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Sample records for 4f xps core

  1. 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.

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

    PubMed

    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. XPS studies of the valence band and of the 4f and 3d levels of Ce hydrides

    NASA Astrophysics Data System (ADS)

    Schlapbach, L.; Osterwalder, J.

    1982-04-01

    We have analyzed the valence band region and the 3d core levels of Ce, CeH 2.1 and CeH 2.9 by means of X-ray photoelectron spectroscopy. Hydrogen induced states appear about 5 eV below E F. The density of states at E F is about 4 times smaller in CeH 2.1 than in Ce and vanishes completely in CeH 2.9 in agreement with the metal to semiconductor transition which was observed in resistivity measurements. The 4f level is well split off the hydrogen induced band at 2 eV for both hydrides. The 3d core levels are shifted by 1.9 and 2.1 eV from Ce to CeH 2.1 and CeH 2.9, resp., and exhibit intense satellites on the low BE side. A simple method to prepare large, compact samples of rare earth hydrides is described.

  4. XPS-and-DFT analyses of the Pb 4f - Zn 3s and Pb 5d - O 2s overlapped ambiguity contributions to the final electronic structure of bulk and thin-film Pb-modulated zincite

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Gavrilov, N. V.; Kurmaev, E. Z.; Zatsepin, A. F.; Cui, L.; Shur, V. Ya.; Esin, A. A.

    2017-05-01

    The electronic structures of zincite Pb-modulated bulk and thin-films were studied via X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) techniques. Both XPS data and DFT-calculations allowed the derivation of two different Pb-embedding scenarios into the ZnO-hosts. These included the high-interaction mode of Pb-impurity with initial zinc-oxygen host-lattice for the bulk morphology, accompanied with low Pb-metal losses; and the low-interaction mode for thin-films, where there was intake of Pb-impurities into the hollows of the surface. Despite dissimilar mechanisms of Pb-impurity accumulation and distribution in the bulk and thin-films zincite host-matrices, the strong Pb 4f - Zn 3s and Pb 5d - O 2s overlapped ambiguity contribution to the appropriate core-level structure and valence bands was established by XPS analysis and reproduced with the help of DFT-calculations. It was shown that the microscopic structure of the embedded lead-impurity played a crucial role in the Pb ion-beam stimulated synthesis of secondary lead-oxygen phases via large-area defect fabrication, and the difference among zincite and wurzite polymorphs played almost no role in this case.

  5. 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

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Yamauchi, Jun; Yoshimoto, Yoshihide; Suwa, Yuji

    2013-12-01

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

  9. A Technique for Calculation of Shell Thicknesses for Core-Shell-Shell Nanoparticles from XPS Data

    PubMed Central

    Cant, David J. H.; Wang, Yung-Chen; Castner, David G.; Shard, Alexander G.

    2016-01-01

    This paper extends a straightforward technique for the calculation of shell thicknesses in core-shell nanoparticles to the case of core-shell-shell nanoparticles using X-ray Photoelectron Spectroscopy (XPS) data. This method can be applied by XPS analysts and does not require any numerical simulation or advanced knowledge, although iteration is required in the case where both shell thicknesses are unknown. The standard deviation in the calculated thicknesses vs simulated values is typically less than 10%, which is the uncertainty of the electron attenuation lengths used in XPS analysis. PMID:27087712

  10. Gold/silver core-shell 20 nm nanoparticles extracted from citrate solution examined by XPS

    SciTech Connect

    Engelhard, Mark H.; Smith, Jordan N.; Baer, Donald R.

    2016-06-01

    Silver nanoparticles of many types are widely used in consumer and medical products. The surface chemistry of particles and the coatings that form during synthesis or use in many types of media can significantly impact the behaviors of particles including dissolution, transformation and biological or environmental impact. Consequently it is useful to be able to extract information about the thickness of surface coatings and other attributes of nanoparticles produced in a variety of ways. It has been demonstrated that X-ray Photoelectron Spectroscopy (XPS) can be reliably used to determine the thickness of organic and other nanoparticles coatings and shells. However, care is required to produce reliable and consistent information. Here we report the XPS spectra from gold/silver core-shell nanoparticles of nominal size 20 nm removed from a citrate saturated solution after one and two washing cycles. The Simulation of Electron Spectra for Surface Analysis (SESSA) program had been used to model peak amplitudes to obtain information on citrate coatings that remain after washing and demonstrate the presence of the gold core. This data is provided so that others can compare use of SESSA or other modeling approaches to quantify the nature of coatings to those already published and to explore the impacts particle non-uniformities on XPS signals from core-shell nanoparticles.

  11. New type of heterometallic 3d-4f rhomblike core in Weakley-like polyoxometalates.

    PubMed

    Reinoso, Santiago; Galán-Mascarós, José Ramón; Lezama, Luis

    2011-10-03

    The first heterometallic copper-cerium polyoxometalate, [{Ce(IV)(OAc)}Cu(II)(3)(H(2)O)(B-α-GeW(9)O(34))(2)](11-) (1), is composed of an unprecedented copper(II)-trisubstituted Weakley-type tungstogermanate subunit stabilized by coordination of a {Ce(OAc)}(3+) group at the vacant position. The title species contains a central {Ce(IV)Cu(II)(3)O(18)} rhomblike cluster that belongs to a new {(4f(ext))(3d(ext))(3d(int))(2)} type and magnetically behaves as a triangular Cu(3) system with overall antiferromagnetic exchange affected by the structural distortions the vicinity of diamagnetic Ce(IV) induces.

  12. Quantifying the Impact of Nanoparticle Coatings and Nonuniformities on XPS Analysis: Gold/Silver Core-Shell Nanoparticles.

    PubMed

    Wang, Yung-Chen; Engelhard, Mark H; Baer, Donald R; Castner, David G

    2016-04-05

    Spectral modeling of photoelectrons can serve as a valuable tool when combined with X-ray photoelectron spectroscopy (XPS) analysis. Herein, a new version of the NIST Simulation of Electron Spectra for Surface Analysis (SESSA 2.0) software, capable of directly simulating spherical multilayer NPs, was applied to model citrate stabilized Au/Ag-core/shell nanoparticles (NPs). The NPs were characterized using XPS and scanning transmission electron microscopy (STEM) to determine the composition and morphology of the NPs. The Au/Ag-core/shell NPs were observed to be polydispersed in size, nonspherical, and contain off-centered Au-cores. Using the average NP dimensions determined from STEM analysis, SESSA spectral modeling indicated that washed Au/Ag-core-shell NPs were stabilized with a 0.8 nm layer of sodium citrate and a 0.05 nm (one wash) or 0.025 nm (two wash) layer of adventitious hydrocarbon, but did not fully account for the observed XPS signal from the Au-core. This was addressed by a series of simulations and normalizations to account for contributions of NP nonsphericity and off-centered Au-cores. Both of these nonuniformities reduce the effective Ag-shell thickness, which effect the Au-core photoelectron intensity. The off-centered cores had the greatest impact for the particles in this study. When the contributions from the geometrical nonuniformities are included in the simulations, the SESSA generated elemental compositions that matched the XPS elemental compositions. This work demonstrates how spectral modeling software such as SESSA, when combined with experimental XPS and STEM measurements, advances the ability to quantitatively assess overlayer thicknesses for multilayer core-shell NPs and deal with complex, nonideal geometrical properties.

  13. Quantifying the Impact of Nanoparticle Coatings and Non-uniformities on XPS Analysis: Gold/silver Core-shell Nanoparticles

    SciTech Connect

    Wang, Yung-Chen Andrew; Engelhard, Mark H.; Baer, Donald R.; Castner, David G.

    2016-03-07

    Abstract or short description: Spectral modeling of photoelectrons can serve as a valuable tool when combined with X-ray photoelectron spectroscopy (XPS) analysis. Herein, a new version of the NIST Simulation of Electron Spectra for Surface Analysis (SESSA 2.0) software, capable of directly simulating spherical multilayer NPs, was applied to model citrate stabilized Au/Ag-core/shell nanoparticles (NPs). The NPs were characterized using XPS and scanning transmission electron microscopy (STEM) to determine the composition and morphology of the NPs. The Au/Ag-core/shell NPs were observed to be polydispersed in size, non-circular, and contain off-centered Au-cores. Using the average NP dimensions determined from STEM analysis, SESSA spectral modeling indicated that washed Au/Ag-core shell NPs were stabilized with a 0.8 nm l

  14. The first 4d/4f single-molecule magnet containing a {Ru(III)2Dy(III)2} core.

    PubMed

    Langley, Stuart K; Wielechowski, Daniel P; Vieru, Veacheslav; Chilton, Nicholas F; Moubaraki, Boujemaa; Chibotaru, Liviu F; Murray, Keith S

    2015-02-07

    We report the synthesis, structure and magnetic properties of the first 4d-4f single-molecule magnet. The complex [Ru(III)2Dy(III)2(OMe)2(O2CPh)4(mdea)2(NO3)2] displays a butterfly type core, with an anisotropy barrier of 10.7 cm(-1). Ab initio and DFT calculations provide insight into the observed magnetic behaviour.

  15. Recent advances in the practical and accurate calculation of core and valence XPS spectra of polymers: From interpretation to simulation?

    NASA Astrophysics Data System (ADS)

    Bureau, Christophe; Chong, Delano P.; Endo, Kazunaka; Delhalle, Joseph; Lecayon, Gérard; Le Moël, Alain

    1997-08-01

    Core and valence X-ray Photoelectron Spectroscopies (XPS) are routinely used to obtain information on the chemical composition, bonding and homogeneity of polymer surfaces. In spite of their apparent conceptual simplicity, Core and Valence Electron Binding Energies (CEBEs and VEBEs) a few electron-volts (eV) or fractions of an eV apart are difficult to interpret. We present some results obtained with various recent theoretical approaches. An emphasis is made on a procedure based on the Density Functional Theory (DFT) that enables the calculation of CEBEs and VEBEs which are in remarkable agreement with experiment. The method has been tested on numerous small (3-6 atoms) to fairly large (15-25 atoms) molecules, and shows an average absolute deviation with experiment of only 0.20 eV for CEBEs and 0.30 eV for VEBEs, i.e. compatible with the resolution of the best XPS experiments carried out at the moment. Besides the quality of its predictions, the procedure takes advantage of the speed and CPU time scaling of DFT as a function of system size: it is computationally tractable, even for surprisingly large systems such as polymers, and may be an interesting accurate alternative to interpret and simulate XPS-probing on real systems. We illustrate the usefullness and pitfalls of this approach in fundamental as well as applied fields such as in the study of Polyacrylonitrile (PAN), Polytetrafluoroethylene (PTFE), Polyvinyldifluoride (PVdF) and γ-Aminopropyltriethoxysilane (γ-APS, an adhesion promoter).

  16. 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.

  17. 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.

  18. XPS Determination of Uranium Oxidations States

    SciTech Connect

    Ilton, Eugene S.; Bagus, Paul S.

    2011-12-01

    This contribution is both a review of different aspects of the XPS spectra that can help one determine U oxidation states and a personal perspective on how to effectively model the XPS of complicated mixed valence U phases. After a discussion of the valence band, the focus lingers on the U4f region, where the use of binding energies, satellite structures, and peak shapes is discussed in some detail. Binding energies were shown to be very dependent on composition/structure and consequently unreliable guides to oxidation state, particularly where assignment of composition is difficult. Likewise, the spin orbit split 4f7/2 and 4f5/2 peak shapes do not carry significant information on oxidation states. In contrast, both satellite-primary peak binding energy separations, as well as intensities too lesser extent, are relatively insensitive to composition/structure within the oxide-hydroxide-hydrate system and can be used to both identify and help quantify U oxidation states in mixed valence phases. An example of the usefulness of the satellite structure in constraining the interpretation of a complex multivalence U compound is given.

  19. pH dependence of uranyl retention in a quartz/solution system: an XPS study.

    PubMed

    Froideval, A; Del Nero, M; Barillon, R; Hommet, J; Mignot, G

    2003-10-15

    We have investigated the pH dependence of U(VI) retention in quartz/10(-4) M uranyl solution systems, under conditions favoring formation of polynuclear aqueous species and of colloids of amorphous schoepite as U(VI) solubility-limiting phases. X-ray photoelectron spectroscopy was used to gain insights into the coordination environments of sorbed/precipitated uranyl ions in the centrifuged quartz samples. The U4f XPS spectra made it possible to identify unambiguously the presence of two uranyl components. A high binding energy component, whose relative proportion increases with pH, exhibits the U4f lines characteristic of a reference synthetic metaschoepite. Such a high binding energy component is interpreted as a component having a U(VI) oxide hydrate character, either as polynuclear surface oligomers and/or as amorphous schoepite-like (surface) precipitates. Its pH dependence suggests that a binding of polynuclear species at quartz surfaces and/or a formation of amorphous schoepite-like (surface) precipitates is favored when the proportion of aqueous polynuclear species increases. A second surface component exhibits binding energies for the U4f core levels at values significantly lower (DeltaE(b)=1.2 eV) than for metaschoepite, evidencing uranyl ions in a distinct coordination environment. Such a low binding energy component may be attributed to monomeric uranyl surface complexes on the basis of published EXAFS data. Such a hypothesis is supported by a major contribution of the low binding energy component to the U4f XPS spectra of reference samples for uranyl sorbed on quartz from very acidic 10(-3) M uranyl solutions where UO(2)(2+) ions predominate.

  20. Toward a comprehensive understanding of solid-state core-level XPS linewidths: Experimental and theoretical studies on the Si2p and O1s linewidths in silicates

    NASA Astrophysics Data System (ADS)

    Bancroft, G. M.; Nesbitt, H. W.; Ho, R.; Shaw, D. M.; Tse, J. S.; Biesinger, M. C.

    2009-08-01

    High resolution X-ray Photoelectron Spectroscopy (XPS) core-level Si2p and O1s spectra of the nonconductors α-SiO2 (quartz) at 120 and 300 K and vitreous SiO2 at 300 K were obtained with a Kratos Axis Ultra XPS instrument (instrumental resolution of <0.4eV ) which incorporates a unique charge compensation system that minimizes differential charge broadening on nonconductors. The Si2p and O1s linewidths at 300 K ( ˜1.1 and ˜1.2eV , respectively) are similar for all silicates (and similar to previous thin film SiO2 spectra obtained previously), showing that differential charging does not contribute significantly to our spectra. At 120 K, there is a small decrease (0.04 eV) in the Si2p linewidth of α-SiO2 , but no measurable decrease in O1s linewidth. The O1s lines are generally and distinctly asymmetric. We consider all possible sources of line broadening and show that final state vibrational broadening (FSVB) and phonon broadening are the major causes of the broad and asymmetric lines. Previous high resolution gas phase XPS studies have identified large FSVB contributions to the Si2p spectra of SiCl4 , SiF4 , and Si(OCH3)4 molecules, and this vibrational structure leads total Si2p3/2 linewidths of up to ˜0.5eV , even with individual peak linewidths of <0.1eV . The Si atom of Si(OCH3)4 is an excellent analog for Si in crystalline SiO2 because the Si-O bond lengths and symmetric stretch frequencies are similar in both compounds. Similar vibrational contributions to the Si2p and O1s spectra of solid silicates are anticipated if the Si2p and O1s core-hole states produce similar changes to the Si-O bond length in both phases. To investigate the possibility, Car-Parrinello molecular dynamics calculations were performed and show that changes to Si-O bond lengths between ion and ground states (Δr) for both Si2p and O1s hole states are similar for both crystalline SiO2 and gaseous Si(OCH3)4 . Δr are -0.04Å for Si2p and ˜+0.05Å for O1s in both compounds. Indeed, the

  1. eIF4F: A Retrospective*

    PubMed Central

    Merrick, William C.

    2015-01-01

    The original purification of the heterotrimeric eIF4F was published over 30 years ago (Grifo, J. A., Tahara, S. M., Morgan, M. A., Shatkin, A. J., and Merrick, W. C. (1983) J. Biol. Chem. 258, 5804–5810). Since that time, numerous studies have been performed with the three proteins specifically required for the translation initiation of natural mRNAs, eIF4A, eIF4B, and eIF4F. These have involved enzymatic and structural studies of the proteins and a number of site-directed mutagenesis studies. The regulation of translation exhibited through the mammalian target of rapamycin (mTOR) pathway is predominately seen as the phosphorylation of 4E-BP, an inhibitor of protein synthesis that functions by binding to the cap binding subunit of eIF4F (eIF4E). A hypothesis that requires the disassembly of eIF4F during translation initiation to yield free subunits (eIF4A, eIF4E, and eIF4G) is presented. PMID:26324716

  2. The problematic C2H4+F2 reaction barrier

    NASA Astrophysics Data System (ADS)

    Feng, Hao; Allen, Wesley D.

    2010-03-01

    The C2H4+F2 reaction is investigated through the most rigorous electronic structure methods currently feasible, using a focal point approach to converge toward the ab initio limit. Explicit computations were executed with basis sets as large as aug-cc-pV5Z and correlation treatments as extensive as coupled cluster through full triples with a perturbative inclusion of quadruple excitations [CCSDT(Q)]. Auxiliary core correlation, diagonal Born-Oppenheimer, and first-order relativistic corrections were included. All optimized geometries and vibrational frequencies were determined completely at the CCSD(T)/aug-cc-pVQZ level. The final C2H4+F2 reaction barrier from theory (8.0 kcal mol-1) is significantly higher than the recently reported experimental barrier (5.5±0.5 kcal mol-1). Our computations also yield a new enthalpy of formation of the fluoroethyl radical, ΔfH298°(C2H4F)=-13.2±0.2 kcal mol-1, whose uncertainty is an order of magnitude less than previous experimental values.

  3. 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.

  4. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... With Historic Sites; (4) Historic Bridges; Programmatic Section 4(f) Evaluation and Approval; and (5) Section 4(f) Statement and Determination for Independent Bikeway or Walkway Construction Projects. (1) The... Administration may develop additional programmatic Section 4(f) evaluations. Proposed new or revised programmatic...

  5. 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 public...

  6. 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}.

  7. 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.

  8. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., RECREATION AREAS, WILDLIFE AND WATERFOWL REFUGES, AND HISTORIC SITES (SECTION 4(F)) § 774.3 Section 4(f...) Causes the least overall harm in light of the statute's preservation purpose. The least overall harm is... With Public Parks, Recreation Lands, Wildlife and Waterfowl Refuges, and Historic Sites; (3) Final...

  9. Unusual Mixed Valence of Eu in Two Materials-EuSr2Bi2S4F4 and Eu2SrBi2S4F4: Mössbauer and X-ray Photoemission Spectroscopy Investigations.

    PubMed

    Haque, Zeba; Thakur, Gohil Singh; Parthasarathy, Rangasamy; Gerke, Birgit; Block, Theresa; Heletta, Lukas; Pöttgen, Rainer; Joshi, Amish G; Selvan, Ganesan Kalai; Arumugam, Sonachalam; Gupta, Laxmi Chand; Ganguli, Ashok Kumar

    2017-02-28

    We have synthesized two new Eu-based compounds, EuSr2Bi2S4F4 and Eu2SrBi2S4F4, which are derivatives of Eu3Bi2S4F4, an intrinsic superconductor with Tc = 1.5 K. They belong to a tetragonal structure (SG: I4/mmm, Z = 2), similar to the parent compound Eu3Bi2S4F4. Our structural and (151)Eu Mössbauer spectroscopy studies show that, in EuSr2Bi2S4F4, Eu-atoms exclusively occupy the crystallographic 2a-sites. In Eu2SrBi2S4F4, 2a-sites are fully occupied by Eu-atoms and the other half of Eu-atoms and Sr-atoms together fully occupy 4e-sites in a statistical distribution. In both compounds Eu atoms occupying the crystallographic 2a-sites are in a homogeneous mixed valent state ∼2.6-2.7. From our magnetization studies in an applied H ≤ 9 T, we infer that the valence of Eu-atoms in Eu2SrBi2S4F4 at the 2a-sites exhibits a shift toward 2+. Our XPS studies corroborate the occurrence of valence fluctuations of Eu and after Ar-ion sputtering show evidence of enhanced population of Eu(2+)-states. Resistivity measurements, down to 2 K, suggest a semimetallic nature for both compounds.

  10. XPS and SPR analysis of glycoarray surface density.

    PubMed

    Dhayal, Marshal; Ratner, Daniel M

    2009-02-17

    Despite the fact that the carbohydrate microarray has seen increasing use within the field of glycobiology, the surface chemistry of the glycoarray remains largely unexplored. Motivated by the need to develop surface analytical techniques to characterize carbohydrate-modified surfaces, we developed a quantitative X-ray photoelectron spectroscopy (XPS) and surface plasmon resonance imaging (SPR imaging) method to study glycan biosensors. We performed a comparative analysis on the relative coverage of mixed self-assembled monolayers (SAMs) on gold, consisting of a thiol-functionalized trimannoside (Manalpha1,2Manalpha1,2Manalpha-OEG-SH) at varying concentrations (0-100%) mixed separately with two thiol-containing polyethylene glycol oligomers. XPS C1s core level analysis was used to identify the O-C-O functionality unique to the carbohydrate acetal moiety and to separate and quantify the relative coverage of sugar in carbohydrate/OEG mixed SAMs. XPS spectra of the mixed SAMs demonstrated a proportional increase in the acetal signature of the glycan with increasing sugar concentration. To relate surface glycan density with biological function, we carried out a kinetic analysis of Concanavalin A (ConA) binding to SAMs of varying densities of carbohydrate using SPR imaging. We observed protein binding that was highly dependent on both glycan density and the nature of the OEG-thiol used in the mixed self-assembly. These results illustrate the utility of surface analytical techniques such as XPS and SPR in carbohydrate biosensor characterization and optimization.

  11. 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

  12. 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.

  13. 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.

  14. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Section 4(f) evaluations will be coordinated with the Department of Interior, Department of Agriculture, and Department of Housing and Urban Development, and published in the Federal Register for...

  15. Surface and bulk 4f-photoemission spectra of CeIn{sub 3} and CeSn{sub 3}

    SciTech Connect

    Kim, H.; Tjernberg, O.; Chiaia, G.; Kumigashira, H.; Takahashi, T.; Duo, L.; Sakai, O.; Kasaya, M.; Lindau, I.

    1997-07-01

    Resonant photoemission spectroscopy was performed on CeIn{sub 3} and CeSn{sub 3} at the 4d-4f and 3d-4f core thresholds. Using the different surface sensitivity between the two photon energies, surface and bulk 4f-photoemission spectra were derived for both compounds. With the noncrossing approximation of the Anderson impurity model, the 4d-4f resonant spectra together with the surface and bulk spectra were self-consistently analyzed to obtain the microscopic parameters such as the 4f-electron energy and the hybridization strength with conduction electrons. The result shows a substantial difference in these parameters between the surface and the bulk, indicating that it is important to take into account the surface effect in analyzing photoemission spectra of Ce compounds. It is also found that the 4f surface core-level shift is different between CeIn{sub 3} and CeSn{sub 3}. {copyright} {ital 1997} {ital The American Physical Society}

  16. Optical and electrical study of CdZnTe surfaces passivated by KOH and NH4F solutions

    NASA Astrophysics Data System (ADS)

    Zázvorka, J.; Franc, J.; Statelov, M.; Pekárek, J.; Veis, M.; Moravec, P.; Mašek, K.

    2016-12-01

    Performance of CdZnTe-based detectors is highly related to surface preparation. Mechanical polishing, chemical etching and passivation are routinely employed for this purpose. However, the relation between these processes and the detector performance in terms of underlying physical phenomena has not been fully explained. The dynamics and properties of CdZnTe surface oxide layers, created by passivation with KOH and NH4F/H2O2 solutions, were studied by optical ellipsometry and X-ray photoelectron spectroscopy (XPS). Thicknesses and growth rates of the surface oxide layers differed for each of the passivation methods. Leakage currents which influence the final spectral resolution of the detector were measured simultaneously with ellipsometry. Results of both optical and electrical investigation showed the same trends in the time evolution and correlated to each other. NH4F/H2O2 passivation showed to be a method which produces the most desirable properties of the surface oxide layer.

  17. 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

  18. Role of 4 f electrons in crystallographic and magnetic complexity

    NASA Astrophysics Data System (ADS)

    Pathak, Arjun K.; Paudyal, Durga; Mudryk, Yaroslav; Pecharsky, Vitalij K.

    2017-08-01

    The functionality of many magnetic materials critically depends on first manipulating and then taking advantage of highly nonlinear changes of properties that occur during phase transformations. Unique to lanthanides, property-defining 4 f electrons are highly localized and, as commonly accepted, play little to no role in chemical bonding. Yet here we demonstrate that the competition between 4 f -electron energy landscapes of Dy (4 f9 ) and Er (4 f11 ) is the key element of the puzzle required to explain complex interplay of magnetic and structural features observed in E r1 -xD yxC o2 , and likely many other mixed lanthanide systems. Unlike the parent binaries—DyC o2 and ErC o2 —E r1 -xD yxC o2 exhibits two successive magnetostructural transitions: a first order at TC, followed by a second order in the ferrimagnetically ordered state. Supported by first-principles calculations, our results offer new opportunities for targeted design of magnetic materials with multiple functionalities, and also provide a critical insight into the role of 4 f electrons in controlling the magnetism and structure of lanthanide intermetallics.

  19. Role of 4f electrons in crystallographic and magnetic complexity

    DOE PAGES

    Pathak, Arjun K.; Paudyal, Durga; Mudryk, Yaroslav; ...

    2017-08-09

    Here, the functionality of many magnetic materials critically depends on first manipulating and then taking advantage of highly nonlinear changes of properties that occur during phase transformations. Unique to lanthanides, property-defining 4f electrons are highly localized and, as commonly accepted, play little to no role in chemical bonding. Yet here we demonstrate that the competition between 4f-electron energy landscapes of Dy (4f9) and Er (4f11) is the key element of the puzzle required to explain complex interplay of magnetic and structural features observed in Er1–xDyxCo2, and likely many other mixed lanthanide systems. Unlike the parent binaries—DyCo2 and ErCo2—Er1–xDyxCo2 exhibits twomore » successive magnetostructural transitions: a first order at TC, followed by a second order in the ferrimagnetically ordered state. Supported by first-principles calculations, our results offer new opportunities for targeted design of magnetic materials with multiple functionalities, and also provide a critical insight into the role of 4f electrons in controlling the magnetism and structure of lanthanide intermetallics.« less

  20. XPS and SPR Analysis of Glycoarray Surface Density

    PubMed Central

    Dhayal, Marshal; Ratner, Daniel M.

    2009-01-01

    Despite the fact that the carbohydrate microarray has seen increasing use within the field of glycobiology, the surface chemistry of the glycoarray remains largely unexplored. Motivated by the need to develop surface analytical techniques to characterize carbohydrate-modified surfaces, we developed a quantitative X-ray Photoelectron Spectroscopy (XPS) and Surface Plasmon Resonance imaging (SPR imaging) method to study glycan biosensors. We performed a comparative analysis on the relative coverage of mixed self-assembled monolayers (SAMs) on gold, consisting of a thiol-functionalized trimannoside (Manα1,2Manα1,2Manα-OEG-SH) at varying concentrations (0 to 100%) mixed separately with two thiol-containing polyethylene glycol oligomers. XPS C1s core level analysis was used to identify the O-C-O functionality unique to the carbohydrate acetal moiety and to separate and quantify the relative coverage of sugar in carbohydrate/OEG mixed SAMs. XPS spectra of the mixed SAMs demonstrated a proportional increase in the acetal signature of the glycan with increasing sugar concentration. To relate surface glycan density with biological function, we carried out a kinetic analysis of Concanavalin A (ConA) binding to SAMs of varying densities of carbohydrate using SPR imaging. We observed protein-binding that was highly dependent on both glycan density and the nature of the OEG-thiol used in the mixed self-assembly. These results illustrate the utility of surface analytical techniques such as XPS and SPR in carbohydrate biosensor characterization and optimization. PMID:19199748

  1. Surface enhanced single-molecule magnetism involving 4f spin

    SciTech Connect

    Zhang, Yachao

    2016-03-28

    We study the magnetic anisotropy energy (MAE) of the isolated and deposited Eu(C{sub 8}H{sub 8}){sub 2} by first-principles calculations considering the van der Waals correction and the strong correlation effects. We find that both the molecular spin moment and the easy-axis magnetic anisotropy are enhanced upon deposition on Cu(111). We propose a mechanism in terms of the weakened spin polarization of the π-2p orbitals and the induced anisotropic occupations of the 4f orbitals. Our findings pave the way for raising the MAE of 4f-element single-molecule magnets by tailoring the molecule–surface contacts.

  2. Surface enhanced single-molecule magnetism involving 4f spin

    NASA Astrophysics Data System (ADS)

    Zhang, Yachao

    2016-03-01

    We study the magnetic anisotropy energy (MAE) of the isolated and deposited Eu(C8H8)2 by first-principles calculations considering the van der Waals correction and the strong correlation effects. We find that both the molecular spin moment and the easy-axis magnetic anisotropy are enhanced upon deposition on Cu(111). We propose a mechanism in terms of the weakened spin polarization of the π-2p orbitals and the induced anisotropic occupations of the 4f orbitals. Our findings pave the way for raising the MAE of 4f-element single-molecule magnets by tailoring the molecule-surface contacts.

  3. Many-body effects in the 4f x-ray photoelectron spectroscopy of the U5+ and U4+ free ions

    NASA Astrophysics Data System (ADS)

    Ilton, Eugene S.; Bagus, Paul S.

    2005-05-01

    A strictly ab initio many-electron theory was used to calculate the 4f x-ray photoelectron spectroscopy (XPS) of the free U5+ and U4+ ions. The calculations, based on relativistic Dirac-Fock self-consistent field (DF-SCF) and Dirac configuration interaction (DCI) wave functions (WF’s), indicate that the atomic spectra have a considerable multiplet structure. However, the multiplet splitting, which is mainly manifest as a broadening of the 4f5/2 and 4f7/2 lines, is not as strong as for the first-row transition metals. As expected, the U4+ primary peaks are broader and have more associated satellite structure than does U5+ . A comparison of a synthetic spectrum for U4+ with the observed XPS of UO2 indicates that interatomic, solid-state, effects may decrease the multiplet and spin-orbital splitting, relative to the free ion. Notably, the 7eV satellite characteristic of UO2 is absent from the calculated XPS of U4+ .

  4. Trigonal bipyramidal 5d-4f molecules with SMM behavior.

    PubMed

    Saber, Mohamed R; Dunbar, Kim R

    2014-02-28

    A family of trigonal bipyramidal (TBP) 5d-4f cyanide bridged aggregates were synthesized that exhibit slow relaxation of the magnetization below 4 K as indicated by a signal in the out-of-phase ac susceptibility data under zero field.

  5. 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.

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

    PubMed

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

    2015-03-31

    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.

  7. Thorium effect on the oxidation of uranium: Photoelectron spectroscopy (XPS/UPS) and cyclic voltammetry (CV) investigation on (U1 - xThx)O2 (x = 0 to 1) thin films

    NASA Astrophysics Data System (ADS)

    Cakir, P.; Eloirdi, R.; Huber, F.; Konings, R. J. M.; Gouder, T.

    2017-01-01

    Thin films of U1- xThxO2 (x = 0 to 1) have been deposited via reactive DC sputter technique and characterized by X-ray/Ultra-violet Photoelectron Spectroscopy (XPS/UPS), X-ray Powder Diffractometer (XRD) and Cyclic Voltammetry (CV) in order to understand the effect of Thorium on the oxidation mechanism. During the deposition, the competition between uranium and thorium for oxidation showed that thorium has a much higher affinity for oxygen. Deposition conditions, time and temperature were also the subject of this study, to look at the homogeneity and the stability of the films. While core level and valence band spectra were not altered by the time of deposition, temperature was affecting the oxidation state of uranium and the valence band due to the mobility increase of oxygen through the film. X-ray diffraction patterns, core level spectra obtained for U1 - xThxO2 versus the composition showed that lattice parameters follow the Vegard's law and together with the binding energies of U-4f and Th-4f are in good agreement with literature data obtained on bulk compounds. To study the effect of thorium on the oxidation of U1 - xThxO2 films, we used CV experiments at neutral pH of a NaCl solution in contact with air. The results indicated that thorium has an effect on the uranium oxidation as demonstrated by the decrease of the current of the oxidation peak of uranium. XPS measurements made before and after the CV, showed a relative enrichment of thorium at the extent of uranium at the surface supporting the formation at a longer term of a thorium protective layer at the surface of uranium-thorium mixed oxide.

  8. Ab initio theoretical study on the 4f(2) and 4f5d electronic manifolds of cubic defects in CaF2:Pr3+.

    PubMed

    Krośnicki, Marek; Kędziorski, Andrzej; Seijo, Luis; Barandiarán, Zoila

    2014-01-16

    Wave function-based embedded cluster ab initio calculations have been carried out in order to study the 4f(2) and 4f5d energy levels of the cubic substitutional defect of Pr-doped CaF2. The 4f(2) → 4f5d absorption spectrum and 4f5d → 4f(2) emission spectrum have been calculated. The 4f(2 1)S0 level is found to be immersed in the 4f5d(eg) manifold, so that no quantum cutting from (1)S0 can occur and only strong 4f5d(eg) → 4f(2) emission is predicted, which supports previous assumptions made in order to explain results in CaF2:Pr(3+). The details of the 4f(2) → 4f5d(eg) and 4f(2) → 4f5d(t2g) bands of the absorption spectrum are interpreted and assignments are made. The lowest level of the 4f5d(eg) configuration is found to have 80% of singlet character, in opposition to Hund's Rules, and the issue is discussed in detail. The comparison between the experimental 4f5d(eg) → 4f(2) high resolution emission spectrum of the cubic site of CaF2:Pr(3+) and the calculated emission spectra from the two lowest 4f5d(eg) states 1T2u((1)T2u) and 1Eu(1(3)T2u) suggests the possibility that the experimental emission of the cubic Pr defect of CaF2:Pr(3+) is in fact a multiple emission.

  9. XPS studies of chemically modified banana fibers.

    PubMed

    Pothan, L A; Simon, F; Spange, S; Thomas, S

    2006-03-01

    Banana fibers obtained from the sheath of the banana plant (Musa Sapientum) whose major constituent is cellulose were modified using various chemical agents in order to improve their compatibility with the polymer matrix. The change in the surface composition of the raw and chemically modified fiber was investigated using various techniques such as solvatochromism, electrokinetic measurements, and XPS. Surface characterization by XPS showed the presence of numerous elements on the surface of the fiber. Investigation of the surface after alkali treatment on the other hand showed the removal of most of the elements. Silane treatment was found to introduce a considerable amount of silicon on the surface of the fiber. The [O]/[C] ratio was found to decrease in all cases except for the fluorinated and vinyl silane treated fibers. Detailed investigation of the deconvoluted C 1s spectra revealed the change in the percentage atomic concentration of the various elements on the fiber surface. The dissolution of the various surface components by alkali treatment, which was earlier revealed by SEM, was further confirmed by XPS. The XPS results were found to perfectly agree with the solvatochromic and electrokinetic measurements.

  10. Handbook of Monochromatic XPS Spectra, Semiconductors

    NASA Astrophysics Data System (ADS)

    Crist, B. Vincent

    2000-10-01

    This handbook is one of three containing an invaluable collection of research grade XPS Spectra. Each handbook concentrates on a specific family of materials (the elements and their native oxides, semiconductors and polymers) and is entirely self-contained. The introductory section to each handbook includes comprehensive information about the XPS instrument used, the materials and the advanced methods used to collect the spectra. Energy resolution settings, instrument characteristics, energy referencing methods, traceability, energy scale calibration details and transmission function are all reported. Among the many valuable features included in each of these handbooks are: ? All spectra were measured by using AlK monochromatic X-rays ? All spectra were collected in a self-consistent manner to maximise data reliability and quality ? All peaks in the wide spectra are fully annotated and accompanied by detailed atom % tables that report BEs for each of the labelled peaks ? Each high-energy resolution spectrum is peak-fitted and accompanied by detailed tables containing binding energies, FWHMs and relative percentages. In this volume 'Semiconductors' are contained XPS Spectra from a wide range of semiconductive materials and related materials, a rare tool for scientists and analysts in this area. Exclusive features of this volume include: ? Binding energies are accurate to +/- 0.08eV ? Charge compensation was done with a flood-gun mesh-screen system ? Valence band spectra document the occupied density of states (DOS) and the fundamental electronic nature of the semi-conductive materials analysed ? Analyses were done: "as received", "freshly fractured in air", "ion etched" and "chemically treated" ? Alphabetically organised by chemical abbreviations for ease of locating each material This handbook is an invaluable reference for materials scientists and electrical engineers in industry, academia and government laboratories interested in the analysis of semiconductors

  11. 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.

  12. Supramolecular 3d-4f single-molecule magnet architectures.

    PubMed

    Schmitz, Sebastian; van Leusen, Jan; Izarova, Natalya V; Lan, Yanhua; Wernsdorfer, Wolfgang; Kögerler, Paul; Monakhov, Kirill Yu

    2016-10-18

    The nanosized self-assemblies {[{Ln(III)}{H2O⊂CrLn}]2(H2O)} (Ln = Dy, 1 and Tb, 2) based on new 3d-4f mixed-metal coordination topologies are formed via extensive intramolecular hydrogen bonding that is directed by enclosed water molecules. Compounds 1 and 2 show single-molecule magnet characteristics manifested by hysteresis loops up to 1.6 K (Ueff = 8.3 cm(-1)) and 1 K (Ueff = 3.4 cm(-1)), respectively.

  13. XPS study of protein adsorption onto nanocrystalline aluminosilicate microparticles

    NASA Astrophysics Data System (ADS)

    Vanea, E.; Simon, V.

    2011-01-01

    X-ray photoelectron spectroscopy (XPS) was used to study the interaction of two different sized proteins, bovine serum albumin (BSA) and fibrinogen, with an aluminosilicate system containing yttrium and iron that is a potential biomaterial. Serum albumin and fibrinogen are two major plasma proteins and the most relevant proteins adsorbed on the surface of biomaterials in blood contact. The aluminosilicate samples were incubated for several exposure times, up to 24 h, in simulated body fluid enriched with BSA, and in buffered fibrinogen solution. Time dependence of proteins adsorption onto surface of the investigated samples is reflected by the evolution of the new N 1s photoelectron peak and by the modification of C 1s core-level spectra recorded from the samples immersed in protein solution.

  14. Self-assembly of the first discrete 3d-4f-4f triple-stranded helicate.

    PubMed

    Riis-Johannessen, Thomas; Bernardinelli, Gérald; Filinchuk, Yaroslav; Clifford, Sarah; Dalla Favera, Natalia; Piguet, Claude

    2009-06-15

    The connection of an additional bidentate chelating unit at the extremity of a segmental bis-tridentate ligand in L5 provides an unprecedented sequence of binding sites for the self-assembly of heterometallic 3d-4f triple-stranded helicates. Thorough thermodynamic and structural investigations in acetonitrile show the formation of intricate mixtures of complexes when a single type of metal (3d or 4f) is reacted with L5. However, the situation is greatly simplified when Zn(II) (3d-block) and Lu(III) (4f-block) are simultaneously coordinated to L5, thus leading to only two identified species: the target C(3)-symmetrical trinuclear triple-stranded d-f-f helicate HHH-[ZnLu(2)(L5)(3)](8+) and a tetranuclear double-stranded complex [Zn(2)Lu(2)(L5)(2)](10+). Interestingly, the removal of Zn(II) from the former triple-helical complex has only a minor effect on the coordination of Lu(III), and translational autodiffusion coefficients show a simple reduction of the length of the molecular rigid cylinder from L = 2.7 nm in HHH-[ZnLu(2)(L5)(3)](8+) to L = 2.3 nm in HHH-[Lu(2)(L5)(3)](6+). Finally, the complete thermodynamic picture provides five novel stability macroconstants containing information about short-range (ca. 9 A) and long-range (ca. 18 A) intramolecular intermetallic d-f and f-f interactions.

  15. XPS characterization of single crystalline SrLaGa3O7:Nd

    NASA Astrophysics Data System (ADS)

    Iwanowski, R. J.; Heinonen, M. H.; Pracka, I.; Kachniarz, J.

    2013-10-01

    Core-level XPS studies of single crystalline SrLaGa3O7 (SLGO) doped with Nd have been performed for the first time. The detailed analysis of the main XPS core lines of SLGO:Nd included the comparative literature data for the selected oxide compounds containing La and/or Sr, Nd or Ga cations. In particular, the binding energies (BEs) of the Ln 3d5/2 core levels (Ln = La, Nd) in SLGO:Nd were found consistent with the relevant ones for the La- and Nd-based oxides considered, thus indicating that they represent the ground final states of La3+ and Nd3+ ions (respectively) in the crystal lattice after photoexcitation. Analogous consistency has been found for the XPS-derived BEs of the Sr 3d5/2 and Ga 2p3/2 core levels related to the Sr2+ and Ga3+ cationic states in SLGO and the corresponding oxide compounds. Generally, the binding energies of the deep core levels of cations in SLGO:Nd and the other oxides considered are mainly determined by their common oxygen ligand, irrespectively of the crystalline structure.

  16. XPS Study of Some Dilute Magnetic Semiconductors

    NASA Astrophysics Data System (ADS)

    Singhal, R. K.; Sharma, S. C.; Jakhar, N.

    2011-10-01

    In search for room temperature ferromagnetism (RTFM) in nominally doped oxides like ZnO, CeO2, TiO2 etc., several research attempts have been made in recent years. Unfortunately, these could not reach definite conclusions owing to controversial reports and the mechanism of FM ordering continues to remain illusive. We have synthesized Cr and Ni doped (5% each) ZnO bulk samples and studied their structural, electronic and magnetic properties. The magnetization and x-ray photoelectron spectroscopic (XPS) studies on these samples are presented and the electronic structure findings are correlated with magnetic properties.

  17. XPS and NRA investigations during the fabrication of gold nanostructured functionalized screen-printed sensors for the detection of metallic pollutants

    NASA Astrophysics Data System (ADS)

    Jasmin, Jean-Philippe; Miserque, Frédéric; Dumas, Eddy; Vickridge, Ian; Ganem, Jean-Jacques; Cannizzo, Caroline; Chaussé, Annie

    2017-03-01

    An all covalent nanostructured lead sensor was built by the successive grafting of gold nanoparticles and carboxylic ligands at the surface of self-adhesive carbon screen-printed electrodes (SPEs). Surface analysis techniques were used in each step in order to investigate the structuration of this sensor. The self-adhesive surfaces were made from the electrochemical grafting of p-phenylenediamine at the surface of the SPEs via diazonium salts chemistry. The quantity of grafted aniline functions, estimated by Nuclear Reaction Analysis (NRA) performed with p-phenylenediamine labelled with 15N isotope, is in agreement with an almost complete coverage of the electrode surface. The subsequent diazotization of the aniline functions at the surface of the SPEs was performed; X-ray Photoelectron Spectroscopy (XPS) allowed us to consider a quantitative conversion of the aniline functions into diazonium moieties. The spontaneous grafting of gold nanoparticles on the as-obtained reactive surfaces ensures the nanostructuration of the material, and XPS studies showed that the covalent bonding of the gold nanoparticles at the surface of the SPEs induces a change both in the Au-4f (gold nanoparticles) and Cl-2p (carbon ink) core level signals. These unusual observations are explained by an interaction between the carbon ink constituting the substrate and the gold nanoparticles. Heavy and toxic metals are considered of major environmental concern because of their non-biodegradability. In a final step, the grafting of the carboxylic ligands at the surface of the SPEs and an accumulation step in the presence of lead(II) cations allowed us to evidence the interest of nanostructured materials as metallic pollutants sensors.

  18. 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.

  19. Thorough XPS analyses on overlithiated manganese spinel cycled around the 3V plateau

    NASA Astrophysics Data System (ADS)

    Grissa, R.; Martinez, H.; Cotte, S.; Galipaud, J.; Pecquenard, B.; Cras, F. Le

    2017-07-01

    Lithium-rich spinel Li1.2Mn1.8O4 thin film electrodes operated at 3 V/Li+/Li are studied by means of X-ray photoelectron spectroscopy (XPS), mainly on the basis of the evolution of the Mn2p XPS peak during the electrode cycling. The analysis of this core peak has long been debated in literature given its complex character. Based on manganese oxide references, MnO (Mn2+), Mn2O3(Mn3+) and Li2MnO3(Mn4+), we propose a deconvolution method to identify each Mn oxidation state. This method is then used for the deconvolution of Mn2p XPS peaks of bulk lithium-rich spinels Li1+xMn2-xO4 (0 ≤ x ≤ 0.25) for validation before proceeding to the study of cycled Li1.2Mn1.8O4 thin film electrodes. Electrochemical measurements exhibit significant capacity loss during the first cycle. Based on XPS analyses, this phenomenon could be explained by mechanical breakup of parts of the electrode. A stable behavior during subsequent cycles is then observed. The presence of Mn2+ species (XPS) at the most top surface of the electrode and the significant polarization observed during the discharge illustrate the kinetical limitation of the two-phase reaction, despite the reduced thickness of the electrode material.

  20. Copper resinate: an XPS study of degradation

    NASA Astrophysics Data System (ADS)

    Altavilla, C.; Ciliberto, E.

    2006-06-01

    In this paper, we describe an X-ray photoelectron spectroscopy (XPS) study of copper resinate, a transparent green glaze that is coloured by copper salts of resin acids. This pigment was used in Europe in the fifteenth and sixteenth centuries, but it does not seem to be a usual feature of the palette anywhere after the end of the sixteenth century, because its tendency to discolour was already widely known by artists. An essential prerequisite for the restoration of works of art is the understanding of the effects of various climatic parameters on the deterioration process. For this reason, pictorial models of copper resinate in linseed oil, capable of simulating the ancient paintings on mobile supports, were prepared and aged in a climatic chamber, under different conditions such as exposure to UV radiations, humidity and different concentration of chemical pollutants (NO2 and SO2). All the samples were investigated by XPS and the data obtained were evaluated in order to estimate aging effects as well as mechanisms of degradation. On these paint layers damage induced by X-ray irradiation was also verified.

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

    PubMed

    Fujimori, Shin-ichi

    2016-04-20

    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 eV) or high-energy synchrotron radiations (hν >/~ 400 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 CeMIn5(M = Rh, Ir, and Co) and YbRh2Si2 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 U5f compounds such as UFeGa5, their electronic structures can be well-described by the band-structure calculation assuming that all U5f electrons are itinerant. In contrast, the band structures of localized U5f compounds such as UPd3 and UO2 are essentially explained by the localized model that treats U5f electrons as localized core states. In regards to heavy fermion U-based compounds such as the hidden-order compound URu2Si2, their electronic structures exhibit complex behaviors. Their overall band structures are generally well-explained by the band-structure calculation, whereas the states in the vicinity of EF show some deviations due to electron correlation effects. Furthermore, the electronic structures of URu2Si2 in the paramagnetic and hidden-order phases are

  2. 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

  3. 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.

  4. Accessing 4f-states in single-molecule spintronics.

    PubMed

    Fahrendorf, Sarah; Atodiresei, Nicolae; Besson, Claire; Caciuc, Vasile; Matthes, Frank; Blügel, Stefan; Kögerler, Paul; Bürgler, Daniel E; Schneider, Claus M

    2013-01-01

    Magnetic molecules are potential functional units for molecular and supramolecular spintronic devices. However, their magnetic and electronic properties depend critically on their interaction with metallic electrodes. Charge transfer and hybridization modify the electronic structure and thereby influence or even quench the molecular magnetic moment. Yet, detection and manipulation of the molecular spin state by means of charge transport, that is, spintronic functionality, mandates a certain level of hybridization of the magnetic orbitals with electrode states. Here we show how a judicious choice of the molecular spin centres determines these critical molecule-electrode contact characteristics. In contrast to late lanthanide analogues, the 4f-orbitals of single bis(phthalocyaninato)-neodymium(III) molecules adsorbed on Cu(100) can be directly accessed by scanning tunnelling microscopy. Hence, they contribute to charge transport, whereas their magnetic moment is sustained as evident from comparing spectroscopic data with ab initio calculations. Our results showcase how tailoring molecular orbitals can yield all-electrically controlled spintronic device concepts.

  5. 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.

  6. Cytochrome P450-Dependent Catabolism of Vitamin K: ω-Hydroxylation Catalyzed by Human CYP4F2 and CYP4F11

    PubMed Central

    Edson, Katheryne Z.; Prasad, Bhagwat; Unadkat, Jashvant D.; Suhara, Yoshitomo; Okano, Toshio; Guengerich, F. Peter

    2013-01-01

    Vitamin K plays an essential role in many biological processes including blood clotting, maintenance of bone health, and inhibition of arterial calcification. A menaquinone form of vitamin K, MK4, is increasingly recognized for its key roles in mitochondrial electron transport, as a ligand for the nuclear receptor SXR, which controls expression of genes involved in transport and metabolism of endo- and xenobiotics, and as a pharmacotherapeutic in the treatment of osteoporosis. Although cytochrome P450 (CYP) 4F2 activity is recognized as an important determinant of phylloquinone (K1) metabolism, the enzymes involved in menaquinone catabolism have not been studied previously. CYP4F2 and CYP4F11 were expressed and purified and found to be equally efficient as in vitro catalysts of MK4 ω-hydroxylation. CYP4F2, but not CYP4F11, catalyzed sequential metabolism of MK4 to the ω-acid without apparent release of the intermediate aldehyde. The ω-alcohol could also be metabolized to the acid by microsomal NAD+-dependent alcohol and aldehyde dehydrogenases. LC-MS/MS analysis of trypsinized human liver microsomes (using surrogate peptide approach) revealed mean concentrations of CYP4F2 and CYP4F11 to be 14.3 and 8.4 pmol/mg protein, respectively. Microsomal MK4 ω-hydroxylation activities correlated with the CYP4F2 V433M genotype but not CYP4F11 D446N genotype. Collectively, these data expand the lexicon of vitamin K ω-hydroxylases to include the ‘orphan’ P450 CYP4F11 and identify a common variant, CYP4F2 (rs2108622), as a major pharmacogenetic variable influencing MK4 catabolism. PMID:24138531

  7. 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

  8. Disruption of Mouse Cytochrome P450 4f14 (Cyp4f14 Gene) Causes Severe Perturbations in Vitamin E Metabolism*

    PubMed Central

    Bardowell, Sabrina A.; Duan, Faping; Manor, Danny; Swanson, Joy E.; Parker, Robert S.

    2012-01-01

    Vitamin E is a family of naturally occurring and structurally related lipophilic antioxidants, one of which, α-tocopherol (α-TOH), selectively accumulates in vertebrate tissues. The ω-hydroxylase cytochrome P450–4F2 (CYP4F2) is the only human enzyme shown to metabolize vitamin E. Using cDNA cloning, cell culture expression, and activity assays, we identified Cyp4f14 as a functional murine ortholog of CYP4F2. We then investigated the effect of Cyp4f14 deletion on vitamin E metabolism and status in vivo. Cyp4f14-null mice exhibited substrate-specific reductions in liver microsomal vitamin E-ω-hydroxylase activity ranging from 93% (γ-TOH) to 48% (γ-tocotrienol). In vivo data obtained from metabolic cage studies showed whole-body reductions in metabolism of γ-TOH of 90% and of 68% for δ- and α-TOH. This metabolic deficit in Cyp4f14−/− mice was partially offset by increased fecal excretion of nonmetabolized tocopherols and of novel ω-1- and ω-2-hydroxytocopherols. 12′-OH-γ-TOH represented 41% of whole-body production of γ-TOH metabolites in Cyp4f14−/− mice fed a soybean oil diet. Despite these counterbalancing mechanisms, Cyp4f14-null mice fed this diet for 6 weeks hyper-accumulated γ-TOH (2-fold increase over wild-type littermates) in all tissues and appeared normal. We conclude that CYP4F14 is the major but not the only vitamin E-ω-hydroxylase in mice. Its disruption significantly impairs whole-body vitamin E metabolism and alters the widely conserved phenotype of preferential tissue deposition of α-TOH. This model animal and its derivatives will be valuable in determining the biological actions of specific tocopherols and tocotrienols in vivo. PMID:22665481

  9. Copper Causes Regiospecific Formation of C4F8-Containing Six-Membered Rings and their Defluorination/Aromatization to C4F4-Containing Rings in Triphenylene/1,4-C4F8I2 Reactions

    SciTech Connect

    Rippy, Kerry C.; Bukovsky, Eric V.; Clikeman, Tyler T.; Chen, Yu-Sheng; Hou, Gao-Lei; Wang, Xue B.; Popov, Alexey; Boltalina, Olga V.; Strauss, Steven H.

    2016-01-18

    The presence of Cu in reactions of triphenylene (TRPH) and 1,4-C4F8I2 at 360 °C led to regiospecific substitution of TRPH ortho C(β) atoms to form C4F8-containing rings, completely suppressing substitution on C(α) atoms. In addition, Cu caused selective reductive-defluorination/aromatization (RD/A) to form C4F4- containing aromatic rings. Without Cu, the reactions of TRPH and 1,4- C4F8I2 were not regiospecific and no RD/A was observed. These results, supported by DFT calculations, are the first examples of Cupromoted (i) regiospecific perfluoroannulation, (ii) preparative C–F activation, and (iii) RD/A. HPLC-purified products were characterized by X-ray diffraction, low-temperature PES, and 1H/19F NMR.

  10. Use of XPS to Quantify Thickness of Coatings on Nanoparticles

    SciTech Connect

    Baer, Donald R.; Wang, Yung-Cheng; Castner, David G.

    2016-03-01

    XPS and other surface sensitive methods are being increasingly used to extract quantitative information about organic and inorganic coatings and contamination on nanoparticles. The extraction of coating thickness information requires combining known information about particle diameter from other measurements, such as electron microscopy, combined with a model that includes the physical processes associated with XPS, including electron path lengths, and particle geometry. Advantages of using XPS include the sensitivity to very thin coatings (or surface contamination) and the abillity to extract important information about organic layers. Single particle information from electron microsocpy combined XPS sensitivity to determine an average coating structure and composition make a powerful combination for nanoparticle anlaysis.

  11. XPS study on silica bismuthate glasses and glass ceramics

    NASA Astrophysics Data System (ADS)

    Simon, V.; Todea, M.; Takács, A. F.; Neumann, M.; Simon, S.

    2007-01-01

    X-ray photoelectron spectroscopy (XPS) was used to evidence the effect of the Bi 2O 3 to SiO 2 ratio and of partial crystallisation on the electronic charge density around the atoms entering silica-bismuthate glasses of nominal composition 0.01Fe 2O 3ṡ0.99[ xSiO 2ṡ(100- x)Bi 2O 3] with 10≤x≤60 mol%. The core level spectra show significant composition dependent changes in binding energy, and the full width at half maximum of photoelectron peaks both of cations and of oxygen atoms. The analysis reveals changes in electron density correlated with the ionic and covalent character of the samples. The shift in binding energy suggests charge transfer from silicon and oxygen atoms to bismuth atoms. Contrary to the expected behaviour in conventional silicate oxide systems, the results indicate an increase of ionicity for silicon and of covalency for bismuth atoms. The same evolution of ionicity/covalency is observed after partial crystallisation.

  12. Transcription factor E4F1 is essential for epidermal stem cell maintenance and skin homeostasis

    PubMed Central

    Lacroix, Matthieu; Caramel, Julie; Goguet-Rubio, Perrine; Linares, Laetitia K.; Estrach, Soline; Hatchi, Elodie; Rodier, Geneviève; Lledo, Gwendaline; de Bettignies, Carine; Thépot, Amélie; Deraison, Céline; Chébli, Karim; Hainaut, Pierre; Dubus, Pierre; Sardet, Claude; Le Cam, Laurent

    2010-01-01

    A growing body of evidence suggests that the multifunctional protein E4F1 is involved in signaling pathways that play essential roles during normal development and tumorigenesis. We generated E4F1 conditional knockout mice to address E4F1 functions in vivo in newborn and adult skin. E4F1 inactivation in the entire skin or in the basal compartment of the epidermis induces skin homeostasis defects, as evidenced by transient hyperplasia in the interfollicular epithelium and alteration of keratinocyte differentiation, followed by loss of cellularity in the epidermis and severe skin ulcerations. E4F1 depletion alters clonogenic activity of epidermal stem cells (ESCs) ex vivo and ends in exhaustion of the ESC pool in vivo, indicating that the lesions observed in the E4F1 mutant skin result, at least in part, from cell-autonomous alterations in ESC maintenance. The clonogenic potential of E4F1 KO ESCs is rescued by Bmi1 overexpression or by Ink4a/Arf or p53 depletion. Skin phenotype of E4F1 KO mice is also delayed in animals with Ink4a/Arf and E4F1 compound gene deficiencies. Our data identify a regulatory axis essential for ESC-dependent skin homeostasis implicating E4F1 and the Bmi1–Arf–p53 pathway. PMID:21088222

  13. E4F1 deficiency results in oxidative stress–mediated cell death of leukemic cells

    PubMed Central

    Hatchi, Elodie; Rodier, Genevieve; Lacroix, Matthieu; Caramel, Julie; Kirsh, Olivier; Jacquet, Chantal; Schrepfer, Emilie; Lagarrigue, Sylviane; Linares, Laetitia Karine; Lledo, Gwendaline; Tondeur, Sylvie; Dubus, Pierre

    2011-01-01

    The multifunctional E4F1 protein was originally discovered as a target of the E1A viral oncoprotein. Growing evidence indicates that E4F1 is involved in key signaling pathways commonly deregulated during cell transformation. In this study, we investigate the influence of E4F1 on tumorigenesis. Wild-type mice injected with fetal liver cells from mice lacking CDKN2A, the gene encoding Ink4a/Arf, developed histiocytic sarcomas (HSs), a tumor originating from the monocytic/macrophagic lineage. Cre-mediated deletion of E4F1 resulted in the death of HS cells and tumor regression in vivo and extended the lifespan of recipient animals. In murine and human HS cell lines, E4F1 inactivation resulted in mitochondrial defects and increased production of reactive oxygen species (ROS) that triggered massive cell death. Notably, these defects of E4F1 depletion were observed in HS cells but not healthy primary macrophages. Short hairpin RNA–mediated depletion of E4F1 induced mitochondrial defects and ROS-mediated death in several human myeloid leukemia cell lines. E4F1 protein is overexpressed in a large subset of human acute myeloid leukemia samples. Together, these data reveal a role for E4F1 in the survival of myeloid leukemic cells and support the notion that targeting E4F1 activities might have therapeutic interest. PMID:21708927

  14. E4F1 deficiency results in oxidative stress-mediated cell death of leukemic cells.

    PubMed

    Hatchi, Elodie; Rodier, Genevieve; Lacroix, Matthieu; Caramel, Julie; Kirsh, Olivier; Jacquet, Chantal; Schrepfer, Emilie; Lagarrigue, Sylviane; Linares, Laetitia Karine; Lledo, Gwendaline; Tondeur, Sylvie; Dubus, Pierre; Sardet, Claude; Le Cam, Laurent

    2011-07-04

    The multifunctional E4F1 protein was originally discovered as a target of the E1A viral oncoprotein. Growing evidence indicates that E4F1 is involved in key signaling pathways commonly deregulated during cell transformation. In this study, we investigate the influence of E4F1 on tumorigenesis. Wild-type mice injected with fetal liver cells from mice lacking CDKN2A, the gene encoding Ink4a/Arf, developed histiocytic sarcomas (HSs), a tumor originating from the monocytic/macrophagic lineage. Cre-mediated deletion of E4F1 resulted in the death of HS cells and tumor regression in vivo and extended the lifespan of recipient animals. In murine and human HS cell lines, E4F1 inactivation resulted in mitochondrial defects and increased production of reactive oxygen species (ROS) that triggered massive cell death. Notably, these defects of E4F1 depletion were observed in HS cells but not healthy primary macrophages. Short hairpin RNA-mediated depletion of E4F1 induced mitochondrial defects and ROS-mediated death in several human myeloid leukemia cell lines. E4F1 protein is overexpressed in a large subset of human acute myeloid leukemia samples. Together, these data reveal a role for E4F1 in the survival of myeloid leukemic cells and support the notion that targeting E4F1 activities might have therapeutic interest.

  15. Transcription factor E4F1 is essential for epidermal stem cell maintenance and skin homeostasis.

    PubMed

    Lacroix, Matthieu; Caramel, Julie; Goguet-Rubio, Perrine; Linares, Laetitia K; Estrach, Soline; Hatchi, Elodie; Rodier, Geneviève; Lledo, Gwendaline; de Bettignies, Carine; Thépot, Amélie; Deraison, Céline; Chébli, Karim; Hovnanian, Alain; Hainaut, Pierre; Dubus, Pierre; Sardet, Claude; Le Cam, Laurent

    2010-12-07

    A growing body of evidence suggests that the multifunctional protein E4F1 is involved in signaling pathways that play essential roles during normal development and tumorigenesis. We generated E4F1 conditional knockout mice to address E4F1 functions in vivo in newborn and adult skin. E4F1 inactivation in the entire skin or in the basal compartment of the epidermis induces skin homeostasis defects, as evidenced by transient hyperplasia in the interfollicular epithelium and alteration of keratinocyte differentiation, followed by loss of cellularity in the epidermis and severe skin ulcerations. E4F1 depletion alters clonogenic activity of epidermal stem cells (ESCs) ex vivo and ends in exhaustion of the ESC pool in vivo, indicating that the lesions observed in the E4F1 mutant skin result, at least in part, from cell-autonomous alterations in ESC maintenance. The clonogenic potential of E4F1 KO ESCs is rescued by Bmi1 overexpression or by Ink4a/Arf or p53 depletion. Skin phenotype of E4F1 KO mice is also delayed in animals with Ink4a/Arf and E4F1 compound gene deficiencies. Our data identify a regulatory axis essential for ESC-dependent skin homeostasis implicating E4F1 and the Bmi1-Arf-p53 pathway.

  16. 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.

  17. XPS and XRD studies of samples from the natural fission reactors in the Oklo uranium deposits

    SciTech Connect

    Sunder, S.; Miller, N.H.; Duclos, A.M.

    1994-12-31

    Mineral samples from the natural fission reactors 10 and 13 in the Oklo uranium deposits were studied using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) to gain information about the long-term behaviour of UO{sub 2} fuel in a geological disposal vault. Two samples from reactor zone 10 (samples No. D81N-190292 and D73-88) and one sample from reactor zone 13 (sample No. SD37-S2/CD) were analysed. Low-resolution XPS spectra were recorded to determine the major elements present in the ore. High-resolution spectra were recorded to gain information about the chemical state of the elements present in the mineral samples. The samples show low values for the U{sup 6+}/U{sup 4+} ratio. The oxidation state of uranium in these samples is even lower than that in U{sub 4}O{sub 9}.The binding energies of the Pb 4f bands indicate most of the Pb is in the +2 oxidation state in these samples. The C ls band indicates the presence of organic carbon. XRD analysis shows that the main uranium-bearing phase is uraninite and lead is present mainly as galena. The significance of the results for nuclear fuel waste management is discussed.

  18. Wheat germ poly(A) binding protein enhances the binding affinity of eukaryotic initiation factor 4F and (iso)4F for cap analogues.

    PubMed

    Wei, C C; Balasta, M L; Ren, J; Goss, D J

    1998-02-17

    Most eukaryotic mRNAs contain a 5' cap (m7GppX) and a 3' poly(A) tail to increase synergistically the translational efficiency. Recently, the poly(A) binding protein (PABP) and cap-binding protein, eIF-4F, were found to interact [Le et al. (1997) J. Biol. Chem. 272, 16247-16255; Tarun and Sachs (1996) EMBO J. 15, 7168-7177]. These data suggest that PABP may exert its effect on translational efficiency either by increasing the formation of initiation factor-mRNA complex or by enhancing ribosome recycling. To investigate the functional consequences of these interactions, the fluorescent cap analogue, ant-m7GTP, which is an environmentally sensitive fluorescent probe [Ren and Goss (1996) Nucleic Acids Res. 24, 3629-3634] was used to investigate the cap-binding affinity. Our data show that the binding of eIF-(iso)4F or eIF-4F to cap analogue enhanced their binding affinity toward PABP approximately 40-fold. Similarly, the eIF-4F/PABP or eIF-(iso)4F/PABP complexes show a 40-fold enhancement of cap analogue binding as compared to eIF-4F or eIF-(iso)4F alone. At least part of the enhancement of the translational initiation by PABP can be accounted for by direct changes in cap-binding affinity. The interactions of these components also suggest a mechanism whereby the poly(A) tail is brought into close proximity with m7G cap. This effect was examined by fluorescence energy transfer, and it was determined that the PABP/eIF-4F complex could bind both poly(A) and 5' cap simultaneously.

  19. 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

    2013-09-07

    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.

  20. 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.

  1. Etching of porous and solid SiO2 in Ar /c-C4F8, O2/c-C4F8 and Ar /O2/c-C4F8 plasmas

    NASA Astrophysics Data System (ADS)

    Sankaran, Arvind; Kushner, Mark J.

    2005-01-01

    C-C4F8-based plasmas are used for selective etching of high aspect ratio (HAR) trenches in SiO2 and other dielectrics for microelectronics fabrication. Additives such as Ar and O2 are often used to optimize the process. Understanding the fundamentals of these processes is critical to extending technologies developed for solid SiO2 to porous SiO2, as used in low-dielectric constant insulators. To investigate these issues, reaction mechanisms developed for etching of solid and porous SiO2 in fluorocarbon plasmas and for etching of organic polymers in O2 plasmas have been incorporated into a feature profile model capable of addressing two-phase porous materials. The reaction mechanism was validated by comparison to experiments for blanket etching of solid and porous SiO2 in Ar /c-C4F8 and O2/c-C4F8 plasmas using inductively coupled plasma reactors. We found that the blanket etch rates of both solid and porous SiO2 had maxima as a function of Ar and O2 addition to c-C4F8 at mole fractions corresponding to an optimum thickness of the overlying polymer layer. Larger Ar and O2 additions were required to optimize the etch rate for porous SiO2. Whereas etch stops occurred during etching of HAR features in solid and porous SiO2 using pure c-C4F8 plasmas, Ar and O2 addition facilitated etching by reducing the polymer thickness, though with some loss of critical dimensions. Mixtures of Ar /O2/c-C4F8 can be used to manage this tradeoff.

  2. Electronic structure of β-RbNd(MoO4)2 by XPS and XES

    NASA Astrophysics Data System (ADS)

    Atuchin, V. V.; Khyzhun, O. Y.; Chimitova, O. D.; Molokeev, M. S.; Gavrilova, T. A.; Bazarov, B. G.; Bazarova, J. G.

    2015-02-01

    β-RbNd(MoO4)2 microplates have been prepared by the multistage solid state synthesis method. The phase composition and micromorphology of the final product have been evaluated by XRD and SEM methods. The electronic structure of β-RbNd(MoO4)2 molybdate has been studied employing the X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). For the molybdate, the XPS core-level and valence-band spectra, as well as XES bands representing energy distribution of the Mo 4d- and O 2p-like states, have been measured. It has been established that the O 2p-like states contribute mainly to the upper portion of the valence band with also significant contributions throughout the whole valence-band region. The Mo 4D-like states contribute mainly to a lower valence band portion.

  3. 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.

  4. E4F1 dysfunction results in autophagic cell death in myeloid leukemic cells

    PubMed Central

    Hatchi, Elodie; Rodier, Geneviève; Sardet, Claude

    2011-01-01

    The multifunctional E4F1 protein was originally identified as a cellular target of the E1A adenoviral oncoprotein. Although E4F1 is implicated in several key oncogenic pathways, its roles in tumorigenesis remain unclear. Using a genetically engineered mouse model of myeloid leukemia (histiocytic sarcomas, HS) based on the genetic inactivation of the tumor suppressor Ink4a/Arf locus, we have recently unraveled an unsuspected function of E4F1 in the survival of leukemic cells. In vivo, genetic ablation of E4F1 in established myeloid tumors results in tumor regression. E4F1 inactivation results in a cascade of alterations originating from dysfunctional mitochondria that induce increased reactive oxygen species (ROS) levels and ends in massive autophagic cell death in HS transformed, but not normal myeloid cells. E4F1 depletion also induces cell death in various human myeloid leukemic cell lines, including acute myeloid leukemic (AML) cell lines. Interestingly, the E4F1 protein is overexpressed in a large proportion of human AML samples. These data provide new insights into E4F1-associated survival functions implicated in tumorigenesis and could open the path for new therapeutic strategies. PMID:22024746

  5. L-4F Alters Hyperlipidemic (but not Normal) Mouse Plasma to Reduce Platelet Aggregation

    PubMed Central

    Buga, Georgette M.; Navab, Mohamad; Imaizumi, Satoshi; Reddy, Srinivasa T.; Yekta, Babak; Hough, Greg; Chanslor, Shawn; Anantharamaiah, G.M.; Fogelman, Alan M.

    2010-01-01

    Objective Hyperlipidemia is associated with platelet hyper-reactivity. We hypothesized that L-4F, an apoA-I mimetic peptide, would inhibit platelet aggregation in hyperlipidemic mice. Methods and Results Injecting L-4F into apoE null and LDL receptor null mice resulted in a significant reduction in platelet aggregation in response to agonists but there was no reduction in platelet aggregation after injection of L-4F into wild-type (WT) mice. Consistent with these results, injection of L-4F into apoE null mice prolonged bleeding time but not in WT mice. Incubating L-4F in vitro with apoE null platelet rich plasma also resulted in decreased platelet aggregation. However, incubating washed platelets from either apoE null or WT mice with L-4F did not alter aggregation. Compared to wild-type mice, unstimulated platelets from apoE null mice contained significantly more 12-HETE, thromboxane A2 (TXA2), prostaglandins D2 (PGD2) and E2 (PGE2). In response to agonists, platelets from L-4F treated apoE null mice formed significantly less TXA2, PGD2 PGE2, and 12-HETE. Conclusions By binding plasma oxidized lipids that cause platelet hyper-reactivity in hyperlipidemic mice, L-4F decreases platelet aggregation. PMID:19965777

  6. E4F1 dysfunction results in autophagic cell death in myeloid leukemic cells.

    PubMed

    Hatchi, Elodie; Rodier, Geneviève; Sardet, Claude; Le Cam, Laurent

    2011-12-01

    The multifunctional E4F1 protein was originally identified as a cellular target of the E1A adenoviral oncoprotein. Although E4F1 is implicated in several key oncogenic pathways, its roles in tumorigenesis remain unclear. Using a genetically engineered mouse model of myeloid leukemia (histiocytic sarcomas, HS) based on the genetic inactivation of the tumor suppressor Ink4a/Arf locus, we have recently unraveled an unsuspected function of E4F1 in the survival of leukemic cells. In vivo, genetic ablation of E4F1 in established myeloid tumors results in tumor regression. E4F1 inactivation results in a cascade of alterations originating from dysfunctional mitochondria that induce increased reactive oxygen species (ROS) levels and ends in massive autophagic cell death in HS transformed, but not normal myeloid cells. E4F1 depletion also induces cell death in various human myeloid leukemic cell lines, including acute myeloid leukemic (AML) cell lines. Interestingly, the E4F1 protein is overexpressed in a large proportion of human AML samples. These data provide new insights into E4F1-associated survival functions implicated in tumorigenesis and could open the path for new therapeutic strategies.

  7. 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.

  8. 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.

  9. Vascular characterization of mice with endothelial expression of cytochrome P450 4F2.

    PubMed

    Cheng, Jennifer; Edin, Matthew L; Hoopes, Samantha L; Li, Hong; Bradbury, J Alyce; Graves, Joan P; DeGraff, Laura M; Lih, Fred B; Garcia, Victor; Shaik, Jafar Sadik B; Tomer, Kenneth B; Flake, Gordon P; Falck, John R; Lee, Craig R; Poloyac, Samuel M; Schwartzman, Michal L; Zeldin, Darryl C

    2014-07-01

    Cytochrome P450 (CYP) 4A and 4F enzymes metabolize arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE). Although CYP4A-derived 20-HETE is known to have prohypertensive and proangiogenic properties, the effects of CYP4F-derived metabolites are not well characterized. To investigate the role of CYP4F2 in vascular disease, we generated mice with endothelial expression of human CYP4F2 (Tie2-CYP4F2-Tr). LC/MS/MS analysis revealed 2-foldincreases in 20-HETE levels in tissues and endothelial cells (ECs), relative to wild-type (WT) controls. Tie2-CYP4F2-Tr ECs demonstrated increases in growth (267.1 ± 33.4 vs. 205.0 ± 13% at 48 h) and tube formation (7.7 ± 1.1 vs. 1.6 ± 0.5 tubes/field) that were 20-HETE dependent and associated with up-regulation of prooxidant NADPH oxidase and proangiogenic VEGF. Increases in VEGF and NADPH oxidase levels were abrogated by inhibitors of NADPH oxidase and MAPK, respectively, suggesting the possibility of crosstalk between pathways. Interestingly, IL-6 levels in Tie2-CYP4F2-Tr mice (18.6 ± 2.7 vs. 7.9 ± 2.7 pg/ml) were up-regulated via NADPH oxidase- and 20-HETE-dependent mechanisms. Although Tie2-CYP4F2-Tr aortas displayed increased vasoconstriction, vasorelaxation and blood pressure were unchanged. Our findings indicate that human CYP4F2 significantly increases 20-HETE production, CYP4F2-derived 20-HETE mediates EC proliferation and angiogenesis via VEGF- and NADPH oxidase-dependent manners, and the Tie2-CYP4F2-Tr mouse is a novel model for examining the pathophysiological effects of CYP4F2-derived 20-HETE in the vasculature.-Cheng, J., Edin, M. L., Hoopes, S. L., Li, H., Bradbury, J. A., Graves, J. P., DeGraff, L. M., Lih, F. B., Garcia, V., Shaik, J. S. B., Tomer, K. B., Flake, G. P., Falck, J. R., Lee, C. R., Poloyac, S. M., Schwartzman, M. L., Zeldin, D. C. Vascular characterization of mice with endothelial expression of cytochrome P450 4F2.

  10. XPS investigation of titanium contact formation to ZnO nanowires.

    PubMed

    Barnett, Chris J; Castaing, Ambroise; Jones, Daniel R; Lewis, Aled R; Jenkins, Lewys J; Cobley, Richard J; Maffeis, Thierry G G

    2017-02-24

    Ti is often used to form an initial Ohmic interface between ZnO and Au due to its low work function, and the TiO2/ZnO heterojunction is also of great importance for many practical applications of nanoparticles. Here, Ti has been controllably deposited onto hydrothermally grown ZnO nanowires and the formation of metal-semiconductor contact has been investigated using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and scanning electron microscopy. XPS results showed that that the Ti initially reacts with surface oxygen species to form TiO2, and further deposition results in the formation of oxides with oxidation state numbers lower than four, and eventually metallic Ti on top of the TiO2. The formation of TiC was also observed. XPS showed that the onset of metallic Ti coincided with a Zn 3p core level shift to lower binding energy, indicating upwards band bending and the formation of a rectifying contact. Annealing caused a near-complete conversion of the metallic Ti to TiO2 and caused the Zn 3p to shift back to its original higher binding energy, resulting in downwards band bending and a more Ohmic contact. PL measurements showed that the optical properties of the nanowires are not affected by the contact formation.

  11. XPS investigation of titanium contact formation to ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Barnett, Chris J.; Castaing, Ambroise; Jones, Daniel R.; Lewis, Aled R.; Jenkins, Lewys J.; Cobley, Richard J.; Maffeis, Thierry G. G.

    2017-02-01

    Ti is often used to form an initial Ohmic interface between ZnO and Au due to its low work function, and the TiO2/ZnO heterojunction is also of great importance for many practical applications of nanoparticles. Here, Ti has been controllably deposited onto hydrothermally grown ZnO nanowires and the formation of metal-semiconductor contact has been investigated using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and scanning electron microscopy. XPS results showed that that the Ti initially reacts with surface oxygen species to form TiO2, and further deposition results in the formation of oxides with oxidation state numbers lower than four, and eventually metallic Ti on top of the TiO2. The formation of TiC was also observed. XPS showed that the onset of metallic Ti coincided with a Zn 3p core level shift to lower binding energy, indicating upwards band bending and the formation of a rectifying contact. Annealing caused a near-complete conversion of the metallic Ti to TiO2 and caused the Zn 3p to shift back to its original higher binding energy, resulting in downwards band bending and a more Ohmic contact. PL measurements showed that the optical properties of the nanowires are not affected by the contact formation.

  12. A New Marmoset P450 4F12 Enzyme Expressed in Small Intestines and Livers Efficiently Metabolizes Antihistaminic Drug Ebastine.

    PubMed

    Uehara, Shotaro; Uno, Yasuhiro; Yuki, Yukako; Inoue, Takashi; Sasaki, Erika; Yamazaki, Hiroshi

    2016-06-01

    Common marmosets (Callithrix jacchus) are attracting attention as animal models in preclinical studies for drug development. However, cytochrome P450s (P450s), major drug-metabolizing enzymes, have not been fully identified and characterized in marmosets. In this study, based on the four novel P450 4F genes found on the marmoset genome, we successfully isolated P450 4F2, 4F3B, 4F11, and 4F12 cDNAs in marmoset livers. Deduced amino acid sequences of the four marmoset P450 4F forms exhibited high sequence identities (87%-93%) to the human and cynomolgus monkey P450 4F homologs. Marmoset P450 4F3B and 4F11 mRNAs were predominantly expressed in livers, whereas marmoset P450 4F2 and 4F12 mRNAs were highly expressed in small intestines and livers. Four marmoset P450 4F proteins heterologously expressed in Escherichia coli catalyzed the ω-hydroxylation of leukotriene B4 In addition, marmoset P450 4F12 effectively catalyzed the hydroxylation of antiallergy drug ebastine, a human P450 2J/4F probe substrate. Ebastine hydroxylation activities by small intestine and liver microsomes from marmosets and cynomolgus monkeys showed greatly higher values than those of humans. Ebastine hydroxylation activities by marmoset and cynomolgus monkey small intestine microsomes were inhibited (approximately 60%) by anti-P450 4F antibodies, unlike human small intestine microsomes, suggesting that contribution of P450 4F enzymes for ebastine hydroxylation in the small intestine might be different between marmosets/cynomolgus monkeys and humans. These results indicated that marmoset P450 4F2, 4F3B, 4F11, and 4F12 were expressed in livers and/or small intestines and were functional in the metabolism of endogenous and exogenous compounds, similar to those of cynomolgus monkeys and humans.

  13. E4F1-mediated control of pyruvate dehydrogenase activity is essential for skin homeostasis.

    PubMed

    Goguet-Rubio, Perrine; Seyran, Berfin; Gayte, Laurie; Bernex, Florence; Sutter, Anne; Delpech, Hélène; Linares, Laetitia Karine; Riscal, Romain; Repond, Cendrine; Rodier, Geneviève; Kirsh, Olivier; Touhami, Jawida; Noel, Jean; Vincent, Charles; Pirot, Nelly; Pavlovic, Guillaume; Herault, Yann; Sitbon, Marc; Pellerin, Luc; Sardet, Claude; Lacroix, Matthieu; Le Cam, Laurent

    2016-09-27

    The multifunctional protein E4 transcription factor 1 (E4F1) is an essential regulator of epidermal stem cell (ESC) maintenance. Here, we found that E4F1 transcriptionally regulates a metabolic program involved in pyruvate metabolism that is required to maintain skin homeostasis. E4F1 deficiency in basal keratinocytes resulted in deregulated expression of dihydrolipoamide acetyltransferase (Dlat), a gene encoding the E2 subunit of the mitochondrial pyruvate dehydrogenase (PDH) complex. Accordingly, E4f1 knock-out (KO) keratinocytes exhibited impaired PDH activity and a redirection of the glycolytic flux toward lactate production. The metabolic reprogramming of E4f1 KO keratinocytes associated with remodeling of their microenvironment and alterations of the basement membrane, led to ESC mislocalization and exhaustion of the ESC pool. ShRNA-mediated depletion of Dlat in primary keratinocytes recapitulated defects observed upon E4f1 inactivation, including increased lactate secretion, enhanced activity of extracellular matrix remodeling enzymes, and impaired clonogenic potential. Altogether, our data reveal a central role for Dlat in the metabolic program regulated by E4F1 in basal keratinocytes and illustrate the importance of PDH activity in skin homeostasis.

  14. Computational Study on Dissociation Properties of C4F6 Molecules

    NASA Astrophysics Data System (ADS)

    Choi, Heechol; Song, Mi-Young; Yoon, Jung-Sik; Plasma Fundamental Technology Research Team

    2016-09-01

    Saturated or unsaturated perfluorocarbons(PFCs) have been used extensively in dry etching processes due to their relatively low global warming potential and their high CF2 radical levels in commercial plasma processes. Many experimental and theoretical studies of these species have been performed for useful information about physical and chemical properties of PFCs. Recently, it was reported that the ωB97X-D/aVTZ method is strongly recommended as the best practical density functional theory (DFT) for rigorous and extensive studies of PFCs because this theoretical level shows the high performance and reliability especially for van der Waals interactions. Among various PFCs, this study focuses on C4F6 molecules including c-C4F6, 1,3-C4F6, and 2-C4F6 isomers. All the feasible isomerization and dissociation paths of C4F6 molecules were investigated mainly at the ωB97X-D/aVTZ level. Their reaction rate constants were computed by using variational transition-state theory for a deep insight into C4F6's reaction mechanism. Fates and roles of C4F6 molecules and their fragments in plasma phases could be explained based on our theoretical results and data. This work was supported by R&D Program of Plasma Convergence & Fundamental Research through NFRI of Korea funded by the Government funds.

  15. E4F1-mediated control of pyruvate dehydrogenase activity is essential for skin homeostasis

    PubMed Central

    Goguet-Rubio, Perrine; Seyran, Berfin; Gayte, Laurie; Sutter, Anne; Delpech, Hélène; Linares, Laetitia Karine; Riscal, Romain; Repond, Cendrine; Rodier, Geneviève; Touhami, Jawida; Noel, Jean; Vincent, Charles; Pirot, Nelly; Herault, Yann; Pellerin, Luc; Sardet, Claude; Lacroix, Matthieu; Le Cam, Laurent

    2016-01-01

    The multifunctional protein E4 transcription factor 1 (E4F1) is an essential regulator of epidermal stem cell (ESC) maintenance. Here, we found that E4F1 transcriptionally regulates a metabolic program involved in pyruvate metabolism that is required to maintain skin homeostasis. E4F1 deficiency in basal keratinocytes resulted in deregulated expression of dihydrolipoamide acetyltransferase (Dlat), a gene encoding the E2 subunit of the mitochondrial pyruvate dehydrogenase (PDH) complex. Accordingly, E4f1 knock-out (KO) keratinocytes exhibited impaired PDH activity and a redirection of the glycolytic flux toward lactate production. The metabolic reprogramming of E4f1 KO keratinocytes associated with remodeling of their microenvironment and alterations of the basement membrane, led to ESC mislocalization and exhaustion of the ESC pool. ShRNA-mediated depletion of Dlat in primary keratinocytes recapitulated defects observed upon E4f1 inactivation, including increased lactate secretion, enhanced activity of extracellular matrix remodeling enzymes, and impaired clonogenic potential. Altogether, our data reveal a central role for Dlat in the metabolic program regulated by E4F1 in basal keratinocytes and illustrate the importance of PDH activity in skin homeostasis. PMID:27621431

  16. Photo and thermoluminescence of KMgSO4 F: Ce and :Mn phosphors.

    PubMed

    Poddar, Anuradha; Gedam, S C; Dhoble, S J

    2015-06-01

    KMgSO4 F:Ce and KMgSO4 F:Mn phosphors were prepared by a wet chemical method and studied for their photoluminescence (PL) and thermoluminescence (TL) characteristics. PL emission of KMgSO4 F:Ce peaked at around 440 nm for the excitation at 377 nm due to 5d → 4f transition, while KMgSO4 F:Mn had a peak at 540 nm for an excitation at 363 nm and 247 nm due to (4) T1g  → (6) A1g transition. The phosphors also showed good thermoluminescence characteristics when they were exposed to γ-rays at a 5 Gy dose at the rate of 0.36 kGyh(-1) . KMgSO4 F:Ce exhibited a single thermoluminescence (TL) peak at around 167 °C and KMgSO4 F:Mn also exhibited a single TL peak at around 177 °C. Possible trapping parameters such as order of kinetics (b), the geometrical factor (μg ), the frequency factor (s) and the activation energy were also evaluated by Chen's half width method. This article discusses fundamental PL and TL characteristics in inorganic fluoride material activated by Ce(3+) and Mn(2+) ions and prepared by a wet chemical method. Copyright © 2014 John Wiley & Sons, Ltd.

  17. Apolipoprotein A-I mimetic peptide 4F blocks sphingomyelinase-induced LDL aggregation.

    PubMed

    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

    2015-06-01

    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. Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.

  18. Investigations of electron attachment to the perfluorocarbon molecules c-C4F8, 2-C4F8, 1,3 C4F6, and c-C5F8

    NASA Astrophysics Data System (ADS)

    Feil, Stefan; Märk, Tilmann D.; Mauracher, Andreas; Scheier, Paul; Mayhew, Chris A.

    2008-11-01

    Non-dissociative and dissociative electron attachment to a series of gas-phase perfluorocarbons (PFCs), namely octafluorocyclobutane, c-C4F8, octafluorobut-2-ene (perfluoro-2-butene), 2-C4F8, hexafluorobuta-1,3-diene (1,3 perfluorobutadiene), 1,3 C4F6, and octafluorocyclopentene (perfluorocyclopentene), c-C5F8, of importance to technological plasmas, have been investigated using two different, but complimentary, instruments available in Innsbruck over the electron energy range 0-20 eV. Anion yields as a function of electron energy have been recorded, with the positions and intensities of the electron attachment resonances being determined. One of these instruments is a double focusing sector field mass spectrometer (VG-ZAB-2SEQ), which has been used for measurements requiring high sensitivity and for obtaining accurate relative anion yields. It has also been used to determine the electron detachment lifetimes of the parent anions under various accelerating voltages, and these results are also presented. The second instrument (CELIA) is a trochoidal electron monochromator coupled to a quadrupole mass filter with a pulse counting system for detecting product anionic species. This provides a much higher energy resolution than the VG-ZAB, which makes it a better instrument to investigate narrow energy resonances close to 0 eV. The results of anion yields, peak positions and the relative intensities presented in this paper are compared with previous data of electron attachment to the above PFCs, including investigations by Professor Eugen Illenberger.

  19. 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

  20. Observation of thermal electron detachment from cyclo-C4F8- in FALP experiments

    NASA Astrophysics Data System (ADS)

    Miller, Thomas M.; Morris, Robert A.; Stevens Miller, Amy E.; Viggiano, A. A.; Paulson, John F.

    1994-08-01

    The methodology for use of a flowing afterglow--Langmuir probe apparatus to measure thermal electron detachment rate coefficients is described. We determined the thermal detachment rate coefficient (1010 ± 300 s-1) for cyclo-C4F8- ions and the rate coefficient (1.6 ± × 10-8 cm3 s-1) for electron attachment of cyclo-C4F8 at 375 K. The sole ionic product of attachment is cyclo-C4F8-. The equilibrium constant for the attachment/detachment reaction yields a free energy for attachment at 375 K of -0.63 ± 0.02 eV, from which we estimate the electron affinity (0 K value) of cyclo-C4F8 to be about 0.63 eV.

  1. Characterization of the active site properties of CYP4F12.

    PubMed

    Eksterowicz, John; Rock, Dan A; Rock, Brooke M; Wienkers, Larry C; Foti, Robert S

    2014-10-01

    Cytochrome P450 4F12 is a drug-metabolizing enzyme that is primarily expressed in the liver, kidney, colon, small intestine, and heart. The properties of CYP4F12 that may impart an increased catalytic selectivity (decreased promiscuity) were explored through in vitro metabolite elucidation, kinetic isotope effect experiments, and computational modeling of the CYP4F12 active site. By using astemizole as a probe substrate for CYP4F12 and CYP3A4, it was observed that although CYP4F12 favored astemizole O-demethylation as the primary route of metabolism, CYP3A4 was capable of metabolizing astemizole at multiple sites on the molecule. Deuteration of astemizole at the site of O-demethylation resulted in an isotope effect of 7.1 as well as an 8.3-fold decrease in the rate of clearance for astemizole by CYP4F12. Conversely, although an isotope effect of 3.8 was observed for the formation of the O-desmethyl metabolite when deuterated astemizole was metabolized by CYP3A4, there was no decrease in the clearance of astemizole. Development of a homology model of CYP4F12 based on the crystal structure of cytochrome P450 BM3 predicted an active site volume for CYP4F12 that was approximately 76% of the active site volume of CYP3A4. As predicted, multiple favorable binding orientations were available for astemizole docked into the active site of CYP3A4, but only a single binding orientation with the site of O-demethylation oriented toward the heme was identified for CYP4F12. Overall, it appears that although CYP4F12 may be capable of binding similar ligands to other cytochrome P450 enzymes such as CYP3A4, the ability to achieve catalytically favorable orientations may be inherently more difficult because of the increased steric constraints of the CYP4F12 active site. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

  2. 4f photoionization and subsequent Auger decay in atomic Pb: Relativistic effects

    SciTech Connect

    Patanen, M.; Kantia, T.; Heinaesmaeki, S.; Aksela, S.; Aksela, H.; Urpelainen, S.

    2011-05-15

    High-resolution 4f photoelectron and subsequent Auger-electron spectra have been measured from free Pb atoms using synchrotron radiation. The fine structure of the spectra has been investigated theoretically by calculating the energies and intensities for 4f photoionization and Auger decay processes using the multiconfigurational Dirac-Fock approach. The role of the relativistic effects in the ground and singly and doubly ionized states has been studied on the basis of computed results and their comparison with experiment.

  3. A Novel Nonsense Mutation of POU4F3 Gene Causes Autosomal Dominant Hearing Loss

    PubMed Central

    Zhang, Chi; Wang, Mingming; Zhang, Fengguo; Zhou, Yicui; Li, Jianfeng; Zheng, Qingyin; Bai, Xiaohui

    2016-01-01

    POU4F3 gene encodes a transcription factor which plays an essential role in the maturation and maintenance of hair cells in cochlea and vestibular system. Several mutations of POU4F3 have been reported to cause autosomal dominant nonsyndromic hearing loss in recent years. In this study, we describe a pathogenic nonsense mutation located in POU4F3 in a four-generation Chinese family. Target region capture sequencing was performed to search for the candidate mutations from 81 genes related to nonsyndromic hearing loss in this family. A novel nonsense mutation of POU4F3, c.337C>T (p. Gln113⁎), was identified in a Chinese family characterized by late-onset progressive nonsyndromic hearing loss. The novel mutation cosegregated with hearing loss in this family and was absent in 200 ethnicity-matched controls. The mutation led to a stop codon and thus a truncated protein with no functional domains remained. Transient transfection and immunofluorescence assay revealed that the subcellular localization of the truncated protein differed markedly from normal protein, which could be the underlying reason for complete loss of its normal function. Here, we report the first nonsense mutation of POU4F3 associated with progressive hearing loss and explored the possible underlying mechanism. Routine examination of POU4F3 is necessary for the genetic diagnosis of hereditary hearing loss in the future. PMID:27999687

  4. CYP4F18-Deficient Neutrophils Exhibit Increased Chemotaxis to Complement Component C5a.

    PubMed

    Vaivoda, Rachel; Vaine, Christine; Boerstler, Cassandra; Galloway, Kristy; Christmas, Peter

    2015-01-01

    CYP4Fs were first identified as enzymes that catalyze hydroxylation of leukotriene B4 (LTB4). CYP4F18 has an unusual expression in neutrophils and was predicted to play a role in regulating LTB4-dependent inflammation. We compared chemotaxis of wild-type and Cyp4f18 knockout neutrophils using an in vitro assay. There was no significant difference in the chemotactic response to LTB4, but the response to complement component C5a increased 1.9-2.25-fold in knockout cells compared to wild-type (P < 0.01). This increase was still observed when neutrophils were treated with inhibitors of eicosanoid synthesis. There were no changes in expression of other CYP4 enzymes in knockout neutrophils that might compensate for loss of CYP4F18 or lead to differences in activity. A mouse model of dextran sodium sulfate colitis was used to investigate the consequences of increased C5a-dependent chemotaxis in vivo, but there was no significant difference in weight loss, disease activity, or colonic tissue myeloperoxidase between wild-type and Cyp4f18 knockout mice. This study demonstrates the limitations of inferring CYP4F function based on an ability to use LTB4 as a substrate, points to expanding roles for CYP4F enzymes in immune regulation, and underscores the in vivo challenges of CYP knockout studies.

  5. CYP4F18-Deficient Neutrophils Exhibit Increased Chemotaxis to Complement Component C5a

    PubMed Central

    Vaivoda, Rachel; Vaine, Christine; Boerstler, Cassandra; Galloway, Kristy; Christmas, Peter

    2015-01-01

    CYP4Fs were first identified as enzymes that catalyze hydroxylation of leukotriene B4 (LTB4). CYP4F18 has an unusual expression in neutrophils and was predicted to play a role in regulating LTB4-dependent inflammation. We compared chemotaxis of wild-type and Cyp4f18 knockout neutrophils using an in vitro assay. There was no significant difference in the chemotactic response to LTB4, but the response to complement component C5a increased 1.9–2.25-fold in knockout cells compared to wild-type (P < 0.01). This increase was still observed when neutrophils were treated with inhibitors of eicosanoid synthesis. There were no changes in expression of other CYP4 enzymes in knockout neutrophils that might compensate for loss of CYP4F18 or lead to differences in activity. A mouse model of dextran sodium sulfate colitis was used to investigate the consequences of increased C5a-dependent chemotaxis in vivo, but there was no significant difference in weight loss, disease activity, or colonic tissue myeloperoxidase between wild-type and Cyp4f18 knockout mice. This study demonstrates the limitations of inferring CYP4F function based on an ability to use LTB4 as a substrate, points to expanding roles for CYP4F enzymes in immune regulation, and underscores the in vivo challenges of CYP knockout studies. PMID:26613087

  6. 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.

  7. 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.

  8. D-4F decreases white matter damage after stroke in mice

    PubMed Central

    Cui, Xu; Chopp, Michael; Zacharek, Alex; Cui, Chengcheng; Yan, Tao; Ning, Ruizhuo; Chen, Jieli

    2015-01-01

    Background and Purpose Stroke induced neuroinflammation and white-matter damage are associated with neurological deficits. Whether D-4F, an apolipoprotein A-I mimetic peptide, treatment of stroke decreases neuroinflammation and white-matter damage and improves functional outcome has not been investigated. Methods Adult male C57BL/6 mice were subjected to permanent middle cerebral artery occlusion (MCAo) and were orally administered saline as a vehicle control and different doses of D-4F (2, 4, 8, 16 or 32mg/kg) starting at 2h after MCAo and daily until sacrifice at 7 days after MCAo. D-4F-treatment did not alter the blood levels of high density lipoprotein, total-cholesterol, triglyceride, blood-brain barrier leakage and infarction volume compared to control group. Results D-4F (16mg/kg) treatment of stroke significantly improved functional outcome, increased the white-matter density and the number of oligodendrocyte-progenitor cells in the ischemic boundary zone of the ipsilateral striatum, and increased myelin basic protein, insulin-like growth factor-1, but decreased inflammatory factor toll-like receptor-4 and tumor necrosis factor alpha expression in the ischemic brain 7 days after MCAo (p<0.05, n=11/group). The neurite/axonal outgrowth in primary cultured neurons was significantly increased when treated with D-4F (100ng/ml) and insulin-like growth factor-1 (100ng/ml) compared with the non-treatment control. Inhibition of IGF1 significantly attenuated D-4F or insulin-like growth factor-1 treatment induced axonal outgrowth. D-4F-treatment did not increase oligodendrocyte-progenitor cell proliferation but decreased oligodendrocyte-progenitor cell death. Conclusions D-4F-treatment initiated 2h after MCAo decreases neuroinflammation and white-matter damage and improves functional outcome after stroke. D-4F-induced increase in insulin-like growth factor-1 may contribute to D-4F-induced neurite/axonal outgrowth after stroke. PMID:26604250

  9. Pseudotetragonal structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50): the first mixed valence cerium fluoride.

    PubMed

    Renaudin, Guillaume; Dieudonné, Belto; Avignant, Daniel; Mapemba, Elise; El-Ghozzi, Malika; Fleutot, Solène; Martinez, Hervé; Cerný, Radovan; Dubois, Marc

    2010-01-18

    The crystal structure of the new Li(5.5)Ce(12)F(50) compound has been fully characterized by single-crystal and synchrotron powder X-ray diffraction. An accurate pseudotetragonal structure was described in the monoclinic P2(1) space group with 68 independent crystallographic sites. The Li(5.5)Ce(12)F(50) composition belongs to the Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) solid solution. Its structure consists of an opened fluorine framework where a channel network allows the intercalation of relatively mobile lithium cations, inducing the formation of the mixed-valence cerium (the intercalation of Li(+) leads to the reduction of a part of Ce(4+) to Ce(3+)). One part of the lithium ions, necessary for the electroneutrality of the tetravalent equivalent cerium fluoride (Li(2)Ce(12)F(50) composition), is in a locked fluorine polyhedron. Only the supplementary x amount of lithium is able to be exchanged in Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50). The structure of Li(2+x)Ce(x)(3+)Ce(12-x)(4+)F(50) is a rearrangement, due to lithium intercalation, of the base CeF(4) structure. Bond valence calculation on Ce sites, Ce coordination polyhedra volumes, and a calculated Ce cationic radius give the indication of a partial long-range ordering of trivalent and tetravalent cerium cations in specific slabs of the structure. (7)Li NMR spectroscopy and XPS analyses have confirmed all of the structure details.

  10. Potyvirus genome-linked protein, VPg, directly affects wheat germ in vitro translation: interactions with translation initiation factors eIF4F and eIFiso4F.

    PubMed

    Khan, Mateen A; Miyoshi, Hiroshi; Gallie, Daniel R; Goss, Dixie J

    2008-01-18

    Potyvirus genome linked protein, VPg, interacts with translation initiation factors eIF4E and eIFiso4E, but its role in protein synthesis has not been elucidated. We show that addition of VPg to wheat germ extract leads to enhancement of uncapped viral mRNA translation and inhibition of capped viral mRNA translation. This provides a significant competitive advantage to the uncapped viral mRNA. To understand the molecular basis of these effects, we have characterized the interaction of VPg with eIF4F, eIFiso4F, and a structured RNA derived from tobacco etch virus (TEV RNA). When VPg formed a complex with eIF4F, the affinity for TEV RNA increased more than 4-fold compared with eIF4F alone (19.4 and 79.0 nm, respectively). The binding affinity of eIF4F to TEV RNA correlates with translation efficiency. VPg enhanced eIFiso4F binding to TEV RNA 1.6-fold (178 nm compared with 108 nm). Kinetic studies of eIF4F and eIFiso4F with VPg show approximately 2.6-fold faster association for eIFiso4F.VPg as compared with eIF4F.VPg. The dissociation rate was approximately 2.9-fold slower for eIFiso4F than eIF4F with VPg. These data demonstrate that eIFiso4F can kinetically compete with eIF4F for VPg binding. The quantitative data presented here suggest a model where eIF4F.VPg interaction enhances cap-independent translation by increasing the affinity of eIF4F for TEV RNA. This is the first evidence of direct participation of VPg in translation initiation.

  11. Electron attachment and detachment and the electron affinity of cyclo-C4F8

    NASA Astrophysics Data System (ADS)

    Miller, Thomas M.; Friedman, Jeffrey F.; Viggiano, A. A.

    2004-04-01

    New measurements have been made of rate constants for electron attachment to c-C4F8 (octafluorocyclobutane) and thermal electron detachment from the parent anion, c-C4F8-, over the temperature range 298-400 K in 133 Pa of He gas in a flowing-afterglow Langmuir-probe apparatus. From these data the electron affinity for c-C4F8 was determined, EA(c-C4F8)=0.63±0.05 eV. The motivation was to resolve a discrepancy between our earlier EA estimate and a higher value (EA=1.05±0.10 eV) reported from a recent experiment of Hiraoka et al. [J. Chem. Phys. 116, 7574 (2002)]. The electron attachment rate constant is 9.3±3.0×10-9 cm3 s-1 at 298 K. The electron detachment rate constant is negligible at room temperature but climbs to 1945±680 s-1 at 400 K. G3(MP2) calculations were carried out for the neutral (D2d, 1A1) and anion (D4h, 2A2u) and yielded EA(c-C4F8-)=0.595 eV. Bond energies were also calculated for loss of F from c-C4F8 and loss of F or F- from c-C4F8-. From these, dissociative electron attachment is found to be endothermic by at least 1.55 eV.

  12. Electron attachment and detachment and the electron affinity of cyclo-C4F8.

    PubMed

    Miller, Thomas M; Friedman, Jeffrey F; Viggiano, A A

    2004-04-15

    New measurements have been made of rate constants for electron attachment to c-C(4)F(8) (octafluorocyclobutane) and thermal electron detachment from the parent anion, c-C(4)F(8) (-), over the temperature range 298-400 K in 133 Pa of He gas in a flowing-afterglow Langmuir-probe apparatus. From these data the electron affinity for c-C(4)F(8) was determined, EA(c-C(4)F(8))=0.63+/-0.05 eV. The motivation was to resolve a discrepancy between our earlier EA estimate and a higher value (EA=1.05+/-0.10 eV) reported from a recent experiment of Hiraoka et al. [J. Chem. Phys. 116, 7574 (2002)]. The electron attachment rate constant is 9.3+/-3.0x10(-9) cm(3) s(-1) at 298 K. The electron detachment rate constant is negligible at room temperature but climbs to 1945+/-680 s(-1) at 400 K. G3(MP2) calculations were carried out for the neutral (D(2d), (1)A(1)) and anion (D(4h), (2)A(2u)) and yielded EA(c-C(4)F(8) (-))=0.595 eV. Bond energies were also calculated for loss of F from c-C(4)F(8) and loss of F or F(-) from c-C(4)F(8) (-). From these, dissociative electron attachment is found to be endothermic by at least 1.55 eV.

  13. XPS Analysis of Nanostructured Materials and Biological Surfaces

    SciTech Connect

    Baer, Donald R.; Engelhard, Mark H.

    2010-05-01

    This paper examines the types of information that XPS can provide about a variety of nano-structured materials. Although it is sometimes not considered a “nano-scale analysis method” XPS can provide a great deal of information about elemental distributions, layer or coating structure and thicknesses, surface functionality, and even particles sizes on the 1-20 nm scale for samples types that may not be readily analyzed by other methods. This information is important for both synthetic nanostructured or nanosized materials and a variety of natural materials with nanostructure. Although the links between nanostructure materials and biological systems may not at first be obvious, many biological molecules and some organisms are the sizes of nanoparticles. The nanostructure of cells and microbes plays a significant role in how they interact with their environment. The interaction of biomolecules with nanoparticles is important for medical and toxicity studies. The interaction of biomolecules is important for sensor function and many nanomaterials are now the active elements in sensors. This paper first discusses how nanostructures influences XPS data as part of understanding how simple models of sample structure and data analysis can be used to extract information about the physical and chemical structure of the materials being analyzed. Equally important, aspects of sample and analysis limitations and challenges associated with understanding nanostructured materials are indicated. Examples of the application of XPS to nanostructured and biological systems and materials are provided.

  14. An Introduction to Surface Analysis by XPS and AES

    NASA Astrophysics Data System (ADS)

    Watts, John F.; Wolstenholme, John

    2003-05-01

    Extensively revised and updated with additional material included in existing chapters and new material on angle resolved XPS, surface engineering and complimentary methods. * Includes an accessible introduction to the key spectroscopic techniques in surface analysis. * Provides descriptions of latest instruments and techniques. * Includes a detailed glossary of key surface analysis terms.

  15. Electron affinity of trans-2-C4F8 from electron attachment-detachment kinetics.

    PubMed

    Van Doren, Jane M; Condon, Laura R; DeSouza-Goding, Antonet; Miller, Thomas M; Bopp, Joseph C; Viggiano, A A

    2010-01-28

    Electron attachment and detachment kinetics of 2-C(4)F(8) were studied over the temperature range 298-487 K with a flowing-afterglow Langmuir-probe apparatus. Only parent anions were formed in the attachment process throughout this temperature range. At the highest temperatures, thermal electron detachment of the parent anions is important. Analysis of the 2-C(4)F(8) gas showed an 82/18 mixture of trans/cis isomers. The kinetic data at the higher temperatures were used to determine the electron affinity EA(trans-2-C(4)F(8)) = 0.79 +/- 0.06 eV after making some reasonable assumptions. The same quantity was calculated using the G3(MP2) compound method, yielding 0.74 eV. The kinetic data were not sufficient to establish a reliable value for EA(cis-2-C(4)F(8)), but G3(MP2) calculations give a value 0.017 eV greater than that for trans-2-C(4)F(8). MP2 and density functional theory were used to study the structural properties of the neutral and anion isomers.

  16. E4F1 controls a transcriptional program essential for pyruvate dehydrogenase activity.

    PubMed

    Lacroix, Matthieu; Rodier, Geneviève; Kirsh, Olivier; Houles, Thibault; Delpech, Hélène; Seyran, Berfin; Gayte, Laurie; Casas, Francois; Pessemesse, Laurence; Heuillet, Maud; Bellvert, Floriant; Portais, Jean-Charles; Berthet, Charlene; Bernex, Florence; Brivet, Michele; Boutron, Audrey; Le Cam, Laurent; Sardet, Claude

    2016-09-27

    The mitochondrial pyruvate dehydrogenase (PDH) complex (PDC) acts as a central metabolic node that mediates pyruvate oxidation and fuels the tricarboxylic acid cycle to meet energy demand. Here, we reveal another level of regulation of the pyruvate oxidation pathway in mammals implicating the E4 transcription factor 1 (E4F1). E4F1 controls a set of four genes [dihydrolipoamide acetlytransferase (Dlat), dihydrolipoyl dehydrogenase (Dld), mitochondrial pyruvate carrier 1 (Mpc1), and solute carrier family 25 member 19 (Slc25a19)] involved in pyruvate oxidation and reported to be individually mutated in human metabolic syndromes. E4F1 dysfunction results in 80% decrease of PDH activity and alterations of pyruvate metabolism. Genetic inactivation of murine E4f1 in striated muscles results in viable animals that show low muscle PDH activity, severe endurance defects, and chronic lactic acidemia, recapitulating some clinical symptoms described in PDC-deficient patients. These phenotypes were attenuated by pharmacological stimulation of PDH or by a ketogenic diet, two treatments used for PDH deficiencies. Taken together, these data identify E4F1 as a master regulator of the PDC.

  17. E4F1 controls a transcriptional program essential for pyruvate dehydrogenase activity

    PubMed Central

    Lacroix, Matthieu; Rodier, Geneviève; Houles, Thibault; Delpech, Hélène; Seyran, Berfin; Gayte, Laurie; Casas, Francois; Pessemesse, Laurence; Heuillet, Maud; Bellvert, Floriant; Portais, Jean-Charles; Berthet, Charlene; Brivet, Michele; Boutron, Audrey; Le Cam, Laurent; Sardet, Claude

    2016-01-01

    The mitochondrial pyruvate dehydrogenase (PDH) complex (PDC) acts as a central metabolic node that mediates pyruvate oxidation and fuels the tricarboxylic acid cycle to meet energy demand. Here, we reveal another level of regulation of the pyruvate oxidation pathway in mammals implicating the E4 transcription factor 1 (E4F1). E4F1 controls a set of four genes [dihydrolipoamide acetlytransferase (Dlat), dihydrolipoyl dehydrogenase (Dld), mitochondrial pyruvate carrier 1 (Mpc1), and solute carrier family 25 member 19 (Slc25a19)] involved in pyruvate oxidation and reported to be individually mutated in human metabolic syndromes. E4F1 dysfunction results in 80% decrease of PDH activity and alterations of pyruvate metabolism. Genetic inactivation of murine E4f1 in striated muscles results in viable animals that show low muscle PDH activity, severe endurance defects, and chronic lactic acidemia, recapitulating some clinical symptoms described in PDC-deficient patients. These phenotypes were attenuated by pharmacological stimulation of PDH or by a ketogenic diet, two treatments used for PDH deficiencies. Taken together, these data identify E4F1 as a master regulator of the PDC. PMID:27621446

  18. High-resolution XPS spectromicroscopy study of micro-patterned gold-tin surfaces

    NASA Astrophysics Data System (ADS)

    Renault, O.; Garnier, A.; Morin, J.; Gambacorti, N.; Bertin, F.

    2012-10-01

    We report on high-resolution chemical state mapping performed with a laboratory, spectroscopic X-ray photoelectron emission microscope (XPEEM) on electro-deposited gold-tin patterns (100 μm × 20 μm) for packaging applications of micro-systems. The analysis conditions were selected to achieve a lateral resolution below 1 μm and an energy resolution of 0.8 eV for Au4f7/2 and Sn3d5/2 for images acquired over 5 min. The chemical state maps reveal the non-uniformity of the gold/tin chemistry over regions of typical width of less than 10 μm. More precisely, the coexistence of Au and AuSn4 states, and the heterogeneity of Sn oxidation were shown. The results evidence the role of the partial delamination of the photo-resist during the electro-deposition of tin due to degraded adhesion properties on gold. These conclusions are drawn from direct inspection of the raw image data sets, and are supported by statistical treatments using Principal Component Analysis (PCA). This is a clear example of the interest in using high resolution XPS imaging by XPEEM at a practical level in applied surface science, and its complementarity to other surface imaging techniques.

  19. KVPO4F and KVOPO4 toward 4 volt-class potassium-ion batteries.

    PubMed

    Chihara, Kuniko; Katogi, Akihiro; Kubota, Kei; Komaba, Shinichi

    2017-05-04

    Structurally identical KVPO4F and KVOPO4 are evaluated as positive electrode materials for non-aqueous potassium-ion batteries. KVPO4F and KVOPO4 show highly reversible potassium extraction/insertion with discharge capacities of ca. 92 mA h g(-1) and ca. 84 mA h g(-1), respectively, and their average discharge voltage reaches above 4.0 V with 1 M KPF6 EC/PC electrolyte at 2.0-5.0 V. Despite the extraction of large potassium-ions, their lattice volume shrinkages after charging to 5.0 V are 5.8% for KVPO4F and 3.3% for KVOPO4, leading to stable cycle performance. This is the first report to confirm the charge/discharge behaviours of vanadium phosphate electrodes in 4 V-class K cells.

  20. SF6 and C4F8 global kinetic models coupled to sheath models

    NASA Astrophysics Data System (ADS)

    Haidar, Yehya; Pateau, Amand; Rhallabi, Ahmed; Fernandez, Marie Claude; Mokrani, Arezki; Taher, Fadia; Roqueta, Fabrice; Boufnichel, Mohamed

    2014-12-01

    Global kinetic models combined with Monte Carlo sheath models are developed for SF6 and C4F8 plasma discharges for silicon etching under the Bosch process. In SF6 plasma, the dominant positive ions are SF_5+ , SF_4+ , SF_3+ and F+ while in C4F8 the dominant positive ions are CF_3+ and C_2F_3+ . The simulation results show that the electrical parameters, such as the electron density and electron temperature, clearly affect the sheath dynamics and consequently the ion energy distribution function evolutions. In this context, we showed the effects of the operating conditions, such as the pressure and the radiofrequency power, on the electron density and electron temperature evolutions as well as the reactive particle fluxes (neutral and positive ions) involved in the plasma surface interactions for etching/deposition under the Bosch process. Ion energy distribution functions obtained from SF6 and C4F8 plasmas are compared with each other as regards the electrical properties of their associated plasmas. The simulation results show that the bimodal peaks of ion energy distribution functions are wider for SF6 plasma than for C4F8 plasma due to the high sheath thickness of SF6 compared to that of C4F8. This is explained by the low electron density due to the high electronegativity of SF6 in comparison to that of C4F8. The simulations also reveal that the bimodal peak of the ion energy distribution function is wider when the ion mass is low.

  1. Hyperfine structure in the configuration 4 f 136 s7 s of Tm I

    NASA Astrophysics Data System (ADS)

    Kronfeldt, H.-D.; Kröger, S.

    1995-12-01

    Doppler-free saturation absorption spectroscopy was applied on an atomic thulium vapour in a see-through hollow cathode for the determination of precise values for the magnetic dipole hyperfine structure constants A of 6 levels of the configuration 4 f 13 6 s7 s. A parametric analysis of the hyperfine structure has been performed, using wave-functions from a fine structure calculation, which leads to one-electron hyperfine structure parameters a {4/f 01}=-500(6) MHz, a {6/s 10}=-5058(47) MHz, and a {7/s 10}=-1012 MHz.

  2. Structure of Some 4f Rare Earth Liquid Metals — A Charged Hard Sphere Approach

    NASA Astrophysics Data System (ADS)

    P. B., Thakor; P. N., Gajjar; A. R., Jani

    2006-08-01

    A well-established pseodopotential is used to study the structure of some 4f rare earth liquid metals (Ce, Pr, Eu, Gd, Tb, and Yb). The structure factor S(q), pair distribution function g(r), interatomic distance r1, and coordination number n1 are calculated using Charged Hard Sphere (CHS) reference system. To introduce the exchange and correlation effects, the local field correction due to Sarkar et al. (S) is applied. The present investigation is successful in generating the structural information of Ce, Pr, Eu, Gd, Tb, and Yb 4f rare earth liquid metals.

  3. 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.

  4. 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

  5. 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. © 2016 The Authors.

  6. An XPS study of the iron surface promoted by potassium

    SciTech Connect

    Perov, V.M.

    1995-03-01

    The surface composition of a model iron-potassium catalytic system in oxidized and reduced states is studied by XPS. It is found that the potassium-to-oxygen atomic ratio for the surface of reduced samples is one. The distributions of elements in subsurface layers of the reduced system are determined by varying the detection angle of emitted electrons and by ion sputtering of the surface. It is shown that potassium and oxygen form a monolayer on the surface of iron crystallites.

  7. Thermoresponsive gold nanoshell@mesoporous silica nano-assemblies: an XPS/NMR survey.

    PubMed

    Soulé, S; Allouche, J; Dupin, J-C; Courrèges, C; Plantier, F; Ojo, W-S; Coppel, Y; Nayral, C; Delpech, F; Martinez, H

    2015-11-21

    This work provides a detailed study on the physico-chemical characterization of a mechanized silver-gold alloy@mesoporous silica shell/pseudorotaxane nano-assembly using two main complementary techniques: XPS and NMR (liquid- and solid-state). The pseudorotaxane nanovalve is composed of a stalk (N-(6-aminohexyl)-aminomethyltriethoxysilane)/macrocycle (cucurbit[6]uril (CB6)) complex anchored to the silica shell leading to a silica/nanovalve hybrid organic-inorganic interface that has been fully characterized. The stalk introduction in the silica network was clearly demonstrated by XPS measurements, with the Si 2p peak shifting to lower energy after grafting, and through the analysis of the C 1s and N 1s core peaks, which indicated the presence of CB6 on the nanoparticle surface. For the first time, the complex formation on nanoparticles was proved by high speed (1)H MAS NMR experiments. However, these solid state NMR analyses have shown that the majority of the stalk does not interact with the CB6 macrocycle when formulated in powder after removing the solvent. This can be related to the large number of possible organizations and interactions between the stalk, the CB6 and the silica surface. These results highlight the importance of using a combination of adapted and complementary highly sensitive surface and volume characterization techniques to design tailor-made hybrid hierarchical structured nano-assemblies with controlled and efficient properties for potential biological purposes.

  8. 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 under...

  9. 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...

  10. 48 CFR 47.303-4 - F.o.b. origin, freight prepaid.

    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. origin, freight... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term. F.o.b. origin, freight prepaid means— (1) Free of expense...

  11. 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... CONTRACT MANAGEMENT TRANSPORTATION Transportation in Supply Contracts 47.303-4 F.o.b. origin, freight prepaid. (a) Explanation of delivery term. F.o.b. origin, freight prepaid means— (1) Free of expense...

  12. 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...

  13. Reversing chemoresistance by small molecule inhibition of the translation initiation complex eIF4F

    PubMed Central

    Cencic, Regina; Hall, David R.; Robert, Francis; Du, Yuhong; Min, Jaeki; Li, Lian; Qui, Min; Lewis, Iestyn; Kurtkaya, Serdar; Dingledine, Ray; Fu, Haian; Kozakov, Dima; Vajda, Sandor; Pelletier, Jerry

    2011-01-01

    Deregulation of cap-dependent translation is associated with cancer initiation and progression. The rate-limiting step of protein synthesis is the loading of ribosomes onto mRNA templates stimulated by the heterotrimeric complex, eukaryotic initiation factor (eIF)4F. This step represents an attractive target for anticancer drug discovery because it resides at the nexus of the TOR signaling pathway. We have undertaken an ultra-high-throughput screen to identify inhibitors that prevent assembly of the eIF4F complex. One of the identified compounds blocks interaction between two subunits of eIF4F. As a consequence, cap-dependent translation is inhibited. This compound can reverse tumor chemoresistance in a genetically engineered lymphoma mouse model by sensitizing cells to the proapoptotic action of DNA damage. Molecular modeling experiments provide insight into the mechanism of action of this small molecule inhibitor. Our experiments validate targeting the eIF4F complex as a strategy for cancer therapy to modulate chemosensitivity. PMID:21191102

  14. Proposed Plan for the Burma Road Rubble Pit (231-4F)

    SciTech Connect

    Palmer, E.

    1995-11-01

    The purpose of this proposed plan is to describe the preferred alternative for addressing the Burma Road Rubble Pit (BRRP) source unit soils (231-4F) located at the SRS in Aiken, South Carolina and to provide an opportunity for public input into the remedial action selection process.

  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 under...

  16. 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 section 203(c). 55.8 Section 55.8 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) IMPLEMENTATION OF THE PROVISIONS OF THE VOTING RIGHTS ACT REGARDING LANGUAGE MINORITY GROUPS Nature of Coverage § 55...

  17. 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.

  18. 28 CFR 55.8 - Relationship between section 4(f)(4) and section 203(c).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the 1975 Amendments to the Act. (c) Although the coverage formulas applicable to section 4(f)(4) and section 203(c) are different, a political subdivision may be included within both of the coverage formulas. Under these circumstances, a judgment terminating coverage of the jurisdiction under one provision would...

  19. 32 CFR 1630.44 - Class 4-F: Registrant not acceptable for military service.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... military service. 1630.44 Section 1630.44 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM CLASSIFICATION RULES § 1630.44 Class 4-F: Registrant not acceptable for military... accomplished and such registrant continues to be found not acceptable for military service. ...

  20. 32 CFR 1630.44 - Class 4-F: Registrant not acceptable for military service.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... military service. 1630.44 Section 1630.44 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM CLASSIFICATION RULES § 1630.44 Class 4-F: Registrant not acceptable for military... accomplished and such registrant continues to be found not acceptable for military service. ...

  1. Bulk plasma fragmentation in a C4F8 inductively coupled plasma: A hybrid modeling study

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    A hybrid model is used to investigate the fragmentation of C4F8 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. CxFy (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 C4F8 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 C4F8 reaction set used in the model. The C4F8 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.

  2. 32 CFR 1630.44 - Class 4-F: Registrant not acceptable for military service.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... military service. 1630.44 Section 1630.44 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM CLASSIFICATION RULES § 1630.44 Class 4-F: Registrant not acceptable for military... accomplished and such registrant continues to be found not acceptable for military service....

  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 investigations of tribofilms formed on CrN coatings

    NASA Astrophysics Data System (ADS)

    Mandrino, Djordje; Podgornik, Bojan

    2017-02-01

    Action of lubrication additives in the case of uncoated steel surfaces, including the type and mechanism of tribofilm formation is well known and understood. However, contact type of tribofilms which might form under the tribological contact between CrN coated surfaces, remains more or less unexplored. The aim of this investigation was to study the type of tribofilms formed on the CrN coated steel samples subjected to lubricated reciprocating sliding contact under different contact conditions Contact surface and tribofilms formed were studied by X-ray Photoelectron Spectroscopy (XPS). Sample surfaces were first imaged by Scanning Electron Microscopy (SEM) to determine areas of tribofilm formation as well as areas not affected by tribological contact. In these areas survey and high resolution (HR) XPS measurements were performed to obtain information about surface chemistry and oxidation states of the constituent elements. It was found that differences between different samples, observed by the XPS measurements, may reflect differences in chemistry of tribofilms formed under different contact conditions.

  5. Rapamycin-sensitive induction of eukaryotic initiation factor 4F in regenerating mouse liver.

    PubMed

    Goggin, Melissa M; Nelsen, Christopher J; Kimball, Scot R; Jefferson, Leonard S; Morley, Simon J; Albrecht, Jeffrey H

    2004-09-01

    Following acute injuries that diminish functional liver mass, the remaining hepatocytes substantially increase overall protein synthesis to meet increased metabolic demands and to allow for compensatory liver growth. Previous studies have not clearly defined the mechanisms that promote protein synthesis in the regenerating liver. In the current study, we examined the regulation of key proteins involved in translation initiation following 70% partial hepatectomy (PH) in mice. PH promoted the assembly of eukaryotic initiation factor (eIF) 4F complexes consisting of eIF4E, eIF4G, eIF4A1, and poly-A binding protein. eIF4F complex formation after PH occurred without detectable changes in eIF4E-binding protein 1 (4E-BP1) phosphorylation or its binding eIF4E. The amount of serine 1108-phosphorylated eIF4G (but not Ser209-phosphorylated eIF4E) was induced following PH. These effects were antagonized by treatment with rapamycin, indicating that target of rapamycin (TOR) activity is required for eIF4F assembly in the regenerating liver. Rapamycin inhibited the induction of cyclin D1, a known eIF4F-sensitive gene, at the level of protein expression but not messenger RNA (mRNA) expression. In conclusion, increased translation initiation mediated by the mRNA cap-binding complex eIF4F contributes to the induction of protein synthesis during compensatory liver growth. Further study of factors that regulate translation initiation may provide insight into mechanisms that govern metabolic homeostasis and regeneration in response to liver injury.

  6. Core-level spectra and binding energies of transition metal nitrides by non-destructive x-ray photoelectron spectroscopy through capping layers

    NASA Astrophysics Data System (ADS)

    Greczynski, G.; Primetzhofer, D.; Lu, J.; Hultman, L.

    2017-02-01

    We present the first measurements of x-ray photoelectron spectroscopy (XPS) core level binding energies (BE:s) for the widely-applicable group IVb-VIb polycrystalline transition metal nitrides (TMN's) TiN, VN, CrN, ZrN, NbN, MoN, HfN, TaN, and WN as well as AlN and SiN, which are common components in the TMN-based alloy systems. Nitride thin film samples were grown at 400 °C by reactive dc magnetron sputtering from elemental targets in Ar/N2 atmosphere. For XPS measurements, layers are either (i) Ar+ ion-etched to remove surface oxides resulting from the air exposure during sample transfer from the growth chamber into the XPS system, or (ii) in situ capped with a few nm thick Cr or W overlayers in the deposition system prior to air-exposure and loading into the XPS instrument. Film elemental composition and phase content is thoroughly characterized with time-of-flight elastic recoil detection analysis (ToF-E ERDA), Rutherford backscattering spectrometry (RBS), and x-ray diffraction. High energy resolution core level XPS spectra acquired with monochromatic Al Kα radiation on the ISO-calibrated instrument reveal that even mild etching conditions result in the formation of a nitrogen-deficient surface layer that substantially affects the extracted binding energy values. These spectra-modifying effects of Ar+ ion bombardment increase with increasing the metal atom mass due to an increasing nitrogen-to-metal sputter yield ratio. The superior quality of the XPS spectra obtained in a non-destructive way from capped TMN films is evident from that numerous metal peaks, including Ti 2p, V 2p, Zr 3d, and Hf 4f, exhibit pronounced satellite features, in agreement with previously published spectra from layers grown and analyzed in situ. In addition, the N/metal concentration ratios are found to be 25-90% higher than those obtained from the corresponding ion-etched surfaces, and in most cases agree very well with the RBS and ToF-E ERDA values. The N 1 s BE:s extracted from

  7. 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

  8. Threshold kinetic processes for t-C4F9I. [for solar-pumped lasers

    NASA Technical Reports Server (NTRS)

    Lee, J. H.; Wilson, J. W.; Humes, D. H.; Weaver, W. R.; Enderson, T.; Tabibi, B. M.

    1985-01-01

    To determine the relative threshold of the lasant gas t-C4F9I in comparison to n-C3F7I, the pump energy to reach threshold for photodissociation iodine lasing is measured in a common aparatus. The comparison is made for the threshold energies in the iodide pressure range up to 50 Torr when 64-J electric input into a flashlamp is used for pumping. It is shown from the results that qualitative differences between the thresholds of the two gases result from the degree to which steady state is achieved by the time threshold is reached. The estimated recombination rate for t-C4F9I is found to be much larger than the value given by Ershov et al (1978).

  9. Tetradecanuclearity in 3d-4f chemistry: relaxation and magnetocaloric effects in [NiLn] species.

    PubMed

    Canaj, Angelos B; Kalofolias, Dimitris A; Siczek, Milosz; Lis, Tadeusz; McNab, Robbie; Lorusso, Giulia; Inglis, Ross; Evangelisti, Marco; Milios, Constantinos J

    2017-03-14

    The employment of 2-amino-isobutyric acid, Haib, and 2-hydroxy-1-naphthaldehyde, Hnaphth, in Ni(II)/Ln(III) chemistry has led to the isolation and characterization of two new isostructural 3d-4f tetradecanuclear [NiLn] clusters (Ln = Gd(III), Dy(III)), with the Dy analogue displaying temperature and frequency dependent out-of-phase signals, and the Gd analogue showing interesting magnetocaloric properties.

  10. Contribution of Eu 4f states to the magnetic anisotropy of EuO

    SciTech Connect

    Arenholz, E.; Schmehl, A.; Schlom, D.G.; van der Laan, G.

    2008-09-11

    Anisotropic x-ray magnetic linear dichroism (AXMLD) provides a novel element-, site-, shell-, and symmetry-selective techniques to study the magnetic anisotropy induced by a crystalline electric field. The weak Eu2+ M4,5 AXMLD observed in EuO(001) indicates that the Eu 4f states are not rotationally invariant and hence contribute weakly to the magnetic anisotropy of EuO. The results are contrasted with those obtained for 3d transition metal oxides.

  11. Phase-retrieval algorithms applied in a 4-f system for optical image encryption: a comparison

    NASA Astrophysics Data System (ADS)

    Situ, Guohai; Zhang, Jingjuan

    2005-01-01

    Phase retrieval algorithms based on 4-f system for optical image encryption are compared in respect of the image retrieval quality and the convergence. Simulation results show that enlarging the searching space can decrypt the image with extremely high quality, while employing the searching strategy of modifying both the phase-distributions in the input and the frequency planes can result in much faster convergence for the algorithm.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  13. 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.

  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. Race-specific influence of CYP4F2 on dose and risk of hemorrhage among warfarin users

    PubMed Central

    Shendre, Aditi; Brown, Todd M.; Liu, Nianjun; Hill, Charles E; Beasley, T. Mark; Nickerson, Deborah. A.; Limdi, Nita. A.

    2016-01-01

    Summary Objective The p.V433M in cytochrome P450 4F2 (rs2108622, CYP4F2*3) is associated with higher warfarin dose and lower risk of hemorrhage among European Americans. Herein, we evaluate the influence of CYP4F2*3 on warfarin dose, time to target INR and stable dose, proportion of time spent in target range (PTTR), as well as the risk of overanticoagulation and hemorrhage among European and African Americans. Design CYP4F2*3 was genotyped in 1238 patients initiated on warfarin in a prospective inception cohort. Multivariable linear regression was used to assess warfarin dose and PTTR; proportional hazards analysis was performed to evaluate time to target INR and stable dose, overanticoagulation, and hemorrhage. Setting Two outpatient anticoagulation clinics Participants 1238 anticoagulated patients Outcomes Warfarin dose (mg/day), time to target INR and stable dose, PTTR, over anticoagulation (INR>4), and major hemorrhage. Results Minor allele frequency for the CYP4F2*3 variant was 30.3% among European Americans and 8.4% among African Americans. CYP4F2*3 was associated with higher dose among European Americans but not African Americans. Compared to CYP4F2*1/*1, *1/*3 was associated with a statistically nonsignificant increase in dose (4.5%, p=0.22) and *3/*3 was associated with a statistically significant increase in dose (13.2% , p=0.02). CYP4F2 genotype did not influence time to target INR, time to stable dose, or PTTR in either race group. CYP4F2*3/*3 was associated with a 31% lower risk of over anticoagulation (p=0.06). Incidence of hemorrhage was lower among participants with CYP4F2 *3/*3 compared to *1/*3 or *1/*1 (IRR=0.45; 95% CI: 0.14 – 1.11; p=0.09). After controlling for covariates, the CYP4F2 *3/*3 was associated with a 52% lower risk of hemorrhage although this was not statistically significant (p=0.24). Conclusion Possession of CYP4F2*3 variant influences warfarin dose among European Americans but not African Americans. The CYP4F2-dose, CYP4F2

  16. Effect of Sr doping in layered Eu3Bi2S4F4 superconductor

    NASA Astrophysics Data System (ADS)

    Zhang, Pan; Zhai, Hui-Fei; Wang, Zhen; Chen, Jian; Feng, Chun-Mu; Cao, Guang-Han; Xu, Zhu-An

    2017-01-01

    We report the effect of Sr-doping in the BiS2-based superconductor {{Eu}}3-xSr x Bi2S4F4. Eu3Bi2S4F4 is a self-doped compound with a mixed Eu valence state. By the partial substitution of Sr for Eu, T c gradually decreases and superconductivity disappears above 0.3 K when x\\gt 1.0. Magnetic-susceptibility and specific-heat measurements reveal that Sr substitution leads to a decrease in both Eu2+ and Eu3+ populations. The decreased Eu3+ population, and the corresponding lower charge carrier density, may be the main origin for the suppression of superconductivity. In addition, we find a significant increase in the Sommerfeld coefficient {γ }0 upon Sr doping, which may be due to the Kondo effect between the magnetic moments (associated to Eu2+ ions) and the conducting electrons. This work implies that the Kondo effect could compete with superconductivity in Eu3Bi2S4F4.

  17. The transcription factor E4F1 coordinates CHK1-dependent checkpoint and mitochondrial functions.

    PubMed

    Rodier, Geneviève; Kirsh, Olivier; Baraibar, Martín; Houlès, Thibault; Lacroix, Matthieu; Delpech, Hélène; Hatchi, Elodie; Arnould, Stéphanie; Severac, Dany; Dubois, Emeric; Caramel, Julie; Julien, Eric; Friguet, Bertrand; Le Cam, Laurent; Sardet, Claude

    2015-04-14

    Recent data support the notion that a group of key transcriptional regulators involved in tumorigenesis, including MYC, p53, E2F1, and BMI1, share an intriguing capacity to simultaneously regulate metabolism and cell cycle. Here, we show that another factor, the multifunctional protein E4F1, directly controls genes involved in mitochondria functions and cell-cycle checkpoints, including Chek1, a major component of the DNA damage response. Coordination of these cellular functions by E4F1 appears essential for the survival of p53-deficient transformed cells. Acute inactivation of E4F1 in these cells results in CHK1-dependent checkpoint deficiency and multiple mitochondrial dysfunctions that lead to increased ROS production, energy stress, and inhibition of de novo pyrimidine synthesis. This deadly cocktail leads to the accumulation of uncompensated oxidative damage to proteins and extensive DNA damage, ending in cell death. This supports the rationale of therapeutic strategies simultaneously targeting mitochondria and CHK1 for selective killing of p53-deficient cancer cells.

  18. Superhydrophobic treatment using atmospheric-pressure He/C4F8 plasma for buoyancy improvement

    NASA Astrophysics Data System (ADS)

    Noh, Sooryun; Moon, A.-Young; Moon, Se Youn

    2015-04-01

    A superhydrophobic miniature boat was fabricated with aluminum alloy plates treated with atmospheric-pressure helium (He)/octafluorocyclobutane (C4F8) plasma using 13.56 MHz rf power. When only 0.13% C4F8 was added to He gas, the contact angle of the surface increased to 140° and the surface showed superhydrophobic properties. On the basis of chemical and morphological analyses, fluorinated functional groups (CF, CF2, and CF3) and nano-/micro-sized particles were detected on the Al surface. These features brought about superhydrophobicity similar to the lotus effect. While the miniature boat, assembled with plasma-treated plates, was immersed in water, a layer of air (i.e., a plastron) surrounded the superhydrophobic surfaces. This effect contributed to the development of a 4.7% increase in buoyancy. In addition, the superhydrophobic properties lasted for two months under the submerged condition. These results demonstrate that treatment with atmospheric-pressure He/C4F8 plasma is a promising method of improving the load capacity and antifouling properties, and reducing the friction of marine ships through a fast and low-cost superhydrophobic treatment process.

  19. 3d/4f Coordination Clusters as Cooperative Catalysts for Highly Diastereoselective Michael Addition Reactions.

    PubMed

    Griffiths, Kieran; Tsipis, Athanassios C; Kumar, Prashant; Townrow, Oliver P E; Abdul-Sada, Alaa; Akien, Geoffrey R; Baldansuren, Amgalanbaatar; Spivey, Alan C; Kostakis, George E

    2017-08-21

    Michael addition (MA) is one of the most well studied chemical transformation in synthetic chemistry. Here, we report the synthesis and crystal structures of a library of 3d/4f coordination clusters (CCs) formulated as [Zn(II)2Y(III)2L4(solv)X(Z)Y] and study their catalytic properties toward the MA of nitrostyrenes with barbituric acid derivatives. Each CC presents two borderline hard/soft Lewis acidic Zn(II) centers and two hard Lewis acidic Y(III) centers in a defect dicubane topology that brings the two different metals into a proximity of ∼3.3 Å. Density functional theory computational studies suggest that these tetrametallic CCs dissociate in solution to give two catalytically active dimers, each containing one 3d and one 4f metal that act cooperatively. The mechanism of catalysis has been corroborated via NMR, electron paramagnetic resonance, and UV-vis. The present work demonstrates for the first time the successful use of 3d/4f CCs as efficient and high diastereoselective catalysts in MA reactions.

  20. Copper Bronze Powder Surface Studied by XPS and HR SEM

    NASA Astrophysics Data System (ADS)

    Shvab, R.; Hryha, E.; Tahir, A. M.; Nyborg, L.

    2016-10-01

    The state of the powder surface represents one of the main interests in the whole cycle of components' production using powder metallurgy (PM) route. Large specific surface area of the powder in combination with often alloying with oxygen sensitive elements results in oxidation of the powder surface in most of the cases. The information about surface chemistry of the powder is of vital importance for further consolidation and sintering steps. Surface sensitive analytical techniques - X-ray photoelectron spectroscopy (XPS) and high-resolution scanning electron microscopy combined with energy dispersive X-ray analysis (HR SEM+EDX) were used for surface chemical analysis of the 60Cu-40Sn bronze powder. Determination of the compositional profiles and estimation of the surface oxide layer thickness was done by altering of ion etching and XPS analysis. The results showed tin oxide enrichment and presence of copper hydroxide on the surface of the powder particles. The impurities of P, Zn and Ca were also detected on the top surface of the powder in trace amounts.

  1. Quantitative XPS analysis of silica-supported Cu Co oxides

    NASA Astrophysics Data System (ADS)

    Cesar, Deborah V.; Peréz, Carlos A.; Schmal, Martin; Salim, Vera Maria M.

    2000-04-01

    Copper-cobalt oxides with Cu/Co=5:5, 15:15 and 35:35 bulk ratio have been prepared by deposition-precipitation method at constant pH from copper and cobalt nitrate solutions. Different oxides were obtained by decomposition of the precursors at 673 K for 7 h in air and analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD data showed the formation of different oxide phases; for the bulk atomic ratio of 15Cu:15Co, a phase containing Cu and Co with spinel-like structure was observed, while the other bimetallic oxides presented CuO and Co 3O 4 as distinct phases. The XPS qualitative analysis has shown that all samples exhibited Cu 2+ and Co 3+ species at the surface. The Cu-Co spinel presented a displacement in Cu 2p binding energy value. A mathematical model was proposed from relative intensity ratios, which allowed the determination of the oxide particle thickness and the fraction of coverage at the support. This model described accurately the system and showed that cobalt improved the copper dispersion.

  2. 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.

  3. Potential for carbon adsorption on concrete: surface XPS analyses.

    PubMed

    Haselbach, Liv M; Ma, Shuguo

    2008-07-15

    The concrete industry is a contributor to the global carbon cycle particularly with respect to the contribution of carbon dioxide in the manufacturing of cement (calcination). The reverse reaction of carbonation is known to occur in concrete, but is usually limited to exterior surfaces exposed to carbon dioxide and humidity in the air. As alternate concrete uses expand which have more surface area, such as crushed concrete for recycling, it is important to understand surface adsorption of carbon dioxide and the positive impacts it might have on the carbon cycle. X-ray photoelectron spectroscopy (XPS) is used in this study to evaluate carbon species on hydrated cement mortar surfaces. Initial estimates for carbon absorption in concrete using othertechniques predictthe potential for carbonate species to be a fraction of the calcination stoichiometric equivalent The XPS results indicate that there is a rapid and substantial uptake of carbon dioxide on the surfaces of these mortars, sometimes exceeding the calcination stoichiometric equivalents, indicative of carbon dioxide surface complexation species. On pure calcite, the excess is on the order of 30%. This accelerated carbon dioxide surface adsorption phenomenon may be importantfor determining novel and effective carbon sequestration processes using recycled concrete.

  4. 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

  5. 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

  6. Requirement of the eukaryotic translation initiation factor 4F complex in hepatitis E virus replication.

    PubMed

    Zhou, Xinying; Xu, Lei; Wang, Yijin; Wang, Wenshi; Sprengers, Dave; Metselaar, Herold J; Peppelenbosch, Maikel P; Pan, Qiuwei

    2015-12-01

    Hepatitis E virus (HEV) infection, one of the foremost causes of acute hepatitis, is becoming a health problem of increasing magnitude. As other viruses, HEV exploits elements from host cell biochemistry, but we understand little as to which components of the human hepatocellular machinery are perverted for HEV multiplication. It is, however, known that the eukaryotic translation initiation factors 4F (eIF4F) complex, the key regulator of the mRNA-ribosome recruitment phase of translation initiation, serves as an important component for the translation and replication of many viruses. Here we aim to investigate the role of three subunits of the eIF4F complex: eukaryotic translation initiation factor 4A (eIF4A), eukaryotic translation initiation factor 4G (eIF4G) and eukaryotic translation initiation factor 4E (eIF4E) in HEV replication. We found that efficient replication of HEV requires eIF4A, eIF4G and eIF4E. Consistently, the negative regulatory factors of this complex: programmed cell death 4 (PDCD4) and eIF4E-binding protein 1 (4E-BP1) exert anti-HEV activities, which further illustrates the requirement for eIF4A and eIF4E in supporting HEV replication. Notably, phosphorylation of eIF4E induced by MNK1/2 activation is not involved in HEV replication. Although ribavirin and interferon-α (IFN-α), the most often-used off-label drugs for treating hepatitis E, interact with this complex, their antiviral activities are independent of eIF4E. In contrast, eIF4E silencing provokes enhanced anti-HEV activity of these compounds. Thus, HEV replication requires eIF4F complex and targeting essential elements of this complex provides important clues for the development of novel antiviral therapy against HEV. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. 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.

  8. 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.

  9. 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.

  10. Rare Earth 4f Hybridization with the GaN Valence Band

    DTIC Science & Technology

    2012-01-01

    DOS of Ga17GdN18. and Auger-like electrons emitted in a super Coster– Kronig process [52] 4d104fN + hν → [4d94fN+1]∗ → 4d104fN−1 + e−, (2) where...similar, albeit not identical, response for GaN:Er compared to GaN:Gd at the photon energy characteristic for the Er 4d → 4f super Coster– Kronig resonance

  11. Crater nanochannels of anodic aluminum oxide fabricated in NH4F electrolyte

    NASA Astrophysics Data System (ADS)

    Yu, Mengshi; Cui, Huimin; Zhang, Shaoyu; Zhao, Siwei; Ai, Fuping; Zhu, Xufei

    2017-08-01

    In this work, porous anodic aluminum oxide with crater nanochannels is discovered for the first time while Al is anodized in NH4F electrolyte at high voltages. The unique structure of crater nanochannels is distinctly different from that of general porous anodic aluminum oxide (AAO) and anodic TiO2 nanotubes. A central channel appears and a circle of nanopores surround the channel while there is only one kind of pore in typical AAO and anodic TiO2 nanotubes. This finding may significantly facilitate the fabrication of special structures in AAO and anodic TiO2 nanotubes.

  12. Cerebrovascular disease: evaluation with transbrachial intraarterial digital subtraction angiography using a 4-F catheter.

    PubMed

    Hicks, M E; Kreipke, D L; Becker, G J; Edwards, M K; Holden, R W; Jackson, V P; Bendick, P J; Kuehn, D S

    1986-11-01

    Three hundred sixty-one patients underwent intraarterial digital subtraction angiography for definite or probable occlusive vascular disease of the carotid arteries. Examinations were performed with 65-cm-long, 4-F aortic catheters. A transbrachial approach was used. Images were good or excellent in nearly all cases. No postprocedural neurologic deficits or hematomas occurred. Permanent pulse deficit occurred in two patients, and temporary deficit occurred in three patients, an improvement over the frequency found in previous transbrachial series using 6-8-F catheters. While these results establish the efficacy of this technique, they also indicate a possible greater relative safety in men than in women.

  13. 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)

  14. 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.

  15. Surface Propensity of Atmospherically Relevant Amino Acids Studied by XPS.

    PubMed

    Mocellin, Alexandra; Gomes, Anderson Herbert de Abreu; Araújo, Oscar Cardoso; de Brito, Arnaldo Naves; Bjorneholm, Olle

    2017-03-30

    Amino acids constitute an important fraction of the water-soluble organic nitrogen (WSON) compounds in aerosols and are involved in many processes in the atmosphere. In this work, we applied XPS to study aqueous solutions of four amino acids: glycine, alanine, valine and methionine, in their zwitterionic forms. We found that amino acids with hydrophilic side chains and smaller size, GLY and ALA, tend to stay in the bulk of the liquid, while the hydrophobic and bigger amino acids, VAL and MET, are found to concentrate more on the surface. We found experimental evidences that the amino acids have preferential orientation relative to the surface, with the hydrophobic side chain being closer to the surface than the hydrophilic carboxylate group. The observed amino acid surface propensity has implications in atmospheric science as the surface interaction play a central role in cloud droplet formation, and they should be considered in climate models.

  16. XPS study of ZnO-based varistor materials

    SciTech Connect

    Kostikov, Yu.P.; Malikov, V.A.; Kuz`mina, E.G.

    1994-06-01

    Many articles are devoted to the study of ZnO-based varistor materials. But an adequate model of the constitution of these materials, describing the entire variety of chemical processes proceeding during their formation, does not yet exist. The absence of such a model and lack of knowledge about the chemistry of these materials lead to the introduction of up to ten dopants in their formulations however, the effect of each of these dopants on the material properties may be unclear. It is possible to resolve this problem only through systematic study of the electronic structure of these materials, of the redox processes which determine the formation of the electronic structure of materials, and of the effect of dopants and impurities on redox processes both directly and through the formation of the ceramic sample microstructure. This work is devoted to the XPS study of zinc oxide doped with cobalt and praseodymium oxides.

  17. PAC and XPS studies of II-VI compounds

    NASA Astrophysics Data System (ADS)

    Swanson, M. L.; Hughes, W. C.; Austin, J. C.; Choi, S. S.

    The perturbed angular correlation (PAC) method has considerable potential for studying near-surface defects of materials on a microscopic scale, especially in combination with standard surface techniques. We have characterized the near-surface and surface regions of II-VI compounds using PAC and X-ray photoelectron spectroscopy (XPS). PAC was used to identify point defect complexes containing the radioactive In-111 probe atoms, which were diffused into Cd(0.96)Zn(0.04)Te, Cd(0.8)Mn(0.2)Te, and Hg(0.79)Cd(0.21)Te (MCT) samples under vacuum from 200 to 550 C. After the Cd(Zn)Te samples were annealed at 450 C for 30 min, 60% of the In atoms occupied unique non-cubic sites, characterized by an interaction frequency Nu(sub Q) = 60 MHz and an asymmetry parameter eta = 0.2. These sites were attributed to In-(cadmium vacancy) complexes, since this signal was eliminated by subsequent annealing in a cadmium atmosphere. Similar results were obtained for the Cd(Mn)Te samples, but the vacancy complex occurred at a lower annealing temperature. The XPS data for Cd(Mn)Te showed that its oxide characteristics differed considerably from those of CdTe. Although oxide formation of CdTe occurs very lowly after sputter cleaning, a significant Te-O layer was formed on the Cd(Mn)Te surfaces after only 10 min exposure to air. In addition, deionized water removed the native oxide completely for CdTe but not for Cd(Mn)Te. For MCT, annealing at 350 C caused the formation of two defect complexes, characterized by frequencies of 83 and 92 MHz, and eta is approximately equal 0.1. These PAC signals vanished after annealing under a mercury atmosphere, indicating that they were also due to In-vacancy complexes.

  18. Neutralization epitopes on rotavirus SA11 4fM outer capsid proteins.

    PubMed Central

    Gorziglia, M; Larralde, G; Ward, R L

    1990-01-01

    The VP7 and VP4 genes of seven antigenic mutants of simian rotavirus SA11 4fM (serotype 3) selected after 39 passages in the presence of SA11 4fM hyperimmune antiserum, were sequenced. Nucleotide sequence analysis indicated the following. (i) Twice as many amino acid substitutions occurred in the VP7 protein than in VP4, which has a molecular weight twice that of VP7. (ii) Most amino acid changes that occurred clustered in six variable regions of VP7 and in two variable regions of VP4; these variable regions may represent immunodominant epitopes. (iii) Most amino acid substitutions that occurred in VP7 and VP4 of these mutants were also observed in antigenic mutants selected with neutralizing monoclonal antibodies (NMAbs); however, some amino acid substitutions occurred that were not selected for NMAbs. (iv) On VP7, some of the neutralization epitopes appeared to be interrelated because amino acid substitution in one site affected binding of specific NMAbs to other sites, while other neutralization epitopes on VP7 appeared to be independent, in that amino acid substitution in one site did not affect the binding of NMAbs to another distant site. Images PMID:1696640

  19. Hyperfine structure of the odd-parity configuration 4f95d in singly ionized terbium

    NASA Astrophysics Data System (ADS)

    Stefanska, D.; Furmann, B.

    2017-10-01

    Within this work experimental investigations of the hyperfine structure for the odd-parity levels belonging to the configuration 4f95d in Tb II were performed. Out of 15 known electronic levels in this configuration, 12 were examined in this context, 11 of them for the first time. Altogether 25 transitions were studied with the odd-parity levels under investigation involved as the lower levels and another 4 transitions involving the previously known odd-parity levels, belonging to the configuration 4f96s. As a by-product, also the hyperfine structure constants for the upper even-parity levels were determined, which in most cases could be compared to the earlier literature data. Semi-empirical calculations of the fine- and the hyperfine structure were performed in single configuration basis. Also ab initio calculations of the hyperfine structure parameters were carried out. Results of the semi-empirical analysis should be considered preliminary because of the scarcity of the available experimental data, in particular the low number of the known electronic levels in the configuration studied.

  20. Self-hole-doping-induced superconductivity in KCa2Fe4As4F2

    NASA Astrophysics Data System (ADS)

    Wang, Guangtao; Wang, Zhenwei; Shi, Xianbiao

    2016-11-01

    The electronic structure, magnetism, Fermi surface nesting, and bare susceptibility of the superconductor KCa2Fe4As4F2 are discussed in relation to the Fe-pnictide superconductors based on the first-principle calculations. There are ten bands crossing the Fermi level in the nonmagnetic (NM) states, resulting in six hole-like Fermi surface (FS) sheets along the Γ\\text-Z line and four electron-like FS sheets along the X\\text-P line. It is more complicated than other FeAs-based superconductors, showing multi-bands character. Fixed spin moment calculations and the total energies of different magnetic phase indicate that KCa2Fe4As4F2 has a strong tendency towards magnetism, i.e., the stripe antiferromagnetic state. But the self-hole-doping suppressed the spin-density wave state, and then induced superconductivity in the parent compound. Such self-doping strategy may be used for future exploration of new superconductors.

  1. Investigations on Pva:. NH4F: ZrO2 Composite Polymer Electrolytes

    NASA Astrophysics Data System (ADS)

    Radha, K. P.; Selvasekarapandian, S.; Karthikeyan, S.; Sanjeeviraja, C.

    2013-07-01

    Composite polymer electrolytes have been prepared using Poly (vinyl alcohol), ammonium fluoride, nanofiller ZrO2 by solution casting technique. The amorphous nature of the composite polymer electrolyte has been confirmed by XRD analysis. FTIR analysis confirms the complex formation among the polymer, salt and nanofiller. The maximum ionic conductivity for 85 PVA:15 NH4F has been found to be 6.9 × 10-6 Scm-1 at ambient temperature. In the present work, the addition of 2 mol% nanofilller ZrO2 to the electrolyte 85PVA:15NH4F enhances the conductivity to 3.4 × 10-5 Scm-1. The temperature dependence of the conductivity of composite polymer electrolytes obeys Arrhenius relation. In the modulus spectra, there is a long tail at low frequencies which is an evidence for large capacitance associated with the electrodes. In the high frequency region, ∈'(ω) value saturates and giving rise to the dielectric constant of the material.

  2. Relevance of NH4F in acid digestion before ICP-MS analysis.

    PubMed

    Mariet, Clarisse; Belhadj, Oulfa; Leroy, Stéphanie; Carrot, Francine; Métrich, Nicole

    2008-10-19

    In order to implement a simpler, less expensive and more safe sample dissolution procedure, we have substituted the HF-HClO(4) mixture by NH(4)F. By testing three certified reference materials, lichen 336, basalt BE-N, soil 7, it was found that the three-reagents digestion without HF and HClO(4) (HNO(3)+H(2)O(2)+NH(4)F was used) was very effective for the pretreatment of ICP-MS measurement. The comparison was based on the measurement results and their uncertainties. All are reference material for amount contents of different trace elements. The accuracy and precision of the developed method were tested by replicate analyses of reference samples of established element contents. The accuracy of the data as well as detection limits (LODs) vary among elements but are usually very good (accuracy better than 8%, LODs usually below 1 microg/g in solids). ICP-MS capabilities enable us to determine routinely 13 and 16 minor and trace elements in basalt and soil.

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

    PubMed Central

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

    2016-01-01

    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 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 hybridization of dysprosium double-decker phthalocyanine 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 have in mediating electronic and magnetic coupling and in accessing many-body quantum states. PMID:27666413

  4. 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.

  5. Li2B3O4F3, a new lithium-rich fluorooxoborate

    NASA Astrophysics Data System (ADS)

    Pilz, Thomas; Nuss, Hanne; Jansen, Martin

    2012-02-01

    The new lithium fluorooxoborate, Li2B3O4F3, is obtained by a solid state reaction from LiBO2 and LiBF4 at 553 K and crystallizes in the acentric orthorhombic space group P212121 (no. 19) with the cell parameters a=4.8915(9), b=8.734(2), and c=12.301(2) Å. Chains of fluorinated boroxine rings along the b axis consists of BO3 triangles and BO2F2 as well as BO3F 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 Li2B3O4F3 at temperatures above 573 K leads to conversion into Li2B6O9F2. The title compound is an ionic conductor with the highest ion conductivity among the hitherto know lithium fluorooxoborates, with conductivities of 1.6×10-9 and 1.8×10-8 S cm-1 at 473 and 523 K, respectively.

  6. XPS Studies of Yb14MnSb11 and Yb14ZnSb11

    SciTech Connect

    Holm, A P; Ozawa, T C; Kauzlarich, S M; Morton, S A; Waddill, G D; Pickett, W E; Tobin, J G

    2003-10-02

    Measurements of core and valence electronic states of single crystals of the rare earth transition metal Zintl phases Yb{sub 14}MnSb{sub 11} and Yb{sub 14}ZnSb{sub 11} were performed using the X-ray photoelectron spectroscopy station of Beamline 7 at the Advanced Light Source. Sample surfaces of Yb{sub 14}MnSb{sub 11} and Yb{sub 14}ZnSb{sub 11} were measured as received, after Ar{sup +} ion bombardment, and after cleaving in situ. Detailed analysis of the clean Mn and Zn analog sample surfaces reveal a significant contribution of both Yb{sup 3+} and Yb{sup 2+} 4f states in the valence band region for the Zn analog and no contribution of Yb{sup 3+} states to the valence band for the Mn analog. This result is predicted for the Zn analog by Zintl counting rules, and single crystal X-ray diffraction studies presented here also support the mixed valency of Yb for Yb{sub 14}ZnSb{sub 11}. Further detailed analysis of the core and valence band structure of both Yb{sub 14}MnSb{sub 11} and Yb{sub 14}ZnSb{sub 11} will be presented.

  7. 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.

  8. Anion-Dependent Assembly of Heterometallic 3d-4f Clusters Based on a Lacunary Polyoxometalate.

    PubMed

    Cai, Jing; Zheng, Xiu-Ying; Xie, Jing; Yan, Zhi-Hao; Kong, Xiang-Jian; Ren, Yan-Ping; Long, La-Sheng; Zheng, Lan-Sun

    2017-07-17

    A series of heterometallic 3d-4f clusters, formulated as Na17[Ln3(H2O)5Ni(II)(H2O)3(Sb4O4)(SbW9O33)3(Ni(II)W6O24)(WO2)3(CH3COO)]·(H2O)65 [abbreviated as Ln3Ni2, where Ln = La(3+) (1), Pr(3+) (2), and Nd(3+) (3)], K5Na11[Ln3(H2O)3Ni(II)3(H2O)6(SbW9O33)3(WO4)(CO3)]·(H2O)40 [abbreviated as Ln3Ni3, where Ln = La(3+) (4), Pr(3+) (5), and Nd(3+) (6)], and K3Na27[Ln3Ni(II)9(μ3-OH)9(SbW9O33)2(PW9O34)3(CH3COO)3]·(H2O)80 [abbreviated as Ln3Ni9, where Ln = Dy(3+) (7) and Er(3+) (8)], were obtained through the reaction of the lacunary {SbW9O33} precursor with Ln(NO3)3·6H2O and NiCl2·6H2O in a NaAc/HAc buffer in the presence of different anions. Single-crystal X-ray structure analysis revealed that compounds 1-3 possessed tetrameric architectures featuring three Keggin-type {SbW9O33} and one Anderson-type {Ni(II)W6O24} building blocks encapsulating one {Sb4O4} cluster, three WO2 units, three Ln(3+) metal ions, and two Ni(2+) metal ions. Compounds 4-6 displayed cyclic trimeric aggregates of three {SbW9O33} units enveloping one CO3(2-)-templated trinuclear [Ln3(CO3)](7+) and one WO4(2-)-templated [Ni(II)3(WO4)](+) unit. Compounds 7 and 8 exhibited unique pentameric architectures that featured three 3d-4f cubane clusters of {LnNi3(μ3-OH)3} capped by two {SbW9O33} and three {PW9O34} building blocks. Interestingly, the structural regulation of the heterometallic 3d-4f clusters in the polyoxometalate systems with trimers, tetramers, and pentamers was realized by introducing different anions.

  9. 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

    2015-04-06

    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.

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

    PubMed Central

    Nair, Sunil; Stockert, O.; Witte, U.; Nicklas, M.; Schedler, R.; Kiefer, K.; Thompson, J. D.; Bianchi, A. D.; Fisk, Z.; Wirth, S.; Steglich, F.

    2010-01-01

    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. PMID:20457945

  11. Series of chiral interpenetrating 3d-4f heterometallic MOFs: Luminescent sensors and magnetic properties

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolei; Chen, Chen; Liu, Xiaoli; Gao, Peng; Hu, Ming

    2017-09-01

    Series of chiral 3d-4f heterometallic MOFs based on a multidentate terpyridyl carboxylic acid ligand have been synthesized under the solvothermal conditions, namely, [LnZnL(CO3)2(H2O)]n (Ln = Eu (1), Gd (2), Dy (3), Ho (4), Er (5), Tm (6), Yb (7), Lu (8)) (HL = 4‧-(4-carboxyphenyl)-2,2‧:6‧,2″-terpyridine). Compounds 1-8 were structurally characterized by the elemental analyses, infrared spectra, and single crystal X-ray diffractions. Compounds 1-8 exhibit the chiral interpenetrating 3D frameworks. Interestingly, 1 can serve as the luminescent sensor to detect nitrobenzene molecules with high sensitivity. The investigations on CD spectra of single crystals clearly assigned the Cotton effect, indicating that there exist two chiral enantiomers of 1-8 in the course of crystallization. The magnetic properties of 2 and 7 were exploited, respectively.

  12. Nonlinear optical measurements using a 4f coherent imaging system with phase objects

    SciTech Connect

    Boudebs, G.; Cherukulappurath, S.

    2004-05-01

    We report a one-laser-shot measurement technique using a phase object at the entry of a 4f coherent imaging system to characterize the value of the nonlinear refractive index of materials placed in the Fourier plane of the setup. Experimental and simulated images are presented here in order to validate our approach. We show that the use of a quarter-wavelength dephasing object maximizes the transmission variations in the detected image. We show also that the use of phase objects increases significantly the sensitivity of the measurement compared to top-hat beams (by a factor of 6). Moreover, by adding this type of object at the entry of our imaging system it is possible to determine the sign of the refractive nonlinearity.

  13. 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.

  14. Synthesis and superconducting properties of fluorinated La 2CuO 4 using NH 4F

    NASA Astrophysics Data System (ADS)

    Adachi, S.; Wu, X.-J.; Tamura, T.; Tatsuki, T.; Tokiwa-Yamamoto, A.; Tanabe, K.

    1997-02-01

    Superconducting La 2CuO 4-δF y samples were synthesized by heating La 2CuO 4 together with a fluorinating reagent, NH 4F, at 240°C in flowing oxygen gas. Bulk superconductivity with Tc = 42 K in the samples was confirmed by DC magnetic susceptibility measurements. The enhancement in the orthorhombicity of the K 2NiF 4 phase ( a = 5.319 Å, b = 5.442 Å, c = 13.20 Å) was observed. The lower and upper critical fields, Hc1(0) and Hc2(0), for the La 2CuO 4-δF y were roughly determined to be 98 Oe and 600 kOe, respectively.

  15. Observation of orbital order in the half-filled 4f Gd compound

    DOE PAGES

    Jang, H.; Kang, B. Y.; Cho, B. K.; ...

    2016-11-18

    Half-filled electron systems, even with the maximized spin angular moment, have been given little attention because of their zero-orbital angular moment according to Hund’s rule. Nevertheless, there are several measurements that show evidence of a nonzero orbital moment as well as spin-orbit coupling. Here we report for the first time the orbital order in a half-filled 4f-electron system GdB4, using the resonant soft x-ray scattering at Gd M4,5-edges. Furthermore, we discovered that the development of this orbital order is strongly coupled with the antiferromagnetic spin order. Lastly, these results clearly demonstrate that even in half-filled electron systems the orbital angularmore » moment can be an important parameter to describe material properties, and may provide significant opportunities for tailoring new correlated electron systems.« less

  16. Three-dimensional photoacoustic imaging system with a 4f aspherical acoustic lens

    NASA Astrophysics Data System (ADS)

    Jen, En; Lin, Hsintien; Chiang, Huihua Kenny

    2016-08-01

    Photoacoustic (PA) imaging is a modality for achieving high-contrast images of blood vessels or tumors. Most PA imaging systems use complex reconstruction algorithms under conventional linear array transducers. We introduced the optical simulating method to improve the acoustic lens design and obtain a PA imaging system with improved spatial revolution (a 0.5-mm point spread function and a lateral image resolution of more than 1 mm) is realized using a 4f aspherical acoustic lens. The acoustic lens approach improved the image resolution and enabled direct reconstruction of three-dimensional (3-D) PA images. The system demonstrated a lateral resolution of more than 1 mm, a field of view of 8.5 deg, and a depth of focus of 10 mm. The system displays great potential for developing a real-time 3-D PA camera system for biomedical ultrasound imaging applications.

  17. Multiple path interference and differential modal delay reduction using spatial filters in a 4F system.

    PubMed

    Wang, Hao; Kumar, Shiva; Xu, Changqing

    2008-05-01

    Multiple path interference (MPI) and differential modal delay (DMD) are two major impairments in fiber optic communication systems. MPI can be found in a few mode fibers in which a higher order mode propagates as a weak replica of the signal and interferes with the fundamental mode at the output of the fiber link. DMD in multimode fibers (MMF) leads to intersymbol interference, which limits the bit rate-distance product of the system. A simple method is proposed to reduce MPI and DMD effects using spatial filters in a 4F system. Higher order modes have higher spatial frequency components. Therefore by choosing a proper spatial filter with a suitable bandwidth, a fraction of the unwanted higher order modes can be suppressed, and therefore MPI and DMD effects can be reduced.

  18. Observation of Orbital Order in the Half-Filled 4 f Gd Compound

    NASA Astrophysics Data System (ADS)

    Jang, H.; Kang, B. Y.; Cho, B. K.; Hashimoto, M.; Lu, D.; Burns, C. A.; Kao, C.-C.; Lee, J.-S.

    2016-11-01

    Half-filled electron systems, even with the maximized spin angular moment, have been given little attention because of their zero-orbital angular moment according to Hund's rule. Nevertheless, there are several measurements that show evidence of a nonzero orbital moment as well as spin-orbit coupling. Here we report for the first time the orbital order in a half-filled 4 f -electron system GdB4, using the resonant soft x-ray scattering at Gd M4 ,5-edges. Furthermore, we discovered that the development of this orbital order is strongly coupled with the antiferromagnetic spin order. These results clearly demonstrate that even in half-filled electron systems the orbital angular moment can be an important parameter to describe material properties, and may provide significant opportunities for tailoring new correlated electron systems.

  19. 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.

  20. New flow boiling heat transfer correlation for CFC-114 and C{sub 4}F{sub 10}

    SciTech Connect

    Szady, A.J.

    1995-08-01

    The flow boiling tests being conducted at Cudo Technologies, Ltd. in Lexington, Kentucky are a part of The GDP Coolant Replacement Project. The tests are to be done with two alternates, C{sub 4}F{sub 10} and C{sub 4}F{sub 8}, as well as CFC-114. So far, tests were conducted with CFC-114 and C{sub 4}F{sub 10}. The CFC-114 data by Cudo shows better heat transfer performance than that predicted by the codes used in the numerical model which were based on a superposition model. The data was applied to an asymptotic model developed by Steiner and Taborek. The new correlation developed seems to fit better with the Cudo data as well as the Paducah cell test data. The model will be further investigated when C{sub 4}F{sub 8} data is available.

  1. Heptanuclear 3d-4f cluster complexes with a coaxial double-screw-propeller topology and diverse magnetic properties.

    PubMed

    Liu, Cai-Ming; Zhang, De-Qing; Zhu, Dao-Ben

    2010-12-21

    Two novel coaxial double-screw-propeller heptanuclear 3d-4f cluster complexes are ferromagnetic: one exhibits a large magnetocaloric effect while the other a magnetic relaxation behavior, depending on the lanthanoid ions used.

  2. Temperature Dependence of the Yb 4f Spectra in Yb4Bi3 Probed by Photoemission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Harada, Hideyuki; Sekiyama, Akira; Suga, Shigemasa; Imada, Shin; Muro, Takayuki; Jung, Ran-Ju; Matsuda, Kyoko; Takagi, Hiroshi; Ochiai, Akira; Suzuki, Takashi; Harima, Hisatomo

    1999-08-01

    We have performed a photoemission study of Yb4Bi3. Thevalence band spectra have shown no multiplet structures associatedwith the trivalent Yb and revealed that the mean valence of the Yb ionis very close to 2.0. The divalent Yb 4f spectra have shown strongsurface components besides weak but sharp bulk components. The surface4f level shift is about 0.45 eV (300 K), 0.48 eV (150 K) and0.54 eV (20 K). A clear energy shift of the bulk Yb 4f peaks towardEF with decreasing temperature has been observed, althoughYb4Bi3 shows neither phase transition nor crossover. Such anunusual peak shift of the bulk component may originate from a changeof the lattice constant with decreasing temperature. The observednarrowing of the bulk 4f peaks is thought to be due to a phononbroadening (˜7 k BT).

  3. Quantitative moment study and coupling of 4 f rare earth and 3 d metal by transmitted electrons

    NASA Astrophysics Data System (ADS)

    Fu, X.; Warot-Fonrose, B.; Arras, R.; Dumesnil, K.; Serin, V.

    2016-10-01

    We report a simultaneous investigation of 3 d and 4 f magnetic moments by exploring the Fe -L2 ,3 and Dy -M4 ,5 electron energy-loss edges of a DyF e2/YF e2 superlattice using the energy-loss magnetic chiral dichroism (EMCD) technique. Specific EMCD sum rules for M4 ,5 edges were established and carefully applied to the dichroic signal at Dy -M4 ,5 edges, giving an orbital to the effective spin moment ratio of 5.1 ±1.8 . With dynamic diffraction effects considered, the opposite signs of Fe -L3 and Dy -M5 dichroic peaks unambiguously indicate the antiparallel alignment of net Fe 3 d and Dy 4 f moments. The EMCD technique is shown to be an effective tool to locally characterize the 4 f moment of rare earth elements and study 3 d -4 f moment coupling.

  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. Investigation of adhesion between molybdenum and polysilazane by XPS

    NASA Astrophysics Data System (ADS)

    Amouzou, Dodji; Fourdrinier, Lionel; Sporken, Robert

    2015-07-01

    Here, we investigate the interface between polysilazane (PSZ) coatings and Mo films for understanding adhesion. Two kinds of Mo/PSZ samples are investigated (the well-adhered samples and the non-adhered samples) and the chemical environments of their interfaces are compared. For some investigations, ultra-thin Mo films (2-5 nm) are deposited on PSZ coatings to probe the interface directly by X-ray photoelectron spectroscopy (XPS) and to avoid long sputtering times in depth profiling of Mo films. It was found that the sputtered Mo films systematically adhere well to PSZ coatings. The good adhesion arises from a formation of molybdenum oxycarbonitride or molybdenum carbonitride ceramics through covalent bonding between atoms from PSZ and Mo at the interface. The nature of ceramic newly formed at the interface between PSZ and Mo films depends on deposition conditions and can lead to cohesion failure in PSZ coatings. We demonstrated that the adhesion failure observed for some samples does not occur due to the absence of bonding between atoms at interface of Mo/PSZ but may result from the chemical change.

  6. 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

  7. Charcot-Marie-Tooth type 4F disease caused by S399fsx410 mutation in the PRX gene.

    PubMed

    Kabzinska, D; Drac, H; Sherman, D L; Kostera-Pruszczyk, A; Brophy, P J; Kochanski, A; Hausmanowa-Petrusewicz, I

    2006-03-14

    Charcot-Marie-Tooth type 4F disease (CMT4F) is an autosomal recessive neuropathy caused by mutations in the PRX gene. To date, only seven mutations have been identified in the PRX gene. In this study, the authors report a novel S399fsX410 mutation in the PRX gene and its effects at the protein level, which was identified in an 8-year-old patient with early-onset CMT disease.

  8. Synthesis and electrochemical performance of Li2Co1- x M x PO4F (M = Fe, Mn) cathode materials.

    PubMed

    Khasanova, Nellie R; Drozhzhin, Oleg A; Fedotov, Stanislav S; Storozhilova, Darya A; Panin, Rodion V; Antipov, Evgeny V

    2013-01-01

    In the search for high-energy materials, novel 3D-fluorophosphates, Li2Co1- x Fe x PO4F and Li2Co1- x Mn x PO4F, have been synthesized. X-ray diffraction and scanning electron microscopy have been applied to analyze the structural and morphological features of the prepared materials. Both systems, Li2Co1- x Fe x PO4F and Li2Co1- x Mn x PO4F, exhibited narrow ranges of solid solutions: x ≤ 0.3 and x ≤ 0.1, respectively. The Li2Co0.9Mn0.1PO4F material demonstrated a reversible electrochemical performance with an initial discharge capacity of 75 mA·h·g(-1) (current rate of C/5) upon cycling between 2.5 and 5.5 V in 1 M LiBF4/TMS electrolyte. Galvanostatic measurements along with cyclic voltammetry supported a single-phase de/intercalation mechanism in the Li2Co0.9Mn0.1PO4F material.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. XPS study of the hematite-aqueous solution interface

    SciTech Connect

    Shchukarev, Andrei; Boily, Jean F.

    2008-04-01

    The electric double layer at the surface of micrometer-sized hematite platelets dominated by the basal {001} and the edge {012} planes was investigated using the cryogenic XPS technique. Thoroughly dialysed hematite suspensions revealed the presence of surface-bound sodium (2.2 at. %) and chloride (0.4 at. %). Suspensions in 10 mM and 100 mM NaCl revealed additional uptake of sodium and chloride. The Na/Cl atomic ratio follows the pH dependence found with previous studies of goethite, manganite and gibbsite. An excess of Cl- was demonstrated at positively charged hematite surface, and Na+ at negatively charged surfaces. The surface coverage of electrolyte ions was also shown to play an important role on the presence of water at the interface. At low ionic strength the water content was about of 10 at. %, yielding a water/counter-ions atomic ratio of about 3-6, depending on pH. At 100 mM NaCl, however, the large atomic concentrations of sodium and chloride resulted in a water content of about 25 at. %, nonetheless yielding a water/counter-ion atomic ratio about 1. The presence of 100 mM CsCl, on the other hand, yielded the same amount of surface-bound water as in 10 mM NaCl due to a lower surface coverage for Cs and to its weaker affinity for water. Finally, a non-equilibrated hematite sample at pH 4 enabled a description the formation of the electric double layer upon addition of 100 mM NaCl to an electrolyte-free suspension

  14. XPS chemical analysis of tholins: the oxygen contamination

    NASA Astrophysics Data System (ADS)

    Carrasco, N.; Jomard, F.; Vigneron, J.; Cernogora, G.

    2013-12-01

    In Titan's atmosphere, solid organic aerosols are initiated in the upper atmosphere by the photo-dissociation and photo-ionization of N2 and CH4. In order to simulate this complex chemistry several experimental setups have been built, among them plasma experiments. The aerosol analogues produced in such plasma discharges contain oxygen, as a few percents of the elemental composition, despite the absence of oxygen source in the reactive medium [1]. The present study aims at studying the origin of such systematic oxygen incorporation in tholins. A low pressure (0.9mbar) RF CCP discharge is used described in [2]. Gas mixtures of N2 and CH4 (from 1 to 10% of CH4) are injected continuously. The plasma discharge leads to the production of analogues of Titan's atmospheric aerosols: both as grains in the volume [1] and as thin films on the surface of the reactor [3]. SiO2 substrates of 1cm diameter and 1mm thickness are placed on the grounded electrode of the discharge. Organic films are deposited during 2 hours in order to have films thickness less than 1μm. After the two hours, samples are recovered at ambient air for ex-situ analysis. Two complementary analyses are performed to analyse the thin film chemical composition: XPS and SIMS, in order to probe both the surface and depth profile. References [1] Sciamma-O'brien E., Carrasco N., Szopa C., Buch A., Cernogora G. Icarus 209, 2 (2010) 704-714 [2] Alcouffe G., Cavarroc M., Cernogora G., Ouni F., Jolly A., Boufendi L., Szopa C. Plasma Sources Science and Technology 19, 1 (2010) 015008 (11pp) [3] Mahjoub A., Carrasco N., Dahoo P.-R., Gautier T., Szopa C., Cernogora G. Icarus 221, 2 (2012) 670-677.

  15. 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).

  16. 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.

  17. 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

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

    PubMed

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

    2014-06-01

    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 knockouts 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Influence of CYP4F2 genotype on warfarin dose requirement-a systematic review and meta-analysis.

    PubMed

    Liang, Ruijuan; Wang, Chunling; Zhao, Hong; Huang, Jie; Hu, Dayi; Sun, Yihong

    2012-07-01

    Warfarin is a commonly used oral anticoagulant and the dosage is individually adjusted on the basis of the international normalized ratio (INR) monitoring. It is well known that gene polymorphisms of CytochromeP450 (CYP) 2C9 gene and the vitamin K epoxide reductase complex 1 (VKORC1) were significantly associated with warfarin dose. However, the association between Cytochrome P450 4F2 (CYP4F2) polymorphism and warfarin dose requirement is still controversial. This study was to investigate the influence of the CYP4F2 polymorphism, V433M (rs2108622) on warfarin dose for patients by meta-analysis. Strict inclusion and exclusion criteria were set, and the studies prior to December 19, 2010 were searched in PubMed, EMBASE and CNKI. References were examined and experts of primary studies were consulted for additional information. Revman 5.0.2 software was used to analyze the relationship between warfarin maintenance dose and CYP4F2 polymorphism Thirteen studies were included in the meta-analysis which consisted of Caucasian, Asian and African populations. Compared to individuals with the homozygous CYP4F2 genotype (CC), carriers of CT, TT genotypes required 10.0% (95% confidence interval(CI) 4.0-15.0) and 21.0% (95% CI 9.0-33.0) higher warfarin doses respectively (P value <0.05). In addition, T carriers required 11.0% (95% CI 6.0-17.0) higher warfarin dose than CC genotype. Our study showed that polymorphism of CYP4F2 had a moderate but statistically significant association with the variation of interindividual warfarin dose. However, whether CYP4F2 can improve the prediction of warfarin dose warrants need further investigation when combined with environmental factors. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. 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.

  1. 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.

  2. 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.

  3. XPS study of nitrogen dioxide adsorption on metal oxide particle surfaces under different environmental conditions.

    PubMed

    Baltrusaitis, Jonas; Jayaweera, Pradeep M; Grassian, Vicki H

    2009-10-01

    The adsorption of nitrogen dioxide on gamma aluminium oxide (gamma-Al(2)O(3)) and alpha iron oxide (alpha-Fe(2)O(3)) particle surfaces under various conditions of relative humidity, presence of molecular oxygen and UV light has been investigated. X-Ray photoelectron spectroscopy (XPS) is used to monitor the different surface species that form under these environmental conditions. Adsorption of NO(2) on aluminum oxide particle surfaces results primarily in the formation of surface nitrate, NO(3)(-) with an oxidation state of +5, as indicated by a peak with binding energy of 407.3 eV in the N1s region. An additional minority species, sensitive to the presence of relative humidity and molecular oxygen, is also observed in the N1s region with lower binding energy of 405.9 eV. This peak is assigned to a surface species in the +4 oxidation state. When irradiated with UV light, other species form on the surface. These surface-bound photochemical products all have lower binding energy, between 400 and 402 eV, indicating reduced nitrogen species in the range of N oxidations states spanning +1 to -1. Co-adsorbed water decreases the amount of these reduced surface-bound products while the presence of molecular oxygen completely suppresses the formation of all reduced nitrogen species on aluminum oxide particle surfaces. For NO(2) on iron oxide particle surfaces, photoreduction is enhanced relative to gamma-Al(2)O(3) and surface bound photoreduced species are observed under all environmental conditions. Complementing the experimental data, N1s core electron binding energies (CEBEs) were calculated using DFT for a number of nitrogen-containing species in the gas phase and adsorbed on an Al(8)O(12) cluster. A range of CEBEs is calculated for various nitrogen species in different adsorption modes and oxidation states. These calculated values are discussed in light of the peaks observed in the XPS N1s region and the possible species that form following NO(2) adsorption and

  4. Quantum Chaos and Quantum Magnetism with 4f-Submerged-Shell Atoms

    NASA Astrophysics Data System (ADS)

    Kotochigova, Svetlana; Makrides, Constantinos; Petrov, Alexander; Tiesinga, Eite

    2015-05-01

    We report on a theoretical investigation of the quantum level statistics of ultra-cold gases of open-4f-shell Er and Dy atoms based on a recently-developed computational model that can evaluate their weakly-bound molecular structure. A large interaction anisotropy between these atoms due to the large orbital angular momentum of their electrons creates a rich electronic structure. We find that this structure and their relatively large mass generates an extremely dense spectrum of rotational and vibrational levels near the dissociation limits for magnetic field strengths up to 100 Gauss. We analyzed these bound-state energy spectra and Feshbach resonance locations for signatures of chaos. For example, we find that in contrast to many other atomic systems these weakly-bound molecules already have a chaotic level distribution even in the absence of a magnetic field. We also report on the feasibility to detect quantum magnetism in a system where pairs of erbium or dysprosium are trapped in sites of an optical lattice. We predict the existence of spinor oscillations, where the population of magnetic sub levels oscillates in time due to the presence of anisotropic atomic interactions. Their periods can be used to characterize these interactions at zero and small magnetic field. Research at Temple University is supported by AFOSR (FA9550-14-1-0321) and NSF (No. PHY-1308573) grants.

  5. Pressure-enhanced superconductivity in Eu3Bi2S4F4

    DOE PAGES

    Luo, Yongkang; Zhai, Hui -Fei; Zhang, Pan; ...

    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

  6. Dynamic magnetic excitations in 3d and 4f atoms and clusters

    NASA Astrophysics Data System (ADS)

    Balashov, Timofey; Miyamachi, Toshio; Schuh, Tobias; Märkl, Tobias; Bresch, Christopher; Wulfhekel, Wulf

    2014-12-01

    Spins in magnetic nanostructures can be excited by an electric current. In the inelastic scattering events, the spin of a tunneling electron provided by a scanning tunneling microscope may be flipped and angular momentum is transferred to the magnetic system. We used this technique to determine magnetic anisotropies and exchange couplings in 3d transition and 4f rare earth metal atoms and clusters on surfaces. Further, we discuss that the magnetic anisotropy, i.e. the zero field splitting, in rare earth atoms requires a fully relativistic description, in which not only the spin of the atoms but also their orbital angular momentum is taken into account. When describing the magnetic anisotropy with the Hamiltonian including all Stevens operators and combining it with spin flip scattering by conduction and tunneling electrons, we find that long spin lifetimes are theoretically expected for specific total angular momenta and crystal field symmetries and show experimental evidence that such a situation is realized in Ho on Pt(111).

  7. Anomalous Eu valence state and superconductivity in undoped Eu3Bi2S4F4.

    PubMed

    Zhai, Hui-Fei; Zhang, Pan; Wu, Si-Qi; He, Chao-Yang; Tang, Zhang-Tu; Jiang, Hao; Sun, Yun-Lei; Bao, Jin-Ke; Nowik, Israel; Felner, Israel; Zeng, Yue-Wu; Li, Yu-Ke; Xu, Xiao-Feng; Tao, Qian; Xu, Zhu-An; Cao, Guang-Han

    2014-10-29

    We have synthesized a novel europium bismuth sulfofluoride, Eu3Bi2S4F4, by solid-state reactions in sealed evacuated quartz ampules. The compound crystallizes in a tetragonal lattice (space group I4/mmm, a = 4.0771(1) Å, c = 32.4330(6) Å, and Z = 2), in which CaF2-type Eu3F4 layers and NaCl-like BiS2 bilayers stack alternately along the crystallographic c axis. There are two crystallographically distinct Eu sites, Eu(1) and Eu(2) at the Wyckoff positions 4e and 2a, respectively. Our bond valence sum calculation, based on the refined structural data, indicates that Eu(1) is essentially divalent, while Eu(2) has an average valence of ∼ +2.64(5). This anomalous Eu valence state is further confirmed and supported, respectively, by Mössbauer and magnetization measurements. The Eu(3+) components donate electrons into the conduction bands that are mainly composed of Bi 6px and 6py states. Consequently, the material itself shows metallic conduction and superconducts at 1.5 K without extrinsic chemical doping.

  8. CXCR4 antagonist 4F-benzoyl-TN14003 inhibits leukemia and multiple myeloma tumor growth.

    PubMed

    Beider, Katia; Begin, Michal; Abraham, Michal; Wald, Hanna; Weiss, Ido D; Wald, Ori; Pikarsky, Eli; Zeira, Evelyne; Eizenberg, Orly; Galun, Eithan; Hardan, Izhar; Engelhard, Dan; Nagler, Arnon; Peled, Amnon

    2011-03-01

    The chemokine receptor CXCR4 and its ligand CXCL12 are involved in the progression and dissemination of a diverse number of solid and hematological malignancies. Binding CXCL12 to CXCR4 activates a variety of intracellular signal transduction pathways that regulate cell chemotaxis, adhesion, survival, proliferation, and apoptosis. Here, we demonstrate that the CXCR4 antagonist, 4F-benzoyl-TN14003 (BKT140), but not AMD3100, exhibits a CXCR4-dependent preferential cytotoxicity toward malignant cells of hematopoietic origin. BKT140 significantly and preferentially stimulated multiple myeloma apoptotic cell death. BKT140 treatment induced morphological changes, phosphatidylserine externalization, decreased mitochondrial membrane potential, caspase-3 activation, sub-G1 arrest, and DNA double-stranded breaks. In vivo, subcutaneous injections of BKT140 significantly reduced, in a dose-dependent manner, the growth of human acute myeloid leukemia and multiple myeloma xenografts. Tumors from animals treated with BKT140 were smaller in size and weights, had larger necrotic areas and high apoptotic scores. Taken together, these results suggest a potential therapeutic use for BKT140 in multiple myeloma and leukemia patients. Copyright © 2011 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.

  9. Synthesis and Characterization of La 3NbSe 2O 4F 2

    NASA Astrophysics Data System (ADS)

    Brennan, Theodore D.; Mansuetto, Michael F.; Ibers, James A.

    1993-12-01

    Crystals of the unusual oxyfluoroselenide La 3NbSe 2O 4F 2 were obtained during the exploration of the quaternary La/Nb/Cu/Se system. Oxygen was extracted from the silica tube, while fluorine was present as a minor impurity in the La powder. The compound crystallizes in space group D 162 h- Pnma of the orthorhombic system with four formula units in a cell with dimensions: a = 11.290(4), b = 4.001(1), and c = 18.062(4) Å ( T = 113 K). The structure has been determined by single-crystal X-ray methods. The presence of F in the crystals was confirmed by windowless EDAX measurements. The two F sites were distinguished from the four O sites from a combination of the X-ray refinement and a bond-valence parameter calculation made with the program EUTAX. In the structure the Nb atom is octahedrally coordinated while each of the three independent La atoms is in a tricapped trigonal prism. The Nb atom is bound to one Se atom and five O atoms while the three La sites are coordinated by various combinations of Se, O, and F atoms. The NbO 5Se octahedra corner share and the LaSe xO yF z tricapped trigonal prisms face share in the b direction.

  10. Local Symmetry Effects in Actinide 4f X-ray Absorption in Oxides.

    PubMed

    Butorin, Sergei M; Modin, Anders; Vegelius, Johan R; Suzuki, Michi-To; Oppeneer, Peter M; Andersson, David A; Shuh, David K

    2016-04-19

    A systematic X-ray absorption study at actinide N6,7 (4f → 6d transitions) edges was performed for light-actinide oxides including data obtained for the first time for NpO2, PuO2, and UO3. The measurements were supported by ab initio calculations based on local-density-approximation with added 5f-5f Coulomb interaction (LDA+U). Improved energy resolution compared to common experiments at actinide L(2,3) (2p → 6d transitions) edges allowed us to resolve the major structures of the unoccupied 6d density of states (DOS) and estimate the crystal-field splittings in the 6d shell directly from the spectra of light-actinide dioxides. The measurements demonstrated an enhanced sensitivity of the N(6,7) spectral shape to changes in the compound crystal structure. For nonstoichiometric NpO(2-x), the filling of the entire band gap with Np 6d states was observed thus supporting a phase coexistence of Np metal and stoichiometric NpO2 which is in agreement with the tentative Np-O phase diagram.

  11. 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.

  12. The electron shuffle: Cerium influences samarium 4f orbital occupancy in heteronuclear Ce-Sm oxide clusters

    NASA Astrophysics Data System (ADS)

    Kafader, Jared O.; Topolski, Josey E.; Marrero-Colon, Vicmarie; Iyengar, Srinivasan S.; Jarrold, Caroline Chick

    2017-05-01

    The anion photoelectron (PE) spectra along with supporting results of density functional theory (DFT) calculations on SmO-, SmCeOy-, and Sm2Oy- (y = 1, 2) are reported and compared to previous results on CeO- [M. Ray et al., J. Chem. Phys. 142, 064305 (2015)] and Ce2Oy- (y = 1, 2) [J. O. Kafader et al., J. Chem. Phys. 145, 154306 (2016)]. Similar to the results on CexOy- clusters, the PE spectra of SmO-, SmCeOy-, and Sm2Oy- (y = 1, 2) all exhibit electronic transitions to the neutral ground state at approximately 1 eV e-BE. The Sm centers in SmO and Sm2O2 neutrals can be described with the 4f56s superconfiguration, which is analogous to CeO and Ce2O2 neutrals in which the Ce centers can be described with the 4f 6s superconfiguration (ZCe = ZSm - 4). The Sm center in CeSmO2, in contrast, has a 4f6 occupancy, while the Ce center maintains the 4f 6s superconfiguration. The less oxidized Sm centers in both Sm2O and SmCeO have 4f6 6s occupancies. The 4f6 subshell occupancy results in relatively weak Sm-O bond strengths. If this extra 4f occupancy also occurs in bulk Sm-doped ceria, it may play a role in the enhanced O2- ionic conductivity in Sm-doped ceria. Based on the results of DFT calculations, the heteronuclear Ce-Sm oxides have molecular orbitals that are distinctly localized Sm 4f, Sm 6s, Ce 4f, and Ce 6s orbitals. The relative intensity of two electronic bands in the PE spectrum of Sm2O- exhibits an unusual photon energy-dependence, and the PE spectrum of Sm2O2- exhibits a photon energy-dependent continuum signal between two electronic transitions. Several explanations, including the high magnetic moment of these suboxide species and the presence of low-lying quasi-bound anion states, are considered.

  13. Differentiation of Calcium Carbonate Polymorphs by Surface Analysis Techniques – An XPS and TOF-SIMS study

    PubMed Central

    Ni, Ming; Ratner, Buddy D.

    2013-01-01

    Calcium carbonate has evoked interest owing to its use as a biomaterial, and for its potential in biomineralization. Three polymorphs of calcium carbonate, i.e. calcite, aragonite, and vaterite were synthesized. Three conventional bulk analysis techniques, Fourier transform infrared (FTIR), X-ray diffraction (XRD), and SEM, were used to confirm the crystal phase of each polymorphic calcium carbonate. Two surface analysis techniques, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS), were used to differentiate the surfaces of these three polymorphs of calcium carbonate. XPS results clearly demonstrate that the surfaces of these three polymorphs are different as seen in the Ca(2p) and O(1s) core-level spectra. The different atomic arrangement in the crystal lattice, which provides for a different chemical environment, can explain this surface difference. Principal component analysis (PCA) was used to analyze the TOF-SIMS data. Three polymorphs of calcium carbonate cluster into three different groups by PCA scores. This suggests that surface analysis techniques are as powerful as conventional bulk analysis to discriminate calcium carbonate polymorphs. PMID:25031482

  14. Interethnic variability of CYP4F2 (V433M) in admixed population of Roma and Hungarians.

    PubMed

    Sipeky, Csilla; Weber, Agnes; Melegh, Bela I; Matyas, Petra; Janicsek, Ingrid; Szalai, Renata; Szabo, Istvan; Varnai, Reka; Tarlos, Greta; Ganczer, Alma; Melegh, Bela

    2015-07-01

    Pharmacogenetic based dosing recommendations are provided in FDA-approved warfarin label for Caucasians. Evidence of notable difference in dosing algorithms of under-represented populations forced us to explore the genetic variability of CYP4F2 gene in Roma and Hungarian populations. 484 Roma, 493 Hungarian untreated subjects were genotyped for the CYP4F2*3 (rs2108622) variant by PCR-RFLP assay. We firstly report, that frequencies of the CYP4F2 rs2108622 GG, GA, AA genotypes and A allele in the Roma population were 46.5%, 42.6%, 10.9% and 32.2%; in Hungarians 50.1%, 42.2%, 7.7% and 22.8%, respectively. Bearing of two minor alleles of CYP4F2 missense variant (AA genotype) modestly explains inter-ethnic differences of studied populations (p<0.08). CYP4F2*3 (V433M) risk allele frequency of Roma (0.32) was in higher range, and of Hungarians (0.23) in lower range, as compared with other world populations. Roma have an elevated chance for higher mean warfarin dose, besides a decreased risk of major bleeding events in long-term warfarin use. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Heterodimerization of y(+)LAT-1 and 4F2hc visualized by acceptor photobleaching FRET microscopy.

    PubMed

    Kleemola, Maaria; Toivonen, Minna; Mykkänen, Juha; Simell, Olli; Huoponen, Kirsi; Heiskanen, Kaisa M

    2007-10-01

    y(+)LAT-1 and 4F2hc are the subunits of a transporter complex for cationic amino acids, located mainly in the basolateral plasma membrane of epithelial cells in the small intestine and renal tubules. Mutations in y(+)LAT-1 impair the transport function of this complex and cause a selective aminoaciduria, lysinuric protein intolerance (LPI, OMIM #222700), associated with severe, complex clinical symptoms. The subunits of an active transporter co-localize in the plasma membrane, but the exact process of dimerization is unclear since direct evidence for the assembly of this transporter in intact human cells has not been available. In this study, we used fluorescence resonance energy transfer (FRET) microscopy to investigate the interactions of y(+)LAT-1 and 4F2hc in HEK293 cells expressing y(+)LAT-1 and 4F2hc fused with ECFP or EYFP. FRET was quantified by measuring fluorescence intensity changes in the donor fluorophore (ECFP) after the photobleaching of the acceptor (EYFP). Increased donor fluorescence could be detected throughout the cell, from the endoplasmic reticulum and Golgi complex to the plasma membrane. Therefore, our data prove the interaction of y(+)LAT-1 and 4F2hc prior to the plasma membrane and thus provide evidence for 4F2hc functioning as a chaperone in assisting the transport of y(+)LAT-1 to the plasma membrane.

  16. 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)

  17. 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.

  18. L-4F Differentially Alters Plasma Levels of Oxidized Fatty Acids Resulting in more Anti-Inflammatory HDL in Mice

    PubMed Central

    Imaizumi, Satoshi; Grijalva, Victor; Navab, Mohamad; Van Lenten, Brian J.; Wagner, Alan C.; Anantharamaiah, G.M.; Fogelman, Alan M.; Reddy, Srinivasa T.

    2011-01-01

    To determine in vivo if L-4F differentially alters plasma levels of oxidized fatty acids resulting in more anti-inflammatory HDL. Injecting L-4F into apoE null mice resulted in a significant reduction in plasma levels of 15-HETE, 5-HETE, 13-HODE and 9-HODE. In contrast, plasma levels of 20-HETE were not reduced and plasma levels of 14,15-EET, which are derived from the cytochrome P450 pathway, were elevated after injection of L-4F. Injection of 13(S)-HPODE into wild-type C57BL/6J mice caused an increase in plasma levels of 13-HODE and 9-HODE and was accompanied by a significant loss in the anti-inflammatory properties of HDL. The response of atherosclerosis resistant C3H/HeJ mice to injection of 13(S)-HPODE was similar but much more blunted. Injection of L-4F at a site different from that at which the 13(S)-HPODE was injected resulted in significantly lower plasma levels of 13-HODE and 9-HODE and significantly less loss of HDL anti-inflammatory properties in both strains. i) L-4F differentially alters plasma levels of oxidized fatty acids in vivo. ii) The resistance of the C3H/HeJ strain to atherosclerosis may in part be mediated by a reduced reaction of this strain to these potent lipid oxidants. L-4F differentially alters plasma levels of oxidized fatty acids in mice and the resistance of C3H/HeJ mice to atherosclerosis may be mediated by a reduced reaction of this strain to these potent lipid oxidants. PMID:20642447

  19. 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.

  20. CYP4F2 (rs2108622) Gene Polymorphism Association with Age-Related Macular Degeneration

    PubMed Central

    Kriauciuniene, Loresa; Balciuniene, Vilma Jurate; Buteikiene, Dovile; Miniauskiene, Goda; Liutkeviciene, Rasa

    2016-01-01

    Background. Age-related macular degeneration is the leading cause of blindness in elderly individuals where aetiology and pathophysiology of age-related macular degeneration are not absolutely clear. Purpose. To determine the frequency of the genotype of rs2108622 in patients with early and exudative age-related macular degeneration. Methods. The study enrolled 190 patients with early age-related macular degeneration, 181 patients with exudative age-related macular degeneration (eAMD), and a random sample of 210 subjects from the general population (control group). The genotyping of rs2108622 was carried out using the real-time polymerase chain reaction method. Results. The analysis of rs2108622 gene polymorphism did not reveal any differences in the distribution of C/C, C/T, and T/T genotypes between the early AMD group, the eAMD group, and the control group. The CYP4F2 (1347C>T) T/T genotype was more frequent in males with eAMD compared to females (10.2% versus 0.8%; p = 0.0052); also T/T genotype was less frequently present in eAMD females compared to healthy control females (0.8% versus 6.2%; p = 0.027). Conclusion. Rs2108622 gene polymorphism had no predominant effect on the development of early AMD and eAMD. The T/T genotype was more frequent in males with eAMD compared to females and less frequently present in eAMD females compared to healthy females. PMID:27652291

  1. Enlarging the angle of view in Michelson-interferometer-based shearography by embedding a 4f system.

    PubMed

    Wu, Sijin; He, Xiaoyuan; Yang, Lianxiang

    2011-07-20

    Digital shearography based on Michelson interferometers suffers from the disadvantage of a small angle of view due to the structure. We demonstrate a novel digital shearography system with a large angle of view. In the optical arrangement, the imaging lens is in front of the Michelson interferometer rather than behind it as in traditional digital shearography. Thus, the angle of view is no longer limited by the Michelson interferometer. The images transmitting between the separate lens and camera are accomplished by a 4f system in the new style of shearography. The influences of the 4f system on shearography are also discussed.

  2. 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}

  3. Regulation of Pou4f3 Gene Expression in Hair Cells by 5’ DNA in Mice

    PubMed Central

    Masuda, Masatsugu; Dulon, Didier; Pak, Kwang; Mullen, Lina M.; Li, Yan; Erkman, Linda; Ryan, Allen F.

    2011-01-01

    The POU-domain transcription POU4F3 is expressed in the sensory cells of the inner ear. Expression begins shortly after commitment to the hair cell (HC) fate, and continues throughout life. It is required for terminal HC differentiation and survival. To explore regulation of the murine Pou4f3 gene, we linked enhanced green fluorescent protein (eGFP) to 8.5 kb of genomic sequence 5’ to the start codon in transgenic mice. eGFP was uniformly present in all embryonic and neonatal HCs. Expression of eGFP was also observed in developing Merkel cells and olfactory neurons as well as adult inner and vestibular HCs, mimicking the normal expression pattern of POU4F3 protein, with the exception of adult outer HCs. Apparently ectopic expression was observed in developing inner ear neurons. On a Pou4f3 null background, the transgene produced expression in embryonic HCs which faded soon after birth both in vivo and in vitro. Pou4f3 null HCs treated with caspase 3 and 9 inhibitors survived longer than untreated HCs, but still showed reduced expression of eGFP. The results suggest the existence of separate enhancers for different HC types, as well as strong autoregulation of the Pou4f3 gene. Bioinformatic analysis of four divergent mammalian species revealed three highly-conserved regions within the transgene: 400 bp immediately 5’ to the Pou4f3 ATG, a short sequence at -1.3 kb, and a longer region at -8.2 to -8.5 kb. The latter contained E-box motifs that bind bHLH transcription factors, including motifs activated by ATOH1. Co-transfection of HEK293 or VOT-E36 cells with ATOH1 and the transgene as a reporter enhanced eGFP expression when compared to the transgene alone. Chromatin immunoprecipitation of the three highly conserved regions revealed binding of ATOH1 to the distal-most conserved region. The results are consistent with regulation of Pou4f3 in HCs by ATOH1 at a distal enhancer. PMID:21958861

  4. XPS valence characterization of lithium salts as a tool to study electrode/electrolyte interfaces of Li-ion batteries.

    PubMed

    Dedryvère, R; Leroy, S; Martinez, H; Blanchard, F; Lemordant, D; Gonbeau, D

    2006-07-06

    X-ray photoelectron valence spectra of lithium salts LiBF4, LiPF6, LiTFSI, and LiBETI have been recorded and analyzed by means of density functional theory (DFT) calculations, with good agreement between experimental and calculated spectra. The results of this study are used to characterize electrode/electrolyte interfaces of graphite negative electrodes in Li-ion batteries using organic carbonate electrolytes containing LiTFSI or LiBETI salts. By a combined X-ray photoelectron spectroscopy (XPS) core peaks/valence analysis, we identify the main constituents of the interface. Differences in the surface layers' composition can be evidenced, depending on whether LiTFSI or LiBETI is used as the lithium salt.

  5. Electronic structure of Ar+ ion-sputtered thin-film MoS2: A XPS and IPES study

    NASA Astrophysics Data System (ADS)

    Santoni, Antonino; Rondino, Flaminia; Malerba, Claudia; Valentini, Matteo; Mittiga, Alberto

    2017-01-01

    Polycrystalline MoS2 grown by Mo sulphurization was exposed to increasing doses of Ar+ ions at 250 eV starting from 2.2 × 1015 ions/cm2 to 3.92 × 1017 ions/cm2. Electronic structure changes were monitored by X-Ray Photoelectron Spectroscopy (XPS) and Inverse Photolectron Spectroscopy (IPES). No change in the Fermi level position was observed with Ar+ dosing. Ion bombardment resulted in a new visible feature at lower binding energy in the Mo3d core level, while the S2p lineshape showed little changes. The formation of a steady state from 2.49 × 1017 ions/cm2 has been detected. The investigation of the occupied and unoccupied states on the steady-state surface pointed to the simultaneous presence of metallic-like Mo with amorphous MoS2-x.

  6. Oxidation of arsenopyrite and deposition of gold on the oxidized surfaces: A scanning probe microscopy, tunneling spectroscopy and XPS study

    NASA Astrophysics Data System (ADS)

    Mikhlin, Yuri L.; Romanchenko, Alexander S.; Asanov, Igor P.

    2006-10-01

    size has been revealed using STS. This effect along with the increase by 0.2-0.5 eV in the XPS Au 4f binding energies were tentatively ascribed to retarding the electron transitions by emerging electrostatic charge on gold nanoparticles (Coulomb blockade). Possible mechanisms for the effects, and their potential role in the deposition and hydrometallurgy of "invisible" gold are discussed.

  7. 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

  8. 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.

  9. Ferromagnetic versus antiferromagnetic exchange interactions in tetrathiafulvalene-based 3d/4f heterobimetallic complexes.

    PubMed

    Cosquer, Goulven; Pointillart, Fabrice; Le Gal, Yann; Golhen, Stéphane; Cador, Olivier; Ouahab, Lahcène

    2011-10-24

    (TTF-salphen)M compounds (TTF-salphen(2-)=4,5-bis(propylthio)tetrathiafulvalene-N,N'-phenylenebis(salicylideneimine) dianion; M=Cu(II) and Ni(II)) have been treated with Ln(hfac)(3)·2H(2)O precursors (hfac(-)=1,1,1,5,5,5-hexafluoroacetylacetonate anion; Ln=Gd(III), Tb(III), and Dy(III)) to elaborate unprecedented 3d/4f TTF-based heterobimetallic complexes of formula [(TTF-salphen)MLn(hfac)(3)]. All the structures of these compounds have been resolved by X-ray diffraction on single crystals. The structures of these complexes are formed by a TTF-salphen(2-) ligand coordinated to the 3d metal ions in the inert tetradentate N(2)O(2) site. The Ln(hfac)(3) fragment is coordinated to the (TTF-salphen)M one through the two phenolate bridges. Even if the complexes are similar in both Cu(II) and Ni(II) families, the crystal packing is different. In the first case, dimers of TTF-salphen(2-) donors constitute the organic network. In the other case, a reminiscent organic network is observed with S···S contacts. The photophysical properties of [(TTF-salphen)CuDy(hfac)(3)] (3) in chloroform solution highlight the redshift of the TTF→salphen charge transfer (400 cm(-1)) relative to the analogue excitations in (TTF-salphen)Cu, which attest to the stability of these structures in solution. Static magnetic measurements have allowed us to quantify the ferromagnetic interactions (J=+1.29 cm(-1)) between Cu(II) and Gd(III) in the [(TTF-salphen)CuGd(hfac)(3)] complex. Finally, an empirical method that consists of the comparisons of the magnetic properties of [(TTF-salphen)CuTb(hfac)(3)] with [(TTF-salphen)NiTb(hfac)(3)] and [(TTF-salphen)CuDy(hfac)(3)] with [(TTF-salphen)NiDy(hfac)(3)] has established that ferromagnetic interactions take place between Cu(II) and Tb(III) ions, whereas unusual antiferromagnetic interactions have been identified between Cu(II) and Dy(III) ions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. 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

  11. Development of progesterone receptor antagonists from 1,2-dihydrochromeno[3,4-f]quinoline agonist pharmacophore.

    PubMed

    Zhi, Lin; Ringgenberg, Josef D; Edwards, James P; Tegley, Christopher M; West, Sarah J; Pio, Barbara; Motamedi, Mehrnouch; Jones, Todd K; Marschke, Keith B; Mais, Dale E; Schrader, William T

    2003-06-16

    A series of 1,2-dihydrochromeno[3,4-f]quinoline derivatives was synthesized and tested in biological assays to evaluate the nonsteroidal progesterone receptor modulator pharmacophore (4) as antiprogestins. A number of potent analogues were identified by modification of the substituents at the D-ring.

  12. 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.

  13. 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.

  14. 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.

  15. Mutation of the 4F2 heavy-chain carboxy terminus causes y+ LAT2 light-chain dysfunction.

    PubMed

    Chubb, Sarah; Kingsland, Alice L; Bröer, Angelika; Bröer, Stefan

    2006-01-01

    Heteromeric amino acid transporters are composed of two subunits--a multipass membrane protein called the 'light chain'--and a single pass glycoprotein called the 'heavy chain'. The light chain contains the transport pore, while the heavy chain appears to be necessary for trafficking the light chain to the plasma membrane. In this study, the role of the 4F2hc heavy chain in the function of the y+ LAT2 light chain was investigated. Carboxy terminal truncations and site specific mutants of 4F2hc were co-expressed in Xenopus laevis oocytes with the y+ LAT2 light chain, and the oocytes were analysed for transport activity and surface expression. Truncations of the 4F2hc carboxy terminus ranging between 15 and 404 residues caused a complete loss of light chain function, although all heterodimers were expressed at the cell surface. This indicated that the 15 carboxy-terminal residues of 4F2hc are required for the transport function of the heterodimer. Mutation of the conserved residue leucine 523 to glutamine in the carboxy terminus reduced the Vmax of arginine and leucine uptake. The affinity of the transporter for both arginine and leucine remained unaltered, but the Km-value of Na+, being cotransported with leucine, increased about three-fold. The change of the Na+ Km caused a specific defect of leucine efflux, whereas uptake of leucine at high extracellular NaCl concentration was unaffected.

  16. eIF4F is a nexus of resistance to anti-BRAF and anti-MEK cancer therapies.

    PubMed

    Boussemart, Lise; Malka-Mahieu, Hélène; Girault, Isabelle; Allard, Delphine; Hemmingsson, Oskar; Tomasic, Gorana; Thomas, Marina; Basmadjian, Christine; Ribeiro, Nigel; Thuaud, Frédéric; Mateus, Christina; Routier, Emilie; Kamsu-Kom, Nyam; Agoussi, Sandrine; Eggermont, Alexander M; Désaubry, Laurent; Robert, Caroline; Vagner, Stéphan

    2014-09-04

    In BRAF(V600)-mutant tumours, most mechanisms of resistance to drugs that target the BRAF and/or MEK kinases rely on reactivation of the RAS-RAF-MEK-ERK mitogen-activated protein kinase (MAPK) signal transduction pathway, on activation of the alternative, PI(3)K-AKT-mTOR, pathway (which is ERK independent) or on modulation of the caspase-dependent apoptotic cascade. All three pathways converge to regulate the formation of the eIF4F eukaryotic translation initiation complex, which binds to the 7-methylguanylate cap (m(7)G) at the 5' end of messenger RNA, thereby modulating the translation of specific mRNAs. Here we show that the persistent formation of the eIF4F complex, comprising the eIF4E cap-binding protein, the eIF4G scaffolding protein and the eIF4A RNA helicase, is associated with resistance to anti-BRAF, anti-MEK and anti-BRAF plus anti-MEK drug combinations in BRAF(V600)-mutant melanoma, colon and thyroid cancer cell lines. Resistance to treatment and maintenance of eIF4F complex formation is associated with one of three mechanisms: reactivation of MAPK signalling, persistent ERK-independent phosphorylation of the inhibitory eIF4E-binding protein 4EBP1 or increased pro-apoptotic BCL-2-modifying factor (BMF)-dependent degradation of eIF4G. The development of an in situ method to detect the eIF4E-eIF4G interactions shows that eIF4F complex formation is decreased in tumours that respond to anti-BRAF therapy and increased in resistant metastases compared to tumours before treatment. Strikingly, inhibiting the eIF4F complex, either by blocking the eIF4E-eIF4G interaction or by targeting eIF4A, synergizes with inhibiting BRAF(V600) to kill the cancer cells. eIF4F not only appears to be an indicator of both innate and acquired resistance but also is a promising therapeutic target. Combinations of drugs targeting BRAF (and/or MEK) and eIF4F may overcome most of the resistance mechanisms arising in BRAF(V600)-mutant cancers.

  17. 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.

  18. A combined QCM and XPS investigation of asphaltene adsorption on metal surfaces.

    PubMed

    Rudrake, Amit; Karan, Kunal; Horton, J Hugh

    2009-04-01

    To investigate asphaltene-metal interactions, a combined quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS) study of asphaltene adsorption on a gold surface was conducted. Adsorption experiments were conducted at 25 degrees C with solutions of asphaltenes in toluene at concentrations ranging from 50 to 1500 ppm. QCM measurements yielded information on the kinetics of adsorption and further assessment of the data allowed the estimation of equilibrium adsorption levels. XPS analysis of adsorbed and bulk asphaltene demonstrated the presence of carboxylic, thiophenic, sulfide, pyridinic and pyrrolic type functional groups. The intensity of the main carbon (C-H) peak was related to surface coverage of adsorbed asphaltene as a function of asphaltene concentration by a simple mathematical model. The mass adsorption data from the QCM experiments also allowed estimation of the surface coverage, which was compared to those from XPS analyses. Surface coverage estimates as a function of asphaltene concentration could be described by a Langmuir (type-I) isotherm. The free energy of asphaltene adsorption was estimated to be -26.8+/-0.1 and -27.3+/-0.1 kJ/mol from QCM and XPS data, respectively assuming asphaltene molar mass of 750 g/gmol. QCM and XPS data was also analyzed to estimate adsorbed layer thickness after accounting for surface coverage. The thickness of the adsorbed asphaltene estimated from both XPS and QCM data analyses ranged from 6-8 nm over the entire range of adsorption concentrations investigated.

  19. 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

  20. 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

    2015-09-08

    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.

  1. Association of the Cytoplasmic Membrane Protein XpsN with the Outer Membrane Protein XpsD in the Type II Protein Secretion Apparatus of Xanthomonas campestris pv. Campestris

    PubMed Central

    Lee, Hsien-Ming; Wang, Kuan-Cheng; Liu, Yi-Ling; Yew, Hsin-Yan; Chen, Ling-Yun; Leu, Wei-Ming; Chen, David Chanhen; Hu, Nien-Tai

    2000-01-01

    An xps gene cluster composed of 11 open reading frames is required for the type II protein secretion in Xanthomonas campestris pv. campestris. Immediately upstream of the xpsD gene, which encodes an outer membrane protein that serves as the secretion channel by forming multimers, there exists an open reading frame (previously designated ORF2) that could encode a protein of 261 amino acid residues. Its N-terminal hydrophobic region is a likely membrane-anchoring sequence. Antibody raised against this protein could detect in the wild-type strain of X. campestris pv. campestris a protein band with an apparent molecular mass of 36 kDa by Western blotting. Its aberrant slow migration in sodium dodecyl sulfate-polyacrylamide gels might be due to its high proline content. We designated this protein XpsN. By constructing a mutant strain with an in-frame deletion of the chromosomal xpsN gene, we demonstrated that it is required for the secretion of extracellular enzyme by X. campestris pv. campestris. Subcellular fractionation studies indicated that the XpsN protein was tightly associated with the membrane. Sucrose gradient sedimentation followed by immunoblot analysis revealed that it primarily appeared in the cytoplasmic membrane fractions. Immune precipitation experiments indicated that the XpsN protein was coprecipitated with the XpsD protein. In addition, the XpsN protein was co-eluted with the (His)6-tagged XpsD protein from the metal affinity chromatography column. All observations suggested that the XpsN protein forms a stable complex with the XpsD protein. In addition, immune precipitation analysis of the XpsN protein with various truncated XpsD proteins revealed that the C-terminal region of the XpsD protein between residues 650 and 759 was likely to be involved in complex formation between the two. PMID:10692359

  2. Intercalation and grafting of benzene derivatives into zinc-aluminum and copper-chromium layered double hydroxide hosts: an XPS monitoring study.

    PubMed

    Fleutot, Solenne; Dupin, Jean-Charles; Renaudin, G; Martinez, Hervé

    2011-10-21

    We report an original strategy to describe, via X-ray photoelectron spectroscopy (XPS) measurements, the interactions between the organic and the mineral sub-systems within a multifunctional hybrid material. A tunable layered double hydroxide (LDH) host system, either a Zn(2)Al- or Cu(2)Cr-hydrotalcite like compound, is modified with the insertion of the organic guest entities, 4-phenol-sulfonate (HBS) or -carboxylate (HBC). The resulting interactions are studied at two levels: after the organic molecules' insertion in the host LDH (ionic exchange between the LDH counter-ions and the organic anions) and after the condensation (grafting) of the organic species onto the mineral layers when thermally treated. For the inserted material, the main XPS results show a stabilization of the organic molecules within the mineral sheets via H bonding as found elsewhere with FTIR study, the mineral matrix being unchanged. The XPS signal of the organic molecules slightly changes with a widening of core peaks, attesting to some local surrounding modifications. When heating up the Zn(2)Al hybrid material, stronger interactions between organic and inorganic systems appeared from around 80 °C with some obvious electronic changes as monitored with the XPS S2p signal of the HBS guest molecules. At the same time, the PXRD pattern clearly shows a decrease of the basal spacing according to a two step contraction process which could be interpreted as a progressive organic molecule condensation onto the inorganic layers via iono-covalent bonds. A copper-chromium LDH is also studied to probe the same kind of interactions with the HBS molecules. The ability of distortion of such mineral material involves a peculiar process of contraction from 40 °C with the immediate and effective anchorage of organic molecules. This journal is © the Owner Societies 2011

  3. Effects of Ar and O2 additives on SiO2 etching in C4F8-based plasmas

    NASA Astrophysics Data System (ADS)

    Li, Xi; Ling, Li; Hua, Xuefeng; Fukasawa, Masanaga; Oehrlein, Gottlieb S.; Barela, Marcos; Anderson, Harold M.

    2003-01-01

    Gas mixtures based on C4F8 are promising for the development of high-performance SiO2 plasma etching processes. Measurements of important gas phase species, thin film etching rates and surface chemistry changes were performed for inductively coupled plasmas fed with C4F8/Ar and C4F8/O2 gas mixtures. The addition of Ar to C4F8 causes a strong increase of the plasma density relative to that of pure C4F8 (by up to a factor of 4× at 90% Ar). For O2 addition the changes in plasma density are small up to 90% O2 relative to pure C4F8. Infrared laser absorption spectroscopy was used to determine the absolute densities of neutral CF, CF2 and COF2 radical species as a function of the gas composition. The densities of CF and CF2 were enhanced for certain operating conditions when Ar was added to C4F8 as long as the amount of Ar remained below 20%. For instance, the partial pressure of CF was 0.1 mTorr for a 20 mTorr 1400 W source power discharge for pure C4F8, and increased to 0.13 mTorr at 20% Ar. Above 20% Ar it decreased, roughly following the gas dilution. The CF2 partial pressure was about 5 mTorr for the same conditions, and increased by about 10% at 20% Ar. Above 20% Ar the CF2 partial pressure decreased roughly linearly with the amount of Ar added, to about 2 mTorr at 50% Ar. Of particular interest was the analysis of the difference in behavior of CF, CF2 and COF2 partial pressures over SiO2 and Si surfaces, with and without rf bias power (in the latter case a self-bias voltage of -100 V was used). For pure C4F8 discharges at 20 mTorr and 1400 W inductive power without rf bias the partial pressures of CF, CF2 and COF2 radicals are comparable over SiO2 and Si surfaces. Upon applying a rf bias, the CF2 partial pressure over a SiO2 surface is reduced much more strongly than for a Si surface. The overall reduction appears to be consistent with the relative SiO2/Si etch rate ratios observed for these conditions. These results indicate that CF2 is consumed during the

  4. The revised human liver cytochrome P450 "Pie": absolute protein quantification of CYP4F and CYP3A enzymes using targeted quantitative proteomics.

    PubMed

    Michaels, Scott; Wang, Michael Zhuo

    2014-08-01

    The CYP4F subfamily of enzymes has been identified recently to be involved in the metabolism of endogenous compounds (arachidonic acid and leukotriene B4), nutrients (vitamins K1 and E), and xenobiotics (pafuramidine and fingolimod). CYP4F2 and CYP4F3B are reported to be expressed in the human liver. However, absolute concentrations of these enzymes in human liver microsomes (HLMs) and their interindividual variability have yet to be determined because of the lack of specific antibodies. Here, an liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based targeted quantitative proteomic approach was employed to determine the absolute protein concentrations of CYP4F2 and CYP4F3B compared with CYP3A in two panels of HLMs (n = 31). As a result, the human hepatic cytochrome P450 (P450) "pie" has been revised to include the contribution of CYP4F enzymes, which amounts to 15% of the total hepatic cytochrome P450 enzymes. CYP4F3B displayed low interindividual variability (3.3-fold) in the HLM panels whereas CYP4F2 displayed large variability (21-fold). However, CYP4F2 variability decreased to 3.4-fold if the two donors with the lowest expression were excluded. In contrast, CYP3A exhibited 29-fold interindividual variability in the same HLM panels. The proposed marker reaction for CYP4F enzymes pafuramidine/DB289 M1 formation did not correlate with CYP4F protein content, suggesting alternate metabolic pathways for DB289 M1 formation in HLMs. In conclusion, CYP4F enzymes are highly expressed in the human liver and their physiologic and pharmacologic roles warrant further investigation.

  5. BDNF gene therapy induces auditory nerve survival and fiber sprouting in deaf Pou4f3 mutant mice.

    PubMed

    Fukui, H; Wong, H T; Beyer, L A; Case, B G; Swiderski, D L; Di Polo, A; Ryan, A F; Raphael, Y

    2012-01-01

    Current therapy for patients with hereditary absence of cochlear hair cells, who have severe or profound deafness, is restricted to cochlear implantation, a procedure that requires survival of the auditory nerve. Mouse mutations that serve as models for genetic deafness can be utilized for developing and enhancing therapies for hereditary deafness. A mouse with Pou4f3 loss of function has no hair cells and a subsequent, progressive degeneration of auditory neurons. Here we tested the influence of neurotrophin gene therapy on auditory nerve survival and peripheral sprouting in Pou4f3 mouse ears. BDNF gene transfer enhanced preservation of auditory neurons compared to control ears, in which nearly all neurons degenerated. Surviving neurons in treated ears exhibited pronounced sprouting of nerve fibers into the auditory epithelium, despite the absence of hair cells. This enhanced nerve survival and regenerative sprouting may improve the outcome of cochlear implant therapy in patients with hereditary deafness.

  6. k Dependence of the crystal-field splittings of 4f states in rare-earth systems.

    PubMed

    Vyalikh, D V; Danzenbächer, S; Kucherenko, Yu; Kummer, K; Krellner, C; Geibel, C; Holder, M G; Kim, T K; Laubschat, C; Shi, M; Patthey, L; Follath, R; Molodtsov, S L

    2010-12-03

    The occupation, energy separation, and order of the crystal-field-split 4f states are crucial for the understanding of the magnetic properties of rare-earth systems. We provide the experimental evidence that crystal-field-split 4f states exhibit energy dispersion in momentum space leading to variations of energy spacings between them and even of their energy sequence across the Brillouin zone. These observations were made by performing angle-resolved photoemission experiments on YbRh(2)Si(2) and properly simulated within a simple model based on results obtained by inelastic neutron scattering experiments and band structure calculations. Our findings should be generally applicable to rare-earth systems and have considerable impact on the understanding of magnetism and related phenomena.

  7. [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.

  8. Apolipoprotein A-I mimetic peptide 4F rescues pulmonary hypertension by inducing microRNA-193-3p.

    PubMed

    Sharma, Salil; Umar, Soban; Potus, Francois; Iorga, Andrea; Wong, Gabriel; Meriwether, David; Breuils-Bonnet, Sandra; Mai, Denise; Navab, Kaveh; Ross, David; Navab, Mohamad; Provencher, Steeve; Fogelman, Alan M; Bonnet, Sébastien; Reddy, Srinivasa T; Eghbali, Mansoureh

    2014-08-26

    Pulmonary arterial hypertension is a chronic lung disease associated with severe pulmonary vascular changes. A pathogenic role of oxidized lipids such as hydroxyeicosatetraenoic and hydroxyoctadecadienoic acids is well established in vascular disease. Apolipoprotein A-I mimetic peptides, including 4F, have been reported to reduce levels of these oxidized lipids and improve vascular disease. However, the role of oxidized lipids in the progression of pulmonary arterial hypertension and the therapeutic action of 4F in pulmonary arterial hypertension are not well established. We studied 2 different rodent models of pulmonary hypertension (PH): a monocrotaline rat model and a hypoxia mouse model. Plasma levels of hydroxyeicosatetraenoic and hydroxyoctadecadienoic acids were significantly elevated in PH. 4F treatment reduced these levels and rescued preexisting PH in both models. MicroRNA analysis revealed that microRNA-193-3p (miR193) was significantly downregulated in the lung tissue and serum from both patients with pulmonary arterial hypertension and rodents with PH. In vivo miR193 overexpression in the lungs rescued preexisting PH and resulted in downregulation of lipoxygenases and insulin-like growth factor-1 receptor. 4F restored PH-induced miR193 expression via transcription factor retinoid X receptor α. These studies establish the importance of microRNAs as downstream effectors of an apolipoprotein A-I mimetic peptide in the rescue of PH and suggest that treatment with apolipoprotein A-I mimetic peptides or miR193 may have therapeutic value. © 2014 American Heart Association, Inc.

  9. ApoA-I Mimetic Peptide 4F Rescues Pulmonary Hypertension by Inducing MicroRNA-193-3p

    PubMed Central

    Sharma, Salil; Umar, Soban; Potus, Francois; Iorga, Andrea; Wong, Gabriel; Meriwether, David; Breuils-Bonnet, Sandra; Mai, Denise; Navab, Kaveh; Ross, David; Navab, Mohamad; Provencher, Steeve; Fogelman, Alan M.; Bonnet, Sébastien; Reddy, Srinivasa T.; Eghbali, Mansoureh

    2014-01-01

    Background Pulmonary Arterial Hypertension (PAH) is a chronic lung disease associated with severe pulmonary vascular changes. A pathogenic role of oxidized lipids such as hydroxyeicosatetraenoic acids (HETEs) and hydroxyoctadecadienoic acids (HODEs) is well established in vascular disease. Apolipoprotein A-I (apoA-I) mimetic peptides including 4F have been reported to reduce levels of these oxidized lipids and improve vascular disease. However, the role of oxidized lipids in the progression of PAH and the therapeutic action of 4F in PAH is not well established. Methods and Results We studied two different rodent models of Pulmonary Hypertension (PH); a monocrotaline (MCT) rat model and a hypoxia mouse model. Plasma levels of HETEs and HODEs were significantly elevated in PH. 4F treatment reduced these levels and rescued pre-existing PH in both models. MicroRNA analysis revealed that miR193-3p (miR193) was significantly downregulated in the lung tissue and in serum from both PAH patients and in PH rodents. In-vivo miR193 overexpression in the lungs rescued pre-existing PH and resulted in downregulation of lipoxygenases and insulin-like growth factor-1 receptor. 4F restored PH-induced miR193 expression via transcription factor retinoid X receptor alpha (RXRα). Conclusions These studies establish the importance of microRNAs as downstream effectors of an apoA-I mimetic peptide in the rescue of PH and suggest that treatment with apoA-I mimetic peptides, or miR193 may have therapeutic value. PMID:24963038

  10. 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.

  11. 5-benzylidene-1,2-dihydrochromeno[3,4-f]quinolines as selective progesterone receptor modulators.

    PubMed

    Zhi, Lin; Tegley, Christopher M; Pio, Barbara; Edwards, James P; Motamedi, Mehrnouch; Jones, Todd K; Marschke, Keith B; Mais, Dale E; Risek, Boris; Schrader, William T

    2003-09-11

    A series of 5-benylidene-1,2-dihydrochromeno[3,4-f]quinolines (4) were synthesized and tested in bioassays to evaluate their progestational activities, receptor- and tissue-selectivity profiles as selective progesterone receptor modulators (SPRMs). Most of the new analogues exhibited as highly potent progestins with more than 100-fold receptor selectivity over other steroid hormone receptors and LG120920 (7b) demonstrated tissue selectivity toward uterus and vagina versus breasts in a rodent model after oral administration.

  12. 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.

  13. Arginine transport in human erythroid cells: discrimination of CAT1 and 4F2hc/y+LAT2 roles.

    PubMed

    Rotoli, Bianca Maria; Closs, Ellen I; Barilli, Amelia; Visigalli, Rossana; Simon, Alexandra; Habermeier, Alice; Bianchi, Nicoletta; Gambari, Roberto; Gazzola, Gian C; Bussolati, Ovidio; Dall'Asta, Valeria

    2009-10-01

    Since arginine metabolites, such as nitric oxide and polyamines, influence the expression of genes involved in erythroid differentiation, the transport of the cationic amino acid may play an important role in erythroid cells. However, available data only concern the presence in these cells of CAT1 transporter (system y(+)), while no information exists on the role of the heterodimeric transporters of system y(+)L (4F2hc/y(+)LAT1 and 4F2hc/y(+)LAT2) which operates transmembrane arginine fluxes cis-inhibited by neutral amino acids in the presence of sodium. Using erythroleukemia K562 cells and normal erythroid precursors, we demonstrate here that arginine transport in human erythroid cells is due to the additive contributions of a leucine-sensitive and leucine-insensitive component. In both cell types, leucine inhibition of arginine influx is much less evident in the absence of sodium, a hallmark of system y(+)L. In K562 cells, N-ethylmaleimide, a known inhibitor of CAT transporters (system y(+)), suppresses only a fraction of arginine influx corresponding to leucine-insensitive uptake. Moreover, in Xenopus oocytes coexpressing 4F2hc and y(+)LAT2, leucine exerts a marked inhibition of arginine transport, partially dependent on sodium, while no inhibition is seen in oocytes expressing CAT1. Lastly, silencing of SLC7A6, the gene for y(+)LAT2, lowers arginine transport and doubles the intracellular content of the cationic amino acid in K562 cells. We conclude that arginine transport in human erythroid cells is due to both system y(+) (CAT1 transporter) and system y(+)L (4F2hc/y(+)LAT2 isoform), which mainly contribute, respectively, to the influx and to the efflux of the cationic amino acid.

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

    PubMed

    Kumari, Sudesh; Roudjane, Mourad; Hewage, Dilrukshi; Liu, Yang; Yang, Dong-Sheng

    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 Møller-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.

  15. 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.

  16. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    NASA Astrophysics Data System (ADS)

    Baltrusaitis, Jonas; Mendoza-Sanchez, Beatriz; Fernandez, Vincent; Veenstra, Rick; Dukstiene, Nijole; Roberts, Adam; Fairley, Neal

    2015-01-01

    Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  18. 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.

  19. CYP4F2 repression and a modified alpha-tocopherol (vitamin E) metabolism are two independent consequences of ethanol toxicity in human hepatocytes.

    PubMed

    Russo, A; Bartolini, D; Torquato, P; Giusepponi, D; Barola, C; Galarini, R; Birringer, M; Lorkowski, S; Galli, F

    2017-04-01

    The expression of CYP4F2, a form of cytochrome P-450 with proposed role in α-tocopherol and long-chain fatty acid metabolism, was explored in HepG2 and HepaRG human hepatocytes during ethanol toxicity. Cytotoxicity, ROS production, and JNK and ERK1/2 kinase signaling increased in a dose and time-dependent manner during ethanol treatments; CYP4F2 gene expression decreased, while other CYP4F forms, namely 4F11 and 12, increased along with 3A4 and 2E1 isoforms. α-Tocopherol antagonized the cytotoxicity and CYP4F2 gene repression effect of ethanol in HepG2 cells. Ethanol stimulated the tocopherol-ω-hydroxylase activity and the other steps of vitamin E metabolism, which points to a minor role of CYP4F2 in this metabolism of human hepatocytes. PPAR-γ and SREBP-1c followed the same expression pattern of CYP4F2 in response to ethanol and α-tocopherol treatments. Moreover, the pharmacological inhibition of PPAR-γ synergized with ethanol in decreasing CYP4F2 protein expression, which suggests a role of this nuclear receptor in CYP4F2 transcriptional regulation. In conclusion, ethanol toxicity modifies the CYP expression pattern of human hepatic cells impairing CYP4F2 transcription and protein expression. These changes were associated with a lowered expression of the fatty acid biosynthesis regulators PPAR-γ and SREBP-1c, and with an increased enzymatic catabolism of vitamin E. CYP4F2 gene repression and a sustained vitamin E metabolism appear to be independent effects of ethanol toxicity in human hepatocytes. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    DOE PAGES

    Myhre, Kristian; Burns, Jonathan; Meyer, Harry; ...

    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.

  1. Comparing XPS and ToF-ERDA measurement of high-k dielectric materials

    NASA Astrophysics Data System (ADS)

    Martin, D. M.; Enlund, J.; Kappertz, O.; Jensen, J.

    2008-03-01

    Compositional analysis of aluminium oxy-nitride (AlON) films deposited by reactive magnetron sputtering was performed using time-of-flight elastic recoil detection analysis (ToF-ERDA) and X-ray photoelectron spectroscopy (XPS) with sputter profiling. The composition profiles of the films depend on deposition conditions. The benefits of the different analytical methods are discussed and comparison of the profiles is performed. Conversion of the depth scale from XPS sputter time to a nm scale is implemented and the ToF-ERDA profile fitted. Densities of the deposited AlON films are calculated indicating differing film quality in agreement with the composition profile extracted.

  2. Surface Characterization of Polymer Blends by XPS and ToF-SIMS

    PubMed Central

    Chan, Chi Ming; Weng, Lu-Tao

    2016-01-01

    The surface properties of polymer blends are important for many industrial applications. The physical and chemical properties at the surface of polymer blends can be drastically different from those in the bulk due to the surface segregation of the low surface energy component. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary mass spectrometry (ToF-SIMS) have been widely used to characterize surface and bulk properties. This review provides a brief introduction to the principles of XPS and ToF-SIMS and their application to the study of the surface physical and chemical properties of polymer blends. PMID:28773777

  3. Investigating early stages of biocorrosion with XPS: AISI 304 stainless steel exposed to Burkholderia species

    NASA Astrophysics Data System (ADS)

    Johansson, Leena-Sisko; Saastamoinen, Tuomas

    1999-04-01

    We have investigated the interactions of an exopolymer-producing bacteria, Burkholderia sp. with polished AISI 304 stainless steel substrates using X-ray photoelectron spectroscopy (XPS). Steel coupons were exposed to the pure bacteria culture in a specially designed flowcell for 6 h during which the experiment was monitored in situ with an optical microscope. XPS results verified the formation of biofilm containing extracellular polymer on all the samples exposed to bacteria. Sputter results indicated that some ions needed for metabolic processes were trapped within the biofilm. Changes in the relative Fe concentration and Fe 2p peak shape indicated that also iron had accumulated into the biofilm.

  4. Variation in Genes Controlling Warfarin Disposition and Response in American Indian and Alaska Native People: CYP2C9, VKORC1, CYP4F2, CYP4F11, GGCX

    PubMed Central

    Yracheta, Joseph; Dillard, Denise A.; Schilling, Brian; Khan, Burhan; Hopkins, Scarlett; Boyer, Bert; Black, Jynene; Wiener, Howard; Tiwari, Hemant K.; Gordon, Adam; Nickerson, Deborah; Tsai, Jesse M.; Farin, Federico M.; Thornton, Timothy A.; Rettie, Allan E.; Thummel, Kenneth E.

    2015-01-01

    Objectives Pharmacogenetic testing is projected to improve health outcomes and reduce the cost of care by increasing therapeutic efficacy and minimizing drug toxicity. American Indian and Alaska Native (AI/AN) people historically have been excluded from pharmacogenetic research and its potential benefits, a deficiency we sought to address. The vitamin K antagonist warfarin is prescribed for prevention of thromboembolic events, although its narrow therapeutic index and wide inter-individual variability necessitate close monitoring of drug response. Therefore, we were interested in variation in CYP2C9, VKORC1, CYP4F2, CYP4F11, and GGCX, which encode enzymes important for the activity of warfarin and synthesis of vitamin K dependent blood clotting factors. Methods We resequenced these genes in 188 AI/AN people in partnership with Southcentral Foundation (SCF) in Anchorage, AK and 94 Yup'ik people living in the Yukon-Kuskokwim Delta of southwest Alaska to identify known or novel function-disrupting variation. We conducted genotyping for specific SNPs in larger cohorts of each study population (380 and 350, respectively). Results We identified high frequencies of the lower-warfarin dose VKORC1 haplotype (−1639G>A and 1173C>T) and the higher-warfarin dose CYP4F2*3 variant. We also identified two relatively common, novel, and potentially function-disrupting variants in CYP2C9 (M1L and N218I), which, along with CYP2C9*3, CYP2C9*2 and CYP2C9*29, predict that a significant proportion of AI/AN people will have decreased CYP2C9 activity. Conclusions Overall, we predict a lower average warfarin dose requirement in AI/AN populations in Alaska than that seen in non-AI/AN populations of the US, a finding consistent with clinical experience in Alaska. PMID:25946405

  5. 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.

  6. XPS investigations of Pt and Rh supported on γ-Al 2O 3 and TiO 2

    NASA Astrophysics Data System (ADS)

    Huizinga, T.; van'T Blik, H. F. J.; Vis, J. C.; Prins, R.

    1983-12-01

    An XPS investigation of Pt and Rh supported on γ-Al 2O 3 and TiO 2 was performed in order to establish the differences in metal-support interactions. The binding energies of the core levels of the supported metal particles were found to vary as a function of the dispersion of the supported metal, with the highest binding energy for the highest dispersion. This binding energy variation is caused by differences in the extra-atomic relaxation of metal particles of different sizes. In small particles there is a less effective screening of the core holes created during photoemission. For Pt/TiO 2 catalysts prereduced below 1015 K, slightly higher binding energies were found than for Pt/Al 2O 3 catalysts after comparable pretreatments. No differences in binding energies could be observed between Rh/TiO 2 and Rh/Al 2O 3 over a wide range of dispersions. In situ reduction of M/TiO 2 at 523 or 823 K led to essentially the same biding energy. These results show that there is no significant electron transfer from Ti 3+ to metallic platinum or rhodium. Consequently the strongly reduced chemisorption properties of metals on TiO 2, observed after high temperature reduction (SMSI), cannot be due to negatively charged metal atoms. For M/TiO 2 samples prereduced above 1015 K, an increase in binding energy of the metal core levels is found in combination with a decrease in dispersion of the metal. This behaviour is explained by encapsulation and spalling of the metal particles during an observed anatase-to-rutile phase transformation.

  7. Synthesis and bioevaluation of [18F]4-fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG): a novel radiotracer for quantitative PET studies of cardiac sympathetic innervation

    PubMed Central

    Jang, Keun Sam; Jung, Yong-Woon; Sherman, Phillip S.; Quesada, Carole A.; Gu, Guie; Raffel, David M.

    2013-01-01

    A new cardiac sympathetic nerve imaging agent, [18F]4-fluoro-m-hydroxyphenethylguanidine ([18F]4F-MHPG), was synthesized and evaluated. The radiosynthetic intermediate [18F]4-fluoro-m-tyramine ([18F]4F-MTA) was prepared and then sequentially reacted with cyanogen bromide and NH4Br/NH4OH to afford [18F]4F-MHPG. Initial bioevaluations of [18F]4F-MHPG (biodistribution studies in rats and kinetic studies in the isolated rat heart) were similar to results previously reported for the carbon-11 labeled analog [11C]4F-MHPG. The neuronal uptake rate of [18F]4F-MHPG into the isolated rat heart was 0.68 ml/min/g wet and its retention time in sympathetic neurons was very long (T1/2 > 13 h). A PET imaging study in a nonhuman primate with [18F]4F-MHPG provided high quality images of the heart, with heart-to-blood ratios at 80–90 min after injection of 5-to-1. These initial kinetic and imaging studies of [18F]4F-MHPG suggest that this radiotracer may allow for more accurate quantification of regional cardiac sympathetic nerve density than is currently possible with existing neuronal imaging agents. PMID:23416009

  8. D-4F, an apolipoprotein A-I mimetic, inhibits TGF-β1 induced epithelial-mesenchymal transition in human alveolar epithelial cell.

    PubMed

    You, Jia; Wang, Jintao; Xie, Linshen; Zhu, Chengwen; Xiong, Jingyuan

    2016-10-01

    Emerging evidences support that transforming growth factor β1 (TGF-β1) induced epithelial-mesenchymal transition (EMT) participates in the pathogenesis of pulmonary fibrosis and asthmatic airway remodeling. Recent studies demonstrated that apolipoprotein A-I (Apo A-I) is the only known substance that can resolve established pulmonary fibrotic nodules, and Apo A-I mimetic D-4F (a synthetic polypeptide consisting of 18 amino acids) plays an inhibitory role in murine asthmatic model. However, cellular mechanisms for such therapeutic effects of Apo A-I and D-4F remain to be elucidated. This study evaluated the effects of D-4F on TGF-β1 induced EMT in human type II alveolar epithelial cell line A549. A549 cells treated with 10ng/ml of TGF-β1 manifested distinct EMT, including fibroblastic morphological changes, down-regulation of epithelial marker E-cadherin and up-regulation of mesenchymal marker vimentin. These EMT related changes were all inhibited by D-4F in a concentration dependent manner. Transcriptional investigation demonstrated clearly that D-4F dose-dependently compensated for the reduced E-cadherin mRNA level and the increased vimentin mRNA level in TGF-β1 treated A549 cells. Translational analysis revealed that D-4F significantly reversed the TGF-β1 induced changes of E-cadherin and vimentin levels. These results suggested that D-4F inhibits TGF-β1 induced EMT in human alveolar epithelial cell. Given the functional similarities between D-4F and Apo A-I, it is speculated that D-4F and Apo A-I are able to exert possible anti-fibrotic and anti-asthmatic effects via inhibiting alveolar EMT, and D-4F may possess beneficial clinical potential for patients suffering from pulmonary fibrosis and asthma. Copyright © 2016 Elsevier GmbH. All rights reserved.

  9. CYP4F2 Is a Vitamin K1 Oxidase: An Explanation for Altered Warfarin Dose in Carriers of the V433M Variant

    PubMed Central

    McDonald, Matthew G.; Rieder, Mark J.; Nakano, Mariko; Hsia, Clara K.; Rettie, Allan E.

    2009-01-01

    Genetic polymorphisms in VKORC1 and CYP2C9, genes controlling vitamin K1 (VK1) epoxide reduction and (S)-warfarin metabolism, respectively, are major contributors to interindividual variability in warfarin dose. The V433M polymorphism (rs2108622) in CYP4F2 has also been associated with warfarin dose and speculatively linked to altered VK1 metabolism. Therefore, the purpose of the present study was to determine the role of CYP4F2 and the V433M polymorphism in the metabolism of VK1 by human liver. In vitro metabolic experiments with accompanying liquid chromatography-tandem mass spectrometry analysis demonstrated that recombinant CYP4F2 (Supersomes) and human liver microsomes supplemented with NADPH converted VK1 to a single product. A screen of all commercially available P450 Supersomes showed that only CYP4F2 was capable of metabolizing VK1 to this product. Steady-state kinetic analysis with recombinant CYP4F2 and with human liver microsomes revealed a substrate Km of 8 to 10 μM. Moreover, anti-CYP4F2 IgG, as well as several CYP4F2-selective chemical inhibitors, substantially attenuated the microsomal reaction. Finally, human liver microsomes genotyped for rs2108622 demonstrated reduced vitamin K1 oxidation and lower CYP4F2 protein concentrations in carriers of the 433M minor allele. These data demonstrate that CYP4F2 is a vitamin K1 oxidase and that carriers of the CYP4F2 V433M allele have a reduced capacity to metabolize VK1, secondary to an rs2108622-dependent decrease in steady-state hepatic concentrations of the enzyme. Therefore, patients with the rs2108622 polymorphism are likely to have elevated hepatic levels of VK1, necessitating a higher warfarin dose to elicit the same anticoagulant response. PMID:19297519

  10. 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.

  11. Kinetics and its accompanying thermodynamics studies on simultaneous complexation of heterobimetallic neodymium (III) with zinc (II) and L-tryptophan in aquated DMF using 4f-4f absorption spectra.

    PubMed

    Huidrom, Bimola; Singh, N Rajmuhon

    2014-01-24

    The 4f-4f absorption spectra of the simultaneous heterobimetallic complexation of trivalent neodymium ion with l-tryptophan and divalent zinc ion in aquated DMF (50%, v/v) at pH 6.0 was recorded at the time interval of 1h. From the observed absorption spectra, the values of intensity parameters such as oscillator strength (P) and Judd-Ofelt intensity (Tλ) parameters, kinetics and thermodynamics parameters were evaluated. The rate constant increases with an increase in the temperature along with the oscillator strengths and Judd-Ofelt intensity parameters. The positive values of the change in the standard enthalpy (ΔH°) and entropy (ΔS°) indicate that the complexation is endothermic. The negative values of the change in the standard free energy (ΔG°) in the range from 293.15 K to 308.15 K, indicate that the reaction occurs spontaneously and hence the formation of heterobimetallic complex in the solution is favored kinetically and thermodynamically.

  12. 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

    2015-09-08

    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.

  13. Two nanosized 3d-4f clusters featuring four Ln6 octahedra encapsulating a Zn4 tetrahedron.

    PubMed

    Zheng, Xiu-Ying; Wang, Shi-Qiang; Tang, Wen; Zhuang, Gui-Lin; Kong, Xiang-Jian; Ren, Yan-Ping; Long, La-Sheng; Zheng, Lan-Sun

    2015-07-07

    Two high-nuclearity 3d-4f clusters Ln24Zn4 (Ln = Gd and Sm) featuring four Ln6 octahedra encapsulating a Zn4 tetrahedron were obtained through the self-assembly of Zn(OAc)2 and Ln(ClO4)3. Quantum Monte Carlo (QMC) simulations show the antiferromagnetic coupling between Gd(3+) ions. Studies of the magnetocaloric effect (MCE) show that the Gd24Zn4 cluster exhibits the entropy change (-ΔSm) of 31.4 J kg(-1) K(-1).

  14. Nonlinear characterization of materials using the D4σ method inside a Z-scan 4f-system.

    PubMed

    Boudebs, Georges; Besse, Valentin; Cassagne, Christophe; Leblond, Hervé; de Araújo, Cid B

    2013-07-01

    We show that direct measurement of the beam radius in Z-scan experiments using a CCD camera at the output of a 4f-imaging system allows higher sensitivity and better accuracy than Baryscan. One of the advantages is to be insensitive to pointing instability of pulsed lasers because no hard (physical) aperture is employed as in the usual Z-scan. In addition, the numerical calculations involved here and the measurement of the beam radius are simplified since we do not measure the transmittance through an aperture and it is not subject to mathematical artifacts related to a normalization process, especially when the diffracted light intensity is very low.

  15. The heterodimeric amino acid transporter 4F2hc/y+LAT2 mediates arginine efflux in exchange with glutamine.

    PubMed Central

    Bröer, A; Wagner, C A; Lang, F; Bröer, S

    2000-01-01

    The cationic amino acid arginine, due to its positive charge, is usually accumulated in the cytosol. Nevertheless, arginine has to be released by a number of cell types, e.g. kidney cells, which supply other organs with this amino acid, or the endothelial cells of the blood-brain barrier which release arginine into the brain. Arginine release in mammalian cells can be mediated by two different transporters, y(+)LAT1 and y(+)LAT2. For insertion into the plasma membrane, these transporters have to be associated with the type-II membrane glycoprotein 4F2hc [Torrents, Estevez, Pineda, Fernandez, Lloberas, Shi, Zorzano and Palacin (1998) J. Biol. Chem. 273, 32437-32445]. The present study elucidates the function and distribution of y(+)LAT2. In contrast to y(+)LAT1, which is expressed mainly in kidney epithelial cells, lung and leucocytes, y(+)LAT2 has a wider tissue distribution, including brain, heart, testis, kidney, small intestine and parotis. When co-expressed with 4F2hc in Xenopus laevis oocytes, y(+)LAT2 mediated uptake of arginine, leucine and glutamine. Arginine uptake was inhibited strongly by lysine, glutamate, leucine, glutamine, methionine and histidine. Mutual inhibition was observed when leucine or glutamine was used as substrate. Inhibition of arginine uptake by neutral amino acids depended on the presence of Na(+), which is a hallmark of y(+)LAT-type transporters. Although arginine transport was inhibited strongly by glutamate, this anionic amino acid was only weakly transported by 4F2hc/y(+)LAT2. Amino acid transport via 4F2hc/y(+)LAT2 followed an antiport mechanism similar to the other members of this new family. Only preloaded arginine could be released in exchange for extracellular amino acids, whereas marginal release of glutamine or leucine was observed under identical conditions. These results indicated that arginine has the highest affinity for the intracellular binding site and that arginine release may be the main physiological function of

  16. The heterodimeric amino acid transporter 4F2hc/y+LAT2 mediates arginine efflux in exchange with glutamine.

    PubMed

    Bröer, A; Wagner, C A; Lang, F; Bröer, S

    2000-08-01

    The cationic amino acid arginine, due to its positive charge, is usually accumulated in the cytosol. Nevertheless, arginine has to be released by a number of cell types, e.g. kidney cells, which supply other organs with this amino acid, or the endothelial cells of the blood-brain barrier which release arginine into the brain. Arginine release in mammalian cells can be mediated by two different transporters, y(+)LAT1 and y(+)LAT2. For insertion into the plasma membrane, these transporters have to be associated with the type-II membrane glycoprotein 4F2hc [Torrents, Estevez, Pineda, Fernandez, Lloberas, Shi, Zorzano and Palacin (1998) J. Biol. Chem. 273, 32437-32445]. The present study elucidates the function and distribution of y(+)LAT2. In contrast to y(+)LAT1, which is expressed mainly in kidney epithelial cells, lung and leucocytes, y(+)LAT2 has a wider tissue distribution, including brain, heart, testis, kidney, small intestine and parotis. When co-expressed with 4F2hc in Xenopus laevis oocytes, y(+)LAT2 mediated uptake of arginine, leucine and glutamine. Arginine uptake was inhibited strongly by lysine, glutamate, leucine, glutamine, methionine and histidine. Mutual inhibition was observed when leucine or glutamine was used as substrate. Inhibition of arginine uptake by neutral amino acids depended on the presence of Na(+), which is a hallmark of y(+)LAT-type transporters. Although arginine transport was inhibited strongly by glutamate, this anionic amino acid was only weakly transported by 4F2hc/y(+)LAT2. Amino acid transport via 4F2hc/y(+)LAT2 followed an antiport mechanism similar to the other members of this new family. Only preloaded arginine could be released in exchange for extracellular amino acids, whereas marginal release of glutamine or leucine was observed under identical conditions. These results indicated that arginine has the highest affinity for the intracellular binding site and that arginine release may be the main physiological function of

  17. Electron Scattering Processes from Plasma Processing Gases: CF3I, C3F8 and C4F8

    NASA Astrophysics Data System (ADS)

    Kimura, Mineo

    2000-10-01

    Brief review of the current level of understanding of electron scattering processes from plasma processing gases such as CF3I, C3F8 and C4F8 will be presented. Experimental as well as theoretical studies for these gases have been carried out last a few years by several groups, and although the amount of cross-section data is still far from sufficient, we are able to establish the data set for some processes in these gases. I will briefly discuss possible next-generation processing gases.

  18. Simulation of XPS C1s spectra of organic monolayers by quantum chemical methods.

    PubMed

    Giesbers, Marcel; Marcelis, Antonius T M; Zuilhof, Han

    2013-04-16

    Several simple methods are presented and evaluated to simulate the X-ray photoelectron spectra (XPS) of organic monolayers and polymeric layers by density functional theory (DFT) and second-order Møller-Plesset theory (MP2) in combination with a series of basis sets. The simulated carbon (C1s) XPS spectra as obtained via B3LYP/6-311G(d,p) or M11/6-311G(d,p) calculations are in good agreement (average mean error <0.3 eV) with the experimental spectra, and good estimates of C1s spectra can be obtained via E(C1s)(exp) = 0.9698EC1s(theory) + 20.34 (in eV) (B3LYP/6-311G(d,p)). As a result, the simulated C1s XPS spectra can elucidate the binding energies of the different carbon species within an organic layer and, in this way, greatly aid the assignment of complicated C1s XPS spectra. The paper gives a wide range of examples, including haloalkanes, esters, (thio-)ethers, leaving groups, clickable functionalities, and bioactive moieties.

  19. En route to traceable reference standards for surface group quantifications by XPS, NMR and fluorescence spectroscopy.

    PubMed

    Hennig, Andreas; Dietrich, Paul M; Hemmann, Felix; Thiele, Thomas; Borcherding, Heike; Hoffmann, Angelika; Schedler, Uwe; Jäger, Christian; Resch-Genger, Ute; Unger, Wolfgang E S

    2015-03-21

    The fluorine content of polymer particles labelled with 2,2,2-trifluoroethylamine was reliably quantified with overlapping sensitivity ranges by XPS and solid-state NMR. This provides a first step towards reference materials for the metrological traceability of surface group quantifications. The extension of this concept to fluorescence spectroscopy is illustrated.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Design and synthesis of thiazolo[5,4-f]quinazolines as DYRK1A inhibitors, part II.

    PubMed

    Foucourt, Alicia; Hédou, Damien; Dubouilh-Benard, Carole; Girard, Angélique; Taverne, Thierry; Casagrande, Anne-Sophie; Désiré, Laurent; Leblond, Bertrand; Besson, Thierry

    2014-09-26

    The convenient synthesis of a focused library (forty molecules) of novel 6,6,5-tricyclic thiazolo[5,4-f]quinazolines was realized mainly under microwave irradiation. A novel 6-aminobenzo[d]thiazole-2,7-dicarbonitrile (1) was used as a versatile molecular platform for the synthesis of various derivatives. Kinase inhibition, of the obtained final compounds, was evaluated on a panel of two kinases (DYRK1A/1B) together with some known reference DYRK1A and DYRK1B inhibitors (harmine, TG003, NCGC-00189310 and leucettine L41). Compound IC50 values were obtained and compared. Five of the novel thiazolo[5,4-f]quinazoline derivatives prepared, EHT 5372 (8c), EHT 6840 (8h), EHT 1610 (8i), EHT 9851 (8k) and EHT 3356 (9b) displayed single-digit nanomolar or subnanomolar IC50 values and are among the most potent DYRK1A/1B inhibitors disclosed to date. DYRK1A/1B kinases are known to be involved in the regulation of various molecular pathways associated with oncology, neurodegenerative diseases (such as Alzheimer disease, AD, or other tauopathies), genetic diseases (such as Down Syndrome, DS), as well as diseases involved in abnormal pre-mRNA splicing. The compounds described in this communication constitute a highly potent set of novel molecular probes to evaluate the biology/pharmacology of DYR1A/1B in such diseases.

  6. Environmental Dependence of Artifact CD Peaks of Chiral Schiff Base 3d-4f Complexes in Soft Mater PMMA Matrix

    PubMed Central

    Okamoto, Yu; Nidaira, Keisuke; Akitsu, Takashiro

    2011-01-01

    Four chiral Schiff base binuclear 3d-4f complexes (NdNi, NdCu, GdNi, and GdCu) have been prepared and characterized by means of electronic and CD spectra, IR spectra, magnetic measurements, and X-ray crystallography (NdNi). A so-called artifact peak of solid state CD spectra, which was characteristic of oriented molecules without free molecular rotation, appeared at about 470 nm. Magnetic data of the complexes in the solid state (powder) and in PMMA cast films or solutions indicated that only GdCu preserved molecular structures in various matrixes of soft maters. For the first time, we have used the changes of intensity of artifact CD peaks to detect properties of environmental (media solid state (KBr pellets), PMMA cast films, concentration dependence of PMMA in acetone solutions, and pure acetone solution) for chiral 3d-4f complexes (GdCu). Rigid matrix keeping anisotropic orientation exhibited a decrease in the intensity of the artifact CD peak toward negative values. The present results suggest that solid state artifact CD peaks can be affected by environmental viscosity of a soft mater matrix. PMID:22072930

  7. 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

  8. 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.

  9. 4F-PBP (4'-fluoro-α-pyrrolidinobutyrophenone), a new substance of abuse: Structural characterization and purity NMR profiling.

    PubMed

    Gaspar, Helena; Bronze, Soraia; Ciríaco, Sara; Queirós, Cláudio Rafael; Matias, Ana; Rodrigues, João; Oliveira, Cristina; Cordeiro, Carlos; Santos, Susana

    2015-07-01

    The rapidly growing problem of new psychoactive substances (NPS) makes the time management for international control a real challenge, with the traditional detection methods becoming increasingly inadequate. NPS screening technologies, such as NMR, which allows multiple substances to be detected, characterized and quantified simultaneously from a single sample, offers a rapid solution to this problem. This study describes the application of NMR to the simultaneous detection, characterization and quantification of samples of white powders seized by the Portuguese Police. 4F-PBP (4'-fluoro-α-pyrolidinobutyrophenone) a new synthetic psychoactive cathinone cut with myo-inositol was found in two seized products. The structural characterization of 4F-PBP was elucidated in the mixture, and confirmed after isolation from the matrix by (1)H, (13)C, (19)F NMR and MS. Myo-inositol was found for the first time as a cutting agent of cathinones. Furthermore another seized product was characterized as being MDPBP, with a high degree of purity, and its spectroscopic elucidation enabled the correction of (13)C NMR literature assignments.

  10. General equation for size nanocharacterization of the core-shell nanoparticles by X-ray photoelectron spectroscopy.

    PubMed

    Gillet, Jean-Numa; Meunier, Michel

    2005-05-12

    Nanocharacterization is essential for nanoengineering of new types of core-shell (c-s) nanoparticles, which can be used to design new devices for photonics, electronics, catalysis, medicine, etc. X-ray photoelectron spectroscopy (XPS) has been widely used to study the elemental composition of the c-s nanoparticles. However, the physical and chemical properties of a c-s nanoparticle dramatically depend on the sizes of its core and shell. We therefore propose a general equation for the XPS intensity of a c-s nanoparticle, which is based on an analytical model. With this equation, XPS can now also be used for nanocharacterization of the core and shell sizes of the c-s nanoparticles (with a diameter smaller than or equal to the XPS probing depth of approximately 10 nm). To validate the new equation with experimental XPS data, we first determine the average shell thickness of a group of c-s nanoparticles by comparing the XPS intensity of reference bare cores to that of the c-s nanoparticles. Then we study the growth kinetics of the cores and shells of another group of c-s nanoparticles where the shells are obtained by oxidation.

  11. 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.

  12. Enhancement by LDL of transfer of L-4F and oxidized lipids to HDL in C57BL/6J mice and human plasma.

    PubMed

    Meriwether, David; Imaizumi, Satoshi; Grijalva, Victor; Hough, Greg; Vakili, Ladan; Anantharamaiah, G M; Farias-Eisner, Robin; Navab, Mohamad; Fogelman, Alan M; Reddy, Srinivasa T; Shechter, Ishaiahu

    2011-10-01

    The apoA-I mimetic peptide L-4F [(Ac-D-W-F-K-A-F-Y-D-K-V-A-E-K-F-K-E-A-F-NH2) synthesized from all L-amino acids] has shown potential for the treatment of a variety of diseases. Here, we demonstrate that LDL promotes association between L-4F and HDL. A 2- to 3-fold greater association of L-4F with human HDL was observed in the presence of human LDL as compared with HDL by itself. This association further increased when LDL was supplemented with the oxidized lipid 15S-hydroxy-5Z, 8Z, 11Z, 13E-eicosatetraenoic acid (15HETE). Additionally, L-4F significantly (P = 0.02) promoted the transfer of 15HETE from LDL to HDL. The transfer of L-4F from LDL to HDL was demonstrated both in vitro and in C57BL/6J mice. L-4F, injected into C57BL/6J mice, associated rapidly with HDL and was then cleared quickly from the circulation. Similarly, L-4F loaded onto human HDL and injected into C57BL/6J mice was cleared quickly with T(1/2) = 23.6 min. This was accompanied by a decline in human apoA-I with little or no effect on the mouse apoA-I. Based on these results, we propose that i) LDL promotes the association of L-4F with HDL and ii) in the presence of L-4F, oxidized lipids in LDL are rapidly transferred to HDL allowing these oxidized lipids to be acted upon by HDL-associated enzymes and/or cleared from the circulation.

  13. Sol-gel synthesis of Li2CoPO4F/C nanocomposite as a high power cathode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wu, Xiaobiao; Gong, Zhengliang; Tan, Shi; Yang, Yong

    2012-12-01

    Li2CoPO4F cathode materials are successfully synthesized by solid state (SS) and sol-gel (SG) methods. The XRD results show that Li2CoPO4F samples prepared by two methods are both indexed as orthorhombic structure with space group Pnma. The particles of Li2CoPO4F (SS) are micron grade. However, the particle of Li2CoPO4F (SG) is only tens of nanometers with an amorphous carbon uniformly coated. A high reversible capacity of 138 mAh g-1 is achieved for Li2CoPO4F/C (SG) at 1 C, which is much higher than that of 106 mAh g-1 prepared by solid state method. Also, Li2CoPO4F/C (SG) shows excellent rate performance, a capacity of 119 mAh g-1, 86% retention of that at 1 C, is achieved at 20 C. The excellent rate capacity of the material is attributed to nanosized particles and uniform carbon coating that reduce ion diffusion length and enhance electronic conductivity. Furthermore, the preliminary performance characteristics of Li2CoPO4F/Li4Ti5O12 full cells are presented. The cell shows a high voltage plateau around 3.4 V with excellent rate capacity. The impressive electrochemical properties indicate that Li2CoPO4F can be a promising high power cathode material for lithium ion batteries. The capacity fading mechanism of Li2CoPO4F is also briefly investigated.

  14. Status of the O. alpha. calculation of e sup + e sup - yields W sup + W sup - yields 4f(gamma)

    SciTech Connect

    Aeppli, A.

    1991-11-01

    We consider the full process e{sup +}e{sup {minus}} {yields} W{sup +}W{sup {minus}} {yields} 4f. We show that the off-shell effect are sizable and comparable to radiative effects. We give the exact results for hard bremsstrahlung processes e{sup +}e{sup {minus}} {yields} (4f + {gamma}) and the results of the O({alpha}) improved cross sections for e{sup +}e{sup {minus}} {yields} W{sup +}W{sup {minus}} including photon radiation. The status of the virtual corrections to the 4f-process is described.

  15. Status of the O{alpha} calculation of e{sup +}e{sup -} {yields} W{sup +}W{sup -} {yields} 4f(gamma)

    SciTech Connect

    Aeppli, A.

    1991-11-01

    We consider the full process e{sup +}e{sup {minus}} {yields} W{sup +}W{sup {minus}} {yields} 4f. We show that the off-shell effect are sizable and comparable to radiative effects. We give the exact results for hard bremsstrahlung processes e{sup +}e{sup {minus}} {yields} (4f + {gamma}) and the results of the O({alpha}) improved cross sections for e{sup +}e{sup {minus}} {yields} W{sup +}W{sup {minus}} including photon radiation. The status of the virtual corrections to the 4f-process is described.

  16. Immunochemical quantification of cynomolgus CYP2J2, CYP4A and CYP4F enzymes in liver and small intestine.

    PubMed

    Uehara, Shotaro; Murayama, Norie; Nakanishi, Yasuharu; Nakamura, Chika; Hashizume, Takanori; Zeldin, Darryl C; Yamazaki, Hiroshi; Uno, Yasuhiro

    2015-02-01

    1. An increasing number of studies have indicated the roles of CYP4 proteins in drug metabolism; however, CYP4 expression has not been measured in cynomolgus monkeys, an important animal species for drug metabolism studies. 2. In this study, cynomolgus CYP4A11, CYP4F2/3, CYP4F11 and CYP4F12, along with CYP2J2, were immunoquantified using selective antibodies in 28 livers and 35 small intestines, and their content was compared with CYP1A, CYP2A, CYP2B6, CYP2C9/19, CYP2D, CYP2E1, CYP3A4 and CYP3A5, previously quantified. 3. In livers, CYP2J2, CYP4A11, CYP4F2/3, CYP4F11 and CYP4F12, varied 1.3- to 4.3-fold, represented 11.2, 14.4, 8.0, 2.7 and 0.3% of total immunoquantified CYP1-4 proteins, respectively. 4. In small intestines, CYP2J2, CYP4F2/3, CYP4F11 and CYP4F12, varied 2.4- to 9.7-fold, represented 6.9, 36.4, 2.4 and 9.3% of total immunoquantified CYP1-4 proteins, respectively, making CYP4F the most abundant P450 subfamily in small intestines. CYP4A11 was under the detection limit in all of the samples analyzed. 5. Significant correlations were found in liver for CYP4A11 with lauric acid 11-/12-hydroxylation and for CYP4F2/3 and CYP4F11 with astemizole hydroxylation. 6. This study revealed the relatively abundant contents of cynomolgus CYP2J2, CYP4A11 and CYP4Fs in liver and/or small intestine, suggesting their potential roles for the metabolism of xenobitotics and endogenous substrates.

  17. Optical absorption and NMR spectroscopic studies on paramagnetic neodymium(III) complexes with beta-diketone and heterocyclic amines. The environment effect on 4f-4f hypersensitive transitions.

    PubMed

    Ansari, A A; Irfanullah, M; Iftikhar, K

    2007-08-01

    The optical absorption spectra of [Nd(acac)3(H2O)2].H2O, [Nd(acac)3bpy] and [Nd(acac)3phen(H2O)2] (where acac=acetylacetone, bpy=2,2'-bipyridyl and phen=1,10-phenanthroline) complexes in the visible region, in a series of non-aqueous solvents (methanol, ethanol, isopropanol, chloroform, acetonitrile, pyridine, nitrobenzene and dimethylsulphoxide) have been analyzed. The transition 4G(5/2)<--4I(9/2) (Nd-VI) located near the middle of the visible region (17,500 cm(-1)) is hypersensitive. Its behavior is in sharp contrast to many other typically weak and consistently unvaried, normal 4f-4f transitions. The oscillator strength of this transition for the chelate as well as its adducts with phen and bpy in any of the solvent employed is larger than the oscillator strength of Nd3+ aqua-ion. It is most intense in pyridine for all the complexes studied and, therefore, pyridine is the most effective in promoting f-f spectral intensity. The band shape and oscillator strength of the hypersensitive transitions display pronounced changes as compared to Nd3+ aqua-ion. The band shapes of the hypersensitive transitions show remarkable changes on passing from aqueous solution to various non-aqueous solutions, which is the result of change in the environment about the Nd(III) ion in the various solutions and suggests change in the environment about the Nd(III) ion in the various solutions and suggests coordination of solvent molecule(s), in some cases. A comparative account of hypersensitivity in the present complexes with those of other adducts of Nd(beta-diketoenolate)3 with heterocyclic amines is discussed. The NMR signals of heterocyclic amines have been shifted to high fields while the resonances due to acetylacetone moiety have moved to low fields. The paramagnetic shift in the complexes is dipolar in nature.

  18. 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.

  19. Cloning and expression of a b(0,+)-like amino acid transporter functioning as a heterodimer with 4F2hc instead of rBAT. A new candidate gene for cystinuria.

    PubMed

    Rajan, D P; Kekuda, R; Huang, W; Wang, H; Devoe, L D; Leibach, F H; Prasad, P D; Ganapathy, V

    1999-10-08

    We have cloned a transporter protein from rabbit small intestine, which, when coexpressed with the 4F2 heavy chain (4F2hc) in mammalian cells, induces a b(0,+)-like amino acid transport activity. This protein (4F2-lc6 for the sixth member of the 4F2 light chain family) consists of 487 amino acids and has 12 putative transmembrane domains. At the level of amino acid sequence, 4F2-lc6 shows significant homology (44% identity) to the other five known members of the 4F2 light chain family, namely LAT1 (4F2-lc1), y(+)LAT1 (4F2-lc2), y(+)LAT2 (4F2-lc3), xCT (4F2-lc4), and LAT2 (4F2-lc5). The 4F2hc/4F2-lc6 complex-mediated transport process is Na(+)-independent and exhibits high affinity for neutral and cationic amino acids and cystine. These characteristics are similar to those of the b(0,+)-like amino acid transport activity previously shown to be associated with rBAT (protein related to b(0,+) amino acid transport system). However, the newly cloned 4F2-lc6 does not interact with rBAT. This is the first report of the existence of a b(0,+)-like amino acid transport process that is independent of rBAT. 4F2-lc6 is expressed predominantly in the small intestine and kidney. Based on the characteristics of the transport process mediated by the 4F2hc/4F2-lc6 complex and the expression pattern of 4F2-lc6 in mammalian tissues, we suggest that 4F2-lc6 is a new candidate gene for cystinuria.

  20. Investigation on the sulfur state and phase transformation of spent and regenerated S zorb sorbents using XPS and XRD

    NASA Astrophysics Data System (ADS)

    Qiu, Limei; Zou, Kang; Xu, Guangtong

    2013-02-01

    A series of industrial S zorb sorbents extracted from production line were characterized by XPS and XRD. The formation of ZnAl2O4 and Zn2SiO4 is the major reason for the deactivation of spent sorbent. The stability of the Zn-containing spinel species leads to the decrease of the desulfurization efficiency of regenerated sorbent. The chemical states of sulfur atom were examined by XPS. The depth distribution of sulfur species and the reductive behavior of sulfate in H2 atmosphere were explored using Ar+ etching XPS and in situ XPS. The formation of sulfate species in the regeneration process decreases the content of ZnO in the surface significantly and should be avoided. XPS and XRD are excellent tools to follow the sulfur chemical states and phase evolution of S zorb sorbent, respectively, which provide important information for the investigation of deactivation pathways and regenerated mechanisms for S zorb sorbent.

  1. A novel reconfigurable optical interconnect architecture using an Opto-VLSI processor and a 4-f imaging system.

    PubMed

    Shen, Mingya; Xiao, Feng; Alameh, Kamal

    2009-12-07

    A novel reconfigurable optical interconnect architecture for on-board high-speed data transmission is proposed and experimentally demonstrated. The interconnect architecture is based on the use of an Opto-VLSI processor in conjunction with a 4-f imaging system to achieve reconfigurable chip-to-chip or board-to-board data communications. By reconfiguring the phase hologram of an Opto-VLSI processor, optical data generated by a vertical Cavity Surface Emitting Laser (VCSEL) associated to a chip (or a board) is arbitrarily steered to the photodetector associated to another chip (or another board). Experimental results show that the optical interconnect losses range from 5.8dB to 9.6dB, and that the maximum crosstalk level is below -36dB. The proposed architecture is tested for high-speed data transmission, and measured eye diagrams display good eye opening for data rate of up to 10Gb/s.

  2. Magnetic Circular Dichroism of X-Ray Emission for Gadolinium in 4d-4f Excitation Region

    NASA Astrophysics Data System (ADS)

    Takayama, Yasuhiro; Shinoda, Motoki; Obu, Kenji; Lee, Chol; Shiozawa, Hidetsugu; Hirose, Masaaki; Ishii, Hiroyoshi; Miyahara, Tsuneaki; Okamoto, Jun

    2002-01-01

    We have measured magnetic circular dichroism of x-ray emission spectra (XES) for gadolinium in the 4d-4f excitation region. At a pre-threshold excitation energy, a large magnetic circular dichroism (MCD) signal appeared in a Raman scattering and the dramatic dependence of the MCD spectra on the excitation energy was observed. Theoretical calculation shows that the magnetic moment estimated with total photoelectron yield (TEY) spectra was much smaller than that with the emission spectra. This indicates that the MCD for the TEY reflects the magnetic state on the surface whereas the MCD for the XES reflects that in the bulk. We also observed the MCD spectra for total photon yield (TPY) and found the great difference of the MCD spectra for the TEY and TPY.

  3. Shock wave studies of the pyrolysis of fluorocarbon oxygenates. II. The thermal dissociation of C4F8O.

    PubMed

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

    2017-01-25

    The thermal decomposition of octafluorooxalane, C4F8O, to C2F4 + CF2 + COF2 has been studied in shock waves highly diluted in Ar between 1300 and 2200 K. The primary dissociation was shown to be followed by secondary dissociation of C2F4 and dimerization of CF2. The primary dissociation was found to be in its falloff range and falloff curves were constructed. The limiting low and high pressure rate constants were estimated and compared with modelling results. Quantum-chemical calculations identified possible reaction pathways, either leading directly to the final products of the reaction or passing through an open-chain CF2CF2CF2 intermediate which dissociates in a second step.

  4. Luminescence in Li2Sr2Al2PO4F9:Dy3+ - a novel nanophosphor.

    PubMed

    Shinde, K N; Dhoble, S J

    2012-01-01

    Earlier research has revealed numerous advantages of the wet chemical method in reaction acceleration, yield improvement, enhanced photoluminescence properties and the evolution of new material phases. In the present study the novel nanophosphor Li(2)Sr(2)Al(2)PO(4)F(9):Dy(3+) was synthesized by a one-step wet chemical method. Formation of single-phase compounds was confirmed by X-ray diffraction (XRD) and characterized by photoluminescence (PL) and transmission electron microscopy (TEM) techniques. The average diameter of the particles was calculated from the TEM image as ca. 20 nm. The synthesized nanophosphor exhibited intense blue and yellow emissions at 482 and 575 nm, respectively, owing to the Dy(3+) ion, by Hg-free excitation at 387 nm, i.e. solid-state lighting excitation. The results obtained showed that phosphors have the potential for applications in the lamp industry.

  5. Evaluation of NH4F/H2O2 effectiveness as a surface passivation agent for Cd1-xZnxTe crystals

    NASA Astrophysics Data System (ADS)

    Wright, Gomez W.; James, Ralph B.; Chinn, Douglas; Brunett, Bruce A.; Olsen, Richard W.; Van Scyoc, John M., III; Clift, W. Miles; Burger, Arnold; Chattopadhyay, Kaushik; Shi, Detang T.; Wingfield, Robert C.

    2000-11-01

    Various passivating agents that reduce the surface leakage current of CZT crystals have been previously reported. In none of the studies, NH4F/H2O2 was identified as a promising passivation agent for CZT. We now present a study that includes the effect of NH4F/H2O2 treatment on the surface properties and detector performance. An elemental depth profile was obtained via Auger Electron Spectroscopy. Furthermore, X-ray Photoelectron Spectroscopy acquired at different processing times to identify the chemical states of the elemental species that composed the dielectric layer. It was found that the NH4F/H2O2 surface passivation significantly improved the sensitivity and energy resolution of CZT detectors. Furthermore, the NH4F/H2O2 treatment did not attack the Au electrodes, which eliminated the need to protect the contacts in the detector fabrication process.

  6. 17 CFR 41.3 - Application for an exemptive order pursuant to section 4f(a)(4)(B) of the Act.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., 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...

  7. 17 CFR 41.3 - Application for an exemptive order pursuant to section 4f(a)(4)(B) of the Act.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., 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...

  8. 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...

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., 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. Atomic layer etching of silicon dioxide using alternating C4F8 and energetic Ar+ plasma beams

    NASA Astrophysics Data System (ADS)

    Kaler, Sanbir S.; Lou, Qiaowei; Donnelly, Vincent M.; Economou, Demetre J.

    2017-06-01

    Atomic layer etching (ALE) of SiO2 was studied by alternating exposure of a 5 nm-thick SiO2 film on Si substrate to (1) a plasma beam emanating from a c-C4F8 inductively coupled plasma (ICP), to grow a fluorocarbon (FC) film composed mainly of CF2, and (2) an energetic (130 eV) Ar+ ion beam extracted from a separate Ar ICP. In situ x-ray photoelectron spectroscopy was used to analyze the chemical composition of the near-surface region, and to quantify the thickness of the FC and SiO2 films. A very thin (3-6 Å), near self-limiting thickness CF2-rich FC film was found to deposit on the SiO2 surface with exposure to continuous or pulsed power C4F8 plasma beams, under conditions that generated a large relative flux of CF2. Following this, a FC film of similar composition grew at ~10 times slower rate. Exposure of the thin film to the Ar+ beam led to removal of 1.9 Å SiO2. An estimated yield of 1.3 SiO2 molecules-per-Ar+ was found for a single ALE step. The rate of 1.9 Å/cycle persisted over multiple ALE cycles, but a carbon-rich residual film did build up. This film can be removed by a brief exposure to an O2-containing plasma beam.

  11. New Pt/Alumina model catalysts for STM and in situ XPS studies

    NASA Astrophysics Data System (ADS)

    Nartova, Anna V.; Gharachorlou, Amir; Bukhtiyarov, Andrey V.; Kvon, Ren I.; Bukhtiyarov, Valerii I.

    2017-04-01

    The new Pt/alumina model catalysts for STM and in situ XPS studies based on thin alumina film formed over the conductive substrate are proposed. Procedure of platinum deposition developed for porous alumina was adapted for the model alumina support. The set of Pt/AlOx-film samples with the different mean platinum particle size was prepared. Capabilities of in situ XPS investigations of the proposed catalysts were demonstrated in study of NO decomposition on platinum nanoparticles. It is shown that proposed model catalysts behave similarly to Pt/γ-Al2O3 and provide the new opportunities for the instrumental studies of platinum catalysts due to resolving several issues (charging, heating, screening) that are typical for the investigation of the porous oxide supported catalysts.

  12. RBS, ERDA and XPS study of Ag and Cu diffusion in PET and PI polymer foils

    NASA Astrophysics Data System (ADS)

    Macková, Anna; Peřina, Vratislav; Švorčík, Václav; Zemek, Josef

    2005-10-01

    Diffusion of Ag and Cu atoms in polyethyleneterephtalate (PET) and polyimide (PI) was studied using Rutherford backscattering spectroscopy (RBS) and elastic recoil detection analysis (ERDA). The samples were prepared by deposition of Ag and Cu thin layers on polymer surface using CVD and diode sputtering techniques. Samples were annealed at temperatures up to 240 °C. X-ray Photoelectron Spectroscopy (XPS) was used for determination of metal-polymer interaction and chemical state of atoms on metal-polymer interface. Faster diffusion of Ag atoms was observed from non-compact Ag layers prepared by diode sputtering than from those prepared by CVD technique. Ag atoms show higher mobility in PET in comparison with PI. XPS measurement gives an evidence of Ag clustering in Ag-PET samples prepared by cathode sputtering. In PI the Cu atoms exhibit higher diffusivity than Ag atoms due to their lower atomic radius.

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

    SciTech Connect

    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.

  14. 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.

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

    SciTech Connect

    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.

  16. 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.

  17. Angular resolved XPS applied to V 2O 5-based catalysts

    NASA Astrophysics Data System (ADS)

    Devriendt, K.; Poelman, H.; Fiermans, L.; Creten, G.; Froment, G. F.

    1996-05-01

    Two applications of angular dependent XPS (X-ray photoelectron spectroscopy) experiments, performed with a Perkin Elmer Phi 5500 ESCA system in the framework of a monolayer catalyst research project, are illustrated. XPFS (X-ray photoelectron forward scattering) measurements were used to show the oxygen removal at the surface of catalytically reduced V 2O 5(001) pellets, in comparison with pure V 2O 5. ARXPS (angle resolved XPS) polar scans were taken from a model catalyst system (TiO 2 anatase supported V 2O 5 layers) in order to determine their components and the chemical state of the system. With the use of the statistical technique MLCFA (maximum likelihood common factor analysis), different overlapping components in the V and Ti photoemission peaks were separated, pointing towards the existence of a VTiO bonding at the {V2O5}/{TiO2} interface.

  18. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Isolation and structural characterization of the human 4F2 heavy-chain gene, an inducible gene involved in T-lymphocyte activation.

    PubMed Central

    Gottesdiener, K M; Karpinski, B A; Lindsten, T; Strominger, J L; Jones, N H; Thompson, C B; Leiden, J M

    1988-01-01

    The human 4F2 cell surface antigen is a 120-kilodalton (kDa) disulfide-linked heterodimer which is composed of an 80- to 90-kDa glycosylated heavy chain (4F2HC) and a 35- to 40-kDa nonglycosylated light chain (4F2LC). 4F2 belongs to a family of inducible cell surface molecules which are involved in T-lymphocyte activation and growth. To better understand the molecular mechanism(s) that controls 4F2HC gene expression in both resting and activated T cells, a 4F2HC human genomic clone was isolated and structurally characterized. The 4F2HC gene spans 8 kilobases of chromosome 11 and is composed of nine exons. The 5' upstream region of the gene displays several properties which are characteristic of housekeeping genes. It is G+C rich and hypomethylated in peripheral blood lymphocyte DNA and contains multiple binding sites for the Sp1 transcription factor while lacking TATA or CCAAT sequences. This region of the gene also displays sequence homologies with several other inducible T-cell genes, including the interleukin-2, interleukin-2 receptor alpha chain, dihydrofolate reductase, thymidine kinase, and transferrin receptor genes. A 255-base-pair fragment of the 4F2HC gene which contains 154 base pairs of the 5' flanking sequence was able to efficiently promote expression of the bacterial chloramphenicol acetyltransferase gene in human Jurkat T cells, indicating that it contains promoter or enhancer (or both) sequences. Analyses of chromatin structure in resting and lectin-activated T cells revealed the presence of stable DNase I-hypersensitive sites within both the 5' flanking and intron 1 regions of the 4F2HC gene. Although the 4F2HC gene displayed many of the structural features characteristic of a constitutively expressed gene, lectin-mediated activation of resting peripheral blood T lymphocytes resulted in a dramatic increase in steady-state levels of 4F2HC mRNA. Images PMID:3265470

  20. An X-Ray Photoelectron Spectroscopy (XPS) Study of Activated Carbons Impregnated with some Organocopper Complexes,

    DTIC Science & Technology

    1993-10-01

    AD-A282 721 l lllllll a Dfene Defence nationals AN X.RAY PHOTOELECTRON SPECTROSCOPY (XPS) STUDY OF ACTIVATED CARBONS IMPREGNATED WITH SOME... ammoniacal solution as a carrier into which all impregnants (except TEDA) were dissolved. Without a suitable carrier, and with the inherent low vapor...and will not be repeated here. All five complexes were synthesized at DREO using known methods. 2 2.2 IMPREGNATING PROCEDURES Two impregnating

  1. 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.

  2. XPS and EDX study on an RuKL zeolite hydrogenation catalyst

    NASA Astrophysics Data System (ADS)

    Liu, You Ying; Zhao, Weijun; Zhang, Shuji; Fang, Yanquan

    Among several zeolite catalysts, synthesized in our laboratories, for hydrogenation reactions, an RuKL zeolite catalyst appeared to be the best. The activity of this RuKL catalyst remained nearly constant after several hydrogenation cycles. To understand the nature of the catalyst XPS and EDX have been applied. According to the analytical results the active components in the catalyst are Ru 3+ and Ru 0.

  3. Soft electronic structure modulation of surface (thin-film) and bulk (ceramics) morphologies of TiO2-host by Pb-implantation: XPS-and-DFT characterization

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Gavrilov, N. V.; Zatsepin, A. F.; Shur, V. Ya.; Esin, A. A.; Kim, S. S.; Kurmaev, E. Z.

    2017-04-01

    The results of combined experimental and theoretical study of substitutional and clustering effects in the structure of Pb-doped TiO2-hosts (bulk ceramics and thin-film morphologies) are presented. Pb-doping of the bulk and thin-film titanium dioxide was made with the help of pulsed ion-implantation without posterior tempering (Electronic Structure Modulation Mode). The X-ray photoelectron spectroscopy (XPS) qualification of core-levels and valence bands and Density-Functional Theory (DFT) calculations were employed in order to study the yielded electronic structure of Pb-ion modulated TiO2 host-matrices. The combined XPS-and-DFT analysis has agreed definitely with the scenario of the implantation stimulated appearance of PbO-like structures in the bulk morphology of TiO2:Pb, whereas in thin-film morphology the PbO2-like structure becomes dominating, essentially contributing weak O/Pb bonding (PbxOy defect clusters). The crucial role of the oxygen hollow-type vacancies for the process of Pb-impurity "insertion" into the structure of bulk TiO2 was pointed out employing DFT-based theoretical background. Both experiment and theory established clearly the final electronic structure re-arrangement of the bulk and thin-film morphologies of TiO2 because of the Pb-modulated deformation and shift of the initial Valence Base-Band Width about 1 eV up.

  4. Combined DFT and XPS investigation of iodine anions adsorption on the sulfur terminated (001) chalcopyrite surface

    NASA Astrophysics Data System (ADS)

    Li, Kui; Zhao, Yaolin; Zhang, Peng; He, Chaohui; Deng, Jia; Ding, Shujiang; Shi, Weiqun

    2016-12-01

    The adsorption of iodine anions (iodide and iodate) on the sulfur terminated (001) chalcopyrite surface has been systematically investigated combining first-principles calculations based on density functional theory (DFT) with X-ray photoelectron spectroscopy (XPS) measurements. Based on the total energy calculations and geometric optimization, the thermodynamically preferred site was copper atom for iodide adsorption and iron atom for iodate adsorption, respectively. In the case of Cu site mode, the iodate underwent a dissociative adsorption, where one Isbnd O bond of iodate ion was broken and the dissociative oxygen atom adsorbed on the adjacent sulphur site. Projected density of states (PDOS) analysis further clarified the interaction mechanism between active sites of chalcopyrite surface and adsorbates. In addition, full-range XPS spectra qualitatively revealed the presence of iodine on chalcopyrite surface. High resolution XPS spectra of the I 3d peaks after adsorption verified the chemical environment of iodine. The binding energies of 618.8 eV and 623.5 eV for I 3d5/2 peaks unveiled that the adsorption of iodide and iodate ions on copper-iron sulfide minerals was the result of formation of low solubility metal iodides precipitate. Also two I 3d peaks with low intensity around 618 eV and 630 eV might be related to the inorganic reduction of iodate to iodide by reducing S2- ion of chalcopyrite.

  5. The Effect of Thermal and Mechanical Treatments on Kaolinite: Characterization by XPS and IEP Measurements.

    PubMed

    Torres Sánchez RM; Basaldella; Marco

    1999-07-15

    The surface transformations induced on kaolinite by different thermal and mechanical treatments have been investigated by means of X-ray photoelectron spectroscopy (XPS), Bremsstrahlung induced Auger spectroscopy, and isoelectric point (IEP) measurements. Heating the kaolinite at temperatures between 500 and 750 degrees C results in the change of a substantial fraction of surface Al from octahedral to tetrahedral coordination, which we associate with the dehydroxylation of kaolinite. Heating at 900 and 980 degrees C brings about the development of an octahedral Al fraction which is associated with the formation of gamma-Al(2)O(3). The development of an Al tetrahedral component in the Al KLL spectra of the mechanically treated (ground) samples has been also observed. The Si/Al atomic ratio obtained by XPS in the thermally treated samples is the same as that shown by the original kaolinite. However, the XPS data show a clear reduction of the Si/Al atomic ratio in the mechanically treated samples, which suggests that the mechanical treatment has induced an Al enrichment of the kaolinite surface. The IEP values indicated a thermal transformation to metakaolinite and mullite with the increase of temperature (750 to 980 degrees C). The IEP change for the milled samples can be only explained by assuming a 30% kaolinite coating by the Al oxide neoformed by grinding. Copyright 1999 Academic Press.

  6. Reduction of copper oxides by UV radiation and atomic hydrogen studied by XPS

    NASA Astrophysics Data System (ADS)

    Fleisch, T. H.; Mains, G. J.

    The reduction of polycrystalline cupric oxide (CuO) and cuprous oxide (Cu 2O) by UV irradiation and by atomic hydrogen was investigated with X-ray photoelectron spectroscopy (XPS or ESCA). UV photons from a low pressure mercury lamp(λ=2537A, hv=4.8cV) slowly reduce both CuO and Cu 2O at room temperature. After approximately 10 h of irradiation the sample surfaces appear completely reduced to metallic Cu. This indicates that after that time the top 30 A of the sample pellets, the approximate sampling depth of XPS, have been reduced. Further irradiation causes the reduction to progress through the pellet interior and bulk phase. The sample color changes from dark to metallic copper. Photochemically generated hydrogen atoms reduce copper oxides at ambient temperatures. The reduction rate is about 10 times faster than the one caused by UV light alone. The reduction of Cu 2O is in both cases slightly slower than the one of CuO. The degree of reduction has been calculated from XPS data in different ways involving the atomic ratio of O/Cu, the relative intensity of the shake-up structure of CuO, and changes in the structure of the Cu L 3M 45M 45 Auger line. Freshly reduced Cu surfaces are sensitive to air exposure. They oxidize easily to Cu 2O.

  7. Organic adlayer on inorganic materials: XPS analysis selectivity to cope with adventitious contamination

    NASA Astrophysics Data System (ADS)

    Landoulsi, Jessem; Genet, Michel J.; Fleith, Sandrine; Touré, Yetioman; Liascukiene, Irma; Méthivier, Christophe; Rouxhet, Paul G.

    2016-10-01

    This work addresses the ubiquitous presence of organic contaminants at inorganic solid surfaces and the improvement of XPS analysis selectivity to cope with it. Water contact angle measurements showed that the adsorption of organic contaminants occurs readily in ambient air, and faster and more extensively under high vacuum. It is stronger on stainless steel (SS) compared to silica and is significantly reduced when SS is sterilized by autoclaving. The reliability of XPS data was evaluated (selectivity, precision, accuracy) by correlations between spectral data incorporating a large amount of results obtained with different XPS spectrometers on SS and glass samples cleaned in different ways and conditioned with several biomacromolecules. The methodology used allows a discrimination to be made between contaminants and deliberately adsorbed biomacromolecules, and offers perspectives for tracking the source of contamination. Furthermore, a discrimination can be made between oxygen from the organic adlayer and oxygen from the substrate, and the O 1s component above 532.0 eV observed for SS is shown to be due to organic contaminants rather than adsorbed water. This approach offers new perspectives to examine the interactions (displacement or not) between contaminants and compounds of interest, e.g. proteins, at the stage of the adsorption process.

  8. XPS and optical studies of Xe +-implanted and annealed YSZ single crystals

    NASA Astrophysics Data System (ADS)

    Xiang, X.; Zu, X. T.; Zhu, S.; Zhang, C. F.; Wang, Z. G.; Wang, L. M.; Ewing, R. C.

    2006-09-01

    Xe + ion implantation with 200 keV was completed at room temperature up to a fluence of 1 × 10 17 ion/cm 2 in yttria-stabilized zirconia (YSZ) single crystals. Optical absorption and X-ray photoelectron spectroscopy (XPS) were used to characterize the changes of optical properties and charge state in the as-implanted and annealed crystals. A broad absorption band centered at 522 or 497 nm was observed in the optical absorption spectra of samples implanted with fluences of 1 × 10 16 ion/cm 2 and 1 × 10 17 ion/cm 2, respectively. These two absorption bands both disappeared due to recombination of color centers after annealing at 250 °C. XPS measurements showed two Gaussian components of O 1s spectrum assigned to and , respectively, in YSZ single crystals. After ion implantation, these two peaks merged into a single peak with the increasing etching depth. However, this single peak split into two Gaussian components again after annealing at 250 °C. The concentration of Xe decreased drastically after annealing at 900 °C. And the XPS measurement barely detected the Xe. There was no change in the photoluminescence of YSZ single crystals with a fluence of 1 × 10 17 ion/cm 2 after annealing up to 900 °C.

  9. 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.

  10. XPS Investigation of Surface Secondary Phase Segregation in CIGS Thin Film

    SciTech Connect

    Al-Thani, H. A.; Abdullah, M. M.; Hasoon, F. S.

    2011-01-01

    Cu(In, Ga)Se{sub 2} (CIGS) thin films were deposited on Molybdenum (Mo) coated soda lime glass (SLG/Mo) substrates, using physical vapor deposition (PVD) 3-stage process. The Mo thin films were sputtered on SLG substrates using DC planar magnetron sputtering at a working gas (Ar) pressure that varies from 0.8 mT to 12 mT with a sputtering power density of 1.2 W/cm{sub 2}. The sputtering pressure of Mo thin films was varied in order to induce variations in the sputtered films morphology and porosity; as well as to subsequently induce variations in the Na out-diffusion from SLG substrate. The surface chemistry of CIGS thin films was investigated by X-Ray Photoelectron Spectroscopy (XPS). The XPS surface surveys (top 30A) and depth profiling survey (top 100A) for the elements, their chemical states, and their relative concentration were analyzed for CIGS thin films. The XPS surface analysis and composition of CIGS thin films were correlated to the bulk composition and Na out-diffusion in the CIGS films from SLG substrates.

  11. Morphological, chemical and structural characterisation of deciduous enamel: SEM, EDS, XRD, FTIR and XPS analysis.

    PubMed

    Zamudio-Ortega, C M; Contreras-Bulnes, R; Scougall-Vilchis, R J; Morales-Luckie, R A; Olea-Mejía, O F; Rodríguez-Vilchis, L E

    2014-09-01

    The purpose of this study was to characterise the enamel surface of sound deciduous teeth in terms of morphology, chemical composition, structure and crystalline phases. The enamel of 30 human deciduous teeth was examined by: Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Photoelectron Spectroscopy (XPS). Chemical differences between incisors and canines were statistically evaluated using the Mann-Whitney U test (p ≤ 0.05). Three enamel patterns were observed by SEM: 'mostly smooth with some groves', 'abundant microporosities' and 'exposed prisms'. The average Ca/P molar ratios were 1.37 and 1.03 by EDS and XPS, respectively. The crystallite size determined by XRD was 210.82 ± 16.78 Å. The mean ratio between Ca bonded to phosphate and Ca bonded to hydroxyl was approximately 10:1. The enamel of sound deciduous teeth showed two main patterns: 'mostly smooth with some groves' and 'abundant microporosities'. 'Exposed prisms' was a secondary pattern. There were slight variations among the Ca/P molar ratios found by EDS and XPS, suggesting differences in the mineral content from the enamel surface to the interior. The crystalline phases found in enamel were hydroxyapatite and carbonate apatite, with major type B than type A carbonate incorporation.

  12. Increase of xanthan production by cloning xps genes into wild-type Xanthomonas campestris.

    PubMed

    Tseng, Y H; Ting, W Y; Chou, H C; Yang, B Y; Chen, C C

    1992-02-01

    Previously, genomic banks of Xanthomonas campestris were constructed in Escherichia coli, using mobilizable broad-host-range cosmids as the vectors. Following conjugal transfer, genes involved in the biosynthesis of xanthan polysaccharide (XPS) were cloned by the ability to restore the mucoid phenotype to the non-mucoid mutants. In this study, all clones were transferred into the wild-type strain Xc17 to evaluate the effects of the cloned genes on XPS production. Most clones showed no significant effect; however, two plasmids, pP2401 and pP2201, caused 10 and 15% yield increases, respectively, compared with that of controls. While it was not clear how pP2201 caused the yield increase, the effect of pP2401 seemed to result from elevated phosphomannose isomerase activity. Since XPS synthesis in X. campestris is a very efficient process, only relatively small increases are to be expected; an enhancement of productivity by 10-15% is important to the commercial production of xanthan.

  13. 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.

  14. 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+.

  15. Synthesis and electrochemical performance of Li2Co1− xMxPO4F (M = Fe, Mn) cathode materials

    PubMed Central

    Drozhzhin, Oleg A; Fedotov, Stanislav S; Storozhilova, Darya A; Panin, Rodion V; Antipov, Evgeny V

    2013-01-01

    Summary In the search for high-energy materials, novel 3D-fluorophosphates, Li2Co1− xFexPO4F and Li2Co1− xMnxPO4F, have been synthesized. X-ray diffraction and scanning electron microscopy have been applied to analyze the structural and morphological features of the prepared materials. Both systems, Li2Co1− xFexPO4F and Li2Co1− xMnxPO4F, exhibited narrow ranges of solid solutions: x ≤ 0.3 and x ≤ 0.1, respectively. The Li2Co0.9Mn0.1PO4F material demonstrated a reversible electrochemical performance with an initial discharge capacity of 75 mA·h·g−1 (current rate of C/5) upon cycling between 2.5 and 5.5 V in 1 M LiBF4/TMS electrolyte. Galvanostatic measurements along with cyclic voltammetry supported a single-phase de/intercalation mechanism in the Li2Co0.9Mn0.1PO4F material. PMID:24367755

  16. 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.

  17. Cohort study comparing prostate photovaporisation with XPS 180W and HPS 120W laser.

    PubMed

    López, B; Capitán, C; Hernández, V; de la Peña, E; Jiménez-Valladolid, I; Guijarro, A; Pérez-Fernández, E; Llorente, C

    2016-01-01

    Prostate photovaporisation with Greenlight laser for the surgical treatment of benign prostate hyperplasia has rapidly evolve to the new XPS 180W. We have previously demonstrated the safety and efficacy of the HPS 120W. The aim of this study was to assess the functional and safety results, with a year of follow-up, of photovaporisation using the XPS 180W laser compared with its predecessor. A cohort study was conducted with a series of 191 consecutive patients who underwent photovaporisation between 1/2008 and 5/2013. The inclusion criteria were an international prostate symptom score (IPSS) >15 after medical failure, a prostate volume <80 cm(3) and a maximum flow <15 mL/s. We assessed preoperative and intraoperative variables (energy used, laser time and total surgical time), complications, catheter hours, length of stay and functional results (maximum flow, IPSS, prostate-specific antigen and prostate volume) at 3, 6 and 12 months. We analysed the homogeneity in preoperative characteristics of the 2 groups through univariate analysis techniques. The postoperative functional results were assessed through an analysis of variance of repeated measures with mixed models. A total of 109 (57.1%) procedures were performed using HPS 120W, and 82 (42.9%) were performed using XPS. There were no differences between the preoperative characteristics. We observed significant differences both in the surgical time and effective laser time in favour of the XPS system. This advantage was 11% (48 ± 15.7 vs. 53.8 ± 16.2, p<.05) and 9% (32.8 ± 11.7 vs. 36 ± 11.6, p<.05), respectively. There were no statistically significant differences in the rest of the analysed parameters. The technical improvements in the XPS 180W system help reduce surgical time, maintaining the safety and efficacy profile offered by the HPS 120W system, with completely superimposable results at 1 year of follow-up. Copyright © 2015 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

  18. In-Situ XPS Monitoring and Characterization of Electrochemically Prepared Au Nanoparticles in an Ionic Liquid

    PubMed Central

    2017-01-01

    Gold nanoparticles (Au NPs) have been electrochemically prepared in situ and in vacuo using two different electrochemical device configurations, containing an ionic liquid (IL), N-N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, that serves both as reaction and as stabilizing media for the NPs. It was observed in both devices that Au NPs were created using an anodically triggered route. The created Au NPs are relatively small (3–7 nm) and reside within the IL medium. X-ray photoelectron spectroscopy is utilized to follow not only the formation of the NPs but also their charging/discharging properties, by monitoring the charging shifts of the Au4f peak representing the electrodes and also the Au NPs as well as the F1s peak of the IL after polarizing one of the electrodes. Accordingly, DC polarization across the electrodes leads to a uniform binding energy shift of F1s of the IL along with that of Au4f of the NPs within. Moreover, this shift corresponds to only half of the applied potential. AC polarization brings out another dimension for demonstrating further the harmony between the charging/discharging property of the IL medium and the Au NPs in temporally and laterally resolved fashions. Polarization of the electrodes result in perfect spectral separation of the Au4f peaks of the NPs from those of the metal in both static (DC) and in time- and position-dependent (AC) modes. PMID:28261688

  19. Analytical characterization and pharmacological evaluation of the new psychoactive substance 4-fluoromethylphenidate (4F-MPH) and differentiation between the (±)-threo and (±)-erythro diastereomers.

    PubMed

    McLaughlin, Gavin; Morris, Noreen; Kavanagh, Pierce V; Power, John D; Dowling, Geraldine; Twamley, Brendan; O'Brien, John; Hessman, Gary; Murphy, Brian; Walther, Donna; Partilla, John S; Baumann, Michael H; Brandt, Simon D

    2017-03-01

    Misuse of (±)-threo-methylphenidate (methyl-2-phenyl-2-(piperidin-2-yl)acetate; Ritalin®; MPH) has long been acknowledged, but the appearance of MPH analogs in the form of 'research chemicals' has only emerged in more recent years. 4-Fluoromethylphenidate (4F-MPH) is one of these recent examples. This study presents the identification and analytical characterization of two powdered 4F-MPH products that were obtained from an online vendor in 2015. Interestingly, the products appeared to have originated from two distinct batches given that one product consisted of (±)-threo-4F-MPH isomers whereas the second sample consisted of a mixture of (±)-threo and (±)-erythro 4F-MPH. Monoamine transporter studies using rat brain synaptosomes revealed that the biological activity of the 4F-MPH mixture resided with the (±)-threo and not the (±)-erythro isomers based on higher potencies determined for blockage of dopamine uptake (IC50 4F-MPHmixture  = 66 nM vs. IC50 (±)-threo = 61 nM vs. IC50 (±)-erythro = 8,528 nM) and norepinephrine uptake (IC50 4F-MPHmixture  = 45 nM vs. (±)-threo = 31 nM vs. IC50 (±)-erythro = 3,779 nM). In comparison, MPH was three times less potent than (±)-threo-4F-MPH at the dopamine transporter (IC50  = 131 nM) and around 2.5 times less potent at the norepinephrine transporter (IC50  = 83 nM). Both substances were catecholamine selective with IC50 values of 8,805 nM and >10,000 nM for (±)-threo-4F-MPH and MPH at the serotonin transporter. These findings suggest that the psychostimulant properties of (±)-threo-4F-MPH might be more potent in humans than MPH. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  20. Ne{sup +} ion sputtering effect on amorphous Ga-In-Zn-O thin-film surface investigated by high-resolution XPS

    SciTech Connect

    Kang, Se-Jun; Lee, Mi Ji; Baik, Jae Yoon; Kim, Hyeong-Do; Thakur, Anup; Shin, Hyun-Joon; Chung, JaeGwan; Lee, Eunha; Lee, Jaecheol; Lee, JaeHak

    2011-12-23

    The effect of Ne{sup +} ion sputtering on amorphous Ga-In-Zn-O (a-GIZO) thin films was investigated by using surface-sensitive, synchrotron-radiation-based, high-resolution X-ray photoelectron spectroscopy (XPS). a-GIZO thin films having different compositions (Ga{sub 2}O{sub 3}:In{sub 2}O{sub 3}:ZnO = 1:1:1, 2:2:1, 3:2:1, 4:2:1) were investigated. It was found out that the amounts of the In and Zn contents relative to that of Ga decreased noticeably after sufficient sputtering, and that there occurred a subgap state above the valence band maximum and metallic states at the In 3d and 4d core levels as well as at the Fermi edge.

  1. Operando XPS Characterization of Selective Contacts: The Case of Molybdenum Oxide for Crystalline Silicon Heterojunction Solar Cells

    SciTech Connect

    Ding, Laura; Harvey, Stephen P.; Teeter, Glenn; Bertoni, Mariana I.

    2016-11-21

    We demonstrate the potential of X-ray photoelectron spectroscopy (XPS) to characterize new carrier-selective contacts (CSC) for solar cell application. We show that XPS not only provides information about the surface chemical properties of the CSC material, but that operando XPS, i.e. under light bias condition, can also directly measure the photovoltage that develops at the CSC/absorber interface, revealing device relevant information without the need of assembling a full solar cell. We present the application of the technique to molybdenum oxide hole-selective contact films on a crystalline silicon absorber.

  2. 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

  3. 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.

  4. D4F alleviates macrophage-derived foam cell apoptosis by inhibiting CD36 expression and ER stress-CHOP pathway[S

    PubMed Central

    Yao, Shutong; Tian, Hua; Miao, Cheng; Zhang, Da-Wei; Zhao, Li; Li, Yanyan; Yang, Nana; Jiao, Peng; Sang, Hui; Guo, Shoudong; Wang, Yiwei; Qin, Shucun

    2015-01-01

    This study was designed to explore the protective effect of D4F, an apoA-I mimetic peptide, on oxidized LDL (ox-LDL)-induced endoplasmic reticulum (ER) stress-CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) pathway-mediated apoptosis in macrophages. Our results showed that treating apoE knockout mice with D4F decreased the serum ox-LDL level and apoptosis in atherosclerotic lesions with concomitant downregulation of cluster of differentiation 36 (CD36) and inhibition of ER stress. In vitro, D4F inhibited macrophage-derived foam cell formation. Furthermore, like ER stress inhibitor 4-phenylbutyric acid (PBA), D4F inhibited ox-LDL- or tunicamycin (TM, an ER stress inducer)-induced reduction in cell viability and increase in lactate dehydrogenase leakage, caspase-3 activation, and apoptosis. Additionally, like PBA, D4F inhibited ox-LDL- or TM-induced activation of ER stress response as assessed by the reduced nuclear translocation of activating transcription factor 6 and the decreased phosphorylation of protein kinase-like ER kinase and eukaryotic translation initiation factor 2α, as well as the downregulation of glucose-regulated protein 78 and CHOP. Moreover, D4F mitigated ox-LDL uptake by macrophages and CD36 upregulation induced by ox-LDL or TM. These data indicate that D4F can alleviate the formation and apoptosis of macrophage-derived foam cells by suppressing CD36-mediated ox-LDL uptake and subsequent activation of the ER stress-CHOP pathway. PMID:25635126

  5. Association of 4F2hc with light chains LAT1, LAT2 or y+LAT2 requires different domains.

    PubMed

    Bröer, A; Friedrich, B; Wagner, C A; Fillon, S; Ganapathy, V; Lang, F; Bröer, S

    2001-05-01

    Heterodimeric amino acid transporters are comprised of a type-II membrane protein named the heavy chain (4F2hc or rBAT) that may associate with a number of different polytopic membrane proteins, called light chains. It is thought that the heavy chain is mainly involved in the trafficking of the complex to the plasma membrane, whereas the transport process itself is catalysed by the light chain. The 4F2 heavy chain (4F2hc) associates with at least six different light chains to induce distinct amino acid-transport activites. To test if the light chains are specifically recognized and to identify domains involved in the recognition of light chains, C-terminally truncated mutants of 4F2hc were constructed and co-expressed with the light chains LAT1, LAT2 and y(+)LAT2. The truncated isoform T1, comprised of only 133 amino acids that form the cytosolic N-terminus and the transmembrane helix, displayed only a slight reduction in its ability to promote LAT1 expression at the membrane surface compared with the 529 amino acid wild-type 4F2hc protein. Co-expression of increasingly larger 4F2hc mutants caused a delayed translocation of LAT1. In contrast to the weak effects of 4F2hc truncations on LAT1 expression, surface expression of LAT2 and y(+)LAT2 was almost completely lost with all truncated heavy chains. Co-expression of LAT1 together with the other light chains did not result in displacement of LAT2 and y(+)LAT2. The results suggest that extracellular domains of the heavy chain are responsible mainly for recognition of light chains other than LAT1 and that the extracellular domain ensures proper translocation to the plasma membrane.

  6. Association of 4F2hc with light chains LAT1, LAT2 or y+LAT2 requires different domains.

    PubMed Central

    Bröer, A; Friedrich, B; Wagner, C A; Fillon, S; Ganapathy, V; Lang, F; Bröer, S

    2001-01-01

    Heterodimeric amino acid transporters are comprised of a type-II membrane protein named the heavy chain (4F2hc or rBAT) that may associate with a number of different polytopic membrane proteins, called light chains. It is thought that the heavy chain is mainly involved in the trafficking of the complex to the plasma membrane, whereas the transport process itself is catalysed by the light chain. The 4F2 heavy chain (4F2hc) associates with at least six different light chains to induce distinct amino acid-transport activites. To test if the light chains are specifically recognized and to identify domains involved in the recognition of light chains, C-terminally truncated mutants of 4F2hc were constructed and co-expressed with the light chains LAT1, LAT2 and y(+)LAT2. The truncated isoform T1, comprised of only 133 amino acids that form the cytosolic N-terminus and the transmembrane helix, displayed only a slight reduction in its ability to promote LAT1 expression at the membrane surface compared with the 529 amino acid wild-type 4F2hc protein. Co-expression of increasingly larger 4F2hc mutants caused a delayed translocation of LAT1. In contrast to the weak effects of 4F2hc truncations on LAT1 expression, surface expression of LAT2 and y(+)LAT2 was almost completely lost with all truncated heavy chains. Co-expression of LAT1 together with the other light chains did not result in displacement of LAT2 and y(+)LAT2. The results suggest that extracellular domains of the heavy chain are responsible mainly for recognition of light chains other than LAT1 and that the extracellular domain ensures proper translocation to the plasma membrane. PMID:11311135

  7. Oxo-functionalization and reduction of the uranyl ion through lanthanide-element bond homolysis: synthetic, structural, and bonding analysis of a series of singly reduced uranyl-rare earth 5f1-4f(n) complexes.

    PubMed

    Arnold, Polly L; Hollis, Emmalina; Nichol, Gary S; Love, Jason B; Griveau, Jean-Christophe; Caciuffo, Roberto; Magnani, Nicola; Maron, Laurent; Castro, Ludovic; Yahia, Ahmed; Odoh, Samuel O; Schreckenbach, Georg

    2013-03-13

    The heterobimetallic complexes [{UO2Ln(py)2(L)}2], combining a singly reduced uranyl cation and a rare-earth trication in a binucleating polypyrrole Schiff-base macrocycle (Pacman) and bridged through a uranyl oxo-group, have been prepared for Ln = Sc, Y, Ce, Sm, Eu, Gd, Dy, Er, Yb, and Lu. These compounds are formed by the single-electron reduction of the Pacman uranyl complex [UO2(py)(H2L)] by the rare-earth complexes Ln(III)(A)3 (A = N(SiMe3)2, OC6H3Bu(t)2-2,6) via homolysis of a Ln-A bond. The complexes are dimeric through mutual uranyl exo-oxo coordination but can be cleaved to form the trimetallic, monouranyl "ate" complexes [(py)3LiOUO(μ-X)Ln(py)(L)] by the addition of lithium halides. X-ray crystallographic structural characterization of many examples reveals very similar features for monomeric and dimeric series, the dimers containing an asymmetric U2O2 diamond core with shorter uranyl U═O distances than in the monomeric complexes. The synthesis by Ln(III)-A homolysis allows [5f(1)-4f(n)]2 and Li[5f(1)-4f(n)] complexes with oxo-bridged metal cations to be made for all possible 4f(n) configurations. Variable-temperature SQUID magnetometry and IR, NIR, and EPR spectroscopies on the complexes are utilized to provide a basis for the better understanding of the electronic structure of f-block complexes and their f-electron exchange interactions. Furthermore, the structures, calculated by restricted-core or all-electron methods, are compared along with the proposed mechanism of formation of the complexes. A strong antiferromagnetic coupling between the metal centers, mediated by the oxo groups, exists in the U(V)Sm(III) monomer, whereas the dimeric U(V)Dy(III) complex was found to show magnetic bistability at 3 K, a property required for the development of single-molecule magnets.

  8. A near ambient pressure XPS study of subnanometer silver clusters on Al2O3 and TiO2 ultrathin film supports

    DOE PAGES

    Mao, Bao -Hua; Chang, Rui; Shi, Lei; ...

    2014-10-29

    Here, we have investigated model systems of silver clusters with different sizes (3 and 15 atoms) deposited on alumina and titania supports using ambient pressure X-ray photoelectron spectroscopy. The electronic structures of silver clusters and support materials are studied upon exposure to various atmospheres (ultrahigh vacuum, O2 and CO) at different temperatures. Compared to bulk silver, the binding energies of silver clusters are about 0.55 eV higher on TiO2 and 0.95 eV higher on Al2O3 due to the final state effect and the interaction with supports. No clear size effect of the silver XPS peak is observed on different silvermore » clusters among these samples. Silver clusters on titania show better stability against sintering. Al 2p and Ti 2p core level peak positions of the alumina and titania support surfaces change upon exposure to oxygen while the Ag 3d core level position remains unchanged. We discuss the origin of these core level shifts and their implications for catalytic properties of Ag clusters.« less

  9. 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

  10. A new supramolecular assembly based on triple-Dawson-type polyoxometalate and 3d-4f heterometallic cluster.

    PubMed

    Li, Yun-Wu; Li, Yang-Guang; Wang, Yong-Hui; Feng, Xiao-Jia; Lu, Ying; Wang, En-Bo

    2009-07-20

    The introduction of hexavacant Dawson-type precursor K(12)[H(2)P(2)W(12)O(48)] x 24 H(2)O into a HOAc/NaOAc (OAc(-) = acetate) buffer system containing (NH(4))(2)[Ce(IV)(NO(3))(6)] and Mn(II)(OAc)(2) x 4 H(2)O led to the isolation of a new compound, Na(20)[Ce(IV)(3)Mn(IV)(2)O(6)(OAc)(6)(H(2)O)(9)](2)[Mn(III)(2)P(2)W(16)O(60)](3) x 21 H(2)O (1). Compound 1 contains unusual triple-Dawson-type polyoxoanions [Mn(III)(2)P(2)W(16)O(60)](3)(24-) and bipyramid-like 3d-4f heterometallic clusters [Ce(IV)(3)Mn(IV)(2)O(6)(OAc)(6)(H(2)O)(9)](2+), which are arranged in a 3-D supramolecular assembly with 1-D channels. The Na(+) cations and solvent water molecules reside in the channels. Crystal data for 1 are as follows: hexagonal, P6(3)/mcm (No. 193), a = 24.959(4) A, c = 26.923(5) A, gamma = 120 degrees, V = 14525(4) A(3), and Z = 2. The electrochemical and electrocatalytic properties of compound 1 have been investigated.

  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. 3d-4f {Co(II)3Ln(OR)4} Cubanes as Bio-Inspired Water Oxidation Catalysts.

    PubMed

    Evangelisti, Fabio; Moré, René; Hodel, Florian; Luber, Sandra; Patzke, Greta Ricarda

    2015-09-02

    Although the {CaMn4O5} oxygen evolving complex (OEC) of photosystem II is a major paradigm for water oxidation catalyst (WOC) development, the comprehensive translation of its key features into active molecular WOCs remains challenging. The [Co(II)3Ln(hmp)4(OAc)5H2O] ({Co(II)3Ln(OR)4}; Ln = Ho-Yb, hmp = 2-(hydroxymethyl)pyridine) cubane WOC series is introduced as a new springboard to address crucial design parameters, ranging from nuclearity and redox-inactive promoters to operational stability and ligand exchange properties. The {Co(II)3Ln(OR)4} cubanes promote bioinspired WOC design by newly combining Ln(3+) centers as redox-inactive Ca(2+) analogues with flexible aqua-/acetate ligands into active and stable WOCs (max. TON/TOF values of 211/9 s(-1)). Furthermore, they open up the important family of 3d-4f complexes for photocatalytic applications. The stability of the {Co(II)3Ln(OR)4} WOCs under photocatalytic conditions is demonstrated with a comprehensive analytical strategy including trace metal analyses and solution-based X-ray absorption spectroscopy (XAS) investigations. The productive influence of the Ln(3+) centers is linked to favorable ligand mobility, and the experimental trends are substantiated with Born-Oppenheimer molecular dynamics studies.

  13. Collimator with filtration compensator: clinical adaptation to meet European Union recommendation 4F on radiological protection for dental radiography.

    PubMed

    Alcaraz, M; García-Vera, M C; Bravo, L A; Martínez-Beneyto, Y; Armero, D; Morant, J J; Canteras, M

    2009-09-01

    Our aim was to develop a compensated filtration collimator for use in paediatric patients undergoing cephalometric radiography that reduces the radiation dose administered and fulfils recommendation 4F of the European guidelines on radiation protection in dental radiology. An easy to use filtration-compensated collimator was constructed of plastic, lead and aluminium and used randomly with a group of 32 children (mean age 11 years) undergoing cephalometric radiography before receiving orthodontic treatment. The radiation doses administered to patients (eye lens and thyroid, submandibular and parotid glands) and to the chassis of the radiographic equipment were determined. The filtration-compensated collimator is easily fixed to the external surface of the radiographic equipment and results in (a) as collimator, a reduction of 40% in the surface irradiated in the children and of 61.4% in the dose administered to the thyroid glands (P<0.001); (b) as filtration compensator, a reduction of 32.8% administered to the eye lens (P<0.001), 31.45% to the submaxillary gland (P<0.01) and 11.4% to the parotid gland (P<0.05); there was no difference in the dose determined on the radiographic film. A radiographic examination can be carried out with children using only a third of the dose normally used with no increase in the time or cost involved.

  14. Highly compact (4F2) and well behaved nano-pillar transistor controlled resistive switching cell for neuromorphic system application.

    PubMed

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

    2014-10-31

    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 4F(2) 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.

  15. Behavior of fluorocarbon species near temperature controlled and radio frequency biased metal plate in C4F8 plasma

    NASA Astrophysics Data System (ADS)

    Doh, Hyun-Ho; Horiike, Yasuhiro

    2002-07-01

    Variations of fluorocarbon species were investigated in the vicinity of metal stage that was installed in C4F8 inductively coupled plasma system with the parameters such as temperature of the stage, distance from the stage, gas residence time, and rf bias voltage applied to the stage. Quadrupole mass analyzer and appearance mass spectrometry have been used for the measurement of fluorocarbon ions, radicals. Densities of all radicals increased with the increase of stage temperature and the decrease of the gap distance between stage and detection point. On the other side, the concentrations of fluorocarbon ions decreased slightly when the stage temperature went down. It has been investigated that the density variation of the radicals dependent on the stage temperature could be controlled with gas residence time. It is considered that the balance between pumping loss rate and surface loss rate has a responsibility for the residence time effects on radical density variations. Finally, constant amounts of radicals were desorbed from the stage along with discharge time when we applied rf bias to the stage. All of the experimental results suggest that dielectric etching chamber should be designed on the basis of the understanding on plasma-wall interaction. copyright 2002 American Vacuum Society.

  16. De novo facioscapulohumeral muscular dystrophy defined by DNA probe p13E-11 (D4F104S1).

    PubMed Central

    Jardine, P E; Koch, M C; Lunt, P W; Maynard, J; Bathke, K D; Harper, P S; Upadhyaya, M

    1994-01-01

    Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant condition with variable age of onset and severity. Identification of a de novo DNA fragment by probe p13E-11 (D4F104S1) established the diagnosis of new mutation FSHD in 27 of 31 sporadic cases. The clinical data for these certain new mutation cases were as follows: 13 boys, 14 girls; mean age of onset 6.8 years; significant leg weakness in 19/27 (70%) (8/27 (30%) used wheelchairs at a mean age of 17.7 years); high tone sensorineural deafness in 10/27; visual acuity and direct ophthalmoscopy were normal. Congenital facial diplegia and sensorineural deafness in three children suggest that infantile FSHD is not a genetically separate disorder from FSHD. Ascertainment bias may explain the difference in severity between this group and typical familial cases. Molecular analysis for FSHD should be considered in children with either congenital or early onset facial weakness or diplegia. Images PMID:7979495

  17. NMR study of valence fluctuating state in rare-earth based materials with multi-4f electrons

    NASA Astrophysics Data System (ADS)

    Mito, Takeshi

    2013-02-01

    Intermetallic compounds containing rare-earth elements have been a focus of interest due to their variety of intriguing phenomena, such as heavy fermion, valence fluctuation, magnetism, and superconductivity. Nuclear magnetic resonance (NMR) has played an important role in uncovering electronic states in those rare-earth based materials at the microscopic level. Among them, while cerium based materials have been intensively studied, there are so far a little NMR investigations on materials containing other rare-earth elements, such as samarium, europium, ytterbium, and so on, in spite of their attractive properties. We have recently concentrated on investigating the valence fluctuating states in the compounds with multi-4f electron configurations by NMR. Intermediate valence compound SmB6 undergoes an insulator-metal transition at the critical pressure 6-10 GPa [1,2], accompanied by the occurrence of a long-range magnetic order. In order to investigate intimate relationships between the insulating gap-formation, valence change, and magnetization as a function of pressure, we have successfully performed 11B-NMR up to ˜6 GPa. In this talk, we shall also present the result on EuPtP which shows two valence transitions at 235 K and 190 K [3].

  18. Enhanced unique pattern of hematopoietic cell mobilization induced by the CXCR4 antagonist 4F-benzoyl-TN14003.

    PubMed

    Abraham, Michal; Biyder, Katia; Begin, Michal; Wald, Hanna; Weiss, Ido D; Galun, Eithan; Nagler, Arnon; Peled, Amnon

    2007-09-01

    An increase in the number of stem cells in blood following mobilization is required to enhance engraftment after high-dose chemotherapy and improve transplantation outcome. Therefore, an approach that improves stem cell mobilization is essential. The interaction between CXCL12 and its receptor, CXCR4, is involved in the retention of stem cells in the bone marrow. Therefore, blocking CXCR4 may result in mobilization of hematopoietic progenitor and stem cells. We have found that the CXCR4 antagonist known as 4F-benzoyl-TN14003 (T-140) can induce mobilization of hematopoietic stem cells and progenitors within a few hours post-treatment in a dose-dependent manner. Furthermore, although T-140 can also increase the number of white blood cells (WBC) in blood, including monocytes, B cells, and T cells, it had no effect on mobilizing natural killer cells. T-140 was found to efficiently synergize with granulocyte colony-stimulating factor (G-CSF) in its ability to mobilize WBC and progenitors, as well as to induce a 660-fold increase in the number of erythroblasts in peripheral blood. Comparison between the CXCR4 antagonists T-140 and AMD3100 showed that T-140 with or without G-CSF was significantly more potent in its ability to mobilize hematopoietic stem cells and progenitors into blood. These results demonstrate that different CXCR4 antagonists may have different therapeutic potentials.

  19. The CXCR4 antagonist 4F-benzoyl-TN14003 stimulates the recovery of the bone marrow after transplantation.

    PubMed

    Abraham, M; Beider, K; Wald, H; Weiss, I D; Zipori, D; Galun, E; Nagler, A; Eizenberg, O; Peled, A

    2009-08-01

    Cytopenia represents a significant complication after chemotherapy, irradiation before bone marrow (BM) transplantation or as a therapy for cancer. The mechanisms that determine the pace of BM recovery are not fully understood. During the recovery phase after chemotherapy or irradiation, the signals for retention of white blood cells within the BM increase significantly. This leads to a delay in the release of WBC, which can be overcome by targeting the CXCR4 axis with the antagonist 4F-benzoyl-TN14003 (T140). The delay in the release of WBC is also accompanied by suppression in the production of progenitor cells and mature cells by the BM stroma. Administration of T140 to mice transplanted with BM cells stimulates the production of all types of progenitors and mature cells, and increases the exit of mature cells to the periphery. Moreover, addition of T140, but not AMD3100, to BM stromal cultures stimulates the production of mature cells and progenitors from all lineages. The unique ability of the CXCR4 antagonist, T140 to stimulate the production and exit of WBC cells may be used as a novel therapeutic approach to overcome cytopenia associated with treatments for cancer and BM transplantation.

  20. 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

  1. 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)

  2. Judd-Ofelt analysis of the Er3+ (4f11) absorption intensities in Er3+-doped garnets

    NASA Astrophysics Data System (ADS)

    Sardar, Dhiraj K.; Bradley, William M.; Perez, John J.; Gruber, John B.; Zandi, Bahram; Hutchinson, J. Andrew; Trussell, C. Ward; Kokta, Milan R.

    2003-03-01

    Spectroscopic and laser properties of three different Er3+-doped garnet systems are characterized by employing the Judd-Ofelt (JO) analysis. The three garnet hosts are Y3Al5O12 (YAG), Y3Sc2Ga3O12 (YSGG), and Gd3Ga5O12 (GGG). The JO model has been applied to the room temperature absorption intensities of Er3+ (4f11) transitions to establish the so-called JO intensity parameters: Ω2, Ω4, and Ω6 in the three garnet hosts. The intensity parameters are used to determine the radiative decay rates (emission probabilities of transitions) and branching ratios of the Er3+ transitions from the excited state J manifolds to the lower-lying J' manifolds. The predicted decay rates and branching ratios of these Er3+ transitions in YAG, YSGG, and GGG hosts are compared. From the radiative decay rates, the radiative lifetimes of the Er3+ excited states are determined in the three garnets and are also compared. We also report the spectroscopic quality factors, Ω4/Ω6, obtained for the three garnets. The quantum efficiencies of the 4I13/2→4I15/2 Er3+ transition in YAG, YSGG, and GGG are determined to be ˜79%, 82%, and 85%, respectively.

  3. High-pressure synthesis and characterization of the first cerium fluoride borate CeB2O4F.

    PubMed

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

    2013-08-01

    CeB2O4F is the first cerium fluoride borate, which is exclusively built up of one-dimensional, infinite chains of condensed trigonal-planar [BO3](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(3), R1=0.0698, and wR2=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 [BO3](3-) groups. Furthermore, IR spectroscopy, Electron Micro Probe Analysis and temperature-dependent X-ray powder diffraction measurements were performed.

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

    PubMed

    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(2+)-Yb(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(2+)-doped CaF2 and SrF2, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb(2+)-Yb(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(14)-1A1g→ 4f(13)((2)F7/2)5deg-1T1u absorption in the Yb(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(3+) moiety is in the higher 4f(13)((2)F5/2) multiplet. The Yb(2+)-Yb(3+) → Yb(3+)-Yb(2+) IVCT emission consists of an Yb(2+) 5deg → Yb(3+) 4f7/2 charge transfer accompanied by a 4f7/2 → 4f5/2 deexcitation within the Yb(2+) 4f(13) subshell: [(2)F5/25deg,(2)F7/2] → [(2)F7/2,4f(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 CaF2, SrF2, BaF2, and SrCl2: the presence of IVCT luminescence in Yb-doped CaF2 and SrF2; its coexistence with regular 5d-4f emission in SrF2; its absence in BaF2 and SrCl2; the quenching of all emissions in BaF2; and the presence of additional 5d-4f emissions in SrCl2 which are absent in SrF2. They also allow to interpret and reproduce recent experiments on transient photoluminescence enhancement in Yb(2+)-doped CaF2 and SrF2, the

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

    NASA Astrophysics Data System (ADS)

    Barandiarán, Zoila; Seijo, Luis

    2014-12-01

    In this paper, we report the existence of intervalence charge transfer (IVCT) luminescence in Yb-doped fluorite-type crystals associated with Yb2+-Yb3+ 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 Yb2+-doped CaF2 and SrF2, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb2+-Yb3+ mixed valence pairs. The IVCT luminescence is very efficiently excited by a two-photon upconversion mechanism where each photon provokes the same strong 4f14-1A1g→ 4f13(2F7/2)5deg-1T1u absorption in the Yb2+ part of the pair: the first one, from the pair ground state; the second one, from an excited state of the pair whose Yb3+ moiety is in the higher 4f13(2F5/2) multiplet. The Yb2+-Yb3+ → Yb3+-Yb2+ IVCT emission consists of an Yb2+ 5deg → Yb3+ 4f7/2 charge transfer accompanied by a 4f7/2 → 4f5/2 deexcitation within the Yb2+ 4f13 subshell: [2F5/25deg,2F7/2] → [2F7/2,4f14]. 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 CaF2, SrF2, BaF2, and SrCl2: the presence of IVCT luminescence in Yb-doped CaF2 and SrF2; its coexistence with regular 5d-4f emission in SrF2; its absence in BaF2 and SrCl2; the quenching of all emissions in BaF2; and the presence of additional 5d-4f emissions in SrCl2 which are absent in SrF2. They also allow to interpret and reproduce recent experiments on transient photoluminescence enhancement in Yb2+-doped CaF2 and SrF2, the appearance of Yb2+ 4f-5d absorption bands in the excitation

  6. Effect of NQO1 and CYP4F2 genotypes on warfarin dose requirements in Hispanic–Americans and African–Americans

    PubMed Central

    Bress, Adam; Patel, Shitalben R; Perera, Minoli A; Campbell, Richard T; Kittles, Rick A; Cavallari, Larisa H

    2013-01-01

    Aim The objective of this study was to determine the additional contribution of NQO1 and CYP4F2 genotypes to warfarin dose requirements across two racial groups after accounting for known clinical and genetic predictors. Patients & methods The following were assessed in a cohort of 260 African–Americans and 53 Hispanic–Americans: clinical data; NQO1 p.P187S (*1/*2); CYP2C9*2, *3, *5, *6, *8 and *11; CYP4F2 p.V433M; and VKORC1 c.-1639G>A genotypes. Results Both the CYP4F2 433M (0.23 vs 0.06; p < 0.05) and NQO1*2 (0.27 vs. 0.18; p < 0.05) allele frequencies were higher in Hispanic–Americans compared with African–Americans. Multiple regression analysis in the Hispanic–American cohort revealed that each CYP4F2 433M allele was associated with a 22% increase in warfarin maintenance dose (p = 0.019). Possession of the NQO1*2 allele was associated with a 34% increase in warfarin maintenance dose (p = 0.004), while adjusting for associated genetic (CYP2C9, CYP4F2 and VKORC1) and clinical factors. In this population, the inclusion of CYP4F2 and NQO1*2 genotypes improved the dose variability explained by the model from 0.58 to 0.68 (p = 0.001), a 17% relative improvement. By contrast, there was no association between CYP4F2 or NQO1*2 genotype and therapeutic warfarin dose in African–Americans after adjusting for known genetic and clinical predictors. Conclusion In our cohort of inner-city Hispanic–Americans, the CYP4F2 and NQO1*2 genotypes significantly contributed to warfarin dose requirements. If our findings are confirmed, they would suggest that inclusion of the CYP4F2 and NQO1*2 genotypes in warfarin dose prediction algorithms may improve the predictive ability of such algorithms in Hispanic–Americans. PMID:23215885

  7. Effect of NQO1 and CYP4F2 genotypes on warfarin dose requirements in Hispanic-Americans and African-Americans.

    PubMed

    Bress, Adam; Patel, Shitalben R; Perera, Minoli A; Campbell, Richard T; Kittles, Rick A; Cavallari, Larisa H

    2012-12-01

    The objective of this study was to determine the additional contribution of NQO1 and CYP4F2 genotypes to warfarin dose requirements across two racial groups after accounting for known clinical and genetic predictors. The following were assessed in a cohort of 260 African-Americans and 53 Hispanic-Americans: clinical data; NQO1 p.P187S (*1/*2); CYP2C9*2, *3, *5, *6, *8 and *11; CYP4F2 p.V433M; and VKORC1 c.-1639G>A genotypes. Both the CYP4F2 433M (0.23 vs 0.06; p < 0.05) and NQO1*2 (0.27 vs 0.18; p < 0.05) allele frequencies were higher in Hispanic-Americans compared with African-Americans. Multiple regression analysis in the Hispanic-American cohort revealed that each CYP4F2 433M allele was associated with a 22% increase in warfarin maintenance dose (p = 0.019). Possession of the NQO1*2 allele was associated with a 34% increase in warfarin maintenance dose (p = 0.004), while adjusting for associated genetic (CYP2C9, CYP4F2 and VKORC1) and clinical factors. In this population, the inclusion of CYP4F2 and NQO1*2 genotypes improved the dose variability explained by the model from 0.58 to 0.68 (p = 0.001), a 17% relative improvement. By contrast, there was no association between CYP4F2 or NQO1*2 genotype and therapeutic warfarin dose in African-Americans after adjusting for known genetic and clinical predictors. In our cohort of inner-city Hispanic-Americans, the CYP4F2 and NQO1*2 genotypes significantly contributed to warfarin dose requirements. If our findings are confirmed, they would suggest that inclusion of the CYP4F2 and NQO1*2 genotypes in warfarin dose prediction algorithms may improve the predictive ability of such algorithms in Hispanic-Americans.

  8. TFE2 and GATA3 Enhance Induction of POU4F3 and Myosin VIIa Positive Cells in Nonsensory Cochlear Epithelium by ATOH1

    PubMed Central

    Masuda, Masatsugu; Pak, Kwang; Chavez, Eduardo; Ryan, Allen F.

    2012-01-01

    Transcription factors (TFs) can regulate different sets of genes to determine specific cell types by means of combinatorial codes. We previously identified closely-spaced TF binding motifs located 8.2-8.5 kb 5′ to the ATG of the murine Pou4f3 gene, a gene required for late hair cell (HC) differentiation and survival. These motifs, 100% conserved among four mammalian species, include a cluster of E-boxes preferred by TCF3/ATOH1 heterodimers as well as motifs for GATA factors and SP1. We hypothesized that these factors might interact to regulate the Pou4f3 gene and possibly induce a HC phenotype in non-sensory cells of the cochlea. Cochlear sensory epithelium explants were prepared from postnatal day 1.5 transgenic mice in which expression of GFP is driven by 8.5 kb of Pou4f3 5′ genomic DNA (Pou4f3/GFP). Electroporation was used to transfect cells of the greater epithelial ridge with multiple plasmids encoding human ATOH1 (hATOH1), hTCF3 (also known as E2A or TEF2), hGATA3, and hSP1. hATOH1 or hTCF3 alone induced Pou4f3/GFP cells but hGATA3 and hSP1 did not. hATOH1 but not hTCF3 induced conversion of greater epithelial ridge cells into Pou4f3/GFP and myosin VIIa double-positive cells. Transfection of hATOH1 in combination with hTCF3 or hGATA3 induced 2-3X more Pou4f3/GFP cells, and similarly enhanced Pou4f3/GFP and myosin VIIa double-positive cells, when compared to hATOH1 alone. Triple or quadruple TF combinations were generally not more effective than double TF combinations except in the middle turn, where co-transfection of hATOH1, hE2A, and hGATA3 was more effective than hATOH1 plus either hTCF3 or hGATA3. The results demonstrate that TFs can cooperate in regulation of the Pou4f3 gene and in the induction of at least one other element of a HC phenotype. Our data further indicate that combinations of TFs can be more effective than individual TFs in the inner ear. PMID:22985730

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

    PubMed Central

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

    2015-01-01

    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-RasV12-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

  10. UHV and Ambient Pressure XPS: Potentials for Mg, MgO, and Mg(OH)2 Surface Analysis

    NASA Astrophysics Data System (ADS)

    Head, Ashley R.; Schnadt, Joachim

    2016-12-01

    The surface sensitivity of x-ray photoelectron spectroscopy (XPS) has positioned the technique as a routine analysis tool for chemical and electronic structure information. Samples ranging from ideal model systems to industrial materials can be analyzed. Instrumentational developments in the past two decades have popularized ambient pressure XPS, with pressures in the tens of mbar now commonplace. Here, we briefly review the technique, including a discussion of developments that allow data collection at higher pressures. We illustrate the information XPS can provide by using examples from the literature, including MgO studies. We hope to illustrate the possibilities of ambient pressure XPS to Mg, MgO, and Mg(OH)2 systems, both in fundamental and applied studies.

  11. XPS investigation of thin SiO x and SiO xN y overlayers

    NASA Astrophysics Data System (ADS)

    Birer, Ö.; Sayan, Ş.; Süzer, Ş.; Aydınlı, A.

    1999-05-01

    Angle-resolved XPS is used to determine the thickness and the uniformity of the chemical composition with respect to oxygen and nitrogen of the very thin silicon oxide and oxynitride overlayers grown on silicon.

  12. Mutation in the Hair Cell Specific Gene POU4F3 Is a Common Cause for Autosomal Dominant Nonsyndromic Hearing Loss in Chinese Hans

    PubMed Central

    He, Longxia; Pang, Xiuhong; Chen, Penghui

    2016-01-01

    Autosomal dominant nonsyndromic hearing loss (ADNSHL) is extremely heterogeneous. So far the genetic etiological contribution of the gene POU4F3 associated with ADNSHL has been rarely reported. In our previous study, a c.603_604delGG mutation in the hair cell specific gene POU4F3 has been identified as the pathogenic cause in one of the seven Chinese Han ADNSHL families. In the present study, we performed targeted next-generation sequencing of 144 known deafness genes in another nine Chinese Han ADNSHL families and identified two more novel mutations in POU4F3, p.Leu311Pro and c.120+1G>C, as the pathogenic cause. Clinical characterization of the affected individuals in these three families showed that the three POU4F3 mutations may lead to progressive hearing loss with variable ages of onset and degrees of severity. Our results suggested that mutations in POU4F3 are a relatively common cause (3/16) for ADNSHL in Chinese Hans, which should be routinely screened in such cases during genetic testing. PMID:28053790

  13. Targeted partial surface modification with nano-SiO2@Li2CoPO4F as high-voltage cathode material for LIBs

    NASA Astrophysics Data System (ADS)

    Chang, Caiyun; Huang, Zhipeng; Tian, Runsai; Jiang, Xinyu; Li, Chunsheng; Feng, Jijun

    2017-10-01

    Tuning whole/partial surface modification on cathode material with oxide material is a sought-after method to enhance the electrochemical performance in power storage field. Herein, nano-SiO2 targeted partial surface modified high voltage cathode material Li2CoPO4F has been successfully fabricated via a facile self-assembly process in silica dispersion at ambient temperature. With the aid of polar -OH groups attracted on the surface of SiO2 micelles, the nano-SiO2 preferentially nestle up along the borders and boundaries of Li2CoPO4F particles, where protection should be deployed with emphasis against the undesirable interactions between materials and electrolytes. Compared with pristine Li2CoPO4F, the SiO2 selectively modified Li2CoPO4F cathode materials, especially LCPF-3S, exhibit desirable electrochemical performances with higher discharge capacity, more outstanding cycle stability and favorable rate capability without any additional carbon involved. The greatly enhanced electrochemical properties can be attributed to the improved lithium-ion diffusion kinetics and structure tolerance during repeated lithiation/delithiation process. Such findings reveal a great potential of nano-SiO2 modified Li2CoPO4F as high energy cathode material for lithium ion batteries.

  14. A novel missense variant in the nuclear localization signal of POU4F3 causes autosomal dominant non-syndromic hearing loss.

    PubMed

    Lin, Yin-Hung; Lin, Yi-Hsin; Lu, Ying-Chang; Liu, Tien-Chen; Chen, Chien-Yu; Hsu, Chuan-Jen; Chen, Pei-Lung; Wu, Chen-Chi

    2017-08-08

    Autosomal dominant non-syndromic hearing loss (ADNSHL) is genetically heterogeneous with more than 35 genes identified to date. Using a massively parallel sequencing panel targeting 159 deafness genes, we identified a novel missense variant of POU4F3 (c.982A>G, p.Lys328Glu) which co-segregated with the deafness phenotype in a three-generation Taiwanese family with ADNSHL. This variant could be classified as a "pathogenic variant" according to the American College of Medical Genetics and Genomics guidelines. We then performed subcellular localization experiments and confirmed that p.Lys328Glu compromised transportation of POU4F3 from the cytoplasm to the nucleus. POU3F4 p.Lys328Glu was located within a bipartite nuclear localization signal (NLS), and was the first missense variant in bipartite NLS of POU4F3 validated in functional studies. These findings expanded the mutation spectrum of POU4F3 and provided insight into the pathogenesis associated with aberrant POU4F3 localization.

  15. Essential role of the cytochrome P450 CYP4F22 in the production of acylceramide, the key lipid for skin permeability barrier formation

    PubMed Central

    Ohno, Yusuke; Nakamichi, Shota; Ohkuni, Aya; Kamiyama, Nozomi; Naoe, Ayano; Tsujimura, Hisashi; Yokose, Urara; Sugiura, Kazumitsu; Ishikawa, Junko; Akiyama, Masashi; Kihara, Akio

    2015-01-01

    A skin permeability barrier is essential for terrestrial animals, and its impairment causes several cutaneous disorders such as ichthyosis and atopic dermatitis. Although acylceramide is an important lipid for the skin permeability barrier, details of its production have yet to be determined, leaving the molecular mechanism of skin permeability barrier formation unclear. Here we identified the cytochrome P450 gene CYP4F22 (cytochrome P450, family 4, subfamily F, polypeptide 22) as the long-sought fatty acid ω-hydroxylase gene required for acylceramide production. CYP4F22 has been identified as one of the autosomal recessive congenital ichthyosis-causative genes. Ichthyosis-mutant proteins exhibited reduced enzyme activity, indicating correlation between activity and pathology. Furthermore, lipid analysis of a patient with ichthyosis showed a drastic decrease in acylceramide production. We determined that CYP4F22 was a type I membrane protein that locates in the endoplasmic reticulum (ER), suggesting that the ω-hydroxylation occurs on the cytoplasmic side of the ER. The preferred substrate of the CYP4F22 was fatty acids with a carbon chain length of 28 or more (≥C28). In conclusion, our findings demonstrate that CYP4F22 is an ultra-long-chain fatty acid ω-hydroxylase responsible for acylceramide production and provide important insights into the molecular mechanisms of skin permeability barrier formation. Furthermore, based on the results obtained here, we proposed a detailed reaction series for acylceramide production. PMID:26056268

  16. Essential role of the cytochrome P450 CYP4F22 in the production of acylceramide, the key lipid for skin permeability barrier formation.

    PubMed

    Ohno, Yusuke; Nakamichi, Shota; Ohkuni, Aya; Kamiyama, Nozomi; Naoe, Ayano; Tsujimura, Hisashi; Yokose, Urara; Sugiura, Kazumitsu; Ishikawa, Junko; Akiyama, Masashi; Kihara, Akio

    2015-06-23

    A skin permeability barrier is essential for terrestrial animals, and its impairment causes several cutaneous disorders such as ichthyosis and atopic dermatitis. Although acylceramide is an important lipid for the skin permeability barrier, details of its production have yet to be determined, leaving the molecular mechanism of skin permeability barrier formation unclear. Here we identified the cytochrome P450 gene CYP4F22 (cytochrome P450, family 4, subfamily F, polypeptide 22) as the long-sought fatty acid ω-hydroxylase gene required for acylceramide production. CYP4F22 has been identified as one of the autosomal recessive congenital ichthyosis-causative genes. Ichthyosis-mutant proteins exhibited reduced enzyme activity, indicating correlation between activity and pathology. Furthermore, lipid analysis of a patient with ichthyosis showed a drastic decrease in acylceramide production. We determined that CYP4F22 was a type I membrane protein that locates in the endoplasmic reticulum (ER), suggesting that the ω-hydroxylation occurs on the cytoplasmic side of the ER. The preferred substrate of the CYP4F22 was fatty acids with a carbon chain length of 28 or more (≥C28). In conclusion, our findings demonstrate that CYP4F22 is an ultra-long-chain fatty acid ω-hydroxylase responsible for acylceramide production and provide important insights into the molecular mechanisms of skin permeability barrier formation. Furthermore, based on the results obtained here, we proposed a detailed reaction series for acylceramide production.

  17. 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.

  18. 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.

  19. 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.

  20. Thermal chemistry of copper acetamidinate atomic layer deposition precursors on silicon oxide surfaces studied by XPS

    SciTech Connect

    Yao, Yunxi; Zaera, Francisco

    2016-01-15

    The thermal surface chemistry of copper(I)-N,N′-di-sec-butylacetamidinate, [Cu({sup s}Bu-amd)]{sub 2}, a metalorganic complex recently proposed for the chemical-based deposition of copper films, has been characterized on SiO{sub 2} films under ultrahigh vacuum conditions by x-ray photoelectron spectroscopy (XPS). Initial adsorption at cryogenic temperatures results in the oxidation of the copper centers with Cu 2p{sub 3/2} XPS binding energies close to those seen for a +2 oxidation state, an observation that the authors interpret as the result of the additional coordination of oxygen atoms from the surface to the Cu atoms of the molecular acetamidinate dimer. Either heating to 300 K or dosing the precursor directly at that temperature leads to the loss of one of its two ligands, presumably via hydrogenation/protonation with a hydrogen/proton from a silanol group, or following a similar reaction on a defect site. By approximately 500 K the Cu 2p{sub 3/2}, C 1s, and N 1s XPS data suggest that the remaining acetamidinate ligand is displaced from the copper center and bonds to the silicon oxide directly, after which temperatures above 900 K need to be reached to promote further (and only partial) decomposition of those organic moieties. It was also shown that the uptake of the Cu precursor is self-limiting at either 300 or 500 K, although the initial chemistry is somewhat different at the two temperatures, and that the nature of the substrate also defines reactivity, with the thin native silicon oxide layer always present on Si(100) surfaces being less reactive than thicker films grown by evaporation, presumably because of the lower density of surface nucleation sites.

  1. 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.

  2. 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.

  3. An XPS study on the covalent immobilization of adhesion peptides on a glass surface

    NASA Astrophysics Data System (ADS)

    Iucci, G.; Battocchio, C.; Dettin, M.; Ghezzo, F.; Polzonetti, G.

    2010-11-01

    Covalent attachment of adhesive peptides to biomaterials surfaces can result in the formation of a bioactive and biomimetic surface. We have demonstrated that titanium surfaces grafted with adhesion peptides, reproducing sequences of fibronectin and vitronectin, can increase osteoblast adhesion compared to non-treated surfaces. We now extend our investigation to peptide immobilization on glass for studying human osteoblast adhesion and spreading. Silanization was used to anchor adhesion peptides to the glass surface through a selective or a non-selective immobilization. Investigated samples were analysed by XPS spectroscopy. Comparison between the results obtained using two different peptides and applying selective and non-selective immobilization will be discussed.

  4. Note: Heated sample platform for in situ temperature-programmed XPS.

    PubMed

    Samokhvalov, Alexander; Tatarchuk, Bruce J

    2011-07-01

    We present the design, fabrication, and performance of the multi-specimen heated platform for linear in situ heating during the Temperature-Programmed XPS (TPXPS). The platform is versatile, compatible with high vacuum (HV) and bakeout. The heater platform is tested under in situ linear heating of typical high surface area sorbent∕catalyst support--nanoporous TiO(2). The platform allows the TPXPS of multiple samples located on specimen disk that can be transferred in and out of the TPXPS chamber. Electric characteristics, temperature and pressure curves are provided. Heating power supply, PID temperature controller, data-logging hardware and software are described.

  5. 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

  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. 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.

  8. Functional characterization of the Xcs and Xps type II secretion systems from the plant pathogenic bacterium Xanthomonas campestris pv vesicatoria.

    PubMed

    Szczesny, Robert; Jordan, Matthias; Schramm, Claudia; Schulz, Steve; Cogez, Virginie; Bonas, Ulla; Büttner, Daniela

    2010-09-01

    *Type II secretion (T2S) systems of many plant-pathogenic bacteria often secrete cell wall-degrading enzymes into the plant apoplast. *Here, we show that the Xps-T2S system from the plant pathogen Xanthomonas campestris pv vesicatoria (Xcv) promotes disease and contributes to the translocation of effector proteins that are delivered into the plant cell by the type III secretion (T3S) system. *The Xcs-T2S system instead lacks an obvious virulence function. However, individual xcs genes can partially complement mutants in homologous xps genes, indicating that they encode functional components of T2S systems. Enzyme activity assays showed that the Xps system contributes to secretion of proteases and xylanases. We identified the virulence-associated xylanase XynC as a substrate of the Xps system. However, homologs of known T2S substrates from other Xanthomonas spp. are not secreted by the T2S systems from Xcv. Thus, T2S systems from Xanthomonas spp. appear to differ significantly in their substrate specificities. *Transcript analyses revealed that expression of xps genes in Xcv is activated by HrpG and HrpX, key regulators of the T3S system. By contrast, expression of xynC and extracellular protease and xylanase activities are repressed by HrpG and HrpX, suggesting that components and substrates of the Xps system are differentially regulated.

  9. 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

  10. 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.

  11. Experimental observation of temperature and magnetic-field evolution of the 4 f states in CeFe2 revealed by soft x-ray magnetic circular dichroism

    NASA Astrophysics Data System (ADS)

    Saitoh, Y.; Yasui, A.; Fuchimoto, H.; Nakatani, Y.; Fujiwara, H.; Imada, S.; Narumi, Y.; Kindo, K.; Takahashi, M.; Ebihara, T.; Sekiyama, A.

    2017-07-01

    We revisit the delocalized character of the 4 f states of CeFe2 in the ferromagnetically ordered phase by x-ray magnetic circular dichroism (XMCD) in x-ray absorption spectroscopy (XAS) with improved data quality using single crystals. Surprisingly, the Ce M4 ,5 XMCD spectral shape changes significantly as a function of temperature and applied magnetic field, with no concomitant changes in the spectral shape of the Ce M4 ,5 XAS as well as the Fe L2 ,3 XAS and XMCD. This unusual behavior is characterized by the J =7 /2 states in a 4 f1 configuration mixed into the J =5 /2 ground state. Such extreme sensitivity of the Ce 4 f states to the external perturbations can be related to the magnetic instability toward an antiferromagnetic phase in CeFe2. Our experimental data presented here provide valuable insights into the underlying physics in strongly hybridized ferromagnetic Ce compounds.

  12. J dependences of the isotope shift and hyperfine structure in the Sm i 4f65d6s 9H term

    NASA Astrophysics Data System (ADS)

    Jin, W. G.; Horiguchi, T.; Yang, W.; Endo, I.

    1994-06-01

    Isotope shifts and hyperfine structures of twelve transitions from the high-lying metastable 9HJ (J=1-7) states of the 4f65d6s configuration in Sm i have been measured for the stable isotopes by means of atomic-beam laser spectroscopy. Hyperfine constants A and B for the odd-mass isotopes 147Sm and 149Sm are determined for the 9HJ (J=1-7) states and six upper levels of the transitions in Sm i. $J- dependences of the isotope shifts are observed for the 4f65d6s 9H term. Parameters z5d of the crossed-second-order effect are derived for the 4f65d6s configuration, and z5d/λ is found to be 165(10) MHz/fm2. It has been verified that the field shift is dominant in the crossed-second-order effect.

  13. Energy gaps in the 4f(13)5d(1) manifold and multiple spontaneous emissions in Yb(2+)-doped CsCaBr(3).

    PubMed

    Sánchez-Sanz, Goar; Seijo, Luis; Barandiarán, Zoila

    2009-11-12

    Multiple spontaneous 4f(13)5d(1) --> 4f(14) emissions are predicted in Yb(2+)-doped CsCaBr(3) crystals by ab initio quantum chemical calculations. Four emission bands are found at 23,900, 26,600, 34,600, and 43,900 cm(-1) that should be experimentally observable at low temperatures. The first, third, and fourth bands are slow, electric dipole forbidden emissions that can be described as spin-forbidden. The second band is a fast, electric dipole-allowed emission that cannot be described as spin-allowed, but as spin-enabled; its radiative emission lifetime is 400 ns. Large energy gaps (23 900, 4600, 4000 cm(-1), respectively), relative to the maximum local phonon energies calculated (around 185 cm(-1)), are found below the emitting levels of the slow bands, which indicates that these states should be significantly stable and multiphonon relaxation to the lower states should be negligible. A smaller gap (2600 cm(-1)) separates the states of the fast band, which should result in a temperature dependent competition between radiative and nonradiative decay. Differential correlation between 4f-4f and 4f-5d pairs, splitting of the 5d shell by interactions with the host, and spin-orbit effects within the 4f(13) subshell, are found to be responsible for the existence of the gaps, which, in turn, split the absorption spectrum into four groups of separate bands, three of which could lie below the host absorption threshold. The quantum chemical methods employed make use of explicit wave functions expanded in terms of flexible basis sets, multiconfigurational self-consistent-field and multireference second-order perturbation methods to account for nondynamic and dynamic electron correlation, scalar and relativistic terms in the (YbBr(6))(4-) defect cluster Hamiltonian, and quantum mechanical embedding potentials to represent the host crystal.

  14. Rapid kinetics of iron responsive element (IRE) RNA/iron regulatory protein 1 and IRE-RNA/eIF4F complexes respond differently to metal ions

    PubMed Central

    Khan, Mateen A.; Ma, Jia; Walden, William E.; Merrick, William C.; Theil, Elizabeth C.; Goss, Dixie J.

    2014-01-01

    Metal ion binding was previously shown to destabilize IRE-RNA/IRP1 equilibria and enhanced IRE-RNA/eIF4F equilibria. In order to understand the relative importance of kinetics and stability, we now report rapid rates of protein/RNA complex assembly and dissociation for two IRE-RNAs with IRP1, and quantitatively different metal ion response kinetics that coincide with the different iron responses in vivo. kon, for FRT IRE-RNA binding to IRP1 was eight times faster than ACO2 IRE-RNA. Mn2+ decreased kon and increased koff for IRP1 binding to both FRT and ACO2 IRE-RNA, with a larger effect for FRT IRE-RNA. In order to further understand IRE-mRNA regulation in terms of kinetics and stability, eIF4F kinetics with FRT IRE-RNA were determined. kon for eIF4F binding to FRT IRE-RNA in the absence of metal ions was 5-times slower than the IRP1 binding to FRT IRE-RNA. Mn2+ increased the association rate for eIF4F binding to FRT IRE-RNA, so that at 50 µM Mn2+ eIF4F bound more than 3-times faster than IRP1. IRP1/IRE-RNA complex has a much shorter life-time than the eIF4F/IRE-RNA complex, which suggests that both rate of assembly and stability of the complexes are important, and that allows this regulatory system to respond rapidly to change in cellular iron. PMID:24728987

  15. Seven 3d-4f coordination polymers of macrocyclic oxamide with polycarboxylates: Syntheses, crystal structures and magnetic properties

    NASA Astrophysics Data System (ADS)

    Xin, Na; Sun, Ya-Qiu; Zheng, Yan-Feng; Xu, Yan-Yan; Gao, Dong-Zhao; Zhang, Guo-Ying

    2016-11-01

    Seven new 3d-4f heterometallic coordination polymers, [Ln(CuL)2(Hbtca)(btca)(H2O)]·2H2O (Ln = TbIII1, PrIII2, SmIII3, EuIII4, YbIII5), [Nd(NiL)(nip)(Rnip)]·0·25H2O·0.25CH3OH (R= 0.6CH3, 0.4H) 6 and [Nd2(NiL)(nip)3(H2O)]·2H2O 7(CuL or NiL, H2L = 2, 3-dioxo-5, 6, 14, 15-dibenzo-1, 4, 8, 12-tetraazacyclo-pentadeca-7, 13-dien; H2btca = benzotriazole-5-carboxylic acid; H2nip = 5-nitroisophthalic acid) have been synthesized by a solvothermal method and characterized by single-crystal X-ray diffraction. Complexes 1-5 exhibit a double-strand meso-helical chain structures formed by [LnIIICuII2] units via the oxamide and benzotriazole-5-carboxylate bridges, while complex 6 exhibits a four-strand meso-helical chain formed by NdNi unit via the oxamide and 5-nitroisophthalate bridges. Complex 7 consists of a 2D layer framework formed by four-strand meso-helical chain via the nip2- bridges. Moreover, the magnetic properties of them were investigated, and the best-fit analysis of χMT versus T show that the anisotropic contribution of Ln(III) ions (arising from the spin-orbit coupling or the crystal field perturbation) dominates (weak exchange limit) in these complexes(for 3, λ = 214.6 cm-1, zj' = -0.33 cm-1, gav = 1.94; for 5, Δ = 6.98 cm-1, zj' = 1.53 cm-1, gav = 1.85).

  16. Insights into bonding interactions and excitation energies of 3d-4f mixed lanthanide transition metal macrocyclic complexes.

    PubMed

    Rabanal-León, Walter A; Murillo-López, Juliana A; Arratia-Pérez, Ramiro

    2016-12-07

    In this contribution, a computational study of equatorial bound tetranuclear macrocycle (butylene linked) [LnZn(HOM(Bu))](3+) (Ln = La(3+), Ce(3+)) complexes was carried out. Here, the electronic structure, bonding interaction and excitation energies were studied within the relativistic density functional theory framework. From the electronic structure analysis, the frontier molecular orbitals (FMOs) were strongly localized in the d-orbitals of the Zn centers and the f-orbitals of the lanthanide ions. Besides, the inner MOs were found to exhibit a π-character from the organic part of the macrocyclic chain. EDA-NOCV was used as a tool for evaluating the bonding interaction, taking the trinuclear metallomacrocycle (ZnHOM(Bu)) and the lanthanide center as fragments. This analysis showed that the interaction between these fragments was slightly covalent; with this covalency being the result of a charge transfer from the metallomacrocyclic ring to the lanthanide. This phenomenon was observed in the deformation density channels obtained from the EDA-NOCV study; in which π- and σ-charge transfer was observed. Finally, the TD-DFT study of the excitation energies evidenced three sets of bands: the first set with the highest intensity represented the ligand to metal charge transfer bands; the second set could be attributed to the 3d-4f electronic transitions between the metal centers; and the third set represented the f-f bands found for the open-shell cerium complex. This class of complexes accomplishes the "antenna effect" principle, which states that highly absorptive transition-metal (TM) complexes can be used to enhance the luminescence of poorly emissive systems, and are introduced in this study as self-sensitizer bimetallic d-f systems with potential applications in near infra-red (NIR) technologies.

  17. An XPS round robin investigation on analysis of wood pulp fibres and filter paper

    NASA Astrophysics Data System (ADS)

    Johansson, Leena-Sisko; Campbell, J. M.; Fardim, Pedro; Hultén, Anette Heijnesson; Boisvert, Jean-Philippe; Ernstsson, Marie

    2005-06-01

    X-ray photoelectron spectroscopy (XPS) has been applied to pulp and paper research for decades. However, there has been no attempt to standardise or even systematically compare experimental and analysis procedures, even though it is known that fibrous, nature-derived and insulating fibre materials pose remarkable challenges to reliable surface analysis. The experimental problems are mainly linked with neutralisation, energy resolution, contamination and X-ray induced degradation. We have tested applicability, reliability and reproducibility of XPS analysis on real pulp samples with varying lignin and extractives contents in a small round robin investigation. We also tested the instrumental set-ups with an acetone-extracted filter paper, used as a reference sample. The data, collected at four different laboratories with state-of-the-art instruments indicate that reproducible results can be obtained, despite minor differences in experimental and analysis procedures. However, we found that a specified sample handling procedure and limited X-ray exposure are crucial for reproducible, reliable data. Based on the round robin data we recommend dose restricted monochromatic measurements, a cellulosic in situ reference and a consistent sample handling procedure. The data confirms that a paper-based reference material and the correlation of high-resolution C 1s data with O/C atomic ratios can be used in testing instruments and experimental set-ups for pulp and paper materials.

  18. An XPS study for mechanisms of arsenate adsorption onto a magnetite-doped activated carbon fiber.

    PubMed

    Zhang, Shujuan; Li, Xiao-yan; Chen, J Paul

    2010-03-01

    The surface and bulk structures of a newly developed carbon-based iron-containing adsorbent for As(V) adsorption were investigated by using X-ray diffraction (XRD), field emission scanning electronic microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). XRD patterns of the adsorbents indicated that the modified activated carbon fiber (MACF) was a simple mixture of the raw activated carbon fiber (RACF) and magnetite. After modification, a porous film was formed on the surface of the MACF with nano-sized magnetite on it. The As(V) uptake on the MACF was highly pH dependent and was facilitated in acidic solutions. XPS studies demonstrated that the surface oxygen-containing functional groups were involved in the adsorption and that magnetite played a key role in As(V) uptake. The dominance of HAsO(4)(2-) in surface complexes and the pH effect on As(V) uptake demonstrated that the monoprotonated bidentate complexes were dominant on the surface of the MACF. No reduction of As(V) was observed on the surface of the ACFs. 2009 Elsevier Inc. All rights reserved.

  19. The composition of polymer composite fracture surfaces as studied by XPS

    SciTech Connect

    Wiegand, D.A.; Pinto, J.J.

    1996-12-01

    The composition of the fracture surfaces of a composite made up of a polycrystalline organic nonpolymeric filler and a binder composed of a copolymer was studied by XPS. Because the binder and the filler of the composite each have at least one element not in common it is possible to easily distinguish between the binder and filler by XPS. A measure of the relative amounts of binder and filler on the fracture surfaces, therefore, could be made as a function of the sample temperature, T, and the strain rate during fracture. The ratio of filler to binder, F/B, increases with decreasing T at constant strain rate and is least sensitive to strain rate at T`s below T{sub G}, the quasi static glass transition T. At higher T, F/B increases with strain rate at constant T. These results indicate that as the binder becomes stronger and stiffer due to a decrease in T or an increase in strain rate more of the fracture processes take place in the filler whose properties are expected to be less sensitive to T and strain rate. These results are related to the fracture properties as observed by uniaxial compression.

  20. 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.

  1. Experimental study on the characteristics of horizontal flame spread over XPS surface on plateau.

    PubMed

    Zhang, Ying; Huang, Xinjie; Wang, Qingsong; Ji, Jie; Sun, Jinhua; Yin, Yi

    2011-05-15

    A series of comparative laboratory-scale experiments were carried out in the Lhasa plateau and the Hefei plain respectively to investigate the characteristics of flame spread over the extruded polystyrene (XPS) foam, a typical thermal insulation material. Flame shape and the temperature profile in solid phase were monitored, and the effects of altitude on the heat transfer process were analyzed. The results show that the temperature rise with time undergoes three stages: the preheating stage, the melting stage and the pyrolysis stage. The durations of the melting and pyrolysis stages on plateau are longer than that in plain, which sequentially results in a lower flame spread rate on plateau. Comparing of the temperature change rate curve on plateau with that in plain, it is found that the peak characteristics of the curves in the pyrolysis stage changed from single peak to multi-peaks, which suggests that the altitude difference might change the pyrolysis mechanisms of XPS material. Moreover, the sample scale effects on flame spread are also explored. Two different regimes are found in flame spread behavior with sample scale at the both altitudes. The spread rate drops with sample scale in convection regime and rises in radiation regime. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. [An FTIR and XPS study of immobilization of chromium with fly ash based geopolymers].

    PubMed

    Liu, Si-Feng; Wang, Pei-Ming; Li, Zong-Jin; Lo, Irene M C

    2008-01-01

    Immobilization of Cr3+ with fly ash geopolymers was investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopic (XPS) techniques. The chromium sludge, as Cr(OH)3, was prepared with chemical precipitation method. The amounts of aluminum and silicon leached before and after the chromium sludge addition were measured using ICP-AES. The results suggested that the amounts of silicon and aluminum leached were reduced for the fly ash geopolymers after chromium sludge was incorporated. The decrease of silicon leaching was more pronounced than aluminum. FTIR results showed that the intensity of the main peak shifted into lower and the wave number of Si--O--Si and Al--O--Si became higher. The XPS results indicated that the O(1s) bind energy decreased, Si(2p) and Cr(2p) bind energy increased, while Al(2p) bind energy remained unchanged due to Cr3+ addition. It was also confirmed that the chromium is easily incorporated into the fly ash geopolymers paste, and polymerized with silicate units. The immobilization of Cr3+ using fly ash geopolymers is attributed not only to physical encapsulation, but also to chemical reaction.

  3. Soil wettability can be explained by the chemical composition of particle interfaces - An XPS study

    PubMed Central

    Woche, Susanne K.; Goebel, Marc-O.; Mikutta, Robert; Schurig, Christian; Kaestner, Matthias; Guggenberger, Georg; Bachmann, Jörg

    2017-01-01

    Soil wettability (quantified in terms of contact angle, CA) is crucial for physical, chemical, and biological soil functioning. As the CA is determined by components present within the outmost nanometer of particles, this study applied X-ray photoelectron spectroscopy (XPS) with a maximum analysis depth of 10 nm to test the relationship between CA and surface elemental composition, using soil samples from a chronosequence where CA increased from 0° (0 yrs) to about 98° (120 yrs). Concurrently, as seen by XPS, C and N content increased and the content of O and the mineral-derived cations (Si, Al, K, Na, Ca, Mg, Fe) decreased. The C content was positively correlated with CA and least squares fitting indicated increasing amounts of non-polar C species with soil age. The contents of O and the mineral-derived cations were negatively correlated with CA, suggesting an increasing organic coating of the minerals that progressively masked the underlying mineral phase. The atomic O/C ratio was found to show a close negative relationship with CA, which applied as well to further sample sets of different texture and origin. This suggests the surface O/C ratio to be a general parameter linking surface wettability and surface elemental composition. PMID:28211469

  4. Combined XPS and contact angle studies of ethylene vinyl acetate and polyvinyl acetate blends

    NASA Astrophysics Data System (ADS)

    Ucar, I. O.; Doganci, M. D.; Cansoy, C. E.; Erbil, H. Y.; Avramova, I.; Suzer, S.

    2011-09-01

    In this study, we prepared thin films by blending ethylene vinyl acetate copolymers (EVA) containing 12-33 (wt.%) vinyl acetate (VA) with polyvinyl acetate (PVAc) and high density polyethylene homopolymers. Large area micropatterns having controlled protrusion sizes were obtained by phase-separation especially for the PVAc/EVA-33 blends using dip coating. These surfaces were characterized by XPS and contact angle measurements. A reasonably linear relation was found between the VA content on the surface (wt.%) obtained from XPS analysis and the VA content in bulk especially for PVAc/EVA-33 blend surfaces. PE segments were more enriched on the surface than that of the bulk for pure EVA copolymer surfaces similar to previous reports and VA enrichment was found on the EVA/HDPE blend surfaces due to high molecular weight of HDPE. Water θ decreased with the increase in the VA content on the blend surface due to the polarity of VA. A good agreement was obtained between γs- and atomic oxygen surface concentration with the increase of VA content. The applicability of Cassie-Baxter equation was tested and found that it gave consistent results with the experimental water contact angles for the case where VA content was lower than 55 wt.% in the bulk composition.

  5. FTIR and XPS studies of protein adsorption onto functionalized bioactive glass.

    PubMed

    Gruian, C; Vanea, E; Simon, S; Simon, V

    2012-07-01

    Adsorption and structural changes that occur upon interaction between methemoglobin (MetHb) and 5-methyl-aminomethyl-uridine forming enzyme (MnmE) with the surface of a bioactive glass (BG) were investigated by Fourier Transform Infrared (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The effect of glutaraldehyde (GA) as a coupling agent for protein adsorption on BG was also investigated. The comparative analysis of FTIR spectra recorded from lyophilized proteins and from bioactive glass surface after protein adsorption was considered in order to obtain information about the changes in the secondary structure of the proteins. XPS data were used to determine the surface coverage. The unfolding of adsorbed proteins due to interactions between the internal hydrophobic protein domains and the hydrophobic BG surface was evidenced. After adsorption, the amount of α-helix decreases and less ordered structures (turns, random coils and aggregates) are preponderant. These changes are less pronounced on the BG functionalized with GA, suggesting that the treatment with GA preserves significantly larger amounts of α-helices in the structure of both proteins after adsorption.

  6. 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.

  7. In-situ NAP XPS studies of dissociative water adsorption on GaAs(100) surfaces

    NASA Astrophysics Data System (ADS)

    Ptasinska, Sylwia; Zhang, Xueqiang

    2014-03-01

    In current semiconductor-based technology it is important to design and fabricate new materials in order to achieve specific well-defined properties and functionalities. Before such systems can be applied they first need to be understood, refined and controlled. Therefore, a basic knowledge about molecule/semiconductor surface interfaces is essential. In the present work dissociative water adsorption on the GaAs(100) surface is monitored using X-ray Photoelectron Spectroscopy (XPS) performed in situ under near ambient conditions. Firstly, the crystal surface is exposed to water vapor pressures ranging from UHV to 0.5 kPa. At elevated pressures an increase of oxygenation and hydroxylation of Ga surface atoms has been observed in the Ga2p XPS spectra. Moreover, intense signals obtained from molecularly adsorbed water molecules or water molecules adsorbed via hydrogen bond to surface OH groups have been also observed in the O1s spectra. Finally, the crystal surface is annealed up to 700 K at water vapor pressure of 0.01 kPa, which leads to desorption of physisorbed water molecules and further increase of surface oxidation. The research described herein was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, United States Department of Energy through grant number DE-FC02-04ER15533.

  8. 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

    2015-08-04

    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.

  9. Ensuring the homogeneity of spray pyrolised SnS thin films employing XPS depth profiling

    NASA Astrophysics Data System (ADS)

    Sajeesh, T. H.; Deepa, K. G.; Vijayakumar, K. P.

    2017-05-01

    SnS thin films were prepared using chemical spray pyrolysis (CSP) technique. p-type SnS films with direct band gap of 1.33 eV and having very high absorption coefficient were obtained with the optimized deposition conditions. In this paper we focus on investigating the uniformity and phase purity of the hence deposited SnS films employing Raman and X-ray Photoelectron Spectroscopy (XPS) analysis. Raman Spectra of the films had only single peak corresponding to the Raman active Ag mode at 224 cm-1 which is characteristic for phase-pure SnS thin films. Detailed XPS analysis on these samples were performed by scanning the peaks for Sn, S, and O with high resolution to estimate the chemical states and composition. Employing Ar-ion sputtering, the depth profiles showing variation in concentration and binding energies of S, Sn, O over the sample thickness were obtained and the uniformity in composition along the thickness has been discussed in detail.

  10. Investigation of damaged interior walls using synchrotron-based XPS and XANES.

    PubMed

    Poo-arporn, Yingyot; Thachepan, Surachai; Palangsuntikul, Rungtiva

    2015-01-01

    Evidence of internal sulfate attack in field exposure was demonstrated by the damaged interior wall of a three-year-old house situated in Nakhon Ratchasima Province, Thailand. Partial distension of the mortar was clearly observed together with an expansion of a black substance. Removal of the black substance revealed a dense black layer. This layer was only found in the vicinity of the damaged area, suggesting that this black material is possibly involved in the wall cracking. By employing synchrotron-based X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) techniques, the unknown sample was chemically identified. The S 2p and O 1s XPS results mutually indicated the existence of sulfate species in the materials collected from the damaged area. The XANES results indicated the presence of ferrous (II) sulfate, confirming sulfate-induced expansion and cracking. The sulfate attack in the present case appeared to physically affect the structure whereas the chemical integrity at the molecular level of the calcium silicate hydrate phase was retained since there was a lack of spectroscopic evidence for calcium sulfate. It was speculated that internal sulfate probably originated from the contaminated aggregates used during the construction. The current findings would be beneficial for understanding the sulfate-attack mechanism as well as for future prevention against sulfate attack during construction.

  11. An XPS analytical approach for elucidating the microbially mediated enargite oxidative dissolution.

    PubMed

    Fantauzzi, M; Rossi, G; Elsener, B; Loi, G; Atzei, D; Rossi, A

    2009-04-01

    In this work, the microbe-mediated oxidative dissolution of enargite surfaces (Cu(3)AsS(4)) was studied on powdered samples exposed to 9K nutrient solution (pH 2.3) inoculated by Acidithiobacillus ferrooxidans initially adapted to arsenopyrite. These conditions simulate the acid mine environment. The redox potential of the inoculated solutions increased up to +0.72 V vs normal hydrogen electrode (NHE), indicating the increase of the Fe(3+) to Fe(2+) ratio, and correspondingly the pH decreased to values as low as 1.9. In the sterile 9K control, the redox potential and pH remained constant at +0.52 V NHE and 2.34, respectively. Solution analyses showed that in inoculated medium Cu and As dissolved stoichiometrically with a dissolution rate of about three to five times higher compared to the sterile control. For the first time, X-ray photoelectron spectroscopy (XPS) was carried out on the bioleached enargite powder with the aim of clarifying the role of the microorganisms in the dissolution process. XPS results provide evidence of the formation of a thin oxidized layer on the mineral surface. Nitrogen was also detected on the bioleached surfaces and was attributed to the presence of an extracellular polymer substance layer supporting a mechanism of bacteria attachment via the formation of a biofilm a few nanometers thick, commonly known as nanobiofilm.

  12. ELS and XPS study of Pd/PdO methane oxidation catalysts

    NASA Astrophysics Data System (ADS)

    Hoflund, Gar B.; Hagelin, Helena A. E.; Weaver, Jason F.; Salaita, Ghaleb N.

    2003-01-01

    Electron energy loss spectra (ELS) and X-ray photoelectron spectroscopy (XPS) data obtained from palladium powder catalysts used for complete methane oxidation have been obtained in this study in order to gain information about the Pd chemical state. Metallic Pd and PdO yield significantly different ELS spectra making ELS useful for chemical-state determination. Palladium(II) oxide is readily detected by the presence of an energy loss feature at 3.7 eV. Species distribution in the direction normal to the surface can be determined using ELS by varying the primary beam energy. Both XPS and ELS data indicate that PdO forms during reaction, and the ELS data demonstrate that PdO forms as a film over the Pd metal. If any Pd metal is present in the PdO film, it is there at levels below the detection limit of ELS. These observations have important consequences with regard to the mechanism of methane oxidation over Pd-containing catalysts. Hydrous and anhydrous palladium(II) oxides have significantly different energy loss features in the low loss-energy region of the ELS spectra. ELS features attributed to water are observed at 5.5-6.5 and 8 eV for hydrous palladium(II) oxide.

  13. Formation of hydroxyl and water layers on MgO films studied with ambient pressure XPS

    NASA Astrophysics Data System (ADS)

    Newberg, John T.; Starr, David E.; Yamamoto, Susumu; Kaya, Sarp; Kendelewicz, Tom; Mysak, Erin R.; Porsgaard, Soeren; Salmeron, Miquel B.; Brown, Gordon E., Jr.; Nilsson, Anders; Bluhm, Hendrik

    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 2O) 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 2O, OH and Ox thickness changes as a function of relative humidity.

  14. AFM and XPS Study of Glass Surface Coated with Titania Nanofilms by Sol-Gel Method

    NASA Astrophysics Data System (ADS)

    Ji, Guo-Jun; Shi, Zhi-Ming

    2010-09-01

    Ce3+ -doped and undoped TiO2 nanofilms are prepared on glass surface using a sol-gel method. Crystal structure, surface morphology, chemical composition and element distribution of both glass substrates and TiO2 films were characterized by x-ray diffractometer (XRD), atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). The XRD results indicate that the Ce3+-doped TiO2 films are solely composed of the anatase phase whereas in the undoped films a small amount of the rutile phase of TiO2 is present. AFM observations show that there exist many micro-cracks and micro-holes on glass substrate surface. In contrast, the surface of pure titania films is crack-free and the average crystallite size of the films is less than 50 nm. For the films doped with Ce3+, not only does it appear to be more uniform and compact, but also the corresponding crystal size is decreased. XPS results indicate that element interdiffusion occurs between the titania nanofilm and the glass substrate during the sintering process. The film is firmly adhered onto the glass surface through the chemical combination of Ti-O-Si bonds, and the combination is more enhanced by Ce3+-doping.

  15. 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.

  16. Soil wettability can be explained by the chemical composition of particle interfaces - An XPS study

    NASA Astrophysics Data System (ADS)

    Woche, Susanne K.; Goebel, Marc-O.; Mikutta, Robert; Schurig, Christian; Kaestner, Matthias; Guggenberger, Georg; Bachmann, Jörg

    2017-02-01

    Soil wettability (quantified in terms of contact angle, CA) is crucial for physical, chemical, and biological soil functioning. As the CA is determined by components present within the outmost nanometer of particles, this study applied X-ray photoelectron spectroscopy (XPS) with a maximum analysis depth of 10 nm to test the relationship between CA and surface elemental composition, using soil samples from a chronosequence where CA increased from 0° (0 yrs) to about 98° (120 yrs). Concurrently, as seen by XPS, C and N content increased and the content of O and the mineral-derived cations (Si, Al, K, Na, Ca, Mg, Fe) decreased. The C content was positively correlated with CA and least squares fitting indicated increasing amounts of non-polar C species with soil age. The contents of O and the mineral-derived cations were negatively correlated with CA, suggesting an increasing organic coating of the minerals that progressively masked the underlying mineral phase. The atomic O/C ratio was found to show a close negative relationship with CA, which applied as well to further sample sets of different texture and origin. This suggests the surface O/C ratio to be a general parameter linking surface wettability and surface elemental composition.

  17. Spectroellipsometric, AFM and XPS probing of stainless steel surfaces subjected to biological influences

    NASA Astrophysics Data System (ADS)

    Vinnichenko, M.; Chevolleau, Th; Pham, M. T.; Poperenko, L.; Maitz, M. F.

    2002-11-01

    Surface modification of austenitic stainless steel (SS) 316L after incubation in growing cell cultures and cell-free media as control has been studied. The following treatments were applied: mouse fibrosarcoma cells L929 for 3 and 7 days, polymorphonuclear neutrophils for 3 and 7 days and human osteosarcoma cells SAOS-2 for 7 and 14 days. Cells were enzymatically removed in all cases. The modified surfaces were probed in comparison with untreated ones by means of spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). XPS shows the appearance of the peak of bonded nitrogen at 400.5 eV characteristic for adsorbed proteins on the surface for each type of cells and for the cell-free medium. Migration of Ni in the adsorbed layer is observed in all cases for samples after the cell cultures. The protein layer thickness is ellipsometrically determined to be within 2.5-6.0 nm for all treated samples with parameterization of its optical constants in Cauchy approach. The study showed that for such biological treatments of the SS the protein layer adsorption is the dominating process in the first 2 weeks, which could play a role in the process of corrosion by complex forming properties with metal ions.

  18. XPS and SAM studies of the surface chemistry of lunar impact glasses including 12054

    NASA Technical Reports Server (NTRS)

    Housley, R. M.; Grant, R. W.; Cirlin, E. H.

    1979-01-01

    We report and discuss quantitative X-ray photoemission (XPS) analyses of mm size areas and qualitative scanning Auger microprobe (SAM) analyses of micron size areas on the surfaces of impact glass coatings found on fragments in the 14161 coarse fines and on the top surface, and a reentrant crack surface of rock 12054. The data suggest that some segregation occurs during impact glass formation leading to surface enrichments in Si and depletions in Mg, Al, Ca, and Ti. The magnitude of the effect appears fairly small, although the complexity of the surfaces severely complicates the data analysis. Because of the complexity of the surfaces, both XPS and SAM data were essential. A search for direct evidence of either solar wind sputter erosion or vapor deposition on the exposed top surface of 12054 provided interesting results which we cannot yet fully interpret. Both this surface and the surface from the re-entrant crack showed enrichments of more than a factor of two in Fe with respect to the bulk.

  19. 4f-5d Transitions of Tb3+ in Cs2NaYF6: the effect of distortion of the excited-state configuration.

    PubMed

    Duan, Chang-Kui; Tanner, Peter A; Meijerink, Andries; Makhov, Vladimir

    2011-08-25

    The low-temperature absorption and excitation spectra of interconfigurational 4f-5d transitions of Tb(3+) in a cubic fluoride host demonstrate the appearance of a first-order linear Jahn-Teller effect for the high-spin excited states of the excited electronic configuration 4f(7)5d involving 5d t(2g) orbitals. The τ(2g) mode is observed to be responsible for the splitting of the otherwise degenerate 5d t(2g) orbitals.

  20. Structural, magnetic and XPS studies of Sn0.95Co0.05O2-0.05 and Sn0.95Fe0.05O2-0.05 nanoparticles

    NASA Astrophysics Data System (ADS)

    Kaur, Jasneet; Sahni, Kunal; Kumar, Vikas; Thakur, Kartik; Kotnala, R. K.; Verma, Kuldeep Chand

    2013-02-01

    Structural, microstructural, X-ray photoemission spectra (XPS) and magnetic properties of transition metal ion [5 mol% of Co (SC5) and Fe (SF5)]-doped SnO2 nanoparticles have been studied. The SC5 and SF5 nanoparticles were synthesized by a chemical route using polyvinyl alcohol as surfactant. The doped SnO2 crystallites were found to exhibit a tetragonal rutile structure and the average grains size was measured by the Scherer relation of X-ray diffraction. Transmission electron micrographs showed that the average grain size of SC5 is smaller than SF5. SC5 nanoparticles showed strong ferromagnetic behaviour but SF5 exhibited an F-centre exchange (FCE) mechanism. Temperature-dependent magnetization showed the values of phase transition temperature. XPS confirmed the presence of Sn-O-Co and Sn-O-Fe bonds in these SC5 and SF5 nanoparticles. The oxidation states of Sn, Co and Fe were found to be +4, +2 and +2, respectively, while the core level XPS peaks of Sn 3d, O 1s, Co 2p and Fe 2p were analyzed.

  1. Comparison of thermal lensing effects between single-end and double-end diffusion-bonded Nd:YVO4 crystals for 4F 3/2-->4I 11/2 and 4F 3/2-->4I 13/2 transitions.

    PubMed

    Chang, Y T; Huang, Y P; Su, K W; Chen, Y F

    2008-12-08

    The effective focal lengths of thermal lens in diode-end-pumped continuous-wave Nd:YVO(4) lasers for the (4)F(3/2)-->(4)I(11/2) and (4)F(3/2)-->(4)I(13/2) transitions were determined. The experimental results revealed that the thermal lensing effect for the (4)F(3/2)-->(4)I(11/2) transition can be sufficiently improved by employing a single-end diffusion-bonded Nd:YVO(4) crystal replacing a conventional Nd:YVO(4) crystal. However, using a double-end diffusion-bonded Nd:YVO(4) crystal was a great improvement over a single-end diffusion-bonded Nd:YVO(4) crystal for the (4)F(3/2)-->(4)I(13/2) transition with stronger thermal lensing effect.

  2. Origin of the core-level binding energy shifts in Au nanoclusters

    NASA Astrophysics Data System (ADS)

    Tal, Alexey A.; Olovsson, Weine; Abrikosov, Igor A.

    2017-06-01

    We investigate the shifts of the core-level binding energies in small gold nanoclusters by using ab initio density-functional-theory calculations. The shift of the 4 f states is calculated for magic-number nanoclusters in a wide range of sizes and morphologies. We find a nonmonotonous behavior of the core-level shift in nanoclusters depending on the size. We demonstrate that there are three main contributions to the Au 4 f shifts, which depend sensitively on the interatomic distances, coordination, and quantum confinement. They are identified and explained by the change of the on-site electrostatic potential.

  3. Core transfer

    NASA Astrophysics Data System (ADS)

    Good news for all petroleum geoscientists, mining and environmental scientists, university researchers, and the like: Shell Oil Company has deeded its Midland core and sample repository to the Bureau of Economic Geology (BEG) at the University of Texas at Austin. The Midland repository includes more than 1 million linear meters of slab, whole core, and prepared cuttings. Data comprising one of the largest U.S. core collections—the geologic samples from wells drilled in Texas and 39 other states—are now public data and will be incorporated into the existing BEG database. Both Shell and the University of Texas at Austin are affiliated with the American Geological Institute, which assisted in arranging the transfer as part of its goal to establish a National Geoscience Data Repository System at regional centers across the United States.

  4. 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

  5. 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.

  6. Physical and Chemical Behaviors of HCl on Ice Surface: Insights from an XPS and NEXAFS Study

    NASA Astrophysics Data System (ADS)

    Kong, X.; Waldner, A.; Orlando, F.; Birrer, M.; Artiglia, L.; Ammann, M.; Bartels-Rausch, T.

    2016-12-01

    Ice and snow play active roles for the water cycle, the energy budget of the Earth, and environmental chemistry in the atmosphere and cryosphere. Trace gases can be taken up by ice, and physical and chemical fates of the impurities could modify surface properties significantly and consequently influence atmospheric chemistry and the climate system. However, the understanding of chemical behaviour of impurities on ice surface are very poor, which is largely limited by the difficulties to apply high sensitivity experimental approaches to ambient air conditions, e.g. studies of volatile surfaces, because of the strict requirements of vacuum experimental conditions. In this study, we employed synchrotron-based X-ray photoelectron spectroscopy (XPS) and partial electron yield Near Edge X-ray Absorption Fine Structure (NEXAFS) in a state-of-the-art near-ambient pressure photoelectron (NAPP) spectroscopy end station. The NAPP enables to utilize the surface sensitive experimental methods, XPS and NEXAFS, on volatile surfaces, i.e. ice at temperatures approaching 0°C. XPS and NEXAFS together provide unique information of hydrogen bonding network, dopants surface concentration, dopant depth profile, and acidic dissociation on the surfaces1. Taking the advantages of the highly sensitive techniques, the adsorption, dissociation and depth profile of Hydrogen Chloride (HCl) on ice were studied. In brief, two states of Chloride on ice surface are identified from the adsorbed HCl, and they are featured with different depth profiles along the ice layers. Combining our results and previously reported constants from literatures (e.g. HCl diffusion coefficients in ice)2, a layered kinetic model has been constructed to fit the depth profiles of two states of Chloride. On the other side, pure ice and doped ice are compared for their surface structure change caused by temperature and the presence of HCl, which shows how the strong acid affect the ice surface in turn. 1. Orlando, F., et

  7. [Analysis of XPS in the removal of Se(IV) from groundwater with pyrite].

    PubMed

    Liu, Hong-fang; Qian, Tian-wei; Zhang, Min-gang

    2015-02-01

    Selenium (Se) is an elementary trace nutrient element for human but there is a very narrow range between deficit and toxic levels. Furthermore, excessive intake of Selenium is harmful for human. The product species of selenite which was removal by pyrite particles was studied in the present research In the experiments, the pyrite particles were prepared by the wet ball mill method, and surface analyses of pyrite before and after contact with Se(IV) were conducted using X-ray photoelectron spectroscopy (XPS). Besides, the prepared pyrite samples were also characterized using both X-ray diffraction (XRD) and scanning electron microscope (SEM). X-ray diffraction analysis indicated that the purity of the prepared pyrite particles was above 97%, and the characteristic diffraction peaks of the particles well matched with that of FeS2 crystalline. Scanning electron microscope determination showed the shape of the particles was approximate ball and the size was range from 80 to 180 nm. And thus the pyrite particles prepared by the wet ball mill method had less particle size, larger specific surface area and higher reactive ability. The batch experiments exhibited the pyrite particles were able to remove 95% of Se(IV) (20 mg x L(-1)) from water within 12 hours. And the kinetic tests indicated reaction process between pyrite and Se(IV) fits a pseudo-first order kinetic model, which gives a pseudo-first order rate constant(kobs) of 0.26 h(-1). XPS analyses were using the XPSPEAK program which has a Gaussian Lorentzian function. The results clearly displays that Se(IV) prefer to react with the surface-bound S2(2-) rather than reacted with the surface-bound Fe2+ of pyrite particles. From XPS graph, it can be seen that the binding energy of sulfur element and iron element composed of pyrite shifted to the left a little, which means expensive state of sulfur element and iron element appeared on the pyrite surface. Analysis of the oxidation state of Se on the surface of pyrite

  8. X-ray atomic orbital analysis of 4f and 5d electron configuration of SmB6 at 100, 165, 230 and 298 K.

    PubMed

    Funahashi, Shiro; Tanaka, Kiyoaki; Iga, Fumitoshi

    2010-06-01

    Accurate electron-density measurement of SmB(6) at 100, 165, 230 and 298 K, and X-ray atomic orbital (XAO) analysis were carried out. The 4f-electron density around Sm and 5d electron density at approximately 1 A from Sm were analysed by XAO analysis. The 5d electron density is due to the electrons of the 5d(J = 5/2)Gamma(8) orbitals which stem from the e(g) orbitals in the strong field approximation. The change in electron populations of the 5d(5/2)Gamma(8) orbitals with temperature is similar to that of the resistivity. Since the conduction band consists of 5d(5/2)Gamma(8) and B-2p orbitals according to band theory, this indicates that the larger populations of the 5d(5/2)Gamma(8) orbitals correspond to the larger number of localized electrons and are correlated to the resistivity of SmB(6). The occupation of the bulky 5d(5/2)Gamma(8) orbitals may be the reason for the elongation of the lattice parameter below 150 K. The 4f(7/2)Gamma(6) orbitals are obviously occupied except at 100 K, which seems to be caused by the energy gap between 4f(5/2) and 4f(7/2) states, which begins to exist between 100 and 150 K, and may represent one of the properties of a Kondo insulator.

  9. Self-assembled 3D architectures of Bi2TiO4F2 as a new durable visible-light photocatalyst.

    PubMed

    Jiang, Bo; Zhang, Peng; Zhang, Ya; Wu, Ling; Li, Hexing; Zhang, Dieqing; Li, Guisheng

    2012-01-21

    A new hierarchical visible-light-driven photocatalyst Bi(2)TiO(4)F(2) was synthesized by a solvothermal method for the first time. The photocatalyst was characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N(2) adsorption-desorption (BET), UV-vis diffuse reflectance spectroscopy (DRS). Such hierarchical Bi(2)TiO(4)F(2) microspheres assembled by nanosheets were fabricated via an Ostwald ripening process in the absence of soft templates (surfactants). The as-prepared samples' bimodal pore-size distributions in the mesoporous region consisted of smaller intra-aggregated pores with peak pore diameter of ca. 4.6 nm and larger inter-aggregated pores with peak pore diameter of ca. 17.0 nm. The band gap of the obtained Bi(2)TiO(4)F(2) was estimated to be about 2.71-3.06 eV for various solvothermal treatment time. Owing to the hierarchical structure with bimodal pores, low band gaps and high crystallinity, the Bi(2)TiO(4)F(2) microspheres exhibited high photocatalytic performance and durability for the degradation of rhodamine B (RhB) under visible light (> 420 nm). It was proved that the photo-generated holes and ˙OH radicals played an essential role for the oxidation of RhB.

  10. Effect of temperature on the low-energy (≲1eV) electron attachment to perfluorocyclobutane ( c-C 4F 8)

    NASA Astrophysics Data System (ADS)

    Christodoulides, A. A.; Christophorou, L. G.; Mccorkle, D. L.

    1987-08-01

    A large decrease in the total electron attachment rate constant Kfor cC 4F 8 with increasing temperature T (300 to 560 K) has been observed for mean electron energies <ɛ> ≲ 0.8 eV, where the electron attachment is non-dissociative. Possible origins for the observed large negative effect of temperature on Ka(<ɛ>) are discussed.

  11. 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.

  12. Expression of the surface antigen 4F2hc affects system-L-like neutral-amino-acid-transport activity in mammalian cells.

    PubMed Central

    Bröer, S; Bröer, A; Hamprecht, B

    1997-01-01

    Mammalian cells possess a variety of amino acid-transport systems with overlapping substrate specificity. System L is one of the major amino acid-transport systems of non-epithelial cells. By expression cloning we have recently demonstrated that the surface antigen 4F2hc (CD98) is a necessary component for expression of system-L-like amino acid-transport activity in C6-BU-1 rat glioma cells [Bröer, Bröer and Hamprecht (1995) Biochem. J. 312, 863-870]. 4F2hc mRNA was detected in CHO cells, COS cells, activated lymphocytes isolated from mouse spleen and primary cultures of astrocytes. In all these cell types, Na+-independent isoleucine transport was mediated by system L. No contribution of system y+L to isoleucine or arginine transport was detected in C6-BU-1 cells. In lymphocytes, both system-L-like amino acid-transport activity and 4F2hc mRNA levels increased after treatment with phorbol ester plus ionomycin. Antisense oligonucleotides caused modest inhibition of Na+-independent isoleucine transport in C6-BU-1 cells and primary cultures of astroglial cells, whereas arginine transport was unaffected. Overexpression of 4F2hc cDNA in CHO cells resulted in an increase in Na+-independent isoleucine transport. PMID:9182715

  13. Synthesis and biological activity of 5-methylidene 1,2-dihydrochromeno[3,4-f]quinoline derivatives as progesterone receptor modulators.

    PubMed

    Zhi, Lin; Tegley, Christopher M; Pio, Barbara; Edwards, James P; Jones, Todd K; Marschke, Keith B; Mais, Dale E; Risek, Boris; Schrader, William T

    2003-06-16

    A series of 5-methylidene 1,2-dihydrochromeno[3,4-f]quinoline derivatives were synthesized and tested in biological assays to evaluate scope and limitations of the nonsteroidal SPRM pharmacophore (3). A number of orally available highly potent nonsteroidal modulators were identified by modification of the substituents at 5-methylidene position.

  14. 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.

  15. Pressure-driven 4 f localized-itinerant crossover in heavy-fermion compound CeIn3: A first-principles many-body perspective

    NASA Astrophysics Data System (ADS)

    Lu, Haiyan; Huang, Li

    2016-08-01

    The localized-itinerant nature of Ce -4 f valence electrons in heavy fermion compound CeIn3 under pressure is studied thoroughly by means of the combination of density functional theory and single-site dynamical mean-field theory. The detailed evolutions of electronic structures of CeIn3, including total and partial density of states, momentum-resolved spectral functions, and valence state histograms, are calculated in a wide pressure range where the corresponding volume compression V /V0∈[0.6 ,1.0 ] (here V0 is the experimental crystal volume) at T ≅116 K. Upon increasing pressure, two strong peaks associated with the Ce -4 f states emerge near the Fermi level, and the c -f hybridization and valence state fluctuation are enhanced remarkably. Moreover, the kinetic and potential energies rise, while the occupancy, total angular momentum, and low-energy scattering rate of the Ce -4 f electrons decline with respect to pressure. All the physical observables considered here exhibit prominent kinks or fluctuations in V /V0∈[0.80 ,0.90 ] , which are probably the desired fingerprints for the Ce -4 f localized-itinerant crossover.

  16. 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.

  17. Interactions of y+LAT1 and 4F2hc in the y+l amino acid transporter complex: consequences of lysinuric protein intolerance-causing mutations.

    PubMed

    Toivonen, Minna; Tringham, Maaria; Kurko, Johanna; Terho, Perttu; Simell, Olli; Heiskanen, Kaisa M; Mykkänen, Juha

    2013-12-01

    Lysinuric protein intolerance (LPI) is an inherited aminoaciduria caused by recessive mutations in the SLC7A7 gene encoding y+L amino acid transporter 1 (y+LAT1), which combines with 4F2hc to generate an active transporter responsible for the system y+L amino acid transport. We have previously shown that the y+LAT1 proteins with point mutations are expressed in the plasma membrane, while those with frameshift mutations are retained in the cytoplasm. This finding has prompted us to study whether the difference in localization is due to the inability of the structurally altered mutant y+LAT1 proteins to heteromerize with 4F2hc. For this purpose, we utilized FACS technique to reveal fluorescence resonance energy transfer (FRET) in cells expressing wild type or LPI-mutant CFP-tagged y+LAT1 and YFP-tagged 4F2hc. The heteromerization of y+LAT1 and 4F2hc within the cell is not disrupted by any of the tested LPI mutations. In addition, the expression rate of the LPI mutant y+LAT1 proteins was significantly lower and cellular mortality was markedly increased than that of the wild type y+LAT1 in transfected samples. Our results indicate that the FACS-FRET method provides an alternative approach for screening of potential protein associations.

  18. 5 d-4 f luminescence of Nd3+, Gd3+, Er3+, Tm3+, and Ho3+ ions in crystals of alkaline earth fluorides

    NASA Astrophysics Data System (ADS)

    Radzhabov, E. A.; Prosekina, E. A.

    2011-09-01

    The vacuum ultraviolet emission spectra of alkaline-earth fluoride (CaF2, SrF2, BaF2) crystals with rare earth impurity ions (Nd, Gd, Er, Tm, Ho) have been investigated. The main luminescence bands are described well by the transitions from the lowest excited 5 d state to different 4 f levels of rare earth ions.

  19. A Green Route to a Na2FePO4F-Based Cathode for Sodium Ion Batteries of High Rate and Long Cycling Life.

    PubMed

    Deng, Xiang; Shi, Wenxiang; Sunarso, Jaka; Liu, Meilin; Shao, Zongping

    2017-05-17

    Sodium ion batteries (SIBs) are considered one of the most promising alternatives for large-scale energy storage due largely to the abundance and low cost of sodium. However, the lack of high-performance cathode materials at low cost represents a major obstacle toward broad commercialization of SIB technology. In this work, we report a green route strategy that allows cost-effective fabrication of carbon-coated Na2FePO4F cathode for SIBs. By using vitamin C as a green organic carbon source and environmentally friendly water-based polyacrylic latex as the binder, we have demonstrated that the Na2FePO4F phase in the as-derived Na2FePO4F/C electrode shows a high reversible capacity of 117 mAh g(-1) at a cycling rate of 0.1 C. More attractively, excellent rate capability is achieved while retaining outstanding cycling stability (∼85% capacity retention after 1000 charge-discharge cycles at a rate of 4 C). Further, in operando X-ray diffraction has been used to probe the evolution of phase structures during the charge-discharge process, confirming the structural robustness of the Na2FePO4F/C cathode (even when charged to 4.5 V). Accordingly, the poor initial Coulombic efficiency of some anode materials may be compensated by extracting more sodium ions from Na2FePO4F/C cathode at higher potentials (up to 4.5 V).

  20. 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

  1. 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.

  2. 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

    2016-06-03

    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.

  3. Translation initiation complex eIF4F is a therapeutic target for dual mTOR kinase inhibitors in non-Hodgkin lymphoma.

    PubMed

    Demosthenous, Christos; Han, Jing Jing; Stenson, Mary J; Maurer, Matthew J; Wellik, Linda E; Link, Brian; Hege, Kristen; Dogan, Ahmet; Sotomayor, Eduardo; Witzig, Thomas; Gupta, Mamta

    2015-04-20

    Deregulated mRNA translation has been implicated in disease development and in part is controlled by a eukaryotic initiation complex eIF4F (composed of eIF4E, eIF4G and eIF4A). We demonstrate here that the cap bound fraction from lymphoma cells was enriched with eIF4G and eIF4E indicating that lymphoma cells exist in an activated translational state. Moreover, 77% (110/142) of diffuse large B cell lymphoma tumors expressed eIF4E and this was associated with an inferior event free survival. Over-expression of wild-type eIF4E (eIF4E(WT)) but not cap-mutant eIF4E (eIF4E(cap mutant)) increased the activation of the eIF4F complex. Treatment with the active-site dual mTOR inhibitor CC214-1 reduced the level of the eIF4F complex by decreasing the cap bound fraction of eIF4G and increasing the levels of 4E-BP1. CC214-1 inhibited both the cap dependent and global protein translation. CC214-1 inhibited c-Myc, and cyclin D3 translation by decreasing polysomal fractions from lymphoma cells. Inhibition of eIF4E with shRNA further decreased the CC214-1 induced inhibition of the eIF4F complex, c-Myc, cyclin D3 translation, and colony formation. These studies demonstrate that the eIF4F complex is deregulated in aggressive lymphoma and that dual mTOR therapy has therapeutic potential in these patients.

  4. An XPS study on the impact of relative humidity on the aging of UO2 powders

    DOE PAGES

    Donald, Scott B.; Dai, Zurong R.; Davisson, M. Lee; ...

    2017-02-10

    High resolution x-ray photoemission spectroscopy (XPS) was used to characterize the chemical speciation of high purity uranium dioxide (UO2) powder samples following aging for periods of up to one year under controlled conditions with relative humidity ranging from 34% to 98%. A systematic shift to higher uranium oxidation states, and thus an increase in the mean uranium valence, was found to directly correlate with the dose of water received (i.e. the product of exposure time and relative humidity). Exposure duration was found to have a greater impact on sample aging than relative humidity. Lastly, the sample aged at 98% relativemore » humidity was found to have unique structural differences for exposure time beyond 180 days when observed by scanning electron microscopy (SEM).« less

  5. Spectral studies on sulfur poisoning of Pd/Mg6Ni by NEXAFS and XPS

    NASA Astrophysics Data System (ADS)

    Yagi, S.; Nambu, M.; Tsukada, C.; Ogawa, S.; Kutluk, G.; Namatame, H.; Taniguchi, M.

    2013-02-01

    We have studied on the hydrogen storage materials based on Mg-Ni alloy and fabricated the sample constructed with the Pd thin layer (TL) on Mg6Ni alloy substrate. The adsorption behavior of the dimethyl disulfide (DMS) molecules on the sample has been measured to reveal the sulfur poisoning of the Pd TL/Mg6Ni by means of XPS and Sulfur K-edge NEXAFS techniques. The chemisorbed DMS, methanethiolate (MT) and atomic S have been observed on the surface. Especially, it is clear that some atomic S has been oxidized by air and detected the adsorbate of the SO32- and SO42- species. During exposure to the atmosphere, most of the adsorbed DMS and MT adsorbates desorb from the Pd TL surface. We thus conclude the Pd TL might be able to prevent the hydrogen storage materials from the sulfur poisoning.

  6. 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.

  7. 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.

  8. Initial oxidation behaviors of nitride surfaces of uranium by XPS analysis

    NASA Astrophysics Data System (ADS)

    Liu, Kezhao; Luo, Lizu; Luo, Lili; Long, Zhong; Hong, Zhanglian; Yang, Hui; Wu, Sheng

    2013-09-01

    The nitride surfaces of uranium were prepared by the surface glow plasma nitriding (SGPN) and plasma immersion ion implantation (PIII) methods. The initial oxidation behaviors of modified surfaces were studied by X-ray photoelectron spectroscopy (XPS). The SGPN on the uranium surface led to a single layer of uranium sesquinitride (U2N3), while the PIII on the surface resulted in a compound layer composed of U2N3 and uranium dioxide (UO2). The oxygen covered on these modified layers led to the formation of UO2 from U2N3 and U2N3 from UN. The oxidized nitrogen species were also observed on the two types of nitriding layers, with the discussion of the N-O coaction behaviors.

  9. XPS and NMR analysis on 12CaO•7Al2O3

    NASA Astrophysics Data System (ADS)

    Pan, R. K.; Feng, S.; Tao, H. Z.

    2017-01-01

    12CaO·7Al2O3 (C12A7) glass was prepared by the melt quenching method. The glass transition temperature (T g) and the crystallization temperature (T c) of C12A7 glass are about 1050 K and 1194 K, respectively, measured by the differential scanning calorimetry (DSC). The structure of C12A7 glass was investigated by X-ray photoelectron spectroscopy (XPS) as well as magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR). Analysis shows that Al coordination number is about four in C12A7 glass, in which AlO4 tetrahedrons and bridging oxygens (BO) constitute the glass network. Ca2+ produces a few of non-bridging oxygens (NBO), which become neighbours of Al.

  10. FTIR, EPMA, Auger, and XPS analysis of impurity precipitates in CdS films

    SciTech Connect

    Webb, J.D.; Rose, D.H.; Niles, D.W.; Swartzlander, A.; Al-Jassim, M.M.

    1997-12-31

    Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Films of CdS grown using chemical bath deposition (CBD) generally yield better devices than purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this work, the authors present Fourier transform infrared (FTIR), Auger, electron microprobe (EPMA), X-ray photoelectron spectroscopic (XPS), and secondary ion mass spectroscopic (SIMS) analyses of the impurities in CBD CdS films, and show that these differ as a function of substrate type and film deposition conditions. They also show that some of these impurities exist as 10{sup 2} micron-scale precipitates.

  11. XPS analysis of lithium surface and modification of surface state for uniform deposition of lithium

    SciTech Connect

    Kanamura, K.; Shiraishi, S.; Takehara, Z.

    1995-12-31

    The surface modification of lithium deposited at various current densities in propylene carbonate containing 1.0 ml dm{sup {minus}3} LiClO{sub 4} was performed by addition of various amounts of HF into the electrolyte, in order to investigate the effect of the HF addition on the surface reaction of lithium. XPS and SEM analyses showed that the surface state of lithium was influenced by the concentration of HF and the electrodeposition current. These two parameters are related to the chemical reaction rate of the lithium surface with HF and the electrodeposition rate of lithium, respectively. The surface modification was highly effective in suppressing lithium dendrite formation when the chemical reaction rate with HF was greater than the electrochemical deposition rate of lithium.

  12. 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.

  13. An XPS study on the impact of relative humidity on the aging of UO2 powders

    NASA Astrophysics Data System (ADS)

    Donald, Scott B.; Dai, Zurong R.; Davisson, M. Lee; Jeffries, Jason R.; Nelson, Art J.

    2017-04-01

    High resolution x-ray photoemission spectroscopy (XPS) was used to characterize the chemical speciation of high purity uranium dioxide (UO2) powder samples following aging for periods of up to one year under controlled conditions with relative humidity ranging from 34% to 98%. A systematic shift to higher uranium oxidation states, and thus an increase in the mean uranium valence, was found to directly correlate with the dose of water received (i.e. the product of exposure time and relative humidity). Exposure duration was found to have a greater impact on sample aging than relative humidity. The sample aged at 98% relative humidity was found to have unique structural differences for exposure time beyond 180 days when observed by scanning electron microscopy (SEM).

  14. XPS study of PBO fiber surface modified by incorporation of hydroxyl polar groups in main chains

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Hu, Dayong; Jin, Junhong; Yang, Shenglin; Li, Guang; Jiang, Jianming

    2010-01-01

    Dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO), a modified poly(p-phenylene benzoxazole) (PBO) polymer containing double hydroxyl groups in polymer chains, was synthesized by copolymerization of 4,6-diamino resorcinol dihydrochloride (DAR), purified terephthalic acid (TA) and 2,5-dihydroxyterephthalic acid (DHTA). DHPBO fibers were prepared by dry-jet wet-spinning method. The effects of hydroxyl polar groups on the surface elemental compositions of PBO fiber were investigated by X-ray photoelectron spectroscopy (XPS). The results show that the ratio of oxygen/carbon on the surface of DHPBO fibers is higher than that on the surface of PBO fibers, which indicates the content of polar groups on the surface of DHPBO fiber increase compared with PBO fiber.

  15. XPS and XAS studies of copper(II) sorbed onto a synthetic pyrite surface.

    PubMed

    Naveau, Aude; Monteil-Rivera, Fanny; Guillon, Emmanuel; Dumonceau, Jacques

    2006-11-01

    Compounds containing copper are likely candidates to delay iodide migration in environmental media through the formation of sparingly soluble phases. Preliminary experiments showed that iodide was neither sorbed onto chalcopyrite nor by a binary system pyrite/copper(II), although significant amounts of copper were present at the pyrite surface. In the present study, spectroscopic studies (XPS, XANES and EXAFS) were thus performed to determine the nature of sorbed copper species. Although introduced as Cu(II), copper was mainly present at the oxidation state (I) on the pyrite surface suggesting a heterogeneous reduction process. Moreover, copper appeared tetrahedrally coordinated to two sulfur and two oxygen atoms onto the pyrite surface, a chemical environment, which seemingly stabilized the metal and made it unreactive towards iodide.

  16. 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.

  17. Core layering

    NASA Astrophysics Data System (ADS)

    Jacobson, S. A.; Rubie, D. C.; Hernlund, J. W.; Morbidelli, A.

    2015-12-01

    We have created a planetary accretion and differentiation model that self-consistently builds and evolves Earth's core. From this model, we show that the core grows stably stratified as the result of rising metal-silicate equilibration temperatures and pressures, which increases the concentrations of light element impurities into each newer core addition. This stable stratification would naturally resist convection and frustrate the onset of a geodynamo, however, late giant impacts could mechanically mix the distinct accreted core layers creating large homogenous regions. Within these regions, a geodynamo may operate. From this model, we interpret the difference between the planetary magnetic fields of Earth and Venus as a difference in giant impact histories. Our planetary accretion model is a numerical N-body integration of the Grand Tack scenario [1]—the most successful terrestrial planet formation model to date [2,3]. Then, we take the accretion histories of Earth-like and Venus-like planets from this model and post-process the growth of each terrestrial planet according to a well-tested planetary differentiation model [4,5]. This model fits Earth's mantle by modifying the oxygen content of the pre-cursor planetesimals and embryos as well as the conditions of metal-silicate equilibration. Other non-volatile major, minor and trace elements included in the model are assumed to be in CI chondrite proportions. The results from this model across many simulated terrestrial planet growth histories are robust. If the kinetic energy delivered by larger impacts is neglected, the core of each planet grows with a strong stable stratification that would significantly impede convection. However, if giant impact mixing is very efficient or if the impact history delivers large impacts late, than the stable stratification can be removed. [1] Walsh et al. Nature 475 (2011) [2] O'Brien et al. Icarus 223 (2014) [3] Jacobson & Morbidelli PTRSA 372 (2014) [4] Rubie et al. EPSL 301

  18. XPS studies on aluminum ions modified polyimide with the PIII technique

    SciTech Connect

    Han, Zhao Jun; Tay, Beng Kang; Ha, Peter C.T.; Sze, Jia Yin; Chua, Daniel H.C.

    2007-03-01

    Polyimide samples modified by aluminum (Al) ions produced by filtered cathodic vacuum arc (FCVA) with plasma immersion ion implantation (PIII) technique, under ambient argon and oxygen gases (flow rate Ar:O{sub 2}=2:1) were investigated by x-ray photoelectron spectroscopy (XPS). The working pressure was about 8x10{sup -4} Torr and the plasma density was estimated to be 10{sup 9} ions/cm{sup 3}. The applied bias voltages were varied from 5 to 12.5 kV but with fixed frequency at 900 Hz and duty time of 15 {mu}s. For 1 min process time, C 1s and O 1s spectra for modified samples clearly indicated that the carbonyl group (C=O) was largely destroyed by incident Al ions while Al 2p spectra suggested Al atoms remain inside polyimide matrices in the form of C-O-Al complexes. For a 5 min process time, when the ion fluence became large, both C 1s and O 1s spectra suggested a structure of aluminum oxide-mixed layer-polyimide and Al 2p spectra confirmed that most Al atoms were bonded to oxygen atoms on the top surface. These XPS results revealed the chemical bonds between implanted and deposited Al ions and polyimide matrix by using the PIII technique. The structural information can also be suggested. Furthermore in this paper, some discussions with the theoretical [the stopping and range of ions in matter (SRIM)] simulation were also mentioned in order to explore the effectiveness of Al ions irradiation on polyimide.

  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. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Reaction of Si nanopowder with water investigated by FT-IR and XPS

    NASA Astrophysics Data System (ADS)

    Imamura, Kentaro; Kobayashi, Yuki; Matsuda, Shinsuke; Akai, Tomoki; Kobayashi, Hikaru

    2017-08-01

    The initial reaction of Si nanopowder with water to generate hydrogen is investigated using FT-IR and XPS measurements. Si nanopowder is fabricated using the simple beads milling method. For HF-etched Si nanopowder, strong peaks due to Si-H and Si-H2 stretching vibrational modes and a weak shoulder peak due to Si-H3 are observed. Although no peaks due to oxide is observed in the Si 2p XPS spectrum, weak vibrational peaks due to HSiO2 and HSiO3 species are observable. The hydrogen generation rate greatly increases with pH, indicating that the reacting species is hydroxide ions (OH- ions). After the reaction, the intensities of the peaks due to SiH and SiH2 species decrease while those for HSiO, HSiO2, and HSiO3 species increase. This result demonstrates that OH- ions attack Si back-bonds, with surface Si-H bonds remaining. After initial reaction of HF-etched Si nanopowder with heavy water, vibrational peaks for SiD, SiDH, and SiDH2 appear, and then, a peak due to DSiO3 species is observed, but no peaks due to DSiO2 and DSiO species are observable. This result indicates that SiD, SiDH, and SiDH2 species are formed by substitution reactions, followed by oxidation of back-bonds to form DSiO3 species. After immersion in D2O for a day, 37% H atoms on the surface are replaced to D atoms.

  1. 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.

  2. 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.

  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. 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.

  5. A systematic review of experience of 180-W XPS GreenLight laser vaporisation of the prostate in 1640 men.

    PubMed

    Brunken, Claus; Seitz, Christian; Woo, Henry H

    2015-10-01

    To systematically review the literature regarding clinical outcomes of 180-W XPS GreenLight laser (GL) vaporisation for the treatment of lower urinary tract symptoms (LUTS) related to benign prostatic hyperplasia (BPH). Recent publications were identified in the field of 180-W GL vaporisation for the treatment of LUTS due to BPH. We searched for peer-reviewed original articles in the English language. Search items were: '180W lithium triborate laser' or '180W greenlight laser' or '180 watt lithium triborate laser' or '180 watt greenlight laser' or 'XPS greenlight laser'. In all, 30 papers published between 2012 and 2014 matched this search. Of these, 10 papers were identified dealing with consecutive cohorts of patients treated with the 180-W XPS GL RESULTS: The 10 papers included a total experience of 1640 patients. The only randomised controlled trial in this field compares 180-W with transurethral resection of the prostate (TURP). Functional outcomes and prostate volume reduction after GL vaporisation were similar to TURP. Catheterisation time and hospital stay were shorter in patients undergoing 180W XPS GL vaporisation (41 and 66 h vs 60 and 97 h, respectively). Four papers compared the 180-W XPS system to former GL devices showing increased operation time efficiency and comparable postoperative voiding results and adverse events. One paper defined the learning curve to achieve an expert level according to the speed of the procedure and the effectiveness of volume reduction was met after 120 procedures. The 180-W XPS GL offers shorter operation times than former devices. In the one randomised controlled trial comparison with TURP, volume reduction and functional results were comparable to those of TURP. Longer term studies are required. © 2014 The Authors BJU International © 2014 BJU International Published by John Wiley & Sons Ltd.

  6. Comparison of LiVPO4F to Li4Ti5O12 as anode materials for lithium-ion batteries.

    PubMed

    Ma, Rui; Shao, Lianyi; Wu, Kaiqiang; Shui, Miao; Wang, Dongjie; Pan, Jianguo; Long, Nengbing; Ren, Yuanlong; Shu, Jie

    2013-09-11

    In this paper, we reported on a comparison of LiVPO4F to Li4Ti5O12 as anode materials for lithium-ion batteries. Combined with powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, galvanostatic discharge/charge tests and in situ X-ray diffraction technologies, we explore and compare the insertion/extraction mechanisms of LiVPO4F based on the V3+/V2+/V+ redox couples and Li4Ti5O12 based on the Ti4+/Ti3+ redox couple cycled in 1.0-3.0 V and 0.0-3.0 V. The electrochemical results indicate that both LiVPO4F and Li4Ti5O12 are solid electrolyte interphase free materials in 1.0-3.0 V. The insertion/extraction mechanisms of LiVPO4F and Li4Ti5O12 are similar with each other in 1.0-3.0 V as proved by in situ X-ray diffraction. It also demonstrates that both samples possess stable structure in 0.0-3.0 V. Additionally, the electrochemical performance tests of LiVPO4F and Li4Ti5O12 indicate that both samples cycled in 0.0-3.0 V exhibit much higher capacities than those cycled in 1.0-3.0 V but display worse cycle performance. The rate performance of Li4Ti5O12 far exceeds that of LiVPO4F in the same electrochemical potential window. In particular, the capacity retention of Li4Ti5O12 cycled in 1.0-3.0 V is as high as 98.2% after 20 cycles. By contrast, Li4Ti5O12 is expected to be a candidate anode material considering its high working potential, structural zero-strain property, and excellent cycle stability and rate performance.

  7. In situ XPS study of Pd(1 1 1) oxidation. Part 1: 2D oxide formation in 10 -3 mbar O 2

    NASA Astrophysics Data System (ADS)

    Zemlyanov, Dmitry; Aszalos-Kiss, Balazs; Kleimenov, Evgueni; Teschner, Detre; Zafeiratos, Spiros; Hävecker, Michael; Knop-Gericke, Axel; Schlögl, Robert; Gabasch, Harald; Unterberger, Werner; Hayek, Konrad; Klötzer, Bernhard

    2006-03-01

    The oxidation of the Pd(1 1 1) surface was studied by in situ XPS during heating and cooling in 3 × 10 -3 mbar O 2. A number of adsorbed/dissolved oxygen species were identified by in situ XPS, such as the two dimensional surface oxide (Pd 5O 4), the supersaturated O ads layer, dissolved oxygen and the (√{67}×√{67})R 12.2° surface structure. Exposure of the Pd(1 1 1) single crystal to 3 × 10 -3 mbar O 2 at 425 K led to formation of the 2D oxide phase, which was in equilibrium with a supersaturated O ads layer. The supersaturated O ads layer was characterized by the O 1s core level peak at 530.37 eV. The 2D oxide, Pd 5O 4, was characterized by two O 1s components at 528.92 eV and 529.52 eV and by two oxygen-induced Pd 3d 5/2 components at 335.5 eV and 336.24 eV. During heating in 3 × 10 -3 mbar O 2 the supersaturated O ads layer disappeared whereas the fraction of the surface covered with the 2D oxide grew. The surface was completely covered with the 2D oxide between 600 K and 655 K. Depth profiling by photon energy variation confirmed the surface nature of the 2D oxide. The 2D oxide decomposed completely above 717 K. Diffusion of oxygen in the palladium bulk occurred at these temperatures. A substantial oxygen signal assigned to the dissolved species was detected even at 923 K. The dissolved oxygen was characterised by the O 1s core level peak at 528.98 eV. The "bulk" nature of the dissolved oxygen species was verified by depth profiling. During cooling in 3 × 10 -3 mbar O 2, the oxidised Pd 2+ species appeared at 788 K whereas the 2D oxide decomposed at 717 K during heating. The surface oxidised states exhibited an inverse hysteresis. The oxidised palladium state observed during cooling was assigned to a new oxide phase, probably the (√{67}×√{67})R 12.2° structure.

  8. Ultrathin TiO(x) films on Pt(111): a LEED, XPS, and STM investigation.

    PubMed

    Sedona, Francesco; Rizzi, Gian Andrea; Agnoli, Stefano; Llabrés i Xamena, Francesc X; Papageorgiou, Anthoula; Ostermann, Dieter; Sambi, Mauro; Finetti, Paola; Schierbaum, Klaus; Granozzi, Gaetano

    2005-12-29

    Ultrathin ordered titanium oxide films on Pt(111) surface are prepared by reactive evaporation of Ti in oxygen. By varying the Ti dose and the annealing conditions (i.e., temperature and oxygen pressure), six different long-range ordered phases are obtained. They are characterized by means of low-energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy (STM). By careful optimization of the preparative parameters, we find conditions where predominantly single phases of TiO(x), revealing distinct LEED pattern and STM images, are produced. XPS binding energy and photoelectron diffraction (XPD) data indicate that all the phases, except one (the stoichiometric rect-TiO2), are one monolayer thick and composed of a Ti-O bilayer with interfacial Ti. Atomically resolved STM images confirm that these TiO(x) phases wet the Pt surface, in contrast to rect-TiO2. This indicates their interface stabilization. At a low Ti dose (0.4 monolayer equivalents, MLE), an incommensurate kagomé-like low-density phase (k-TiO(x) phase) is observed where hexagons are sharing their vertexes. At a higher Ti dose (0.8 MLE), two denser phases are found, both characterized by a zigzag motif (z- and z'-TiO(x) phases), but with distinct rectangular unit cells. Among them, z'-TiO(x), which is obtained by annealing in ultrahigh vacuum (UHV), shows a larger unit cell. When the postannealing of the 0.8 MLE deposit is carried out at high temperatures and high oxygen partial pressures, the incommensurate nonwetting, fully oxidized rect-TiO2 is found The symmetry and lattice dimensions are almost identical with rect-VO2, observed in the system VO(x)/Pd(111). At a higher coverage (1.2 MLE), two commensurate hexagonal phases are formed, namely the w- [(square root(43) x square root(43)) R 7.6 degrees] and w'-TiO(x) phase [(7 x 7) R 21.8 degrees]. They show wagon-wheel-like structures and have slightly different lattice dimensions. Larger Ti deposits

  9. 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.

  10. Study of the absorption spectra of the 4f electron transitions of the praseodymium complex with ciprofloxacin and its analytical application.

    PubMed

    Wei, J; Naixing, W; Quanjie, M; Zhikun, S; Xiuqin, X; Fuxiang, L

    2001-08-01

    Ciprofloxacin (CPFX) is proposed as a reagent for the derivative spectrophotometric determination of praseodymium in mixed rare earths. The absorption spectra of 4f electron transitions of the praseodymium complex with CPFX was studied by normal and derivative spectrophotometry. The stoichiometry of the praseodymium-CPFX complex was calculated by the molar ratio and continuous variations methods. A ratio of Pr to CPFX of 1:3 was found. The absorption bands of the 4f electron transitions of the complex were enhanced markedly. Using the third derivative spectrum. Beer's law was obeyed up to 35 microg cm(-3) of praseodymium. The relative standard deviation is 0.62% for 14 microg cm(-3) of praseodymium. The detection and quantification limits were 0.17 and 0.56 microg cm(-3) of praseodymium, respectively. A method for the direct determination of praseodymium in mixtures of rare earths with good accuracy and selectivity is described.

  11. First-principles study on surface properties of t-LiFeSO4F: Showing a potential way to enhance electronic conductivity

    NASA Astrophysics Data System (ADS)

    Xie, Weina; Yang, Xiaoling; Lin, Yanyun; Zhuang, Weiling; Luo, Qiong

    2017-09-01

    Systematic theoretical investigation on the surface properties of t-LiFeSO4F based on the stoichiometric (1 0 0), (0 1 0), and (0 0 1) surfaces at the lowest energy termination has been performed within the GGA+U framework. The surface energies of (1 0 0), (0 1 0), and (0 0 1) surfaces are 1.10, 1.64 and 1.04 J/m2 respectively. The (1 0 0) and (0 1 0) surfaces are charge transfer insulators with band gaps of 2.92 and 1.95 eV, respectively. The predicted (0 0 1) surface exhibits metallic-like character. This study suggests that increasing the percentage of (0 0 1) surface on t-LiFeSO4F crystals is an effective solution to enhance its electronic conductivity.

  12. 4f-3d interaction and magnetic anisotropy in ThMn12-type rare-earth transition-metal compounds

    NASA Astrophysics Data System (ADS)

    de Boer, F. R.; Zhao, Z. G.; Buschow, K. H. J.

    1996-05-01

    Rare-earth (R) transition-metal (T) compounds of the R(T,M)12-type with R=Y or one of the heavy-rare-earth elements, T=Fe or Co and M=Ti, V, Mo or Si, have been studied at 4.2 K in the Amsterdam High-Field Installation in magnetic fields up to 38 T and at temperatures between 4.2 and 1000 K in other magnetometers. The 4f-3d interaction is derived from magnetization measurements on single-crystalline particles that are free to rotate in the applied fields. The stabilizing element M is shown to have a pronounced influence on the 4f-3d interaction strength in these compounds. The large variation in Curie temperatures of the Y compounds and the different types of magnetic anisotropy found in the Y compounds demonstrate that the element M plays an important role in establishing these properties as well.

  13. Three new techniques for creation of a steerable sheath, a 4F snare, and bidirectional sheath inversion using existing endovascular materials.

    PubMed

    Mallios, Alexandros; Yankovic, Willy; Boura, Benoit; Combes, Myriam

    2012-09-01

    We present three novel techniques for creation of (1) a steerable sheath, (2) a 4F snare device, and (3) dual anterograde and retrograde double-wire percutaneous transluminal angioplasty access technique using a single femoral puncture. These techniques were conceived and bench-tested in our institution, allowing the utilization of inexpensive equipment for complicated endovascular procedures. They offer (1) controlled navigation, no-touch vessel cannulation and cannulation of angulated vessels, contralateral limb of stent grafts, fenestrations, and branches; (2) a low-profile (4F external diameter) modifiable snare with the ability to expand to the size of an entire aneurysm and the ability to undo the snare in case of blockage with other endovascular material; and (3) in situ sheath inversion for concomitant anterograde and retrograde percutaneous angioplasty with a single femoral puncture.

  14. Evidence of Eu2+ 4f electrons in the valence band spectra of EuTiO3 and EuZrO3

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    We report on optical band gap and valence electronic structure of two Eu2+-based perovskites, EuTiO3 and EuZrO3 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 4f7 electron band. The O 2p band shows the features similar to those of the Ba(Sr)TiO3 perovskites except that it is shifted to higher binding energies. Appearance of the Eu2+ 4f7 band is a reason for narrowing of the optical band gap in the title compounds as compared to their Sr-based analogues.

  15. Enhanced 4f-3d interaction by Ti-doping on the magnetic properties of perovskite SmFe1-xTixO3

    NASA Astrophysics Data System (ADS)

    Zhao, Huazhi; Cao, Shixun; Huang, Ruoxiang; Ren, Wei; Yuan, Shujuan; Kang, Baojuan; Lu, Bo; Zhang, Jincang

    2013-09-01

    We report the Ti-doping effects on the total magnetization of perovskite SmFe1-xTixO3 samples with x = 0, 0.1, 0.2, and 0.3. X-ray diffraction and Raman spectroscopy studies indicate that with the increase of Ti doping concentration, the lattice parameter b decreases and the oxygen octahedron is compressed along b axis. Such lattice distortion is also reflected by the changes of antisymmetric stretching mode and symmetric stretching mode of the oxygen octahedron through Raman spectra measurement. An enhancement of the interaction between Sm-4f and Fe-3d electrons is observed due to Ti-doping. This strong interplay between Sm-4f and Fe-3d electrons weakens the total magnetization and considerably suppresses the weak ferromagnetism of Fe sublattice starting from 260 K.

  16. Diode-pumped Nd:LuAG ceramic laser on 4F3/2-4I13/2transition

    NASA Astrophysics Data System (ADS)

    Xu, Changwen; Yang, Chengdong; Zhu, Haiyong; Ye, Yanlin; Duan, Yanmin; Wei, Pengfei; Zhang, Han; Zhang, Jian; Tang, Dingyuan

    2017-09-01

    Laser operation of Nd:LuAG ceramic on the 4F3/2-4I13/2 transition has been demonstrated for the first time, to the best of our knowledge. Different output couplers are used to optimize the laser performance and the highest slope efficiency of 18.0% as well as maximum output power of 3.05 W under the pump power of 21 W was obtained. The spectral characteristics of Nd:LuAG ceramic laser is carefully studied and compared with Nd:YAG ceramic laser's. In our experiment, it has been observed that the 1338 nm wavelength is always the initial and strongest oscillating spectral line when Nd:LuAG ceramic laser operates on the 4F3/2-4I13/2 transition, even though the pump level or intra-cavity loss changes greatly, which is quite different from the case of Nd:YAG ceramic laser.

  17. 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.

  18. 1-Phenyl-1-propyne on Cu(111): TOFMS TPD, XPS, UPS, and 2PPE Studies.

    PubMed

    Sohn, Youngku; Wei, Wei; White, John M

    2007-11-20

    The bonding properties of 1-phenyl-1-propyne (PP, C6H5CCCH3) on Cu(111) at 100 K have been studied using temperature-programmed desorption (TPD), and X-ray, ultraviolet, and two-photon photoemission spectroscopies (XPS, UPS, and 2PPE). In TPD, there is no evidence for dissociation. Multilayer desorption occurs at 187 K, and monolayer desorption occurs at 320 (83.5 kJ/mol) and 390 K (102.4 kJ/mol), with the latter dominating. Based on the calibrated C(1s) XPS, the saturation monolayer coverage is one PP per four surface Cu atoms. The broad and asymmetric C(1s) intensity profile of the monolayer can be resolved into three symmetric components, with peaks at 283.6, 284.5, and 285.2 eV and intensities of 2:6:1, respectively. These are attributed, respectively, to acetylenic carbons bound to Cu, phenyl, and methyl carbons. The monolayer valence band ultraviolet photoemission spectrum profile contains four resonances attributable to PP perturbed by interactions with the Cu(111) substrate. With the exception of the highest occupied molecular orbital (HOMO) that is shifted by 0.4 eV, these are uniformly shifted by 1 eV further from the Fermi level for the multilayer. Calculated electron density plots of the occupied orbitals coupled with UPS profiles suggest a spectator role for the phenyl group and bonding to Cu via the acetylenic carbons. The adsorption of 1.0 monolayer (ML) of PP on Cu(111) lowers the work function by 0.85 eV. Using 2PPE, two unoccupied orbitals were identified at 1.0 (U1*-LUMO) and 0.6 eV (U2*-image state) below the vacuum level. A chemisorption model consistent with these spectroscopic results and the major chemisorption peak in TPD involve di-sigma-bonding of the acetylenic carbons to a pair of second-nearest neighbor surface Cu atoms (cross-bridge).

  19. 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.