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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. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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).

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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...

  19. XPS Study of Sulfonated Polyaniline.

    DTIC Science & Technology

    1991-08-07

    WORK UMaT Arlington, VA 22203-17 14 ELEMENT NO. INO. NO. CCESSION No 11. TITLE (tinclude Security Clisification) "XPS STUDY OF SULFONATED POLYANILINE ...by block nvjmhet) FlIELD GROUP $u-GOP sulfonated polyaniline , x-ray photoelectron spectroscopy O(IPS) 19. ABSTRACT (Continue on reverse if nvessary...STUDY OF SULFONATED POLYANiLINE " by J. Yue, AJ. Epstein and A.G. MacDiarrnid Published in PMSE Preprints, (In Press 1991) University of Pennsylvania

  20. 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.

  1. 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}.

  2. 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.

  3. 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

  4. 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.

  5. 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...

  6. 23 CFR 774.3 - Section 4(f) approvals.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 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...

  7. 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}

  8. 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.

  9. 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

  10. 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+ .

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  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. 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

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. Copper Causes Regiospecific Formation of C4 F8 -Containing Six-Membered Rings and their Defluorination/Aromatization to C4 F4 -Containing Rings in Triphenylene/1,4-C4 F8 I2 Reactions.

    PubMed

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

    2016-01-18

    The presence of Cu in reactions of triphenylene (TRPH) and 1,4-C4 F8 I2 at 360 °C led to regiospecific substitution of TRPH ortho C(β) atoms to form C4 F8 -containing rings, completely suppressing substitution on C(α) atoms. In addition, Cu caused selective reductive-defluorination/aromatization (RD/A) to form C4 F4 -containing aromatic rings. Without Cu, the reactions of TRPH and 1,4-C4 F8 I2 were not regiospecific and no RD/A was observed. These results, supported by DFT calculations, are the first examples of Cu-promoted 1) regiospecific perfluoroannulation, 2) preparative C-F activation, and 3) RD/A. HPLC-purified products were characterized by X-ray diffraction, low-temperature PES, and (1) H/(19) F NMR.

  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. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  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. 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.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. Doppler broadening of annihilation radiation measurements on 3d and 4f ferromagnets using polarized positrons

    NASA Astrophysics Data System (ADS)

    Kawasuso, A.; Maekawa, M.; Fukaya, Y.; Yabuuchi, A.; Mochizuki, I.

    2012-01-01

    We measured the Doppler broadening of annihilation radiation (DBAR) spectra of 3d (Fe, Co, and Ni) and 4f (Gd, Tb, and Dy) ferromagnets under a magnetic field by using spin-polarized positrons from a 68Ge-68Ga source. The results showed that the DBAR spectra of these metals have notably different magnetic-field dependences. The differences among Fe, Co, and Ni reflect that the upper minority spin bands of Fe and Co are nearly empty while those of Ni are still mostly occupied. For the rare-earth metals instead of the inner 4f electrons, 5d electrons that mediate the exchange interaction of the 4f electrons are primarily responsible for the magnetic-field effects on the DBAR spectra. Furthermore, the magnetic-field effects on the DBAR spectra of Gd, Tb, and Dy vanished above the Curie temperatures of the magnetic-phase transition for these metals.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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....

  10. 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.

  11. 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.

  12. 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 §...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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).

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Bidirectional RNA helicase activity of eucaryotic translation initiation factors 4A and 4F.

    PubMed Central

    Rozen, F; Edery, I; Meerovitch, K; Dever, T E; Merrick, W C; Sonenberg, N

    1990-01-01

    The mechanism of ribosome binding to eucaryotic mRNAs is not well understood, but it requires the participation of eucaryotic initiation factors eIF-4A, eIF-4B, and eIF-4F and the hydrolysis of ATP. Evidence has accumulated in support of a model in which these initiation factors function to unwind the 5'-proximal secondary structure in mRNA to facilitate ribosome binding. To obtain direct evidence for initiation factor-mediated RNA unwinding, we developed a simple assay to determine RNA helicase activity, and we show that eIF-4A or eIF-4F, in combination with eIF-4B, exhibits helicase activity. A striking and unprecedented feature of this activity is that it functions in a bidirectional manner. Thus, unwinding can occur either in the 5'-to-3' or 3'-to-5' direction. Unwinding in the 5'-to-3' direction by eIF-4F (the cap-binding protein complex), in conjunction with eIF-4B, was stimulated by the presence of the RNA 5' cap structure, whereas unwinding in the 3'-to-5' direction was completely cap independent. These results are discussed with respect to cap-dependent versus cap-independent mechanisms of ribosome binding to eucaryotic mRNAs. Images PMID:2304461

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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).

  8. 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.

  9. 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.

  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. 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.

  12. 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

  13. 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

  14. 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)

  15. 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

  16. 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

  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. 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}

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

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

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Ghose, S.

    1972-01-01

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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

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

    PubMed

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

    2015-09-08

    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.

  9. 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).

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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...

  9. 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...

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  14. 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.

  15. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  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. 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.

  5. 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.

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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].

  4. 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

  5. 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)

  6. 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)

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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).

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. [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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  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. [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

  10. 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.

  11. 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.

  12. 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

  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 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.

  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. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 5'-UTR mediated translational control of splicing assembly factor RNP-4F expression during development of the Drosophila central nervous system.

    PubMed

    Chen, Jing; Yang, Julianne T; Doctor, Dana L; Rawlins, Bridgette A; Shields, B Colleen; Vaughn, Jack C

    2013-10-10

    Drosophila RNP-4F is a highly conserved protein from yeast to human and functions as a spliceosome assembly factor during pre-mRNA splicing. Two major developmentally regulated rnp-4f mRNA isoforms have been described during fly development, designated "long" and "short," differing by a 177-nt tract in the 5'-UTR. This region potentially folds into a single long stable stem-loop by pairing of intron 0 and part of exon 2. Since the coding potential for the two isoforms is identical, the interesting question arises as to the functional significance of this evolutionarily-conserved 5'-UTR feature. Here we describe the effects of wild-type and mutated stem-loop on modulation of rnp-4f gene expression in embryos using a GFP reporter assay. In this work, a new GFP expression vector designated pUAS-Neostinger was constructed. The UAS-GAL4 system was utilized to trigger GFP expression using tissue-specific promoter driver fly lines. Fluorescence microscopy visualization, Western blotting and real-time qRT-PÇR were used to study and quantify GFP reporter protein and mRNA levels. A significant increase in GFP reporter protein expression due to presence of the wild-type stem-loop sequence/structure was unexpectedly observed with no concomitant increase in GFP reporter mRNA levels, showing that the 177-nt region enhancement acts posttranscriptionally. The effects of potential cis-acting elements within the stem-loop were evaluated using the reporter assay in two mutant constructs. Results of GFP reporter over-expression show that RNP-4F translational regulation is highly sensitive in the developing fly central nervous system. The potential molecular mechanism behind the observed translational enhancement is discussed.

  15. On the effect of 4f electrons on the structural characteristics of lanthanide trihalides: computational and electron diffraction study of dysprosium trichloride.

    PubMed

    Lanza, Giuseppe; Varga, Zoltán; Kolonits, Maria; Hargittai, Magdolna

    2008-02-21

    The molecular and electronic structure of dysprosium trichloride, DyCl(3), was calculated by high-level quantum chemical methods in order to learn about the effect of the partially filled 4f subshell and of the possible spin-orbit coupling on them. High-temperature electron diffraction studies of DyCl(3) were also carried out so that we could compare the computed geometry with the experimental one, after thermal corrections on the latter. Dysprosium monochloride, DyCl, and the dimer of dysprosium trichloride, Dy(2)Cl(6), were also investigated by computation. We found that the electron configuration of the 4f subshell does not influence the geometry of the trichloride monomer molecule as the ground state and first excited state molecules have the same geometry. Nonetheless, taking the 4f electrons into account in the calculation, together with the 5s and 5p electrons, is important in order to get geometrical parameters consistent with the results from experiment. Based on electron diffraction and different levels of computation, the suggested equilibrium bond length (r(e)) of DyCl(3) is 2.443(14) A, while the thermal average distance (r(g)) from electron diffraction is 2.459(11) A. The molecule is trigonal planar in equilibrium. Although the ground electronic state splits due to spin-orbit coupling, the lowering of the total electronic energy is very small (about 0.025 hartree) and the geometrical parameters are not affected. In contrast with the monomeric trichloride molecule, the bond angles of the dimer seem to be different for different electronic states, indicating the influence of the 4f electronic configuration on their structure. We carried out an anharmonic analysis of the out-of-plane vibration of the trichloride monomer and found that the vibration is considerably anharmonic at 39.5 cm(-1), compared with the 30.5 cm(-1) harmonic value.

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

    SciTech Connect

    1994-10-31

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

  17. 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.

  18. Ce 4 f electronic states of CeO1 -xFxBiS2 studied by soft x-ray photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Wakita, Takanori; Terashima, Kensei; Hamada, Takahiro; Fujiwara, Hirokazu; Minohara, Makoto; Kobayashi, Masaki; Horiba, Koji; Kumigashira, Hiroshi; Kutluk, Galif; Nagao, Masanori; Watauchi, Satoshi; Tanaka, Isao; Demura, Satoshi; Okazaki, Hiroyuki; Takano, Yoshihiko; Mizuguchi, Yoshikazu; Miura, Osuke; Okada, Kozo; Muraoka, Yuji; Yokoya, Takayoshi

    2017-02-01

    We use soft x-ray photoemission spectroscopy (SXPES) to investigate Ce 4 f electronic states of a new BiS2 layered superconductor CeO1 -xFxBiS2 , for polycrystalline and single-crystal samples. The Ce 3 d spectrum of the single crystal of nominal composition x =0.7 has no f0 component and the spectral shape closely resembles the ones observed for Ce trivalent insulating compounds, strongly implying that the CeO layer is still in an insulating state even after the F doping. The Ce 3 d -4 f resonant SXPES for both polycrystalline and single-crystal samples shows that the prominent peak is located around 1 eV below the Fermi level (EF) with negligible spectral intensity at EF. The F-concentration dependence of the valence band spectra for single crystals shows the increases of the degeneracy in energy levels and of the interaction between Ce 4 f and S 3 p states. These results give insight into the nature of the CeO1 -xFx layer and the microscopic coexistence of magnetism and superconductivity in CeO1 -xFxBiS2 .

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

    PubMed Central

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

    2016-01-01

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

  20. Synthesis, structure and electrochemical properties of LiNaCo0.5Fe0.5PO4F fluoride-phosphate

    NASA Astrophysics Data System (ADS)

    Fedotov, Stanislav S.; Kuzovchikov, Sergey M.; Khasanova, Nellie R.; Drozhzhin, Oleg A.; Filimonov, Dmitriy S.; Karakulina, Olesia M.; Hadermann, Joke; Abakumov, Artem M.; Antipov, Evgeny V.

    2016-10-01

    LiNaCo0.5Fe0.5PO4F fluoride-phosphate was synthesized via conventional solid-state and novel freeze-drying routes. The crystal structure was refined based on neutron powder diffraction (NPD) data and validated by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM). The alkali ions are ordered in LiNaCo0.5Fe0.5PO4F and the transition metals jointly occupy the same crystallographic sites. The oxidation state and oxygen coordination environment of the Fe atoms were verified by 57Fe Mössbauer spectroscopy. Electrochemical tests of the LiNaCo0.5Fe0.5PO4F cathode material demonstrated a reversible activity of the Fe3+/Fe2+ redox couple at the electrode potential near 3.4 V and minor activity of the Co3+/Co2+ redox couple over 5 V vs Li/Li+. The material exhibited the discharge capacity of more than 82% (theo.) regarding Fe3+/Fe2+ in the 2.4÷4.6 V vs Li/Li+ potential range.

  1. Ion effects on CF2 surface interactions during C3F8 and C4F8 plasma processing of Si

    NASA Astrophysics Data System (ADS)

    Martin, Ina T.; Fisher, Ellen R.

    2004-09-01

    Surface interactions of difluorocarbene (CF2) molecules were investigated using our LIF based imaging of radicals interacting with surfaces (IRIS) apparatus. LIF data of CF2 in C3F8 and C4F8 plasma molecular beams reveal that the relative densities of CF2 increase with increasing rf power and source pressure in both plasma systems. The surface reactivity of CF2 molecules during C3F8 and C4F8 plasma processing of room temperature Si substrates was also measured over a broad rf power range and at different pressures. A scatter coefficient (S) greater than one was measured for all unperturbed systems, indicating that CF2 molecules are produced at the substrate surface during film deposition. The same systems were also studied under ion-limited conditions, yielding S~1, clear indication that ions are partially responsible for CF2 surface production. Plasma ions were identified using plasma-ion mass spectrometry. These data indicate that higher levels of CxFy+ (x>1) are produced in the C4F8 plasmas. X-ray photoelectron spectroscopy analyses of treated substrates showed that amorphous fluorocarbon films were deposited during plasma processing of the substrates. A positive correlation was found between S(CF2) and film composition of FC materials deposited in both the IRIS apparatus and independent reactors.

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

    DOE PAGES

    Metzler, Dominik; Li, Chen; Engelmann, Sebastian; ...

    2015-11-11

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

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

    PubMed

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

    2012-09-26

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

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

    SciTech Connect

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

    2013-08-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  6. AFM AND XPS Characterization of Zinc-Aluminum Alloy Coatings with Attention to Surface Dross and Flow Lines

    NASA Astrophysics Data System (ADS)

    Harding, Felipe A.; Alarcon, Nelson A.; Toledo, Pedro G.

    Surfaces of various zinc-aluminum alloy (Zn-Al) coated steel samples are studied with attention to foreign surface dross by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS/ESCA). AFM topographic maps of zinc-aluminum alloy surfaces free of dross reveal the perfect nanoscale details of two kinds of dendrites: branched and globular. In all magnifications the dendrites appear smooth and, in general, very clean. XPS analysis of the extreme surface of a Zn-Al sample reveals Al, Zn, Si and O as the main components. The XPS results show no segregation or separation of phases other than those indicated by the ternary Al-Zn-Si diagram. For surfaces of Zn-Al plagued with impurities, high resolution AFM topographic maps reveal three situations: (1) areas with well-defined dendrites, relatively free of dross; (2) areas with small, millimeter-sized black spots known as dross; and (3) areas with large black stains, known as flow lines. Dendrite deformation and dross accumulation increase notably in the neighborhood, apparently clean to the naked eye, of dross or flow lines. XPS results of areas with dross and flow lines indicate unacceptable high concentration of Si and important Si phase separation. These results, in the light of AFM work, reveal that dross and flow lines are a consequence of a high local concentration of Si from high melting point silica and silicate impurities in the Zn-Al alloy source.

  7. Chemical and structural characterization of Zrsbnd Csbnd Nsbnd Ag coatings: XPS, XRD and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Calderon V, S.; Cavaleiro, A.; Carvalho, S.

    2015-08-01

    In this report Zrsbnd Csbnd Nsbnd Ag coatings produced by dual magnetron sputtering are characterized by X-ray photoelectron spectroscopy (XPS) and complemented by X-ray diffraction, scanning electron microscopy, electron-probe microanalysis and Raman spectroscopy, in order to determine the chemical bonds and phases formed during the production process. The results demonstrate the possibility of producing coatings with different silver content (0-16 at.%), in which zirconium carbonitrides (70-95 at.%), amorphous carbon nitride phases (0-16 at.%) and residual zirconium oxide phases (∼5 at.%) coexists with the metallic silver. The profile analysis evidenced a highly oxidized surface due to the affinity of Zr to form ZrO2, and silver segregation to the surface. The composition after Ar+ bombardment revealed the contribution of silver clusters and metallic silver, together with the mentioned phases that vary in content depending on the deposition parameters utilized. STEM images revealed silver nanoparticles distributed in the Zrsbnd Csbnd N matrix with sizes around 5-20 nm, as well as silver surface agglomeration with sizes <80 nm.

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  9. XPS analysis and luminescence properties of thin films deposited by the pulsed laser deposition technique

    NASA Astrophysics Data System (ADS)

    Dolo, J. J.; Swart, H. C.; Coetsee, E.; Terblans, J. J.; Ntwaeaborwa, O. M.; Dejene, B. F.

    2010-04-01

    This paper presents the effect of substrate temperature and oxygen partial pressure on the photoluminescence (PL) intensity of the Gd2O2S:Tb3 + thin films that were grown by using pulsed laser deposition (PLD). The PL intensity increased with an increase in the oxygen partial pressure and substrate temperature. The thin film deposited at an oxygen pressure of 900 mTorr and substrate temperature of 900°C was found to be the best in terms of the PL intensity of the Gd2O2S:Tb3 + emission. The main emission peak due to the 5D4-7F5 transition of Tb was measured at a wavelength of 545 nm. The stability of these thin films under prolonged electron bombardment was tested with a combination of techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and Cathodoluminescence (CL) spectroscopy. It was shown that the main reason for the degradation in luminescence intensity under electron bombardment is the formation of a non-luminescent Gd2O3 layer, with small amounts of Gd2S3, on the surface.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  12. FTIR and XPS studies of surface chemistry of pyrite in flotation

    SciTech Connect

    Leppinen, J.; Laajalehto, K.; Kartio, I.; Suoninen, E.

    1995-12-31

    Efficient separation of pyrite is of great importance for the metallurgical performance of flotation processes. Presently, separation of pyrite by flotation is becoming more and more important for reduction of sulfur in coal. In this work Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) were used to study the surface chemistry of pyrite in depression, activation and xanthate adsorption under conditions of controlled potential. Modifications of pyrite surfaces after treatment with depressants (lime, sulfur dioxide, sodium cyanide) and after activation with metal ions (Cu, Pb) were studied. The principal adsorption product identified on pyrite was dixanthogen whose formation started at about +0.15 V and +0.25 V (vs, SHE) in ethyl and amyl xanthate solutions, respectively. Copper xanthate was formed on copper(II) activated pyrite. Activation mechanism of pyrite by copper(II) salts is likely to be electrochemical where copper occurs as copper(I) on the surface of pyrite. Effective depression is achieved by sulfur dioxide and sodium cyanide. Depression at high pH is due to formation of iron(III) hydroxides. Calcium ions do not affect the electrochemistry but adsorb on pyrite and reduce the surface sites for dixanthogen adsorption.

  13. Geometrical Characterization of Adenine And Guanine on Cu(110) By NEXAFS, XPS, And DFT Calculation

    SciTech Connect

    Furukawa, M.; Yamada, T.; Katano, S.; Kawai, M.; Ogasawara, H.; Nilsson, A.; /SLAC, SSRL /Stockholm U.

    2009-04-30

    Adsorption of purine DNA bases (guanine and adenine) on Cu(1 1 0) was studied by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine-structure spectroscopy (NEXAFS), and density-functional theory (DFT) calculation. At coverages near 0.2 monolayers, Angular-resolved NEXAFS analysis revealed that adenine adsorbates lie almost flat and that guanine adsorbates are tilted up on the surface with the purine ring parallel to the atom rows of Cu(1 1 0). Referring to the previous studies on pyrimidine DNA bases [M. Furukawa, H. Fujisawa, S. Katano, H. Ogasawara, Y. Kim, T. Komeda, A. Nilsson, M. Kawai, Surf. Sci. 532-535 (2003) 261], the isomerization of DNA bases on Cu(1 1 0) was found to play an important role in the adsorption geometry. Guanine, thymine and cytosine adsorption have an amine-type nitrogen next to a carbonyl group, which is dehydrogenated into imine nitrogen on Cu(1 1 0). These bases are bonded by the inherent portion of - NH-CO - altered by conversion into enolic form and dehydrogenation. Adenine contains no CO group and is bonded to Cu(1 1 0) by participation of the inherent amine parts, resulting in nearly flatly-lying position.

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

    NASA Astrophysics Data System (ADS)

    Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  16. Amino acid-based ionic liquids: using XPS to probe the electronic environment via binding energies.

    PubMed

    Hurisso, Bitu Birru; Lovelock, Kevin R J; Licence, Peter

    2011-10-21

    Here we report the synthesis and characterisation by X-ray photoelectron spectroscopy (XPS) of eight high purity amino acid-based ionic liquids (AAILs), each containing the 1-octyl-3-methylimidazolium, [C(8)C(1)Im](+), as a standard reference cation. All expected elements were observed and the electronic environments of these elements identified. A fitting model for the carbon 1s region of the AAILs is reported; the C aliphatic component of the cation was used as an internal reference to obtain a series of accurate and reproducible binding energies. Comparisons are made between XP spectra of the eight AAILs and selected non-functionalised ionic liquids. 1-octyl-3-methylimidazolium acetate was also studied as a model of the carboxyl containing amino acid anion. The influence of anionic substituent groups on the measured binding energies of all elements is presented, and communication between anion and cation is investigated. This data is interpreted in terms of hard and soft anions and compared to the Kamlet-Taft hydrogen bond acceptor ability, β, for the ionic liquids. A linear correlation is presented which suggests that the functional side chain, or R group, of the amino acid has little impact upon the electronic environment of the charge-bearing moieties within the anions and cations studied.

  17. Iridescent Art Nouveau glass - IBA and XPS for the characterisation of thin iridescent layers

    NASA Astrophysics Data System (ADS)

    Jembrih, D.; Neelmeijer, C.; Schreiner, M.; Mäder, M.; Ebel, M.; Svagera, R.; Peev, M.

    2001-07-01

    The external proton beam of the Tandem accelerator of the Research Centre in Rossendorf/Germany was used to carry out non-destructive particle-induced X-ray emission (PIXE) particle-induced gamma-ray emission (PIGE) and Rutherford backscattering (RBS) measurements simultaneously on Art Nouveau artifacts produced around 1900 by Tiffany/USA and Loetz/Austria. These studies should proof the technology of producing an iridescent layer on a glass surface. By means of the yield ratio Y(Si-K)/ Y(Si-γ) of both characteristic X-radiation (Si-K) and γ-radiation (Si-γ) of the element silicon it could be shown that a thin top layer is present on the glass surface due to the treatment of the heated artifacts (about 500°C) with an alcoholic solution of SnCl 2[1]. Combined evaluation of the PIXE and RBS spectra resulted in a thickness of 20-300 nm for this top layer. In addition, a transition region between the iridescent layer and the bulk glass was obtained by RUMP simulations. Approximately 80% of the total amount of the Sn were found to be present in this transition layer and only 10-20% in the outermost surface region. XPS studies showed that the outermost layer consists of SnO 2. The formation of other Sn compounds in the outermost near-surface region based on Sn-Si-O during the manufacturing process can be excluded.

  18. Raman and XPS analyses of pristine and annealed N-doped double-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Sauer, Markus; Domanov, Oleg; Rohringer, Philip; Ayala, Paola; Pichler, Thomas

    2015-11-01

    N-doped single/multi-walled carbon nanotubes (CNTs) were studied for long time from synthesis to properties. However, the stability of N in the CNT lattice still needs further developments. In this work, to obtain more stable N-doped CNTs, concentric double-walled (DW) CNTs with more N were synthesized using benzylamine as C and N source. In order to test the stability of N-doped DWCNTs, high-temperature annealing in vacuum was performed. By XPS and Raman spectroscopic measurements, we found that the N-doped DWCNTs are still stable under 1500 $\\,^{\\circ}\\mathrm{C}$: the graphitic N does not change at all, the molecular N is partly removed, and the pyridinic N ratio greatly increases by more than two times. The reason could be that the N atoms from the surrounded N-contained materials combine into the CNT lattice during the annealing. Compared with the undoped DWCNTs, no Raman frequency shift was observed for the RBM, the G-band, and the G'-band of the N-doped DWCNTs.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  2. XPS and SIMS study of the surface and interface of aged C+ implanted uranium

    DOE PAGES

    Donald, Scott B.; Siekhaus, Wigbert J.; Nelson, Art J.

    2016-09-08

    X-ray photoelectron spectroscopy in combination with secondary ion mass spectrometry depth profiling were used to investigate the surface and interfacial chemistry of C+ ion implanted polycrystalline uranium subsequently oxidized in air for over 10 years at ambient temperature. The original implantation of 33 keV C+ ions into U238 with a dose of 4.3 × 1017 cm–3 produced a physically and chemically modified surface layer that was characterized and shown to initially prevent air oxidation and corrosion of the uranium after 1 year in air at ambient temperature. The aging of the surface and interfacial layers were examined by using themore » chemical shift of the U 4f, C 1s, and O 1s photoelectron lines. In addition, valence band spectra were used to explore the electronic structure of the aged carbide surface and interface layer. Moreover, the time-of-flight secondary ion mass spectrometry depth profiling results for the aged sample confirmed an oxidized uranium carbide layer over the carbide layer/U metal interface.« less

  3. Ce 4f electron in CeH2.1, CeH2.4, CeAl2, CePd3, CeRh3, and CeRu2: A photoemission study using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Peterman, D. J.; Weaver, J. H.; Croft, M.; Peterson, D. T.

    1983-01-01

    We present a photoemission study of the Ce 4f electron in materials which range from the localized, trivalent (4f1) compounds CeH2 and CeAl2 to the reportedly tetravalent (4f0) compounds CeRh3 and CeRu2. Using synchrotron radiation in the photon energy range of 10<=hν<=140 eV, we compare the valence-band emission of the Ce compounds with that of the analogous La compounds, paying particular attention to resonant behavior near the 4d-->4f transition threshold. In addition, we use the partial photoelectron yield as an indicator of the degree of 4f localization as well as occupation. We find no evidence of a change in 4f occupation across the series CeH2.1-->CeRu2. Instead, we find an increase in the width of the 4f emission and an increase in the effect of the 4f electron on the remaining band states. We conclude that the apparent valence changes in these particular compounds are due primarily to hybridization effects, in agreement with recent band-structure calculations.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  5. A single-source precursor approach to solution processed indium arsenide thin films† †Electronic supplementary information (ESI) available: Table listing selected bond lengths and angles for InAs precursor complex. Cross-sectional SEM of InAs thin film. XPS depth profile spectra of InAs thin film. Valence band XPS of InAs thin film and standard. CCDC 1477895. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6tc02293f Click here for additional data file. Click here for additional data file.

    PubMed Central

    Marchand, Peter; Sathasivam, Sanjayan; Williamson, Benjamin A. D.; Pugh, David; Bawaked, Salem M.; Basahel, Sulaiman N.; Obaid, Abdullah Y.; Scanlon, David O.; Parkin, Ivan P.

    2016-01-01

    This paper reports the synthesis of the novel single-source precursor, [{(MeInAstBu)3}2(Me2InAs(tBu)H)2] and the subsequent first report of aerosol-assisted chemical vapour deposition of InAs thin films. Owing to the use of the single-source precursor, highly crystalline and stoichiometric films were grown at a relatively low deposition temperature of 450 °C. Core level XPS depth profiling studies showed some partial oxidation of the film surface, however this was self-limiting and disappeared on etch profiles. Valence band XPS analysis matched well with the simulated density of state spectrum. Hall effect measurements performed on the films showed that the films were n-type with promising resistivity (3.6 × 10–3 Ω cm) and carrier mobility (410 cm2 V–1 s–1) values despite growth on amorphous glass substrates. PMID:27774150

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

    SciTech Connect

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

    2016-03-01

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

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

    SciTech Connect

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

    1991-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    SciTech Connect

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

    2006-06-15

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

  13. Vapor-Liquid Equilibrium in the Mixture 1,1-Difluoroethane C2H4F2 + C4H8 2-Methylpropene (EVLM1131, LB5730_E)

    NASA Astrophysics Data System (ADS)

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

    This document is part of Subvolume A 'Binary Liquid Systems of Nonelectrolytes I' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'Vapor-Liquid Equilibrium in the Mixture 1,1-Difluoroethane C2H4F2 + C4H8 2-Methylpropene (EVLM1131, LB5730_E)' providing data from direct measurement of pressure and mole fraction in vapor phase at variable mole fraction in liquid phase and constant temperature.

  14. Unusual reaction paths of SN2 nucleophile substitution reactions CH4 + H- → CH4 + H- and CH4 + F- → CH3F + H-: Quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Minyaev, Ruslan M.; Quapp, Wolfgang; Schmidt, Benjamin; Getmanskii, Ilya V.; Koval, Vitaliy V.

    2013-11-01

    Quantum chemical (CCSD(full)/6-311++G(3df,3pd), CCSD(T)(full)/6-311++G(3df,3pd)) and density function theory (B3LYP/6-311++G(3df,3pd)) calculations were performed for the SN2 nucleophile substitution reactions CH4 + H- → CH4 + H- and CH4 + F- → CH3F + H-. The calculated gradient reaction pathways for both reactions have an unusual behavior. An unusual stationary point of index 2 lies on the gradient reaction path. Using Newton trajectories for the reaction path, we can detect VRI point at which the reaction path branches.

  15. Electronic structure and 3d-4f exchange interactions in zircon-type RCrO4 oxides (R=Dy, Ho and Gd)

    NASA Astrophysics Data System (ADS)

    Ray, Avijeet; Maitra, Tulika

    2015-06-01

    Using first principles density functional theory (DFT) calculations within GGA and GGA+U approximations we studied both ferromagnetic (FM) and antiferromagnetic (AFM) phases of zircon type RCrO4 (R= Dy, Ho, Gd) oxides. We estimated and compared the 3d-4f exchange interaction strengths J between the nearest neighbor R3+ and Cr5+ ions for R=Dy, Gd. Our results predict that DyCrO4, GdCrO4 and HoCrO4 have ferromagnetic ground state which is consistent with experimental observations.

  16. High-Magnetic-Field Effect on Interplay between Sm 4f and Mn 3d Moments in SmMnO3

    NASA Astrophysics Data System (ADS)

    Iyama, Ayato; Jung, Jong-Suck; Choi, Eun Sang; Hwang, Jungmin; Kimura, Tsuyoshi

    2012-01-01

    Measurements of magnetization and dielectric constant were carried out in static magnetic fields up to 35 T for an N-type ferrimagnetic SmMnO3 with the compensation temperature Tcomp = 9.4 K. In-field data exhibit a first-order-like transition at around Tcomp. The temperature profiles of the magnetization around the transition point show different behaviors between the data taken in magnetic fields whose energy is below and above the magnitude of the interaction between Sm 4f and Mn 3d moments. We interpret that the observed transition results from keen competition among thermal energy, the Zeeman energy, and the f--d interaction.

  17. Identification of the predicted 5s-4f level crossing optical lines with applications to metrology and searches for the variation of fundamental constants.

    PubMed

    Windberger, A; Crespo López-Urrutia, J R; Bekker, H; Oreshkina, N S; Berengut, J C; Bock, V; Borschevsky, A; Dzuba, V A; Eliav, E; Harman, Z; Kaldor, U; Kaul, S; Safronova, U I; Flambaum, V V; Keitel, C H; Schmidt, P O; Ullrich, J; Versolato, O O

    2015-04-17

    We measure optical spectra of Nd-like W, Re, Os, Ir, and Pt ions of particular interest for studies of a possibly varying fine-structure constant. Exploiting characteristic energy scalings we identify the strongest lines, confirm the predicted 5s-4f level crossing, and benchmark advanced calculations. We infer two possible values for optical M2/E3 and E1 transitions in Ir^{17+} that have the highest predicted sensitivity to a variation of the fine-structure constant among stable atomic systems. Furthermore, we determine the energies of proposed frequency standards in Hf^{12+} and W^{14+}.

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  19. Variation of CH Stretch Frequencies with CH_4 Orientation in the CH_4 - F^- Complex: Multiple Resonances as Vibrational Conical Intersections

    NASA Astrophysics Data System (ADS)

    Thapaliya, Bishnu P.; Perry, David S.

    2016-06-01

    In the CH_4 - F^- complex, an adiabatic separation of the CH stretch frequencies from the CH_4 orientational coordinates allows the calculation of the four adiabatic CH stretch surfaces. These ab initio calculations reveal (i) a large variation of CH stretch frequencies (> 100 wn) in the orientational space and (ii) the existence of four symmetrically equivalent sets of vibrational conical intersections (CIs). Two sets of symmetry-allowed CIs are identified in addition to the symmetry-required CIs at the front- and back-side C3v geometries. These results have implications for the evolution of excited CH vibrations in methane during its approach to a potentially reactive surface.

  20. Total electron-scattering cross sections for CHF3, C2F6, C3F8, and c-C4F8

    NASA Astrophysics Data System (ADS)

    Sanabia, Jason E.; Cooper, Gregory D.; Tossell, John A.; Moore, John H.

    1998-01-01

    The total electron-scattering cross section has been measured for 0-20 eV electrons incident upon CHF3, C2F6, C3F8, and cyclo-C4F8. The cross sections all have a broad maximum for electron energies near 9 eV, with more or less sharper peaks attributed to temporary-negative ion resonances at lower energies. For the linear molecules a resonance in the 3-6 eV range is associated with electron capture into the lowest unoccupied orbital. The shape of the cross section for the cyclic compound implies a stable ground-state negative ion.

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

    SciTech Connect

    Ray, Avijeet Maitra, Tulika

    2015-06-24

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

  2. XPS and NEXAFS studies of VUV/O₃-treated aromatic polyurea and its application to microchip electrophoresis.

    PubMed

    Shinohara, H; Nakahara, A; Kitagawa, F; Takahashi, Y; Otsuka, K; Shoji, S; Ohara, O; Mizuno, J

    2011-12-01

    In this study, the authors performed X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) studies of vacuum ultraviolet (VUV)/O₃-treated aromatic polyurea films to investigate their treatment effects. XPS and NEXAFS spectra indicate that the benzene ring was cleaved after treatment and that carboxyl, hydroxyl, ketone and aldehyde groups were formed at the cleaved sites. The VUV/O₃-treated polyurea film was applied to a polymethylmethacrylate (PMMA) microchip for microchip electrophoresis (MCE) of bovine serum albumin (BSA). Fast electro-osmotic mobility of 4.6×10(-4) cm²/V/s as well as reduction of the BSA adhesion was achieved. This functional surface is useful for high-speed MCE analysis.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  5. XPS identification of surface-initiated polymerisation during monomer transfer moulding of poly(ɛ-caprolactone)/Bioglass ® fibre composite

    NASA Astrophysics Data System (ADS)

    Jiang, G.; Walker, G. S.; Jones, I. A.; Rudd, C. D.

    2005-12-01

    In this work, X-ray photoelectron spectroscopy (XPS) was demonstrated to be a useful method to characterise surface-initiated polymerisation. Both E-glass fibre and Bioglass ® fibre were treated using 3-aminopropyltrimethoxysilane (and propyltrimethoxysilane as a control) and then they were used as a reinforcement, respectively, in monomer transfer moulding to prepare poly(ɛ-caprolactone)/glass fibre composites with stannous octoate as the catalyst for ɛ-caprolactone polymerisation. The fibre was extracted and then analysed using XPS to probe the presence of PCL chemically bonded to the glass fibre surface. Both tin and PCL were detected on the surface of the fibres sized with 3-aminopropyltrimethoxysilane, confirming surface-initiated polymerisation of ɛ-caprolactone.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  7. Surface and bulk investigation of ZSM5 and Al-MCM-41 usingsynchrotron XPS, XANES, and hexane cracking

    SciTech Connect

    Jalil, P.A.; Kariapper, M.S.; Faiz, Z.; Tabet, N.; Hamdan, N.M.; Diaz, J.; Hussain, Z.

    2005-05-12

    We present a comparative study of ZSM5 and Al-MCM-41 catalysts using spectroscopic and chemical techniques. The analysis of conventional and synchrotron XPS spectra of these catalysts reveals the presence of a topmost surface-related Si peak in addition to the bulk peak. XANES results suggest structural modification upon heating Al-MCM-41 at 500 C. Depth-resolved XPS data show Al depletion from the surface of Al-MCM-41 in contrast to surface enrichment of Al in ZSM5. These surface modifications could be one of the reasons for the weak acidity of Al-MCM-41 in chemical reactions such as hexane cracking at different temperatures.

  8. Surface and bulk investigation of ZSM5 and Al-MCM-41 usingsynchrotron XPS, XANES, and hexane cracking

    SciTech Connect

    Jalil, P.A.; Kariapper, M.S.; Faiz, Z.; Tabet, N.; Hamdan, N.M.; Diaz, J.; Hussain, Z.

    2005-05-12

    We present a comparative study of ZSM5 and Al-MCM-41 catalysts using spectroscopic and chemical techniques. The analysis of conventional and synchrotron XPS spectra of these catalysts reveals the presence of a topmost surface-related Si peak in addition to the bulkpeak. XANES results suggest structural modification upon heating Al-MCM-41 at 500 C. Depth-resolved XPS data show Al depletion from the surface of Al-MCM-41 in contrast to surface enrichment of Al in ZSM5. These surface modifications could be one of the reasons for the weak acidity of Al-MCM-41 in chemical reactions such as hexane cracking at different temperatures.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  10. An XPS (X-Ray Photoelectron Spectroscopy) Study of the Composition of Thin Polyimide Films Formed by Vapor Deposition.

    DTIC Science & Technology

    1987-07-15

    1985) 2857. 13. B. D. Silverman, J. W. Bartha, J. G. Clabes, P. S Ho and A. R. Rossi, J. Polym . Sci. Part A 24 (1986) 3325. 14. E. Cartier , P. Pfluger...Benzenetetracarboxylic anhydride (PMDA), imidization, polymer , in situ, X-ray Photoelectron Spectroscopy (XPS),Cu(111) 20. ABSTRACT (Continue an...ODA) and 1,2,4,5 Benzenetetracarboxylic anhydride (PMDA). The imidization reaction leading to polymer formation was followed in situ with X-ray

  11. IL-6- and NGF-induced rapid control of protein synthesis and nociceptive plasticity via convergent signaling to the eIF4F complex

    PubMed Central

    Melemedjian, Ohannes K.; Asiedu, Marina N.; Tillu, Dipti V.; Peebles, Katherine A.; Yan, Jin; Ertz, Natalie; Dussor, Gregory O.; Price, Theodore J.

    2010-01-01

    Despite the emergence of translational control pathways as mediators of nociceptive sensitization, effector molecules and mechanisms responsible for modulating activity in these pathways in pain conditions are largely unknown. We demonstrate that two major algogens, the cytokine interleukin 6 (IL-6) and the neurotrophin nerve growth factor (NGF), which are intimately linked to nociceptive plasticity across preclinical models and human pain conditions, signal primarily through two distinct pathways to enhance translation in sensory neurons by converging onto the eukaryotic initiation factor (eIF) eIF4F complex. We directly demonstrate that the net result of IL-6 and NGF signaling is an enhancement of eIF4F complex formation and an induction of nascent protein synthesis in primary afferent neurons and their axons. Moreover, IL-6 and NGF induced mechanical nociceptive plasticity is blocked by inhibitors of general and cap-dependent protein synthesis. These results establish IL-6- and NGF-mediated cap-dependent translation of local proteins as a new model for nociceptive plasticity. PMID:21068317

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

    PubMed

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

    2014-05-01

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

  13. Efficient synthetic strategy to construct three-dimensional 4f-5d networks using neutral two-dimensional layers as building blocks.

    PubMed

    Zhou, Hu; Yuan, Ai-Hua; Qian, Su-Yan; Song, You; Diao, Guo-Wang

    2010-07-05

    The reaction of neutral two-dimensional (2D) layer Tb(H(2)O)(5)W(CN)(8) with pyrazine in the acetonitrile solution has led to a 3D bimetallic complex, Tb(H(2)O)(4)(pyrazine)(0.5)W(CN)(8) (1). In the structure of 1, the eight-coordinated W center adopts a slightly distorted dodecahedron, while the Tb center exhibits a nine-coordinated slightly distorted tricapped trigonal prism. The Tb(3+) atoms and the [W(CN)(8)](3-) units are linked in alternating fashion in the ab crystallographic plane, resulting in an infinite 2D corrugated layers. The linear bis-monodentate pyrazine ligands acting as pillars link adjacent layers along the c axis to form an extended 3D open framework. The possible formation mechanism is proposed, and the temperature has played a crucial role for the formation of 1. Magnetic measurements revealed the presence of ferromagnetic interaction between Tb(III) and W(V) centers. 1 marks the first structural pattern using the neutral 2D layer as building block and the first 3D complex with Ln(III)-[W(V)(CN)](8) found in octacyanometallate-based system. Such a novel and effective building-block methodology will provide a new attractive path forward in developing functionalities of 3D 4f-5d system and may provide an opportunity to obtain 3D magnet in 4f-5d assembly.

  14. Anomalous local magnetism in the 4 f-localized ferromagnets CeRu2X2B (X = Al, Ga) revealed by using ZF-μSR

    NASA Astrophysics Data System (ADS)

    Lee, Wonjun; Choi, Kwang-Yong; Yoon, Sungwon; Suh, Byoung Jin; Jang, Zeehoon; Biswas, P. K.; Baumbach, Ryan E.; Bauer, Eric D.

    2016-05-01

    We report zero-field muon spin relaxation/rotation (ZF-μSR) measurements on the 4f-localized ferromagnets CeRu2X2B (X = Al, Ga) with Ising-type anisotropy. Our ZF-μSR spectra of CeRu2Ga2B with a Curie temperature at T C = 16.3 K show a well-defined muon procession at temperatures below T C . The extracted critical exponent of β = 0.533 is close to the mean-field value of β = 0.5. On the other hand, the isomorphic CeRu2Al2B exhibits an intriguing evolution of the ZF-μSR spectrum through a spin density wave/ferromagnetic transition at T C = 12.8 K with a subsequent magnetic anomaly at T* = 6 K. Strikingly, the muon frequency decreases upon cooling to temperatures below T C and can be no longer resolved at temperatures below T*. At the same time, the muon relaxation rate increases continuously at temperatures below T C . These give an indication of the development of an inhomogeneous and dynamic ferromagnetic state. The contrasting ferromagnetism between CeRu2Ga2B and CeRu2Al2B evidences that a certain type of intrinsic/extrinsic perturbation, for example, exchange frustration and defects/impurities, can exert a drastic impact on the local magnetic properties in a family of 4 f-localized magnetic materials with frustration.

  15. Vaccinia Virus Protein Synthesis Has a Low Requirement for the Intact Translation Initiation Factor eIF4F, the Cap-Binding Complex, within Infected Cells

    PubMed Central

    Mulder, Jacqueline; Robertson, Morwenna E. M.; Seamons, Rachael A.; Belsham, Graham J.

    1998-01-01

    The role of the cap-binding complex, eIF4F, in the translation of vaccinia virus mRNAs has been analyzed within infected cells. Plasmid DNAs, which express dicistronic mRNAs containing a picornavirus internal ribosome entry site, produced within vaccinia virus-infected cells both β-glucuronidase and a cell surface-targeted single-chain antibody (sFv). Cells expressing sFv were selected from nonexpressing cells, enabling analysis of protein synthesis specifically within the transfected cells. Coexpression of poliovirus 2A or foot-and-mouth disease virus Lb proteases, which cleaved translation initiation factor eIF4G, greatly inhibited cap-dependent protein (β-glucuronidase) synthesis. Under these conditions, internal ribosome entry site-directed expression of sFv continued and cell selection was maintained. Furthermore, vaccinia virus protein synthesis persisted in the selected cells containing cleaved eIF4G. Thus, late vaccinia virus protein synthesis has a low requirement for the intact cap-binding complex eIF4F. This may be attributed to the short unstructured 5′ noncoding regions of the vaccinia virus mRNAs, possibly aided by the presence of poly(A) at both 5′ and 3′ termini. PMID:9765426

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

    SciTech Connect

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

    2014-03-15

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

  17. Comparison of pulsed and downstream deposition of fluorocarbon materials from C3F8 and c-C4F8 plasmas

    NASA Astrophysics Data System (ADS)

    Martin, Ina T.; Malkov, Galiya Sh.; Butoi, Carmen I.; Fisher, Ellen R.

    2004-03-01

    Materials deposited in continuous wave (cw) and pulsed low-pressure octafluoropropane (C3F8) and octafluorocyclobutane (c-C4F8) plasmas were characterized using Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy, static contact angle measurements, spectroscopic ellipsometry, and scanning electron microscopy (SEM). Fluorocarbon (FC) materials deposited in pulsed plasmas were less crosslinked than those deposited in cw plasmas with equivalent input powers. Within each system, higher F/C ratio materials were deposited by lowering the plasma input power/duty cycle. Using downstream depositions had a similar effect on film composition, but also resulted in decreased deposition rates. SEM analysis showed that decreases in the flexibility of the fluorocarbon films were correlated with increases in the percent of crosslinking. Additionally, the smoothness of the film surfaces suggests that polymerization processes occur on the substrate surface. Overall, films deposited in C4F8 plasmas were more crosslinked and less flexible than those deposited in C3F8 plasmas under the same conditions. The composition of the deposited FC films is correlated to the nature and relative concentrations of nascent ions previously measured in these plasma systems using plasma ion mass spectrometry. .

  18. XPS Observations of Crystal Field Splitting in TiO2 Thin Films in Quantum Confinement Approach

    NASA Astrophysics Data System (ADS)

    Sushkova, Natalya

    2015-03-01

    Transition metal oxides attract increased interest due to amazing electrical and magnetic properties and their outstanding applications designated by relative d-band redistributions that are shifted in such a way that narrow bands arranged by localized electrons are situated in the vicinity of EF. Different kinds of lattice distortions caused by doping and/or quantum size confinement of TM oxides are assigned to remarkable phenomenon Mott metal-insulator transitions, when mutual metal-oxide orbital arrangement changes dramatically. There is a widespread consensus that strong electron correlations are responsible for that change and magnetic excitation is one of manifestations of these correlations. Here we are presenting XPS study of titanium dioxide nanocrystal formations on silicon substrate with native oxide. The dynamic changes in XPS spectra were used for analysis of TiO2 thin films with mass thicknesses up to 2 monolayers formed by redox reactions of sputtered Ti on Si(100) substrate with native oxide implemented in situ under UHV conditions. XPS spectra evolution, as a traditional source of information on phase composition, was complemented by the possibility to estimate the morphology and crystal field splitting of formed precipitates. Intensity fluctuations observed for O1s, Si 2p, Ti2p spectra were accompanied by crystal field splitting in Ti2p and on second derivatives of O1s. These fluctuations were followed by noticeable changes in the vicinity of band gap indicating possible Mott metal-insulator transitions.

  19. A quantitative model and the experimental evaluation of the liquid fuel layer for the downward flame spread of XPS foam.

    PubMed

    Luo, Shengfeng; Xie, Qiyuan; Tang, Xinyi; Qiu, Rong; Yang, Yun

    2017-05-05

    The objective of this work is to investigate the distinctive mechanisms of downward flame spread for XPS foam. It was physically considered as a moving down of narrow pool fire instead of downward surface flame spread for normal solids. A method was developed to quantitatively analyze the accumulated liquid fuel based on the experimental measurement of locations of flame tips and burning rates. The results surprisingly showed that about 80% of the generated hot liquid fuel remained in the pool fire during a certain period. Most of the consumed solid XPS foam didn't really burn away but transformed as the liquid fuel in the downward moving pool fire, which might be an important promotion for the fast fire development. The results also indicated that the dripping propensity of the hot liquid fuel depends on the total amount of the hot liquid accumulated in the pool fire. The leading point of the flame front curve might be the breach of the accumulated hot liquid fuel if it is enough for dripping. Finally, it is suggested that horizontal noncombustible barriers for preventing the accumulation and dripping of liquid fuel are helpful for vertical confining of XPS fire.

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

    SciTech Connect

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

    2015-09-15

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

  1. Drying methods for XPS analysis of PureVision™, Focus ® Night&Day™ and conventional hydrogel contact lenses

    NASA Astrophysics Data System (ADS)

    Karlgard, Caroline C. S.; Sarkar, Dilip K.; Jones, Lyndon W.; Moresoli, Christine; Leung, K. T.

    2004-05-01

    The surface composition of hydrogel contact lenses that contain silicon-based monomers, PureVision™ (balafilcon A) and Focus ® Night&Day™ (lotrafilcon A), were investigated by X-ray photoelectron spectroscopy (XPS). Conventional and daily disposable hydrogel lenses based on hydroxyethyl methacrylate (HEMA) were also studied, with the commonly prescribed 1-day Acuvue ® lens (etafilcon A) used as a control. All the lenses were pre-washed and dehydrated by three different methods, including drying in air, drying in nitrogen or freezing with subsequent freeze-drying, before the XPS analysis. The lenses dried in air had more impurities on the surface, and the lenses that were freeze-dried lost transparency, suggesting that drying lenses in nitrogen is the preferred preparation method for XPS analysis. Surface compositions for all lens materials were obtained and this data can be used as a control/base-value for future analysis of the interactions of soft contact lens materials with chemicals such as drugs or tear components.

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

    NASA Technical Reports Server (NTRS)

    Lee, Myung; Rooney, William; Whiteside, James

    1992-01-01

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

  3. Study of the influence of the acrylic acid plasma parameters on silicon and polyurethane substrates using XPS and AFM

    NASA Astrophysics Data System (ADS)

    Vilani, C.; Weibel, D. E.; Zamora, R. R. M.; Habert, A. C.; Achete, C. A.

    2007-10-01

    XPS and AFM have been used to investigate surface modifications produced by acrylic acid (AA) vapor plasma treatment of silicon (Si)(1 0 0) substrates and polyurethanes (PUs) membranes. XPS analyses of Si and PUs treated substrates at low plasma power (5-20 W) revealed the formation of a thin film on the surfaces, which chemically resembles the poly(acrylic acid) film conventionally synthesised. No signal of the Si substrate could be seen under these low plasma power applications on silicon. However, when the plasma power is higher than 30 W one can clearly see XPS silicon signatures. AFM measurements of silicon substrates treated with AA plasma at low power (5-20 W) showed the formation of a thin polymer film of about 220-55 nm thickness. Further, applications of high plasma power (30-100 W) displayed a marked difference from low plasma modifications and it was found sputtering of the silicon substrate. Pervaporation results of AA plasma treated PUs membranes revealed that the selectivity for the separation of methanol from methyl- t-butyl ether is higher at 100 W and 1 min treatment time, than the other conditions studied. This last finding is discussed concerning the surface modifications produced on plasma treated silicon substrates and PU membranes.

  4. Use of XPS to clarify the Hall coefficient sign variation in thin niobium layers buried in silicon

    NASA Astrophysics Data System (ADS)

    Demchenko, Iraida N.; Lisowski, Wojciech; Syryanyy, Yevgen; Melikhov, Yevgen; Zaytseva, Iryna; Konstantynov, Pavlo; Chernyshova, Maryna; Cieplak, Marta Z.

    2017-03-01

    Si/Nb/Si trilayers formed with 9.5 and 1.3 nm thick niobium layer buried in amorphous silicon were prepared by magnetron sputtering and studied using XPS depth-profile techniques in order to investigate the change of Hall coefficient sign with thickness. The analysis of high-resolution (HR) XPS spectra revealed that the thicker layer sample has sharp top interface and metallic phase of niobium, thus holes dominate the transport. In contrast, the analysis indicates that the thinner layer sample has a Nb-rich mixed alloy formation at the top interface. The authors suggest that the main effect leading to a change of sign of the Hall coefficient for the thinner layer sample (which is negative contrary to the positive sign for the thicker layer sample) may be related to strong boundary scattering enhanced by the presence of silicon ions in the layer close to the interface/s. The depth-profile reconstruction was performed by SESSA software tool confirming that it can be reliably used for quantitative analysis/interpretation of experimental XPS data.

  5. Elastic and inelastic contributions to the XPS photoelectron diffraction patterns of Ni(100) and NiO(100)

    NASA Astrophysics Data System (ADS)

    Steiner, P.; Straub, Th.; Reinert, Fr.; Zimmermann, R.; Hüfner, S.

    1993-07-01

    XPS spectra of Ni(100) and NiO(100) single crystals, measured as a function of the polar angle in the [100]-[010] emission plane, are successfully decomposed into their elastic (intrinsic spectrum) and inelastic contributions using the background subtraction procedure as proposed by Tougaard et al. [Phys. Rev. B 25 (1981) 4452; Surf. Interface Anal. 11 (1988) 453; J. Electron Spectrosc. Relat. Phenom. 52 (1990) 243], with an electron energy loss function deduced from experimental electron energy loss spectra. The inelastic background correction factor shows a diffraction pattern which anticorrelates nearly linearly to the photoelectron diffraction pattern of the intrinsic spectrum, that is its maxima and minima coincide with the minima and maxima of the latter. This behaviour can be described by a simple model, based on heuristic arguments on inelastic and elastic losses and "defocusing" due to multiple scattering along densely packed rows of atoms in the lattice. The consequence of different background subtraction procedures on the shape of the XPS diffraction pattern and for the quantification of XPS data is discussed.

  6. Spectroscopic characterization of the isolated SF6- and C4F8- anions: observation of very long harmonic progressions in symmetric deformation modes upon photodetachment.

    PubMed

    Bopp, Joseph C; Roscioli, Joseph R; Johnson, Mark A; Miller, Thomas M; Viggiano, A A; Villano, Stephanie M; Wren, Scott W; Lineberger, W Carl

    2007-02-22

    Spectroscopic studies of the SF6- and c-C4F8- anions are reported to provide experimental benchmarks for theoretical predictions of their structures and electron binding energies. The photoelectron spectrum of SF6- is dominated by a long progression in the S-F stretching mode, with an envelope consistent with theoretical predictions that the anion preserves the Oh symmetry of the neutral, but has a longer S-F bond length. This main progression occurs with an unexpectedly strong contribution from a second mode, however, whose characteristic energy does not correspond to any of the neutral SF6 fundamental vibrations in its ground electronic state. The resulting doublet pattern is evident when the bare ion is prepared with low internal energy content (i.e., using N2 carrier gas in a free jet or liquid nitrogen-cooling in a flowing afterglow) but is much better resolved in the spectrum of the SF6-.Ar complex. The infrared predissociation spectrum of SF6-.Ar consists of a strong band at 683(5) cm(-1), which we assign to the nu3 (t1u) fundamental, the same mode that yields the strong 948 cm(-1) infrared transition in neutral SF6. One qualitatively interesting aspect of the SF6- behavior is the simple structure of its photoelectron spectrum, which displays uncluttered, harmonic bands in an energy region where the neutral molecule contains about 2 eV of vibrational excitation. We explore this effect further in the c-C4F8- anion, which also presents a system that is calculated to undergo large, symmetrical distortion upon electron attachment to the neutral. The photoelectron spectrum of this species is dominated by a long, single vibrational progression, this time involving the symmetric ring-breathing mode. Like the SF6- case, the c-C4F8- spectrum is remarkably isolated and harmonic in spite of the significant internal excitation of a relatively complex molecular framework. Both these perfluorinated anions thus share the property that the symmetrical deformation of the

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

    PubMed Central

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

    2015-01-01

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

  8. Core-core and core-valence correlation

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    SciTech Connect

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

    2008-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  12. Modification of magnetic anisotropy through 3d-4f coupling in La0.75Pr0.25Co2P2

    NASA Astrophysics Data System (ADS)

    Kovnir, Kirill; Thompson, Corey M.; Garlea, V. Ovidiu; Haskel, Daniel; Polyanskii, Anatolii A.; Zhou, Haidong; Shatruk, Michael

    2013-09-01

    Magnetic behavior of La0.75Pr0.25Co2P2 was investigated by a combination of magnetic measurements, magneto-optical imaging, neutron diffraction, and x-ray absorption spectroscopy, including x-ray magnetic circular dichroism. The material crystallizes in the ThCr2Si2 structure type and exhibits three consecutive magnetic phase transitions. At 167 K, the Co magnetic moments order ferromagnetically in the ab plane of the tetragonal crystal structure. At 66 K, a ferromagnetic ordering of Pr(4f) moments parallel to the c axis causes a rotation of the Co(3d) moments towards the c axis in the direction opposite to the Pr moments, thus forming a noncollinear ferrimagnetically ordered structure and switching the direction of the total magnetization from the ab plane to the c axis. The third magnetic transition observed at 35 K is likely associated with the establishment of the collinear ferrimagnetic order along the c axis.

  13. Phase retrieval via spatial light modulator phase modulation in 4f optical setup: numerical inverse imaging with sparse regularization for phase and amplitude.

    PubMed

    Katkovnik, Vladimir; Astola, Jaakko

    2012-01-01

    The 4f optical setup is considered with a wave field modulation by a spatial light modulator located in the focal plane of the first lens. Phase as well as amplitude of the wave field are reconstructed from noisy multiple-intensity observations. The reconstruction is optimal due to a constrained maximum likelihood formulation of the problem. The proposed algorithm is iterative with decoupling of the inverse of the forward propagation of the wave field and the filtering of phase and amplitude. The sparse modeling of phase and amplitude enables the advanced high-accuracy filtering and sharp imaging of the complex-valued wave field. Artifacts typical for the conventional algorithms (wiggles, ringing, waves, etc.) and attributed to optical diffraction can be suppressed by the proposed algorithm.

  14. Dissociation Cross Sections for C2F6, c-C4F8, C3F8, CHF3, and TEOS

    NASA Astrophysics Data System (ADS)

    Morgan, W. L.

    1999-10-01

    Extensive use is made of beam measurements, ab initio calculations, and electron swarm measurements in deriving total cross sections for dissociation of C_2F_6, c-C_4F_8, C_3F_8, CHF_3, and TEOS into neutral fragments. Use is made of a numerical optimization algorithm for scaling measured or computed cross sections and manipulating model cross sections in order to satisfy the measured electron transport data. These are molecules that are important in plasma processing because they readily dissociate into reactive radical fragments. Although swarm analyses cannot tell us what the specific radical fragments are, they can provide an accurate estimate of the cross section and, hence, rate coefficient for dissociation. Further details can be found on the KR&S Web site.

  15. An unusual 2p-3d-4f heterometallic coordination polymer featuring Ln8Na and Cu8I clusters as nodes

    NASA Astrophysics Data System (ADS)

    Zhao, Mingjuan; Chen, Shimin; Huang, Yutian; Dan, Youmeng

    2017-01-01

    A new cluster-based three-dimensional 2p-3d-4f heterometallic framework {[Ho8Na(OH)6Cu16I2(CPT)24](NO3)9(H2O)6(CH3CN)18}n (1, HCPT = 4-(4-carboxyphenyl)-1,2,4 triazole) has been prepared under solvothermal condition by using a custom-designed bifunctional organic ligand. The single-crystal structure analysis reveals that this framework features novel Ln8Na and Cu8I clusters as nodes, these nodes are further connected by the CPT ligands to give rise to a (6,14)-connected network. The magnetic property of this framework has also been investigated.

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

    DOE PAGES

    Lukens, Wayne W.; Speldrich, Manfred; Yang, Ping; ...

    2016-05-31

    The electronic structures of 4f3/5f3 Cp"3M and Cp"3M·alkylisocyanide complexes, where Cp" is 1,3-bis-(trimethylsilyl)cyclopentadienyl, are explored with a focus on the splitting of the f-orbitals, which provides information about the strengths of the metal–ligand interactions. While the f-orbital splitting in many lanthanide complexes has been reported in detail, experimental determination of the f-orbital splitting in actinide complexes remains rare in systems other than halide and oxide compounds, since the experimental approach, crystal field analysis, is generally significantly more difficult for actinide complexes than for lanthanide complexes. In this study, a set of analogous neodymium(III) and uranium(III) tris-cyclopentadienyl complexes and their isocyanidemore » adducts was characterized by electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility. The crystal field model was parameterized by combined fitting of EPR and susceptibility data, yielding an accurate description of f-orbital splitting. The isocyanide derivatives were also studied using density functional theory, resulting in f-orbital splitting that is consistent with crystal field fitting, and by multi-reference wavefunction calculations that support the electronic structure analysis derived from the crystal-field calculations. The results highlight that the 5f-orbitals, but not the 4f-orbitals, are significantly involved in bonding to the isocyanide ligands. The main interaction between isocyanide ligand and the metal center is a σ-bond, with additional 5f to π* donation for the uranium complexes. As a result, while interaction with the isocyanide π*-orbitals lowers the energies of the 5fxz2 and 5fyz2-orbitals, spin–orbit coupling greatly reduces the population of 5fxz2 and 5fyz2 in the ground state.« less

  17. de Haas–van Alphen study of role of 4f electrons in antiferromagnetic CeZn11 as compared to its nonmagnetic analog LaZn11

    DOE PAGES

    Blake, S. F.; Hodovanets, H.; McCollam, A.; ...

    2016-12-02

    Here we present a de Haas–van Alphen study of the Fermi surface of the low-temperature antiferromagnet CeZn11 and its nonmagnetic analog LaZn11, measured by torque magnetometry up to fields of 33T and at temperatures down to 320 mK . Both systems possess similar de Haas–van Alphen frequencies, with three clear sets of features—ranging from 50 T to 4 kT —corresponding to three bands of a complex Fermi surface, with an expected fourth band also seen weakly in CeZn11 . The effective masses of the charge carriers are very light (<1 me) in LaZn11 but a factor of 2–4 larger inmore » CeZn11, indicative of stronger electronic correlations. We perform detailed density functional theory (DFT) calculations for CeZn11 and find that only DFT+ U calculations with U = 1.5 eV , which localize the 4 f states, provide a good match to the measured de Haas–van Alphen frequencies, once the presence of magnetic breakdown orbits is also considered. Finally, our study suggests that the Fermi surface of CeZn11 is very close to that of LaZn11 being dominated by Zn 3d , as the Ce 4 f states are localized and have little influence on its electronic structure, however, they are responsible for its magnetic order and contribute to enhance electronic correlations.« less

  18. Angular dependence of etch rates in the etching of poly-Si and fluorocarbon polymer using SF6, C4F8, and O2 plasmas

    NASA Astrophysics Data System (ADS)

    Min, Jae-Ho; Lee, Gyeo-Re; Lee, Jin-Kwan; Moon, Sang Heup; Kim, Chang-Koo

    2004-05-01

    The dependences of etch rates on the angle of ions incident on the substrate surface in four plasma/substrate systems that constitute the advanced Bosch process were investigated using a Faraday cage designed for the accurate control of the ion-incident angle. The four systems, established by combining discharge gases and substrates, were a SF6/poly-Si, a SF6/fluorocarbon polymer, an O2/fluorocarbon polymer, and a C4F8/Si. In the case of SF6/poly-Si, the normalized etch rates (NERs), defined as the etch rates normalized by the rate on the horizontal surface, were higher at all angles than values predicted from the cosine of the ion-incident angle. This characteristic curve shape was independent of changes in process variables including the source power and bias voltage. Contrary to the earlier case, the NERs for the O2/polymer decreased and eventually reached much lower values than the cosine values at angles between 30° and 70° when the source power was increased and the bias voltage was decreased. On the other hand, the NERs for the SF6/polymer showed a weak dependence on the process variables. In the case of C4F8/Si, which is used in the Bosch process for depositing a fluorocarbon layer on the substrate surface, the deposition rate varied with the ion incident angle, showing an S-shaped curve. These characteristic deposition rate curves, which were highly dependent on the process conditions, could be divided into four distinct regions: a Si sputtering region, an ion-suppressed polymer deposition region, an ion-enhanced polymer deposition region, and an ion-free polymer deposition region. Based on the earlier characteristic angular dependences of the etch (or deposition) rates in the individual systems, ideal process conditions for obtaining an anisotropic etch profile in the advanced Bosch process are proposed. .

  19. Genetic polymorphism of cytochrome P450 4F2, vitamin E level and histological response in adults and children with nonalcoholic fatty liver disease who participated in PIVENS and TONIC clinical trials.

    PubMed

    Athinarayanan, Shaminie; Wei, Rongrong; Zhang, Min; Bai, Shaochun; Traber, Maret G; Yates, Katherine; Cummings, Oscar W; Molleston, Jean; Liu, Wanqing; Chalasani, Naga

    2014-01-01

    Vitamin E improved liver histology in children and adults with NAFLD who participated in TONIC and PIVENS clinical trials, but with significant inter-individual variability in its efficacy. Cytochrome P450 4F2 (CYP4F2) is the major enzyme metabolizing Vit E, with two common genetic variants (V433M, rs2108622 and W12G, rs3093105) found to alter its activity. We investigated the relationship between CYP4F2 genotypes, α-tocopherol levels and histological improvement in these two trials. V433M and W12G variants were genotyped in TONIC (n = 155) and PIVENS (n = 213) DNA samples. The relationships between CYP4F2 genotypes, plasma α-tocopherol levels at baseline and weeks 48 (w48) and 96 (w96) and histological end points (overall improvement in liver histology and resolution of NASH) were investigated. As a result, the V433M genotype was significantly associated with baseline plasma α-tocopherol in the TONIC trial (p = 0.004), but not in PIVENS. Among those receiving Vit E treatment, CYP4F2 V433M genotype was associated with significantly decreased plasma α-tocopherol levels at w48 (p = 0.003 for PIVENS and p = 0.026 for TONIC) but not at w96. The w96 α-tocopherol level was significantly associated with resolution of NASH (p = 0.006) and overall histology improvement (p = 0.021)in the PIVENS, but not in the TONIC trial. There was no significant association between CYP4F2 genotypes and histological end points in either trial. Our study suggested the a moderate role of CYP4F2 polymorphisms in affecting the pharmacokinetics of Vit E as a therapeutic agent. In addition, there may be age-dependent relationship between CYP4F2 genetic variability and Vit E pharmacokinetics in NAFLD.

  20. XPS and UPS Studies of Thin Film PV Materials Modified by Reactions in Liquids

    SciTech Connect

    Perkins, C. L.; Hasoon, F. S.; Al-Thani, H. A.; Asher, S. E.

    2005-01-01

    Water-based processing steps are ubiquitous in the semiconductor industry, and the field of photovoltaics (PV) is no exception. During chemical bath deposition (CBD) of CdS, complex chemical reactions occurring at surfaces and in solution are poorly understood, yet have been shown to have powerful effects on the performance in terms of reliability and efficiency of finished PV devices. In the past, electron spectroscopic studies of these reactions have been hampered by the conflicting requirements of ultra-high vacuum and exposure of samples to liquid water. In this paper we present initial results from a new tool at NREL that allows one to conduct atmospheric pressure, liquid phase chemical processes on thin film PV materials and subsequent examination via core and valence level electron spectroscopies without exposing samples to air contamination.

  1. XPS depth profiling of derivatized amine and anhydride plasma polymers: Evidence of limitations of the derivatization approach

    NASA Astrophysics Data System (ADS)

    Manakhov, Anton; Michlíček, Miroslav; Felten, Alexandre; Pireaux, Jean-Jacques; Nečas, David; Zajíčková, Lenka

    2017-02-01

    The quantitative analysis of the chemistry at the surface of functional plasma polymers is highly important for the optimization of their deposition conditions and, therefore, for their subsequent applications. The chemical derivatization of amine and carboxyl-anhydride layers is a well-known technique already applied by many researchers, notwithstanding the known drawback of the derivatization procedures like side or uncomplete reactions that could lead to "unreliable" results. In this work, X-ray photoelectron spectroscopy (XPS) combined with depth profiling with argon clusters is applied for the first time to study derivatized amine and carboxyl-anhydride plasma polymer layers. It revealed an additional important parameter affecting the derivatization reliability, namely the permeation of the derivatizing molecule through the target analysed layer, i.e. the composite effect of the probe molecule size and the layer porosity. Amine-rich films prepared by RF low pressure plasma polymerization of cyclopropylamine were derivatized with trifluoromethyl benzaldehide (TFBA) and it was observed by that the XPS-determined NH2 concentration depth profile is rapidly decreasing over top ten nanometers of the layer. The anhydride-rich films prepared by atmospheric plasma co-polymerization of maleic anhydride and C2H2 have been reacted with, parafluoroaniline and trifluoroethyl amine. The decrease of the F signal in top surface layer of the anhydride films derivatized by the "large" parafluoroaniline was observed similarly as for the amine films but the derivatization with the smaller trifluoroethylamine (TFEA) led to a more homogenous depth profile. The data analysis suggests that the size of the derivatizing molecule is the main factor, showing that the very limited permeation of the TFBA molecule can lead to underestimated densities of primary amines if the XPS analysis is solely carried out at a low take-off angle. In contrast, TFEA is found to be an efficient

  2. [Quantitative surface analysis of Pt-Co, Cu-Au and Cu-Ag alloy films by XPS and AES].

    PubMed

    Li, Lian-Zhong; Zhuo, Shang-Jun; Shen, Ru-Xiang; Qian, Rong; Gao, Jie

    2013-11-01

    In order to improve the quantitative analysis accuracy of AES, We associated XPS with AES and studied the method to reduce the error of AES quantitative analysis, selected Pt-Co, Cu-Au and Cu-Ag binary alloy thin-films as the samples, used XPS to correct AES quantitative analysis results by changing the auger sensitivity factors to make their quantitative analysis results more similar. Then we verified the accuracy of the quantitative analysis of AES when using the revised sensitivity factors by other samples with different composition ratio, and the results showed that the corrected relative sensitivity factors can reduce the error in quantitative analysis of AES to less than 10%. Peak defining is difficult in the form of the integral spectrum of AES analysis since choosing the starting point and ending point when determining the characteristic auger peak intensity area with great uncertainty, and to make analysis easier, we also processed data in the form of the differential spectrum, made quantitative analysis on the basis of peak to peak height instead of peak area, corrected the relative sensitivity factors, and verified the accuracy of quantitative analysis by the other samples with different composition ratio. The result showed that the analytical error in quantitative analysis of AES reduced to less than 9%. It showed that the accuracy of AES quantitative analysis can be highly improved by the way of associating XPS with AES to correct the auger sensitivity factors since the matrix effects are taken into account. Good consistency was presented, proving the feasibility of this method.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  4. IR, NMR, XPS study of 1-( D-3-mercapto-2-methylpropionyl)- L-proline and its zinc complexes

    NASA Astrophysics Data System (ADS)

    Atzei, D.; De Filippo, D.; Rossi, A.; Lai, A.; Saba, G.; Bucci, R.

    1992-07-01

    Two Zn(II) complexes of captopril were prepared and characterized with different analytical methods: IR, NMR and XPS. Captopril is a molecule which has been proven to be very effective in reducing blood pressure. The ligand chelates via the OCO group to a zinc ion and via S and amidic oxygen atoms to another zinc ion when the ZnL complex is obtained. The sulphur atom and the amidic CO group are the only atoms involved in the coordination when the sodium—zinc complex, Na 2ZnL 2, is synthesized.

  5. Academic Rigor: The Core of the Core

    ERIC Educational Resources Information Center

    Brunner, Judy

    2013-01-01

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

  6. Method for determining the elemental composition and distribution in semiconductor core-shell quantum dots.

    PubMed

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

    2011-02-01

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

  7. Electron Dynamics at Dye-Semiconductor Interfaces probed with Picosecond Time-Resolved XPS

    NASA Astrophysics Data System (ADS)

    Neppl, Stefan; Shavorskiy, Andrey; Zegkinoglou, Ioannis; Fraund, Matthew; Salmeron, Miquel; Guo, Jinghua; Bluhm, Hendrik; Gessner, Oliver

    2014-05-01

    Picosecond time-resolved core-level spectroscopy using laser pulses to initiate and short X-ray pulses to probe photo-induced processes have the unique potential to provide electronic state- and atomic site-specific insight into fundamental electron dynamics in complex systems. Up to now, however, most of these experiments have concentrated on the electronic and structural dynamics in isolated or solvated molecules. Here we report preliminary results of a time-resolved X-ray photoelectron spectroscopy (TRXPS) study with the goal to follow the light-driven electron dynamics of N3 dye molecules adsorbed on a nano-structured ZnO semiconductor substrate - a technologically pertinent system for dye-sensitized solar cells - on the pico- to nanosecond time scale from the perspective of individual atomic sites at this complex interface. A distinct evolution of the molecular C1s photoemission line shape is observed as a function of time delay between a visible (532 nm) laser pump pulse (resonant with the N3 HOMO-LUMO gap) and the X-ray probe pulses. The observed changes in the C1s TRXPS spectra will be discussed in the context of possible charge recombination and relaxation processes leading to the neutralization of the transiently oxidized dye following ultrafast photo-induced electron injection.

  8. XPS study of interface formation of CVD SiO2 on InSb. [X-ray Photoemission Spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  9. Structural model of homogeneous As–S glasses derived from Raman spectroscopy and high-resolution XPS

    SciTech Connect

    Golovchak, R.; Shpotyuk, O.; Mccloy, J. S.; Riley, B. J.; Windisch, C. F.; Sundaram, S. K.; Kovalskiy, A.; Jain, H.

    2010-11-28

    The structure of homogeneous bulk As x S100- x (25 ≤ x ≤ 42) glasses, prepared by the conventional rocking–melting–quenching method, was investigated using high-resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. It is shown that the main building blocks of their glass networks are regular AsS3/2 pyramids and sulfur chains. In the S-rich domain, the existence of quasi-tetrahedral (QT) S = As(S1/2)3 units is deduced from XPS data, but with a concentration not exceeding ~3–5% of total atomic sites. Therefore, QT units do not appear as primary building blocks of the glass backbone in these materials, and an optimally-constrained network may not be an appropriate description for glasses when x < 40. Finally, it is shown that, in contrast to Se-based glasses, the ‘chain-crossing’ model is only partially applicable to sulfide glasses.

  10. An AFM, XPS and wettability study of the surface heterogeneity of PS/PMMA-r-PMAA demixed thin films.

    PubMed

    Zuyderhoff, Emilienne M; Dekeyser, Caroline M; Rouxhet, Paul G; Dupont-Gillain, Christine C

    2008-03-01

    A series of homopolymer/random copolymer blends was used to produce heterogeneous surfaces by demixing in thin films. The chosen homopolymer is polystyrene (PS) and the random copolymer is poly(methyl methacrylate)-r-poly(methacrylic acid) (PMMA-r-PMAA), whose acidic functions could be used as reactive sites in view of further surface functionalization. The proportion of each polymer at the interface was deduced from X-ray photoelectron spectroscopy (XPS) data using, on the one hand, the O/C ratio, and on the other hand, decomposition of the carbon peak of the blends in two components corresponding to the carbon peaks of PS and PMMA-r-PMAA. Combining the information from XPS with atomic force microscopy (AFM) images, water contact angle measurements and PS selective dissolution, it appears that the surfaces obtained from blends with a high PS content (90/10 to 70/30) display pits with a bottom made of PMMA-r-PMAA, randomly distributed in a PS matrix. On the other hand, the surfaces obtained from blends with a low PS content (30/70 to 10/90) display randomly distributed PS islands surrounded by a PMMA-r-PMAA matrix. The characteristics of the heterogeneous films are thought to be governed by the higher affinity of PMMA-r-PMAA for the solvent (dioxane), which leads to the elevation of the PS phase compared to the PMMA-r-PMAA phase, and to surface enrichment in PMMA-r-PMAA.

  11. Duplex Oxide Formation during Transient Oxidation of Cu-5%Ni(001) Investigated by In situ UHV-TEM and XPS

    SciTech Connect

    Yang, J.C.; Starr, D.; Kang, Y.; Luo, L.; Tong, X.; Zhou, G.

    2012-05-20

    The transient oxidation stage of a model metal alloy thin film was characterized with in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and analytic high-resolution TEM. We observed the formations of nanosized NiO and Cu{sub 2}O islands when Cu-5a5%Ni(100) was exposed to oxygen partial pressure, pO{sub 2} = 1 x 10{sup -4} Torr and various temperatures in situ. At 350 C epitaxial Cu{sub 2}O islands formed initially and then NiO islands appeared on the surface of the Cu{sub 2}O island, whereas at 750 C NiO appeared first. XPS and TEM was used to reveal a sequential formation of NiO and then Cu{sub 2}O islands at 550 C. The temperature-dependant oxide selection may be due to an increase of the diffusivity of Ni in Cu with increasing temperature.

  12. Multiplex pyrosequencing method to determine CYP2C9*3, VKORC1*2, and CYP4F2*3 polymorphisms simultaneously: its application to a Korean population and comparisons with other ethnic groups.

    PubMed

    Kim, Kyoung-Ah; Song, Wan-Geun; Lee, Hae-Mi; Joo, Hyun-Jin; Park, Ji-Young

    2014-11-01

    Warfarin is an anticoagulant that is difficult to administer because of the wide variation in dose requirements to achieve a therapeutic effect. CYP2C9, VKROC1, and CYP4F2 play important roles in warfarin metabolism, and their genetic polymorphisms are related to the variability in dose determination. In this study we describe a new multiplex pyrosequencing method to identify CYP2C9*3 (rs1057910), VKORC1*2 (rs9923231), and CYP4F2*3 (rs2108661) simultaneously. A multiplex pyrosequencing method to simultaneously detect CYP2C9*3, VKORC1*2, and CYP4F2*3 alleles was designed. We assessed the allele frequencies of the polymorphisms in 250 Korean subjects using the multiplex pyrosequencing method. The results showed 100 % concordance between single and multiplex pyrosequencing methods, and the polymorphisms identified by pyrosequencing were also validated with the direct sequencing method. The allele frequencies of these polymorphisms in this population were as follows: 0.040 for CYP2C9*3, 0.918 for VKORC1*2, and 0.416 for CYP4F2*3. Although the allele frequencies of the CYP2C9*3 and VKROC1*2 were comparable to those in Japanese and Chinese populations, their frequencies in this Korean population differed from those in other ethnic groups; the CYP4F2*3 frequency was the highest among other ethnic populations including Chinese and Japanese populations. The pyrosequencing methods developed were rapid and reliable for detecting CYP2C9*3, VKORC1*2, and CYP4F2*3. Large ethnic differences in the frequency of these genetic polymorphisms were noted among ethnic groups. CYP4F2*3 exhibited its highest allele frequency among other ethnic populations compared to that in a Korean population.

  13. Comparative study of smoke condensates from 1R4F cigarettes that burn tobacco versus ECLIPSE cigarettes that primarily heat tobacco in the SENCAR mouse dermal tumor promotion assay.

    PubMed

    Meckley, Daniel R; Hayes, Johnnie R; Van Kampen, K R; Ayres, Paul H; Mosberg, Arnold T; Swauger, James E

    2004-05-01

    Numerous chemical and toxicological studies indicate that smoke from ECLIPSE, a cigarette that primarily heats rather than burns tobacco, is simplified and reduced in specific chemicals believed to be associated with smoking-related diseases, and demonstrates reduced smoke toxicity and biological activity in vitro when compared to conventional tobacco burning cigarettes. These data led to the hypothesis that cigarette smoke condensate (CSC) from ECLIPSE should have lower tumorigenicity than 1R4F condensate in the SENCAR mouse dermal tumor promotion assay. Female SENCAR mice were initiated with a single topical application of 7,12-dimethylbenz[a]anthracene (DMBA) followed by promotion with ECLIPSE or 1R4F CSC. Dermal application of 10, 20, or 40 mg ECLIPSE or 1R4F CSC three times/week for 29 weeks did not alter body weights, survival or other indicators of subchronic toxicity. In DMBA-initiated mice, there were significant increases in both the number of microscopically confirmed tumor-bearing animals and total number of microscopically confirmed dermal tumors at all 1R4F CSC doses and the high-dose ECLIPSE CSC. However, the number of ECLIPSE tumor-bearing animals were reduced 83%, 93% and 67% at the low-, mid- and high-doses, respectively, compared to the 1R4F. Similarly, the total number of dermal tumors was reduced 91%, 94% and 87% at the low-, mid- and high-dose, respectively, compared to the 1R4F CSC. ECLIPSE CSC demonstrated dramatic reductions in dermal tumor promotion potential compared to 1R4F CSC.

  14. Characterizing fluorocarbon assisted atomic layer etching of Si using cyclic Ar/C4F8 and Ar/CHF3 plasma.

    PubMed

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

    2017-02-07

    With the increasing interest in establishing directional etching methods capable of atomic scale resolution for fabricating highly scaled electronic devices, the need for development and characterization of atomic layer etching processes, or generally etch processes with atomic layer precision, is growing. In this work, a flux-controlled cyclic plasma process is used for etching of SiO2 and Si at the Angstrom-level. This is based on steady-state Ar plasma, with periodic, precise injection of a fluorocarbon (FC) precursor (C4F8 and CHF3) and synchronized, plasma-based Ar(+) ion bombardment [D. Metzler et al., J. Vac. Sci. Technol., A 32, 020603 (2014) and D. Metzler et al., J. Vac. Sci. Technol., A 34, 01B101 (2016)]. For low energy Ar(+) ion bombardment conditions, physical sputter rates are minimized, whereas material can be etched when FC reactants are present at the surface. This cyclic approach offers a large parameter space for process optimization. Etch depth per cycle, removal rates, and self-limitation of removal, along with material dependence of these aspects, were examined as a function of FC surface coverage, ion energy, and etch step length using in situ real time ellipsometry. The deposited FC thickness per cycle is found to have a strong impact on etch depth per cycle of SiO2 and Si but is limited with regard to control over material etching selectivity. Ion energy over the 20-30 eV range strongly impacts material selectivity. The choice of precursor can have a significant impact on the surface chemistry and chemically enhanced etching. CHF3 has a lower FC deposition yield for both SiO2 and Si and also exhibits a strong substrate dependence of FC deposition yield, in contrast to C4F8. The thickness of deposited FC layers using CHF3 is found to be greater for Si than for SiO2. X-ray photoelectron spectroscopy was used to study surface chemistry. When thicker FC films of 11 Å are employed, strong changes of FC film chemistry during a cycle are seen

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

    With the increasing interest in establishing directional etching methods capable of atomic scale resolution for fabricating highly scaled electronic devices, the need for development and characterization of atomic layer etching processes, or generally etch processes with atomic layer precision, is growing. In this work, a flux-controlled cyclic plasma process is used for etching of SiO2 and Si at the Angstrom-level. This is based on steady-state Ar plasma, with periodic, precise injection of a fluorocarbon (FC) precursor (C4F8 and CHF3) and synchronized, plasma-based Ar+ ion bombardment [D. Metzler et al., J. Vac. Sci. Technol., A 32, 020603 (2014) and D. Metzler et al., J. Vac. Sci. Technol., A 34, 01B101 (2016)]. For low energy Ar+ ion bombardment conditions, physical sputter rates are minimized, whereas material can be etched when FC reactants are present at the surface. This cyclic approach offers a large parameter space for process optimization. Etch depth per cycle, removal rates, and self-limitation of removal, along with material dependence of these aspects, were examined as a function of FC surface coverage, ion energy, and etch step length using in situ real time ellipsometry. The deposited FC thickness per cycle is found to have a strong impact on etch depth per cycle of SiO2 and Si but is limited with regard to control over material etching selectivity. Ion energy over the 20-30 eV range strongly impacts material selectivity. The choice of precursor can have a significant impact on the surface chemistry and chemically enhanced etching. CHF3 has a lower FC deposition yield for both SiO2 and Si and also exhibits a strong substrate dependence of FC deposition yield, in contrast to C4F8. The thickness of deposited FC layers using CHF3 is found to be greater for Si than for SiO2. X-ray photoelectron spectroscopy was used to study surface chemistry. When thicker FC films of 11 Å are employed, strong changes of FC film chemistry during a cycle are seen

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

    SciTech Connect

    Lukens, Wayne W.; Speldrich, Manfred; Yang, Ping; Duignan, T. J.; Autschbach, J.; Kogerler, P.

    2016-05-31

    The electronic structures of 4f3/5f3 Cp"3M and Cp"3M·alkylisocyanide complexes, where Cp" is 1,3-bis-(trimethylsilyl)cyclopentadienyl, are explored with a focus on the splitting of the f-orbitals, which provides information about the strengths of the metal–ligand interactions. While the f-orbital splitting in many lanthanide complexes has been reported in detail, experimental determination of the f-orbital splitting in actinide complexes remains rare in systems other than halide and oxide compounds, since the experimental approach, crystal field analysis, is generally significantly more difficult for actinide complexes than for lanthanide complexes. In this study, a set of analogous neodymium(III) and uranium(III) tris-cyclopentadienyl complexes and their isocyanide adducts was characterized by electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility. The crystal field model was parameterized by combined fitting of EPR and susceptibility data, yielding an accurate description of f-orbital splitting. The isocyanide derivatives were also studied using density functional theory, resulting in f-orbital splitting that is consistent with crystal field fitting, and by multi-reference wavefunction calculations that support the electronic structure analysis derived from the crystal-field calculations. The results highlight that the 5f-orbitals, but not the 4f-orbitals, are significantly involved in bonding to the isocyanide ligands. The main interaction between isocyanide ligand and the metal center is a σ-bond, with additional 5f to π* donation for the uranium complexes. As a result, while interaction with the isocyanide π*-orbitals lowers the energies of the 5fxz2 and 5fyz2-orbitals, spin–orbit coupling greatly reduces the population of 5fxz2 and 5fyz2 in the ground state.

  17. Characterizing Fluorocarbon Assisted Atomic Layer Etching of Si Using Cyclic Ar/C4F8 and Ar/CHF3 Plasma

    DOE PAGES

    Metzler, Dominik; Li, Chen; Engelmann, Sebastian; ...

    2016-09-08

    With the increasing interest in establishing directional etching methods capable of atomic scale resolution for fabricating highly scaled electronic devices, the need for development and characterization of atomic layer etching (ALE) processes, or generally etch processes with atomic layer precision, is growing. In this work, a flux-controlled cyclic plasma process is used for etching of SiO2 and Si at the Angstrom-level. This is based on steady-state Ar plasma, with periodic, precise injection of a fluorocarbon (FC) precursor (C4F8 and CHF3), and synchronized, plasma-based Ar+ ion bombardment [D. Metzler et al., J Vac Sci Technol A 32, 020603 (2014), and D.more » Metzler et al., J Vac Sci Technol A 34, 01B101 (2016)]. For low energy Ar+ ion bombardment conditions, physical sputter rates are minimized, whereas material can be etched when FC reactants are present at the surface. This cyclic approach offers a large parameter space for process optimization. Etch depth per cycle, removal rates, and self-limitation of removal, along with material dependence of these aspects, were examined as a function of FC surface coverage, ion energy, and etch step length using in situ real time ellipsometry. The deposited FC thickness per cycle is found to have a strong impact on etch depth per cycle of SiO2 and Si, but is limited with regard to control over material etching selectivity. Ion energy over the 20 to 30 eV range strongly impacts material selectivity. The choice of precursor can have a significant impact on the surface chemistry and chemically enhanced etching. CHF3 has a lower FC deposition yield for both SiO2 and Si, and also exhibits a strong substrate dependence of FC deposition yield, in contrast to C4F8. The thickness of deposited FC layers using CHF3 is found to be greater for Si than for SiO2. X-ray photoelectron spectroscopy was used to study surface chemistry. When thicker FC films of 11 Å are employed, strong changes of FC film chemistry during a cycle are

  18. X-ray photoelectron spectroscopy (XPS) investigation of the surface film on magnesium powders.

    PubMed

    Burke, Paul J; Bayindir, Zeynel; Kipouros, Georges J

    2012-05-01

    Magnesium (Mg) and its alloys are attractive for use in automotive and aerospace applications because of their low density and good mechanical properties. However, difficulty in forming magnesium and the limited number of available commercial alloys limit their use. Powder metallurgy may be a suitable solution for forming near-net-shape parts. However, sintering pure magnesium presents difficulties due to surface film that forms on the magnesium powder particles. The present work investigates the composition of the surface film that forms on the surface of pure magnesium powders exposed to atmospheric conditions and on pure magnesium powders after compaction under uniaxial pressing at a pressure of 500 MPa and sintering under argon at 600 °C for 40 minutes. Initially, focused ion beam microscopy was utilized to determine the thickness of the surface layer of the magnesium powder and found it to be ~10 nm. The X-ray photoelectron analysis of the green magnesium sample prior to sintering confirmed the presence of MgO, MgCO(3)·3H(2)O, and Mg(OH)(2) in the surface layer of the powder with a core of pure magnesium. The outer portion of the surface layer was found to contain MgCO(3)·3H(2)O and Mg(OH)(2), while the inner portion of the layer is primarily MgO. After sintering, the MgCO(3)·3H(2)O was found to be almost completely absent, and the amount of Mg(OH)(2) was also decreased significantly. This is postulated to occur by decomposition of the compounds to MgO and gases during the high temperature of sintering. An increase in the MgO content after sintering supports this theory.

  19. Organized thiol functional groups in mesoporous core shell colloids

    SciTech Connect

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

    2012-03-15

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

  20. Coring Sample Acquisition Tool

    NASA Technical Reports Server (NTRS)

    Haddad, Nicolas E.; Murray, Saben D.; Walkemeyer, Phillip E.; Badescu, Mircea; Sherrit, Stewart; Bao, Xiaoqi; Kriechbaum, Kristopher L.; Richardson, Megan; Klein, Kerry J.

    2012-01-01

    A sample acquisition tool (SAT) has been developed that can be used autonomously to sample drill and capture rock cores. The tool is designed to accommodate core transfer using a sample tube to the IMSAH (integrated Mars sample acquisition and handling) SHEC (sample handling, encapsulation, and containerization) without ever touching the pristine core sample in the transfer process.

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

    SciTech Connect

    Trowbridge, L.D.

    1999-03-01

    As part of a program intended to replace the present evaporative coolant at the gaseous diffusion plants (GDPs) with a non-ozone-depleting alternate, a series of investigations of the suitability of candidate substitutes in under way. One issue concerning a primary candidate, c-C4F8, is the possibility that it might produce the highly toxic perfluoroisobutylene (PFIB) in high temperature environments. This study was commissioned to determine the likelihood and severity of decomposition under two specific high temperature thermal environments, namely the use of a flame test for the presence of coolant vapors and welding in the presence of coolant vapors. The purpose of the study was to develop and evaluate available data to provide information that will allow the technical and industrial hygiene staff at the GDPs to perform appropriate safety evaluations and to determine the need for field testing or experimental work. The scope of this study included a literature search and an evaluation of the information developed therefrom. Part of that evaluation consists of chemical kinetics modeling of coolant decomposition in the two operational environments. The general conclusions are that PFIB formation is unlikely in either situation but that it cannot be ruled out completely under extreme conditions. The presence of oxygen, moisture, and combustion products will tend to lead to formation of oxidation products (COF2, CO, CO2, and HF) rather than PFIB.

  2. Stark-assisted population control of coherent CS(2) 4f and 5p Rydberg wave packets studied by femtosecond time-resolved photoelectron spectroscopy.

    PubMed

    Knappenberger, Kenneth L; Lerch, Eliza-Beth W; Wen, Patrick; Leone, Stephen R

    2007-09-28

    A two-color (3+1(')) pump-probe scheme is employed to investigate Rydberg wave packet dynamics in carbon disulfide (CS(2) (*)). The state superpositions are created within the 4f and 5p Rydberg manifolds by three photons of the 400 nm pump pulse, and their temporal evolution is monitored with femtosecond time-resolved photoelectron spectroscopy using an 800 nm ionizing probe pulse. The coherent behavior of the non-stationary superpositions are observed through wavepacket revivals upon ionization to either the upper (12) or lower (32) spin-orbit components of CS(2) (+). The results show clearly that the composition of the wavepacket can be efficiently controlled by the power density of the excitation pulse over a range from 500 GWcm(2) to 10 TWcm(2). The results are consistent with the anticipated ac-Stark shift for 400 nm light and demonstrate an effective method for population control in molecular systems. Moreover, it is shown that Rydberg wavepackets can be formed in CS(2) with excitation power densities up to 10 TWcm(2) without significant fragmentation. The exponential 1e population decay (T(1)) of specific excited Rydberg states are recovered by analysis of the coherent part of the signal. The dissociation lifetimes of these states are typically 1.5 ps. However, a region exhibiting a more rapid decay ( approximately 800 fs) is observed for states residing in the energy range of 74 450-74 550 cm(-1), suggestive of an enhanced surface crossing in this region.

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

    PubMed Central

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

    2012-01-01

    Here, we have characterized a step in translation initiation of viral and cellular mRNAs that contain RNA secondary structures immediately at the vicinity of their m7GTP cap. This is mediated by the DEAD-box helicase DDX3 which can directly bind to the 5′ of the target mRNA where it clamps the entry of eIF4F through an eIF4G and Poly A-binding protein cytoplasmic 1 (PABP) double interaction. This could induce limited local strand separation of the secondary structure to allow 43S pre-initiation complex attachment to the 5′ free extremity of the mRNA. We further demonstrate that the requirement for DDX3 is highly specific to some selected transcripts, cannot be replaced or substituted by eIF4A and is only needed in the very early steps of ribosome binding and prior to 43S ribosomal scanning. Altogether, these data define an unprecedented role for a DEAD-box RNA helicase in translation initiation. PMID:22872150

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    PubMed

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

    2000-08-21

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

  6. Laser-induced fluorescence studies of excited Sr reactions: II. Sr(3P1)+CH3F, C2H5F, C2H4F2

    NASA Astrophysics Data System (ADS)

    Teule, J. M.; Janssen, M. H. M.; Bulthuis, J.; Stolte, S.

    1999-06-01

    The vibrational and rotational energy distributions of ground state SrF(X 2Σ) formed in the reactions of electronically excited Sr(3P1) with methylfluoride, ethylfluoride, and 1,1-difluoroethane have been studied by laser-induced fluorescence. Although the reactions of ground state Sr with these reactants are exothermic, no SrF products are observed for those reactions in this study. The fraction of available energy disposed into the sum of rotational and vibrational energy of the SrF(X 2Σ) product is approximately the same for all three reactions, i.e., 40%. The reaction of Sr(3P1) with CH3F results in very low vibrational excitation in the SrF reaction product. The product vibration increases in going to C2H5F and C2H4F2. It is concluded that the alkyl group influences the energy disposal mechanism in these reactions, and some suggestions are given for a partial explanation of the observations.

  7. Novel Concentrated Li[(FSO2)(n-C4F9SO2)N]-Based Ether Electrolyte for Superior Stability of Metallic Lithium Anode.

    PubMed

    Fang, Zheng; Ma, Qiang; Liu, Pin; Ma, Jie; Hu, Yong-Sheng; Zhou, Zhibin; Li, Hong; Huang, Xuejie; Chen, Liquan

    2017-02-08

    Lithium (fluorosulfonyl)(n-nonafluorobutanesulfonyl)imide [Li[(FSO2)(n-C4F9SO2)N] (LiFNFSI)] is investigated as a conducting salt, which can form a relatively stable solid-electrolyte-interphase film in concentrated ether electrolyte to achieve favorable protection for lithium metal anodes. Li|Cu and Li|Li cells with concentrated LiFNFSI-based electrolyte have been demonstrated to display high average Coulombic efficiency (≈97%) and excellent cycling stability (over 1,000 h) of metallic lithium anodes, compared to concentrated lithium bis(trifluoromethanesulfonyl)imide [Li[N(SO2CF3)2] (LiTFSI)]-based electrolyte. The morphologies and compositions of the lithium-metal anode surface are also comparatively analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Moreover, superior electrochemical performance in the concentrated LiFNFSI-based electrolyte for Li|LiFePO4 cells is also presented herein. These results indicate that concentrated LiFNFSI-based electrolyte is a promising candidate for metallic lithium rechargeable batteries.

  8. Photocatalytic performance of freestanding tetragonal zirconia nanotubes formed in H2O2/NH4F/ethylene glycol electrolyte by anodisation of zirconium

    NASA Astrophysics Data System (ADS)

    Rozana, Monna; Izza Soaid, Nurul; Kian, Tan Wai; Kawamura, Go; Matsuda, Atsunori; Lockman, Zainovia

    2017-04-01

    ZrO2 nanotubes (ZrNTs) were produced by anodisation of zirconium foil in H2O2/NH4F/ethylene glycol electrolyte. The as-anodised foils were then soaked in the anodising electrolyte for 12 h. Soaking weakens the adherence of the anodic layer from the substrate resulting in freestanding ZrNTs (FS-ZrNTs). Moreover, the presence of H2O2 in the electrolyte also aids in weakening the adhesion of the film from the foil, as foil anodised in electrolyte without H2O2 has good film adherence. The as-anodised FS-ZrNTs film was amorphous and crystallised to predominantly tetragonal phase upon annealing at >300 °C. Annealing must, however, be done at <500 °C to avoid monoclinic ZrO2 formation and nanotubes disintegration. FS-ZrNTs annealed at 450 °C exhibited the highest photocatalytic ability to degrade methyl orange (MO), whereby 82% MO degradation was observed after 5 h, whereas FS-ZrNTs with a mixture of monoclinic and tetragonal degraded 70% of MO after 5 h.

  9. A novel orange emitting Sm3+ ions doped NaCaAlPO4F3 phosphor: Optical and luminescence properties

    NASA Astrophysics Data System (ADS)

    Nagaraja, R.; Pushpa Manjari, V.; Sailaja, B.; Ravikumar, R. V. S. S. N.

    2017-02-01

    A novel orange light emitting Sm3+ ions doped NaCaAlPO4F3 phosphor was synthesized via solid state reaction. The prepared sample was characterized by powder X-ray diffraction (PXRD), Optical absorption, Photoluminescence (PL) and Fourier Transform Infrared Spectroscopy (FT-IR) techniques. From powder XRD data, the average crystallite size and structural parameters are estimated. Absorption spectra consist of ten absorption peaks corresponding to the transitions from the 6H5/2 ground state to various excited energy levels. Transition probabilities, branching ratios and radiative lifetime were evaluated by using Judd-Ofelt analysis. Photoluminescence spectrum show three prominent emission bands centered at 562, 597 and 643 nm corresponding to the 4G5/2 → 6HJ (J = 5/2, 7/2 and 9/2) transitions respectively. From the emission transitions, stimulated emission cross-section (σe) and gain bandwidth (GBW) were predicted. The decay profiles of the prepared phosphor reveals the single exponential nature and the experimental lifetime is calculated. The colorimetric parameters CIE coordinates, Correlated color temperature of the prepared phosphor are also evaluated. FT-IR spectrum demonstrates the characteristic vibration bands of the prepared phosphor material.

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

    PubMed

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

    2015-03-15

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

  11. Atmospheric chemistry of C4F9OC2H5 (HFE-7200), C4F9OCH3 (HFE-7100), C3F7OCH3 (HFE-7000) and C3F7CH2OH: temperature dependence of the kinetics of their reactions with OH radicals, atmospheric lifetimes and global warming potentials.

    PubMed

    Bravo, Iván; Díaz-de-Mera, Yolanda; Aranda, Alfonso; Smith, Kevin; Shine, Keith P; Marston, George

    2010-05-21

    The atmospheric chemistry of several gases used in industrial applications, C(4)F(9)OC(2)H(5) (HFE-7200), C(4)F(9)OCH(3) (HFE-7100), C(3)F(7)OCH(3) (HFE-7000) and C(3)F(7)CH(2)OH, has been studied. The discharge flow technique coupled with mass-spectrometric detection has been used to study the kinetics of their reactions with OH radicals as a function of temperature. The infrared spectra of the compounds have also been measured. The following Arrhenius expressions for the reactions were determined (in units of cm(3) molecule(-1) s(-1)): k(OH + HFE-7200) = (6.9(-1.7)(+2.3)) x 10(-11) exp(-(2030 +/- 190)/T); k(OH + HFE-7100) = (2.8(-1.5)(+3.2)) x 10(-11) exp(-(2200 +/- 490)/T); k(OH + HFE-7000) = (2.0(-0.7)(+1.2)) x 10(-11) exp(-(2130 +/- 290)/T); and k(OH + C(3)F(7)CH(2)OH) = (1.4(-0.2)(+0.3)) x 10(-11) exp(-(1460 +/- 120)/T). From the infrared spectra, radiative forcing efficiencies were determined and compared with earlier estimates in the literature. These were combined with the kinetic data to estimate 100-year time horizon global warming potentials relative to CO(2) of 69, 337, 499 and 36 for HFE-7200, HFE-7100, HFE-7000 and CF(3)CF(2)CF(2)CH(2)OH, respectively.

  12. Novel method for the preparation of core-shell nanoparticles with movable Ag core and polystyrene loop shell

    SciTech Connect

    Liu Weijun; Zhang Zhicheng . E-mail: lwj3600@ustc.edu; He Weidong; Zheng Cheng; Ge Xuewu; Li, Jian; Liu Huarong; Jiang Hao

    2006-04-15

    Core/shell nanoparticles with movable silver (Ag) core and polystyrene (PSt) shell (Ag at PSt nanoparticle) were successfully synthesized at room temperature and under ambient pressure via two steps: {gamma}-irradiation and interfacial-initiated polymerization. Firstly, mono-dispersed Ag nanoparticles with diameters 20 nm were synthesized in inversed microemulsion by reducing silver nitrate under {gamma}-irradiation. Then, Ag nanoparticles were coated with PSt via interfacial-initiated polymerization with cumene hydroperoxide/ferrous sulfate/disodium ethylenediaminetetraacetate/sodium formaldehyde sulfoxylate (CHPO-Fe {sup 2+}-EDTA-SFS) as the redox initiation pair. The resulted Ag at PSt nanoparticles were identified by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS)

  13. Novel method for the preparation of core shell nanoparticles with movable Ag core and polystyrene loop shell

    NASA Astrophysics Data System (ADS)

    Liu, Wei-Jun; Zhang, Zhi-Cheng; He, Wei-Dong; Zheng, Cheng; Ge, Xue-Wu; Li, Jian; Liu, Hua-Rong; Jiang, Hao

    2006-04-01

    Core/shell nanoparticles with movable silver (Ag) core and polystyrene (PSt) shell (Ag@PSt nanoparticle) were successfully synthesized at room temperature and under ambient pressure via two steps: γ-irradiation and interfacial-initiated polymerization. Firstly, mono-dispersed Ag nanoparticles with diameters 20 nm were synthesized in inversed microemulsion by reducing silver nitrate under γ-irradiation. Then, Ag nanoparticles were coated with PSt via interfacial-initiated polymerization with cumene hydroperoxide/ferrous sulfate/disodium ethylenediaminetetraacetate/sodium formaldehyde sulfoxylate (CHPO-Fe 2+-EDTA-SFS) as the redox initiation pair. The resulted Ag@PSt nanoparticles were identified by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

  14. Banded transformer cores

    NASA Technical Reports Server (NTRS)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

  15. HYDRATE CORE DRILLING TESTS

    SciTech Connect

    John H. Cohen; Thomas E. Williams; Ali G. Kadaster; Bill V. Liddell

    2002-11-01

    The ''Methane Hydrate Production from Alaskan Permafrost'' project is a three-year endeavor being conducted by Maurer Technology Inc. (MTI), Noble, and Anadarko Petroleum, in partnership with the U.S. DOE National Energy Technology Laboratory (NETL). The project's goal is to build on previous and ongoing R&D in the area of onshore hydrate deposition. The project team plans to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope includes drilling and coring one well on Anadarko leases in FY 2003 during the winter drilling season. A specially built on-site core analysis laboratory will be used to determine some of the physical characteristics of the hydrates and surrounding rock. Prior to going to the field, the project team designed and conducted a controlled series of coring tests for simulating coring of hydrate formations. A variety of equipment and procedures were tested and modified to develop a practical solution for this special application. This Topical Report summarizes these coring tests. A special facility was designed and installed at MTI's Drilling Research Center (DRC) in Houston and used to conduct coring tests. Equipment and procedures were tested by cutting cores from frozen mixtures of sand and water supported by casing and designed to simulate hydrate formations. Tests were conducted with chilled drilling fluids. Tests showed that frozen core can be washed out and reduced in size by the action of the drilling fluid. Washing of the core by the drilling fluid caused a reduction in core diameter, making core recovery very difficult (if not impossible). One successful solution was to drill the last 6 inches of core dry (without fluid circulation). These tests demonstrated that it will be difficult to capture core when drilling in permafrost or hydrates without implementing certain safeguards. Among the coring tests was a simulated hydrate formation comprised of coarse, large

  16. Development of core-shell coaxially electrospun composite PCL/chitosan scaffolds.

    PubMed

    Surucu, Seda; Turkoglu Sasmazel, Hilal

    2016-11-01

    This study was related to combining of synthetic Poly (ε-caprolactone) (PCL) and natural chitosan polymers to develop three dimensional (3D) PCL/chitosan core-shell scaffolds for tissue engineering applications. The scaffolds were fabricated with coaxial electrospinning technique and the characterizations of the samples were done by thickness and contact angle (CA) measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS) analyses, mechanical and PBS absorption and shrinkage tests. The average inter-fiber diameter values were calculated for PCL (0.717±0.001μm), chitosan (0.660±0.007μm) and PCL/chitosan core-shell scaffolds (0.412±0.003μm), also the average inter-fiber pore size values exhibited decreases of 66.91% and 61.90% for the PCL and chitosan scaffolds respectively, compared to PCL/chitosan core-shell ones. XPS analysis of the PCL/chitosan core-shell structures exhibited the characteristic peaks of PCL and chitosan polymers. The cell culture studies (MTT assay, Confocal Laser Scanning Microscope (CLSM) and SEM analyses) carried out with L929 ATCC CCL-1 mouse fibroblast cell line proved that the biocompatibility performance of the scaffolds. The obtained results showed that the created micro/nano fibrous structure of the PCL/chitosan core-shell scaffolds in this study increased the cell viability and proliferation on/within scaffolds.

  17. Spectroscopic characterization of iron ores formed in different geological environments using FTIR, XPS, Mössbauer spectroscopy and thermoanalyses

    NASA Astrophysics Data System (ADS)

    Salama, Walid; El Aref, Mourtada; Gaupp, Reinhard

    2015-02-01

    Application of thermoanalyses, FTIR, XPS and Mössbauer spectroscopic methods can differentiate between iron ores formed in different geological environments. Two types of iron ore are formed in shallow marine environments in the Bahariya Depression, Egypt, yellowish brown ooidal ironstones (type 1) and black mud and fossiliferous ironstones (type 2). Both types were subjected to subaerial weathering, producing a dark brown lateritic (pedogenic) iron ore (type 3). Microscopic investigation indicates goethite is the main mineral in types 1 and 3, while hematite is the main mineral in type 2 and also occurs in type 3. Thermoanalyses indicated the dehydroxylation endothermic peak of goethite of type 1 occurs between 329 and 345 °C, while in type 3 occurs between 284 and 330 °C. This variation can be attributed to the nanocrystalline nature of the pedogenic goethite. The presence of an exothermic peak at 754 °C in type 3 is probably attributed to goethite-hematite phase transformation. FTIR spectroscopy indicated that goethite of type 1 is characterized by the presence of the δ-OH band between 799 and 802 cm-1, the γ-OH between 898 and 904 cm-1 and the bulk hydroxyl stretch between 3124 and 3133 cm-1. Goethite of type 3 is characterized by the absence of the bulk hydroxyl stretch band and the δ-OH and γ-OH are shifted to higher Wavenumbers that can attributed to a relative Al-for Fe-substitution. Hematite is identified by two IR bands; the first is between 464 and 475 cm-1 and at the second is between 540 and 557 cm-1. Quartz is identified in all iron ore types, nitrates are identified in types 1 and 2, but absent in type 3 and Kaolinite is identified in type 2. The Mössbauer spectrum of type 1 is fitted with one magnetic sextet corresponding to goethite with an isomer shift (IS) = 0.374 mm s-1, a quadruple splitting (QS) = -0.27 mm s-1 and a hyperfine magnetic field (BHF) = ∼37. The Mössbauer spectrum of type 2 is fitted with one magnetic sextet

  18. XPS study of the chemical stability of DyBa2Cu3O6+δ superconductor

    NASA Astrophysics Data System (ADS)

    Fetisov, A. V.; Kozhina, G. А.; Estemirova, S. Kh.; Fetisov, V. B.; Gulyaeva, R. I.

    2015-01-01

    The chemical stability of the powder DyBa2Cu3O6+δ has been studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermal analysis at ambient conditions. The powder was subjected to mechanical processing in a ball mill-activator to accelerate chemical degradation. The kinetic regularities of hydrolytic decomposition of DyBa2Cu3O6+δ under the influence of air moisture have been determined. The resistive properties of DyBa2Cu3O6+δ to water have been found to be better, but not much different from analogous properties of YBa2Cu3O6+δ which is unstable in a wet environment. Chemical degradation of the material is triggered by crucial concentrating of water particles near the free surface of the solid reactant (due to their low diffusibility in the bulk) leading to rapid chemical decomposition of the respective regions.

  19. Intensity analysis of XPS spectra to determine oxide uniformity - Application to SiO2/Si interfaces

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    A simple method of determining oxide uniformity is derived which requires no knowlege of film thickness, escape depth, or film composition. The method involves only the measurement of oxide and substrate intensities and is illustrated by analysis of XPS spectral data for thin SiO2 films grown both thermally and by low-temperature chemical vapor deposition on monocrystalline Si. A region 20-30 A thick is found near the SiO2/Si interface on thermally oxidized samples which has an inelastic mean free path 35% less than that found in the bulk oxide. This is interpreted as being due to lattice mismatch resulting in a strained region which is structurally, but not stoichiometrically, distinct from the bulk oxide.

  20. Growth of ultra-thin FeO(100) films on Ag(100): A combined XPS, LEED and CEMS study

    NASA Astrophysics Data System (ADS)

    Abreu, G. J. P.; Paniago, R.; Pfannes, H.-D.

    2014-01-01

    The production and characterization of ultra-thin iron oxide films grown on an atomically clean Ag(100) surface by molecular beam epitaxy (MBE) is presented. The goal of this work was to prepare ultra-thin FeO(100) with excellent crystallographic quality. The films were prepared with high purity 57Fe and O2 and afterwards analyzed in situ by means of Low Energy Electron Diffraction (LEED), X-Ray Photoelectron Spectroscopy (XPS) and Conversion Electron Mössbauer Spectroscopy (CEMS). During preparation the evaporation rate, the O2 partial pressure, film thickness and annealing procedures were varied. The analysis of the various samples showed that in general a mixture of FeO and Fe3O4 phases is obtained. We determined the best conditions to produce the desired oxide (FeO). Besides the paramagnetic phase, the antiferromagnetic phase of the FeO films was characterized by low temperature Mössbauer spectra.

  1. Surface chemical composition of human maxillary first premolar as assessed by X-ray photoelectron spectroscopy (XPS)

    NASA Astrophysics Data System (ADS)

    Lou, Leo; Nelson, Alan E.; Heo, Giseon; Major, Paul W.

    2008-08-01

    The surface chemical composition of dental enamel has been postulated as a contributing factor in the variation of bond strength of brackets bonded to teeth, and hence, the probability of bracket failure during orthodontic treatment. This study systematically investigated the chemical composition of 98 bonding surfaces of human maxillary premolars using X-ray photoelectron spectroscopy (XPS) to ascertain compositional differences between right and left first premolars. The major elements detected in all samples were calcium, phosphorus, oxygen, nitrogen and carbon. Surface compositions were highly variable between samples and several elements were found to be highly correlated. No statistical significant difference in the chemical composition of the maxillary right and left first premolars was found ( p > 0.05). Knowledge of the chemical composition of enamel surfaces will facilitate future studies that relate this information to the variations in dental enamel bond strength.

  2. Multiple Coordination of CO on Molybdenum Nanoparticles: Evidence for Intermediate Mox(CO)y Species by XPS and UPS.

    PubMed

    Jiang, Zhiquan; Huang, Weixin; Zhang, Zhen; Zhao, Hong; Tan, Dali; Bao, Xinhe

    2006-12-28

    CO chemisorption on the metallic molybdenum nanoparticles supported on the thin alumina film was investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). A binary compound of molybdenum and CO is found to be formed on the surface upon CO dose, accompanied with a positive binding energy shift of the Mo 3d doublet and a localized Mo 4d valence band. A loose packing of the metallic molybdenum favors the formation of this intermediate Mox(CO)y species. The formation of the Mox(CO)y species implies that the property of the metallic molybdenum nanoparticles on the thin alumina film is much different from that of the bulk molybdenum, indicating a significant nanometer size effect.

  3. 23. CORE WORKER OPERATING A COREBLOWER THAT PNEUMATICALLY FILLED CORE ...

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

    23. CORE WORKER OPERATING A CORE-BLOWER THAT PNEUMATICALLY FILLED CORE BOXES WITH RESIGN IMPREGNATED SAND AND CREATED A CORE THAT THEN REQUIRED BAKING, CA. 1950. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  4. Highly efficient removal of heavy metals by polymer-supported nanosized hydrated Fe(III) oxides: behavior and XPS study.

    PubMed

    Pan, Bingjun; Qiu, Hui; Pan, Bingcai; Nie, Guangze; Xiao, Lili; Lv, Lu; Zhang, Weiming; Zhang, Quanxing; Zheng, Shourong

    2010-02-01

    The present study developed a polymer-based hybrid sorbent (HFO-001) for highly efficient removal of heavy metals [e.g., Pb(II), Cd(II), and Cu(II)] by irreversibly impregnating hydrated Fe(III) oxide (HFO) nanoparticles within a cation-exchange resin D-001 (R-SO(3)Na), and revealed the underlying mechanism based on X-ray photoelectron spectroscopy (XPS) study. HFO-001 combines the excellent handling, flow characteristics, and attrition resistance of conventional cation-exchange resins with the specific affinity of HFOs toward heavy metal cations. As compared to D-001, sorption selectivity of HFO-001 toward Pb(II), Cu(II), and Cd(II) was greatly improved from the Ca(II) competition at greater concentration. Column sorption results indicated that the working capacity of HFO-001 was about 4-6 times more than D-001 with respect to removal of three heavy metals from simulated electroplating water (pH approximately 4.0). Also, HFO-001 is particularly effective in removing trace Pb(II) and Cd(II) from simulated natural waters to meet the drinking water standard, with treatment volume orders of magnitude higher than D-001. The superior performance of HFO-001 was attributed to the Donnan membrane effect exerted by the host D-001 as well as to the impregnated HFO nanoparticles of specific interaction toward heavy metal cations, as further confirmed by XPS study on lead sorption. More attractively, the exhausted HFO-001 beads can be effectively regenerated by HCl-NaCl solution (pH 3) for repeated use without any significant capacity loss.

  5. Tracking the conversion of nitrogen during pyrolysis of antibiotic mycelial fermentation residues using XPS and TG-FTIR-MS technology.

    PubMed

    Zhu, Xiangdong; Yang, Shijun; Wang, Liang; Liu, Yuchen; Qian, Feng; Yao, Wenqing; Zhang, Shicheng; Chen, Jianmin

    2016-04-01

    Antibiotic mycelial fermentation residues (AMFRs), which are emerging solid pollutants, have been recognized as hazardous waste in China since 2008. Nitrogen (N), which is an environmental sensitivity element, is largely retained in AMFR samples derived from fermentation substrates. Pyrolysis is a promising technology for the treatment of solid waste. However, the outcomes of N element during the pyrolysis of AMFRs are still unknown. In this study, the conversion of N element during the pyrolysis of AMFRs was tracked using XPS (X-ray photoelectron spectroscopy) and online TG-FTIR-MS (Thermogravimetry-Fourier transform infrared-Mass spectrometry) technology. In the AMFR sample, organic amine-N, pyrrolic-N, protein-N, pyridinic-N, was the main N-containing species. XPS results indicated that pyrrolic-N and pyridinic-N were retained in the AMFR-derived pyrolysis char. More stable species, such as N-oxide and quaternary-N, were also produced in the char. TG-FTIR-MS results indicated that NH3 and HCN were the main gaseous species, and their contents were closely related to the contents of amine-N and protein-N, and pyrrolic-N and pyridinic-N of AMFRs, respectively. Increases in heating rate enhanced the amounts of NH3 and HCN, but had less of an effect on the degradation degree of AMFRs. N-containing organic compounds, including amine-N, nitrile-N and heterocyclic-N, were discerned from the AMFR pyrolysis process. Their release range was extended with increasing of heating rate and carbon content of AMFR sample. This work will help to take appropriate measure to reduce secondary pollution from the treatment of AMFRs.

  6. Electronic structure of rare-earth nitrides using the LSDA+U approach: Importance of allowing 4f orbitals to break the cubic crystal symmetry

    NASA Astrophysics Data System (ADS)

    Larson, P.; Lambrecht, Walter R. L.; Chantis, Athanasios; van Schilfgaarde, Mark

    2007-01-01

    Electronic structure calculations were performed for the rare-earth (RE) nitrides in the rocksalt structure using density functional theory calculations within the LSDA+U approach (local spin density approximation with Hubbard- U corrections). The LSDA+U method is implemented in the full-potential linearized muffin-tin orbital method and applied to the 4f as well as 5d states. Parameters U and J were determined from atomic calculations complemented with experimental photoemission and inverse photoemission data and optical absorption data for Gd pnictides. The solution for the density matrix of f electrons is not unique and thus several configurations need to be investigated to determine the lowest energy state. A trivalent solution is found to have the lowest energy in all cases except CeN , which was found to be tetravalent. Hund’s second rule requires maximizing the orbital momentum component Lz , which breaks the cubic symmetry and lowers the total energy. We find Hund’s second rule to be obeyed in all cases except EuN and YbN , where a cubic symmetry solution has lower energy. In these cases, the divalent solution is also in competition with the trivalent solution. The symmetry breaking in most cases lowers the total energy and in some cases, those with two electrons or holes away from a closed or half-filled shell, is essential to remove f states from the Fermi level. The spin magnetic moments are nearly integer, defined by the number of filled 4f states. The orbital magnetic moment is of comparable magnitude to the spin moment. Hund’s third rule, according to which the orbital and spin moment are opposite to each other in the first half of the series but parallel to each other in the second half, is also found to be obeyed. Interestingly, this leads to zero net magnetic moment for SmN .Apart from the few cases where f states remain close to the Fermi level, the band structure is borderline semiconductor to semimetallic in most cases, a RE 5d conduction

  7. Core-Cutoff Tool

    NASA Technical Reports Server (NTRS)

    Gheen, Darrell

    2007-01-01

    A tool makes a cut perpendicular to the cylindrical axis of a core hole at a predetermined depth to free the core at that depth. The tool does not damage the surrounding material from which the core was cut, and it operates within the core-hole kerf. Coring usually begins with use of a hole saw or a hollow cylindrical abrasive cutting tool to make an annular hole that leaves the core (sometimes called the plug ) in place. In this approach to coring as practiced heretofore, the core is removed forcibly in a manner chosen to shear the core, preferably at or near the greatest depth of the core hole. Unfortunately, such forcible removal often damages both the core and the surrounding material (see Figure 1). In an alternative prior approach, especially applicable to toxic or fragile material, a core is formed and freed by means of milling operations that generate much material waste. In contrast, the present tool eliminates the damage associated with the hole-saw approach and reduces the extent of milling operations (and, hence, reduces the waste) associated with the milling approach. The present tool (see Figure 2) includes an inner sleeve and an outer sleeve and resembles the hollow cylindrical tool used to cut the core hole. The sleeves are thin enough that this tool fits within the kerf of the core hole. The inner sleeve is attached to a shaft that, in turn, can be attached to a drill motor or handle for turning the tool. This tool also includes a cutting wire attached to the distal ends of both sleeves. The cutting wire is long enough that with sufficient relative rotation of the inner and outer sleeves, the wire can cut all the way to the center of the core. The tool is inserted in the kerf until its distal end is seated at the full depth. The inner sleeve is then turned. During turning, frictional drag on the outer core pulls the cutting wire into contact with the core. The cutting force of the wire against the core increases with the tension in the wire and

  8. 3d-4f Metal-Organic Framework with Dual Luminescent Centers That Efficiently Discriminates the Isomer and Homologues of Small Organic Molecules.

    PubMed

    Zeng, Guang; Xing, Shanghua; Wang, Xiuru; Yang, Yulin; Ma, Dingxuan; Liang, Hongwei; Gao, Lu; Hua, Jia; Li, Guanghua; Shi, Zhan; Feng, Shouhua

    2016-02-01

    A 3d-4f luminescent metal-organic framework (MOF), [Tb2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (4), and three analogues {[La2(Cu8I8)(C12H8NO2)6(C4H8O2)2(H2O)2]·3C4H8O2·2H2O (1), [Ce2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (2), and [Eu2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (3)}, were self-assembled from copper(I) halide clusters and lanthanide metal ions with an organic linker [3-(pyridin-4-yl)benzoic acid] under solvothermal conditions. Compound 4 with high quantum yield (Φ = 68%) exhibits reversible luminescence behavior, accompanying the removal and recovery of guest molecules (1,4-dioxane). Because of the unique porous structure and dual luminescent centers of compound 4, it can efficiently differentiate benzene series with different sizes and provide readouts in corresponding optical signals. Furthermore, it also can unambiguously discriminate the isomers, homologues, and other small molecules with similar structural motifs from one another. The luminescent color of the MOF sensor in different guest solvents has obvious changes that can be clearly distinguished by the naked eye. This multicolor luminescence originates from emissions of the dual luminescent centers, and the emissions have shifted, enhanced, weakened, or quenched to different degrees.

  9. Visible absorption spectra of the 4f electron transitions of neodymium, praseodymium, holmium and erbium complexes with fleroxacin and their analytical application.

    PubMed

    Wang, Naixing; Jiang, Wei; Xu, Xiuqin; Si, Zhikun; Bai, Haitao; Tian, Cong

    2002-05-01

    The absorption spectra of the 4f electron transitions of neodymium, praseodymium, holmium and erbium complexes with fleroxacin in the presence of cetylpyridinium chloride were studied by normal and derivative spectrophotometry. Their molar absorptivity at the maximum absorption bands are about 5.3 (at 571 nm) times greater for neodymium, 2.8 (at 483 nm) times greater for praseodymium, 12.6 (at 448.5 nm) times greater for holmium and 9.7 (at 519 nm) times greater for erbium than those in the absence of complexing agents. The second-derivative spectrum is used both to eliminate the interference from other rare earths and to improve the sensitivity. Beer's law is obeyed from 3.0 - 70 microg ml(-1) for neodymium and holmium, from 6.0 - 70 microg ml(-1) for erbium, and from 12.0 - 70 microg ml(-1) for praseodymium. The relative standard deviations are 1.9% and 1.5% for 7.5 microg ml(-1) of neodymium and holmium, and 2.1% and 1.6% for 15.0 microg ml(-1) of praseodymium and erbium, respectively. Their detection limits (signal-to-noise ratio = 2) are 3.2 microg ml(-1), 1.3 microg ml(-1), (1.1) microg ml(-1) and 2.5 microg ml(-1) for praseodymium, neodymium, holmium and erbium, respectively. A new system for the simultaneous determinations of the praseodymium, neodymium, holmium and erbium in rare earth mixtures with good accuracy and selectivity is proposed.

  10. Mammalian target of rapamycin/eukaryotic initiation factor 4F pathway regulates follicle growth and development of theca cells in mice.

    PubMed

    Zhang, Chao; Liu, Xiao-Ran; Cao, Yong-Chun; Tian, Jin-Ling; Zhen, Di; Luo, Xiao-Fei; Wang, Xin-Mei; Tian, Jian-Hui; Gao, Jian-Ming

    2016-01-11

    The aim of the present study was to clarify the roles of the mammalian target of rapamycin (mTOR) signalling pathway in follicular growth and development of thecal cells. Using in vivo-grown and in vitro-cultured ovaries, histological changes were evaluated using haematoxylin and eosin (HE) staining. Differentially expressed genes (DEGs) from 0 day post partum (d.p.p.) to 8 d.p.p. ovaries were screened by microarray and verified by quantitative real-time polymerase chain reaction. Forty-two DEGs related to cell proliferation and differentiation were screened out, with most DEGs being related to the to mTOR signalling pathway. Then, 3 d.p.p. ovaries were retrieved and used to verify the role of mTOR signalling in follicle and thecal cell development using its activators (Ras homologue enriched in brain (Rheb) and GTP) and inhibitor (rapamycin). The development of follicles and thecal cells was significantly impaired in ovaries cultured in vitro Day 3 to Day 8. In in vitro-cultured ovaries, Rheb and GTP (is 100 ng mL-1 Rheb and 500 ng mL-1 GTP for 48 h) significantly increased follicle diameter, the percentage of primary and secondary follicles and the umber of thecal cells, and upregulated expression of mTOR, phosphorylated eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1), eukaryotic initiation factor (eIF) 4F and cytochrome P450, family 17, subfamily A, polypeptide 1 (CYP17A1). Rapamycin (10 nM rapamycin for 24 h) had opposite effects to those of Rheb and GTP, and partly abrogated (significant) the effects of Rheb and GTP when added to the culture in combination with these drugs. Thus, mTOR signalling plays an important role in follicle growth and thecal cell development.

  11. Tuning the Origin of Magnetic Relaxation by Substituting the 3d or Rare-Earth Ions into Three Isostructural Cyano-Bridged 3d-4f Heterodinuclear Compounds.

    PubMed

    Zhang, Yan; Guo, Zhen; Xie, Shuang; Li, Hui-Li; Zhu, Wen-Hua; Liu, Li; Dong, Xun-Qing; He, Wei-Xun; Ren, Jin-Chao; Liu, Ling-Zhi; Powell, Annie K

    2015-11-02

    Three isostructural cyano-bridged 3d-4f compounds, [YFe(CN)6(hep)2(H2O)4] (1), [DyFe(CN)6(hep)2(H2O)4] (2), and [DyCo(CN)6(hep)2(H2O)4] (3), were successfully assembled by site-targeted substitution of the 3d or rare-earth ions. All compounds have been structurally characterized to display slightly distorted pentagonal-bipyramidal local coordination geometry around the rare-earth ions. Magnetic analyses revealed negligible magnetic coupling in compound 1, antiferromagnetic intradimer interaction in 2, and weak ferromagnetic coupling through dipolar-dipolar interaction in 3. Under an applied direct-current (dc) field, 1 (Hdc = 2.5 kOe, τ0 = 1.3 × 10(-7) s, and Ueff/kB = 23 K) and 3 (Hdc = 2.0 kOe, τ0 = 7.1 × 10(-11) s, and Ueff/kB = 63 K) respectively indicated magnetic relaxation behavior based on a single [Fe(III)]LS ion and a Dy(III) ion; nevertheless, 2 (Hdc = 2.0 kOe, τ0 = 9.7 × 10(-8) s, and Ueff/kB = 23 K) appeared to be a single-molecule magnet based on a cyano-bridged DyFe dimer. Compound 1, which can be regarded as a single-ion magnet of the [Fe(III)]LS ion linked to a diamagnetic Y(III) ion in a cyano-bridged heterodimer, represents one of the rarely investigated examples based on a single Fe(III) ion explored in magnetic relaxation behavior. It demonstrated that the introduction of intradimer magnetic interaction of 2 through a cyano bridge between Dy(III) and [Fe(III)]LS ions negatively affects the energy barrier and χ″(T) peak temperature compared to 3.

  12. Translation directed by hepatitis A virus IRES in the absence of active eIF4F complex and eIF2.

    PubMed

    Redondo, Natalia; Sanz, Miguel Angel; Steinberger, Jutta; Skern, Tim; Kusov, Yuri; Carrasco, Luis

    2012-01-01

    Translation directed by several picornavirus IRES elements can usually take place after cleavage of eIF4G by picornavirus proteases 2A(pro) or L(pro). The hepatitis A virus (HAV) IRES is thought to be an exception to this rule because it requires intact eIF4F complex for translation. In line with previous results we report that poliovirus (PV) 2A(pro) strongly blocks protein synthesis directed by HAV IRES. However, in contrast to previous findings we now demonstrate that eIF4G cleavage by foot-and-mouth disease virus (FMDV) L(pro) strongly stimulates HAV IRES-driven translation. Thus, this is the first observation that 2A(pro) and L(pro) exhibit opposite effects to what was previously thought to be the case in HAV IRES. This effect has been observed both in hamster BHK and human hepatoma Huh7 cells. In addition, this stimulation of translation is also observed in cell free systems after addition of purified L(pro). Notably, in presence of this FMDV protease, translation directed by HAV IRES takes place when eIF2α has been inactivated by phosphorylation. Our present findings clearly demonstrate that protein synthesis directed by HAV IRES can occur when eIF4G has been cleaved and after inactivation of eIF2. Therefore, translation directed by HAV IRES without intact eIF4G and active eIF2 is similar to that observed with other picornavirus IRESs.

  13. Core sample extractor

    NASA Technical Reports Server (NTRS)

    Akins, James; Cobb, Billy; Hart, Steve; Leaptrotte, Jeff; Milhollin, James; Pernik, Mark

    1989-01-01

    The problem of retrieving and storing core samples from a hole drilled on the lunar surface is addressed. The total depth of the hole in question is 50 meters with a maximum diameter of 100 millimeters. The core sample itself has a diameter of 60 millimeters and will be two meters in length. It is therefore necessary to retrieve and store 25 core samples per hole. The design utilizes a control system that will stop the mechanism at a certain depth, a cam-linkage system that will fracture the core, and a storage system that will save and catalogue the cores to be extracted. The Rod Changer and Storage Design Group will provide the necessary tooling to get into the hole as well as to the core. The mechanical design for the cam-linkage system as well as the conceptual design of the storage device are described.

  14. Studies on the complexation of neodymium(III) ion with 1,2,4-1H-triazole and 1,2,3-benzotriazole in absence and presence of calcium(II) ion in aqueous and some selected different aquated organic solvents by an absorption spectroscopy involving 4f-4f transitions.

    PubMed

    Huidrom, Bimola; Ranjana Devi, N; Singh, Th David; Singh, N Rajmuhon

    2012-01-01

    The absorption spectra of trivalent neodymium ion with 1,2,4-1H-triazole and 1,2,3-benzotriazole in absence and presence of calcium(II) ion in aqueous and some selected different aquated organic solvents have been recorded in the visible and near infrared regions. From the data available in the absorption spectra, various spectroscopic parameters such as Slator-Condon (F(k)), Lande spin-orbit coupling constant (ξ(4f)), nephelauxetic ratio (β), bonding parameter (b(1/2)), percent covalency (δ), oscillator strength (P) and Judd-Ofelt intensity (T(λ)) parameters have been evaluated. The Judd-Ofelt intensity, T(λ) (λ=2, 4, 6) parameters are utilized in evaluating the P(cal) from various excited states of trivalent neodymium ions and ratifying as an inner sphere complexations.

  15. The core paradox.

    NASA Technical Reports Server (NTRS)

    Kennedy, G. C.; Higgins, G. H.

    1973-01-01

    Rebuttal of suggestions from various critics attempting to provide an escape from the seeming paradox originated by Higgins and Kennedy's (1971) proposed possibility that the liquid in the outer core was thermally stably stratified and that this stratification might prove a powerful inhibitor to circulation of the outer core fluid of the kind postulated for the generation of the earth's magnetic field. These suggestions are examined and shown to provide no reasonable escape from the core paradox.

  16. Core Research Center

    USGS Publications Warehouse

    Hicks, Joshua; Adrian, Betty

    2009-01-01

    The Core Research Center (CRC) of the U.S. Geological Survey (USGS), located at the Denver Federal Center in Lakewood, Colo., currently houses rock core from more than 8,500 boreholes representing about 1.7 million feet of rock core from 35 States and cuttings from 54,000 boreholes representing 238 million feet of drilling in 28 States. Although most of the boreholes are located in the Rocky Mountain region, the geologic and geographic diversity of samples have helped the CRC become one of the largest and most heavily used public core repositories in the United States. Many of the boreholes represented in the collection were drilled for energy and mineral exploration, and many of the cores and cuttings were donated to the CRC by private companies in these industries. Some cores and cuttings were collected by the USGS along with other government agencies. Approximately one-half of the cores are slabbed and photographed. More than 18,000 thin sections and a large volume of analytical data from the cores and cuttings are also accessible. A growing collection of digital images of the cores are also becoming available on the CRC Web site Internet http://geology.cr.usgs.gov/crc/.

  17. In Situ Studies of Surface Mobility on Noble Metal Model Catalysts Using STM and XPS at Ambient Pressure

    SciTech Connect

    Butcher, Derek Robert

    2010-06-01

    High Pressure Scanning Tunneling Microscopy (HP-STM) and Ambient Pressure X-ray Photoelectron Spectroscopy were used to study the structural properties and catalytic behavior of noble metal surfaces at high pressure. HP-STM was used to study the structural rearrangement of the top most atomic surface layer of the metal surfaces in response to changes in gas pressure and reactive conditions. AP-XPS was applied to single crystal and nanoparticle systems to monitor changes in the chemical composition of the surface layer in response to changing gas conditions. STM studies on the Pt(100) crystal face showed the lifting of the Pt(100)-hex surface reconstruction in the presence of CO, H2, and Benzene. The gas adsorption and subsequent charge transfer relieves the surface strain caused by the low coordination number of the (100) surface atoms allowing the formation of a (1 x 1) surface structure commensurate with the bulk terminated crystal structure. The surface phase change causes a transformation of the surface layer from hexagonal packing geometry to a four-fold symmetric surface which is rich in atomic defects. Lifting the hex reconstruction at room temperature resulted in a surface structure decorated with 2-3 nm Pt adatom islands with a high density of step edge sites. Annealing the surface at a modest temperature (150 C) in the presence of a high pressure of CO or H2 increased the surface diffusion of the Pt atoms causing the adatom islands to aggregate reducing the surface concentration of low coordination defect sites. Ethylene hydrogenation was studied on the Pt(100) surface using HP-STM. At low pressure, the lifting of the hex reconstruction was observed in the STM images. Increasing the ethylene pressure to 1 Torr, was found to regenerate the hexagonally symmetric reconstructed phase. At room temperature ethylene undergoes a structural rearrangement to form ethylidyne. Ethylidyne preferentially binds at the three-fold hollow sites, which

  18. Can Psychiatric Rehabilitation Be Core to CORE?

    ERIC Educational Resources Information Center

    Olney, Marjorie F.; Gill, Kenneth J.

    2016-01-01

    Purpose: In this article, we seek to determine whether psychiatric rehabilitation principles and practices have been more fully incorporated into the Council on Rehabilitation Education (CORE) standards, the extent to which they are covered in four rehabilitation counseling "foundations" textbooks, and how they are reflected in the…

  19. Fast‐Rate Capable Electrode Material with Higher Energy Density than LiFePO4: 4.2V LiVPO4F Synthesized by Scalable Single‐Step Solid‐State Reaction

    PubMed Central

    Kim, Minkyung; Lee, Seongsu

    2015-01-01

    Use of compounds that contain fluorine (F) as electrode materials in lithium ion batteries has been considered, but synthesizing single‐phase samples of these compounds is a difficult task. Here, it is demonstrated that a simple scalable single‐step solid‐state process with additional fluorine source can obtain highly pure LiVPO4F. The resulting material with submicron particles achieves very high rate capability ≈100 mAh g−1 at 60 C‐rate (1‐min discharge) and even at 200 C‐rate (18 s discharge). It retains superior capacity, ≈120 mAh g−1 at 10 C charge/10 C discharge rate (6‐min) for 500 cycles with >95% retention efficiency. Furthermore, LiVPO4F shows low polarization even at high rates leading to higher operating potential >3.45 V (≈3.6 V at 60 C‐rate), so it achieves high energy density. It is demonstrated for the first time that highly pure LiVPO4F can achieve high power capability comparable to LiFePO4 and much higher energy density (≈521 Wh g−1 at 20 C‐rate) than LiFePO4 even without nanostructured particles. LiVPO4F can be a real substitute of LiFePO4. PMID:27774395

  20. Fast-Rate Capable Electrode Material with Higher Energy Density than LiFePO4: 4.2V LiVPO4F Synthesized by Scalable Single-Step Solid-State Reaction.

    PubMed

    Kim, Minkyung; Lee, Seongsu; Kang, Byoungwoo

    2016-03-01

    Use of compounds that contain fluorine (F) as electrode materials in lithium ion batteries has been considered, but synthesizing single-phase samples of these compounds is a difficult task. Here, it is demonstrated that a simple scalable single-step solid-state process with additional fluorine source can obtain highly pure LiVPO4F. The resulting material with submicron particles achieves very high rate capability ≈100 mAh g(-1) at 60 C-rate (1-min discharge) and even at 200 C-rate (18 s discharge). It retains superior capacity, ≈120 mAh g(-1) at 10 C charge/10 C discharge rate (6-min) for 500 cycles with >95% retention efficiency. Furthermore, LiVPO4F shows low polarization even at high rates leading to higher operating potential >3.45 V (≈3.6 V at 60 C-rate), so it achieves high energy density. It is demonstrated for the first time that highly pure LiVPO4F can achieve high power capability comparable to LiFePO4 and much higher energy density (≈521 Wh g(-1) at 20 C-rate) than LiFePO4 even without nanostructured particles. LiVPO4F can be a real substitute of LiFePO4.

  1. Thermal ionization and thermally activated crossover quenching processes for 5 d -4 f luminescence in Y3A l5 -xG axO12:P r3 +

    NASA Astrophysics Data System (ADS)

    Ueda, Jumpei; Meijerink, Andries; Dorenbos, Pieter; Bos, Adrie J. J.; Tanabe, Setsuhisa

    2017-01-01

    We investigated thermally activated ionization and thermally activated crossover as the two possibilities of quenching of 5 d luminescence in P r3 + -doped Y3A l5 -xG axO12 . Varying the Ga content x gives the control over the relative energy level location of the 5 d and 4 f2:P3J states of P r3 + and the host conduction band (CB). Temperature-dependent luminescence lifetime measurements show that the 5 d luminescence quenching temperature T50 % increases up to x =2 and decreases with further increasing Ga content. This peculiar behavior is explained by a unique transition between the two quenching mechanisms which have an opposite dependence of thermal quenching on Ga content. For low Ga content, thermally activated crossover from the 4 f 5 d state to the 4 f2(P3J) states is the operative quenching mechanism. With increasing Ga content, the activation energy for thermally activated crossover becomes larger, as derived from the configuration coordinate diagram, while from the vacuum referred binding energy diagram the activation energy of thermal ionization becomes smaller. Based on these results, we demonstrated that the thermal quenching of P r3 +:5 d1-4 f luminescence in Y3A l5 -xG axO12 with x =0 ,1 ,2 is a thermally activated crossover while for x =3 ,4 ,5 it results from the thermal ionization.

  2. Ultralarge 3d/4f Coordination Wheels: From Carboxylate/Amino Alcohol-Supported {Fe4Ln2} to {Fe18Ln6} Rings

    PubMed Central

    2017-01-01

    A family of wheel-shaped charge-neutral heterometallic {FeIII4LnIII2}- and {FeIII18MIII6}-type coordination clusters demonstrates the intricate interplay of solvent effects and structure-directing roles of semiflexible bridging ligands. The {Fe4Ln2}-type compounds [Fe4Ln2(O2CCMe3)6(N3)4(Htea)4]·2(EtOH), Ln = Dy (1a), Er (1b), Ho (1c); [Fe4Tb2(O2CCMe3)6(N3)4(Htea)4] (1d); [Fe4Ln2(O2CCMe3)6(N3)4(Htea)4]·2(CH2Cl2), Ln = Dy (2a), Er (2b); [Fe4Ln2(O2CCMe3)4(N3)6(Htea)4]·2(EtOH)·2(CH2Cl2), Ln = Dy (3a), Er (3b) and the {Fe18M6}-type compounds [Fe18M6(O2CCHMe2)12(Htea)18(tea)6(N3)6]·n(solvent), M = Dy (4, 4a), Gd (5), Tb (6), Ho (7), Sm (8), Eu (9), and Y (10) form in ca. 20–40% yields in direct reaction of trinuclear FeIII pivalate or isobutyrate clusters, lanthanide/yttrium nitrates, and bridging triethanolamine (H3tea) and azide ligands in different solvents: EtOH for the smaller {Fe4Ln2} wheels and MeOH/MeCN or MeOH/EtOH for the larger {Fe18M6} wheels. Single-crystal X-ray diffraction analyses revealed that 1–3 consist of planar centrosymmetric hexanuclear clusters built from FeIII and LnIII ions linked by an array of bridging carboxylate, azide, and aminopolyalcoholato-based ligands into a cyclic structure with a cavity, and with distinct sets of crystal solvents (2 EtOH per formula unit in 1a–c, 2 CH2Cl2 in 2, and 2 EtOH and 2 CH2Cl2 in 3). In 4–10, the largest 3d/4f wheels currently known, nearly linear Fe3 fragments are joined via mononuclear Ln/Y units by a set of isobutyrates and amino alcohol ligands into virtually planar rings. The magnetic properties of 1–10 reveal slow magnetization relaxation for {Fe4Tb2} (1d) and slow relaxation for {Fe4Ho2} (1c), {Fe18Dy6} (4), and {Fe18Tb6} (6). PMID:28135085

  3. Core-Hole Effect in the Ce L3 X-Ray Absorption Spectra of CeO2 and CeFe2: New Examination by Using Resonant X-Ray Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kotani, A.

    2013-06-01

    We consider two different resonant X-ray emission spectra for Ce compounds: Ce 3d to 2p X-ray emission (denoted by 3d-RXES) and valence to 2p X-ray emission (v-RXES), both of which follow the Ce 2p to 5d resonant excitation. We propose that the comparison of the 3d- and v-RXES spectra is a new powerful method of directly detecting the core-hole effect in the final state of Ce L3 X-ray absorption spectra (XAS). We applied this method to recent experimental RXES spectra for CeO2 and CeFe2, and showed unambiguously that the core-hole effect should be essential in the XAS of both materials. This result is confirmed by theoretical calculations, which reproduce well the experimental RXES and XAS spectra. We conclude that the ground state of CeO2 is in the mixed state of 4f0 and 4f1_{L} configurations, where _{L} is a ligand hole, instead of a pure 4f0 configuration which was proposed recently by first-principles energy band calculations. Also, we conclude that the double peaks observed in L3 XAS of CeFe2 are caused by the 4f0 and 4f1 configurations, which are mixed in the ground state but separated in energy by the large core-hole potential in the final state of XAS.

  4. Location of Varying Hydrophobicity Zinc(II) Phthalocyanine-Type Photosensitizers in Methoxy Poly(ethylene oxide) and Poly(l-lactide) Block Copolymer Micelles Using (1)H NMR and XPS Techniques.

    PubMed

    Lamch, Łukasz; Tylus, Włodzimierz; Jewgiński, Michał; Latajka, Rafał; Wilk, Kazimiera A

    2016-12-15

    Hydrophobic zinc(II) phthalocyanine-type derivatives, solubilized in polymeric micelles (PMs), provide a befitting group of so-called nanophotosensitizers, suitable for a variety of photodynamic therapy (PDT) protocols. The factors that influence the success of such products in PDT are the location of the active cargo in the PMs and the nanocarrier-enhanced ability to safely interact with biological systems and fulfill their therapeutic functions. Therefore, the aim of this work was to determine the solubilization loci of three phthalocyanines of varying hydrophobicity, i.e., zinc(II) phthalocyanine (ZnPc), along with its tetrasulfonic acid (ZnPc-sulfo4) and perfluorinated (ZnPcF16) derivatives, loaded in polymeric micelles of methoxy poly(ethylene oxide)-b-poly(l-lactide) (mPEG-b-PLLA), by means of (1)H nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) combined with ion sputtering. Furthermore, the microenvironment influence upon the chemical and physical status of the solubilized cargo in PMs, expressed by photobleaching and reactive oxygen species (ROS) generation comparing to the same properties of native cargoes in solution, was also evaluated and discussed in regards to the probing location data. The studied phthalocyanine-loaded PMs exhibited good physical stability, high drug-loading efficiency, and a size of less than ca. 150 nm with low polydispersity indices. The formation of polymeric micelles and the solubilization locus were investigated by (1)H NMR and XPS. ZnPc localized within the PM core, whereas both ZnPcF16 and ZnPc-sulfo4 - in the corona of PMs. We proved that the cargo locus is crucial for the photochemical properties of the studied phthalocyanines; the increase in photostability and ability to generate ROS in micellar solution compared to free photosensitizer was most significant for the photosensitizer in the PM core. Our results indicate the role of the cargo location in the PM microenvironment and demonstrate that

  5. Making an Ice Core.

    ERIC Educational Resources Information Center

    Kopaska-Merkel, David C.

    1995-01-01

    Explains an activity in which students construct a simulated ice core. Materials required include only a freezer, food coloring, a bottle, and water. This hands-on exercise demonstrates how a glacier is formed, how ice cores are studied, and the nature of precision and accuracy in measurement. Suitable for grades three through eight. (Author/PVD)

  6. Core Concepts of Kinesiology.

    ERIC Educational Resources Information Center

    Hudson, Jackie L.

    1995-01-01

    Core concepts of kinesiology are the basis of communication about movement that facilitate progression of skill levels. The article defines and exemplifies each of 10 core concepts: range of motion, speed of motion, number of segments, nature of segments, balance, coordination, compactness, extension at release/contact, path of projection, and…

  7. CORE - Performance Feedback System

    SciTech Connect

    2009-10-02

    CORE is an architecture to bridge the gaps between disparate data integration and delivery of disparate information visualization. The CORE Technology Program includes a suite of tools and user-centered staff that can facilitate rapid delivery of a deployable integrated information to users.

  8. Iowa Core Annual Report

    ERIC Educational Resources Information Center

    Iowa Department of Education, 2015

    2015-01-01

    One central component of a great school system is a clear set of expectations, or standards, that educators help all students reach. In Iowa, that effort is known as the Iowa Core. The Iowa Core represents the statewide academic standards, which describe what students should know and be able to do in math, science, English language arts, and…

  9. Ice Core Investigations

    ERIC Educational Resources Information Center

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  10. Modular core holder

    SciTech Connect

    Mueller, J.; Cole, C.W.; Hamid, S.; Lucas, J.K.

    1991-03-05

    This patent describes a modular core holder. It comprises: a sleeve, forming an internal cavity for receiving a core. The sleeve including segments; support means, overlying the sleeve, for supporting the sleeve; and access means, positioned between at least two of the segments of the sleeve, for allowing measurement of conditions within the internal cavity.

  11. More on the Core

    ERIC Educational Resources Information Center

    Chan, Monnica

    2013-01-01

    From a higher education perspective, new "Common Core" standards could improve student college-readiness levels, reduce institutional remediation rates, and close education gaps in and between states. As a national initiative to create common educational standards for students across multiple states, the Common Core State Standards…

  12. Mercury's core evolution

    NASA Astrophysics Data System (ADS)

    Deproost, Marie-Hélène; Rivoldini, Attilio; Van Hoolst, Tim

    2016-10-01

    Remote sensing data of Mercury's surface by MESSENGER indicate that Mercury formed under reducing conditions. As a consequence, silicon is likely the main light element in the core together with a possible small fraction of sulfur. Compared to sulfur, which does almost not partition into solid iron at Mercury's core conditions and strongly decreases the melting temperature, silicon partitions almost equally well between solid and liquid iron and is not very effective at reducing the melting temperature of iron. Silicon as the major light element constituent instead of sulfur therefore implies a significantly higher core liquidus temperature and a decrease in the vigor of compositional convection generated by the release of light elements upon inner core formation.Due to the immiscibility in liquid Fe-Si-S at low pressure (below 15 GPa), the core might also not be homogeneous and consist of an inner S-poor Fe-Si core below a thinner Si-poor Fe-S layer. Here, we study the consequences of a silicon-rich core and the effect of the blanketing Fe-S layer on the thermal evolution of Mercury's core and on the generation of a magnetic field.

  13. NFE Core Bibliographies.

    ERIC Educational Resources Information Center

    Michigan State Univ., East Lansing. Inst. for International Studies in Education.

    This collection of core bibliographies, which expands on an initial bibliography published in 1979 of the core resources housed in the Non-Formal Education Information Center at Michigan State University, comprises a basic stock of materials on nonformal education and women in development that have been contributed by development planners,…

  14. Phase equilibria in the NaF-CdO-NaPO3 system at 873 K and crystal structure and physico-chemical characterizations of the new Na2CdPO4F fluorophosphate

    NASA Astrophysics Data System (ADS)

    Aboussatar, Mohamed; Mbarek, Aïcha; Naili, Houcine; El-Ghozzi, Malika; Chadeyron, Geneviève; Avignant, Daniel; Zambon, Daniel

    2017-04-01

    Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO3 system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO4 side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na2CdPO4F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1), c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na2CaPO4F and the fluorosilicate Ca2NaSiO4F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na2MIIPO4F (MII=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and 19F, 23Na, 31P MAS NMR characterizations of Na2CdPO4F have been investigated.

  15. Surface Coverage and Structure of Mixed DNA/Alkylthiol Monolayers on Gold: Characterization by XPS, NEXAFS, and Fluorescence Intensity Measurements

    PubMed Central

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

    2006-01-01

    Self-assembly of thiol-terminated single-stranded DNA (HS-ssDNA) on gold has served as an important model system for DNA immobilization at surfaces. Here, we report a detailed study of the surface composition and structure of mixed self-assembled DNA monolayers containing a short alkylthiol surface diluent [11-mercapto-1-undecanol (MCU)] on gold supports. These mixed DNA monolayers were studied with X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and fluorescence intensity measurements. XPS results on sequentially adsorbed DNA/MCU monolayers on gold indicated that adsorbed MCU molecules first incorporate into the HS-ssDNA monolayer and, upon longer MCU exposures, displace adsorbed HS-ssDNA molecules from the surface. Thus, HS-ssDNA surface coverage steadily decreased with MCU exposure time. Polarization-dependent NEXAFS and fluorescence results both show changes in signals consistent with changes in DNA orientation after only 30 min of MCU exposure. NEXAFS polarization dependence (followed by monitoring the N 1s → π* transition) of the mixed DNA monolayers indicated that the DNA nucleotide base ring structures are oriented more parallel to the gold surface compared to DNA bases in pure HS-ssDNA monolayers. This indicates that HS-ssDNA oligomers reorient toward a more-upright position upon MCU incorporation. Fluorescence intensity results using end-labeled DNA probes on gold show little observable fluorescence on pure HS-ssDNA monolayers, likely due to substrate quenching effects between the fluorophore and the gold. MCU diluent incorporation into HS-ssDNA monolayers initially increases DNA fluorescence signal by densifying the chemisorbed monolayer, prompting an upright orientation of the DNA, and moving the terminal fluorophore away from the substrate. Immobilized DNA probe density and DNA target hybridization in these mixed DNA monolayers, as well as effects of MCU diluent on DNA hybridization in complex

  16. Surface Coverage and Structure of Mixed DNA/Alkylthiol Monolayers on Gold: Characterization by XPS, NEXAFS, and Fluorescence Intensity Measurements

    SciTech Connect

    Lee,C.; Gong, P.; Harbers, G.; Grainger, D.; Castner, D.; Gamble, L.

    2006-01-01

    Self-assembly of thiol-terminated single-stranded DNA (HS-ssDNA) on gold has served as an important model system for DNA immobilization at surfaces. Here, we report a detailed study of the surface composition and structure of mixed self-assembled DNA monolayers containing a short alkylthiol surface diluent [11-mercapto-1-undecanol (MCU)] on gold supports. These mixed DNA monolayers were studied with X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and fluorescence intensity measurements. XPS results on sequentially adsorbed DNA/MCU monolayers on gold indicated that adsorbed MCU molecules first incorporate into the HS-ssDNA monolayer and, upon longer MCU exposures, displace adsorbed HS-ssDNA molecules from the surface. Thus, HS-ssDNA surface coverage steadily decreased with MCU exposure time. Polarization-dependent NEXAFS and fluorescence results both show changes in signals consistent with changes in DNA orientation after only 30 min of MCU exposure. NEXAFS polarization dependence (followed by monitoring the N 1s{yields}{pi}* transition) of the mixed DNA monolayers indicated that the DNA nucleotide base ring structures are oriented more parallel to the gold surface compared to DNA bases in pure HS-ssDNA monolayers. This indicates that HS-ssDNA oligomers reorient toward a more-upright position upon MCU incorporation. Fluorescence intensity results using end-labeled DNA probes on gold show little observable fluorescence on pure HS-ssDNA monolayers, likely due to substrate quenching effects between the fluorophore and the gold. MCU diluent incorporation into HS-ssDNA monolayers initially increases DNA fluorescence signal by densifying the chemisorbed monolayer, prompting an upright orientation of the DNA, and moving the terminal fluorophore away from the substrate. Immobilized DNA probe density and DNA target hybridization in these mixed DNA monolayers, as well as effects of MCU diluent on DNA hybridization in

  17. XPS study of reductive dissolution of birnessite by oxalate: Rates and mechanistic aspects of dissolution and redox processes

    SciTech Connect

    Banerjee, D.; Nesbitt, H.W.

    1999-10-01

    Reductive dissolution of synthetic 7{angstrom}-birnessite [MnO{sub 1.7}(OH){sub 0.25} or MnO{sub 1.95}] by Na-oxalate produces a Mn(III) intermediate reaction product (here represented as MnOOH) which subsequently reacts with sorbed (COO){sub 2}{sup {minus}2} to form an unreactive Mn(III)-oxalate surface complex at the solution-mineral interface. X-ray Photoelectron Spectroscopy (XPS) results from Mn2p{sub 3/2}, C1s and O1s spectra of reacted surfaces reveal that initially rapid production of CO{sub 2} results in accumulation of CO{sub 2} at the reaction interface. After about 15 min, the reaction rate decreases to the point where CO{sub 2} desorption keeps pace with accumulation. Surface concentrations of CO{sub 2} suggest that the rate of CO{sub 2} production decreases with time, until after 10 hr of reaction, it is undetectable. Reduction of Mn(IV) to Mn(III) suggests that the MnO{sub 2}-oxalate redox reaction proceeds as a transfer of one electron per metal center. There is no XPS evidence for reduction of Mn(III) from birnessite to Mn(II) in the presence of oxalate. Although this reaction proceeds in presence of arsenite, it is inhibited by oxalate, probably through formation of a strong Mn(III)-oxalate surface complex (either monodentate or bidentate). This hypothesis is consistent with Mn{sup 3+} (aq) stabilization by oxalate in aqueous solutions. Further study using X-ray absorption spectroscopy (XAS) is required for a better understanding of the structure of the surface complexes. Rate of release of soluble Mn(II) to dilute oxalate solutions (5 x 10{sup {minus}4} M) is lower by an order of magnitude than the rate of release to aerated, distilled water at similar pH. Apparently, the process of proton-promoted dissolution of the soluble Mn(II) component of birnessite in distilled water is impeded by the addition of oxalate, probably by formation of a binuclear, bidentate surface complex between Mn(II, III) and adsorbed oxalate ions.

  18. Internal core tightener

    DOEpatents

    Brynsvold, Glen V.; Snyder, Jr., Harold J.

    1976-06-22

    An internal core tightener which is a linear actuated (vertical actuation motion) expanding device utilizing a minimum of moving parts to perform the lateral tightening function. The key features are: (1) large contact areas to transmit loads during reactor operation; (2) actuation cam surfaces loaded only during clamping and unclamping operation; (3) separation of the parts and internal operation involved in the holding function from those involved in the actuation function; and (4) preloaded pads with compliant travel at each face of the hexagonal assembly at the two clamping planes to accommodate thermal expansion and irradiation induced swelling. The latter feature enables use of a "fixed" outer core boundary, and thus eliminates the uncertainty in gross core dimensions, and potential for rapid core reactivity changes as a result of core dimensional change.

  19. Lunar Core and Tides

    NASA Technical Reports Server (NTRS)

    Williams, J. G.; Boggs, D. H.; Ratcliff, J. T.

    2004-01-01

    Variations in rotation and orientation of the Moon are sensitive to solid-body tidal dissipation, dissipation due to relative motion at the fluid-core/solid-mantle boundary, and tidal Love number k2 [1,2]. There is weaker sensitivity to flattening of the core-mantle boundary (CMB) [2,3,4] and fluid core moment of inertia [1]. Accurate Lunar Laser Ranging (LLR) measurements of the distance from observatories on the Earth to four retroreflector arrays on the Moon are sensitive to lunar rotation and orientation variations and tidal displacements. Past solutions using the LLR data have given results for dissipation due to solid-body tides and fluid core [1] plus Love number [1-5]. Detection of CMB flattening, which in the past has been marginal but improving [3,4,5], now seems significant. Direct detection of the core moment has not yet been achieved.

  20. Design of an in-house ambient pressure AP-XPS using a bench-top X-ray source and the surface chemistry of ceria under reaction conditions.

    PubMed

    Tao, Franklin Feng

    2012-04-21

    A new in-house ambient pressure XPS (AP-XPS) was designed for the study of surfaces of materials under reaction conditions and during catalysis. Unique features of this in-house AP-XPS are the use of monochromated Al Kα and integration of a minimized reaction cell, and working conditions of up to 500 °C in gases of tens of Torr. Generation of oxygen vacancies on ceria and filling them with oxygen atoms were characterized in operando.

  1. A comparative theoretical study on core-hole excitation spectra of azafullerene and its derivatives

    SciTech Connect

    Deng, Yunfeng; Gao, Bin; Deng, Mingsen; Luo, Yi

    2014-03-28

    The core-hole excitation spectra—near-edge x-ray absorption spectroscopy (NEXAFS), x-ray emission spectroscopy (XES), and x-ray photoelectron spectroscopy (XPS) shake-up satellites have been simulated at the level of density functional theory for the azafullerene C{sub 59}N and its derivatives (C{sub 59}N){sup +}, C{sub 59}HN, (C{sub 59}N){sub 2}, and C{sub 59}N–C{sub 60}, in which the XPS shake-up satellites were simulated using our developed equivalent core hole Kohn-Sham (ECH-KS) density functional theory approach [B. Gao, Z. Wu, and Y. Luo, J. Chem. Phys. 128, 234704 (2008)] which aims for the study of XPS shake-up satellites of large-scale molecules. Our calculated spectra are generally in good agreement with available experimental results that validates the use of the ECH-KS method in the present work. The nitrogen K-edge NEXAFS, XES, and XPS shake-up satellites spectra in general can be used as fingerprints to distinguish the azafullerene C{sub 59}N and its different derivatives. Meanwhile, different carbon K-edge spectra could also provide detailed information of (local) electronic structures of different molecules. In particular, a peak (at around 284.5 eV) in the carbon K-edge NEXAFS spectrum of the heterodimer C{sub 59}N–C{sub 60} is confirmed to be related to the electron transfer from the C{sub 59}N part to the C{sub 60} part in this charge-transfer complex.

  2. 34. DESPATCH CORE OVENS, GREY IRON FOUNDRY CORE ROOM, BAKES ...

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

    34. DESPATCH CORE OVENS, GREY IRON FOUNDRY CORE ROOM, BAKES CORES THAT ARE NOT MADE ON HEATED OR COLD BOX CORE MACHINES, TO SET BINDING AGENTS MIXED WITH THE SAND CREATING CORES HARD ENOUGH TO WITHSTAND THE FLOW OF MOLTEN IRON INSIDE A MOLD. - Stockham Pipe & Fittings Company, Grey Iron Foundry, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  3. Quantitative analysis of Fe and Co in Co-substituted magnetite using XPS: The application of non-linear least squares fitting (NLLSF)

    NASA Astrophysics Data System (ADS)

    Liu, Hongmei; Wei, Gaoling; Xu, Zhen; Liu, Peng; Li, Ying

    2016-12-01

    Quantitative analysis of Co and Fe using X-ray photoelectron spectroscopy (XPS) is of important for the evaluation of the catalytic ability of Co-substituted magnetite. However, the overlap of XPS peaks and Auger peaks for Co and Fe complicate quantification. In this study, non-linear least squares fitting (NLLSF) was used to calculate the relative Co and Fe contents of a series of synthesized Co-substituted magnetite samples with different Co doping levels. NLLSF separated the XPS peaks of Co 2p and Fe 2p from the Auger peaks of Fe and Co, respectively. Compared with a control group without fitting, the accuracy of quantification of Co and Fe was greatly improved after elimination by NLLSF of the disturbance of Auger peaks. A catalysis study confirmed that the catalytic activity of magnetite was enhanced with the increase of Co substitution. This study confirms the effectiveness and accuracy of the NLLSF method in XPS quantitative calculation of Fe and Co coexisting in a material.

  4. 13C NMR and XPS characterization of anion adsorbent with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse

    NASA Astrophysics Data System (ADS)

    Cao, Wei; Wang, Zhenqian; Zeng, Qingling; Shen, Chunhua

    2016-12-01

    Despite amino groups modified crop straw has been intensively studied as new and low-cost adsorbent for removal of anionic species from water, there is still a lack of clear characterization for amino groups, especially quaternary ammonium groups in the surface of crop straw. In this study, we used 13C NMR and XPS technologies to characterize adsorbents with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse. 13C NMR spectra clearly showed the presence of quaternary ammonium groups in lignocelluloses structure of modified crop straw. The increase of nitrogen observed in XPS survey spectra also indicated the existence of quaternary ammonium group in the surface of the adsorbents. The curve fitting of high-resolution XPS N1s and C1s spectra were conducted to probe the composition of nitrogen and carbon contained groups, respectively. The results showed the proportion of quaternary ammonium group significantly increased in the prepared adsorbent's surface that was dominated by methyl/methylene, hydroxyl, quaternary ammonium, ether and carbonyl groups. This study proved that 13C NMR and XPS could be successfully utilized for characterization of quaternary ammonium modified crop straw adsorbents.

  5. Vacuum annealing phenomena in ultrathin TiDy/Pd bi-layer films evaporated on Si(100) as studied by TEM and XPS.

    PubMed

    Lisowski, W; Keim, E G

    2010-04-01

    Using a combination of TEM and XPS, we made an analysis of the complex high-temperature annealing effect on ultrathin titanium deuteride (TiD(y)) films evaporated on a Si(100) substrate and covered by an ultrathin palladium layer. Both the preparation and annealing of the TiD(y)/Pd bi-layer films were performed in situ under UHV conditions. It was found that the surface and bulk morphology of the bi-layer film as well as that of the Si substrate material undergo a microstructural and chemical conversion after annealing and annealing-induced deuterium evolution from the TiD(y) phase. Energy-filtered TEM (EFTEM) mapping of cross-section images and argon ion sputter depth profiling XPS analysis revealed both a broad intermixing between the Ti and Pd layers and an extensive inter-diffusion of Si from the substrate into the film bulk area. Segregation of Ti at the Pd top layer surface was found to occur by means of angle-resolved XPS (ARXPS) and the EFTEM analyses. Selected area diffraction (SAD) and XPS provided evidence for the formation of a new PdTi(2) bimetallic phase within the top region of the annealed film. Moreover, these techniques allowed to detect the initial stages of TiSi phase formation within the film-substrate interlayer.

  6. Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS.

    PubMed

    Belsey, Natalie A; Cant, David J H; Minelli, Caterina; Araujo, Joyce R; Bock, Bernd; Brüner, Philipp; Castner, David G; Ceccone, Giacomo; Counsell, Jonathan D P; Dietrich, Paul M; Engelhard, Mark H; Fearn, Sarah; Galhardo, Carlos E; Kalbe, Henryk; Won Kim, Jeong; Lartundo-Rojas, Luis; Luftman, Henry S; Nunney, Tim S; Pseiner, Johannes; Smith, Emily F; Spampinato, Valentina; Sturm, Jacobus M; Thomas, Andrew G; Treacy, Jon P W; Veith, Lothar; Wagstaffe, Michael; Wang, Hai; Wang, Meiling; Wang, Yung-Chen; Werner, Wolfgang; Yang, Li; Shard, Alexander G

    2016-10-27

    We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage or sample preparation resulted in a variability in thickness of 53 %. The calculation method chosen by XPS participants contributed a variability of 67 %. However, variability of 12 % was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors, since this contributed a variability of 33 %. The results from the LEIS participants were more consistent, with variability of less than 10 % in thickness and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

  7. Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS

    SciTech Connect

    Belsey, Natalie A.; Cant, David J. H.; Minelli, Caterina; Araujo, Joyce R.; Bock, Bernd; Brüner, Philipp; Castner, David G.; Ceccone, Giacomo; Counsell, Jonathan D. P.; Dietrich, Paul M.; Engelhard, Mark H.; Fearn, Sarah; Galhardo, Carlos E.; Kalbe, Henryk; Kim, Jeong Won; Lartundo-Rojas, Luis; Luftman, Henry S.; Nunney, Tim S.; Pseiner, Johannes; Smith, Emily F.; Spampinato, Valentina; Sturm, Jacobus M.; Thomas, Andrew G.; Treacy, Jon P. W.; Veith, Lothar; Wagstaffe, Michael; Wang, Hai; Wang, Meiling; Wang, Yung-Chen; Werner, Wolfgang; Yang, Li; Shard, Alexander G.

    2016-10-27

    We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage or sample preparation resulted in a variability in thickness of 53 %. The calculation method chosen by XPS participants contributed a variability of 67 %. However, variability of 12 % was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors, since this contributed a variability of 33 %. The results from the LEIS participants were more consistent, with variability of less than 10 % in thickness and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

  8. XPS and EELS characterization of Mn2SiO4, MnSiO3 and MnAl2O4

    NASA Astrophysics Data System (ADS)

    Grosvenor, A. P.; Bellhouse, E. M.; Korinek, A.; Bugnet, M.; McDermid, J. R.

    2016-08-01

    X-ray Photoelectron Spectroscopy (XPS) and Electron Energy Loss Spectroscopy (EELS) are strong candidate techniques for characterizing steel surfaces and substrate-coating interfaces when investigating the selective oxidation and reactive wetting of advanced high strength steels (AHSS) during the continuous galvanizing process. However, unambiguous identification of ternary oxides such as Mn2SiO4, MnSiO3, and MnAl2O4 by XPS or EELS, which can play a significant role in substrate reactive wetting, is difficult due to the lack of fully characterized standards in the literature. To resolve this issue, samples of Mn2SiO4, MnSiO3 and MnAl2O4 were synthesized and characterized by XPS and EELS. The unique features of the XPS and EELS spectra for the Mn2SiO4, MnSiO3 and MnAl2O4 standards were successfully derived, thereby allowing investigators to fully differentiate and identify these oxides at the surface and subsurface of Mn, Si and Al alloyed AHSS using these techniques.

  9. Optical and XPS studies of BCN thin films by co-sputtering of B4C and BN targets

    NASA Astrophysics Data System (ADS)

    Prakash, Adithya; Sundaram, Kalpathy B.

    2017-02-01

    Boron carbon nitride (BCN) thin films are investigated for their optical properties. BCN, is the unanimous choice for inter-dielectric layer (IDL) in very large scale integration (VLSI) because of its low-k dielectric constant. Optical properties can be tailored as a function of elemental composition, which makes BCN a prospective material in UV-filters and mirrors. Films are deposited by reactive co-sputtering of boroncarbide (B4C) and boronnitride (BN) with varying N2/Ar gas flow ratio by DC and RF sputtering respectively. XPS studies are performed to deduce the bonding and chemical properties of the BCN thinfilms. Optical band gap (Eg) studies are performed as a result of varying target powers, gas ratios and deposition temperatures. Eg is found to increase with N2/Ar flow ratios and deposition temperatures. BCN deposited at 20 W DC exhibited higher band gap range and the highest achieved is 3.7 eV at N2/Ar = 0.75. Lowest value achieved is 1.9 eV at N2/Ar = 0.25 for as-deposited films.

  10. Structural environment of uranium (VI) and europium (III) species sorbed onto phosphate surfaces: XPS and optical spectroscopy studies

    SciTech Connect

    Drot, R.; Simoni, E.; Alnot, M.; Ehrhardt, J.J.

    1998-09-15

    In order to characterize the structure of the surface complexes formed by interaction between uranyl and europium (III) ions and the surface of solid matrices, optical and X-ray photoelectron spectroscopies experiments on uranyl/europium loaded phosphate solids have been performed. The use of complimentary spectroscopic techniques allows an identification of the sorption mechanism and a structural characterization of the sorption sites and the sorbed species on phosphate surfaces. The samples were prepared from aqueous uranyl or europium solutions in the pH range from 1.5 to 6.0. The surface coverage was varied from 1 to 40% of a monolayer. The differences between the emission spectra of europium ions either sorbed on the surface of phosphate samples or doped inside the solid unambiguously indicates that these sorbed ions are exclusively located on the surface and that they do not migrate inside the matrix, which shows clearly that surface complexation is involved during the sorption process. The XPS spectrum of uranyl ions sorbed on zirconium diphosphate exhibits only one component, while the spectrum corresponding to uranium on thorium matrix shows two different unresolved peaks attributed to two different chemical environments. These results, corroborated by the uranyl emission spectra and the associated decay times and those obtained by optical spectroscopy of europium sorbed on the same solids, have been interpreted in terms of two sorption sites probably formed by the oxygens of the PO{sub 4} and P{sub 2}O{sub 7} surface groups.

  11. Mutation in the xpsD gene of Xanthomonas axonopodis pv. citri affects cellulose degradation and virulence.

    PubMed

    Baptista, Juliana Cristina; Machado, Marcos Antonio; Homem, Rafael Augusto; Torres, Pablo Sebastián; Vojnov, Adrian Alberto; do Amaral, Alexandre Morais

    2010-01-01

    The Gram-negative bacterium Xanthomonas axonopodis pv. citri, the causal agent of citrus canker, is a major threat to the citrus industry worldwide. Although this is a leaf spot pathogen, it bears genes highly related to degradation of plant cell walls, which are typically found in plant pathogens that cause symptoms of tissue maceration. Little is known on Xac capacity to cause disease and hydrolyze cellulose. We investigated the contribution of various open reading frames on degradation of a cellulose compound by means of a global mutational assay to selectively screen for a defect in carboxymethyl cellulase (CMCase) secretion in X. axonopodis pv. citri. Screening on CMC agar revealed one mutant clone defective in extracellular glycanase activity, out of nearly 3,000 clones. The insertion was located in the xpsD gene, a component of the type II secretion system (T2SS) showing an influence in the ability of Xac to colonize tissues and hydrolyze cellulose. In summary, these data show for the first time, that X. axonopodis pv. citri is capable of hydrolyzing cellulose in a T2SS-dependent process. Furthermore, it was demonstrated that the ability to degrade cellulose contributes to the infection process as a whole.

  12. Single-layer ZnS supported on Au(111): A combined XPS, LEED, STM and DFT study

    NASA Astrophysics Data System (ADS)

    Deng, Xingyi; Sorescu, Dan C.; Lee, Junseok

    2017-04-01

    Single-layer of ZnS, consisting of one atomic layer of ZnS(111) plane, has been grown on Au(111) and characterized using X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). While the LEED measurement indicates a coincidence structure of ZnS-(3×3)/Au(111)-(4×4), high resolution STM images reveal hexagonal unit cells of 6.7×6.7 Å2 and 11.6×11.6 Å2, corresponding to √3 and 3 times the unit cell of the ideal zincblende ZnS-(1×1), respectively, depending on the tunneling conditions. Calculations based on density functional theory (DFT) indicate a significantly reconstructed non-planar structure of ZnS single-layer on Au(111) with 2/3 of the S anions being located nearly in the plane of the Zn cations and the rest 1/3 of the S anions protruding above the Zn plane. The calculated STM image shows similar characteristics to those of the experimental STM image. Additionally, the DFT calculations reveal the different bonding nature of the S anions in ZnS single-layer supported on Au(111).

  13. Eu(III) sorption to TiO2 (anatase and rutile): batch, XPS, and EXAFS studies.

    PubMed

    Tan, Xiaoli; Fan, Qiaohui; Wang, Xiangke; Grambow, Bernd

    2009-05-01

    The sorption of Eu(III) on anatase and rutile was studied as a function of ionic strength, humic acid (HA, 7.5 mg/L), and electrolyte anions over a large range of pH (2-12). The presence of HA significantly affected Eu(III) sorption to anatase and rutile. The sorption of Eu(III) on anatase and rutile was independent of ionic strength. Results of an X-ray photoelectron spectroscopy (XPS) analysis showed that Eu(III) was chemically present within the near-surface of TiO2 due to the formation of triple bond SOEu and triple bond SOHAEu complexes. An extended X-ray absorption fine structure (EXAFS) technique was applied to characterize the local structural environment of the adsorbed Eu(III), and the results indicated that Eu(III) was bound to about seven or eight O atoms at a distance of about 2.40 A. The functional groups of surface-bound HA were expected to be involved in the sorption process. The measured Eu-Ti distance confirmed the formation of inner-sphere sorption complexes on a TiO2 surface.

  14. A study of the initial film growth of PEG-like plasma polymer films via XPS and NEXAFS

    NASA Astrophysics Data System (ADS)

    Li, Yali; Muir, Benjamin W.; Easton, Christopher D.; Thomsen, Lars; Nisbet, David R.; Forsythe, John S.

    2014-01-01

    The chemistry of substrate-film interface (underside) of di(ethylene glycol) dimethyl ether plasma polymer (DGpp) films has been studied directly and compared to the top layer of the film (topside). By depositing the plasma polymer films onto indium tin oxide (ITO) glass, the films were easily delaminated from the substrate. The top- and underside of the films were examined by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It was found that a rapid increase in pressure during plasma polymerization results in steep chemical gradients in the films, while small pressure changes do not lead to chemical gradient formation. These observations validate the findings of previous neutron reflectometry modeling studies of this class of plasma polymer thin film. In addition, subtle variations in plasma polymer film chemistry were observed between different substrates they were deposited onto. This approach will allow additional studies on the mechanisms of early plasma polymer thin film formation with various monomers.

  15. An XPS study of the stability of Fomblin Z25 on the native oxide of aluminum. [x ray photoelectron spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    Thin films of Fomblin Z25, a perfluoropolyalkylether lubricant, were vapor deposited onto clean, oxidized aluminum and sapphire surfaces, and their behavior at different temperatures was studied using x ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). It was found that the interfacial fluid molecules decompose on the native oxide at room temperature, and continue to decompose at elevated temperatures, as previous studies had shown to occur on clean metal. TDS indicated that different degradation mechanisms were operative for clean and oxidized aluminum. On sapphire substrates, no reaction was observed at room temperature. Our conclusion is that the native oxide of aluminum is neither passive nor protective towards Fomblin Z25. At high temperatures (150 C) degradation of the polymer on sapphire produced a debris layer at the interface with a chemical composition similar to the one formed on aluminum oxide. Rubbing a Fomblin film on a single crystal sapphire also induced the decomposition of the lubricant in contact with the interface and the formulation of a debris layer.

  16. The in situ characterization and structuring of electrografted polyphenylene films on silicon surfaces. An AFM and XPS study.

    PubMed

    Ghorbal, Achraf; Grisotto, Federico; Laudé, Marion; Charlier, Julienne; Palacin, Serge

    2008-12-15

    An atomic force microscope was used so as to structure by nanofriction films of polynitrophenylene electrografted on substrates of n-type silicon (100) with the native oxide on the top of the surface. AFM measurements of thin films thickness have been carried out in the electrolytic solution for different applied potentials during the electrografting. This investigation allows (i) to determine the relationship between the applied potential and the final thickness of electrografted polyphenylene films and (ii) to specify how the thin layers grow. XPS analysis confirmed the AFM observations on (i) the effective shaving of the grafted polymer chains under mechanical stress and (ii) the existence of a potential threshold for electrografting a polyphenylene film on silicon oxide surfaces. The presence of a residual film in the rubbed zone was attributed to stronger interactions between the first electrografted layer and the native oxide of silicon (through Si-C or/and Si-O-C bonds) than those insuring the cohesion of the multilayer (C-C and C-N bonds).

  17. A SIMS (secondary ion mass spectrometry) and XPS (X-ray photoelectron spectroscopy) study of dissolving plagioclase

    SciTech Connect

    Muir, I.J. ); Bancroft, G.M.; Nesbitt, H.W. ); Shotyk, W. )

    1990-08-01

    In an earlier report, the authors showed that altered layers formed on the surface of dissolving labradorite feldspar grains, and that the thickness of these layers (up to hundreds of angstroms) is strongly dependent on the pH of the reactant solution. In this paper, they show that the thickness of these altered layers also depends strongly on the composition of the plagioclase feldspar. Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) have been used to characterize these altered layers. During dissolution, Ca and Al are removed from the solid material to form an altered layer residually enriched in Si with very similar profiles for Ca and Al. In acidic solutions (pH 3.5) for 90 days, the altered layers increase in thickness from a few hundred angstroms to many hundred angstroms in the order: albite < oligoclase < labradorite < bytownite. These results emphasize the central role of hydrolysis of the bridging Si-O-Al bonds in the initial weathering process. Analysis by scanning electron microscopy (SEM) does not provide any evidence for the growth of secondary phases. Extensive dissolution features (etch pits) were observed on many of the reacted surfaces.

  18. Near-ambient pressure XPS of high-temperature surface chemistry in Sr2Co2O5 thin films

    DOE PAGES

    Hong, Wesley T.; Stoerzinger, Kelsey; Crumlin, Ethan J.; ...

    2016-02-11

    Transition metal perovskite oxides are promising electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells, but a lack of fundamental understanding of oxide surfaces impedes the rational design of novel catalysts with improved device efficiencies. In particular, understanding the surface chemistry of oxides is essential for controlling both catalytic activity and long-term stability. Thus, elucidating the physical nature of species on perovskite surfaces and their catalytic enhancement would generate new insights in developing oxide electrocatalysts. In this article, we perform near-ambient pressure XPS of model brownmillerite Sr2Co2O5 (SCO) epitaxial thin films with different crystallographic orientations. Detailed analysis of themore » Co 2p spectra suggests that the films lose oxygen as a function of temperature. Moreover, deconvolution of the O 1s spectra shows distinct behavior for (114)-oriented SCO films compared to (001)-oriented SCO films, where an additional bulk oxygen species is observed. These findings indicate a change to a perovskite-like oxygen chemistry that occurs more easily in (114) SCO than (001) SCO, likely due to the orientation of oxygen vacancy channels out-of-plane with respect to the film surface. This difference in surface chemistry is responsible for the anisotropy of the oxygen surface exchange coefficient of SCO and may contribute to the enhanced ORR kinetics of La0.8Sr0.2CoO3-δ thin films by SCO surface particles observed previously.« less

  19. Conservation of artists' acrylic emulsion paints: XPS, NEXAFS and ATR-FTIR studies of wet cleaning methods

    DOE PAGES

    Willneff, E. A.; Ormsby, B. A.; Stevens, J. S.; ...

    2014-02-17

    Works of art prepared with acrylic emulsion paints became commercially available in the 1960s. It is increasingly necessary to undertake and optimise cleaning and preventative conservation treatments to ensure their longevity. Model artists' acrylic paint films covered with artificial soiling were thus prepared on a canvas support and exposed to a variety of wet cleaning treatments based on aqueous or hydrocarbon solvent systems. This included some with additives such as chelating agents and/or surfactants, and microemulsion systems made specifically for conservation practice. The impact of cleaning (soiling removal) on the paint film surface was examined visually and correlated with resultsmore » of attenuated total reflection Fourier transform infrared, XPS and near-edge X-ray absorption fine structure analyses – three spectroscopic techniques with increasing surface sensitivity ranging from approximately $-$ 1000, 10 and 5 nm, respectively. Visual analysis established the relative cleaning efficacy of the wet cleaning treatments in line with previous results. X-ray spectroscopy analysis provided significant additional findings, including evidence for (i) surfactant extraction following aqueous swabbing, (ii) modifications to pigment following cleaning and (iii) cleaning system residues.« less

  20. Conservation of artists' acrylic emulsion paints: XPS, NEXAFS and ATR-FTIR studies of wet cleaning methods

    SciTech Connect

    Willneff, E. A.; Ormsby, B. A.; Stevens, J. S.; Jaye, C.; Fischer, D. A.; Schroeder, S. L. M.

    2014-02-17

    Works of art prepared with acrylic emulsion paints became commercially available in the 1960s. It is increasingly necessary to undertake and optimise cleaning and preventative conservation treatments to ensure their longevity. Model artists' acrylic paint films covered with artificial soiling were thus prepared on a canvas support and exposed to a variety of wet cleaning treatments based on aqueous or hydrocarbon solvent systems. This included some with additives such as chelating agents and/or surfactants, and microemulsion systems made specifically for conservation practice. The impact of cleaning (soiling removal) on the paint film surface was examined visually and correlated with results of attenuated total reflection Fourier transform infrared, XPS and near-edge X-ray absorption fine structure analyses – three spectroscopic techniques with increasing surface sensitivity ranging from approximately $-$ 1000, 10 and 5 nm, respectively. Visual analysis established the relative cleaning efficacy of the wet cleaning treatments in line with previous results. X-ray spectroscopy analysis provided significant additional findings, including evidence for (i) surfactant extraction following aqueous swabbing, (ii) modifications to pigment following cleaning and (iii) cleaning system residues.