process driven by [Cd(H2O)6](2+) cations has been exhibited to generate the heterotrimetallic coordination polymer {[Yb2(L)6Cd2][Mn(H2O)6]·6H2O}n (Yb-Cd-Mn) or {[Yb2(L)6Cd2][Zn(H2O)6]·6H2O}n (Yb-Cd-Zn). To the best of out knowledge, Yb-Cd-Mn and Yb-Cd-Zn are the first examples representing 4d-4f-3d polymers based on multicarboxylic acid. Luminescent studies reveal that Yb-Cd-Zn may serve as a good candidate of Ni(2+) a luminescent probe. To our knowledge, Yb-Cd-Zn represent the fist example of the 4d-4f-3d framework to exhibit luminescent selectivity for Ni(2+). PMID:25885253

  2. Synthesis, crystal structures and luminescent properties of two 4d-4f Ln-Ag heterometallic coordination polymers based on anion template

    SciTech Connect

    Fan, Le-Qing; Chen, Yuan; Wu, Ji-Huai; Huang, Yun-Fang

    2011-04-15

    Two new 4d-4f Ln-Ag heterometallic coordination polymers, {l_brace}[Ln{sub 3}Ag{sub 5}(IN){sub 10}(H{sub 2}O){sub 7}].4(ClO{sub 4}).4(H{sub 2}O){r_brace}{sub n} (Ln=Eu (1) and Sm (2), HIN=isonicotinic acid), have been synthesized under hydrothermal conditions by reactions of Ln{sub 2}O{sub 3}, AgNO{sub 3}, HIN and HClO{sub 4}, and characterized by elemental analysis, IR, thermal analysis and single-crystal X-ray diffraction. It is proved that HClO{sub 4} not only adjusts the pH value of the reaction mixture, but also acts as anion template. The structure determination reveals that 1 and 2 are isostructural and feature a novel two-dimensional (2D) layered hetrometallic structure constructed from one-dimensional Ln-carboxylate chains and pillared Ag(IN){sub 2} units. The 2D layers are further interlinked through Ag...Ag and Ag...O(ClO{sub 4}{sup -}) multiple weak interactions, which form a rare Ag-ClO{sub 4} ribbon in lanthanide-transition metal coordination polymers, to give rise to a three-dimensional supramolecular architecture. Moreover, the luminescent properties of these two compounds have also been investigated at room temperature. -- Graphical abstract: Two new anion-templated 2D 4d-4f Ln-Ag heterometallic coordination polymers based on novel lanthanide-carboxylate chains and pillared Ag(IN){sub 2} units, {l_brace}[Ln{sub 3}Ag{sub 5}(IN){sub 10}(H{sub 2}O){sub 7}].4(ClO{sub 4}).4(H{sub 2}O){r_brace}{sub n} (Ln=Eu (1) and Sm (2), HIN=isonicotinic acid), have been hydrothermally synthesized and structurally characterized. 1 and 2 exhibit good luminescent properties. Display Omitted Research highlights: > Two 2D Eu (Sm)-Ag coordination polymers templated by perchlorate anion have been synthesized. > Polymers consist of novel 1D lanthanide-carboxylate chains. > In both structures, there are rare Ag...Ag and Ag...O(ClO{sub 4}{sup -}) multiple weak interactions. > Both compounds exhibit good luminescent properties.

  3. Conformations of polyaniline molecules adsorbed on Au(111) probed by in situ STM and ex situ XPS and NEXAFS.

    PubMed

    Lee, YiHui; Chang, ChinZen; Yau, ShuehLin; Fan, LiangJen; Yang, YawWen; Yang, LiangYueh Ou; Itaya, Kingo

    2009-05-13

    In situ scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure (NEXAFS) have been used to examine the conformation of a monolayer of polyaniline (PAN) molecules produced on a Au(111) single-crystal electrode by anodization at 1.0 V [vs reversible hydrogen electrode (RHE)] in 0.10 M H(2)SO(4) containing 0.030 M aniline. The as-produced PAN molecules took on a well-defined linear conformation stretching for 500 A or more, as shown by in situ and ex situ STM. The XPS and NEXAFS results indicated that the linear PAN seen at 1.0 V assumed the form of an emeraldine salt made of PAN chains and (bi)sulfate anions. Shifting the potential from 1.0 to 0.7 V altered the shape of the PAN molecules from straight to crooked, which was ascribed to restructuring of the Au(111) electrified interface on the basis of voltammetric and XPS results. In situ STM showed that further decreasing the potential to 0.5 V transformed the crooked PAN threads into a mostly linear form again, with preferential alignment and formation of some locally ordered structures. PAN molecules could be reduced from emeraldine to leucoemeraldine as the potential was decreased to 0.2 V or less. In situ STM showed that the fully reduced PAN molecules were straight but mysteriously shortened to approximately 50 A in length. The conformation of PAN did not recuperate when the potential was shifted positively to 1.0 V. PMID:19361217

  4. Solar Ion Processing of Major Element Surface Compositions of Mature Mare Soils: Insights from Combined XPS and Analytical TEM Observations

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Dukes, C.; Keller, L. P.; Baragiola, R.

    2012-01-01

    Solar wind ions are capable of altering the sur-face chemistry of the lunar regolith by a number of mechanisms including preferential sputtering, radiation-enhanced diffusion and sputter erosion of space weathered surfaces containing pre-existing compositional profiles. We have previously reported in-situ ion irradiation experiments supported by X-ray photoelectron spectroscopy (XPS) and analytical TEM that show how solar ions potentially drive Fe and Ti reduction at the monolayer scale as well as the 10-100 nm depth scale in lunar soils [1]. Here we report experimental data on the effect of ion irradiation on the major element surface composition in a mature mare soil.

  5. A XPS study of the Mo effect on passivation behaviors for highly controlled stainless steels in neutral and alkaline conditions

    NASA Astrophysics Data System (ADS)

    Mesquita, Thiago J.; Chauveau, Eric; Mantel, Marc; Nogueira, Ricardo P.

    2013-04-01

    The objective of this work is to study the effect of Mo additions on film passive properties of three different stainless steels (SS) types (austenitic, ferritic and duplex alloys). A comparison between Mo containing (3 wt% Mo) and free Mo (0 wt% Mo) grades of highly controlled laboratory heats was done considering their passive film formed in different aggressive conditions, from neutral to alkaline pH. The presence of oxidized Mo on the passive layer was confirmed by X-ray photoelectron Spectroscopy (XPS). The presence of Mo within the passive film improved the passivity breakdown potential for the duplex and ferritic SS, but seemed to have no effect for austenitic SS.

  6. An XPS study on the attachment of triethoxsilylbutyraldehyde to two titanium surfaces as a way to bond chitosan

    NASA Astrophysics Data System (ADS)

    Martin, Holly J.; Schulz, Kirk H.; Bumgardner, Joel D.; Walters, Keisha B.

    2008-05-01

    A bioactive coating has the ability to create a strong interface between bone tissue and implant. Chitosan, a biopolymer derived from the exoskeletons of shellfish, exhibits many bioactive properties that make it an ideal material for use as a coating such as antibacterial, biodegradable, non-toxic, and the ability to attract and promote bone cell growth and organized bone formation. A previous study reported on the bonding of chitosan to a titanium surface using a three-step process. In the current study, 86.4% de-acetylated chitosan coatings were bound to implant quality titanium in a two-step process that involved the deposition of triethoxsilylbutyraldehyde (TESBA) in toluene, followed by a reaction between the aldehyde of TESBA with chitosan. The chitosan coatings were examined on two different metal treatments to determine if any major differences in the ability of titanium to bind chitosan could be detected. The surface of the titanium metal and the individual reaction steps were examined using X-ray photoelectron spectroscopy (XPS). Following the deposition of TESBA, significant changes were seen in the amounts of oxygen, silicon, carbon, and titanium present on the titanium surface, which were consistent with the anticipated reaction steps. It was demonstrated that more TESBA was bound to the piranha-treated titanium surface as compared to the passivated titanium surface. The two different silane molecules, aminopropyltriethoxysilane (APTES) and TESBA, did not affect the chemistry of the resultant chitosan films. XPS showed that both the formation of unwanted polysiloxanes and the removal of the reactive terminal groups were prevented by using toluene as the carrier solvent to bond TESBA to the titanium surfaces, instead of an aqueous solvent. Qualitatively, the chitosan films demonstrated improved adhesion after using toluene, as the films remained attached to the titanium surface even when placed under the ultra-high vacuum necessary for XPS, unlike the

  7. DEAD-box protein DDX3 associates with eIF4F to promote translation of selected mRNAs.

    PubMed

    Soto-Rifo, Ricardo; Rubilar, Paulina S; Limousin, Taran; de Breyne, Sylvain; Décimo, Didier; Ohlmann, Théophile

    2012-09-12

    Here, we have characterized a step in translation initiation of viral and cellular mRNAs that contain RNA secondary structures immediately at the vicinity of their m(7)GTP cap. This is mediated by the DEAD-box helicase DDX3 which can directly bind to the 5' of the target mRNA where it clamps the entry of eIF4F through an eIF4G and Poly A-binding protein cytoplasmic 1 (PABP) double interaction. This could induce limited local strand separation of the secondary structure to allow 43S pre-initiation complex attachment to the 5' free extremity of the mRNA. We further demonstrate that the requirement for DDX3 is highly specific to some selected transcripts, cannot be replaced or substituted by eIF4A and is only needed in the very early steps of ribosome binding and prior to 43S ribosomal scanning. Altogether, these data define an unprecedented role for a DEAD-box RNA helicase in translation initiation. PMID:22872150

  8. 3d-4f spin interaction induced giant magnetocaloric effect in zircon-type DyCrO4 and HoCrO4 compounds

    NASA Astrophysics Data System (ADS)

    Midya, A.; Khan, N.; Bhoi, D.; Mandal, P.

    2013-08-01

    We have investigated the influence of 3d-4f spin interaction on magnetic and magnetocaloric properties of DyCrO4 and HoCrO4 compounds by magnetization and heat capacity measurements. Both the compounds exhibit complicated magnetic properties and huge magnetic entropy change around the ferromagnetic transition due to the strong competition between ferromagnetic and antiferromagnetic superexchange interactions. For a field change of 8 T, the maximum values of magnetic entropy change (ΔSMmax), adiabatic temperature change (ΔTad), and refrigerant capacity (RC) reach 29 J kg-1 K-1, 8 K, and 583 J kg-1, respectively, for DyCrO4 whereas the corresponding values for HoCrO4 are 31 J kg-1 K-1, 12 K, and 622 J kg-1. ΔSMmax, ΔTad, and RC are also quite large for a moderate field change. The large values of magnetocaloric parameters suggest that the zircon-type DyCrO4 and HoCrO4 could be the potential magnetic refrigerant materials for liquefaction of hydrogen.

  9. Molecular analysis of SMN1, SMN2, NAIP, GTF2H2, and H4F5 genes in 157 Chinese patients with spinal muscular atrophy.

    PubMed

    He, Jin; Zhang, Qi-Jie; Lin, Qi-Fang; Chen, Ya-Fang; Lin, Xiao-Zhen; Lin, Min-Ting; Murong, Shen-Xing; Wang, Ning; Chen, Wan-Jin

    2013-04-15

    Spinal muscular atrophy (SMA) is a common and lethal autosomal recessive neurodegenerative disorder, which is caused by mutations of the survival motor neuron 1 (SMN1) gene. Additionally, the phenotype is modified by several genes nearby SMN1 in the 5q13 region. In this study, we analyzed mutations in SMN1 and quantified the modifying genes, including SMN2, NAIP, GTF2H2, and H4F5 by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), multiplex ligation-dependent probe amplification (MLPA), TA cloning, allele-specific long-range PCR, and Sanger sequencing in 157 SMA patients. Most SMA patients (94.90%) possessed a homozygous SMN1 deletion, while 10 patients demonstrated only the absence of exon 7, but the presence of exon 8. Two missense mutations (c.689 C>T and c.844 C>T) were identified in 2 patients who both carried a single copy of SMN1. We found inverse correlations between SMN2, the NAIP copy number, and the clinical severity of the disease. Furthermore, 7 severe type I patients possessed large-scale deletions, including SMN1, NAIP, and GTF2H2. We conclude that SMN1 gene conversion, SMN1 subtle mutations, SMN2 copy number, and the extent of deletion in the 5q13 region should all be considered in the genotype-phenotype analysis of SMA. PMID:23352792

  10. Arachidonic Acid Pathway Members PLA2G7, HPGD, EPHX2, and CYP4F8 Identified as Putative Novel Therapeutic Targets in Prostate Cancer

    PubMed Central

    Vainio, Paula; Gupta, Santosh; Ketola, Kirsi; Mirtti, Tuomas; Mpindi, John-Patrick; Kohonen, Pekka; Fey, Vidal; Perälä, Merja; Smit, Frank; Verhaegh, Gerald; Schalken, Jack; Alanen, Kalle A.; Kallioniemi, Olli; Iljin, Kristiina

    2011-01-01

    The arachidonic acid and prostaglandin pathway has been implicated in prostate carcinogenesis, but comprehensive studies of the individual members in this key pathway are lacking. Here, we first conducted a systematic bioinformatic study of the expression of 36 arachidonic acid pathway genes across 9783 human tissue samples. The results showed that the PLA2G7, HPGD, EPHX2, and CYP4F8 genes are highly expressed in prostate cancer. Functional studies using RNA interference in prostate cancer cells indicated that all four genes are also essential for cell growth and survival. Clinical validation confirmed high PLA2G7 expression, especially in ERG oncogene-positive prostate cancers, and its silencing sensitized ERG-positive prostate cancer cells to oxidative stress. HPGD was highly expressed in androgen receptor (AR)-overexpressing advanced tumors, as well as in metastatic prostate cancers. EPHX2 mRNA correlated with AR in primary prostate cancers, and its inhibition in vitro reduced AR signaling and potentiated the effect of antiandrogen flutamide in cultured prostate cancer cells. In summary, we identified four novel putative therapeutic targets with biomarker potential for different subtypes of prostate cancer. In addition, our results indicate that inhibition of these enzymes may be particularly powerful when combined with other treatments, such as androgen deprivation or induction of oxidative stress. PMID:21281786

  11. Measurement of the radiative L3-M vacancy transfer probabilities of some 4f elements and compounds using Indus-2 synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Krishnananda; Mirji, Santosh; Badiger, N. M.; Tiwari, M. K.

    2016-08-01

    The L X-ray intensity ratios (ILα/ILl, ILα/ILβ, ILα/ILγ) and the radiative L3-M vacancy transfer probabilities (ηL3-M) of some 4f elements such as Gd, Tb, Ho and compounds; Pr2O3, Pr2(CO3)3·8H2O, Nd2O3, Sm2O3, Sm2(CO3)3·2.85H2O, Sm2(SO4)3·8H2O, Gd2(CO3)3, Tb2O3, Dy2(SO4)3, Ho2O3 and HoF3 have been measured using Indus-2 synchrotron radiation. The elements and compounds are excited by synchrotron radiation and the emitted characteristic L X-ray photons are measured with high resolution silicon drift detector. The measured intensity ratios of compounds are not influenced by the chemical environment. However, the ηL3-M values of compound targets indicate the effect of crystal structure.

  12. Hydrothermal synthesis of (C6N2H14)2(UVI2UIVO4F12), a mixed-valent one-dimensional uranium oxyfluoride.

    PubMed

    Allen, S; Barlow, S; Halasyamani, P S; Mosselmans, J F; O'Hare, D; Walker, S M; Walton, R I

    2000-08-21

    A new hybrid organic-inorganic mixed-valent uranium oxyfluoride, (C6N2H14)2(U3O4F12), UFO-17, has been synthesized under hydrothermal conditions using uranium dioxide as the uranium source, hydrofluoric acid as mineralizer, and 1,4-diazabicyclo[2.2.2]octane as template. The single-crystal X-ray structure was determined. Crystals of UFO-17 belonged to the orthorhombic space group Cmcm (no. 63), with a = 14.2660(15) A, b = 24.5130(10) A, c = 7.201(2) A, and Z = 4. The structure reveals parallel uranium-containing chains of two types: one type is composed of edge-sharing UO2F5 units; the other has a backbone of edge-sharing UF8 units, each sharing an edge with a pendant UO2F5 unit. Bond-valence calculations suggest the UF8 groups contain UIV, while the UO2F5 groups contain UVI. EXAFS data give results consistent with the single-crystal X-ray structure determination, while comparison of the uranium LIII-edge XANES of UFO-17 with that of related UIV and UVI compounds supports the oxidation-state assignment. Variable-temperature magnetic susceptibility measurements on UFO-17 and a range of related hybrid organic-inorganic uranium(IV) and uranium(VI) fluorides and oxyfluorides further support the formulation of UFO-17 as a mixed-valent UIV/UVI compound. PMID:11196771

  13. Potential Hazards Relating to Pyrolysis of c-C{sub 4}F{sub 8} in Selected Gaseous Diffusion Plant Operations

    SciTech Connect

    Trowbridge, L.D.

    1999-03-01

    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 in under way. One issue concerning a primary candidate, c-C4F8, is the possibility that it might produce the highly toxic perfluoroisobutylene (PFIB) in high temperature environments. This study was commissioned to determine the likelihood and severity of decomposition under two specific high temperature thermal environments, namely the use of a flame test for the presence of coolant vapors and welding in the presence of coolant vapors. The 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 formation of oxidation products (COF2, CO, CO2, and HF) rather than PFIB.

  14. Transcriptome profiling of induced hair cells (iHCs) generated by combined expression of Gfi1, Pou4f3 and Atoh1 during embryonic stem cell differentiation.

    PubMed

    Costa, Aida; Henrique, Domingos

    2015-12-01

    To gain new insights about the genetic networks controlling hair cell (HC) development, we previously developed a direct genetic programming strategy to generate an inexhaustible supply of HC-like cells (induced HCs, iHCs) in vitro, starting from mouse embryonic stem cells (ESC). We found that combined activity of three transcription factors, Gfi1, Pou4f3, and Atoh1, can program ESC-derived progenitors towards HC fate with efficiencies of 55%-80%. These iHCs express several HC markers and exhibit polarized structures that are highly reminiscent of the mechanosensitive hair bundles, with many microvilli-like stereocilia. Here, we describe the experimental design, methodology, and data validation for the microarray analysis used to characterize the transcriptome profile of iHCs at different stages of their differentiation. This approach based on FACS sorting and microarray analysis revealed a highly similar iHC transcriptome to that of endogenous HCs in vivo. The data obtained in this study is available in the Gene Expression Omnibus (GEO) database (accession number GSE60352). PMID:26697340

  15. XUV spectra of 2nd transition row elements: identification of 3d-4p and 3d-4f transition arrays

    NASA Astrophysics Data System (ADS)

    Lokasani, Ragava; Long, Elaine; Maguire, Oisin; Sheridan, Paul; Hayden, Patrick; O'Reilly, Fergal; Dunne, Padraig; Sokell, Emma; Endo, Akira; Limpouch, Jiri; O'Sullivan, Gerry

    2015-12-01

    The use of laser produced plasmas (LPPs) in extreme ultraviolet/soft x-ray lithography and metrology at 13.5 nm has been widely reported and recent research efforts have focused on developing next generation sources for lithography, surface morphology, patterning and microscopy at shorter wavelengths. In this paper, the spectra emitted from LPPs of the 2nd transition row elements from yttrium (Z = 39) to palladium (Z = 46), with the exception of zirconium (Z = 40) and technetium (Z = 43), produced by two Nd:YAG lasers which delivered up to 600 mJ in 7 ns and 230 mJ in 170 ps, respectively, are reported. Intense emission was observed in the 2-8 nm spectral region resulting from unresolved transition arrays (UTAs) due to 3d-4p, 3d-4f and 3p-3d transitions. These transitions in a number of ion stages of yttrium, niobium, ruthenium and rhodium were identified by comparison with results from Cowan code calculations and previous studies. The theoretical data were parameterized using the UTA formalism and the mean wavelength and widths were calculated and compared with experimental results.

  16. Structure and Thermal Expansion of Calcium-Thorium Apatite, [Ca4]F[Ca2Th4]T[(SiO4)6]O2.

    PubMed

    Bulanov, Evgeny N; Wang, Jingxian; Knyazev, Alexander V; White, Tim; Manyakina, Marina E; Baikie, Tom; Lapshin, Alexander N; Dong, ZhiLi

    2015-12-01

    Thorium silicate apatite with the formula [Ca3.84Th0.16]F[Ca2.79Th3.21]T(SiO4)6O2 · x(H) was synthesized by solid-state reaction, and its structure refined in P63/m from powder X-ray diffraction (XRD) data using the Rietveld method (a = 9.50172(9) Å, c = 6.98302(8) Å, V = 545.98(1) Å(3); R-Bragg = 2.102%). It was found that thorium partitions strongly to the tunnel (T) 6h position rather than the framework (F) 4f site. Fourier transform infrared spectroscopy revealed only SiO4 tetrahedron, with SiO5 and SiO6 groups, sometimes observed in siliceous apatites absent, at least to the limit of detection of this technique. Thermal expansion of the thorium apatite determined by high-temperature XRD from 298-1173 K found Δa (0.87%) dilation to exceed Δc (0.73%) with increasing temperature consistent with other silicate apatites. PMID:26562353

  17. Organized thiol functional groups in mesoporous core shell colloids

    SciTech Connect

    Marchena, Martin H.; Granada, Mara; Bordoni, Andrea V.; Joselevich, Maria; Troiani, Horacio; Williams, Federico J.; Wolosiuk, Alejandro

    2012-03-15

    The co-condensation in situ of tetraethoxysilane (TEOS) and mercaptopropyltrimethoxysilane (MPTMS) using cetyltrimethylammonium bromide (CTAB) as a template results in the synthesis of multilayered mesoporous structured SiO{sub 2} colloids with 'onion-like' chemical environments. Thiol groups were anchored to an inner selected SiO{sub 2} porous layer in a bilayered core shell particle producing different chemical regions inside the colloidal layered structure. X-Ray Photoelectron Spectroscopy (XPS) shows a preferential anchoring of the -SH groups in the double layer shell system, while porosimetry and simple chemical modifications confirm that pores are accessible. We can envision the synthesis of interesting colloidal objects with defined chemical environments with highly controlled properties. - Graphical abstract: Mesoporous core shell SiO{sub 2} colloids with organized thiol groups. Highlights: Black-Right-Pointing-Pointer Double shell mesoporous silica colloids templated with CTAB. Black-Right-Pointing-Pointer Sequential deposition of mesoporous SiO{sub 2} layers with different chemistries. Black-Right-Pointing-Pointer XPS shows the selective functionalization of mesoporous layers with thiol groups.

  18. Effects of gas flow rate on the etch characteristics of a low- k sicoh film with an amorphous carbon mask in dual-frequency CF4/C4F8/Ar capacitively-coupled plasmas

    NASA Astrophysics Data System (ADS)

    Kwon, Bong-Soo; Lee, Hea-Lim; Lee, Nae-Eung; Kim, Chang-Young; Choi, Chi Kyu

    2013-01-01

    Highly selective nanoscale etching of a low-dielectric constant (low- k) organosilicate (SiCOH) layer using a mask pattern of chemical-vapor-deposited (CVD) amorphous carbon layer (ACL) was carried out in CF4/C4F8/Ar dual-frequency superimposed capacitively-coupled plasmas. The etching characteristics of the SiCOH layers, such as the etch rate, etch selectivity, critical dimension (CD), and line edge roughness (LER) during the plasma etching, were investigated by varying the C4F8 flow rate. The C4F8 gas flow rate primarily was found to control the degree of polymerization and to cause variations in the selectivity, CD and LER of the patterned SiCOH layer. Process windows for ultra-high etch selectivity of the SiCOH layer to the CVD ACL are formed due to the disproportionate degrees of polymerization on the SiCOH and the ACL surfaces.

  19. Novel phosphate halides BaMnIII[PO4]FCl and BaMnIII[PO4]F2: Effects of mixed halides on crystal structures and magnetic properties

    NASA Astrophysics Data System (ADS)

    Pei, Da-Ting; Sun, Wei; Huang, Ya-Xi; Sun, Zhi-Mei; Pan, Yuanming; Mi, Jin-Xiao

    2016-02-01

    Two new phosphate halides BaMnIII[PO4]FCl (1) and BaMnIII[PO4]F2 (2), have been synthesized under hydrothermal conditions. Structural characterizations show that both new compounds adopt layered structures but with different polyhedral linkages. Introduction of Cl into Compound (1) results in isolated hemimorphic [MnO4FCl] octahedra, different from the chain of [MnO4F2]/[MnO2F4] octahedra in Compound (2). These compounds have significantly different molecular vibration modes and thermal stabilities. Magnetic measurements reveal that Compound (2) has larger antiferromagnetic interactions than Compound (1), because the former has strong interactions between Mn3+-Mn3+ ions within corner-shared Mn3+-octahedral chains whereas the latter only possesses isolated Mn3+-octahedra. Both compounds transform to a new orthorhombic compound BaMnII(PO4)F (3) after thermal decomposition.

  20. Apolipoprotein A-I Mimetic Peptide D-4F Reduces Cardiac Hypertrophy and Improves Apolipoprotein A-I-Mediated Reverse Cholesterol Transport From Cardiac Tissue in LDL Receptor-null Mice Fed a Western Diet.

    PubMed

    Han, Jie; Zhang, Song; Ye, Ping; Liu, Yong-Xue; Qin, Yan-Wen; Miao, Dong-Mei

    2016-05-01

    Epidemiological studies have suggested that hypercholesterolemia is an independent determinant of increased left ventricular (LV) mass. Because high-density lipoprotein and its major protein apolipoprotein A-I (apoA-I) mediate reverse cholesterol transport (RCT) and have cardiac protective effects, we hypothesized that the apoA-I mimetic peptide D-4F could promote RCT in cardiac tissue and decrease cardiac hypertrophy induced by hypercholesterolemia. Low-density lipoprotein receptor-null mice were fed by a Western diet for 18 weeks and then randomized to receive water, or D-4F 0.3 mg/mL, or D-4F 0.5 mg/mL added to drinking water for 6 weeks. After D-4F administration, an increase in high-density lipoprotein cholesterol and a decrease in low-density lipoprotein cholesterol, total cholesterol, and triglyceride in a trend toward dose-responsivity were found in cardiac tissue. Ultrasound biomicroscopy revealed a reduction in LV posterior wall end-diastolic dimension, and an increase in mitral valve E/A ratio and LV ejection fraction. Hematoxylin-eosin staining showed reduced LV wall thickness and myocardial cell diameter. The protein levels of ABCA1 and LXRα were elevated in cardiac tissue of D-4F treated mice compared with the controls (P < 0.05). These results demonstrated that D-4F treatment reduced cardiac hypertrophy, and improved cardiac performance in low-density lipoprotein receptor-null mice fed a Western diet, presumably through the LXRα-ABCA1 pathway associated with enhanced myocardial RCT. PMID:26828321